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Hydrostatic axial piston machine

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Hydrostatic axial piston machine


A hydrostatic axial piston machine of swash plate design includes a pivot cradle configured to be pivoted by a regulating valve. The movement of the pivot cradle is fed back to the regulating valve via a return spring. The return spring is attached to the pivot cradle in the region between its end section on the regulating-valve side and an end section which is remote from the regulating valve.

Browse recent Robert Bosch Gmbh patents - Stuttgart, DE
USPTO Applicaton #: #20140033911 - Class: 91499 (USPTO) -
Motors: Expansible Chamber Type > Three Or More Cylinders Arranged In Parallel Radial Or Conical Relationship With Rotary Transmission Axis >Cylinders Parallel To Rotation Axis

Inventors: Ruslan Rudik, Timo Nafz

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The Patent Description & Claims data below is from USPTO Patent Application 20140033911, Hydrostatic axial piston machine.

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This application claims priority under 35 U.S.C. §119 to patent application no. DE 10 2012 015 503.4, filed on Aug. 4, 2012 in Germany, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

The disclosure relates to a hydrostatic axial piston machine of swash plate design.

An axial piston machine of this type is disclosed, for example, in DE 10 2008 038 435 A1. In said hydrostatic machines, the delivery/displacement volume can be adjusted by pivoting of a pivot cradle, against which a multiplicity of pistons bear which are guided in a cylinder barrel. In the known embodiment, the pivoting of the pivot cradle takes place via a countercylinder and an actuating cylinder, the countercylinder loading the pivot cradle in one direction and the actuating cylinder loading it in the opposite direction. A counterpiston of the countercylinder is loaded with the pump pressure in the usual way, whereas an actuating piston of the actuating cylinder is loaded with control oil via a regulating valve. A valve slide of the regulating valve can be adjusted counter to the force of a return spring, the prestress of said return spring depending on the pivoting angle of the pivot cradle. The valve slide of the regulating valve is situated in its regulating/basic position when the actuating force which acts electrically or electrohydraulically on the valve slide is in equilibrium with the force of the return spring; the pivot cradle is then set to a pivoting angle which is proportional to the actuating force which acts at the regulating valve.

In the known axial piston machine, the return spring is coupled via a linkage to the counterpiston, the regulating valve and the return spring being attached to the housing of the axial piston machine and the linkage protruding out of the housing of the axial piston machine into the attached valve housing.

The attached valve housing with the return spring requires a considerable amount of installation space; in addition, the construction of the housing of the axial piston machine is relatively complex, since the linkage has to be guided through it in a suitable way.

Under the type designation A4CSG, Bosch Rexroth AG presents an axial piston machine with electro-proportional adjustment, the adjustment mechanism of which is described in detail in DE 100 63 526 C1. In this solution, the regulating valve and the countercylinder are likewise coupled mechanically via a driver and are arranged transversely with respect to the axis of a drive shaft which is connected to the cylinder barrel, and are attached to the housing of the axial piston machine. This variant exhibits the same disadvantage as the above-described prior art: as a result of the attachment of the housings for the regulating valve and for the return spring, the radial dimensions of the axial piston machine are comparatively great. In contrast, the disclosure is based on the object of providing a compact hydrostatic axial piston machine.

SUMMARY

This object is achieved by a hydrostatic axial piston machine having the features of the disclosure.

Advantageous developments of the disclosure are the subject matter of the subclaims.

The axial piston machine according to the disclosure is configured with an electro-proportional adjustment of the pivoting angle of a pivot cradle, a counterpiston of a countercylinder and/or an actuating piston of an actuating cylinder acting on said pivot cradle. Said actuating piston can be actuated by means of a proportionally adjustable regulating valve, the valve slide of which is loaded via a return spring with a returning force which is dependent on the pivoting angle. A multiplicity of pistons which are guided in the cylinder barrel which is connected operatively to a drive shaft are supported on the pivot cradle. According to the disclosure, in the region between its end section on the regulating-valve side and the end section which is remote from the regulating valve, the return spring is attached on the pivot cradle. As a result of this geometry, the overall length of the axial piston machine can be reduced considerably, since the attachment usually takes place on the other side of the return spring.

In one preferred exemplary embodiment of the disclosure, the regulating spring is attached indirectly to the pivot cradle.

The regulating spring can be supported, for example, on a spring sleeve, the pivot cradle then being connected to the spring sleeve in a non-positive or positively locking manner by way of a driver.

In an alternative solution, the spring sleeve can be supported on the housing side via a bearing spring.

A very compact solution is obtained if the bearing spring is arranged coaxially with respect to the return spring, it being possible for both springs to lie behind one another.

In order to make sufficient support possible, the spring force of the bearing spring is preferably selected to be greater than the spring force of the return spring.

The overall length of the axial piston machine can be reduced further if the sleeve which supports the return spring has, on the bottom side, a receptacle for an end section of the bearing spring, with the result that both springs overlap one another in sections.

In one exemplary embodiment of the disclosure, the return spring is arranged laterally offset with respect to the actuating cylinder or with respect to the countercylinder.

The orientation of the structural elements can be selected in such a way that the countercylinder, the actuating cylinder and the return spring lie parallel to the drive-device axis.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following text, preferred exemplary embodiments of the disclosure will be explained in greater detail using diagrammatic drawings, in which:

FIG. 1 shows a longitudinal section through a hydrostatic axial piston machine according to the disclosure of swash plate design,

FIG. 2 shows a diagrammatic side view of the open housing of the axial piston machine according to FIG. 1,

FIG. 3 shows an outline sketch of the construction of an adjusting device of a pivot cradle of the axial piston machine according to FIGS. 1 and 2, and

FIG. 4 shows a variant of an adjusting device for a pivot cradle of the axial piston machine.



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stats Patent Info
Application #
US 20140033911 A1
Publish Date
02/06/2014
Document #
13958420
File Date
08/02/2013
USPTO Class
91499
Other USPTO Classes
International Class
01B3/00
Drawings
4



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