JPS63297712A - Valve system of four-cycle engine - Google Patents

Abstract

PURPOSE:To form a large diameter valve capable of utilizing the volume of a combustion chamber to the maximum by providing respective springs for urging respective intake and exhaust bevel valves in the direction of closing valves in positions separated from the valves to urge the springs through a bell crank. CONSTITUTION:Two intake bevel valves 3 are disposed on one side in a combustion chamber 2 of a cylinder head 2, while two exhaust bevel valves 3 are disposed on the other side. And the respective bevel valves 3 are slidably inserted into holding holes 4 of cylinder head 1 respectively, while a retainer 5 is mounted on the upper end. And a tappet 6 is mounted on the retainer 5, while a cam 11 of a cam shaft 10 bears against the tappet 6. On the other hand, a support shaft 7 of cylinder head 1 supports swingably a bell crank 8, and the front end of bell crank 8 bears against the lower surface of retainer 5 while a coiled spring 9 is interposed between the bell crank 8 and the cylinder head 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a valve train for a four-cycle engine suitable for a four-valve type engine.

[Conventional technology and its problems]

For four-stroke engines, 1. As shown in FIGS. 3 and 4, there is a four-valve engine. This engine is
Two intake valves B are provided on one side of the cylinder head leading to one combustion chamber, two exhaust valves C are arranged side by side on the other side, and an ignition plug is arranged in the center. These four-valve engines have a reputation for having a large valve opening area, high intake and exhaust efficiency, and being able to produce high-performance engines. However, two valves B arranged on one side, as shown in Fig. 3,
For cylinder head valve guide E! ! Coil spring F inserted freely into the outside of valve guide E
The tappet G attached to the upper end of the valve B is pushed by the cam J of the camshaft H to open the valve B. In this structure, the outer diameter of the tappet G is larger than the umbrella-shaped portion of the valve B, and the dimension between the two aligned palls 1B becomes larger. For this reason,
This has the disadvantage that valves B and C cannot be created that make maximum use of the volume of combustion chamber A, and valve 81 becomes smaller. For example, see Japanese Patent Publication No. 49-15162. In order to prevent this, there are two intake valves and two exhaust valves that are tilted forward and backward, and are further tilted so that the upper sides are tilted outward on both sides. For example, see Japanese Unexamined Patent Publication No. 59/231121. In this way, by tilting both outwards, it is possible to avoid being restricted by the dimensions of the tappet, but when machining the tappet, the machining angles will be different for each, which greatly increases the machining time and manufacturing cost. There are some inconveniences.

[Purpose of the invention]

In this invention, a spring that biases an umbrella-shaped valve for intake and exhaust in a direction to pinch is installed at a separate location from the valve, and the umbrella-shaped valve is biased to pinch via a bell crank. The purpose of the present invention is to obtain a valve prevention device for a four-cycle engine that can have a large valve diameter that makes maximum use of the combustion chamber volume and can achieve extremely high performance in intake and exhaust efficiency.

[Structure of the invention]

The present invention will be explained below with reference to the embodiments shown in FIGS. 1 and 2.

Two umbrella-shaped intake valves 3 are arranged on one side of one combustion chamber 2 of a cylinder head 1, and two umbrella-shaped exhaust valves 3 are arranged on the other side.

The umbrella-shaped valve 3 is slidably inserted into the holding hole 4 of the valve guide of the cylinder head 1, and a retainer 5 is attached to the upper end. Then, cylinder head 1 is attached to retainer 5.
A slidably guided tappet 6 is attached to the tappet. A bell crank 8 is attached to the support shaft 7 held by the cylinder head 1. Pivotally attached for free movement. The tip of the bell crank 8 is bifurcated and touches the lower surface of the retainer 5. A coiled spring 9 is elastically inserted between the base of the bell crank 8 and the side wall of the cylinder head 1. Therefore, the umbrella valve is biased to open by pushing the upper end retainer 5 upwardly through the bell crank 8 by the spring 9. A cam 11 of a camshaft 10 that rotates in conjunction with the crankshaft is disposed on the upper surface of the tappet 6.

[Action of the invention]

Cam 1 of camshaft 10 linked to the crankshaft
1 pushes down the umbrella-shaped valve 3 against the spring 9 by rotation, thereby opening and opening the umbrella-shaped valve 3.

The spring 9 is arranged on the side of the cylinder head 1 without surrounding the umbrella-shaped valve 3, and biases the umbrella-shaped valve 3 via the bell crank 8. Therefore, the tappet 6 has fewer dimensional restrictions and can have a smaller outer diameter.

Therefore, the distance between the shafts of the two umbrella-shaped valves 3 arranged side by side can be reduced, and the four umbrella-shaped valves 3 can be installed at positions where the volume of the combustion chamber 2 can be utilized to the maximum. thus,
The frontage area of the umbrella-shaped valve 3 for intake and exhaust can be increased, and a high-performance engine with good intake and exhaust efficiency can be achieved.

Moreover, the two umbrella-shaped valves 3 arranged side by side are arranged in parallel,
It is also easy to process.

〔Effect of the invention〕

As explained above, this invention has an umbrella-shaped valve for intake and exhaust that is slidably inserted into a holding hole of a cylinder head, a retainer is attached to the upper end, and a bell is attached to a support shaft held by the cylinder head. The crank is pivoted so that it can swing freely, the tip of the bell crank is placed on the bottom surface of the retainer, a spring is elastically inserted between the base of the bell crank and the cylinder head, and the umbrella-shaped valve is rotated by the spring through the bell crank. Since the tappet is biased in this manner, the size restriction of the tappet attached to the upper end of the umbrella spring is eliminated and the diameter can be reduced. Therefore, it is possible to reduce the distance between the shafts of two umbrella-shaped valves arranged side by side, and the umbrella-shaped valve can be placed in a position where the volume of the combustion chamber can be maximized.
The valve diameter can be increased to create a high-performance engine with a large opening area and good intake and exhaust efficiency. In addition, the two umbrella-shaped valves are arranged in parallel, allowing the cylinder head to be machined at the same time, saving the labor of machining. Additionally, a four-valve system can be used even in small displacement engines with small combustion chambers.

[Brief explanation of drawings]

1 and 2 show an embodiment of the present invention, FIG. 1 is a cross-sectional side view II, FIG. 2 is a partial plan view, FIGS. 3 and 4 show a conventional example, and FIG. 4 is a front view showing the umbrella valve arrangement, and FIG. 4 is a valve arrangement diagram of the combustion chamber. 1... Cylinder head, 3... Umbrella valve, 4...
...Retention hole, 5...Retainer-17...Spindle, 8.
... Bell crank, 9... Spring. For applicant's agent Hiroshi Fujimoto 3 Figure $42

Claims (1)

[Claims] The umbrella-shaped valves for intake and exhaust are slidably inserted into the holding holes of the cylinder head, and a retainer is attached to the upper end.
The bell crank is pivotally attached to the support shaft held by the cylinder head, the tip of the bell crank is placed on the underside of the retainer, and a spring is elastically inserted between the base of the bell crank and the cylinder head to create an umbrella-shaped valve. A valve train for a four-cycle engine, characterized in that it is biased to close via a bell crank by a spring.