JPH02284068A - Abnormality detecting device for front-rear acceleration sensor - Google Patents

Abstract

PURPOSE:To accurately detect the abnormality of the front-rear acceleration sensor and to minimize an influence upon a control system if the abnormality is not removed as it is by using the front-rear acceleration detected value in non-acceleration/ deceleration operation as the base of abnormality judging operation. CONSTITUTION:The front-rear acceleration sensor (a) outputs the front-rear acceleration detected value corresponding to the front-rear acceleration of a vehicle in the form of an electric signal. Further, an acceleration/deceleration operation detecting means (b) detects the acceleration/deceleration operation of the vehicle. Then while the acceleration/deceleration operation detecting means (b) detects the non-acceleration/ deceleration operation, a sensor abnormality detecting means (c) detects the front-rear acceleration sensor (a) being abnormal if the front-rear acceleration detected value from the front-rear acceleration sensor (a) indicating a value corresponding to the acceleration/deceleration operation of the vehicle continuously for a specific time. Then when the sensor abnormality detecting means (c) outputs a sensor abnormality signal, a fail-safe operation means (d) performs specific fail-safe operation, namely, generates a warning and carries out specific operation for stopping the system control, etc. Consequently, the abnormality of the sensor can accurately be detected.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is used as a sensor that provides longitudinal acceleration information in control systems such as anti-lock brake control devices, front and rear wheel drive force distribution control devices, and active suspension control devices. The present invention relates to a forward acceleration sensor abnormality detection device.

(Prior Art) Conventionally, as a forward acceleration output value correction device applied to an anti-lock brake control device, for example,
A device described in Japanese Patent No. 24166 is known.

This conventional source states that the longitudinal acceleration detected value obtained from the longitudinal acceleration sensor and the longitudinal acceleration calculated value obtained by differential calculation of the vehicle speed from the vehicle speed sensor are compared at low acceleration/deceleration, and the difference between the two values is determined by a predetermined value. A device is shown in which shift correction is performed to make the detected longitudinal acceleration value coincide with the computed longitudinal acceleration value in the above case, and the longitudinal acceleration correction value obtained by this correction processing is used as control information for the anti-lock brake control device.

(Problem to be Solved by the Invention) However, such a conventional longitudinal acceleration output value correction device is a device that assumes that the longitudinal acceleration sensor is normal. This is an effective device when the longitudinal acceleration detection value includes an inclination component and the longitudinal acceleration detection value is output with an offset error, but if the longitudinal acceleration detection value from the sensor always outputs a constant value, Furthermore, when a so-called frontal acceleration sensor is abnormal, such as outputting a detected value that fluctuates regardless of the longitudinal acceleration of the vehicle, it has a significant effect on a control system that uses the detected longitudinal acceleration value as control information.

For example, in an anti-lock brake control system, the vehicle speed is estimated by integrally calculating the detected longitudinal acceleration value, and the criteria for determining whether to increase, decrease, or maintain brake fluid pressure is determined based on this estimated vehicle speed and wheel speed. Since the slip ratio of each wheel is calculated as follows, the accuracy of the slip ratio is lost, and braking distance may be extended due to insufficient brake fluid pressure, or wheel lock may occur due to excessive brake fluid pressure.

Therefore, as a device for detecting abnormalities in longitudinal acceleration sensors, it is possible to install two or more longitudinal acceleration sensors and detect abnormalities by comparing the detection values from these sensors, but in this case, it is expensive. It becomes.

The present invention has been made by focusing on the above-mentioned problems, and uses a cost-effective device to accurately detect an abnormality in a longitudinal acceleration sensor applied to various control systems of a vehicle. The challenge is to minimize the impact on the control system caused by

(Means for Solving the Problems) In order to solve the above problems, the longitudinal acceleration sensor abnormality detection device of the present invention uses the longitudinal acceleration detected value during non-acceleration/deceleration operation as the basis for abnormality determination of the lateral acceleration sensor. The device was designed to detect

That is, as shown in the complaint correspondence diagram of FIG. 1, there is a longitudinal acceleration sensor a that outputs a detected longitudinal acceleration value according to the longitudinal acceleration of the vehicle as an electrical signal, and an acceleration/deceleration operation detection means that detects the acceleration/deceleration operation of the vehicle. When the acceleration/deceleration operation detection means detects that a non-acceleration/deceleration operation is being performed, the longitudinal acceleration detected value from the front acceleration sensor a outputs a value corresponding to the acceleration/deceleration of the vehicle. A sensor abnormality detection means C detects that the forward acceleration sensor a is abnormal if the state continues for a predetermined period of time, and when a sensor abnormality signal is output from the sensor abnormality detection means C, a predetermined fail-safe operation is performed. It is characterized by comprising a fail-safe activation means d.

(Function) When a sensor abnormality occurs, when the sensor abnormality detection means C detects that a non-acceleration/deceleration operation is being performed from the acceleration/deceleration operation detection means, the longitudinal acceleration detected from the longitudinal acceleration sensor a is A sensor abnormality signal is output when the abnormality determination condition that a value corresponding to acceleration/deceleration is output continues for a predetermined period of time is output, and the fail-safe activation means d issues a warning or performs a predetermined action such as stopping system control. Fail-safe operation is performed.

Therefore, an abnormality in the longitudinal acceleration sensor a applied to various vehicle control systems can be accurately detected with a cost-effective device that does not require the use of multiple sensors, and the abnormality can be detected easily.
It is possible to minimize the impact on the control system that would otherwise occur.

(First example) First, the configuration will be explained.

Figure 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 according to the embodiment is applied and a drive system to which a four-wheel drive vehicle torque split control system is applied. Yes, first of all,
The configuration of the torque spring/seat control system will be explained.

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. Transmission 2゜Transfer input shaft 3
．． Rear propeller shaft 4, rear differential 5
．． Rear wheel 6. Transfer output shaft7. Front propeller shaft 8, front differential 9. The front wheel 10 is equipped with a front wheel 10, to which the engine driving force that has passed through the transmission 2 is directly transmitted, and to the front wheel 10 is a transfer clutch provided between the transfer input and output shafts 3 and 7 of the front wheel drive system. transmitted via device 11.

The Torx-Bnot control system, which optimally controls the distribution of driving force between the front and rear wheels while achieving both driving performance and steering performance, uses the transfer clutch device 11 (for example, special request for
3-325379), a control oil pressure generator 20 that generates the control oil pressure Pc that becomes the clutch engagement force, and a solenoid valve 28 provided in the control oil pressure generator 20 from various human power sensors 30. A predetermined solenoid drive current engineer based on the information of. Torque split control section 40 of control unit C/U that outputs T5
and an alarm lamp 50 that lights up in the event of various abnormalities.

The hydraulic control device 20 includes a motor 22 that is driven or stopped by a relief switch 21, a hydraulic pump 24 that is operated by the motor 22 to suck water from a reservoir tank 23, and a pump discharge pressure (-next pressure) from the hydraulic pump 24. an accumulator 26 that stores oil via a check valve 25, and a solenoid that adjusts the line pressure (secondary pressure) from the accumulator 26 to a predetermined control oil pressure Pc using the solenoid drive current I, □5 from the torque sprint control unit 40. The hydraulic fluid of the control hydraulic pressure Pc is supplied to the clutch boat through a control hydraulic pressure pipe 29.

As shown in the block diagram of the system electronic control system in FIG. 3, the various input sensors 30 include a left front wheel rotation sensor 30a, a right front rotation sensor 30b, and a left rear wheel rotation sensor 3.
0c, right rear wheel rotation sensor 30d, accelerator opening sensor 3
0e, lateral acceleration sensor 30f, drive current sensor 309.
It has a control oil pressure sensor 30h and a front wheel axle torque sensor 30i.

As shown in the block diagram of the system electronic control system in FIG. 3, the torque split control section 40 includes a left front wheel speed calculation circuit 40a, a right front transport speed calculation circuit 40b, a left rear wheel speed calculation circuit 40c, and a right rear wheel speed calculation circuit 40a. Arithmetic circuit 40d, front wheel speed computing circuit 40
e, i Transportation speed calculation circuit 40f0 Rotational speed difference calculation circuit 4o9
．． Lateral acceleration output value correction circuit 40h, gain calculation circuit 40
i.

fastening force calculation circuit 40], dither signal generation circuit 40, solenoid drive circuit 4C12, rotational speed difference output value abnormality detection circuit 40m, lateral acceleration sensor abnormality detection circuit 40n, clutch abnormality detection circuit 40o, abnormality judgment threshold circuit 40p.
, has a fail-safe circuit 40q.

As shown in the block diagram of the system electronic control system in FIG. 3, the warning lamps 50 include a rotational speed difference abnormality warning lamp 50a, a lateral acceleration sensor abnormality warning lamp 50b, and a clutch abnormality warning lamp 5°C.

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

The braking system to which the four-wheel anti-lock brake control system of the embodiment is applied is, as shown in FIG. 2, a brake pedal 60. Booster 61. Master cylinder 62. Actuator 63. Wheel cylinders 64a, 64b, 64c,
64d, brake piping 65.66a, 66b, 66c,
It is equipped with 66d.

By controlling the braking force so that the slip ratio of each wheel, calculated from the vehicle speed and each wheel speed, converges to around 0.15 to 0.3, the wheels are locked during sudden braking or braking on low μ roads. The four-wheel anti-lock brake control system that prevents brake fluid pressure increases the brake fluid pressure based on the actuator 63 having a three-position switching solenoid valve and a hydraulic pump motor, and information from various input sensors 30 to the actuator 63. It is composed of an anti-lock brake control section 70 of a control unit C/U that outputs drive commands for pressure reduction and holding, and an alarm lamp 50 that lights up in the event of various abnormalities.

As shown in the block diagram of the system electronic control system in FIG. 3, the various input sensors 30 include a front acceleration sensor 30j and a stop lamp switch 30k, a left front wheel rotation sensor 30a that provides necessary information, and a right front wheel The rotation sensor 30b, the left rear wheel rotation sensor 30C2, the right rear wheel rotation sensor 30d, etc. are shared with the torque split control system.

As shown in the block diagram of the system electronic control system in FIG. 3, the anti-lock brake control section 70 includes a vehicle speed calculation circuit 70a, an anti-lock control circuit 70b, an actuator drive circuit 70c, and a longitudinal acceleration sensor abnormality detection circuit 7.
0d, and has a fail-safe circuit 70e.

The warning lamp 50 includes a frontal acceleration sensor abnormality warning lamp 50d.

Note that the longitudinal acceleration sensor abnormality detection device of the embodiment detects an abnormality in the longitudinal acceleration sensor 30j.
0j, the stop lamp switch 30, the longitudinal acceleration sensor abnormality detection circuit 70d, and the failsafe circuit 70.
e and an alarm lamp 50d.

Next, the effect will be explained.

FIG. 4 is a flowchart showing the flow of the brake fluid pressure control operation in the anti-lock brake control section 70, and the flow of the control operation will be explained in order of each step.

In step 80, the stop lamp switch 30k is turned OFF.
It is determined whether or not it is N, that is, whether or not it is a braking operation by depressing the brake pedal.

In step 81, it is determined whether or not the reciprocating longitudinal acceleration sensor 30j is normal based on the result of the abnormality detection process. If the longitudinal acceleration sensor 30j is abnormal, the process proceeds to step 82; if the longitudinal acceleration sensor 30j is normal, the process proceeds to step 82. If the predetermined anti-lock 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 anti-lock brake control is stopped and a lighting command is output to the warning lamp 50d.

Note that even if the anti-lock brake control is stopped, the brake fluid pressure from the mask cylinder 62 is applied to each wheel cylinder 64.
Normal brake operation is ensured for brakes a, 64b, 64c, and 64d.

In step 83, the left front wheel speed VWF and the right front wheel speed VWFR are
The left rear wheel speed VWRR, the right rear wheel speed VWRR, and the detected longitudinal acceleration value x 9 are read.

In step 84, the detected longitudinal acceleration value x 9 and the left front wheel speed V
The left front wheel slip rate SFL is calculated based on the following equation.

Ve=S IXc+ldt (Ve; estimated vehicle speed) In steps 85 and 86, the left front wheel slip rate SEL and the slip rate threshold S are determined. , Sl is compared in magnitude, and when S o < S FL < S + where the braking resistance coefficient (braking force) is the maximum, step 8
A brake fluid pressure holding command is output at step 7, and when the wheels tend to lock S FL 2 S +, a brake fluid pressure reduction command is output at step 88, resulting in insufficient braking force.
When FL≦80, a brake fluid pressure increase command is output in step 89.

Incidentally, the operations from step 84 to step 89 are similarly performed independently for each of the right front wheel, left rear wheel, and right rear wheel.

FIG. 5 is a flowchart showing the flow of the longitudinal acceleration sensor abnormality detection operation of the first embodiment, which is performed by interrupt processing at regular intervals (for example, every +0 m5ec) during the brake fluid pressure control operation. Explain the flow to each step.

In step 90, the longitudinal acceleration detection value x9 from the longitudinal acceleration sensor 30j and the switch signal (SSW) from the strike lamp switch 30k are read.

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

In step 92, the absolute value lX of the detected longitudinal acceleration value×9
91 is the sensor fail judgment threshold x90 (for example, 0
．． In step 3, it is determined whether or not l) is greater than or equal to l).

When the conditions of step 91 and step 92 are satisfied at the same time, that is, when the longitudinal acceleration detection value x 9 is a value corresponding to when the vehicle is decelerating even though the brake is not operated, there is a sensor abnormality. Assuming that the possibility is high, proceed to step 93, and set the timer value lower by T + 10 (m
sec).

On the other hand, if even one of the conditions in step 91 and step 92 is not satisfied, it is assumed that the sensor is normal, and the process proceeds to step 94, where the timer value T is set to 0.

In step 95, the timer value T is below the set timer value.

(For example, +00m5ec) It is determined whether or not it is above LLJ, and when T<T, the process proceeds to step 96, where it is determined that the longitudinal acceleration sensor 30j is normal.
Also, Ding≧Ding. When this happens, the process proceeds to step 97, and a determination result that the longitudinal acceleration sensor 30j is abnormal is output.

As explained above, the longitudinal acceleration detection value x 9 from the frontal acceleration sensor 30J always outputs a constant value, or the longitudinal acceleration detection value x 9 that fluctuates independently of the vehicle longitudinal acceleration, etc. When the sensor is abnormal, the detected longitudinal acceleration value x 9 continues to be a value corresponding to when the vehicle is decelerating even though the brake is not operated, so the process proceeds from step 81 to step 82, and the anti-lock brake is activated. A fail-safe operation is performed in which the control is stopped and the warning lamp 50d is turned on to notify the driver that the longitudinal acceleration sensor 30j is abnormal.Then, the sensor abnormality is dealt with by inspecting or replacing the longitudinal acceleration sensor 30j. I can do it.

Therefore, the forward acceleration sensor abnormality detection device of the first embodiment has the following features.

■ Non-deceleration operation detection, which is the basis for abnormality judgment, is based on the signal from the stop lamp switch 30k, which is pre-installed in the anti-lock brake control system. Accurate detection can be performed with a cost-effective device that does not use an acceleration sensor.

■ If the longitudinal acceleration sensor 30j is abnormal, the anti-lock brake control is immediately stopped and the warning lamp 50d is lit to notify the driver of the abnormality, so the anti-lock brake control that would occur if the abnormality were left as is. The impact on the system can be minimized.

For example, the vehicle speed vII, which is estimated by integrating the longitudinal acceleration detection value x 9, is the standard for determining the slip rate S of each wheel, so if this slip rate S is inaccurate, the brake fluid Insufficient brake fluid pressure may lengthen the braking distance, and excessive brake fluid pressure may cause wheel locking.

(Second Example) Next, a forward acceleration sensor abnormality detection device according to a second example will be described.

The device of the second embodiment is an example in which the device of the first embodiment detects an abnormality in the forward acceleration sensor by detecting a non-deceleration operation when the brake is not being operated, whereas This is an example of detecting an abnormality in the frontal acceleration sensor by detecting an operation.

The configuration of the device is the same as the device of the first embodiment, except for the addition of an accelerator pedal switch 30f2 shown in FIG. 3, so a description thereof will be omitted.

FIG. 6 is a flowchart showing the flow of the longitudinal acceleration sensor abnormality detection operation of the second embodiment, which is performed by interrupt processing at regular intervals (for example, every JOmsec), and the flow of the detection operation will be explained in order of each step.

In step 100, the longitudinal acceleration detected value x9 from the longitudinal acceleration sensor 30j and the accelerator pedal switch 30β are calculated.
The switch signal (ASW) from is read.

In step 101, a switch signal (ASW
) is OFF, that is, whether or not the accelerator is not operated.

In step 102, the absolute value l of the detected longitudinal acceleration value×9
X91 is the sensor fail judgment threshold x 9 (for example, 0.1
9) It will be judged whether it is above or not.

If the conditions of step 101 and step 102 are satisfied at the same time, that is, when the longitudinal acceleration detection value x 9 is a value corresponding to when the vehicle is accelerating even though the accelerator is not operated, the sensor is abnormal. Assuming that the possibility is high, proceed to step 103 and set the timer value T to T + 10.
(msec) is added.

On the other hand, if even one of the conditions in step 101 and step 102 is not satisfied, it is assumed that the sensor is normal, and the process proceeds to step 104, where the timer value T is set to O.

Incidentally, steps 105 to 107 correspond to steps 95 to 97 in the first embodiment, so their explanation will be omitted.

(Third Example) Next, a longitudinal acceleration sensor abnormality detection device according to a third example will be described.

Similarly to the second embodiment, this third embodiment is also an example in which an abnormality in the longitudinal acceleration sensor is detected by detecting a non-acceleration operation in which an accelerator operation that causes the vehicle to be accelerated is not performed.

Regarding the device configuration, the only difference is that an accelerator pedal switch 30I2 is used in the device of the second embodiment, whereas an accelerator opening sensor 30e is used as an acceleration operation detection means, and a detailed explanation will be omitted.

FIG. 7 is a flowchart showing the flow of the longitudinal acceleration sensor abnormality detection operation of the third embodiment, which is performed by interrupt processing at regular intervals (for example, every I0m5ec), and the flow of the detection operation will be explained in order of each step.

In step 110, the longitudinal acceleration detection value x 9 from the longitudinal acceleration sensor 30j and the accelerator opening detection value A from the accelerator opening sensor 30e are read.

In step 111, the accelerator opening detection value A from the accelerator opening sensor 30e serving as an acceleration operation detection means is set to a small value that is a threshold value for an acceleration operation and a non-acceleration operation. It is determined whether or not the condition is below, that is, whether it is a non-acceleration operation.

Incidentally, steps 112 to 117 correspond to steps 102 to 107 in the second embodiment, so their explanation will be omitted.

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

For example, in the example, an example of a longitudinal acceleration sensor abnormality detection device applied to an anti-lock brake control system was shown, but various in-vehicle control systems that use a longitudinal acceleration sensor as an input sensor, such as a torque split control system and an active suspension Of course, the present invention can also be applied to control systems, four-wheel steering control systems, and the like.

In addition, in the example, an example was shown in which the control system that is continuously used as a fail-safe operation is stopped and a warning lamp is turned on. It is also possible to combine one or more of various fail-safe operations, such as [transferring to a safe state].

In addition, in the embodiment, when detecting an abnormality in the longitudinal acceleration sensor, examples were shown during non-deceleration operation (first embodiment) and non-acceleration operation (second and third embodiments). An abnormality in the longitudinal acceleration sensor may be detected based on the fact that the vehicle is in a non-accelerating operation.

In addition, the acceleration/deceleration operation detection means may be any means that can detect acceleration/deceleration operations, and in addition to those mentioned in the embodiments, brake fluid pressure, engine intake pressure, etc. may also be used. .

(Effects of the Invention) As explained above, in the frontal acceleration sensor abnormality detection device of the present invention, abnormality of the lateral acceleration sensor is detected using the longitudinal acceleration detected value during non-acceleration/deceleration operation as the basis for abnormality judgment. This device accurately detects abnormalities in longitudinal acceleration sensors applied to various vehicle control systems with a cost-effective device, and minimizes the impact on the control system that would occur if abnormalities were left untreated. You can get the effect of being able to do a lot of things.

[Brief explanation of drawings]

FIG. 1 is a complaint correspondence diagram showing the longitudinal acceleration sensor abnormality detection device of the present invention, and FIG. 2 is an overall schematic diagram showing the drive system, braking system, and control system of a four-wheel drive vehicle to which the embodiment device is applied.
FIG. 3 is a block diagram showing the electronic control system to which the embodiment device is applied, FIG. 4 is a flowchart showing the flow of anti-lock brake control operation, and FIG. 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 flow of the frontal 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 activation means

Claims (1)

[Scope of Claims] 1) A longitudinal acceleration sensor that outputs a detected longitudinal acceleration value according to vehicle longitudinal acceleration as an electrical signal, an acceleration/deceleration operation detection means that detects an acceleration/deceleration operation of the vehicle, and the acceleration/deceleration operation detection means. When it is detected that a non-acceleration/deceleration operation is being performed from A sensor abnormality detection means for detecting that the sensor abnormality detection means is abnormal; and a failsafe activation means for performing a predetermined failsafe operation when a sensor abnormality signal is output from the sensor abnormality detection means. Longitudinal acceleration sensor abnormality detection device.