Electromechanical Brake Booster

Abstract

The disclosed electromechanical brake booster for a vehicle brake system comprises a driving arrangement for driving at least one actuation device designed to actuate a brake cylinder. The driving arrangement includes at least one electric motor and a gear mechanism for coupling the electric motor to the at least one actuation device. The gear mechanism comprises at least one first spur gear and at least one second spur gear, the electric motor driving the first spur gear directly and the second gear via at least one intermediate gear.

Claims

1. (canceled)

2. (canceled)

3. (canceled)

4. (canceled)

5. (canceled)

6. (canceled)

7. (canceled)

8. (canceled)

9. (canceled)

10. (canceled)

11. (canceled)

12. (canceled)

13. (canceled)

14. (canceled)

15. (canceled)

16. (canceled)

17. An electromechanical brake booster for an electrohydraulic motor vehicle braking system, with a drive assembly for driving at least one actuator designed to actuate a brake cylinder, wherein the drive assembly has at least one electric motor and a gear mechanism for coupling the electric motor to the at least one actuator, wherein the gear mechanism has at least one first spur gear and at least one second spur gear, wherein the electric motor drives the first spur gear directly and drives the second spur gear via at least one intermediate gear.

18. The electromechanical brake booster as claimed in claim 17, wherein the actuator has at least one toothed rack section which can be coupled to the gear mechanism.

19. The electromechanical brake booster as claimed in claim 18, wherein the actuator has a first and a second toothed rack section which are arranged on opposite sides of the actuator.

20. The electromechanical brake booster as claimed in claim 17, wherein the first spur gear, the intermediate gear and the second spur gear are arranged in the same plane in the direction of the axis of rotation of the electric motor.

21. The electromechanical brake booster as claimed in claim 17, wherein the first spur gear and the intermediate gear are arranged offset with respect to each other in the direction of the axis of rotation of the electric motor.

22. The electromechanical brake booster as claimed in claim 21, wherein the second spur gear and the intermediate gear are located in the same plane in the direction of the axis of rotation of the electric motor.

23. The electromechanical brake booster as claimed in claim 20, wherein a pinion is provided on the output shaft of the electric motor to drive the first spur gear and the intermediate gear, wherein the pinion is located in the same plane as the first spur gear, the second spur gear and the intermediate gear in the direction of the axis of rotation of the electric motor.

24. The electromechanical brake booster as claimed in claim 21, wherein at least one pinion is provided on the output shaft of the electric motor, which pinion is designed to drive the first spur gear and the intermediate gear which is offset with respect to the first spur gear in the direction of the axis of rotation of the electric motor.

25. The electromechanical brake booster as claimed in claim 24, wherein the extension of the at least one pinion spans at least the axial extension of the outer peripheral surfaces of the first spur gear and the intermediate gear in the direction of the axis of rotation of the electric motor.

26. The electromechanical brake booster as claimed in claim 17, wherein at least the first spur gear, the second spur gear and the intermediate gear have helical gearing.

27. The electromechanical brake booster as claimed in claim 17, wherein the first spur gear and the second spur gear are each connected to a shaft, each of which has a gear wheel.

28. The electromechanical brake booster as claimed in claim 17, wherein the drive assembly includes at least one control unit which is configured to actuate the at least one electric motor.

29. The electromechanical brake booster as claimed in claim 17, wherein the drive assembly when installed in a motor vehicle is arranged such that the axis of rotation of the electric motor extends perpendicularly to the longitudinal axis of the actuator and at a predetermined angle to the vertical axis of the vehicle.

30. The electromechanical brake booster as claimed in claim 17, wherein the actuator comprises at least one first actuating element which can be charged with a pedal force exerted on a brake pedal, and at least one second actuating element which is driven by the electric motor via the gear mechanism.

31. The electromechanical brake booster as claimed in claim 17, wherein the electromechanical brake booster can be installed on a motor vehicle by means of at least one fastening device, wherein the at least one fastening device defines a mounting plane in which the longitudinal axis of the at least one actuator lies.

32. An electrohydraulic motor vehicle braking system with a brake cylinder and an electromechanical brake booster comprising a drive assembly for driving at least one actuator designed to actuate the brake cylinder, wherein the drive assembly has at least one electric motor and a gear mechanism for coupling the electric motor to the at least one actuator, wherein the gear mechanism has at least one first spur gear and at least one second spur gear, wherein the electric motor drives the first spur gear directly and drives the second spur gear via at least one intermediate gear.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 is a perspective view of an electromechanical brake booster according to one embodiment.

[0026] FIG. 2 is a perspective view of the electromechanical brake booster with an alternative arrangement of the gear mechanism, electric motor and control unit.

[0027] FIG. 3 is a perspective view of the electromechanical brake booster with an alternative arrangement of the gear mechanism, electric motor and control unit.

[0028] FIG. 4 is a perspective view of the electromechanical brake booster with an alternative arrangement of the gear mechanism, electric motor and control unit.

[0029] FIG. 5 is a perspective view of the electromechanical brake booster with an alternative arrangement of the gear mechanism, electric motor and control unit.

[0030] FIG. 6 is a perspective view of the electromechanical brake booster with an alternative arrangement of the gear mechanism, electric motor and control unit.

[0031] FIG. 7 is a perspective view of the electromechanical brake booster with an alternative arrangement of the gear mechanism, electric motor and control unit.

[0032] FIG. 8 is a perspective view of an electromechanical brake booster with a gear mechanism according to a first design variant.

[0033] FIG. 9 is a perspective view of an electromechanical brake booster with a gear mechanism according to the first design variant.

[0034] FIG. 10 is a perspective view of an electromechanical brake booster with a gear mechanism according to the first design variant.

[0035] FIG. 11 is a perspective view of an electromechanical brake booster with a gear mechanism according to the first design variant.

[0036] FIG. 12 is a perspective view of an electromechanical brake booster with a gear mechanism according to a second design variant.

[0037] FIG. 13 is a perspective view of an electromechanical brake booster with a gear mechanism according to the second design variant.

[0038] FIG. 14 is a perspective view of an electromechanical brake booster with a gear mechanism according to the second design variant.

[0039] FIG. 15 is a perspective view of an electromechanical brake booster with a gear mechanism according to the second design variant.

[0040] FIG. 16 is a perspective view of an electromechanical brake booster with a gear mechanism according to the second design variant.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] It should be noted that in the figures described below, the toothing arrangements of the individual gearwheels, toothed racks, etc., are shown only schematically. It is understood that a suitable toothing is present in each case, which may also be embodied for example as helical gear toothing to enable the gear mechanism elements to mesh with each other.

[0042] FIG. 1 shows a perspective view of an electromechanical brake booster, which is generally designated 10.

[0043] Electromechanical brake booster 10 comprises a motor 12, a control unit 14, a gear mechanism 16 and an actuator 18. Actuator 18 is coupled to a brake cylinder 20. Electro-mechanical brake booster 10 and braking cylinder 20 form one assembly.

[0044] A pinion 24 is provided on an output shaft 22 of electric motor 12. Pinion 24 drives a first spur gear 26 and an intermediate gear 28 directly, without interposed components. A second spur gear 30 is driven via intermediate gear 28. Spur gears 26 and 30 each drive a shaft 32, 34. A gear wheel or toothed roller 36, 38 is provided on each of the shafts 32 and 34. Gear wheels 36 and 38 each engage with a toothed rack section 40, 42 on actuator 18. The toothed rack sections 40, 42 are disposed on opposite sides of the actuator 18. The respective toothing arrangements of these elements 24, 26, 28, 30, 36, 38, 40, 42 are only shown schematically.

[0045] Actuator 18 includes a first actuating element 44 and a second actuating element 46. Toothed rack sections 40, 42 are provided on the second actuating element 46, and engage with gear wheel 36, 38. The first actuating element 44 may be acted upon by a braking force exerted on a brake pedal by a driver of the vehicle. This causes the first actuating element 44 to be moved towards brake cylinder 20. The boost force requested by the driver is generated by actuator 18, which is driven by electric motor 12 via gear mechanism 16.

[0046] For this purpose, second actuating element 46 is moved towards brake cylinder 20, by electric motor 20 via the gear mechanism 16 and in particular via gear wheels 36, 38 and toothed rack sections 40, 42 to deliver the driver's requested boost force additionally to braking cylinder 20. The motion of actuator 18 with its actuating elements 44, 46 towards brake cylinder 20 has the effect of generating a hydraulic pressure in brake cylinder 20 that corresponds to the braking pressure requested by the driver. Brake cylinder 20 has two openings 48, 50 through which the braking circuits of the vehicle may be charged with hydraulic fluid and thus exposed to hydraulic pressure to generate a braking force at the wheel brakes. A reservoir for brake fluid or a pressure compensation tank may be disposed on the further opening 52 of brake cylinder 20.

[0047] A fastening means 54 with a flange 56 and openings 58 is provided in a region between the brake cylinder 20 and the actuator 18. Openings 58 are conformed to accommodate mounting bolts 60, 62. Mounting bolts 60, 62 may be inserted and secured in holes in a predetermined mounting position on the vehicle, for example on a bulkhead (not shown). The location of mounting holes 60, 62 is usually designated by the vehicle manufacturers.

[0048] FIG. 2 shows a front view of the electromechanical brake booster 10 shown in FIG. 1.

[0049] In FIG. 2 the vertical axis, the longitudinal axis and the transverse axis of the vehicle are indicated. The vertical axis of the vehicle is an axis which extends substantially in the vertical direction. The longitudinal axis A.sub.L of actuator 18 extends parallel to the longitudinal axis of the vehicle.

[0050] Control unit 14 is arranged between motor 12 and gear mechanism 16. Electric motor 12 drives gear mechanism 16, via which the two gear wheels 36 and 38 are driven to shift actuator 18 in the direction of longitudinal axis A.sub.L via toothed rack sections 40, 42. The displacement of actuator 18 along longitudinal axis A.sub.L causes the actuation of brake cylinder 20, of which only a brake fluid reservoir 64 is visible in FIG. 2.

[0051] The drive assembly consisting of motor 12, control unit 14 and gear mechanism 16 is

arranged at a predetermined angle relative to the vertical axis of the vehicle. The angle is dictated by the axis of rotation A.sub.1 of electric motor 12, which extends at a predetermined angle to the vertical axis of the vehicle. This angle may be 45. Similarly to the axis of rotation A.sub.1 of electric motor 14, the axes of rotation A.sub.2 and A.sub.3 of the spur gears 26, 30, the shafts 32, 34 and the gear wheels 36 and 38 extend at a predetermined angle relative to the vertical axis of the vehicle.

[0052] Electromechanical brake booster 10 is equipped with a fastening device 54. Fastening device 54 comprises a flange 56 having openings 58 and mounting bolts 60, 62. The mounting bolts 60, 62 are fixedly connected to the assembly and flange 56 on brake cylinder 20. Mounting bolts 60, 62 span a fastening plane BE. Fastening plane BE extends through center axes A.sub.4 and A.sub.5 of mounting bolts 60, 62. Fastening plane BE runs obliquely, at a predetermined angle to the vertical axis of the vehicle. The longitudinal axis A.sub.L of actuator 18 is located in fastening plane BE. The axis of rotation A.sub.1 of electric motor 12 extends perpendicularly to the longitudinal axis A.sub.L of actuator 18 and brake cylinder 20. The axis of rotation A.sub.1 of electric motor 12 extends perpendicularly to the fastening plane BE. The same applies to the axes of rotation A.sub.2 and A.sub.3 of spur gears 26, 30 and the components connected to the spur gears 26, 30. Axis of rotation A.sub.1 does not have to extend perpendicularly to the fastening plane, but may also extend at an angle of 60 to 120 to the fastening plane.

[0053] In the embodiment of the electromechanical brake booster 10 shown in FIG. 2, the electric motor 12, the control unit 14 and the gear mechanism 16 are arranged together on one side of actuator 18 and fastening plane BE. This makes it possible to create a particularly compact construction of the drive assembly for brake booster 10.

[0054] FIGS. 3 to 7 show further embodiments of electromechanical brake booster 10, which differ essentially in the arrangement of the motor 12, the control unit 14 and the gear mechanism 16. The drive assembly is arranged at the angle relative to the vertical axis of the vehicle predetermined by the axis of rotation A.sub.1 of electric motor 12 irrespective of the arrangement of the drive assembly with the electric motor 12, the control unit 14 and the gear mechanism 16 on actuator 18. The axis of rotation A.sub.1 of electric motor 12 also extends perpendicularly to fastening plane BE and also perpendicularly to the longitudinal axis A.sub.L of actuator 18 in all embodiments.

[0055] FIG. 3 shows a front view of a further embodiment of the electromechanical brake booster 10, in which the electric motor 12 and the control unit 14 are disposed together on one side of the actuator 18 and the gear mechanism 14 is disposed on the other side of actuator 18. Also in this embodiment, axis of rotation A.sub.1 of electric motor 12 extends obliquely to the vertical axis of the vehicle and perpendicularly to fastening plane BE. Axes of rotation A.sub.2 and A.sub.3 of spur gears 26 and 30 extend obliquely, at a predetermined angle to the vertical axis of the vehicle but also perpendicularly to the fastening plane BE. The axis of rotation A.sub.1 of the electric motor extends perpendicularly to the longitudinal axis A.sub.L of actuator 18.

[0056] Gearbox 16 according to this embodiment differs structurally from the gear mechanism 16 described above. This variant of gear mechanism 16 will be discussed in detail later in this description with reference to FIGS. 12 to 16. Actuator 18 corresponds to the actuator described in detail with reference to FIGS. 1 and 2. However, is should be noted here that motor output shaft 22 extends from the side of the actuator 18 on which motor 12 is disposed to the other side with the gear mechanism 16, to be able to transmit a torque generated by the motor 12 to the gear mechanism 16.

[0057] FIG. 4 shows a front view of a further embodiment of brake booster 10.

[0058] In this embodiment, electric motor 12 is disposed on one side of actuator 18 and on one side of mounting plane BE. Gearbox 16 is arranged together with control unit 14 on the side of actuator 18 facing away from motor 12 and on the respective other side mounting plane BE. The axes of rotation A.sub.1, A.sub.2 and A.sub.3 extend obliquely, at a predetermined angle to the vertical axis of the vehicle and perpendicularly to the mounting plane BE. Axis of rotation A.sub.1 of the electric motor extends perpendicularly to the longitudinal axis A.sub.L of actuator 18.

[0059] FIG. 5 shows a perspective view of a further embodiment of the brake booster 10.

[0060] In this embodiment of brake booster 10, motor 12 together with gear mechanism 16 is provided on the side of actuator 18 and brake cylinder 20. Control unit 14 is also provided on the side of actuator 18 and brake cylinder 20 facing away from gear mechanism 16. In this embodiment as well, motor output shaft 22 extends from the side of the motor 12 to the side with gear mechanism 16. Motor output shaft 22 passes through mounting plane BE.

[0061] FIG. 6 shows a front view of the electromechanical brake booster 10 of FIG. 5.

[0062] Electric motor 12 and gear mechanism 16 are disposed on one side of actuator 18 and mounting plane BE. Control unit 14 is arranged on the respective other side of actuator 18 and mounting plane BE. The axes of rotation A.sub.1, A.sub.2 and A.sub.3 are oblique to the vertical axis of the vehicle, but perpendicular to the mounting plane BE.

[0063] The view according to FIG. 7 largely corresponds to the view according to FIG. 6. Parts of gear mechanism 16 and of motor output shaft 22 are obscured by a gear mechanism housing 66 for absorbing bearing loads of the axes of rotation A.sub.2 A.sub.3, A.sub.6 and rotating shafts.

[0064] FIG. 8 shows a perspective view of electromechanical brake booster 10 with a gear mechanism 16 according to a first design variant. Gearbox 16 has a first spur gear 26 and a second spur gear 30. The first spur gear 26 is driven directly by the motor shaft 22 via a pinion 24, outlined only schematically in FIG. 8, which is arranged on motor output shaft 22. An intermediate gear 28 is also driven directly by pinion 24. Intermediate gear 28 in turn drives the second spur gear 30. Intermediate gear 28 makes it possible to reverse the direction of rotation of second spur gear 30 compared with the rotational direction of first spur gear 26, so that the spur gears 26 and 30 rotate in opposite directions. The opposite directions of rotation of the first spur gear and the second spur gear are needed to enable actuator 18 to drive both spur gears 26 and 30.

[0065] First spur gear 26, intermediate gear 28, second spur gear 30 and pinion 24 on motor output shaft 22 are arranged in the same plane in the direction of the axis of rotation A.sub.1 of electric motor 12.

[0066] FIG. 9 shows a further perspective view of the brake booster 10 shown in FIG. 8.

[0067] Actuator 18 consists of a first actuating element 44 and a second actuating element 46. The second actuating element 46 may be driven by gear mechanism 16. For this purpose, the second actuating element 46 is equipped with toothed rack sections 40 and 42 in which gear wheels 36 and 38 engage. Gear wheels 36 and 38 are connected to the first spur gear 26 and the second spur gear 30 and are driven by the spur gears 26, 30. The first spur gear 26 is driven directly by the pinion 24 on motor output shaft 22. Pinion 24 on motor output shaft 22 drives intermediate gear 28, which in turn drives the second spur gear 30. When a braking force exerted by the driver on a brake pedal (not shown) is transmitted to the first actuating element 44, the actuating element 44 is moved in the direction of brake cylinder 20. Control unit 14 actuates motor 12 based on the braking force exerted on the brake pedal by the driver. Motor 12 drives gear mechanism 16 to shift the second actuating element 46 along the longitudinal axis A.sub.L of actuator 18 towards brake cylinder 20. By the displacement of the actuator 18 in the direction of the brake cylinder 20, the braking force is increased and a braking pressure is generated at the wheel brakes via brake cylinder 20 (not shown).

[0068] FIG. 10 shows a front view of the brake booster 10 shown in FIGS. 8 and 9.

[0069] FIG. 10 particularly shows that all the gears of gear mechanism 16 are in line or in one plane, i.e. the spur gears 26, 30, the intermediate gear 28 and the pinion 24 are not offset relative to each other in the direction of the axis of rotation A.sub.1 of the motor.

[0070] FIG. 11 shows a side view of the electromechanical brake booster 10 shown in FIGS. 8 to 10.

[0071] In FIG. 11, toothed rack section 40 is disposed above the longitudinal axis A.sub.L of actuator 18 on the second actuating element 46. Toothed rack section 42 is provided below the longitudinal axis A.sub.L of actuator 18 on the second actuating element 46. In order to be able to displace actuator 18 in the direction of brake cylinder 20, first end plate 26 drives the top toothed rack section 40 and second end plate 30 drives the bottom toothed rack section 42. Actuator 18 is connected to brake cylinder 20, which adjoins actuator 18 in the direction of longitudinal axis A.sub.L.

[0072] It is also evident from FIG. 11 that the first spur gear 26 is driven directly by motor output shaft 22, whereas intermediate gear 28 is arranged between pinion 24 and the second spur gear 30. The torque is transmitted from pinion 24 to the second spur gear 30 via intermediate gear 28.

[0073] Fastening means 54 is provided between brake cylinder 20 and actuator 18. Fastening means 54 includes mounting bolts 60, 62 which extend in the direction of the longitudinal axis of the vehicle and span the mounting plane BE.

[0074] FIG. 12 shows a perspective view of electromechanical brake booster 10 with a gear mechanism 16 according to a second design variant.

[0075] FIG. 12 shows that the first spur gear 26 and the second spur gear 30 lie in different planes. Intermediate gear 28 and first spur gear 26 are also offset from one another in the direction of the motor output shaft 22 and the axis of rotation A.sub.1 of electric motor 12.

[0076] A pinion 24 is provided on motor output shaft 22 and is able to drive the first spur gear 26 and the intermediate gear 28, although the first spur gear 26 and the intermediate gear 28 are offset with respect to each other in the direction of the axis of rotation A.sub.1. Pinion 24 is accordingly formed and dimensioned such that it spans the extension of the outer circumferential surfaces of the first spur gear 26 and the intermediate gear 28 in the direction of the axis of rotation A.sub.1 of electric motor 12 and so is able to drive both the first spur gear 26 and the intermediate gear 28. Motor output shaft 22 extends from motor 12 to gear mechanism 16, which is arranged on the other side of actuator 18. Motor output shaft 22 passes through mounting plane BE.

[0077] FIG. 13 shows a further perspective view of the electromechanical brake booster 10 shown in FIG. 12.

[0078] Actuator 18 is connected to a force transmitting member 68, which transmits a braking force applied to a brake pedal to actuator 18. Force transmitting member 68 is coupled to the first actuating element 44.

[0079] Motor output shaft 22, or pinion 24 on the motor output shaft 22, drives the first spur gear 26 and the intermediate gear 28 directly and without interposed components. Intermediate gear 28 drives second spur gear 30. The direction of rotation of the second spur gear 30 may be reversed via the intermediate gear 28, so that the first spur gear 26 and the second spur gear 30 rotate in opposite directions.

[0080] The second spur gear 30 and the intermediate gear 28 are arranged in the same plane in the direction of the axis of rotation A.sub.1. The first spur gear 26 is offset with respect to the intermediate gear 28 and the second spur gear 30 in the direction of the axis of rotation A.sub.1 of electric motor 12. In other words, intermediate gear 28 and second spur gear 30 are arranged in a different plane from first spur gear 26.

[0081] FIG. 14 shows a front view of the electromechanical brake booster 10 shown in FIGS. 12 and 13.

[0082] The axis of rotation A.sub.1 of electric motor 12 extends at a predetermined angle to the vertical axis of the vehicle. The axis of rotation A.sub.1 of electric motor 12 extends perpendicularly to mounting plane BE. In the direction of the axis of rotation A.sub.1 of electric motor 12, first spur gear 26 is offset from second spur gear 30 and intermediate gear 28. The axes of rotation A.sub.2 of the first spur gear 26, A.sub.3 of the second spur gear 30 and A.sub.6 of the intermediate gear 28 extend parallel to each other but perpendicularly to mounting plane BE and obliquely to the vertical axis of the vehicle.

[0083] FIG. 15 shows a view of an electromechanical brake booster 10, which is largely the same as the representation according to FIG. 14, but with the difference that gear mechanism 16 is embodied with a gear mechanism housing 68 for absorbing the bearing forces of the individual axes of rotation A.sub.2, A.sub.3, A.sub.6.

[0084] FIG. 16 shows a side view of electromechanical brake booster 10.

[0085] FIG. 16 also shows clearly that the second spur gear 30 and the intermediate gear 28 are disposed in the same plane. The first spur gear 26 is offset with respect to the second spur gear 30 and the intermediate gear 28. In the direction of the transverse axis of the vehicle, intermediate gear 28 partially overlaps first spur gear 26. The motor output shaft 22 protrudes below the overlap region between the first spur gear 26 and the intermediate gear 28. The first spur gear 26 and the intermediate gear 28 are driven directly by motor output shaft 22 even when the first spur gear 26 and the intermediate gear 28 are offset with respect to each other.

[0086] The principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.