Slurry pump

BACKGROUND OF THE INVENTION

The invention relates to a slurry pump, particularly for pumping abrasive slurries or construction slurries. Construction slurries are mixtures according to lime and/or cement-related recipes, such as cement mortar, concrete mortar containing hard pebbles, and Anhydrite(Gyvlon). Construction slurries are difficult to pump due to their viscous properties and abrasiveness.

A known slurry pump for concrete mortar comprises two pump cylinders that connect to a hopper for concrete mortar. The pump cylinders each comprise a mortar displacer, wherein the displacers alternately make a pressure stroke to push the mortar out of the pump cylinders. In the hopper a line is placed of which the inlet is always brought straight in front of the opening of the pump cylinder that is about to start the pressure stroke. When swinging said inlet, the mortar flow in the line comes to a standstill, after which the next pressure stroke brings it into motion again. This is called a pulse or pulsation in the mortar flow. Swinging the inlet causes a lot of noise, and the abrupt standstill of the mortar flow sometimes causes undesired Shockwaves in the mortar lines. On the other hand the pulsation can be used to drag the pouring hose filled with heavy mortar more easily over the floor.

Due to the weight of the concrete mortar the pulsation is accompanied by considerable loss of energy, particularly in case of higher heads of the concrete mortar. Furthermore the irregular mortar flow is disadvantageous in case of the continuous pouring of elongated

construction parts, such as driven piles, as in between each pulse the movement of the line above the mould needs to be interrupted. In case of fast-setting types of concrete, pulsations may even cause local compaction or clog-formation in the lines.

It is an object of the invention to provide a slurry pump that can be used in a versatile manner.

It is an object of the invention to provide an alternative slurry pump.

SUMMARY OF THE INVENTION

According to one aspect the invention provides a slurry pump, particularly for pumping abrasive slurries or construction slurries, comprising a frame, a rotor that is rotatably connected to the frame and which is provided with at least three pump cylinders each having a related hydraulic drive cylinder, wherein the drive cylinders comprise a piston and a piston rod that is connected to a slurry displacer in the pump cylinder for moving the slurry displacer by the pump cylinder, wherein the pump cylinders comprise cylinder openings which by rotation of the rotor can consecutively be placed in front of an inlet opening for receiving slurry during a suction stroke of the slurry displacer, and an outlet opening which in rotation direction is spaced apart from the slurry displacer for discharge of the slurry during a pressure stroke of the slurry displacer, wherein at least two successive cylinder openings in a certain rotation position of the rotor are at least partially jointly positioned in front of the outlet opening, and a hydraulic drive assembly for driving the drive cylinders, wherein the drive assembly comprises a rotation bearing with which the rotor is connected to the frame, wherein the rotation bearing comprises a retained bearing part that is connected to the frame, and a rotatable bearing part that is connected to the rotor, wherein the retained bearing part is provided with a hydraulic supply channel having a supply opening and the rotatable bearing part per hydraulic cylinder is provided with a hydraulic passage channel having a passage opening, wherein the supply opening and the passage openings each in rotation direction extend over only a part of a revolution, wherein the supply opening depending on the rotation position of the rotor hydraulically connects to

the passage opening related to the pump cylinder of which the cylinder opening is at least partially positioned in front of the outlet opening, wherein the retained bearing part is furthermore provided with a separate hydraulic pre-actuation channel having a pre-actuation opening which in rotation direction extends over only a part of a revolution and which depending on the rotation position of the rotor hydraulically connects to the passage opening related to the pump cylinder of which the cylinder opening is positioned between the inlet opening and the outlet opening, wherein a first supply of hydraulic drive fluid to the hydraulic supply channel and a second supply of hydraulic drive fluid to the pre-actuation channel can be separately activated.

The drive assembly is adapted for separately activating the first and second supply. In that way it is possible to adjust the parameters of the supply of hydraulic drive fluid during pre-actuating the pump cylinder, when the cylinder opening is still positioned between the inlet opening and the outlet opening, and the parameters of the supply of hydraulic drive fluid during discharging the slurry, when said pump cylinder with its cylinder opening is at least partially positioned in front of the outlet opening, to each other. Pre-actuation for instance makes it possible already prior to discharge, to bring the slurry at a pressure adapted to the pressure in the outgoing slurry flow, as a result of which a regular or low-pulse outgoing slurry flow can be generated.

In one embodiment the inlet opening and the outlet opening are formed in a head wall extending in front of the cylinder openings, wherein in the rotation direction the distance between the inlet opening and the outlet opening is sufficiently large for in a first rotation position of the rotor placing a cylinder opening fully aside the inlet opening and the outlet opening. The head wall is able to fully close off a filled pump cylinder to be pre-actuated, as a result of which only a slight movement of the slurry displacer is necessary for bringing the slurry at the wanted pressure.

In one embodiment a full rotation of the rotor constitutes 360 degrees, wherein the cylinder opening is closed off over a first rotation trajectory of 5-15 degrees. Pre-actuating the closed off pump cylinder can then take place during rotation of the rotor over the first rotation trajectory,

as a result of which the rotor is able rotate continuously. For that purpose the drive assembly may be adapted for providing the second supply when the rotor is in the first rotation position or goes through the first rotation trajectory.

In one embodiment the drive assembly is adapted for according to a pulse or thrust starting the second supply when the rotor is in the first rotation position or goes through the first rotation trajectory, and subsequently stopping the second supply. Pre-actuation thus takes place in a short space of time.

In one embodiment thereof the drive assembly is adapted for consecutive to starting the second supply, stopping the second supply within the first rotation trajectory. During the first rotation trajectory the slurry has been brought fully at the intended pressure, ready for after the first rotation trajectory being discharged via the outlet opening.

In one embodiment the drive assembly for the second supply comprises a hydraulic high-pressure pump which via a pre-actuation valve is connected to the pre-actuation channel, wherein the drive assembly preferably comprises a hydraulic accumulator between the high- pressure pump and the pre-actuation valve. A hydraulic accumulator is able to keep hydraulic drive fluid ready at operational pressure, as a result of which pre-actuation can take place thrust-wise while the high- pressure pump is subjected to slight peak load or no peak load at all.

The accumulator can be charged at a moment that is energetically advantageous to the high-pressure pump, when the drive assembly comprises an accumulator filling valve between the hydraulic high- pressure pump and the pre-actuation valve, wherein the hydraulic accumulator is accommodated between the accumulator filling valve and the pre-actuation valve.

Said refilling can take place very evenly when the accumulator filling valve in the opened condition is a pressure-compensated or steady flow valve.

Undesirable return of hydraulic drive fluid during pre-actuation in the direction of hydraulic components situated upstream of the accumulator can be counteracted when the drive assembly is adapted for closing the accumulator filling valve or keeping it in the closed condition when the pre-actuation valve is in the opened condition. This is particularly advantageous when the hydraulic high-pressure pump also ensures the second supply, which should take place evenly in order to discharge the slurry evenly during the pressure stroke.

In one embodiment the retained bearing part and the rotatable bearing part are positioned concentrically with respect to each other.

In one embodiment the pre-actuation opening is situated aside and/or spaced apart from the supply opening, so that pre-actuation and the subsequent actuation of the pressure stroke can take place within and aside the first rotation trajectory, respectively. In one embodiment the pre-actuation opening is therefore situated in operational rotation direction in front of the supply opening.

In one embodiment the passage openings are separated one from the other and are substantially evenly distributed in rotation direction, so that the pressure strokes for the consecutive pump cylinders are able to succeed each other evenly within a revolution.

In one development the piston divides the inside of the hydraulic drive cylinder into a piston rod side and a bottom side, wherein the passage channel per hydraulic drive cylinder connects to the bottom side. Due to the connection at the bottom side of all drive cylinders, per pump cylinder substantially the same quantity of drive fluid is necessary to make a pressure stroke.

When the piston rod sides are connected one to the other with a compensating transfer channel, said compensating transfer channel may ensure that during the pressure stroke of a pump cylinder in front of the outlet opening another pump cylinder makes a suction stroke in front of the inlet opening.

In one embodiment apart from being connected to the supply opening, the supply channel is also connected to the compensating transfer channel via a hydraulic rotary connection, wherein a fraction of the hydraulic drive fluid from the supply channel is provided to the compensating transfer channel. The fraction of hydraulic drive fluid enhances the suction strokes of the pump cylinders in addition to their drive via the pushing cylinder, as a result of which it is ensured that a suction stroke is finished completely even before the cylinder opening leaves the inlet opening.

In one embodiment thereof the supply channel is connected to the compensating transfer channel via a supply valve, wherein the supply valve in the opened condition is a pressure-compensated or steady flow valve. Enhancing the successive suction strokes then takes place without or with only slight influence on the flow rate to the pushing pump cylinder, as a result of which said pressure stroke can take place evenly.

The compensating transfer channel preferably per hydraulic drive cylinder, also connects via a one-way valve opening towards the compensating transfer channel, to a part of the inside of the hydraulic drive cylinder that is situated in the end range of a pressure stroke of the slurry displacer at the bottom side of the piston. This structure has the advantage that when the said pressure stroke has already been completed before the related suction stroke has been completed, the drive fluid passed to the pushing drive cylinder as yet reaches the hydraulic drive cylinder actuating the suction stroke, via the one-way valve.

Alternatively or additionally the passage channel per hydraulic drive cylinder, also connects via a one-way valve opening towards the passage channel, to a part of the inside of the hydraulic drive cylinder that is situated in the starting range of a pressure stroke of the slurry displacer at the piston rod side of the piston. Said one-way valve allows for the pushing hydraulic drive cylinder to reach its end stroke when the sucking hydraulic drive cylinder has already reached its end stroke.

In combination both one-way valves ensure per hydraulic drive cylinder that the drive cylinders on the rotor each reach their desired starting and end positions without having to stop the rotor. After all this would have the disadvantageous consequence of the slurry flow making an unexpected stop. The parts of the drive assembly on the rotor therefore are self-balancing.

In one embodiment the outlet opening is kidney-shaped having a contour which in rotation direction is substantially constant, wherein an outlet port connects to the outlet opening which extends over or spans the outlet opening from the contour in order to provide an internal outlet chamber above the outlet opening, wherein the inner height of the internal outlet chamber increases evenly or linearly in rotation direction in order to end as outlet. The connection of the internal outlet chamber to the contour of the outlet opening enhances the flow- through of the pushed out slurry from the outlet opening. Due to the constant contour of the outlet opening the pushed out slurry acquires a wanted directional component in the direction of the outlet over a large part of the tangential length of the outlet opening. The even increase of the inner height prevents slurry from being left behind in those parts of the outlet chamber situated farthest from the outlet.

In one embodiment the slurry displacer is built up with a sealing ring that seals against the inner wall of the pump cylinder, and a core positioned centrally with respect to the sealing ring, which core projects from the sealing ring in the pushing direction of the slurry displacer. The core weakens the centre of a clod of slurry residue left behind on the sealing ring. As a result it will break at the start of a suction stroke in order to mix again with the slurry. In a next pressure stroke said residue is then discharged via the outlet opening.

In one embodiment the inlet opening and the outlet opening are formed in a head wall extending in front of the cylinder openings, wherein in the end position of a pressure stroke the sealing ring is positioned at a short distance from the cylinder opening and the core is positioned inside the cylinder opening and at a short distance from the head wall. The head wall then thinly skims off the slurry residue left behind on the sealing ring just above the core in order to weaken it.

In one embodiment the core has a conically shaped distal end, for instance to force pebbles through the outlet opening as yet.

In one embodiment the drive assembly comprises a control for controlling the slurry pump according to drive parameters, wherein the control comprises input means for entering a pulse parameter for a pulse in the slurry flow to be discharged through the outlet opening, wherein the drive assembly is adapted for activating the first and second supply according to the drive parameters as a function of the pulse parameters entered.

In this case a pulse parameter is defined as the need for pulsation, the degree or intensity, and the moment or the number of pulses in the course of time, or per revolution or part of the revolution. Pulsation or a pulse is in that case defined as a short change of speed or thrust in the outgoing slurry flow.

The drive assembly of the slurry pump according to the invention is adapted for ensuring the drive according to the drive parameters as a function of the pulse parameters entered, as a result of which a pulse can be generated in the slurry flow when necessary. It is for instance possible to pump pulse-free in case of the continuous pouring of elongated objects, and pulsated for during pouring for instance a floor, being able to drag the pouring hose situated thereon.

When the input means are adapted for entering a pulse parameter, and the drive assembly is adapted for ensuring the drive in response according to the drive parameters as a function of the pulse parameters entered during pumping action of the slurry pump, a pulse-free mortar flow can be opted for for said pouring of the floor. Pulsation is then only activated every now and then, by adjusting the pulse need, for during pouring being able to drag the pouring hose more easily. After that the pulsation can be stopped.

In one embodiment the input means are adapted for manual control. The pulsation in the slurry flow can then be manually changed according to need and on site by the operator of the slurry pump.

When the input means are at least partially portable in a mobile manner and movable with respect to the frame, said operator is able to take along the input means to the location where it can best be seen what type of pulsation is wanted. This may for instance be seen at the end of a hose which discharges the slurry at a distance from the slurry pump.

The drive assembly is adapted for providing the first supply having a drive pressure and/or a drive flow rate as drive parameter.

In one embodiment the drive assembly is adapted for providing the second supply having a pre-actuation pressure and/or a pre-actuation flow rate as drive parameter. The slurry in the pump cylinder which moves with the cylinder opening towards the outlet opening, may as a result be brought at a known pre-pressure without it being able to leave the pump cylinder any more. The pressure difference between the slurry in the pre-actuated pump cylinder and the actual output-pressure in the slurry flow from the rotation-wise leading pump cylinder that still discharges to the outlet opening, thus can be managed, and as a result so is the degree of pulse in the outgoing slurry flow.

In that case the drive assembly preferably is adapted for ensuring driving according to one or more of the said drive parameters as a function of the pulse parameter entered. In that way the drive assembly, for instance from a constant starting operation, is able to effect the wanted pulse in response to the set pulse parameter.

In one embodiment the drive assembly is adapted for ensuring the pre- actuation pressure as a function of the drive pressure. In that way the said pressure difference in a constant starting operation in the successive pressure stoke transitions can be kept constant, and thus the size of the successive pulses in the slurry flow.

In one embodiment thereof the drive assembly is adapted for providing drive fluid with a pre-actuation pressure that substantially equals the drive pressure. As a result the said pressure difference is nil, because of

which the successive pressure strokes follow each other smoothly. The slurry flow is low-pulse or pulse-free as a result.

Alternatively or additionally the drive assembly is adapted for providing drive fluid with a pre-actuation pressure that is lower than the drive pressure. As a result the said pressure difference is negative, because of which a slight negative pulse or flow back in the outgoing slurry flow can be effected for instance to be able to drag a pouring hose.

Alternatively or additionally the drive assembly is adapted for providing drive fluid with a pre-actuation pressure that exceeds the drive pressure. Because of this said pressure difference is positive, as a result of which a slight positive pulse or flow acceleration in the outgoing slurry flow can be effected by injection of the pre-actuated slurry in the outgoing slurry flow. The injection can be used as an introduction of a stronger, negative pulse, so that the workmen know when they should jointly pull at the pouring hose. The higher pre-actuation pressure can also be used to compensate leakage losses in the hydraulic drive cylinders or the pump losses.

In one development the drive assembly is adapted for altering one or several drive parameters according to a predetermined function of the rotation position of the rotor with respect to the frame as a function of the pulse parameter entered. Due to these measures for instance the speed of a pressure stroke within said pressure stroke can be influenced, and thus achieving the end moment of the pressure stroke with respect to the rotation position. The rotation bearing may in that case accurately record the start of such a pressure stroke. When the pressure stroke is completed earlier than the next pump cylinder is able to start its pressure stroke, a pulse is created in the mortar flow.

In one development the drive assembly is adapted for rotation of the rotor with a rotation speed according to a predetermined function of the rotation position as a function of the pulse parameter entered. Due to these measures the cylinder openings are able to go through the trajectory between and aside the inlet opening and the outlet opening in an accelerated manner. The time that the pump cylinders are inactive is

thus shortened, as a result of which the flow rate of the outgoing slurry flow can be increased.

In an efficient embodiment thereof the slurry pump comprises a hydraulic rotation motor for rotation of the rotor, wherein the hydraulic drive is adapted for providing drive fluid to the hydraulic motor having a drive flow rate and/or a drive pressure as drive parameter, wherein the drive assembly is adapted for providing the drive fluid with a drive flow rate and/or a drive pressure to the rotation motor according to a predetermined function of the rotation position in response to the pulse parameter entered. In that case the rotation speed like the hydraulic cylinders can be ensured by the same hydraulic drive.

The pulse parameter entered can be continued until an alteration is necessary or wanted, when the control comprises a memory for the pulse parameter entered. The workman is then able to walk away from the input means in order to handle the pouring of slurry with two hands while the slurry pump pulsates or starts pulsating according to wish.

The input means preferably comprise an adjustment button, preferably a stepless adjustment button, and/or a stepless setting for entering the pulse parameter. It can easily be operated with one hand, so that during setting the workman is able to keep his other hand free.

From a further aspect the invention further provides a slurry pump, particularly for pumping abrasive slurries or construction slurries, comprising a frame, a driven rotor that is rotatably connected to the frame and which is provided with at least three pump cylinders each having a related hydraulic drive cylinder, wherein the drive cylinders comprise a piston and a piston rod that is connected to a slurry displacer in the pump cylinder for moving the slurry displacer by the pump cylinder, wherein the pump cylinders comprise cylinder openings which by rotation of the rotor can consecutively be placed in front of an inlet opening for receiving slurry during a suction stroke of the slurry displacer, and an outlet opening, which in rotation direction is spaced apart from the slurry displacer for discharge of the slurry during a pressure stroke of the slurry displacer, wherein the inlet opening and the outlet opening are formed in a head wall extending in front of the

cylinder openings, wherein the outlet opening is kidney-shaped having a contour which in rotation direction is substantially constant, wherein an outlet port connects to the outlet opening which extends over or spans the outlet opening from the contour in order to provide an internal outlet chamber above the outlet opening, wherein the inner height of the internal outlet chamber evenly increases in rotation direction in order to end as outlet.

The invention has the advantages and preferred embodiments as discussed above.

From a further aspect the invention furthermore provides a slurry pump, particularly for pumping abrasive slurries or construction slurries, comprising a frame, a driven rotor that is rotatably connected to the frame and which is provided with at least three pump cylinders each having a related hydraulic drive cylinder, wherein the drive cylinders comprise a piston and a piston rod that is connected to a slurry displacer in the pump cylinder for moving the slurry displacer by the pump cylinder, wherein the pump cylinders comprise cylinder openings which by rotation of the rotor can consecutively be placed in front of an inlet opening, for receiving slurry during a suction stroke of the slurry displacer, and an outlet opening, which in rotation direction is spaced apart from the slurry displacer for discharge of the slurry during a pressure stroke of the slurry displacer, wherein the inlet opening and the outlet opening are formed in a head wall extending in front of the cylinder openings, wherein the slurry displacer is built up with a sealing ring sealing against the inner wall of the pump cylinder, and a core positioned centrally with respect to the sealing ring, which core projects from the sealing ring in the pushing direction of the slurry displacer, wherein in the end position of a pressure stroke the sealing ring is positioned at a short distance from the cylinder opening and the core is positioned inside the cylinder opening at a short distance from the head wall.

The invention has the advantages and preferred embodiments as discussed above.

The aspects and measures described in this description and the claims of the application and/or shown in the drawings of this application may where possible also be used individually. Said individual aspects may be the subject of divisional patent applications relating thereto. This particularly applies to the measures and aspects that are described per se in the sub claims.

SHORT DESCRIPTION OF THE DRAWINGS

The invention will be elucidated on the basis of a number of exemplary embodiments shown in the attached drawings, in which:

Figure 1 shows an isometric front view of a slurry pump having a rotation bearing according to the invention;

Figure 2A shows the slurry pump according to figure 1 , wherein a part of the front side has been left out;

Figure 2B shows the slurry pump according to figure 2A, having an alternative outlet port;

Figure 3 shows the slurry pump according to figures 2A and 2B, further built out at the front side;

Figure 4 shows a longitudinal section of details of the slurry pump according to figure 3;

Figure 5 shows an isometric rear view of the slurry pump according to figure 1 ;

Figures 6A show an isometric front view of a first embodiment of the rotation bearing of the slurry pump according to figure 1 ;

Figures 6B and 6C shows a transparent isometric front view and a transparent side view of the core of the rotation bearing according to figure 6A;

Figure 6D shows a transparent isometric front view of the casing of the rotation bearing according to figure 6A;

Figure 7A shows an isometric front view of a second embodiment of the rotation bearing of the slurry pump according to figure 1 ;

Figures 7B and 7C show a transparent isometric front view and a transparent side view of the core of the rotation bearing according to figure 7A;

Figure 7D shows a cross-section of the rotation bearing according to view VII in figure 7A;

Figure 8 shows a first hydraulic schedule of the slurry pump according to the preceding figures; and

Figure 9 shows a second hydraulic schedule of the slurry pump according to the preceding figures.

DETAILED DESCRIPTION OF THE DRAWINGS

Figures 1 -3, 5 show a slurry pump 1 according to the invention suitable for pumping abrasive slurries or construction slurries.

The slurry pump 1 comprises a steady frame 2 and a rotor 20 that is rotatable about a horizontal axis of rotation S. At its front side the frame 2 is provided with a vertical head wall 3, to which at the upper side a hopper 10 is attached. The bottom side of the hopper 10 forms an inlet port 9 to a kidney-shaped inlet opening 1 1 in the head wall 3. Below the hopper 10 an outlet port 4 is provided extending from a kidney-shaped outlet opening 7 in the head wall 3. To the outlet port 4 a spout 5 is attached that can be hinged down and has a connection 6. The inlet opening 1 1 and the outlet opening 7 have the same contour, and are situated straight across each other with respect to the axis of rotation S. In the circumferential direction the distance of the curved side edges with respect to the axis of rotation S is constant.

By means of the frame 2 the slurry pump 1 can for instance be secured to the undercarriage of a slurry pump truck that is not shown, wherein a boom, hose or line can be connected to the connection 6 for pouring slurry introduced in direction A and discharged under increased pressure in direction B at the desired location.

As shown in figures 2A and 2B the rotor 20 comprises a cylindrical middle section 32 to which four pump cylinders 30a-d are attached that extend parallel and horizontal to each other. At the opposite side the pump cylinders 30a-d are attached against a wear disk 23 that is provided with four cylinder openings 31 a-d to the inside of the pump cylinders 30a-d. The pump cylinders 30a-d and the wear disk 23 are made of a hard metal, such as steel. The openings 31 a-d are arranged according to a notional circle having the axis of rotation S as a centre, and they are evenly distributed over it in circumferential direction.

At the opposite side of the middle section 32 four hydraulic drive cylinders 40a-d are attached. At their inner side the hydraulic cylinders 40a-d are each provided with a piston 41 a-d which by means of a piston rod 42a-d is connected to a slurry displacer 34a-d in each pump cylinder 30a-d. In figure 3 this is schematically shown for the fourth pump cylinder 30d only.

Figure 4 shows an embodiment of the slurry displacers 34a-d in detail, shown in the end position of a pressure stroke. The slurry displacers 34a-d comprise a cylindrical sealing ring holder 1 10 at the end of the piston rod 42a-d. Opposite the piston rod 42a-d, the sealing ring holder 1 10 comprises a sealing ring bush 1 1 1 extending through a sealing ring 1 12 of elastic material. At the front side the sealing ring 1 12 is provided with a projecting circumferential edge 1 13 which at the outside connects in a watertight manner to the inner wall of the pump cylinders 30a-d. The sealing ring 1 12 is confined by means of a metal cone 1 14 which is secured to the sealing ring bush 1 1 1 with a bolt 1 1 5. In the shown end position of the displacer 34a-d the circumferential edge 1 13 is positioned a few millimetres before the head wall 3, and the cone 1 14 extends through the cylinder opening 31 a-d in question, wherein the flattened distal head surface 1 16 is positioned a few millimetres before the continuation V of the front side

of the wear disk 23. The outer dimensions of the cone 1 14 and the sealing ring 1 12 are chosen such that the largest possible pebble 1 17 of the construction slurry to be pumped can be stored temporarily between a continuation V, the cone 1 14 and the sealing ring 1 12, as a result of which the pebble 1 17 present there cannot block the rotation of the rotor 20.

At the front side the rotor 20 is rotatably bearing-mounted with respect to the frame 2, wherein the wear disk 23 is positioned against the permanent head wall 3. The kidney-shaped openings 7, 1 1 in circumferential direction or rotation direction C have a length that is sufficient for in a certain rotation position of the rotor 20 placing two cylinder openings 31 a-d in the wear disk 23 that are consecutive in rotation direction, at least partially simultaneously in front of one of the kidney-shaped openings 7, 1 1 . The radial width of the kidney-shaped openings 7, 1 1 substantially equals the width of the cylinder openings 31 a-d in said width direction. The blind plate section 140 in the prolongations of the kidney-shaped openings 7, 1 1 is sufficiently large for fully closing off a revolving cylinder opening 31 a-d, in this example over a trajectory of approximately 10 degrees in case of a full revolution of 360 degrees. The cylinder opening 31 a-d is then fully closed off over a rotation trajectory of at least 3 degrees. In figure 3 the contour of the inlet opening 1 1 and the outlet opening 7 in the head wall 3 is projected in axial direction on the wear disk 23. This is shown by means of interrupted lines.

Figure 2B shows an alternative, substantially tangentially extending outlet port 4' with outlet opening 6'. The tangential outlet port 4' internally connects in a continuous manner to the kidney-shaped outlet opening 7, wherein in tangential direction towards the outlet opening 6', the axial height of the inner chamber evenly increases. At its lowest side, the tangential outlet port 4' may be provided with an inspection port that is not shown for inspecting or cleaning the inner chamber at that location.

As shown in figures 1 -3, 5 the rotor 20 is provided with a crown gear 22 on which two hydraulic motors 21 engage for rotation of the rotor 20 in operational direction C. As shown in figure 5 a rotor plate 49 is

attached against the bottom sides of the hydraulic cylinders 40a-d. In the middle the rotor plate 49 carries a rotor valve or rotation bearing 50 according to a first embodiment. The rotation bearing 50 is built up with a casing 51 and a core 52. The casing 51 is fixedly connected to the rotor plate 49, the core 52 is rotatably bearing-mounted within the casing 51 and connected to a swivelling arm 53 for swivelling the core 52 with respect to the frame 2 about its axis in direction D by means of a stepless adjustment 54. At the front sides the hydraulic cylinders 40a-d are connected one to the other by means of a compensating transfer channel 61 . The rear or bottom sides are individually connected to the rotation bearing 50 by means of drive lines 66a-d.

The rotation bearing 50 according to a first embodiment is shown in detail in figures 6A-D. The core 52 comprises a straight circle- cylindrical bearing part 55 with an accurately machined circumferential surface, which is accommodated under narrow tolerances in the casing 51 , and a wider end part 58 to which the swivelling arm 53 is attached. A supply line 80, a return line 81 , and a pre-actuation line 95, respectively, for hydraulic fluid are connected to the core 52. Said lines 80, 81 , 95 are shown in figure 5, and lead to a hydraulic control unit that is schematically shown in figures 8 or 9.

The supply line 80 to the core 52 is connected to an entry channel 82 in end part 58. Via a first blind longitudinal bore 83, the entry channel 82 is connected to a supply chamber 84 (in the claims the supply channel). In the longitudinal direction the supply chamber 84 is situated in the middle of the bearing part 55. At the radially opposite side of the supply chamber 84, the bearing part 55 is provided with two first compensation chambers 86 which via two first transverse bores 85 are connected to the first longitudinal bore 83. In radial direction the supply chamber 84 and the first compensation chambers 86 are outwardly opened in the direction of the casing 51 . In axial direction the first compensation chambers 86 are symmetrically situated on either side of the supply chamber 84.

The return line 81 of the core 52 is connected to a return channel 87 in the end part 58. Via a second blind longitudinal bore 88 the return channel 87 is connected to a return chamber 89 which in radial

direction is situated straight across the supply chamber 84. At the radially opposite side of the return chamber 89, the bearing part 55 is provided with two second compensation chambers 91 which via two second transverse bores 90 are connected to the second longitudinal bore 88. In radial direction the return chamber 89 and the second compensation chambers 91 are outwardly opened in the direction of the casing 51 . In axial direction the second compensation chambers 91 are also symmetrically situated on either side of the return chamber 89, straight across the first compensation chambers 86. In radial direction the supply chamber 84 and the return chamber 89 are situated straight across each other, that means with the centre at 180 degrees with respect to each other.

The pre-actuation line 95 to the core 52 is connected to a pre-actuation channel 96 (in the claims pre-actuation channel) in the end part 58. Via a third blind longitudinal bore 97 the pre-actuation channel 96 merges into a pre-actuation channel 98, which defines a pre-actuation opening 99 in the circumferential surface of the bearing part 55. The pre- actuation opening 99 in operational rotation direction C is situated at a short distance from the supply chamber 84, and in axial direction is situated in the middle of the supply chamber 84 and the return chamber 89.

The first compensation chambers 86 have a collective radially projected surface which as regards size substantially equals the radially projected surface of the supply chamber 84 and the pre-actuation opening 99 together. The second compensation chambers 91 have a collective radially projected surface which as regards size substantially equals the radially projected surface of the return chamber 89. The compensation chambers 86, 91 provide a radial counter force with respect to the supply chamber 84 and the pre-actuation opening, and the return chamber 89, respectively, when hydraulic fluid is pushed therethrough, so that wear of the casing 51 and the core 52 due to mutual surface contact is counteracted to a certain degree.

The casing 51 is provided with four passage channels 56a-d distributed evenly all round in circumferential direction, to which channels the drive lines 66a-d are connected. The passage channels 56a-d end with bowl-

shaped passage chambers 56a-d which are situated at the inner side of the casing 51 , recessed with respect to the accurately machined internal casing surface 59 which under narrow tolerances abuts the bearing part 55 of the core 52. The casing 51 is furthermore provided with four annular chambers 60 (in figure 6C only one can be seen) positioned recessed with respect to the internal casing surface 59, in which annular chambers circumferential gaskets are accommodated. Said gaskets engage onto the bearing part 55, on either side of the supply chamber 84 and discharge chamber 89, and on either side of the compensation chambers 86, 91 to prevent hydraulic fluid from axially flowing away unwantedly.

Figures 7A-D show a second embodiment of the rotation bearing 50', comprising an alternative core 52'. In figures 6A-7D the same parts are provided with the same reference numbers, and below only the differing parts are discussed. In its head surface, the alternative core 52' has an extra line connection 1 30 that connects eccentrically to the first blind longitudinal bore 83 via a fourth blind longitudinal bore 131 . On the rotor 20, the line connection 130 is connected to the compensating transfer channel 61 via a hydraulic rotary connection that is not shown, a one-way valve (137), a pressure-compensated or steady flow valve (132) and a coupling line (133). The alternative pre- actuation opening 99 is widened by means of an elongated chamber 134 extending in axial direction.

The hydraulics of the slurry pump 1 are schematically shown in figure 8 by means of the first embodiment of the rotation bearing 50. The slurry pump 1 comprises a reservoir 70 for hydraulic fluid, and a high-pressure pump 71 supplying hydraulic fluid under high pressure to a hydraulic control unit 72 connected to the frame 2.

The hydraulic control unit 72 comprises a first regulating valve 73 for supplying hydraulic fluid to the supply line 80, a second regulating valve 74 (in the claims pre-actuation valve) for supplying hydraulic fluid to the pre-actuation line 95, and a third regulating valve for supplying hydraulic fluid to the hydraulic motors 21 . The regulating valves 73, 74, 75 are connected to an electronic control 76 that may be provided with input means for manually entering pulsation parameters. Said

pulsation parameters relate to the need for pulsation, the degree or intensity, and the moment of the pulses in the course of time, or per revolution or part of a revolution. Pulsation or a pulse is in this case defined as a short speed change or thrust in the outgoing slurry flow. The control 76 may be provided with an adjustment button 77 discussed further below, for entering the pulse intensity.

The electronic control 76 in this example communicates wirelessly with a remote control 78 which can be taken along by a workman to the location where the slurry is poured, for instance in a building whereas the slurry pump 1 itself sits outside. Said remote control 78 may also be provided with input means for manually entering pulsation parameters. In this example the remote control 76 is provided with the adjustment button 77 discussed further below, for entering the pulse intensity, and with an adjustment button 78 for timing the pulses.

At the bottom side facing away from the piston rod 42, the hydraulic drive cylinders 40a-d comprise an entrance 67a-d which is connected to the individual drive lines 66a-d to the rotation bearing 50. Via a first threshold-bypass valve 69a-d operating as one-way valve, the drive lines 66a-d are furthermore connected to a bypass exit 68a-d. The bypass exit 68a-d is arranged such in the cylinder wall that in the ultimate retracted bottom position of the piston 41 a-d it is in connection with the space at the piston rod side of the piston 41 a-d. Each first threshold-bypass valve 69a-d blocks a fluid flow from the drive line 66a-d to the bypass exit 68a-d, but allows a threshold-bypass of hydraulic fluid from the drive cylinder 40a-d to the drive line 66a-d. The position of the bypass exit 69 with respect to the piston stroke is indicated by an interrupted line.

At the head side situated at the piston rod, the hydraulic drive cylinders 40a-d comprise an exit 62a-d with which the drive cylinder 40a-d is connected to the common compensating transfer channel 61 . Via second threshold-bypass valves 64a-d operating as a one-way valve, the compensating transfer channel 61 is furthermore connected to bypass entrances 63a-d in the drive cylinders 40a-d. The bypass entrances 63a-d are arranged such in the cylinder wall that in the ultimate extended head position of the piston 41 a-d, it is in connection

with the space behind the bottom side of the piston 41 a-d facing away from the piston rod 42a-d. Each second threshold-bypass valve 64a-d blocks a fluid flow from the compensating transfer channel 61 to the bypass entrance 63a-d, yet allows a threshold-bypass of hydraulic fluid from the drive cylinder 40a-d to the compensating transfer channel 61 . The position of the bypass entrance 63 with respect to the piston stroke is indicated by an interrupted line.

Figure 9 shows the hydraulics of the slurry pump 1 with the second embodiment of the rotation bearing 50', and apart from that, an alternative hydraulic control unit 72'. In figures 8 and 9 the same parts are provided with the same reference numbers and below only the differing parts are discussed. The alternative control unit 72' comprises a second valve 74' in front of the pre-actuation channel 95, which valve may be designed as regulating valve or as an on/off valve. Between the high-pressure pump 71 and the second valve 74' (in the claims pre-actuation valve) a fourth valve 135 (in the claims accumulator filling valve) is accommodated which is pressure- compensated or steady flow. Between the second valve 74' and the fourth valve 135 a hydraulic accumulator 136 is accommodated.

When making the slurry pump 1 operational, the high-pressure pump 71 is activated, after which the electronic control 76 activates the third regulating valve 75 in order to let the hydraulic motors 21 run with a constant speed of revolution, as a result of which the rotor 20 starts rotating at a constant speed of revolutions in operational direction C, approximately 10 revolutions a minute. The control 76 furthermore activates the first regulating valve 73 and the second regulating valve 74 to provide fluid to the supply chamber 84 and the pre-actuation channel 98, respectively, in the core 52 of the rotation bearing 50, with in this first example the same pressure. Concrete mortar is constantly poured in direction A into the hopper 10.

Figures 8 and 9 show the positions of the displacers 34 in the pump cylinders 30a-d at about the rotation position of the rotor 20 as substantially shown in figure 1 -3, 5. In this position the cylinder openings 31 a, 31 b of the first and second pump cylinders 30a, 30b respectively, are at least partially positioned in front of the kidney-

shaped outlet opening 7 to discharge mortar to the outlet port 4. The first pump cylinder 30a has discharged a large part of its mortar, the second pump cylinder 30b is about to start discharging. The cylinder openings 31 c, 31 d of the third and fourth pump cylinder 30c, 3Od, respectively, are positioned in front of the kidney-shaped inlet opening 1 1 for receiving mortar from the hopper 10. The third pump cylinder 30a is partially filled, the fourth pump cylinder 3Od is about to start receiving mortar.

In the rotation position of the passage chambers 57a-d coupled to the rotation position of the pump cylinders 30a-d as shown according to figure 7, the first passage chamber 57a, which via the first drive line 66a is in connection with the first hydraulic drive cylinder 40a, is still partially positioned in front of the supply chamber 84, as a result of which hydraulic fluid flows in direction K to the first hydraulic drive cylinder 40a. As a result the first pump cylinder 30a discharges mortar in direction H until the end position of the first hydraulic drive cylinder 40a is reached. Simultaneously the third passage chamber 57c, which via the third drive line 66c is in connection with the third hydraulic drive cylinder 40c, is positioned in front of the return chamber 89. As a result it is only allowed for the third hydraulic drive cylinder to make a return stroke to let the third pump cylinder 30c receive mortar in direction F. The return stroke of the third hydraulic cylinder 30c is powered by hydraulic fluid which via the compensating transfer channel 61 flows from the piston rod side of the first hydraulic cylinder 40a via the exits 62a and 62c in direction L1 to the piston rod side of the third hydraulic cylinder 40c. The hydraulic fluid at the opposite side of the piston 41 c is guided back to the return chamber 89 in the direction M1 via the third drive line 66c.

Should for whatever reason the first hydraulic drive cylinder 40a already have reached its end position whereas the third hydraulic cylinder 40c is still in the process of its return stroke, then the hydraulic fluid is able to escape via the first bypass exit 63a because the piston 41 a has passed the bypass exit 63a, as a result of which the supply of hydraulic fluid in direction K and L2 may continue in order to power the return stroke of the third hydraulic drive cylinder 40a up to the end position. The other way round, should the third hydraulic drive

cylinder 40c already have completed its return stroke whereas the pressure stroke of the first hydraulic drive cylinder 40a is still running, hydraulic fluid is able to escape via the third bypass exit 69c because the piston 41 c has passed the bypass exit 69c, as a result of which hydraulic fluid flows back in direction M2 to the return chamber 89 in order to have the first hydraulic drive cylinder 30a reach its end position. Due to this compensating transfer provision, per drive stroke, powered from a drive line 66a-d, an end position in the drive cylinders 40a-d in question is reached at all times.

When the second embodiment of the rotation bearing 50' and the coupling line 133 are applied, a flow of hydraulic fluid is continuously flowing via the pressure-compensated valve 132 to the compensating transfer channel 61 . Its flow rate is lower than the flow rate in the drive lines 66a-d. Said extra supply via the compensating transfer channel 61 ensures that the return strokes run faster than the pressure strokes. In this example the third pump cylinder 30c reaches its lowest point already before the cylinder opening 30c has reached the end of the inlet opening 1 1 . Due to the pressure-compensated valve 132, the pressure in the compensating transfer channel 61 is lower than in the drive lines 66a-d to such an extent that the pressure strokes are not hindered, as a result of which the return strokes are powered from the pushing hydraulic cylinder 40a-d and by the hydraulic fluid passing the pressure-compensated valve 132. The one-way valve 137 ensures that the hydraulic fluid cannot flow back, for instance when the supply and the return of the hydraulic fluid over the supply line 80 and the return line 81 are temporarily reversed for reversing the pumping action, for instance when the slurry. pump 1 is flushed with water after use.

In the rotation position of the pump cylinders 30a-d as shown according to figures 8 and 9, the second passage chamber 57b, which via the second drive line 66b is in connection with the second hydraulic drive cylinder 40b, is already positioned in front of the pre-actuation opening 99. As a result the hydraulic fluid has been passed in direction J to the second hydraulic cylinder 40b, and said cylinder 40b has been actuated in direction G during the rotation trajectory of the opening 66b in the direction of the kidney-shaped outlet opening 7, wherein the latter was closed off by the blind plate section 140 (in figure 2 the pre-

actuation trajectory is shown with interrupted direction G). As a result the mortar has been brought at discharge pressure without it being able to move through the opening 66b and the outlet opening 7. Optionally during pre-actuation, hydraulic fluid is transferred from the second hydraulic drive cylinder 40b in direction N to the third drive cylinder 40b, so that a part of its return stroke can thus be actuated.

In the rotation position of the pump cylinders 30a-d as shown according to figures 8 and 9, the fourth passage chamber 57d, which via the fourth drive line 66d is in connection with the fourth hydraulic cylinder 40c, is positioned aside the supply chamber 84, the return chamber 89 and the pre-actuation opening 99, as a result of which the operation of the fourth pump cylinder 3Od is hydraulically blocked.

By means of the stepless adjustment 54 the core 52 is set once in direction D such that the leading side of the passage chamber 57a-d is in flow-through connection with the supply chamber 84 when the leading side of the cylinder opening 31 a-d of the pump cylinder 30a-d actuated by it, is in flow-through connection with the kidney-shaped outlet opening 7.

In a continuation of a quarter of a rotation of the rotor 20 from the rotation position discussed, the first passage chamber 57a will finally be positioned aside the supply chamber 84, as a result of which the end position of the first hydraulic drive cylinder 40a is blocked. The emptied first pump cylinder 30a will move inactively with the cylinder opening 31 a towards the kidney-shaped inlet opening 1 1 . The second passage chamber 57b will be positioned in front of the supply chamber 84 and the cylinder opening 31 b will be positioned in front of the kidney-shaped outlet opening 7, as a result of which the already pressurised mortar in the second pump cylinder 30b is driven out of the pump cylinder by the pre-actuated second hydraulic drive cylinder 40b (as was indicated with direction (G) with the first pump cylinder 30a). Said pressure stroke smoothly follows the end of the pressure stroke of the first pump cylinder 30a, as a result of which a pulse-free outflow of mortar in direction B from the connection 6 is obtained. The third passage chamber 57c will be positioned in front of the pre-actuation exit 99, as a result of which the pressure in the filled third pump

cylinder 30c is increased (as was indicated with the second pump cylinder 30b). The fourth passage chamber 57d will be positioned in front of the return chamber 89, as a result of which the fourth pump cylinder 30d starts to receive mortar (as was indicated with the third pump cylinder 30c). The operation discussed above repeats itself per quarter of a revolution of the rotor 20, as a result of which from the transitions of the pressure strokes in the successive pump cylinders 30a-d a continuous, pulse-free mortar flow from the spout 5 is obtained.

The rotation trajectory in which the cylinder openings 31 a-d of the filled pump cylinders 30a-d, in this example the cylinder opening 31 b of the second pump cylinder 30b, are positioned fully blind or closed off behind the plate section 140 between the inlet opening 1 1 and the outlet opening 7 is small, in this example approximately 10 degrees. The temporary supply of hydraulic fluid for pre-actuation may in case of an undersized high-pressure pump 71 result in the pressure stroke of the leading pump cylinder 30a-d, in this example the first pump cylinder 30a, being subjected to an interruption. For that purpose the accumulator 136 is accommodated in the alternative hydraulic control unit 72'. The second valve 74' in that case only opens thrust-wise when the pump cylinder 30a-d to be pre-actuated runs through the fully blind trajectory behind the blind plate section 140 over less than three degrees. The thrust is powered by the pressurised hydraulic fluid in the accumulator 136, which in the remaining part of the quarter of a revolution prior to the thrust is evenly filled via the pressure- compensated or steady flow fourth valve 135. During the thrust, the fourth valve 135 is closed in order to counteract the hydraulic fluid flowing back thrust-wise in the direction of the first valve 73. By means of evenly filling and during the thrust closing off the fourth valve 135, a pressure stroke carried out simultaneously by a leading pump cylinder 30a-d is not affected. The thrust-wise pre-actuation may take place with an end pressure that is sufficiently high for for instance being able to compensate leakage losses in the mortar between the blind plate section 140 and the cylinder opening 31 a-d, as a result of which the pre-actuated pump cylinder 30a-d finally opens in the outlet opening 7 with the actual pressure over there. Said pre-actuation pressure is for instance 20% higher than the pressure in the drive line 80.

During the pumping action the substantially tangentially extending outlet port 4' has the advantage that the slurry ejected in front of the outlet opening 7 during the trajectory of the cylinder opening 31 a-d, acquires a tangential directional component that is preserved within the outlet port 4' that is curved similarly thereto, until the slurry leaves the outlet port 4' via the connection 6'. This enhances a constant flow- through of the entire slurry column present in the inner chamber, as a result of which accumulations are counteracted. The increasing radial height of the inner chamber ensures that also at the lowest start of the inner chamber slurry cannot remain stagnant. The slurry residue left within the pump cylinders 30a-d and the cylinder openings 31 a-d at the end of a pressure stroke, is then situated in the annular space bounded by the sealing ring 1 12 and the cone 1 14. During rotation of the cylinder opening 31 a-d behind the blind plate section 140 of the wear disk 23 said residue is skimmed, wherein the distal head surface 1 16 is a few millimetres from the wear disk 23. Pebbles 1 17 that may be present when skimming, will be urged to the position as shown in figure 4 in order to be temporarily stored, so that they will get out of each other's projection of the cylinder opening 31 a-d and do not block the outlet opening 7. Due to the cone 1 14 the core of the clod-shaped residue becomes weak, as a result of which the residue loses its acquired cohesion during the return stroke, after which its mixes again with the slurry received and is as yet pushed out at the next pressure stroke. It is thus counteracted that a permanent clod of slurry that may harden is left behind.

When during rotation operation, pulsation of a certain intensity in the outgoing mortar flow is desired, this can be set using the input means, such as the turning button 77 on the remote control 78. Several forms of pulsation are possible. The hydraulic control unit 72 is able to effect the following types of pulsation in the following manners:

First of all the control unit 76 is able to activate the second regulating valve 74 to provide hydraulic fluid to the pre-actuation line 95 with a pressure that is lower than the pressure in the supply line 80. In that case the pressure is inversely proportionate to the intensity set. In the ultimate position the supply to the pre-actuation line is fully stopped.

The mortar in the second pump cylinder 30b described in figure 7, as a result receives less or no pre-pressure, due to which when the second opening 31 b is released in front of the kidney-shaped outlet opening 7 the mortar that is already present there partially returns at higher pressure in the second pump cylinder 30b. As a result a negative pressure pulse in the outgoing mortar flow with the set intensity is created.

Second of all the control unit 76 may activate the second regulating valve 74 to provide hydraulic fluid to the pre-actuation line with a pressure that is higher than the pressure in the supply line 80. The mortar in the second pump cylinder 30b described in figure 7 as a result acquires an increased pre-pressure, higher than the 20% of the pressure in the supply line 80, as a result of which at releasing the second opening 31 b in front of the kidney-shaped outlet opening 7 a part of the content of the second pump cylinder is forcefully injected into the spout 5. This results in a positive pressure pulse in the outgoing mortar flow with the set intensity.

The said pre-actuation of the second valve 74, 74' can be made a function of the rotation position of the rotor 20, wherein the control unit 72, 72' for instance gets a feedback from a rotation position reader. In that case for instance a pulse can be generated in the mortar flow only once per revolution. Alternatively the said pre-actuation can be made a function of a period of time passed, or be activated only once when it is necessary. In these cases a pulse can be generated in the mortar flow at regular intervals or only once, respectively, so that the mortar hose can be dragged away regularly or at a wanted moment.

The wanted activation can be entered on site using the input means, for instance button 79 on the remote control 78 which an operator carries with him at the end of the mortar hose.

Thirdly the speed of revolution of the rotor within one revolution or a quarter thereof can be varied, preferably repeatedly. As a result the release of the second opening 31 b described in the example can take place prior to or after the pressure stroke of the first pump cylinder 30a

is completely finished. This can take place independent of the activation of the second valve 74, 74' to the pre-actuation channel 98.

Fourthly the supply of the hydraulic fluid to the supply chamber 84, and the discharge of hydraulic fluid via the return chamber 89 during rotation operation can be temporarily stopped and reversed, so that the pumping action with respect to the kidney-shaped inlet opening 1 1 and outlet opening 7 is reversed. In that way obstructions can be dealt with or the pump 1 can be rinsed.

The above description is included to illustrate the operation of preferred embodiments of the invention and not to limit the scope of the invention. Starting from the above explanation many variations that fall within the spirit and scope of the present invention will be evident to an expert.

(octrooi/184143/PCTP184143A des FG/NG 10130)