FR3050773A1 - DEGRASABLE HYDRAULIC MACHINE AND VEHICLE EQUIPPED WITH SUCH A MACHINE - Google Patents

Abstract

The present invention relates to a radial piston hydraulic machine comprising a housing (110) defining a first assembly and a shaft (130) defining a second set free in rotation relative to each other, a multilobed cam (114), a distributor (140), a cylinder block (120), rotational engagement means (150) of the cylinder block relative to the second assembly, the distributor (120) being translatable relative to the housing (110) to ensure a function of clutch and disengagement respectively of the engagement means (150), characterized in that the distributor (140) comprises at least one sealing means (146) formed of an open annular segment having two sections ( 220, 230) inclined relative to the central axis (202) of the segment and relative to its transverse plane of symmetry (204), the two sections (220, 230) being offset in the peripheral direction and each covering a portion only from thickness of the segment.

Description

GENERAL TECHNICAL FIELD The invention relates to the data of disengageable hydraulic machines. The invention applies in particular to hydraulic machines with radial pistons.

STATE OF THE ART

The disengagement of a hydraulic machine can be sought for different purposes.

For different types of application, it is for example known to use hydraulic machines to generate a torque at the wheels of a vehicle.

This hydraulic assistance is however not always desired and it may be desirable to temporarily set the wheel "free wheel". To this end, there are disengageable hydraulic machines.

FIGS. 1 and 2 show the general structure, according to a longitudinal axial section and a cross section respectively, of an example of a known disengageable hydraulic machine, for example from document WO2014 / 048842.

The hydraulic machine 100 shown in Figures 1 and 2 attached comprises, centered on a longitudinal axis XX, a housing 110, a distributor cover 112, a cylinder block 120, a shaft 130, a distributor 140, a clutch 150 and a cam lobed 114.

The distributor 140 is mounted free of a certain deflection or axial movement to allow disengaging / engaging the engine.

More specifically, the cylinder block 120 preferably comprises a plurality of radial pistons 122 housed in respective cylinders 124 oriented radially relative to the central axis X-X. The pistons 122 can move in radial translation in the respective cylinders 124. Each piston carries, at its end adjacent to the lobed cam 114, a roller 126 resting on the lobed cam 114, so that the rollers 126 above roll on the Lobed cam 114. Generally, bearing springs 128, respectively placed in each cylinder 124, continuously push each piston 122 and its associated roller 126 bearing against the lobed cam 114.

Hydraulic machines of the type illustrated in Figures 1 and 2 may be subject to many variants.

They can be either the rotating shaft type or the rotating casing type.

They may also have an outer multilobed cam 114 and a cylinder block disposed on the inside of the cam 114, or conversely an internal multi-lobed cam 114 and a cylinder block disposed on the outside of the cam 114.

The housing 110 and the shaft 130 are always rotatably mounted relative to each other.

In an external cam machine, the cam 114 is connected to the housing 110, while the cylinder block 120 is free with respect to the housing 110 and can be engaged in rotation with the shaft 130. The hydraulic inlets and outlets of the distributor 140 open always in a fixed part.

In one configuration the cam 114 can be secured to the fixed frame and in this case the cylinder block 120 drives the shaft 130 in rotation relative to the fixed frame.

Alternatively the shaft 130 may be secured to the fixed frame and in this case the cylinder block 120 drives the cam 114 and the casing 110 in rotation relative to the fixed frame. Those skilled in the art knows internal cam configurations and knows how to adapt accordingly the layout of the various elements making up the machine. In some configurations the engagement means are then no longer provided between the cylinder block and the shaft, but between the cam and the shaft.

Whatever the configuration adopted, the cylinder block 120 is rotated relative to the housing 110 during operation.

Bearings 115, 116, for example of the conical roller type or ball bearing, are arranged at the ends of the machine. to allow the relative rotation of the shaft 130 and possibly resume the efforts.

The distributor 140 most often comprises two ducts 142, 144 configured to supply the cylinder block 120 with oil or to discharge the oil from the cylinder block 120. Generally, inside these ducts 142, 144, the oil is under a high pressure of about 400 bar when it comes to the supply pressure, under a low pressure of about 100 bars when it is a discharge pressure, and a pressure of feeding of about 20 bar when it comes to feed the machine 100 in the moments prior to its operation.

More specifically, the conduits 142, 144 above each comprise a portion disposed between the distributor 140 and the distribution cover 112, acting as a thrust chamber. These portions include an effective S142, S144 section that can generate a longitudinal force when pressure is applied.

The dispenser 140 includes seals 146 at the interface with the dispenser cover 112.

The distributor 140 generally has a stepped shape approaching the cylinder block 120. This stepped shape facilitates the implementation of the aforementioned thrust chambers.

It is thus preferably provided a seal 146 between each stage of the dispenser 140 and the cover of the distributor facing also staggered in a complementary manner.

More precisely according to FIG. 1, three gaskets 146 are provided.

A rod referenced 148 in FIG. 1, can enable the indexing in rotation of the distributor 140 relative to the distributor cover 112. The clutch 150 makes it possible to join or separate the shaft 130 with the cylinder block 120 and thus to switch respectively between a drive configuration or a freewheel configuration. The clutch 150 generally comprises a plurality of disks 152 integral with the shaft 130 or a radial extension 132 thereof and a plurality of disks 154 integral with the cylinder block 120.

The disks 152 and 154 are arranged alternately and can, when they are pressed onto each other, transmit a torque.

For this, the cylinder block 120, like the distributor 140, is movable longitudinally in translation which makes it possible to tighten and loosen the clutch 150.

The aforementioned translation is caused by the distributor 140, which itself is movable longitudinally in translation along the axis XX under the effect of the pressure in the conduits 142, 144. Indeed, the thrust chambers of the conduits 142, 144 are designed so that the pressure generates a force exerting in the longitudinal direction X. This is typically the feeding pressure which is used to cause the clutch of the machine 100.

When it is desired to disengage the machine, the conduits 142, 144 are evacuated, that is to say connected to an oil reservoir whose pressure is low. Nevertheless, to ensure that the clutch 150 is discarded, it is known to use a disengagement spring 160 disposed between the cylinder block 120 and the casing 110. This spring 160 tends to move the cylinder block 120 away from the extension radial 132 connected to the shaft 130, to disengage the machine 100.

In known hydraulic machines, the seal between the distributor 140 and the cover of the distributor 112 or the element of the associated casing is generally achieved by seals 146 and counter-seals.

Overall hydraulic machines thus formed are satisfactory.

However, they have the disadvantage that the aforementioned seals and counter-joints induce a high coefficient of friction, which implies having to apply a large force to move the distributor 140, and therefore requires to increase the force-feeding pressure relative to to conventional machines, not disengageable.

Different solutions have been proposed for this purpose. A solution is for example described in the document FR 3019594. It essentially consists in providing an additional thrust chamber associated with the distributor 140. The use of such an additional thrust chamber is of interest. However, to limit the force exerted by the dispenser, exposed to the maximum pressure, it is often useful to add an additional valve limiting pressure. This valve, of the reverse selector type, connects the throat of the additional thrust chamber to the low pressure line of the system.

Such a solution therefore has the disadvantage that the addition of the additional thrust chamber, combined with the additional valve, increases the price of the complete system and therefore lower the competitiveness of the system in economic terms.

The problem arises from the fact that in disengageable hydraulic machines of the aforementioned type, the distributor 140 must perform two functions, one which is to ensure the distribution of oil necessary to operate the hydraulic machines and which requires that the leaks are minimized and the other which is to ensure the commitment of the system by an axial movement of the distributor 140 and which requires that the friction forces between the distributor and the dispenser cover or the associated housing element, are also minimized .

PRESENTATION OF THE INVENTION

In this context, the object of the present invention is to improve the state of the art by proposing new means which make it possible both to limit the coefficient of friction between the distributor 140 and the dispenser cover 112 and to improve the hydraulic sealing.

The aforementioned objects are achieved in the context of the present invention with a radial piston hydraulic machine comprising: - a casing defining a first set. a shaft defining a second assembly, said first and second assemblies being free to rotate with respect to each other, a multi-lobed cam, a distributor, a cylinder block mounted free to rotate relative to the first together, means for rotationally engaging the cylinder block with respect to the second assembly, the distributor being capable of translation relative to the housing to provide a clutch function and disengagement of the engagement means so as to engage and respectively disengaging the cylinder block in rotation with the second assembly, characterized in that the distributor comprises at least one sealing means formed of an open annular segment having two cuts inclined with respect to the central axis of the segment and relative at its median transverse plane of symmetry, the two cuts being offset from each other in the peripheral direction and each covering only a portion of the shoulder segment.

In other words, according to the invention the segment comprises a beveled cut in two planes.

PRESENTATION OF THE FIGURES Other characteristics, objects and advantages of the present invention will appear on reading the detailed description which follows, and with reference to the appended drawings, given by way of non-limiting examples and in which: FIG. 1 previously described is a longitudinal axial sectional view of the general structure of a disengageable hydraulic machine according to the state of the art, but whose general structure can be retained within the scope of the invention, - Figure 2 also previously described is a cross-sectional view of the same machine that can be used in the context of the invention, according to a transverse sectional plane at the cylinder block. FIG. 3 represents a general perspective view of a sealing segment according to the present invention, FIG. 4 represents an enlarged partial view of the identified detail IV in FIG. 3, of a sealing segment conforming to FIG. the present invention at its cutting, - Figure 5 shows a view similar to Figure 4, but with partial tearing of the material of the segment on a zone referenced A to better illustrate the geometry of the cut, - Figure 6 is a radial sectional view of the segment according to the section plane VI-VI referenced in Figure 3, - Figure 7 shows a view similar to Figure 4 of a variant of a segment according to the present invention comprising a structure of hooks facilitating installation, - Figure 8 shows the variant of Figure 7 in the closed position of the segment by engagement of the hooks, - Figure 9 shows an alternative embodiment of a segm According to the present invention having another embodiment of hook structure facilitating the installation, in the open position similar to Figure 7, - Figure 10 shows the variant of Figure 9 in the closed position of the segment by bets. in engagement with the hooks, - Figures 11 and 12 show two partial perspective views of another alternative embodiment of a segment according to the present invention, - Figures 13a, 13b, 13c and 13d show schematically a manufacturing process of the segment according to the present invention, and - Figure 14 shows a longitudinal axial sectional view similar to Figure 1 of a variant according to the invention that the segments are placed in grooves formed in the distributor cover and not in distributor grooves.

DETAILED DESCRIPTION

The general structure of the disengageable hydraulic machine according to the invention can be the subject of many variants and is preferably of the type shown in Figure 1. It will therefore not be described in detail later. The entirety of the foregoing description made with reference to FIGS. 1 and 2 must be considered as applicable to the machines in accordance with the invention and consequently incorporated in the description of the invention. The invention, however, preferably applies to the machines with multi-lobed outer cam 114 connected to the casing 110 and to inner cylinder block 120 connected to the shaft 130 by means of engagement means, the machine being in addition to shaft rotating or rotating case.

In the following description, we will focus on describing the structure of the segment 200 according to the invention.

This segment 200 may be used to replace at least one of the seals 146, and preferably the three seals 146, shown in FIG. 1, disposed in grooves formed on the outer surface of the dispenser 140 and therefore resting on the surface next to the dispenser cover 112.

Alternatively, the segment (s) 200 according to the invention can be placed in a groove or groove formed on the inner surface of the dispenser cover 112 and resting on the surface. external facing the dispenser 140, as shown in Figure 9.

The segment 200 shown in the appended FIG. 3, according to the present invention, is formed of a ring centered around a central axis 202. This axis 202 is coaxial with the main X-X axis of the machine when in use. The segment 200 has a mean transverse plane of symmetry 204 perpendicular to the axis 202. The segment 200 is not closed. It is instead open on part of its periphery in the form of a through cut 210.

The term "through" means that the cutout 210 covers the entire radial extension of the ring 200 as well as the entire height or longitudinal thickness parallel to the axis 202 of the ring 200.

The term "average plane of symmetry" means that the segment 200 comprises two parts located respectively on either side of the plane 204 transverse to the axis 202 and that these two parts are symmetrical to each other, except at the cutting level. 210. The ring 200 when it is tightened and that the edges of the cutout 210 are contiguous, takes a closed position tightened 360 °. However, at rest, the ring takes an expanded position in which the cutout 110 is open. The segment 200 is thus likely to change in the value of its outer radius, which allows to press the segment 200 against the facing surface and thus ensure sealing.

The segment 200 is preferably made of metal.

Its cross section, along a radial plane passing through the axis 202, can be the subject of many variants. If necessary, this cross section could be rounded, for example circular. However, preferably, the cross section of the segment 200 is formed of a polygon, more precisely still of a square or rectangular section whose main edges are respectively parallel to the axis 202 for the radially inner cylindrical facets 240 and radially respectively. external 242 and parallel to the transverse median plane 204 above and therefore orthogonal to the axis 202 for the axial facets 244, 246 in the form of a crown.

As previously indicated, according to the invention, the cutout 210 is formed not of a simple cutout in a radial plane passing through the axis 202, but is formed of two oblique cuts 220, 230 inclined with respect to the central axis 202 and relative to the transverse median plane 204.

Moreover, the two sections 220, 230 are offset with each other in the peripheral direction.

The facets formed by the cutout 220 on the ends facing the segment are referenced 222 and 224.

The facets formed by the cutout 230 on the ends facing the segment are referenced 232 and 234.

Each of the two facets 222, 224 and 232, 234, respectively, of the two sections 220, 230 may be planar or not, for example curved, convex or concave and preferably complementary respectively. In the constricted position of the segment 200, the two facets 222, 224 and 232, 234 of each section 220, 230 are contiguous and preferably perfectly complementary. Thus the facet 222 is complementary to the facet 224 and in the constricted position of the segment 200, the facet 222 rests on the facet 224. Respectively the facet 232 is complementary to the facet 234 and in the constricted position of the segment 200, the facet 232 rests on facet 234.

Each of the two cutouts 220, 230 extends over only a portion of the thickness of the segment, but over the entire radial extension of the segment.

Typically, each of the two oblique cuts 220, 230 extends over half the thickness of the segment 200.

And the two oblique cuts 220, 230 are interconnected by a section, preferably flat and located in the median plane of symmetry 204.

Due to the peripheral angular offset defined between the two sections 220, 230 and the median section which connects them, it is formed on the respective ends of the segment 200 two bars 228, 238 generally parallel to each other which end respectively with the facets 222 and 234 above.

As seen in Figure 4, it is thus formed between the two blanks 220, 230 facets 250, 252 opposite, in the form of ring sectors centered around the axis 202.

These facets 250 and 252 delimit the aforementioned bars 228 and 238. Those skilled in the art will understand that the particular segment structure according to the invention provides effective barrier against leakage and thus ensures a good seal. On the one hand, the cooperation defined between the facets 222, 224 and respectively 232, 234 opposite each cutout 220, 230 makes it possible to define a barrier peripheral to the fluid irrespective of the angle of opening of the segment. On the other hand, the peripheral angular offset defined between the two cutouts 220, 230 forming two facing bars 228, 238 defines an axial barrier to the fluid.

In other words, the combination of the two cutouts 220, 230 and the peripheral and axial offset defined therebetween, generates a labyrinth with regard to the possible fluid flows on the periphery of the dispenser 140. Indeed, thanks to the particular cutting structure according to the invention, there is no direct passage for the fluid.

In the figures reference is made to the inclination of the section 220 with respect to a radial plane passing through the axis 202 and reference is made to β the inclination of the section 230 with respect to a radial plane passing through the axis 202 .

These angles o and β of inclination of the facets 222, 224 and respectively 232, 234 of the sections 220 and 230 with respect to a radial plane may be identical for the two cuts or different.

Preferably, the cutting facets 222, 224 and respectively 232, 234 are inclined with respect to a radial plane, at an angle of between 10 and 45®, very advantageously of the order of 30 °.

Furthermore, the angular offset Θ existing between the two sections 220, 230 with respect to the axis 202 is preferably between 5 and 20 °, very preferably of the order of 10 °.

More specifically, as seen in Figure 4, preferably the two sections 220, 230 are of opposite inclination.

By "opposite" is meant the fact that according to the representation given in FIG. 4, a first section 220 converges towards the radially outer face 242 in the trigonometric direction whereas the facets 232, 234 of the second section 230 converge towards the same radially outer face 242 in the direction of clockwise.

FIGS. 7 and 8 show an alternative embodiment according to which the segment 200 comprises structures 260 in the form of complementary hooks on the facing facets 250 and 252 of the bars 228 and 238.

Such hook-shaped structures can be the subject of many embodiments.

According to the non-limiting embodiment given in the accompanying FIGS. 7 and 8, a polygonal casing recess 262 is formed on the facet 252 and an additional projection 264 on the facet 250, respectively.

In the constricted position of the segment, the projection 264 can be placed in the recess 262, in order to keep the segment in a tight position and thus facilitate the mounting of the segment on the dispenser 140 or on the facing lid 112.

The hook-shaped structures 260 constituting a projection 264 and a recess 262 illustrated in FIGS. 7 and 8 are defined by generatrices transverse to the central axis 202 of the segment.

FIGS. 9 and 10 show an alternative embodiment of structures 270 in the form of hooks defined on the cutting facets 222, 224 and 232, 234, respectively, by generatrices parallel to the central axis 202.

According to FIGS. 9 and 10, these structures 270 are in the form of a hemicylindrical cap. However, the invention is not limited to this particular geometry. The structures 270 may for example be polygonal sections.

It is thus formed according to FIGS. 9 and 10, a concave hemicylindrical cavity 272 on the cutting facets 224 and 232 and convex hemicylindrical projections 274 respectively on the facing facets 222 and 234.

This solution is advantageous for mounting. Indeed the projections 274 / hollow 272 can maintain the constricted shape of the segment during assembly so that the segment remains in his throat and does not rub. And when first put into use, the pressure makes the two ends of the segment unclip and the segment is rubbing against the bore that receives it.

As shown in FIGS. 11 and 12, the facing facets 250 and 252 formed between the two cutouts 220, 230 and perpendicular to the axis 202 can be extended by slots 280, 282 extending in a mean plane perpendicular to the central axis 202. The slots 280 and 282 extend over the entire radial extension of the segment 200.

These slots 280, 282 make it possible to separate at mid-thickness each of the two ends of the segment in the form of two distinct elements juxtaposed axially, allowing independent deformation of these two end elements, and consequently improving the tightness of the system, in particular to improve the reduction of axial leaks, but also radial. By way of nonlimiting example, each slot 280, 282 may cover an angle of the order of 5 to 45 °, preferably 5 to 20 °, with respect to the central axis 202.

According to the embodiments illustrated in Figures 3 to 8, the cutting facets 222, 224, 232, 234 are generally planar.

FIGS. 11 and 12 also show an alternative embodiment according to which these cutting facets 222, 224, 232, 234 are concave. More precisely still, preferably, according to FIGS. 11 and 12, the curve of the facets 222, 224, 232, 234 is not symmetrical with respect to a median plane pm parallel to the central axis 202 and orthogonal to an external envelope ee planar plane corresponding to the plane facets illustrated in FIGS. 4 to 8 (in FIG. 11 is shown diagrammatically under the reference "ee" such a theoretical planar outer envelope and under the reference "pm" said aforementioned plane parallel to the central axis and orthogonal to the envelope ee): according to FIGS. 11 and 12, the facets 222, 224, 232, 234 of the cuts are connected substantially tangentially to the external envelope ee said theoretical plane on the end side of the segment segments and instead connect substantially perpendicular to the outer envelope ee said theoretical plane on the opposite side of the segment directed towards the solid part thereof.

The above non-planar but concave arrangement of the cutouts 222, 224, 232, 234 makes it possible to guarantee a good filling of the end of the segment in the case of a molding embodiment.

Furthermore, the concave shapes of the cutting facets 222, 224, 232, 234 make it possible to reinforce the labyrinth effect defined by the complementary cooperation of the ends of the segment 200 and consequently to reinforce the reduction of leaks.

The various aforementioned cutouts 220, 230 and, where appropriate, 280 and 282, necessary to form a segment 200 in accordance with the invention, may be formed by laser cutting.

As a variant, these cutouts 220, 230 and, where appropriate, 280 and 282 may be formed by mechanical cuts.

FIG. 13a shows a cutting step using a blade 300 moved at mid-thickness of the segment in a direction perpendicular to the central axis 202, radially with respect thereto, for producing the facets 250, 252 and, where appropriate, slots 280, 282.

The leading edge of the blade 300 may be concave 302, rectilinear 304 or convex 306.

FIG. 13b shows the step of making the oblique cutout 220 using a tool 310 moved parallel to the central axis 202 up to half the thickness of the segment.

FIG. 13c shows the step of producing the second oblique cutout 230 using a tool 320 moved parallel to the central axis 202 on the opposite side to mid-thickness of the segment.

FIG. 13d shows the segment obtained at the end of the aforementioned mechanical cutting steps. Figure 13d shows cutouts 220, 230 and slots 280 and 282.

The present invention also relates to vehicles equipped with a machine according to the invention.

Of course, the present invention is not limited to the particular embodiments that have just been described, but extends to any variant within his mind.

According to another embodiment of the segment according to the present invention illustrated in the accompanying figures can be achieved by axial juxtaposition of two open elementary rings whose openings are angularly offset.

Claims (11)

A radial piston hydraulic machine comprising: - a housing (110) defining a first set, - a shaft (130) defining a second set, said first and second sets being free to rotate with respect to each other, a multilobed cam (114), a distributor (140), a cylinder block (120) rotatably mounted relative to the first assembly, means for rotating the cylinder block (150) relative to the second cylinder; together, the distributor (120) being capable of translation relative to the housing (110) to ensure a clutch function and respectively disengagement engagement means (150) so as to engage and respectively disengage the cylinder block (120) in rotation with the second assembly, characterized in that the distributor (140) comprises at least one sealing means (146) formed of an open annular segment having two cuts (220, 230) inclined with respect to the axis central (202) of the segm and with respect to its transverse plane of symmetry (204), the two sections (220, 230) being offset in the peripheral direction and each covering only a portion of the thickness of the segment. 2. Machine according to claim 1, characterized in that the cutting angles (o, β) of the two sections (220, 230) are identical. 3. Machine according to claim 1, characterized in that the cutting angles (o, β) of the two sections (220, 230) are different. 4. Machine according to one of claims 1 to 3, characterized in that each cutting facet (222, 224, 232, 234) is inclined relative to a radial plane, a value between 10 and 45 ° , advantageously of the order of 30 °. 5. Machine according to one of claims 1 to 4, characterized in that the two cuts (220, 230) are offset by an angle (Θ) of 5 to 20 °, preferably of the order of 10 °. 6. Machine according to one of claims 1 to 5, characterized in that each cut (220, 230) extends over only a portion of the thickness of the segment, preferably substantially over half the thickness of the segment. 7. Machine according to one of claims 1 to 6, characterized in that the inclinations (a, β) of the two sections (220, 230) are opposite. 8. Machine according to one of claims 1 to 7, characterized in that the segment has hooks (260; 262, 264) at its sections (220, 230). 9. Machine according to one of claims 1 to 8, characterized in that the facets (222, 224, 232, 234) of each section (220, 230) are concave. 10. Machine according to one of claims 1 to 9, characterized in that facets (250, 252) orthogonal to the central axis (202) separating the two sections (220, 230), are extended by slots ( 280, 282) separating in thickness each of the two ends of the segment in the form of two distinct elements juxtaposed axially, allowing independent deformation of these two end elements. 11. Vehicle characterized in that it comprises a disengageable hydraulic machine according to one of claims 1 to 10.