Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
  • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
  • F04B1/20—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis having rotary cylinder block
  • F04B1/2014—Details or component parts
  • F04B1/2035—Cylinder barrels
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
  • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
  • F04B1/20—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis having rotary cylinder block
  • F04B1/2014—Details or component parts
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
  • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
  • F04B1/20—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis having rotary cylinder block
  • F04B1/2007—Arrangements for pressing the cylinder barrel against the valve plate, e.g. by fluid pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
  • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
  • F04B1/20—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis having rotary cylinder block
  • F04B1/22—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis having rotary cylinder block having two or more sets of cylinders or pistons
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
  • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
  • F04B1/26—Control
  • F04B1/30—Control of machines or pumps with rotary cylinder blocks
  • F04B1/32—Control of machines or pumps with rotary cylinder blocks by varying the relative positions of a swash plate and a cylinder block
  • F04B1/324—Control of machines or pumps with rotary cylinder blocks by varying the relative positions of a swash plate and a cylinder block by changing the inclination of the swash plate
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
  • F04B53/14—Pistons, piston-rods or piston-rod connections

Definitions

• the present invention relates to a hydraulic device according to the preamble of claim 1.
• Such a hydraulic device is known from WO 2006/083163.
• the shaft has a flange which extends perpendicularly to the first axis and the pistons are fixed to the flange at
• each piston head is ball-shaped. It is noted that the ball-shape creates a sealing line between the piston and the cylindrical sleeve which extends
• An object of the invention is to provide a hydraulic device which can be manufactured in a low-cost manner.
• each of the pistons has a modular structure comprising a piston head member which forms the piston head, a piston pin which is fixed to the flange and to which the piston head member is mounted, and a spacer which is located at the outer side of the piston pin and sandwiched between the piston head member and the flange.
• the piston head member may be manufactured by means of forging or stamping, for example.
• the spacer supports the piston head member with respect to the flange and may be clamped between the piston head member and the flange upon mounting the piston parts to the flange.
• play is present between the piston pin and the spacer. This means that a torque and/or a lateral force onto the piston can be absorbed by the flange rather than the piston pin, since under operating conditions the spacer is pressed against the flange by hydrostatic pressure in the compression chamber.
• the spacer is a bush, which surrounds the piston pin.
• the bush may have a concentrical and cylindrical inner and outer side. Such a bush can be
• the piston head member may have a central through- hole through which the piston pin extends.
• the piston head member may be fixed to the piston pin in axial direction of the piston pin through a press fitting between a surrounding wall of the central through-hole and an outer surface portion of the piston pin.
• the piston pin may partly extend beyond the piston head member as seen from the flange in order to minimize dead volume in the compression chamber if the extension protrudes in an oil discharge channel of the sleeve in top dead centre of the piston, for example. This has an advantageous effect on noise emission and hydraulic efficiency of the hydraulic device .
• the piston head member comprises a circular recess around a centre line of the piston pin at a side of the piston head member facing away from the flange.
• the piston head member has a
• circumferential wall including the ball-shaped circumferential outer side and an opposite inner side which borders the recess.
• the resulting circumferential wall has the following effect under operating conditions. Due to internal pressure in the compression chamber the cylindrical sleeve deforms in radial direction under operating conditions.
• the recess in the piston head member forms part of the compression chamber and serves to deform the piston head member at the sealing line such that expansion of the piston head member follows the sleeve expansion. Consequently, leakage flow between the piston and the cylindrical sleeve at the sealing line is minimized.
• the piston pin has a piston pin shank which is fixed to the flange and extends through the through-hole and a piston pin head, wherein the piston head member is sandwiched between the piston pin head and the spacer. Due to the presence of the piston pin head which has a larger diameter than the piston pin shank, axial fixing of the piston head member is relatively simple between the spacer and the piston pin head.
• a concave transition zone is present between the piston pin head and the piston pin shank, wherein the piston pin head and the piston head member contact each other within the transition zone, since this provides a more or less automatic centring position of the piston head member with respect to the piston pin.
• the piston head member is cup-shaped including a circumferential wall which has an inner side opposite to said ball-shaped circumferential outer side, which wall surrounds a cavity in which the piston pin head is located such that a circumferential outer side of the piston pin head faces the inner side of the circumferential wall of the piston head member.
• the cup-shaped piston head member provides a cavity which accommodates the piston pin head such that the height of the piston head member and the piston pin head together in longitudinal direction of the piston pin can be limited.
• a slot-shaped cavity is present between the inner side of the circumferential wall and the
• the cylindrical sleeve deforms in radial direction under operating conditions.
• the slot-shaped cavity in the piston head member forms part of the compression chamber and serves to deform the piston head member at the sealing line such that expansion of the piston head member follows the sleeve expansion. Consequently, leakage flow between the piston and the sleeve at the sealing line is minimized.
• the outer side of the piston pin head and the inner side of the circumferential wall of the piston head member may be parallel in circumferential direction.
• the piston pin head may partly extend beyond the piston head member as seen from the flange.
• a contact area between the spacer and the flange should be relatively large, for example larger than the cross-sectional area of the piston pin at the flange.
• the ratio may even be larger than two.
• Fig. 1 is a cross-sectional view of an embodiment of a hydraulic device according to the invention.
• Fig. 2 is a cross-sectional view of a part of the embodiment of Fig. 1 on a larger scale.
• Fig. 3 is a similar view as Fig. 2, but showing an alternative embodiment.
• Fig. 1 shows internal parts of a hydraulic device 1, such as a pump or hydromotor, which are fitted into a housing 27 in a known manner.
• the hydraulic device 1 is provided with a shaft 2 which is supported by bearings 3 at both sides of the housing 27 and which is rotatable about a first axis of rotation 4.
• the housing 27 is provided on the one side with an opening with a shaft seal 5 in a known manner, as a result of which the end of the shaft 2, which is provided with a toothed shaft end 6, protrudes from the housing 27.
• a motor can be coupled to the toothed shaft end 6 if the hydraulic device 1 is a pump, and a driven tool can be coupled thereto if the hydraulic device 1 is a motor.
• the hydraulic device 1 comprises face plates 7 which are mounted inside the housing 27 at a distance from each other.
• the face plates 7 have a fixed position with respect to the housing 27 in rotational direction thereof.
• the shaft 2 extends through central through-holes in the face plates 7.
• the shaft 2 is provided with a flange 8 which extends perpendicularly to the first axis of rotation 4.
• a plurality of pistons 9 are fixed at both sides of the flange 8 at equiangular distance about the first axis of rotation 4, in this case fourteen pistons 9 on either side.
• Each of the pistons 9 has a modular structure which will be explained hereinafter.
• the pistons 9 have centre lines which extend parallel to the first axis of rotation 4.
• the planes of the face plates 7 are angled with respect to each other and with respect to the plane of the flange 8 in the embodiment as shown in Fig . 1.
• Each of the pistons 9 cooperates with a cylindrical sleeve 10 to form a compression chamber 11 of variable volume.
• the hydraulic device 1 as shown in Fig. 1 has 28 compression chambers 11.
• the cylindrical sleeve 10 comprises a sleeve bottom 12 and a sleeve jacket 13.
• Each piston 9 is sealed directly to the inner wall of the sleeve jacket 13 through a piston head which is formed by a piston head member 14.
• the piston head member 14 is a part of the modular piston 9 and has a ball-shaped circumferential outer side.
• Fig. 2 shows the piston 9 including the piston head member 14 on a larger scale .
• each cylindrical sleeve 10 makes a combined translating and swivelling motion around the cooperating piston 9. Therefore, the outer side of each piston head member 14 is ball-shaped. The ball-shape creates a sealing line between the piston 9 and the cylindrical sleeve
• each piston 9 near the flange 8 is smaller than at the piston head member 14 in order to allow the relative motion of the cooperating cylindrical sleeves 10 about the pistons 9.
• the angle between the first axis of rotation and the respective second axes of rotation is approximately nine degrees in practice, but may be smaller or larger.
• the barrel plates 15 are pressed against the
• the compression chambers 11 communicate via a central through-hole in the respective sleeve bottoms 12 with cooperating passages 19 in the barrel plates 15.
• the passages 19 in the barrel plates 15 communicate via passages in the face plates 7 with a high-pressure port and a low-pressure port in the housing 27.
• Fig. 1 shows that each piston 9 is fixed to the flange 8 by means of a piston pin 20 which is pressed into a flange hole 21.
• Fig. 2 shows the press fitting for one piston 9.
• the flange 8 is provided with 28 flange holes 21, such that the pistons 9 on either side of the flange 8 alternately move into the top dead centre and bottom dead centre, which refers to the position where the volume of the compression chambers
• Fig. 2 shows one piston 9 of an embodiment of the hydraulic device 1.
• the piston head member 14 is cup-shaped and has a circumferential wall which has an inner side
• the piston pin 20 has a piston pin head 22 and a piston pin shank 23.
• the diameter of the piston pin head 22 is larger than that of the piston pin shank 23.
• the piston pin shank 23 extends through a central through-hole 24 of the piston head member 14 and an end portion of the piston pin shank 23 is clamped in the flange hole 21.
• the modular piston 9 also comprises a spacer in the form of bush 26 which surrounds the piston pin shank 23 and is sandwiched between the piston head member 14 and the flange 8. In the embodiment as shown the bush 26 has
• the piston head member 14 is fixed to the piston pin 20 in axial direction of the piston pin 20 through a clamp connection between the piston pin head 14 and the bush 26. More specifically, the piston pin 20 is provided with a concave transition zone between the piston pin head 22 and the piston pin shank 23, whereas the clamp connection is located within the transition zone where a surrounding edge of the central through hole 24 of the piston head member 14 contacts the piston pin 20. Outside this contact location the piston pin 20 is free from the piston head member 14.
• the circumferential wall of the piston head member 14 surrounds a cavity in which a part of the piston pin head 22 is located.
• circumferential wall is larger than the diameter of the piston pin head 22. Consequently, a slot-shaped cavity 25 is present between the inner side of the circumferential wall and the outer side of the piston pin head 22. This means that under operating conditions hydraulic fluid can enter the cavity 25 and exert a force onto the circumferential wall of the piston head member 14 in order to deform the piston head member 14, which has a beneficial effect on minimizing leakage between the piston 9 and the sleeve 10, as explained hereinbefore.
• the outer side of the piston pin head and the inner side of the circumferential wall of the piston head member 14 are parallel in circumferential
• piston pin head 22 partly extends beyond the piston head member 14 as seen from the flange 8.
• Fig. 3 shows one modular piston 9 of an alternative embodiment of the hydraulic device 1.
• the piston pin 20 does not have a wide piston pin head, but it has a constant diameter along its longitudinal direction.
• the piston head member 14 is fixed to the piston pin 20 in axial direction of the piston pin 20 through a press fitting between a circumferential surface of the central through-hole 24 and an outer surface portion of the piston pin 20.
• the piston head member 14 is mounted onto the piston pin 20 such that the piston pin 20 partly extends beyond the piston head member 14 as seen from the flange 8.
• the piston head member 14 comprises a circular recess 28 around the centre line of the piston pin 20 at a side of the piston head member 14 facing away from the flange.
• the recess 28 is comparable to the slot-shaped cavity 25 of the embodiment as shown in Fig. 2.
• the recess 28 is open in a direction directed from the flange 8 towards the piston head member 14.
• the modular piston 9 of the embodiment as shown in Fig. 3 also comprises a bush 26 which is sandwiched between the piston head member 14 and the flange 8.
• the bush 26 Upon assembly of the piston 9 of the embodiments as shown in Figs. 2 and 3 the bush 26 will be clamped between the piston head member 14 and the flange 8.
• the clamping force may be relatively small since a large clamping force will automatically be exerted by hydrostatic pressure in the compression chamber 11 under operating conditions of the hydraulic device 1.
• hydrostatic pressure appears to press the bush 26 against the flange 8 up to a high level such that a transverse force resulting from the
• the contact area should be relatively large, for example larger than the cross- sectional area of the corresponding flange hole 21.
• the outer diameter of the bush 26 may be at least 40% larger than its inner diameter.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Reciprocating Pumps (AREA)
• Pistons, Piston Rings, And Cylinders (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=58669668

Family Applications (1)

Country Status (5)

Families Citing this family (2)

Citations (4)

Family Cites Families (19)

• 2017
  • 2017-05-03 EP EP17169272.6A patent/EP3399186B1/en active Active
• 2018
  • 2018-05-02 JP JP2019559355A patent/JP7228249B2/ja active Active
  • 2018-05-02 CN CN201880026215.7A patent/CN110573731B/zh active Active
  • 2018-05-02 US US16/609,974 patent/US10961990B2/en active Active
  • 2018-05-02 WO PCT/EP2018/061117 patent/WO2018202665A1/en not_active Ceased

Patent Citations (4)

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