JPS595762B2 - mushroom valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mushroom-shaped valve, particularly a mushroom-shaped valve suitable for an intake and exhaust valve of an internal combustion engine.

A conventional mushroom valve used as an exhaust valve for an internal combustion engine is shown in FIGS. 1 and 2. This mushroom-shaped valve is exposed to high-temperature, high-pressure exhaust gas, and is placed in a high-temperature and highly corrosive environment. In particular, the seat portion 03 and the valve seat 04 are frequently removed and removed, so the material used for the mushroom-shaped valve is highly heat-resistant,
Abrasion resistant is required. Therefore, the seat portion 03 is generally overlaid with a sheet member 031 made of a material much harder than the material of the umbrella portion 01 and the stem portion O2, such as stellite. Stellite, which is most commonly used as the seat member 031, has various hardnesses depending on its components, but if a relatively soft material is used, the seat will separate from the valve seat 04 when the exhaust valve is seated. Non-combustible matter (combustion residue) mixed in the fuel gets caught on the surface 032, creating an impression (indentation) on the seat surface 032, and if this continues in the width direction of the seat part (Z direction in Fig. 1), the valve will not be seated. Sometimes, combustion gas blows through the gap between the recesses and the airtightness of the valve is compromised. Therefore, from the viewpoint of preventing the formation of impressions, extremely hard Stellite is used for the sheet member 031.

However, when overlaying hard stellite, advanced overlay welding techniques are required, and as the hardness of the stellite increases, its elongation decreases, which is mainly caused by temperature fluctuations when starting and stopping the engine. Umbrella part 01
There are also problems such as cracks occurring in the sheet member 031 due to thermal stress of the seat portion 03, and combustion gas blowing through the cracks. As mentioned above, in the conventional type, whether the seat member 031 is soft or hard, the blow-by phenomenon of combustion gas is unavoidable, although the cause is different. It was the main cause. For reference, an example of the hardness distribution of the seat member 031 and the umbrella member 01 of the conventional mushroom-shaped valve as described above is shown in FIGS. 3 and 4. 3 shows the hardness distribution in the direction perpendicular to the umbrella surface 011 in the vicinity of the seat portion 03 indicated by the arrow a-a in FIG. 1, and FIG. This is the distribution of hardness in the circumferential direction on the surface at the position indicated by -c. As mentioned above, in the conventional case, blow-by of combustion gas was unavoidable regardless of whether the sheet member 031 was hard or soft.However, normally, the sheet member 031 is made of a relatively soft material and The current situation is to prevent the occurrence of such cracks and to allow the occurrence of indentations due to combustion residue. The present invention has been made in view of the above, and an object of the present invention is to provide a highly durable mushroom-shaped valve that prevents combustion gas from blowing through the seat portion and cracks from occurring on the seat surface.

In order to achieve this object, the present invention builds up a seat member that is harder than the base material of the valve over the entire circumference of the seat part, carves a plurality of grooves on the seat surface of the seat member, and inserts a plurality of grooves into the grooves. It is characterized in that it is constructed so that two or more types of metals having different hardness are exposed on the sheet surface by burying a metal harder than the sheet member. One embodiment of the present invention will be described below with reference to FIGS. 5, 6, and 9. Fifth
The figure is a sectional view taken along the line A-A in FIG. 1, and in the same figure, 1 is a valve umbrella part, 2 is a stem part, and 3 is a seat part.
As shown in FIGS. 6 and 9, the seat portion 3 of the valve is made of stellite #6 #12, which is harder than the base material of the valve but relatively soft.
A sheet member 31 consisting of the like is overlaid by welding. Thereafter, a plurality of grooves 5 are cut along the entire circumference of the ring-shaped sheet surface 32 of the sheet member 31. Further, a metal 6 which is harder than the sheet member 31 is fused within the plurality of grooves 5 to finish the sheet surface 32 into a smooth surface. As for the metal fused in the groove 5, the material of the sheet member 31 is Stellite #6.
Or in the case of Stellite #12 (hardness HV4OO~500), Cormolloy #6 (chromium 13~14%, Poron 3
~4%, carbon 0.7-0.8%, silicon 4.0-4.5
%, iron 4.5-5.0%, nickel balance, and hardness of Hv7OO-800. ) is preferred.
The thickness t of the welded metal 6 (that is, the depth of the groove 5) is suitably about ⅓ of the thickness T of the sheet member 31. As a result of the above, the sheet surface 32 has two metal layers having different hardnesses, that is, the layer of the hard weld metal 6 and the layer of the sheet member 31 that is softer than the weld metal 6 in the width direction (d--2 in FIG. 9). d direction) and are alternately exposed.

When a mushroom-shaped valve with such a configuration is applied to an exhaust valve of an internal combustion engine, the seat surface 32 that comes into contact with and separates from the valve seat of the valve has a hardness that is higher than the fusion metal 6 and the fusion metal. The sheet member 31 which is soft and has high fatigue strength is attached to the sheet surface 32.
They are exposed alternately in the width direction. Therefore, if combustion residue or the like gets caught on the sheet surface 32, even if an indentation occurs in the relatively soft portion of the sheet member 31, the indentation will occur in the hard welded metal portion in the width direction of the sheet surface 32. (direction dd in FIG. 9) is prevented from growing. Therefore, the blow-by of combustion gas from the seat surface 32 due to the impressions is prevented from occurring.

In addition, since the sheet member 31 is softer and has greater fatigue strength than the weld metal 6, even if a crack occurs in the weld metal 6 due to thermal stress, the sheet member 31 will break the width of the sheet surface 32. Prevents the propagation of cracks in the direction. That is, in the present invention, the sheet surface 32 is formed by appropriately combining the fused metal 6, which is less likely to cause indentation due to the bite of combustion residue, and the sheet member 31, which is less likely to crack due to thermal stress, etc.
By forming this, it is possible to prevent combustion gas from blowing through from the sheet surface 32.

In the above embodiment, the welding metal 6 was one type of metal, but the welding metal 6 was made of a material harder than the sheet member 31, and (a) from the outer peripheral side to the inner peripheral side of the sheet surface 32; The material has two or more types of hardness, with the hardness increasing as the hardness increases.

(b) The hardness at the central portion of the seat surface 32 is greater than that at the outer and inner circumferential portions.

(c) The hardness of the inner circumferential side (or outer circumferential side) of the seat surface 32 is particularly greater than that of other parts. Two or more kinds of fusion metals 6 having different hardnesses can be used in combination as appropriate. FIG. 10 shows the hardness distribution in the width direction of the seat surface 32 (direction dd in FIG. 9) and the umbrella portion 1 in the first embodiment.
Distribution of hardness of the base material of the valve in (direction ee-e in Fig. 9)
This figure shows an example of measurement results. FIG. 1 shows another embodiment of the invention. This case is similar to the first embodiment described above in that the layers of the hard welded metal 6 and the softer sheet member 31 are exposed alternately in the width direction of the sheet surface 32. Therefore, the shape of the cross section along the line C-C in FIG. 7 is also the same as that in FIG. The difference is that it is divided and formed. In this embodiment, since the layer of hard welding metal 6 is discontinuous in the circumferential direction of the sheet surface 32, it is possible to prevent cracks from progressing in the circumferential direction in the welding metal 6. FIG. 8 shows yet another embodiment of the invention. In this case, the seat surface 32
A circular groove is carved irregularly on the top, and a sheet member 31 is inserted into the groove.
The metal 6, which is harder than the metal 6, is fused and has the same effect as the embodiment shown in FIG. In addition, D-D in Figure 8
The shape of the cross section along the line is also similar to that in FIG. As described above, in the mushroom-shaped valve according to the present invention, a sheet member harder than the base material of the valve is built up over the entire circumference of the seat portion, and a plurality of grooves carved in the seat surface of the seat member are filled with a sheet member that is harder than the base material of the valve. By filling the groove with a metal harder than the sheet member, two or more metals with different hardness are exposed alternately in the width direction of the sheet surface, so the hard metal buried in the groove prevents combustion. A sheet that prevents the growth of indentations along the width direction of the sheet surface due to biting of residue, etc., and is softer and has greater fatigue strength than the metal in the grooves even if cracks occur in the metal in the grooves. The member can prevent the crack from progressing in the width direction of the sheet surface.

Therefore, even if dents or cracks occur on the sheet surface, these will not continue to occur in the width direction of the sheet surface and will not be promoted, making it possible to prevent combustion gas from blowing through from the sheet surface. .

[Brief explanation of the drawing]

1 and 2 show an example of a conventional mushroom-shaped valve used as an exhaust valve for an internal combustion engine. It is a sectional view along the AA line. Figures 3 and 4 are one of the results of measuring the hardness of the conventional valve mentioned above.
FIG. 3 is a diagram illustrating an example. 5, 6 and 9 show one embodiment of the present invention, FIG. 5 is a diagram corresponding to FIG. 2, FIG. 6 is an enlarged view of the Y section in FIG. 5, and FIG. FIG. 9 is a sectional view taken along line B--B in FIG. 6. FIG. 7 is a diagram showing another embodiment of the present invention and corresponds to FIG. 6, and FIG. 8 is a diagram corresponding to FIG. 6 showing still another embodiment of the present invention. FIG. 10 is a diagram showing the hardness distribution. 1...
・Umbrella part, 2... Stem part, 3... Seat part, 31... Seat member, 32...
Sheet surface, 5...Groove, 6...Fusion metal.

Claims (1)

[Claims] 1. A seat member that is harder than the base material of the valve is built up over the entire circumference of the seat portion of the valve, and a plurality of grooves are carved in the annular seat surface of the seat member that comes into contact with and separates from the valve seat, and a plurality of grooves are carved in the grooves. A mushroom-shaped valve characterized in that a metal harder than the sheet member is embedded in the sheet member, and two or more metals having different hardness are alternately exposed in the width direction of the sheet surface.