Rack end protection method for an electric power steering system and vehicle

Abstract

The present application relates to the technical field of vehicle, especially to a rack end protection method of electric power steering system and vehicle. The rack end protection method of electric power steering system comprises the following steps: obtaining a first angle of target steering wheel rotation; judging whether the first angle is greater than a second angle and less than a third angle; when the first angle is greater than the second angle and less than the third angle, judging whether the vehicle is in a first condition; when the vehicle is in the first condition, the target steering wheel rotation speed is a first set value; the first set value decreases with the increase of the first angle. When the first angle is greater than the second angle and less than the third angle, the target steering wheel rotation speed is the first set value, and the first set value decreases with the increase of the first angle, which can avoid the rack impacting the limiting device of the electric power steering system at a great speed, so as to realize the protection of the rack end.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicles, in particular to a rack end protection method of an electric power steering system and a vehicle. BACKGROUND

[0002] Vehicles are mainly used for carrying passengers and / or goods, and with the development of economy and technology, vehicles are widely used. In the field of vehicle technology, an electric power steering system is usually used, which is a power steering system that directly relies on an electric motor to provide auxiliary torque, and basically has a rack end protection function. The basic principle of the rack end protection function is that when the rack in the steering gear is about to reach the end of the rack, the motor current is limited to reduce the motor assistance, thereby reducing the speed of the driver turning the steering wheel, playing a buffering role, reducing the impact force of the rack end, reducing mechanical wear and tear, and prolonging the service life of the electric power steering system. However, the electric power steering system in the prior art has the defect that the rack end protection effect is poor, which further leads to a short service life of the electric power steering system. SUMMARY

[0003] Therefore, the present application aims to provide a rack end protection method of an electric power steering system to solve or partially solve the problem of poor rack end protection effect of the existing electric power steering system.

[0004] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0005] A rack end protection method of an electric power steering system, comprising the following steps,

[0006] obtaining a first angle of target steering wheel rotation;

[0007] determining whether the first angle is greater than a second angle and less than a third angle;

[0008] when the first angle is greater than the second angle and less than the third angle, determining whether the vehicle is in a first condition;

[0009] when the vehicle is in the first condition, the target steering wheel rotation speed is a first set value;

[0010] the first set value decreases as the first angle increases.

[0011] Further, from the second angle to the third angle, a plurality of first set values are arranged in a straight line.

[0012] Further, the second angle is a rack end protection limit start angle; and / or,

[0013] The third angle is a soft stop point angle of the vehicle.

[0014] Further, the first condition includes that a torque direction of the target steering wheel is same as a turning angle direction of the target steering wheel, a vehicle speed of the vehicle is less than a calibration value, and a turning angle signal of the target steering wheel is normal.

[0015] Further, the target steering wheel turning speed is related to the electric power steering assistance, and in the step of determining that the vehicle is in the first condition, the target steering wheel turning speed is a first set value.

[0016] The electric power steering assistance is adjusted so that the target steering wheel turning speed is the first set value.

[0017] Further, after the step of obtaining the first angle of the target steering wheel turning, the method further comprises the steps of:

[0018] Determining whether the first angle is greater than the third angle.

[0019] When the first angle is greater than the third angle, determining whether the driver intervenes in the steering wheel turning.

[0020] When the driver does not intervene in the steering wheel turning, determining whether the vehicle is in a second condition.

[0021] When the vehicle is in the second condition, the target steering wheel is turned back to the third angle.

[0022] Further, the step of determining whether the driver intervenes in the steering wheel turning comprises:

[0023] Obtaining a target steering wheel torque T.

[0024] Determining whether the target steering wheel torque T is less than T1.

[0025] When the target steering wheel torque T is less than T1, determining whether the target steering wheel torque T being less than T1 lasts for a first time and a target steering wheel torque descending slope exceeds A.

[0026] When the target steering wheel torque T being less than T1 lasts for the first time and the target steering wheel torque descending slope exceeds A, it is determined that the driver does not intervene in the steering wheel turning.

[0027] When the target steering wheel torque T is not less than T1, determining whether the target steering wheel torque T is greater than T2, wherein T2 is greater than T1.

[0028] When the target steering wheel torque T is greater than T2, determining whether the target steering wheel torque T being greater than T2 lasts for a second time.

[0029] When the target steering wheel torque T is greater than T2 for a second time, it is determined that the driver intervenes in the steering wheel rotation.

[0030] Further, the second condition includes that the vehicle speed of the vehicle is less than a designated value, and the target steering wheel rotation angle signal is normal.

[0031] Further, after the step of determining whether the driver intervenes in the steering wheel rotation according to the first angle being greater than the third angle, the method further comprises the steps of:

[0032] When the driver intervenes in the steering wheel rotation, it is determined whether the vehicle is in the second condition.

[0033] When the vehicle is in the second condition, the target steering wheel rotation speed is a second set value, and the second set value is the minimum value in the first set value.

[0034] Compared with the prior art, the rack end protection method of the electric power steering system has the following advantages:

[0035] The rack end protection method of the electric power steering system of the present application, when the first angle of the target steering wheel rotation is greater than the second angle and less than the third angle, and the vehicle is in the first condition, the rack end protection is limited; at this time, the target steering wheel rotation speed is a first set value, and the first set value decreases with the increase of the first angle, which can avoid the rack impacting the limiting device of the electric power steering system at a large speed, so as to realize the protection of the rack end.

[0036] Another object of the present application is to provide a vehicle to solve or partially solve the problem of short service life of the existing vehicle electric power steering system.

[0037] To achieve the above object, the technical scheme of the present application is as follows:

[0038] A vehicle comprises,

[0039] A steering wheel angle detection module is configured to obtain the rotation angle of a target steering wheel.

[0040] A vehicle state acquisition module is configured to obtain the state of the vehicle, and the state of the vehicle includes a first condition.

[0041] An electric power steering system is configured to provide electric power steering assistance for the rotation of the target steering wheel.

[0042] A steering wheel rotation control module is configured to control the electric power steering assistance of the electric power steering system according to the rotation angle of the target steering wheel and the state of the vehicle, so that the target steering wheel rotation speed is a first set value.

[0043] Further, the vehicle further comprises a steering wheel torque detection module configured to acquire a torque of the target steering wheel, and the state of the vehicle further comprises a second condition; and the steering wheel rotation control module is configured to control the electric power steering system according to the rotation angle of the target steering wheel, the torque of the target steering wheel and the state of the vehicle, so that the target steering wheel is rotated to a third angle.

[0044] The rack end protection method of the electric power steering system of the vehicle has the same advantages as the rack end protection method of the electric power steering system of the prior art, and will not be described here. BRIEF DESCRIPTION OF DRAWINGS

[0045] The accompanying drawings, which form a part of the disclosure, are intended to provide further understanding of the present disclosure and are incorporated herein for explanatory purposes. The illustrative embodiments of the present disclosure and their description serve the purpose of explanations and are not limiting on the present disclosure. In the drawings:

[0046] Figure 1 A flowchart of the rack end protection method of the electric power steering system of the embodiment of the present disclosure;

[0047] Figure 2 A flowchart of judging whether the driver intervenes in the rotation of the steering wheel of the embodiment of the present disclosure;

[0048] Figure 3 A structural connection diagram of the vehicle of the embodiment of the present disclosure;

[0049] Figure 4 A target steering wheel speed MAP diagram of the embodiment of the present disclosure.

[0050] Explanation of reference signs:

[0051] 1 - steering wheel angle detection module; 2 - vehicle state acquisition module; 3 - steering wheel rotation control module; 4 - electric power steering system; 5 - steering wheel torque detection module. DETAILED DESCRIPTION

[0052] It should be noted that the embodiments in the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0053] The present disclosure will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0054] Reference Figure 1 As shown in the drawings, an embodiment of the present disclosure provides a rack end protection method of an electric power steering system, comprising the following steps:

[0055] S01, acquiring a first angle of rotation of a target steering wheel;

[0056] S02, determining whether the first angle is greater than the second angle and less than the third angle;

[0057] S03, when the first angle is greater than the second angle and less than the third angle, determining whether the vehicle is in a first condition;

[0058] S04, when the vehicle is in the first condition, the target steering wheel rotation speed is a first set value; wherein the first set value decreases with the increase of the first angle.

[0059] It can be understood that the third angle is greater than the second angle.

[0060] The rack end protection method of the electric power steering system in the embodiment of the application can avoid the rack from impacting the limiting device of the electric power steering system 4 at a great speed, so as to realize the protection of the rack end.

[0061] In actual use, for example, when the target steering wheel is subjected to a large torque, or the vehicle is located on a road surface with small friction force, and the first angle is greater than the second angle and less than the third angle, and the vehicle is in the first condition, the target steering wheel rotation speed is still the first set value, which can effectively avoid the rack from impacting the limiting device of the electric power steering system 4 at a great speed, so as to realize the protection of the rack end.

[0062] In actual application, in step S01, the method for obtaining the first angle of the target steering wheel rotation can be that the steering wheel rotation angle information is obtained by a steering wheel rotation angle sensor.

[0063] It can be understood that, in actual application, for different types of vehicles and measurement methods, the method for obtaining the first angle of the target steering wheel rotation can be adjusted accordingly, and the embodiment of the application does not limit this.

[0064] Referring to Figure 4 In an embodiment, the first set values are arranged in a straight line from the second angle to the third angle.

[0065] The first set values arranged in a straight line can avoid the poor driving experience caused by the sudden change of the target steering wheel rotation speed due to the rapid change of the target steering wheel rotation speed.

[0066] Referring to Figure 4As shown, when the first angle of the target steering wheel rotation is less than the second angle, the target steering wheel rotation speed is not limited, when the first angle of the target steering wheel rotation is greater than the second angle and less than the third angle, the target steering wheel rotation speed is the first set value, and the target steering wheel rotation speed decreases as the first angle increases.

[0067] In another embodiment, from the second angle to the third angle, the first set value is arranged in a curve, but the change of the target steering wheel rotation speed needs to meet the driving experience of the driver.

[0068] In an embodiment, the second angle is a rack end protection limit start angle; and / or, the third angle is a soft stop point angle of the vehicle.

[0069] When the second angle is the rack end protection limit start angle, the target steering wheel rotation speed is the first set value only when the first angle is greater than the second angle, that is, the rack end protection method of the electric power steering system does not affect the normal use of the target steering wheel, and prolongs the service life of the electric power steering system 4.

[0070] It can be understood that the rack end protection limit start angle and the soft stop point angle will be different for different models of vehicles, and the rack end protection limit start angle and the soft stop point angle are set according to the use requirements of the vehicle, and the embodiments of the present application do not make specific limitations.

[0071] In an embodiment, the first condition includes that the torque direction of the target steering wheel is the same as the rotation direction of the target steering wheel, the vehicle speed is less than a calibration value, and the rotation angle signal of the target steering wheel is normal.

[0072] In actual application, the calibration value refers to a vehicle speed limit value, which can be adjusted according to different vehicles, and is generally set to a low speed. That is, when the torque direction of the target steering wheel is the same as the rotation direction of the target steering wheel, the vehicle speed is low, and the rotation angle signal of the target steering wheel is normal, the rack end protection limit is used to avoid the influence of the first set value of the target steering wheel rotation speed on driving when the vehicle is at high speed and the rotation angle signal of the target steering wheel is abnormal.

[0073] In an embodiment, the target steering wheel rotation speed is related to the electric steering assist, and in the step of the target steering wheel rotation speed being the first set value when the vehicle is in the first condition; the electric steering assist is adjusted so that the target steering wheel rotation speed is the first set value.

[0074] Referring to Figure 1 As shown, in an embodiment, after the step of obtaining the first angle of the target steering wheel rotation, the method further includes the following steps,

[0075] S12, determining whether the first angle is greater than the third angle;

[0076] S13, when the first angle is greater than the third angle, determining whether the driver intervenes in the steering wheel rotation;

[0077] S14, when the driver does not intervene in the steering wheel rotation, determining whether the vehicle is in a second condition;

[0078] S15, when the vehicle is in the second condition, the target steering wheel is returned to the third angle.

[0079] The rack end protection method of the electric power steering system in the embodiment of the application avoids the rack from stopping at the first angle to cause mechanical wear, so as to prolong the service life of the electric power steering system 4.

[0080] Referring to Figure 2 In an embodiment, the step of determining whether the driver intervenes in the steering wheel rotation includes,

[0081] S21, obtaining a target steering wheel torque T;

[0082] S22, determining whether the target steering wheel torque T is less than T1;

[0083] S23, when the target steering wheel torque T is less than T1, determining whether the target steering wheel torque T is less than T1 for a first time and a descending slope of the target steering wheel torque exceeds A;

[0084] S24, when the target steering wheel torque T is less than T1 for the first time and the descending slope of the target steering wheel torque exceeds A, it is determined that the driver does not intervene in the steering wheel rotation;

[0085] S25, when the target steering wheel torque T is not less than T1, determining whether the target steering wheel torque T is greater than T2, wherein T2 is greater than T1;

[0086] S26, when the target steering wheel torque T is greater than T2, determining whether the target steering wheel torque T is greater than T2 for a second time;

[0087] S27, when the target steering wheel torque T is greater than T2 for the second time, it is determined that the driver intervenes in the steering wheel rotation.

[0088] The determination of the driver's intervention in the steering wheel rotation is mainly based on the steering wheel torque T input by the driver. Among them, T1, T2, the first time, the torque drop slope and the second time are all calibration values, which are set according to the use requirements and vehicle requirements. The sampling period Δt of the determination of the driver's intervention in the steering wheel rotation is also set as a calibration value.

[0089] In an embodiment, the second condition includes that the vehicle speed of the vehicle is less than a calibration value, and the target steering wheel rotation angle signal is normal.

[0090] In actual application, the calibration value refers to the speed limit value, which can be adjusted according to different vehicles, and is generally set to a lower speed. That is, when the vehicle is at low speed, the target steering wheel rotation angle signal is normal, and the driver does not intervene in the steering wheel rotation, the target steering wheel will be turned to the third angle, so as to avoid the influence of the turning of the target steering wheel on the driving when the vehicle is at high speed and the target steering wheel rotation angle signal is abnormal.

[0091] Referring to Figure 1 In an embodiment, after determining whether the driver intervenes in the steering wheel rotation, the step of the first angle being greater than the third angle further includes the following steps:

[0092] S16, when the driver intervenes in the steering wheel rotation, determining whether the vehicle is in a second condition;

[0093] S17, when the vehicle is in the second condition, the target steering wheel rotation speed is a second set value, and the second set value is the minimum value in the first set value.

[0094] When the first angle is greater than the third angle target, and the driver intervenes in the steering wheel rotation, the steering wheel rotation speed is the second set value, which can avoid the rack impacting the limiting device of the electric power steering system 4 at a very high speed, so as to realize the protection of the end of the rack.

[0095] The electric power steering system 4 is a power steering system that directly relies on the motor to provide auxiliary torque. In the rack end protection method of the electric power steering system in the embodiment, the target steering wheel rotation speed and the turning are adjusted by adjusting the electric power steering assistance.

[0096] In an embodiment, the adjustment of the electric power steering assistance is realized by adjusting the motor current. In the step of the target steering wheel rotation speed being the first set value, the target steering wheel rotation speed is the first set value by reducing the motor current.

[0097] It can be understood that the target steering wheel rotation speed is affected by multiple factors, such as the torque received by the target steering wheel, and therefore, in order to make the target steering wheel rotation speed be the first set value, the motor current reduction value will be different. In order to prevent the motor current from being reduced too fast to affect the rack experience, the motor current reduction slope range can be set.

[0098] In an embodiment, in the step of target steering wheel rotation to the third angle, the target steering wheel rotation speed is first increased to the rated rotation speed and then decreased until it stops at the third angle. The setting of the target steering wheel rotation speed can increase the driver's rack experience. The target steering wheel rotation speed is also achieved by adjusting the motor current. When the target steering wheel rotation speed is increased, the motor current is increased; when the target steering wheel rotation speed is the rated rotation speed, the motor current is relatively stable; and when the target steering wheel rotation speed is decreased, the motor current is decreased. The rising current slope and the falling current slope of the motor current are both set values, so as to avoid the motor current rising or falling too fast to cause the steering wheel rotation to suddenly change, affect the driving feeling, and improve the driver's experience. The set values of the rising current slope and the falling current slope need to meet the requirements of different users for the steering wheel rotation speed and the requirements of different vehicle models for the steering wheel rotation speed. In actual application, the motor current should be set with a limit value to prevent the abuse of motor assistance, and the limit value can be set according to the actual use demand.

[0099] In another embodiment, according to the requirement of the target steering wheel rotation speed setting, the motor speed is used as feedback, and the PID algorithm is used to output the motor current required by the target steering wheel rotation.

[0100] Referring to Figure 4 As shown in the figure, the rack end protection method of the electric power steering system in the embodiment of the application is divided into two parts with the third angle as the boundary. In the first part, the first angle of the target steering wheel rotation is greater than the second angle and less than the third angle, which is the rack end protection limit. In the second part, the first angle of the target steering wheel rotation is greater than the third angle, which is the target steering wheel rotation.

[0101] The rack end protection limit determines whether to limit the motor current according to the first angle of the target steering wheel rotation. When the first angle of the target steering wheel rotation is greater than the second angle and less than the third angle, the motor current is reduced according to the limit value control algorithm, so as to reduce the motor assistance and achieve the purpose of protecting the rack end.

[0102] In the target steering wheel rotation, when the first angle of the target steering wheel rotation is greater than the third angle and the vehicle is in the second condition, the target steering wheel is rotated to the third angle at a certain rotation speed by controlling the motor current.

[0103] The rack end protection method of the electric power steering system in the embodiment of the application prolongs the service life of the electric power steering system 4 by lowering the target steering wheel rotation speed and by rotating the target steering wheel back when the target steering wheel is close to the rack end, through the relationship between the first angle and the second angle and the third angle.

[0104] Referring to Figure 3 An embodiment of the application further provides a vehicle, which comprises a steering wheel angle detection module 1, a vehicle state acquisition module 2, an electric power steering system 4 and a steering wheel rotation control module 3, the steering wheel angle detection module 1 is used to acquire the rotation angle of a target steering wheel; the vehicle state acquisition module 2 is used to acquire the state in which the vehicle is, the state in which the vehicle is comprises a first condition; the electric power steering system 4 is used to provide electric power steering assistance for the rotation of the target steering wheel; and the steering wheel rotation control module 3 is used to control the electric power steering assistance of the electric power steering system 4 according to the rotation angle of the target steering wheel and the state in which the vehicle is, so that the target steering wheel rotation speed is a first set value.

[0105] Referring to Figure 3 Figure 3 In an embodiment, the vehicle further comprises a steering wheel torque detection module 5, the steering wheel torque detection module 5 is used to acquire the torque of the target steering wheel, and the state in which the vehicle is further comprises a second condition; and the steering wheel rotation control module 3 is used to control the electric power steering system 4 according to the rotation angle of the target steering wheel, the torque of the target steering wheel and the state in which the vehicle is, so that the target steering wheel is rotated back to a third angle.

[0106] The steering wheel rotation control module 3 in the vehicle can control the target steering wheel rotation speed and the target steering wheel rotation back according to the rotation angle of the target steering wheel, the state in which the vehicle is, the electric power steering system 4 and the steering wheel torque detection module 5, so that the electric power steering system 4 of the vehicle has the advantage of long service life.

[0107] The above merely describes the preferred embodiments of the application, but the application is not limited to the above embodiments, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A method for protecting the rack end of an electric power steering system, characterized in that, Includes the following steps, Obtain the first angle of rotation of the target steering wheel; Determine whether the first angle is greater than the second angle and less than the third angle; When the first angle is greater than the second angle and less than the third angle, determine whether the vehicle is under the first condition; When the vehicle is under the first condition, the target steering wheel rotation speed is a first set value; The first set value decreases as the first angle increases; After obtaining the first angle of rotation of the target steering wheel as described in step [1], the following steps are also included: Determine whether the first angle is greater than the third angle; When the first angle is greater than the third angle, determine whether the driver intervenes in turning the steering wheel; If the driver does not intervene in turning the steering wheel, determine whether the vehicle is in the second condition; The vehicle is in the second condition, and the target steering wheel is turned to the third angle.

2. The method for protecting the rack end of an electric power steering system according to claim 1, characterized in that, From the second angle to the third angle, several of the first set values ​​are set in a straight line.

3. The method for protecting the rack end of an electric power steering system according to claim 1, characterized in that, The second angle is the starting angle for rack end protection and restriction; and / or, The third angle is the soft stop angle of the vehicle.

4. The method for protecting the rack end of an electric power steering system according to claim 1, characterized in that, The first condition includes that the torque direction of the target steering wheel is the same as the angular direction of the target steering wheel, the vehicle speed is less than the calibrated value, and the angular signal of the target steering wheel is normal.

5. The method for protecting the rack end of an electric power steering system according to claim 1, characterized in that, The target steering wheel rotation speed is related to the electric power steering, and in the step where the vehicle is under the first condition, the target steering wheel rotation speed is a first set value. By adjusting the electric power steering, the target steering wheel rotation speed is made to a first set value.

6. The method for protecting the rack end of an electric power steering system according to claim 1, characterized in that, The steps for determining whether the driver has intervened in turning the steering wheel include: Obtain the target steering wheel torque T; Determine whether the target steering wheel torque T is less than T1; When the target steering wheel torque T is less than T1, determine whether the target steering wheel torque T is less than T1 for a continuous period of time, and whether the slope of the target steering wheel torque decrease exceeds A; If the target steering wheel torque T is less than T1 for a continuous period of time, and the slope of the decrease in the target steering wheel torque exceeds A, it is determined that the driver has not intervened in steering wheel rotation. When the target steering wheel torque T is not less than T1, determine whether the target steering wheel torque T is greater than T2, where T2 is greater than T1; If the target steering wheel torque T is greater than T2, then determine whether the target steering wheel torque T being greater than T2 continues for a second time period. If the target steering wheel torque T is greater than T2 for a second period of time, it is determined that the driver intervenes in steering wheel rotation.

7. The method for protecting the rack end of an electric power steering system according to claim 1, characterized in that, The second condition includes that the vehicle speed is less than the calibrated value and that the steering wheel angle signal of the target is normal.

8. The method for protecting the rack end of an electric power steering system according to claim 1, characterized in that, After determining whether the driver has intervened in steering wheel rotation following the step where the first angle is greater than the third angle, the following steps are also included. When the driver intervenes by turning the steering wheel, determine whether the vehicle is in the second condition; The vehicle is under a second condition, and the target steering wheel rotation speed is a second set value, which is the minimum of the first set values.

9. A vehicle, characterized in that, include, Steering wheel angle detection module (1) is used to obtain the rotation angle of the target steering wheel; Vehicle status acquisition module (2) is used to acquire the status of the vehicle, wherein the status of the vehicle includes a first condition; Electric power steering system (4) is used to provide electric power steering assistance for the rotation of the target steering wheel; Steering wheel rotation control module (3) is used to control the electric power steering system (4) according to the rotation angle of the target steering wheel and the state of the vehicle, so that the rotation speed of the target steering wheel is a first set value; The vehicle also includes: a steering wheel torque detection module (5), which is used to obtain the torque of the target steering wheel, and the state of the vehicle also includes a second condition; The steering wheel rotation control module (3) is used to control the electric power steering system (4) according to the rotation angle of the target steering wheel, the torque of the target steering wheel and the state of the vehicle, so that the target steering wheel rotates back to the third angle.

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