Dual speed controller for attic ventilator

• US 5,049,801 A
• Filed: 03/09/1990
• Issued: 09/17/1991
• Est. Priority Date: 10/20/1982
• Status: Expired due to Fees

• Current Assignee: Clark United Corporation
• Original Assignee: Clark United Corporation
• Inventors: Potter, Paul S.
• Primary Examiner(s): Ip, Paul
• Application Number:
  US07/491,168
• Time in Patent Office: 557 Days
• Field of Search: 318/726-832, 236/47, 236/49.3, 236/67, 236/78 B, 236/78 C, 236/79, 236/80 C, 236/91 F, 236/101 B, 236/DIG. 9, 126/419, 126/422, 126/436, 98/42.04, 98/42.07, 98/116
• US Class Current: 318/785
• CPC Class Codes: F24F 11/0001 for ventilation F24F11/30 takes precedence
• CPC Class Codes: H02P 25/04 Single phase motors, e.g. capacitor motors
• CPC Class Codes: Y10S 236/09 Fan control

Abstract

A controller for a dual speed induction motor selectively applies operating power to the low speed motor terminal or the high speed motor terminal according to the open circuit/closed circuit condition of a low temperature thermostat and a high temperature thermostat. For low speed operation, operating power is conditionally applied to the low speed motor terminal through the low temperature thermostat and through the normally closed circuit of a single pole, double throw switch. For high speed operation, operating power is conditionally applied to the high speed motor terminal through the high temperature thermostat and the normally open circuit of the single pole, double throw switch. The operating position of the single pole, double throw switch is determined by a solenoid which is connected in series circuit relation with the high temperature thermostat.

Claims

1. A speed control circuit for applying electrical power from a power distribution circuit of the type having hot and return power conductors to a multiple speed induction motor of the type including an armature winding having a high speed power terminal, a low speed power terminal and a return power terminal, said controller circuit comprising, in combination:

a first-normally open thermostat having an unswitched power terminal, a switched power terminal and a temperature responsive switch element adapted to make a closed circuit between said switched and unswitched power terminals at a first temperature level;

a second normally open thermostat having a switched power terminal, an unswitched power terminal and a temperature responsive switch element adapted to make a closed circuit between said switched and unswitched power terminals at a second temperature level;

a single pole, double throw switch assembly, said switch assembly having an unswitched power terminal, normally closed and normally open power terminals and a movable switch element connected to said unswitched power terminal;

a solenoid including a control winding having first and second power terminals and control linkage mechanically coupled to said movable switch element for moving said switch element from electrical contacting engagement with said normally closed power terminal to said normally open power terminal in response to the application of electrical power to said control winding;

the switched power terminal of said first thermostat being adapted for connection to the low speed power terminal of said motor, the unswitched power terminal of said first thermostat being connected to the normally closed power terminal of said switch assembly, the switched power terminal of said second thermostat being electrically connected to the first power terminal of said solenoid control winding, the unswitched power terminal of said second thermostat being connected to the unswitched power terminal of said switch assembly, the second power terminal of said solenoid winding being adapted for connection to the return power terminal of said induction motor and to the return power conductor of said power source, the normally open power terminal of said switch assembly being adapted for connection to the high speed power terminal of said induction motor, and the unswitched power terminal of said switch assembly being adapted for electrical connection to the hot power conductor of said power source.

2. A control circuit for applying electrical power from hot and return power distribution conductors to a dual speed induction motor comprising:

a low speed power output terminal, a high speed power output terminal and a power return output terminal;

a hot power input terminal and a power return input terminal;

a first normally open thermostat switch having a temperature responsive switch element which is adapted to close in response to a first temperature level;

a second normally open thermostat switch having a temperature responsive element which is adapted to close in reponse to a second temperature level;

a single pole, double throw switch having an unswitched power input terminal, a normally closed, switched power output terminal, a normally open, switched power output terminal and a movable switch element electrically connected to said unswitched power input terminal;

a solenoid including a control winding having first and second power terminals for conducting electrical current from said power source, said solenoid having linkage mechanically coupled to said movable switch element for moving said switch element from contacting engagement with sad normally closed power output terminal to said normally open power output terminal in response to the application of electrical power to said control winding; and

,

said first normally open thermostat having switched and unswitched power terminals connected in electrical series circuit relation with the low speed power output terminal and the normally closed, switched power output terminal of said switch assembly, respectively, said second normally open thermostat switch having switched and unswitched power terminals connected in electrical series relation with the first power terminal of said solenoid control winding and the unswitched power input terminal of said switch assembly respectively, the second power terminal of said solenoid winding being connected to the power input and power output return terminals, the normally open power output terminal of said switch assembly being connected to said high speed power output terminal, and the unswitched power terminal of said single pole, double throw switch being connected to the hot power input terminal.

3. A controller for selectively applying electrical power from a power distribution circuit to a multiple speed induction motor of the type including an armature winding having a high speed power terminal, a low speed power terminal and a common return power terminal, said control circuit comprising a first normally open thermostat switch adapted to close in response to a first sensed temperature level;

a second normally open thermostat switch which is adapted to close in response to a second sensed temperature level;

a single pole, double throw selector switch having a normally closed switching circuit and a normally open switching circuit, and a solenoid mechanically coupled to said selector switch for changing the operating mode of said selector switch from said normally closed circuit condition to the normally open circuit condition in response to the application of power to said solenoid, a low temp thermostat being coupled to the normally closed circuit of said selector switch for conditionally applying operating power to the low speed power terminal of said induction motor when said low temp thermostat is in closed circuit condition and a high temp thermostat is in open circuit condition, and said high temp thermostat being coupled in series with said solenoid for applying operating power to said solenoid when said high temp thermostat is in the closed circuit condition.

4. An attic ventilator system comprising, in combination:

an induction motor having an armature winding, a rotor magnetically coupled to said armature winding, a fan blade mechanically coupled to said rotor, said armature winding having a low speed input power terminal, a high speed input power terminal and a common return power terminal;

a high temp normally open thermostat switch having a temperature responsive switch element which is adapted to close in response to a first temperature level;

a low temp normally open thermostat switch having a temperature responsive element which is adapted to close in response to a second temperature level;

a single pole, double throw switch having an unswitched power terminal, a normally closed, switched power terminal, a normally open, switched power terminal and a movable switch element electrically connected to said unswitched power terminal;

a solenoid including a control winding having first and second power terminals for conducting electrical current from a hot power conductor to a common return power conductor, said solenoid having mechanical linkage coupled to said movable switch element for moving said switch element from contacting engagement with said normally closed power terminal to contacting engagement with said normally open power terminal in response to the application of electrical power to said control winding; and

,

said low temperature, normally open thermostat having switched and unswitched power terminals connected in electrical series circuit relation between the normally closed, switched power terminal of said selector switch assembly and the low speed power output terminal, said high temp thermostat switch having switched and unswitched power terminals connected in electrical series relation between the normally open power terminal of said selector switch assembly and the first power terminal of said solenoid control winding, the second power terminal of said solenoid winding being connected to the common power input and output return terminals, the normally open power terminal of said switch assembly being connected to said high speed power output terminal, and the unswitched power terminal of the selector switch being connected to the hot power conductor.

5. A controller for selectively applying electrical power from a power distribution circuit to a multiple speed induction motor of the type including an armature winding having a high speed power input terminal, a low speed power input terminal and a common return power terminal, said controller comprising, in combination:

a first detector for sensing the magnitude of a first operating condition;

a first normally open switch coupled to said first detector, said first switch being adapted to close in response to the detection of a first threshold level;

a second detector for sensing the magnitude of a second operating condition;

a second normally open switch coupled to said second detector, said second switch being adapted to close in response to the detection of a second threshold level;

a single pole, double throw selector switch having a normally closed switching circuit and a normally open switching circuit, and a switch mode actuator coupled to said selector switch for changing the operating mode of said selector switch from the normally closed circuit condition to the normally open circuit condition in response to the application of power to said switch mode actuator; and

,

said first switch being coupled to the normally closed circuit of said selector switch for conditionally applying operating power to the low speed power input terminal of said induction motor when said first switch is in closed circuit condition and said second switch is in open circuit condition, and said second switch being coupled in series with said switch mode actuator for applying operating power to said switch mode actuator when said second switch is in the closed circuit condition.