DE102012020421A1 - Brake system for highly automatic operable vehicle i.e. motor car, has brake circuits though which external power braking or internal power braking and auxiliary worker braking of vehicle are exclusively feasible - Google Patents

Abstract

The system (1) has open hydraulic brake circuits though which an external power braking or an internal power braking and an auxiliary worker braking of an electrical or hybrid vehicle are exclusively feasible. The external power braking is performed in normal operation of the vehicle such that predetermined brake force distribution on rotatable wheels (HL, HR, VL, VR) of the vehicle is more adjustable, where the braking force generated during the normal operation is higher than the braking force generated upon failure of external power braking in the brake circuit. An independent claim is also included for a method for generating braking force in a vehicle.

Description

The invention relates to a brake system of a vehicle, in particular a partially, highly or fully automatically operable vehicle, and a method for generating a braking force in such a vehicle.

The development of automatically operable vehicles may require an adaptation of the systems previously installed in conventional vehicles, in particular braking systems.

The DE 10 2011 078 118 A1 discloses a brake control system for a vehicle for manned and unmanned operation, wherein the brake control system comprises a hydraulic brake, a manually operated brake circuit connected to the hydraulic brake, and an electro-hydraulic brake circuit connected to the hydraulic brake. The electro-hydraulic brake circuit includes a pump, an inlet valve having an inlet connected to the pump, a first brake valve having an outlet connected to the hydraulic brake, and an inlet connected to an outlet of the inlet valve, a second brake valve having one with the hydraulic brake and an inlet connected to the outlet of the inlet valve, a first central unit operatively connected to the inlet valve and to the first brake valve, and a second central unit operatively connected to the inlet valve and to the second brake valve, the first and second exhaust ports the second central unit controls the intake valve and the first and second brake valves.

The DE 10 2008 041 760 A1 discloses a braking device for a motor vehicle having a first and a second group of brake circuits, wherein each brake circuit is associated with a group of wheels, at least the first group of brake circuits are formed as hydraulic brake circuits, wherein at least one group of wheels are connected to at least one operating unit that can cause a deceleration of the wheels. Furthermore, the braking device comprises a control device which controls the braking action of the brake circuit or groups of the second group and in particular the deceleration effect of the / of the impact units and wherein the first group of brake circuits can be controlled directly by the driver by means of a brake actuator. The document discloses a decoupling of hydraulic pumps in non-operated brake circuits.

The WO 2009/015973 A1 discloses an electric brake system for a motor vehicle having two brake circuits, each of the brake circuits comprising: at least one wheel brake actuator associated with a wheel of the motor vehicle and applying a braking force to the wheel, a wheel brake actuator control device associated with the wheel brake actuator and controlling the wheel brake actuator; a central control unit communicatively connected to the wheel brake actuator control unit and adjusting the braking force exerted by the at least one wheel brake actuator, and a brake circuit power supply for supplying power to the wheel brake actuator control unit and the central control unit of this brake circuit, the brake circuit power supply comprising: a battery the Radbremsaktor control unit and / or the central control unit of the associated brake circuit supplied at least after a failure of a base vehicle electrical system of the vehicle with voltage, and at least one DC / DC converter with which the Bat terie is coupled to the base board network. In this case, each brake circuit is further assigned a brake light, which can be activated by the respective central control unit upon activation of the brake light switch via a line.

In existing vehicles, brake devices are oversized from rear wheels of the vehicle. This affects z. B. positive to a braking of teams, in which the rear wheels of the towing vehicle are additionally burdened by a dynamic axle load displacement of the trailer. In individual vehicles, however, the rear wheels can block with increasing delay in front of the front wheels of the vehicle at such an oversizing, which can lead to the risk of skidding. Such a risk of skidding is reduced or eliminated by an electronic brake force distribution. This z. B. Hydraulic pressure in hydraulic brakes of the rear wheels reduced. Thus, in a normal operation of the vehicle, an electronically controlled brake pressure reduction takes place, ie a reduction of a braking force on the rear wheels. The disadvantage here is that in case of failure of the electronic brake force distribution, z. B. in case of failure of the power supply, the rear wheels still block first. For an at least partially automatically operated vehicle, this is particularly critical, as in the case of failure of the power supply, the previously explained danger of skidding exists.

It therefore raises the technical problem, a brake system of a vehicle, in particular a partially, highly or fully automatically operable vehicle, and to provide a method for generating a braking force in such a vehicle, which in case of failure, especially in case of failure of an electronic brake force distribution, enable safe operation of the vehicle.

Proposed is a brake system of a vehicle. In particular, a braking system of a partially, highly or fully automatically operable vehicle is proposed.

The term semi-automatic, highly automatic or fully automatic describe different degrees of automation of a vehicle guidance. In addition to these degrees of automation z. B. still the degrees of automation "Driver only" and "Assisted" exist. In a highly automated vehicle can z. B. a transverse and longitudinal guidance of the vehicle by an automation system of the vehicle, wherein a driver does not need to monitor the automation system and the vehicle management permanently. For example, in a fully automatic vehicle, the automation system takes over a lateral and longitudinal guidance completely in a defined application. In this case, the driver no longer has to monitor the automation system and the vehicle guidance. In a "driver only" powered vehicle, the driver permanently performs the longitudinal and transverse guidance. In an assisted-powered vehicle, the driver permanently performs either the lateral or longitudinal guidance. The respective other driving task is carried out within certain limits of the automation system, the driver must monitor the automation system and the vehicle management permanently. In a partially automated-operated vehicle, the automation system can take over the lateral and longitudinal guidance, whereby the driver must permanently monitor the automation system and the vehicle management.

The brake system comprises a first brake circuit and at least one further brake circuit. A brake circuit may in this case designate an association of means for generating, transmitting and controlling a braking force acting on one or more wheels.

Further, by at least the first brake circuit exclusively, so in any mode of operation of the vehicle, a Fremdkraftbremsung the vehicle feasible. A Fremdkraftbremsung refers to a braking of the vehicle, during which a braking force or a brake pressure exclusively by an actuator, for. As a pump or an electric motor is generated. In this case, the energy required to generate the braking force is thus supplied by one or more energy supply devices, with the exception of the physical force of the vehicle driver.

Alternatively, by at least the first brake circuit both a power brake and an auxiliary braking of the vehicle can be carried out. An auxiliary braking means in this case a braking, in which the energy required to generate the braking force of the physical force of the driver and one or more energy supply devices starts or is supplied. Thus, the at least one brake circuit can be operated bimodal. So z. B. in a first mode, a power brake and in a different mode of operation of this mode, an auxiliary power braking are performed.

The brake circuits here may be hydraulic brake circuits. However, it is also possible that only a part of the brake circuits are designed as hydraulic brake circuits. The first brake circuit, by which the external power braking is feasible, this may preferably be a the rear wheels of the vehicle associated brake circuit.

Due to the dual-circuit advantageously results in a redundancy with respect to a generation of the braking effect, since in case of failure of a brake circuit in the case of a single fault at least the remaining brake circuit is still able to generate a braking force.

According to the invention, in a normal operation of the vehicle, the external power braking can be carried out in such a way that a predetermined braking force distribution on rotatable wheels of the vehicle can be set. Here, in the brake circuit / the brake circuits that do not perform power braking, a power brake or muscle braking are performed. The braking force distribution here refers to a distribution of the total braking force generated on the individual wheels, in particular the front and rear wheels of the vehicle. Also, the braking force distribution may refer to a distribution of the total generated braking force on the rotatable wheels of a front axle (front wheels) and the rotatable wheels of a rear axle (rear wheels). For example, the predetermined braking force distribution can be distributed to 2/3 on the front wheels and 1/3 on the rear wheels. The predetermined braking force distribution in normal operation can result in particular as a function of vehicle characteristics, in particular a position of a center of gravity, an empty weight and other physical vehicle characteristics.

The set by the Fremdkraftbremsung braking effect can in this case in normal operation in dependence of all other generated braking forces, eg. B. the braking forces generated by the remaining brake circuits are adjusted so that the predetermined braking force distribution results.

The normal operation of the vehicle in this case denotes an operation in error-free case, wherein there is no error in any of the brake circuits. Also, the normal operation can indicate a fault-free operation of the vehicle, wherein the vehicle is simultaneously operated partially, fully or fully automatically.

The proposed brake system advantageously allows the adjustment of the braking force distribution in normal operation such that blocking of the rear wheels is prevented in time before the front wheels, whereby a risk of skidding when braking is reduced or eliminated. The predetermined braking force distribution is in this case selected such that z. B. up to a first predetermined braking delay, the rear wheels of the vehicle do not block in time before the front wheels.

In particular, the vehicle may be an electric or hybrid vehicle. In this case, in a recuperation operation of the electric or hybrid vehicle, an additional braking force can be generated by the electric machine operated in a generator mode. In this case, the external power braking depending on the braking effect Rekuperationsmoments and depending on the other, z. B. in the remaining brake circuits, braking forces generated are adjusted so that the predetermined braking force distribution is achieved.

In a further embodiment, the braking system is designed such that in the event of failure of the external power braking by the first brake circuit, a braking force can be generated such that a further predetermined braking force distribution, which is different from the first predetermined braking force distribution, is adjustable. This operation can also be referred to as fault operation of the first brake circuit. A failure of the external power braking, for example, by a failure of a power supply of means for generating the external power, in particular a power supply of the aforementioned actuator, take place. However, a failure of the power brake also in other cases, eg. B. in case of a defect of the actuator or in case of failure of a controller of the actuator, done. In this case, a braking force can still be generated by the first brake circuit, for example by an auxiliary power brake or a muscle power brake or by emergency power brakes.

Further, the braking force generated by the Fremdkraftbremsung in normal operation during a braking operation is higher than a braking force generated in case of failure of the Fremdkraftbremsung in the first brake circuit at a similar braking process. Thus, an additional braking force is generated by the power brake, the braking force in the first brake circuit without the power brake, z. B. in case of failure of the power brake, would be increased and not, as in the prior art, reduced. In error mode, there is thus a relapse to the further predetermined braking force distribution, wherein the first brake circuit in the first brake circuit, a braking effect is generated which is less than the braking effect at a similar braking in normal operation. This can for example be chosen such that rear wheels, for example, at delays that are greater than another predetermined delay, z. B. at delays greater than 0.8 g, block in time before the front wheels. The further predetermined delay may in this case be greater than the previously explained first predetermined delay.

This results in an advantageous manner that braking devices of the brake system, in particular brake devices of rear wheels, can be dimensioned smaller in error operation with respect to a maximum to be generated braking effect, resulting in particular cost savings and a smaller space requirement. In error mode, a safe operation of the vehicle is made possible by the further predetermined braking force distribution.

Also results in an advantageous manner that weight is saved with a smaller dimensioning of braking devices, whereby fuel consumption or energy consumption of the vehicle can be reduced.

In a further embodiment, the first brake circuit is a hydraulic brake circuit, wherein the first brake circuit is an open brake circuit. An open hydraulic brake circuit in this case denotes a brake circuit, which is fluidly connected or connected to a reservoir for a brake fluid. For example, the open brake circuit can be fluidly connected or connectable on the input side to a master brake cylinder and can be connected or connected on the output side to the compensation reservoir. The hydraulic brake circuit can in this case comprise a pumping device or pump, wherein by means of the pumping device brake fluid from the reservoir can be sucked in order to effect a pressure increase and thus a braking force increase in the open brake circuit. Of course, by means of the pumping device also brake fluid can be pumped from the open brake circuit in the surge tank to reduce a pressure in the open brake circuit and thus a braking force. The pumping device, which is an example of a pressure generating device, thus serves to adjust the z. B. the power brake braking force generated.

The remaining brake circuits can also be hydraulic brake circuits, these as closed brake circuits or also as open brake circuits can be executed. A closed brake circuit in this case denotes a brake circuit, which has no fluid connection to the expansion tank. In particular, the closed brake circuit on the input and output side can be fluidly connected or connectable to the master brake cylinder.

The use of a hydraulically open brake circuit advantageously results in the simplest possible generation of a braking force in the context of an external power brake. The braking force generated in the open brake circuit can be variably adjustable, whereby z. B. also the previously explained recuperation torque in electric or hybrid vehicles when braking can be considered.

If the first brake circuit is hydraulically connected to the master brake cylinder, then, in particular in the case of an electric or hybrid vehicle, it is further advantageous for a pedal simulator, i. H. a device for generating a counter pedal force can be saved. The device for generating a counter pedal force here generates an operating pressure of a driver on a brake pedal counteracting pressure through which the driver haptically a strength of the set by him pedal action braking is mediated. If the first brake circuit is hydraulically connected to the master brake cylinder, a haptic feedback can be generated to the vehicle driver by a corresponding pressure build-up in the first brake circuit during the recuperation operation simultaneously via the master brake cylinder. As a result, the function of the pedal simulator is thus taken over by the first brake circuit.

In a preferred embodiment, the open brake circuit can be fluidly separated by a valve from a master brake cylinder. In this way, a fluidic connection between the open brake circuit and the master cylinder can be separated in an advantageous manner and thus a haptic feedback of a set in the open brake circuit braking force to a driver can be prevented. Is the open brake circuit z. B. at a closed valve fluidly separated from the master cylinder, so in the open brake circuit, a braking force can be generated without haptic feedback to a driver occurs. Thus, the open brake circuit with closed valve perform only a power brake. In an open state of the valve, the open brake circuit can perform both a power brake and an auxiliary power brake. This advantageously increases possible uses of the open brake circuit.

In a further embodiment, the open brake circuit is associated with the rear wheels. By the open brake circuit, in this case, therefore, the first brake circuit, so acting on the rear wheels of the vehicle braking force can be generated. Thus, in an advantageous manner, the braking force acting on the rear wheels can be varied, whereby in a particularly simple manner, a blocking of the rear wheels can be prevented in time before the front wheels.

In a further embodiment, the brake system comprises two further hydraulic brake circuits, which are each assigned to a front wheel. Thus, there are three hydraulic brake circuits in the brake system. The master cylinder can be a triple master cylinder here. In this case, no higher delay in leakage of a brake circuit can be achieved, in particular in case of leakage in one of the brake circuits associated with the front wheels. It is also possible that the brake system comprises a further hydraulic brake circuit, which is assigned to two front wheels. Thus, two hydraulic brake circuits are present in the brake system. The master cylinder can be a tandem master cylinder here.

The brake circuit (s) associated with the front wheels may in this case be open or closed brake circuits. Are in the / the brake circuit / s elements of a slip control system, in particular a pumping device of a slip control system arranged, it follows in an advantageous manner that in case of failure of the slip control system continue all rear and front wheels or at least all front wheels, z. B. can be braked by a muscle power brakes.

In a further embodiment, the brake system comprises a drive device for a first and a further pump device. The first pumping device is in this case associated with a first hydraulic brake circuit, for example the previously mentioned open brake circuit, and the further pumping device is associated with a further hydraulic brake circuit. The pumping devices can be operated simultaneously by the drive device.

For example, an output shaft of the drive device, which may be designed, for example, as a servomotor, can be mechanically connected to both an input shaft of the first pump device and an input shaft of the further pump device. Further, a connecting device is arranged between the drive device and the further pumping device, for example in a mechanical transmission path, wherein by means of the connecting device a frictional connection between the drive device and the further pumping device can be separated and produced is. The drive device and the pumping devices can be components of a slip control system of the brake system. The connecting device may in this case be, for example, a separable clutch or a freewheel device, wherein the freewheel device produces a frictional connection between the drive device and the further pump device when the output shaft of the drive device is rotated in a first direction of rotation and reverses a frictional connection when the output shaft in one of the first rotational direction opposite direction of rotation is rotated.

This results in an advantageous manner that the frictional connection between the drive device and the other pumping device can be separated when a foreign power braking is performed by the first brake circuit, wherein the braking force generated during the Fremdkraftbremsung generated by operation of the first pumping device. As a result, an independence of the setting of braking forces in the different hydraulic brake circuits is increased in an advantageous manner.

In a further embodiment, at least one of the brake circuits comprises at least one electromechanical brake device. The brake circuit may in this case be, in particular, the first brake circuit, wherein the external power braking takes place through the first brake circuit, as explained above. Here, the first brake circuit, an electromechanical brake circuit, wherein the electromechanical brake circuit comprises only means for generating, transmitting and adjusting an electromechanically generated braking force. By such a trained first brake circuit only a power brake can be performed.

This results in an advantageous manner a dynamic and easy to be generated adjustment of the braking force generated by the power brake and thus a simple adjustment of the first predetermined braking force distribution.

In a further embodiment, the brake system comprises a first and at least one further brake light. Furthermore, the brake system comprises a first control device and at least one further control device, wherein the first brake light can be controlled exclusively by means of or via the first control device and the at least one further brake light can be controlled exclusively by means of or via the further control device. The control units can in this case be connected to each other in terms of data or signal technology, for example via a bus system, eg. B. a CAN bus.

In this case, a power driver for generating an electric power for operating the brake light can be integrated into the corresponding control unit. The control units can, in particular in the event of a fault, generate the control signals required to control the respective brake lights themselves. In a normal mode, i. H. In a fault-free operation, the control signals for controlling all the brake lights from a control unit, such as the first control unit, are generated, wherein the control signals for the at least one additional brake light from the first control unit to the further control unit are transmitted and this then controls the further brake light. As a result, the further brake light is controlled by the first control device via the further control device.

This results in an advantageous manner that in case of failure, at least one brake light of the vehicle is operable. In particular, the first control unit can be assigned to a first electrical brake circuit and the further control unit to a further electrical brake circuit. This will be explained in more detail below.

Further proposed is a method for generating a braking force in a vehicle, in particular in a partially, fully or fully automatically operable vehicle. In this case, a braking force is generated in each case by a first brake circuit and by at least one further brake circuit of a brake system of the vehicle. During operation of the vehicle, an external power braking or auxiliary power braking of the vehicle is performed by the first brake circuit. In this case, only an external power braking can be performed during operation of the vehicle.

According to the invention, in a normal operation of the vehicle, the external power braking or power brake is performed such that a first predetermined braking force distribution is set on rotatable wheels of the vehicle. In this case, the braking force generated by or during the external power braking is thus adjusted by the first brake circuit so that the first predetermined braking force distribution is set on the rotatable wheels of the vehicle. In the context of a power brake, the braking effect generated independently of the physical force of the driver can be adjusted here.

The proposed method advantageously makes it possible to set a brake-force distribution in normal operation in such a way that locking of the rear wheels in time ahead of the front wheels can be prevented. In particular, this can be generated in the normal operation of the vehicle, an additional braking force, so that in normal operation by the first brake circuit generated braking force is higher than a braking force generated by the first brake circuit in error operation, wherein an error operation z. B. called an operation in case of failure of the power brake. In error operation, a further predetermined braking force distribution is set here, which is different from the first predetermined braking force distribution.

The invention will be explained in more detail with reference to several embodiments. The figures show:

1 FIG. 2 is a schematic block diagram of a brake system in a first embodiment; FIG.

2 a schematic block diagram of a brake system in a second embodiment,

3 FIG. 2 is a schematic block diagram of a brake system in a third embodiment; FIG.

4 FIG. 2 is a schematic block diagram of a brake system in a fourth embodiment; FIG.

5 FIG. 2 is a schematic block diagram of a brake system in a fifth embodiment; FIG.

6 FIG. 2 is a schematic block diagram of a brake system in a sixth embodiment; FIG.

7a a cross section through an eccentric pump assembly,

7b a cross section through a further eccentric pump arrangement,

8th a schematic block diagram of a brake system in a seventh embodiment and

9 a schematic block diagram of a brake system in an eighth embodiment.

Hereinafter, like reference numerals designate elements having the same or similar technical features.

In 1 is a schematic block diagram of a brake system according to the invention 1 shown in a first embodiment. The brake system 1 includes a first hydraulic brake circuit and a second hydraulic brake circuit. Next includes the brake system 1 an arrangement 2 of brake lines 3 holding a master cylinder 4 fluidly connect with wheel brake cylinders, not shown, a right front wheel VR, a left front wheel VL, a right rear wheel HR and a left rear wheel HL. Next includes the brake system 1 a surge tank 5 for brake fluid and a level sensor 6 for detecting a level of the brake fluid in the expansion tank 5 , Next includes the brake system 1 an electric brake booster 7 and a rotor angle sensor 8th for detecting a rotor angle of a motor, not shown, of the electric brake booster 7 , The brake system 1 also includes a brake pedal 9 and a force sensor 10 for detecting a vehicle driver, not shown, on the brake pedal 9 applied pedal force F _brake . Next includes the brake system 1 in the arrangement 2 electromechanical valves 11 , Here it is shown that to some of the electromechanical valves 11 one check valve each 12 fluidly connected in parallel and also in outlet lines of a first pump P1 and a second pump P2 such check valves 12 are arranged. Next includes the brake system 1 in the arrangement 2 a pressure sensor 13 for detecting a brake pressure in the second hydraulic brake circuit. Next includes the brake system 1 in the second hydraulic brake circuit a low-pressure accumulator 14 , Also shown are wheel speed sensors 15 for detecting a rotational speed of the rotatable wheels VR, HL, VL, HR. For the sake of simplicity, sensors are summarized 16 for recording driving dynamics variables, eg. B. for detecting a yaw angle, a lateral acceleration and a steering angle.

Next includes the brake system 1 the first pump P1 and the second pump P2, which are driven in common by a servo motor M. The servomotor M is here a servomotor with adjustable speed. The first pump P1 is fluidly arranged in the first hydraulic brake circuit, that is in a part of the arrangement 2 that the master cylinder 4 connects with the wheel brake cylinders of the rear wheels HR, HL. By means of the first pump P1, a pressure in this part of the arrangement 2 to be changed. The second pump P2 is in the second hydraulic brake circuit, that is in a part of the arrangement 2 holding the master cylinder 4 with the wheel brake cylinders of the front wheels VL, VR fluidly connects. In this case, a pressure in the second hydraulic brake circuit can be changed by means of the second pump P2. The pumps P1, P2 and the servo motor M in this case form elements of a slip control system.

The brake system 1 further includes a pressure sensor 22 which is arranged in the first hydraulic brake circuit. The first hydraulic brake circuit refers to the part of the arrangement 2 that the master cylinder 4 Fluidtechnisch with the wheel brake cylinders of the rear wheels HL, HR and with the expansion tank 5 combines. This first hydraulic brake circuit is an open brake circuit, as it has the input side with the Master Cylinder 4 and on the output side with the expansion tank 5 fluidly connected or connectable. Next is the first hydraulic brake circuit through a valve 11a from the master cylinder 4 fluid-technically separable. By operation of the first pump P1, external power braking of the rear wheels HL, HR can be performed by the first hydraulic brake circuit. Is the valve 11a closed, there is no haptic feedback of the braking force set in this way on the brake pedal 9 and thus to a driver. The second hydraulic brake circuit comprises the part of the arrangement 2 that the master cylinder 4 with wheel brake cylinders of the front wheels VL, VR fluidly connects.

A first electrical brake circuit of the brake system 1 comprises a first control and evaluation device 17 and a first battery 18 , where the first battery 18 an example of a first energy source. A second electrical brake circuit of the brake system 1 comprises a second control and evaluation device 19 and a second battery 20 , where the second battery 20 an example of a second source of energy. An electric brake circuit in this case denotes a signal and energy-related composite of elements of the brake system 1 wherein the elements may be associated with the first hydraulic and / or the second hydraulic brake circuit. An electrical brake circuit can, for. B. elements for generating, distributing and controlling a braking force, which require electrical energy for operation. These elements of the first electric brake circuit can be used both for generating a braking force in the first hydraulic brake circuit and in the second hydraulic brake circuit.

The first control and evaluation device 17 is via a CAN bus 21 with the second control and evaluation device 19 connected. Also are the sensors 16 over the CAN bus 21 with the control and evaluation devices 17 . 19 connected. Here are the sensors 16 Sensors that are associated with both the first and the second electrical brake circuit. The rotor angle sensor 8th and the force sensor 10 represent sensors that are associated with the first electrical brake circuit. Here, the rotor angle sensor 8th and the force sensor 10 through the first battery 18 be supplied with electrical energy. The level sensor 6 can z. B. connected directly to a display in the instrument cluster.

The second electric brake circuit comprises the second control and evaluation device 19 , the second battery 20 , the servo motor M, the first and second pumps P1, P2, valves 11 , the wheel speed sensors 15 and the pressure sensor 13 , Here are these elements from the second battery 20 supplied with electrical energy. In contrast, the first electrical brake circuit comprises the first control and evaluation device 17 , the first battery 18 , the electric brake booster 7 with the master cylinder 4 and, as previously mentioned, the rotor angle sensor 8th and the force sensor 10 , These items are from the first battery 18 supplied with electrical energy.

The electric brake booster 7 with the master cylinder 4 forms a first pressure generating device of the first electric brake circuit. Through the electric brake booster 7 a pressure in both the first and in the second hydraulic brake circuit can be adjusted when the valve 11a is open. The second electric brake circuit includes a second pressure generating device formed by the servo motor M and the pumps P1, P2. By operation of the servomotor M, a pressure can be adjusted both in the first and in the second hydraulic brake circuit.

In this case, the first pressure-generating device can be supplied from the first energy source, wherein the further pressure-generating device can be supplied from the further energy source. Furthermore, a single fault can be detectable in the first or the second electrical brake circuit. Next, a faulty electrical brake circuit can be deactivated and a functional electric brake circuit can be activated. Furthermore, a braking force which can be generated by means of the first pressure generating device is greater than or equal to a predetermined service braking effect, wherein a braking force which can be generated by means of the further pressure generating device is greater than or equal to the predetermined service braking effect. The service brake effect, for example, in the scheme ECE R13H be defined.

In 2 is a schematic block diagram of a second embodiment of a brake system 1 shown. In contrast to 1 includes the in 2 illustrated brake system 1 a first hydraulic brake circuit connecting the expansion tank 5 Fluidtechnisch with Radbremszylindern the rear wheels HL, HR connects. In this case, there is no fluidic connection of the first hydraulic brake circuit to the master brake cylinder 4 , Further, the brake system comprises a second hydraulic brake circuit, the master cylinder 4 fluidly connected to a wheel brake cylinder of the left front wheel VL. Next includes the brake system 1 a third hydraulic brake circuit, the master cylinder 4 fluidly connected to a wheel brake cylinder of the right front wheel VR. Here, the brake system includes 1 in addition to the first pump P1 and the servo motor M, a second pump P2 and a third pump P3. The second pump P2 is hereby arranged in the second hydraulic brake circuit and the third pump P3 in the third hydraulic brake circuit. The pumps P1, P2, P3 and the servo motor M in turn form a slip control system. In the in 2 illustrated brake system 1 the rear wheels HL, HR are operated in all operating states as a power brake. Thus, only a foreign power braking is feasible by the first hydraulic brake circuit. The pumps P1, P2, P3 are mechanically connected to an output shaft of the servomotor M so that the servomotor M can simultaneously drive all three pumps P1, P2, P3. In case of failure of the slip control system can in the in 2 brake system shown only the front wheels VL, VR are hydraulically braked. However, it is advantageous that by three brake circuits, a higher delay in case of leakage in one of the brake circuits is possible.

This in 2 illustrated brake system 1 can with respect to the electric brake circuits in the same way as in 1 illustrated brake system 1 be formed, wherein the second electric brake circuit is additionally associated with the third pump P3.

In 3 is a braking system 1 shown in a third embodiment. In contrast to 2 is the master cylinder 4 designed as a so-called triple master cylinder with three separate fluid circuits. A first hydraulic brake circuit connects the master cylinder 4 Fluidtechnisch with Radbremszylindern the rear wheels HL, HR and with the expansion tank 5 , A second hydraulic brake circuit connects a wheel brake cylinder of the left front wheel VL to the master cylinder 4 , A third hydraulic brake circuit connects the master cylinder 4 with a wheel brake cylinder of the right front wheel VR. Here again, the first hydraulic brake circuit is an open circuit. Advantageously, this results in that in case of failure of a slip control system which is formed by a first pump P1, a second pump P2, a third pump P3 and a servo motor M, all four wheels HL, HR, VL, VR can be braked. In the event of a leakage in one of the hydraulic brake circuits, a high residual braking effect, in particular a service braking effect, which, for example, can be achieved. B. in the scheme ECE R13H is defined. In normal operation, an external power braking can be performed by the first hydraulic brake circuit such that a first predetermined braking force distribution at the wheels HL, HR, VL, VR is achieved.

This in 3 illustrated brake system 1 can with respect to the electric brake circuits in the same way as in 2 illustrated brake system 1 be educated.

In 4 is a braking system 1 shown in a fourth embodiment. Unlike the in 3 illustrated brake system 1 In this case, all three hydraulic brake circuits open brake circuits, in particular, the second and the third hydraulic brake circuit is fluidly with both the master cylinder 4 , which is also designed as a triple master cylinder, and with the expansion tank 5 connected. This results in an advantageous manner that a brake force distribution between front and rear wheels HL, HR, VL, VR can be set even more variable.

This in 4 illustrated brake system 1 can with respect to the electric brake circuits in the same way as in 2 illustrated brake system 1 be educated.

It is further conceivable that the braking system 1 in all of the 1 to 4 illustrated embodiments comprises at least one electromechanical parking brake, the z. B. a rear wheel HR, HL is assigned. Also, this electromechanical parking brake can be operated in a normal operation of the vehicle such that the first predetermined braking force distribution is set.

In 5 is a braking system 1 shown in a fifth embodiment. Here, the brake system includes 1 three brake circuits. Unlike the in 1 to 4 illustrated brake systems 1 a first brake circuit is designed as an electromechanical brake circuit. By the first electromechanical brake circuit in this case a braking force by electromechanical brake devices (not shown) can be generated, which acts on the rear wheels HL, HR of the vehicle. A second brake circuit is a hydraulic brake circuit and connects a master cylinder 4 with a wheel brake cylinder of a left front wheel VL. A third brake circuit is also a hydraulic brake circuit and connects the master cylinder 4 with a wheel brake cylinder of a right front wheel VR of the vehicle. The second and the third hydraulic brake circuit are hereby closed brake circuits.

In 5 is shown that the electromechanical braking devices of the rear wheels HL, HR data or signal technology with a first control unit 17 connected, wherein control signals via a data line 27 , z. A bus, from the first controller 17 can be transmitted to the electromechanical braking devices. Electrical energy for supplying the electromechanical braking devices may be from a first battery 18 via a supply line 23 be transmitted to the electromechanical braking devices.

Likewise, the electromechanical brake devices are data or signal technology with a second control unit 19 connected, with control signals via data lines 24 can be transmitted to the electromechanical braking devices. The brake system 1 can also have an angle sensor 25 comprising a rotation angle of a brake pedal 9 detected and corresponding output signals via data lines 26 transmits to the electromechanical braking devices.

A vehicle driver or an automation system for partially, fully or fully automatic driving in this case can generate a brake command from the first control unit 17 is processed. The electric brake booster 7 is through the first controller 17 controlled and causes a hydraulic braking of the front wheels VL, VR. From the first controller 17 can the brake request to the second control unit 19 via a CAN bus 21 be transferred, wherein in the second control device 19 a brake force distribution is calculated and generates control signals for the electromechanical braking devices and the data lines depending on the calculated brake force distribution 24 that z. B. bus lines of a CAN or Flexray bus may be transmitted to the electromechanical braking devices. These are so by control signals of the second control unit 19 controlled accordingly. The controllers 17 . 19 can setpoints for the electromechanical braking devices via the CAN bus 21 compare. Optionally, the CAN bus 21 and the z. B. trained as a bus data line 27 , the data controller, the first control unit with the electromechanical brakes data or technically connects, be merged.

In a faultless brake system 1 For example, a vehicle operator may initiate vehicle braking by depressing the brake pedal or an automation system. In this case, the electronic brake booster 7 over the master cylinder 4 generate a braking force in the second and third hydraulic brake circuits, whereby only the front wheels VL, VR are braked. The brake request is made via the CAN bus 21 from the first controller 17 to the second controller 19 transfer. The second control unit 19 performs a monitoring of the wheels HR, HL, VR, VL blocking and compliance with a driving stability. At the same time, the second control unit 19 over the two parallel data lines 24 activate the electromechanical braking devices of the rear wheels HL, HR according to a desired brake force distribution.

In case of failure of the electronic brake booster 7 or the first controller 17 Can a driver over the master cylinder 4 unreinforced build or generate a braking force, this being a pressure sensor 13 is detected. In this case, the second control unit 19 act as a hydraulic brake booster and the servo motor M and the valves 11 such that a predetermined braking force is generated on the two front wheels VL, VR. The electromechanical braking devices of the rear wheels HR, HL are then from the second controller 19 driven. Thus, a braking force build-up takes place on all four wheels HR, HL, VR, VL.

This in 5 illustrated brake system 1 can with respect to the electric brake circuits in the same way as in 1 illustrated brake system 1 be formed, wherein the electromechanical brake devices are associated with the first electrical brake circuit.

In a single error in the first electric brake circuit, z. B. in case of failure of the first battery 18 , the first controller 17 , the electromechanical brake device of the right rear wheel HR, the electromechanical brake device of the left rear wheel HL and / or the electric brake booster 7 A driver can use the master cylinder 4 unreinforced build a braking force, which, as previously explained, from the pressure sensor 13 is detected. Again, the second controller acts 19 as a hydraulic brake booster and controls the pumps P2, P3, which are arranged in the second and the third hydraulic brake circuit, via the servo motor M and the valves 11 such that a desired braking force is generated on the two front wheels VL, VR. A brake force buildup is thus exclusively on the front wheels VR, VL.

In case of failure of an electromechanical braking device is a deceleration, wherein the electric brake booster 7 hydraulically generated at the two front wheels VL, VR braking force and the second control unit 19 on the remaining, intact electromechanical brake via the corresponding bus line 24 requests a braking force generation.

In a single error in the second electrical brake circuit, z. B. in case of failure of the second control unit 19 , can from the first controller 17 controlled electric brake booster 7 build a hydraulic braking force on the two front wheels VL, VR. The electromechanical braking devices can in this case a braking request via the data line 27 from the first controller 17 or via data lines 26 that the angle sensor 25 connect with the electromechanical brakes data technology, received. A height of the braking force generated by the electromechanical brake devices can be selected according to a fixed braking force distribution. As a result, a deceleration with a fixed brake force distribution on all four wheels HL, HR, VL, VR can be performed.

The same procedure is feasible if the second battery 20 , the servomotor M, the second pump P2, the third pump P3, one or more valves 11 and / or the pressure sensor 13 fails.

In the event of a leakage in the second or third brake circuit, hydraulic braking can take place through the intact hydraulic brake circuit and through the two electromechanical brakes of the rear wheels HL, HR. In this case, a braking force build-up takes place on three wheels. In all scenarios explained above, a service braking effect, e.g. B. one in the scheme ECE R13H defined service braking effect, be satisfied.

In 6 is a schematic block diagram of a brake system 1 in a sixth embodiment. This in 6 illustrated brake system 1 includes three hydraulic brake circuits. A first hydraulic brake circuit is a hydraulically open brake circuit that includes a surge tank 5 fluidly connects with wheel brake cylinders of rear wheels HL, HR of the vehicle. In the first hydraulic brake circuit, a two-piston pump is arranged, which is represented by a first pump P1 and a further pump P4, which are driven together by a variable-speed servomotor M. The second hydraulic brake circuit connects a master cylinder 4 Fluidtechnisch with a wheel brake cylinder of a left front wheel VL. A third hydraulic brake circuit connects the master cylinder 4 Fluidtechnisch with a wheel brake cylinder of the right front wheel VR, wherein the second and the third brake circuit are hydraulically closed brake circuits. Here, in the second hydraulic brake circuit, a second pump P2 and in the third hydraulic brake circuit, a third pump P3 is arranged.

The pumps P1, P2, P3, P4 and the servo motor M form a slip control system. Conventional slip control systems usually use 2-piston pumps or 6-piston pumps. If there are two brake circuits, one or three small pumps can be installed per brake circuit. Three small pumps lead to a more even pressure build-up than a large pump. It can z. B. eccentric pumps are used, wherein a rotating eccentric drives the corresponding pump elements.

Since the rear wheels HR, HL are braked during each deceleration by means of an external power braking, preferably the previously described multi-piston pump is to be installed here. The first pump P1 and the further pump P4 serve in this case a pressure build-up in the first hydraulic brake circuit, which can perform only a foreign power braking. In the first hydraulic brake circuit but also another multi-piston pump can be arranged.

The second pump P2 and the third pump P3 can preferably be designed as a single-piston pump. The second and the third pump P2, P3 are needed only with an active slip control. Since such a slip control is activated only in certain, rarely occurring driving situations, a cost-effective single-piston pump for controlling the braking force in the second and the third hydraulic brake circuit is sufficient.

In the in 6 illustrated brake system 1 It is shown that the first pump P1 and the other pump P4 are mechanically fixed, ie inseparable, coupled to the servo motor M. This z. B. an output shaft AA (see 7a ) of the servomotor M be fixedly coupled to input shafts of the pumps P1, P4. The second pump P2 and the third pump P3 is in this case via an electrically controllable coupling 28 , z. As a magnetic powder clutch, connected to the servo motor M. Thus, a frictional connection between the servo motor M and the second and the third pump P2, P3 can be separated. In normal operation, this can be the clutch 28 be controlled so that the servo motor M is mechanically separated from the pumps P2, P3, the clutch 28 so it is open. Since, in normal operation, the first hydraulic brake circuit can exclusively perform a power-brake application, the servomotor M must drive the first and the further pumps P1, P4 during each braking operation. In a fixed coupling of the servomotor with the second and third pump P2, P3 in this case, the second and third pump P2, P3 would be operated, whereby a braking force in the second and in the third hydraulic brake circuit is changed. This change would have to be compensated by a complex control. Thus, in 6 illustrated brake system 1 in an advantageous manner, that during normal operation, only the pumps P1, P4 arranged in the first hydraulic brake circuit are operated during deceleration.

Instead of a clutch 28 can also be used a freewheel device. This can, for. B. in a first direction of rotation, z. B. the output shaft of the servomotor M, automatically engage and thus establish a frictional connection between the servo motor M and the pumps P2, P3, while the freewheel device automatically opens in a direction opposite to the first direction of rotation. This can advantageously be dispensed with an expensive electronic clutch together with their control. Should be in this case z. B. only a pressure build-up in the first hydraulic brake circuit are generated, then a direction of rotation of the servo motor, in particular the output shaft of the servo motor M, are chosen such that the freewheel device opens. However, if a slip control on the front wheels VL, VR required so the servo motor M can be controlled such that a direction of rotation of the servo motor M, in particular the output shaft of the servo motor M, adjusts, in which the freewheel device a positive connection of the servo motor M with the second and third pump P2, P3 and pressure is thus established on all four wheels HL, HR, VL, VR.

In 7a is a schematic cross section through an eccentric pump assembly shown. A common output shaft AA, which rotates eccentrically about a rotation axis DA, drives z. Example, designed as a piston pump elements PVL, PVR, PHA1, PHA2, wherein the pump element PVL is a second pump element P2, the pump element PVR, a third pump element P3, the pump element PHA1, an element of the first pump P1 and the pump element PHA2 a Element of the other pump P4 is (see 6 ). As a result of the arrangement, the pumps P1, P2, P3, P4 can be actuated with a uniform angular offset since the four pump elements PVL, PVR, PHA1, PHA2 are arranged mechanically offset by 90 ° with respect to the axis of rotation DA.

In 7b is a cross section of another eccentric pump assembly shown. In this case, a first part AA1 of the output shaft AA, which drives pump elements PHA1, PHA2, is arranged with a rotation angle offset of 90 ° with respect to a second part AA2 of the output shaft AA, which drives pump elements PVL, PVR. In this arrangement, directions of movement of the z. B. trained as a piston pump elements PHA1, PHA2, PVL, PVR oriented in parallel. Such a construction is space-optimized, since no star arrangement is to be provided. However, deviating from the arrangement described arrangements are possible. Shown is also a clutch 28 which mechanically connects the first part AA1 to the second part AA2 of the output shaft AA or separates a mechanical connection.

This in 6 Brake system shown here can be used in particular in electric and hybrid vehicles, especially in vehicles in which a rear axle is electrically driven. Since the rear wheels HL, HR are braked by a power brake, by means of the in 6 illustrated brake system 1 smooth transition between regenerative deceleration (recuperation mode) and conventional deceleration is possible.

In 8th is a braking system 1 shown in a seventh embodiment. Here it is shown that the brake system 1 a left rear brake light BHL, a right rear brake light BHR and a middle rear brake light BHM includes. A brake light can also be referred to as a brake light. A first control unit 17 generates control signals for the middle rear brake light BHM, while a second control unit 19 Control signals for the left rear brake light BHL and the right rear brake light BHR generated. For this purpose, the middle rear brake light BHM signaling only with the first control unit 17 connected while the remaining brake lights BHL, BHR signaling only with the second control unit 19 are connected. The brake lights BHM, BHL, BHR can indicate a braking request of the vehicle to other road users.

In the case of a partially, fully or fully automatically operated vehicle, it is desirable that, for any single fault in an electric brake circuit, safe driving can be maintained for a limited time. The driver may, for example, be distracted from the traffic situation when the single fault occurs, whereby a predetermined time may elapse after a request to take over a vehicle guidance until the driver takes over the vehicle guidance. It is also desirable to have a single fault in the brake system 1 at least one brake light BHL, BHR, BHM, but better all brake lights BHL, BHR, BHM, are activated and thus light up. Includes the brake system 1 Several electric brake circuits, so it is desirable that the brake system 1 is non-reactive. Reaction-free here means that a single error in a first electrical brake circuit must not lead to a following error in another electric brake circuit.

An in 8th illustrated arrangement 2 can hereby like in 1 be shown represented. A first and a second electrical brake circuit of the in 8th illustrated brake system 1 can be used according to the explanations given in the 1 illustrated brake system 1 are formed.

In particular, in an error operation in which there is a single error in the first or the second electrical brake circuit, the first control device 17 and the second control device 19 in each case from the respective control devices 17 . 19 received signals and / or from in the control devices 17 . 19 calculated Signals control signals for controlling the / the respective control device 17 . 19 associated brake light / r BHM, BHL, BHR produce. In this case, the two control devices 17 . 19 independently of each other of the respective control device 17 . 19 activate assigned brake lights BHM, BHL, BHR.

In a normal operation, the first control device 17 and the second control device 19 the received and internally calculated signals via a CAN bus 21 change. Thus, in normal operation, for example, the first control device 17 take over the function of a master and generate from all received and internally calculated signals, a drive signal for both the middle rear brake light BHM and for the left and right rear brake lights BHL, BHR. The drive signals for the left and right rear brake lights BHL, BHR may be the first control device 17 over the CAN bus 21 to the second control device 19 transmit, which then transmits the drive signal to these brake lights BHL, BHR. Between such a normal operation and a completely independent control of the brake lights BHR, BHL, BHM by the corresponding control devices 17 . 19 Further degradation possibilities, depending on the detected error, can be provided.

It is also possible to power drivers in the first control device 17 as well as in the second control device 19 the power drivers provide power to operate the respective brake lights BHM, BHL, BHR. Here, in particular for reasons of symmetry, the middle rear brake light BHM of the first control device 17 and the left and right rear brake lights BHL, BHR from the second controller 19 be controlled. In the case of a short circuit in a brake light BHM, BHL, BHR can in this case a power driver of the corresponding control device 17 . 19 however, the power driver may become the remaining controller 17 . 19 continue to be functional and control the corresponding brake lights BHM, BHL, BHR.

In 9 is a braking system 1 shown in an eighth embodiment. Unlike the in 8th illustrated brake system 1 the brake lights BHM, BHL, BHR are controlled by an on-board control unit BCM. For this purpose, the onboard power supply control unit BCM is designed such that a single fault in the first electric brake circuit or in the second electric brake circuit has no effect on the respective remaining electric brake circuit. The middle rear brake light BHM is through a supply line 29 and a power control element 30 supplied with electrical energy. The power control element 30 of the middle rear brake light BHM is here by the first control device 17 driven. The middle rear brake light BHM is here from the first battery 18 supplied with electrical energy. Accordingly, the left rear brake light BHL via a supply line 31 and a power control element 32 and the right rear brake light BHR through the supply line 31 and a power control element 33 with electrical energy from the second battery 20 provided. The power control elements 32 . 33 in this case by the second control device 19 driven. Thus, the center rear brake light BHM and the left and right rear brake lights BHL, BHR are independently supplied with electric power. For this purpose, the onboard power supply control unit BCM may have different connections, for example connections for control signals of the middle rear brake light BHM and connections for the power supply of the middle rear brake light BHM and corresponding connections for the left and the right rear brake lights BHL, BHR.

Also, the onboard power supply control unit BCM with the first and second control device 17 . 19 be connected via a data bus, such as a CAN bus or a Flexray bus. Preferably, in this case a data bus can be used, which is already installed in the vehicle and z. B. a steering wheel angle sensor and the two control devices 17 . 19 combines. Also, the onboard power supply control unit BCM to the CAN bus 21 be connected.

LIST OF REFERENCE NUMBERS

1

braking system

2

arrangement

3

brake line

4

Master Cylinder

5

surge tank

6

level sensor

7

electric brake booster

8th

Rotor angle sensor

9

brake pedal

10

force sensor

11

electromechanical valve

11a

Valve

12

check valve

13

pressure sensor

14

Low-pressure accumulator

15

wheel speed sensor

16

sensors

17

first control device

18

first battery

19

second control device

20

second battery

21

CAN bus

22

pressure sensor

23

supply line

24

data line

26

data line

27

data line

28

clutch

29

supply line

30

Power control element

31

supply line

32

Power control element

33

Power control element

PVL

pump element

PVR

pump element

PHA1

pump element

PHA2

pump element

AA

output shaft

AA1

first part of the output shaft

AA2

second part of the output shaft

BHM

middle rear brake light

BHL

left rear brake light

BHR

right rear brake light

BCM

On-board control unit

P1

first pump

P2

second pump

P3

third pump

P4

another pump

M

servomotor

MR

right rear wheel

HL

left rear wheel

VR

right front wheel

VL

left front wheel

F _brake

braking force

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102011078118 A1 [0003]
• DE 102008041760 A1 [0004]
• WO 2009/015973 A1 [0005]

Cited non-patent literature

• ECE-R13H [0062]
• ECE-R13H [0065]
• ECE-R13H [0081]

Claims (10)

Braking system of a vehicle, in particular a partially, highly or fully automatically operable vehicle, wherein the brake system ( 1 ) comprises a first brake circuit and at least one further brake circuit, wherein at least the first brake circuit only a foreign power braking or both an external power braking and an auxiliary power braking of the vehicle is feasible, characterized in that in a normal operation of the vehicle, the external power braking is carried out such that a first predetermined braking force distribution on rotatable wheels (HR, HL, VR, VL) of the vehicle is adjustable. Braking system according to claim 1, characterized in that the brake system is designed such that in case of failure of the external power braking by the first brake circuit, a braking force can be generated such that a further predetermined braking force distribution, which is different from the first predetermined braking force distribution, is adjustable by the Fremdkraftbremsung the braking force generated in normal operation is higher than a generated in case of failure of the power brake in the first brake circuit braking force. Brake system according to one of claims 1 or 2, characterized in that the first brake circuits is a hydraulic brake circuit, wherein the first brake circuit is an open brake circuit. Brake system according to claim 3, characterized in that the open brake circuit through a valve ( 11a ) of a master cylinder ( 4 ) is fluid-technically separable. Brake system according to one of claims 3 or 4, characterized in that the open brake circuit is assigned to the rear wheels (HR, HL). Brake system according to one of claims 3 to 5, characterized in that the brake system comprises two further hydraulic brake circuits, each associated with a front wheel (VR, VL). Brake system according to one of the preceding claims, characterized in that the brake system comprises a drive means for a first and a further pumping means, wherein the first pumping means is associated with a first hydraulic brake circuit and the further pumping means is associated with a further hydraulic brake circuit, wherein the pumping means simultaneously by the drive means are operable, wherein between the drive device and the further pumping means, a connecting device is arranged, wherein by means of the connecting device, a frictional connection between the drive device and the further pumping device is separable. Brake system according to one of the preceding claims, characterized in that one of the brake circuits comprises at least one electromechanical brake device. Braking system according to one of the preceding claims, characterized in that the brake system comprises a first and at least one further brake light (BHM, BHL, BHR), wherein the brake system comprises a first control device ( 17 ) and at least one further control device ( 19 ), wherein the first brake light (BHM) exclusively by means of or via the first control device ( 17 ) is controllable, wherein the at least one further brake light (BHL, BHR) exclusively by means of or via the further control device ( 19 ) is controllable. A method for generating a braking force in a vehicle, in particular in a partially, fully or fully automatically operable vehicle, wherein in each case a braking force is generated by a first brake circuit and by at least one further brake circuit, wherein by the first brake circuit a power brake or a power brake of the Vehicle is performed, characterized in that in a normal operation of the vehicle, the external power braking or the auxiliary power brake is performed such that a first predetermined braking force distribution on rotatable wheels (HL, HR, VL, VR) of the vehicle is set.

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