Toyota Jidosha Kabushiki Kaisha

Toyota Jidosha Kogyo Kabushiki Kaisha

Nobuhisa Ohkawa

Senji Kato

Tadahisa Naganawa

Kouji Endou

Atsushi Yasumura

Shigeru Sone

Nobuyuki Kobayashi

Hiroshi Ito

Toshiaki Isobe

Tadashi Saito

Atsushi Gotou

Atsushi Goto

Yoshihito Moriya

Yoshiya Yamashita

Hitoshi Uda

Yuji Yoshihara

Takahide Kuma

Kouji Endo

Sone Shigeru

In detecting the occurrence of an abnormality in a variable valve timing mechanism, which continuously changes a valve timing by advancing or delaying the displacement angle of an intake-side cam shaft with respect to a crankshaft, an abnormality detecting apparatus for a valve timing control apparatus determines that the variable valve timing mechanism is failing when the absolute value of the difference between a target displacement angle and a correct real displacement angle, obtained by subtracting the maximum delay-angle learning value from the real displacement angle, is greater than a first predetermined value and the absolute value of the difference between a correct real displacement angle and a previous correct real displacement angle is equal to or smaller than a second predetermined value.

Abnormality detecting apparatus for internal combustion engine

A valve timing control apparatus that continuously controls the valve timing of an intake valve or an exhaust valve of an engine. This apparatus includes a hydraulic variable valve timing mechanism, a hydraulic control valve and an electronic control unit for controlling the control valve. The variable valve timing mechanism alters the valve timing to change the valve overlap of the intake valve with respect to the exhaust valve. The hydraulic control valve controls the hydraulic pressure supplied to the variable valve timing mechanism. The real phase of the valve timing is coincided with a target phase that corresponds with the running conditions of the engine. When the real phase of the valve timing approaches the target phase, the hydraulic control valve is controlled to sustain the phase of that instant. The electronic control unit, which learns the control state of the valve-timing sustaining control, sets an initial learning value that reduces the valve overlap when the learning has started. A correction means is disallowed from computing a current specific value when the computed target value is within a predetermined range.

Valve timing control apparatus with a disallowing means

A valve timing control apparatus that continuously controls the valve timing of an intake valve or an exhaust valve of an engine. This apparatus includes a hydraulic variable valve timing mechanism, a hydraulic control valve and an electronic control unit for controlling the control valve. The variable valve timing mechanism alters the valve timing to change the valve overlap of the intake valve with respect to the exhaust valve. The hydraulic control valve controls the hydraulic pressure supplied to the variable valve timing mechanism. The real phase of the valve timing is coincided with a target phase that corresponds with the running conditions of the engine. When the real phase of the valve timing approaches the target phase, the hydraulic control valve is controlled to sustain the phase of that instant. The electronic control unit, which learns the control state of the valve-timing sustaining control, sets an initial learning value that reduces the valve overlap when the learning has started. A restricting means for restricting a correction means is included.

Valve timing control apparatus with a restricting means

A valve timing control apparatus that continuously controls the valve timing of an intake valve or an exhaust valve of an engine. This apparatus includes a hydraulic variable valve timing mechanism, a hydraulic control valve and an electronic control unit for controlling the control valve. The variable valve timing mechanism alters the valve timing to change the valve overlap of the intake valve with respect to the exhaust valve. The hydraulic control valve controls the hydraulic pressure supplied to the variable valve timing mechanism. The real phase of the valve timing is coincided with a target phase that corresponds with the running conditions of the engine. When the real phase of the valve timing approaches the target phase, the hydraulic control valve is controlled to sustain the phase of that instant. The electronic control unit, which learns the control state of the valve-timing sustaining control, sets an initial learning value that reduces the valve overlap when the learning has started. An initializing means is added for initializing a current specific value when a recondition after a malfunction is determined.

Valve timing control apparatus with an initializing means

An improvement of a valve timing control apparatus for an engine is disclosed. The apparatus has an intake valve and an exhaust valve which are alternately opened and closed in a valve timing sequence according to a rotation of a cam shaft. A timing pulley mounted on the cam shaft has a housing accommodating a plunger movable therein and a sleeve secured to the cam shaft. The housing has a first and second pressure chambers defined by the plunger and sealed with respect to each other. The plunger is arranged to move in an axial direction to selectively advance and retard the cam shaft based on differential pressure between the first pressure chamber and the second pressure chamber. A controller controls an electromagnetic valve with a specific control value to adjust the fluid pressure to be supplied to the first and second pressure chambers to maintain the valve timing sequence converged to a target valve timing. The controller corrects the specific value based on a rotational speed of the engine when the plunger is in one of the extreme positions in the chambers, and adjusts the fluid pressures based on the corrected specific value.

Valve timing control apparatus for engine

A valve timing control apparatus that adjusts valve overlap by altering valve timing according to the running condition of the engine. A variable valve timing mechanism (VVT) alters the valve timing of intake valves to adjust the valve overlap. An electronic control unit (ECU) controls the VVT with respect to a target value calculated in accordance to the running condition of the engine to obtain the optimum valve overlap. The ECU controls the VVT to eliminate valve overlap under low temperature conditions. The ECU controls the VVT to switch from a state of nonexistent valve overlap to a valve overlap state as the temperature changes from a low temperature to a higher temperature. The ECU judges whether the engine is in a low temperature condition based on a predetermined reference value to suppress the difference in the amount of fuel (port wet amount) adhered to the intake port before and after the shifting of the state the valve overlap.

A valve timing control apparatus that continuously controls the valve timing of an intake valve or an exhaust valve of an engine. This apparatus includes a hydraulic variable valve timing mechanism, a hydraulic control valve and an electronic control unit for controlling the control valve. The variable valve timing mechanism alters the valve timing to change the valve overlap of the intake valve with respect to the exhaust valve. The hydraulic control valve controls the hydraulic pressure supplied to the variable valve timing mechanism. The real phase of the valve timing is coincided with a target phase that corresponds with the running conditions of the engine. When the real phase of the valve timing approaches the target phase, the hydraulic control valve is controlled to sustain the phase of that instant. The electronic control unit, which learns the control state of the valve-timing sustaining control, sets an initial learning value that reduces the valve overlap when the learning has started.

Disclosed is a device for calculating an amount of an air introduced to a cylinder of an engine. An air-intake passage introduces the air to the cylinder. An air-exhaust passage exhausts gas from the cylinder. Both passages respectively have an intake valve and an exhaust valve. Both valves are respectively driven by an intake valve drive mechanism and an exhaust valve drive mechanism in accordance with a rotation of a crank shaft to alternatively and selectively open and close, and simultaneously open during a valve overlap period to open the passages to the cylinder. A variable valve timing mechanism controls an operational timing of the valve drive mechanisms with respect to the crank shaft in accordance with a running condition of the engine to vary a timing of the valve driven by the valve drive mechanisms. The calculating device comprises a first detecting device, which detects a rotational speed of the crank shaft. A second detecting device detects an intake pressure in the air-intake passage. A third detecting device detects the operational timing of the valve drive mechanisms. A calculating device calculates a displacement of the operational timing according to the detected rotational speed of the crank shaft and the detected operational timing. A first computing device computes the amount of the air introduced to the cylinder in response to the rotational speed of the crank shaft, the intake pressure, and the displacement of the operational timing.

Apparatus for computing the amount of intake air in internal combustion

A cam shaft of an engine is provided with a timing change mechanism (VVT) which is driven by hydraulic pressure to alter the timing of a intake valve (valve timing). This VVT is controlled to change the valve overlap of the intake valve and an exhaust valve, thereby adjusting the suction and exhaust in and from a combustion chamber. To control the VVT, an electronic control unit (ECU) computes a target value for the valve timing in accordance with the running condition of the engine and controls the supply of the hydraulic pressure to the VVT based on the target value. The ECU determines the level of the actual hydraulic pressure given to the VVT. When the actual valve timing does not lie in a predetermined range with respect to the target value, the ECU determines that an abnormality has occurred in the VVT, and executes a predetermined fail safe routine. When the hydraulic pressure is equal to or smaller than a reference value, the ECU suppresses VVT malfunction determinations.

A cam shaft of an engine is provided with a timing change mechanism (VVT) which is driven by hydraulic pressure to alter the timing of a intake valve (valve timing). This VVT is controlled to change the valve overlap of the intake valve and an exhaust valve, thereby adjusting the suction and exhaust in and from a combustion chamber. To control the VVT, an electronic control unit (ECU) computes a target value for the valve timing in accordance with the running condition of the engine and controls the supply of the hydraulic pressure to the VVT based on the target value. The ECU determines the level of the actual hydraulic pressure given to the VVT. When the actual valve timing does not lie in a predetermined range with respect to the target value, the ECU determines that an abnormality has occurred in the VVT, and executes a predetermined fail safe routine. When the hydraulic pressure is equal to or smaller than a reference value, the ECU suppresses WT malfunction determinations.

A varying mechanism (VVT) for continuously varying the valve timing of an intake valve in a predetermined range is provided on a cam shaft in an engine. By controlling the VVT, the valve overlap period of the intake valve and an exhaust valve is continuously varied in a predetermined range, thus adjusting the amount of the internal EGR in combustion chambers. When determining that the operational load of the engine is small and intermediate based on the value of a manifold pressure, an electronic control unit (ECU) computes a target value for advancing the valve timing with respect to the rotational phase of a crankshaft based on a throttle angle, an engine speed, etc. The ECU also computes a limit value to restrict the target value in accordance with the value of the manifold pressure. When the target value is smaller than the limit value, the ECU controls the VVT based on the target value. When the target value is greater than the limit value, the ECU replaces the limit value with target value and controls the VVT based on this target value.

This system computes final fuel injection amount TAU on the basis of the following formula;

Learning control system of air-fuel ratio in electronic control engine

An intake air flow rate control device comprises a bypass passage for bypassing a throttle valve arranged in an intake manifold, flow control valve arranged in the bypass passage and stepping motor for driving the flow control valve. When the throttle valve is substantially fully closed, the stepping motor is driven to control an opening area of the flow control valve so that an engine rotational speed is within a range of a target rotational speed for at least an engine coolant temperature. In the above-described control, a lower limit of a stepping position of the stepping motor is set to prevent the opening area from being reduced beyond a predetermined area in order to prevent engine stall.

Engine idling rotational speed control device

Intake air flow rate control means having a control valve and a stepping motor for driving the control valve is arranged in a passage other than a passage in which a throttle valve is disposed. In a fast idling control mode (when a coolant temperature is below 70.degree. C., for example) and a hot idling control mode (when the coolant temperature is above 70.degree. C., for example), the control valve is driven by the stepping motor to control an engine idling rotational speed. The numbers of steps of the stepping motor for given coolant temperatures, which are to be used in the fast idling control mode, are previously stored as tables ST1.about.ST3. A converted value ISTA of steps corresponding to a target rotational speed is calculated based on a predetermined conversion expression. An arithmetic operation is carried out such that the number of steps ISTEP, which was learnt in the previous hot idling control mode and stored in a permanently powered memory, is equal to the converted value ISTA. In the fast idling control mode, prior to the feedback control of the control valve, the number of steps of the stepping motor ST for the given coolant temperature is corrected based on the number of steps ISTEP stored in the memory. The stepping motor is controlled by the corrected number of steps ST1A.about.ST3A.

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Toyota, Japan

Nobuhisa Ohkawa