JPH0422051Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a four-valve single overhead camshaft engine that improves workability in installing and removing spark plugs.

[Conventional technology]

A four-cylinder engine with two intake valves and two exhaust valves per cylinder is used as an engine for automobiles, etc.
Valve type engines have been put into practical use. According to this engine, the intake air filling efficiency and the exhaust efficiency are improved, and the combustion state is improved, thereby realizing high output of the engine. On the other hand, a dual-head camshaft engine in which the intake valve and exhaust valve are driven by different camshafts has also been put into practical use. According to this engine, by eliminating the Rocker arm in the valve mechanism, The reciprocating inertial mass that hinders high engine speeds is reduced, allowing the engine to run at high speeds. However, this double overhead camshaft engine has the disadvantage that the structure is significantly complicated and the cost is high.

Therefore, in the case of an engine that requires high output but does not require particularly high rotation, it is necessary to have two intake valves and two exhaust valves per cylinder, and drive these valves with one overhead camshaft. By doing so, it is possible to secure the required output and reduce costs.

However, in the case of this engine, there are the following problems in arranging the spark plug so as to achieve both ignition performance and serviceability. In other words, in an engine with two intake and two exhaust valves per cylinder, in order to obtain good ignition performance, the four valves are arranged in a square shape with respect to the combustion chamber, and the ignition is carried out in the center of these valves. Although it is necessary to arrange the plug, if there is only one camshaft, the camshaft passes above the center of the combustion chamber, so the camshaft is located directly above the spark plug. Therefore,
The camshaft obstructs the installation and removal of the spark plug, resulting in poor engine serviceability.

For example, in order to solve the above-mentioned problems regarding the 4-valve single overhead camshaft engine,
As shown in Publication No. 102506, by arranging the ignition plug in an inclined manner between two exhaust valves on the side of the exhaust valve where there is a relatively large amount of space, the ignition part at the tip of the ignition plug can be There is one that is located in the center of the combustion chamber and has its upper part facing diagonally upward from the side of the camshaft.

According to this, good ignitability can be obtained, and
It becomes possible to attach and detach the spark plug from diagonally above the camshaft without being obstructed by the camshaft.

By the way, when a spark plug is disposed between two exhaust valves as described above, it is necessary to secure a mounting space for the plug between two exhaust ports located on both sides thereof. In the case of the engine disclosed in the above publication, in order to secure this plug installation space, the two exhaust ports are gradually separated from the opening on the combustion chamber side toward the downstream, so that the planar shape becomes C-shaped. It is set up. As the exhaust ports are separated from each other, the distance between the head bolts disposed on the outside in the crankshaft direction is set wider than the distance between the head bolts on the intake port side.

Such a configuration can be applied without any problem to a single-cylinder engine where there are relatively few restrictions on the dimensions of the engine in the direction of the crankshaft. However, in multi-cylinder engines commonly used for automobiles, increasing the distance between two exhaust ports or the distance between head bolts in the crankshaft direction significantly increases the overall dimension of the engine in the crankshaft direction, so such a configuration is not recommended. It is difficult to apply.

Therefore, in a multi-cylinder 4-valve single overhead camshaft engine, in order to secure the spark plug installation space between the two exhaust valves of each cylinder without increasing the overall dimension of the engine in the crankshaft direction, two It is conceivable to gradually separate the exhaust ports from the opening on the combustion chamber side toward the downstream side, and then bend them in a dogleg shape in a direction in which they become parallel to each other, or in a direction in which they converge.

For example, in Japanese Utility Model Application Publication No. 51-154607, the exhaust ports of adjacent cylinders in the cylinder head are connected to one another.
A configuration in which the exhaust port is merged with the exhaust port of the book is disclosed. With this configuration, the interval between adjacent cylinders can be made as short as possible, and the dimension of the engine in the crankshaft direction can be set short.

[The problem that the idea attempts to solve]

However, although the configuration disclosed in JP-A-57-102506 can shorten the dimension of the engine in the direction of the crankshaft as described above, it requires the installation and removal of the spark plug in a narrow space. This made it difficult to use tools such as a pipe wrench when attaching and detaching the spark plug, and the work efficiency was not very good.

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide an engine structure that allows easy attachment and detachment of a spark plug from the exhaust port side.

[Means to solve the problem]

The four-valve one overhead camshaft engine according to the present invention is provided with two intake valves and two exhaust valves for each cylinder, these valves are driven by one overhead camshaft, and the exhaust valve is driven by one overhead camshaft. Among the exhaust ports that are opened and closed by the engine, adjacent exhaust ports between adjacent cylinders merge in the cylinder head, and one end of the spark plug mounting hole opens in the center of the combustion chamber. ,
In order to solve the above problems, the following measures are taken.

That is, in the four-valve one overhead camshaft engine, the upper part of the stem that opens and closes the exhaust valve is disposed close to the overhead camshaft, and one
Exhaust ports connected to the cylinder and adjacent to each other,
The spark plugs are arranged substantially parallel to each other and extend substantially horizontally to the side wall of the cylinder head, the spark plug mounting hole is arranged in a region formed between the exhaust ports, and the other end is connected to the stem. A head bolt is provided at a height between the upper part of the cylinder head and the opening in the side wall of the cylinder head of the exhaust port, and further includes a head bolt that fixes the cylinder head to the cylinder block in a partition wall that separates adjacent exhaust ports between adjacent cylinders. It is provided with an insertion hole for insertion.

[Effect]

In the above configuration, a large space is formed on the side wall of the cylinder head due to the large distance between the upper part of the stem and the exhaust port. Therefore, a spark plug mounting hole is provided between the exhaust ports arranged almost parallel to each other in one cylinder, and at the height between the top of the stem on the exhaust valve side and the opening in the cylinder head side wall of the exhaust port. By opening the opening, it is possible to handle tools such as a pipe wrench without being hindered by the valve mechanism etc. when attaching and detaching the spark plug, and it is possible to improve workability in attaching and detaching the spark plug.

Also, by providing the spark plug in the above area, it is no longer possible to fasten and fix the cylinder head and cylinder block at this location, but the above fastening and fixing can be done at the partition wall that separates the exhaust ports between adjacent cylinders. Therefore, thermal deformation on the exhaust side of the cylinder head can be suppressed and sealing performance on the exhaust side can be ensured.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

The 4 cylinder 4 valve 1 overhead camshaft engine 1 is
Cylinder block 2 and gasket 3 above it
The cylinder block 2 has a cylinder head 4 fixed thereto, and four vertical cylinders 5 are formed within the cylinder block 2. The engine 1 also includes a piston 6 slidably inserted into each cylinder 5, a space 7a in the cylinder 5 above the piston 6, and a lower surface of the cylinder head 4 that is concentric with and communicates with the space 7a. It has a penta-roof-shaped combustion chamber 7 configured with a cavity 7b recessed in the shape of a shape.

The cylinder head 4 is provided with two intake ports 8 communicating with the combustion chamber 7 from one side thereof, and two exhaust ports 9 communicating with the combustion chamber 7 from the other side thereof. The combustion chamber 7 side openings 8a, 9a of these intake/exhaust ports 8, 9 are connected to the cavity 7.
arranged in a rectangular shape in plan view on the upper surface of b,
They are configured to be opened and closed by intake valves 10 or exhaust valves 11, respectively. Further, the exhaust port 9 is connected to the second exhaust port 9 as soon as it rises from the opening 9a in the cylinder head 4.
It extends almost horizontally to the right in the figure and opens in the side wall of the cylinder head 4.

The intake valve 10 and exhaust valve 11 are
It has stems 10a and 11a that pass through the cylinder head 4 in an inclined manner, and these stems 10
The valve is closed by valve-closing springs 12 and 13 that bias a and 11a diagonally upward of the cylinder head 4. The stem 11a is arranged such that its upper portion is close to the camshaft 17 and stands up significantly with respect to the exhaust port 9. In addition, these intake valves 1
0 and the exhaust valve 11 are connected to the stem 10a,
The corresponding intake cam 15 or exhaust cam 16 is connected to the corresponding intake cam 15 or exhaust cam 16 via the rocker arm 14 that is in contact with the upper end of 11a.
As a result, the valve is driven to open against the valve closing springs 12 and 13. The intake cam 15 and exhaust cam 16
is integrally formed around a single camshaft 17 that is rotatably disposed at the upper part of the cylinder head 4 directly above the center of the combustion chamber 7, and is interlocked and connected to a crankshaft (not shown).

The exhaust ports 9 of each combustion chamber 7 are separated from each other by a short distance downstream from the opening 9a, and beyond this short distance, the exhaust ports 9 of the same cylinder 5 are separated from each other by a wall surface 9b on the side of the other exhaust port 9. The wall surfaces 9c of adjacent cylinders 5 on the exhaust port 9 side are formed so that their tips are connected to each other within the cylinder head 4. As a result, the downstream portions 9d of the exhaust ports 9 of the cylinders 5 adjacent to each other and the downstream portions 9d of the cylinders 5 that are adjacent to each other merge to form a siamese portion.

Between the exhaust ports 9 above is the spark plug mounting hole 1.
8 is provided in an inclined manner. This spark plug mounting hole 18 is a screw hole 18a into which the spark plug 19 is screwed.
and an attachment/detachment hole 18b into which a tool such as a pipe wrench used for plug attachment/detachment is inserted. The spark plug mounting hole 18 is formed so that the end on which the spark plug 19 is inserted opens at a height between the upper part of the stem 11a and the opening in the side wall of the cylinder head 4 of the exhaust port 9. has been done. The axis of the spark plug mounting hole 18 passes through the center of the cavity 7b, and the tip of the spark plug 19 mounted here is positioned at the center of the cavity 7b. It is configured to face diagonally from the side of the exhaust port side of the camshaft 17.

Of the head bolts (not shown), those disposed on the exhaust port 9 side are inserted into insertion holes 2 formed in a wall portion 20 serving as a partition between the exhaust ports 9 that merge with each other.

Further, the ignition order of the engine 1 is, for example,
It is performed in the order of cylinder 5 of 1-3-4-2.

In the above configuration, the exhaust gas flowing out from the opening 9a to the exhaust port 9 is guided by the flesh wall 20 and flows into the exhaust port 9 of the adjacent cylinder 5 without departing from the direction in which it first flows out from the opening 9a. Flowing towards the direction. Therefore, the exhaust resistance is significantly smaller than that in the case where the exhaust port 9 is bent in a dogleg shape and the direction of the exhaust flow is largely deviated from the direction in which it initially flows out from the opening 9a.

Also, the ignition order of engine 1 is 1-3-4-
2, if the negative pressure generated by the pulsation of exhaust gas in the exhaust port 9 of one adjacent cylinder 5 overlaps with the opening of the exhaust valve 11 of the other cylinder 5, combustion will occur with that negative pressure. The exhaust gas is sucked out from the chamber 7, and the exhaust efficiency can be increased.

Furthermore, since there is a large gap between the exhaust port 9 and the stem 11a, the spark plug mounting hole 1 is located on the side wall of the cylinder head 4 on the exhaust port 9 side.
A wide space will be formed around the opening 8. As a result, the handling of tools such as a pipe wrench is not obstructed by the valve mechanism, etc., and the work of attaching and detaching the spark plug 19 can be performed easily.

By the way, by providing the spark plug mounting hole 18 between adjacent exhaust ports of one cylinder, the cylinder block 2 and the cylinder head 4 are connected in this area.
It is no longer possible to fasten and secure the head bolt with the head bolt. However, the insertion hole 2 in the flesh wall portion 20
1 is provided, by inserting the head bolt therein and fastening and fixing it as described above, thermal deformation on the exhaust side of the cylinder head 4 can be suppressed and sealing performance can be ensured.

Note that, even if the two intake ports 8 of each cylinder 5 are formed independently within the cylinder head 4, the present invention is applicable to each cylinder 5.
The same applies even if the two intake ports 8 are branched within the cylinder head 4.

[Effects of the invention] The four-valve single overhead camshaft engine of this invention has
As described above, the upper part of the stem that opens and closes the exhaust valve is located close to the overhead camshaft, and
Exhaust ports connected to the cylinder and adjacent to each other,
The spark plug mounting holes are arranged in a region formed between the exhaust ports, and the other end is arranged in the upper part of the stem. and an opening in the side wall of the cylinder head of the exhaust port, and a head bolt for fixing the cylinder head to the cylinder block is inserted through a partition wall separating adjacent exhaust ports between adjacent cylinders. It has a configuration in which an insertion hole is provided.

As a result, a wide space is formed around the opening of the spark plug mounting hole in the cylinder head, making it easier to handle a tool for attaching and removing the spark plug to the spark plug mounting hole.

Furthermore, by providing a spark plug mounting hole at the above position, it becomes impossible to fasten and fix the cylinder head and cylinder block at this position, but the partition wall formed between the exhaust ports between adjacent cylinders Since the above-mentioned fastening and fixing is performed using the above-described method, sealing performance on the exhaust side can be ensured.

Therefore, if the present invention is adopted, it is possible to improve the workability in installing and removing the spark plug while ensuring the sealing performance between the cylinder head and the cylinder block on the exhaust side.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional plan view of a cylinder head according to an embodiment of the present invention, FIG. 2 is a sectional view of the main part of FIG. 1, and FIG.
The figure is a plan view of the main part. 1 is the engine, 4 is the cylinder head, 9 is the exhaust port, 10 is the intake valve, 11 is the exhaust valve,
17 is a camshaft, 18 is a spark plug mounting hole, 20 is a wall portion (partition wall portion), and 21 is an insertion hole.

Claims (1)

[Claims for Utility Model Registration] One cylinder has two intake valves and two exhaust valves, these valves are driven by one overhead camshaft, and an exhaust port is opened and closed by the exhaust valve. Among these, a multi-cylinder engine in which adjacent exhaust ports between adjacent cylinders merge in the cylinder head, and one end of the spark plug mounting hole opens in the center of the combustion chamber, and the exhaust valve is opened and closed. The top of the stem that
Exhaust ports adjacent to each other and connected to one cylinder are arranged close to the overhead camshaft and are arranged to be substantially parallel and extend substantially horizontally to the side wall of the cylinder head, and the ignition a plug mounting hole is disposed in a region formed between the exhaust ports, the other end opening at a height between the top of the stem and the opening in the cylinder head side wall of the exhaust port; A four-valve single overhead camshaft engine, characterized in that a partition wall separating adjacent exhaust ports between adjacent cylinders is provided with an insertion hole through which a head bolt for fixing the cylinder head to the cylinder block is inserted.