JPH0355764Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a rotation prevention device for a roller tappet in a valve train for an internal combustion engine.

[Conventional technology]

Some valve train systems for internal combustion engines employ roller tappets to reduce friction.
In a roller tappet, a roller is rotatably provided at the lower end of the tappet body, and the roller faces a cam. The movement of the cam is transmitted to the tapepet via rollers. In roller tappets, it is necessary to maintain a constant position of the roller relative to the cam, and therefore a detent device is required. Therefore, a rotation preventing device has been proposed in which an elongated hole is formed in the body of the tappet and a pin is inserted into the elongated hole (see Utility Model Application No. 101402/1983).

[Problem that the invention attempts to solve]

When assembling the pin, it is necessary to regulate the position of the tappet and insert the pin into the elongated hole. However, in order to obtain the function of preventing the tappet from rotating, the dimensions of both are determined so that the pin can be inserted into the elongated hole with a slight gap. Therefore, there is a problem that the workability of inserting the pin is not good.

In order to solve this problem, it has been proposed to open one end of the elongated hole. However, making the elongated holes open is not preferable because it reduces the strength of the tapepet.

Therefore, the object of this invention is to provide a rotation stopper for a roller tappet that can improve the ease of assembly without reducing strength.

[Means for solving problems]

According to this invention, in a valve train for an internal combustion engine in which a detent pin is inserted into an elongated hole extending in the axial direction formed in the body of a roller tappet, a part of the elongated hole into which the detent pin is inserted is assembled. Provided is a rotation stopper device for a roller tappet, which is formed wide so as to sufficiently facilitate insertion of a pin at the time of use, and is characterized in that the wide portion is smoothly connected to the normally wide portion.

[Effect]

When assembling the roller tappet, the pin is inserted into the wide part of the elongated hole, and the roller tappet and pin are assembled.

When using a roller tappet, the tappet slides inside the elongated hole, but since the connection between the wide part and the normal width part is smooth, the pin can slide smoothly against the elongated hole between the two parts. At the same time, it is possible to achieve a rotation prevention function.

〔Example〕

FIG. 3 shows the overall configuration of an embodiment in which this invention is applied to an OHV type valve train. 10 is a cylinder block, 12 is a piston, 13 is a connecting rod, 14 is a cylinder head, and 16 is a valve. The valve 16 is slidably inserted into the valve guide 17. The lower end of the valve spring 18 is hung on the cylinder head 14, and the upper end is hung on a retainer 20 wedged on the end of the valve stem 16a, so that the valve 16 is biased in the valve closing direction. 22 is a rocker arm, which is attached to the rocker shaft 24. One end of the rocker arm 22 faces the upper end of the valve stem, and an adjuster screw 26 is provided at the other end. 27 is a rock nut. Adjustment screw 26 engages the upper end of push rod 28. pushyrod 2
The lower end of 8 is connected to the cam 31 via the roller tappet 30.
is engaged with. As shown in FIG. 1, the roller tappet 30 consists of a body 32 having an open upper end and a roller 34 attached to the closed lower end of the body 32. The body portion 32 is fitted into a cylindrical hole 36 formed in the cylinder block 10 so as to be vertically slidable. A lower end 28a of the push rod 28 is provided to engage with the inner bottom surface 32a of the body portion 32. As shown in FIG. 1, the roller 34 has shaft portions 34' at both ends thereof.
is rotatably supported by the opposing wall 32' of the body portion 32. The rotational movement of the cam 31 is transmitted to the body 30 via the roller 34, which causes the rocker arm 22 to rotate via the push rod 28, thereby causing the valve 1 to rotate.
6 is opened.

The body 32 is used to prevent the roller tappet 30 from rotating.
A long hole 40 extending in the axial direction is formed in the cylinder block 10, and a detent pin 4 is inserted from the outside of the cylinder block 10.
2 is screwed in, and its tip 42a extends to the elongated hole 40 as shown in FIG.

According to this invention, as shown in FIG.
0 forms a wide upper end 40a and a lower end 40b. Lower end portion 40b as a normal width portion
The width Tb of the pin 42 is formed to be slightly larger than the outer diameter A of the tip 42a of the pin 42, so as to exhibit a sufficient rotation prevention function. On the other hand, the width Ta of the upper end portion 40a is sufficiently larger than the outer diameter A of the tip 42a of the pin 42, making assembly easy.

During assembly, the roller tappet 30 is inserted into the cylindrical hole 36, and at this time the hole 10c formed in the cylinder block 10 into which the pin 42 is inserted (FIG. 2)
The insertion position of the roller tappet 30 is determined so that the wide portion 40a of the elongated hole 40 substantially faces each other. Then, the pin 42 is screwed and inserted, and its tip 42a is introduced into the wide part 40a of the elongated hole 40 (the position of the tip 42a of the pin 42 at this time with respect to the elongated hole 40 is shown by the two-dot chain line in FIG. 1). . This operation is easily accomplished because the dimension Ta of the wide portion 40a is sufficiently larger than the outer diameter A of the pin. After that, the roller tappet 30 is inserted into the lower end portion 40b of the elongated hole 40 by the pin 42.
Shift it to the normal position located at . The position of the pin tip 42a at this time is shown by the solid line in FIG. long hole 40
Since the wide portion 40a and the lower end portion 40b are connected by a smooth curve, the tappet 30 can smoothly move to its normal position.

FIG. 4 shows the shape of the elongated hole 40 in another embodiment. Compared to the first embodiment, the wide portion 40a is located at the lower end, which is the opposite arrangement. When the detent pin is inserted, the tappet 30 is located on the upper side and the pin is located within the wide portion 40a. Thereafter, by lowering the tappet 30 to its normal position, the pin is positioned at the narrow upper end portion 40b.

Figure 5 shows an example in which the elongated hole has a wide part 4 in the center.
0a is formed. vertically narrow portions 40b;
40b' is formed. In this case, when the pin is inserted, the tappet is located in the middle, and the pin is inserted into the wide portion 40a. The normal position may be either the upper side or the lower side, and the pin is inserted into the upper end portion 40b or the lower end portion 40b'.

[Effect of idea]

According to this idea, by making the elongated hole partially wider, it is easier to insert the pin, and after the pin is inserted, the tappet can be moved so that the pin is positioned in the normal narrow width part, so that rotation can be completely prevented. It will be done.
Furthermore, since the elongated hole is closed at both ends, sufficient strength can be obtained.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway side view of the roller tappet of this invention. FIG. 2 is a sectional view taken along the - line in FIG. 1. FIG. 3 is an overall configuration diagram of a valve train to which this invention is applied. FIGS. 4 and 5 are diagrams showing shapes of other embodiments of the elongated hole. 16... Valve, 22... Rotsuka arm, 24
...Lotsukashaft, 28...Putsyurodsud,
30...roller tappet, 31...cam, 32...
...Body part, 34...Roller, 40...Elongated hole, 40a
...Wide part, 42...Stopping pin.

Claims (1)

[Scope of utility model registration request] In a valve train for an internal combustion engine in which a detent pin is inserted into an elongated hole extending in the axial direction formed in the body of a roller tappet, a portion of the elongated hole into which the detent pin is inserted is used to prevent the insertion of the pin during assembly. A device for preventing rotation of a roller tappet, characterized in that it is formed wide for sufficient ease, and that the wide portion is smoothly connected to the normally wide portion.