Electromechanical brake booster

Abstract

Electromechanical brake booster, comprising: a push rod (21) for coupling a brake pedal lever to a master brake cylinder, a gear motor (22) which is coupled to the push rod (21), and a control device (29) which is connected to the gear motor (22) for controlling the same, characterized in that the control device (29) are connected as input variables: - a pedal force quantity representing the pedal force, and - a push rod movement quantity representing the movement of the push rod, and that the control device (29) is configured to: - using the push rod movement size, a target return speed (v Psoll ) for the push rod (21), and - from the target return speed (v Psoll ), an actual return speed (v Pist) of the push rod (21) and the pedal force a control signal (i M ) for the geared motor (22).

Description

[0001] The invention relates to an electromechanical brake booster, comprising a push rod for coupling a brake pedal lever to a master brake cylinder, a gear motor which is coupled to the push rod, and a control device which is connected to the gear motor for controlling the same.

[0002] One such system is known, for example, from DE 10 2007 032 501 A1. Due to the connection of the brake pedal lever to the master cylinder, unlike systems with a pedal simulator, the foot force applied by the driver can be used directly to build up brake pressure in the master cylinder. The electromechanical brake booster can apply force both in the direction of the foot force and in the opposite direction, for example, to assist the driver during braking or to facilitate the return of the brake pedal lever to its original position.

[0003] Due to friction and hysteresis effects, the hydraulic pressure in the master cylinder can cause the brake pedal lever to return more slowly than desired. Another problem sometimes arises when the push rod speed is too high toward the end of the return movement, resulting in high impulse forces at the end stop for the brake pedal lever's initial position. This is primarily caused by the system's return springs, which provide a defined response force in the brake pedal lever's initial position. This is generally perceived as positive for pedal feel and is adjusted according to the brand and vehicle.

[0004] In this context, DE 10 2007 032 501 A1 proposes that when a pedal force F P=0 at the brake pedal lever in the brake booster to generate a negative assist force that opposes the usual actuation of the brake pedal lever, which, as the pedal force increases, transitions into a positive assist force that supports the pedal force. This eliminates the need for a mechanical return spring within the brake booster or makes it considerably softer and less preloaded. The force required for optimal response is actively generated by the brake booster. For this purpose, an assist characteristic curve is provided that adjusts the assist force of the brake booster depending on the detected pedal force F P pretends.

[0005] Furthermore, DE 10 2012 209 157 A1 shows a control device for a braking system with at least one electric brake in an electric drive system and at least one mechanical service brake, in particular for electrically powered vehicles or hybrid vehicles.In order to optimize energy efficiency, cost-effectiveness and driver ergonomics, a control device is proposed which provides a brake pedal actuating force control for determining a brake pedal actuating force setpoint for generating a brake pedal restoring force on a brake pedal by means of a brake pedal actuator as a function of a brake pedal actual value of the deflection of the brake pedal detected by a brake pedal sensor and / or a maximum available electrical braking torque and / or a currently available electrical braking torque and / or a maximum recuperable electrical braking torque of the electric brake and / or a brake pedal actuating force actual value of the brake pedal actuator.Furthermore, a brake control for generating a mechanical brake force setpoint and an electrical brake force setpoint as a function of the brake pedal actual value detected by the brake pedal sensor and / or a brake pedal intervention point of the mechanical service brake determined by the brake pedal actuating force control and / or an electrical brake force actual value of the electric brake is provided for the control device.

[0006] Based on this, the present invention is based on the object of further improving the return of the brake pedal lever.

[0007] This object is achieved by an electromechanical brake booster according to claim 1. The electromechanical brake booster according to the invention comprises a push rod for coupling a brake pedal lever to a master brake cylinder, a gear motor which is coupled to the push rod, and a control device which is connected to the gear motor for controlling the same.It is characterized in that a variable representing the pedal force, hereinafter referred to as "pedal force variable", and a variable representing the movement of the push rod, hereinafter referred to as "push rod movement variable", are applied to the control device as input variables, and in that the control device is configured in such a way as to determine a target return speed for the push rod by means of the push rod movement variable and, if applicable, further influencing variables, and to generate a control signal for the geared motor from the target return speed, the actual return speed of the push rod and the pedal force variable.

[0008] This can improve the brake release behavior and reduce high impulse forces at the end stop.

[0009] In particular, an active return of the push rod of the brake booster and thus of the brake pedal lever to the respective starting position can be achieved, which can be individually adjusted to suit the brand and vehicle without great effort if required.

[0010] Advantageous embodiments of the invention are the subject of further patent claims.

[0011] For example, the control device can be configured to determine a difference between the target return speed and the actual return speed and to generate a control signal for the gear motor depending on this difference and the pedal force value.

[0012] To determine the target return speed, a characteristic curve can be stored, for example, in the control unit, which specifies the target return speed depending on the position of the brake pedal lever. The position of the brake pedal lever can be detected via the position of the push rod, the position of the gear motor, or some other means. This makes it possible to specify a different return speed for the brake pedal lever depending on its position. In this way, the transition of the brake pedal lever into other movement ranges, such as the end position or clearance compensation, can be designed in such a way that no haptic or acoustic abnormalities arise.

[0013] To determine the target return speed, the pedal force can also be taken into account in addition to the push rod movement.

[0014] Preferably, the control signal of the geared motor is a quantity representing the motor torque.

[0015] Furthermore, the control device can be configured such that the control signal of the geared motor is limited to a predefined value range for the return movement of the push rod. Furthermore, the gradient of the control signal can also be limited within the predefined value range. This can prevent perceived unnatural push rod return movements.

[0016] According to a further advantageous embodiment of the invention, a sensor is provided to detect the push rod movement magnitude. This sensor interacts with the push rod or the brake pedal lever. Such a sensor can, for example, detect the absolute position. Furthermore, the movement speed can be derived from this if necessary. However, it is also possible to detect corresponding position information regarding the position and speed of the push rod in other ways.

[0017] According to a further advantageous embodiment of the invention, a sensor is provided for detecting the pedal force magnitude. This sensor can be a force sensor arranged on the push rod or the brake pedal lever, or a pressure sensor for detecting the pre-pressure generated by the master brake cylinder. If necessary, the data from both a force sensor and a pressure sensor can be taken into account in determining the pedal force magnitude.

[0018] To generate the control signal, a factor for the difference between the target return speed and the actual return speed and for the pedal force value can be determined by means of characteristic curves stored in the control device, which are multiplied with one another in order to obtain the control signal for the gear motor in a particularly simple manner.

[0019] Furthermore, a temperature signal can be incorporated into the generation of the control signal. This makes it possible to compensate for temperature-related effects. Especially at low temperatures, system friction can increase and alter the return behavior of the brake pedal lever.

[0020] Preferably, the component temperature is measured in the surrounding area or directly at the brake pedal lever. If necessary, temperature sensors installed on the brake booster can also be used for temperature measurement.

[0021] The temperature signal is preferably taken into account in such a way that the return of the brake pedal lever is the same at every temperature.

[0022] Furthermore, a signal representing the vehicle speed can be included in the generation of the control signal.

[0023] Furthermore, another factor can be incorporated into the generation of the control signal, which can be adjusted by the driver to influence the characteristics of the push rod return. This allows the driver to select, for example, a sportier or more comfortable pedal characteristic as desired.

[0024] The invention is explained in more detail below with reference to exemplary embodiments illustrated in the drawing. The drawing shows: Fig. 1 shows an electromechanical brake booster coupled between a brake pedal lever and a tandem master cylinder of a vehicle brake system according to an embodiment of the invention, Fig. 2 a schematic representation of the control of the gear motor of the electromechanical brake booster, Fig. 3 a schematic representation of a variant of the control of the gear motor of the electromechanical brake booster, and in Fig. 4 a schematic representation of another variant of the control of the gear motor of the electromechanical brake booster, and in Fig. 5 a schematic representation of a third variant of the control of the gear motor of the electromechanical brake booster.

[0025] The embodiment in Fig. 1 shows a vehicle brake system with a master brake cylinder 10, an electromechanical brake booster 20 and a brake pedal lever 30. The tandem master brake cylinder 10 is connected to an ESP hydraulic unit 40, via which wheel brakes of the individual vehicle wheels are controlled.

[0026] The master brake cylinder 10 is connected to the hydraulic unit 40 via two brake circuits 11 and 12. The two brake circuits 11 and 12 are controlled by a first floating piston 14, supported by a first return spring 13, and a second primary piston 18, supported by a second spring 17. The first spring 13 serves to push the floating piston 14 back so that brake fluid can flow from an expansion tank 15 into a first pressure chamber 16 of the master brake cylinder 10. In the event of a leak in the second hydraulic brake circuit 12, the additional spring 17 serves to separate the floating piston 14 from the primary piston 18, so that brake fluid can flow from the expansion tank 15 into an additional pressure chamber 19 between the floating piston 14 and the primary piston 18. The springs 13 and 17 are designed to ensure that both pistons 14 and 18 return to their original position in all driving situations. The springs 13 and 17 are designed to ensure that both pistons 14 and 18 return to their original position in all driving situations. Fig. The master brake cylinder 10 shown in Figure 1 is merely exemplary. Within the scope of the present invention, other types of master brake cylinders 10 that are compatible with an electromechanical brake booster 20 can also be used.

[0027] The electromechanical brake booster 20 according to the invention has a push rod 21 for connecting the master brake cylinder 10 to the brake pedal lever 30. This connection is preferably designed such that both compressive and tensile forces can be transmitted between the master brake cylinder 10 and the brake pedal lever 30. As in particular Fig. 1 can be removed, the push rod 21 engages the primary piston 18 of the master brake cylinder 10.

[0028] Furthermore, the electromechanical brake booster 20 has a gear motor 22 which is coupled to the push rod 21. In Fig. 1 shows a brushless electric geared motor 22 purely as an example. This has a stator 23 and a rotor 24, which are arranged concentrically around the push rod 21. A spindle drive of the geared motor 22, which is also arranged coaxially to the push rod 21, comprises a spindle screw 25 that is mounted in a rotationally fixed manner but is axially movable and is firmly connected to the push rod 21. The spindle screw 25 meshes via balls with a ball screw nut 26, which is driven via the rotor 24 of the geared motor 22. Instead of the geared motor type shown, however, other electric drives can also be used, which allow the conversion of a torque into an axial force on the push rod via a rotation-translation gear.

[0029] When the gear motor 22 is activated, the ball screw nut 26 is rotated to generate a positive or negative force in the axial direction of the spindle screw 25 and thus on the push rod 21, depending on the direction of rotation. A positive force is understood to be a force that points in the same direction as the pedal force F generated by the driver on the brake pedal lever 30 when braking. P A negative force points in the opposite direction and thus acts on the pedal force F P of the driver.

[0030] In amplifier mode, the push rod 21 is actuated by the pedal force F P and a positive assist force provided by the gear motor 22 in the direction of the master brake cylinder 10, ie in Fig. 1 to the left. Here, the pedal force F applied by the driver Pfor example, with a force sensor 27 on the piston rod 21. Alternatively or additionally, the pre-pressure generated by the master brake cylinder can also be detected by means of a pressure sensor 41. Depending on the detected force, the coils of the stator 23 of the geared motor 22 are energized. As a result, the rotor 24, which is provided, for example, with permanent magnets, begins to rotate. Via the ball screw nut 26, which is firmly connected to the rotor 24 or formed as one piece, and the balls of the ball screw drive, the spindle screw 26 and the push rod 21 move in a translational movement towards the master brake cylinder 10. For this purpose, the spindle screw 26 is mounted in a rotationally fixed but translationally free manner.

[0031] If the electromechanical brake booster 20 is not working or loses power, the driver can apply the brakes using their foot alone. To enable the brake pressure to be reduced to zero after a brake application, the drive of the electromechanical brake booster 20 can be designed to be non-self-locking. In particular, it can be configured such that the hydraulic counterpressure, the spring system of the master brake cylinder 10 with springs 13 and 17, and any pedal return spring 28 present in the brake booster 20, generate a sufficient restoring force to return the electromechanical brake booster 20 and the brake pedal 30 to the unbraked position.

[0032] This return movement can be assisted by the electromechanical brake booster 20. As already explained, with the electromechanical brake booster 20 described above, opposing assist forces can be provided by reversing the direction of rotation of the gear motor 22.

[0033] The invention is expressly not limited to a brake booster of the type with a geared motor 22 according to the specific embodiment of Fig. 1. Rather, other configurations and mechanical concepts can also be used to introduce the assist force. Further examples of coupling an electric motor via a gear to the push rod 21 are disclosed in German patent applications Nos. 10 2014 226 248.8 and DE 10 2014 226 255.0, each entitled "Electromechanical Brake Booster," the relevant content of which is hereby incorporated into the present application. As described therein, the gear mechanism of the geared motor can, for example, have a crank disc and at least one lever, preferably two levers interacting with the crank disc.Furthermore, a transmission device is possible in which an electric drive motor drives a cam disk whose circumference engages with the push rod 21 to press it towards the master brake cylinder in order to specify a variable transmission ratio between the translation speed of the push rod and the speed of the drive motor.

[0034] For the active return of the push rod 21 to the unactuated initial position, a control device 29, for example a control unit of the electromechanical brake booster 20, which is described below with reference to the Fig. 2 and Fig. 3 is implemented. This algorithm uses the pedal force F as input variables. P representing pedal force quantity and a push rod movement quantity representing the movement of the push rod.

[0035] The pedal force value representing the pedal force is preferably the output signal of the force sensor 27. However, the signal of the pressure sensor 41 can also be evaluated for this purpose. In principle, all signals can be used which allow a conclusion to be drawn about the pedal force F P on the push rod 21.

[0036] The push rod movement variable representing the movement of the push rod 21 is preferably detected by a sensor 50 that interacts with the push rod 21 or the brake pedal lever 30. The absolute position s P in relation to the unactuated initial position. Furthermore, the actual movement speed of the push rod 21 can be derived from this, if necessary, which, in the event of a brake release, is referred to below as the actual return speed v PistHowever, it is possible to acquire corresponding position information about the position and speed of the push rod 21 in other ways, for example and without limitation by evaluating the signals of a rotor position sensor of the geared motor 22.

[0037] The aforementioned variables, namely the pedal force and the push rod movement, are applied to the control device 29 as input variables. For this purpose, sensors 27 and 50, and possibly also sensor 41, are connected to the control device 29 via signals.

[0038] The control device 29 is configured in such a way as to calculate a target return speed v from the pedal force value and the push rod movement value as well as optionally further influencing variables. Psollfor the push rod 21. This can be done, for example, with the aid of characteristic curves, characteristic maps and / or other calculation rules stored in the control device 29.

[0039] From the target return speed v Psoll and the actual return speed v Pist the push rod 21, a difference Δv is then determined in the control device 29.

[0040] Depending on this difference Δv and the pedal force magnitude, a control signal i M for the geared motor 22, which is preferably a variable representing the motor torque of the geared motor 22.

[0041] About the target return speed v PsollA desired return behavior of the push rod 21 when the brake is released can be specified. Any deviations are corrected by appropriately controlling the electromechanical brake booster 20. This compensates for friction and hysteresis losses. Furthermore, deviations in the return forces of the springs 13, 17, and 28 can be compensated. Under certain circumstances, individual springs can also be substituted by the electromechanical brake booster 20.

[0042] Since the position of the push rod 21 is included in the control of the gear motor 22, the return speed of the push rod 21 can be specifically reduced before the end stop for the initial position of the brake pedal lever 30 is reached, so that high impulse forces at the end stop are avoided.

[0043] Fig. Figure 2 shows an example of the algorithm according to the invention, in which the pedal force F Pof the force sensor 27 and as push rod movement quantity the absolute position s P in relation to the unactuated initial position of the push rod 21, measured by the sensor 50. In a first block 60, the target return speed v is calculated from this using predefined calculation rules. Psoll In parallel, in a second block 61, the path variable s is mathematically derived P the actual return speed v Pist In a further operation 62, the difference Δv from the target return speed v Psoll and the actual return speed v Pist calculated.

[0044] To generate the control signal, a first characteristic curve 63 for the difference Δv from the target return speed v Psoll and the actual return speed v Pist a first factor f1 is determined. In parallel, the pedal force F PA second factor f2 is determined by means of a second characteristic curve 64. By multiplying 65 the factors f1 and f2, the control signal i is obtained M for the gear motor 22.

[0045] Furthermore, the control device 29 can be configured such that for the return of the push rod 21 the control signal i M of the geared motor 22 is limited to a specified range of values. In addition, the gradient of the control signal i M be limited. In Fig. 2, a limiting device 66 is provided for this purpose, which limits the control signal i M accordingly on i Mlimit limited before it is fed to the gear motor 22.

[0046] Fig. Figure 3 shows a variant of the algorithm implemented in the control device 29. In this variant, the generation of the control signal i Ma further factor f3, which can be adjusted by the driver to influence the characteristics of the push rod return. Preferably, this factor f3, for which a corresponding calculation rule 67 is provided in the control device 29, is included in the multiplication 65 of the other two factors f1 and f2. The adjustment can be made, for example, by a switch in the passenger compartment of a motor vehicle or by a correspondingly selectable function in an on-board computer, which is used as a further input signal i F the control device 29. This allows the driver to select, for example, a sportier or more comfortable pedal characteristic as desired.

[0047] Fig. Figure 4 shows a further variant of the algorithm implemented in the control device 29. This again uses a pedal force value and a push rod movement value as input variables. Furthermore, a temperature signal T and / or a vehicle speed v are optionally input. F representing signal is used as input variables.

[0048] As above, the pedal force F can be used as the pedal force quantity. P of the force sensor 27 Fig. 1. The push rod movement variable is preferably a variable which corresponds to the absolute position s P of the brake pedal lever, for example, in relation to its unactuated initial position. For this purpose, as in Fig. 1, a sensor 50 can be used to detect the absolute position of the push rod 21 or the brake pedal lever 30. It is also possible to determine the position of the brake pedal lever 30 by detecting the motor position of the gear motor 22.

[0049] In a first block 60', the desired return speed v Psoll This can be done by means of calculation rules stored in the control device 29. In particular, a characteristic curve can be stored in the control device 29 which determines the desired return speed v Psoll depending on the position of the brake pedal lever 30 or the detected push rod movement size, in this case s P , specifies the desired return behavior. The characteristic curve can be easily set and modified by reprogramming the characteristic curve in software. This allows a type- or model-specific brake pedal feel to be generated for different vehicle types or models using the same hardware.

[0050] In determining the target return speed v PsollOptionally, the pedal force, the temperature signal T and / or the vehicle speed v F representing signal should be included.

[0051] In parallel to the determination of the target return speed v Psoll will be as in the Fig. 2 and Fig. 3 in a second block 61 by mathematical derivation of the path size s P the actual return speed v Pist In a further operation 62, the difference Δv from the target return speed v Psoll and the actual return speed v Pist calculated.

[0052] To generate the control signal, a first characteristic curve 63 for the difference Δv from the target return speed v Psoll and the actual return speed v Pist a first factor f1 is determined. In parallel, the pedal force F PA second factor f2 is determined by means of a second characteristic curve 64. By multiplying 65 the factors f1 and f2, the control signal i is obtained M for the gear motor 22. Furthermore, as in Fig. 2 and Fig. 3 Means for limiting the control signal i M for gear motor 22 to a specified range of values.

[0053] Fig. 5 shows a further modification of the algorithm according to Fig. 4, where again the pedal force, the push rod movement and optionally a temperature signal T and / or the vehicle speed v F representing signal can be used as input variables.

[0054] In a first block 60', the desired return speed v is determined from the push rod movement variable by means of calculation rules, characteristic curves and the like provided in the control device 29. Psolldetermined as already explained above. Similarly, the value determined in block 61'.

[0055] A controller 70 is the target return speed v Psoll , which is the actual return speed v Pist , the pedal force quantity, in this case exemplified as pedal force and pedal force change rate, as well as the optional temperature signal T and the optional vehicle speed signal are applied as input variables. Based on these variables, a control signal i is then generated in the controller 70". M for the gear motor 22.

[0056] The consideration of these additional influencing variables can be used to calculate the control difference Δv from the target return speed v Psoll and actual return speed v Pist to modify and / or the target return speed v Psoll before determining the control difference Δv.

[0057] In one variant, the measured values ​​of pedal force, pedal force change rate, brake pedal position, and brake pedal speed (as variables representing the movement of the push rod) can be used as actual values ​​to control the return speed of the brake pedal lever at a specific brake pedal position based on a setpoint stored in a memory. The measured values ​​of brake pedal position and brake pedal speed can be derived, for example, from the motor position detection of the geared motor.

[0058] The inclusion of the pedal force and the pedal force change rate serves to detect the driver's request and, if necessary, to suppress the return of the brake pedal lever or to generate a damping effect on the driver's movement.

[0059] Furthermore, the control can be influenced by the vehicle speed, which is recorded via the vehicle bus.

[0060] In addition, the return speed can be adjusted depending on the temperature, in order to specifically meet the requirements of low temperatures. When the driver releases the previously depressed brake pedal lever, return springs ensure that it returns to its original position. This return process is primarily influenced by the spring force and the friction in the system. At low temperatures and correspondingly higher friction, the return speed can be very slow. At high temperatures, or the further the brake pedal lever is pressed, the faster the return speed becomes. If the brake pedal lever returns to its original and resting position at high speed, unpleasant noises can occur. Temperature sensors built into the brake booster can be used to measure the temperature. In the end position range, i.e.close to the starting and rest position of the brake pedal lever, a particularly slow and damped return can be achieved so that acoustic effects are minimized when the end position is reached.

[0061] Furthermore, clicking noises can be prevented by setting a specific return speed.

[0062] The invention explained above is based on a control system that influences the return behavior of the brake pedal lever and returns it to its initial position in a defined manner via the gear motor.

[0063] A dampened return to the starting position prevents annoying noises. Adjusting the target return speed also successfully combats cavitation noises in the hydraulic system of the master brake cylinder and clicking noises caused by play.

[0064] By storing target characteristics for the target return speed in a memory, adjustment to haptics and acoustics can be carried out using software without great effort.

[0065] The invention has been explained in more detail above using exemplary embodiments. However, it is not limited to these exemplary embodiments, but encompasses all embodiments defined by the claims. List of reference symbols 10 master brake cylinders 11 first brake circuit 12 second brake circuit 13 Return spring 14 floating pistons 15 Pressure reservoir 16 Printing room 17 additional return springs 18 primary pistons 20 electromechanical brake booster 21 Push rod 22 Gear motor 23 Stator 24 rotors 25 spindle screw 26 Ball screw nut 27 Pedal force sensor 28 Brake booster return spring 29 Control device 30 Brake pedal 40 ESP hydraulic unit 41 Sensor 50 sensors 60, 60' first block 61, 61' second block 62 Operations 63 first characteristic curve 64 second characteristic curve 65 Multiplication 66 Limiting device 67 Calculation rule 70 controllers f1 factor f2 factor f3 factor F P Pedal power i F additional input signal i M Control signal i Mlimit limited control signal s P Absolute value of the travel of the push rod relative to its unactuated initial position v Pist Actual return speed v Psoll Target return speed Δv Difference between target return speed and actual return speed

Claims

[1] Electromechanical brake booster, comprising: a pushrod (21) for coupling a brake pedal lever to a master brake cylinder, a geared motor (22) which is coupled to the push rod (21), and a control device (29) which is connected to the geared motor (22) for controlling it, characterized by , that are connected to the control unit (29) as input variables: - a pedal force quantity representing pedal force, and - a pushrod motion quantity representing the movement of the pushrod, and that the control device (29) is configured to: - by means of the pushrod movement quantity a target return speed (v Psoll ) to determine for the push rod (21), and - from the target return speed (v Psoll ), an actual return velocity (v Pist) the pushrod (21) and the pedal force magnitude a control signal (i M ) to generate for the geared motor (22). [2] Electromechanical brake booster according to claim 1, characterized by , that the control device (29) is configured to determine from the target return velocity (v Psoll ) and the actual return velocity (v Pist ) to determine a difference (Δv) and, depending on this difference (Δv) and the pedal force magnitude, a control signal (i) M ) to generate for the geared motor (22). [3] Electromechanical brake booster according to claim 1 or 2, characterized by , that to determine the target return velocity (v Psoll ) in addition to the pushrod movement size, the pedal force size is also taken into account. [4] Electromechanical brake booster according to one of claims 1 to 3, characterized by , that to determine the target return velocity (v Psoll) a characteristic curve is stored which specifies the target return velocity (v Psoll ) depending on the position of the brake pedal lever. [5] Electromechanical brake booster according to any one of claims 1 to 4, characterized by , that the control signal (i M ) is a quantity representing the engine torque. [6] Electromechanical brake booster according to any one of claims 1 to 5, characterized by , that the control device (29) is configured such that the control signal (i) is used for the return stroke of the push rod (29). Mlimit ) of the geared motor (22) is limited to a predetermined range of values. [7] Electromechanical brake booster according to claim 6, characterized by , that the control device (29) is configured such that the gradient of the control signal (i) is within the specified range of values Mlimit ) is limited. [8] Electromechanical brake booster according to any one of claims 1 to 7, characterized by , that a sensor (50) for detecting the pushrod movement size interacts with the pushrod (21) or the brake pedal lever. [9] Electromechanical brake booster according to any one of claims 1 to 8, characterized by , that a sensor for detecting the pedal force magnitude is a force sensor (27) arranged on the pushrod or the brake pedal lever or a pressure sensor (41) for detecting the pre-pressure generated by the master brake cylinder. [10] Electromechanical brake booster according to any one of claims 1 to 9, characterized by , that to generate the control signal by means of characteristic curves (63, 64) stored in the control unit (29) a factor (f1, f2) is used for the difference (Δv) from the target return speed (v Psoll ) and the actual return velocity (v Pist) and for the pedal force magnitude, which are multiplied together to determine the control signal (i M ) for the geared motor (22). [11] Electromechanical brake booster according to any one of claims 1 to 10, characterized by , that in the generation of the control signal (i M ) receives a temperature signal. [12] Electromechanical brake booster according to any one of claims 1 to 11, characterized by , that in the generation of the control signal (i M ) a signal representing the vehicle speed is received. [13] Electromechanical brake booster according to any one of claims 1 to 12, characterized by , that in the generation of the control signal (i M ) another factor (f3) is included, which can be adjusted by the driver to influence the characteristics of the pushrod return.

Images