Claims
- 1. In a gas monitoring instrument having an electrically powered motor for driving a pump to bring a sample of gas from a location being tested to a sensor for determining the presence of contaminants in the gas, a motor speed control comprising:
a) a pulse modulation control and drive operatively connected between a source of voltage and the motor for controlling application of voltage drive pulses to the motor; b) means operatively associated with the motor for sampling motor back-e.m.f. during intervals between motor drive pulses to provide an output indicative of actual motor speed; c) means operatively connected to the means for sampling back-e.m.f. to provide a digital signal output containing information on the actual motor speed; d) a microprocessor connected to the output of the means to provide a digital signal and connected in controlling relation to the pulse modulation control and drive for comparing the actual motor speed to a desired motor speed for controlling the operation of the pulse modulation control; and e) means for connecting the microprocessor to the means for sampling back-e.m.f. for determining the intervals between modulated motor drive pulses during which motor back-e.m.f. is sampled.
- 2. The motor speed control according to claim 1, wherein the means for connecting the microprocessor to the means for sampling back-e.m.f. causes sampling of motor back-e.m.f. at a rate lower than the pulse rate of the modulated motor drive pulses.
- 3. The motor speed control according to claim 1, wherein the microprocessor extends the interval between motor drive pulses during which back-e.m.f. is sampled to provide full recovery of the back-e.m.f. and sufficient sampling time.
- 4. In a gas monitoring instrument having an electrically powered motor for driving a pump to bring a sample of gas from a location being tested to a sensor for determining the presence of contaminants in the gas:
a) a pulse modulation control and drive operatively connected between a source of voltage and the motor for controlling application of voltage drive pulses to the motor; b) means operatively associated with the motor for sampling motor back-e.m.f. during intervals between motor drive pulses to provide an output indicative of actual motor speed which is indicative of pump flow rate; and c) a control operatively connected to the back-e.m.f. sampling means for determining the intervals between motor drive pulses during which motor back-e.m.f. is sampled to provide an indication of pump flow rate.
- 5. The apparatus according to claim 4, wherein the control causes sampling of motor back-e.m.f. at a rate lower than the pulse rate of motor drive pulses.
- 6. The apparatus according to claim 4, wherein the control extends the interval between motor drive pulses during which back-e.m.f. is sampled to provide full recovery of the back-e.m.f. and sufficient sampling time.
- 7. A method for monitoring the flow of gas in a gas monitoring instrument wherein a sample of gas is caused to flow from a location being tested to a sensor for determining the presence of contaminants in the gas, the method comprising:
a) providing pulse modulation of a motor driving a pump which causes the flow of gas in the instrument; b) sampling motor back-e.m.f. during intervals between motor drive pulses to provide an indication of motor speed to determine the rate of flow of gas through the instrument; and c) selecting the intervals between motor drive pulses during which motor back-e.m.f. is sampled.
- 8. The method according to claim 7, wherein motor back e.m.f. is sampled at a rate lower than the pulse rate of motor drive pulses.
- 9. The method according to claim 7, wherein the interval between motor drive pulses during which back-e.m.f. is sampled is extended to provide full recovery of the back-e.m.f. and sufficient sampling time.
- 10. The method according to claim 7, wherein the indication of motor speed obtained from sampling motor back-e.m.f. is utilized to control the pulse modulation to control the motor speed and the rate of gas flow through the instrument.
- 11. The method according to claim 10, wherein the indication of motor speed is compared to a desired motor speed to provide a difference signal to control the pulse modulation.
- 12. In a system having an electrically powered motor for driving a pump to bring a quantity of fluid from one location to another, a motor speed control comprising:
a) a pulse modulation control and drive operatively connected between a source of voltage and the motor for controlling application of voltage drive pulses to the motor; b) means operatively associated with the motor for sampling motor back-e.m.f. during intervals between motor drive pulses to provide an output indicative of actual motor speed; c) means operatively connected to the means for sampling back-e.m.f. to provide a digital signal output containing information on the actual motor speed; d) a microprocessor connected to the output of the means to provide a digital signal and connected in controlling relation to the pulse modulation control and drive for comparing the actual motor speed to a desired motor speed for controlling the operation of the pulse modulation control; and e) means for connecting the microprocessor to the means for sampling back-e.m.f. for determining the intervals between modulated motor drive pulses during which motor back-e.m.f. is sampled.
- 13. The motor speed control according to claim 12, wherein the means for connecting the microprocessor to the means for sampling back-e.m.f. causes sampling of motor back-e.m.f. at a rate lower than the pulse rate of motor drive pulses.
- 14. The meter speed control according to claim 12, wherein the microprocessor extends the interval between motor drive pulses during which back-e.m.f. is sampled to provide full recovery of the back-e.m.f. and sufficient sampling time.
- 15. In a system having an electrically powered motor for driving a pump to bring a quantity of fluid from one location to another:
a) a pulse modulation control and drive operatively connected between a source of voltage and the motor for controlling application of voltage drive pulses to the motor; b) means operatively associated with the motor for sampling motor back-e.m.f. during intervals between motor drive pulses to provide an output indicative of actual motor speed which is indicative of pump flow rate; and c) a control operatively connected to the back-e.m.f. sampling means for determining the intervals between motor drive pulses during which motor back-e.m.f. is sampled to provide an indication of pump flow rate.
- 16. The apparatus according to claim 15, wherein the control causes sampling of motor back-e.m.f. at a rate lower than the pulse rate motor drive pulses.
- 17. The apparatus according to claim 15, wherein the control extends the interval between motor drive pulses during which back-e.m.f. is sampled to provide full recovery of the back-e.m.f. and sufficient sampling time.
- 18. A method for monitoring the flow of fluid in a fluid monitoring system wherein a quantity of fluid is caused to flow from one location to another, the method comprising:
a) providing pulse modulation of a motor driving a pump which causes the flow of gas in the system; b) sampling motor back-e.m.f. during intervals between motor drive pulses to provide an indication of motor speed to determine the rate of flow of gas through the system; and c) selecting the intervals between motor drive pulses during which motor back-e.m.f. is sampled.
- 19. The method according to claim 18, wherein motor back-e.m.f. is sampled at a rate lower than the pulse rate of motor drive pulses.
- 20. The method according to claim 18, wherein the interval between motor drive pulses during which back-e.m.f. is sampled is extended to provide full recovery of the back-e.m.f. and sufficient sampling time.
- 21. The method according to claim 18, wherein the indication of motor speed obtained from sampling motor back-e.m.f. is utilized to control the pulse modulation to control the motor speed and the rate of fluid flow through the system.
- 22. The method according to claim 21, wherein the indication of motor speed is compared to a desired motor speed to provide a difference signal to control the pulse modulation.
- 23. A motor speed control comprising:
a) a pulse modulation control and drive for connection between a source of voltage and a motor for controlling application of motor drive pulses to the motor; b) means operatively associated with the motor for sampling motor back-e.m.f. during intervals between motor drive pulses to provide an output indicative of actual motor speed; c) means operatively connected to the means for sampling back-e.m.f. to provide a digital signal output containing information on the actual motor speed; d) a microprocessor connected to the output of the means to provide a digital signal and connected in controlling relation to the pulse modulation control for comparing the actual motor speed to a desired motor speed for controlling the operation of the pulse modulation control; and e) means for connecting the microprocessor to the means for sampling back-e.m.f. for determining the intervals between modulated motor drive pulses during which motor back-e.m.f. is sampled.
- 24. The motor speed control according to claim 23, wherein the means for connecting the microprocessor to the means for sampling back-e.m.f. causes sampling of motor back-e.m.f. at a rate lower than the pulse rate of the modulated motor drive pulses.
- 25. The motor speed control according to claim 23, wherein the microprocessor extends the interval between motor drive pulses during which back-e.m.f. is sampled to provide full recovery of the back-e.m.f. and sufficient sampling time.
- 26. A method for controlling motor speed comprising:
a) proving pulse modulation control of motor voltage drive pulses applied to the motor; b) sampling motor back-e.m.f. during intervals between motor drive pulses; c) comparing the sampled back-e.m.f. indicative of actual motor speed to a signal indicative of desired motor speed for controlling the pulse modulation; and d) determining the intervals between modulated motor drive pulses during which motor back-e.m.f. is sampled.
- 27. The method according to claim 26, wherein motor back-e.m.f. is sampled at a rate lower than the pulse rate of the modulated motor drive pulses.
- 28. The method according to claim 26, wherein the interval between motor drive pulses during which back-e.m.f. is sampled is extended to provide full recovery of the back-e.m.f. and sufficient sampling time.
CROSS REFERENCE TO A RELATED APPLICATION
[0001] Applicant claims priority based on U.S. provisional patent application No. 60/384,688 filed May 31, 2002 and entitled “Speed and Fluid Flow Controller” which is incorporated herein by reference.
Provisional Applications (1)
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Number |
Date |
Country |
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60384688 |
May 2002 |
US |