Hydraulic unit

Abstract

A hydraulic unit includes an assembly with a hydrostatic positive displacement pump and an electric motor. The positive displacement pump includes a driving shaft configured to be driven by the electric motor. The hydraulic unit also includes an inert mass on which the assembly is rigidly mounted so as to minimize vibration of the assembly and reduce noise emission from the assembly.

Claims

1. A hydraulic unit, comprising: an assembly that includes a hydrostatic positive displacement pump and an electric motor having a motor shaft, the positive displacement pump including a pump shaft fixedly connected to the motor shaft such that the pump shaft is driven in rotation by the electric motor; and an inert mass on which the assembly is rigidly mounted, wherein the positive displacement pump is rigidly mounted on the inert mass and the electric motor is supported by the positive displacement pump, and wherein the inert mass is formed as a solid body of polymer concrete.

2. The hydraulic unit according to claim 1, wherein the positive displacement pump has a pump housing with (i) a first front side on which the pump shaft is accessible and configured to couple with the motor shaft of the electric motor and (ii) a second front side, which is opposite the first front side, on which the pump housing is rigidly connected to the inert mass.

3. The hydraulic unit according to claim 2, wherein the pump housing has a mounting flange on the second front side, the mounting flange directly rigidly mounted on the inert mass.

4. The hydraulic unit according to claim 2, wherein the pump housing is rigidly mounted on the second front side on the inert mass via an intermediate plate.

5. The hydraulic unit according to claim 1, wherein the positive displacement pump is mounted in a vertical direction on the inert mass.

6. The hydraulic unit according to claim 1, wherein the positive displacement pump and the electric motor are mounted on a pump support that is rigidly mounted on the inert mass.

7. The hydraulic unit according to claim 1, wherein the positive displacement pump has a pump housing that is rigidly connected to a housing of the electric motor.

8. The hydraulic unit according claim 7, wherein the pump housing and the housing of the electric motor are rigidly connected to one another via an intermediate plate.

9. The hydraulic unit according to claim 1, wherein the pump shaft and the motor shaft of the electric motor are fitted into one another.

10. The hydraulic unit according to claim 1, wherein the positive displacement pump is rigidly mounted on the inert mass without coupling housings having coupling or elastic intermediate layers.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) An exemplary embodiment of a hydraulic unit according to the disclosure, in which the pump shaft and the motor shaft are directly fitted into one another, is illustrated in the drawing. The disclosure is now explained in more detail with reference to this drawing.

DETAILED DESCRIPTION

(2) In accordance with the drawing, a hydrostatic positive displacement pump 5, for example an axial piston pump or a gear pump, has a pump housing 6 and a pump shaft 7 rotatably mounted in the pump housing. The pump housing 6 has a first front side 8 and a second front side 9 in the direction of the pump shaft 7. The positive displacement pump 5 is fixedly connected to an intermediate plate 11 on this front side 9 and mounted on an inert mass 12 via the intermediate plate 11. The inert mass 12 is a solid body and consists in particular of polymer concrete, concrete or a metallic structure.

(3) The positive displacement pump 5 is fixedly connected to an intermediate plate 13 on the front side 8, on which an electric motor 15 formed in particular as a servomotor or asynchronous motor is mounted with its housing 14. Overall, a first intermediate plate, a positive displacement pump, a second intermediate plate and an electric motor are therefore arranged in the vertical direction one above another on the inert mass 12 as main body. The intermediate plate 11 is screwed to the positive displacement pump 5 and outside of its contour to the inert mass 12. The intermediate plate 13 is likewise screwed to the positive displacement pump 5 and outside of its contour to the electric motor 15. The intermediate plates are a type of adapter, which facilitate screwing of the parts to each other, even when the screw holes of the parts have different distances from a central axis of the hydraulic unit.

(4) If the positive displacement pump 5 is formed with mounting flanges which match the screw holes of the other parts, the intermediate plates can be dispensed with. This then results in a particularly low overall length of a hydraulic unit according to the disclosure.

(5) As a result of the inert mass, the natural vibrations of the assembly comprising the positive displacement pump 5 and the electric motor 15 are reduced. Vibrations thus only occur to a limited extent and are passively damped.

(6) In the highly schematic illustration according to the drawing, outside of the pump shaft 7 of the positive displacement pump 10, a motor shaft 16 of the electric motor 15 can also be identified. A recess 17, into which the pump shaft 7 is immersed, is introduced into the motor shaft 16 from its front side facing the pump shaft 7. Within the recess 17, the pump shaft 7 and the motor shaft 16 are coupled to one another in a manner secured against rotation, for example by an internal toothing of the motor shaft in the recess and an external toothing of the pump shaft or using a fitting groove and a feather key. The direct coupling of the pump shaft and motor shaft without a shaft coupling as an additional component contributes to the hydraulic unit being able to be constructed short in the axial direction, i.e. in the direction of the axes of the shafts 7 and 16. The tendency of the assembly to vibrate is reduced as a result of a short overall length.

(7) Overall, a hydraulic unit is thus disclosed, which emits little noise, has a compact design and is constructed in a straightforward manner. As a result of avoiding complex components such as for example coupling housings with coupling and elastic intermediate layers to prevent the transfer of vibrations, production costs are low, as the costs for parts are eliminated and the installation time is reduced.

(8) Furthermore, in the case of a hydraulic unit according to the disclosure, the motor pump assembly can be equipped with special lifting devices, in order to change the unit as a whole, such that downtimes are cut and the installation time is reduced.

REFERENCE LIST

(9) 5 positive displacement pump 6 pump housing 7 pump shaft 8 front side of 6 9 front side of 6 11 intermediate plate 12 inert mass 13 intermediate plate 14 housing of 15 15 electric motor 16 motor shaft 17 recess in 16