Patent GB-926965-A (GB)
Title: Improvements in or relating to thermally responsive actuators
IPC: F25C1/24
Filed: 1959-10-20
Abstract: 926,965. Motors operated by expansion of solids. DOLE VALVE CO. Oct. 20, 1959 [Oct. 27, 1958], No. 35539/59. Class 10. [Also in Group XIII] A thermally-responsive actuator 12, Fig. 1, for rotating, with a step-by-step motion, a tray 14 of an ice maker 11, comprises a known solidfilled type thermally responsive element 45, Fig. 2, having a slidable piston 55 connected through a motion converting means 65, 75, 105 and 39 with the tray 14; an electric resistor heater 47 surrounding the element 45, and a water-filled heat retaining well 49 surrounding the heater to control the operating time of the piston 55 and thus the ice maker 11. The tray 14 has three sets of ice moulds 16, spaced 120 degrees apart and is rotatably mounted in a frame 13 by studs 14a, 15 on end walls of the tray, the stud 15 having a driving connection with the actuator 12. When water in the uppermost ice moulds has frozen the actuator turns the tray through one step whereby an empty set of moulds is disposed uppermost to receive hot water which serves to thaw the ice pieces from the downwardly inclined moulds whereby they can be collected in a basket (not shown). The driving member 39, Fig. 2, connectible at 40 with the stud 15 has ratchet teeth 41 engageable with a spring-urged plunger 42 to index the position of the tray. The actuator 12 comprises a hollow stepped casing 33 in which is reciprocable, by the piston 55 against the urge of a spring 59, an externally threaded member 65 having longitudinal keys 69 slidably engaging key slots 67 in the casing to prevent rotation of the member 65. The latter engages the internal threads 73 of a drive member 75 rotatably supported in the casing and connecting through a known winding spring clutch 105 with the member 39. The drive member 75 has a flange 76 provided with a lateral lug (not shown) engaging in a part annular slot in a cam ring 83 surrounding the flange 76 and rotatable in the casing 33, lost motion thus being provided between the lug and the ring to allow of an amount of relative rotation between the member 75 and the ring. The movement of the member 65 to the right is limited by a stop flange 70 having a retainer on the cylinder 56 of the element 45. The element 45 is normally held in position in the casing by a clamp ring 57 between the flange 70 and a washer 58 carried in a heat insulator 50 secured in the casing 33 and slidably enclosing the heat wall 49. Should the piston 55 overtravel, the washer 58 and wall 49 can then yield against a spring 51. The cam ring 83 has an annular flat surface 85 and at one position a recessed portion (not shown), the surface 85 or the recessed portion being engageable with a follower 86 on an operator member 87 slidable within a chamber 89 in the casing 33 and having a spring-controlled plunger 31 adapted to operate through a ball 27, a push-button electric switch 30, controlling an electric circuit for the electric heater 47 and solenoids and a heater for a water metering device supplying the tray, as described with reference to Fig. 6 (not shown). The ball 27 is carried in an arm 26 on a rotatable shaft 23 provided at its other end with an arm 21 operable by ice pieces filling the basket (not shown). The arm can also be operated by camming lugs 19 on the tray end wall 17, the arrangement being such that the switch is inoperative when the ball 27 is removed by the arm and the basket for ice cubes is full. When the ports are in the position shown in Fig. 2, the element 45 is cool, the follower 86 is on the flat surface 85 of the cam ring 83 and the switch 30 is operated to energize the electric heater 47, a water metering device to supply the tray 14, and a heater for the water. Thereafter the element 45 and the well 49 are heated, frozen water in the well initially delaying the heating action. In due course the piston 55 will move to the left to rotate the drive member 75. Eventually the lug on the drive member 75, normally engaging one end wall of the port annular slot in the cam ring, will engage the other end wall to cause the follower 86 to enter the recessed portion of the ring and relieve the push button switch, whereby the heaters and water metering solenoid are de-energized. The heat stored in the well 49 causes further outward movement of the piston to cause rotation of the tray 14 through the clutch spring 105. When the element starts to cool its cooling time is delayed by the well 49 so that the return of the ports by the spring 59 is delayed. Firstly the water in the well is frozen as the water in the ice moulds is frozen and the lug on the member 75 engages the other slot end in the cam ring to cause the closing of the switch 30 in readiness for a further operating cycle.