GB2266989A - Cooling magnetrons - Google Patents

Abstract

A magnetron includes an outer casing comprising a metal casting having an integrally formed cooling fin arrangement 2, 3. Preferably, as shown, the casing is formed in two halves 2, 3 between which is sandwiched the vacuum casing 1 of the magnetron. The casing, e.g. formed from an alloy of aluminium, has apertures allowing access for high tension leads 7 and for allowing protrusion of the output probe 4. <IMAGE>

Description

MAGNETRON The invention relates to a magnetron having a cooling fin arrangement.

Known magnetrons, for example of the type used within microwave cookers, include an outer casing formed from one or more sheets of metal bent and folded together about the vacuum envelope of the magnetron. A plurality of cooling fins each stamped from further sheets of metal are folded to an appropriate shape and stacked together within the outer casing about the vacuum envelope. The capital cost of appropriate stamping and folding machinery is high. Such an arrangement can only be provided at economic cost if production levels are also high.

This invention provides a magnetron including an outer casing comprising a metal casting having an integrally formed cooling fin arrangement.

Because the outer casing comprises a metal casting having an integral cooling fin arrangement, assembly can be much less complicated, and a magnetron according to the invention is therefore appropriate for small production runs, or where the need to minimise capital expenditure is important.

In a preferred embodiment the outer casing comprises two parts sandwiched together about the vacuum envelope of the magnetron.

In order that the invention may be well understood, an embodiment thereof will now be described by way of example with reference to the accompanying diagrammatic drawings, in which; Figure 1 is a plan view from one side of a magnetron within an outer casing according to the invention; Figure 2 is a view along the direction of arrows X-X showing the mating face of one of the casing parts of the magnetron shown in Figure 1; Figure 3 is a cross sectional view along line Y-Y of Figure 2; and Figure 4 is a cross sectional view along line Z-Z of Figure 2.

A magnetron, for use with a microwave cooker, comprises a vacuum envelope 1 sandwiched between a pair of mating casing parts 2, 3. The vacuum envelope 1 for the magnetron may be of generally known type and is not illustrated in detail. Conventionally such an envelope comprises a cylindrical anode structure having a plurality of internal circumferentially spaced resonant cavities and a coaxial cathode structure. The cylindrical anode is placed within a magnetic field at right angles to the electric field between the cathode and anode. As shown in Figure 1, the envelope includes an output probe 4 which extends from the casing 2, 3.

According to the invention, the casing comprises a pair of metal castings 2 and 3 formed from an alloy of aluminum. Since the two parts are mirror images of one another, only housing part 2 is shown in Figures 2, 3 and 4.

Each housing part includes an uppermost, as shown, compartment 5 having an entrance 6 into which high tension leads 7 (Figure 1) pass to supply power to the magnetron.

The compartment 5 serves to shield the high tension parts against tampering and the emission of electromagnetic radiation. A cavity 8 of semi-cylindrical shape is located beneath the uppermost compartment 5 so that the two housing parts can sandwich tightly above the generally cylindrical anode of the vacuum envelope to ensure that excess heat can be efficiently conducted away from the anode through the walls of the cavity 8. An opening 9 is located beneath the cavity 8 to receive the output probe 4. Four integrally formed generally planar cooling fins 10 disposed one above the other are located about the casing. A generally planar base portion 11 includes through holes 12 to mount the magnetron against another structure, for example a waveguide located within a microwave cooker. The two casing parts 2, 3 may be connected together by bolts or screws, or alternatively by means of adhesive or the like.

In alternative embodiments, the housing may be formed in one piece, or may include openings to allow ventilation to the vacuum envelope. The number of cooling fins may of course be varied and other metals used to form the casting.

Claims (5)

1. A magnetron including an outer casing comprising a metal casting having an integrally formed cooling fin arrangement.

2. A magnetron, according to claim 1, in which the arrangement comprises a plurality of fins disposed one above the other.

3. A magnetron, according to claim 1 or claim 2, in which the outer casing comprises two parts sandwiched together about the vacuum envelope of the magnetron.

4. A magnetron, according to any preceding claim, in which the metal is an alloy of aluminum.

5. A magnetron including an outer casing substantially as described with reference to any one of the drawings.