Humidity and temperature responsive switch
First Claim
Patent Images
1. A temperature and humidity responsive switch comprising:
- a base member;
an elongated stationary member with one end attached to said base member and a second end supporting a contact;
an elongated bendable switch element having one end attached to said base member and a movable second end supporting a contact in alignment with the contact on said stationary member so as to cause engagement of said contacts when the second end of the switch element moves toward said stationary member during bending of the switch element;
said switch element having a laminated structure with a metal portion and a plastic portion bonded together in a manner so that differences in their respective coefficients of thermal expansion affect the position of the movable second end of said switch element with respect to said second end of the stationary member;
said elongated switch element being separated by slot means into side by side strip portions whose end portions adjacent said movable second end are joined and whose mid-portions are movable in the lateral direction with respect to one another;
at least one of said strip portions being shortened in length, thereby causing the middle of the remaining strip portion to bend laterally in one direction from the general plane of the switch element during a low range of ambient temperatures and to cause the contact on the movable second end of the switch element to be positioned away from the contact on said second end of said stationary member and subsequently causing the middle portion to pass through the plane of the switch element and to bend in an opposite lateral direction with increasing ambient temperatures due to the differences in thermal coefficients of the metal and plastic so as to cause the contact on the second end of the switch element to engage the contact on the stationary member in a rapid and positive manner.
0 Assignments
0 Petitions
Accused Products
Abstract
A humidity-biased temperature responsive switch for controlling an automobile air conditioning compressor which closes at a warmer ambient temperature when the humidity is low than when the humidity is greater. The switch includes a sensor element having a metal strip and a hygroscopic plastic strip laminated together so that the different thermal coefficients of expansion will cause the free end of a cantilever-mounted sensor to move a contact. Absorption of water from the ambient air causes the plastic to swell and elongate and resultantly moves the contact into a closed position at a lower temperature than when the humidity is low.
7 Citations
3 Claims
-
1. A temperature and humidity responsive switch comprising:
- a base member;
an elongated stationary member with one end attached to said base member and a second end supporting a contact;
an elongated bendable switch element having one end attached to said base member and a movable second end supporting a contact in alignment with the contact on said stationary member so as to cause engagement of said contacts when the second end of the switch element moves toward said stationary member during bending of the switch element;
said switch element having a laminated structure with a metal portion and a plastic portion bonded together in a manner so that differences in their respective coefficients of thermal expansion affect the position of the movable second end of said switch element with respect to said second end of the stationary member;
said elongated switch element being separated by slot means into side by side strip portions whose end portions adjacent said movable second end are joined and whose mid-portions are movable in the lateral direction with respect to one another;
at least one of said strip portions being shortened in length, thereby causing the middle of the remaining strip portion to bend laterally in one direction from the general plane of the switch element during a low range of ambient temperatures and to cause the contact on the movable second end of the switch element to be positioned away from the contact on said second end of said stationary member and subsequently causing the middle portion to pass through the plane of the switch element and to bend in an opposite lateral direction with increasing ambient temperatures due to the differences in thermal coefficients of the metal and plastic so as to cause the contact on the second end of the switch element to engage the contact on the stationary member in a rapid and positive manner.
- a base member;
-
2. A temperature and humidity responsive switch comprising:
- a base member;
an elongated stationary member with one end attached to said base member and a second end supporting a contact;
an elongated bendable switch element having one end attached to said base member and a movable second end supporting a contact in alignment with the contact on said stationary member so as to cause engagement of said contacts when the second end of the switch element moves toward said stationary member during bending of the switch element;
said switch element having a laminated structure with a metal portion and a plastic portion bonded together in a manner so that differences in their respective coefficients of thermal expansion affect the position of the movable second end of said switch element with respect to said second end of the stationary member;
said switch element having slots therethrough extending lengthwise, separating the midportion of said switch element into three strip portions;
the two outer strip portions being crimped to shorten their length, thereby causing the middle unshortened strip portion to bend laterally outwardly in one direction from the plane of the switch element during a low range of ambient temperatures to cause contact on the movable second end of the laminated switch element to be positioned away from the contact on said second end of the stationary member and subsequently causing the middle portion to pass through the plane of the switch element and bend in an opposite second direction with respect to the plane of the switch element with increasing ambient temperatures due to the differences in thermal expansion coefficients of the metal and plasitc so as to cause the contact on the second end of the switch element to engage the contact on the stationary member in a rapid and positive manner;
said plastic portion exhibiting hygroscopic properties which cause said plastic portion to swell and elongate when moisture is obsorbed due to increasing humidity, whereby the position of said movable second end of said switch element with respect to said stationary member changes in response to humidity changes;
said metal portion having a lower coefficient of thermal expansion than said plastic portion and being located between said stationary member and said plastic portion to cause movement of the second end of the laminated switch element and resultant engagement of the contacts with increasing ambient temperatures;
the outer placement of said plastic portion of the laminated switch element with respect to said stationary member causing the contact engagement to take place at a lower ambient temperature at a relatively high humidity due to the swelling and elongation of said hygroscopic plastic.
- a base member;
-
3. A temperature and humidity responsive switch comprising:
- base support means for an elongated stationary member, one end of which is attached to said support, the second end of which is spaced from the plane of said support and has an electrical contact thereon;
a laminated switch element, one end of which is supported by said base means, the remainder extending therefrom in substantial parallelism with said stationary member;
said laminated switch element having a metal portion bonded to a hygroscopic plastic portion to produce a unitary switch element including diverse materials with different thermal coefficients of expansion;
an electrical contact on the second end of said laminated switch element and oriented with respect to the electrical contact on said stationary member so that the contacts engage when the laminated element bends and places the switch in a closed operative mode;
said laminated switch element being separated into three independently movable portions by slots extending in a lengthwise direction;
the two outer portions being crimped to reduce their length and to cause the other portion to curve from the plane of said laminated element whereby the difference in coefficients of expansion between the metal and the plastic causes rapid movement of the second end of the laminated element to engage the contacts in response to an increase in ambient temperature while simultaneously the absorption of moisture by the plastic portion of the laminated element due to humidity increases, biases the second end of the laminated element toward the fixed contact so that the switch will close at a lower ambient temperature when the humidity is high than when the humidity is low.
- base support means for an elongated stationary member, one end of which is attached to said support, the second end of which is spaced from the plane of said support and has an electrical contact thereon;
Specification