GB2353939A

GB2353939A - An aerodynamic safety helmet

Info

Publication number: GB2353939A
Application number: GB9921596A
Authority: GB
Inventors: Rodney Aston Lee
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-09-13
Filing date: 1999-09-13
Publication date: 2001-03-14
Also published as: GB9921596D0

Abstract

The invention relates to a safety helmet (1) for use in applications where the wearer is exposed to the air through which he or she is travelling. The safety helmet has an exterior surface which is provided with a plurality of depressions (4) such that the exterior surface has a "dimpled<SP>"</SP> effect. The depressions have the effect of reducing drag over the surface of the helmet making it quieter and more comfortable for the user to wear and increasing efficiency due to a better aerodynamic performance. The size and shape of each depression may vary over the surface of the helmet, and the properties of the depressions may vary according to their location on the helmet. One or more areas of the helmet (2, the visor, and 3, the visor hinge cover) may be substantially free of depressions.

Description

2353939 707G7.348 Safety Helmet The present invention relates to a safety

helmet, and in particular to a safety helmet which may be used in applications where the wearer is exposed to the air through which he or she is travelling, rather than, for example, being enclosed inside a vehicle. Such applications include those in which the wearer is on a motorcycle, in a racing car or other motorsport vehicle, or participating in water sports (e.g. power boat racing), parachuting or skydiving.

A particular problem encountered with safety helmets which are worn in such applications is that, at least at higher speeds, wind resistance experienced by the wearer can become particularly noticeable. Wind resistance will of course increase with increasing speed, and coupled with this increasing wind resistance is an increase in wind noise experienced by the wearer inside the helmet. It would be advantageous to reduce wind resistance, and thereby also the associated wind noise.

In accordance with the invention, there is provided a safety helmet in which at least part of the exterior surface is provided with a plurality of depressions, such that the exterior surface has a "dimpled" effect.

The depressions have the effect of creating turbulence adjacent the surface of the helmet, such that the flow of air in this area becomes nonlaminar. Non- laminar flow around an object causes less drag than laminar flow, because the area of turbulence immediately behind the object is reduced. Hence, in the present invention, drag on the helmet is reduced which also causes a resultant reduction in wind noise experienced by the wearer. This increases the overall comfort for the wearer, as there will be less strain on the wearer's neck muscles and the environment inside the helmet will be quieter. In a motorsport environment, less drag will have the advantages of improved fuel economy and/or performance.

The depressions may be any suitable size such that the effect of reducing drag is produced. Preferably, the depressions are small in width and/or depth in relation to the size of the helmet such that the overall profile of the helmet were it not to have the depressions is retained. Preferably, the maximum width dimension of each depression is less than 5cm. A more preferable maximum dimension is less than 2cm, and a maximum dimension of less than 1cm is still more preferable. In addition, the depressions should not be so small that the effect of reducing drag is not present or is negligible. Therefore, the minimum width dimension of each depression is preferably greater than imm, more preferably greater than 2mm, and still more preferably greater than 5mm. The width dimension of each depression preferably ranges between Imm and 2cm, and more preferably between imm and 1cm.

Preferably, the maximum depth dimension of each depression is less than 1cm, and more preferably less than 5mm. However, the depth dimension is also preferably greater than 0.5mm, and more preferably greater than 1mm.

The depressions may be any suitable shape in plan view, such as polygonal or oval, regular or non-regular, but the depressions are preferably circular. The depressions may have any suitable profile when viewed in cross-section, which may be regular or non-regular. Preferably, the depressions have a concave profile which increases in depth from the edge of the depression towards the centre.

The size and shape of each depression may be uniform over the surface of the helmet. Alternatively, the size and shape may vary. For example, some depressions may be larger and/or have a deeper profile in some locations than depressions in other locations.

The properties (e.g. size and depth) of the depressions may vary according to their location on the helmet, in order to tailor their effect on the air flow over the helmet surface, and some areas of the helmet may be substantially free of depressions. The depressions may be provided only in those areas of the surface where the effect is required. For example, the generally forward-facing surfaces may be substantially free of depressions. The depressions may be provided only in those areas of the helmet which lie substantially parallel with or within a certain number of degrees from parallel (e.g. 45 degrees or less, or 30 degrees or less) with the direction of travel of the helmet through the air flow. The depressions may not be necessary on the generally rearward-facing surfaces.

The size, location and/or absence of depressions in areas across the surface of the helmet may vary according to the specific use of the helmet. In some applications (e.g. motorcycle or motor-racing helmets), the orientation of the helmet when travelling through the air will remain substantially the same when travelling at speed, and therefore the depression properties can be adjusted across the surface accordingly. In other applications, it may not be possible to retain the helmet in a fixed orientation relative to the direction of travel (e.g. skydiving), and therefore more uniform depression characteristics across the entire surface of the helmet may be appropriate.

In the case where the helmet is provided with a visor, the visor is preferably free of depressions.

This is in order not to restrict or distort the wearer's view.

The helmet can be made of the same material as it would normally be made for the particular application for which it is designed. The depressions can be provided in the helmet mould, or they may be formed in the helmet surface after moulding, e.g. by mechanical means or by applying a coating. The relevant safety requirements or standards, if applicable, would still need to be met, of course.

An embodiment of the invention will now be described by way of example only, with reference to the accompanying Figure which shows a motorcycle helmet or "crash helmet" in accordance with the invention.

The helmet 1 includes a visor 2 and a visor hinge cover 3. The helmet is provided with a plurality of relatively small, circular depressions 4 over the entire surface of the helmet 1, including the visor hinge cover 3, with the exception of the visor 2. For ease of representation, the depressions are shown only in part in the Figure.

The overall dimensions of the helmet will vary according to the size of the user's head. The dimensions of the circular depressions 4 may be within the values and ranges discussed above.

Claims

Claims:

1. A safety helmet in which at least part of the exterior surface is provided with a plurality of depressions.

2. A safety helmet in accordance with claim 1, wherein the depressions are small in relation to the size of the helmet.

3. A safety helmet in accordance with claim 1 or 2, wherein the maximum width dimension of each depression is less than Scm.

4. A safety helmet in accordance with claim 3, wherein the maximum width dimension of each depression is less than 2cm.

5. A safety helmet in accordance with claim 4, wherein the maximum width dimension of each depression is less than 1cm.

6. A safety helmet in accordance with claim 1 or 2, wherein the maximum width dimension of each depression is between 1mm and 2cm.

7. A safety helmet in accordance with claim 6, wherein the maximum width dimension of each depression is between 1mm and 1cm.

8. A safety helmet in accordance with any preceding claim, wherein the maximum depth dimension of each depression is less than 1cm.

9. A safety helmet in accordance claim 8, wherein the maximum depth dimension of each depression is less than 5mm.

10. A safety helmet in accordance with any preceding claim, wherein the maximum depth dimension of each depression is greater than 0.5mm.

11. A safety helmet in accordance with claim 10, wherein the maximum depth dimension of each depression is greater than Imm.

12. A safety helmet in accordance with any preceding claim, wherein the depressions are circular.

13. A safety helmet in accordance with any preceding claim, wherein the depressions have a concave profile.

14. A safety helmet in accordance with any preceding claim, wherein the size and shape of each depression is uniform over the surface of the helmet.

15. A safety helmet in accordance with any of claims 1 to 13, wherein the size and shape of each depression varies over the surface of the helmet.

16. A safety helmet in accordance with claim 15, wherein the properties of the depressions vary according to their location on the helmet.

17. A safety helmet in accordance with claim 15 or 16, wherein one or more areas of the helmet are substantially free of depressions.

18. A safety helmet in accordance with claim 17, wherein the one or more areas free of depressions are provided on the forward-facing surface of the helmet when in use.

19. A safety helmet in accordance with claim 17 or 18, wherein the helmet is provided with a visor which is 7 free of depressions.

20. A safety helmet in accordance with any of claims 15 to 19, wherein the depressions are provided only in those surface areas of the helmet whose tangents are at 45 degrees or less to a direction parallel with the direction of travel of the helmet through the air flow when in use.

21. A safety helmet in accordance with claim 20, wherein the depressions are provided only in those surface areas of the helmet whose tangents are substantially parallel with the direction of travel of the helmet through the air flow when in use. 15

22. A safety helmet substantially as hereinbefore described with reference to the accompanying drawing.