Wheel alignment abnormality detection device

Abstract

To provide a wheel alignment abnormality detection device that can quickly detect alignment abnormality of wheels.SOLUTION: A wheel alignment abnormality detection device is provided in a vehicle that has: a vehicle speed sensor detecting a vehicle speed; a plurality of vehicle speed sensors detecting a speed of a plurality of wheels respectively; and a steering angle sensor detecting a steering angle of steering. When a first condition that all of a difference between each speed detected respectively by the plurality of vehicle wheel speed sensors and the vehicle speed detected by the wheel speed sensor are smaller than a first threshold TH1 is established (S2), and a second condition that the steering angle detected by the steering angle sensor is smaller than a second threshold TH2 is not established (S3), the wheel alignment abnormality detection device is configured to detect presence of alignment abnormality (S6).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a wheel alignment abnormality detection device.

Background Art

[0002] Conventionally, based on the difference between the number of rotations of a wheel while a vehicle travels a predetermined distance and a threshold value which is the number of rotations of the wheel while the vehicle travels a predetermined distance when the wheel alignment is normal, a technique for detecting a misalignment of the wheel has been proposed in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the conventional technique as described above cannot detect a misalignment of the wheel unless the vehicle travels a predetermined distance, and thus there is a problem that a misalignment of the wheel (hereinafter referred to as "alignment abnormality") cannot be detected promptly.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a wheel alignment abnormality detection device capable of promptly detecting a wheel alignment abnormality.

Means for Solving the Problems

[0006] The wheel alignment abnormality detection device according to the present invention is provided in a vehicle having a vehicle speed sensor for detecting the vehicle speed, a plurality of wheel speed sensors for respectively detecting the speeds of a plurality of wheels, and a steering angle sensor for detecting the steering angle of the steering. When a first condition that all differences between the respective speeds detected by the plurality of wheel speed sensors and the vehicle speed detected by the vehicle speed sensor are smaller than a first threshold value is satisfied, and a second condition that the steering angle detected by the steering angle sensor is smaller than a second threshold value is not satisfied, it is configured to detect that there is an alignment abnormality in the plurality of wheels.

Effects of the Invention

[0007] The present invention can provide a wheel alignment abnormality detection device capable of quickly detecting an alignment abnormality of wheels.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0009] The wheel alignment abnormality detection device according to an embodiment of the present invention is provided in a vehicle having a vehicle speed sensor that detects the vehicle speed, a plurality of wheel speed sensors that respectively detect the speeds of a plurality of wheels, and a steering angle sensor that detects the steering angle of the steering. When a first condition that all differences between the respective speeds detected by the plurality of wheel speed sensors and the vehicle speed detected by the vehicle speed sensor are smaller than a first threshold is satisfied, and a second condition that the steering angle detected by the steering angle sensor is smaller than a second threshold is not satisfied, it is detected that there is an alignment abnormality in the plurality of wheels. Thereby, the wheel alignment abnormality detection device according to an embodiment of the present invention can promptly detect an alignment abnormality of the wheels.

Example

[0010] Hereinafter, a vehicle to which a wheel alignment abnormality detection device according to an embodiment of the present invention is applied will be described with reference to the drawings.

[0011] As shown in FIG. 1, the vehicle 1 includes wheels 2a to 2d, wheel speed sensors 3a to 3d, a steering 4, a steering angle sensor 5, a vehicle speed sensor 6, a yaw rate sensor 7, an alarm device 8, and an ECU (Electronic Control Unit) 9. In FIG. 1, four wheels 2a to 2d and four wheel speed sensors 3a to 3d are shown, but the number of wheels and wheel speed sensors of the vehicle 1 is not limited.

[0012] The wheel speed sensors 3a to 3d respectively detect the speeds of the wheels 2a to 2d. The steering angle sensor 5 detects the steering angle of the steering 4. The vehicle speed sensor 6 detects the vehicle speed of the vehicle 1. The yaw rate sensor 7 detects the yaw rate of the vehicle 1.

[0013] In this embodiment, the alarm device 8 is constituted by a lamp provided on the instrument panel of the vehicle 1. Note that the alarm device 8 may be constituted by a display device, may be constituted by a speaker, or may be constituted by a combination of at least two of a lamp, a display device, and a speaker.

[0014] The ECU 9 is composed of a computer unit including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory for storing backup data and the like, an input port, and an output port.

[0015] In the ROM of this computer unit, a program for causing the computer unit to function as the ECU 9 is stored together with various constants and various maps. That is, by the CPU executing the program stored in the ROM using the RAM as a work area, this computer unit functions as the ECU 9 in the present embodiment.

[0016] Various sensors including wheel speed sensors 3a to 3d, a steering angle sensor 5, a vehicle speed sensor 6, and a yaw axis angular velocity sensor 7 are connected to the input port of the ECU 9. Various control targets including an alarm device 8 are connected to the output port of the ECU 9. The ECU 9 controls various control targets connected to the output port based on information obtained from various sensors connected to the input port.

[0017] In the present embodiment, the ECU 9 constitutes a wheel alignment abnormality detection device. The ECU 9 detects that there is an alignment abnormality (hereinafter also simply referred to as "alignment abnormality") of the wheels 2a to 2d when a first condition that the differences between the respective speeds (hereinafter also simply referred to as "wheel speeds") detected by the wheel speed sensors 3a to 3d and the vehicle speed (hereinafter also simply referred to as "actual vehicle speed") detected by the vehicle speed sensor 6 are all smaller than a first threshold value TH1 is satisfied, and a second condition that the steering angle detected by the steering angle sensor 5 is smaller than a second threshold value TH2 is not satisfied.

[0018] The first threshold value TH1 is set as the lower limit value at which it is determined that the vehicle 1 is not traveling straight. Therefore, if the first condition is satisfied, it is determined that the vehicle 1 is traveling straight, and if the first condition is not satisfied, it is determined that the vehicle 1 is performing a turning operation. The first threshold value TH1 is set so as to decrease as the vehicle speed increases according to the first map stored in the ROM of the ECU 9.

[0019] Note that the first map may be individually stored in the ROM of the ECU 9 for each of the wheel speed sensors 3a to 3d. For example, a first map for the steering wheel for the wheel speed sensor that detects the speed of the steering wheel among the wheels 2a to 2d and a first map for the non-steering wheels for the wheel speed sensor that detects the speed of the wheels other than the steering wheel among the wheels 2a to 2d may be stored in the ROM of the ECU 9.

[0020] Also, a first map for the driving wheels for the wheel speed sensor that detects the speed of the driving wheels among the wheels 2a to 2d and a first map for the driven wheels for the wheel speed sensor that detects the speed of the driven wheels among the wheels 2a to 2d may be stored in the ROM of the ECU 9.

[0021] The second threshold value TH2 is set as the lower limit value at which it is determined that the steering 4 is being operated to turn the vehicle 1. Therefore, if the second condition is satisfied, it is determined that the steering 4 is not being operated to turn the vehicle 1, and if the second condition is not satisfied, it is determined that the steering 4 is being operated to turn the vehicle 1. The second threshold value TH2 is set so as to decrease as the vehicle speed increases according to the second map stored in the ROM of the ECU 9.

[0022] When the first condition is satisfied and the second condition is not satisfied, although it is determined that the vehicle 1 is traveling straight, it is determined that the steering 4 is being operated to turn the vehicle 1. Therefore, the ECU 9 detects that there is an alignment abnormality.

[0023] Also, when the first condition is not satisfied and the second condition is satisfied, although the vehicle 1 is turning, it is determined that the steering 4 is not being operated to turn the vehicle 1. Therefore, the ECU 9 detects that there is an alignment abnormality.

[0024] Further, when the first condition is not satisfied, the second condition is not satisfied, and a third condition that the yaw-axis angular velocity detected by the yaw-axis angular velocity sensor 7 is smaller than a third threshold value TH3 is satisfied, the ECU 9 detects that there is an alignment abnormality.

[0025] The third threshold value TH3 is determined as a lower limit value at which it is determined that the attitude of the vehicle 1 is changing in the yaw angle direction. Therefore, if the third condition is satisfied, it is determined that the attitude of the vehicle 1 is not changing in the yaw angle direction, and if the third condition is not satisfied, it is determined that the attitude of the vehicle 1 is changing in the yaw angle direction. The third threshold value TH3 is determined to increase as the vehicle speed increases and to increase as the steering angle increases according to a third map stored in the ROM of the ECU 9.

[0026] When the first condition is not satisfied, the second condition is not satisfied, and the third condition is satisfied, the steering 4 is operated to turn the vehicle 1. Although the vehicle 1 is turning, it is determined that the attitude of the vehicle 1 is not changing in the yaw angle direction. Therefore, the ECU 9 detects that there is an alignment abnormality.

[0027] When the number of times the ECU 9 detects an alignment abnormality (hereinafter, also simply referred to as "abnormality detection count") exceeds a predetermined number n, at the start of the next driving cycle, the warning device 8 is caused to issue a warning in a first mode. The predetermined number n may be 0 or more, and in this embodiment, it is 16.

[0028] In this embodiment, when the ECU 9 causes the warning device 8 to issue a warning in the first mode, the lamp (hereinafter, simply referred to as "warning lamp") constituting the warning device 8 is turned on for a certain period of time (for example, 10 seconds).

[0029] When the number of times the warning device 8 has issued a warning exceeds a certain number N (for example, 40 times), or when the vehicle 1 has traveled more than a certain distance L (for example, 500 km) after the warning device 8 has issued a warning, the ECU 9 causes the warning device 8 to issue a warning in a second mode.

[0030] The certain number N and the certain distance L are determined to be values at which it is estimated that the uneven wear amount of the tires constituting the wheels 2a to 2d exceeds the allowable amount. In this embodiment, when the ECU 9 causes the warning device 8 to issue a warning in the second mode, the warning lamp is constantly lit.

[0031] Note that since the warning in the second mode is intended to prompt adjustment of the alignment of the wheels 2a to 2d at a repair factory or the like, the warning device 8 may be configured to include a display device or a speaker, and output a message prompting adjustment of the alignment of the wheels 2a to 2d at a repair factory or the like via the display device or the speaker.

[0032] The alignment abnormality detection operation of the ECU 9 configured as described above will be described with reference to FIG. 2. Note that the alignment abnormality detection operation described below is repeatedly executed while the ECU 9 is operating.

[0033] First, in S1, the ECU 9 determines whether the vehicle speed detected by the vehicle speed sensor 6 is higher than a predetermined speed THv. The predetermined speed THv is set to a vehicle speed at which it is estimated that the vehicle 1 is traveling stably, and in this embodiment, it is 60 km / h.

[0034] If it is determined in S1 that the vehicle speed detected by the vehicle speed sensor 6 is higher than the predetermined speed THv, the ECU 9 executes the process of S2. If it is determined in S1 that the vehicle speed detected by the vehicle speed sensor 6 is not higher than the predetermined speed THv, the ECU 9 ends the alignment abnormality detection operation.

[0035] In S2, the ECU 9 determines whether the differences between each wheel speed and the actual vehicle speed are all smaller than the first threshold value TH1. That is, in S2, the ECU 9 determines whether the first condition is satisfied. If it is determined that the first condition is satisfied, the ECU 9 executes the process of S3. If it is determined that the first condition is not satisfied, the ECU 9 executes the process of S4.

[0036] In S3, the ECU 9 determines whether the steering angle detected by the steering angle sensor 5 is smaller than the second threshold value TH2. That is, in S3, the ECU 9 determines whether the second condition is satisfied. If it is determined that the second condition is satisfied, the ECU 9 ends the alignment abnormality detection operation. If it is determined that the second condition is not satisfied, the ECU 9 executes the process of S6.

[0037] In S4, the ECU 9 determines whether the steering angle detected by the steering angle sensor 5 is smaller than the second threshold value TH2. That is, in S4, the ECU 9 determines whether the second condition is satisfied. If it is determined that the second condition is satisfied, the ECU 9 executes the process of S6. If it is determined that the second condition is not satisfied, the ECU 9 executes the process of S5.

[0038] In S5, the ECU 9 determines whether the yaw-axis angular velocity detected by the yaw-axis angular velocity sensor 7 is smaller than the third threshold value TH3. That is, in S5, the ECU 9 determines whether the third condition is satisfied. If it is determined that the third condition is satisfied, the ECU 9 executes the process of S6. If it is determined that the third condition is not satisfied, the ECU 9 ends the alignment abnormality detection operation.

[0039] In S6, the ECU 9 executes the process at the time of alignment abnormality detection. In the process at the time of alignment abnormality detection, the ECU 9 adds 1 to the number of abnormality detections. After executing the process of S6, the ECU 9 ends the alignment abnormality detection operation.

[0040] The warning operation of the ECU 9 will be described below with reference to FIG. 3. The warning operation described below is repeatedly executed while the ECU 9 is operating.

[0041] First, in S11, the ECU 9 determines whether it is the start of a driving cycle. If it is determined in S11 that it is the start of a driving cycle, the ECU 9 executes the process of S12. If it is determined in S11 that it is not the start of a driving cycle, the ECU 9 executes the process of S21.

[0042] In S12, the ECU 9 determines whether the number of abnormality detections has exceeded a predetermined number n. If it is determined in S12 that the number of abnormality detections has exceeded the predetermined number n, the ECU 9 executes the process of S13. If it is determined in S12 that the number of abnormality detections has not exceeded the predetermined number n, the ECU 9 executes the process of S16.

[0043] In S13, the ECU 9 turns on the warning lamp for a certain period of time. After executing the process of S13, the ECU 9 executes the process of S14. In S14, the ECU 9 adds 1 to the number of warnings. The number of warnings represents the number of driving cycles in which the process of turning on the warning lamp for a certain period of time has been continuously performed. After executing the process of S14, the ECU 9 executes the process of S15.

[0044] In S15, the ECU 9 sets the warning flag to on. The warning flag set to on indicates that the warning lamp has been turned on for a certain period of time at the start of the driving cycle. Conversely, the warning flag set to off indicates that the warning lamp has not been turned on for a certain period of time at the start of the driving cycle. After executing the process of S15, the ECU 9 executes the process of S18.

[0045] In S16, the ECU 9 resets the warning count to 0. After executing the process of S16, the ECU 9 executes the process of S17. In S17, the ECU 9 sets the warning flag to off. After executing the process of S17, the ECU 9 executes the process of S18.

[0046] In S18, the ECU 9 resets the abnormality detection count to 0. After executing the process of S18, the ECU 9 executes the process of S19. In S19, the ECU 9 determines whether the warning count exceeds a certain number N.

[0047] In S19, if it is determined that the warning count exceeds the certain number N, the ECU 9 executes the process of S20. In S19, if it is determined that the warning count does not exceed the certain number N, the ECU 9 ends the warning operation. In S20, the ECU 9 turns on the warning lamp constantly. After executing the process of S20, the ECU 9 ends the warning operation.

[0048] In S21, the ECU 9 determines whether the warning flag is on. In S21, if it is determined that the warning flag is on, the ECU 9 executes the process of S22. In S21, if it is determined that the warning flag is not on, the ECU 9 ends the warning operation.

[0049] In S22, the ECU 9 determines whether the driving distance from the start of the driving cycle exceeds a certain distance L based on the vehicle speed detected by the vehicle speed sensor 6 and the like. In S22, if it is determined that the driving distance exceeds the certain distance L, the ECU 9 executes the process of S20. In S22, if it is determined that the driving distance does not exceed the certain distance L, the ECU 9 ends the warning operation.

[0050] In the above-mentioned S20 of the warning operation, when the ECU9 continuously lights the warning lamp as the warning in the second mode, it maintains the lighting state of the warning lamp until an information reset command is input. The information reset command is input to the ECU9 after the alignment of the wheels 2a to 2d has been adjusted during operation at a maintenance factory or the like.

[0051] Therefore, during the period from when the warning lamp is continuously lit until an information reset command is input, the ECU9 prohibits the execution of the alignment abnormality detection operation and the warning operation.

[0052] When an information reset command is input, the ECU9 initializes various variables such as the warning count and the warning flag, and starts the execution of the alignment abnormality detection operation and the warning operation.

[0053] As described above, when the first condition is satisfied and the second condition is not satisfied, the wheel alignment abnormality detection device according to the present embodiment detects that there is an alignment abnormality in the wheels 2a to 2d, so that the alignment abnormality in the wheels 2a to 2d can be quickly detected.

[0054] In addition, when the first condition is not satisfied and the second condition is satisfied, the wheel alignment abnormality detection device according to the present embodiment detects that there is an alignment abnormality in the wheels 2a to 2d, so that the alignment abnormality in the wheels 2a to 2d can be quickly detected.

[0055] In addition, when the first condition is not satisfied, the second condition is not satisfied, and the third condition is satisfied, the wheel alignment abnormality detection device according to the present embodiment detects that there is an alignment abnormality in the wheels 2a to 2d, so that the alignment abnormality in the wheels 2a to 2d can be quickly detected.

[0056] In addition, when the number of times the wheel alignment abnormality detection device according to this embodiment detects that there is an alignment abnormality in wheels 2a to 2d exceeds a predetermined number of times n, an alarm is issued to the alarm device 8 at the start of the next driving cycle, so that the driver can recognize the alignment abnormality in wheels 2a to 2d.

[0057] In particular, an alignment abnormality in wheels 2a to 2d has an adverse effect on the driver's psychology, such as impairing the straight-ahead performance of the vehicle 1 or making it difficult for the driver to feel that the vehicle 1 turns even when the steering wheel 4 is operated.

[0058] Since the wheel alignment abnormality detection device according to this embodiment can cause the driver to recognize the alignment abnormality in wheels 2a to 2d, the driver can drive the vehicle 1 safely and with peace of mind.

[0059] In addition, when the number of times the alarm device 8 issues an alarm exceeds a certain number of times N, or when the vehicle 1 travels beyond a certain distance after the alarm device 8 issues an alarm, the wheel alignment abnormality detection device according to this embodiment causes the alarm device 8 to issue an alarm in another manner, so that the intensity of the alarm can be increased to prompt adjustment of the alignment of wheels 2a to 2d.

[0060] In addition, since the wheel alignment abnormality detection device according to this embodiment can quickly detect an alignment abnormality in wheels 2a to 2d, it is possible to suppress an increase in the environmental load due to an increase in the rolling resistance of the tires, deterioration of fuel consumption, and increase in exhaust gas.

[0061] In this embodiment, an example in which the warning lamp is constantly lit as the warning in the second mode is described, in which the lighting state of the warning lamp is maintained until an information reset command is input, and the execution of the alignment abnormality detection operation and the warning operation is prohibited.

[0062] On the other hand, even if the warning lamp is constantly lit as the warning in the second aspect, the wheel alignment abnormality detection operation and the warning operation are continued, and when the number of times of detecting an alignment abnormality of the wheels 2a to 2d in one driving cycle does not exceed a predetermined number n, it may be determined that the alignment of the wheels 2a to 2d has been adjusted, and the warning lamp may be turned off.

[0063] Further, even if the warning lamp is constantly lit as the warning in the second aspect, the wheel alignment abnormality detection device according to the present embodiment continues to execute the alignment abnormality detection operation and the warning operation, and when driving cycles in which the number of times of detecting an alignment abnormality of the wheels 2a to 2d does not exceed a predetermined number n continue for a plurality of times (for example, a certain number N), it may be determined that the alignment of the wheels 2a to 2d has been adjusted, and the warning lamp may be turned off.

[0064] As described above, the embodiments of the present invention have been disclosed, but it is obvious that changes can be made to the present embodiment without departing from the scope of the present invention. The embodiments of the present invention are disclosed on the premise that equivalents to which such changes are made are included in the invention described in the claims.

Explanation of Reference Numerals

[0065] 1 Vehicle 2a~2d Wheels 3a~3d Wheel speed sensors 4 Steering 5 Steering angle sensor 6 Vehicle speed sensor 7 Yaw axis angular velocity sensor 8 Warning device 9 ECU (Wheel alignment abnormality detection device)

Claims

1. A vehicle speed sensor for detecting vehicle speed, a plurality of wheel speed sensors for respectively detecting the speeds of a plurality of wheels, and a steering angle sensor for detecting the steering angle of the steering, provided in a vehicle, when a first condition that all differences between the respective speeds detected by the plurality of wheel speed sensors and the vehicle speed detected by the vehicle speed sensor are smaller than a first threshold is satisfied, and when a second condition that the steering angle detected by the steering angle sensor is smaller than a second threshold is not satisfied, a wheel alignment abnormality detection device characterized by detecting that there is an alignment abnormality in the plurality of wheels.

2. when the first condition is not satisfied and the second condition is satisfied, the wheel alignment abnormality detection device according to claim 1, characterized by detecting that there is an alignment abnormality in the plurality of wheels.

3. the vehicle further includes a yaw axis angular velocity sensor for detecting the yaw axis angular velocity of the vehicle, when the first condition is not satisfied, the second condition is not satisfied, and when a third condition that the yaw axis angular velocity detected by the yaw axis angular velocity sensor is smaller than a third threshold is satisfied, the wheel alignment abnormality detection device according to claim 2, characterized by detecting that there is an alignment abnormality in the plurality of wheels.

4. the vehicle further includes an alarm device for issuing an alarm, when the number of times of detecting that there is an alignment abnormality in the plurality of wheels exceeds a predetermined number of times, causing the alarm device to issue an alarm at the start of the next driving cycle. The wheel alignment abnormality detection device according to any one of claims 1 to 3.

5. when the number of times of causing the alarm device to issue an alarm exceeds a certain number of times, or when the vehicle has traveled beyond a certain distance after causing the alarm device to issue an alarm, the wheel alignment abnormality detection device according to claim 4, characterized by causing the alarm device to issue an alarm in another manner.

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