US3801887A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Brushless variable speed drive for a. c. synchronous motor
Assignee: AMF Inc
•
Filing: 1973-04-10
•
Granted: 1974-04-02
•
Expires: 1993-04-10
Abstract
Abstract A motor speed control circuit is provided for varying the speed of a motor in response to a change in an ambient parameter. An A.C. hysteresis motor is driven from a D. C. supply by a multivibrator. The multivibrator is driven in synchronism with a unijunction relaxation oscillator which oscillates at a variable frequency determined by changes in said ambient parameter. A resistive sensor means is provided in circuit with the relaxation oscillator for detecting changes in the ambient parameter. The resistance of the sensor varies logarithmically with changes in the ambient parameter. The unijunction oscillator means is provided with means to compensate for the logarithmic change in the sensor, to thereby provide an oscillator frequency which varies linearly with said ambient parameter. Since the speed of the motor is controlled by the frequency of the oscillator, the motor speed is also a linear function of the change in the ambient parameter.
Inventors
- 👤 J Allard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 19:39
CPC Classifications
H; H02; H02P; H02P25/00; H02P25/02; H02P25/022; H02P25/024
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
118 words
A transducer for driving a variable speed motor at speeds which vary as a linear function of an ambient parameter comprising: a. means for sensing said ambient parameter and generating a signal which varies logarithmically with said ambient parameter; b. oscillator means coupled to said sensing means and to circuit means for generating a signal which varies exponentially with respect to time; c. means for controlling the frequency of said oscillator means as a combined function of said logarithmic and exponential signals to thereby vary said frequency linearly with said ambient parameter; and d. synchronous motor means coupled to said oscillator means, said synchronous motor being driven at a speed determined by the frequency of said oscillator means.
Claim 2
Dependent Claim
118 words
A transducer for driving a variable speed motor at speeds which vary as a linear function of an ambient parameter comprising: a. means for sensing said ambient parameter and generating a signal which varies logarithmically with said ambient parameter; b. oscillator means coupled to said sensing means and to circuit means for generating a signal which varies exponentially with respect to time; c. means for controlling the frequency of said oscillator means as a combined function of said logarithmic and exponential signals to thereby vary said frequency linearly with said ambient parameter; and d. synchronous motor means coupled to said oscillator means, said synchronous motor being driven at a speed determined by the frequency of said oscillator means.
Claim 3
Dependent Claim
13 words
The transducer of claim 1 wherein said ambient parameter sensed is relative humidity.
Claim 4
Dependent Claim
41 words
The transducer of claim 1 wherein there is further provided bistable multivibrator means for driving said synchronous motor, said bistable multivibrator being coupled to said oscillator means to drive said synchronous motor in synchronism with the frequency of said oscillator means.
Claim 5
Dependent Claim
25 words
The transducer of claim 1 wherein there is further provided semiconductor switch means for gating the output of said oscillator means to said bistable multivibrator.
Claim 6
Dependent Claim
178 words
A transducer for driving a variable speed motor at speeds which vary as a function of an ambient parameter comprising: a. synchronous motor means; b. bistable multivibrator means for driving said synchronous motor means; c. oscillator means for driving said bistable multivibrator means in synchronism with the frequency of said oscillator means, said oscillator means including semiconductor means having a gate electrode, an anode, and a cathode, said semi-conductor means being rendered conductive to generate a pulse through said cathode to said multivibrator means at a frequency determined by the relative voltage at said gate electrode and said anode; d. means for supplying a voltage to said anode which varies exponentially with time; and e. means coupled to the gate electrode of said oscillator for sensing said ambient parameter and generating a voltage at said gate which varies as a function of said ambient parameter; whereby the combined functions of the voltages applied to said gate and anode of said oscillator means constrain the frequency of said oscillator means to vary as a function of said ambient parameter.
Claim 7
Dependent Claim
178 words
A transducer for driving a variable speed motor at speeds which vary as a function of an ambient parameter comprising: a. synchronous motor means; b. bistable multivibrator means for driving said synchronous motor means; c. oscillator means for driving said bistable multivibrator means in synchronism with the frequency of said oscillator means, said oscillator means including semiconductor means having a gate electrode, an anode, and a cathode, said semi-conductor means being rendered conductive to generate a pulse through said cathode to said multivibrator means at a frequency determined by the relative voltage at said gate electrode and said anode; d. means for supplying a voltage to said anode which varies exponentially with time; and e. means coupled to the gate electrode of said oscillator for sensing said ambient parameter and generating a voltage at said gate which varies as a function of said ambient parameter; whereby the combined functions of the voltages applied to said gate and anode of said oscillator means constrain the frequency of said oscillator means to vary as a function of said ambient parameter.
Claim 8
Dependent Claim
14 words
The transducer of claim 5 wherein said semiconductor means is a programmable unijunction transistor.
Claim 9
Dependent Claim
20 words
The transducer of claim 5 wherein semiconductor gate means are provided for coupling said oscillator means to said bistable multivibrator.
Claim 10
Dependent Claim
26 words
The transducer of claim 5 wherein said means for sensing said ambient parameter comprises resistive means, the resistance of whiCh varies logarithmically with the ambient parameter.
Claim 11
Dependent Claim
47 words
The transducer of claim 8 wherein said resistive means is biased with A. C. power and said oscillator means is biased with D. C. power and means are provided for isolating the A. C. power of said resistive means and the D.C. power of said oscillator means.
Claim 12
Dependent Claim
13 words
The transducer of claim 5 wherein said ambient paramter sensed is relative humidity.
Claim 13
Dependent Claim
89 words
A transducer for varying the frequency of an oscillator as a linear function of an ambient parameter comprising: a. means for sensing said ambient parameter and generating a signal which varies logarithmically with said ambient parameter; b. oscillator means coupled to said sensing means and to circuit means for generating a signal which varies exponentially with respect to time; c. means for controlling the frequency of said oscillator means as a combined function of said logarithmic and exponential signals to thereby vary said frequency linearly with said ambient parameter.
Claim 14
Dependent Claim
89 words
A transducer for varying the frequency of an oscillator as a linear function of an ambient parameter comprising: a. means for sensing said ambient parameter and generating a signal which varies logarithmically with said ambient parameter; b. oscillator means coupled to said sensing means and to circuit means for generating a signal which varies exponentially with respect to time; c. means for controlling the frequency of said oscillator means as a combined function of said logarithmic and exponential signals to thereby vary said frequency linearly with said ambient parameter.
Claim 15
Dependent Claim
13 words
The transducer of claim 11 wherein said ambient parameter sensed is relative humidity.
Claim 16
Dependent Claim
41 words
The transducer of claim 11 wherein there is further provided bistable multivibrator means for driving a synchronous motor, said bistable multivibrator being coupled to said oscillator means to drive said synchronous motor in synchronism with the frequency of said oscillator means.
Claim 17
Dependent Claim
25 words
The transducer of claim 11 wherein there is further provided semiconductor switch means for gating the output of said oscillator means to said bistable multivibrator.
Claim 18
Dependent Claim
139 words
A transducer for varying the frequency of an oscillator as a function of an ambient parameter comprising: a. oscillator means including a semiconductor means having a gate electrode, an anode, and a cathode, said semiconductor means being rendered conductive to generate output pulses at said cathode at a frequency determined by the relative voltages at said gate electrode and said anode; b. means for supplying a voltage to said anode which varies exponentially with time; and c. means coupled to the gate electrode of said oscillator for sensing said ambient parameter and generating a voltage at said gate which varies as a function of said ambient parameter; whereby the combined functions of the voltages applied to said gate and anode of said oscillator means constrain the frequency of said oscillator means to vary as a function said ambient parameter.
Claim 19
Dependent Claim
139 words
A transducer for varying the frequency of an oscillator as a function of an ambient parameter comprising: a. oscillator means including a semiconductor means having a gate electrode, an anode, and a cathode, said semiconductor means being rendered conductive to generate output pulses at said cathode at a frequency determined by the relative voltages at said gate electrode and said anode; b. means for supplying a voltage to said anode which varies exponentially with time; and c. means coupled to the gate electrode of said oscillator for sensing said ambient parameter and generating a voltage at said gate which varies as a function of said ambient parameter; whereby the combined functions of the voltages applied to said gate and anode of said oscillator means constrain the frequency of said oscillator means to vary as a function said ambient parameter.
Claim 20
Dependent Claim
14 words
The transducer of claim 15 wherein said semiconductor means is a programable unijunction transistor.
Claim 21
Dependent Claim
20 words
The transducer of claim 15 wherein semiconductor gate means are provided for coupling said oscillator means to said bistable multivibrator.
Claim 22
Dependent Claim
26 words
The transducer of claim 15 wherein said means for sensing said ambient parameter comprises resistive means, the resistance of which varies logarithmically with the ambient parameter.
Claim 23
Dependent Claim
49 words
The transducer of claim 18 wherein said resistive means is biased with the A. C. power and said oscillator means is biased with D. C. power and means are provided for isolating the A. C. power of said resistive means and the D. C. power of said oscillator means.
Claim 24
Dependent Claim
13 words
The transducer of claim 15 wherein said ambient parameter sensed is relative humidity.
Claim 25
Dependent Claim
34 words
The transducer of claim 5 wherein the voltage at the gate of said semiconductor means varies exponentially with said ambient parameter and the frequency of said oscillator means varies linearly with said ambient parameter.
Claim 26
Dependent Claim
34 words
The transducer of claim 15 wherein the voltage at the gate of said semiconductor means varies exponentially with said ambient parameter and the frequency of said oscillator means varies linearly with said ambient parameter.
Claim 27
Dependent Claim
153 words
A tranducer for driving a motor at speeds which vary as a linear function of an ambient parameter comprising: a. means for sensing said ambient parameter and generating a first signal which varies as a first nonlinear function with changes in said ambient parameter; b. oscillAtor means for producing an oscillating signal; c. circuit means coupled to said oscillator for producing a second signal which varies as a second and different nonlinear function with respect to time; d. means coupling said sensing means to said oscillator means for changing said second signal to a third nonlinear signal; e. said second and third signals controlling said oscillator to vary the oscillator frequency as a linear function of change in said ambient parameter; f. a synchronous motor; and g. means for coupling said oscillator signal to said motor for controlling the speed of said motor as a linear function of change in said ambient parameter.
Claim 28
Dependent Claim
153 words
A tranducer for driving a motor at speeds which vary as a linear function of an ambient parameter comprising: a. means for sensing said ambient parameter and generating a first signal which varies as a first nonlinear function with changes in said ambient parameter; b. oscillAtor means for producing an oscillating signal; c. circuit means coupled to said oscillator for producing a second signal which varies as a second and different nonlinear function with respect to time; d. means coupling said sensing means to said oscillator means for changing said second signal to a third nonlinear signal; e. said second and third signals controlling said oscillator to vary the oscillator frequency as a linear function of change in said ambient parameter; f. a synchronous motor; and g. means for coupling said oscillator signal to said motor for controlling the speed of said motor as a linear function of change in said ambient parameter.
References Cited (Backward Citations)
US2898533A
Cited
US2995690A
Cited
US3098958A
Cited
US3250066A
Cited
US3489968A
Cited
US3473069A
Cited
US3613391A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-04-01 | 1977-10-01 | 1978-04-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-01 | 1981-10-01 | 1982-04-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-01 | 1985-10-01 | 1986-04-02 | $7700.00 | Window Closed / Lapsed |