DE112009004636B4

Abstract

The invention relates to a brake system having an electromotive brake booster, in which the master cylinder or tandem master cylinder (5) via a spindle drive (13) by an electric motor (11, 12) is driven and is 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) are in communication and a respective wheel brake (9a-9d) is associated with a controllable valve (8a, 8b, 8c, 8d) , 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 force-supporting acts on the spindle (13) and / or the piston (24) of the brake booster.

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Description

[0001] The present invention relates to a braking system having the features of the generic concept of claim 1.

Prior art

[0002] The effectiveness of the active safety functions of ABS and in particular ESP is such that it will soon be required by law in the USA and the EU. Great efforts are being made to reduce the effort. According to the state of the art, several solutions are known to reduce effort.

[0003] A first solution is the integration of pressure control and brake boosting, as known from DE 10 2005 018 649 A1. This system is based on a displacement simulator with additional functions and actuators for the case of failure of the drive. This requires a corresponding effort.

[0004] A second solution is to reduce the valve effort by a multiplex operation. DE 34 40 972 A1 describes a hydraulic brake booster BKV in which pressure control is performed by means of the THZ with corresponding valves in multiplex operation. This system does not meet the high dynamic requirements, so that the switching times are too high.

[0005] In addition, the noise when switching the valves is too high. The same applies with regard to the dynamics for a pneumatic system such as is previously known from DE 38 43 159 A1 or DE 39 08 062 A1.

[0006] DE 10 2005 018 649 A1 describes an electromotive multiplex system with high dynamics as a so-called twin and tandem solution with travel simulator. To prevent pedal reaction during ABS operation, an idle stroke is provided between the pedal and the drive unit. The disadvantage here is that additional pedal travel is required in the event of drive failure.

[0007] Furthermore, an electromotive brake booster is known from FR 2 860 474 A1, in which an electric motor adjusts a brake force assistance force via a spindle. The brake pedal acts on the piston of the brake booster via a pedal plunger. The force applied to the piston by the brake pedal is used by the spindle drive to control the power assist with the electric motor. However, force measurement to determine the required brake force assistance has proven to be impractical.

[0008] Various brake boosters are known from 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 43 27 206 A1.

[0009] DE 10 2004 050 103 A1 describes a brake booster in which a pedal acts mechanically on the pistons of a tandem master brake cylinder via a linkage and a spring element. A control of an arranged electromotive drive is based on a force transmitter and a pressure sensor.

[0010] The configuration of DE 10 2004 050 103 A1 is complex. Furthermore, the achieved braking characteristic is not optimal.

[0011] The task of the present invention is to further develop a brake system with an electromotive brake booster in such a way that it does not require a travel simulator and that it is possible to build up braking force in the wheel brakes even in the event of a malfunction, i.e. in the event of failure of the electromotive drive of the master brake cylinder piston (= HZ piston).

[0012] This task is advantageously solved with a brake system having the features of claim 1. Advantageous embodiments of the brake system according to claim 1 result from the features of the subclaims.

[0013] Even if the travel simulator is omitted, the driver must receive a counterpressure when the brake pedal is actuated. According to the invention, this is achieved by the brake pedal acting directly on the piston system of the brake booster via the pedal plunger and possibly via additional transmission elements. A force is thus exerted on the piston system via the brake pedal, which force is amplified by the brake booster during normal braking operation, or the driver is assisted by the brake booster.

[0014] When a spring, in particular a strong spring, is used between the actuator and the brake actuator, the stroke of the brake actuator or the pedal stroke is greater than the piston stroke, which is detected via the motor with rotary encoder. This travel difference can be used for brake force control or amplification, resulting in considerably simpler control. Advantageously, the sensor tolerances, e.g. different offset voltages, are normalized by incorporating a small idle stroke between the actuator and the drive and, for example, when the voltage of the pedal stroke encoder changes, this position serves as the basis. Another possibility is that during commissioning or servicing of the system, the brake pedal is actuated until it moves the spindle and da- DE 11 2009 004 636 B4 2017.08.03 3/15 with the rotor. The movement is thereby measured by means of the angle of rotation sensor. At this position, the sensor voltage is then calibrated.

[0015] For pressure control, a pressure transducer is provided in the pressure rod circuit which, together with the piston travel, is used to determine the pressure volume characteristic curve. This characteristic curve is the basis for accurate pressure control. For further system simplification, especially for ABS, the motor current can also be measured via a shunt, which is proportional to the motor torque and thus pressure. This measurement or pressure can also serve for plausibility monitoring of the sensor signals, so that redundant sensors can be dispensed with.

[0016] In the following, various possible embodiments of the braking system according to the invention are explained in more detail by way of example with reference to drawings.

[0017] They show:

[0018] Fig. 1: two possible embodiments of a braking system according to the invention;

[0019] Fig. 2: Third possible embodiment of a braking system according to the invention;

[0020] Fig. 3: fourth possible embodiment of a braking system according to the invention;

[0021] Fig. 3a: cross-sectional view through section x-x in Fig. 3;

[0022] Fig. 4: fifth possible embodiment of a brake system according to the invention with coupling for decoupling the HZ piston and the brake actuating device for non-reinforced brake pressure build-up in the event of a malfunction; [0023] Fig. 4a: detailed representation of the coupling according to Fig. 4;

[0024] Fig. 5: Brake pressure P, sensor voltage U, piston travel sK and pedal stroke SP with suspension;

[0025] Fig. 5a: Pedal force and piston force over pedal stroke s;

[0026] Fig. 5b: Brake pressure P, sensor voltage U, piston travel sK and pedal stroke SP with suspension during a brake circuit failure;

[0027] Fig. 1 shows the basic structure of the braking system according to the invention, consisting of HZ or THZ 5, EC motor with stator 11 and rotor 12, spindle 13 for driving the push rod piston 24 via the plunger 21, and a rotary encoder 4 for determining the position of the push rod piston 24 and detecting the rotor position or piston travel.

[0028] If the piston 24 receives the actuating command to build up a certain pressure, the corresponding piston movement is effected via the rotary angle encoder 4 with corresponding pressure in the brake circuits via the pressure volume characteristic curve previously recorded via piston travel and pressure measurement and stored in a characteristic diagram. In simplified systems, e.g. ABS, a shunt 26, which is necessary for motor control anyway, can also be used for current measurement of control 25. With subsequent short constant pressure, which is usually the case with braking, the correlation comparison is made on the basis of new measurement data with the stored map data. If there is a deviation, the pressure-volume characteristic curve for each wheel brake is recorded again individually when the vehicle comes to a standstill later and the map is corrected. If the deviation is significant, e.g. at a wheel cylinder, the user is advised to visit the workshop.

[0029] The pressure generated in the HZ or THZ reaches the wheel cylinders 9a to 9d via lines 6 and 7 from the pressure rod piston and floating piston via the 2/2 solenoid valves 8a to 8d. Here, the dimensioning of the flow resistances for the multiplex process in the lines and valves is of great importance. In addition, the coordination of the switching and changeover times is crucial. This is described in detail in further applications of the applicant and is not the subject of the present invention in detail.

[0030] When the brake pedal 16 is actuated, it acts via the pedal plunger 16a on the actuating device 14 and the latter acts on the spindle 13. In the lower half of the figure, an idle stroke Δs is drawn. When the brake pedal 16 is not actuated, the spring 17 lifts the transmission device 14 off the spindle 13 by the idle stroke Δs. The idle stroke Δs must be overcome with each braking operation until the collar of the transmission device 14 meets the spindle 13. In this solution, the drive (spindle) acts directly on the brake pedal 16 via the transmission device 14, which can be disruptive during pressure reduction in ABS and corresponding rapid piston movement due to the impact. In this case, the braking force is boosted by a force sensor not shown as described in DE 10 2004 050 103 A1. The return spring 17 between the spindle 13 and the transmission device 14 presses the latter against a stop in the housing 15.

[0031] A considerable reduction of the impact is achieved by a solution as shown in the upper half of the figure DE 11 2009 004 636 B4 2017.08.03 4/15. Here, a strong compression spring 20 acts on the spindle 13 via a washer 18. For assembly reasons, this washer 18 is fixed via a circlip 19. The spring 20 is designed linearly or degressively for a pedal force or rod force with BKV function for a maximum pressure of e.g. 200 bar and has a spring stroke of 4-6 mm. The spring 20 is designed proportional to the rod force and transmits this force to the spindle 13, which is also acted upon by the adjustment force of the motor 11, 12 according to the selected BKV gain. Both forces together result in the force acting on the piston. If a rapid piston return occurs when the pressure is reduced for ABS control, this acts on the pedal in a damped manner via spring 20. A 10 bar pressure reduction in the control cycle corresponds to approximately 0.5 mm ≈ 10% of the spring travel in a mid-size vehicle.

[0032] Thus, the pedal stroke corresponding to this stroke is greater than the piston travel. The spring 20 may also be slightly preloaded for appropriate pedal characteristics. This can use different strokes for brake force amplification in that the pressure is proportional to the differential travel. This travel is obtained from the signals from pedal stroke sensor 22 and piston travel. The piston travel can be determined via the rotation angle sensor 4. The brake pressure is controlled via the piston travel on the basis of the pressure volume characteristic. The brake actuator 16, 16a, 14 is permanently in contact with the drive via the spring 20 during braking. According to the desired amplification, the motor transmits the corresponding force to the piston 24 via the spindle 13, so that pedal force and amplifier force result in the piston force proportional to the pressure. The spindle force is transmitted to the push rod piston 24 via a movably mounted plunger 21. Here, the plunger 21 is coupled to both the push rod piston 24 and the spindle 13 so that high pressure gradients can be realized even at low pressures. The plunger has the task of not transmitting the possible misalignment of the spindle 13 and impact of the ball screw to the push rod piston 24. The spindle torque support 27 runs in a groove of the housing, preferably with good sliding properties, corresponding to the piston travel. The torque support is thereby also used as a stop, since the THZ return springs act on the spindle 13 and, in addition to the piston return, also have the task of motor return.

[0033] The piston or drive reset is performed by the motor. In order to reduce additional load on the ball screw in the event of a faulty reset and a hard stop, a disc spring 23 is provided between the torque support 27 and the ball screw 28. Typically, the actuator is protected against ingress of dirt by an elastic bellows 29.

[0034] Fig. 2 shows a third and fourth possible embodiment of the braking system according to the invention. There is a rigid coupling between the piston 24 and spindle 13, in that the plunger 21 is designed as a ball joint on both sides. On the right-hand side of the spindle, a corresponding insert piece 30 is screwed in here.

[0035] On the side of the brake actuating device 16, 16a, 14, the spring 20 is embedded in a corresponding formation of the pedal transmitting device 14, the guide web 14a of which actuates the pedal travel sensor 22. The spring 20 acts on a collar 31a of a bearing part 31 with an internal return spring 17. This bearing part is additionally guided in a bore.

[0036] The transmission device 14 is additionally formed as a piston, which is mounted and sealed in the housing 15. The piston chamber is connected to the reservoir via a solenoid valve 33 and 33a. The valve is used to block pedal travel by means of the transfer device 14. If an HZ piston return occurs to relieve pressure, it acts on the spring 20 and not on the pedal 16, since with the solenoid valve 33, 33a blocked, movement can only occur within the fluid compression. The return from the piston chamber is closed for this purpose via solenoid valve 33. If the piston travel is greater than the spring travel, e.g. in the event of a jump in the coefficient of friction, the solenoid valves 33, 33a are opened via corresponding evaluation of the difference between the piston travel and the pedal travel. In the lower half of the figure, the pedal forward movement is blocked for the same purpose, in that the pedal travel can no longer be increased.

[0037] Fig. 3 shows a fourth possible embodiment of the braking system according to the invention. Fig. 3a shows a cross-sectional view corresponding to the section x-x according to Fig. 3. In this embodiment, an electromechanical pedal lock is implemented. The transmission device 14 is mounted in the housing 15a (see Fig. 3a) via webs 14a. A magnet yoke 34 with a return 36 is mounted in the housing 15a in a vertically floating manner. The magnetic flux generated by coil 35 flows through yoke 34, return 36 and webs 14a and generates a frictional force for pedal locking in both directions. Magnetically conductive laminations can be used in known technology to enhance the frictional force. Variable current can be used to vary the pedal locking force. It is also possible to generate a small pedal reaction by switching on the DE 11 2009 004 636 B4 2017.08.03 5/15 electromagnetic pedal blocking only after a certain piston travel. This blocking is switched off again when the piston has been returned to its initial position before the pressure reduction. In the upper half of the figure, it is shown how a progressive spring characteristic can be designed by several springs (20, 20b) as well as a spring washer 20a.

[0038] Fig. 4 shows a further embodiment of the brake system according to Fig. 2 and Fig. 3 without the pedal blocking with the aim of being able to generate a pressure even when the drive is blocked. This is made possible by the transmission device 14 transmitting the pedal force to the plunger 21 and, when the brake booster is acting, additionally applying the spindle forces to the HZ piston 24 via the driver element 41. In contrast, when the brake boosting fails, only the pedal force is effective.

[0039] If a piston reset now occurs for the pressure reduction for ABS, the solenoid 39 becomes active and moves the clutch element 40 in front of the tappet collar 21a. Thus, the spindle force is transmitted to the plunger 21 and acts against the transmission device 14, allowing pressure reduction in the corresponding brake circuit. In this embodiment, the solenoid 39 is movably mounted with the spindle 13 and requires a flexible connection 39a.

[0040] It is useful if the clutch is only effective when the motor function is intact beforehand to build up pressure. This prevents an ABS signal from being generated in extreme cases when the drive is blocked during pressure build-up, and then the clutch being engaged despite the drive being blocked, which would then lead to the actuator being blocked.

[0041] The spindle 13 and the transmission device 14 have radial offset and spindle runout as a result of tolerances. To ensure that no stress occurs on the spindle 13 when the force of the transmission device 14 is applied to the plunger 21, the plunger 31b connected to the transmission device 14 should either be of a flexurally elastic design, as shown in the upper half of the figure, or be connected to the transmission device 14 in an articulated manner 31c, in particular by means of a ball joint (lower half of the figure).

[0042] Fig. 4a shows an alternative embodiment in which the solenoid with coil 44 is attached to the housing 15. The armature 45 is mounted with the coupling element 40 in a plain bearing 47 and is held in the initial position by a return spring 46. The armature 45 with bearing pin 45a is connected to a guide rail 43, in which the coupling element 40 with collar slides axially with the piston movement. When the solenoid 44 is activated, the guide rail 43 presses the coupling element 40 in front of a sleeve 42, which is in contact with the plunger 21. This has the advantage that the hemispherical formation is less stressed, since the sleeve 42 reduces the stress here. The sleeve 42 must be axially fixed via a fixing ring or spring 48, since this is moved in the spindle bore in accordance with the pedal stroke during failure BKV. Sleeve 42 and coupling element 40 can be tapered. Thus, even if the actuator fails extremely infrequently during ABS control when the solenoid 44 is switched off, the unlocking forces are smaller.

[0043] Fig. 5 shows the brake pressure p, sensor voltage U, piston travel sK and pedal stroke SP with suspension. According to the counterforce-dependent deflection, a differential travel Δh arises, which leads to a pressure p1 with a small pedal stroke and to a pressure p2 with maximum deflection with Δhmax. This function can be made linear or degressive with an appropriate spring.

[0044] Electric motor brake boosters according to the aforementioned prior art have redundant sensors for the motor's angle of rotation or piston travel sK and pedal stroke sP , since the sensors are critical to safety, particularly in travel simulator systems, since, among other things, the pedal stroke and piston travel are not equal. In the system according to the invention, the effort for the otherwise usual redundancy can be reduced or dispensed with by means of a plausibility comparison. For example, if the encoder for determining the pedal stroke sP fails, there is no differential travel Δh, which means that no BKV action is applied. However, the pedal acts on the piston as in the case of BKV failure. From the piston travel sK - value, the error is detected by the plausibility comparison. The same is true for sK . If the Δh-calculation fails, a comparison of the pedal stroke sP with the measured pressure or current helps.

[0045] The voltages of the sensors have to be normalized or adjusted to a reference point because of different output voltages. It is suggested to perform an adjustment of the voltages in the initial position taking into account a correction value, which can be e.g. the open travel Δs. This is device-specific and can be determined during commissioning of the vehicle in production or service. [0046] Fig. 5a shows the pedal force Fp and piston force FK over the pedal stroke s. At s1, the pedal force is Fp1 and the piston force is FK1. The BKV gain K is obtained at s1 to DE 11 2009 004 636 B4 2017.08.03 6/15 At smax is FPmax and FKmax. For linear spring, the gain K can be linear if Δh is proportional to the, pressure and piston force, respectively.

[0047] Fig. 5b shows a brake circuit failure. Here, there is no brake pressure until SA, because the failed brake circuit results in a pedal failure until SA. After that, the piston counterforce acts and again a Δh to the BKV function occurs, as described in Fig. 5. Here, for example, the gain can be increased, since the same pressure corresponding to the brake failure results in a smaller braking force in total.

[0048] 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.

[0049] Further embodiments of the invention follow:

Embodiment Example 1:

[0050] Brake system, comprising an electromotive brake booster, in which the master brake cylinder or tandem master brake cylinder 5 is driven by an electric motor 11, 12 via a spindle drive 13 and is connected thereto in ABS operation for pressure reduction, wherein the working chamber or chambers of the brake booster are connected to the wheel cylinders of wheel brakes 9a-9d via hydraulic lines 6, 7, and each wheel brake 9a-9d has a controllable valve 8a, 8b, 8c, 8d is assigned to each wheel brake 9a-9d, and in that 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 takes place simultaneously and/or successively by means of a control device, a brake actuating device 16, 16a, 14 acting in a force-assisting manner on the spindle 13 and/or the piston 24 of the brake booster during normal braking operation.

Example of embodiment 2:

[0051] Brake system according to embodiment example 1, wherein in ABS operation, the spindle 13 or the piston 24 force-assists and/or displaces the brake actuating device 16, 16a, 14.

Embodiment example 3:

[0052] Brake system according to embodiment example 1 or 2, wherein the actuating device 16, 16a, 14 acts on the spindle 13 and/or the piston 24 of the brake booster via at least one spring element 20, 20b, in particular a compression spring.

Example of embodiment 4:

[0053] Brake system according to any of embodiments 1 to 3, wherein the spring element 20 bears with its one end against a transmission device 14 or the pedal plunger 16a and with its other end against the spindle 13, the piston 24 or the piston rod 21.

Embodiment 5:

[0054] Brake system according to embodiment example 3 or 4, wherein the at least one spring element 20 has a linear or degressive force-displacement characteristic for the upper force range.

Embodiment example 6:

[0055] Brake system according to any one of embodiments 3 to 5, wherein the spring travel length for maximum brake pressure is at least 1 mm, preferably at least 4 mm.

Embodiment example 7:

[0056] Brake system according to any one of the preceding embodiments, wherein the brake actuating device comprises a brake pedal 16 which is in communication with a pedal plunger 16a, wherein the pedal plunger 16a is connected to a transmission device 14 and the transmission device 14 acts on the spindle 13 and/or the piston 24 of the brake booster.

Embodiment example 8:

[0057] Braking system according to embodiment example 7, wherein the at least one spring element 20 is arranged in or on the transmission device 14.

Embodiment example 9:

[0058] Brake system according to any of the preceding embodiments, wherein an additional return spring element 17 lifts the transmission device 14 or the pedal plunger 16a from the piston 24 or the spindle 13.

Embodiment 10:

[0059] Brake system according to one of the preceding embodiments, wherein the piston 24 and the spindle 13 are permanently or optionally connected or optionally connectable or disconnectable to each other, in particular by means of a switchable coupling 40-46. EN 11 2009 004 636 B4 2017.08.03 7/15

Embodiment 11:

[0060] Brake system according to embodiment example 10, wherein the piston 24 and the spindle 13 are selectively connectable to each other by means of positive or non-positive engagement.

Embodiment example 12:

[0061] Brake system according to embodiment example 10, wherein the piston 24 and the spindle 13 are or can be connected to one another by means of a force transmission means, in particular in the form of a plunger 21, which can be designed as a bending rod.

Example of embodiment 13:

[0062] Brake system according to one of embodiments 10 to 12, wherein the force transmission means 21 is connected to the brake actuating device 16, 16a, 14 through the hollow spindle 13, wherein a driver element 41 is arranged on the spindle 13, by means of which driver element the force transmission means 21 can be adjusted to build up pressure with the spindle 13, and in that, in the direction of pressure reduction, a form-fit or force-fit can optionally be produced between the force transmission means 21 and the spindle 13 by means of the coupling 40-46.

Example of embodiment 14:

[0063] Brake system according to embodiment example 13, wherein, when the coupling 40-46 is engaged, the form closure for adjusting the force transmission means 21 for pressure reduction or for retracting the piston 24 is effected by a coupling element 40, which serves in particular as a stop for the force transmission ram 21, the coupling element 40 extending through the cylindrical wall of the spindle 13.

Embodiment 15:

[0064] Brake system according to any one of embodiments 10 to 14, wherein the coupling 40-46 has a drive 44, 46, 47, which is mounted fixed to the housing and adjusts the coupling element 40, wherein the coupling element 40 is mounted so as to be displaceable relative to the drive 44 parallel to the spindle axis.

Embodiment 16:

[0065] Brake system according to any one of embodiments 10 to 15, wherein the coupling 40-46 comprises a drive 44, 46, 47 for adjusting the coupling element 40, wherein the drive is attached to the spindle 13.

Embodiment 17:

[0066] Braking system according to any one of embodiments 10 to 16, wherein the coupling element 40 extends through the cylindrical wall of the spindle 13.

Embodiment example 18:

[0067] Braking system according to any one of embodiments 10 to 17, wherein the coupling element 40 is force-loaded by a spring element 46 in the direction of the disengaged position.

Embodiment example 19:

[0068] Braking system according to any one of embodiments 10 to 18, wherein the control device closes the clutch 40-46 only if the motor function of the drive 11, 12 has previously been found to be OK.

Embodiment example 20:

[0069] A brake system according to any one of the preceding embodiments, wherein the brake system comprises a locking device by means of which the movement of the brake actuating device can be locked.

Embodiment example 21:

[0070] Brake system according to embodiment example 20 wherein the locking device can lock the brake actuating device in any positions or in a certain range of motion.

Embodiment example 22:

[0071] Brake system according to embodiment example 20 or 21, wherein the locking device is driven hydraulically or electrically, in particular by means of an electric motor or electromagnet, and acts on the actuating device, in particular the transmission device 14.

Embodiment example 23:

[0072] Brake system according to any one of embodiments 18 to 20, wherein a control device actuates the locking device as a function of the signals from the ABS/ESP controller and the piston and actuating device positions.

Embodiment example 24:

[0073] Brake system according to any of the preceding embodiments, wherein the brake system has sensors for determining the piston position and DE 11 2009 004 636 B4 2017.08.03 8/15 the position of the brake actuator, and the control device of the brake system controls the drive of the brake booster in dependence on the two positions relative to each other.

Embodiment 25:

[0074] Brake system according to embodiment example 24, wherein the control device determines the pedal force from the determined positions of piston 13 and brake actuating device 16, 16a, 14 and controls the drive 11, 12 of the brake booster on the basis of the differential stroke Δh proportional to the pedal force.

Embodiment 26:

[0075] Brake system according to one of the preceding embodiments, wherein the brake system has a pressure sensor 10 with which the pressure in pressure piston circuit can be determined, wherein the pressure control for the wheel brakes 9a-9d is performed on the basis of the pressure volume characteristics.

Design example 27:

[0076] Brake system according to one of embodiments 1 to 25, wherein the current intensity proportional to the pressure is measured by means of the current consumption of the electric drive of the brake booster, in particular by means of a shunt 26, and the pressure control for the wheel brakes 9a, 9b, 9c, 9d is carried out on the basis of the pressure volume characteristics and the current intensity, in particular without using a pressure sensor.

Embodiment 28:

[0077] Brake system according to one of the preceding embodiments, wherein the control device performs a plausibility check for the state variables "brake actuating device, in particular pedal stroke sp , and piston position sK.

Embodiment 29:

[0078] Brake 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 rotational angle sensors, wherein the adjustment is performed in the initial position of brake pedal 16, spindle 13 and piston 24, taking into account the previously determined real distance Δs as a correction value.

Example of embodiment 30:

[0079] Brake system according to any of the preceding embodiments, wherein the control device uses the spring travel of the spring 20 as a control variable for adjusting the brake force boosting.

Embodiment 31:

[0080] Brake system according to any of the preceding embodiments, wherein the return springs of the HZ- or THZ adjust the piston 24 and the spindle 13 to their initial positions.

Embodiment 32:

[0081] Braking system according to any of the preceding embodiments, wherein a spring 3 forces or displaces the spindle 13 in the direction of its initial position and the HZ or THZ springs force or displace the piston 24 to its initial position.

Example of embodiment 33:

[0082] Brake system according to one of the preceding embodiments, wherein the bearing part 31 mounted on the transmission device 14 or the piston system 24, 21, 30 is displaceable parallel to the spindle axis, wherein the bearing part 31 has a flexurally elastic plunger 31b for transmitting force, to the piston system or the transmission device 14.

Example of embodiment 34:

[0083] Brake system according to embodiment example 33, wherein the plunger 31c is hinged to the bearing part 31 by means of a ball joint.

Embodiment example 35:

[0084] Brake system according to any one of the preceding embodiments, wherein the control device adjusts the brake force boosting in dependence on the braking effect achieved by means of recuperation.

List of reference signs

  • 1 EC motor
  • 2 spindle
  • 3 Spindle recuperation
  • 4 Angle of rotation encoder (position encoder)
  • 5 HZ or THZ
  • 6 Pressure line from pressure rod piston
  • 7 Pressure line from floating piston
  • 8a-8d 2/2 solenoid valves as switching valves EN 11 2009 004 636 B4 2017.08.03 9/15
  • 9a-9d Wheel cylinder
  • 10 Pressure transmitter
  • 11 Stator
  • 12 Rotor
  • 13 Spindle
  • 14 Transmission device
  • 14a Guide bar
  • 15 Housing
  • 15a Housing bearing for transmission device
  • 16 Brake pedal
  • 16a Pedal plunger
  • 17 Return spring
  • 18 Washer
  • 19 Circlip
  • 20 Pressure spring
  • 20a spring washer
  • 20b second compression spring
  • 21 Plunger
  • 21a Plunger collar
  • 22 Pedal stroke sensor
  • 23 disk spring
  • 24 push rod piston
  • 25 Motor control
  • 26 Shunt
  • 27 Moment support
  • 28 Ball screw drive
  • 29 Bellows
  • 30 Insert piece
  • 31 Bearing part
  • 31a collar of bearing part
  • 31b flexible plunger
  • 31c articulated plunger
  • 32 Bore
  • 33/33a 2/2 solenoid valve
  • 34 solenoid yoke
  • 35 coil
  • 36 return path
  • 37 Solenoid flow
  • 38 Lamellae
  • 39 Solenoid
  • 39a flexible electrical connection
  • 40 coupling element
  • 41 Driving element
  • 42 sleeve
  • 43 Guide rail
  • 44 Solenoid with coil
  • 45 Magnet armature
  • 45a Bearing bolt
  • 46 Return spring
  • 47 Bearing
  • 48 Spring

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