US3577054A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reversible fail-safe wheelchair drive control circuit
Assignee: Everest and Jennings Inc
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Filing: 1969-01-24
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Granted: 1971-05-04
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Expires: 1989-01-24
Abstract
Abstract A drive control circuit for a motorized wheelchair whereby the wheelchair occupant can select both the direction and the rate of motion of the chair by means of a joystick. In both directions the same motor control circuit is used. To prevent a runaway motor condition which might be caused by a component breakdown in the drive control circuit, means are provided to deenergize the wheelchair motor rapidly.
Inventors
- 👤 Roger W Banks
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 21:05
CPC Classifications
H; H02; H02P; H02P7/00; H02P7/06; H02P7/18; H02P7/24; H02P7/28; H02P7/285; H02P7/29
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
254 words
A control system for motorized wheelchair comprising in combination: an electric motor operatively connected to drive said wheelchair when said motor is energized; an actuator having a limited range of travel and a rest position; variable resistance means including a resistance element and a contact coupled to said actuator selectively movable both (i) out of electrical engagement with said element in the rest position of said actuator and (ii) into electrical engagement with said element when said actuator is displaced from said rest position; semiconductor current control means electrically connected between said motor and a source of current for varying the amount of current applied to said electric motor, said semiconductor current control means responsively coupled to said variable resistance means so that selective movement of said contact correspondingly varies the amount of current supplied to said electric motor when said contact is in electrical engagement with said resistance element, said semiconductor current control means having the adverse characteristic that failure thereof can result in maximum energization of said motor independent of said actuator; and on-off switching means connected in series with said motor and said semiconductor current control means, said on-off switching means coupled to and responsive to current flowing through said resistance element of said variable resistance means when said contact and said resistance element are in electrical engagement so that the electric motor is positively deenergized when said contact is out of electrical engagement with said resistance element, said positive deenergization being provided regardless of failure of said current control means.
Claim 2
Dependent Claim
254 words
A control system for motorized wheelchair comprising in combination: an electric motor operatively connected to drive said wheelchair when said motor is energized; an actuator having a limited range of travel and a rest position; variable resistance means including a resistance element and a contact coupled to said actuator selectively movable both (i) out of electrical engagement with said element in the rest position of said actuator and (ii) into electrical engagement with said element when said actuator is displaced from said rest position; semiconductor current control means electrically connected between said motor and a source of current for varying the amount of current applied to said electric motor, said semiconductor current control means responsively coupled to said variable resistance means so that selective movement of said contact correspondingly varies the amount of current supplied to said electric motor when said contact is in electrical engagement with said resistance element, said semiconductor current control means having the adverse characteristic that failure thereof can result in maximum energization of said motor independent of said actuator; and on-off switching means connected in series with said motor and said semiconductor current control means, said on-off switching means coupled to and responsive to current flowing through said resistance element of said variable resistance means when said contact and said resistance element are in electrical engagement so that the electric motor is positively deenergized when said contact is out of electrical engagement with said resistance element, said positive deenergization being provided regardless of failure of said current control means.
Claim 3
Dependent Claim
54 words
The control system of claim 1 wherein: said on-off switching means includes a relay; said means for operatively connecting said actuator to said switching means opens the circuit of said relay only when said actuator is at said rest position; and said actuator automatically returns to said rest position when not manually deflected therefrom.
Claim 4
Dependent Claim
111 words
The control system of claim 1 wherein: said current control means is a transistor current amplifier; said means for selectively applying the output of said current control means is a double-pole double relay connected to reverse the direction of current flow through said motor; said means for operatively connecting said actuator to said means for selectively applying the output of said current control means includes switching means responsive to the shifting of said actuator through its rest position for applying electric current to said double-pole double-throw relay so as to reverse the position of its movable contacts; and said actuator automatically returns to said rest position when not manually deflected therefrom.
Claim 5
Dependent Claim
57 words
The control means of claim 1 wherein: said means for actuating said on-off switching means is a semiconductor switch; said on-off switching means is a relay whose coil is electrically connected to said semiconductor switch; and said semiconductor current control means is a semiconductor amplifier whose output is electrically connected between said motor and said current source.
Claim 6
Dependent Claim
242 words
A control system for a motorized wheelchair comprising in combination: an electric motor operatively connected to drive said wheelchair when said motor is energized; an actuator having a limited range of travel in each of two directions from a rest position; variable resistance means including a first and second resistance element and a contact coupled to said actuator selectively movable both (i) out of electrical engagement with both of said resistance elements in the rest position of said actuator, and (ii) into electrical engagement with respective ones of said resistance elements when said actuator is displaced from said rest position in a forward or reverse position; current control means responsively coupled to said variable resistance means and electrically connected between saId motor and a source of current for varying the amount of current applied to said electric motor in proportion to the excursion of said actuator from said rest position; and reversing means coupled between said current source and said motor having a deenergized position wherein the motor is caused to rotate in a predetermined direction and an energized position wherein the motor is caused to operate in an opposite direction, said reversing means coupled to and responsive to current flowing through one of said resistance elements of said variable resistance means when said contact and said resistance element are in electrical engagement so that said reversing means is deenergized when said contact is out of electrical engagement with said resistance element.
Claim 7
Dependent Claim
242 words
A control system for a motorized wheelchair comprising in combination: an electric motor operatively connected to drive said wheelchair when said motor is energized; an actuator having a limited range of travel in each of two directions from a rest position; variable resistance means including a first and second resistance element and a contact coupled to said actuator selectively movable both (i) out of electrical engagement with both of said resistance elements in the rest position of said actuator, and (ii) into electrical engagement with respective ones of said resistance elements when said actuator is displaced from said rest position in a forward or reverse position; current control means responsively coupled to said variable resistance means and electrically connected between saId motor and a source of current for varying the amount of current applied to said electric motor in proportion to the excursion of said actuator from said rest position; and reversing means coupled between said current source and said motor having a deenergized position wherein the motor is caused to rotate in a predetermined direction and an energized position wherein the motor is caused to operate in an opposite direction, said reversing means coupled to and responsive to current flowing through one of said resistance elements of said variable resistance means when said contact and said resistance element are in electrical engagement so that said reversing means is deenergized when said contact is out of electrical engagement with said resistance element.
Claim 8
Dependent Claim
59 words
The control system of claim 5 wherein: said second means has an energized state in which the motor operates in one direction and a deenergized state in which the motor operates in the opposite direction, and said fourth means energizes said second means only when said actuator is displaced in one of said two directions from said rest position.
Claim 9
Dependent Claim
54 words
The control system of claim 6 wherein: said second means is a double-pole double-throw relay connected to reverse the direction of current flow through said motor; and said fourth means includes means for energizing said double-pole double-throw relay only when said actuator is displaced in one of said two directions from said rest position.
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) | 1974-05-03 | 1974-11-02 | 1975-05-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-03 | 1978-11-02 | 1979-05-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-03 | 1982-11-02 | 1983-05-04 | $7700.00 | Window Closed / Lapsed |