JPH0791966B2 - Locker arm supporting device for 4-cycle engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a rocker arm for a 4-cycle engine in which intake and exhaust valves are controlled to be opened and closed by one camshaft and one rocker arm. Regarding the shaft support device.

(Prior Art) Valve operating mechanisms called overhead cams for four-cycle engines include those that directly actuate a cam and act on an exhaust valve to control opening and closing, and those that control opening and closing via a rocker arm. There is also one that is configured by using one camshaft and one rocker arm by using both together. The one-camshaft, one-rocker arm system is one in which a camshaft is arranged above one of intake and exhaust valves to directly control the valve and the other valve is controlled via a rocker arm. The advantage is that the structure is simplified.

However, in this case, there is a problem that the circumference of the cylinder head cannot be sufficiently miniaturized because it is necessary to dispose the ignition plug insertion hole and the shaft center of the cam shaft and the rocker arm support shaft so as not to overlap each other. That is, the axis of the rocker arm support shaft is located on the cylinder axis, while the spark plug is inserted in the center of the combustion chamber. Since the gap is set to be large so that a necessary space can be generated, the width of the cylinder head is lengthened.

(Problems to be Solved by the Invention) As described above, in the one-camshaft, one-rocker arm type four-cycle engine, in order to arrange the ignition plug insertion hole and the camshaft or rocker arm support shaft so as not to overlap each other. In order to solve this problem, the present invention solves this problem by making the rocker arm support axis and the spark plug insertion hole axis cross each other and not interfering with each other. The purpose is to reduce the size of.

[Structure of Invention]

(Means for Solving the Problems) In order to achieve the above-mentioned object, the rocker arm pivotal support device for a four-cycle engine of the present invention has a camshaft arranged above one of intake and exhaust valves. In a 4-cycle engine in which one valve is directly controlled to be opened / closed and the other valve is controlled to be opened / closed via a rocker arm, the cylinder head is traversed at a position where it crosses a spark plug insertion hole recessed in the cylinder head. A shaft hole passing through is bored, and the support shaft of the rocker arm is pivotally supported in the shaft hole so as not to project into the insertion hole.

(Operation) With the above-described structure, the rocker arm support shaft is
The length is set so as to be divided at this portion so as not to project into the spark plug insertion hole, and is axially supported between adjacent spark plug insertion holes and between the insertion hole and the cylinder head side wall. Since the shaft hole penetrates, the rocker arm support shaft divided from one of the shaft holes is sequentially inserted, and at the same time the rocker arm is pivotally supported at the time of insertion, and the pin is axially positioned.

In this way, both the rocker arm support shaft and the spark plug insertion hole can be arranged on the cylinder axis, and suction,
It is possible to shorten the width of the cylinder head by setting a narrow space between the exhaust valves.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 3, an intake passage 3 and an exhaust passage 4 are communicated with a combustion chamber 2 of a cylinder head 1, and an intake valve 5 and an exhaust valve 6 are provided respectively. The intake and exhaust valves 5 and 6 are urged by a spring 7 so as to be always closed.

One camshaft 8 is arranged on the upper surface of the cylinder head 1 above the intake valve 5. An intake cam and an exhaust cam 10 are formed in parallel on the camshaft 8, and the intake cam 9 directly contacts the intake valve 5 via a tappet 11.
The exhaust cam 10 is linked to the exhaust valve 5 via a rocker arm 12. The rotation of the camshaft 8 causes the intake and exhaust valves 5 and 6 to open and close at a required timing.

The camshaft 8 is pivotally supported by a lower half bearing hole 13a formed in the upper surface of the cylinder head 1 and an upper half bearing hole 13b formed in the lower surface of the housing cap 14. 15 is a bolt for tightening the housing cap 14. Further, a head cover 16 is attached to the upper surface of the cylinder head 1.

On the other hand, at the center of the combustion chamber 2, an ignition plug 17 is inserted through a bottom of an ignition plug insertion hole 18 formed in the cylinder head 1. The spark plug insertion hole 18 is connected to upper and lower through holes 19 of the housing cap 14, and is further connected to a through hole 20 formed in the head cover 16 via a seal ring 21, and the camshaft 8 surrounded by the head cover 16 and the like. It is isolated from the valve mechanism room 22 that accommodates the above.

Next, a shaft hole 23 is formed in the upper part of the cylinder head 1 at a position where the spark plug insertion hole 18 is crossed and penetrates the cylinder head 1 across the shaft hole 23. That is, the shaft hole 23a formed in the side wall of the cylinder head 1 and the shaft hole 23b formed in the hole wall of the ignition plug insertion hole 18 are formed through one.

Then, the support shaft 24a is pivotally supported across the shaft holes 23a and 23a, and the support shaft 24b is pivotally supported across the shaft holes 23b and 23b.
The rocker arm 12 described above is pivotally supported by 4a and 24b. Support shaft
The lengths of the shaft ends of the shafts 24a and 24b are set so as not to project into the spark plug insertion hole 18, and they are positioned by the pins 25a and 25b so as not to move in the axial direction.

When assembling, the support shafts 24a and 24b are sequentially inserted from one end of the shaft hole 23 and slid to a predetermined position. At this time, the rocker arm 12 is placed so as to hold the rocker arm 12 so that its shaft hole 26 fits the shaft holes 23a and 23b, and at the same time, the rocker arm 12 is pivotally supported.
Reference numeral 27 is an O-ring interposed at the ends of the support shafts 24a and 24b on the side of the spark plug insertion hole 18.

In this way, 1 camshaft, 1 rocker arm, type 4
The rocker arm support shaft of the cycle engine and the spark plug insertion hole can be arranged near the cylinder axis without interfering with each other, and the space between the intake and exhaust valves can be narrowed to make the cylinder head area compact. You can

〔The invention's effect〕

As described above, the rocker arm pivotal support device for a four-cycle engine according to the present invention, in the configuration of the one camshaft and one rocker arm type, has a rocker in a shaft hole that laterally penetrates the cylinder head across the ignition plug insertion hole. The arm support shaft is mounted on the rocker arm.The rocker arm shaft center and the ignition plug insertion hole are both located near the cylinder shaft center. The effect of shortening the interval between the exhaust valves and sufficiently reducing the size of the cylinder head is obtained.

[Brief description of drawings]

1 shows a cylinder head according to an embodiment of the present invention, FIG. 1 is a plan view taken along the arrow BB in FIG. 3, and FIG.
FIG. 3 is a side view taken along the arrow AA in FIG. 1 ... Cylinder head, 2 ... Combustion chamber, 5 ... Intake valve, 6 ... Exhaust valve, 8 ... Camshaft, 12 ... Rocker arm, 18 ... Head cover, 17 ... Spark plug, 18 ... Spark plug insertion hole, 23, 23a, 23b ... Shaft hole, 24
a, 24b ... Rocker arm spindle.

Claims (1)

[Claims] 1. A camshaft is arranged above one of intake and exhaust valves, and one of the valves is directly controlled to be opened and closed, and the other valve is controlled to be opened and closed via a rocker arm. In a 4-cycle engine,
A shaft hole that penetrates the cylinder head is formed at a position across the ignition plug insertion hole that is recessed in the cylinder head, and the spindle of the rocker arm is pivotally supported in this shaft hole so as not to project into the insertion hole. A rocker arm shaft support device for a four-cycle engine.