Clutch control method and device for vehicle with automatic transmission
First Claim
1. A clutch control method for a vehicle with an automatic transmission having a clutch for connecting and disconnecting power transmission of the automatic transmission, comprising steps of:
- restarting a fuel jet from a fuel cut state during deceleration; and
before said restarting step, changing the clutch from a direct coupling state into a semi-coupling state.
1 Assignment
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Accused Products
Abstract
In the fuel cut state during deceleration, an actual vehicle speed Vs is compared with a target vehicle speed Vso when the direct coupling state is changed into a semi-coupling state, or otherwise an actual engine rotational speed Ne is compared with a return engine rotational speed Neo at the return from fuel cut. Then, if Vs≦Vso or Ne≦Neo+K (K is a positive predetermined value), the clutch is changed from the direct coupling state into the semi-coupling state. Thus, shock due to torque change at the time of return from fuel cut can be reduced, and during the coast down, the fuel cut state can be maintained until the low rotational speed is attained. Both improvement of fuel economy and efficient use of engine brake can be attained. Engine stall can be prevented at the time of abrupt braking.
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Citations
6 Claims
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1. A clutch control method for a vehicle with an automatic transmission having a clutch for connecting and disconnecting power transmission of the automatic transmission, comprising steps of:
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restarting a fuel jet from a fuel cut state during deceleration; and before said restarting step, changing the clutch from a direct coupling state into a semi-coupling state.
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2. A clutch control method for a vehicle with an automatic transmission having a clutch for connecting and disconnecting power transmission of the automatic transmission, comprising a step of:
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changing the clutch from a direct coupling state into a semi-coupling state before a fuel jet is restarted from a fuel cut state during deceleration, said clutch control method further comprising steps of; inputting signals representative of an engine rotation speed (Ne) and a vehicle speed (Vs); calculating an engine rotation speed changing rate (dNe/dt) a vehicle speed changing rate (dVs/dt) on the basis of the engine rotation speed and the vehicle speed; obtaining a first correction value (Δ
Neo1) of the engine rotation speed at the restart of fuel on the basis of the engine rotation speed changing rate (dNe/dt);obtaining a second correction value (Δ
Neo2) of the engine rotation speed at the restart of fuel on the basis of the vehicle speed changing rate (dVs/dt);comparing the first correction value (Δ
Neo1) with the second correction value (Δ
Neo2) and adopting the larger one as a third correction value (Δ
Neo) of the engine rotation speed at the restart of the fuel;correcting a predetermined engine rotation speed (Neo) at the restart of the fuel in accordance with the third correction value (Δ
Neo); andchanging the clutch from a direct coupling state into a semi-coupling state if the engine rotation speed (Ne) is smaller than the corrected engine rotation speed at the restart of the fuel. - View Dependent Claims (3)
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4. A clutch control device for a vehicle with an automatic transmission having a clutch for connecting and disconnecting power transmission of the automatic transmission, comprising:
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a clutch state determination means for comparing, in a fuel cut state during deceleration, one of an actual vehicle speed (Vs) with a target vehicle speed (Vso), and an actual engine rotational speed (Ne) with an engine rotational speed (Neo) at a return from the fuel cut state; and clutch control means for changing the clutch from a direct coupling state into a semi-coupling state if the actual vehicle speed (Vs) is less than or equal to the target vehicle speed (Vso), or if the actual engine rotational speed (Ne) is less than or equal to the engine rotational speed (Neo) at the return from the fuel cut state plus a first positive predetermined value. - View Dependent Claims (5)
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6. A clutch control method for a vehicle with an automatic transmission having a clutch for connecting and disconnecting power transmission of the automatic transmission, comprising steps of:
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comparing, in a fuel cut state during deceleration, one of an actual vehicle speed with a target vehicle speed, and an actual engine rotational speed with an engine rotational speed at a return from the fuel cut state; and changing the clutch from a direct coupling state into a semi-coupling state when the actual vehicle speed is less than or equal to the target vehicle speed, or when the actual engine rotational speed is less than or equal to the engine rotational speed at the return from the fuel cut state plus a positive predetermined value.
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Specification