US3744849A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Arrangement for measuring the speed of a vehicle in a brake control system of the vehicle
Assignee: Saab AB
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Filing: 1970-10-26
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Granted: 1973-07-10
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Expires: 1990-10-26
Abstract
Abstract In a brake control system of wheeled vehicles, particularly of motor cars, an arrangement measures the vehicle speed by means of an accelerometer of simple type to produce a signal representing the speed of a braked individual wheel relative to the vehicle speed. The wheel is intermittently braked to be temporarily freerunning without slip so that the true vehicle speed is repeatedly measured by an inductive or other speed transmitter. Furthermore, the vehicle speed is continuously, though inaccurately, measured by integration of the output of an accelerometer of a simple cheap type. This integrated output is repeatedly corrected by being updated with the true vehicle speed intermittently measured by the speed transmitter when the wheel is free-running. During those periods during which the wheel is braked and may be lagging (slipping), the measured wheel speed differs from the updated speed represented by the integrated and updated accelerometer output. By comparison of these two speed values, an electrical signal representing the slip is produced and may be used for temporarily releasing the brake means of the vehicle when slip occurs or at least when the ratio of slip to speed passes a predetermined limit value. Any accelerometer output representing a negative retardation, i.e. positive acceleration, is suppressed.
Inventors
- 👤 A Jonason
- 👤 G Granlund
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:50
CPC Classifications
B; B60; B60T; B60T8/00; B60T8/17; B60T8/176; B60T8/1761; B60T8/17613; B60T8/172; B60T8/32; B60T8/34; B60T8/42; B60T8/4208; B60T8/4225; G; G01; G01P; G01P3/00; G01P3/42; B60T2250/00; B60T2250/04
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
323 words
In a brake control system of a wheeled vehicle, an arrangement for measuring the speed of the vehicle, said arrangement including an electronic unit for indicating an electrical quantity representing the instantaneous value of the slip (lag) of a wheel of the vehicle during braking in dependence on the respective speeds of the vehicle and the individual wheel, which arrangement comprises an accelerometer which is stationary with respect to the vehicle producing an output representing the retardation of the vehicle during braking and which produces an inaccurate measurement of the speed of the vehicle; included in the electronic unit a circuit integrating said output and comparing the inaccurate vehicle-speed signal represented by the integrated accelerometer output with a correct linear vehicle speed-representing signal from a block composed of a plurality of circuits, the circuit of said electronic unit including an integrator receiving and updating circuit comparing the output of the integrator with the output of said block, whereby to process correct vehicle speedrepresenting pulses from a vehicle speed transmitter such as an inductive speed transmitter associated with an intermittently free-running wheel of the vheicle, wherein the latter signal updates the integrated accelerometer output to represent values substantially equal to those represented by the vehicle speed signal of the free-running wheel before an output representing the predicted vehicle speed is supplied to a block composed of a plurality of circuits for treatment of wheel-speedrepresenting pulses from a speed transmitter of an individual wheel to indicate an electrical magnitude of the slip of the appropriate wheel relative to an information received by such a block and representing the instantaneous speed of an individual wheel, said system further comprising a correction filter which senses and totals the pulsed error signals transmitted fRom the updating circuit to the integrator, the accumulated signal being compensated and timed and fed back to the accelerator output supplied to the integrator during the periods during which no updating signals are operative.
Claim 2
Dependent Claim
323 words
In a brake control system of a wheeled vehicle, an arrangement for measuring the speed of the vehicle, said arrangement including an electronic unit for indicating an electrical quantity representing the instantaneous value of the slip (lag) of a wheel of the vehicle during braking in dependence on the respective speeds of the vehicle and the individual wheel, which arrangement comprises an accelerometer which is stationary with respect to the vehicle producing an output representing the retardation of the vehicle during braking and which produces an inaccurate measurement of the speed of the vehicle; included in the electronic unit a circuit integrating said output and comparing the inaccurate vehicle-speed signal represented by the integrated accelerometer output with a correct linear vehicle speed-representing signal from a block composed of a plurality of circuits, the circuit of said electronic unit including an integrator receiving and updating circuit comparing the output of the integrator with the output of said block, whereby to process correct vehicle speedrepresenting pulses from a vehicle speed transmitter such as an inductive speed transmitter associated with an intermittently free-running wheel of the vheicle, wherein the latter signal updates the integrated accelerometer output to represent values substantially equal to those represented by the vehicle speed signal of the free-running wheel before an output representing the predicted vehicle speed is supplied to a block composed of a plurality of circuits for treatment of wheel-speedrepresenting pulses from a speed transmitter of an individual wheel to indicate an electrical magnitude of the slip of the appropriate wheel relative to an information received by such a block and representing the instantaneous speed of an individual wheel, said system further comprising a correction filter which senses and totals the pulsed error signals transmitted fRom the updating circuit to the integrator, the accumulated signal being compensated and timed and fed back to the accelerator output supplied to the integrator during the periods during which no updating signals are operative.
Claim 3
Dependent Claim
74 words
An arrangement as claimed in claim 1, wherein the correction filter includes at least a capacitor adapted to be charged by the error signals transmitted from the updating circuit to the integrator, a discharge resistor which in combination with the capacitor determines the filtering time on constant of the filter, a resistor controlling the amount of the filter output injected into the integrator input, and a diode which prevents discharging to the supply circuit.
Claim 4
Dependent Claim
267 words
A brake control system for a wheeled vehicle, in which for measuring the speed of the vehicle there are provided an accelerometer which is stationary with respect to the vehicle and is arranged to provide an output representative of the retardation of the vehicle during braking, being a signal to initiate a calculation of the speed of the vehicle, electronic means including a top-follower circuit which in turn includes an integrator circuit for receiving and integrating the said accelerometer''s output to produce a signal indicative of the speed of the vehicle, an updating circuit for the comparison of the said vehicle speed signal from the said integrator circuit with a signal indicative of the speed of a reference wheel, which is intermittently free-running, derived from a wheel speed transmitter associated with said reference wheel, whereupon the reference wheel speed signal updates the integrated accelerometer output in order that the speed represented by the latter signal becomes substantially equal to the reference wheel speed before an output from the said top-follower circuit representative of the predicted vehicle speed is applied to a number of electronic circuits included in said electronic means, each electronic circuit being associated with each individual wheel of the vehicle, and arranged to receive further information regarding the instantaneous wheel speed during braking of said individual wheel from a wheel speed transducer associated with said individual wheel, such that an output signal from the said electronic means is dependent on the said output of the top-follower circuit and the said further information and is indicative of the instantaneous slip ratio of the said individual wheel.
Claim 5
Dependent Claim
267 words
A brake control system for a wheeled vehicle, in which for measuring the speed of the vehicle there are provided an accelerometer which is stationary with respect to the vehicle and is arranged to provide an output representative of the retardation of the vehicle during braking, being a signal to initiate a calculation of the speed of the vehicle, electronic means including a top-follower circuit which in turn includes an integrator circuit for receiving and integrating the said accelerometer''s output to produce a signal indicative of the speed of the vehicle, an updating circuit for the comparison of the said vehicle speed signal from the said integrator circuit with a signal indicative of the speed of a reference wheel, which is intermittently free-running, derived from a wheel speed transmitter associated with said reference wheel, whereupon the reference wheel speed signal updates the integrated accelerometer output in order that the speed represented by the latter signal becomes substantially equal to the reference wheel speed before an output from the said top-follower circuit representative of the predicted vehicle speed is applied to a number of electronic circuits included in said electronic means, each electronic circuit being associated with each individual wheel of the vehicle, and arranged to receive further information regarding the instantaneous wheel speed during braking of said individual wheel from a wheel speed transducer associated with said individual wheel, such that an output signal from the said electronic means is dependent on the said output of the top-follower circuit and the said further information and is indicative of the instantaneous slip ratio of the said individual wheel.
Claim 6
Dependent Claim
107 words
A brake control system as claimed in claim 3 further comprising means for feeding back output signals from the said integrator circuit to the said updating circuit, and a voltage-sensing diode connected between the said updating circuit and the said integrator circuit such that when the said reference wheel speed signal is smaller than or equal to the said output from the integrator circuit, the updating circuit output represents zero, whereas if the said reference wheel speed signal exceeds the output of the said integrator circuit, the updating circuit output is a signal to update the integrator circuit output to equal the said first wheel speed signal.
Claim 7
Dependent Claim
35 words
A brake control system as claimed in claim 4 wherein for amplifying the said accelerometer output there is provided an amplifier which can only transmit signals of a polarity representing a retardation of the vehicle.
Claim 8
Dependent Claim
77 words
A brake control system as claimed in claim 4 wherein the said reference wheel speed signals are pulses, means being provided for converting the said pulses into pulses of constant time interval; and a filter which forms part of an amplifier that causes a simple exponential delay, adapted to sum the pulses, so that the output of this circuit corresponds to the top speed of the said reference wheel and thus to the speed of the vehicle.
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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) | 1976-07-09 | 1977-01-08 | 1977-07-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-09 | 1981-01-08 | 1981-07-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-09 | 1985-01-08 | 1985-07-10 | $7700.00 | Window Closed / Lapsed |