When engagement of a lockup clutch is initiated, coupling of the lockup clutch is initiated in a state where a working fluid amount is sufficiently ensured by setting a condition that an engine rotation speed is higher than or equal to a limit engine rotation speed. Thus, it is possible to prevent rapid engagement of the lockup clutch. Here, the limit engine rotation speed is appropriately determined on the basis of a line pressure, and it is possible to reduce a delay of coupling of the lockup clutch by ensuring the working fluid amount while preventing rapid engagement of the lockup clutch.

A vehicle control apparatus for a vehicle including an automatic transmission having a torque converter provided with a lock-up clutch, and including a kick-down controller that performs kick-down control to change a transmission ratio to a low side and to increase a number of engine revolutions based on a kick-down request in accordance with an accelerator operation and a lock-up controller that performs lock-up disengagement control based on the kick-down request to set the lock-up clutch to a disengaged state according to meeting of a disengagement condition. When the kick-down request not during the kick-down control is called a normal kick-down request and the kick-down request during the kick-down control is called a second-time kick-down request, the lock-up controller performs lock-up disengagement control according to the second-time kick-down request based on the disengagement condition which is more eased than the disengagement condition used for the normal kick-down request.

In a vehicle equipped with a torque converter (4) having a lock-up clutch (3), learning control for obtaining a learning value (L_n) on the basis of meet-point information, with which the lock-up clutch (3) initiates torque transmission, is carried out. After acquiring the current learning detection value (M_n), a meet-point learning control unit (12c) calculates the current detection error (E_n) on the basis of the difference between the current learning detection value (M_n) and the previous learning value (L_(n1)) that is stored. When the current and previous detection errors (E_n) and (E_n1) have the same plus/minus sign, the current learning value correction amount is set to a larger value if the absolute value |(E_n1)| of the previous detection error (E_n1) is large than if the absolute value |(E_n1)| is small. The sum of the previous learning value (L_(n1)) and the current learning value correction amount is set as the present learning value (L_n).

In a vehicle on which a torque converter having a lock-up clutch is mounted between an engine and a transmission, a meet point learning controller is provided to perform learning control for obtaining a learning value based on information on a meet point at which the lock-up clutch starts torque transmission. The meet point learning controller estimates a LU transmission torque based on a difference between an engine torque signal value and a torque converter transmission torque when the lock-up clutch moves from a non-engaged state to an engaged state during traveling of the vehicle, and uses, as the meet point information, a meet point detection pressure at a time when the LU transmission torque estimated value is determined to have entered an upward trend.

In a vehicle equipped with a torque converter 4 having a lock-up clutch (3), learning control for obtaining a learning value (L_n) on the basis of meet-point information, with which the lock-up clutch (3) initiates torque transmission, is carried out. When the lock-up clutch (3) experiences a transition to an engaged state during travel, a meet-point learning control unit (12c) calculates an LU transmission torque estimate on the basis of the difference between the engine torque (engine torque signal value Te) and the torque converter transmission torque (.Math.Ne.sup.2). Excess clutch capacity is detected when the LU transmission torque estimate is greater than an excess capacity determination transmission torque threshold within a prescribed amount of time after an initial pressure (P_n) based on the learning value (L_n) is instructed. When excess clutch capacity is detected, a learning value correction that reduces the learning value (L_n) is carried out.

The present disclosure relates to a method for controlling a lock-up clutch of an automatic transmission. The method includes: a detecting step of detecting, by a controller, a current signal applied to a solenoid valve of an engaging element when a gear change operation begins; and a first increasing control step of controlling, by the controller, an amount of current that is applied to a solenoid valve of a lock-up clutch during an initial fill time period when it is determined that the current signal is applied to the solenoid valve of the engaging element. In particular, the solenoid valve of the engaging element is used to form a gear stage, and the controller increases the amount of current to a predetermined level for a predetermined period of time.

A vehicle lock-up clutch control device is provided to suppress engine racing when a lock-up clutch is engaged at the time a vehicle starts moving. The vehicle lock-up clutch control device is provided with a control unit that delays the rise in lock-up command pressure if a line pressure, which is the source pressure of the actual lock-up oil pressure, is rising when the lock-up clutch is engaged at the time the vehicle starts moving. The control unit executes a torque reduction in the engine at least during the delay in the lock-up command pressure.

A control device for an automatic transmission includes: a first engagement control section configured to bring the lockup clutch to a full engagement state after a rotation of the internal combustion engine is increased in a slip engagement state while a torque transmission capacity of the lockup clutch is increased, and a second engagement control section configured to add a predetermined capacity to the increased torque transmission capacity when the torque judging section judges an increase of the output torque of the internal combustion engine in a state where a sensed rotation speed difference in the slip engagement state of the engagement state of the first engagement control is increased to be equal to or greater than a first predetermined value, and then decreased to be equal to or smaller than a second predetermined value smaller than the first predetermined value.

A vehicle controller includes a lock-up clutch disposed to a power transmission path between an engine and a driving wheel, and a clutch configured to connect and disconnect the power transmission path, wherein at the time of switching driven traveling for causing a vehicle to travel by connecting the power transmission path and inertia traveling for causing the vehicle to travel by disconnecting the power transmission path, the lock-up clutch and the clutch are switched at switching start timings different from each other.

A vehicle lock-up clutch control device is provided to suppress engine racing when a lock-up clutch is engaged at the time a vehicle starts moving. The vehicle lock-up clutch control device is provided with a control unit that delays the rise in lock-up command pressure if a line pressure, which is the source pressure of the actual lock-up oil pressure, is rising when the lock-up clutch is engaged at the time the vehicle starts moving. The control unit executes a torque reduction in the engine at least during the delay in the lock-up command pressure.