JP2018013065A - Engine valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine valve capable of suppressing the temperature rise of the engine valve and also suppressing heat transfer from an umbrella part to a shaft part to suppress a deterioration in the intake efficiency of an engine.SOLUTION: An engine valve 20 for opening/closing an intake port of the engine has a shaft part 22 and an umbrella part 30. The shaft part 22 is formed of a first metallic material, and an umbrella surface portion 30a and a face portion 34 continuous with each other, out of the umbrella part 30, are each formed of a second metallic material having higher heat conductivity than the first metallic material.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an engine valve for intake air.

  When an intake valve (hereinafter referred to as “engine valve”) of an engine (internal combustion engine) becomes high temperature, fuel and oil adhering to the engine valve are steamed and a deposit is formed. If the fuel adsorbed in the deposit is detached or the deposit peels off and enters the combustion chamber due to an impact at the time of opening or closing the engine valve, the fuel component in the combustion chamber becomes excessive and the A / F becomes small. Therefore, the engine may become unstable in combustion. In addition, the peeled deposit may be caught between the engine valve and the valve seat of the engine, and the engine valve may not be completely closed. Therefore, in order to reduce the formation of deposits, it has been conventionally required to suppress the temperature rise of the engine valve.

  As one means for suppressing the temperature rise of the engine valve, it is known that the engine valve is formed of an aluminum alloy having a high thermal conductivity. For example, the engine valve described in Patent Document 1 is formed of an Al-based MMC (Metal Matrix Composites) in which a shaft portion and an umbrella portion are reinforced with an aluminum alloy with fiber particles or the like. As a result, the heat transmitted from the combustion chamber to the umbrella surface of the umbrella part is quickly transmitted to the face part, which is the contact part with the valve seat, and is radiated from the face part to the valve seat, thereby suppressing the temperature rise of the engine valve. Is done.

JP-A-7-63019

  However, when both the shaft portion and the umbrella portion are formed of Al-based MMC having high thermal conductivity as in the engine valve of Patent Document 1, the temperature of the shaft portion also increases because the heat of the umbrella portion is transmitted to the shaft portion. . As a result, when the air supplied to the combustion chamber flows along the shaft portion, the temperature rises and the volume increases, which causes a problem that the intake efficiency of the engine decreases.

  The present invention has been made to solve the problems as described above, and the problem is that the temperature rise of the engine valve can be suppressed, and the heat transfer from the umbrella portion to the shaft portion is suppressed to reduce the intake efficiency of the engine. An object of the present invention is to provide an engine valve capable of suppressing the decrease.

  The engine valve of the present invention is an engine valve that opens and closes an intake port of an engine, and includes a shaft portion and an umbrella portion, and an umbrella front portion of the umbrella portion and a face portion continuous from the umbrella front portion, It is formed of a second metal material having a higher thermal conductivity than the first metal material forming the shaft portion. With this configuration, the heat received at the front of the umbrella can be quickly transmitted to the valve seat of the engine via the face portion, so that the temperature rise of the engine valve can be suppressed. In addition, since the shaft portion is formed of the first metal material having a lower thermal conductivity than the second metal material forming the umbrella front portion, heat transfer from the umbrella portion to the shaft portion is suppressed, and the engine A reduction in intake efficiency can be suppressed.

  The second metal material is preferably aluminum or an aluminum alloy, or copper or a copper alloy. Since the second metal material is made of a material having a high thermal conductivity and a relatively low price, heat from the engine valve can be quickly radiated while suppressing the production cost.

  A concave curved surface that is continuous from the shaft portion to the umbrella back portion of the umbrella portion is formed. The umbrella portion forms an inner peripheral portion on the umbrella back side, and an inner periphery forming portion that is continuous with the shaft portion; Forming an outer peripheral portion on the umbrella back side that surrounds the circumferential forming portion in the circumferential direction and having an outer peripheral forming portion including an umbrella front portion and a face portion, and the inner peripheral forming portion is formed of a first metal material, The forming portion is formed of a second metal material, and the first metal material has higher toughness than the second metal material, and forms the outer periphery forming portion with the first metal material forming the inner periphery forming portion. The joint surface on the back side of the umbrella with the second metal material is preferably disposed closer to the face part than the center part of the concave curved surface in the radial direction of the umbrella part. With this configuration, the portion that is likely to be stressed when the engine valve is opened and closed is formed of the first metal material having high toughness, so that deformation of the engine valve can be suppressed.

  Moreover, it is preferable that the outer periphery formation part has a cover part which covers the umbrella back side of the outer peripheral edge part of an inner periphery formation part. With this configuration, the inner circumference forming portion can be more firmly joined to the outer circumference forming portion.

It is a front view of the engine valve concerning one embodiment. It is a front view which shows the surrounding part of the umbrella part of an engine valve partly broken. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1. It is sectional drawing which shows the peripheral part of the engine valve for engine intake in a valve opening state. It is sectional drawing which shows the peripheral part of the engine valve for engine intake in a valve closing state.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. For convenience of explanation, the configuration of the peripheral portion of the engine valve for intake of the engine will be described, and then the engine valve will be described. FIG. 4 is a cross-sectional view showing a peripheral portion of an engine valve for intake of the engine in an open state, and FIG. 5 is a cross-sectional view showing the same in a closed state. The engine valve will be described with reference to the vertical direction in FIGS. 4 and 5.

  As shown in FIG. 4, an intake port 12 communicating with the combustion chamber 11 is formed in the cylinder head 10 of the engine (internal combustion engine). A valve seat 13 is disposed at the downstream end of the intake port 12. The cylinder head 10 is provided with a metal valve guide 14 concentric with the valve seat 13. An engine valve 20 that opens and closes the intake port 12 is supported on the valve guide 14 so as to be slidable in the axial direction (vertical direction in FIG. 4). When the engine valve 20 is opened, the umbrella portion 30 of the engine valve 20 is separated from the valve seat 13 so that air flows into the combustion chamber 11 through the intake port 12. Further, when the engine valve 20 is closed (see FIG. 5), the umbrella portion 30 is seated on the valve seat 13, thereby preventing air from flowing into the combustion chamber 11 from the intake port 12.

  Next, the engine valve 20 will be described. FIG. 1 is a front view of the engine valve 20, FIG. 2 is a front view showing a part of the periphery of the umbrella portion 30 in a partially broken view, and FIG. 3 is a cross-sectional view taken along line III-III in FIG. As shown in FIG. 1, the engine valve 20 is a poppet valve having a shaft portion 22 and an umbrella portion 30 concentrically. An annular groove 24 continuous in the circumferential direction is formed on the outer peripheral surface of the upper end portion of the shaft portion 22. Although not shown, the annular groove 24 is a mounting groove for a retainer of the valve spring in the valve operating mechanism.

  As shown in FIG. 2, the umbrella part 30 has the inner periphery formation part 31 formed with the 1st metal material, and the outer periphery formation part 32 formed with the 2nd metal material. The inner periphery forming part 31 is continuous with the shaft part 22 which is also formed of the first metal material, and forms an inner peripheral part on the umbrella back side of the umbrella part 30 whose diameter is expanded downward. On the other hand, the outer periphery forming portion 32 forms an outer peripheral portion on the umbrella back side that surrounds the inner periphery forming portion 31 in the circumferential direction, and covers the umbrella front side of the inner periphery forming portion 31, that is, the side opposite to the shaft portion 22. . The detailed shape of the umbrella part 30 will be described later.

  The first metal material may be any metal material as long as it satisfies the wear resistance, strength, and corrosion resistance required for the shaft portion 22 and the inner periphery forming portion 31, and specific examples include steel and titanium. . Further, as will be described later, since the first metal material is used in a portion where stress is easily generated when the engine valve 20 is opened and closed, it is preferable that the toughness is larger than that of the second metal material. The toughness of each material can be measured and compared by, for example, a Charpy impact test.

  On the other hand, the second metal material may be any metal material as long as it satisfies the wear resistance required for the contact portion with the valve seat 13 and has a higher thermal conductivity than the first metal material. Therefore, it can be appropriately selected in consideration of thermal conductivity and wear resistance with respect to the material of the valve seat 13 (for example, iron or copper). Specifically, aluminum, an aluminum alloy, copper, and a copper alloy are preferable because they have high thermal conductivity and are relatively inexpensive. In order to ensure the required wear resistance, for example, in the case of an aluminum alloy, there is a method of containing 15% Si and precipitating Si, and in the case of a copper alloy, Si and Mn are contained, There is a method of depositing manganese silicide.

  The engine valve 20 can be formed by sintering, casting, forging, or the like. First, the shaft portion 22 and the inner periphery forming portion 31 of the umbrella portion 30 are integrally formed, and then the outer periphery forming portion 32 is formed around the inner periphery forming portion 31 to form the umbrella portion 30.

  Next, the detailed shape of the umbrella part 30 will be described. As shown in FIG. 2, the umbrella part 30 has the umbrella front part 30a which faces the combustion chamber 11 (refer FIG. 4) of an engine in a lower end. The umbrella front portion 30 a is formed in a disk shape that is coaxial with the shaft portion 22. On the other hand, an annular face portion 34 that is continuous upward from the umbrella front portion 30a is formed on the back side of the umbrella portion 30, that is, on the outer peripheral portion opposite to the umbrella front portion 30a. The surface of the face portion 34 is reduced in diameter upward from the outer peripheral end of the umbrella front portion 30a, and is formed in a tapered surface having a linear cross section. The face portion 34 is a portion that contacts the valve seat 13 of the engine when the valve is closed.

  Moreover, the umbrella part 30 has an annular slope part 36 extending upward from the end part on the small diameter side of the face part 34. The surface of the slope portion 36 is reduced in diameter upward from the outer peripheral end on the small diameter side of the face portion 34 and is formed into a tapered surface having a linear cross section. The face portion 34 and the slope portion 36 constitute an umbrella back portion 30b. Moreover, the umbrella front part 30a, the face part 34, and the slope part 36 are included in the outer periphery formation part 32 formed of the second metal material.

  As shown in FIG. 2, the inner periphery forming portion 31 has a diameter that increases downward, and the outer peripheral surface thereof has a concave curved surface 38 that smoothly continues from the shaft portion 22 to the surface of the umbrella back portion 30 b of the umbrella portion 30. It has become. The concave curved surface 38 is formed in a curve having a predetermined radius of curvature in a cross section along the axial center of the engine valve 20. The lower end portion of the inner periphery forming portion 31 is surrounded by the outer periphery forming portion 32 in the circumferential direction, and the lower surface thereof is also covered by the outer periphery forming portion 32. The outer periphery forming portion 32 has a cover portion 40 that covers the umbrella back side of the outer peripheral end portion of the lower end portion of the inner periphery forming portion 31, that is, the upper portion. Since the cover part 40 prevents the inner periphery forming part 31 from being detached upward from the outer periphery forming part 32, the joint between the inner periphery forming part 31 and the outer periphery forming part 32 can be made stronger. The cover part 40 is constituted by a part of the slope part 36.

  As shown in FIG. 3, the lower end part of the inner periphery formation part 31 is a cross-sectional shape which has several unevenness | corrugations in the circumferential direction. The cross-sectional shape of the lower end portion of the inner periphery forming portion 31 may be concentric with the outer periphery forming portion 32. However, by providing unevenness, the bonding between the inner periphery forming portion 31 and the outer periphery forming portion 32 is made stronger. Can do.

  Further, as shown in FIG. 2, the joint surface between the inner periphery forming part 31 and the outer periphery forming part 32 on the back side of the umbrella, that is, the joint surface between the first metal material and the second metal material is the radius of the umbrella part 30. It is arranged closer to the face 34 than the center of the concave curved surface 38 in the direction. The joint surface between the inner periphery forming portion 31 and the outer periphery forming portion 32 is such that a distance d from the axial center of the engine valve 20 to the outer periphery of the inner peripheral forming portion 31 is an umbrella portion in the radial direction from the axial center of the engine valve 20. It is preferable that the maximum outer diameter D is 30 or more and 2/3 or less. The toughness of the second metal material forming the outer periphery forming portion 32 is small, and the inner periphery forming portion 31 and the outer periphery forming portion 32 are joined at a position closer to the axial center of the engine valve 20 than the central portion of the concave curved surface 38. When the intake port 12 is open, the outer periphery forming portion 32 may be plastically deformed by the tensile stress generated when the intake port 12 is opened and closed. The central portion of the concave curved surface 38 corresponds to a position that bisects the curve formed by the concave curved surface 38 in the cross section along the axial center of the engine valve 20.

  On the other hand, the lower surface of the inner periphery forming part 31 is a joint surface on the umbrella front side with the outer periphery forming part 32 forming the umbrella front part 30a. In the axial direction of the engine valve 20 (vertical direction in FIG. 2), the thickness h of the outer periphery forming portion 32 in the region facing the lower surface of the inner periphery forming portion 31, that is, from the lower end of the umbrella front portion 30a to the inner periphery forming portion 31. The distance to the lower end is preferably not less than 0.5 times and not more than 1.5 times the face height H, that is, the distance from the lower end of the umbrella front portion 30a to the upper end of the face portion 34. If h is less than 0.5 times H, when the temperature of the umbrella part 30 rises, the umbrella part 30 may crack due to the difference in thermal expansion coefficient between the first metal material and the second metal material. There is. On the other hand, if h exceeds 1.5 times H, it becomes difficult to form a joint shape between the inner periphery forming portion 31 and the outer periphery forming portion 32. In FIG. 2, the lower surface of the inner periphery forming portion 31 is parallel to the lower surface of the umbrella front portion 30a and the value of h is constant, but the value of h may not be constant as long as it is within the above range. For example, h may be formed so as to gradually increase from the axial center of the umbrella portion 30 toward the outer periphery, and in this case, heat transfer to the face portion 34 can be performed more efficiently, so that the valve seat Heat dissipation to 13 is further promoted.

  According to the engine valve 20 described above, since the shaft portion 22 is formed of the first metal material having a lower thermal conductivity than the second metal material forming the outer periphery forming portion 32 of the umbrella portion 30, the umbrella portion 30 is formed. Heat transfer from the shaft portion 22 to the shaft portion 22 can be suppressed, and a temperature rise of the shaft portion 22 can be suppressed. Thereby, the temperature rise of the air which flows through the intake port 12 can be suppressed, and the fall of the intake efficiency of an engine can be prevented.

  In addition, the umbrella surface portion 30a and the face portion 34 that are continuous with each other in the umbrella portion 30 are formed of the second metal material having a high thermal conductivity, so that the heat transmitted from the combustion chamber 11 to the umbrella surface portion 30a is transmitted. By promptly transmitting to the face portion 34 and radiating heat from the face portion 34 to the valve seat 13, the temperature rise of the engine valve 20 can be suppressed. Therefore, deposit formation in the engine valve 20 can be reduced.

  Further, the first metal material forming the shaft portion 22 and the inner periphery forming portion 31 and the second metal material forming the outer periphery forming portion 32 are more than the central portion of the concave curved surface 38 in the radial direction of the umbrella portion 30. Bonded on the face part 34 side. As a result, even if the outer periphery forming portion 32 is formed of a metal material with low toughness, the portion where stress is likely to occur when the engine valve 20 is opened and closed is formed of the first metal material with high toughness. 20 deformation can be prevented.

  The present invention is not limited to the above-described embodiment, and modifications can be made without departing from the gist of the present invention. For example, the inner periphery forming portion 31 of the shaft portion 22 may not have the concave curved surface 38 on the outer peripheral surface. In that case, in the radial direction of the engine valve 20, the distance d from the axial center of the engine valve 20 to the outer periphery of the inner periphery forming portion 31 is ½ of the maximum outer diameter D of the umbrella portion 30 from the axial center of the engine valve 20. As described above, the joint surface between the inner periphery forming portion 31 and the outer periphery forming portion 32 may be disposed so as to be 2/3 or less.

DESCRIPTION OF SYMBOLS 10 Cylinder head 11 Combustion chamber 12 Intake port 13 Valve seat 20 Engine valve 22 Shaft part 30 Umbrella part 30a Umbrella front part 30b Umbrella back part 31 Outer periphery formation part 32 Outer periphery formation part 34 Face part 36 Slope part 38 Concave surface 40 Cover part

Claims (5)

An engine valve that opens and closes the intake port of the engine,
Having a shaft and an umbrella,
Among the umbrella parts, an umbrella front part and a face part continuous from the umbrella front part are formed of a second metal material having a higher thermal conductivity than the first metal material forming the shaft part. And engine valve. The engine valve according to claim 1,
The engine valve according to claim 1, wherein the second metal material is aluminum or an aluminum alloy. The engine valve according to claim 1,
The engine valve, wherein the second metal material is copper or a copper alloy. The engine valve according to any one of claims 1 to 3,
A concave curved surface that is continuous from the shaft portion to the umbrella back portion of the umbrella portion is formed,
The umbrella part forms an inner peripheral part on the back side of the umbrella and forms an inner peripheral part that is continuous with the shaft part, and an outer peripheral part on the back side of the umbrella that surrounds the inner peripheral part in the circumferential direction. An outer periphery forming portion including a front portion and the face portion;
The inner periphery forming portion is formed of the first metal material,
The outer periphery forming portion is formed of the second metal material,
The first metal material is tougher than the second metal material,
The joint surface of the back side of the first metal material forming the inner periphery forming portion and the second metal material forming the outer periphery forming portion is a central portion of the concave curved surface in the radial direction of the umbrella portion. The engine valve is arranged closer to the face portion than the engine valve. The engine valve according to claim 4,
The engine valve according to claim 1, wherein the outer periphery forming portion includes a cover portion covering an umbrella back side of an outer peripheral end portion of the inner periphery forming portion.

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