US3689818A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control means for electric motors operated from batteries
Assignee: Cableform Ltd
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Filing: 1971-02-16
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Granted: 1972-09-05
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Expires: 1991-02-16
Abstract
Abstract In, for example, battery operated vehicles such as fork lift trucks, the electric motor is supplied with pulses of current from a D.C. switch comprising thyristors. If spurious signals get into the control circuit the vehicle may take off out of control. The invention provides a control circuit in which the pulses of current through the D.C. switch are compared with the control signal pulses and in which the D.C. switch is disabled if there is a current signal in the absence of a control signal.
Inventors
- 👤 John Morton
- 👤 Keith Drummond Stevens
- 👤 Graham Spencer Thexton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 06:56
CPC Classifications
H; H02; H02P; H02P7/00; H02P7/06; H02P7/18; H02P7/24; H02P7/28; H02P7/285; H02P7/29; G; G07; G07F; G07F17/00; G07F17/30; G07F17/305; G07F5/00; G07F5/20; G07F5/22; H02H; H02H7/00; H02H7/08; H02H7/0833; H02H7/0844
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
89 words
A control means for a battery operated electric motor, comprising a D.C. switch arrangement for controlling the supply of current pulses from a battery to an electric motor, means for obtaining a current signal when current flows from the battery through the switch arrangement, means for comparing and determining concurrence of the current signal with the control pulse signal to the D.C. switch arrangement and means for disabling the D.C. switch arrangement if said comparing means determines there is a current signal in the absence of a control signal.
Claim 2
Dependent Claim
89 words
A control means for a battery operated electric motor, comprising a D.C. switch arrangement for controlling the supply of current pulses from a battery to an electric motor, means for obtaining a current signal when current flows from the battery through the switch arrangement, means for comparing and determining concurrence of the current signal with the control pulse signal to the D.C. switch arrangement and means for disabling the D.C. switch arrangement if said comparing means determines there is a current signal in the absence of a control signal.
Claim 3
Dependent Claim
110 words
A control means for a battery operated electric motor, comprising a D.C. switch arrangement for controlling the supply of current pulses from a battery to an electric motor, means for obtaining a current signal when current flows from the battery through the switch arrangement, means for comparing the current signal with the control pulse signal to the D.C. switch arrangement and means for disabling the D.C. switch arrangement if there is a current signal in the absence of a control signal, and wherein the motor has a reversible field switched by a forward/reverse contactor and said disabling is brought about by opening contacts in the energization circuit to the contactor.
Claim 4
Dependent Claim
110 words
A control means for a battery operated electric motor, comprising a D.C. switch arrangement for controlling the supply of current pulses from a battery to an electric motor, means for obtaining a current signal when current flows from the battery through the switch arrangement, means for comparing the current signal with the control pulse signal to the D.C. switch arrangement and means for disabling the D.C. switch arrangement if there is a current signal in the absence of a control signal, and wherein the motor has a reversible field switched by a forward/reverse contactor and said disabling is brought about by opening contacts in the energization circuit to the contactor.
Claim 5
Dependent Claim
26 words
Means as claimed in claim 2, wherein once the D.C. switch arrangement is disabled it remains disabled until a manual operation is performed to release it.
Claim 6
Dependent Claim
37 words
Means as claimed in claim 1, wherein the current signal is applied to the base of a first transistor which is inhibited by a second transistor during the existence of a control pulse signal at its base.
Claim 7
Dependent Claim
159 words
A control means for a battery operated electric motor, comprising a D.C. switch arrangement for controlling the supply of current pulses from a battery to an electric motor, means for obtaining a current signal when current flows from the battery through the switch arrangement, means for comparing the current signal with the control pulse signal to the D.C. switch arrangement and means for disabling the D.C. switch arrangement if there is a current signal in the absence of a control signal, wherein the current signal is applied to the base of a first transistor which is inhibited by a second transistor during the existence of a control pulse signal at its base, and wherein the collector of said first transistor is connected to the base of a third transistor whiCh is conductive while the first transistor is inhibited and which has a relay in its output circuit, contacts of the relay operating to disable the D.C. switch when open.
Claim 8
Dependent Claim
159 words
A control means for a battery operated electric motor, comprising a D.C. switch arrangement for controlling the supply of current pulses from a battery to an electric motor, means for obtaining a current signal when current flows from the battery through the switch arrangement, means for comparing the current signal with the control pulse signal to the D.C. switch arrangement and means for disabling the D.C. switch arrangement if there is a current signal in the absence of a control signal, wherein the current signal is applied to the base of a first transistor which is inhibited by a second transistor during the existence of a control pulse signal at its base, and wherein the collector of said first transistor is connected to the base of a third transistor whiCh is conductive while the first transistor is inhibited and which has a relay in its output circuit, contacts of the relay operating to disable the D.C. switch when open.
Claim 9
Dependent Claim
54 words
Means as claimed in claim 5, wherein the output of the third transistor is connected back to the base of the first transistor so that when conduction of the third transistor ceases due to conduction of the first transistor the first transistor is locked-on conductive and can be released only by a manual operation.
Claim 10
Dependent Claim
151 words
A control means for a battery operated electric motor, comprising a D.C. switch arrangement for controlling the supply of current pulses from a battery to an electric motor, means for obtaining a current signal when current flows from the battery through the switch arrangement, means for comparing the current signal with the control pulse signal to the D.C. switch arrangement and means for disabling the D.C. switch arrangement if there is a current signal in the absence of a control signal, wherein the current signal is applied to the base of a first transistor which is inhibited by a second transistor during the existence of a control pulse signal at its base, and wherein a capacitor is connected across the base input to the first transistor to provide a time delay sufficient to cover the time of charging of a cummutating capacitor associated with the thyristors in the D.C. switch arrangement.
Claim 11
Dependent Claim
151 words
A control means for a battery operated electric motor, comprising a D.C. switch arrangement for controlling the supply of current pulses from a battery to an electric motor, means for obtaining a current signal when current flows from the battery through the switch arrangement, means for comparing the current signal with the control pulse signal to the D.C. switch arrangement and means for disabling the D.C. switch arrangement if there is a current signal in the absence of a control signal, wherein the current signal is applied to the base of a first transistor which is inhibited by a second transistor during the existence of a control pulse signal at its base, and wherein a capacitor is connected across the base input to the first transistor to provide a time delay sufficient to cover the time of charging of a cummutating capacitor associated with the thyristors in the D.C. switch arrangement.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-09-05 | 1976-03-06 | 1976-09-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-09-05 | 1980-03-06 | 1980-09-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-09-05 | 1984-03-06 | 1984-09-05 | $7700.00 | Window Closed / Lapsed |