Control system for four-wheel drive vehicle

• US 8,731,794 B2
• Filed: 12/13/2011
• Issued: 05/20/2014
• Est. Priority Date: 12/22/2010
• Status: Active Grant

• Current Assignee: Continental Automotive GmbH (Continental AG)
• Original Assignee: Continental Automotive GmbH (Continental AG)
• Inventors: Kim, Gyu Tak
• Primary Examiner(s): Tarcza, Thomas
• Assistant Examiner(s): ALHARBI, ADAM MOHAMED
• Application Number:
  US13/997,331
• Publication Number:
  US 20130325276A1
• Time in Patent Office: 889 Days
• Field of Search: None
• US Class Current: 701/69
• CPC Class Codes: B60K 17/35 including arrangements for suppressing or influencing the power transfer, e.g. viscous clutches differential gearing with locking devices F16H48/20
• CPC Class Codes: B60K 17/3505 with self-actuated means, e.g. by difference of speed
• CPC Class Codes: B60K 23/08 for changing number of driven wheels , for switching from driving one axle to driving two or more axles B60K17/3515 takes precedence
• CPC Class Codes: B60K 23/0808 for varying torque distribution between driven axles, e.g. by transfer clutch
• CPC Class Codes: B60W 2720/403 between front and rear axle
• CPC Class Codes: B60W 2720/406 between left and right wheel

Abstract

In a control system for a four-wheel drive vehicle, when the four-wheel drive vehicle is four-wheel driven full time (that is, at all times), the difference in rotation of each wheel occurring due to the difference in air pressure within each tire, is differentiated from the difference in rotation of each wheel occurring due to cornering or the state of the road surface, and is correspondingly corrected so as to distribute the driving force to the four wheels. Thus, even if the difference in rotation of each wheel occurs due to the air pressure within each tire, the malfunction in which four-wheel driving is controlled based on the erroneous determination that the difference in rotation of each wheel is due to cornering or the state of the road surface can be prevented from occurring.

Claims

1. A control system for a four-wheel drive vehicle, the control system comprising:

a speed change part configured to transfer a driving force from an engine of the vehicle, and to output a speed change driving force through a specific gear depending on an adjustment status of an electromagnetic valve;

a transfer case part configured to transfer the speed change driving force from said speed change part and to drive either a rear wheel drive shaft of the vehicle or a front wheel drive shaft of the vehicle through an operation of a built-in motor;

a tire pressure sensing part installed to measure an air pressure in each tire of the vehicle; and

an electronic control part configured to calculate the rotations of the corresponding tire according to the measured tire air pressure value provided by said tire pressure sensing part, to compare counted rotations with actual rotations of the corresponding tire to judge whether the corresponding tire exhibits a rotation difference, and, when the respective wheel exhibits a rotation difference arising from a tire air pressure difference, to output control signals for the operation and control of said transfer case to distribute said speed change driving force, so as to offset the rotation difference.

2. The control system according to claim 1, wherein said electronic control part comprises:

a Tire Pressure Monitor System connected to receive the measured tire air pressure value from said tire pressure sensing part and a Transfer Case Control Unit configured to communicate with said TPMS and to receive the measured tire air pressure value for each wheel, and, based on the value, to judge whether the corresponding wheel has the rotation difference due to the tire air pressure difference, and to output a control signal according to the judgment result for the operation and control of said transfer case.

3. The control system according to claim 1, wherein, if the rotation difference of the corresponding wheel exceeds a preset threshold, said electronic control part outputs a control signal for operating and controlling said transfer case to distribute the speed change driving force, so as to offset the generated rotation difference.

4. The control system according to claim 1, wherein said electronic control part is configured to calculate a dynamic radius of the corresponding wheel according to the measured tire air pressure value provided by said tire pressure sensing part, and then to utilize the calculated dynamic radius to calculate the rotations of the corresponding wheel.

5. The control system according to claim 1, which further comprises a wheel sensing part disposed at one side of each wheel and used to determine the actual rotations.

6. The control system according to claim 1, wherein said electronic control part is configured to receive a measured air pressure value of each tire through a wireless link.

7. The control system according to claim 6, wherein said tire pressure sensing part comprises:

a tire pressure sensor installed at an inner side of said tire and used to measure the air pressure of the corresponding tire; and

a wireless communication module for wirelessly transferring the measured air pressure value of tire to said electronic control part.