JP2023005413A - intake manifold - Google Patents

Abstract

To further improve an intake manifold so that intake air flows in each of branch pipes as uniformly as possible while miniaturizing an intake main body, the intake manifold applying a distorted shape in which the intake main body is disposed in a manner of being deflected in a cylinder arrangement direction to the branch pipes.SOLUTION: An intake manifold includes a plurality of branch pipes 8A-8D having openings 41-44 for intake ports and one intake main body 8H communicated to basic end sides of the branch pipes. A shape of the intake main body 8H is a box shape long in an opening arrangement direction, a position in the opening arrangement direction of the intake main body 8H to the plurality of openings 41-44 is deflected, and an intake inlet i is formed on a side wall 8F at an upper side in a deflecting direction to the openings 41-44, of the intake main body 8H. The intake main body 8H is formed into a bulged shape so that a cross-sectional area of an inlet-side end portion 21 at a side of the intake inlet i in the longitudinal direction of the intake main body 8H becomes larger than cross-sectional areas of parts 22, 23 excluding the inlet-side end portion 21 of the intake main body 8H.SELECTED DRAWING: Figure 1

Description

The present invention relates to an intake manifold including a plurality of branch pipes having openings corresponding to respective intake ports, and one intake main body 8H communicating with the base ends of the plurality of branch pipes.

Intake manifolds used in industrial engines used in agricultural machinery, construction machinery, etc. and in automobile engines have a structure having a plurality of branch pipes and an intake main body (surge tank) communicating with the proximal end side of the branch pipes. There are also many intake manifolds with a branch pipe structure. For example, in a vertical inline four-cylinder engine, as disclosed in Patent Document 1, there are four branch pipes (branch pipes: 12 to 15) and one intake main body (surge tank : 11).

In the intake manifold (1) disclosed in Patent Document 1, each of the four branch pipes (branch pipes: 12 to 15) is a relatively long pipe, and the intake main body (surge tank tank: 11) is located at one point. The intake inlet (throttle device: 3) is provided at the end of the intake main body opposite to the side where the branch pipe is taken out. Therefore, the length and volume from the intake port of the intake main body (throttle device: 3) to the tip of each branch pipe (branch pipe: 12 to 15) can be made uniform, and the intake port of the cylinder head (each cylinder) It is assumed that the flow of intake air is relatively uniform.

On the other hand, depending on the model and specifications of the engine, the positional relationship between the intake main body and each branch pipe may be distorted. For example, in the engine shown in Patent Document 2, as shown in FIGS. 3 to 5, the intake body (surge tank: 14) is arranged in the cylinder arrangement direction (longitudinal direction of the cylinder head) with respect to the cylinder head (6). There is an intake inlet (see mounting flange 28 or throttle body 16) in the side wall on the biased upper side of the intake body, which is highly offset.

Therefore, the branch pipes (branch pipes: 46-1 to 46-4) are connected to the intake main body (surge tank: 14) with different inclination angles and different lengths, and The flow direction of the intake air from the intake main body to each branch pipe is angled opposite to the flow direction of the intake air at the intake inlet of the intake main body. In particular, in the first branch pipe (first branch pipe: 46-1) located at the upper end in the direction of deviation, the reverse angle is considerably steep.

Therefore, in the intake manifold shown in Patent Document 2, the length and volume from the intake inlet of the intake body (surge tank: 14) to the tip of each branch pipe (branch pipes: 46-1 to 46-4) are different from each other. As a result, it is particularly difficult for intake air to flow smoothly through the first branch pipe (first branch pipe: 46-1), and the flow of intake air to each intake port (each cylinder) of the cylinder head tends to be uneven.

Therefore, in Patent Document 3, which discloses an intake manifold similar to the intake manifold having a distorted shape shown in Patent Document 2, the tip openings of each of the four branch pipes (13) are arranged greatly biased in the arrangement direction. By making the intake main body (main pipe: 29) a large box shape that can increase the internal volume, the intake air from the intake inlet is configured to flow to each branch pipe in the same state as much as possible.

However, even with the intake manifold disclosed in Patent Document 3, it is possible to eliminate the tendency of the intake air to flow unevenly to each intake port, such as the fact that it is difficult for the intake air to flow through the first branch pipe, which has a particularly long length. In addition, there is a disadvantage that the intake main body tends to be large. Therefore, in the intake manifold having a distorted shape in which the intake main body is arranged in the direction of the cylinder arrangement, there is still room for improvement in terms of realizing a uniform flow of intake air in each branch pipe.

JP 2016-94841 A JP-A-11-50923 JP 2012-197759 A

An object of the present invention is to provide an intake manifold having a distorted shape in which the intake main body is arranged biased in the cylinder arrangement direction with respect to the branch pipes by further structurally devising the intake main body, while making the intake main body more compact. It is to be improved so that the intake air flows in each branch pipe as evenly as possible.

The present invention provides an intake manifold,
comprising a plurality of branch pipes having openings corresponding to respective intake ports, and one intake main body communicating with the proximal end sides of the plurality of branch pipes,
The shape of the intake main body is a box shape elongated in the opening arrangement direction in which the plurality of openings are arranged, and the position of the intake main body in the opening arrangement direction is biased with respect to the plurality of openings,
an air intake inlet is provided in a side wall on the upper side in a bias direction with respect to the opening of the air intake main body;
The air intake main body is arranged such that the cross-sectional area of the inlet side end on the side where the air intake inlet is located in the longitudinal direction of the air intake main body is larger than the cross-sectional area of the portion of the air intake main body other than the inlet side end. It is characterized in that it is set in a base bulging shape.

It is convenient that the first branch pipe located on the uppermost side in the direction of bias among the plurality of branch pipes is taken out from the inlet-side end, and the first branch pipe at the inlet-side end It is more expedient if the point of extraction of the air intake and the intake air inlet are set so as to be located laterally opposite one another. Further, the first branch pipe may be taken out with an inclination angle from the inlet side end toward the upstream side in the bias direction.

Regarding the present invention, refer to claims 5 to 11 for characteristic configurations and means other than the above-described configurations (means).

According to the present invention, although the details will be described later, due to the existence of the shape changing portion where the cross-sectional area is reduced from the inlet side end to the other portion, the internal space of the inlet side end is biased from the intake inlet (front and back). direction), it is possible to change the flow direction of the intake air to a large extent without difficulty, and it is possible to smoothly flow into the branch pipe on the most upstream side in the biased direction. In the other branch pipes, since the intake air flowing from the intake inlet in a biased direction (front-to-rear direction) is sufficiently spaced from the intake inlet, the intake air flows relatively smoothly.

Therefore, since the intake air from the intake inlet can flow smoothly and efficiently into the branch pipe which is located on the most upstream side in the direction of deviation and is particularly difficult for the intake air to flow, the intake body can be made compact without needlessly increasing its size. However, the flow to the plurality of branch pipes can be made equal to each other as much as possible.

As a result, the intake manifold, which has a distorted shape in which the intake main body is arranged biased in the cylinder arrangement direction with respect to the branch pipes, mainly by further structural improvements to the intake main body, has achieved a compact intake body while maintaining the branch pipes. It can be further improved so that the intake air flows as evenly as possible.

Left side view of intake manifold Right side view of intake manifold Bottom view of intake manifold (A) is a front view of the intake manifold, (B) is a rear view of the intake manifold Plan view of a cutaway part of the intake manifold Perspective view looking down on the intake manifold from the upper front left Plan view looking down on the industrial engine from the upper left Plan view looking down on the industrial engine from the upper left rear

EMBODIMENT OF THE INVENTION Below, the intake manifold by this invention and embodiment of the industrial engine to which it was applied are described, referring drawings. In the following, the side on which the transmission case 5 is provided in the crankshaft direction is the front, the side on which the flywheel housing 7 is provided is the rear, the side on which the intake manifold 8 is provided is the right, and the exhaust cover 10 is provided. left side.

FIGS. 7 and 8 show a spark-ignited vertical multi-cylinder (multiple) cylinder industrial engine E used in a work machine capable of traveling, such as an agricultural tractor or a lawn tractor. In this industrial engine E, a cylinder head 2 is assembled on the upper part of a cylinder block 1, a cylinder head cover (hereinafter simply referred to as a head cover) 3 is assembled on the upper part of the cylinder head 2, and a An oil pan 4 is assembled.

A transmission case 5 is assembled in front of the cylinder block 1 and a flywheel housing 7 is arranged behind the cylinder block 1 . 1A is a crankshaft, 6 is an engine cooling fan shaft (water pump shaft), 8 is an intake manifold, 9 is an alternator, and 10 is an exhaust cover. The exhaust cover 10 is a cover that covers an exhaust manifold (not shown) attached to the left side of the cylinder head 2 . The upper half of the cylinder block 1 is a cylinder part (notation is omitted), and the lower half is a crankcase (notation is omitted).

Four coil-integrated plugs 11 positioned on the right side of the head cover 3 and aligned in the front-rear direction are provided on the upper right side of the cylinder head 2 in a state of standing obliquely upward. The head cover 3 has a front upper wall 3a and a ceiling wall 3b slightly higher than the upper wall 3a on the rear side of the upper wall 3a. is provided with an oil cap 12. 7 and 8, 15 is a starter motor, 16 is a throttle body, 17 is a gas mixer, and 18 is a fuse box (engine-related accessory).

A front wall (notation omitted) of the ceiling wall 3b is provided with a blow-by gas lead-out portion 13 facing forward. A gas passage 14 is provided. The blow-by gas passages 14 are arranged behind the passage pipe 12A and after being bent substantially to the right (about 180 degrees) above the upper wall 3a, the foremost one 11 and the second from the front of the coil-integrated plug 11. It extends rightward through the front and back of the one 11 of .

Next, the intake manifold 8 and its peripheral structure will be described. As shown in FIGS. 1 to 6, the intake manifold 8 includes four (a plurality of examples) branch pipes 8A to 8D having openings 41 to 44 corresponding to the respective intake ports pa to pd of the cylinder head 2, It is provided with one intake main body (surge tank) 8H that communicates with the base ends of the four branch pipes 8A to 8D. That is, the intake manifold 8 has a so-called "branch pipe structure". The material of the intake manifold 8 is preferably a metal material such as an aluminum alloy, but may be made of other materials (synthetic resin material, etc.).

As shown in FIGS. 1 to 6, the intake main body 8H has a box shape elongated in the opening arrangement direction (the crankshaft direction and the front-rear direction) in which four openings 41 to 44 are arranged. It is configured to have a front inlet side end portion 21, a rear side counter-entrance side end portion 23, and an intermediate portion 22 between the front and rear. The opening arrangement direction, the cylinder arrangement direction, and the arrangement direction of the intake ports pa to pd are the same direction (front-rear direction).
The entrance-side end portion 21 has a vertically long rectangular shape when viewed in the front-rear direction, and includes a front wall (an example of a "side wall on the upper side in the biased direction") 8F, a front ceiling wall 24, a front left side wall 25, and a front right side wall. 26 and a front bottom wall 27 (see FIG. 4A). Note that the biased direction in this embodiment means the front-rear direction as shown in FIGS. 1 to 8. FIG. Further, the upper side in the bias direction means the front side in the front-rear direction.

The intermediate portion 22 has a vertically long cross-sectional shape when viewed in the front-rear direction, and has an intermediate ceiling wall 28 , an intermediate left side wall 29 , an intermediate right side wall 30 , and an intermediate bottom wall 31 .
The end 23 on the side opposite to the entrance has a rectangular shape slightly longer in the top and bottom than the left and right when viewed in the front-rear direction, and includes a rear wall (an example of the side wall at the other end in the longitudinal direction) 8R, a rear ceiling wall 32, and a rear left side wall 33. , a rear right side wall 34, and a rear bottom wall 35 (see FIG. 4B).

As shown in FIGS. 1 and 3, the intake main body 8H is positioned rearward (fourth opening 44 to the side). Specifically, the longitudinal length of the intake main body 8H and the longitudinal length of the first opening 41 and the fourth opening 44 are substantially the same, and the longitudinal position of the front surface 8f of the intake main body 8H is the same as the second opening. 1 opening 41 and the 2nd opening 42, and the position of the front-back direction of the rear surface 8r of the intake main body 8H is biased to the rear so that it is located behind the 4th opening 44. As shown in FIG.

As shown in FIGS. 1, 2, 4A, 5, and 6, the rear portion of the front left side wall 25 (corresponding to the "boundary portion between the inlet side end portion 21 and the intermediate portion 22") is The slanted side wall 8k is slanted toward the right as it goes rearward, that is, at an angle α (see FIG. 5) with respect to the front-rear direction. A rear portion 24a of the front ceiling wall 24 is formed as a sloped ceiling wall that slopes downward toward the rear (see FIG. 6). A rear portion 27a of the front bottom wall 27 is formed as an inclined bottom wall that is inclined upward toward the rear (see FIG. 2).

A flat front surface 8f is formed on most of the left side of the front wall 8F, projecting slightly forward from the rest of the front wall 8F (see FIGS. 2, 4A, and 6). A cylindrical intake inlet i is formed in the upper portion of the joint surface between the front surface 8f and the throttle body 16 and penetrates the front wall 8F in the front-rear direction. The intake inlet i is a hole for introducing mixed air from the throttle body 16 into the intake body 8H. Four nut portions n for bolting the throttle body 16 are formed around the intake inlet i (see FIG. 6). In addition, the intake inlet i is provided at a position slightly to the left (openings 41 to 44 side or cylinder head 2 side) of the center in the width direction of the front wall 8F (see FIG. 4A).

As shown in FIGS. 1, 5 and 6, a front portion 33a of the rear left side wall 33 (a boundary portion between the end portion 23 opposite to the entrance side and the intermediate portion 22) is inclined to the right as it goes forward. That is, the side wall (33a) is inclined at an angle β (see FIG. 5) with respect to the front-rear direction. On the outside of the rear wall 8R, mounting portions 20 for mounting the fuse box 18 described above are provided at two locations on the left and right. The mounting portion 20 is formed, for example, by a rearward projecting nut portion for bolting the fuse box 18 or its support, but other means may be used. A multi-purpose hole (circular hole) 37 is formed in the rear wall 8R for closing with a sealing plug 38 (see FIG. 5), mounting various sensors, and connecting passages. Holes 37 may be omitted.

As will be described below, the shape of the intake body 8H is set to a complicated shape such that the front and rear intermediate portions are narrowed. That is, the rear ceiling wall 32 and the intermediate ceiling wall 28 have the same vertical width (see FIG. 2), and the rear right wall 34, the intermediate right wall 30, and the front right wall 26 have the same horizontal position (in a straight line). ) (see Figure 5). As shown in FIG. 2, the front ceiling wall 24 is higher than the intermediate ceiling wall 28, the front bottom wall 27 is lower than the intermediate bottom wall 31, and the vertical width of the inlet side end 21 is It is clearly set longer (larger) than the vertical width of the end 23 opposite to the entrance side.

As shown in FIG. 5 , the front left side wall 25 is closer to the left side (cylinder head 2 side) than the rear left side wall 33 , and the lateral width of the end 23 opposite to the inlet side is greater than the lateral width of the intermediate portion 22 . is large, and the lateral width of the entrance-side end 21 is set to be larger than the lateral width of the anti-entrance-side end 23 . The angle α preferably satisfies 40 degrees≦α≦70 degrees (eg, 55 degrees), and the angle β preferably satisfies 10 degrees≦β30 degrees (eg, 19 degrees), but is not limited thereto.

Specifically, the left side wall (the side wall on the side of the cylinder head 2) 8W of the intake body 8H is a recessed wall in which the middle portion in the longitudinal direction (the front-rear direction) is closer to the right side (the side opposite to the cylinder head 2) than both end portions. (see FIG. 6). At the boundary portion between the entrance-side end portion 21 and the intermediate portion 22, the rear portion 24a of the front ceiling wall 24 and the rear portion 27a of the front bottom wall 27 are arranged such that the vertical width decreases from the entrance-side end portion 21 toward the intermediate portion 22. is formed, and the ceiling wall 8T and the bottom wall 8U of the intake main body 8H are inclined (see FIG. 2). A right side wall (a side wall on the side opposite to the cylinder head 2) 8Q of the intake main body 8H is formed as a straight wall with a constant lateral position (see FIG. 5).

As a result, the intake main body 8H has a cross-sectional area (volume) of the inlet-side end 21 > a cross-sectional area (volume) of the counter-entrance-side end 23 > a cross-sectional area (volume) of the intermediate portion 22 . is set to a narrowed shape (see FIGS. 2 and 5). The "cross-sectional area" referred to here is the cross-sectional area when cut by a plane extending vertically and horizontally. The cross-sectional shape of the intake main body 8H is basically a vertically elongated rectangle, and particularly the inlet-side end portion 21 and the intermediate portion 22 tend to be vertically elongated.

As shown in FIGS. 1 to 6, four branch pipes 8A to 8D are arranged in the front-rear direction. and/or from the bottom wall 8U (see FIG. 3). Mounting flanges 36 for integrating the first to fourth branch pipes 8A to 8D are formed at the distal ends of the first to fourth branch pipes 8A to 8D. The mounting flange 36 attached to the cylinder head 2 has first to fourth openings 41 to 44 corresponding to the first to fourth passages 8a to 8d, which are internal flow paths of the first to fourth branch pipes 8A to 8D, respectively. is formed (see FIG. 1).

The position of the front end (front surface 8f) of the intake main body 8H in the front-rear direction is different from that shown in FIGS. As can be seen from 8, it is set to correspond to the front-rear central portion between the first intake port pa and the second intake port pb. The rear end (rear wall 8R) of the intake body 8H is positioned rearward of the fourth intake port pd. The "openings 41 to 44 side" of the intake main body 8H can be rephrased as "the mounting flange 36 arrangement (existence) side", "extending direction of the branch pipes 8A to 8D", or "cylinder head 2 side".

As a result, as shown in FIGS. 3 and 5, except for the fourth branch pipe 8D, the first to third branch pipes 8A to 8C are inclined forward in the vertical direction as they go leftward. It is considered to be a slanted tube. The second to fourth branch pipes 8B to 8D are drawn forward and downward mainly from the bottom wall 8U of the intake main body 8H, and the first branch pipe 8A is drawn forward and downward while straddling the bottom wall 8U and the front wall 8F. (See Figure 2).

As shown in FIGS. 7 and 8, the left side wall 8W of the intake main body 8H is provided with a return port 19 to which the blow-by gas passage 14 is connected. Specifically, as shown in FIGS. 1, 5, and 6, the front part of the intermediate left side wall 29 of the intermediate part 22 is formed with a vertically long reinforcing part 8s that protrudes slightly to the left. A pipe 19a is supported through its upper portion. The pipe 19A is taken out in the left lateral direction perpendicularly to the front-rear direction in a posture that slightly rises (up left) from the horizontal. A blow-by gas passage 14 is fitted in the pipe 19a (see FIGS. 7 and 8), and the head cover 3 and the intake main body 8H are communicated with each other so that the blow-by gas can be returned to the intake passage.

Here, the characteristics of the shape of the intake manifold 8 are summarized as follows. As shown in FIGS. 1 to 6, on the side wall (front wall) 8F on the upper side (front side) in the bias direction (rear) with respect to the first to fourth openings 41 to 44 (or the mounting flange 36) of the intake main body 8H. An intake inlet i is provided. The cross-sectional area of the inlet-side end 21 on the side where the intake inlet i is located in the longitudinal direction (front-rear direction) of the intake main body 8H is the intermediate portion 22 and the counter-entrance-side end 23 (other than the inlet-side end 21 of the intake main body 8H). The intake main body 8H is set to have a base bulging shape (front bulging shape) so as to be larger than the cross-sectional area of the portions 22, 23). Base bulge can also be translated into base widening, base narrowing, and the like.

In addition, the intermediate portion 22 and the non-entrance side end portion 23 (of the intake main body 8H) are arranged such that the cross-sectional area of the non-entrance side end portion 23, which is the rear end portion of the intake main body 8H, is larger than the cross-sectional area of the intermediate portion 22. Portions 22, 23 other than the inlet side end 21) are set in a forward (rear) bulging shape (mainly bulging leftward) (see FIG. 5). Swelling at the front can be rephrased as broadening at the front, narrowing at the base, and the like.

The extraction point of the first branch pipe 8A (the proximal end of the first proximal pipe portion 40) at the inlet-side end portion 21 and the intake inlet i are located on opposite sides in the lateral direction (horizontal direction). That is, the extraction location of the first branch pipe 8A is set on the right side of the front wall 8F, and the intake inlet i is set on the left side of the front wall 8F (see FIG. 4A). The first branch pipe 8A is taken out from the inlet side end portion 21 with an inclination angle toward the upper side (front side) in the deviation direction (front-rear direction) and the lower left (see FIGS. 1 to 3).

As shown in FIG. 3, the extraction angles θ1 to θ4 of the first to fourth branch pipes 8A to 8D from the intake main body 8H (inclination angles with respect to the front-rear direction when viewed in the up-down direction) vary from the fourth extraction angle θ4 to the first angle. It is set to decrease toward the take-out angle θ1, and the first take-out angle θ1 is a prominently small value. For example, the first take-out angle θ1 is around 15 degrees (0 degrees≦θ1<30 degrees), the second take-out angle θ2 is around 55 degrees (45 degrees≦θ2≦65 degrees), and the third take-out angle θ3 is around 77 degrees ( 70 degrees≦θ2≦80 degrees), and the fourth extraction angle θ2 is around 90 degrees (80 degrees≦θ2≦100 degrees).

Each of the branch pipes 8A to 8D is taken out from the bottom wall 8U of the intake main body 8H and/or the side walls 8W and 8Q near the bottom wall 8U, and the shape of the inlet side end portion 21 when viewed in the opening arrangement direction is set to be vertically long. , the intake inlet i is provided in the upper part of the front wall (side wall on the right side in the bias direction) 8F (see FIGS. 3 and 4A). The vertical width of the intermediate portion 22 is set to be smaller than the vertical width of the inlet-side end portion 21 , and at the boundary portion between the inlet-side end portion 21 and the intermediate portion 22 , the width increases from the inlet-side end portion 21 toward the intermediate portion 22 . The ceiling wall 8T is sloped rearwardly (rear portion 24a) and the bottom wall 8U is sloped rearwardly upward (rear portion 27a) so that the vertical width is reduced (see FIG. 2).

As shown in FIGS. 1, 5, and 6, the left side of the front end of the intermediate portion 22 (the end of the inlet-side end 21 side of the portions 22 and 23 other than the inlet-side end 21 of the intake body 8H) A blow-by gas return port 19 is provided at a portion of the wall (side wall on the side of the openings 41 to 44) 8W, which is very close to the inclined side wall 8k. The slanted side wall 8k is a slanted wall that inclines toward the opening side (on the mounting flange 36 side and to the left) as it approaches (forwards) the inlet side end portion 21 in the opening arrangement direction (front-rear direction).

By the way, on the ceiling wall 8T of the intake main body 8H, there is a mounting seat 39 (Figs. 1, 2, 8) for mounting a measurement device 38 (see Figs. 6) are provided. The right side wall 8Q of the intake main body 8H is provided with three front and rear lateral bosses 45 (see FIGS. 2, 3 and 5) projecting sideways, and the ceiling wall 8T has three front and rear upper bosses projecting upward. A portion 46 (see FIGS. 1, 2 and 6) is provided. The horizontal boss 45 is used, for example, when fixing various parts such as a guide (not shown) for an oil gauge 47 (see FIGS. 7 and 8) or a fuse box 18 (or its supporting member) instead of the mounting portion 20. can be used for Similarly, the upper boss portion 46 also enables mounting of various parts.

[About actions and effects]
As described above, in the intake manifold having a branched pipe structure in which the intake main body 8H is arranged biased in the opening arrangement direction with respect to the openings 41 to 44, the first end on the upper (front) side in the direction of bias (front-rear direction) In order to allow intake air to flow through the branch pipe 8A, it is necessary to turn about 180 degrees immediately after entering the intake main body 8H from the intake inlet i, which tends to be the most difficult to flow among the plurality of branch pipes (poor suction efficiency). There is

Therefore, according to the present invention, the cross-sectional area of the inlet-side end 21 on the side of the intake inlet i in the longitudinal direction of the intake main body 8H is the intermediate portion 23 and the counter-entrance-side end 23 (portion 22 other than the inlet-side end 21, 23). In this case, the inlet side end portion 21 may be longer than the intermediate portion 22 both upwardly and downwardly, and the intake main body 8H may have a vertically elongated shape with a longer left-right width.

In other words, due to the shape change portion where the cross-sectional area is reduced from the inlet side end portion 21 to the intermediate portion 22, in the internal space of the inlet side end portion 21, the intake air that enters from the intake inlet i in a biased direction (front-rear direction). It is possible to change the direction of the flow of the fluid to a large extent without difficulty, and it is possible to smoothly flow the fluid into the first branch pipe 8A (see FIG. 3, details will be described later). In addition, in the other branch pipes 8B, 8C, and 8D, the direction of flow of the intake air entering from the intake port i in a biased direction (front-to-rear direction) is sufficiently spaced from the intake port i. target inspiration flows smoothly.

Therefore, the intake air from the intake inlet i can flow smoothly and efficiently into the first branch pipe 8A, which is located on the uppermost side in the biased direction and in which the intake air is particularly difficult to flow. The easiness of flow to a plurality of branch pipes can be made equal to each other as much as possible while making the 8H compact without unnecessarily enlarging it.

As a result, the intake manifold 8 adopts a distorted shape in which the intake main body 8H is arranged biased in the cylinder arrangement direction with respect to the branch pipes 8A to 8D mainly by further structurally devising the intake main body 8H. It can be further improved so that the intake air flows through the branch pipes 8A to 8D as evenly as possible while achieving the above.

The intake main body 8H of the intake manifold 8 has a left wall 8W on the left side (cylinder head side) and an intermediate portion (intermediate portion 22) in the longitudinal direction of the intake main body 8H. ) on the right side (anti-cylinder head side) (see FIGS. 5 and 6). An intermediate left side wall 29 is recessed rightward from the front left side wall 25 and the rear left side wall 33 .

Therefore, a sufficient space is secured between the intermediate portion 22 and the cylinder head 2 on the left and right sides, and a wire harness (not shown) routed in the front and rear at the upper right corner portion of the cylinder head 2 is installed. The configuration facilitates assembly work and maintenance work using hands and fingers, such as assembly of the mounting flange 36 to the cylinder head 2 or maintenance and inspection of various types of piping.

The intake main body 8H has a vertically elongated rectangular cross section that is short in the left and right direction and long in the vertical direction, and has a sufficient internal volume. Therefore, the intake main body 8H is provided so that the lateral position of the right side wall 8Q is closer to the cylinder head 2 than in the conventional product. The passage lengths of the branch pipes 8A to 8D are also sufficiently long.
As a result, it is possible to make the upper part of the engine more compact by suppressing the sideways protrusion of the engine, while not impairing the ease of maintenance work around the cylinder head. A new intake manifold 8 is realized.

In the intake manifold 8, an intake inlet i is provided at the upper end of the front wall 8F at a leftward position (see FIG. 4A), and an inclined sidewall 8k having a relatively large angle The internal space of the main body is constructed in such a state that it extends from the inlet-side end portion 21 to the intermediate portion 22 and largely leans to the left (see FIG. 5). Therefore, the air-fuel mixture (or air) entering from the intake port i is in a state of flowing while turning sharply to the right as indicated by the four solid line arrows y shown in FIG. is likely to be in a negative pressure state, and the effect of promoting the return movement of the blow-by gas to the intake main body 8H is obtained.

In addition, the inclined ceiling wall 24a (the rear part 24a of the front ceiling wall 24) and the inclined ceiling wall 27a (the rear part 27a of the front bottom wall 27) provided above and below the rear part of the inlet side end 21 form a dashed arrow in FIG. As indicated by h, the air-fuel mixture (or air) entering the intake main body 8H from the intake port i is likely to turn downward and move in a swirling motion.
Among the plurality of branch pipes 8A to 8D, the first branch pipe 8A positioned closest to the side wall (front wall) 8F at one end in the cylinder arrangement direction is the other longitudinal end of the intake main body 8H in the cylinder arrangement direction. It has a first base end tube portion 40 taken out from the intake main body 8H in a composite inclined posture facing both the side wall (rear wall) 8R and the upward direction (see FIG. 3).

Therefore, compared to the conventional intake manifold, the air-fuel mixture from the intake main body 8H flows into the first passage 8a of the first branch pipe 8A, which is in the opposite direction to the intake inlet i and is originally in the most difficult situation. (or air) is easier to flow in, and there is an advantage that the intake efficiency at the first intake port pa is improved (see FIG. 2). In this case, there is an advantage that the suction efficiency can be further improved by the structure in which the intake inlet i is shifted to the left and the proximal end of the first branch pipe 8A is shifted to the right (see FIG. 5).

[Another embodiment]
The number of branch pipes 8A-8D may be more than four. The ratio of the lengths of the inlet side end portion 21, the intermediate portion 22, and the counter-entrance side end portion 23 in the cylinder arrangement direction (the ratio of the front-to-rear length of the recessed portion to the overall length of the left side wall 8W) is shown in FIGS. It is possible to arbitrarily set a ratio other than the ratio illustrated in .

The intake main body 8H and the intake manifold 8 shown in (1) to (3) below may also be used.
(1) The intake main body 8H has the cross-sectional area of the non-inlet side end 23 that is the same as the cross-sectional area of the intermediate portion 2, that is, the portions 22 and 23 other than the inlet side end 21 of the intake main body 8H are first (rear). The intake main body 8H is not in a bulging shape.
(2) The intake main body 8H has a bulging base shape due to the intermediate right side wall 30 being closer to the opening side (left side) than the front right side wall 26 .
(3) An intake manifold in which the right side wall 8Q of the intake main body 8H on the side opposite to the opening side is formed into a concave wall in which the middle portion in the longitudinal direction is closer to the opening side than both end portions.

8A to 8D branch pipes (1st to 4th branch pipes)
8F Side wall (front wall) on the upper side in the bias direction
8H Intake body 8Q Side wall near bottom wall (right side wall)
8T Ceiling wall 8U Bottom wall 8W Side wall near bottom wall (left side wall), side wall on opening side 8k Inclined wall 19 Return port (blow-by gas)
21 inlet-side end 22 portion other than inlet-side end (intermediate portion)
23 Portion other than entrance side end (opposite entrance side end)
41 to 44 openings (1st to 4th openings)
i Intake inlet pa~pd Intake port

Claims (11)

comprising a plurality of branch pipes having openings corresponding to respective intake ports, and one intake main body communicating with the proximal end sides of the plurality of branch pipes,
The shape of the intake main body is a box shape elongated in the opening arrangement direction in which the plurality of openings are arranged, and the position of the intake main body in the opening arrangement direction is biased with respect to the plurality of openings,
an air intake inlet is provided in a side wall on the upper side in a bias direction with respect to the opening of the air intake main body;
The air intake main body is arranged such that the cross-sectional area of the inlet side end on the side where the air intake inlet is located in the longitudinal direction of the air intake main body is larger than the cross-sectional area of the portion of the air intake main body other than the inlet side end. An intake manifold that is set in a base bulge shape. 2. The intake manifold according to claim 1, wherein a first branch pipe, of the plurality of branch pipes, located on the most upstream side in the bias direction is led out from the inlet side end portion. 3. The intake manifold according to claim 2, wherein the extraction location of the first branch pipe at the inlet side end and the intake inlet are set so as to be laterally opposite to each other. 4. The intake manifold according to claim 2 or 3, wherein the first branch pipe is taken out from the inlet side end portion with an inclination angle toward the upper side in the bias direction. The plurality of branch pipes are taken out from the bottom wall of the intake main body and/or a side wall near the bottom wall, and the shape of the inlet side end portion when viewed in the opening arrangement direction is set to be vertically long. 5. The intake manifold according to any one of Clauses 4. 6. An intake manifold according to claim 5, wherein said intake inlet is provided in an upper portion of said upper side wall. A vertical width of an intermediate portion adjacent to the inlet-side end of the intake main body other than the inlet-side end is set smaller than a vertical width of the inlet-side end,
At the boundary between the inlet side end and the intermediate section, the ceiling wall and/or the bottom wall of the intake main body are sloped so that the vertical width decreases from the inlet side end toward the intermediate section. The intake manifold according to any one of claims 1 to 6, wherein the intake manifold is The cross-sectional area of the non-entrance side end of the lower side end in the bias direction of the portion other than the inlet side end of the intake main body is intermediate between the inlet side end and the non-entrance side end. 8. The intake manifold according to any one of claims 1 to 7, wherein a portion of the intake main body other than the inlet side end portion is set to have a bulging shape so as to be larger than the cross-sectional area of the portion. 9. The air intake main body according to any one of claims 1 to 8, wherein a blow-by gas return port is provided at an end portion of the intake main body other than the inlet side end portion on the side of the inlet side end portion. intake manifold. 10. The intake manifold according to claim 9, wherein the return port is provided in the vicinity of an inclined wall formed at a boundary portion between the inlet-side end portion and the intermediate portion of the intake main body. The inclined wall is formed such that a side wall of the intake main body on the side of the opening on which the opening is provided is inclined so as to come closer to the opening side as it approaches the inlet side end portion in the opening arrangement direction. 11. The intake manifold according to Item 10.

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