GB2169493A

GB2169493A - Bimetallic timing mechanism

Info

Publication number: GB2169493A
Application number: GB08530395A
Authority: GB
Inventors: Karlheinz Frank
Original assignee: Rowenta Werke GmbH
Current assignee: Rowenta Werke GmbH
Priority date: 1984-12-12
Filing date: 1985-12-10
Publication date: 1986-07-16
Also published as: IT8522948A0; HK10889A; ES296436U; FR2574611A1; GB8530395D0; NL8502786A; IT1185736B; KR910005036B1; DE3445224C1; KR860005551A; GB2169493B; ES296436Y; FR2574611B1

Abstract

A bimetallic timing mechanism is provided for an electrically heated toaster in which a latchable bread carriage acts to switch the toaster on and off. The mechanism comprises a bimetallic component 4, a switching lever 5 adapted to unlatch an engaging lever of the bread carriage in response to deflection of the bimetallic component, a pivot pin 2 fixed to a frame 1 of the timing mechanism and having said bimetallic component and said switching lever mounted in freely movable manner thereon, a knob 6 mounted to the frame for regulating the toasting time, and a compression spring 7 arranged to hold the bimetallic component 4 and the switching lever 5 on the pin. During toasting the bimetallic component 4 attains a predetermined deflection whereupon the component cools and returns to its original position, the switching lever 5 being arranged to unlatch the bread carriage when the bimetallic component returns to its original position. <IMAGE>

Description

SPECIFICATION Bimetallic timing mechanism The invention relates to a bimetallic timing mechanism for electrically heated toasters in which a latchable bread carriage acts to switch the toaster on and off.

A bimetallic timing mechanism is known from German Patent No. 21 31 977 which comprises an electrically heated bimetallic component which switches off its own heating element via a switching lever on attaining a predetermined deflection and, after bending back into its initial position, releases the locking of the bread carriage, thereby ending the toasting operation, and a regulator knob for adjusting the toasting time. In this timing mechanism the switching lever is latched behind a control slide and the bimetallic component is pressed against the slide by spring force. In the first position of engagement the bimetallic component is heated by its heating element which is connected thereto. After a predetermined deflection, the bimetallic component latches into a recess provided on the slide and the heating of the bimetallic component itself is switched off.In the course of cooling, the bimetallic component swings back into its original position and thereby moves the control slide, as a result of which the slide releases the switching lever and releases the bread carriage. The manufacturing costs ofthis known bimetallictimer are very high since it consists of a large number of individual parts and, during automatic assembly, accurate alignment of the individual parts is required at several points in orderto match the manufacturing and assembly tolerances of the numerous compo nents ofthetiming mechanism. Moreover, the calibra- tion of the timer, i.e. its pre-setting after assembly, presents considerable difficulties.

Viewed from one aspect the invention provides a bimetallictiming mechanism for an electrically heated toaster in which a latchable bread carriage acts to switch the toaster on and off, comprising a frame, a bimetallic component, a switching lever adapted to unlatch the bread carriage in response to deflection of the bimetallic component, mounting means on said frame of the timing mechanism, said bimetallic component and said switching lever being mounted in freely movable manner on said mounting means, regulating means mounted to the frame for regulating thetoastingtime,and a compression spring arranged to hold the bimetalliccomponentandthe switching lever on the mounting means.

A bimetallic timer according to the invention may consist of few individual parts, be easy to assemble and able to be calibrated after assembly without any difficulty. In particularthe compression spring enablesthe bimetallic component and the switching leverto be mounted in freely movable manner on the mounting means e.g. a pivot pin without any additionalfixing means. Atthe sametime,the compression spring can press onto the bimetallic component and the switching lever with a predetermined force and thereby can impartthe necessary biasing to the bimetallic component and give the switching lever the correct switching position.

The regulating meansmayforexamplecomprisea regulatorknobinwhich case the compression spring might be arranged to urge the regulator knob towards the frame ofthetiming mechanism with a constant pressure and thereby hold it in position. Preferably the compression spring is arranged at least partly inside the regulator knob and substantially concentrically therewith.

The regulating means preferably includes means for adjusting the relative positions of the switching lever and the bimetallic component.

Preferably an adjusting arm is arranged on the switching lever and is operatively connected to the regulating means, there being a calibration screw for pre-setting the adjusting arm. With such an arrange mentthe travel of the switching lever and hence the desired toasting time can be preselected. A blocking lug may be provided on the switching leverto limit the adjustment of the lever relative to the frame so that it would not be possible to make an adjustment which would prevent the toaster from being switched off.

A heating elementforthe bimetallic component may be slidably mounted on both sides ofthe bimetallic component and be pressed against the bimetallic component by a spring clip for better heat transfer, so that the bimetallic component is able to deflectfreely at anytime. All the components ofthe bimetallictimer are preferably connected to the housing of the timing mechanism without any additional securing elements such as screws, rivets, etc., thus simplifying the assemblyofthetiming mechanism substantially so that it can be automated.

Viewedfromanotheraspecttheinvention provides a bimetallic timing mechanism for an electrically heated toaster in which a latchable bread carriage acts to switch the toaster on and off, comprising a frame, a bimetallic component, electrical heating means for said component, means for switching off said heating means when said bimetallic component attains a predetermined deflection whereupon the component cools and returns to its original position, a switching lever adapted to unlatch the bread carriage when said bimetallic component returns to its original position so asto switch the toaster off, a pin fixed to said frame ofthetiming mechanism, said bimetallic component and switching lever being mounted in freely movable manner on said pin, a regulator knob mounted to the frame for regulating the toasting time, and a compression spring arranged at least partly inside said regulator knob and substantially concentrically there- with, said spring acting to hold the bimetallic compo nent and the switching lever on the pin. Preferably the means for switching off the heating means for the bimetallic component includes said switching lever.

An embodiment ofthe invention will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 shows diagrammatically the bimetallic timing mechanism according to the invention in front elevation; Figure 2 shows the bimetallic timing mechanism in plan view; Figures 3a to 3c show various switching positions of the timing mechanism in diagrammaticview.

The bimetallic timing mechanism shown consists of aframe 1 on which are mounted a pin 2 and a stop3.A bimetallic component4and a switching lever 5 are mounted in freely movable manner on the pin 2. Both parts are secured on the pin 2 by a regulator knob 6 with a compressionsspring 7 arranged therein. The regulator knob 6 is releasably mounted on the frame 1 by a snap-fitconnection and the compression spring 7 is centred by the pin 2. A bimetallic heating element8 has oblong holes 9 and is loosely riveted to the bimetallic component4. A spring clip 10 presses the heating element8againstthe bimetalliccomponent4 and thus ensures a good heattransfer.On the switching lever5 is provided a lug 11 which comes into force in the eventofawrong adjustment of an adjusting arm 12 and blocksthe switching lever 5 againsttheframe 1.

With the aid of the timing mechanism the toasting time of a toaster is controlled. The operation ofthe timing mechanism is controlled. The operation of the timing mechanism is as follows.

The regulator knob 6 is mounted within the frame 1 of the timing mechanism, and is used together with cam 13 to reduce or increase the switching distance of the switching lever 5 and hence the deflection of the bimetallic component4. Movement ofthe cam 13 is transmitted to the switching lever 5 via the adjusting screw 14 on the adjusting arm 12 and in this way the desired toasting time forthe bread is preselected. The bread carriage (notshown) with an engaging lever 15 mounted thereon is moved downwards into the toasting position by means of an actuating knob (not shown). The engaging lever 15 is now latched down by the switching lever 5 and thefree end of the switching lever 5 is restrained by the bimetallic component 4 as seen in Fig. 3a.The free end ofthe bimetallic component4 abuts on the frame 1, whilst in the region ofthe pin 2the bimetalliccomponent4 abuts on the frame 1 only at its turning point 16 (Figs.

1,2 and 3a). The circuitsforthe bimetallic heating element8 andforthe heating elementforthetoasting chamber (notshown) are closed. The cold bimetallic component 4 and the toasting chamber are heated.

The bimetallic component4 deflects in the direction of the arrowshown in Figure 2 abouttheturning point 16. As a result of the deflection, the bimetallic component4firstengagestheframe 1 in the region of the pin 2. As a result of this period of advance ofthe bimetallic component4, i.e. the distance from the resting position until itcomestoabutontheframe 1, the temperature differences within the toasting chamber in a cold or preheated toaster are equalised. The bimetalliccomponent4then deflectsfurther in the direction ofthe horizontal arrow of Fig. 3a and releases its connection with the switching lever 5 (Fig.

3b). The switching lever 5, no longer restrained bythe bimetalliccomp6nent4, is caused to pivotaboutthe pin 2 by a spring (notshown) acting on the engaging lever 15 until it is arrested by the stop 3. The bimetallic heating element8 is atthistime switched offwhilstthe toasting chamber is heated still further.

The bimetalliccomponent4coolsoffand pivots back into its initial position, and in doing so it engages and displaces the switching lever so that it is released from its arrested position in engagement with the stop 3 (Fig. 3c). The switching lever 5 then rotates further aboutthe pin2and unlatchesthe engaging lever15 of the bread carriage. The heating forthetoasting chamber is then switched off and the bread carriage moves back upwards into its initial position in which thetoastedslicesofbreadcan be removed from the toasting chamber.

Modification to the specific embodiment and to any broad aspects thereof referred to or suggested herein may be apparentto those skilled in the art and the disclosure hereof is intended to encompass any such modifications.

Claims

1. A bimetallic timing mechanism foran electrically heated toaster in which a latchable bread carriage actstoswitchthetoasteron and off, comprising a frame, a bimetallic component, a switching lever adapted to unlatch the bread carriage in response to deflection ofthe bimetallic component, mounting means on said frame ofthetiming mechanism, said bimetallic component and said switching lever being mounted in freely movable manner on said mounting means, regulating means mounted to theframefor regulating the toasting time, and a compression spring arranged to hold the bimetallic component and the switching lever on the mounting means.

2. A mechanism as claimed in claim 1, wherein said regulating means includes means for adjusting the relative positions of said switching lever and said bimetallic component

3. A mechanism as claimed in claim 1 or2, wherein said regulating means comprises a regulator knob.

4. A mechanism as claimed in claim 1,2 or, wherein the mounting means comprises a pivot pin.

5. A mechanism as claimed in any preceding claim, wherein an adjusting arm is arranged on the switching lever and is operatively connected to the regulating means, there being a calibration screwfor presetting the adjusting arm.

6. A mechanism as claimed in any preceding claim, where a heating elementforthe bimetallic component is mounted in freely movable manner thereon and is pressed thereagainst by a spring clip.

7. A bimetallictiming mechanismforan electrically heated toaster in which a latchable bread carriage acts to switch the toaster on and off, com prising a frame, a bimetallic component, electrical heating meansforsaid component, meansforswitching off said heating means when said bimetallic component attains a predetermined deflection whereupon the componentcoolsand returnstoitsoriginalposition,a switching lever adapted to unlatch the bread carriage when said bimetallic component returns to its original position so as to switch the toaster off, a pin fixed to said frame ofthe timing mechanism, said bimetallic componentandswitching lever being mounted in freely movable manner on said pin, a regulator knob mounted to the frame for regulating the toasting time, and a compression spring arranged at least partly inside said regulator knob and substantially concentricallytherewith, said spring acting to hold the bimetal lic component and the switching lever on the pin.

8. A bimetallic timing mechanism for an electrically heated toastersubstantially as hereinbefore de scribed with reference to the accompanying drawings.