JPH041402A - Valve lifter - Google Patents

Abstract

PURPOSE:To exchange easily shims without using a notch by dividing a valve lifter into a first disk-like valve lifter for depressing a valve stem with a press force of a cam and a second cylindrical valve lifter engaging the first valve lifter and vertically moving to open and close a valve. CONSTITUTION:A valve lifter is divided into a first valve lifter 31 and a second valve lifter 32. The first valve lifter 31 is disk-shaped to transmit a press force of a cam 1 to a valve stem 41 through a shim 2 and depress directly a valve 4. Thus, a press force of a first spring 51 is transmitted to the first valve lifter 31 through a retainer 6 and lock 7 so that the first valve lifter 31 engages the cam 1 through the shim 2. On the other hand, the second cylindrical valve lifter 32 is formed with an inward flange part 321 on which is removably mounted the first valve lifter 31. A second spring 52 is seated on the lower surface of the flange part 321 in the second valve lifter 32 to press the second valve lifter 32 against the first valve lifter 31.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a valve train for an internal combustion engine, and particularly to a shim exchange mechanism on a valve lifter.

[Conventional technology]

Conventionally, a valve train for an internal combustion engine has a cup-shaped valve lifter that engages with the tip of a valve stem, and a disc-shaped shim is disposed between the valve lifter and the cam. The gap between the valve lifter and the cam, ie, the tappet clearance, is adjusted. FIG. 4 shows a conventional valve operating system around a valve lifter. When the cam 1 rotates and pushes down the shim 2 and valve lifter 3, the valve 4 opens.
When the valve 4 closes, the retainer 6 is pushed up by the spring 5, and the valve stem 41 is pushed up through the long 7.
rises and valve 4 closes. In order to adjust the clearance with the cam 1, it is necessary to install the shim 2 with an optimal thickness, which may require replacement due to wear etc. For this purpose, as shown in Fig. 5, the upper part of the valve lifter 3 A notch 9 is attached to the shim 2, through which a tool can be inserted to remove the shim 2.

Regarding the above valve lifter 3 and shim 2,
Publication No. 43202 discloses a lubrication method to prevent wear, seizure, etc. This valve lifter also has a notch for replacing the shim, and this can be used to replace the shim. It is set to work.

[Problem to be solved by the invention]

In the conventional valve lifter 3, stress is concentrated in the notch 9 during operation of the engine, resulting in cracks, or the valve lifter 3 is deformed, making it impossible to obtain a perfect circle.

This tendency is particularly noticeable in aluminum alloy valve lifters that have recently been adopted.

Further, since the size of the notch 9 is small, the workability of replacing the gym is poor and parts may be damaged during replacement.

In view of the above-mentioned problems, it is an object of the present invention to provide a means for easily replacing the shim without using the notch.

[Means for Solving the Problems] In order to achieve the above object, the present invention Q provides a cup that is interposed between a cam and a valve stem and contacts the cam via a shim to open and close the valve. In the valve lifter, the valve lifter has a two-part structure, and the first valve lifter is in the form of a disc that presses down the valve stem by the pressing force of the cam, and the first valve lifter is fitted into a valve lifter guide hole drilled in the cylinder head. A cylindrical second valve lifter that engages with the first valve lifter and moves up and down to open and close the valve; and a first valve spring and a second valve spring that support the respective valve lifters. provide.

[Function] The function during engine operation is the same as that of a valve lifter with a conventional structure, and the first valve spring plays the role of a conventional valve spring, and the second valve spring acts as an auxiliary valve lifter that supports the second valve lifter. have a role. When replacing the shim, by pushing down the second valve lifter with a jig, the jim on the first valve lifter will rise above the upper edge of the second valve lifter, and by moving the shim laterally, you can easily replace the shim. becomes.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings. 1 and 2 show the main parts of one embodiment (first embodiment) of a valve lifter according to the present invention.

In the drawings, the same parts as in FIGS. 4 and 5 are given the same numbers and detailed explanations will be omitted.

In Figures 1 and 2, 1 is a cam, 2 is a shim, and 31 is a first
a valve lifter; 32 is a second valve lifter; 4 is a valve;
41 is a valve stem, 51 is a first spring, 52 is a second spring, 6 is a retainer, and 7 is a lock (cotton pin). As shown in the figure, the conventional valve lifter 3 as shown in FIGS. 4 and 5 is divided into two parts, a first valve lifter 31 and a second valve lifter 32. The pressing force of the cam is transmitted to the valve stem 41 to directly push down the valve 4. The pressing force of the first spring 51 is transmitted to the first valve lifter 31 from the tip of the valve stem 41 to the center of the back surface of the first valve lifter 31 via the retainer 6 and the lock 7, and the cam 1 via the shim 2. During operation, it engages with cam I. When cam I is not operating and the base circle of cam 1 is above shim 2, shim 2 and cam 1 do not come into contact with each other, and a constant clearance is maintained between them.

The cylindrical second valve lifter 32 is formed with an inward flange portion 321, and a first valve lifter 32 is formed on this flange portion 321.
A valve lifter 31 is detachably attached. Further, a second spring 52 is seated on the lower surface of the flange portion 321 of the second valve lifter 32, and presses the second valve lifter 32 to the first valve lifter 31 with its pressing force. That is, the second spring 52 plays an auxiliary role to support the second valve lifter. With this configuration, the first valve lifter 31 and the second valve lifter 32 always act as one body both when the engine is stationary and when the engine is running, which is different from the conventional valve lifter 3 (Fig. 4), which is fixed as one unit. There are no holes, and it functions as a valve lifter.

When replacing the shim 2, as shown in FIG. 2, by pushing down the second valve lifter 32 in the direction shown by arrow B with a jig, the second valve lifter 32 and the first valve lifter 31 are separated, and the position of the shim 2 is changed. By making the shim 2 higher than the upper edge of the second valve lifter 32, the shim 2 can be slid in the lateral direction indicated by arrow A in the figure. At this time, naturally, the position of cam 1 is such that the base circle faces shim 2, so shim 2 easily moves laterally from the position of the valve lifter without hitting cam 1. This allows the shim 2 to be removed and the gym to be replaced easily.

FIG. 3 shows another embodiment (second embodiment) of the present invention. This embodiment differs from the previously mentioned embodiments only in the retainer 6 and lock 7 shown in FIGS. 1 and 2, and the other parts are the same, so a detailed explanation of the other parts will be omitted.

In this embodiment, a half steno with the above-mentioned retainer 6 and lock 7 is used.

41, threaded portions 411 and 311 are provided at the tip of the valve stem 41 and at the center of the lower surface of the first valve lifter 31, respectively, and the two are combined. As a result, the first valve lifter 31 and the retainer 6 are integrated, and a retainer is essentially unnecessary, simplifying the structure. In this case as well, the first valve lifter 31
The mutual relationship between the valve lifter and the second valve lifter 32 is exactly the same as in the first embodiment described above, and therefore the shim 2 can be easily replaced by the same method as described above.

As explained above, according to these embodiments, when replacing the shim 2, it is sufficient to simply push down the valve lifter, and the shim can be easily replaced. Therefore, there is no need to provide the conventional notch 9 in the valve lifter, and cracks and deformation of the valve lifter do not occur.

(Effect of the invention〕 By implementing the present invention, the following effects can be achieved.

(1) There is no need for a notch in the valve lifter, and there is no risk of cracks or deformation occurring in the valve lifter during operation.

(2) Replacement of the valve lifter is easy, has good workability, and there is no risk of damaging parts during replacement.

[Brief explanation of the drawing]

1 to 3 show embodiments of the valve lifter according to the present invention, FIG. 1 is a sectional view of the main part of the first embodiment, and FIG.
FIG. 3 is a sectional view of the main part of the second embodiment; FIGS. 4 and 5 show a valve lifter according to the prior art; FIG. 4 is a sectional view of the main part; The figure shows a perspective view of the valve lifter. DESCRIPTION OF SYMBOLS 1... Cam, 2... Shim, 3... Valve lifter, 4... Valve, 10... Cylinder head, Work 1... Valve lifter guide hole, 31... First valve lifter, 32... ...Second valve lifter, 41...Valve stem. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In a cup-shaped valve lifter that is interposed between the cam and the valve stem and contacts the cam through a shim to open and close the valve, the valve lifter has a two-part structure, and the valve stem is opened and closed by the pressing force of the cam. A first valve lifter in the shape of a disc that is pressed down, and a second valve lifter in the cylindrical shape that fits into a valve lifter guide hole drilled in the cylinder head and engages with the first valve lifter to perform vertical movement to open and close the valve. A valve lifter comprising a first valve spring and a second valve spring that are divided and supported respectively.