JP2001271663A - Internal combustion engine with electromagnetically driven valve train - Google Patents

Abstract

(57) Abstract: An internal combustion engine provided with an electromagnetically driven valve capable of suppressing the temperature of a lean NOx catalyst and other catalysts using the electromagnetically driven valve. An engine intake / exhaust valve (28, 29) is utilized by using electromagnetic force.
And electromagnetically driven valve mechanisms 30A and 31A having electromagnetic drive mechanisms 30 and 31 for opening and closing, and an exhaust pipe 47 of an engine having a plurality of cylinders 21 for purifying exhaust gas discharged from the cylinders 21 and flowing to the exhaust pipe 47. When the temperature of the exhaust gas purifying catalyst and the temperature of the exhaust gas purifying catalyst are higher than the predetermined required temperature T1, at least the electromagnetic drive mechanism 31 related to the exhaust valve 29 of the intake / exhaust valves 28 and 29 is operated to activate the exhaust valve 29. The ECU 20 is provided as an exhaust gas temperature lowering means for correcting the valve timing and / or the head to lower the temperature of the exhaust gas exiting from the cylinder 21 to lower the temperature of the exhaust purification catalyst to a predetermined required temperature T1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve mechanism for an internal combustion engine mounted on an automobile or the like, and more particularly, to open / close an inlet valve as an intake valve and an exhaust valve as an exhaust valve using electromagnetic force. The present invention relates to an internal combustion engine having an electromagnetically driven valve train.

[0002]

2. Description of the Related Art In recent years, in an internal combustion engine mounted on an automobile or the like, an electromagnetically driven valve mechanism (hereinafter referred to as an electromagnetically driven valve mechanism) that opens and closes an inlet valve or an exhaust valve using an electromagnetic drive mechanism that uses electromagnetic force. "Valve") is being developed.

An electromagnetically driven valve is made of a magnetic material, and has an armature as a movable piece that moves forward and backward in conjunction with an inlet valve or an exhaust valve, and an inlet valve or an exhaust valve that attracts the armature when an exciting current is applied. An electromagnet for closing the valve, an electromagnet for opening the inlet valve and the exhaust valve when the exciting current is applied to open the inlet valve or the exhaust valve, a valve-closing side return spring for urging the armature in the valve closing direction, and an armature. And a valve-opening-side return spring that urges the valve in the valve-opening direction at least in its constituent members.
No. 67005).

[0004] In such an electromagnetically driven valve, an appropriate space (hereinafter referred to as "space portion") is provided between the valve closing electromagnet and the valve opening electromagnet.
The two magnets are arranged in series with a space therebetween, and the armature is arranged in the space. When no exciting current is applied to the electromagnetically driven valve, the armature is held at an intermediate position of the space in a neutral state in which the spring force of the valve-side return spring and the spring force of the valve-side return spring are balanced. .

[0005] By applying the exciting current, an electromagnetic force is generated between the valve-closing electromagnet and the valve-opening electromagnet to displace the armature toward the valve-closing electromagnet or the valve-opening electromagnet. Under the influence of the electromagnetic force and the spring force, the armature advances or retreats toward the valve-closing electromagnet or the valve-opening electromagnet, thereby opening and closing an inlet valve and an exhaust valve that are linked to the armature.

If an electromagnetically driven valve is applied to a valve train of an internal combustion engine, an inlet valve and an exhaust valve are utilized by utilizing the rotational force of a crank shaft as in a conventional valve train.
Since there is no need to open and close the valve, mechanical loss is reduced, and the shaft output can be increased accordingly.

Further, according to the electromagnetically driven valve, the inlet valve and the exhaust valve can be opened and closed at an arbitrary timing by correcting the timing of applying the exciting current to the valve-opening electromagnet and the valve-closing electromagnet. It is possible to control the intake air amount of each cylinder without using a throttle valve. As a result, the throttle valve can be prevented from being installed in the intake air pipe, and in that case, the pumping loss can be reduced accordingly.

When such an electromagnetically driven valve is applied to a multi-cylinder engine, the electromagnetically driven valve is provided for each cylinder.

[0009]

On the other hand, in a multi-cylinder engine, the intake air flowing through the intake air pipe toward the cylinder is:
The intake manifold (hereinafter, referred to as “in manifold”), which is an intake branch pipe, is branched into cylinders, and thereafter, the intake air branched into each of the cylinders is a fuel injection device provided corresponding to each cylinder. The fuel is mixed with the engine fuel injected by the injector to form an air-fuel mixture, which is used for engine combustion in the cylinder.

[0010] Thereafter, the exhaust gas discharged from each cylinder is collected by an exhaust manifold (hereinafter referred to as "exhaust manifold"), which is an exhaust collecting pipe, and then flows into the exhaust pipe.

The exhaust pipe is provided with a catalytic converter containing an exhaust gas purifying catalyst (hereinafter referred to as "catalyst"), and the catalytic converter purifies exhaust gas passing through the exhaust pipe.

When the temperature of the catalyst rises and reaches a certain temperature range, the catalyst has a characteristic of purifying harmful components in exhaust gas.
The temperature at which the catalyst is activated so that the purification rate of the exhaust gas by the catalyst becomes 50% or more is referred to as the 50% purification temperature of the catalyst by the oxidation reaction.
Unless otherwise specified, the 50% purification temperature is referred to as “catalyst activation temperature” for convenience.

In addition, for example, Japanese Patent Application Laid-Open No. 5-59936 discloses a technique for controlling the activation temperature of a catalyst by valve timing to speed up the warm-up of the catalyst. Further, the catalyst, by which the air-fuel ratio of the inter alia the exhaust gas absorbs NOx when the lean and releases the air-fuel ratio of the exhaust gas had been absorbed to it when the stoichiometric or rich NOx as NO _2,
The exhaust gas when the occlusion reduction type lean NOx catalyst and the exhaust air-fuel ratio is reduced to N ₂ by the reducing components such as HC and CO in the exhaust gas NO2 is lean and a predetermined reducing agent is present in the exhaust A selective reduction lean NOx catalyst that purifies exhaust gas by reducing contained NOx has a narrower suitable temperature range in which its function can be sufficiently exhibited, for example, than a three-way catalyst.

For this reason, if the temperature of the lean NOx storage reduction catalyst or the lean NOx selective reduction catalyst rises excessively and exceeds the activation temperature of the catalyst, the catalyst will not function effectively due to the heat damage. Therefore, there is a possibility that the NOx storage power of the catalyst is reduced.

For this reason, it is necessary to prevent the catalyst temperature from becoming too high. However, there has not been a technique for suppressing the catalyst temperature from using the electromagnetically driven valve. The present invention has been made in view of the above circumstances, and has as its technical problem to provide an internal combustion engine having an electromagnetically driven valve capable of suppressing the temperature of a catalyst, particularly a lean NOx catalyst, using the electromagnetically driven valve. I do.

[0016]

Accordingly, the present invention employs the following means in order to solve the above-mentioned problems. (1) An internal combustion engine having an electromagnetically driven valve mechanism according to the present invention includes: an electromagnetically driven valve mechanism having an electromagnetically driven mechanism that opens and closes intake and exhaust valves of the internal combustion engine using electromagnetic force; An exhaust purification catalyst provided in an exhaust passage of an internal combustion engine having a plurality of cylinders for purifying exhaust gas discharged from the cylinder and flowing out to the exhaust passage; and a temperature of the exhaust purification catalyst is higher than a predetermined required temperature. When or when it is expected to be high, the electromagnetic drive mechanism of at least the exhaust valve of the intake and exhaust valves is operated, and the valve timing and / or the head of the exhaust valve is corrected to discharge from the cylinder. Exhaust gas temperature lowering means for lowering the temperature of the exhaust gas to be reduced to lower the temperature of the exhaust gas purifying catalyst to the predetermined required temperature.

Here, an ECU that controls the entire internal combustion engine and controls the operation of the electromagnetically driven valve mechanism will be briefly described, and the components of the present invention will be described.

The ECU comprises a central processing unit CPU and a read-only memory RO connected to each other by a bidirectional bus.
M, a random access memory RAM, a backup RAM, an input interface circuit, an output interface circuit, and the like.

The input interface circuit is electrically connected to various sensors mounted on the internal combustion engine or the vehicle. When output signals of these various sensors enter the ECU from the input interface circuit, these parameters are temporarily randomized. It is stored in the access memory RAM.

Then, based on these parameters, C
The PU performs arithmetic processing required by the PU. In executing the arithmetic processing, the CPU performs random processing through the bidirectional bus.
The parameters stored in the access memory RAM are called as needed.

The output interface circuit is electrically connected to the electromagnetic drive mechanism and operates the electromagnetic drive mechanism based on output signals of the various sensors. The operation of the electromagnetic drive mechanism is controlled based on the calculation result of the CPU,
As a result, the intake and exhaust valves are opened and closed.

The "exhaust gas purifying catalyst" can be exemplified by the above-mentioned lean NOx storage reduction catalyst or lean NOx selective reduction catalyst. The “predetermined required temperature” can be exemplified by the activation temperature of the catalyst described in the section of the prior art.

The phrase "when the temperature of the exhaust gas purifying catalyst is higher than or expected to be higher than the predetermined required temperature" means when the temperature is so high that the catalyst cannot effectively exhibit the exhaust gas purifying function.

As a direct means for detecting the temperature of the exhaust purification catalyst, a catalyst temperature sensor which outputs an electric signal corresponding to the bed temperature of the exhaust purification catalyst can be exemplified. As means for estimating, means for estimating the catalyst temperature from the integrated value of the amount of intake air per unit time detected by the air flow meter, for example, stored in the read-only memory ROM, and the vertical axis represents the amount of intake air An example of a catalyst temperature detection map obtained by taking an integrated value and taking time on the horizontal axis can be exemplified.

"Valve timing" refers to when to open and close the intake / exhaust valve relative to the position of the piston reciprocating in the cylinder of the internal combustion engine, in other words, the crankshaft which is the engine output shaft. Absorbs against shaft rotation
It means valve adjustment for opening and closing the exhaust valve.

The opening and closing positions of the intake and exhaust valves are indicated by the rotation angle of the crankshaft (hereinafter referred to as "crank angle") corresponding to the position of the piston. For example, the valve is opened several times after the top dead center or closed several times before the bottom dead center, which indicates the moment when the valve starts to open and the moment when the valve closes.

The term "head" refers to the distance that the intake / exhaust valve separates from the installation position of the valve / seat which comes into contact when the intake / exhaust valve is completely closed, and is also referred to as a valve lift. Depending on the valve timing and head, the amount of intake air and the amount of exhaust gas increase or conversely decrease.

The "exhaust gas temperature lowering means" is used to implement various routines for executing control of the internal combustion engine.
Is one of various application programs stored in the application program. Also, since the attribute of the ROM that stores the program related to the exhaust gas temperature lowering means is in the ECU,
The ECU can be regarded as exhaust gas temperature lowering means.

In the internal combustion engine having the electromagnetically driven valve operating mechanism according to the present invention, when the temperature of the exhaust gas purifying catalyst is higher than a predetermined required temperature, at least the electromagnetic driving mechanism related to the exhaust valve among the intake and exhaust valves is operated. Activate to correct valve timing and / or head of the exhaust valve.

Therefore, depending on the content of this correction,
The temperature of the exhaust gas discharged from the cylinder can be reduced to lower the temperature of the exhaust gas purification catalyst to the predetermined required temperature.

Therefore, in the internal combustion engine having the electromagnetically driven valve operating mechanism according to the present invention, the temperature of the exhaust gas purifying catalyst may be higher than the predetermined required temperature, for example, the activation temperature of the catalyst, depending on the operation state of the internal combustion engine. Even in the case where the exhaust gas temperature is lowered, the exhaust gas temperature lowering means lowers the temperature of the catalyst to the predetermined required temperature, so that the catalyst temperature is prevented from excessively rising, and the exhaust gas purifying function by the catalyst during operation of the engine is effectively exhibited.

(2) In the internal combustion engine having the electromagnetically driven valve operating mechanism according to the present invention, it is determined whether the temperature of the exhaust purification catalyst is high by comparing the temperature of the exhaust purification catalyst with the predetermined required temperature. It is preferable to have a catalyst temperature determination means that performs the determination.

Here, the "catalyst temperature determining means" means the above-mentioned R for realizing various routines for executing control of the internal combustion engine.
This is one of various application programs stored in the OM. Also, since the attribute of the ROM that stores the program related to the catalyst temperature determination means is in the ECU,
The ECU can be referred to as catalyst temperature determination means.

A case where the temperature of the exhaust gas purifying catalyst is higher than the predetermined required temperature is referred to as a high temperature. In the internal combustion engine having the electromagnetically driven valve operating mechanism of the present invention, the temperature of the exhaust gas purifying catalyst is compared with the predetermined required temperature by the catalyst temperature determining means to determine whether or not the internal combustion engine is in a high temperature state. Therefore, it can be reliably determined that the temperature of the exhaust purification catalyst is higher than the predetermined required temperature.

(3) When the catalyst temperature determining means determines that the temperature of the catalyst is higher than the predetermined required temperature, the exhaust gas temperature required to lower the temperature of the catalyst to the predetermined required temperature. It is preferable to have an exhaust gas temperature decrease ratio calculating means for calculating the decrease ratio of the exhaust gas.

Here, "exhaust gas temperature decrease rate calculating means"
Is one of various application programs stored in the ROM for implementing various routines for performing control of the internal combustion engine. Further, since the attribute of the ROM for storing the program relating to the exhaust gas temperature reduction ratio calculating means is in the ECU, the ECU is referred to as the exhaust gas temperature reduction ratio calculating means.

In the internal combustion engine having the electromagnetically actuated valve operating mechanism according to the present invention, the rate of decrease in exhaust gas temperature can be calculated by the exhaust gas temperature decrease rate calculating means, so that the temperature of the catalyst can be accurately reduced to the predetermined required temperature. Can be done.

(4) The exhaust gas temperature lowering means executes the retard control for opening the exhaust valve when the crank angle is in a state after the bottom dead center or executes the retard control when the crank angle is in a state before the top dead center. It is preferable to have a retard control / advance control execution means for executing the advance control for closing the exhaust valve.

The "retard control / advance control execution means" is one of various application programs stored in the ROM for realizing the exhaust gas temperature lowering means. Also, a ROM for storing a program related to an exhaust gas temperature lowering means including a retard control / advance control execution means.
Is attributed to the ECU.
This is referred to as advanced angle control execution means.

Here, generally, the timing of opening and closing the exhaust valve will be described. In an actual engine, the opening and closing of the exhaust valve is not performed when the piston is at the top dead center or the bottom dead center, as is well known, but is performed at a time that is most suitable for engine performance.

A. When to open the exhaust valve The typical time to open the exhaust valve is before the bottom dead center where the explosion process ends. That is, the exhaust valve is opened when the piston is pushed down during the explosion stroke and approaches the vicinity of the bottom dead center.

The reason is that if the exhaust valve is opened after the piston enters the ascending stroke, a large amount of power is lost, and the gas pressure is utilized during the explosion stroke in which the internal pressure of the cylinder still remains. This is because exhausting the exhaust gas enables efficient exhaust gas emission. However, if the exhaust valve is opened in this manner, a part of the explosive work is sacrificed.

B. Timing of closing the exhaust valve The general timing of closing the exhaust valve is after the top dead center at which the exhaust stroke ends.

The reason is that it is necessary to discharge as much residual gas as possible in order to sufficiently perform suction and increase the output of the internal combustion engine. Also, considering the compressibility and inertia of the gas, the exhaust gas can be efficiently discharged by using the gas compressibility and the inertia. Therefore, the exhaust valve is kept open for a certain time after the start of the suction stroke.

In this specification, a diagram showing the opening / closing timing of the exhaust valve as a crank angle is referred to as a valve timing diagram for the exhaust valve. The general opening / closing timing of the exhaust valve indicated by the valve timing diagram of the exhaust valve is referred to as the base opening / closing timing of the exhaust valve for convenience.

"Execution of retard angle control" for the exhaust valve according to the present invention means that the exhaust valve is opened when the opening timing is later than the opening timing of the base opening / closing timing of the exhaust valve and the crank angle is after the bottom dead center. That is.

Similarly, the "execution of the advance angle control" for the exhaust valve means that the exhaust valve is closed earlier than the closing timing at the base opening / closing timing of the exhaust valve and the crank angle is before the top dead center. is there.

In the internal combustion engine having the electromagnetically driven valve operating mechanism according to the present invention, the exhaust valve is opened by executing the above-mentioned retard control.
The opening timing of the exhaust valve is later than the base opening / closing timing. Then, the exhaust gas generated in the cylinder is discharged from the cylinder to the exhaust pipe only after the exhaust temperature has been reduced in the cylinder, so that the temperature of the catalyst provided in the exhaust pipe decreases accordingly.

Further, when the retard control of the exhaust valve is performed, the combustion ratio increases accordingly, which also contributes to the prevention of afterburning in the exhaust pipe. Further, since the exhaust valve is closed by executing the advance angle control, the closing timing of the exhaust valve is earlier than the base opening / closing timing. Then, the period during which the exhaust valve is open is shortened accordingly, so that the amount of exhaust gas burned in the cylinder discharged from the cylinder decreases, and the residual gas increases in the cylinder. Therefore, the so-called internal EGR increases, and the temperature of the exhaust gas discharged from the next cylinder decreases, so that the temperature of the catalyst provided in the exhaust pipe decreases.

When the catalyst temperature is lowered, the choice of whether to execute the retard control or the advance control is determined according to the operating state of the internal combustion engine. The method of the selection is not the gist of the present invention, and therefore the description is omitted.

(5) The exhaust gas temperature lowering means executes a reduced cylinder operation in which a part of the plurality of cylinders performs a reduced cylinder operation in which engine fuel is not injected or ignited when the internal combustion engine is operating. It is preferred to have means.

The "reduced cylinder operation executing means" is one of various application programs stored in the ROM for realizing the exhaust gas temperature lowering means.
Further, since the ECU stores the program relating to the exhaust gas temperature lowering means including the reduced cylinder operation executing means in the ECU, the ECU is referred to as the reduced cylinder operation executing means.

Here, the ignition sequence of an in-line four-cylinder engine will be described by way of example. In the case of an in-line four-cylinder engine, it corresponds to the first cylinder and the fourth cylinder, respectively, and
First and fourth crank pins located at both ends of the shaft, and second and third crank pins corresponding to the second and third cylinders and located at the center of the crank shaft, respectively. The pins are
When they are viewed from the axial direction of the crankshaft, they have a line-symmetric relationship with the crank journal. And a first crank pin and a fourth crank pin;
The angle between the second crank pin and the third crank pin, that is, the crank angle is always 180 °.

Therefore, when the first piston attached to the first crank pin is at the top dead center, the piston attached to the fourth crank pin is also located at the top dead center. Further, the pistons with the second crank pin and the third crank pin are both located at the bottom dead center.

Therefore, when the first piston moves toward the bottom dead center due to the explosion stroke of the first cylinder, the fourth piston moves toward the bottom dead center.
The fourth piston applied to the cylinder also moves toward the bottom dead center, and the operation stroke of the fourth cylinder at that time is the suction stroke.

Then, the second and third pistons of the second and third cylinders move toward the top dead center, and the operation strokes of the second and third cylinders are the compression stroke and the exhaust stroke, respectively. Will be either.

If the second cylinder is set to the compression stroke, the third cylinder is set to the exhaust stroke. Conversely, if the second cylinder is set to the exhaust stroke, the third cylinder is set to the compression stroke. Depending on the choice, the ignition order of the four-cylinder engine will be different.

Here, from the relation of good intake efficiency, an in-line four-cylinder engine, which is generally used, in which the second cylinder is in the exhaust stroke when the third cylinder is in the compression stroke, for example, the ignition order is 1-3 -4-2 In-line four-cylinder engine.

Then, "a part of the cylinders" is assumed to be a first cylinder. This part of the cylinder is not limited to the first cylinder, and may be any one of the second, third, and fourth cylinders. In addition to the first cylinder, a total of two or three cylinders including any one or two of the remaining three cylinders may be referred to as a part of the cylinders. The remaining cylinders other than some of the cylinders are referred to as unselected cylinders for convenience.

In the case where the engine is operated as the first cylinder as described above, a part of the first cylinder does not perform the injection and ignition of the engine fuel during the operation of the engine. As a result, the compression stroke and the explosion stroke, which should be performed for the first cylinder, are virtually eliminated, so that the crankshaft is rotated only by the unselected second to fourth cylinders. become.

Since the injection and ignition of the engine fuel are not performed in the first cylinder as described above, the compression stroke and the explosion stroke, which should be performed if the original engine operation is performed for the first cylinder, are executed. Instead of performing these steps, intake and exhaust are performed, respectively. As described above, during the operation of the internal combustion engine, as a result of performing the reduced cylinder operation without performing the injection and ignition of the engine fuel for a specific part of the cylinder,
The operation in which the intake air flows in and out without injecting and igniting the engine fuel to some of the cylinders is referred to as a pump operation for convenience.

When work is being performed only with the unselected cylinders, only the pump operation is performed in the first cylinder, and thus the high-temperature exhaust gas is not discharged from the first cylinder. For this reason, the temperature of the exhaust gas flowing out to the exhaust pipe decreases accordingly.

Therefore, the temperature of the exhaust gas discharged to the exhaust pipe is reduced by the amount that the first cylinder does not perform the substantial operation effective for generating the torque. Effective for lowering the temperature.

When this pump operation is performed for some of the cylinders, the unselected cylinders perform extra work because the part of the cylinders do not perform a substantial operation effective for generating torque. It is necessary to keep the engine output torque constant.

(6) Therefore, it is necessary to compensate for the torque generation that is sufficient for the part of the cylinders that do not work by the cylinders not selected. In other words, it can be said that there is a torque reduction correcting means for performing a torque reduction correction corresponding to a part of the cylinder that does not work. It is needless to say that the torque reduction correcting means is an unselected cylinder which is a cylinder other than the some cylinders. For the unselected cylinder, an increase in the engine fuel or an increase in the intake air amount is performed. Need to do.

In this manner, the output torque can be kept constant even when the cylinder-reducing operation is performed for some of the cylinders. It should be noted that performing the reduced cylinder operation where the crankshaft is originally rotated by four cylinders may cause a torque shock. Therefore, an experiment or a calculation is repeatedly performed so as to avoid the torque shock, and an execution condition for determining which cylinder is a part of the cylinder is determined.
In other words, it is necessary to select which cylinder should be a part of the cylinder.

In the case of a four-cylinder engine, if some of the cylinders are reduced to three, only one cylinder is not selected, and the load on the cylinder becomes extremely large. In this connection, it is desirable to replace one or two cylinders with some of the cylinders so that the load on the unselected cylinders does not increase significantly.

(7) In accordance with the operation state of the internal combustion engine, it is selected whether to execute the retard control or the advance control, or to execute the reduced cylinder operation in addition to any of these executions. As a selection unit, a reduction temperature ratio comparison unit that compares the reduction temperature ratio of the exhaust gas temperature with a specific predetermined value, and as a result of comparison by the reduction temperature ratio comparison unit,
When the decrease rate of the exhaust gas temperature is smaller than the specific predetermined value, the retard control or the advance control is executed, and when the decrease temperature rate of the exhaust gas temperature is equal to or more than the specific predetermined value, The reduced cylinder operation may be executed in addition to the execution of the retard control or the advance control.

Here, "execution of the retard control or execution of the advance control" means that either the execution of the retard control or the execution of the advance control is selectively performed depending on the operating state of the internal combustion engine. Means to run.

The "specific predetermined value" differs depending on the type of the catalyst, and when the temperature decrease rate is required to be higher than the specific predetermined value, the catalyst is substantially overheated and the retard control or the advancement is performed. Executing the angle control alone is not enough to reduce the catalyst temperature, and means a numerical value that becomes a reference indicating that the catalyst is in a high temperature state that is required to execute the reduced cylinder operation.

The "decreased temperature ratio comparing means" is used to realize various routines for executing control of the internal combustion engine.
M is one of various application programs stored in M. Further, since the attribute of the ROM storing the program relating to the temperature drop ratio comparing means is in the ECU, the ECU can be said to be the temperature drop rate comparing means.

In the internal combustion engine having the electromagnetically driven valve train according to the present invention, when the rate of decrease in the exhaust gas temperature is smaller than the specific value, the retard control or the retard control is performed in accordance with the operating state of the internal combustion engine. Executing the advance control, and executing the reduced cylinder operation in addition to the execution of the retard control or the execution of the advance control when the decrease temperature ratio of the exhaust gas temperature is equal to or more than the specific predetermined value. Therefore, it is possible to realize the optimal control for decreasing the catalyst temperature in accordance with the operating state of the internal combustion engine.

[0073]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment of an internal combustion engine having an electromagnetically driven valve train according to the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine having an electromagnetically driven valve operating mechanism according to the present invention. The internal combustion engine 1 shown in FIG. 1 has a plurality of cylinders (in this embodiment, four cylinders).
): First cylinder 21-1, second cylinder 21-2, third cylinder
And a fourth cylinder 21-4, each of which has an injector 32 for directly injecting fuel into the cylinder, and furthermore, the ignition order is 1-3-4.
This is a lean-burn gasoline engine with four in-line four cylinders performed in the order of -2 cylinders.

In the drawing, the cylinder is the first cylinder 21-1.
Only the first cylinder 21-1, the second cylinder 21-2, and the third cylinder 21- are shown from the near side to the far side in FIG.
The third and fourth cylinders 21-4 are arranged.

The internal combustion engine 1 has four cylinders 21-1,
21-2, 21-3, 21-4 (these cylinders may be collectively referred to simply by reference numeral 21) and a cylinder block 1b having a water jacket 2 as an engine cooling water passage. , This cylinder block 1
b and an oil pan 1c fixed to a lower portion of the cylinder block 1b.

Although not shown, the cylinder block 1b is also provided with a passage for lubricating oil. The cylinder block 1b rotatably supports a crank shaft 23 that is an engine output shaft. And this crank
The shaft 23 is connected via a connecting rod 3 to a piston 22 that is slidably mounted in each cylinder 21 on a crank journal (not shown).

Above the piston 22, when the piston 22 is at the top dead center, a combustion chamber is formed by the upper part of the cylinder 21, the piston head 22a, and the concave part 22b provided on the upper part (FIG. 1). Since the piston 22 is located before the top dead center, the reference numeral 24 indicates a space that has not yet become a combustion chamber.)

In the combustion chamber, compression and ignition of a mixture obtained by mixing intake air and engine fuel are performed.
The cylinder head 1a has an ignition plug 25 facing the combustion chamber, and an igniter 25a for applying a drive current to the ignition plug 25.

Further, two intake air ports 26, 26 (only one is shown in the drawing) and exhaust ports 27, 27 (only one is shown in the drawing) are respectively formed in the cylinder head 1a. Each open end faces the combustion chamber. Further, the injector 32 is attached to the combustion chamber so as to face the same.

The intake air ports 26, 26 are opened and closed by inlet valves 28, 28 (only one is shown in the drawing) which are suction valves whose opening ends are supported by the cylinder head 1a so as to be able to advance and retreat. .

The same applies to the exhaust ports 27, 27, and each open end thereof has an exhaust valve 2 which is an exhaust valve supported on the cylinder head 1a so as to be able to advance and retreat.
It is opened and closed by 9, 29 (only one is shown in the drawing).

The inlet valves 28, 28 and the exhaust valves 29, 29 are operated by the following electromagnetic drive mechanism for reciprocating these valves by utilizing electromagnetic force.
6, 26 and the exhaust ports 27, 27 are opened and closed. For convenience of explanation, the intake air ports 26, 26 and the exhaust port 2
Opening and closing of 7, 27 is synonymous with opening and closing of inlet valves 28, 28 and exhaust valves 29, 29.

The electromagnetic drive mechanism for operating the inlet valves 28, 28 is indicated by reference numeral 30, and hereinafter referred to as "the intake air side electromagnetic drive mechanism 30". In addition, exhaust
An electromagnetic drive mechanism that opens and closes the valves 29, 29 is indicated by reference numeral 31, and is hereinafter referred to as an “exhaust-side electromagnetic drive mechanism 31”.

Valves for operating the inlet valves 28, 28 and the exhaust valves 29, 29 of the internal combustion engine 1 by using the electromagnetic force generated by the intake air side electromagnetic drive mechanism 30 and the exhaust side electromagnetic drive mechanism 31, respectively. The mechanism is referred to as an electromagnetically driven valve train, and the intake air side electromagnetically driven valve train and the exhaust side electromagnetically driven valve train are indicated by reference numerals 30A and 31A, respectively.

The intake air side electromagnetically driven valve mechanism 30A and the exhaust side electromagnetically driven valve mechanism 31A are mounted for each cylinder. Here, the intake air side electromagnetically driven valve train 30
A (hereinafter, referred to as “intake air side electromagnetically driven valve 30A”) and the exhaust side electromagnetically driven valve train 31A (hereinafter, referred to as “exhaust side electromagnetically driven valve 31A”) will be described in detail. However, the two mechanisms 30A and 31A have the same configuration except for the name of the valve. Therefore, in this specification, one exhaust side electromagnetically driven valve 31A will be described in consideration of the subject matter of the invention, and description of the other intake air side electromagnetically driven valve 30A will be omitted.

In the exhaust-side electromagnetically driven valve 31A, the components of the exhaust valve 29, such as 29a and the like, are designated by reference numerals with alphabetical characters 29, so that the inlet valve of the intake air-side electromagnetically driven valve 30A is used. This shows that the valve members are substantially the same as but different from the related members of No. 28.

First, in FIG. 2, the cylinder head 1a of the internal combustion engine 1 includes a lower head 10 directly fixed to the upper surface of the cylinder block 1b and an upper head 11 provided on the upper part of the lower head 10. Prepare.

The lower head 10 is connected to the exhaust port 27,
A valve seat 12 for seating a valve body 29a of an exhaust valve 29 is provided at an open end of each exhaust port 27, 27 on the combustion chamber side.

A circular through-hole having a circular cross section is formed from the inner wall surface of each exhaust port 27 to the upper surface of the lower head 10, and the valve shaft 29b of the exhaust valve 29 is guided in this through hole so as to be able to advance and retreat. Cylindrical valve guide 13
Inset.

The upper head 11 has a core mounting hole 14 having a circular cross section. The core mounting hole 14 is located on the same axis 1 as the valve guide 13. The core mounting hole 14
It consists of a small-diameter portion 14a located above and a large-diameter portion 14b located below.

The small-diameter portion 14a has annular first and second cores 301 and 302 made of a soft magnetic material inserted into upper and lower end openings, respectively. Both cores 301 and 302
Are arranged in series in the axial direction with a predetermined space 303 therebetween. The flanges 30 are provided at the upper end of the first core 301 and the lower end of the second core 302, respectively.
1a and a flange 302a.

The first core 301 is located at the top of FIG. 2 and the second core 302 is located at the bottom of FIG.
4 is inserted. When the flanges 301a and 302a are fitted until they come into contact with the periphery of the core mounting hole 14, the first core 301 and the second core 302 are inserted.
However, further fitting into the small diameter portion 14a is prevented. Thereby, the dimension of the space 303 in the axial direction is determined. This dimension is determined mainly by the valve lift of the valve body 29a.

The first core 301 has a cylindrical upper cap 305 mounted thereon. The upper cap 305 has a flange portion 305a at its lower end. The first core 301 is positioned on the upper head 11 by fixing the flange portion 305a on the upper surface of the upper head 11 with the bolt 304.

An upper portion of the upper cap 305 is formed as an opening, and a screw groove is formed in this opening so that the adjusting bolt 313 can be screwed therein. On the other hand, the second core 30
2 positions the flange portion 302a on the upper head 11 via an annular lower cap 307, and fixes the flange portion 302a from below the lower cap 307 using bolts 306.

A circular groove is formed on the side surface of the space portion 303 of the first core 301, and the first groove is formed therein.
Is mounted. On the other hand, the second core 3
02, a circular groove is also formed on the side surface of the space 303,
The second electromagnetic coil 309 is mounted therein.

The first electromagnetic coil 308 and the second electromagnetic coil 309 oppose each other on the same axis l, and an exciting current is applied to each. In addition, the first core 301 and the second core 302 have through holes 301b and 302b at the center portion including the axis l, respectively.

On the other hand, a disk-shaped armature 311 made of a soft magnetic material is arranged between the space portions 303.
The armature 311 has a columnar armature shaft 310 extending vertically from its center. The upper half of the armature shaft 310 has the first core 30.
1 through the through hole 301b and the upper cap 305
And the lower half reaches the inside of the large-diameter portion 14b through the through hole 302b of the second core 302.

The armature 311 is connected to the space 3
03, that is, the armature 311 can be freely reciprocated in the vertical direction in FIG.
The diameter of 10 is somewhat narrower.

The armature shaft 310 extending into the upper cap 305 has a disc-shaped upper retainer 312 joined to its upper end in FIG. An upper spring 314 is interposed between the upper retainer 312 and the adjusting bolt 313. A spring seat 315 having an outer diameter substantially equal to the inner diameter of the upper cap 305 is interposed between the adjusting bolt 313 and the upper spring 314, and the lower surface of the spring seat 315 is provided. The upper spring 314 is provided in the concave portion 315a provided in
Is located so that the upper spring 314 does not come off from between the upper retainer 312 and the spring seat 315.

The armature shaft 310 extending into the large-diameter portion 14b is provided at its lower end in FIG. 2 at the opposite end of the exhaust valve 29 opposite to the side where the valve 29a is located. The armature shaft 310 and the exhaust valve 29 are positioned on the same straight line l.

A disc-shaped lower retainer 317 is joined to the outer periphery of the non-valve element side end portion 29d, and a lower spring is provided between the lower surface of the lower retainer 317 and the upper surface of the lower head 10. 316 is interposed. One end of the lower spring 316 is inserted into a concave portion 10a provided on the upper surface of the lower head 10 and is inserted into the lower spring 31.
6 does not come off from between the lower retainer 317 and the upper surface of the lower head 10.

The exhaust side electromagnetically driven valve 31A having such a configuration is described.
Are the first electromagnetic coil 308 and the second electromagnetic coil 30
When the exciting current is not applied to the armature shaft 9, the armature shaft 310 has a spring force of the upper spring 314 to urge the armature shaft 310 downward (that is, to open the exhaust valve 29) in FIG.・ Spring 3
The spring force of 16 acts on the upper side of FIG. 2 (that is, the direction of closing the exhaust valve 29).

At this time, the armature shaft 3
The spring force and lower force of the upper spring 314 are set so that the armature 311 and the exhaust valve 29 are placed in a so-called neutral state where they abut against each other and are elastically supported at a predetermined position and the armature 311 is located in the middle of the space 303.・
The spring force of the spring 316 is determined.

In addition, the armature 311 is
The axial direction of the armature shaft 310 and the valve shaft 29b is such that the valve body 29a is located at an intermediate position between the fully open position and the fully closed position (the position where the valve body 29a is located in FIG. Are set as appropriate.

When the position of the armature 311 is deviated from the intermediate position of the space 303 due to the initial tolerance or aging of the components of the exhaust side electromagnetically driven valve 31A, the armature 311 is adjusted by the adjustment bolt 313. Adjustment is made to return to the intermediate position of the space 303.

In the exhaust side electromagnetic drive mechanism 31, when an exciting current is applied to the first electromagnetic coil 308, the armature 311
Is generated toward the first core 301, and the second electromagnetic force is generated.
When an exciting current is applied to the electromagnetic coil 309, an electromagnetic force for displacing the armature 311 toward the second core 302 is generated.

In the exhaust-side electromagnetic drive mechanism 31, when an exciting current is alternately applied to the first electromagnetic coil 308 and the second electromagnetic coil 309, the armature 311 moves to the side of the applied electromagnetic coil, Thus, the valve body 29a operates to open and close the exhaust port 27. At this time, the opening / closing timing of the exhaust valves 29, 29 is controlled by changing the excitation current application timing and the magnitude of the excitation current to the first electromagnetic coil 308 and the second electromagnetic coil 309.

Further, each of the valve elements 29a of the exhaust valves 29, 29 provided two for each cylinder,
It can be opened and closed independently by opening and closing control by a drive circuit (not shown).

The exhaust-side electromagnetically driven valve 31A is arranged such that the cylinder-side valve 31A is slightly inclined with respect to the cylinder center line L.
Attached to the head 1a, the intake side electromagnetically driven valve 30A
At the same time, the scissor angle φ (see FIG. 1) changes the exhaust-side electromagnetically driven valve 31A with respect to the cylinder center line L of the valve shaft 29b.
Are installed so that the inclination angle of the air-conditioner can satisfy the requirements of the intake and exhaust performance.

Next, another configuration of FIG. 1 will be described. , The intake air ports 26 of each cylinder 21 of the internal combustion engine 1
Communicates with each branch pipe of the in-manifold 33 attached to the cylinder head 1a. And in Mani 33
Is connected to a surge tank 34 for smoothing the pulsation of the intake air, and an intake air pipe 35 is connected to the surge tank 34. The surge tank 34 is a vacuum tank that outputs an electric signal corresponding to the internal pressure.
It has a sensor 50.

In addition, the intake air pipe 35 is provided with an air cleaner box 3 for removing dust and dirt from the intake air.
6 is connected. The intake air pipe 35 has an air flow meter 44 that detects the amount of intake air flowing through the pipe as a voltage value and outputs an electric signal corresponding to the voltage value.

At a position downstream of the air flow meter 44 in the intake air pipe 35, a throttle valve 39 for controlling the amount of intake air is provided. The throttle valve 39 is composed of a stepper motor or the like. The throttle valve 39 throttles the throttle valve 39 according to the magnitude of the applied current and adjusts the opening area of the intake air pipe 35 according to the opening degree of the throttle valve 39. An actuator 40, a throttle position sensor 41 that detects an opening degree of the throttle valve 39 as a voltage value and outputs an electric signal corresponding to the voltage value, and an electric signal corresponding to the amount of depression of an accelerator pedal 42. It is combined with an accelerator position sensor 43 for outputting.

On the other hand, each exhaust port 27 of the internal combustion engine 1
The exhaust manifold 45 communicates with each branch pipe of the exhaust manifold 45 attached to the cylinder head 1a, and the exhaust manifold 45 communicates with an exhaust pipe 47 that is an exhaust passage.

The exhaust pipe 47 has a catalytic converter 46 in which an exhaust gas purifying catalyst is filled in the middle thereof, and a muffler (not shown) is attached downstream of the catalytic converter 46.

The exhaust manifold 45 further has an air-fuel ratio sensor 48 for outputting an electric signal corresponding to the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst of the catalytic converter 46 (hereinafter referred to as "exhaust air-fuel ratio").

The exhaust purification catalyst of the catalytic converter 46 stores NOx contained in the exhaust when the exhaust air-fuel ratio is lean, and stores the NOx when the exhaust air-fuel ratio is stoichiometric or rich. A storage-reduction type lean NOx catalyst that releases NOx that has been released and reduces the released NOx to purify the exhaust gas, and NO in the exhaust gas when the exhaust air-fuel ratio is a lean air-fuel ratio and a predetermined reducing agent is present.
A selective reduction type lean NOx catalyst that reduces x and purifies exhaust gas is applied.

A catalyst temperature sensor 49 for outputting an electric signal corresponding to the bed temperature of the exhaust gas purification catalyst is attached to the catalytic converter 46 containing such an exhaust gas purification catalyst.

The internal combustion engine 1 has a crank position sensor 51 including a timing rotor 51a attached to the end of the crankshaft 23 and an electromagnetic pickup 51b provided near the timing rotor 51a.
Having.

Further, the cylinder block 1b of the internal combustion engine 1 has a water temperature sensor 52 for detecting the temperature of the cooling water flowing through the water jacket 2. The operating state of the internal combustion engine 1 having such a configuration is controlled by the ECU 20.

The ECU 20 has a throttle position
Various sensors such as a sensor 41, an accelerator position sensor 43, an air flow meter 44, an air-fuel ratio sensor 48, a catalyst temperature sensor 49, a vacuum sensor 50, a crank position sensor 51, and a water temperature sensor 52 are electrically connected. Are connected, and the output signal of each sensor is input to the ECU 20.

The ECU 20 includes an igniter 25a,
Intake air side electromagnetic drive mechanism 30, exhaust side electromagnetic drive mechanism 3
1, injector 32, throttle actuator 4
0, etc., and controls the igniter 25a, the intake air side electromagnetic drive mechanism 30, the exhaust side electromagnetic drive mechanism 31, and the injector 32 which is a fuel injection valve based on output signals from the various sensors.

In addition, as shown in FIG. 3, the ECU 20 includes a central processing controller CPU 401 and a read-only memory R connected to each other via a bidirectional bus 400.
OM 402 and random access memory RAM 40
3, a backup RAM 404, an input port 405 as an input interface circuit, an output port 406 as an output interface circuit, and the input port 405.
A / D converter (hereinafter “A / D”) connected to
That. ) 407.

Sensors that output analog signals such as a throttle position sensor 41, an accelerator position sensor 43, an air flow meter 44, an air-fuel ratio sensor 48, a catalyst temperature sensor 49, a vacuum sensor 50, and a water temperature sensor 52. Is input to the input port 405 via the A / D 407, and the signal input to the input port 405 is input to the CPU via the bidirectional bus 400.
The data is transmitted to 401 and RAM 403.

The input port 405 receives the output signal of a sensor that outputs a digital signal such as the crank position sensor 51 as it is. In this case, the signal input to the input port 405 is transmitted to the CPU 401 via the bidirectional bus 400 as described above.
Or to the RAM 403.

The output port 406 receives control signals output from the CPU 401 through the igniter 25a, the intake air side electromagnetic drive mechanism 30, the exhaust side electromagnetic drive mechanism 31, the injector 32 serving as a fuel injection valve, and the throttle actuator 4.
Send to 0.

The ROM 402 stores application programs for implementing various routines.
The routine includes, for example, a fuel injection amount control routine for determining the fuel injection amount (TAU) by the injector 32, a fuel injection timing control routine for determining the fuel injection timing, and opening of the inlet valves 28, 28. An inlet valve opening timing control routine for determining the timing, an exhaust valve opening timing control routine for determining the opening timing of the exhaust valves 29, 29, and the ignition timing of the spark plug 25 of each cylinder 21 are determined. The ignition timing control routine for determining, the throttle opening control routine for determining the opening of the throttle valve 39, and the timing of applying the exciting current to the intake air side electromagnetic drive mechanism 30 and the exhaust side electromagnetic drive mechanism 31 are changed. Excitation current control loop to execute torque control by valve timing Even if the temperature of the exhaust purification catalyst contained in the catalytic converter 46 becomes higher than the catalyst activation temperature, which is a predetermined required temperature, depending on the operation state of the engine 1, the catalyst may reach the activation temperature of the catalyst. Of the exhaust gas temperature reduction control routine according to the present invention for lowering the temperature of the exhaust gas.

The ROM 402 stores various control maps in addition to the application programs for implementing the various routines described above. For example, a fuel injection amount control map showing the relationship between the engine operating state and the fuel injection amount, a fuel injection timing control map (not shown) showing the relationship between the engine operating state and the fuel injection timing, the engine operating state and the inlet valve 28 Valve opening / closing timing control map showing the relationship between the opening / closing timing of the engine, exhaust valve opening / closing timing control map showing the relationship between the engine operating condition and the opening / closing timing of the exhaust valve 29, the engine operating condition and the intake air side electromagnetic drive mechanism 30 and exhaust side electromagnetic drive mechanism 3
1, an excitation current amount control map showing the relationship between the amount of the excitation current applied to the ignition plug 1, an ignition timing control map showing the relationship between the engine operation state and the ignition timing of each ignition plug 25, the engine operation state and the opening of the throttle valve 39. The throttle opening control map showing the relationship between the temperature and the engine load, according to the present invention, calculates the reduction rate T2 of the exhaust gas temperature required to make the catalyst temperature the active temperature based on the current catalyst temperature and the current engine load. And a control map for controlling the rate of decrease in exhaust gas temperature.

The RAM 403 stores output signals of various sensors, calculation results of the CPU 401, and the like. The calculation result is, for example, an engine speed calculated based on an output signal of the crank position sensor 51 or the like. The R
Various data stored in the AM 403 is rewritten to the latest data every time the crank position sensor 51 outputs a signal.

The backup RAM 404 stores the internal combustion engine 1
Is a non-volatile memory that retains data even after the operation is stopped, and stores learning values and the like related to various controls. CPU 401
Operates according to an application program stored in the ROM 402 to execute fuel injection control, inlet valve opening / closing control, exhaust valve opening / closing control, ignition control, excitation current control, catalyst temperature control, and the like.

Next, a program for realizing the exhaust gas temperature lowering control routine according to the present invention will be described with reference to FIG. In S101, it is determined whether or not the catalyst temperature detected by the catalyst temperature sensor 49 is higher than an activation temperature T1, which is a predetermined temperature. If an affirmative determination is made, the process proceeds to S102, and if a negative determination is made, this routine ends. In this embodiment, the catalyst temperature is detected by the catalyst temperature sensor 49.
4 means for estimating the catalyst temperature from the integrated value of the intake air amount per unit time detected, for example, stored in the read-only memory ROM, taking the integrated value of the intake air amount on the vertical axis and taking the time on the horizontal axis. The catalyst temperature may be predicted using the catalyst temperature detection map, and the determination may be made based on whether the catalyst temperature predicted from the catalyst temperature detection map is higher than the activation temperature T1.

The internal combustion engine 1 having the electromagnetically driven valve operating mechanism according to the present invention has an object to reduce the catalyst temperature to the catalyst activation temperature when the catalyst temperature becomes too high than the catalyst activation temperature T1. Therefore, if the determination is affirmative, this routine is continued, and if the catalyst temperature is lower than the activation temperature T1, which is the predetermined temperature, the determination is made as non-target and the determination is negative, and this routine is terminated.

This step S101 is referred to as catalyst temperature determining means because the temperature of the exhaust gas purifying catalyst is compared with the predetermined required temperature (T1) to determine whether the catalyst is in a high temperature state.

S101 is one of the programs constituting the exhaust gas temperature lowering control routine. The exhaust gas temperature lowering control routine is stored in the ROM of the ECU 20,
The attributes of the ROM are in the ECU 20. Therefore, the ECU 20
Can be referred to as catalyst temperature determination means.

When the catalyst temperature is higher than the predetermined required temperature (T1), that is, when the catalyst temperature is in a high temperature state, the process proceeds.
In step 102, a decrease rate T2 of the exhaust gas temperature required to make the catalyst temperature the active temperature is calculated based on the current catalyst temperature and the current engine load. The exhaust gas temperature decrease rate T2 is obtained from the exhaust gas temperature decrease rate control map (not shown).

The ECU 20 as the catalyst temperature determining means
If it is determined in (S101) that the temperature of the catalyst is higher than the predetermined required temperature (T1), the temperature of the exhaust gas required to lower the temperature of the catalyst to the predetermined required temperature (T1) is determined. It is S1 to calculate the decrease ratio (T2).
Since it is 02, S102 is referred to as an exhaust gas temperature decrease ratio calculating means.

S102 is one of the programs constituting the exhaust gas temperature lowering control routine. The exhaust gas temperature lowering control routine is stored in the ROM of the ECU 20,
The attributes of the ROM are in the ECU 20. Therefore, the ECU 20
This can be referred to as exhaust gas temperature decrease ratio calculation means.

Note that T2 may be obtained from an appropriate calculation formula without depending on the map. In S103, S
It is determined using the inequality T2 <TA whether or not T2 determined in step 102 is small in relation to a specific predetermined value TA which is an appropriate comparison temperature.

The "specific predetermined value (TA)" differs depending on the type of the catalyst, and when the temperature drop rate (T2) is required to be higher than the specific predetermined value, the catalyst is in a state of being overheated considerably, This is a reference value indicating that the catalyst is in such a high temperature state that the execution of the control or the execution of the advance angle control alone is insufficient to reduce the catalyst temperature, and the execution of the reduced cylinder operation is also required. is there.

If the determination is affirmative in S103, the process proceeds to S104, and if the determination is negative in S101, that is, T2 ≧ T
In the case of A, the process proceeds to S105. In S104, the retard control or the advance control of the exhaust valve 29 is executed, and then this routine ends. The retard control or the advance control of the exhaust valve 29 is referred to as correcting the valve timing. In addition, S104 is set to retard control /
This is referred to as advanced angle control execution means.

Here, the general opening / closing timing of the exhaust valve (hereinafter referred to as “the base opening / closing timing of the exhaust valve”) will be described with reference to FIG. FIG. 5 is a valve timing diagram showing the opening and closing timing of the exhaust valve in terms of the crank angle.

Both ends of a thick double-headed arrow (hereinafter, referred to as a “base line”) shown in the figure have opening / closing timings (hereinafter, “base opening / closing timings”) serving as bases of an exhaust valve.
That. ).

Reference numeral 23 denotes the end face of the crankshaft described above. In this figure, the crankshaft 23 is shown rotating in a clockwise direction. The thin arrows and points (a) and (b) in the figure will be described later in the description of the opening / closing timing of the exhaust valve 29 according to the present embodiment.

Generally, the exhaust valve does not open and close when the piston is at the top dead center or the bottom dead center, but is set so as to be at the most suitable time for improving engine performance.

A. When to Open the Exhaust Valve The most common timing of opening and closing the exhaust valve base is before the bottom dead center, where the explosion process ends. In other words, the exhaust
The valve is opened when the piston is depressed during the explosion stroke and approaches the vicinity of the bottom dead center.

The reason is that opening the exhaust valve after the piston enters the ascending stroke causes a large loss of power, and also uses the gas pressure during the explosion stroke in which the internal pressure of the cylinder still remains. This is because if the gas is discharged, the exhaust gas can be efficiently discharged.

B. When to Close the Exhaust Valve Of the exhaust valve base opening and closing timing, the general timing of closing the exhaust valve is after the top dead center at which the exhaust stroke ends.

The reason is that it is necessary to discharge the residual gas as much as possible in order to sufficiently inhale and increase the output of the internal combustion engine. Also, it is preferable to keep the exhaust valve open for a certain time after the start of the suction stroke. Also, considering the compressibility and inertia of the gas, the exhaust gas can be efficiently discharged by using the gas compressibility and the inertia. Therefore, the exhaust valve is kept open for a certain time after the start of the suction stroke.

Further, with reference to FIG. 5, the opening / closing timing of the exhaust valve 29 according to the present embodiment will be shown in comparison with the base opening / closing timing of the general exhaust valve. In the internal combustion engine 1, the exhaust valve 2 is controlled by executing the retard control or the advance control of the exhaust valve 29.
9 is opened and closed.

The execution of the retard control of the exhaust valve 29 is performed by opening the exhaust valve 29 when the opening timing of the exhaust valve 29 is later than the opening timing of the base timing and the crank angle is after the bottom dead center. is there.

The execution of the advance angle control is to close the exhaust valve 29 earlier than the closing timing at the base timing of the exhaust valve 29 and when the crank angle is in the state before the top dead center.

The opening timing of opening the exhaust valve 29 by executing the retard control is executed at a point (a) later than the opening timing of the baseline. If the retard control is performed at this point (a), the timing at which the exhaust gas burned in the cylinder 21 is discharged from the cylinder 21 to the exhaust pipe is after the exhaust gas temperature has somewhat decreased in the cylinder 21. Therefore, the temperature of the catalyst contained in the catalytic converter 46 provided in the exhaust pipe 47 can be reduced.

Further, if the retard control of the exhaust valve 29 is performed, the combustion ratio increases accordingly. Therefore, it also contributes to prevention of afterburn in the exhaust pipe 47. Next, the closing timing of closing the exhaust valve 29 by executing the advance angle control is executed at a point (b) earlier than the closing timing of the baseline.

When the advance angle control is performed at the point (b), the period during which the exhaust valve 29 is open is shortened accordingly.
The amount of exhaust gas exhausted from the cylinder 21 discharged from the cylinder 21 decreases, and the amount of residual gas in the cylinder 21 increases. Therefore, the so-called internal EGR increases, and the temperature of the exhaust gas discharged from the next cylinder decreases, so that the temperature of the catalyst provided in the exhaust pipe 47 can be reduced.

Whether to perform the retard control or the advance control is selected depending on the operating state of the internal combustion engine 1. The method of the selection is not the gist of the present invention, and the description is omitted.

Returning to FIG. In S105, as in S104, retard control or advance control of the exhaust valve 29 is executed. Also, S104 and S105 are referred to as retard control / advance control execution means.

S10 as retard / advance control execution means
Steps S4 and S105 are one of the programs that constitute the exhaust gas temperature reduction control routine. The exhaust gas temperature reduction control routine is stored in the ROM of the ECU 20, and the attribute of the ROM is in the ECU 20. Therefore, the ECU 20 can be referred to as retard control / advance control execution means.

In S106, the exhaust gas in S105
In addition to the execution of the retard control or the advance control of the valve 29, the cylinder 21-1 that is a part of the cylinders 21 performs the reduced cylinder operation in which the engine fuel is not injected and the ignition is not performed when the internal combustion engine 1 is operated. Execute. This is because T2 ≧
This is because the TA is premised, and the execution of only the retard control or the advance control of the exhaust valve 29 may not sufficiently reduce the temperature of the catalyst. Note that S106 is referred to as reduced cylinder operation execution means.

S106, which is a reduced cylinder operation execution means, is one of programs constituting an exhaust gas temperature lowering control routine. The exhaust gas temperature lowering control routine is stored in the ROM of the ECU 20, and the attribute of the ROM is in the ECU 20. .
Therefore, the ECU 20 can be referred to as a reduced cylinder operation execution unit.

Here, the ignition sequence of the internal combustion engine 1 which is an in-line four-cylinder engine will be described with reference to FIG. In the case of an inline four-cylinder engine, the crankshaft 2 corresponds to the first cylinder 21-1 and the fourth cylinder 21-4, respectively.
3 correspond to the first and fourth crank pins (not shown) and the second and third cylinders 21-2 and 21-3, respectively, and are located at the axial center of the crank shaft 23. The second crank pin and the third crank pin (not shown)
When the shaft 23 is viewed in the axial direction, a crank (not shown)
It is symmetrical with the journal.

The angle between the first crank pin and the fourth crank pin and the second crank pin and the third crank pin, that is, the crank angle is always 1
80 °.

In the internal combustion engine 1, the ignition order is
This is an in-line 4-cylinder 4-cycle engine performed in the order of 4-2 cylinders. Thus, when the first piston 22 attached to the first crank pin is at top dead center, the piston 22 attached to the fourth crank pin is also at top dead center. Also, the piston 22 with the second and third crank pins attached is both at the bottom dead center.

Accordingly, when the first piston 22 moves toward the bottom dead center due to the explosion stroke of the first cylinder 21-1, the fourth piston 22 applied to the fourth cylinder 21-4
Also moves toward the bottom dead center, and the operation stroke of the fourth cylinder 21-4 at that time is the suction stroke.

Then, the second piston 22 and the third piston 22 of the second cylinder 21-2 and the third cylinder 21-3 move toward the top dead center, and move to the second cylinder 21-2. The operation stroke of the third cylinder 21-3 shifts to an exhaust stroke and a compression stroke, respectively.

For the sake of convenience, the first cylinder 21-1 is tentatively named "a part of the cylinders", and the remaining second to fourth cylinders are named.
Cylinders 21-2 to 21-4 are referred to as unselected cylinders.

The first cylinder 21-1 which is a part of the cylinders
With regard to the above, the reduced-cylinder operation in which the engine fuel is not injected and ignited during the operation of the internal combustion engine 1 is performed, and the crank- A torque for rotating the shaft 23 is output.

During the operation of the internal combustion engine 1, some of the cylinders 21-1
Performs the reduced-cylinder operation as described above (see S106). As a result, in some of the cylinders 21-1, the relevant cylinder 2
At the time of execution of the compression stroke and the explosion stroke, which should be performed if the original engine operation is executed at 1-1, exhaust and intake are performed instead of performing these strokes, respectively.

As described above, during the operation of the internal combustion engine 1, the reduced cylinder operation in which the engine fuel is not injected and ignited for a specific part of the cylinders (cylinder 21-1) results in a specific part of the cylinders. The operation in which the intake air flows in and out of 21-1 is referred to as a pump operation for convenience.

Then, the cylinder not selected: second
When the first to fourth cylinders 21-2 to 21-4 are working with the torque generated during the explosion stroke, the first cylinder 21-1 simply repeats the pump operation. No high-heat exhaust gas is discharged from the cylinder 21-1. Therefore, the temperature of the exhaust gas flowing out to the exhaust pipe 47 decreases accordingly.

Therefore, since the first cylinder 21-1 does not operate effectively for generating torque, the temperature of the exhaust gas discharged to the exhaust pipe 47 is reduced by that much. Then, the temperature of the catalyst contained in the catalytic converter 46 provided in the exhaust pipe 47 is appropriately lowered.

On the other hand, when the pump operation is performed in the first cylinder 21-1, the unselected second cylinder 21-2
The fourth to fourth cylinders 21-4 need to perform extra work because the first cylinders 21-1 do not operate effectively for generating torque.

That is, the first cylinder 21-1 performs the torque reduction correction corresponding to the work not performed by the first cylinder 2-1.
Unselected second cylinder 2 other than 1-1
This needs to be performed in the first to fourth cylinders 21-4. Since the second cylinder 21-2 to the fourth cylinder 21-4 perform the torque reduction correction, the second cylinder 21-2 to the fourth cylinder 21-4 are referred to as a torque reduction correction unit.

Therefore, when performing the torque reduction correction,
Regarding the second cylinder 21-2 to the fourth cylinder 21-4,
Increasing engine fuel by the injector 32
It is necessary to increase the amount of intake air by increasing the opening of the valve 39.

However, by increasing the amount of engine fuel for the second cylinder 21-2 to the fourth cylinder 21-4, the cylinder 21 is increased.
If the amount of increase in the amount of heat generated in -2 to 4 becomes too high, the temperature of the catalyst may be increased rather than lowered. Therefore, while adjusting the retard control and the advance control to prevent such a situation, the throttle /
The opening degree of the valve 39 is appropriately adjusted, and the amount of intake air sent to the catalyst of the catalytic converter 46 by the pump operation of the cylinder 21-1 is increased.

By doing so, the first cylinder 21-
Even if the reduced-cylinder operation is performed for No. 1, the output torque of the entire engine can be kept constant, and the catalyst temperature can be reduced.
It should be noted that performing the reduced-cylinder operation where the crankshaft 23 should be rotated by four cylinders may cause a torque shock. Therefore, it is necessary to repeatedly perform experiments or calculations to determine the execution condition of which cylinder is to be a part of the cylinder, in other words, to select which cylinder is to be the part of the cylinder so as to avoid the torque shock. There is.

In the case of an in-line four-cylinder engine, if some of the cylinders are temporarily reduced to three, only one cylinder is not selected, and the load on the cylinder becomes extremely large.
In this connection, one or two cylinders are turned into some cylinders,
The load on the unselected cylinder is not significantly increased.

As is apparent from the above description, when the temperature of the exhaust gas purifying catalyst is higher than the predetermined required temperature (T1), the exhaust side electromagnetic drive mechanism 31 is operated to operate the exhaust valve 29. The valve timing of the exhaust gas is corrected or the number of cylinders is reduced, so that the temperature of the exhaust gas discharged from the internal combustion engine 1 is reduced, and the temperature of the exhaust purification catalyst is set to the predetermined required temperature (T1). S104 to S106 are referred to as exhaust gas temperature lowering means.

Steps S104 to S106 are one of programs constituting an exhaust gas temperature reduction control routine.
The exhaust gas temperature lowering control routine is stored in the ROM of the ECU 20, and since the attribute of the ROM is in the ECU 20, the
U20 can be referred to as catalyst temperature determination means.

In S103, it is determined whether the retard control or the advance control is executed or the reduced cylinder operation is executed in addition to any of the executions in accordance with the operating state of the internal combustion engine 1. Means for selecting the temperature, that is, the temperature decrease rate (T2) of the exhaust gas temperature is set to a specific predetermined value.
It can be said that this is a means for comparing the reduced temperature ratio with (TA). The execution of the retard control or the execution of the advance control means that either the execution of the retard control or the execution of the advance control is selectively executed in accordance with the operation state of the internal combustion engine. That is clear from the above explanation.

S103, which is a means for comparing the reduced temperature ratio,
The exhaust gas temperature lowering control routine is one of programs constituting the exhaust gas temperature lowering control routine.
Since the ROM 20 is stored in the ROM 0 and the attribute of the ROM is in the ECU 20, the ECU 20 can be referred to as a reduced temperature ratio comparing unit.

In the internal combustion engine 1, as a result of the comparison by the ECU 20, which is the temperature decrease ratio comparing means, the decrease ratio (T2) of the exhaust gas temperature becomes the specific predetermined value (TA).
If it is smaller than the predetermined value, the retard control or the advance control is executed in S104, and the decrease temperature ratio of the exhaust gas temperature is reduced.
If (T2) is equal to or greater than the specific predetermined value (TA), S1
At 05, the execution of the retard control or the advance control is performed, and at S106, the internal combustion engine executes the reduced cylinder operation after the execution of S105.

The above-described exhaust gas temperature lowering control routine is repeatedly executed by the CPU 401 in accordance with the operating state of the internal combustion engine 1 as appropriate. As is clear from the above description, when the temperature of the exhaust gas purification catalyst is higher than the predetermined required temperature (T1), the internal combustion engine 1 performs the exhaust-side electromagnetic drive mechanism 3 operation.
The operation of 1 corrects the valve timing of the exhaust valve 29 and / or performs reduced cylinder operation,
Through these processes, the temperature of the exhaust gas discharged from the internal combustion engine 1 can be reduced, and the temperature of the exhaust gas purification catalyst can be reduced to the predetermined required temperature (T1).

Therefore, in the internal combustion engine 1, even if the temperature of the exhaust gas purifying catalyst becomes higher than the predetermined required temperature, for example, the activation temperature of the catalyst, depending on the operation state of the internal combustion engine, the exhaust gas temperature decreases. The means E
The CU 20 lowers the temperature of the catalyst to the predetermined required temperature. As a result, the catalyst temperature is prevented from excessively increasing, and the exhaust gas purifying function of the catalyst is effectively exhibited during operation of the engine.

In the internal combustion engine 1, the ECU 2 serving as a lowering temperature ratio comparing means corresponds to the operating state of the internal combustion engine 1.
0 indicates that the exhaust gas temperature decrease rate (T2) is smaller than the specific predetermined value (TA), the retard control or the advance control is executed, and the exhaust gas temperature decrease rate (T2) ) Is equal to or larger than the specific predetermined value (TA), the reduced cylinder operation is performed in addition to the execution of the retard control or the advance control, and therefore, the catalyst optimal for the operating state of the internal combustion engine is provided. It is possible to realize the temperature reduction control.

In this embodiment, the valve timing of the exhaust valve 29 is corrected by the ECU 20 as the means for lowering the exhaust gas temperature, and the temperature of the catalyst is lowered by this correction. Alternatively, at least a well-known mechanism capable of changing the valve head of the exhaust valve 29 is employed in the exhaust-side electromagnetic drive mechanism 31 at least, so that the head amount of the exhaust valve 29 can be corrected so that the catalyst temperature can be corrected. It is also conceivable to reduce this.

Further, by appropriately correcting the valve timing and the head of the exhaust valve 29 in accordance with the operating state of the internal combustion engine 1, the temperature of the exhaust gas discharged from the internal combustion engine 1 is lowered, and It is also possible to lower the temperature of the catalyst to the predetermined required temperature (T1).

In the internal combustion engine 1, the temperature of the exhaust gas purifying catalyst is compared with the predetermined required temperature (T1) by the ECU 20 as catalyst temperature judging means to judge whether or not the temperature is high. Therefore, it can be reliably determined that the temperature of the exhaust purification catalyst is higher than the predetermined required temperature (T1).

Further, since the rate of decrease in the exhaust gas temperature can be calculated by the ECU 20 as the means for calculating the rate of decrease in the exhaust gas temperature, the temperature of the catalyst can be accurately reduced to the predetermined required temperature (T1). (Application Example) Next, an application example of an internal combustion engine having an electromagnetically driven valve train according to the present invention will be described.

The internal combustion engine according to this application is different from the above-described internal combustion engine 1 in that, in addition to the execution of the advance angle control relating to the exhaust valve 29, when the crank angle is in a state after the top dead center, the inlet valve The only difference is that the opening timing of the valve 28 is controlled to be later than the general opening timing of the inlet valve (hereinafter referred to as "execution of the retard control for the inlet valve"). Therefore, only the differences between the two will be described.

Here, the general opening / closing timing of the inlet valve will be described with reference to FIG. FIG. 7 is a valve timing diagram in which the opening and closing timing of the inlet valve is represented by a crank angle.

Both ends of a thick double-headed arrow (hereinafter, referred to as a “base line”) in the figure indicate an opening / closing timing (hereinafter, referred to as a “base opening / closing timing”) serving as a base of the inlet valve. Also, in FIG.
3 shows a state rotating clockwise. Note that the thin line arrow and the point (a) in the figure will be described later in the description of the opening timing of the inlet valve 28 according to the application example.

In general, the inlet valve does not open and close when the piston is at the top dead center or the bottom dead center, but is set so as to be the most suitable time for improving engine performance.

A. When to open the inlet valve The typical time to open the inlet valve is before the end of the exhaust stroke, at top dead center. This adjusts the slight delay between the opening of the inlet valve and the admission of the air-fuel mixture, and the momentum of the air-fuel mixture flowing into the cylinder while the exhaust valve is open (inlet inertia). ) Also serves as a scavenging effect for driving out residual gas. If this opening time is advanced, the backflow of the residual gas to the intake side increases, and the engine performance decreases, but NOx decreases. Therefore, the optimal time is determined in consideration of the balance.

B. When to close the inlet valve In general, the inlet valve closes the inlet valve in order to draw a sufficient mixture into the cylinder due to the compressibility due to the volume of the intake air pipe and cylinder and the inertia of the mixture flow. It is said that some time after the bottom dead center has passed.

Further, referring to FIG. 7, the opening timing of the inlet valve 28 of the internal combustion engine according to this application example is shown in comparison with the opening timing of the inlet valve among the base opening / closing timings of the inlet valve.

In the internal combustion engine according to this application example, as described above, in addition to the execution of the advance angle control of the exhaust valve 29, the execution of the above-described retard control of the inlet valve 28 allows the point (a) to be obtained. Open inlet valve 28.

In this case, in addition to utilizing the residual gas by executing the advance control of the exhaust valve 29 and correcting the valve timing to execute the retard control of the inlet valve 28, Since the internal EGR can be secured stably, the exhaust gas temperature decreases. For this reason, since the exhaust gas discharged to the exhaust pipe is discharged in a state where the exhaust gas temperature is lowered, the temperature of the catalyst provided in the exhaust pipe can be lowered.

In the above embodiment, the temperature of the exhaust gas discharged from the cylinder is lowered by correcting at least the valve timing or / and the lift of the exhaust valve of the inlet valve and the exhaust valve. Although the technology for lowering the temperature of the purification catalyst has been described, it is conceivable that the temperature of the exhaust purification catalyst may be lowered even with the inlet valve alone.

For example, the following two techniques can be exemplified. (1) The actual compression ratio is lowered by late closing the inlet valve at 90 ° after top dead center or early closing at 90 ° before top dead center. (2) Only one of the two intake valves is operated, that is, a so-called one-valve operation is performed to change the state of swirl generated in the cylinder to reduce the combustion speed.

[0200]

In an internal combustion engine having an electromagnetically driven valve operating mechanism according to the present invention, for example, a lean NO.
The temperature of the x catalyst and other catalysts can be suppressed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine having an electromagnetically driven valve train according to the present invention;

FIG. 2 is a diagram showing a configuration of an exhaust-side electromagnetically driven valve train;

FIG. 3 is a block diagram showing an internal configuration of an ECU.

FIG. 4 is a flowchart showing an exhaust gas temperature reduction control routine.

Fig. 5 Valve timing diagram showing the opening and closing timing of the exhaust valve in terms of crank angle

FIG. 6 is a diagram showing a relationship between an ignition sequence and an operation stroke of an in-line four-cylinder engine;

FIG. 7 is a valve timing diagram showing the opening / closing timing of an inlet valve as a crank angle.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 1a Cylinder head 1b Cylinder block 1c Oil pan 2 Water jacket 3 Connecting rod 10 Lower head 11 Upper head 12 Valve seat 13 Valve guide 14 Core mounting hole 14a Small diameter of core mounting hole 14b Core mounting Larger portion of hole 20 ECU (exhaust gas temperature lowering means, catalyst temperature determining means, exhaust gas temperature lowering rate calculating means, lowering temperature rate comparing means, retarding / advancing control executing means, reduced cylinder operation executing means) 21 General name of cylinder 21-1 First cylinder (some cylinders) 21-2 Second cylinder (cylinders other than some cylinders,
21-3 Third cylinder (cylinders other than some cylinders,
21-4 Fourth cylinder (cylinders other than some cylinders,
Torque reduction correcting means) 22 Piston 22a Piston head 22b Concave portion provided on top of piston head 23 Crank shaft 24 In-cylinder space before formation of combustion chamber 25 Spark plug 25a Igniter 26 Intake air port 27 Exhaust port 28 Inlet Valve (intake valve) 29 Exhaust valve (exhaust valve) 29a Exhaust valve valve element 29b Exhaust valve valve shaft 29d Exhaust valve end 30 Intake air side electromagnetic drive mechanism 30A Intake air side electromagnetic drive valve mechanism 31 Exhaust side electromagnetic drive mechanism 31A Exhaust side electromagnetic drive type valve train 32 Injector 33 In manifold 34 Surge tank 35 Intake air pipe 36 Air cleaner box 39 Throttle valve 40 Throttle actuator 41 Slot Torque position sensor 42 Accelerator pedal 43 Accelerator position sensor 44 Air flow meter 45 Exhaust manifold 46 Catalytic converter 47 Exhaust pipe 48 Air-fuel ratio sensor 49 Catalyst temperature sensor 50 Vacuum sensor 51 Crank position sensor 51a Timing rotor 51b Electromagnetic pick-up 52 Water temperature sensor 301 First core 301a Flange 301b Through hole 302 Second core 302a Flange 302b Through hole 303 Space 304 Bolt 305 Upper cap 305a Flange 306 Bolt 307 Lower cap 308 First 309 second electromagnetic coil 310 armature shaft 311 armature 312 upper retainer 313 adjustment bolt 314 upper spring Pulling 315 Spring seat 315a Recess 316 Lower spring 317 Lower retainer 400 Bidirectional bus 401 CPU 402 ROM 403 RAM 404 Backup RAM 405 Input port 406 Output port 407 A / D converter L Cylinder center line T1 Predetermined required temperature T2 Exhaust gas temperature decrease ratio TA T2 Comparison temperature l Axis center φ Scissor angle

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 17/02 F02D 17/02 M 43/00 301 43/00 301Z 301H (72) Inventor Kazuhiko Shiratani Aichi 1 Toyota Town, Toyota City Inside Toyota Motor Corporation (72) Inventor Keiji Yoda 1 Toyota Town Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Hideyuki Nishida 1 Toyota Town Toyota City, Aichi Prefecture Toyota (72) Inventor Tomomi Yamada 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Takamitsu Asanuma 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Yoshihiro Iwashita 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Kiyoshi Nakanishi Aichi 1 Toyota Town Toyota City F-term (reference) 3G018 AB09 AB16 CA12 DA36 DA37 DA38 DA39 DA40 DA41 EA31 EA32 FA06 FA07 FA12 GA09 GA24 GA27 3G084 BA13 BA16 BA23 DA10 DA19 EA11 EB12 EC02 EC03 FA18 FA27 FA38 FA39 3G09 AA09 AA11 AA14 BA08 BB01 CA04 CB04 CB05 DA07 DC15 DG09 EA04 FA17 FA18 FA20 FA37 HA11Z HD02Z HE01Z HE03Z HE05Z

Claims (7)

[Claims] An electromagnetically driven valve mechanism having an electromagnetic drive mechanism for opening and closing an intake / exhaust valve of an internal combustion engine using electromagnetic force, and an electromagnetically driven valve mechanism provided in an exhaust passage of the internal combustion engine having a plurality of cylinders. An exhaust gas purifying catalyst for purifying exhaust gas discharged from the cylinder and flowing into the exhaust passage; and when the temperature of the exhaust gas purifying catalyst is higher than expected or expected to be higher than a predetermined required temperature, at least the intake and exhaust Activating the electromagnetic drive mechanism according to the exhaust valve of the valves,
Exhaust gas temperature reduction that corrects the valve timing and / or head of the exhaust valve to lower the temperature of the exhaust gas discharged from the cylinder to lower the temperature of the exhaust purification catalyst to the predetermined required temperature. With means,
An internal combustion engine having an electromagnetically driven valve mechanism. 2. The electromagnetic apparatus according to claim 1, further comprising: a catalyst temperature determining unit that compares the temperature of the exhaust gas purification catalyst with the predetermined required temperature to determine whether the catalyst is in a high temperature state. An internal combustion engine having a driven valve train. 3. When the catalyst temperature determining means determines that the temperature of the catalyst is higher than the predetermined required temperature,
3. The electromagnetically driven valve according to claim 2, further comprising an exhaust gas temperature reduction ratio calculating means for calculating a reduction ratio of the exhaust gas temperature required to reduce the temperature of the catalyst to the predetermined required temperature. An internal combustion engine having a mechanism. 4. The exhaust gas temperature lowering means executes retard control for opening the exhaust valve when the crank angle is in a state after bottom dead center, or executes the exhaust gas control when the crank angle is in a state before top dead center. 4. The internal combustion engine having an electromagnetically driven valve mechanism according to claim 3, further comprising retard control / advance control execution means for executing advance control for closing the valve. 5. The reduced-cylinder operation execution means for performing a reduced-cylinder operation in which engine fuel is not injected and ignited during operation of an internal combustion engine for some of the plurality of cylinders. 5. The method according to claim 4, wherein
An internal combustion engine having the electromagnetically driven valve train described in the above. 6. An internal combustion engine having an electromagnetically driven valve mechanism according to claim 5, further comprising torque reduction correction means for performing a torque reduction correction corresponding to a part of the cylinders that do not perform work. organ. 7. A selection for selecting whether to execute the retard control or the advance control or to execute the reduced-cylinder operation in addition to any of these executions in accordance with the operation state of the internal combustion engine. Means for comparing the temperature drop rate of the exhaust gas temperature with a specific predetermined value, and as a result of the comparison by the temperature drop rate comparison means, the rate of reduction of the exhaust gas temperature is determined by the specific rate. If the value is smaller than a predetermined value, the retard control or the advance control is executed. If the rate of decrease in the exhaust gas temperature is equal to or more than the specific value, the execution of the retard control or the advance is performed. The internal combustion engine having an electromagnetically driven valve operating mechanism according to claim 6, wherein the reduced cylinder operation is performed in addition to performing the control.