DE112009005536B3 - Method for controlling an electromotive brake booster, braking system - Google Patents

Abstract

The invention relates to a method for controlling an electromotive brake booster, in which the master brake cylinder or tandem master cylinder (5) is driven by an electric motor (11, 12) comprising the steps: a. Detecting a piston stroke of the master cylinder or tandem master cylinder, wherein the piston stroke detected by a rotary encoder of the electric motor; b. Detecting a stroke of a brake operating device; c. Determining a path difference based on the detected piston travel and the detected stroke of the brake actuator; d. Using the path difference to control the electromotive brake boost

Description

• The invention relates to a method for controlling an electromotive brake booster according to claim 1 and to a brake system according to claim 11.
• State of the art
• The effectiveness of the active safety features of ABS, and ESP in particular, is so great that it will soon be required by law in the US and the EU. Great efforts are made to reduce the effort. According to the prior art, various solutions are known which are labor-reducing.
• A first solution consists in the integration of pressure regulation and brake booster, as it from the DE 10 2005 018 649 A1 is known. This system is based on a travel simulator with additional functions and actuators for failure in case of failure of the drive. This requires a corresponding effort.
• A second solution consists in the reduction of the valve effort by a multiplex operation. The DE 34 40 972 A1 describes a hydraulic brake booster BKV, in which the pressure control takes place by means of the THZ with corresponding valves in multiplex mode. This system does not meet the high dynamic requirements, so the switching times are too high. In addition, the noise when switching the valves are too high. The same applies to the dynamics of a pneumatic system as it is from the DE 38 43 159 A1 or DE 39 08 062 A1 is already known.
• The DE 10 2005 018 649 A1 describes an electromotive multiplex system with high dynamics as a so-called twin and tandem solution with displacement simulator. So that no pedal reaction takes place in ABS operation, an idle stroke between the pedal and the drive device is provided. The disadvantage here is that in case of failure of the drive an additional pedal travel is necessary.
• From the FR 2 860 474 A1 Further, an electric motor brake booster is known in which an electric motor via a spindle regulates a brake force assisting force. The brake pedal acts via a pedal plunger on the piston of the brake booster. Based on the force applied to the piston by the brake pedal, the power assistance to the electric motor is adjusted by means of the spindle drive. The force measurement to determine the necessary brake assist has turned out to be impractical.
• Various brake booster are from the DE 10 2006 050 277 A1 . DE 195 00 544 A1 . DE 42 29 042 A1 . US 5,758,930 A . EP 0 284 718 A2 and DE 4 327 206 A1 known.
• The DE 10 2004 050 103 A1 describes a brake booster in which a pedal via a linkage and a spring element mechanically acts on the pistons of a tandem master cylinder. A control of an arranged electric motor drive is based on a force transmitter and a pressure sensor.
• The configuration of DE 10 2004 050 103 A1 is expensive. Furthermore, the achieved braking characteristics is suboptimal.
• Starting from the DE 10 2004 050 103 A1 It is an object of the present invention to provide an improved method for controlling an electric motor brake booster.
• This object is achieved by a method according to claim 1 and by a brake system according to claim 11.
• a. Erfassen eines Kolbenwegs des Hauptbremszylinders oder Tandem-Hauptbremszylinders, wobei der Kolbenweg über einen Drehwinkelgeber des Elektromotors erfasst wird;
• b. Erfassen eines Hubs der Bremsbetätigungseinrichtung;
• c. Bestimmen einer Wegdifferenz (Δh) zwischen Kolben und Betätigungseinrichtung, basierend auf dem erfassten Kolbenweg (sK) und dem erfassten Hub der Bremsbetätigungseinrichtung;
• d. Verwenden der Wegdifferenz (Δh) zur Steuerung der elektromotorischen Bremskraftverstärkung.
In particular, the object is achieved by a method for controlling an electromotive brake booster, in which the master cylinder or tandem master cylinder is driven by an electric motor, wherein a brake actuator in the normal braking operation force-supporting acts on the spindle and / or a piston of the brake booster. According to the invention, the method comprises the steps:
• a. Detecting a piston stroke of the master cylinder or tandem master cylinder, wherein the piston stroke is detected via a rotary encoder of the electric motor;
• b. Detecting a stroke of the brake operating device;
• c. Determining a path difference (Δh) between the piston and actuator based on the detected piston travel (sK) and the detected stroke of the brake actuator;
• d. Using the path difference (Δh) to control the electromotive brake boost.
• When using the described, in particular strong, spring between the drive and the brake actuator, the stroke of the brake actuator or the pedal stroke is greater than the piston travel, which is detected by the motor with rotary encoder. This path difference can be used for braking force control or amplification, which results in a considerably simpler control. Advantageously, the sensor tolerances, z. B. different offset voltages normalized by a small idle stroke between Actuating device and drive is installed and z. B. when changing the voltage of Pedalhubgebers this position serves as a basis. Another possibility is that during commissioning or service of the system, the brake pedal is actuated until it moves the spindle and thus the rotor. The movement is measured by means of the rotation angle sensor. At this position, an adjustment of the sensor voltages or corresponding digital values takes place.
• For pressure control, a pressure transducer is provided in the pressure rod circuit, which together with the piston travel serves to determine the pressure volume characteristic. This characteristic is the basis for accurate pressure control. To further simplify the system, in particular for ABS, the motor current can also be detected via a shunt, which is proportional to the engine torque and thus pressure. This measurement or the pressure can also be used for the plausibility monitoring of the sensor signals, so that it is possible to dispense with redundant sensors.
• Below, various possible embodiments of the brake system according to the invention are explained in more detail by way of example with reference to drawings.
• Show it:
• 1 Two possible embodiments of a brake system according to the invention;
• 2 third possible embodiment of a brake system according to the invention;
• 3 fourth possible embodiment of a brake system according to the invention;
• 3a Cross section through the section xx in 3 ;
• 4 fifth possible embodiment of a brake system according to the invention with a clutch for decoupling the HZ piston and the brake actuator for the unamplified brake pressure build-up in case of failure;
• 4a : Detail of the coupling acc. 4 ;
• 5 : Brake pressure P, sensor voltage U, piston stroke s _K and pedal stroke S _P with suspension;
• 5a : Pedal force and piston force over the pedal stroke s;
• 5b : Brake pressure P, sensor voltage U, piston travel s _K and pedal stroke S _P with suspension in the event of a brake circuit failure;
• The 1 shows the basic structure of the brake system according to the invention consisting of HZ or THZ 5 , EC motor with stator 11 and rotor 12 , Spindle 13 to drive the push rod piston 24 over the pestle 21 and a rotary encoder 4 for determining the position of the push rod piston 24 and the detection of the rotor position and the piston travel.
• Receives the piston 24 the control command to build a certain pressure, it takes place on the previously recorded via piston stroke and pressure measurement and stored in a map pressure volume curve, the corresponding piston movement via the rotary encoder 4 with appropriate pressure in the brake circuits. For simplified systems, eg. B. ABS, can also be a necessary anyway for the engine control shunt 26 for current measurement of the control 25 used. Following a brief, constant pressure, which is usually the case during braking, the correlation comparison takes place on the basis of new measured data with the stored map data. In the event of a deviation, the pressure volume characteristic curve for each wheel brake is recorded once again at a later vehicle standstill and the map is corrected. Is the deviation significant, z. B. on a wheel cylinder, the note is to visit the workshop.
• The pressure generated in the HZ or THZ passes over the lines 6 and 7 of push rod piston and floating piston via the 2/2 solenoid valves 8a to 8d to the wheel cylinders 9a to 9d , Here, the dimensioning of the flow resistance for the multiplexing process in the pipes and valves is of great importance. In addition, the vote of the switching and switching times is crucial. This is described in detail in further applications of the applicant and in detail not subject of this invention.
• When the brake pedal is pressed 16 this works over the pedal ram 16a on the actuator 14 and this on the spindle 13 , In the lower half of the picture, an idle stroke Δs is shown. When the brake pedal is not pressed 16 raise the spring 17 the transmission device 14 by the idle stroke Δs from the spindle 13 from. The idle stroke Δs must be overcome at each braking until the collar of the transmission device 14 on the spindle 13 meets. In this solution, the drive (spindle) acts on the transmission device 14 directly on the brake pedal 16 , which can interfere with the pressure reduction in ABS and corresponding rapid piston movement by the shock. The brake booster here takes place via a not shown force sensor as in the DE 10 2004 050 103 A1 is described. The return spring 17 between spindle 13 and transmission equipment 14 pushes it onto a stop in the housing 15 ,
• A significant reduction in the impact is achieved by a solution, as shown in the upper half of the picture. Here, a strong compression spring acts 20 over a disc 18 on the spindle 13 , For assembly reasons, this disc 18 via a circlip 19 fixed. The feather 20 is linear or degressive for a pedal force or bar force with BKV function for a maximum pressure of e.g. B. 200 bar and has a spring stroke of 4-6 mm. The feather 20 is designed in proportion to the rod force and transmits this force to the spindle 13 , in addition, according to the selected BKV gain, the adjusting force of the engine 11 . 12 acts. Both forces together make up the force acting on the piston. If there is a quick piston return when the pressure is lowered for the ABS control, it acts via the spring 20 muffled on the pedal. A 10 bar pressure reduction in the control cycle corresponds to approx. 0.5 mm 10% of the spring travel in a mid-range vehicle.
• Thus, the pedal stroke corresponding to this stroke is greater than the piston stroke. The feather 20 can also be slightly biased for a corresponding pedal characteristic. This can use different strokes for brake booster, in that the pressure is proportional to the differential travel. This path is taken from the signals of pedal stroke sensor 22 and piston travel won. The piston travel can via the rotation angle sensor 4 be determined. The brake pressure is controlled via the piston travel based on the pressure volume characteristic. The brake control device 16 . 16a . 14 is permanently on the spring during braking 20 in contact with the drive. According to the desired gain is from the engine via the spindle 13 the corresponding force on the piston 24 transmitted, so that pedal force and amplifier power results in the piston pressure proportional to the pressure. The spindle force is transmitted via a movably mounted plunger 21 on the push rod piston 24 transfer. Here is the plunger 21 both to the push rod piston 24 as well as to the spindle 13 coupled, so that high pressure gradients can be realized even at low pressures. The plunger has the task of the possible offset of the spindle 13 and impact of the ball screw gear not on the push rod piston 24 transferred to. The spindle torque support 27 runs in a groove of the housing, preferably with good sliding properties, according to the piston stroke. The torque support is used at the same time as a stop, since the THZ return springs on the spindle 13 act and in addition to the piston return still have the task of engine reset.
• The piston or drive return is via the motor. In order to reduce an additional load of the ball screw with a faulty return and a hard stop, is a plate spring 23 between the moment support 27 and the ball screw 28 intended. Usually, the actuator is against the ingress of dirt by an elastic bellows 29 protected.
• The 2 shows a third and fourth possible embodiment of the brake system according to the invention. Between the piston 24 and spindle 13 There is a rigid coupling by the plunger 21 is formed on both sides as a ball joint. On the right side of the spindle here is a corresponding insert 30 screwed.
• On the side of the brake control device 16 . 16a . 14 is the spring 20 in a corresponding embodiment of the pedal transmission device 14 stored, whose guide bar 14a the pedal travel sensor 22 actuated. The feather 20 acts on a fret 31a a storage part 31 with internal return spring 17 , This bearing part is additionally guided in a bore.
• The transmission device 14 is additionally designed as a piston in the housing 15 stored and sealed. The piston chamber is via a solenoid valve 33 and 33a connected to the reservoir. The valve is used for pedal travel blocking by means of the transmission device 14 , If an HZ piston return is used to reduce the pressure, this acts on the spring 20 and not on the pedal 16 , because with locked solenoid valve 33 . 33a only one movement can take place within the fluid compression. The return of the piston chamber is for this purpose via the solenoid valve 33 closed. When the piston stroke, z. B. in a jump in the coefficient of friction, is greater than the spring travel, the solenoid valves are via appropriate evaluation of the differential path between piston travel and pedal travel 33 . 33a open. In the lower half of the picture, pedal forward movement is blocked for the same purpose, making it impossible to increase the pedal travel.
• The 3 shows a fourth possible embodiment of the brake system according to the invention. The 3a shows a cross-sectional view corresponding to the section xx acc. 3 , In this embodiment, an electromechanical pedal lock is realized. The transmission device 14 is over jetties 14a in the case 15a (S. 3a ) stored. In the case 15a is a magnetic yoke floating vertically 34 with conclusion 36 stored. The magnetic flux passing through coil 35 is generated, flooded yoke 34 , Inference 36 and footbridges 14a and generates a frictional force for pedal lock in both directions. To reinforce the frictional force can be used in a known technique magnetically conductive fins. Variable current allows the pedal blocking force to be varied. It is also possible to produce a small pedal reaction by only after a certain piston travel, the electromagnetic pedal lock is turned on. This blocking is switched off again when the piston has been returned to the initial position before the pressure reduction. In the upper half of the picture is shown as by several springs ( 20 . 20b ) and a spring washer 20a a progressive spring characteristic can be designed.
• The 4 shows a further embodiment of the brake system gem. of the 2 and 3 without the pedal blocking with the aim to be able to generate a pressure even when the drive is locked. This is made possible by the transmission device 14 the pedal force on the pestle 21 transmits and with acting brake booster additionally the spindle forces on the driver element 41 on the HZ pistons 24 acts. In case of failure of the brake booster, however, only the pedal force acts.
• If now takes place for the pressure reduction for ABS a piston return, so the solenoid 39 active and moves the coupling element 40 in front of the ram collar 21a , Thus, the spindle force on the plunger 21 transmitted and acts against the transmission device 14 and thus enables a pressure reduction in the corresponding brake circuit. In this embodiment, the solenoid is 39 with the spindle 13 movably mounted and requires a flexible connection 39a ,
• It makes sense if the clutch is only effective if the engine function was previously intact to build up pressure. This prevents that when the drive is blocked during pressure build-up in extreme cases, an ABS signal is generated and then despite blocked drive, the clutch is turned on, which would then lead to a blocking of the actuator.
• The spindle 13 and the transmission device 14 have due to tolerances a radial offset and spindle stroke. Thus, when the force of the transmission device 14 on the pestle 21 no load on the spindle 13 should occur with the transmission device 14 connected plungers 31b be designed either biegeastisch, as shown in the upper half or articulated 31c , in particular by means of ball joint, with the transmission device 14 be connected (lower half).
• The 4a shows an alternative embodiment, in which the solenoid with coil 44 on the housing 15 is attached. The anchor 45 is with the coupling element 40 in a plain bearing 47 stored and is via a return spring 46 held in the starting position. The anchor 45 with bearing pin 45a is with a guide rail 43 connected, in which the coupling element 40 with collar axially with the piston movement with slides. Will the solenoid 44 activated, so pushes the guide rail 43 the coupling element 40 in front of a sleeve 42 that with the pestle 21 is in contact. This has the advantage that the hemispherical training is less heavily loaded, since the sleeve 42 here the voltage is reduced. The sleeve 42 must have a fixing ring or spring 48 be axially fixed, as this is moved in case of failure BKV according to the pedal stroke in the spindle bore. shell 42 and coupling element 40 can be cone-shaped. Thus, even with extremely rare failure of the drive during ABS control when switching off the magnet 44 the unlocking forces smaller.
• The 5 shows the brake pressure p, sensor voltage U, piston travel s _K and pedal stroke S _P with suspension. According to the counter-force-dependent deflection creates a differential travel .DELTA.h which leads with a small pedal stroke to a pressure p ₁ and at maximum deflection with .DELTA.h _max to a pressure _P2. This function can be designed with appropriate spring linear or degressive.
• Electromotive brake booster according to the aforementioned prior art, have redundant sensors for rotation angle of the motor or piston stroke s _K and pedal stroke s _P , since especially in Wegsimulatorsystemen the sensors are safety-critical, since among other things pedal stroke and piston travel are unequal. In the system according to the invention can be reduced by a plausibility comparison of the cost of the usual redundancy or waived. This is how z. B. in case of failure of the encoder to determine the pedal stroke s _P no difference Δh, whereby no BKV effect is adjusted. However, the pedal acts on the piston as the failure of the BKV. From the piston stroke s _K value, the error is detected by the plausibility comparison. The same applies to s _K. If the Δh calculation fails, a comparison of the pedal stroke s _P with the measured pressure or current helps.
• The voltages of the sensors must be standardized or adjusted to a reference point because of different output voltage. It is proposed that a balance of the voltages in the starting position, taking into account a correction value, which z. B. can be the Leerweg Δs. This is device-specific and can be determined during commissioning of the vehicle in production or in service.
• The 5a shows the pedal force F _p and piston force F _K over the pedal stroke s. At s ₁ is the Pedal force F _p1 and the piston force F _K1 . The BKV gain K results at s ₁ too

  

  At s _max , F _Pmax and F _{Kmax result} . For a linear spring, the gain K can be linear if Δh is proportional to the pressure or piston force.
• The 5b shows a brake circuit failure. Here arises to S _A no brake pressure, as the failed brake circuit has a pedal diarrhea to S _A result. Thereafter, the piston counteracting force acts and, in turn, Δh to the BKV function, as in FIG 5 described. Here can z. B. the gain can be increased because at the same pressure corresponding to the failure of the brakes in the sum of a smaller braking force.
• In hybrid vehicles, a variable gain, in particular a lower gain can also be used to compensate for the additional braking effect of the generator during recuperation.
• There follow further embodiments of the invention:
• Embodiment 1
• Brake system comprising an electric motor brake booster, wherein the master cylinder or tandem master cylinder 5 via a spindle drive 13 from an electric motor 11 . 12 is driven and connected in ABS operation for pressure reduction with this, wherein the one or more work spaces of the brake booster via hydraulic lines 6 . 7 with the wheel cylinders of wheel brakes 9a - 9d in conjunction and are each a wheel brake 9a - 9d a controllable valve 8a . 8b . 8c . 8d is assigned, and that by means of a control device, a pressure build-up and pressure reduction in the wheel brakes 9a - 9d by means of the brake booster and the controlled valves 8a - 8d simultaneously and / or successively, wherein a brake actuator 16 . 16a . 14 in normal braking operation power assisting on the spindle 13 and / or the piston 24 the brake booster acts.
• Embodiment 2:
• Brake system according to Embodiment 1, wherein in ABS operation, the spindle 13 or the piston 24 the brake actuator 16 . 16a . 14 subjected to force and / or misaligned.
• Embodiment 3
• Braking system according to embodiment 1 or 2, wherein the actuating device 16 . 16a . 14 via at least one spring element 20 . 20b , in particular a compression spring, on the spindle 13 and / or the piston 24 the brake booster acts.
• Embodiment 4
• Brake system according to one of embodiments 1 to 3, wherein the spring element 20 with one end to a transmission device 14 or the pedal ram 16a and with its other end on the spindle 13 , the piston 24 or the piston rod 21 supported.
• Embodiment 5:
• Brake system according to embodiment 3 or 4, wherein the at least one spring element 20 has a linear or degressive force-displacement curve for the upper force range.
• Embodiment 6:
• Brake system according to one of the embodiments 3 to 5, wherein the spring travel length for maximum brake pressure is at least 1 mm, preferably at least 4 mm.
• Embodiment 7:
• Brake system according to one of the preceding embodiments, wherein the brake actuating device is a brake pedal 16 having, which with a pedal ram 16a is in communication with the pedal ram 16a with a transmission device 14 is connected and the transmission device 14 on the spindle 13 and / or the piston 24 the brake booster acts.
• Embodiment 8:
• Brake system according to embodiment 7, wherein the at least one spring element 20 in or at the transmission facility 14 is arranged.
• Embodiment 9:
• Brake system according to one of the preceding embodiments, wherein an additional return spring element 17 the transmission device 14 or the pedal ram 16a from the piston 24 or the spindle 13 takes off.
• Embodiment 10:
• Brake system according to one of the preceding embodiments, wherein the piston 24 and the spindle 13 constantly or optionally, in particular by means of a switchable coupling 40 - 46 , connected or optionally connectable or uncoupled with each other.
• Embodiment 11:
• Brake system according to embodiment 10, wherein the piston 24 and the spindle 13 optionally connectable to each other by means of positive or non-positive connection.
• Embodiment 12:
• Brake system according to embodiment 10, wherein the piston 24 and the spindle 13 by means of a power transmission means, in particular in the form of a plunger 21 , which may be formed as a bending bar, connected to each other or are connectable.
• Embodiment 13:
• Brake system according to one of the embodiments 10 to 12, wherein the power transmission means 21 through the hollow spindle 13 through with the brake actuator 16 . 16a . 14 being connected, being at the spindle 13 a driver element 41 is arranged, by means of which the power transmission means 21 to build up pressure with the spindle 13 is adjustable, and that in the direction of pressure reduction either by means of the clutch 40 - 46 a positive connection or adhesion between the power transmission means 21 and the spindle 13 can be produced.
• Embodiment 14:
• Brake system according to embodiment 13, wherein when the clutch is engaged 40 - 46 the positive connection for adjusting the power transmission means 21 for pressure reduction or retraction of the piston 24 by a coupling element 40 , which in particular as a stop for the power transmission ram 21 serves, wherein the coupling element 40 through the cylindrical wall of the spindle 13 extends through.
• Embodiment 15:
• Brake system according to one of embodiments 10 to 14, wherein the clutch 40 - 46 a housing fixed, drive 44 . 46 . 47 comprising the coupling element 40 adjusted, wherein the coupling element 40 relative to the drive 44 is mounted displaceably parallel to the spindle axis.
• Embodiment 16:
• Brake system according to one of the embodiments 10 to 15, wherein the clutch 40 - 46 a drive 44 . 46 . 47 for adjusting the coupling element 40 having, wherein the drive to the spindle 13 is attached.
• Embodiment 17:
• Brake system according to one of the embodiments 10 to 16, wherein the coupling element 40 through the cylindrical wall of the spindle 13 extends through.
• Embodiment 18:
• Brake system according to one of the embodiments 10 to 17, wherein the coupling element 40 from a spring element 46 in the direction of the disengaged position is subjected to force.
• Embodiment 19:
• Braking system according to one of the embodiments 10 to 18, wherein the control device, the clutch 40 - 46 only then closes, if previously the engine function of the drive 11 . 12 was found to be in order.
• Embodiment 20:
• Brake system according to one of the preceding embodiments, wherein the brake system comprises a locking device by means of which the movement of the brake operating device is blocked.
• Embodiment 21:
• Brake system according to embodiment 20 wherein the locking device can block the brake operating device in any position or in a certain range of motion.
• Embodiment 22:
• Brake system according to embodiment 20 or 21, wherein the locking device is driven hydraulically or electrically, in particular by means of an electric motor or electromagnet, and to the actuating device, in particular the transmission device 14 acts.
• Embodiment 23:
• Brake system according to one of the embodiment 18 to 20, wherein a control device, the locking device in dependence of Signals from the ABS / ESP controller and the piston and actuator positions.
• Embodiment 24:
• Brake system according to one of the preceding embodiments, wherein the brake system comprises sensors for determining the piston position and the position of the brake actuator, and the control device of the brake system drives the drive of the brake booster as a function of the two positions to each other, the drive of the brake booster.
• Embodiment 25:
• Brake system according to embodiment 24, wherein the control device from the determined positions of the piston 13 and brake actuator 16 . 16a . 14 determines the pedal force and based on the proportional to the pedal force difference Δh the drive 11 . 12 the brake booster drives.
• Embodiment 26:
• Brake system according to one of the preceding embodiments, wherein the brake system is a pressure sensor 10 has, with which the pressure in pressure piston circuit can be determined, wherein the pressure control for the wheel brakes 9a - 9d based on the pressure volume characteristics.
• Embodiment 27:
• Brake system according to one of the embodiments 1 to 25, wherein by means of the current consumption of the electric drive of the brake booster, in particular by means of a shunt 26 the pressure proportional to the current is measured and the pressure control for the wheel brakes 9a . 9b . 9c . 9d on the basis of the pressure volume characteristics and the current, in particular without the use of a pressure sensor occurs.
• Embodiment 28:
• A braking system according to any one of the preceding embodiments, wherein the control means for the state variables "brake operating device, in particular pedal stroke s _p, and piston position s _K performs a plausibility check.
• Embodiment 29:
• Braking system according to one of the preceding embodiments, wherein the control device performs a normalization and adjustment of the sensor signals, in particular for the pressure, position and / or rotary encoder, wherein the adjustment in the initial position of the brake pedal 16 , Spindle 13 and pistons 24 taking into account the previously determined real distance Δs as the correction value.
• Embodiment 30:
• Brake system according to one of the preceding embodiments, wherein the control device, the spring travel of the spring 20 used as a control variable for the adjustment of the brake booster.
• Embodiment 31:
• Brake system according to one of the preceding embodiments, wherein the return springs of the HZ or THZ the piston 24 as well as the spindle 13 in their initial position adjust.
• Embodiment 32:
• Brake system according to one of the preceding embodiments, wherein a spring 3 the spindle 13 in the direction of their initial position and the HZ or THZ springs the piston 24 force or adjust in its initial position.
• Embodiment 33:
• Braking system according to one of the preceding embodiments, wherein the at the transmission device 14 or the piston system 24 . 21 . 30 a storage part 31 is mounted displaceably parallel to the spindle axis, wherein the bearing part 31 a flexible elastic plunger 31b for power transmission, to the piston system or the transmission device 14 having.
• Embodiment 34:
• Brake system according to embodiment 33, wherein the plunger 31c by means of ball joint on the bearing part 31 is articulated.
• Embodiment 35:
• Brake system according to one of the preceding embodiments, wherein the control means adjusts the brake booster in dependence on the braking effect achieved by means of recuperation.
• LIST OF REFERENCE NUMBERS

1

EC motor

2

spindle

3

Spindle provision

4

Rotary encoder (position transmitter)

5

HZ or THZ

6

Pressure line from the push rod piston

7

Pressure line from the floating piston

8a-8d

2/2 solenoid valves as switching valves

9a-9d

wheel cylinder

10

thruster

11

stator

12

rotor

13

spindle

14

transmission equipment

14a

guide web

15

casing

15a

Housing bearing for transmission device

16

brake pedal

16a

pedal tappet

17

Return spring

18

disc

19

circlip

20

compression spring

20a

spring washer

20b

second compression spring

21

tappet

21a

ram Bund

22

pedal stroke

23

Belleville spring

24

Push rod piston

25

motor Controller

26

shunt

27

torque support

28

Ball screw drive

29

bellows

30

insert

31

bearing part

31a

Bunch of storage part

31b

flexible elastic plunger

31c

articulated pestle

32

drilling

33/33

2/2 solenoid valve

34

yoke

35

Kitchen sink

36

conclusion

37

magnetic flux

38

slats

39

solenoid

39a

flexible electrical connection

40

coupling member

41

dogging

42

shell

43

guide rail

44

Solenoid with coil

45

armature

45a

bearing bolt

46

Return spring

47

storage

48

feather

Claims (13)

1. Method for controlling an electromotive brake booster, in which the master cylinder or tandem master cylinder ( 5 ) of an electric motor ( 11 . 12 ) is driven, wherein a brake actuator ( 16 . 16a . 14 ) in normal braking operation power assisting on a spindle ( 13 ) and / or a piston ( 24 ) of the brake booster, comprising the steps of: a. Detecting a Piston Travel (sK) of the Master Cylinder or Tandem Master Cylinder ( 5 ), wherein the piston travel (sK) via a rotary encoder ( 4 ) of the electric motor ( 11 . 12 ) is detected; b. Detecting a stroke of the brake actuator ( 16 . 16a . 14 ); c. Determining a path difference (Δh) between piston ( 24 ) and brake actuator ( 16 . 16a . 14 ), based on the detected piston stroke (sK) and the detected stroke of the brake actuator ( 16 . 16a . 14 ); d. Using the path difference (Δh) to control the electromotive brake boost.
2. Method according to claim 1, characterized in that the stroke of the brake actuating device ( 16 . 16a . 14 ) due to a spring ( 20 ) is greater than the piston travel (sK).
3. Method according to one of the preceding claims, characterized by a standardization of sensor tolerances by a small idle displacement Δs between the brake control device ( 16 . 16a . 14 ) and spindle ( 13 ) and when changing the voltage of a pedal stroke sensor ( 22 ) this position serves as a basis.
4. Method according to one of the preceding claims, characterized in that upon receipt of a control command to build up a certain pressure, the brake pressure control is based on a stored pressure volume characteristic.
5. A method according to claim 4, characterized in that the previously recorded via piston stroke (sK) and pressure measurement and stored in a map pressure volume curve the corresponding piston movement via the rotary encoder with appropriate pressure in the brake circuits takes place when the piston ( 24 ) of the master cylinder receives a command to build a certain pressure, the pressure sensor measures the pressure of the master cylinder and between master cylinder ( 5 ) and wheel control valves ( 8a - 8d ) is arranged.
6. Method according to one of the preceding claims, characterized in that corresponding to the counter-force-dependent deflection Difference path Δh between stroke of the brake control device ( 16 . 16a . 14 ) and piston travel (sK) is formed, the small stroke of the brake actuator ( 16 . 16a . 14 ) to a first brake pressure (p1) and at maximum deflection (Δh _max ) of the brake control device ( 16 . 16a . 14 ) leads to a second brake pressure (p2), wherein the function of the path difference (Δh) with a corresponding spring ( 20 ) is linear or degressive.
7. Method according to claim 6, characterized by: a plausibility comparison by evaluation of the stroke of the brake actuating device ( 16 . 16a . 14 ) with respect to the piston travel (sK) and / or by evaluating a pressure in the master cylinder or the electric motor ( 11 . 12 ) relative to the stroke of the brake actuator ( 16 . 16a . 14 ).
8. Method according to one of the preceding claims, characterized by: normalization of the voltages of the sensors ( 22 . 4 ) for detecting the stroke of the brake actuator ( 16 . 16a . 14 ) and for detecting the piston travel (sK) on a reference point by taking into account a free travel (Δs) of the brake actuator ( 16 . 16a . 14 ).
9. Method according to Claim 1, in which a) a linear spring ( 20 ) is used; b) a pressure or a piston force proportional to the path difference (Δh) is set to obtain a linearly dependent on the path difference (Δh) brake boost K = Fk / Fp, where Fk is the piston force and Fp is the pedal force.
10. Method according to one of claims 1 to 8, characterized in that the differential path (Δh) is determined by a progressive spring characteristic, wherein the progressive spring characteristic by a plurality of springs ( 20 . 20b ) is designed.
11. Braking system with - an electromotive brake booster, in which the master cylinder or tandem master cylinder ( 5 ) of an electric motor ( 11 . 12 ) is driven, - a control which is designed to a) a piston stroke (sK) of the master cylinder or tandem master cylinder ( 5 ), wherein the piston travel (sK) via the rotary encoder of an electric motor ( 11 . 12 ) is detected; b) a stroke of a brake actuator ( 16 . 16a . 14 ), wherein the brake actuator ( 16 . 16a . 14 ) in normal braking operation power assisting on a spindle ( 13 ) and / or a piston ( 24 ) of the brake booster acts, the stroke due to a spring ( 20 ) is greater than the piston travel (sK); c) a path difference (Δh) between piston ( 24 ) and brake actuator ( 16 . 16a . 14 ) based on the detected piston stroke (sK) and the detected stroke of the brake actuator ( 16 . 16a . 14 ) to determine; d) to use the path difference (Δh) to control the electromotive brake booster.
12. Hybrid vehicle with a brake system according to claim 11, wherein the brake system is adapted to use a variable gain to compensate for an additional braking effect of a generator of the hybrid vehicle when recuperating.
13. Hybrid vehicle according to claim 11, wherein the brake system is adapted to use a lower gain to compensate for an additional braking effect of a generator of the hybrid vehicle during recuperation.

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