JPH022904Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a multi-cylinder internal combustion engine in which one of three cylinders is configured as a supercharging cylinder for the remaining two combustion cylinders. It is.

[Conventional technology]

A multi-cylinder internal combustion engine in which one of the three cylinders is configured as a supercharging cylinder for the remaining two combustion cylinders is disclosed in Japanese Patent Application Laid-Open No. 1983-1999 as a prior art.
This is proposed by Publication No. 76517.

In other words, in this prior art multi-cylinder internal combustion engine, two of the three cylinders are used as four-stroke combustion cylinders with a phase shift of 360 degrees, and the remaining cylinder is used as a two-stroke supercharging cylinder. , the phase of the supercharging cylinder with respect to both the combustion cylinders.
180 degrees, and by matching the phase of the bottom dead center of the supercharging cylinder with the bottom dead center of the combustion cylinder, the entire amount of intake air for each of the two combustion cylinders is compressed in the supercharging cylinder. Air is alternately supplied to both combustion cylinders.

[The problem that the idea attempts to solve]

However, in a four-cycle combustion cylinder, in order to ensure the efficiency of filling intake air into the combustion cylinder,
The timing at which the intake valve starts to open is determined by adjusting the crank angle θ1 (θ1=10~
Since it is customary to set the phase of the supercharging cylinder to the front of both combustion cylinders by 20°,
When set to 180 degrees as in the prior art, the upward movement of the piston in the supercharging cylinder completely matches the downward movement of the piston in one of the two combustion cylinders, and The intake valve in the combustion cylinder opens when the supercharging cylinder is in the intake stroke before the compression stroke,
In other words, by opening the intake valve in the combustion cylinder when the supercharging cylinder is still in the intake stroke, the open section of the intake valve in the combustion cylinder and the intake stroke in the supercharging cylinder are separated. Because there is some overlap, the exhaust gas in the combustion cylinder during the exhaust stroke is stored in the supercharging cylinder from the time the intake valve in the combustion cylinder opens until the intake stroke of the supercharging cylinder ends. In this section, the air will flow backwards through the intake valve.

Therefore, during the intake stroke in the supercharging cylinder, the amount of intake air newly drawn into the supercharging cylinder is reduced by the amount of exhaust gas that has flowed back into the supercharging cylinder as described above.

In other words, the backflow of exhaust gas into the supercharging cylinder at the beginning of the opening of the intake valve in the combustion cylinder is due to the volumetric efficiency (ratio of the intake amount of atmospheric air to the stroke volume) in the supercharging cylinder, which in turn affects the supercharging cylinder. While reducing efficiency, the exhaust gas that flows back into the supercharging cylinder enters the combustion cylinder together with the compressed air again and inhibits combustion of the air-fuel mixture, so the increase in output due to supercharging is insufficient.

The present invention aims to solve the problems of this prior art.

[Means to solve the problem]

To achieve this objective, the present invention transforms two of the three cylinders that share a common crankshaft into four-cycle combustion cylinders with a phase shift of 360 degrees.
One cylinder is configured as a two-cycle supercharging cylinder, and the entire amount of intake air for each of the two combustion cylinders is compressed in the supercharging cylinder, and then the air is alternately supplied to the two combustion cylinders. In a multi-cylinder internal combustion engine, the phase of the bottom dead center of the supercharging cylinder with respect to both the combustion cylinders is set such that the phase of the bottom dead center of the supercharging cylinder is set so that the intake valve in the combustion cylinder starts to open, relative to the bottom dead center of the two combustion cylinders. It is configured so that it is shifted toward the front side in the rotational direction by a crank angle that is the same as or slightly larger than the crank angle from the position to the top dead center of the combustion cylinder.

[Functions and effects of the idea]

In this way, the phase of the bottom dead center of the supercharging cylinder with respect to both combustion cylinders can be adjusted from the position where the intake valve in the combustion cylinder starts to open, rather than the bottom dead center of the two combustion cylinders. If the crank angle is the same as or slightly larger than the crank angle up to top dead center, the compression stroke will be caused by the upward movement of the piston from bottom dead center in the supercharging cylinder. The timing at which the transition occurs coincides with the opening of the intake valve in one of the two combustion cylinders, or the piston in the supercharging cylinder moves upward from the bottom dead center. The timing of transition to the compression stroke is located closer to the rotational direction than the timing of the opening of the intake valve in one of the two combustion cylinders. The timing at which the intake stroke of the supply cylinder ends is made to coincide with the timing at which the intake valve in the combustion cylinder begins to open at the end of the exhaust stroke of the combustion cylinder, or the timing at which the intake valve begins to open is made to be earlier than the timing at which the intake valve begins to open. It can be placed on the side.

That is, it is possible to prevent the section in which the intake valve in the combustion cylinder is open from partially overlapping with the intake stroke in the supercharging cylinder, so that the intake valve in the combustion cylinder is opened during the intake stroke as in the prior art. By starting to open forward, it is possible to reliably prevent or reduce the exhaust gas in the combustion cylinder from flowing back into the supercharging cylinder.

Therefore, according to the present invention, the amount of new air that can be taken into the supercharging cylinder can be increased by the amount that can prevent or reduce the backflow of exhaust gas into the supercharging cylinder, so the volume in the supercharging cylinder can be increased. This has the effect of increasing engine output because efficiency, and ultimately supercharging efficiency, can be improved, and combustion inhibition due to backflow exhaust gas can be reduced.

〔Example〕

Hereinafter, an embodiment of the present invention will be explained with reference to the drawings. In the drawings, reference numeral 1 indicates that the first cylinder 2 and the third cylinder 4 are four-cycle combustion cylinders, and the second cylinder 3 is a four-cycle combustion cylinder.
shows an in-line three-cylinder internal combustion engine with two-cycle supercharging cylinders, each cylinder in the internal combustion engine 1 is composed of one crankshaft 1a, and the internal combustion engine 1 has the first cylinder Intake ports 5, 6 with intake valves 7, 8 and exhaust ports 9, 10 with exhaust valves 11, 12 are formed in the second and third cylinders 4, respectively, and one in the second cylinder 3. A suction port 13 is formed.

The pistons (not shown) of the first cylinder 2 and the third cylinder 4 move up and down in the same phase.
and the third cylinder 4, the ignition order is shifted by 360 degrees in crank angle so that when the first cylinder 2 is in the explosion stroke, the third cylinder 4 is in the intake stroke, and the intake valves 7 and 8 are As is conventionally known, from position A on the near side in the rotational direction by an appropriate crank angle θ1 (θ1 = 10 to 20 degrees) from the top dead center (TDC1) of the first cylinder 2 and the third cylinder 4, 1 cylinder 2 and 3rd cylinder 4
The intake port 5 is configured to open in the section of the crank angle θin from the bottom dead center (BDC1) to a position B on the rear side in the rotational direction by an appropriate crank angle θ2, and is opened and closed by the intake valves 7 and 8. ,6 is
It communicates with the inside of the second cylinder 3 via intake passages 14 and 15.

Further, the stroke volume of the second cylinder 3 is configured to be larger than the stroke volume of the first cylinder 2 or the third cylinder 4 in order to supercharge both the first cylinder 2 and the third cylinder 4. has been done.

On the other hand, a carburetor 19 with a throttle valve 18 is provided in the suction passage 17 from the air cleaner 16.
This suction passage 17 is connected to the suction port 13 in the second cylinder 3, and a check valve type suction valve 20 that opens only in the direction toward the second cylinder 3 is provided in the suction port 13. , the first cylinder 2
An exhaust manifold 21 is connected to exhaust ports 9 and 10 in the third cylinder 4.

The phase of the second cylinder 3 with respect to the first cylinder 2 and the third cylinder 4 is changed to the third cylinder 4 during the first compression stroke due to the upward movement of the piston in the second cylinder.
is the intake stroke, and the first cylinder 2 is set to be in the intake stroke when the second cylinder 2 is in the next compression stroke, so that the total amount of intake air for each of the first cylinder 2 and the third cylinder 4 is After the air is compressed in the second cylinder 3, it is configured to alternately supply air to the first cylinder 2 and third cylinder 4.

When the internal combustion engine 1 is viewed in the direction of the crankshaft 1a, the axis 23 of the cylinder bore in the second cylinder 3 is relative to the axis 22 of the cylinder bore in the first and third cylinders 4 of the crankshaft 1a.
By appropriately tilting the front side by an angle θ3 with respect to the rotation direction of It is set at a position shifted from the bottom dead center (BDC1) of the three cylinders 4 by an appropriate crank angle θ3 in the direction of rotation, and the crank angle θ3 in this case is The crank angle θ1 for the valves 7 and 8 is set equal to or slightly larger than the crank angle θ1.

Further, in another embodiment, by setting the crank pin of the second cylinder 2 at a phase of 180 degrees - θ3 in the rotational direction with respect to the crank pins of the first cylinder 2 and the third cylinder 4, the second cylinder The phase of the bottom dead center for the first cylinder and the third cylinder may be located on the near side in the rotational direction by the crank angle θ3 with respect to the bottom dead center of the first cylinder and the third cylinder.

Note that when using a fuel injection system instead of the fuel supply by the carburetor 19, an air flow meter is provided downstream of the air cleaner 16, and an amount of fuel corresponding to the amount of air measured by the air flow meter is supplied.
The fuel may be injected and supplied to the suction passage 17, the suction port 13, the second cylinder 3, or the first cylinder 2 and the third cylinder.

In this configuration, when the piston of the second cylinder 3 is in the suction stroke in which it descends, the first cylinder 2 is in the compression stroke,
The third cylinder 4 is on the exhaust stroke, and the intake valves 7 and 8 in both cylinders 2 and 4 are both closed, so the intake air from the air cleaner 16 is supplied with fuel into the second cylinder 3. It is later inhaled. Next, when the second cylinder 3 enters the compression stroke due to the upward movement of the piston, the third cylinder 4 shifts from the exhaust stroke to the intake stroke, and during this transition, its intake valve 8 opens, so that the second cylinder 3 The compressed air-fuel mixture is supplied to the third cylinder 4 via the intake passage 15, supercharging the third cylinder 4, and
When the cylinder 3 enters the next compression stroke, the first cylinder 2 shifts from the exhaust stroke to the intake stroke, and during this transition, the intake valve 7 opens, so that the air-fuel mixture compressed in the second cylinder 3 is released. Intake passage 1 in first cylinder 2
Air is supplied through the cylinder 4, and the first cylinder 2 is supercharged.

In this case, the phase of the bottom dead center (BDC2) of the second cylinder 3 with respect to the first cylinder 2 and the third cylinder 4 is set to be lower than the bottom dead center (BDC1) of the first cylinder 2 and the third cylinder 4. The crank angle θ3 is the same as or slightly larger than the crank angle θ1 from the position A where the intake valves 7 and 8 in the first cylinder 2 and the third cylinder 4 begin to open to the top dead center (TDC1) of the first cylinder 2 and the third cylinder. By shifting the position toward the front side with respect to the rotation direction, the first
The crank angle between the position A where the intake valves 7 and 8 in the second and third cylinders 4 begin to open and the bottom dead center (BDD2) in the second cylinder 3 is 180 degrees or less than 180 degrees. , the timing when the second cylinder 3 shifts to the compression stroke due to the upward movement from the bottom dead center (BDC2) of the piston in the second cylinder 3 is the intake valve 7 in the first cylinder 2 and the third cylinder 4, 8 starts to open, or it is before the timing when the intake valves 7 and 8 start to open, so when the intake valves 7 and 8 in the first cylinder 2 and the third cylinder 4 start to open. In this way, it is possible to prevent or reduce the exhaust gas in these cylinders from flowing back into the second cylinder 3.

In the above embodiment, the central second cylinder in a three-cylinder internal combustion engine is used as a supercharging cylinder, but the first cylinder 2 or the third cylinder 4 is used as a supercharging cylinder, and the other cylinders are used as supercharging cylinders. It goes without saying that it may also be used as a combustion cylinder.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a plan view of an internal combustion engine, and FIG. 2 is a diagram showing the phase relationship when the engine is viewed in the direction of the crankshaft. 1... Internal combustion engine, 2... First cylinder (combustion cylinder), 3... Second cylinder (supercharging cylinder), 4... Third cylinder
Cylinder (combustion cylinder), 5, 6...Intake port, 7,
8... Intake valve, 13... Intake port, 14, 15
...Intake passage, 16...Air cleaner, 17...
Suction passage, 18...throttle valve, 19...carburizer, 20...suction valve.

Claims (1)

[Scope of utility model registration request] Of the three cylinders that share a common crankshaft, two cylinders are configured as four-cycle combustion cylinders whose phases are shifted by 360 degrees from each other, and one cylinder is configured as a two-cycle supercharging cylinder, and In a multi-cylinder internal combustion engine in which the entire amount of intake air for each cylinder is compressed in the supercharging cylinder and then alternately supplied to both the combustion cylinders, the bottom dead center of the supercharging cylinder is The phase for both combustion cylinders is set below the bottom dead center of both combustion cylinders.
The intake valve in the combustion cylinder is shifted from the opening position to the top dead center of the combustion cylinder by a crank angle that is the same as or slightly larger than the crank angle in the rotation direction. Features a supercharged multi-cylinder internal combustion engine.