Hydrostatic axial piston machine

Abstract

A hydrostatic axial piston machine has a housing. In the housing of the hydrostatic axial piston machine, an actuating pressure cylinder is formed at an angle to the drive shaft. A control valve is inserted into the actuating pressure cylinder in a cartridge type of design. In order to enable maximum movement of an actuating piston in the direction toward the control valve, the cartridge is of shortened design. To this end, an actuating pressure port, which is arranged between a high-pressure port and a low-pressure port, and an actuating pressure passage are arranged completely inside the cartridge.

Claims

1. A hydrostatic axial piston machine comprising: a swashplate; an actuating piston coupled to the swashplate, the actuating piston configured to be displaced in an actuating cylinder and configured to adjust an inclination of the swashplate, wherein: an actuating pressure chamber, which is arranged in the actuating cylinder, is delimited by a cartridge of a control valve which is inserted into the actuating cylinder, an actuating pressure port of the control valve is arranged between a high-pressure port and a low-pressure port of the control valve, an actuating pressure passage extends from the actuating pressure port to the actuating pressure chamber, and the actuating pressure passage is arranged inside the cartridge.

2. The axial piston machine according to claim 1, wherein: the low-pressure port is arranged in or on a region of the cartridge which is adjacent to the actuating pressure chamber, and the high-pressure port is arranged in or on a region of the cartridge which is adjacent to a solenoid.

3. The axial piston machine according to claim 1, wherein the actuating pressure passage is a longitudinal bore in a spool of the control valve.

4. The axial piston machine according to claim 3, wherein: a feedback spring is mounted between the actuating piston and an end section of the spool, and the feedback spring is arranged at least in a certain section in an interior space of the actuating piston.

5. The axial piston machine according to claim 4, wherein the feedback spring, at least in a relaxed state, is longer than the interior space of the actuating piston.

6. The axial piston machine according to claim 4, wherein the end section of the spool and a spring plate, which is mounted between the end section of the spool and the feedback spring, are configured to be inserted at least in a certain section into the interior of the actuating piston.

7. The axial piston machine according to claim 6, wherein the spring plate is configured such that the feedback spring overlaps the end section of the spool on an outside.

8. The axial piston machine according to claim 6, wherein the spring plate and the end section of the spool have circular cylindrical abutment sections with each other.

9. The axial piston machine according to claim 6, wherein the spring plate on its side orientated toward the spool has an inner chamfer.

10. The axial piston machine according to claim 6, wherein an end face of the cartridge facing the spring plate has an inner collar.

11. The axial piston machine according to claim 3, wherein: the actuating pressure port is an actuating pressure annulus, and/or wherein the high-pressure port is a high-pressure annulus, and/or wherein the low-pressure port is a low-pressure annulus, wherein the high-pressure annulus and the low-pressure annulus are arranged on an outer circumference of the cartridge, and/or wherein the operating pressure annulus is formed by a neck of the spool.

12. The axial piston machine according to claim 11, wherein the neck is connected via a restrictor to the longitudinal bore.

13. The axial piston machine according to claim 1, wherein the axial piston machine is a fan motor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings

(2) FIG. 1 shows in a longitudinal section an axial piston machine according to the disclosure according to the exemplary embodiment, and

(3) FIG. 2 shows in an enlargement a detail of the axial piston machine from FIG. 1.

DETAILED DESCRIPTION

(4) FIG. 1 shows in a longitudinal section the axial piston machine according to the disclosure with its housing 1 in which is mounted a drive shaft 2, on the outer circumference of which a cylinder drum 4 is arranged in a rotation-resistant manner. In the cylinder drum 4, pistons 6 which are distributed on the circumference are axially guided in respective cylinders 8. Formed on the end sections of the pistons 6 which project from the cylinders 8 are piston feet, on which are pivotably attached piston shoes 10 which are guided in a sliding manner on a swashplate 12 which is set at an angle to the drive shaft 2.

(5) When the cylinder drum 4 revolves, the pistons 6 are moved out of the cylinders 8 and in again in dependence of the inclined position of the swashplate 12. Therefore, in the case of an axial piston motor, for example, the swallowing volume per revolution and therefore the rotational speed of the drive shaft 2, serving as an output shaft, can be adjusted. For controlling the inclined position of the swashplate 12, an actuating piston 16, which is guided in an actuating cylinder 14, is coupled via a ball joint 18 to the swashplate on one side.

(6) According to the disclosure, the swashplate 12 can completely pivot through from +100% to 100%. FIG. 1 shows the 100% position of the swashplate 12, in which the actuating piston 16 is retracted into the actuating cylinder 14 to its maximal (furthest distance). In order to enable this, a control valve 20, which is also screwed into the actuating cylinder 14, is of shortened design in its overall length.

(7) FIG. 2 shows in an enlargement a detail of the axial piston machine according to the disclosure. Shown here are the actuating cylinder 14 with the actuating piston 16 guided therein, which actuating piston is also in its maximum retracted position shown in FIG. 2, as a result of which the pivoting angle of 100% is achieved. In this case, the actuating piston 16, on account of its slightly inclined position in the actuating cylinder 14 does not butt by its full extent against an end face of a cartridge 22 of the control valve 20 which is screwed into the actuating cylinder 14.

(8) In the position shown in FIG. 2, an actuating pressure chamber 24 is reduced to an interior space of the actuating piston 16 in which a control spring or feedback spring 26 and a spring plate 28 are also accommodated. The spring plate 28 is of hat-shaped design, wherein the feedback spring 26 extends in a certain section on its outer circumference and is supported there on an edge. Formed on the inner circumference of the spring plate 28, together with an end section of a valve spool 30 which projects into the actuating pressure chamber 24, are circular cylindrical abutment sections 32. This serves for the shortening of the installation space of the arrangement and for the axial stability of the spring plate 28 in relation to the valve spool 30 and of the feedback spring 26 in relation to the two parts 28, 30.

(9) On one side, the swashplate 12, via the actuating piston 16, the feedback spring 26 and the spring plate 28, exerts a distance-dependent feedback force upon the spool 30 of the control valve 20. On the other side, an electric solenoid acts on the valve spool 30, which solenoid can displace the valve spool 30 from its center closed position shown in FIG. 2 either into a first directed direction (to the left in FIG. 2), in which a tank port or low-pressure port 36 is connected to the actuating pressure chamber 24, or the solenoid 34 enables a movement of the valve spool 30 in an opposite directed direction (to the right in FIG. 2) in which a high-pressure port 38 is connected to the actuating pressure chamber 24. Both ports 36, 38 are designed as annular grooves on the outer circumference of the cartridge 22 and have respective radial, for example star-shaped, passages.

(10) An actuating pressure port 40 is formed by a neck of the valve spool 30 which is delimited by two encompassing metering edges, wherein the one metering edge interacts with the radial passages of the low-pressure port 36, whereas the other metering edge interacts with the radial passages of the high-pressure port 38.

(11) Arranged radially in the neck, which forms the actuating pressure port 40, is a comparatively narrow passage which forms a restrictor 42. The restrictor 42, via an actuating pressure passage 44 which is formed inside the valve spool 30 as a concentric longitudinal bore, is connected to the actuating pressure chamber 24. Therefore, the connection of the actuating pressure port 40 to the actuating pressure chamber 24 by the shortest path via the restrictor 42 and the actuating pressure passage 44 is arranged inside the cartridge 22, to be more precise inside the valve spool 30.

(12) Since the actuating pressure port 40 scarcely requires axial length, the cartridge 22 according to the disclosure is comparatively short and therefore extends in the direction of the swashplate 12 only to the extent that the actuating piston 16 in its abutment position shown in FIG. 2 enables a pivoting angle of 100% of the swashplate 12.

(13) The assembly of the arrangement shown in FIG. 2 is facilitated by the feedback spring 26 being longer in the relaxed state than the interior space of the actuating piston 16.

(14) Formed on the inner circumference of the spring plate 28 is a chamfer 46 which facilitates insertion of the end section of the valve spool 30 into the spring plate 26.

(15) Formed on the end face of the cartridge 22 facing the actuating piston 16, in direct proximity to the valve spool 30, is an inner collar 48 via which the spring plate 28 can be centered on account of its chamfer 46.

(16) Disclosed is a hydrostatic axial piston machine, in the housing of which is formed, at an angle to the drive shaft, an actuating pressure cylinder into which a control valve is inserted in a cartridge type of design. In order to enable maximum movement of an actuating piston in the direction toward the control valve, the cartridge is of shortened design. To this end, an actuating pressure port, which is arranged between a high-pressure port and a low-pressure port, and an actuating pressure passage are arranged completely inside the cartridge.

LIST OF DESIGNATIONS

(17) 1 Housing 2 Drive shaft 4 Cylinder drum 6 Piston 8 Cylinder 10 Piston shoe 12 Swashplate 14 Actuating cylinder 16 Actuating piston 18 Ball joint 20 Control valve 22 Cartridge 24 Actuating pressure chamber 26 Feedback spring 28 Spring plate 30 Valve spool 32 Circular cylindrical abutment sections 34 Solenoid 36 Low-pressure port 38 High-pressure port 40 Actuating pressure port 42 Restrictor 44 Actuating pressure passage/longitudinal bore 46 Chamfer 48 Inner collar