JPH04121214A - Suspension for vehicle - Google Patents

Abstract

PURPOSE:To discover a steering angle sensor failure during use of a vehicle by judging as the steering angle sensor failure if a change amount of a stroke detection signal of a hydraulic cylinder for controlling suspension characteristic exceeds a predetermined value for a predetermined time when car speed is more than a predetermined speed and a detected turning state is gentle. CONSTITUTION:A control unit 45 controls working fluid for a hydraulic cylinder 12 by information of various sensors including a car speed sensor 62, a steering angle sensor 63 and a ground clearance sensor 58. In this case, when car speed detected by a car speed sensor is less than a predetermined car speed and a turning state acquired from a detected steering angle of a steering angle sensor 63 is gentle, if a change amount of a detection signal of a stroke of the hydraulic cylinder 12 acquired from the ground clearance sensor 58 continues to exceed a predetermined threshold value for a predetermined period of time, it is judged as a failure of the steering angle sensor 63. Thus, the steering angle sensor failure can be detected during use of a vehicle.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a suspension system for a vehicle, and more specifically, to a suspension system for a vehicle by supplying and discharging working fluid to and from a cylinder installed between a vehicle body and wheels. This invention relates to a suspension device whose characteristics can be changed.

(Prior Art) For example, as shown in Japanese Unexamined Patent Publication No. 83-130418, a hydraulic cylinder is installed between the vehicle body and the wheels, and suspension characteristics are improved by controlling the supply and discharge of working fluid to and from the cylinder. A suspension device for a vehicle that can freely change the amount of suspension is known.

In many cases, this type of so-called active control suspension system controls the supply and discharge of working fluid based on the vehicle height of each wheel and the vertical acceleration applied to the vehicle body.
It is controlled by feedback of lateral acceleration, etc. In addition, it has also been considered to use the steering wheel steering angle as a condition for controlling the supply and discharge of working fluid.

That is, for example, when the vehicle turns, the supply and discharge of the working fluid can be oven-controlled in accordance with the steering angle detected by the steering angle sensor to perform a so-called reverse roll. By doing so, it is possible to compensate for the problem that the feedback control described above cannot achieve good roll control in the transient region at the beginning of a turn due to the response delay of the control system.

(Problems to be Solved by the Invention) Currently, the above-mentioned steering angle sensor that detects the steering angle is more likely to fail than, for example, a vehicle speed sensor. If the steering angle sensor remains malfunctioning and the supply and discharge of the working fluid is controlled based on its output, it will naturally be impossible to achieve the desired suspension characteristics.

However, in the past, no measures have been taken to quickly discover a malfunction in the steering angle sensor while the vehicle is being used. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a suspension system for a vehicle that can quickly detect a malfunction of the steering angle sensor while using the vehicle normally. (Means for Solving the Problems) The first vehicle suspension device according to the present invention is capable of determining a failure when the steering angle sensor remains in a fixed signal state with a value near zero steering angle. As mentioned above, the suspension is configured so that the suspension characteristics can be changed by supplying and discharging working fluid to and from hydraulic cylinders installed between the vehicle body and the wheels. In a vehicle suspension system that is equipped with a steering angle sensor as one of the means for detecting conditions for controlling characteristics, there is a vehicle speed sensor that detects the speed of the vehicle, and a stroke sensor that detects the piston stroke of a hydraulic cylinder. and, when the vehicle speed indicated by the vehicle speed sensor is equal to or higher than a predetermined speed and the vehicle turning state determined based on the output of the steering angle sensor is gentler than the predetermined state, the amount of change in the output signal of the stroke sensor is set to a predetermined value. The present invention is characterized in that it is provided with a failure determination means that determines that the steering angle sensor is malfunctioning if the condition in which the steering angle sensor exceeds the threshold value continues for a predetermined period or more.

Note that in this first vehicle suspension device, the failure determination means is configured to select, as the thresholds, a first threshold and a second threshold that is larger than the first threshold. and when the amount of change in the output signal of the stroke sensor exceeds the first threshold value continues for a first predetermined period or longer, or when the state exceeds the second threshold value, the first predetermined value is set. It is preferable that the steering angle sensor is determined to be malfunctioning when it continues for a second predetermined period or longer, which is shorter than the period.

Further, a second vehicle suspension device according to the present invention includes:
If the steering angle sensor remains in a fixed state with a large steering angle value, it is possible to determine a failure, and similarly to the first suspension device, it supplies working fluid to the hydraulic cylinder. In a suspension system for a vehicle that is equipped with a steering angle sensor similar to the one described above, the vehicle speed sensor includes a vehicle speed sensor that detects the speed of the vehicle, a stroke sensor that detects the piston stroke of a hydraulic cylinder, and a vehicle speed sensor that detects the piston stroke of a hydraulic cylinder. When the indicated vehicle speed is equal to or higher than a predetermined speed, the direction of vehicle turning determined based on the output of the steering angle sensor and the vehicle body roll direction indicated by the output signal of the stroke sensor do not match for a predetermined period of time or more. If so, the present invention is characterized by providing a failure determination means for determining that the steering angle sensor is malfunctioning.

(Operations and Effects of the Invention) In the first suspension device described above, if the vehicle speed is higher than a predetermined speed and the output signal change amount of the stroke sensor continues to be higher than a predetermined threshold for a predetermined period or longer, it means that the vehicle is turning. This is considered to be a case where the vehicle body is rolling to some extent.

In such a case, if the vehicle turning state determined based on the output of the steering angle sensor is slower than the predetermined state, it means that the steering angle sensor remains in the signal fixed state while indicating a value near zero steering angle. It can be considered that

Furthermore, even if the vehicle momentarily runs onto a curb while traveling straight, a state will occur where the change in the output signal of the stroke sensor exceeds the predetermined threshold value when the vehicle speed exceeds the predetermined speed, as described above. It turns out. In this state, even if the steering angle sensor is normal, the vehicle turning state determined based on its output will be gentler than in the predetermined state. However, unlike when the vehicle is turning, this condition only occurs for a short moment, so if the above predetermined period is set appropriately, this condition can be caught and regarded as a failure of the steering angle sensor. It never gets put away.

Furthermore, if the failure determination means is configured as described in claim 2, when the amount of change in the output signal of the stroke sensor is significant enough to exceed the relatively large second threshold, the condition is By determining that the steering angle sensor has failed when the steering angle sensor continues for a short second predetermined period or longer, it is possible to determine the failure within a short period of time.

In the failure determination means having the above configuration, if the amount of change in the output signal of the stroke sensor is not so remarkable and exceeds a relatively small first threshold value, then the condition is determined by a relatively long first predetermined threshold value. By determining that the steering angle sensor has failed when the steering angle sensor continues for a certain period of time, the reliability of failure determination can be increased.

On the other hand, in the second suspension device of the present invention, if the vehicle speed is equal to or higher than the predetermined speed and the output signal of the stroke sensor indicates vehicle body roll, it is considered that the vehicle is turning. At this time, if the direction of the vehicle turning determined based on the output of the steering angle sensor and the vehicle body roll direction indicated by the output signal of the stroke sensor do not match for a predetermined period or more, it is determined that the steering angle sensor This means that the signal can be considered to be in a fixed state while indicating a steering angle in the opposite direction to the actual steering angle.

As described above, according to the present invention, failure of the steering angle sensor can be determined reliably and early, and the safety and reliability of the suspension device are greatly improved.

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 1 shows a suspension system for a vehicle according to an embodiment of the present invention, and FIG. 2 shows a hydraulic circuit used in this suspension system. In addition, in the figure,
The main elements corresponding to the right front wheel, left front wheel, right rear wheel, and left rear wheel are numbered rFRJ rFLJ, respectively.
The symbols rRRJ and rRLJ are shown with added symbols, but in the following explanation, those symbols will be added only when it is particularly necessary.

As shown in FIG. 1, a hydraulic cylinder 12 is fixed to the vehicle body 11 for each wheel, and a hydraulic chamber 14 is defined by a piston 13 that is slidably inserted into the hydraulic cylinder 12. has been done. A wheel 10 is held on a piston rod 15 that is integrated with the piston 13. A gas spring 21 is communicated with the hydraulic pressure chamber 14 via a hydraulic passage. The gas spring 21 has a gas chamber 25 defined by a diaphragm 23 as a movable partition wall and a liquid chamber 27, and the liquid chamber 27 is communicated with the hydraulic pressure chamber 14.

In addition, as shown in detail in FIG. 2, in this embodiment, the gas spring 2
1 are provided for each width, and they are connected to the hydraulic cylinder 12 in a parallel relationship with each other. An orifice 29 is provided in each of the hydraulic passages 18 that communicate with each of these gas springs 21 . Such a hydraulic cylinder 12, gas spring 21 and orifice 29
The unit consisting of the combination of the above has a basic function as a suspension device due to the buffering effect of the gas spring 21 and the damping effect of the orifice 29.

The above-mentioned hydraulic cylinder 12 has a high pressure pipe 31F or 3
1R is connected and hydraulic cylinder 1 is connected through these pipes.
Hydraulic fluid is supplied and discharged to and from 2. Note that each of the high pressure pipes 31F and 31R has a flow control valve 9F.
, 9R are interposed, and these flow control valves 9 control the supply and discharge of hydraulic fluid to and from each cylinder 12 to adjust the cylinder internal pressure.

Hereinafter, a hydraulic circuit for supplying and discharging this hydraulic fluid will be explained with reference to FIG. 2. The vane pump 32 driven by the engine 8° pumps up the hydraulic fluid 44 from the reservoir tank 33 and passes the hydraulic fluid 44 through the common high-pressure pipe 34 to the high-pressure pipes 31F and 31 for the front wheels and the rear wheels, respectively.
Force feed to R. This common high pressure pipe 34 is provided with a check valve 35, a filter 36, a main accumulator 37 for accumulating pressure, and a hydraulic pressure gauge 38 in this order from the upstream side. Further, an in-pump relief valve 30 is provided in the pump 32 to circulate the discharged hydraulic fluid 44 to the suction side when the discharge side pressure increases abnormally.

The high pressure pipe 31F for the front wheel is the high pressure pipe 31FR1 for the right front wheel.
It is branched into a high pressure pipe 31FL for the left front wheel, and each of these pipes 31F R and 81F L is connected to a flow control valve 9FR.
, 9RL are connected to the respective hydraulic pressure chambers 14 of the right front wheel hydraulic cylinder 12FR and the left front wheel hydraulic cylinder 12FL through the inflow valves 52F R and 52F L forming the front right wheel hydraulic cylinder 12FR and the front left wheel hydraulic cylinder 12FL, respectively. The flow control valve 9 includes the above-mentioned inflow valve 52 and a discharge valve 53 interposed in the recirculation pipe 40F that returns the hydraulic fluid 44 to the reservoir tank 33. Both the inlet valve 52 and the outlet valve 53 can take an open position and a closed position, and have a built-in differential pressure valve that maintains the hydraulic pressure at a predetermined value in the open position.

Further, a pilot passage 39F is branched from the high pressure pipe 31F, and this pilot passage 39F is connected to pilot pressure responsive check valves 50F R and 50F L. Each check valve 50 uses a pilot passage 39F to control the operating oil pressure (accumulated oil pressure and main pressure by the main accumulator 37) in the high pressure piping 31 on the upstream side of the inflow valve 52.
This pilot pressure is, for example, 40 kg gf/
It closes when it is less than cd. In other words, when the main pressure is 40) c g f /cd or more,
It becomes possible to supply and discharge hydraulic fluid to and from the hydraulic cylinders 12FR and 12FL.

In addition, the high pressure distribution f31FH for the right front wheel has a relief valve 54F.
R, and a hydraulic pressure gauge 55FR is provided. On the other hand, there is also a relief valve 54FL in the high pressure piping 31FL for the left front wheel.

A hydraulic pressure gauge 55FL is provided. Relief valve 54FR
, 54PL opens when the internal pressure of the hydraulic cylinder 12FRS12FL increases abnormally, and the hydraulic oil? &44 is returned to the reflux pipe 40F. A return accumulator 59F is attached to this recirculation passage 40F, which functions to accumulate pressure when the hydraulic fluid 44 is discharged from the hydraulic cylinder 12FR112FL.

Exactly the same elements as the front wheel elements described above are also provided on the rear wheel high pressure pipe 31R side. In FIG. 2, the front wheel element and the rear wheel element, which are equivalent to each other, are distinguished by the symbols rFJ and rRJ added next to their respective numbers.

The front wheel side reflux pipe 40F and the rear wheel side reflux pipe 40R are connected to a common reflux pipe 41 that reaches the reservoir tank 33 via a cooling circuit 46. The common reflux pipe 41 and the common high pressure pipe 34 are communicated with each other by a relief pipe 42, and the relief pipe 42 has an unload valve 4.
3 is interposed. The operation of this unload valve 43 is controlled by a control unit 45 (see FIG. 1) that receives the output of the oil pressure gauge 38, and when the main pressure exceeds a predetermined upper limit (-160 kgf/cI# as an example). The vane pump 32 is opened and the vane pump 32 is unloaded, and the main pressure reaches a predetermined lower limit (-120 k
g f /cj) or less. When the main pressure falls below the lower limit, the control unit 4
5, the unload valve 43 is closed to place the vane pump 32 in a loaded state.

As a result, the main pressure increases to the above upper limit value.

In this way, the main pressure is within a predetermined range (120 to 160 kgf
/d).

Further, the common reflux pipe 41 and the common high pressure pipe 34 are communicated with each other by a relief pipe 47.
7 is provided with a fail-safe valve 48. This fail-safe valve 48 has the function of being switched to the open position in the event of a failure of other valves, returning the oil stored in the main accumulator 37 to the reservoir tank 33, and canceling the high pressure state. Note that check valves 50F R and 50 are provided in the pilot passage 39F when the fail-safe valve 48 is opened.
A throttle 51F is provided to delay the closing operation of F.L.

Next, the operation of the suspension device having the above configuration will be explained. The operations of the unload valve 43, fail-safe valve 48, inflow valve 52, and outflow valve 53 are controlled by a control unit 45 consisting of, for example, a microcomputer. The control unit 45 includes the hydraulic pressure gauge 38, a hydraulic pressure gauge 55 provided for each hydraulic cylinder 12,
Vertical acceleration sensor 57 detects sprung mass acceleration for each wheel 10FR, 10FL, 10RR, 10RL, and vehicle height sensor 58 similarly detects vehicle height (that is, cylinder piston stroke) for each wheel 10FR, 10FL, 10RR, 10RL. , a lateral acceleration sensor 61 that detects lateral acceleration applied to the vehicle body 11, a vehicle speed sensor 62, and a steering angle sensor 63 that detects the front wheel steering angle. As for the vertical acceleration sensor 57 and the vehicle height sensor 58, the left rear wheel 10R
Only those corresponding to L are shown).

The control unit 45 includes oil pressure gauges 5 for each wheel.
5. Vertical acceleration sensor 57 for each wheel, vehicle height sensor 58,
Based on the cylinder internal pressure, sprung mass acceleration, vehicle height, and lateral acceleration indicated by the lateral acceleration sensor 61, the supply and discharge of the hydraulic fluid 44 is feedback-controlled.

By supplying and discharging the hydraulic fluid 44 to and from the hydraulic cylinder 12 in this manner, the same effect as changing the throttling resistance of the orifice 29 and the elastic modulus of the gas spring 21 can be obtained.
The suspension device functions as a so-called active suspension device. It is also possible to control the vehicle height for each wheel by controlling the amount of hydraulic fluid in the hydraulic cylinder 12. Therefore, for example, it is possible to make the vehicle body roll angle zero when the vehicle turns using the feedback control described above.

Next, reverse roll correction processing using the aforementioned steering angle sensor 63 will be explained. FIG. 3 shows the flow of this process by the control unit 45. As illustrated, in step P1, the control unit 45
The lateral acceleration G is calculated from the vehicle speed V indicated by the output signal of the vehicle speed sensor 62 and the steering angle θ indicated by the output signal of the steering angle sensor 63. Then, in step P2, it is determined whether the calculated absolute value IGI of the lateral acceleration G is greater than or equal to a predetermined value 00, and if not, the flow of processing returns to step P1.

If it is 61268 or more, the control unit 45
In step P3, the turning direction of the vehicle is determined from the direction of the calculated lateral acceleration G.

If the vehicle is turning right, in step P4, the supply and discharge of hydraulic fluid 44 to and from hydraulic cylinders 12FR, 12FL, L2RR, and 12RL are controlled to be open so as to apply reverse roll correction in the right turning direction.

This supply/discharge of the hydraulic oil 44 is controlled so that the outer wheel side vehicle height increases, for example, by about 2 mm each time.

This hydraulic fluid supply and discharge control is performed in the next step P5.
This process is repeated until it is determined that the calculated value of IG+ has converged to less than 00.

If the vehicle is turning to the left, reverse roll correction is performed in step P6 and step 7 in the same manner as described above.

As explained above, by performing reverse roll correction using oven control, it is possible to compensate for the problem that the feedback control described above cannot achieve good roll control in the transient region at the beginning of a turn due to the response delay of the control system. I can do it.

Next, a process for detecting that the steering angle sensor 63 is in a signal fixed state while indicating a value near zero in the steering angle will be described. FIG. 4 shows the flow of this process by the control unit 45.

As shown, the control unit 45 performs step p
At H, the lateral acceleration G is calculated from the vehicle speed ■, which is indicated by the output signal of the vehicle speed sensor 62, and the steering angle θ, which is indicated by the output signal of the steering angle sensor 63.

Next, in step P12, the vehicle speed ■ is set to a predetermined value V.
(It is determined whether the number is 1 or more, and if not, the process flow returns to the beginning and starts the next process.

If the vehicle speed V is equal to or higher than the predetermined value VQ, then step P
At step 13, it is determined whether or not the calculated absolute value IGi of the lateral acceleration G is less than a predetermined value 01. If not, the process flow returns to the beginning and the next process begins.

On the other hand, when IGI<Gl, that is, when it is determined that the vehicle turning state is gentler than the predetermined state corresponding to the predetermined value G1, then in step P14, for example, the vehicle height sensor 58 for one front wheel is Output signal is captured. This output signal indicates the piston stroke X of the hydraulic cylinder 12FR or 12FL. Then, in step P15, it is determined whether the absolute value of this stroke X exceeds a predetermined first threshold value Xl. If not, the process flow returns to the beginning and the next process begins.

On the other hand, if it is determined that 1x1>xl, then in step P16 it is determined whether the value of lxl exceeds a predetermined second threshold value XZ (XI < Xl). Ru. If IX〉Xl, then
Next, in step P1.7, 1 is added to an index n (initial setting value is O) indicating that the processing flow has passed.

Next, in step P1g, it is determined whether the index n is 2 or not. The process flow starts with step P1
7. When passing through Plg, since n=-1, the process flow returns to the beginning and the next process starts.

In the next series of processing, Xl>
When it is determined that it is Xl, it is determined that it is n-2 in step P18.

The processes from step pH to step P18 described above are performed, for example, in about several tens of milliseconds. The fact that XI>Xl has been determined twice at such time intervals means that the vehicle body 11 is rolling, considering that the vehicle speed V is greater than or equal to the predetermined value VO. Nevertheless, the fact that it was determined in step P13 that l G l < Gl, that is, the vehicle turning state is gentler than the predetermined state, means that the steering angle sensor 63, which is the basis for calculating this lateral acceleration G, It can be considered that the output signal of is in a fixed state while incorrectly indicating a value near zero steering angle.

Therefore, in this case, in step P19,
The active control of the suspension is stopped, and a series of processes related to failure determination of the steering angle sensor 63 are completed.

On the other hand, in step P16 described above, if it is determined that IXl>xl is not satisfied (that is, Xl <X1≦x2
), the process flow moves to step P20, which is similar to step P17, and then moves to step P21, which is similar to step P18. However, in this step P21, unlike step P18, it is determined whether or not the index n is 5, and when it is n-5, step P19
Active suspension control is discontinued.

As described above, when xl<lxl≦X2 and the value of lxl is relatively small, this state continues for more than a relatively long first predetermined period (that is, a period of five treatments from step pH to step P21). By regarding this as a failure of the steering angle sensor, the reliability of failure determination can be increased.

On the other hand, if the values of I x l > By regarding this as a steering angle sensor failure, it becomes possible to determine the failure within a short time.

Note that the values of n determined in steps PLli and P2L are not limited to 2 and 5, respectively, and in particular, l x
In the case of l>xl, the active control may be immediately stopped once this is determined. However, if the active control is stopped after reaching nx2 as in the above embodiment, the steering angle sensor 63 will malfunction when the vehicle momentarily runs onto a curb while traveling straight. This is preferable because it prevents a determination that there is a problem.

Next, a process for detecting that the steering angle sensor 63 is in a signal fixed state while indicating a large steering angle value will be described. FIG. 5 shows the flow of this process by the control unit 45. As shown in the figure, the control unit 45 controls the vehicle speed sensor 6 in step P31.
The lateral acceleration G is calculated from the vehicle speed ■ indicated by the output signal of No. 2 and the steering angle θ indicated by the output signal of the steering angle sensor 63.

Next, in step P32, the vehicle speed V is set to a predetermined value V.

It is determined whether or not this is the case, and if not, the flow of processing returns to the beginning and the next processing is started.

If the vehicle speed V is greater than or equal to the predetermined value v (1), the control unit 45 next in step P33 sets the internal pressures PPR%P of the front wheel hydraulic cylinders 12F R, 12F L,
The output signals of oil pressure gauges 55F R and 55F L indicating the work are taken in. These internal pressures P PRs P PL correspond to the piston strokes of the hydraulic cylinders 12FR and 12FL, respectively.

Next, in step P34, it is determined whether the absolute value IG1 of the lateral acceleration G calculated above is equal to or greater than a predetermined value 61. If not, the process flow returns to the beginning and the next process begins.

On the other hand, when IGI≧G, that is, when it is determined that the vehicle turning state is steeper than the predetermined state corresponding to the predetermined value G1, then in step P35, the direction of the calculated lateral acceleration G is The turning direction of the vehicle is determined based on this. When it is determined that the vehicle is turning to the right,
In step P38, PPL PPII>P
It is determined whether or not the value is O (PO is a predetermined threshold). If PFL PFR>-Po, it can be considered that the vehicle is truly turning to the right, and the flow of processing returns to the beginning.

On the other hand, if PPL PPR> PO, the internal pressures P□, PFI- of the hydraulic cylinders 12FR, 12FL
If it is considered that the vehicle is turning left based on , then in step P37, 1 is added to an index n (initial setting value is 0) indicating that the process flow has passed. Next, in step P3g, it is determined whether the index n is 3 or not. When the processing flow passes through step P37 for the first time, since it is n-1, the processing flow returns to the beginning and the next processing starts.

Also in the next and subsequent series of processes, PPL PPR>P in step P3B. When it is determined that the number is not, n-3 is determined in step P3g. The processes from step P31 to step P38 described above are also performed in about tens of milliseconds, for example. The fact that it has been determined that PFL PFR>PO is not satisfied three times at such time intervals means that the vehicle body 11 is turning left, considering that the vehicle speed V is greater than or equal to the predetermined value VO.

Nevertheless, the fact that it was determined to be a right turn in step P35 means that the output signal of the rudder angle sensor 63 remains fixed while indicating a relatively large rudder angle in the opposite direction to the actual one. It can be considered that there is. Therefore, in this case, the active control of the suspension is then stopped in step P39, and the series of processes related to the failure determination of the steering angle sensor 63 is completed.

On the other hand, when it is determined in step P35 that the turn is to the left,
In step P40, it is determined whether PPRP,L>po. PFRP, L>p.

If so, it can be considered that the vehicle is really turning left, so the process flow returns to the beginning and the next process starts.

On the other hand, if PPRPFL > p, that is, the internal pressure of the hydraulic cylinder L2F R, 12F L
If it is considered that the vehicle is turning to the right based on L, the process flow then moves to step P37. Hereinafter, a failure determination of the steering angle sensor 63 is made in the same manner as in the above case, and when it is determined that the steering angle sensor 63 has failed, active control of the suspension is stopped.

In the above embodiment, when it is determined that the steering angle sensor 63 is malfunctioning, the active control is stopped, or in addition to this, a warning is simply issued when it is determined that the steering angle sensor is malfunctioning. In this case, necessary measures such as canceling the active control may be manually operated by the driver.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a suspension device according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing a hydraulic circuit used in the suspension device, and FIG. 3 is a reverse roll diagram in the above embodiment device. FIG. 4 is a flowchart showing correction control; FIG. 4 is a flowchart showing a steering angle sensor failure determination process in the device of the embodiment; FIG. 5 is a flowchart showing another steering angle sensor failure determination process in the device of the embodiment. 10... Wheels 11... Vehicle body 12...
・Hydraulic cylinder 13...Piston 14...Hydraulic pressure chamber 15 of the hydraulic cylinder 15...Piston rod 18...Hydraulic pressure passage 21
...Gas spring 31...High pressure piping 32...
・Pump 37.59...Accumulator 38.55...Hydraulic pressure gauge 39...Pilot passage 40...Recirculation passage 43...Unload valve 44...Hydraulic oil 45...Control unit 48 ... Failsafe valve 52 ... Inflow valve 53 ... Outflow valve 57 ... Vertical acceleration sensor 58 ... Vehicle height sensor 61 ... Lateral acceleration sensor 62 ... Vehicle speed sensor 63 ...
- Rudder angle sensor 80...Engine diagram

Claims (3)

[Claims] (1) It is configured to be able to change the suspension characteristics by supplying and discharging working fluid to a hydraulic cylinder installed between the vehicle body and the wheels, and detects conditions for controlling the suspension characteristics. A suspension system for a vehicle in which a steering angle sensor is provided as one of the means includes: a vehicle speed sensor that detects the speed of the vehicle; a stroke sensor that detects a piston stroke of a hydraulic cylinder; and a vehicle speed that the vehicle speed indicated by the vehicle speed sensor is a predetermined speed. In the above, and when the vehicle turning state determined based on the output of the steering angle sensor is gentler than a predetermined state, the state in which the amount of change in the output signal of the stroke sensor exceeds a predetermined threshold is maintained for a predetermined period of time. A suspension device for a vehicle, characterized in that a suspension device for a vehicle is provided with a failure determining means that determines that the steering angle sensor is malfunctioning if the above condition continues. (2) The failure determination means sets a first threshold value and a second threshold value larger than the first threshold value as the threshold value, and the amount of change in the output signal exceeds the first threshold value. The steering angle sensor 2. The vehicle suspension device according to claim 1, wherein the vehicle suspension device is configured to determine that the suspension device is malfunctioning. (3) It is configured to be able to change the suspension characteristics by supplying and discharging working fluid to a hydraulic cylinder installed between the vehicle body and the wheels, and detects conditions for controlling the suspension characteristics. A suspension system for a vehicle in which a steering angle sensor is provided as one of the means includes: a vehicle speed sensor that detects the speed of the vehicle; a stroke sensor that detects a piston stroke of a hydraulic cylinder; and a vehicle speed that the vehicle speed indicated by the vehicle speed sensor is a predetermined speed. In the above case, if the direction of vehicle turning determined based on the output of the steering angle sensor and the vehicle body roll direction indicated by the output signal of the stroke sensor continue for a predetermined period or longer, A suspension device for a vehicle, comprising a failure determination means for determining that a steering angle sensor is malfunctioning.