Patent GB-997472-A (GB)
Title: Ice block making apparatus
IPC: F25C1/04
Filed: 1964-01-23
Abstract: 997,472. Ice making. GENERAL MOTORS CORPORATION. Jan. 23, 1964 [May 27, 1963], No. 2938/64. Heading F4H. In ice block making apparatus, a resilient polyethylene or metal ice tray 25 is mounted on a shaft 44 and a pin 39 which have non-colinear axes, the shaft 44 being rotatable by a unidirectional motor to twist and distort the ice tray to loosen ice blocks. The ice making apparatus is contained in the freezing compartment 13 of a refrigerator cooled by circulation of air over an evaporator 16 and provided with a water supply pipe 113 for filling the ice tray. The motor M, having a stator 52, drives, through gearing, a toothed disc 67 having a cam track 74 engaged by a follower 83 on a freely pivoted toothed segment 76 which drives a gear 81 fixed to the shaft 44. A printed circuit board 95 is attached to the disc 67 and carries a commutator 105 engaged by spring fingers 101-104 of a fixed printed circuit board 85 which carries the components contained within dotdashed lines on Fig. 10. In the positions shown in Fig. 10 the tray and motor are stationary during freezing. A negative temperature coefficient thermister 120 is attached to the outside of the tray 25 and when freezing is complete the resistance of the thermistor has increased to a value at which the current from a power line L1 through the coil 93 of a relay 92 is sufficient to close a switch 94 to energize the motor M. As the disc 67 and commutator 105 rotate, finger 103 leaves a gap 106 in the commutator and a circuit is completed through fingers 102, 103 and the commutator to maintain the switch 94 closed. A full rotation of the disc 67 causes the shaft 44 to rotate so that the tray is twisted and distorted (Fig. 14) to loosen the ice blocks, the end of the tray remote from the shaft 44 being held by a stop 46, then tipped in the opposite direction until the remote end of the tray engages a stop 47 after which further turning against the stop 47 removes any distortion in the tray. Finally the tray is righted. During the latter part of the rotation of the disc 67 a board 95 (clockwise as seen in Fig. 10) the finger 101 contacts a part 107 of the commutator 105 and energizes the coil of a solenoid valve 116 in the water supply pipe to allow a predetermined amount of water to run into the ice tray. At the completion of a revolution, the gap 106 registers with the finger 103 to stop the motor and finger 104 contacts a part 108 of the commutator to pass current through the thermistor and relay to reset the apparatus. Ice blocks tipped from the tray 5 fall into an ice block receptacle 130 slidably supported on ledges 132 of a bracket 26 supporting the ice making apparatus. The front of the receptacle has a handle 133 which normally engages a spring 141 to maintain a slide 149 (Fig. 10) in a position completing the circuit of the relay coil 93. If the spring 141 falls due to removal of the receptacle or to its depression against supporting ledge springs 138 due to weight of ice, the slide moves to break the relay circuit. In a modification, Fig. 11 (not shown), the electric control circuit is adapted to accommodate a thermistor of positive temperature coefficient.