GB2372692A

GB2372692A - Toaster with heat shield

Info

Publication number: GB2372692A
Application number: GB0105134A
Authority: GB
Inventors: Leslie Alexander Gort-Barten
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-03-01
Filing date: 2001-03-01
Publication date: 2002-09-04
Anticipated expiration: 2021-03-01
Also published as: GB2372692B; GB0105134D0

Abstract

A cooking appliance comprises a toaster including a centrally disposed cooking section having a frame supporting one or more heating elements, and a cover 2 to enclose said heating elements, the cover having slots to enable slices of bread to be placed in the heating section, at least one end cover 6, 7 at one end of the cooking section 1, and an end wall 14 disposed between the cooking section 1 and the end cover 6, 7 to reduce the amount of heat from the heating element or elements which is transmitted to the end cover, the end wall 14 being enclosed by said end cover 6, 7. The end wall 14 has sufficient mass to form a heat sink, and acts as a heat shield to reduce the amount of heat reaching the end cover 6,7.

Description

A cooking appliance This invention relates to a cooking appliance, particularly but not exclusively, an electric toaster.

A known type of upright electric toaster is illustrated in Figure 1 of the accompanying drawings.

The toaster has a centrally disposed cooking section 1. The toaster has a frame (not shown) enclosed by a cover 2 which has two parallel slots 3 in its upper side for receiving slices of bread for toasting purposes. A pair of planar heating elements (not shown) disposed in spaced parallel relationship are located on opposite sides of each slot. At the base of each slot there is a support member, the two support members being connected together and being pivotally mounted on the frame. The support members are connected to an external lever 4 by which the support members can be manually moved between a lower position, in which a slice of bread is fully located within each slot so as to be aligned with the heating elements, and a raised position in which a slice of toast in the slot is raised above the top surface of the toaster to enable it to be removed by hand. A removable crumb tray 5 is located in the lower part of the cooking section 1 the tray being slidable out of the bottom of the frame for cleaning purposes. The tray catches crumbs and other extraneous matter from the bread or similar matter being toasted.

The cooking section 1 of the toaster is closed at its ends by end cover 6,7 which are secured by screws to the main frame. In the final stage of assembly, the cover 2 is placed over the centre section where is overlies respective peripheral flanges on the two end casings 6,7 to which it is secured by screws. The peripheral flanges are inset with reference to the outer profile of the end casings to provide an abutment against which the edge of the cover 2 abuts. Because the cover 2 is made of stainless steel sheet, it's edges tend to be sharp and to avoid any risk of the user hurting themselves, it is necessary for the cover 2 to be slightly recessed below the outer profile of the end cover 6,7. The end casings are formed of a light metal alloy, typically an aluminium alloy, diecasting which is polished after casting to have a smooth aesthetically desirable external surface.

Since a considerable amount of heat is generated during the toasting process, the cooking section includes a heat shield (not shown) made of a thin sheet of steel located between the outermost heating element and the end casings.

The present invention seeks to provide an improved toaster of this type and, in particular, an improved design which increases the efficiency of manufacturing the toaster.

According to the present invention there is provided a cooking appliance including a centrally disposed cooking section having a frame supporting one or more heating elements, and a cover to enclose said heating elements, the cover having access means to enable items to be cooked to be placed in the heating section, at least one end cover at one end of the cooking section, and means to reduce the amount of heat from the heating element or elements which is transmitted to the end cover, characterised in that said one end of the cooking section is closed by an end wall, the end wall being enclosed by said end cover, said end wall forming a heat shield to reduce the amount of heat reaching the end cover.

Preferably, a said end wall is located at each end of the cooking section and each end wall being of sufficient mass to form a heat sink, and is preferably formed of a light metal diecasting.

In a preferred embodiment, an inner peripheral face of the or each end cover overlies a peripheral flange on the associated end wall, said end wall having a further peripheral face against which said cooking section cover abuts to form, on the outer surface, a smooth transition between the cooking section cover and the end cover. In this case, the peripheral flange may have a plurality of protuberances spaced about the periphery against which the inner peripheral face on the end cover abuts.

The end cover or covers may be formed of a light metal diecasting or of a plastics material, and may be secured to the end wall by a snap connection.

The present invention also provides a method of manufacturing an end cover for an appliance wherein the or each end cover is formed by diecasting in a two part mould, the end cover (s) having a planar end face adapted to abut another face or edge of the appliance, the parting line between the two parts of the mould being adjacent said planar end face.

A preferred embodiment of the present invention will now be described by way of example with reference to the accompanying drawings in which : Figure 1 shows a general view of the known toaster, and Figure 1 b shows a sectional profile of the end cover in greater detail, Figure 2 shows a general view of a toaster according to the present invention with two slots, Figure 3 shows a plan view of the toaster according to Figure 2, Figures 4a, 4b and 4c show respectively outer and inner perspective views and a sectional view of an end cover, Figure 5 shows a side view of an end cover incorporating a control switch assembled to an end wall of the cooking section, Figures 6a and 6b show respectively a perspective view and a side view of an end wall of the toaster cooking section, Figure 7 shows a part sectional top view of the end cover illustrated in Figures 5a and 5b showing details of the location of the cover as secured to the end wall of the toaster, Figure 8 shows in greater detail the connection illustrated in Figures 7a and 7b.

Referring now to Figure 1 and Figure lb, Figure lb shows a sectional view of part of the end cover at its junction with the cover 2 of the heating section. As described earlier, the cover 2 of the cooking section is screwed to the flange of the end covers 6,7, the depth of the flange shoulder being such that the edge of the cover lies slightly below the outer surface of the end cover 7 to completely shield the edge of the heating section cover 2.

The end covers 6,7 of this known toaster are formed of a light metal alloy diecasting using a split mould technique having a two-part mould in which the two parts of the mould are brought together linearly to define the shape of the finished article. Molten metal is then poured or injected under pressure into the mould. After the molten metal has set the two parts of the mould are moved linearly apart to enable the cast component to be released.

Since the two parts are moved linearly apart it is not possible to have undercuts in either part of the component as otherwise it would not be possible to withdraw them from the mould. In fact each face of the component which abuts the mould must have a draught line of typically 1 . Inevitably, this means that at one point on the end cover the profile is defined by one mould part on one side and by the other mould part on the other, the split line or parting line between the two mould parts being shown as line X. This parting line is determined by the desired outer profile of the component, subject to the limitations of mould design and the necessity to provide the required draught lines. It is again inherent in the moulding process that there are slight gaps between the two mould parts which means that metal pours into this gap to form what is known as flashing. This flashing extends out along the parting line and must be removed afterwards by grinding and polishing. Thus, this flashing lies on the outermost surface of the end cover, which is visible on the finished article. It is a characteristic of cast light alloy metals that they contain a large number of voids caused by gas bubbles during the casting process and there tends to be a concentration of these gas bubbles in the region of the parting line, although the outer surface is generally smooth and pit-free. However, when the flashing is removed and the outer surface is ground and polished there is a significant risk of pinholes appearing in the outer surface as a result of the exposure of these normally internal voids. These pinholes render the product unacceptable to the final consumer and therefore any components having such pinholes have to be scrapped. The percentage of products which have to be scrapped for this reason adds significantly to manufacturing costs. The present invention seeks to provide a solution to this problem.

The present invention also seeks to provide a new construction of the toaster which minimises the transmission of heat from the cooking section to the end casings to facilitate the use of materials for the end covers which are more sensitive to heat than cast alloy but which have other desirable qualities such as low cost.

Referring now to Figures 2 and 3, of the accompanying drawings, there is shown an embodiment of the present invention corresponding to the known toaster as illustrated in Figure 1. Like references refer to like parts. The toaster is a two slice toaster having two parallel slots 3 formed in a cover 2, which encloses the centrally disposed cooking section 1.

The cover 2 is formed of stainless steel sheet. The cooking section 1 is covered at each end of the toaster by a respective end cover 6 and 7. The end cover 7 is larger than the end cover 6 to enable it to accommodate switch and timer controls for the toaster.

Referring now to Figures 4a, 4b and 4c, there is shown the left-hand end cover as viewed in the drawings of a first embodiment of the present invention. The end cover consists of a one-piece casting of a light metal, typically aluminium, alloy and has a curved outer end wall 8 having cast therein a plurality of shallow grooves 9 arranged in spaced parallel relationship. Although not shown in this embodiment, it is possible for some or all of the grooves to be open slots to enable air to flow through the interior of the cover. The end wall 8 extends into a side wall 10 extending away from the end wall 8 to a planar joining line or face 11 by which the end cover 7 is adapted to fit over and abut an end wall of the cooking section 1. As shown in cross-section in Figure 4c, the end cover is designed to be cast in a two-part mould in which the two parts are drawn laterally apart in the direction of the arrows A to enable the component to be released from the mould, the parting line being in the plane of the end face 11. To achieve this the outer profile of the end cover is formed in one mould half and the inner face of the cover by the other mould part, the inner and outer profiles of the cover being designed with the necessary draught lines to enable this to be done. The result of this form of construction is that the parting line between the two mould parts and hence the flashing lies on the end face of the cover which, in the fully assembled toaster abuts the edge of the cooking section cover 2. As can be seen in Figures 4b and 4c, the end cover has cast integrally therewith two bosses 12 for receiving self-tapping screws by which the cover is secured to an end wall of the cooking section. The end cover 7 has web like stiffening ribs 13 which are cast integrally in the cover. There are four such ribs disposed around the upper parts of the cover and one on each side towards the lower end of the cover. At its lower side, the end wall has two recesses adapted to locate around feet on the main frame of the toaster.

Turning now to Figure 6a and Figure 6b, there is shown respectively a perspective view and a side view of an end wall 14 of the cooking section of the toaster. The end wall 14 is formed of cast light alloy, preferably aluminium, again using a two-part moulding. On its lower side, the wall has two feet 16 by which the wall is secured to the main frame (not shown) of the toaster. Adjacent its vertical centre line, the end wall has two bosses 15 adapted to receive screws by which the adjacent end cover 7 can be secured to the end wall 14, the bosses 15 being aligned with the bosses 12 on the end cover 7.

As illustrated in Figure 7, and in the scrap view of Figure 8, the outer profile of the end wall is stepped having an outer peripheral face 17 and a lower peripheral face 18 with a shoulder 19 formed at the junction of the two faces 17,18. The lower peripheral part 18 has a plurality of protuberances 20 spaced along its length and extending outwardly proud of the surface of the face 17. The end cover 7 is adapted to locate on these protuberances 20 and when fastened to the end wall by the screws, is drawn up close to abut the shoulder 19 between the two stepped parts of the periphery. In this way, contact between the end cover 7 and the wall 14 is kept to a minimum which reduces the transmission of heat from the end wall 14 into the outer cover 7. As mentioned previously, this feature facilitates the use of materials, such as plastics, for the end covers which are less heat-resistant that the aluminium casting. The scrap view shown in figure 8 illustrates an alternative form of construction of the end cover made from a plastics material. This embodiment has additional stiffening ribs 21 which in the assembled condition, have a tongue 22 which abuts a web 23 on the end wall 14 to prevent the plastic end cover from splaying out if for example, its fastening screws are fastened too tight.

As shown also in Figure 5, the outer peripheral part 17 of the stepped periphery is adapted to receive the cover 2 of the cooking section which is secured to this periphery by means of screws 24. When so fastened, the cover 2 abuts the end face 11 of the end cover which stands proud of the periphery 17 of the end wall. In this way, a smooth outer periphery for the toaster is obtained which not only provides an aesthetically pleasing appearance but facilitates cleaning of the appliance.

It has been found that by forming the end wall as a diecasting, the wall forms a substantial barrier to the transmission of heat and also forms a heat sink. The result is that far less heat is transmitted to the end covers. This has the advantage that the slots previously provided for ventilation are no longer essential which greatly increases the design freedom for the end covers in terms of shape, style and material. Further, the end covers are not essential to the structural integrity of the toaster which also gives greater freedom in their design and the ease with which they can be removed and changed.

Although described in connection with one end wall of the cooking section and one end cover, it will be appreciated that corresponding end walls and end covers will be provided at each end of the cooking section.

Although described with reference to a two-slot toaster, it will be appreciated that the construction of the appliance of the present invention could be adapted to any number of slots and could also be adapted to form a combi toaster, sandwich toaster or bun toaster and could also be adapted for use in grills and combi grills.

In alternative forms of the invention it is envisaged that the end covers may be formed of a plastics material which could be mounted on the end wall by means of a snap connector or similar releasable fastening. In this way, it would be possible for the purchaser to remove and replace the end covers with those of a different colour if, for example, changing a colour scheme of a kitchen or restaurant.

Claims

cr 1. A cooking appliance including a centrally disposed cooking section having a frame supporting one or more heating elements, and a cover to enclose said heating elements, the cover having access means to enable items to be cooked to be placed in the heating section, at least one end cover at one end of the cooking section, and means to reduce the amount of heat from the heating element or elements which is transmitted to the end cover, characterised in that said one end of the cooking section is closed by an end wall, the end wall being enclosed by said end cover, said end wall forming a heat shield to reduce the amount of heat reaching the end cover.
2. A cooking appliance according to claim 1, wherein a said end wall is located at each end of the cooking section and each end wall being of sufficient mass to form a heat sink.
3. A cooking appliance according to claim 1 or 2, wherein the or each end wall is formed of a light metal diecasting.
4. A cooking appliance according to any one of claims 1 to 3, wherein, an inner peripheral face of the or each end cover overlies a peripheral flange on the associated end wall, said end wall having a further peripheral face against which said cooking section cover abuts to form, on the outer surface, a smooth transition between the cooking section cover and the end cover.
5. A cooking appliance according to claim 4 wherein the peripheral flange has a plurality of protuberances spaced about the periphery against which the inner peripheral face on the end cover abuts.
6. A cooking appliance according to any one of the preceding claims wherein the end cover or covers is/are formed of a light metal diecasting.
7. A cooking appliance according to any one of the preceding claims wherein the end cover or covers is/are formed of a plastics material.
8. A cooking appliance according to claim 7 wherein the or each end cover is adapted to have a snap engagement with the end wall of the cooking section.
9. A method of manufacturing an end cover for an appliance according to any one of claims 1 to 6 wherein the or each end cover is formed by diecasting in a two part mould, the end cover (s) having a planar end face adapted to abut another face or edge of the appliance, the parting line between the two parts of the mould being adjacent said planar end face.
10. A cooking appliance substantially as described herein with reference to and as illustrated in the accompanying drawings.