JP3186479B2 - Abnormality detection device for vehicle speed sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an abnormality detecting device for a vehicle speed sensor.

[0002]

2. Description of the Related Art In an automobile or the like, a detection signal of a vehicle speed sensor is used for controlling, for example, a power steering system or a rear wheel steering system. However, the signal of the vehicle speed sensor may not be input to the control system due to a failure of the vehicle speed sensor or a disconnection of a signal line for sending the output of the vehicle speed sensor. It is necessary to perform fail-safe control for stopping various operation controls of the vehicle.

[0003] Conventionally, in order to detect an abnormality of a vehicle speed sensor, operating states such as an engine speed, a parking brake, a foot brake, a shift position of a transmission, and the like are detected. In some cases, it is determined whether the vehicle speed sensor is abnormal based on a detection signal of the vehicle speed sensor when the vehicle is running (Japanese Patent Laid-Open No.
1-21-2454).

[0004]

However, in such a conventional vehicle speed sensor abnormality detecting device, when the vehicle is traveling uphill, the braking by the parking brake or the foot brake is released, and the rotational force of the engine is used. Even in the creep state where the vehicle is stopped via the torque converter, it is determined that the vehicle is traveling and the abnormality diagnosis of the vehicle speed sensor is performed, and it is possible to erroneously diagnose such a creep state as having the abnormality of the vehicle speed sensor. There is.

In order to determine whether or not the vehicle is running, an input interface circuit, a vehicle harness, and the like are used to process a plurality of signals for detecting operating states such as a parking brake, a foot brake, and a shift position of a transmission. Increases, leading to higher costs.

An object of the present invention is to solve the above-mentioned problems and to provide an apparatus capable of detecting an abnormality of a vehicle speed sensor using only a detection signal of an engine speed.

[0007]

[0008]

Means for Solving the Problems] abnormality detection device of the vehicle speed sensor according to claim 1, as shown in FIG. 4, a vehicle speed sensor 31 for detecting a vehicle speed, engine speed sensor 32 for detecting an engine rotational speed When, a first reference value setting means 33 for setting a high first reference value N ₁ than idle speed, eye
Higher than the $ rpm, lower than the first reference value N ₁ second reference
A second reference value setting means 37 for setting the value N _2, after the engine speed has increased to the first reference value N ₁ or more, diagnostic speed region determining operating conditions increasing the second reference value N ₂ or more The determining means 38 determines that the engine speed is less than a predetermined time T _S.
Second reference value N ₂ or more after rising to a first reference value N ₁ or more
Judgment is made when the diagnostic conditions are satisfied where rising operating conditions continue
The vehicle includes a diagnosis condition determination unit 39 and an abnormality determination unit 40 that determines whether the vehicle speed sensor 31 has an abnormality based on a detection signal of the vehicle speed sensor 31 when the diagnosis condition is satisfied.

[0009]

[0010]

[0011]

[0012]

In the abnormality detecting device of the vehicle speed sensor according to the action] claim 1, to determine the operating state of the engine rotational speed does not increase beyond the first reference value N ₁ even once at the time of warm-up, the engine during warm-up rotational speed is determined to parked lower operating conditions than the second reference value N _2, without abnormality diagnosis of the vehicle speed sensor 31, it determines that the traveling state engine speed is at a second reference value N ₂ or more operating conditions Then, abnormality diagnosis of the vehicle speed sensor 31 is performed until the predetermined time Ts elapses.

[0013] For example, the time when the vehicle is shorter than the predetermined time Ts
The engine speed is the first reference value N ₁Rise above
After finishing the speed, the engine speed is reduced to the first reference value N₁Than
Judgment of running condition even under cruising conditions
Thus, abnormality of the vehicle speed sensor 31 can be diagnosed.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 denotes an engine, and an engine control unit 4 comprising a microcomputer for controlling the operation of the engine 1 is provided.

The engine control unit 4 receives detection signals from an air flow meter 5 for detecting an intake air amount, a rotation speed sensor 6 for detecting an engine rotation speed N from a crank angle, and the like, and performs fuel injection based on these signals. The control of the fuel injection amount from the valve 7 is performed.

Reference numeral 2 denotes an automatic transmission, and a transmission control unit 3 for controlling the operation of the automatic transmission 2 is provided.

The transmission control unit 3 includes a rotation speed sensor 6, a throttle sensor 8 for detecting a throttle valve opening Tvo, a vehicle speed sensor 9 for detecting a vehicle speed Vsp from a rotation speed of an output shaft of the automatic transmission 2, and the like. Detected signals are input, and shift control is performed via shift solenoids 11 and 12 based on these detected signals.

The detection signal from the vehicle speed sensor 9 is also input to the control unit 15 of the power steering system. The control unit 15 controls the assist hydraulic pressure of the steering according to the vehicle speed Vsp to appropriately adjust the steering force of the steering.

The detection signal from the vehicle speed sensor 9 is also input to the control unit 16 of the rear wheel steering system.
The control unit 16 steers rear wheels according to the vehicle speed Vsp and the steering angle.

The signal of the vehicle speed sensor 9 may not be input to the transmission control unit 4 or the like due to the failure of the vehicle speed sensor 9 or the disconnection of the signal line for sending the output of the vehicle speed sensor 9. It is necessary to perform fail-safe control that detects an abnormality of the sensor 9 and stops various operation controls of the vehicle according to the vehicle speed Vsp.

Therefore, in order to detect an abnormality of the vehicle speed sensor 9, the transmission control unit 3 controls the vehicle speed sensor 9.
Of the vehicle speed sensor 9 is determined based on the detection signal Vsp and the detection signal N of the rotation speed sensor 6.

The control unit 3, the first reference value N ₁ or more operating condition of the engine rotational speed N is higher than the idle rotational speed is determined while the vehicle is running, the engine speed is the first reference value N ₁ or more operating conditions If the detection signal of the vehicle speed sensor 9 is not input during the period of the predetermined time Ts, it is determined that the vehicle speed sensor 9 has failed.

The engine control unit 3 controls the idle speed of the engine 1 to a preset target value via an auxiliary air amount control valve (not shown). The target idle speed is determined according to the cooling water temperature, the operating state of the air conditioner (vehicle interior cooling system), and the shift position of the transmission 2.

The first reference value N ₁ is set to a value larger than the maximum value of the target idle speed. In this embodiment, respectively set the maximum value of the target idle speed 800 rpm, the first reference value N ₁ to 1800 rpm.

The predetermined time Ts is set to 10 seconds, which is longer than the expected time for so-called idling, in which the clutch is disengaged to increase the engine speed.

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

The control unit 3 determines that the engine speed N exceeds a first reference value N ₁ higher than the idle speed,
During engine rotational speed N is a first reference value higher than the low idle speed than N ₁ second reference value N ₂ or more operating conditions is determined that while the vehicle is running, that the operating condition continues for a predetermined time Ts, the vehicle speed When the detection signal of the sensor 9 is not input, it may be determined that the vehicle speed sensor 9 has failed.

The first reference value N ₁ and the second reference value N ₂ are set to values larger than the maximum value of the target idle speed. In this embodiment, the maximum value of the target idle speed is set to 800 rpm
m, the first reference value N ₁ is 1800 rpm, and the second reference value N ₂ is the maximum idle speed 1000 rpm after warm-up.
Set to each.

The flow chart of FIG . 2 shows the contents of control for detecting an abnormality of the vehicle speed sensor 9 and is executed by the control unit 4 at regular intervals.

[0043] First, in step 11, it is determined whether the engine rotational speed N is the first reference value N ₁ or more.

[0044] If the engine speed N is determined to be lower than the first reference value N _1, 1 proceeds to step 12, after the start of the ignition switch (IGN) is turned ON
At times it determined whether the engine speed N becomes the first reference value N ₁ or more. It is also possible to change the step 12 to determine "whether or becomes the first reference value N ₁ or more continuously the engine speed N is 3 seconds or more."

If it is determined that the engine speed N has not reached the first reference value N ₁ or more even once after the start, it is determined that the vehicle has not been warmed up and the vehicle is stopped, and the process proceeds to step 12. Clear the timer value T.

On the other hand, the engine speed N
Or If is it is determined that becomes the first reference value N ₁ or more, it is determined that the warm-up is completed, it is the engine rotational speed N is the second reference value N ₂ or proceeds to Step 14 Determine whether

If it is determined in step 14 that the engine speed N has become equal to or greater than the first reference value N ₁ and then equal to or greater than the second reference value N ₂ , or
If the engine speed N is determined to have become the first reference value N ₁ or more at 1, it is determined that the traveling, the process proceeds to step 16 and subsequent routine, the detection signal from the vehicle speed sensor 9 are input Is determined.

If it is determined that the detection signal from the vehicle speed sensor 9 has been input, it is determined that the vehicle speed sensor 9 is operating normally, and the routine proceeds to step 17, where the timer value T is cleared.

Meanwhile, if the detection signal from the vehicle speed sensor 9 is judged not to be inputted, the routine proceeds to step 18 and 19, or the engine speed N is first reference value N ₁ or more, the engine speed N timer value but measured from after once first reference value N ₁ or more is determined that either a second reference value N ₂ or more, and a driving state detection signal is not inputted from the vehicle speed sensor 9 It is determined whether T has become equal to or greater than a predetermined value Ts.

If it is determined that the timer value T has become equal to or greater than the predetermined value Ts, it is determined that an abnormality has occurred in the vehicle speed sensor 9, and the routine proceeds to step 20, where various operation controls of the vehicle corresponding to the vehicle speed Vsp are performed. Fail-safe control to output a command to stop the operation.

With the above configuration, the engine speed N
Is determined to be a warm-up state in which the engine speed never rises above the first reference value of 1800 rpm, and an operation state in which the engine speed is lower than 1000 rpm is determined to be stopped after the warm-up. No diagnosis is performed, and it is determined that the vehicle is running in an operating state where the engine speed is 1000 rpm or more, and abnormality diagnosis of the vehicle speed sensor 9 is performed until 10 seconds elapse.

For example, as shown in FIG. 3 , after the vehicle completes acceleration in less than 10 seconds, the engine speed becomes 1
Even under a driving condition in which the vehicle cruises at a speed lower than 800 rpm, it can be determined that the vehicle is running, and the abnormality of the vehicle speed sensor 9 can be diagnosed.

[0053] Further, it is determined it takes usually cruising in a few seconds accelerated running up proceeds, the "now? First reference value N ₁ or more continuously the engine speed N is at least 3 seconds" at step 12 Thus, similarly to during warm-up, it is possible to prevent erroneous determination of idle-up due to operation of an air conditioner or the like as a running state. Further, even if the engine speed N exceeds 1800 rpm due to idling during warm-up, erroneous determination of fail-safe can be prevented through steps 12 to 14. Even in the creep state where the braking by the foot brake is released and the vehicle is stopped via the torque converter by the torque of the engine 1, if the engine speed N is lower than the first reference value 1800 rpm, the abnormality diagnosis of the vehicle speed sensor 9 is performed. However, it is possible to prevent such a creep state from being erroneously diagnosed as an abnormality of the vehicle speed sensor 9.

With the configuration in which the abnormality of the vehicle speed sensor 9 is continuously diagnosed for 10 seconds, it is erroneously considered that the idling that increases the engine speed for several seconds after the clutch is released is caused by the occurrence of the abnormality of the vehicle speed sensor 9. Diagnosis can be prevented.

[0055]

[0056]

Abnormality detection device of the vehicle speed sensor of claim 1 according to the present invention is an operating condition in which the engine speed does not increase beyond the first reference value N ₁ even once is determined that warming up, during warm engine speed is determined to parked lower operating conditions than the second reference value N ₂ at, without an abnormality diagnosis of the vehicle speed sensor, and during running the engine speed is at a second reference value N ₂ or more operating conditions Judgment is made so that the abnormality diagnosis of the vehicle speed sensor is performed until the predetermined time Ts elapses. Therefore, the abnormality of the vehicle speed sensor is detected using only the detection signal of the engine speed, for example, when the vehicle cruises after sudden acceleration. Even under driving conditions, it is possible to determine that the vehicle is in a running state and diagnose an abnormality of the vehicle speed sensor.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing control contents for diagnosing an abnormality of a vehicle speed sensor.

FIG. 3 is a diagram showing a traveling example of the vehicle.

FIG. 4 is a claim correspondence diagram showing the invention described in claim 1 .

Claims (1)

(57) [Claims] A vehicle speed sensor for detecting a 1. A vehicle speed, an engine speed sensor for detecting an engine speed, a first reference value setting means for setting a high first reference value N ₁ than idle speed, idle speed higher, the second lower than the first reference value N ₁
A second reference value setting means for setting a reference value N _2, after the engine speed has increased to the first reference value N ₁ or more,
Diagnostic determines operating conditions increasing the second reference value N ₂ or more
And rotational speed region determination means, during the predetermined time T _S, the engine speed is the first reference value N ₁ or more
Operating conditions increasing the second reference value N ₂ or more after rising to
Condition judging means for judging the time when the diagnosis condition is satisfied in which the diagnosis is continued
And the vehicle speed based on the detection signal of the vehicle speed sensor when the diagnosis condition is satisfied.
Abnormality determination means for determining whether there is an abnormality in the sensor
When the abnormality detection device of the vehicle speed sensor, comprising the.