Torque split control system for a four wheel drive vehicle
First Claim
1. A driving force distribution control system for a vehicle, said driving force distribution control system comprising:
- a torque distributing unit including a primary drive means for transmitting a driving force from an engine of said vehicle to primary drive wheels of said vehicle, and a secondary drive means for transmitting a driving force from said engine to secondary drive wheels of said vehicle through a torque distributing clutch capable of varying driving force transmitted to said secondary drive wheels in response to a control signal;
a first sensing means for determining a measured wheel speed difference between a primary wheel speed of said primary drive wheels and a secondary wheel speed of said secondary drive wheels;
a second sensing means for determining a vehicle speed of said vehicle;
a first processing means for determining a correction quantity in accordance with said vehicle speed;
a second processing means for determining a corrected wheel speed difference which is a difference resulting from subtraction of said correction quantity from said measured wheel speed difference; and
a third processing means for determining a desired clutch engagement force in accordance with said corrected wheel speed difference, and for producing said control signal representing said clutch engagement force, said third processing means holding said desired clutch engagement force equal to zero when said measured wheel speed difference is less than said correction quantity.
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Accused Products
Abstract
A driving force distribution control system for a 4WD vehicle includes a torque distributing clutch for varying a driving force transmitted to secondary drive wheels such as front wheels in response to a control signal, one or more sensors for determining a vehicle speed, and a measured wheel speed difference between a sensed speed of primary drive wheels such as rear wheels and a sensed speed of the secondary drive wheels, and a controller for producing the control signal. The controller determines a correction quantity which increases as the vehicle speed increases, further determines a corrected wheel speed difference by subtracting the correction quantity from the measured wheel speed difference in order to eliminate an undesired influence of a tire diameter difference between the front and rear wheels, and produces the control signal in accordance with the corrected wheel speed difference.
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Citations
17 Claims
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1. A driving force distribution control system for a vehicle, said driving force distribution control system comprising:
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a torque distributing unit including a primary drive means for transmitting a driving force from an engine of said vehicle to primary drive wheels of said vehicle, and a secondary drive means for transmitting a driving force from said engine to secondary drive wheels of said vehicle through a torque distributing clutch capable of varying driving force transmitted to said secondary drive wheels in response to a control signal; a first sensing means for determining a measured wheel speed difference between a primary wheel speed of said primary drive wheels and a secondary wheel speed of said secondary drive wheels; a second sensing means for determining a vehicle speed of said vehicle; a first processing means for determining a correction quantity in accordance with said vehicle speed; a second processing means for determining a corrected wheel speed difference which is a difference resulting from subtraction of said correction quantity from said measured wheel speed difference; and a third processing means for determining a desired clutch engagement force in accordance with said corrected wheel speed difference, and for producing said control signal representing said clutch engagement force, said third processing means holding said desired clutch engagement force equal to zero when said measured wheel speed difference is less than said correction quantity. - View Dependent Claims (2, 8, 9, 10, 11, 12, 13, 14)
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3. A driving force distribution control system for a vehicle, said driving force distribution control system comprising:
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a torque distributing unit including a primary drive means for transmitting a driving force from an engine of said vehicle to primary drive wheels of said vehicle, and a secondary drive means for transmitting driving force from said engine to secondary drive wheels of said vehicle through a torque distributing clutch capable of varying driving force transmitted to said secondary drive wheels in response to a control signal; a first sensing means for determining a measured wheel speed difference between a primary wheel speed of said primary drive wheels and a secondary wheel speed of said secondary drive wheels; a second sensing means for determining a vehicle speed of said vehicle; a first processing means for determining a correction quantity in accordance with said vehicle speed; a second processing means for determining a corrected wheel speed difference which is a difference resulting from subtraction of said correction quantity from said measured wheel speed difference; and a third processing means for determining a desired clutch engagement force in accordance with said corrected wheel speed difference, and for producing said control signal representing said clutch engagement force, wherein said first processing means includes a means for increasing said correction quantity as said vehicle speed increases and said third processing means includes a means for increasing said desired clutch engagement force as said corrected wheel speed difference increases, and wherein said first processing means includes a means for increasing said correction quantity in proportion to said vehicle speed. - View Dependent Claims (4, 5, 6, 7)
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15. A driving force distribution control system for a vehicle, said driving force distribution control system comprising:
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a torque distributing unit including a primary drive means for transmitting a driving force from an engine of said vehicle to primary drive wheels of said vehicle, and a second drive means for transmitting driving force from said engine to secondary drive wheels of said vehicle through a torque distributing clutch capable of varying driving force transmitted to said secondary drive wheels in response to a control signal; a first sensing means for sensing a primary wheel speed of said primary drive wheels and a secondary wheel speed of said secondary drive wheels, and for determining a measured wheel speed difference between said primary and secondary wheel speeds; a second sensing means for determining a vehicle speed of said vehicle; and a controlling means for controlling an actual clutch engagement force of said torque distributing clutch in accordance with said measured wheel speed difference by generating said control signal such that said control signal represents a desired clutch engagement force, said controlling means including a basic processing means for receiving an input variable and for determining said desired clutch engagement force as a function of said input variable such that said desired clutch engagement force is equal to zero when said input variable is zero and such that said desired clutch engagement force increases from zero as said input variable increases from zero, said controlling means further including a dead band setting means for determining a correction quantity corresponding to a dead band in accordance with said vehicle speed, and for determining said input variable, which is a corrected wheel speed difference resulting from subtraction of said correction quantity from said measured wheel speed difference, said dead band setting means causing said basic processing means to make said desired clutch engagement force equal to zero when said measured wheel speed difference is equal to said correction quantity. - View Dependent Claims (16, 17)
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Specification