JPH03164518A - Suction device of multivalve engine - Google Patents

Abstract

PURPOSE:To improve the combustibility in an engine having a center port and two side ports disposed on both sides thereof by communicating side ports adjacent to each other between the respective cylinders with each other, and positioning an ignition plug on the extension of the central axis of the center port. CONSTITUTION:In the case of executing the above suction system in a straight- type four-cylinder engine, the first intake valve 7 is disposed in the central portion in the cylinder array direction of a combustion chamber 5, the second and third intake valves 8, 9 are disposed on both sides of the above valve, and the first and second exhaust valves 10, 11 are disposed. There are provided the first to third intake passages 12-14 opened and closed by the respective intake valves 7-9. A fuel injection valve 21 is installed in the central first intake passage 12. In this case, the second and third intake passages 13-14 adjacent to each other between the respective cylinders are communicated with each other to form a common port portion 16, and an ignition plug 6 ds positioned on the extension of the central axis of the first intake passages 12. By this arrangement, supplied fuel is prevented from adhering to the wall surface of the cylinder so as to improve the exhaust emission performance.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake system for a multi-valve engine having a plurality of intake valves per cylinder.

(Prior Art) With the recent trend toward higher engine output, various types of multi-intake valve engines having a plurality of intake valves per cylinder have recently been developed. As one such multi-valve engine, the combustion chamber t? 7. There is a helical type intake boat that can generate a 7-hole, and the structure of the intake boat is arranged in several places as shown below. First of all, a helical intake boat, as its name suggests, has a spiral intake boat, and the spiral intake boat improves combustion performance by generating swirl within the engine combustion chamber. be.

However, in the case of an engine with a single intake boat, it has been recognized that during high-speed, high-load operation, the intake resistance increases due to the special boat shape, and the intake air filling efficiency tends to decrease. Therefore, in order to improve this, in addition to the above-mentioned helical type (first) intake boat and (first) intake valve, a second normal intake boat (straight boat) was added.
The second intake boat is further provided with an intake control valve (swirl control valve), and this intake control valve is closed during low-load operation to achieve the characteristics of the helical intake boat. In addition, during high rotation and high load operation, this intake control valve is opened to introduce air into the combustion chamber from both the intake boat of the helical cylinder 1 and the second intake boat. By doing so, intake resistance can be reduced and intake air filling efficiency can be increased.

By the way, in general, in order to improve combustibility and improve fuel efficiency in internal combustion engines, it is necessary to expand the maximum value of the combustible air-fuel ratio of the mixture, that is, the lean limit of combustion. It is known that it is good to make the fuel around the plug richer and thinner near the piston (hereinafter referred to as stratification of the air-fuel mixture).

Therefore, for example, the first intake boat which is always open and which generates a swirl in the intake air supplied into the engine combustion chamber;
It has an intake control valve that opens only in the high-load/high-speed operating range of the engine, and supplies intake air straight into the combustion chamber.''In addition to the second intake boat,
a straight small-diameter third intake boat with a fuel injection valve provided between the two intake boats, and a third intake valve;
These first, second and third intake boats are connected to the first, second and third intake boats.
and a combustion chamber through a third intake valve, and for example, when the load is low, the opening timing of the third intake valve is delayed by a predetermined crank angle than the opening timing of the first intake valve. It is conceivable that stratification of the air-fuel mixture can be achieved to achieve both the improvement in combustibility and the improvement in fuel efficiency due to lean combustion.

By the way, in a dual intake valve engine with such a configuration, fuel is supplied only from the third intake boat and the third intake valve, or the third intake valve generally has a small valve diameter. In addition, the third intake boat on which the third intake valve is provided has a small diameter and a small cross-sectional area as described above. Therefore, the injected fuel tends to adhere to the inner wall of the intake boat, so when a large amount of fuel is required, such as when the engine is in a high-load/high-speed range, the required amount of fuel cannot be drawn into the combustion chamber smoothly. There's a problem.

In addition, since the opening period of the third intake valve is normally from around the center of the intake stroke to around the bottom dead center of the intake stroke, there is also the problem that it is difficult to obtain a homogeneous air-fuel mixture during full load operation. be.

Therefore, we have solved this problem and reduced the engine load.
It achieves good stratification in the low engine speed range and expands the lean limit of combustion, while at the same time allows the engine to smoothly supply the required amount of homogeneous air-fuel mixture in the high load/high engine speed range. Conventionally, for example, in the 1980s, there were
There is an invention disclosed in Publication No. 3-14828.

That is, in order to solve the above-mentioned problems, the engine intake system of the invention includes a first intake boat that is always open to generate a swirl in the intake air supplied into the combustion chamber, and a high-load engine. - Equipped with a second intake boat that has an intake control valve that opens only in a high-speed operating range and supplies straight intake air into the combustion chamber, and a third intake boat that is provided with a fuel injection valve. 1/2nd
and a third intake boat are formed to be independent from each other, and the first, second and third intake boats are connected to the engine combustion chamber via the first, second and third intake valves, respectively. In a multi-intake valve engine, in which the opening timing of the third intake valve is delayed from the opening timing of the first intake valve, in addition to the third intake boat, the opening timing of the third intake valve is delayed from that of the first intake valve. Fuel injection valves are provided at three locations in the middle of the boat and on the downstream side of the intake control valve of the second intake boat. While the fuel is supplied only from the fuel injection valves provided in the first, second, and third intake boats, when the engine is in a high-load, high-speed range, fuel is supplied from all of the fuel injection valves provided in the first, second, and third intake boats. It is composed of

In other words, in the configuration of the invention, in the low-load, low-speed range of the engine, only the fuel injection valve in the third intake boat is actuated to supply fuel in the latter half of the intake stroke, thereby eliminating the need for the conventional double intake valve described above. Achieve stratification similarly to the engine. On the other hand, in the high load/high rotation range of the engine,
All of the fuel injection valves in the first, second, and third intake boats are operated to efficiently supply a large amount of fuel without causing wall adhesion, thereby achieving a homogenized required amount. This allows the air-fuel mixture to flow smoothly into the combustion chamber, improving driving performance and producing high output.

(Problem to be Solved by the Invention) However, according to the configuration of the prior art described above, as mentioned above, the first to third intake boats corresponding to the first to third three intake valves are 3, each of which is completely independent of each other.
It has a main intake passage (three intake branch pipes), which are arranged in parallel on the same horizontal plane in the cylinder arrangement direction, and face each other across the third intake boat, which is the center port. The intake air introduction directions of the first and second intake boats (side boats) are arranged to face (collide with) the direction of the inner peripheral surface of the cylinder bore. Therefore, for example, the fuel supplied from the first and second intake boats (side ports) adheres to the peripheral wall of the cylinder in the form of droplets, and the droplet fuel is attached to the tonneau brand of the piston, which is the source of HC generation. This includes the problem that it is easy to get into the vicinity of the step between the first ring groove and the throat surface of the cylinder.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the above problems, and includes a center port provided at the center of each cylinder in the direction of the seven-ring arrangement, and a center port provided on both sides of the center port. In a multi-valve engine comprising two side ports provided on both sides in the cylinder arrangement direction and a fuel injection valve provided at the center port, the mutually adjacent side ports between the cylinders are communicated with each other. The present invention is characterized in that it is formed into a common boat and that the spark plug is located on the central axis extension line of the center port.

(Function) In the configuration of the intake device of the multi-valve engine of the above claimed invention,
A center port provided in the center of each cylinder in the cylinder arrangement direction, two side ports provided on both sides of the cylinder arrangement direction with the center port in between, and a fuel injection valve provided in the center port. In the multi-valve engine, four adjacent side ports between the cylinders are formed into a common boat that communicates with each other, and the spark plug is located on an extension of the center axis of the center port.

In this way, the center port and the two that sandwich the center port are
If you adopt a three-valve structure with three intake boats with two side ports, and three corresponding intake valves, it is natural that the opening area of the intake valves will increase and the intake resistance will decrease. By improving the shape of the combustion chamber, the compression ratio can be made sufficiently high, and by widening the opening area of the exhaust valve accordingly, the exhaust resistance is reduced, which improves both intake air filling efficiency and scavenging performance. It becomes possible to increase the rotation speed and also improve the output.

Furthermore, in engines equipped with three or more intake valves, various specifications such as the shape and location of the intake valves or intake ports, opening and closing timing, etc. can be set individually to a certain degree. Therefore, by devising the specifications of each intake valve or intake boat in this way, it is possible to further improve the engine output characteristics and fuel efficiency.

For example, as in the three-intake valve type engine disclosed in the above-mentioned Japanese Utility Model Publication No. 63-14828, one predetermined intake boat is closed in a predetermined low load/low rotation range,
Intake air flows into the engine combustion chamber from the helical-shaped intake boat of the pond to form a swirl in the engine combustion chamber, thereby improving combustibility in the low rotation range. In the high rotation range, it is relatively easy to unblock the one intake boat mentioned above and efficiently supply intake air from all three intake boats into the combustion chamber to improve engine output. I can do it.

Furthermore, in the case of the intake passage of the present invention, the two side ports between adjacent cylinders are made to communicate with each other to form a common boat, and the spark plug is positioned on the extension line of the central axis of the center port. Since the direction of incidence into the combustion chamber of the center port is set toward the spark plug at the center of the cylinder bore, the injected fuel supplied from the fuel injection valve is efficiently collected near the spark plug without adhering to the wall surface. You will be able to do it.

As a result, it is less likely that the injected fuel will adhere to the wall surface of the 7th ring in the form of droplets and enter the vicinity of the piston top land during compression, which is the case in the past, and the amount of HC generated will be reduced. At the same time, the common boat side port opens toward the center of the 7 cylinder bore, forming a vortex flow from around the cylinder bore toward the center, resulting in good mixing of fuel and air. The air-fuel mixture is efficiently stratified, and the combustibility and exhaust emission performance are improved.

Furthermore, since the adjacent side ports of each cylinder are made common, the installation space of the intake manifold in the horizontal plane direction is reduced, and the space factor of the intake system is greatly improved.

(Effects of the Invention) Therefore, according to the multi-valve engine intake system of the present invention, it is possible to prevent the supplied fuel from adhering to the cylinder wall surface at high speeds and high loads, thereby reducing the amount of HC generated. , can improve exhaust emission performance.

In addition, the vortex flow toward the center of the cylinder bore by the common boat improves the mixing performance of the air-fuel mixture during engine operation, and the supply of fuel from the center boat to the vicinity of the spark plugs makes it possible to stratify the air-fuel mixture. It is possible to improve combustion performance and fuel efficiency during low-load operation.

Moreover, as a result of the common intake boat between each cylinder,
Even though a large-diameter intake boat structure is adopted due to the multi-valve structure, the overall shape of the intake system can be made compact, which in turn can contribute to downsizing of the engine.

(Embodiment) FIGS. 1 and 2 show the intake air of a multi-valve engine according to a first embodiment of the present invention, which is provided with a plurality of cylinders and each cylinder of the plurality of cylinders is provided with m number of intake valves. The configuration of the device is shown.

First, the configuration will be explained with reference to FIGS. 1 and 2. Reference numeral 1 indicates an engine main body of an engine equipped with four cylinders, first to fourth arranged in series, and 2 indicates a cylinder block for each cylinder. , 3 is a piston that reciprocates within the cylinder block 2 of each cylinder, 4 is a cylinder head fixed on the 7-ring block 2 of each cylinder, and 5 is a piston 3 of each cylinder and a rod to the same cylinder. Reference numeral 4 indicates an engine combustion chamber formed between the engine combustion chamber 5 and the engine combustion chamber 5, and 6 indicates a spark plug of each cylinder, which is disposed approximately at the center of the top of the engine combustion chamber 5. Then, to the 7 rings of each cylinder, three intake valves consisting of a first intake valve 7, a second intake valve 8, and a third intake valve 9 are installed on the inner wall surface of the door 4, and a first exhaust valve. Two exhaust valves, each consisting of a valve 10 and a second exhaust valve 11, are arranged.

The first intake valve 7 and the second and third intake valves 8.9 are formed to have approximately the same valve diameter. The first intake valve 7 is disposed at the center of the engine combustion chamber 5 in the cylinder arrangement direction (vertical direction in FIG. 2), and
The spark plug 6 is located on the extension line of -7. Inside the shifter head 4 of each cylinder, there are three intake passages consisting of a first intake passage 12, a second intake passage 13, and a third intake passage 14, and the first and second exhaust valves 1.
Exhaust passages 15Δ and 15B connected to the engine combustion chamber 5 through 0°11 are formed, respectively.

The first intake passage 12, the second intake passage 13, and the third intake passage 14 are separated from each other in the intake boat section, as shown in the figure, and extend substantially parallel to each other within the printer head 4. and a first intake passage 12;
As will be described in detail later, the second intake passage 13 and the third intake passage 14 are such that the adjacent intake passages between each cylinder are shared in the middle, while the intake passages (not shown) On the upstream side, they are all connected to the same intake branch pipe so that all the passages merge with each other inside the same intake branch pipe. The third intake passage 14 is connected to the engine combustion chamber 5 via a third intake valve 9. Further, the second intake passage 13 is connected to the engine combustion chamber S via the second intake valve 8. Furthermore, the first
The intake passage 12 is connected to the engine combustion chamber 5 via the first intake valve 7. As described above, this first intake passage 12 is formed as a straight hole extending straight, and a fuel injection valve (fuel injector) 2+ is disposed on the earthen wall of the first intake passage 12. Fuel is injected from the fuel injection valve 21 toward the back surface of the umbrella portion of the first intake valve 7.

By the way, the second and third intake passages 13.14 are connected to each of the first to fourth cylinders No.1 to No.1, for example, as shown in FIG.
o4 of mutually adjacent cylinders (N.

The third intake passage 14 of the first cylinder, the second intake passage 13 of the NO2 cylinder, the third intake passage 14 of the No. 2 cylinder, the second intake passage 13 of the No. 3 cylinder, and the third intake passage 14 of the No. 3 cylinder. The second intake passages 13) of the No. 4 cylinder are formed in a common boat section (Siamese type) 16 that communicates with each other on the upstream side of the intake boat section.

An intake control valve 19 for forming a swirl is disposed in the common boat section 16, and is controlled to open and close by external control means in accordance with the operating state of the engine. Further, the direction of incidence of the first intake passage 12, which is the center port, into the engine combustion chamber 5 is set in the direction of the spark plug 6 at the center of the cylinder pore.

In the engine of this embodiment having the above structure, for example, during partial load operation, only air flows into the combustion chamber 5 during the first half of the intake stroke.
While the fuel is supplied to the fuel injector 21 in the latter half of the intake stroke,
operates to supply injected fuel into the combustion chamber, thereby forming an ia'tfJi air-fuel mixture near the spark plug 6 at the top of the combustion chamber, while a lean air-fuel mixture is formed below the combustion chamber. A layer is formed, and the air-fuel mixture in the combustion chamber is stratified. As a result, the rich air-fuel mixture gathers around the spark plug 6, improving ignition performance. Further, in this region, the intake control valve 19 is closed and the intake passage (N
Second intake passage 13 for o1 cylinder and NO3 cylinder. l
3 and the third intake passage 14 for the No. 2 cylinder and the No. 4 cylinder.
Since a swirl is generated in the combustion chamber 5 of each cylinder by the air flow flowing in from 14), the blue flame can be rapidly propagated into the combustion chamber 5. The combustion condition becomes even better.

Moreover, in the configuration of the above embodiment, the intake boat portions (side ports) between the first to fourth cylinders No. 1=No.
6, and each of these intake boats (third intake port 14 for No. 1 cylinder, second intake port 13 for No. 2 cylinder, third intake port 14 for No. 3 cylinder, No. 4
The second intake ports 13) of the cylinders are each opened toward the center of the cylinder bore of the engine combustion chamber 5. Therefore, there is no collision between the intake air in the second intake passage 13 and the third intake passage I4 of each cylinder, and the first intake passage (
It is possible to prevent the fuel supplied from the boat 12 from adhering to the unlink wall in the form of droplets, and it is also possible to improve the mixing performance of the air-fuel mixture over a wide operating range.

In addition, by making the intake passage common, the horizontal arrangement space of the intake system becomes smaller, and the diameter of the first intake passage 12, which is a fuel supply boat, can be increased, and at the same time, the engine itself can be made more compact. It becomes possible to achieve this goal.

Further, the common boat portions 16, 16 formed in this way
．． 16 to install the intake control valves 19, two intake control valves are sufficient for four cylinders, as shown in FIG.

In the configuration of the first embodiment, the first intake passage 12, which is the center port, is connected to the second and third intake passages, which are the side ports.
Intake passage 13. 1 and 4, and the spark plug 6 is located at the center of the top of the cylinder bore, as shown in FIGS. 3 and 4, for example. The first intake passage 12 equipped with the fuel injection valve 21 is opened from the upper part of the opposite side toward the center of the cylinder bore to provide the first intake valve 7, and the spark plug 6 is connected to the two side ports. It is also possible to change the configuration to a configuration in which it is installed closer to the side wall of the cylinder bore on the side opposite to the exhaust valve between the second and third intake passages 13 and 14.

According to such a configuration, the width of the parallel arrangement between each intake passage can be further narrowed without changing the relationship between the intake side inflow direction of the first intake passage 12, which is a fuel supply port, and the spark plug 6. As a result, the engine intake system of the -layer can be made more compact, and the diameter of the first intake passage 12 can be increased, thereby further reducing fuel adhesion to the wall surface.

In the above embodiment, the adjacent intake passages between each cylinder are made common, and an intake control valve for forming a swirl is provided in the common intake passage, but the structure of the above embodiment In this case, since the port portion of the common intake passage faces toward the center of the cylinder bore, the mixing performance of the air-fuel mixture is relatively high as described above. Therefore, even if no swirl is formed, the combustibility during low load operation will be good. Therefore, it is not necessary to provide the above-mentioned intake control valve.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of an intake system for a multi-valve engine according to a first embodiment of the present invention, FIG. 2 is a schematic horizontal sectional view of the same device, and FIG. 3 is a second embodiment of the present invention. FIG. 4 is a vertical cross-sectional view showing the configuration of the intake device of the multi-valve engine according to the embodiment.
The figure is a horizontal sectional view similar to FIG. 2. 1...Engine body 2...7 cylinder block 3...piston 4...cylinder head 5...engine combustion chamber 6...spark plug 7 ・ ・ 8 ・ ・ 9 ・ ・ 10 ・ l 1 ・12 ・ 13 ・ l 4 ・ 16 ・ 21 ・ ・First intake valve ・Second intake valve ・Third intake valve ・First exhaust valve ・Second exhaust valve ・First intake passage (first (intake boat), 2nd intake passage (2nd intake boat), 3rd intake passage (3rd intake boat), common boat section, fuel injection valve Figure 1 ψ engine body, 7 cylinder block piston / cylinder head engine combustion chamber spark plug first intake valve second intake valve third intake valve first exhaust valve second exhaust valve 14 third intake passage ( 3rd intake boat) 16...
Common port part 21...Fuel injection 1 (valve

Claims (1)

[Claims] 1. A center port provided in the center of each cylinder in the cylinder arrangement direction, two side ports provided on both sides of the cylinder arrangement direction with the center port in between, and a fuel injection valve provided in the center port. In the multi-valve engine, the side ports adjacent to each other between the cylinders are formed into a common port that communicates with each other, and the spark plug is located on an extension of the central axis of the center port. Intake system for a multi-valve engine.