JPH0355770Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] This invention mainly relates to an improvement of a valve tappet interposed between a valve driving cam and a poppet valve of an engine.

[Prior art]

Conventionally, in high-speed internal combustion engines, a cup-shaped tappet is interposed between the valve drive cam and the poppet valve.
Only the component force in the axial direction is applied to the poppet valve from the rotation of the valve cam (for example,
Publication No. 42263). Furthermore, in recent years, the output per unit displacement of internal combustion engines has been further increased, and for this reason three or more intake valves are often used in one cylinder. At this time, if the displacement per unit cylinder is relatively small, the diameter of the cylinder is small, so it may not be possible to accommodate a large number of cup-shaped tappets within that range, and there is a limit to the number of valves. Furthermore, if the tappets are made thinner, it is possible to arrange a large number of tappets, but unless the diameter of the valve drive cam is made smaller, there is a problem that they will come off the cam surface of the valve drive cam.

[Summary of the idea]

This idea is based on an engine that has a cylinder with a circular cross section and a plurality of cup-shaped tappets arranged adjacent to each other, in which three intake valves are arranged per cylinder, and the center intake valve and the intake valves on both sides are arranged side by side. The tappets are provided so as to be inclined at different angles with respect to the axis of the cylinder, and the side faces of each of the tappets facing the adjacent tappets are chamfered, and the tappet that drives the central intake valve is located on the camshaft. It is characterized in that the side surface perpendicular to the direction of rotation is in sliding contact with the guide of the cylinder head, and the chamfered portion is in sliding contact with the tappets on both sides.

〔Example〕

This invention will be explained below with reference to illustrated embodiments. In the figure, 1 indicates the cylinder head of an overhead cam type engine. The cylinder head 1 is provided with an intake passage 2 and an exhaust passage 3 communicating with the combustion chamber wall on the lower surface, and an intake valve 4 and an exhaust valve 5 are provided at the openings of these passages. Note that three intake valves 4 are provided per cylinder, and the intake valve 4 located in the center is
As shown by the broken line in FIG. 1, the valve stem angle is different from those on both sides. 6 is a valve spring for seating each valve 4, 5 on a valve seat.

An intake camshaft 7 and an exhaust camshaft 8 are provided above the cylinder head 1. 9 is each valve 4,5
This is a cup-shaped tappet interposed between the valve cams 7a and 8a. As is clear from FIG. 2, several cup-shaped tappets 9 are provided adjacent to each other, and their adjacent sides are chamfered to form an oval or substantially semi-cylindrical shape in a plan view.
Each chamfered portion touches each other to prevent them from rotating relative to each other.

Here, the guide hole 1a of the cup-shaped tappet 9 formed in the cylinder head 1 is formed in the shape of a gourd, and it is extremely difficult to process it with a boring machine as in the past. teeth,
A separate guide member 10 having three guide holes 1a is fixed thereto. 11 is a wear-resistant member supported on the top of the tappet 9, and 12 is a camshaft driving sprocket, which is driven by the crankshaft via a timing chain.

According to this embodiment, when the engine is started and the valve operating cam 7a rotates, its cam surface rubs and presses the top surface of the cup-shaped tappet 9 along its longitudinal direction. The cup-shaped tappet 9 is the guide hole 1
Move up and down inside a to open and close the intake valve 3.

[Effect of idea]

As explained above, the engine valve tappet according to the present invention has three intake valves arranged side by side per cylinder, and the central intake valve and the intake valves on both sides are set at different angles with respect to the axis of the cylinder. the tappets are provided in an inclined manner, and the side surfaces of each of the tappets facing the adjacent tappets are chamfered;
The tappet that drives the central intake valve has a side surface perpendicular to the direction of rotation of the camshaft that is in sliding contact with the guide of the cylinder head, and a chamfered portion that is in sliding contact with the tappets on both sides, so that adjacent tappets do not touch each other. The distance between the shafts can be made as small as possible while ensuring the width of the portion where the cam surface of the valve drive cam slides. Therefore, it becomes possible to arrange three intake valves in close proximity to each other, with the valve shaft angle of the center valve being changed from that of the valve shaft angles of the valves on both sides, so that the displacement per cylinder can be compared. It is possible to increase the number of valves in an engine with a small cylinder diameter. However, there are no problems such as reducing the diameter of the cup-shaped tappet, which reduces the area of the sliding part of the valve cam, making it impractical, or drastically reducing durability. be.

It should be noted that it is difficult to form the guide hole of the irregularly shaped tappet by directly machining it into the cylinder head as in the embodiment, so it is convenient to form a separate member with the guide hole formed therein as in the embodiment. Further, by bringing the chamfered side surfaces of adjacent tappets 9 into contact with each other, positioning in the circumferential direction can be performed simultaneously.

[Brief explanation of the drawing]

The drawing shows one embodiment of this invention.
The figure is a sectional view of the main parts of the engine, and Figure 2 is its -
The sectional view and FIG. 3 are external views of the main parts. 1... Cylinder head, 1a... Guide hole, 7...
...Intake camshaft, 7a... Valve train cam, 8... Exhaust camshaft, 9... Tappet.

Claims (1)

[Scope of utility model registration request] In an engine having a cylinder with a circular cross section and a plurality of cup-shaped tappets arranged adjacently,
Three intake valves are arranged in line for each cylinder, and the central intake valve and the intake valves on both sides are tilted at different angles with respect to the axis of the cylinder,
The tappet that drives the central intake valve has a chamfered side surface facing the other adjacent tappet, and the tappet that drives the central intake valve has a side surface perpendicular to the direction of rotation of the camshaft that is in sliding contact with the guide of the cylinder head. A valve tappet for an engine, characterized in that the chamfered portion is in sliding contact with the tappets on both sides.