JP2004176609A - Engine valve timing controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine valve timing controller capable of improving the exhaust gas characteristics of an engine, and realizing combustion stability even in the cold state of the engine. <P>SOLUTION: An engine valve timing controller has an exhaust valve and a suction valve for opening and closing an exhaust port and a suction port of a combustion chamber partitioned with a piston, a valve timing change means for changing at least either of a closing timing of the exhaust valve or a closing timing of the suction valve, and a catalyst provided in an exhaust passage communicating with the exhaust port. The controller is constituted so that it is provided with a cold state time opening and closing timing setting means (S105) for setting a valve timing when the exhaust valve closes at an exhaust top dead point of the piston at cold state of the engine, and a non-cold timing opening and closing timing control means (S107) for changing the exhaust valve closing timing into a suction stroke of the piston by the valve timing change means, changing the suction valve opening timing into the exhaust stroke of the piston or changing at least one of them at a non-cold timing of the engine. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a valve timing control device for an engine, and more particularly, to a valve timing control device for an engine that improves exhaust gas characteristics from a cold state to a non-cooled state of the engine.
[0002]
[Prior art]
Generally, since the valve timing of the intake valve and the exhaust valve has a great effect on the output performance of the engine, the valve timing of at least one of the intake valve and the exhaust valve is changed in accordance with the engine speed. There is a variable valve timing technology that sets an optimal valve timing corresponding to the number of revolutions to improve the engine output.
[0003]
The variable valve timing technique is used to open the intake valve before the top dead center of the piston and close the exhaust valve after the top dead center of the piston. Technology that improves the suction efficiency by using the negative pressure in the cylinder generated when exhaust gas is discharged by changing the valve closing timing of the valve and setting a valve overlap region where both the intake valve and the exhaust valve open. (For example, see Patent Document 1).
[0004]
Further, when the valve overlap region is provided, the internal EGR increases, so that the combustion of the engine becomes slow, the combustion temperature is reduced, and the generation of NOx can be suppressed.
[0005]
[Patent Document 1]
JP 2001-5040 A (paragraph number 0030, FIG. 2, etc.)
[0006]
[Problems to be solved by the invention]
However, since the internal EGR increases when the valve overlap region is provided, it may be difficult to secure combustion stability, particularly when the engine is cold, where fuel vaporization characteristics are low.
The present invention has been made in view of such a problem, and provides an engine valve timing control device capable of improving exhaust gas characteristics of an engine and achieving combustion stability even in a cold state of the engine. The purpose is to do.
[0007]
[Means for Solving the Problems]
To achieve the above object, a valve timing control device for an engine according to the present invention according to claim 1 includes an exhaust valve and an intake valve that respectively open and close an exhaust port and an intake port of a combustion chamber defined by a piston; A valve timing control apparatus for an engine, comprising: valve timing changing means for changing at least one of a closing timing of an exhaust valve and an opening timing of the intake valve; and a catalyst provided in an exhaust passage communicating with the exhaust port. In the cold state of the engine, at the top dead center of the exhaust of the piston, the exhaust valve is closed, and during the intake stroke of the piston, the open / close timing setting means for setting the valve timing to open the intake valve; and In a non-cold state, the valve timing changing means changes the exhaust valve closing timing to the intake stroke of the piston, or It is characterized in that a non-cold-opening and closing timing control means for performing at least one of the changes or to change the opening timing in the exhaust stroke of the piston.
[0008]
Therefore, the engine valve timing control device according to the first aspect of the present invention can reduce the internal EGR when the engine is cold to ensure combustion stability, while the exhaust valve and the engine are not cooled when the engine is not cold. By providing an overlap region in which the intake valve and the intake valve are both opened, the internal EGR is increased, the combustion temperature is reduced, and the generation of NOx can be suppressed.
[0009]
According to the second aspect of the present invention, an exhaust valve and an intake valve that open and close an exhaust port and an intake port of a combustion chamber defined by a piston, respectively, and the closing timing of the exhaust valve or the opening timing of the intake valve. Shift information detecting means for detecting shift information of a transmission in an engine valve timing control device having valve timing changing means for changing at least one of the following, and a catalyst provided in an exhaust passage communicating with the exhaust port. When the engine is cold and a non-traveling range is detected by the shift information detecting means, the exhaust valve closes at an exhaust top dead center of the piston, and the intake valve is closed during an intake stroke of the piston. A cold opening / closing timing setting means for setting a cold valve timing when the valve opens, and the cold valve timing setting means for setting the cold valve timing. After setting the valve timing, when switching from the non-traveling range to the traveling range is detected by the shift information detecting means, the valve timing changing means changes the exhaust valve closing timing to the intake stroke of the piston, or Non-cold opening / closing timing control means for changing the intake valve opening timing to the exhaust stroke of the piston or at least one of the changes is provided.
[0010]
Therefore, the engine valve timing control device according to the second aspect of the present invention, when detecting that the shift of the transmission is switched from the non-traveling range to the traveling range, increases the output thereafter and raises the engine temperature. The valve timing can be changed at the optimum timing by predicting that the valve timing will be increased and increasing the internal EGR in advance.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows a schematic configuration diagram of an internal combustion engine mounted on a vehicle. Hereinafter, a configuration of a valve timing control device for an internal combustion engine according to the present invention will be described.
The internal combustion engine (hereinafter referred to as the engine) 1 has a fuel injection mode of, for example, fuel injection during a piston intake stroke (intake stroke injection mode), fuel injection during a compression stroke (compression stroke injection mode), and fuel injection during an exhaust stroke. (Exhaust stroke injection mode), an in-cylinder injection type spark ignition type 4-cycle 4-cylinder gasoline engine which can be switched to an (exhaust stroke injection mode) is employed. The in-cylinder injection type engine 1 operates in the stoichiometric air-fuel ratio (stoichio) and in the rich air-fuel ratio (rich air-fuel ratio operation) and also in the lean air-fuel ratio by switching the fuel injection mode and controlling the air-fuel ratio. Operation at a fuel ratio (lean air-fuel ratio operation) is feasible.
[0012]
As shown in the figure, an electromagnetic injector 6 is attached to a cylinder head 2 of the engine 1 together with a spark plug 4 for each cylinder. The injector 6 is provided in a combustion chamber 5 defined by a piston 21. Fuel can be injected directly.
An ignition coil 8 that outputs a high voltage is connected to the ignition plug 4. Further, a fuel supply device (not shown) having a fuel tank is connected to the injector 6 via a fuel pipe 7. More specifically, the fuel supply device is provided with a low-pressure fuel pump and a high-pressure fuel pump, whereby fuel in the fuel tank is supplied to the injector 6 at a low fuel pressure or a high fuel pressure, and the fuel is supplied to the injector 6. The fuel can be injected into the combustion chamber 5 at a predetermined fuel pressure.
[0013]
An intake port 9 is formed in the cylinder head 2 in a substantially upright direction for each cylinder. An intake port 9 a communicating the intake port 9 and the combustion chamber 5 is provided on the combustion chamber 5 side of each intake port 9. An intake valve 11 for opening and closing is provided. The intake valve 11 opens and closes an intake port 9a following a cam 12a of a camshaft 12 that rotates according to engine rotation. One end of an intake manifold 10 is connected to each intake port 9.
[0014]
The intake manifold 10 is provided with an electromagnetic throttle valve 17 for adjusting the amount of intake air. In the vicinity of the throttle valve 17, a throttle position sensor (TPS) 18 for detecting a throttle opening is provided, and the TPS 18 is provided with an idle switch (idle SW). Further, a Karman vortex airflow sensor 19 is provided at a portion of the intake manifold 10 upstream of the throttle valve 17 to detect the amount of intake air.
[0015]
An exhaust port 13 is formed in the cylinder head 2 in a substantially horizontal direction for each cylinder, and an exhaust port for communicating the exhaust port 13 with the combustion chamber 5 is provided on the combustion chamber 5 side of each exhaust port 13. An exhaust valve 15 for opening and closing the port 13a is provided. The exhaust valve 15 opens and closes an exhaust port 13a following a cam 16a of a camshaft 16 that rotates according to engine rotation. One end of an exhaust manifold 14 is connected to each exhaust port 13.
[0016]
An exhaust pipe 20 is connected to the other end of the exhaust manifold 14, and a three-way catalytic converter 30 capable of purifying HC, CO, and NOx with high efficiency in the vicinity of stoichio is interposed in the exhaust pipe 20. Further, an O ₂ sensor 22 for detecting the oxygen concentration in the exhaust gas and thus the exhaust air-fuel ratio is provided immediately upstream of the three-way catalytic converter 30 in the exhaust pipe 20. A high temperature sensor 32 for detecting is provided.
[0017]
Further, the cylinder head 2 is provided with a variable valve timing mechanism 40 that varies the opening / closing timing of the intake valve 11 and the exhaust valve 15 by advancing or retarding the cam 12a or the cam 16a by adjusting the hydraulic pressure. As the variable valve timing mechanism 40, for example, a pendulum type variable valve timing mechanism that swings the camshafts 12 and 16 is applied. It should be noted that a pendulum type variable valve timing mechanism is known, and the detailed description of the configuration is omitted here.
[0018]
The ECU 60 includes an input / output device, a storage device, a central processing unit (CPU), a timer counter, and the like. The ECU 60 controls the engine 1 comprehensively.
The input side of the ECU 60, the TPS18, air flow sensor 19, _{O 2} sensor 22, other such high temperature sensor 32, coolant temperature sensor 62 for detecting the cooling water temperature Tw of the engine 1, Ya crank angle sensor 64 for detecting a crank angle And various sensors such as a shift sensor (shift information detecting means) 66 for detecting shift information of a transmission (not shown) for transmitting the output of the engine 1 to the wheels, and detecting information from these sensors. Is entered. The engine speed Ne is detected from the crank angle sensor 64.
[0019]
On the other hand, on the output side of the ECU 60, various output devices such as the injector 6, the ignition coil 8, the throttle valve 17, the variable valve timing mechanism 40, and the like are connected. Each signal of a fuel injection amount, a fuel injection timing, an ignition timing, and a throttle opening based on a fuel injection mode selected based on the various detection information and a combustion air-fuel ratio obtained according to the detection information from various sensors. Are respectively output.
[0020]
As a result, an appropriate amount of fuel is injected from the injector 6 at an appropriate timing, spark ignition is performed at an appropriate timing by the ignition plug 4, the throttle opening is controlled to an appropriate opening, and furthermore, the throttle opening is changed. An appropriate valve timing command is issued to the valve timing mechanism 40.
In particular, in the present invention, the ECU 60 is provided with the valve timing control device 61 according to the present invention. When the engine is cold started, the intake air is closed to close the combustion chamber 5 based on the output signal from the valve timing control device 61. The valve 11 and the exhaust valve 15 are both closed, while only the intake valve 11 is opened to open the combustion chamber 5 immediately after the top dead center (exhaust top dead center) TDC of the piston 21 in the exhaust stroke. Then, at the time of first idling thereafter, the exhaust valve 15 is closed at the exhaust top dead center TDC by the valve timing control device 61, and the intake valve 11 is opened in the intake stroke of the piston after the exhaust top dead center TDC. . Further, when the engine is not cold after the control at the time of the first idling, the closing timing is changed by the valve timing control device 61 so as to close the exhaust valve 15 in the piston intake stroke after the exhaust top dead center TDC. Note that the exhaust top dead center TDC refers to the position where the piston 21 comes closest to the cylinder head 2 during the exhaust stroke of the piston 21.
[0021]
Hereinafter, the operation of the thus-configured valve timing control device for the engine 1 according to the present invention will be described.
FIG. 2 shows the control at the time of cold start and the control at the time of the first idling (the control at the time of cold) performed by the opening / closing timing changing means at the time of cold of the valve timing control device 61 according to the present invention. A control routine of start control (non-cold control) by the non-cold opening / closing timing changing means is shown in a flowchart, and will be described below with reference to the flowchart.
[0022]
When the start switch is turned on in step S101, the cold start control by the valve timing control device 61 is performed in step S102 and step S103.
Specifically, in step S102, the timing is changed so that the opening timing IO of the intake valve 11 is set to the exhaust top dead center TDC which is the most retarded side, and in step S103, the closing timing EC of the exhaust valve 15 is advanced most. The timing is changed so that it is before the exhaust top dead center TDC on the corner side. That is, by changing the opening timing IO of the intake valve 11 and the closing timing EC of the exhaust valve 15, a negative overlap VOLn is set to close the combustion chamber 5, and the process proceeds to step S104.
[0023]
In step S103, the fuel injection timing of the injector 6 is changed to the timing when the intake valve 11 and the exhaust valve 15 are closed, in other words, to the end stage of the exhaust stroke, in accordance with the output signal of the valve timing control device 61. To step S104.
In step S104, it is determined whether or not the engine rotation fluctuation is equal to or more than a predetermined value. If it is determined that the fluctuation is equal to or more than the predetermined value, that is, if YES, the process proceeds to step S105, and the cold start control is terminated. The control at the time of first idling is performed by the opening / closing timing changing means during cold state.
[0024]
Specifically, in step S105, a timing change to the retard side to set the closing timing EC of the exhaust valve 15 to the exhaust top dead center TDC is performed by feedback control, and the process proceeds to step S106. Further, the fuel injection timing of the injector 6 is changed to the early stage of the intake stroke after the closing timing EC of the exhaust valve 15. On the other hand, if it is determined in step S104 that the difference is not equal to or larger than the predetermined value, the process returns to step S102 to continue the cold start control.
[0025]
In step S106, it is determined whether the output signal of the shift sensor 66 has been switched from the neutral range N (non-traveling range) to the drive range D (traveling range), and it is determined that the output has been switched from the N range to the D range. If the answer is YES, that is, if YES, the process proceeds to step S107, where the control at the time of first idling by the opening / closing timing changing means in the cold state is ended, and the starting control by the opening / closing timing changing means at the cold state is performed.
[0026]
Specifically, in step S107, the timing of closing the exhaust valve 15 to the piston intake stroke after the exhaust top dead center TDC is changed to the retard side by feedback control, and the process proceeds to step S108. Further, the fuel injection timing of the injector 6 is changed to the middle stage of the intake stroke after the closing timing EC of the exhaust valve 15. On the other hand, if it is determined in step S106 that the range has not been switched from the N range to the D range, the process returns to step S105 to continue the first idle control.
[0027]
In step S108, it is determined whether or not the engine rotation fluctuation is equal to or more than a predetermined value. If the fluctuation is equal to or more than the predetermined value, that is, if YES, the process proceeds to step S109, and the closing timing EC of the exhaust valve 15 is shifted to the advance side. The timing is changed by the feedback control, and the opening timing IO of the intake valve 11 is changed by the feedback control to a timing before the exhaust top dead center TDC which is on the advance side, so that the overlap around the exhaust top dead center TDC is performed. The area is set and a series of control is completed. In this case, the injector 6 performs normal compression or intake stroke injection control. If it is determined in step S108 that the value is not equal to or larger than the predetermined value, the process returns to step S107 to continue the start-time control.
[0028]
Here, in the cold start control according to the present embodiment, the cold start control is switched to the first idling control in step S104 according to the engine rotation fluctuation. Alternatively, the switching may be performed when the catalyst temperature is equal to or higher than a predetermined temperature, when the engine rotation speed is equal to or higher than the predetermined rotation speed, or when the shift information of the transmission is switched from the P range to the N range. .
[0029]
In the first idle control according to the present embodiment, the process is terminated when the shift range is switched from the N range to the D range in step S106. However, as another example, the control is stopped for a predetermined time after the first idle control is performed. May be terminated when the engine water temperature becomes equal to or higher than a predetermined value or when the catalyst temperature becomes equal to or higher than a predetermined value.
[0030]
As in the present embodiment, when the shift information of the transmission is switched from the non-traveling range P range or N range to the traveling range D range, the control is switched from the fast idle control to the non-cold control. With this configuration, it is possible to predict that the engine output will increase and the engine temperature will increase in the future, and to set the valve overlap region, which is the control at the time of non-cold state, in advance to increase the internal EGR. Can be more appropriately suppressed.
[0031]
That is, even if there is a time lag between the time when the valve timing change command is output from the ECU 60 to the variable valve timing mechanism 40 and the time when the valve timing is actually changed, the ECU 60 is switched to the D range which is the traveling range. By issuing a command to change the valve timing to the variable valve timing mechanism 40, when the occupant depresses the accelerator pedal and the engine speed actually increases, the valve timing is not changed and the combustion temperature increases. Accordingly, the situation where NOx increases can be suppressed.
[0032]
FIG. 3 is a timing chart of the cold start control (steps S102 and S103). This control at the cold start is performed until the engine rotation fluctuation exceeds a predetermined value. In the figure, the vertical axis indicates the valve lift Lf, the horizontal axis indicates the crank angle θ, EO and EC indicate the opening timing and closing timing of the exhaust valve 15, respectively, and IO and IC indicate the opening timing of the intake valve 11. The timing and the closing timing are shown.
[0033]
At the time of cold start of the engine, the opening timing IO of the intake valve 11 is set to a position immediately after the exhaust top dead center TDC, and the closing timing EC of the exhaust valve 15 is set to a position before the exhaust top dead center TDC. The negative overlap VOLn is set between the opening timing IO of the intake valve 11 and the closing timing EC of the exhaust valve 15, and the combustion chamber 5 is sealed. The fuel injection is performed at the end of the exhaust stroke of the negative overlap VOLn from immediately after the closing timing EC of the exhaust valve 15 to the exhaust top dead center TDC.
[0034]
As described above, when the engine is started cold, the closing timing EC of the exhaust valve 15 is set before the exhaust top dead center TDC, and the opening timing IO of the intake valve 11 is set at the exhaust top dead center TDC. Once the air is blown out of the combustion chamber 5 from the intake port 9a, the piston 21 returns to the combustion chamber 5 satisfactorily again due to a sufficient negative pressure due to the lowering of the piston 21, and the combustion chamber 5 is sealed and the residual gas is compressed. By performing the fuel injection while the fuel gas is being injected, the temperature of the mixture of the fuel and the residual gas trapped in the combustion chamber 5 rises with an increase in the in-cylinder pressure, and the mixture of the fuel with the air and the mist of the fuel Is promoted.
[0035]
FIG. 4 is a timing chart of the first idling control (step S105) by the cold opening / closing timing changing means of the valve timing control device 61. The control at the time of the first idling is performed until the range is switched from the N range to the D range.
As shown in the figure, at the time of first idling, the opening timing IO of the intake valve 11 remains immediately after the exhaust top dead center TDC, while the closing timing EC of the exhaust valve 15 is located at the exhaust top dead center TDC. The change to the retard side is performed as described above, and the negative overlap VOLn is eliminated. That is, the closing timing EC of the exhaust valve 15 coincides with the opening timing IO of the intake valve 11, and both the valve overlap VOLp and the negative overlap VOLn become substantially zero. The fuel injection is performed at an early stage of the intake stroke at the exhaust top dead center TDC.
[0036]
As described above, at the end of the cold start control, the cold opening / closing timing changing means adjusts the opening / closing timing of the intake valve 11 and the exhaust valve 15 so that the overlap becomes substantially equal to zero. Thus, the internal EGR amount can be reduced, and combustion stability can be ensured even if the fuel vaporization characteristics are lowered due to a low engine temperature.
[0037]
In the first idle control, even if the opening timing IO of the intake valve 11 is set during the piston intake stroke after the exhaust top dead center TDC of the piston, the same operation and effect as the above embodiment can be achieved.
FIG. 5 is a timing chart of the start-up control after the first idle time by the non-cold opening / closing timing changing means (step S107) of the valve timing control device 61. This start-time control is performed until the engine rotation fluctuation exceeds a predetermined value.
[0038]
As shown in the figure, at the time of start, although the opening timing IO of the intake valve 11 is located immediately after the exhaust top dead center TDC, the closing timing EC of the exhaust valve 15 is behind the exhaust top dead center TDC. A change to the retard side is performed so as to be located in a certain piston intake stroke, and a valve overlap region VOLp is formed. The fuel injection is performed in the middle stage of the intake stroke immediately after the closing timing EC of the exhaust valve 15.
[0039]
As described above, since the non-cold open / close timing changing means adjusts the open / close timing of the exhaust valve 15 so as to form a valve overlap, the internal EGR amount is increased from the end of the first idle control. And the generation of NOx can be effectively suppressed.
As described above, according to the present invention, in the cold state, which is the first idling time, the opening / closing timing changing means in the cold state of the valve timing control device 61 controls the opening / closing timing of the intake valve 11 and the exhaust valve 15 so as not to form the valve overlap. Can be changed to reduce the internal EGR amount to ensure combustion stability, and to switch to the D range and change the opening / closing timing in the non-cold state of the valve timing control device 61 in the non-cold state intended to start. Since the means changes the valve closing timing of the exhaust valve 15 so as to form a valve overlap to increase the internal EGR amount and suppress the generation of NOx, the exhaust gas from the start of the engine 1 to the start of the engine 1 is reduced. Characteristics can be optimized.
[0040]
The description of one embodiment of the present invention is finished above, but the present invention is not limited to the above embodiment, and various changes can be made without departing from the spirit of the present invention.
For example, in the above embodiment, the in-cylinder injection type engine is described, but the valve timing control device can be applied to, for example, a multi-point injection (MPI) type engine in addition to the engine 1. In addition, it is possible to achieve appropriate exhaust gas characteristics from start to start.
[0041]
In the above embodiment, when the engine is started cold, the closing timing EC of the exhaust valve 15 is set before the exhaust top dead center TDC, and the opening timing IO of the intake valve 11 is set as the exhaust top dead center TDC. However, the present invention is not limited to this, and the closing timing EC of the exhaust valve 15 is set to the exhaust top dead center TDC during the cold start of the engine, as in the case of the fast idle control. The opening / closing timing control in the cold state in which the opening timing IO of the intake valve 11 is set to the intake stroke of the piston 21 after the exhaust top dead center TDC may be performed.
[0042]
In the above embodiment, when the engine is not cold, the exhaust valve 15 is closed during the piston intake stroke after the exhaust top dead center TDC. However, the present invention is not limited to this mode. Open the piston exhaust stroke before the exhaust top dead center TDC, or simultaneously change the closing timing EC of the exhaust valve 15 to the piston intake stroke and change the opening timing IO of the intake valve 11 to the piston exhaust stroke. A positive overlap may be formed, and in this case, the internal EGR amount can be increased.
[0043]
【The invention's effect】
As can be understood from the above description, according to the engine valve timing control apparatus of the present invention, when the engine is cold, the exhaust valve is set at the exhaust top dead center of the piston by the cold opening / closing timing setting means. Since the valve timing is set such that the intake valve is opened during the intake stroke of the piston by closing the valve, the internal EGR can be reduced to ensure combustion stability. By changing the valve closing timing to the intake stroke of the piston or changing the valve opening timing of the intake valve to the exhaust stroke of the piston to provide an overlap region where both the exhaust valve and the intake valve are opened, It is possible to increase the EGR to lower the combustion temperature and suppress the generation of NOx.
[0044]
According to the second aspect of the present invention, when it is detected that the shift of the transmission has been switched from the non-traveling range to the traveling range, it is predicted that the output will increase and the engine temperature will rise thereafter. By increasing the internal EGR, the valve timing can be changed at an optimal timing.
[Brief description of the drawings]
FIG. 1 is an engine system configuration diagram according to an embodiment of the present invention.
2 is a control at the time of cold start, a control at the time of first idling (control at the time of cold) by the opening / closing timing changing means of the cold state of the valve timing control device of FIG. It is a flowchart of a control routine of (non-cold state control).
FIG. 3 is a timing chart of cold start control.
FIG. 4 is a timing chart of control at the time of first idling by a switching unit for changing the opening / closing timing in a cold state.
FIG. 5 is a timing chart of starting control by a non-cold opening / closing timing changing unit.
[Explanation of symbols]
1 engine 5 combustion chamber 9a intake port 11 intake valve 13 exhaust passage 13a exhaust port 15 exhaust valve 21 piston 30 catalyst 60 ECU (electronic control unit)
61 Valve timing control device 66 Shift sensor

Claims (2)

An exhaust valve and an intake valve that respectively open and close an exhaust port and an intake port of a combustion chamber partitioned by a piston,
Valve timing changing means for changing at least one of the closing timing of the exhaust valve or the opening timing of the intake valve,
A valve timing control device for an engine having a catalyst provided in an exhaust passage communicating with the exhaust port,
When the engine is cold, the exhaust valve is closed at the top dead center of the exhaust of the piston, and a cold opening / closing timing setting means for setting the valve timing of opening the intake valve in the intake stroke of the piston;
When the engine is not cold, at least one of changing the valve closing timing of the exhaust valve to the intake stroke of the piston, or changing the valve opening timing of the intake valve to the exhaust stroke of the piston by the valve timing changing means. And a non-cold opening / closing timing control means. An exhaust valve and an intake valve that respectively open and close an exhaust port and an intake port of a combustion chamber partitioned by a piston,
Valve timing changing means for changing at least one of the closing timing of the exhaust valve or the opening timing of the intake valve,
A valve timing control device for an engine having a catalyst provided in an exhaust passage communicating with the exhaust port,
Having shift information detecting means for detecting shift information of the transmission,
When the engine is cold and the non-traveling range is detected by the shift information detecting means, the exhaust valve closes at the top dead center of the exhaust of the piston, and the intake valve opens during the intake stroke of the piston. Opening / closing timing setting means for setting the cold valve timing,
After the setting of the cold valve timing by the cold valve timing setting means, when the shift information detecting means detects the switching from the non-traveling range to the traveling range, the valve timing changing means detects the exhaust valve closing timing. A non-cold opening / closing timing control means for performing at least one of: changing the piston stroke to the intake stroke of the piston, or changing the opening timing of the intake valve to the exhaust stroke of the piston. Valve timing control device.

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