Method and circuit for timing chemical dispenser operation

• US 4,676,403 A
• Filed: 06/13/1986
• Issued: 06/30/1987
• Est. Priority Date: 09/28/1984
• Status: Expired due to Fees

• Current Assignee: Autotrol Corp. (GE Aerospace)
• Original Assignee: Autotrol Corp. (GE Aerospace)
• Inventors: Goudy, Paul R. Jr., Newman, Ronald E., Voigt, James R.
• Primary Examiner(s): Skaggs, H. Grant
• Application Number:
  US06/873,880
• Time in Patent Office: 382 Days
• Field of Search: 222/1, 222/641, 222/642, 222/643, 222/644-646, 222/52, 222/54, 221/1, 221/9, 221/13, 221/15, 377/16, 377/20, 377/6, 328/129.1, 137/624.13-624.15
• US Class Current: 222/54
• CPC Class Codes: H03K 17/292 in thyristor, unijunction transistor or programmable unijunction transistor switches
• CPC Class Codes: H03K 17/735 Switching arrangements with several input- or output-terminals, e.g. multiplexers, distributors H03K17/722 takes precedence; logic circuits H03K19/00; code converters H03M5/00, H03M7/00
• CPC Class Codes: H05B 47/16 by timing means
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

In a method and a circuit for controlling an amount of pelletized material that is dispensed from a pellet dispenser, the dispenser is driven at the same speed during each one of a plurality of pellet dispensing cycles. The frequency of dispenser operation is varied by varying the time interval between pellet dispensing cycles. The circuit includes two timers, an OFF timer which is connected to a counter that counts the number of "off" timing signals in each "off" period and an ON timer that receives a triggering signal from the counter when the "off" period is completed. A switch is connected to the counter to select this number of "off" timing signals. The "off" time period can also be altered by altering the time base of the OFF timer. This is accomplished with a resistance circuit that is connected to a timing circuit for the OFF timer, through either a user-controlled timer or a temperature-responsive switch.

Claims

1. A method for providing a constant rate at which dry chemical material is dispensed from a chemical dispenser, the method comprising:

driving the chemical dispenser at the same speed and for the same time during each one of a plurality of dispensing cycles during a treatment period;

counting a preset number of electrical timing signals that define a first off cycle for the dispenser, and upon reaching the present number, generating a signal to drive the dispenser through a first dispensing cycle;

in response to completion of the first dispensing cycle, counting the present number of electrical timing signals a second time to define a second off cycle for the dispenser of like duration to the first off cycle, and upon reaching the preset number, generating a signal to drive the dispenser through a second dispensing cycle; and

varying the duration of off cycles from one treatment period to another treatment period by varying the time interval over which the electrical timing signals are counted for each one of the first and second off cycles.

2. The method of claim 1, wherein the duration of off cycles is varied by selecting a different present number of electrical timing signals that are counted to measure each one of the first and second off cycles.

3. The method of claim 1, wherein the duration of off cycles is varied by varying the time base associated with the preset number of electrical timing signals that are counted to measure each one of the first and second off cycles.

4. Apparatus for selecting one of a plurality of constant rates at which dry chemical is emitted from a dispenser over a treatment period that includes a plurality of dispensing cycles, the apparatus comprising:

drive means for driving the dispenser at the same speed during each dispensing cycle;

switch means for turning the drive means on and off;

means for generating first triggering signals;

first timer means responsive to the first triggering signals to generate sequences of first timing signals during respective "off" periods for the dispenser;

counter means for receiving and relating the sequences of first timing signals to respective second triggering signals according to a user-selected count that determines the duration of each "off" period and a selected constant rate of dispensing cycles;

second timer means responsive to the second triggering signals to generate corresponding second timing signals to the switch means to cause the driving of the dispenser for respective dispensing cycles, the second timer means being further responsive at the end of each dispensing cycle to signal the first timer means to start generating a next sequence of first timing signals for a next "off" period.

5. The apparatus of claim 4, further comprising:

first switch means coupled to the counter means to allow a user to change the count that determines the duration of each "off" period of the dispenser.

6. Apparatus for providing two rates at which dry chemical is dispensed from a dispenser during a treatment period that includes a plurality of dispensing cycles, the apparatus comprising:

drive means for driving the dispenser at the same speed during each dispensing cycle;

first switch means for turning the drive means on and off;

means for generating first triggering signals;

first timer means responsive to the first triggering signals to generate squences of first timing signals during respective "off" periods for the dispenser,

wherein the first timer means includes an RC timing circuit that controls a timing period between first timing signals;

counter means for receiving and relating sequences of first timing signals to respective second triggering signals according to a user-selected count that determines the duration of each "off" period and a rate for the plurality of dispensing cycles;

second timer means responsive to the second triggering signals to generate corresponding second timing signals to the switch means to cause the driving of the dispenser for respective dispensing cycles;

resistance means;

second switch means for connection of the resistance means in the RC timing circuit of the first timing means; and

means for actuating the second switch means to change the timing period provided by the RC timing circuit and to change from a first rate for the plurality of dispensing cycles to a second rate for the plurality of dispensing cycles, said means deactuating the second switch means after an interval within the treatment period to resume the first rate for the plurality of dispensing cycles.

7. The apparatus of claim 6, wherein the means for actuating the second switch means to change from the first rate to the second rate is a third timer means for deactuating the second switch means after a timed interval to resume the first rate for the plurality of dispensing cycles.

8. The apparatus of claim 6, wherein the means for actuating the second switch means to change from the first rate to the second rate is a temperature responsive means for actuating the second switch means at a predetermined temperature threshold.