Pressure responsive electric switch, particularly an evaporator thermostat for refrigerators
First Claim
1. A pressure responsive electric switch assembly, comprising, an actuating element mounted for displacement between first and second extreme positions, switch means actuated by said actuating element having on and off states corresponding to said positions, pressure responsive motor means responsive to applied pressures biasing said actuating element in the one direction, displacement control means for controlling the displacement of said actuating element during a constantly increasing motive pressure applied to said motor means to provide a substantially null displacement for a substantial intermediate pressure range between upper and lower pressure ranges, said displacement control means including first and second series connected spring means for biasing said actuating element in the off direction and a coupling member connecting said first and second spring means, anchor means for holding one end of said first spring means in a relatively fixed position, means attaching one end of said second spring means to said actuating element, stationary first abutment means for arresting movement of said coupling member after a predetermined displacement at a position corresponding to a predetermined lower pressure applied to said motor means, second abutment means attached to and carried by said actuating element for engagement with said coupling member when said applied pressure is lower than a predetermined higher pressure applied to said motor means, said first and second abutment means being effective to prevent said first and second spring means from deforming during said intermediate pressure range.
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Abstract
The invention relates to a pressure responsive electric switch assembly of a type used as evaporator thermostats for refrigerators. In this unit an actuating element for operating a switch is held in equilibrium by two springs acting in opposition to a bellows which is connected to a temperature sensor capsule containing a liquid-vapor filling. An abutment arrangement is provided for the springs so that, despite a constantly rising pressure in the bellows, the actuating element operated by the bellows has a zero or null displacement range which corresponds to a substantial intermediate pressure range to which the bellows is subjected by the temperature sensor. As there is no movement by the actuating element in this intermediate range, there is an avoidance of wear which would otherwise be caused by this movement.
4 Citations
3 Claims
- 1. A pressure responsive electric switch assembly, comprising, an actuating element mounted for displacement between first and second extreme positions, switch means actuated by said actuating element having on and off states corresponding to said positions, pressure responsive motor means responsive to applied pressures biasing said actuating element in the one direction, displacement control means for controlling the displacement of said actuating element during a constantly increasing motive pressure applied to said motor means to provide a substantially null displacement for a substantial intermediate pressure range between upper and lower pressure ranges, said displacement control means including first and second series connected spring means for biasing said actuating element in the off direction and a coupling member connecting said first and second spring means, anchor means for holding one end of said first spring means in a relatively fixed position, means attaching one end of said second spring means to said actuating element, stationary first abutment means for arresting movement of said coupling member after a predetermined displacement at a position corresponding to a predetermined lower pressure applied to said motor means, second abutment means attached to and carried by said actuating element for engagement with said coupling member when said applied pressure is lower than a predetermined higher pressure applied to said motor means, said first and second abutment means being effective to prevent said first and second spring means from deforming during said intermediate pressure range.
Specification