HYDRAULIC MACHINE

Abstract

A hydraulic machine includes a first member (1) having a first structure (2) for a hydraulic medium opening in a first interface surface (3) and a second member having a second structure for the hydraulic medium opening in a second interface surface is described, the first interface surface (3) being in contact with the second interface surface, wherein at least one of the members (1) is provided with a support element (6) surrounding the member (1). Such a machine should have a good efficiency. To this end the support element (6) has a strength varying in circumferential direction around the member (1) and/or in thickness direction in a middle region of the member (1).

Claims

1. A hydraulic machine comprising a first member having a first structure for a hydraulic medium opening in a first interface surface and a second member having a second structure for the hydraulic medium opening in a second interface surface, the first interface surface being in contact with the second interface surface, wherein at least one of the mem-bers is provided with a support element surrounding the member, wherein the support element comprises a strength varying in circumferential direction around the member and/or in thickness direction in a middle region of the member.

2. The hydraulic machine according to claim 1, wherein the strength of the support element varies depending on the resistance against deformation of the member in a direction parallel to its interface surface.

3. The hydraulic machine according to claim 1, wherein the shape of the cross section of the support element varies in circumferential direction around the member and/or in thickness direction in a middle region of the member.

4. The hydraulic machine according to claim 1, wherein the support element is in form of a compression ring connected to the member with an interference fit, wherein the interference fit varies in circumferential direction around the member and/or in thickness direction in a middle region of the member.

5. The hydraulic machine according to claim 1, wherein the structure for the hydraulic medium of the member comprises a first asymmetry and the support element comprises a second asymmetry compensating for the first asymmetry.

6. The hydraulic machine according to claim 1, wherein the member comprises a first outer form and the support element comprises a second outer form, wherein a distance between the first outer form and the second outer form varies in circumferential direction around the member and/or in thickness direction in a middle region of the member.

7. The hydraulic machine according to claim 1, wherein the support element comprises a contact face adjacent the member, wherein at least a part of the contact face in circumferential direction around the member and/or in thickness direction of the member forms a gap to the member.

8. The hydraulic machine according to claim 1, wherein the material of the member is different from the material of the support element.

9. The hydraulic machine according to claim 8, wherein the member is of a ceramic material.

10. The hydraulic machine according to claim 8, wherein the member is of a plastic material.

11. The hydraulic machine according to claim 8, wherein the support element is of stainless steel.

12. The hydraulic machine according to claim 1, wherein the support element is 3D printed.

13. The hydraulic machine according to claim 1, wherein the coefficient of thermal expansion of the member and of the support element differs no more than 10%.

14. The hydraulic machine according to claim 1, wherein the support element protrudes at least partly over the member at least in a part of the circumference of the member.

15. The hydraulic machine according to claim 1, wherein the interface surface is uneven without hydraulic pressure in a high pressure part of the structure for the hydraulic medium and even with hydraulic pressure in the high pressure part of the structure for the hydraulic medium.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Preferred embodiments of the invention will now be described with reference to the drawing, in which:

[0023] FIG. 1 is a schematic illustration showing forces acting in a member,

[0024] FIGS. 2a and 2b show sectional views through a part of the support element and a part of the member,

[0025] FIGS. 3a and 3b show schematically plan views of the member and the support element,

[0026] FIGS. 4a, 4b and 4c show a first embodiment of a member,

[0027] FIGS. 5a, 5b and 5c show a second embodiment of a member,

[0028] FIGS. 6a, 6b and 6c show a third embodiment of a member,

[0029] FIGS. 7a, 7b and 7c show a fourth embodiment of a member, and

[0030] FIGS. 8a and 8b show another member of a hydraulic machine.

DETAILED DESCRIPTION

[0031] FIG. 1 shows schematically a first member 1 of a hydraulic machine having a high-pressure channel 2 as a first structure for a hydraulic medium. The high-pressure channel 2 opens in a first interface surface 3. The first interface surface 3 forms a sealing surface with which the member 1 rests against a second member of the hydraulic machine which is not shown. The second member comprises likewise a second structure for the hydraulic medium which opens in a second interface surface which contacts the sealing surface 3. The contact between the two surfaces can be a static contact, i.e. a non-sliding contact, or it can be a sliding contact.

[0032] The port plate 1 comprises a port flange 4. During operation of the hydraulic machine the port plate 1 rotates in relation to the second member, for example the valve plate.

[0033] A number of arrows 5 shows possible deformations of the port flange 4 caused by the pressure of the hydraulic medium in the high-pressure channel 2 and the forces generated by these pressures.

[0034] In order to avoid these deformations, a support element 6, for example in form of a compression ring, is used. Arrows 7 show forces produced by the support element 6 and arrows 8 show deformations produced by these forces 7, i.e. by the forces produced by the support element 6. In an ideal situa-tion, the deformations 5 produced by the high pressure in the high-pressure channel 2 and the deformations 8 produced by the support element 6 are equal in opposite directions and cancel each other out, so that the flatness of the sealing surface 3 can be maintained.

[0035] However, the port flange 4 does not deform uniformly, but unevenly depending on its geometry.

[0036] To take into account this uneven deformation, the support element 6 produces forces counteracting the deformations produced by the high pressure of the hydraulic medium which are also unevenly distributed. These forces are briefly termed “strength”. This strength of the support element 6 varies in the circumferential direction around the member 1. Alternatively or additionally, this strength can vary in the thickness direction, in particular in a middle region of the member 1, i.e. the variation of the strength of the support member 6 is not limited to its edges.

[0037] This is schematically shown in FIG. 2. FIG. 2 shows a cross section through a part of the port flange 4 and a part of the support element 6.

[0038] In FIG. 2a a support element 6 has a cross section in form of a tri-angle. The radial extension of the support element 6 increases from the lower end of the support element 6 to the upper end of the support element 6 (as shown in FIG. 1). In other words, the thickness of the support element 6 is larg-est in the region of the sealing surface 3, so that the resistance against deformation of the port flange 4 in a region of the sealing surface 3 can be minimized.

[0039] FIG. 2b shows an alternative cross section of the support element 6. Here, the radial extension of the support element 6 increases from the bottom to approximately the middle of the thickness of the port flange 4 and is then con-stant short before the upper end of the port flange 4. Then the radial extension of the support element 6 slightly decreases.

[0040] This means that the strength of the support element 6 is highest in the “upper half” of the port flange (as shown in FIG. 2b).

[0041] FIG. 3 schematically shows in a top view the port flange surrounded by the support element 6. It can be seen, that the port flange 4 is of circular form, while the support element 6 is of elliptic form. Thus, there are two gaps 9, 10 between the port flange and the support element 6. In these gaps 9, 10 there are no compression forces produced by the support element 6 acting on the port flange 4.

[0042] FIG. 3b shows an embodiment in which the port flange 4 is of circular form and the support element 6 is in form of a ring having an outer contour which is also of circular form. The inner contour of the support element 6 is also of circular form. However, there are three gaps 9, 10, 11 between the port flange 4 and the support element 6 in which no compression forces are produced.

[0043] FIG. 4 shows an embodiment of the member 1, wherein FIG. 4a shows the member 1 from one side, FIG. 4b shows the member 1 from the opposite side and FIG. 4c shows a sectional view through a middle plane of the member 1.

[0044] The port flange 4 comprises two kidney-shaped openings 12, 13 which are connected with inlet and outlet openings 14, 15, respectively. The inlet and outlet openings 14, 15 can be connected, for example, with cylinders. The support element 6 is in form of a compression ring. The shape of the support element 6 varies in circumferential direction. In this case, the port flange 4 comprises a first outer form which is circular and the support element 6 comprises a second outer form, which is not circular. A distance between the outer form of the port flange and the outer form of the support element 6 varies in circumferential direction. In other words, there are sections 16 in which the support element 6 is thinner, and sections 17, in which the support element 6 is thicker (all in radial direction). This means that the support element 6 has a strength which is larger in the regions 17 than in the regions 16.

[0045] FIG. 5 shows another embodiment in which the port flange 4 is surrounded by the support element 6. Again, FIG. 5a shows the member 1 from one side, FIG. 5b shows the member from the other side, and FIG. 5c shows a sectional view. The support element 6 has a varying shape in the thickness direction of the member 1. The variation of the radial extension of the support element 6 is prominent in a middle part 18 of the thickness of the support element 6. This means, that the strength of the support element 6 is highest in the middle part of the thickness of the member 1.

[0046] FIG. 6 shows an embodiment of the invention in which the support element is again in form of a compression ring. Again, FIG. 6a shows member 1 from one side, FIG. 6b shows the member 1 from the other side, and FIG. 6c shows a sectional view. The support element 6 has a strength varying in the circumferential direction around the port flange and in the thickness direction of the port flange 4 between the two edges of the port plate 1.

[0047] Another embodiment of the invention is shown in FIG. 7, in which the support element 6 again has two regions in the circumferential direction which are in the side of the kidney-shaped openings 12, 13 larger in the radial extension. Again, FIG. 7a shows the member 1 from one side, FIG. 7b shows the member 1 from the other side, and FIG. 7c shows a sectional view. However, the larger radial extension is limited to only the half of the thickness of the port flange 41 in which the kidney-shaped openings 12, 13 are arranged.

[0048] FIG. 8 shows a second member of the hydraulic machine in form of a valve plate 19 having kidney-shaped openings 20, 21. A rib 22, 23 has been introduced in each kidney-shaped opening 20, 21 to prevent the support element 6 to damage the kidney-shaped openings 20, 21. However, when the support element 6 is provided with a varying strength, this rib 22, 23 can be omitted.

[0049] Again, the support element 6 shows a radial extension which varies in circumferential direction and in the thickness direction of the valve plate 19.

[0050] As can be seen in FIG. 8b, the valve plate 19 comprises a first asymmetry 24 and the support element 6 comprises a second asymmetry 25. The second asymmetry 25 compensates for the first asymmetry 24.

[0051] The port flange 4 and the support element 6 can be of different materials. The same is true for the valve plate 19 and the support element 6. The valve plate 19 and/or the port flange 4 can be of a plastic material or of a ceramic material. The support element 6 can be of steel, in particular stainless steel.

[0052] The support element 6 can be produced by 3D-printing.

[0053] The coefficient of thermal expansion of the support element 6 and the port flange 4 or the valve plate 19, respectively, should be close to each other. In other words, the coefficient of thermal expansion of the port flange, the valve plate 19 and the support element 6 differs no more than 10%.

[0054] The support element 6 can protrude at least partially over the port flange 4 or valve plate 19, at least in a part of the circumference of the port plate 1 or the valve plate 19, respectively.

[0055] It is possible to make the sealing surface 3 uneven in a condition where there is no hydraulic pressure in the high-pressure channel 2, i.e. the forces produced by the support element 6 lead to a deformation of the sealing surface 3. This deformation is compensated for when the hydraulic pressure in the high-pressure channel 2 increases, so that, for example, at a pressure of 80 bars, the required flatness is achieved.

[0056] While the present disclosure has been illustrated and described with respect to a particular embodiment thereof, it should be appreciated by those of ordinary skill in the art that various modifications to this disclosure may be made without departing from the spirit and scope of the present disclosure.