DE102007016867A1 - Brake booster for vehicle, has transfer device implemented as lever arrangement, where brake pedal is mechanically decoupled by piston of main brake cylinder during mode of operation - Google Patents

Abstract

The brake booster (10) has a transfer device (12) implemented as a lever arrangement (14). A lever end (14.1) is coupled with a piston (21) of a main brake cylinder (20) over a lever arm (L1) and a coupling point (14.4). Another lever end (14.2) is coupled with an energy store element (50) over another lever arm (L2) and another coupling point (14.5). A brake pedal (2) is mechanically decoupled by the piston of the main brake cylinder during a mode of operation. An independent claim is also included for an external power brake system.

Description

State of the art

The Invention is based on a brake booster for a vehicle according to the preamble of the independent claim 1 and from a corresponding power-brake system for a vehicle according to the preamble of the independent claim 8th.

By the definition brake-by-wire braking system becomes a so-called power-assisted braking system described in which without a direct transfer of Muscle force of the driver on the braking torque generating element with a brake booster the required braking torque is produced. Braking systems in which the foot force in addition to an amplifying force generated by a brake booster are used, so-called auxiliary power brake systems that are in Passenger car sector among the most widely used brake systems.

In the published patent application WO 2005/014351 A1 is a so-called brake-by-wire brake system described. The described brake system is actuated by a brake actuation unit which comprises a brake booster designed as a vacuum brake booster, a master brake cylinder connected downstream of the brake booster, means for detecting a driver deceleration request and a pedal travel simulator. The brake booster can be operated depending on the driver by means of a brake pedal as well as by means of an electronic control unit, wherein means are present which decouple a force-transmitting connection between the brake pedal and the brake booster during the brake-by-wire mode. The pedal travel simulator simulates a force acting on the brake pedal de restoring force during the brake-by-wire mode, wherein the pedal travel simulator during the brake-by-wire mode in the decoupling of the force-transmitting connection between the brake pedal and the brake booster is switchable and can be switched off outside the brake-by-wire mode. The switching on and off of the pedal travel simulator is performed by electromechanical, electro-hydraulic or pneumatic switching means.

Disclosure of the invention

Of the inventive brake booster for a vehicle having the features of the independent claim 1 has the advantage that a transmission device is designed as a lever assembly, wherein a first end of the lever over a first lever arm and a first coupling point with a Piston of a master cylinder is coupled, and a second Lever end via a second lever arm and a second Coupling point is coupled to an energy storage element. While a first mode, preferably a break-by-wire mode, generates the energy storage unit via the transfer device, that of an evaluation and control unit corresponding to the Hebelgesetzen is controlled, at the first coupling point a braking force, which acts on the piston of the master cylinder to the master cylinder build up and / or reduce a brake pressure. While the first mode is coupled to a pedal simulator Brake pedal mechanically decoupled from the piston of the master cylinder. In addition, the transmission device for brake booster of a drive element, preferably an electric motor driven. Due to the lever arrangement according to the invention and the use of the energy storage can be used to generate the braking force a performance reduced compared to the prior art Drive element can be used. Another advantage is that the energy needed to operate the braking system is used, partially returned to the energy storage can be. The energy store can be used, for example, as a helical spring, Torsion bar spring, elastomer element, etc. are executed.

Of the inventive brake booster can over Driver-dependent pedal simulator coupled to the brake pedal Capture and detect braking requests and about the controlled by an evaluation and control unit drive element and the energy storage both driver-dependent and Run driver-independent braking. Thereby can have different comfort and security features be implemented, such as a brake assist function, an ACC (Adaptive Cruise Control) function, d. H. an adaptive Cruise control function, a soft-stop function, d. H. a reduction of the braking pressure during the transition to standstill, a hill hold function, d. H. the vehicle is at a standstill automatically held in its current position on a mountain, an APB (Automatic Park Brake) function, a driver independent Emergency brake function etc.

The Inventive power brake system for a vehicle having the features of the independent claim 8 has the advantage that due to the reduced power consumption of the brake booster according to the invention also the power consumption of the invention Fremdkraftbremssystems, in which the brake booster according to the invention is implemented, is advantageously significantly reduced.

By the in the dependent claims listed measures and developments are advantageous improvements of the independent claim 1 brake booster and specified in the independent claim 8 power-brake system possible.

Especially It is advantageous that a pivot axis of the lever arrangement, the The starting point of the lever arms is, by a transmission element is adjustable. The transmission element becomes the setting driven by various lever arms of the drive element, the is controlled by an evaluation and control unit. By the attitude of different lever arms can at the first coupling point Different braking forces are generated on the piston the master cylinder act. The drive element and the transmission element Can be considered any drive-gearbox combination be executed, which is capable of the pivot axis to adjust the lever assembly. The drive element can, for example be executed as an electric motor and the transmission element can be used as translation-translation gearbox, rotational-translation gearbox, be executed as a threaded drive, etc. The lever arrangement For example, may include a rocker arm over the pivot axis designed as a tilting axis is tilted.

In Embodiment of the brake booster according to the invention is the brake pedal with the pedal simulator and a coupling rod connected, the front side during the first mode by a predetermined distance mechanically from a third Kopp ment point is decoupled at the first end of the lever. The pedal simulator detects during the first mode and a driver-dependent braking a deceleration request on the brake pedal and determines a corresponding pedal force and directs the detection and / or Determination result to the evaluation and control unit on which the transmission device for generating the corresponding Braking force that corresponds to the determined pedal force. moreover The pedal simulator generates a corresponding haptic feedback and outputs it to the brake pedal. In a driver-independent braking process the evaluation and control unit receives the corresponding Specifications of other vehicle systems and provides the appropriate braking force at the first coupling point via the transmission unit one. The height of the braking force acting on the first coupling point can correspond to the leverage laws by moving the Swivel axis of the lever assembly can be adjusted. That means, by shifting the pivot axis any gain factor for the external force is adjusted in relation to the pedal force can be or any braking force according to the Presets can be set by other vehicle systems. The Evaluation and control unit, for example, the currently acting Determine pedal force via corresponding sensor units and the desired corresponding foreign force on adjust the displacement of the pivot axis.

In further embodiment of the brake booster according to the invention the coupling rod is designed so that this during a second mode, preferably an emergency mode, the predetermined Distance overcomes, leaving the front side of the coupling rod at the third coupling point is applied to the brake pedal To transmit pedal force to the piston of the master cylinder. During the second mode is the pedal simulator deactivated and / or bypassed. That's it the driver in the event of a malfunction of the brake booster or in the event of a power failure, through the coupling between the piston of the master cylinder and the brake pedal the coupling rod, the power brake system according to the invention to operate only by muscle power. The pivot axis can be set during emergency operation so that the Action axis of the second coupling point on a plane with the pivot axis is set so that the corresponding braking force only from the am first coupling point acting pedal force is generated. While of emergency operation, the pivot axis, for example, over a return element to the plane of the axis of action of the second Coupling point set. The reset element can, for example designed as a coil spring, torsion bar spring, elastomer element, etc. become.

additionally or alternatively, the evaluation and control unit during a brake slip control operation and / or a brake pressure control operation via at least one sensor unit a current brake pressure in the auxiliary power brake system determine and the pivot axis of the lever assembly over the drive element driven by the transmission element according to the determined by the evaluation and control unit Adjust brake pressure. As a result, at the first coupling point a corresponding braking force can be generated and the current brake pressure in the brake system can be increased or decreased. This allows in particular a reduction of the form in brake slip control operations, creating a return capacity an ABS / ESP return pump can be reduced can and therefore an ABS / ESP pump motor with a reduced power can be used.

The evaluation and control unit determines the brake pressure, for example, from a single sensor signal or from a combination of several sensor signals. The built-up brake pressure can, for example via the pedal simulator and / or estimated from an actuating travel detected via a displacement sensor on the coupling rod and / or calculated by a force detected by a force sensor on the brake pedal or on the coupling rod. Additionally or alternatively, the brake pressure can be estimated by an operating angle detected by an angle sensor on the brake pedal. Furthermore, the brake pressure can be detected directly at a pressure sensor arranged in the supply lines to a fluid block and / or in the master brake cylinder, or can be estimated via a travel sensor on the master brake cylinder, which detects the distance traveled by the piston.

In further embodiment of the brake booster according to the invention can the axis of action of the first coupling point and the axis of action of the third coupling point lie on one level. Alternatively you can the axis of action of the first coupling point and the axis of action of the third Coupling point are parallel to each other and by a predetermined distance be arranged offset. By the offset of the axis of action of Coupling rod to the axis of action of the piston of the master cylinder can be an additional power amplification of the driver's operation be caused on the piston of the master cylinder. This Effect is especially beneficial during emergency operation, in which the braking force is generated only by the pedal force.

Advantageous, Embodiments of the invention described below are shown in the drawings.

Brief description of the drawings

The single figure shows a schematic block diagram of an inventive Fremdkraftbremssystems, which is an embodiment of an inventive Includes brake booster.

embodiments the invention

As can be seen from the single figure, comprises an inventive power-braking system 1 for a vehicle, a brake pedal 2 , a brake booster 10 and a master cylinder 20 with a fluid container 22 which is used as a surge tank. About the master cylinder 20 and a fluid block 30 can have multiple wheel brakes 42 . 44 . 46 . 48 be controlled with a predetermined brake pressure. To build up or reduce a brake pressure acts during a first mode, preferably a break-by-wire mode, the brake booster 10 on a piston 21 of the master cylinder 20 and during a second mode, preferably an emergency mode, the brake pedal acts 2 on the piston 21 of the master cylinder 20 ,

As can also be seen from the figure, the brake booster according to the invention comprises 10 a pedal simulator 4 with the brake pedal 2 coupled, a transmission device 12 that with the piston 21 of the master cylinder 20 is coupled, a drive element 13 , which is preferably designed as an electric motor, and an energy storage 50 which is designed, for example, as a helical spring, torsion bar spring, elastomer element, etc. The transmission device 12 is designed as a lifting gear and includes a rocker arm 14 , a transmission element 16 , a pivot axis designed as a tilt axis 15 and a return element 17 , An upper rocker arm end 14.1 is via a first lever arm L1 and a first coupling point 14.4 via a coupling stamp 23 with the piston 21 of the master cylinder 20 coupled. A lower rocker arm end 14.2 is via a second lever arm L2, which is also from the tilt axis 15 goes out, and a second coupling point 14.5 via a coupling element 52 with the energy storage element 50 coupled. In addition, the brake pedal 2 with a coupling rod 3 connected, whose front side 3.1 during the first loading mode by a predetermined distance 5 mechanically from a third coupling point 14.6 at the upper rocker arm end 14.1 is decoupled, wherein the third coupling point 14.6 one from the pivot axis 15 outgoing third lever arm L3 has.

During the first mode, the pedal simulator detects 4 in a driver-dependent braking a deceleration request on the brake pedal 2 determines a corresponding pedal force and / or a corresponding pedal travel and passes the detection and / or determination result to the evaluation and control unit 11 Next, which is the transmission device 12 to generate the correspondingly increased pedal force. In addition, the pedal simulator generates 4 a corresponding haptic feedback and gives them to the brake pedal 2 for feedback to the driver. About through the transmission element 16 adjustable pivot axis designed as tilt axis 15 the lever arrangement 14 can be the evaluation and control unit 11 set different lever arms L1, L2 to correspond with the lever laws on the energy storage element 50 at the second coupling point 14.5 generated external force at the first coupling point 14.4 to generate a corresponding braking force on the piston 21 of the master cylinder 20 acts to be in the master cylinder 20 build up and / or reduce a brake pressure. In a driver-independent braking process provides the evaluation and control unit 11 over the transmission device 12 a predetermined by a vehicle system braking force at the first coupling point 14.4 one on the piston 21 of the master cylinder 20 works in the Master Cylinder 20 build up and / or reduce a brake pressure.

During a second mode of operation, preferably an emergency mode, the coupling rod overcomes 3 the predetermined distance 5 so the front side 3.1 the coupling rod 3 at the third coupling point 14.6 with the third lever arm L3 is applied to the brake pedal 2 generated pedal force on the coupling punch 23 on the piston 21 of the master cylinder 20 transferred to. During the second mode is the pedal simulator 4 deactivated and / or bypassed. In the illustrated embodiment are an axis of action of the first coupling point 14.4 and an effective axis of the third coupling point 14.6 on one level, ie the first and third lever arms L1 and L3 point from the tilt axis 15 which the tipping point 14.3 of the rocker arm 14 via a support element 15.1 pretending to be the same length.

The tilt axis 15 of the rocker arm 14 , which is the starting point of the various lever arms L1, L2 L3, can by a designed as a screw transmission element 16 be adjusted, that of the designed as an electric motor drive element 13 is driven to at the first coupling point 14.4 to generate the desired braking force on the piston 21 of the master cylinder 20 acts. For controlling the drive element designed as an electric motor 13 and for setting different lever arms L1, L2, L3, the different corresponding braking forces at the first coupling point 14.4 cause receives the evaluation and control unit 11 Signals from the pedal simulator 4 and / or multiple sensor units 60 . 62 . 64 and / or other vehicle systems and evaluates them.

In a driver-dependent braking process, the corresponding at the first coupling point 14.4 acting braking force from the at the second coupling point 14.5 acting external force of the energy storage element 50 be generated. The size of the corresponding braking force can be the evaluation and control unit 11 Corresponding to the leverage laws by moving the tilt axis 15 of the rocker arm 14 to adjust. The evaluation and control unit 11 For example, the currently acting pedal force via a first sensor unit 60 determine and the desired corresponding external force on the displacement of the tilt axis 15 to adjust. Thus, the evaluation and control unit 11 by moving the tilt axis 15 set any gain factor for the external force in relation to the pedal force. Additionally or alternatively, the evaluation and control unit 11 during a brake slip control operation and / or a brake pressure control operation via at least one sensor unit 60 . 62 . 64 a current brake pressure in the power brake system 1 determine and the tilt axis 15 of the rocker arm 14 Adjust according to the determined brake pressure to increase or reduce the current brake pressure.

The evaluation and control unit 11 determines the brake pressure, for example, from a single sensor signal or from a combination of several sensor signals. The built-up brake pressure can, for example via the pedal simulator 4 be determined and / or via one of a displacement sensor on the coupling rod 3 estimated actuating path are estimated and / or via one of a force sensor on the coupling rod 3 calculated pedal force are calculated. Additionally or alternatively, the brake pressure may be from one of an angle sensor on the brake pedal 2 estimated operating angle are estimated. About a sensor unit 60 can the evaluation and STEU ereinheit 11 the brake pressure in the master cylinder 20 measure directly or via a displacement sensor on the master cylinder 20 , which is the distance traveled by the piston 21 recorded, estimate the brake pressure. About a sensor unit 62 can be the evaluation and control unit 11 the brake pressure in a first brake circuit, the wheel brakes 42 and 44 includes direct measuring. About a sensor unit 64 can be the evaluation and control unit 11 the brake pressure in a second brake circuit, the wheel brakes 46 and 48 includes direct measuring. The through the evaluation and control unit 11 performed adjustment of the brake pressure allows a form for brake slip control operations and / or brake pressure control operations can be reduced, for example, the fluid block 30 when performing ABS / ESP functions (ABS: Antilock Braking System, ESP: Electronic Stability Program). As a result, a return flow of an ABS / ESP return pump can be reduced and thus an ABS / ESP pump motor with a reduced power can be used.

In a driver-independent braking operation, ie during an ACC function, a hill hold function, an APB function, etc., the corresponding braking force at the first coupling point 14.4 from the evaluation and control unit 11 from the second coupling point 14.5 acting external force generated. Here is the evaluation and control unit 11 the desired braking force without influence of the driver corresponding to the lever laws by moving the tilting axis 15 of the rocker arm 14 one.

By adjusting the tilting axis 15 the lever arms L1 and L2 can be varied. By changing the lever arms L1 and L2 are due to the lever law on the rocker arm 14 connected systems. On one side of the rocker arm 14 with the second lever L2 is the energy storage element 50 tethered. The other side of the rocker arm with the first lever arm L1 is above the coupling punch 23 with the master cylinder 20 connected. Both systems, ie energy storage element 50 and master cylinder 20 , provide a force-displacement characteristic, and the adjustment of the lever arms L1 and L2 can shift an amount of energy between the two systems.

In case of failure of the drive element 13 , ie during an emergency operation, the tilting axis 15 with the axis of action of the energy storage element 50 through a return element 17 , which is designed here as a return spring, set to a plane. This means that the second lever arm L2 = 0. During emergency operation and the displacement of the tilting axis 15 to L2 = 0, the driver can use the mechanical connection between the brake pedal 2 and the piston 21 of the master cylinder 20 act directly on this, so that at the first coupling point 14.4 acting braking force only from the third coupling point 14.6 acting pedal force is generated. Since the first and third lever arms L1 and L3 are the same length, the braking force corresponds to the pedal bar force. The position of the tilt axis 15 during emergency operation is shown with two dotted lines. Alternatively, the transmission device 12 be executed so that the ability to work during emergency operation without a return element 17 is maintained (fail operational).

In an alternative embodiment, not shown, an effective axis of the first coupling point 14.4 with the first lever arm L1 and the axis of action of the third coupling point 14.6 with the third lever arm L3 are parallel to each other and arranged offset by a predetermined distance from each other.

By the offset of the axis of action of the coupling rod 3 and the axis of action of the piston 21 of the master cylinder 20 and the offset of the first coupling point caused thereby 14.4 and the third coupling point 14.6 can at a positive distance, ie the third lever arm L3 is longer than the first lever arm L1, an additional mechanical gain of the third coupling point 14.6 acting pedal force on the first coupling point 14.4 on the piston 21 acting braking force can be achieved. This effect is particularly advantageous during emergency operation, ie when the tilt axis 15 is located in the dash-dotted position shown.

By the reduced power consumption of the invention Brake booster, the lever assembly and a Energy storage includes, and the power consumption of the invention Fremdkraftbremssystems, in which the inventive Brake booster is implemented in advantageous Be significantly reduced.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• WO 2005/014351 A1 [0003]

Claims (10)

Brake booster for a vehicle with a pedal simulator ( 4 ), with a brake pedal ( 2 ) and a transmission device ( 12 ), with the piston ( 21 ) of a master cylinder ( 20 ) and for the brake booster of a drive element ( 13 ), characterized in that the transmission device ( 12 ) as a lever arrangement ( 14 ), wherein a first end of the lever ( 14.1 ) via a first lever arm (L1) and a first coupling point ( 14.4 ) with the piston ( 21 ) of the master cylinder ( 20 ) and a second lever end ( 14.2 ) via a second lever arm (L2) and a second coupling point ( 14.5 ) with an energy storage element ( 50 ), wherein during a first mode, preferably a break-by-wire mode, the energy storage unit ( 50 ) via the transmission device ( 12 ), by an evaluation and control unit ( 11 ) is controlled corresponding to the lever laws, at the first coupling point ( 14.4 ) generates a braking force acting on the piston ( 21 ) of the master cylinder ( 20 ) acts in the master cylinder ( 20 ) to build up and / or reduce a brake pressure, the brake pedal ( 2 ) during the first mode of operation mechanically from the piston ( 21 ) of the master cylinder ( 20 ) is decoupled. Brake booster according to claim 1, characterized in that a pivot axis ( 15 ) of the lever arrangement ( 14 ), the starting point of the lever arms (L1, L2), by a transmission element ( 16 ) adjustable by the drive element ( 13 ), by an evaluation and control unit ( 11 ) is driven to adjust various lever arms (L1, L2) to be at the first coupling point ( 14.4 ) to generate the corresponding braking force acting on the piston ( 21 ) of the master cylinder ( 20 ) acts. Brake booster according to claim 1 or 2, characterized in that the brake pedal ( 2 ) with the pedal simulator ( 11 ) and a coupling rod ( 3 ) whose end face ( 3.1 ) during the first mode by a predetermined distance ( 5 ) mechanically from a third coupling point ( 14.6 ) at the first end of the lever ( 14.1 ) is decoupled, wherein the pedal simulator ( 4 ) during the first mode, a deceleration request on the brake pedal ( 2 ) and determines a corresponding pedal force and the detection and / or determination result to the evaluation and control unit ( 11 ), which transmits the transmission device ( 12 ) to generate the corresponding braking force drives, and wherein the pedal simulator ( 4 ) generates a corresponding haptic feedback and to the brake pedal ( 2 ). Brake booster according to claim 3, characterized in that the coupling rod ( 3 ) during a second mode, preferably an emergency mode, the predetermined distance ( 5 ) overcomes, so that the front side ( 3.1 ) of the coupling rod ( 3 ) at the third coupling point ( 5 ) is applied to the brake pedal ( 2 ) generated pedal force on the piston ( 21 ) of the master cylinder ( 20 ), the pedal simulator ( 4 ) is disabled and / or bypassed during the second mode. Brake booster according to claim 4, characterized in that during the second mode, the pivot axis ( 15 ) is set so that the axis of action of the second coupling point ( 14.5 ) on a plane with the pivot axis ( 15 ) is set, so that the corresponding braking force only from the third coupling point ( 14.6 ) acting pedal force is generated. Brake booster according to claim 5, characterized in that the pivot axis ( 15 ) via a return element ( 17 ) to the plane of the axis of action of the second coupling point ( 14.5 ) is set. Brake booster according to one of claims 1 to 6, characterized in that the axis of action of the third coupling point ( 14.6 ) and the axis of action of the first coupling point ( 14.4 ) lie on a plane or that the axis of action of the first coupling point ( 14.4 ) and the axis of action of the third coupling point ( 14.6 ) are parallel to each other and offset by a predetermined distance. Power-assisted braking system for a vehicle with a brake pedal ( 2 ), a pedal simulator coupled to the brake pedal, a brake booster ( 10 ) and a master cylinder ( 20 ), via which at least one wheel brake ( 42 . 44 . 46 . 48 ) is controllable with a predeterminable brake pressure, wherein the brake pedal ( 2 ) or the brake booster ( 10 ) for establishing or reducing a brake pressure on a piston ( 21 ) of the master cylinder ( 20 ), characterized in that the brake booster ( 10 ) is executed according to one of claims 1 to 7. External power brake system according to claim 8, characterized by at least one sensor unit ( 60 . 62 . 64 . 66 ), by means of which the evaluation and control unit ( 11 ) the brake pressure in the power-operated braking system ( 1 ), wherein the pivot axis ( 15 ) of the lever arrangement ( 14 ) via the drive element ( 13 ) driven transmission element ( 16 ) in accordance with that of the evaluation and control unit ( 11 ) is adjustable to the first coupling point ( 14.4 ) to generate a corresponding braking force and the brake pressure in Power-assisted braking system ( 1 ) increase or decrease. Foreign power brake system according to claim 8 or 9, characterized in that the evaluation and control unit ( 11 ) determines the brake pressure from a single sensor signal and / or from a combination of a plurality of sensor signals, wherein the evaluation and control unit ( 11 ) the brake pressure via a pedal simulator ( 4 ) and / or a coupling rod ( 3 ) Sensing position sensor and / or force sensor and / or a brake pedal ( 2 ) estimates and / or calculates the sensed angle sensor, and / or the brake pressure through one of the master cylinder ( 20 ) arranged first pressure sensor ( 60 ) and / or through at least one in a supply line to a fluid block ( 30 ) arranged second pressure sensor ( 62 . 64 ) directly and / or via one on the master cylinder ( 20 ) arranged the piston ( 21 ) appraises sensory displacement sensor.