Power steering device for four-wheel drive vehicle

• US 7,717,224 B2
• Filed: 01/10/2006
• Issued: 05/18/2010
• Est. Priority Date: 01/11/2005
• Status: Expired due to Fees

• Current Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Original Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Inventors: Kanazawa, Kazuo, Yoneda, Takeshi, Kiryu, Hiroyuki, Shibuya, Makoto, Yamazaki, Yoshinobu
• Primary Examiner(s): Morris; Lesley
• Assistant Examiner(s): Stabley; Michael R
• Application Number:
  US11/328,874
• Publication Number:
  US 20060169523A1
• Time in Patent Office: 1,589 Days
• Field of Search: 180/421, 180/422
• US Class Current: 180/421
• CPC Class Codes: B62D 5/06 fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
• CPC Class Codes: B62D 6/00 Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits means for initiating a change in direction B62D1/00; steering valves B62D5/06; combined with means for inclining the vehicle body or wheels on bends B62D9/00
• CPC Class Codes: B62D 6/008 Control of feed-back to the steering input member, e.g. simulating road feel in steer-by-wire applications

Abstract

The present invention offers a power steering device for a four-wheel drive, which includes: a first self-aligning torque estimation unit for estimating a self-aligning torque generated in a current vehicle behavior as a first self-aligning torque; a second self-aligning torque estimation unit for estimating a self-aligning torque that is to influence a subsequent vehicle behavior as a second self-aligning torque; a self-aligning torque change amount calculation unit for calculating a difference of the second self-aligning torque from the first self-aligning torque as a self-aligning torque change amount; and an assisting force correction unit for determining and outputting a corrected value of an assisting force to be generated for a steering operation based on the self-aligning torque change amount. Therefore, even when the self-aligning torque changes as the distribution of the front and rear driving power is variably controlled, a corresponding assisting force is generated, maintaining a natural steering feeling without causing an unpleasant sensation to the driver.

Claims

1. A power steering device for a four-wheel drive vehicle, in which driving force from an engine is controlled to be variably distributed to front and rear wheels, comprising:

a self-aligning torque estimation unit for estimating a self-aligning torque generated in a current vehicle behavior as a first self-aligning torque and for estimating a self-aligning torque that is to influence a subsequent vehicle behavior as a second self-aligning torque;

a self-aligning torque change amount calculation unit for calculating a difference of the second self-aligning torque from the first self-aligning torque as a self-aligning torque change amount; and

an assisting force correction unit for determining and outputting a corrected value of an assisting force to be generated for a steering operation based on the self-aligning torque change amount.

2. The power steering device according to claim 1, further comprising a front wheel side driving torque estimation unit for estimating a front wheel side driving torque that acts on the front wheels, wherein

the self-aligning torque estimation unit estimates the first self-aligning torque based on at least the front wheel side driving torque previously estimated by the front wheel side driving torque estimation unit, and estimates the second self-aligning torque based on at least the front wheel side driving torque currently estimated by the front wheel side driving torque estimation unit.

3. A power steering device for a four-wheel drive vehicle, in which driving force from an engine is controlled to be variably distributed to front and rear wheels, comprising:

a self-aligning torque estimation unit for estimating a self-aligning torque generated in a current vehicle behavior as a first self-aligning torque and, for estimating a self-aligning torque that is to influence a subsequent vehicle behavior as a second self-aligning torque, utilizing a received side slip angle signal, a received previous front wheel driving torque signal, a received front wheel side current time front wheel side driving torque signal, and a characteristic map on which the self-aligning torque versus the braking/driving force for various sideslip angles is plotted for the particular vehicle type;

a self-aligning torque change amount calculation unit for calculating a difference of the second self-aligning torque from the first self-aligning torque as a self-aligning torque change amount; and

an assisting force correction unit for determining and outputting a corrected value of an assisting force to be generated for a steering operation based on the self-aligning torque change amount.