GB2493523A - Heat dissipation for lamp headsets - Google Patents

Abstract

A modification to plastic mining lamp headsets to improve heat dissipation consists of stripping a lamp headset (a) to a bare shell, rebating the rear of the lamp where the original helmet bracket (e) fits, and drilling out and tapping the existing charging keyway aperture at the rear of the lamp. A threaded plug (b) of heat conducting material is screwed into the aperture, and its rear machined flush to accept a finned external heat sink (c) that is retained in position by the helmet bracket (e). A heat sink plate (d) is attached to the end of the plug (b) and is used to mount LEDs. The heat generated by the LEDs is conducted to the heat sink (c) and dissipated. The modification provides a lamp capable of handling powerful LEDs which is suitable for recreational caving, cycling, exploring and potholing.

Description

A heat conduction and dissipation system This invention is a system of modification or manufacture of plastic mining lamp headsets which addresses the issue of the heat generated by high power Light Emitting Diodes (LED5).

In the early part of the 20t1i century electric cap lamps (often referred to as "Pit Lamps") were developed for mining purposes, originally of metal, later versions where made of bakelite, and then later still plastic Since the 1960s the design has remained basically unchanged and has been extensively copied mostly by manufacturers in China and the Far East.

As well as commercial mining, these lamps have proven popular for recreational activities such as the exploration of abandoned mine workings, caving, potholing, and other adventure sports.

Although of proven reliability the plastic construction is highly unsuitable for use with high power LED emitters that generate a lot of heat. This is due to the very poor thermal conductivity of plastic. The latest high powered LEDs generate a very high degree of heat when driven at full power. This modification overcomes this issue in a very neat manner that is highly suitable for either mass conversion of existing lamp headset shells or complete manufacture in the described modified form with very little change to existing moulds etc. It will also enable effective recycling of mining equipment that is rapidly becoming obsolete and would probably become scrap into a comparatively low cost but very high powered useful cycling lamp or underground lamp for the hobby caving enthusiast.

A feature of the original lamp design is the ability to recharge the battery through a keyway incorporated into the rear of the headset, this feature is unimportant for recreational use where batteries can be detachable and charged separately. However, the modification process converts this aperture into a convenient means of fitting a heat conductor.

The modification involves the following steps. Measurements are relative to the Oldham GT cap lamp but the procedure can be applied to any plastic cap lamp headset.

This invention includes only 4 components shown in Figure 1 of the accompanying drawing, the modified lamp headset (a), the "Heat Conductor" (b) the "Heatsink Bridge" (c) and LED mounting plate (d). The bracket (e) is an original component.

The headset being modified should be in the form of a bare shell, and assembled with other component parts after conversion. An unmodified shell is shown in the accompanying drawing as Figure 2 The upper rear of the lamp headset shell is rebated in the area where the helmet attachment bracket fits to a depth equal to the thickness of the "Heatsink Bridge" (described in c below) and a typical length of 30 millimetres, so as to allow the fitting of the Heatsink Bridge flush with the rear of the lamp. 3.

The rear charging keyway aperture is drilled out to a suitable size so as to encompass the complete diameter of the charging hole, (Typically 13 millimetres.); this aperture should pass right through into the lamp. 4.

The aperture created is tapped with a screw thread to a suitable size (Typically 16 millimetres). The modified shell is shown in Figure 1 (a) in the accompanying drawi ag 5.

The "Heat Conductor" (described in b below) is coated with a suitable silicone based compound so as to ensure watertight integrity, and screw fitted to a depth where the outer edge abuts the body of the lamp and the machined flat is presented parallel to the face of the lamp. 6.

The outer end of the heat conductor is machined flush with the rebated surface of the lamp body so as allow the fitting of the Heat Sink Bridge (sec c below) and helmet bracket (original part, Figure 1 (e) in accompanying drawing) which retains it in position.

The above steps complete the modification of the headset (Figure 1(a) in accompanying drawing) which can be reassembled with original parts plus a plate typically of copper or aluminium attached to the aforementioned heat conductor with suitable screws and used to mount the LEDs. (Figure 1 (d) in accompanying drawing) Heat generated by the LEDs will pass through the mounting plate and be rapidly conducted through the heat conductor to the external heat sinks and so dissipated into the atmosphere.

b. (b in Figure 1 of accompanying drawing) The Heat Conductor shown in Figure 1(b) in the accompanying drawing This consists of a length of heat conductive material such as aluminium bar of suitable diameter (Typically 16 millimetres) cut to a suitable length (Typically 35 millimetres) and screw threaded to the same size as the threaded aperture created in the back of the lamp body. As this enters the lamp at an angle its inner end has an angled flat face which is presented parallel to the front of the lamp when fitted.

c. (c in Figure 1 of accompanying drawing) The "1-leatsink Bridge" an external heatsink shown in Figure 1 (c) in the accompanying drawing This is in the fonn of a strip of heat conductive material such as aluminium of typically 90 millimetres length and 30 millimetres width shaped so as to follow the contour of the top of the lamp body, and with a finned upper surface. It can be manufactured from ordinary flat aluminium sheet, bent to shape, and fitted with adhesive separate heats inks of suitable size.

The rear is shaped so as to fit into the rebate cut into the rear of the tamp headset and is retained in position by the original helmet bracket. Figure 1 (e) in accompanying thawing.

The front can be secured either by a suitable adhesive or by a small diameter screw, typically 3 millimetres passing into the body of the lamp and sealed with silicone for watertight integrity.

A lamp headset modified as above andre assembled with an LED module and original parts as required is shown as Figure 3 in the accompanying drawing.