Heat insulation piston structure and preparation method therefor

Abstract

A heat insulation piston structure (100), comprising a head (200) and a piston skirt portion (300), wherein the head (200) is provided at the top end of the piston skirt portion (300), and the head (200) is divided into a first head portion (210) and a second head portion (220); the first head portion (210) is welded to the second head portion (220); a sealed cavity (250) is formed between the first head portion (210) and the second head portion (220); and a support is fixed inside the sealed cavity (250).

Description

A heat-insulating piston structure and its preparation method Technical Field

[0001] The invention belongs to the field of internal combustion engines, and in particular relates to a heat-insulating piston structure. Background Art

[0002] An insulated piston is a piston used in internal combustion engines. Its main function is to reduce the heat transfer from the combustion chamber to the outside, improve the thermal efficiency of the engine, thereby reducing the temperature of the piston and piston rings and extending their service life.

[0003] As engine emission standards increase, engines are required to have greater explosion pressure. As the pressure increases, the temperature and pressure of the piston combustion chamber and top surface also continue to increase, causing the temperature of the ring groove and pin hole to be too high.

[0004] In order to ensure that the temperature of the ring groove, pin hole and skirt is not too high, a cooling oil cavity is provided in the forged steel piston, so that the piston combustion chamber, top surface and cooling oil cavity can exchange heat, thereby reducing the temperature of the ring groove and skirt; however, the provision of a cooling oil cavity will lead to large heat loss in the combustion chamber and top surface, and the thermal efficiency of the engine is low. 25% of the total energy generated by combustion in the piston combustion chamber is dissipated through the cylinder liner and cooling oil channel; and the high temperature of the combustion chamber surface and the temperature difference of the cooling oil channel are huge, resulting in large thermal stress in the piston combustion chamber, increasing the risk of cracking.

[0005] To address this issue, existing technologies typically apply a thermal insulation coating to the top surface of the combustion chamber. However, in actual use, the coating's thinness (only 0.03-0.3 mm) makes it ineffective in blocking heat transfer to the piston rings and skirt. Chinese invention patent CN201610539558 discloses an insulated piston that effectively reduces heat loss from the combustion chamber. However, in actual use, the insulation layer blocks heat from the combustion chamber, causing the piston combustion chamber temperature, particularly at the combustion chamber throat, to rise sharply. This high temperature can cause cracking and ablation in the spray-on sealing layer at the combustion chamber throat. Furthermore, the insulation layer is cast directly onto the base, and due to the different thermal expansion coefficients of the two materials, this can easily cause the sealing layer to separate from the base.

[0006] In summary, there is an urgent need for a piston with good thermal insulation effect and high safety to solve the problem that the existing piston thermal insulation coating has poor thermal insulation and the thermal insulation layer is prone to cracks and damage at high temperatures. Summary of the Invention

[0007] An embodiment of the present invention provides a heat-insulating piston structure, which aims to solve the problem that the existing piston heat-insulating coating has poor heat insulation and the heat-insulating layer is prone to cracking and damage at high temperatures.

[0008] The embodiment of the present invention is implemented as follows:

[0009] A heat-insulating piston structure, comprising:

[0010] The top end of the piston skirt is provided with a head;

[0011] The head portion is divided into a first head portion and a second head portion, the first head portion and the second head portion are welded together, a sealed cavity is formed between the first head portion and the second head portion, and a support is fixed inside the cavity.

[0012] Furthermore, a support is passed through the sealed cavity, one end of the support is connected to the first head, and the other end of the support is connected to the second head.

[0013] Furthermore, the support is a porous full support or a solid partial support;

[0014] All the supports are provided with through holes, through which the cavities in the sealed cavity can be interconnected.

[0015] Furthermore, the sealed cavity surrounds the entire combustion chamber surface, or is separately provided on one side of the oil passage and / or one side of the inner cavity.

[0016] Furthermore, the first head is at the upper end of the second head, the second head is arranged at the upper end of the piston skirt, and the second head is connected to the piston skirt by welding.

[0017] Furthermore, the thickness of all supports is 0.5 mm to 5 mm, and the thickness of local supports is 5 to 20 mm.

[0018] A method for preparing a heat-insulating piston structure, comprising:

[0019] Manufacturing a semi-finished product of the piston, and forging the piston skirt, the first head, and the second head into semi-finished products before welding;

[0020] The supports are cast and processed into the specified size;

[0021] Place the support between the first head and the second head for compaction and assembly;

[0022] Weld the assembled head;

[0023] The head and the skirt are welded into a whole;

[0024] Through heat treatment, fine processing and surface treatment to finished product.

[0025] The beneficial effects achieved by the present invention are:

[0026] The present invention forms a sealed cavity between the first head and the second head, thereby reducing heat loss, improving combustion efficiency, reducing energy loss, and reducing the heat load of the engine. The enclosed space reduces heat transfer between the top surface, the combustion chamber, the cooling oil channel, and the inner cavity, thereby achieving a heat insulation effect and high working reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG1 is a schematic structural diagram of all supports provided by the present invention;

[0028] FIG2 is a cross-sectional schematic diagram of an unsupported sealed cavity provided by the present invention;

[0029] FIG3 is a cross-sectional schematic diagram of a cavity provided by the present invention disposed on one side of an oil passage;

[0030] FIG4 is a schematic structural diagram of a local support provided by the present invention;

[0031] FIG5 is a schematic diagram of a structure in which a cavity surrounds the entire combustion chamber surface provided by the present invention;

[0032] FIG6 is a schematic structural diagram of all supports provided by the present invention;

[0033] 7 is a flow chart of a method for manufacturing a heat-insulating piston structure provided by the present invention;

[0034] FIG8 is a schematic diagram of the processing of the local support structure provided by the present invention.

[0035] Figure Number:

[0036] 100. Heat-insulating piston structure;

[0037] 200. Head; 210. First head; 220. Second head; 230. All supports; 240. Partial supports; 250. Cavity; 300. Piston skirt. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0039] The present invention provides a head and a piston skirt, and the head and the piston skirt are manufactured separately, which reduces the difficulty of manufacturing and facilitates manufacturing. At the same time, the first head and the second head are manufactured separately, and a sealed cavity is formed between the first head and the second head, which can reduce heat loss, improve combustion efficiency, reduce energy loss, and reduce the heat load of the engine. At the same time, a support passes through the sealed cavity to maintain the shape of the sealed cavity. The closed space reduces the heat transfer between the top surface, the combustion chamber, the cooling oil channel, and the inner cavity, thereby achieving a heat insulation effect and high working reliability. Example 1

[0040] 1 , 2 and 5 , in an embodiment of the present invention, a heat-insulating piston structure 100 is provided, comprising: a piston skirt 300 , the piston skirt 300 being forged, a head 200 being provided at the top end of the piston skirt 300 , a support being fixed inside the head 200 ;

[0041] The head portion 200 is divided into a first head portion 210 and a second head portion 220 . The first head portion 210 and the second head portion 220 are welded together. A sealed cavity 250 is formed between the first head portion 210 and the second head portion 220 . A support member passes through the sealed cavity 250 .

[0042] As shown in reference figure 2, one end of the support is connected to the first head 210, and the other end is connected to the second head 220. The support is a porous full support 230 or a solid partial support 240, wherein the full support 230 is provided with a through hole, through which the cavities 250 in the sealed cavity 250 can be interconnected. The partial support 240 is a solid connecting column, the upper end of the connecting column is connected to the first head 210, and the lower end is connected to the second head 220.

[0043] In this embodiment, the insulating piston is a piston used inside the engine cylinder to reduce heat transfer and energy loss. In order to avoid heat loss, the existing insulating piston is coated with a ceramic coating on the piston head, which can effectively reduce heat conduction. However, the existing insulation layer is prone to cracks and damage at high temperatures. In order to solve the problem of damage to the existing insulation coating, this embodiment provides an insulating piston structure 100. By providing a closed cavity 250 on the head 200, it plays a role in isolating heat transfer, which can reduce heat loss between the piston and the piston ring, improve combustion efficiency, reduce energy loss, and reduce the heat load of the engine.

[0044] Specifically, in one embodiment, the piston skirt 300 is forged, a head 200 is provided at the top of the piston skirt 300 , and a support is fixed inside the head 200 .

[0045] The piston skirt 300 is located between the piston head and the piston pin and is the main part of the piston. The piston skirt is connected to the connecting rod through the piston pin, and the piston skirt enables the piston to reciprocate in the cylinder. In this embodiment, the piston skirt 300 can be formed by forging or casting. The specific processing method can be selected according to actual needs.

[0046] Referring to Figure 1, in another embodiment, a support is fixed inside the head 200, and the support is used to prevent excessive pressure in the combustion chamber of the head, which may cause serious deformation of the combustion chamber. In order to prevent heat from being transferred and lost through the support, all supports 230 are made of a material with a thermal conductivity coefficient of less than 5W / m*K. All supports 230 are provided with porous materials, and the holes are interconnected, and the material is a heat-insulating substance.

[0047] The material of the local support 240 can be metal, such as alloy steel; it can also be a polymer material, such as polystyrene, polyurethane, etc. The above specific description of the local support 240 is only exemplary and should not be understood as a limitation to this embodiment. It can be selected according to actual needs.

[0048] The number of local supports 240 can be one, two, three, or four, and the specific number can be selected according to actual needs. The shape of the local support 240 can be cylindrical or long, and the specific shape can be selected according to actual installation needs.

[0049] In another embodiment, the head 200 is divided into a first head 210 and a second head 220 , the first head 210 and the second head 220 are welded together, and a sealed cavity 250 is formed between the first head 210 and the second head 220 , and a support passes through the sealed cavity 250 .

[0050] It is easy to understand that the head portion 200 is specifically divided into a first head portion 210 and a second head portion 220. The first head portion 210 and the second head portion 220 can be manufactured separately by stamping or forging. The first head portion 210 and the second head portion 220 are fixedly connected by welding. The specific welding method can be any welding method, such as friction welding, electron beam welding, laser welding, etc. After the first head portion 210 and the second head portion 220 are welded, a sealed cavity 250 is formed between the first head portion 210 and the second head portion 220. A support member passes through the sealed cavity 250.

[0051] Specifically, the first head 210 and the piston skirt 300 can be connected by inlaying or fixed by welding, and the second head 220 and the piston skirt 300 can be connected by inlaying or welding. The above is the specific connection method between the first head 210 and the second head 220 and the piston skirt 300. The above description of the connection method between the first head 210 and the second head 220 and the piston skirt 300 is only exemplary.

[0052] In this embodiment, one end of the support can be connected to the first head 210 by means of inlay, and the other end of the support can be connected to the second head 220 by means of inlay. It is easy to understand that the first head 210 and the second head 220 can be connected by the support, and a certain cavity 250 can be formed between the first head 210 and the second head 220 by the support.

[0053] 7 and 8 , a method for preparing a heat-insulating piston structure includes:

[0054] S1. Manufacturing a semi-finished piston by forging the piston skirt, the first head, and the second head into semi-finished products before welding;

[0055] S2. The support is cast and processed into the specified size;

[0056] S3, placing the support between the first head and the second head for compaction and assembly;

[0057] S4, welding the assembled head;

[0058] S5. Welding the head and skirt into a whole;

[0059] S6. Through heat treatment, fine processing and surface treatment to the finished product.

[0060] Based on the above structure, when the piston is manufactured, the piston skirt 300 can be manufactured by a forging process. At the same time, the first head 210 and the second head 220 can be manufactured by a casting process through a forging process. Then, the support 230 can be manufactured by a casting or forging process. One end of the support 230 is embedded and connected with the first head 210, and the other end of the support 230 is embedded and connected with the second head 220. Then, the first head 210 and the second head 220 are fixedly connected by welding, and then the welded head 200 is fixedly connected to the piston skirt 300 by welding.

[0061] The head 200 and the piston skirt 300 are manufactured separately, which reduces the difficulty of manufacturing and facilitates manufacturing and replacement. At the same time, the first head 210 and the second head 220 are manufactured separately, and a sealed cavity is formed between the first head 210 and the second head 220, which can reduce heat loss, improve combustion efficiency, reduce energy loss, and reduce the heat load of the engine. At the same time, a support 230 passes through the sealed cavity to maintain the shape of the sealed cavity, and reduces the heat transfer between the top surface, the combustion chamber and the cooling oil channel, and the inner cavity through the closed space, thereby achieving a heat insulation effect and high working reliability. Example 2

[0062] 4 and 5 , in an embodiment of the present invention, the sealed cavity 250 surrounds the entire combustion chamber surface, or is separately provided on one side of the oil passage and / or one side of the inner cavity.

[0063] In one embodiment, a sealed cavity 250 surrounds the entire surface of the combustion chamber. The combustion chamber refers to an area within the engine used for the combustion of mixed air and fuel. The combustion chamber portion of the insulated piston is used to accommodate the combustion process. A sealed cavity 250 is provided on the back of the combustion chamber. The sealed cavity 250 can separate the first head 210 and the second head 220, thereby keeping heat in the combustion chamber and the top surface, which helps to improve combustion efficiency and reduce emissions.

[0064] In another embodiment, the sealed cavity 250 is separately provided on one side of the oil passage. The oil passage is a pipe or channel for transferring heat and coolant. In the heat-insulating piston, by providing the cavity 250 on one side of the oil passage, the oil passage can be isolated from the combustion chamber, reducing the channel for downward heat transfer from the head 200 and reducing the cooling of the oil passage.

[0065] In another embodiment, the sealed cavity 250 is separately arranged on one side of the inner cavity. The inner cavity refers to the space inside the piston, which is used to accommodate the piston pin and other parts. In the insulated piston, the design of the inner cavity helps to reduce the weight of the piston and improve the heat conduction performance of the piston.

[0066] In another embodiment, a sealed cavity 250 is provided on one side of the oil passage and one side of the inner cavity. The sealed cavity 250 can reduce the channel for downward heat transfer from the head 200, reduce the heat transfer between the top surface, the combustion chamber and the cooling oil passage, and the inner cavity, thereby achieving a heat insulation effect. Example 3

[0067] 2 , in the embodiment of the present invention, the lower end surface of the first head 210 and the upper end surface of the second head 220 are complementary in shape.

[0068] In this embodiment, the shapes of the lower end surface of the first head 210 and the upper end surface of the second head 220 are complementary. It is easy to understand that by setting complementary shapes, when the first head 210 and the second head 220 are welded, the thickness of the closed cavity 250 formed by the first head 210 and the second head 220 is the same, which can avoid uneven heating.

[0069] The shape of the sealed cavity 250 can be symmetrical about the central axis of the piston, so that the piston can be evenly stressed when the piston is working, thereby preventing uneven stress from hitting the cylinder wall. Example 4

[0070] 1 , in an embodiment of the present invention, the first head portion 210 is located at the upper end of the second head portion 220 , the second head portion 220 is located at the upper end of the piston skirt portion 300 , and the second head portion 220 and the piston skirt portion 300 are connected by welding.

[0071] In this embodiment, the first head portion 210 is located at the upper end of the second head portion 220 , and the second head portion 220 is disposed at the upper end of the piston skirt portion 300 by welding.

[0072] The first head portion 210 and the second head portion 220 , as well as the second head portion 220 and the piston skirt portion 300 are connected by welding, which has a simple process, a reliable connection, and reduces manufacturing difficulty. Example 5

[0073] 4 , in the embodiment of the present invention, the thickness of all supports 230 is 0.5 mm to 5 mm, and the thickness of the partial supports 240 is 5 mm to 20 mm.

[0074] In this embodiment, the thickness of all supports 230 is 0.5mm-5mm, specifically 0.5mm, 1mm, 1.5mm, 3mm, 4mm or 5mm. The above are specific examples of the thickness of all supports 230. It is easy to understand that the thickness of all supports 230 in the present invention is not limited to the above specific examples.

[0075] In another embodiment, the thickness of the local support 240 is 5-20 mm, specifically 5 mm, 6 mm, 10 mm, 15 mm or 20 mm, and the specific value can be selected according to actual needs.

[0076] By providing a support of a single thickness, the heat received by the support can be made more uniform, thus avoiding structural stress caused by uneven heating, which in turn causes cracks in the device. At the same time, providing a support of a single thickness makes the support easier to manufacture, reducing the manufacturing difficulty.

[0077] The foregoing description of this specification describes specific embodiments. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in an order different from that described in the embodiments and still achieve the desired results. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the specific order shown or sequential order to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0078] It should be noted that for the aforementioned method embodiments, for the sake of simplicity of description, they are all expressed as a series of action combinations, but those skilled in the art should be aware that this application is not limited by the order of the actions described, because according to this application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in this specification are all preferred embodiments, and the actions and modules involved are not necessarily required by this application.

[0079] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0080] The embodiments of the present application are described in detail above in conjunction with the accompanying drawings, but the present application is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the technical field without departing from the purpose of the present application.

Claims

1. A heat-insulating piston structure, characterized in that: include: The top end of the piston skirt is provided with a head; The head portion is divided into a first head portion and a second head portion, the first head portion is welded to the second head portion, a sealed cavity is formed between the first head portion and the second head portion, and a support is fixed inside the cavity.

2. The heat-insulating piston structure according to claim 1, characterized in that: A support runs through the sealed cavity, one end of the support is connected to the first head, and the other end of the support is connected to the second head.

3. The heat-insulating piston structure according to claim 2, characterized in that: The support is a porous full support or a solid partial support; All the supports are provided with through holes, through which the cavities in the sealed cavity can be interconnected.

4. The heat-insulating piston structure according to claim 1, characterized in that: The sealing cavity surrounds the entire combustion chamber surface, or is separately arranged on one side of the oil passage and / or one side of the inner cavity.

5. The heat-insulating piston structure according to claim 1, wherein the first head portion is at the upper end of the second head portion, the second head portion is arranged at the upper end of the piston skirt portion, and the second head portion is connected to the piston skirt portion by welding.

6. The heat-insulating piston structure according to claim 1, characterized in that: The thickness of the entire support is 0.5 mm to 5 mm, and the thickness of the local support is 5 to 20 mm.

7. A method for preparing a heat-insulating piston structure, characterized in that: include: Manufacturing a semi-finished product of the piston, and processing the piston skirt, the first head, and the second head into semi-finished products before welding by forging; The support is cast and processed into the specified size; Placing the support between the first head and the second head for compaction and assembly; Weld the assembled head; The head and the skirt are welded into a whole; Through heat treatment, fine machining and surface treatment to the finished product.

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