Fluid-pressure and analogous brake systems – Speed-controlled – Torque sensing
Patent
1997-12-16
2000-04-18
Graham, Matthew C.
Fluid-pressure and analogous brake systems
Speed-controlled
Torque sensing
303191, 303195, 303196, B60T 832
Patent
active
060506520
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method of dampening vibrations in the drive system of a vehicle equipped with a control system, more particularly, an anti-lock system, traction slip control system, driving stability control system, or the like, wherein the rotational behavior of the individual wheels is sensed and analyzed. Circuitries for implementing the method are also comprised by the present invention.
Vibrations may occur in the drive system of an automotive vehicle due to elasticities in the drive trains, and take effect as torsional vibrations of the wheels in a circumferential direction, in particular of the driven wheels. Depending on their amplitude and frequency, these vibrations are felt in the vehicle and impair driving comfort. The vibrations may even be increased by control systems based on braking pressure modulation, in particular traction slip control systems and electronic differential locks.
An object of the present invention is to counteract vibrations and to dampen the vibrations at least to such an extent that they are not perceived by the driver and other occupants of the vehicle, and at least are not felt to be unpleasant.
SUMMARY OF THE INVENTION
It has been found that this object can be achieved by a method including that the vibrations in the drive system are determined by evaluation of the rotational behavior of the individual wheels and the torsional vibrations in a circumferential direction of the wheels, and that subsequently the vibrations are dampened by the introduction of braking pressure or by modulation of the braking pressure, which is introduced into the brakes of the individual wheels for slip control, as a function of the amplitude and the phase positioning of the torsional vibrations.
According to the present invention, the vibrations are effectively dampened by means of the component parts which are already provided in the control systems installed in a vehicle, without incurring additional expenditure, apart from the extension of the control electronics or the control program. This enhances the comfort and improves the control in many cases.
In one embodiment, the present invention is limited to a "passive" vibration dampening which is provided by delaying the pressure introduction into the wheel brakes of the respective wheel, which is responsive to slip control, until the commencement of the next leading half wave of the torsional vibration. Similarly, if necessary, the start of pressure reduction can be delayed until the commencement of the next trailing half wave of the torsional vibration. When the braking pressure is modulated by pressure-increase and pressure-reduction pulses in the control system, the start of the pressure-increase and pressure-reduction pulses is in each case postponed until the commencement of the next leading or trailing half wave for vibration dampening purposes.
Passive vibration dampening of this type fails when torsional vibrations appear as disturbing during a phase when the pressure is maintained constant. In this case, "active" vibration dampening is performed according to the present invention, irrespective of the braking pressure modulation calculated by the slip control system. Braking pressure is introduced into the wheel brake of the respective wheel at the beginning of a leading half wave of the torsional vibrations, and braking pressure is reduced accordingly at the beginning of a trailing half wave. Appropriately, the braking pressure is reduced by the amount by which it was previously increased.
In especially favorable circuitries for passive and active vibration dampening, a first nominal pressure component responsive to slip control and also a second nominal pressure component, which is used for passive or active dampening of the torsional vibrations and is produced by a vibration dampening logic circuit, are separately determined, superimposed and delegated, as a nominal value of the braking pressure, to a valve actuation control. The valve actuation control furnishes the signals
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patent: 5556174 (1996-09-01), Wiss et al.
patent: 5615935 (1997-04-01), Beyer et al.
patent: 5727856 (1998-03-01), Kost et al.
patent: 5868474 (1999-02-01), Abe et al.
Honus Klaus
Kolbe Alexander
Graham Matthew C.
ITT Manufacturing Enterprises Inc.
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