JP2629262B2 - Multi-cylinder engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a multi-cylinder engine, and in particular, to provide a valve mechanism in a cylinder head, and to open and close intake and exhaust valves provided in each cylinder by the valve mechanism. The invention relates to a configured multi-cylinder engine.

[Conventional technology]

In a multi-cylinder engine, a plurality of cylinders are formed by a cylinder head and a cylinder block, and components such as an intake valve, an exhaust valve, and a spark plug are attached to each cylinder, and the intake and exhaust valves are operated. A valve operating mechanism is provided. In this valve mechanism, each valve stem end of the intake / exhaust valve is pressed by a camshaft rotated by an engine to open / close the intake / exhaust valve.

Further, the difference from the cylinder block of the cylinder head is that the combustion of the air-fuel mixture is substantially completed near the top dead center of the piston, so that the received amount of heat is larger than that of the cylinder block, and there is no sliding portion with the piston or the like. It is mainly made of aluminum alloy casting which is excellent in heat dissipation and lightweight.

A cylinder head is disclosed in Japanese Patent Publication No. 49-15162. The reciprocating internal combustion engine disclosed in this publication realizes an overhead camshaft device that uses a swinging operation for a less severe exhaust valve and performs a cam operation directly on an intake valve to increase the degree of freedom in design. ing.

Another example is disclosed in JP-A-58-135309. Hemispheric combustion chamber cross flow V disclosed in this publication
Type valve center spark plug SOHC engine
Two cams are provided on one camshaft, and one cam opens and closes an exhaust valve, and the other cam opens and closes a suction valve via a rocker arm.

[Problems to be solved by the invention]

In a conventional multi-cylinder engine, the same number of intake valves and exhaust valves are provided for each cylinder.

For this reason, in a multi-cylinder engine with a carburetor specification,
There is a disadvantage that the distribution efficiency of the intake air varies due to the shape of the intake manifold, and the exhaust efficiency varies between the cylinders due to the shape of the exhaust manifold, so that the performance is restricted by the shape of the intake and exhaust manifolds.

Further, in a specific cylinder of a multi-cylinder engine, for example, a cylinder on a flywheel side, there is a disadvantage that the torsion of the crankshaft becomes large and the strength becomes insufficient.

In addition, there is no one in which the number of intake and exhaust valves arranged in each cylinder is different from, for example, two to four, and if the number of intake and exhaust valves is intentionally made different, respectively,
When arranging a desired number of intake and exhaust valves in each cylinder, the layout of the valve operating mechanism is difficult, and there is a disadvantage that the configuration is complicated and the manufacturing cost is increased.

[Object of the invention]

Accordingly, an object of the present invention is to eliminate the above-mentioned disadvantages and to adjust the intake / exhaust efficiency of each cylinder of a multi-cylinder engine comprising a four-stroke engine in order to adjust the intake / exhaust efficiency of each cylinder in the valve operating mechanism according to the manifold shapes of the intake manifold and the exhaust manifold. By making the number of intake and exhaust valves of the cylinders different, the intake and exhaust efficiency can be adjusted between each cylinder, and there is no restriction on the performance due to the intake and exhaust manifold shapes.
An object of the present invention is to realize a multi-cylinder engine that can improve power performance, increase the number of common parts, and reduce costs.

[Means for solving the problem]

In order to achieve this object, the present invention relates to a multi-cylinder engine comprising a four-cycle engine, in which the number of intake and exhaust valves of each cylinder is adjusted according to the shape of the intake manifold and the exhaust manifold to adjust the intake and exhaust efficiency of each cylinder. Is provided with a valve operating mechanism that differs.

[Action]

With the above-described configuration, when the multi-cylinder engine is driven, the intake and exhaust efficiency can be adjusted between the cylinders, and the power performance is not restricted by the intake and exhaust manifold shapes. It is possible to increase the number of common parts and to reduce the cost.

Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings.

1 to 4 show an embodiment of the present invention. In FIG. 2, reference numeral 2 denotes a multi-cylinder engine having four cycles. The multi-cylinder engine 2 is formed by a cylinder head 4 and a cylinder block (not shown), and for example, four first to fourth cylinders 6A, 6B, 6C for burning an air-fuel mixture.
Form 6D.

As shown in FIG. 2, the cylinder head 4 generally has one camshaft 10 on which a cam 8 is mounted, and this camshaft 10 is covered by one cam cap 12.

Also, a cam 8 is provided for each of the first to fourth cylinders 6A, 6B, 6C and 6D.
The upper part of the first rocker arm 14 is provided in contact with the
One end of the first rocker arm 14 is connected to a rocker shaft 16.
And an intake valve 20 for opening and closing the intake passage 18 at the other end. Further, an exhaust valve 26 is provided so that one end of a second rocker arm 22 is in contact with the cam 8, and the other end of the second rocker arm 22 opens and closes an exhaust passage 24.
The valve train 28 is configured.

The valve mechanism 28 includes first to fourth cylinders 6A and 6A.
In order to adjust the intake and exhaust efficiencies of B, 6C, 6D, the number of the intake and exhaust valves 20, 26 of each of the first to fourth cylinders 6A, 6B, 6C, 6D is made different according to predetermined conditions. .

More specifically, the predetermined condition is, for example, a manifold shape of the intake manifold 30 or the exhaust manifold 32 connected to the cylinder head 4 or a degree of torsional strength of a crankshaft (not shown). The number of intake / exhaust valves 20, 26 is changed according to the manifold shape of the exhaust manifold 30 and the exhaust manifold 32 to each of the first to fourth cylinders 6A,
Different for each 6B, 6C, 6D. In other words, the intake manifold
The upstream part of 30 and the downstream part of the exhaust manifold 32,
As shown in FIG. 1, the flywheel 34 side (the right side in FIG. 1)
Is located in the first cylinder 6A, two intake valves 20A-
1 and 20A-2, and two exhaust valves 26A-1 and 2
6A-2 is provided.

Further, two intake valves 20B-1 and 20B-2 are provided in the second cylinder 6B, and one exhaust valve 26B is provided, and two third valves 6C are provided in the third cylinder 6C similarly to the second cylinder 6B. Intake valve 20C-
1, 20C-2 and one exhaust valve 26C are provided.

Further, the fourth cylinder 6D is provided with one intake valve 20D and one exhaust valve 26D.

The fourth cylinder 6D has the best intake / exhaust efficiency among the four cylinders. Therefore, the fourth cylinder 6D is a two-valve type for the purpose of reducing the explosive power in order to compensate for the insufficient torsional strength of the crankshaft.

The first and second rocker arms 14 and 22 for opening and closing the intake and exhaust valves 20 and 26 are connected to the intake and exhaust valves 2 and 3 described above.
It is provided to match the number of 0 and 26.

At this time, in the intake valve 20, the first
The two intake valves 20A-1 and 20A-2 of the cylinder 6A and the second cylinder 6B
The two intake valves 20B-1 and 20B-2 of the third cylinder 6C and the two intake valves 20C-1 and 20C-2 of the third cylinder 6C are formed identically.

In the exhaust valve 26, the two exhaust valves 26A-1 and 26A-2 of the first cylinder 6A are formed identically,
One exhaust valve 26B of the second cylinder 6B and one exhaust valve 26C of the third cylinder 6C
Exhaust valve 26C and one exhaust valve 2 of the fourth cylinder 6D
6D are formed identically.

In addition, the seven first rocker arms 14 are formed identically, and the second rocker arm 22 includes
The second rocker arm 22A-2 of the first cylinder 6A and the second rocker arm 22D of the fourth cylinder 6D are formed identically, and the second rocker arm 22B of the second cylinder 6B and the third cylinder 6B are formed.
The second rocker arm 22C of C is formed identically.

Reference numeral 36 denotes a spark plug, Lc denotes the cylinder head 4
Lp is a center line of a not-shown spark plug mounting hole.

 Next, the operation will be described.

When the multi-cylinder engine 2 is driven, the number of intake / exhaust valves 20, 26 for each of the first to fourth cylinders 6A, 6B, 6C, 6D depends on the shape of the intake / exhaust manifolds 30, 32 and other factors. By adjusting the intake and exhaust efficiencies of each of the first to fourth cylinders 6A, 6B, 6C, and 6D, it is possible to prevent variations in the distribution efficiency of intake air and also prevent variations in exhaust efficiency between cylinders. Power performance can be improved without being restricted by performance due to intake and exhaust manifold shapes.

Further, in the fourth cylinder 6D on the flywheel 34 side, the torsion of the crankshaft (not shown) does not increase, and the strength against the torsion does not occur, which is practically advantageous.

Further, even if the number of intake / exhaust valves 20, 26 disposed in each of the first to fourth cylinders 6A, 6B, 6C, 6D is different from two to four, the intake / exhaust valves 20, 26, Since the first and second rocker arms 14 and 22 or other parts can be shared as much as possible, machining of the cylinder head 4 becomes relatively simple, machining equipment can be inexpensive, and a valve operating mechanism is provided.
This facilitates the layout of the device 28, simplifies the configuration, and can reduce the manufacturing cost.

Furthermore, in a variable-cylinder engine driven by stopping only a specific cylinder, a high-speed type is provided by providing a total of four intake / exhaust valves for the stopped cylinder, and a total of two or three cylinders are always operated If a low-speed type is provided with individual intake / exhaust valves, fuel efficiency and torque during low-speed traveling can be further improved, and mechanical loss can be reduced.

Note that the present invention is not limited to the above-described embodiment, and various application modifications are possible.

For example, in the embodiment of the present invention, the first cylinder is provided with a total of four intake / exhaust valves, and the second and third valves are provided.
The cylinder is provided with a total of three intake / exhaust valves, and the fourth cylinder is provided with a total of two intake / exhaust valves. However, the manifold shape of the intake / exhaust manifold connected to the cylinder head and the twist of the crankshaft are provided. The number of intake / exhaust valves for each cylinder can be varied according to the degree of strength or predetermined conditions consisting of other factors.

In the embodiment of the present invention, a four-cylinder engine has been described as a multi-cylinder engine. However, the present invention can be applied to a three-cylinder engine, a six-cylinder engine, and other multi-cylinder engines.

〔The invention's effect〕

As described in detail above, according to the present invention, the number of intake and exhaust valves of each cylinder is adjusted according to the manifold shape of the intake manifold and the exhaust manifold in order to adjust the intake and exhaust efficiency of each cylinder of a multi-cylinder engine comprising a four-cycle engine. When the multi-cylinder engine is driven, the number of intake and exhaust valves for each cylinder is varied according to the manifold shape of the intake manifold and exhaust manifold, and the intake and exhaust of each cylinder is different. The efficiency can be adjusted, and the distribution efficiency of the intake can be prevented, and the exhaust efficiency between the cylinders can be prevented.Therefore, the power performance is not restricted by the intake and exhaust manifold shapes. Can improve. Further, in a specific cylinder, for example, a cylinder on the flywheel side, it is possible to prevent the torsion of the crankshaft from becoming large, and there is no insufficient strength against the torsion, which is practically advantageous. Furthermore, even if the number of intake / exhaust valves arranged in each cylinder is different from each other, the intake / exhaust valve, the rocker arm, and other parts can be made as common as possible. The processing equipment can be made inexpensive, the layout of the valve operating mechanism can be simplified, the configuration can be simplified, and the manufacturing cost can be reduced.

[Brief description of the drawings]

1 to 4 show an embodiment of the present invention, FIG. 1 is a schematic bottom view of a cylinder head of a multi-cylinder engine, FIG. 2 is an enlarged sectional view of a main part of a cylinder head of a multi-cylinder engine, and FIG. FIG. 4 is a bottom view of the cylinder head of the multi-cylinder engine. In the figure, reference numeral 2 denotes a multi-cylinder engine, 4 denotes a cylinder head, 6A denotes a first cylinder, 6B denotes a second cylinder, 6C denotes a third cylinder, 6D denotes a fourth cylinder, 8 denotes a cam, 10 denotes a camshaft, and 12 denotes a camshaft. Cam cap, 14 is the first rocker arm, 16 is the rocker shaft, 18 is the intake passage, 20 is the intake valve, 22 is the second rocker arm, 24 is the exhaust passage, 26 is the exhaust valve, 28 is the valve operating mechanism, 30 is An intake manifold, 32 is an exhaust manifold, 34 is a flywheel, 36 is a spark plug, Lc is a vertical center line of a cylinder head, and Lp is a center line of a spark plug mounting hole.

Claims (1)

(57) [Claims] In a multi-cylinder engine comprising a four-cycle engine, the number of intake and exhaust valves of each cylinder is varied according to the manifold shape of an intake manifold and an exhaust manifold in order to adjust the intake and exhaust efficiency of each cylinder. A multi-cylinder engine characterized by having a mechanism.