JPH08218938A - Intake/exhaust port for internal combustion engine - Google Patents

Abstract

PURPOSE: To reduce dispersion in flow path resistance in respective cylinders by forming an opening part into an oblong shape or into an elliptic shape and inclining the major axes of opening parts of ports matching with cylinders in cylinder head both end parts at the predetermined angle. CONSTITUTION: Among the opening parts 42A-42D formed on the side face of a cylinder head 1, in opening parts 42B, 42C matching with cylinders positioned in the center of the cylinder head 1, the major axes L1 of their oblong shapes are arranged in the overall length direction (in the horizontal direction in the figure). In the opening parts 42A, 42D matching with cylinders positioned in both end parts of the cylinder head 1, the major axes L1 are inclined toward the major axes L1 for the opening parts 42B, 42C by the predetermined angle θ. The center of each of the opening parts 42A, 42D, in other words, an intersection of the major axis L1 and a minor axis L2 , is offset toward a cylinder block 2 side, in other words, downward in the figure, as against the major axes L1 for the opening parts 42B, 42C. In this way, flow path resistance based on a curvature of the major axis L1 can be suppressed, and improvement of output of an engine is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in intake and exhaust port shapes of a multi-cylinder internal combustion engine.

[0002]

2. Description of the Related Art The intake and exhaust ports of a multi-cylinder engine are shown in FIG.
~ As shown in FIG. 10, the combustion chamber 10 of the cylinder head 1
And the exhaust port 4 communicating with the side surface of the cylinder head 1
Oval or elliptical openings 42a-42 on the sides of the
On the other hand, the exhaust port 4 having an elliptical cross section is divided into, for example, two circular pipe lines 40 and 41 by the partition wall 11 inside the cylinder head 1 to form a combustion chamber 10 formed in the cylinder head 1. Openings 40A, 4 at the facing position
1B is opened, and valves (not shown) are housed in the openings 40A and 41A.

For example, in a multi-cylinder engine such as an in-line 4-cylinder engine, the openings 42a to 42d formed on the side surface of the cylinder head 1 have their major axis L ₁ (or major diameter) defined as shown in FIG. It is known that one is arranged in the entire length direction (horizontal direction in the drawing), that is, in parallel with a crankshaft (not shown), and the major axis L ₁ of each opening 42 is arranged substantially on the same straight line. .

In such an exhaust port 4, as shown in FIGS. 9 and 10, the cross-sectional shape is changed from the oval opening 42 to the circular openings 40A and 41A, while the openings 42a to 42d are formed. An axis L ₁ ′ connecting the long axis L ₁ and the centers of the openings 40A and 41A is formed substantially parallel to each other.

Further, as shown in FIG. 11, the openings 42a and 42d of the cylinders at both ends and the openings 42c and 42d at the center are formed.
The major axis L ₁ of the engine is offset in the height direction of the engine (vertical direction in the figure) to allow for the handling of the exhaust port, or, as shown in FIG. 12, the openings 42 a-4.
It is known that 2d is offset with respect to the combustion chamber 10 toward the center of the cylinder head 1 and the exhaust port is also taken into consideration.

Although not shown, the intake port has a similar shape and arrangement.

[0007]

However, in the intake and exhaust ports of such a conventional internal combustion engine, a plurality of exhaust manifolds connected to the exhaust ports of each cylinder are assembled to form one exhaust pipe or catalyst. It is necessary to collect them in the converter and efficiently purify the exhaust gas by the catalyst, but as shown in FIG. 8, the exhaust manifolds 5 connected to the exhaust ports 4 of the cylinders at both ends need to be bent to the central portion. The exhaust manifold 5 connected to the openings 42a and 42d is sharply bent with a curvature R in the direction of the major axis L ₁ of the openings 42a and 42d. Therefore, the exhaust gas from the cylinders at both ends of the cylinder head 1 has a greater flow path resistance in accordance with the curvature R, as compared with the exhaust gas from the central cylinder.
There is a problem that the exhaust resistance between the cylinders becomes non-uniform, and the exhaust flow velocity varies. Similarly, in the intake port, the flow path resistance increases due to the curvature R in the direction of the long axis L ₁ . There is a problem that the intake air amount varies.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide an intake / exhaust port of an internal combustion engine capable of reducing variations in flow path resistance between cylinders.

[0009]

SUMMARY OF THE INVENTION A first aspect of the present invention is an intake / exhaust system for an internal combustion engine, which comprises a plurality of cylinders, each of which is provided with a port for communicating an opening formed in a side surface of a cylinder head with a combustion chamber. In the port, the opening is formed into a substantially oval shape or an elliptical shape, and at least the major axis of the opening of the port corresponding to the cylinders at both ends of the cylinder head is inclined at a predetermined angle θ.

In a second aspect based on the first aspect, the inclination angle θ is set so that the cylinder block direction of the minor axis of the opening portion is oriented substantially at the center of the cylinder head.

A third invention is the first or second invention.
In the invention, the openings of the ports corresponding to the cylinders at both ends of the cylinder head are offset toward the cylinder block side with respect to the other openings.

A fourth invention is the first to third inventions.
In any one of the inventions described above, the opening is offset with respect to the combustion chamber toward substantially the center of the cylinder head.

[0013]

Therefore, according to the first aspect of the invention, the opening of the port is formed by forming the opening on the side surface of the cylinder head into a substantially oval or elliptical shape and inclining the major axis of the opening at a predetermined angle θ. By bending the manifold connected to the section with a curvature in the short axis direction, it is possible to guide the manifold to a predetermined position while increasing the curvature in the long axis direction, and in particular, the curvature of the manifold at both ends of the cylinder head. Can be mitigated to reduce the flow path resistance.

According to the second aspect of the present invention, a plurality of manifolds from the respective ports are provided mainly by the curvature in the minor axis direction while relaxing the curvature in the major axis direction of the manifold connected to the opening of the port. The cylinder heads can be gathered at approximately the center.

According to the third aspect of the invention, the openings of the ports corresponding to the cylinders at both ends of the cylinder head are offset toward the cylinder block side with respect to the other openings, so that the manifolds from the openings are provided. When the cylinder heads are assembled at substantially the center, the manifold channel length of the cylinders at both ends of the cylinder head can be reduced.

According to the fourth aspect of the invention, since the opening is offset toward the combustion chamber toward substantially the center of the cylinder head, the manifolds from the openings are located at the substantially center of the cylinder head. In the case of assembling, it is possible to reduce the pipe length of the manifold of the cylinders at both ends of the cylinder head.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A case where an embodiment of the present invention is applied to an exhaust port of an in-line 4-cylinder engine will be described below with reference to the drawings.

As shown in FIGS. 1 to 4, 4A to 4D are exhaust ports communicating with the side surface of the cylinder head 1 and the combustion chamber 10 for each cylinder. These exhaust ports 4A to 4D are side surfaces of the cylinder head 1. Then almost oval (or oval)
While the openings 42A to 42D are formed in the combustion chamber 10, the partition wall 11 is formed in the plurality of circularly formed openings 40 and 41.
To branch through.

As shown in FIGS. 3 and 4, the exhaust ports 4A to 4D have oval openings 42A to 42D as shown in FIGS.
Gradually change from 2 to 2 through the partition wall 11 from the middle.
Circular opening 4 with two exhaust pipes 40 and 41
Open to the combustion chamber 10 as 0A and 41A. An exhaust valve (not shown) is inserted through the openings 40A and 41A.

As shown in FIG. 2, these openings 42A to 42D are arranged offset to the center of the cylinder head 1 with respect to the combustion chamber 10.

Among the openings 42A to 42D formed on the side surface of the cylinder head 1, the openings 42B and 42C corresponding to the cylinder located in the central portion of the cylinder head 1 are provided.
Corresponds to a cylinder positioned at both ends of the cylinder head 1 while the long axis L ₁ of the ellipse is arranged in the entire length direction of the cylinder head 1 (horizontal direction in the drawing), that is, parallel to a crankshaft (not shown). The opened portions 42A and 42D are
Opening 42B the major axis L _1, is inclined at a predetermined angle θ relative to the longitudinal axis L ₁ of 42C, furthermore, the openings 42A, 4
2D center, i.e., the major axis L ₁ and the intersection openings 42B of the short axis L _2, the cylinder than the length axis L ₁ of 42C block 2
Offset to the side, that is, downward in the figure.

The inclination angle θ of the openings 42A and 42D is set so that the short axis L ₂ toward the cylinder block 2 is directed toward the central portion of the cylinder head 1, as shown in FIGS. The axis L1 ′ connecting the centers of the openings 40A, 41A on the combustion chamber 10 side and the long axis L ₁ of the openings 42A, 42D on the side surfaces of the cylinder head 1 are twisted at a predetermined angle α on the same plane. When the axis L ₁ ′ is parallel to the crankshaft, α = θ.

Openings 42A on the side surface of the cylinder head 1
42D has a branch-shaped exhaust manifold 5
A and 5B are connected in an order corresponding to the ignition order and the like.

Of these, the openings 42A and 42D at both ends of the cylinder head 1 are connected to the exhaust manifold 5A branched in a branch shape at substantially the center of the cylinder head 1, while the openings 42A and 42D at the center of the cylinder head 1 are connected. Openings 42B, 4
2C is similarly connected to the branched exhaust manifold 5B, and these exhaust manifolds 5A and 5B are further assembled and connected to a catalyst (not shown).

With the above construction, the operation will be described below.

The openings 42A, 42D are offset with respect to the combustion chamber 10 toward the center of the cylinder head 1, and the centers of the openings 42A, 42D are defined by the openings 42B, 42.
It is offset from the major axis L _{1 of} C toward the cylinder block 2 side, and further, the minor axis L ₂ that directs the openings 42A and 42D toward the cylinder block 2 side is oriented in a predetermined direction toward the central portion of the cylinder head 1. Since the exhaust manifold 5A connected to the openings 42A and 42D at both ends of the cylinder head 1 is inclined at the angle θ, in FIG. 1, the exhaust manifold 5A has a curvature in the short axis L ₂ direction, that is, around the long axis L ₁ . By bending, the exhaust manifold 5A can be arranged substantially linearly at the collecting position 5Ac according to the inclination angle θ.

Here, while the exhaust manifold 5 having an oval or elliptical cross section is bent with a curvature in the major axis L ₁ direction, bending with a curvature in the minor axis L ₂ direction increases the flow path resistance. Will be reduced.

Therefore, the curvature R in the major axis L ₁ direction is increased as compared with the conventional example, and the exhaust ports 4A and 4D at both ends of the cylinder head 1 are connected according to the curvature in the minor axis L ₂ direction. It becomes possible to guide the exhaust manifold 5A to the collecting position 5Ac almost linearly, and to suppress the increase of the flow path resistance due to the curvature R in the major axis L ₁ direction as in the conventional example. Therefore, it is possible to promote the improvement of the engine output and to equalize the flow path resistance between the cylinders, that is, the exhaust resistance to improve the control accuracy of the fuel injection control and the like.

FIG. 5 and FIG. 6 show a second embodiment of the first embodiment.
Exhaust manifolds 5A and 5B in the embodiment are manifold catalysts 6, and other configurations are the same as those in the first embodiment.

Openings 42A-4 of the exhaust ports 4A-4D
Exhaust manifolds 6A to 6D, which communicate with the manifold catalyst 6 disposed at a position corresponding to substantially the center of the cylinder head 1, are connected to the 2D.

Similar to the first embodiment, the curvature of the exhaust manifolds 6A and 6D in the major axis L ₁ direction is set larger than that of the conventional example, while the curvature in the minor axis L ₂ direction is mainly set. Bending toward the catalyst 6 reduces the heat transfer coefficient of the exhaust manifolds 6A to 6D, suppresses an increase in the pipeline length, suppresses heat dissipation from the exhaust gas, and efficiently purifies the exhaust gas. It becomes possible to do.

In the above-mentioned embodiment, the case where the invention is applied to the exhaust port has been described, but although not shown, the case where the invention is applied to the intake port can similarly reduce the flow path resistance, and the flow resistance between the cylinders can be reduced. It is possible to reduce the variation, secure the intake flow rate, promote the output improvement, make the intake amount uniform among the cylinders, and improve the control accuracy of the fuel injection control and the like.

[0033]

As described above, according to the first aspect of the invention, the opening on the side surface of the cylinder head is formed into a substantially oval shape or an elliptical shape, and the major axis of the opening is inclined at a predetermined angle θ. By bending the manifold connected to the opening of the port mainly with respect to the curvature in the short axis direction, the manifold can be guided to a predetermined position while increasing the curvature in the long axis direction. It is possible to reduce the flow path resistance by relaxing the curvature of the manifolds at both ends, and suppress the increase in the flow path resistance due to the curvature R in the long axis direction as in the conventional example, and to reduce the flow path resistance. It is possible to suppress the variation in the flow path resistance between the cylinders, reduce exhaust resistance at the exhaust port, promote engine output improvement, and even out exhaust resistance between cylinders to improve fuel efficiency. It is possible to improve the control accuracy of the injection control and the like, and in an intake port,
By reducing the flow path resistance, it is possible to secure the intake flow rate and promote the output improvement, while making the intake amount uniform among the cylinders and improving the control accuracy of fuel injection control and the like.

According to the second aspect of the invention, a plurality of manifolds from each port are provided mainly by the curvature in the minor axis direction while relaxing the curvature in the major axis direction of the manifold connected to the opening of the port. It can be gathered at approximately the center of the cylinder head, and in particular, by reducing the flow resistance of the manifold connected to the ports at both ends of the cylinder head, the flow resistance between the cylinders is made uniform, and In addition to improving the output and control accuracy by suppressing the pipe length, it becomes possible to efficiently perform exhaust gas purification by the catalyst by suppressing heat dissipation from the exhaust manifold in the exhaust system.

According to the third aspect of the invention, since the openings of the ports corresponding to the cylinders at both ends of the cylinder head are offset toward the cylinder block side with respect to the other openings, the manifolds from the openings are provided. In the case of gathering in the substantially central part of the cylinder head, it is possible to reduce the conduit length of the manifold of the cylinder at both ends of the cylinder head,
Equalizes and reduces the flow resistance between cylinders to equalize the length of each pipe, improve output and control accuracy, and suppress heat release from the exhaust manifold in the exhaust system to suppress exhaust by the catalyst. It becomes possible to perform purification efficiently.

In the fourth aspect of the invention, since the opening is offset toward the combustion chamber toward the substantially central portion of the cylinder head, the manifolds from the respective openings are located at the substantially central portion of the cylinder head. When assembled, it is possible to further reduce the flow path resistance by reducing the conduit length of the cylinders at the cylinder head ends, and suppress the heat dissipation from the exhaust manifold in the exhaust system. As a result, the exhaust gas can be purified more efficiently by the catalyst.

[Brief description of drawings]

FIG. 1 is a schematic side view of an engine showing an embodiment of the present invention.

FIG. 2 is a schematic plan view of the engine.

FIG. 3 is a schematic sectional view of an exhaust port of the same.

4 is a cross-sectional view taken along arrows AA, BB, and CC of FIG.

FIG. 5 is a schematic side view of an engine showing another embodiment.

FIG. 6 is a schematic plan view of the engine.

FIG. 7 is a schematic side view of an engine showing a conventional example.

FIG. 8 is a schematic plan view of the engine.

FIG. 9 is a schematic sectional view of an exhaust port of the same.

10 is a cross-sectional view taken along arrows DD, EE, and FF in FIG.

FIG. 11 is a schematic side view of an engine showing another conventional example.

FIG. 12 is a schematic plan view of the same.

[Explanation of symbols]

1 cylinder head 2 cylinder block 10 a combustion chamber 4A~4D exhaust ports 40A, 41A opening 42A~D opening 5a, 5b exhaust manifold L ₁ short axis L ₂ major axis

Claims (4)

[Claims] 1. An intake / exhaust port of an internal combustion engine, comprising a plurality of cylinders, wherein a port communicating with the combustion chamber and an opening opened on the side surface of the cylinder head is formed for each cylinder. Alternatively, an intake / exhaust port of an internal combustion engine, which is formed in an elliptical shape, and at least a long axis of an opening of a port corresponding to cylinders at both ends of the cylinder head is inclined at a predetermined angle θ. 2. The intake / exhaust of an internal combustion engine according to claim 1, wherein the inclination angle θ is set so that a cylinder block direction of a minor axis of the opening is directed to a substantially central portion of a cylinder head. port. 3. The openings of the ports corresponding to the cylinders at both ends of the cylinder head are offset toward the cylinder block side with respect to the other openings.
Alternatively, the intake / exhaust port of the internal combustion engine according to claim 2. 4. The intake of the internal combustion engine according to claim 1, wherein the opening is offset with respect to the combustion chamber toward substantially the center of the cylinder head. Exhaust port.