Hydrostatic axial piston machine

Abstract

A hydrostatic axial piston machine includes a double-acting actuating cylinder configured to adjust the piston displacement. The actuating cylinder has two actuating chambers that are connected to two spatially separated cartridge valves. The two cartridge valves are inserted obliquely into a wall section of the axial piston machine. The wall section on the one hand forms a wall of the housing of the axial piston machine and on the other hand forms a wall of the actuating cylinder.

Claims

1. A hydrostatic axial piston machine comprising: a drive shaft; an actuating piston configured to be moved in an actuating piston plane arranged perpendicularly to the drive shaft; and a swashplate configured to be adjusted across a neutral point by the actuating piston, wherein the actuating piston delimits two actuating chambers acting against each other to which pressurized actuating medium is configured to be respectively supplied via a respective control valve and from which pressurized actuating medium is configured to be respectively released via the respective control valve, and wherein respective valve bodies of the two control valves are arranged obliquely to the drive shaft and obliquely to the actuating piston plane.

2. The axial piston machine according to claim 1, wherein the two valve bodies have a parallel distance from each other and are arranged in a valve body plane that is oblique to the drive shaft and oblique to the actuating piston plane, and wherein the valve body plane is arranged between the actuating piston and a cylinder barrel.

3. The axial piston machine according to claim 1, wherein the two valve bodies are accommodated inside an outer side of a housing of the axial piston machine.

4. The axial piston machine according to claim 3, wherein the two control valves are cartridge valves, the valve housings of which are configured as cartridges that are inserted into respective installation holes of the housing of the axial piston machine.

5. The axial piston machine according to claim 4, wherein the two cartridges have in each case sockets on the side for screws, via which the cartridges are configured to be fastened in the respective installation holes.

6. The axial piston machine according to claim 4, wherein the two installation holes penetrate the housing of the axial piston machine and open into an interior space of the housing, and wherein a respective tank port is arranged on respective inner end sections of the two cartridges.

7. The axial piston machine according to claim 6, wherein on respective outer circumferences of the two inner end sections a respective connection is formed between the interior space of the housing and the respective tank port.

8. The axial piston machine according to claim 4, wherein a respective actuating pressure port is arranged on respective outer circumferences of the two cartridges, the respective actuating pressure port connected via a respective actuating pressure passage to the respective actuating chamber.

9. The axial piston machine according to claim 4, wherein the two actuating pressure passages are configured as respective communication bores between a respective connecting bore and the respective installation hole, the respective connecting bore closed off by a seal.

10. The axial piston machine according to claim 9, wherein: the two connecting bores are arranged parallel to the actuating piston plane, the two communication bores are arranged obliquely to the respective connecting bore and obliquely to the respective installation hole, and a diameter of the two communication bores is smaller than a diameter of the two connecting bores.

11. The axial piston machine according to claim 8, wherein the two installation holes penetrate the housing of the axial piston machine and open into an interior space of the housing, a respective tank port arranged on respective inner end sections of the two cartridges, and wherein a feed pressure port is formed in each case on the two outer circumferences of the cartridges, the actuating pressure port arranged in each case between the tank port and the feed pressure port.

12. The axial piston machine according to claim 11, wherein the feed pressure port of the first control valve is connected via a first feed pressure passage to a feed pump, and wherein the feed pressure port of the second control valve is connected via a second feed pressure passage to the feed pressure port of the first control valve.

13. The axial piston machine according to claim 1, wherein the two control valves are pressure control valves in each case, and wherein the two valve bodies are acted upon by the respective actuating pressure with a respective resulting force which together with a respective spring acts upon the respective valve body in the direction of a release of pressurized actuating medium from the respectively connected actuating chamber.

14. The axial piston machine according claim 13, wherein: the two control valves are cartridge valves, the valve housings of which are configured as cartridges that are inserted into respective installation holes of the housing of the axial piston machine, the two installation holes penetrate the housing of the axial piston machine and open into an interior space of the housing, and a respective tank port is arranged on respective inner end sections of the two cartridges, a respective larger end face, which is acted upon by the actuating pressure and on which also acts the respective spring, is formed on the respective valve body in the two inner end sections of the cartridges, and a respective further smaller end face, which is acted upon by the actuating pressure and acts against the larger end face and the spring, is formed on the respective valve body.

15. The axial piston machine according to claim 14, wherein a respective end face, which is arranged on the inner end section of the two cartridges, is closed by a respective spring plate on which is supported the respective spring, and wherein the respective larger end face, which is acted upon by the actuating pressure, is arranged in the respective inner end section of the two cartridges.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An exemplary embodiment of an axial piston machine according to the disclosure is shown in the drawings. The disclosure is now explained in more detail with reference to the figures of these drawings.

(2) In the drawings:

(3) FIG. 1 shows in a plan view an axial piston machine according to the disclosure according to the exemplary embodiment;

(4) FIG. 2 shows a longitudinal section through the axial piston machine from FIG. 1;

(5) FIG. 3 shows a section along the line D-D from FIG. 2; and

(6) FIG. 4 shows in a longitudinal section a pressure control valve of an adjustment device of the axial piston machine from FIG. 1.

DETAILED DESCRIPTION

(7) FIG. 1 shows a plan view of a housing of an axial piston machine according to the disclosure which is designed as an axial piston pump. The housing has a first housing section 2 and a second housing section 4. Formed in one piece and integrally with the first housing section 2 is an actuating cylinder 6 which has an adjustment device for the pivot angle of a swashplate (not shown in FIG. 1) of the axial piston machine. As a result, the piston displacement of the axial piston machine can be adjusted from a neutral point in two different directions. Therefore, a delivery direction during pumping operation of the axial piston machine can be varied and furthermore steplessly adjusted.

(8) The swashplate is connected to an actuating piston which separates two actuating chambers of the actuating cylinder 6 from each other. For the filling or for the supplying of the actuating chambers with pressurized actuating medium and for the emptying or releasing of pressurized actuating medium from the actuating chambers, a respective pressure control valve 8, 10 is fastened on the first housing section 2. The pressure control valves 8, 10 are designed as cartridge valves which are inserted, at least in certain sections, into the first housing section 2 and are fixed there by two screws 12 in each case. In this case, the two pressure control valves 8, 10 have in each case a flange 14 on which are formed two oppositely disposed, roughly U-shaped, recesses which are provided as sockets for the screws 12.

(9) Via the adjustment device, which is explained more accurately with regard to the following figures, the swashplate can be pivoted in relation to an axis 16 of a drive shaft 18. In this case, the adjustment device is constructed as a transverse adjustment device in which the actuating piston (not shown) of the actuating cylinder 6 can be moved along an actuating piston plane 20 which is arranged perpendicularly to the axis 16 of the drive shaft 18.

(10) FIG. 2 shows in a longitudinal section the axial piston machine from FIG. 1. In this case, the plane of intersection runs through the first pressure control valve 8 and through the first actuating chamber 21 which is associated therewith. The actuating piston 22 is therefore also visible.

(11) Also shown is a cylinder barrel 24, which rotates with the drive shaft 18, and in which are inserted a plurality of circumferentially distributed pistons 25. These are pivotably connected to the swashplate 26. The swashplate 26 is supported on the first housing section 2 and in FIG. 2 is shown in its center zero-stroke position.

(12) For increasing the pivot angle of the swashplate 26 and therefore for increasing the stroke of the pistons 25 in the cylinder barrel 24, the axial piston machine, operated as a pump, for creating a first delivery direction, pressurizes the first actuating chamber 21 with pressurized actuating medium via the first pressure control valve 8, while the pressurized actuating medium of the second actuating chamber (not shown) is released via the second pressure control valve 10 (shown in FIG. 1). To this end, an electric actuator 28 of the first pressure control valve 8 is energized so that this opens a connection from a feed pump 30 via a first feed pressure passage 32 and via a feed pressure port 34 to an actuating pressure port 36. From there, the pressurized actuating medium flows via an actuating pressure passage 38 and via a connecting bore 40 into the first actuating chamber 21.

(13) The construction and the function of the two pressure control valves 8, 10 is explained more precisely with reference to FIG. 4.

(14) Also shown in FIG. 2 is that a cartridge 42 of the pressure control valves 8, 10 is inserted into an installation hole 44 of the first housing section 2. In this case, the installation hole 44 penetrates the first housing section 2 so that an inner end section 46 of the cartridge 42 projects into an interior space 48 of the housing 2, 4. Since the installation hole 44 is at a distance from the inner end section 46 of the cartridge 42, a connection from a tank port T of the pressure control valve 8, 10 to the interior space 48 of the housing 2, 4 is formed there. The tank port T of the pressure control valve 8, 10 is formed in an encompassing manner on the cartridge 42 and arranged adjacent to the inner end section 46 of the cartridge 42. The feed pressure port 34 is arranged adjacent to the actuator 28. The actuating pressure port 36 is arranged between the tank port T and the feed pressure port 34. The feed pressure port 34 and the actuating pressure port 36 are designed as annular pressure chambers between the cartridge 42 and the installation hole 44.

(15) The valve bodies (not shown in FIG. 2) of the pressure control valves 8, 10 can be moved in the respective cartridge 42 and as a result of their parallel distance from each other defined a so-called valve body plane 50 which could also be referred to as a pressure control valve plane. As a result, both valve bodies move along the valve body plane 50. The valve body plane 50 is oriented obliquely to the actuating piston plane 20 and obliquely to the axis 16 of the drive shaft 18 and in this case runs through between the actuating chambers 21 and the cylinder barrel 24. As a result, the cartridge 42 is arranged in directly proximity to the actuating chambers 21. Consequently, the actuating pressure passage 38, which connects the actuating pressure port 36 to the connecting bore 40, can be produced by means of a single short communication bore.

(16) Since a diameter of the connecting bore 40 is larger than a diameter of the actuating pressure passage 38, an oblique position of the actuating pressure passage 38 in relation to the connecting bore 40 is simple to realize in respect to production engineering. Furthermore, after the drilling of the connecting bore 40 and the actuating pressure passage 38 only a seal 51 for closing off the common hole in the wall of the first housing section 2 is required.

(17) The first feed pressure passage 32 is also produced by means of a single oblique bore on a side of the cartridge 42 of the first pressure control valve 8 facing away from the actuating pressure passage 38 and the actuating cylinder 6. This single bore connects a contact face 52 of the first housing section 2, against which butts the second housing section 4, to the feed pressure port 34.

(18) FIG. 3 shows the axial piston machine of the preceding figures in a cross section through the first housing section 2. The plane of intersection (D-D) is drawn in in FIG. 2 and runs through the cylinder barrel 24 and the pistons 25. Also shown are the two cartridges 42 of the pressure control valves 8, 10 (again without the valve bodies guided therein). The plane of intersection runs through the two feed pressure ports 34. The supply of the second pressure control valve 10 with pressurized feed medium is effected from the feed pressure port 34 of the first pressure control valve 8 via a second feed pressure passage 54 which runs parallel to the actuating piston plane 20 (cf. FIG. 2).

(19) FIG. 4 shows one of the two similarly constructed pressure control valves 8, 10. It is designed as a cartridge valve with the cartridge 42. The inner end section 46 of the cartridge 42 is closed off on the end face by a spring plate 56. Starting from there, the tank port T, an O-ring 58, the actuating pressure port 36, a further O-ring 58 and the feed pressure port 34 are arranged on the outer circumference of the cartridge 42. The electric actuator 28 is fastened on the cartridge 42. To be more exact, a pole core 60 is fastened on the cartridge 42, and arranged on its outer side facing away from the cartridge 42 is an armature 62. This is movably accommodated in a pressure tube 64 and together with the armature 60 is encompassed by a solenoid 66.

(20) With energizing of the solenoid 66 via a connector 68, the armature 62 is moved in the direction toward the pole core 60 and via a plunger 69 which is movably accommodated in the pole core 60 therefore forces the valve body 70, designed as a valve piston, to the left in FIG. 4. This takes place against the force of a spring 72 which is arranged in the inner end section 46 of the cartridge 42 and which is supported on the spring plate 56. With energizing of the electric actuator 28, the valve body 70 is displaced from the position which is pretensioned by the spring 72 and shown in FIG. 4 in the direction toward the spring plate 56 so that instead the connection (shown in FIG. 4) from the actuating pressure port 36 to the tank port T is closed, while at the same time a connection from the feed pressure port 34 to the actuating pressure port 36 is opened. To this end, the valve body 70 has a piston collar 74 in the region of the actuating pressure port 36.

(21) In the piston collar 74, provision is made for a bore via which an inner longitudinal bore of the valve body 70 is continuously pressurized by actuating pressure. As a result, a larger end face 76 and a smaller end face 78 of the valve body 70 are also pressurized by actuating pressure. The larger end face 76 is arranged inside the end section 46 of the cartridge 42 and together with the spring 72, which also butts against this end face 76, acts in a direction in which the actuating pressure port 36 is increasingly connected to the tank port T. The smaller end face 78 in comparison is arranged in the region of the connection of the cartridge 72 to the pole core 60 and acts in an opposite direction in which the actuating pressure port 36 is increasingly connected to the feed pressure port 34. For this reason, the valve body 70 is a stepped piston.

(22) In the region of the connection of the cartridge 42 and the pole core 60, provision is made for an outer O-ring 58 which seals the feed pressure port 34 to the outside. Between the outer O-ring 58 and a housing of the actuator 28, provision is made for the flange 14 which has the two illustrated (with reference to FIG. 1) oppositely disposed sockets 80 for screws 12. Via these, the cartridge 42 is retained in the installation hole 44 (cf. FIG. 2).

(23) Disclosed is a hydrostatic axial piston machine with a double-acting actuating cylinder for adjusting the piston displacement, wherein the two actuating chambers of the actuating cylinder are connected to two spatially separated cartridge valves which are inserted obliquely into a wall section of the axial piston machine. The wall section on the one hand forms a wall of the housing of the axial piston machine and on the other hand forms a wall of the actuating cylinder.

LIST OF DESIGNATIONS

(24) 2 First housing section

(25) 4 Second housing section

(26) 6 Actuating cylinder

(27) 8 First pressure control valve

(28) 10 Second pressure control valve

(29) 12 Screw

(30) 14 Flange

(31) 16 Axis

(32) 18 Drive shaft

(33) 20 Actuating piston plane

(34) 21 First actuating chamber

(35) 22 Actuating piston

(36) 24 Cylinder barrel

(37) 25 Piston

(38) 26 Swashplate

(39) 28 Electric actuator

(40) 30 Feed pump

(41) 32 First feed pressure passage

(42) 34 Feed pressure port

(43) 36 Actuating pressure port

(44) 38 Actuating pressure passage

(45) 40 Connecting bore

(46) 42 Cartridge

(47) 44 Installation hole

(48) 46 Inner end section

(49) 48 Interior space

(50) 50 Valve body plane

(51) 51 Seal

(52) 52 Contact face

(53) 54 Second feed pressure passage

(54) 56 Spring plate

(55) 58 O-ring

(56) 60 Pole core

(57) 62 Armature

(58) 64 Pressure tube

(59) 66 Solenoid

(60) 68 Connector

(61) 69 Plunger

(62) 70 Valve body

(63) 72 Spring

(64) 74 Piston collar

(65) 76 Larger end face

(66) 78 Smaller end face

(67) 80 Socket

(68) T Tank pressure/Tank port