Toyota Jidosha Kabushiki Kaisha

Denso Corporation

Nippon Soken, Inc.

Yasumichi Inoue

Zenichiro Mashiki

Haruyuki Urushihata

Noboru Takagi

Yoshihito Moriya

Mitsuhiro Nomura

Hiroshi Watanabe

Masayoshi Hattori

Akihiko Takenaka

Masaomi Inoue

Tsukasa Abe

Kenji Yamamoto

Eiji Isobe

Yuuichi Takemura

Takayuki Inohara

Toshikazu Tanaka

A rotational speed control apparatus for an engine is provided. The engine configured to drive a compressor that compresses a cooling medium for air conditioning. The rotational speed control apparatus includes electronic control unit. The electronic control unit is configured to: (a) correct a torque of the engine through feedback in accordance with a deviation between a rotational speed during idle operation and a target rotational speed; (b) (i) calculate a load torque of the compressor, and (ii) correct the calculated load torque through feedback in accordance with a deviation between the rotational speed of the engine and the target rotational speed and correct a required value of the torque of the engine in accordance with the corrected load torque, in a predetermined period from a start of a changeover between a driven state of the compressor and a stopped state of the compressor.

Engine rotational speed control apparatus

An object of the present invention is to enhance precision of air-fuel ratio control after return from fuel cut in a control device for an internal combustion engine that has a plurality of fuel injection modes, and performs calculation of a fuel injection amount by a method corresponding to an injection mode in use. For this object, the control device for an internal combustion engine the present invention provides normally determines the injection mode in response to an operation state, but designates a specific injection mode with a higher priority than the injection mode determined in response to the operation state at a time of return from fuel cut. For a predetermined time period after the return from fuel cut, the control device prohibits the injection mode from being changed in response to the operation state, and keeps fuel injection according to the designated specific injection mode.

Control device for internal combustion engine

An ECU executes a program including the steps of: detecting engine speed NE (S); and stopping power supply to an electric motor of an intake VVT mechanism (S), if engine speed NE is equal to or lower than a threshold value NE (0) (YES at S).

Variable valve timing apparatus and control method therefor

If it is necessary to rapidly change a phase of an intake camshaft and an intake VVT mechanism relatively slow in responsiveness as it is associated with an 'A' bank of a V-type, 8-cylinder engine is in operation for at least a predetermined period of time, an ECU executes a program including the step of controlling intake VVT mechanisms to operate those associated with both the 'A' bank and a &#x201c;B&#x201d; bank.

Device and method for controlling internal combustion engine

An ECU executes a program including the step of stopping power supply to an electric motor if a phase of an intake valve is in a first region between the most retarded angle and CA. In the case where the phase of the intake valve is in the first region, the rotational speed of relative rotation between the output shaft of the electric motor and a sprocket is reduced at reduction gear ratio R thereby to vary the phase of the intake valve. In the case where the phase of the intake valve is in a second region between CA and the most advanced angle, the rotational speed of the relative rotation is reduced at reduction gear ratio R thereby to vary the phase of the intake valve.

At the time of reference position learning for ensuring accuracy in detecting a valve timing, an operation amount of an actuator is set such that intake valve phase changes to a position of most retarded angle as a reference phase. When the intake valve phase reaches the most retarded angle and the change in the intake valve phase stops (YES at S), it is determined that the intake valve phase has reached the reference phase and the learning is terminated normally. If the learning operation does not end normally even after the time lapse from the start of learning exceeds a limit time Tlmt, the reference position learning is terminated forcibly (YES at S), and power supply to the actuator is stopped. Thus, power consumption can be reduced and the apparatus can be protected at the time of reference position learning.

Variable valve timing apparatus and control method thereof

An ECU executes a program including the steps of: controlling, when the phase of an intake valve is a phase advanced relative to a threshold value CA (FF) (NO in S), an electric motor operating an intake VVT mechanism by feedback control (S); and controlling, when the phase of the intake valve is a phase retarded relative to the threshold value CA (FF) (YES in S), the electric motor by feed-forward control (S). Under the feed-forward control, a duty command value is output that is smaller than an upper limit of a duty command value under the feedback control.

In a variable valve timing apparatus having a VVT mechanism in each of a plurality of banks, start of a valve timing control is not permitted until reference position learning of valve timing is completed in the corresponding bank and in other banks. Accordingly, the plurality of banks come to have matching valve timing setting at the time of valve timing control, whereby variation in the amount of air introduced to cylinders can be suppressed, and satisfactory combustion characteristics can be maintained.

Variable valve timing apparatus

A valve timing control is executed by an ECU that controls an engine and an electric-motor ECU that controls an electric motor. The ECU and the electric-motor EDU serve different functions. The ECU sets the target phase of an intake valve based on the engine operating state, and prepares a rotational speed command value for the electric motor that serves as an actuator such that a phase feedback control loop, in which the intake valve phase is caused to match the target phase, is formed. The electric-motor EDU forms a feedback control loop for the motor speed, in which the electric power supplied to the electric motor is controlled such that the electric motor rotates in accordance with the rotational speed command value.

Variable valve timing system

An ECU transmits a pulsed operation command signal, indicating operation commands for an electric motor used as a VVT actuator, to an electric-motor EDU. The electric-motor EDU recognizes the combination of the direction in which the actuator should be operated (actuator operation direction) and the control mode based on the duty ratio of the operation command signal, and the rotational speed command value based on the frequency of the operation command signal. The electric-motor EDU controls the electric motor according to the control commands. The duty ratio indicating the combination is set such that even if the duty ratio is falsely recognized, a false recognition concerning the actuator operation direction is prevented, such false recognition causing the valve phase to change in an undesirable direction, and even if the actuator operation direction is falsely recognized, the rate of change in the phase is restricted.

In an intake valve phase control after an engine stop command is issued, a stop-time phase is used as a target value. In the intake valve phase control, when the mode changeover condition is not satisfied, and an electric motor that serves as an actuator is not in a locked-state, the highest-speed mode, in which the amount of electric power supplied to the electric motor is fixed to the maximum value, is selected to reliably change the intake valve phase by a required amount. Then, the intake valve phase comes close to the stop-time phase and the mode changeover condition is satisfied, the control mode is changed from the highest-speed mode to the normal mode to set the control phase to the stop-time phase with higher accuracy, and the feedback control over the intake valve phase is executed.

Variable valve timing system and method for controlling the same

At the time of reference position learning, an operation amount of an actuator is set such that intake valve phase changes to a position of most retarded angle in a region where the amount of change in intake valve phase relative to the actuator operation amount is small (S). When the intake valve phase reaches the position of most retarded angle and the change in the intake valve phase stops (YES at S), it is determined that the intake valve phase has reached the position of most retarded angle as the reference phase, and learning is completed. Further, in response to completion of learning, power supply to the electric motor as the actuator is stopped. Consequently, it becomes possible to reduce power consumption and to protect the apparatus at the reference position learning for ensuring accuracy in detecting valve opening/closing timing.

An actuator operation amount setting unit prepares the rotational speed command value for an electric motor such that the phase of an intake valve changes in accordance with the target phase. An electric-motor EDU controls the motor supply electric power such that the electric motor operates in accordance with the rotational speed command value. An overheating determination unit determines whether at least one of the electric motor and the electric-motor EDU needs to be restricted from heating up based on a result of comparison between the information indicating the motor supply electric power and the reference value. A rotational speed command value restriction unit restricts the rotational speed command value provided to the electric-motor EDU to a value within a predetermined range, when it is determined that the at least one of the electric motor and the electric-motor EDU needs to be restricted from heating up. A reference value setting unit variably sets the reference value based on the rotational speed of the electric motor.

In a variable valve timing apparatus in which a phase of an intake valve is changed at an amount of change according to a rotational speed of relative rotation between an electric motor as an actuator and a camshaft, the set upper limit value of the rotational speed of relative rotation and a coefficient N&#x3b8; of conversion from a required phase-change amount to the rotational speed of relative rotation &#x394;Nm in each control period are set at smaller values at the time of engine stop than at the time of engine operation. As a result, the rotational speed of the electric motor in the VVT operation at the time of engine stop is reduced thereby reducing the operation sound of the variable valve timing apparatus.

Variable valve timing apparatus with reduced operation sound and control method thereof

An intake valve phase setting unit sets the target valve phase used in the variable valve timing control based on the engine operating state, and a control target value setting unit sets the control target value based on the target valve phase. An actuator operation amount setting unit prepares the rotational speed command value for an electric motor that serves as an actuator of a variable valve timing system based on the deviation of the current value from the control target value. A phase change rate control unit sets the rate of change in the valve phase to a lower value when the variable valve timing control moves the valve phase away from the reference phase (the phase when the engine is idling) at which combustion takes place stably in engine than when the variable valve timing control causes the valve phase to the reference phase.

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Toyota, Japan

Yasumichi Inoue