EP1941158B1 - Radial piston-type hydraulic motor with cylinder block cooling - Google Patents

Description

The present invention relates to a radial piston hydraulic motor comprising a housing, a cylinder block arranged in the housing so that the housing and the cylinder block are able to rotate relative to each other about an axis. and having a plurality of cylinders which extend radially relative to the axis of rotation and in which pistons are slidably mounted, a reaction cam for the pistons, and a fluid distributor, which is integral with the cam with respect to the rotation about the axis of rotation and which comprises distribution ducts adapted to connect a supply line or an exhaust duct to the cylinders.

The invention is more particularly concerned with the cooling of the cylinder block of an engine of this type. Indeed, during the operation of the engine, overheating occurs in various areas of the engine and, if they are not controlled, these overheating adversely affect the transmission of engine power and may even cause damage to certain parts .

These warmings are due to several phenomena. On the one hand, the pressure drops that occur in the hydraulic circuit in various areas of the engine cause elevations in the temperature of the hydraulic fluid. In addition, friction between some parts dissipates energy in the form of heat. This is in particular the friction of the pistons in the bores of their respective cylinders, or that of the fluid distributor vis-à-vis the cylinder block. It is also worth mentioning the parasitic friction couples, which affect the areas in which seals and rolling bearings are located. Finally, in general, fluid leaks in certain ducts, in particular at the junction of the distributor and the cylinder block, as well as in the cylinders, cause phenomena similar to pressure losses and also cause a rise in temperature. hydraulic fluid.

Certain areas of the engine are particularly affected by these heating phenomena. These are in particular the regions of the cylinder block and the pistons in which the friction between the pistons and the walls of the cylinders are the highest. The heating up in these areas can lead to an increase in the diameter of the pistons, and consequently cause local deformations of the latter which cause the section of a piston to no longer be precisely matched to that of its cylinder, which further increases friction and therefore heating. At the extreme, excessive heating can cause seizure of a piston in its cylinder and therefore irreversible damage to the cylinder block and the piston concerned, and usually the engine.

The ends of the pistons that are closest to the axis of rotation (turned towards the bottom of the cylinders) are normally permanently in contact with the supply or exhaust fluid. Thus, these end regions of the pistons are properly cooled.

However, the friction relates more particularly cylindrical surfaces in contact between the pistons and the cylinders. More particularly, in the case of a radial piston engine, the friction is greatest in the vicinity of a radial plane (perpendicular to the axis of rotation), in which the diameters of the pistons can be measured.

In the prior art, attempts are known to improve the cooling of the cylinder block, consisting mainly of increasing the exchange surface between the cylinder block and the fluid present in the engine casing. Indeed, according to these solutions, one or more faces of the cylinder block have notches or grooves which form between them surfaces behaving as cooling fins. There are also known systems for scanning the crankcase of the engine with an exchange fluid. This exchange fluid is taken from the fluid supply and exhaust system of the engine and cooled before being re-introduced into the circuit. This exchange fluid can be used to sweep the crankcase space and cool the parts it contains.

However, in these solutions, only one or more outer surfaces of the cylinder block are really concerned by the cooling, while the risk of heating in more central regions of the cylinder block, particularly in the vicinity of the radial plane mentioned above, remain important.

Patent is also known US 3,151,529 a cylinder block having axial holes.

In this context, the invention aims to provide a hydraulic motor for which the cooling of the cylinder block is improved.

This object is achieved thanks to the fact that the cylinder block has scanning holes, which are formed between two consecutive cylinders, and which open at least two openings in two pressure zones different from the periphery of the cylinder block, each hole at least partly extending at least in the vicinity of a radial plane of the cylinder block in which the diameter of a cylinder adjacent to the hole in question and in the radial space of said cylinder is measured, so that fluid contained in the casing can circulate in the scanning hole in the vicinity of said cylinder to promote cooling of the wall of the latter in a zone passing through said radial plane.

The scanning holes of the invention are formed between the consecutive cylinders and are irrigated in sweeping fluid because the pressure difference between the two openings of a hole generates a flow of fluid in this hole. Indeed, the fluid tends to enter the scan hole through the opening in the vicinity of which the pressure of the fluid is the highest, and out through the other opening. This pressure difference in the vicinity of the two openings exists in operation of the engine, during the relative rotation of the cylinder block and the cam. It may be inherent in the operation of the engine and be simply due to the arrangement of the two openings and / or the addition of specific means such as deflectors in the vicinity of the openings. Each scanning hole extends between two consecutive cylinders, in the vicinity of the radial plane in which the heating is important and in the radial space of an adjacent cylinder, that is to say on at least a part of the height. of this cylinder. Consequently, these sweep holes allow the areas of the cylinder block more particularly concerned with the heating to be cooled and this cooling has an effect on the walls of the rolls and, therefore, on the pistons which slide against these walls.

The scanning holes have, over at least a portion of their length, a section that delimits a closed contour, so that they form enclosures in which the scanning fluid can flow. The scanning holes behave like real ducts, in which the flushing fluid circulates through them from one side to the other.

Advantageously, at least one sweeping hole, open on the axial periphery of the cylinder block opposite the axis of rotation and situated in the vicinity of a cylinder is asymmetrical with respect to the radial plane in which the diameter of the cylinder is measured.

During the relative rotation of the cylinder block and the cam, the fluid located in the vicinity of the axial periphery of the cylinder block opposite the axis of rotation tends to be driven tangentially. In the vicinity of the cylinders, the fluid flow tends to be distributed substantially symmetrically with respect to the radial plane in which the diameter of the cylinder is measured, generating two currents around the point of contact between the piston located in this cylinder and the cam. By positioning the scan hole asymmetrically with respect to this radial plane, the creation of a vortex phenomenon in the vicinity of this scanning hole is facilitated, which in turn favors the circulation of fluid in the scanning hole.

Advantageously, at least one sweeping hole formed between two consecutive rolls comprises two openings respectively located, on the axial periphery of the cylinder block opposite the axis of rotation, in the vicinity of each of said rolls.

In this case, during the relative rotation of the cylinder block of the cam, one of the openings is in front of one of the two cylinders while the other opening is behind the other cylinder. Due to the rotation, the fluid pressures contained in the casing in these two zones are different, which favors the circulation of the fluid in the scanning hole.

Advantageously, at least one scanning hole formed between two consecutive cylinders has two openings respectively located at each of the two axial ends of the cylinder block, and means are provided to promote the circulation of fluid in the scanning hole during the rotation. relative to the cylinder block and the crankcase.

As will be seen in the following, to promote the flow of fluid in the sweeping hole, it can be provided for example that the hole has at least one section inclined relative to the axis of rotation and / or a deflector is located in the vicinity of at least one of the openings of the sweeping hole, this deflector can be attached to the cylinder block or integrated therewith. This inclination and / or this reflector make it possible to ensure that the pressure of the fluid in the vicinity of the two openings is different.

Advantageously, at least one scanning hole comprises at least one opening located on the axial periphery of the cylinder block opposite the axis of rotation and an opening located on an axial end of the cylinder block.

For example, the sweeping hole may have a bent shape and two openings respectively located on the axial end of the cylinder block and on the outer axial periphery of the latter. A sweeping hole may also comprise a substantially rectilinear section which passes right through the cylinder block between its two axial ends, and an additional opening located on the outer axial periphery of the cylinder block. The openings are then located in very different areas of the cylinder block, so that the pressure in the vicinity of these openings is different. In particular, because of the relative rotation of the cylinder block and the cam, the pressure in the vicinity of the axial periphery of the cylinder block varies.

More specifically, because of the fluid volume variation included between the cam, the cylinder block and a piston during the rotation and also the movement of the fluid set in motion by the part. rotating (cylinder block or cam) and coming into contact with the fixed part (cam or cylinder block), the fluid pressures around the axial periphery of the biocylinder vary locally depending on the position of the pistons, the distance between the cylinder block and the cam (recesses and peaks of the cam lobes) and the direction of rotation. By against the axial end of the cylinder block, the pressure of the fluid does not vary or virtually no. Thus, during a complete rotation, for each scanning hole, there are several situations in which a pressure difference between two openings exists and generates a flow of fluid in this hole. These pressure variations can lead to an opening of the same hole, an alternation of overpressure and depressions relative to another opening of the hole, and therefore to inversions of the fluid flow direction in the scanning hole.

Advantageously, the cylinder block has at least one series of two sweep holes comprising a first sweeping hole having at least a first opening located on the axial end of the cylinder block located on the distributor side and a second opening located on the axial periphery of the cylinder block opposite to the axis of rotation and a second sweeping hole having at least a first opening on the axial periphery of the cylinder block opposite to the axis of rotation and a second opening on the end axial cylinder block opposite the distributor.

In this case, from one of the axial ends of the cylinder block, the sweeping fluid flows in the first sweep hole to emerge on the axial periphery of the cylinder block opposite to the axis of rotation and, from from this zone of the motor, circulates in the second sweeping hole to emerge on the other axial end of the cylinder block. This configuration is particularly suitable in the case where the cylinder block comprises two rows of cylinders arranged one after the other in the axial direction, the cylinders of one row being arranged in staggered rows with respect to those of the other row. .

Advantageously, the circulation of the fluid in the sweeping holes is favored by the addition of an additional fluid introduced into the housing, originating for example from an exchange or swaging valve.

According to another embodiment, the cylinder block has blind sweeping holes, which are formed between consecutive cylinders, and which are open on the axial periphery of the cylinder block opposite to the axis of rotation, each sweeping hole extending at least in part at least in the vicinity of a radial plane of the cylinder block in which is measured the diameter of a cylinder adjacent to the hole in question and in the radial space of said cylinder, so that fluid contained in the casing can circulate in the scanning hole in the vicinity of said cylinder to promote the cooling of the wall of the latter in a zone passing through said radial plane, at least one blind sweep hole situated in the vicinity of a cylinder being asymmetrical by relative to the radial plane in which the diameter of the cylinder is measured.

This dissymmetry allows during the relative rotation of the cylinder block and the cam to create pressure variations generating a swirling effect, and thus to promote the circulation of fluid in the hole, although it is one-eyed.

• la figure 1 est une coupe axiale d'un moteur hydraulique illustrant un premier mode de réalisation de l'invention ;
• la figure 2 est une coupe radiale dans le plan II-II de la figure 1 ;
• la figure 3 est une vue partielle en perspective du bloc-cylindres, selon une variante du premier mode de réalisation ;
• la figure 4 est une vue partielle en coupe dans un plan correspondant au plan II-II de la figure 1, pour un autre mode de réalisation ;
• les figures 5 et 6 sont des coupes, dans un plan correspondant au plan V-V de la figure 4, pour deux variantes d'un autre mode de réalisation ;
• la figure 7 est une coupe axiale partielle d'un moteur hydraulique selon un autre mode de réalisation ;
• la figure 8 est une coupe dans le plan VIII-VIII de la figure 7, sur laquelle le plan VII-VII de la coupe de la figure 7 est également indiqué ;
• la figure 9 est une vue en coupe axiale d'un moteur hydraulique selon un autre mode de réalisation ;
• la figure 10 est une vue partielle en coupe axiale illustrant une variante utilisable en particulier pour un bloc-cylindres ayant plusieurs rangées de cylindres ;
• la figure 11 est une vue en coupe dans le plan XI-XI de la figure 10;
• la figure 12 est une vue partielle en coupe axiale pour une autre variante ; et
• la figure 13 est une vue en coupe axiale pour encore une autre variante.

The invention will be better understood and its advantages will appear better on reading the detailed description which follows, of embodiments shown by way of non-limiting examples. The description refers to the accompanying drawings in which:

• the figure 1 is an axial section of a hydraulic motor illustrating a first embodiment of the invention;
• the figure 2 is a radial section in plane II-II of the figure 1 ;
• the figure 3 is a partial perspective view of the cylinder block, according to a variant of the first embodiment;
• the figure 4 is a partial sectional view in a plane corresponding to plane II-II of the figure 1 for another embodiment;
• the Figures 5 and 6 are cuts, in a plane corresponding to the VV plane of the figure 4 for two variants of another embodiment;
• the figure 7 is a partial axial section of a hydraulic motor according to another embodiment;
• the figure 8 is a section in the VIII-VIII plane of the figure 7 , on which plan VII-VII of the section of the figure 7 is also indicated;
• the figure 9 is an axial sectional view of a hydraulic motor according to another embodiment;
• the figure 10 is a partial view in axial section illustrating an alternative usable in particular for a cylinder block having several rows of cylinders;
• the figure 11 is a sectional view in the XI-XI plane of the figure 10 ;
• the figure 12 is a partial view in axial section for another variant; and
• the figure 13 is an axial sectional view for yet another variant.

The hydraulic motor shown on the figure 1 includes a three part housing, 1A, 1B and 1C. A cylinder block 10 comprising a plurality of cylinders 12 in which pistons 14 are slidably mounted is disposed in this housing. It is a piston engine radial, the cylinders being oriented radially relative to the axis A of relative rotation between the cylinder block and the housing.

In this case, the housing is fixed while the cylinder block is rotating and drives in its rotation an output shaft 16 which is secured to it by splines 17. This rotation is supported relative to the housing by bearings 18. In the casing is also arranged a fluid distributor 20 which is fixed in rotation relative to the casing by being secured to it by a system with pins and notches 22. The dispenser comprises distribution ducts 24 and 26 which are respectively connected to mains C1 and C2 for supplying and exhausting fluid.

During the relative rotation of the cylinder block and the distributor, these distribution ducts are alternately placed in communication with roll ducts 28 to push the pistons against the cam 30 or allow them to retract into their cylinders. This cam 30 is formed on the inner periphery of the part 1B of the housing part and, as seen on the figure 2 it has a wavy shape.

In this case, the distribution is of radial type since the distribution ducts 24, 26 open on a radial face 32 of the distributor 20 which is perpendicular to the axis of rotation A, and which bears against a radial face 34 of the cylinder block 10.

Of course, the invention applies to radial piston engines in which the cam is rotating while the cylinder block is stationary, and also to radial piston engines in which the distribution is of the axial type and operates by axial faces facing the cylinder block and the distributor partially engaged in the latter.

As we see better on the figure 2 , the ends of the pistons remote from the axis of rotation A carry rollers 36 which roll against the cam during the relative rotation of the cylinder block and the latter.

It is easy to understand that during the sliding of the pistons in their respective cylinders, friction is generated at the contact zones between the cylindrical surfaces in contact with the pistons and the cylinders. In particular, considering that the relative rotation of the cylinder block of the cam is in the direction R1 or R2 indicated on the figure 2 , and because of the reaction forces between the pistons and the cam, these pistons may tend to tilt slightly relative to a plane comprising their respective axes of sliding AP and the axis A of rotation and to be deformed. As a result, the greatest frictional forces affect the zones Z1 and Z2 indicated on the figure 2 these zones being located, for each piston, in the vicinity of the radial plane PR, perpendicular to the axis A and in which the diameter of the cylinder in which the piston slides can be measured. This radial plane PR corresponds, for the engine of the figure 1 , in plane II-II in which the section of the figure 2 is realized.

According to the invention, the motor has scanning holes 40, which are formed between two consecutive cylinders 12.

According to the first embodiment of the invention shown in Figures 1 to 3 these scanning holes 40 are open on the outer axial periphery 10A of the cylinder block, (opposite to the axis of rotation A). According to a first variant, corresponding to the radial section 41A shown in solid line, it concerns blind holes which pass through the radial plane PR mentioned above and extend, from the face 10A, to a depth sufficient to achieve neighborhood Z1 and Z2 areas mentioned above.

In this case, the blind hole is asymmetrical with respect to the radial plane PR in which the diameter of an adjacent cylinder is measured in order to promote the circulation of fluid in the blind hole, by a vortex effect at its inlet.

In the same spirit, the section of the blind hole is advantageously oblong.

We see on the figure 1 that the radial portion 41A of the hole 40 is connected to an axial portion 41B (shown in broken lines) at its end located near the zones Z1 and Z2. Indeed, according to a second variant, the holes 40 are also open on the axial end 10B or 10C of the cylinder block. They then advantageously have a L-shaped shape, with the radial section 41A and the axial section 41B. They could have a T-shape by being open on both axial ends of the cylinder block. It is possible to provide that the radial sections 41A of the holes 40 are centered on the radial plane PR. However, to facilitate the flow of fluid in these holes, these sections are advantageously asymmetrical with respect to this radial plane PR, as shown in FIG. figure 3 . This allows to favor, by a swirl effect at the openings 40A of the holes 40, the circulation of fluid in the latter. On the figure 3 the openings 40A of the radial sections 41A are oblong, while the openings 40B of the radial sections 41B are circular. They could also be oblong.

On the figure 3 , the openings 40B are shown in phantom to show that they may or may not exist, depending on whether the holes 40 are blind or, conversely, open on the faces 10A and 10B of the cylinder block.

As indicated above, the fluid pressures around the axial periphery of the cylinder block vary during the relative rotation of the cylinder block and the cam. For example, if the engine of the figure 2 is of the type with rotating cylinder block and with fixed cam, and considering the sweeping hole 40 located in front of the piston at the upper part of the figure 2 whose axis AP is indicated, it is found that the volume v1 of fluid downstream of this hole 40 decreases during the rotation of the cylinder block in the direction R1 so that the pressure increases locally in front of the piston, then that at the same time the volume v2 upstream of this hole 40 increases so that the pressure drops in this upstream zone. The pressure at the axial ends of the cylinder block remain unchanged or substantially unchanged.

We now describe the figure 4 , which shows a scanning hole 50 formed between two consecutive cylinders 12A and 12B, and comprising two openings, respectively 50A and 50B, respectively located in the vicinity of the cylinders 12A and 12B. More specifically, if it is considered that the cam 30 is fixed while the cylinder block rotates relative to it in the direction of rotation R1, the opening 50A of the duct 50 is behind the cylinder 12A in an area whose volume v2 is being increased, while the opening 50B is in front of the cylinder 12B in this direction of rotation, in an area whose volume v1 is being reduced.

Insofar as the ends of the pistons 14, in particular their rollers 36, protrude beyond the outer axial periphery 10A of the cylinder block while being in contact with the cam, these pistons tend to push the fluid present in front of them. between the cylinder block and the cam during rotation of the cylinder block. As a result, the opening 50B is in an area in which fluid is pushed by the piston 14 located in the cylinder 12B and is therefore in slight overpressure, while the opening 50A which is at the rear of the cylinder 12A is in an area where the fluid is in slight relative depression. This promotes the flow of fluid in the scan hole 50, the fluid entering through the opening 50B and out through the opening 50A.

In the example shown on the figure 4 , the scan hole 50 is formed of two rectilinear sections 51 and 52 which move towards each other, as they approach the axis of rotation A, until they intersect with each other. connect these two sections. Thus, the hole 50 can be made by two rectilinear machining inclined differently. This sweeping hole thus having generally a V shape can be closed at the tip of the V. Alternatively, the sections 51 and 52 can at this point communicate with a section of duct 54 directed substantially axially, as shown in broken lines on the figure 4 . To promote the circulation of the fluid, this section of duct 54 can be open on at least one of the axial ends 10B, 10C of the cylinder block.

On the figure 5 , the sweeping holes 60 formed between two consecutive cylinders 12 have two openings, 60A and 60B, respectively located on each of the two axial ends 10B and 10C of the cylinder block.

In the example shown on the figure 5 , to promote the flow of fluid in a sweeping hole 60 during the relative rotation of the cylinder block and the housing, at least one deflector is located in the vicinity of one of the openings of this hole. In the present case, two deflectors 61A and 61B are respectively located in the vicinity of the openings 60A and 60B. The orientation of these deflectors is such that when the cylinder block rotates in the direction R1 relative to the cam which is fixed, the deflector 61A promotes fluid entry through the opening 60A, while the reflector 61B promotes the fluid outlet through the opening 60B. Indeed, the deflector 61A increases the fluid pressure in the vicinity of the opening 60A, while the deflector 61B decreases it in the vicinity of the opening 60B. In the opposite direction of rotation R2, it is the opposite which occurs, the fluid entering through the opening 60B and out through the opening 60A. The deflectors may be formed by plates, respectively, 62A and 62B, respectively fixed at the axial ends 10B and 10C of the cylinder block. It may be continuous plates having, in the vicinity of each opening, a locally rectified portion after cutting, or instead of a plate for each deflector.

In the example of the figure 5 , the scanning holes 60 are directed substantially parallel to the axis of rotation A. On the figure 6 , the scanning hole 60 'also crosses the cylinder block from one side to the other by having two openings, respectively 60'A and 60'B, respectively located at the two axial ends 10B and 10C of the latter. However, this hole is inclined relative to the axis A at an inclination angle α which is preferably of the order of 3 ° to 45 °, depending on the available space. The shape shown for the sweep hole 60 'of the figure 6 can be adopted for all sweep holes or for at least some of them. However, the scanning holes or at least some of them may consist of several sections of different inclinations, in which case the section whose inclination is the highest relative to the axis A is preferably located at inlet of the hole, that is to say in the vicinity of one end, 10B and / or 10C, of the cylinder block. As is the case for hole 60 "of the figure 6 , the scanning holes or some of them may even have a continuously variable inclination, the parts near the ends 10B and 10C of the cylinder block being the most inclined relative to the axis A, while the central portion may have a low inclination, or zero or substantially zero, with respect to this axis. These forms can be obtained during the production of the cylinder block by foundry.

In general, the inclination of the sweeping holes which has just been mentioned favors the entry of fluid into these holes. Thus, with regard to the hole 60 ', if the cylinder block rotates in the direction R1, the opening 60'A located on the end 10B of the cylinder block is located forward, in the direction of rotation, of the PB projection of the opening 60'B of the same sweeping hole located on the other axial end 10C, this projection being carried out parallel to the axis of rotation A. This inclination promotes the entry of fluid through the opening 60 ' To which is located in front and is in slight overpressure, and the exit by the other opening. Of course, during the rotation in opposite direction R2, it is this time the opening 60'B which is located forward, and the fluid inlet is favored by this opening.

To further promote the flow of fluid in the scan hole 60 ', the edges of the openings 60'A and 60'B can form integrated deflectors 61'A, 61'B made by local inflections of the inclination of the hole 60 'in the vicinity of these openings. These inflections are such that they further accentuate the fact that, in the direction of rotation R1, the opening 60'A is in front of the opening 60'B and that conversely, in the direction of rotation R2, the opening 60'B is in front of the opening 60'A. The steep inclination of the hole 60 "in the vicinity of the ends 10B and 10C of the cylinder block also forms such integrated deflectors.

According to an advantageous variant, at least one scanning hole comprises at least one opening which is situated on the external axial periphery 10A of the cylinder block, and an opening located on an axial end 10B / 10C of the cylinder block. A first possibility for this variant has been described with reference to Figures 1 to 3 .. It is also possible, in the same spirit, to modify the embodiment of the Figures 5 and 6 to add to one or more holes at least one section extending substantially radially, and connect the holes 60 or 60 'to the axial periphery of the cylinder block.

The figure 7 shows an exemplary embodiment for holes opening on different sides of the cylinder block. In this case, the hole 70 comprises a substantially axial section 71 (which can be inclined as the holes 60 'of the figure 6 ), and two substantially radial sections, respectively 72 and 73, which connect the section 71 to the outer axial periphery 10A of the cylinder block. These two sections 72 and 73 are located on either side of the radial plane PR, perpendicular to the axis of rotation A and in which is measured the diameter of the cylinders between which the hole 70 is formed. This configuration makes it possible to favor the circulation indicated by the arrows of the figure 7 , forming two opposite circulation loops. According to a loop, the fluid enters through the opening 71A of the section 71 located on the axial end 10B of the cylinder block and leaves through the opening 72A of the section 72 which is situated on the same side of the plane PR as this end 10B, while for the other loop, the fluid enters through the opening 71B of the section 71 located on the axial end side 10C of the cylinder block and leaves through the opening 73A of the section 73 located on the same side of the plane PR as this end 10C. Of course, these loops constitute the preferred currents of circulation, but it is not excluded that they partially mix. In addition, the fluid pressure varies at the apertures 72A and 73A during the relative rotation of the cylinder block and the cam, as previously discussed.

This configuration can make it possible to give the sections 72 and 73 relatively large sections because, not being located on the plane PR, they are formed in areas of the cylinder block in which two consecutive cylinders are not too close.

On the figure 8 it can be seen that the section 71 can be substantially centered on the median plane between the two consecutive cylinders 12 between which the scanning hole 70 is formed, the sections 72 and 73 also being centered on this plane of symmetry PS. However, the section 71 can be inclined and the sections 72 and 73 can be slightly offset relative to the plane PS to further promote the flow of fluid in a manner similar to that represented by the figure 4 , making for example the section 72 at the rear of the cylinder 12 which is located forward in the direction of rotation and the section 73 at the front of the cylinder which is located at the rear in the same direction of rotation. In this case, the cylinder block rotates in the direction R2 relative to the cam, and the volume v2 in which the orifice 72 opens increases, thus causing a favorable depression to the fluid outlet through the orifice 72A . On the other hand, volume v1 tends to decrease.

The figure 9 shows a variant in which the scan hole 80 also has a first opening 80A which opens on one axial end of the cylinder block, in this case the end 10B, and another opening 80B which opens on the outer axial periphery 10A of the cylinder block. This hole 80 is formed of two sections, knowing of course that it could be modified to replace the substantially radial section which ends with the opening 80B by two sections of the type of the sections 72 and 73 of the figure 8 . In the example of the figure 9 , the sweeping hole 80 is open on the axial end 10B of the cylinder block against which the distributor 20 bears, in a space E which is separated from the part 1B of the housing containing the cam 30 by an obstacle 82 favoring the fluid flow within this space through the scan hole 80. For example, the obstacle 82 may be in the form of a ring, which is attached to the housing portion 1C so that its free end opposed to this part 1C is located in the vicinity of the radial face of the cylinder block forming the end 10B, or in contact with it.

During the relative rotation of the cylinder block and the cam, the fluid contained in the space E naturally tends to escape to the outside, under the effect of the centrifugal force. The obstacle 82 prevents or limits this natural tendency, and therefore forces the fluid to pass through the scanning hole 80, this scanning hole being situated between the axis of rotation A and the obstacle 82 which is advantageously located at a distance radial axis A adjacent to that which is the axial periphery 10A of the cylinder block or near the opening 80A. The presence of the obstacle 82 causes an overpressure in the vicinity of the opening 80A of the hole 80, while the pressure is lower in the vicinity of the other opening 80B.

As indicated above, it is advantageous to provide a fluid sweeping system of the motor housing. For that, on the figure 9 , a scanning duct 38 is formed in the part 1C of the casing, so as to open into the space E. The sweeping fluid thus injected, which has been advantageously cooled by an exchange system, thus passes through the hole of sweeping 80 before irrigating the rest of the housing, to achieve the desired cooling of the cylinder block.

Of course, the embodiment of the figure 9 can know several variants, in particular the sweeping hole can also be open on the end 10C of the cylinder block opposite the end 10B. Insofar as the fluid is naturally driven by the effect of the centrifugal force, this does not prevent a significant amount of fluid escaping through the opening 80B.

We now describe the Figures 10 and 11 , which illustrate a variant in which the cylinder block has at least one series of two scanning holes used successively for the circulation of the fluid for cooling the cylinder block. More specifically, this series comprises a first scanning hole 90 having a first opening 90A located on the axial end 10B of the cylinder block 10, and two openings, respectively 90B and 90C, located on the outer axial periphery 10A of the cylinder block . Indeed, this first hole 90 comprises a first section 91 which extends between the first opening 90A and, substantially, the median radial plane PM of the cylinder block, and two substantially radial sections. respectively 92 and 93, which respectively connect the openings 90B and 90C to the first section 91.

This series comprises a second scanning hole 94 which has two first openings, 94A and 94B, respectively, which are located on the outer axial periphery 10A of the cylinder block, and a second opening 94C, which is located at the end 10C of the block -cylinders opposite to the distributor. In this case, the second hole 94 has a conformation similar to that of the first hole 90, but it is arranged inverted with respect to the median plane PM. It therefore comprises a substantially axial section 95 which opens at the opening 90C, and two substantially radial sections 96 and 97, which open respectively to the openings 94A and 94B.

With this configuration, the circulation of the sweeping fluid in the two holes 90 and 94 is effected in the manner indicated by the arrows, the fluid initially located on the side of the axial end 10B of the cylinder block entering through the opening 90A to exit through openings 90B and 90C, then entering again through openings 94A and 94B to exit through opening 94C. It should be noted that the fluid located in the casing may emerge through a leakage return duct 39 in order, in particular, to undergo a heat exchange.

As is best understood by considering the figure 11 , the embodiment of the figure 10 particularly relates to the case where the cylinder block 10 comprises two rows of cylinders arranged in two slices of the cylinder block. These two slices each extend over a portion of the length of the cylinder block, on either side of the median plane PM, or slightly intersecting on this plane. We see on the figure 11 that the first scan holes 90 are located between two consecutive cylinders 12 of the first slice C1 cylinders whose diameters are measured in the radial plane PR1, while the second scan pipe holes 94 are located between two consecutive cylinders of the second slice of cylinders C2 whose diameters are measured in the radial plane PR2. In this case, the sections 92 and 93 of the first hole 90 are located on either side of the radial plane PR1, and the sections 96 and 97 are located on either side of the radial plane PR2. Of course, this is not limiting, one could instead substantially center the second sections of the conduits on these respective radial planes PR1 and PR2. It is desirable that the sections 91 and 95 of the ducts 90 and 94 extend respectively from the axial ends 10B and 10C of the cylinder block, at least to the radial planes PR1 and PR2, respectively.

Because of their situations between two consecutive cylinders respective slices C1 and C2, the first scan holes 90 and the second scan holes 94 are angularly offset relative to each other. Indeed, the cylinders of a slice are advantageously arranged substantially staggered with respect to those of the other slice, in particular for reasons of space. Under these conditions, it is not easy to form the scanning holes so that they pass directly through the cylinder block from one side, between its two axial ends 10B and 10C. The configuration that has just been described, however, makes it possible to perform the scanning for both sets of cylinders, using the fluid leaving the scanning holes used for one of the series, to irrigate the sweeping holes used for the two sets of cylinders. other series.

As we see on the figure 10 this embodiment is compatible with that described with reference to the figure 9 , that is to say that the space E situated between the axial end 10B of the cylinder block and the part 1C of the housing, on the side of the distributor 20, is confined by an obstacle 82 which makes it possible to ensure that the fluid in the space E, in particular the flushing fluid supplied by a flushing duct 38, naturally has a tendency to escape through the flushing holes 90.

It should be noted that an obstacle 98 similar to the obstacle 82 is disposed on the opposite side of the cylinder block. This obstacle 96 may also be formed by a ring fixed to the part 1A of the housing and whose free end comes into contact with or in the immediate vicinity of the end 10C of the cylinder block. This makes it possible to prevent the fluid that has emerged through the orifices 90B and 90C from the first scanning holes 90 being brought directly towards the leakage return duct 39 without first passing through the second scanning holes 94.

The figure 12 still shows a variant, wherein at least one scanning hole 100 located between two consecutive cylinders is open towards an axial end of the cylinder block in a space, which is supplied with sweeping fluid and which is delimited by at least one obstacle favoring the flow of the sweeping fluid outside this space through the sweeping hole. Specifically, the scan hole 100 has an opening 100A which is located in an area of the cylinder block adjacent to the axis of rotation A and the distributor 20.

This opening is in this case located in the immediate vicinity of the axial end 10B of the cylinder block. Indeed, in some cases, it is advantageous to take advantage of the central space 27 of the distributor to supply the casing of the fluidizer for sweeping by a valve V sweeping or exchange. In this case, the position of the opening 100A allows it to be easily supplied with sweep fluid and the valve V provides an overpressure at the inlet 100A relative to the outlet 100B.

The obstacle which promotes the flow of the sweeping fluid outside this space 27 is formed by the contact between the distribution face 32 of the distributor and the communication face 34 of the cylinder block. In other words, the zone of the cylinder block in which the opening 100A is located is defined radically by the contact zone between the distributor and the cylinder block. In the example shown, the scanning hole 100 also opens on the outer axial periphery 1QA of the cylinder block. It can be realized by a single rectilinear section, inclined so that the opening 100A is located substantially at the junction between the internal axial periphery 10D of the cylinder block and the axial end 10B of the latter, and that the opening opposite 100B is located symmetrically or substantially symmetrically with respect to the radial plane PR of the cylinder block in which the diameters of the cylinders are measured. Of course, this conformation can be modified, for example to make the duct in the form of two sections 101 and 102 connected to one another as shown in FIG. figure 12 (the section 101 being inclined relative to the radial plane PR from the opening 100A, while the section 102 is oriented radially), and / or to provide several openings 100B located on the outer axial periphery 10A of the cylinder block, for example by being located on either side of the radial plane PR.

The figure 13 illustrates a possibility of modifying the variant of the figure 12 , in which the scanning hole 100 ', which further has a configuration similar to that of the hole 100 of the figure 12 , is further open on the axial ends 10B and 10C of the cylinder block by two openings respectively 100'C and 100'D. It should be noted in this regard that the centrifugal force to which the fluid flowing in the hole is subjected As a result, the fluid that has entered through opening 100A has a natural tendency to escape through opening 100B, while fluid also tends to enter through openings 100'C and 100'D.

This variant also has the advantage, at low rotational speed and therefore in the presence of a small centrifugal force, to promote the flow of the fluid operating as an ejector. Indeed, the kinetic energy of the exchange fluid or sweep passing in the section 101 creates an additional flow of fluid by driving the fluid from the housing to the 100'D and 100'C inputs.

Of course, it is possible to combine different variants described between them. Similarly, the holes and sections of holes of the different variants may have a circular, substantially circular, oblong, substantially oblong or any other shape that can be obtained by casting or forging, combined or not with machining, this shape being able to have a variable section to reduce the thickness of the wall between the sweeping fluid and the friction zone.

It should also be noted that the holes can be made between each group of two consecutive cylinders of a row of cylinders, but they can also be made only on only part of this row.

Claims (13)

1. A hydraulic motor having radial pistons and comprising a casing (1A, 1B, 1C), a cylinder block (10) disposed in the casing so that the casing and the cylinder block are suitable for rotating relative to each other about an axis of rotation (A) and having a plurality of cylinders (12) that extend radially relative to the axis of rotation and in which the pistons (14) are slidably mounted, a reaction cam (30) for the pistons, and a fluid distributor (20) that is constrained to rotate with the cam about the axis of rotation (A) and that is provided with distribution ducts (24, 26) suitable for connecting a feed duct or a discharge duct (C1, C2) to the cylinders (12);
   said hydraulic motor being characterized in that the cylinder block (10) is provided with sweep holes (40; 50; 60; 60'; 60"; 70; 80; 90; 94; 100; 100'), each of which is formed between two consecutive cylinders (12), and each of which opens out via at least two openings (40A, 40B; 50A, 50B; 60A, 60B; 60'A; 60'B; 71A, 71B, 72A, 73A; 80A, 80B; 90A, 90B, 90C, 94A, 94B, 94C; 100A, 100B; 100'A; 100'B, 100'C, 100'D) into two zones at different pressures of the periphery of the cylinder block (10), each sweep hole extending at least partially at least in the vicinity of a radial plane (PR) of the cylinder block containing the diameter of a cylinder (12) adjacent to the hole in question, and lying within the radial extent of said cylinder, in a manner such that fluid contained in the casing can flow in the sweep hole (40; 50; 60; 60'; 60"; 70; 80; 90, 94; 100; 100') in the vicinity of said cylinder (12) so as to facilitate cooling of the wall thereof in a zone occupying said radial plane (PR).
2. A motor according to claim 1, characterized in that at least one sweep hole (40), which sweep hole is open onto that axial periphery (10A) of the cylinder block (10) that is further from the axis of rotation (A), and is situated in the vicinity of a cylinder (12), is asymmetrical about the radial plane (PR) containing the diameter of the cylinder.
3. A motor according to claim 1 or claim 2, characterized in that at least one sweep hole (50) provided between two consecutive cylinders (12A, 12B) has two openings (50A, 50B) situated on that axial periphery (10A) of the cylinder block (10) that is further from the axis of rotation (A), in the vicinities of respective ones of said cylinders (12A, 12B).
4. A motor according to any one of claims 1 to 3, characterized in that at least one sweep hole (60; 60'; 60") provided between two consecutive cylinders has two openings situated at respective ones of the two axial ends (10B, 10C) of the cylinder block, and in that means (61A, 61B; 61'A, 61'B) are provided for making it easier for fluid to flow in the sweep hole while the cylinder block (10) and the casing (1A, 1B, 1C) are rotating relative to each other.
5. A motor according to claim 4, characterized in that the sweep hole (60'; 60") is inclined relative to the axis of rotation (A) such that, while the cylinder block is rotating in one rotation direction (R1), the opening (60A') situated on one of the axial ends (10B) of the cylinder block (10) is, in said rotation direction, situated in front of the projection (PB) of said axial end of the opening (60'B) situated on the other axial end (10C), said projection being formed parallel to the axis of rotation (A).
6. A motor according to claim 4 or claim 5, characterized in that the means for making it easier for fluid to flow in the sweep hole (60; 60'; 60") while the cylinder block (10) and the casing (1A, 1B, 1C) are rotating relative to each other comprise at least one deflector (61A, 61B; 61'A, 61'B) situated in the vicinity of one of the openings (60A, 60B; 60'A, 60'B) of said hole.
7. A motor according to any one of claims 1 to 6, characterized in that at least one sweep hole (70; 80; 90, 94; 100; 100') has at least one opening (72A, 73A; 80B; 90B, 90C; 94A, 94B; 100B) situated on that axial periphery (10A) of the cylinder block (10) that is further from the axis of rotation (A) and an opening (71A, 71B; 80A; 90A, 94C; 100A) situated on an axial end (10B, 10C) of the cylinder block (10).
8. A motor according to claim 7, characterized in that the cylinder block (10) has at least one series of two sweep holes comprising a first sweep hole (90) having at least a first opening (90A) situated on that axial end (10B) of the cylinder block (10) that is situated on the same side as the distributor (20), and a second opening (90B) situated on that axial periphery (10A) of the cylinder block that is further from the axis of rotation (A), and a second sweep hole (94) having at least a first opening (94A, 94B) situated on that axial periphery (10A) of the cylinder block that is further from the axis of rotation (A) and a second opening (94C) situated on that axial end (10C) of the cylinder block (10) that is further from the distributor.
9. A motor according to any one of claims 1 to 8, characterized in that at least one sweep hole (80; 90) is open onto an axial end (10B) of the cylinder block (10), against which end the distributor (20) is in abutment, and into a space (E) separated from the casing portion (1B) that contains the cam (30) by an obstacle (82) making it easier for the fluid to flow out of said space (E) via the sweep hole (80; 90).
10. A motor according to any one of claims 1 to 9, characterized in that at least one sweep hole (80; 90; 100; 100') is open onto an axial end (10B) of the cylinder block (10) and into a space (E; 27) that is fed with sweep fluid and that is defined by at least one obstacle (82) making it easier for the sweep fluid to flow out of said space via the sweep hole.
11. A motor according to any one of claims 1 to 10, characterized in that at least one sweep hole (100; 100') has at least one opening (100A) situated in a zone of the cylinder block (10) that is adjacent to the axis of rotation (A) and to the distributor (20), that is fed with sweep fluid, and that is defined radially by a zone of contact between the distributor (20) and the cylinder block (10).
12. A hydraulic motor having radial pistons and comprising a casing (1A, 1B, 1C), a cylinder block (10) disposed in the casing so that the casing and the cylinder block are suitable for rotating relative to each other about an axis of rotation (A) and having a plurality of cylinders (12) that extend radially relative to the axis of rotation and in which the pistons (14) are slidably mounted, a reaction cam (30) for the pistons, and a fluid distributor (20) that is constrained to rotate with the cam about the axis of rotation (A) and that is provided with distribution ducts (24, 26) suitable for connecting a feed duct or a discharge duct (C1, C2) to the cylinders (12);
    said hydraulic motor being characterized in that the cylinder block (10) is provided with blind sweep holes (40) that are formed between consecutive cylinders (12), and that are open onto that axial periphery (10A) of the cylinder block that is further from the axis of rotation (A), each sweep hole extending at least partially at least in the vicinity of a radial plane (PR) of the cylinder block containing the diameter of a cylinder (12) adjacent to the hole in question, and lying within the radial extent of said cylinder, in a manner such that fluid contained in the casing can flow in the sweep hole (40) in the vicinity of said cylinder (12) so as to facilitate cooling of the wall thereof in a zone occupying said radial plane (PR), at least one blind sweep hole (40) situated in the vicinity of a cylinder (12) being asymmetrical about the radial plane (PR) containing the diameter of the cylinder.
13. A motor according to claim 12, characterized in that the blind sweep holes (40) are oblong in cross-section.

Images