PRESSURE GENERATION UNIT FOR A BRAKING SYSTEM

Abstract

The disclosure relates to a pressure generation unit for a braking system. The pressure generation unit comprises an electric drive motor and a hydraulic piston which is displaceable by the electric drive motor in order to selectively apply pressure to or relieve pressure from a pressure fluid circuit delimited by the hydraulic piston. For this purpose, the electric drive motor is drivingly coupled to the hydraulic piston via a planetary gear mechanism and a rack-and-pinion gear mechanism.

Claims

1. A pressure generation unit for a braking system, comprising: an electric drive motor and a hydraulic piston which is displaceable by the electric drive motor in order to selectively apply pressure to or relieve pressure from a pressure fluid circuit delimited by the hydraulic piston, wherein the electric drive motor is drivingly coupled to the hydraulic piston via a planetary gear mechanism and a rack-and-pinion gear mechanism.

2. The pressure generation unit according to claim 1, wherein the planetary gear mechanism is interposed in a power flow between the electric drive motor and the rack-and-pinion gear mechanism.

3. The pressure generation unit according to claim 1, wherein the electric drive motor is a brushless DC motor.

4. The pressure generation unit according to claim 1, wherein an effective axis of the hydraulic piston and a rotational axis of the electric drive motor are oriented perpendicularly to one another.

5. The pressure generation unit according to claim 1, wherein an output shaft of the electric drive motor is coupled to a sun gear of the planetary gear mechanism in a rotationally fixed manner.

6. The pressure generation unit according to claim 1, wherein, a planet carrier of the planetary gear mechanism or a ring gear of the planetary gear mechanism is coupled to a pinion of the rack-and-pinion gear mechanism in a rotationally fixed manner.

7. The pressure generation unit according to claim 1, wherein the hydraulic piston is rigidly connected to a rack of the rack-and-pinion gear mechanism.

8. The pressure generation unit according to claim 1, wherein a motor control unit is arranged on a side of the electric drive motor facing away from the planetary gear mechanism.

9. The pressure generation unit according to claim 1, wherein a motor control unit is arranged on a side of the rack-and-pinion gear mechanism facing away from the planetary gear mechanism.

10. The pressure generation unit according to claim 8, wherein a rotational angle sensor element is positioned in or on an output shaft of the electric drive motor, the rotational angle sensor element being positioned at an end of the output shaft adjacent to the motor control unit.

11. The pressure generation unit according to claim 2, wherein the electric drive motor is a brushless DC motor.

12. The pressure generation unit according to claim 2, wherein an effective axis of the hydraulic piston and a rotational axis of the electric drive motor are oriented perpendicularly to one another.

13. The pressure generation unit according to claim 12, wherein an output shaft of the electric drive motor is coupled to a sun gear of the planetary gear mechanism in a rotationally fixed manner.

14. The pressure generation unit according to claim 13, wherein an output shaft of the electric drive motor is coupled to a sun gear of the planetary gear mechanism in a rotationally fixed manner.

15. The pressure generation unit according to claim 14, wherein, a planet carrier of the planetary gear mechanism or a ring gear of the planetary gear mechanism is coupled to a pinion of the rack-and-pinion gear mechanism in a rotationally fixed manner.

16. The pressure generation unit according to claim 15, wherein the hydraulic piston is rigidly connected to a rack of the rack-and-pinion gear mechanism.

17. The pressure generation unit according to claim 16, wherein a motor control unit is arranged on a side of the electric drive motor facing away from the planetary gear mechanism.

18. The pressure generation unit according to claim 7, wherein a motor control unit is arranged on a side of the rack-and-pinion gear mechanism facing away from the planetary gear mechanism.

19. The pressure generation unit according to claim 18, wherein a rotational angle sensor element is positioned in or on an output shaft of the electric drive motor, the rotational angle sensor element being positioned at an end of the output shaft adjacent to the motor control unit.

20. The pressure generation unit according to claim 9, wherein a rotational angle sensor element is positioned in or on an output shaft of the electric drive motor, the rotational angle sensor element being positioned at an end of the output shaft adjacent to the motor control unit.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0021] The disclosure is explained below with reference to various exemplary arrangements which are shown in the accompanying drawings, in which:

[0022] FIG. 1 shows a pressure generation unit according to the disclosure in a first exemplary arrangement and

[0023] FIG. 2 shows a pressure generation unit according to the disclosure in a second exemplary arrangement.

DETAILED DESCRIPTION

[0024] FIG. 1 shows a pressure generation unit 10 for a hydraulic braking system.

[0025] The pressure generation unit 10 comprises an electric drive motor 12 which is coupled to a hydraulic piston 18 via a planetary gear mechanism 14 and a rack-and-pinion gear mechanism 16.

[0026] The planetary gear mechanism 14 is located in a power flow between the electric drive motor 12 and the rack-and-pinion gear mechanism 16. The planetary gear mechanism 14 is also geometrically positioned between the electric drive motor 12 and the rack-and-pinion gear mechanism 16.

[0027] The hydraulic piston 18 delimits a pressure fluid circuit 20, which is represented in FIG. 1 by a pressure chamber.

[0028] A motor control unit 22 is also provided to control the drive motor 12. This is positioned on a side of the electric drive motor 12 facing away from the planetary gear mechanism 14.

[0029] In one exemplary arrangement, all components of the pressure generation unit 10 are arranged in a contiguous housing 24 which is composed of a control housing portion 24a, a drive housing portion 24b and a piston housing portion 24c. The piston housing portion 24c is also closed by a first end cap 26 and a second end cap 28.

[0030] Specifically, in the exemplary arrangement shown, the electric drive motor 12 is constructed as a brushless DC motor and comprises a stator 30 which is immovably mounted in the drive housing portion 24b.

[0031] The stator 30 interacts with a rotor 32 which is seated on an output shaft 34 of the electric drive motor 12.

[0032] The output shaft 34 is rotatably mounted on the drive housing portion 24b via two bearings 36a, 36b.

[0033] The output shaft 34 can thus be rotated together with the rotor 32 about a rotational axis 38.

[0034] A rotational angle sensor element 40 which interacts with a rotational angle sensor unit 42 of the motor control unit 22 is also arranged at an end of the output shaft 34 adjacent to the motor control unit 22.

[0035] A rotational angle position of the output shaft 34 of the drive motor 12 can be detected by the rotational angle sensor unit 42.

[0036] In addition, the output shaft 34 is coupled to a sun gear 44 of the planetary gear mechanism 14 in a rotationally fixed manner.

[0037] The sun gear 44 also interacts with planet gears 46 which mesh in a manner known per se with a ring gear 48 and are rotatably mounted on a planet carrier 50.

[0038] The planet carrier 50 is connected to a pinion shaft 52 of the rack-and-pinion gear mechanism 16 in a rotationally fixed manner.

[0039] The pinion shaft 52 is rotatably mounted in the drive housing portion 24b via a first bearing 53a and is rotatably mounted in the piston housing portion 24c via a second bearing 53b.

[0040] A rotational axis of the pinion shaft 52 coincides with the rotational axis 38 of the output shaft 34.

[0041] A pinion 54 is seated on the pinion shaft 52 or a pinion toothing is incorporated into the pinion shaft 52.

[0042] The pinion 54 meshes with a rack 56 which is rigidly connected to the hydraulic piston 18.

[0043] The hydraulic piston 18 can thus be displaced by operating the electric drive motor 12 and rotating the pinion 54 via the planetary gear mechanism 14.

[0044] The rotational drive movement is converted into a translational movement of the hydraulic piston 18 by the pinion 54 and the rack 56.

[0045] Depending on the direction of displacement of the hydraulic piston 18, the pressure fluid circuit 20 is supplied with pressure or relieved of pressure.

[0046] An effective axis 58 of the hydraulic piston 18 is oriented perpendicularly to the rotational axis 38 of the drive motor 12.

[0047] FIG. 2 shows a second exemplary arrangement of the pressure generation unit 10. Only the differences from the first exemplary arrangement of the pressure generation unit 10 are discussed here. The same reference signs are used for comparable or corresponding components.

[0048] The motor control unit 22 is now arranged on a side of the rack-and-pinion gear mechanism 16 facing away from the planetary gear mechanism 14.

[0049] In the second exemplary arrangement, the rotational angle sensor element 40 is positioned at an end of the pinion shaft 52 that is arranged adjacent to the motor control unit 22. A rotational angle position of the pinion shaft 52 can thus be detected by the rotational angle sensor unit 42.

[0050] Since a gear ratio of the planetary gear mechanism 14 is known, it can also be used to infer a rotational angle position of the output shaft 34 of the drive motor 12.

[0051] In both exemplary arrangements, the pressure generation unit 10 is designed to be mounted on an associated motor vehicle above a brake master cylinder.

[0052] It should be emphasized that the torque output via the planet carrier is not to be understood as limiting. The torque output can also take place via a movable ring gear when the planet carrier is stationary. There are also other options for the torque input, as is also known for planetary gear mechanisms.