Method for operating motor vehicle, motor vehicle and computer program product
By adjusting the braking force distribution of the front and rear wheels in the braking system of the motor vehicle, the noise problem caused by steering control during parking is solved, and a better NVH characteristic and driving experience is achieved.
Patent Information
- Application Number
- CN202380053652.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-07-26
- Filing Date
- 2023-06-01
- Publication Date
- 2025-02-28
AI Technical Summary
During the parking process of a motor vehicle, the stress changes caused by steering can cause noise and interfere with the driving experience.
The brake system is controlled by a data processing device and the braking force distribution of the front and rear wheels is adjusted to reduce noise during tension release. The specific method is to adapt the braking force distribution when specific conditions are met, so that the front braking force component is reduced and the rear braking force component is increased, thereby reducing the occurrence of tension and the generation of noise.
It effectively reduces the noise of the motor vehicle when steering at stationary or low speed, improves the NVH characteristics, and improves the driving experience.
Smart Images
Figure CN119546495A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a method for operating a motor vehicle. The invention also relates to a motor vehicle and a computer program product. Background Art
[0002] During the parking process of a motor vehicle, steering maneuvers are usually carried out at low speed. These steering maneuvers can cause stresses in the chassis components of the motor vehicle (axles, control arms, brakes, tires), for example due to the axle geometry and the steering wheel radius. This is especially true when the steering maneuvers are carried out at a standstill and / or when the brakes are actuated. If the brakes are subsequently released and / or the vehicle is set in motion, the stresses are reduced again. However, the reduction in stresses often leads to noises in the vehicle, which are often perceived as disturbing. Summary of the invention
[0003] The object of the present invention is to provide an advantageous method for operating a motor vehicle. The object of the present invention is also to provide an advantageously designed motor vehicle and an advantageous computer program product.
[0004] These objects are achieved by a method having the features of claim 1, a motor vehicle having the features of claim 9 and a computer program product having the features of claim 10. The advantages and preferred embodiments described with respect to the method can also be appropriately transferred to the device, i.e. to the computer program product and the motor vehicle, and vice versa. Advantageous embodiments of the invention with appropriate improvements are described in the dependent claims.
[0005] The method according to the invention serves to operate a motor vehicle according to the invention, whereas the motor vehicle according to the invention is configured to carry out the method according to the invention in at least one operating mode.
[0006] The motor vehicle according to the invention has at least two axles, namely a front axle and a rear axle. The front axle is preferably designed as a steered front axle and the rear axle is preferably designed as a driven steered rear axle or a non-steered rear axle. In addition, the motor vehicle, namely the motor vehicle according to the invention, has a brake system with at least four wheel brakes, namely two front wheel brakes arranged on the front axle and two rear wheel brakes arranged on the rear axle. In addition, the motor vehicle has a data processing device, which is provided in particular for controlling the brake system.
[0007] During the execution of the method, i.e. the method according to the invention, a braking force distribution is then specified by the data processing device. In this case, a front braking force component / share / ratio is specified for the front wheel brake and a rear braking force component is specified for the rear wheel brake by the braking force distribution. The braking force components, i.e. the front braking force component and the rear braking force component, determine the proportion in which the front wheel brake and the rear wheel brake contribute to the total braking force generated by the wheel brakes of the braking system during the braking process.
[0008] In particular, the braking system is controlled or regulated in such a way that a total braking force is generated based on or in accordance with a braking request. The total braking force is composed of the partial braking forces generated by the individual wheel brakes. The wheel brakes are controlled in such a way that a given braking force distribution is achieved, wherein the front wheel brakes contribute to the total braking force in accordance with a front braking force component and the rear wheel brakes contribute to the total braking force in accordance with a rear braking force component.
[0009] Furthermore, during the method, if the data processing device determines that a given condition for acoustically perceptible release of tension is met in the motor vehicle, the braking force distribution is adapted to improve the NVH behavior of the motor vehicle. The braking force distribution is adapted based on the basic braking force distribution in such a way that the front braking force component is reduced and the rear braking force component is increased.
[0010] This ensures that tensions in the motor vehicle, in particular tensions of the type mentioned at the outset, occur less frequently and / or are less noticeable. Accordingly, the typical noises that are usually perceptible when the corresponding tension is released occur less frequently and / or are less noticeable, so that the noises are perceived as less disturbing. This improves the so-called NVH properties of the motor vehicle. NVH (Noise-Vibration-Harshness) stands for Noise-Vibration-Harshness and refers to acoustically and / or haptically perceptible vibrations that may occur in a motor vehicle.
[0011] Preferably, the braking force distribution is adapted independently of the braking request. The adaptation is therefore preferably carried out in a control device of the braking system, for example in a control program. The adaptation is carried out as soon as a given condition is met. However, the generation of the total braking force taking into account the adapted braking force distribution is only carried out when a braking request is also generated, for example when the driver presses the brake pedal or when an assistance function generates a braking command, for example an assistance function for implementing an automated or partially automated driving function.
[0012] Independently therefrom, during the method, the adaptation of the braking force distribution is preferably also canceled if the data processing device determines that the given condition is no longer met. The adaptation of the braking force distribution is therefore usually time-limited. The adaptation of the braking force distribution is always carried out when the given condition is met, and the adaptation of the braking force distribution is always canceled when the given condition is no longer met.
[0013] It is also expedient if the braking force distribution specifies only basic values for the braking force components. Based on these basic values, the wheel brakes are then controlled, preferably in a manner that allows deviations from these basic values, for example to implement an ABS system (anti-lock braking system) or driving dynamics control (ESC: electronic stability control). Alternatively, the braking force components are specified in a fixed manner.
[0014] Independently of this, a given condition may consist of two or more sub-conditions, depending on the application. In this case, the given condition is only met if all given sub-conditions are met.
[0015] Furthermore, the following embodiment of the method is advantageous: at least one of the given conditions or subconditions is satisfied if the speed of the motor vehicle is less than or equal to a given limit value. Depending on the application, the limit value is preferably in the range between 10 km / h and 60 km / h, further preferably in the range between 20 km / h and 60 km / h, in particular in the range between 30 km / h and 60 km / h.
[0016] Embodiments of the method are also expedient in which at least one of the given conditions or subconditions is met if the steering deflection angle or the steering angle exceeds a given limit value.
[0017] Furthermore, a method variant is also preferred in which the trajectory of the motor vehicle is determined by the data processing device in at least one operating mode. In this case, the data processing device is then usually configured to implement an assistance function for autonomous vehicle guidance or for partially autonomous vehicle guidance, wherein in the at least one operating mode, the vehicle guidance is performed by the assistance function based on the determined trajectory.
[0018] It is then further preferred in this case that at least one of the given conditions or sub-conditions is satisfied if the slope of the above-mentioned trajectory is greater than or equal to a given limit value.
[0019] According to another embodiment variant, alternatively or additionally, at least one of the given conditions or sub-conditions is satisfied if the curvature of the above-mentioned trajectory is greater than or equal to a given limit value.
[0020] Furthermore, an embodiment variant is advantageous in which at least one of the given conditions or subconditions is met if, based on the above trajectory determination, a steering angle greater than or equal to 15° and in particular greater than 20° is temporarily required.
[0021] Furthermore, embodiments of the method are expedient in which at least one of the given conditions or subconditions is met when one of the above-mentioned assistance functions (eg a parking assistance function or a parking assistance function) is activated.
[0022] Furthermore, the following method variant is also advantageous: the slope, i.e. the slope in the local terrain, is determined by the data processing device, and at least one of the given conditions or subconditions is satisfied if the slope is greater than or equal to a given limit value. Depending on the application, the limit value for the slope is in the range between 2% and 15%, more preferably in the range between 4% and 12%, in particular in the range between 6% and 10%.
[0023] It is further advantageous to adapt the braking force distribution as a function of the speed of the motor vehicle by gradually reducing the front braking force component as the speed decreases and gradually increasing the rear braking force component as the speed decreases. In other words, it is not simply switched back and forth between two different braking force distributions, but rather a gradual redistribution, so that in this case it is expedient to perform the opposite redistribution again when the speed of the motor vehicle increases.
[0024] Furthermore, the following method variant is also preferred: the braking force distribution is adapted so that the front braking force component is reduced to 0% or to approximately 0%, while the rear braking force component is increased to 100% or to approximately 100%. In other words, the braking force distribution is adapted so that the front wheel brakes are not used at least in a given speed range.
[0025] The braking force is then preferably distributed to the rear axle, at least when there is a braking demand, and no braking force is applied to the front axle. In a hydraulic brake system, the braking force is distributed to the rear axle, for example, by closing an inlet valve in the brake line of the front axle. By opening the outlet valve as required to discharge the brake fluid volume into the brake fluid container, the existing brake pressure on the front axle can be reduced and lowered. The reduced braking force on the front axle is compensated by increasing the braking force on the rear axle, for example by increasing the brake pressure on the rear axle. In this state, the required braking force is provided entirely by the rear axle, as long as the friction coefficient between the tire and the road surface permits. Otherwise, the established braking force distribution, i.e. the basic braking force distribution, is redistributed. Since the front wheels of the front axle are not braked in this state, the front wheels can roll freely during the steering process even when stationary, without tensioning occurring, which would have to be released with a perceptible noise in the event of a reduction in the braking force.
[0026] The method according to the invention described above is designed to be carried out in a motor vehicle according to the invention or by a motor vehicle according to the invention. Conversely, the motor vehicle according to the invention is configured to carry out the corresponding method in at least one operating mode. The motor vehicle has the aforementioned braking system and the aforementioned data processing device. With the aid of the data processing device, the individual steps of the method or at least a plurality of steps of the method are then preferably carried out, for which purpose it is further preferred that an executable program is stored or installed in the data processing device, which program automatically carries out the method or a plurality of steps of the method after starting.
[0027] If a suitable brake system and a suitable data processing device are already present in the motor vehicle, the corresponding program can also be installed or stored later with the aid of a computer program product according to the invention. The computer program product is usually a file or a data carrier with a file containing an executable program, ie, in particular a suitable program code.
[0028] It should be pointed out again that the advantages and preferred embodiments mentioned with respect to the method can also be appropriately transferred to the device, ie to the computer program product and the motor vehicle, and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Further advantages, features and details of the invention are apparent from the claims, the following description of preferred embodiments and in conjunction with the schematic drawings. The drawings show:
[0030] Figure 1 A motor vehicle is shown in a block diagram. DETAILED DESCRIPTION
[0031] The following is exemplarily described and Figure 1 The motor vehicle 2 schematically shown in FIG. 1 has two axles 4 , 6 , namely a front axle 4 and a rear axle 6 . In this case, the front axle 4 is designed as a steered front axle 4 and the rear axle 6 is designed as a non-steered rear axle 6 .
[0032] Furthermore, the motor vehicle 2 has a brake system 8 which has two front wheel brakes 10 arranged on the front axle 4 and two rear wheel brakes 12 arranged on the rear axle 6 .
[0033] The motor vehicle 2 also has a data processing device 14, which is provided in particular for controlling the brake system 8, and a sensor device 16, which is connected to the data processing device 14 for signaling. In this exemplary embodiment, the data processing device 14 is provided to execute the method explained in more detail below in at least one operating mode.
[0034] During the execution of the method, a braking force distribution is specified by the data processing device 14. In this case, the braking force distribution specifies a front braking force component for the front wheel brake 10 and a rear braking force component for the rear wheel brake 12. The braking force components, i.e. the front braking force component and the rear braking force component, determine the proportion in which the front wheel brake 10 and the rear wheel brake 12 contribute to the total braking force generated by the wheel brakes 10, 12 of the brake system 8 during the braking process.
[0035] Furthermore, during the method, if it is determined by the data processing device 14 that a given condition for acoustically perceptible stress relief in the motor vehicle 2 is met, the braking force distribution is adapted to improve the NVH behavior of the motor vehicle 2. In this case, the braking force distribution is adapted based on the basic braking force distribution, so that the front braking force component is reduced and the rear braking force component is increased.
[0036] Furthermore, during the method, if the data processing device 14 determines that the given condition is no longer met, the adaptation of the braking force distribution is canceled. Thus, the adaptation of the braking force distribution is performed as required. The adaptation of the braking force distribution is always performed when the given condition is met and is always canceled when the given condition is no longer met.
[0037] A method variant is preferred in which the braking force distribution is adapted so that the front braking force component is reduced to 0% or to approximately 0%, while the rear braking force component is increased to 100% or to approximately 100%. In other words, the braking force distribution is adapted so that the front wheel brake 10 is not used at least in a given speed range.
[0038] In this embodiment, the given condition is further satisfied if the speed of the motor vehicle 2 is less than or equal to a given limit value. The limit value is preferably in the range between 30 km / h and 60 km / h. The sensor device 16 is used to determine the speed of the motor vehicle 2.
[0039] According to an alternative method variant, data processing device 14 is configured to implement an assistance function for an autonomous parking process, namely a parking assistance function. Here, when the assistance function is activated, the trajectory of motor vehicle 2 is determined by data processing device 14 based on sensor data of sensor device 16 .
[0040] In this case, if the slope of the trajectory is greater than or equal to a given limit, the given condition is further satisfied. According to another embodiment, alternatively or additionally, in addition to the slope, if the curvature of the trajectory is greater than or equal to a given limit, the given condition is satisfied.
[0041] List of reference numerals:
[0042] 2Motor Vehicles
[0043] 4Front axle
[0044] 6 Rear axle
[0045] 8Brake system
[0046] 10 Front wheel brake
[0047] 12 Rear brake
[0048] 14 Data processing device
[0049] 16 Sensor device
Claims
1. A method for operating a motor vehicle (2), the motor vehicle having at least two axles (4, 6), namely a front axle (4) and a rear axle (6), the motor vehicle having a brake system (8), the brake system (8) having at least four wheel brakes, namely two front wheel brakes (10) arranged on the front axle (4) and two rear wheel brakes (12) arranged on the rear axle (6), the motor vehicle having a data processing device (14), wherein: - giving a force distribution by means of a data processing device (14), - by means of the braking force distribution, a front braking force component is given to the front wheel brake (10) and a rear braking force component is given to the rear wheel brake (12), - if it is determined by means of the data processing device (14) that a given condition for acoustically perceptible stress relief in the motor vehicle (2) is met, the braking force distribution is adapted to improve the NVH properties of the motor vehicle (2), The braking force distribution is adapted by reducing the front braking force component and increasing the rear braking force component.
2. The method according to claim 1, characterized in that This adaptation of the braking force distribution takes place independently of the braking request.
3. The method according to claim 1 or 2, characterized in that: The given condition is met if the speed of the motor vehicle (2) is less than or equal to a given limit value, the limit value being in the range of 15 km / h to 60 km / h.
4. The method according to any one of claims 1 to 3, characterized in that The trajectory of the motor vehicle (2) is determined by a data processing device (14), and a given condition is satisfied if the slope of the trajectory is greater than or equal to a given limit value.
5. The method according to any one of claims 1 to 4, characterized in that The trajectory of the motor vehicle (2) is determined by means of a data processing device (14), and a given condition is satisfied if the curvature of the trajectory is greater than or equal to a given limit value.
6. The method according to any one of claims 1 to 5, characterized in that The gradient in the local terrain is determined by means of a data processing device (14), and a given condition is satisfied if the gradient is greater than or equal to a given limit value.
7. The method according to any one of claims 1 to 6, characterized in that The braking force distribution is adapted as a function of the speed of the motor vehicle (2) by gradually reducing the front braking force component as the speed decreases and gradually increasing the rear braking force component as the speed decreases.
8. The method according to any one of claims 1 to 7, characterized in that The braking force distribution is adapted in such a way that the front braking force component is reduced to 0% and the rear braking force component is increased to 100%.
9. A motor vehicle (2) which is configured to carry out the method according to any one of the preceding claims in at least one operating mode.
10. A computer program product comprising a program executable on a data processing device (14) which, after being started, automatically executes the method according to any one of the preceding claims.