JPH0821215A - Engine valve - Google Patents

Abstract

PURPOSE:To provide an engine valve wherein a valve shaft part having high hardness, and excellent in abrasion resistance can be formed without discharging drain to be subjected to the regulation of the environment, and the processing cost is low. CONSTITUTION:Hardened parts 6 formed by hardening processing are provided within an upper slid-contact range 5b with which the upper end of a valve guide is brought in slide-contact, and within a lower slide-contact range 5a with which the lower end of the valve guide is brought in slide-contact with out of a slide-contact range 5 with which the valve guide of the outer peripheral surface part 2A of a valve shaft 2 of an engine valve made of mamartensite heat resistant steel, and the outer peripheral surface part 2A is formed by finish processing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine valve used as an intake valve or an exhaust valve in an internal combustion engine.

[0002]

2. Description of the Related Art Generally, as an intake / exhaust valve of an internal combustion engine, a mushroom-shaped engine valve in which a valve shaft is connected to a valve shaft is used. Conventionally, heat-resistant steel is generally used as a material for the valve shaft part. In order to impart wear resistance, a salt bath soft nitriding treatment (tufftride treatment) is performed to increase the hardness. However, since this salt bath nitrocarburizing treatment is a treatment in which it is immersed in a treatment bath consisting of potassium cyanide, potassium cyanate, sodium iron cyanide, etc., its treated wastewater is subject to pollution control, and there is limited wastewater treatment equipment. It could only be done in place.

Further, fine particles made of hard oxides containing iron, chromium and silicon, and carbon / nitride compounds adhere to the surface layer portion subjected to the salt bath soft nitriding treatment, which causes early wear of valve guides and the like. As an improvement of the invention, Japanese Patent Laid-Open No.
A method for manufacturing an engine valve disclosed in Japanese Patent No. 1412112 has been proposed. In this method, it is necessary to perform pre-processing to a predetermined surface roughness before the salt bath nitrocarburizing treatment and to perform super-finishing after the treatment. Therefore, it has a drawback that the processing cost is high.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art by providing a valve shaft portion having high hardness and excellent wear resistance without discharging wastewater which is subject to pollution control. It is intended to provide an engine valve that can be formed and can be processed at low cost.

[0005]

According to the engine valve of the present invention, the upper end of the valve guide is slidable in the sliding contact range of the outer peripheral surface of the valve shaft of the engine valve made of heat-resistant martensitic steel. The upper sliding contact area that touches,
A hardened part by quenching (surface quenching) is provided in the lower sliding contact area where the lower end of the valve guide is in sliding contact, and the outer peripheral surface is finished.

As a quenching treatment method for forming a hardened portion in the present invention, induction hardening, flame quenching by a burner, irradiation of high density energy such as TIG arc, laser, electron beam and the like is used. Although various quenching treatment methods such as quenching (surface quenching) can be used, quenching treatment by laser irradiation is particularly preferable because a hardened portion can be accurately formed in a predetermined quenching range. In order to increase the quenching hardness during the quenching treatment, a cooling medium such as nitrogen gas, carbon dioxide gas or water may be sprayed on the material to be treated after being heated to a high temperature. The hardness of the hardened part is preferably 600 or more in terms of Vickers hardness by rapid cooling by these cooling media or self-cooling ability, and if it is less than 600, the abrasion resistance is insufficient.

If the depth of the hardened portion by the quenching treatment in the present invention is less than 0.1 mm, the hardened layer is too thin and wear resistance is insufficient, and if it exceeds 1.0 mm, the brittleness of the hardened layer increases. It is preferable that the thickness is 0.1 to 1.0 mm because cracks are likely to occur on the surface during sliding friction and cutting of the valve shaft is likely to occur.

Regarding the surface roughness of the finish machining of the outer peripheral surface of the valve shaft in the present invention, the ten-point average roughness of less than 0.1 .mu.mRz is expensive to process, and if it exceeds 5.0 .mu.mRz, the valve guide and the oil seal are inferior. It is preferable to set the thickness to 0.1 to 5.0 μmRz, because the wear of the lip lip easily progresses.

[0009]

In the engine valve of the present invention, when the valve shaft portion is inserted into the valve guide and incorporated in the engine, the valve shaft is hardened by quenching treatment provided in the upper sliding contact range and the lower sliding contact range of the outer peripheral surface of the valve shaft. The portion is in sliding contact with the valve guide to prevent wear of the valve shaft, and the outer peripheral surface portion is finished so that rapid wear of the valve guide is not caused.

Since the hardening portion by the quenching treatment only needs to be provided in the upper sliding contact area and the lower sliding contact area near the upper and lower end portions of the valve shaft, the quenching processing time is short and the processing cost is low.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In FIGS. 1 and 2, reference numeral 1 denotes a valve body of an intake valve, which has a mushroom shape in which a valve umbrella 3 is integrally connected to one end of a valve shaft 2 and is made of martensitic heat-resistant steel (eg JIS SUH1).
1) Made. On the outer peripheral surface 2A of the valve shaft 2, the valve guide 12 is reciprocally opened and closed while being assembled in the engine.
Of the sliding contact range 5 (see below) slidingly contacting (see FIGS. 3 and 4), the upper sliding contact range 5b in which the upper end 12b of the valve guide 12 is in sliding contact and the lower sliding contact in which the lower end 12a of the valve guide 12 is in sliding contact. A hardened portion 6 is provided in a range 5a (all of which will be described later) by quenching (surface quenching) by laser irradiation. FIG. 2 shows that the outer peripheral surface portion 2A is developed into a flat shape and the valve shaft 2
5 is a cross-sectional view taken perpendicularly to the axial direction of FIG. 1, in which a hardened portion 6 having a depth H is formed over the entire outer peripheral surface portion 2A of the upper sliding contact area 5b and the lower sliding contact area 5a.

The hardening portion 6 is formed by a general laser processing apparatus (not shown) of a type in which the laser light output from the laser oscillator is redirected by a reflecting mirror and is condensed by a condenser lens. To collect the laser light on the outer peripheral surface portion 2A of the valve shaft 2 to rotate the valve shaft 2 around the central axis at a constant speed and move it in the axial direction, so that the desired range of the valve shaft 2 can be adjusted. The heating part was heated to about 1000 ° C., and then the heating part was rapidly cooled by spraying nitrogen gas. A desired heating width for each rotation of the valve shaft is obtained by adjusting the position of the defocusing method in which the outer peripheral surface portion 2A is moved closer to or further from the focus position formed by the focusing of the focusing lens. Further, the desired depth H can be obtained by adjusting the output of the laser oscillator. In this embodiment, for the valve shaft 2 having a diameter of 6 mm, the hardening portion 6 (having a depth H = 400 μm). Vickers hardness = 600 or more) was formed.

FIGS. 3 and 4 show a state in which the valve body 1 is incorporated in a cylinder block 11 of an engine. In FIG. 3, reference numeral 12 is a metal valve guide fixed to the cylinder block 11. The valve shaft 2 of No. 1 is fitted with a small clearance. 13 is an oil seal attached to the upper end of the valve guide 12 by a ring 13a, 13
b is the oil seal lip, which is the outer peripheral surface portion 2A of the valve shaft 2.
Slide on. Reference numeral 15 is an intake passage, 16 is a valve seat on which the valve umbrella 3 is seated, 17 is a retainer fitted to the shaft head 4 of the valve body 1 by a cotter 18, and 19 is a valve spring. In these figures, the hardening portion 6 of the valve shaft 2 is not shown.

FIG. 3 shows the valve fully closed state in which the valve face surface portion of the valve umbrella 3 is seated on the valve sheet 16, and FIG. 4 shows that the shaft head 4 portion is pushed down by a cam shaft (not shown) so that the valve body 1 is closed. Shows the state where the valve reaches the lower end position and is fully opened. Then, from the position a on the valve shaft 2 corresponding to the lower end surface of the valve guide 12 in FIG. 3 (valve fully closed state) to the valve shaft 2 corresponding to the upper end surface of the valve guide 12 in FIG. 4 (valve fully open state). The range up to the position b is the sliding contact range 5 that is in sliding contact with the valve guide 12 of the valve shaft 2. In this sliding contact range 5, a range from a position c on the valve shaft 2 near the end of the valve shaft 2 by a predetermined distance Q (1 mm in this embodiment) from the lower end surface of the valve guide 12 in FIG. 4 to the position a. Is the lower sliding contact range 5a, and the range from the position d on the valve shaft 2 closer to the valve umbrella to the position b by a predetermined distance R (1 mm in this embodiment) from the upper end surface of the valve guide 12 in FIG. In the upper sliding contact range 5b, the hardening portion 6 may be provided at least over the upper sliding contact range 5b and the lower sliding contact range 5a as in this embodiment.

In FIG. 4 (valve fully open state), the upper sliding contact range 7 from the position e on the valve shaft 2 corresponding to the oil seal lip 13b to the position d (that is, the valve shaft 2 is the valve guide 12 and the oil seal lip). If the hardening part 6 is provided over the upper sliding contact range in which it slidably contacts 13b,
It is preferable because abrasion of the outer peripheral surface portion 2A due to the sliding contact of the oil seal lip 13b is surely prevented. Then, after the hardened portion 6 is formed with high precision (without excess or deficiency of the forming range) over the upper sliding contact range 5b and the lower sliding contact range 5a by the quenching process by the above-mentioned laser processing apparatus, the outer peripheral surface part 2A of the valve shaft 2 is formed. Has a surface roughness of approx.
Z is finished over the entire length of the valve shaft 2 part. The finishing process may be performed at least in the range from the position a to the position e.

When the valve body 1 is used by inserting the valve shaft 2 into the valve guide 12, the melt hardening portion 6 provided in the upper sliding contact area 5b and the lower sliding contact area 5a of the outer peripheral surface 2A.
However, regardless of the vertical movement of the valve body 1, the outer peripheral surface portion 2A is always in sliding contact with the inner peripheral surfaces of the upper end portion 12b and the lower end portion 12a of the valve guide 12, and the outer peripheral surface portion 2A is finished.
And the wear of the inner peripheral surface of the valve guide 12 are both suppressed to a small amount.

The present invention is not limited to the above-described embodiment. For example, the hardened portion 6 is a range obtained by adding an appropriate margin distance to the lower sliding contact range 5a, the upper sliding contact range 5b or the upper sliding contact range 7. You may provide over.

[0018]

As described above, according to the present invention,
Since the hardened part by quenching treatment is provided in the upper sliding contact area and the lower sliding contact area of the outer peripheral surface of the valve shaft, and the outer peripheral surface is finished, drainage that is subject to pollution control as in salt bath nitrocarburizing. It is possible to form a valve shaft part with excellent wear resistance without discharging, and the hardening part can be formed within a small range of the entire length of the valve shaft. Also, the processing cost is low because it only needs to be done once after quenching.

[Brief description of drawings]

FIG. 1 is a front view of an engine valve showing an embodiment of the first invention.

FIG. 2 is a cross-sectional view of a melt hardening portion of a valve shaft of the engine valve of FIG.

FIG. 3 is a vertical cross-sectional view of a valve fully closed state of an incorporated portion in which the engine valve of FIG. 1 is incorporated in an engine.

FIG. 4 is a vertical cross-sectional view of an assembled portion of the engine valve of FIG. 1 assembled into an engine in a fully opened state.

[Explanation of symbols]

1 ... Valve body, 2 ... Valve shaft, 2A ... Outer peripheral surface portion, 5 ... Sliding contact range,
5a ... lower sliding contact range, 5b ... upper sliding contact range, 6 ... hardening part, 12 ... valve guide, 12a ... lower end, 12b ... upper end.

Claims (3)

[Claims] 1. An upper sliding contact range in which an upper end of the valve guide is in sliding contact and a lower end of the valve guide in a sliding contact range of an outer peripheral surface of a valve shaft of a martensitic heat-resistant steel engine valve in sliding contact with the valve guide. An engine valve in which a hardened portion by quenching treatment is provided in a lower sliding contact area where the sliding contact is made, and the outer peripheral surface portion is finished. 2. The depth of the hardened portion by quenching is 0.1 to
The engine valve according to claim 1, which is 1.0 mm. 3. The surface roughness of finishing is 0.1 to 5.0 μm.
The engine valve according to claim 1, which is mRz.