Hydraulic machine comprising cylinder with housing

Abstract

A hydraulic machine includes a cylinder (12) having housings (14), each housing including a head region (66) and a foot region (68), the foot region being delimited by a main face (70) and having a cavity (72) extending from the main face (70) in a direction from a bottom (48) of the housing to the head region and not blocking rotation of the piston, and a piston (16) in the housing.

Description

Technical Field

[0001] The present invention relates to the field of hydraulic presses, in particular to a cylinder body of a hydraulic press. Background Art

[0002] A rotary hydraulic machine typically includes a cylinder having a housing in which slidably movable pistons are received. These pistons either move a fluid or are moved by the fluid, depending on whether the machine operates as a pump or a motor.

[0003] It is known to give the piston a stepped shape for reasons of compactness (compared to a profiled piston with a single cross-section). In practice, the stepped piston allows the piston axes to be brought closer together, and the housing to be brought closer to the axis of rotation of the cylinder, while providing the same effective displacement. However, the known fluid supply / discharge ducts supply the housing from below, in a direction radial to the axis of rotation, which still results in a loss of radial compactness.

[0004] Thus, it is envisaged that the housing is not supplied from below but from the side, the duct no longer extends along a radial axis, but along an axis parallel to the axis of rotation. However, the duct is largely blocked by the piston when it occupies its position closest to the bottom of the housing (this position is usually called "bottom dead center" by those skilled in the art).

[0005] Another design involves a housing that is supplied laterally at the piston foot, while also providing a recess along the piston axis in the non-functional area of ​​the piston foot. This arrangement allows fluid to reach the lower portion of the housing, supplying the entire chamber. However, fluid reaching the lower portion of the housing is still interrupted when filling the housing in motor mode, resulting in pressure loss. The same problem arises when fluid is expelled from the housing through the piston in pump mode.

[0006] One object of the present invention is to facilitate the filling of a housing with a fluid from a supply conduit, and the exit of this fluid from the housing, without compromising the compactness of the assembly. Summary of the Invention

[0007] For this purpose, a hydraulic press is provided, comprising:

[0008] - a cylinder having a housing, and

[0009] - a piston in a housing,

[0010] Each shell includes a head area and a foot area,

[0011] The foot area is bounded by a main surface and has a cavity:

[0012] - cut into the main surface,

[0013] - extends in a direction from the base of the housing to the head region, and

[0014] -Does not prevent the piston from rotating.

[0015] The cavity thus allows the fluid passage cross-section to be expanded in an area that would otherwise have a significantly reduced cross-section. This reduces interruptions in the fluid flow. The cavity thus facilitates both filling the housing with fluid and draining it out of the housing. The fluid reaches the housing without prior compression, allowing the piston to begin its upward movement. The present invention allows for reduced pressure losses. Reducing pressure losses thus allows for a lower fluid temperature (for the same force and the same speed). This temperature reduction allows for less restriction on the machine's rotational speed. The present invention also allows for a reduction in shear forces on the fluid, preventing premature aging.

[0016] It can be provided that the cavity opens into the head region.

[0017] The cavity may be arranged to extend fully from the axis of the housing a distance which is less than a greater distance between the head region and the axis.

[0018] The cavity does not necessarily extend into the extension of the surface of the head region of the housing.

[0019] The cavity may be arranged to extend completely a distance from a mid-plane of the housing perpendicular to the axis of rotation of the machine.

[0020] The cavity thus extends beyond the functional area, which comprises the area of ​​the piston and the area of ​​the housing, which areas support one another in a circumferential direction relative to the axis of rotation of the machine. The position of the cavity thus preserves this area.

[0021] The cavity may be configured in a cylindrical shape.

[0022] The cylinder may have, for example, a circular, polygonal, rectangular or elliptical cross-section.

[0023] The cavity may be arranged to have an axis parallel to the axis of the housing.

[0024] The cavity may be arranged to have an axis perpendicular to the axis of the housing.

[0025] The cavity may be arranged to have an axis that is inclined relative to an axis of the housing.

[0026] A supply conduit may be provided leading to the cavity.

[0027] This arrangement further helps the fluid to enter and leave the housing more easily. In addition, this arrangement reduces the length of the supply conduit. The machining time of the supply conduit is therefore also shortened, if necessary, compensating for the additional time required for machining the cavity.

[0028] A duct for supplying the housing can be provided extending relative to the axis of the housing at the level of the foot region.

[0029] This is therefore an arrangement in which the duct does not open into a volume situated below the foot region, but is situated directly at the level of the foot region.

[0030] The piston may be configured to include a foot having a primary face and a secondary face cutting into the primary face of the piston foot, the cavity having a dimension along a direction perpendicular to the axis of the housing that is smaller than a dimension of the secondary face along the direction perpendicular to the axis.

[0031] The piston may be arranged to include a foot having a piston foot cavity opening to two opposite sides of the foot at two respective ends of the piston foot cavity opposite to each other along a main axis of the piston foot cavity.

[0032] Thus, the piston foot cavity allows passage of fluid through or beneath the piston foot. This reduces interruptions in the flow of fluid to the supply housing as the fluid leaves the supply conduit. This allows pressure losses to be reduced.

[0033] The housing may be configured to further have a groove configured to prevent rotation of the piston.

[0034] Since the piston carries a pin that prevents the piston from rotating, the cavity may be provided with a size that is insufficient to accommodate the pin.

[0035] This provides a way to prevent errors when installing the piston in the housing.

[0036] The housing may be configured to have no plane of symmetry.

[0037] A cylinder block for a hydraulic machine according to the present invention may also be provided.

[0038] The cylinder has a housing with a head area and a foot area,

[0039] The foot area is bounded by the main surface and has:

[0040] - a cavity cut into the main face and extending in a direction from the bottom of the shell to the head area, and

[0041] A groove cut into the main face and extending completely a distance from the cavity and in the direction of the axis of the housing.

[0042] The present invention also provides a method for manufacturing a cylinder according to the present invention, wherein:

[0043] -The cavity is made by removing material;

[0044] - the cavity and the slot are made by removing material using the same tool; and / or

[0045] -The cylinder body having the cavity is manufactured by casting.

[0046] In particular, when the cylinder is produced by casting, the recess may be obtained by a core (possibly sand) before casting.

[0047] In another embodiment, the cylinder having the cavity is manufactured by additive manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] An embodiment of the present invention will now be presented by way of non-limiting example with the support of the accompanying drawings, in which:

[0049] - Figure 1 is an axial cross-sectional view of a machine according to a first embodiment of the present invention;

[0050] - Figures 2 to 5 yes Figure 1 a view of one of the casings of the machine;

[0051] - Figure 6 and Figure 7 are similar views showing the two positions of the piston in the housing of the cylinder;

[0052] - Figure 8 is a view similar to the previous view showing the passage of fluid in the housing;

[0053] - Figure 9 It is a perspective view of the cylinder;

[0054] - Figure 10 and Figure 11 It is a schematic diagram of the functional areas of the cylinder and piston;

[0055] - Figure 12 is a sectional view of a housing of a machine of a second embodiment;

[0056] - Figures 13 to 16 is a similar view showing a third embodiment;

[0057] - Figure 17 is a perspective view of a piston of a machine according to a fourth embodiment;

[0058] - Figure 18 and Figure 19 are views showing two positions of the piston in its housing;

[0059] - Figure 20 is a cross-sectional view of the piston and housing, and

[0060] - Figure 21 The passage of the fluid in the housing is shown. DETAILED DESCRIPTION

[0061] First embodiment

[0062] Figures 1 to 11 A rotary hydraulic machine 2 according to a first embodiment of the present invention is shown.

[0063] Machine 2 comprises a fixed part and a rotating part, the latter being movably mounted for rotation relative to the fixed part about an axis of rotation XX. The machine thus comprises a housing 4 and a central shaft 6, which is movably mounted for rotation relative to the housing by means of a bearing 8. A cam 10 is rigidly fixed to the housing. A cylinder 12 is rigidly fixed to the shaft 6. The cylinder has a housing 14 extending radially to the axis XX and receiving a respective piston 16, which is movably mounted for sliding movement in the housing, each piston sliding radially to the axis XX. Each piston carries a roller 18 capable of rolling on a track of the cam 10, which for this purpose has a lobe, known per se and not shown.

[0064] The machine comprises a distributor 20 connected to a high-pressure fluid circuit and a low-pressure fluid circuit. For each housing 14, the cylinder 12 comprises a fluid supply and discharge duct 22 leading to the housing. The machine is arranged so that the distributor 20 puts the supply duct 22 into communication with the high-pressure circuit sometimes and with the low-pressure circuit sometimes, depending on the angular position of the cylinder 12 (and therefore the shaft 6) relative to the housing 4.

[0065] When housing 14 is in turn supplied with high-pressure fluid, this pressure is communicated to the associated piston 16, which slides in its housing and, through the rolling of roller 18 against multi-lobe cam 10, causes the rotating part to rotate. The machine then operates as a motor, rotating a load fixed to a shaft or housing. Conversely, when the rotating part rotates relative to the fixed part, cam 10 in turn causes the sliding of piston 16, which discharges fluid from its housing 14 into the high-pressure circuit. The machine then operates as a pump.

[0066] The present invention is applicable to machines having configurations other than this.

[0067] As especially in Figures 6 to 8 As shown in FIG, each piston 16 comprises a head 26 and a foot or tail 28. The piston has a main axis PP extending from the head to the foot and oriented here in a direction radial to the axis XX. The piston 16 in this case has a general shape that is rotationally symmetrical about this axis, but this is not mandatory.

[0068] In this example, the foot 28 and the head 26 each have a substantially cylindrical shape, with a circular cross-section in a plane perpendicular to the axis PP.

[0069] As especially in Figure 4 As shown in FIG, foot 28 has a larger dimension Dp along a direction perpendicular to axis PP. Similarly, head 26 has a larger dimension Dt along this direction. In this case, these larger dimensions are diameters. The maximum diameter Dp of foot 28 is therefore smaller than the maximum diameter Dt of head 26. The head occupies a larger volume than the foot.

[0070] This is thus a stepped piston 16 which is itself coaxially housed in a stepped housing 14 of complementary shape, as in Figures 6 to 8 This shape offers advantages in terms of compactness compared to pistons with a generally cylindrical shape. In fact, thanks to the stepped pistons, the piston axes PP can be brought closer together while maintaining the same effective displacement. The angle between the axes PP of two adjacent pistons is thus reduced compared to the angle achieved with non-stepped pistons (i.e., pistons having the same diameter of the head 26 over their entire length). This shape also brings the housing 14 closer to the axis of rotation XX of the cylinder 12.

[0071] The head 26 carries the roller 18 that comes into contact with the cam 10. For this purpose, it has, for example, a bracket 30 for receiving the roller 18. The bracket 30 has a cylindrical shape with an axis BB parallel to the axis of rotation XX of the machine and a circular cross-section in a plane perpendicular to the axis BB. The bracket is open in the direction opposite to the foot.

[0072] Each housing 14 comprises a head region 66 and a foot region 68, which respectively house the head 26 and the foot 28 of the piston, and have a shape complementary to these parts of the piston. Thus, the foot region has a diameter, along a direction perpendicular to the axis PP of the housing, which is smaller than the diameter of the head region 66, along the same direction.

[0073] The foot region 68 is delimited by a main face 70 which in this case is cylindrical with a circular cross section in a plane perpendicular to the axis PP. The foot region has a secondary cavity 72: this secondary cavity

[0074] - cutting into the main surface 70,

[0075] - extends in a direction from the bottom 48 of the housing to the head region 66, and

[0076] - The piston 16 is not prevented from rotating.

[0077] The secondary cavity 72 is cylindrical with an axis parallel to the axis PP of the housing and, in this example, a circular cross section in a plane perpendicular to this axis. However, the cross section may be rectangular, triangular or other shapes.

[0078] In this case, the secondary cavity 72 opens into the head region 66 via one of its axial ends. The secondary cavity extends completely from the axis PP of the housing 14 to a distance that is smaller than the greater distance between the head region 66 and the axis PP. Therefore, the secondary cavity does not extend into the plane of the head region.

[0079] The cavity 72 extends completely for a certain distance from the middle plane of the housing, which is perpendicular to the axis of rotation XX. Here, the cavity is interrupted by a plane radial to this axis. The secondary cavity 72 is therefore arranged so as not to affect the functional surface of the foot area 68. It is known in practice that, due to the rolling of the roller 18 on the cam 10, the piston 16 is subjected to a circumferential force 50 relative to the axis of rotation XX during its travel in the housing 14, as in Figure 9 On the other hand, it is not subjected to axial forces 52, i.e. in a direction parallel to the axis XX. Therefore, the housing-piston assembly has a functional area 54 which is subjected to significant circumferential forces and for which the contact surface and the amount of contact material between the cylinder 12 and the piston 16 must be maintained. The functional area is the area of ​​the housing and the piston which extends in the circumferential direction, as in Figure 10 and Figure 11 The functional area 54 of the top of the housing 14 shown in the figure also serves for the piston foot 28. For this reason, the foot 28 allows a longer guidance of the piston along the axis PP in its area oriented in the circumferential direction to counteract circumferential forces.

[0080] With reference to the figures, in the cylinder 12, the supply ducts 22 have an end 46 forming the mouth of the corresponding housing 14. In this case, each duct 22 has a rectilinear shape and extends parallel to the axis of rotation XX. The supply ducts 22 open into the secondary chamber 72 and extend relative to the axis PP of the housing at the level of the foot region.

[0081] Figure 6 and Figure 7 The piston 16 is shown in the lower position and the upper position in the housing 14, respectively. Figure 6 As can be seen in FIG, in the low position, which is the position where the piston is closest to the bottom 48 of the housing, the foot 28 of the piston extends a distance from the mouth 46 of the supply conduit 22 and is unobstructed, in particular due to the presence of the secondary cavity 72. This secondary cavity allows the fluid that reaches the foot area 68 in motor mode to fill the housing and reach the head 26 of the piston with reduced interruptions and therefore reduced pressure losses. This is true even if the piston foot occupies the entire foot area 68, as in Figure 8 The variation shown in Figure 8The fluid flow is shown. The cross-section of the fluid passage near the supply conduit 22 is larger. This reduces pressure losses during filling and discharging. In fact, the same advantages exist in pump mode, when the piston pushes the fluid out of the housing into conduit 22 for discharging.

[0082] The cylinder 12 can be manufactured using conventional methods, in particular by forging or casting and then machining, given its general shape. In one embodiment of the manufacturing method, each secondary cavity 72 is made by machining using a tool (such as a milling cutter) by removing material.

[0083] During manufacture of the piston, for example by machining, a center point 76 may be made to allow for cylindrical grinding of the piston if desired. Figure 4 、 Figure 6 and Figure 7 As can be seen in FIG, this point has the form of a blind cavity that passes from the face 36 along the axis PP of the piston into the foot 28. This provides a grip that receives the tip for securing the piston between this tip and another grip (for example another tip received in the holder or on the head 26 before the holder is manufactured).

[0084] Second embodiment

[0085] Other embodiments will be described below. Features common to the first embodiment will not be described again.

[0086] In the composition Figure 12 In the machine of the second embodiment, each secondary cavity 72 does not have a cylindrical shape, which makes it more difficult to achieve by machining. The secondary cavity has an even greater depth as it gets closer to the bottom 48 of the housing 14. This allows the length of the bore of the guide tube 22 to be reduced.

[0087] At this point, the cylinder 12 obtains its general shape by casting, and the secondary cavity 72 of each housing is made by casting at that time (and therefore in the same step).

[0088] Third embodiment

[0089] exist Figures 13 to 17 In the third embodiment shown, the housing 14 further comprises a groove 62 configured to prevent the piston 16 from rotating relative to the housing 14 about the axis PP. The groove 62 is cut into a main surface 70 of the foot region 68 and extends in a straight line from the bottom 48 of the housing to the head region 66. The groove reaches the head region but not the bottom. In this case, the groove 62 has a generally cylindrical shape, with the axis of the cylinder parallel to the axis PP.

[0090] In addition, the piston 16 carries a pin 60 for preventing the piston from rotating. When the piston 16 is received in its housing 14, the pin is received in the groove 62, and the two cooperate to prevent the piston from rotating when the piston slides in the housing.

[0091] Unlike the groove 62, the secondary cavity 72 has dimensions insufficient to accommodate the pin 60, in particular a depth in a plane perpendicular to the axis PP, which provides error-proofing when receiving the piston in its housing. In fact, the operator cannot place the piston in its housing by trying to insert the pin into the secondary cavity.

[0092] As in Figure 14 As shown in FIG, similar to secondary cavity 72, groove 62 extends beyond functional region 54. Groove 62 and cavity 72 are located on either side of the midplane of cylinder 12, but are not diametrically opposed on either side of axis PP. Consequently, foot region 68 does not have a plane of symmetry. Their positions about the axis here form an angle α of approximately 150°.

[0093] For the production of the cylinder 12 , in this case the secondary cavity 72 and the groove 62 are produced in the foot region by removing material using the same tool, for example the same milling cutter.

[0094] Fourth embodiment

[0095] exist Figures 17 to 21 In the fourth embodiment of the machine shown, the machine is identical to that of the first embodiment except for the following features.

[0096] The piston foot 28 has a cavity 32 with a main axis CC. This cavity opens onto two opposite sides of the piston foot at two respective ends 34 of the cavity, which are opposite each other along the axis CC. In this case, the main axis CC of the cavity 32 is parallel to the axis of rotation XX of the machine. In this case, the cavity opens in the direction opposite to the head 26. This cavity extends to the free end of the foot 28, which is opposite to the head and is bounded by a cylindrical surface 36 oriented in the direction opposite to the head 26. This surface 36 has a generatrix parallel to the axis CC and perpendicular to the axis PP of the piston 16. In this case, the cavity has a circular cross-section.

[0097] In this case, the foot 28 has a side 40 that is divided into two cylindrical parts of different diameters along the axis PP, since the part of the foot closest to the head 26 has a reduced diameter. This face 40 is cut by two side faces 42 situated on either side of the axis PP. In this example, these side faces 42 form lateral cavities. Each of the lateral cavities here has a cylindrical shape, with a generatrix parallel to the axis PP (at Figure 20The side cavities each extend from the free end of the foot 28 to the head 26.

[0098] In this case, the free end of foot 28 has a bifurcated plane 44 perpendicular to axis PP and on either side of cavity 32. Piston 16 here has two planes of symmetry passing through its axis PP and perpendicular to each other (except for the pin when present).

[0099] The machine 2 is configured so that in the position where the piston 16 is closest to the bottom 48 of the housing 14, the piston leaves at least 50% of the cross-section of the mouth 46 of the conduit 22. Figure 18 and Figure 21 As can be seen in the figure, in this low position of piston 16, foot 28 provides a passage through it that, over its entire length, has a cross-section greater than or equal to 50% of the cross-section of supply duct 22 leading to housing 14. In this case, this cross-section of the passage is greater than or equal to the cross-section of duct 22. Due to the cylindrical shape of cavity 32, the fluid does not experience a reduction in the cross-section of the passage when passing through foot 28 in this position of piston 16. The cross-section through which the portion of the fluid intended to fill the lower portion of housing 14 passes does not experience a reduction in cross-section during its travel that would lead to pressure losses. On the contrary, the corresponding cross-section is never smaller than the corresponding cross-section of duct 22. The flow is thus improved and, in this position, flows along an axis parallel to the axis of rotation XX.

[0100] Cavity 32 is arranged so as not to affect the functional surface of piston foot 28. As already noted, the housing-piston assembly has a functional region 54 that is subject to significant circumferential forces. Other regions of foot 28, oriented parallel to axis XX and subject to lesser forces, can be subjected to the release of material. Main cavity 32 and the side cavity formed by secondary surface 42 are located outside this functional region 54 and therefore do not compromise performance in this regard.

[0101] Cavity 32 also allows piston foot 28 to deform more easily. In fact, in addition to the pressure loss, the release of material in the non-functional area of ​​the piston foot provides flexibility. This reduces stress concentrations on the lower portion of foot 28. A distinction is made between the favorable deformation area in the middle portion of face 36 closest to piston head 26 and the stress concentration areas at the ends of this face.

[0102] The cavity 32 is produced, for example, by milling.

[0103] As in Figure 20As shown in FIG, each side cavity formed by the side surface 42 of the piston has a dimension lp, perpendicular to the axis PP of the housing, that is greater than the dimension lc, along the same direction, of the secondary cavity 72 of the housing disposed opposite. This arrangement avoids the generation of burrs in the functional sliding area of ​​the piston foot 28 during machining of the secondary cavity 72. This also allows for simpler milling, if necessary.

[0104] Of course, many modifications can be made to the invention without departing from its scope.

[0105] The cylinder body 12 with the secondary cavity 72 can be made by casting, forging or additive manufacturing. The cavity can also be made by removing material, drilling, milling, drawing or profiling.

Claims

1. A hydraulic press (2), comprising: - a cylinder (12) having a housing (14), and - a piston (16) in the housing, Each housing includes a head region (66) and a foot region (68), The foot region is bounded by a main surface (70) and has a cavity (72): - cutting into the main surface (70), - extends in a direction from the bottom (48) of the housing to the head region, and - does not prevent the piston from rotating, The housing (14) further has a groove (62) configured to prevent rotation of the piston.

2. Machine according to the preceding claim, wherein The cavity (72) opens into the head region (66).

3. Machine according to at least one of the preceding claims, wherein The cavity (72) extends completely from the axis (PP) of the housing (14) a distance that is less than the greater distance between the head region (66) and the axis.

4. Machine according to at least one of the preceding claims, wherein The cavity (72) extends completely a distance from a mid-plane of the housing (14) perpendicular to the axis of rotation (XX) of the machine.

5. Machine according to at least one of the preceding claims, wherein The cavity (72) is cylindrical.

6. Machine according to at least one of the preceding claims, wherein The cavity (72) has an axis parallel to the axis of the housing (14).

7. Machine according to at least one of the preceding claims, wherein A supply conduit (22) opens into the cavity (72).

8. Machine according to at least one of the preceding claims, wherein A duct (22) for supplying the housing extends relative to the axis (PP) of the housing (14) at the level of the foot region (68).

9. Machine according to at least one of the preceding claims, wherein The piston comprises a foot (28) having a main face (40) and a secondary face (42) cut into the main face of the piston foot, the cavity (72) having a dimension (lc) along a direction perpendicular to the axis (PP) of the housing (14) that is smaller than a dimension (lp) of the secondary face along a direction perpendicular to the axis.

10. Machine according to at least one of the preceding claims, wherein The piston comprises a foot (28) having a piston foot cavity (32) opening to two opposite sides of the foot at two respective ends (46) of the piston foot cavity opposite to each other along a main axis (CC) of the piston foot cavity.

11. Machine according to at least one of the preceding claims, wherein The piston carries a pin (60) for preventing the piston from rotating, and the cavity (72) is of insufficient size to accommodate the pin.

12. Machine according to at least one of the preceding claims, wherein The housing (14) has no plane of symmetry.

13. A cylinder (12) for a hydraulic press, The cylinder (12) has a housing (14) comprising a head region (66) and a bottom region (68), The foot region is defined by a main surface (70) and comprises: - a cavity (72) cut into the main face and extending in a direction from the bottom of the housing (14) to the head region, and A groove (62) cut into the main face and extending completely a distance from the cavity (72) and in the direction of the axis (PP) of the housing (14).

14. A method for producing a cylinder (12) according to the preceding claim, wherein: The cavity (72) is formed by removing material.

15. A method for producing a cylinder (12) according to claim 13, wherein: The cavity (72) and the groove (62) are formed by removing material using the same tool.

16. A method for manufacturing a cylinder (12) according to claim 13, wherein: The cylinder body having the cavity (72) is manufactured by casting.

Images