Valve for internal combustion engine using gaseous fuel

Abstract

The valve of the internal combustion engine using gas fuel comprises a disc part and a rod part extending upward from the top end of the disc part, wherein the disc part is integrally forged by iron and / or nickel-based alloy material, and comprises a disc end face, an outer circumferential face extending upward around the disc end face, a disc conical face extending upward from the outer circumferential face, and a disc back face extending from the disc conical face to the rod part; a roll-hardened layer with a thickness of greater than or equal to 1.2 mm is directly formed on the forged disc conical face; a transition connecting arc face with a radius R is formed between the outer circumferential face of the disc part and the disc conical face; the extension height of the outer circumferential face is H; and R / H is greater than or equal to 0.2.

Description

Technical Field

[0001] This utility model generally relates to valves for internal combustion engines, and more specifically, to valves for internal combustion engines using gaseous fuels. Background Technology

[0002] More and more new fuel engines are being developed and put into use. These new fuels share common characteristics: low carbon emissions, high combustion temperatures, and more complete combustion. High combustion temperature is a necessary condition for achieving emission reduction. Taking hydrogen and natural gas as examples, compared to fuel combustion, these gaseous fuels, in addition to their high combustion temperatures, are also highly corrosive, making valve discs extremely prone to ablation and damage. Engine valves, especially exhaust valves, are subjected to high-temperature environments and thermal shock for extended periods. When alloy materials are welded onto the valve discs, the thousands of tensile-compressive stress changes per minute during valve operation can easily cause the welded alloy material to crack or even detach. If no alloy material is welded onto the valve discs, the hardness is low and wear resistance is poor. Even with upgraded materials, such as expensive high-nickel alloys, the hardness improvement is very limited and significantly increases costs.

[0003] In addition, conventional valve designs where the disc cone surface forms an angle with the outer circumference surface, especially exhaust valves used in such harsher environments, become more fragile and prone to failure due to friction, material thermal fatigue, and oxidation. The angled area has a high stress concentration, heat easily accumulates there, exacerbating thermal stress, and is subject to the combined action of tensile and shear stresses, which can easily form a high-stress zone, leading to crack initiation and becoming a failure point. Utility Model Content

[0004] The purpose of this invention is to provide a valve for an internal combustion engine that uses gaseous fuel, which can reliably adapt to the high temperature and high corrosion environment of such an engine.

[0005] According to this utility model, a valve for an internal combustion engine using gaseous fuel is provided, comprising a disc portion and a rod portion extending upward from the top of the disc portion. The disc portion is integrally forged from iron and / or nickel-based alloy material and includes a disc end face, an outer circumferential surface extending upward around the disc end face, a disc conical surface extending obliquely upward from the outer circumferential surface, and a disc back face extending from the disc conical surface to the rod portion. A roll-hardened layer with a thickness ≥1.2mm is directly formed on the forged disc conical surface, and a transition connecting arc surface with a radius of R is formed between the outer circumferential surface of the disc portion and the disc conical surface. The extension height of the outer circumferential surface is H, and R / H≥0.2.

[0006] According to the valve of this invention, the iron and / or nickel-based alloy material is preferably selected from any one of 21-4NWNb, 6Cr21, Ni30, 80A and Waspaloy, and more preferably Ni30.

[0007] According to the valve of this invention, a transitional connecting arc surface can also be formed between the disc end face and the outer circumferential surface of the disc portion. Additionally, a transitional connecting arc surface can also be formed between the disc conical surface and the disc back surface of the disc portion.

[0008] According to the valve of this invention, the thickness (rolling depth) of the rolled hardening layer on the disc cone surface is preferably no more than 1.5 mm.

[0009] According to the valve of this invention, the roll-hardened layer on the disc cone surface is preferably a heat-treated recrystallized layer. This can further improve the valve's durability, especially its wear resistance.

[0010] According to the present invention, the valve disc may be further formed with a metal surface reinforcement layer.

[0011] The valve of this invention is particularly suitable for use as an exhaust valve.

[0012] This invention improves the valve's durability by directly forming a deep roll-hardened layer on the conical surface of the valve disc made of forged iron and / or nickel-based alloys, and by designing the transition connection of the valve disc as an arc surface. This also significantly reduces the manufacturing cost. Attached Figure Description

[0013] Figure 1 A schematic diagram of the structure of valves used in common internal combustion engines; Figure 2 This is a partial cross-sectional schematic diagram of a valve with a disc-cone surface roll-hardened layer according to the present invention; Figure 3 The surface hardness testing area of ​​the cone-shaped rolled hardened layer is shown; Figure 4 This is a schematic diagram of the area for detecting the depth and hardness of the rolled hardened layer on the conical surface. Figure 5 Metallographic image of a simple roll-hardened layer on a conical surface; Figure 6 Metallographic image of the recrystallized layer after heat treatment on the conical surface; Figure 7 A partially enlarged cross-sectional view of the valve disc portion according to the present invention is shown; and Figure 8 for Figure 7 A variation of the valve disc shown. Detailed Implementation

[0014] The present invention will be further described below with reference to the accompanying drawings.

[0015] Figure 1A typical internal combustion engine valve is shown, consisting of a disc portion 10 and a rod portion 20 extending from the side of the disc portion 10 opposite to the disc end face (far left of the diagram). This type of valve is typically formed by forging from iron and / or nickel-based alloys and can be used as an exhaust valve or an intake valve, wherein when used as an exhaust valve, it can also be formed as a hollow sodium-filled valve.

[0016] Figure 2 A partial cross-sectional schematic diagram of a valve with a disc-cone surface roll-hardened layer according to the present invention is shown, wherein a roll-hardened layer 11 of thickness T is directly formed on the disc-cone surface (used as a sealing surface) of the disc portion 10, which is forged from iron and / or nickel-based materials, by deep rolling. T ≥ 1.2 mm to achieve a hardness higher than HV450. Compared with conventional valves, the disc-cone surface portion of the disc portion 10 does not require the additional welding of high-cost wear-resistant alloys. The iron and / or nickel-based material used for forging can be a material with the following elemental composition by mass percentage.

[0017] 21-4NWNb (Austenitic Heat-Resistant Steel 50Cr21Mn9Ni4Nb2WN): C 0.45~0.55; Si≤0.45; Mn8.00~10.00; P ≤0.050; S ≤0.030; Ni 3.50~5.00; Cr 20.00~22.00; Nb 1.80~2.50; W 0.80~1.50; N 0.40~0.60; Cu ≤0.30; Fe balance.

[0018] 6Cr21 (Austenitic heat-resistant steel 61Cr21Mn10Mo1V1Nb1N): C 0.57~0.65; Si≤0.25; Mn 9.50~11.50; P ≤0.050; S ≤0.030; Ni ≤1.50; Cr 20.00~22.00; Nb 1.00~1.20; V 0.75~1.00; Mo 0.75~1.25; N 0.40~0.60; Cu ≤0.30; Fe balance.

[0019] Ni30 (Sanai3015 iron-nickel alloy): C ≤0.08; Si≤0.50; Mn ≤0.50; P ≤0.015; S ≤0.010; Ni 30.00~34.00; Cr 14.00~16.00; Nb 0.45~1.00; Al 1.60~2.20; Ti 2.30~2.90; Mo 0.40~1.00; Cu ≤0.30; B ≤0.010; Fe balance.

[0020] 80A (Nickel-based alloy GH4080A): C 0.04~0.10; Si≤1.00; Mn ≤1.00; P ≤0.020; S ≤0.015; Cr 18.00~21.00; Al 1.00~1.80; Ti 1.80~2.70; Fe ≤3.00; Cu ≤0.20; B ≤0.008; Co ≤2.00; Ni balance.

[0021] Waspaloy (nickel-based alloy): C 0.02~0.10; Si≤0.75; Mn ≤0.50; S ≤0.02; Cr 18.00~21.00; Al 1.20~1.50; Ti 2.75~3.25; Fe ≤2.00; Mo 3.50~5.00; Cu ≤0.10; B 0.003~0.008; Co 12.00~15.00; Zr 0.02~0.12; Ni balance.

[0022] The following examples all use Ni30 (Sanai3015 iron-nickel alloy).

[0023] Figure 3 The surface hardness testing area of ​​the roll-hardened layer on the conical surface is shown. For example... Figure 3 As shown, hardness was measured at points within 0.2 mm from the surface of the disc cone, and compared with the hardened layer formed by cold forging; Table 1 lists the comparative test data.

[0024]

[0025] The data listed in Table 1 show that, compared with the cold forging and patting hardened layer, the average surface hardness of the disc cone surface increases by 65 units after the roll hardening layer is formed, which significantly enhances the wear resistance of the disc cone surface.

[0026] Figure 4 This is a schematic diagram of the test area for the depth and hardness of the hardened layer formed by rolling on the conical surface. Points were taken within a range of 0.2-1.5 mm from the surface of the conical surface to test the hardness, with a spacing of 0.1-0.3 mm between each point. The hardened layer was compared with that formed by cold forging and patting. Table 2 lists the comparative test data.

[0027]

[0028] The data listed in Table 2 show that, compared with the cold forging hardened layer, the average hardness of the material increased by 30 units after the valve disc cone surface was formed with a rolling hardened layer, indicating that the hardening depth of the valve disc cone surface was significantly improved.

[0029] After the roll-hardened layer is formed on the conical surface, it will exhibit a natural "shrinkage" trend, that is, the stress state of the conical surface will stabilize into a compressive stress state. At this time, further transforming the roll-hardened layer 11 of the conical surface into a heat-treated recrystallized layer (e.g., holding at 650℃ for 2 hours) can further improve the hardness. Figure 5 and Figure 6 Metallographic images of the roll-hardened layer 11 (simple roll-hardened layer) and the heat-treated recrystallized layer are shown respectively. It is evident that the grains in the heat-treated recrystallized layer exhibit significant dislocation deformation, resulting in finer grains, which demonstrates a significant improvement in hardness. Table 3 presents comparative experimental data (unit: HV0.5) on the surface hardness of the simple roll-hardened layer and the heat-treated recrystallized layer on the disc-cone surface. The data in Table 3 indicate that if the roll-hardened layer is further transformed into a heat-treated recrystallized layer, the average surface hardness can be increased by nearly 50 units.

[0030]

[0031] Additionally, the valve disc 10 can undergo metal surface hardening (WPC) treatment, which transforms the tensile stress or zero stress in the formed surface and subsurface layers into compressive stress. WPC treatment can be performed using 0.35 mm stainless steel shot at a pressure of 0.55 MPa. After high-speed shot peening, the surface compressive stress value reaches -413 to -515 MPa. When subjected to thermal cyclic strain failure tests simultaneously with products that have not undergone this treatment, the number of thermal cycles before failure is significantly increased, with an increase ranging from 20% to 120%.

[0032] Figure 7 A partially enlarged cross-sectional view of the valve disc 10 of this invention is shown. (See attached image.) Figure 7 As shown, the connection 17 between the outer circumferential surface 15 of the disc 10 and the conical surface 16 is also rounded to form a transitional connecting arc surface, wherein the radius of the arc is R, the extension height of the outer circumferential surface 15 is H, and R / H≥0.2. Compared with the conventional valve's angled design at this connection 17, this transitional connecting arc surface has the following advantages.

[0033] 1. By smoothly dispersing stress, the stress concentration factor is significantly reduced.

[0034] 2. The heat flow is more uniform, avoiding localized heat accumulation. The thermal stress distribution gradient is gentler, and the peak stress is lower than at right angles.

[0035] 3. Extend fatigue life and reduce the risk of hot cracking.

[0036] Figure 8 for Figure 7 A variation of the valve disc 10 shown. For example... Figure 8As shown, in addition to the transition connecting arc surface at the connection point 17 between the outer circumferential surface 15 and the conical surface 16 of the disk portion 10, the above-mentioned arc-forming treatment can also be applied to the connection point 14 between the disk end face 13 and the outer circumferential surface 15 and the connection point 18 between the conical surface 16 and the back surface 19 of the disk to form the corresponding transition connecting arc surface.

[0037] Finally, the valve disc cone surface can be micro-ground to meet the accuracy requirements for its size, roughness, roundness, etc.

[0038] The exhaust valve of this invention eliminates the need for alloy overlay welding on the disc cone surface, thus avoiding problems such as cracking and detachment caused by alloy overlay welding and significantly reducing costs.

Claims

1. A valve for an internal combustion engine using gaseous fuel, comprising a disc portion and a rod portion extending upward from the top of the disc portion, wherein the disc portion is integrally forged from an iron and / or nickel-based alloy material, and includes a disc end face, an outer circumferential surface extending upward around the disc end face, a disc conical surface extending obliquely upward from the outer circumferential surface, and a disc back face extending from the disc conical surface to the rod portion, characterized in that, The forged disc cone surface also has a roll hardening layer with a thickness of ≥1.2mm directly formed, and a transition connecting arc surface with radius R is formed between the outer circumferential surface of the disc and the disc cone surface, with an extension height of H and R / H≥0.

2.

2. The valve of the internal combustion engine using gaseous fuel according to claim 1, characterized in that, The iron and / or nickel-based alloy materials are selected from any one of 21-4NWNb, 6Cr21, Ni30, 80A and Waspaloy.

3. The valve of the internal combustion engine using gaseous fuel according to claim 2, characterized in that, The iron and / or nickel-based alloy material is Ni30.

4. The valve of the internal combustion engine using gaseous fuel according to claim 1, characterized in that, A transitional connecting arc surface is also formed between the end face of the disk and the outer circumference surface.

5. The valve of an internal combustion engine using gaseous fuel according to claim 1 or 4, characterized in that, A transitional arc surface is also formed between the conical surface of the disk and the back surface of the disk.

6. The valve of the internal combustion engine using gaseous fuel according to claim 1, characterized in that, The thickness of the roll-hardened layer on the conical surface shall not exceed 1.5 mm.

7. The valve of an internal combustion engine using gaseous fuel according to claim 1 or 6, characterized in that, The roll-hardened layer on the conical surface is a heat-treated recrystallized layer.

8. The valve of the internal combustion engine using gaseous fuel according to claim 1, characterized in that, It is an exhaust valve.

Images