JPH0355766Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an improvement in the valve train structure of a four-stroke engine.

[Prior art]

A 4-stroke engine is equipped with an intake valve and an exhaust valve, and the valve mechanism for these valves transmits the rotation of the crankshaft to a camshaft, and the valve cam attached to the camshaft transmits the operating force via a tapepet. is transmitted to the valve stem, opening and closing the valve.

FIG. 1 is a cross-sectional configuration diagram showing the main parts of a valve operating structure in a conventional side valve type engine.

In the figure, 1 is an intake or exhaust valve, 2 is a valve stem provided at the bottom of this valve 1, and the engine body 3
It is supported within a guide hole 4 formed therein.

Reference numeral 5 denotes a spring that is loosely fitted to the end of the valve stem 2, one end of which is in contact with the engine body 3 side, and the other end is in contact with the retainer 6 that is secured to the valve stem 2, so that the retainer 6 is constantly held by its compressive force. , the valve 1 is pressed and biased in the closing direction.

A tappet 7 is provided on the same axis as the valve stem 2 and separate from the valve stem 2, and is slidably supported in a guide hole 8 formed in the engine body 3, and its lower end is fixed to the camshaft 9. The valve drive cam 10 is in contact with the valve drive cam 10.

In the figure, reference numeral 11 denotes a valve seat that is provided opposite the face of the valve 1 at the end of the intake and exhaust passages 12, and on which the valve 1 moves toward and away from the valve seat.

In the above configuration, when the engine is operated,
Each part of the valve train structure is heated and causes thermal expansion.

Even under this thermal expansion, in order for the valve 1 to come into close contact with the valve seat 11 and maintain airtightness, a small gap, that is, a tappet clearance, is set in advance between the valve stem 2 and the tappet 7, and this is necessary. It is considered essential.

[The problem that the idea aims to solve]

However, because of this tappet clearance, there is a collision between the valve stem 2 and the tappet 7 every time the valve 1 operates during engine operation, which causes premature wear on the contact surfaces of the two, resulting in the tappet being damaged. This causes the tappet clearance to be out of order, and also causes a collision sound (tapping sound), which increases the engine noise. Furthermore,
When assembling and servicing the valve train structure, it is necessary to adjust the tappet clearance using a thickness gauge or the like, which is extremely troublesome work.

This idea was created in view of the above points, and provides a valve train structure that eliminates the tappet clearance, eliminates the need for adjustment work, has a simple structure, is easy to assemble, and has excellent maintainability and quietness. This is what I am trying to do.

[Means to solve the problem]

The valve operating structure for a 4-stroke engine according to this invention has an elastic spacer sandwiched between a valve stem and a tappet for driving an intake valve or an exhaust valve provided in a 4-stroke reciprocating engine. In the valve structure, the elastic spacer has a partially constricted shape (in this specification, a partially constricted shape in the diametrical direction in the axial direction) so as not to interfere with the guide hole that guides the elastic spacer even when compressed. The spring constant is such that it has a compressive reaction force less than the mounting load of the valve spring when the valve is closed, and is large enough to secure the desired valve lift amount when the valve is opened.
It is characterized by being constructed from a rubber-like elastic material.

[Effect]

In the valve operating structure for a four-stroke engine according to the present invention having the above configuration, even when the elastic spacer sandwiched between the valve stem and the tappet is compressed when the valve is opened, the elastic spacer partially forms a constricted shape. Since the diameter of the constricted part is mainly expanded, the movement of the tappet can be smoothly transmitted to the valve stem side without interfering with the wall of the guide hole in which the elastic spacer is installed. can.

In addition, since the spring constant of the elastic spacer is set to the above value, when the valve is closed, the valve is smoothly closed regardless of the elastic spacer being inserted, while when the valve is open, the valve is smoothly closed regardless of the elastic spacer being inserted. This makes it possible to smoothly open the valve regardless of the situation.

As mentioned above, even when the elastic spacer is compressed, it does not interfere with the guide hole and is open to areas other than the tappet and valve stem. Since only force is applied, no sudden change occurs in the spring constant of the elastic spacer during the deformation process. Therefore, no impact force is generated at each contact part, and the tappet,
There will be no adverse effect on the smooth operation and lifespan of the valve stem, valve contact parts, and other structures.

〔Example〕

Hereinafter, this invention will be explained based on embodiments illustrated in the drawings.

FIG. 2 is a sectional view of a main part of the valve train structure of this invention, and FIGS. 3a, b, and c are partial views showing an example of application of an elastic spacer.

In the figure, the same parts as in FIG. 1 are designated by the same reference numerals.

In this valve operating structure, an elastic spacer 13 is sandwiched between the valve stem 2 and the tappet 7, and the elastic spacer 13
The two are connected by eliminating tapepet clearance.

The elastic spacer 13 is mainly made of a heat-resistant and oil-resistant rubber elastic material, and is compressed by the spring 5 when the valve is closed. The spring constant must be such that the installation load is below the value of The amount of deflection of the elastic spacer 13 is selected to have a spring constant large enough to ensure a sufficient amount of valve lift even at maximum lift. In other words, the spring constant of the elastic spacer 13 is set to a value that has a compressive reaction force that is less than the mounting load of the valve spring when the valve is closed, and that ensures the desired valve lift amount when the valve is opened. Ru.

In addition, when the elastic spacer 13 is involved in the guide hole 8, the form of the elastic spacer 13 is a partially constricted shape in which the diameter expands in the axial direction (in the embodiment shown in FIG. 2, the diameter expands in the axial center). The central part is constricted in the direction, the third
When the elastic spacer 13 is compressed, It is configured to eliminate interference with the guide hole 8.

In the figure, reference numeral 14 denotes a wear-resistant material used at the joints between the elastic spacer 13, the end face of the valve stem 2, and the end face of the tappet 7 in order to protect the elastic spacer 13 from wear. The size and arrangement are set appropriately, but the elastic spacer 1
Of course, 3 can also function alone.

In this valve operating structure configured as described above, the valve stem 2 operates the tappet 7 via the elastic spacer 13 to open and close the valve, but the elastic spacer 13 is made of a rubber elastic material as described above. Therefore, the elasticity of the elastic spacer 13 can eliminate the tappet clearance. Moreover, even when the elastic spacer 13 is compressed when the valve 1 is opened, a portion of the elastic spacer 13 is formed in a constricted shape, and this constricted portion mainly expands in diameter when compressed. This elastic spacer 13 can smoothly transmit the movement of the tappet 7 to the valve stem 2 side without interfering with (contacting) the wall surface of the guide hole 8. In addition, since the spring constant of the elastic spacer 13 is set to the above-mentioned value, when the valve 1 is closed, the valve 1 is smoothly closed regardless of whether the elastic spacer 13 is inserted.
At the time of opening, it is possible to smoothly bring the valve 1 into the open state regardless of the presence of the elastic spacer 13.

As described above, even when the elastic spacer 13 is compressed, it does not interfere with the guide hole 8 and is open to, or does not contact, anything other than the tappet 7 and the valve stem 2. Since only the force in the axial direction connecting the valve stem 7 and the valve stem 2 is applied, there is no sudden change in the spring constant during the deformation process. Therefore, no impact force is generated at each contacting portion, and there is no adverse effect on the smooth operation, life, etc. of each component such as the contacting portions of the tappet 7, valve stem 2, and valve 1.

〔effect〕

As described above, according to this invention, an elastic spacer made of a rubber elastic material having the above-mentioned structure is interposed between the valve stem and the tappet to eliminate tappet clearance, and under the appropriate elasticity of the elastic spacer. Since the actuating force from the tappet side is smoothly transmitted to the valve stem to open and close the valve, the operation is reliable without being affected by deformation due to thermal expansion and compression force of various parts of the valve train structure. , there is no collision between the valve stem and tappet, there is no wear on the valve stem or tappet end face, so there is no change in function over a long period of time, there is no tappet sound when the valve operates, and it is extremely quiet. Since there is no need to adjust tappet clearance, the structure is simple and engine assembly is easy.
Also, there are effects such as less time and effort during maintenance and excellent workability.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the main parts of a conventional valve train structure, Fig. 2 is a sectional view showing the main parts of the valve train structure of this invention, and Figs. 3 a, b, and c show elastic spacers. It is a partial block diagram which shows an application example. 1... Valve, 2... Valve stem, 3... Engine body,
4... Guide hole, 5... Spring, 6... Retainer, 7... Tappet, 8... Guide hole, 9... Camshaft, 10... Valve train cam, 11... Valve seat,
12... Intake and exhaust passages, 13... Elastic spacer, 14... Wear-resistant material.

Claims (1)

[Claims for Utility Model Registration] In a valve operating structure for a four-stroke engine in which an elastic spacer is sandwiched between a valve stem and a tappet for driving an intake valve or an exhaust valve provided in a four-stroke reciprocating engine, The elastic spacer is formed into a partially constricted shape so that it does not interfere with the guide hole that guides the elastic spacer when compressed, and its spring constant suppresses the compression reaction force that is less than the mounting load of the valve spring when the valve is closed. 1. A valve train structure for a four-cycle engine, characterized in that it is made of a rubber-like elastic material and is large enough to ensure a desired valve lift amount when the valve is opened.