Charging circuit for battery in thermostat with battery operated timer

• US 4,249,696 A
• Filed: 05/11/1979
• Issued: 02/10/1981
• Est. Priority Date: 05/11/1979
• Status: Expired due to Term

• Current Assignee: Emerson Electric Company
• Original Assignee: Emerson Electric Company
• Inventors: Donnelly, Donald E., Krump, Robert C.
• Primary Examiner(s): Wayner, William E.
• Application Number:
  US06/038,093
• Time in Patent Office: 641 Days
• Field of Search: 236/46 R, 165/12, 307/66, 337/302, 337/303, 320/51, 320/57
• US Class Current: 236/46.00R
• CPC Class Codes: G05D 23/1904 variable in time
• CPC Class Codes: G05D 23/275 with sensing element expanding, contracting, or fusing in response to changes of temperature

Abstract

A timer controlled space thermostat includes a battery operated timer and charging circuit means for continuously charging the battery. The charging circuit means includes a miniature transformer having two primary windings and one secondary winding wound on a single core. When a thermostat switch therein is closed to effect energizing of space conditioning apparatus, one of the primary windings induces a stepped-up voltage and stepped-down current in the secondary winding to effect charging the battery. When the thermostat switch is open, the other primary winding induces a stepped-down voltage and stepped-up current in the secondary winding to effect charging the battery.

Claims

1. An improved battery charging circuit means in a timer controlled space thermostat wherein the timer is connected to a rechargeable battery for continuous operation thereof, wherein the improved charging circuit means comprises:

a transformer including two primary windings and one secondary winding wound on a single iron core;

said secondary winding being connected in circuit with the battery for effecting charging of said battery when energized;

one of said primary windings being of low impedance and connected in series with a thermostat switch of the space thermostat and energized when said thermostat switch is closed to effect energizing of said secondary winding;

the other of said primary windings being of high impedance and connected in parallel with said thermostat switch and energized when said thermostat switch is open to effect energizing of said secondary winding;

controlled solid state switching means connected in series with said other of said primary windings; and

gating circuit means for said switching means connected in parallel with said thermostat switch;

said gating circuit means being energized to effect conduction of said switching means only when said thermostat switch is open.

2. In a timer controlled space thermostat,

thermostat switching means connected in series with a remote power source and remote space conditioning apparatus control means and effective to control energizing and de-energizing of said control means;

an electrical timer for periodically changing the temperature at which said switching means effects said energizing and de-energizing of said control means;

a rechargable battery connected to said timer;

charging circuit means for continuously charging said battery including a transformer having two primary windings and a secondary winding wound on a single iron core;

said secondary winding being connected in circuit with said battery;

one of said primary windings being connected in series with said switching means and being responsive to energizing thereof, when said switching means effects said energizing of said control means, to induce a stepped-up voltage and a stepped-down current flow in said secondary winding effective to charge said battery;

the other of said primary windings being connected in parallel with said switching means and being responsive to energizing thereof, when said switching means effects said de-energizing of said control means, to induce a stepped-down voltage and a stepped-up current flow in said secondary winding effective to charge said battery; and

said transformer being saturated at a low value of current flow through said one of said primary windings when said switching means effects said energizing of said control means.