JPH03264768A - Intake device of multivalve engine - Google Patents

Abstract

PURPOSE:To improve combustibility by delaying fuel supply timing around a spark plug by a central intake port out of a plurality of the intake ports, provided in a single cylinder, from intake air supply timing to a combustion chamber by the intake ports on both sides. CONSTITUTION:In a three-intake valve fuel injection engine, three independent intake ports 11 to 13, branched from a single intake port, are formed in a cylinder bore left side part of a cylinder head 2. Here, combustion chamber side openings of the intake ports 11, 13 on both sides are parallelly provided in a longitudinal direction of the engine, and on the other hand formed in a position apart from the center of a cylinder bore farther than the central intake port 12. Fuel supply timing around a spark plug 102 by the central intake port 12 is set to be delayed from intake air supply timing to a comustion chamber 7 by the intake ports 11, 13 on both sides, by providing the spark plug 102 on a line of connecting the center of the central intake port 12 to the center of the cylinder bore.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an intake system for a multi-valve engine having three intake valves, and more particularly to one that injects and supplies fuel from an intake port via a central intake valve. .

(Prior Art) Conventionally, as an intake system for this type of multi-valve engine, as disclosed in, for example, Japanese Utility Model Application No. 61-204922, each cylinder has an intake valve driven by a camshaft and an intake passage. Three intake ports are branched and open on one side of the combustion chamber through the intake valves to achieve high intake and exhaust efficiency, and a fuel injection valve is used to connect the central intake port of the three intake ports to one side of the combustion chamber. Types that inject fuel are known. And in this case,
A spark plug is provided near the center of the cylinder bore on a line connecting the center of the opening of the central intake port and the center of the cylinder bore, and located on the other side of the combustion chamber from the opening of the intake port. Lean combustion is achieved by supplying a rich air-fuel mixture to the spark plug located near the central intake port at a fuel supply timing that is synchronized with the intake port.

(Problem to be Solved by the Invention 8) By the way, in general, in order to improve the efficiency of intake air (fuel) into the combustion chamber and the efficiency of exhaust gas from the combustion chamber, the intake stroke starts when the intake port begins to be opened by the intake valve. The opening and closing timings of the intake and exhaust valves are set so that the initial stage and the final stage of the exhaust stroke, when the exhaust valve finishes closing the exhaust port, overlap. In this way, when the intake/exhaust overlap period is provided, intake air and fuel (mixture) are supplied into the combustion chamber with some exhaust gas still remaining in the combustion chamber, so the central intake port is Even though the 1#i mixture from mixture) cannot be collected. For this reason, combustion stability deteriorates at times of low load such as when idling, and the operating limit performance cannot be improved when performing lean combustion, and knocking is more likely to occur.

The present invention has been made in view of this point, and its purpose is to move the exhaust gas toward the outer circumferential side from the center of the cylinder bore by using the intake air supplied from the intake ports on both sides.
In this state, the air-fuel mixture from the central intake port is collected around the spark plug, improving combustion stability at low loads such as idling and improving operating limit performance through lean combustion, as well as suppressing knocking. It is something that we try to do.

(Means for solving the problem) In order to achieve the above object, the solution taken by the present invention is as follows:
Each cylinder has an intake valve driven by a camshaft, three intake ports that branch from the intake passage and open on one side of the combustion chamber through the intake valves, and a central intake port of the three intake ports. The present invention is based on an intake system for a multi-valve engine that includes a fuel injection valve that injects fuel into an intake port. A spark plug is provided near the center of the cylinder bore on a line connecting the center of the opening of the center intake port and the center of the cylinder bore and located on the other side of the combustion chamber than the intake port opening, and The timing of supplying fuel to the vicinity of the spark plug is set later than the timing of supplying intake air to the combustion chamber through the intake ports on both sides.

(Function) With the above configuration, in the present invention, during the intake/exhaust overlap period, exhaust gas is mixed in the intake air by the swirl generated along the outer circumference of the cylinder bore by the intake air from the intake ports on both sides. The air-fuel mixture is pushed toward the outer circumference of the cylinder bore, and then the air-fuel mixture is supplied around the spark plug from the central intake port. In that case, the air-fuel mixture supplied around the spark plug is
The swirl generated along the outer periphery of the cylinder bore induces swirl around the spark plug, resulting in good mixing, and the mixture is collected around the spark plug as a pure air-fuel mixture with no exhaust gas mixed in. This improves combustion stability at low loads such as idling, improves operating limit performance when performing lean combustion, and suppresses knocking under any load conditions. become.

(Example) Embodiments of the present invention will be described below based on the drawings.

3 to 5 show a V-type six-cylinder fuel injection engine equipped with an intake system having three intake valves according to an embodiment of the present invention. Although these figures show only one cylinder as a representative, the other cylinders also have the same configuration. In these figures, 1 is the cylinder block, 2 is the cylinder block 1
The cylinder head 3 disposed above is a cam housing disposed above the cylinder head 2.

A cylinder 5 is formed in the cylinder block 1, and a piston 6 is slidably fitted into the cylinder 5. The cylinder head 2 also has two inclined walls 7a, 7.
A pent-roof-shaped combustion chamber 7 is formed.

On the left side of the cylinder bore of the cylinder head 2, there are three first to third ports that branch from one intake port 10 on the left side wall of the cylinder head and lead fresh air (intake) to the cylinder 5.
Independent intake port 11. 12° and 13° are provided.

One end of each of the first to third independent intake ports 11 to 13 opens to the inclined wall 7a on the left side of the combustion chamber 7 (one side of the combustion chamber) through the valve seat 14 on the intake side, and the other end opens to the cylinder. It is provided so as to open on the left side wall of the head (intake port 10). 1st on both sides. Third independent intake port 11
．． The combustion chamber side openings 13 are lined up in the engine longitudinal direction (vertical direction in FIG. 1, which will be described later), and are provided at a position farther from the cylinder bore center than the central second independent intake port 12. These three first to third independent intake ports 1
1 to 13 are gathered in the single intake port 10.

Furthermore, on the right side of the cylinder bore of the cylinder head 2, there are two independent exhaust ports 21.
22 are provided. This independent exhaust bow) 21.22
are provided so that one end opens on the inclined wall 7b on the right side of the combustion chamber 7 (the other side of the combustion chamber) through the valve seat 23 on the exhaust side, and the other end opens on the right side wall of the cylinder head. . The combustion chamber side openings of these two independent exhaust ports (21, 22) are lined up in the front and back direction of the engine. Further, the two exhaust ports 21 and 22 are combined into one exhaust port 20 on the right wall side of the throat toward the cylinder.

The cylinder head 2 has a first to third independent intake port 11 which corresponds to the first to third independent intake ports 11 to 13, and which corresponds to the first to third independent intake ports 11 to 13.
Three first to third intake valves 31, 32, and 33 are provided to open and close combustion chamber side openings (valve seats) 14). Each of the first to third intake valves 31 to 33 includes an umbrella-shaped valve head portion 31a to 33a arranged in the opening, and a valve shaft 31b extending upward from the valve head portion 31a to 33a.
-33b, respectively, and the valve shafts 31b-33
b is slidably fitted into the cylinder head 2 and is movable up and down. These intake valves 31 to 33
Disc-shaped spring seats 51, 52 . are provided at the end of the valve shaft.
53 are attached respectively, and this spring seat 51
Valve spring 6 between ~53 and cylinder head 2
1,62° 63 are compressed, and their spring force urges each intake valve 31 to 33 upward, that is, in the valve closing direction.

These three first to third intake valves 31 to 33 are inclined to the left side of the cylinder bore toward the end of the valve shaft, and the valve shafts 31b to 33 are inclined toward the left side of the cylinder bore toward the end of the valve shaft.
33b are provided parallel to each other.

The cylinder head 2 also has an independent exhaust port 21.2.
Two exhaust valves 41 and 42 are provided to open and close two combustion chamber side openings (valve seats 23), respectively. These exhaust valves 41, 42 have the same structure as the above-mentioned intake valves 31 to 33, and are provided so as to be movable up and down.
Valve springs 64 and 65 are provided to bias the valve in the valve closing direction.

These two exhaust valves 41 and 42 are provided so that they are inclined to the right side of the cylinder bore toward the end of the valve shaft, and the valve shafts 41b and 42b are parallel to each other.

Next, the drive mechanism of the intake/exhaust valves 31 to 33, 41, and 42 will be explained. On the left and right sides of the cam housing 3, there are camshafts 91 exclusively for intake and exclusively for exhaust, which extend in the longitudinal direction of the engine. 92 are arranged respectively. These two camshafts 91 and 92 are driven by an engine output shaft (not shown), and the intake camshaft 9] is driven clockwise in FIG.
2 rotates counterclockwise in the same figure. Further, the intake camshaft 91 is integrally formed with three intake cams 93 corresponding to each of the intake valves 31 to 33, and the exhaust camshaft 92 is integrally formed with two exhaust cams corresponding to each of the exhaust valves 41 and 42. 94 are integrally formed.

The first to third intake valves 31 to 33 are driven by an intake camshaft 91 via swing arms 81, 82, and 83. That is, the cylinder head 2 is provided with known hydraulic lash adjusters 71, 72, and 73. The hydraulic lash adjusters 71 to 73 are provided with support portions. The swing arms 81 to 83 have one end resting on the support portion of the hydraulic lash adjuster 71 to 73, and the other end resting on the first to third intake valves 3.
They are provided so as to ride on the end portions of the valve shafts Nos. 1 to 33, respectively. Furthermore, rollers having rotating shafts extending in the longitudinal direction of the engine are provided at midpoints of the swing arms 81 to 83, and these rollers are in contact with the intake cams 93, respectively. Therefore, when the intake camshaft 91 rotates, the rollers move up and down in accordance with the lift amount of the intake cam 93, which causes the swing arms 81 to 83 to swing up and down around the end on the hydraulic lash adjuster side. move. For this purpose, the ends of the swing arms 81 to 83 on the valve shaft end side swing up and down according to the arm ratio, and the first to third intake valves 31 to 33 open and close in accordance with the reciprocating movement of these ends. It looks like this.

In addition, the exhaust valves 41 and 42 are also connected to the exhaust dedicated camshaft 92.
is driven via swing arms 84 and 85.

This drive mechanism is configured to include hydraulic lash adjusters 74 and 75 that support swing arms 84 and 85 as in the case of the intake valves 31 to 33, and when the exhaust camshaft 92 rotates, the exhaust cam The rollers of the swing arms 84, 85 move up and down according to the lift amount of the swing arms 84, 85, and the swing arms 84, 85 swing up and down centering on the end on the hydraulic lash adjuster side. The end on the valve shaft end side swings up and down in accordance with the arm ratio, and the exhaust valves 41 and 42 open and close in accordance with the up and down movement (reciprocation) of this end.

Furthermore, a plug hole 101 is provided to penetrate through the cylinder head 2 and cam housing 3 above the combustion chamber 7, and a spark plug 102 is inserted into the plug hole 101.
It is installed so that the ignition point 102a is located in the combustion chamber 7. The plug hole 101 and the spark plug 102 are provided parallel to the valve shafts 41b, 42b of the exhaust valves 41, 42 so that the ignition point 102a is located at the center of the bore of the combustion chamber 7, and the flame from the ignition point 102a is The propagation causes combustion of the fuel within the combustion chamber 7.

Then, as shown in Fig. 1, the three
In the cylinder head 2 above the independent intake ports 11 to 13, fuel is injected only to the intake air distributed to the second independent intake port 12 among the intake air distributed to the first to third independent intake ports 11 to 13, respectively. Injector 1 for supplying
03 (fuel injection valve) is provided. The injector 103 has a nozzle hole 103a that injects fuel from above the second independent intake port 12 toward a portion of the valve head portion 32a of the second intake valve 32 located closer to the spark plug 102. .

Next, the three first to third independent intake ports 11 to 13 are opened by reciprocating (lifting) the first to third intake valves 31 to 33.
The opening/closing timing will be explained based on the characteristic diagram shown in FIG. In this characteristic diagram, the first and third intake valves 31.
33 reciprocating first and third independent intake ports 11
．． The opening and closing timings of the first and third independent intake ports 11 and 13 are the same, and the opening and closing timings of the first and third independent intake ports 11.
The opening/closing timing of the second independent intake port 12 due to the reciprocating movement of the intake valve 32 is made different.

The characteristic diagram will be explained based on the above-mentioned premise.

In FIG. 2, the second intake valve 32 opens later than the first and third intake valves 31 and 33, and the opening/closing timing of the second independent intake port 12 by the second intake valve 32 is set to The opening/closing timing of the first and third independent intake ports (11.13) by valves 31.33 is delayed. In this case, at the end of the exhaust stroke when the two exhaust valves 41.42 are about to close the independent exhaust ports 21 and 22, and when the first and second intake valves 31.33 close the first and third independent intake ports 11.13. There is a valve overlap period in which the valve overlaps with the beginning of the intake stroke when the valve begins to open, and during this valve overlap period, the exhaust gas still left in the combustion chamber 7 is shown by the diagonal arrow in FIG. As shown in FIG. This causes it to be pushed toward the outer periphery of the cylinder bore. Then, the air-fuel mixture from the central intake port 12 is transferred to the second intake valve 32 during a period other than the intake stroke, that is, during the exhaust stroke or the fat expansion stroke.
When the temperature of the valve head part 32a reaches the highest temperature, the mixture is blown from the nozzle hole of the fuel injection valve 103 and burns as a mixture in which the temperature of the valve head part 32a is taken away and atomization is promoted by the heat. Spark plug 102 in chamber 7 (spark plug 102a
) (inner circumferential side of the cylinder bore).

Therefore, in the embodiment described above, the air-fuel mixture supplied around the spark plug 102 pushes toward the outer circumferential side of the cylinder bore while mixing the exhaust gas with the intake air, as shown by the white arrow in FIG. Swirl generated along the outer circumferential side of the cylinder bore induces swirl around the spark plug 102 for good mixing, and the mixture is effectively collected around the spark plug 102 as a pure air-fuel mixture without any exhaust gas mixed therein. become.

For this reason, it is possible to improve combustion stability at low loads such as when idling, and to improve the operating limit performance when executing lean combustion. Knocking can be suppressed.

It should be noted that the present invention is not limited to the above embodiments, but includes various other modifications.

For example, in the above embodiment, the first. 3rd intake valve 31°33
The opening and closing timings of the first and third independent intake ports 11 and 13 were made the same, but as shown in FIG.
The opening/closing timing of the first independent intake port 11 by the intake valve 31 is determined by the opening/closing timing of the first independent intake port 11 by the third intake valve 33.
to open even earlier than the opening/closing timing of
As shown in FIG. 7, the lift speed when the first independent intake port 11 is opened by the first intake valve 31 is faster than the lift speed when the third independent intake port 13 is opened by the third intake valve 33. In these cases, the directionality of the swirl generated along the outer circumferential side of the cylinder bore within the combustion chamber 7 becomes more pronounced.

Further, in the above embodiment, the first. Third independent intake port 11
．． The combustion chamber side opening of No. 13 is provided at a position farther from the cylinder bore center than the second independent intake port 12, and the second intake valve 32 of the second independent intake port 12 is provided at a position farther from the cylinder bore center than the second independent intake port 12. The first two on both sides may have opened late. Third
The combustion chamber side openings of independent intake ports 11 and 13 are connected to the second
The independent intake port 12 is provided at a position closer to the center of the cylinder bore, and the spark plug 102 is provided near the center of the cylinder bore, and the opening/closing timing of the first to third independent intake boats 11 to 13 by the first to third intake valves 31 to 33 is adjusted. are made the same, so that the timing at which fuel is supplied around the spark plug 102 by the second independent intake port 12 is delayed from the timing at which intake air is supplied to the combustion chamber 7 by the first and third independent intake ports 11.13. In this case, the third independent intake ports 11-1
Even though the opening and closing timings of the first and third independent intake ports are the same, before the air-fuel mixture supplied from the second independent intake port 12 reaches the spark plug 102 located near the center of the cylinder bore, the first open and close timing near the center of the cylinder bore changes. Third independent intake port 11.13
The exhaust gas remaining in the combustion chamber 7 is pushed toward the outer circumferential side of the cylinder bore together with the intake air.

Furthermore, in the above embodiment, a swirl is generated by the intake air supplied into the combustion chamber 7 along the outer circumferential side of the cylinder bore from the first and third independent intake bows 11. A mask may be provided on the peripheral wall (cylinder head side) of each valve in the combustion chamber of the third intake valve or the first and third intake valves. A mask may be provided in the three independent intake ports 11.13, or each boat of the first or third independent intake ports 11.13 or the first and third independent intake ports 11.13 may be formed in a helical shape. Of course, the generation of swirl by the intake air from each boat may be further promoted.

(Effects of the Invention) As described above, according to the multi-engine intake system of the present invention, the timing of fuel supply around the spark plug by the central intake boat is changed from the timing of supplying fuel to the combustion chamber by the intake ports on both sides. During the intake/exhaust overlap period, the exhaust gas still remaining in the combustion chamber is mixed with the intake air from the intake ports on both sides, and the central intake air is pushed toward the outer circumference of the cylinder bore by the swirl. Combined with the swirl induction effect, only the pure air-fuel mixture from the port is mixed well and effectively collected around the spark plug.
Combustion stability at low loads such as idling and operating limit performance due to lean combustion can both be improved, and knocking can be suppressed at full loads.

[Brief explanation of drawings]

1 to 5 show embodiments of the present invention, FIG. 1 is a plan perspective view of the combustion chamber, FIG. 2 is a characteristic diagram showing the opening timing characteristics of each independent intake boat by the intake valve, and FIG. The figure is a sectional view taken along the ■-■ line in Figure 1, and Figure 4 is the T in Figure 1.
5 is a sectional view taken along line V-TV in FIG. 1. FIG. Further, FIGS. 6 and 7 are views corresponding to FIG. 2 showing each modification example. 5... Cylinder 7... Combustion chamber 10... Intake port (intake passage) 11.12.13... Independent intake port (intake port) 31.32.33... Intake valve 91... Intake-only camshaft (camshaft)] 02...Spark plug 10B...Injector (fuel injection valve) 5...Cylinder 7...Combustion chamber 10...Intake port (intake passage) 11.12. 13...Independent intake port (intake port) 31, 32.33...Intake valve 91...Intake-only camshaft (camshaft) 102...Spark plug 103...Injector (fuel injection valve)■ No. Figure 1 (Le 478-

Claims (1)

[Claims] (1) For each cylinder, an intake valve driven by a camshaft, three intake ports that branch from the intake passage and open on one side of the combustion chamber through the intake valves, and
In an intake system for a multi-valve engine equipped with a fuel injection valve that injects fuel into a central intake port among two intake ports, the air intake system is located near the center of the cylinder bore on a line connecting the center of the opening of the center intake port and the center of the cylinder bore; A spark plug is provided in a portion located on the other side of the combustion chamber from the intake port opening, and the timing of supplying fuel to the vicinity of the spark plug through the central intake port is determined by the timing at which fuel is supplied to the combustion chamber through the intake ports on both sides. An intake system for a multi-valve engine characterized by being set later than the supply timing.