Patent GB-1391817-A (GB)
Title: Cooking-time clock for immediate or delayed operation of  switch contacts
IPC: G04C23/16
Filed: 1972-12-08
Abstract: 1391817 Time switches DIEHL 8 Dec 1972 [24 Jan 1972] 56867/72 Heading H1N A cooking-time clock providing immediate or delayed operation of switch contacts 51, 52 has a cooking-duration indicator 7 which is visible in a window 6 of a dial 1 and which can be preset by a first adjustment knob 5 and is coupled to means 43 for opening said contacts, and has cooking-commencement indicator hand 11 which is concentric with the hour hand 2 and which can be covered by the latter and can be preset by a second knob 4, said hand 11 being coupled via a friction coupling 34, 35, to means 43 for closing said switch contacts, and when in a position covered by the hour hand 2 is automatically coupled by an axially displaceable rotary coupling part 25, 26, to rotate synchronously with the hour hand 2, the friction coupling 34, 35, being such that rotation of the knob 5 to set the cooking duration does not alter the setting of the hand 11, and there being associated with said rotary coupling part 25, 26, a blocking lever 55 which prevents the operation of switch contacts 51, 52 unless the indicator hand 11 is covered by the hour hand 2. The moving contacts 51, 52 co-operate with fixed contacts, not shown, in the circuit of an electric cooker, As shown, a motor 12 drives a minute hand 3 by spindle 14 and hour hand 2 by hollow shaft 19 connected to hour wheel 20. Indicator hand 11 is carried on hollow shaft 26 connected to gear wheel 25 having two pins 23, 24, thereon which can enter holes 21, 22 in hour wheel 20 (as shown) and in this condition hour hand 2 is aligned with, and thus hides, the hand 11. When knob 4 is pulled outwardly lever 55 moves shaft 26 axially and gear 25 is uncoupled from hour wheel 20. A pinion 34 secured on shaft 32 is always in mesh with gear 25, and a pinion 35, loose on shaft 32, is frictionally clutched to pinion 34 by the action of a spring 36. Rotation of knob 5 sets disc 7 to indicate a cooking duration in the window 6 and rotates cam 43 to pivot lever 47 and close contacts 51, 52. This rotation of cam 43 brings a toothed part of its periphery 42 into engagement with pinion 35, and, if knob 4 has not been pulled outwardly, the drive from hour wheel 20 to gear 25 immediately starts resetting cam 43, via pinions 34, 35, back to its "OFF" position where the reaction of nose 46 on recess 44 snaps the cam 43 out of mesh with pinion 35 and opens the contacts. If, however, knob 4 is pulled and rotated to set indicator 11 to a commencement time the shaft 26 is uncoupled from hour wheel 20 and there is no clock drive to cam 43. Shaft 26 maintains shaft 32 axially displaced by means of lever 55, and the other end 56 of lever 55 prevents lever 47 from closing contacts 51, 52, the nose 46 being resiliently mounted on lever 47 to permit this condition (Fig. 6, not shown). When hour hand 2 coincides with indicator 11 pins 23, 24 can re-enter holes 21, 22, allowing spring 60 to restore the lever 55, which allows lever 47 to close contacts 51, 52. Cam 43 is now time-driven back for the duration set on disc 7, after which contacts 51, 52 are opened and the mechanism is once again in the condition shown in Fig. 4.