Diesel engine

Abstract

The invention relates to the technical field of diesel engines, in particular to a diesel engine which comprises a cylinder body and a cylinder cover arranged on the cylinder body in a covering mode, a combustion chamber is arranged between the cylinder body and the cylinder cover, a sealing gasket used for sealing the combustion chamber is arranged between the cylinder body and the cylinder cover, and a nested structure is arranged between the cylinder body and the cylinder cover. The cylinder body and the cylinder cover are different in thermal expansion coefficient, the nested structure is in clearance fit when the cylinder body and the cylinder cover are assembled, after the diesel engine operates and is heated, the nested structure is changed into interference fit from clearance fit and forms a sealing structure used for sealing a combustion chamber, and after the diesel engine operates for a certain time, the sealing structure can seal the combustion chamber. A gap at the nested structure is gradually reduced and forms a sealing surface, so that the combustion chamber between the cylinder body and the cylinder cover is sealed, the sealing gasket of the combustion chamber of the cylinder body and the cylinder cover is sealed at the beginning of the diesel engine, the combustion chamber of the diesel engine is sealed stably and reliably, and the whole operation of the diesel engine is stable and reliable; and the maintenance frequency and the use cost are reduced.

Description

Technical Field

[0001] This invention relates to the field of diesel engine technology, and in particular to a diesel engine. Background Technology

[0002] Diesel engines, with their outstanding reliability, high thermal efficiency, low fuel consumption, and long service life, are widely used in many key fields such as industry, shipbuilding, power generation, and heavy machinery. Especially in diesel generator sets, the diesel engine, as the core power source, directly affects the overall system's performance. The core structure of a diesel engine mainly includes the cylinder block and the cylinder head mounted on top of the cylinder block, forming a sealed combustion chamber space. This combustion chamber is used for fuel combustion to drive the piston and perform work.

[0003] Currently, most diesel engines use gaskets to seal between the cylinder block and cylinder head. These gaskets are tightened under pressure during assembly and pressed against a flat surface to ensure the combustion chamber's initial airtightness. However, with the increasing cylinder diameter in diesel engines, the distance between the four fastening studs also increases. This leads to insufficient pressure at the sealing interface between two studs, causing leakage. If cylinder blow occurs, it can even cause the diesel engine to shut down and malfunction, requiring gasket replacement, which is time-consuming and labor-intensive.

[0004] Because gaskets fail frequently, users must often shut down the machine to replace them. This not only significantly shortens the equipment maintenance cycle and increases maintenance costs and disassembly workload, but also affects the equipment's availability and operating economy. Therefore, there is an urgent need for an improved structure that can adapt to high-temperature and high-pressure environments and has long-lasting sealing capabilities to improve the overall reliability and service life of diesel engines. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: in order to solve the problem of combustion chamber seal failure that easily occurs in existing diesel engines during operation, a diesel engine is provided.

[0006] The technical solution adopted by this invention to solve its technical problem is as follows: a diesel engine, including a cylinder block and a cylinder head mounted on the cylinder block, a combustion chamber disposed between the cylinder block and the cylinder head, and a sealing gasket for sealing the combustion chamber disposed between the cylinder block and the cylinder head. The cylinder block and the cylinder head have a nested structure, and the cylinder block and the cylinder head have different coefficients of thermal expansion. During assembly, the nested structure is a clearance fit. After the diesel engine heats up during operation, the nested structure changes from a clearance fit to an interference fit, forming a sealing structure for sealing the combustion chamber. By setting a nested structure between the cylinder block and the cylinder head, and taking advantage of the different coefficients of thermal expansion between them, the gap at the nested structure gradually decreases after the diesel engine has been running for a period of time, forming a sealing surface, thus sealing the combustion chamber between the cylinder block and the cylinder head. Simultaneously, the sealing gasket, which seals the combustion chamber at the beginning of the diesel engine's operation, ensures stable and reliable combustion chamber sealing throughout the entire operation of the diesel engine, thereby ensuring the overall stable and reliable operation of the diesel engine, reducing maintenance frequency, and lowering operating costs.

[0007] To achieve a nested structure, in some preferred embodiments, the nested structure includes a first boss on the cylinder block, a first groove on the cylinder head, the first groove matching the first boss, the first boss being disposed within the first groove, the coefficient of thermal expansion of the cylinder head being less than that of the cylinder block, and a sealing gasket being disposed within the first groove. By providing a first boss on the cylinder block, with one end of the combustion chamber located on the first boss and cooperating with the first groove on the cylinder head, a nested structure between the cylinder block and cylinder head is achieved.

[0008] To facilitate the sealing of the gasket on the cylinder block and cylinder head, in some preferred embodiments, the gasket has an annular structure and matches a first groove, with the gasket positioned at the bottom of the first groove. By placing the gasket within the first groove, the gasket is positioned using the first groove, and the installation of the gasket simultaneously satisfies the sealing requirements of the gasket on the cylinder block and cylinder head.

[0009] To achieve the difference in thermal expansion coefficients between the cylinder block and cylinder head, in some preferred embodiments, the cylinder block is made of aluminum alloy ADC12, and the cylinder head is made of aluminum alloy A356. The thermal expansion coefficient of the cylinder block is higher than that of the cylinder head, enabling a seal to be achieved at the nested structure between the cylinder block and cylinder head during thermal expansion.

[0010] To achieve another method of nested structure, some preferred embodiments include a second boss on the cylinder head, a cylinder liner fitted inside the cylinder block, the second boss matching and positioned within the cylinder liner, and a sealing gasket surrounding the second boss. The coefficient of thermal expansion of the cylinder liner is less than that of the cylinder head. By providing a second boss on the cylinder head, which cooperates with the cylinder liner on the cylinder block, another nested structure between the cylinder block and cylinder head is achieved.

[0011] To achieve the difference in thermal expansion coefficients between the cylinder block and cylinder head, in some preferred embodiments, the cylinder head is made of A356 steel, and the cylinder liner is made of boron cast iron. The thermal expansion coefficient of the cylinder head is higher than that of the cylinder liner, enabling a seal to be achieved at the nested structure between the cylinder head and cylinder liner during thermal expansion.

[0012] Since the gasket is located on the periphery, in some preferred embodiments, a positioning mechanism for positioning the gasket is provided between the cylinder block and the cylinder head to facilitate its installation. By providing a positioning mechanism on the gasket, the gasket is positioned, making its installation convenient and quick.

[0013] To implement the positioning mechanism, in some preferred embodiments, the positioning mechanism includes a positioning pin, a first pin hole is provided on the cylinder head, a second pin hole is provided on the cylinder body, the first pin hole and the second pin hole are provided correspondingly, a positioning groove matching the positioning pin is provided on the sealing gasket, and the positioning pin is sequentially disposed in the first pin hole, the positioning groove and the second pin hole.

[0014] To better seal the cylinder block and cylinder head, in some preferred embodiments, the sealing gasket is made of copper, and the cylinder head has several spaced grooves with openings facing the sealing gasket. By using copper as the sealing gasket material and providing grooves on the cylinder head with openings facing the sealing gasket, an indentation is created on the sealing gasket when the cylinder block and cylinder head are tightened, resulting in deformation at the grooves and thus a better seal between the cylinder block and cylinder head.

[0015] The beneficial effects of this invention are as follows: In the diesel engine of this invention, a nested structure is set between the cylinder block and the cylinder head. Taking advantage of the different thermal expansion coefficients between the cylinder block and the cylinder head, the gap at the nested structure gradually decreases and forms a sealing surface after the diesel engine has been running for a period of time. This achieves a seal on the combustion chamber between the cylinder block and the cylinder head. Simultaneously, the sealing gaskets work together to seal the combustion chamber of the cylinder block and cylinder head at the beginning of the diesel engine's operation, ensuring stable and reliable combustion chamber sealing throughout the entire operation of the diesel engine. This ensures the overall stable and reliable operation of the diesel engine, reduces maintenance frequency, and lowers operating costs. It also avoids the problem that as the cylinder diameter increases, the distance between the four fastening studs also increases, leading to insufficient clamping force at the sealing interface between two studs and leakage. This can cause the diesel engine to stop and malfunction if cylinder blow occurs. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] Figure 1 This is a three-dimensional structural schematic diagram of Embodiment 1 of the present invention; Figure 2 This is an exploded view of Embodiment 1 of the present invention; Figure 3 yes Figure 2 A magnified view of part A in the image; Figure 4 This is a three-dimensional structural schematic diagram of the cylinder head in Embodiment 1 of the present invention; Figure 5 This is a front view of Embodiment 1 of the present invention; Figure 6 This is a left view of Embodiment 1 of the present invention; Figure 7 yes Figure 6 A magnified view of part B in the image; Figure 8 This is a schematic diagram of the nested structure in Embodiment 1 of the present invention; Figure 9 This is an exploded view of Embodiment 2 of the present invention; Figure 10 yes Figure 9 A magnified view of part C; Figure 11 This is a three-dimensional structural schematic diagram of the cylinder head in Embodiment 2 of the present invention; Figure 12 This is a left view of Embodiment 2 of the present invention; Figure 13 yes Figure 12 A magnified view of part D; Figure 14 This is a schematic diagram of Embodiment 2 of the present invention. Figure 1 ; Figure 15 This is a schematic diagram of Embodiment 2 of the present invention. Figure 2 .

[0018] In the diagram: 1. Cylinder block, 2. Cylinder head, 3. Combustion chamber, 4. Sealing gasket, 5. First boss, 6. First groove, 7. Second boss, 8. Groove, 9. Cylinder liner, 10. Locating pin, 11. First pin hole, 12. Second pin hole, 13. Locating groove. X represents the length between several slots, and Y represents the cross-sectional length of the sealing gasket. Detailed Implementation

[0019] Example 1, such as Figure 1-8 As shown, the existing cylinder block 1 and cylinder block 2 are fixedly connected by four bolts. As the cylinder diameter increases, the distance between the four fastening studs also increases, resulting in insufficient sealing force at the sealing interface between two studs and leakage. High-temperature combustion gas escapes from the combustion chamber 3, which not only causes a decrease in diesel engine power and a deterioration in fuel economy, but also causes overheating damage to surrounding components. In severe cases, it can even lead to the diesel engine stopping and failing to work properly. To solve the problem, the common approach is to increase the number of bolts to address insufficient sealing force. However, since cylinder head 2 requires air intake, the four bolts already occupy a significant portion of the space. Furthermore, there is insufficient space on cylinder block 1 to machine threaded holes for the bolts, making it impossible to add more bolts. Increasing the number of bolts would require redesigning cylinder block 1 and cylinder head 2, which is time-consuming and labor-intensive. Therefore, to address this issue, a diesel engine is used, comprising cylinder block 1 and cylinder head 2. Cylinder head 2 is mounted on cylinder block 1, and cylinder block 1 and cylinder head 2 are fastened together by four bolts. A combustion chamber 3 is located between cylinder block 1 and cylinder head 2, and a sealing gasket 4 is placed between cylinder block 1 and cylinder head 2 to form a seal for combustion chamber 3. The cylinder block 1 and cylinder head 2 have a nested structure with different coefficients of thermal expansion. When the cylinder block 1 and cylinder head 2 are assembled, the nested structure is a clearance fit. After the diesel engine has been running for a period of time, the combustion chamber 3 is under high temperature and pressure. Due to the difference in the coefficients of thermal expansion, the clearance fit between the cylinder block 1 and cylinder head 2 changes to an interference fit, forming a sealing structure for sealing the combustion chamber 3. This achieves another seal between the cylinder block 1 and cylinder head 2. This seal ensures that the combustion chamber 3 is always sealed during the operation of the diesel engine. The function of the sealing gasket 4 is to ensure a stable and reliable seal for the combustion chamber 3 when the diesel engine is first running. By adopting two sealing measures, the diesel engine can be ensured to operate stably and reliably for a long time, and the leakage of the combustion chamber 3 can be avoided, which would cause insufficient cylinder pressure.

[0020] The nested structure includes a first boss 5 on the cylinder block 1, a first groove 6 on the cylinder head 2, the first groove 6 matching the first boss 5, the first boss 5 being disposed within the first groove 6, a sealing gasket 4 located within the sealing structure, and a combustion chamber 3 located on the first boss 5. In this embodiment, the cylinder block 1 is made of ADC12, with a coefficient of thermal expansion of 21.5-23.0 μm / m·℃, and the cylinder head 2 is made of A356, with a coefficient of thermal expansion of 20.5- The coefficient of thermal expansion is 21.5 μm / m·℃, meaning that the cylinder block 1 has a large coefficient of thermal expansion and the cylinder head 2 has a small coefficient of thermal expansion. Due to the difference in the coefficients of thermal expansion between the cylinder block 1 and the cylinder head 2, the gap between the cylinder block 1 and the cylinder head 2 gradually decreases and forms a sealing surface after the diesel engine has been running for a period of time. Therefore, the thermal deformation of the first groove 6 is small, while the cylinder block 1 deforms greatly under high temperature and high pressure for a long time. The clearance fit between the cylinder block 1 and the cylinder head 2 becomes an interference fit, so that the gap between the first groove 6 and the first boss 5 gradually decreases until it is sealed, thus achieving the sealing of the combustion chamber 3.

[0021] The sealing gasket 4 has an annular structure and matches the first groove 6. The first groove 6 has a positioning function for the sealing gasket 4. The sealing gasket 4 is located at the bottom of the first groove 6 and is also located at one end of the first protrusion 5. The sealing gasket 4 is made of copper. The cylinder head 2 has a number of slots 8 with openings facing the sealing gasket 4 at intervals. The slots 8 are located above the sealing gasket 4. Since the sealing gasket 4 is made of copper, after the cylinder head 2 is pressed down, an indentation will be left on the sealing gasket 4 at the position corresponding to the slot 8. Therefore, the fit between the sealing gasket 4 and the slots forms a labyrinth seal. The length between the slots 8 is X, and the cross-sectional length of the sealing gasket 4 is Y. The length X between the slots 8 is less than the cross-sectional length Y of the sealing gasket 4. The length direction between the slots 8 and the cross-sectional length direction of the sealing gasket 4 are both arranged radially along the combustion chamber 3.

[0022] Example 2, as Figure 9-15As shown, the difference between Example 2 and Example 1 lies in the different nested structures. Specifically, the nested structure includes a second boss 7 on the cylinder head 2, and the combustion chamber 3 includes a cylinder liner 9 inside the cylinder block 1. The cylinder liner 9 is integrally cast during the manufacturing of the cylinder block 1. The second boss 7 is located inside the cylinder liner 9, and the sealing gasket 4 is located outside the sealing structure. The coefficient of thermal expansion of the cylinder liner 9 is less than that of the cylinder head 2. Specifically, the cylinder head 2 is made of aluminum alloy A356, with a coefficient of thermal expansion of 21-24 μm / m·℃, and the cylinder liner 1 is made of boron cast iron, with a coefficient of thermal expansion of 10-12. μm / m·℃, it can be seen that the expansion coefficient of the cylinder head 2 material is greater than that of the cylinder liner 1. After the diesel engine has been running for a period of time, the deformation of the second boss 7 on the cylinder head 2 is large, while the deformation of the cylinder liner 9 is small. Therefore, the gap between the second boss 7 and the cylinder liner 9 gradually decreases and forms a seal, and the clearance fit between the second boss 7 and the cylinder liner 9 becomes an interference fit, thus achieving the sealing of the combustion chamber. Furthermore, the sealing gasket 4 is located on the periphery of the nested structure in this embodiment. Therefore, the impact on the sealing gasket 4 is small when the diesel engine is running. The impact energy of the nested structure after expansion and sealing is even smaller, which can well ensure the sealing performance of the sealing gasket 4.

[0023] The sealing gasket 4 has an annular structure. A positioning mechanism is provided between the cylinder body 1 and the cylinder head 2. The positioning mechanism is used to position the sealing gasket 4. The positioning mechanism includes a positioning pin 10. The cylinder head 2 is provided with a first pin hole 11, and the cylinder body 1 is provided with a second pin hole 12. The first pin hole 11 and the second pin hole 12 are provided correspondingly. The sealing gasket 4 is provided with a positioning groove 13 that matches the positioning pin 10. The positioning groove 13 is an arc-shaped groove. The positioning pin 10 is sequentially arranged in the first pin hole 11, the positioning groove 13, and the second pin hole 12 to position the sealing gasket 4 between the cylinder body 1 and the cylinder head 2.

[0024] The principle is that during assembly, the nested structure on cylinder block 1 and cylinder head 2 is a clearance fit, which is also to facilitate the installation of cylinder block 1 and cylinder head 2. In the early stage of diesel engine operation, since the nested structure on cylinder block 1 and cylinder head 2 is a clearance fit, the sealing gasket 4 between cylinder block 1 and cylinder head 2 is used to seal the combustion chamber 3 to ensure the normal operation of the diesel engine in the early stage. After the diesel engine has been running for a period of time, the nested structure is subject to thermal expansion and contraction. The different coefficients of thermal expansion of the nested structure result in a difference in the coefficients of thermal expansion, which causes the gap at the nested structure to gradually decrease, eventually forming a seal. This seals the combustion chamber 3 at the cylinder block 1 and cylinder head 2, ensuring that the combustion chamber 3 is sealed stably and reliably during operation, thus guaranteeing the stable and reliable operation of the diesel engine.

[0025] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A diesel engine comprising a cylinder block (1) and a cylinder head (2) arranged on the cylinder block (1), a combustion chamber (3) being arranged between the cylinder block (1) and the cylinder head (2), a sealing gasket (4) being arranged between the cylinder block (1) and the cylinder head (2) for sealing the combustion chamber (3), characterized in that: The cylinder block (1) and cylinder head (2) are nested. The cylinder block (1) and cylinder head (2) have different coefficients of thermal expansion. The nested structure is a clearance fit when the cylinder block (1) and cylinder head (2) are assembled. After the diesel engine is heated during operation, the nested structure changes from a clearance fit to an interference fit and forms a sealing structure for sealing the combustion chamber (3).

2. A diesel engine according to claim 1, characterised in that: The nested structure includes a first boss (5) on the cylinder body (1), a first groove (6) on the cylinder head (2), the first groove (6) matching the first boss (5), the first boss (5) being located in the first groove (6), the coefficient of thermal expansion of the cylinder head (2) being less than the coefficient of thermal expansion of the cylinder body (1), and the sealing gasket (4) being located in the first groove (6).

3. A diesel engine according to claim 2, characterized in that: The cylinder body (1) is made of aluminum alloy ADC12, and the cylinder head (2) is made of aluminum alloy A356.

4. A diesel engine according to claim 1, characterized in that: The nested structure includes a second boss (7) on the cylinder head (2), the combustion chamber (3) includes a cylinder liner (9) inside the cylinder block (1), the second boss (7) matches the cylinder liner (9) and is located inside the cylinder liner (9), the sealing gasket (4) is fitted around the second boss (7), and the expansion coefficient of the cylinder liner (9) is less than that of the cylinder head (2).

5. A diesel engine according to claim 4, characterized in that: The cylinder head (2) is made of aluminum alloy A356, and the cylinder liner (9) is made of boron cast iron.

6. A diesel engine according to claim 4, characterized in that: A positioning mechanism for positioning the sealing gasket (4) is provided between the cylinder body (1) and the cylinder head (2).

7. A diesel engine according to claim 6, characterized in that: The positioning mechanism includes a positioning pin (10), a first pin hole (11) is provided on the cylinder head (2), a second pin hole (12) is provided on the cylinder body (1), the first pin hole (11) and the second pin hole (12) are provided correspondingly, and a positioning groove (13) matching the positioning pin (10) is provided on the sealing gasket (4). The positioning pin (10) is sequentially arranged in the first pin hole (11), the positioning groove (13) and the second pin hole (12).

8. A diesel engine according to any one of claims 1-7, characterized in that: The sealing gasket (4) is made of copper. The cylinder head (2) is provided with a number of slots (8) with openings facing the sealing gasket (4) at intervals. The number of slots (8) is provided on the sealing gasket (4).

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