DE102020211993A1 - Control device and method for operating an electromechanical brake booster of a brake system of a vehicle - Google Patents

Abstract

The invention relates to a method and a control device for operating an electromechanical brake booster (10) of a braking system of a vehicle by specifying a target differential travel between a driver brake force transmission component and a motor force transmission component that can be adjusted by means of a motor force of the electromechanical brake booster (10) and operating the electromechanical one brake booster (10), insofar as the same brake pressure build-up is effected to a brake pressure in at least one master brake cylinder (12), connected front wheel wheel brake cylinders (14) and connected rear wheel wheel brake cylinders (16) of the brake system by means of the driver's brake force and the motor force corresponds to the driver braking force according to a predetermined standard driver braking force-brake pressure relation of the brake system, a predetermined standard value is set as the target differential travel, and where, if by means of the driver braking force t and the motor force in the master brake cylinder (12), at least one of the front wheel wheel brake cylinders (14) and/or at least one of the rear wheel wheel brake cylinders (16), a brake pressure build-up is effected via the brake pressure corresponding to the driver brake force according to the specified standard driver brake force-brake pressure relationship , the target differential distance is set differently from the standard value.

Description

The invention relates to a method for operating an electromechanical brake booster of a brake system of a vehicle. The invention also relates to a method for operating a vehicle brake system equipped with an electromechanical brake booster. Furthermore, the invention relates to a control device for at least one electromechanical brake booster of a brake system of a vehicle and a brake system for a vehicle.

State of the art

1a until 1c show coordinate systems for explaining a conventional procedure for operating a brake system of a vehicle equipped with an electromechanical brake booster.

When using the 1a until 1c schematically reproduced conventional procedure, a driver of the vehicle requests a vehicle deceleration of his vehicle not equal to zero from a time t1 by means of his driver braking force exerted on a brake actuation element of the vehicle. The requested vehicle deceleration should preferably be brought about by means of a recuperative operation of at least one electric motor that can be used to brake the vehicle. However, when using the 1a until 1c reproduced example assumed at the time t1 that the requested vehicle deceleration is at least momentarily not effected by means of the recuperative operation of the at least one electric motor. Therefore, at time t1 the requested vehicle deceleration is effected by means of a brake pressure build-up in the front wheel wheel brake cylinders to a front wheel brake pressure p _front unequal to zero, while a rear wheel brake pressure p _rear present in the rear wheel wheel brake cylinders is increased to at most a storage chamber response pressure of at least one den Wheel brake cylinders downstream storage chamber of the braking system is limited. This is in the coordinate system of 1a reproduced, the abscissa of which is a time axis t, while pressure values p and braking torque values M are reproduced by means of its ordinate. In the coordinate system of 1a a brake pressure p _standard is also drawn in, which would be present in the front wheel wheel brake cylinders and in the rear wheel wheel brake cylinders if the requested vehicle deceleration was achieved by means of the same pressure build-up in the front wheel wheel brake cylinders and in the rear wheel wheel brake cylinders (P _front = p _rear ). a predetermined standard driver brake force brake pressure relation of the brake system would be effected.

At a time t2, the driver overcomes a in the coordinate system 1a schematically reproduced jump-in area JI and therefore now feels a pedal counterforce F _pedal , which counteracts its further actuation of the brake actuation element. While the abscissa of the coordinate system of the 1b is a time axis t is determined by the ordinate of the coordinate system of 1b the pedal counterforce F _pedal is reproduced.

Also the abscissa of the coordinate system of the 1c is a time axis t, while by means of the ordinate of the coordinate system of 1c a target differential travel Δ specified for operating the electromechanical brake booster is displayed. Target differential travel Δ is understood to mean a differential travel to be set between a driver brake force transmission component and a motor force transmission component for transmitting a motor force of the electromechanical brake booster. With the same pressure build-up in the front wheel wheel brake cylinders and in the rear wheel wheel brake cylinders (p _front = p _rear ) according to the specified standard driver brake force-brake pressure relation of the brake system, the target differential travel Δ (almost) always has a specified standard value Δ _standard of zero set, which is why in this case the pedal counterforce F _pedal corresponds to a standard driver brake force pedal counterforce relation f _pedal specified for the brake system, which is shown in 1b is drawn.

When using the 1a until 1c reproduced conventional procedure, the target differential path Δ is also set from time t1 to the specified standard value Δ _standard of zero. As in the coordinate system of 1b however, as can be seen, this conventional procedure for operating the electromechanical brake booster at a front wheel brake pressure p _front above the brake pressure p _standard results in a deviation of the pedal counterforce F _pedal from the standard driver brake force/pedal counterforce relation f _pedal .

In the case of the 1a until 1c In the example shown, the at least one electric motor can be operated in its recuperative mode from a point in time t3 in such a way that the vehicle can be braked by means of the at least one electric motor. Therefore, starting at time t3, the generator braking torque M _gen produced by the at least one electric motor is increased, while at the same time the front-wheel braking pressure p _front is correspondingly reduced. From a time point t4, the front wheel brake pressure p _front is less than or equal to the brake pressure p _standard , which is why when using the 1a until 1c reproduced conventional procedure of the target differential path Δ from the time t4 deviating from the standard value Δ _standard is set. From a point in time t5, the front wheel brake pressure p _front is limited to a maximum of the accumulator chamber response pressure.

Disclosure of Invention

The invention creates a method for operating an electromechanical brake booster of a brake system of a vehicle with the features of claim 1, a method for operating a brake system of a vehicle equipped with an electromechanical brake booster with the features of claim 4, a control device for at least one electromechanical brake booster of a brake system of a vehicle having the features of claim 7 and a braking system for a vehicle having the features of claim 10.

Advantages of the Invention

The present invention provides advantageous possibilities for improving a brake operating feel/pedal feel of a driver operating a brake operating member/brake pedal of his vehicle. In particular, the present invention contributes to improving the feel of the brake actuation/pedal feel in such situations in which a brake pressure build-up via a brake pressure in a master brake cylinder, at least one of the front wheel brake cylinders and/or at least one of the rear wheel brake cylinders of the respective brake system is effected / is. Since the operating mode of the brake system described in the previous sentence is well suited for braking the vehicle while maintaining the possibility of rapid brake pressure reduction in at least one of the front wheel wheel brake cylinders and/or at least one of the rear wheel wheel brake cylinders, so that at least one in its recuperative operation for Since an electric motor suitable for braking the vehicle can be used immediately afterwards, the present invention also contributes to increasing the braking comfort of the vehicle using the invention.

In an advantageous embodiment of the method, if it is estimated or determined that the driver braking force and the engine force in at least one of the front wheel wheel brake cylinders cause a brake pressure build-up above the braking pressure corresponding to the driver braking force according to the specified standard driver braking force-brake pressure relation, while in at least one of the rear wheel wheel brake cylinders, the brake pressure build-up is limited to a maximum of a storage chamber response pressure of at least one storage chamber of the brake system, the target differential travel is specified taking into account a sensor variable corresponding to the driver's braking force and a first characteristic curve and deviating from the standard value. As becomes clear from the following description, it can be ensured in this way that the driver, even in an operating mode of the brake system which is well suited for braking the vehicle while maintaining a possibility of rapid brake pressure reduction in at least one of the front wheel brake cylinders, is a standard brake actuation/pedal feel.

As an advantageous further development, if it is estimated or determined that, despite the driver braking force being unequal to zero, the brake pressure build-up in at least one of the front wheel wheel brake cylinders and in at least one of the rear wheel wheel brake cylinders is limited to a maximum of the accumulator chamber response pressure, the target differential travel, taking into account the sensor variable corresponding to the driver braking force and a second characteristic curve deviating from the first characteristic curve and/or deviating from the standard value. This means that even in an operating mode of the brake system in which the brake pressure build-up in at least one of the front wheel wheel brake cylinders and in at least one of the rear wheel wheel brake cylinders is limited to a maximum of the storage chamber response pressure, a standard brake actuation feel/pedal feel can be guaranteed for the driver.

Also a corresponding method for operating a brake system of a vehicle equipped with an electromechanical brake booster, wherein, while a driver brake force is transmitted via at least one driver brake force transmission component to at least one adjustable piston of a master brake cylinder of the brake system with connected front wheel wheel brake cylinders and connected rear wheel wheel brake cylinders of the brake system , the electromechanical brake booster, the engine power of which is transmitted via at least one adjustable engine power transmission component to the at least one adjustable piston of the master brake cylinder, is operated according to a corresponding method, creates the advantages described above.

As an advantageous further development of the method, a request can be made for a means of the driver's braking force terte vehicle deceleration can be determined or estimated as to whether the requested vehicle deceleration can be effected and/or is effected by means of recuperative operation of at least one electric motor that can be used to brake the vehicle. In this case, at least if it is determined or estimated that the requested vehicle deceleration is brought about by means of the recuperative operation of the at least one electric motor, at least one valve of the brake system is preferably switched in such a way that, despite the driver braking force not being equal to zero, the brake pressure builds up in at least one of the front wheels -Wheel brake cylinder and in at least one of the rear wheel wheel brake cylinders is limited to a maximum of the storage chamber response pressure, while if it is ruled out that the requested vehicle deceleration can be effected by means of the recuperative operation of the at least one electric motor, the at least one valve is at least sometimes switched in such a way, that by means of the driver's brake force and the engine power at least in the master brake cylinder, the front wheel brake cylinders and the rear wheel brake cylinders of the same brake pressure build-up on the driver's brake force according to the specified standard driver brake force aft brake pressure relation of the brake system corresponding brake pressure is effected. The embodiment of the method described here ensures that the vehicle is not overbraked during the recuperative operation of the at least one electric motor, but can still be reliably brought to a standstill whenever the at least one electric motor cannot be used to brake the vehicle.

In particular, if it is determined or estimated that the requested vehicle deceleration can probably be effected by means of the recuperative operation of the at least one electric motor after waiting at most a predetermined maximum waiting time, the at least one valve can be switched in such a way that the brake pressure builds up in at least one of the front wheel wheel brake cylinders is effected via the brake pressure corresponding to the driver brake force according to the predetermined standard driver brake force-brake pressure relation, while in at least one of the rear wheel brake cylinders the brake pressure build-up is limited to a maximum of the accumulator chamber response pressure. At the same time, it can be ensured that the driver continues to have a standard brake operation feel/pedal feel.

Likewise, a corresponding control device for at least one electromechanical brake booster of a braking system of a vehicle also creates the advantages described above, with the control device being able to be developed in accordance with the above-explained embodiments of methods.

Furthermore, the advantages explained above are also guaranteed in a brake system for a vehicle that is equipped with a corresponding control device, the electromechanical brake booster, whose motor can be controlled by the control device, with the electromechanical brake booster being upstream of a master brake cylinder of the brake system in such a way that, while a driver braking force can be transmitted via at least one driver braking force transmission component to at least one adjustable piston of the master brake cylinder, a motor force of the motor of the electromechanical brake booster can be transmitted via at least one adjustable motor force transmission component to the at least one adjustable piston of the master brake cylinder, front wheel wheel brake cylinders connected to the master brake cylinder and rear wheel brake cylinders connected to the master brake cylinder.

character list

• 1a bis 1c Koordinatensysteme zum Erläutern einer herkömmlichen Vorgehensweise zum Betreiben eines mit einem elektromechanischen Bremskraftverstärker ausgestatteten Bremssystems eines Fahrzeugs;
• 2 ein Flussdiagramm zum Erläutern einer Ausführungsform des Verfahrens zum Betreiben eines elektromechanischen Bremskraftverstärkers eines Bremssystems eines Fahrzeugs;
• 3a bis 3c Koordinatensysteme zum Erläutern einer Ausführungsform des Verfahrens zum Betreiben eines mit einem elektromechanischen Bremskraftverstärker ausgestatteten Bremssystems eines Fahrzeugs; und
• 4 eine schematische Darstellung einer Steuervorrichtung für zumindest einen elektromechanischen Bremskraftverstärker eines Bremssystems eines Fahrzeugs, bzw. des damit ausgestatteten Bremssystems.

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

• 1a until 1c Coordinate systems for explaining a conventional procedure for operating a vehicle brake system equipped with an electromechanical brake booster;
• 2 a flowchart for explaining an embodiment of the method for operating an electromechanical brake booster of a brake system of a vehicle;
• 3a until 3c Coordinate systems for explaining an embodiment of the method for operating a brake system of a vehicle equipped with an electromechanical brake booster; and
• 4 a schematic representation of a control device for at least one electromechanical brake booster of a brake system of a vehicle, or the brake system equipped therewith.

Embodiments of the invention

2 shows a flow chart for explaining an embodiment of the method for operating an electromechanical brake booster of a brake system of a vehicle.

The electromechanical brake booster is preferably to be understood as a type of brake booster which is upstream of a master brake cylinder of the respective brake system in such a way that, while a driver braking force is transmitted to at least one adjustable piston of the master brake cylinder via at least one adjustable driver brake force transmission component, a motor force of a motor of the electromechanical brake booster is transmitted is transmitted via at least one adjustable engine power transmission component to the at least one adjustable piston of the brake master cylinder. The driver brake force transmission component can be, for example, an input rod of the electromechanical brake booster. The driver braking force is preferably understood to mean a driver braking force exerted by a driver of the respective vehicle by actuating a brake activation element. The brake actuation element can be a brake pedal, for example. In particular, a valve body of the electromechanical brake booster can be used as the motor force transmission component. It is expressly pointed out that the ability to carry out the method described below is not limited to any special brake system type of the brake system equipped with the electromechanical brake booster. Likewise, the ability to carry out the method described below is not limited to any particular vehicle type/motor vehicle type of the vehicle/motor vehicle equipped with the respective braking system.

In a method step S1 of the method, a target differential travel is defined between the driver braking force transmission component that can be adjusted by means of the transmitted driver braking force and the engine force transmission component that can be adjusted by means of the engine force. In a further method step S2, the motor of the electromechanical brake booster is operated in such a way that a differential path between the driver brake force transmission component and the motor force transmission component that corresponds to the specified setpoint differential path is set. In this way, the motor force of the motor of the electromechanical brake booster transmitted to the at least one adjustable piston of the master brake cylinder is "adapted" to the driver's braking force, and thus also to a vehicle deceleration of his vehicle requested by the driver using the driver's braking force.

When method step S1 is executed, it is also estimated or determined whether the same brake pressure build-up to a (common) brake pressure is caused by the driver braking force and the engine power at least in a master brake cylinder, connected front wheel wheel brake cylinders and connected rear wheel wheel brake cylinders of the brake system, which is the driver braking force corresponds to a predetermined standard driver brake force brake pressure relation of the brake system. If it is estimated or determined that the same brake pressure build-up is effected at least in the master brake cylinder, the front wheel wheel brake cylinders and the rear wheel wheel brake cylinders to the brake pressure corresponding to the driver brake force according to the specified standard driver brake force-brake pressure relation using the driver brake force and the engine power, a predetermined Default value set as target differential distance. As already explained above, executing method steps S1 and S2 in this case causes the driver to feel a pedal counterforce counteracting his actuation of the brake pedal, which corresponds to a standard driver braking force-pedal counterforce relation specified for the brake system. The driver operating the brake operating member thus has a standard and comfortable brake operating feel/pedal feel. The default value specified for the target differential path can be zero, for example.

However, if it is estimated or determined when executing method step S1 that by means of the driver braking force and the engine force in the master brake cylinder, at least one of the front wheel wheel brake cylinders and/or at least one of the rear wheel wheel brake cylinders, a brake pressure build-up above that of the driver braking force according to the specified standard Brake pressure corresponding to the driver's braking force-brake pressure relation is effected, the target differential travel is set differently from the standard value. By defining the target differential travel deviating from the standard value, the pedal counterforce can, despite the brake pressure buildup in the master brake cylinder, at least one of the front wheel wheel brake cylinders and/or at least one of the rear wheel wheel brake cylinders, exceed the brake pressure corresponding to the driver brake force according to the specified standard driver brake force-brake pressure relation be "set" equal to the specified standard driver brake force pedal counterforce relation. In this way it can be ensured that the driver actuating the brake actuating element continues to have the standard and pleasant brake actuating feel/pedal feel.

For example, due to throttling effects on at least one valve in the brake system, when the volume of brake fluid moves into at least one storage chamber of the brake circuit in the master brake cylinder, at least one of the front wheel brake cylinders and/or at least one of the rear wheel brake cylinders which lead to a transitional brake pressure increase above the brake pressure corresponding to the driver brake force according to the specified standard driver brake force/brake pressure relation. By means of the method described here, however, it can be ensured that the driver actuating the brake actuating element continues to have the standard and pleasant brake actuating feel/pedal feel. Another situation in which the method described here is advantageous is explained in more detail below.

Preferably, when brake pressure builds up in the master brake cylinder, at least one of the front wheel wheel brake cylinders and/or at least one of the rear wheel wheel brake cylinders, the target differential travel is set so that it deviates from the standard value via the brake pressure corresponding to the driver brake force according to the predefined standard driver brake force/brake pressure relationship by means of an “increase” in the current motor force compared to a motor force that is caused when the target differential travel is set to be equal to the standard value, the pedal counterforce is “set” to be equal to the specified standard driver brake force-pedal counterforce relation. If the target differential travel is defined as a difference between an adjustment travel of the driver brake force transmission component minus an adjustment travel of the engine power transmission component and if the standard value is equal to zero, then when brake pressure builds up in the master brake cylinder, at least one of the front wheel Wheel brake cylinder and/or at least one of the rear wheel wheel brake cylinders can be set to a value greater than zero via the brake pressure corresponding to the driver brake force according to the predetermined standard driver brake force/brake pressure relation.

As an advantageous development, if it is estimated or determined that the driver braking force and the motor force are used to cause a brake pressure build-up in at least one of the front wheel wheel brake cylinders above the braking pressure corresponding to the driver braking force according to the specified standard driver braking force-brake pressure relationship, while in at least one of the rear wheels -Wheel brake cylinder, the build-up of brake pressure is/is limited to a maximum of a storage chamber response pressure of at least one storage chamber of the brake system, the target differential travel, taking into account a sensor size corresponding to the driver's braking force and a first characteristic curve, and deviating from the standard value. In this way it can be ensured that despite the brake pressure build-up in at least one of the front wheel wheel brake cylinders via the brake pressure corresponding to the driver brake force according to the specified standard driver brake force-brake pressure relationship, the driver still has the standard and pleasant brake actuation/pedal feel. Likewise, if it is estimated or determined that, despite the driver braking force not being equal to zero, the brake pressure build-up in at least one of the front wheel wheel brake cylinders and in at least one of the rear wheel wheel brake cylinders is/is limited to a maximum of the accumulator chamber response pressure, the target differential travel, taking into account the sensor variable corresponding to the driver braking force and a second characteristic curve deviating from the first characteristic curve and/or deviating from the standard value. The advantages of this development are explained in more detail with reference to the next figures.

3a until 3c show coordinate systems for explaining an embodiment of the method for operating a brake system of a vehicle equipped with an electromechanical brake booster.

The method described below can be carried out for any brake system in which, while a driver braking force is being transmitted via at least one adjustable driver braking force transmission component to at least one adjustable piston of a master brake cylinder of the brake system with connected front wheel wheel brake cylinders and connected rear wheel wheel brake cylinders, the electromechanical brake booster is activated in such a way upstream of the master brake cylinder is that its engine power is transmitted via at least one adjustable engine power transmission component to the at least one adjustable piston of the master brake cylinder. In particular, the brake system can have two brake circuits with an X brake circuit distribution. Examples of the driver braking force transmission component and the engine force transmission component have already been mentioned above. In addition, the ability to carry out the method described below is not limited to any special vehicle type/motor vehicle type of the respective brake system.

At one by means of 3a until 3c reproduced example, a driver requests a vehicle deceleration of the vehicle not equal to zero from a point in time t1 by means of his driver braking force exerted on a brake actuation element of his vehicle. The brake actuation element can be a brake pedal, for example. The requested vehicle deceleration is preferably brought about by means of recuperative operation of at least one electric motor that can be used to brake the vehicle, as a result of which kinetic energy of the vehicle is converted into electrical energy that can be stored on at least one energy storage unit of the vehicle can, in order to reduce energy consumption and possibly also pollutant emissions of the vehicle. It is therefore determined or estimated at time t1 for the vehicle deceleration requested by the driver braking force whether the requested vehicle deceleration can be effected and/or is being effected by means of the recuperative operation of the at least one electric motor. This is advantageous because when the at least one energy storage unit of the vehicle is fully charged or when the vehicle speed of the vehicle is below a predefined minimum recuperation speed, the recuperative operation of the at least one electric motor cannot usually be carried out.

At least if it is ruled out that the requested vehicle deceleration can be brought about by means of the recuperative operation of the at least one electric motor, at least one valve of the brake system is at least sometimes switched in such a way that the same brake pressure build-up in the master brake cylinder, the front wheel wheel brake cylinders and the rear wheel wheel brake cylinders to a brake pressure p _standard corresponding to the driver brake force according to a predetermined standard driver brake force-brake pressure relation of the brake system. In the coordinate system of 3a the abscissa is a time axis t, while the ordinate represents pressure values p and braking torque values M. The brake pressure p _standard corresponding to the driver brake force according to the predetermined standard driver brake force-brake pressure relation of the brake system is in the coordinate system of 3a drawn. If the brake pressure p _standard in the front wheel wheel brake cylinders and in the rear wheel wheel brake cylinders corresponds to the driver brake force according to the specified standard driver brake force-brake pressure relation, a target differential path Δ between the driver brake force transmission component and the motor force transmission component is set to a standard value Δ _standard fixed. As already explained above, this brings about a standard and pleasant brake actuation feeling for the driver according to a predefined standard driver brake force/pedal counterforce relation f _pedal of the brake system. The standard value Δ _standard can be equal to zero, for example.

However, the brake pressure build-up to the brake pressure p _standard caused in all front wheel wheel brake cylinders and rear wheel wheel brake cylinders of the brake system has the disadvantage that no rapid brake pressure reduction to at most one storage chamber response pressure of at least one storage chamber of the brake system by moving brake fluid into the at least one more storage chamber is possible. Therefore, in the method described here, if it is determined or estimated that the requested vehicle deceleration can probably be effected after waiting at most a predetermined maximum waiting time by means of the recuperative operation of the at least one electric motor, at least one valve is switched in such a way that in the front wheel wheel brake cylinders the brake pressure build-up is effected via the brake pressure p _standard corresponding to the driver brake force according to the specified standard driver brake force-brake pressure relationship of the brake system, while the brake pressure build-up in the rear wheel wheel brake cylinders is/is limited to a maximum of the accumulator chamber response pressure.

In the example of 3a until 3c it is determined or estimated at time t1 that the requested vehicle deceleration can probably be effected by means of the recuperative operation of the at least one electric motor after waiting at most the specified maximum waiting time. For example, it can be recognized that due to the characteristics of the at least one electric motor and due to a rapid change from the gas pedal to the brake pedal, the recuperative operation of the at least one electric motor is merely delayed. It can also be recognized that the at least one electric motor is decoupled from a gear shift of the vehicle and can therefore temporarily not be used for recuperative braking of the vehicle. Therefore, from time t1, a front-wheel brake pressure p _front in the front-wheel wheel brake cylinders is increased so much above the brake pressure p _standard corresponding to the driver brake force according to the specified standard driver brake force-brake pressure relationship that the vehicle deceleration requested by the driver using his driver brake force is reliably effected. At the same time, from time t1, a rear wheel brake pressure p _rear in the rear wheel wheel brake cylinders is limited to a maximum of the storage chamber response pressure, so that by opening at least one wheel inlet valve upstream of the rear wheel wheel brake cylinders, the front wheel brake pressure p _front in the front wheel wheel brake cylinders is reduced can be quickly reduced to a maximum of the accumulator chamber response pressure.

wobei F_hydraulik eine dem Hineinverstellen des mindestens einen verstellbaren Kolbens des Hauptbremszylinders entgegenwirkende Druckkraft, F_spring eine Federkraft mindestens einer Feder des elektromechanischen Bremskraftverstärkers und/oder des Hauptbremszylinders und F_motor die Motorkraft des Motors des elektromechanischen Bremskraftverstärkers sind.From a time t2, the driver overcomes a in the coordinate system 3a schematically reproduced jump-in area JI. From time t2, there is therefore the theoretical possibility that the driver will feel a counteracting pedal force F _pedal counteracting his actuation of the brake pedal. The actuation of the brake pedal counteracting pedal counterforce F _pedal is in the coordinate system 3b marked, whose abscissa is a time axis t. The pedal counterforce F _pedal results from equation (Eq. 1) with: $${\text{f}}_{\text{pedal}}={\text{f}}_{\text{hydraulics}}+{\text{f}}_{\text{jump}}-{\text{f}}_{\text{engine}},$$

where F _hydraulic is a pressure force counteracting the inward movement of the at least one adjustable piston of the master brake cylinder, F _spring is a spring force of at least one spring of the electromechanical brake booster and/or the master brake cylinder and F _motor is the motor force of the motor of the electromechanical brake booster.

In the method described here, the electromechanical brake booster is activated according to in 2 Procedure shown schematically operated. This is by means of the coordinate system of 3c reproduced schematically, the abscissa of which is a time axis t, while its ordinate indicates the target differential travel Δ between the driver braking force transmission component and the motor force transmission component that is specified for operating the electromechanical brake booster. As in 3c is recognizable, from time t1 onwards the target differential travel Δ is defined taking into account the driver braking force/a sensor variable corresponding to it and a first characteristic curve k ₁ and deviating from the standard value Δ _standard . In particular, the setpoint differential travel Δ, defined as a difference in an adjustment path of the driver brake force transmission component minus an adjustment path of the motor force transmission component, while the standard value Δ _standard is equal to zero, is set to a value greater than zero from time t1. When the motor of the electromechanical brake _booster is then activated using the method described here, the motor power is increased compared to the prior art described above in such a way that the driver _generates a pedal counterforce F _pedal according to the standard driver brake force pedal counterforce relation f _pedal feels. The "increase" in the motor force of the electromechanical brake booster caused by the determination of the target differential travel Δ deviating from the standard value Δ _standard (compared to a motor force effected when the target differential travel Δ was set equal to the standard value Δ _standard ) thus causes an advantageous "force blending". . In this way, a brake actuation feel/pedal feel of the driver actuating the brake actuation element is significantly improved compared to the prior art described above. It is also pointed out that the effected “force blending” does not impair the recuperation efficiency of the method described here.

In the example described here, the at least one electric motor can be operated in its recuperative mode from a point in time t3 in such a way that the vehicle can be braked (essentially) exclusively by means of the at least one electric motor. Therefore, starting at time t3, the generator braking torque M _gen produced by the at least one electric motor is increased, while at the same time the front wheel braking pressure p _front in the front wheel wheel brake cylinders is correspondingly reduced. From a point in time t4, the front wheel brake pressure p _front is less than or equal to the brake pressure p _standard . As an advantageous further development in the method described here, at least after it has been determined or estimated that the requested vehicle deceleration is caused by the recuperative operation of the at least one electric motor, the at least one valve of the brake system is switched in such a way that, despite the driver braking force not being equal to zero, the brake pressure build-up in the front wheel wheel brake cylinders and in the rear wheel wheel brake cylinders is/is limited to a maximum of the accumulator chamber response pressure. In order to prevent the pedal counterforce F _pedal from weakening compared to the specified standard driver brake force/pedal counterforce relation f _pedal from time t4, the target differential travel Δ deviates from the standard value Δ _standard from time t4 and takes into account the driver brake force/the sensor variable corresponding to it and a second characteristic curve k ₂ that deviates from the first characteristic curve k ₁ . Preferably, when the front wheel brake pressure p _front in the front wheel wheel brake cylinders and the rear wheel brake pressure p _rear in the rear wheel wheel brake cylinders are limited to a maximum of the accumulator chamber response pressure, the target differential travel Δ is set so that it deviates from the standard value Δ _standard such that a “reduction” in the current engine force compared to an engine force caused when setting the target differential travel Δ equal to the standard value Δ _standard , the pedal counterforce F _pedal is “set” equal to the specified standard driver brake force-pedal counterforce relation fpedal. The driver thus does not feel the brake pressure limitation in the front wheel wheel brake cylinders and in the rear wheel wheel brake cylinders to a maximum of the accumulator chamber response pressure. In particular, the target difference path Δ defined as the difference in the adjustment path of the driver brake force transmission component minus the adjustment path of the motor force transmission component, while the standard value Δ _standard is equal to zero, can be set to be less than zero from time t4.

4 shows a schematic representation of a control device for at least one electromechanical brake booster of a brake system of a vehicle, or the brake system equipped therewith.

At the in 4 Schematically illustrated brake system, the electromechanical brake booster 10 is upstream of a brake master cylinder 12 of the brake system. Merely as an example, the brake system has two brake circuits, each with a front wheel wheel brake cylinder 14 and a rear wheel wheel brake cylinder 16 each. Each of the brake circuits also has a storage chamber 18 downstream of its wheel brake cylinders 14 and 16. As at least one switchable valve, each of the brake circuits also includes, for example, one wheel inlet valve 20 per wheel brake cylinder 14 and 16, one wheel outlet valve 22 per wheel brake cylinder 14 and 16, one switchover valve 24 each and one high-pressure switching valve 26 each. In addition, each of the brake circuits has a pump 28 each, the pumps 28 being operable by means of a common pump motor 30 . In the 4 shown training of the braking system is to be interpreted only as an example. It is expressly pointed out that the usability of the control device 32 described below is not limited to any special type of brake system and to any special vehicle type/motor vehicle type of the vehicle/motor vehicle equipped with the brake system.

Control device 32 has an electronic device 34, which is designed and/or programmed to define a target differential travel between a driver braking force transmission component that can be adjusted by means of a driver braking force and a motor force transmission component that can be adjusted by means of a motor force of a motor of electromechanical brake booster 10. In addition, electronic device 34 is designed and/or programmed to control the motor of electromechanical brake booster 10 by means of at least one motor control signal 34s in such a way that a differential path between the driver brake force transmission component and the motor force transmission component that corresponds to the specified target differential path can be/is set . In addition, electronic device 34 can be used to estimate or determine whether the same brake pressure build-up is effected at least in master brake cylinder 12, the connected front wheel wheel brake cylinders 14 and the connected rear wheel wheel brake cylinders 16 by means of the driver braking force and the engine force to a braking pressure which corresponds to the driver braking force according to a predetermined standard driver brake force brake pressure relation of the brake system corresponds. If necessary, the electronic device 34 is then designed and/or programmed to define a predefined standard value as the desired differential travel. Electronic device 34 can also be used to estimate or determine whether, by means of the driver's braking force and the motor force in master brake cylinder 12, at least one of front-wheel wheel brake cylinders 14 and/or at least one of rear-wheel wheel brake cylinders 16, a brake pressure build-up above that of the driver's braking force according to the specified standard Driver brake force brake pressure relation corresponding brake pressure is effected. If this is the case, then the electronic device 34 is designed and/or programmed to define the target differential travel as deviating from the standard value.

The driver braking force can be provided to electronic device 34 by means of at least one sensor variable corresponding to the driver braking force, such as at least one sensor variable of a rod travel sensor and/or differential travel sensor. Electronic device 34 can be designed and/or programmed, for example, to use at least one sensor signal from at least one sensor in the brake system, such as using at least one admission pressure signal 36s of an admission pressure sensor 36 in the brake system, to determine whether in master brake cylinder 12, at least one of the front wheel brake cylinders 14 and/or at least one of the rear wheel brake cylinders 16 of the brake pressure corresponding to the driver brake force according to the predetermined standard driver brake force-brake pressure relation or a higher brake pressure is present. Alternatively or additionally, the electronic device 34 can also be designed and/or programmed to control at least one of the valves 20, 22, 24 and 26 and/or the pump motor 30. In this case, based on the activation of at least one of the valves 20, 22, 24 and 26 and/or the pump motor 30, the electronic device 34 can itself estimate whether in the master brake cylinder 12, at least one of the front-wheel wheel brake cylinders 14 and/or at least one of the rear wheels -Wheel brake cylinder 16 of the driver braking force according to the predetermined standard driver braking force-brake pressure relation corresponding braking pressure or a higher braking pressure is present.

The control device 32 described here thus brings about all the advantages of the methods described above. In particular, the control device 32 can be designed to carry out the method steps explained above. These processes are not described again here.

Claims (10)

Method for operating an electromechanical brake booster (10) of a brake system of a vehicle, comprising the steps: determining a target differential travel (Δ) between a driver brake force transmission component that can be adjusted by means of a driver braking force and a motor force transmission component that can be adjusted by means of a motor force of a motor of the electromechanical brake booster (10). transmission component (S1); and operating the motor of the electromechanical brake booster (10) in such a way that a differential travel between the driver brake force transmission component and the motor force transmission component that corresponds to the specified setpoint differential travel (Δ) is set (S2); insofar as it is estimated or determined that by means of the driver's braking force and the motor force at least in a master brake cylinder (12), connected front wheel wheel brake cylinders (14) and connected rear wheel wheel brake cylinders (16) of the brake system, the same brake pressure build-up to a brake pressure (p _standard ) is effected, which corresponds to the driver's braking force according to a predefined standard driver braking force-brake pressure relationship of the brake system, a predefined standard value (Δ _standard ) is defined as the target differential travel (Δ), characterized in that , if it is estimated or determined, that by means of the driver's braking force and the motor force in the master brake cylinder (12), at least one of the front wheel wheel brake cylinders (14) and/or at least one of the rear wheel wheel brake cylinders (16), a brake pressure build-up via the brake pressure (p _standard ) is effected, the target D differential path (Δ) deviating from the standard value (Δ _standard ). procedure after claim 1 , insofar as it is estimated or determined that the driver braking force and the motor force in at least one of the front wheel wheel brake cylinders (14) cause a brake pressure build-up above the braking pressure (Δ _standard ) corresponding to the driver braking force according to the specified standard driver braking force-brake pressure relationship, while in at least one of the rear wheel brake cylinders (16), the brake pressure build-up is limited to a maximum of a storage chamber response pressure of at least one storage chamber (18) of the brake system, the target differential travel (Δ) taking into account a sensor variable corresponding to the driver's braking force and a first characteristic curve (k ₁ ) and deviating from the standard value (Δ _standard ). procedure after claim 2 , where it is estimated or determined that, despite the driver's braking force not being equal to zero, the brake pressure build-up in at least one of the front wheel wheel brake cylinders (14) and in at least one of the rear wheel wheel brake cylinders (16) is limited to a maximum of the accumulator chamber response pressure, the target Differential travel (Δ) taking into account the sensor variable corresponding to the driver's braking force and a second characteristic curve (k ₂ ) deviating from the first characteristic curve (k ₁ ) and/or deviating from the standard value (Δ _standard ). Method for operating a vehicle brake system equipped with an electromechanical brake booster (10), wherein, while a driver brake force is transmitted via at least one driver brake force transmission component to at least one adjustable piston of a master brake cylinder (12) of the brake system with connected front wheel wheel brake cylinders (14) and connected rear wheel - wheel brake cylinders (16) of the brake system, the electromechanical brake booster (10), the engine power of which is transmitted via at least one adjustable engine power transmission component to the at least one adjustable piston of the master brake cylinder (12), is operated according to the method according to one of the preceding claims . procedure after claim 4 , wherein for a vehicle deceleration requested by means of the driver braking force it is determined or estimated whether the requested vehicle deceleration can be effected and/or is effected by means of recuperative operation of at least one electric motor that can be used to brake the vehicle, and wherein, at least if it is determined or estimated that the requested vehicle deceleration is brought about by means of the recuperative operation of the at least one electric motor, at least one valve (20, 22, 24, 26) of the brake system is switched in such a way that, despite the driver's braking force being unequal to zero, the brake pressure builds up in at least one of the front wheel brake cylinders (14) and in at least one of the rear wheel brake cylinders (16) is limited to a maximum of the storage chamber response pressure, while if it is ruled out that the requested vehicle deceleration can be effected by means of the recuperative operation of the at least one electric motor, at least sometimes the at least a valve (20, 22, 24, 26) is switched in such a way that, by means of the driver's braking force and the engine force, the same brake pressure build-up is applied to the master brake cylinder (12), the front wheel wheel brake cylinders (14) and the rear wheel wheel brake cylinders (16). the driver braking force according to the specified standard driver braking force brake pressure relay tion of the brake system corresponding brake pressure (p _standard ) is effected. procedure after claim 5 , wherein, if it is determined or estimated that the requested vehicle deceleration can probably be effected by means of the recuperative operation of the at least one electric motor after waiting at most a predetermined maximum waiting time, the at least one valve (20, 22, 24, 26) is switched in such a way that in at least one of the front wheel wheel brake cylinders (14) the brake pressure build-up is effected via the brake pressure (p _standard ) corresponding to the driver brake force according to the specified standard driver brake force-brake pressure relationship, while in at least one of the rear wheel wheel brake cylinders (16) the brake pressure build-up is at most to the storage chamber -Response pressure is limited. Control device (32) for at least one electromechanical brake booster (10) of a braking system of a vehicle, having: an electronic device (34), which is designed and/or programmed to calculate a target differential travel (Δ) between a driver braking force transmission component that can be adjusted by means of a driver braking force and a motor force transmission component that can be adjusted by means of a motor force of a motor of the electromechanical brake booster (10), and to control the motor of the electromechanical brake booster (10) in such a way that a differential distance between the driver brake force transmission component and the motor force corresponding to the specified setpoint differential travel (Δ). -Transmission component is adjustable; it being possible to estimate or determine by means of the electronic device (34) whether the same brake pressure build-up to one brake pressure is achieved by means of the driver's braking force and the motor force at least in a master brake cylinder (12), connected front wheel wheel brake cylinders (14) and connected rear wheel wheel brake cylinders (16) of the brake system (p _standard ) is effected, which corresponds to the driver braking force according to a predefined standard driver braking force-brake pressure relationship of the brake system, and if necessary the electronic device (34) is designed and/or programmed to use a predefined standard value (Δ _standard ) as the target differential travel (Δ ), characterized in that the electronic device (34) can also be used to estimate or determine whether, using the driver's braking force and the motor force in the master brake cylinder (12), at least one of the front-wheel wheel brake cylinders (14) and/or at least one of the rear wheels -Wheel brake cylinder (16) a brake pressure build-up au is effected via the braking pressure (p _standard ) corresponding to the driver braking force according to the specified standard driver braking force-brake pressure relationship, and if necessary the electronic device (34) is designed and/or programmed to calculate the target differential travel (Δ) deviating from the standard value (Δ _default ). Control device (32) after claim 7 , wherein, if the electronic device (34) estimates or determines that by means of the driver braking force and the motor force in at least one of the front wheel wheel brake cylinders (14), a brake pressure build-up above the braking pressure (p _standard ) corresponding to the driver braking force according to the specified standard driver braking force-brake pressure relation is effected while in at least one of the rear wheel brake cylinders (16) the brake pressure build-up is limited to a maximum of a storage chamber response pressure of at least one storage chamber (18) of the brake system, the electronic device (34) is designed and/or programmed for this purpose, the setpoint differential travel (Δ) taking into account a sensor variable corresponding to the driver's braking force and a first characteristic curve (k ₁ ) and deviating from the standard value (Δ _standard ). Control device (32) after claim 7 or 8th , wherein, for a vehicle deceleration requested by means of the driver braking force, the electronic device (34) can also be used to estimate or determine whether the requested vehicle deceleration can be effected and/or is effected by means of recuperative operation of at least one electric motor of the brake system that can be used to brake the vehicle, and wherein, at least if it is determined or estimated that the requested vehicle deceleration is caused by the recuperative operation of the at least one electric motor, the electronic device (34) is designed and/or programmed to close at least one valve (20, 22, 24, 26) of the brake system in such a way switch that, despite the driver's braking force not being equal to zero, the brake pressure build-up in at least one of the front wheel wheel brake cylinders (14) and in at least one of the rear wheel wheel brake cylinders (16) is limited to a maximum of the storage chamber response pressure, while if it is impossible that the requested vehicle g deceleration can be effected by means of the recuperative operation of the at least one electric motor, the electronic device (34) is designed and/or programmed to at least sometimes switch the at least one valve (20, 22, 24, 26) in such a way that, by means of the driver's braking force and the Engine power at least in the master brake cylinder (12), the front wheel wheel brake cylinders (14) and the rear wheel wheel brake cylinders (16) the same brake pressure build-up on the driver's brake force according to the specified standard driver brake force-brake pressure relation the brake pressure corresponding to the brake system (Δ _standard ) is effected. Braking system for a vehicle, comprising: a control device (32) according to any one of Claims 7 until 9 ; the electromechanical brake booster (10), the motor of which can be controlled by the control device (32), the electromechanical brake booster (10) being upstream of a master brake cylinder (12) of the brake system in such a way that, while a driver's braking force is transmitted via at least one driver's braking force transmission component to at least one adjustable piston of the master brake cylinder (12), a motor force of the motor of the electromechanical brake booster (10) can be transmitted via at least one adjustable motor force transmission component to the at least one adjustable piston of the master brake cylinder (12); front wheel wheel brake cylinders (14) connected to the master brake cylinder (12); and rear wheel wheel brake cylinders (16) connected to the master brake cylinder (12).

Images