Method for operating automobile, computer program product, storage medium, and computer mechanism

Abstract

To provide a method for activating an automobile.SOLUTION: At step S1, torque target value and rotating speed limit value relative to an actuator is set by a central control device in particular in accordance with an acceleration request or a brake request. At step S2, an adjustable range is set between the zero torque and the torque target value with respect to a generable torque to activate to satisfy the acceleration request or brake request. Simultaneously, rotation number actual value is detected and is compared with rotating speed limit value. At step S3, beyond the zero torque, torque limit value with a code different from the torque target value is activated within the adjustable range. Preferably, the adjustable range is provided only when the rotation number actual value deviates from the rotating speed limit value for prescribed tolerance or more.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for operating a motor vehicle, the motor vehicle having at least one axle and at least one wheel, to which a wheel brake device, in particular an electric machine, with an actuatable first actuator is associated, and to which a drive device, in particular an electric machine, with an actuatable second actuator is associated.

[0002] Furthermore, the invention relates to a computer program product, i.e., said computer program product implementing the above method when said computer program product is run on a computer arrangement, and further to a machine-readable storage medium comprising such a computer program product, and to a computer arrangement specially equipped for running said computer program product or for implementing said method. [Background technology]

[0003] It is known from the prior art to utilize an existing electric drive in an electrically driven vehicle or to use an electric drive in conjunction with or instead of a wheel brake system to slow the vehicle, whereby the drive intervention usually occurs with particularly low friction values ​​only up to complete or maximum deceleration, i.e., up to the maximum possible deceleration, which mainly involves fully utilizing the pre-determined physical limitations due to the roadbed. Summary of the Invention

[0004] A method according to the invention having the features of claim 1 comprises: setting at least one torque setpoint and a speed limit for an actuator depending on an acceleration or braking request; setting a first adjustment range for the torque that can be generated by a second actuator, the torque setpoint extending between zero torque and the torque setpoint; activating the second actuator within the first adjustment range to fulfill the acceleration or braking request; detecting an actual speed value and comparing it with the speed limit; if the comparison determines that the speed limit is exceeded in an acceleration request or that the speed limit is below the speed limit in a braking request, providing a second adjustment range extending beyond zero torque to a torque limit having a different sign from the torque setpoint; and activating the second actuator within the second adjustment range. Thus, according to the invention, an electric drive is first involved in a control task (acceleration or braking) by setting a torque setpoint in relation to the speed limit. As long as the actual rotational speed (actual rotational speed) occurring during a braking request is above a rotational speed limit (which then determines the minimum rotational speed) or below a rotational speed limit (which then determines the maximum rotational speed) during an acceleration request, the corresponding second actuator of the drive device only follows a predetermined torque. In particular, a first rotational speed limit for the braking request and a second rotational speed limit for the acceleration request are defined. For example, the torque target is activated during a braking request, and the torque generated is immediately reduced as soon as the rotational speed limit is reached or falls below the rotational speed limit, particularly by a control circuit. During the first adjustment range, the actuator can only differ from the torque target in the direction of zero torque. In this regard, if the torque target during a braking request is defined as a negative torque, the actuator can only reduce the braking torque but cannot apply a positive acceleration drive torque to raise the actual rotational speed of the wheel or axle back to the rotational speed limit. The rotational speed limit value for the braking demand is usually selected so that a locking tendency is excluded, so that below which there is a corresponding risk of the respective wheel locking.The torque target value here depends, inter alia, on the actuation of the operating device by the vehicle driver and / or the settings of the vehicle assistance system, e.g., on the actuation of the brake pedal, for example, within the scope of emergency braking. A similar limitation applies to acceleration requests. For example, the torque target value is activated during an acceleration request, thereby immediately reducing the torque generated if the rotational speed limit is reached or exceeded. While the first adjustment range is set, the actuator may only differ from the torque target value in the direction of zero torque. Therefore, if the torque target value during an acceleration request is defined as a positive drive torque, the actuator may only reduce the drive torque, but may not apply a negative braking torque to reduce the actual rotational speed of the wheel or axle below the rotational speed limit again. It is conceivable to activate the first actuator of the wheel brake system as an auxiliary. However, it should be noted that the scanning time of the brake control is usually longer than that of the drive control, and there is a time delay before the wheel brake system actually provides braking torque (the delay during the build-up of the torque and the delay until the brake linings contact the brake disc). In some cases, using the first adjustment range with the wheel brake system's assistance is sufficient in normal driving situations to ensure that any undershooting or overshooting of the predetermined speed limit is corrected again within a reasonable time. However, in driving situations, particularly those involving rapid changes in friction values ​​or sudden demands for high torque, it may happen that the speed setting is not maintained for a relatively long time. This can be explained by the fact that the electric drive's control circuit is initially limited to the first adjustment range and is therefore unable to apply a torque that would counteract the speed difference. Since the wheel brake device can only generate torque in the opposite direction to the direction of wheel movement, a negative braking torque is always generated when the wheel rotation speed is positive, i.e., the wheel brake device cannot be used to accelerate the wheel, but can only be used to decelerate the wheel.In the first adjustment range, only the longitudinal tire force is effective in accelerating the wheels. However, this force depends on the road surface and is very small, especially on road surfaces with low friction values. This limits the possible wheel acceleration and thus the time spent below the specified rotation speed. As mentioned above, braking is generally available for cases where wheel deceleration is necessary. However, this can potentially create mechanical strain on the powertrain if the braking application is not timed correctly, since drive and braking would otherwise provide opposing torques. This directly affects the vehicle's driving dynamics, particularly when braking or driving, and can result in a brief loss of steering and lateral stability. The present invention eliminates this situation, advantageously dramatically shortening the time during which the rotation speed follows the default rotation speed value. This significantly improves both steering and lateral stability in the aforementioned situations. The aforementioned advantages are achieved according to the present invention by providing a second adjustment range, which allows the application of a torque with a sign different from the currently active torque setpoint if the aforementioned deviation of the actual speed from the respective speed limit is recognized. As a result, the drive can also apply a positive drive torque when braking is requested and a negative braking torque when acceleration is requested. This occurs by correspondingly activating a second actuator within the second adjustment range. The second adjustment range is, in particular, a direct extension of the first adjustment range and / or complements it at least for a certain time. For example, a switch is made from the first adjustment range to a second adjustment range, which extends from the torque setpoint to the torque limit, i.e., including a change in sign. This activation is then performed in order to bring the actual speed back closer to the speed limit until it again exceeds the speed limit (braking request) or falls below the speed limit (acceleration request).

[0005] In a further advantageous embodiment of the invention, the actual wheel speeds of the wheels and / or the actual axle speeds of the axles are detected as the actual rotational speed values. This advantageously ensures that the drive is optimally coupled to the control task. Preferably, in the case of an axle drive, the actual axle speeds are detected, and in the case of a single-wheel drive, the actual wheel speeds are detected.

[0006] It is particularly advantageous to provide for the second adjustment range to be provided only if the actual speed value deviates from the speed limit value by more than a certain tolerance, which advantageously increases the efficiency of the method according to the invention, since even the slightest deviation, i.e., below or above, does not result in the second adjustment range being provided and a corresponding activation being applied.

[0007] According to a further advantageous embodiment of the invention, the second adjustment range is provided for a predetermined time. This advantageously ensures that driving safety is not impaired, for example, due to control malfunctions, since the corresponding exceeding or falling below zero torque is permitted only for a predetermined time. That is, only a brief expansion of the adjustment range into the positive range (braking request) or negative range (acceleration request), respectively, occurs, but this brief expansion must be reduced to the corresponding zero torque immediately after the predetermined time. In particular, the time is provided in the range of seconds or fractions of a second, for example, less than 0.5 seconds or less than 1 second.

[0008] It is particularly advantageous to provide that if a predetermined enabling signal is recognized within this time period, the provision of the second adjustment range is maintained beyond the predetermined time period. This has the advantage that the provision of the second adjustment range can be activated by an external enabling signal in order to ensure driving safety at all times. If an enabling signal is recognized, the corresponding torque does not have to be reduced to zero torque, but can be adjusted within the second adjustment range. For example, the corresponding enabling signal can be generated depending on the actual wheel slip and / or torque at each wheel.

[0009] According to an advantageous further configuration of the invention, it is provided that the enabling signal is generated by a control mechanism associated with the first actuator and / or by a central control device and transmitted to and / or received by the control mechanism of the second actuator, which advantageously ensures an independent, external generation and processing of the enabling signal, thereby further improving the security of the method according to the invention.

[0010] It is particularly advantageous to provide for the provision of the second adjustment range to be terminated once the actual speed value reaches at least the speed limit again, in particular if it exceeds the speed limit during a braking request or if it falls below the speed limit during an acceleration request, thereby further improving the efficiency of the method according to the invention, since the second adjustment range is only provided for a period that is also required to ensure driving stability.

[0011] According to a further advantageous embodiment of the invention, it is provided that the torque target value and / or the rotational speed limit value are set by a central control device, which provides a particularly advantageous possibility for setting a number of values ​​over a wide area of ​​the vehicle, so that the method according to the invention can be carried out correspondingly at each of the wheels involved in the motor vehicle.

[0012] It is particularly advantageous if each actuator is assigned its own control mechanism, which is in particular connected to a central control device in terms of communication technology, and in this case it is provided that each actuator is activated by its associated control mechanism. This respective individual control mechanism for each actuator has the advantage that the actuators can always be reliably activated independently of one another. Additionally, if such a central control device is provided, in particular as part of the brake system, an advantageous distributed concept results, in which a plurality of control mechanisms each form an activation part and the control device forms a part that provides a target value or limit value.

[0013] A computer program product according to the invention for execution on a computer arrangement with the features of claim 10 is characterized in that the computer program product, when used as specified, implements the method according to the invention, which results in the advantages already mentioned.

[0014] A machine-readable storage medium according to the invention with the features of claim 11 is characterized in that it has stored thereon a computer program product according to the invention.

[0015] A computer arrangement having the features of claim 12 is characterized in that it is specially equipped to run the computer program product according to the invention or to carry out the method according to the invention, which also results in the advantages already mentioned above. Preferably, the computer arrangement is a control device and / or a control arrangement associated with the motor vehicle, in particular arranged in the motor vehicle.

[0016] For example, a corresponding motor vehicle may have at least one axle with wheels, to which a wheel brake device, in particular an electric machine, with a first actuatable actuator is associated, and to which a drive device, in particular an electric machine, with a second actuatable actuator is associated, the motor vehicle being characterized in that it has at least one computer mechanism according to the invention configured as a central control device and / or at least one computer mechanism according to the invention configured as a control device associated with the actuator, from which the advantages already mentioned arise. Particularly advantageously, the motor vehicle has at least one first and one second wheel on an axle, in which the first wheel, in particular on the left side of the motor vehicle, is provided with a first wheel brake device with an actuatable first actuator, in particular an electric machine, and the second wheel, in particular on the right side of the motor vehicle, is provided with a second wheel brake device with another actuatable first actuator, in particular an electric machine, and the wheels are provided with a common drive with one actuator or with one actuatable second actuator in each case, or with a separate drive, in particular an electric machine, for each of the wheels. From this also arises the advantages already mentioned.

[0017] Further advantageous features and feature combinations are apparent from the foregoing description and the claims.The invention will now be explained in more detail with the aid of the drawings. [Brief explanation of the drawings]

[0018] [Figure 1] 1 illustrates advantageous vehicle components; [Figure 2] FIG. 1 illustrates a method for operating a vehicle. [Figure 3] 10 is a progress graph during a braking request. DETAILED DESCRIPTION OF THE INVENTION

[0019] 1 shows, only in a schematic representation, the components of an advantageous vehicle 1 and how they are interconnected. The vehicle 1 has at least one, and preferably two, axles 2, which are not directly visible in the figure. The axle 2 has a first wheel 3 attached to the left side of the vehicle 1 and a second wheel 4 attached to the right side of the vehicle 1.

[0020] A first wheel brake device 5 is provided on the first wheel 3, which includes an actuatable first actuator 6, which in this embodiment is implemented as an electric machine. A second wheel brake device 7 is provided on the second wheel 4, which includes another actuatable first actuator 8, which in this embodiment is also implemented as an electric machine. The wheel brake devices 5, 7 and the actuators 6, 8 are designed identically in this embodiment. Therefore, only one of the wheel brake devices 5, 7 with its respective actuator 6, 8 is illustrated in FIG. 1.

[0021] Furthermore, in this embodiment, the wheels 3, 4 are assigned a common drive 9 which acts on the respective wheels 3, 4 via the axle 2, in particular via an open differential, and for this purpose the drive 9 has an actuatable second actuator 10 which is designed as an electric machine.

[0022] A control assembly 11 is further provided for actuating the actuators 6, 8, 10. The control assembly 11 comprises a central control device 12 and a plurality of control mechanisms 13, 14, 15 communicatively coupled thereto, each of which is assigned to exactly one of the actuators 6, 8, 10 in order to actuate the respective actuator 6, 8, 10. In this regard, a first control mechanism 13 is assigned to the first actuator 6, another first control mechanism 14 is assigned to the other first actuator 8, and a second control mechanism 15 is assigned to the second actuator 10.

[0023] The central control device 12 is configured to set specific values ​​for the control devices 13, 14, 15, which are subordinate to it, and depending on these values, the control devices 13, 14, 15 activate the corresponding actuators 6, 8, 10. In the present embodiment, the central control device 12 is configured to set a torque target value and a speed limit value. The control devices 13, 14, 15 are configured to perform speed control by correspondingly activating the actuators 6, 8, 10 depending on the current wheel speed or wheel speed or axle speed or axle speed, as indicated by the corresponding arrows.

[0024] An advantageous method for operating the motor vehicle 1 will now be described with reference to Figure 2. For this purpose, Figure 2 shows the method on the basis of a flow chart. In particular, the method ensures that the drive unit 9 is always optimally coupled to the control tasks for satisfying acceleration or braking requests. The method will be described using the example of wheel control for one of the wheels 3, 4, which is implemented by means of the control assembly 11, as already mentioned above.

[0025] In step S1, the method begins with setting at least one torque target and speed limit for the actuators 6, 8, 10, in particular by the central control device 12, as a function of the acceleration or braking request.

[0026] In step S2, a first adjustment range extending between zero torque and the torque target value is set for the torque that can be generated by the second actuator 10, and the second actuator 10 is activated to satisfy the acceleration or braking request within the first adjustment range. In parallel, the actual rotational speed value is detected and compared with the rotational speed limit value. In this embodiment, the drive unit 9 is attached to the axle 2 as an axle drive, so the actual axle rotational speed of this axle is detected as the rotational speed actual value.

[0027] If the comparison determines that the rotational speed limit is exceeded during an acceleration request or is below during a braking request, the method continues with step S3.

[0028] In step S3, a second adjustment range is provided which extends beyond zero torque to a torque limit value which has a different sign from the torque target value, and the second actuator 10 is then activated within the second adjustment range. Preferably, the second adjustment range is provided only if the actual speed value deviates from the speed limit value by more than a predetermined tolerance, in particular if these values ​​deviate from each other in terms of a relative or absolute deviation, and / or if a predetermined time has elapsed.

[0029] The second adjustment range is initially provided for a predetermined time, and the provision of the second adjustment range beyond the predetermined time is maintained only if a predetermined enabling signal is recognized within this time. The enabling signal is generated in particular by a control mechanism 13, 14 associated with each first actuator 6, 8 and / or by a central control device 12 and sent to and / or received by a control mechanism 15 of the second actuator 10.

[0030] The method ends in step S4, in which the provision of the second adjustment range is terminated when the actual rotational speed value reaches at least the rotational speed limit value again, in particular when the rotational speed limit value is exceeded in the event of a braking request or when it falls below the rotational speed limit value in the event of an acceleration request.

[0031] 3 shows corresponding time courses that can occur during a braking request, with a first variant showing no implementation of the method, a second variant showing early termination of the second adjustment range, and a third, particularly advantageous variant showing full implementation of the method and the resulting advantages. The application during an acceleration request is carried out correspondingly as already explained above.

[0032] The first (upper) of the four graphs firstly shows the dual course of when the corresponding control or activation A of the actuator 10 begins within the first adjustment range. It can be seen that this occurs at time t1.

[0033] The second of the four graphs, located below, plots the torque curves for the torque generated by the actuator 10 for each of the three previously mentioned variations. The torque M1 is plotted for the first variation without the method, the torque M2 for the second variation with only partial application of the method, and the torque M3 for the third variation with full application of the method. All torques start as negative braking torques. At time t1, these torques increase towards zero torque.

[0034] This occurs when the corresponding actual value of the axle speed (the course of which is shown in the third of the four graphs below) is equal to the corresponding speed limit value n G This is because the following occurs: The operation at this time corresponds to a sudden change in friction value during deceleration.

[0035] In the first variant, the actual value n1 drops most sharply and then the actual value n1 again approaches the rotational speed limit value n G Despite the early start of the control, the axle speed is clearly below the predetermined speed limit and remains in this range for a very long time, with considerable negative effects on steering and stability.

[0036] In the second variant, a second adjustment range is provided, and the actual value n2 is somewhat suppressed by the torque M2 becoming positive for at least a predetermined time Δt until a second time t2, i.e., acting as a drive torque and again accelerating the corresponding wheel somewhat. G , but this nevertheless continues for a fairly long time.

[0037] This means that only a time-limited, independent adjustment range expansion is utilized here: the positive torque already reduces the chance of the engine speed falling below the limit value, but if a permanent expansion does not occur, the remaining deviations will remain for some time.

[0038] Rotation speed limit value n G The smallest drop and the quickest re-achievement or re-exceedance also occurs in the third variant, where an enabling signal is received and the second adjustment range is provided over the time Δt or beyond the second point in time t2, and the actual value n3 rises again more quickly, since the corresponding torque M3 remains positive for a correspondingly longer period.

[0039] Here, the method is fully applied and the rotational speed limit value n G In this variant, the enable signal for a permanent adjustment range extension reaches the speed controller in time in order to maintain the extended adjustment range. The speed can then be returned to the speed limit very quickly.

[0040] The fourth (lower) of the four graphs further illustrates the corresponding dual course of the enabling signal in the second or third variant, i.e. in the second variant, as already mentioned, no enabling signal is received, so that the corresponding course F2 remains near zero and correspondingly the provision of the second adjustment range ceases at time t2.

[0041] Only in the third variation does the enabling signal be received exactly in time at the instant t2, so that the corresponding curve F3 has a positive value, providing an even wider second adjustment range, at least while the enabling signal is received. [Explanation of symbols]

[0042] 1. Automobiles 2 axles 3 First (left) wheel 4 Second (right) wheel 5 First wheel brake device 6 First Actuator 7 Second wheel brake device 8 Other first actuator 9 Drive unit 10 Second Actuator 13 First Control Mechanism 14 Other primary control mechanisms 15 Second Control Mechanism n G Rotation speed limit

Claims

1. A method for operating a motor vehicle (1), comprising: - said vehicle (1) has at least one axle (2) and at least one wheel (3, 4); - the wheels (3, 4) are provided with wheel braking devices (5, 7) with actuatable first actuators (6, 8), in particular electric machines; - the wheels (3, 4) are provided with a drive (9) with a second actuator (10) that can be activated, in particular an electric machine, In the method, - at least one torque target and a rotational speed limit (n Ｇ ) and setting - setting a first adjustment range for the torque that can be generated by said second actuator (10), said adjustment range extending between zero torque and said torque target value; - activating said second actuator (10) to satisfy an acceleration or braking request within said first adjustment range; - Detecting the actual rotation speed value and setting the rotation speed limit value (n Ｇ ) and compare it with - the comparison determines the rotational speed limit value (n Ｇ ) or when a braking request is made, the rotational speed limit value (n Ｇ providing a second adjustment range extending beyond the zero torque to a torque limit value having a different sign than the torque target value, and then activating the second actuator (10) within the second adjustment range; A method characterized by:

2. 2. The method according to claim 1, wherein the actual rotational speed values ​​are the actual wheel rotational speed values ​​of the wheels (3, 4) and / or the actual axle rotational speed value of the axle (2).

3. When the actual rotation speed value exceeds a predetermined tolerance, the rotation speed limit value (n Ｇ 3. The method according to claim 1, wherein the second adjustment range is provided only if the first adjustment range deviates from the first adjustment range.

4. 4. The method according to claim 1, wherein the second adjustment range is provided for a predetermined time.

5. 5. The method of claim 4, further comprising maintaining provision of said second adjustment range beyond said predetermined time if a predetermined enabling signal is recognized within said time.

6. 6. The method according to claim 5, characterized in that the enabling signal is generated by a control mechanism (13, 14) associated with the first actuator (6, 8) and / or by a central control device (12) and transmitted to and / or received by the control mechanism (15) of the second actuator (10).

7. The actual rotation speed value is the rotation speed limit value (n Ｇ ) is reached again, in particular in the event of a braking request. Ｇ ) or when acceleration is required, the rotation speed limit value (n Ｇ 7. The method according to claim 1, further comprising terminating the provision of the second adjustment range if the difference between the first and second adjustment ranges is less than the first adjustment range.

8. The torque target value and / or the rotational speed limit value (n Ｇ 8. The method according to claim 1, wherein the temperature is set by a central control unit (12).

9. 9. The method according to claim 1, wherein each of the actuators (6, 8, 10) is associated with its own control mechanism (13, 14, 15), which is in particular connected in communication with a central control device (12), and each of the actuators (6, 8, 10) is activated by its associated control mechanism (13, 14, 15).

10. A computer program product for execution on a computer mechanism, characterized in that said computer program product, when used as specified, performs the method of any one of claims 1 to 9.

11. A machine-readable storage medium comprising the computer program product of claim 10.

12. A computer arrangement, in particular an electronic control unit (12) and / or control unit (13, 14, 15) for a motor vehicle, characterized in that the computer arrangement is specially equipped to implement a computer program product according to claim 10.

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