Ventilation fan control

• US 5,364,026 A
• Filed: 11/14/1991
• Issued: 11/15/1994
• Est. Priority Date: 11/14/1991
• Status: Expired due to Fees

• Current Assignee: Control Resources, Inc.
• Original Assignee: Control Resources, Inc.
• Inventors: Kundert, Warren R.
• Primary Examiner(s): Ford, John K.
• Application Number:
  US07/792,236
• Time in Patent Office: 1,097 Days
• Field of Search: 236/49.3, 236/78 B, 236/78 D, 236/DIG. 9, 388/934, 388/910, 388/916, 318/471, 318/472, 318/473, 417/32
• US Class Current: 236/49.3
• CPC Class Codes: F24F 11/0001 for ventilation F24F11/30 takes precedence
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/46 Improving electric energy efficiency or saving
• CPC Class Codes: F24F 11/76 by means responsive to temperature, e.g. bimetal springs
• CPC Class Codes: F24F 11/77 by controlling the speed of ventilators
• CPC Class Codes: F24F 11/88 Electrical aspects, e.g. circuits
• CPC Class Codes: F24F 2011/0002 for admittance of outside air
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: F24F 2110/12 of the outside air
• CPC Class Codes: F24F 7/06 with forced air circulation, e.g. by fan positioning of a ventilator in or against a conduit
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
• CPC Class Codes: Y10S 236/09 Fan control
• CPC Class Codes: Y10S 388/91 Operational/differential amplifier
• CPC Class Codes: Y10S 388/916 Threshold circuit
• CPC Class Codes: Y10S 388/934 Thermal condition

Abstract

The residential structure ventilating apparatus disclosed herein employs a variable speed exhaust fan. The speed is responsive to a sensor which detects air temperature at the exhaust port. The fan is energized when the sensed air temperature rises above a first preselectable temperature and the external environmental air is cooler that the air at the exhaust port. The fan speed is increased progressively from about one-half full speed at the preselected turn on temperature to full speed at a predetermined higher temperature. The fan is turned off when the exhaust port temperature falls below a second preselected temperature, lower than the first preselected temperature or when the external environmental temperature rises above the inside temperature, the fan speed being essentially constant between the first and second preselected temperatures.

Claims

1. Apparatus for ventilating a structure comprising:

a variable speed exhaust fan mountable in an exhaust port in the structure, said structure permitting the admission of external environmental air;

means including a triggerable semiconductor switching device for energizing said fan from a.c. supply means;

means for sensing air temperature at said exhaust port;

first control means including a comparator responsive to said sensing means and including analog feedback providing hysteresis for enabling triggering of said switching device when the sensed air temperature rises above a first preselectable temperature and for disabling triggering of said switching device when the sensed air temperature falls below a second preselected temperature lower than said first temperature; and

second control means for varying the phase angle of triggering of said switching device responsive to said sensing means for varying the speed of said fan for sensed air temperatures between said first temperature and a third preselectable temperature, said fan speed increasing progressively from about one-half full speed at said first temperature to full speed at said third temperature, said fan speed being essentially constant between said first and second temperatures.

2. Apparatus for ventilating a structure comprising:

3. a variable speed exhaust fan mountable in an exhaust port in the structure, said structure permitting the admission of external environmental air;

means including a triggerable semiconductor switching device for energizing said fan from a.c. suppy means;

first sensing means for sensing air temperature at said exhaust port;

second sensing means for sensing the temperature of external environmental air;

first control means including a comparator responsive to said sensing means and including analog feedback providing hysteresis for enabling triggering of said switching device when

A) the sensed air temperature rises above a first preselectable temperature and

B) the external environmental air temperature is below the air temperature at said exhaust port and

for disabling triggering of said switching device when the sensed air temperature falls below a second preselected temperature lower than said first temperature; and

second control means for varying the phase angle of triggering of said switching device responsive to said sensing means for varying the speed of said fan for sensed air temperatures between said first temperature and a third preselectable temperature, said fan speed increasing progressively from about one-half full speed at said first temperature to full speed at said third temperature, said fan speed being essentially constant between said first and second temperatures.

4. Apparatus for ventilating a structure comprising:

5. a variable speed exhaust fan mountable in an exhaust port in the structure, said structure permitting the admission of external environmental air;

means including a triggerable semiconductor switching device for energizing said fan from a.c. suppy means;

first sensing means for sensing air temperature at said exhaust port;

second sensing means for sensing the temperature of external environmental air;

first control means including a comparator responsive to said sensing means and including analog feedback providing hysteresis for enabling triggering of said switching device when

A) the sensed air temperature rises above a first preselectable temperature and

B) the external environmental air temperature is below the air temperature at said exhaust port and

for disabling energization of said fan when the sensed air temperature falls below a second preselected temperature lower than said first temperature or when outside environmental air temperature rises above inside air temperature by a preselected amount; and

second control means for varying the phase angle of triggering of said switching device responsive to said sensing means for varying the speed of said fan for sensed air temperatures between said first temperature and a third preselectable temperature, said fan speed increasing progressively from about one-half full speed at said first temperature to full speed at said third temperature, said fan speed being essentially constant between said first and second temperatures.

6. Apparatus for ventilating a structure comprising:

an a.c. motor powered variable speed exhaust fan mountable in an exhaust port in the structure, said structure permitting the admission of external environmental air;

circuit means including a triggerable semiconductor switching device for selectively energizing the fan motor from a.c. supply leads;

first sensing means for sensing air temperature at said exhaust port;

second sensing means for sensing the temperature of external environmental air;

first control means including at least one comparator circuit means interconnected with said first and second sensing means for enabling triggering of said switching device to effect energization of said fan when

A) the sensed air temperature rises above a first preselectable temperature and

B) the external environmental air temperature is below the air temperature at said exhaust port and said comparator circuit means includes analog feedback providing hysteresis for disabling energization of said fan by disabling triggering of said switching device when the sensed air temperature falls below a second preselected temperature lower than said first temperature; and

second control means responsive to said first sensing means for controlling the phase angle of triggering of said semiconductor switching device for varying the speed of said fan for sensed air temperatures between said first temperature and a third preselectable temperature, said fan speed increasing progressively from about one-half full speed at said first temperature to full speed at said third temperature, said fan speed being essentially constant between said first and second temperatures.