EP0442500A2
Expired / Lapsed
EP
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Estimating road friction coefficient
Assignee: Akebono Brake Industry Co Ltd
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Filing: 1991-02-14
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Granted: —
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Expires: 2011-02-14
Abstract
Abstract A road surface friction coefficient estimating method and apparatus in an anti-lock control device for preventing locking of vehicle wheels during braking. The a road surface friction coefficient is estimated by comparing a deceleration of an estimated vehicle speed with a predetermined threshold value. The predetermined threshold value has different road surface friction coefficient values corresponding to different vehicle deceleration values. The braking hydraulic pressure is then repeatedly varied in accordance with signals indicative of the estimated road surface friction coefficient, signals indicative of the estimated vehicle speed, and one of the signals indicative of the slowest rear wheel speed and the front wheel speeds. <IMAGE>
Inventors
- 👤 Satomi Okubo
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 18:23
CPC Classifications
B; B60; B60T; B60T8/00; B60T8/17; B60T8/172; B60T8/176; B60T8/1763; B60T8/17636; B60T2210/00; B60T2210/10; B60T2210/12
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
85 words
A method of estimating a road surface friction coefficient for a running vehicle being braked, characterized by the steps of: setting an estimated vehicle speed (Vv) based on wheel speeds (Vw) of said running vehicle; setting at least one threshold value (VvG1, VvG2) representing predetermined road surface friction coefficients; calculating a deceleration (VvG) of said estimated vehicle speed (Vv); and estimating said road surface friction coefficient by comparing said deceleration (VvG) with said threshold value (VvG1, VvG2) and obtaining an estimated road surface friction coefficient.
Claim 2
Dependent Claim
62 words
The method according to claim 1, wherein said deceleration calculating step includes the steps of: setting a predetermined time period (△T); calculating a speed difference (△V) between said estimated vehicle speed (Vv) at a beginning and end of said predetermined time period (△T) during braking; and calculating said deceleration (VvG) by dividing said speed difference (△V) by said predetermined time period (△T).
Claim 3
Dependent Claim
60 words
The method according to claim 1, wherein said method is adapted to be used for an anti-lock control system for preventing locking of wheels of said running vehicle, said anti-lock system comprsing means (9, 10, 12, DV, HV) for repeatedly varying braking hydraulic pressure in accordance with electric signals indicative of a value of said estimated road surface friction coefficient.
Claim 4
Dependent Claim
55 words
The method according to claim 3, wherein means for repeatedly varying braking hydraulic pressure further comprises: means for setting a plurality of pressure increase rates for increasing said brake hydraulic pressure; and means for selecting one of said plurality of pressure increase rates in accordance with the value of said estimated road surface friction coefficient.
Claim 5
Dependent Claim
43 words
The method according to claim 4, wherein each of said plurality of pressure increase rates is defined by a time period in which said brake hydraulic pressure is increased and a respective time period in which said brake hydraulic pressure is held constant.
Claim 6
Dependent Claim
192 words
An anti-lock control device for preventing locking of vehicle wheels during braking, said anti-lock control device comprising: a plurality of detecting means (1,2,3,4) for detecting wheel speeds and providing wheel speed signals indicative thereof; first circuit means (11) for determining a slowest rear wheel speed from said wheel speed signals indicative of speeds of rear wheels and providing a slowest rear wheel speed signal indicative thereof; second circuit means (13) for determining a fastest wheel speed from said signals provided by said plurality of detecting means and providing a vehicle speed signal indicative of said fastest wheel speed; third circuit means (14) for calculating a vehicle deceleration in accordance with said vehicle speed signal and comparing said vehicle deceleration with predetermined vehicle decelerations to obtain an estimated road surface friction coefficient, said second circuit means providing an estimated road surface friction coefficient signal indicative of said estimated road surface friction coefficient; a plurality of fourth circuit means (9,10,12) for providing brake pressure control signals in accordance with said vehicle speed signal, said estimated road surface friction coefficient signal, and one of said slowest rear wheel speed signal and said wheel speed signals.
References Cited (Backward Citations)
No citation records indexed.
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