JP3057389B2 - Manufacturing method of engine valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an engine valve.

[0002]

2. Description of the Related Art FIG. 3 schematically shows a direct-acting type valve operating mechanism frequently used in a DOHC engine. An engine valve (01) has an intermediate portion of a shaft portion (01a) and a cylinder head (01).
It is held by being slidably fitted to a valve guide (03) press-fitted into (02).

[0003] shaft of the engine valve (01) an annular groove (04) formed in the upper end of (01a), 1 pair of cotters (05) (05) is engaged. Externally fitted to this pair of cotters (05) (05) ,
A valve spring (07) is contracted between the spring retainer (06) that is prevented from moving upward and the cylinder head (02).

[0004] Thus the engine valve (01) is biased to come on <br/> direction at all times, the valve face portion of the umbrella portion of the lower end (01b) (01c)
The port (09) is brought into close contact with the valve seat (08).
The open end of is closed.

[0005] Reference numeral (010) denotes a synthetic resin lip seal externally fitted to the upper end of the valve guide (03). The lip seal is required when its upper inner peripheral surface comes into contact with the outer peripheral surface of the shaft portion (01a). The above lubricating oil is prevented from flowing into the gap between the valve guide (03) and the shaft (01a).

[0006] (011) is that the upper surface is closed and the cylinder
Cylindrical tappet slidably fitted to the head (02)
In, in its interior, a spring retainer (06), and the engine upper portion of housing of the valve (01) and valve spring (07)
Have been. Lower surface central portion of the top wall of the tappet (011) is in abutment on the upper end of the shaft portion of the engine valve (01) (01a).

The top wall of the tappet (011) is located above
By being pressed pressure with a rotary cam (012) which, et
The engine valve (01) is driven up and down , and the port (09)
Open and close.

[0008] shaft of the engine valve (01) (01a) is, during operation of the engine is guided to the valve guide (03) and e repeat sliding movement, and the lip seal (010), the lubricant There for leaking to the port (09) and the umbrella portion (01b) is suppressed, lubrication of the shaft portion (01a) is not always satisfactory, in particular, in the exhaust valve is exposed to high temperature exhaust gases is under severe friction conditions, high wear resistance is required.

As an inexpensive surface treatment means for improving the wear resistance of the shaft portion (01a), there is a salt bath nitrocarburizing treatment (tufftriding treatment).

[0010] This is a treatment bath consisting of potassium cyanide, potassium cyanate, iron sodium cyanide, etc.
C., and the shaft (01a) is immersed in the treatment bath for a predetermined time, so that Fe, C
An oxide or a carbon / nitride compound containing elements such as r and Si is deposited to form a hardened layer.

The conventional engine valve (01) has a shaft portion (01a).
After was finishing by conventional grinding or cutting, it is produced by facilities the salt bath soft nitriding treatment on the surface thereof.

[0012]

As in the case of the above-mentioned conventional engine valve (01), the surface of the shaft portion (01a) finished by ordinary grinding or the like is only subjected to salt bath nitrocarburizing treatment. as shown in 4, the shaft portion (01a) surface roughness amplitude is relatively large of, and the surface layer portion of the shaft portion (01a), such as described above, Fe, Cr, very hard oxides such as Si Ya Sumi
The fine particles (P) made of the nitride compound remain attached.

[0013] When used in assembling such engine valves to the engine, and the inner peripheral surface of the valve guide (03), the contact surface between the shaft portion of the lip seal (010) (01a) is worn early, Further, when the hard fine particles (P) peel off and enter the valleys on the surface, the wear is further promoted.

When the valve guide (03) and the lip seal (010) are worn, the amount of lubricating oil leaking to the port (09) and the umbrella portion (01b) increases, and the leaked oil is varnished on the umbrella surface. or deposited secured to combust, or be discharged to the atmosphere together with the exhaust gas, moreover, the consumption rate of the lubricating oil is increased, lubricating oil is to be insufficient early. Also, backlash occurs in the contact portion between the shaft portion and the valve guide, or originating abnormal noise,
Gas leakage may occur.

[0015] In order to solve such a problem, either covering the inner peripheral surface of the valve guide by wear-resistant material, or the valve guide itself, with hardness rather high, to manufacture a material excellent in lubricity If it is Re, in this way, as well as essential many steps in the production, processing Ri difficult name is a new problem that the manufacturing cost is increased occurs.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to suppress the wear of the valve guide and the lip seal without taking any measures, and also to improve the lubricity. It is an object of the present invention to provide a method of manufacturing an engine valve as described above.

[0017]

In order to achieve the above object, a method of the present invention is to provide a ten-point average roughness of the surface of the shaft of an engine valve having an umbrella part connected to one end of the shaft.
After There was before processing so that the range of 1.0～10.0Myuemu, at least in part of the valve guide and the lip seal in sliding contact with the shaft portion to form a hardened layer by performing salt bath nitrocarburizing treatment and then curing this By applying super finish polishing to the surface of the layer, a hill-shaped contact surface with extremely low roughness can be obtained.
It is characterized by alternately forming a valley-shaped oil holding surface lower than that .

[0018]

[Action] The shaft is pre-processed to a surface roughness of 1.0 to 10.0 μm .
After the hardened layer is formed by applying a salt bath nitrocarburizing treatment, and facilities the superfinishing grinding processed into cured layer of this, the surface of the cured layer, a very small hill-like contact surface roughness, trough-like By alternately forming the oil retaining surface , the hill-shaped contact surface comes into surface contact with the valve guide and the lip seal to reduce the surface pressure, and the valley-shaped oil retaining surface serves as an oil reservoir. was acting
Because, wear of the valve guide and the lip seals are effectively <br/> suppressed.

[0019]

An embodiment of the present invention will be described below with reference to the drawings. Of (A) ~ FIG. 1 (C) shows a method of the present invention in order of steps, first (A), the various engine valves finished each part to a predetermined size by machining (1)
The shaft portion (1a) excluding the shaft end portion and the umbrella portion is sandwiched between a grinding wheel (2) and an adjusting wheel (3) in a centerless grinding machine, for example.
(1a) is the ten-point average roughness (Rz) of the surface at any point
However , adjust the grinding wheel (2) so that it is in the range of 1.0 to 10.0 μm.
Grinding me.

[0020] Then, (B), the shaft portion (1a) whole <br/>, umbrella portion excluding head front of (1d) across (1c), potassium cyanide, potassium cyanate, sodium reduction of iron cyanide by immersing a predetermined time from the consisting treatment bath (not shown) etc., subjected to salt bath soft nitriding treatment, on the surface, the hardened layer having a thickness of about 10~20μm
Form (4).

[0021] Finally, except for (C), the hardened layer axial end portion of the first from the annular groove (1b) in (4) shaft portion is formed (1a), and the umbrella portion (1c) The part is super-finished by, for example, a grinding wheel (5) of a super-finishing board. The polishing allowance at this time is preferably about 1.0 μm.

[0022] The engine valve (1) in such a process ultra
When finished , as shown in FIG. 2, the surface of the shaft portion (1a) has a ridge portion of the surface roughness of the hardened layer (4) , and hard fine particles adhering to the surface are removed. The skewness of the amplitude distribution curve of the surface roughness becomes negative, and the hill-shaped micro contact surface (6) with extremely small roughness and the valley-shaped oil holding surface (7) having a lower roughness are alternately formed. You.

[0023] the contact surface (6), compared valve guide and the lip seals (both not shown), together with the close sliding contact with contact substantially plane, and the effect of lowering the surface pressure, also the oil holding surface (7) acts as an oil reservoir to enhance the oil retention of the lubricating oil. Therefore, abrasion of the valve guide and the lip seals rather very small oil drops by wear of anti
It is .

In the above embodiment, the surface roughness (Rz) of the shaft portion (1a) before the salt bath nitrocarburizing treatment is set in the range of 1.0 to 10.0 μm. Later, it is difficult to form a sufficiently deep oil retaining surface (7), and if it is coarser than 10.0 μm, a sufficiently long contact surface (6)
This is because it is difficult to secure the abrasion resistance of the valve guide and the lip seal.

The reason why the super-finishing is not performed in the vicinity of the annular groove (1b) is that a cotter (not shown) fitted in the annular groove (1b) is formed by giving an appropriate roughness to the portion. a order to the slip <br/> prevented.

[0026]

According to the present invention, the surface of the shaft portion, Runode to form a very small hill-like contact surface and the valley-like oil holding surface roughness, measures any way to the valve guide and the lip seal Even without it , they can minimize their wear,
In addition, the sliding surfaces of each other can be appropriately lubricated.

[Brief description of the drawings]

FIG. 1 schematically shows the method of the present invention in the order of steps, wherein (A)
Is a plan view when the surface of the shaft portion is processed to a predetermined surface roughness by a centerless grinding machine, and (B) is an enlarged half section in a state where salt bath nitrocarburizing treatment is applied to all surfaces except an umbrella table FIG. 7C is an enlarged half-sectional view when superfinishing is performed on the shaft portion excluding the vicinity of the annular groove portion and the umbrella portion.

FIG. 2 is an enlarged sectional view of a surface roughness of a portion A in FIG. 1 (C).

[Figure 3] and direct acting type valve operating mechanism is a longitudinal sectional front view of a main part of a conventional engine valve assembled thereto.

FIG. 4 is an enlarged sectional view of a surface roughness of a shaft portion of an engine valve manufactured by a conventional method.

[Explanation of symbols]

 (1) Engine valve (1a) Shaft (1b) Annular groove (1c) Head (1d) Head (2) Grinding wheel (3) Adjustment wheel (4) Hardened layer (5) Wheel (6) Contact surface (7) Oil holding surface

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masanori Kanda 2958 Ishikawa, Fujisawa-shi, Kanagawa Prefecture Fujisawa Plant Fujisawa Plant (56) References JP-A-60-47809 (JP, A) JP-A-55- 32969 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) F01L 3/02

Claims (1)

(57) [Claims] The surface of the shaft portion of an engine valve having an umbrella portion connected to one end of the shaft portion has a ten-point average roughness of 1.0.
After pre-processed to be in the range of ～10.0Myuemu, at least in part of the valve guide and the lip seal in sliding contact with the shaft portion to form a hardened layer by performing salt bath nitrocarburizing treatment, then the cured layer of this by performing superfinishing grinding machining on the surface, the very small hill-like contact surface roughness, it
A method for manufacturing an engine valve, comprising alternately forming a valley-shaped oil holding surface having a lower height .