Field of the Invention

The present invention relates to a road gritting system for road vehicles for use in response to icy conditions.

Background to the Invention

The presence of ice or snow on roads represents one of the greatest natural hazards to road vehicles. Irrespective of any advanced road holding characteristics of the vehicle and its tyres ,or skill of the driver, when the wheels of a road vehicle come into contact with ice or snow at anything other than crawling pace the grip between the road wheels and the road is frequently lost, albeit only temporarily in some cases, but potentially with dire consequences. To those who have experienced spins on black ice in winter the feeling of helplessness can be quite traumatic.

Currently existing measures to minimise the risk of accidents during icy conditions are woefully inadequate. These include meteorological reports to drivers via broadcasting media and road-side or in-car temperature gauges to warn of the likelihood of ice formation to enable drivers to reduce their speed accordingly.

Where ice and snow exist already upon road surfaces , or it is strongly predicted, many councils throughout the UK provide a service of gritting the major roadways with sand, salt or other gritty paniculate materials (which will hereinafter be referred to as grit). This improves frictional grip between

the road tyres and the ice or snow-covered road surface in addition to lowering the freezing point of the ice or snow, accelerating melting of the ice or snow under the passage of the wheels of following vehicles.

The conventional road gritting vehicles are generally trucks, each having a distributor chute to scatter the grit over the full width of the road surface behind the truck as it travels along. This system is, however, only of limited effectiveness. The patchy distribution of the fallen grit, the inevitable delays in its laying and the limitations on the number and nature of roads that can be so treated are all profound drawbacks of the existing system.

It is a general objective of the present invention to provide a system to overcome these drawbacks and provide far greater security to the driver irrespective of where he may be when he encounters ice or snow on the roadway.

Summary of the Invention

According to a first aspect of the present invention there is provided a road gritting system for road vehicles which comprises:

One or more grit containers adapted to be fitted to a vehicle; and a respective delivery line extending from the or each grit container each line adapted to deliver the grit directly into the path of a respective road wheel or closely mounted group of road wheels of the vehicle, in use.

Preferably the system is provided with a pneumatic pump, which is suitably a compressor, to pump the grit from the grit container.

Advantageously each delivery pipe which delivers grit into the path of a road wheel which is steered as the vehicle is driven is also steerable so that it may remain in the path of the respective steered road wheel. Most suitably the delivery pipe tracks the central treads of the wheel's tyre.

Preferably the system further comprises an activating mechanism which is

adapted to open an outlet valve of the grit container and/or switch on said pneumatic pump, where such a pump is provided, to enable delivery of the grit from the grit container via the delivery pipes automatically when the vehicle's brakes are applied. This mechanism suitably also is adapted to enable delivery of the grit to the road surface before the operation of the brakes takes effect.

In a particularly preferred configuration the system comprises one grit box over each road wheel or each closely mounted group of road wheels.

Preferably the or each grit container has a gravity fed delivery outlet in addition to a pumped delivery outlet. The gravity fed delivery outlet may have a delivery metering device. Such device may be rotary and operated by a transmission shaft linked to a transmission shaft or axle of the vehicle.

According to a second aspect of the present invention there is provided a vehicle to which a system of the first aspect of the present invention has been fitted.

Brief Description of the Drawings

A preferred embodiment of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, wherein:

Figure 1 is a schematic plan view of the road wheels and transmission of a rear wheel drive vehicle to which the preferred embodiment of road gritting system has been fitted; and

Figure 2 is a side elevation view of that part of the system fitted over the right hand rear wheel of the vehicle shown in figure 1.

Description of the Preferred Embodiment

Referring to figure 1, this illustrates certain primary components of a motor vehicle, include the engine 1, the drive shaft 2 and rear wheel axles 3, in addition to all four road wheels 4a-d.

Atop the road wheels 4a-d and transmission 1,2,3 of the vehicle is mounted the gritting system which comprises a set of 4 grit-storing containers 5a-d each mounted above a respective road wheel 4a-d. Each container 5a-d has a delivery outlet 6a-d.

A compressor 7 forms part of the gritting system and serves to provide a high rate of forced grit delivery when required and is also of use in cleaning out the system.

The compressor 7 has a pressure outlet manifold comprising a plurality of pressure supply pipes 8 each of which extends to the rear end of one of the grit storage containers 5a-d and is fitted to a respective inlet nozzle 9a-d of each respective container 5a-d. As illustrated in figure 2, this inlet nozzte.9a- d is provided at the upper end of the container 5b on a level with the outlet noz l 6a-d to enable the air flow from the compressor 7 to pick up grit from the surface of the stored supply to thereby transfer it out through the outlet 6b and into a delivery pipe 10 b.

The delivery pipe 10 extends downwardly toward the wheel over which the container 5 is mounted and joins at a juncture 14 with a further delivery pipe which extends downwardly from a gravitational outlet 11 in the base of the container 5b . The portion 12 of the delivery pipe 10 below the juncture 14 terminates in an outlet portion 13 which is directed toward the wheel 4b. This outlet portion 13 may be coupled to the lower end of the delivery pipe 12 such as to swivel in order to track the movement of the wheel 4b as it is steered. A mechanical linkage may be provided between outlet portion 13 and the wheel 4b or other structures which move with the wheel 4b to achieve this.

With respect to the gravitational outlet 11, this is provided with an outlet valve 21 and a metering device 15 to control the rate of gravitation flow there-

from. The metering device 15 comprises an operatively rotating wheel 15 having radial apertures through which the grit may fall to exit through the outlet 11. The metering device and outlet valve 21 may, however, be one and the same item.

The wheel 15 is rotated by a transmission shaft 20 selectively disengagably linked to the wheel axle 3 via a gear box 18 on the axle. A universal joint 16 and a longitudinal sliding spline joint 17 are provided to allow for relative movement of the vehicle's suspension when the gritting system is mounted to the chassis of the vehicle.

By fitting the gritting system to the chassis of the vehicle, rather than to the suspension,use of rigid steel, or other metal/alloy, ducts rather than flexible rubber or plastic tubes for the pressure supply pipes 8, and much if not all of the delivery pipe 10,is made particularly practical.

It is envisaged that the system of the present invention will be factory-fitted to vehicles ranging across the spectrum from large commercial lorries or trucks down to the smallest of private cars. In those countries of the world where icy conditions are present the enhancement in safety provided by this system merits its fitment as a standard facility. Notwithstanding this, for many designs of vehicle the system may be implemented without great difficulty as a post-production upgrade.

Operation of the system begins with the filling of the grit containers 5a-d with grit in a dry friable condition through a suitable opening provided in the container 5a-d. As illustrated in figure 2, each container 5a-d may be fitted with a removable lid 19 for this purpose. It is, however, important that the lid 19 has a substantially air-tight seal to facilitate the pumped delivery of grit when the system is operational.

In order that a ready supply of grit is available for use wherever the driver may happen to be it is appropriate that stores be provided at regular intervals along roadways. However, it is intended that through efficient economical usage of the system the capacity of the grit containers carried by the vehicle

will be sufficient for several long distance journeys in winter.

Prior to setting out on a journey during icy winter conditions the driver should check that he has adequate grit supplies just as he would check, for example, the water supply in his windscreen wipers and the oil in his engine.

Where the gritting system is provided with manual switch control of heating elements in the grit containers to ensure that the grit is kept in a friable condition this heating system should be switched on either prior to or shortly after beginning the journey.

While driving along and when recognising ice or snow upon the roadway the driver should activate the delivery of grit from the gritting system, releasing grit from the base of the grit containers 5a-d through the gravitational outlets 11 by opening of the valves 21. The icy conditions are particularly serious and an instantaneous thick blast of grit upon the road surface is required then the compressor 7 should be activated also.

It is particularly important that the grit is sufficiently friable that it may be lifted by the through flowing air and forced down through the delivery pipe 10. Accordingly, it may be appropriate to heat the air passing from the compressor into the containers 5a-d by a special electrical heater or through use of air heated by the car's engine.

Activation control of the system is most suitably effected through use of electrical switching provided on the vehicle's dashboard.

For rapid response to braking under icy conditions the system may be automatically responsive to implementation of the brake levers or pedals to effect delivery of grit into the paths of the wheels 4a-d prior to the brakes taking full effect.

Where an automatic activation system is provided in response to braking of the vehicle a primer switch should be provided to give the driver overall on- off control of the gritting system.

For maximum operational control of the rate of output of grit a switching system to control the operation of the metering device 15 and gravitational outlet valve 21 may be provided. This system may also control the operational output of the compressor 7.

The system may also be temperature-responsive to activate the heaters and/or the priming for grit delivery in response to brakes actuation.

From the above it will be appreciated that the present invention has significant potential to greatly improve the standards of vehicle safety under wintery conditions. Although the invention has been described with primarily with respect to one preferred embodiment numerous alternative embodiments are conceivable within the scope thereof.

It will also be appreciated that the system is adapted to any road going vehicle with appropriate adjustments in capacity in shape and configuration of the elements of the system.