Actuating device for brake system

Abstract

The invention relates to an actuating device (1) for a brake system (2), comprising: an electric motor (19), the rotor (20) of which is arranged in a rotationally fixed manner on a rotatably mounted drive shaft (21); a movably mounted pressure element (3); a transmission (22) by means of which the drive shaft (21) is operatively connected to the pressure element (3) in such a way that the pressure element (3) can be moved by rotation of the drive shaft (21), the transmission (22) having a movable spindle (23); and a rotation stop device (29), which acts between the spindle (23) and the housing (7) of the actuating device (1) and has a rotation gap (35). According to the invention, the actuating device (1) has a spring element (40), which exerts a preload force on the spindle (23) in order to close the rotation gap (35).

Description

Technical Field

[0001] The present invention relates to an operating device for a brake system, comprising: an electric motor, wherein the rotor of the electric motor is arranged in a rotationally fixed manner on a rotatably supported drive shaft; a movably supported pressure element; a transmission device, through which the drive shaft and the pressure element are effectively connected so that the pressure element can be moved by rotation of the drive shaft, wherein the transmission device has a movable screw; and a rotation stop device, which acts between the screw and the housing of the operating device and has a rotational clearance. Background Art

[0002] The hydraulic brake system of a motor vehicle usually has a plurality of friction brake devices. The friction brake device is effectively connected to the operating device of the brake system so that the friction brake device can be operated by the operating device. As the degree of electrification of motor vehicles continues to increase, the operating device of the brake system is also increasingly electrified. In this regard, it is known that the operating device for the brake system is equipped with an electric motor, wherein the rotor of the electric motor is arranged in a rotationally fixed manner on a rotatably supported drive shaft. In order to enable the friction brake device to be operated by the operating device, the operating device also has a movably supported pressure element. The drive shaft is effectively connected to the pressure element by a transmission device so that the pressure element can be moved by the rotation of the drive shaft. Therefore, the transmission device is configured to convert the rotation of the drive shaft into a translational movement of the pressure element. For this purpose, the transmission device usually has a movable screw. In order to limit the rotation of the screw during the operation of the operating device, there is usually a rotation stop device acting between the screw and the housing of the operating device. In order to achieve low-friction movement of the screw, the rotation stop device usually has a rotational clearance. However, this leads to the following problem: a click or knock sound will occur during the operation of the operating device. Summary of the invention

[0003] The actuating device according to the invention with the features of claim 1 has the advantage that the actuating device generates very little noise during operation. According to the invention, it is provided that the actuating device has a spring element, which applies a preload to the threaded spindle in order to close the rotational gap. Since the rotation stop has a rotational gap, the threaded spindle can at least rotate slightly relative to the housing. In principle, the threaded spindle can rotate in a first rotational direction in which the rotational gap is closed and in a second rotational direction in which the rotational gap is opened. If the rotational gap is closed, a sufficiently large force acting on the threaded spindle in the first rotational direction causes the threaded spindle to move in the direction of the pressure element. If the friction brake device is actuated by the actuating device, the motor is then actuated in such a way that it provides a force acting on the threaded spindle in the first rotational direction. If the rotational gap is opened before the motor is actuated, the threaded spindle is first rotated in the first rotational direction by the provided force. Only when the rotational gap is closed does the threaded spindle move in the direction of the pressure element. However, closing the rotational gap is accompanied by the aforementioned rattling or knocking noises. These noises can be avoided by the spring element according to the invention. According to the invention, the preload provided by the spring element acts on the threaded spindle in order to close the rotational gap, i.e. in the first rotational direction. Preferably, the spring element is designed in such a way that the rotational play is closed by the preload. Since the rotational play is already closed by the preload, it is not necessary to close the rotational play first when the friction brake is actuated by the electric motor. This prevents rattling or knocking noises. According to a preferred embodiment, the transmission has a spindle transmission, wherein the spindle transmission has a threaded spindle. According to an alternative embodiment, the transmission preferably has a ball screw drive, wherein the ball screw drive has a threaded spindle.

[0004] Preferably, the rotation stop device has at least one first stop connected to the screw in a rotationally fixed manner and at least one second stop arranged in a fixed manner on the housing, wherein the spring element presses the first stop toward the second stop for closing the rotation gap. If the first stop abuts against the second stop, the rotation gap is closed. If the first stop is spaced apart from the second stop, the rotation gap is at least partially open. Preferably, the first stop is oriented in the first rotation direction. Then, correspondingly, the second stop is oriented opposite to the first rotation direction, that is, oriented in the second rotation direction. When the rotation gap is closed, the screw is mechanically firmly guided in the housing by the stop.

[0005] Preferably, the spring element is a helical spring. This embodiment of the spring element keeps the manufacturing costs low. In addition, the spring element designed as a helical spring can be integrated into the operating device in a space-saving manner.

[0006] According to a preferred embodiment, it is provided that the preload force is a torsional force. Therefore, the spring element is twisted in such a way that it provides the preload force as a torsional force. In this embodiment, the spring element is preferably arranged in such a way that the longitudinal center axis of the spring element is oriented parallel to the longitudinal center axis of the screw. According to an alternative embodiment, it is preferably provided that the preload force is a compressive force. Therefore, the spring element is compressed in such a way that it provides the preload force as a compressive force. According to an alternative embodiment, it is preferably provided that the preload force is a tensile force. Therefore, the spring element is stretched so that it provides the preload force as a tensile force. In the two aforementioned embodiments, the spring element is preferably arranged in such a way that the longitudinal center axis of the spring element is oriented perpendicular to the longitudinal center axis of the screw.

[0007] According to a preferred embodiment, the spring element is designed in such a way that, in addition to applying a preload force to the threaded spindle, it also applies a restoring force directed away from the pressure element. The function of the spring element is thus extended in such a way that, after actuation of the friction brake device, the spring element resets the threaded spindle. In this embodiment, the spring element is preferably designed in such a way that the preload force is a torsional force. The spring element is then twisted in such a way that it provides the preload force as a torsional force and is compressed or stretched in such a way that it provides the restoring force as a compressive force or a tensile force.

[0008] Preferably, the lead screw and the spring element are arranged coaxially with respect to one another. This allows the spring element to be integrated into the operating device in a space-saving manner. In addition, in the case of a coaxial arrangement of the lead screw and the spring element, the aforementioned tilting or warping of the lead screw due to the restoring force is avoided. Preferably, the spring element radially surrounds the lead screw relative to the longitudinal center axis of the lead screw.

[0009] According to a preferred embodiment, the first end of the spring element is arranged on the threaded spindle or on an element connected to the threaded spindle in a rotationally fixed manner, thereby achieving a reliable transmission of the preload force to the threaded spindle.

[0010] According to a preferred embodiment, the threaded spindle has a first end section facing away from the pressure element, the first end section has an axial stop, and the first end of the spring element is arranged on the axial stop. The first end section facing away from the pressure element is technically easy to access, so the spring element is preferably arranged on the axial stop of the first end section.

[0011] Preferably, the second end of the spring element is arranged on the housing or on an element arranged in a fixed manner on the housing. This achieves a mechanically stable support of the spring element, thereby achieving a reliable transmission of the preload force to the threaded spindle.

[0012] Preferably, the second end of the spring element is arranged on a bearing ring of a rotary bearing of the actuating device, which is fixed to the housing. In this way, a mechanically stable arrangement of the second end of the spring element can be achieved. As mentioned above, the transmission preferably has a spindle transmission, wherein the spindle transmission has a lead screw. Particularly preferably, the spindle nut of the spindle transmission is rotatably supported by a rotary bearing. The rotary bearing is therefore used not only to support the lead screw nut, but also to support the spring element.

[0013] Preferably, the threaded spindle cooperates directly with the housing to form a rotation lock. This provides a particularly mechanically stable rotation lock. Since the threaded spindle cooperates directly with the housing to form the rotation lock, the tolerance chain with respect to the rotation lock is also minimized.

[0014] According to an alternative embodiment, it is preferably provided that the rotation-stop element is connected to the screw in a rotationally fixed manner and that the rotation-stop element directly cooperates with the housing to form a rotation-stop device. This can reduce the weight and / or manufacturing costs for the operating device. For this purpose, the rotation-stop element is preferably made of plastic. In contrast, the screw is preferably made of a metal material. Particularly preferably, the rotation-stop element is arranged on the second end section of the screw facing the pressure element.

[0015] According to a preferred embodiment, the housing has at least one radial recess into which a radial projection of the screw or a radial projection of the rotation-stop element radially engages to form a rotation-stop device. A mechanically stable rotation-stop device is thereby obtained. Preferably, the radial recess is configured as a groove extending through the housing in the displacement direction of the screw. Preferably, the screw or the rotation-stop element has a plurality of radial projections, each radial projection radially engaging in a corresponding other radial recess of the housing. Particularly preferably, there are two radial projections, which are diametrically opposite to each other relative to the longitudinal center axis of the screw. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention is described in detail below with reference to the accompanying drawings.

[0017] Figure 1 A cross-sectional view showing an operating device for a brake system;

[0018] Figure 2 another cross-sectional view showing the operating device; and

[0019] Figure 3 An enlarged detail view of the manipulator is shown. DETAILED DESCRIPTION

[0020] Figure 1A longitudinal section through an actuating device 1 of a brake system 2, not shown in detail, for a motor vehicle is shown. The actuating device 1 has a movably mounted pressure element 3, which in the present case is designed as a pressure rod 3. The pressure element 3 can be moved along its longitudinal center axis 4 in a first direction 5 and in a second direction 6 opposite to the first direction 5. The pressure element 3 is at least partially arranged in a housing 7 of the actuating device 1. The housing 7 has a housing wall 8 which is closed in the circumferential direction and is therefore cylindrical. The housing wall 8 forms or surrounds the housing interior of the housing 7.

[0021] A master brake cylinder 9 of the actuating device 1 is arranged on the housing 7 in a housing-fixed manner. In the present case, the master brake cylinder 11 is arranged on a first end face 10 of the housing wall 8. In the master brake cylinder 9, a first hydraulic piston 11 and a second hydraulic piston 12 are supported movably, that is, they are supported movably in a first direction 5 and a second direction 6. The master brake cylinder 9 has a plurality of hydraulic connections 13, 14. If the actuating device 1 is installed in the brake system 2 as required, the hydraulic connections 13, 14 are fluidically connected to the slave cylinders of the friction brake device of the brake system 2. The friction brake device can then be actuated by moving the hydraulic pistons 11 and 12 in the first direction 5. The pressure element 3 is coupled to the hydraulic pistons 11 and 12 in such a way that the hydraulic pistons 11 and 12 can be moved in the first direction 5 by the pressure element 3. Thus, the friction brake device can be actuated by moving the pressure element 3. A housing plate 15 is arranged on the housing 7 in a housing-fixed manner. In the present case, the housing plate 15 is arranged on a second end face 16 of the housing wall 8 facing away from the first end face 10. The housing plate 15 at least partially closes the housing interior of the housing 7 .

[0022] The operating device 1 also has a drive unit 17. The drive unit 17 has a motor housing 18, in which an electric motor 19 is arranged. An annular rotor 20 of the electric motor 19 is arranged in a rotationally fixed manner on a drive shaft 21, wherein the drive shaft 21 is mounted in a rotatable manner about an axis of rotation 49. The motor housing 18 is fastened to the housing 7.

[0023] The drive shaft 21 is coupled to the pressure element 3 through the transmission 22 so that the pressure element 3 can be moved by the rotation of the drive shaft 21. Therefore, the transmission 22 is configured to convert the rotation of the drive shaft 21 into a translational movement of the pressure element 3. For this purpose, the transmission 22 has a movable screw 23. The screw 23 can move along the first direction 5 and the second direction 6. In the present case, the screw 23 is a component of the screw drive mechanism 24 of the transmission 22. The screw drive mechanism 24 has a screw nut 25 in addition to the screw 23. The screw nut 25 is rotatably supported by a rotary bearing 26. The drive tooth 27 of the screw 23 meshes with the output tooth 28 of the screw nut 25. The screw nut 25 can be rotated by the rotation of the drive shaft 21. In the present case, the screw nut 25 is effectively connected to the drive shaft 21 through a worm gear mechanism that cannot be seen in the figure.

[0024] In order to prevent the screw 23 from rotating with the screw nut 25 when the screw nut 25 rotates, the screw 23 is provided with a rotation stop 29. The rotation stop 29 acts between the screw 23 and the housing 7 and limits the rotation of these two elements relative to each other. Figure 2 A cross section of the actuating device 1 in the region of the rotation stop 29 is shown. In the present case, the actuating device 1 has a rotation stop element 30, which is connected to the threaded spindle 23 in a rotationally fixed manner. The rotation stop element 30 cooperates with the housing 7 to form the rotation stop 29. According to another embodiment, the rotation stop element 30 is omitted, wherein the threaded spindle 23 then cooperates directly with the housing 7 to form the rotation stop 29. In the present case, the rotation stop element 30 has two radial projections 31, which radially engage in corresponding further radial recesses 32 of the housing 7 to form the rotation stop 29. In the present case, the radial projections 31 are diametrically opposite to each other with respect to the longitudinal center axis of the threaded spindle 23. The radial recess 32 is designed as a groove 32 extending through the housing 7 in the axial direction.

[0025] from Figure 2It can be seen that the width 33 of the radial recess 32 is greater than the width 34 of the radial projection 31. Accordingly, the rotation stop 29 has a rotation gap 35, so that the screw 23 can at least slightly rotate relative to the housing 7. Here, the screw 23 can in principle rotate in a first rotation direction 36 that closes the rotation gap 35 and in a second rotation direction 37 that opens the rotation gap 35. If the rotation gap 35 is closed, a sufficiently large force acting on the screw 23 in the first rotation direction 36 causes the screw 23 to move in the direction of the pressure element 3, that is, in the first direction 5. If the friction brake device is to be actuated by the actuating device 1, the motor 19 is actuated in such a way that it provides a force acting on the screw 23 in the first rotation direction 36. If the rotation gap 35 is opened before the motor 19 is actuated, the screw 23 is first rotated in the first rotation direction 36 by the force provided. Only when the rotation gap 35 is closed does the screw 23 move in the first direction 5. However, the closing of the rotation gap 35 is accompanied by a click or knock sound. Figure 2 In the illustrated operating device 1, the rotation gap 35 is closed. Figure 2 It can be seen in FIG. 1 that when the rotational gap 35 is closed, the first stop 38 of the radial projection 31 abuts against the second stop 39 of the radial recess 32 .

[0026] Figure 3 Another longitudinal section through the actuating device 1 in the region of the threaded spindle 23 is shown. Figure 3 , it can be seen that the actuating device has a spring element 40. The spring element 40 applies a preload to the spindle 23 in order to close the rotational gap 35. The preload thus acts on the spindle 23 in a first rotational direction 36. Due to the preload, the rotational gap 35 is always closed, in particular independently of the actuation of the motor 19. Since the rotational gap 35 is closed by the preload, the rotational gap 35 does not first need to be overcome or closed by the motor 19 when the friction brake device is actuated. This prevents the aforementioned rattling or knocking noises from occurring.

[0027] According to the embodiment shown in the figures, the spring element 40 is designed as a helical spring 40. The spring element 40 is arranged coaxially with the threaded spindle 23 and surrounds the threaded spindle 23 radially with respect to the longitudinal center axis of the threaded spindle 23.

[0028] The screw 23 has a first end section 41 facing away from the pressure element 3, and the first end section has an axial stop 42. The axial stop 42 faces the pressure element 3. The first end 43 of the spring element 40 is arranged on the axial stop 42. The spring element 40 also has a second end 44. The second end 44 is arranged on a bearing ring 45 of the rotary bearing 26 fixed to the housing. However, other arrangements of the spring element 40 are also possible. For example, according to another embodiment, the first end 43 is not arranged on the screw 23, but on the rotation stop element 30. According to another embodiment, the second end 44 is not arranged on the bearing ring 45, but is, for example, directly arranged on the housing 7.

[0029] According to the embodiment shown in the figure, the spring element 40 is rotated so that it provides a preload as a torsional force. In addition, the spring element 40 is compressed so that the screw 23 is loaded with a reset force directed away from the pressure element 3 in addition to the preload. However, other embodiments of the spring element 40 are also possible. According to another embodiment, the spring element 40 is arranged in one of the radial recesses 32 and is compressed so that it provides a compression force acting on the radial protrusion 31 in the first rotational direction 36. Even in this embodiment, the rotation gap 35 can be closed by the spring element 40.

[0030] The actuating device 1 further comprises an actuating element 50, which is movably supported in an axial through-hole 51 of the threaded spindle 23. A first end 52 of the actuating element 50 is coupled or can be coupled to a brake pedal of the brake system 2 via an input rod 53, so that the actuating element 50 can then be moved by actuating the brake pedal. A second end 54 of the actuating element 50 is coupled to the pressure element 3 in such a way that the pressure element 3 can be moved by the actuating element 50. Thus, the friction brake device can also be actuated by actuating the brake pedal.

Claims

1. An operating device for a brake system, comprising: an electric motor (19), wherein a rotor (20) of the electric motor (19) is arranged in a rotationally fixed manner on a rotatably supported drive shaft (21); a movably supported pressure element (3); a transmission device (22), via which the drive shaft (21) and the pressure element (3) are operatively connected, so that the pressure element (3) can be moved by rotation of the drive shaft (21), wherein: The transmission device (22) has a movable spindle (23); and a rotation stop device (29), which acts between the spindle (23) and the housing (7) of the operating device (1) and has a rotation gap (35), and is characterized by a spring element (40) that applies a preload to the spindle (23) in order to close the rotation gap (35).

2. The operating device according to claim 1, characterized in that At least one first stop (38) connected to the threaded spindle (23) in a rotationally fixed manner and at least one second stop (39) arranged in a housing-fixed manner, wherein the spring element (40) presses the first stop (38) toward the second stop (39) in order to close the rotational gap (35).

3. An operating device according to any one of the preceding claims, characterized in that The spring element (40) is a helical spring (40).

4. An operating device according to any one of the preceding claims, characterized in that The preload force is a torsional force, a compressive force or a tensile force.

5. An operating device according to any one of the preceding claims, characterized in that The spring element (40) is designed in such a way that it exerts a restoring force directed away from the pressure element (3) on the threaded spindle (23) in addition to the preload force.

6. An operating device according to any one of the preceding claims, characterized in that The threaded spindle (23) and the spring element (40) are arranged coaxially with respect to one another.

7. An operating device according to any one of the preceding claims, characterized in that The first end (42) of the spring element (40) is arranged on the threaded spindle (23) or on an element which is connected to the threaded spindle (23) in a rotationally fixed manner.

8. The operating device according to claim 7, characterized in that The threaded spindle (23) has a first end section (41) facing away from the pressure element (3), which has an axial stop (42), and a first end (43) of the spring element (40) is arranged at the axial stop (42).

9. An operating device according to any one of the preceding claims, characterized in that The second end (44) of the spring element (40) is arranged on the housing (7) or on an element which is arranged so as to be fixed to the housing.

10. The operating device according to claim 9, characterized in that The second end (44) of the spring element (40) is arranged on a bearing ring (45) of a rotary bearing (26) of the actuating device (1) which is arranged fixed to the housing.

11. An operating device according to any one of the preceding claims, characterized in that The threaded spindle (23) interacts directly with the housing (7) to form the rotational locking device (29).

12. The operating device according to any one of claims 1 to 10, characterized in that A rotation-securing element (30) is connected to the threaded spindle (23) in a rotationally fixed manner and cooperates directly with the housing (7) to form the rotation-securing device (29).

13. The operating device according to any one of claims 11 and 12, characterized in that The housing (7) has at least one radial recess (32) into which a radial projection of the threaded spindle (23) or a radial projection (31) of the rotation-securing element (30) radially engages in order to form the rotation-securing device (29).

Images