Electromechanical brake system for motor vehicles

Abstract

The present invention relates to an electromechanical braking device for a motor vehicle, comprising an electric servo motor, by means of which a friction brake lining can be frictionally pressed against a brake body for braking the motor vehicle. The method comprises transmitting an operating force of the servo motor for the friction brake lining to a brake actuator via a transmission mechanism with a transmission gear, the brake actuator converting the rotational movement of the transmission gear into a linear movement of the friction brake lining, wherein the transmission gear can be fixed in a rotationally fixed manner by means of an adjusting mechanism in such a way that the friction brake lining pressed against the brake body remains pressed against the brake body for achieving parking brake, wherein the adjusting mechanism has a sliding sleeve axially adjacent to the transmission gear with respect to the rotation axis of the transmission gear, and in order to fix the transmission gear in a rotationally fixed manner, the sliding sleeve can be moved in the direction of the transmission gear, and the sliding sleeve can be coupled to the transmission gear by means of a positive-fit coupling.

Description

Technical Field

[0001] The invention relates to an electromechanical braking device for a motor vehicle. Background Art

[0002] EP 2 041 446 B1 discloses an electromechanical braking device for a motor vehicle. This braking device includes an electric servomotor, which can be used to frictionally apply a friction brake lining to a brake body designed as a brake disk, thereby braking the motor vehicle. To apply the friction brake lining to the brake disk, the actuating force of the servomotor applied to the friction brake lining can be transmitted via a transmission mechanism with a transmission gear to a brake actuator, which converts the rotational movement of the transmission gear into linear movement of the friction brake lining. To implement a parking brake, also known as a parking brake, the transmission gear of the transmission mechanism can be fixed or locked in a rotationally fixed manner by means of an adjustment mechanism so that the friction brake lining abutting the brake body remains in contact with the brake body. The parking brake is implemented using a freewheel. The freewheel is electromechanically switchable and operates in a form-fitting manner. Its design is comparable to that of an electric motor. The freewheel has, as a locking element, a pivotable tooth which can be pivoted into the involute toothing of the pinion of the servomotor so that the tooth meshes with the pinion.

[0003] A further electromechanical braking device is known from DE 102 34 848 A1, which has a switchable freewheel as a parking brake. Summary of the Invention

[0004] The object of the present invention is to provide an alternative electromechanical braking device for motor vehicles with a parking brake.

[0005] The object on which the present invention is based is achieved by the electromechanical braking device described below.

[0006] The brake mechanism of the present invention is characterized in that the brake mechanism is connected to the transmission gear and the control gear is connected to the control gear so that the friction brake lining is pressed against the brake body in a friction manner, thereby braking the vehicle.

[0007] Due to the axial proximity, ie the arrangement of the sliding sleeve in the axial direction next to the transmission gear, the parking brake can be integrated into the brake device in a very compact manner or in an optimal manner with respect to installation space.

[0008] If hydraulic or pneumatic systems are omitted, the electromechanical brake device is a true so-called “dry” brake-by-wire application, since no fluidic systems, such as hydraulic or pneumatic systems, are used.

[0009] With the aid of a solution that is solely electromechanical, short braking response times can be achieved, which is also reflected in the achievable braking distance.

[0010] Another advantage resides in favorable manufacturability.

[0011] The electric parking brake makes it possible to implement additional comfort functions, such as assisted starting on hills. However, this function can also be implemented by other driver assistance systems.

[0012] The sliding sleeve can be fixed arbitrarily to clamp the transmission mechanism. For example, the transmission gear can be fixed relative to a transmission mechanism housing or a servomotor or a brake actuator or a support component of the transmission mechanism.

[0013] In a particularly advantageous embodiment with regard to the forces to be supported in the transmission, the transmission gear is mounted rotatably and axially displaceably on a shaft, which is accommodated in a rotationally fixed manner in a carrier component of the transmission and is connected to the sliding sleeve by means of a shaft-hub connection. This shaft-hub connection can have, for example, a geared shaft profile, a splined shaft profile, a polygonal profile, serrations, or an additional follower element, such as a key. This shaft-hub connection can also be used for the connection between the shaft and the carrier component. Furthermore, an interference fit can also be used there.

[0014] It can also be provided that the shaft-hub connection between the shaft and the sliding sleeve has a rotational play that matches the mutually facing axial toothing of the form-fitting coupling. The axial toothing is shaped such that, when positively coupled to the transmission gear, the sliding sleeve rotates against the elastic force of a spring, in particular a torsion spring, thereby securing the axial toothing in the circumferential direction against one another under the elastic force of the torsion spring, preventing the form-fitting coupling from automatically opening. The rotational play can ensure, for example, that the parking brake is always engaged, regardless of the rotational angular position of the two coupling halves of the form-fitting coupling. Since it can advantageously be provided that the sliding sleeve always rotates in the same rotational direction relative to the transmission gear, the axial toothing can be shaped asymmetrically.

[0015] One possible solution for creating an asymmetrical axial toothing is a claw coupling whose teeth have an insertion bevel in only one of the two circumferential directions. Therefore, when the insertion bevels contact each other, the sleeve always rotates in the same direction. If the sleeve has an axial toothing and a spline shaft profile or a toothed shaft profile, the sleeve meshes doubly (inner and outer). The shaft can advantageously have a corresponding external toothing, into which the internal toothing of the sleeve meshes.

[0016] It can be provided that the sliding sleeve can be moved along the opening direction of the form-fit coupling by means of a force accumulator, thereby ensuring reliability.

[0017] The force accumulator can in particular be a compression spring which is supported axially on the shaft on the one hand and on a collar which extends radially inwards from the sliding sleeve on the other hand.

[0018] It can be advantageous for smooth operation of the energy storage device or the sleeve if the energy storage device is arranged in a space delimited partly by the shaft and partly by the sleeve, wherein the sleeve has a pressure equalization opening which establishes a balanced connection between the space and the environment.

[0019] In particular, to enable the use of an inexpensive, high-speed rotating motor, the transmission gear can be non-rotatably connected to an intermediate gear. The intermediate gear is arranged on the side of the transmission gear facing away from the sliding sleeve, and the intermediate gear has an external toothing that meshes with the external toothing of a pinion gear. The pinion gear is non-rotatably connected to the motor shaft of the servo motor. The shaft is arranged offset and parallel to the motor shaft. The transmission gear has external teeth and meshes with the driven gear of the brake actuator. The pinion gear is smaller than the intermediate gear, and the transmission gear is smaller than the driven gear of the brake actuator. According to this structural design, the transmission mechanism can have a transmission ratio of i>1.

[0020] For the accessibility of the friction brake lining, the electric servomotor and the adjustment mechanism of the parking brake, it can be advantageous to arrange these components or their connections mainly on the same side of the brake device. In this respect, it can be provided that

[0021] - the shaft,

[0022] - an operating screw of the brake actuator and

[0023] - the motor shaft of the servo motor

[0024] are arranged in parallel and offset to each other; a heat sink is provided on the end of the servo motor away from the pinion; an operating mechanism is arranged on the shaft on one side of this end, by means of which the sliding sleeve can be moved in the direction of the transmission gear; and the friction brake lining is arranged on the operating screw on the same side. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Further features, possible applications and advantages of the present invention are apparent from the following description of an exemplary embodiment of the present invention, which is illustrated with the aid of the accompanying drawings.

[0026] Figure 1 An electromechanical braking device for a motor vehicle is shown, comprising a transmission gear, an intermediate gear, and a positive coupling;

[0027] Figure 2 Shown according to Figure 1 details of the electromechanical braking device in the region of the form-fitting coupling; and

[0028] Figure 3 Shown according to Figure 1 Details of the electromechanical braking device in the area of ​​the transmission gear, intermediate gear and form-locking coupling. DETAILED DESCRIPTION

[0029] Figure 1 An electromechanical braking device is shown for a motor vehicle (not shown in further detail). The motor vehicle comprises two braking devices arranged on the rear axle. A braking device is assigned to each rear axle drive wheel of the motor vehicle, the braking device having a brake body 2 designed as a brake disk.

[0030] The brake device includes an electric servomotor 4, by means of which a friction brake lining 6 can be frictionally pressed against a brake body 2 for braking the motor vehicle. To this end, the actuating force of the servomotor 4 for the friction brake lining 6 can be transmitted via a transmission 8 to a brake actuator 10, which converts a rotational motion into a linear motion of the friction brake lining 6 and is designed, for example, as a spindle drive.

[0031] The transmission 8 has three rotation axes 12, 13, and 15 arranged parallel to each other and offset from each other. The motor shaft 30 is arranged coaxially with respect to the first rotation axis 12. The shaft 14 is arranged coaxially with respect to the second rotation axis 13 and is accommodated in a rotationally fixed manner in a carrier component 16, which is part of the transmission housing or the support structure of the brake device (not shown in further detail). A transmission gear 18 and an intermediate gear 20 connected to it in a rotationally fixed manner are roller-mounted and rotatably arranged on the shaft 14. The roller mounting of the intermediate gear 20 is achieved indirectly via a sleeve-shaped region 21 of the carrier component 16, into which the end of the shaft 14 is inserted using a press fit. The brake actuator 10 is arranged coaxially with respect to the third rotation axis 15. Its rotatably mounted housing 33 has an output gear 22 on its outer circumference.

[0032] The intermediate gear 20 and the transmission gear 18 are integrally formed. The intermediate gear 20 has an external toothing 24 that meshes with an external toothing 26 of a pinion 28, which is non-rotatably connected to a motor shaft 30 of the servomotor 4. The shaft 14 is arranged parallel to and offset from the motor shaft 30. The transmission gear 18 has external teeth and meshes with a driven gear 22 of the brake actuator 10.

[0033] The transmission 8 has a transmission ratio of i>1. To this end, the pinion 28 is smaller than the intermediate gear 20, and the transmission gear 18 is smaller than the output gear 22 of the brake actuator 10. The transmission 8 thus has two successive "reduction stages" or gear ratio stages that result in a lower speed.

[0034] To clamp the brake disc between the friction brake lining 6 and the other friction brake lining 32, thereby braking the wheel connected to the brake disc, the servomotor 4 is energized, causing its motor shaft 30 to rotate in a first direction of rotation. The gear mechanism 8 causes the housing 33 of the brake actuator 10 to rotate. This causes the actuating screw 34 of the spindle drive to extend, on which the friction brake lining 6 is supported. To this end, the actuating screw 34 is supported in a rotationally fixed manner relative to the friction brake lining 6 and / or the carrier component 16. The actuating screw 34 is then moved toward the brake disc until the brake disc is clamped to the desired degree between the two friction brake linings 6, 32.

[0035] When the brake disc is clamped or squeezed between the two friction surfaces 6 , 32 , the parking brake, which will be described in more detail below, is actuated if the vehicle is to be parked.

[0036] The sliding sleeve 36 is provided with Figure 2 The shaft-hub connection 38 shown is connected to the shaft 14 in a rotationally fixed manner with rotational play, so that the transmission gear 18 can be fixed in a rotationally fixed manner relative to the carrier part 16. The shaft-hub connection 38 has a toothed shaft profile with the rotational play.

[0037] The parking brake has a sleeve-like sliding sleeve 36 on the side of the transmission gear 18 facing away from the intermediate gear 20 , which can be locked by means of a sleeve for securing the transmission gear 18 in a rotationally fixed manner. Figure 3 The schematically shown actuating element 41 is displaceable coaxially relative to the shaft 14 in the direction of the transmission gear 18. The sleeve 36 can thus be coupled to the transmission gear 18 by means of a positive coupling 42. The sleeve 36 and the associated actuating element 41 form part of an adjustment mechanism 40. The actuating element 41 can be, for example, an electromagnet, a linear motor, or an electric motor with a rocker arm.

[0038] The positive-locking coupling 42 is designed as a claw coupling and, in this respect, has two axial toothings 46, 48, each of which is assigned to one of the two coupling halves. The teeth of the two coupling halves have insertion bevels 50, 52 in only one of the two circumferential directions. Because the rotational play is limited, each tooth of one coupling half of the positive-locking coupling 42 is assigned a corresponding tooth of the other coupling half. A torsion spring 44 is provided which, when the positive-locking coupling 42 is engaged, presses the two corresponding teeth against each other in the circumferential direction about the second rotational axis 13. Therefore, even if the actuating mechanism 41 is not energized, the positive-locking coupling 42 remains in the engaged position as long as the transmission gear 18 is held in the circumferential position by the friction linings 6, 32, which are frictionally abutting against the brake disk. Therefore, the rotational play matches the mutually facing axial toothings 46, 48 of the form-fit coupling 42, which are shaped so that the sliding sleeve 36 rotates against the spring force of the torsion spring 44 when it is positively coupled to the transmission gear 18. Therefore, the axial toothings 46, 48, which abut against each other in the circumferential direction under the spring force of the torsion spring 44, are fixed when the actuating mechanism 41 is not energized, preventing the form-fit coupling 42 from opening automatically.

[0039] After the sleeve 36 is coupled to the spur gear 18 via the form-fit coupling 42, the servomotor 4 can be switched off. The contact force of the brake friction linings 6, 32 on the brake disc 2 is reduced accordingly, depending on the rotational play at the shaft-hub connection 38. This force reduction is caused by the travel of the actuating screw 34 away from the brake disc. This very short travel can amount to, for example, 0.015 mm. By tightening the two axial toothings 46, 48, the sleeve 36 is secured against axial movement, allowing the actuating mechanism 41 to move back again. The actuating mechanism 41 does not need to be permanently energized, whether the parking brake is engaged or disengaged.

[0040] The sliding sleeve 36 can be moved into its starting position or in the opening direction of the form-fit coupling 42 by means of a force accumulator 54. The force accumulator 54 is a compression spring which is supported axially on the shaft 14 on the one hand and on a collar 56 which extends radially inwards from the sliding sleeve 36 on the other hand.

[0041] The compression spring is partially accommodated in a blind hole in the shaft 14. By means of this blind hole as additional structural length, a relatively long compression spring can be used.

[0042] The energy storage device 54 is arranged in a space 58 which is partially delimited by the shaft 14 and partially by the sliding sleeve 36, wherein the sliding sleeve 36 has Figure 3 A pressure equalization opening 60 is shown, which produces an equalization connection between the chamber 58 and the surroundings.

[0043] In the case that the operating member 41 is designed as an electromagnet, the components belonging to this electromagnet can be arranged in the space 58 and around the force storage device 54 designed as a compression spring, which is not in the space 58. Figure 3 The component of such an electromagnet can be, for example, a coil and, in particular, a tubular armature.

[0044] A cooling body 62 is provided on the end of the servo motor 4 away from the pinion 28. On one side of this end, the adjusting mechanism 40 ( Figure 3 The friction brake lining 6 is arranged on the same side as the actuating screw 34 .

[0045] In an alternative embodiment, the intermediate gear 2 and the transmission gear 18 are not integral with each other, but are connected to each other in a rotationally fixed manner in other ways. For example, the intermediate gear 2 and the transmission gear 18 can be pressed or contracted on a common hollow shaft.

Claims

1. An electromechanical brake device for a motor vehicle, comprising an electric servomotor (4) with which a friction brake lining (6) can be pressed frictionally against a brake body (2) for braking the motor vehicle, wherein the operating force of the servomotor (4) for the friction brake lining (6) can be transmitted via a transmission mechanism (8) with a transmission gear (18) to a brake actuator (10), which converts the rotational movement of the transmission gear (18) into a linear movement of the friction brake lining (6), wherein: The transmission gear (18) can be fixed in a rotationally fixed manner by means of an adjusting mechanism (40) in such a way that a friction brake lining (6) abutting against a brake body (2) remains abutting against the brake body (2) for achieving parking brake, characterized in that the adjusting mechanism (40) has a sliding sleeve (36) axially adjacent to the transmission gear (18) with respect to the rotation axis (13) of the transmission gear, and in order to fix the transmission gear (18) in a rotationally fixed manner, the sliding sleeve can be moved in the direction of the transmission gear (18) and can be coupled to the transmission gear (18) by means of a form-fitting coupling (42).

2. The braking device according to claim 1, characterized in that The transmission gear (18) is supported rotatably and axially displaceably on a shaft (14), which is received in a rotationally fixed manner in a support part (16) of the transmission mechanism (8) and is connected to the sliding sleeve (36) by means of a shaft-hub connection (38).

3. The braking device according to claim 2, characterized in that The shaft-hub connection (38) between the shaft (14) and the sliding sleeve (36) has a rotational clearance, which matches the mutually facing axial tooth sections (46, 48) of the form-fitting coupling (42). The axial tooth sections are shaped so that when the form-fitting coupling is connected to the transmission gear (18), the sliding sleeve (36) rotates against the elastic force of the spring, so that the axial tooth sections (46, 48) that are in contact with each other in the circumferential direction under the action of the elastic force are fixed, preventing the form-fitting coupling (42) from opening automatically.

4. The braking device according to claim 1 or 2, characterized in that: The form-fit coupling (42) is a claw coupling whose teeth have insertion bevels (50, 52) only in one of two circumferential directions.

5. The braking device according to claim 1, wherein: The sliding sleeve (36) is movable in an opening direction of the form-fit coupling (42) by means of a force accumulator (54).

6. The braking device according to claim 5, characterized in that The force accumulator (54) is a compression spring which is supported axially on the shaft (14) on the one hand and on a collar (56) which extends radially inwards from the sliding sleeve (36) on the other hand.

7. The braking device according to claim 5 or 6, characterized in that: The force storage device (54) is arranged in a space (58) which is partially delimited by the shaft (14) and partially by the sleeve (36), wherein the sleeve (36) has a pressure equalization opening (60) which establishes a balanced connection between the space (58) and the environment.

8. The braking device according to claim 2, characterized in that: The transmission gear (18) is connected to the intermediate gear (20) in a rotationally fixed manner, the intermediate gear is arranged on the side of the transmission gear (18) facing away from the sliding sleeve (36), and the intermediate gear has an external tooth portion (24) that meshes in the external tooth portion (26) of the pinion (28), and the pinion is connected to the motor shaft (30) of the servo motor (4) in a rotationally fixed manner; the shaft (14) is arranged in a parallel and offset manner relative to the motor shaft (30); the transmission gear (18) is externally toothed and meshes with the driven gear (22) of the brake actuator (10); the pinion (28) is smaller than the intermediate gear (20); and the transmission gear (18) is smaller than the driven gear (22) of the brake actuator (10).

9. The braking device according to claim 8, characterized in that - the shaft (14), - an operating screw (34) of the brake actuator (10) and - the motor shaft (30) of the servo motor (4) The servo motor (4) and the drive shaft (14) are arranged in an offset manner and in parallel with each other; a cooling body (62) is provided on the end of the servo motor (4) away from the pinion (28); an operating mechanism (41) is arranged on the shaft (14) on one side of this end, by means of which the sliding sleeve (36) can be moved in the direction of the transmission gear (18); and the friction brake lining (6) is arranged on the operating screw (34) on the same side.

10. The braking device according to claim 3, characterized in that The spring is a torsion spring (44).

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