Improved multi-displacement hydraulic machine

Abstract

Hydraulic machine in which each pair formed by a piston (50) and a housing (40) defines between the piston (50) and the housing (40) a first chamber (60) and a second chamber (70) distinct, the cylinder block (30) and the distributor (165) each having a plurality of internal conduits defining a first set of conduits and a second set of conduits, said sets of conduits opening at the interface between the distributor (165) and the cylinder block (30) at two distinct radii with respect to the main axis (ZZ) and being adapted to supply respectively the first chambers (60) and the second chambers (70). Figure for the abbreviation: Fig. 2.

Description

Title of the invention: Improved multi-cylinder hydraulic machine Technical field

[0001] The present invention relates to a multi-cylinder hydraulic machine having an improved distribution structure. Prior art

[0002] Hydraulic machines with multiple displacements are known and commonly used. Such hydraulic machines have several displacement values ​​that can be engaged, in order to offer several operating modes. For example, hydraulic machines offering a first mode delivering high torque at low speed, and a second mode delivering reduced torque at high speed can be cited.

[0003] Such hydraulic machines offer advantageous flexibility while maintaining a reduced footprint.

[0004] A recurring difficulty in producing such hydraulic machines concerns fluid distribution. The production of such multiple cylinder capacities generally involves complex structures for the associated distributor. We can notably cite document FR2836960 which presents a structure of a multi-cylinder hydraulic motor with a specific distributor.

[0005] The present invention aims to respond at least partially to this problem. Statement of the invention

[0006] The present invention thus relates to a hydraulic machine comprising: a first assembly and a second assembly, movable in rotation relative to each other along a main axis, the first assembly comprising a casing and a multi-lobe cam, the second assembly comprising a shaft, a cylinder block, the cylinder block having a plurality of housings in which pistons slide, each piston being positioned in a housing, the hydraulic machine further comprising a distributor adapted to provide a supply and a discharge of fluid, the distributor bearing against the cylinder block along an interface extending radially relative to the main axis, characterized in that each pair formed by a piston and a housing defines between the piston and the housing a first chamber and a second separate chamber, the cylinder block and the distributor each have a plurality of conduits internals defining a first set of conduits and a second set of conduits, said sets of conduits opening at the interface between the distributor and the cylinder block along two distinct radii relative to the main axis and being adapted to supply the first chambers and the second chambers respectively.

[0007] According to one example, the shaft extends out of the housing, and is adapted to transmit or receive movement and / or rotational torque.

[0008] According to one example, the cam extends around the cylinder block relative to the main axis, and wherein the cylinder block is configured such that the pistons slide radially relative to the main axis upon relative rotation between the first set and the second set.

[0009] According to one example, the distributor is a groove distributor.

[0010] According to one example, the distributor is a stud distributor, having at least one distribution plate at the interface between the distributor and the cylinder block.

[0011] According to one example, the distributor comprises two concentric distribution plates; a first distribution plate adapted to connect the conduits of the first set of conduits, and a second distribution plate adapted to connect the conduits of the second set of conduits.

[0012] According to one example, for each pair formed by a piston and a housing, the first chamber has a cylinder capacity strictly greater than the second chamber.

[0013] According to one example, for each pair formed by a housing and a piston, the first chamber and the second chamber have different effective sections.

[0014] According to one example, for each pair formed by a housing and a piston, the first chamber has an effective section strictly greater than the second chamber.

[0015] According to one example, for each pair formed by a housing and a piston, the first chamber has an effective section strictly lower than the second chamber.

[0016] According to one example, each housing has a first portion having a first section S1, and a second portion having a second section S2, the first section S1 being strictly greater than the second section S2, the first portion extending from an external surface of the cylinder block, and the second portion extending from the first portion. The pistons are typically configured so as to define an effective section during operation, such that the effective section of the first chambers is strictly greater than the effective section of the second chambers.

[0017] According to an example, each for each pair formed by a piston and a housing, the first chamber and the second chamber are superimposed in a direction of smoothing of the piston in the housing.

[0018] According to one example, the set of first chambers define a homokinetic motor or pump, and the set of second chambers define a homokinetic motor or pump.

[0019] For a hydraulic motor, the homokinetic characteristic means that, when the fluid supply flow rate is constant, the rotational speed of the rotating part of the motor, typically the cylinder block or the cam, is substantially constant. In other words, the rotation occurs smoothly. In a homokinetic motor, the fluid balance is substantially zero, that is to say that at each instant, the quantity of fluid entering the cylinders is substantially equal to the quantity of fluid leaving the cylinders.

[0020] For a hydraulic pump, the homokinetic characteristic means that when the rotational speed of the rotating part is constant, the flow rate of fluid delivered by the pump is constant. In other words, the flow rate delivered does not present any jolts.

[0021] The present invention also relates to an assembly comprising a hydraulic machine as defined above, and a displacement change valve adapted to selectively supply pressure to the first set of conduits and / or the second set of conduits. Brief description of the drawings

[0022] The invention and its advantages will be better understood upon reading the detailed description given below of different embodiments of the invention given as non-limiting examples.

[0023] [Fig.l] [Fig.l] schematically shows a multiple displacement hydraulic machine.

[0024] [Fig.2] [Fig.2] shows a cylinder block structure of a multiple displacement hydraulic machine according to one aspect of the invention.

[0025] [Fig.3] [Fig.3] shows an example of a multiple displacement hydraulic machine structure according to one aspect of the invention.

[0026] [Fig.4] [Fig.4] shows another example of a multiple displacement hydraulic machine structure according to one aspect of the invention.

[0027] [Fig.5] [Fig.5] shows an example of a structure of a multiple displacement hydraulic machine according to one aspect of the invention.

[0028] [Fig.6] [Fig.6] shows an example of a distributor structure for a hydraulic machine according to one aspect of the invention.

[0029] Throughout the figures, the elements in common are identified by identical numerical references. Description of the embodiments

[0030] [Fig.l] is a schematic representation of a multiple displacement hydraulic machine. In the example illustrated, a hydraulic motor M is schematized as being composed of two hydraulic sub-motors Ml and M2 coupled in rotation. One and / or the other of the two hydraulic sub-motors Ml and M2 can be selectively engaged, typically by controlling the intake and discharge of each of the two hydraulic sub-motors Ml and M2. It is understood that this figure can also be transposed for a hydraulic pump composed of two hydraulic sub-pumps.

[0031] Figures 2, 3 and 5 illustrate an embodiment of a multi-displacement hydraulic machine according to one aspect of the invention. The hydraulic machine may have a hydraulic motor or pump operation.

[0032] [Fig.2] shows a partial view of a cylinder block 30 defining a housing 40 in which slides a piston 50, typically adapted to be held in contact with a cam, for example a multi-lobe cam. In operation, the pistons follow the cam. Thus, the pistons perform back and forth movements in their respective housings according to the geometry of the cam, while remaining in contact with the cam.

[0033] [Fig. 3] shows a more complete view, comprising a cam 20 and a casing 10. The cam 20 is positioned so as to surround the cylinder block 30 relative to the main axis ZZ. The casing 10 and the cam 20 define an internal volume in which the cylinder block 30 is housed. The cylinder block 30 is integral with a shaft 32 mounted to rotate relative to the casing 10 by means of bearings 12. The cylinder block 30 and the shaft 32 form an assembly that is rotatable relative to the assembly formed by the cam 20 and the casing 10 by means of an axis 32 defining the main axis ZZ. The shaft 32 typically extends outside the casing 10, and is adapted to receive or transmit a movement and / or a rotational torque depending on whether the hydraulic machine has a hydraulic pump or hydraulic motor operation. In the example shown, the cam surrounds the cylinder block.Alternatively, the adapter 100 may have a radial architecture with an internal cam mounted to move in rotation relative to the cylinder block 30 and to a casing 10, the cylinder block 30 then typically being integral in rotation with the casing 10.

[0034] [Fig. 5] shows an example of a radial machine structure. This figure shows a cylinder block 30 surrounded by a multi-lobe cam 20. In this example, the cylinder block 30 comprises 9 housings and the cam defines 6 lobes.

[0035] In the illustrated example, the hydraulic machine has a radial structure. By radial structure, it is meant that the pistons 50 and the housings 40 are arranged so as to define a movement of the pistons 50 in a radial direction relative to the main axis ZZ. In the remainder of the description, the radial direction refers to a radial direction relative to the main axis ZZ.

[0036] In the structure proposed by the present invention, each pair formed by a piston 50 and a housing 40 defines a first chamber 60 and a second chamber 70 which are distinct, isolated from each other by means of sealing elements.

[0037] The first chamber 60 and the second chamber 70 are typically superimposed according to the sliding direction of the piston 50 in the housing 40, here the radial direction relative to the main axis ZZ.

[0038] In the example illustrated, the housing 40 has two distinct portions; a first portion 41 having a first section S1, and a second portion 42 having a second section S2, the first section S1 being strictly greater than the second section S2, the first portion extending from an external surface of the cylinder block 30 and opening opposite the cam, and the second portion 42 extending from the first portion 41 so as to form the bottom of the housing 40. The second portion 42 is thus typically blind in the sliding direction of the pistons 50.

[0039] The piston 50 also has a first portion 51 and a second portion 52 adapted to slide respectively in the first portion 41 and the second portion 42 of the housing 40 while ensuring the sealing of the first chamber 60 and the second chamber 70.

[0040] Such a structure makes it possible to define in a single cylinder block and on a single row of pistons coming into contact with the same cam, two distinct hydraulic machines via the first chambers 60 and the second chambers 70. The two hydraulic machines thus formed may have identical or distinct cylinder capacities, which are designated respectively by C1 and C2. The cylinder capacity is defined as being the product of the effective section of a chamber considered by the stroke of the piston, the effective section of a piston being the total surface area of ​​the piston which participates in creating a force tending to move the piston in the desired direction. A distinction is made between the cylinder capacity for a given piston and the cylinder capacity for a motor or a pump, which is equal to the sum of the cylinder capacity of the pistons for the motor or the pump considered. The cylinder capacity C1 of the first chambers 60 is thus defined by the stroke of the piston multiplied by the effective section of the first chambers 60.The cylinder capacity C2 of the second chambers 70 is thus defined by the stroke of the piston multiplied by the effective section of the second chambers 70. The proposed structure thus makes it possible to produce a structure allowing multi-cylinder operation with a limited number of pistons and lobes and with the same row of pistons, which is advantageous in terms of compactness and therefore integration.

[0041] For each pair formed by a housing and a piston, the first chamber 60 and the second chamber 70 thus typically have distinct effective sections. first chamber 60 can thus have an effective section strictly greater than the second chamber 70, or conversely, the first chamber 60 can thus have an effective section strictly less than the second chamber 70.

[0042] The cylinder capacity of the hydraulic machine can thus be modulated by supplying or not the first chambers 60 and / or the second chambers 70. The hydraulic machine can thus have a cylinder capacity equal to C1, to C2, or to C1+C2.

[0043] Each of the two hydraulic machines thus formed typically defines a homokinetic hydraulic machine; for a constant rotational speed of the cylinder block 30 relative to the cam 20, the first chambers 60 and / or the second chambers 70 deliver a constant or substantially constant flow rate, in contrast in particular to an oscillating linear actuator which delivers pressure by pulsations.

[0044] Conduits 62 and 64 are arranged in the cylinder block 30, these conduits extending respectively from the first chambers 60 and from the second chambers 70 and emerging from a lateral surface of the cylinder block 30. The conduits 62 and 64 are then supplied by a distributor 165.

[0045] The cylinder block 30 thus comprises conduits 62 and 72 opening opposite the distributor 165, making it possible to connect the first chambers 60 and the second chambers 70 to the distributor 165. The conduits 62 and 72 typically open at an interface between the cylinder block 30 and the distributor 165, the interface typically being between two surfaces extending radially relative to the main axis ZZ.

[0046] the ducts 62 and 72 formed in the cylinder block 30 open at distinct positions relative to the main axis ZZ; for example the ducts connected to the first chambers 60 are centered on a circle of radius RI relative to the main axis ZZ, and the ducts connected to the second chambers 70 are centered on a circle of radius R2 relative to the main axis ZZ with RI different from R2. In the example illustrated, RI is strictly greater than R2, the first chambers 60 being located radially to the outside relative to the second chambers 70. The distributor 165 has internal ducts adapted to open at the interface between the distributor 165 and the cylinder block, opposite the ducts 62 and 72, and thus allow supply and discharge of the first chambers 60 and second chambers 70.It is thus possible to define a first set of conduits for supplying the first chambers 60, comprising conduits internal to the distributor 165 and the conduit 62 internal to the cylinder block. It is also possible to define a second set of conduits for supplying the second chambers 70, comprising conduits internal to the distributor 165 and the conduit 72 internal to the cylinder block.

[0047] [Fig. 6] illustrates an example of such a distributor 165. This figure presents a view of the face of the distributor 165 coming to the interface with the cylinder block 30. We designate by the reference 160 the internal conduits of the distributor 165 adapted to come opposite the conduits 62 and 64 of the cylinder block 30 extending from the first chambers 60, and by the reference 170 the internal conduits of the distributor 165 adapted to come opposite the conduits 72 and 74 of the cylinder block 30 extending from the second chambers 70. It can be seen that the internal conduits 160 are arranged according to a circle of radius DI relative to the main axis ZZ, and that the internal conduits 170 are arranged according to a circle of radius D2 relative to the main axis ZZ, such that DI > D2.

[0048] Such a structure makes it possible to simplify the connection of the chambers to the distributor, and thus to simplify the general structure of the distributor 165 compared to known structures.

[0049] In the example illustrated in [Fig. 3], the distributor 165 is a grooved distributor. It comprises in particular a distribution cover 167 provided with a displacement change valve 169, adapted to selectively connect the different conduits 62 and 72 to an inlet or a discharge of fluid formed in the casing or in the distribution cover 167.

[0050] By way of example, considering an engine operation, the displacement change valve 169 can in particular make it possible to connect the first 60 and / or the second chambers 70 to the intake in order to obtain operation with a displacement equal to C1, C2 or C1+C2. By way of example, in the case where only the second chambers 70 are supplied, the first chambers 60 can be connected to a reservoir R, or be connected to each other and isolated from the intake and the discharge. The operation of a displacement selector is well known and will therefore not be detailed here.

[0051] The cylinder change valve 169 can be integrated into the distribution cover 167 or into the casing 10, or even be attached to the casing 10.

[0052] Alternatively, the distributor 165 may be a stud distributor.

[0053] [Fig.4] schematically illustrates such a variant. Here only the elements distinguishing themselves from the [Fig.3] described previously. A stud distributor typically comprises a distribution part or plate interposed between the cylinder block 30 and the casing 10, comprising distribution orifices adapted to put into communication supply and discharge conduits formed in the casing 10, and conduits formed in the cylinder block 30. The interposed distribution plate may for example take the form of a ring or a disc centered relative to the main axis ZZ. In the example illustrated, two distribution plates 162 and 172 of annular shape are interposed between the distributor and the cylinder block 30, respectively opposite the conduits 62 and 72.

[0054] Alternatively, the distributor may have a single distribution plate, ty annular-shaped stitching, having holes formed opposite the conduits 62 and 72.

[0055] Although the present invention has been described with reference to specific exemplary embodiments, it is obvious that modifications and changes may be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various illustrated / mentioned embodiments may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

[0056] It is also obvious that all the characteristics described with reference to a method are transposable, alone or in combination, to a device, and conversely, all the characteristics described with reference to a device are transposable, alone or in combination, to a method.

Claims

Claims

1. Hydraulic machine comprising: a first assembly and a second assembly, movable in rotation relative to each other along a main axis (ZZ), the first assembly comprising a casing (10) and a multi-lobe cam (20), the second assembly comprising a shaft (32), a cylinder block (30), the cylinder block (30) having a plurality of housings (40) in which pistons (50) slide, each piston (50) being positioned in a housing (40), the hydraulic machine further comprising a distributor (165) adapted to supply and discharge fluid, the distributor (165) bearing against the cylinder block (30) along an interface extending radially relative to the main axis (ZZ), characterized in that each pair formed by a piston (50) and a housing (40) defines between the piston (50) and the housing (40) a first chamber (60) and a second chamber (70) which are distinct,the cylinder block (30) and the distributor (165) each have a plurality of internal conduits defining a first set of conduits and a second set of conduits, said sets of conduits opening at the interface between the distributor (165) and the cylinder block (30) along two distinct radii relative to the main axis (ZZ) and being adapted to supply the first chambers (60) and the second chambers (70) respectively.,

2. A hydraulic machine according to claim 1, wherein the shaft (32) extends out of the housing (10), and is adapted to transmit or receive rotational movement and / or torque.

3. A hydraulic machine according to claim 1 or 2, wherein the cam (20) extends around the cylinder block (30) relative to the main axis (ZZ), and wherein the cylinder block (30) is configured such that the pistons (50) slide radially relative to the main axis (ZZ) during relative rotation between the first assembly and the second assembly.

4. Hydraulic machine according to one of claims 1 to 3, in which the distributor (165) is a groove distributor.

5. Hydraulic machine according to one of claims 1 to 3, in which the distributor (165) is a stud distributor, having at least one distribution plate (162, 172) at the interface between the distributor (165) and the cylinder block (30).

6. Hydraulic machine according to one of claims 1 to 5, in which for each pair formed by a piston (50) and a housing (40), the first chamber (60) has a cylinder capacity strictly greater than the second chamber (70).

7. Hydraulic machine according to one of claims 1 to 6, in which each housing (40) has a first portion (41) having a first section S1, and a second portion (42) having a second section S2, the first section S1 being strictly greater than the second section S2, the first portion (41) extending from an external surface of the cylinder block (30), and the second portion (42) extending from the first portion (41).

8. Hydraulic machine according to one of claims 1 to 7, in which for each pair formed by piston (50) and a housing (40), the first chamber (60) and the second chamber (70) are superimposed in a sliding direction of the piston (50) in the housing (40).

9. An assembly comprising a hydraulic machine according to one of the preceding claims and a displacement change valve (169) adapted to selectively supply pressure to the first set of conduits and / or the second set of conduits.

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