GB986942A - Control devices for ovens or burners - Google Patents

Abstract

986,942. Timing apparatus for controlling cooking. ROBERTSHAW CONTROLS CO. March 26, 1963 [April 12, 1962], No. 11957/63. Heading A4D. [Also in Division H2] A timer for a gas or electric oven institutes the cooking period as soon as it is set and, thereafter, reduces the oven temperature to keep the cooked food warm until it is required. The oven temperature is varied by a thermostatic control operated by temperature setting knob 50 on control shaft 51. The operation of a time setting knob 52 is linked with that of the temperature setting knob 50 so that the former is inoperable when an untimed cooking operation is taking place. To set the timer, the knob 50 must first be positioned at a temperature setting below the food warming temperature and, in such a position, pawl 115 can be moved into the patch of notch 82 by rod 118 or lever 108. Subsequent movement of the time setting knob 52 pivots the lever 108 and brings both pawls 114 and 115 into operating positions. Simultaneously, the drive to continuously running timer 42 is broken by displacement of pinion 98 against the force of tension spring 105. When the knob 52 has been turned through an angle corresponding to the desired cooking period, spring 105 re-establishes the drive between timer 42 and wheel 95. The latter is subsequently driven back by timer 42 to its original position in which the mutilated portion 97 is opposite pinion 98. Knob 50 drives only one, 85, of discs 78, 85 and 86 directly. The movement of shaft 51 is transmitted to disc 86 by pin 89 engaging slot 90 and to disc 78 through tension spring 91. At the food warming temperature setting, disc 78 is brought to rest by the engagement of notch 82 with pawl 115. Subsequent movement of knob 50 to higher temperature settings, together with discs 85 and 86, winds up spring 91. On release of knob 50, pawl 114 retains disc 86 against the torsion of spring 91. However, if the temperature setting is inadvertently adjusted beyond the intended value, a pawl-unlocking mechanism can be used to enable knob 50 to be rotated back again. The unlocking is produced by using the lost-motion between discs 85 and 86 to cause pawl 114 to ride up on teeth 88 out of engagement with teeth 87. As the cooking period ends and lever 108 falls back into notch 107 under spring 134, pawl 114 is retracted by means of pin 120. Discs 85 and 86 are thus released and rotate, together with shaft 51, under the action of spring 91 until rod 89 comes into contact with roller 83a. The temperature is accordingly adjusted to the food warming setting and roller 83a is retained in notch 133 of lever 125 until the action of lever 125 is overcome by turning knob 50 to the off position. The apparatus may be modified (Figs. 23-28, not shown) to allow variation or adjustment of the food warming temperature. Specification 938,800 is referred to.