Steel piston with composite welded structure

Abstract

The utility model relates to a steel piston with composite welding structure, including the piston main part that has the combustion chamber with inside setting inner chamber in top, the piston main part is composed of first piston subassembly and second piston subassembly, and first piston subassembly and second piston subassembly are fixedly connected through first connecting place and second connecting place, and form the closed cooling oil channel in the inside, first connecting place is arranged between the radial wall thickness area of cooling oil channel inner side and piston inner chamber, or is arranged between the wall thickness area of combustion chamber surface and cooling oil channel inner side and is with piston main part axis angle 40~50 degrees, or is arranged between the axial wall thickness area of piston top surface and cooling oil channel, second connecting place is arranged between the radial wall thickness area of cooling oil channel outer side and the outer circular surface of piston main part, the utility model through reasonable arrangement weld position, avoids piston top surface and combustion chamber high load area, reduces the influence of welding flash or welding defect to cooling oil flow, improves the cooling efficiency.

Description

Technical Field

[0001] This utility model relates to the field of engine piston technology, and specifically to a steel piston with a composite welded structure. Background Technology

[0002] In the field of internal combustion engines, steel pistons have become an important direction in piston development and are widely used due to their superior performance and reliability. To reduce the temperature of the piston head, cooling oil channels are provided in the piston head. Currently, laser welding, electron beam welding, and friction welding are the main processes for forming closed cooling channels.

[0003] The existing steel piston cooling oil passages only use one connection method, and there are certain problems in the application process: 1. Friction welding inevitably produces flash in the cooling channel. This flash may prevent the cooling oil from reaching the top of the cooling channel, thus affecting the cooling effect of the piston head.

[0004] 2. Welds formed by laser welding and electron beam welding processes are typically located in high-temperature, high-pressure, and high-load areas such as the piston top surface or the combustion chamber. Because the weld is a closed ring, the overlapping area between its start and end points is prone to welding defects. These defects significantly reduce weld quality, thereby affecting piston performance and engine safe operation, and shortening the service life of the piston and engine.

[0005] The weld arrangement failed to effectively avoid high-load areas, and the presence of welding defects adversely affected piston quality and engine operating safety. Utility Model Content

[0006] To address the shortcomings of existing technologies, this utility model provides a steel piston with a composite welded structure. By optimizing the weld arrangement, the welds are made to avoid high-load areas such as the piston top surface and combustion chamber, reducing the impact of friction welding flash or defects from laser welding and electron beam welding on the flow of cooling oil and piston quality, thereby improving the safety and reliability of piston and engine operation.

[0007] This utility model is achieved through the following technical solution: A steel piston with a composite welded structure is provided, including a piston body with a combustion chamber at the top and an internal cavity. The piston body is composed of a first piston assembly and a second piston assembly. The first piston assembly and the second piston assembly are fixedly connected by a first connection and a second connection, and form a closed cooling oil passage inside. The first connection is located in the radial wall thickness region between the inner side of the cooling oil passage and the inner cavity of the piston; or in the wall thickness region between the surface of the combustion chamber and the inner side of the cooling oil passage and at an angle of 40~50° with the piston body axis; or in the axial wall thickness region between the top surface of the piston body and the cooling oil passage. The second connection is located in the radial wall thickness region between the outer side of the cooling oil passage and the outer circular surface of the piston body.

[0008] Furthermore, the first connection point is connected using friction welding.

[0009] As one embodiment of this utility model, the second connection is made by any one of laser welding, electron beam welding, argon arc welding or carbon dioxide shielded welding.

[0010] In another embodiment of this utility model, the second connection is not welded, and the first piston assembly and the second piston assembly are tightly fitted at this point by an interference fit, with an interference amount of 0.02-0.08mm.

[0011] Furthermore, a coarse groove extending along the circumference is formed on the outer circular surface of the piston body, and the second connection is located in the radial wall thickness region between the bottom of the coarse groove and the outer side of the cooling oil passage.

[0012] Preferably, the first piston assembly is a piston assembly made of 38MnVS6, 42CrMoA or 42CrMo4 ultra-high strength alloy steel.

[0013] Preferably, the second piston assembly is a piston assembly made of 38MnVS6, 42CrMoA, 42CrMo4, 20CrNiMo or 20CrNi3MoTi steel.

[0014] The beneficial effects of this utility model are: This invention relates to a steel piston with only one friction weld, which reduces the number of friction welds compared to forged steel pistons using a single friction weld connection process. This reduces the impact of friction weld flash on the cooling oil and improves the cooling effect of the piston head. Simultaneously, the second connection uses laser welding, electron beam welding, argon arc welding, or CO2 shielded welding to avoid high-load areas such as the piston top surface and combustion chamber, reducing the impact of welding defects present in fusion welding on piston quality. Through this composite welding process, the risk of quality defects associated with traditional single welding processes is reduced, significantly improving the safety and reliability of the piston and engine operation, and extending their service life. Simulation analysis shows that changing the outer weld from friction welding to fusion welding effectively avoids the impact of flash on oil flow, reducing the piston fire land temperature by 5-10°C. Furthermore, when the fusion weld is located in the area from the outer circumference of the piston to the outer side of the inner cooling oil passage, no cases of weld cracking failure have been observed.

[0015] This invention is applicable to medium and heavy-duty diesel or natural gas engines. By optimizing the weld arrangement, the welds avoid high-load areas such as the piston top surface and combustion chamber, reducing the impact of friction welding flash, laser welding, or electron beam welding defects on cooling oil flow and piston quality, thereby improving the safety and reliability of the piston and engine operation. The innovations in structural design and welding process provide a more reliable technical solution for the manufacture of internal combustion engine pistons. Attached Figure Description

[0016] Figure 1 This is a partial structural cross-sectional schematic diagram of Embodiment 1 of this utility model.

[0017] Figure 2 This is a partial structural cross-sectional schematic diagram of Embodiment 2 of this utility model.

[0018] Figure 3 This is a partial structural cross-sectional schematic diagram of Embodiment 3 of this utility model.

[0019] Figure 4 This is a partial structural cross-sectional schematic diagram of Embodiment 4 of this utility model.

[0020] As shown in the figure: 10 First piston assembly, 11 Second piston assembly, 12 Combustion chamber, 13 Cooling oil passage, 13a Outer side of cooling oil passage, 13b Inner side of cooling oil passage, 14 Top surface, 15 Inner cavity, 16 Outer circular surface, 18 Rough groove, 21a, 21b, 21c, 21d First connection points, 22a, 22b, 22c, 22d Second connection points. Detailed Implementation

[0021] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0022] Example 1: like Figure 1As shown, a steel piston with a composite welded structure includes a piston body with a combustion chamber 12 at the top and an internal cavity 15. The piston body is composed of a first piston assembly 10 and a second piston assembly 11, which are fixedly connected by a first connection and a second connection, forming a sealed cooling oil passage 13 inside. The first piston assembly 10, as the main part of the piston body, also has a portion of the combustion chamber 12 and the cooling oil passage 13, and is made of ultra-high strength alloy steel such as 38MnVS6, 42CrMoA, or 42CrMo4 to improve its strength. The second piston assembly 11 has a portion of the cooling oil passage 13, which mainly forms the outer circumference of the piston, and is made of ultra-high strength alloy steel such as 38MnVS6, 42CrMoA, or 42CrMo4, or may also be made of lower strength steel with higher processing performance such as 20CrNiMo or 20CrNi3MoTi.

[0023] The first connection 21a is located in the radial wall thickness region between the inner side surface 13b of the cooling oil passage and the inner cavity 15 of the piston; the second connection 22a is located in the radial wall thickness region between the outer side surface 13a of the cooling oil passage and the outer circular surface 16 of the piston body.

[0024] The first connection 21a is connected by friction welding, and the second connection 22a is connected by laser welding.

[0025] In this embodiment, the first connection 21a and the second connection 22a are both radially distributed. After the first piston assembly 10 and the second piston assembly 11 are welded and fixed, the stress distribution is optimized, which is suitable for high explosion pressure diesel engines and has a long service life.

[0026] Example 2: like Figure 2 As shown, its second connection 22b is located at the wall thickness of the coarse groove 18 and the outer side 13a of the cooling oil passage. The difference between this embodiment and embodiment 1 is that: before the first piston assembly 10 and the second piston assembly 11 are connected, a coarse groove 18 is circumferentially opened at the wall thickness of the outer circular surface 16 of the piston body.

[0027] In this embodiment, by opening a coarse groove 18 on the outer peripheral surface 16 of the piston body, the flow of cooling oil is optimized and the weight of the piston body is reduced, making it suitable for high-speed engines.

[0028] Example 3: like Figure 3 As shown, a steel piston with a composite welded structure has a second connection 22c located in the radial wall thickness region between the outer side 13a of the cooling oil passage and the outer circular surface 16 of the piston body. The difference from Embodiment 1 is that the first connection 21c is located in the wall thickness region between the surface of the combustion chamber 12 and the inner side 13b of the cooling oil passage and forms a 45° angle with the piston body axis.

[0029] By tilting the first connection 21c, the strength around the combustion chamber 12 is increased, making it suitable for high-performance engines and reducing the tendency for knocking.

[0030] Example 4: like Figure 4 As shown, a steel piston with a composite welded structure has a second connection 22d located in the radial wall thickness region between the outer side 13a of the cooling oil passage and the outer circular surface 16 of the piston body. The difference from Embodiment 1 is that the first connection 21d is located in the axial wall thickness region between the top surface 14 of the piston body and the cooling oil passage 13.

[0031] The first connection 21d is axially arranged, which allows the thermal deformation of the top surface 14 of the piston body to be controlled, making it suitable for high heat load conditions and improving temperature uniformity.

[0032] Example 5: A steel piston with a composite welded structure has a first connection point connected by friction welding; the second connection point 22a is not welded, and the first piston assembly 10 and the second piston assembly 11 are tightly fitted at this point by interference fit, with an interference amount of 0.02mm.

[0033] Of course, the above description is not limited to the examples above. Technical features of this utility model not described can be implemented by or using existing technology, and will not be repeated here. The above embodiments and drawings are only used to illustrate the technical solution of this utility model and are not intended to limit this utility model. This utility model has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this utility model do not depart from the spirit of this utility model and should also fall within the protection scope of the claims of this utility model.

Claims

1. A steel piston with a composite welded structure, comprising a piston body having a combustion chamber (12) at the top and an inner cavity (15) inside, the piston body being composed of a first piston assembly (10) and a second piston assembly (11), characterized in that: The first piston assembly (10) and the second piston assembly (11) are fixedly connected through the first connection and the second connection, and form a closed cooling oil passage (13) inside; The first connection is located in the radial wall thickness region between the inner side (13b) of the cooling oil passage and the inner cavity (15) of the piston; or in the wall thickness region between the surface of the combustion chamber (12) and the inner side (13b) of the cooling oil passage and at an angle of 40~50° with the piston body axis; or in the axial wall thickness region between the top surface (14) of the piston body and the cooling oil passage (13). The second connection is located in the radial wall thickness region between the outer side of the cooling oil passage (13a) and the outer circular surface (16) of the piston body.

2. The steel piston with a composite welded structure according to claim 1, characterized in that: The first connection is made by friction welding.

3. The steel piston with a composite welded structure according to claim 2, characterized in that: The second connection is made using any one of the following methods: laser welding, electron beam welding, argon arc welding, or carbon dioxide shielded welding.

4. The steel piston with a composite welded structure according to claim 2, characterized in that: The second connection is not welded. The first piston assembly (10) and the second piston assembly (11) are tightly fitted at this point by an interference fit, with an interference amount of 0.02-0.08 mm.

5. The steel piston with a composite welded structure according to claim 1, characterized in that: The outer circular surface (16) of the piston body has a coarse groove (18) extending along its circumference, and the second connection is located in the radial wall thickness region between the bottom of the coarse groove (18) and the outer side (13a) of the cooling oil passage.

6. The steel piston with a composite welded structure according to claim 1, characterized in that: The first piston assembly (10) is a piston assembly made of 38MnVS6, 42CrMoA or 42CrMo4 ultra-high strength alloy steel.

7. The steel piston with a composite welded structure according to claim 1, characterized in that: The second piston assembly (11) is a piston assembly made of 38MnVS6, 42CrMoA, 42CrMo4, 20CrNiMo or 20CrNi3MoTi steel.

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