WO2018191951A1

WO2018191951A1 - Engine valve with heat insulation sleeve for preventing high temperature failures

Info

Publication number: WO2018191951A1
Application number: PCT/CN2017/081426
Authority: WO
Inventors: 赵毛兴
Original assignee: 赵毛兴
Priority date: 2017-04-17
Filing date: 2017-04-21
Publication date: 2018-10-25

Abstract

Disclosed is an engine valve with a heat insulation sleeve for preventing high temperature failures, the engine valve comprising an engine valve body and a heat insulation sleeve (2), wherein the engine valve body is composed of a valve stem (1) and a disc portion (3), the heat insulation sleeve is nested on the valve stem, and one end of the heat insulation sleeve faces the disc portion. The valve with the insulation sleeve can significantly alleviate the heated state of the exhaust valve under the scouring of a high temperature exhaust gas, can significantly improve the quality of the valve, and can reliably perform normally continuous operation in the harsh environment of the engine, such that the process is simple and feasible, and the production cost is low.

Description

Engine valve with heat insulation sleeve to prevent high temperature failure

Technical field

The invention relates to the field of engine component manufacturing, in particular to a novel engine valve.

Background technique

The valve (Fig. 7) is a key component of the engine and is functionally divided into intake and exhaust valves. The intake valve opens, fresh air is sent to the combustion chamber, and the intake and exhaust valves are closed. The fuel passes through the carburetor and injects oil, ignites and explodes into the combustion chamber, and pushes the piston to work. The exhaust valve opens and discharges. High temperature exhaust gas after combustion.

When the engine is burning, the temperature of the gasoline engine can reach 1500--1800 °C, and the diesel engine can reach 1800--2200 °C. The exhaust gas temperature after combustion is also as high as 750--800 ° C. Under such severe working conditions, the exhaust valve is easily ablated and deformed, and the intake valve is cooled during the process of feeding fresh air. The heating condition is better. In view of the above situation, the manufacturing technology of the engine valve (hereinafter mainly referred to as the exhaust valve) is designed to ensure the wear resistance and corrosion resistance. The first task is to improve the strength of the valve at high temperature, which must be Steel model selection began, from alloy steel 40cr to 42cr9si2, 40cr10si2mo (martensitic heat-resistant alloy steel), and then to 53cr21mn9N14N (austenitic heat-resistant stainless steel), the price rose from several thousand to tens of thousands of tons, but Faced with the development of engine technology from low speed to high speed, the work compression ratio is increasing, and the temperature of engine work combustion is getting higher and higher. The existing valve steel has insufficient tensile strength and yield strength at high temperature.

See Table 1 (Figure 11) for high temperature tensile strength and Table 2 (Figure 12) for high temperature yield strength. From the table, we can see that when the exhaust gas temperature of the engine is as high as 800 °C, only the high-temperature nickel-based alloys CH4751 and GH4080A can maintain the continuous strength. Nickel is a rare metal with limited global reserves and the price is as high as several hundred thousand tons. There is a small amount of use in premium sports cars and racing cars. Valve steel has encountered bottlenecks in the selection and development of materials, which greatly limits the further improvement of engine performance.

For the limitation of the strength of the steel for exhaust valves under high temperature use, a technology that can reduce the temperature of the exhaust valve during engine operation, that is, the air-filled sodium valve has emerged. Figure 8 is an air-core-filled sodium air-core valve. The air-core valve is manufactured by machining the disk and the stem into hollow, and then filling the metal with sodium (the physical properties of the metal sodium are heated to Celsius). When it is more than 90 degrees, it will be gasified. When the exhaust valve is working at high temperature, the metal sodium is vaporized, so that a part of the heat is taken away, which reduces the heating condition of the entire valve. High valve high temperature performance (can reduce valve operating temperature of 100 ° C). However, there are many shortcomings in the air-filled sodium valve. One of them: metal sodium has certain dangers during storage, transportation and use. The chemical reactivity of sodium is very high, and it will burn in oxygen, chlorine, fluorine and bromine vapor. In case of water or moisture, it will produce a chemical reaction, generate hydrogen gas, generate a large amount of heat, cause burning or explosion, and metal sodium can spontaneously ignite and explode when exposed to the air. Secondly, the manufacturing process of the air-core valve is quite complicated. It must separate the valve into two separate parts of the disk and the rod, and then drill the hole at the rod end of the disk. The hole diameter is generally 3mm and the depth is 60mm. Small deep holes, in addition to the need for expensive dedicated deep hole drills, low processing efficiency and high cost of consumables (because of deep holes, difficult chip removal, the drill bit is easy to break). After processing the small deep hole, it is difficult to clean, and then the metal sodium is filled (the danger has been introduced in the foregoing). Then, the two separate parts of the disk and the rod are friction welded together, and then the welding boring is performed, and then the heat treatment is eliminated. Welding stress, and finally the two parts of the joint are machined (eliminating different hearts) and then flow into the normal valve processing. It can be seen that the hollow core-filled sodium valve is complicated in processing, high in cost, low in efficiency, and high in scrap rate. Third: Because the disc and the rod are connected together by friction welding. In order to ensure the welding quality, the joint area after welding has a certain guarantee, which restricts the air core area of the valve stem to not be too large (the general rod diameter is 6mm, the aperture is 3mm, accounting for 33% of the valve stem area), even though In this way, the friction welding part is still a high point of quality hazard, and the failure occurs when the fracture occurs. Because the hollow core area is small, the sodium filling is also limited. According to the actual use data, the air core filling sodium valve can only be reduced by 100 °C. , limits the use of air-core valves. With the implementation of energy saving and emission reduction, further improving the combustion efficiency of the engine and increasing the compression ratio are the only effective ways. However, its direct result is that the combustion temperature is higher, the exhaust gas discharge temperature is also higher, and the air-core-filled sodium valve is incapable of being limited by the temperature drop.

The method used to make the valve ensure the normal operation of the exhaust valve at the higher operating temperature of the engine is one of the many problems encountered in the current engine to improve combustion efficiency, increase power output, and save energy and reduce emissions.

Summary of the invention

The object of the present invention is to solve the problem of reliability of normal and continuous operation of a valve in a harsh environment of an engine.

The technical solution adopted for achieving the object of the present invention is such that an engine valve with a heat insulating sleeve to prevent high temperature failure is characterized in that it comprises an engine valve body and a heat insulating sleeve.

The engine valve body is composed of a valve stem and a disk portion.

The insulating sleeve is nested on the valve stem. One end of the heat insulating sleeve faces the disk portion.

Further, the inside of the heat insulating sleeve is a stepped hole. The stepped hole is composed of a small hole and a large hole. The inner wall of the orifice is in contact with the valve stem. There is a gap between the large hole and the valve stem.

Further, the inside of the heat insulating sleeve is a through hole. A section of the heat insulating sleeve adjacent to the disk portion is in contact with the disk neck of the valve, and a gap is left between the heat insulating sleeve away from the disk portion and the valve stem.

Further, the diameter of the valve stem at the gap is reduced.

Further, the small hole is in sliding engagement with the valve stem (101).

Further, the heat insulating sleeve is fixed to the valve body by welding.

Further, the transition portion of the valve stem and the disk portion is a disk neck portion.

The disk portion has an annular land. The annular table surrounds the neck of the disk.

One end of the heat insulating sleeve facing the disk portion is welded to the annular land.

Further, the heat insulating sleeve is integrally formed with the valve stem. A section of the heat insulating sleeve adjacent to the disk portion is integrally connected with the valve stem, and a gap between the heat insulating sleeve away from the disk portion and the valve stem is left.

It is worth noting that Figures 9 and 10 are valve hazardous areas and temperature profiles. It can be seen from Fig. 9 that when the fuel combustion in the combustion chamber is completed, the exhaust valve is opened, and the high-temperature exhaust gas is directly sprayed along the valve, directly flushing the disk neck region C of the valve, which is a typical automobile exhaust valve danger zone and temperature. Distribution state diagram. See Figure 10, we can see from the figure that the maximum temperature of the exhaust valve C area of the V-8 car reaches 732 ° C, (the highest temperature zone is the weak area of the smaller diameter of the rod) and the lowest part of the exhaust valve disc The temperature difference is 149 ° C compared to 583 ° C. More seriously, we can see from Figure 10 that there is a gradually narrowing zone X in the neck of the exhaust valve disc. According to the principle of heat conduction, the high temperature zone will transfer heat to the low temperature zone, so that the highest heated zone C of the disk neck shown in Fig. 10 will transfer a large amount of heat to the lower temperature pole, and the problem arises when the exhaust valve is large. When the heat stored in the diameter C region is conducted to a small diameter, there is a heat transfer difference due to the difference in diameter, thereby forming a heat accumulation region in the X region. With the experience of the inventor of the patent for decades of valve manufacturing, the position of the exhaust valve failure fracture is concentrated in the C zone. In summary, there are two main reasons for exhaust valve failure: 1 high temperature scouring (main cause) Figure 13 steel model is 53cr21mn9Ni4N (referred to as 21-4N) exhaust valve before use metallographic structure map, Figure 14 (with the attached drawing 13 used The same 21-4N material) is the metallographic structure of the high temperature wash. From the comparison of Fig. 13 and Fig. 14, we can see that although a very advanced steel for the exhaust valve 53cr21mn9Ni4N has been selected. However, at high temperatures, the grain boundary of the metal has been severely corroded, and the layered fold has reached level 4, and the performance has been greatly reduced. 2 The heat transfer is unreasonable, and the X zone has a hot accumulation zone, which increases the metal heat loss in the zone.

In view of the above, preferably, the area protected by the heat insulating sleeve is a range surrounded by the gap. The gap has a length h, h is greater than the valve lift. Further, the area protected by the heat shield is the area where the high temperature exhaust gas of the engine is concentrated to flush the valve. The invention adopts an insulation sleeve on the neck of the exhaust valve disc to directly prevent the high temperature exhaust gas from scouring the neck body of the exhaust valve disc, and in particular, effectively protects the concentrated C area from being cleaned, and protects it. The principle is as follows, the inner diameter dimension of the heat insulating sleeve is designed to be larger than the outer diameter of the exhaust valve disc and the rod portion. In this way, although the engine insulation sleeve is heated by the high-temperature exhaust gas, the heat insulation sleeve is heated and then transferred to the exhaust valve stem portion, but the change has been made in essence, and the original ordinary exhaust valve disc neck is directly discharged by the high-temperature exhaust gas. The heat-insulating sleeve on the neck of the exhaust valve disc is washed by the high-temperature exhaust gas and directly protects the neck body of the valve disc. The heat of the insulating sleeve of the exhaust valve disc neck is converted into heat radiation to the valve disc neck to the valve disc portion and the rod portion. It can be seen that the thermal flushing of the neck of the exhaust valve disc changes from concentrated to dispersed, and is converted from heat to heat by direct heat conduction. The principle of heat transfer is that the heat transfer efficiency is greater than the heat radiation efficiency. Therefore, the exhaust valve with a heat insulating sleeve can greatly reduce the heat receiving amount than the ordinary exhaust valve, thereby improving the thermal performance of the exhaust valve in use. It can be seen from the above analysis that the exhaust valve with insulated sleeve clearly blocks the direct erosion of the high temperature exhaust gas to the disk neck of the exhaust valve, and the heat absorbed by the heat insulating sleeve in the high temperature exhaust gas flow is along the heat insulation. The sleeve flows toward the neck of the exhaust valve disc, and part of the heat received by the disc neck is transferred through the engine block, and the other part flows along the exhaust valve stem until the working position of the exhaust valve stem and the valve guide. Cooling through the valve guide. However, the heat absorbed by the normal exhaust valve by the high-temperature exhaust gas flow can only transmit heat along the flow of the rod, but since the hot flush is hit in the high temperature zone C, when the heat stored in the C zone is to be transmitted below the stem, Because the neck diameter of the exhaust valve disc is larger than the diameter of the exhaust valve stem, the heat is crowded and blocked during the transfer process, and heat accumulation occurs. In addition, under the rod, it is also heated by the high-temperature airflow during the work, and the exhaust valve The temperature difference between the neck and the neck is not large, which directly affects the heat transfer speed. Therefore, the excessive area of the neck and the stem of the exhaust door directly shows what I call smoldering. (The above-mentioned common exhaust valve fails to break. Focus on this point), It has been proved that the insulated door exhaust valve can completely solve this problem.

The protection points of the exhaust valve with insulated jacket of the present invention are as follows:

1. After the invention relates to any method using a heat insulating sleeve to achieve the purpose of preventing high temperature failure of the valve.

2. In the prior art, various types of exhaust valves are added to the heat-insulating sleeve, thereby reducing the heat-receiving condition of the exhaust valve and improving the use effect of the exhaust valve at a high temperature.

3. Shape design and extension design of the insulation sleeve.

4. The process of connecting and processing the heat insulation sleeve and the exhaust valve.

5. The high temperature performance of the exhaust valve is improved by the increase of the heat insulation sleeve, the requirement for the heat strength of the raw material is reduced, the valve length is shortened, and the valve stem diameter is reduced (because the strength is increased, the valve design can be reduced)

6. Optimization of the engine block after the valve size and length design changes (the valve length is now reduced by 5-10 mm, so that the cylinder is thinned by 5-10 mm).

7. The heat insulating sleeve of the present invention has a related design improvement scheme of the engine and the engine component and a supporting improvement scheme related to the heat insulating sleeve.

Application of the invention:

With the addition of insulation sleeves, the direct insulation of the high-temperature exhaust gas flow to the neck of the valve disc is directly eliminated, and its invention design is two ways than the original valve production technology for high temperature (1) High temperature resistance. 2. The air core is filled with sodium to cool the heated body that is washed by high temperature. Instead, the valve is protected directly from the source. It effectively improves the performance of the exhaust valve at high temperatures, so it can work more effectively under the current turbocharged engine operating conditions with the best combustion efficiency and the highest exhaust gas discharge temperature. It is a complete replacement for the air-filled sodium exhaust valve that is currently adapted for turbocharged engines. At the same time, it should be pointed out that the current exhaust valve with insulating sleeve is compared with the air-filled sodium exhaust valve, regardless of processing complexity, quality stability, manufacturing cost, safety and scrapping after product failure (since air-filled sodium valve) The sodium in the water will burn with water) has an incomparable advantage. In addition to meeting the current performance of all types of engines, the insulated exhaust valve can further meet the new engine that needs to increase the compression ratio and higher combustion temperature, and match the performance of the exhaust valve (special vehicles such as racing cars). except).

The technical effect of the invention is undoubted, the heat-insulating valve can significantly reduce the heating state of the exhaust valve under the high-temperature exhaust gas scouring, significantly improve the quality of the valve, and has the reliability of normal continuous operation under the harsh environment of the engine. Existing valves, regardless of Increased to a new height in high temperature or service life. The process is simple and feasible, the production cost is low, and the quality and price advantage. This is a new generation of engine development and development, providing a better choice and technical support for the special requirements of the exhaust valve.

DRAWINGS

Figure 1 is a schematic view of the structure of the present invention (stepped insulation sleeve);

Figure 2 is a schematic view of the structure of the present invention (with a straight-through heat insulation sleeve, and the valve stem has a thin neck);

Figure 3 is a schematic view of the structure of the present invention (excluding the heat insulating sleeve);

Figure 4 is a schematic view of the structure of the present invention (excluding the heat insulating sleeve, the valve stem has a thin neck);

Figure 5 is a schematic structural view of a stepped heat insulation sleeve;

Figure 6 is a schematic structural view of a straight-through heat insulating sleeve;

Figure 7 is a schematic view of a conventional valve;

Figure 8 is a schematic diagram of the air-filled sodium valve

Figure 9 is a map of the danger zone when the valve is working.

Figure 10 is the temperature distribution diagram when the valve is working.

Figure 11 is a high temperature tensile strength table in GB/T 12773-2008 steel and alloy rods for internal combustion engine valves;

Figure 12 is a table of high temperature yield strength in GB/T 12773-2008 steel and alloy rods for internal combustion engine valves;

Figure 13 is a metallographic test report (no valve used);

Figure 14 shows the metallographic test report (valve has been used).

In the figure: valve stem 1, disk neck 101, heat insulation sleeve 2, step insulation sleeve 2a, straight-through heat insulation sleeve 2b, welded portion 23, small hole 201, large hole 202, disk portion 3, annular table 301 The disk top 4, the exhaust impingement portion 5, the valve stem working portion 6, the tail portion 7, and the hardened portion 8 in the conduit.

detailed description

The invention is further illustrated by the following examples, but it should not be understood that the scope of the invention described above is limited to the following examples. Various changes and modifications may be made without departing from the spirit and scope of the invention.

The following several embodiments further disclose the specific design and manufacture of the novel valve Method and other content:

Example 1:

An engine valve with a heat shield to prevent high temperature failure, including an engine valve body and a heat insulating sleeve 2.

Referring to FIG. 3 or 4, the engine valve body is composed of a valve stem 1 and a disk portion 3.

Referring to Figure 1 or 2, the insulating sleeve 2 is nested on the valve stem 1. One end of the heat insulating sleeve 2 faces the disk portion 3, and the other end faces the small end of the valve stem 1.

Example 2:

The main structure of this embodiment is the same as that of Embodiment 1. Preferably, referring to Figures 1 and 5, the inside of the heat insulating sleeve 2 is a stepped hole, that is, the stepped heat insulating sleeve 2a shown in Fig. 5. The stepped hole is composed of a small hole 201 and a large hole 202. The inner wall of the small hole 201 is in contact with the valve stem 1. There is a gap between the large hole 202 and the valve stem 1.

Example 3:

The main structure of this embodiment is the same as that of Embodiment 1. Preferably, referring to FIG. 6, the inside of the heat insulation cover 2 is a through hole, that is, a straight-through heat insulation cover 2b shown in FIG. The heat insulating sleeve 2 is in close proximity to a portion of the disk portion 3 adjacent to the disk portion 3, and a gap is left between the portion of the heat insulating sleeve 2 remote from the disk portion 3 and the valve stem 1.

Example 4:

The main structure of this embodiment is the same as that of Embodiment 3. Referring to Figures 2 and 4, the diameter of the valve stem 1 at the gap is reduced. That is, the valve stem 1 has a thin neck portion, so that the gap between the heat insulating sleeve 2 and the valve stem 1 becomes large.

Example 5:

The main structure of the embodiment is the same as that of the embodiment 2. Preferably, the small hole 201 is in sliding engagement with the valve stem 1 (the matching clearance is subject to sliding).

Example 6

The main structure of this embodiment is the same as that of Embodiment 3. Preferably, the small hole 201 is slidably engaged with the valve stem 1 (the matching clearance is subject to sliding).

Example 7

The main structure of this embodiment is the same as that of the

embodiment

1, 5 or 6, and preferably, the heat insulating sleeve 2 is welded to the valve body welding portion 23 by welding.

Example 8

The main structure of this embodiment is the same as that of Embodiment 7, and preferably, the valve stem 1 and the disk portion 3 The transition portion is the disk neck 101.

The disk portion 3 has an annular land 301. The annular land 301 surrounds the disk neck 101.

One end of the heat insulating cover 2 facing the disk portion 3 is welded to the annular land 301, that is, the welded portion 23 is formed.

Example 9

The main structure of this embodiment is the same as that of the

embodiment

1, 2 or 3. Generally, for a valve having a large diameter, the heat insulating sleeve 2 can be integrally formed with the valve stem 1. That is, a section of the heat insulating sleeve 2 adjacent to the disk portion 3 is integrally connected with the valve stem 1, and a gap between the section of the heat insulating sleeve 2 remote from the disk portion 3 and the valve stem 1 is left. That is, by turning (or other means), an annular groove is formed between the originally integrated heat insulating sleeve 2 and the valve stem 1, and the annular groove is a gap between the heat insulating sleeve 2 and the valve stem 1.

Example 10:

The shape design principle is as follows: the temperature difference between the inside and outside of the material should be reduced.

a. Minimize the difference between the outer diameter and the inner diameter of the heat insulating sleeve, that is, to form a thin wall.

b. However, in practical applications, the welding strength of the insulating sleeve and the neck of the exhaust valve should be ensured. The welded part must have sufficient thickness to be welded in the welding process. The thickness of the welded part of the insulating sleeve should be thicker than other. The thin wall of the part has increased. See Figure 3 for the insulation cover design. From the design drawing 3, we can see that the insulation cover is an inner stepped sleeve shape.

Example 11

The main structure of this embodiment is the same as that of the

embodiment

2, 3 or 9. Preferably, the area protected by the heat insulating cover 2 is a range surrounded by the gap. The gap has a length h, h is greater than the valve lift.

Further, the area protected by the heat insulating jacket 2 is an area where the high temperature exhaust gas of the engine is concentrated to flush the valve, that is, the c area.

Insulation sleeve design: Because the valve insulation sleeve is subjected to frequent high-temperature airflow, the high temperature resistance, fast heat dissipation and no deformation are the design priorities. The selected materials should have the following conditions: a. High temperature resistant material. b, the material thermal conductivity should be large. C, the coefficient of thermal expansion is small.

Example 12

Other design requirements for insulation sleeves: According to the absorption and propagation of heat by objects, it is related to the quality of the surface of the objects. The inner and outer surfaces of the insulation sleeve should be processed to meet the quality requirements.

Example 13

This embodiment is a manufacturing method of the valve disclosed in Embodiment 7:

a, according to the normal process of the valve to the semi-finished products.

b. A step is formed in the neck of the valve disc (ie, an annular table as a welding groove). c. Unloading a special insulation guide sleeve for the exhaust valve.

d. The guide sleeve is placed in the neck step of the exhaust valve disc, and the heat insulation sleeve and the exhaust valve are welded together by welding (other manners may also be used).

e. Modify the welded part and heat treatment. f. Transfer the valve to the subsequent processing flow to the finished product.

Example 14

This embodiment is designed for the size of the insulation sleeve:

The length of the thin sleeve of the insulating sleeve should be designed to be a few millimeters above the C area where the engine's high temperature exhaust gas is concentrated. The insulation sleeve at the C area is designed to be thin-walled because it can effectively reduce the amount of heat absorption in the C area, thereby weakening the heat radiation quality of the insulation sleeve to the neck body of the exhaust valve, while the heat insulation sleeve itself In terms of thin wall area, heat is more easily transferred to the thick area. The faster the heat dissipation, the smaller the amount of heat radiation that the valve body receives.

As the valve increases the heat insulation sleeve, the overall weight of the valve will increase, which increases the inertia of the valve during high-speed movement, and also increases the impact damage of the valve sealing cone surface and the cylinder seat ring, which is contrary to the valve design. Lightweight principle.

However, in this embodiment, the heat insulating sleeve is designed to be thin and light in weight. At the same time, the increased heat insulation sleeve improves the heating condition of the valve body and greatly improves the material strength. Therefore, under the same load conditions, the valve stem diameter can be reduced, and the weight reduction effect is achieved. It should also be pointed out here that the original valve design takes into account that the valve neck will expand after being heated, which directly affects the movement of the valve stem up and down in the conduit. Therefore, in the original valve design, in order to ensure the normal operation of the valve in the conduit, the distance from the valve disc portion to the conduit opening is increased to achieve a gradual heat dissipation effect. This embodiment of the invention effectively reduces the heating condition of the disk and the stem, so that the distance from the valve disc portion to the conduit opening can be correspondingly reduced. Both the valve weight reduction effect and the overall design of the engine block can be reduced, the weight is reduced, and the economic benefit is increased.

Claims

An engine valve with a heat insulation sleeve for preventing high temperature failure, comprising: an engine valve body and a heat insulation sleeve (2);

The engine valve body is composed of a valve stem (1) and a disk portion (3);

The insulating sleeve (2) is nested on the valve stem (1); one end of the insulating sleeve (2) faces the disk portion (3).
The engine valve for preventing high temperature failure with a heat insulating sleeve according to claim 1, wherein the heat insulating sleeve (2) has a stepped hole inside; the stepped hole is made up of a small hole (201) and a large hole The hole (202) is composed; the inner wall of the small hole (201) is in contact with the valve stem (1); and there is a gap between the large hole (202) and the valve stem (1).
The engine valve for preventing high temperature failure according to claim 1, wherein the heat insulating sleeve (2) has a through hole inside; the heat insulating sleeve (2) is close to the disk portion. A section of (3) is in contact with the disk neck of the valve, and a gap is left between the section of the heat insulating sleeve (2) remote from the disk portion (3) and the valve stem (1).
An engine valve with a heat insulating sleeve for preventing high temperature failure according to claim 3, characterized in that the diameter of the valve stem (1) at the gap is reduced.
An engine valve with a heat insulating sleeve for preventing high temperature failure according to claim 2 or 3, characterized in that the small hole (201) is in sliding engagement with the valve stem (1).
An engine valve for preventing high temperature failure with a heat insulating sleeve according to claim 1, 2 or 3, characterized in that the heat insulating sleeve (2) is fixed to the valve body by welding.
The engine valve for preventing high temperature failure according to claim 6, wherein the transition portion of the valve stem (1) and the disk portion (3) is a disk neck portion (101);

The disk portion (3) has an annular land (301); the annular table (301) surrounds the disk neck (101);

One end of the heat insulating sleeve (2) facing the disk portion (3) is welded to the annular land (301).
The engine valve for preventing high temperature failure with a heat insulating sleeve according to claim 1, 2 or 3, characterized in that: the heat insulating sleeve (2) is integrally formed with the valve stem (1); A sleeve (2) adjacent to the disk portion (3) is integrally connected with the valve stem (1), and the heat insulating sleeve (2) is separated from a portion of the disk portion (3) and the valve stem (1). There is a gap.
An engine valve for preventing high temperature failure with a heat insulating sleeve according to claim 2, 3 or 8, wherein the area protected by the heat insulating sleeve (2) is a range surrounded by the gap; The length of the gap is h, h is greater than the valve lift.
The engine valve for preventing high temperature failure with a heat insulating sleeve according to claim 9, wherein the area protected by the heat insulating jacket (2) is an area where the high temperature exhaust gas of the engine is concentrated to flush the valve.