Suspension control system for automotive vehicle suspension suppressing bouncing

A method for controlling damping characteristics of front and rear vehicular suspension systems for front and rear vehicle wheels, each of which has damping characteristics which are variable at least between a first harder suspension mode and a second softer suspension mode according to a preselected suspension control parameter, comprising the steps of:

• providing a single road sensor which monitors roughness of the road surface and produces a road condition indicative signal having a value which varies depending on the roughness of the road surface, said road sensor having a first positional relationship relative to said front wheel and having a second positional relationship relative to said rear wheel;
• providing a vehicle speed sensor for monitoring vehicle speed and producing a vehicle speed signal indicative of the vehicle speed;
• detecting an irregularity of the road surface which has a magnitude greater than a predetermined criteria;
• controlling damping characteristics of said front suspension system to cause said front suspension system to operate in said first mode at a first timing relative to a time at which the irregularity of the road surface of the greater magnitude that said criteria is detected;
• and
• controlling damping characteristics of said rear suspension system to cause said rear suspension system to operate in said first mode at a second timing relative to a time at which the irregularity of the road surface of the greater magnitude that said criteria is detected;
• said first timing being determined based on said first positional relationship and on said vehicle speed;
• said second timing being determined based on said second positional relationship and on said vehicle speed.

A system for a vehicle, comprising:

• a vehicle wheel;
• a suspension system for suspending said vehicle wheel, said suspension system being variable in damping rate at least between a first softer damping characteristic mode and a second harder damping characterisic mode;
• a road sensor for monitoring roughness of a road surface on which said vehicle is travelling and producing a road condition indicative signal;
• a vehicle speed sensor for monitoring vehicle speed and producing a speed sensor signal having a value representative of the speed of the vehicle;
• and
• a controller for normally outputting a first control signal to said suspension system for causing said suspension system to operate in said softer damping characterisic mode, said controller being connected to receive said road condition indicative signal and determining the presence of an irregularity on said road surface based on said road condition indicative signal, and for outputting a second control signal to said suspension system at a first timing to cause said suspension system to operate in said harder damping characteristic mode when the presence of said irregularity is determined, said first timing being determined such that said suspension system is operated in said harder damping charcteristic mode at least after said wheel has passed over said irregularity, and said controller sending said first control signal to said suspension system at a second timing for causing said suspension system to operate in said softer damping characteristic mode, said second timing being determined such that said suspension is maintained in said harder damping characteristic mode for a certain period of time after said wheel has passed over said irregularity.

A system for a vehicle, comprising:

• front wheels;
• rear wheels;
• front and rear suspension systems for suspending the front and rear wheels, said suspension systems having damping characteristics which are variable at least between a first mode where relatively low damping characteristics are obtained and a second mode where relatively high damping characteristics are obtained, said front and rear suspension systems being variable independently of each other;
• a road sensor for monitoring a condition of a road on which said vehicle is travelling and producing a road condition indicative signal, said road sensor being located in a first positional relationship relative to said front wheels and a second positional relationship relative to said rear wheels;
• a vehicle speed sensor for monitoring vehicle speed and producing a vehicle speed indicative signal;
• and
• a controller for sending control signals to said front and rear suspension systems to cause said front and rear suspension systems to operate in said first and second modes, said controller normally sending control signals for causing said suspension systems to operate in said first mode, said controller being responsive to said road sensor for sending control signals to said front and rear suspension systems when said road condition indicative signal becomes greater than a predetermined value to indicate a road roughness of a predetermined amount, said control signal for causing said suspension systems to operate in said second mode being sent to said front suspension system at a first timing relative to a time when said road condition signal becomes greater than said predetermined value and being sent to said rear suspension system at a second timing relative to said time when said road condition signal becomes greater than said predetermined value, and said controller sending a signal to control said suspension systems to operate in said first mode at a third timing such that said suspension systems operate in said second mode at least for a short time after said wheels pass said roughness in order to prevent hunting.