Field of the Invention

The present invention relates to the transport of particulate material, such as to apparatus for transporting particulate material and to methods fortransporting particulate material. The invention has particular, although not necessarily exclusive, application to the transport of granular material.

Granular materials include widely traded commodities encompassing fuels, foods, and industrial feedstocks. They are also frequently encountered in drilling, exploration, and comminution. However, they are difficult to transport against gravity. Augers and screw conveyors can be used, as can bailing, gas-blowing, and vibro-conveyors, but all have issues related to various combinations of choking, friction, erosion, complexity, filtration, and inclination angle.

Augering is ubiquitous in drilling applications. However, it requires a certain minimum speed, particularly in smaller diameter holes [1], At depth, the power required to rotate an auger-drill may well exceed the power expended on the drilling process itself, and a great deal of torque must be reacted.

Screw conveyors, first reported by Archimedes in 234 BC, have some more flexibility because they may use centreless or flexible augers [2], Although their throughput also declines with angle, and they often require a starting torque far in excess of steady-state [3], they can give consistent results in transport applications [4],

Gas-blowing requires a fluid and filtration system, and bailing is a mechanically-complex process. The leading competitor to the auger in many applications is therefore the vibro-conveyor, which uses a complex vibrational pattern to cause a particle to break contact with an inclined plane, fly a short trajectory, and touchdown further up the same inclined plane [5], Although the need for relative movement of the parts of the system is eliminated, which can help to prevent jamming, friction remains a crucial parameter and hence there is some sensitivity to the target material. Inclined planes can be wound into a spiral conveyor to approximate vertical transport, but the spiral radius and vulnerability to shock prevents widespread downhole applications.

Downhole work at small diameters, and without rotation, is therefore one of the most challenging contexts for the transport of granular materials. The relative motion of bristled surfaces is one option [6], but uplift under such circumstances remains a limiting factor in the design of many exploration systems.

The present invention has been devised in light of the above considerations.

Summary of the Invention

The present inventors have realised that it would be advantageous to consider a particulate transportation mechanism that permits vertical transport of particulates without the need for rotation required by an auger. The inventors have devised an approach in which a reciprocation motion is harnessed in order to cause particles to be thrown from one pocket to the next in an overall upright direction within a reciprocation mechanism.

Accordingly, in a first aspect, the present invention provides a particulate transport apparatus comprising a reciprocation mechanism having a lower end and an upper end, the reciprocation mechanism comprising a sequence of pockets arranged along a particulate transport path of the reciprocation mechanism, each pocket being arranged so that, when the reciprocation mechanism is arranged in an upright orientation and caused to reciprocate with a source of particulate at the lower end of the reciprocation mechanism, particulate is thrown from each pocket in the sequence to a respective next pocket in the sequence to effect an overall upright particulate transport path towards the upper end of the reciprocation mechanism.

In a second aspect, the present invention provides a method of operating a particulate transport apparatus to transport particulate, the particulate transport apparatus comprising a reciprocation mechanism having a lower end and an upper end, the reciprocation mechanism comprising a sequence of pockets arranged along a particulate transport path of the reciprocation mechanism, wherein the method includes arranging the reciprocation mechanism in a substantially upright orientation and causing the reciprocation mechanism to reciprocate with a source of particulate at the lower end of the reciprocation mechanism, so that particulate is thrown from each pocket in the sequence to a respective next pocket in the sequence to effect an overall substantially upright particulate transport path towards the upper end of the reciprocation mechanism.

Optional features of the invention are now set out. These may be combined singly or in any combination with any aspect of the invention.

The term “reciprocation” is used herein. In some embodiments, the motion of the reciprocation mechanism is substantially one dimensional, that is substantially only along one direction. That one direction may for example be aligned with the overall particulate transport path through the reciprocation mechanism. A suitable reciprocation may for example be sinusoidal. This is analytically easy to model. However, the present invention is not necessarily limited to such reciprocation. More complex reciprocation patterns are possible, whether in one dimension or more than one dimension. Furthermore, the present invention is not necessarily limited to a cyclically perfectly repeating reciprocation motion. More noisy and/or random reciprocation motion can provide acceptable results. In some circumstances, the reciprocation motion can be considered to be vibration, particularly when the reciprocation motion is continuous or quasi-continuous. In other circumstances, the reciprocation motion can be considered to be pulsed, particularly when the reciprocation motion is applied in individual impulses or in short bursts of cycles.

There may be provided a reciprocation actuator. The reciprocation actuator may be configured to cause reciprocation of the reciprocation mechanism. The reciprocation actuator may form part of the apparatus. However, this is not necessarily essential, particularly in the case where the particulate transport apparatus is coupled to a system which provides suitable actuation. For example, in the case of a drilling system, the drilling system itself may be powered to rotate and/or reciprocate and this may provide suitable actuation, via a suitable coupling arrangement, for reciprocating the reciprocation mechanism of the particulate transport apparatus.

The frequency of reciprocation of the reciprocation mechanism is not particularly limited, for the reasons explained in more detail later. However, typically, the frequency of reciprocation is at least 5 Hz, more preferably at least 10 Hz, and may be at least 20 Hz, at least 30 Hz, at least 40 Hz or at least 50 Hz, for example, depending on the circumstances. Typically, the frequency of reciprocation is not more than 200 Hz, more preferably not more than 150 Hz.

The amplitude of reciprocation of the reciprocation mechanism is similarly not particularly limited, as will also be explained.

Of greater relevance is considered to be the intensity of reciprocation (or vibration). This can be described in terms of acceleration experienced by a pocket of the reciprocation mechanism. In some embodiments, the reciprocation mechanism is reciprocated with an intensity defined by the acceleration F g greater than 1 g, where F g = Aw ² , in which:

A is the amplitude of reciprocation w is 2nf and f is the frequency of reciprocation g is the acceleration due to gravity

F is the relative acceleration, a dimensionless number.

The inventors here introduce the concepts of “activation acceleration” and “saturation acceleration” based on their analytical and empirical work.

For a population of particles in the apparatus, the activation acceleration is considered to correspond to the lowest intensity of operation of the reciprocation mechanism at which the particles are able to “climb” through the reciprocation mechanism. This therefore corresponds to the acceleration needed for the particles to be thrown from one pocket to the next in the sequence of pockets.

For the population of particles in the apparatus, the saturation acceleration is considered to correspond to the lowest intensity of operation of the reciprocation mechanism at which each pocket in the apparatus can be fully emptied by the particles climbing all the way through the reciprocation mechanism. This corresponds to an acceleration greater than the activation acceleration, for the same frequency of operation.

Considering a simple sinusoidal vibration of the reciprocation mechanism with the reciprocation mechanism oriented upright and with the vibration applied in the upright direction, the frequency of the vibration can be determined. For a particular frequency of vibration, the intensity of operation of the reciprocation mechanism can be increased by increasing the amplitude of the vibration. Similarly, considering the same simple sinusoidal vibration of the reciprocation mechanism with the reciprocation mechanism oriented upright and with the vibration applied in the upright direction, the amplitude of the vibration can be determined. For a particular amplitude of vibration, the intensity of operation of the reciprocation mechanism can be increased by increasing the frequency of the vibration.

In view of the relation F g = Aw ² , it is considered that for a particular reciprocation mechanism, the activation acceleration required by that reciprocation mechanism increases with frequency. Similarly, the saturation acceleration required by that reciprocation mechanism increases with frequency.

In some embodiments, the activation acceleration is at least 1.1 g, at least 1 .2 g, at least 1 .3 g, at least 1 .4 g, at least 1 .5 g, at least 1 .6 g, at least 1 .8 g, at least 2 g, at least 2.5 g, at least 3 g, at least 4 g, at least 5 g, at least 6 g, at least 7 g, at least 8 g, at least 9 g, or at least 10 g.

In some embodiments, the saturation acceleration is at least 2 g, at least 2.1 g, at least 2.2 g, at least 2.3 g, at least 2.4 g, at least 2.5 g, at least 2.6 g, at least 2.8 g, at least 3 g, at least at least 4 g, at least 5 g, at least 6 g, at least 7 g, at least 8 g, at least 9 g, at least 10 g, at least 11 g, at least 12 g, at least 13 g, at least 14 g, at least 15 g, at least 16 g, at least 17 g, or at least 18 g.

In some embodiments, the reciprocation mechanism has a principal axis. The principal axis may correspond to the overall particulate transport path through the reciprocation mechanism. The pockets may be arranged on opposing sides of the principal axis. There may be an array of pockets at one side of the principal axis, designated as side A, and an array of pockets at the other side of the principal axis, designated as side B. In this way, there can be designated pockets A and pockets B. Pockets A may be arranged so that, when the reciprocation mechanism is oriented upright, pockets A are aligned along axis A which is substantially parallel to the principal axis. Pockets B may be arranged so that, when the reciprocation mechanism is oriented upright, pockets B are aligned along axis B which is substantially parallel to the principal axis. As will be understood, axis A and axis B are offset from each other.

Pockets A may have a uniform pitch along axis A. Pockets B may have the same uniform pitch along axis B. Typically, the position of pockets A along axis A relative to the position of pockets B along axis B is staggered. Accordingly, in some embodiments when the reciprocation mechanism is oriented upright, the vertical position of a pocket B is mid-way between the vertical position of two vertically adjacent pockets A. Thus, the vertical position of pockets B is typically vertically staggered from the vertical position of pockets A by a vertical distance of about one half of the pitch between pockets A.

Each pocket may have a base and a back wall. The base and/or the back wall may have a scoop or scallop shape. The back wall may be closed. In this way, there may be defined in the pocket a line or point of lowest position in the pocket. The intention here is that, assuming negligible friction, this is the position at which a single particle would rest in the pocket when the apparatus is at rest but held in an upright orientation. When considering the “position” and “pitch” of the pockets, it is possible to use the lowest position in each pocket as a reference.

Each pocket may have an opening. The opening may face towards the principal axis. Accordingly, pockets A and pockets B may open towards each other.

Each pocket may have a lip which forms part of the base surface of the pocket. When the reciprocation mechanism is oriented upright, the lip may slant upwardly with respect to the lowest position in the pocket. The opening of the pocket is defined above the lip of the pocket.

Above each pocket may be an associated deflector. The deflector extends from the back wall of the pocket towards, and in some cases past, the principal axis. In some embodiments, the deflector reaches but does not extend past the principal axis. When the reciprocation mechanism is oriented upright, the deflector may slant upwardly.

Conveniently, each deflector may be provided by the lower surface of the lip of the pocket above.

The scoop shape of the base may provide the lowest position in each pocket. For pockets A, for example, axis A may pass through these lowest positions in each pocket A. For pockets B, axis B may pass through these lowest positions in each pocket B.

In view of the scoop shape of the base (also referred to herein as a scallop shape, referencing the overall internal cross sectional scoop shape of one half of a scallop shell), the lowest position in the base of a particular pocket may therefore set away from the back wall of the pocket. Accordingly, axis A and axis B may be set away from the back walls of their respective pockets. Axis A and axis B may thereby be positioned intermediate principal axis X and the back walls.

In some embodiments, shape of the pockets is a curved shape. Accordingly, both the base of the pocket and the back wall may be curved.

We now consider the shape of the lip and the shape of the pocket and deflector associated with the lip. The lip has an upper surface (which may extend into the base of a pocket) and a lower surface (which may extend to form the deflector and the back wall of the pocket below). The vertical distance between the upper and lower surfaces of the lip may increase with position away from the principal axis X. In other words, the lip may have a tapered shape with thickness increasing in the direction away from the principal axis X.

In operation, particles may be held at the base of each pocket. As the reciprocation mechanism reciprocates, particles are thrown upwardly and may impact with a deflector, deflecting the particles into the next pocket in the sequence. In the illustration provided above, this means that particles travel from one pocket A to the next pocket B and then to the next pocket A and then to the next pocket B, and so on. The pocket lips and the deflectors may be oriented so that, during this operation, it is more likely than not that each particle will travel upwardly through the sequence of pockets rather than downwardly.

In some embodiments, the lips and the deflectors are shaped and oriented so that there is no straight line path through the reciprocation mechanism which avoids intercepting the lips and/or deflectors. In this way, it becomes less likely that particles will full downwardly through the reciprocation mechanism when the reciprocation mechanism is oriented upright and operated.

When the reciprocation mechanism is oriented upright, for a particular pocket, the end of the lip of the pocket may be at a vertical height above the lowest position in the pocket corresponding to at least 10% of the pitch between adjacent pockets on one side of the principal axis. That is, taking pockets A for example, the end of the lip of one pocket A may be at a vertical height above the lowest position in the pocket corresponding to at least 10% of the pitch between adjacent pockets A. This vertical height may be, for example, at most 40% of the pitch.

In operation, the amplitude of reciprocation of the reciprocation mechanism may be at least sufficient to cause ballistic flight of particles in one pocket into the next pocket in the sequence at a higher elevation. In some embodiments, the ballistic flight may be assisted or impeded by the passage of gas through the reciprocation mechanism. The flow of gas may be in any suitable direction, for example aligned with or aligned against the overall particulate transport path. A suitable amplitude of reciprocation is dependent, at least in part, on the frequency of reciprocation. However, for example, the amplitude of reciprocation may be on the order of the pitch between adjacent pockets. In some embodiments, the amplitude of reciprocation may be in the range of 0.5 to 1 .5 times the pitch between adjacent pockets.

In some embodiments, pockets A and B reciprocate in phase. In this case, pockets A and B may be constructed so as to be movable in a fixed relationship to each other.

Embodiments of the invention are considered to have particular utility in particulate transport where space is limited. For example, the particulate transport apparatus may be provided as part of a drilling system arranged to drill in a downhole. The drilling system may include a drill bit with a particulate transport apparatus formed inside the drill bit, so that vibration of the drill bit with respect to the downhole produces particulate spoil and the particulate spoil is conducted to an inlet of the particulate transport apparatus and upwardly internally of the drill bit to reach an outlet of the particulate transport apparatus.

For the avoidance of doubt, it is noted here that the discussion of operation of the apparatus related to the reciprocation mechanism being arranged in an upright orientation does not necessarily mean that the apparatus must only be operated in such an orientation. Suitable operation may also be achieved when the reciprocation mechanism is arranged obliquely to an upright orientation, as may be required in various practical circumstances. It is intended, however, that the apparatus is capable of operating suitably when the reciprocation mechanism is arranged in an upright orientation. The inventors have made further investigations of the principles underlying the present invention and have realised that further embodiments are possible which provide still further flexibility in the implementation of the invention and the direction of particulate transport.

Accordingly, in a third aspect, the present invention provides a particulate transport apparatus comprising a reciprocation mechanism having a first end and a second end, the reciprocation mechanism comprising a sequence of pockets arranged along a particulate transport path of the reciprocation mechanism, each pocket being arranged so that, when the reciprocation mechanism is arranged in a substantially horizontal orientation and caused to reciprocate in a substantially vertical direction with a source of particulate at the first end of the reciprocation mechanism, particulate is thrown from each pocket in the sequence to a respective next pocket in the sequence to effect an overall substantially horizontal particulate transport path towards the second end of the reciprocation mechanism, the reciprocation mechanism having a principal axis corresponding to the overall particulate transport path, wherein there is an array of pockets at one side of the principal axis, designated as side A, and an array of pockets at the other side of the principal axis, designated as side B, thereby providing designated pockets A and pockets B, and wherein pockets A are arranged so that, when the reciprocation mechanism is oriented horizontally, pockets A are aligned along axis A which is substantially parallel to the principal axis and pockets B are arranged so that, when the reciprocation mechanism is oriented horizontally, pockets B are aligned along axis B which is substantially parallel to the principal axis, wherein axis A and axis B are offset from each other, and wherein pockets A have a uniform pitch along axis A and pockets B have the same uniform pitch along axis B, and the position of pockets A along axis A relative to the position of pockets B along axis B is staggered and wherein pockets A and pockets B open towards each other.

In a fourth aspect, the present invention provides a method of operating a particulate transport apparatus to transport particulate, the particulate transport apparatus comprising a reciprocation mechanism having a first end and a second end, the reciprocation mechanism comprising a sequence of pockets arranged along a particulate transport path of the reciprocation mechanism, the method including arranging the reciprocation mechanism in a substantially horizontal orientation and causing the reciprocation mechanism to reciprocate in a substantially vertical direction with a source of particulate at the first end of the reciprocation mechanism, each pocket being arranged so that particulate is thrown from each pocket in the sequence to a respective next pocket in the sequence to effect an overall substantially horizontal particulate transport path towards the second end of the reciprocation mechanism, the reciprocation mechanism having a principal axis corresponding to the overall particulate transport path, wherein there is an array of pockets at one side of the principal axis, designated as side A, and an array of pockets at the other side of the principal axis, designated as side B, thereby providing designated pockets A and pockets B, and wherein pockets A are arranged so that pockets A are aligned along axis A which is substantially parallel to the principal axis and pockets B are arranged so that pockets B are aligned along axis B which is substantially parallel to the principal axis, wherein axis A and axis B are offset from each other, and wherein pockets A have a uniform pitch along axis A and pockets B have the same uniform pitch along axis B, and the position of pockets A along axis A relative to the position of pockets B along axis B is staggered and wherein pockets A and pockets B open towards each other.

It is considered that the significance of the third and fourth aspects is that it is possible to effect substantially horizontal particulate transport even with substantially vertical reciprocation.

Various features disclosed with respect to the first and second aspects of the invention can be seen to apply also to the third and/or fourth aspects, unless the context demands otherwise.

Further optional features are now set out.

In the reciprocation mechanism to be discussed, when arranged substantially horizontally, pockets A may be arranged below the principal axis and pockets B may be arranged above the principal axis.

Considering for example each pocket A, each such pocket may have a rear wall that is downwardly sloping with respect to the overall particulate transport path and a front wall that is upwardly sloping with respect to the overall particulate transport path. The rear wall may be closer to the first end compared with the front wall. Similarly, the front wall may be closer to the second end compared with the rear wall.

Between the rear wall and front wall there may be a base region. The base region may have a scoop shape. The rear wall, base region and front wall may together have an overall curved shape.

Considering next each pocket B, each such pocket may have a rear wall that is upwardly sloping with respect to the overall particulate transport path and a front wall that is downwardly sloping with respect to the overall particulate transport path. The rear wall may be closer to the first end compared with the front wall. Similarly, the front wall may be closer to the second end compared with the rear wall.

Between the rear wall and front wall there may be a base region. The base region may have a scoop shape. The rear wall, base region and front wall may together have an overall curved shape.

Considering the lowest position in the base region of pockets A and the highest position in the base region of pockets B, the staggered arrangement of pockets A and B may be such that the highest position in the base region of one pocket B is arranged at a position that is half way or about half way between the lowest positions in the base regions of two adjacent pockets A.

In some embodiments, the base region of each pocket A is formed in register with the rear wall of a respective pocket B. Considering the principal axis, it is possible to consider the slope or average slope of the front and rear walls with respect to the principal axis. In some embodiments, the slope (or average slope) of the front wall is steeper than that of the rear wall.

For ease of reference, it is possible to consider the depth of each pocket A as the distance (vertical distance, when the reciprocation mechanism is arranged horizontally) from the lowest point or line of the base region to the highest point or line of the highest of the rear wall and front wall. In some embodiments, the rear wall and the front wall have the same height. It is then possible to consider the base region of the pocket as that part of the pocket extending to a height of one half of the depth ofthe pocket.

In operation of the particulate transport apparatus, particulate may be thrown from a pocket A to hit the rear wall of a corresponding pocket B to be deflected towards the second end and to be caught in a subsequent pocket A in the sequence of pockets.

The inventors have realised that still further embodiments are possible which provide still further flexibility in the implementation of the invention and the direction of particulate transport. Of particular interest is an approach in which the operational principles of some of the preceding aspects are combined so as to provide a combination of particulate transport directions through the apparatus.

Accordingly, in a fifth aspect, the present invention provides a particulate transport apparatus comprising a reciprocation mechanism, the reciprocation mechanism comprising an upright sequence of pockets arranged along an upright particulate transport path of the reciprocation mechanism, each pocket being arranged so that, when the upright sequence of pockets is arranged in an upright orientation and caused to reciprocate in a substantially vertical direction with a source of particulate at a lower end of the upright sequence of pockets, particulate is thrown from each pocket in the upright sequence to a respective next pocket in the upright sequence to effect an overall upright particulate transport path towards an upper end of the upright sequence of pockets, the reciprocation mechanism further comprising a substantially horizontal sequence of pockets, disposed in series with the upright sequence of pockets, the substantially horizontal sequence of pockets being arranged along a substantially horizontal particulate transport path of the reciprocation mechanism, each pocket being arranged so that, when the substantially horizontal sequence of pockets is arranged in a substantially horizontal orientation and caused to reciprocate in a substantially vertical direction with a source of particulate at a first end of the substantially horizontal sequence of pockets, particulate is thrown from each pocket in the sequence to a respective next pocket in the sequence to effect an overall substantially horizontal particulate transport path towards a second end of the substantially horizontal sequence of pockets, wherein, in use, particulate is transported from the upright sequence of pockets to the substantially horizontal sequence of pockets by said reciprocation or particulate is transported from the substantially horizontal sequence of pockets to the upright sequence of pockets by said reciprocation.

In a sixth aspect, the present invention provides a method of operating a particulate transport apparatus, the particulate transport apparatus comprising a reciprocation mechanism, the reciprocation mechanism comprising an upright sequence of pockets arranged along an upright particulate transport path of the reciprocation mechanism, the method including causing the reciprocation mechanism to reciprocate in a substantially vertical direction with a source of particulate at a lower end of the upright sequence of pockets with the reciprocation mechanism arranged in an upright orientation, each pocket being arranged so that particulate is thrown from each pocket in the upright sequence to a respective next pocket in the upright sequence to effect an overall upright particulate transport path towards the upper end of the upright sequence of pockets, the reciprocation mechanism further comprising a substantially horizontal sequence of pockets, disposed in series with the upright sequence of pockets, the substantially horizontal sequence of pockets being arranged along a substantially horizontal particulate transport path of the reciprocation mechanism, each pocket being arranged so that, due to the reciprocation in the substantially vertical direction and with a source of particulate at a first end of the substantially horizontal sequence of pockets, particulate is thrown from each pocket in the sequence to a respective next pocket in the sequence to effect an overall substantially horizontal particulate transport path towards a second end of the substantially horizontal sequence of pockets, wherein, in use, particulate is transported from the upright sequence of pockets to the substantially horizontal sequence of pockets by said reciprocation or particulate is transported from the substantially horizontal sequence of pockets to the upright sequence of pockets by said reciprocation.

Features of the first and second aspects of the invention may be applied in any combination to the fifth or sixth aspects and in particular with respect to the upright sequence of pockets.

Features of the third and fourth aspects of the invention may be applied in any combination to the fifth or sixth aspects and in particular with respect to the substantially horizontal sequence of pockets.

The invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided.

Summary of the Fiqures

Embodiments and experiments illustrating the principles of the invention will now be discussed with reference to the accompanying figures in which:

Fig. 1 shows a schematic apparatus intended to illustrate the operation of an embodiment of the invention. Fig. 2 shows an analysis of the trajectory of a single particle (red in the original) attempting to reach the position of the scoop above (blue in the original) from the scoop below (green in the original). Frequency of reciprocation is 10Hz and acceleration is 2.4g. The hop is only just successful, so this is considered to be the limiting ‘saturation’ state.

Fig. 3 shows a view of an arrangement used to carry out a single-particle 2-D finite element model to analyse the operation of an apparatus according to an embodiment of the invention. The left hand side shows the reciprocation mechanism as a whole and the right hand side shows an enlarged view of the bottom pocket.

Fig. 4 shows a view of an arrangement used to carry out a multi-particle 2-D finite element model to analyse the operation of an apparatus according to an embodiment of the invention. The left hand side shows the reciprocation mechanism as a whole and the right hand side shows an enlarged view of the bottom pocket.

Fig. 5 shows the local trajectory of a single particle during 1 second of excitation, at 2 g, modelled using the arrangement illustrated in Fig. 3. (The 1 g case is not shown, because in that case the particle simply remained within the lowest scoop in this model.)

Fig. 6 shows the local trajectory of a single particle during 1 second of excitation, at 3 g, modelled using the arrangement illustrated in Fig. 3.

Fig. 7 shows the local trajectory of a single particle during 1 second of excitation, at 4 g, modelled using the arrangement illustrated in Fig. 3.

Fig. 8 shows the local trajectory of a single particle during 1 second of excitation, at 5 g, modelled using the arrangement illustrated in Fig. 3.

Fig. 9 shows the particle distribution after different times (0 s (red in the original), 0.3 s (orange in the original), 0.6 s (green in the original), and 0.9 s (blue in the original)) at 10 Hz and at 1g, in an apparatus modelled using the arrangement illustrated in Fig. 4.

Fig. 10 shows the particle distribution after different times (0 s (red in the original), 0.3 s (orange in the original), 0.6 s (green in the original), and 0.9 s (blue in the original)) at 10 Hz and at 2g, in an apparatus modelled using the arrangement illustrated in Fig. 4.

Fig. 11 shows the particle distribution after different times (0 s (red in the original), 0.3 s (orange in the original), 0.6 s (green in the original), and 0.9 s (blue in the original)) at 10 Hz and at 3g, in an apparatus modelled using the arrangement illustrated in Fig. 4. Fig. 12 shows the particle distribution after different times (0 s (red in the original), 0.3 s (orange in the original), 0.6 s (green in the original), and 0.9 s (blue in the original)) at 10 Hz and at 4g, in an apparatus modelled using the arrangement illustrated in Fig. 4.

Fig. 13 shows the particle distribution after different times (0 s (red in the original), 0.3 s (orange in the original), 0.6 s (green in the original), and 0.9 s (blue in the original)) at 10 Hz and at 5g, in an apparatus modelled using the arrangement illustrated in Fig. 4.

Fig. 14 shows the particle distribution in the apparatus at Os, which will subsequently be subjected to initialisation at 5g.

Fig. 15 shows the particle distribution in the apparatus at 0.3s, during initialisation at 5g.

Fig. 16 shows the particle distribution in the apparatus at 0.6s, during initialisation at 5g.

Fig. 17 shows the particle distribution in the apparatus at 0.9s, during initialisation at 5g.

Fig. 18 shows a schematic view of an apparatus according to an embodiment of the invention used for experimental tests. Vibration is indicated by the arrows, granular material by the dots.

Fig. 19 shows a graph of the mass of granular material conveyed to the mass balance against time of operation of the apparatus of Fig. 18 when vibrated at 10Hz at the acceleration values indicated.

Fig. 20 shows a graph of the mass of granular material conveyed to the mass balance against time of operation of the apparatus of Fig. 18 when vibrated at 20Hz at the acceleration values indicated.

Fig. 21 shows a graph of the mass of granular material conveyed to the mass balance against time of operation of the apparatus of Fig. 18 when vibrated at 30Hz at the acceleration values indicated.

Fig. 22 shows a graph of the mass of granular material conveyed to the mass balance against time of operation of the apparatus of Fig. 18 when vibrated at 40Hz at the acceleration values indicated.

Fig. 23 shows a graph of the mass of granular material conveyed to the mass balance against time of operation of the apparatus of Fig. 18 when vibrated at 50Hz at the acceleration values indicated.

Fig. 24 presents mass flow rate against acceleration for different vibrational frequencies, compiled using the data of Figs. 19-23. Each datapoint in this graph represents the gradient of a line in Figs. 19-23.

Fig. 25 shows a schematic cross sectional view of an apparatus according to an embodiment of the invention used for uplifting sand. Fig. 26 shows a schematic perspective cross sectional view of a drill bit embodying the present invention, the drill bit containing a pulse-elevator, allowing uplift of spoil without gross rotation of the drill bit itself.

Fig. 27 shows a schematic perspective illustration of a particulate transport apparatus according to a further embodiment.

Fig. 28 shows a partial enlarged view of part of Fig. 27.

Fig. 29 shows the same illustration as Fig. 27 but marked up to indicate further features of interest of the embodiment.

Detailed Description of the Invention

Aspects and embodiments of the present invention will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference.

The embodiments of the present invention rely on a new approach to transportation of particulate materials such as granular materials. Some embodiments are referred to here as a “pulse-elevator”. The pulse-elevator uses a modified and enhanced version of the micro-throwing technique employed in vibroconveyors. This allows vertical transport to be enabled. The mechanism does not depend on friction and appears to be highly robust against shock. Potential applications include non-augering drills, powder metering, and transport.

As explained in more detail below, the operating principles of the disclosed embodiments are well- understood by the present inventors. Functional tests on real-world granular materials show positive results.

The present inventors propose that reliance on particle friction and relative motion could be eliminated, in this and other applications, by using the pulse-elevator geometry.

Partially inspired by the Tesla valve [7], a pulse-elevator according to an embodiment of the invention consists of a series of opposing pockets or scoops that prevent particles from falling down - even under intense shock - but which present little obstacle to upwards motion. When the device is vibrated at an intensity that significantly exceeds F=1 , where the relative acceleration F = Aw ² 1 g, the contents of each pocket or scoop are projected upwards and are deflected into the opposing pocket or scoop on the other side of the device, where the cycle repeats. Each pocket or scoop ejects its contents into the opposing scoop above, just before it is refilled by the opposing pocket or scoop below. The vibration pattern itself can be simple, in contrast to the vibro-conveyor, because a sinusoidal motion (or indeed, almost any oscillating motion) in one degree of freedom is adequate.

In the expression F = Aw ² / g : w = 2nf g is acceleration due to gravity A is the amplitude of vibration

Accordingly, in an embodiment, a particulate transport apparatus comprises a reciprocation mechanism having a lower end and an upper end, the reciprocation mechanism comprising a sequence of pockets arranged along a particulate transport path of the reciprocation mechanism. Each pocket is arranged so that, when the reciprocation mechanism is arranged in an upright orientation and caused to reciprocate with a source of particulate at the lower end of the reciprocation mechanism, particulate is thrown from each pocket in the sequence to a respective next pocket in the sequence to effect an overall upright particulate transport path towards the upper end of the reciprocation mechanism.

Fig. 1 shows a simple testbed for this device. Note that a cover that would be present over the front of the device is omitted from the view. The apparatus is general is indicated by reference number 10. The reciprocation mechanism in this embodiment can for example be formed by 3D printing or by moulding. Granular material 12 is placed in bottom chamber 14, which feeds downhill via an inlet channel 16 into the pulse-elevator geometry. The pulse-elevator geometry is defined by a sequence of pockets 18, arranged in two groups with respect to a principal axis X. Pockets A are formed on one side of the principal axis X and pockets B are formed on the opposed side of principal axis X. When the apparatus is oriented upright, the principal axis X is also oriented upright. Pockets A have a uniform pitch and pockets B have the same uniform pitch. However, the position of pockets A relative to the position of pockets B is staggered. Accordingly, when the reciprocation mechanism is oriented upright, the vertical position of a pocket B is mid-way between the vertical position of two vertically adjacent pockets A. Thus, the vertical position of each pocket B is vertically staggered from the vertical position of a corresponding pocket A by a vertical distance of about one half of the pitch between pockets A.

Each pocket has a base 20 and a back wall 22. In the embodiments, the pocket has a scoop or scallop shape. The back wall 22 is closed. Each pocket has an opening. The opening faces towards the principal axis X and so as shown, pockets A and pockets B open towards each other.

Each pocket has a lip 24 which forms part of the base surface of the pocket. When the reciprocation mechanism is oriented upright, the lip 24 slants upwardly with respect to the lowest position in the pocket. The opening of the pocket is defined above the lip of the pocket.

Above each pocket is an associated deflector 26 which is provided by the lower surface of the lip 24 of the pocket above. The deflector 26 extends from the back wall 22 of the pocket towards and past the principal axis X. When the reciprocation mechanism is oriented upright, the deflector 26 slants upwardly.

The scoop shape of the base 20 provides the lowest position in each pocket. For pockets A, for example, axis A passes through these lowest positions in each pocket A. For pockets B, axis B passes through these lowest positions in each pocket B. In view of the scoop shape of the base (also referred to herein as a scallop shape, referencing the overall internal cross sectional scoop shape of one half of a scallop shell), the lowest position in the base of a particular pocket is therefore set away from the back wall 22 of the pocket. The effect of this is that axis A and axis B are set away from the back walls of their respective pockets, thereby being positioned intermediate principal axis X and the back walls. As can be seen from the drawings, the back walls are curved and therefore each back wall defines a point or line of maximum distance from the principal axis X. Taking pockets A for example, this line of maximum distance for pockets A from principal axis X can be identified as the back wall A line BWA. Taking pockets B, this line of maximum distance for pockets B from principal axis X can be identified as the back wall B line BWB.

As mentioned above, axis A is positioned intermediate BWA and the principal axis X. Considering the distance between BWA and the principal axis X, axis A may be positioned at least 10% of this distance away from both BWA and the principal axis X, or at least 20% of this distance, or at least 30% of this distance.

Similarly, axis B is positioned intermediate BWB and the principal axis X. Considering the distance between BWB and the principal axis X, axis B may be positioned at least 10% of this distance away from both BWB and the principal axis X, or at least 20% of this distance, or at least 30% of this distance.

In the embodiment described, the pocket shape is curved. That is, both the base of the pocket and the back wall are curved. In view of this, it is convenient to consider a delineation of the part of the pocket to be considered the base and the part of the pocket to be considered the back wall. Accordingly, for the purposes of this disclosure, for a particular pocket, the maximum height of the lip 24 with respect to the lower position in the base of the pocket is identified. At the same height at the back of the pocket can be considered to be the junction between the back wall and the base of the pocket. Vertically above this junction can be considered to be the junction between the back wall and the deflector extending above the pocket.

A further point to note about the construction of the pulse-elevator geometry in the embodiment is the shape of the lip 24 and the shape of the pocket 18 and deflector 26 associated with the lip. The lip has an upper surface (extending into the base of a pocket) and a lower surface (extending to form the deflector 26 and the back wall 22 of the pocket below). The vertical distance between the upper and lower surfaces of the lip increases with position away from the principal axis X. In other words, the lip has a tapered shape with thickness increasing in the direction away from the principal axis X.

With each vibration cycle the particles 12 have a good chance of hopping up and over to the next opposing pocket 18, above their starting point, until they reach the top pocket 28 of the apparatus. They will then feed downhill into the top chamber 32 via outlet channel 30. This geometry and behaviour is highly robust to minor deviations in execution, so it can easily be 3D printed and verified by the reader.

The performance of this device is analysed from an analytical, numerical, and experimental standpoint using 1 mm spheres as the particles. In the experimental case, 1 mm glass microspheres are used. More realistic scenarios are then investigated experimentally and discussed later, such as the uplift of natural materials (sharp sand, in various grade sizes) from a stationary hopper, as a proof-of-concept for drilling applications.

We now describe a 1-D analytical model of the experiment. The behaviour of the device can be simplified if only a single particle is considered, and any nominal energy lost in horizontal movement is disregarded. Then, using the equations of harmonic motion, the position, velocity, and acceleration histories of the pulse-elevator itself can be calculated. The acceleration of the device is zero as it rises through the neutral plane, but becomes negative thereafter. As it passes through -1 g, any particle within the device is assumed to become free-flying with the initial (still-upwards) velocity of the device at that instant, but a (downwards) acceleration due to gravity.

In the device frame, the particle must rise the ‘hop’ distance from one scoop to the next (10 mm, in the geometry tested). However, in the inertial frame, the particle need not climb so far because the device will move downwards on the next cycle, closing some of the gap. It is a simple matter to propagate the movement of the device and particle, in the time domain, to find the oscillation parameters which permit hopping. The maximum harmonic acceleration associated with those parameters is the limiting system excitation at which successful hopping of any particle is possible. We term this the ‘saturation’ excitation.

However, with multiple particles, the scoops are often approximately half-full. This means that any one particle on top of the others does not have to hop so high to make it into the next scoop, even if the particles below are left behind. If the lower 5mm of the scoop is already filled with material, then the minimum hop distance will be reduced to the outstanding 5mm, to make up the 10 mm total. We term the lower acceleration required to close this smaller gap the ‘activation’ excitation, because it marks the beginning of functionality.

An example is given in Fig. 2. In this case, the simulation time starts as the device moves upwards through the midpoint, with a particle at position 0 and the lip of the next scoop 0.01 m higher. This particle (red history) initially follows the harmonic motion of the device and moves with the lower scoop (green), but becomes free-flying at 0.007 s. The scoop immediately above (blue history) continues its harmonic motion, such that at 0.06 s, the near-hovering particle may be (just) caught by the rapidly descending scoop. This simulation does not, however, model the ‘capture’ event, so the red history continues under its own inertia. Clearly, some small horizontal movement would also be needed to make the capture in reality.

Although simplified, this model predicts the ‘activation’ acceleration where particles begin to climb through the device and the ‘saturation’ acceleration where each scoop can be fully emptied (assuming no adhesion in either case). These are given in Table 1 , and the values can be divided by g (gravity) to obtain the nondimensional relative acceleration F, if desired. Upon saturation, the limiting factor must move to the feeding or dumping channels instead. Table 1: Simulated Activation and Saturation Excitations

Frequency (Hz) 10 20 30 40 50

Activation acceleration (g) 1.9 3.3 5.2 7.6 10.9

Saturation acceleration (g) 2.4 4.8 8.2 13.1 19.4

From Table 1 , it can be seen that the activation acceleration needed to shift the particle upwards is higher at higher frequency in this model. At least in part, this is considered to be because the amplitude of vibration is lower at higher frequencies in this model.

The experiment was modelled using finite element modelling. The device may be simulated in finite element software (Abaqus-Simulia, Dassault Systemes, Velizy-Villacoublay, France). To examine the ‘activation’ and ‘saturation’ limits, two scenarios are investigated: the first is the analysis of a single particle at various frequencies and accelerations (Fig. 3), and the second considers that bottom half of the bottom scoop of the device is filled with particles, and then propagates the chaotic interactions between the particles and walls of the device. This is a more realistic model of the real world (Fig. 4).

To reduce computation time, 2-D models are used and only the 10 Hz case is considered. A gravity of 9.81 m/s ² is assigned (this is the value for g), and the device moves at various frequencies to create given sinusoidal accelerations in the vertical direction, with amplitude as a driven parameter. Interaction between the particles and against walls of the device has been assumed to be hard and frictionless. The surrounding structure has been modified for experimental purposes, as will be explained in a later section.

The single-particle model is excited at 1 g, 2 g, 3 g, 4 g, and 5 g, to find the saturation acceleration (where each particle must hop the full height of every scoop). According to Table 1 , climbing should begin to be seen after the 2 g case. The actual results, for one second of movement, are shown in Figs. 5-8. The images show the particle paths through the reciprocation mechanism from the starting position of the particle shown in Fig. 3. As will be understood, when the frequency is fixed and the vibration is assumed to be sinusoidal (simple harmonic motion), the amplitude is varied in order to set the required acceleration.

The results do indicate climbing in the 2 g case, which is moderately unexpected due to the analytical threshold being found at 2.4 g, but in a highly-chaotic system such as this energy can easily be accumulated over a few cycles and then expended in a single, larger movement. An examination of the trajectory suggests that this is one explanation for the unexpected result. Accordingly, using the more computationally expensive numerical techniques (as opposed to the analytical techniques), it was found that the device would start to work at 1 ,9g. In the experiments reported below, it was found that the device did not provide significant particle climbing at 1g, but did at 2g. These results are considered to be suitably consistent. Turning to the multi-particle simulations, we expect to see a slightly more consistent performance, due to the reduced hop height and averaging of chaos. This is presented in Figs. 9-13, by considering how many particles are found in each scoop, numbered from #1 at the bottom to #1 1 at the top, after different periods of time: 0 s of excitation (red), 0.3 s (orange), 0.6 s (green), and 0.9 s (blue).

It is immediately apparent that, as the acceleration is increased, the great bulk of the particles is more effectively moved towards the top of the pulse-elevator as time progresses. In fact, after one second, the pulse-elevator operating at 4 g was able to eject four particles past scoop #11 , and the pulse-elevator operating at 5 g was able to eject thirteen particles past scoop #11 and into free space. These systems would very likely have cleared all particles in a few more seconds, but the computational price of such modelling work would be excessive.

The performance of the 5 g elevator is shown separately, in Figs. 14-17, so that the movement can be better visualised over time from 0s to 0.9s. This time, rather than the particle paths being traced, the position of each particle at the relevant time is indicated. Accordingly, Fig. 13 corresponds to the four images in Figs. 14-17. It is apparent that a few particles initially leak backwards into the feeding chamber, but most of them eventually feed correctly. Meanwhile, the vast majority begin to climb the pulse-elevator and, by 0.9s, a large number of particles have already left the device via the spout at the right.

The geometry described above is next tested against a range of vibration amplitudes and frequencies, with the measured output being the mass flow rate through the device, using the arrangement in Fig. 18. The geometry used for the finite element modelling was 3-D printed to a depth of 18 mm, and then covered over with a transparent acrylic sheet so that the inside structure can still be seen.

The apparatus is similar to that shown in Fig. 3. Reciprocation mechanism 110 has granular material 112 placed in feed chamber 114, which feeds downhill via an inlet channel 1 16 to the first pocket in the pulseelevator geometry. The pulse-elevator geometry is defined by a sequence of pockets 118, arranged as previously described. From the top pocket the particles feed downhill a spout 132.

The reciprocation mechanism is mounted on a shaker 140 (Model-407, LTV LING ALTEC Ltd, Royston, England, UK), so that the required excitation can be applied using a signal generator (Agilent 33220A, Agilent Technologies, Santa Clara, CA, USA) (not shown) and a power amplifier (PA25E, Electrodynamic LDS, Hottinger Bruel & Kjaer, Denmark) (not shown). The particles expelled from spout 132 are directed by ramp 134 to container 136 placed on weighing scales 150. A little more than 50 grams of granular material (1 mm glass beads, illustrated by the dots in Fig. 18) is loaded into the chamber 114 which feeds the pulse-elevator.

There is a total climb distance of 87 mm from the base of the first scoop to the overtop into the dumping mechanism, from where the granular material moves by gravity-feed into the weighing scales such that the mass at any time dating from the experiment start can be measured. The experiments undertaken, with or without success, are shown in Table 2. The maximum accelerations applied ranged from 1 g to 25 g, and the frequencies ranged (as before) from 10 Hz to 50 Hz. The failed experiments in the upper right of the table were marked unsuccessful (X) due to their being no measurable output of grains (that is, the system was below the activation threshold), and the failed experiments in the bottom left were marked unsuccessful (X) because they required amplitudes beyond the operating range of the shaker.

The start point was taken to be the beginning of the excitation, with the first particles arriving in the scales a few moments later. The mass transferred by the successful experiments was recorded every five seconds, and is presented in Figs 19-23, where each data point is the average of three runs. Note the extraordinary linearity in the performance of the system.

Table 2: Experiments undertaken

These results can be used to validate the activation and saturation accelerations calculated in Table 1 , by setting lower and upper bounds equal to the experimental runs immediately before and immediately after the first example of either state. This is a coarse tool, given that the runs were widely spaced in g, but it is nonetheless informative. The results of this analysis are presented in Table 3.

Table 3: Validation of 1-D analytical model and experimental results

Frequency (Hz) 10 20 30 40 50

Activation 1-D analytic [g] 1.9 3.3 5.2 7.6 10.9

Act. expt, lower bound [g] 1 2 4 5 5

Act. expt, upper bound [g] 2 3 5 10 10

Saturation 1-D analytic [g] 2.4 4.8 8.2 13.1 19.4

Sat. expt, lower bound [g] 2 4 5 10 15

Sat. expt, upper bound [g] 3 5 10 15 20

As was noted previously, the high degree of chaos, the restricted number of runs, and the small number of particles that can be modelled makes it difficult to include the finite element data in this comparison. Nonetheless, both the activation and saturation states were found to be in the region of 2 g, and the multiparticle system performed slightly better at higher accelerations, as would be expected. Another way to examine the data is to plot the gradients of the linear trendlines presented in Figs. 19-23. This produces steady state performance metrics in grams per second, as shown in Fig. 24, where logarithmic trendlines have been applied. This can be considered to be a useful figure of merit. As before, the acceleration values can be divided by g to obtain the nondimensional relative acceleration F, if desired by the reader.

It is apparent that performance will improve with applied acceleration, but the rate of improvement will decline as the saturation acceleration approaches.

If the system is saturated, the apparent improvement in performance with higher frequency can be easily understood. Assuming loose random packing (56% volume fraction), glass spheres (2.5 gr./cm ³ ), and half-full scoops (the device has a depth of 18mm), it is apparent that each scoop can hold almost exactly 1 gr. of material. Therefore, if each scoop transferred all its contents on every cycle, we would expect to see pulse-elevator performance rising linearly with frequency: 10 gr./s, 20 gr./s, 30 gr./s; at 10 Hz, 20 Hz, 30 Hz, etc.

In the experiment, however, we do not see a linear relationship, but we must remember that the chamber can only feed the pulse-elevator through a narrow channel, and there are channels between the scoops as well. The performance of these channels will not increase with frequency, and so each scoop will presumably become starved of material in turn.

The experiments reported above are idealised: the test material is provided in a hopper, and it is composed of glass microspheres. In real applications, there may be no hopper and the material may be much less uniform.

A modified pulse-elevator is therefore designed, with a lower inlet that uplifts granular material directly from a container, and transfers it to a set of scales. This modified pulse-elevator is shown in Fig. 25. This comprises a reciprocation mechanism 210, intended to be operated with its lower tip 220 immersed in a container of particulate. In this experiment, the contained (not shown) was an approximately hemispherical container of diameter corresponding to six times the lateral width of the reciprocation mechanism 210. As the particulate, two grades of sharp sand were tested: a ‘coarse’ material that did not pass a 60-grit sieve, and a ‘fine’ material that passed a 60-grit sieve but not a 10O-grit sieve. As shown in Fig. 25, an intake 216 is provided near the bottom of the pulse-elevator (reciprocation mechanism 210). The intake 216 leads to an arrangement of pockets 218 as previously described. The top end of the reciprocation mechanism 210 has an attachment part 221 for attachment to an actuator to reciprocate the reciprocation mechanism 210.

These experiments were challenging. Sand can provide considerable resistance to motion, and this tends to impede the oscillations needed to operate the pulse-elevator. However, vibration can also fluidise sand, and this effect allows efficient operations provided that the fluidisation conditions (to permit vibration) align with the operating conditions (to permit uplift). Fluidisation is usually associated with high relative acceleration, again given by F. However, the system settings of the high acceleration runs that were used earlier in this disclosure were unable to deliver movement of the pulse-elevator, perhaps due to jamming (a topic discussed in the literature [8]). The runs conducted at 20 g (nominal) appeared to be most optimal in the experimental space considered, as shown in Table 4.

Table 4 shows the mass of material uplifted in 15 seconds of operation, using the system settings associated with certain frequencies and accelerations in free air. However, although the frequencies are given with high confidence, the actual accelerations were likely to be attenuated by the effects described above.

Table 4: Mass of sand (in grams) uplifted in 15 seconds

Acceleration seting [g] 10 20 30

Coarse material [10 Hz] . . .

Coarse material [20 Hz] - 22.6

Coarse material [30 Hz] - 12.2 11.5

Coarse material [40 Hz] . . .

Coarse material [50 Hz] . . .

Fine material [10 Hz] . . .

Fine material [20 Hz] - 32.3 10.3

Fine material [30 Hz] - 23.0 7.4

Fine material [40 Hz] . . .

Fine material [50 Hz] . . .

These experiments serve to demonstrate that real world granular materials can be directly uplifted by this device.

Although Tesla valves have been suggested as a vibration powered pump for liquid applications [9], we do not believe that they have been shown to work, in this way, with respect to solids. Such a structure could be incorporated into non-augering percussive drill bits, such as conceived in Fig. 26, which would rotate only quickly enough to distribute percussive impacts. This would greatly reduce the magnitude of the hardware required. Fig. 26 shows a schematic perspective cross sectional view of a distal part of a drill bit 310. The distal tip of the drill bit 310 includes a cutting blade 312 and the shank 314 of the drill bit is generally cylindrical and smooth with the exception of an inlet aperture 316 close to the distal tip which leads into a pulse-elevator geometry including an arrangement of pockets 318 as already described.

Operation of the drill bit causes the generation of particulate in the form of spoil, which is uplifted from the borehole formed by the drill bit along the pulse-elevator geometry. This is possible without gross rotation of the drill bit itself.

Other possibilities include metering (because there is essentially no fall-back when the device is switched off, the flow can be cycles on and off almost instantaneously); and horizontal transport, which is effective provided that the system is arranged to keep the exit port clear. Further embodiments of the invention will now be described, with reference to Figs. 27, 28 and 29.

Each of Figs. 27 and 29 shows a particulate transport apparatus 400 having different sequences of pockets arranged in series. In order to explain an embodiment of the invention corresponding to the third aspect, the sequence of pockets indicated by the dashed box in Fig. 27 is first described.

The apparatus 400 of Fig. 27 is arranged in repose lying on a surface and to that extent is not an illustration of the apparatus in use. The vertical axis is indicated as V and the horizontal axis is indicated as H. During use of the apparatus it is intended that the apparatus is arranged so that V is vertical and H is horizontal.

Considering the sequence of pockets indicated by the dashed box in Fig. 27, this is a reciprocation mechanism 402 having a first end 404 and a second end 406. The reciprocation mechanism comprises a sequence of pockets 408 arranged along a particulate transport path of the reciprocation mechanism. Each pocket is arranged so that, when the reciprocation mechanism is arranged in a substantially horizontal orientation and caused to reciprocate in a substantially vertical direction with a source of particulate at the first end 404 of the reciprocation mechanism, particulate is thrown from each pocket in the sequence to a respective next pocket in the sequence to effect an overall substantially horizontal particulate transport path towards the second end 406 of the reciprocation mechanism.

As shown in Fig. 27, the sequence of pockets in the dashed box has a principal axis X corresponding to the overall particulate transport path.

There is an array of pockets at one side of the principal axis X, designated as side A, and an array of pockets at the other side of the principal axis, designated as side B. It is therefore possible to designate pockets A and pockets B. Pockets A are arranged so that, when the reciprocation mechanism is oriented horizontally, pockets A are aligned along axis A which is substantially parallel to the principal axis X. Pockets B are arranged so that, when the reciprocation mechanism is oriented horizontally, pockets B are aligned along axis B which is substantially parallel to the principal axis X. Axis A and axis B are offset from each other, on opposing sides of the principal axis X.

Pockets A have a uniform pitch along axis A and pockets B have the same uniform pitch along axis B. The position of pockets A along axis A relative to the position of pockets B along axis B is staggered. Pockets A and pockets B open towards each other.

In order to operate the particulate transport apparatus to transport particulate, the reciprocation mechanism 402 is reciprocated in a substantially vertical direction with a source of particulate at the first end 404 of the reciprocation mechanism. The particulate is thrown from each pocket in the sequence to a respective next pocket in the sequence to effect an overall substantially horizontal particulate transport path towards the second end of the reciprocation mechanism. This is assisted by the shape of the pockets, as described in more detail below. In the reciprocation mechanism 402 shown in Fig. 27, when arranged substantially horizontally, pockets A are arranged below the principal axis X and pockets B are arranged above the principal axis X.

For the sake of ease of illustration, Fig. 28 shows an enlarged view of part of the reciprocation mechanism 402 close to the first end 404. Considering for example each pocket A, each such pocket has a rear wall 410 that is downwardly sloping with respect to the overall particulate transport path and a front wall 412 that is upwardly sloping with respect to the overall particulate transport path. The rear wall 410 is closer to the first end compared with the front wall 412. Similarly, the front wall 412 is closer to the second end compared with the rear wall 410.

Between the rear wall and front wall there is a base region 414. The base region 414 has a scoop shape. The rear wall 410, base region 414 and front wall 412 together have an overall curved shape.

Considering next each pocket B, each such pocket has a rear wall 420 that is upwardly sloping with respect to the overall particulate transport path and a front wall 422 that is downwardly sloping with respect to the overall particulate transport path. The rear wall 420 is closer to the first end compared with the front wall 422. Similarly, the front wall 422 is closer to the second end compared with the rear wall 420. Between the rear wall 420 and front wall 422 there is a base region 424. The base region 424 has a scoop shape.

The rear wall 420, base region 424 and front wall 422 together have an overall curved shape. It is intended that the shape of pockets A and B are substantially mirror images of each other, except for the staggered offset.

Considering the lowest position in the base region of pockets A and the highest position in the base region of pockets B, the staggered arrangement of pockets A and B is such that the highest position in the base region of one pocket B is arranged at a position that is half way between the lowest positions in the base regions of two adjacent pockets A, when considered along the principal axis X.

Considering the principal axis X, it is possible to consider the slope or average slope of the front and rear walls with respect to the principal axis. As shown in Fig. 28, the slope (or average slope) of each front wall 412, 422 is steeper than that of each rear wall 410, 420.

In operation of the particulate transport apparatus, particulate is thrown from a pocket A to hit the rear wall 420 of a corresponding pocket B to be deflected towards the second end and to be caught in a subsequent pocket A in the sequence of pockets. The front wall 422 of pocket B may act to deflect or direct the particular downwards into the subsequent pocket A.

It will be noted that the description of Figs. 27 and 28 refer only to a small part of the overall apparatus shown in Fig. 27. The overall apparatus is described now in more detail with respect to Fig. 29. The particulate transport apparatus 400 shown in Fig. 29 corresponds to that shown in Fig. 27 and the same vertical and horizontal directions apply. The particulate transport apparatus 400 has first section 430 that is a vertical particulate transport section, leading to second section 440 that is a horizontal particulate transport section, leading to third section 450 that is a vertical particulate transport section, leading to fourth section 460 that is a horizontal particulate transport section, leading to fifth section 470 that is a vertical particulate transport section, leading to sixth section 480 that is a horizontal particulate transport section, leading to seventh section 490 that is a vertical particulate transport section, leading to outlet chute 500.

In operation, the leading end 432 of the apparatus, e.g. in the form of a percussive drill, is inserted into a source of particulate. Particulate enters the apparatus at entrance 434.

The first section 430 that is a vertical particulate transport section therefore provides the upright sequence of pockets arranged along an upright particulate transport path of the reciprocation mechanism. Each pocket is arranged so that, when the upright sequence of pockets is arranged in an upright orientation and caused to reciprocate in a substantially vertical direction with the source of particulate at a lower end of the upright sequence of pockets, particulate is thrown from each pocket in the upright sequence to a respective next pocket in the upright sequence to effect an overall upright particulate transport path towards an upper end of the upright sequence of pockets.

The second section 440 is a substantially horizontal sequence of pockets, disposed in series with the upright sequence of pockets of the first section 43. The substantially horizontal sequence of pockets is arranged along a substantially horizontal particulate transport path of the reciprocation mechanism. Each pocket is arranged so that, when the substantially horizontal sequence of pockets is arranged in a substantially horizontal orientation and caused to reciprocate in a substantially vertical direction with a source of particulate at a first end of the substantially horizontal sequence of pockets, particulate is thrown from each pocket in the sequence to a respective next pocket in the sequence to effect an overall substantially horizontal particulate transport path towards a second end of the substantially horizontal sequence of pockets.

Accordingly, in use, particulate is transported from the upright sequence of pockets of the first section 430 to the substantially horizontal sequence of pockets of the second section 440 by said reciprocation.

Similar comments apply to the transition between the second section 440 and the third section 450. In this case, particulate is transported from the substantially horizontal sequence of pockets of the second section 440 to the upright sequence of pockets of the third section 450 by the same reciprocation.

As will be understood, the detail of the construction of the upright sections has been described with respect to the first aspect and the detail of the construction of the horizontal sections has been described with respect to Figs. 27 and 28. ***

The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means for example +/- 10%.

References

A number of publications are cited above in order to more fully describe and disclose the invention and the state of the art to which the invention pertains. Full citations for these references are provided below. The entirety of each of these references is incorporated herein. [1] K. Zacny and G. Cooper, “Methods for cuttings removal from holes drilled on Mars,” MARS The International Journal of Mars Science and Exploration, vol. 3, pp. 42-56, 2007.

[2] Y. Tian, P. Yuan, F. Yang, J. Gu, M. Chen, J. Tang, Y. Su, T. Ding, K. Zhang, and Q. Cheng, “Research on the principle of a New Flexible screw conveyor and its power consumption,” Applied Sciences, vol. 8, no. 7, 2018.

[3] M. Bortolamasi and J. Fottner, “Design and sizing of screw feeders,” International Congress for Particle Technology, Nuremberg, German, March, 2001.

[4] P. Owen and P. Cleary, “Prediction of screw conveyor performance using the Discrete Element Method (DEM),” Powder Technology, vol. 193, no. 3, pp. 274-288, 2009.

[5] E. Sloot and N. Kruyt, “Theoretical and experimental study of the transport of granular materials by inclined vibratory conveyors,” Powder Technology, vol. 87, no. 3, pp. 203-210, 1996.

[6] K. Zacny, M. Quayle, M. McFadden, A. Neugebauer, K. Huang, and G. Cooper, “A Novel Method for Cuttings Removal from Holes During Percussive Drilling on Mars,” Revolutionary Aerospace Systems Concepts - Academic Linkage (RASCAL), pp. 1-15, 2002.

[7] N. Tesla, US Patent 1 ,329,559, 1920.

[8] D. Firstbrook, “Ultrasonically assisted penetration through granular materials for planetary exploration”, PhD Theses, University of Glasgow, 2017.

[9] Q. M. Nguyen, J. Abouezzi, and L. Ristroph. “Early turbulence and pulsatile flows enhance diodicity of Tesla’s microfluidic valve”. Nat Commun 12, 2884, 2021.