JP2001114089A - Failure detecting method for car speed sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a failure detecting device for a car speed sensor having high reliability and a facilitated process for detecting failure. SOLUTION: A control unit 12 performs the effective sensor detecting process for detecting the existence of car speed sensors 3, 4, 5, 6 outputting the speed more than the first reference value or more among plural wheel speed sensors 3, 4, 5, 6 and the car speed discriminating process for discriminating the output from a car speed sensor 8. In the case where at least one of the wheel speed sensors 3, 4, 5, 6 detecting the first reference value or more of speed in the effective sensor detection exists and where the output from the car speed sensor 8 is not detected in the car speed discriminating process, the car speed sensor 8 is determined to be in failure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vehicle equipped with a wheel speed sensor for detecting the rotational speed of a wheel for each wheel and having a vehicle speed sensor for detecting the moving speed of the vehicle. The present invention relates to a method for detecting a sensor failure, and more particularly, to an improvement for enabling highly reliable failure detection to be realized at low cost.

[0002]

2. Description of the Related Art In recent vehicles, brake functions have been made more intelligent in order to improve the drivability of the vehicle, reduce the burden on the driver, and the like, and antilock brake systems and braking force holding systems have been developed. Vehicles equipped with a brake system equipped with both are increasing. The anti-lock brake system monitors the speed of each wheel by the output of a wheel speed sensor equipped for each wheel of the vehicle,
By controlling the braking force of each wheel during braking so that the wheels do not lock during traveling, slippage due to locking of the wheels during braking is prevented, driving stability is improved, braking distance is shortened, and the like. . The braking force retention system is usually
The stop state of the vehicle is determined from the output of the vehicle speed sensor that detects the moving speed of the vehicle body, and when the vehicle stops, the braking force that was applied at that time is maintained, so that the vehicle can be stopped temporarily by a stop signal or when starting up a hill. This reduces the burden on the driver. As the vehicle body speed sensor, for example, a vehicle speed sensor for a speedometer that detects an average speed of a drive shaft of the vehicle, a ground sensor that detects a relative displacement speed between a road surface and the vehicle body, and the like are used.

[0003] However, in such a system in which the braking function is multi-functional and each of the braking functions is controlled based on the output of various sensors, when some of the sensors fail, the braking function using the sensors is not used. There is a risk of malfunction. For example, if the vehicle speed sensor fails during running of the vehicle and the output of the vehicle speed sensor disappears, the above-described braking force holding system erroneously determines that the vehicle has stopped, and the vehicle does not actually stop. In addition, there is a risk that the braking force holding operation may be performed. Therefore, in order to prevent such a malfunction of the braking force holding system, it is necessary to monitor the operation of the vehicle speed sensor and to stop the operation of the braking force holding system when the vehicle speed sensor fails. Conventionally, in order to realize such a response, the following failure detection method of the vehicle body speed sensor has been proposed.

[0004] One is proposed for a manual transmission vehicle. An output signal of a clutch stroke sensor for detecting the amount of depression of a clutch pedal and an output of a neutral switch for detecting that the gear position of the transmission is neutral. A signal and an L terminal signal of the alternator which detects that the engine is operating are monitored. Based on these monitoring signals, the transmission is in a gear position other than neutral, the clutch is in the engaged state, and the engine is operating. In this case, it is determined that the vehicle is running, and in this case, if there is no output from the vehicle speed sensor, it is determined that the vehicle speed sensor has failed.

Another one is proposed for an automatic transmission vehicle, and an accelerator stroke sensor for detecting an amount of depression of an accelerator pedal (or an accelerator switch for detecting depression and release of an accelerator pedal). , An output signal of an N-range switch for detecting that the gear position of the transmission is in a neutral range, an output signal of a P-range switch for detecting that the gear position is in a P range (parking position), and an engine. An L terminal signal of the alternator for detecting that the engine is in operation is monitored, and based on these monitored signals, the accelerator pedal is at the depressed position, the gear position is outside the N range or the P range, and the engine is If the vehicle is running, it is determined that the vehicle is running. When there is no is to determine the failure of the vehicle speed sensor.

[0006]

However, any of the above-described conventional methods for detecting a failure of a vehicle speed sensor monitor various output signals from various sensors and switches to determine whether or not the vehicle is traveling. Since these various signals must be processed, the process for detecting the failure of the vehicle speed sensor is complicated, and there is a problem in that the cost of implementing the device is high. Another problem is that a different failure detection method must be selected for an automatic transmission vehicle and a manual transmission vehicle.
Furthermore, any of the failure detection methods is based on the premise that all of the various sensors and switches used to determine whether or not the vehicle is traveling are operating normally. If the vehicle is abnormally operated due to a failure or the like, failure detection of the vehicle body speed sensor becomes impossible. In other words, since the failure detection of the vehicle speed sensor is performed based on the output signals of various sensors and switches, the reliability of the failure detection of the vehicle speed sensor tends to decrease due to the failure of some of the sensors and switches. There was a problem.

The present invention has been made in view of the above circumstances, and since the number of output signals to be monitored is small, a process for detecting a failure of a vehicle body speed sensor is simplified, and at the same time, the process is common to an automatic transmission vehicle and a manual transmission vehicle. It is also possible to reduce the cost of realizing the device, and the number of sensors used for failure detection can be reduced. It is an object of the present invention to provide a method of detecting a failure of a vehicle body speed sensor, which can prevent a decrease in reliability and improve operation reliability, and can therefore realize highly reliable failure detection at low cost.

[0008]

According to the present invention, there is provided a method of detecting a failure of a vehicle speed sensor according to the present invention, wherein a wheel speed sensor for detecting a rotational speed of a wheel is provided for each wheel. A method of detecting a failure of a vehicle speed sensor in a vehicle including a vehicle speed sensor for detecting a moving speed of a vehicle, the method comprising: determining whether there is a wheel speed sensor that outputs a speed equal to or higher than a reference value among a plurality of wheel speed sensors. Effective vehicle detection processing, and vehicle speed determination processing for determining the presence or absence of the output of the vehicle body speed sensor, and at least one wheel speed sensor outputting a speed equal to or higher than the reference value in the validity sensor detection processing. If the vehicle speed sensor is present and it is determined in the vehicle speed determination process that there is no output from the vehicle speed sensor, the vehicle speed sensor is determined to be faulty.

According to the above configuration, the output signals of the vehicle speed sensor and the plurality of wheel speed sensors mounted on the vehicle are monitored, and when these output signals meet predetermined conditions, Is judged to be a failure, and compared to the conventional one that monitors the operating state of the clutch and the transmission, the output signal to be monitored is smaller,
Signal processing for detecting a failure of the vehicle speed sensor is simplified. Further, since the operation state of the transmission is not monitored, the transmission can be used commonly for an automatic transmission vehicle and a manual transmission vehicle. Therefore, it is possible to reduce the cost of realizing the device. Also, as compared with the conventional one that monitors the operating state of the clutch and the transmission, the number of types of sensors and the like used for failure detection can be reduced, so that the decrease in reliability due to the failure of the sensors and the like used for failure detection is reduced. Thus, the operation reliability can be improved, and highly reliable failure detection can be realized at low cost.

According to another aspect of the present invention, there is provided a method for detecting a failure of a vehicle body speed sensor, the method comprising the steps of: In a method for detecting a failure of the vehicle body speed sensor in a vehicle having a vehicle body speed sensor to be detected, a first reference value as a wheel speed reference value;
A first effective sensor detection process is performed in which a second reference value smaller than the first reference value is set, and a presence or absence of a wheel speed sensor detecting a speed equal to or higher than the first reference value is performed. If no wheel speed sensor outputs a speed equal to or higher than the first reference value in the first valid sensor detection process, a speed equal to or higher than the second reference value is output for each wheel axle. A shaft unit effective sensor detecting process for determining the presence or absence of a wheel speed sensor performing the vehicle speed determination process for determining the presence or absence of an output of the vehicle body speed sensor. When there is at least one wheel speed sensor that outputs a speed equal to or higher than a reference value for each wheel axle, and when it is determined in the vehicle speed determination process that there is no output from the vehicle speed sensor, the vehicle speed Special attention is given to determining that the sensor is faulty. To.

Also in the case of the above configuration, the output signals of the vehicle speed sensor and the plurality of wheel speed sensors mounted on the vehicle are monitored, and when these output signals meet predetermined conditions, Is judged to be a failure, and compared to the conventional one that monitors the operating state of the clutch and the transmission, the output signal to be monitored is smaller,
Signal processing for detecting a failure of the vehicle speed sensor is simplified. Further, since the operation state of the transmission is not monitored, the transmission can be used commonly for an automatic transmission vehicle and a manual transmission vehicle. Therefore, it is possible to reduce the cost of realizing the device. Also, as compared with the conventional one that monitors the operating state of the clutch and the transmission, the number of types of sensors and the like used for failure detection can be reduced, so that the decrease in reliability due to the failure of the sensors and the like used for failure detection is reduced. Thus, the operation reliability can be improved, and highly reliable failure detection can be realized at low cost. Further, in the case of the above configuration,
Two reference values, a first reference value and a second reference value, are set as speed values used for failure determination criteria, and failure diagnosis is performed using a second reference value smaller than the first reference value. To do
For example, even during maintenance work such as tire replacement or when traveling at extremely low speed, highly reliable failure detection can be performed on the vehicle body speed sensor.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a method for detecting a failure of a vehicle body speed sensor according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an embodiment of a sensor failure detection device for realizing a method of detecting a failure of a vehicle speed sensor according to the present invention. FIG. 2 is a diagram of a vehicle failure speed sensor implemented by the sensor failure detection device shown in FIG. It is a flowchart which shows the processing procedure of a failure detection method.

The sensor failure detecting device 1 shown in FIG. 1 is provided for each wheel of a vehicle and includes four wheel speed sensors 3, 4, 5, 6 (specifically, for detecting the rotational speed of each wheel). A vehicle speed meter for detecting the drive shaft speed), a vehicle speed sensor 8 for detecting the moving speed of the vehicle body, a display means 10 for displaying a failure of the vehicle speed sensor 8, a wheel speed sensor 3, 4, 5,
6 to monitor the output signals of these sensors 3, 4, 5, 6
And a control unit 12 that determines the failure of the vehicle speed sensor 8 on the basis of the output signal and activates the display means 10 based on the determination result.

Of the four wheel speed sensors 3, 4, 5, 6, the wheel speed sensor 3 is the left front wheel of the vehicle, the wheel speed sensor 4 is the right front wheel of the vehicle, the wheel speed sensor 5 is the left rear wheel of the vehicle,
The wheel speed sensor 6 is mounted on the right rear wheel of the vehicle. 4
The wheel speed sensors 3, 4, 5, and 6 are provided to monitor the speed of each wheel in an anti-lock brake system that controls the braking force of each wheel during braking so that the wheels do not lock during traveling. It is a thing.

In the case of this embodiment, the vehicle speed sensor 8
It is a vehicle speed sensor for a speedometer that detects an average speed of a drive shaft of a vehicle. The vehicle speed sensor 8 is also used to determine the stop of the vehicle in a braking force holding system that holds the braking force applied at the time of a temporary stop due to, for example, a stop signal. The display means 10 is a buzzer that sounds based on a control signal from the control unit 12 or a blinking lamp.

In the control unit 12, a first reference value (speed A) and a second reference value (speed B) smaller than the first reference value are set as reference values of the wheel speed. By comparing the output signals of the wheel speed sensors 3, 4, 5, 6 and the vehicle speed sensor 8 with these reference values, the failure of the vehicle speed sensor 8 is determined. The speed A, which is the first reference value, is a speed that cannot be reached even when the tire is manually rotated, for example, at the time of tire replacement.
It is set to an appropriate value of m or more. The speed B, which is the second reference value, is set in a range equal to or lower than the speed A, which is the first reference value, and is a lower detection limit of the wheel speed sensor.
m.

The specific processing procedure of the control unit 12 is as shown in FIG. First, the first step S201
Then, an effective sensor detection process for determining whether or not any of the four wheel speed sensors 3, 4, 5, 6 outputs a speed equal to or higher than the first reference value is performed. When it is determined in step S201 that there is at least one wheel speed sensor that detects a speed equal to or higher than the first reference value, the process proceeds to the next step S202.
In step S202, a vehicle speed determination process for determining whether or not there is an output from the vehicle body speed sensor 8 is performed. When it is determined in step S202 that there is no output from the vehicle speed sensor, as shown in the next step S203, the vehicle speed sensor 8 is determined to be faulty, the display means 10 is operated, and step S201 is performed. Return to In step S202,
If it is determined that there is an output from the vehicle speed sensor, the process immediately returns to the first step S201.

If there is no wheel speed sensor detecting a speed equal to or higher than the first reference value in the first effective sensor detection process in step S201, the next step S201 is executed.
Proceed to 211. In step S211, an axis unit effective sensor detection is performed to determine whether or not any of the wheel speed sensors 3 and 4 mounted on each wheel on the front axle of the vehicle detects a speed equal to or higher than a second reference value. Perform processing. Then, when it is determined that the output of each of the wheel speed sensors 3 and 4 is equal to or less than the second reference value, the process immediately returns to the first step S201.

In step S211, the wheel speed sensors 3,
If it is determined that any one of the four speeds is equal to or higher than the second reference value, the wheel speed sensors 5 and 6 mounted on the respective wheels on the rear axle of the vehicle are subjected to the second speed. Axis effective sensor detection processing is performed to determine whether or not there is a speed that is higher than or equal to the reference value. Then, step S212
When it is determined that any one of the wheel speed sensors 5 and 6 outputs a speed equal to or higher than the second reference value,
Proceed to step S202.

In step S212, the wheel speed sensors 5,
In any of the cases 6, when the sensor output is determined to be equal to or less than the second reference value, the process returns to the first step S201.

The method of detecting a failure of a vehicle speed sensor executed by the sensor failure detection device 1 described above monitors output signals of a vehicle speed sensor 8 and a plurality of wheel speed sensors 3, 4, 5, and 6 mounted on a vehicle. When these output signals meet predetermined conditions, the vehicle body speed sensor 8 is determined to be faulty, and the number of output signals to be monitored is smaller than that of a conventional signal for monitoring the operating states of clutches and transmissions. In addition, signal processing for detecting a failure of the vehicle speed sensor 8 is simplified. Further, since the operation state of the transmission is not monitored, the transmission can be used commonly for an automatic transmission vehicle and a manual transmission vehicle. Therefore, it is possible to reduce the cost of realizing the device.

Further, as compared with the conventional one which monitors the operating state of the clutch and the transmission, the types of sensors and the like used for failure detection are limited to two types, ie, a wheel speed sensor and a vehicle speed sensor, and the number of sensors is small. A decrease in reliability due to a failure of a sensor or the like used for failure detection can be prevented, operation reliability can be improved, and highly reliable failure detection can be realized at low cost.

Further, in the case of the present embodiment, two reference values, a first reference value and a second reference value, are set as speed values to be used for failure determination criteria, and the first reference value is set. Since the failure diagnosis is performed even with the second reference value smaller than the value,
For example, even during maintenance work such as tire replacement or when traveling at extremely low speed, highly reliable failure detection can be performed on the vehicle body speed sensor 8.

In the above-described embodiment, a case has been described in which the vehicle speed sensor 8 for detecting the average speed of the drive shaft of the vehicle is used as the vehicle speed sensor 8 for detecting the moving speed of the vehicle. However, the sensor used as the vehicle body speed sensor 8 is not limited to the above-described embodiment. For example, a ground sensor or the like that detects the ground speed of the vehicle body can be used.

In this embodiment, the wheel speed sensors 3, 4, 5, and 6 are used for an antilock brake system, and the vehicle speed sensor 8 is used for a braking force holding system. However, the use of the vehicle speed sensor failure detection method of the present invention is not limited to a vehicle having both an anti-lock brake system and a braking force holding system. As long as the vehicle includes the above-described wheel speed sensor for each wheel and a vehicle speed sensor such as a vehicle speed sensor that detects the movement of the vehicle, it can be used in a vehicle having another braking function instead of the braking force holding system. It is possible.

[0026]

According to the vehicle body speed sensor failure detecting method of the present invention, the output signals of the vehicle body speed sensor and the plurality of wheel speed sensors mounted on the vehicle are monitored, and these output signals are set under a predetermined condition. When the vehicle speed sensor is determined to be faulty, the output signal to be monitored is smaller than that of the conventional one that monitors the operating state of the clutch and transmission. Processing becomes simple. Further, since the operation state of the transmission is not monitored, the transmission can be used commonly for an automatic transmission vehicle and a manual transmission vehicle. Therefore, it is possible to reduce the cost of realizing the device. Also, as compared with the conventional one that monitors the operating state of the clutch and the transmission, the number of types of sensors and the like used for failure detection can be reduced, so that the decrease in reliability due to the failure of the sensors and the like used for failure detection is reduced. Thus, the operation reliability can be improved, and highly reliable failure detection can be realized at low cost.

Also, in the case of the structure according to claim 2,
2. A system for monitoring output signals of a vehicle speed sensor and a plurality of wheel speed sensors mounted on a vehicle, and determining that the vehicle speed sensor is out of order when the output signals meet predetermined conditions. As in the case of the configuration described in, the signal processing for detecting the failure of the vehicle body speed sensor is simplified, and at the same time, it can be used commonly for automatic transmission vehicles and manual transmission vehicles,
The cost of equipment can be reduced. Further, as in the case of the configuration of the first aspect, the number of sensors and the like used for failure detection can be reduced, so that operation reliability can be improved and highly reliable failure detection can be realized at low cost. Can be. According to the second aspect of the present invention, two reference values, a first reference value and a second reference value, are set as speed values to be used for a failure determination criterion. In order to perform the failure diagnosis with the second reference value where
Even during maintenance work such as tire replacement or when traveling at extremely low speed, highly reliable failure detection can be performed on the vehicle body speed sensor.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of a sensor failure detection device that performs a vehicle body speed sensor failure detection method according to the present invention.

FIG. 2 is a flowchart illustrating a processing procedure of a vehicle body speed sensor failure detection method performed by the sensor failure detection device illustrated in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sensor failure detection device 3-6 Wheel speed sensor 8 Body speed sensor 10 Display means 12 Control unit

Claims (2)

[Claims] 1. A method for detecting a failure of a vehicle speed sensor in a vehicle provided with a wheel speed sensor for detecting a rotational speed of a wheel for each wheel and having a vehicle speed sensor for detecting a moving speed of a vehicle body. An effective sensor detection process for determining whether there is a wheel speed sensor that outputs a speed equal to or higher than a reference value among a plurality of wheel speed sensors, and a vehicle speed determination process for determining whether there is an output from the vehicle body speed sensor. When at least one wheel speed sensor that outputs a speed equal to or higher than the reference value is present in the effective sensor detection process, and it is determined in the vehicle speed determination process that there is no output from the vehicle speed sensor, And detecting a failure of the vehicle body speed sensor. 2. A method for detecting a failure of a vehicle speed sensor in a vehicle provided with a wheel speed sensor for detecting a rotational speed of a wheel for each wheel and having a vehicle speed sensor for detecting a moving speed of the vehicle body. A first reference value and a second reference value smaller than the first reference value are set as reference values of the wheel speed, and a wheel speed detecting a speed equal to or higher than the first reference value A first effective sensor detection process for determining the presence / absence of a sensor is performed. If there is no wheel speed sensor that outputs a speed equal to or higher than the first reference value in the first effective sensor detection process,
An axis unit effective sensor detection process for determining the presence or absence of a wheel speed sensor outputting a speed equal to or higher than the second reference value for each wheel axle; a vehicle speed determination process for determining the presence or absence of an output of the vehicle body speed sensor There is at least one wheel speed sensor for each wheel axle that outputs a speed equal to or higher than the second reference value in the shaft unit effective sensor detection process, and the vehicle body in the vehicle speed determination process A failure detection method for a vehicle body speed sensor, comprising: determining that the vehicle body speed sensor has failed when it is determined that there is no output from the speed sensor.