Method, device and motor vehicle for operating a motor vehicle

Abstract

The invention relates to a method for operating a motor vehicle (1), wherein the motor vehicle (1) has a first adjusting element (18), an actuatable second adjusting element (19) and a brake system (12) with an actuatable braking force generator (15) and a master brake cylinder (14), wherein at least one hydraulic piston is displaceably mounted in the master brake cylinder (14), wherein the first adjusting element (18) is displaceable, in particular steplessly, between a first end position and a second end position, wherein a change position (WS) is predetermined between the end positions, and wherein in the first adjusting element When the current position of the element (18) exceeds the change position (WS), an acceleration value for the motor vehicle (1) is predetermined, wherein when the current position is below the change position (WS), a first deceleration value (VW) for the motor vehicle (1) is predetermined, wherein when the first deceleration value (VW) is predetermined, the brake force generator (15) is controlled in such a way that the hydraulic piston is displaced according to the magnitude of the first deceleration value (VW), and wherein the hydraulic piston is displaced when the second adjusting element (19) is actuated by the driver of the motor vehicle (1). The first deceleration value (VW) is set to be reduced when it is detected that the second adjusting element (19) is actuated by the driver.

Description

Technical Field

[0001] The invention relates to a method for operating a motor vehicle, wherein the motor vehicle has a first adjusting element, an actuatable second adjusting element and a brake system with an actuatable brake force generator and a master brake cylinder, wherein at least one hydraulic piston is displaceably supported in the master brake cylinder, wherein the first adjusting element is displaceable, in particular steplessly, between a first end position and a second end position, wherein a switching position is predetermined between the end positions, wherein an acceleration value for the motor vehicle is predetermined when a current position of the first adjusting element exceeds the switching position, wherein a first deceleration value for the motor vehicle is predetermined when the current position lies below the switching position, wherein when the first deceleration value is predetermined, the brake force generator is actuated in such a way that the hydraulic piston is displaced according to the magnitude of the first deceleration value, and wherein the hydraulic piston is displaced when the second adjusting element is actuated by a driver of the motor vehicle.

[0002] Furthermore, the invention relates to a device for operating a motor vehicle, which device has a control unit.

[0003] Furthermore, the invention relates to a motor vehicle having such a device. Background Art

[0004] Methods and motor vehicles of the type mentioned at the outset are known from the prior art. Motor vehicles usually have a hydraulic brake system with a master brake cylinder in which at least one hydraulic piston is displaceably mounted. If the hydraulic piston is displaced, a deceleration torque is generated that decelerates the motor vehicle. Controllable electromechanical brake boosters are increasingly frequently installed in brake systems. Such brake boosters have an electric motor that is coupled to the hydraulic piston via a transmission mechanism in such a way that the hydraulic piston can be displaced by the electric motor.

[0005] In addition, motor vehicles, especially those equipped with electric engines, increasingly have a first adjusting element which has a so-called one-pedal function. With such an adjusting element, acceleration or deceleration can be optionally predefined for the motor vehicle. The first adjusting element can be moved between a first end position and a second end position, wherein a change position is predefined between the end positions. In order to operate the motor vehicle with the aid of the first adjusting element, the current position of the first adjusting element is monitored. Here, an acceleration value for the motor vehicle is predefined when the current position of the first adjusting element exceeds the change position. If the current position of the first adjusting element is below the change position, a first deceleration value for the motor vehicle is predefined. The one-pedal function described above is also referred to as one-pedal driving (OPD). If the motor vehicle has not only a first adjusting element with a one-pedal function but also a brake system with a controllable brake force generator, when the first deceleration value is predefined, the brake force generator or the electric motor of the brake force generator is usually controlled in such a way that the hydraulic piston is displaced according to the magnitude of the first deceleration value. The extent of the displacement of the hydraulic piston corresponds to the extent of the deceleration of the motor vehicle.

[0006] Furthermore, the motor vehicle usually has an actuable second adjusting element, such as, for example, a brake pedal, wherein the hydraulic piston is displaced when the second adjusting element is actuated by the driver of the motor vehicle. In order to actuate the second adjusting element, the driver must overcome a reaction force that impedes the actuation. The reaction force is described by a deceleration-reaction force characteristic curve, which describes the deceleration of the motor vehicle as a function of the reaction force.

[0007] If there is no first adjusting element with a single-pedal function, the deceleration-reaction force characteristic curve usually has a characteristic trend. The driver is accustomed to this trend. If the driver wants to increase the deceleration of the motor vehicle, he must overcome a certain first reaction force, for example in order to actuate the second adjusting element that has not been actuated so far.

[0008] However, if there is also a first adjusting element with a single-pedal function, then, as described above, the brake force generator is actuated in such a way that the hydraulic piston is displaced when the first deceleration value is predetermined. The deceleration of the motor vehicle corresponds to the extent of the displacement of the hydraulic piston. If the driver now wants to increase the deceleration of the motor vehicle by actuating the second adjusting element, which has not been actuated so far, he must overcome a reaction force that is greater than the first reaction force. This is caused by the fact that the hydraulic piston has already been displaced and the motor vehicle has already been decelerated. This is not something that the driver is used to and is therefore undesirable. Summary of the invention

[0009] The method according to the invention with the features of claim 1 achieves that the reaction force that the driver must overcome in order to increase the deceleration of the motor vehicle corresponds at least substantially to the expected reaction force. To this end, the method according to the invention with the features of claim 1 is characterized in that the first deceleration value is reduced when it is detected that the second adjusting element is operated by the driver. Then, if it is detected that the driver operates the second adjusting element, the first deceleration value is reduced. Due to the reduction of the first deceleration value, the deceleration of the motor vehicle is also reduced at least temporarily. Accordingly, the reaction force that the driver must overcome in order to increase the deceleration of the motor vehicle again by operating the second adjusting element is reduced. Preferably, the second adjusting element can be adjusted between the third end position and the fourth end position, especially steplessly. Preferably, the reaction force is provided by a spring mechanism, which is compressed when the second adjusting element is operated by the driver. The spring mechanism therefore pushes the second adjusting element in the direction of the third end position and especially until it is in the third end position. If the driver does not provide an operating force that hinders the reaction force, the second adjusting element is in a non-operated state. The manipulation of the adjusting element is understood to mean that the driver provides an actuating force acting on the second adjusting element, by which the position of the second adjusting element is moved in the direction of the fourth end position compared to the position of the second adjusting element in the non-manipulated state. Preferably, the position of the second adjusting element is not affected by the manipulation of the brake force generator. In the non-manipulated state, the position of the second adjusting element then corresponds to the third end position. Therefore, if the brake force generator is manipulated in such a way that the hydraulic piston is displaced, the second adjusting element stays in the third end position. Alternatively, the second adjusting element is coupled to the hydraulic piston and / or to the actuating element of the brake force generator that is displaceably supported in such a way that the position of the second adjusting element is changed by the manipulation of the brake force generator. For example, if the brake force generator is manipulated in such a way that the hydraulic piston is displaced, the second adjusting element is moved in the direction of the fourth end position. Accordingly, the position of the second adjusting element is variable in the non-manipulated state and is affected by the first deceleration value and thereby the manipulation of the brake force generator or the degree of displacement of the hydraulic piston.

[0010] According to a preferred embodiment, it is provided that a second deceleration value is predetermined when the second adjusting element is actuated, wherein the brake force generator is controlled in such a way that the hydraulic piston is displaced according to the magnitude of the second deceleration value when the second adjusting element is actuated. The hydraulic piston is then displaced at least by means of the brake force generator when the second adjusting element is actuated. Alternatively or additionally, a mechanical coupling exists between the second adjusting element and the hydraulic piston, so that the hydraulic piston is displaced due to the mechanical coupling when the second adjusting element is actuated. Preferably, the magnitude of the second deceleration value corresponds to the degree of actuation of the second adjusting element in such a way that the second deceleration value is increased when the degree of actuation is increased. As described above, a reduction in the deceleration of the motor vehicle is at least temporarily caused by a reduction in the first deceleration value. If the second deceleration value is predetermined when the second adjusting element is actuated, the temporary reduction in the deceleration is preferably achieved in such a way that the first deceleration value is reduced more than the second deceleration value is increased. Alternatively or additionally, the reduction in the deceleration of the motor vehicle is preferably achieved in that a starting braking range is predefined adjacent to the third end position, wherein, when the position of the second adjusting element is in the starting braking range, no second deceleration value is predefined or a second deceleration value of zero is predefined.

[0011] According to a preferred embodiment, it is provided that the first deceleration value is continuously changed as a function of the degree of actuation of the second adjusting element. Such a change of the first deceleration value is particularly comfortable for the driver. In contrast, a discontinuous or step-wise change of the first deceleration value may impair comfort. If the degree of actuation of the second adjusting element is reduced, the first deceleration value is preferably increased again.

[0012] Preferably, the first deceleration value is reduced immediately upon detection of the actuation of the second actuating element. The first deceleration value is then reduced as quickly as possible. Since the first deceleration value is reduced immediately, a state is quickly reached from which the increase in the reaction force is accompanied by an increase in the deceleration of the motor vehicle as desired.

[0013] The first deceleration value is preferably reduced independently of the displacement of the first adjusting element. If the second adjusting element is then actuated, the first deceleration value is also reduced if the first adjusting element is not changed or remains constant.

[0014] According to a preferred embodiment, the brake system has at least one friction brake mechanism, wherein the master brake cylinder is fluidically connected to a slave cylinder of the friction brake mechanism so that the friction brake mechanism is actuated when the hydraulic piston is displaced. The motor vehicle is then decelerated due to the actuation of the friction brake mechanism. This can be implemented particularly easily in terms of technology.

[0015] According to a preferred embodiment, the motor vehicle has at least one electric motor, wherein the electric motor is operated as a generator depending on the extent of the displacement of the hydraulic piston. The motor vehicle is decelerated by the generator operation of the electric motor. The hydraulic fluid delivered from the master brake cylinder when the hydraulic piston is displaced is preferably delivered to at least one low-pressure fluid reservoir fluidically connected to the master brake cylinder. As a result, actuation of the friction brake mechanism is reduced or prevented.

[0016] The device according to the invention is used for operating a motor vehicle having a first adjusting element which can be moved, in particular continuously, between a first end position and a second end position, a second actuable adjusting element, and a brake system with a brake force generator and a master brake cylinder, wherein at least one hydraulic piston is supported displaceably in the master brake cylinder. The device according to the invention has the features of claim 8, which are distinguished by a control device which is specially designed to carry out the method according to the invention when used in accordance with the provisions. The advantages already mentioned also result from this. Further preferred features and feature combinations are derived from the previous description and from the claims.

[0017] The motor vehicle according to the invention has a first adjusting element that can be moved, in particular steplessly, between a first end position and a second end position, a second controllable adjusting element, and a brake system, wherein the brake system has a controllable brake force generator and a master brake cylinder in which at least one hydraulic piston is supported displaceably. The motor vehicle has the features of claim 9, which are distinguished by the device according to the invention. The advantages already mentioned also result from this. Further preferred features and feature combinations are derived from the preceding description and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention is explained in detail below with the aid of the accompanying drawings.

[0019] Figure 1 A motor vehicle is shown in a simplified diagram,

[0020] Figure 2 A method for operating a motor vehicle is shown and

[0021] Figure 3The deceleration-reaction force-characteristic curve is shown. DETAILED DESCRIPTION

[0022] Figure 1 A motor vehicle 1 is shown in a simplified diagram. The motor vehicle 1 has four wheels 2 and 3, wherein the wheels 2 are assigned to a front axle 4 and the wheels 3 are assigned to a rear axle 5. The motor vehicle 1 also has a drive 6 with a motor 7, which is an electric motor 7 that can be operated as a generator. The motor 7 is connected to the wheels 2 of the front axle 4 via a differential transmission 8 and shafts 9, 10 and 11, so that the wheels 2 can be driven by the motor 7.

[0023] Furthermore, the motor vehicle 1 has a brake system 12. The brake system 12 has four friction brake mechanisms 13, wherein each of the wheels 2 and 3 is respectively assigned another friction brake mechanism of the friction brake mechanisms 13. In order to actuate the friction brake mechanisms 13, the brake system 12 has a master brake cylinder 14, which is designed here as a tandem master brake cylinder 14, so that two hydraulic pistons (not shown) are displaceably supported in the master brake cylinder 14. The master brake cylinder 14 is fluidically connected to the slave cylinders of the friction brake mechanisms 13.

[0024] The master brake cylinder 14 is associated with a brake force generator 15. The brake force generator 15 has a controllable electric motor. The electric motor is coupled to a hydraulic piston in such a way that the hydraulic piston is displaced when the electric motor is controlled.

[0025] Furthermore, the motor vehicle 1 has a device 16 with a control device 17. The control device 17 is connected to the engine 7 in terms of communication technology and is designed to control the engine 7. Furthermore, the control device 17 is connected to the brake force generator 15 in terms of communication technology and is designed to actuate the brake force generator 15 or an electric motor thereof.

[0026] Furthermore, the motor vehicle has a first adjusting element 18. The first adjusting element 18 is designed as a pedal and can be moved steplessly between a first end position and a second end position. The position of the first adjusting element in the first end position corresponds to a percentage value of 0% with respect to the adjustment travel from the first end position to the second end position. In the second end position, the position of the first adjusting element 18 corresponds to a percentage value of 100%. The first adjusting element 18 is connected to the control device 17 in terms of communication technology, so that the current position of the first adjusting element 18 is provided to the control device 17. The control device 17 predetermines virtual changeover positions between the end positions of the first adjusting element 18.

[0027] If the position of the first adjusting element 18 exceeds the change position, the control device 17 outputs an acceleration value for the motor vehicle 1. The current position of the first adjusting element 18 is then in the acceleration range between the change position and the second end position. If the acceleration value is predetermined, the control device 17 controls the engine 7 in such a way that the motor vehicle 1 is accelerated.

[0028] If the position of the first adjusting element 18 is below the change position, the control device 17 specifies a first deceleration value for the motor vehicle 1. The current position is then in the deceleration range between the first end position and the change position. If a first deceleration value is specified for the motor vehicle 1, the control device 17 controls the power generator 15 in such a way that the hydraulic piston is displaced according to the magnitude of the first deceleration value. If the first deceleration value increases, the extent of the displacement of the hydraulic piston also increases.

[0029] If the hydraulic piston is displaced, the motor vehicle 1 is decelerated, wherein the degree of deceleration of the motor vehicle 1 corresponds to the degree of displacement of the hydraulic piston. By displacing the hydraulic piston, hydraulic fluid is delivered from the master brake cylinder 14. Preferably, the motor vehicle 1 is decelerated by actuating the friction brake mechanism 13. For this purpose, the hydraulic fluid is delivered to the slave cylinder. Alternatively, the motor vehicle 1 is decelerated preferably by generator operation of the engine 7. In this case, the hydraulic fluid is delivered to at least one low-pressure fluid reservoir (not shown) to prevent actuation of the friction brake mechanism 13.

[0030] Furthermore, the motor vehicle 1 has a second adjusting element 19, which is a brake pedal 19. The brake pedal 19 can be moved continuously between a third end position and a fourth end position. The position of the brake pedal 19 in the third end position corresponds to a percentage value of 0% with respect to the adjustment travel from the third end position to the fourth end position. In the fourth end position, the position of the brake pedal 19 corresponds to a percentage value of 100%.

[0031] The brake pedal 19 is provided with a spring mechanism 20 which pushes the brake pedal 19 in the direction of the third end position and in particular into the third end position. The brake pedal 19 can therefore be moved in the direction of the fourth end position against the spring force of the spring mechanism 20, so that the spring force represents a reaction force which must be overcome in order to move the brake pedal 19 in the direction of the fourth end position. The spring mechanism 20 is held in a prestressed manner between the brake pedal 19 on the one hand and a housing (not shown) on the other hand, in particular a housing of the brake force generator 15. However, the spring mechanism 20 is supported directly or indirectly on the brake pedal 19 on the one hand and directly or indirectly on the housing on the other hand.

[0032] The brake pedal 19 can be actuated by the driver of the motor vehicle 1. Actuation of the brake pedal 19 is understood to mean that the driver applies an actuation force to the brake pedal 19 such that the brake pedal 19 moves in the direction of the fourth end position compared to the position assumed by the brake pedal 19 in the non-actuated state.

[0033] In this case, the brake pedal 19 is mechanically coupled to the hydraulic piston in such a way that the hydraulic piston is displaced by the mechanical coupling when the brake pedal 19 is actuated. According to another exemplary embodiment, such a mechanical coupling between the brake pedal 19 and the hydraulic piston is omitted.

[0034] Here, the brake pedal 19 is coupled to a displaceably mounted actuating element of the brake force generator 15 in such a way that the brake pedal 19 is moved in the direction of the fourth end position when the brake force generator 15 is actuated in such a way as to displace the hydraulic piston. Accordingly, the position of the brake pedal 19 in the non-actuated state is variable and is influenced by the magnitude of the first deceleration value and thus the degree of actuation of the brake force generator 19 or the displacement of the hydraulic piston.

[0035] The brake pedal 19 is connected to the control device 17 in terms of communication technology, so that the degree of actuation of the brake pedal 19 or the current position of the brake pedal 19 is provided to the control device 17. If the brake pedal 19 is actuated, the control device 17 predetermines a second deceleration value for the motor vehicle 1. If the second deceleration value for the motor vehicle 1 is predetermined, the control device 17 controls the power generator 15 in such a way that the hydraulic piston is displaced according to the magnitude of the second deceleration value. If the second deceleration value increases, the degree of displacement of the hydraulic piston also increases.

[0036] Refer to the following Figure 2 An advantageous method for operating a motor vehicle 1 is described. To this end, Figure 2A first graph A, a second graph B and a third graph C are shown.

[0037] In the first diagram A, percentage values ​​of the position of the first adjusting element 18 are shown as a function of time t. In the second diagram B, the first deceleration value VW is shown as a function of time t. In the third diagram C, percentage values ​​of the position of the brake pedal 19 are shown.

[0038] Between the first time T1 and the second time T2, the position of the first adjusting element 18 is in the acceleration range. Accordingly, no first deceleration value VW is specified between the times T1 and T2. The position of the brake pedal 19 corresponds to the third end position.

[0039] Between the second moment T2 and the third moment T3, the first adjusting element 18 is moved from the change position WS to the first end position, so that at the third moment T3, the position of the first adjusting element 18 corresponds to the first end position. The position of the first adjusting element 18 is kept constant below. Since the position of the first adjusting element 18 is in the deceleration range between the moments T2 and T3, the control device 17 predetermines the first deceleration value VW. Since the first adjusting element 18 is moved to the first end position, the magnitude of the first deceleration value VW is continuously increased between the moments T2 and T3 until the magnitude of the first deceleration value reaches the maximum value MW. Since the first deceleration value VW is predetermined, the control device 17 controls the power generator 15 from the second moment T2 so that the brake generator 15 moves the hydraulic piston. The extent of the displacement of the hydraulic piston corresponds to the magnitude of the first deceleration value VW. If the first deceleration value VW is increased, the extent of the displacement of the hydraulic piston is also increased. Due to the coupling of the brake pedal 19 with the hydraulic piston and / or with the actuating element of the brake force generator 15, the brake pedal 19 moves in the direction of the fourth end position. In this case, no actuating force is provided by the driver. In this regard, the brake pedal 19 is in a non-actuated state between the times T2 and T3.

[0040] Starting from the fourth time T4, the brake pedal 19 is actuated by the driver. The driver then provides an actuation force that exceeds the reaction force, so that the brake pedal 19 is moved by the driver in the direction of the fourth end position. Between the fourth time T4 and the fifth time T5, the brake pedal 19 is continuously moved in the direction of the fourth end position, so that the percentage value of the position of the brake pedal 19 continuously increases. The actuation of the brake pedal 19 is detected by the control device 17. Therefore, the control device 17 continuously reduces the magnitude of the first deceleration value VW between the time T4 and T5.

[0041] From the sixth time T6, the degree of actuation of the brake pedal 19 is reduced. The brake pedal 19 is then moved again in the direction of the third end position by the reaction force until the brake pedal 19 is again in the non-actuated state at the seventh time T7. The reduction in the actuation of the brake pedal 19 is detected by the control device 17. Therefore, the control device 17 continuously increases the magnitude of the first deceleration value VW between the times T6 and T7.

[0042] Since the brake pedal 19 is actuated between the times T4 and T7, the control device 17 also specifies a second deceleration value between these times. Figure 2 The trend of the second deceleration value is shown in FIG.

[0043] Figure 3 A fourth diagram D is shown in which various deceleration-reaction force characteristic curves are shown. A deceleration-reaction force characteristic curve is a characteristic curve which describes the deceleration V of the motor vehicle 1 as a function of the reaction force F provided by the spring device 20 .

[0044] The first deceleration-reaction force-characteristic curve L1 describes the deceleration of the motor vehicle 1 in relation to the reaction force F provided by the spring device 20 when the one-pedal function of the first adjusting element 18 is inactive or when the first adjusting element with a one-pedal function is missing. If the one-pedal function is inactive, an acceleration value is always predetermined when the first adjusting element 18 is actuated, as is known from a conventional accelerator pedal. Figure 3 It can be seen that the driver, starting from the hitherto unactuated second adjusting element 19 , must overcome a counterforce having a certain first value W1 in order to increase the deceleration of the motor vehicle 1 .

[0045] The second deceleration-reaction force-characteristic curve L2 describes the deceleration V of the motor vehicle 1 in relation to the reaction force F provided by the spring mechanism 20 when the single-pedal function of the first adjusting element 18 is active. The position of the first adjusting element 18 is in the deceleration range. In this regard, the first deceleration value VW is predetermined and the motor vehicle 1 is decelerated. If the first deceleration value VW is not reduced when the brake pedal 19 is actuated, the driver must overcome a reaction force having a specific second value W2 in order to increase the deceleration V of the motor vehicle 1, as can be seen from the characteristic curve L2. The value W2 is significantly higher than the value W1. For the driver, it is not accustomed that he must overcome such a high reaction force F in order to increase the deceleration V of the motor vehicle 1.

[0046] The third deceleration-reaction force characteristic curve L3 also describes the deceleration V of the motor vehicle 1 in relation to the provided reaction force F when the one-pedal function of the first adjusting element 18 is active. In the case of the third deceleration-reaction force characteristic curve L3, the position of the first adjusting element 18 is also in the deceleration range, so that the first deceleration value VW is predetermined and the motor vehicle 1 is decelerated. However, if the driver overcomes the reaction force F and thereby actuates the brake pedal 19, the first deceleration value VW is reduced, as previously described with reference to Figure 2 As described. Therefore, the deceleration V of the motor vehicle 1 is also temporarily reduced. Therefore, the driver only needs to overcome a reaction force having a certain third value W3 between the first value W1 and the second value W2 to increase the deceleration V of the motor vehicle 1. If the driver overcomes the reaction force having the value W2, the increase in the second deceleration value exceeds the decrease in the first deceleration value VW, so that the deceleration V of the vehicle increases overall. Because the third value W3 is smaller than the second value W2, the operation of the brake pedal 19 according to the third characteristic curve L3 appears more comfortable to the driver than the operation of the brake pedal 19 according to the second characteristic curve L2.

Claims

1. A method for operating a motor vehicle, in, The motor vehicle (1) comprises a first adjusting element (18), an actuable second adjusting element (19) and a brake system (12), the brake system having an actuable braking force generator (15) and a master brake cylinder (14), wherein at least one hydraulic piston is displaceably supported in the master brake cylinder (14), wherein the first adjusting element (18) is movable between a first end position and a second end position, wherein a switching position (WS) is predetermined between the end positions, wherein a switching position (WS) for the motor vehicle is predetermined when the current position of the first adjusting element (18) exceeds the switching position (WS) Acceleration value of a vehicle (1), wherein a first deceleration value (VW) for the motor vehicle (1) is predetermined when the current position is below the change position (WS), wherein the brake force generator (15) is controlled in such a way that the hydraulic piston is displaced according to the magnitude of the first deceleration value (VW) when the first deceleration value (VW) is predetermined, and wherein the hydraulic piston is displaced when the second adjusting element (19) is actuated by the driver of the motor vehicle (1), characterized in that the first deceleration value (VW) is reduced when it is detected that the second adjusting element (19) is actuated by the driver.

2. The method according to any one of the preceding claims, It is characterized in that When the second adjusting element (19) is actuated, a second deceleration value is predetermined, wherein when the second deceleration value is predetermined, the brake force generator (15) is actuated in such a way that the hydraulic piston is displaced according to the magnitude of the second deceleration value.

3. The method according to claim 1, It is characterized in that The first adjusting element (18) is continuously movable between a first end position and a second end position.

4. The method according to claim 1, It is characterized in that The first deceleration value (VW) is continuously changed depending on the degree of actuation of the second adjusting element (19).

5. The method according to claim 1, It is characterized in that Following detection of the actuation of the second adjusting element (19), the first deceleration value (VW) is subsequently reduced.

6. The method according to claim 1, It is characterized in that The first deceleration value (VW) is reduced independently of a movement of the first adjusting element (18).

7. The method according to claim 1, It is characterized in that The brake system (12) has at least one friction brake mechanism (13), wherein the master brake cylinder (14) is fluidically connected to a slave cylinder of the friction brake mechanism (13), so that the friction brake mechanism (13) is actuated when a hydraulic piston is displaced.

8. The method according to claim 1, It is characterized in that The motor vehicle (1) has at least one electric machine (7), wherein the electric machine (7) is operated in generator mode as a function of the extent of the displacement of the hydraulic piston.

9. Devices for operating motor vehicles, in, The motor vehicle (1) has a first adjusting element (18) which can be moved between a first end position and a second end position, an actuable second adjusting element (19), and a brake system (12) with a brake force generator (15) and a master brake cylinder (14), wherein at least one hydraulic piston is supported displaceably in the master brake cylinder (14), and is characterized by a control device (17) which is specially designed to implement a method according to any of the preceding claims 1 to 8 when used in accordance with the regulations.

10. A motor vehicle having a first adjusting element (18) which can be moved between a first end position and a second end position, a second actuable adjusting element (19) and a brake system (12), in, The brake system (12) has a controllable brake force generator (15) and a master brake cylinder (14) in which at least one hydraulic piston is displaceably mounted, and is characterized by a device (16) according to claim 9.

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