Boots – shoes – and leggings
Patent
1994-06-27
1995-12-19
Teska, Kevin J.
Boots, shoes, and leggings
36442603, 303141, 180197, B60T 858
Patent
active
054774560
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a process for the reduction of disadvantageous effects of engine stall torques on the braking behavior of a vehicle which is equipped with a brake unit having an anti-lock control system. A circuit arrangement for carrying out the process, also, is part of the invention.
In the event of low coefficients of friction, the engine stall torque, which is transmitted from the driving engine through the gearing to the driven wheels, can very rapidly lead to a brake torque which is excessive relative to the running stability of the driven wheels. This holds true, in particular, of high-power driving engines and when a low gear has been applied. As a result of this brake torque caused by the driving engine, the steerability is greatly reduced for a vehicle with front-wheel drive. In case of rear-wheel drive, there is even the risk of skidding. This phenomenon starts immediately upon the reduction of the driving power and may even be boosted by the operation of the brakes.
From published German patent application No. DE 4040256 Al, a circuit arrangement for a brake unit with anti-lock control system is known which triggers a test cycle if and when, during a control cycle, the two wheels of a driven axle signal instability beyond a preset lag of time. Due to the test cycle, brake pressure is controlledly supplied into the wheel brake of the slower wheel, and the reaction of the driven wheels to the controlled supply of pressure is evaluated. In this manner, the control system determines whether or not the matter involves effects of an engine stall torque. If this is the case, then, due to the controlled supply of pressure into the wheel brake of the slower wheel, the speed of the second wheel of this axle is increased through the differential and, as a result, the running stability and the lateral control are remarkably improved.
It is, moreover, prior art to prevent the transmission of the engine stall torque to the wheels by interfering with the driving line, that is to say by disengaging the clutch. This is complicated, especially because the correct moment for clutching again is difficult to determine.
Another possible solution to the problem involves reducing the brake torque which is transmitted to the driven wheels by increasing the engine speed with the aid of a stall torque control system.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to develop a process of the type identified above which, without any interference with the drive of the vehicle, decisively reduces, in a simple way, the disadvantageous effects engine stall torques have on the braking behavior of a vehicle.
The present invention is based on the recognition that, at a very early moment, generally before any operation of the brake, engine stall torques have disadvantageous effects. Such a situation may come about as soon as the driver takes his foot off the accelerator pedal, and, for that matter, independently of any subsequent brake operation. The controlled supply of brake pressure into the wheel brakes of the driven wheels is then prevented as a result of the recognition of engine stall torques. The reapproach of the vehicle speed to the speed of the driven wheels is not hampered because there is no additional supply of brake pressure. It will be appreciated that the driven wheels are very rapidly conditioned to again provide elevated lateral guiding forces. With front-wheel drive, the steerability is preserved or restored again very quickly.
According to one advantageous embodiment of the present invention, a nearly equal brake slip at the driven wheels, exceeding a preset limit value or falling within a pre-established band, is taken as an indicator of the effect of engine stall torques. The supply of brake pressure is then prevented or brake pressure already existing is reduced until the vehicle speed again approximately coincides with the speed of the driven wheels.
Further features, advantages and possibilities of application of the present
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Determann Otto
Ehmer Norbert
Fennel Helmut
Schmidt Robert
Schwartz Jean-Claude
ITT Automotive Europe GmbH
Teska Kevin J.
Wieland Susan
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