Combined piston and its wear suppression method

Abstract

This invention provides a combined piston and a wear suppression method. The combined piston includes a piston top and a piston skirt, which are connected by at least one threaded connector. The piston top has a mounting chamber, and one end of the piston skirt is inserted into the mounting chamber, forming a first contact surface with the inner wall of the piston top. A first wear-resistant layer is provided at the first contact surface. By providing a first wear-resistant layer at the first contact surface, the combined piston significantly reduces frictional wear between the piston top and piston skirt during relative movement. This prevents cracks or even damage to the piston top and piston skirt at the first contact surface due to wear, thus avoiding equipment damage and malfunction. This ensures long-term stable operation of the combined piston and significantly reduces maintenance frequency and downtime risk.

Description

Technical Field

[0001] This invention relates to the field of piston wear resistance design technology, specifically to a combined piston and its wear suppression method. Background Technology

[0002] As one of the core moving parts of a diesel engine, the piston must continuously withstand high temperature, high pressure and reciprocating friction loads. Its structural stability and wear resistance directly determine the operating efficiency and service life of the equipment.

[0003] Combined pistons are widely used in marine diesel engines due to their flexible structure and low thermal load. Combined pistons typically use threaded connectors to assemble and fix the piston top and piston skirt.

[0004] As the average effective pressure and maximum combustion pressure of high-performance diesel engines continue to increase, the alternating stress at the piston crown and piston skirt mating surface and the pressure surface of the piston crown and piston skirt connecting bolts increases significantly, resulting in stress concentration, abnormal wear, and fatigue cracks.

[0005] Based on this, the inventors of this application propose a combined piston and a method for inhibiting wear thereon, in order to solve one or more of the above-mentioned technical problems. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the defect of the prior art where the piston crown and piston skirt are severely worn, which affects the service life of the piston, and to provide a combined piston and a method for inhibiting wear thereon.

[0007] The present invention solves the above-mentioned technical problems through the following technical solution: The first aspect of the present invention provides a combined piston, comprising: A piston top and a piston skirt, the piston top and the piston skirt being connected by at least one threaded connector; The piston top has a mounting chamber, and one end of the piston skirt is inserted into the mounting chamber and forms a first contact surface with the inner top wall of the piston top. A first wear-resistant layer is provided at the first contact surface.

[0008] The combined piston provided by the present invention can significantly reduce friction and wear when the piston top and piston skirt move relative to each other by setting a first wear-resistant layer at the first contact surface. This can prevent the piston top and piston skirt from cracking or even being damaged due to wear at the first contact surface, thus avoiding problems such as equipment damage and loss of function. This can ensure the long-term stable operation of the combined piston and greatly reduce its maintenance frequency and downtime risk.

[0009] According to one embodiment of the present invention, the first wear-resistant layer is disposed on the inner top wall of the piston top, and the material of the first wear-resistant layer is adapted to the material of the piston skirt.

[0010] According to one embodiment of the present invention, the piston top is made of a high-temperature alloy, and the piston skirt is made of an aluminum alloy; The first wear-resistant layer is any one of a copper plating layer, a copper alloy layer, and an aluminum alloy layer.

[0011] According to one embodiment of the present invention, the first wear-resistant layer is disposed on the top surface of the piston skirt; The first wear-resistant layer is a reinforced wear-resistant layer formed after the top surface of the piston skirt has been reinforced.

[0012] According to one embodiment of the present invention, the first wear-resistant layer is a lubricant layer, which is disposed on the inner top wall of the piston top and / or the top surface of the piston skirt.

[0013] According to one embodiment of the present invention, the lubricant layer is made of either molybdenum disulfide or graphite.

[0014] According to one embodiment of the present invention, the threaded connector is a bolt, and a pad is provided between the bolt head and the inner wall of the piston skirt; A second contact surface is formed between the pad and the inner wall of the piston skirt, and a second wear-resistant layer is provided at the second contact surface.

[0015] According to one embodiment of the present invention, the second wear-resistant layer is disposed on the piston skirt and / or the pad.

[0016] A second aspect of the present invention also provides a method for suppressing wear on a combined piston, employing the combined piston described above, the suppression method comprising: A first wear-resistant layer is formed by applying a surface treatment process to the first contact surface between the piston top and the piston skirt.

[0017] According to one embodiment of the present invention, the first wear-resistant layer is formed by coating the inner top wall of the piston top with one of copper plating, copper alloy and aluminum alloy materials.

[0018] According to one embodiment of the present invention, the first wear-resistant layer is formed by performing a surface strengthening treatment on the top surface of the piston skirt; wherein the surface strengthening treatment method is one of laser remelting and micro-arc oxidation.

[0019] According to one embodiment of the present invention, a lubricant is applied between the inner top wall of the piston top and the top surface of the piston skirt to form the first wear-resistant layer; wherein the lubricant is either MoS2 or graphite.

[0020] According to one embodiment of the present invention, the piston top and the piston skirt are connected by at least one threaded connector, and a pad is provided in front of the threaded connector and the piston skirt; A second wear-resistant layer is provided on the second contact surface between the pad and the piston skirt. Attached Figure Description

[0021] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, wherein: Figure 1 This is a cross-sectional view of the combined piston of the present invention at one angle; Figure 2 for Figure 1 A schematic diagram of one embodiment of the piston top; Figure 3 for Figure 1 A schematic diagram of one embodiment of the central pad block.

[0022] 1. Piston top; 11. Mounting chamber; 2. Piston skirt; 3. Threaded connectors; 31. Spacers; 4. First contact surface; 5. First wear-resistant layer; 6. Second contact surface; 7. Second wear-resistant layer. Detailed Implementation

[0023] The present invention will be further described below with reference to specific embodiments and accompanying drawings. More details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from those described herein. Those skilled in the art can make similar extensions and derivations based on actual application situations without departing from the spirit of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0025] In traditional composite pistons, the piston crown 1 is made of a high-temperature alloy material, such as alloy steel, while the piston skirt 2 is made of aluminum alloy. The piston crown 1 and piston skirt 2 are connected by a threaded connector 3. The piston crown 1 and piston skirt 2 are in direct contact with the machined surfaces of the alloy steel and aluminum alloy base materials, and the contact surfaces are not specially treated, thus lacking strong wear resistance.

[0026] Furthermore, the high load-bearing capacity of combined pistons places high demands on surface integrity, including surface roughness and machining texture. In particular, the surface finish of aluminum alloys is highly sensitive to factors such as cutting tools and machining texture. Even if the surface roughness meets the technical requirements, tool marks may still be present on the surface. Based on this, traditional solutions improve the fretting wear of the contact surface by increasing the surface finish requirements, but the effect is poor and further processing significantly increases production costs.

[0027] In traditional combined pistons, the preload of the connecting bolts of the piston skirt 2 is increased to reduce the slippage between the contact surface of the piston skirt 2 and the piston top 1, thereby reducing fretting wear. However, this method requires high strength of the connecting bolts, which increases the risk of bolt breakage. In addition, aluminum alloy materials have limited load-bearing capacity. Therefore, increasing the preload of the connecting bolts cannot completely eliminate the wear on the joint surface of the combined piston.

[0028] Based on this, the present invention proposes a combined piston, which completely solves the wear problem of the contact pair of the combined piston by applying a surface treatment process to the contact surface of the piston top 1 and the piston skirt 2.

[0029] Please refer to the details. Figure 1 The combined piston proposed in this invention includes a piston top 1 and a piston skirt 2, which are connected by at least one threaded connector 3. The piston top 1 has an installation chamber 11, and one end of the piston skirt 2 is inserted into the installation chamber 11 to form a first contact surface 4 between it and the inner top wall of the piston top 1. A first wear-resistant layer 5 is provided at the first contact surface 4.

[0030] Please refer to Figure 2 The number of threaded connectors 3 can be two, four, or more, and is not limited here. When there are multiple threaded connectors 3, the multiple threaded connectors 3 are evenly distributed along a circular circumference, thereby making the connection stability between the piston top 1 and the piston skirt 2 stronger when the combined piston is running.

[0031] The aforementioned first contact surface 4 refers to the surface of the inner top wall of the piston top 1 and the top surface of the piston skirt 2 together forming the first contact surface 4. That is, the contact between the inner top wall of the piston top 1 and the top surface of the piston skirt 2 forms the first contact surface 4.

[0032] The aforementioned first wear-resistant layer 5 refers to the first wear-resistant layer 5 being provided at the first contact surface 4. However, it is not limited to whether the first wear-resistant layer 5 is provided on the piston top 1 or the piston skirt 2. It can be adjusted according to actual needs, and no limitation is made here.

[0033] The first wear-resistant layer 5 can separate the piston top 1 from the piston skirt 2. During piston operation, the first wear-resistant layer 5 plays a role in reducing and resisting wear, thereby eliminating wear on the piston skirt 2 or the piston top 1 body. At the same time, it can reduce the quality requirements for surface integrity of the piston top 1 and piston skirt 2 at the first contact surface 4.

[0034] Please refer to Figure 2 The first wear-resistant layer 5 is disposed on the inner top wall of the piston top 1, and the material of the first wear-resistant layer 5 is compatible with the material of the piston skirt 2.

[0035] Furthermore, the piston top 1 is made of a high-temperature alloy, and the piston skirt 2 is made of an aluminum alloy; the first wear-resistant layer 5 is any one of a copper plating layer, a copper alloy layer, and an aluminum alloy layer.

[0036] That is, a coating material with similar material properties and hardness to the piston skirt 2 is first selected to perform surface treatment on the high-temperature alloy material of the piston top 1 to form the first wear-resistant layer 5.

[0037] For coating materials, they need to have good thermal conductivity and a high thermal coefficient of not less than 32W / m·K at room temperature, such as one of the above-mentioned copper plating, copper alloys and aluminum alloys.

[0038] After selecting the coating material, the coating material is applied to the inner top wall of the piston top 1 to form a first wear-resistant layer 5. Preferably, the thickness of the first wear-resistant layer 5 is 0.005~0.8mm, the hardness of the first wear-resistant layer 5 is 20~200HBW, and the surface roughness of the coating is not less than Ra6.3.

[0039] The present invention uses one of copper plating, copper alloy and aluminum alloy as the first wear-resistant layer 5, which can adapt to the performance differences of the two substrates, piston skirt 2 and piston top 1. It avoids direct friction and wear between metals of different materials, and can also take into account the high temperature resistance and adhesion of the first wear-resistant layer 5.

[0040] Because the base material of piston skirt 2 is aluminum alloy, which is lightweight and has good thermal conductivity, but low hardness and high toughness. The high-temperature alloy of piston top 1 has a much higher hardness than aluminum alloy but lower toughness. If a high-temperature alloy coating is applied to the top surface of the aluminum alloy piston skirt 2, the difference in hardness and elastic modulus between the high-temperature alloy and aluminum alloy will cause slight deformation of the soft aluminum alloy base material due to reciprocating impacts and temperature fluctuations during piston operation. The hard high-temperature alloy coating cannot follow this deformation, easily leading to internal stress concentration, causing cracks and peeling of the coating. This not only fails to provide wear resistance, but the detached coating debris may also scratch the piston cavity wall or block oil passages, causing more serious malfunctions. Therefore, the first wear-resistant layer 5, made of copper plating, copper alloy, and aluminum alloy, is placed on piston top 1 instead of piston skirt 2.

[0041] In some other embodiments, the first wear-resistant layer 5 is disposed on the top surface of the piston skirt 2; the first wear-resistant layer 5 is a reinforced wear-resistant layer formed after the top surface of the piston skirt 2 has been reinforced.

[0042] Specifically, the microhardness of aluminum alloy surfaces can be enhanced through laser remelting technology, micro-arc oxidation, and other methods, thereby improving their surface wear resistance. The first wear-resistant layer 5, after strengthening treatment, has a surface hardness of 150HV~400HV, a strengthening depth of 0.005~0.3mm, and a surface roughness of not less than Ra6.3.

[0043] In some other embodiments, the first wear-resistant layer 5 is a lubricant layer, which is disposed on the inner top wall of the piston top 1 and / or the top surface of the piston skirt 2.

[0044] Specifically, the lubricant layer is made of either molybdenum disulfide or graphite.

[0045] Optionally, lubricant layers can be provided on the piston top 1 and piston skirt 2 respectively. This bidirectional arrangement can disperse the wear pressure on the contact surface, avoid excessive wear of a single wear-resistant layer, significantly extend the service life of the first wear-resistant layer 5, and improve the operational stability of the combined piston.

[0046] Alternatively, a lubricant layer can be separately installed on the piston top 1 or piston skirt 2. The specific choice can be made according to actual needs, and no limitation is made here.

[0047] That is, by coating the inner top wall of the piston top 1 and / or the top surface of the piston skirt 2 with molybdenum disulfide or graphite, the wear of the piston skirt 2 substrate material can be reduced. The thickness of the lubricant coating on the inner top wall of the piston top 1 and / or the top surface of the piston skirt 2 can be 0.005~0.1mm, and the roughness at the first contact surface 4 is not higher than 6.3.

[0048] This implementation utilizes the friction-reducing properties of solid lubricants to solve the problems of high friction coefficients and hard friction resulting from long-term use in traditional metal wear-resistant layers. Both molybdenum disulfide and graphite possess excellent high-temperature resistance and low friction coefficients, enabling the formation of a lubricating film at the first contact surface 4. This transforms the direct friction between the piston top 1 and piston skirt 2 into low-resistance friction within the lubricant, thereby significantly reducing the wear rate between the piston top 1 and piston skirt 2. Furthermore, the lubricant coating process is simple, allowing for periodic replenishment to maintain the long-term friction-reducing effect, resulting in low maintenance costs.

[0049] In some other implementations, such as Figure 1 and Figure 3 As shown, the threaded connector 3 is a bolt, and a pad 31 is provided between the bolt head and the inner wall of the piston skirt 2; a second contact surface 6 is formed between the pad 31 and the inner wall of the piston skirt 2, and a second wear-resistant layer 7 is provided at the second contact surface 6.

[0050] The present invention provides a second wear-resistant layer 7 at the second contact surface 6, which can reduce the friction and wear between the pad 31 and the inner wall of the piston skirt 2, thereby preventing the problem of bolt loosening caused by wear gaps, ensuring the long-term tightness of the threaded connection, and ultimately improving the structural stability of the combined piston.

[0051] Optionally, a second wear-resistant layer 7 is provided on the piston skirt 2 and / or the pad 31.

[0052] In this invention, the second wear-resistant layer 7 can be provided on either the piston skirt 2 or the pad 31, or both. For example, when the piston skirt 2 is made of a soft material, the second wear-resistant layer 7 can be provided only on the inner wall of the piston skirt 2; when the pad 31 is easily worn, the second wear-resistant layer 7 can be provided only on the surface of the pad 31, or both the piston skirt 2 and the pad 31 can be provided to achieve double protection.

[0053] Specifically, a second wear-resistant layer 7 can be provided on the pad 31. The second wear-resistant layer 7 is formed by coating one of copper plating, copper alloy and aluminum alloy onto the surface of the pad 31.

[0054] Alternatively, laser remelting or micro-arc oxidation can be performed on the outer surface of the piston skirt 2 to enhance the microhardness of the aluminum alloy surface and improve its surface wear resistance.

[0055] Alternatively, a second wear-resistant layer 7 can be formed by coating the piston skirt 2 and the pad 31 with a lubricant such as molybdenum disulfide or graphite.

[0056] All three methods mentioned above are acceptable, and no specific method is specified here.

[0057] This invention also proposes a combined piston wear suppression method, employing the combined piston described above, wherein the suppression method includes: A first wear-resistant layer is formed by applying a surface treatment process to the first contact surface between the piston top and the piston skirt.

[0058] In one embodiment, the first wear-resistant layer is formed by surface strengthening treatment of the top surface of the piston skirt; wherein the surface strengthening treatment method is one of laser remelting and micro-arc oxidation.

[0059] In some other embodiments, a lubricant is applied between the inner top wall of the piston crown and the top surface of the piston skirt to form the first wear-resistant layer; wherein the lubricant is either MoS2 or graphite.

[0060] Furthermore, the piston top and the piston skirt are connected by at least one threaded connector, and a pad is provided in front of the threaded connector and the piston skirt; a second wear-resistant layer is provided on the second contact surface between the pad and the piston skirt.

[0061] As described above, the wear suppression method proposed in this invention can significantly reduce frictional wear between the piston top and piston skirt during relative movement by setting a first wear-resistant layer at the first contact surface. This can prevent the piston top and piston skirt from cracking or even being damaged due to wear at the first contact surface, thereby avoiding problems such as equipment damage and loss of function. Ultimately, it can ensure the long-term stable operation of the combined piston and greatly reduce its maintenance frequency and downtime risk.

[0062] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation", "connection", "joining", and "fixing" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can also refer to mechanical connections. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0063] This application uses specific terms to describe embodiments of the application. Terms such as "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of the application. Therefore, it should be emphasized and noted that references to "an embodiment," "one embodiment," or "an alternative embodiment" in different locations throughout this specification do not necessarily refer to the same embodiment. Furthermore, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0064] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. A composite piston, characterized in that, include: A piston top and a piston skirt, the piston top and the piston skirt being connected by at least one threaded connector; The piston top has a mounting chamber, and one end of the piston skirt is inserted into the mounting chamber and forms a first contact surface with the inner top wall of the piston top. A first wear-resistant layer is provided at the first contact surface.

2. The combined piston according to claim 1, characterized in that, The first wear-resistant layer is disposed on the inner top wall of the piston top, and the material of the first wear-resistant layer is compatible with the material of the piston skirt.

3. The combined piston according to claim 2, characterized in that, The piston top is made of a high-temperature alloy, and the piston skirt is made of an aluminum alloy. The first wear-resistant layer is any one of a copper plating layer, a copper alloy layer, and an aluminum alloy layer.

4. The combined piston according to claim 1, characterized in that, The first wear-resistant layer is disposed on the top surface of the piston skirt; The first wear-resistant layer is a reinforced wear-resistant layer formed after the top surface of the piston skirt has been reinforced.

5. The combined piston according to claim 1, characterized in that, The first wear-resistant layer is a lubricant layer, which is disposed on the inner top wall of the piston top and / or the top surface of the piston skirt.

6. The combined piston according to claim 5, characterized in that, The lubricant layer is made of either molybdenum disulfide or graphite.

7. The combined piston according to claim 1, characterized in that, The threaded connector is a bolt, and a pad is provided between the bolt head and the inner wall of the piston skirt. A second contact surface is formed between the pad and the inner wall of the piston skirt, and a second wear-resistant layer is provided at the second contact surface.

8. The combined piston according to claim 7, characterized in that, The second wear-resistant layer is provided on the piston skirt and / or the pad.

9. A combined piston wear suppression method, characterized in that, The suppression method, employing the combined piston as described in any one of claims 1-8, comprises: A first wear-resistant layer is formed by applying a surface treatment process to the first contact surface between the piston top and the piston skirt.

10. The combined piston wear suppression method according to claim 9, characterized in that, The first wear-resistant layer is formed by coating the inner top wall of the piston top with one of the following materials: copper plating, copper alloy, and aluminum alloy.

11. The combined piston wear suppression method according to claim 9, characterized in that, The first wear-resistant layer is formed by surface strengthening treatment of the top surface of the piston skirt; wherein the surface strengthening treatment method is one of laser remelting and micro-arc oxidation.

12. The combined piston wear suppression method according to claim 9, characterized in that, A lubricant is applied between the inner top wall of the piston crown and the top surface of the piston skirt to form the first wear-resistant layer; wherein the lubricant is either MoS2 or graphite.

13. The combined piston wear suppression method according to claim 9, characterized in that, The piston top and the piston skirt are connected by at least one threaded connector, and a pad is provided in front of the threaded connector and the piston skirt; A second wear-resistant layer is provided on the second contact surface between the pad and the piston skirt.

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