The invention concerns a hydraulic module of the type defined in more detail in the preamble of Claim 1.

As disclosed in DE 10 2006 025 347 B3, hydraulic modules of the type concerned, in particular for hydrostatic-mechanical transmissions, comprise integrated inclined-axis drive systems in each case comprising a cylinder block with displacement elements that can move therein, which are mounted so that they can pivot on axis-parallel shafts, such that the cylinder blocks of the two inclined-axis drive systems are mounted with different pivoting angles in a common yoke and, to adjust the volume flow, they can be pivoted necessarily conjointly with the yoke by a servo system.

In DE 10 2006 025 347 B3 the servo adjustment system consists of two servo pistons that act upon the yoke. Exact adjustment of the yoke, in particular exact feedback for adjustment purposes, is difficult because of the tolerances involved.

The purpose of the present invention is to provide a hydraulic module characterized by a simple structure, which can be controlled accurately.

This objective is achieved by a hydraulic module of the type concerned which also embodies the characterizing features specified in the principal claim.

According to the invention, the hydraulic module comprises a yoke mounted to pivot about a pivot axis. By pivoting the yoke about the pivot axis the stroke volume of the inclined-axis drive systems can be varied. The yoke has a pin positioned between the two bearings carrying the yoke. The pin is connected integrally with the yoke or can be made as a separate component connected to the yoke in a fixed position.

The pin is in active connection with a piston so that translational movement of the piston moves the pin in such manner that the yoke is caused to pivot about its pivot axis.

In a further development of the invention the piston has an opening in which the pin engages. The end of the pin that engages in the piston is preferably ball-shaped, since this minimizes the frictional resistance between the piston and the pin. The pin is preferably positioned between the two inclined-axis drive systems, and the yoke can comprise a plate between the two inclined-axis drive systems which holds the pin.

The longitudinal axis of the piston is arranged perpendicularly to the pivot axis of the yoke, with the piston positioned between the bearings of the inclined-axis drive systems. This makes it possible, in a direct coaxial extension of the piston, to obtain information in a simple manner about the momentary displacement angle of the yoke and to adjust the yoke with precision by means of a control device.

In a further development of the invention, the hydraulic module comprises a plate, which on the one hand holds the bearing of the inclined-axis drive system and on the other hand has a bore for the piston. Furthermore, the bearings of the yoke are permanently connected to the plate.

Other features emerge from the description of the figures, which show:

Fig. 1: Three-dimensional representation of part of the hydraulic module, and

Fig. 2: Section through the three-dimensional representation shown in Fig. 1

Fig. 1:

A yoke 1 is mounted to pivot on a first bearing 2 and a second bearing 3, about a pivot axis 4. In the yoke 1 are arranged inclined-axis drive systems as described in DE 10 2006 025 347 B3. Between the inclined-axis drive systems is a pin 5 that engages in a piston 6. The piston 6 is held in a plate 7 which carries the bearing 8 of the inclined-axis drive systems and is connected to the first bearing 2 and the second bearing 3.

Fig. 2:

The yoke 1 comprises a plate 9, which is arranged between the inclined-axis drive systems and into which the pin 5 is screwed. The piston 6 has an opening 10 in which the ball-shaped end 11 of the pin 5 engages. Together with the plate 7 the piston 6 forms a first space 12 and a second space 13. When the first space 12 is pressurized by a pressure medium, the piston 6 moves in a first movement direction whereby, by means of the pin 5, the yoke 1 is pivoted in a first pivoting direction. When the second space 13 is pressurized, the piston 5 moves in a second movement direction such that the yoke 1 is pivoted by the pin 5 in a second pivoting direction. Between the first space 12 and the second space 13 the piston 6 has a groove 14, by which pressure medium leakage is drained away to the opening 10 to ensure precise working of the piston. At its end opposite the space 12 the piston has connection means 15 by virtue of which feedback or position determination of the piston 6 in hydraulic or electronic form is enabled.

The invention provides a hydraulic module which enables exact control of the stroke volume without taking up additional structural space.

Indexes

1 Yoke

2 First bearing

3 Second bearing

4 Pivot axis

5 Pin

6 Piston

7 Plate

8 Bearing

9 Plate

10 Opening

11 Ball-shaped end

12 First space

13 Second space

14 Groove

15 Connection means

Claims

1. Hydraulic module with two inclined-axis drive systems integrated in the
hydraulic module, each of which comprises a cylinder block mounted in a common yoke
(1), the yoke being mounted to pivot in bearings (2, 3) about a pivot axis (4) in order to
adjust the stroke volume, characterized in that between the bearings (2, 3) the common
yoke (1) has a pin (5) which is in active engagement with a piston (6) so that when the
piston (6) moves in translation, the yoke (1) is pivoted about its pivot axis (4).

2. Hydraulic module according to Claim 1, characterized in that the piston (6) has an opening (10) in which the pin (5) engages.

3. Hydraulic module according to Claim 1, characterized in that the piston (6) and pin (5) are arranged between the inclined-axis drive systems.

4. Hydraulic module according to Claim 1, characterized in that between the inclined-axis drive systems the yoke (1) has a plate (9), which is connected top the pin (5).

5. Hydraulic module according to Claim 4, characterized in that the plate (9) is arranged parallel to the piston (6).

6. Hydraulic module according to Claim 1, characterized in that the pin (5) has a ball-shaped end (11) which engages in the piston.

7. Hydraulic module according to Claim 1, characterized in that the pin (5) is arranged perpendicularly to the pivot axis (4) of the yoke (1).

8. Hydraulic module according to Claim 1, characterized in that the piston (6) is arranged in a plate (7) in which the bearing (8) of the inclined-axis drive systems is located.

9. Hydraulic module according to Claim 8, characterized in that the bearings (2, 3) of the yoke (1) are connected to the plate (7).