WO2014166691A1

WO2014166691A1 - Axial piston machine

Info

Publication number: WO2014166691A1
Application number: PCT/EP2014/054789
Authority: WO
Inventors: Timo Nafz; Frank Scholz
Original assignee: Robert Bosch Gmbh
Priority date: 2013-04-08
Filing date: 2014-03-12
Publication date: 2014-10-16
Also published as: EP2984343A1; DE102013206161A1

Abstract

The invention relates to an axial piston machine having pistons which are guided so as to be movable back and forth in a substantially axial direction in cylinder chambers of a cylinder, and having a pivot cradle (28) which is pivotable about a pivot axis between pivoting endpoints (47, 48), wherein the pivot cradle (28) is pivoted by means of at least one actuating piston which is guided so as to be movable back and forth in the direction of an axis of translation (38). To optimize the axial piston machine, in particular with regard to wear that occurs during the operation of the axial piston machine, the axis of translation (38) for the guidance of the actuating piston is displaced transversely toward an axis of rotation of a cylinder of the axial piston machine.

Description

description

title

axial piston

The invention relates to an axial piston machine with pistons, which are guided in a substantially axial direction in cylinder chambers of a cylinder back and forth, and with a pivoting cradle which is pivotable about a pivot axis between Schwenkendpunkten, wherein the pivoting cradle pivoted by means of at least one actuating piston is, which is guided back and forth in the direction of a translation axis.

State of the art

From US patent US 6,352,017 B1 a hydraulic pump with a swash plate and piston is known, which are guided in a cylinder block movable back and forth, the pistons are coupled via sliders which are slidably abutting the swash plate with the swash plate, said Sliders are biased by an elastic Gleitstückhalter against the swash plate.

Disclosure of the invention

The object of the invention is to optimize an axial piston according to the preamble of claim 1, in particular with regard to a occurring during operation of the axial piston wear.

The object is in an axial piston machine with pistons, which are guided in a substantially axial direction in cylinder chambers of a cylinder back and forth, and with a pivoting cradle which is pivotable about a pivot axis between Schwenkendpunkten, wherein the pivoting cradle by means of at least one actuating piston is pivoted in the direction of a Translational axis is guided to and fro movable, achieved by the fact that the translation axis is displaced transversely to the axis of rotation of a cylinder of the axial piston machine for guiding the actuating piston. As a result, during operation of the axial piston machine, a relative movement between the actuating piston and the pivoting cradle can be reduced in a simple manner. This in turn can be an undesirable Kolbenverkippung be minimized. Furthermore, undesired wear of a sealing element, which may be attached to a piston foot of the adjusting piston, and the piston guide can be reduced. Cross means perpendicular to the axis of rotation of the cylinder.

A preferred embodiment of the axial piston machine is characterized in that the translation axis for guiding the actuating piston is displaced by a part of a transverse offset of the actuating piston to the axis of rotation of the cylinder. According to one aspect of the invention, the translational axis for guiding the actuating piston is not displaced by the total transverse offset, but only by a part of the transverse offset.

Another preferred embodiment of the axial piston machine is characterized in that the translation axis for guiding the actuating piston is displaced by half the transverse offset of the actuating piston to the axis of rotation of the cylinder. With this transverse displacement of the translational axis, the best results were achieved in investigations carried out in the context of the present invention. The above-mentioned object is alternatively or additionally solved in an axial piston machine described above in that the translation axis is not parallel to the axis of rotation of the cylinder of the axial piston machine for guiding the actuating piston, but inclined at an inclination angle to the axis of rotation or to a parallel axis of rotation. This measure with regard to the translation axis can be combined with the displacement of the translation axis described above. The measures described can also be applied individually.

Another preferred embodiment of the axial piston machine is characterized in that the inclined translation axis is defined by an upper

Schwenkendpunkt the pivoting cradle runs. The upper pivot end point of Pivoting cradle corresponds, for example, the deflection of a pivot point of the actuating piston on the pivoting cradle when the pivoting cradle has been pivoted upwards by a maximum pivoting angle from a central position or basic position.

A further preferred embodiment of the axial piston machine is characterized in that the angle of inclination of the translation axis corresponds to a portion of an offset angle between a pivot circular chord passing through two pivot end points of the pivot cradle and the axis of rotation or parallel to the axis of rotation. According to a further aspect of the invention, the translation axis is not tilted by the total offset angle, but only by a part of the offset angle between the swing circle chord and the axis of rotation or the parallels to the axis of rotation.

A further preferred embodiment of the axial piston machine is characterized in that the angle of inclination of the translation axis corresponds to half of the offset angle. Thus, the best results were achieved in investigations carried out in the context of the present invention.

Another preferred embodiment of the axial piston machine is characterized in that the adjusting piston is articulated to the pivoting cradle. The adjusting piston may, for example, have a ball head, with which the adjusting piston is articulated directly to the pivoting cradle.

A further preferred embodiment of the axial piston machine is characterized in that the adjusting piston is coupled to the pivoting cradle with the interposition of a sliding device, which bears slidably on the pivoting cradle. The actuator piston is thus not directly hinged to the pivoting cradle, but only indirectly coupled with this.

The invention further relates to a guide device for a previously described axial piston machine. The guide device is represented, for example, by a housing with a corresponding housing bore. An essential feature of the guide device according to the invention, which separately is tradable represents the translation axis of the actuator piston, which is moved and / or inclined according to an essential aspect of the invention.

The invention further relates to a mobile or stationary hydraulic drive with an axial piston machine described above. The axial piston machine in the hydraulic drive is also referred to as hydrostat. The mobile hydraulic drive is preferably part of a Hydraulikhybndantriebsstrangs, in particular of a motor vehicle.

Further advantages, features and details of the invention will become apparent from the following description in which, with reference to the drawings, various embodiments are described in detail.

Short description of the drawing

Show it:

1 shows a Hydrostaten in Axialkolbenbauart with a distributor plate and a connection plate in longitudinal section;

Figure 2 shows a detail of Figure 1 according to an embodiment of the invention;

Figure 3 is a pivoting cradle solely for illustrating the invention and

4 shows an enlarged detail of Figure 3.

Description of the embodiments

1 shows a hydrostat 1 in axial piston design is shown in longitudinal section. The hydrostat 1 can also be referred to as axial piston machine. The axial piston machine 1 comprises a housing 2 with a cylinder 3 and a drive shaft 4. The axial piston machine 1 can be operated in an open circuit or in a closed circuit. In the open circuit, a hydraulic medium, such as hydraulic oil, which is also referred to as pressure fluid, flows from a tank to the axial piston machine 1 and is conveyed from there via a valve device to a consumer. From the consumer, the hydraulic medium flows back through the valve device to the tank. In a closed circuit, the hydraulic medium flows from the axial piston machine to the consumer and from there directly back to the axial piston machine 1. There is a high pressure side and a low pressure side, which can change depending on the load.

When the axial piston engine is mechanically driven via the drive shaft 4, then the axial piston engine operates as an axial piston pump. When the axial piston engine is hydraulically driven via the cylinder 3, the axial piston engine operates as an axial piston engine. The axial piston machine 1 can only be operated as a motor or only as a pump. The axial piston machine 1 can in principle but also be operated alternately both as a pump and as a motor. The hydrostat 1 comprises a plurality of pistons 5, which are arranged axially relative to the drive shaft 4. Axial means in the direction or parallel to a rotation axis of the drive shaft 4. By a pivoting cradle 8, which is also referred to as a swash plate, a funded by the axial piston volume flow can be adjusted continuously. Therefore, the hydrostat 1 is referred to with the pivoting cradle 8 as a variable displacement pump.

In pump operation, the drive shaft 4 is driven by a (not shown) drive motor with torque and speed. About the drive shaft 4, which is also referred to as the drive shaft, the cylinder 3, for example, via a toothing, taken and rotated. At each revolution, the piston 5 in cylinder bores of the cylinder 3 perform a stroke whose size is dependent on the inclination of the pivoting cradle 8.

Between the pivoting cradle 8 and the piston 5 sliding devices 10 are arranged, which are also referred to as piston shoes or shoes 10. The sliding shoes or piston shoes 10 are connected to the piston 5 by a Retraction plate 12 is held and guided on a sliding surface of the pivoting cradle 8.

Due to the inclination of the pivoting cradle 8, each piston 5 moves during one revolution over a lower and a top dead center back to its original position. In this case, by control geometries in a control plate or distributor plate 13 a pressure fluid corresponding to the stroke volume and discharged. The distributor plate 13 is arranged between the cylinder 3 and a connection plate or adapter plate 14.

On a suction side, in pump operation, pressure fluid flows into an enlarging piston chamber. At the same time, the pressure fluid is pressed by the piston 5 from the cylinder chamber into a connected hydraulic system on a high pressure side.

The swivel angle of the swivel cradle 8 is infinitely adjustable. By adjusting the pivot angle of the pivoting cradle 8, the piston stroke and thus the displacement volume of the axial piston machine 1. The adjustment of the pivot angle is hydraulically via a control piston 15. The pivoting cradle 8 is easily stored in pivot bearings and is supported by a

Opposite piston 16 held in equilibrium. At an enlargement of the

Swivel angle increases the displacement volume of the axial piston machine 1, with a reduction, this decreases accordingly. FIG. 2 shows a section of a similar axial piston machine 21 as in FIG

1 shown. The axial piston machine 21 comprises a housing 22, in which a drive shaft 24 is rotatably arranged about an axis of rotation not designated in detail. An actuating piston 26 is articulated via a ball head 30 to a pivoting cradle 28. The adjusting piston 26 has at its end facing away from the ball head 30 a piston foot 32, which is formed spherically. For sealing, a sealing element 35 is arranged on the piston foot 32. The sealing element 35 on the piston foot 32 of the actuating piston 26 serves to seal a positioning space 36 in the housing 22. About a signal pressure in the control room 36, a pivoting of the pivoting cradle 28 can be effected about a pivot axis in a simple manner. When pivoting the pivoting cradle 28, a pivot point between the control piston 26 and the pivoting cradle 28 moves on a circular arc, which is indicated by a double arrow 37. By a further double arrow 38, a translational movement of the actuating piston 26 is indicated. By a further double arrow 39 is indicated that the translational movement 38 of the actuating piston 26 is superimposed by a tilt.

The kinematics of the actuating piston 26 is determined by the point of articulation and by the guidance of the piston foot 32 in the housing 22 or in a corresponding guide bushing. The object of the present invention is to minimize the piston tilt 39 of the actuating piston 26.

In Figure 3, the pivoting cradle 28 is shown alone. By a dashed line 40, a rotation axis of the drive shaft of the axial piston machine is indicated. The pivoting cradle 28 is pivotable about a pivot axis 41, which extends perpendicular to the plane of the figure 3.

A pivoting circle of the pivoting cradle 28 is indicated by a dashed circular arc 43. By double arrows 44 and 45 pivoting angles are indicated by which the pivoting cradle 28 from a middle position shown in Figure 3 or basic position up or down counterclockwise or clockwise is pivotable.

The pivoting cradle 28 is coupled in an articulation point 46 with an actuating piston (not shown in FIG. 3). In a pivoting movement in the counterclockwise direction in the direction of the double arrow 44, the pivot point 46 moves up to an upper pivot end point 47. When pivoting in the clockwise direction in the direction of the double arrow 45, the pivot point 46 moves to a lower pivot end point 48th

In Figure 4, a section of Figure 3 is shown enlarged. In the enlarged section, it can be seen that a dashed line 50 extends parallel to the axis of rotation of the drive shaft of the axial piston machine through the upper pivot end point 47. A dashed line 51 extends through the two Pivot end points 47 and 48. The dashed line 51 represents a chord of the pivoting circle 43.

By a rectangle 53, a piston guide or translation axis of the actuating piston (26 in Figure 2) is indicated. By a double arrow 54, an angle between the chord 51 and the dashed line 50 is indicated, which extends parallel to the axis of rotation of the drive shaft of the axial piston machine.

With a complete pivoting of the pivoting cradle 28 between the two pivot end points 47 and 48 occurs, based on the pivoting circle

43, radial offset, which is indicated in Figure 4 by a double arrow 55. In the present invention, it is a matter of minimizing the radial offset 55, which is also referred to as a transverse set. A rectangle 56 indicates in FIG. 4 that the guide or translation axis of the actuating piston is displaced into the middle of the radial offset 55. By this measure it is achieved that the actuating piston tilts in both directions by the same angle. By a rectangle 59 is indicated that the piston guide or translation axis of the actuating piston is tilted in accordance with a further aspect of the invention by the angle 54. By this measure, the tilting of the actuating piston can be reduced by the double arrow 55 to a double arrow 58. By a rectangle 60 is indicated that the two previously described

Measures can be combined. By the rectangle 60 is indicated that the piston guide or translation axis is inclined by the angle 54 and moved in the middle of the double arrow 58. The above-described measures for minimizing the actuator piston tilting can also be applied to actuating pistons with sliding shoes, as shown in FIG. However, in the adjusting piston with sliding shoes, not the tilting but the sliding path of the actuating piston or the sliding shoes is minimized relative to the pivoting cradle. As a result, as with the minimization of the tilt angle, the wear can be minimized.

Claims

claims

1 . Axial piston machine with pistons (5), which are guided in a substantially axial direction in cylinder chambers of a cylinder (3) movable back and forth, and with a pivoting cradle (8; 28), which about a pivot axis (41) between pivot end points (47, 48) is pivotable, wherein the

Pivoting cradle (8; 28) by means of at least one actuating piston (16; 26) which is guided in the direction of a translation axis (38) to and fro, characterized in that the translation axis (38) for guiding the actuating piston (26 ) is displaced transversely to a rotation axis (40) of a cylinder (3) of the axial piston machine (1, 21).

2. Axial piston machine according to claim 1, characterized in that the translation axis (38) for guiding the actuating piston (26) is displaced by a part of a transverse offset (55) of the actuating piston (26) to the axis of rotation (40) of the cylinder (3) ,

3. axial piston machine according to claim 2, characterized in that the translation axis (38) for guiding the actuating piston (26) by half of the transverse offset (55) of the actuating piston (26) to the axis of rotation (40) of the cylinder (3) is displaced ,

4. Axial piston machine according to the preamble of claim 1, in particular according to one of the preceding claims, characterized in that the translation axis (38) for guiding the actuating piston (26) not parallel to the axis of rotation (40) of the cylinder (3) of the axial piston machine (1; 21) is arranged, but inclined at an inclination angle to the rotation axis (40) or to a parallel (50) of the rotation axis.

5. Axial piston machine according to claim 4, characterized in that the inclined translation axis extends through an upper pivot end point (47) of the pivoting cradle. An axial piston machine according to claim 4 or 5, characterized in that the angle of inclination of the translation axis is a part of an offset angle (54) between a pivoting circular chord (51) passing through two pivot end points (47,48) of the pivoting cradle (28) and the pivoting axis (40) ) or a parallel (50) to the rotation axis (40) corresponds.

Axial piston machine according to claim 6, characterized in that the angle of inclination of the translation axis corresponds to half of the offset angle (54).

Axial piston machine according to one of the preceding claims, characterized in that the adjusting piston (26) is articulated to the pivoting cradle (28).

Axial piston machine according to one of claims 1 to 8, characterized in that the adjusting piston (16) with the interposition of a sliding device (10) which is slidably applied to the pivoting cradle (8), with the

Pivoting cradle (8) is coupled.

0. Guide device for an axial piston machine (1, 21) according to one of the preceding claims.