This invention relates to an air distribution system for the windscreen of a vehicle cab and in particular for the cab of an agricultural tractor or similar vehicle.

Such vehicles typically have an external windscreen wiper mounted in the middle of the windscreen and which is powered by a motor mounted on the inside of the windscreen. The most important part of the windscreen to demist and defrost is the middle part in order for the driver to have a good view of the road or field or any equipment mounted on the front of the vehicle (e.g. a front-loader).

It is known for tractor cabs to have a console arrangement either side of the steering wheel which includes vents for distributing air onto the windscreen and into the cab but such vents have previously not been good at directing air to the middle portion of the screen, especial if the wiper motor interrupts the air stream to the above mentioned windscreen area..

It is an object of the present invention to provide an air distribution system which can conveniently overcome the above problem by supplying air to this middle part of the windscreen.

Thus according to the present invention there is provided a vehicle cab windscreen air distribution system for a windscreen provided with an external windscreen wiper and a windscreen wiper motor mounted on the inside of the windscreen, the distribution system comprising an air distribution housing which at least partially surrounds the wiper motor, the housing defining a passage for the supply of air onto the inside of the windscreen in the vicinity of the motor.

Such a system ensures the supply of air to the middle part of the windscreen in a simple and compact manner. At the same time, the windscreen wiper motor is hidden.

The passage for the supply of air may be defined between a motor housing and part of the air distribution housing.

Alternatively, the passage for the supply of air may be completely defined by the air distribution housing. The present invention is particularly suitable for vehicle cabs which have windscreens can be pivoted to an open position, the motor moving into a position where it is surrounded by the air distribution housing when the windscreen is in its closed position.

The air distribution housing may also included additional outlets spaced from the motor for the discharge of air into the associated vehicle cab.

The present invention will now be described, by way of example only, with reference to the accompanying drawings in which:-

Fig. 1 shows an external perspective view of an air distribution housing in accordance with the invention;

Fig. 2 shows a front view of the housing of Figure 1 ;

Fig. 3 shows a section along line A-A of Figure 2, and

Fig. 4 shows a detail (B) of Figure 3.

Referring to the drawings, a tractor cab is provided with a two-piece windscreen 1 with an upper part 1 a and a lower part lb. A motor housing 2 encloses a wiper motor 2a and a gearing 2b which are mounted on the inside of the upper part of the windscreen l a. A wiper 5 is mounted on the outside of the upper part la of the windscreen and is driven by motor 2a and gearing 2b.

As is well known, the upper part l a of the windscreen is pivotally mounted at its upper edge on the cab so that the windscreen can be pivoted together with the wiper 5, motor 2a, gearing 2b and motor housing 2 to an open position by turning a fastening lever 6 to its open position. The upper part l a of the windscreen 1 is supported in its open position by a gas spring (not shown).

In accordance with the present invention, an air distribution housing 3 is provided which contains a lower part 4 and which partly surrounds the wiper motor housing 2 and defines a passage 3 a through which air can flow to the windscreen 1 a as shown by the arrow X in Figures 3 and 4. As can be seen this air flow exits the housing 3 via the gap 3b between the motor housing 2 and the top edge 3c of housing 3 around the pivot of the wiper and thus air is guided to the windscreen on the inside of the cab. This ensures that the air reaches the middle part of the windscreen as required. Air also exits from the lower part 4 as shown by arrow Y via outlet 9 the flow through which is controlled by flaps 8 which can be moved by the tractor driver or the air ventilating/conditioning system between the full and dotted line positions of Figures 3 and 4 to regulate air flow into the cab. Further some slots 7 may be provided in the lower part 4 of the air distribution housing which may be a separate component from the upper housing part 3 along a break line 4a to allow easy access for servicing etc.

Figure 3 also shows the upper part la of the windscreen in its open position la' in which the motor housing 2 has been moved away from the air distribution housing 3. Although in the arrangement described above, the air is directed between the outer surface of the motor housing 2 and the inside surface of the air distribution housing 3, the air passage may be define completely by the housing 3 preferably by providing a further inner surface 3d to the housing 3 as indicated in dotted detail in Figure 4. This alternative arrangement serves to shield the motor to a certain extent from the effects of the hot air which may be passed through passage 3 a.

The invention can also be used on a one-piece non-opening windscreen, where it is not necessary, to provide a quick defrosting of the middle part of the windscreen around the windscreen wiper mounting.