Suspension control system for automotive vehicle

Claim 2

A suspension control system for an automotive vehicle, comprising: a) at least one shock absorber, interposed between a vehicle body and a road wheel, having a piston member and a damping force coefficient varying means operatively changing its position in response to a control signal so that a damping force coefficient of at least one or both extension and contraction stroke sides of the piston member is set to a target damping coefficient effecting position according to its input control signal; b) at least one sprung mass acceleration detecting means for detecting a vertical sprung mass acceleration and outputting a vertical sprung mass acceleration signal indicative thereof; c) at least one sprung mass vertical velocity determining means comprising a digital type low pass filter type integrator, for integrating the vertical sprung mass acceleration signal to derive a vertical sprung mass velocity signal; d) band pass filtering means for passing only a signal frequency component of either the vertical sprung mass acceleration signal or the vertical sprung mass velocity signal whose frequency falls in a predetermined frequency region having an inherent sprung mass resonance frequency as its center frequency; e) setting means for calculating a threshold value for the vertical sprung mass velocity signal value; f) determining means for determining whether the vertical sprung mass velocity signal value derived using said band-pass filtering means is below the threshold value; and g) controlling means for outputting the control signal to the damping coefficient varying means according to a result of the determination of the determining means so as to control the damping coefficient to the target damping force coefficient.

Claim 3

A suspension control system for an automotive vehicle as set forth in claim 1, wherein said band pass filter comprises a high pass filter which is arranged at a stage before the integrator and a low pass filter which is installed at a stage after the integrator.

Claim 4

A suspension control system for an automotive vehicle as set forth in claim 1, wherein said at least one shock absorber comprises four shock absorbers interposed respectively between a vehicular body and front and rear tire wheels.

Claim 5

A suspension control system for an automotive vehicle as set forth in claim 1, wherein said band pass filter is arranged at a stage after the integrator.

Claim 6

A suspension control system for an automotive vehicle as set forth in claim 3, wherein the predetermined frequency region is 0.5 Hz through 3 Hz.

Claim 7

A suspension control system for an automotive vehicle as set forth in claim 1, wherein said band pass filter is comprises a high pass filter and low pass filter.

Claim 8

A suspension control system for an automotive vehicle as set forth in claim 4, wherein both said high pass and low pass filters are connected in series with each other at a stage after the integrator.

Claim 9

A suspension control system for an automotive vehicle as set forth in claim 7, which further includes a gain adjuster which serves to correct the gain of the band-pass filtered signal indicating the sprung mass speed.

Claim 10

A suspension control system for an automotive vehicle as set forth in claim 8, the gain is expressed as n 2 .

Claim 11

A suspension damping force controlling apparatus, comprising: a) at least one shock absorber, interposed between a vehicle body and a road wheel, having a piston member and a damping force coefficient varying means operatively changing its position in response to a control signal so that a damping force coefficient of at least one or both extension and contraction strokes of the piston member is set to a target damping coefficient effecting position according to its input control signal; b) at least one sprung mass acceleration detecting means for detecting a vertical sprung mass acceleration and outputting a vertical sprung mass acceleration signal indicative thereof; c) at least one sprung mass vertical velocity determining means for integrating the vertical sprung mass acceleration signal to derive a vertical sprung mass velocity signal indicative thereof; d) band pass filtering means for passing only a signal frequency component of either the vertical sprung mass acceleration signal or the vertical sprung mass velocity signal whose frequency falls in a predetermined frequency region defined thereby with an inherent sprung mass resonance frequency as a center; e) setting means for calculating a threshold value for the vertical sprung mass velocity signal value; f) determining means for determining whether the vertical sprung mass velocity signal value derived through the band-pass filtering means is below the threshold value; g) controlling means for outputting the control signal to the damping coefficient varying means according to a result of the determining means so as to control the damping coefficient to the target damping force coefficient; and h) gain compensating means for compensating a gain reduction and phase delay of the band-pass filtering means in the vicinities of its cut-off frequencies.

Claim 12

A suspension damping force controlling apparatus, comprising: a) at least one shock absorber, interposed between a vehicle body and a road wheel, having a piston member and a damping force coefficient varying means operatively changing its position in response to a control signal so that a damping force coefficient of at least one or both extension and contraction strokes of the piston member is set to a target damping coefficient effecting position according to its input control signal; b) at least one sprung mass acceleration detecting means for detecting a vertical sprung mass acceleration and outputting a vertical sprung mass acceleration signal indicative thereof; c) at least one sprung mass vertical velocity determining means for integrating the vertical sprung mass acceleration signal to derive a vertical sprung mass velocity signal indicative thereof; d) band pass filtering means for passing only a signal frequency component of either the vertical sprung mass acceleration signal or the vertical sprung mass velocity signal whose frequency falls in a predetermined frequency region defined thereby with an inherent sprung mass resonance frequency as a center; e) setting means for calculating a threshold value for the vertical sprung mass velocity signal value; f) determining means for determining whether the vertical sprung mass velocity signal value derived through the band-pass filtering means is below the threshold value; g) controlling means for outputting the control signal to the damping coefficient varying means according to a result of the determining means so as to control the damping coefficient to the target damping force coefficient; and h) gain compensating means for compensating a gain reduction and phase delay of the band-pass filtering means in the vicinities of its cut-off frequencies.

Claim 15

In a suspension having a shock absorber operatively interconnecting a vehicle body and a road wheel, a damping force control arrangement comprising: damping force coefficient varying means which is responsive to a control signal for setting a damping force coefficient for one or both of extension and contraction strokes of the shock absorber to a target damping coefficient; an accelerometer for detecting an absolute vertical acceleration of a vehicle body and producing a first signal indicative thereof; means for integrating the first signal and deriving a second signal indicative of vertical velocity; band pass filtering means for filtering said second signal and for passing a third signal having a frequency which falls in a predetermined frequency region having an inherent sprung mass resonance frequency as its center frequency, said band pass filtering means having first and second cut-off frequencies; means for calculating a threshold value for the vertical sprung mass velocity signal value; means for comparing the third signal with the threshold value; means for outputting the control signal to the damping coefficient varying means in accordance with the comparison of the third signal with the threshold value; and gain compensating means for compensating for a gain reduction and phase delay of the band-pass filtering means in the vicinities of the first and second cut-off frequencies.

Claim 16

In a suspension having a shock absorber operatively interconnecting a vehicle body and a road wheel, a damping force control arrangement comprising: damping force coefficient varying means which is responsive to a control signal for setting a damping force coefficient for one or both of extension and contraction strokes of the shock absorber to a target damping coefficient; an accelerometer for detecting an absolute vertical acceleration of a vehicle body and producing a first signal indicative thereof; means for integrating the first signal and deriving a second signal indicative of vertical velocity; band pass filtering means for filtering said second signal and for passing a third signal having a frequency which falls in a predetermined frequency region having an inherent sprung mass resonance frequency as its center frequency, said band pass filtering means having first and second cut-off frequencies; means for calculating a threshold value for the vertical sprung mass velocity signal value; means for comparing the third signal with the threshold value; means for outputting the control signal to the damping coefficient varying means in accordance with the comparison of the third signal with the threshold value; and gain compensating means for compensating for a gain reduction and phase delay of the band-pass filtering means in the vicinities of the first and second cut-off frequencies.