Patent GB-881421-A (GB)
Title: Automatic temperature responsive time-control system
Inventor: GILSON ROBERT JOHN
IPC: D06F34/08
Filed: 1957-01-23
Abstract: 881,421. Washing-machines. COLSTON Ltd., CHARLES. Jan. 17, 1958 [Jan. 23, 1957], No. 2496/57. Class 138 (2). [Also in Group XXIII and XXIV] A controller for a dish-washing machine in which at least one of the operations in a cycle of the process is dependent on temperature conditions, comprises cams driven to control the cycle of operations, a constant speed drive unit, a two-speed gear between the drive and the cams, the gear-box being actuated to change speed at the beginning of an operation by one of the cams, and a latch retaining the gear in the changed position until the desired temperature is reached by the water in the machine, a trip device then releasing the latch and restoring the gear to its original position. As shown (Fig. 1) motor M drives two-speed gear-box G and cams 6-10 by way of reduction gear H. Control lever 11 is biased towards the highspeed position in which it is shown. When the chamber C is filled with water below the desired temperature at the start of one operation in a washing cycle, a cam 33 engages one end of rod 30 and pushes it to the left against extension 13 of lever 11, putting gear-box G into low-speed drive. This movement of extension 13 allows detent 15 to move into its latched position behind the shoulder 16 of lever 17 which is prevented from upward movement by the solid fusible alloy in chamber 21, plunger element 20 being connected to chamber 21 which is connected to larger chamber 22 by a flexible bellows. When the alloy fuses upon the circulating water reaching the desired temperature, chamber 21 retracts in direction x and the latch device 15, 16 is released allowing lever 11 to re-engage high-speed drive to the cams 6-10. In a modification (Figs. 3 and 4), a two-arm trip lever 49, 50 is pivoted at 48 and maintained in the anticlockwise position by the tension of a spring 52 attached at 53 to bracket 42 on housing 43. The lower limb 49 is immersed in a fusible alloy held within chamber 41 integral with elbow 38 through which liquid from the machine is caused to flow. A driven cam 10 (Fig. 1) is followed by face 60 of slider 55 and kept in engagement with the cam by the tension of spring 72. The arm 56 of slider 55 is slidably carried in a groove 57 in gear housing 43 while its other arm 59 carries a bolt 70 on which pivots the three-armed latch lever 71, 74, 76. Cam lobes on cam 10 push face 60 to position BB when it is desired to engage low speed drive for a period controlled by the size of the cam lobe, and to position CC when the time spent at low speed is to be governed by the time taken for the water to reach the desired temperature. When one of the higher lobes engages face 60, slider 55 is moved to the left and latch lever arm 71 engages beak 78 on lever 50 in its notch 77. The latch lever will now retain slider 55 in this left position until the fusion of the alloy in chamber 41 allows lever 49 to move and latch 71 is released. Meanwhile the movement of slider 55 to the left causes head 66 of plunger 67 to engage face 65 of yoke 61 and rotate it about its pivot 62 on bracket 63, causing the engagement of low-speed drive to cam 10. The reduction of the speed of the cam is of the order of 20 to 1, high-speed drive being restored when the alloy in chamber 41 melts. When the period of drive at low speed is governed by the length of the cam lobes, face 60 is only moved to position BB and latch lever 71 does not engage lever 50, the actuation of yoke 61 being ensured for latched or unlatched positions of slider 55 by the lost motion between slider 55 and plunger 67 urged by spring 69. Arm 76 is provided as a hand release for the slider and arm 74 engages stop 75 when the latch lever 71 is unlatched. In an alternative embodiment (Figs. 5 and 6), trip lever 50<SP>1</SP> is mounted on a rotatable stud or pin 80, attached to which is serrated wheel 81 which is immersed in fusible alloy in housing 82 attached to a section of pipe 84 in the liquid circulating system. Specification 832,756 is referred to.