Brake system control unit for a vehicle

Abstract

A brake system control unit for a vehicle having a hydraulic vehicle brake and electromechanical brake device comprises a microcontroller, a system ASIC and a brake motor ASIC, wherein the microcontroller is connected to the system ASIC and the brake motor ASIC via communication interfaces. In the brake motor ASIC, an interrogation signal sequence for interrogating the switched state of an actuation switch of the electromechanical brake device is generated.

Claims

1. A brake system control unit for a vehicle having a hydraulic vehicle brake and an electromechanical brake device including at least one electric brake motor, the brake system control unit comprising: a microcontroller configured to actuate at least one active brake component; a system ASIC configured to acquire sensor signals; and a brake motor ASIC configured to acquire sensor signals, the brake motor ASIC being configured to generate an interrogation signal sequence configured to interrogate a switched state of an actuation switch of the electromechanical brake device, wherein the actuation switch of the electromechanical brake device is configured to generate a response signal sequence as a function of the switched state and in reaction to the interrogation signal sequence, the response signal sequence being fed to the brake motor ASIC for evaluation, wherein the microcontroller is connected to the system ASIC and the brake motor ASIC via communication interfaces.

2. The brake motor control unit according to claim 1, wherein the system ASIC is configured to acquire wheel rotational speed signals.

3. The brake motor control unit according to claim 1, wherein the brake motor ASIC is configured to acquire wheel rotational speed signals.

4. The brake motor control unit according to claim 1, wherein the system ASIC and the brake motor ASIC are each configured to acquire pedal travel encoder signals of a brake pedal.

5. A method for operating a brake system control unit for a vehicle having a hydraulic vehicle brake and an electromechanical brake device including at least one electric brake motor, the brake system control unit including (i) a microcontroller configured to actuate at least one active brake component, (ii) a system ASIC configured to acquire sensor signals, and (iii) a brake motor ASIC configured to acquire sensor signals, the microcontroller is being connected to the system ASIC and the brake motor ASIC via communication interfaces, the method comprising: generating, with the brake motor ASIC, an interrogation signal sequence configured to interrogate a switched state of an actuation switch of the electromechanical brake device, the actuation switch of the electromechanical brake device being configured to generate a response signal sequence as a function of the switched state and in reaction to the interrogation signal sequence, the response signal sequence being fed to the brake motor ASIC for evaluation; and generating a braking force, in response to one of (i) a failure of the microcontroller, (ii) a failure of the system ASIC, and (iii) a failure of one of the communication interfaces, by actuating the electric brake motor as a function of the switched state of the actuation switch of the electromechanical brake device using the brake motor ASIC.

6. The method according to claim 5 further comprising: feeding, continuously and at cyclical intervals, the interrogation signal sequence to the actuation switch of the electromechanical brake device.

7. The method according to claim 5 further comprising: generating the braking force, in response to the one of (i) the failure of the microcontroller, (ii) the failure of the system ASIC, and (iii) the failure of one of the communication interfaces, by actuating the electric brake motor until a motor brake current of the electric brake motor reaches a defined maximum using the brake motor ASIC.

8. The method according to claim 5 further comprising: generating the braking force, in response to the one of (i) the failure of the microcontroller, (ii) the failure of the system ASIC, and (iii) the failure of one of the communication interfaces, by actuating the electric brake motor for a defined time period using the brake motor ASIC.

9. A brake system for a vehicle, the brake system comprising: a hydraulic vehicle brake; an electromechanical brake device including at least one electric brake motor and an actuation switch; and a brake system control unit configured to actuate adjustable brake system components of the brake system, the brake system control unit comprising: a microcontroller configured to actuate at least one active brake component; a system ASIC configured to acquire sensor signals; and a brake motor ASIC configured to acquire sensor signals, the brake motor ASIC being configured to generate an interrogation signal sequence configured to interrogate a switched state of the actuation switch of the electromechanical brake device, wherein the actuation switch of the electromechanical brake device is configured to generate a response signal sequence as a function of the switched state and in reaction to the interrogation signal sequence, the response signal sequence being fed to the brake motor ASIC for evaluation, wherein the microcontroller is connected to the system ASIC and the brake motor ASIC via communication interfaces.

10. The brake system according to claim 9, wherein the hydraulic vehicle brake includes an electrically controllable actuator configured to influence a hydraulic pressure.

11. The brake system according to claim 9, wherein wheel brake devices on a rear axle of the vehicle include the at least one electric brake motor.

12. The brake system according to claim 9, wherein the brake system is included in the vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further features and expedient embodiments can be found in the description of the figures and the drawings. In the drawings:

(2) FIG. 1 shows a schematic illustration of a hydraulic vehicle brake with a brake booster, wherein the wheel brake devices of the vehicle brake on the rear axle of the vehicle are additionally equipped with an electromechanical brake device with an electric brake motor,

(3) FIG. 2 shows a section through an electromechanical brake device with an electric brake motor, and

(4) FIG. 3 shows a functional diagram of a control unit of the brake system with a hydraulic vehicle brake and an electromechanical brake device.

DETAILED DESCRIPTION

(5) In the figures, identical components are provided with identical reference symbols.

(6) The hydraulic vehicle brake 1 illustrated in FIG. 1 for a vehicle comprises a front axle brake circuit 2 and a rear axle brake circuit 3 for supplying and actuating wheel brake devices 9 on each wheel of the vehicle with a brake fluid which is under hydraulic pressure. The brake circuits can also be embodied as two diagonal brake circuits, each with a front wheel and a rear wheel which is arranged diagonally with respect thereto.

(7) The two brake circuits 2, 3 are connected to a common master brake cylinder 4 which is supplied with a brake fluid via a brake fluid reservoir container 5. The master brake cylinder piston within the master brake cylinder 4 is actuated by the driver by means of the brake pedal 6, and the pedal travel which is exerted by the driver is measured by means of a pedal travel sensor 7. Between the brake pedal 6 and the master brake cylinder 4 there is a brake booster 10 which comprises, for example, an electric motor which preferably actuates the master brake cylinder 4 (iBooster) via a transmission. The brake booster 10 constitutes an active brake component for influencing the hydraulic brake pressure.

(8) The actuation movement of the brake pedal 6 which is measured by the pedal travel sensor 7 is communicated as a sensor signal to a control unit 11 of the brake system in which actuation signals for actuating the brake booster 10 are generated. The supply of the wheel brake devices 9 with brake fluid is carried out in each brake circuit 2, 3 by means of various switching valves which, together with further assemblies, are part of a brake hydraulic system 8. The brake hydraulic system 8 also includes a hydraulic pump which is a component of an electronic stability program (ESP). The hydraulic pump is also an active brake component for influencing the hydraulic brake pressure.

(9) FIG. 2 illustrates in detail the wheel brake device 9 which is arranged on a wheel on the rear axle of the vehicle. The wheel brake device 9 is part of the hydraulic vehicle brake 1 and is supplied with brake fluid 22 from the rear axle brake circuit. The wheel brake device 9 further has an electromechanical brake device which is preferably used in the stationary state as a parking brake for securing a vehicle, but can also be used during transport of the vehicle for braking the vehicle, in particular at relatively low vehicle speeds below a speed limiting value.

(10) The electromechanical brake device comprises a brake caliper 12 with a caliper 19 which engages over a brake disk 20. The brake device has, as an actuator element, a motor-transmission unit with a DC electric motor as a brake motor 13, the rotor shaft of which drives a spindle 14 in rotation, on which spindle 14 a spindle nut 15 is mounted in a rotationally fixed fashion. In the case of a rotation of the spindle 14, the spindle nut 15 is adjusted axially. The spindle nut 15 moves within a brake piston 16 which is a carrier of a brake lining 17 which is pressed against the brake disk 20 by the brake piston 16. On the opposite side of the brake disk 20 there is a further brake lining 18 which is fastened to the caliper 19 in a positionally fixed fashion. The brake piston 16 is sealed in a pressure-tight fashion with respect to the receiving housing on its outer side via a circumferential sealing ring 23.

(11) Within the brake piston 16, the spindle nut 15 can move axially forward in the direction of the brake disk 20 in the case of a rotational movement of the spindle 14 or axially rearward in the case of an opposing rotational movement of the spindle 14, until an end stop 21 is reached. In order to generate a clamping force, the spindle nut 15 acts on the inner end side of the brake piston 16 as a result of which the brake piston 16 which is mounted in an axially displaceable fashion in the brake device is pressed with the brake lining 17 against the facing end face of the brake disk 20. The spindle nut 15 constitutes a transmission element between the brake motor and the brake piston.

(12) For the hydraulic braking force, the hydraulic pressure of the brake fluid 22 from the hydraulic vehicle brake 1 acts on the brake piston 16. The hydraulic pressure can also be effective in a supporting fashion in the stationary state of the vehicle when the electromechanical brake device is actuated, with the result that the total braking force is composed of the portion which is provided by electric motor and the hydraulic portion. During the travel of the vehicle, either only the hydraulic vehicle brake is active or both the hydraulic vehicle brake and the electromechanical brake device or only the electromechanical brake device is active, in order to generate braking force. The actuation signals for actuating both the adjustable components of the hydraulic vehicle brake 1 and the electromechanical wheel brake device 9 are generated in the control unit 11.

(13) FIG. 3 illustrates a functional diagram of the control unit 11 which comprises a microcontroller 30, a system ASIC 31 and a brake motor ASIC 32. The microcontroller is connected to the system ASIC 31 via a communication interface SPI_1, and to the brake motor ASIC 32 via a further communication interface SPI_2.

(14) Wheel rotational speed signals which originate from wheel rotational speed sensors on two wheels of the vehicle can be received and conditioned in the system ASIC 31.

(15) Likewise, if appropriate motor rotational position signals from Hall sensors on the two electric brake motors of the electromechanical brake device can be received and processed in the system ASIC 31. The processed wheel rotational speed signals and the processed motor rotational position signals are made available to the microcontroller 30.

(16) The brake motor ASIC 32 communicates with the microcontroller 30 via the communication interface SPI_2. Further wheel rotational speed signals, which originate from wheel rotational speed sensors on other vehicle wheels, can received and processed in the brake motor ASIC 32. For example, the wheel rotational speed signals in the system ASIC 31 relate to the front wheels, and the wheel rotational speed signals in the brake motor ASIC relate to the rear wheels of the vehicle. The processed wheel rotational speed signals are made available to the microcontroller 30 by the brake motor ASIC 32.

(17) The brake motor ASIC 32 can further include, as electronic circuits, H bridges which are each assigned to an electric brake motor of the electromechanical brake device. The H bridges are actuated by means of the brake motor ASIC 32 and regulate the functions of the electric brake motors which, depending on the actuation, are applied in order to generate a braking force or opened or switched off in order to cancel a braking force.

(18) In the brake motor ASIC 32, an interrogation signal sequence 36 is generated regularly and at cyclical intervals, said interrogation signal sequence 36 being fed to the actuation switch 35 by means of which the electromechanical brake device with the electric brake motors is either switched on to generate a braking force in the application direction or switched on or switched off in order to release the breaking force. One of these current switched states of the actuation switch 35 can be interrogated by means of the interrogation signal sequence 36.

(19) For this, the interrogation signal sequence 36 is fed to the actuation switch 35 which, depending on the current switched state, generates as a response to the interrogation signal sequence 36 a response signal sequence 37 and sends this back to the brake motor ASIC. The response signal sequence 37 accordingly contains the information about the current switched state of the actuation switch 35. In the brake motor ASIC, the electric brake motor is then actuated, or if appropriate switched off, as a function of the switched state. The actuation or switching off of the electric brake motor takes place independently of the microcontroller 30, of the system ASIC 31, and one of the communication interfaces SPI_1 and SPI_2. It is therefore possible to actuate and switch off the electric brake motor even in the event of a failure of one of the abovementioned components in the control unit 11.