TW201540938A - Poppet valve - Google Patents

Abstract

Provided is a poppet valve which is configured so as to prevent all the three modes of heat transfer from occurring, thereby enabling maximum combustion efficiency to be achieved. A poppet valve has an umbrella section (14) integrally formed on one end side of a shaft section (12). A hollow section (19) extending along an umbrella front surface (24) is formed within the umbrella section (14). A metallic layer (17) for blocking radiation heat is formed on the ceiling surface (25) of the hollow section (19), and a heat insulating section is formed between the metallic layer (17) and the bottom surface of the hollow section (19). Among the modes of heat transfer, the conduction and convention are blocked by the heat insulating section, and the radiation is blocked by the metallic layer (17).

Description

Poppet valve

The present invention relates to a poppet valve that suppresses heat transfer from the combustion chamber, particularly heat generated by radiation.

Patent Document 1 describes a poppet valve in which an umbrella portion is integrally formed at a shaft end portion. A poppet valve used in an internal combustion engine is seated on a valve seat of a cylinder head to which an intake passage or an exhaust passage is connected to open and close the intake passage or the exhaust passage to drive the engine.

Generally, the less energy loss generated by the internal combustion engine in the combustion chamber, the higher the combustion efficiency. As a loss of energy, there is a cooling loss caused by heat scattering to the outside. The heat of the combustion chamber is mostly dissipated to the outside via the poppet valve or the inner wall of the combustion chamber. Therefore, a space is formed in or near the umbrella table of the poppet valve contacting the combustion chamber, and the space is set to be vacuum, filled with an inert gas, or filled with a material having a thermal conductivity lower than that of the material constituting the poppet valve. The heat insulating space is formed to suppress the dissipation of heat in the combustion chamber (see Patent Document 1).

The heat transfer (heat transfer) pattern has three types of heat conduction, convection, and radiation (heat radiation). The heat conduction system conducts heat by directly contacting the objects without moving the objects, and the convection system indirectly transfers heat through the medium of the fluid flow, and any one of them transfers heat in a state of thermal vibration. On the other hand, the radiation emits electromagnetic waves by the object that conveys the source, and the object to be transported absorbs the electromagnetic waves to transmit heat. In the case of radiation, There is no medium between the two objects, and even if it is a vacuum, it can transfer heat.

The heat transfer from the combustion chamber of the engine to the poppet valve is also produced by three types of heat conduction, convection and radiation. In the above-described Patent Document 1, a concave portion is formed on the valve head surface, and a heat insulating porous material is filled in the concave portion to suppress heat emission from the combustion chamber. As a material of the porous material, a non-woven fabric made of a heat-resistant metal such as stainless steel (paragraph 0036) is exemplified. However, in the usual heat insulating material, although the heat conduction and convection heat transfer in the heat transfer of the above three aspects can be interrupted, the radiant heat still passes, and accordingly, the temperature drop in the combustion chamber of the portion cannot be avoided. . Patent Document 1 does not describe anything about radiation, and does not consider the radiant heat to be interrupted.

Patent Document 2 discloses that an inner wall of a combustion chamber of an engine is covered with a heat insulating porous layer formed of ceramics and a heat insulating material of a surface dense layer formed of ceramics (paragraph 0023), and when the fuel is burned, The radiant heat is reflected by the surface dense layer (paragraph 0024).

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Special Opening 2012-72748

Patent Document 2: WO 2013/080389A1

[Non-patent literature]

Non-Patent Document 1: http://www.landinst.jp/info/faq/faq3.html

Non-Patent Document 2: http://www.fintech.co.jp/etc-data/housharitsu.htm

According to the review by the inventors, in the rough-faced nonwoven fabric described in Patent Document 1, the reflection of heat containing radiation hardly occurs, and the ceramic described in Patent Document 2 is contrary to the description of Patent Document 2, and no radiant heat is generated. Full reflection. For example, Non-Patent Document 1 and Patent Document 2 describe the emissivity of electromagnetic waves by metal or ceramics, and the emissivity is defined by (emissivity = 1 - reflectance - transmittance). From this, it is understood that when the emissivity is lowered, the reflectance is increased, and since the emissivity of the ceramic is relatively high from 0.4 to 0.95, the reflectance is relatively low, and the reflection efficiency of the electromagnetic wave is insufficient. The emissivity of aluminum and copper is 0.05 to 0.09, so the reflectance becomes quite high. The reflection by the metal is large because the action of the free electrons is large, and the electromagnetic wave is reflected by the group vibration of the free electrons, so that the reflection effect is high and the reflection has directivity. However, it is well known that aluminum and copper metals lack high temperature resistance and cannot be used in engines with combustion gas temperatures of 2000 ° C to 2500 ° C.

Further, in Patent Document 2, since the radiant heat reflecting means is provided at the outermost layer portion on the combustion chamber side, the heat resistance temperature required for the material is high, and since the applicable material is limited, the adhesion of the combustion residue and the oxide layer are generated. The reflection function is degraded. Therefore, even if the ceramic is applied to the valve head surface of the poppet valve of Patent Document 1, it does not function to suppress heat emission due to reflection of radiant heat.

The present invention has been accomplished on the basis of the inventors' knowledge of the prior art, and aims to provide a poppet valve that reflects the radiant heat from the combustion chamber of the poppet valve toward the direction of the combustion chamber, thereby suppressing heat dissipation caused by radiation. High combustion efficiency can be maintained for a long period of time and stably.

In the poppet valve according to the first aspect of the invention, the poppet valve is integrally formed on the one end side of the shaft portion, and the poppet portion is formed in the umbrella portion. The heat insulating portion on the combustion chamber side and the metal layer on the shaft portion side to block the radiant heat.

(Action) If a poppet valve composed of such a structure is used as an engine valve, the combustion flame generated by the combustion of the fuel in the combustion chamber and the heat of the combustion gas generated by the combustion are in the form of heat conduction, convection, and radiation. Transfer from the combustion chamber to the poppet valve. The heat of the combustion gas is applied to the combustion chamber side of the valve head of the umbrella portion of the valve body, and the heat insulating space or the heat insulating region (insulation portion) filled with the heat insulating material in the heat insulating space is caused by Thermal conduction and thermal escaping caused by convection. The radiant heat of the heat is transmitted as an electromagnetic wave, and is contacted with the shiny metal through the heat insulating region.

Since heat generated by heat conduction and convection is blocked by the heat insulating portion, the metal is not reached, so that the temperature of the combustion gas contacting the metal is greatly reduced, and even a metal lacking high temperature resistance does not deteriorate. The radiant heat is reflected in the direction of the combustion chamber, and does not penetrate the valve body for dissipation, and the radiant heat is retained in the combustion chamber to prevent the cooling of the combustion gas generated by the valve, thereby improving the combustion efficiency. In particular, the metal receives heat of the combustion gas passing through the heat insulating portion, in other words, heat mainly caused by radiation that cannot be blocked in the heat insulating portion, and does not allow heat of the combustion gas to be directly transmitted to the metal, so that the material has a low heat resistance temperature. It can also be used in the middle. Further, since the radiant heat reflecting means is provided inside the valve, it is possible to prevent the deterioration of the reflection ability due to the adhesion of the combustion residue or the like or the generation of the oxide layer. Further, the metal of the present invention further contains a metal alloy.

The metal layer of the present invention needs to have radiant heat barrier properties. A metal having radiant heat occlusion property usually has a glossy surface or a mirror surface, but may not have a glossy surface or a mirror surface, and may be used as the metal of the present invention as long as it has radiant heat occlusion property. Glossy or mirrored surface can be used in the absence of radiant heat-shielding metals The treatment imparts radiant heat barrier properties and is used as the metal of the present invention. In particular, if the temperature of the combustion gas generated in the combustion chamber is 2,500 ° C, the wavelength of the radiation generated by the heat of the combustion gas is 1.0 μm (the wavelength of 1500 ° C is 1.6 μm) according to Wayne's law of displacement. Since the reflectance of the metal in the above wavelength region is high, the radiant heat blocking property is increased. Thereby, the metal which can be used in the present invention has a radiant heat rupture property much larger than that of ceramics or the like.

According to a second aspect of the present invention, in the poppet valve according to the first aspect of the present invention, a hollow portion extending along the umbrella table is formed in the umbrella portion, and a metal layer that blocks radiant heat is formed on a top surface of the hollow portion. A heat insulating portion is formed between the metal layer and the bottom surface of the hollow portion.

(Action) In the poppet valve constituted by such a structure, the hollow portion is filled with a heat insulating material of a gas or a low heat conductive material, or the hollow portion is maintained in a vacuum. The most suitable thermal blocking effect can be obtained by appropriately selecting the conditions of the hollow portion.

According to a third aspect of the invention, in the poppet valve of the first aspect of the invention, the metal layer that blocks the radiant heat is formed on the bottom surface of the umbrella portion, and the metal layer of the metal layer that blocks the radiant heat is formed on the combustion chamber side. Insulating surface treatment layer.

(Action) In the poppet valve constituted by such a structure, since the hollow portion is not formed, the manufacturability of the valve can be improved.

According to a fourth aspect of the invention, in the poppet valve of the first aspect of the invention, the metal is selected from the group consisting of aluminum, copper, and aluminum alloy. Metals other than aluminum constituting the aluminum alloy include copper, manganese, lanthanum, magnesium, zinc, nickel, and the like.

(Action) Since aluminum or copper is relatively lightweight and has high radiant heat reflection efficiency, it is a suitable material. Aluminum alloys also have radiant heat reflecting energy, which can achieve an improvement in fuel consumption.

According to a fifth aspect of the invention, in the poppet valve according to the first or second aspect of the invention, the metal is in a foil shape or a sheet shape. The aluminum foil or the copper foil usually has gloss itself, and it can be directly attached to the combustion chamber side of the valve head via the heat insulating region, etc., so that the heat generated by the radiant heat reflection can be prevented from scattering to the outside, and can contribute to Improved fuel consumption due to improved combustion efficiency. Further, in the case where the metal is formed into a sheet shape, the radiant heat can be reflected by being used at a predetermined position.

According to a sixth aspect of the invention, in the poppet valve of the first aspect of the invention, the metal layer is a film formed by surface treatment selected from physical vapor deposition (PVD), spraying, and plating. The metal layer of the present invention may be a conventional foil or sheet, but a metal layer may be formed by the above surface treatment, and by such surface treatment, a metal layer having high radiant heat rupturability can be formed.

According to the poppet valve of the present invention, by effectively blocking the heat transfer of the combustion flame and the heat of the combustion gas in the combustion chamber, heat transfer, convection and radiation, the heat generated in the combustion chamber is prevented from scattering to the outside, and the lift can be reduced. Loss of combustion efficiency caused by cooling. Even if the high temperature resistance of the metal forming the metal layer having high radiant heat occlusion is insufficient, the heat of the combustion gas is removed by heat conduction and convection by the heat insulating portion, and only the heat caused by the radiation reaches the metal layer. Therefore, almost no metal deterioration occurs.

2‧‧‧ cylinder head

3‧‧‧ valve through hole

3a‧‧‧ valve guidance

4‧‧‧ combustion chamber

6‧‧‧Exhaust passage

8‧‧‧ valve seat

9‧‧‧Valve spring

10, 10A, 10B‧‧‧ pull valve

11, 11A‧‧‧ body

12‧‧‧Axis

12B‧‧‧ Solid shaft

12b‧‧‧Axis end members

12c‧‧‧Bolt

13‧‧‧ fillet

14, 14B‧‧‧ Umbrella Department

14a‧‧‧ Umbrella shell

14b, 14b’‧‧‧ top

15‧‧‧ bottom

16‧‧‧Face

17, 17', 17" ‧ ‧ radiant heat reflecting surface (metal layer that blocks radiant heat)

18, 18’‧‧‧ cover

18a‧‧‧Bend

18b‧‧‧ arc-shaped ribs

18c‧‧‧Surface treatment insulation

19, 19'‧‧‧ Hollow (insulation, insulation)

21‧‧‧ Hollow

22‧‧‧Steps Department

23‧‧‧ Cooling materials

24, 24’‧‧‧ Umbrella

25, 25’‧‧‧ bottom

S‧‧‧Small hollow

Fig. 1 is a longitudinal sectional view showing a poppet valve according to a first embodiment of the present invention.

Figure 2 is an enlarged cross-sectional view taken along line A-A of Figure 1.

Fig. 3 is a longitudinal sectional view showing a poppet valve according to a second embodiment of the present invention.

Fig. 4 is a longitudinal sectional view showing a poppet valve according to a third embodiment of the present invention.

Embodiments of the present invention will now be described based on the embodiments.

Fig. 1 and Fig. 2 show a hollow poppet valve for an internal combustion engine according to a first embodiment of the present invention.

In Fig. 1, reference numeral 10 denotes a heat-resistant alloy poppet valve in which a valve umbrella portion 14 is integrally formed on one end side of a straight-line extending valve shaft portion 12 via an R-shaped corner portion 13 whose outer diameter is gradually increased, and A tapered surface portion 16 is provided on the outer circumference of the valve umbrella portion 14. An umbrella casing 14a is integrally formed on one end side of the shaft portion 12 to constitute a valve body 11.

The top surface 14b of the umbrella portion 24 of the valve umbrella portion 14 is formed by spraying or the like and is joined with a radiant heat reflecting surface made of a metal having a mirror-like foil or sheet shape (the metal that blocks the radiant heat) The layer 17 is joined by a metal formed into a sheet by welding or the like. As a metal which can be used, it has aluminum or copper, and contains an alloy of such a metal, particularly aluminum.

Usually, since the foil-like metal has a mirror surface and has radiant heat occlusion property, it can be used as it is, but the metal formed by the sheet shape or by surface treatment sometimes does not have sufficient radiant heat rupture property. At this time, it is necessary to treat the surface to have a gloss to improve the radiant heat occlusion. As an example of the gloss treatment of metal, there is polishing of a metal surface.

Next, a lid body 18 is attached to the top surface 14b of the valve umbrella portion 14 on which the radiant heat reflecting surface 17 is formed. The lid body 18 has a circular plate shape including an upwardly bent portion 18a obtained by bending the peripheral edge portion upward, and a doughnut-shaped ring is equally divided on the inner side by integral molding or welding. Arc-shaped rib 18b. If by The upwardly bent portion 18a of the lid body 18 is fixed to the top surface 14b of the valve umbrella portion 14 by welding or the like, and the ribs 18b support the top surface 14b of the valve umbrella portion 14 via the radiant heat reflecting surface 17. A hollow portion 19 is formed between the upper surface of the lid body 18 and the top surface 14b of the valve umbrella portion 14. By setting the inside of the space to be formed into a vacuum, heat conduction from the combustion chamber side is insulated to function as a heat insulating space. Further, the space may be filled with a gas such as air or argon to function as a heat insulating space. In the case of Fig. 1, the upper surface of the lid body 18 is the bottom surface 25 of the hollow portion.

Further, reference numeral 2 in Fig. 1 denotes a cylinder head, reference numeral 6 denotes an exhaust passage extending from the combustion chamber 4, and an annular valve seat 8 is provided at an opening peripheral portion of the exhaust passage 6 toward the opening of the combustion chamber 4. The valve seat 8 is provided with a tapered surface on which the surface portion 16 of the valve 10 abuts. Reference numeral 3 is provided in a valve insertion hole of the cylinder head 2, and the valve insertion hole 3 is constituted by a cylindrical valve guide 3a to which the shaft portion 12 of the valve 10 is slid. Reference numeral 9 is a valve spring that applies a potential energy to the valve 10 in the valve closing direction (the upward direction in Fig. 1), and reference numeral 12c is a bolt groove provided at the end portion of the valve shaft portion 12. The shaft portion 12 is formed with a longitudinal hollow portion 21 for communicating the hollow portion (insulation portion) 19 and the lower surface of the shaft end member 12b.

Further, the portions of the high-temperature gas exposed to the combustion chamber 4 and the exhaust passage 6, that is, the valve body 11 and the lid body 18 are made of heat-resistant steel, and on the other hand, mechanical strength is required, but the valve body 11 and the cover are not required. The shaft end member 12b having a heat resistance of a size of 18 is composed of a general steel material.

When the fuel is combusted in the combustion chamber 4 of the hollow poppet valve 10 thus constructed, heat of the high-temperature combustion gas is generated, and the heat of the combustion gas passes through the cover 18 of the poppet valve 10 to reach the hollow portion. Hot part) 19. The heat transfer pattern of the combustion gas, that is, the heat conduction, the convection, and the radiation, the heat conduction and the convection, are blocked by the heat insulating portion 19, and the heat of the combustion gas does not pass from the radiant heat reflecting surface 17 to the valve umbrella portion 14. Directional delivery. The radiant heat in the heat of the combustion gas is reflected by the radiant heat reflecting surface 17 made of aluminum or the like, and then returned to the combustion chamber 4 through the lid body 18. Therefore, in the poppet valve 10 of the present embodiment, heat transfer, heat conduction, convection, and radiation of the combustion gas are suppressed, and energy generated by combustion of the fuel is taken as heat through the valve body to the outside. The amount is reduced (the cooling loss is reduced).

In the present embodiment, aluminum, copper or an aluminum alloy can be used as the material of the radiant heat reflecting surface, and it is known that unlike the ceramic described in Patent Document 2, a large amount of radiant heat can be reflected and returned to the combustion chamber.

Fig. 3 shows a poppet valve for an internal combustion engine according to a second embodiment of the present invention. The hollow poppet valve 10A of the second embodiment is a modification of the first embodiment, and the same members as those of the first embodiment are denoted by the same reference numerals and will not be described. In the second embodiment, a hollow portion 19' which is a spherical (dome-shaped) space is formed between the top surface 14b' and the bottom surface 25' of the disk-shaped lid body 18', except for the hollow portion 19'. The inner peripheral surface other than the lower end periphery is covered with a radiant heat reflecting surface 17', and the disk-shaped lid body 18' is fitted to the lower end of the hollow portion 19'. A small-diameter hollow portion S is formed upward from the upper surface of the radiant heat reflecting surface 17' in the shaft portion 12, and the small-diameter hollow portion S is filled with a cooling material 23 having a thermal conductivity higher than that of the base material of the engine valve (for example, Metal sodium, melting point of about 98 ° C) and inert gas. Further, since the step portion 22 is formed in the small-diameter hollow portion S, the coolant 23 in the small-diameter hollow portion S moves in the vertical direction when the valve material is moved in the vertical direction by the inertial force acting when the valve 10A is opened and closed. The turbulent flow is generated in the vicinity of the step portion 22, causing the cooling material 23 to be agitated, so that the heat conduction effect (thermal conductivity) in the valve shaft portion 12 can be improved. By blocking the heat of the combustion gas on the combustion chamber side, it does not escape through the valve, and the heat-resistant temperature required for the material can be lowered by the heat conduction effect of the valve shaft portion.

Fig. 4 shows a poppet valve for an internal combustion engine according to a third embodiment of the present invention. The hollow poppet valve 10B of the third embodiment is a modification of the first embodiment, and the same members as those of the first embodiment are denoted by the same reference numerals and will not be described. In the third embodiment, the umbrella portion 14B is integrally formed on the combustion chamber 4 side of the solid shaft portion 12B, and the hollow portion is not formed in the present embodiment. The bottom surface 15 of the umbrella portion 14B of the poppet valve 10B is formed with a radiant heat reflecting surface 17" so as not to be exposed at both ends, and a surface having a thermal conductivity of 3 W/mK or less is formed on the surface of the radiant heat reflecting surface 17". The heat insulating layer 18c is coated or coated with a plate-shaped low heat conductive material having a thermal conductivity of 3 W/mK or less. The surface treatment heat insulating layer 18c formed has the same effect as the heat insulating space of the hollow portion 19 of the first embodiment, and the heat of the high-temperature combustion gas generated in the combustion chamber is treated by the surface of the poppet valve 10B. 18c, reaching the radiant heat reflecting surface 17". The heat transfer mode of the combustion gas, that is, heat conduction, convection, and heat conduction and convection in the radiation, is blocked by the low thermal conductivity surface treatment heat insulation layer 18c, and the radiation is The radiant heat reflecting surface 17" is reflected by the combustion chamber 4. At this time, the radiant heat reflecting surface 17" is surrounded by the bottom surface 15 of the umbrella portion 14B and the surface treatment heat insulating layer 18c, and is not exposed to the gas atmosphere. Therefore, a metal having low heat resistance such as aluminum can also be used as the radiant heat reflecting surface 17" The material used. Therefore, in the poppet valve 10B of the present embodiment, heat transfer, heat transfer, convection, and radiation of the combustible gas are suppressed, and energy generated by combustion of the fuel is taken away as heat through the valve body. The amount is reduced (the cooling loss is small). The surface treatment heat insulating layer 18c having a low thermal conductivity is formed by atmospheric plasma spraying or the like.

2‧‧‧ cylinder head

3‧‧‧ valve through hole

3a‧‧‧ valve guidance

4‧‧‧ combustion chamber

6‧‧‧Exhaust passage

8‧‧‧ valve seat

9‧‧‧Valve spring

10‧‧‧Floating valve

11‧‧‧ valve body

12‧‧‧Axis

12B‧‧‧ Solid shaft

12b‧‧‧Axis end members

12c‧‧‧Bolt

13‧‧‧ fillet

14‧‧‧ Umbrella Department

14a‧‧‧ Umbrella shell

14b‧‧‧ top surface

16‧‧‧Face

17‧‧‧Radiating heat reflecting surface (metal layer that blocks radiant heat)

18‧‧‧ Cover

18a‧‧‧Bend

18b‧‧‧ arc-shaped ribs

19‧‧‧ Hollow (insulation, insulation)

21‧‧‧ Hollow

24‧‧‧Umbrella

25‧‧‧ bottom

Claims (6)

A poppet valve in which an umbrella portion is integrally formed on one end side of a shaft portion, wherein the umbrella portion is formed with a heat insulating portion on the combustion chamber side and a radiant heat on the shaft portion side. The metal layer that is interrupted. The poppet valve of claim 1, wherein a hollow portion extending along the umbrella table is formed in the umbrella portion, and a metal layer that blocks radiant heat is formed on a top surface of the hollow portion. A heat insulating portion is formed between the bottom surface of the hollow portion. The poppet valve of claim 1, wherein a metal layer that blocks radiant heat is formed on a bottom surface of the umbrella portion, and a heat insulating layer is formed on a combustion chamber side of the metal layer that blocks the radiant heat. Surface treatment layer. The poppet valve of any one of claims 1 to 3, wherein the metal is selected from the group consisting of aluminum, copper, and aluminum alloy. The poppet valve of any one of claims 1 to 4, wherein the metal is in the form of a foil or a sheet. The poppet valve of claim 1 or 2, wherein the metal layer is a film formed by surface treatment selected from physical vapor deposition (PVD), spraying, and electroplating.