US4941553A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Vehicle braking system
Assignee: ZF International UK Ltd
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Filing: 1988-11-18
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Granted: 1990-07-17
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Expires: 2008-11-18
Abstract
Abstract A braking system for a vehicle has a stepper motor which controls the application of friction elements to a rotating part such as a brake drum. A control circuit controls the motor so that an output member is positioned by the motor in accordance with a variable demand signal. In one application, the control circuit receives a brake pressure signal from a transducer and controls the motor so as to compensate automatically for brake wear. In another application, the motor controls a debooster of an antilock brake system. The system also may include means for operating a parking brake.
Inventors
- 👤 Anthony W. Harrison
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 07:32
CPC Classifications
F; F16; F16D; F16D65/00; F16D65/14; F16D65/28; B; B60; B60T; B60T8/00; B60T8/32; B60T8/34; B60T8/42; B60T8/4208; B60T8/4266; F16D66/00; F16D2066/003; F16D2066/005; F16D2121/00; F16D2121/18; F16D2121/24; F16D2125/00; F16D2125/02; F16D2125/10; F16D2125/18; F16D2125/20; F16D2125/34; F16D2125/40; F16D2127/00; F16D2127/007; F16D2127/06
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
107 words
A braking system comprising a rotating part, a friction element for cooperating with said rotating part to provide braking, a motor having an output member for controlling said friction element, and a control circuit for receiving a variable demand signal, said motor comprising a stator and a rotor which is arranged to be brought to rest at any one of a plurality of distinct positions, said control circuit controlling said motor so as to drive said output member to a position in accordance with the variable demand signal and to provide automatic adjustment of a datum position of said friction element to compensate automatically for wear thereof.
Claim 2
Dependent Claim
107 words
A braking system comprising a rotating part, a friction element for cooperating with said rotating part to provide braking, a motor having an output member for controlling said friction element, and a control circuit for receiving a variable demand signal, said motor comprising a stator and a rotor which is arranged to be brought to rest at any one of a plurality of distinct positions, said control circuit controlling said motor so as to drive said output member to a position in accordance with the variable demand signal and to provide automatic adjustment of a datum position of said friction element to compensate automatically for wear thereof.
Claim 3
Dependent Claim
56 words
A braking system as claimed in claim 1, in which said control circuit includes a drive circuit having an input, said drive circuit driving said motor to cause said rotor to be turned to a next one of the plurality of distinct positions in response to each pulse received at said input of said drive circuit.
Claim 4
Dependent Claim
46 words
A braking system as claimed in claim 2, in which said motor is a switched reluctance stepper motor having a plurality of windings and said drive circuit is arranged to switch current in each of said plurality of windings in a plurality of predetermined different combinations.
Claim 5
Dependent Claim
69 words
A braking system as claimed in claim 1, further comprising auxiliary magnetic circuit means including permanent magnet means, a first part fixed with respect to said stator, and a second part fixed with respect to said rotor, said first and second parts being shaped and disposed such that there is a plurality of relative positions thereof at which the reluctance of said auxiliary magnetic circuit means is a minimum.
Claim 6
Dependent Claim
70 words
A braking system as claimed in claim 4, in which said motor has n distinct positions and said first and second parts comprise first and second toothed rings at least one of which has x, n teeth, where x is a positive non-zero integer, said first and second rings being arranged such that said teeth thereof are aligned whenever said rotor is in any one of the n distinct positions.
Claim 7
Dependent Claim
28 words
A braking system as claimed in claim 5, in which at least one of said first and second rings is permanently magnetised to provide said permanent magnet means.
Claim 8
Dependent Claim
28 words
A braking system as claimed in claim 6, in which said teeth of said at least one of said first and second rings alternate circumferentially in magnetic polarity.
Claim 9
Dependent Claim
38 words
A braking system as claimed in claim 6, in which said teeth of said at least one of said first and second rings form a plurality of groups of adjacent teeth, said groups alternating circumferentially in magnetic polarity.
Claim 10
Dependent Claim
50 words
A braking system as claimed in claim 5, in which each of at least one of said first and second rings comprises a plurality of toothed soft iron rings, each adjacent pair of said rings being axially separated by an annular axially polarised permanent magnet providing said permanent magnet means.
Claim 11
Dependent Claim
23 words
A braking system as claimed in claim 5, in which said permanent magnet means comprises at least one annular radially polarised permanent magnet.
Claim 12
Dependent Claim
42 words
A braking system as claimed in claim 1, further comprising a transducer arranged to measure brake load, said control circuit holding a position count and resetting the position count when the brake load measured by said transducer is within a threshold range.
Claim 13
Dependent Claim
33 words
A braking system as claimed in claim 11, further comprising a hydraulic actuator for actuating said friction element, said transducer comprising an hydraulic pressure transducer for measuring hydraulic pressure in said hydraulic actuator.
References Cited (Backward Citations)
US2548731A
Cited
US3790225A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-07-16 | 1994-01-15 | 1994-07-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-07-16 | 1998-01-15 | 1998-07-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-07-16 | 2002-01-15 | 2002-07-17 | $7700.00 | Window Closed / Lapsed |