DE102013007574A1 - Actuating device for arrangement between a brake pedal and a master cylinder of a motor vehicle - Google Patents

Abstract

An actuating device (2) for arrangement between a brake pedal and a master brake cylinder of a motor vehicle comprises an electrical actuating device (5) with a push rod (7) for actuating the master brake cylinder (4) and a pedal simulator (6) which is connected between the brake pedal (3) and The electrical actuating device (5) is arranged and has a penetrating element (11) which is spaced from the push rod (7) by an air gap (15), said air gap (15) in a first operating mode of the actuating device (2) when actuated of the brake pedal (2) is maintained and is overcome in a second operating mode when the brake pedal (3) engages mechanically on the master brake cylinder (4). The push rod (7) has a stop buffer (24) made of elastomer material at its end facing the penetrating element (11). This creates an actuating device (2) which is advantageous in terms of manufacture and use.

Description

The invention relates to an actuating device for the arrangement between a brake pedal and a master cylinder of a motor vehicle, comprising an electric actuator with a push rod for actuating the master cylinder and a pedal simulator, which is arranged between the brake pedal and the electric actuator and has a passage element which of the pressure rod is spaced by an air gap, said air gap is maintained in a first operating mode of the actuator upon actuation of the brake pedal and is overcome in a second operating mode with mechanical penetration of the brake pedal to the master cylinder.

For braking passenger vehicles, the driver's foot force is usually not sufficient, so that these are usually equipped with a brake booster. Brake boosters usually work with a negative pressure generated by the engine. In this case, the pressure difference between the engine pressure and the ambient pressure is used to apply in addition to the driver's foot force, an amplifying force on the piston rod of the master cylinder. With increasing vehicle mass vacuum booster with relatively large diameter are needed. Conventional brake booster have a diameter of up to 26 cm. They are therefore very bulky and restrict the space in the engine compartment for other components.

In diesel engines, modern direct-injection FSI engines or Valvetronic engines, however, there is no longer sufficient underpressure at the engine. For this reason, electric motors or negative pressure pumps driven by the internal combustion engine are used in these engines. However, these and the necessary tubing require space, increase the vehicle weight and are complex in terms of manufacturing and assembly. An alternative to this is electromechanical brake booster, which generate the actuation force on the master cylinder by means of an electric motor. Such devices can be used not only to provide an auxiliary power, but also in brake-by-wire systems for the sole provision of the actuating force.

A generic actuator is off DE 10 2009 055 721 A1 known. This comprises, in addition to an electrical actuator, a pedal simulator arranged between the same and the brake pedal. The brake system according to DE 10 2009 055 721 A1 can thus be operated in a first operating mode in which the brake pedal interacts with the pedal simulator and decoupled from the master cylinder through an air gap (brake-by-wire), and in a second operating mode in which the brake pedal via a push rod of the electric actuator mechanically engages the master cylinder to apply this force, the pedal simulator is disabled. This provides a mechanical fallback level. In order to dampen a hard impact in overcoming the aforementioned air gap in such a mechanical penetration, a damping element is attached to the corresponding passage element of the pedal simulator.

The invention is based on the object of demonstrating an improved alternative with regard to production and use.

To achieve the above object, an actuating device for arrangement between a brake pedal and a master cylinder of a motor vehicle with the features of claim 1 is proposed.

The actuating device according to the invention for the arrangement between a brake pedal and a master cylinder of a motor vehicle comprises an electric actuator with a push rod for actuating the master cylinder and a pedal simulator, which is arranged between the brake pedal and the electric actuator and a Durchgriffselement having from the push rod through an air gap is spaced, this air gap is maintained in a first mode of operation of the actuator upon actuation of the brake pedal and is overcome in a second operating mode with mechanical penetration of the brake pedal to the master cylinder. It is characterized in that the push rod has an abutment buffer made of elastomeric material at its end facing the passage element.

The integration of the stop buffer into the push rod makes mass production easier and less expensive.

Advantageous embodiments of the invention are specified in further claims.

Preferably, the stop buffer on its side facing the passage element on a curved stop surface. This allows a particularly soft response of the stop buffer.

Furthermore, the penetration element may be a recess with a rounded bottom as Form the mating surface for the stop buffer, wherein the push rod extends with the stop buffer in the recess of the punch-through element. Any inclinations can be easily absorbed and compensated.

Further, the recess may be tapered to its bottom in diameter. On the one hand this allows a normal operation while maintaining the air gap, on the other hand, in the case of a stop, a defined stop position is precisely adhered to.

According to a further advantageous embodiment of the invention, the pedal simulator is designed as a cylinder-piston arrangement. The passage element is a piston of this piston-cylinder arrangement. By forming the aforementioned recess in an end face of the piston, a particularly compact design is achieved.

Preferably, the air gap between the stop buffer and the passage element is dimensioned such that the stop buffer is effective when exceeding a certain speed of the brake pedal lever in the first operating mode. As a result, both a haptic and an acoustic improvement is achieved in normal operation when the brake pedal is operated at high speed.

According to a further advantageous embodiment of the invention, the stop buffer is molded onto an end portion of the push rod, whereby good adhesion is ensured with ease of manufacture. However, it is also possible to glue the stop buffer to the end portion of the push rod or to lock with this.

Furthermore, the push rod can form an end face with at least one recess or at least one projection, which engages positively with a corresponding contour of a stop buffer rear side. As a result, transverse forces occurring at any inclinations are better supported and thus improves the binding of the stop buffer to the push rod.

Furthermore, the stop buffer at the interface to the push rod, the outer contour of the push rod continuously continue, whereby a catching of the stop buffer is avoided.

The actuating device explained above is preferably used on a motor vehicle. Its brake system includes a brake pedal and a pedal simulator coupled to the brake pedal and also a master cylinder. The actuator is spatially arranged between the brake pedal and the master cylinder. The brake system has a first mode of operation in which the brake pedal cooperates with the pedal simulator and decoupled from the master cylinder, and a second mode of operation in which the brake pedal can force the master cylinder via the push rod and the pedal simulator is deactivated. As a result, a brake-by-wire system is realized in normal operation, which has a mechanical fallback in an emergency, for example in case of failure of the electrical actuator.

In case of failure of the electric drive is a mechanical penetration, d. H. an actuation of the master cylinder via the brake pedal by the driver by means of the push rod possible. Further, a combination operation is possible in which the operating force of the master cylinder is applied both by the force of the driver on the brake pedal and by the electric actuator.

The invention will be explained in more detail with reference to an embodiment shown in the drawing. The drawing shows in:

1 a spatial view of an actuator according to the invention with a connected master cylinder,

2 an exploded view of the arrangement 1 to illustrate the individual modules,

3 a further spatial view of the actuating device according to the invention in the installed position with respect to a bulkhead and a brake pedal,

4 a longitudinal sectional view of the actuator,

5 a detailed view of the interface between push rod and punch-through element,

6 an exploded view of the actuator,

7 a detailed view of the stop buffer,

8th a first modification of the stop buffer,

9 a second modification of the stop buffer, and in

10 a third modification of the stop buffer.

The embodiment relates to a brake system 1 for a motor vehicle, in particular a passenger vehicle. This comprises an actuating device 2 between a brake pedal 3 and a master cylinder 4 is arranged. To the master cylinder 4 is an ESP hydraulic unit of known type, not shown, connected to set a wheel pressure on the wheel brakes of the motor vehicle individually.

The actuating device 2 becomes dependent on an operation of the brake pedal 3 controlled by the driver to provide a braking force. For this purpose, the position of the brake pedal 3 detected by a position sensor. The position sensor can be designed, for example, as a rotary encoder. However, it is also possible to detect the brake pedal position by means of a linear displacement sensor. Alternatively or additionally, the operating force F of the driver on the brake pedal 3 determined by a force sensor and to control the actuator 2 be used.

The actuating device 2 includes an electrical actuator 5 for actuating the master cylinder 4 and a pedal simulator 6 between the brake pedal 3 and the electric actuator 5 is arranged.

The electric actuator 5 has a housing 5a on, located on the master cylinder 4 supported. In the case 5a runs a push rod 7 against an actuating piston 4a of the master cylinder 4 suppressed. Furthermore, the electric actuator comprises 5 an electric motor 8th as well as a snail 9 by the electric motor 8th is driven and the push rod 7 crosses. In the illustrated embodiment, the screw closes 9 with the axis of movement of the pressure element 6 an angle of 90 degrees. However, the snail can 9 also obliquely to the axis of movement of the pressure element or to the push rod 6 be employed, for example, with an angle in the range of 60 to 120 degrees. Furthermore, the electrical actuator 5 a transmission disposed in the housing 10 on, that's the snail 9 with the push rod 7 so coupled to a rotational movement of the screw 9 in a translational movement of the push rod 7 to translate. The latter causes an actuation of the actuating piston 4a of the master cylinder 4 to set a brake pressure for the ESP hydraulic unit according to the brake pedal operation.

In the illustrated vehicle brake system, the brake pedal is used 3 in normal operation (first operating mode) only as a signal generator. The driver's brake pedal 3 Applied actuation force is only used to a drive signal for the actuator via the position sensor and / or an optionally existing force sensor 2 provide. A mechanical coupling of the brake pedal 3 with the hydraulic system of the ESP hydraulic unit is in the case of an intact actuator 2 not given.

In order to facilitate the driver in a brake pedal operation, the dosage of the braking force, includes the brake system 1 the above-mentioned pedal simulator 6 with the brake pedal 3 is coupled. The pedal simulator 6 generates at a brake pedal actuation of the operation opposing resistance according to a predetermined force-displacement curve. The force-displacement characteristic curve is configured in such a way that the driver feels greater resistance as the actuating force increases. This haptic feedback correlates strongly with that via the electrical actuator 5 generated braking force and substantially corresponds to the known from conventional hydraulic vehicle brake systems brake feel.

The pedal simulator 6 is presently exemplified as a cylinder-piston arrangement, the piston as a penetration element 11 serves and with the brake pedal via a push rod 12 is coupled. However, another embodiment of the pedal simulator is also 6 possible. At the push rod 12 also employs a return spring 13 at.

The pedal simulator 6 can be used in a pure brake-by-wire configuration. In the illustrated embodiment is nevertheless on the push rod 7 allows a mechanical fallback, in case of failure of the electrical actuator 5 (second mode of operation) allows the driver's power to the master cylinder 4 to bring to action and thereby to generate a brake pressure.

The between the penetration element 11 of the pedal simulator 6 and the actuating piston 4a of the master cylinder 4 arranged push rod 7 is in normal operation when the brake pedal is pressed 3 force-free and applies the brake pedal 3 no reaction. She is at one with the actuating piston 4a of the master cylinder 4 interacting pressure spindle 14 held and points to the punch-through element 11 axially an air gap 15 on. When a brake pedal operation, the pressure spindle 14 through the electric motor 8th axially displaced so that the air gap 15 despite movement of the push rod 7 persists. If the electric motor fails 8th off, the air gap is at a brake pedal operation 15 overcome, leaving the penetration element 11 against the push rod 7 got into contact. The push rod 7 in turn presses on the actuating piston 4a of Master cylinder 4 , reducing the driver's power directly to the master cylinder 4 acts.

In order to always allow a safe reduction of the brake pressure to zero, the transmission is 10 Self-locking trained. Otherwise, in the event of a power failure during braking operation, the electric actuator would 5 remain in position during power failure and continue to build up brake pressure. Accordingly, the transmission 10 designed so that already by the hydraulic counter pressure and / or a return spring, a sufficient restoring force is built up, which is the electrical actuator 5 moves back to zero position.

The electric motor 8th may be a brushless DC motor, a three-phase motor, an asynchronous motor, a stepper motor or a conventional DC motor. Its control is via a control unit 17 , which as input the pedal travel on the brake pedal 3 which evaluates pedal force, actuation speed, vehicle speed or load state, or a combination of these quantities.

The actuating device 2 can be composed of several modules. 2 shows next to the master cylinder 4 the housing 5a the electric actuator 5 as the first module, the laterally connected electric motor 8th as the second module and also the side of the housing connected control unit 17 as the third module. The control unit 17 is on the electric motor 8th opposite side of the housing 5a the electric actuator 5 arranged. This module-like structure makes it easy to adapt to different vehicle configurations in the series by providing different variants for the respective modules. In addition, changes can be made in the individual modules without this directly affecting the other modules.

3 shows the arrangement of the actuator 2 on the vehicle, of the latter only the bulkhead 18 is shown. The housing 5a the electric actuator 5 and the electric motor 8th are on the side of the master cylinder 4 in front of the bulkhead 18 arranged. In this case, the housing is supported 5a against the bulkhead 18 from and is preferably attached to this. The housing 5a serves at the same time as a holder for the electric motor 8th and the controller 17 which are both on the outer circumference of the housing 5a are fixed. For the mechanical fallback level is in the bulkhead 18 an opening 19 provided which the actuation of the push rod 7 through the penetration element 11 allows. The pedal simulator 6 is present in relation to the bulkhead 18 on the side of the brake pedal 3 arranged, in particular between the push rod 7 and the brake pedal 3 ,

The construction of the housing 5a arranged transmission 10 is in the 4 to 6 shown. The gear 10 includes a sleeve 20 , which rotate in the housing 5a stored, but axially fixed. In the illustrated embodiment, this is a single roller bearing 21 provided between the outer circumference of the sleeve 20 and an inner peripheral surface of the housing 5a is arranged. The sleeve 20 also has a worm wheel on its outer periphery 22 on, with the snail 9 is engaged and accordingly driven by this. Furthermore, the sleeve 20 an internal thread 23 on that with the pressure spindle 14 in threaded engagement. Preferably, this is a trapezoidal thread with self-locking slope used.

Unlike the sleeve 20 is the pressure spindle 14 in the case 5a secured against rotation, but axially movable. Will the sleeve 20 set in rotation, so shifts the pressure spindle 14 depending on the direction of rotation of the sleeve 20 axially in the direction of the master cylinder 4 to or from this way. In doing so, the pressure spindle takes 14 the push rod 7 With. Preferably, the electric motor 8th so controlled that the pressure spindle 14 at least predominantly or always in contact with the actuating piston 4a remains to ensure a quick response of the brake system.

The push rod 7 extends through the pressure spindle 14 and the sleeve 20 therethrough. The latter are preferably coaxial about the push rod 7 arranged.

The push rod 7 has at her to the punch-through element 11 pointing end a stop buffer 24 made of elastomeric material and extends with this in one on the passage element 11 trained deepening 25 into it. In the present case is the depression 25 on an end face of the piston of the designed as a cylinder-piston assembly pedal simulator 6 ,

In normal operation (first operating mode) the stop buffer touches 24 the inner wall of the recess 25 not, but is from this even during a braking process through the air gap 15 spaced.

The air gap 15 must not be too large to ensure a mechanical penetration in the event of a failure of the electrical system (second mode of operation), a sufficiently short pedal travel for the then purely mechanical Applying force to the master cylinder 4 to be ensured by the driver. On the other hand, the electric motor 8th and the gearbox 10 remain compact, are the speeds of the pressure spindle 14 limited. It can therefore occur in a fast brake operation, that in normal operation, ie in the first operating mode, the penetration element 11 against the push rod 7 briefly come into contact. The stop buffer 24 Made of elastomeric material eliminates this noise and a possibly briefly felt resistance. The air gap 15 is thus dimensioned such that the stop buffer 24 only when a certain speed of the brake pedal is exceeded 3 in the first operating mode becomes effective.

A soft response of the stop buffer 24 is by one on the side of the punch-through element 11 bulging stop surface 26 achieved.

The depression 25 the Durchgriffselements 11 forms the stop buffer 24 opposite a rounded ground 27 as counter surface for the stop surface 26 of the stop buffer 24 out. In addition, the depression tapers 26 tapered towards its bottom, so that at any inclinations always a defined stop position is reached. This will jamming the push rod 7 prevented.

For the same reasons, a particularly stable connection between the stop buffer 24 and the push rod 7 be provided. The stop buffer is preferred 24 to an end portion of the push rod 7 molded. However, it can also be glued or with an end portion of the push rod 7 be locked.

In addition, between the front surface 28 the push rod 7 and the stop buffer 24 a positive engagement may be provided, as for the modified embodiments in the 9 and 10 is shown. For example, the push rod 7 on her face 28 at least one depression 28a or have at least one projection. The stop buffer back 29 is contoured correspondingly complementary, so that there is a positive engagement, which offers improved adhesion in terms of any lateral forces.

In addition, like the 7 to 10 can be removed, the stop buffer 24 at the interface to the push rod 7 the outer contour of the push rod 7 continue continuously. This results in a stepless, smooth transition that can not get caught.

In a simplified embodiment, the stop buffer without warping with a flat face as a stop surface 26 executed as in the 8th and 10 is shown.

The opposite end of the push rod 7 has a rounding 30 and extends into a recess of the actuating piston 4a into it. The bottom of the recess is as a dome 31 trained, against which the rounding 30 the push rod 7 is applied.

The master cylinder 4 opposite end of the housing 5a is through a housing cover 32 locked. The housing cover 32 is non-rotatable on the housing 5a arranged and secures the outer ring of the bearing 21 axially. On the housing cover 32 are several cones 33 provided, which in on the outer circumference of the pressure spindle 14 located axial grooves 34 engage and thus the pressure spindle 14 at a twisting relative to the housing 5a prevent.

Instead of axial grooves 34 on the outer circumference can also axial bores on the pressure spindle 14 be provided, in which the pins 33 intervention. Further, instead of the trapezoidal thread, a ball screw can be provided, which is characterized by low friction, whereby the required drive torque of the motor is reduced. However, the solution with trapezoidal thread is distinguished from that with ball screw by a significantly reduced effort and is therefore less expensive.

The invention has been explained above with reference to an embodiment. However, it is not limited to the illustrated embodiments and variants, but includes all embodiments defined by the claims.

LIST OF REFERENCE NUMBERS

1

braking system

2

actuator

3

brake pedal

4

Master Cylinder

4a

actuating piston

5

electrical actuator

5a

casing

6

pedal simulator

7

pushrod

8th

electric motor

9

slug

10

transmission

11

piston

12

pushrod

13

Return spring

14

jackscrew

15

air gap

17

control unit

18

bulkhead

19

opening

20

shell

21

roller bearing

22

worm

23

inner thread

24

buffer

25

deepening

26

stop surface

27

rounded ground

28

front

28a

deepening

29

Buffer back

30

curve

31

dome

32

housing cover

33

spigot

34

axial groove

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102009055721 A1 [0004, 0004]

Claims (10)

Actuating device ( 2 ) for arrangement between a brake pedal ( 3 ) and a master cylinder ( 4 ) of a motor vehicle, comprising: an electric actuator ( 5 ) with a push rod ( 7 ) for actuating the master cylinder ( 4 ), and a pedal simulator ( 6 ) between the brake pedal ( 3 ) and the electrical actuator ( 5 ) is arranged and a penetration element ( 11 ), which from the push rod ( 7 ) through an air gap ( 15 ), this air gap ( 15 ) in a first operating mode of the actuating device ( 2 ) upon actuation of the brake pedal ( 2 ) is maintained and in a second operating mode with mechanical penetration of the brake pedal ( 3 ) on the master cylinder ( 4 ) is overcome, characterized in that the push rod ( 7 ) at its to the penetration element ( 11 ), a stop buffer ( 24 ) made of elastomeric material. Actuating device ( 2 ) according to claim 1, characterized in that the stop buffer ( 24 ) at its to the Durchgriffselement ( 11 ) facing side a curved stop surface ( 26 ) trains. Actuating device ( 2 ) according to claim 1 or 2, characterized in that the penetration element ( 11 ) a recess ( 25 ) with a rounded bottom ( 27 ) as counter surface for the stop buffer ( 24 ) and the push rod ( 7 ) with the stop buffer ( 24 ) into the depression ( 25 ) of the penetration element ( 11 ) extends into it. Actuating device ( 2 ) according to claim 3, characterized in that the depression ( 25 ) to its bottom ( 27 ) tapers in diameter. Actuating device ( 2 ) according to claim 3 or 4, characterized in that the pedal simulator ( 6 ) is designed as a cylinder-piston arrangement and the passage element ( 11 ) is a piston of this piston-cylinder arrangement, wherein the recess ( 25 ) is formed on an end face of the piston. Actuating device ( 2 ) according to one of claims 1 to 5, characterized in that the air gap ( 15 ) is dimensioned such that the stop buffer ( 24 ) when a certain speed of the brake pedal is exceeded ( 3 ) in the first operating mode is effective. Actuating device ( 2 ) according to one of claims 1 to 6, characterized in that the stop buffer ( 24 ) to an end portion of the push rod ( 7 ) is sprayed or glued or with an end portion of the push rod ( 7 ) is locked. Actuating device ( 2 ) according to one of claims 1 to 7, characterized in that the push rod ( 7 ) an end face ( 28 ) with at least one depression ( 28a ) or at least one projection which forms a positive fit with a corresponding contour of a stop buffer rear side ( 29 ) is engaged. Actuating device ( 2 ) according to one of claims 1 to 8, characterized in that the stop buffer ( 24 ) at the interface to the push rod ( 7 ) the outer contour of the push rod ( 7 ) continuously. Brake system of a motor vehicle, comprising a brake pedal ( 3 ), a master cylinder ( 4 ) and an actuating device ( 2 ) according to one of the preceding claims.

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