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Automotive four wheel steering system

  • US 4,941,542 A
  • Filed: 06/07/1989
  • Issued: 07/17/1990
  • Est. Priority Date: 10/01/1986
  • Status: Expired due to Fees
First Claim
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1. In an automotive vehicle having front and rear wheel pairs and a steering wheel drivingly coupled with the front wheel pair for steering the vehicle with respect to the direction of run of the vehicle, said steering wheel being rotatable in opposite directions from a neutral position at which the vehicle can run straightforward, a fluid-operated, four wheel steering system which comprises:

  • a front wheel steering mechanism including a front steering rod that is adapted to steer the front wheel pair in response to rotation of the steering wheel;

    a fluid-operated front cylinder means actuated in response to the rotation of the steering wheel from the neutral position, said front cylinder means including a front piston member that is mechanically coupled to the front steering rod for movement in response to rotation of the steering wheel, said front cylinder means having first and second front cylinder chambers positioned on opposite sides of said front piston member, said first front cylinder chamber having a volume that is adapted to be reduced when the steering wheel is rotated to turn the front wheel pair leftwards with respect to the direction of movement of the vehicle, and the second front cylinder chamber having a volume that is adapted to be reduced when the steering wheel is rotated to turn the front wheel pair rightwards with respect to the direction of movement of the vehicle;

    a fluid-operated rear cylinder means for steering the rear wheel pair for turning at least one rear wheel of the rear wheel pair with respect to the direction of straightforward run of the vehicle, said rear cylinder means including a first rear cylinder assembly and a second rear cylinder assembly, said first rear cylinder assembly being adapted to cause a right-hand rear wheel of the rear wheel pair to turn when supplied with a fluid medium and said second rear cylinder assembly being adapted to cause a left-hand rear wheel of the rear wheel pair to turn when supplied with a fluid medium;

    said front and rear wheel pairs being adapted to turn in the same direction;

    a fluid passage means for operatively coupling the front and rear cylinder means together to permit a fluid medium to be supplied from the front cylinder means to the rear cylinder means to thereby actuate the rear cylinder means, said fluid passage means including a first fluid passage that communicates the first front cylinder chamber with the first rear cylinder assembly for supplying fluid medium under pressure to the first rear cylinder assembly and a second fluid passage that communicates the second front cylinder chamber with the second rear cylinder assembly for supplying fluid medium under pressure to the second rear cylinder assembly; and

    a fluid medium accommodating means disposed in the rear cylinder means for accommodating a portion of the fluid medium being supplied from the front cylinder means to the fluid-operated rear cylinder means only when the pressure of the fluid medium in the front cylinder means increases such that the pressure in the rear cylinder means increases to a value greater than a predetermined value as a result of rotation of the steering wheel when the automotive vehicle is traveling at relatively low speeds, said fluid medium accommodating means being operable to accommodate a portion of the fluid medium independent of the turn of the rear wheel pair.

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