GB2222560A

GB2222560A - Road vehicle stability indicating system

Info

Publication number: GB2222560A
Application number: GB8821198A
Authority: GB
Inventors: David F Short
Original assignee: Gloster Saro Ltd
Current assignee: Gloster Saro Ltd
Priority date: 1988-09-09
Filing date: 1988-09-09
Publication date: 1990-03-14
Also published as: GB8821198D0

Abstract

The stability indicating system e.g. for long articulated vehicles, container transport vehicles and tanker vehicles, includes means (14, 15) for monitoring the road speed and angle of steer of the vehicle and provides an audible and/or visual indication (12) in the driver's cab of an approaching condition of instability. The monitoring means preferably monitors not only the angle of steer but also the rate of steer and may additionally include means (16,17) for monitoring relative movements between the vehicle axles and the tractor, trailer or vehicle chassis. The warning is preferably progressive, for example, an audible warning can become louder or a visual flashing indicator can increase its rate of flashing as the instability point is more closely approached. The warning should, of course, be given sufficiently in anticipation of the instability point to give a comparatively unskilled driver the opportunity to take corrective action. <IMAGE>

Description

ROAD VEHICLE STABILITY INDICATING SYSTEM Field of the Invention This invention relates to a system for indicating the stability (or instability) of a road vehicle.

Background to the Invention A problem exists in the operation of heavy road vehicles, and particularly in the case of long articulated trucks, contrainer transport vehicles and fuel tankers in that an individual vehicle can, when turning, reach an instability point where only an experienced driver is able to take the required corrective action. Such an instability point can be reached when a vehicle is travelling at either high or low speed; and, when it occurs, the vehicle may turn over or go out of control if the driver does not immediately take, or is not capable of taking, the appropriate action to correct the situation.

It is accordingly an object of the present invention to provide an indicating system, the use of which obviates this problem.

Summary of the Invention According to the present invention there is provided a stability indicating system for a road vehicle which includes means for monitoring the road speed and angle of steer of the vehicle and which provides an audible and/or visual indication in the driver 5 cab of an approaching condition of instability.

The monitoring means preferably monitors not only the angle of steer but also the rate of steer. The monitoring means may additionally include means for monitoring relative movements between the vehicle axles and the tractor, trailer or vehicle chassis.

The warning is preferably progressive, for example, an audible warning can become louder or a visual flashing indicator can increase its rate of flashing as the instability point is more closely approached. The warning should, of course, be given sufficiently in anticipation of the instability point to give a comparatively unskilled driver the opportunity to take corrective action.

The system is preferably calibrated in accordance with the vehicle parameters, i.e. in regard to height of the vehicle, length, axle arrangements and so forth.

Feedback means may be provided whereby, as the vehicle approaches an instability condition, the effort required to effect turning of the wheel in the direction corresponding to instability is increased.

Brief Description of the Drawings Figure 1 illustrates schematically a stability indicating system for an articulated vehicle, and Figure 2 shows a steering sensor arrangement.

Description of the Preferred Embodiments As shown in Figure 1, an articulated road vehicle 11 includes a tractor unit llA and a trailer unit llB and there is an electronic vehicle stability monitoring and indicating unit 12 located in the driver's cab 13. The monitoring unit 12, which may be mounted in any convenient position within the cab1 receives input from a speed sensor 14, from a potentiometer 15 which is associated with the steering column to measure the rate of steer and the angle of steer, from potentiometers 16 located adjacent the rear wheels of the tractor unit llA substantially under the turntable or fifth wheel of the articulated connection to measure relative movement between the tractor chassis and the axles, and from further potentiometers 17 located adjacent the rear wheels of the trailer llB to measure relative movement between the trailer chassis and the axles.So far as the potentiometers 16 and 17 are concerned, the principal critical movements are the relative vertical movements between the tractor or trailer chassis members and the wheel axles.

The monitoring unit 12 processes the input signals which indicate the road speed, the steering angle, the rate of steer and relative load/axle positions, comparing the signals with stored data relating to the vehicle type and characteristics.

The monitoring unit 12 generates a progressively more urgent warning of instability as a condition of instability is approached.

The generated warning may take the form of both an audible alarm and a visual readout and a facility for adjusting the warning level can be provided so that a setting can be made which will cause the driver to remain within safe limits.

As an alternative to the arrangement described above, the monitoring unit 12 can receive signals indicating relative axle loads in addition to, or instead of, the relative axle/chassis positions, for example the weight distribution as between one side of the chassis and the opposite side. The monitoring unit can also be arranged to provide a hard copy read-out to enable assessments to be made of driver behaviour.

Turning next to Figure 2, this shows a steering shaft 20 connected by a universal joint 21 to the steering box input shaft 22. The steering box input shaft 22 carries a gear wheel 23 which is coupled to a rotary potentiometer 24.

The potentiometer provides a steering input signal which is passed to a monitoring unit which compares the vehicle speed to the steering angle by means of a calibration curve.

This curve is obtained by practical tests on each vehicle type to determine the operating criteria and the band of safety tolerance to set the limits of the calibration curve.

The vehicle speed can be obtained from an output on the vehicle tachograph, speedometer or transmission pickup heads.

In practical tests, each calibration curve has been obtained and proven from wheel lift-off and vehicle instability and then re-tested with the processor set to the determined curve less 5%. This represents the safe tolerance for the audible warning and allows predictable driving control techniques to be used.

Claims

CLAIMS:

1. A stability indicating system for a road vehicle which includes means for monitoring the road speed and angle of steer of the vehicle and which provides an audible and/or visual indication in the driver's cab of an approaching condition of instability.

2. A system according to claim 1 in which the monitoring means monitors not only the angle of steer but also the rate of steer.

3. A system according to claim 1 or claim 2 in which the monitoring means additionally includes means for monitoring relative movements between the vehicle axles and the tractor, trailer or vehicle chassis.

4. A system according to claim 1 in which the warning is progressive.

5. A system according to claim 1 in which the monitoring means includes a potentiometer coupled to an element of the vehicle steering gear.

6. A system according to claim 1 in which feedback means are provided whereby, as the vehicle approaches an instability condition, the effort required to effect turning of the wheel in the direction corresponding to instability is increased.

7. A stability indicating system for a road vehicle substantially as hereinbefore described with reference to and as shown in the accompanying drawings.