Thermal insulation blankets are commonly used on exhausts, turbochargers and other heat generating elements of boats, ships, trucks, power generators and the like. The thermal insulation material comprises a layer of a thermally insulating material typically formed of mineral fibre such as ceramic fibre rock wool or fibre glass.

There are several shortcomings in this technique of thermal insulation. For example, thermal insulation blankets are typically quite fragile and easily damaged through abrasion possibly caused by vibration or incurred during maintenance of machinery. It is important that the insulating blanket maintains its shape so as to provide efficient insulation. With extended use it is known for insulation blankets to become distorted and therefore act inefficiently. Extended use, vibration and distortion of shape may lead to insulation material becoming dislodged and entering the machinery, possibly causing damage and disruption of function.

SUMMARY OF THE INVENTION The present invention provides a thermal insulation blanket in which the aforementioned inefficiencies and problems of the prior art are reduced.

In accordance with one aspect of the present invention there is provided a thermal insulation blanket comprising a

layer of thermal insulation material which i-s enclosed by a layer of woven,metal wire mesh.

In accordance with the present invention the woven metal wire mesh is pref rably attached to the layer .of insulation material in such manner that there is little movement of the woven metal wire mesh with respect to the insulation material.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a schematic sectional elevation through part of a thermal insulation blanket in accordance with the present invention; Figure 2 is a plan view of an insulation blanket in accordance with the present invention; and Figure 3 is a plan view to an enlarged scale of one corner of the insulation blanket of Figure 2 showing a woven wire mesh and stitching at edges of the blanket. DESCRIPTION OF THE INVENTION

In the accompanying drawings, there is shown a thermal insluation blanket 10. The thermal insulation blanket 10 comprises a central layer of insulation material 12 enclosed within a layer of cloth 14 as shown in Figure 1. Located externally of the layer of cloth 14 is a layer of woven stainless steel wire mesh 16 which encloses the layer of cloth 14 and the layer of insulation material 12. Figure 2 shows the layer of woven stainless steel wire mesh 16 covering the whole of one surface of the layer of the

cloth 14. The layer 16, as mentioned above encloses completely the layer of cloth 14 and the layer of insulation material 12.

Typically, the woven stainless steel wire mesh 16 is woven in an interlocking loop pattern as shown in Figure 3 although variations in the weave pattern are possible.

The thermal insulation blanket 10 has edges 18. As shown in Figure 1, the edges 18 may be formed by gathering or inturning of free edges of opposed pieces of cloth forming the layer 14 together with opposed free edges of the woven stainless steel wire mesh 16. The inturned edges of the layers 14 and 16 may project into the layer of insulation material 12 as shown in Figure 1.

The gathering or inturning of the layers of cloth and mesh results in the woven stainless steel wire mesh 16 being innermost at the edge 18 of the thermal insulation blanket

10.

Further to increase the strength of the edges 18 the gathered or doubled over portions of the layers of cloth and mesh are stitched through with fine stainless steel wire 24 as shown in Figure 1. The edge stitching is shown in more detail in Figure 3.

This combination of gathering and stitching at the edges 18 reduces the movement of the layer of woven stainless steel wire mesh 16 relative to the layer of cloth 14 and thus reduces wear on the cloth 14. This also maintains the shape of the thermal insulation blanket 10. However, the cloth and the mesh can in some instances simply be folded over at the edges 18. This method of

forming an edge 18 of the blanket 10 is convenient. However, the gathered or doubled over technique shown in Figure 1 is extremely useful where the cloth and mesh have free edges which need to be joined together to enclose the layer of thermal insulation material 12.

Also, the free edges of the cloth could be stitched separately and the woven wire mesh then wrapped around the layer of cloth 14. The free edges of the woven wire mesh could then be stitched together seperately from the cloth. As shown in Figure 1 clips 20 and hooks 22 may be used in the thermal insulation blanket 10.

The clips 20 may be used on large thermal insulation blankets 10 to augment the support given by the gathered edges 18 and to reduce further movement of the woven stainless steel wire mesh 16 relative to the cloth 14.

The hooks 22 may be used to anchor the thermal insulation blanket 10 in a working position and also help prevent movement of the woven stainless steel mesh 16. Typically, the clips 20 comprise pins 25 which pass through the full thickness of the thermal insulation, blanket 10. The pins 25 each may comprise a head 26 at one end and a hook 28 at an opposite end. To reduce fraying of the layer of mesh 16 and the cloth 14 there may also be provided a respective metal plate 29 between each of the head 26 and the hook 28 and the body of the blanket 10.

Further, depending upon the desired shape of the structure to be insulated, several individual sections of thermal insulation blanket 10, each constructed as previously described, may be joined by stitching with stainless steel

wire .

Still further, the thermal insulation blanket 10 shown in

Figures 1 to 3 does not tend to lose its shape or cause excessive wear on the layer of cloth 14 or the underlying insulation material 12 thereby maintaining its insulating properties at a maximum.

As an alternative to stitching of the edges 18, the edges

18 could be stapled.

Modifications and variations such as would be apparent to a skilled addressee are deemed within the scope of the present invention.