Furnace blower speed control

• US 3,912,162 A
• Filed: 12/07/1973
• Issued: 10/14/1975
• Est. Priority Date: 12/07/1973
• Status: Expired due to Term

• Current Assignee: Frederick T. Bauer, Ronald E. Holkeboer
• Original Assignee: Frederick T. Bauer, Ronald E. Holkeboer
• Inventors: Bauer, Frederick T., Holkeboer, Ronald E.
• Primary Examiner(s): Favors, Edward G.
• Application Number:
  US05/422,729
• Time in Patent Office: 676 Days
• Field of Search: 236/11,9 318/11,331,334
• US Class Current: 236/11
• CPC Class Codes: F23N 1/022 using electronic means
• CPC Class Codes: F23N 2227/04 Prepurge
• CPC Class Codes: F23N 2227/06 Postpurge
• CPC Class Codes: F23N 2233/08 with variable speed
• CPC Class Codes: G05D 23/19 characterised by the use of electric means G05D23/1393 takes precedence
• CPC Class Codes: Y10S 388/934 Thermal condition

Abstract

A furnace blower speed control system adapted to vary the speed of a furnace blower with respect to time, the system including solid state means energizable to effect a delayed start of the blower at a low speed after a predetermined time following furnace burner ignition and to gradually increase the speed of the blower as the furnace temperature rises until full blower speed is reached. The system is also operable to maintain the full blower speed for a predetermined time after the burner is extinguished and thereafter gradually decrease the speed of the blower as the furnace cools down.

Claims

1. In a speed control system adapted to vary the speed of an electric motor as a function of time, the combination including solid state means energizable after a predetermined time delay to start said motor at a low speed and to gradually increase the speed of said motor until full motor speed is reached, said system including means operable to delay the start of said motor, means operable to maintain said motor at full speed and means operable to decrease the speed of said motor gradually to a stopped condition, said solid state means including a Zener diode and a timing capacitor, said Zener diode being effective to increase the speed of said motor by charging said timing capacitor.

2. In a speed control system adapted to vary the speed of an electric motor as a function of time, the combination including solid state means energizable after a predetermined time delay to start said motor at a low speed and to gradually increase the speed of said motor until full motor speed is reached, said system including means operable to delay the start of said motor, means operable to maintain said motor at full speed, and means operable to decrease the speed of said motor gradually to a stopped condition, said system including means comprising a pair of programmable unijunction transistors energizable to stop said motor to a speed greater than the starting speed of said motor.

3. The combination as set forth in claim 2 including means for adjusting the starting speed of said motor.

4. The combination as set forth in claim 2 including means for adjusting the stopping speed of said motor.

5. A furnace blower speed control system adapted to vary the speed of a furnace blower motor as a function of time and operable in conjunction with a furnace burner, said system comprising, in combination, solid state means energizable to start said motor at a low speed at a predetermined time after said burner ignites and to gradually increase the speed of said motor until full motor speed is reached, and means for gradually decreasing the speed of said motor commencing at a predetermined time after said burner is extinguished, said solid state means including a triac, a programmable unijunction transistor, a Zener diode and a timing capacitor, said programmable unijunction transistor controlling the energization of said triac, said Zener diode controlling the charging of said timing capacitor.

6. The combination as set forth in claim 5 wherein said system includes means comprising a pair of programmable unijunction transistors energizable to stop said motor at a speed greater than the starting speed of said motor.

7. The combination as set forth in claim 6 including means for adjusting the starting speed of said motor.

8. The combination as set forth in claim 6 including means for adjusting the stopping speed of said motor.

9. A furnace blower speed control system adapted to vary the speed of a furnace blower motor as a function of time and operable in conjunction with an ignitable furnace burner, said system comprising, in combination, solid state means energizable to start said motor at a relatively low speed after a predetermined time following ignition of said burner, means in said system for gradually increasing the speed of said motor until full motor speed is reached, and means operable to maintain said motor at full speed for a predetermined time after said burner is extinguished and thereafter to gradually decrease the speed of said motor to a stopped condition, said solid state means including a triac, a programmable unijunction transistor, a Zener diode and a timing capacitor, said programmable unijunction transistor controlling the energization of said triac, said Zener diode controlling the charging of said timing capacitor, means comprising a pair of programmable unijunction transistors energizable to stop said motor at a speed greater than the starting speed of said motor, and means for adjusting the stopping speed of said motor.

10. In a furnace blower speed control system adapted to vary the speed of a furnace blower motor as a function of time and operable in conjunction with an ignitable furnace burner adapted to be connected to a main line source of AC current, a low voltage control circuit including motor control means energizable to start said motor at a low speed in response to ignition of said burner and to gradually increase the speed of said motor until full motor speed is reached, means in said circuit for maintaining said motor at full speed while said burner is ignited, and means in said circuit for gradually decreasing the speed of said motor to a stopped condition after said burner is extinguished.

11. The combination as set forth in claim 10 including means effective to delay the energization of said motor control means for a predetermined time following ignition of said burner.

12. The combination as set forth in claim 10 including means effective to delay the deenergization of said motor for a predetermined time following extinguishment of said burner.

13. The combination as set forth in claim 10 including means effective to delay the energization of said motor control means for a predetermined time following ignition of said burner, and means effective to delay the deenergization of said motor control means for a predetermined time following extinguishment of said burner.

14. The combination as set forth in claim 10 wherein said motor control means includes a triac and a timing capacitor, means including a Zener diode effective to gradually increase the speed of said motor by charging said timing capacitor, a pair of programmable unijunction transistors energizable to stop said motor at a speed greater than the starting speed of said motor, means for adjusting the starting speed of said motor, and means for adjusting the stopping speed of said motor.