JPH0311108A - Valve system of four cycle engine - Google Patents

Abstract

PURPOSE:To make it possible to lessen the roughness of the internal surface of a combustion room by making the length from the end face of a cylinder head on the side of a combustion room to the shaft center of an inlet camshaft longer than the length to the shaft center of an outlet cam shaft. CONSTITUTION:In an engine 1, the length L from the end face 5a of a cylinder head on the side of a combustion room to the shaft center 21a of an inlet cam shaft 21 is made longer than the length l to the shaft center 32a of an outlet cam shaft 32. This sufficiently separates the cross points of the respective air inlet valves 15 and 15'' which are made to translatingly engage with an inlet cam shaft 21 from the end face 5a on the side of the combustion room. For this reason, the crossing angle between the shaft center 15a of the air inlet valves 15 on both sides and the shaft center 15a' of the middle air inlet valve 15' seeing from the axial direction of the inlet cam shaft 21 becomes small by the distance from the combustion side end face. As a result, the angles alpha'(alpha=alpha') between the end faces 17a and 17a' of valve seats 17 and 17' becomes small. Therefore, the roughness of the internal surface of a combustion room 8.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a valve train S side of a four-stroke engine having at least three intake valves and two exhaust valves.

(Prior art) The valve mechanism of a 4-stroke engine has one example,
There is one disclosed in Japanese Patent No. 7-176311.

According to this, three intake valves for opening and closing an intake port communicating with a combustion chamber are provided in the cylinder head, and an intake camshaft is provided in a cam chamber formed in the upper part of the cylinder head. Each of the intake valves is actuated by direct cam engagement with the intake camshaft, thereby opening and closing the intake port.

In addition, two exhaust valves that open and close the exhaust port leading to the above combustion chamber are provided on the above cylinder head, and these exhaust valves are also directly cam engaged with the exhaust camshaft provided in the above cam chamber. This causes the exhaust port to be opened and closed.

Further, the valve bodies of each of the intake valves are gathered on one side of the inner surface of the combustion chamber, and are arranged in parallel along the substantially circumferential direction of the axis of the cylinder. Therefore, when viewed from the axial direction of the intake camshaft, the axial centers of the intake valves on both sides and the axial center of the intermediate intake valve intersect at a certain angle.

(Problems to be Solved by the Invention) Incidentally, the combustion chamber side end surface of the valve body of each intake valve is perpendicular to the axis of the intake valve. Therefore, if the axes of each intake valve intersect at a certain angle as in the conventional configuration, the angles of the end faces of each valve body will differ from each other by that angle with respect to a certain reference line. .

However, if the angles of the end faces of the valve bodies are different from each other, the inner surface of the combustion chamber becomes uneven, which is unfavorable in terms of engine performance, such as a decrease in combustion efficiency.

Therefore, the upper end of each intake valve is kept in cam engagement with the intake camshaft in a direct-acting manner, and the intersection of the axes of each intake valve (hereinafter simply referred to as The angles of the end faces of the valve bodies are made to match each other as much as possible by locating the intersection point between the axes of the intake valves higher up, that is, by making the angle between the axes of the intake valves as small as possible. is possible.

By the way, if the intersection of the axes of each intake valve is simply positioned upward as described above, the position of the intake camshaft changes upward along with the cam chamber that houses it, but this cam chamber When the position of the exhaust camshaft in the cam chamber changes upward in accordance with this, the exhaust valve is extended upward by that amount.

However, when the exhaust valves are extended in this manner, in addition to the small number of exhaust valves, the inertial weight of each exhaust valve increases, which may impede the desired exhaust action.

(Objective of the Invention) This invention was made in view of the above-mentioned circumstances, and the angles formed by the combustion chamber side end surfaces of the valve bodies of each intake valve are made to match each other as much as possible, thereby improving the inner surface of the combustion chamber. To reduce the unevenness, and even in this case, the inertial weight of the exhaust valve can be kept small, so that the desired exhaust action can be obtained despite the small number of exhaust valves. purpose.

(Structure of the Invention) A feature of the present invention for achieving the above object is that the length from the combustion chamber side end face of the cylinder head to the axis of the intake camshaft is It is at the point where it is longer than the length to the axis of.

(for production) The effects of the above configuration are as follows.

From the combustion chamber side end surface 5a of the cylinder head 5 to the intake camshaft 2
The length up to the axis 21a of 1 is the combustion chamber side end surface 5a of the same.
The length from to the axis 32a of the exhaust camshaft 32! Since the shaft center 15a of each intake valve 15.15' is made longer than the above-mentioned intake camshaft 21,
The intersection point between the two pieces 15a' is sufficiently far away from the combustion chamber side end face 5a. Therefore, when viewed from the axial direction of the intake camshaft 21, the intersection angle α between the axis 15a of the intake valves 15 on both sides of the intake valves 15 and 15' and the axis 15a of the intermediate intake valve +5' is as follows: As described above, the intersection point becomes smaller as the distance from the combustion chamber side end surface 5a increases. As a result, the valve body 17.17 in each intake valve 15°15'
' end face 17a.

The intersecting angle α (α=α) between the 17a' becomes smaller, that is, the unevenness of the inner surface of the combustion chamber 8 becomes less.

In other words, the length from the combustion chamber side end surface 5a of the cylinder head 5 to the axis 21a of the intake camshaft 21 is the same as the length from the combustion chamber side end surface 5a to the exhaust camshaft 32.
The length to the axis 32a! is kept short. Therefore, in order to improve combustion efficiency, the intersection angle α between the axes 15a and 15a' of each intake valve 15 and 15' is
Even if the exhaust valve 27 is made smaller, the length of the exhaust valve 27 is suppressed, and in other words, the increase in the inertial weight of the exhaust valve 27 is suppressed to a small value.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

(First example) 1 to 3 show a first embodiment.

In FIG. 2, 1 is a four-cycle engine mounted on an automobile, and this engine 1 is located in an engine room, and its upper surface is covered by a hood 2. Note that the arrow Fr in the figure indicates the front of the automobile.

1 to 3, 3 is a cylinder of the engine 1, and this cylinder 3 has a cylinder block 4 and a cylinder head 5 mounted on this cylinder block 4. 5 is a flat surface. A piston 6 is slidably fitted into the cylinder block 4, and the piston 6 is connected to a crankshaft (not shown) by a connection l1i7. And the above cylinder block 4
, the cylinder head 5 , and the piston 6 form a combustion chamber 8 6 On the other hand, the upper surface side of the cylinder head 5 is covered with a head cover 9 .
A cam chamber 10 is formed between the tenth face 1 of the cylinder head 5 and the head cover 9.

An intake port 12 is formed at the rear of the cylinder head 5. This intake port 12 is connected to the main port]3 which opens on the rear surface of the cylinder head 5, and this main port 13.
It is composed of three branch ports 14 that branch from the combustion chamber 8 and communicate with the combustion chamber 8.

Three intake valves 2515' that respectively open and close the branch ports 14 that open toward the combustion chamber 8 are provided on the cylinder head 5 so as to be vertically slidable. That is, this intake valve 15.15' has a valve body 17.17' at its lower end that opens and closes the lower end of each branch port 14, and in this case, the axis 15a of each intake valve 15.15' , 15a
and the end surfaces 17a, 17a of the valve body 17.17' on the combustion chamber 8 side.
are orthogonal to each other. And each valve body 17.17
When ' closes each branch port 14 , each end surface 17 a , 17 a ' constitutes a part of the inner surface of combustion chamber 8 .

Each intake valve 15, 15' has a lifter 1 at its upper end.
8.18', and this lifter 18.18' is housed in the cam chamber 10. In addition, each branch port 14
A spring 19 is provided which urges the intake valve 15,15' upwardly to close the lower end of the intake valve 15,15'.

An intake cam shaft 21 is provided within the cam chamber 10 and extends horizontally in the vehicle width direction. This intake camshaft 21 is connected to the cam chamber 10.
It is supported by a cam bearing 22 provided inside, and its axis 21
It is said to be freely rotatable around a. And intake camshaft 2
Three cam noses 23.I are formed at equal intervals in the axial direction.
23' are directly cam-engaged with the corresponding lids 18, 18'.

In FIG. 2, a fuel injection valve 24 for injecting fuel into the intake port 12 is provided. In addition, the same intake port 1
2 has a throttle valve 25 and an intake pipe 25a at its opening to the outside.
, and a surge tank 25b are arranged in series, and the surge tank 25b is located above the head cover 9.

Again, in FIGS. 1 to 3, each intake valve 15.
The axes 15a and 1.5a of the intake camshaft 15' are perpendicular to the axis 21a of the intake camshaft 21, respectively. Further, the openings of the branch ports 14 to the combustion chamber 8 and the valve bodies 17 and 17' that open and close the ports are gathered on the rear side of the inner surface of the combustion chamber 8, and these are located approximately at the axis 3a of the cylinder 3. They are arranged in parallel along the circumferential direction. By the way, for convenience of explanation,
Among the three intake valves 15 and 15', the one in the middle part is indicated with a ``' symbol, such as 15', and this includes the valve body 17', the spear lid 18', and the cam nose 23'.
The same applies to

In particular, in FIG. 3, the center 23a of each cam nose 23 on both sides and the center of the lifter 18, 18 that cam engages with the cam nose 23 are located on the inner side in the vehicle width direction of the axis 15a of each intake valve 15 on both sides. It is deviated to Therefore, the length of the bolt for screwing the cylinder head 5 to the cylinder block 4 can be shortened by the amount by which the center 23a of each cam nose 23 is deviated as described above.

1 and 2, two exhaust ports 26 communicating with the combustion chamber 8 are formed in the front part of the cylinder head 5, and each exhaust port 26 is formed in the cylinder head 5.
Two exhaust valves 27, which open and close the exhaust valves 6 and 6, respectively, are provided to be vertically slidable. The configuration of this exhaust valve 27 is similar to that of the intake valve 15, 15', and has a valve body 28 and a lid 29, and is biased by a spring 30 to close the opening of the exhaust port 26.

Further, an exhaust camshaft 32 is provided in the cam chamber 10 and extends parallel to the intake camshaft 21.This exhaust camshaft 32 is also supported by a cam bearing 33 in the same manner as the intake camshaft 21. The cam noses 34 are cam-engaged with the corresponding lids 29, respectively.

The intake camshaft 21 and the exhaust camshaft 32 are each connected to the crankshaft, and when the engine 1 is in operation, the intake valve 1515' and the exhaust valve 27 are opened and closed as appropriate. be made to work.

In addition, the valve bodies 17 and 17 of each of the above intake valves 15° and 15'
The diameter of ' is smaller than the diameter of the valve body 28 of the exhaust valve 27.

In FIG. 1, the combustion chamber side end surface 5a of the cylinder head 5
The length from the combustion chamber side end surface 5a to the axis 21a of the intake camshaft 21 is sufficiently longer than the length 2 from the combustion chamber side end surface 5a to the axis 32a of the exhaust camshaft 32. Therefore, the intersection point of the axes 15a, 15a' of each intake valve 15, 15' which are directly cam-engaged with the intake camshaft 21 is sufficiently separated from the combustion chamber side end surface 5a.

Therefore, when viewed from the axial direction of the intake camshaft 21, the axis 15a of the intake valves 15 on both sides of the intake valves 15 and 15'
and the axis 15a of the intermediate intake valve +5'.
It gets smaller as it moves away from. As a result, the end face 1 of the valve body 17.17' of each intake valve 15.15'
The intersecting angle α (α=α') between 7a and 17a is reduced, thereby reducing the unevenness of the inner surface of the combustion chamber 8.

In other words, for the length L from the combustion chamber side end 5a of the cylinder head 5 to the axis 21a of the intake camshaft 2I, from the end face 5a of the combustion chamber 0I11 to the axis 32a of the exhaust camshaft 32. The length 2 leading to is kept short.

Therefore, even if the intersection angle α between the axes 15a, 15a' of each intake valve 15, 15' is made smaller as described above in order to improve combustion efficiency, the lengthening of the exhaust valve 27 is suppressed. , the increase in the inertia weight of each exhaust valve 27 is suppressed to a small level.

In the above case, the length of the intake valve 15, 15' is longer than the exhaust valve 27.

Further, among the intake valves 15 and 15', the intake valves 15 on both sides are made longer than the intermediate intake valve 15', that is, the volume of the combustion chamber 8 is designed to be smaller. However, the length of each intake valve 15.15' is from the base circle of the cam noses 23 on both sides to the middle cam nose 23.
' may be made to be the same size as each other.

Further, as described above, the length L from the combustion chamber side end surface 5a to the axis 21a of the intake camshaft 21 is sufficiently long, and accordingly, the overall length of the intake port 2 is increased. For this reason, each branch port 14 branches smoothly from the main port I3.

In FIG. 2, the top surface of the head cover 9 is tilted downward due to the difference in both lengths and β. In order to match this, the upper surface of the surge tank 25b is also tapered. For this reason, the hood 2 can also have a sufficiently downward surface to match the upper surface of the surge tank 25b.

The mating surfaces of the cylinder head 5 and the head cover 9 are aligned with the axis 21a of the intake camshaft 21 and the axis 32a of the exhaust camshaft 32.
It is on an imaginary plane with a downward slope that passes through and. On the other hand, each of the cam bearings 22 and 33 has a cam carrier 36 that is integrally formed on the cylinder head 5 side, and a cam carrier 36 that is integrally formed on the cylinder head 5 side.
The intake camshaft 21 and the exhaust camshaft 32 are sandwiched between the cam carrier 36 and the cam cap 37 and supported as described above. And each of the above cam carriers 36
The base surface of the cam cap 37 is also the cylinder head 5 described above.
and the base surface of the head cover 9 are formed on the same plane. For this reason, since the above-mentioned respective table surfaces can be processed at the same time, this processing is easily performed.

Note that although the above is based on the illustrated example, the intake valve 15.15
' may be four; in this case, there will be two intermediate intake valves 15'. Furthermore, if the surge tank 25b is located on the side of the cylinder 3, the hood 2 can be brought close to the upper surface of the cylinder head 5 and made sufficiently low, as shown by the imaginary line in FIG.

The following figures show the second to fourth embodiments, but their basic configurations and operations are the same as those of the first embodiment.

Therefore, the common configurations will be designated by reference numerals in one drawing and their explanation will be omitted, and only the different configurations will be explained.

(Second example) 4 and 5 show a second embodiment.

In the figure, the axes 18a, 1 of each lifter 18,18'
8a' is perpendicular to the axis 21a of the intake camshaft 21.

On the other hand, the axis 15a of the intake valve 15.15'.

158' is located above the axis 21a of the intake camshaft 21, and therefore the intake valve 15.15
The intersecting angle α between ' is extremely small.

In FIG. 4, passing through the axis 21a of the intake camshaft 21,
Further, a first plane B is a virtual plane perpendicular to the axis 15a of the intake valves I5 on both sides. Further, the intake valve 1 passing through the axis 21a of the intake camshaft 21 and located in the middle
A second plane C is a virtual plane perpendicular to the axis 15a of 5'.

FIG. 5 shows the respective components projected onto the 1,000th plane B for the intake valves I5 on both sides, and onto the second plane C for the intermediate intake valve 15'.

In FIG. 5, the axis 21a of the intake camshaft 21 is perpendicular to the axes 18a, 18a of each lifter 18, 18'. In addition, the axis 15a of the intake valve I5 on both sides,
The axis 15a of the intermediate intake valve 15' is equidistant fiD from the axis 21a of the intake camshaft 21, respectively. In other words, when the intake camshaft 21 cam engages each intake valve 15.15', each intake valve 15.15'
The thrust force generated at ' is made to be the same.

(Third Embodiment) FIGS. 6 and 7 show a third embodiment, in which FIG. 6 corresponds to FIG. 4, and FIG. 7 corresponds to FIG. 5.

According to this, in the plane orthogonal to the axis 21a of the intake camshaft 21, the axis 15a of the intake valves 15 on both sides,
Bisector E with the axis 15a of the intermediate intake valve 15'
The bisector E between the axial center 18a of both side lids 18 and the axial center 18a of the intermediate lid 18' is common, and the axial center of the intake camshaft 21 is located at this trisection gaE. 21a
are orthogonal.

Therefore, the axis 18a of the lid 18 on both sides and the axis 18a' of the intermediate lid 18' are respectively connected to the intake camshaft 21.
They are equidistant F from the axis 21a (bisector E).

Furthermore, in a plane orthogonal to the axis 21a of the intake camshaft 21, the axis 18a of the lid 18 is located on the side of the axis 3a of the cylinder 3, that is, toward the front with respect to the axis 15a of the intake valves 15 on both sides. The axial center 18a' of the lid 18' is deviated from the axial center 15a' of the intermediate intake valve 15' in a direction away from the axial center 3a of the cylinder 3, that is, to the rear. For this reason, each lifter 18, 18' can be provided at a sufficient distance from each other. Therefore, in the cylinder head 5, a sufficient wall thickness can be ensured between the lifter holes into which the respective lifters 18, 18' are fitted.

Note that other symbols A, B, C, and D indicate the same contents as in the second embodiment.

(Fourth example) FIGS. 8 and 9 show a fourth embodiment.

According to this, the axis 15a' of the intermediate intake valve 15'
is perpendicular to the axis 21a of the intake camshaft 21. Also,
In a plane perpendicular to the axis 21a of the intake camshaft 21,
The axis 18a of both side glue lids 18 and the middle glue lid 1
A bisector G between the axis 8' and the axis 18a is perpendicular to the axis 21a of the intake camshaft 21.

Note that other symbols A, B, C, and D indicate the same contents as in the second embodiment.

(Effects of the Invention) According to the present invention, the length from the combustion chamber side end face of the cylinder head to the axis of the intake camshaft is made longer than the length from the combustion chamber side end face to the axis of the exhaust camshaft. The intersection point of the axes of the intake valves that are directly cam-engaged with the intake camshaft is sufficiently separated from the combustion chamber side end surface. Therefore, when viewed from the axial direction of the intake camshaft, the intersection angle between the axial center of the intake valves on both sides and the axial center of the middle intake valve is such that the intersection point is from the end face on the combustion chamber side as described above. It gets smaller as it gets farther away. As a result, the angle of intersection between the end faces of the valve bodies of each intake valve becomes smaller, that is, the unevenness of the inner surface of the combustion chamber is reduced, and combustion efficiency is improved.

In addition, to put the above configuration in another way, the length from the combustion chamber side end surface of the cylinder head to the axis center of the exhaust camshaft is kept short compared to the length from the combustion chamber side end surface of the cylinder head to the axis center of the intake camshaft. ing. For this reason, even if the intersection angle between the axes of each intake valve is reduced as described above in order to improve combustion efficiency, the lengthening of the exhaust valve is suppressed, and the increase in inertia type 1 is kept small. That is, while improving the combustion efficiency, the desired exhaust action by these exhaust valves is ensured despite the small number of exhaust valves.

(Margin below)

[Brief explanation of drawings]

The figures show embodiments of the invention, and Figures 1 to 3 are
An example is shown, and FIG. 1 is a partially enlarged sectional view of FIG.
The figure is an overall side sectional view, Figure 3 is a partial plan view, Figures 4 and 5 are the second embodiment, Figures 6 and 7 are the third embodiment, and Figures 8 and 9 are the third embodiment. , 4 examples are shown, and FIG.
6 and 8 each correspond to a part of FIG. 1, and FIG. 5, FIG. 7, and FIG. 9 each correspond to a part of FIG. 3. 1... Engine, 3a... Axial center, 5... Cylinder head, 5a... Combustion chamber side end surface, 8... Combustion chamber, 15.15'
--Intake valve, 15a, 15a ... shaft center, 21
・・Intake camshaft, 21a・Axis center, 26・・Exhaust port,
27...Exhaust valve, 32...Exhaust camshaft, 32a...
Axial center, αα...intersection angle. Condolence 7 Figure 6 Figure 8 Figure 8 49-

Claims (1)

[Claims] 1. At least three intake valves that open and close the intake port leading to the combustion chamber are provided in the cylinder head, and each of the intake valves is provided with a direct acting type on the end side of the cylinder head opposite to the combustion chamber. An intake camshaft is provided which engages with the cam, and the valve bodies of each of the above-mentioned intake valves are gathered on one side of the inside of the combustion chamber and arranged in parallel along the circumferential direction of the axis of the cylinder, and an exhaust port that communicates with the above-mentioned combustion chamber is provided. In a four-cycle engine, in which two exhaust valves that open and close are provided in the cylinder head, and an exhaust camshaft that cam engages with the exhaust valves is provided in the upper end of the cylinder head, the combustion chamber side of the cylinder head is provided. A valve mechanism for a four-cycle engine in which the length from the end face to the axis of the intake camshaft is longer than the length from the combustion chamber side end face to the axis of the exhaust camshaft.