JPH07279698A - Internal combustion engine - Google Patents

Abstract

PURPOSE:To enable the partial cylinder operation without using any an intake air cutoff valve, so as to decrease pumping loss of the stop cylinder by opening an exhaust valve as well as controlling an intake air control valve of a first cylinder group to be stopped in stopping of the partial cylinder so that the valve opening time may be zero in low loading. CONSTITUTION:In the partial cylinder operation, an intake valve is opened and closed similar to in the full cylinder operation, however intake control valves 5a, 5d on the stop cylinders 3a, 3d sides, out of four intake control valves are controlled so that the valve opening time may be zero, and new air flow is shut off. Moreover, electrification of an air bypass amount control valve 6V is shut off. That is, new air introducing into combustion chambers 3a, 3d is eliminated, the combustion operation is stopped. While, since a negative pressure atmospheric pressure passage switching valve 16 is electrified, negative pressure is transmitted to an exhaust recirculation valve 9, and a sluice valve in the exhaust recirculation valve 9 is released. Accordingly, exhaust gas discharged from the combustion chambers 3b, 3c of the operating cylinders is partially introduced into an exhaust recirculation passage 10 and returned downward from the intake control valves 5a, 5d.

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, and more particularly to an internal combustion engine capable of switching between partial cylinder operation and full cylinder operation.

[0002]

2. Description of the Related Art Engines that perform partial cylinder operation at low load are known, and various methods have been devised to improve their efficiency. For example, JP-A-57-181947
There is one disclosed in the publication. In the internal combustion engine of the publication, an intake cutoff valve is arranged in an intake passage of a deactivated cylinder, an exhaust gas recirculation passage outlet is arranged downstream of the intake cutoff valve, and the intake cutoff valve is operated during operation of a low load partial cylinder. The valve is closed and exhaust gas is circulated downstream of the intake cutoff valve to reduce pumping loss in the idle cylinder.

[0003]

However, in the intake system of Japanese Patent Laid-Open No. 57-181947, the pumping loss of the idle cylinder is reduced during the partial cylinder operation, but the partial throttle valve is throttled because the pumping loss is reduced. There is a problem that it is not possible to reduce the pumping loss of the cylinder operating during cylinder operation. In view of the above problems, it is an object of the present invention to provide an internal combustion engine that can reduce pumping loss of cylinders that are operating during partial cylinder operation.

[0004]

According to the first aspect of the present invention, the intake control valve is provided in the intake passage of each cylinder, and the intake control means controls the opening time of the intake control valve. In the internal combustion engine, the cylinders are divided into a first cylinder group that is inactive during partial cylinder operation and a second cylinder group that is active during partial cylinder operation, and the first cylinder group includes a downstream side of the intake control valve and an exhaust passage. An exhaust gas recirculation valve is provided in the exhaust gas recirculation passage, which controls the opening time of the intake control valve of the first cylinder group to zero, opens the exhaust gas recirculation valve, and injects fuel when the load is low. To stop the operation, operate only the second cylinder group to perform partial cylinder operation, and control the intake control valves of the first cylinder group and the second cylinder group at equal valve opening times during high load. In addition, the exhaust gas recirculation valve is closed to operate all cylinders. An internal combustion engine and is provided.
According to claim 2, in switching between the all cylinder operation and the partial cylinder operation, the opening time of the intake control valve of the second cylinder group in the all cylinder operation is set shorter than that in the partial cylinder operation. An internal combustion engine characterized by the above is provided. According to claim 3, further, immediately after switching from the partial cylinder operation to the all cylinder operation, the intake control valve of the first cylinder group is set to a predetermined valve opening time during the all cylinder operation, and the intake air of the second cylinder group in the previous period is set. The control valve opening time is gradually shortened until the predetermined valve opening time is reached, and the fuel injection amount of the first cylinder group is gradually increased to a predetermined value during all-cylinder operation. The internal combustion engine according to claim 2, wherein the injection amount is gradually reduced to a predetermined value during all-cylinder operation.

[0005]

According to the first aspect of the present invention, the pumping loss is reduced because the intake air is shut off by the intake timing control means and the exhaust gas recirculation valve is opened to recirculate the exhaust gas in the idle cylinder during the partial cylinder operation. In the operating cylinder, the intake timing control means controls the overlap period of the intake control valve and the intake valve to reduce pumping loss. Further, during all cylinder operation, the intake timing control means controls the overlap period of the intake control valve and the intake valve to reduce pumping loss. Further, in switching between the all-cylinder operation and the partial-cylinder operation as in claim 2, by making the opening time of the intake control valve in the all-cylinder operation shorter than in the partial-cylinder operation, the all-cylinder operation and the partial-cylinder operation are performed. The difference in the output of the engine before and after the operation switching is reduced, and the shock is reduced.
Immediately after switching from the partial cylinder operation to the all cylinder operation as in claim 3, the opening time of the intake control valve of the cylinder group that is always operating is shortened stepwise until it reaches the opening time during the all cylinder operation. The amount of fuel injection is also reduced, the opening time of the control valve on the deactivated cylinder side is set to the opening time for all cylinder operation, and the fuel injection amount is gradually increased to smooth the torque while keeping the air-fuel ratio constant. Therefore, the partial cylinder operation can be smoothly switched to the all cylinder operation.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram schematically showing the configuration of the first embodiment of the present invention. Reference numeral 1 is a throttle valve, but the throttle valve 1 obtains a negative pressure for operating devices controlled by a negative pressure, or the intake control valve fails to close so that more air than necessary is sucked into the engine. This is to prevent runaway, and as shown in FIG. 2, it is fully opened after the accelerator pedal is depressed to a certain extent or more, and is basically unrelated to the control of the intake air amount.

2 is a surge tank, 3a, 3b, 3c, 3
d is the combustion chamber of each cylinder. Here, the combustion chambers 3a and 3d
Is provided in the first cylinder group, and the combustion chambers 3b and 3c are provided in the second cylinder group.
Surge tank 2 and combustion chambers 3a, 3b, 3c, 3 of each cylinder
d is connected by intake passages 4a, 4b, 4c, 4d, and intake control valves 5a, 5b, and
5c and 5d are provided. 6a, 6b, 6c, 6d
Is an air bypass passage, and each is a surge tank 2
To introduce a small amount of air into the intake passages 4a, 4b, 4c, 4d immediately before the combustion chambers 3a, 3b, 3c, 3d of each cylinder by bypassing the intake control valves 5a, 5b, 5c, 5d. . Among them, 6a and 6d are gathered together on the upstream side, and an air bypass amount control valve 6v is arranged at the gathering portion.

Reference numerals 7a, 7b, 7c and 7d are fuel injection valves. Reference numerals 8a, 8b, 8c, and 8d denote exhaust passages of the cylinders, and the exhaust passages are grouped together on the downstream side. Reference numeral 9 is an exhaust gas recirculation valve, 10 is an exhaust gas recirculation passage that connects the exhaust gas passage 8a and the exhaust gas recirculation valve 9, and 11a is an exhaust gas recirculation valve 9 and the intake air passage 4
Reference numeral 11d is an exhaust gas recirculation passage communicating with the downstream side of the intake control valve 5a, and 11d is an exhaust gas recirculation passage communicating with the exhaust gas recirculation valve 9 and the intake control valve 5d downstream side of the intake passage 4d.
Reference numeral 12 is a cooler for lowering the temperature of the exhaust gas to be recirculated.

The exhaust gas recirculation valve 9 adjusts the amount of exhaust gas recirculated by moving the position of the internal valve by negative pressure. The negative pressure is temporarily stored in the negative pressure reserve tank 14 from the surge tank 2 through the negative pressure passage 13 and then transmitted to the exhaust gas recirculation valve 9 through the negative pressure passage 15, but in the middle of the negative pressure passage 15. A negative pressure / atmospheric pressure passage switching valve 16 is interposed, and the exhaust gas recirculation valve 9 is opened / closed by connecting / disconnecting electricity to the negative pressure / atmospheric pressure passage switching valve 16. Reference numeral 17 denotes an electronic control unit (hereinafter referred to as an ECU), which serves as intake time control means according to claim 1, and the intake control valve 5a according to operating conditions.
In addition to controlling the valve opening time of 5b, 5c, 5d, the control of the valve opening amount of the air bypass amount control valve 6v, the negative pressure atmospheric pressure passage switching valve 16, and the fuel injection of the fuel injection valves 7a, 7b, 7c, 7d. It controls the injection amount and ignition timing.

Next, the operation of the embodiment of the present invention constructed as above will be described. First, the full cylinder operating range and the partial cylinder operating range will be described. FIG. 3 shows the entire cylinder operating region and the partial cylinder operating region on a coordinate plane in which the horizontal axis represents the engine speed and the vertical axis represents the throttle opening. The portion indicated by A in the figure is the entire cylinder operating region. And B
The portion indicated by is the partial cylinder operating region. Switching between full cylinder operation and partial cylinder operation is basically performed by controlling the opening time of the intake control valve, and fuel injection control is added thereto.

FIG. 4 is a diagram for explaining the operation of the intake control valve. In the figure, the broken line indicates the opening period of the intake control valve, and the solid line indicates the intake valve. Is the valve opening period. In the present embodiment, since the intake valve is not provided with a variable device, the opening period of the intake valve is constant and does not change. On the other hand, in the intake control valve, the opening start timing and the closing end timing can be arbitrarily changed, so that the valve opening period can be freely set. Then, since fresh air is actually introduced only during the period in which the intake control valve opening period and the intake valve opening period overlap, if the overlapping period is set to 0 (zero), No fresh air is introduced and partial cylinder operation can be performed. Further, it is possible to reduce the pumping loss by delaying the valve closing timing for the operating cylinders in the all cylinder operation or in the partial cylinder operation.

In the partial cylinder operation, the intake valve is opened and closed as in the full cylinder operation, but 5a and 5 of the four intake control valves are used.
d has the valve opening time set to 0 (zero), and the intake passages 4a and 4d
The inflow of fresh air passing through is also cut off, and since the energization of the air bypass amount control valve 6v is cut off, the inflow of fresh air passing through 6a and 6d is also cut off. Therefore, no fresh air is introduced into the combustion chambers 3a and 3d, and no fuel is injected into these two combustion chambers and combustion is not performed. Further, since the negative pressure / atmospheric pressure passage switching valve 16 is energized, a negative pressure is transmitted to the exhaust gas recirculation valve 9, and the sluice valve inside the exhaust gas recirculation valve 9 is released. Therefore, the combustion chamber 3 of the operating cylinder
Part of the exhaust gas discharged from b and 3c is introduced into the exhaust gas recirculation passage 10 and cooled to an appropriate temperature by the cooler 12, and then passes through the branched exhaust gas recirculation passages 11a and 11d to the intake control valves 5a and 5d. Is returned downstream.

As a result, the exhaust gas having a pressure higher than the atmospheric pressure is introduced into the combustion chambers 3a and 3d of the idle cylinder which does not perform combustion, so that the pumping loss is small. On the other hand, the intake control valve of the cylinder that continues to operate is opened so that a required amount of air is sucked in, but as described above, there is almost no throttling by the throttle and the pumping loss is small.

In all-cylinder operation, the intake control valves 5a, 5b,
5c and 5d are evenly controlled according to the load, and most of the fresh air drawn in from the surge tank 2 to the intake passages 4a, 4b,
Although it is introduced through 4c and 4d, the pumping loss is small because there is almost no throttle diaphragm as described above. The air bypass amount control valve 6v is energized and opened, and a part of the fresh air inside the surge tank 2 passes through the air bypass passages 6a, 6b, 6c, 6d, and the combustion chambers 3a, 3b of the respective cylinders. Intake passages 4a, 4 immediately before 3c, 3d
It is directly introduced into b, 4c and 4d to generate turbulence in the combustion chamber to improve combustion. At this time, the negative pressure / atmospheric pressure passage switching valve 16 is not energized, is kept at atmospheric pressure, and is closed by the function of the return spring in the exhaust gas recirculation valve 9, so that the exhaust gas is not recirculated.

The above is the structure and operation of the portion according to claim 1 of the present embodiment, which not only makes it possible to reduce the pumping loss of the idle cylinder during partial cylinder operation, but also the pumping loss of the operating cylinder. Can be reduced, and pumping loss during all cylinder operation can be reduced. Further, during all cylinder operation, the air bypass amount control valve 6
When v is energized and opened, a part of the fresh air inside the surge tank 2 is directly introduced into the intake passage immediately before the combustion chamber of each cylinder, so that turbulence is generated in the combustion chamber and combustion is improved. Is performed.

FIG. 5 shows the valve opening time of the intake control valve and the fuel injection time when switching from the full cylinder operation to the partial cylinder operation. In the figure, the second cylinder group is always operating. Is indicated by a solid line, and the first cylinder group that is deactivated during partial cylinder operation is indicated by a broken line. In FIG. 5, 2
There are two characteristics. The first feature is the second that is always operating
The opening time of the intake control valve of the cylinder group during all-cylinder operation is shorter than the opening time during partial-cylinder operation. The second feature is that when the partial-cylinder operation is switched to the all-cylinder operation. This means that the valve opening time of the second cylinder group is gradually reduced from the time of partial cylinder operation to reach the valve opening time of all cylinder operation.

The first feature corresponds to claim 2 of the present invention, and the second feature corresponds to claim 3. First, the first feature will be described. In an engine that performs partial cylinder operation, it is important to suppress the shock when switching from partial cylinder operation to full cylinder operation, or conversely, from full cylinder operation to partial cylinder operation. This is the output of all cylinder operation in the region where partial cylinder operation is performed as shown in FIG.
It is obtained by making the output of the partial cylinder operation the same or equal.

In order to obtain the same output, the engines need to do the same work, and the total amount of air and fuel required for that purpose is basically about the same. Therefore, if partial cylinder operation is performed with half the number of cylinders during full cylinder operation as in the present embodiment, the intake air amount of each cylinder during partial cylinder operation is basically It is about twice the amount of intake air for each cylinder. Actually, there is a difference in combustion efficiency when the intake air amount is large and small, and a friction loss difference between the partial cylinder operation and the all cylinder operation. In order to suppress the shock when switching between operation and full cylinder operation, it is necessary to make the intake air amount of the operating cylinder during partial cylinder operation larger than the intake air amount of each cylinder during full cylinder operation. . For the above reason, the valve opening time of the intake control valve of the second cylinder group, which is always operating, during the full cylinder operation is set shorter than the valve opening time during the partial cylinder operation. The output of the engine before and after the switching of the partial cylinder operation is made equal to suppress the occurrence of shock.

Next, the second feature will be described. During partial cylinder operation, exhaust gas is recirculated downstream of the intake control valve of the deactivated cylinder, and the intake passage between the intake control valve and the intake valve is filled with exhaust gas. Therefore, immediately after switching from the partial cylinder operation to the all cylinder operation, the exhaust gas that has filled the intake passage between the intake control valve and the intake valve is introduced into the combustion chamber of the cylinder that has been deactivated. Since this exhaust gas acts to suppress combustion, it is not possible to immediately obtain the same output as that of the cylinder that always operates. Therefore, at the time of switching, the exhaust recirculation gas in the deactivated cylinders is exhausted, and the opening time of the intake control valve of the constantly operating cylinders is shortened stepwise until an output equivalent to that of the always operating cylinder is obtained. The same applies to fuel. By the above, the switching from the partial cylinder operation to the all cylinder operation is smoothly performed.

FIG. 6 shows the valve opening time of the intake control valve and the fuel injection time when switching from the full cylinder operation to the partial cylinder operation. When shifting from the full cylinder operation to the partial cylinder operation, FIG. Immediately, the opening time of the intake control valve and the fuel injection amount are set to the always operating cylinder condition during the partial cylinder operation.

FIG. 8 is a diagram schematically showing the configuration of the second embodiment of the present invention, which is applied to a 6-cylinder internal combustion engine. Portions having the same functions as those in FIG. 1 are designated by the same reference numerals. 18, 19 and 20 are catalytic converters,
Nos. 8 and 19 have a short distance from the exhaust port and are particularly effective in reducing emissions at the time of starting. In the second embodiment,
The exhaust system is divided into two groups, one for the idle cylinder group and the one for the constantly operating cylinder group. Therefore, the exhaust gas of the constantly operating cylinder group does not easily enter the idle cylinder group side, and the gas temperature drops, so that a cooler for cooling the recirculation gas is unnecessary.
Further, since the exhaust gas of the constantly operating cylinder group does not easily enter the idle cylinder group side, adhesion of deposits to the intake control valve, the intake valve, the intake passage, etc. is reduced. Furthermore, if the fuel in the partial cylinder group is cut when switching to partial cylinder operation, the exhaust gas recirculation valve is opened, and the intake control valve is fully closed, the air that has blown through without recirculating will recirculate in the exhaust gas recirculation passage,
After all, deposits on the intake control valve, intake valve, intake passage, etc. are reduced. When the recirculation gas becomes insufficient, it may be considered that the intake control valve is slightly opened to supply air during the intake stroke of the group of cylinders operating in the partial cylinder so that the air-fuel ratio does not become rough. In this way, if air or exhaust gas with a high proportion of air is recirculating, the idle cylinder group can quickly shift to normal operation, so that the responsiveness at the time of switching to all-cylinder operation is improved. There is also.

[0022]

Since the present invention is configured and operates as described above, since intake air is shut off by the intake control valve, partial cylinder operation can be performed without using the intake air shutoff valve, and conversely by the intake control valve. By performing partial cylinder operation, it is possible not only to reduce pumping loss of idle cylinders during partial cylinder operation, but also to reduce pumping loss of operating cylinders, and also to reduce pumping loss during all cylinder operation. It is possible. Further, when switching between full-cylinder operation and partial-cylinder operation, the intake control valve opening time in the case of full-cylinder operation is made shorter than that in the partial-cylinder operation, so that before and after switching between full-cylinder operation and partial-cylinder operation. The torque step is reduced. Furthermore, for a certain period of time immediately after switching between partial cylinder operation and all cylinder operation, the valve opening time of the intake control valve of the cylinder group that always operates is shortened stepwise from the valve opening time during partial cylinder operation, and By setting the valve opening time, the switching between the full cylinder operation and the partial cylinder operation is smoothly performed.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between an opening degree of an accelerator pedal and an opening degree of a throttle valve of the first embodiment.

FIG. 3 is a diagram showing an all-cylinder operating region and a partial-cylinder operating region of the first embodiment.

FIG. 4 is a diagram for explaining the operation of the intake control valve of the first embodiment.

FIG. 5 is a diagram showing a valve opening time of an intake control valve and a fuel injection time of a fuel injection valve before and after switching from a partial cylinder operation to an all cylinder operation in the first embodiment.

FIG. 6 is a diagram showing a valve opening time of an intake control valve and a fuel injection time of a fuel injection valve before and after switching from full cylinder operation to partial cylinder operation in the first embodiment.

FIG. 7 is a diagram showing output characteristics of a partial cylinder operation and an all cylinder operation of the first embodiment.

FIG. 8 is a diagram schematically showing a configuration of a second exemplary embodiment of the present invention.

[Explanation of symbols]

 1 ... Throttle valve 2 ... Surge tank 3a, 3b, 3c, 3d ... Combustion chamber 4a, 4b, 4c, 4d ... Intake passage 5a, 5b, 5c, 5d ... Intake control valve 6a, 6b, 6c, 6d ... Air bypass passage 6v ... Air bypass amount control valve 7a, 7b, 7c, 7d ... Fuel injection valve 8a, 8b, 8c, 8d ... Exhaust passage 9 ... Exhaust gas recirculation valve 10 ... Exhaust gas recirculation passage 11a ... Exhaust gas recirculation passage 12d ... Exhaust gas recirculation passage 12 ... Cooler 13 ... Negative pressure passage 14 ... Negative pressure reserve tank 15 ... Negative pressure passage 16 ... Negative pressure atmospheric pressure passage switching valve 17 ... ECU 18, 19, 20 ... Catalytic converter

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area F02D 21/08 311 A F02M 25/07 550 R 570 N

Claims (3)

[Claims] 1. An internal combustion engine comprising an intake time control means for arranging an intake control valve in the intake passage of each cylinder and controlling the opening time of the intake control valve, wherein the cylinder is deactivated during partial cylinder operation. The first cylinder group and the second cylinder group that operates even during partial cylinder operation are divided into the first cylinder group and the first cylinder group.
An exhaust gas recirculation valve is provided in an exhaust gas recirculation passage connecting a downstream side of the intake air control valve of the cylinder group and an exhaust gas passage, and when the load is low, the intake control valve of the first cylinder group is controlled to have a valve opening time of zero. The exhaust gas recirculation valve is opened, fuel injection is stopped and operation is stopped, only the second cylinder group is operated to perform partial cylinder operation, and when the load is high, the first cylinder group and the second cylinder group An internal combustion engine in which all the cylinders are operated by controlling the intake control valve with an equal opening time and closing the exhaust gas recirculation valve. 2. In switching between the full cylinder operation and the partial cylinder operation, the opening time of the intake control valve of the second cylinder group in the full cylinder operation is set shorter than that in the partial cylinder operation. The internal combustion engine according to claim 1, wherein: 3. Immediately after switching from the partial cylinder operation to the all cylinder operation, the intake control valve of the first cylinder group is set to a predetermined valve opening time during the all cylinder operation, and the intake control valve of the second cylinder group is opened in the previous period. The time is gradually shortened until the predetermined valve opening time is reached, and the fuel injection amount of the first cylinder group is gradually increased to a predetermined value during all-cylinder operation, so that the fuel injection amount of the second cylinder group is completely reduced. The internal combustion engine according to claim 2, wherein the internal combustion engine is gradually reduced to a predetermined value during cylinder operation.