JPS62243945A - Cylinder head structure for engine - Google Patents

Abstract

PURPOSE:To reduce the relative angle between intake and exhaust valves by securing a head over to the upper portion of a cylinder head while providing an intake port between an intake cam and an exhaust cam in the head cover and arranging an ignition plug at the circumferential side of a combustion chamber. CONSTITUTION:An intake port 45 and an exhaust port 26 opening to a combustion chamber 22 are provided in a cylinder head body 22 while an intake valve 27 and an exhaust valve 28 are provided at the opening of each port. A head cover 31 is secured to the upper portion of the cylinder head body 21 while an intake cam 36 and an exhaust cam 37 are provided in a head cover 31 and an intake port 25 is arranged between respective cams. Furthermore, ignition plugs 23, 24 are arranged at the circumferential side of the combustion chamber 22. Consequently, the relative angle (a) between respective valves 27, 28 can be reduced and the volume of the combustion chamber 22 is reduced thereby the compression ratio can be increased easily.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention provides an air intake port between an intake cam and an exhaust cam.
[! This article relates to the cylinder head structure of the installed engine.

(Prior art) For example, in the engine of a racing vehicle, in order to reduce the intake resistance of the engine, an intake port is arranged between an intake cam and an exhaust cam to alleviate the curvature of the intake port. may be done.

In such a case, in the conventional II 4 precepts, as shown in FIG.
3 and exhaust port 14 at m1, each port 13.1
In addition to the general configuration in which an intake valve 15 and an exhaust valve 16 for opening and closing each port 13.14 are provided at the opening of the port 4,
A configuration is adopted in which an intake port 13 is further arranged between the intake cam 17 and the exhaust cam 18.

For this reason, not only the spark plug 11 but also the intake port 13 are placed in the shadow between the intake cam 17 and the exhaust cam 18, making it impossible to reduce the relative angle α between the valves 15 and 16.

Further, in the conventional configuration described above, the head cover for the intake cam 17 and the head cover for the exhaust cam 18 are formed separately. Furthermore, the upstream side portion of the intake port 13 is made to independently protrude upward, and an intake pipe 19 containing a throttle valve and a fuel injector is connected to the protruding portion.

(Problems to be Solved by the Invention) In the above conventional configuration, the relative angle α of each valve 15.16@
It is difficult to reduce the volume 11 of the combustion chamber 12, and it is difficult to increase the compression ratio. Furthermore, since the intake valve 15 and the exhaust valve 16 tend to interfere with each other, it is not possible to increase the overlap when the valves 15 and 16 are operated. Therefore, even if the intake port 13 is disposed between the intake cam 17 and the exhaust cam 18 in order to reduce intake resistance and improve engine performance, the benefits cannot be fully utilized.

Furthermore, in the above conventional configuration, the head cover for the intake cam 17 and the head cover for the exhaust cam 18 are formed separately, and the intake pipe 19 is independently connected to the upstream portion of the intake port 13 that projects upward. Since they are connected, the sealing area increases, making sealing troublesome, and also increases the number of parts and manufacturing costs.

(Means for solving the problems) (1) Means for solving the problems in the first half of the above; Attach a spark plug that is exposed to the combustion chamber at the bottom of the cylinder head body; An intake port and an exhaust port are provided with an opening of 1°, and an intake valve and an exhaust valve for opening and closing each port are provided at the opening of each port; a head cover is fixed to the upper part of the cylinder head body; the above valve is installed inside the head cover. An intake cam and an exhaust cam to be driven are provided; the intake port is arranged between each cam; the spark plug is arranged closer to the periphery of the combustion chamber than the center of the valve; and the relative angle between each valve is adjusted. This is an engine cylinder head structure characterized by a smaller size.

(2) Measures to solve the problem in the latter half of the above; Attach a spark plug exposed to the combustion chamber at the bottom of the cylinder head body; Provide an intake port and an exhaust port that open to the combustion chamber inside the cylinder head body. , an intake valve and an exhaust valve are provided at the opening of each port to interface each port; a head cover is fixed to the upper part of the cylinder head body; and the above valves are inserted into the head cover. An intake cam and an exhaust cam are provided; the intake port is arranged between each cam, and head covers for the two cams are formed integrally with each other; a part of the intake port is formed within the head cover; and an upper surface of the head cover. This is an engine cylinder head structure characterized by connecting the intake pipe to the cylinder head.

(effect) The spark plug ignites the fuel/air mixture in the combustion chamber.

The fuel-air mixture enters the combustion chamber through the intake port and exits through the exhaust port after combustion.

This intake/exhaust operation is performed as intake valves and exhaust valves driven by an intake cam and an exhaust cam open and close at predetermined timing.

During the intake stroke, since the intake ports are arranged between the respective cams, flow path resistance is small, intake is performed smoothly, and engine performance is improved.

Since the spark plug is arranged closer to the periphery of the combustion chamber than the center of the -F valve and the relative angle between the valves is reduced, there is no need to make a large depression upward in the center of the combustion chamber. Therefore, since the volume of the combustion chamber can be reduced, the compression ratio can be easily increased. Moreover, since the intake valve and the exhaust valve are less likely to interfere with each other when the valves are opened, valve overlap can be easily increased and suitable valve opening/closing timing can be easily obtained.

Since the head covers for the cams in which part of the intake port is formed are integrally formed with each other, the sealing area is reduced and sealing is facilitated.

Moreover, the number of parts is reduced and manufacturing becomes easier.

(Example) As an example, a three-cylinder, four-valve type engine will be described below.

In FIG. 1, there is a slight upward part in the center of the lower surface of the cylinder head main body 21 whose outer peripheral part is fixed to the upper end of the cylinder block (not shown). /υ-shaped combustion chamber 22 is formed. A pair of spark plugs 2 exposed in the combustion chamber 22
3.24 is screwed and fixed within the lower end of the cylinder head body 21.

Furthermore, an intake port 25 and an exhaust port 26 that open into the combustion chamber 22 are provided within the cylinder head body 21. The intake port 25 has a larger diameter than the exhaust port 26, and extends upward within the cylinder head body 21 almost linearly. The exhaust port 26 curves inside the cylinder head body 21 from the combustion chamber 22 side to the left in the figure, and opens at the left end surface of the cylinder head body 21 in the figure. An exhaust pipe (not shown) is connected to the opening.

At the openings of the intake port 25 and the exhaust port 26 on the combustion chamber 22 side, there are an intake valve 27 and an exhaust valve 28 that are generally disc-shaped.
are seated, and in the state shown, each valve 27
．． 28 closes the opening of each port 25,26.

Each valve 27,28 extends upwardly within the cylinder head body 21 at a small relative angle α and is slidably supported therein.

In the illustrated configuration, each pair of the intake port 25 and the intake valve 27 and the exhaust port 26 and the exhaust valve 28 are arranged at a distance in the direction perpendicular to the plane of the paper, and are arranged at a distance W4.
It is a 4-valve type.

As shown in FIG. 2, the intake valve 27 and the exhaust valve 2
8 are arranged symmetrically in pairs in the vertical direction of FIG. One spark plug 23 is located between the intake valves 27 at the circumferential middle of the combustion chamber 22 sandwiched between the intake valves 27.
The combustion chamber 22 is disposed closer to the periphery of the combustion chamber 22 than the center thereof. The other spark plug 24 is arranged in the circumferential middle of the combustion chamber 22 between the exhaust valves 28, closer to the periphery of the combustion chamber 9!22 than the center of the exhaust valve 28.

In FIG. 1, a head cover 31 is fixed to the upper end of the cylinder head main body 21 via a gasket 32 for maintaining airtightness.

The head cover 31 is a generally concave member that looks downward,
A series of cam chambers 33 are formed inside the head cover 31 and the upper surface of the cylinder head body 21 .

Inside the cam chamber 33, a camshaft 34 and a camshaft 35 are arranged which rotate in conjunction with a crankshaft (not shown).

The camshafts 34 and 35 are members extending perpendicularly to the plane of the drawing, and integrally have an intake cam 36 and an exhaust cam 37 at positions corresponding to the respective valves 27 and 28, respectively. The upper ends of the valves 27 and 28 can abut against the intake cam 36 and the exhaust cam 37 via tappet parts 38 and 39, respectively. The spring bearing surface and tappet portion 38 formed on the cylinder head body 21.
A coil spring 40, 41 concentric with the valve 27, 28 is compressed between the coil spring 4 and 39.
By 0.41, the intake valve 27 and the exhaust valve 28
is always elastically biased upward.

The upper end of the intake port 25 opens from the upper end surface of the cylinder head body 21 toward the head cover 31, and the opening is disposed between each cam 36, 37. An intake port 45 is formed in the head cover 31 at a position concentric with the opening. The mating surface of the opening periphery of the intake port 25 and the mating surface of the lower end of the intake port 45 come into contact with each other via a gasket 52 to form a continuous flow path.

The insulator 47 is provided to block vibration and heat. The downstream end of the intake pipe 4 fits into the annular step formed on the upper part of the insulator 47.

As a result, the internal passages of the intake port 25, the intake port 45, and the intake pipe 48 are formed into flow paths having continuous and smooth inner circumferential surfaces. Insulator 47 and intake pipe 4
8 is tightly bound and fixed by a band 49. A fuel injector 50 and a throttle valve 51 are arranged within the intake pipe 48, and the upper end of the intake pipe 48 is open to the outside air. Of course, the upper end of the intake pipe 48 may be connected to an air cleaner.

In this embodiment, a three-cylinder engine is shown as an example, and the ports 45 in the head cover 31 are arranged as shown in FIG. As shown in FIG. 3, three ports 45 are arranged at equal intervals in the crankshaft direction (inward direction). The peripheral edge of the head cover 31 protrudes toward the front in the drawing, and a gasket 32 is disposed at the tip thereof. Since the head cover 31 is integrally formed for the intake cam 36 (FIG. 1) and for the exhaust cam 37 (FIG. 1), the sealing area J on the gasket 32 is smaller than in the past.

Next, the operation will be explained.

When the engine starts, the camshaft 34.35 rotates and each valve 27.35 is driven by a respective cam 36.37.
28 connects the intake port 25 and exhaust port 26 to the combustion chamber 22 at a predetermined timing. This bll
ll requires a certain degree of overlap between the intake valve 27 and the exhaust valve 28, but since the relative angle α is set small, interference between the intake valve 27 and the exhaust valve 28 occurs. hard. Therefore, the overlap between the intake valve 27 and the exhaust valve 28 can be easily set to an optimal value.

The amount of air sucked in from the intake pipe 48 is adjusted by a throttle valve 51 and mixed with fuel from a fuel injector 50. The mixed gas reaches the combustion chamber 22 from the intake pipe 48 through the intake port 45 and the intake port 25, but since the intake port 25 is substantially straight, the flow path resistance is small and the gas flow is smooth.

The mixed gas that has reached the combustion chamber 22 is ignited by the spark plugs 23, 24 at a predetermined timing, and the combusted gas is discharged to the outside from the exhaust port 26. During combustion, the mixed gas is compressed within the combustion chamber 22 by a piston (not shown). Since the relative angle α is set small,
Since the upper center of the combustion chamber 22 is shaped so as not to be depressed upward much, it is easy to make the combustion chamber 22 sufficiently narrow. This allows the compression ratio to be easily increased and high output to be obtained.

(Another Embodiment) (a) The present invention is not limited to being employed in a 3-cylinder, 4-valve type engine, and can be appropriately employed in a single-cylinder or other multi-cylinder engine. Also, 2
It can also be used in valve type engines.

(b) In the case of a single cylinder, there is no interference between adjacent cylinders, so the spark plugs 23 and 24 are connected to the imaginary line (two-dot chain line) in Figure 2.
It is also possible to arrange it at the position shown in , that is, between the intake valve 27 and the exhaust valve 28 .

The spark plug 23.24 is arranged in the circumferential middle of the combustion chamber 22 sandwiched between the adjacent intake valve 27 and exhaust valve 28, and closer to the periphery of the combustion chamber 22 than the center of both valves 27.28. There is.

(C) The configuration is not limited to providing one pair of spark plugs 23, 24, and, for example, a configuration may be adopted in which only one of the spark plugs 23, 24 is provided.

(Effect of the invention) The spark plugs 23 and 24 exposed to the combustion chamber 22 are attached to the lower part of the cylinder head body 21;
1, an intake port 25 and an exhaust port 26 that open to the combustion chamber 22 are provided, and an intake valve 27 and an exhaust valve 28 that open to each port 25.26 are provided at the opening of each port 25.26; A head cover 31 was fixed to the upper part of the cylinder head body 21; an intake cam 36 and an exhaust cam 37 for driving the valves 27 and 28 were provided inside the head cover 31; the intake port 25 was arranged between each cam 36 and 37; As a result, the intake resistance is reduced, intake is performed smoothly, and the engine performance is improved. At the same time, the effect of improving engine performance can be maintained: (1) Effect of the first invention: The spark plugs 23 and 24 are connected to the valves 27 and 27. Each valve 2 is placed closer to the periphery of the combustion chamber 22 than the center of the
Since the relative angle α between 7.28 and 28 is made small, the following effects can be expected.

(a) There is no need to make a large depression upward in the center of the combustion chamber 22. Therefore, since the volume of the combustion chamber 22 can be reduced, the compression ratio can be easily increased and high output can be obtained.

(b) Since the intake valve 27 and the exhaust valve 28 are less likely to interfere with each other when the valves are opened, valve overlap can be easily increased and suitable valve timing can be easily obtained.

(C) This makes it possible to fully utilize the above-mentioned advantage of arranging the intake port 25 between the intake cam 36 and the exhaust cam 37 to improve engine performance.

(2) Effects of the second invention: The cams 36 and 37 are integrally formed with each other; a portion of the intake port 4 is provided in the head cover 31;
Since the intake pipe 48 is connected to the upper surface of the head cover 31, the following effects can be expected.

(a) The sealing area between the cylinder head main body 21 and the head cover 31 is reduced, making the sealing easier.

(b) The number of parts is reduced! FJ construction costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a partial longitudinal cross-sectional view of the cylinder head structure of an engine according to the present invention, FIG. 2 is a partial view taken in the direction of the ■ arrow in FIG. 1, FIG. 3 is a partial cross-sectional view along l1l-1 in FIG. 1 is a partial vertical cross-sectional view of a cylinder head structure of a conventional engine. 21
... Cylinder head body, 22... Combustion chamber, 23.
24...Spark plug, 25.45...Intake port,
26...Exhaust port, 27...Intake valve, 28.
...Exhaust valve, 31...Head cover, 36...
Intake cam, 37...Exhaust cam, 48...Intake pipe

Claims (2)

[Claims] (1) Install the spark plug exposed to the combustion chamber at the bottom of the cylinder head body; provide an intake port and an exhaust port that open into the combustion chamber inside the cylinder head body, and open and close each port at the opening of each port. An intake valve and an exhaust valve are provided; a head cover is fixed to the upper part of the cylinder head body; an intake cam and an exhaust cam for driving the valve are provided within the head cover; the intake port is arranged between each cam; A cylinder head structure for an engine, characterized in that the spark plug is arranged closer to the periphery of the combustion chamber than the center of the valve to reduce the relative angle between the valves. (2) Install the spark plug exposed to the combustion chamber at the bottom of the cylinder head body; provide an intake port and an exhaust port that open into the combustion chamber inside the cylinder head body, and open and close each port at the opening of each port. An intake valve and an exhaust valve are provided; a head cover is fixed to the upper part of the cylinder head body; an intake cam and an exhaust cam for driving the valve are provided within the head cover; the intake port is arranged between each cam; A cylinder head structure for an engine, characterized in that head covers for cams are formed integrally with each other; a part of an intake port is formed within the head cover; and an intake pipe is connected to the upper surface of the head cover.