ELECTROMECHANICAL BRAKE PRESSURE GENERATOR INCLUDING SPINDLE DRIVE UNIT, BRAKING SYSTEM

Abstract

An electromechanical brake pressure generator including a spindle drive unit for converting a rotational motion of an electric motor-driven drive shaft into a translatory motion of a piston that is coupled to the spindle drive unit, the spindle drive unit being operatively connected to the drive shaft via a multi-stage transmission. The multi-stage transmission is a planetary gear set having a first and a second stage. With the aid of the transmission, a spindle or a spindle nut of the spindle drive unit is drivable, which is rotatably mounted in a housing of the brake pressure generator via a bearing assembly receiving axial and radial forces. A braking system for a vehicle including an electromechanical brake pressure generator is also described.

Claims

1-10. (canceled)

11. An electromechanical brake pressure generator, comprising: a spindle drive unit configured to convert a rotational motion of an electric motor-driven drive shaft into a translatory motion of a piston that is coupled to the spindle drive unit, the spindle drive unit being operatively connected with the drive shaft via a multi-stage transmission; wherein the multi-stage transmission is a planetary gear set including a first and a second stage, and wherein a spindle or a spindle nut of the spindle drive unit, which is drivable using the transmission, and which is rotatably mounted in a housing of the brake pressure generator via a bearing assembly receiving axial and radial forces.

12. The brake pressure generator as recited in claim 11, wherein the bearing assembly includes an axial needle bearing for receiving the axial forces and a radial slide bearing for receiving the radial forces.

13. The brake pressure generator as recited in claim 11, wherein the bearing assembly includes an angular ball bearing for receiving the axial and radial forces.

14. The brake pressure generator as recited in claim 11, wherein the bearing assembly is completely accommodated in the housing and/or fastened in the housing via an outer ring of the bearing assembly.

15. The brake pressure generator as recited in claim 14, wherein the outer ring is caulked or screwed in the housing.

16. The brake pressure generator as recited in claim 11, wherein the bearing assembly surrounds the spindle and/or the spindle nut.

17. The brake pressure generator as recited in claim 11, wherein the spindle is manufactured from or made of a metal, and/or the spindle nut is manufactured from or made of plastic.

18. The brake pressure generator as recited in claim 11, wherein the spindle is made of steel or aluminum.

19. The brake pressure generator as recited in claim 11, wherein the bearing assembly includes a pot-shaped inner ring that has a one-piece or a multi-part configuration and a pot bottom for connecting with the spindle or the spindle nut and for connecting with the transmission via pins.

20. The brake pressure generator as recited in claim 11, wherein the bearing assembly is supported at the housing via a plastic ring in an axial direction.

21. The brake pressure generator as recited in claim 11, wherein an inner ring of the bearing assembly is supported at the housing via a plastic ring in an axial direction

22. The brake pressure generator as recited in claim 11, wherein the bearing assembly includes a clip ring that holds together the bearing assembly and/or forms a slide bearing.

23. A braking system for a vehicle, comprising: an electromechanical brake pressure generator including: a spindle drive unit configured to convert a rotational motion of an electric motor-driven drive shaft into a translatory motion of a piston that is coupled to the spindle drive unit, the spindle drive unit being operatively connected with the drive shaft via a multi-stage transmission; wherein the multi-stage transmission is a planetary gear set including a first and a second stage, and wherein a spindle or a spindle nut of the spindle drive unit, which is drivable using the transmission, and which is rotatably mounted in a housing of the brake pressure generator via a bearing assembly receiving axial and radial forces.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1 shows a longitudinal section through a first electromechanical brake pressure generator according to an example embodiment of the present invention including a spindle drive unit and a bearing assembly, having an axial needle bearing and a radial slide bearing.

[0025] FIGS. 2a) and 2b) shows an enlarged detail of FIG. 1, a) including a caulked outer ring and a one-piece inner ring and b) including a screwed outer ring and a multi-part inner ring.

[0026] FIGS. 3a) and 3b) shows a detail similarly to FIGS. 2a) and 2b), but including a bearing assembly designed as an angular ball bearing, a) including a one-piece inner ring, and b) including a multi-part inner ring as well as including a cage.

[0027] FIG. 4 shows a detail similarly to b), but including a modified outer ring and inner ring.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0028] Electromechanical brake pressure generator 1 illustrated in FIG. 1 includes a housing 9, in which a spindle drive unit 2 is accommodated that is coupled to a piston 4. Spindle drive unit 2 includes a spindle 6 that is rotatably mounted in housing 9 via a bearing assembly 8. A spindle nut 7 is situated on spindle 6 and secured against twisting with the aid of a torque support 16. In the case of a rotational motion of spindle 6, spindle nut 7 moves in the axial direction and, in the process, entrains piston 4, so that same is inserted deeper into a cylindrical pressure chamber 17 that is designed in housing 9.

[0029] Spindle 6 is driven by a drive shaft 3 that is operatively connected with spindle 6 via a multi-stage transmission 5 in the form of a planetary gear set. In the present case, transmission 5 includes a first stage 5.1 and a second stage 5.2. Second stage 5.2 includes planet sets that are mounted via pins 13. Pins 13 are, in turn, connected with a pot-shaped inner ring 11 of bearing assembly 8 that is put on spindle 6.

[0030] The pot shape of inner ring 11 allows bearing assembly 8 to be positioned at the level of spindle drive unit 2, so that bearing assembly 8 does not require additional installation space in the axial direction. The installation length of brake pressure generator 1 may thus be kept short. In addition, installation space available in housing 9 is used (see dashed lines) that is delimited upward by second stage 5.2 of transmission 5, downward by a housing wall for separating bearing assembly 8 from a brake cylinder 18, radially inward by torque support 16, and radially outward by a current and/or signal line 19.

[0031] As is apparent from the enlarged illustration of FIGS. 2a) and 2b), bearing assembly 8 of brake pressure generator 1 of FIG. 1 includes an axial needle bearing 8.1 and a radial slide bearing 8.2. Axial needle bearing 8.1 has needle-shaped rolling elements 20 that require only minor installation space in the axial direction. Radial slide bearing 8.2 is implemented on the left-hand side, i.e., in FIG. 2a), by a contact between outer ring 10 and inner ring 11 and on the right-hand side, i.e., in FIG. 2b), by a plastic ring that is inserted into an outer ring 10 of axial needle bearing 8.1.

[0032] In FIG. 2a), outer ring 10 is additionally fastened in housing 9 with the aid of a caulking 21. In FIG. 2b), the fastening is achieved with the aid of a screw connection 22.

[0033] In FIG. 2a) inner ring 11 has a one-piece design and in FIG. 2b) a multi-part design.

[0034] Both figures have in common a plastic ring 14, with the aid of which bearing assembly 8 is supported in the axial direction for the case that spindle 6 pulls in the axial direction during operation.

[0035] Pot-shaped inner ring 11 of bearing assembly 8 having a one-piece or multi-part design includes a pot bottom 12 having a central recess 23, in which spindle 6 is inserted. For a rotatably fixed connection, pot bottom 12 may be welded to spindle 6. Alternatively, recess 23 in pot bottom 12 and spindle 6 may include corresponding, not rotationally symmetric contours 24, 25. Pot bottom 12 moreover includes bores 26, into which pins 13 are pressed.

[0036] Further preferred specific embodiments are illustrated in FIGS. 3a) and 3b). Both specific embodiments have in common that here, bearing assembly 8 is formed from an angular ball bearing 8.3 including ball-shaped rolling elements 20. These may be guided through a cage 27, as is illustrated in FIG. 3b) by way of example. If a cage 27 is dispensed with, the number of rolling elements 20 may be increased to increase the load rating. Outer ring 10 is caulked in housing 9 in each case. Inner ring 11 has a one-piece design in FIG. 3a) and a multi-part design in FIG. 3b).

[0037] Angular ball bearing 8.3 illustrated in FIGS. 3a) and 3b) furthermore has a clip ring 15 that holds together inner ring 11 and outer ring 10. Angular ball bearing 8.3 may thus be pre-assembled and inserted into housing 9 of brake pressure generator 1 as a pre-assembled unit. In the present case, clip ring 15 has a two-part design to form a slide bearing at the same time.

[0038] A further specific embodiment is illustrated in FIG. 4. It is different from the one in FIG. 3b) in particular in that inner ring 11 includes more than two pieces, namely three pieces. A first piece forms pot bottom 12, a further piece forms actual inner ring 11 including the contact surface for rolling elements 20. A third piece connects the two pieces. Each piece may thus be manufactured from a suitable material according to its function. At the same time, each piece has a comparably simple shape, which simplifies the manufacture of inner ring 11.