JPS5852334Y2 - engine intake system - Google Patents

Description

[Detailed description of the invention] This invention opens a low-load intake passage and a high-load intake passage that are independent of each other in the combustion chamber of each cylinder that constitutes a multi-cylinder engine. , relates to an improvement in a so-called multiple intake system that supplies air-fuel mixture only through the low-load intake passage, and when the engine is under high load, the air-fuel mixture is supplied from the high-load intake passage in addition to the low-load intake passage. It is something.

Traditionally, this type of dual intake device has been well known.
In particular, when the engine is under low load, a small amount of air-fuel mixture can be squeezed through the low-load intake passage, so the air-fuel mixture flow speed can be increased compared to the case of a single intake passage, and the fuel flow rate can be increased. In addition to promoting vaporization and atomization, it is also possible to directively flow the air-fuel mixture at a high flow rate into the combustion chamber, creating a large swirl, which improves engine combustibility and fuel efficiency. This has the advantage of improving emission performance.

One form of the above-mentioned dual intake system is one in which the low-load intake passage and the high-load intake passage are completely independent from the carburetor as a fuel supply device to the combustion chamber. In this type of dual intake system, air-fuel mixture is not supplied to the high-load intake passage when the engine is under low load. When the throttle valve of the high-load carburetor is opened from the fully closed state when it is almost fully open,
The air that had accumulated in the high-load intake passage is suddenly supplied into the combustion chamber, causing the air-fuel mixture to become overlean and combustibility in the combustion chamber to temporarily deteriorate, especially if the engine has not warmed up completely. In this case, there was a problem that knocking occurred.

This is because, in the dual intake system as described above, the high-load intake passage is independent over the entire length of the passage from just downstream of the high-load carburetor to the combustion chamber, so the volume of the high-load intake passage is smaller than the engine. This is due to the fact that it exists as a complete dead volume during low load.

In order to solve this problem, the intake passage downstream of the carburetor is provided with a common intake passage connected to the carburetor and a first intake passage connected to the common intake passage and each independently opened into the combustion chamber.
It consists of a branch intake passage and a second branch intake passage, and the second branch intake passage is provided with an auxiliary valve that closes when the engine is under low load and opens when the engine has high load.When the engine is under low load, the common intake passage and the first branch A dual intake system is used in which the air-fuel mixture is supplied only through the intake passage, and when the engine is under high load, the air-fuel mixture is supplied through the common intake passage and the first and second branch intake passages. It is possible to reduce the dead volume that exists when the engine is under low load by making the length of the intake passage through which the air-fuel mixture does not flow as short as possible.

The present invention relates to the arrangement structure of the first and second branch intake passages that are formed independently downstream of the common intake passage that continues downstream of the carburetor, and more specifically to the connection structure with the common intake passage. The second branch intake passages used during high-load operation of the engine are gathered together for adjacent cylinders and connected to the common intake passage in almost a straight line, and an auxiliary valve is disposed in this gathering part. To provide an engine intake device that adopts a connection structure in which a branch intake passage is curved and connected to a common intake passage, and can enhance the responsiveness of fuel (mixture) supply especially during high-load operation of the engine. The purpose is to

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

In FIG. 1, E represents a cylinder body (not specifically shown).

) and the cylinder head 1, the crankshaft axis L
The engine body has a total of four cylinders C1 to C4 lined up along the IfC, and the cylinder head 1 has four cylinders C1 to C4 lined up along IfC.
Intake ports 21 to 24/C that open to the combustion chambers of □ to C4
On the one hand, each exhaust port 4□~44 opens into the combustion chamber on the other side, and has an internal intake passage 3, ~34 leading to the side surface 1 on the other side.
It has internal exhaust passages 5□ to 54 that reach b.

On the other hand, IM has a low load carburetor 6p and a high load carburetor 6p.
The intake manifold is made of a cast product that distributes and supplies the air-fuel mixture supplied by the multiple carburetor 6 connected to the air-fuel mixture to each cylinder C□ to C4. Align the mounting flange 7 formed on the side surface 1aK of the cylinder head 10, and then tighten the bolts (
Not shown.

) is supported in a fixed state on the cylinder head 1.

This intake manifold IM supports the dual carburetor 6 at the top, and has a gathering part 9 inside that communicates in common with the low-load intake passage 8p and the high-load intake passage 8s of the carburetor 6 directly below the carburetor. The formed thick center support part 10 and the center support part 10 also protrude to the left and right in the figure and largely go around the cylinder head 1 side, forming a common intake passage 11, 12 communicating with the gathering part 9 inside. A pair of tube wall portions 13, 14, a passage width gradually widening continuously from the tip of each tube wall portion 13, 14, and a pair of separation walls 16a inside.
, 16b; 17a, 17b, a pair of symmetrical branch walls 1B, 19, and a pair of branch walls 18.
.

The pair of branch wall parts 18 and 19 are respectively connected to the pipe wall part 1.
3 and 14, and is substantially continuous with the joint surface 1 of the cylinder head 1.
A is a pair of left and right separation walls 1 formed perpendicular to g.
6a, 16b; 17a, 17b, continuous in the tangential direction downstream of the common air supply passages 11, 120, as a gathering part of the common second branch intake passage that smoothly communicates in a straight line; The second branch intake passage 20 of
, 21 and each separation wall 15 a , 16 b ; 17
Openings 22a and 22b opened at the connecting portions of a and 17b with the pipe wall portions 13 and 14; communicate with the common intake passage 11.12 through openings 23a and 23b, respectively, and each separation wall 16
a.

16b; 17a t outside KJ of 17b! Each pair of first branch intake passages 24a are curved 5IC so as to penetrate into the iu
, 24b; 25a, 25b are formed therein.

On the other hand, the internal intake passage 3□~ formed in the cylinder head 1
34 is adapted to the intake passage structure of the above-mentioned intake manifold IM, and the two internal intake passages 3□, 3° on the left side of the figure and the two internal intake passages 33° and 34 on the right side in the figure are paired, respectively.
Each branch wall portion 18, 1 of the symmetrical intake manifold IM
They are formed to be left-right symmetrical with respect to each of the symmetry center lines P1 and P2 of 9.

That is, each internal intake passage 31 to 34 is connected to each separation wall 16.
a, 16b; 17a, 17bVc Each continuous partition wall 27
a, 27b; each intake port 2□ by 28a, 28b
~ 24, the first branch internal intake passages 29a, 29b; 30a have a small passage cross-sectional area.

30b, and the second branch internal intake passage 3 with a large direct passage cross-section.
1a, 31b; 32at32b, and each first branch internal intake passage 29a, 29b; 30a.

30 First branch intake passage 24 of the old intake manifold IM
a, 24b; 25a, 25b, respectively.

Moreover, each second branch internal intake passage 31a. 31b, 32a
, 32bt-c Two second branch internal intake passages 31 on the left side
a, 31b communicate in a straight line with the common second branch intake passage 20 of the left branch wall 18, and the two right second branch internal intake passages 32a, 32b communicate with the common second branch intake passage 20 of the left branch wall 18. 19 common second branch intake passages 21,
The structure is such that they communicate in a straight line.

In addition, each passage 20° 24a of the branch wall portions 18 and 19
, 24b; 21. The midway cross-sectional shape of 25a and 25b and the opening shape in the mounting flange 7 are as shown in FIGS. 5 and 3, respectively.

As a result of the above intake manifold IM and the intake passage configuration of the cylinder head 1, the intake passages from the downstream gathering part 9 of the multiple carburetor 6 to the intake ports 2□ to 24vc of each cylinder C1 to C4 are the common intake passages 11 and 12. and each common intake passage 11
, 120 downstream of each common intake passage 11, 12Vc
A pair of left and right first branch intake passages 33 a , 33 b ; 34 a t with a small cross-sectional area of the passages connected by being curved relative to each other.
34b, and the common first branch intake passage 33a that is smoothly connected to the common intake passages 11 and 12VC in a straight line.

33 t) ; 34 a t 3 A second branch intake passage 35 a t 3 with a large passage cross-sectional area independent from 34 b
5 b; 36 a t36b.

Note that the second branch intake passages 35a, 35b, 36a
, 36b are connected to a common second branch intake passage 20., 36b.
21.

and each first branch intake passage 33a, 33b.

34 a t 34 b, and each second branch intake passage 35a
.

35 b, 36 a t 36 b means each partition wall 2
7a.

27b, 28a, 28bvC consecutively intake port 2□~
A partition member (described later) provided to partition 24 into a shell shape completely partitions off the intake valve immediately upstream of the fully closed intake valve.

On the other hand, as shown in FIGS. 1, 2, and 5, a pair of left and right separation walls 16a, 16b; 17a.

17b formed by a common second branch intake passage 20.
On the upstream side of 210, there are common second branch intake passages 20, 2.
Auxiliary valves 41, 4 each consisting of a butterfly valve that opens and closes 1, respectively.
2 are provided.

In this embodiment, since the auxiliary valves 41 and 42 are provided in the common second branch intake passage 20.degree. 21, there is an advantage that the number of required valves can be reduced to half the number of cylinders.

These auxiliary valves 41, 42+ are connected to the intake manifold IM.
A pair of left and right branch walls 1B and 19 are fixed using screws 45, respectively, to a pair of through shafts 43 and 44 which are rotatably penetrated and supported at four points so as to be parallel to the axis of the crankshaft. , the pair of through shafts 43 and 44 are connected to the pair of branch walls 18
A pair of coupling fittings 46, 47 in the space between and 19
, they are connected coaxially and have a common rotation axis 48.
form.

The pair of coupling fittings 46 and 47 are for absorbing misalignment between the pair of through shafts 43 and 44 that may occur due to machining errors, etc., and are provided at opposing shaft ends of the pair of through shafts 43 and 44, respectively. A spring 51 is connected between a pair of coupling fittings 46 and 47 which are fixed so as not to come off by a fixed oak) 49.50.
A pair of joining pieces 46a are joined together by a pair of joining pieces 46a and bent from respective joining fittings 46 and 47 so as to face each other.

47a are coupled by bolts 53 so as to rotate together.

In addition, in the figure, 54 is the coupling fitting 47 of the long side penetrating shaft 44.
A coil spring is compressed between the branch wall portion 19 and the inner outer wall surface of the branch wall portion 19 to restrict displacement in the axial direction.

This common rotating shaft 48 may be formed by a single shaft.

In any case, since the common rotating shaft 48 can be supported by a total of eight points, four points on each side, the support structure can be made strong.

Further, the rotating shaft 48 is connected to each first shaft in the intake manifold IM.
Branch intake passages 24a, 24b, 25a.

As shown in FIG. 4, the passage cross-sectional area caused by passing through the shaft 25b is reduced by curving the earthen wall in the portion through which the rotating shaft 48 passes upward convexly in advance. It is preferable to increase this to a certain extent so that it is substantially equal to the passage cross-sectional area of the portion through which the rotating shaft 48 does not penetrate.

A nut 56 is fixed to one end of the common rotating shaft 48 through a washer 55, while the rotating shaft 48 is operated to rotate at the other end when the engine is under high load, and a pair of auxiliary valves 41,
42 is coupled to an operating mechanism for opening.

As shown in FIGS. 1 and 2, this operating mechanism consists of a free end of a lever 58 fixed to the shaft end of a common rotating shaft 48 with a nut 5T, and a low-load throttle valve 59 of the multiple carburetor 6. A link rod 62 connects the free end of a bending lever 61 whose one end is rotatably fitted to the shaft end of the operating shaft 60 of the low-load throttle valve 59. An operating lever 65 is fastened and fixed to the collar 63 by a collar 64, and is provided with an engaging piece 65a that engages the bending lever 61 when the low-load throttle valve 59 is opened beyond the set opening degree.
When the low-load throttle valve 59 is opened beyond the set opening degree, that is, when the engine is under high load, the bending lever 61 is rotated counterclockwise in FIG.
The rotary shaft 48 is rotated through the rotary shaft 48, and the auxiliary valves 41 and 42 supported on the rotary shaft 48 are opened.

Note that the other end of the operating shaft 60 of the low-load throttle valve 59 is connected to an accelerator pedal (not shown).

) A well-known link mechanism (not shown) that interlocks with K.

) K connection, and is rotated in response to depression of the accelerator pedal.

Further, the operating lever 58, the link rod 62, and the bending lever 61 of the rotating shaft 48 are normally kept in the state shown in FIG. 2 by means of a return spring (not shown), that is, the auxiliary valves 41 and 42 are fully closed. held in position.

Next, the internal intake passages 3□ to 34 of the cylinder head 1 are
and each first branch internal intake passage 29a.

29b, 30at30b, and each second branch internal intake passage 3
1 a t 31 b t 32 a, 32 b, the above-mentioned partition wall 27 a t 27 b t 28 a
, 28 b tic will be explained about a partition/structure that continuously partitions the intake valve 70 directly above the fully closed state.

That is, as shown in FIG. 6, the partition plate T2 that continuously partitions the internal space above the intake valve 10 by the partition wall 27ac has a center portion in the width direction that is connected to the intake valve 10, as shown in FIGS. 8a and 8b.
Wing portions 12b are formed as a circular arc portion 72a that abuts on the outer periphery of the valve shaft portion 73, and on both sides in the vertical direction, continue from the circular arc portion 72a and widen on both sides with an opening angle of about 120° to 150°.

72c, and the side edges of the wing parts 72b, 72c are provided with flanges 72d, γ2e with constant width plate surfaces extending from the flanges 72d, 72et/C of the flat plate in FIG. 9a.

It is formed by inserting a slit groove 74a provided in the axial direction of a cylindrical pin 74 shown in FIG.

In this way, the cylindrical insertion portion 75 is formed using the cylindrical pin T4.

On the other hand, a fitting groove 76 provided in the cylinder wall corresponding to this insertion portion 75 is formed by drilling it into a cylindrical shape with a drill, as shown in FIGS. 1 and 6. Fitting groove 76.7 (l indicates insertion portion 75, γ5 of partition plate T2 assembled as shown in FIG. By press-fitting the valve seat 80 into a ring-shaped fitting portion 79 provided on the cylinder inner circumferential wall portion 78 forming the portion TI, the fitting groove 76°7 is formed.
6 is pressed and held from below, thereby fixing the entire partition plate 72 without wobbling.

Regarding the formation of the cylindrical insertion portion 75 of the partition plate T2, the flange 72d is a flat plate as described above.

A cylindrical pin T4 inserted with 72evC may be used, or a cylindrical insertion portion may be formed integrally with the flat plate, and although not specifically shown, the flange 72d of the flat plate,
A cylindrical insertion portion may be formed by forming 72e wide and bending it into a cylindrical shape.

The method in which the cylindrical pin T4 is inserted into the flat plate requires more parts than the one in which the flat plate and the insertion part are integrally formed, but the former is formed by cutting the flat plate and a round bar with a slit. The partition plate can be manufactured using the pins, and is easier to manufacture than the latter, which is a partition plate in which a flat plate and an insertion portion are integrally formed by drawing or bending.

In addition, the insertion portion T5 and the fitting groove 76 have a tapered shape that tapers in the axial direction, so that when the insertion portion 75 is pushed in the axial direction, the pushing force ensures a secure fitting state between the two. It may be possible to do so.

In the above-mentioned engine intake system, during low-load operation of the engine, the auxiliary valves 41 and 42 are fully closed, and the air-fuel mixture supplied from the low-load carburetor 6P is transferred to the common intake passage 1.
1, 12, each first branch intake passage 33a t33b
, 34a, 34b, which do not cause intake interference, and are introduced into the combustion chamber each time the intake valve 70 is opened.

In this case, the air-fuel mixture introduced into each cylinder C1 to C4 is passed through a first branch intake passage 33a with a small passage cross-sectional area;
33b.

34a, 34bI/c, and as a result of being introduced into the combustion chamber at a high flow velocity and with good directionality, &L large swirl is generated in the combustion chamber, and each spark plug q1. ... By igniting q4, it is possible to achieve good combustion and improve the combustibility of the engine during low load operation.

On the other hand, at the stage where the throttle valve 59 of the low-load carburetor 6P is opened beyond the set opening degree, the link operation mechanism
The auxiliary valves 41 and 42 are operated to open, and each second branch intake passage 3
Supply of the air-fuel mixture is also started from 5 a t 35 b > 36 a p 36 b.

The engine is shifted to high-load operation, and the high-load carburetor 6S
When the supply of air-fuel mixture is started from
A large amount of the air-fuel mixture supplied from S flows down the common intake passage 11°12, and a part thereof & the first branch intake passages 33a, 33b connected in a curved manner to the east common intake passage 11°12.
, 34a, 34b, most of the flow is connected smoothly to the common intake passages 11, 12 in a straight line.
b, 36a, and 36b smoothly.

Therefore, most of the air-fuel mixture is introduced into each combustion chamber with a smooth flow and responsiveness, and is introduced into each first branch intake passage 33a.

By weakening the air mixture flow introduced at a high flow rate from 33b, 34a, and 34b and weakening the swirl in the combustion chamber, the combustibility of the engine at this stage is improved and the output performance of the engine is improved.

In the embodiment detailed above, the common second branch intake passages 20 and 21 are formed in the intake manifold IM, but
Each second branch intake passage 35a, 35b.

In order to reduce the volumes of 36a and 36b as much as possible, the common second branch intake passage may be provided within the cylinder head 1.

In short, compared to the passage length t1 of the common intake passages 11 and 12,
Each second branch intake passage 35a, 35b, 36a.

The objective is to create a passage structure in which the passage length t2 of the passage 36b is as short as possible.

In the above embodiment, a dual carburetor 6 was used as the carburetor, but in this case, since the upstream of the intake passage is a common intake passage, the present invention is not limited to the dual carburetor 6, and for example, a venturi negative A variable venturi type vaporizer using pressure may also be used.

As is clear from the detailed explanation above, the present invention has an intake passage downstream of a fuel supply device that is branched into a common intake passage that is continuous with the fuel supply device, and a first and second intake passage that are independent of each other. In an engine intake system comprising a second branch intake passage, the second branch intake passage is provided with an auxiliary valve that closes when the engine is under low load and opens when the engine has high load, the common intake passage and the second branch intake passage. The second branch intake passages of adjacent cylinders are gathered together so that the second branch intake passages of the adjacent cylinders are connected to the common intake passage, and the auxiliary valve is interposed in the gathering part of the second branch intake passages connected to the common intake passage.
The present invention provides an engine intake device characterized in that a branch intake passage is connected to a common intake passage in a curved manner.

According to the present invention, since the common intake passage and the second branch intake passage are smoothly connected, the intake resistance of the second branch intake passage when the auxiliary valve is opened can be reduced.
The responsiveness of the air-fuel mixture (fuel) supply during high-load operation of the engine can be increased, and the output performance can be improved accordingly.

In addition, when the auxiliary valve is open, the second branch intake passage is straight, but the first branch intake passage is curved, so the air-fuel mixture in the first branch intake passage is weak and the combustion chamber is Combustibility is improved because the swirl is weakened.

In addition, in this invention, the second branch intake passages are grouped together for adjacent cylinders, so the number of auxiliary valves can be halved, and the structure of the intake manifold can be simplified, reducing dead volume when the engine is under low load. The volume of the second branch intake passage downstream of the auxiliary valve can be equalized, and torque imbalance between cylinders does not occur during operation when the auxiliary valve is opened.

[Brief explanation of drawings]

FIG. 1 is a horizontal cross-sectional view showing an intake system for a multi-cylinder engine according to an embodiment of the present invention, FIG. 2 is a side view of the intake manifold including a cross-section along the line ■-■ in FIG. 1, and FIG. is a front view of the intake manifold (with the rotating shaft and auxiliary valve removed), FIG. 4 is a sectional view taken along the line IV-IV in FIG. 1, and FIG. 5 is a sectional view taken along the line ■-■ in FIG. 1. , Figure 6 is the first
7 is a sectional view taken along the line ■-■ of FIG. 6, FIGS. 8 a and b are a plan view and a front view of the partition member of FIG. a, b are a plan view and a front view of the pin forming the insertion part of the partition member, respectively, FIGS. 10a, b
FIG. 2 is a plan view and a front view of the partition member with the pin attached thereto, respectively. 1...Cylinder head, 2□~24...
・Intake port, 6...Double carburetor, IM...
...Intake manifold, 11, 12--Common intake passage, 16a, 16b. 17a, 17b... Separation wall, 20, 21...
...Gathering part of the second branch intake passage, 33a, 33b, 3
4a. 34b...First branch intake passage, 35a t3
5b. 36 a t 36 b ””Second branch intake passage, 41
,42...Auxiliary valve.

Claims (1)

[Claims for Utility Model Registration] A common intake passage that connects the intake passage downstream of the fuel supply device to the fuel supply device, and first and second branches that are connected to the common intake passage and each independently open into the combustion chamber. In an engine intake system comprising an intake passage, and an auxiliary valve that closes when the engine is under low load and opens when the engine is under high load is interposed in the second branch intake passage, the common intake passage and the second branch intake passage; The auxiliary valve is interposed at the gathering part of the second branch intake passages connected to the common intake passage after converging the second branch intake passages of adjacent cylinders so that they form a substantially straight line; An intake system for an engine, characterized in that the intake passage and the first branch intake passage are curved and connected to each other.