Direct mount pressure control with a field adjustable trip point and reset point
AssigneeJohnson Service Company
InventorRobert Doherty
Life of this patent
Estimating the term…
Abstract
A pressure control for use in applications such as refrigeration, air conditioning and ice generating machinery includes a highly accurate snap acting switch, field adjustable trip points and reset points and a reference scale. The trip point is adjusted by means of an adjustment screw, while the reset point is adjusted by changing the differential, or the difference between the trip point and reset point. The differential is adjusted by adjusting the amount of "lost motion" within the control by employing an actuator which includes a cam surface and means for changing the position of the cam surface.
Claims19
A pressure switch comprising:
- a body having an opening communicating with the pressure to be sensed;
- a blade within the body being normally biased to a first position;
- an actuator within the body for moving the blade from its first to a second position when the sensed pressure exceeds a first preselected level;
- means for changing the first preselected level;
- means for returning the blade to its first position from the second position when the sensed pressure falls below a second preset level;
- a cam surface on the actuator, the returning means contacting the cam surface;
- and
- means for moving the cam surface for changing the second preselected level.
A pressure switch having a cylindrical housing and an opening to the pressure to be sensed, a resilient diaphragm adjacent the opening, an actuator movable in response to the sensed pressure, an elongate switch blade with a first end normally biased to a first position, the first end having contacts on opposed sides, the blade being movable to a second position when the actuator moves in response to a sensed pressure above a first predetermined level, terminals for contacting one of the blade contacts when the blade is in each of its first and second positions, and a main spring in the body, the switch further comprising:
- means for varying the pressure of the main spring against the diaphragm;
- a blade return spring having a sliding portion passing through the blade and biased for contacting the actuator, and an abutment on the portion;
- cam means on the actuator for receiving an end of the portion of the blade return spring and for varying the penetration of the portion and the abutment dependent upon the position of the cam surface;
- and
- means for moving the cam surface to adjust the relationship of the portion end along the cam surface.
Dependencies are inferred from the claim text.