The invention relates to a compressor and a process for compressing a fluid. BACKGROUND

Compressors are generally known for compressing a fluid, such as a gas like air.In conventional compressors, an amount of fluid is directed into a storage tank, during which the pressure of the fluid in the tank increases while the volume of the tank remains essentially constant. The compressed fluid can then be used for various purposes, e.g. to inflate a vehicle tyre, to power pneumatic tools, in ventilation systems, in cooling systems, and in spraying applications such as air brushes or paint sprayers.

Conventional compressors have various drawbacks. For example, they produce a lot of noise during use, which can be a nuisance or lead to hearing damage. In addition, conventional compressors are susceptible to wear, causing them to malfunction over time and require costly, complex repairs. S ^UMMARY

An important object of the present invention is to provide an improved compressor, which at least partially removes at least one of the above drawbacks of conventional compressors. Another object of the information is to provide a relatively simple compressor which is less susceptible to wear and which produces relatively littlenoise.

For the purpose of these objects, the present invention provides a compressor for compressing a fluid. This fluid is particularly a gas, such as air.

The compressor comprises at least one hollow cylinder. The cylinder extends along its longitudinal axis between two cylinder ends. The cylinder comprises a hollowchamber, in which a piston is mounted. Said piston can extend along the longitudinal axis of the cylinder. The piston separates the cylinder chamber into two subchambers, each adjacent to one, but not the same, of the two cylinder ends. The two subchambers each have a respective volume that depends on the position of the piston on the longitudinal axis of the cylinder.

Preferably at least one, and preferably each of the cylinder ends is provided with a separate inlet for fluid to enter the cylinder chamber and a separate outlet to guide thefluid out of the cylinder chamber to an external tank. Said inlet and outlet are each preferably provided with a non-return valve to prevent the backflow of fluid.

The cylinder can be rotated about a rotation axis for the purpose of the displacement of the piston by gravity, in particular to direct a fluid situated in the cylinder chamber into a tank through an outlet under the influence of the weight of thepiston. The rotation axis encloses an angle with the cylinder axis.

Optionally, the compressor comprises a turning mechanism designed for the purpose of rotating the cylinder about the axis of rotation.

By rotating the cylinder this way, e.g. back and forth or unidirectionally, the piston in the cylinder chamber can be moved reciprocally between the cylinder ends.When the piston is moved away from a cylinder end, fluid is thereby sucked into the adjacent subchambers, through the corresponding inlet). When the piston is then moved toward the same cylinder end, the fluid pressure in the subchambers is increased, forcing the fluid to exit the cylinder through the corresponding outlet. The non-return valves prevent fluid from being sucked into the cylinder through the outletand from exiting the cylinder through the inlet. Thus, with each stroke, fluid is simultaneously sucked into one subchamber and forced out of the other. When the cylinder is rotated to ensure that the piston continuously moves reciprocally between the cylinder ends, the compressor can compress fluid and discharge it to a tank in a continuous cycle.

The fluid pressure thus built up in the tank is automatically limited by the compressor through the weight of the piston: as the tank pressure increases, the piston will automatically move less far to either end of the cylinder, until a pressure

equilibrium is reached after which the buildup of pressure will cease. The weight of the piston can be selected depending on the desired maximum tank pressure. As a result,the compressor is particularly easy and safe to use, and dangerous situations caused by excessive fluid pressure can be prevented automatically.

This provides an improved compressor with a relatively simple design. Due to the simultaneous suction and compression, the compressor is relatively efficient, allowing relatively high fluid pressure to be built up with relatively few strokes. Due to this efficiency and the relatively small number of moving parts the compressor is less susceptible to wear and produces relatively little noise during operation. The

compressor can be used for many applications, including the applications mentioned in the background section of the present document.

Optionally, the angle enclosed between the rotation axis and the longitudinal axis of the cylinder should remain between 30 and 150 degrees, preferably between 45 and 135 degrees, more preferably between 70 and 110 degrees, and yet more preferablybetween 80 and 100 degrees, e.g. approximately 90 degrees.

Optionally, the compressor can be designed to ensure that the rotation axis remains on the same horizontal plane during use. The compressor may comprise a support device for this purpose.

This makes it possible to mainly rotate the longitudinal axis of the cylinderwithin a vertical plane, whereby the effects of gravity on the device will be particularly favourable.

Optionally, the piston may have an adjustable piston mass, with at least two different values.

It may be made possible to reduce the piston mass when the compressor has tobe moved, for instance. Depending on the desired fluid pressure in the tank, the piston mass may be increased: a higher final pressure can be achieved with a greater piston mass. Piston mass can be adjusted in multiple ways, for instance by supplying or discharging water, or adding or removing granules made of lead and/or some other material with a relatively high density to or from the piston. Alternatively, a modularpiston may be used, consisting of relatively heavy piston parts, e.g. a stack of concentric discs.

Optionally, part of the cylinder could be removed from the cylinder to provide access to the cylinder chamber to adjust the piston mass. The detachable and

reattachable part of the cylinder may comprise of one of the cylinder ends or partthereof, for instance. One of the cylinder ends can, for instance, be connected to the cylinder via screw thread.

Optionally, the compressor can comprise the tank, with the tank being connected to at least one and preferably each of the outlets of the cylinder ends for the sake of fluid transfer.

Optionally, the compressor can be designed to have the tank rotate along with the cylinder. In this case, the tank is preferably connected to the cylinder by means of afixed, non-individually rotating connection.

The tank can be integrated with the entire cylinder or part thereof, or surround the cylinder or part thereof. The storage tank can have a rounded, e.g. circular, exterior, such as a circular-cylindrical outer wall. This provides a particularly compact and robust compressor.

Optionally, at least one, but preferably each, of the outlets features a hose coupling and/or swivel joint to provide a flexible fluid connection between the outlet and the storage tank.

This makes it possible for the cylinder to rotate while the tank remains stationary.

Optionally, the compressor can be equipped with a drive mechanism to drive the rotation of the cylinder.

Optionally, the drive mechanism can comprise a motor, e.g. an electric motor. Optionally, the drive mechanism can be designed to feature a manual drive mechanism, such as a crank handle or and/or a handle.

Optionally, the cylinder and/or piston can be fitted with a magnetic actuator designed to move the piston along the longitudinal axis of the cylinder under the influence of a magnetic force in relation to the cylinder, for example before, during and/or after rotation.

This magnetic actuator can also drive the reciprocating movement of the pistonin the cylinder chamber. The magnetic actuator includes, for example, an electromagnet, a permanent magnet and/or a ferromagnetic element.

The invention also provides a method for the compression of a fluid, which involves the piston cylinder assembly being moved, for example rotated, so that the piston, under the influence of its weight, compresses the fluid contained in the cylinderand, for example, directs it to a tank.

This working method has several advantages, as specified above.

Optionally, the method can include providing a compressor as described here. The method then comprises rotating the cylinder about the axis of rotation, during which the compressor is subjected to gravity, provided that at least the cylinder is supported, moving the piston along the longitudinal axis of the cylinder.

Optionally, the method can include adjustments to the piston mass of the piston,especially prior to rotating the cylinder.

Optionally, the method can include the magnetic actuation of the piston in relation to the cylinder, e.g. before, during and/or after rotation. FULL DESCRIPTION

In the following, the invention is further explained on the basis of embodiments and drawings. The drawings are schematic and show only examples of use cases.

Corresponding elements shall be indicated in the drawings with corresponding references. In the drawings:

Fig.1 is a cross-sectional view of a compressor according to one embodiment; Fig.2A-L is a cross-sectional view of the compressor of Fig.1 in several consecutive rotary positions; and

Fig.3 and 4 relate to an aspect described further on in the description. Fig.1 shows a compressor 1 for compressing a fluid, in particular a gas.

Compressor 1 comprises a hollow cylinder 2 extending along the longitudinal axis C of a cylinder between two cylinder ends 3a, 3b and bounding a cylinder chamber B.

The cylinder chamber B contains a piston 4 which moves along the longitudinal axis C of the cylinder and separates the cylinder chamber B into two subchambers Da, Db, which are each adjacent to one, but not the same, of the two cylinder ends 3a, 3b. The twosubchambers Da, Db each have a respective volume that depends on a position of the piston 4 along the longitudinal axis C of the cylinder C.

Here, the piston 4 is placed freely in the cylinder 2, achieving a tight fit with the cylinder 2 in order to provide an essentially fluid-tight barrier in the cylinder chamber B. At the same time, the compressor 1 should preferably be set up to ensure that relatively low frictional resistance occurs between the cylinder 2 and the piston 4 when the piston 4 moves along the longitudinal axis C of the cylinder. Under the influence of gravity Fg, piston 4 will thus tend to move towards the lowest point in the cylinder 2. That lowest point will usually be one of the cylinder ends 3a, 3b, depending on the rotational position of the cylinder 2. Only when cylinder 2 (particularly the longitudinal axis C of the cylinder) is fully horizontal, will the force of gravity Fg acting on the piston 4 not be directed at least in part towards one of the cylinder ends 3a, 3b. However,when this occurs, the piston 4 can still move towards one of the two cylinder ends 3a, 3b, e.g. due to mass inertia when the cylinder is continuously rotated.

Preferably each of the cylinder ends 3a, 3b should be provided with a separate inlet 5a, Sb for fluid to enter the cylinder chamber B and a separate outlet 6a, 6b to allow fluid to exit the cylinder chamber B and be directed to an external tank 7

(particularly one that surrounds the cylinder 2), with the inlet 5a, Sb and the outlet 6a, 6b each featuring a separate non-return valve 8. Each non-return valve 8 is designed to prevent the backflow of fluid. Apart from said inlets 5a, 5b and outlets 6a, 6b with non- return valves 8, the cylinder ends 3a, 3b should preferably provide a fluid-tight seal with regard to the cylinder chamber B.

A non-return valve, also known as a one-way valve, is a valve designed to allow a fluid flow in one direction and to block fluid flow in the opposite direction. A non-return valve is generally a passive valve that opens or closes depending on the direction of the pressure difference between the two valve sides. In the example shown, a non-return valve 8 can be opened and/or closed under the influence of gravity, as explainedelsewhere in this description with reference to Fig.2. As an addition or alternative, a non-return valve 8 can also be actively controlled, e.g. magnetically, depending on one or more sensors such as pressure sensors or depending on a timer.

In the example shown, each non-return valve 8 is located directly at its

respective inlet 5a, Sb or outlet 6a, 6b. It will be clear that, as an alternative or addition,a non-return valve can be positioned at a greater distance of the respective inlet or outlet, provided it be in the fluid flow path from or to that inlet or outlet. However, by positioning the non-return valves 8 directly at the respective inlets 5a, 5b or outlets 6a, 6b, dead volume can be reduced, improving the efficiency of the compressor 1.

The cylinder 2 can be rotated about a rotation axis K for the purpose of the displacement of the piston 4 by gravity Fg, in particular to direct a fluid situated in the cylinder chamber B into a tank 7 through outlet 6a, 6b, under the influence of the weight of the piston 4, with the rotation axis K enclosing an angle with the longitudinal axis C of the cylinder.

In Fig.1 the rotation axis K is perpendicular to the plane of the drawing, so that the rotation axis K encloses a right angle with the longitudinal axis C of the cylinder. In Fig.1, arrow Fg indicates the downward direction of gravity to which the compressor 1,including the piston 4, is subjected. It will be clear that the compressor 1 and in particular the cylinder 2 should preferably be supported during use, so that gravity can displace the piston 4 relative to the cylinder 2.

The cylinder 2 can be rotated about the rotation axis K in either or both of the directions of rotation R1, R2, either unidirectionally or alternating between bothdirections.

Optionally, the compressor 1 can comprise a rotary mechanism, indicated generally with 9, that has been designed to rotate the cylinder 2 about the rotation axis K. The rotary mechanism 9 can comprise, for example, a shaft suspension system (not shown), from which the cylinder 2 and possibly the tank 7 are suspended. The rotarymechanism 9 can be designed to allow for continuous rotation, e.g. rotation up to and beyond 360 degrees) in one or more directions R1, R2. Alternatively, the rotary mechanism 9 can be designed to allow the cylinder 2 to alternate between both directions R1, R2, rotating approximately 180 degrees each time. This allows for a particularly simple compressor 1 that does not require swivel joints.

Fig.1 shows a situation in which cylinder 2 is moving about the rotation axis from one cylinder end 3a to the other cylinder end 3b under the influence of gravity Fg. This displacement creates a pressure drop in subchamber Da, causing air to be sucked in through inlet 5a along the corresponding inlet valve 8, which is opened due to the pressure difference. At the same time, the corresponding non-return valve 8 at outlet 6aprevents air from being sucked out of the tank 7. Simultaneously, the displacement of the cylinder causes an increase in pressure in the subchamber Db, forcing air from that subchamber Db out through the outlet 6b, past the opened non-return valve 8. In this process, the non-return valve 8 at inlet 5b prevents the air from leaving subchamber Db through the inlet 5b.

As shown, the angle enclosed by the rotation axis K and the longitudinal axis C of the cylinder is between 30 and 150 degrees, preferably between 45 and 135 degrees, more preferably between 70 and 110 degrees and yet more preferably between 80 and 100 degrees, being approximately 90 degrees in this particular situation.

The compressor 1, e.g. featuring a support device (not shown), should preferably be designed to ensure that the rotation axis K remains on an essentially horizontal plane during use (see Fig.1).

The mass of the piston 4 should preferably be adjustable, with at least two different values.

Optionally, part of the cylinder 2, such as one of the cylinder ends 3a, 3b, or part thereof, could be temporarily removed from cylinder 2 to provide access to the cylinder chamber B so that the piston mass can be adjusted.

In the example shown, the compressor 1 comprises the tank 7, i.e. the tank 7 is an integral part of the compressor 1, with the tank 7 being connected with at least one and preferably each of the outlets 6a, 6b of the cylinder ends 3a, 3b. Alternatively, the compressor can be provided without a tank, with the outlet or outlets of the compressor featuring couplings that can be used to connect an external tank. A combination of aninternal tank 7 and an external tank is also possible.

The tank 7 should preferably be provided with a tank outlet (not shown) to discharge fluid from the tank 7 so that the accumulated fluid pressure and/or the associated fluid flow can be used.

The tank 7 may be a rollable or rotatable tank, with an essentially

circular/cylindrical wall enclosing an air reservoir and the tank 7 containing the piston/cylinder assembly 2,4 (see drawing). In particular, the tank wall may feature one or more bores to allow for the supply of air to one or more of the cylinder inlets 5a, 5b and/or these inlets may extend to the tank wall.

In the example shown, the compressor 1 is designed to have the tank 7 rotate along with the cylinder 2, with the tank 7 connected to the cylinder 2 by means of a fixed, non-invidually-rotating connection. Here, the cylinder 2 is enclosed by the tank 7, which has a rounded exterior. The tank 7 may comprise several storage tanks which may or may not be connected to each other. When the tank 7 is designed to rotate along with cylinder 2, the tank outlet (not shown) should preferably be fitted with a swivel joint (not shown) to attach one or more devices that can use the compressed air.

One or more of the outlets 6a, 6b may be provided with a hose (not shown) and/or a swivel joint (not shown) to provide a flexible fluid connection between the outlet 6a, 6b and the tank 7, in this case in particular an external tank which, for example, does not rotate along with the cylinder.

The compressor 1 should preferably be equipped with a drive mechanism (not explicitly shown) to actuate the rotation of the cylinder 2. The drive mechanism maycomprise a motor, e.g. an electric motor. Alternatively or additionally, the drive mechanism may be operated manually, featuring a crank and/or handle for said purpose.

Optionally, the cylinder 2 and/or the piston 4 may be equipped with a magnetic actuator (not shown) designed to displace piston 4 along the longitudinal axis C of thecylinder 2 under the influence of a magnetic force, for example before, during and/or after rotation.

The drawings also show an example of a method for compressing a fluid, with the piston/cylinder assembly being set in motion, e.g. being rotated, in such a way that the piston 4, under the influence of its weight, compresses fluid in the cylinder 2 anddirects it to a tank 7.

The method in this example can include providing a compressor 1, as described here, and rotating the cylinder 2 about the rotation axis K, with the compressor 1 being subjected to gravity Fg during rotation, while at least cylinder 2 is supported, whereby the piston 4 is displaced along the longitudinal axis C of the cylinder 2.

The compressor may be rotated manually and/or mechanically, e.g. by means of a motor. The compressor 1 may be driven through propulsion, e.g. rolling propulsion. Various methods may be used, e.g. a connecting rod, a drive belt and/or a chain.

Fig.2A-L show the compressor 1 of Fig.1 in different positions, with the compressor 1, in particular the cylinder 2, being rotated about the rotation axis K in -degree increments in the successive Figures 2B-L. Fig.2A-L thus show about one rotation cycle of the compressor 1.

In each of the Figures 2A-L, the rotation axis K is perpendicular to the plane of the drawing, as in Fig.1, while gravity Fg, as in Fig 1, is represented as a downward force. Fig.2A-L show how the compressor 1 shown in Fig.1 operates when the methoddescribed here is followed. It can be seen that, in the course of the rotation cycle, the piston 4 moves reciprocally between the cylinder ends 3a, 3b, causing air to alternately be sucked into each subchamber Da, Db through the corresponding inlet Sa, 6b and that air is subsequently directed to the tank 7 through the corresponding outlet 6a, 6b.

It can also be seen that gravity can only support and/or reinforce the operatien of the non-return valves 8, with the valves 8 always being inclined to look for essentially the lowest position valve position and thus to alternately open and close in accordance with the general operating principles of said valves, as described above.

Optionally, the method can include adjustments to the piston mass of the piston4, especially prior to rotating the cylinder.

Optionally, the method can include the magnetic actuation of the piston 4 in relation to the cylinder 2, e.g. before, during and/or after rotation. This current statement relates to the following aspect with the followingfollowing numbered embodiments. Fig.3 and Fig.4 relate to this aspect.

Compressor, which harnesses rotary motion and gravity, to compress and store air (or some other gas) so that this compressed air can be used for various purposes.

Examples include inflating (vehicle) tyres, supplying air (pressure) to pneumatic tools, ventilation or cooling systems, connecting an airbrush or paint sprayer, or othermachines/systems for which any form of air pressure is required.

For this purpose, the Compressor can be equipped, for example, with a rotatable hollow cylinder (Fig.3A) containing a free, tight-fitting piston (Fig.3B), which by virtue of its weight and gravity, has the property of moving towards the lowest position in the cylinder. (Fig.3L)

By rotating the cylinder of the compressor (perpendicular to its longitudinal axis), (Fig.3J or Fig.3K), the weighted piston enclosed in the cylinder moves reciprocally, as gravity continuously pulls/pushes the piston downwards (Fig.3L).

Because the cylinder is preferably sealed at both ends (Fig.3G), the reciprocating piston enclosed in the cylinder will, during the rotation cycle of the cylinder, alternatelycreate low pressure (negative pressure) on one side and high pressure (positive pressure) on the other side.

Because both ends of the sealed cylinder preferably have an inlet valve (Fig.3E) and an outlet valve (Fig.3D), the positive pressure will be released on one side of the cylinder by means of the outlet valve (fig.3H), while the negative pressure at the other end will ensure that air is drawn in via the inlet valve (Fig.3I). The excess pressure that is alternately released at each end of the cylinder through the outlet valves isstored/collected in a tank (Fig.3F).

This may be a stand-alone tank, connected to the ends of the rotating cylinder by means of swivel joints and air pressure hoses, as well as a tank mounted on the cylinder or a tank enclosing the cylinder, rotating along with the cylinder. In this case, the excess pressure that is alternately released from one of the two ends of the cylinder throughthe outlet valves, is stored directly in the tank. Via a swivel joint mounted on this rotating tank, the air pressure stored in the tank can be used for various purposes, as described above.

In the case of a stand-alone tank, it is not necessary for the cylinder (containing the piston) to rotate 360 degrees, and a back-and-forth rotation of approximately 180degrees will suffice, in order to eliminate the need for swivel joints. Instead, the flexible air hoses connecting the ends of the cylinder to the tank will take over their function.

The cylinder, or the cylinder mounted to or enclosed in the tank may be rotated manually, e.g. by means of a crank or by propelling the compressor with or without a handle, or by means of an electric motor, or any other device. This can be done bymeans of a direct, drive, connecting rod, drive belt, chain, or any such method.

The compressor can also be equipped with several cylinders and/or multiple tanks.

The cylinder, or the cylinder and tank assembly, can be rotated in 2 directions (Fig.3J and Fig.3K).

This embodiment of the Compressor is a machine that makes relatively little noise compared to conventional compressors, that requires fewer strokes and has relatively few (moving) parts.

Explanation Figure 3: (Cross-section of the Compressor with the cylinder enclosed in a tank) A Cylinder

B Weighted piston

C Tank wall

D Outlet valve

E Inlet valve

F Tank

G Sealed cylinder end (at both ends of the cylinder)

H High pressure air is discharged from the cylinder via outlet (to tank)

L Air is sucked into the cylinder through the inlet channel (along the inlet valve)

J Direction of rotation option 1

K Direction of rotation option 2

L The direction of the piston (in this Figure) under the influence of gravity (weight of piston)

Explanation Figure 4: The rotation cycle of the compressor (enclosed in the tank) shown in steps. Here, it can be seen how the piston and valves respond to the rotation cycle of the compressor.

Embodiment 1. The hollow cylinder with sealed ends, featuring inlet and outlet valves, containing a weighted piston, is rotated for a period of time, or continuously,with the weight of the piston, during much of the rotation, causing the piston to move downwards and the air in the cylinder under the piston being forced out of the cylinder through an opening one-way valve and into the tank of the Compressor.

Embodiment 2. The hollow cylinder with sealed ends, featuring inlet and outlet valves, containing a weighted piston, is rotated for a period of time, or continuously,with the weight of the piston, during much of the rotation, causing the piston to move downwards, resulting in the creation of negative pressure in the part of the cylinder above the piston. This causes the inlet valve (one-way valve) to open and "fresh" outside air to flow into the cylinder of the Compressor through the inlet channel.

Embodiment 3. The hollow cylinder with sealed ends, featuring inlet and outletvalves, containing a weighted piston, is rotated for a period of time, or continuously, with the continued buildup of pressure inside the tank gradually limiting the range of movement of the piston inside the cylinder. If the back pressure in the tank increases, the range of movement of the reciprocating piston inside the cylinder will decrease. If the back pressure in the tank, depending on the weight of the piston, has reached itsmaximum limit, the piston will no longer reciprocate, or will do so to a negligible extent, during rotation, thus generating no additional excess pressure. Although the invention is explained here with reference to embodiments and drawings, these do not constitute a limitation of the invention, which is defined by theconclusions. Many versions, combinations and extensions are possible, as skilled readers will be aware. A compressor designed according to the invention specified here can comprise any positive number of cylinders and pistons. Such a compressor can compress air, any other gas, or any other fluid. Further examples are given in the description.

In an adapted version of the compressor, the drop speed of the piston can be utilised.

Gravity velocity can be accelerated with electromagnets in order to generate more pressure. The piston initially compresses air, some of which is directed to the tank. The residual air at the bottom of the cylinder causes the piston to bounce back (air cushion), which is energy-efficient, reduces wear on the piston and produces less noise.

Tanks can also serve as a balance or counterweight to the piston.

The piston itself may feature valves, which could be opened by means of magnets, springs, compressed air, etc. on the upstroke and closed on the downstroke to generate pressure.

In an adapted version of the compressor, the piston can open and close valves by means of pressure, weight, magnets.

The piston can be made heavier to generate more pressure.

The circumference (cm) of the piston can be reduced.

The cylinder capacity can be reduced by inserting a second cylinder into the first cylinder. In this case, a smaller piston at the bottom of the main piston will fall into a second, smaller cylinder, generating more pressure. In addition to compressing fluids,the compressor can also be used to create a vacuum.