Vehicle suspension control system and suspension control method

Abstract

When a vehicle approaches a corner, a microprocessor, responsive to a determination that a detected degree of roughness of the road surface corresponds to the most moderate roughness, sets the damping force for the vehicle suspension units, on the basis of the detected degree of roughness, vehicle speed and a radius of curvature and corner information from a navigation system. In the case of a determination that the detected degree of roughness does not correspond to the most moderate roughness, a damping level is set on the basis of the detected degree of roughness, vehicle speed and radius of curvature.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims, under 35 USC 119, priority of Japanese Application No. 2003-336127 filed Sep. 26, 2003 and Japanese Application No. 2003-346000 filed Oct. 3, 2003, the teachings of which are incorporated by reference herein, in their entirety, including the specifications, drawings and abstracts. Copending application of Fumiharu OGAWA, Ser. No. ______ (Attorney Docket No. AW-C463), entitled “SUSPENSION CONTROL SYSTEM AND SUSPENSION CONTROL METHOD FOR VEHICLE” and filed on even date herewith discloses and claims related subject matter. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a vehicle suspension control system and to a suspension control method. [0004] 2. Description of the Related Art [0005] According to the suspension control system disclosed in JP-A-9-114367, suspension control is initiated immediately before the automobile enters a turn around a corner in the cour...

AI Technical Summary

Benefits of technology

[0017] Accordingly, when the vehicle approaches the corner, if the road surface has a degree of roughness corresponding to a good road surface, the damping force of the suspension means before entering the turn at the corner is controlled in a manner corresponding to a good-road adjustment, thus favorably maintaining steering stability of the vehicle in turning the corner. On the other hand, if the degree of roughness of the road surface where the vehicle approaches the corner does not corresponding to a good road surface, the damping force of the suspension means is controlled in a manner corresponding to the bad-road adjustment when entering the corner, thus, in this case also, favorably maintaining steering stability and riding comfort of the vehicle in turning the corner.

[0018] In cornering if, upon entering the turn around the corner, after detection of a good road surface in the approach to a corner and output of a good road adjustment, the detected degree of roughness no longer corresponds to a good road surface, a bad-road adjustment to the damping force of the suspension means is calculated as above and output to the suspension means. Accordingly, when the vehicle approaches a corner, in the case where the road surface changes from a degree of roughness corresponding to a good road surface to a degree of roughness not corresponding to a good road surface, the damping force of the suspension means is thereafter controlled in accordance with the bad-road adjustment amount so that, in travel around the corner, steering stability and riding comfort are maintained.

[0032] Optionally, one or all of the adjustment calculating means may extract a roughness state component at a predetermined frequency from the signal for degree of roughness output by the roughness state detecting means and calculate the adjustment for damping force of the suspension means on the basis of that roughness state component.

[0043] As the vehicle approaches the corner, if the slip state of the road surface changes from a slip state corresponding to a good road surface to a slip state not corresponding to a good road surface, the damping force of the suspension means is changed from that for a good road surface to that for a bad road surface when entering the corner. Thus, in travel around the corner, the vehicle maintains favorable stability.

Problems solved by technology

However, in the above suspension control system, the corner information does not include information about the state of the road surface at the corner.

Accordingly, where the road surface at the corner is rough or slippery, for example, even if suspension control is previously effected as in the above, immediately before entering the corner, without taking into account the state of the road surface at the corner, the vehicle, after entering the corner turn, will have instability in steering and / or riding discomfort.

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