RADIAL PISTON PUMP, METHOD FOR OPERATING A RADIAL PISTON PUMP, AND STEERING SYSTEM

Abstract

A radial piston pump for delivering a pressure medium to a consumer may include a housing in which cylinder bores are arranged radially to a longitudinal axis and in each of which a radially displaceable piston is arranged. The pistons form a piston row lying in a radial plane. The radial piston pump furthermore has an eccentric shaft arranged coaxially to the longitudinal axis which sets the pistons in a linearly oscillating reciprocating motion, wherein pressure medium flows into cylinder chambers through suction openings formed in the piston in the region of a bottom dead centre of the stroke movement, from a suction chamber which is supplied with pressure medium through a suction port. The pressure medium flows out of the cylinder chambers to a pressure outlet through pressure openings owing to movement of the pistons towards the top dead centre. At least one further piston row is provided planar-parallel to the piston row. Further cylinder bores are provided in the housing, in each of which a piston of the further piston row is radially displaceably arranged. The eccentric shaft sets the pistons of the further piston row in a linearly oscillating reciprocating motion.

Claims

1. A radial piston pump for delivering a pressure medium to a consumer, said pump comprising: an eccentric shaft having a longitudinal axis; a housing having first cylinder bores which are arranged radially to the longitudinal axis, the housing further having (i) a suction port supplied with the pressure medium, (ii) a suction chamber which is supplied with the pressure medium through the suction port, and (iii) a first pressure outlet; a respective first piston disposed radially displaceably in each of the first cylinder bores, the first pistons being arranged in a first piston row which lies in a radial plane, each of the first pistons having a respective suction opening, the eccentric shaft being mounted in the housing for rotation about the longitudinal axis for moving the first pistons in a first linearly oscillating reciprocating motion having a top dead center and a bottom dead center, and wherein, in a region of the bottom dead center of the first linearly oscillating reciprocating motion, the pressure medium flows into cylinder chambers through the suction openings of the first pistons, and wherein the pressure medium flows out of the cylinder chambers to the first pressure outlet through pressure openings owing to movement of the first pistons towards the top dead center of the first linearly oscillating reciprocating motion; and wherein further cylinder bores are provided in the housing and a respective second piston is disposed radially displaceably in each of the further cylinder bores, the second pistons being arranged in at least one further piston row which is located planar-parallel to the first piston row, and wherein the eccentric shaft moves the second pistons of the further piston row in a second linearly oscillating reciprocating motion.

2. A radial piston pump according to claim 1, wherein the eccentric shaft includes at least one first eccentric region which moves the first pistons of the first piston row in the first linearly oscillating reciprocating motion and wherein the eccentric shaft further includes at least one second eccentric region which moves the second pistons of the further piston row in the second linearly oscillating reciprocating motion.

3. A radial piston pump according to claim 1, wherein the pressure medium flows into cylinder chambers from the suction chamber through suction openings formed in the pistons of the further piston row in the region of a bottom dead center of the stroke movement, and wherein the pressure medium flows out of the cylinder chambers via pressure openings owing to a movement of the pistons towards the top dead center.

4. A radial piston pump according to claim 1, wherein the housing includes a further pressure outlet and the second pistons of the further piston row deliver the pressure medium to the further pressure outlet.

5. A radial piston pump according to claim 4, wherein the first pressure outlet is connected to a first consumer and the further pressure outlet is connected to a second consumer in order to deliver the pressure medium to the first consumer and the second consumer.

6. A radial piston pump according to claim 4 wherein, the first pressure outlet and the further pressure outlet are connected to one consumer in order to deliver the pressure medium to the same one consumer.

7. A radial piston pump according to claim 6, further comprising a control device configured to control delivery of the pressure medium to the same one consumer from both the first pressure outlet and the further pressure outlet or from only one of the first pressure outlet and the further pressure outlet.

8. A radial piston pump according to claim 1, wherein the first piston row and the further piston row are configured such that a volume of the pressure medium delivered by the first piston row upon a rotation of the eccentric shaft differs from a volume of the pressure medium delivered by the further piston row upon the rotation of the eccentric shaft.

9. A radial piston pump according to claim 1, further comprising a dedicated first slide ring arranged between the eccentric shaft and the first piston row and a dedicated second slide ring arranged between the eccentric shaft and the further piston row.

10. A radial piston pump according to claim 9, wherein a thickness of the first slide ring in a radial direction differs from a thickness of the second slide ring in the radial direction.

11. A radial piston pump according to claim 1, wherein the radial piston pump is configured as an emergency steering pump for a vehicle and wherein the first piston row is configured to deliver the pressure medium to a wheel steering gear or a steering cylinder of a steering system of a first wheel axle of the vehicle, and the further piston row is configured to deliver the pressure medium to a wheel steering gear or a steering cylinder of a steering system of a second wheel axle of the vehicle.

12. A method for operating a radial piston pump for delivering a pressure medium to a first consumer, wherein the radial piston pump has a housing in which cylinder bores are arranged radially to a longitudinal axis and in each of which a respective radially displaceable first piston is arranged, wherein the pistons form a first piston row lying in a radial plane, and wherein the first pistons are set in a linearly oscillating reciprocating motion by rotation of an eccentric shaft mounted in the housing for rotation about the longitudinal axis, and wherein the pressure medium flows into cylinder chambers through suction openings of the first pistons in the region of a bottom dead center of the motion, from a suction chamber which is supplied with the pressure medium through a suction port under a vacuum created by the movement of the first pistons towards a bottom dead center of the motion, and wherein the pressure medium is delivered via pressure openings to a pressure outlet on movement of the first pistons towards the top dead center, and wherein at least one further piston row is provided planar-parallel to the first piston row, and further cylinder bores are provided in the housing, in each of which a respective second piston of the further piston row is radially displaceably arranged, and the second pistons of the further piston row are set in a linearly oscillating reciprocating motion by rotation of the eccentric shaft, whereupon the pressure medium delivered by the piston row and the further piston row is supplied to the same consumer or the pressure medium delivered by the first piston row is supplied to the first consumer and the pressure medium delivered by the further piston row is supplied to a second consumer.

13. A method according to claim 12, wherein when the pressure medium is delivered to the same consumer, it is provided that, as required, only the pressure medium delivered by the first piston row or only the pressure medium delivered by the further piston row or the pressure medium delivered by both piston rows is supplied to the consumer.

14. A method according to claim 12, wherein a volume of the pressure medium which the first piston row delivers upon a rotation of the eccentric shaft differs from a volume of the pressure medium delivered by the further piston row upon the rotation of the eccentric shaft.

15. A method according to claim 12, wherein the pressure medium delivered by the first piston row is supplied to a first consumer and the pressure medium delivered by the further piston row is supplied to a second consumer, the first consumer being a first steering system of a first steerable wheel axle of a vehicle and the second consumer being a steering system of a second steerable wheel axle of the vehicle.

16. A steering system for a vehicle of the type having at least a first steerable wheel axle which in normal operation can be deflected by a first steering device and a second steerable wheel axle which in normal operation can be deflected by a second steering device, said system, comprising: an emergency pump configured as a radial piston pump, the radial pump including: (a) an eccentric shaft having a longitudinal axis; (b) a housing having first cylinder bores which are arranged radially to the longitudinal axis, the housing further having (i) a suction port supplied with a pressure medium, (ii) a suction chamber which is supplied with the pressure medium through the suction port and (iii) a pressure outlet, and (c) a respective first piston disposed radially displaceably in each of the first cylinder bores, the first pistons being arranged in a first piston row which lies in a radial plane, each of the first pistons having a respective suction opening, the eccentric shaft being mounted in the housing for rotation about the longitudinal axis for moving the first pistons in a first linearly oscillating reciprocating motion having a top dead center and a bottom dead center, and wherein, in a region of the bottom dead center of the first linearly oscillating reciprocating motion, the pressure medium flows into cylinder chambers through the suction openings of the first pistons, and wherein the pressure medium flows out of the cylinder chambers to the pressure outlet through pressure openings owing to movement of the first pistons towards the top dead center of the first linearly oscillating reciprocating motion; and wherein further cylinder bores are provided in the housing and a respective second piston is disposed radially displaceably in each of the further cylinder bores, the second pistons being arranged in at least one further piston row which is located planar-parallel to the first piston row, and wherein the eccentric shaft moves the second pistons of the further piston row in a second linearly oscillating reciprocating motion; and wherein said system further comprises first pressure lines to supply the pressure medium delivered by the first piston row to a wheel steering gear or a steering cylinder of the first steering device of the vehicle, and further pressure lines to supply the pressure medium delivered by the further piston row to a wheel steering gear or a steering cylinder of the second steering device of the vehicle.

17. A radial piston pump according to claim 1, wherein the first piston row and the further piston row are configured such that a pressure of the pressure medium originating from the first piston row differs from a pressure of the pressure medium originating from the further piston row.

18. A method according to claim 12, wherein a pressure of the pressure medium originating from the first piston row upon a rotation of the eccentric shaft differs from a pressure of the pressure medium originating from the further piston row upon the rotation of the eccentric shaft.

19. A method according to claim 15, wherein the radial piston pump is an emergency steering pump of the vehicle and wherein the first consumer comprises a first wheel steering gear of the first steering system of the first steerable wheel axle of the vehicle and the second consumer comprises a second wheel steering gear of the second steering system of the second steerable wheel axle of the vehicle.

20. A method according to claim 15, wherein the radial piston pump is an emergency steering pump of the vehicle and wherein the first consumer comprises a first steering cylinder of the first steering system of the first steerable wheel axle and the second consumer comprises a second steering cylinder of the second steering system of the second wheel axle.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0078] In the drawings:

[0079] FIG. 1 shows a cross-section through a possible embodiment of a radial piston pump; and

[0080] FIG. 2 shows a schematic illustration of the supply of two consumers by a radial piston pump according to the invention.

DETAILED DESCRIPTION

[0081] As evident from FIGS. 1 and 2, the radial piston pump 1 according to the invention for delivering a pressure medium to a consumer 2, which is also referred to below as the first consumer 2, has a housing 3 in which multiple cylinder bores 5 are provided which are arranged radially to a longitudinal axis 4.

[0082] In the exemplary embodiment, six to ten, preferably eight cylinder bores 5 are provided. A radially displaceable piston 6 is arranged in each of the cylinder bores 5. The pistons 6 form a piston row 7 lying in a radial plane. The radial plane here refers to the longitudinal axis 4. In this exemplary embodiment, the piston row 7 is also described as the first piston row 7.

[0083] The radial piston pump 1 furthermore has an eccentric shaft 8 which is arranged coaxially to the longitudinal axis 4 and sets the pistons 6 in a linearly oscillating reciprocal motion. When the piston 6 is in the region of a bottom dead center of the stroke movement, pressure medium is drawn into a cylinder chamber 12 through suction openings 9 formed in the piston 6, from a suction chamber 10 which is supplied with pressure medium through a suction port 11. The cylinder chamber 12 may here be described as a displacement chamber.

[0084] By a movement of the piston 6 towards the top dead center, the pressure medium is pressed out of the cylinder chamber 12 to a pressure outlet 14, or flows in the direction of the pressure outlet 14, through pressure openings 13. By deviation from the design of conventional radial piston pumps, the radial piston pump 1 according to the invention, as illustrated for example in the exemplary embodiment, has at least one further piston row 15 arranged planar-parallel to the first piston row 7. The further piston row 15 is also called the second piston row 15. Further cylinder bores 16 are provided in the housing 3, in each of which a piston 17 of the further piston row 15 is radially displaceably arranged. The eccentric shaft 8 sets the pistons 17 of the further piston row 15 in a linearly oscillating reciprocating motion.

[0085] It is pointed out that the radial piston pump 1 illustrated in the exemplary embodiment is particularly advantageous, although deviations therefrom are possible. In particular, a third piston row or a fourth piston row or even further piston rows may also be provided, which are preferably identical in structure to the first piston row 7 or second piston row 15.

[0086] In the exemplary embodiment, it is provided that the second piston row 15 also has six to ten, preferably eight pistons 17, i.e. that a corresponding number of cylinder bores 16 is provided.

[0087] In the exemplary embodiment, it is furthermore provided that pressure medium flows into a cylinder chamber 12 through suction openings 9 formed in the pistons 17 in the region of a bottom dead center of the stroke movement. On movement of the pistons 17 towards the top dead center, the pressure medium flows out of the cylinder chamber 12 again or is pressed out through pressure openings 13.

[0088] The structure of the cylinder bores 16 and pistons 17 may preferably be identical to the structure of the cylinder bores 5 and pistons 6.

[0089] In the exemplary embodiment, it may be provided that the cylinder bores 5 or pistons 6 have a different diameter and/or different length from the cylinder bores 16 or pistons 17.

[0090] In the exemplary embodiment, the eccentric shaft 8 is configured as a double eccentric shaft. The eccentric shaft 8 here has a first eccentric region 18 which, when the eccentric shaft rotates, sets the pistons 6 of the first piston row 7 in a reciprocating motion. Furthermore, the eccentric shaft 8 has a second eccentric region 19 which sets the pistons 17 of the second piston row 15 in a reciprocating motion.

[0091] As furthermore evident from FIG. 1, for each piston row 7, 15, a dedicated slide ring 20 is provided. In the exemplary embodiment, the slide rings 20 are arranged on the eccentric shaft 8, more precisely on the first eccentric region 18 and second eccentric region 19. The slide rings 20 are situated between the eccentric shaft 8 or eccentric regions 18, 19 and the respective piston row 7 or 15.

[0092] In the exemplary embodiment, the two slide rings 20 are shown with identical thickness in the radial direction. It may however also be provided that the slide rings 20 have a different thickness in the radial direction.

[0093] As evident from FIG. 1, the radial piston pump I has a further pressure outlet 21 formed in the housing 3. The further pressure outlet 21, which may also be called the second pressure outlet 21, is supplied with pressure medium by the pistons 17 of the second piston row 15.

[0094] In the exemplary embodiment, it may be provided that the pressure outlet 14, which may also be called the first pressure outlet 14, and the second pressure outlet 21 serve to deliver pressure medium to the same consumer 2.

[0095] However, in the exemplary embodiment, a design is shown in which it is provided that the first pressure outlet 14 is connected to the first consumer 2, and the second pressure outlet 21 is connected to a second consumer 22. Thus the respective pressure outlet 14, 21 can deliver pressure medium to the respective connected consumer 2 or 22.

[0096] In the exemplary embodiment, it may be provided that the piston rows 7, 15 are configured such that the volume of pressure medium delivered by the first piston row 7 on a rotation of the eccentric shaft 8 differs from the volume delivered by the second piston row 15. Alternatively and/or additionally, it may also be provided that the radial piston pump 1 is configured such that the pressure of the pressure medium originating from the first piston row 7 differs from the pressure of the pressure medium originating from the further/second piston row 15.

[0097] In the exemplary embodiment, for simplification it is provided that the piston rows 7, 15 supply or pressurize the consumers 2, 22 with the same volume and same pressure of the pressure medium on a constant rotation of the eccentric shaft. However, depending on the consumers 2, 22, it may be suitable to select a different volume or different pressure for the respective consumer 2, 22.

[0098] The present exemplary embodiment also serves to disclose the method according to the invention for operating a radial piston pump 1.

[0099] Operation of the radial piston pump 1 is particularly suitable if the first consumer 2 is a first steerable wheel axle, and the second consumer 22 is a second steerable wheel axle of a utility vehicle (not shown in more detail), in particular an agricultural utility vehicle. In principle, this may also be a vehicle in general.

[0100] The method according to the invention is quite particularly suitable if the radial piston pump 1 is configured as an emergency steering pump, wherein the first consumer 2 may be a wheel steering gear or a steering cylinder of a steering device of the first wheel axle, and the second consumer 22 may be a wheel steering gear or steering cylinder of a steering device of the second wheel axle.

[0101] FIG. 2 illustrates a circuit of the radial piston pump 1, wherein pressure medium flows from a pressure outlet 14 to a first consumer 2 and from there back to a pressure medium reservoir 23. Pressure medium is delivered from the second pressure outlet 21 to the second consumer 22 and from there again back to the pressure medium reservoir 23. FIG. 2 also shows as an example a drive shaft or the eccentric shaft 8.

[0102] FIG. 2 also shows that the consumers 2, 22 may be parts of the steering system 24.

[0103] The exemplary embodiment also serves to disclose an exemplary steering system 24 for a vehicle, in particular a utility vehicle and quite particularly an agricultural utility vehicle, with at least two steerable wheel axles which, in the exemplary embodiment of FIG. 2, may be the consumers 2, 22. In a manner not shown in detail, the two steerable wheel axles can each be deflected in normal operation by an electric and/or hydraulic steering device which is part of the steering system 24.

[0104] The radial piston pump 1 here serves as an emergency steering pump which is configured according to the invention and/or operated using the method according to the invention.

[0105] In the context of the steering system 24. pressure lines are provided for supplying a pressure medium delivered by the first piston row 7 to a wheel steering gear or steering cylinder of a steering device of the first wheel axle (=consumer 2). Furthermore, further pressure lines may be provided for supplying a pressure medium delivered by the second piston row 15 to a wheel steering gear or steering cylinder of a steering device of the second wheel axle (=consumer 22).

[0106] The radial piston pump 1 shown in FIG. 1 is preferably a suction-regulated radial piston pump with dual-row design. The radially arranged pistons 6, 17 are set in a linearly oscillating reciprocating motion by the common rotating double eccentric shaft 8 in conjunction with springs 25 in the pistons 6, 17. At the bottom dead center of the stroke movement, the preferably radial suction openings-which may be suction bores-in the piston 6 or 17 dip into the suction chamber 10, which may also be described as an eccentric chamber. Under the vacuum created in the cylinder chamber 12 by of the movement of the pistons 6, 17 to the bottom dead center, pressure medium flows into the cylinder chamber 12 when the preferably radial suction openings 9 open. The pressure medium is preferably a hydraulic fluid, in particular an oil.

[0107] On movement of the pistons 6, 17 towards the top dead center, the pressure medium is delivered to the pressure outlet 14 or 21 through the pressure openings 13which may also be called outlet boresand check valves which are preferably provided (not designated in more detail). Each of the pressure outlets 14, 21 is connected to a piston row 7, 15. This allows the supply of pressure medium to separate consumers 2, 22. The principle of suction regulation allows variable delivery quantities of pressure medium by suitable combinations of piston 6, 17, slide ring 20 and the eccentricity of the eccentric shaft 8. Thus it is possible to provide different delivery quantities for the respective circuits. Because of the common drive, the eccentric shaft 8 and the suction port 11, a flexible dual-circuit configuration is possible with compact construction.

LIST OF REFERENCE SIGNS

[0108] 1 Radial piston pump [0109] 2 (First) consumer [0110] 3 Housing [0111] 4 Longitudinal axis [0112] 5 Cylinder bore [0113] 6 Piston [0114] 7 (First) piston row [0115] 8 Eccentric shaft [0116] 9 Suction openings [0117] 10 Suction chamber [0118] 11 Suction port [0119] 12 Cylinder chamber [0120] 13 Pressure openings [0121] 14 (First) pressure outlet [0122] 15 (Further/second) piston row [0123] 16 (Further) cylinder bores [0124] 17 (Further) pistons (of 15) [0125] 18 First eccentric region [0126] 19 Second eccentric region [0127] 20 Slide ring [0128] 21 (Further/second) pressure outlet [0129] 22 (Second) consumer [0130] 23 Pressure medium reservoir [0131] 24 Steering system [0132] 25 Springs [0133] Q Volume [0134] P Pressure

[0135] What is claimed is: