Automotive suspension control system with vehicle speed-dependent damping characteristics
First Claim
1. A suspension control system for an automotive vehicle comprising:
- a damper means interpositioned between a vehicle body and a road wheel for absorbing, at least in part, relative displacement between the vehicle body and the road wheel, said damper means having variable damper characteristics;
a first sensor detecting roughness of the road surface and producing a first sensor signal having a value variable depending upon roughness of the road surface;
a second sensor detecting vehicle speed and producing a second signal having a value variable depending upon vehicle speed; and
a controller associated with said damper means for normally operating the latter in said first softer damping characteristics mode, said contrller being responsive to said second sensor signal for detecting the second sensor signal value within a given range representing a specific vehicle speed range, which given range being defined by an upper reference value representative of an upper vehicle speed criteria and a lower reference value representative of a lower vehicle speed criteria, comparing said second sensor signal value with said upper and lower reference values to determine whether the vehicle speed is within said given range or not, and varying variation characteristics of variable damping characteristics of said damper means in such a manner that, when said second sensor signal value is out of said given range, said controller derives sensing ability of road roughness and/or hardening magnitude of said variable damping characteristics damping means at relatively higher level, and when said second sensor signal value is within said given range, said controller derives sensing ability of road roughness and/or hardening magnitude of said variable damping characteristics damping means at relatively lower level.
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Accused Products
Abstract
A suspension control system includes a suspension system variable of stiffness and/or damping characteristics, a road sensor producing a road condition indicative signal and a controller for controlling the stiffness and/or damping characteristics of the suspension system depending upon the road condition indicative signal value and the vehicle speed indicative signal value. The controller is detective of the vehicle speed in a predetermined normal speed range which is defined by a lower speed criteria and an upper speed criteria, for generally maintaining the stiffness or damping characteristics of the suspension in relatively soft. The controller is detective of the vehicle speed indicative signal value smaller than the foregoing lower speed criteria to increase sensitivity of the road sensor and/or harden the suspension system at harder level than that in the normal speed range when the roughness of the road surface beyond a rough road criteria. Also, the controller is detective of the vehicle speed indicative signal value greater than the upper speed criteria for increasing sensitivity of the road sensor and/or harden the suspension system at harder level than that in the normal speed range when the roughness of the road surface beyond a rough road criteria, the relative displacement between a vehicle body and a road wheel, a vehicle speed sensor producing a vehicle speed indicative signal.
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Citations
17 Claims
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1. A suspension control system for an automotive vehicle comprising:
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a damper means interpositioned between a vehicle body and a road wheel for absorbing, at least in part, relative displacement between the vehicle body and the road wheel, said damper means having variable damper characteristics; a first sensor detecting roughness of the road surface and producing a first sensor signal having a value variable depending upon roughness of the road surface; a second sensor detecting vehicle speed and producing a second signal having a value variable depending upon vehicle speed; and a controller associated with said damper means for normally operating the latter in said first softer damping characteristics mode, said contrller being responsive to said second sensor signal for detecting the second sensor signal value within a given range representing a specific vehicle speed range, which given range being defined by an upper reference value representative of an upper vehicle speed criteria and a lower reference value representative of a lower vehicle speed criteria, comparing said second sensor signal value with said upper and lower reference values to determine whether the vehicle speed is within said given range or not, and varying variation characteristics of variable damping characteristics of said damper means in such a manner that, when said second sensor signal value is out of said given range, said controller derives sensing ability of road roughness and/or hardening magnitude of said variable damping characteristics damping means at relatively higher level, and when said second sensor signal value is within said given range, said controller derives sensing ability of road roughness and/or hardening magnitude of said variable damping characteristics damping means at relatively lower level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A suspension control system for an automotive vehicle comprising:
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a damper means interpositioned between a vehicle body and a road wheel for absorbing, at least in part, relative displacement between the vehicle body and the road wheel, said damper means having variable damper characteristics variable between a first damping mode in which said damping means produced the highest damping force, a second damping mode in which said damping means produces the lowest damping force and a third damping mode in which damping force produced is lower than that produced in said first damping mode and higher than that produced in said second damping mode; a first sensor detecting roughness of the road surface and producing a first sensor signal having a value variable depending upon roughness of the road surface; a second sensor dtecting vehicle speed and producing a second sensor signal having a value variable depending upon vehicle speed; and a controller for selecting one of said damping modes of said damping means and operating said damping means into said selected one of said damping mode, said controller comparing said second sensor signal value with a first upper and second lower vehicle speed threshold, said deriving a road roughness indicative value on the basis of said first sensor signal value and comparing said road roughness indicative value with a given reference value so as to select said first daming mode when said secopnd sensor signal value is greater than said first vehicle speed threshold or smaller than said second vehicle speed threshold and said road roughness indicative value is greater than said reference value and to select said third mode when said second sensor signal value is smaller than said first vehicle speed threshold and greater than said second vehicle speed threshold, and said road roughness indicative signal value is greater than said reference value. - View Dependent Claims (12, 13)
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14. A method for controlling damping characteristics of an automotive vehicle suspension system which includes a variable-damping-characteristics daming means, comprising the steps of:
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monitoring roughness of a road surface and producing a road roughness indicative signal having a value variable depending upon roughness of the road monitoring vehicle driving speed and producing a vehicle speed indicative signal having a value proportional to the vehicle speed comparing said vehicle speed indicative signal value with a first higher speed threshold and a second lower vehicle speed threshold for distinguishing whether said vehicle speed is within a predetermined vehicle speed range defined by said first and second speed threshold controlling said variable-damping-characteristics into a first soft suspension mode when said roughness indicative signal value is smaller than a given reference value, into a second hard suspension mode when said roughness indicative signal value is greater than said reference value and said vehicle speed is out of said predetermined range, and into a third medium mode which has damping characteristics intermediate between said first soft mode and second hard mode, when said roughness indicative signal value is greater than said reference value and said vehicle speed is within said predetermined range. - View Dependent Claims (15, 16, 17)
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Specification