JPH059490Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial field of application) This invention relates to an engine intake system, and more specifically, to an improvement in the connection structure of a U-shaped connecting pipe for supplying the intake air in a surge tank located above the cylinder head to the intake port of the cylinder head or to an intake pipe connected to the intake port.

(Prior Art) Conventionally, in the intake system of an engine, the intake air vibrates at a natural frequency determined by the shape and length of the intake passage, causing pressure fluctuations.
The so-called inertia supercharging engine intake system is well known, which actively utilizes this phenomenon and uses its dynamic effect to efficiently push intake air into the cylinders to increase intake air filling efficiency. .

In such an inertia supercharging type intake system, in order to utilize the dynamic effect of intake air in the low speed range where the engine is frequently used, it is necessary to increase the length of the intake pipe. Conventionally, as a solution to increasing the length of the intake pipe, a U-shaped structure has been proposed between the surge tank placed above the cylinder head of the engine and the intake pipe connected to the intake port opening into the cylinder head. A curved extension pipe is interposed to extend the length of the intake pipe on the downstream side of the surge tank. For example, in the specification and drawings of the previously filed Japanese Patent Application No. 59-65624, the present applicant discloses a case where the above extension tube is applied to a V-type engine.

(Problem to be solved by the invention) By the way, when connecting the upstream and downstream ends of the extension pipe to the surge tank and the intake pipe on the cylinder head side, as is usually done,
Although a mounting flange may be formed at each end of the extension pipe and the bolts may be fastened using the mounting flange, this increases the bolt fastening work and makes it difficult to assemble the extension pipe. be. Furthermore, if there is a misalignment between the connecting parts due to manufacturing errors in each part, stress is applied to the extension pipe by bolting, which may cause deformation, damage, or a decrease in sealing performance at the joint. . especially,
If the structure is such that the extension pipe is attached after the surge tank is integrally assembled to the intake pipe, and the joints of the extension pipe in the surge tank and intake pipe open in the same direction, proceed first. Due to errors in assembling the surge tank to the intake pipe, errors in connection may occur on both the surge tank side and the intake pipe side of the extension pipe, making the above problem significant.

Therefore, in order to avoid the above problems, one end of the extension pipe is bolted through a so-called stupid hole that is larger than the diameter of the bolt, and the other end is fitted through a sealing material. It is conceivable to leave positional deviations due to manufacturing errors and assembly errors as they are to eliminate stress during assembly.

However, extension pipes are usually formed so that the inner diameter, or passage area, gradually decreases from the upstream end to the downstream end, with the aim of smoothing inflow of intake air into the surge tank and increasing its flow velocity. Therefore, depending on the selection of the end on the side where the bolts are fastened, the connection may occur due to a positional misalignment between the opening of the extension pipe and the opening on the other side due to the manufacturing error or assembly error. There is a risk that the passage area in the area may be reduced.

This invention was made in view of these points,
The purpose of this is to connect each end of the connecting pipe, which is curved in a U-shape to connect the surge tank and the intake port or intake pipe of the cylinder head, to the other end, such as the extension pipe mentioned above. By appropriately selecting the end on the side where the bolt is to be fastened, the connecting pipe can be easily assembled, and the passage area at the joint can be minimized due to manufacturing errors and assembly. The purpose is to reliably prevent the size from becoming smaller due to positional deviation due to errors.

(Means for Solving the Problems) In order to achieve the above object, the present invention, as described above, includes a surge tank disposed above the cylinder head, and an intake port formed in the cylinder head. In an engine intake system, the surge tank is integrally connected and fixed to the cylinder head or the intake pipe, and the upstream end of the connection pipe is connected to the surge tank. The opening in the surge tank wall and the intake port or intake pipe to which the downstream end of the connecting pipe is connected open in substantially the same direction.

The connecting pipe is U-shaped, and the upstream end of the connecting pipe is fastened to the wall around the opening of the surge tank with a bolt that is inserted through a bolt insertion hole of a mounting flange formed at the upstream end of the connecting pipe. The downstream end of the connecting pipe is configured to be fitted and connected to the intake port or the intake pipe via a sealing material.

The bolt insertion hole of the mounting flange is a hollow hole having a larger diameter than the bolt, and the opening area of one of the opening in the surge tank wall and the opening at the upstream end of the connecting pipe is made larger than the other.

(Function) With the above configuration, in the present invention, the surge tank is integrally attached to the cylinder head or intake pipe of the engine in advance, and then the opening of the surge tank is opened in substantially the same direction. A U-shaped connecting pipe is attached to the intake port or the intake pipe to connect the two. When assembling this connecting pipe, first, its downstream end is fitted to the intake port or intake pipe via a sealing material, and then the mounting flange at the upstream end is attached to the wall around the opening of the surge tank. It is fastened with a bolt that passes through the bolt insertion hole. The above bolt insertion hole is
Since the hole is larger in diameter than the bolt, even if there is a manufacturing error such as the dimensions of the U-shaped connecting pipe or an error in the assembly of the surge tank, the error will be avoided when the upstream end is attached to the wall of the surge tank with the bolt. This can be absorbed by adjusting the position of the bolt by the relative displacement of the bolt in the bolt insertion hole when tightening. Moreover, since the downstream end of the connecting pipe is fitted to the upstream end of the intake port or intake pipe via a sealing material, the downstream end of the connecting pipe is relative to the upstream end of the intake port or intake pipe in the direction of its center line. By moving it, it is possible to absorb errors in the bolt tightening direction. These make it possible to absorb any errors in the three-dimensional direction of the connecting pipe,
Connecting pipes can be easily assembled without leaving any stress during assembly.

In addition, in order to absorb the manufacturing errors and assembly errors mentioned above, the centers of the upstream end opening of the connecting pipe and the opening in the surge tank wall are misaligned, but the connecting pipe is oriented downstream from the upstream end. In the past, the passage area was gradually decreasing, and one of the openings at the upstream end and the opening in the surge tank wall was larger than the other, so even if there was a positional shift like the one described above, the passage area at the connection part would still be small. A size determined by the smaller side of the opening on the surge tank side or the opening at the upstream end of the connecting pipe can be ensured, and it is therefore possible to prevent the passage area from becoming small at the connecting part.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

In the drawings, 1 is a six-cylinder V-type engine, and the engine 1 has left and right cylinder forming parts 2a, 2a inclined at a predetermined angle, and three cylinders 3 are formed in each cylinder forming part 2a. V
It comprises a letter-shaped cylinder block 2 and two cylinder heads 4, 4 joined to the upper surfaces of left and right cylinder forming parts 2a, 2a of the cylinder block 2, respectively. A piston 5 is reciprocably fitted into each cylinder 3 of the cylinder block 2, and a cylinder 6 is constituted by air surrounded by the inner wall surface of the cylinder 3 and the lower surface of the cylinder head 4.
A combustion chamber 7 defined by a piston 5 is formed therein. Incidentally, among the six cylinders 6, 6, . . . , the three cylinders 6, 6, . . . on the left side and the three cylinders 6, 6, .

Also, reference numeral 8 denotes an intake passage for supplying intake air to the combustion chamber 7 in each cylinder 6.
The downstream end of each intake port 9 is constituted by an intake port 9 formed in each cylinder head 4. The downstream end of each intake port 9 opens via an intake valve 10 into the underside of the cylinder head 4 facing the combustion chamber 7, while the upstream end opens into the side surface facing the opposing cylinder head 4 (the side surface facing the left-right center of the engine 1), and the downstream end of an intake pipe 11 connected to the upstream end of the intake port 9 and forming part of the intake passage 8 is flange-connected to the side surface of the cylinder head 4. The upstream end of the intake pipe 11 extends upward toward the opposing cylinder head 4, and is formed with a fitting flange portion 11a having a larger diameter than the other portions.

On the other hand, a surge tank 12 forming an enlarged portion of the intake passage 8 is disposed above between the left and right cylinder heads 4, 4, and the surge tank 12 extends in the longitudinal direction of the engine 1, that is, in the crankshaft direction. The interior thereof is partitioned into two left and right chambers 14, 14 by a partition wall 13 extending in the front-rear direction, and the partition wall 13 is provided with an on-off valve (not shown) for communicating or blocking communication between the two chambers 14, 14. ing. Also,
A bolt insertion hole 13a passing through the partition wall 13 in the vertical direction is formed in a part of the partition wall 13, and the bolt 15 inserted into the bolt insertion hole 13a is inserted into each intake pipe 11.
The surge tank 12 is integrally fixed and supported on each intake pipe 11 (engine 1) by being screwed into a screw hole 11c of a bolt boss 11b protruding from the upper surface of the pipe wall.

There are three openings 12a, 12a, ... (connection parts) on the left and right side walls of the surge tank 12, respectively.
are formed, and each opening 12a is
It opens in substantially the same direction (left or right horizontal direction) as the upstream end of each predetermined intake pipe 11 corresponding to a. Each opening 12 of this surge tank 12
a and the upstream end of each intake pipe 11 corresponding to each opening 12a are connected by an extension pipe 16 as a connecting pipe curved in a U-shape for extending the length of the intake passage 8. and engine 1
Control the opening and closing of the on-off valve according to the operating status of the
The confluence point of the intake passages 8 connected to the plurality of cylinders 6, 6 whose opening timings overlap the intake valve 10 is changed, and the confluence point is connected to the surge tank 12 when the on-off valve is closed.
On the upstream side, when the on-off valve is opened, the confluence point is switched to the inside of the surge tank 12, thereby inertial supercharging of the intake air over a wide operating range of the engine 1 by dynamic effect.

Each of the extension pipes 16 is formed such that the inner diameter, that is, the passage area gradually decreases from the upstream end toward the downstream side, and the upstream end opening 16a is connected to a surge tank corresponding to the opening 16a. 12, and the downstream end opening 16a is set to have approximately the same diameter as the upstream end opening 11d of the corresponding intake pipe 11. Further, a mounting flange portion 16c is formed at the upstream end of each extension pipe 16, and a plurality of bolt insertion holes (not shown) are formed through the mounting flange portion 16c. The upstream end of the extension pipe 16 is connected to the surge tank 1 by the penetrating fastening bolts 17, 17, .
It is fastened to the side wall around the opening 12a of No. 2.
Each of the bolt insertion holes described above is a so-called stupid hole that is larger than the outer diameter of the bolt 17. On the other hand, the downstream end of the extension pipe 16 is fitted and connected to the fitting flange portion 11a at the corresponding upstream end of the intake pipe 11 via a sealing material 18 fitted to the outer circumference of the pipe wall.

In the figure, reference numeral 19 denotes an injector that injects fuel from the downstream end portion of each intake pipe 11 into each intake port 9 of the cylinder head 4.

Therefore, in the above embodiment, the intake pipe 11 attached to the side surface of each cylinder head 4 of the engine 1 and the surge tank 12, which is integrally fixed and supported to the intake pipe 11 with bolts 15 in advance, are arranged as an extension. When connecting via the pipe 16, first, the downstream end of the extension pipe 16 is fitted to the fitting flange portion 11a at the upstream end of the intake pipe 11 via the sealing material 18, and then the next connects the upstream end opening 16a of the extension pipe 16 to the opening 12a in the side wall of the surge tank 12.
The extension pipe 16 can be assembled by inserting the fastening bolts 17, 17 through the bolt insertion holes of the flange 16c and fastening the mounting flange portion 16c at the upstream end accordingly.

At that time, only the upstream end of the extension pipe 16 is bolted, and the downstream end is fitted and connected to the intake pipe 11, so the work such as bolt tightening is halved compared to the case where the upstream and downstream ends are fastened with bolts. Therefore, the extension pipe 16 can be easily assembled.

Also, due to manufacturing errors in the intake pipe 11, surge tank 12, extension pipe 16, etc., and assembly errors of the surge tank 12 to the intake pipe 11, the downstream end may be different from the fitting flange portion 11a at the upstream end of the intake pipe 11.
Even if a slight positional deviation occurs between the upstream end position of the extension pipe 16 fitted to the opening 12a of the surge tank 12, the bolts cannot be inserted through the mounting flange 16c of the extension pipe 16. Since the hole is a so-called stupid hole having a larger diameter than the fastening bolt 17, the bolt can be fastened while leaving the above-mentioned positional deviation as it is.
Moreover, the downstream end of the extension pipe 16 is fitted and connected to the fitting flange portion 11a at the upstream end of the intake pipe 11 via the sealing material 18, so that the fitting flange portion 11a at the downstream end of the extension pipe 16 is Fastening bolt 17 due to relative movement in the center line direction
Errors in the tightening direction can also be absorbed. Therefore, any errors in the three-dimensional direction of the extension tube 16 can be absorbed, and the extension tube 1
It is possible to assemble the extension pipe 16 without applying stress to the extension pipe 16, thereby preventing deformation and breakage of the extension pipe 16, and preventing deterioration of sealing performance at the connection portion.

Furthermore, due to the above-mentioned positional deviation, the center of the upstream end opening 16a of the extension pipe 16 does not correspond to the center of the opening 12a of the surge tank 12, but the extension pipe 16 is moved downstream from the upstream end. The inner diameter gradually decreases, and the upstream end opening 16a is larger than the opening 12a of the surge tank 12, so even if there is the above-mentioned positional deviation, the passage area at the connection between the surge tank 12 and the extension pipe 16 remains the same as that of the surge tank. 12 openings 12a
Therefore, it is possible to reliably prevent the passage area at the connecting portion from becoming smaller due to manufacturing errors or assembly errors.

In the above embodiment, the extension tube 16
The upstream end opening 16a of the extension pipe 16 is made larger than the opening 12a of the surge tank 12, but conversely, the opening 12a of the surge tank 12 may be made larger than the upstream end opening 16a of the extension pipe 16. , it is possible to achieve the same effects as in the above embodiment.

Furthermore, in the above embodiment, the extension tube 1
The present invention was applied to the intake system of a V-type engine equipped with 6, but the present invention has a surge tank that is integrally connected and fixed to the cylinder head above the cylinder head, and the surge tank is connected to the cylinder head by a connecting pipe. It can also be applied to an engine intake system which is connected directly to the intake port of the cylinder head.

(Effects of the invention) As described above, according to the invention, there is provided a surge tank disposed above the cylinder head of the engine so as to be integrally connected to the cylinder head or the intake pipe, and an intake port in the cylinder head or the intake port. When connecting joints that open in the same direction as the intake pipes to be connected using a U-shaped connecting pipe, insert the mounting flange at the upstream end into the surge tank wall through a hole with a diameter larger than the bolt. While bolts are fastened through bolt insertion holes, the downstream end is fitted and connected to the intake port or intake pipe via a sealing material, and the opening area of one of the opening in the surge tank wall and the opening at the upstream end of the connecting pipe is By making the connecting tube larger than the other, it is possible to easily assemble the connecting pipe and to prevent the passage area at the connecting portion from becoming smaller due to manufacturing errors and assembly errors.

[Brief explanation of the drawing]

The drawing is a sectional view of a main part showing an embodiment of the present invention. 1...Engine, 4...Cylinder head, 9...
... Intake port, 11 ... Intake pipe, 12 ... Surge tank, 12a ... Opening, 16 ... Extension pipe, 17 ... Fastening bolt, 18 ... Sealing material.

Claims (1)

[Scope of Claim for Utility Model Registration] The intake air of an engine is constructed by connecting a surge tank disposed above the cylinder head and an intake port formed in the cylinder head or an intake pipe connected to the intake port through a connecting pipe. In the device, the surge tank is integrally connected and fixed to the cylinder head or intake pipe, and the opening in the wall of the surge tank to which the upstream end of the connecting pipe is connected is connected to the downstream end of the connecting pipe. It opens in substantially the same direction as the intake port or intake pipe, and the connecting pipe has a U-shape, and the upstream end of the connecting pipe is connected to the wall around the opening of the surge tank, and the upstream end of the connecting pipe is connected to the wall around the opening of the surge tank. They are fastened by bolts that pass through the bolt insertion holes of the formed mounting flange, while the downstream end of the connecting pipe is fitted and connected to the intake port or intake pipe via a sealing material, and the bolt insertion holes of the mounting flange are connected with bolts. An intake system for an engine, characterized in that the opening area of one of the opening in the wall of the surge tank and the opening at the upstream end of the connecting pipe is larger than the other.