JPH0372810B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a valve train for an internal combustion engine in which two intake valves and two exhaust valves are provided for each cylinder.

[Conventional technology]

In recent internal combustion engines, in order to improve output etc., each cylinder has two intake valves and two exhaust valves, and these two intake valves and two exhaust valves are opened and closed. In the case where the camshaft for operation is a single camshaft and this is placed between the intake valve and the exhaust valve, the camshaft is used as a camshaft for the intake valve and a camshaft for the exhaust valve. It has advantages such as a simpler structure compared to the two-piece structure.

However, arranging one common camshaft for two intake valves and two exhaust valves in the area between the intake valve and the exhaust valve in this way prevents the electrode part of the ignition plug from burning. The problem is that the camshaft makes it difficult to center the chamber.

Therefore, Japanese Patent Application Laid-Open No. 54-125315 as a prior art proposes two intake valves and two exhaust valves in one cylinder, and a common camshaft for both intake valves and both exhaust valves. In an internal combustion engine disposed between an intake valve and both exhaust valves, the pivoting portion of the swinging arm for each of the intake valves has a cantilever structure, that is, the swinging arms for both intake valves are pivotably supported. dividing the swinging arm shaft at a part between the two swinging arms to form a space in this part;
By tilting the axis of the cover tube with respect to the axis of the cylinder bore so that the cover tube for installing the spark plug is located in this space, it is possible to move the electrode part of the spark plug closer to the center of the combustion chamber. is suggesting.

[Problem to be solved by the invention]

However, in order to bring the spark plug closer to the center of the combustion chamber, the swing arm shaft that pivots both swing arms for both intake valves is separated at the part between the two swing arms. If the pivot parts of both swinging arms are made to have a cantilevered structure, the swinging motion of both swinging arms will be strained, so in addition to increasing power loss, There was a problem in that the diameter of the swinging arm shaft, on which the swinging arm was pivoted in a cantilevered manner, had to be considerably thickened.

Further, as in the prior art, the swing arm shaft for the intake valve is separated between both swing arms,
In the case of a cantilever support structure, each of the two divided swing arm shafts is provided with positioning means such as a step or a snap link to prevent the swing arm from moving in the axial direction. This made the structure complicated.

The present invention avoids forming the swing arms for both intake valves into a cantilever support structure as described above, and simplifies the mounting structure of the swing arms for each of both intake valves and each of both exhaust valves. The purpose of this is to achieve the following: and miniaturization.

[Means to solve the problem]

In order to achieve this object, the present invention provides two intake valves 12 and two exhaust valves 13 in one cylinder so that their axes are inclined in a V-shape with respect to the axis of the cylinder bore when viewed from the side. a common camshaft for the intake valves and the exhaust valves is disposed between the intake valves and the exhaust valves; two swing arms for each of the intake valves; two swing arms for each of the exhaust valves are pivotally supported on respective swing arm shafts disposed on both sides of the camshaft in parallel thereto, and between the two swing arms for the intake valves; A cover tube for attaching the spark plug is arranged in the portion, and the axis of the cover tube for attaching the spark plug is set so that the axis line is approximately between the intake valve swing arm axis and the intake valve spring in a side view. In an internal combustion engine that is inclined outwardly with respect to the axis of the cylinder bore so as to pass through an intermediate portion, both intake valve swing arms on the axis of the intake valve swing arms;
When the two exhaust valve swinging arms on the exhaust valve swinging arm axis are viewed from above, the two exhaust valve swinging arms are arranged on the inside and the two intake valve swinging arms are located on the outside. , between the two intake valve swing arms and between the two exhaust valve swing arms, each of these swing arms is pressed against a swing arm shaft bearing disposed on the outside thereof. The spring means provided between the two exhaust valve swinging arms is a wave-shaped ring-shaped plate spring fitted onto the exhaust valve swinging arm shaft. On the other hand, the spring means provided between the two intake valve swinging arms of both the spring means is constructed as a plate spring curved in a U-shape in plan view, and this plate spring is arranged between the two intake valve swing arms. The structure is such that it is provided at a location on the opposite side of the ignition plug mounting cover pipe across the axis of the valve swing arm shaft.

[Action/effect of the invention]

The present invention is configured as described above, so that
It has the following effects.

The axis of the ignition plug and its cover pipe in the cylinder is inclined with respect to the axis of the cylinder bore so that the axis passes through a position approximately midway between the swinging arm axis for the intake valve and the spring provided on the intake valve. Although the electrode part of the ignition plug can be brought closer to the center of the combustion chamber, the swing arm shaft for pivoting the swing arms of each of the intake valves is not changed as in the prior art. Since there is no need to separate the two swing arms at the portion between them, it is possible to avoid having both the swing arms for the intake valve in a cantilever support structure.

As a result, in an internal combustion engine having two intake valves and two exhaust valves, in order to install the spark plug in the center of the combustion chamber, a swing arm for both intake valves is required as in the prior art. Since it is possible to avoid a cantilever support structure and to support the swinging arms of both intake valves and both exhaust valves with a support structure at both ends, power loss due to distortion in the swinging motion of each swinging arm can be avoided. It is possible to prevent an increase in the number of parts and a decrease in durability, and also to reduce the number of parts.

In addition, when the swing arms for both intake valves on the swing arm axis for intake valves and the swing arms for both exhaust valves on the swing arm axis for exhaust valves are viewed from above, the swing arms for both exhaust valves are The swing arms for both intake valves are arranged on the inside so that they are located on the outside,
Between the two exhaust valve swing arms and between the two intake valve swing arms, each of these swing arms is pressed against a swing arm shaft bearing disposed outside thereof. By providing spring means for each, it is sufficient to use only two spring means for urging each swing arm against the swing arm shaft bearing. The number of parts of the spring means for holding the swing arms for both intake valves and the swing arms for both exhaust valves so that they cannot move in the axial direction of the swing arm shaft can be reduced.

Of the two spring means, the spring means provided between the two exhaust valve swinging arms is configured as a wave-shaped ring-shaped plate spring fitted onto the exhaust valve swinging arm shaft. Since the distance between the swinging arms for the valve can be significantly reduced compared to when using a coil spring as the spring means, it is possible to avoid an increase in the width dimension in the axial direction of the camshaft. It is possible to reduce the size and weight of the mechanism and, by extension, the internal combustion engine.

Of the spring means, the spring means provided between the two intake valve swing arms is configured as a leaf spring curved in a U-shape in plan view, and this leaf spring is connected to the intake valve swing arm. By configuring the spring means to be provided on the opposite side of the ignition plug mounting cover pipe across the axis of the shaft, the spring means can be used as a spring means, for example, as described in European Patent Publication No.
As described in Publication No. 0141527, the ignition plug mounting cover can be brought closer to the intake valve swing arm shaft than in the case where the coil spring is fitted on the swing arm shaft. The lateral width of the valve mechanism can be reduced by that amount, contributing to further downsizing and weight reduction of the internal combustion engine.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 indicates a cylinder bore 2 inside.
3 is a cylinder head joined to the upper surface of the cylinder block 1, and 4 is a cylinder head detachably attached to the upper surface of the cylinder head 3 so as to cover the valve mechanism chamber 5. A piston 6 that reciprocates within the cylinder bore 2 is provided in the cylinder bore 2, and a pent roof-type combustion chamber 7 is recessed in the lower surface of the cylinder head 3, and An ignition plug 8 is screwed into the cylinder head 3 approximately at the center of the combustion chamber 7 thereof.

Reference numerals 9a and 9b indicate two intake ports for the one combustion chamber 7; reference numerals 10a and 10b indicate the two intake ports for the one combustion chamber 7;
Similarly, two exhaust ports for one combustion chamber 7 are shown, and both intake ports 9a, 9b and both exhaust ports 10a, 10b are defined by a longitudinal center line 11 passing through the center of the cylinder bore 2 in a plan view of the engine.
On both left and right sides sandwiching a, and the longitudinal centerline 11
They are located on both sides of the orthogonal center line 11b in the direction perpendicular to a.

A poppet-type intake valve 12 and an exhaust valve 13 are provided at the openings of the intake ports 9a and 9b into the combustion chamber 7 and the openings of the exhaust ports 10a and 10b into the combustion chamber 7, respectively. stem 12
a and 13a are respectively provided so as to protrude into the valve train chamber 5 on the upper surface of the cylinder head 3, and springs 14 and 15 are provided on the stems of each of these valves to respectively hold each valve closed. There is.

In this case, the axis 16 of both the intake valves 12 and the axis 17 of the exhaust valve 13 are arranged in opposite directions by appropriate angles (θ1) and (θ2) with respect to the axis 18 of the cylinder bore 2, as viewed from the side of the internal combustion engine. It is sloping,
That is, both intake valves 12 and both exhaust valves 13 are V-shaped with respect to the axis 18 of the cylinder bore 2.

Reference numeral 19 indicates a single camshaft common to both intake valves 12 and both exhaust valves 13, and the camshaft 19
is pivotally supported in the valve mechanism chamber 5 between the intake valve 12 and the exhaust valve 13 in parallel to the longitudinal centerline 11 of the engine, and in the valve mechanism chamber 5, the intake valve The two swing arm shafts for the cylinder head 3 are arranged so that the swing arm shafts 20 for the exhaust valve and the swing arm shafts 21 for the exhaust valve are parallel to the cam shaft 19 on both sides of the cam shaft 19. Bearing 22
It is pivoted at.

Both intake valves 1 are mounted on the swing arm shaft 20 for the intake valves.
Two swing arms 23 for each of the two exhaust valves 13 are rotatably supported on the swing arm shaft 21 for the exhaust valve. The swinging arm 23 has one end connected to the upper surface of the two intake valve cams 25 on the camshaft 19, and the other end connected to the upper ends of the stems 12a of both intake valves 12 via distance adjusting screws 26. Furthermore, the swinging arm 24 for both exhaust valves has one end attached to the upper surface of the exhaust valve cam 27 on the camshaft 19, and the other end attached to the upper surface of the exhaust valve cam 27 on the camshaft 19 through the distance adjustment screw 28. are in contact with the upper ends of the stems 13a, respectively.

In this case, the swing arms 23 for both intake valves are provided so as to be located outside of the swing arms 24 for both exhaust valves which are arranged adjacent to each other in plan view, and the swing arms 23 for both exhaust valves A ring-shaped plate spring 34 formed in a wave shape is provided between the arms 24 so as to be fitted onto the swing arm shaft 21, and the ring-shaped plate spring 34 allows the swing arms 24 for both exhaust valves to be rotated on both sides. A plate spring 33 curved into a substantially U-shape in plan view is provided between both the intake valve swing arms 23. As a result, both intake valve swinging arms 23 are pressed and biased toward the swinging arm shaft bearings 22 on both sides. In this case, the leaf spring 33 is provided at a portion closer to the camshaft 19 than the axis of the intake valve arm shaft 20, thereby allowing the swing arm 23 for both intake valves and the swing arm 23 for both exhaust valves to swing. The arm 24 is connected to these swing arm shafts 20,
21 in an axially immovable manner.

Reference numeral 29 denotes a cover tube for attaching the spark plug 8 to the cylinder head 3 from the outside of the cylinder head cover 4. is configured to be inclined by an appropriate angle (θ3) with respect to the axis 18 of the cylinder bore 2 so as to pass through a substantially intermediate portion between the intake valve swing arm shaft 20 and the spring 14 of the intake valve 12. .

In this way, the axis 30 of the cover pipe 29 for attaching the ignition plug is arranged so that the axis 30 passes through a portion approximately in the middle between the swinging arm shaft 20 for the intake valve and the spring 14 of the intake valve 12. Said cylinder bore 2
By being inclined by an appropriate angle (θ3) with respect to the axis 18 of the cover tube 29, the axis 30 of the cover tube 29, and thus the electrode portion 8a of the spark plug 8, can be positioned at or near the center of the combustion chamber 7. However, it is possible to avoid dividing the swinging arm shaft 20 for the intake valve between both the swinging arms 23 for the intake valves as in the prior art, and also to separate the swing arm shaft 20 for the intake valve between both swinging arms 23 as in the prior art. Increasing the inter-valve distance between both intake valves 12 when located between the springs 14 in each of the intake valves 12, and the cover pipe 29
This also makes it possible to avoid an increase in the width of the cylinder head 3 that would otherwise occur if the intake valve 12 is located outside the spring 14 of the intake valve 12.

In this case, the swing arm shaft 20 for the intake valve
A recessed portion 31 is carved on the side surface of the recessed portion 31.
If a part of the cover tube 29 is fitted into the recessed portion 31, the length from the swing arm shaft 20 to the distance adjusting screw 26 in the swing arm 22 will be the same as the length in which the cover pipe 29 fits into the recessed portion 31. Since it is shorter, the width dimension of the cylinder head 3 can be reduced, and the swing arm 23 for both intake valves can be moved to the third position.
When the cover pipe 29 is curved inward in the plan view of the figure, the distance between both intake valves 12 can be further reduced. Furthermore, the cover tube 2
A seal ring 32 made of a soft elastic material such as rubber is provided at a portion where the cylinder head cover 9 passes through the cylinder head cover 4.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG.
The figure is a bottom view of FIG. 1, and FIG. 3 is a sectional view of FIG. 1... Cylinder block, 2... Cylinder bore, 3... Cylinder head, 4... Cylinder head cover, 5... Valve train chamber, 7... Combustion chamber, 8
...Spark plug, 9a, 9b...Intake port, 10
a, 10b...exhaust port, 12...intake valve, 1
3... Exhaust valve, 14, 15... Spring, 19... Camshaft, 20, 21... Swinging arm shaft, 22... Bearing, 23, 24... Swinging arm, 29... For installing spark plug Cover tube, 33... U-shaped leaf spring, 34...
...Ring-shaped leaf spring.

Claims (1)

[Claims] 1 Two intake valves 12 and two exhaust valves 13 are provided in one cylinder so that their axes are inclined in a V-shape with respect to the axis 18 of the cylinder bore 2 in side view, and both intake valves 12 A common camshaft 19 for these intake valves 12 and exhaust valves 13 is disposed between the intake valves 12 and both exhaust valves 13, while two swing arms 23 are provided for each of the intake valves 12.
and two swing arms 24 for each of the exhaust valves 13 are pivotally supported on swing arm shafts 20 and 21 disposed on both sides of the camshaft 19 in parallel thereto, and The swing arm 23 for both intake valves
A cover tube 29 for attaching a spark plug is arranged in the part between, and the axis 30 of the cover tube 29 for attaching a spark plug is
The internal combustion engine is configured such that the axis 30 is inclined outward with respect to the axis 18 of the cylinder bore 2 so that the axis 30 passes through a substantially intermediate portion between the intake valve swing arm shaft 20 and the intake valve spring 14 in a side view. In institutions,
The swinging arms 23 for both intake valves on the swinging arm shaft 20 for intake valves and the swinging arms 24 for both exhaust valves on the swinging arm shaft 21 for exhaust valves are shown in a plan view. The swing arm 24 is arranged so that the swing arm 23 for both intake valves is located on the outside, and the swing arm 23 for both intake valves
and between both the exhaust valve swinging arms 24, for pressing each swinging arm 23, 24 against a swinging arm shaft bearing 22 disposed outside thereof. Each spring means is provided between the two exhaust valve swinging arms 24, and the spring means provided between the two exhaust valve swinging arms 24 is connected to the exhaust valve swinging arm shaft 21.
The spring means provided between the two intake valve swing arms 23 is a plate spring 34 that is curved into a U-shape in plan view. The plate spring 33 is configured as a spring 33, and the leaf spring 33 is connected to the intake valve swing arm shaft 20.
A valve operating device for an internal combustion engine, characterized in that it is provided at a location opposite to the spark plug mounting cover pipe 29 across the axis of the valve.