Control method and control apparatus for four-wheel drive vehicle

Patent metadata

Field	Value
Publication number	US-8972136-B2
Application number	US-201213559468-A
Country	US
Kind code	B2
Filing date	Jul 26, 2012
Priority date	Jul 28, 2011
Publication date	Mar 3, 2015
Grant date	Mar 3, 2015

Abstract

Discloses is a method of controlling a four-wheel drive vehicle equipped with a torque distribution device capable of changing a torque distribution amount for secondary driven wheels according to an input current to be applied thereto. This method comprises the steps of: applying, to the torque distribution device, a current value corresponding to a target torque distribution amount; and, performing a current changing control for increasing and reducing the input current to the torque distribution device. The step of performing a current changing control includes causing the input current to the torque distribution device to be temporarily increased to a value greater than the current value corresponding to the target torque distribution amount, and then returned to the current value corresponding to the target torque distribution amount, and repeating the temporary increasing of the input current at least at intervals of a predetermined time.

First claim

What is claimed is:

1. A method for controlling a four-wheel drive vehicle which comprises: a driving source; primary driven wheels; secondary driven wheels; and a torque distribution device capable of distributing a torque input thereinto from the driving source, not only to the primary driven wheels but also to the secondary driven wheels, and changing a torque distribution amount for the secondary driven wheels, according to an input current to be applied thereto, the method comprising the steps of:
determining a target torque distribution amount for the secondary driven wheels according to a running state of the vehicle;
applying, to the torque distribution device, a current value corresponding to the determined target torque distribution amount; and
when the vehicle is in a predetermined running state, performing a current changing control for increasing and reducing the input current to the torque distribution device,
wherein the step of performing a current changing control includes causing the input current to the torque distribution device to be temporarily increased to a value greater than the current value corresponding to the target torque distribution amount, and then returned to the current value corresponding to the target torque distribution amount, and repeating the temporary increasing of the input current at least at intervals of a predetermined time.

2. The method as defined in claim 1 , wherein the current changing control is prohibited when the target torque distribution amount for the secondary driven wheels is greater than a predetermined upper limit value.

3. The method as defined in claim 2 , wherein the current changing control is prohibited when the target torque distribution amount for the secondary driven wheels is less than a predetermined lower limit value.

4. The method as defined in claim 3 , wherein the input current temporarily increased under the current changing control is returned to the current value corresponding to the target torque distribution amount, before an amount of torque to be transmitted to the secondary driven wheels substantially changes along with the increase in the input current.

5. The method as defined in claim 1 , wherein the current changing control is prohibited when the target torque distribution amount for the secondary driven wheels is less than a predetermined lower limit value.

6. The method as defined in claim 5 , wherein the input current temporarily increased under the current changing control is returned to the current value corresponding to the target torque distribution amount, before an amount of torque to be transmitted to the secondary driven wheels substantially changes along with the increase in the input current.

7. The method as defined in claim 1 , wherein the input current temporarily increased under the current changing control is returned to the current value corresponding to the target torque distribution amount, before an amount of torque to be transmitted to the secondary driven wheels substantially changes along with the increase in the input current.

8. An apparatus for controlling a four-wheel drive vehicle which comprises: a driving source; primary driven wheels; secondary driven wheels; and a torque distribution device capable of distributing a torque input thereinto from the driving source, not only to the primary driven wheels but also to the secondary driven wheels, and changing a torque distribution amount for the secondary driven wheels, according to on an input current to be applied thereto, the apparatus comprising:
a controller operable to determine a target torque distribution amount for the secondary driven wheels according to a running state of the vehicle, and apply, to the torque distribution device, a current value corresponding to the determined target torque distribution amount, the controller having a function of, when the vehicle is in a predetermined running state, performing a current changing control for increasing and reducing the input current to the torque distribution device,

wherein the current changing control is configured to cause the input current to the torque distribution device to be temporarily increased to a value greater than the current value corresponding to the target torque distribution amount, and then returned to the current value corresponding to the target torque distribution amount, and repeat the temporary increasing of the input current at least at intervals of a predetermined time.

Assignees

• Yagi Yasushi
• Kawano Hiroto
• Nozu Tomohiro
• Kakita Akiyoshi
• Shigeta Ryohei
• Mazda Motor
• Jtekt Corp

Inventors

• Yagi Yasushi
• Kawano Hiroto
• Nozu Tomohiro
• Kakita Akiyoshi
• Shigeta Ryohei

Classifications

• B60K23/0808

  for varying torque distribution between driven axles, e.g. by transfer clutch · CPC title

• B60W2520/28

  Wheel speed · CPC title

• B60K23/04

  for differential gearing · CPC title

• B60K17/02

  characterised by arrangement, location, or kind of clutch · CPC title

• B60W50/06

  Improving the dynamic response of the control system, e.g. improving the speed of regulation or avoiding hunting or overshoot · CPC title