JPH0390864A - Abnormality detecting device for acceleration sensor on vehicle - Google Patents

Abstract

PURPOSE:To securely prevent an abnormal state from being misdetected by judging abnormality when a state wherein the difference value of a difference value arithmetic means has the same polarity and exceeds a set value continues for a specific time. CONSTITUTION:The sensor abnormality detecting device has two acceleration sensors which detect acceleration that the vehicle has in the same direction and the difference arithmetic means which calculates the difference between the acceleration detected values of both the acceleration sensors. Then an abnormality detecting means judges abnormality when the state wherein the difference of the difference arithmetic means has the same polarity and exceeds the set value continues for the specific time. The absolute value of the difference between the acceleration detected values of the two acceleration sensors is not compared with the set value and it is judged whether the difference between the acceleration detected values is plus or minus; when the state wherein the difference value exceeds the set value while still plus or minus continues for the specific time, it is judged that one acceleration sensor is abnormal, so the abnormality of the acceleration sensor is securely prevented from being misdetected.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an acceleration sensor abnormality detection device for a vehicle equipped with two acceleration sensors that detect acceleration in the same direction such as lateral acceleration and vertical acceleration occurring in the vehicle. .

[Conventional technology]

In recent years, vehicles have come to be equipped with electronic control devices such as active suspensions, anti-skid control devices, and drive force distribution control devices for front and rear wheels. Using an acceleration sensor that detects acceleration such as directional acceleration and vertical acceleration,
Various controls are performed based on the detected acceleration values output from these devices (Japanese Patent Laid-Open No. 63-145115, Japanese Patent Publication No. 51-6305, Japanese Patent Laid-open No. 61-169).
(See Publication No. 326, etc.).

In such an electronic control device, if a zero-output error occurs in which the output of the acceleration sensor becomes zero even though acceleration is occurring, control is performed with the acceleration set to zero, and the Although this is not a problem, in the case of an abnormality on the output generation side where a detected acceleration value that exceeds the actual acceleration is output, in the case of an active suspension,
There is a risk of increasing the roll of the vehicle, and in the anti-skid control system, the pseudo vehicle speed is calculated to be much lower than the actual vehicle speed, which may cause the wheels to lock.In the driving force distribution control system, the control gain is There is a risk that the vehicle may spin or drift as the vehicle shifts from a four-wheel drive state to a two-wheel drive state.

For this reason, conventionally, to detect abnormalities in acceleration sensors,
The maximum value of acceleration that can normally occur under the running condition of the vehicle is used as the reference value for judgment (for example, in the case of lateral acceleration, the acceleration at this time cannot exceed the turning limit acceleration of the vehicle), and this reference value for judgment is used. This value is compared with the detected acceleration value output from the acceleration sensor, and when the latter becomes larger than the former, it is determined that there is an abnormality on the output generation side of the acceleration sensor.

[Problem to be solved by the invention]

However, in the above-mentioned conventional acceleration sensor abnormality detection device, the maximum value of acceleration that can normally occur while the vehicle is running is used as a criterion for determining acceleration sensor abnormality, so the detected acceleration value of the acceleration sensor becomes abnormally high. However, if the detected acceleration value exceeds the allowable error, but the error is not very large, it is possible to detect an abnormality in the acceleration sensor until the vehicle running state approaches the maximum acceleration value. There was an unresolved issue that it could not be done.

In order to solve this unresolved problem, the present applicant has developed a method for distributing longitudinal driving force using the average value of two lateral acceleration sensors as the detected acceleration value, as previously described in Japanese Patent Application No. 1-118319. In a control device, an acceleration sensor abnormality detection circuit that calculates the absolute value of the difference between detected acceleration values and detects an abnormality in the acceleration sensor when the absolute value of the difference continues to be equal to or greater than a set value for a predetermined period of time. is proposed.

According to this acceleration sensor abnormality detection circuit, it is possible to detect an abnormality in the acceleration sensor when the absolute value of the difference value between the acceleration detection values of the two lateral acceleration sensors continues to be equal to or higher than the set value for a predetermined period of time. Although a sensor abnormality can be determined under normal driving conditions, the detected acceleration value of an acceleration sensor generally has a resonance frequency (for example, 38Hz).
When driving on a rough road where there is a resonance peak (for example, about +30 dB) at the resonance frequency, the detected acceleration value increases and a node is created between the two acceleration sensors. The difference between the acceleration detection values of the two acceleration sensors may become significantly large, and in this case, the above judgment criteria may be exceeded and the acceleration sensor may be mistakenly judged to be abnormal even though it is normal. A new issue arises.

Therefore, the present invention has been made by focusing on the above-mentioned problems of the conventional example, and is designed to ensure that an abnormal state is not detected incorrectly when determining an abnormality of an acceleration sensor based on the difference value between two acceleration sensors. It is an object of the present invention to provide an acceleration sensor abnormality detection device that can prevent such problems.

[Means to solve the problem]

In order to achieve the above object, an acceleration sensor abnormality detection device for a vehicle according to the present invention, as shown in the basic configuration diagram of FIG. A difference value calculation means for calculating the difference value between the acceleration detection values of both acceleration sensors, and the difference value between the difference value calculation means are within the same polarity and the state of exceeding the set value continues for a predetermined time, it is determined that there is an abnormality. The present invention is characterized by comprising an abnormality detection means for detecting an abnormality.

[Operation] In this invention, instead of comparing the absolute value of the difference between the acceleration detection values of the two acceleration sensors with a set value, the difference between the acceleration detection values of the two acceleration sensors is determined to be positive or negative. If the difference value is positive or negative and exceeds the set value for a predetermined period of time, it is determined that one of the acceleration sensors is abnormal. Even when the vehicle travels on a rough road that generates acceleration near the resonance frequency, an abnormality in the acceleration sensor is not erroneously detected, and accurate abnormality detection can be performed.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 2 is a hydraulic system diagram showing an embodiment in which the acceleration sensor abnormality detection device for a vehicle according to the present invention is applied to an active suspension.
Ii indicates front left to rear right wheels, 12 indicates 1 opt for each wheel,
The wheel side member connected to ~l0RR is shown, and 14 is the vehicle body side member. A hydraulic active suspension 16 is provided between each wheel side member 12 and the vehicle body side member 14.

The active suspension 16 includes a hydraulic pressure supply device 18 as a fluid pressure supply device, a pressure holding section 20 and a fail-safe valve 22 interposed on the load side of the hydraulic pressure supply device 18, and a fail-safe valve 22 on the load side of the fail-safe valve 22. Accumulators 24 and 24 are installed corresponding to the front and rear wheels, and the wheel 1
Pressure control valve 26 equipped corresponding to 0FL~l0RR
It includes FL to 26RR and hydraulic cylinders (fluid cylinders) 28FL to 28RR which are loads. The active suspension system 16 also includes two lateral acceleration sensors 30A and 30B as acceleration detection means, one longitudinal acceleration sensor 31, and other wheels 10F except for the front left wheel 10FL.
Vehicle body side member 14 located near R, l0RL and l0RR
Vertical acceleration sensors 32FR to 32RR arranged in
The acceleration detection values of these lateral acceleration sensors 30A, 30B, longitudinal acceleration sensor 31, and vertical acceleration sensors 32FR to 32RR are YGA+YG1% XG and Z Fl""
Each pressure control valve 26PL~261' based on Z 1111
The lateral acceleration sensor 30A calculates pressure command values PFL to P□ for lR.

When an abnormality in 30B is detected, the fail-safe valve 2
2, and a control device 34 for switching control. In addition,
35 is a coil spring that supports the static load of the vehicle body.

The hydraulic supply device 18 includes a reservoir tank 40 that stores hydraulic oil, and a hydraulic pump 4 that uses an engine as a rotational drive source.
2 and a relief valve 44 that sets a predetermined line pressure, that is, a supply side pipe (supply line) 48S that supplies hydraulic oil to the tank 40 and a return side pipe (return line) that returns hydraulic oil. 48r, and the supply side conduit 48s reaches the next stage pressure holding section 20 via the hydraulic pump 42. Further, a relief valve 44 is connected between the pipes 48s and 48r at a position on the discharge side.

The pressure holding unit 20 includes a check valve 50 inserted into the supply pipe line 48s, and an operating check valve 52 inserted into the return pipe line 48r, which uses the load side pressure of the fail-safe valve 22 as the pilot pressure Pt. have The operating check valve 52 opens the valve to release the check when the pilot pressure P exceeds a set value (in this case, the operating neutral pressure PN: see Fig. 3), and opens the valve when the pilot pressure P is below the neutral pressure PN. It has a pilot-operated check valve structure that closes and checks.

Also, the return side pipe 4 upstream of the operating check valve 52
A diaphragm 54 is inserted in 8r, and this diaphragm 54
A bypass path 48B is provided to bypass the.

The fail-safe valve 22 connects the pump boat P and the boat A to the supply line 48s at a position downstream of the check valve 50, and connects the tank boat T and the boat B to the bypass line 48B. 2-position solenoid switching valve. When the control signal C5 given to the electromagnetic solenoid 22 is in the OFF state, the connection between the pump boat P and the boat A and between the boat B and the tank boat T is cut off, and the connection between the boats A and B is cut off. On the other hand, if switching signal C3 is on, pump boat P and boat A
and between boat B and tank boat T, respectively.

Therefore, when the engine is not rotating, the discharge pressure of the hydraulic pump 42 is also zero, and the operating check valve 5
2 is closed, the hydraulic control system including the pressure control valves 26FL to 26RR and the hydraulic cylinders 28FL to 28RR becomes a closed circuit and is sealed at the neutral pressure P0 by the operating check valve 52 and the check valve 50. Also, if the suspension is in a normal control state and the fail-safe valve 22
As will be described later, the supply side conduit 48s and the return side conduit 48
If r are communicated individually, the discharge pressure that increases as the engine rotates is the operating neutral pressure P.

The operating check valve 52 opens when the
Line pressure determined by relief valve 44 is supplied to the hydraulic control system.

Supply side pipe line 48s downstream of the fail-safe valve 22
The front wheel is 10FL, I OPR, and the rear wheel is 10RL.

It is branched corresponding to 10RR. After each pipe line 48s is connected to the relatively large capacity accumulator 24, it further branches corresponding to the left and right wheels, and is connected to the pressure control valve 26.
This leads to a supply boat from FL to 26RR, which will be described later. Further, the return boats of the pressure control valves 26FL to 26RR, which will be described later, merge at the left and right wheels, then merge at the front and rear wheels, and reach the operating check valve 52, as shown in the figure.

On the other hand, each of the pressure control valves 26FL to 26RR includes an input boat 261, a return boat 260, and a control pressure boat 26c.
It also has a control pressure boat 26c and an input boat 26.
A spool is provided at both ends of the spool for switching the communication state between the input boat 261 and the return boat 260 or the control pressure boat 26C and either the input boat 261 or the return boat 260. The pressure is supplied as a pilot pressure, and the supplied overwhelming pilot pressure is further controlled by a poppet valve controlled by a proportional solenoid 26s, so that the pressure of the control pressure boat 26C is always supplied to the proportional solenoid 26s from the control device 34. The pressure is controlled in accordance with the excitation electric current 'alFL~l1ljl.

Here, the relationship between the exciting current IFL~■□ and the control oil pressure Pc output from the control boat 26C is as shown in Fig. 3, when the command value IFL~111111 is near zero, P□8 is output. From this state, the command value IFL~III
As I increases in the positive direction, this increases by 1 for a given proportional gain.
Then, the control oil pressure PC increases and becomes saturated at the set line pressure PM of the pressure holding section 20.

Furthermore, each of the hydraulic cylinders 28FL to 28RR has a first
As shown in the figure, the piston 2 has a cylinder tube 28a, and the cylinder tube 28a has a through hole.
Upper and lower pressure chambers are defined by 8c, and thrust is generated by the difference in pressure receiving area with respect to the piston 28c. The lower end of the cylinder tube 28a is attached to the wheel side member 12, and the upper end of the piston rod 28b is attached to the vehicle body side member 12.
is attached to. In addition, each hydraulic cylinder 28FL
The pressure chamber of ~28 RR is connected via a throttle valve 36 to a small-capacity accumulator 37 for absorbing hydraulic vibrations in an unsprung resonance range (for example, 5 to 10 Hz).

Further, the lateral acceleration sensors 30A and 30B are arranged at a predetermined interval on a longitudinal axis passing through the center of gravity of a floor panel (not shown) of the vehicle, with the lateral acceleration sensor 30A located at the front. , lateral acceleration detection value Y, which becomes a positive neutral voltage 8 when the lateral acceleration is zero. When a leftward lateral acceleration occurs due to a rightward turn of the vehicle, the lateral acceleration detection value YG, which is a positive voltage lower than the proportional lateral acceleration detected value Yao, is expressed as a rightward lateral acceleration due to a leftward turn of the vehicle. When lateral acceleration occurs, lateral acceleration detection (1r Y a) proportional to the lateral acceleration is output. A lateral acceleration detection value Yc, which is a higher positive voltage, is output.Similarly, the longitudinal acceleration sensor 3
1 is also a longitudinal acceleration detected value X, which becomes a positive neutral voltage V when the longitudinal acceleration is zero. When there is a backward acceleration due to vehicle acceleration, the longitudinal acceleration detection value Y, which is a positive voltage lower than the longitudinal acceleration detection value YGo proportional to this, is the longitudinal acceleration detection value Y, which is a positive voltage lower than the longitudinal acceleration detection value YGo, which is proportional to the rearward acceleration due to the acceleration of the vehicle. When this occurs, the longitudinal acceleration detected value YG (1
The detected longitudinal acceleration values Ye, which are higher positive voltages, are respectively output. Furthermore, vertical acceleration sensors 32FR to 30RR
Also, the positive neutral voltage V when the vertical acceleration is zero. The vertical acceleration detected value Z is proportional to the vertical acceleration detected value Z GO when downward acceleration occurs in the vehicle.

. Outputs a vertical acceleration detection value ZG that is a lower positive voltage, and outputs a vertical acceleration detection value ZG that is a higher positive voltage than a proportional vertical acceleration detection value Zo when upward acceleration occurs in the vehicle. do.

Furthermore, as shown in FIG. 4, the control device 34 includes a power supply circuit 60, a microcomputer 61, and each control valve 26FL output from the microcomputer 61.
Solenoid drive circuits 62FL to 62RR to which pressure command values PFL””pHll for ~26RR are individually supplied
It is equipped with

The power supply circuit 60 includes an ignition relay 64 whose one end is connected to a battery 63, and two switching transistors Q whose collectors are connected to the other end of a relay coil 64a whose one end is connected to the battery 63.

and Q2, and the other end of the ignition relay 64 supplies power to each part of the control device 34.
4a, and transistor Q.

The base of the transistor Q2 is connected to the battery 63 via the ignition switch 65, the self-holding signal SS from the interface circuit 61a of the microcomputer 61 is supplied to the base of the transistor Q2, and the emitter of each transistor Q is grounded. There is.

The microcomputer 61 has at least an interface circuit 61a, a microprocessor 61b, and a storage device 61c, and the interface circuit 61a has lateral acceleration detection values Y c a + Y c * of the lateral acceleration sensors 30A and 30B on its input side. The longitudinal acceleration detection value X of the longitudinal acceleration sensor 31 and the vertical acceleration sensor 32FR~
The vertical acceleration detection values ZGFII-ZG□ of 32RR are respectively A/D converters 65A.

65B, 66, and 67FR to 67RR, and the pressure command values PFL to P□ output from the output side are D/
It is converted into an analog voltage by the A converters 68FL to 68RR, and is supplied to the solenoid drive circuits 62FL to 62RR, and a self-holding signal SS is supplied to the base of the transistor Q of the power supply circuit 60.

The microprocessor 61b calculates the vehicle rear wheel side roll suppression pressure command value PRu based on the acceleration detection value YGA of the acceleration sensor 30A, and also calculates the rear wheel roll suppression pressure command value PRu of the acceleration sensor 30B.
Acceleration detection value Y. The front wheel roll suppression pressure command value PR is calculated based on the front wheel side roll suppression pressure command value PR, and the pitch suppression pressure command value P for suppressing the pitch of the vehicle is calculated based on the acceleration detection of the longitudinal acceleration sensor 31 (IIXG). Vertical acceleration detection value ZGFII of 32FR to 32RR
− Vertical acceleration ZG of the remaining front left wheel position based on ZG□
FL is calculated, and each vertical acceleration detection value ZGFL -Za*
Bounce suppression pressure command value P B FL - P B ++ that suppresses the vertical movement of the vehicle, that is, bounce, based on
m is calculated, and these pressure command values are added and subtracted to calculate a pressure command value Prt""P□ that suppresses changes in the posture of the vehicle body, and these pressure command values PFL-P□ are sent to D/ Posture change suppression control is performed to output to the A converters 68FL to 68RR, and the lateral acceleration sensor 30
Acceleration detection values YGA and Y of A and 30B. Performs abnormality detection processing to determine whether both are normal or abnormal based on the
When an abnormality in the lateral acceleration sensors 30A and 30B is detected, the fail-safe valve 22 turns off the control signal C3.
At the same time, abnormal state processing is executed in which the self-holding signal SS is turned off. Further, a watchdog timer 69 for detecting program runaway is connected to the microprocessor 61b, and an abnormal state detection signal WS from the watchdog timer 69 is transmitted to the microprocessor 61b, for example.
(Non-maskable interlaced) The above-mentioned abnormal state processing is also executed when the signal is input to the terminal.

The storage device 61c is composed of a ROM, a RAM, etc., and stores in advance a program necessary for the arithmetic processing of the arithmetic processing device 61b, and sequentially stores the arithmetic results of the arithmetic processing device 61b.

Each of the solenoid drive circuits 62FL to 62RR is configured, for example, by a floating type constant current circuit, and supplies excitation currents IFL to ■□ to each of the pressure control valves 26FL to 26R according to the input pressure command voltages VFL to Vllll+.
Supplied to R proportional solenoid 26s.

Next, the operation of the above embodiment will be explained with reference to the flowcharts of FIGS. 5 and 6 showing the processing procedure of the microprocessor 61b.

When the ignition switch 65 is turned on, the transistor Q of the power supply circuit 60 is turned on, and in response, the ignition relay 64 is turned on, power is applied to the control device 34, and the microprocessor 61b is turned on. Posture change suppression processing shown in FIG. 5 is executed.

That is, first, in step 1, the control signal C3 is turned on, the fail-safe valve 22 is opened, and the self-holding signal SS is turned on, and then the process proceeds to step 2, where pressure commands are issued to each pressure control valve 26FL to 26RR. The value PFL-P□ is set as the initial command value P1. corresponding to the set pressure PM in the pressure holding section 20. ' to PIII' are set and output.

Next, proceed to step (3), and each acceleration sensor 30A
, 30B, 31, and 32FL to 32RR, the detected acceleration values Y, A, Y, .

In this step ■, each acceleration detection value Yca, YG
From lsXG and ZGFII-ZGIIN, the acceleration detected value Y is zero. , XGO and Z. Actual acceleration detection value YIA, Y1 that actually occurs in the vehicle by subtracting
1!1, XR and 2□9~Ze□ are calculated.

Next, proceed to step ■, and obtain the actual vertical acceleration detection value Z.
Based on IIFR-Z ***, the following equation (1) is calculated to calculate the estimated actual vertical acceleration ZIIFL at the front left wheel 10FL position.

Z IFL = Z IFI + Z□L ZIIF
II+・・・・・・・・・・・・(1) Next, proceed to step ■ and calculate each actual vertical acceleration detection value Z IIFII
~ZR,lR and the actual vertical acceleration estimated value ZjlFL are integrally calculated to calculate the vertical speed VZFL~■z,III of the vehicle body.

Next, proceed to step ①, and the vertical speed V 2FL~
A bounce suppression pressure command value P IIFL ~ P, □ is calculated by multiplying the vertical control gain set in advance by 2 for vz■, and this is updated and stored in the bounce suppression pressure command value storage area of the storage device 61c. Shift to step ■.

In this step (2), the rear wheel is set in advance to the actual lateral acceleration detected value YIA corresponding to the actual lateral acceleration, where the lateral acceleration calculated in the step (2) is positive when turning left, and the lateral acceleration when turning right is negative. The rear wheel side roll suppression pressure command value PRR is calculated by multiplying the side lateral direction control gain by □, and this is updated and stored in the rear wheel side roll suppression pressure command value storage area of the storage device 61c, and then the process proceeds to step (2). Transition.

In this step (2), an actual lateral acceleration detection value Y corresponding to the actual lateral acceleration is calculated, with the lateral acceleration calculated in the step (2) being positive when turning to the left and being negative when turning to the right. A front wheel side roll suppression pressure command value PRF is calculated by multiplying by a preset front wheel side lateral control gain KYF, and this is updated and stored in the front wheel side roll suppression pressure command value storage area of the storage device 61c, and then step Move to [phase].

In this step [phase], the actual longitudinal acceleration corresponding to the actual longitudinal acceleration with positive acceleration and negative deceleration during forward movement calculated in step (2) is detected (the longitudinal direction control gain preset in l!X□). The pitch suppression pressure command value PP is calculated by multiplying by KX, and this is updated and stored in the pitch suppression pressure command value storage area of the storage device 61c, and then the process moves to step (2).

In this step (2), each pressure command value PZFL-PZ stored in the bounce suppression pressure command value storage area, the front wheel and rear wheel roll suppression pressure command value storage area, and the pitch suppression pressure command value storage area of the storage device 61c, ,,PR□
PR, I and PP are successively prepared, and based on these, the following (2
) to (5) and calculate each pressure control valve 26FL to 2.
Calculate the pressure command value PFL""Pill for 6RR.

PFL=PM +PZFL PRF +PP ・Old・・・・・・(2)P□”PM10PZ□+PR,+PP
・・・・・・・・・(3) PIL-PM + PZ
*t P R * P P “”” (4) pHl
l÷PH0PZ*lI+PR, 1-PP (old) (5) However, PM is the set pressure of the operating check valve 52 of the pressure holding section 2o.

Next, the process moves to step @, where the pressure command value PFL''''PIIK calculated in step (2) is output, and then the process moves to step (2).

In this step @, it is determined whether or not the ignition switch 65 is in the off state, and when the ignition switch 65 is in the on state, the process returns to step (2), and when the ignition switch 65 is in the off state, step [phase] to move to.

In this step 0, it is determined whether a predetermined time sufficient for the preset operating check valve 52 of the pressure holding section 20 to be fully closed has elapsed, and if the predetermined time has not elapsed, step Shift to each pressure control valve 2
Pressure command value Pj for 6FL to 26RR (j=F
L, FR, RL.

RR) is within the permissible range obtained by adding or subtracting the permissible value α to the neutral pressure PM. If PH−α≦Pj≦Ps+α, the process returns to step [phase] and P, <P
When M−α or Pt>Ps+α, step ■
to move to.

In this step ■, it is determined whether each pressure command value Pj exceeds the neutral pressure P, and if PJ>PM, the process moves to step @ and the current pressure command value Pj is adjusted to a predetermined value, that is, a large vehicle pressure. A new pressure command value Pj is calculated by subtracting a value ΔP that does not cause a high change, and this is updated and stored. After outputting it to the pressure control valve 26j, the process returns to step [phase], and P, <P , then the step [stock]
, a predetermined value ΔP is added to the current pressure command value Pj to calculate a new pressure command value PJ, which is updated and stored, and is output to the pressure control valve 26j before returning to step 0.

On the other hand, when it is determined that the predetermined time has elapsed in step [phase], the process moves to step [phase] and the self-holding signal S
S is turned off, transistor Q2 of the power supply circuit 60 is turned off, the power supply to the control device 34 is cut off, and the process ends.

Further, the microprocessor 6ib also operates for a predetermined period of time, for example, 2 times.
The lateral acceleration sensor abnormality detection process shown in FIG. 6 is executed as a timer interrupt process every m5ec.

That is, in step 0, the lateral acceleration sensor 30A.

The lateral acceleration detection values YGA and YGI of 30B are read, and then the process moves to step @, where the lateral acceleration detection values Y and lateral acceleration detection values Y are obtained from A. Divide the value obtained by subtracting by 2 to get the difference value ΔY
After calculating I (-(YGA Yes)/2), the process moves to step 0.

In this step @, the difference value Δ calculated in step O
It is determined whether Y+ is greater than or equal to a preset allowable value ΔY (for example, equivalent to 0.3 G), and if ΔY1≧ΔY, the process moves to step [phase] and clears the abnormal time measurement timer Tt. Then, the process moves to step @, increments the abnormal time measurement timer T, and then moves to step [phase].

In this step [phase], it is determined whether the count value N of the abnormal time measurement timer T1 is equal to a preset value N3, and if Nt<Ns, the timer interrupt process is ended and the fifth Return to the processing in the figure, N + = N
s, the process moves to step O, where the abnormal time measurement timer TI is cleared, and then the process moves to step [phase], where the control signal C3 is turned off and the fail-safe valve 22 is turned off.
is set to a closed state, and then the process proceeds to step 0, where the self-holding signal SS is set to an OFF state, and the process ends.

On the other hand, when the determination result in step @ is ΔY, <ΔY, the process moves to step [phase] and the detected lateral acceleration value Y is determined.

The value obtained by subtracting the detected lateral acceleration value YGA from is divided by 2 to calculate the difference value ΔY2, and then the process moves to step [phase].

In this step [phase], it is determined whether the difference value ΔY2 calculated in the step [phase] is greater than or equal to the preset allowable value ΔY, and when ΔY2≧ΔY, the process moves to step @ and the error is detected. The time measuring timer T1 is cleared, and then the process moves to step 0, where the abnormal time measuring timer T□ is incremented, and then the process moves to step [phase].

In this step [phase], the count value N! of the abnormal time measurement timer T2! is equal to the set value N, and if Nt <Ns, the timer interrupt process is ended and the process returns to the process of FIG. 5, and if Nz""Ns, step @ The abnormal time measurement timer Tt
After clearing , proceed to the step [phase].

Furthermore, when the determination result of step [phase] is ΔYt<ΔY, the process moves to step [phase], clears the abnormal time measurement timers T+ and T, and then ends the timer interrupt processing, as shown in FIG. Return to processing.

In the process shown in FIG. 5, steps ■, 0 and [phase]
The processing of steps 0 to 0 corresponds to the difference value calculation means, and the processing of steps 0 to 0 corresponds to the abnormality detection means.

Therefore, when the vehicle is currently on a flat road surface with the ignition switch 65 turned off and the engine stopped, the hydraulic pump 42 is stopped, so the working pressure output from the fluid pressure supply device 18 is It has become zero,
The operating check valve 52 of the pressure holding section 20 is closed, and the hydraulic control system on the pressure control valves 26FL to 26RR becomes a closed circuit, and the pressure is transferred to the operating check valve 52.
The set pressure PM is maintained at the set pressure PM or a value slightly lower than this.

In this state, by turning on the ibunirasilane switch 65, power is supplied to the control device 34, the engine is started, and the daily working oil pressure of the fluid pressure supply device is increased.

At this time, the microprocessor 61b of the control device 34 starts the attitude change suppression process shown in FIG.
Pressure command values P□ to P□ for 6FL to 26RR are set to initial pressure command values PFL' to P□' corresponding to neutral pressure PH, and these are sent to the solenoid drive circuit via A/D converters 68FL to 68RR. 62FL to 62RR, and the control pressure P of each pressure control valve 26FL to 26RR is a neutral pressure P.

By controlling the fail-safe valve 22 to open, the fluid pressure supply bag! '1B
Hydraulic pressure from is supplied to the pressure holding section 20.

However, until the working pressure of the pressure supply device 18 reaches the holding pressure PH of the pressure holding part 20, the pressure holding part 2
0 maintains the pressure holding state, and the initial pressure command value PFL'
~PR11' is output, and in response, the excitation current IFL~fal is output from the solenoid drive circuits 62FL~62RR.
Even if l is output, the input boat 2611 of the pressure control valves 26FL to 26RR, the return port 26o, and the control pressure boat 2
Since the pressures 6c are the same, control using the excitation current IFL~■□ cannot be performed.

During this time, the microprocessor 61b repeats the control from step ① to step @ in FIG. At this time,
Since the vehicle is stopped, the vertical acceleration sensor 32FL~
The vertical acceleration detection value ZGFL"'ZG□ of 32RR becomes the neutral value 2.., and the lateral acceleration sensor 30A, 30B
The detected lateral acceleration value YGA+ YGI and the detected longitudinal acceleration value XG of the longitudinal acceleration sensor 31 are also neutral values Y0° and Xa.
. It becomes.

Therefore, the actual acceleration detection values ZIFL -Zt*m, 'l'lA, Yas, and x in the process of step (2). is zero, so the pressure command value PFL for each pressure control valve 26FL to 26RR calculated in step
pHll becomes neutral pressure PM, and initial pressure command value PFL~
P 1111' remains equal.

After that, the working pressure of the fluid pressure supply device 18 is applied to the pressure holding part 2.
When the holding pressure PM exceeds 0, the pressure oil is supplied into the closed circuit via the check valve 50.
When the pressure in the closed circuit increases and becomes equal to or higher than the set pressure Ps of the operating check valve 52, the operating check valve 52 becomes fully open and the pressure holding state is released. Therefore, the pressure of the hydraulic cylinders 28FL to 28RR can be controlled by the pressure control valves 26FL to 26RR, and the solenoid drive circuit 62F is based on the pressure command value Pyt=P□ output from the microprocessor 61b at this time.
Excitation current I FL"' I output from L~62RR
The control pressure Pc corresponding to 1111 is the hydraulic cylinder 28
Supplied to FL~28RR.

After that, when the vehicle is put into running mode, posture changes such as roll, pitch, and bounce are suppressed according to the longitudinal, lateral, and vertical accelerations that actually occur in the vehicle due to acceleration, deceleration, turning, vibration input from the road surface, etc. Control is started and the vehicle body can be maintained in a flat state. Note that the lateral acceleration detection value YtiA of the lateral acceleration sensor 30A placed at the front of the vehicle is used as the lateral acceleration detection value for rear wheel control, and the lateral acceleration detection value YtiA of the lateral acceleration sensor 30A disposed at the front of the vehicle is used as the lateral acceleration detection value for front wheel control.
By using the lateral acceleration detection values Y and A of the lateral acceleration sensor 30B located behind A, it is possible to improve the turning characteristics by setting the vehicle steering characteristics in the oversteer direction when looking back when the vehicle starts turning. , it is possible to improve driving stability by changing the vehicle steering characteristics to an understeer direction when converging at the end of a turn.

On the other hand, the microprocessor 61b executes abnormality detection processing for the lateral acceleration sensors 30A and 30B shown in FIG. In this case, both the detected lateral acceleration values YGA and YGm are the neutral value Y. As a result, the difference value ΔYl calculated in step @ also becomes zero, and the transition occurs from step [phase] to step [phase]. Since the difference value ΔYz calculated in this step [phase] is also zero, step The abnormal time measurement timer T moves from 0 to step [phase].

and T! is cleared and the process returns to the process shown in FIG. 5, the fail-safe valve 22 continues to be in the open state, and the normal attitude change suppression process shown in FIG. 5 continues.

In this straight running state, as shown in FIG. 7(a), at a certain point, for example, the lateral acceleration detected value Y
, A occurs on the output side, and when the difference value ΔY1 becomes the allowable value 67 or more at time Lt, at time t, when the timer interrupt in FIG. Move to [phase] and clear the second abnormal time measurement timer T2, then move to step @, increment the first abnormal time measurement timer TI, set the count value Nl to "1', and move to step @. In this case, N+<Ns
Therefore, the timer interrupt is terminated and the process returns to the process shown in FIG. Thereafter, each time the timer interrupt process is executed, the first abnormal time measurement timer T is incremented at time t.
When the count value N of the first abnormal time measurement timer T1 reaches the set value N in step 4, the process moves from step [phase] to step [phase] and clears the first abnormal time measurement timer T, Next, the process moves to step [phase], where the control signal C3 is turned off, and then the process moves to step @, where the self-holding signal ss is turned off, and the processing by the microprocessor 61b ends.

In this way, when the control signal C3 is turned off, the fail-safe valve 22 is closed, and the pressure control valves 26FL to 26FL are turned off.
The supply of hydraulic pressure from the fluid pressure supply device 18 to the pressure control valves 26RR is cut off, and the input ports 26i of the pressure control valves 26FL to 26RR are communicated with the operating check valve 52 via the throttle 54. As a result, the pilot pressure PP of the operating check valve 52 also decreases, and when this reaches the neutral pressure PP, the operating check valve 52 becomes fully closed, and the hydraulic control system on the pressure control valves 26FL to 26RR becomes a closed circuit. The pressure in the circuit is maintained at neutral pressure PM.

In this state, the pressure in the closed circuit is maintained at neutral pressure PM, and the pressure in the hydraulic cylinders 28FL to 28RR also becomes neutral pressure PM, making it possible to maintain the vehicle weight at the standard loading level at the target vehicle height. . At this time, the hydraulic cylinder 28FL
When vibration in the high frequency range of unsprung vibration is input to ~28RH from the wheel side, this vibration input can be absorbed by the throttle valve 36 and the Akiemulator 37, and relatively large vibration input due to unevenness of the road surface can be input. When the hydraulic cylinders 28FL to 28RR are
The increase in pressure can be absorbed by the accumulator 24 through the control pressure boat 26c and return boat 260 of the pressure control valves 26FL to 26RR and the failsafe valve 22, and as a result, the same function as a normal passive suspension is exhibited. can do. Further, when a program runaway occurs in the microprocessor 61b, this is detected by the watchdog timer 69, so that abnormal state processing similar to the above is executed.

In addition, when the vehicle is in a turning state and both acceleration sensors 30A and 30B are in a normal state, yaw angular acceleration is generated in the vehicle when looking back at the initial stage of the turn, and the front lateral acceleration sensor 30A is Lateral acceleration detection value YG
A is the lateral acceleration detection value Y of the rear side lateral acceleration sensor 30B
. However, the difference value ΔYI and Δ
Yt never becomes larger than the allowable value 67, and the process goes through steps @, @, ■ to [phase] and returns to the process shown in Fig. 5, and the difference value ΔYI (or ΔY2) becomes the allowable value 67 or more, the transition is made from step @ (or step [phase]) to step [phase] ~ @ (or step @ ~ @l), and the abnormal time measurement timer T
+ (or T count value N1 (or Nt) is incremented, but abnormal time measurement timer T+ (or T2)
count value N.

(or N,) is never equal to the set value N, and the attitude change suppression process shown in FIG. 5 continues.

In this turning state, if a zero-output error occurs in either of the lateral acceleration sensors 30A and 30B, the difference value ΔY or ΔY2 becomes the allowable value, similar to the sensor error during straight-ahead driving described above. 67 or more, the count value N or N2 of the first abnormal time measuring timer T or the second abnormal time measuring timer Tt reaches the set value N, and the above-mentioned fail-safe operation is performed.

Furthermore, when the vehicle is traveling on a rough road that generates a lateral acceleration component with a frequency corresponding to the resonance frequency (for example, 387) of the lateral acceleration sensors 30A and 30B, the detected values YGA and YGll of the lateral acceleration sensors 30A and 30B is the 8th
As shown in Figure (a), the value becomes larger than the actual lateral acceleration component, and a node is formed in the middle between both sensors 30A and 30B, so that the acceleration detection values YGA and YG of both acceleration sensors 30A and 30B become the As shown in FIG. 8(a), a phase difference close to 180 degrees may occur. At this time, the difference value ΔY+ calculated in step @ has a sine wave shape including a portion where the tolerance value is 67 or more, as shown in FIG. 8(b), and the difference value ΔY+ calculated in step [phase]
Y2 is a waveform obtained by vertically inverting the waveform (not shown in FIG. 8).

Therefore, in FIG. 8, between time points L0 and L, the difference values ΔYl and ΔY! are both smaller than the allowable value ΔY, so when the timer interrupt processing in Figure 6 is executed, the process moves to step [phase] through steps ~ @, @, [phase], and the abnormal time measurement timers TI and T2 are set. Since the count values N1 and N! of these timers T1 and T2 are cleared. are zero as shown in FIGS. 8(C) and 8(A), respectively.

Thereafter, when the timer interrupt process in FIG. 6 is executed at time t and later time 11, at this time tz, since ΔY1≧ΔY, the transition is made from step 0 to step [phase] and the second The abnormal time measurement timer Tt is cleared, and then the first abnormal time measurement timer T is cleared.

By incrementing , the count value N1 of timer T becomes 1'', and then the process moves to step @ and N
Since t <Ns, the timer interrupt processing is finished and the fifth
Return to the processing in the diagram.

Thereafter, each time the timer interrupt processing is repeated, the count value N of the abnormal time measurement timer TI is sequentially set to 1.

is incremented and the timer interrupt process is executed at time Ls, ΔY+<ΔY, so the process moves from step @ to step 0 via step [phase], and at this time t, the difference value ΔY2 becomes the allowable value. Since it is less than ΔY, the process moves to step [phase] and both timers T1 and Tt are cleared.

After that, at time t4, the first abnormal time measurement timer T,
starts incrementing at time t.

At time t after incrementing, ΔYI becomes ΔY, so the transition starts from step 0 through step [phase] to step [phase], and at this time t, the difference value ΔY! is the allowable value 6
7 or more, the process moves to step @ and clears the first abnormal time measurement timer Tl, then proceeds to step 0 to start incrementing the second abnormal time measurement timer Tz, and reaches time t.

Since ΔY is less than ΔY, the process moves to step [phase] and both timers T1 and T2 are cleared.

In this way, according to the above embodiment, the lateral acceleration sensor 3O
It is individually determined whether the two difference values ΔY between the detected lateral acceleration values YGA and Yag of A and 30B and the positive value of ΔY2 exceed the allowable value ΔY, and as a result, for example, the difference value This means that ΔYI is determined individually for both when the value is positive and when it is negative, and as between time t and 14 in FIG. 8, ΔY1
When the state of ≧ΔY suddenly changes to the state of ΔY2≧ΔY, it is not determined that the lateral acceleration sensors 30A and 30B are abnormal, and erroneous determination can be reliably prevented.

Incidentally, as in the conventional example, the lateral acceleration sensors 30A and 3
Detected lateral acceleration values Y, A, and Y of 0B. The absolute value of the difference value I
When determining an abnormality by comparing YGA YGII and set value ΔY, as shown in FIG. 8(e), time t,
Since the count value Ns of the abnormal time measurement timer continues to be incremented without being cleared between and 14, the count value N of the abnormal time measurement timer reaches the set value N at time t, At time t, /, it is erroneously determined that one of the lateral acceleration sensors 3OA and 30B is abnormal, and as a result, the fail-safe valve 22
is in the closed state and shifts to a pressure holding state by the pressure holding section 20, resulting in a fail-safe state, resulting in an unnecessary fail-safe operation.

Further, when the vehicle is stopped from a running state and the ignition switch 65 is turned off in this stopped state, the hydraulic pump 42 of the hydraulic pressure supply device 18 is stopped due to the engine stop, and the discharge hydraulic pressure becomes zero, and the pressure to the pressure holding part 20 is Although the oil pressure supply is stopped, the check valve 50 of the pressure holding unit 20 prevents a sudden drop in the oil pressure to the pressure control valves 26FL to 26RR, and thereafter the pressure in the supply side pipe 48s becomes less than the neutral pressure P,1. Then, the operating check valve 52 becomes fully closed and the pressure is maintained.

On the other hand, in the microprocessor 41b, even if the ignition switch 65 is turned off, the self-holding signal SS
continues to be in the on state, the power supply continues, the transition from step @ to step [phase] in Fig. 5 occurs, and the pressure command values PFL to P are changed until the predetermined time elapses.
By gradually returning RI to neutral pressure PM and thereby setting the pressure in the hydraulic cylinders 28FL to 28RR to neutral pressure PM, it is possible to prevent sudden changes in vehicle height when the pressure holding part 20 enters the pressure holding state. To prevent.

Thereafter, when a predetermined period of time has elapsed, the process moves from step [phase] to step [phase], and the self-holding signal SS is turned off to cut off the power supply to the control device 34.

Next, a second embodiment of the invention will be described with reference to FIG.

In this second embodiment, an abnormality is detected by determining whether one difference value ΔYl between the lateral acceleration detection values YGA and Yo of the lateral acceleration sensors 30A and 30B is within an allowable range. It is.

That is, in FIG. 9, the step @ of FIG. 6 moves to step @a, and the difference value ΔY+ becomes the lower limit tolerance value −Δ
It is determined whether or not it is within the range of Y and upper limit tolerance +ΔY, and if -ΔY - ΔY, <+ΔY, step [
phase] and the first and second abnormal time measurement timers TI
After clearing and Tz, return to the process shown in Fig. 5, and ΔY
When l≦−ΔY or ΔYI≧ΔY, the process moves to step @b, and it is determined whether the difference value ΔY is positive, and when ΔYl >O, step [phase] in FIG. ~@, and when ΔY is <0, the process moves to step @~[phase] in FIG.

According to this second embodiment as well, it is determined whether or not the difference value ΔYI is within the allowable range, and when the difference value ΔYI is outside the allowable range, the difference value ΔY
, is positive or not, and based on the result of the determination, the abnormality detection process similar to that shown in FIG. 6 is performed, so that the same effects as in the first embodiment can be obtained.

In addition, in each of the above embodiments, the lateral acceleration sensor 30A
, 30B has been described, but the case is not limited to this, and the vertical acceleration sensor 32F
Regarding R to 32RR, for example, the difference values ΔZA and ΔZ between the vertical acceleration detection value Z GFll of the front wheel side vertical acceleration sensor 32FR and the vertical acceleration detection value Z GIIL and Zcm of the rear wheel side vertical acceleration sensors 32RL and 32RR.
By calculating , it is possible to detect an abnormality in the acceleration sensor without making an erroneous judgment through the same process as in FIG. 6 or 9, and by using two sets of this for the longitudinal acceleration sensor 31, Similar abnormality detection can be performed.

Furthermore, in each of the above embodiments, there are three vertical acceleration sensors.
Although the case is explained above, the case is not limited to this, and a vertical acceleration sensor may also be provided at each wheel position to use a total of four vertical acceleration sensors, or two vertical acceleration sensors at the front and rear may be used. The vertical acceleration at the remaining two locations may be estimated using the sensor and the roll rate detector of the vehicle.

Furthermore, in each of the above embodiments, the lateral acceleration sensor 30
A, 30B, the active type suspension system equipped with the longitudinal acceleration sensor 31 and the vertical acceleration sensors 32FR to 32RR has been described, but the present invention can also be applied to an active type suspension equipped with any one of these acceleration sensor sets. obtain.

Furthermore, in each of the above embodiments, the pressure holding section 20 and the fail-safe valve 22 are common to each pressure control valve.
Although the case where the pressure holding part 20 and the fail-safe valve 22 are provided is not limited to this, the pressure holding part 20 and the fail-safe valve 22 may be provided separately.

Furthermore, in each of the above embodiments, the hydraulic pump 42
Although a case has been described in which the rotational driving force is obtained from the engine, the invention is not limited to this, and it goes without saying that a rotational driving source such as an electric motor can be applied.

Furthermore, the control n valves for the hydraulic suspension system are not limited to the pressure control valves 26FL to 26RR,
Other flow control type servo valves etc. can be applied.

Further, in each of the above embodiments, a case has been described in which hydraulic oil is used as the working fluid, but the present invention is not limited to this, and any working fluid can be used as long as it has a low compressibility.

Furthermore, in the above embodiment, the case where the present invention is applied to an active suspension has been described, but the present invention is not limited to this, and the application of the present invention is not limited to this. An abnormality may be detected.

〔Effect of the invention〕

As explained above, according to the present invention, the difference value between the acceleration detection values of two acceleration sensors is calculated by the difference value calculation means,
When this difference value is within the same polarity and exceeds the set value for a predetermined period of time, it is determined that one of the acceleration sensors is abnormal, so the acceleration component in the resonant frequency range of the acceleration sensor is It is possible to reliably prevent erroneous detection of an abnormality in the acceleration sensor when driving on a rough road, and to do so, the conditions (thresholds) that serve as the basis for abnormality judgment are expanded and the judgment time is extended. Since this is not necessary, effects such as being able to perform a quick fail-safe operation when a sensor abnormality occurs while ensuring high abnormality detection accuracy can be obtained.

[Brief explanation of drawings]

Fig. 1 is a basic configuration diagram showing a schematic configuration of the present invention, Fig. 2 is a hydraulic circuit diagram showing a first embodiment of the invention, and Fig. 3 is a characteristic showing the relationship between control pressure and command current of the pressure control valve. Fig. 4 is a block diagram showing an example of a control device; Fig. 5 is a block diagram showing an example of a control device;
6 and 6 are flowcharts each showing an example of a processing procedure of the control device, FIGS. 7 and 8 are time charts providing a detailed explanation of the present invention, and FIG. 9 is a control device in a second embodiment of the present invention. 3 is a flowchart illustrating an example of an abnormality detection processing procedure. In the figure, l0FL-10RR is a wheel, 12 is a wheel side member,
14 is a vehicle body side member, 16 is an active suspension, 18
20 is a hydraulic supply device (fluid supply device); 20 is a pressure holding unit;
22 is a fail-safe valve, 26FL to 26RR are pressure control valves, 28FL to 28RR are hydraulic cylinders (fluid cylinders), and 30A. 30B is a lateral acceleration sensor, 31 is a longitudinal acceleration sensor, 3
2FR to 32RR are vertical acceleration sensors, 34 is a control device, 6t is a microcomputer, and 62FL to 62RR are solenoid drive circuits. 5) 2 2" Figure λ+Electric"/le i Figure 7 Ten Tombs 9ヱ

Claims (1)

[Claims] (1) At least two acceleration sensors that detect acceleration in the same direction that occurs in a vehicle, a difference calculation means that calculates a difference between the acceleration detection values of both acceleration sensors, and a difference value of the difference calculation means that is the same. 1. An acceleration sensor abnormality detection device for a vehicle, comprising abnormality detection means for determining an abnormality when a state in which the polarity is within the polarity and exceeds a set value continues for a predetermined period of time.