Boots – shoes – and leggings
Patent
1990-07-02
1994-05-17
Black, Thomas G.
Boots, shoes, and leggings
180197, 303 95, 303100, B60T 860, B60T 882
Patent
active
053133919
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a drive slip control system including a slippage control circuit which forms a reference value that corresponds to the vehicle speed from the wheel speed signals of the non-driven wheels. The sensor signals of the driven wheels are compared to this reference value, and if the sensor signal of at least one of the driven wheels exceeds the reference value by a prescribed slippage, a control signal which depends on the reference value is generated.
When drive slip control systems are used, it is known to derive from the non-driven wheels a reference value which corresponds to the vehicle speed, for example, by forming an average value. If the speed of one of the driven wheels deviates from this reference value by a certain percentage, a slippage signal is generated which causes a braking to be applied to the corresponding wheel. If both wheels spin, the engine speed is reduced in addition.
SUMMARY OF THE INVENTION
In addition to a first factor calculated only as a fraction of the reference speed, the slippage value includes a second factor which is a constant value and a third factor which depends upon the vehicle acceleration.
Allowing for vehicle acceleration increases traction whereas introducing a constant factor b has the advantage of providing sufficient drive slip for optimal traction even when departing at a low acceleration. If then an additional factor is added which depends upon the square of the reference speed, the wheel tolerances have a less negative effect.
It is also possible to introduce the operator's action on the formation of a slippage threshold and, hence, on the adjustment of traction and stability.
A substitute value for the operator's action can be introduced in case this information is not available.
BRIEF DESCRIPTION OF THE DRAWING
The sole FIGURE is a schematic diagram of the regulating system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The sensors 1 and 2 for the non-driven wheels supply signals which correspond to the wheel speed to the average former 3 which generates a reference value V.sub.F that corresponds to the vehicle speed. The sensors 4 and 5 of the driven wheels provide wheel speed signals V.sub.R to blocks 6 and 7 to which the reference value V.sub.F is also supplied. The signals V.sub.R are compared to V.sub.F in the blocks and control signals are generated when the wheel speed V.sub.R exceeds the reference speed V.sub.F by a threshold value .lambda.. This value .lambda. is defined by the following relation. ##EQU1## where
FP is the pedal position provided by the operator. It can vary between 0 and 1,
a can range between 0.01 and 0.04, e.g. 0.03,
b can range between 0.5 and 10 km/h, e.g. 1 km/h,
c can range between 0.5.times.10.sup.4 and 5.times.10.sup.4 km/h, e.g. 1.times.10.sup.4 km/h,
d can range between 0 and 4 g e.g. 0.2 g and
e can range between 0.1/sec and 1.0/sec, e.g. 0.3/sec.
The first factor a V.sub.F is formed in blocks 6 and 7 and the second factor represented by addend b is supplied to terminals 8 and 9. The third factor represented by the expression ##EQU2## is formed in a differentiating and substracting block 10 and the fourth factor represented by the expression ##EQU3## is formed in a block 11. The signal FP representing the position of the accelerator pedal is provided by a pedal position sensor 16. If the wheel speed value V.sub.R exceeds the reference speed value V.sub.F by the above indicated threshold value .lambda., however variable, a control signal is generated in blocks 6 and 7 and the corresponding brakes 13 or 14 are operated, for example, by applying pressure through control devices 17 or 18. If blocks 6 and 7 both supply a control signal, the engine torque is reduced at block 15.
1. Drive slip control system for a vehicle having two driven wheels, two non-driven wheels, brakes associated with said wheels, an operator controlled accelerator pedal, and an engine which develops torque, said system comprising wheels, non-driven wheels, /dt, factor which is a fraction of
REFERENCES:
patent: 4484280 (1984-11-01), Brugger et al.
patent: 4681374 (1987-07-01), Nakamura et al.
patent: 4763263 (1988-08-01), Leiber
patent: 4768608 (1988-09-01), Hrovat
patent: 4771850 (1988-09-01), Matsuda
patent: 4825371 (1989-04-01), Hoashi et al.
patent: 4933856 (1990-06-01), Leiber
Meissner Manfred
Schafer Jochen
Schmitt Johannes
Sigl Alfred
Black Thomas G.
Park Collin W.
Robert & Bosch GmbH
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