Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
1999-08-18
2001-11-20
Camby, Richard M. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C701S083000, C701S084000, C180S197000, C303S142000
Reexamination Certificate
active
06321154
ABSTRACT:
BACKGROUND INFORMATION
Drive slip control systems are known from the existing art in many variations. For example, European Patent No. 0 1 63 941 (corresponding to U.S. Pat. No. 4,625,824) describes a drive slip control system in which, when incipient slippage of at least one driven wheel is detected, that wheel is braked and/or the drive unit of the vehicle is caused to reduce its torque. In the low wheel rotation speed rangee, i.e. in the initial vehicle movement range, only the wheel which first exhibits incipient slippage is braked, while the other driven wheel, even if incipient slippage is present, remains unaffected until a threshold value for the rotation speed of the drive unit has been exceeded.
Although the vehicle's initial movement behavior has been considerably improved by this procedure, it is still not satisfactory in certain applications. This is evident especially from the fact that, for example on a sloping road surface, the vehicle can slide laterally if the second, uncontrolled wheel becomes unstable.
It is an object of the present invention to improve a drive slip control system, especially in the initial vehicle movement range, in terms of the driving comfort and/or stability of the vehicle.
German Patent No. 43 44 634 (corresponding to U.S. Pat. No. 5,696,683) describes a drive slip controller in which the torque demand or torque reduction of the drive is ascertained from vehicle resistance torques. If an instability occurs, the drive torque of the vehicle's drive unit is reduced by the engine controller to that torque demand, in order to reestablish stability at the driven wheels.
SUMMARY OF THE INVENTION
The present invention considerably improves a drive slip control system, especially in the initial vehicle movement range, in terms of the driving comfort and/or stability of the vehicle.
In particular, the definition of a reference engine speed instead of the torque demand established in the event of instability results in more harmonious initial vehicle movement, since the reference speed can be optimally defined—as a function of various operating variables such as vehicle resistance, minimum engine speed, optimum slip, and gear ratio—in a manner specifically adapted for the initial vehicle movement operation.
It is particularly advantageous in this context that in vehicles with manual transmission, stalling of the drive unit is effectively prevented.
As a result of the advantageous procedure during braking intervention, according to which braking force is built up at the wheel which first exhibits impermissible slip and is regulated to the optimum slip of the other wheel, lateral sliding is effectively prevented even on a sloping road surface. The reason is that the other wheel essentially always runs in stable fashion.
It is advantageous in particular that alternating breakaway of the driven wheels, i.e. alternating instability of the driven wheels, is prevented, since the braking force at the one wheel is reduced in the event of instability at the other, while that other wheel is braked only to the point of preventing breakaway of that wheel.
It is particularly advantageous if the reference speed control system and the braking intervention coact.
REFERENCES:
patent: 4625824 (1986-12-01), Leiber
patent: 5573315 (1996-11-01), Schmitt et al.
patent: 5688079 (1997-11-01), Bach et al.
patent: 5696683 (1997-12-01), Schäfer et al.
patent: 5732379 (1998-03-01), Eckert et al.
patent: 5754967 (1998-05-01), Inoue et al.
patent: 5864769 (1999-01-01), Inagaki et al.
patent: 5978726 (1999-11-01), Takeda et al.
Schmitt Johannes
Zoebele Andreas
Camby Richard M.
Kenyon & Kenyon
Robert & Bosch GmbH
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