WO2006103362A2

WO2006103362A2 - Device for reversibly transforming a reciprocating rectilinear movement into a rotational movement, and related machines

Info

Publication number: WO2006103362A2
Application number: PCT/FR2006/000731
Authority: WO
Inventors: Maurice Bellier
Original assignee: Maurice Bellier
Priority date: 2005-04-01
Filing date: 2006-04-03
Publication date: 2006-10-05
Also published as: WO2006103362A3; EP1880121A2; FR2883948A1; FR2883948B1

Abstract

The invention concerns a device for transforming a rotational movement of a shaft (8) rotating about an axis of rotation (9), into a reciprocating rectilinear movement of a mobile part along a direction substantially parallel to said axis or inversely, comprising an oscillating plate (25) with axis (14) inclined relative to the axis (9) of the shaft (3), the intersection of said axes (9, 14) defining a instantaneous center of rotation O of the oscillating tray. The device is further provided with at least one spindle-forming shaft (27) extending substantially perpendicular relative to said axis (14), an axis of said spindle passing substantially through the instantaneous center of rotation O of the oscillating plate, and a linking element extending substantially perpendicular relative to the axis of the spindle and relative to the axes (9, 19) of rotation of the shaft and of translation of the mobile part, said linking element co-operating with the spindle and being designed to be mounted on the mobile part.

Description

Reversible transformation device of a reciprocating rectilinear motion into a rotational movement, and associated machines.

The present invention relates to the field of devices for the reversible transformation of a rotational movement of a shaft rotating around its axis of rotation, in a reciprocating rectilinear motion of a part movable in a direction substantially parallel to said axis, in particular for pumps or internal combustion engines. In general, an internal combustion engine comprises an engine block in which cylinders are formed, and pistons able to move in translation inside the cylinders, each connected to a connecting rod, itself connected to a crankshaft. The connecting rod and crankshaft assembly makes it possible to transform the reciprocating translation movement of the pistons into a rotary movement. A crankshaft comprises crank pins in contact with the connecting rod heads, journals centered on the axis of rotation of the crankshaft and flanges connecting the crank pins to these pins. For a satisfactory engine operation, it is necessary to provide a particularly precise machining of the engine block to obtain the geometric tolerances required at the perpendicularity of the crankshaft axis with the planes in which the pistons move, but also at the level of the parallelism of the axes of the pistons, the crank pins, and the axis of rotation of the crankshaft.

Also known are pumps and hydraulic motors comprising a housing inside which is mounted a shaft rotating about an axis, an oscillating plate mounted on said shaft and provided with a contact surface with axial pistons regularly distributed on a circumference, animated by an alternating translational movement in a direction substantially parallel to the axis of rotation of the rotating shaft, during the rotation of said shaft. The contact between the swashplate and the pistons can be achieved by means of so-called "hydraulic" shoes articulated on spherical heads of the pistons, and the contact between said pistons and the swash plate is then maintained by means of a plywood resting on a shoulder of the hydraulic pads.

It is also possible to make the contact between the swashplate and the pistons by a rounded shape of the heads of the pistons, maintaining the contact being provided by return springs.

Such devices make it possible to return the pistons when the inertial forces are low because of the low mass of the pistons in reciprocating rectilinear motion and when the rotational speeds are moderate. However, these devices are unsuitable as soon as the mass of the pistons becomes large, for example of the order of one kilogram, and as soon as the rotational speed reaches several thousand revolutions per minute, the forces of inertia then becoming considerable.

The present invention therefore aims to remedy this drawback by proposing a device for reversibly transforming a rotational movement of a shaft rotating about an axis of rotation, in rectilinear reciprocating movement of a moving part in one direction. substantially parallel to said axis, for transmitting significant forces, including those generated by the reciprocating movement of the moving part.

The present invention also aims to provide a particularly simple, efficient, accurate, and economical processing device. For this purpose, the device for transforming a rotational movement of a shaft rotating about an axis of rotation into reciprocating rectilinear motion of a moving part in a direction substantially parallel to said axis or vice versa, comprises a crank pin of axis inclined with respect to The axis of the shaft, an oscillating plate mounted on the crankpin, the intersection of said axes defining the instantaneous center of rotation of the swashplate.

According to one aspect of the invention, the device is further provided with at least one trunnion shaft extending substantially perpendicularly with respect to said crankpin, an axis of said trunnion substantially passing through the instantaneous center of rotation of the swashplate. , and a connecting element extending substantially perpendicular to the axis of the journal and relative to the axes of rotation of the shaft and translation of the movable part, said connecting element cooperating with the journal and being intended to be mounted on the moving part.

Such a device has the advantage of including elements of simple design, including cylindrical axes and corresponding lesages, and dimensions easily adaptable to mechanical stresses depending on the desired application. In addition, the device comprises a small number of parts: the swash plate and the pins advantageously made integrally, the connecting element and the moving part. This makes it possible to obtain a coupling between the moving part and the swash plate in a particularly economical and reliable manner.

During operation of the device, the journal is animated with respect to the connecting element of a waving movement consisting of a rotation on its axis of an angle of ± α, α being the angle of inclination of the plate relative to the axis of rotation of the rotating shaft, this rotation being generated by the oscillating movement of the plate, and secondly a sliding inside the bore of the element linkage generated by the combination of the angular movement of the trunnion and the rectilinear motion to the lternative of the moving part. Such wobble movement combined with relatively low rotational and slidable pin speeds thus allow for relatively low wear and frictional dissipation, which enhances the reliability of the device.

Similarly, during operation of the device, the trunnion oscillates by an angle of ± α in the plane containing the axis of translation of the moving part and passing through the instantaneous center of rotation of the swash plate. This oscillation causes a rotation of an angle of ± α of the connecting piece relative to the moving part along an axis perpendicular to this plane. This low amplitude and low speed rotation makes it possible to obtain relatively low friction wear and energy. In addition, the wobbling movement of the trunnion, as well as the centering of the forces at the connecting element and the possibility of guiding the moving part to the right of the connecting element makes it possible to obtain a particularly secure device and effective. Furthermore, the arrangement of a trunnion extending perpendicularly to the axis of rotation of the swashplate and passing through its instantaneous center of rotation makes it possible to fix in rotation the oscillating plate by materializing, for example, this trunnion under the shape of a cylindrical finger guided by a guide rail. The direction of this slide, which is preferably parallel to the direction of movement of the moving part, gives the direction of the plane of oscillation of the trunnions.

Preferably, the connecting element comprises a bore inside which is mounted the journal allowing displacements of said journal relative to the connecting element, the axis of said bore being perpendicular to an axis of rotation of the element. link.

Preferably, the connecting element is movable in translation relative to the moving part along an axis substantially perpendicular to the axes of rotation of the shaft and translation of the moving part.

This design makes it possible to remedy any manufacturing defects, in particular defects in parallelism between the axis of rotation of the rotating shaft and the axis of translation of the moving part, the axis of translation of the moving part and of the axis of the guide rail and thus avoid the provision of relatively tight manufacturing tolerances between said axes.

Advantageously, the connecting element is movable in rotation relative to the moving part along an axis substantially perpendicular to the axes of rotation of the shaft and of translation of the moving part, which makes it possible to remedy any defects. manufacturing, the axis of the movable part may, while remaining in the same plane as the axis of the rotating shaft, have a slight angle of inclination relative to the position corresponding to a perfect parallelism of these two axes , without that the operation is altered. We can even design the device with a slight inclination to allow a better transmission of forces. In one embodiment, the trunnion comprises abutments so as to allow locking in translation of the connecting element with respect to the trunnion, the device comprising, in addition, a connecting rod hinged to the connecting element and intended to be articulated on the moving part. In one embodiment, the connecting element is provided with a cylindrical body comprising a bore inside which the trunnion is mounted, the axis of said bore being perpendicular to an axis of the cylindrical body. The axis of said bore is advantageously located in a median plane of the cylindrical body and concurrent with the axis thereof.

In another embodiment, the connecting element is provided with a parallelepiped shaped body comprising, in a median plane of said body, a bore inside which said trunnion is mounted, and two radially extending axes. relative to the bore, along a common axis and perpendicular to two parallelepipedal faces parallel to said median plane. Advantageously, the axis of the bore coincides with the main axis of the parallelepiped, the common axis of the axes and the axis of said bore being perpendicular and concurrent.

In another embodiment, the connecting element is provided with a parallelepiped body comprising two opposite outer faces forming cylindrical portions of the same center, and a bore inside which said trunnion is mounted, the axis of said bore. being perpendicular to a main axis of the parallelepiped body.

The connecting element may also be provided with a spherical body comprising a bore, preferably centered on the axis of the sphere, inside which said trunnion is mounted. Said bore is advantageously located in a median plane of the spherical body.

The invention also relates to a piston engine, particularly a motor vehicle engine or a pump, comprising a motor unit, a shaft rotating about an axis of rotation, pistons sliding in cylinders formed in the engine block in one direction substantially parallel to said axis of rotation, and a device for transforming a rotational movement of the rotating shaft into reciprocating rectilinear motion, the piston or vice versa. The device is provided with a crank pin extending along an axis inclined relative to the axis of the shaft, and a swash plate mounted on said crankpin, the intersection of said axes defining an instantaneous center of rotation of the plate. oscillating. The device is further provided with at least one trunnion shaft extending substantially perpendicularly with respect to said arm, an axis of said trunnion substantially passing through the instantaneous center of rotation of the swash plate, and a connecting element extending substantially perpendicular to said journal and relative to the axes of rotation of the shaft and translation of the movable part, said connecting element cooperating with the journal and being intended to be mounted on the movable part. Advantageously, the machine is provided with two oscillating plates arranged symmetrically with respect to a median plane of the engine block and each comprising at least one trunnion, and pistons arranged in the same cylinder symmetrically with respect to said median plane. This arrangement has the advantage of obtaining a balancing of the moving elements, namely the oscillating plates, the journals and the pistons without it being necessary to provide balancing masses or to dynamically solicit the engine block, the eq. balancing the inertial forces and the forces applied to the pistons soliciting only the shaft supporting the oscillating trays.

Moreover, because of the design of the oscillating plates and the disposition of the trunnions, the polar inertia of this assembly is relatively limited, its mass being concentrated towards the center.

By combining this device with known techniques to vary the angle of inclination of the swash plate, the distance separating the swash plate and the engine block, a piston engine with variable displacement and variable compression ratio is obtained. .

In the form of an opposed piston engine, operating according to the light-distributed 2-stroke cycle, the variation of the distance between the oscillating trays, the inclination of one or both oscillating plates, the angular offsets of said trays. relative to the axis of rotation of the rotating shaft, it is possible to modify the cubic capacity, the compression ratio and, to a lesser extent, modify the tra nsert of the engine gases. It is also conceivable, for example, a motor or a pump comprising a single swash plate placed in the center of a set of pistons in the form of a cylinder having a single connecting piece in the median plane of this cylinder and a head at each end. axial and cylinders developing on either side of the swash plate, all can be completed by a balancing swash plate.

Also, a swash plate device according to the invention is such that said plate is mounted oscillating on a rotary shaft capable of rotational movement and connected to at least one moving part in a rectilinear motion, for the transformation of a said movements in the other, said device further comprising a connecting element forming an articulation with said swash plate and said moving part, said plate comprising a pin engaged with the connecting element, this element being housed in a recess adapted to the movable part, the movable part comprising a lateral opening for transversely introducing the connecting element and the pin, by the same opening. The recess is preferably delimited, in the moving direction of the moving parts, by the cylindrical portions and, between the cylindrical portions, by the openings. formed in opposed planed faces of the movable parts, the openings being separated from each other by two solid uprights. Preferably, the opposite planed faces are parallel to each other. Advantageously, the cylindrical surfaces of the movable part are carried by pads reported on said moving part.

Advantageously, a clearance is provided between the connecting element and the amounts. Thus, in the case where the device comprises at least two moving parts, it suffices that only one is such that the connecting element of said movable part is adjusted between the uprights of said moving part, the at least one another moving part being such that there is a clearance between the connecting element and the amounts of said other moving part.

The connecting element advantageously comprises cylindrical surfaces adapted to cooperate with the cylindrical surfaces of the recess, so that the element is rotatably mounted about an axis substantially perpendicular to the displacement of the moving part. Advantageously also, it is formed of a cylinder portion truncated by two flats substantially parallel to the axis of said cylinder. The flats may be substantially parallel to each other. Also, may not be parallel to each other, so that one of the cylindrical surfaces of the connecting element is narrower than the other. The connecting element may further comprise a bore pierced between the two flats, to introduce the trunnion. Advantageously, a minimum length of the openings, measured according to the direction of movement of the moving parts, is greater than or equal to a maximum distance between the flats.

The journal can form a sliding pivot connection with the connecting element. Also, the device may comprise a connecting rod in which the recess is formed, the journal then being locked in translation in the connecting element.

The invention also relates to a machine, especially a motor vehicle engine, a compressor or a pump, equipped with a device according to the invention, said movable part comprising a piston. This machine may be provided with two oscillating plates arranged symmetrically with respect to a median plane and each comprising at least one trunnion, and pistons arranged in the same cylinder symmetrically with respect to said median plane. In addition, it may comprise means for bringing the two oscillating plates together, which makes it possible to obtain a compression volume, and therefore a variable compression ratio. The present invention will be better understood on reading the detailed description of embodiments taken by way of nonlimiting example and illustrated by the accompanying drawings, in which: - Figure 1 is an axial sectional view of the pump provided with the reversible transformation device for rotational movement in reciprocating rectilinear motion according to a first embodiment of the invention, FIG. 2 is a cross-sectional view of the device of FIG. 1 along axis II-II, when the axis the journal is aligned with said axis II-II; FIG. 3 is an axial sectional view of the pump provided with the reversible motion transformation device according to a second embodiment of the invention; FIG. cross section of the device of Figure 3 along the axis IV-IV, when the axis of the pin is aligned with said axis IV-IV, Figure 5 is an axial sectional view of the pump provided with the transformer device According to a third embodiment of the invention, FIG. 6 is a cross-sectional view of the device of FIG. 5 along axis VI-VI, when the axis of the journal is aligned with said axis VI. FIG. 7 is an axial sectional view of a pump provided with a reversible motion transformation device according to a fourth embodiment of the invention, FIG. 8 is a cross-sectional view of the device of FIG. FIG. 7 along axis VIII-VIII, when the axis of the journal is aligned with said axis VIII-Vπi,

FIG. 9 illustrates an exploded and partial perspective view of an exemplary embodiment for the embodiment of FIGS. 5 and 6, FIG. 10 illustrates a different embodiment for a connecting element to be used, in particular, in the embodiments of FIGS. 5, 6 and 9, and

Figure 11 is an axial view of a piston whose articulation with the swing plate nt is offset laterally with respect to the axis of said piston.

FIGS. 1 and 2 show the general architecture of an axial piston pump, designated by the general numerical reference 1. The pump 1 comprises a tubular casing 2, of axis 3, delimited axially by a cover 4 On the axial side opposite to the lid 4, the pump 1 can either comprise a lid (not shown) inside which are mounted elements allowing the introduction and the delivery of a fluid inside said pump, either include elements arranged symmetrically with respect to a plane referenced 5.

Rolling bearings, here two in number and referenced 6 and 7, are respectively mounted inside the cover 4 and the casing 2. Said rolling bearings allow the mounting of a rotating shaft 8, with axis 9, an axial end of which is here projecting axially with respect to the cover 4. The axis 9 coincides with the axis 3 of the casing 2.

A sealing element 11 is mounted inside the cover 4 and is substantially flush with an outer cylindrical surface of the shaft 8.

The shaft 8 comprises, substantially at its center, a first portion 12 of large diameter provided with an oblique end surface 12a disposed axially on the side of the cover 4. The shaft 8 also comprises a crankpin 13, or arm, extending from the end surface 12a towards said cover. The crankpin 13 extends along an axis 14 inclined with respect to the axis 9. An angle α formed between said concoura axes 9 and 14 is here substantially equal to 14 °. Of course, it is also possible to envisage an angle α of different value, but being strictly greater than 0 ° and less than 90 °.

The shaft 8 also comprises a second part 15, axially extending the crankpin 13, considering the axis 9, the side opposite to the portion 12. Said portions 12, 15 have substantially equal diameters. Of course, for convenience, the parts 12, 15 and the crankpin 13 of the shaft 8 may not be made in one piece. Inside the housing defined by the casing 2, are formed several cylinders 18 regularly distributed over a circumference and extending axially along an axis 19 parallel to the axis 3. Pistons 21 are mounted inside the cylinders 18 , tightly. In the vicinity of an axial end projecting from the cylinder 18, each piston 21 comprises a bore 22, of axis 22a, extending transversely along the piston 21 and a recess 23 perpendicular to said bore 22. 22a of the bore is thus perpendicular to the axes 9 and 19, the axis 22a being concurrent with the axis 19.

To carry out the transformation of the rotational movement of the shaft 8 into reciprocating translation movement of the pistons 21, the pump 1 comprises in particular a connecting element mounted, slidingly, inside the bore 22 of axis 22a, made here in the form of a cylindrical body 24, or axis. The body 24 or axis is here supported over its entire length by said bore 22. This allows, with respect to an axis supported at its ends, not to stress the axis in bending and to increase the bearing surface di minuant thereby the pressure on the friction surfaces.

The body 24 is provided with a bore 24a passing right through said body 24 and oriented in the direction of the crankpin 13 of the shaft 8. The axis of the bore 24a is concurrent and perpendicular to the axis of the body 24 and located in the median plane of said body 24. Advantageously, the axes 9, 19 and 24a are located in the same plane, the axis of the cylindrical body 24 being perpendicular to this plane and to the axis 19.

The pump 1 also comprises a swash plate 25 mounted around the crank pin 13 and provided with a bore 26 fitted on a friction pad with cheeks forming a smooth bearing 20 so as to allow said swash plate 25 to rotate relative to said The rocker plate 25 extends axially along the crankpin 13 to the vicinity of the end surface 12a of the portion 12 and an end surface of the portion 15. The plate 25 is here in the form of an axle ring 14. The bearing 20 is also shaped to allow a sliding contact between the swash plate 25 and the parts 12 and 15 of the shaft 8.

From a peripheral surface of the plate 25, trunnion-shaped shafts 27, of axis 28, here extend radially outwardly. In other words, the axis 28 of the tower 27 is perpendicular to the axis 14. The journals 27 are here diametrically opposed. Each of the journals 27 is slidably mounted within the bore 24a of the body 24. The free radial ends of the journals 27, considering the axis 14, here are slightly protruding from the outer cylindrical surface of the body 24.

Advantageously, the axis 28 of each pin 27 passes through the instantaneous center of rotation of the swash plate 25, referenced O defined by the point of intersection of the axes 3 and 14. It is also conceivable to provide an axis 28 slightly offset relative to at said point O, of the order of one millimeter, this difference being absorbed by the free movement of the journals 27, the body 24 and the piston 21 relative to one another. The journals 27 are mounted here with lateral play relative to the pistons 21, which is schematically illustrated by the arrow 29.

To immobilize in rotation the oscillating plate 25, said plate here comprises a guide finger 30 extending radially outwardly relative to a peripheral surface of said plate 25, the axis of said finger 30 thus being perpendicular to the axis 14 of the crank pin 13. The finger 30 is mounted inside a slide 31 arranged at the level of the casing 2 and whose axis is preferably parallel to the axis 19 of displacement of the piston 21. Said finger 30 thus makes it possible to fix in rotation the swash plate 25 and to define the trajectory of the journals 27.

In an alternative embodiment, it is also conceivable to replace the guide of the swash plate by said finger by a guide via a piston, eliminating the possibility of sliding of the connecting element relative to said piston, I trunnion corresponding to the connecting element thus playing the role of the guide pin, and the axis 19 of the piston 18 corresponding to that of the slide. In operation, during rotation of the rotating shaft 8, each pin 27 is driven, on the one hand, by an angular movement of plus or minus α relative to an axis passing through the point O and perpendicular to the axis 9 of the shaft 8, which generates a rotation of the body 24 around the axis 22a, and secondly, an angular rotation on itself of plus or minus α about the axis 28. The displacement of the journals 27 thus makes it possible to obtain an alternative movement of the pistons 21 along the axis 19.

Furthermore, the angular movement described above, and illustrated schematically by the arrow 32, combined with the reciprocating displacement of the pistons 21 along the axis 19 generates a sliding of the journals 27 inside the bore 24a of the body 24 correspondent. This movement of a sliding pin 27 combined with its angular rotation movement on itself gives a waving movement of the pin 27 in the bore 24a.

Of course, it is also conceivable to provide, depending on the desired application, a running motor in an inverse mode in which a reciprocal rectilinear displacement of the pistons causes a rotation of the shaft.

The embodiment illustrated in FIGS. 3 and 4 differs in that each connecting element comprises a body 33 provided with a guide portion 34, formed here in the form of a parallelepiped, comprising a bore 35 at the The guide portion 34 extends substantially along the spigot 27.

The connecting element further comprises two axes 36 and 37 extending from parallel faces of the parallelepipedal guide portion 34 along a common axis 38 substantially perpendicular to the axis 28 and the displacement axis 19. Pistons 21. The connecting element thus forms a criss-cross. Each piston 21 here comprises, at one end projecting axially with respect to the cylinder 18, two guide portions 21a and 21b forming a cavity adapted for said body 33 and provided respectively with two bores 39 and 40 inside which are mounted the axes 36 and 37. The guide portion 34 is mounted axially, considering the axis 38, between the portions 21a and 21b with a slight operating clearance, shown schematically by the arrow 41, so as to allow sliding axes 36 and 37 along the axis 38. This same game is, of course, also provided between the ends of the axes 36 and 37 and the walls of the cylinder 18.

The embodiment illustrated in FIGS. 5 and 6, as well as in FIGS. 9 to 11, differs in that each piston 21 comprises at an axial end 21c, projecting from the cylinder 18, a planed portion 21c provided with a recess 42 of substantially rectangular shape. The planed portion 21c is defined between two planed faces 211 substantially parallel to each other and to the axis 19 of the piston. The eviction 42 extends transversely with respect to the direction of movement of the piston 21. The recess 42 opens through each planed face 121, through a respective opening 421. It is delimited transversely to the axis 19 by the openings 421 and, between the openings, by two opposite planar portions 42a and 42b. The recess 42 is delimited axially, that is to say in a direction parallel to the axis 19 of displacement of the pistons 21, by cylindrical portions 42c and 42d. The openings 421 are therefore delimited between the opposed flat portions 42a and 42b and the cylindrical portions 42c and 42d. The openings 421 have a length L42, measured axially and a height H42, measured perpendicular to the plane of FIG. 5. The distance between the openings 421, that is to say between the planed faces 121 opposite, is referenced D42.

The term "planed surface" or "planed portion" does not necessarily refer to a planing machining mode, but essentially to their recessed arrangement with respect to the general shape of the moving part.

A connecting element 43 is mounted here inside the recess 42 and comprises a parallelepipedal body 44 in conformance with said recess 42. The body 44 extends longitudinally along an axis 44a substantially perpendicular to the direction of rotation. displacement of the piston 21 and the axis 28 of the pin 27. The body 44 thus comprises, in a direction perpendicular to the axis 19 of movement of the pistons 21, two opposite outer faces forming cylindrical portions centered on the axis 44a and thereby allowing the rotation of said body 44 about said axis 44a. Thus, the connecting element can also be defined as a truncated cylinder portion along two flats 43a parallel to each other and to the axis 19. The distance between the two flats is referenced D43 and the height of the part, measured perpendicularly in the plane of Figure 5, is referenced H43.

The body 44 is shaped so as to slide slightly along the axis 44a inside the recess 42, between the flat faces 42a, 42b, for example of the order of a few millimeters, through a game 45. The clearance 45 is equal to half the difference H43 minus H42.

The body 44 comprises a bore 46, pierced between the two flats, and here perpendicular to said flats 43a and said axis 44a, bore inside which is mounted the pin 27.

In an advantageous embodiment, the value of the distance D43 is smaller than that of the length L42. Thus, particularly in the embodiments of FIGS. 5, 6 and 9 to 11, it is easy to introduce a connecting element transversely into the corresponding recess, through one of the openings. It is then sufficient to rotate the connecting element about the axis 44a to bring it substantially in the position of Figure 5. Once the pin 27 introduced into the bore 46, the connecting element is maintained in taken in the recess of the piston 21. A lateral opening 211 is sufficient to introduce transversely both the connecting element 43 in the planed portion 21c of the piston 21 and the pin 27 in said connecting element. Thus, unlike the prior art, it is not necessary to make orifices perpendicular to each other and to the axis of displacement in the axial end of the piston forming a hinge portion of the piston, some of the orifices being provided for the introduction and articulation of a connecting element and others for the introduction of the trunnion. Such a provision significantly weakened the articulation portion of the prior art and therefore requires that this portion of articulation is of significant size. This has the effect of significantly increasing the size of a motor or pump thus produced, but also to increase the mass of moving parts, so the inertial forces, which degrades the performance of these machines.

On the other hand, the fact of using the same opening 211 makes it possible to keep, on either side of the opening, solid posts 121 of large section, which are therefore resistant, without as much increase the dimensions of the planed portion 21c. In particular, the transverse dimensions of the planed portion may remain less than or equal to the diameter of the piston head. This also allows to guide the piston, or the moving part, over its entire length, which then moves in a liner of constant diameter. This possibility of guiding the piston at the level of the connecting element makes it possible to better take up transverse forces in the direction of movement of the piston, and resulting, for example, from the angular displacement of the trunnion. In addition, the cantilever between the plate and the piston, and the forces on the trunnion, are all the weaker as the piston is smaller and that its axis 19 can be close to the axis 9 of the piston. 8. The uprights 121 carry the flat surfaces 42a, 42b.

Also, unlike the cases of the prior art using a connecting element shaped spider or sphere, it is not necessary to make a removable piston.

As particularly illustrated in FIG. 9, it is also conceivable to provide, in order to facilitate the machining of the piston 21, a recess 142 inside which, on two opposite sides, bearings 242, for example made of bronze, are provided. of cylindrical portions corresponding in shape with the connecting element 43. The pads each comprise a wing 242a for resting on one of the planed faces of the planed portion 21c, for positioning and / or fixing, for example by screwing or solder, bearings relative to the planed portion 21c of the piston 21. Particularly in this embodiment, if the connecting member 43 is first introduced between the bearings 142, then, together with the bearings in the piston 21, this connecting element may not have flats and be substantially cylindrical in shape.

In an alternative embodiment illustrated in dashed lines in FIG. 9, the pads 242 may each comprise two wings spaced from one another by the distance D42, so that the pads may be fitted on the planed portion 21c, and then the connecting element is introduced between the pads. Once thus mounted the bearings are held transversely by their respective wings and axially by the presence between them of the connecting element. As particularly illustrated in Figure 10, the two flats 43s are not necessarily parallel. Thus, in the case of a motor piston, the forces exerted on the connecting element during the explosion are stronger on the surface of the connecting element closest to the piston head. It can therefore provide a smaller bearing surface, so a reduced distance D43R between the flats on the part of the element 43 remote from the combustion chamber. This arrangement can be reversed in the case of a pump. Such a configuration can significantly reduce the mass, therefore the inertia, of the connecting element.

In the embodiment illustrated in FIG. 11, the planed portion 21c is offset laterally relative to the axis 19 of the piston 21. Such an arrangement is particularly advantageous for increasing the diameter of the swash plate and modifying the forces and reactions to the right of the trunnion. A similar technique of offset of the axis of the pistons is particularly used in the case of crankshaft engines.

In addition, by limiting the thickness of the planed portion, ie the distance D42 between the two planed faces 211, it is possible to reduce the distance between the base of the pin and the point of application of the applied forces. by the piston on the trunnion, which reduces the constraints of embedding the trunnion in the plate. By decreasing the distance D42, the possibility of laterally shifting the planed portion, and hence the axis 44a relative to the axis 19 of the piston, is further increased.

In an alternative embodiment, the guidance of the swash plate 25 can be omitted by the finger 30 and can be replaced beforehand by reducing the lateral clearance 45 to a value of minimum play of operation on a piston 21, said piston making it possible to stop rotating the swash plate 25.

The embodiment of FIGS. 5, 6 and 9 to 11, comprising a connecting element provided with a body comprising such cylindrical portions, makes it possible, for the same piston diameter, to position a wheel at the connection element. 1 having a large diameter, having bearing surfaces of the connecting element on the piston important, in relation to the efforts to be taken, to support the entire length of the connecting piece and to easily perform, on a piston, stopping the rotation of the swash plate. This also makes it possible to take up the different transverse forces (reaction on the trunnion, torque, etc.) by guiding the piston to the right of the evacuation 42, the connecting element 43 and the trunnion 27. In an alternative embodiment, it is also conceivable to provide a piston provided at one axial end with a recess in the form of a ball joint, the connecting element being here provided with a spherical body which corresponds in shape with the ball joint and intended to to cooperate with the recess of the piston. However, such a variant does not allow the sliding of the connecting element relative to the piston.

The embodiment illustrated in FIGS. 7 and 8 differs from the embodiment illustrated in FIGS. 1 and 2 in that each pin 27 comprises stops 47, 48 arranged so as to allow the body 24 to be locked in translation relative to said pin. , and in that each piston 21 comprises, at one axial end, a recess 49. The junction between the pistons 21 and the body 24 is made here by a connecting rod 50 articulated at one end to said body 24 about the axis. 22a, by means of a rod head 51 in shape matching said body 24, and articulated at a second end (not shown) about an axis 53 parallel to said axis 22a, or hinged on a ball joint to remedy to possible geometrical defects of manufacture, mounted in the inside of the recess 49 of the piston 21, via a small end.

Of course, it is also conceivable to provide the use of such a connecting rod with a connecting element made in the form of a cross or, of course, in the form of a parallelepiped body as described above with reference to FIGS 5, 6, 9 and 10, the freedom of sliding along the axis 22 has been eliminated, considering FIG. 7. The use of the body of a spherical body with such a connecting rod does not require any particular arrangement for as regards the sliding along the axis 22a, but has the particularity of allowing freedom of rotation of the connecting rod about its longitudinal axis. In all cases, it will be necessary to fix the swivel plate in rotation. The device for reversibly transforming a rotational movement of a shaft rotating about an axis of rotation in reciprocating rectilinear motion of a moving part in a direction parallel to said axis of rotation has the advantage of including particularly easy elements. to manufacture and adapt according to the application of the device, while allowing to achieve a simple connection, robust and accurate between a swash plate and a moving part.

Of course, in a certain measure, the axes of displacement of the pistons are not necessarily parallel to each other and / or to the axis of rotation of the shaft. This is due to the proper operation of the junction formed by the trunnion, the connecting element and the moving part.

Claims

1. Device (1) with a swashplate (25), said plate being pivotally mounted on a rotating shaft (8) capable of rotational movement and connected to at least one moving part (21) in a rectilinear motion, for transforming one of said movements into the other, said device further comprising a connecting member (43) forming a hinge with said swash plate and said moving part, said plate comprising a trunnion (27) engaged with the element link, this element being housed in a recess (42) adapted to the moving part, the movable part comprising a lateral opening (421) for transversely introducing the connecting element (43) and the pin, through the same opening ( 421).

2. Device according to claim 1, characterized in that the recess (42) of the movable part (21) is delimited, in the moving direction of the moving parts, by the cylindrical portions (42c, 42d) and, between the cylindrical portions, through the openings (421) formed in planed faces (211) opposite the moving parts, the openings being separated

20 between them by two full uprights (121).

3. Device according to claim 2, characterized in that the opposite planed faces (421) are parallel to each other.

4. Device according to claim 2 or 3, characterized in that the cylindrical surfaces (42c, 42d) of the movable part (21) are carried by insert pads (242) on said moving part.

5. Device according to one of claims 2 to 4, characterized in that it comprises a clearance (45) between the connecting element (43) and the amounts (121).

6. Device according to claim 5, characterized in that it comprises at least two moving parts of which only one is such that the connecting element (43) of said movable part is adjusted between the uprights (121) of said moving part. the at least one other moving part being such that there is a clearance (45) between the connecting element (43) and the uprights (121) of the said other moving part.

7. Device according to one of claims 5 or 6, characterized in that the connecting element comprises cylindrical surfaces provided to cooperate with the cylindrical surfaces of the recess, so that the element is rotatably mounted around an axis (44a) substantially perpendicular to the displacement of the moving part.

8. Device according to claim 7, characterized in that the connecting element is formed of a cylinder portion truncated by two flats (43a) substantially parallel to the axis (44a) of said cylinder.

9. Device according to claim 8, characterized in that the flats (43a) are substantially parallel to each other.

10. Device according to claim 8, characterized in that the flats (43a) are not parallel to each other, so that one of the cylindrical surfaces of the connecting element is narrower than the other.

11. Device according to one of claims 5 to 10, characterized in that the connecting element further comprises a bore (46) pierced between the two flats, to introduce the trunnion.

12. Device according to one of claims 5 to 11, characterized in that a minimum length (L42) of the openings (421), measured according to the moving direction of the moving parts is greater than or equal to a maximum distance (D43) between the flats.

13. Device according to one of claims 1 to 12, characterized in that the pin (27) forms a sliding pivot connection with the connecting element

(43).

14. Device according to one of claims 1 to 12, characterized in that the movable part comprises a connecting rod in which is formed the recess, the pin being locked in translation in the connecting element.

15. Machine, especially motor for automotive vehicle, compressor or pump, Equipped with a device according to one of claims 1 to 14, said movable part comprises a piston.

16. Machine according to claim 13, characterized in that it is provided with two oscillating plates disposed symmetrically with respect to a median plane and each comprising at least one trunnion, and pistons arranged in the same cylinder symmetrically with respect to said median plane.

17. Machine according to claim 14, characterized in that it comprises means for bringing the two trays oscillating.