JP2527814Y2 - Tappet with inner shim and outer shim - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tappet used for a direct-acting type valve operating mechanism, and more particularly to a tappet having an inner shim and an outer shim for adjusting a valve clearance.

[0002]

2. Description of the Related Art FIG. 3 schematically shows a direct-acting type valve operating mechanism frequently used in a DOHC type engine. An engine valve (01) includes a pair of cotters (02) and (02) and a spring. Cylinder head by retainer (03), valve spring (04), etc.
(05).

[0003] At the upper end of the engine valve (01), a tappet (06) having a cylindrical iron tappet body (06a) whose upper surface is closed is attached to the lower surface of the circular upper wall (07). The valve (01) is fitted from above so as to contact the stem end of the valve (01).

An annular side wall (08) connected to the upper part of the upper wall (07)
Inside, a circular recess (09) is formed, and this recess (09)
Is fitted with a shim (010) for preparing a valve clearance.

The engine valve (01) has a cylinder head (0)
The entire tappet (06) guided by 5) is opened and closed by being pushed by the rotating cam (011) brought into contact with the upper surface of the shim (010).

[0006]

In order to adjust the valve clearance in such a direct acting type valve operating mechanism,
Prepare multiple types of shims (010) with different thicknesses, select the required thickness of the shim (010) according to the distance between each tapet (06) and the rotating cam (011), and install it. I am trying to do it.

In this case, since the valve clearance needs to be adjusted with an accuracy of, for example, 0.02 to 0.05 mm, various types of shims (010) having different thicknesses must be prepared.

That is, the tappet (06) and the rotating cam (011)
Assuming that the amount by which the interval changes is “T” and the unit amount of valve clearance adjustment is “t”, the required number “N” of types of shims (010) can be obtained by the following equation. N = T / t + 1

For example, the amount "T" at which the interval changes is 1.6 m.
If the adjustment unit amount “t” is 0.05 mm in the case of m,
The number of types “N” of the thickness of the shim (010) is 33 types. "T" to adjust valve clearance with higher accuracy
Is 0.02 mm, there are 81 types of "N".

Preparing such a large number of shims (010) makes inventory management complicated, increases dead stock, is uneconomical, and requires an individual tape (0).
For each 6), it is necessary to select a shim (010) having an appropriate thickness from many types in accordance with the distance from the rotating cam (011), and thus there are many disadvantages in work management.

SUMMARY OF THE INVENTION It is an object of the present invention to improve these disadvantages and to provide a tapet in which the valve clearance can be adjusted to a required accuracy by using fewer kinds of shims.

[0012]

In order to achieve the above-mentioned object, the present invention provides a tappet in which an outer shim is fitted into a recess formed at the upper end of a cylindrical tappet body having a closed upper surface. An inner shim was sandwiched between the lower surface of the upper wall of the main body and the stem end of the engine valve, and the thickness of the inner shim and the outer shim in the axial direction was varied at a relatively coarse first pitch. A plurality of types are provided, and the other is selected and mounted from among a plurality of types of inner shims and outer shims as a plurality of types obtained by subdividing the first pitch at a second pitch obtained by subdividing the first pitch. By doing
In this configuration, the valve clearance is adjusted.

It is desirable that the thickness of the inner shim be different at the first pitch and the thickness of the outer shim be different at the second pitch.

[0014]

A coarse adjustment is performed by selecting and mounting one type from a shim group whose thickness changes at a first pitch that is relatively coarse, and further, a second adjustment is performed by subdividing the first pitch with a thickness. If fine adjustment is performed by selecting and mounting one type from a group of shims that change with the pitch, the valve clearance can be adjusted using the second pitch as an adjustment unit, and a single shim can be adjusted. The number of types of shims can be greatly reduced as compared with the case where the thickness is changed.

The fine adjustment with the outer shim (12), which is easier to replace than the inner shim (11), facilitates the adjustment operation.

[0016]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention, which is substantially the same as the conventional valve train shown in FIG. That is, an engine valve (1), a pair of cotters
(2) (2), spring retainer (3), valve spring
(4) The cylinder head (5) and the upper rotating cam (10)
This is the same as the conventional example of FIG.

The tappet (6) is also similar to the conventional example shown in FIG.
It has a cylindrical tappet body (6a) having a closed upper surface, and a circular recess () is formed inside an annular side wall (8) connected to the upper part of the circular upper wall (7). 9) is formed.

A first shim (12) is fitted in the recess (9), and further, a gap between the stem end of the engine valve (1) and the upper wall (7) of the tappet body (6a). Is mounted with a second shim (11) interposed therebetween. Hereinafter, the first shim (12) attached to the recess (9) is referred to as "outer shim"
The second shim sandwiched between the stem end of (1) and the upper wall (7)
(11) is referred to as “inner shim”.

[0019] Inner shim (11) and outer shim (12)
Are prepared in a plurality of types each having a different thickness in the axial direction. However, one of the shims has a thickness changed corresponding to a dimension obtained by dividing a required adjustment range of the valve clearance by a relatively coarse pitch (hereinafter, referred to as a first pitch), and the other has a The thickness is changed according to the size obtained by subdividing the first pitch by the second pitch corresponding to a desired adjustment unit amount.

From the two groups of inner shim (11) and outer shim (12) having different thicknesses, one is set according to the distance between each tappet (6) and the rotary cam (10). By selecting and mounting a seed, coarse adjustment is performed by a shim whose thickness changes at the first pitch, and fine adjustment is performed by a shim that changes at the second pitch to adjust the valve clearance as required. Can be. In this case, it is desirable that the first pitch be a value obtained by equally dividing the amount of the range in which the interval between the tappet (6) and the rotating cam (10) changes by an integer value.

Hereinafter, specific numerical values will be described by way of example.
In this case, the thickness (T ₁ ) of the inner shim (11) is changed at a first pitch, and the thickness (T ₂ ) of the outer shim (12) is changed at a second pitch.

To facilitate comparison with the conventional example in which the thickness of a single shim is changed, the tappet (6)
The amount "T" at which the distance between the rotating cam (10) and the rotating cam (10) changes is 1.6 mm,
The case where the adjustment unit amount “t” of the valve clearance is 0.05 mm will be described.

Assuming that the first pitch at which the thickness of the inner shim (11) changes is 0.4 mm obtained by dividing the interval change amount "T" into four, the inner shim (11) and the outer shim (12) are as follows. ,
What is necessary is just to prepare the thing of the following thickness, respectively.

The thickness of the inner shim (11) for coarse adjustment
By changing (T ₁ ) with a pitch of 0.4mm, the inner shim
(11) is of the following five types. _{(11 1) T 1 = Ta} (11 2) T 1 = Ta + 0.4mm (11 3) T 1 = Ta + 0.8mm (11 4) T 1 = Ta + 1.2mm (11 5) T 1 = Ta + 1.6mm where , Ta are reference thicknesses of the inner shim (11).

Outer shim (12) thickness for fine adjustment
If (T ₂ ) is changed at a pitch of 0.05 mm, the outer shim (12) has the following eight types. _{(12 1) T 2 = Tb} (12 2) T 2 = Tb + 0.05mm (12 3) T 2 = Tb + 0.1 mm (12 4) T 2 = Tb + 0.15mm (12 5) T 2 = Tb + 0.2 mm (12 ₆ ) T ₂ = Tb + 0.25 mm (12 ₇ ) T ₂ = Tb + 0.3 mm (12 ₈ ) T ₂ = Tb + 0.35 mm where Tb is the reference thickness of the outer shim (12).

The five types of inner shims (11) and (8)
By selecting and mounting one of each type of outer shim (12), the valve can be set according to the distance between the tapet (6) and the rotating cam (10), which changes in the range of 1.6 mm. The clearance can be adjusted to a predetermined amount.

When the tapet (6) and the rotary cam (10) are arranged closest to each other, that is, when the amount of change "T" in the interval between the two is 0 mm, the reference thickness (Ta) By selectively mounting the inner shim (11) and the outer shim (12) having the reference thickness (Tb), the valve clearance can be adjusted to a predetermined amount.

Here, when the distance between the tappet (6) and the rotary cam (10) is enlarged and the distance variation "T" is increased to 0.85 mm, the inner shim (11) is set to T _1. = Ta + 0.
8mm (11 ₃ ) is selected, and as the outer shim (12), T ₂ =
If (12 ₂ ) of Tb + 0.05 mm is selected and installed, the added value of the increase in the thickness of the two shims will be 0.85 mm, which corresponds to the increase of “T”, and the valve clearance will be the same as above. Can be adjusted to a predetermined amount.

[0029] When the distance change amount "T" is increased to a maximum of 1.6mm as inner shim _{(11), T 1 = Ta} + 1.
6mm (11 ₅ ) is selected, and as the outer shim (12), T ₂ =
What is necessary is just to select (12 ₁ ) of Tb.

By selecting and combining one of the five types of inner shim (11) and eight types of outer shim (12), the interval variation “T” is in the range of 0 mm to 1.6 mm. Can be adjusted in units of 0.05 mm.

In the case of adjusting with a single shim (010) shown in FIG. 3, it is necessary to prepare 33 types of shims whose thickness is changed at a pitch of 0.05 mm. In the case of FIG. 1 in which the adjustment is made at the two locations of (11) and the outer shim (12), it is sufficient to prepare 13 types of shims in total, which can greatly reduce the number of types of parts. it can.

When the valve clearance is more finely adjusted, the rate of reduction in the number of types of parts is further increased. For example, when adjusting the valve clearance with a pitch of 0.02 mm, in order to adjust with a single shim (010), it is necessary to prepare 81 types of shims as described above. As Sim (11)
It is sufficient to prepare a total of 25 types as the outer shim (12) as 20 types with the thickness changed with the 0.02 mm pitch, as five types with the thickness changed with the same 0.4 mm pitch as described above.

In the above embodiment, the thickness of the inner shim (11)
(T ₁ ) is changed by a relatively coarse first pitch, and the thickness (T ₂ ) of the outer shim (12) is changed by a second pitch obtained by subdividing the first pitch. Outer Shim (12)
May be changed at a first pitch, and the inner shim (11) may be changed at a second pitch. However, when adjusting the valve clearance in actual work, usually, the coarse adjustment for selecting the shim that changes with the first pitch is first performed, and then the second adjustment is performed.
The thickness (T ₂ ) of the outer shim (12), which is easier to replace, is set to the second value because of the configuration of the tapet (6) because the shim that changes with the pitch is selected for fine adjustment. It is practically advantageous to change the pitch.

FIG. 2 shows a second embodiment of the present invention. The same constituent members as those of the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the second embodiment, the upper wall of the tappet body (6a)
A cylindrical downward convex part (7a) is connected to the center of the lower surface of (7), and a bottomed cylindrical inner shim (11) whose lower end is closed is fitted to the lower end part of this convex part (7a). Have been combined. With the configuration as in the second embodiment, the lower end of the projection (7a) is
By being covered by (11), wear of the projections is prevented, which is particularly significant when the tappet body (6a) is made of a light alloy such as aluminum having low wear resistance. The inner shim (11) may be simply fitted to the projection (7a), but it is more preferable to press fit or fix or prevent the inner shim with an adhesive or other means.

[0035]

[Effects of the Invention] (a) The thickness of the shim can be greatly reduced as compared with the case where the valve clearance is adjusted by a single shim. , Inventory management becomes easier.

(B) Since only a few types of shims are required, dead stock is reduced and the system is economical.

(C) The configuration of the tapet and peripheral members can be implemented without major changes.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a conventional tapet provided with a single shim.

[Explanation of symbols]

(1) Engine valve (2) Cotta (3) Spring retainer (4) Valve spring (5) Cylinder head (6) Tappet (6a) Tappet body (7) Upper wall (7a) Convex part (8) Side wall (9) Recess (10) Rotating cam (11) Inner shim (12) Outer shim

Claims (2)

(57) [Scope of request for utility model registration] An outer shim is fitted into a recess formed at an upper end of a cylindrical tappet body having a closed upper surface, and an inner shim is provided between a lower surface of an upper wall of the tappet body and a stem end of an engine valve. With the shim interposed, the inner shim and the outer shim have different thicknesses in the axial direction, one of which is different at a relatively coarse first pitch, and the other is a second type obtained by subdividing the first pitch. By selecting and installing one of each of the inner shim and outer shim as a plurality of different types at different pitches,
A tappet having an inner shim and an outer shim for adjusting a valve clearance. 2. The outer shim and the inner shim according to claim 1, wherein the thickness of the inner shim is made different at the first pitch and the thickness of the outer shim is made different at the second pitch. Tappet to prepare.