JPH0740042B2 - Longitudinal acceleration sensor abnormality detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is used as a sensor for providing longitudinal acceleration information in a control system such as an antilock brake control device, a front / rear wheel drive force distribution control device, and an active suspension control device. The present invention relates to a longitudinal acceleration sensor abnormality detection device.

(Prior Art) Conventionally, as a front-rear acceleration output value correction device applied to an antilock brake control device, for example, Japanese Patent Laid-Open No. 63-2416
The device described in Japanese Patent No. 6 is known.

In this conventional source, the longitudinal acceleration detection value obtained from the longitudinal acceleration sensor and the longitudinal acceleration calculation value obtained by differentiating the vehicle speed from the vehicle speed sensor are compared at the time of low acceleration / deceleration, and the difference between the two values is determined. A device is shown in which the longitudinal acceleration detected value is shift-corrected to match the longitudinal acceleration calculated value at the above times, and the longitudinal acceleration correction value obtained by this correction processing is used as the control information of the antilock brake control device.

(Problems to be Solved by the Invention) However, such a conventional longitudinal acceleration output value correction device is a device on the assumption that the longitudinal acceleration sensor is normal, and for example, when traveling on an inclined road surface. This is an effective device when the longitudinal acceleration detection value is output with an offset error due to the inclination component being included in the longitudinal acceleration detection value, but the longitudinal acceleration detection value from the sensor always outputs a constant value. Further, when the so-called longitudinal acceleration sensor is abnormal, such as outputting a detection value that changes regardless of the vehicle longitudinal acceleration, the control system using the longitudinal acceleration detection value as control information is significantly affected.

For example, in the anti-lock brake control device, the vehicle speed is estimated by integrating the front-rear speed detection value, and the brake fluid pressure is increased based on the estimated vehicle speed and the wheel speed.
Since the slip ratio of each wheel, which is the criterion for decompression and holding, is calculated, the slip ratio is not accurate, and the braking distance is extended due to insufficient brake fluid pressure, and the wheel lock etc. due to excessive brake fluid pressure. Allow it to occur.

Therefore, as a device for detecting an abnormality in the longitudinal acceleration sensor, a device in which two or more longitudinal acceleration sensors are provided and the abnormality is detected by comparing detected values from these sensors is considered, but in this case, high cost is required. Will be.

The present invention has been made in view of the above-mentioned problems, and when the abnormality of the longitudinal acceleration sensor applied to various vehicle control systems is accurately detected by a cost-effective device, and the abnormality is left as it is. The challenge is to minimize the impact on the control system that occurs in the system.

(Means for Solving the Problem) In order to solve the above problems, in the longitudinal acceleration sensor abnormality detection device of the present invention, the lateral acceleration sensor abnormality is based on the longitudinal acceleration detection value during non-acceleration / deceleration operation as the basis for abnormality determination. Was used as a device for detecting.

That is, as shown in the claim correspondence diagram of FIG. 1, a longitudinal acceleration sensor a for outputting a longitudinal acceleration detection value corresponding to the longitudinal acceleration of the vehicle by an electric signal, and an acceleration / deceleration operation detecting means b for detecting an acceleration / deceleration operation of the vehicle. And the acceleration / deceleration operation detection means b
When it is detected that the vehicle is in the non-acceleration / deceleration operation, the longitudinal acceleration is detected when the longitudinal acceleration detection value from the longitudinal acceleration sensor a outputs a value corresponding to the acceleration / deceleration of the vehicle for a predetermined time. A sensor abnormality detecting means c for detecting that the sensor a is abnormal, and a failsafe operating means d for performing a predetermined failsafe operation when a sensor abnormality signal is output from the sensor abnormality detecting means c. Characterize things.

(Operation) When the sensor abnormality is detected by the sensor abnormality detection means c, when the acceleration / deceleration operation detection means b detects non-acceleration / deceleration operation, the longitudinal acceleration detection value from the longitudinal acceleration sensor a is A sensor abnormality signal is output by satisfying an abnormality determination condition that a state in which a value corresponding to acceleration / deceleration is output continues for a predetermined time, and a fail-safe operating means d issues a warning or a predetermined control such as system control stop. Fail-safe operation is performed.

Therefore, the abnormality of the longitudinal acceleration sensor a applied to various vehicle control systems is accurately detected by a cost-effective device that does not use a plurality of sensors, and the control system occurs when the abnormality is left unattended. Can be minimized.

First Embodiment First, the configuration will be described.

FIG. 2 is an overall system diagram including a braking system to which a four-wheel anti-lock brake control system having a longitudinal acceleration sensor abnormality detection device of the embodiment is applied and a drive system to which a torque split control system of a four-wheel drive vehicle is applied. Yes, first
The configuration of the torque split control system will be described.

The vehicle to which the torque split control system of the embodiment is applied is a rear-wheel-based four-wheel drive vehicle, and its drive system includes an engine 1, a transmission 2, a transfer input shaft 3, a rear propeller shaft 4, a rear differential 5, and a rear differential. It is equipped with wheels 6, transfer output shaft 7, front propeller shaft 8, front differential 9, and front wheels 10. The engine driving force that has passed through the transmission 2 is directly transmitted to the rear wheels 6, and the front wheels drive system to the front wheels 10. Is transmitted via the transfer clutch device 11 provided between the transfer input / output shafts 3 and 7.

A torque split control system that optimally controls the driving force distribution between the front and rear wheels while achieving both driving performance and steering performance is achieved by the transfer clutch device 11 (for example, the Japanese Patent Application No. Sho 63-3253
(See the description and drawings of No. 79), a control oil pressure generator 20 that generates a control oil pressure Pc that is a clutch engagement force, and information from various input sensors 30 to a solenoid valve 28 provided in the control oil pressure generator 20. A torque split control section 40 of the control unit C / U that outputs a predetermined solenoid drive current _IETS based on the above, and an alarm lamp 50 that lights up when various abnormalities occur.

The hydraulic control device 20 controls a motor 22 that is driven or stopped by a relief switch 21, a hydraulic pump 24 that is driven by the motor 22 to suck up from a reservoir tank 23, and a pump discharge pressure (primary pressure) from the hydraulic pump 24. An accumulator 26 that stores via the check valve 25 and a solenoid valve 28 that adjusts the line pressure (secondary pressure) from the accumulator 26 to a predetermined control hydraulic pressure Pc by the solenoid drive current I _ETS from the torque split control unit 40. The control oil Pc is supplied to the clutch port after passing through the control oil pressure pipe 29.

As the various input sensors 30, as shown in the block diagram of the system electronic control system of FIG.
a, right front wheel rotation sensor 30b, left rear wheel rotation sensor 30c, right rear wheel rotation sensor 30d, accelerator opening sensor 30e, lateral acceleration sensor 30
f, a drive current sensor 30g, a control hydraulic pressure sensor 30h, and a front wheel shaft torque sensor 30i.

As shown in the block diagram of the system electronic control system of FIG. 3, the torque split control unit 40 includes a left front wheel speed calculation circuit.
40a, right front wheel speed calculation circuit 40b, left rear wheel speed calculation circuit 40c, right rear wheel speed calculation circuit 40d, front wheel speed calculation circuit 40e, rear wheel speed calculation circuit 40f,
Rotational speed difference calculation circuit 40g, lateral acceleration output value correction circuit 40h, gain calculation circuit 40i, fastening force calculation circuit 40j, dither signal generation circuit 40k, solenoid drive circuit 40l, rotational speed difference output value abnormality detection circuit 40m, lateral acceleration sensor It has an abnormality detection circuit 40n, a clutch abnormality detection circuit 40o, an abnormality determination threshold value circuit 40p, and a fail-safe circuit 40q.

As the alarm lamp 50, as shown in the block diagram of the system electronic control system of FIG. 3, there are a rotational speed difference abnormality alarm lamp 50a, a lateral acceleration sensor abnormality alarm lamp 50b, and a clutch abnormality alarm lamp 50c.

Next, the configuration of the four-wheel antilock brake control system will be described with reference to FIGS. 2 and 3.

The braking system to which the four-wheel anti-lock brake control system of the embodiment is adapted is, as shown in FIG.
60, booster 61, master cylinder 62, actuator 63, wheel cylinders 64a, 64b, 64c, 64d, brake piping 65, 66a, 6
It has 6b, 66c and 66d.

Then, by controlling the braking force so that the slip ratio of each wheel obtained from the vehicle body speed and each wheel speed converges to around 0.15 to 0.3, wheel locking is prevented during sudden braking or low u road braking. Wheel antilock brake control system
The actuator 63 having a three-position switching solenoid valve and a hydraulic pump motor, and a control unit C for outputting to the actuator 63 drive commands for increasing, reducing, and holding the brake fluid pressure based on information from various input sensors 30. / U anti-lock brake control unit 70, and an alarm lamp 50 that lights up in the event of various abnormalities.

The various input sensors 30 may be the longitudinal acceleration sensor 30 as shown in the block diagram of the system electronic control system of FIG.
The left front wheel rotation sensor 30a, the right front wheel rotation sensor 30b, the left rear wheel rotation sensor 30c, the right rear wheel rotation sensor 30d, etc., which have j and a stop lamp switch 30k, and which provide necessary information, are shared with the torque split control system. .

As shown in the block diagram of the system electronic control system of FIG. 3, the antilock brake control unit 70 includes a vehicle speed calculation circuit 70a, an antilock control circuit 70b, an actuator drive circuit 70c, a longitudinal acceleration sensor abnormality detection circuit 70c, It has a fail-safe circuit 70d.

The alarm lamp 50 includes a longitudinal acceleration sensor abnormality alarm lamp 50d.

The longitudinal acceleration sensor abnormality detection device of the embodiment for detecting abnormality of the longitudinal acceleration sensor 30j is
The stop lamp switch 30k, the longitudinal acceleration sensor abnormality detection circuit 70d, the fail-safe circuit 70e, and the alarm lamp 50d.

Next, the operation will be described.

FIG. 4 is a flow chart showing the flow of the brake hydraulic pressure control operation in the antilock brake control unit 70, and the flow of the control operation will be described in order of steps.

In step 80, it is judged whether or not the stop lamp switch 30k is ON, that is, whether or not the braking operation is performed by depressing the brake pedal.

In step 81, it is judged whether the operation is normal based on the result of the abnormality detection process of the longitudinal acceleration sensor 30j described later. If the longitudinal acceleration sensor 30j is abnormal, step 82
When the longitudinal acceleration sensor 30j is normal and the predetermined antilock brake control start condition is satisfied, the process proceeds to step 83 and subsequent steps.

In step 82, as a fail-safe operation when the longitudinal acceleration sensor 30j is abnormal, the lighting command is output to the alarm lamp 50d along with the stop of the antilock brake control.

Even if the anti-lock brake control is stopped, the brake fluid pressure from the master cylinder 62 is applied to each wheel cylinder 64a, 64a.
Normal braking for delivery to b, 64c, 64d is ensured.

In step 83, left front wheel speed V _WFL , right front wheel speed V _WFR , left rear wheel speed
V _WRL , right rear wheel speed V _WRR and longitudinal acceleration detection value Xg are read.

In step 84, the left front wheel slip ratio S _FL is calculated by the following formula based on the longitudinal acceleration detection value Xg and the left front wheel speed V _WFL .

V _B = ∫ | Xg | dt (V _B ; estimated vehicle speed) In step 85 and step 86, the left front wheel slip ratio S _FL
Is compared with the slip ratio thresholds S ₀ and S ₁ , and when S ₀ <S _FL <S ₁ at which the braking resistance coefficient (braking force) is maximized, the brake fluid pressure holding command is output in step 87. When S _FL ≧ S ₁ where the wheels tend to lock, the brake fluid pressure reduction command is output in step 88 and S _FL becomes insufficient for braking force.
When ≦ S ₀ , the brake fluid pressure increase command is output in step 89.

The operations in steps 84 to 89 are similarly performed independently for each of the right front wheel, the left rear wheel, and the right rear wheel.

FIG. 5 shows the first process performed by interrupt processing at regular time intervals (for example, every 10 msec) during the brake fluid pressure control operation.
It is a flow chart which shows the flow of the longitudinal acceleration sensor abnormality detection operation of an example, and explains the flow of detection operation in order of each step.

In step 90, the longitudinal acceleration detection value Xg from the longitudinal acceleration sensor 30j and the switch signal (SSW) from the stop lamp switch 30k are read.

In step 91, it is determined whether the switch signal (SSW) from the stop lamp switch 30k as the deceleration operation detection means is OFF, that is, whether the brake is not operated.

In step 92, the absolute value | Xg | of the longitudinal acceleration detection value Xg is
It is determined whether or not the sensor failure determination threshold value Xg ₀ (for example, 0.3g) set based on a value corresponding to the time of deceleration of the vehicle is abnormal.

Then, when the conditions of step 91 and step 92 are satisfied at the same time, that is, when the longitudinal acceleration detection value Xg shows a value corresponding to deceleration of the vehicle even during the brake operation, there is a possibility that the sensor is abnormal. As high as step 93
Then, the processing proceeds to step S8, where the timer value T is added by T + 10 (msec).

On the other hand, when at least one of the conditions of steps 91 and 92 is not satisfied, it is estimated that the sensor is normal, the process proceeds to step 94, and a process of setting the timer value T to 0 is performed.

In step 95, it is determined whether or not the timer value T is equal to or more than the set timer value T ₀ (for example, 100 msec), and when T <T ₀ , the process proceeds to step 96, and the determination result that the longitudinal acceleration sensor 30j is normal is output, and , T ≧ T _0, the routine proceeds to step 97, where the determination result that the longitudinal acceleration sensor 30j is abnormal is output.

Abnormality As explained, the longitudinal acceleration detection value Xg from the longitudinal acceleration sensor 30j always outputs a constant value, or
Longitudinal acceleration detection value Xg that changes regardless of vehicle longitudinal acceleration
When the sensor is abnormal, for example, when the brake is not operated, the longitudinal acceleration detection value Xg continues to remain at a value corresponding to the vehicle deceleration, and the process proceeds from step 81 to step 82. , The anti-lock brake control is stopped and the alarm lamp 50d is turned on to perform a fail-safe operation to inform the driver that the longitudinal acceleration sensor 30j is abnormal.After that, a sensor error occurs due to inspection or replacement of the longitudinal acceleration sensor 30j. Can be dealt with.

Therefore, the longitudinal acceleration sensor abnormality detecting device of the first embodiment has the following features.

Since the non-deceleration operation detection, which is the basis of the abnormality determination, is obtained based on the signal from the stop lamp switch 30k provided in advance in the anti-lock brake control system, the abnormality of the longitudinal acceleration sensor 30j is detected by a plurality of longitudinal acceleration sensors. It can be accurately detected with a cost-effective device that is not used.

If the longitudinal acceleration sensor 30j is abnormal, the antilock brake control is immediately stopped and the driver is notified of the abnormality by lighting the alarm lamp 50d.Antilock brake control system that occurs when the abnormality is left as it is. Can be minimized. The vehicle body speed V _B estimated by integrating the longitudinal acceleration detection value Xg serves as a reference for obtaining the slip ratio S of each wheel. Therefore, if the slip ratio S is not accurate, the brake fluid pressure A shortage extends the braking distance, and an excessive brake fluid pressure has an effect such as allowing wheel locks to occur.

Second Embodiment Next, a second embodiment of the longitudinal acceleration sensor abnormality detection device will be described.

The second embodiment apparatus is an example in which the longitudinal acceleration sensor abnormality is detected by the non-deceleration operation detection in which the first embodiment apparatus is not performing the brake operation, whereas the non-accelerator operation detection in which the accelerator operation is not performed is detected. This is an example of detecting an abnormality of the longitudinal acceleration sensor by.

The structure of the apparatus is the same as that of the apparatus of the first embodiment except that the accelerator pedal switch 30l shown in FIG.

FIG. 6 is a flow chart showing the flow of the longitudinal acceleration sensor abnormality detection operation of the second embodiment performed by interrupt processing at regular time intervals (for example, every 10 msec). The flow of detection operation will be described in order of steps.

In step 100, the longitudinal acceleration detection value Xg from the longitudinal acceleration sensor 30j and the switch signal (ASW) from the accelerator pedal switch 30l are read.

In step 101, it is judged whether or not the switch signal (ASW) from the accelerator pedal switch 30l as the acceleration operation detecting means is OFF, that is, whether or not the accelerator is not being operated.

In step 102, the absolute value of the longitudinal acceleration detection value Xg | Xg |
Is greater than or equal to the sensor failure determination threshold value Xg ₁ (for example, 0.1 g) set based on the value corresponding to the vehicle deceleration.

If the conditions of step 101 and step 102 are satisfied at the same time, that is, if the longitudinal acceleration detection value Xg shows a value corresponding to the acceleration of the vehicle even when the accelerator is not operated, it is possible to exceed the sensor. Since the property is high, the process proceeds to step 103, and a process of adding the timer value T by T + 10 (msec) is performed.

On the other hand, if any of the conditions in steps 101 and 102 is not satisfied, it is presumed that the sensor is normal and step 10
Proceeding to step 4, processing for setting the timer value T to 0 is performed.

The steps 105 to 107 are the steps of the first embodiment.
Since this is a step corresponding to steps 95 to 97, a description thereof will be omitted.

Third Embodiment Next, a longitudinal acceleration sensor abnormality detection device of the third embodiment will be described.

The third embodiment apparatus is also an example in which the longitudinal acceleration sensor abnormality is detected by the non-acceleration operation detection in which the accelerator operation is not performed, which is the vehicle acceleration state, similarly to the second embodiment apparatus.

With regard to the device configuration, the accelerator pedal switch 30l is used in the second embodiment device while the accelerator opening sensor 3 is used.
The only difference is that 0e is used as the acceleration operation detection means, and a detailed description is omitted.

FIG. 7 is a flow chart showing the flow of the longitudinal acceleration sensor abnormality detection operation of the third embodiment performed by the interrupt processing at regular time intervals (for example, every 10 msec), and the flow of the detection operation will be described step by step.

In step 110, the longitudinal acceleration detection value Xg from the longitudinal acceleration sensor 30j and the accelerator opening detection value A from the accelerator opening sensor 30e are read.

In step 111, whether the accelerator opening degree detection value A from the accelerator opening degree sensor 30e as the acceleration operation detecting means is equal to or smaller than the accelerator opening degree set value A _{0 which} is a small value that becomes a threshold value between the acceleration operation and the non-acceleration operation. That is, it is determined whether or not the non-acceleration operation is being performed.

Incidentally, steps 112 to 117 are the steps of the second embodiment.
Since this is a step corresponding to steps 102 to 107, its explanation is omitted.

Although the embodiment has been described above with reference to the drawings, the specific configuration and control contents are not limited to this embodiment.

For example, although an example of the longitudinal acceleration sensor abnormality detection device applied to the anti-lock brake control system is shown in the embodiment, various vehicle-mounted control systems using the longitudinal acceleration sensor as an input sensor, for example, a torque split control system and an active suspension. Of course, it can be applied to a control system, a four-wheel steering control system, and the like.

Further, in the embodiment, the example in which the control system applied as the fail-safe operation is stopped and the alarm lamp is turned on is shown. However, “alarm buzzer sounds”, “fix actuator to safe side”, “gradually” It is also possible to combine one or more of various fail-safe operations such as "to shift to the safe side state".

In addition, in the embodiment, in detecting the abnormality of the longitudinal acceleration sensor, an example of non-deceleration operation (first embodiment) and non-acceleration operation (second and third embodiments) is shown. It is also possible to detect the abnormality of the longitudinal acceleration sensor by the non-acceleration operation.

The acceleration / deceleration operation detecting means may be any means capable of detecting the acceleration / deceleration operation. For example, brake fluid pressure or engine intake pressure may be used in addition to those mentioned in the embodiments. .

(Advantages of the Invention) As described above, in the longitudinal acceleration sensor abnormality detection device of the present invention, the abnormality in the lateral acceleration sensor is detected based on the longitudinal acceleration detection value during non-acceleration / deceleration operation as the basis for abnormality determination. Since it is a device, it is possible to accurately detect abnormalities of the longitudinal acceleration sensor applied to various vehicle control systems with a cost-effective device, and to minimize the influence on the control system that occurs when the abnormality is left unattended. The effect that can be obtained is obtained.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to the claims showing a longitudinal acceleration sensor abnormality detection device of the present invention, and FIG. 2 is an overall schematic diagram showing a drive system, a braking system and a control system of a four-wheel drive vehicle to which the embodiment device is applied,
FIG. 3 is a block diagram showing an electronic control system to which the embodiment apparatus is applied, FIG. 4 is a flowchart showing a flow of an antilock brake control operation, and FIG. 5 is a longitudinal acceleration sensor abnormality detection operation of the first embodiment. FIG. 6 is a flowchart showing the flow of the longitudinal acceleration sensor abnormality detection operation of the second embodiment, and FIG. 7 is a flowchart showing the longitudinal acceleration sensor abnormality detection operation of the third embodiment. a: longitudinal acceleration sensor b: acceleration / deceleration operation detection means c: sensor abnormality detection means d: fail-safe operation means

Claims (1)

[Claims] 1. A longitudinal acceleration sensor for outputting a longitudinal acceleration detection value according to a longitudinal acceleration of the vehicle by an electric signal, an acceleration / deceleration operation detecting means for detecting an acceleration / deceleration operation of the vehicle, and a non-acceleration operation for detecting the acceleration / deceleration operation of the vehicle. When it is detected that it is during deceleration operation, if the longitudinal acceleration detection value from the longitudinal acceleration sensor outputs a value equivalent to the acceleration / deceleration of the vehicle for a predetermined period of time, the longitudinal acceleration sensor is abnormal. A longitudinal acceleration sensor characterized by comprising: a sensor abnormality detecting means for detecting that there is; and a failsafe operating means for performing a predetermined failsafe operation when a sensor abnormality signal is output from the sensor abnormality detecting means. Anomaly detection device.