Four-wheel steering system for vehicle

摘要

In a four wheel steering system, the rear wheel turning mechanism is connected to the front wheel turning mechanism by way of a rear wheel turning angle ratio changing mechanism which is mechanically connected to both the front wheel turning mechanism and the rear wheel turning mechanism and transmits the mechanical displacement input thereinto from the front wheel turning mechanism to the rear wheel turning mechanism to drive the same by an amount the ratio of which to the amount of mechanical displacement input into the rear wheel turning angle ratio changing mechanism gives a predetermined rear wheel turning angle ratio. The rear wheel turning angle ratio changing mechanism is controlled in such a way that, when the front wheels are turned from the neutral position in a middle vehicle speed range, makes the rear wheel turning angle ratio negative for a moment immediately after initiation of turning of the front wheels and thereafter turns the same positive.