JPH0141904Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an intake system for a multi-cylinder engine.

[Prior art]

Recently, in vehicle engines, especially multi-cylinder engines, from the viewpoint of suppressing engine vibration, V-type engines have been developed in which cylinders are tilted at a predetermined angle and faced to each other, as shown in Japanese Patent Application Laid-open No. 56-113042, for example. The structure is attracting attention. In particular, in this V-type engine, due to its structure, there is a relatively large space between the opposing cylinders, so a surge tank, which is an enlarged part of the intake passage, is placed above the cylinders. There is.

Furthermore, in recent engines, the intake pipe that connects the surge tank and the engine tends to be long in order to obtain a so-called inertia supercharging effect that improves charging efficiency by utilizing intake inertia.

However, as mentioned above, in a V-type engine with a surge tank located above between the cylinders, if an attempt is made to make the intake pipe long, the gap between the cylinder and the surge tank will increase and the overall height of the engine will increase. On the other hand, when trying to lower the overall height of the engine, the gap between the cylinder and the surge tank became smaller, making it impossible to form a long intake pipe.

In response, the present applicant has developed an intake system for a multi-cylinder engine such as a V-type engine that eliminates all of the above-mentioned problems. That is, the upstream end of the intake pipe that connects the engine and the surge tank is opened in the side wall of the surge tank, and the intake pipe is curved in a U-shape in the downstream direction from the upstream end and inclined in the direction of the output shaft of the engine. form a U-shaped part,
In addition, after extending the intake pipe on the downstream side of the U-shaped part into the downward projected plane of the surge tank, its most downstream end is connected to the engine. The tube is formed into a long length.

[Purpose of invention]

This invention aims to provide an intake system for a multi-cylinder engine that can further reduce the overall height of the engine under such circumstances.

[Structure of the idea]

In the above-mentioned intake system for a multi-cylinder engine, one possible method for reducing the overall height of the engine is to form the cross-sectional shape of the intake pipe into a substantially horizontally flattened shape. However, in the intake system of the multi-cylinder engine described above, since the intake pipe is curved in a U-shape and inclined in the direction of the output axis of the engine as described above, the cross-sectional shape of the intake pipe is simply flattened in a substantially horizontal direction. If the cross section of the intake pipe is formed into a perfect circle, there will be a large difference in the distance that the intake air flows between the outer part and the inner part of the U-shaped part of the intake pipe. A difference occurs in the flow velocity, and frictional heat is generated due to the viscous resistance of the intake air, which causes an increase in the intake resistance.

Therefore, this idea was developed in a multi-cylinder engine.
A surge tank is arranged above the cylinder so that its long axis coincides with the output shaft direction of the engine, and a plurality of intake pipes extending from the side of the surge tank are connected to each other.
The intake pipe is curved in the shape of a letter and inclined in the direction of the output axis of the engine, and its tip side extends into the downward projection plane of the surge tank, and its tip end is connected to the engine body, and the intake pipe has a cross-sectional shape. is flattened in a substantially horizontal direction at the upstream end of the side wall of the surge tank, gradually becomes approximately circular from the upstream end to the center of the U-shaped portion, and gradually again from the center of the U-shaped portion to the downward projection surface of the surge tank. It is formed to have a flat shape in a substantially horizontal direction, thereby further reducing the overall height of the engine and suppressing an increase in intake resistance at the U-shaped portion.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 to 3 show an intake system for a V-type engine according to an embodiment of the present invention. In the figure, 1
is an engine body, and the engine body 1 has six cylinders, first to sixth cylinders, and the first to sixth cylinders are the first, second, and third cylinder groups 2a whose ignition order is not consecutive. 4th, 5th, and 6th cylinder groups 2b, and the two cylinder groups 2a, 2
b are arranged at a predetermined angle and facing each other, that is, in a V-shape (see dashed lines a and b in FIG. 1). Here, in engine body 1, the crank angle is
It is assumed that the first, fourth, second, sixth, third, and fifth cylinders are fired in this order every 120 degrees.

Further, a surge tank 3 forming an enlarged portion of the intake passage is arranged above the cylinder groups 2a and 2b, and a throttle chamber 15 is connected to the upstream end of the surge tank 3. The top surface of the surge tank 3 is sloped so that it becomes lower toward the front of the vehicle body, and the interior of the surge tank 3 is divided into two by a partition wall 4. The upstream ends of intake pipes 5a and 5b connecting the surge tank 3 and the engine main body 1 are opened in the left and right side walls of the surge tank 3, respectively. The intake pipes 5a, 5b are composed of U-shaped portions 6a, 6b that are curved in a U-shape in the downstream direction from the upstream end, and intersection portions 7a, 7b connected to the downstream side of the U-shaped portions 6a, 6b. The U-shaped portions 6a and 6b are inclined in the direction of the output shaft of the engine. Further, the intersection portions 7a, 7b extend within the downward projected plane of the surge tank 3, and each intersection portion 7a, 7b mutually overlaps with the other intersection portion 7b, 7a.
The most downstream ends of the intersections 7a and 7b are connected to the engine body 1.

Further, the intake pipe intersections 7a and 7b are mutually connected and reinforced by ribs (not shown), etc., and a connecting member 8 is integrally formed on the upper surface of the intersections 7a and 7b. 8 is the above surge tank 3
are tightened and fixed by bolts 9, and thus the surge tank 3 is fixedly held above between the cylinder groups 2a and 2b. In addition, the connecting member 8
An EGR passage 10 and a blow-by gas passage 11 are formed, and the downstream ends of both passages 10 and 11 are opened to the surge tank 3.

Further, an injection valve mounting port 12 is formed near the downstream ends of the intake pipe intersections 7a and 7b, and a tip nozzle 13a of a fuel injection valve 13 is inserted into the mounting port 12. The upper end of this fuel injection part 13 is inserted into the fuel supply port 14a of the delivery pipe 14, and the delivery pipe 14 is fastened and fixed to the intake pipes 5a and 5b via a stay etc., so that the fuel injection valve 13 is It is pressed and fixed to the intake pipes 5a and 5b.

In this intake device, the above-mentioned intake pipe U-shaped portion 6
a, 6b have cross-sectional shapes such that their upstream ends are flattened in a substantially horizontal direction (see Fig. 3A), and gradually become approximately circular from the upstream ends to the center of the U-shaped portions 6a, 6b. (See Figure 3), U-shaped portions 6a, 6
It is formed so that it gradually becomes substantially horizontally flattened from the center of the cross section 7a, 7b, ie, the lower projection surface of the surge tank 3 (see FIG. 3C). Further, the intake pipe crossing portions 7a and 7b are formed so that their cross-sectional shapes are flat in the substantially horizontal direction. Here, FIG. 3b shows the intake pipe U-shaped portion 6a shown in FIG.
- Each cross-sectional shape when cut at E11 is shown.

Next, the effects will be explained.

In this device, the intake pipe is curved into a U-shape and inclined in the direction of the output shaft of the engine, and then extended into the downward projection plane of the surge tank, and the cross-sectional shape of the intake pipe is approximately flat. The overall height of the engine can be significantly lowered, and the intake pipe can be made long to ensure inertial supercharging of the intake air.

In addition, in this device, when forming the intake pipe into a substantially flat shape, the cross-sectional shape of the intake pipe is gradually made into a perfect circle from the upstream end of the U-shaped portion to the center of the U-shaped portion, and Since the intake pipe is gradually made flat again from the center to the lower projection surface, the intake resistance at the U-shaped portion of the intake pipe does not increase compared to the case where the entire portion is simply formed flat.

Furthermore, in this device, the interior of the surge tank is divided into two parts, and the intake pipes of cylinders with non-consecutive firing orders are connected to each of them, so intake interference can be suppressed, and the influence of the intake pipes upstream of the surge tank can be suppressed. The supercharging effect associated with the pressure oscillation can be obtained, and the output can be increased especially in the low speed range.

Note that the present invention is not limited to the above embodiments, and various modifications and changes are possible.

For example, in the above embodiment, the engine is a 6-cylinder V-type engine, but this may be a multi-cylinder V-type engine other than 6-cylinders, and the type of engine is not limited to the V-type. It can be anything.

Further, in the above embodiments, the surge tank has a partition that defines the inside, but the surge tank does not necessarily need to define the inside, and the partition is not an essential requirement of the present invention.

Furthermore, in the above embodiment, the upstream end openings of the left and right intake pipes were connected to the left and right side walls of the surge tank, respectively, but the connection between the intake pipe and the surge tank was made only on one side of the surge tank. Also, in the above embodiment, the downstream ends of the U-shaped portions of the left and right intake pipes are crossed and connected to the engine, but the downstream ends of the U-shaped portions of the intake pipes do not necessarily need to be crossed; The detailed structure of the intake pipe will naturally vary depending on the type of engine and the number of cylinders, and the detailed structure of the intake pipe shown in the above embodiments is not an essential requirement of the present invention.

[Effect of idea]

As described above, according to the present invention, in a multi-cylinder engine, the surge tank is arranged above the cylinders so that its long axis coincides with the output shaft direction of the engine, and the plurality of intake pipes extending from the sides of the surge tank are connected to each other. It is curved in a U-shape and inclined in the direction of the output shaft of the engine, and its tip side extends into the downward projection plane of the surge tank, and its tip end is connected to the engine body, and the intake pipe is The shape is approximately horizontally flat at the upstream end of the side wall of the surge tank, and the U
Since the shape is gradually formed into a perfect circle toward the center of the U-shaped portion, and gradually flattened in the horizontal direction from the center of the U-shaped portion to the downward projection surface of the surge tank, the overall height of the engine can be significantly reduced. This has the effect of suppressing an increase in intake resistance at the curved portion of the intake pipe.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional plan view of an intake system for a V-type engine according to an embodiment of the present invention, FIG. 2 is a side view of the surge tank and intake pipe U-shaped portion in the above system, and FIG. 3 is a side view of the intake pipe U-shaped section. It is a figure which shows the cross-sectional shape b of each part of the character part a. 1...Engine body, 2a, 2b...Cylinder, 3...Surge tank, 5a, 5b...Intake pipe, 6a, 6b...U-shaped part.

Claims (1)

[Scope of utility model registration request] In a multi-cylinder engine having a plurality of cylinders, a surge tank forming an enlarged part of the intake passage is arranged above the cylinders so that its long axis coincides with the output shaft direction of the engine, and the surge tank is attached to the side wall of the surge tank. The upstream ends of a plurality of intake pipes connecting the tank and the engine body are opened, and each intake pipe is provided with a U-shaped part that curves in a U-shape in the downstream direction from the upstream end and slopes in the direction of the output shaft of the engine. At the same time, each intake pipe on the downstream side of the U-shaped portion is extended into a downward projected plane of the surge tank, the most downstream end of each intake pipe is connected to the engine body, and the intake pipe has a cross-sectional shape. is flattened in a substantially horizontal direction at the upstream end opening into the side wall of the surge tank, gradually becomes approximately circular from the upstream end to the center of the U-shaped portion, and gradually again from the center of the U-shaped portion to the downward projection surface of the surge tank. 1. An intake device for a multi-cylinder engine, characterized in that it is formed to have a flat shape in a substantially horizontal direction.