Humidifier control system

Claim 2

In a humidifier control system, an a.c. power source, circuit connections including a signal controlled solid state switch connecting an electrically operated humidifier across said power source, a voltage step-down transformer having a primary winding connected across said power source and having a secondary winding forming the power source of a low voltage circuit which includes in series arrangement therewith a humidity responsive switch and a filament lamp, and gating means for said solid state switch including a light sensitive cell looking at said filament lamp and operative to effect conduction of said switch when said lamp filament becomes sufficiently heated upon closure of said humidity responsive switch, means responsive to outdoor temperature and operative in response to decreasing temperature below a predetermined outdoor temperature to modify the operation of said humidity responsive switching means in a manner to progressively reduce the humidity in a space, said means comprising a heat responsive actuator operatively connected to said humidity responsive switch, an electrical resistance heater operative to heat said actuator, and a second signal controlled solid state switch series connected across said transformer secondary winding, and temperature variable gating means including a thermistor positioned outdoors for controlling conduction of said second solid state switch thereby to control current flow through said resistance heater.

Claim 3

The humidifier control system claimed in claim 1 in which said gating means for said second solid state switch is operative to fire said switch progressively later during each conductive half cycle thereof as the outdoor temperature drops, and said gating means further including a capacitor series connected with said thermistor across said solid state switch, and a voltage breakdown switch connected to the control electrode of said switch and to a point between said thermistor and said capacitor.

Claim 4

The humidifier control system claimed in claim 1 which comprises three units adapted to be positioned remote from each other and connected only by electrical leads: a first space humidistat unit comprising a casing housing said humidity responsive switching means, said heat responsive actuator, said resistance heater and the control circuit therefor except said thermistor; a second outdoor temperature sensing unit comprising a thermistor and a casing housing it; and a third transformer relay unit comprising a casing housing said voltage stepdown transformer, said solid state switchiNg means, said filament lamp, and said light sensitive cell.

Claim 5

In a space humidistat, a switch comprising a pivoted member, a pair of resilient switch blades connected at one end to said member and extending therefrom in spaced relationship to free ends, a contact carried by each of said blades and normally in spaced relationship, a humidity responsive element connected at one end to said pivoted member and fixed at its other end and responsive to decreasing relative humidity to contract and rotate said member in one direction, abutment means engaging one of said blades near its free end and opposing rotation of said member in said one direction thereby causing flexing of said blade and the movement of the contact thereon toward the other contact, manual means for adjustably positioning said abutment means thereby to vary the control point at which said contacts will be closed in response to decreasing humidity, and means including a bimetal strip forming an operative connection between said manual means and said abutment means operative when variably heated to vary the position of said abutment means thereby to vary said control point, an electrical resistance heater operative to heat said bimetal strip, an electrical circuit for energizing said heater comprising said heater, a power source, and a signal controlled solid state switch, and gating means for said switch including a thermistor adapted to be positioned so as to be responsive to outdoor temperature and operative to effect the conduction angle of said switch so as to progressively reduce the current flow through said heater as the outdoor temperature drops.

Claim 6

In a space humidistat, a switch comprising a pivoted member, a pair of resilient switch blades connected at one end to said member and extending therefrom in spaced relationship to free ends, a contact carried by each of said blades and normally in spaced relationship, a humidity responsive element connected at one end to said pivoted member and fixed at its other end and responsive to decreasing relative humidity to contract and rotate said member in one direction, abutment means engaging one of said blades near its free end and opposing rotation of said member in said one direction thereby causing flexing of said blade and the movement of the contact thereon toward the other contact, manual means for adjustably positioning said abutment means thereby to vary the control point at which said contacts will be closed in response to decreasing humidity, and means including a bimetal strip forming an operative connection between said manual means and said abutment means operative when variably heated to vary the position of said abutment means thereby to vary said control point, an electrical resistance heater operative to heat said bimetal strip, an electrical circuit for energizing said heater comprising said heater, a power source, and a signal controlled solid state switch, and gating means for said switch including a thermistor adapted to be positioned so as to be responsive to outdoor temperature and operative to effect the conduction angle of said switch so as to progressively reduce the current flow through said heater as the outdoor temperature drops.

Claim 7

In a space humidistat, a switch comprising a pivoted member, a pair of resilient switch blades connected at one end to said member and extending therefrom in spaced relationship to free ends, a contact carried by each of said blades and normally in spaced relationship, a humidity responsive element connected at one end to said pivoted member and at its other end to the free end of a bimetal strip which has its other end fixed, the element being responsive to decreasing relative humidity, to contract and rotate said member in one direction. abutment means engaging one of said blades near its free end and opposing rotation of said member in said one direction thereby causing flexing of said blade and moving the contact thereon toward the other contact, manual means for adjusting said abutment means whereby the control point at which said contacts will close upon decreasing relative humidity may be varied, and means for automatically varying the control point in accordance with outdoor temperature comprising an electrical resistance heater operative to variably heat said bimetal strip thereby to vary the tension in said humidity responsive element, electrical circuit means comprising said resistance heater, a power source, and signal controlled solid state switching means, and gating means for said switching means including a thermistor responsive to outdoor temperature and operative to reduce the conduction angle of said switching means as the outdoor temperature decreases.

Claim 8

In a space humidistat, a switch comprising a pivoted member, a pair of resilient switch blades connected at one end to said member and extending therefrom in spaced relationship to free ends, a contact carried by each of said blades and normally in spaced relationship, a humidity responsive element connected at one end to said pivoted member and at its other end to the free end of a bimetal strip which has its other end fixed, the element being responsive to decreasing relative humidity, to contract and rotate said member in one direction. abutment means engaging one of said blades near its free end and opposing rotation of said member in said one direction thereby causing flexing of said blade and moving the contact thereon toward the other contact, manual means for adjusting said abutment means whereby the control point at which said contacts will close upon decreasing relative humidity may be varied, and means for automatically varying the control point in accordance with outdoor temperature comprising an electrical resistance heater operative to variably heat said bimetal strip thereby to vary the tension in said humidity responsive element, electrical circuit means comprising said resistance heater, a power source, and signal controlled solid state switching means, and gating means for said switching means including a thermistor responsive to outdoor temperature and operative to reduce the conduction angle of said switching means as the outdoor temperature decreases.

Claim 9

The space humidistat claimed in claim 5 in which said thermistor is operative to effect maximum conduction of said solid state switch at all temperatures above a predetermined outdoor temperature and to effect a progressive reduction in the conduction thereof to zero conduction as the outdoor temperature decreases therefrom to a lower predetermined outdoor temperature.