Method for operating a motor vehicle, controller, and motor vehicle

Abstract

The present invention relates to a method for operating a motor vehicle having a drive assembly with an electric drive engine, a friction brake system, and an adjusting element, wherein the adjusting element is displaceable, in particular steplessly, between a first end state and a second end state, wherein the position of the adjusting element in the first end state corresponds to a percentage value of 0%, and the position of the adjusting element in the second end state corresponds to a percentage value of 100%. When the position of the adjusting element has a percentage value greater than a predetermined threshold value, an acceleration torque for the motor vehicle is predetermined, and when the position of the adjusting element has a percentage value less than the threshold value, a deceleration torque for the motor vehicle is predetermined. The friction brake system is actuated so that it at least partially, in particular completely, generates the predetermined deceleration torque.

Description

Technical Field

[0001] The present invention relates to a method for operating a motor vehicle, which has a drive component, a friction brake system and an adjusting element, wherein the drive component has an electric drive engine, and the friction brake system is in particular a hydraulic friction brake system, wherein the adjusting element can be displaced in an in particular stepless manner between a first end state and a second end state, wherein the position of the adjusting element in the first end state corresponds to a percentage value of 0% and the position of the adjusting element in the second end state corresponds to a percentage value of 100%, wherein when the position of the adjusting element has a percentage value greater than a predetermined threshold value, an acceleration torque for the motor vehicle is predetermined, and wherein when the position of the adjusting element has a percentage value less than the threshold value, a deceleration torque for the motor vehicle is predetermined.

[0002] Furthermore, the present invention relates to a controller for executing the above method.

[0003] Furthermore, the present invention relates to a motor vehicle having a control unit as described above. Background Art

[0004] The prior art already discloses methods and motor vehicles of the type mentioned at the outset. To ensure reliable deceleration of the motor vehicle, these vehicles typically have a friction brake system. Furthermore, hybrid vehicles and electric vehicles each have a drive assembly having at least one electric drive machine.

[0005] Furthermore, hybrid and electric vehicles increasingly feature control elements, such as accelerator pedals, that have a so-called single-pedal function. Such control elements are typically movable between a first end state and a second end state, wherein the position of the control element in the first end state corresponds to a percentage value of 0%, and the position of the control element in the second end state corresponds to a percentage value of 100%. In the case of control elements with a single-pedal function, an acceleration torque for the vehicle is specified when the position of the control element has a percentage value greater than a predetermined threshold value, and a deceleration torque is specified when the position of the control element has a percentage value less than the predetermined threshold value. Summary of the Invention

[0006] The method according to the present invention has the advantage that it can provide a sufficient deceleration torque for decelerating the vehicle even when the relative speed of the vehicle relative to the ground is low. To this end, the present invention provides for controlling the friction brake system to generate the deceleration torque so that the friction brake system at least partially, and in particular completely, generates the predetermined deceleration torque. In other words, the friction brake system generates the predetermined deceleration torque either alone or in combination with at least one other device of the vehicle that is designed to generate the deceleration torque.

[0007] According to a preferred embodiment, the electric drive engine of the drive assembly is operated in a generator-like manner to generate a deceleration torque, so that the electric drive engine at least partially generates a predetermined deceleration torque. This results in the advantage that by operating the electric drive engine in a generator-like manner, braking energy is recovered in the form of electrical energy, thereby increasing the efficiency of the vehicle. Furthermore, in particular, the friction brake system is relieved of load, thereby reducing wear on the friction brake system. For example, the friction brake system is preferably activated to generate a deceleration torque only when, for example due to a low relative speed of the vehicle, it is not possible to ensure the predetermined deceleration torque by operating the electric drive engine alone in a generator-like manner.

[0008] Preferably, the relative speed of the motor vehicle relative to the ground, in particular the relative speed of the vehicle body relative to the ground, is detected, and the predefined deceleration torque is varied as a function of the detected relative speed. This results in the following advantage: the deceleration process of the motor vehicle can be individually adjusted. For example, this allows for comfort-oriented deceleration of the motor vehicle. For example, the predefined deceleration torque is varied when a predefined relative speed is detected to be exceeded or not exceeded. In particular, a plurality of relative speeds are predefined, and the deceleration torque is varied when these relative speeds are exceeded and / or not exceeded. In particular, the deceleration torque is varied steplessly with the relative speed. If, in addition to the friction brake system, at least one further device (e.g., an electric drive) is actuated to generate the deceleration torque, the percentage of the deceleration torque generated by the friction brake system or the at least one further device is preferably varied as a function of the relative speed. For example, as the relative speed decreases, the percentage generated by the friction brake system is increased.

[0009] According to a preferred embodiment, the deceleration torque is reduced when the relative speed decreases. As a result, when the motor vehicle is decelerated, an excessive sudden upward movement of the motor vehicle can be avoided. Or it is considered as a disruptive deceleration jerk, so as to ensure a comfortable deceleration or a comfortable parking (soft stop) of the motor vehicle.

[0010] Preferably, a first threshold speed is predefined, wherein the deceleration torque is reduced only when the detected relative speed is less than the first threshold speed. Thus, if a relative speed reduction is detected but the relative speed is still greater than the first threshold speed, the deceleration torque is at least not reduced. This ensures smooth deceleration of the vehicle when the relative speed of the vehicle is greater than the first threshold speed.

[0011] According to a preferred embodiment, a second threshold speed is predefined, which is greater than a first threshold speed, wherein when a relative speed is detected that is greater than the first threshold speed and less than the second threshold speed, the deceleration torque is increased as the relative speed decreases. By predefining the deceleration torque in this way, a particularly smooth, yet still comfortable deceleration or stopping of the motor vehicle (active soft stop) is achieved.

[0012] The deceleration torque is preferably predetermined based on a previously stored characteristic curve. In particular, the characteristic curve is determined during preliminary tests and shows a predetermined or to-be-predetermined deceleration torque as a function of the detected relative speed of the vehicle. This results in the advantage that a suitable deceleration torque for achieving comfortable deceleration or parking can be assigned to a plurality of relative speeds of the vehicle.

[0013] Preferably, the characteristic curve has a slope that increases and / or decreases as the relative speed decreases. This results in the advantage that the deceleration or parking process of the motor vehicle can be individually adjusted. For example, depending on the selected driving mode and / or the configuration of the motor vehicle, characteristic curves with different slopes and / or slope variations can be used in the motor vehicle in which the method is carried out.

[0014] The motor vehicle is preferably decelerated to a standstill by a predetermined deceleration torque. The present method is particularly advantageously suitable for this purpose because, even at a low relative speed of the motor vehicle or even when the motor vehicle is stationary, a braking torque can still be generated by the friction brake system that is sufficient to decelerate the motor vehicle to a standstill or to hold the motor vehicle at a standstill.

[0015] According to a preferred embodiment, a minimum value for the deceleration torque is predefined, wherein the deceleration torque does not decrease below the minimum value. This ensures, on the one hand, that a sufficient deceleration torque is predefined for decelerating the vehicle, in particular for bringing the vehicle to a standstill. Furthermore, it ensures, on the other hand, that the vehicle remains stationary after reaching a standstill. Since the electric drive engine cannot generate a generator-like deceleration torque when the vehicle is stationary, preferably only the friction brake system is actuated to hold the vehicle.

[0016] According to a preferred embodiment, a reference deceleration torque is generated by a friction braking system, wherein the difference between the reference deceleration torque and a predetermined deceleration torque is at least substantially compensated by operating the electric drive machine in a motor-like or generator-like manner. Thus, the friction braking system generates a reference deceleration torque that differs from the predetermined deceleration torque, i.e., it is greater or less than the predetermined deceleration torque. To at least substantially compensate, and in particular, completely compensate, the difference between the reference deceleration torque and the predetermined deceleration torque, a compensation torque is generated by the electric motor. To this end, the electric motor is operated in a motor-like manner when the reference deceleration torque is greater than the predetermined deceleration torque, and in a generator-like manner when the reference deceleration torque is less than the predetermined deceleration torque. This enables particularly precise and rapid control of the deceleration torque. In particular, the reference deceleration torque remains constant when the relative speed changes, so that the predetermined deceleration torque can be changed solely by varying the compensation torque.

[0017] The control unit according to the invention for the aforementioned motor vehicle is distinguished in that the control unit is configured to carry out the method according to the invention during normal use. This results in the advantages already mentioned.

[0018] The motor vehicle according to the invention comprises a drive assembly having an electric drive machine, a friction brake system, and an adjusting element, wherein the adjusting element is displaceable, in particular steplessly, between a first end state and a second end state, wherein the position of the adjusting element in the first end state corresponds to a percentage value of 0% and the position of the adjusting element in the second end state corresponds to a percentage value of 100%, and the motor vehicle comprises a control unit according to the invention. This also results in the advantages already mentioned. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is explained in more detail below with reference to the drawings. For this purpose, it is shown:

[0020] Figure 1 Simplified schematic diagram of a motor vehicle,

[0021] Figure 2 Overview of characteristic curves for different advantageous parking strategies for motor vehicles,

[0022] Figure 3 An advantageous method for operating a motor vehicle. DETAILED DESCRIPTION

[0023] Figure 1A simplified schematic diagram shows a motor vehicle 1. In the present case, motor vehicle 1 has four wheels 2 and 3, with wheel 2 assigned to a front axle 4 and wheel 3 assigned to a rear axle 5. Furthermore, motor vehicle 1 has a drive assembly 6 having an electric drive engine 7 capable of generator operation. Drive engine 7 is connected to wheels 2 of front axle 4 via a differential transmission 8 and shafts 9, 10, and 11, so that wheels 2 can be driven by drive engine 7. Furthermore, motor vehicle 1 has a friction brake system 12, which in the present case includes friction brake devices 13 assigned to wheels 2 of front axle 4 for generating a deceleration torque MV. In the present case, friction brake device 13 is hydraulically actuable. Alternatively, friction brake system 12 may include friction brake devices 13 that can be actuated by an electric motor or pneumatically.

[0024] exist Figure 1 The motor vehicle 1 shown in FIG. 1 has an adjusting element 14 designed as an accelerator pedal and is continuously displaceable between a first end state and a second end state. The position of the adjusting element 14 in the first end state corresponds to a percentage value of 0%, and the position of the adjusting element 14 in the second end state corresponds to a percentage value of 100%. Using the adjusting element 14, an acceleration torque or a deceleration torque MV for the motor vehicle 1 can be optionally predefined. The acceleration torque is predefined when the position of the adjusting element 14 has a percentage value greater than a predefined threshold value, and the deceleration torque MV is predefined when the position of the adjusting element 14 has a percentage value less than a predefined threshold value.

[0025] To predetermine an acceleration torque or deceleration torque MV, motor vehicle 1 includes a controller 15 , which is connected to actuating element 14 on the one hand and to drive engine 7 and friction brake device 13 on the other hand. When an acceleration torque is predetermined based on the position of actuating element 14 , controller 15 controls drive engine 7 to generate the acceleration torque. When a deceleration torque MV is predetermined, controller 14 controls at least friction brake device 13 to generate the deceleration torque MV. Optionally, controller 15 also controls drive engine 7 to generate a generator-like deceleration torque MV.

[0026] Figure 2 Characteristic curves S1, S2, S3 and S4 are shown for different advantageous deceleration processes of the motor vehicle 1. In this case, a deceleration torque MV is shown as a function of the relative speed v of the motor vehicle 1, which is predetermined by the controller 15 for the motor vehicle 1 when the position of the control element 14 has a percentage value less than a threshold value. Figure 2 As shown, the deceleration torque MV changes according to the relative speed v.

[0027] According to the characteristic curves S1, S2 and S3, if the relative speed v is greater than the predetermined threshold speed v1, the predetermined deceleration torque MV is kept constant at the value MV0 when the relative speed v of the motor vehicle 1 decreases. If the detected relative speed v is less than the threshold speed v1, the deceleration torque MV is reduced as the relative speed v decreases. By reducing the deceleration torque MV, a particularly comfortable deceleration of the motor vehicle 1 is achieved, in particular until the motor vehicle 1 comes to a standstill. In particular, deceleration jerks are avoided when the motor vehicle 1 is parked. Figure 2 As shown, the deceleration torque does not decrease below a predetermined minimum value MV1. This ensures that the motor vehicle 1 remains stationary after deceleration to a standstill. The characteristic curves S1, S2, and S3 differ from one another because they each have different slopes or slope changes in the relative speed range Δv1 with a decreasing relative speed.

[0028] According to the characteristic curve S2 , the deceleration torque MV decreases linearly with the relative speed v. In contrast, the slope of the characteristic curve S1 increases as the relative speed v decreases, and the slope of the characteristic curve S3 decreases as the relative speed v decreases.

[0029] Since, in addition to the first threshold speed v2 (wherein, if the relative speed v is less than the first threshold speed v2, the deceleration torque MV is reduced when the relative speed v decreases), a second threshold speed v3 greater than the first threshold speed v2 is predetermined, and if a relative speed v greater than the first threshold speed v2 and less than the second threshold speed v3 is detected, the deceleration torque MV is increased when the relative speed v decreases, therefore, Figure 2 Characteristic curve S4 shown in FIG differs from characteristic curves S1, S2, and S3. This presetting of the deceleration torque MV allows for a particularly smooth, yet still comfortable, deceleration or stopping of motor vehicle 1. According to characteristic curve S4, a minimum value MV2 is predefined for the deceleration torque MV, below which the deceleration torque MV is not reduced.

[0030] according to Figure 2 , the first threshold speed v1 of the characteristic curves S1, S2 and S3 corresponds to the second threshold speed v3 of the characteristic curve S4. Figure 2 According to further embodiments of the characteristic curves S1 , S2 , S3 and S4 , the first threshold speed v1 of the characteristic curves S1 , S2 and S3 is different from the second threshold speed v3 of the characteristic curve S4 .

[0031] Figure 3An advantageous method for operating a motor vehicle 1 is shown. In a first step S1, a percentage value of the position of an actuating element 14 is detected. In a subsequent step S2, an acceleration torque for the motor vehicle 1 is predetermined if the percentage value of the position of the actuating element 14 detected in the first step S1 is greater than a predetermined threshold value.

[0032] However, if, in first step S1, it is detected that the position of the control element 14 has a percentage value that is less than a threshold value, then, instead of the acceleration torque in step S2, a deceleration torque MV is predefined in step S3 for the motor vehicle 1. The predefined deceleration torque MV is generated at least by the friction brake device 13 of the motor vehicle 1. Optionally, the drive engine 7 is also operated in generator mode to generate the deceleration torque MV.

[0033] In the following step S4 , the relative speed v of the motor vehicle 1 relative to the ground is detected. In the present case, the relative speed v of the vehicle body of the motor vehicle 1 relative to the ground is detected.

[0034] In the subsequent step S5, the deceleration torque MV predefined for the motor vehicle 1 is changed based on the percentage value of the position of the control element 14 that is less than the threshold value according to the detected relative speed v. Figure 2 One of the characteristic curves S1, S2, S3, and S4 shown in FIG. 1 changes a predetermined deceleration torque MV. This results in a particularly comfortable deceleration process for motor vehicle 1 . To ensure the change in deceleration torque MV, the deceleration torque MV generated by the friction brake device 13 , the generator-like deceleration torque MV generated by the drive engine 7 , or both the deceleration torque MV generated by the friction brake device 13 and the deceleration torque MV generated by the drive engine 7 can be optionally changed.

[0035] Since the friction brake device 13 can be actuated to generate a deceleration torque MV, the motor vehicle 1 can be decelerated to a standstill. Furthermore, the motor vehicle 1 can be held in a standstill by actuating the friction brake device 13 .

Claims

1. A method for operating a motor vehicle (1), comprising a drive assembly (6), a friction brake system (12), and an adjusting element (14), wherein the drive assembly comprises an electric drive machine (7), the friction brake system is a hydraulic friction brake system, and wherein: The adjusting element (14) is displaceable in a stepless manner between a first end state and a second end state, wherein the position of the adjusting element (14) in the first end state corresponds to a percentage value of 0% and the position of the adjusting element in the second end state corresponds to a percentage value of 100%, the method comprising the following steps: - when the position of the control element (14) has a percentage value greater than a predetermined threshold value, an acceleration torque is predetermined for the motor vehicle (1), - when the position of the control element (14) has a percentage value that is less than the threshold value, a deceleration torque (MV) is predetermined for the motor vehicle (1), - actuating the friction brake system (12) such that the friction brake system (12) at least partially generates the predetermined deceleration torque (MV), wherein a reference deceleration torque is generated by the friction brake system, which reference deceleration torque is greater or less than the predetermined deceleration torque, wherein the reference deceleration torque remains constant when the speed of the vehicle relative to the ground changes, wherein the difference between the reference deceleration torque and the predetermined deceleration torque (MV) is at least substantially compensated by operating the electric drive machine (7) as a motor or as a generator, In this case, the electric drive machine is operated as a motor when the reference deceleration torque is greater than a predefined deceleration torque, and the electric drive machine is operated as a generator when the reference deceleration torque is less than the predefined deceleration torque.

2. The method according to claim 1, characterized in that A relative speed (v) of the motor vehicle (1) relative to the ground is detected, and the predetermined deceleration torque (MV) is changed according to the detected relative speed (v).

3. The method according to claim 2, characterized in that When the relative speed (v) decreases, the predefined deceleration torque (MV) is reduced.

4. The method according to claim 3, characterized in that A first threshold speed (v1, v2) is predefined, wherein the predefined deceleration torque (MV) is reduced only when the detected relative speed (v) is less than the first threshold speed (v1, v2).

5. The method according to claim 4, characterized in that A second threshold speed (v3) is predetermined, the second threshold speed being greater than the first threshold speed (v2), wherein, when a relative speed (v) greater than the first threshold speed (v2) and less than the second threshold speed (v3) is detected, the predetermined deceleration torque (MV) is increased when the relative speed (v) decreases.

6. The method according to claim 1, characterized in that The deceleration torque (MV) is predetermined according to previously stored characteristic curves (S1, S2, S3, S4).

7. The method according to claim 6, characterized in that The characteristic curves (S1, S2, S3, S4) have a slope which increases and / or decreases as the relative speed (v) decreases.

8. The method according to claim 1, characterized in that The motor vehicle (1) is decelerated to a standstill by the predetermined deceleration torque (MV).

9. The method according to claim 1, characterized in that Minimum values (MV1, MV2) are predefined for the deceleration torque (MV).

10. The method according to claim 1, characterized in that The friction brake system (12) is actuated so that the friction brake system (12) fully generates the predetermined deceleration torque (MV).

11. A controller (15) for a motor vehicle (1), wherein: The motor vehicle (1) has a drive component (6), a friction brake system (12) and an adjusting element (14), the drive component having an electric drive machine (7), wherein the adjusting element (14) is displaceable in a stepless manner between a first end state and a second end state, wherein the position of the adjusting element (14) in the first end state corresponds to a percentage value of 0% and the position of the adjusting element (14) in the second end state corresponds to a percentage value of 100%, characterized in that the controller (15) is arranged to carry out the method according to any one of claims 1 to 10 during normal use.

12. A motor vehicle (1) comprising a drive assembly (6), a friction brake system (12) and an adjusting element (14), wherein the drive assembly comprises an electric drive machine (7), wherein: The regulating element (14) is capable of being shifted steplessly between a first end state and a second end state, wherein the position of the regulating element (14) in the first end state corresponds to a percentage value of 0% and the position of the regulating element (14) in the second end state corresponds to a percentage value of 100%, and is characterized by having a controller (15) according to claim 11.

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