Control unit and method for operating a braking system of a vehicle

Abstract

The invention relates to a control unit (40) for a brake system of a vehicle, wherein the control unit (40) is designed to detect or estimate, at least by means of a sensor signal (10) provided by a sensor (30) regarding an adjustment travel of a driver brake force transmission component (24) of a brake actuating element (22) of the brake system or a booster force transmission component (28) of a brake force booster (26) of the brake system, whether an adjustable piston (21) of a master brake cylinder (20) of the brake system has been adjusted from its starting position by a braking travel (s) equal to a predetermined limit braking travel (s0) into the master brake cylinder (20), and, if necessary, to output at least one control signal (14) to a pump control (36) of at least one hydraulic pump (34) of the brake system, wherein the pump control (36) can be activated by means of the at least one control signal (14) in such a way that brake fluid can be conveyed from a brake fluid reservoir (32) of the brake system to at least one wheel brake cylinder (38) of the brake system by means of the at least one hydraulic pump (34) controlled by the pump control (36). The invention also relates to a method for operating a brake system of a vehicle.

Description

Technical Field

[0001] The invention relates to a control unit for a brake system of a vehicle, a brake booster for a brake system of a vehicle and a brake system for a vehicle. The invention also relates to a method for operating a brake system of a vehicle. Background Art

[0002] From the prior art, brake systems are known in which the driver of a vehicle equipped with a corresponding brake system can brake by actuating a brake operating element / brake pedal of the vehicle via a master brake cylinder of the corresponding brake system into at least one wheel brake cylinder hydraulically connected to the master brake cylinder, wherein the driver is simultaneously supported in terms of force by a brake booster of the corresponding brake system. Such a brake system is disclosed, for example, in DE 10 2010 001 939 A1. Summary of the invention

[0003] The invention provides a control unit for a brake system of a vehicle, a brake booster for a brake system of a vehicle, a brake system for a vehicle and a method for operating a brake system of a vehicle.

[0004] In a control unit for a brake system of a vehicle, the control unit is designed to: identify or estimate, at least by means of a sensor signal provided by a sensor regarding an adjustment travel of a driver brake force transmission component of a brake operating element of the brake system or a booster force transmission component of a brake force booster of the brake system, whether an adjustable piston of a master brake cylinder of the brake system has been adjusted from its starting position into the master brake cylinder by a braking travel equal to a predetermined limit braking travel, and to output at least one control signal to a pump control mechanism of at least one hydraulic pump of the brake system, wherein the pump control mechanism can be activated by means of the at least one control signal in such a way that brake fluid can be delivered from a brake fluid reservoir of the brake system to at least one wheel brake cylinder of the brake system by means of at least one hydraulic pump driven by the pump control mechanism.

[0005] A brake booster for a vehicle brake system has a control unit as described above.

[0006] A braking system for a vehicle comprises: a control unit according to the above description; a master brake cylinder with at least the adjustable piston; a brake operating element with at least the driver brake force transmission component, through which the driver brake force can be transmitted to the adjustable piston of the master brake cylinder; a brake force booster with at least the booster force transmission component, through which the booster force provided by the brake force booster can be transmitted to the adjustable piston of the master brake cylinder; a sensor, which is designed to provide a sensor signal about the adjustment travel of the driver brake force transmission component of the brake operating element or the booster force transmission component of the brake force booster to the control unit; a brake fluid reservoir connected to the master brake cylinder; at least one hydraulic pump connected to the master brake cylinder, the hydraulic pump having its pump control mechanism; and at least one wheel brake cylinder connected to the delivery side of the at least one hydraulic pump.

[0007] A method for operating a brake system of a vehicle comprises the steps of: checking or estimating, at least by means of a sensor signal provided by a sensor regarding an adjustment travel of a driver's brake force transmission component of a brake operating element of the brake system or a booster force transmission component of a brake force booster of the brake system, whether an adjustable piston of a master brake cylinder of the brake system has been adjusted from its starting position to a braking travel equal to a predetermined limit braking travel into the master brake cylinder; and if it is recognized or estimated that the braking travel of the adjustable piston of the master brake cylinder is equal to the predetermined limit braking travel, activating a pump control mechanism of at least one hydraulic pump of the brake system in such a way that brake fluid is delivered from a brake fluid reservoir of the brake system to at least one wheel brake cylinder of the brake system by means of at least one hydraulic pump driven by the pump control mechanism.

[0008] The invention creates an advantageous possibility to react to situations in which the adjustable piston of a master brake cylinder of a vehicle / motor vehicle brake system is adjusted from its starting position by a braking distance equal to a predetermined limit braking distance by means of a driver braking force applied to a brake operating element of the vehicle / motor vehicle and / or by means of a booster force of a brake force booster of the brake system into the master brake cylinder by means of a braking distance equal to a predetermined limit braking distance. The limit braking distance of the adjustable piston of the master brake cylinder can in particular be understood as the maximum possible braking distance of the adjustable piston. The invention is therefore particularly suitable for situations in which no further braking into the master brake cylinder is possible because the braking distance of the adjustable piston of the master brake cylinder is already equal to the predetermined limit braking distance / maximum possible braking distance. Even if no further braking into the master brake cylinder is possible, the invention still ensures that brake fluid is conveyed into at least one wheel brake cylinder of the brake system and in this way ensures reliable braking of the corresponding vehicle / motor vehicle.

[0009] The present invention thus makes it superfluous to provide a "reserve volume" in the master brake cylinder, which conventionally should ensure that the braking stroke of the adjustable piston of the master brake cylinder is not / is hardly equal to the predetermined limit braking stroke / maximum possible braking stroke. The present invention can thus be used to reduce the length of the master brake cylinder, that is to say, to reduce the maximum extension length of the master brake cylinder along the adjustment direction of its adjustable piston. The master brake cylinder used when utilizing the present invention can thus have a smaller master brake cylinder length than a conventional / standard master brake cylinder. The brake booster cooperating with the master brake cylinder can also be designed to be correspondingly shorter along the adjustment direction of the adjustable piston of the master brake cylinder, so that the brake booster can be installed more easily on the vehicle / motor vehicle, without the brake booster having to extend (far) into the vehicle passenger space. The present invention can thus also be used to reduce the risk of injury to the driver in the event of an accident involving the driver's vehicle / motor vehicle.

[0010] It should be explicitly pointed out that the present invention does not require a current measured value for the master brake cylinder pressure present in the master brake cylinder and therefore also does not require a pre-pressure sensor in order to detect / estimate whether the braking travel of the adjustable piston of the master brake cylinder is equal to a predetermined limit braking travel. The present invention can therefore contribute to eliminating the need to equip a brake system using the present invention with a pre-pressure sensor.

[0011] The advantageous effect of the present invention may also be referred to as an MVR function (Master Cylinder Volume Replacement).

[0012] In an advantageous embodiment, the control unit is designed to detect or estimate whether the braking travel of the adjustable piston of the master brake cylinder is equal to a predetermined limit braking travel, at least by means of a sensor signal about the adjustment travel of the booster force transmission component provided by a rotation sensor or a motor current sensor of an electric motor of a brake booster designed as an electromechanical brake booster. The embodiment of the control unit described here can therefore cooperate with sensor types that are already frequently used, are relatively cost-effective and require little installation space.

[0013] The control unit is also advantageously designed to detect or estimate, taking into account additionally a travel difference signal of a travel difference sensor of a brake booster designed as an electromechanical brake booster, whether the braking travel of the adjustable piston of the master brake cylinder is equal to a predetermined limit braking travel. The embodiment of the control unit described here can therefore also cooperate with a travel difference sensor that has been used previously.

[0014] Alternatively or additionally, the control unit can also be designed to detect or estimate whether the braking travel of the adjustable piston of the master brake cylinder is equal to a predetermined limit braking travel by additionally taking into account a rod travel signal of a rod travel sensor at the driver's brake force transmission component designed as an input rod. The rod travel sensor can be manufactured more cost-effectively and requires less installation space. Therefore, the control unit described here is also suitable for using advantageous sensor types.

[0015] In another advantageous specific embodiment, if the control unit detects or estimates that the braking travel of the adjustable piston of the master brake cylinder is equal to a predetermined limit braking travel, the control unit is additionally designed to determine a setpoint variable regarding a setpoint volume flow to be delivered from the brake fluid reservoir to the at least one wheel brake cylinder at least by means of the provided sensor signal, the travel difference signal and / or the rod travel signal, and to activate the pump control by means of at least one control signal in such a way that an actual volume flow corresponding to the setpoint variable can be delivered from the brake fluid reservoir to the at least one wheel brake cylinder by means of at least one hydraulic pump controlled by the pump control. The specific embodiment of the control unit described here can therefore additionally inform the pump control of the extent to which an additional volume is delivered from the brake fluid reservoir to the at least one wheel brake cylinder.

[0016] The control unit is preferably additionally designed to determine a desired booster variable for a desired booster force to be implemented by means of the brake booster at least by means of the provided sensor signal, the travel difference signal and / or the lever travel signal, and to control the power booster by means of at least one booster control signal in such a way that the brake booster provides a booster force corresponding to the desired booster variable via the booster force transmission element. The embodiment of the control unit described here can therefore be used in particular as a brake booster control unit, thus eliminating the conventional need to equip the brake booster with an (additional) own control device.

[0017] As an advantageous further development, the control unit can additionally be designed to determine the desired booster variable according to a predetermined first characteristic curve if the control unit detects or estimates that the braking travel of the adjustable piston of the master brake cylinder is below a predetermined limit braking travel, and to determine the desired booster variable according to a predetermined second characteristic curve if the control unit detects or estimates that the braking travel of the adjustable piston of the master brake cylinder is equal to the predetermined limit braking travel. As explained more precisely below, the control unit can in this case also improve the brake actuation feel / pedal feel of the driver actuating the brake actuating element when the braking travel of the adjustable piston of the master brake cylinder is equal to the predetermined limit braking travel / maximum possible braking travel.

[0018] The aforementioned advantages are also ensured in a brake booster for a brake system of a vehicle with a corresponding control unit.

[0019] A braking system for a vehicle also has the above advantages if the braking system comprises: a corresponding control unit; a master brake cylinder with at least an adjustable piston; a brake operating element with at least a driver brake force transmission component, through which the driver brake force can be transmitted to the adjustable piston of the master brake cylinder; a brake force booster with at least a booster force transmission component, through which the booster force provided by the brake force booster can be transmitted to the adjustable piston of the master brake cylinder; a sensor designed to provide a sensor signal related to the adjustment travel of the driver brake force transmission component of the brake operating element or the booster force transmission component of the brake force booster to the control unit; a brake fluid reservoir connected to the master brake cylinder; at least one hydraulic pump connected to the master brake cylinder and having its pump-motor control mechanism; and at least one wheel brake cylinder connected to the delivery side of at least one hydraulic pump.

[0020] Furthermore, the implementation of a corresponding method for operating a brake system of a vehicle also creates the above-mentioned advantages. It is expressly pointed out that the method for operating a brake system of a vehicle can be designed in an expanded manner according to the above-explained specific embodiment of the control unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Further features and advantages of the invention are explained below with reference to the drawings.

[0022] Figure 1 A functional diagram for explaining one specific embodiment of a method for operating a brake system of a vehicle is shown; and

[0023] Figures 2a to 2f A schematic diagram of a brake system equipped with one specific embodiment of a control unit and a coordinate system for explaining the mode of operation of the control unit are shown. DETAILED DESCRIPTION

[0024] Figure 1 A functional diagram is shown for explaining one specific embodiment of a method for operating a brake system of a vehicle.

[0025] The method described below can be implemented for operating a brake system of a vehicle / motor vehicle. It is pointed out that the feasibility of the method is neither limited to a special brake system type of the described brake system nor to a special vehicle type / motor vehicle type of a vehicle / motor vehicle equipped with the brake system.

[0026] In method step S1, it is checked or estimated whether the adjustable piston of the master brake cylinder of the brake system has been adjusted from its starting position into the master brake cylinder by a braking stroke equal to a predetermined limit braking stroke. The starting position refers in particular to a position of the adjustable piston of the master brake cylinder in which a chamber of the master brake cylinder which is bounded by the adjustable piston and can be filled with / with brake fluid has a maximum volume, the volume of which can be reduced by adjusting the adjustable piston into the master brake cylinder. The adjustable piston of the master brake cylinder can in particular be a rod piston of the master brake cylinder. The predetermined limit braking stroke preferably corresponds to the maximum possible braking stroke, by which the adjustable piston of the master brake cylinder can be adjusted into the master brake cylinder at most. After the limit braking stroke has been adjusted, the piston can in particular hit a stop constructed in the master brake cylinder and thus cannot be adjusted further into the master brake cylinder.

[0027] At least with the aid of a sensor signal 10 provided by a sensor about the adjustment travel of a driver's brake force transmission component of a brake operating element of the brake system or a booster force transmission component of a brake force booster of the brake system, a check or evaluation is performed in method step S1 to see whether the braking travel of the adjustable piston of the master brake cylinder is equal to a predetermined limit braking travel. The driver's brake force transmission component is a component of the brake operating element, via which the driver's brake force can be transmitted to the adjustable piston of the master brake cylinder. The brake operating element of the brake system can be, for example, a brake pedal. The driver's brake force transmission component can be, for example, an input rod.

[0028] A booster force transmission component is a component of a brake booster, by means of which the booster force provided by the brake booster can be transmitted to an adjustable piston of the master brake cylinder. The brake booster can in particular be an electromechanical brake booster. For example, the booster piston can be referred to as the booster force transmission component of the brake booster. The term "adjustment travel" refers to the travel of the driver's brake force transmission component or the booster force transmission component from a (force-free) starting position that is brought about by the driver's brake force or the booster force.

[0029] Sensor signal 10 is preferably provided by a rotation sensor or a motor current sensor of an electric motor of a brake booster designed as an electromechanical brake booster. This type of sensor can be easily installed at an electromechanical brake booster.

[0030] Optionally, further sensor signal 12 can also be evaluated for checking or estimating whether the braking travel of the adjustable piston of the master brake cylinder is equal to a predetermined limit braking travel. The further sensor signal 12 can be, for example, a rod travel signal of a rod travel sensor for the adjustment travel of the driver brake force transmission component designed as an input rod or a travel difference signal of a travel difference sensor for the travel difference between the adjustment travel of the input rod and the adjustment travel of the booster force transmission component designed as a valve body.

[0031] Method step S1 can be repeated as often as desired. If it is detected or estimated that the braking stroke of the adjustable piston of the master brake cylinder is equal to the predetermined limit braking stroke, at least method step S2 is implemented. As method step S2, a pump-motor control of at least one hydraulic pump of the brake system is activated in such a way that brake fluid is delivered from a brake fluid reservoir of the brake system to at least one wheel brake cylinder of the brake system by means of at least one hydraulic pump driven by the pump-motor control. At least one control signal 14 is output to the pump-motor control for this purpose. Thus, even in the case where the braking stroke of the adjustable piston of the master brake cylinder is equal to the maximum possible braking stroke and therefore no further braking into the master brake cylinder is possible, a brake pressure increase in at least one wheel brake cylinder is promoted. Therefore, for implementing the method described here, a master brake cylinder type with a smaller master brake cylinder length, that is, with a smaller maximum extension length of the master brake cylinder along the adjustment direction of its adjustable piston, can be used without any problems. The brake booster cooperating with the master brake cylinder can also be designed correspondingly shorter in the adjustment direction of the adjustable piston of the master brake cylinder, which, as already explained above, reduces the risk of injury to the driver in the event of an accident involving his vehicle / motor vehicle.

[0032] When it is detected or estimated that the braking travel of the adjustable piston of the master brake cylinder is equal to the predetermined limit braking travel, a setpoint variable is preferably also determined regarding the setpoint volume flow to be delivered from the brake fluid reservoir into the at least one wheel brake. In this case, the pump control can be activated by means of at least one control signal 14 so that an actual volume flow corresponding to the setpoint variable is delivered from the brake fluid reservoir into the at least one wheel brake cylinder by means of at least one hydraulic pump driven by the pump control. The setpoint variable is determined at least by means of the sensor signal 10 and / or by means of the further sensor signal 12. The speed of the driver brake force transmission component and / or the booster force transmission component, for example, the increase or decrease over time of the adjustment travel of the input rod, the increase or decrease over time of the adjustment travel of the valve body and / or the increase or decrease over time of the travel difference can also be evaluated for determining the setpoint variable.

[0033] As an advantageous development, in (optional) method step S3, the booster force provided by the brake booster via the booster force transmission component and transmitted to the adjustable piston of the master brake cylinder can be adapted to the detected / estimated braking travel of the adjustable piston equal to a predetermined limit braking travel. The implementation of method step S3 is an advantageous development for operating the brake booster if, during the operation of the brake booster, a setpoint booster variable is determined for a setpoint booster force to be applied by means of the brake booster at least according to a first characteristic line / standard characteristic line or a second characteristic line / force balance characteristic line, and the power booster is subsequently controlled by means of at least one booster control signal 16 in such a way that the brake booster provides a booster force corresponding to the setpoint booster variable via the booster force transmission component. As explained in more detail below, if it is detected or estimated that the braking travel of the adjustable piston of the master brake cylinder is below the predetermined limit braking travel, the setpoint booster force is determined according to the first characteristic line / standard characteristic line. Correspondingly, when performing method step S3, the desired booster variable is determined according to the second characteristic line / force balance characteristic line, because it is detected or estimated that the braking travel of the adjustable piston of the master brake cylinder is equal to the predetermined limit braking travel. The second characteristic line / force balance characteristic line and the first characteristic line / standard characteristic line can be, for example, functions, which assign a specific desired booster force to the adjustment travel of the driver brake force transmission component or a desired adjustment travel of the booster force transmission component corresponding to the desired booster force or a corresponding desired travel difference between the adjustment travel of the input rod and the adjustment travel of the valve body.

[0034] The second characteristic line / force balance characteristic line and the first characteristic line / standard characteristic line are preferably determined as a function in such a way that the second characteristic line / force balance characteristic line assigns a lower setpoint booster force or a smaller setpoint booster force transmission component or a correspondingly adapted setpoint travel difference to the adjustment travel of the driver's brake force transmission component than the first characteristic line / standard characteristic line. In this way, the brake actuation feel / pedal feel of the driver actuating the brake actuating element is adjusted in such a way that the driver does not or barely perceives the reaction of the adjustable piston of the master brake cylinder to adjust the predetermined limit brake travel.

[0035] As a further advantageous supplement, method step S1 can be repeated at least once after method step S2 (and possibly method step S3) has been carried out. If in this case it is detected or estimated that the braking travel of the adjustable piston of the master brake cylinder is less than the limit braking travel, then in method step S4 the pump control can control this by means of at least one deactivation signal 18, i.e. at least one hydraulic pump controlled by the pump control is deactivated. Furthermore, in method step S5 a setpoint booster variable is determined for the setpoint booster force to be carried out by the brake booster according to the first characteristic curve / standard characteristic curve, so that the brake booster is then operated again "according to standard".

[0036] Figures 2a to 2f A schematic diagram of a brake system equipped with one specific embodiment of a control unit and a coordinate system for explaining the mode of operation of the control unit are shown.

[0037] exist Figure 2a The brake system schematically shown in FIG. 1 has a master brake cylinder 20 with at least one adjustable piston 21. The adjustable piston 21 can be, for example, a rod piston of the master brake cylinder 20. In addition to the adjustable piston 21 designed as a rod piston, the master brake cylinder 20 can optionally also have a floating piston.

[0038] The brake system also has a brake actuating element 22 with at least one driver braking force transmission component 24, the driver braking force F driver The at least one driver braking force transmission component can be transmitted to an adjustable piston 21 of a master brake cylinder 20. Brake actuating element 22 can include a brake pedal, for example. Driver braking force transmission component 24 can be, in particular, an input rod.

[0039] Furthermore, the brake system comprises a brake force booster 26 with at least one booster force transmission element 28. The booster force F provided by the brake force booster 26 support The at least one booster force transmission component can be transmitted to the adjustable piston 21 of the master brake cylinder 20. The brake force booster 26 can be, in particular, an electromechanical brake force booster with an electric motor (not shown). The booster force transmission component 28 can therefore be, for example, a booster piston. However, the constructability of the brake system is not limited to the use of an electromechanical brake force booster as brake force booster 26.

[0040] Sensor 30 is designed to provide sensor signal 10 already described above regarding the adjustment path of driver brake force transmission component 24 of brake actuating element 22 or of booster force transmission component 28 of brake booster 26 . Exemplary embodiments of sensor 30 will be described below.

[0041] In addition, a brake fluid reservoir 32 is connected to the master brake cylinder 20. Furthermore, at least one hydraulic pump 34 with a pump control 36 is hydraulically connected to the master brake cylinder 20. The master brake cylinder 20 is preferably designed with a foldable seal for sealing its at least one sniffer bore so that when there is a suction pressure in the master brake cylinder 20 brought about by the at least one pump 34, the seal of the master brake cylinder 20 folds over and thus becomes permeable to fluid. In this case, the at least one pump 34 can also suck brake fluid out of the brake fluid reservoir 32 through the master brake cylinder 20 after sealing its at least one sniffer bore.

[0042] The at least one pump 34 and its pump control 36 can be part of an ESP system (electronic stability program system) of the brake system. In addition, the brake system has at least one wheel brake cylinder 38, which is hydraulically connected to the delivery side of the at least one pump 34.

[0043] The brake system also has a control unit 40 which is Figures 2a to 2f In the embodiment of the present invention, it is, for example, the lower unit of the brake booster 26. The control unit 40 can therefore be referred to as a brake booster control unit. The control unit 40 can in particular be integrated in the housing of the brake booster. However, it is pointed out that the control unit 40 can only perform the functions described below if it is spaced apart / separate from the brake booster 26 at the brake system.

[0044] The control unit 40 is designed to detect or estimate, at least by means of the sensor signal 10 provided by the sensor 30 about the actuation path of the driver brake force transmission component 24 or the booster force transmission component 28, whether the adjustable piston 21 of the master brake cylinder 20 has been actuated from its starting position by a braking path s equal to a predetermined limit braking path s0 into the master brake cylinder 20. The term “actuation path” indicates the amount by which the driver brake force transmission component 24 or the booster force transmission component 26 is actuated by means of the driver brake force F driver or amplifier force F support The limit braking distance s0 can in particular refer to the maximum possible braking distance s, up to which the adjustable piston 21 can be adjusted into the master brake cylinder 20. In particular, the master brake cylinder 20 can be designed in such a way that the piston 21, which has been adjusted to the limit braking distance s0, hits a stop and is therefore not able to be adjusted further into the master brake cylinder 20.

[0045] If the control unit 40 recognizes or estimates that the braking stroke s of the adjustable piston 21 of the master brake cylinder 20 is equal to the predetermined limit braking stroke s0, the control unit 40 is designed to output at least one control signal 16 described above to a pump control mechanism 36 of at least one hydraulic pump 34, thereby activating the pump control mechanism in such a way that the brake fluid can be delivered from the brake fluid reservoir 32 to at least one wheel brake cylinder 38 by means of at least one hydraulic pump 34 driven by the pump control mechanism 36.

[0046] The control unit 40 can therefore ensure that even when the adjustable piston 21 of the master brake cylinder 20 hits a stop, a brake pressure increase in the at least one wheel brake cylinder 38 is still promoted when the piston 21 after the adjustment of the limit braking travel s0 can no longer be adjusted further into the master brake cylinder 20. The control unit 40 is therefore suitable for an MVR function (Master Cylinder Volume Replacement), thereby improving the safety standard of vehicles / motor vehicles equipped with the brake system.

[0047] The control unit 40 thus makes it superfluous to provide a "reserve volume" that can be pressed out of the master brake cylinder 20 by means of the adjustable piston 21. The master brake cylinder length of the master brake cylinder 20, that is to say the maximum extension length of the master brake cylinder 20 along the adjustment direction of its adjustable piston 21, can thus be shorter than in the prior art. The brake booster 26 can also be designed shorter along the adjustment direction of the adjustable piston 21, so that the brake booster 26 can be installed more easily on the vehicle / motor vehicle, without the brake booster 26 having to extend (far) into the vehicle passenger compartment of the vehicle / motor vehicle. This helps to reduce the risk of injury to the driver of the vehicle / motor vehicle in the event of an accident involving the driver's vehicle / motor vehicle.

[0048] Control unit 40 is preferably designed to detect or estimate whether braking travel s of adjustable piston 21 of master brake cylinder 20 is equal to a predetermined limit braking travel s0, at least by means of sensor signal 10 provided by a rotation sensor or motor current sensor of an electric motor of brake booster 26 designed as an electromechanical brake booster, about the adjustment travel of booster force transmission component 38. Thus, a rotation sensor or motor current sensor of an electric motor can also be used as sensor 30. Since electric motors are usually already equipped with such sensor types, control unit 40 can be used without an expansion of the sensor system of the brake system.

[0049] The control unit 40 can optionally also be designed to detect or estimate whether the braking travel s of the adjustable piston 21 of the master brake cylinder 20 is equal to the predetermined limit braking travel s0, taking into account the additional sensor signal 12 already mentioned above. The additional sensor signal 12 can be, for example, a rod travel signal of a rod travel sensor of the driver's brake force transmission component 24 designed as an input rod (regarding the adjustment travel of the input rod) or a travel difference signal of a travel difference sensor (regarding the travel difference Δ between the adjustment travel of the input rod and the adjustment travel of the booster force transmission component 28 designed as a booster piston). Thus, already known sensor types can cooperate with the control unit 40.

[0050] As an advantageous development, if control unit 40 detects or estimates that braking travel s of adjustable piston 21 of master brake cylinder 20 is equal to predetermined limit braking travel s0, control unit 40 can additionally be designed to determine a setpoint variable regarding a setpoint volume flow to be delivered from brake fluid reservoir 32 to at least one wheel brake cylinder 38 at least by means of provided sensor signal 10 and / or further sensor signal 12, and to activate pump control 36 by means of at least one control signal 16 in such a way that an actual volume flow Q corresponding to the setpoint variable can be delivered from / from brake fluid reservoir 32 to at least one wheel brake cylinder 38 by means of at least one hydraulic pump 34 controlled by pump control 36. The delivery of brake fluid 34 from brake fluid reservoir 32 to at least one wheel brake cylinder 38 can thus be adapted to a braking request predefined by the driver.

[0051] Control unit 40 may also be designed to implement further functions. Control unit 40 may, for example, be additionally designed to determine a desired booster variable for a desired booster force to be implemented by means of brake booster 26 at least with the aid of provided sensor signal 10 and / or further sensor signal 12, and to control power booster 26 with the aid of at least one of the above-mentioned booster control signals 16 in such a way that brake booster 16 provides a booster force F corresponding to the desired booster variable via booster force transmission element 28. support Control unit 40 can therefore also easily perform the functions of a conventional brake booster control unit.

[0052] As a further advantageous further development, the control unit 40 can be additionally designed to determine the desired booster variable according to a first predetermined characteristic line if the control unit 40 detects or estimates that the braking travel s of the adjustable piston 21 of the master brake cylinder 20 is below a predetermined limit braking travel s0, and can be additionally designed to determine the desired booster variable according to a second predetermined characteristic line if the control unit 40 detects or estimates that the braking travel s of the adjustable piston 21 of the master brake cylinder 20 is equal to the predetermined limit braking travel s0. The first and second characteristic lines can be, for example, functions that assign a specific desired booster force to the adjustment travel of the driver brake force transmission component 24 or a desired adjustment travel of the booster force transmission component 28 corresponding to the desired booster force or a corresponding desired travel difference between the adjustment travel of the input rod and the adjustment travel of the valve body. The first and second characteristic lines are preferably determined as functions in such a way that the second characteristic line provides a lower desired booster force or a smaller desired adjustment travel of the booster force transmission component 28 or a correspondingly adapted desired travel difference to the adjustment travel of the driver brake force transmission component 24 than the first characteristic line. The first characteristic curve can therefore be referred to as a standard characteristic curve, while the second characteristic curve can be interpreted as a force balance characteristic curve. The characteristic curve transformation described here can be used to adjust the brake actuation feeling / pedal feeling of the driver who actuates the brake actuating element 22 so that the driver does not / hardly perceives the reaction of the adjustable piston 21 of the master brake cylinder 20 to adjust the predetermined limit braking travel s0. The booster force F of the brake force booster 26 support In particular, with the aid of the characteristic line transformation described here, when it is recognized or estimated that the braking stroke s of the adjustable piston 21 of the master brake cylinder 20 is equal to a predetermined limit braking stroke s0, the driver is not encouraged to try to push away a stop that opposes the action of the adjustable piston 21, because the "behavior of the brake operating element 22" felt by the driver here would stimulate the driver.

[0053] With the help of Figures 2b to 2f The coordinate system of once again schematically illustrates the working mode of the control unit 40:

[0054] exist Figures 2b to 2f In the coordinate system, the horizontal axis is the time axis t. Figure 2b The ordinate of the coordinate system indicates the braking travel s of adjustable piston 21 of master brake cylinder 20 . Figure 2c The ordinate of the coordinate system of Δ indicates the travel difference Δ. The actual volume flow Q caused by the at least one hydraulic pump 34 from the brake fluid reservoir 32 to the at least one wheel brake cylinder 38 is Figure 2d The ordinate of the coordinate system is shown. Figure 2e and 2fThe ordinate of the coordinate system represents the brake pressure p present in at least one wheel brake cylinder 38. 38 and the master brake cylinder internal pressure p present in the master brake cylinder 20 20 .

[0055] From time t0, the driver operates his brake operating element 32. However, until time t3, the braking stroke s of the adjustable piston 21 of the master brake cylinder 20 still remains below the predetermined limit braking stroke s0. From time t3, the braking stroke s of the adjustable piston 21 of the master brake cylinder 20 is equal to the predetermined limit braking stroke s0, and therefore the at least one hydraulic pump 34 is activated from time t3. From time t3, the at least one hydraulic pump 34 generates a suction pressure in the master brake cylinder 20, so that the master brake cylinder internal pressure p 20 At least one hydraulic pump 34 simultaneously delivers brake fluid from the brake fluid reservoir 32 to at least one wheel brake cylinder 38, so that the brake pressure p present in at least one wheel brake cylinder 38 is 38 Ascend. Figure 2d As can be seen from the coordinate system of , the actual volume flow promoted by at least one hydraulic pump 34 can also be matched to the driver's braking intention. At the same time, the travel difference Δ can be adjusted in this way so that the driver still has a brake actuation feeling / pedal feeling that meets the standard.

[0056] From time t4 onwards, the braking travel s of the adjustable piston 21 of the master brake cylinder 20 is again below the predetermined limit braking travel s0. The at least one hydraulic pump 34 is therefore again in its inactive mode from time t4 onwards.

[0057] It should be noted that the usability of the control unit 40 / the brake system configured with the control unit is not limited to a specific vehicle type / motor vehicle type. The communication between the control unit 40, the sensor 30, the pump control 36 and possibly the brake booster 16 can take place via a network, for example via a CAN (Controller Area Network) or via Flexray.

Claims

1. A control unit (40) for a braking system of a vehicle, wherein: The control unit (40) is designed to detect or estimate, at least by means of a sensor signal (10) provided by a sensor (30) regarding an adjustment travel of a driver's brake force transmission component (24) of a brake operating element (22) of the brake system or a booster force transmission component (28) of a brake force booster (26) of the brake system, whether an adjustable piston (21) of a master brake cylinder (20) of the brake system has been adjusted from its starting position by a braking travel (s) equal to a predetermined limit braking travel (s0) into the master brake cylinder (20), and to output at least one control signal (14) to a pump control (36) of at least one hydraulic pump (34) of the brake system, wherein the pump control (36) can be activated by means of the at least one control signal (14) in such a way that brake fluid can be delivered from a brake fluid reservoir (32) of the brake system to at least one wheel brake cylinder (38) of the brake system by means of at least one hydraulic pump (34) driven by the pump control (36).

2. The control unit (40) according to claim 1, wherein: The control unit (40) is designed to detect or evaluate whether the braking travel (s) of the adjustable piston (21) of the master brake cylinder (20) is equal to the predetermined limit braking travel (s0), at least with the help of a sensor signal (10) about the adjustment travel of the amplifier force transmission component (28) provided by a rotation sensor or a motor current sensor of an electric motor of a brake booster (26) configured as an electromechanical brake booster.

3. A control unit (40) according to claim 1 or 2, wherein: The control unit (40) is designed to recognize or estimate whether the braking travel (s) of the adjustable piston (21) of the master brake cylinder (20) is equal to the predetermined limit braking travel (s0) by additionally taking into account a travel difference signal of a travel difference sensor of the brake booster (26) which is configured as an electromechanical brake booster.

4. A control unit (40) according to claim 1 or 2, wherein: The control unit (40) is designed to recognize or evaluate whether a braking travel (s) of an adjustable piston (21) of the master brake cylinder (20) is equal to a predetermined limit braking travel (s0) by additionally taking into account a rod travel signal of a rod travel sensor at the driver braking force transmission component (24) configured as an input rod.

5. The control unit (40) according to claim 3, wherein: As soon as the control unit (40) detects or estimates that the braking travel (s) of the adjustable piston (21) of the master brake cylinder (20) is equal to the predetermined limit braking travel (s0), the control unit (40) is additionally designed to: determine a setpoint variable regarding a setpoint volume flow to be delivered from the brake fluid reservoir (32) to the at least one wheel brake cylinder (38) at least by means of the provided sensor signal (10), the travel difference signal and / or the rod travel signal, and activate the pump control device (36) by means of the at least one control signal (14) in such a way that an actual volume flow (Q) corresponding to the setpoint variable can be delivered from the brake fluid reservoir (32) to the at least one wheel brake cylinder (38) by means of at least one hydraulic pump (34) driven by the pump control device (36).

6. The control unit (40) according to claim 3, wherein: The control unit (40) is additionally designed to determine a setpoint booster variable for a setpoint booster force to be implemented by means of the brake booster (26) at least by means of the provided sensor signal (10), the travel difference signal and / or the rod travel signal, and to control the brake booster (26) by means of at least one booster control signal (16) in such a way that the brake booster (26) provides a booster force (F) corresponding to the setpoint booster variable via the booster force transmission element (28). support ).

7. The control unit (40) according to claim 6, wherein: The control unit (40) is additionally designed to: determine the setpoint amplifier variable according to a predetermined first characteristic line if the control unit (40) recognizes or estimates that the braking stroke (s) of the adjustable piston (21) of the master brake cylinder (20) is lower than the predetermined limit braking stroke (s0), and determine the setpoint amplifier variable according to a predetermined second characteristic line if the control unit (40) recognizes or estimates that the braking stroke (s) of the adjustable piston (21) of the master brake cylinder (20) is equal to the predetermined limit braking stroke (s0).

8. A brake booster (26) for a vehicle brake system having a control unit (40) according to any one of claims 1 to 7.

9. Braking systems for vehicles, having: A control unit (40) according to any one of claims 1 to 7; A master brake cylinder (20) having at least the adjustable piston (21); A brake operating element (22) having at least the driver braking force transmission component (24), a driver braking force (F driver ) can be transmitted to the adjustable piston (21) of the master brake cylinder (20) through the driver's brake force transmission component; A brake force booster (26) having at least the booster force transmission component (28), a booster force (F support ) can be transmitted to the adjustable piston (21) of the master brake cylinder (20) through the amplifier force transmission component; A sensor (30) is designed to supply a sensor signal (10) about an adjustment travel of a driver brake force transmission component (24) of a brake actuating element (22) or a booster force transmission component (28) of a brake force booster (26) to a control unit (40); A brake fluid reservoir (32) connected to the master brake cylinder (20); at least one hydraulic pump (34) connected to the master brake cylinder (20), the hydraulic pump having its pump control mechanism (36); and At least one wheel brake cylinder (38) is connected to the delivery side of at least one hydraulic pump (34).

10. A method for operating a braking system of a vehicle, comprising the steps of: At least by means of a sensor signal (10) provided by a sensor (30) regarding the adjustment travel of a driver's brake force transmission component (24) of a brake operating element (22) of the brake system or a booster force transmission component (28) of a brake force booster (26) of the brake system, it is checked or estimated whether an adjustable piston (21) of a master brake cylinder (20) of the brake system has been adjusted from its starting position to a braking travel (s) equal to a predetermined limit braking travel (s0) into the master brake cylinder (20); and If it is detected or estimated that the braking travel (s) of the adjustable piston (21) of the master brake cylinder (20) is equal to the predetermined limit braking travel (s0), a pump control device (36) of at least one hydraulic pump (34) of the brake system is activated in such a way that brake fluid is delivered from a brake fluid reservoir (32) of the brake system to at least one wheel brake cylinder (38) of the brake system by means of at least one hydraulic pump (34) driven by the pump control device (36).

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