GB1573011A - Electric toasters - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO ELECTRIC TOASTERS (71) We, HOIPOINT LIMITED, of Peterborough, England, a British Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to electric toasters of a kind in which movement of a slice of bread to a toasting position is effected manually by depressing a bread support and return movement is effected automatically on completion of the toasting operation.

According to the present invention an electric toaster of the kind referred to comprises supporting means for supporting a slice of bread for movement from an original elevated position to a lower toasting position adjacent electric heating means, a return spring means arranged to urge the supporting means towards the original position, a latch for holding the supporting means in a toasting position against the action of the return spring means, and thermally responsive means arranged to release the latch automaticaly and thereby permit the supporting means to return to the elevated position when the bread has been toasted to a predetermined degree, the latch comprising first and second latching members having co-operating latching surfaces movable into engagement with each other to prevent movement of the supporting means from the toasting position to the elevated position, and the thermally responsive means being arranged to cause movement of the first latching member so as to disengage its latching surface from that of the second latching member and thereby effect the automatic release of the supporting means, and the toaster incorporating also manually operable means arranged to cause movement of the second latching member so as to disengage its latching surface from that of the first latching member to effect the manual release of the supporting means independently of the thermally responsive means.

Conveniently, the first and second latching members comprise pivotally mounted levers which are rotatable to disengage the co-operating latching surfaces in response to the operation of the thermally responsive means and the manually operated means respectively.

Preferably the first latching member is biased towards a non-operative position in which its latching surface will not engage the co-operating latching surface of the second latching member, and the toaster includes means for rotating the first latching member against the bias into an operative position in which its latching surface engages the co-operating latching surface of the second latching member when the supporting means is moved to the toasting position, and locking means capable of engaging the first latching member and holding it in the operative position, the lockiitg means being automatically releasable from the first latching member under the action of the thermally responsive means.

Movement of the supporting means from the toasting position of the elevated position on disengagement of the latching surface of the second latching member from that of the first latching member by the manually operated means in such an arrangement preferably causes the first latching member to be returned to its nonoperative position.

Preferably a part of the locking means is arranged to be contacted by a co-operating part of the supporting means on movement of the latter from the toasting position to the elevated position following the manual release of the co-operating surfaces of the latching members, which contact causes the locking means to release the first latching member and allow it to return to its non-operative position.

The thermally responsive means may be constituted by a thermostat device of the kind described in our copending patent application No. 52573/75 (Serial No.

1 566 102).

Thus the thermally responsive means conveniently comprises a support, a substantially rigid arm pivotally carried by the support, spring biasing means tending to rotate the arm about its pivot relative to the support, and an element of wire or ribbon-like form held in a tensioned condition between regions of the arm and support which are spaced from the pivot and restraining the arm against rotation, the element being formed of a material having a coefficient of thermal expansion greater than that of the material of the arm such that, when the assembly is heated, the resultant differential expansion of the element and arm permits the arm to rotate under the action of the biasing means, and the arm being arranged to act on the locking means, so as to cause it to release the first latching member, when rotated by a predetermined amount.

Preferably the toaster includes a switch operative to energise the electric heating means automatically when the supporting means is moved into the toasting position, and arranged to be released so as to de-energise the heating means on movement of the supporting means from the toasting position under the action of either the thermally responsive means or the manually operated means.

The toaster may include a spring arranged to transmit the motion of the supporting means to the switch when the supporting means is moved into the toasting position, so as to permit the supporting means to be moved past the toasting position after closure of the switch contacts, for facilitating the engagement of the cooperating surfaces of the latching members on subsequent return of the supporting means to the toasting position, and which spring serves to maintain a closing pressure on the switch contacts whilst the supporting means is retained in the toasting position by the latching members.

The supporting means of a toaster in accordance with the invention conveniently carries a projecting arm by which it can be lowered into the toasting position, the arm being pivotally carried by the supporting means, such that upward pressure on the projecting end of the arm produces a pivoting movement of the arm which actuates the second latching member and disengages its latching surface from that of the first latching member.

The invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a sectional side elevation of an electric toaster in accordance with the invention; Figure 2 is an end elevation of the toaster shown in Figure 1 with an outer casing removed; Figure 3 is a fragmentary perspective of a bread support latching and release mechanism shown in elevation in Figure 2, but with the bread support in a toasting position; Figure 4 is a fragmentary perspective view similar to Figure 3, but showing the bread support in the process of being released automatically by a thermostat; Figure 5 is another fragmentary perspective view similar to Figure 3, but showing the bread support in the process of being released by manual operation; and Figure 6 is a fragmentary perspective view of parts of a release mechanism shown in Figure 3, but drawn from a different angle and to a larger scale than that Figure.

Referring to the drawings, the electric toaster comprises an inner casing 1 having two elongate openings 2 at the top through which slices of bread (not shown) can pass edgewise into a toasting chamber 3 bounded at opposite ends by end plates 4 and 5 forming part of the inner casing 1.

Within the toasting chamber 3 is accommodated a bread support 6 having at each end two lugs 7 which project out of the toasting chamber 3 through respective guide slots 8 in end plates 4 and 5. The guide slots 8 extend vertically to allow the bread support 6 to be moved between an upper, released, position shown in Figure 1 in which slices of bread carried by the support project through the slots 2, to toasting position, shown in Figure 3, in which slices of bread carried by the bread support 6 are in close proximity with the heating element (not shown). The inner casing 1 is provided with an outer cover 9 shown only in Figure 1.

The lugs 7 which project through the guide slots 8 in the end plate 4 at one end of the toaster are secured to a generally L-shaped mounting plate 10 carrying parts of the toaster operating mechanism as will subsequently be described, the plate being arranged to slide up and down a cylindrical rod 11 extending vertically between a horizontally extending flange 12 at the lower end of the plate 4 and a horizontally extending flange 13 at the upper end of the plate 4. Flanges 14 at the extremities of the vertically extending limb 15 of the mounting plate 10 are provided with swaged holes 16 which encircle the rod 11 to permit the sliding movement, while the lugs 7 are secured to the rear face of the horizontally extending limb 17 to support the mounting plate 10.A helical spring 18 extending between the flange 13 and the flange 14 at the lower end of the limb 15 is arranged to urge the mounting plate 10 and the bread support 6 to the upper position shown in Figures 1 and 2 in which the lugs 7 are near the upper ends of the guide slots 8.

An L-shaped member 19 integral with the vertically extending limb 15 of the mounting plate 10 has an arm 20 which extends normally to the end plate 4 and on which is pivotally mounted a lever 21. The end of the lever 21 away from the end plate 4 cxtends through a slot 22 in the outer casing 9 and has secured to its extremity an operating knob 23.

The end of the lever 21 extending towards the end plate 4 is provided with a projection 24 which extends through a rectangular aperture 25 formed in the arm 20, so that the upper and lower edges of the aperture 25 limit the pivotal movement of the lever 21. A second projection 26, also provided on the end of the lever 21 and which extends parallel to end plate 4 (see Figure 6), is arranged to co-operate with a projection 27 provided on an Lshaped latching member 28 pivotally mounted on the limb 15 of the mounting plate 10. The vertically extending limb 29 of the member 28 has two projections 30 and 31 at its upper end which extend towards the end plate 4 with their planes normal to each other.The horizontally extending limb 32 of the latching member 28 acts as a counterweight which tends to maintain the member 28 in the position shown in Figure 3 in which the projection 31 engages the vertically extending edge 33 of the mounting plate 10.

Pivotally mounted on the end plate 4 is another L-shaped latching member 34 which is biased in a clockwise direction by a spring 35 and has a projection 36 at the end of one arm 37 and a further projection 38 at the end of the other arm 39.

A locking member 40 is also pivotally mounted on the end plate 4 so that the tip 41 of one arm 42 can engage the projection 38 on the lever 34, and the tip 43 of its other arm 44 can be engaged by the end of a rod 45 forming part of a thermostat 46 accommodated in the toasting chamber 3. The thermostat 46 may be of the kind described in our co-pending -patent application No. 52573/75 (Serial No. 1 566 102).

The toaster so far described operates in the following manner. With the bread support 6 in the upper position shown in Figure 1 so that other parts of the latching and release mechanism are in the positions shown in Figure 2, slices of bread are inserted edgewise through the openings 2 so that they rest on the bread support 6. The operating knob is then depressed so that the arm 21 is moved towards the bottom of the slot 22 causing the bread support 6 to travel downwards towards the toasting position shown in Figure 3, carrying with it the mounting plate 10 which slides down the rod 11.

Downward movement of the mounting plate 10 from its upper position causes the projection 31 on the latching member 28 to move downwards until its underside moves past the projection 36 on the latching member which at this point will be in a non-latching position. Further downward movement of the mounting plate 10 causes the projection 30 of the latching member 28 to engage the horizontally extending arm 39 of the latching member 34 thus producing an anti-clockwise rotation of the member 34 which causes the projection 36 to move into a position in which it engages the upper surface of the projection 31 and prevents upward movement of the bread support as shown in Figure 3. The anticlockwise rotation of the latching member 34 brings the projection 38 at the end of the horizontally extending arm 39 of the latching member 34 beneath the lower end of the pivotally mounted locking member 40.This allows the locking member to rotate on a clockwise direction under gravity so that the tip 41 of the downwardly projecting arm 42 engages the upper surface of the projection 38 on the latching member 34 and thereby holds the latter in its latching position against the bias of the spring 35. The bread support 6 is therefore securely latched in the toasting position.

As toasting proceeds the temperature in the toasting chamber 3 rises, heating the thermostat 46 and causing the rod 45 to move upwardly and engage the tip 43 of the arm 44 of the locking member 40. The rod 45 continues to move upwardly urging the arm 42 in an anti-clockwise direction.

When the bread has been toasted to a predetermined degree the rod 45 has moved sufficiently to cause the tip 41 of the arm 42 to disengage the projection 38 on the latching member 34 as shown in Figure 4, allowing the member 34 to pivot in a clockwise direction urged by the spring 35.

This clockwise movement of the lever 34 moves the projection 36 clear of the projection 31 on the second latching member 28 thus allowing the mounting plate 10 and with it the complete bread support 6 to return to the upper position urged by the spring 18.

Alternatively, - if it is desired to return the bread support 6 to the upper position prior to automatic operation by the ther mostat 46, upward pressure is applied to the operating knob 23 thus raising the end of the lever 21 which is away from the end plate 4 and depressing the end of the lever 21 which is towards the end plate 4. Consequently the projection 26 on the lever 21 bears down on the projection 27 on the latching member 28, causing the latter to pivot in an anti-clockwise direction until the projection 31 moves clear of the projection 36 on the latching member 34 as shown in Figure 5 the latching member 34 remaining in the latching position. The mounting plate 10 and with it the bread support 6 then return to the upper position urged by the spring 18.

An edge 48 of the downwardly extending arm 42 of the locking member 40 is of cam shape and the mounting plate 10 is provided with an inwardly projecting lug 49 on edge 50 of which, when the bread sup port is raised, manually engages the camshaped edge 48 of the locking member 40 and rotates the latter slightly in the anticlockwise direction causing the tip 41 of the downwardly projecting arm 42 of the locking member to release the latching member 34 which returns to its non-latching position by virtue of the spring 35, and is thus appropriately positioned for the lowering of the bread support at the commencement of a subsequent toasting operation.

In order to avoid placing undue strain on the thermostat, which might adversely affect its calibration, it will be seen that release of the latching mechanism is achieved independently of automatic release by the thermosta;.

In some cases the cam surface 48 of the locking member 40 may be omitted so that the latching member 34 is retained in the latching position when the bread support is raised manually. In such a case the cooperating projections 31 and 36 on the latching members 28 ad 34 can be so shaped and arranged that as the bread support is subsequently lowered the projection 31 is urged sideways by a wiping movement as it contacts the upper surface of the projection 36, this producing a pivoting movement of the latching member 28 in the anti-clockwise direction and allowing the projection 31 to pass the projection 36. The latching member 28 then returns to its original position so that the projection 31 then lies beneath the projection 36 so that when the knob 23 of the bread support is released the support is again retained in the toasting position.

Energisation of the heating elements is effected by means of a switch (not shown) whi is arranged to be closed auto matically on downward movement of the bread support into the toasting position; the switch is conveniently a double pole switch fixed to the base of the toaster and carrying a pair of fixed contacts and above them a pair of movable contacts carried by leaf springs which are substantially horizontal in the non-operated or open position. Each of the leaf springs has attached to its upper surface a further leaf spring of V-shape with one arm of the V secured to the respective contact spring and the other inclined at an angle in the upward direction.

An insulated actuating member fixed to the lower end of the mounting plate is arranged to engage the V-springs when the bread support is lowered towards the toasting posirion. Further movement compresses the V-springs and finally causes the closure of the switch contacts. The deformation of the V-springs ensures that the contacts are held in the closed position when the bread support is latched into the toasting position but are opened on release of the support. Such an arrangement is described in more detail in co-opending patent application No. 1894/77 (Serial No.

1 573 012).

The bread support 6 conveniently consists of a pair of metal strips each bent into a multiwave shape by transverse corrugations and supported with an edge uppermost beneath a respective one of the slots 2, the toaster incorporating, within the lower part of the inner casing, two bread arresters (not shown) comprising a number of transverse rods positioned so that they register vertically with the loops of the corrugations of the respective one of the bread support strips, so that as the latter are lowered the rods act as arresting members which engage the lower edges of the slices of bread and bring them to rest opposite the heating elements, whilst permitting the bread support, together with the mounting plate, to be lowered still further, to actuate the heating element switch, the bread support being latched in this lower position by the latching members 28, 34, as already described. Then when the bread support 6 is released, either by the thermostat 46 at the end of a toasting operation, or manually by the knob 23, the switch contacts are opened, and the heating elements de-energised, before the bread support strips engage the slices of bread to raise them to the elevated position in which they project from the toaster. This has the advantage that if a slice of bread becomes curled or twisted during a toasting operation so that it becomes jammed within the toaster and prevents further upward movement of the bread supports the risk of the toast burning or bursting into flames is avoided since the heating elements are already de-energised.

Claims (10)

WHAT-WE CLAIM IS:

1. An electric toaster of the kind referred to comprising supporting means for supporting a slice of bread for movement from an original elevated position to a lower toasting position adjacent electric heating means, a return spring arranged to urge the supporting means towards the original position, a latch for holding the supporting means in the toasting position against the action of the return spring, and thermally responsive means arranged to release the latch automatically and thereby permit the supporting means to return to the elevated position when the bread has been toasted to a predetermined degree, the latch comprising first and second latching members having co-operating latching surfaces movable into engagement with each other to prevent movement of the supporting means from the toasting position to the elevated position, and thermally responsive means being arranged to cause movement of the first latching member so as to disengage its latching surface from that of the second latching member and thereby effect the automatic release of the supporting means, and the toaster incorporating also manually operable means arranged to cause movement of the second latching members so as to disengage its latching surface from that of the first latching member to effect the manual release of the supporting means independently of the thermally responsive means.

2. An electric toaster according to Claim 1 wherein the first and second latching members comprise pivotally mounted levers which are rotatable to disengage the co-operating latching surfaces in response to the operation of the thermally responsive means and the manually operated means respectively.

3. An electric toaster according to Claim 2 wherein the first latching member is biased towards a non-operative position in which its latching surface will not engage the co-operating latching surface of the second latching member, and the toaster includes means for rotating the first latching member against the bias into an operative position in which its latching surface engages the co-operating latching surface of the second latching member when the supporting means is moved to the toasting position, and locking means capable of engaging the first latching member and holding it in the operative position, the ]ocking means being automatically releasable from the first latching member under the action of the thermally responsive means.

4. An electric toaster according to Claim 3 wherein movement of the supporting means from the toasting position to the elevated position on disengagement of the latching surface of the second latching member from that of the first latching member by the manually operated means causes the first latching member to be returned to its non-operative position.

5. An electric toaster according to Claim 4 wherein a part of the locking means is arranged to be contacted by a co-operating part of the supporting means on movement of the~latter from the toasting position to the elevated position following the manual release of the co-operating surfaces of the - latching members; which contact causes the locking means to release the first latching member and allow it to return to its non-operative position.

6. An electric toaster according to Claims 3, 4 or 5 wherein the thermally responsive means comprises a support, a substantially rigid arm pivotally carried by the support, spring biasing means tending to rotate the arm about its pivot relative to the support, and an element of wire or ribbon-like form held in a tensioned condition between regions of the arm and support which are spaced from the pivot and restraining the arm against rotation, the element being formed of a material having a coefficient of thermal expansion greater than that of the material of the arm such that, when the assembly is heated, the resultant differential expansion of the element and arm permits the arm to rotate under the action of the biasing means, and the arm being arranged to act on the locking means, so as to cause it to release the first latching member, when rotated by a predetermined amount.

7. An electric toaster according to any preceding claim including a switch operative to energise the electric heating means automatically when the supporting means is moved into the toasting position, and arranged to be released so as to de-energise the heating means on movement of the supporting means from the toasting posi tion under the action of either the thermally responsive means or the manually operated means.

8. An electric toaster according to Claim 7 incorporating a spring arranged to transmit the motion of the supporting means to the switch when the supporting means is moved into the toasting position, so as to permit the supporting means to be moved past the toasting position after closure of the switch contacts, for facilitating the engagement of the co-operating surfaces of the latching members on sub sequent return of the supporting means to the toasting position, and which spring serves to maintain a closing pressure on the switch contacts whilst the supporting means is retained in the toasting position by the latching members.

9. An electric toaster according to any preceding claim wherein the supporting means carries a projecting arm by which it can be lowered into the toasting position, the arm being pivotally carried by the supporting means, such that upward pressure on the projecting end of the arm produces a pivoting movement of the arm which actuates the second latching member and disengages its latching surface from that of the first latching member.

10. An electric toaster of the kind referred to substantially as shown in and as hereinbefore described with reference to Figures 1 to 6 of the accompanying drawings.