Body swing control apparatus for industrial vehicles

• US 6,266,594 B1
• Filed: 04/16/1998
• Issued: 07/24/2001
• Est. Priority Date: 04/23/1997
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
• Original Assignee: Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
• Inventors: Ishikawa, Kazuo
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): TO, TUAN C
• Application Number:
  US09/061,389
• Time in Patent Office: 1,195 Days
• Field of Search: 701/50, 701/124, 701/213, 364/424.04, 340/438, 702/101, 702/102, 702/41, 702/42, 177/136, 177/1, 177/141
• US Class Current: 701/50
• CPC Class Codes: B60G 17/005 Suspension locking arrangements for retractable wheels B62D61/12
• CPC Class Codes: B60G 17/0162 mainly during a motion involving steering operation, e.g. cornering, overtaking B60G17/0164 takes precedence
• CPC Class Codes: B60G 2200/322 with a single pivot point and a straight axle
• CPC Class Codes: B60G 2204/46 Means for locking the suspension
• CPC Class Codes: B60G 2204/4605 hydraulically, e.g. interrupting communication between the chambers of a hydraulic cylinder
• CPC Class Codes: B60G 2300/022 Fork lift trucks, Clark
• CPC Class Codes: B60G 2400/0523 Yaw rate
• CPC Class Codes: B60G 2400/104 lateral or transversal with regard to vehicle
• CPC Class Codes: B60G 2400/204 Vehicle speed
• CPC Class Codes: B60G 2400/41 Steering angle
• CPC Class Codes: B60G 2400/61 Load distribution
• CPC Class Codes: B60G 2400/90 Other conditions or factors
• CPC Class Codes: B60G 2600/044 Alarm means
• CPC Class Codes: B60G 2800/0122 Roll rigidity ratio; Warping
• CPC Class Codes: B60G 2800/24 Steering, cornering
• CPC Class Codes: B60G 2800/9122 ARS - Anti-Roll System Control
• CPC Class Codes: B66F 17/003 for fork-lift trucks
• CPC Class Codes: B66F 9/07586 Suspension or mounting of wheels on chassis

Abstract

A rear axle which supports rear wheels is attached to the body of a vehicle in such a way as to be swingable up and down around a center pin. A controller detects the running state from detection values θ and V of a sensor for detecting the tire angle of the rear wheels and a sensor for detecting a vehicle speed, and detects the load state from detection values H and w of a height sensor and a pressure sensor. When a determination value derived from the detection values θ and V becomes equal to or greater than a set value which is determined in accordance with the detection values H and w, an electromagnetic changeover valve of a dumper is switched to carry out control to lock the rear axle. When a sensor is diagnoses as failing, maximum values θmax and Vmax or the like are selected as most severe detection values. Even one of a set of sensors fails, therefore, the rear axle will not be locked as long as the vehicle runs in such a way that the detection value of the other sensor allows the determination value to be smaller than the set value.

Claims

1. An apparatus equipped with a lock mechanism for locking an axle, supported swingable up and down on a body of a runnable and loading industrial vehicle, for a purpose of ensuring stable running of said vehicle, comprising:

a plurality of sensors for detecting at least one of a running state and a load state of said vehicle, and outputting detection values indicative thereof;

control means for receiving said detection values from said plurality of sensors, calculating a determination value based on said detection values from at least two of said plurality of sensors and activating said lock mechanism when said determination value is equal to or greater than a set value;

diagnosis means for diagnosing a failure of at least one sensor; and

setting means, included as part of said control means, for replacing the detection value from the sensor that has been diagnosed as failing by said diagnosis means with a predetermined detection value within a normal detection range of that sensor, whereby said control means does not activate said lock mechanism if the determination value that the control means calculates based on at least said predetermined detection value is less than said set value.

2. The apparatus according to claim 1, wherein said predetermined detection value is within a normal detection range of that failed sensor so as to make said determination value most likely to equal or exceed said set value.

3. The apparatus according to claim 2, wherein said control means does not activate said lock mechanism if the detection value of the other sensor for calculating said determination value takes such a value that the calculated determination value is less than said set value.

4. The apparatus according to claim 2, wherein said plurality of sensors include a plurality of first sensors for providing detection values necessary for calculating at least one of a centrifugal acceleration of said vehicle and a rate of change in yaw rate of said vehicle as determination values;

said control means activates said lock mechanism when said centrifugal acceleration or said rate of change in yaw rate, calculated from said detection values of said plurality of first sensors, becomes equal to or greater than said set value; and

said setting means sets said predetermined detection value as the detection value of a sensor among said plurality of first sensor that has been diagnosed as failing by said diagnosis means, in such a manner as to maximize said centrifugal acceleration or said rate of change in yaw rate within a normal detection range of said failing sensor.

5. The apparatus according to claim 4, wherein said first sensors include:

a sensor for detecting a tire angle of said industrial vehicle; and

a sensor for detecting a vehicle speed.

6. The apparatus according to claim 4, wherein said first sensors include:

a sensor for detecting a yaw rate of said vehicle; and

a sensor for detecting a vehicle speed.

7. The apparatus according to claim 4, further comprising a plurality of second sensors needed to detect a height of gravitational center of said vehicle;

and wherein

said control means activates said lock mechanism when said centrifugal acceleration becomes equal to or greater than a set value which is determined in accordance with said height of gravitational center of said vehicle; and

said setting means sets, as the detection value of a sensor among said plurality of second sensors that has been diagnosed as failing by said diagnosis means, such a value as to maximize said height of gravitational center of said vehicle within a normal detection range of said failing sensor.

8. The apparatus according to claim 7, wherein said second sensors include:

a height sensor for detecting a height of a loading unit provided on said vehicle for a loading purpose; and

a weight sensor for detecting a weight of a load on said loading unit.

9. The apparatus according to claim 8, wherein said diagnosis means diagnoses any sensor to be diagnosed as failing when the set value of that sensor keeps satisfying a preset failure condition for a predetermined time or longer.

10. An apparatus equipped with a lock mechanism for locking an axle, pivotably supported by a body of an industrial vehicle, for a purpose of ensuring stable running of the vehicle, wherein the vehicle has a steering wheel and a steered wheel that is steered with the steering wheel for turning the vehicle, the apparatus comprising:

a wheel angle sensor for detecting the wheel angle of the steered wheel;

a steering angle sensor for detecting the steering angle of the steering wheel;

a speed sensor for detecting the running speed of the industrial vehicle;

a first processor for computing a determination value representing a running state of the vehicle based on the detected wheel angle and the detected running speed when the wheel angle sensor is normal;

a second processor for computing the determination value based on the detected steering angle and the detected running speed when the wheel angle sensor fails; and

a controller for controlling the lock mechanism, wherein the controller activates the lock mechanism to lock the axle when the determination value is equal to or greater than a predetermined value.

11. The apparatus according to claim 10, wherein the determination value is at least one of a centrifugal acceleration acting on the vehicle and the rate of change in the centrifugal acceleration.

12. The apparatus according to claim 10, wherein the determination value is at least one of a centrifugal acceleration acting on the vehicle and the rate of change in a yaw rate.

13. The apparatus according to claim 10, further comprising means for comparing the detected steering angle with the detected wheel angle wherein the comparing means determines the wheel angle sensor as failing when the detected wheel angle does not change even though the detected steering angle is changing.

14. The apparatus according to claim 10, further comprising means for determining a disconnection originated failure or a short-circuiting originated failure when the detected wheel angle is out of a predetermined normal range.

15. An apparatus equipped with a lock mechanism for locking an axle, supported swingable up and down on a body of a runnable and loading industrial vehicle, for a purpose of ensuring stable running of said vehicle, comprising:

detection means for detecting a running state of said vehicle;

prediction means for predicting a centrifugal acceleration to be applied to said vehicle based on a result of detection by said detection means;

determination means for determining if said centrifugal acceleration predicted by said prediction means becomes equal to or greater than a reference value set at a first value, when said lock mechanism is not locking said axle; and

control means for outputting a centrifugal acceleration countermeasure signal to prevent frequent switching between the locked state and the unlocked state of said axles whereby, when said lock mechanism is locking said axle, said centrifugal acceleration countermeasure signal reduces said reference value to a second value which is less than said first value, and said axle is unlocked when said centrifugal acceleration becomes less than said second value.

16. The apparatus according to claim 15, wherein said detection means includes:

first detection means for detecting a vehicle speed of said vehicle; and

second detection means for detecting a tire angle of said vehicle.

17. The apparatus according to claim 16, wherein said prediction means predicts the centrifugal acceleration based on the vehicle speed and the wheel angle.

18. The apparatus according to claim 15, wherein said detection means includes a yaw rate sensor for detecting a yaw rate to be applied to said vehicle, and said prediction means predicts a centrifugal acceleration currently applied to said vehicle based on said yaw rate detected by said yaw rate sensor.

19. An apparatus equipped with a lock mechanism for locking an axle, pivotably supported by a body of an industrial vehicle, for ensuring stability of the vehicle, comprising:

a plurality of sensors for detecting a vehicle state including at least one of a running state and a load state of the vehicle, wherein the sensors generate detection values representing the vehicle state;

a controller for controlling the lock mechanism, wherein the controller determines the vehicle state based on the detection values of the sensors, and wherein the controller activates the lock mechanism to lock the axle when the vehicle state satisfies a predetermined lock condition;

test means for testing a failure of at least one sensor; and

substituting means for substituting an assumed value for the detection value of the sensor that has been detected as failing, wherein, when the sensor failure is detected, the controller determines an assumed vehicle state based on the assumed value corresponding to the failed sensor and the detection value of the normally functioning sensor, and the controller controls the lock mechanism in accordance with the assumed vehicle state, wherein the substituting means determines the assumed value with a conservative bias towards causing the assumed vehicle state to satisfy the lock condition.

20. The apparatus according to claim 19, wherein each sensor generates the detection value between a predetermined minimum value and a predetermined maximum value when normally functioning, wherein the assumed value corresponds to the maximum value of the detection value of the sensor that has been detected as failing.

21. The apparatus according to claim 19, wherein the sensors include a plurality of first sensors for generating detection values representing the running state of the vehicle and a plurality of second sensors for generating detection values representing the height of the center of gravity of the vehicle, wherein the controller computes a determination value based on the detection values of the first sensors and computes a set value based on the detection values of the second sensors, and wherein the controller determines that the vehicle state satisfies the lock condition when the determination value is equal to or greater than the set value.

22. The apparatus according to claim 21, wherein each sensor generates the detection value between a predetermined minimum value and a predetermined maximum value when normally functioning, wherein the assumed value corresponds to the maximum value of the detection value of the sensor that has been detected as failing.

23. The apparatus according to claim 21, wherein the assumed value corresponding to the failed first sensor causes the determination value to increase, wherein the assumed value corresponding to the failed second sensor causes the set value to decrease.

24. The apparatus according to claim 21, wherein the determination value is at least one of a centrifugal acceleration acting on the vehicle and the rate of change of a yaw rate.

25. The apparatus according to claim 19, further comprising a display for displaying the axle being locked.

26. The apparatus according to claim 25, wherein the display includes a lamp installed in a meter box of the vehicle.

27. An apparatus equipped with a lock mechanism for locking an axle, which is pivotably supported by a body of an industrial vehicle, for ensuring stability of the vehicle, comprising:

detection means for detecting a vehicle state including at least one of a running state and a load state of the vehicle;

a controller for controlling the lock mechanism, wherein the controller activates the lock mechanism to lock the axle when the vehicle state satisfies a predetermined lock condition; and

prediction means for predicting the centrifugal acceleration to be applied to the vehicle based on a result of detection by the detection means, wherein, when the predicted centrifugal acceleration is greater than a predetermined reference value while the lock mechanism is locking the axle, the controller generates a warning signal to warn that the running state of the vehicle is unstable.

28. The apparatus according to claim 27, wherein the vehicle has a steered wheel that is steered for turning the vehicle, wherein the detection means includes:

a speed sensor for detecting the speed of the vehicle; and

a wheel angle sensor for detecting the wheel angle of the steered wheel.

29. The apparatus according to claim 28, wherein the prediction means predicts the centrifugal acceleration based on the vehicle speed and the wheel angle.

30. The apparatus according to claim 27, wherein the detection means includes a yaw rate sensor for detecting a yaw rate to be applied to the vehicle, and the prediction means predicts the centrifugal acceleration based on the detected yaw rate.

31. The apparatus according to claim 27, further comprising an alarm device for generating an alarm in response to the warning signal.