GB2279150A - Low road friction detector for vehicles - Google Patents

Abstract

An extra, smaller vehicle roadwheel 1 is lowered, optimally by remote control, onto a surface that is suspected of being slippery, under such downward pressure of a spring 4 that the wheel rotates despite constant slight retardation applied to it. A signal to the driver's cab generated by this rotation, which alters or ceases when road friction decreases sufficiently to cause this rotation to stop (due to ice or other such causes), alerts the driver to take appropriate precautions to avoid an accident before any main roadwheel skidding due to braking commences. <IMAGE>

Description

ROAD ICE DETECTOR FOR VEICLES This invention relates to a device for warning that ice or any other loss of friction situation is present beneath a vehicle.

It is often heard said "I put on the brakes & just slid into the vehicle in front" (or other obstruction.) An accessory to cope with this has been developed that warns of 2 freezing temperature outside the vehicle. This is an improvement on nothing but does not give a definite & reliable analysis of the condition on the road surface.

The device described herein consists of an extra, smaller, roadwheel, held in contact with the road surface by force having a constant retarding force applied to it. A pulsing system initiated by a sender on the periphery of the wheel, or any other suitable system, gives an indication in the cab that the wheel is rotating. When friction with the road surface decreases or stops due to ice forming or similar conditions, the wheel ceases to rotate & the signal stops.

(or by arrangement & more quietly, the signal may be made to start when rotation stops but this is not fail-safe.) This alerts the driver at that moment that he is on a slippery surface & does not leave hitto first discover it when he brakes.

This wheel is normally retracted & only lowered to the road when adverse conditions may be expected (e.g. in the depth of winter or flooding.) It would also be sensible for this wheel to be behind & in line with an existing road wheel, so that debris in the road is flattened by it first. (e.g. drink cans.) Otherwise for appearances sake it could be mounted under a suspension unit but then ought to be guarded. It would likewise be sensible to ensure the extra wheel is retracted before reversing or mounitng curbs or the like, to prevent damage.

One possible arrangement of such a deviate will now be described.

Figure 1 shows this wheel (1) on a swinging retractable arm (2) attached to the car floor by pivot point (3) & held in contact with the road by spring (4). For simplicity, the wheel is shgwn still vertical when retracted to position (5) by Bowden cable (6) or other device, operated from the cab.

It could, however, be rotated through 90 degrees, when elevated, to lie under the floor or be withdrawn telescopically vertically & sprung vertically also.

The raising & lowering would be operated remotely from within the vehicle normally but could be set from outside before driving as a cheaper alternative.

Figure 2 shows the wheel (1) in section. A brake pad (7) runs on 2. disc (8) permanently & a system of self adjustment to ensure constant braking against wear will be necessary, such as a constant sprung pressure on the rear of the pad. Cooling blades (9) form part of the disc assembly but overheating will be reduced also by the expected ambient temperature when used in icy conditions. A pulsing device, which could for instance be a magnet fixed to the periphery of the disc, passes a sensing device each revolution (10 & ) sending this pulsed signal via cable (12) to the carts electronics system. This will, in turn, present to the driver a suitable signal to alert the driver to the fact that rotation has ceased of this special wheel due to lack of grip.

The driver can then observe caution, accordingly.

Claims (5)

1 An extra, smaller roadwheel, lowered from a vehicle, having a device applying sufficient pressure downward to ensure rotation in normal circumstances, despite constant slight retardation applied to it, this rotation generating a signal which alters or ceases when road friction decreases causing this rotation to stop, thus alerting the driver.

2 A signal system generated by the rotation of this extra roadwheel, mentioned in Claim 1, which can be heard by the driver in the cab, to alter or cease when rotation of this extra roadwheel ceases.

3 A means, swinging, scissoring or telescopic, remotely or otherwise controlled, of lowering the extra roadwheel mentioned in claim 1, under sufficient pressure to ensure constant contact with the road & hence ensure rotation of that wheel in normal circumstances. Also to allow it to retract when not required.

4 A braking system to apply to the extra roadwheel, as mentioned in claim 1, with compensation for wear to ensure constant retardation of that wheel.

5 A Road Ice Detector Eet Vehicles substantially as described herein with reference to Figures 1-2 of the accompanying drawing.