Traction distribution control system for four-wheel drive vehicle
AssigneeHitachi Unisia Automotive, Ltd.
InventorNobuyuki Ohtsu
Life of this patent
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Abstract
A traction distribution control system for a 4WD vehicle is so constructed as to carry out traction distribution control to increase distribution of traction to the driven wheels when a speed difference between the main driving wheels and the driven wheels exceeds a control threshold value, detect constant-speed run of the vehicle, and carry out correction control to correct the control threshold value in accordance with the wheel-speed difference when constant-speed run is detected.
Claims18
A four-wheel drive vehicle, comprising:
- a source of traction;
- a main path which serves to transfer traction;
- an auxiliary path branched from the main path, the auxiliary path serving to transfer traction;
- main driving wheels which receive traction from the source through the main path;
- driven wheels which receive traction through the auxiliary path;
- a clutch arranged in the auxiliary path, the clutch changing traction to be transferred to the driven wheels through a change in engaging force;
- a device which detects a speed of a vehicle body;
- a device which detect speeds of the respective wheels;
- and
- an ECU which provides to the clutch a control signal for carrying out the change in engaging force, the ECU being so programmed as to:
- calculate a control threshold value in accordance with the detected vehicle-body speed,
- carry out a traction distribution control to increase distribution of traction to the driven wheels when a difference in detected wheel speeds between the main driving wheels and the driven wheels exceeds the control threshold value,
- detect a constant-speed run of the vehicle, and
- carry out a correction control to correct the control threshold value in accordance with the difference in -detected wheel speeds when the constant-speed run is detected.
A four-wheel drive vehicle, comprising:
- a source of traction;
- a main path which serves to transfer traction;
- an auxiliary path branched from the main path, the auxiliary path serving to transfer traction;
- main driving wheels which receive traction from the source through the main path;
- driven wheels which receive traction through the auxiliary path;
- a clutch arranged in the auxiliary path, the clutch changing traction to be transferred to the driven wheels through a change in engaging force;
- means for detecting a speed of a vehicle body;
- means for detecting speeds of the respective wheels;
- and
- means for providing to the clutch a control signal for carrying out the change in engaging force, the providing means comprising:
- means for calculating a control threshold value in accordance with the detected vehicle-body speed,
- means for carrying out a traction distribution control to increase distribution of traction to the driven wheels when a difference in detected wheel speeds between the main driving wheels and the driven wheels exceeds the control threshold value,
- means for detecting a constant-speed run of the vehicle, and
- means for carrying out a correction control to correct the control threshold value in accordance with the difference in detected wheel speeds when the constant-speed run is detected.
A method of controlling traction distribution in a four-wheel drive vehicle with a traction source, main driving wheels, driven wheels, and a clutch, the method comprising:
- detecting a speed of a vehicle body;
- detecting speeds of the respective wheels;
- providing to the clutch a control signal for carrying out the change in engaging force;
- calculating a control threshold value in accordance with the detected vehicle-body speed;
- carrying out a traction distribution control to increase distribution of traction to the driven wheels when a difference in detected wheel speeds between the main driving wheels and the driven wheels exceeds the control threshold value;
- detecting a constant-speed run of the vehicle;
- and
- carrying out a correction control to correct the control threshold value in accordance with the difference in detected wheel speeds when the constant-speed run is detected.
Dependencies are inferred from the claim text.