JPH0323741B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a cylinder head structure for a water-cooled engine.

(Prior art) In a conventional water-cooled DOHC engine, multiple cylinders are installed next to each other with the ignition part of the spark plug located in the center of the combustion chamber, and a chamber is formed at the boundary between the cylinder heads of each of the adjacent cylinders. In some cases, a chain for driving a camshaft, which is located above the cylinder head and drives the intake valve and exhaust valve of each cylinder, is housed in the room.

(Problem to be Solved by the Invention) In this water-cooled engine, as described above, a chamber for accommodating the chain is formed at the boundary between the cylinder heads of adjacent cylinders. The cooling water passage formed in the head is divided, and an independent cooling water passage is provided for each cylinder.

Therefore, the cooling water passages of each cylinder are each provided with a separate cooling water inlet and outlet, and the outlets are located at the upper part of the cylinder head and connected to the radiator by a pipe.

Each of the pipes may be connected to the radiator separately, but since this would be complicated, the pipes are assembled into one pipe above the cylinder head cover assembled to the upper end of the cylinder head and connected to the radiator.

However, with this structure, the cylinder head cover and the cooling water outlet pipes of each cylinder will interfere with each other, so when performing maintenance work such as adjusting the valve clearance of the intake and exhaust valves,
Even if an attempt is made to remove the cylinder head cover from the cylinder head with the pipe still attached, it gets stuck on the pipe and cannot be removed.

To solve this problem, the cooling water passages formed in the cylinder head of each adjacent cylinder are communicated by a passage, and one pipe is connected to one side of the cooling water passage to connect to the radiator. However, it is conceivable that this would allow the cylinder head cover to be attached and detached without interfering with the pipe. However, in order to achieve this, the necessary passages must be formed by bypassing the cylinder head cover, which may lead to an increase in the size of the engine and may have a negative impact on the layout and shape of the engine structure around the passages. become.

An object of the present invention is to provide passages that communicate the cooling water passages of the respective cylinders without increasing the size of the engine or adversely affecting the arrangement of engine elements.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the cylinder head structure of the present invention includes a plurality of cylinders arranged next to each other in which the ignition part of the spark plug is located in the center of the combustion chamber. A water-cooled type in which a chamber is formed at the boundary between the cylinder heads of adjacent cylinders, and a camshaft driving chain located above the cylinder head and driving the intake valve and exhaust valve of each cylinder is housed in the chamber. In a DOHC engine, a passage that crosses the chamber is provided through the inside of the loop formed by the chain, and the passage is connected to a passage space on the chain side in the cooling water passage formed in the cylinder head of each adjacent cylinder. Cooling water passages are communicated with each other.

(Example) An example of carrying out the present invention will _be explained with reference to a drawing regarding the cylinder head structure of a water-cooled engine for a motorcycle. They are arranged in a V-shape with two cylinders in the front and rear, and the two cylinders _A1 in the front and rear are arranged adjacent to each other in parallel.

Reference character a is a crankcase which is a component of the engine A, b is a cylinder block which is the same as the crankcase a, c is a cylinder head, and d is a cylinder head cover.

The above cylinder block b and cylinder head c
The two front and rear cylinders _A1 are each made of the same body and have substantially the same structure, so the structure of the cylinder head c is the same as that of the two rear cylinders _A1 .
This will be explained with reference to FIGS. 2 and 3.

1 is a recess formed in the lower surface of the cylinder head c of each adjacent cylinder A ₁ , and the air-fuel mixture is combusted between the recess 1 and the upper end of a piston (not shown) that fits into the cylinder of cylinder block b. A combustion chamber is now formed.

Each of the recesses 1 has a hole 2 facing the center thereof and through which the spark plug is installed perpendicularly to the cylinder head c.
is opened, and an intake port 3 and an exhaust port (not shown) are opened at symmetrical positions across the hole 2, respectively.

4 is an intake valve that opens and closes the intake port 3, and 5 is an exhaust valve that opens and closes the exhaust port, and these intake and exhaust valves 4 and 5 are driven by their own camshafts 6 and 7, respectively. ing.

The camshafts 6, 7 are provided across the upper end of the cylinder head c of each cylinder _A1 , and a bearing member (not shown) is assembled to the cylinder head c and its upper end.
It is rotatably held between the

Reference numerals 8 and 9 indicate sprockets provided at intermediate portions of the camshafts 6 and 7;
9 and a sprocket (not shown) provided on the crankshaft in the crankcase a or a rotating shaft that rotates continuously with the chain 10, the rotation of the crankshaft is controlled. The signal is transmitted to the cam shafts 6, 7, and the shafts 6, 7 are driven to rotate.

11 is a chain 1 for driving the camshafts 6 and 7;
0, and is formed at the boundary between the cylinder heads c of each cylinder _A1 .

12 and 13 are cooling water passages formed in the cylinder head c of each cylinder _A1 , and these cooling water passages 12 and 13 are provided independently for each cylinder _A1 with the chamber 11 in between. It is being

The cooling water passages 12 and 13 are respectively communicated with cooling water passages (not shown) formed in the cylinder block b, and are located along the upper surface side of the combustion chamber, that is, the recess 1, in each cylinder _A1 , and where the spark plug is attached. It surrounds the hole 2 for cooling, and each part is cooled by cooling water.

On the other hand, the cylinder head cover d is approximately H in plane.
It is formed into a mold and is removably attached to the upper end of the cylinder head c using bolts, etc., and the intermediate connecting side _d1 covers the upper surface of the chamber 11, and both side sides _d2 cover the camshafts 6 and 7. It's becoming like that.

Also, each side of the cylinder head cover d
In the notch d ₃ between d ₁ and d ₂ , a spark plug mounting hole 2 that opens on the top surface of the cylinder head c faces approximately vertically, and a spark plug (not shown) to be mounted in the hole 2 is located. It's becoming like that.

Thus, in such a water-cooled engine A, a passage 14 is provided to communicate the cooling water passages 12 and 13, which are provided independently in the cylinder head c of each adjacent cylinder _A1 .

This passage 14 is provided so as to pass through the loop of the chain 10 and cross the middle part of the chamber 11 interposed between each of the cooling water passages 12 and 13, and both ends thereof are connected to the chain in each of the cooling water passages 12 and 13. The passage spaces on the 10 side are connected to each other so that the cooling water passages 12 and 13 are communicated with each other.

The passage 14 that connects the cooling water passages 12 and 13 to each other utilizes the space in the loop formed by the chain 10 as described above, and furthermore, both ends of the passage 14 are connected to each other with the chain 10 in between. Since it is connected to the passage space, it can be provided without increasing the size of the engine, and it does not adversely affect the arrangement and shape of the engine structure around the passage 14, for example, the shape of the ignition part of the cylinder head c. It has no effect on

In the present application, the shape of the recess 1, which influences combustion efficiency, is formed into an ideal dome shape by positioning the recess 1, which serves as the ignition part of the spark plug, in the center of the combustion chamber and standing the spark plug vertically. According to the above structure, even though the passage 14 is provided, there is no interference with the ignition part of the spark plug, so that the shape of the recess 1 can be maintained in an ideal shape.

On the other hand, the means for forming the passage 14 is
Either it is made integral with the wall surface of the cylinder head c where it is installed, or a cylindrical body made of a separate member from the cylinder head c is inserted across the room 11 and over each of the cooling water passages 12 and 13. In either case, the passage 14 itself passes through the loop formed by the chain 10 as described above.

In the embodiment, the latter means is adopted.

That is, a cylindrical member 15 with one end closed is inserted with its open end first through the side wall c ₁ of the intermediate portion of the cylinder head c in one cylinder A ₁ , and the cylinder head c
The cooling water passage 12 of the cylinder head c is connected to the cooling water passage 13 of the cylinder head c on the opposite side across the room 11.

The cylindrical member 15 is inserted into a fluid-tight state through an O-ring 17 at the boundary between the chamber 11 and the cooling water passages 12 and 13, and at an insertion hole 16 that opens in the side wall _c1 of the intermediate portion of the cylinder head c. However, if the diameter of the cylindrical member 15 is constant, there is a risk that the O-ring 17 fitted on the front outer periphery in the insertion direction may be rubbed against the insertion hole 16 and damaged when it is inserted. Therefore, in order to prevent damage to the O-ring 17, the front part of the cylindrical member 15 in the insertion direction is made smaller in diameter than the rear part.

Reference numeral 18 denotes a through hole opened on the closed end side of the cylindrical member 15, through which the one cooling water passage 12 communicates with the other cooling water passage 13.

A pin 19 prevents the cylindrical member 15 from coming off from the insertion hole 16.

As a means for forming the passage 14, the cylindrical member 15 is inserted from the side wall _c1 of the cylinder head c so as to cross the chamber 11.
Since the cylindrical member 15 can be inserted even when the chain 10 housed in the chamber 11 is stretched around the sprockets 8 and 9 of the camshafts 6 and 7 and the sprocket of the crankshaft or rotating shaft, the chain 10
A so-called endless chain can be used as an endless chain.

Note that the passage 1 passing through the loop of the chain 10
When the chain 4 is formed integrally with the wall surface of the cylinder head c, a disassembleable chain 10 is used to make it removable.

Since the cooling water passages 12 and 13 of each cylinder _A1 are communicated with each other through the passage 14 as described above, only one cooling water outlet is required for the cooling water passages 12 and 13. Outlet 20 is cooling water passage 1
Cooling water passage 1 on one side of 2 and 13, that is, on the right side in the drawing
It is provided on the 3 side and opens at the upper surface of the middle part of the cylinder head c, avoiding the cylinder head cover d and facing the notch _d3 thereof.

A pipe 21 is connected to the outlet 20 and communicates with a radiator (not shown), and the cooling water that has passed through each of the cooling water passages 12 and 13 is sent to the radiator through this pipe 21.

Therefore, as described above, the cooling water passage 1 of each cylinder _A1
The engine A
For example, the intake and exhaust valve 4 of each cylinder _A1 ,
When removing the cylinder head cover d to adjust the valve clearance of No. 5, the cover d does not interfere with the pipe 21, and the cylinder head cover d can be removed independently with the pipe 21 attached. can.

(Effects of the Invention) As described above, the present invention utilizes the space inside the loop formed by the chain to pass the passage across the room housing the chain for driving the camshaft,
Further, the passage is connected to a passage space on the chain side in the cooling water passage formed in the cylinder head of each cylinder, so that the cooling water passages are communicated with each other.

Therefore, it is possible to provide a passage that connects the cooling water passages of each cylinder without increasing the size of the engine, and it is also possible to locate the ignition part of the spark plug in the center of the combustion chamber to increase combustion efficiency. , there is no interference with the passage, the ignition plug can be installed vertically, and the ignition part of the combustion chamber can be formed into an ideal dome shape.

[Brief explanation of drawings]

Fig. 1 is a side view showing a water-cooled engine employing the structure of the present invention, Fig. 2 is an enlarged sectional view taken along the - line in Fig. 1, Fig. 3 is a sectional view taken along the - line in Fig. 2, and Fig. 4 is a sectional view taken along the - line in Fig. 2. The figure is a plan view of the cylinder head cover. In the diagram, A...water-cooled engine, _A1 ...cylinder,
c...Cylinder head, d...Cylinder head cover, 4...Intake valve, 5...Exhaust valve,
6, 7...camshaft, 10...chain, 11...
Room, 12, 13...cooling water passage, 14...passage, 20...cooling water outlet, 21...pipe.

Claims (1)

[Claims] 1 A plurality of cylinders with the ignition part of the spark plug located in the center of the combustion chamber are provided next to each other, a chamber is formed at the boundary between the cylinder heads of each of the adjacent cylinders, and a chamber is formed in the chamber above the cylinder head. In a water-cooled DOHC engine that houses a chain for driving a camshaft that drives the intake valve and exhaust valve of each cylinder, a passage that crosses the above-mentioned chamber is provided through the inside of the loop formed by the above-mentioned chain, and the passage is A structure in which the cooling water passages are connected to the passage spaces on the chain side in the cooling water passages formed in the cylinder heads of adjacent cylinders, thereby communicating the cooling water passages with each other.