JP2001303998A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress vibration (pitching) of an engine. SOLUTION: In the case of a straight four-cylinder engine, a first cylinder and a fourth cylinder are divided into an end part cylinder group and a second cylinder and a third cylinder into the second group of a central part cylinder group. The cylinder pressure of the end part cylinder group (the first and the fourth) is controlled to one and the same pressure, the cylinder pressures of the central part cylinder group (the second and the third) controlled to one and the same pressure, and the cylinder pressures of the end part cylinder group (the first and the fourth) controlled to the cylinder pressure lower than the cylinder pressure of the central part cylinder group (the second and the third).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine mounted on an automobile or the like, and more particularly, to an internal combustion engine capable of suppressing vibration by controlling in-cylinder pressure.

[0002]

2. Description of the Related Art In a multi-cylinder internal combustion engine in which a plurality of cylinders are arranged in series, vertical rotational vibration (pitching) of the internal combustion engine may be deteriorated due to variations in in-cylinder pressure and the like.

[0003] Even when the in-cylinder pressure is the same, the downward moment of the cylinder generated during combustion in the cylinder is larger in the cylinder arranged on the outside than in the cylinder arranged in the center. The in-cylinder pressure of the arranged cylinder has a great effect on the pitching of the internal combustion engine.

[0004]

Therefore, for example,
In the case of an in-line four-cylinder internal combustion engine, as shown in FIG. 8, the in-cylinder pressures of the first and fourth cylinders arranged outside are larger than the in-cylinder pressures of the second and third cylinders arranged inside. When this happens, the pitching of the internal combustion engine becomes larger.

[0005] Japanese Patent Application Laid-Open No. 9-53503 discloses that
Based on the combustion pressure information for each cylinder, the air amount for each cylinder is calculated, and fuel corresponding to this air amount is directly supplied into the cylinder.
An internal combustion engine that controls combustion to an intended state is disclosed. However, this publication does not disclose any technique for suppressing the vibration of the internal combustion engine.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems of the prior art, and an object of the present invention is to suppress the vibration of an internal combustion engine by controlling the in-cylinder pressure.
In particular, the purpose is to suppress pitching.

[0007]

The present invention has the following features to attain the object mentioned above. The internal combustion engine according to the present invention has three or more cylinders arranged in series, and is disposed between an end cylinder group disposed at an end of the cylinders and the end cylinder group. When divided into the central cylinder group, the in-cylinder pressure of the end cylinder group is controlled to the same pressure to control the in-cylinder pressure of the central cylinder group to the same pressure, and the in-cylinder pressure of the end cylinder group is controlled. An in-cylinder pressure control means for controlling the in-cylinder pressure to be lower than the in-cylinder pressure of the central cylinder group is provided.

In the internal combustion engine according to the present invention, the in-cylinder pressure control means controls the in-cylinder pressure of the end cylinder group to be lower than the in-cylinder pressure of the central cylinder group. The downward cylinder moment generated at the time of combustion of the end cylinder group is suppressed low, and the vibration (pitting) of the internal combustion engine is suppressed.

In the internal combustion engine according to the present invention, at least one of the intake valve and the exhaust valve provided in the cylinder is an electromagnetically driven valve that can be opened and closed by an electromagnetic force.
The in-cylinder pressure control means may control the in-cylinder pressure by changing the opening / closing timing of the electromagnetically driven valve.

For example, the in-cylinder pressure is controlled by controlling the intake air amount by controlling the closing timing of the intake valve, or by controlling the residual gas amount by controlling the overlap amount between the intake valve and the exhaust valve. can do.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an internal combustion engine having a variable valve mechanism according to the present invention will be described below with reference to FIGS. The embodiments described below are embodiments in which the present invention is applied to a gasoline engine for driving a vehicle as an internal combustion engine.

FIG. 1 and FIG. 2 are views showing the schematic configuration of an internal combustion engine and its intake and exhaust system according to this embodiment. The internal combustion engine shown in FIGS. 1 and 2 is a water-cooled 4-cylinder 4-cycle gasoline engine 1.

The engine 1 includes a cylinder block 1b in which four cylinders 21 and a cooling water passage 1c are formed, and a cylinder head 1 fixed on an upper portion of the cylinder block 1b.
a.

A crankshaft 23 as an engine output shaft is rotatably supported on the cylinder block 1b.
This crankshaft 23 is connected to the connecting rod 1
9 is connected to a piston 22 slidably mounted in each cylinder 21.

Above the piston 22 of each cylinder 21, a combustion chamber 24 surrounded by the top surface of the piston 22 and the wall surface of the cylinder head 1a is formed. The cylinder head 1a has an ignition plug 2 facing the combustion chamber 24 of each cylinder 21.
5 is attached, and the spark plug 25 is
An igniter 25a for applying a drive current to the power supply is electrically connected.

In the cylinder head 1a, each cylinder 2
Two open ends of the intake port 26 and two open ends of the exhaust port 27 are formed at a portion facing one combustion chamber 24. And the cylinder head 1
At a, an intake valve 28 that opens and closes each open end of the intake port 26 and an exhaust valve 29 that opens and closes each open end of the exhaust port 27 are movably mounted.

The cylinder head 1a is provided with an electromagnetic drive mechanism 30 (hereinafter referred to as an intake-side electromagnetic drive mechanism 30) for driving the intake valve 28 forward and backward by using an electromagnetic force generated when an exciting current is applied. The same number of intake valves 28 are provided. Each intake-side electromagnetic drive mechanism 30 is electrically connected to a drive circuit 30a (hereinafter, referred to as an intake-side drive circuit 30a) for applying an exciting current to the intake-side electromagnetic drive 30.

An electromagnetic drive mechanism 31 for driving the exhaust valve 29 forward and backward by using an electromagnetic force generated when an excitation current is applied to the cylinder head 1a (hereinafter referred to as an exhaust-side electromagnetic drive mechanism 31). ) Are provided in the same number as the exhaust valves 29. Each exhaust-side electromagnetic drive mechanism 31 is electrically connected to a drive circuit 31a (hereinafter, referred to as an exhaust-side electromagnetic drive mechanism 31) for applying an exciting current to the exhaust-side electromagnetic drive mechanism 31.

The exhaust-side electromagnetic drive mechanism 31 constitutes a variable valve mechanism in this embodiment. The configurations of the intake-side electromagnetic drive mechanism 30 and the exhaust-side electromagnetic drive mechanism 31 will be described later in detail.

The cylinder head 1a of the engine 1 has 4
An intake manifold 33 having two branch pipes is connected, and the intake port 26 of each cylinder 21 is connected to each branch pipe of the intake manifold 33. In the cylinder head 1a, a fuel injection valve 32 is mounted near a connection portion with the intake manifold 33 with its injection hole facing the intake port 26.

The intake manifold 33 is connected to a surge tank 34 for suppressing pulsation of intake air. The surge tank 34 is connected via an intake pipe 35 to an air cleaner box 36 for removing dust and dirt from the intake air.

An air flow meter 44 for outputting an electric signal corresponding to the mass of air flowing through the intake pipe 35 (mass of intake air) is attached to the intake pipe 35. Downstream of the air flow meter 44 in the intake pipe 35,
A throttle valve 39 for adjusting the flow rate of intake air flowing through the intake pipe 35 is provided.

The throttle valve 39 includes a stepper motor or the like, and a throttle actuator 40 for opening and closing the throttle valve 39 in accordance with the magnitude of the applied power, and a throttle for outputting an electric signal corresponding to the opening of the throttle valve 39. A position sensor 41 and an accelerator position sensor 43 that is mechanically connected to the accelerator pedal 42 and that outputs an electric signal corresponding to the operation amount of the accelerator pedal 42 are attached.

On the other hand, an exhaust manifold 45 having four branch pipes is connected to the cylinder head 1a of the engine 1, and each branch pipe of the exhaust manifold 45 is connected to the exhaust port 27 of each cylinder 21. I have.

The exhaust manifold 45 is provided with the exhaust purification catalyst 4
The casing 46 is connected to a casing 46 that houses the casing 6a. The casing 46 is connected to a muffler (not shown) via an exhaust pipe 47.

Here, as the exhaust purification catalyst 46a, for example, a three-way catalyst, an occlusion reduction type NOx catalyst, a selective reduction type N
An Ox catalyst or a catalyst obtained by appropriately combining these various catalysts can be used. The three-way catalyst refers to HC, C contained in the exhaust gas when the air-fuel ratio of the exhaust gas flowing into the catalyst is a predetermined air-fuel ratio near the stoichiometric air-fuel ratio.
Oxidation-reduction type NOx catalyst is a catalyst that purifies O and NOx. NOx contained in exhaust gas when the air-fuel ratio of exhaust gas flowing into the catalyst is leaner than the stoichiometric air-fuel ratio
The occluded, the air-fuel ratio of the inflowing exhaust gas was absorbed in the time equal to the stoichiometric air-fuel ratio or richer than that NOx released, a catalyst for reducing the N _2, is a selective reduction type NOx catalyst, the oxygen A catalyst that reduces or decomposes NOx in the presence of hydrocarbons in an excess atmosphere.

Here, the air-fuel ratio of the exhaust gas refers to the exhaust passage upstream of the exhaust purification catalyst 46a, the engine combustion chamber,
It means the ratio of the total amount of air supplied to the intake passage or the like to the total amount of fuel (hydrocarbon). Therefore, when no fuel, reducing agent or air is supplied into the exhaust passage upstream of the exhaust purification catalyst 46a, the air-fuel ratio of the exhaust gas matches the air-fuel ratio of the air-fuel mixture supplied into the engine combustion chamber.

The air-fuel ratio of the exhaust gas flowing through the exhaust manifold 45, in other words,
An air-fuel ratio sensor 48 that outputs an electric signal corresponding to the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst 46a is attached.

The engine 1 includes a crankshaft 2
3, a crank position sensor 51 including a timing rotor 51a attached to an end of the engine 3 and an electromagnetic pickup 51b attached to a cylinder block 1b near the timing rotor 51a, and cooling flowing through a cooling water passage 1c formed inside the engine 1. A water temperature sensor 52 attached to the cylinder block 1b to detect the temperature of water is provided.

Here, the aforementioned intake side electromagnetic drive mechanism 30
The exhaust-side electromagnetic drive mechanism 31 will be described. still,
Since the intake-side electromagnetic drive mechanism 30 and the exhaust-side electromagnetic drive mechanism 31 have the same configuration, the intake-side electromagnetic drive mechanism 30 will be described as an example, and the description of the exhaust-side electromagnetic drive mechanism 31 will be omitted.

FIG. 3 is a sectional view showing the structure of the intake-side electromagnetic drive mechanism 30. In FIG. 3, the cylinder head 1a of the engine 1 includes a lower head 10 fixed to the upper surface of the cylinder block 1b, and an upper head 11 provided on the lower head 10.

The lower head 10 is provided with the above-described two intake ports 26 for each cylinder 21, and the above-described intake valve 2 is provided at the open end of each intake port 26 on the combustion chamber 24 side.
The valve seat 12 on which the eighth valve body 28a is seated is provided.

The lower head 10 is formed with a through hole having a circular cross section penetrating from the inner wall surface of each intake port 26 to the upper surface of the lower head 10, and a cylindrical valve guide 13 is inserted and fixed in the through hole. . In the valve guide 13,
A valve shaft 28b of the intake valve 28 extends through the valve so that it can move forward and backward in the axial direction.

A core mounting hole 14 having a circular cross section is provided in the upper head 11 concentrically with the valve guide 13.
The core mounting hole 14 has a large-diameter portion 14 b having a large hole diameter at a portion facing the lower head 10.
a small-diameter portion 14 having a smaller hole diameter than the large-diameter portion 14b above b
a are connected.

An annular first core 301 and a second core 302 made of a soft magnetic material are fitted in the small diameter portion 14a in series in the axial direction with a predetermined gap 303 therebetween. At the upper end of the first core 301 and the lower end of the second core 302,
A flange 301a or a flange 302a is formed.
2 are inserted into the core mounting holes 14 from below, and the first core 301 is formed by the flange 301a and the flange 302a contacting the upper edge or the lower edge of the small diameter portion 14a.
And the second core 302 is positioned, and the gap 303
Is maintained at a predetermined distance.

Above the first core 301, a cylindrical upper cap 305 is attached. The upper cap 305 has a flange 305 formed at the lower end thereof.
a is fixed to the upper surface of the upper head 11 by passing a bolt 304 through it. Here, the lower end of the upper cap 305 including the flange portion 305a is fixed in a state of being in contact with the peripheral edge of the upper surface of the first core 301, whereby the first core 301 is fixed to the upper head 11.

On the other hand, a lower cap 307 made of an annular body having an outer diameter substantially the same as that of the large-diameter portion 14b of the core mounting hole 14 is mounted below the second core 302. The lower cap 307 is fixed by a bolt 306 to a step surface formed at a boundary between the small diameter portion 14a and the large diameter portion 14b. Here, the lower cap 307 is connected to the second core 30.
The second core 302 is fixed to the upper head 11 in a state in which it abuts on the lower peripheral edge of the second core 302.

A first electromagnetic coil 308 is mounted on a groove formed on the end face of the first core 301 on the gap 303 side, and a groove formed on an end face of the second core 302 on the gap 303 side is provided. The second electromagnetic coil 309 is mounted. The first electromagnetic coil 308 and the second electromagnetic coil 309 are disposed to face each other with a gap 303 therebetween, and the first and second electromagnetic coils 308 and 309 are electrically connected to the above-described intake side drive circuit 30a. Connected.

An armature 311 made of a disk-shaped soft magnetic material having an outer diameter smaller than the inner diameter of the gap 303 is arranged in the gap 303. An armature shaft 310 is fixed through the center of the armature 311. The upper half of this armature shaft 310 is the first
The upper portion of the core 301 penetrates through the hollow portion of the core 301 so as to project into the upper cap 305, and the lower half of the core 301 penetrates through the hollow portion of the second core 302 so that the lower end projects into the large-diameter portion 14b. The first core 301 and the second core 302 are held movably in the axial direction.

A disk-shaped retainer 312 is fixed to the upper end of the armature shaft 310 protruding into the upper cap 305, and an adjust bolt 313 is screwed into an upper opening of the upper cap 305. . These applique retainer 312 and adjust bolt 3
An upper spring 314 is sandwiched between the adjustment bolt 313 and the adjustment bolt 313 via a spring seat 315. The upper spring 314 causes the armature shaft 310 and the armature 311 to have a large diameter portion 14b (That is, downward in FIG. 3).

On the other hand, the upper end of the valve shaft 28b of the intake valve 28 abuts on the lower end of the armature shaft 310 protruding into the large diameter portion 14b. A disc-shaped lower retainer 29c is fixed to the upper end of the valve shaft 28b,
A lower spring 316 is sandwiched between the lower retainer 29c and the lower head 10, and the lower spring 316 urges the intake valve 28 in a valve closing direction (that is, upward in FIG. 3). As a result, the upper end of the valve shaft 28b of the intake valve 28 abuts on the lower end of the armature shaft 310, and the armature shaft 310 and the armature 31
1 is urged in a direction away from the large-diameter portion 14b of the core mounting hole 14 (that is, upward in FIG. 3).

In the intake-side electromagnetic drive mechanism 30 configured as described above, when the exciting current is not applied from the intake-side drive circuit 30a to the first electromagnetic coil 308 and the second electromagnetic coil 309, the armature is not operated. 311, an upper spring 314 moves the armature 311 downward (ie,
A force that urges the armature 311 upward (that is, a direction that closes the intake valve 28) by the lower spring 316 and a force that urges the armature 311 upward (that is, a direction that closes the intake valve 28) act on the urging force. At this position, the armature 311 is elastically supported and is maintained in a neutral state.

The biasing force of the upper spring 314 and the lower spring 316 is set such that the neutral position of the armature 311 coincides with the intermediate position between the first core 301 and the second core 302 in the gap 303. When the neutral position of the armature 311 is deviated from the above-described intermediate position due to an initial tolerance of components, aging, etc., it is possible to adjust the neutral position of the armature 311 with the adjust bolt 313 so as to match the above-described intermediate position. Has become.

The length of the armature shaft 310 and the valve shaft 28b in the axial direction is determined by the distance between the armature 311 and the gap 30.
3, the valve body 28a is set to an intermediate position between the fully open side displacement end and the fully closed side displacement end (hereinafter, referred to as a middle open position).

In the intake-side electromagnetic drive mechanism 30 configured as described above, when an excitation current is applied to the first electromagnetic coil 308 from the intake-side drive circuit 30a, the first core 30
1 between the first electromagnetic coil 308 and the armature 311, an electromagnetic force is generated in a direction to displace the armature 311 toward the first core 301, and the second electromagnetic force is generated from the intake side drive circuit 30 a to the second side.
When an exciting current is applied to the electromagnetic coil 309 of
An armature 311 is provided between the second core 302, the second electromagnetic coil 309, and the armature 311.
An electromagnetic force is generated in the direction of displacing to the side.

Therefore, the intake side electromagnetic drive mechanism 30
In this case, the armature 311 and the armature shaft 310 move forward and backward by alternately applying the exciting current from the intake side drive circuit 30a to the first electromagnetic coil 308 and the second electromagnetic coil 309, and the valve is synchronized with the armature 311 and the armature shaft 310. The shaft 28b is driven forward and backward, and as a result, the valve body 28a is driven to open and close.

At this time, the first electromagnetic coil 308 and the second
By changing the timing of applying the exciting current to the electromagnetic coil 309 and the magnitude of the exciting current, the intake valve 28
Opening / closing timing can be controlled.

The intake-side electromagnetic drive mechanism 30 includes:
Valve lift sensor 317 for detecting displacement of intake valve 28
Is attached. This valve lift sensor 317
Is composed of a disk-shaped target 317a attached to the upper surface of the applicator 312, and a gap sensor 317b attached to a part of the adjustment bolt 313 facing the above-mentioned retainer 312.

In the valve lift sensor 317 thus configured, the target 317a is displaced integrally with the armature 311 and the gap sensor 317b outputs an electric signal corresponding to the distance between the gap sensor 317b and the target 317a.

At this time, the output signal value of the gap sensor 317b when the armature 311 is in the neutral state is stored in advance, and the deviation between the output signal value and the current output signal value of the gap sensor 317b is calculated. Thereby, the displacement of the armature 311 and the intake valve 28 can be specified.

The engine 1 has an electronic control unit (Electronic Control Unit) for controlling the operation state of the engine 1.
A control unit (ECU) 20 is also provided. ECU2
0 is a digital computer, as shown in FIG.
(Central processor unit) 401, ROM (read only memory) 402, RAM (random access memory) 403, input port 405, output port 406
A / A connected to the input port 405
A D converter (A / D) 407 is provided.

An analog signal output from the throttle position sensor 41, the accelerator cell position sensor 43, the air flow meter 44, the air-fuel ratio sensor 48, the water temperature sensor 52, the valve lift sensor 317, and the like is input to the input port 405 of the ECU 20 by A / D. The signal is converted into a digital signal by the converter 407 and input. The digital signal output from the crank position sensor 51 is directly input to the input port 405 of the ECU 20.

The output port 406 of the ECU 20 includes the igniter 25a, the intake side drive circuit 30a, and the exhaust side drive circuit 3
1a, fuel injection valve 32, throttle actuator 4
0 and the like.

The ROM 402 of the ECU 20 has a fuel injection amount control routine for determining the fuel injection amount, a fuel injection timing control routine for determining the fuel injection timing, and an ignition timing of the ignition plug 25 of each cylinder 21. , The throttle opening control routine for determining the opening of the throttle valve 39, the intake valve opening / closing timing control for determining the opening / closing timing of the intake valve 28, and the opening / closing timing of the exhaust valve 29. Valve opening / closing timing control routine for determining the amount of excitation current to be applied to the intake-side electromagnetic drive mechanism 30, and determining the amount of excitation current to be applied to the exhaust-side electromagnetic drive mechanism 31 In this embodiment, in addition to application programs such as an exhaust-side excitation current amount control routine for Stores pressure control routine.

The ROM 402 of the ECU 20 stores various control maps in addition to the above-described application programs. For example, a fuel injection amount control map showing the relationship between the operating state of the engine 1 and the fuel injection amount, a fuel injection timing control map showing the relationship between the operating state of the engine 1 and the fuel injection timing, the operating state of the engine 1 and each ignition Stopper 2
5, a throttle opening control map showing the relationship between the operating state of the engine 1 and the opening of the throttle valve 39, the operating state of the engine 1 and the opening / closing timing of the intake valve 28. , An exhaust valve opening / closing timing control map showing the relationship between the operating state of the engine 1 and the opening / closing timing of the exhaust valve 29, the operating state of the engine 1 and the intake electromagnetic drive mechanism 30 and the exhaust side An excitation current amount control map or the like showing a relationship with an excitation current amount to be applied to the electromagnetic drive mechanism 31 is shown.

The RAM 403 stores output signals of each sensor and C
The calculation result of the PU 401 is stored. The calculation result is:
For example, it is an engine speed calculated based on an output signal of the crank position sensor 51 or the like. Various data stored in the RAM 403 is rewritten to the latest data every time the crank position sensor 51 outputs a signal.

The backup RAM 45 is a non-volatile memory that retains data even after the operation of the engine 1 is stopped, and stores learning values related to various controls. CPU 401
Operates according to an application program stored in the ROM 402 to execute fuel injection control, ignition control, throttle control, in-cylinder pressure control, and the like.

At this time, the CPU 401 determines the operating state of the engine 1 using the output signal values of the crank position sensor 51, the accelerator position sensor 43, the air flow meter 44, and the like as parameters, and various types of operation are performed in accordance with the determined operating state. Execute control.

For example, when the CPU 401 determines that the operating state of the engine 1 is in the low-to-medium load operating range, the CPU 401 performs lean combustion operation with an air-fuel mixture in an excess oxygen state (air-fuel mixture with a lean air-fuel ratio). The throttle opening, fuel injection amount, opening / closing timing of the intake valve 28, opening / closing timing of the exhaust valve 29, and ignition timing are controlled.

If it is determined that the operation state of the engine 1 is in the high load operation range, the CPU 401 determines the throttle opening, fuel consumption, and the like in order to realize stoichiometric operation with a stoichiometric mixture (stoichiometric mixture). Injection amount, intake valve 28
, The opening / closing timing of the exhaust valve 29, and the ignition timing.

Next, the in-cylinder pressure control in the engine 1 will be described. The ignition order in the engine 1 is in the order of the first cylinder → the third cylinder → the fourth cylinder → the second cylinder.

In the engine 1, in-cylinder pressure is controlled as described below in order to suppress vibration (pitting) of the engine 1 due to a downward moment of the cylinder generated during combustion in the cylinder. First, in performing the in-cylinder pressure control, the four cylinders are divided into two groups. That is, the first cylinder and the fourth cylinder arranged outside of the four cylinders are set as end cylinder groups,
The second and third cylinders arranged between them are divided into two groups as a central cylinder group.

Then, as shown in FIG. 5, the in-cylinder pressures of the first and fourth cylinders in the end cylinder group are controlled to be the same, and the second and third cylinders in the central cylinder group are controlled. The in-cylinder pressure of the cylinders is controlled to be the same pressure, and the in-cylinder pressure of the end cylinder group is controlled to be lower than the in-cylinder pressure of the central cylinder group.

When the in-cylinder pressure of each cylinder is controlled as described above,
Since the downward moment of the cylinder generated when the first or fourth cylinder disposed outside is combusted, the vertical vibration (pitting) of the engine 1 can be suppressed low.

Further, the in-cylinder pressures of the cylinders of the end cylinder group (No. 1 and No. 4) are set to the same pressure, and the cylinders of the middle cylinder group (No. 2 and No. 3) are set.
Are controlled so as to be the same pressure, so that the vibration can be made symmetrical and unbiased. FIG.
FIG. 5 is a diagram showing a change in the in-cylinder pressure rearranged in the order of ignition.

In this embodiment, the in-cylinder pressure of each cylinder is controlled as described above by independently controlling the opening / closing timing of the intake valve 28 and the exhaust valve 29 for each cylinder. Alternatively, the combustion pattern is made uniform for each central cylinder group.

For example, the amount of intake air can be changed by changing the closing timing of the intake valve 28, thereby changing the in-cylinder pressure, or the residual amount can be changed by changing the amount of overlap between the intake valve 28 and the exhaust valve 29. It is possible to change the amount of gas and thereby change the in-cylinder pressure, and it is also possible to change both of them simultaneously to change the in-cylinder pressure.

As a more specific control method, the engine operating state (engine speed and engine load) and the opening / closing timing of the intake valves 28 and exhaust valves 29 of the cylinders (No. 1 and No. 4) of the end cylinder group are determined. A low-pressure control intake valve opening / closing timing map and a low-pressure control exhaust valve opening / closing timing map indicating the relationship;
A high-pressure control intake valve opening / closing timing map and a high-pressure control exhaust valve opening / closing timing map showing the relationship between the engine operating state and the opening / closing timing of the intake valves 28 and exhaust valves 29 of the cylinders (No. 2 and No. 3) in the central cylinder group. Is stored in the ROM 402 of the ECU 20 in advance, and a method of determining the opening / closing timing of the intake valve 28 and the exhaust valve 29 with reference to these maps can be exemplified.

Next, the in-cylinder pressure control in this embodiment will be described with reference to the flowchart of FIG. C
When performing the in-cylinder pressure control, the PU 401 executes an in-cylinder pressure control routine shown in FIG. This in-cylinder pressure control routine is stored in the ROM 402 of the ECU 20 in advance, and is repeatedly executed by the CPU 401 at regular intervals.

<Step 101> First, the CPU 401
Performs cylinder discrimination in step 101. Since the cylinder discriminating method is a well-known technique, the description is omitted here.

<Step 102> Next, the CPU 401
Proceeds to step 102, and determines whether the cylinder determined in step 101 is the first cylinder or the fourth cylinder. That is, it is determined whether the cylinder determined in step 101 belongs to the end cylinder group.

<Step 103> If the determination in step 102 is affirmative, the CPU 401 proceeds to step 1
03, referring to the low-pressure control intake valve opening / closing timing map and the low-pressure control exhaust valve opening / closing timing map, determine the intake valve opening / closing timing and the exhaust valve opening / closing timing according to the engine operating state. The intake-side electromagnetic drive mechanism 30 is opened and closed so that the intake valve 28 and the exhaust valve 29 are opened and closed.
The operation of the exhaust-side electromagnetic drive mechanism 31 is controlled to execute in-cylinder low-pressure control.

<Step 104> On the other hand, step 102
If a negative determination is made in step 101, the cylinder determined in step 101 belongs to the central cylinder group (the second cylinder or the third cylinder), and the CPU 401 proceeds to step 104 and executes the high-pressure control intake. With reference to the valve opening / closing timing map and the high-pressure control exhaust valve opening / closing timing map, the intake valve opening / closing timing and the exhaust valve opening / closing timing according to the engine operating state are obtained. As shown in FIG.
0 and the exhaust-side electromagnetic drive mechanism 31 are controlled to perform in-cylinder high-pressure control.

As described above, when the CPU 401 executes the in-cylinder pressure control routine, the in-cylinder pressure control means according to the present invention is realized. It is also possible to provide an in-cylinder pressure sensor for detecting the in-cylinder pressure in each cylinder, and perform feedback control of the opening / closing timing of the intake valve 28 or the exhaust valve 29 based on the in-cylinder pressure detected by each in-cylinder pressure sensor to make correction. It is possible.

When the in-cylinder pressure is controlled in this manner, the combustion patterns can be made uniform, so that the exhaust emission does not vary and the air-fuel ratio control for each cylinder can be performed more precisely.

[0076]

According to the internal combustion engine of the present invention, there are provided three or more cylinders arranged in series, and, among these cylinders, an end cylinder group arranged at an end portion and the end cylinder group When divided into the central cylinder group disposed between the groups, the in-cylinder pressure of the end cylinder group is controlled to the same pressure, and the in-cylinder pressure of the central cylinder group is controlled to the same pressure. The provision of the in-cylinder pressure control means for controlling the in-cylinder pressure of the partial cylinder group to be lower than the in-cylinder pressure of the central cylinder group has an excellent effect of suppressing the vibration of the internal combustion engine. You.

[Brief description of the drawings]

FIG. 1 is a diagram (part 1) illustrating a schematic configuration in an embodiment of an internal combustion engine according to the present invention.

FIG. 2 is a diagram (part 2) illustrating a schematic configuration in an embodiment of the internal combustion engine according to the present invention.

FIG. 3 is a diagram showing an internal configuration of an intake-side electromagnetic drive mechanism in the embodiment.

FIG. 4 is a block diagram showing an internal configuration of an ECU according to the embodiment.

FIG. 5 is a diagram showing the in-cylinder pressure of each cylinder in the embodiment.

FIG. 6 is a diagram showing in-cylinder pressure of each cylinder in the order of ignition in the embodiment.

FIG. 7 is a flowchart showing a cylinder pressure control routine in the embodiment.

FIG. 8 is a diagram showing an example of a conventional in-cylinder pressure of each cylinder.

[Explanation of symbols]

 Reference Signs List 1 engine (internal combustion engine) 20 ECU 21 cylinder 22 piston 28 intake valve 29 exhaust valve 30 intake-side electromagnetic drive mechanism 31 exhaust-side electromagnetic drive mechanism 30a intake-side drive circuit 31a exhaust-side drive circuit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshihiro Iwashita 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Kazuhiko 1 Toyota Motor Town Toyota City, Aichi Prefecture Inside Toyota Motor Corporation ( 72) Inventor Shoji Katsumada 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Co., Ltd. (72) Inventor Keiji Yoeda 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Automobile Co., Ltd. (72) Inventor Tomomi Yamada 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 3G018 AA06 AB09 AB16 BA38 CA12 DA24 DA36 DA38 DA41 DA66 DA83 EA02 EA11 EA22 EA35 FA07 FA09 GA32 3G092 AA01 AA11 AA12 AA13 DA01 DA02 DA07 DA12 DC03 DG09 FA14 H A01Z HA06Z HC01Z HD05Z HE01Z HE03Z HE08Z HF08Z

Claims (2)

[Claims] 1. A cylinder having three or more cylinders arranged in series, and an end cylinder group disposed at an end of the cylinders and a central cylinder disposed between the end cylinder groups. When divided into groups, while controlling the in-cylinder pressure of the end cylinder group to the same pressure and controlling the in-cylinder pressure of the central cylinder group to the same pressure,
An internal combustion engine comprising an in-cylinder pressure control means for controlling the in-cylinder pressure of the end cylinder group to be lower than the in-cylinder pressure of the central cylinder group. 2. An electromagnetically driven valve that is opened and closed by an electromagnetic force at least one of an intake valve and an exhaust valve provided in the cylinder, and the in-cylinder pressure control means changes an opening and closing timing of the electromagnetically driven valve. 2. The internal combustion engine according to claim 1, wherein the in-cylinder pressure is controlled by the control.