Driving force control apparatus and method for 4-wheel driving vehicle
First Claim
1. A driving force control apparatus for a 4-wheel drive vehicle including a differential system with a differential limit mechanism disposed between front or rear right and left wheels of the vehicle for restricting a slip of the wheels by controlling a driving force transmitted from the wheels to a road surface, comprising:
- wheel speed detection means for detecting individual rotational speeds of each of the four wheels;
slip detection means for detecting two relatively largest slip condition amounts, each slip condition amount indicating a magnitude of slip of an individual wheel according to a corresponding wheel rotational speed of one of the four wheels detected by said wheel speed detection means;
slip change rate calculation means for determining change rates of the two relatively largest slip condition amounts detected by said slip detection means;
slip change rate selection means for selecting the relatively smaller slip change rate of two slip change rates determined by said slip change rate calculation means; and
driving force control means for controlling the driving force according to the slip change rate selected by said slip change rate select means.
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Accused Products
Abstract
In a driving force control apparatus for a 4-wheel driving vehicle, a target driving torque is obtained based on a value determined by subtracting a feedback correction torque corresponding to a slip amount from a reference torque corresponding to a vehicle body speed. Slip is suppressed by a throttle control so that the engine output is reduced to the target driving torque. A retard command is output when the slip amount DVS and a slip rate GDVS are greater than predetermined values to control retarding of an ignition timing of the engine, thereby suppressing an abrupt slip. Further, the two greatest values of slip amounts of each of four wheels DVS1, DVS2, DVS3, and DVS4 are differentiated to determine slip rates GDVS1 and GDVS2, and the smaller of the slip rates GDVS1 and GDVS2 is used for control of ignition timing retarding. The apparatus causes a 4-wheel driving vehicle equipped with a limited slip differential (LSD) to provide a sufficient effect of the LSD and further suppresses the occurrence of an excessive slip.
21 Citations
27 Claims
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1. A driving force control apparatus for a 4-wheel drive vehicle including a differential system with a differential limit mechanism disposed between front or rear right and left wheels of the vehicle for restricting a slip of the wheels by controlling a driving force transmitted from the wheels to a road surface, comprising:
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wheel speed detection means for detecting individual rotational speeds of each of the four wheels; slip detection means for detecting two relatively largest slip condition amounts, each slip condition amount indicating a magnitude of slip of an individual wheel according to a corresponding wheel rotational speed of one of the four wheels detected by said wheel speed detection means; slip change rate calculation means for determining change rates of the two relatively largest slip condition amounts detected by said slip detection means; slip change rate selection means for selecting the relatively smaller slip change rate of two slip change rates determined by said slip change rate calculation means; and driving force control means for controlling the driving force according to the slip change rate selected by said slip change rate select means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. In a vehicle including a differential system with a differential limit mechanism, disposed between front or rear left and right wheels of the vehicle, for restricting slippage of the wheels by controlling a drive force transmitted from the wheels to a road surface, a driving force control method comprising the steps of:
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(a) detecting speeds of the wheels of the vehicle; (b) detecting two relatively largest slip condition amounts, each slip condition amount indicating a magnitude of slippage of a wheel according to a corresponding detected wheel speed; (c) determining change rates of each of the detected two relatively largest slip condition amounts; (d) selecting the relatively smaller one of the two determined change rates; and (e) controlling the driving force according to the selected change rate. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A driving force control apparatus for controlling a driving force transmitted from the wheels of a vehicle to a road surface, comprising:
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first means for detecting that a first condition is satisfied by detecting that a value derived from two relatively largest slip condition amounts is at least equal to a first predetermined value, each slip condition amount indicating a magnitude of slippage of one of the wheels according to a corresponding wheel speed; and second means for detecting that a second condition is satisfied by detecting that a relatively smaller of two change rates determined from each of the two relatively largest slip condition amounts is greater than a second predetermined value; and start means for initiating driving force control upon the first and second means detecting that the first and second respective conditions are satisfied. - View Dependent Claims (22, 23, 24, 25, 26, 27)
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Specification