Patent US3880474A successfully refreshed from Google Patents.
US3880474A
Expired / Lapsed
US
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Skid control system
Assignee: ZF Active Safety US Inc
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Filing: 1971-10-18
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Granted: 1975-04-29
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Expires: 1991-10-18
Abstract
Abstract A control system and force motor assembly for controling the skidding of a vehicle under braked conditions wherein the control system provides a signal wave form which controls the position of an armature or fluid pressure controlling device in one of three conditions; the first being ''''dump'''' mode of operation wherein the force motor is controlled to preclude braking pressure from being supplied to the wheels of the vehicle, the ''''hold'''' mode of operation wherein the braking force present at the time the system goes into the ''''hold'''' mode of operation is maintained, and the ''''return'''' mode of operation wherein braking pressure is returned to the vehicle wheels. The control system is effectively responsive to a critical slip signal, the signal being generated in response to a sensed difference between a hypothetical vehicle deceleration, as approximated by a decreasing ramp signal, and the vehicle wheel speed. This comparison is made on a differential basis to provide an output signal which is utilized in controlling an output gate. The gate is also responsive to the sensing of a positive wheel acceleration signal and a change in sign of the rate of change of wheel acceleration. The signal from the output gate is fed to a second logic circuit which controls the operation of a variable duty cycle pulse generator, the duty cycle of the pulse generator being modulated in accordance with the sensed condition at the wheel, the lower end of the duty cycle range creating the ''''dump'''' mode of operation, the intermediate range duty cycle creating the ''''hold'''' mode of operation and the high duty cycle range providing the ''''return'''' mode of operation. The force motor is fabricated with a three position armature which is adapted to be placed either in the return or deactuated position where no signal is provided from the control circuit of a minimum duty cycle signal, a skid signal or dump mode of operation which connects the manually actuated brake cylinder hydraulically to the wheel cylinders to provide full braking pressure, and the hold position which maintains the pressure being fed to the wheels at the time the hold position is achieved. This latter position is actually a range of positions for the armature, the position being selected as a function of the position of the armature when the hold mode is entered.
Inventors
- 👤 Ronald S Scharlack
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:17
CPC Classifications
B; B60; B60T; B60T8/00; B60T8/17; B60T8/176; B60T8/1761; B60T8/17613; B60T8/32; B60T8/34; B60T8/36
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
210 words
A skid control system for controlling the operation of a control valve assembly connected in controlling relation with the hydraulic brake system of a wheeled vehicle, the valve assembly controlling the application of hydraulic force to the wheel brake to provide a run-down and spin-up portion of a brake cycle including a release, a reapply and a hold interval, the improvement comprising the control system having at least three modes of operation within a brake cycle and including an output coil, said system including pulse generating means including means for generating a stream of pulses in said intervals, said generating means generating a first pulsing signal formed of a first series of pulses within at least a portion of said release interval of the cycle, a second pulsing signal formed of a second series of pulses within at least a portion of the reapply interval for returning pressure from the wheel, and a third pulsing signal formed of a third series of pulses within at least a portion of the hold interval of the cycle, for holding pressure at the wheel during at least a portion of the acceleration portion of the wheel cycle, at least two of said signals varying in part, one from the other, in duty cycle.
Claim 2
Dependent Claim
210 words
A skid control system for controlling the operation of a control valve assembly connected in controlling relation with the hydraulic brake system of a wheeled vehicle, the valve assembly controlling the application of hydraulic force to the wheel brake to provide a run-down and spin-up portion of a brake cycle including a release, a reapply and a hold interval, the improvement comprising the control system having at least three modes of operation within a brake cycle and including an output coil, said system including pulse generating means including means for generating a stream of pulses in said intervals, said generating means generating a first pulsing signal formed of a first series of pulses within at least a portion of said release interval of the cycle, a second pulsing signal formed of a second series of pulses within at least a portion of the reapply interval for returning pressure from the wheel, and a third pulsing signal formed of a third series of pulses within at least a portion of the hold interval of the cycle, for holding pressure at the wheel during at least a portion of the acceleration portion of the wheel cycle, at least two of said signals varying in part, one from the other, in duty cycle.
Claim 3
Dependent Claim
30 words
The improvement of claim 1 wherein said control system includes means for sensing a critical slip signal, the sensing of said critical slip signal initiating the dump mode of operation.
Claim 4
Dependent Claim
44 words
The improvement of claim 2 wherein said control system includes means for sensing the wheel velocity, means for deriving the first and second derivatives of said wheel velocity and means for correlating said first and second derivative to initiate the hold mode of operation.
Claim 5
Dependent Claim
33 words
The improvement of claim 2 wherein said critical slip sensing means includes means for deriving a hypothetical vehicle velocity signal and means for comparing said vehicle velocity signal with said wheel velocity signal.
Claim 6
Dependent Claim
26 words
The improvement of claim 4 wherein said critical slip signal occurs when said wheel velocity signal drops a preselected amount below said hypothetical vehicle velocity signal.
Claim 7
Dependent Claim
44 words
The improvement of claim 1 wherein said control system includes means for sensing the wheel velocity, means for deriving the first and second derivatives of said wheel velocity and means for correlating said fiRst and second derivative to initiate the hold mode of operation.
Claim 8
Dependent Claim
29 words
The improvement of claim 6 wherein said control system includes means for sensing a change in sign in said second derivative signal for initiating said return mode of operation.
Claim 9
Dependent Claim
50 words
The improvement of claim 1 wherein said control system includes means for sensing the angular velocity of said wheel means for deriving the second derivative of said wheel velocity signal and means for sensing a change of sign of said second derivative signal for initiating said return mode of operation.
Claim 10
Dependent Claim
30 words
The improvement of claim 8 wherein said control system includes means for sensing a critical slip signal, the sensing of said critical slip signal initiating the dump mode of operation.
Claim 11
Dependent Claim
37 words
The improvement of claim 1 wherein said third pulsing signal is a signal having a relatively constant duty cycle to trap the hydraulic pressure force at the wheels upon sensing the acceleration portion of the wheel cycle.
Claim 12
Dependent Claim
115 words
The improvement of claim 1 wherein said control system includes wheel velocity sensing means, first means for generating a critical slip signal during the run-down portion of the wheel, second means for deriving the first derivative of said wheel velocity signal and third means for deriving the second derivative of said wheel velocity signal, said control circuit including logic means for correlating said first, second and critical slip signals to generate said first, second and third output signals, said first output signal having a characteristic of a generally increasing duty cycle, said second signal having a characteristic of a generally decreasing duty cycle and said third signal having a characteristic of a constant duty cycle.
Claim 13
Dependent Claim
264 words
A skid control system for controlling the operation of a control valve assembly connected in controlling relation with the hydraulic brake system of a wheeled vehicle, the valve assembly controlling the application of hydraulic force to the wheel brake, the improvement comprising the control system having at least three modes of operation and including a low inertia, output coil, said system generating a first pulsing signal at said coil for dumping the pressure from the wheel, a second pulsing signal for returning pressure from the wheel and a third pulsing signal for holding pressure at the wheel during at least a portion of the acceleration portion of the wheel cycle, at least two of said signals varying in part, one from the other, in duty cycle, wheel velocity sensing means, first means for generating a critical slip signal during the run-down portion of the wheel, second means for deriving the first derivative of said wheel velocity signal and third means for deriving the second derivative of said wheel velocity signal, said control circuit including logic means for correlating said first, second and critical slip signals to generate said first, second and third output signals, said first output signal having a characteristic of a generally increasing duty cycle, said second signal having a characteristic of a generally decreasing duty cycle and said third signal having a characteristic of a constant duty cycle, first logic gate means for correlating said first and second derivative signal and second logic gate means for correlating the output of said first logic gate means and said first critical slip signal.
Claim 14
Dependent Claim
264 words
A skid control system for controlling the operation of a control valve assembly connected in controlling relation with the hydraulic brake system of a wheeled vehicle, the valve assembly controlling the application of hydraulic force to the wheel brake, the improvement comprising the control system having at least three modes of operation and including a low inertia, output coil, said system generating a first pulsing signal at said coil for dumping the pressure from the wheel, a second pulsing signal for returning pressure from the wheel and a third pulsing signal for holding pressure at the wheel during at least a portion of the acceleration portion of the wheel cycle, at least two of said signals varying in part, one from the other, in duty cycle, wheel velocity sensing means, first means for generating a critical slip signal during the run-down portion of the wheel, second means for deriving the first derivative of said wheel velocity signal and third means for deriving the second derivative of said wheel velocity signal, said control circuit including logic means for correlating said first, second and critical slip signals to generate said first, second and third output signals, said first output signal having a characteristic of a generally increasing duty cycle, said second signal having a characteristic of a generally decreasing duty cycle and said third signal having a characteristic of a constant duty cycle, first logic gate means for correlating said first and second derivative signal and second logic gate means for correlating the output of said first logic gate means and said first critical slip signal.
Claim 15
Dependent Claim
25 words
The improvement of claim 12 including third logic gate means for correlating the output of said first logic gate means and said first derivative signal.
Claim 16
Dependent Claim
47 words
The improvement of claim 12 including variable duty cycle pulse generating circuit, said circuit generating said first, second and third pulse signals and an initial pulsing signal, said initial pulsing signal having a constant duty cycle and occuring at the start of the preskid mode of operation.
Claim 17
Dependent Claim
32 words
The improvement of claim 14 wherein said pulse generating circuit includes charge storage means, said charge storage means being initially charged to turn off the output pulses when said wheEl is unbraked.
Claim 18
Dependent Claim
21 words
The improvement of claim 15 wherein the effective charge of said charge storage means is reduced to produce said initial pulses.
Claim 19
Dependent Claim
26 words
The improvement of claim 16 wherein said charge is decreased along a generally linear curve to increase the output duty cycle of said first pulsing signal.
Claim 20
Dependent Claim
21 words
The improvement of claim 17 wherein said charge is maintained at a preselected level during said holding pressure mode of operation.
Claim 21
Dependent Claim
24 words
The improvement of claim 18 wherein said charge is increased along a linear curve to decrease the duty cycle of said second pulsing signal.
Claim 22
Dependent Claim
119 words
A skid control system for controlling the operation of a control valve assembly connected in controlling relationship with the hydraulic brake system of a wheeled vehicle, the first assembly controlling the application of hydraulic force to the wheel brake, the improvement comprising the method of operating the control system in at least three modes of operation including the steps of generating a first pulsing signal of a first increasing duty cycle characteristic for dumping pressure from the wheel, generating a second pulsing signal of decreasing duty cycle characteristic for returning the brake pressure to the wheel, and a third pulsing signal of a second constant duty cycle for holding the pressure during the acceleration portion of the wheel cycle.
Claim 23
Dependent Claim
119 words
A skid control system for controlling the operation of a control valve assembly connected in controlling relationship with the hydraulic brake system of a wheeled vehicle, the first assembly controlling the application of hydraulic force to the wheel brake, the improvement comprising the method of operating the control system in at least three modes of operation including the steps of generating a first pulsing signal of a first increasing duty cycle characteristic for dumping pressure from the wheel, generating a second pulsing signal of decreasing duty cycle characteristic for returning the brake pressure to the wheel, and a third pulsing signal of a second constant duty cycle for holding the pressure during the acceleration portion of the wheel cycle.
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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) | 1978-04-28 | 1978-10-28 | 1979-04-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-28 | 1982-10-28 | 1983-04-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-28 | 1986-10-28 | 1987-04-29 | $7700.00 | Window Closed / Lapsed |