WO2009044260A1

WO2009044260A1 - Device for reciprocating machines and related reciprocating machine

Info

Publication number: WO2009044260A1
Application number: PCT/IB2008/002592
Authority: WO
Inventors: Gianluigi Benetti
Original assignee: Gianluigi Benetti
Priority date: 2007-10-02
Filing date: 2008-09-30
Publication date: 2009-04-09
Also published as: ITVI20070264A1

Abstract

The invention concerns a device (1, 100, 200) for reciprocating machines suited to convert a rotary motion into an alternate motion and/or vice versa, comprising a moving element (3, 3a, 3b) suited to be set in motion along a rectilinear axis (502) by kinematic means (5) suited to convert the rotary motion of a rotary shaft into an alternate motion and/or vice versa. Between the moving element (3a, 3b) and the kinematic means (5) there are means (6) suited to compensate for the movements transmitted by the kinematic means (5) along an axis that is not parallel to the rectilinear axis (502). The invention also concerns a reciprocating machine related to said device for reciprocating machines.

Description

DEVICE FOR RECIPROCATING MACHINES AND RELATED RECIPROCATING MACHINE.

The invention concerns the sector of reciprocating machines. In particular, the present invention concerns a device for reciprocating machines in general.

More specifically, the present invention concerns a device suited to convert the rotary motion of a shaft into a continuous rectilinear alternate motion or vice versa, to be used in reciprocating machines like, for example, compressors, pumps, engines, jet engines, hydraulic, pneumatic, and mixed motors. The invention concerns also the related reciprocating machine and, in particular, it concerns a reciprocating pump and a reciprocating compressor with membrane. As is known, in some types of reciprocating machines the conversion of the rotary motion of a shaft into the alternate motion of a moving member along its axis, like for example a plunger or piston inside a cylinder or an elastic membrane, is obtained by means of a device of the connecting rod-crank type. More particularly, in the sector of reciprocating membrane pumps, the above mentioned device is used for operating an elastic membrane that is kept locked at the level of its peripheral edge and free to oscillate in its central part in order to carry out the compression and intake stages. Said device of the connecting rod-crank type poses some drawbacks.

More particularly, a first drawback lies in that the connecting rod-crank device comprises moving mechanical parts that are coupled by means of joints and/or articulations with sliding surfaces. This leads to wear and reduces the operating life of said mechanical parts and therefore of the device, as well as of the corresponding reciprocating machine. Constant lubrication and frequent replacements are therefore necessary.

A further drawback connected with the previous one is constituted by the fact that, in the reciprocating machines using the device mentioned above, the vapours of the lubricant as well as any leakages and dispersions of the same contaminate the air, gas or liquid present in the machine itself. This makes it impossible to use these machines in the pharmaceutical, medical, chemical, nuclear sectors and in potentially explosive environments. A further drawback lies in that the translation-rotary motion of the connecting rod transmits to the moving member also force and motion components in undesired directions and in particular in transversal directions in relation to the axis of the desired alternate motion. These transversal stresses and thrusts cause power losses and also friction phenomena, and therefore wear in mechanical parts and structures of the device and/or of the related reciprocating machine, for example between cylinder and piston. Another drawback is constituted by the fact that the complexity of the device inevitably makes it heavy and cumbersome.

Another drawback is constituted by the fact that the large number of mechanical components makes the assembly operations rather complicated and maintenance difficult to carry out. These negative aspects become even worse in the case - for example that of compressors - where two opposing members of the connecting rod-crank type are used, each one suited to alternately move a corresponding piston, carrying out a compression and an intake cycle on each rotation of the shaft. Other solutions include the use of an elastic membrane that replaces the piston. A further drawback posed by these compressors is represented by the limited number of revolutions that they can perform per minute. In fact, beyond that limit the membrane breaks because of the undesired mechanical stresses to which it is subjected also along the axis that lies transversal to the axis of the alternate motion. This considerably reduces the efficiency of said compressors. The object of the present invention is to overcome all the drawbacks described above.

It is in particular one of the objects of the present invention to provide a device suited to convert the rotary motion of a shaft into a rectilinear alternate motion or vice versa, to be used in reciprocating machines like for example compressors, pumps, engines, jet engines, hydraulic, pneumatic, and mixed motors, as well as a related alternating machine and, more specifically, a reciprocating pump and a reciprocating compressor with membrane.

It is another object of the invention to produce a device that has fewer mechanical components than comparable devices of known type. It is a further object of the invention to produce a device in which the mechanical components have simpler couplings, substantially without sliding surfaces, than comparable devices of known type.

It is a further object of the invention to provide a device in which friction between the reciprocally moving parts is reduced to a minimum. It is another object of the invention to provide a device that is per se more reliable than comparable devices of known type, and whose moving parts are subjected to negligible wear and are therefore more durable.

It is another object of the invention to provide a device and a reciprocating machine that during operation are subjected to low energy loss in the form of heat.

It is another object of the invention to provide a device that requires less maintenance than comparable devices of known type.

It is a further object of the invention to provide a device that does not need lubrication. It is another object of the invention to provide a device that does not transmit passive stresses and thrusts in directions that are transversal to the direction of the alternate motion it obtains.

It is another object of the invention to provide a device that makes it possible to move a moving member with alternate motion along its own axis and to which it can be rigidly connected with no need to use joints and articulations.

It is another object of the invention to provide a device that is lighter and smaller than comparable devices of known type.

It is a further object of the invention to provide a device in which the mechanical components can be easily removed and replaced for maintenance purposes. It is another object of the invention to provide a device and a machine that are more efficient than comparable devices and machines of known type.

It is another, yet not the least object of the invention to provide a device and a machine that are economic and simple, as well as easy to construct and to assemble. The objects described above are achieved by a device for reciprocating machines and a related reciprocating machine as described and characterized in the respective independent claims.

Advantageous embodiments of the invention are described in the dependent claims. Advantageously, the proposed solution makes it possible to produce a device suited to be used also in reciprocating machines that must not present the risk of contaminating the air, gas or liquid present therein.

Still advantageously, the solution proposed makes it possible to produce a device and a reciprocating machine suited to be used in specific sectors like, for example, the pharmaceutical, chemical, medical, nuclear sector, and in potentially explosive environments.

Still advantageously, the proposed solution makes it possible to carry out a device where friction is substantially absent, and therefore to considerably reduce wear and power losses at the level of the moving parts. Still advantageously, the proposed solution makes it possible to carry out a device where the components of motion that are transversal to the axis of the desired alternate motion are substantially equal to zero.

Still advantageously, the proposed solution makes it possible to carry out a device that can be used also in double-acting reciprocating machines, Still advantageously, the proposed solution makes it possible to produce a device that is lighter and smaller than comparable solutions of known type. Still advantageously, the proposed solution makes it possible to carry out a device that can operate in horizontal and/or vertical and/or inclined position. Still advantageously, the proposed solution makes it possible to produce a reciprocating pump and a reciprocating machine with membrane capable of carrying out a higher number of compression and intake cycles than the reciprocating membrane pumps and compressors of known type. The objects and advantages illustrated above will be highlighted in greater detail in the description of some preferred embodiments of the invention, provided as non-limiting examples with reference to the attached drawings, wherein:

Figure 1 shows a schematic view of a longitudinal section of an example of embodiment of a reciprocating machine according to the invention and of a device suited to convert a rotary motion into an alternate motion which is also the subject of the present invention, in a first operating position; - Figure 2 shows a schematic sectional view of the reciprocating machine and of the device shown in Figure 1 in the same operating position;

Figure 3 shows a schematic view of a longitudinal section of the device shown in Figure 1 in the same operating position;

Figure 4 shows a schematic sectional view of the device shown in Figure 1 in the same operating position;

Figure 5 shows a schematic view of a longitudinal section of the reciprocating machine and of the device shown in Figure 1 in a different operating position;

Figure 6 shows a schematic sectional view of the reciprocating machine and of the device shown in Figure 1 in the same operating position illustrated in Figure 5;

Figure 7 shows a schematic view of a longitudinal section of the reciprocating machine and of the device shown in Figure 1 in a further operating position; - Figure 8 shows a schematic sectional view of the reciprocating machine and of the device shown in Figure 1 in the same operating position illustrated in Figure 7;

Figure 9 shows a schematic view of a longitudinal section of the reciprocating machine and of the device shown in Figure 1 in a further operating position;

Figure 10 shows a schematic sectional view of the reciprocating machine and of the device shown in Figure 1 in the same operating position illustrated in Figure 9;

Figure 11 shows a schematic sectional view of a construction variant of the device that is the subject of the invention;

Figure 11a shows a schematic sectional view of a construction variant of the device that is the subject of the invention;

Figure 12 shows a schematic view of a longitudinal section of a construction variant of the device that is the subject of the invention; - Figure 13 shows a schematic sectional view of the device shown in Figure 12;

Figure 14 shows a schematic view of a longitudinal section of a further example of some parts of a construction variant of a reciprocating machine carried out according to the invention; - Figure 15 shows a schematic view of a first cross section of the machine shown in Figure 14 along plane A-A;

Figure 16 shows a schematic view of a first cross section of the machine shown in Figure 14 along plane B-B;

Figure 17 shows a schematic sectional view of a further example of some parts of a construction variant of a machine carried out according to the invention.

By way of introduction, it is important to point out that corresponding components in different examples of embodiment are indicated by the same reference numbers. In the case of a change in the position of the parts that make up the invention, the position indications given in the individual executive examples must be transferred, according to logic, to the new position.

While the following description, made with reference to the above mentioned figures, illustrates some particular embodiments of the present invention, it is clear that the invention is not limited to said particular embodiments, rather, the individual embodiments described here below clarify different aspects of the present invention, the scope and purpose of which are defined in the claims. More specifically, the examples of embodiment of the invention described here below refer to a device suited to convert the rotary motion of a shaft into a rectilinear alternate motion to be used in reciprocating machines and they also refer to a related reciprocating machine.

It is clear that the proposed solution can be applied to any reciprocating machine or apparatus in which it is necessary to convert a uniform rotary motion into a rectilinear alternate motion or vice versa, like for example a pump, engine, jet engine, hydraulic, pneumatic or mixed motor.

More specifically, Figures 1 and 2 show some parts of a reciprocating machine indicated as a whole by 500, provided with a device 1 suited to convert a rotary motion into an alternate motion and forming the subject of the present invention. More precisely, in the non-limiting example illustrated herein, the reciprocating machine 500, which also forms the subject of the present invention, is constituted by a membrane compressor.

The membrane compressor 500 comprises two opposing and coaxial membranes 501 that are fixed at the level of their peripheral edge, each one of them being free to oscillate along an axis 502 inside a corresponding chamber 503 in order to carry out the compression and intake stages. Each chamber 503 is also provided with first valve means 504 and second valve means 505 suited to regulate, in coordination with the movement of the membrane 501, the flow of air into the chamber 503 during intake from a suction duct 506 and its outflow from the chamber 503, during the compression stage, towards a delivery duct 507. A device 1 suited to convert a rotary motion into an alternate motion moves the two membranes 501 inside the chambers 503 in order to carry out, in coordination with the opening/closing of the above mentioned valve means 504 and 505, the above mentioned air compression and intake stages. More specifically, the device 1, shown in detail in Figures 3 and 4, comprises at least one moving element 3 suited to be set in motion along a rectilinear axis 502 by kinematic means 5 suited to convert the rotary motion of a rotary shaft not represented herein into an alternate motion.

According to the invention, between the moving element 3 and the kinematic means 5 there are means 6 suited to compensate for the movements along axes that are not parallel to the rectilinear axis 502.

More particularly, the means 6 are suited to compensate for the movements along an axis that is transversal and/or orthogonal to said rectilinear axis 502, transmitted by said kinematic means 5.

Said means 6 reduce wear and energy losses due to friction, owing to the fact that they advantageously make it possible to compensate for the undesired movements transmitted by the kinematic means 5 to each membrane 501.

In the non-limiting example of embodiment of the invention illustrated herein, the means 6 comprise elements 8 suited to roll in the relative seats.

More specifically, in the particular embodiment illustrated herein, the elements 8 are constituted by one or more balls and more precisely by a plurality of balls arranged in one or more parallel lines, as shown in Figure 4, free to roll in corresponding rectilinear and parallel seats obtained for this purpose in the mutually facing surfaces 10, 11 respectively belonging to the kinematic means 5 and to each moving element 3. The means 6 also comprise a cage 12, visible in Figure 3, suited to space the rolling elements 8 from one another.

This advantageously allows for a mutual translation movement with minimum friction in a direction orthogonal to the axis 502 of the membrane 501 between the kinematic means 5 and each moving element 3. Still advantageously, this allows the kinematic means 5 to transmit to each membrane 501 only one force component parallel to the axis 502, without transmission of stresses and thrusts in any directions different from the latter.

It is clear that, alternatively, the rolling elements 8 can consist of straight rollers or needles or other equivalent elements. As regards the kinematic means 5, they comprise an eccentric joint 13 having a first end 13a suited to be fixed to a rotary shaft that is not visible herein and a second end 13b rotatingly coupled with a central parallelepiped body 14.

More specifically, in the non-limiting example illustrated herein, the second end

13b is rotatingly coupled with the central body 1 via a rolling bearing 20 housed inside an axial through opening in the central body 14. The end 13b is connected to the central body 14 by means of a screw 15 coupled with a threaded hole 16 obtained in the end 13b itself.

This advantageously makes it possible to reduce to a minimum any friction between the eccentric joint 13 and the central body 3, as well as any wear and power losses.

The threaded hole 16 is misaligned in relation to a hole 17 present in the first end 13a of the joint 13. The hole 17 is suited to house a terminal portion of said rotary shaft preferably belonging to an electric motor. More specifically, the distance between the two axes 19 and 18 of the above mentioned holes 16 and 17 determines the eccentricity of the joint 13.

The central body 14 is thus mounted eccentrically in relation to the rotary shaft and is moved by the latter so that its centre describes a circumference whose centre is on the axis 18 and whose radius is equal to the distance between the two axes. As far as the moving elements 3 are concerned, in the preferred embodiment of the invention illustrated herein they comprise two plates 3a and 3b connected to each other in such a way as to define a housing inside which there are the means 6 and the central body 14 of the kinematic means 5. More specifically, the two plates 3 a and 3b are connected to each other via connection means indicated as a whole by 23.

In the preferred embodiment of the invention illustrated herein, said connection means 23 comprise at least two rods 24 whose ends are connected to the plates 3a e 3b via fixing means 25, as shown in the enlarged detail of Figure 4. More specifically, the fixing means preferably comprise anchorage screws 26 suited to be inserted in corresponding threaded axial holes made in the ends of the rods or columns 24.

It should also be observed that, always according to a preferred embodiment of the invention, the device 1 also comprises means, indicated as a whole by 28 in Figure 4, suited to compensate for any clearances or slacks that may be present between the central body 4 and each moving element 3 due for example to the wear of the means 6.

This advantageously makes it possible to prevent said clearances or slacks from causing undesired vibrations and stresses during the operation of the device 1, as well as untimely wear and breakage of the means 6 and of other parts of the device 1. More specifically, in the preferred non-limiting embodiment of the invention illustrated herein, said means 28 comprise elastic means and, more precisely, two Belleville washers 29 that maintain the rolling bodies 8 constantly in contact with the surfaces 10, 11 of the central body 14 and of the moving elements 3. More precisely, each Belleville washer 29 is interposed between the head of the anchorage screws 26 and each rod or column 24, as shown also in the enlarged detail of Figure 4.

It should also be observed that the operator, by properly adjusting the tightening of the screws 26, controls also the force exerted on the rolling elements, in such a way as to allow the elements 8 to roll in the relative seats without any clearance and slack and with minimum friction.

Thus, the proposed solution advantageously makes it possible to substantially eliminate the energy losses, for example due to friction, that characterize the comparable traditional systems. A first construction variant of the device subject of the invention, indicated as a whole by 100 in Figure 11, is differentiated from the previous one due to the fact that the moving elements 3 and the elastic means 28 are constituted by a single element 40 comprising an elastic body. More particularly, said elastic body comprises two U-shaped parts 40a and 40b and has two opposing parts that define the housing in which the kinematic means and the means 6 are arranged. This advantageously makes it possible to further reduce the number of components of the device 100, thus simplifying its assembly procedure. Another construction variant of the device subject of the invention, indicated as a whole by 100a in Figure l la, is differentiated from the previous one due to the fact that the single element 40 it is an elastic body comprises an hollow body preferably including a tubular element 40c.

This advantageously makes it possible to further reduce the number of components of the device 100a, thus simplifying its assembly procedure. A further construction variant of the device that is the subject of the invention, indicated as a whole by 200 in Figures 12 and 13, is differentiated from the previous one owing to the fact that the means 6 comprise a shaped seat 50 within which the bearing 51 coupled with the kinematic means 5 is free to move. More specifically, the bearing 51 is free to roll inside the seat 50 that is shaped in such a way as to compensate for the transversal movements in relation to the axis 502 transmitted by the kinematic means to the bearing 51. The surface 52 of the bearing, in fact, can roll, without sliding, on the surface 53 ofthe seat 50.

Figures 14, 15 and 16 illustrate another example of embodiment of a reciprocating machine that is the subject of the present invention, indicated as a whole by 600.

More specifically, in this embodiment the machine is constituted by a membrane compressor comprising four membranes 501.

As can be observed, the proposed solution advantageously makes it possible to produce a membrane compressor having four membranes arranged in such a way as to be coplanar in pairs, thus reducing the overall dimensions of the compressor pump to a minimum and also reducing the number of components compared to the compressors of known type.

More specifically, the compressor comprises two devices indicated by 1, of the type previously described, positioned one after the other in a cascade arrangement, joined by second kinematic means or intermediate transmission means indicated by 80 in Figure 14.

More precisely, the two rectilinear movement axes 502a and 502b of the membranes of the two devices are offset of an angle preferably equal to 90°.

Figure 17 shows another example of embodiment of a reciprocating machine carried out according to the invention. More specifically, in this embodiment the machine 700 is constituted by an engine that uses the device 1 of the invention to convert the alternate motion of the moving elements 3 into the rotary motion of the output shaft.

More particularly, in the example illustrated herein, the engine comprises two combustion chambers 90 provided with mixture intake valves 91 and two combustion gas exhaust valves 92. The engine 700 is also provided with two spark plugs 93.

The operation of the device that is the subject of the invention is described with reference to the reciprocating machine represented in Figures 1 and 2, since a comparison with the other construction variants described does not show any substantial differences.

The rotation of the first end of the eccentric joint, for example obtained via the shaft of an electric motor, determines a consequent movement of the second end

13b of the joint both along the axis 502 and along one of its transversal axes. The translation along the transversal axis, as shown in the Figures from 5 to 10, is made possible by the means 6 that allow the central body 14 to move inside the housing along said transversal axis. This prevents this undesired translation movement from being transmitted to the two moving elements 3a and 3b and therefore to the two membranes 501. This considerably reduces their wear while at the same time enhancing the compressor performance.

On each complete rotation of the first end of the eccentric joint, the device performs a complete alternate movement and the compressor carries out a complete air intake and compression cycle in each chamber, as schematically shown in Figures 1, 2, and from 5 to 10. The above description clearly shows that the solution proposed allows the drawbacks described to be eliminated.

In particular, the solution proposed advantageously allows excessive deformations of the membrane to be avoided. Still advantageously, since no lubricants are required, the proposed solution eliminates pollution due to the dispersion of oil vapours.

Even though the invention has been described making reference to the attached drawings, upon implementation changes can be made that shall all be considered protected by the present patent, provided that they fall within the scope of the inventive concept expressed in the following claims. It is also important to remember that when the details mentioned in the claims below are followed by references, these must be understood as meant to improve the comprehensibility of the claim in question and not as a limit to the interpretation of the same. It should also be underlined that all the parts can be replaced with other technically equivalent parts, that any material can be used, provided that it is compatible with the intended use, and that the various elements can have any size, depending on the needs.

Claims

1) Device (1, 100, 100a, 200) for reciprocating machines, suited to convert a rotary motion into an alternate motion and/or vice versa, comprising at least one moving element (3, 3a, 3b) suited to be set in motion along a rectilinear axis (502) by kinematic means (5) suited to convert the rotary motion of a rotary shaft into an alternate motion and/or vice versa, characterized in that between said at least one moving element (3, 3a, 3b) and said kinematic means (5) there are means (6) suited to compensate for the movements transmitted by said kinematic means (5) along an axis that is not parallel to said rectilinear axis (502).

2) Device (1, 100, 200) according to claim 1), characterized in that said axis is transversal and/or orthogonal to said rectilinear axis (502).

3) Device (1, 100, 200) according to claim 1) or 2), characterized in that said means (6) comprise rolling elements (8) suited to roll in corresponding seats. 4) Device (1, 100, 200) according to claim 3), characterized in that said elements (8) are numerous and arranged in one or more lines.

5) Device (1, 100, 200) according to claim 3) or 4), characterized in that said seats are rectilinear.

6) Device (1, 100, 200) according to claim 5), characterized in that said seats are rectilinear and parallel to one another.

7) Device (1, 100, 200) according to claim 3) or 4) or 5) or 6) or 7), characterized in that said seats are obtained on mutually facing surfaces (10, 11) respectively belonging to the kinematic means (5) and to each moving element (3). 8) Device (1, 100, 200) according to any of the claims from 3) to 7), characterized in that said elements (8) comprise one or more balls. 9) Device (1, 100, 200) according to any of the claims from 3) to 7), characterized in that said elements (8) comprise straight rollers or needles or other equivalent elements. 10) Device (1, 100, 200) according to any of the preceding claims, characterized in that said means (6) also comprise a cage (12) suited to space said rolling elements (8) from one another. 11) Device (1, 100, 200) according to any of the preceding claims, characterized in that said kinematic means (5) comprise an eccentric joint (13). 12) Device (1, 100, 200) according to claim 11), characterized in that said eccentric joint has a first end (13a) suited to be fixed to a rotary shaft and a second end (13b) rotatably coupled with a central body (14).

13) Device (1, 100, 200) according to claim 12), characterized in that said second end (13b) is rotatably coupled with the central body (14) via a rolling bearing (20).

14) Device (1, 100, 200) according to any of the preceding claims, characterized in that it comprises two moving elements (3) provided with two plates (3a, 3b) connected to each other via connection means (23) in order to define a housing inside which the means (6) and the kinematic means (5) are arranged. 15) Device (1, 100, 200) according to claim 14), characterized in that said connection means (23) comprise at least two rods (24) connected to said plates (3a, 3b) via fixing means (25).

16) Device (1, 100, 200) according to claims 14) or 15), characterized in that it also comprises means (28) suited to compensate for any clearances or slacks present between said kinematic means (5) or said central body (14) and said two moving elements (3), said means (28) being suited to maintain said means (6) in contact with said central body (14) and said at least one moving element

(3).

17) Device (1, 100, 200) according to claim 16), characterized in that said means (28) comprise at least one elastic element.

18) Device (1) according to claim 17), characterized in that said elastic element comprises at least one belleville washer (29).

19) Device (100) according to claims 14), 16) and 17), characterized in that said two moving elements (3), said at least one elastic element (28) and said connection means are constituted by a single element (40).

20) Device (100) according to claim 19), characterized in that said element (40) comprises a substantially U-shaped elastic body or hollow body or a tubular element (40c).

21) Device (200) according to any of the preceding claims, characterized in that said means (6) comprise a shaped seat (50) within which a bearing (51) coupled with said kinematic means (5) is free to move.

22) Device (200) according to claim 21), characterized in that said seat (50) is shaped in such a way as to compensate for the transversal movements in relation to the axis (502) transmitted to said bearing (51) by the kinematic means (5). 23) Reciprocating machine (500, 600, 700) provided with one or more devices (1, 100, 200) suited to convert a rotary motion into an alternate motion and/or vice versa, characterized in that at least one of said one or more devices (1, 100, 200) is carried out according to any of the preceding claims. 24) Machine (700) according to claim 23), characterized in that it is an engine/motor.

25) Machine (500, 600) according to claim 23), characterized in that it is a membrane compressor.

26) Machine (500, 600) according to claim 25), characterized in that it comprises two membranes (501), each one of which is free to oscillate along an axis (502, 502a, 502b) inside a corresponding chamber (503), each provided with first valve means (504) and second valve means (505) suited to regulate the flow of air into said chamber (502, 503) during intake from a suction duct (506) and its outflow from said chamber (502, 503) towards a delivery duct (507) during the compression stage.

27) Machine (600) according to any of the claims from 23) to 26), characterized in that it comprises at least two devices (1, 100, 200) positioned one after the other in a cascade arrangement and joined by second kinematic or transmission means (80). 28) Machine (600) according to claim 27), characterized in that the two rectilinear axes (502a, 502b) of said at least two devices are offset of an angle preferably equal to 90°.