DE102007016861A1 - Brake booster for use in power braking system of vehicle i.e. passenger car, has lever arrangement designed such that pedal force and auxiliary force produced at two coupling points produce brake force at third coupling point - Google Patents

Abstract

The booster has a transmission device (12) formed as a lever arrangement (14). A lever end (14.1) is coupled with a coupling rod (3) over a lever arm (L1) and a coupling point (14.4). The arrangement (14) is designed in such a manner that a pedal force produced at the point (14.4) by a brake pedal (2) and additional auxiliary force produced at another coupling point (14.5) by an energy storage unit (50) correspondingly produce a common brake force at a third coupling point (14.6). A brake force acts at a piston (21) of a main brake cylinder (20) for releasing brake pressure in the cylinder.

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 a corresponding auxiliary 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.

A conventional power brake system with an electromechanical brake booster is described for example in US Pat US Pat. No. 6,634,724 B2 described. In the described described by an electric motor driven brake booster, the rotational movement of the electric motor is converted into a translational movement to increase the braking force during operation. The conversion of the rotation into a translation takes place by means of a pinion / rack combination. The described brake booster is part of an auxiliary power brake system in which the actual braking force is generated by a summation of a pedaling force applied by the driver and an assisting force applied by the brake booster. In the described power brake system, the electric motor provides all the energy for generating the auxiliary braking force.

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 Coupling rod is coupled and via a third lever arm and a third coupling point with a piston of a master cylinder coupled, and a second end of the lever via a second Lever and a second coupling point with an energy storage element is coupled. The lever arrangement is designed so that the pedal force generated by a brake pedal at the first coupling point and generated by the energy storage element at the second coupling point additional assistant corresponding to the leverage laws at the third coupling point together generate a braking force, the acts on the piston of the master cylinder to the master cylinder build up and / or reduce a brake pressure. About the Coupling rod becomes the brake pedal with the piston of the master cylinder coupled to transmit the pedal force acting on the brake pedal. 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 store can be used to generate the additional Auxiliary power over the prior art reduced power Drive element can be used. Another advantage is that the energy spent to operate the brake system is, 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 the coupling with the brake pedal driver-dependent braking and controlled by an evaluation and control unit Drive element and the energy storage driver-independent braking To run. This allows various comfort and security features are 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 into the stoppage, a hill hold function, d. H. the vehicle will at a standstill on a mountain automatically in its current one Position, an APB function (automatic parking brake function), etc. Furthermore, it is in the event of a fault in the driver Brake booster or in the event of a power failure the coupling between the piston of the master cylinder and the Brake pedal over the coupling rod possible, the Auxiliary power brake system according to the invention only by To apply muscle power.

The Auxiliary power brake system according to the invention 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 Auxiliary power brake system, in which the brake booster according to the invention is implemented, is advantageously significantly reduced.

By the measures and refinements recited in the dependent claims Advantageous improvements of the independent claim 1 brake booster and specified in the independent claim 8 auxiliary 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 on the third. 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.

at a driver-dependent braking, the corresponding Braking force from the pedal force acting on the first coupling point and from the additional coupling point acting on the second coupling point Assisting power can be generated. The proportions of the pedal force and the additional Assistive force to the corresponding braking force can correspond with the leverage laws by moving the pivot axis of the lever assembly be set. This means that by moving the pivot axis an arbitrary gain factor for the assistant can be adjusted in relation to the pedal force. The Evaluation and control unit, for example, the currently acting Determine pedal force via corresponding sensor units and the desired corresponding auxiliary power over adjust the displacement of the pivot axis. Alternatively, at a driver-independent braking the corresponding Braking force only from acting on the second coupling point additional Assisting power can be generated. This means that the evaluation and Control unit by moving the pivot axis of the lever assembly the desired with the leverage laws desired Braking force sets.

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 third 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 from a detected via a displacement sensor on the coupling rod Activation are estimated and / or over one of a force sensor on the brake pedal or on the coupling rod detected force can be calculated. Additionally or alternatively can brake pressure by one of an angle sensor on the brake pedal estimated operating angle are estimated. Furthermore, the brake pressure can be applied directly to one in the supply lines too a fluid block and / or arranged in the master cylinder pressure sensor detected or via a displacement sensor on the master cylinder to be appreciated.

In Embodiment of the brake booster according to the invention the pivot axis is set in an 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.

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 mechanical power boost the driver operation on the piston of the master cylinder be caused. This effect is mostly during of emergency operation advantageous in which the braking force only by the Pedal force is generated.

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

Brief description of the drawings

1 shows a schematic block diagram of an auxiliary brake system according to the invention, which comprises a first embodiment of a brake booster according to the invention.

2 shows a schematic block diagram of a second embodiment of a brake booster according to the invention.

embodiments the invention

In In the drawings like reference numerals designate elements or components, which perform the same or analog functions.

How out 1 can be seen comprises an inventive power brake system 1 for a vehicle, a brake pedal 2 , a brake booster 10 and a main brake 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, the brake pedal act 2 and / or the brake booster 10 on a piston 21 of the master cylinder 20 , How out 1 can be further seen, comprises the brake booster 10 a coupling rod 3 , a transmission device 12 , 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 with the coupling rod 3 coupled and via a third lever arm L3 and a third coupling point 14.6 via a coupling stamp 23 with the piston 21 of the master cylinder 20 coupled, in the illustrated embodiment, an active axis of the first coupling point 14.4 and an effective axis of the third coupling point 14.6 lie on a plane, ie, the first and third lever arms L1 and L3 have starting from the tilting 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. 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. How farther 1 it can be seen, is the lever assembly 14 so executed that from the brake pedal 2 at the first coupling point 14.4 generated pedal force and the energy storage element 50 at the second coupling point 14.5 generated auxiliary power corresponding to the lever laws at the third coupling point 14.6 together generate a braking force, via the coupling punch 23 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.

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 threaded transmission element 16 be adjusted, that of the designed as an electric motor drive element 13 is driven to at the third coupling point 14.6 to generate a 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 third coupling point 14.6 cause receives the evaluation and control unit 11 Signals from multiple sensor units 60 . 62 . 64 . 66 and evaluate these.

In a driver-dependent braking process, the corresponding at the third coupling point 14.6 acting braking force from the first coupling point 14.4 acting pedal force and from the second coupling point 14.5 acting auxiliary power to be generated. The proportions of the pedal force and the additional auxiliary power to the corresponding braking force, 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 auxiliary power 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 assistant 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 . 66 a current brake pressure in the auxiliary 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 determined 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 one of a displacement sensor on the coupling rod 3 estimated actuating path are estimated and / or via one of a force sensor 60 at 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. Via a second sensor unit 62 can be the evaluation and control unit 11 the brake pressure in the master cylinder 20 Measure directly or via a displacement sensor on the master cylinder, the distance traveled by the piston 21 recorded, estimate the brake pressure. Via a third sensor unit 64 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. Via a fourth sensor unit 66 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: Anitblockingsystem, 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 third coupling point 14.6 from the evaluation and control unit 11 only from the second coupling point 14.5 acting additional auxiliary power 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 L2 and L3 can be varied. By changing the lever arms L2 and L3 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 arm L2 is the energy storage element 50 tethered. The other side of the rocker arm with the third lever arm L3 is on the coupling with the brake 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 L2 and L3, an amount of energy between the two systems can be moved.

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 the braking force acting on the third coupling point only from the first coupling point 14.4 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 workability during emergency operation without a return element 17 is maintained (fail operational).

The in 2 illustrated brake booster 10 ' is essentially the same as in 1 illustrated brake booster 10 so that only the differences and their effects are described in detail below. How out 2 is apparent, the in. differs 2 illustrated brake booster 10 ' thereby from the in 1 illustrated brake booster that an axis of action of a 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 are offset by a predetermined distance S = L1'-L2'.

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 S, ie the first lever arm L1 'is longer than the third lever arm L3' an additional mechanical gain of the first coupling point 14.4 ' acting pedal force on the third coupling point 14.6 ' 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. At a negative distance S, not shown, that is, the first lever arm L1 'is shorter than the third lever arm L3', the braking force of the master cylinder 20 on the brake pedal 2 strengthened. In this situation, although the driver's pedaling force is not amplified, but the Betätigungsweg is reduced (product off Force × path = constant).

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 Auxiliary power brake system, 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

• - US 6634724 B2 [0003]

Claims (10)

Brake booster for a vehicle with a coupling rod ( 3 ) for coupling a brake pedal ( 2 ) with a piston ( 21 ) of a master cylinder ( 20 ), and a transmission device ( 12 ), with the piston ( 21 ) of the 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, L1 ') and a first coupling point ( 14.4 . 14.4 ') with the coupling rod ( 3 ) and via a third lever arm (L3, L3 ') and a third coupling point ( 14.6 . 14.6 ' ) with the piston ( 21 ) of the master cylinder is coupled, 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 the lever arrangement ( 14 ) is designed so that the brake pedal ( 2 ) at the first coupling point ( 14.4 . 14.4 ' ) and the energy generated by the energy storage element ( 50 ) at the second coupling point ( 14.5 ) generated additional auxiliary force corresponding to the lever laws at the third coupling point ( 14.6 . 14.6 ' ) together generate a braking force acting on the piston ( 21 ) of the master cylinder ( 20 ) acts in the master cylinder ( 20 ) build up and / or reduce a brake pressure. 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, L3, L1 ', L3'), by a transmission element ( 16 ) is adjustable by a drive element ( 13 ), by an evaluation and control unit ( 11 ) is driven to adjust various lever arms (L1, L2, L3, L1 ', L3') to be engaged at the third coupling point ( 14.6 . 14.6 ' ) 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 in a driver-dependent braking operation, the corresponding braking force from the at the first coupling point ( 14.4 . 14.4 ' ) acting pedal force and from the at the second coupling point ( 14.5 ) acting auxiliary power can be generated, wherein the proportions of the pedal force and the additional auxiliary power at the corresponding braking force corresponding to the lever laws by moving the pivot axis ( 15 ) of the lever arrangement ( 14 ) are adjustable. Brake booster according to one of claims 1 to 3, characterized in that in a driver-independent braking operation, the corresponding braking force only from the at the second coupling point ( 14.5 ) acting auxiliary power can be generated, wherein the corresponding braking force corresponding to the lever laws by moving the pivot axis ( 15 ) of the lever arrangement ( 14 ) is adjustable. Brake booster according to one of claims 1 to 4, characterized in that in an emergency operation, 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 at the first coupling point ( 14.4 . 14.4 ' ) 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 active axis of the first coupling point ( 14.4 ) and the axis of action of the third coupling point ( 14.6 ) 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 (S = L1'-L2 '). Power assist brake system for a vehicle with a brake pedal ( 2 ), a brake booster ( 10 . 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 ) and / or the brake booster ( 10 . 10 ' ) for establishing or reducing a brake pressure on a piston ( 21 ) of the master cylinder ( 20 ), characterized in that the brake booster ( 10 . 10 ' ) is executed according to one of claims 1 to 7. Auxiliary 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 auxiliary power brake system ( 1 ), wherein the pivot axis ( 15 ) of the lever arrangement ( 14 ) via the drive element ( 13 ) driven transmission element ( 16 ) corresponding to that of the evaluation and control unit ( 11 ) is adjustable to at the third coupling point ( 14.6 . 14.6 ' ) to generate a corresponding braking force and the brake pressure in the auxiliary power brake system ( 1 ) increase or decrease. Auxiliary 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 over a the coupling rod ( 3 ) Sensing displacement sensor ( 60 ) and / or force sensor ( 60 ) and / or the 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 ( 62 ) and / or through at least one in a supply line to a fluid block ( 30 ) arranged second pressure sensor ( 64 . 66 ) directly and / or via one on the master cylinder ( 20 ) arranged the piston ( 21 ) appraises sensory displacement sensor.