JPH086596B2 - Multi-cylinder engine intake system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an intake system for a multi-cylinder engine which utilizes the dynamic effect of intake air to improve output.

[0002]

2. Description of the Related Art Conventionally, in an intake system of an engine, a negative pressure wave (a pressure wave of negative pressure) generated with the start of intake is reflected and inverted at the open end to the atmosphere on the upstream side of the intake passage or the intake expansion chamber to be positive. Utilizing the fact that a pressure wave (pressure wave of positive pressure) is returned to the intake port direction, the positive pressure wave reaches the intake port just before the intake valve is closed and pushes the intake air into the combustion chamber. It is known to increase the charging efficiency of the intake air by the inertia effect of. When such a technique is used, if the shape of the intake passage is constant, the vibration cycle of the pressure wave generated in the intake passage and the opening / closing cycle of the intake valve are matched to enhance the intake inertia effect. Limited to specific rotation range.

Therefore, in the past, Japanese Patent Laid-Open No. 56-11581 has been used.
As disclosed in Japanese Patent Publication No. 9, the length of the intake passage is changed according to the number of revolutions of the engine. For example, the intake passage for each cylinder is bifurcated in the upstream portion to form a long passage and a short passage. And the upstream ends of these passages are opened to the intake expansion chamber and the like, and a control valve is provided in a short passage so that the effective length of the intake passage is shortened by opening this control valve in the high rotation range. (See FIG. 6 of the above publication) is proposed, and according to the intake system of the engine, the inertial effect of intake can be enhanced in the low rotation range and the high rotation range.

[0004]

However, in the conventional structure described above, the short passage (communicating passage) is used in spite of attempting to improve the output by utilizing the pressure oscillation of the intake system.
Since no consideration has been given to the problem of reduction in filling efficiency due to the intake system layout such as the control valve and control valve, it is a layout that secures a high output by the dynamic effect of intake in the low rotation range and the high rotation range, There is a limit to the improvement of the filling efficiency, and there is a problem that the sufficient output cannot be achieved.

In view of the above, it is an object of the present invention to smooth the flow of pressure waves and further improve the filling efficiency simply by changing the layout of the control valve and the communication passage.

[0006]

In order to achieve the above-mentioned object, the invention of claim 1 is such that a first volume chamber and a second volume chamber provided in an intake system of an engine and a curve from the first volume chamber. And an independent intake passage connected to a corresponding cylinder of the engine, a communication passage branched and extended from each independent intake passage to communicate each independent intake passage with the second volume chamber, and to each communication passage. And a control valve that is opened / closed so as to open / close each communication passage in accordance with an operating state of the engine, and each independent intake passage and each communication passage intersect at an acute angle, and the control valve opens the valve. The state is set to be substantially parallel to the extending direction of the communication passage.

According to the invention of claim 2, the control valve according to claim 1 is opened / closed in accordance with the engine speed as an operating state of the engine, and the communication passage is closed in the low engine speed range and the high engine speed range. Will open and close the communication passage. Further, according to the invention of claim 3, the control valve according to claim 2 is adapted to be opened and closed only in a region where the engine load is equal to or higher than a predetermined load.

Further, in the invention of claim 4, the above-mentioned claim 1
3 to 3, it is assumed that the fuel injection valve is arranged at the inside of the curved portion of the independent intake passage. Further, in the invention of claim 5, in the above-mentioned claims 1 to 4, the throttle valve is arranged in the intake system on the upstream side of the first volume chamber.

[0009]

As a result, according to the first aspect of the invention, the control valve opens and closes according to the operating state of the engine, and when the control valve is closed, each cylinder communicates with the first volume chamber through the corresponding independent intake passage. On the other hand, when the control valve is opened, each cylinder communicates with the second volume chamber through the corresponding independent intake passage and the communication passage branched from the middle thereof, so that the dynamic effect of intake is obtained over a wide operating range. Therefore, the output can be improved. At that time, the inflow of the pressure wave can be achieved only by defining the acute-angled intersections of the independent intake passages and the communication passages and the opening direction of the control valve to be substantially parallel to the extending direction of the communication passages. The resistance can be lowered and the filling efficiency can be effectively improved.

According to the second aspect of the present invention, the control valve is opened / closed in accordance with the engine speed, and the communication passage is closed in the low rotation speed region of the engine, and the communication passage is opened in the high rotation speed region of the engine. The output is improved by the intake dynamic effect in the low speed region and the high speed region while improving the engine. In this case, according to the third aspect of the present invention, the control valve is opened and closed only in the region where the engine load is equal to or higher than the predetermined load.

Further, according to the invention of claim 4, since the fuel injection valve is arranged at the inside portion of the curved portion of the independent intake passage, the intake system can be made compact while exhibiting the effect of the invention of claim 1. be able to. Further, according to the invention of claim 5, since the throttle valve is arranged in the intake system on the upstream side of the first volume chamber, there is no throttle valve for inhibiting the propagation of the pressure wave in the propagation path of the pressure wave. The inflow resistance of waves can be further reduced.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings.

1 to 4 show an embodiment in which the present invention is applied to a 4-cylinder 4-cycle engine. In the figure,
Reference numeral 1 denotes an engine body including a cylinder block 2 and a cylinder head 3, and the like. The engine body 1 has first to fourth four cylinders 4, 4, ... Each cylinder 4 has a combustion chamber 5
Are formed.

Reference numeral 6 denotes an independent intake passage provided independently of each other for each cylinder, and each independent intake passage 6 is formed in the cylinder head 3 and constitutes an intake port forming a downstream end portion of the independent intake passage 6. It opens to the combustion chamber 5 of each cylinder 4 via 7. The reference numeral 8 designates an intake expansion chamber composed of a substantially rectangular tubular tank extending parallel to the longitudinal direction of the engine. The intake expansion chamber 8 is vertically partitioned by a partition plate 9 and has a relatively large volume on the upper side. It is divided into a volume chamber 8a and a second volume chamber 8b having a relatively small volume on the lower side. The upstream ends of the independent intake passages 6, 6 ... Are connected to the first volume chamber 8a of the intake expansion chamber 8 with substantially the same passage length. An intake air introducing pipe 10 for introducing outside air is connected to one end surface of the first volume chamber 8a, and a throttle valve 11 for controlling an intake air amount is provided in the intake air introducing pipe 10.
The intake air introduced into the first volume chamber 8a by the intake introduction pipe 10 is supplied to the combustion chamber 5 of each cylinder 4 through each independent intake passage 6. An intake valve 12 is provided in the intake port 7.

Further, a second passage 13 as a communication passage branches and extends from an intermediate point of each of the independent intake passages 6,
The other ends of the respective second passages 13, 13 ... Are connected to the second volume chamber 8b of the intake expansion chamber 8 with substantially the same passage length, whereby the second volume chamber 8b and each second volume chamber 8b are connected.
.. communicate with each other by the passage 13. In this case, as shown in FIG. 1, the second passage 13 joins the independent intake passage 6 at an acute intersection angle.

A butterfly type shutter valve 14 as a control valve for opening and closing the second passage 13 is provided near the opening of each second passage 13.
Each shutter valve 14 is rotatably supported by a valve shaft 15 extending parallel to the longitudinal direction of the intake expansion chamber 8. In this case, as shown by the alternate long and short dash line in FIG. 1, one end of the shutter valve 14 advances into the independent intake passage 6 while the other end of the shutter valve 14 retreats into the second passage 13 and Are provided so as to be located on the downstream side of the rotation axis of the shutter valve 14 in the intake air inflow direction. Since the shutter valve 14 is provided in this way, intake air flowing through the independent intake passage 6 flows downstream along the surface of the butterfly shutter valve 14 on the independent intake passage side, so that one end of the shutter valve 14 is opened when the valve is opened. Despite advancing into the independent intake passage 6, the increase in intake resistance can be suppressed as much as possible.

Although not shown, each shutter valve 14 is controlled to be opened / closed via an actuator by a control circuit that receives an output of an engine speed detecting means or the like, and each independent intake passage 6 by the second volume chamber 8b. , 6 ... Controls communication between each other according to the engine operating state, and is controlled so as to be closed in a low speed range where the engine speed is less than a set value and opened in a high speed range where the engine speed is higher than the set value. It It should be noted that the opening / closing operation of the shutter valve 14 according to the engine speed as described above may be performed at least during high load when output is required, and when the load is low, the shutter valve 14 is opened or closed. It may be kept.

In such an intake system, 16 is the intake expansion chamber 8 and each of the independent intake passages 6 and 6.
, And each of the second passages 13, 13 ..., which is an intake system structure, and the structure 16 is a tank that constitutes the intake expansion chamber 8 (first volume chamber 8a and second volume chamber 8b). The part 17 and a part of the constituent wall, that is, the side wall and the lower wall of the tank part 17, extending from the upper side of the tank part 17 opposite to the engine side to the side and the lower side by detouring and curving around the periphery of the tank part 17. The upstream side portions 6a, 6a of the respective independent intake passages 6, 6 ...
Integral intake pipe parts 18, 18 ... Formed integrally so as to open to the upper side of the volume chamber 8a) and the respective integrated intake pipe parts 1
Branch intake pipe portions 19, 19 ... Branching and extending from the lower side of the engine 18 toward the engine side for each cylinder to form the downstream side portions 6b, 6b ... Of the independent intake passages 6, 6 ,.
In the vicinity of the branch intake pipe portion 19 of each integral intake pipe portion 18, the lower wall of the constituent walls of the tank portion 17 (second volume chamber 8b) is utilized to make the middle of each independent intake passage 6 a second volume chamber 8b
Communication pipe part 2 integrally forming a second passage 13 communicating with the
0, 20 ... and a flange portion 21 connecting the tip end portions of the respective branch intake pipe portions 19, 19 ... to each other, and each branch intake pipe portion 1 with respect to the engine body 1 by the flange portion 21.
With the independent intake passage downstream side portion 6b of 9 aligned with the intake port 7 of each cylinder 4, the bolts 22, 22 ... Are laterally inserted and tightened to be fixed to the engine body 1. The upper part of the side of the tank portion 17 on the engine side is formed so as to bulge toward the engine side to ensure a sufficient volume of the first volume chamber 8a.

Further, the independent intake passage downstream side portion 6b of each branch intake pipe portion 19 and each intake port 7 extend in a substantially straight line from obliquely above toward the combustion chamber 5 and open into the combustion chamber 5. Has been formed. An injection valve mounting hole 23 is formed in an upper portion of the branch intake pipe portion 19 near the downstream end of the downstream side portion 6b of the independent intake passage and inward of the curved portion of the independent intake passage. The tip injection port is inserted into and fixed to the mounting hole 23 via the seal ring 23a. The mounting hole 23 and the fuel injection valve 2
4 is mounted so that fuel from the injection valve 24 is injected toward the intake valve 12 of the combustion chamber 5, and the fuel injection valves 24, 24 ... Are arranged parallel to the longitudinal direction of the engine. The fuel supply pipe 25 is connected and connected. As a result, the fuel injection valve 24 is mounted in a lying state substantially along the branch intake pipe portion 19, and the intake expansion chamber 8 (tank portion 17 is provided on the extension line 1 of the center line of the fuel injection valve 24). ) Is located close to the fuel injection valve 24 and the fuel supply pipe 25.

Further, the second passage 13 of each of the communicating pipe portions 20.
Is provided with the shutter valve 14, and the intake expansion chamber 8 (tank portion 17) is provided with a center extension line l of the fuel injection valve 24.
Since it is located above, the intake system structure 16 has the intake expansion chamber 8 in the tank portion 17 at a position lower than the center extension line 1 and including the second passages 13, 13.
Of the second volume chamber 8b and the first volume chamber 8 of the intake expansion chamber 8
It is formed by dividing the upper and lower parts of the tank part 17 and each integral intake pipe part 18 at a position of the partition plate 9 between a and a by a dividing surface along the longitudinal direction of the intake expansion chamber 8. , 18 ... Upper half 1 integrally formed with the upper half part
6a, the lower half of the tank portion 17, the integrated intake pipe portions 18, 1
8 is composed of a lower half part, branch intake pipe parts 19, 19 ..., communication pipe parts 20, 20 ... and a lower part 16b integrally formed with a flange part 21, and both parts 16a, 16b.
Are joined via the partition plate 9, and the bolts 26, 26 ...
Are tightly connected by inserting from below and tightening.

Further, as shown in detail in FIG. 4, each of the second passages 13 is formed on the lower wall of the tank portion 17 (second volume chamber 8b).
Are integrally formed between the openings to the second volume chamber 8b and at both ends thereof so as to rotatably support the valve shaft 15 of the shutter valve 14, and the periphery of each of the openings, that is, the shutter. Rib portions 28, 28 ... Which are annularly raised so as to continuously connect the boss portions 27, 27 are integrally formed on the valve seat portion on which the valve body 14a of the valve 14 is seated. Intake expansion chamber 8 is formed by bosses 27, 27 ...
The rigidity of the (tank part 17) in the longitudinal direction of the engine is increased.

Further, as shown in FIG. 4, the second passage 13 is drilled from the second volume chamber 8b side by a drill, and the connection portion of the second passage 13 with the independent intake passage is smoothed.
Formed in the second portion 13 to suppress the change of the passage cross-sectional area of the second passage 13 to be small and gentle, and to prevent the flow resistance from the second volume chamber 8b to the independent intake passage 6 via the second passage 13 and its change. Is kept small. Further, 29 is a rib portion which is formed along the boss portion 27 and which connects the annular rib portions 28, 28 around the opening of the second passage 13 to each other.

Next, the operation of the above embodiment will be described. When the shutter valves 14 are closed and the second passage 13 is closed, the communication between the independent intake passages 6, 6 ... By the second volume chamber 8b is cut off. In this state, the negative pressure wave generated in the intake stroke of each cylinder 4 propagates to the first volume chamber 8a and is reflected there, that is, the negative pressure wave and its reflected wave propagate through a relatively long passage, so that the low pressure wave is reduced. The vibration cycle of such a pressure wave matches the intake valve opening / closing cycle in the rotation range, the inertia effect of intake air in the low rotation range is enhanced, and the intake charging efficiency is enhanced.

On the other hand, in a state where the respective shutter valves 14 are opened and the second passage 13 is opened, and the independent intake passages 6, 6 ... Are communicated with each other by the second volume chamber 8b, The negative pressure wave generated in the intake stroke is reflected by the second volume chamber 8b through the second passage 13 and the passage length used for propagating the negative pressure wave and the reflected wave is shortened. The inertial effect is enhanced, and the pressure wave propagating from other cylinders in this operating range also receives the second volume chamber 8b.
Thus, the filling efficiency in the high rotation range is significantly improved. Therefore, at least when the load is high, at a predetermined rotational speed corresponding to an intermediate rotational speed of each rotational speed at which the intake inertia effect of the low rotational speed and the high rotational speed is obtained,
By closing the shutter valve 14 on the lower rotation side and opening the shutter valve 14 on the higher rotation side than this, the intake charging efficiency can be increased and the output can be improved in the entire rotation range. In particular, the intake charge efficiency in the high engine speed range is further enhanced by the pressure propagation action between the cylinders, as compared with the conventional case where the intake passage is simply shortened to increase the inertia effect. .

Further, when the intake stroke ends and the intake valve 12 closes the intake port of the combustion chamber 5, the pressure wave is transmitted to the intake port 7 of the independent intake passage 6 by the propagation of the reflected wave, but the pressure wave is intaken. After being reflected by the valve 12, the second passage 1
3 and the second volume chamber 8b to be propagated and introduced into the independent intake passage 6 in the intake stroke. In this case, since the second passage 13 merges with the independent intake passage 6 with an acute angle of intersection, the pressure wave is transmitted from the independent intake passage 6 after the intake stroke to the middle of the independent intake passage 6. After being smoothly introduced into the second passage 13 that opens in the section, the second volume chamber 8b and the second passage 13 that opens in the middle of the independent intake passage 6 in the intake stroke smoothly into the independent intake passage 6 in the intake stroke. be introduced. Therefore, the pressure wave is efficiently transmitted to the intake port 7 of the independent intake passage 6, so that the intake charging efficiency is improved.

Incidentally, as the size of the first and second volume chambers 8a and 8b suitable for effectively exhibiting the above-mentioned action, the first volume chamber 8a has a capacity of 0.5 times or more of the displacement. It is desirable that the volume of the second volume chamber 8b be 1.5 times or less the displacement. Further, the second volume chamber 8b
It is desirable to make the volume smaller than that of the first volume chamber 8a, and make the cross-sectional area of the second volume chamber 8b larger than the cross-sectional area of each independent intake passage 6.

In this case, the intake expansion chamber 8 (the first volume chamber 8a and the second volume chamber 8b in the intake system structure 16).
), An integral intake pipe portion 18 that constitutes the upstream portion 6a of each independent intake passage 6, a branch intake pipe portion 19 that constitutes the downstream portion 6b of each independent intake passage 6, and each second passage. 13 and the communication pipe portion 20 constituting each unit 13, the individual intake passages 6 bypass the periphery of the intake expansion chamber 8 and are integrally formed by utilizing a part of the constituent wall of the intake expansion chamber 8 (tank portion 17). Since the second passages 13 are formed integrally with a part of the constituent wall of the intake expansion chamber 8 (second volume chamber 8b), the required length of the independent intake passage 6 and the intake air are increased. The first and second volume chambers 8a, 8 of the expansion chamber 8
In obtaining each required volume of b, these intake systems can be made compact and small, so that the required length and required volume can be sufficiently secured in a limited space (engine room). Therefore, the vehicle mountability can be improved.

Further, in this case, the fuel injection valve 24 is close to the downstream end of the branch intake pipe portion 19, that is, the downstream side of the independent intake passage 6, and the injected fuel is atomized with good responsiveness to the combustion chamber 5. The tank portion 17 (the intake expansion chamber 8) of the intake system structure 16 is located close to the center extension line 1 of the fuel injection valve 24 because it is mounted toward the combustion chamber 5 to be supplied. , And it is necessary to dispose the shutter valve 14 in each of the second passages 13. Therefore, the intake system structure 16 in the tank portion 17 is located below the center extension line 1, that is, on the side of the branch intake pipe portion 19 and at the position of the partition plate 9 along the longitudinal direction of the intake expansion chamber 8. Upper divided body 16a and lower divided body 1 vertically
6b and the two divided bodies 16a, 16b are joined together via the partition plate 9, so that the lower divided body 16b is attached to the engine body 1 by the flange portion 21 of the bolt 2 from the side.
After mounting by tightening with 2, the lower divided body 16
Each fuel injection valve 24 is attached by inserting the fuel injection valve 24 into the injection valve mounting hole 23 of each branch intake pipe portion 19 of b from the direction of the center extension line 1 and fixing the fuel supply pipe 25 to the lower split body 16b. At the same time, the shutter valve 14 is inserted into the second passage 13 of each communication pipe portion 20 of the lower divided body 16b from above.
Is fixed to the valve shaft 15, and then the upper divided body 16a is joined to the lower divided body 16b with the partition plate 9 interposed therebetween, and the bolts 26 are tightened from below so that both 16a and 16b are joined together. By integrally connecting the shutter valve 14 and the fuel injection valve 24, it is possible to secure good moldability and easily assemble the upper and lower split bodies 16a and 16b. Can be performed easily, and good assembling property can be secured.

Moreover, since the upper divided body 16a and the lower divided body 16b are coupled by tightening the bolts 26 from below, the tank portion 17 is secured as described above while ensuring good assembling. There is also an advantage that a bulge can be formed in the upper portion of the side of the (intake expansion chamber 8) on the engine side, and a sufficient volume of the intake expansion chamber 8, especially the first volume chamber 8a, can be secured. The second volume chamber 8b is arranged in parallel with the first volume chamber 8a by vertically dividing the tank portion 17 of the intake system structure 16 by the partition plate 9, and a part of the wall of the first volume chamber 8a. Since the (partition plate 9) is formed in common, the intake system can be made more compact.

Further, the tank portion 17 (second volume chamber 8)
The lower wall of b) is integrally formed with boss portions 27, 27 ... Which rotatably support a valve shaft 15 extending in parallel to the longitudinal direction of the engine to which the valve body 14a of each shutter valve 14 is fixed. The bosses 27, 27 ... Are annular ribs 2 integrally formed around the opening of each second passage 13.
.. are connected in series, the rigidity of the intake expansion chamber 8 (tank portion 17) in the longitudinal direction of the engine is increased. Therefore, the vibrational deformation of the tank portion 17 due to the engine vibration is suppressed as much as possible, and the smooth opening / closing operation is stably ensured without interfering with the opening / closing of the shutter valve 14 as in the conventional case. Therefore, it is possible to ensure the above-mentioned intake inertia effect. Further, by integrally forming the boss portion 27 and the rib portion 28 on the constituent wall of the tank portion 17, the structure can be made compact and simplified.

It is needless to say that the present invention is not limited to the four-cylinder engine as in the above embodiments, but can be applied to other multi-cylinder engines, for example, a five-cylinder engine and a six-cylinder engine.

[0032]

As described above, according to the inventions of claims 1 to 5, it is possible to effectively improve the charging efficiency over a wide operating range by simply changing the layout, and to effectively improve the output. It can be.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view taken along the line I-I of FIG. 3, showing an intake system for a multi-cylinder engine according to an embodiment of the present invention.

FIG. 2 shows the intake system of the multi-cylinder engine, which is shown in FIG.
It is a vertical side view in the II-II line.

FIG. 3 is a plan view in which a part of the intake device of the multi-cylinder engine is cut away.

FIG. 4 shows the intake system of the multi-cylinder engine, which is shown in FIG.
FIG. 4 is an enlarged sectional view taken along line IV-IV.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Engine main body 4 ... Cylinder 6 ... Independent intake passage 8 ... Intake expansion chamber 8a ... 1st volume chamber 8b ... 2nd volume chamber 13 ... 2nd passage 14 ... Shutter valve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Hanafusa 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (56) References: Actual Development Sho 53-4007 (JP, U) JP 58- 46668 (JP, B2)

Claims (5)

[Claims] 1. A first volume provided in an intake system of an engine
Curved and extended from the chamber and the second volume chamber and the first volume chamber.
And independent intake passages connected to the corresponding cylinders of the engine
And branch and extend from each of the independent intake passages and
A communication passage that communicates with the second volume chamber, and each communication passage that is provided in each communication passage,
And a control valve that opens and closes so as to open and close the communication passage, wherein the independent intake passages and the communication passages intersect at an acute angle.
In the open state of the control valve, how the communication passage extends
It is set so that it is almost parallel to the direction
Intake device for multi-cylinder engine. 2. The control valve is for operating the engine.
Open and close depending on the engine speed,
Close the communication passage in the rolling range and open the communication passage in the high rotation range.
2. The opening / closing operation according to claim 1.
Intake device for multi-cylinder engine. 3. The engine load of the control valve is a predetermined load.
The opening / closing operation is performed only in the above range.
Intake device for multi-cylinder engine. 4. An inward portion of the curved portion of the independent intake passage.
A fuel injection valve is disposed in the
Intake device for a multi-cylinder engine according to any one of 1 to 3
Place. 5. An intake system upstream of the first volume chamber
A throttle valve is arranged.
An intake device for a multi-cylinder engine according to any one of 1 to 4.
Place.