US3663070A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Skid control system
Assignee: ZF Active Safety US Inc
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Filing: 1969-11-10
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Granted: 1972-05-16
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Expires: 1989-11-10
Abstract
Abstract A control system and force motor assembly for controlling the skidding of a vehicle under braked conditions when the control system provides a signal for controlling the position of an armature or fluid pressure controlling device in one of three conditions; the first condition being the ''''dump'''' mode of operation when the force motor is controlled to preclude braking pressure from being supplied to the wheels of the vehicle, the ''''hold'''' mode of operation when the braking force presented at the time the system goes into the ''''hold'''' mode of operation is maintained, and the ''''return'''' mode of operation when full applied 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 an output logic circuit, the output logic circuit also being rendered responsive to the first derivative of the wheel velocity signal and a combination of first and second derivative of the wheel velocity signal. The output signals are utilized in the output logic circuit to generate one of three signal conditions across the solenoid coil of the force motor actuator assembly. In the return mode of operation, the polarity of the output signals generated across the solenoid coil are of the same polarity to cause zero current to flow through the solenoid coil. In the dump mode of operation, the coil is provided with current flow in a first direction and in the hold mode of operation the solenoid coil is supplied with current flowing in a second direction opposite to the first direction. The force motor is fabricated with a three positioned armature which is adapted to be placed either in the return or deactuated position, where no signals are provided from the control circuit; a 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.
Inventors
- 👤 Ronald S Scharlack
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 17:57
CPC Classifications
B; B60; B60T; B60T8/00; B60T8/17; B60T8/176; B60T8/1761; B60T8/17613; B60T8/32; B60T8/58; Y; Y10; Y10S; Y10S303/00; Y10S303/05
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
172 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 valve 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 sensing the wheel velocity, generating a critical slip signal in response to said sensed wheel velocity and initiating the dump mode of operation in response to said critical slip signal, deriving the first and second derivative of said wheel velocity, correlating said first and second derivatives of said wheel velocity, initiating the hold mode of operation in response to said correlated derivative signals, sensing a change in sign in said second derivative signal, and initiating said return mode of operation in response to said change in sign, said hold mode duration being determined substantially by said correlation of said first and second derivatives and said change in sign of said second derivative.
Claim 2
Dependent Claim
172 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 valve 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 sensing the wheel velocity, generating a critical slip signal in response to said sensed wheel velocity and initiating the dump mode of operation in response to said critical slip signal, deriving the first and second derivative of said wheel velocity, correlating said first and second derivatives of said wheel velocity, initiating the hold mode of operation in response to said correlated derivative signals, sensing a change in sign in said second derivative signal, and initiating said return mode of operation in response to said change in sign, said hold mode duration being determined substantially by said correlation of said first and second derivatives and said change in sign of said second derivative.
Claim 3
Dependent Claim
260 words
A skid control system for controlling the operation of a control valve assembly connected in controlling relation with the hydraulic system of a wheeled vehicle, the valve assembly controlling the application of hydraulic force to the wheel brake, the improvement comprising means for sensing a critical slip signal, means for sensing the wheel velocity, means connected to said wheel velocity sensing means for deriving the first and second derivatives of said wheel velocity, means connected to respond to said derivative deriving means for correlating said first and second derivatives, means for sensing a change in sign in said second derivative signal, said control system having at least three modes of operation and including an output coil, said system generating a first signal at said coil for dumping the pressure from the wheel in response to sensing said critical slip signal, means connected to said change in sign sensing means for generating a second signal for returning pressure to the wheel in response to said change in sign sensing means, and means for generating a third signal in response to said correlating means for holding pressure at the wheel during at least a portion of the acceleration portion of the wheel cycle, said correlating means initiating the hold mode of operation, and means connected to said second signal sensing means for initiating said return mode of operation in response to the sensed change of sign of said second derivative signal, said hold mode duration being determined substantially by said correlating means and said change in sign of said second derivative signal.
Claim 4
Dependent Claim
260 words
A skid control system for controlling the operation of a control valve assembly connected in controlling relation with the hydraulic system of a wheeled vehicle, the valve assembly controlling the application of hydraulic force to the wheel brake, the improvement comprising means for sensing a critical slip signal, means for sensing the wheel velocity, means connected to said wheel velocity sensing means for deriving the first and second derivatives of said wheel velocity, means connected to respond to said derivative deriving means for correlating said first and second derivatives, means for sensing a change in sign in said second derivative signal, said control system having at least three modes of operation and including an output coil, said system generating a first signal at said coil for dumping the pressure from the wheel in response to sensing said critical slip signal, means connected to said change in sign sensing means for generating a second signal for returning pressure to the wheel in response to said change in sign sensing means, and means for generating a third signal in response to said correlating means for holding pressure at the wheel during at least a portion of the acceleration portion of the wheel cycle, said correlating means initiating the hold mode of operation, and means connected to said second signal sensing means for initiating said return mode of operation in response to the sensed change of sign of said second derivative signal, said hold mode duration being determined substantially by said correlating means and said change in sign of said second derivative signal.
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 3 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
15 words
The improvement of claim 4 wherein said vehicle velocity signal is a linearly decreasing ramp.
Claim 8
Dependent Claim
240 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 an output coil, a critical slip signal generating means for generating a signal in response to a preselected slip, and a dIfferentiating circuit including a wheel speed sensor for generating a first signal which is the first derivative of the wheel speed and a second signal which is the second derivative of the wheel speed, said system generating a first signal at said coil for dumping the pressure from the wheel, a second signal for returning pressure from the wheel and a third signal for holding pressure at the wheel during at least a portion of the acceleration portion of the wheel cycle, said critical slip signal generating means operating to generate said critical slip signal during the run-down portion of the wheel, said control system further including logic means for correlating said first, second and critical slip signals to generate an output signal having a first polarity in response to sensing said critical slip signal, a second polarity output signal in response to a change in first derivative and a zero signal in response to sensing a change in sign of said second derivative signal.
Claim 9
Dependent Claim
240 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 an output coil, a critical slip signal generating means for generating a signal in response to a preselected slip, and a dIfferentiating circuit including a wheel speed sensor for generating a first signal which is the first derivative of the wheel speed and a second signal which is the second derivative of the wheel speed, said system generating a first signal at said coil for dumping the pressure from the wheel, a second signal for returning pressure from the wheel and a third signal for holding pressure at the wheel during at least a portion of the acceleration portion of the wheel cycle, said critical slip signal generating means operating to generate said critical slip signal during the run-down portion of the wheel, said control system further including logic means for correlating said first, second and critical slip signals to generate an output signal having a first polarity in response to sensing said critical slip signal, a second polarity output signal in response to a change in first derivative and a zero signal in response to sensing a change in sign of said second derivative signal.
Claim 10
Dependent Claim
25 words
The improvement of claim 6 including third logic gate means for correlating the output of said first logic gate means and said first derivative signal.
Claim 11
Dependent Claim
34 words
The improvement of claim 7 further including an output logic circuit, said output logic circuit including first and second output gates, said first and second output gates generating output signals across said output coil.
Claim 12
Dependent Claim
35 words
The improvement of claim 8 wherein said first output logic gate includes an input signal from said second and third logic gates, said first output gate being connected to one end of said output coil.
Claim 13
Dependent Claim
41 words
The improvement of claim 9 wherein said second output logic gate includes an input from said first output logic gate and said second logic gate means, said second output logic gate being connected to the opposite end of said output coil.
Claim 14
Dependent Claim
42 words
The improvement of claim 10 wherein, during said dump mode of operation, said first output gate provides an output signal of a first polarity and said second output gate provides an output signal of a second polarity opposite to said first polarity.
Claim 15
Dependent Claim
25 words
The improvement of claim 11 wherein the outputs of said first and second output gates are reversed in polarity for said hold mode of operation.
Claim 16
Dependent Claim
23 words
The improvement of claim 12 wherein the outputs of said first and second output gates are equal for said return mode of operation.
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) | 1975-05-16 | 1975-11-15 | 1976-05-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-16 | 1979-11-15 | 1980-05-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-16 | 1983-11-15 | 1984-05-16 | $7700.00 | Window Closed / Lapsed |