Description

0001] The invention relates to methods for controlling an electromotive brake booster with the features of the generic term of claim 1.

State of the art

The effectiveness of the active safety functions of ABS and in particular ESP is so great that it will soon be required by law in the USA and the EU. Great efforts are being made to reduce the effort involved. According to the state of the art, various solutions are known which reduce the effort involved.

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

0004] A second solution is 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 by means of the THZ is carried out in multiplex operation with the corresponding valves. This system does not meet the high dynamic requirements, so that the changeover times are too high. In addition, the noise level when switching the valves is too high. The same applies to the dynamics of a pneumatic system as known from DE 38 43 159 A1 or DE 39 08 062 A1.

0005] DE 10 2005 018 649 A1 describes an electric motor multiplex system with high dynamics as a so-called twin and tandem solution with path simulator. To avoid pedal reaction during ABS operation, an idle stroke is provided between the pedal and the drive unit. The disadvantage here is that an additional pedal travel is required if the drive fails.

[0006] FR 2860474 A1 also includes an electric motor brake booster in which an electric motor controls a brake booster force via a spindle. The brake pedal acts on the brake booster piston via a tappet. Based on the force applied to the piston by the brake pedal, the spindle drive regulates the power assistance with the electric motor. However, measuring the force to determine the required brake booster has proven to be impractical.

[0007] Various brake boosters are from DE 10 2006 050 277 A1, DE 195 00 544 A1,

EN 422 90 42 A1, US 5 758 930 A, EP 0 284 718 A2

and DE 4 327 206 A1.

0008] 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. At least the master cylinder is adjusted via a motor by means of a driver. The motor only allows a force to be applied to the piston.

0009] Based on DE 10 2004 050 103 A1, it is the task of the present invention to specify an improved braking system.

0010] This task is advantageously solved with a braking system according to claim 1.

0011] Further advantageous characteristics result from the subclaims.

0012] With ABS control, the brake booster piston is moved back and forth by an electric motor to adjust the wheel brake pressure. Due to the mechanical connection between the piston or spindle on the one hand and the brake actuation device, especially in the form of the brake pedal, on the other hand, the driver feels the piston movement through the reaction in the form of vibrations and impacts. For the damping of the impacts or vibrations, the invention proposes in a further advantageous design a safety element which is arranged between the actuating device on the one hand and the piston system or the spindle on the other hand. By means of the spring element, forces from the brake actuating device can be transmitted to the spindle.

0013] The spring element has advantageous linear or degressive spring characteristics for the upper force range.

0014] The reaction on the brake actuation device can be reduced to advantage by controlling the electromotive pressure modules accordingly. Here it is advantageous if only smaller pressure amplitudes are adjusted or controlled due to more precise pressure control. By providing soft pressure transitions an unpleasant feeling and the hardness of the reactions can be reduced. By using a strongly linear or degressive spring between the drive and the brake pedal transmission device, the reaction to fast piston movement has a more elastic effect on the brake pedal.

0015] Furthermore, it is possible to block the movement of the brake actuation device either completely or to a limited extent by means of a locking device. The locking device can be designed in such a way that the blocking can be done in any position or in a certain range of movement of the brake actuation device. By blocking the transmission device by electro-hydraulic or electro-mechanical means, this reaction can be eliminated or greatly reduced or controlled in a defined manner in standard control operation with small to medium pressure amplitudes, which is particularly advantageous.

0016] In an electric motor drive with high dynamics, it is important, especially in the lower pressure range, to couple the push rod piston to the drive. This is possible either with a spring or alternatively with a rigid coupling, e.g. by means of a plunger.

0017] In order to exclude the possibility that pressure generation is no longer possible if the electric motor drive fails or the spindle drive is blocked, appropriate fall-back lives must be provided. With the brake system according to the invention, the pedal continues to act directly on the piston if the drive fails.

0018] The brake system according to the invention may have a coupling in an advantageous further development by which the piston can be separated from the spindle, especially for piston return. In this design variant, the brake actuation device does not act on the spindle but on the push rod piston or a piston tappet if the electric motor is not effective. When the clutch is opened, the spindle return springs no longer act on the piston, so that the driver only has to apply small actuating forces for braking. The piston is coupled to the spindle by means of a locking bolt which engages through the cylindrical wall of the spindle. The clutch drive can be mounted either on the housing of the brake booster or on the spindle. If the drive is mounted on the housing, the locking bolt must be mounted so that it can be moved in the axial direction of the spindle towards the drive so that it can move with the spindle. The spindle is advantageously equipped with a power transmission element, especially in the form of a bending ram, which connects the piston with the brake actuation device. A driver arranged on the spindle ensures that the force transmission element is moved together with the spindle by the spindle movement to build up pressure. The force transmission element is designed for cooperation with the driver and has a collar-shaped connection to the spindle.

thickening. This collar-shaped thickening also works together with the locking bolt and forms a form closure between spindle and power transmission means when the clutch is closed. This means that the piston can be moved against the pedal force or spring force to reduce pressure and the piston is coupled to the drive, which enables high pressure reduction gradients in the entire pressure range.

0019] The coupling between piston and spindle can be either form-fit or force-locked.

0020] The electromotive brake booster in accordance with DE 10 2004 050 103 A1 requires a force transducer to control the electromotive brake booster. This sensor is complex because of the drift compensation and the lines that move over the full pedal stroke. When using the described, especially strong, spring between the drive and the brake actuation device, the stroke of the brake actuation device or the pedal stroke is greater than the piston travel, which is measured by the motor with the angle of rotation sensor. This path difference can be used for brake force control or amplification, which results in a much simpler control. The advantage of this is that the sensor tolerances, e.g. different offset voltages, are standardized by installing a small idle stroke between the actuating device and the drive and, e.g. when the voltage of the pedal stroke sensor changes, this position serves as the 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 the rotation angle sensor. With this position, the sensor voltages or corresponding digital values are then adjusted.

0021] For pressure control, a pressure transmitter is provided in the push rod circuit which, together with the piston travel, serves to determine the pressure volume characteristic curve. This characteristic curve is the basis for precise pressure control. For further system simplification, especially for ABS, the motor current can also be recorded via a shunt, which is proportional to the motor torque and thus pressure. This measurement or the pressure can also be used for plausibility monitoring of the sensor signals, so that redundant sensors are not necessary.

0022] In the following, various possible designs of the brake system according to the invention are explained in more detail by means of drawings.

[0023] Show it:

0024] Fig. 1: Two possible designs of a brake system according to the invention;

0025] Fig. 2: Third possible version of a brake system according to the invention;

0026] Fig. 3: Fourth possible version of a brake system according to the invention;

0027] Fig. 3a: Cross-section representation through the section x-x in Fig. 3;

0028] Fig. 4: Fifth possible version of a brake system according to the invention with coupling for decoupling the HZ piston and the brake actuation device for the unamplified brake pressure build-up in case of a malfunction;

0029] Fig. 4a: Detailed view of the coupling acc.

Fig. 4;

0030] Fig. 5: Brake pressure P, sensor tension U, piston travel sK and pedal stroke SP with suspension;

0031] Fig. 5a: Pedal force and piston force over the pedal stroke s;

0032] Fig. 5b: Brake pressure P, sensor voltage U, piston travel sK and pedal stroke SP with suspension in case of brake circuit failure;

0033] Fig. 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 for driving the push rod piston 24 via the tappet 21 and an angle of rotation sensor 4 for determining the position of the push rod piston 24 and recording the rotor position or the piston travel.

0034] If piston 24 receives the command to build up a certain pressure, the corresponding piston movement is performed via the angle of rotation encoder 4 with the 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 map. In simplified systems, e.g. ABS, a shunt 26, which is necessary for motor control anyway, can also be used to measure the current of control 25. At a subsequent short constant pressure, which is usually the case during braking, the correlation comparison is based on new measurement data with the stored map data. If there is a deviation, the pressure volume characteristic curve is recorded again for each wheel brake and the characteristic map is corrected. If the deviation is significant, e.g. on a wheel cylinder, the customer is advised to contact the workshop.

0035] The pressure generated in the HZ or THZ reaches the wheel cylinders 9a to 9d via lines 6 and 7 from the push rod piston and floating piston via the 2/2 solenoid valves 8a to 8d. The dimensioning of the flow resistances for the multiplexing process in the lines and valves is of great importance here. In addition, the coordination of the switching and changeover times is decisive. This is described in detail in further applications of the applicant and is not the subject matter of the invention in detail.

0036] When the brake pedal 16 is actuated, it acts via the pedal tappet 16a on the actuating device 14 and this on the spindle 13. An empty stroke Δs is shown in the lower half of the figure. When the brake pedal 16 is not actuated, the spring 17 lifts the transmission device 14 from the spindle 13 by the idle stroke Δs. The idle   14 meets the spindle 13. In this solution, the drive (spindle) acts directly on the brake pedal 16 via the transmission 14, which can interfere with the pressure reduction in ABS and the corresponding rapid piston movement caused by the impact. The brake force is amplified by a force sensor which is not marked as described in DE 10 2004 050 103 A1. The return spring 17 between spindle 13 and transmission device 14 presses it against a stop in the housing 15.

0037] A considerable reduction of the impact is achieved by a solution as shown in the upper half of the picture. In this case, a strong pressure force 20 acts on the spindle 13 via a washer 18. For assembly reasons, this washer 18 is fixed via a safety ring 19. The spring 20 is designed linear or degressive 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 proportionally to the rod force and transmits this force to the spindle 13, on which the adjustment force of the motor 11, 12 also acts according to the selected BKV amplification. Both forces together result in the force acting on the piston. If a rapid piston return occurs during pressure reduction for the ABS control, this acts on the pedal in a damped manner via the spring 20. A 10 bar pressure reduction in the control cycle corresponds to approx. 0.5 mm 10% of the spring travel in a medium class vehicle.

0038] Thus the pedal stroke is correspondingly greater than the piston stroke. The spring 20 can also be slightly preloaded for a corresponding pedal characteristic. This can use different strokes to increase the braking force, in that the pressure is proportional to the differential travel.

This travel is obtained from the signals of 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 line. The brake actuation device 16, 16a, 14 is permanently in contact with the drive via the Fe- of the 20 during braking. According to the desired amplification, the corresponding force is transmitted from the motor to the piston 24 via 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 tappet 21. The tappet 21 is coupled to the push rod piston 24 as well as to the spindle 13, so that high pressure gradients can be realized even at low pressures. The tappet has the task of not transferring the possible offset of the spindle 13 and impact of the ball screw gear to the push rod piston 24. The spin-del torque support 27 runs in a groove in the housing, preferably with good sliding properties, corresponding to the piston travel. The torque support is 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.

0039] The piston or actuator reset is done by the motor. In order to reduce additional load on the ball screw drive in case of a faulty reset and a hard stop, a cup spring 23 is provided between the torque support 27 and the ball screw drive 28. Usually, the actuating device is protected by an elastic bellows 29 against the ingress of dirt.

0040] Fig. 2 shows a third and fourth possible version of the brake system according to the invention. There is a rigid coupling between piston 24 and spindle 13 in that the tappet 21 is designed as a ball joint on both sides. On the right side of the spindle a corresponding insert 30 is screwed in.

0041] On the side of the brake actuation device 16, 16a, 14, the spring 20 is mounted in a corresponding design of the pedal transmission device 14, whose guide web 14a actuates the pedal travel sensor 22. The spring 20 acts on a collar 31a of a bearing part 31 with the return spring 17 inside. This bearing part is additionally guided in a bore.

0042] The transmission device 14 is additionally designed as a piston which is supported and sealed in the housing 15. The piston chamber is connected to the reservoir tank via a control valve 33 and 33a.

bind. The valve is used to block the pedal travel by means of the transmission device 14. If an HZ piston return for pressure reduction occurs, it acts on the spring 20 and not on the pedal 16, since when the solenoid valve 33, 33a is blocked, only a movement within the fluid compression can take place. The return flow from the piston chamber is closed by solenoid valve 33. If the piston travel is greater than the spring travel, e.g. in case of a jump in the friction coefficient, the solenoid valve 33, 33a is opened by evaluating the difference between piston travel and pedal travel. In the lower half of the picture, the pedal forward movement is blocked for the same purpose by not being able to increase the pedal travel.

0043] Fig. 3 shows a fourth possible version of the brake system according to the invention. Fig. 3a shows a cross-sectional view corresponding to the section x-x according to Fig. 3. In this design, an electromechanical pedal lock is implemented. The transmission device 14 is supported in the housing 15a (see Fig. 3a) via webs 14a. A magnet yoke 34 with return 36 is vertically floating in the housing 15a. The magnetic flux generated by coil 35 flows through yoke 34, return 36 and webs 14a and generates a frictional force for blocking the pedal in the respective directions. To increase the frictional force, magnetically conductive lamellas can be used in the known technique. The pedal locking force can be varied by variable current. It is also possible to generate a small pedal reaction by switching on the electromagnetic pedal lock only after a certain piston travel. This blocking is switched off again when the piston has been returned to the initial position before the pressure was reduced. The upper half of the picture shows how a progressive spring characteristic curve can be created by several springs (20, 20b) and a spring washer 20a.

0044] Fig. 4 shows a further design of the brake system according to Fig. 2 and Fig. 3 without the pedal lock with the aim of being able to generate pressure even if the drive is locked. This is made possible by the fact that the transmission device 14 transmits the pedal force to the tappet 21 and when the brake force amplification is active, the spindle forces also act on the HZ piston 24via the driver element 41. If the brake booster fails, however, only the pedal force acts.

0045] If a piston reset is now performed for pressure reduction for ABS, the solenoid 39 becomes active and moves the clutch element 40 in front of the plunger collar 21a. The spindle force is thus transmitted to the plunger 21 and acts against the transmission device 14, thus enabling

Pressure reduction in the corresponding brake circuit. In this design, the solenoid 39 with the spin-del 13 is movably mounted and requires a flexible connection 39a.

0046] It makes sense if the clutch is only effective if the motor function is intact before the pressure is built up. This prevents an ABS signal from being generated during the pressure build-up in the event of an explosion if the drive is blocked and the clutch is then engaged despite the drive being blocked, which would then lead to a blocking of the actuating device.

0047] The spindle 13 and the transmission device 14 have a radial offset and spindle runout due to tolerances. In order to avoid any load on the spindle 13 when the transmission device 14 acts on the tappet 21, the tappet 31b connected to the transmission device 14 should either be flexible and elastic as shown in the upper half of the figure or articulated 31c, especially by means of a ball joint, connected to the transmission device 14 (lower half of the figure).

0048] Fig. 4a shows an alternative design in which the solenoid is attached to housing 15 with coil 44. 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 bolt 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 pushes 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 design is less stressed, since the sleeve 42 reduces the tension here. The sleeve 42 must be axially fixed by means of a fixing ring or spring 48, since in the event of failure of the BKV, the sleeve 42 is moved in the spindle bore in accordance with the pedal stroke. Sleeve 42 and coupling element 40 can be cone-shaped. This means that even in the event of an extremely rare failure of the drive during ABS control, the release forces are lower when solenoid 44 is switched off.

0049] Fig. 5 shows the brake pressure p, sensor voltage U, piston travel sK and pedal stroke SP with suspension. Corresponding to the counterforce-dependent deflection, a differential travel Δh is created, which leads to a pressure p1 at a small pedal stroke and to a pressure p2 at maximum deflection with Δhmax. This function can be made linear or degressive with an appropriate spring.

0050] Electromotive brake boosters corresponding to the aforementioned state of the art, in particular

are redundant sensors for the angle of rotation of the motor or piston travel sK and pedal stroke s, since the sensors are safety-critical, especially in travel simulator systems, since, among other things, pedal stroke and piston travel are unequal. With the system according to the invention, the expenditure for the otherwise usual redundancy can be reduced or dispensed with by a plausibility comparison. For example, if the encoder for determining the pedal stroke fails, there is no differential travel Δh, which means that no BKV effect is controlled. However, the pedal acts on the piston as in the case of a failure of the BKV. From the piston travel sK value the error is recognized by the plausibility comparison. The same applies to sK. If the Δh calculation fails, a comparison of the pedal stroke sP with the measured pressure or current helps.

0051] The voltages of the sensors must be normalized or adjusted to a reference point due to different output voltages. It is suggested to perform an adjustment of the voltages in the initial position under consideration of a correction value, which can be e.g. the empty path Δs. This is device-specific and can be determined during the commissioning of the vehicle in production or service.

0052] 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 amplification K results at s1 to

For linear Fe- the gain K can be linear if Δh is proportional to the pressure or the piston force.

0053] Fig. 5b shows a brake circuit failure. No brake pressure is generated up to SA because the dropped brake circuit causes the pedal to fail up to SA. Afterwards, the piston counterforce acts and a Δh to the BKV function is created again, as described in Fig. 5. Here, for example, the amplification can be increased, since at the same pressure a smaller brake force is produced in total according to the failure of the brakes.

0054] In hybrid vehicles, variable amplification, in particular lower amplification, can also be used to compensate for the additional braking effect of the generator in the event of recuperation.

0055] The following are further examples of the invention:

Execution example 1:

0056] Brake system, having 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 to the latter for pressure reduction in ABS mode, the working chamber(s) of the brake booster being connected to the wheel cylinders of wheel brakes 9a-9d via hydraulic lines 6, 7 and a controllable valve 8a for each wheel brake 9a-9d, 8b, 8c, 8d, and in that, by means of a control device, a pressure build-up and pressure reduction in the wheel brakes 9a-9d takes place simultaneously and/or successively by means of the brake booster and the controlled valves 8a-8d, a brake actuation device 16, 16a, 14 acting in normal braking operation in a force-supporting manner on the spindles 13 and/or the piston 24 of the brake booster.

Execution example 2:

0057] Brake system according to design example 1, whereby in ABS operation the spindle 13 or the piston 24 applies force to and/or adjusts the brake actuation device 16, 16a, 14.

Execution example 3:

0058] Brake system according to design 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.

Execution example 4:

0059] Braking system according to one of the design examples 1 to 3, whereby the spring element 20 is supported with its one end on a transmission device 14 or the pedal tappet 16a and with its other end on the spindle 13, the piston 24 or the piston rod 21.

Execution example 5:

0060] Brake system according to design example 3 or 4, whereby the at least one spring element 20 has a linear or degressive force/travel characteristic curve for the upper force range.

Execution example 6:

0061] Brake system according to one of the design examples 3 to 5, whereby the spring travel length for maximum brake pressure is at least 1 mm, preferably at least 4 mm.

Execution example 7:

0062] Brake system according to one of the preceding design examples, wherein the brake actuation device has a brake pedal 16 which is connected to a pedal tappet 16a, wherein the pedal tappet 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.

Execution example 8:

0063] Brake system according to design example 7, whereby the at least one spring element 20 is arranged in or on the transmission device 14.

Execution example 9:

0064] Brake system according to one of the previous examples, whereby an additional return spring element 17 lifts the transmission device 14 or the pedal tappet 16a from the piston 24 or the spindle 13.

Execution example 10:

0065] Brake system according to one of the preceding examples, whereby piston 24 and spindle 13 are connected permanently or optionally, in particular by means of a switchable clutch 40-46, or can be connected or disconnected optionally.

Execution example 11:

0066] Brake system according to design example 10, whereby the piston 24 and the spindle 13 can be connected to each other either by means of positive or frictional locking.

Execution example 12:

0067] Brake system according to design example 10, wherein the piston 24 and the spindle 13 are connected or can be connected to each other by means of a force transmission means, in particular in the form of a tappet 21, which can be designed as a bending bar.

Execution example 13:

0068] Brake system according to one of the design examples 10 to 12, wherein the power 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 the power transmission means 21 can be adjusted for pressure build-up with the spindle 13, and that the brake actuating device 16, 16a, 14 is arranged in the direction of the pressure build-up.

In order to remove the spindle, either a positive or a frictional connection between the power transmission device 21 and the spindle 13 can be established by means of the coupling 40-46.

Execution example 14:

0069] Brake system according to design example 13, whereby when the clutch 40-46 is engaged, the positive connection for adjusting the force transmission medium 21 for pressure reduction or for retracting the piston 24 is made by a coupling element 40, which serves in particular as a stop for the force transmission plunger 21, whereby the coupling element 40 extends through the cylindrical wall of the spindle 13.

Execution example 15:

0070] Brake system according to one of the design examples 10 to 14, where the clutch 40-46 is a "one-way" system.

The drive 44, 46, 47, which is fixed to the housing, adjusts the coupling element 40, whereby the coupling element 40 can be moved relative to the drive 44 parallel to the spindle axis.

Execution example 16:

0071] Brake system according to one of the design examples 10 to 15, where the clutch 40-46 has a

drive 44, 46, 47 for adjusting the coupling element 40, whereby the drive is attached to spindle 13.

Execution example 17:

0072] Brake system according to one of the design examples 10 to 16, whereby the coupling element 40 extends through the cylindrical wall of spindle 13.

Execution example 18:

0073] Brake system according to one of the design examples 10 to 17, whereby the clutch element 40 is force-actuated by a spring element 46 in the direction of the disengaged position.

Execution example 19:

0074] Braking system according to one of the design examples 10 to 18, whereby the control device closes the clutch 40-46 only if the motor function of the drive 11, 12 has been found to be OK beforehand.

Execution example 20:

0075] Braking system according to one of the previous examples, where the braking system is

The brake actuating device is provided with a locking device by means of which the movement of the brake actuating device can be blocked.

Execution example 21:

0076] Brake system according to design example 20 where the locking device can block the brake actuation device in any position or in a certain range of movement.

Execution example 22:

0077] Brake system according to design example 20 or 21, whereby 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.

Execution example 23:

0078] Braking system according to one of the design examples 18 to 20, whereby a control device controls the locking device depending on the signals of the ABS/ESP controller and the piston and actuator positions.

Execution example 24:

0079] Brake system according to one of the preceding design examples, the brake system having sensors for determining the piston position and the position of the brake actuation device, and the control device of the brake system controlling the drive of the brake booster in dependence of the two positions relative to each other.

Execution example 25:

0080] Brake system according to design example 24, wherein the control device determines the pedal force from the determined positions of piston 13 and brake actuation 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.

Execution example 26:

0081] Brake system according to one of the preceding examples, the brake system having a pressure sensor 10 with which the pressure in the pressure piston circuit can be determined, the pressure control for the wheel brakes 9a-9d being based on the pressure volume characteristic curves.

Execution example 27:

0082] Brake system according to one of the design examples 1 to 25, the current intensity proportional to the pressure being 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 being carried out on the basis of the pressure volume characteristics and the current intensity, in particular without using a pressure sensor.

Execution example 28:

0083] Brake system according to one of the preceding design examples, whereby the control device carries out a plausibility check for the state variables "brake actuation device, in particular pedal stroke sP, and piston control sK.

Execution example 29:

0084] Brake system according to one of the preceding examples, whereby the control device carries out a standardization and adjustment of the sensor signals, in particular for the pressure, position and/or angle of rotation sensors, whereby the adjustment is carried out in the initial position of brake pedal 16, spindle 13 and piston 24, taking into account the previously determined real distance Δs as correction value.

Execution example 30:

0085] Braking system according to one of the preceding examples, where the control device uses the spring travel of spring 20 as a control variable for the adjustment of the brake booster.

Execution example 31:

0086] Brake system according to one of the previous examples, whereby the return springs of the HZ- or THZ move the piston 24 and the spindle 13 to their initial position.

Execution example 32:

0087] Brake system according to one of the previous examples, whereby a spring 3 forces the spindle 13 in the direction of its initial position and the HZ or THZ springs force the piston 24 into its initial position.

Execution example 33:

0088] Brake system according to one of the previous examples, whereby the brake system connected to the over-loader

the support device 14 or the piston system 24,

21, 30 a bearing part 31 is displaceably mounted parallel to the spindle axis, whereby the bearing part 31 has a flexurally elastic tappet 31b for power transmission to the piston system or the transmission device 14.

Execution example 34:

0089] Brake system according to design example 33, whereby the tappet 31c is linked to the load-carrying part 31 by means of a ball joint.

Execution example 35:

0090] Braking system according to one of the preceding examples where the control device adjusts the brake force amplification depending on the braking effect achieved by means of recuperation.

 

1 EC motor

2 Spindle

3 Spindle reset

4 Angle of rotation encoder (position encoder)

5 HZ or THZ

7 Pressure line from push rod piston

8 Pressure line from floating piston

8a-8d2/2 magnetic valves as switching valves

9a-9d wheel cylinder

10 Pressure transmitter

11 Stator

12 Rotor

13 Spindle

14 Transmission device

14a Guide bar

15 Housing

15aHousing bearing for transmission device

16 Brake pedal

16a Pedal ram

17 Return spring

18 Disc

19 Circlip

20 Pressure spring

20a Spring washer

20 Second pressure spring

21 Tappet

21a Roller collar

22 Pedal stroke sensor

23 Disc spring

24 Push rod piston

25 Motor control

26 Shunt

27 Moment support

28 Ball screw drive

29 Bellows

30 Insert

31 Stock section

31a Collar of the bearing part

31elastic tappet

31c-joint plunger

32 Drill

33/33a2/2 Solenoid valve

34 Magnet yoke

35 Coil

36 Conclusion

37 magnetic flux

38 Slats

39 Stroke solenoid

39aflexible electrical connection

40 Coupling element

41 Drive element

42 Sleeve

43 Guide rail

44 Solenoid with coil

45 magnetic armature

45a Bearing bolt

46 Return spring

47 Storage

48 Spring

 

Claims

 

1. Brake system, having 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 with a spindle (13), wherein the working chamber or chambers of the brake booster are connected via hydraulic lines (6, 7) to the wheel cylinders of wheel brakes (9a-9d) and a controllable valve (8a-8d) is associated with each wheel brake (9a-9d), and in that, by means of a control device, a pressure build-up and pressure reduction in the wheel brakes (9a-9d) takes place simultaneously or successively by means of the brake booster and the controlled valves (8a-8d),characterized in that a brake actuation device (16, 16a, 14) acts in a force-supporting manner on a piston (24) of the brake booster in normal braking operation, wherein in ABS operation the spindle (13) or the piston (24) applies and/or adjusts the brake actuation device (16, 16a, 14) and the piston (24) of the brake booster is moved back and forth by means of the electric motor (11, 12) for adjusting the wheel brake pressures.

 

2. Brake system according to claim 1, characterized in that the actuating device (16, 16a, 14) acts via at least one spring element (20, 20b) on the spindle (13) and/or the piston (24) of the brake booster.

 

3. Braking system according to claim 2, characterized in that the at least one spring element (20, 20b) is located with its one end at a

 

transmission (14) or a pedal pusher (16a) and with its other end supported on the spindle (13), the piston (24) or a pusher (21).

 

4. Braking system according to claim 2 or 3, characterized in that the at least one spring element (20, 20b) has a linear or degressive force-displacement characteristic curve for the upper force range.

 

5. Braking system according to one of claims 2 to 4, characterized in that the spring travel length of the at least one spring element (20, 20b) for maximum brake pressure is at least 1 mm.

 

6. A brake system according to claim 1, characterized in that the brake operating device comprises a brake pedal (16) which is in communication with a pedal tappet (16a), said pedal tappet (16a) being connected to a transmission device

(14) is connected and the transmission device

(14) acts on the piston (24) of the brake booster.

 

7. Braking system according to claim 6, characterized in that the at least one spring element (20, 20b) is arranged in or on the transmission device (14).

 

8. Braking system according to any one of claims 3 to 7, characterized in that an additional return spring element (17) supports the transmission device (14) or the pedal tappet (16a) of the piston

(24) or the spindle (13) lifts.

9. A brake system according to one of the preceding claims, characterized in that the brake system comprises a locking device by means of which the movement of the brake actuation device (16, 16a, 14) can be blocked.

 

10. Brake system according to claim 9, characterized in that the locking device can lock the brake actuation device (16, 16a,14) in any position or in a certain range of motion.

 

11. Brake system according to claim 9 or 10, characterized in that the locking device is hydraulically or electrically driven and is connected to the brake actuation device (16, 16a,

14) is effective.

12. Braking system according to one of claims 9 to 11, characterized in that a control device controls the locking device in dependence on the signals from an ABS/ESP controller and the piston (24) and actuating device positions.

 

 

 

13. Brake system according to one of the preceding requirements, characterized in that the brake system has sensors for determining the piston position and the position of the brake actuation device (16, 16a, 14), and the control device controls the electric motor (11, 12) as a function of the two positions relative to one another.

 

14. Brake system according to claim 13, characterized in that the control device determines the pedal force from the determined positions of piston (24) and brake actuation device (16, 16a, 14) and controls the electric motor (11, 12) on the basis of the differential stroke Δh proportional to the pedal force.

 

15. Brake system according to one of the preceding claims, characterized in that the brake system has a pressure sensor (10) with which the pressure in the pressure piston circuit can be determined, the pressure control for the wheel brakes (9a-9d) being based on pressure volume characteristics.

 

16. Brake system according to claim 15, characterized in that the current intensity proportional to the pressure is measured by means of the current consumption of the electric motor (11, 12) 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.

 

17. Brake system according to one of the preceding claims, characterized in that the control device carries out a plausibility check for measured variables relating to a pedal stroke sP and/or a piston position

 

18. Braking system according to one of the preceding requirements, characterized in that the control device uses the spring travel of the at least one spring element (20, 20b) as a control variable for the adjustment of the brake force amplification.

 

19. Brake system according to one of the preceding claims, characterized in that return springs of the master brake cylinder or tandem master brake cylinder (5) move the piston (24) as well as the spindle (13) into their initial position.

 

20. Brake system according to one of the preceding claims, characterized in that a spindle return spring (3) forces or displaces the spindle (13) in the direction of its initial position and return springs of the master brake cylinder or tandem master brake cylinder (5) force the piston (24) into its initial position.

 

21. Braking system according to one of the preceding claims, characterized in that the control device controls the brake force amplification in downhill and uphill directions.

 

The braking effect achieved by means of recuperation is adjusted according to the degree of dependency.