Improved multi-displacement hydraulic machine

Abstract

A radial piston hydraulic machine with a multilobe cam, 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), characterized in that the hydraulic machine comprises a first distributor (160) and a second distributor (170) adapted to achieve fluid admission and discharge in the first chambers (160) and in the second chambers (170), in which the first distributor (160) and the second distributor (170) are arranged on either side of the cylinder block (30) along the axial direction (ZZ). 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 with radial pistons and a multi-lobe cam, comprising a casing defining an internal volume in which are housed a shaft extending in an axial direction, a cylinder block comprising a plurality of housings in which pistons are mounted to slide radially relative to the axial direction, and a multi-lobe cam mounted around the cylinder block and secured to the casing, in which the shaft and the cylinder block define a first assembly, and the casing and the multi-lobe cam define a second assembly, the first assembly and the second assembly being mounted to move in rotation relative to each other in the axial direction, in which each pair formed by a piston and a housing defines between the piston and the housing a first chamber and a second separate chamber,characterized in that the hydraulic machine comprises a first distributor and a second distributor adapted to carry out an admission and a discharge of fluid into the first chambers and into the second chambers, and in that the first distributor and the second distributor are arranged on either side, of the cylinder block in the axial direction.

[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 first distributor is adapted to selectively carry out the admission and discharge of fluid into the first chambers, and the second distributor is adapted to selectively carry out the admission and discharge of fluid into the second chambers.

[0009] According to one example, the first distributor and the second distributor are dimensioned so that the force resulting from the supply of the first chambers and the second chambers respectively by the first distributor and the second distributor tends to move the cylinder block towards the first distributor.

[0010] According to one example, the first distributor is adapted to selectively carry out the admission of fluid into the first chambers and to selectively carry out the admission of fluid into the second chambers, and the second distributor is adapted to selectively carry out the discharge of fluid into the first chambers and to selectively carry out the discharge of fluid into the second chambers.

[0011] 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

[0012] According to one example, for each pair formed by a piston and a housing, the first chamber and the second chamber are superimposed according to a sliding direction of the piston in the housing.

[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, the set of first chambers define a homokinetic motor or pump, and the set of second chambers define a homokinetic motor or pump.

[0017] 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 engine, 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.

[0018] For a hydraulic pump, the homokinetic characteristic means that when the rotation 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.

[0019] According to one example, the first distributor and the second distributor are groove distributors.

[0020] According to one example, the first distributor and the second distributor are stud distributors. Brief description of the drawings

[0021] 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.

[0022] [Fig.l] [Fig.l] schematically shows a multiple displacement hydraulic machine.

[0023] [Fig.2] [Fig.2] shows a cylinder block structure of a multiple displacement hydraulic machine according to one aspect of the invention.

[0024] [Fig.3] [Fig.3] shows an example of a structure of a multiple displacement hydraulic machine according to one aspect of the invention.

[0025] [Fig.4] [Fig.4] shows another example of a multiple displacement hydraulic machine structure according to one aspect of the invention.

[0026] [Fig.5] [Fig.5] shows an example of a structure of a multiple displacement hydraulic machine according to one aspect of the invention.

[0027] Throughout the figures, the elements in common are identified by identical numerical references. Description of the embodiments

[0028] [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, 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.

[0029] Figures 2, 3 and 5 illustrate an embodiment of a multiple displacement hydraulic machine according to one aspect of the invention. The hydraulic machine may present a hydraulic motor or pump operation.

[0030] [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.

[0031] [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.

[0032] [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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] In the illustrated example, conduits are arranged in the cylinder block 30, these conduits extending from the first chambers 60 and from the second chambers 70 and emerging from a lateral surface of the cylinder block 30. The conduits are then supplied by distributors.

[0038] 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 pump considered.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.

[0039] 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. The 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.

[0040] 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.

[0041] The first chambers 60 and / or the second chambers 70 typically define 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.

[0042] The hydraulic machine typically 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. The hydraulic machine then has a structure that is described as radial.

[0043] The hydraulic machine comprises a first distributor 160 and a second distributor 170.

[0044] The cylinder block 30 thus comprises conduits opening opposite each of the first distributor 160 and the second distributor 170, making it possible to connect the first chambers 60 and the second chambers 70 to the first distributor 160 and to the second distributor 170. The conduits typically open at an interface between the cylinder block 30 and the first distributor 160 or the second distributor 170, the interface typically being between two surfaces extending radially relative to the main axis ZZ.

[0045] According to one example, the first distributor 160 is adapted to selectively carry out the admission and discharge of fluid into the first chambers 60, and the second distributor 170 is adapted to selectively carry out the admission and discharge of fluid into the second chambers 70.

[0046] Alternatively, the first distributor 160 is adapted to selectively carry out the admission of fluid into the first chambers 60 and to selectively carry out the admission of fluid into the second chambers 70, and the second distributor 170 is adapted to selectively carry out the discharge of fluid into the first chambers 60 and to selectively carry out the discharge of fluid into the second chambers 70.

[0047] In the proposed structure, the first distributor 160 and the second distributor 170 are arranged on either side of the cylinder block 30 in the direction defined by a main axis ZZ.

[0048] Such a structure with a distributor on either side of the cylinder block 30 is advantageous insofar as it makes it possible to balance the forces applied to the distributor, and therefore to reduce the load on the rolling elements compared to a structure comprising a single distributor on one side of the cylinder block 30. Thus, by balancing the forces applied on either side of the cylinder block 30, the load applied to the rolling elements forming the bearings 12 is minimized.

[0049] Optionally, the first distributor 160 and the second distributor 170 are configured so that in operation, the force resulting from the supply and discharge of pressure from the first chambers 60 and the second chambers 70 tends to move the cylinder block towards one of the first distributor 160 and the second distributor 170, for example towards the first distributor 160, or alternatively towards the second distributor 170.

[0050] Such a configuration thus makes it possible to determine in advance which element of bearing will have to support an axial load due to the thrust of the cylinder block 30 on one of the distributors, and thus allows the rolling elements to be sized appropriately. A thrust bearing of the needle thrust type, roller thrust bearing or a shoulder can in particular be integrated into the hydraulic machine.

[0051] In the example illustrated in [Fig. 3], a stop 162 is thus positioned between the cylinder block 30 and the casing 10 on the side of the cylinder block 30 comprising the second distributor 170. Such a stop 162 makes it possible in particular to take up the forces resulting from operation at full cylinder capacity, the first distributor 160 and the second distributor 170 then being configured so that the resultant of the forces tends to move the cylinder block 30 towards the second distributor 170. As a variant, two stops can be positioned on either side of the cylinder block 30.

[0052] The first distributor 160 and the second distributor 170 are typically positioned opposite the cylinder block 30 at distinct radial positions relative to the main axis ZZ. The conduits formed in the cylinder block 30 and allowing them to be selectively connected to the first chambers 60 or to the second chambers 70 therefore also open at distinct radial positions relative to the main axis ZZ.

[0053] Such a structure makes it possible in particular to simplify the internal structure of the cylinder block 30 by increasing the distance between the different conduits, and therefore making it possible to improve the mechanical strength of the cylinder block 30.

[0054] In the illustrated embodiment, it can be seen that the distributors 160 and 170 are supplied from each side of the cylinder block 30, and therefore on either side of the cam 20. This embodiment makes it possible in particular to position a displacement selection valve 80 offset or flanged on the casing 10. Such a structure makes it possible to simplify the internal structure of the hydraulic machine, and also makes it easier to modify the supply system via the displacement selection valve 80.

[0055] As a variant, all of the supply and discharge conduits of the hydraulic machine can be formed in the same portion of the casing 10, on the same side relative to the cam 20 and the cylinder block 30. Distribution conduits are then formed through the cam 20 so as to produce conduits opening on either side of the cylinder block 30 to connect the first chambers 60 and the second chambers 70 respectively to the first distributor 160 and to the second distributor 170 as described previously.

[0056] Such a variant makes it possible to simplify the connections to the hydraulic machine.

[0057] In the example illustrated, the first distributor 160 and the second distributor 170 are grooved distributors.

[0058] Alternatively, the first distributor 160 and the second distributor 170 may be plot distributors.

[0059] [Fig. 4] schematically illustrates such a variant. Only the elements that differ from [Fig. 3] described previously are indicated here. A stud distributor typically comprises a part interposed between the cylinder block 30 and the casing 10, comprising distribution orifices adapted to connect supply and delivery conduits formed in the casing 10, and conduits formed in the cylinder block 30. The interposed part may for example take the form of a ring or a disc centered relative to the main axis ZZ. In the example illustrated, the first distributor 160 and the second distributor 170 thus respectively comprise a part interposed between the distributor and the cylinder block 30, respectively 162 and 172.

[0060] 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.

[0061] 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 with radial pistons and multi-lobe cam, comprising a casing (10) defining an internal volume in which a shaft (32) extending in an axial direction (ZZ) is housed, a cylinder block (30) comprising a plurality of housings (40) in which pistons (50) are mounted to slide radially relative to the axial direction (ZZ), and a multi-lobe cam (20) mounted around the cylinder block (30) and secured to the casing (10), in which the shaft (32) and the cylinder block (30) define a first assembly, and the casing (10) and the multi-lobe cam (20) define a second assembly, the first assembly and the second assembly being mounted to move in rotation relative to each other in the axial direction (ZZ), 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 separate chamber (70),characterized in that the hydraulic machine comprises a first distributor (160) and a second distributor (170) adapted to carry out an admission and a discharge of fluid into the first chambers (160) and into the second chambers (170), and in that the first distributor (160) and the second distributor (170) are arranged on either side of the cylinder block (30) in the axial direction (ZZ).,

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. Hydraulic machine according to one of claims 1 or 2, in which the first distributor (160) is adapted to selectively carry out the admission and the discharge of fluid in the first chambers (60), the second distributor (170) is adapted to selectively carry out the admission and the discharge of fluid in the second chambers (70).

4. Hydraulic machine according to claim 3, in which the first distributor (160) and the second distributor (170) are dimensioned so that the force resulting from the supply of the first chambers (60) and second chambers (70) respectively by the first distributor (60) and the second distributor (70) tends to move the cylinder block (30) towards the first distributor (160).

5. Hydraulic machine according to one of claims 1 or 2, in which the first distributor (160) is adapted to selectively carry out the admission of fluid into the first chambers (60) and to selectively carry out the admission of fluid into the second chambers (70), the second distributor (170) is adapted to selectively carry out the discharge of fluid into the first chambers (60) and to selectively carry out the discharge of fluid into the second chambers (70).

6. Hydraulic machine according to one of claims 1 to 5, 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).

7. Hydraulic machine according to one of claims 1 to 6, 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).

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

9. Hydraulic machine according to claim 8, in which for each pair formed by a housing (40) and a piston (50), the first chamber (60) has an effective section strictly greater than the second chamber (70).

10. Hydraulic machine according to claim 8, in which for each pair formed by a housing (40) and a piston (50), the first chamber (60) has an effective section strictly smaller than the second chamber (70).

11. Hydraulic machine according to one of claims 1 to 10, in which the first distributor (160) and the second distributor (170) are groove distributors.

12. Hydraulic machine according to one of claims 1 to 10, in which the first distributor (160) and the second distributor (170) are stud distributors.

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