DE102011087905A1 - Brake system for e.g. electric car, has brake circuit connected to master brake cylinder and provided with wheel brake cylinder that exercises braking torque on wheel of vehicle, where wheel is assigned with wheel brake cylinder - Google Patents

Abstract

The system has a hydraulic brake device whose brake circuit (12a) is connected to a master brake cylinder (10) and provided with a wheel brake cylinder (14a). The wheel brake cylinder exercises a first braking torque on a first of a vehicle. A generator device (16) exercises a second braking torque on a second wheel of the vehicle. Another brake circuit (12b) connected to the master brake cylinder is provided with another wheel brake cylinder (14b) that exercises a third braking torque on a third wheel of the vehicle, where the third wheel is assigned with the latter wheel brake cylinder. An independent claim is also included for a method for decelerating three wheels of a vehicle.

Description

The invention relates to a braking system for a vehicle. Furthermore, the invention relates to a method for braking at least three wheels of a vehicle.

State of the art

In the DE 10 2008 017 480 A1 For example, a method for operating a vehicle brake system and a vehicle brake system are described. The vehicle brake system has a master brake cylinder with a brake circuit connected thereto, which connects two hydraulically actuated wheel brakes of two wheels to the master brake cylinder. In addition, the vehicle brake system comprises an electric motor which can be used as a generator, by means of which two further wheels can be braked without a hydraulically actuated wheel brake.

Disclosure of the invention

The invention provides a braking system for a vehicle having the features of claim 1 and a method for braking at least three wheels of a vehicle having the features of claim 9.

Advantages of the invention

When using the present invention, a rapid and for a driver comfortable braking of the at least three wheels is reliably ensured even in the event of a functional impairment of at least one brake circuit or the generator device. Even if one of the two (hydraulic) brake circuits, for example due to leakage, completely fails, the other brake circuit is still functional and can reliably support the regenerative braking effect of the generator device. Accordingly, even with a functional impairment of the generator device by means of the two brake circuits, a large number of regulations and backup strategies, in particular a wheel-specific ABS control, can still be implemented.

It should be noted that in addition to the multi-circuiting of the hydraulic brake device, the present invention enables a wheel-specific ABS control at least on the first wheel and on the third wheel. Accordingly, an ESP control can also be carried out with a corresponding design of the two brake circuits on the first wheel and on the third wheel. By means of a corresponding design of the generator device, such advantageous control can also be carried out on the second wheel and on the fourth wheel.

The technology of the invention allows for small drawbacks to the functionality of a braking system whose advantageous simplicity. A significant advantage of the technology according to the invention is the complete feasibility of essential functions with significant simplification of the braking system.

By means of the present invention, a comparatively lightweight and relatively simple brake system can be realized. The brake system is simplified in particular in comparison with a conventional brake system in that at least the second wheel can be braked without the equipment having a wheel brake cylinder associated therewith. Thus, in particular when equipped with a three-wheeled vehicle with the brake system, a wheel brake cylinder can be saved. This can also be described in such a way that an axle of the vehicle equipped with the brake system can be braked without being equipped with one of these separately assigned hydraulic brake devices.

When the brake system is used in a vehicle with four wheels, a fourth braking torque can be exerted on a wheel brake cylinder-free fourth wheel of the vehicle that can be assigned to the generator device by means of the generator device. Thus, when inserting the brake system in a four-wheeled vehicle, two wheel brake cylinders can be saved. In particular, the electric drive motor of the vehicle may be used as a generator device for braking at least the second wheel, in particular for braking the second wheel and the fourth wheel, instead of the wheel brake cylinders that can be saved. As a result of this multifunctionality of the generator device, the comparatively easy and relatively simple design of the brake system can be maintained even when the brake system is being used in a vehicle.

Preferably, the brake system has exactly two brake circuits comprising the first brake circuit and the second brake circuit, wherein the brake system comprises exactly two wheel brake cylinders comprising the first wheel brake cylinder and the second wheel brake cylinder. This advantageous simple construction of the brake system ensures a low weight, low production costs and a minimum space requirement of the brake system.

In an advantageous embodiment, the brake system has exactly four electrically controllable valves comprising a Radeinlassventil the first brake circuit, a Radauslassventil the first brake circuit, a Radeinlassventil the second brake circuit and a Radauslassventil the second brake circuit. Due to the small number of electrically controllable valves of the brake system eliminates the cost of additional valves. by virtue of The reduced number of electrically controllable valves also the control electronics can be made relatively inexpensive.

Alternatively, the brake system may comprise exactly eight electrically controllable valves, a wheel inlet valve of the first brake circuit, a wheel outlet valve of the first brake circuit, a high pressure switching valve of the first brake circuit, a switching valve of the first brake circuit, a wheel inlet valve of the second brake circuit, a Radauslassventil the second brake circuit, a high-pressure switching valve of the second brake circuit and a switching valve of the second brake circuit. Also, this brake system is in comparison with other conventional brake systems still inexpensive to produce and operable by means of a comparatively simple electronics. By using conventional manner already existing on a brake system components, the brake system can be manufactured with a relatively low cost and at low cost in mass production.

In an advantageous development, the brake system comprises a control device, by means of which, taking into account an operating strength of an operation of a brake actuator, a target total delay size can be fixed and the specified target total delay variable with a first Kann-size with respect to a by means of the generator device on the second wheel maximally exercisable second Kann -Bremsmoments or with a sum of the first Kann-size and a second Kann-size with respect to a maximum by means of the generator device on the fourth wheel can be exercised fourth Kann-braking torque is comparable. Thus, the operation of the generator device can be advantageously adapted to the operation of the brake operating member by the driver and to the applicability of the generator device.

For example, if the predetermined target total deceleration amount is less than and / or equal to the first clot size or the sum of the first clone size and the second clone size, the controller may be configured to include the wheel inlet valve of the first brake circuit and the wheel inlet valve of the second Each brake circuit to control in a closed state. Thus, by decoupling the first wheel brake cylinder and the second wheel brake cylinder from the master brake cylinder, a buildup of brake pressure in them can be prevented. The attributable braking effect of the first wheel brake cylinder and the second wheel brake cylinder can be used by an increased use of the generator device to charge a vehicle battery faster. This improves the recuperation efficiency of the brake system. Thus, a fuel consumption and a pollutant emission of the equipped with the braking system vehicle are additionally reduced. In addition, it is ensured that, despite a high recuperation efficiency, a target total deceleration quantity predetermined by the driver by means of the actuating strength is not exceeded.

In addition, if the predetermined target total deceleration amount is greater than the first clot size or the sum of the first clone size and the second clone size, the controller may be configured to include the wheel inlet valve of the first brake circuit and / or the wheel inlet valve of the second Control brake circuit in an at least partially open state. Thus, the brake system can also respond to an omitted / reduced applicability of the generator device, for example, due to too low a speed of the wheels of the vehicle, or too low a vehicle speed, and / or an already charged vehicle battery. Thus, even in situations in which the generator device is used only to a limited extent or in which the driver requests a comparatively large vehicle deceleration, a reliable deceleration of the vehicle can be carried out in accordance with the actuation strength effected by the driver.

The realizable by means of the present invention braking system is well suited for a simple, small and inexpensive vehicle, especially for such an electric vehicle due to its relatively low weight and low production costs.

The advantages described in the above paragraphs are also ensured in a corresponding method for braking at least three wheels of a vehicle.

The first wheel brake cylinder and the second wheel brake cylinder may be understood to mean a hydraulically actuable wheel brake, such as a wheel brake caliper. However, it should be noted that a wheel brake cylinder can be understood as any (hydraulic) wheel brake device by means of which a mechanical force can be exerted on a contacted wheel via a pressure build-up in an inner end volume of the wheel brake device. Under a wheel brake cylinder-loose wheel is thus also a hydraulic-wheel brake device-free wheel to understand, which can only be braked by means of the generator device.

Accordingly, the first brake circuit and the second brake circuit hydraulic brake circuits to understand. Although the generator device can be rewritten as an "electrical brake circuit", the term "brake circuit" is used here. synonymous with "hydraulic brake circuit" used. The limitation of the number of brake circuits of the brake system to two thus does not exclude the equipment of the brake system with the generator device in addition to the two (hydraulic) brake circuits.

Brief description of the drawings

Further features and advantages of the present invention will be explained below with reference to the figures. Show it:

1 a schematic representation of a first embodiment of the brake system;

2 a plurality of components of a second embodiment of the brake system;

3 a schematic representation of a third embodiment of the brake system; and

4 a flowchart for illustrating an embodiment of the method.

Embodiments of the invention

1 shows a schematic representation of a first embodiment of the brake system.

This in 1 schematically reproduced brake system can be used in a vehicle. The brake system comprises a hydraulic brake device with a master brake cylinder 10 , one on the master cylinder 10 connected first brake circuit 12a with a first wheel brake cylinder 14a and one also on the master cylinder 10 connected second brake circuit 12b with a second wheel brake cylinder 14b ,

In addition, the brake system comprises a generator device 16 which can be designed, for example, as a generator-operable electromechanical drive motor. The feasibility of the generator device 16 however, is not limited to any particular type of motor and / or generator.

By means of the first wheel brake cylinder 14a is a first braking torque (not equal to zero) on a first wheel brake cylinder 14a assignable / associated first wheel of the vehicle equipped with the braking system exercisable. By means of the generator device 16 may be a second braking torque (not equal to zero) on one of the generator device 16 assignable / assigned wheel brake cylinder-loose second wheel of the vehicle are exercised. Thus eliminating the need for a wheel brake cylinder for the second wheel when equipping a vehicle with the brake system described here. Furthermore, by means of the second wheel brake cylinder 14b a third braking torque (not equal to zero) on a second wheel brake cylinder 14b assignable / associated third wheel of the vehicle are exercised.

Optionally, the generator device 16 additionally designed to have a fourth braking torque (not equal to zero) on one of the generator means 16 Assign assignable / associated another wheel brake cylinder-loose fourth wheel of the vehicle. Thus, it is also possible to dispense with the equipment of the fourth wheel with a wheel brake cylinder. The generator device 16 In particular, it may be designed so that it acts on a common axis, on which the second wheel and the fourth wheel are arranged on the vehicle. Alternatively, the generator means 16 also have two separate subunits, of which a first on the second wheel and a second on the fourth wheel are arranged so that they have the advantageous function of the generator means 16 exercise.

It should be noted that the brake system preferably exactly two brake circuits 12a and 12b (comprising the first brake circuit 12a and the second brake circuit 12b ) having. Due to the two-circuit design of the brake system, an advantageous safety standard of the brake system is ensured. In particular, the driver has himself after occurrence of a functional impairment of one of the two brake circuits 12a or 12b still the possibility of the vehicle over the use of the other brake circuit 12a or 12b and the use of the generator device 16 in a simple way to bring to a standstill. At the same time, the driver can also be at a functional impairment of the generator device 16 over the two brake circuits 12a and 12b still directly in the wheel brake cylinder 14a and 14b brake in and thus bring the vehicle in a simple manner and reliably to a standstill.

In addition, the brake system preferably has exactly two wheel brake cylinders 14a and 14b (comprising the first wheel brake cylinder 14a and the second wheel brake cylinder 14b ) on. The small number of wheel brake cylinders 14a and 14b The braking system ensures low production costs, minimizes the space requirement and reduces the weight of the brake system. At the same time, despite the small number of only two wheel brake cylinders 14a and 14b by means of the brake system described here in a three-wheeled vehicle on all three wheels a braking torque (not equal to zero) on this (preferably individually) exercisable. Accordingly, even with a four-wheeled vehicle, all four wheels are described by means of the one described here Braking (non-zero) on each of these wheels (preferably individually) exercisable.

Under the first wheel brake cylinder 14a and the second wheel brake cylinder 14b can be understood a hydraulically actuated wheel brake. For example, the first wheel brake cylinder 14a and / or the second wheel brake cylinder 14b to be a wheel brake caliper. It is noted, however, that the feasibility of the wheel brake cylinder 14a and 14b are not limited to a particular type of hydraulically actuated wheel brake. Instead, under a wheel brake cylinder 14a and 14b a (hydraulic) braking device can be understood, by means of which a mechanical force can be exerted on an assigned / adjacent / contacted wheel via a pressure build-up in an inner end volume of the braking device.

It is expressly understood that under the wheel brake cylinder-loose second wheel, or under the wheel brake cylinder-loose fourth wheel, a wheel of the vehicle equipped with the braking system is understood, to which neither by means of a hydraulically actuated wheel brake, such as a Radbremszange , nor by means of an electromechanically actuated wheel brake unlike the generator device 16 a braking torque (not equal to zero) is exercisable. The second braking torque exerted on the wheel brake cylinder-less second wheel, or the fourth braking torque exerted on the wheel brake cylinder-less fourth wheel, thus results exclusively from the generator braking torque of the generator device. One can also rewrite this so that at or in the vicinity of the wheel brake cylinder-loose second wheel, or the wheel brake cylinder-loose fourth wheel, no hydraulically actuated wheel brake and no electromechanically actuated wheel brake unlike the generator device 16 is appropriate. The vehicle equipped with the brake system thus preferably has exactly two wheel brake cylinders 14a and 14b (comprising the first wheel brake cylinder 14a and the second wheel brake cylinder 14b ) and no electromechanically actuated wheel brake unlike the generator device 16 on. In a three-wheeled vehicle, the total braking torque exerted on the three wheels is thus the sum of that of the first wheel brake cylinder 14a exerted first braking torque, from the means of the generator device 16 exerted second braking torque and from the means of the second wheel brake cylinder 14b exerted third braking torque. Accordingly, in a four-wheeled vehicle, the total braking torque applied to the four wheels is equal to the sum of that of the first wheel brake cylinder 14a exerted first braking torque, from the means of the generator device 16 (on the second wheel) exerted second braking torque, from the means of the second wheel brake cylinder 14b exerted third braking torque and from the means of the generator device 16 (on the fourth wheel) exerted fourth braking torque.

The brake system is preferably designed such that the wheel brake cylinders 14a and 14b associated with a common axis of the vehicle equipped therewith. For example, by means of the wheel brake cylinder 14a and 14b a front axle of the vehicle equipped with the braking system be braked while using the generator means 16 the rear axle of the vehicle can be braked. By the assignment of the two wheel brake cylinders 14a and 14b To the front axle it is possible to ensure that the stabilization of the vehicle is achieved by reducing the regenerative braking torque on the rear axle and then mainly on the front axle. Thus, in particular, an ABS control for the maintenance of steerability on the front axle executable. It is noted, however, that the wheel brake cylinders 14a and 14b Also wheels can be assigned, which are arranged on a common side or diagonally on a vehicle.

Preferably, the brake system has a Radeinlassventil 18a of the first brake circuit 12a , a wheel outlet valve 20a of the first brake circuit 12a , a wheel inlet valve 18b of the second brake circuit 12b and a wheel outlet valve 20b of the second brake circuit 12b on. Parallel to each of the wheel inlet valves 18a and 18b can be a bypass line with a check valve 19a and 19b be educated. In a preferred embodiment, the brake system has exactly the four electrically controllable valves 18a . 18b . 20a and 20b , This comparatively small number of electrically controllable valves 18a . 18b . 20a and 20b reduces the manufacturing costs, the space requirement and the weight of the brake system. In addition, the brake system with the comparatively small number of electrically controllable valves 18a . 18b . 20a and 20b be controlled by a low-cost and simply constructed electronics.

In an advantageous development, the brake system comprises a control device 22 by means of which, taking into account an actuation strength signal 24 / an actuation strength of an actuation of a brake actuation element 26 , such as a brake pedal, a target total delay can be determined. The operating force provided by a sensor (not shown) may be, for example, a driver braking force, a driver brake pressure and / or a brake actuation travel, or an adjustment travel of an adjustable component of the brake actuation element 26 (eg a bar path). The control device 22 however, it may also be designed to take into account further variables in determining the target total delay quantity.

It should be noted that the control device 22 is preferably designed for a three-wheeled vehicle, the first braking torque to be exerted on the first wheel, the second braking torque to be exerted on the second wheel and the third braking torque to be applied to the third wheel such that the sum of the first wheel brake cylinder 14a exerted first braking torque, from the means of the generator device 16 exerted second braking torque and from the means of the second wheel brake cylinder 14b applied third braking torque equal to the target total delay amount, or a total braking torque corresponding to the target total delay amount is. Preferably, the control device 22 for a four-wheeled vehicle preferably designed to set the four braking moments to be exerted on the four wheels so that the sum of the means of the first wheel brake cylinder 14a exerted first braking torque, from the means of the generator device 16 (on the second wheel) exerted second braking torque, from the means of the second wheel brake cylinder 14b exerted third braking torque and from the means of the generator device 16 (Fourth wheel) fourth braking torque is also equal to the target total delay amount, or a total braking torque corresponding to the target total delay amount is. The onset of another hydraulically actuated wheel brake or an electromechanically actuated wheel brake unlike the generator device 16 is not necessary. Likewise, eliminates the need for using the generator device 16 brake the first wheel or the third wheel additionally.

Furthermore, the control device 22 be adapted to the set target total delay quantity with a first can size with respect to a means of the generator means 16 to compare to the second wheel maximally exercisable second Kann-braking torque. This is especially true when equipping the three-wheeled vehicle with the control device 22 advantageous. In a four-wheeled vehicle, it is preferred that the control device 22 is adapted to the set target total delay amount with a sum of the first can size and a second can size with respect to one by means of the generator means 16 to settle on the fourth wheel maximum exercisable fourth Kann-braking torque. The first can size and / or the second can size can from a further electronics, for example, from a central vehicle electronics, to the control device 22 to be provided. Likewise, the control device 22 be configured to set the at least one can size, for example, taking into account a vehicle speed, a rotational speed of the wheels and / or a level of a vehicle battery.

Preferably, the control device 22 in addition, if the predetermined target total deceleration amount is less than and / or equal to the first clot size or the sum of the two clot sizes, the wheel inlet valve 18a of the first brake circuit 12a and the wheel inlet valve 18b of the second brake circuit 12b (by means of a control signal 28 ) in a closed state. As the wheel brake cylinder 14a and 14b about closing the Radeinlassventile 18a and 18b from the master cylinder 10 can be decoupled and thus no / hardly exert a braking effect on the wheels assigned to them, the total delay requested by the driver with a full applicability of the generator device 16 be used exclusively for fast charging of the vehicle battery. The advantageous design of the control device thus allows frequent use of the generator device 16 for comparatively fast charging of a vehicle battery, at the same time the reliable compliance of the driver by the operation of the brake actuator 26 predetermined total braking torque is guaranteed.

In addition, the control device 22 be designed to, if the set target total delay amount is greater than the first can size and sum of the two can sizes, the wheel inlet valve 18a of the first brake circuit 12a and the wheel inlet valve 18b of the second brake circuit 12b in an at least partially open state to control. At a requested total braking torque, which by means of the generator device 16 is not or only partially exercisable, so it can via the Radeinlassventile 18a and 18b a brake pressure in the wheel brake cylinders 14a and 14b be constructed, whereby the braking effect of the generator device 16 by means of the wheel brake cylinder 14a and 14b supported or completely replaced.

The control device 22 In particular, it may be configured to carry out the method described in more detail below. With regard to a further feasibility of the control device 22 is therefore referred to.

As a supplement to the above components can be at least one of the brake circuits 12a and 12b another storage chamber 30a and 30b and / or a pump 32a and 32b exhibit. Unless each of the brake circuits 12a and 12b via its own pump 32a and 32b This can be on a common shaft 34 an engine 36 be arranged. To operate the pumps 32a and 32b is an engine 36 sufficient with a comparatively low engine power. In addition, at least one of the brake circuits 12a and 12b another pressure sensor 38 have, its (not outlined) sensor signal also by means of the control device 22 can be considered. Preferably, the at least one pressure sensor 38 also be used to match the driver's brake request with the set braking effect. In an ABS control, the brake system in the hydraulic range can be modulated by a conventional method. In the regenerative range, an ABS control can also be carried out by modulating the removed regenerative power.

It should be noted that the equipment of the brake system in 1 with a brake booster 40 , such as a vacuum brake booster, is merely optional. In particular, when equipping a small vehicle with the brake system can on the brake booster 40 also be waived. As the generator device 16 is designed to assist the driver in a deceleration of the vehicle by force, the braking power required for braking the vehicle is reduced so far that on the brake booster 40 can be waived. A design of the brake system without the brake booster 40 is due to the generator device 16 feasible without the driver when operating the brake actuator 26 in order to decelerate the vehicle equipped with the brake system, it is necessary to apply a braking force over a normal braking force range. In addition, can be eliminated by the elimination of the usual brake booster of the trained example as a vacuum booster brake booster 40 a vacuum pump can be saved on the vehicle.

2 shows several components of a second embodiment of the brake system.

This in 2 about its components reproduced brake system has exactly two Radeinlassventile 18a and 18b and exactly two wheel outlet valves 20a and 20b on. The valves 18a . 18b . 20a and 20b can in a pump housing 50 be used. The pump housing 50 thus preferably has exactly four openings 51 for inserting the valves 18a . 18b . 20a and 20b on.

In the pump housing 50 are also a variety of not further described components of the pump 32a and 32b the braking system used. Also the reproduced in their individual components storage chambers 30a and 30b can on the pump housing 50 be arranged firmly. The at least one pressure sensor 38 can also be in the pump housing 50 to be ordered. In addition, on the pump housing 50 an engine 36 with a common wave 34 for the two pumps 32a and 32b to be assembled.

The above-described control device 22 can on a circuit board 52 be educated. Via a housing base 54 and a housing cover attachable thereto 56 can the circuit board 52 during operation of the control device 22 to be protected. In addition, at least one other electronic component 58 by means of at least one screw 60 on the housing base 54 be tightened and thus protected during operation of the brake system.

3 shows a schematic representation of a third embodiment of the braking system.

This in 3 schematically illustrated brake system comprises the components already described above 10 to 40 , In addition, each of the brake circuits 12a and 12b a high pressure switching valve 70a or 70b and a changeover valve 72a or 72b , The brake system thus has exactly eight electrically controllable valves 18a . 18b . 20a . 20b . 70a . 70b . 72a and 72b on.

Also parallel to the switching valves can each have a forwarding with a check valve 73a or 73b be educated. In addition, between a Radauslassventil 20a and 20b and an associated high pressure switching valve 70a or 70b a pressure relief valve 74a or 74b be aligned so that a brake fluid transfer from the at least partially opened high-pressure switching valve 70a or 70b to the associated Radauslassventil 20a or 20b is prevented. The advantageous technology described above can thus also be applied to an ESP system. Likewise, some basic safety functions, such as in particular an ESP function and / or the select-low principle, can be carried out to stabilize the vehicle.

Also in 3 reproduced brake system can without the brake booster 40 be used. By means of the generator device 16 executable assistance of the driver during a deceleration of the vehicle, the brake booster 40 be saved without this being associated with a loss of comfort for the driver.

The brake system is preferably designed such that the wheel brake cylinders 14a and 14b a common axis of a vehicle, preferably the front axle, are assignable. By means of the generator device 16 can in this case the rear axle of the vehicle are braked. It is noted, however, that the wheel brake cylinders 14a and 14b Also wheels can be assigned, which are arranged on a common side or diagonally on a vehicle.

The brake systems described in the above paragraphs can be used in a variety of different vehicle types. Such a vehicle may be, for example, an electric vehicle or a hybrid vehicle. Preferably, the realizable by means of the technology of the invention brake system is used in a vehicle, which has only an electric motor as a drive motor. However, as a supplement to such an electric motor equipped with this braking system vehicle may also have an extender, a solar engine device and / or an internal combustion engine.

Particularly advantageous is the use of the braking systems described above in a vehicle with a weight of less than 750 kilograms, in particular less than 650 kilograms, preferably less than 500 kilograms. Also advantageous is the use of a realizable by means of the technology of the invention braking system in a vehicle, which is designed for a maximum speed of less than 120 km / h, for example, less than 100 km / h, preferably less than 80 km / h.

4 shows a flowchart for illustrating an embodiment of the method.

The method described in the following paragraphs, for example, by means of the above reproduced braking systems executable. It should be noted, however, that the practicability of the method is not limited to the use of such a braking system.

In carrying out the method for braking at least three wheels of a vehicle, in a method step S1, a first braking torque is exerted on a first wheel of the at least three wheels of the vehicle (exclusively) by means of a first wheel brake cylinder. The first wheel brake cylinder is part of a first brake circuit connected to a master brake cylinder. In a method step S2, a second braking torque is exerted on a wheel brake cylinder-free second wheel of the at least three wheels (exclusively) by means of a generator device. Also, in a method step S3, a third braking torque is exerted on a third wheel of the at least three wheels (exclusively) by means of a second wheel brake cylinder, which is part of a second brake circuit connected to the master brake cylinder.

If a four-wheeled vehicle is to be braked by means of the method described here, a fourth braking torque can be exerted on a wheel brake cylinder-free fourth wheel of the vehicle (exclusively) by means of the generator device in an optimal method step S4. Under the wheel brake cylinder-loose second wheel and / or the wheel brake cylinder-loose fourth wheel can be understood a wheel on which neither a hydraulic wheel brake nor an electromechanical wheel brake is arranged unlike the generator device. The second wheel and / or the third wheel can therefore also be referred to as a wheel spaced apart from a hydraulic unit comprising the two brake circuits.

The method steps S1 to S4 can all be performed together, in a specific number, individually, simultaneously and / or in any desired time sequence. This ensures the advantages already described above, the renewed description of which is omitted here.

In an advantageous development, the method also includes a method step S5, in which an actuation of a brake actuation element is set to a desired total deceleration quantity, taking into account an actuation strength. Subsequently, in the execution of the method for braking a three-wheeled vehicle in a method step S6, the specified target total deceleration quantity can be compared with a first optional variable with respect to a second optional braking torque which can be exerted on the second wheel by means of the generator device. However, in one embodiment of the method for braking a four-wheeled vehicle, in method step S6, the predetermined target total deceleration quantity may also be a sum of the first available size and a second available size with respect to a fourth maximum that can be exercised by the generator device on the fourth wheel -Bremsmoments be compared.

By carrying out the method steps S5 and S6 before the method steps S1 to S4, the use of the generator device and the two wheel brake cylinders can be optimized. In order to minimize the CO2 emissions of a hybrid or electric vehicle, it is desirable to recover as much energy as possible during braking by means of a relatively frequent insertion of the generator device and to feed it into the electrical system, or to use it to charge a vehicle battery. However, an applicability / braking action of a generator, such as a regenerative electric drive motor, depending on the speed of the vehicle, or the speed of the wheels of the vehicle, and / or the state of charge of the battery. By means of However, the method steps S1 to S4 described below can be combined / selected so that a fast charging of the vehicle battery is ensured in a reliable compliance with the predetermined by the driver total target deceleration size.

Preferably, if the predetermined target total delay quantity is less than or equal to the first can size or the sum of the first can size and the second can size, a method step S7 can be performed. During the process step S7, a wheel inlet valve of the first brake circuit and a wheel inlet valve of the second brake circuit are each controlled in a closed state. This causes, despite an actuation of the brake operating member by the driver, a pressure build-up in the first wheel brake cylinder and in the second wheel brake cylinder is (almost) prevented. Even after overcoming an air clearance / idle travel, which is possibly formed between an adjustable component of the brake operating member and an adjustable piston of the master cylinder, the hydraulic brake is thus shut off and it is not hydraulically braked despite a displacement of liquid from the master cylinder. (The process steps S1 and S3 are thus not performed during the operation of the brake operating member and the process step S7). Therefore, the requested by the driver total target deceleration size for a maximum / optimized use of the generator device can be used without causing a relation to the driver's brake request too strong braking of the vehicle. During actuation of the brake actuation element and the method step S7, it is thus only regeneratively braked (method steps S2 and / or S4). This can be done, for example, by the at least one drive motor is switched to the generator mode. The method steps S7, S2 and / or S4 therefore ensure the fastest possible charging of the vehicle battery and a significant reduction of the fuel consumption and the pollutant emission of the vehicle.

However, if the specified target total delay quantity is greater than the first available size or the sum of the first can size and the second can size, a method step S8 may also be performed. During the method step S8, the wheel inlet valve of the first brake circuit and the wheel inlet valve of the second brake circuit are controlled in an at least partially opened state. As a result, brake pressure can be exerted in the wheel brake cylinders via a displacement of brake fluid from the master brake cylinder in the direction of the wheel brake cylinders. Thus, all method steps S1 to S4 can be executed during the actuation of the brake actuation element and the method step S8. By braking the first wheel and the third wheel by means of the wheel brake cylinder, a non-existent / temporally decreasing applicability of the generator device can be reliably compensated. Even with a sudden elimination of the applicability of the generator device thus predetermined by the driver target total delay size is still reliably executable.

The method step S8 can be carried out in particular after the method step S7 if, due to the decreasing speed of the wheels or the reduced speed of the vehicle, the (full) applicability of the generator device is no longer given. By open-controlling the Radeinlassventile and thus causing the activation of the hydraulic connection between the master cylinder and the two wheel brake cylinders during the process step S8, the executed total braking torque can be kept constant despite the temporally decreasing applicability of the generator device. Even after a complete elimination of the applicability of the generator device, the hydraulic pressure in both wheel brake cylinders can be increased sufficiently to bring the vehicle to a standstill.

By at least partially opening the Radeinlassventile during the process step S8, the brake actuator can be easily moved in the direction of actuation. One often speaks of a slipping of the brake actuator. However, such a slipping of the brake actuator is hardly perceived by a driver as disadvantageous because he quickly gets used to it.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 102008017480 A1 [0002]

Claims (13)

A brake system for a vehicle comprising: a hydraulic brake device including: a master cylinder ( 10 ); and one on the master cylinder ( 10 ) connected first brake circuit ( 12a ) with a first wheel brake cylinder ( 14a ), by means of which a first braking torque on a the first wheel brake cylinder ( 14a ) is assignable first wheel of the vehicle exercisable; and a generator device ( 16 ), by means of which a second braking torque to one of the generator device ( 16 ) is assignable wheel brake cylinder-loose second wheel of the vehicle exercisable; characterized by a on the master cylinder ( 10 ) connected second brake circuit ( 12b ) of the hydraulic brake device with a second wheel brake cylinder ( 14b ), by means of which a third braking torque on a second wheel brake cylinder ( 14b ) assignable third wheel of the vehicle is exercisable. Braking system according to claim 1, wherein by means of the generator device ( 16 ) a fourth braking torque on one of the generator device ( 16 ) is assignable wheel brake cylinder-loose fourth wheel of the vehicle exercisable. Brake system according to claim 1 or 2, wherein the brake system has exactly two brake circuits ( 12a . 12b ) comprising the first brake circuit ( 12a ) and the second brake circuit ( 12b ), and wherein the brake system exactly two wheel brake cylinder ( 14a . 14b ) comprising the first wheel brake cylinder ( 14a ) and the second wheel brake cylinder ( 14b ) having. Brake system according to claim 3, wherein the brake system has exactly four electrically controllable valves ( 18a . 18b . 29a . 29b ) comprising a wheel inlet valve ( 18a ) of the first brake circuit ( 12a ), a wheel outlet valve ( 20a ) of the first brake circuit ( 12a ), a wheel inlet valve ( 18b ) of the second brake circuit ( 12b ) and a wheel outlet valve ( 20b ) of the second brake circuit ( 12b ) having. Brake system according to claim 3, wherein the brake system exactly eight electrically controllable valves ( 18a . 18b . 29a . 29b . 70a . 70b . 72a . 72b ) comprising a wheel inlet valve ( 18a ) of the first brake circuit ( 12a ), a wheel outlet valve ( 20a ) of the first brake circuit ( 12a ), a high pressure switching valve ( 70a ) of the first brake circuit ( 12a ), a switching valve ( 72a ) of the first brake circuit ( 12a ), a wheel inlet valve ( 18b ) of the second brake circuit ( 12b ) and a wheel outlet valve ( 20b ) of the second brake circuit ( 12b ), a high pressure switching valve ( 70b ) of the second brake circuit ( 12b ) and a switching valve ( 72b ) of the second brake circuit ( 12b ) having. Braking system according to one of the preceding claims, wherein the brake system comprises a control device ( 22 ), by means of which, taking into account an operational strength of an actuation of a brake actuation element ( 26 ), the set total target deceleration quantity can be determined with a first arbitrary size with respect to a by means of the generator device ( 16 ) to the second wheel at the maximum practicable second can-brake torque or with a sum of the first can-size and a second can-size with respect to one by means of the generator device ( 16 ) is comparable to the fourth wheel maximum exercisable fourth Kann-braking torque. A braking system according to claim 6, wherein, if the predetermined target total deceleration amount is less than and / or equal to the first clot size or the sum of the first clone size and the second clone size, the control device ( 22 ) is adapted to the wheel inlet valve ( 18a ) of the first brake circuit ( 12a ) and the wheel inlet valve ( 18b ) of the second brake circuit ( 12b ) each in a closed state to control. A braking system according to claim 6 or 7, wherein, if the predetermined target total delay quantity is greater than the first can size or the sum of the first can size and the second can size, the control device ( 22 ) is adapted to the wheel inlet valve ( 18a ) of the first brake circuit ( 12a ) and / or the wheel inlet valve ( 18b ) of the second brake circuit ( 12b ) in an at least partially open state to control. Method for braking at least three wheels of a vehicle, comprising the steps of: applying a first braking torque to a first wheel of the at least three wheels by means of a first wheel brake cylinder ( 14a ) one on a master cylinder ( 10 ) connected first brake circuit ( 12a ) (S1); and applying a second braking torque to a wheel brake cylinder-free second wheel of the at least three wheels by means of a generator device ( 16 ) (S2); characterized by the step of: applying a third braking torque to a third wheel of the at least three wheels by means of a second wheel brake cylinder ( 14b ) one on the master cylinder ( 10 ) connected second brake circuit ( 12b ) (S3). Method according to claim 9, wherein by means of the generator device ( 16 ) a fourth braking torque is exerted on a wheel brake cylinder-loose fourth wheel of the vehicle (S4). The method of claim 9 or 10, wherein taking into account an operating strength of a Actuation of a brake actuation element ( 26 ) is determined (S5), and wherein the predetermined target total delay quantity with a first Can-size with respect to a means of the generator means (S5) 16 ) to the second wheel at the maximum practicable second can-brake torque or with a sum of the first can-size and a second can-size with respect to one by means of the generator device ( 16 ) is compared to the fourth wheel maximum executable fourth can-brake torque (S6). The method of claim 11, wherein, if the predetermined target total deceleration amount is less than or equal to the first clot size or the sum of the first clone size and the second clone size, a wheel inlet valve ( 18a ) of the first brake circuit ( 12a ) and a wheel inlet valve ( 18b ) of the second brake circuit ( 12b ) are each controlled in a closed state (S7). The method of claim 11 or 12, wherein, if the predetermined target total deceleration amount is greater than the first clot size or the sum of the first clone size and the second clone size, the wheel inlet valve ( 18a ) of the first brake circuit ( 12a ) and / or the wheel inlet valve ( 18b ) of the second brake circuit ( 12b ) are controlled in an at least partially opened state (S8).

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