JPS62291409A - Ceramic valve retaining structure - Google Patents

Abstract

PURPOSE:To prevent the breakage of a stem of a valve due to a concentrated load which stem is supported through a cotter to a retainer, by forming an escape portion at a lower end of the retainer to provide a non-contact condition of the retainer to a lower end of the cotter. CONSTITUTION:A valve 1 consists of a valve member 1a and a stem 1b, and a cotter 3 is fitted to the stem 1b. Further, a retainer 4 is mounted on the outer peripheral surface of the cotter 3. The retainer 4 is formed at its lowermost end on the inner periphery with a chamfer 4c rounded arcuately over the circumference thereof. The chamfer 4c serves as an escape portion located at a lower outer peripheral portion of the cotter 3 under the non-contact condition. Accordingly, the lower end of the cotter 3 is prevented from being locally pressed by the lower end of the retainer 4, and a contact force of the retainer 4 to the cotter 3 is dispersed on the entire surface of the cotter 3, thereby preventing a concentrated load from being applied from the cotter 3 to the stem 1b.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a mechanism for supporting intake and exhaust valves made of ceramic through cotters, and particularly relates to an improvement in this mechanism. Regarding the valve holding structure.

[Prior Art] In recent years, intake and exhaust valves for the combustion chamber of an engine have been proposed to be made of heat-resistant ceramic. In this case, the stem S of the valve b is supported by a retainer r via an external type vine C, as shown in FIG. At this time, the length of the retainer C and the retainer r are set to be approximately the same, and the retainer C
A taper is formed on the outer circumferential surface of the retainer C and on the inner circumferential surface of the retainer r, respectively, and the wedge effect of these tapers causes the cotter C and the retainer r to be in close contact with each other.

[Problem to be Solved by the Invention 1] However, with the operation of valve b, the tipper C comes to more firmly abut against the stem S due to the above-mentioned wedge effect;
This wedge effect is greatest at the lower end n of the retainer r.

As a result, the lower end n of the retainer R acts firmly on the stem S via the lower end m of the holder C. therefore,
There is an inconvenience that a concentrated load is generated on the stem S by the lower end m of the clasp C, which may cause cracks k to occur in the stem S and cause damage.

This invention was made to solve these problems, and even though the valve is made of ceramic and is supported by a member such as a cotter, concentrated loads can be avoided and the life of the valve can be extended. It is an object of the present invention to provide an excellent ceramic valve holding mechanism that has such valuable effects, has an extremely simple structure without becoming complicated, and is advantageous in terms of cost.

[Means for Solving the Problems] The present invention provides a system in which a stem of a ceramic valve for intake or exhaust air in an engine combustion chamber is supported by a wedge action in a mounting hole of a retainer via a cotter, in which the lower end of the retainer is The footer adopts a configuration characterized in that a relief portion is formed at the lower end of the footer so as to be in a non-contact state.

[Operations and Effects] According to the present invention configured as described above, the lower end of the spigot does not come into intensive contact with the stem of the valve, and the inner circumferential surface of the cotter comes into contact with the outer circumferential surface of the stem approximately evenly. Since the valves come into contact with each other, load concentration is avoided, and cracks do not occur in the valve, contributing to longer life. Moreover, in order to realize this, it is only necessary to provide a relief part at the lower end of the retainer that does not come into contact with the retainer, resulting in a simple structure and being advantageous in terms of cost.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

First, in the first embodiment shown in FIG. 1, reference numeral 1 denotes an exhaust valve for an engine combustion chamber, which will be described later. This valve 1 is made of ceramic and consists of a valve body 1a and a cylindrical stem 1b. There is.

A stem 1b of this valve 1 is formed with an annular groove 2 located at its upper end. 3 is a metal kotsuta, which, as can be seen in Figure 2, has a two-part outer shell and an overall cylindrical shape. Such a tipper 3 is attached to the stem 1b of the valve 1, and a protrusion 3a having a semicircular cross section and located within the groove 2 is integrally formed on the inner peripheral surface along the circumferential direction. Reference numeral 4 denotes a retainer fitted to the outer circumferential surface of the cotter 3, which consists of an annular portion 4a and a flange portion 4b, each having a mounting hole inside. A taper in the direction is formed.

In this case, the vertical length dimensions of the retainer 4 and the cotter 3 are set to be approximately the same, and the lowermost end of the inner circumferential side of the retainer 4 is provided with an arc-shaped roundness throughout the circumferential direction. A chamfered portion 4C is formed. This recessed portion 4C acts as a relief portion and is positioned in such a manner that it does not come into contact with the outer peripheral surface of the lower end of the cotter 3.

The valve 1 having such a structure is attached to the cylinder head 5 of an engine as shown in FIG. A valve spring 6 is provided between the valve 1 and the cylinder head 5. The spring 6 urges the valve 1 upward in the axial direction, and the valve body 1a seals the intake passage 8 through the valve seat 7. It is open to the public. At this time, depending on the state of the biasing state of the valve spring 6 in the above-mentioned direction, the taper of the retainer 4 causes the stopper 3 to firmly abut against the outer circumferential surface of the stem 1b with a so-called wedge effect.

When the engine is in operation, the pallet 11 is axially displaced up and down to repeatedly engage and disengage the valve body 1a from the valve sea door, thereby alternately closing the exhaust passage 8 rWU. Due to such vertical displacement of the valve 1, the valve 3
However, in this embodiment, a chamfered portion 4C is provided at the lower end of the retainer 4, so that the lower end of the retainer 4 contacts the stem 1b firmly due to the wedge effect with the retainer 4.
The lower end of the retainer 3 is no longer pressed locally, and the contact force from the retainer 3 is spread over the entire surface of the retainer 3, so that only the lower end of the retainer 3 is firmly and locally bitten into the stem 1b. disappears. As a result, concentrated load is not applied to the stem 1b of the valve 1 due to the lower end of the handle 3, and the stem 1bf: does not crack or break, which extends the usable period and contributes to longer life. It is what it is.

Although the above-mentioned stem 1b has a significant effect,
In order to prevent cracks, etc., it is sufficient to form a relief part such as a chamfered part 4C on the retainer 4, so a slight change is sufficient and the overall 1M structure does not increase in size and remains a simple structure. This method is advantageous from an industrial standpoint as well as being inexpensive.

Here, a supplementary explanation will be given schematically regarding the structure of an engine to which the ceramic valve 1 is applied.

9 is a tubular valve guide inserted through the stem 1b of the valve 1; 10 is a cam connected to the shaft 11; 12 is a swing arm against which the cam 10 contacts from above; one end of this swing arm contacts the upper end of the stem 1b; The end is supported by a spherical fulcrum 13. 14 is an intake valve, which has the ability to open and close the intake passage 15 via a valve seat 16;
It is configured similarly to the intake valve 1. 17 is a valve guide, 18 is a valve spring, and one is a swing arm, one end of which abuts the upper end of the valve 14 and the other end supported by a spherical fulcrum 20.

A cam 21 is connected to the shaft 22, and is in contact with the swing arm 19. 23 is a cylinder block, and 24 is a piston for moving up and down within the cylinder block 23.

Next, a second embodiment of the present invention will be described with reference to FIG.

In the first embodiment, the chamfered part 4C was formed as a relief part, but in this first embodiment, a cutout part 4 different from the chamfered part 4C is formed.
d is formed as a relief part.

With this configuration, the same effects as in the first embodiment can be obtained. In the second embodiment, the same parts as in the first embodiment are marked with the same symbol, and only the different parts are explained.

Next, FIGS. 6 and 7 show the third and fourth parts of this invention.
An example is shown. In the third embodiment, the lower end of the cotter 3 is
It is set longer than in the embodiment, and its lower end extends downward longer than that of the retainer 4. Further, in the fourth embodiment, the lower end of the holder 3 is set longer than in the first embodiment and is configured to extend further downward than the lower end of the retainer 4, as described above. With such a configuration, the same effects as in the first embodiment can be obtained.

In the third and fourth embodiments, the same parts as those in the first embodiment are given the same reference numerals, and only the different parts will be explained.

In each of the embodiments described above, the protruding portion of the retainer is formed to have a semicircular cross section, but it is not limited to this shape and may be formed, for example, in a rectangular shape. In this case, it goes without saying that the full cross-sectional shape of the valve stem also corresponds to the protrusion.

In addition, various changes may be made without departing from the gist of the present invention in concrete and practical implementation.

[Brief explanation of the drawing]

1 to 4 show a first embodiment of the present invention.
2 is a longitudinal cross-sectional view of the cotter, FIG. 3 is a cross-sectional view of the retainer, FIG. 4 is a longitudinal cross-sectional view of the engine as applied to the engine, and FIGS. FIG. 8 is a sectional view of a main part showing the second and fourth embodiments, respectively, and a diagram showing a conventional cotter. In the diagram 1...Ceramic valve 1b...Stem 1
a... Valve body 2... Full 3... Kotta 3a...
・Protrusion portion 4...Retainer 8...Exhaust path 15...
・Intake path 4C...Relief part (relief part) 4d...
Notch (recess)

Claims (1)

[Scope of Claims] 1) A stem of a ceramic valve that performs intake or exhaust air in an engine combustion chamber is supported by a wedge action in a mounting hole of a retainer via a cotter, wherein a lower end of the retainer is provided with a stem of the cotter. A ceramic valve holding structure characterized by having a non-contact relief part formed at the lower end. 2) The ceramic valve holding structure according to claim 1, wherein the relief portion of the retainer is formed of a chamfered portion having an arcuate roundness. 3) The ceramic valve holding structure according to claim 1, wherein the relief portion of the retainer is a notch.