US3841238A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Vehicle traction systems
Assignee: ZF International UK Ltd
•
Filing: 1972-01-26
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Granted: 1974-10-15
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Expires: 1992-01-26
Abstract
Abstract A vehicle traction system has a drive motor with the shunt field winding and a control circuit for the drive motor. A control circuit effects direct variation in the armature current with the current in the field winding fixed until it becomes impossible to increase the armature current directly. Control is then effected by varying the field winding current.
Inventors
- 👤 M Thompson
- 👤 B Phillips
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 01:42
CPC Classifications
H; H02; H02P; H02P7/00; H02P7/06; H02P7/18; H02P7/24; H02P7/28; H02P7/285; H02P7/29; H02P7/2913; H02P7/298; H02P7/2985; Y; Y10; Y10S; Y10S388/00; Y10S388/907; Y10S388/917
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
106 words
A vehicle traction system for a vehicle having an accelerator pedal comprising an electric drive motor for the vehicle, a control system for the drive motor, said control system comprising a function generator for effecting direct variation of the motor armature current, the function generator receiving input signals representing the position of the accelerator pedal and the engine speed, said function generator comprising means dependent on said input signals for establishing a preselected output current range of minimum and maximum allowable armature currents and for maintaining said range the same as the position of the accelerator pedal is changed to vary the speed of the vehicle.
Claim 2
Dependent Claim
106 words
A vehicle traction system for a vehicle having an accelerator pedal comprising an electric drive motor for the vehicle, a control system for the drive motor, said control system comprising a function generator for effecting direct variation of the motor armature current, the function generator receiving input signals representing the position of the accelerator pedal and the engine speed, said function generator comprising means dependent on said input signals for establishing a preselected output current range of minimum and maximum allowable armature currents and for maintaining said range the same as the position of the accelerator pedal is changed to vary the speed of the vehicle.
Claim 3
Dependent Claim
76 words
A system as claimed in claim 1, wherein said electric drive motor has a shunt field winding and wherein a field current control circuit is provided for maintaining current flow in said field winding, said system further including field control means operable automatically when back EMF developed in the armature prevents the increase of armature current to the level set by said function generator for over-riding said field current control circuit and lowering the field current.
Claim 4
Dependent Claim
58 words
A system as claimed in claim 2 in which the armature current control circuit comprises a thyristor power controller having a thyristor connected in series with the armature and commutating means for turning said thyristor off, and a firing circuit controlled by the function generator and supplying signals to the controller to turn the thyristor on and off.
Claim 5
Dependent Claim
29 words
A system as claimed in claim 3 in which the function generator sets upper and lower armature current levels at which the thyristor is turned off and on respectively.
Claim 6
Dependent Claim
31 words
A system as claimed in claim 4 including means for ensuring that the thyristor is on for a minimum period of time sufficient to ensure satisfactory operation of the power controller.
Claim 7
Dependent Claim
31 words
A system as claimed in claim 4 including means for ensuring that the thyristor is off for a minimum period of time sufficient to ensure satisfactory operation of the power controller.
Claim 8
Dependent Claim
29 words
A system as claimed in claim 4 including means for turning said thyristor off after a predetermined period of time if said upper current level has not been attained.
Claim 9
Dependent Claim
18 words
A system as claimed in claim 4 including means restricting the maximum switching frequency of the power controller.
Claim 10
Dependent Claim
38 words
A system as claimed in claim 4 including means operable when the system is switched on for ensuring that before the thyristor is turned on, the commutating means is in a condition to turn the thyristor off again.
Claim 11
Dependent Claim
58 words
A system as claimed in claim 2 including a comparator coupled to the function generator and armature so as to receive signals representing the desired armature current and the actual armature current, said comparator forming part of the field control means and serving when the desired armature current exceeds the actual armature current to lower the field current.
Claim 12
Dependent Claim
66 words
A system as claimed in claim 10 in which the field current control circuit includes in addition to the first mentioned comparator a second comparator which compares the actual field current with a desired field current and acts to maintain the field current at the desired level, the output from the first mentioned comparator being coupled to the second comparator to vary the desired field current.
Claim 13
Dependent Claim
25 words
A system as claimed in claim 11 in which the desired field current is, in the absence of any signal from the first comparator, constant.
Claim 14
Dependent Claim
29 words
A system as claimed in claim 11 in which the desired field current is, in the absence of any signal from the first comparator, varied in a predetermined manner.
Claim 15
Dependent Claim
38 words
A system as claimed in claim 13 in which the desired field current is, in the absence of any signal from the first comparator, constant except for light throttle pedal settings, when the desired field current is reduced.
Claim 16
Dependent Claim
71 words
A system as claimed in claim 2 in which said function generator serves, assuming the accelerator pedal to be completely depressed, to maintain constant armature current until a first vehicle speed is reached, and then decrease the armature current until a second vehicle speed is reached, then to maintain the armature current at the lower value until a third vehicle speed is reached, and finally, to decrease the armature current again.
Claim 17
Dependent Claim
17 words
A system as claimed in claim 2 in which the motor also incorporates a series field winding.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-14 | 1978-04-15 | 1978-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-14 | 1982-04-15 | 1982-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-14 | 1986-04-15 | 1986-10-15 | $7700.00 | Window Closed / Lapsed |