MULTIDISC BRAKE FOR A MOTOR VEHICLE

Abstract

A multi-disk brake (1) for a motor vehicle has two multi-disk mechanisms (7, 8) and an actuation device (9) for brake actuation and/or brake release of the multi-disk mechanisms (7, 8), and an electric drive (16) for translational actuation (spreading) of the actuation device, such as, in particular, the ramp unit (9). During a spreading operation, the multi-disk mechanisms (7, 8) are pretensioned in a metered manner by the actuation device and produce a desired frictional engagement, and a correspondingly reversed activation of the actuating mechanism enables a correspondingly metered brake release. By means of the electric drive (16), the action of the multi-disk brake (1) can be metered overall in a particularly precise, sensitive and compensated manner in modern vehicle topology, including all peripheral brake components and systems, including recuperation.

Description

The invention relates to a multi-disk brake for a motor vehicle with a rotatable drive shaft and with a guide device fixed in relation to the drive shaft. The multi-disk brake comprises a multi-disk arrangement, further comprising alternately arranged lining disks and intermediate disks, wherein the lining disks are non-rotatably connected to the drive shaft or to the guide device and the intermediate disks are non-rotatably connected to the respective other component of the guide device or of the drive shaft, and with an actuation device for pretensioning (actuating) and/or releasing the multi-disk arrangement, and with an actuating mechanism/actuator as an actuating drive of the actuation device (brake actuation and/or brake release) according to the features of the preamble of claim 1.

Wet multi-disk brakes are already used in agricultural machinery and industrial trucks and are known from practice. The multi-disk brake is characterized by a very high brake parameter C*, a constant friction coefficient and an encapsulated design. As a rule, the multi-disk arrangement is arranged in an oil bath such that heat generated during braking can easily be dissipated and, in addition, no brake abrasion passes into the environment. In addition, such a multi-disk brake can be easily integrated in a drive train and can be easily scaled through the size and number of the lining disks and intermediate disks.

In the case of the multi-disk brake known from practice, the actuator is activated by a hydraulic supply in the vehicle. When the multi-disk brake is used in a passenger vehicle, there is also the need to be able to meter the braking power particularly precisely.

The invention is based on the problem of developing a multi-disk brake in such a way that, particularly in an electronic motor vehicle brake system that can additionally or separately include one or more electrical and/or hydraulic wheel brakes and/or a plurality of drive trains, such as, in particular, a recuperative brake system, said multi-disk brake can nevertheless be easily activated such that a braking power, such as, in particular, a total braking power of all the brakes or components in cooperation can nevertheless be easily metered.

This problem is solved according to the invention with a particularly simplified metering of the braking power on the basis of the characterizing features of claim 1. The design according to the invention allows the application force or braking power to be metered particularly sensitively and precisely using an electrical control. Furthermore, such an electric drive—in particular a reversible rotary drive—can efficiently drive an actuation device/ramp unit in both directions. This makes it possible to compensate for direction-dependent reinforcement or release effects of a wedge-like ramp device. The electric drive of the actuation device in both directions (brake actuation and/or brake release) enables a constant or regulated braking power as desired with or without the abovementioned compensation measure when driving backward as well as when driving forward. In addition, the inclusion of electrical control technology for peripheral systems and components in modern vehicle topology is made possible to a greater extent (braking cooperation and braking inclusion in a hybridized drive train with integrated regenerative brake). The multi-disk brake is released by driving the actuating mechanism in the brake release direction with a simultaneous corresponding resetting of the multi-disk arrangements by means of at least one return spring.

According to another advantageous development of the invention, the metering of the braking power is simplified if the electric drive is in the form of an electric motor with a pivotably mounted pinion which can be driven by the electric motor, and wherein the pinion supports a lever element or cam element. If the lever element or cam element is designed symmetrically, the same braking torque can be generated when driving forward and backward. An asymmetrical cam enables the braking torque to be adapted to different requirements when driving backward and forward.

In a further particular specification of a preferred refinement of the present invention, the actuation device is designed to a certain extent as a wedge gear, that is, as a ramp device/ramp (construction) unit, and in this context the actuating mechanism/actuator/electric drive can drive this ramp unit even more precisely, and efficiently and reversibly in both directions (brake actuation or brake release), for the purpose of braking force regulation/braking force control. The accordingly correspondingly further developed, sensitive and quickly controlled or regulated drive of the ramp unit in all directions enables a regulated braking performance and/or constant brake actuation sensation, especially in a backward direction of travel as well as in a forward direction of travel. In other words, a further advantageous effect of this improved refinement is that, with a short travel distance, in particular in terms of control technology, very sensitively translated and rapid or translationally converted control interventions on the actuation device/ramp device are made possible. The multi-disk brake is released by resetting the multi-disk arrangement with the aid of one or more return springs, and wherein the actuating mechanism actuates the actuation device/ramp unit in the release direction.

According to another advantageous development of the invention, friction losses when the multi-disk brake is actuated can be kept particularly low if the lever element has a roller bearing, and in that the roller bearing faces a control arm of the ramp unit. By reducing the friction between lever element and the ramp unit, the roller bearing increases the efficiency of the multi-disk brake and reduces hysteresis.

According to another advantageous development of the invention, the multi-disk brake is particularly compact if the pinion is designed as a toothed segment.

A parking brake customary in motor vehicles can be easily produced, according to another advantageous development of the invention, if the electric drive has an activatable parking brake device, and in that the parking brake device either blocks or releases the ramp unit in the position set by the actuator. This parking brake device preferably has a solenoid which holds the pinion in its position or releases its movement.

According to another advantageous development of the invention, the parking brake device is structurally particularly simple if the parking brake device has an electromagnetically activatable ratchet wheel, and in that the ratchet wheel meshes with the pinion or the electric drive for either blocking or release.

According to another advantageous development of the invention, the activation of the ramp unit is structurally particularly simple if the ramp unit has a rotatable ramp disk supported on the multi-disk pack, in that the ramp disk can be displaced in the axial direction upon rotation, and in that the actuator is designed to rotate the ramp disk.

According to another advantageous development of the invention, self-boosting of the braking power of the multi-disk brake can be generated in the same way when driving forward or backward if the ramp unit has two ramp disks arranged between two multi-disk arrangements, and if one ramp disk can be driven in one direction and the other ramp disk in the other direction for the displacement in the axial direction. As a result of this design, depending on the direction of rotation of the shaft, the ramp disk necessary for the self-boosting of the multi-disk brake can be selected and rotated in the same direction of rotation as the adjacent disk of the multi-disk arrangement. This self-boosting leads to an increasing braking torque and thus to an increasing brake parameter C*, as a result of which the required actuating force can be reduced.

The optional drive of one or the other ramp disk depending on the drive direction of the electric drive is particularly simple, according to another advantageous development of the invention, if the ramp disks each have a control arm, in that the lever element is arranged between the control arms, and in that the ramp disks of the guide device have support arms which are at a distance opposite one another.

According to another advantageous development of the invention, friction losses of the ramp unit can be kept particularly low if the ramp disk has tapering grooves for partially receiving balls. As a result of this design, the balls roll on the edges of the tapering grooves and protrude differently depending on the rotational position of the ramp disk. This produces the axial displacement of the ramp disk.

According to another advantageous development of the invention, the multi-disk brake is structurally particularly simple if the guide device is non-rotatably connected to a housing.

According to another advantageous development of the invention, the multi-disk brake can be manufactured particularly cost-effectively if the guide device has guide pins fastened in the housing.

According to another advantageous development of the invention, cooling of the multi-disk brake is particularly simple if the housing is designed to be open toward a transmission of the motor vehicle. Since the vehicle transmission in motor vehicles has oil lubrication in any case, the oil in the transmission can be provided for cooling the multi-disk brake. This makes the multi-disk brake particularly suitable for use in motor vehicles.

According to another advantageous development of the invention, the generation of an intended braking torque when driving forward and backward is particularly simple if the actuator can be activated depending on the direction of rotation of the drive shaft. In this way, one ramp disk can be rotated in one direction of rotation of the drive shaft and the other ramp disk in the other direction of rotation.

The invention permits numerous embodiments. To further illustrate its basic principle, one of these embodiments is illustrated in the drawing and will be described in the following text. In the drawing:

FIG. 1 shows a front view of a multi-disk brake fastened to a transmission,

FIG. 2 shows a top view of the multi-disk brake from FIG. 1,

FIG. 3 shows a sectional illustration through the multi-disk brake from FIG. 1 along the line III-III,

FIG. 4 shows a sectional illustration through the multi-disk brake from FIG. 2 along the line IV-IV,

FIG. 5 shows an exploded illustration of some components of the multi-disk brake from FIG. 1, and

FIG. 6 shows a schematic diagram of the system.

FIG. 1 shows a multi-disk brake 1 with a housing 2, with an actuating mechanism, i.e. an actuator 3, as the actuating mechanism, and with a flange 5, which is non-rotatably arranged on a drive shaft 4, for connecting a drive train, not illustrated, of a motor vehicle. The housing 2 of the multi-disk brake 1 is fastened to a schematically illustrated transmission 6 of a motor vehicle.

FIG. 2 shows the multi-disk brake 1 from FIG. 1 in a top view with a partial region of the transmission 6. The drive shaft 4 can be connected to a transmission output shaft (not illustrated) of the transmission 6. The housing 2 of the multi-disk brake 1 is open toward the transmission 6 such that a lubricant circuit of the transmission 6 reaches the multi-disk brake 1 and lubricates and cools the latter.

FIG. 3 shows, in a sectional illustration through the multi-disk brake 1 from FIG. 1 along the line III-III, that the multi-disk brake 1 has two multi-disk arrangements 7, 8 and, between the multi-disk arrangements 7, 8, an actuation device in the form of a ramp unit 9 with two ramp disks 10, 11. The multi-disk arrangements 7, 8 alternately have lining disks 12 and intermediate disks 13. The lining disks 12 are arranged non-rotatably and axially displaceably on the drive shaft 4, while the intermediate disks 13 are arranged nonrotatably and axially displaceably on a guide device 14. The guide device 14 has guide pins 15 fastened in the housing 2. The axial mobility of the lining disks 12 and the intermediate disks 13 is limited by the housing 2 and the guide device 14.

During the braking operation, the ramp disks 10, 11 of this preferred actuation device are rotated relative to one another. The ramp disks 10, 11 move axially apart and press the multi-disk arrangements 7, 8 together. These cause a frictional engagement between the drive shaft 4 rotatable by the transmission 6 and the guide device 14 fixed to the housing 2.

FIG. 4 shows, in a sectional illustration along the line IV-IV from FIG. 2 through the central region of the multi-disk brake 1, the connection of the adjusting mechanism/actuator 3 to the actuation device/ramp unit 9. The adjusting mechanism/the actuator 3 has an electric drive 16 with an actuator gear 17. The actuator gear 17 has a pinion 18 designed as a toothed segment with a lever element 19. The lever element 19 carries a roller bearing 20 and is arranged between control arms 21, 22 of the two ramp disks 10, 11. Furthermore, the ramp disks 10, 11 have support arms 23, 24 with which they face the guide pins 15. When the pinion 18 is driven by the electric drive 16, the lever element 19 is deflected to one of the control arms 22, as a result of which the associated ramp disk 11 is rotated. As a result, the support arm 24 of this ramp disk 11 is at a large distance A from the next guide pin 15. The other ramp disk 10 is supported with the support arm 23 on the next guide pin 15′.

In a further embodiment, not illustrated, the lever element 19 is designed as a control cam and is arranged on an axis of rotation of the pinion 18.

FIG. 5 shows some components of the multi-disk brake 1 in an exploded illustration. It can be seen here that the electrical actuating mechanism/electric drive has an electric motor 25. The actuator gear 17 is arranged between the electric motor 25 and the pinion 18 having the lever element 19. Balls 26 which are guided in tapering grooves 27 of the ramp disks 10, 11 are arranged between the ramp disks 10, 11. The grooves 27 are aligned tangentially to the direction of rotation of the ramp disks 10, 11. As a result of the tapering, the balls 26 are moved out axially with respect to one another depending on the rotational position of the ramp disks 10, 11, and the ramp disks 10, 11 are thus spread apart.

Return springs for releasing the pretensioning/actuation of the multi-disk arrangements 7, 8 when the actuator 3 is not energized are not illustrated, in order to simplify the drawing. Such return springs are fastened to the ramp disks 10, 11 and press these ramp disks 10, 11 against the balls 26 arranged between them.

FIG. 6 shows a sufficiently self-explanatory, schematic and preferred brake/drive train system relationship with regard to the mechatronic system which the present invention incorporates in a particularly advantageous manner. A friction brake F.B in the form of the multi-disk brake 1 cooperates and communicates with a recuperatively acting drive (brake) train (R.B.S) for the purpose of generating a total braking force effect ΣFb, which is made up additively of a frictional braking force component and a recuperative (drive) braking force component. Merely for the sake of clarification, it should also be added that an electromechanically actuable multi-disk brake, as is shown structurally by way of example as a preferred solution proposal with reference to FIGS. 1-5, in principle is not intended to or does not have to include an implicit release functionality. This is because a multi-disk brake is not readily automatically put in a position to be released automatically or currentlessly after the brake has been actuated. Rather, it is primarily provided according to the invention that a release force is applied externally, separately, on the basis of one or more pretensioned return springs. Accordingly, according to the invention, there is by no means necessarily a rigid coupling in the brake release direction between the ramp disk 10, 11 and the drive 16.

• 1 Multi-disk brake
• 2 Housing
• 3 Actuator
• 4 Drive shaft
• 5 Flange
• 6 Transmission
• 7 Multi-disk arrangement
• 8 Multi-disk arrangement
• 9 Ramp unit
• 10 Ramp disk
• 11 Ramp disk
• 12 Lining disk
• 13 Intermediate disk
• 14 Guide device
• 15 Guide pin
• 16 electr. drive
• 17 Actuator gear
• 18 Pinion
• 19 Lever gear
• 20 Roller bearing
• 21 Control arm
• 22 Control arm
• 23 Support arm
• 24 Support arm
• 25 Electric motor
• 26 Ball
• 27 Groove
• Bat. Power supply (e.g. accumulator/battery/PowerCap)
• D.B.R. (Driver Brake Request)=driver brake actuation/brake release
• ECU electronic (brake) control unit
• Ext. Com. cross-system, external communication/data bus
• F.B. Friction brake
• R.B.S. recuperative (drive)/braking system
• S (brake) load measuring device
• ΣFb Total braking force
• - - - Signal flow
• ______ Flow of energy

Claims

1. A multi-disk brake (1) for a motor vehicle with a rotatable drive shaft (4) and with a guide device (14) fixed in relation to the drive shaft (4), with a multi-disk arrangement/multi-disk pack (7, 8) comprising alternately arranged lining disks (12) and with intermediate disks (13), wherein the lining disks (12) are non-rotatably connected to the drive shaft (4) or to the guide device (14) and the intermediate disks (13) are non-rotatably connected to the respective other component of the guide device (14) or the drive shaft (4), further comprising an actuation device, such as, in particular, a ramp unit (9), for the purpose of actuating/pretensioning the multi-disk arrangement/multi-disk pack (7, 8) and with an actuating mechanism/actuator (3) for actuating and/or releasing the actuating device (9), characterized in that the actuating mechanism/actuator (3) has an electric drive (16).

2. The multi-disk brake as claimed in claim 1, characterized in that the electric drive (16) is designed as a rotationally reversible rotary drive with a rotating shaft.

3. The multi-disk brake as claimed in claim 1 and/or 2, characterized in that the electric drive (16) has an electric motor (25) with a pivotably mounted pinion (18) which can be driven by the electric motor (25) and the pinion (18) supports a lever element (19) or cam element.

4. The multi-disk brake as claimed in claim 3, characterized in that the lever element (19) has a roller bearing (20), and in that the roller bearing (20) faces a control arm (21, 22) of the ramp unit (9).

5. The multi-disk brake as claimed in claim 3 or 4, characterized in that the pinion (18) is designed as a toothed segment.

6. The multi-disk brake as claimed in one or more of claims 1 to 5, characterized in that the electric drive (16) has an activatable parking brake device (28), and in that the parking brake device (28) either blocks or releases the actuation device, such as in particular a ramp unit (9), in the position set by the actuator (3).

7. The multi-disk brake as claimed in claim 6, characterized in that the parking brake device (28) has an electromagnetically activatable ratchet wheel (29), and in that the ratchet wheel (29) meshes with the pinion (18) or the electric drive (16).

8. The multi-disk brake as claimed in one or more of claims 1 to 7, characterized in that the actuation device is present in the form of a ramp unit (9) and has a rotatable ramp disk (10, 11) supported on the multi-disk pack (7, 8), in that the ramp disk (10, 11) can be displaced in the axial direction upon rotation depending on the rotational position, and in that the actuator (3) is designed to rotate the ramp disk (10, 11).

9. The multi-disk brake as claimed in claim 8, characterized in that the ramp unit (9) has two ramp disks (10, 11) arranged between two multi-disk packs (7, 8), and in that one ramp disk (10) can be driven in one direction and the other ramp disk (11) in the other direction for the displacement in the axial direction.

10. The multi-disk brake as claimed in claim 9, characterized in that the ramp disks (10, 11) each have a control arm (21, 22), in that the lever element (19) is arranged between the control arms (21, 22), and in that the ramp disks (10, 11) of the guide device (14) have support arms (23, 24) which are at a distance opposite one another.

11. The multi-disk brake as claimed in one or more of claims 8 to 10, characterized in that the ramp disk (10, 11) has tapering grooves (27) for partially receiving balls (26).

12. The multi-disk brake as claimed in one or more of claims 1 to 11, characterized in that the guide device (14) is non-rotatably connected to a housing (2).

13. The multi-disk brake as claimed in one or more of claims 1 to 12, characterized in that the guide device (14) has guide pins (15) fastened in the housing (2).

14. The multi-disk brake as claimed in one or more of claims 1 to 13, characterized in that the housing (2) is designed to be open toward a transmission (6) of the motor vehicle.

15. The multi-disk brake as claimed in one or more of claims 1 to 14, characterized in that the actuating mechanism/actuator (3) can be activated depending on the direction of rotation of the drive shaft (4).