JP2010077850A - Phase determining device for valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To determine accurately that the valve phase is changed to the target phase. <P>SOLUTION: The ECU of a phase determining device controls the phase of an intake valve so that it changes into the target phase, calculates the smoothed value evtbsm of the phase of the intake valve obtained by smoothing the phase using a predetermined time constant, determines whether the phase of the intake valve is changed to the target value by comparing the update amount edlvtbsm with the threshold for determination, edlvtbsm being based on the value obtained by subtracting the smoothed value evtbsm from the actual phase, and alters the threshold for determination in accordance with the engine temperature. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a valve phase determination device, and more particularly to a technique for determining whether or not the phase of a valve whose phase is changed by a variable valve timing mechanism provided in an engine has changed to a target phase.

  Conventionally, VVT (Variable Valve Timing) is known in which a phase (crank angle) at which an intake valve or an exhaust valve opens and closes is changed according to an operating state. In general, in VVT, the phase is changed by rotating a camshaft for opening and closing an intake valve and an exhaust valve relative to a sprocket or the like.

  In VVT that is widely used, the camshaft is rotated by hydraulic pressure. Further, a VVT in which a camshaft is rotated by an actuator such as an electric motor has been put into practical use. In VVT in which the camshaft is rotated by an electric motor, the phase of the valve can be detected from the operation amount (cumulative rotation speed) of the electric motor.

  However, if the phase of the camshaft is detected from the operating amount of the electric motor, the phase detected from the operating amount of the electric motor may be different from the actual phase due to the influence of some disturbance. Therefore, for example, by periodically changing the phase of the valve to the slowest phase that is mechanically determined and learning the operation amount of the electric motor at this time, the error between the detected phase and the actual phase is corrected. It is necessary.

Japanese Patent Application Laid-Open No. 2007-270754 (Patent Document 1) generates an actuator operation instruction so as to change the opening / closing timing to a predetermined timing, executes a learning operation, and responds to the opening / closing timing reaching the predetermined timing. Then, a variable valve timing device that learns the reference timing of the rotation timing is disclosed. In the variable valve timing device described in this publication, it is detected that the opening / closing timing has reached a predetermined timing when the amount of change in the opening / closing timing becomes substantially zero.
JP 2007-270754 A

  However, for example, when the operating speed of the VVT becomes slow in a state where the engine temperature (cooling water temperature) is low, even if the phase change is not completed, the phase change amount can be substantially zero. Therefore, if it is determined that the phase of the valve has reached the target phase when the amount of phase change becomes substantially zero, even if the phase change has not been completed, the phase is set to the target level when the engine temperature is low. It may be erroneously determined that the phase has changed.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a valve phase determination device that can accurately determine that the phase of the valve has changed to a target phase. That is.

  A valve phase determination device according to a first aspect of the present invention is a valve phase determination device whose phase is changed by a variable valve timing mechanism provided in an engine. This phase determination device uses means for controlling the valve phase to change to the target phase and a threshold value to determine whether or not the valve phase has changed to the target phase. Judgment means and changing means for changing the threshold value according to the engine temperature are provided.

  According to this configuration, the threshold value used for determining whether or not the phase of the valve has changed to the target phase is changed according to the engine temperature. Thus, it is possible to determine whether or not the valve phase has changed to the target phase by using an optimum threshold value corresponding to the operating speed of the variable valve timing mechanism. For example, when the engine temperature is low, the threshold value is changed so as to determine that the valve phase has changed to the target phase when the amount of phase change is smaller than when the engine temperature is high. That is, when the operating speed of the variable valve timing mechanism is slow, the threshold value is changed so that it is determined that the valve phase has changed to the target phase when the amount of phase change is smaller than when the variable valve timing mechanism is fast. The Therefore, when the phase change is not completed, it can be difficult to erroneously determine that the phase has changed to the target phase. As a result, it is possible to provide a valve phase determination device that can accurately determine that the phase of the valve has changed to the target phase.

  The valve phase determination apparatus according to the second invention further includes a calculation means for calculating a smooth value obtained by smoothing the phase of the valve, in addition to the configuration of the first invention. The determination means includes means for determining that the phase of the valve has changed to the target phase when the difference between the valve phase and the smooth value is smaller than the threshold value.

  According to this configuration, it is determined whether or not the valve phase has changed to the target phase using a smoothed value obtained by smoothing the valve phase. The smooth value changes with a delay with respect to the actual phase. Therefore, when the actual phase change amount is large, the difference between the actual phase and the smooth value becomes large. On the other hand, when the actual phase change amount is small, the difference between the actual phase and the smooth value is small. Therefore, if the difference between the actual phase and the smooth value is small, it can be said that the smooth value has caught up with the phase, that is, the actual phase has reached the target phase. Therefore, if the difference between the valve phase and the smoothed value obtained by smoothing the valve phase is smaller than the threshold value, it is determined that the valve phase has changed to the target phase. Thereby, it can be accurately determined whether or not the phase of the valve has changed to the target phase.

  In the valve phase determination apparatus according to the third aspect of the invention, in addition to the configuration of the second aspect of the invention, the calculation means calculates a first smoothed value obtained by smoothing the phase of the valve with the first time constant. And means for calculating a second smoothed value obtained by smoothing the phase of the valve with a second time constant smaller than the first time constant. The determination means includes means for determining that the valve phase has changed to the target phase when the difference between the valve phase and the first smoothing value is smaller than the threshold value, and the valve phase and the second smoothing value. If the difference between the values is less than the threshold value earlier than the difference between the valve phase and the first smooth value, then if the difference between the valve phase and the second smooth value is less than the threshold value, Means for determining that the phase has changed to the target phase.

  According to this configuration, if the difference between the valve phase and the first smooth value is smaller than the threshold value, it is determined that the valve phase has changed to the target phase. However, when the valve phase changes quickly, even if the valve phase reaches the target phase, it takes a long time until the difference between the valve phase and the first smooth value becomes smaller than the threshold value. May be needed. Therefore, it is determined whether or not the phase of the valve has changed to the target phase using a second smoothed value obtained by smoothing the phase of the valve with a second time constant smaller than the first time constant. . That is, it is determined whether or not the phase of the valve has changed to the target phase by using the second smooth value having a smaller delay from the actual phase than the first smooth value. If the difference between the valve phase and the second smooth value is smaller than the threshold value earlier than the difference between the valve phase and the first smooth value, there is a difference between the valve phase and the second smooth value. If it is smaller than the threshold value, it is determined that the valve phase has changed to the target phase. Thus, it can be quickly determined that the phase of the valve has changed to the target phase.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

<First Embodiment>
With reference to FIG. 1, the engine of the vehicle carrying the phase determination apparatus based on the 1st Embodiment of this invention is demonstrated.

  The engine 1000 is a V-type 8-cylinder engine in which “A” bank 1010 and “B” bank 1012 are each provided with a group of four cylinders. An engine of a type other than the V type 8 cylinder may be used.

  Engine 1000 receives air from air cleaner 1020. The intake air amount is adjusted by a throttle valve 1030. The throttle valve 1030 is an electronic throttle valve that is driven by a motor.

  Air is introduced into the cylinder 1040 through the intake passage 1032. Air is mixed with fuel in a cylinder 1040 (combustion chamber). Fuel is directly injected from the injector 1050 into the cylinder 1040. That is, the injection hole of the injector 1050 is provided in the cylinder 1040.

  Fuel is injected during the intake stroke. Note that the timing of fuel injection is not limited to the intake stroke. In this embodiment, engine 1000 will be described as a direct injection engine in which an injection hole of injector 1050 is provided in cylinder 1040. In addition to direct injection injector 1050, a port injection injector is provided. May be. Further, only a port injection injector may be provided.

  The air-fuel mixture in the cylinder 1040 is ignited by the spark plug 1060 and burned. The air-fuel mixture after combustion, that is, the exhaust gas is purified by the three-way catalyst 1070 and then discharged outside the vehicle. The piston 1080 is pushed down by the combustion of the air-fuel mixture, and the crankshaft 1090 rotates.

  An intake valve 1100 and an exhaust valve 1110 are provided at the top of the cylinder 1040. Intake valve 1100 is driven by intake camshaft 1120. The exhaust valve 1110 is driven by an exhaust camshaft 1130. Intake camshaft 1120 and exhaust camshaft 1130 are connected by a chain, gear, or the like, and rotate at the same rotational speed.

  The phase (opening / closing timing) of intake valve 1100 is controlled by intake VVT mechanism 2000 provided on intake camshaft 1120.

  In the present embodiment, intake camshaft 1120 is rotated by intake VVT mechanism 2000, whereby the phase of intake valve 1100 is controlled. Further, the phase of intake valve 1100 can change within a mechanically limited range in accordance with the structure of intake VVT mechanism 2000. The method for controlling the phase is not limited to this. In addition to the intake valve 1100, the phase (opening / closing timing) of the exhaust valve 1110 may be changed.

  Intake VVT mechanism 2000 is operated by electric motor 2040 (not shown in FIG. 1). The electric motor 2040 is controlled by the ECU 4000. The current and voltage of the electric motor 2040 are detected by an ammeter (not shown) and a voltmeter (not shown) and input to the ECU 4000.

  Engine 1000 is provided with cylinder deactivation mechanism 3000 in addition to intake VVT mechanism 2000. The cylinder deactivation mechanism 3000 suspends the vertical movement of the intake valve 1100 and the exhaust valve 1110, for example, by making the rocker arm free with respect to the cam so that the rocker arm does not move following the cam.

  By stopping the vertical movement of the intake valve 1100 and the exhaust valve 1110, a cylinder deactivation operation is performed in which intake and exhaust are suspended in some cylinders of the plurality of cylinders. For example, among the eight cylinders, intake and exhaust are suspended only in the cylinders of “B” bank 1012. Note that the cylinders that stop intake and exhaust are not limited to these.

  When the vertical movement of intake valve 1100 and exhaust valve 1110 is stopped, fuel injection from injector 1050 and ignition by spark plug 1060 are stopped.

  In addition, since it is sufficient to use a well-known technique for the cylinder deactivation operation, further detailed description will not be repeated here.

  ECU 4000 receives signals representing the rotational speed of crankshaft 1090 (engine rotational speed NE) and the crank angle from crank angle sensor 5000. ECU 4000 also receives a signal representing the phases of intake camshaft 1120 and exhaust camshaft 1130 (the position of the camshaft in the rotational direction) from cam position sensor 5010.

  Further, the ECU 4000 receives from the water temperature sensor 5020 a signal indicating the water temperature (cooling water temperature) of the engine 1000 and receives from the air flow meter 5030 a signal indicating the intake air amount of the engine 1000 (the amount of air sucked into the engine 1000). Is done.

  Based on signals input from these sensors, a map stored in a memory (not shown), and a program, ECU 4000 controls throttle opening, ignition timing, fuel injection so that engine 1000 can be in a desired operating state. The timing, fuel injection amount, intake valve 1100 phase, exhaust valve 1110 phase, and the like are controlled.

  In the present embodiment, ECU 4000 determines the phase of intake valve 1100 based on a map using engine speed NE and load KL as parameters, as shown in FIG. A plurality of maps for determining the phase of the intake valve 1100 are stored for each water temperature.

  Hereinafter, the intake VVT mechanism 2000 will be further described. As shown in FIG. 3, intake VVT mechanism 2000 includes sprocket 2010, plate 2020, reduction gear 2030, and electric motor 2040.

  The sprocket 2010 is connected to the crankshaft 1090 via a chain or the like. The number of revolutions of the sprocket 2010 is one half of the number of revolutions of the crankshaft 1090. An intake camshaft 1120 is provided so as to be concentric with the rotation axis of the sprocket 2010 and to be rotatable relative to the sprocket 2010.

  The plate 2020 is connected to the intake camshaft 1120 by pins 2050. The plate 2020 rotates integrally with the intake camshaft 1120 inside the sprocket 2010. Note that the plate 2020 and the intake camshaft 1120 may be integrally formed.

  When the plate 2020 rotates relative to the sprocket 2010, the intake camshaft 1120 rotates relative to the sprocket 2010, and the phase of the intake valve 1100 is changed.

  The plate 2020 is provided with a plurality of recesses 2022 for connecting the plate 2020 and the speed reducer 2030 on the surface on the speed reducer 2030 side.

  The reduction gear 2030 includes an external gear 2032 and an internal gear 2034. The external gear 2032 is fixed to the sprocket 2010 so as to rotate integrally with the sprocket 2010.

  The internal gear 2034 is formed with a plurality of convex portions 2036 that are received in the concave portions 2022 of the plate 2020. The internal gear 2034 is supported rotatably about an eccentric shaft 2046 of a coupling 2042 formed eccentrically with respect to the shaft center 2044 of the output shaft of the electric motor 2040.

  The AA cross section in FIG. 3 is shown in FIG. The internal gear 2034 is provided such that some of the plurality of teeth mesh with the external gear 2032. When the output shaft rotation speed of the electric motor 2040 is the same as the rotation speed of the sprocket 2010, the coupling 2042 and the internal gear 2034 rotate at the same rotation speed as the external gear 2032 (sprocket 2010). In this case, the plate 2020 rotates at the same rotational speed as the sprocket 2010, and the phase of the intake valve 1100 is maintained.

  When the coupling 2042 is rotated relative to the external gear 2032 around the axis 2044 by the electric motor 2040, the entire internal gear 2034 rotates (revolves) around the axis 2044, The internal gear 2034 rotates around the eccentric shaft 2046. Due to the rotational movement of the internal gear 2034, the plate 2020 is rotated relative to the sprocket 2010, and the phase of the intake valve 1100 is changed.

  The phase of intake valve 1100 changes when the relative rotational speed between the output shaft of electric motor 2040 and sprocket 2010 (the amount of operation of electric motor 2040) is reduced by reduction gear 2030. The phase of intake valve 1100 may be changed by increasing the relative rotational speed between the output shaft of electric motor 2040 and sprocket 2010.

  The sprocket 2010 is provided with a stopper that limits the movable range of the plate 2020. The phase of intake valve 1100 can vary within a range that is mechanically limited by the stopper.

  The function of ECU 4000 will be described with reference to FIG. Note that the functions described below may be realized by software or hardware.

  ECU 4000 includes a control unit 4002, a calculation unit 4004, a determination unit 4006, and a change unit 4008.

  The control unit 4002 performs control so that the phase of the intake valve 1100 changes to the target phase. More specifically, when starting engine 1000, control unit 4002 controls intake valve 1100 so that the phase of intake valve 1100 changes to the slowest phase (most retarded angle phase) that is mechanically limited.

  The calculation unit 4004 calculates a smoothed value evtbsm obtained by smoothing the phase of the intake valve 1100 with a predetermined time constant. The smooth value evtbsm is calculated according to the following equation 1. In Equation 1, evtbsm (i) indicates the current value of the smoothed value evtbsm. evtbsm (i-1) indicates the previous value of the smooth value evtbsm. evt indicates the actual phase of the intake valve 1100.

evtbsm (i) = evtbsm (i-1) + (evt-evtbsm (i-1)) / time constant ... (1)
As is apparent from Equation 1, the smooth value evtbsm is calculated by repeatedly updating with the update amount edlvtbsm represented by “(evt−evtbsm (i−1)) / time constant”. That is, the smooth value evtbsm is calculated by repeatedly updating with the update amount edlvtbsm based on the difference between the actual phase of the intake valve 1100 and the smooth value evtbsm. Further, when retarding the phase of the intake valve 1100, “evt-evtbsm (i−1)” becomes a negative value. Equation 1 is an example, and the method of calculating the smooth value evtbsm is not limited to this.

  As illustrated in FIG. 6, the determination unit 4006 determines that the phase of the intake valve 1100 has changed to the target phase when the update amount edlvtbsm of the smooth value evtbsm is greater than the determination threshold. In the present embodiment, it is determined that the phase of intake valve 1100 has changed to the most retarded phase. Also, a value less than or equal to zero is set as the determination value threshold value.

  Here, the update amount edlvtbsm of the smooth value evtbsm is calculated by dividing the difference between the actual phase of the intake valve 1100 and the smooth value evtbsm by the time constant. Further, when retarding the phase of the intake valve 1100, “evt-evtbsm (i−1)” becomes a negative value. Further, the difference between the actual phase of intake valve 1100 and the smoothed value evtbsm means the absolute value of the value obtained by subtracting smoothed value evtbsm from the actual phase of intake valve 1100. Further, the determination value threshold is a value of zero or less.

  Accordingly, the fact that the update amount edlvtbsm of the smooth value evtbsm is larger than the determination threshold value means that the difference between the actual phase of the intake valve 1100 and the smooth value evtbsm is the threshold value (the product of the determination threshold value and the time constant). Is smaller than the absolute value).

  That is, when the difference between the actual phase of intake valve 1100 and the smoothed value evtbsm is smaller than the threshold value, determination unit 4006 determines that the phase of intake valve 1100 has changed to the target phase.

  Changing unit 4008 changes the threshold value to be compared with the difference between the actual phase of intake valve 1100 and smooth value evtbsm in accordance with the temperature of engine 1000.

  More specifically, the changing unit 4008 changes the determination threshold value to be compared with the updated amount edlvtbsm of the smooth value evtbsm according to the water temperature of the engine 1000.

  For example, when the water temperature of engine 1000 is low, the determination threshold is set so that the phase of intake valve 1100 has changed to the target phase when the amount of phase change is smaller than when the water temperature is high. Be changed. As shown in FIG. 7, when the water temperature of engine 1000 is low, the determination threshold is increased (the absolute value of the determination threshold is decreased) compared to when the water temperature is high.

  Therefore, the threshold value to be compared with the difference between the actual phase of the intake valve 1100 and the smooth value evtbsm is reduced by increasing the determination threshold value compared with the update amount edlvtbsm of the smooth value evtbsm. That is, when the water temperature of engine 1000 is low, the threshold value compared with the difference between the actual phase of intake valve 1100 and smooth value evtbsm is made smaller than when the water temperature is high. Note that the threshold correction method is not limited to this.

A control structure of a program executed by ECU 4000 will be described with reference to FIG. In addition,
In step (hereinafter, step is abbreviated as S) 100, ECU 4000 performs control so that the phase of intake valve 1100 changes to the most retarded phase.

  In S102, ECU 4000 calculates a smoothed value evtbsm obtained by smoothing the phase of intake valve 1100. In S104, ECU 4000 changes (sets) a determination threshold value to be compared with update amount edlvtbsm of smooth value evtbsm according to the water temperature of engine 1000.

  In S106, ECU 4000 determines whether or not update amount edlvtbsm of smooth value evtbsm is larger than the determination threshold value, that is, whether or not the difference between actual phase of intake valve 1100 and smooth value evtbsm is smaller than the threshold value. Determine. If update amount edlvtbsm of smooth value evtbsm is larger than the determination threshold value (YES in S106), the process proceeds to S108. If not (NO in S106), the process returns to S100.

  In S108, ECU 4000 determines that the phase of intake valve 1100 has changed to the most retarded phase.

  A process performed by ECU 4000 based on the above-described structure and flowchart will be described.

  For example, when engine 1000 is started, in order to learn the most retarded phase of intake valve 1100, control is performed so that the phase of intake valve 1100 changes to the most retarded phase (S100).

  In order to determine whether or not the phase of the intake valve 1100 has changed to the most retarded phase, a smoothed value evtbsm obtained by smoothing the phase of the intake valve 1100 is calculated (S102).

  The smooth value evtbsm changes with a delay from the actual phase. Further, the update amount edlvtbsm of the smooth value evtbsm is calculated by subtracting the smooth value evtbsm from the actual phase. When the phase is retarded, the update amount edlvtbsm becomes a negative value.

  Therefore, when the actual phase change amount is large, the update amount edlvtbsm is small (the difference between the actual phase and the smooth value evtbsm is large). Conversely, when the actual phase change amount is small, the update amount edlvtbsm increases (the difference between the actual phase and the smooth value evtbsm decreases).

  Therefore, when the update amount edlvtbsm is large (the difference between the actual phase and the smooth value evtbsm is small), the smooth value evtbsm has caught up with the phase, that is, the actual phase has reached the most retarded phase. It can be said.

  Therefore, if update amount edlvtbsm of smooth value evtbsm is larger than the determination threshold value (YES in S106), that is, if the difference between the actual phase of intake valve 1100 and smooth value evtbsm is smaller than the threshold value, It is determined that the phase of intake valve 1100 has changed to the most retarded phase (S108).

  However, when the water temperature of engine 1000 is low, that is, when the temperature of the lubricating oil of engine 1000 is low, the operating speed of intake VVT mechanism can be slow. In this case, as shown in FIG. 9, even if the phase does not change to the most retarded phase, the difference between the actual phase of the intake valve 1100 and the smooth value evtbsm becomes small, and the update amount edlvtbsm of the smooth value evtbsm becomes It can be greater than the decision threshold. In this case, even if the phase does not change to the most retarded phase, it can be erroneously determined that the phase has changed to the most retarded phase.

  Therefore, the determination threshold value to be compared with the update amount edlvtbsm of the smooth value evtbsm is changed according to the water temperature of the engine 1000 (S104). For example, the determination threshold value is increased when the water temperature of engine 1000 is low compared to when the water temperature is high. Thereby, it is possible to determine whether or not the phase of intake valve 1100 has changed to the target phase using an optimal determination threshold value corresponding to the operating speed of intake VVT mechanism 2000. Therefore, when the phase has not changed to the most retarded phase, it can be difficult to erroneously determine that the phase has changed to the most retarded phase. As a result, it can be accurately determined that the phase of the intake valve 1100 has changed to the target most retarded phase.

<Second Embodiment>
Hereinafter, a second embodiment will be described. In the present embodiment, two smoothed values evtbsm having different time constants are calculated, and when any one of the two smoothed values evtbsm is larger than the determination threshold, the phase is the most retarded phase. It differs from the first embodiment described above in that it is determined that it has changed. Other structures are the same as those in the first embodiment. Therefore, detailed description thereof will not be repeated here.

  Referring to FIG. 10, calculation unit 4014 of ECU 4000 in the present embodiment has first smoothed value evtbsm1 obtained by smoothing the phase of intake valve 1100 with a first time constant, and the phase of intake valve 1100 as a first time constant. The second smoothed value evtbsm2 smoothed with a smaller second time constant is calculated.

  The first smoothed value evtbsm1 and the second smoothed value evtbsm2 are calculated according to the following formulas 2 and 3 similar to the formula 1, respectively.

evtbsm1 (i) = evtbsm1 (i-1) + (evt-evtbsm1 (i-1)) / first time constant (2)
evtbsm2 (i) = evtbsm2 (i-1) + (evt-evtbsm2 (i-1)) / second time constant (3)
As shown in FIG. 11, the determination unit 4016 normally has the update amount edlvtbsm1 of the first smooth value evtbsm1 having a large time constant larger than the determination threshold, that is, the phase of the intake valve 1100 and the first smooth value evtbsm1. Is smaller than the threshold value, it is determined that the valve phase has changed to the most retarded phase.

  On the other hand, when the update amount edlvtbsm2 of the second smooth value evtbsm2 having a small time constant becomes larger than the determination threshold earlier than the update amount edlvtbsm1 of the first smooth value evtbsm1, the update amount edlvtbsm2 of the second smooth value evtbsm2 is determined. When it becomes larger than the threshold value, it is determined that the phase of the valve has changed to the most retarded phase.

  That is, when the difference between the phase of the intake valve 1100 and the second smoothed value evtbsm2 is smaller than the threshold earlier than the difference between the phase of the intake valve 1100 and the first smoothed value evtbsm1, the phase of the intake valve 1100 and the second If the difference from the smooth value evtbsm2 is smaller than the threshold value, it is determined that the phase of intake valve 1100 has changed to the most retarded phase.

  As shown in FIG. 12, when the actual phase change amount is large, the update amount edlvtbsm2 of the second smoothed value evtbsm2 is smaller than the speed determination threshold value set as a value smaller than the determination threshold value. Then, it is determined that the difference between the phase of the intake valve 1100 and the second smoothed value evtbsm2 is smaller than the threshold earlier than the difference between the phase of the intake valve 1100 and the first smoothed value evtbsm1.

  Therefore, if there is a history that the update amount edlvtbsm2 of the second smooth value evtbsm2 smaller than the speed determination threshold value has been calculated, the phase of the valve is increased when the update amount edlvtbsm2 of the second smooth value evtbsm2 is greater than the determination threshold value. Is determined to have changed to the most retarded phase.

  With reference to FIG. 13, a control structure of a program executed by ECU 4000 in the present embodiment will be described. Note that the same step numbers are assigned to the same processes as those in the first embodiment. Therefore, detailed description thereof will not be repeated here.

  In S200, ECU 4000 smoothes the first smoothed value evtbsm1 obtained by smoothing the phase of intake valve 1100 with a first time constant, and the second smoothed value obtained by smoothing the phase of intake valve 1100 with a second time constant smaller than the first time constant. 2 Calculate the smooth value evtbsm2.

  In S202, ECU 4000 determines whether or not there is a history in which update amount delvtbsm2 of second smoothed value evtbsm2 smaller than the speed determination threshold is calculated. If there is a history in which update amount delvtbsm2 smaller than the speed determination threshold is calculated (YES in S202), the process proceeds to S204. If not (NO in S204), the process proceeds to S206.

  In S204, ECU 4000 determines whether or not update amount edlvtbsm2 of second smooth value evtbsm2 is larger than the determination threshold value, that is, the difference between actual phase of intake valve 1100 and second smooth value evtbsm2 is a threshold value. It is judged whether it is smaller than. If update amount edlvtbsm2 of second smooth value evtbsm2 is larger than the determination threshold value (YES in S204), the process proceeds to S108. If not (NO in S204), the process returns to S100.

  In S206, ECU 4000 determines whether or not update amount edlvtbsm1 of first smooth value evtbsm1 is larger than the determination threshold value, that is, the difference between actual phase of intake valve 1100 and first smooth value evtbsm1 is a threshold value. It is judged whether it is smaller than. If update amount edlvtbsm1 of first smooth value evtbsm1 is larger than the determination threshold value (YES in S206), the process proceeds to S108. If not (NO in S206), the process returns to S100.

  A process performed by ECU 4000 based on the above-described structure and flowchart will be described.

  When control is performed so that the phase of intake valve 1100 changes to the most retarded phase (S100), the first smoothed value evtbsm1 obtained by smoothing the phase of intake valve 1100 with the first time constant, and the phase of intake valve 1100 are set. A second smoothed value evtbsm2 smoothed with a second time constant smaller than the first time constant is calculated (S200).

  Normally, when update amount edlvtbsm1 of first smoothing value evtbsm1 having a large time constant is larger than the determination threshold value (YES in S206), it is determined that the phase of intake valve 1100 has changed to the most retarded phase. (S108).

  However, as shown in FIG. 14, when the operating speed of intake VVT mechanism 2000 is fast, that is, when the amount of phase change is large, the actual phase and first smoothed value evtbsm1 are caused by the large time constant. The difference can be large. In this case, even after the phase has changed to the most retarded angle phase, the update amount edlvtbsm1 of the first smooth value evtbsm1 can be larger for a longer time than the determination threshold. Therefore, it may take a long time to determine that the phase has changed to the most retarded phase even though the phase has changed to the most retarded phase.

  Therefore, if the difference between the phase of the intake valve 1100 and the second smoothed value evtbsm2 is smaller than the threshold value earlier than the difference between the phase of the intake valve 1100 and the first smoothed value evtbsm1, the phase of the intake valve 1100 and the second If the difference from smooth value evtbsm2 is smaller than the threshold value (YES in S204), it is determined that the phase of intake valve 1100 has changed to the most retarded phase (S108).

  More specifically, when the difference between the phase of the intake valve 1100 and the second smoothed value evtbsm2 is smaller than the threshold earlier than the difference between the phase of the intake valve 1100 and the first smoothed value evtbsm1, Since the amount of change is large, it is used that the update amount edlvtbsm2 obtained by subtracting the second smoothed value evtbsm2 from the actual phase is small.

  If there is a history in which the update amount edlvtbsm2 of the second smooth value evtbsm2 smaller than the speed determination threshold is calculated (YES in S202), the phase is the most retarded according to the update amount edlvtbsm2 of the second smooth value evtbsm2. It is determined whether or not the phase has changed.

  If update amount edlvtbsm2 of second smooth value evtbsm2 is larger than the determination threshold value (YES in S204), it is determined that the phase of intake valve 1100 has changed to the most retarded phase (S108). Thereby, it can be quickly determined that the phase of intake valve 1100 has changed to the most retarded phase.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a schematic block diagram which shows an engine. It is a figure which shows the map which defined the phase of the intake camshaft. It is sectional drawing which shows the VVT mechanism for intake. It is AA sectional drawing of FIG. It is a functional block diagram of ECU in a 1st embodiment. It is a figure which shows the smooth value evtbsm and update amount edlvtbsm. It is a figure which shows a determination threshold value. It is a flowchart which shows the control structure of the program which ECU runs in 1st Embodiment. It is a figure which shows the smooth value evtbsm and the update amount edlvtbsm in a state with low engine water temperature. It is a functional block diagram of ECU in 2nd Embodiment. It is a figure which shows the 1st smooth value evtbsm1 and update amount edlvtbsm1. It is a figure which shows the 2nd smooth value evtbsm2 and update amount edlvtbsm2. It is a figure which shows the control structure of the program which ECU runs in 2nd Embodiment. It is a figure which shows the 1st smooth value evtbsm1, the update amount edlvtbsm1, the 2nd smooth value, and the update amount edlvtbsm2 when the operating speed of the intake VVT mechanism 2000 is fast.

Explanation of symbols

  1000 engine, 1010 “A” bank, 1012 “B” bank, 1020 air cleaner, 1030 throttle valve, 1040 cylinder, 1050 injector, 1060 spark plug, 1070 three-way catalyst, 1090 crankshaft, 1100 intake valve, 1110 exhaust valve, 1120 Intake camshaft, 1130 exhaust camshaft, 2000 VVT mechanism for intake, 2010 sprocket, 2020 plate, 2010 sprocket, 2020 plate, 2022 concave portion, 2030 reduction gear, 2032 external gear, 2034 internal gear, 2036 convex portion, 2040 Electric Motor, 2042 coupling, 2044 shaft center, 2046 eccentric shaft, 2050 pin, 3000 cylinder idle Mechanism, 4000 ECU, 4002 control unit, 4004,4014 calculator, 4006,4016 determination unit, 4008 changing unit, 5000 a crank angle sensor, 5010 cam position sensor, 5020 water temperature sensor, 5030 air flow meter.

Claims (3)

A valve phase determination device whose phase is changed by a variable valve timing mechanism provided in an engine,
Means for controlling the phase of the valve to change to a target phase;
Determination means for determining whether or not the phase of the valve has changed to a target phase using a threshold;
A valve phase determination device comprising: changing means for changing the threshold value according to the temperature of the engine. A calculation means for calculating a smoothed value obtained by smoothing the phase of the valve;
The said determination means includes a means for determining that the phase of the valve has changed to a target phase when the difference between the phase of the valve and the smooth value is smaller than a threshold value. Valve phase determination device. The calculating means includes
Means for calculating a first smoothed value obtained by smoothing the phase of the valve with a first time constant;
Means for calculating a second smoothed value obtained by smoothing the phase of the valve with a second time constant smaller than the first time constant;
The determination means includes
Means for determining that the phase of the valve has changed to a target phase if the difference between the phase of the valve and the first smooth value is less than the threshold;
If the difference between the valve phase and the second smooth value is less than the threshold earlier than the difference between the valve phase and the first smooth value, the valve phase and the second smooth value The valve phase determination device according to claim 2, further comprising means for determining that the phase of the valve has changed to a target phase when a difference from a smooth value is smaller than the threshold value.

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