Engine cylinder cover sealing structure based on combination of hard sealing and elastic sealing

Abstract

The invention discloses an engine cylinder cover sealing structure based on combination of hard sealing and elastic sealing, and relates to the technical field of engine sealing. According to the technical key points, a mechanical seal (main seal) formed by two sealing joint surfaces and a flexible seal (auxiliary seal) formed by an O-shaped ring made of a flexible material are adopted, so that a main sealing structure and an auxiliary sealing structure are formed, and double barriers are formed between the cylinder cover and the cylinder body, so that slight leakage of the main seal can be avoided, and the sealing effect is improved. Therefore, the technical problems that when an existing engine sealing structure is used, the sealing effect is not stable, and faults are prone to occurring due to single sealing are effectively solved, effective sealing between the cylinder body and the cylinder cover is achieved, and the service life of the engine is prolonged. And the operation safety and robustness of the engine are greatly improved while the sealing effect is improved.

Description

Technical Field

[0001] This invention relates to the field of engine sealing technology, and in particular to an engine cylinder head sealing structure based on a combination of hard seals and elastic seals. Background Technology

[0002] An engine is a machine that converts other forms of energy into mechanical energy, including reciprocating piston engines. The term "engine" can refer to both power-generating devices and the entire machine including the power unit. The engine block forms the engine's skeleton and serves as the mounting base for all its mechanisms and systems. Its sealing devices are generally divided into radial seals and axial seals. This type of sealing structure typically uses O-rings installed in grooves for sealing. This method separates the radial and axial O-rings for installation. While this method ensures a good seal, it requires squeezing the O-rings to fit them into the mounting holes or grooves. During this process, the O-rings are easily damaged by friction against the sealing surface, resulting in a loss of sealing performance.

[0003] Currently, a Chinese patent application with patent number "CN202422266379.2" discloses a sealing structure for the cylinder body and cylinder head of an air compressor. The structure includes a cylinder body, cylinder head, bolts, and an O-ring. The lower end of the cylinder head is inserted into a groove in the cylinder body, and the cylinder head and cylinder body are fastened together by bolts. The inner bore of the cylinder body has a chamfer A with a triangular cross-section, and an O-ring is embedded in chamfer A. The inner diameter of the O-ring is smaller than the outer diameter of the lower end of the cylinder head, and the outer diameter of the O-ring extends to the outside of the inner bore of the cylinder body. This sealing structure is located at the junction of the cylinder body and cylinder head. During installation, the gap of the chamfer, combined with the elastic deformation of the O-ring, achieves a sealing effect.

[0004] However, during the implementation of the above technical solution, at least the following technical problems were discovered:

[0005] The sealing effect is unstable and single seals are prone to failure: Existing technologies mostly use a single cylinder head gasket seal or a simple O-ring seal. Under extreme conditions of high boost and high heat load, a single seal structure has inherent defects. Once the seal fails, it will directly lead to serious failures such as reduced engine power and coolant or engine oil contamination, lacking safety redundancy. This is especially evident for commercial vehicles, construction machinery, and special engines with extremely high reliability requirements. Secondly, existing sealing structures are mostly divided into two types. One is the flexible seal mentioned above, which uses a sealing structure made of flexible material. By placing it between the cylinder block and cylinder head, the mutual compression between the two causes the flexible material to deform, thereby sealing the gap between the cylinder block and cylinder head, thus achieving a sealing effect. The other is a flow-blocking structure, which uses a flow-blocking structure at the connection between the cylinder head and cylinder block. By designing a turbulence-blocking structure to prevent airflow, gas cannot easily escape from the gap between the cylinder head and cylinder block, thus achieving a sealing effect. However, both types of seals have two significant drawbacks: first, when the sealing effect fails, the sealing function is lost, lacking a remedial structure; second, regardless of whether it is a flexible seal or a flow-blocking seal, a gap still exists between the cylinder head and cylinder block. For example, a resistance structure only achieves a seal by squeezing the cylinder head and cylinder block together, leaving a gap between them; while a flexible seal also fills the gap between the cylinder block and cylinder head with a flexible material, the gap still exists. Furthermore, the flexibility of the material itself makes it prone to deformation, and its sealing effect gradually deteriorates over time. Therefore, we propose an engine cylinder head sealing structure based on a combination of hard and elastic seals. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] To address the shortcomings of existing technologies, this invention provides an engine cylinder head sealing structure based on a combination of hard seals and elastic seals, solving the technical problems of unstable sealing performance and susceptibility to failure when using existing engine sealing structures with only one seal.

[0008] (II) Technical Solution

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] An engine cylinder head sealing structure based on a combination of hard and elastic seals is disposed between the engine cylinder head and the cylinder block. The sealing structure includes:

[0011] The first sealing component installed on the cylinder head is a flexible seal, which is sealed by the compression of the first sealing component by the cylinder head and the cylinder block;

[0012] The second sealing component, located at the connection between the cylinder head and the cylinder block, is a hard seal that achieves sealing through the mutual contact between the cylinder head and the cylinder block.

[0013] Preferably, the first sealing component is an O-ring made of flexible material, which is disposed on the inner wall of the cylinder head; when the cylinder body and the cylinder head are mated, the O-ring fits against the mating pipe surface on the cylinder body.

[0014] Preferably, the second sealing component is a sealing mating surface provided on the end face of the connecting pipe and the inner wall of the cylinder head, and the sealing mating surface is provided with asymmetrical ring patterns; when the cylinder body and the cylinder head are connected, the asymmetrical ring patterns at corresponding positions of the connecting pipe and the cylinder head fit together.

[0015] Preferably, the sealing structure further includes:

[0016] A third sealing assembly is provided between the connecting pipe and the cylinder head. Two sets of the third sealing assembly are provided, one on the connecting pipe and the other on the cylinder head.

[0017] The third sealing assembly includes a hot melt medium and a heating element. The hot melt medium is wrapped around the heating element and is connected to the connecting pipe and the cylinder head respectively. When the connecting pipe and the cylinder head are connected, the hot melt medium is heated to melt by the heating element, and the two sealing assemblies are fused together after melting.

[0018] Preferably, both the outer wall of the connecting pipe and the inner wall of the cylinder head are provided with annular embedding grooves to provide space for the hot melt medium and the heating element. When the connecting pipe and the cylinder head are connected, the two embedding grooves correspond to each other.

[0019] Preferably, the inner walls of both embedded grooves are provided with two rows of inner lining strips, and the two rows of inner lining strips extend outward in opposite directions, thereby fixing the hot melt medium through the two rows of inner lining strips.

[0020] Preferably, the heating element includes an annular heating wire, which is divided into two groups: one group is a heating wire 1 disposed on the inner wall of the cylinder head, and the other group is a heating wire 2 disposed on the outer wall of the connecting pipe. The heating wire can heat the hot melt medium to a molten state.

[0021] Preferably, a copper sheet one is embedded in the outer wall of the connecting pipe, and a copper sheet two is embedded in the inner wall of the cylinder head, and the copper sheet one and the heating wire two are connected by wires as well as the copper sheet two and the heating wire one.

[0022] Specifically, when the connecting pipe and the cylinder head are connected, the copper sheet one on the outer wall of the connecting pipe is in contact with the copper sheet two on the inner wall of the cylinder head.

[0023] Preferably, a conductive sheet is provided on each side of the cylinder head, and the conductive sheet is connected to the first heating wire through a wire. When the two conductive sheets are energized, the current can enter the first heating wire and the second copper sheet through the conductive sheet, and then be transmitted from the second copper sheet to the first copper sheet, and then from the first copper sheet to the second heating wire.

[0024] (III) Beneficial Effects

[0025] 1. By employing a mechanical seal (main seal) formed by two sealing surfaces and a flexible seal (auxiliary seal) formed by an O-ring made of flexible material, a dual sealing structure is formed, creating a double barrier between the cylinder head and cylinder block. This allows the auxiliary seal to effectively intercept even minor leaks in the main seal. Therefore, it effectively solves the technical problems of unstable sealing performance and susceptibility to failure of single seals in existing engine sealing structures. This achieves effective sealing between the cylinder block and cylinder head, improving the sealing effect while greatly enhancing the engine's operational safety and robustness.

[0026] 2. By installing a set of heating wires with a hot melt medium on both the cylinder head and the cylinder block, the hot melt medium can be heated to melt by electric heating. When the cylinder block and cylinder head are joined, the two sets of hot melt medium correspond to each other. This allows for simultaneous heating and melting of the two hot melt mediums, followed by cooling and solidification to form a dense filling material between the cylinder block and cylinder head. This improves the sealing effect between the cylinder head and cylinder block. Furthermore, this characteristic allows for periodic maintenance of the seal through periodic heating, thereby significantly improving the sealing effect and stability. Attached Figure Description

[0027] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0028] Figure 1 This is an overall structural diagram of the engine in an embodiment of the present invention;

[0029] Figure 2 This is a cross-sectional view of the cylinder block and cylinder head in an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the connection between the cylinder head and the cylinder block in an embodiment of the present invention;

[0031] Figure 4 This is a cross-sectional view of the third sealing assembly in a split state in an embodiment of the present invention;

[0032] Figure 5This is a cross-sectional view of the third sealing assembly in the combined state in an embodiment of the present invention;

[0033] Figure 6 This is a structural diagram of the internal heating element of the cylinder head in an embodiment of the present invention;

[0034] Figure 7 This is a diagram showing the docking structure of the two sets of heating elements in an embodiment of the present invention;

[0035] Figure 8 This is a partial schematic diagram of the docking of two sets of heating elements in an embodiment of the present invention.

[0036] Legend:

[0037] 11. Cylinder head; 12. Connecting groove; 13. Connecting pipe;

[0038] 2. Cylinder block;

[0039] 3. Sealing of the mating surfaces;

[0040] 4. O-rings;

[0041] 51. Heating wire one; 52. Heating wire two; 53. Hot melt medium; 54. Inner lining strip; 55. Copper sheet one; 56. Copper sheet two; 57. Wire;

[0042] 6. Conductive sheet. Detailed Implementation

[0043] This application provides an engine cylinder head sealing structure based on a combination of hard and elastic seals. This effectively solves the technical problems of unstable sealing performance and susceptibility to failure of single seals in existing engine sealing structures. In the use of existing engine sealing structures, a mechanical seal (main seal) formed by two sealing surfaces and a flexible seal (auxiliary seal) formed by an O-ring made of flexible material are used to form a main and auxiliary sealing structure. This creates a double barrier between the cylinder head and the cylinder block, so that even if the main seal leaks slightly, the auxiliary seal can effectively intercept it. This achieves effective sealing between the cylinder block and the cylinder head, improving the sealing effect and greatly enhancing the engine's operational safety and robustness.

[0044] Example 1: The technical solution in this application example effectively solves the technical problem that the sealing effect of the existing engine sealing structure is unstable and prone to failure when using a single seal. The overall idea is as follows:

[0045] To address the problems existing in the prior art, this invention provides an engine cylinder head sealing structure based on a combination of hard and elastic seals, disposed between the engine cylinder head 11 and the cylinder block 2. This sealing structure mainly comprises a mechanical seal, a flexible seal, and a remolded seal. Firstly, the mechanical seal utilizes the bolted connection between the cylinder block 2 and the cylinder head 11 to seal the gap between their contact surfaces. Compared to the traditional smooth treatment of the connection between the cylinder block 2 and the cylinder head 11, we employ a non-smooth structure, i.e., the contact surfaces of the cylinder block 2 and the cylinder head 11 have asymmetrical textures. When the cylinder head 11 and cylinder block 2 are joined, their contact surfaces are not on the same plane (the contact surfaces are irregular). Therefore, air or other substances attempting to pass through the contact surfaces will encounter resistance, preventing air or impurities from passing through, thus sealing the cylinder head 11 and cylinder block 2. Secondly, flexible sealing utilizes the compressive force generated when the cylinder head 11 and cylinder block 2 are joined. A sealing structure made of flexible material covers the contact area between the two. When the cylinder head 11 and cylinder block 2 are joined together, the compressive force acts on the flexible material, causing it to deform. The flexible material should... Under the action of force, it expands, thus tightly fitting with the cylinder head 11 and cylinder block 2, thereby achieving a sealing effect. This is also the most commonly used sealing method on the market. The difference is that we use a mechanical structure as the main sealing structure, supplemented by a flexible seal as an auxiliary sealing structure, thus forming a unified whole. Thirdly, reconstructed sealing is our main technical improvement. Its principle utilizes the properties of materials, namely thermal fusion. Materials melt when heated and then re-solidify upon cooling, such as paraffin wax and plastics. Based on this, seals are designed at the connection points of the cylinder head 11 and cylinder block 2. A heating structure and hot-melt material are placed on top. After the cylinder head 11 and cylinder body 2 are joined, the hot-melt material is heated to melt through the heating structure, thereby fusing the hot-melt material on the cylinder head 11 with the hot-melt material on the cylinder body 2. In this liquid state, the hot-melt material can fill the gap between the cylinder head 11 and the cylinder body 2 under its own flow properties. After it solidifies, it reforms into a solid, thus sealing the gap between the cylinder head 11 and the cylinder body 2. Furthermore, this characteristic can be used to reconstruct the sealing structure by periodically heating the hot-melt material. The specific structure is as follows:

[0046] A mechanical seal, in combination with a flexible seal, forms a combined seal, with the mechanical structure serving as the primary sealing structure. This structure is located at the mating point between the cylinder head 11 and the cylinder body 2. Figure 2 and Figure 3As shown, it mainly consists of two interlocking sealing surfaces 3. The first is located at the end of the cylinder body 2, where the cylinder body 2 inserts into the cylinder head 11, i.e., the connecting pipe 13, with the sealing surface 3 located on the end face of the connecting pipe 13 facing the cylinder head 11. The second is located in the groove corresponding to the connecting pipe 13 in the cylinder head 11, i.e., the mating groove 12, with the sealing surface 3 positioned corresponding to the end face of the connecting pipe 13, as shown below. Figure 3 As shown, both sealing surfaces 3 are asymmetrical annular patterns, such as wavy patterns. When the cylinder body 2 is connected to the cylinder head 11, the asymmetrical annular patterns at the corresponding positions of the connecting pipe 13 and the cylinder head 11 will fit together. At this time, the gap at the connection between the cylinder head 11 and the cylinder body 2 is not on the same plane, but forms uneven textures. When the air or medium moves along the sealing surface 3, the flow speed of the air or medium is continuously reduced under the action of its uneven textures, thereby playing a sealing role. This structure belongs to the hard seal of metal.

[0047] A flexible seal, based on a mechanical seal, further restricts the outflow of air or media from the gap between the cylinder head 11 and the cylinder body 2. It primarily utilizes the compressive force between the cylinder head 11 and the cylinder body 2 as the sealing force. The principle involves using an O-ring 4 made of flexible material, placed on the inner wall of the cylinder head 11. Only in this way can the O-ring 4 be positioned between the cylinder head 11 and the cylinder body 2 when the cylinder body 2 is mated with it. The force generated by fixing the cylinder head 11 and the cylinder body 2 with bolts then compresses the O-ring 4, causing it to deform. At this time, the elastic material, under its own internal stress, compresses the cylinder head 11 and... The cylinder head 11 moves within the gap between the cylinder block 2, thereby blocking the gap between the cylinder head 11 and the cylinder block 2, thus completing the seal between the cylinder head 11 and the cylinder block 2. In addition, by cooperating with the mechanical seal, a stable seal is formed, so that even if there is a slight leakage in the main seal (mechanical seal), the auxiliary seal (flexible seal) can also effectively intercept it. Therefore, it effectively solves the technical problems of unstable sealing effect and easy failure of single seal in the use of existing engine sealing structure. Thus, it achieves effective sealing between the cylinder block 2 and the cylinder head 11, improving the sealing effect while greatly improving the engine's operating safety and robustness.

[0048] Example 2: Based on Example 1, this embodiment of the application provides a set of heating wires with a hot melt medium 53 on both the cylinder head 11 and the cylinder body 2. The hot melt medium 53 can be heated to melt by electric heating. When the cylinder body 2 and cylinder head 11 are joined, the two sets of hot melt media 53 correspond to each other. This allows for simultaneous heating and melting of both hot melt media 53, followed by cooling and solidification to form a dense filling material between the cylinder body 2 and cylinder head 11. This improves the sealing effect between the cylinder head 11 and cylinder body 2. Furthermore, this characteristic allows for periodic maintenance of the seal through periodic heating, thereby significantly improving the sealing effect and stability. The overall concept is as follows:

[0049] Reconstructing the seal is our main technical improvement. The principle is to utilize the properties of materials, namely their thermal fusion. Materials melt when heated and then solidify again after cooling, such as paraffin wax and plastic. Based on this, heating structures and thermal fusion materials are set at the connection between the cylinder head 11 and the cylinder body 2. After the cylinder head 11 and the cylinder body 2 are joined, the thermal fusion material is heated to melt by the heating structure, so that the thermal fusion material on the cylinder head 11 and the thermal fusion material on the cylinder body 2 are fused together to form a new and dense sealing structure.

[0050] Similar to the mechanical seal structure, it mainly consists of two parts, which are respectively installed on the connecting pipe 13 and the cylinder head 11, such as... Figure 4 and Figure 5 As shown, both have a heat-melting medium 53 and a heating element for heating the heat-melting medium 53. In order to stably conduct heat to the heat-melting medium 53, the heat-melting medium 53 is wrapped around the heating element. This allows the heat-melting medium 53 to be heated to melt during the docking of the connecting pipe 13 and the cylinder head 11, providing a basis for subsequent fusion and solidification. To avoid affecting the docking between the cylinder head 11 and the cylinder body 2, we have annular embedding grooves on the outer wall of the connecting pipe 13 and the inner wall of the cylinder head 11 to provide space for the heat-melting medium 53 and the heating element. In order to maintain the docking of the two heat-melting media 53, the two embedding grooves need to correspond to each other when the connecting pipe 13 and the cylinder head 11 are docked, as shown in the figure. Figure 4 and Figure 5 The diagram shown is for reference only, so that when the hot melt medium 53 is heated, the hot melt medium 53 on the cylinder head 11 and the cylinder body 2 can be fused together;

[0051] However, a new problem arises: how to maintain the stable connection between the hot melt medium 53 and the cylinder body 2 and cylinder head 11. We installed two rows of corresponding upper and lower inner lining strips 54 on the inner walls of both embedding grooves, such as... Figure 4 and Figure 5As shown in the enlarged view, the two rows of inner lining strips 54 extend outward in opposite directions, so that the solidified hot melt medium 53 can be well fixed in the embedding groove. The inside of the embedding groove is also frosted to facilitate the filling of the melted hot melt medium 53. In this way, it can be stably fixed in the embedding groove after solidification.

[0052] The heating element is divided into two parts, which heat the molten medium 53 in the cylinder body 2 and cylinder head 11 respectively. The main component is an electric heating wire that heats up when energized. One set consists of heating wire 51 installed on the inner wall of the cylinder head 11, and the other set consists of heating wire 52 installed on the outer wall of the connecting pipe 13. This allows the molten medium 53 to be heated to a molten state by controlling the heating wires. However, since the heating wires are embedded in the groove and not connected to the outside, and the two heating wires need to operate synchronously (i.e., simultaneously turning on and off), the heating of both sets of heating wires can be accomplished using a single power supply structure. Therefore, we first embed two sets of copper plates 55 on the outer wall of the connecting pipe 13, opposite to the copper plates 56 embedded on the inner wall of the cylinder head 11. That is, when the connecting pipe 13 and cylinder head 11 are connected, the copper plates on the outer wall of the connecting pipe 13... The first heating element 55 is attached to the second heating element 56 on the inner wall of the cylinder head 11. The first heating element 55 and the second heating element 52, as well as the second heating element 56 and the first heating element 51, are connected by wires 57. In this way, only one heating element needs to be powered, and the current can flow through the wires 57 to the other heating element, thus providing power synchronously. Since the cylinder head 11 is an external structure and is close to the outer shell, two conductive plates 6 that can carry positive and negative current are set on its exterior. The conductive plates 6 are connected to the first heating element 51 through the wires 57. Thus, when the two conductive plates 6 are energized, the current can enter the first heating element 51 and the second heating element 56 through the conductive plates 6, and then be transmitted from the second heating element 56 to the first heating element 55, and then from the first heating element 55 to the second heating element 52, thereby simultaneously powering the first heating element 51 and the second heating element 52, causing them to melt.

[0053] In the specific implementation process, the connecting pipe 13 on the cylinder body 2 is first inserted into the mating groove 12 of the cylinder head 11, and then the two are fixed together with bolts. Then, an external battery supplies power to the heating wires inside the cylinder head 11 and the cylinder body 2. The positive and negative terminals of the external power supply are connected to two conductive plates 6 respectively. At this time, the current flows through the external battery into the conductive plate 6 connected to it. Since the conductive plate 6 is connected to the copper sheet 55 and the heating wire 51 through the wire 57, and the cylinder head 11 and the cylinder body 2 are connected... Afterwards, copper sheet 55 and copper sheet 56 are bonded together. Therefore, the current in the conductive sheet 6 not only supplies power to heating wire 51 but also passes through copper sheet 56 to copper sheet 55, and through copper sheet 55 to heating wire 52, thus simultaneously supplying power to both heating wire 51 and heating wire 52. The hot melt medium 53, fitted around the heating wire, melts under the influence of the high temperature of the heating wire, forming a liquid state. Since the hot melt medium 53 on the cylinder head 11 and cylinder body 2 correspond to each other after docking, as... Figure 5 As shown, when the hot melt medium 53 melts, the hot melt medium 53 inside both fuses together and fills every gap between the cylinder body 2 and the cylinder head 11 in a liquid state, thereby blocking the gap between the cylinder head 11 and the cylinder body 2. After solidification, it forms a whole and is stably connected between the cylinder head 11 and the cylinder body 2, which can not only achieve a sealing effect but also strengthen the firmness between the two. Conversely, during disassembly, the cylinder head 11 and the cylinder body 2 can be separated by heating until it melts, while the hot melt medium 53 is in a melted state.

[0054] Example 3: Based on Example 2, this application provides a method for testing the sealing performance of an engine cylinder head sealing structure. The overall concept is as follows:

[0055] 1. Overall inspection:

[0056] This testing method is applicable to engine cylinder head composite sealing structures integrating flexible seals, hard seals, and hot-melt seals. It is compatible with cylinder heads made of various materials such as cast aluminum and cast iron, but not suitable for cylinder head sealing structures with a single seal type. This method effectively solves the core pain points of existing technologies in terms of working condition adaptability, testing accuracy, and fault location. The overall process is divided into six core steps, and the core responsibilities and operational requirements of each step are clearly defined as follows: Assembly fixing and stress elimination are the core of establishing a stable and unified testing benchmark to avoid the impact of assembly errors and stress interference on the testing results; Differentiated monitoring system construction and temperature drift compensation require the construction of a dedicated monitoring system based on the characteristics of different sealing components to eliminate testing deviations caused by temperature fluctuations; Data acquisition and interference elimination aim to accurately obtain complete testing data to provide reliable data support for subsequent analysis and judgment; Hot-melt seal curing and working condition simulation are used to restore the actual working state of the hot-melt seal components to ensure that the testing results are highly consistent with the engineering application scenario; Secondary testing and leakage analysis and location accurately identify leakage problems and specific locations through comparative analysis of two testing data; Sealing performance judgment and rectification are responsible for scientifically judging the testing results, forming a closed-loop management mechanism from testing, judgment, rectification to verification.

[0057] Before the process can be implemented, four prerequisites must be met: sealing structure, equipment, personnel and environment, and preliminary verification. Each of these conditions is a necessary foundation for ensuring the standardized and efficient conduct of the testing work. The implementation process must strictly follow the following specifications:

[0058] During the precondition confirmation phase, the sealing structure must be a modular design, and each component must meet specific technical requirements. The flexible sealing component uses fluororubber O-rings with a tensile strength of not less than 15MPa, high temperature resistance up to 200℃, and a volume change rate of no more than 5% after 24 hours of immersion in engine oil. The hard sealing component uses cast aluminum ADC12 or cast iron HT250 material for the sealing surface, with a nitrided layer thickness controlled at 0.1-0.2mm after nitriding treatment, a hardness HV of not less than 500, and a flatness error of ≤0.02mm / 100mm. The hot-melt sealing component consists of a nickel-chromium alloy heating wire (80% nickel, 20% chromium) and a modified polyamide hot-melt medium. The heating wire has a resistance of 10-20Ω / m at 20℃, the hot-melt medium has a melting temperature of 180-220℃, and a bonding strength with the cylinder block of not less than 5MPa. All sealing components must be free from defects such as deformation, breakage, and misalignment after assembly.

[0059] Regarding equipment, all testing equipment must be within its calibration validity period, with a calibration cycle of ≤1 year, and the core parameters must meet the following requirements:

[0060] The temperature control chamber has a temperature control accuracy of ±1℃ and a temperature range covering -40℃ to 400℃; the high-precision torque wrench has a range of 0-200 N·m and an accuracy of ±1 N·m; the pressure sensor has an accuracy of ±0.01 MPa; and the fluorescence detector has a detection accuracy of ≥10.-9 g / s; Infrared thermal imaging monitoring module temperature measurement accuracy ±0.5℃; Temperature adaptive pressure compensation module compensation accuracy ≤0.1%FS; Data acquisition and analysis system supports a sampling frequency of 1 time / second, with built-in digital filtering and multi-physics coupling algorithms; Regarding personnel and environmental conditions, operators must have a background in mechanical engineering or automotive testing, and can only work after passing professional training and assessment; The testing site must be kept clean and dry, with the ambient temperature controlled between 15-30℃, fluctuation ≤±2℃, and relative humidity between 40-60%, fluctuation ≤±5%RH, away from strong vibration sources, and equipped with complete ventilation facilities and emergency equipment; A special verification form must be filled out during the preliminary verification. Each of the above conditions must be verified one by one. Only after verification and confirmation by the verification personnel can the testing work be started. Each step must be implemented in strict accordance with the following specifications: During the assembly and stress relief stage, the cylinder head and cylinder body are connected according to the design benchmark. The bolts are tightened in three stages by gradually increasing the pressure using the principle of diagonal uniform tightening. The preset torque for cast aluminum cylinder heads is 80-100 N·m, and the preset torque for cast iron cylinder heads is 100-120 N·m. After tightening, the sealing surface gap is checked with a feeler gauge with an accuracy of 0.01 mm to ensure that the gap is ≤0.02 mm. At the same time, the conduction resistance of the hot melt circuit is tested with a multimeter to ensure that the resistance is ≤5 Ω and the deviation between two repeated tests is ≤0.5 Ω.

[0061] The assembly was then placed in a temperature-controlled test chamber and kept at 25±5℃ for 30 minutes to eliminate assembly stress. Core parameters such as torque, clearance, resistance, and temperature were recorded throughout the process. The next stage involved setting up a differentiated monitoring system and compensating for temperature drift. This required preparing dry nitrogen for the hard-seal area and fluorescent tracer gas for the flexible-seal area, with a fluorescent agent concentration of 0.1-0.2 g / L. The detection medium was then introduced into the corresponding areas, with the pressure in the hard-seal area adjusted to 0.5-0.7 MPa and the pressure in the flexible-seal area adjusted to 0.2-0.4 MPa. The pressure sensor, fluorescent detector, and infrared thermal imaging module were arranged according to specifications. After zero-point calibration, the temperature adaptive pressure compensation module was activated. The compensation formula was: P_compensation = P_preset × [1 + 0.0006 × (T_actual - T_standard)]. The module was then adjusted until all monitoring signals stabilized.

[0062] During the data acquisition and interference removal phase, the pressure of the detection medium must be kept stable. High-pressure media should be stabilized for 8-10 minutes, and low-pressure media for 5-8 minutes. Pressure, fluorescence intensity, and temperature data should be collected synchronously at a frequency of 1 time / second. Interference signals such as environmental vibration should be removed using a digital filtering algorithm to construct a three-dimensional monitoring dataset. After verifying the data validity, a backup should be exported, and the file naming must conform to specifications and be traceable. During the hot-melt sealing and curing and operating condition simulation phase, a 12-24VDC power supply should be connected to heat the hot-melt medium to 180-220℃ and hold it at that temperature for 5-10 minutes. Simultaneously, a temperature-controlled test chamber should be used to simulate the high-temperature operating conditions of an engine: 260℃±5℃ for cast aluminum cylinder heads and 380℃±5℃ for cast iron cylinder heads. After holding at constant temperature and pressure for 30 minutes, the medium should be cooled to room temperature at a rate of 5℃ / minute and allowed to stand for another 20 minutes to ensure complete curing. After removing the assembly, the hardness of the hot-melt medium should be tested using a Shore D hardness tester to ensure that the hardness is controlled within the range of 60-70. Secondary testing and leakage analysis are then conducted. The system must be built, temperature drift compensation and data acquisition and interference removal processes must be strictly repeated to ensure that the testing conditions are consistent for both tests. By comparing the two 3D monitoring datasets, the changes in pressure decay, leakage, fluorescence intensity and temperature distribution are analyzed. The leakage type is distinguished by a multiphysics coupling algorithm: linear decay indicates gap leakage, and exponential decay indicates porous leakage. The faulty sealing component and leakage location are accurately located. The sealing performance judgment and rectification must be carried out based on multi-dimensional indicators. The qualified standards include no visible leakage, leakage ≤0.01mL / min, pressure decay ≤5%, and no abnormalities in fluorescence and temperature signals. If all indicators meet the standards, it is judged as qualified, a test report is issued and archived in a standardized manner. If it does not meet the standards, a special rectification plan must be formulated for the specific causes such as improper bolt torque, O-ring aging, and insufficient heat fusion sealing. After the rectification is completed, the whole process test is re-executed until all indicators are qualified. All test, judgment and rectification data are archived according to the principle of one file per machine to ensure full traceability.

[0063] 2. Testing media and compatibility standards:

[0064] This specification addresses two types of detection media: dry nitrogen for hard-sealed areas and fluorescent tracer gas for flexible-sealed areas. It clarifies their composition, purity, pressure compatibility, usage, and testing standards, with specific requirements as follows:

[0065] Before implementation, three core prerequisites must be met: First, the purchased testing media must be accompanied by supplier material certificates and qualification certificates, and the supplier must possess valid industry qualifications; second, specialized testing equipment such as dew point meters, oil content analyzers, fluorescence concentration analyzers, and ion chromatographs must be provided, and all equipment must be within the calibration validity period; third, testing personnel must possess relevant chemical testing qualifications and pass professional training and assessment before conducting testing work; For the dedicated dry nitrogen in the hard-sealed area, the following specifications must be strictly followed: 10% of each batch must be sampled before warehousing, and purity must be verified using gas chromatography; the dew point must be ≤-40℃, and each bottle must be tested before use; if it exceeds the standard, it must be discharged for 30 seconds and then retested; the oil content must be ≤0.01mg / m³. 3 Three cylinders are randomly selected from each batch for testing; the pressure range is 0.5-0.7MPa, with 0.6MPa preferred for cast aluminum cylinder heads and 0.65MPa preferred for cast iron cylinder heads. The pressure adjustment rate is ≤0.05MPa / s, and the cylinders can only be put into use after stabilizing for 30 seconds and the fluctuation is ≤±0.005MPa; during use and storage, 316L stainless steel pipes must be used for connection to ensure that the pipes are undamaged and leak-free; when using, strictly follow the operating procedure of opening the cylinder valve first and then adjusting the pressure reducing valve, and reverse operation is strictly prohibited; store in a dedicated cylinder cabinet, away from fire and heat sources, with an ambient temperature ≤30℃, and the cylinders must be firmly fixed to prevent impact and exposure to sunlight; during use, a special record form must be filled out to record key information such as purchase, inspection, and use in detail, and archived in accordance with the requirements.

[0066] The fluorescent tracer gas composition for flexible sealing areas must meet the following standards: The main component is compressed air, with 20.95% oxygen, 78.08% nitrogen, and 0.97% other inert gases. The fluorescent tracer uses naphthalimide dyes, with a concentration controlled between 0.1-0.2 g / L, preferably 0.15 g / L. The concentration must be tested before each bottle is used. Chloride and sulfate ion content must be ≤0.001 mg / m³. Three bottles are randomly selected from each batch for verification using ion chromatography. The pressure range is 0.2-0.4 MPa, and cast aluminum cylinder heads are preferred. Use 0.3MPa, with 0.35MPa preferred for cast iron cylinder heads. The pressure adjustment rate should be ≤0.02MPa / s. The pressure should be stabilized for 30 seconds with fluctuations ≤±0.005MPa before use. Shake the gas cylinder for 5 minutes before use to ensure uniform dispersion of the fluorescent tracer. Use corrosion-resistant hoses for connection, and check for leaks before venting. Ventilation facilities must be turned on during use, and residual gas must be discharged through ventilation ducts after use. Direct discharge into the operating area is strictly prohibited. Storage specifications are the same as for dry nitrogen. Detailed records of relevant information must be kept and properly archived during use.

[0067] 3. Differentiated monitoring system and calibration:

[0068] This specification clarifies the constituent modules, calibration requirements, layout specifications, and signal processing standards of the differentiated monitoring system. It is designed to be integrated with the system setup and temperature drift compensation procedures, aiming to ensure detection accuracy and address issues such as cluttered monitoring systems, incomplete calibration, and non-standard signal processing in existing technologies. Specific requirements are as follows:

[0069] The system consists of a pressure sensor, a fluorescence detector, an infrared thermal imaging monitoring module, and a temperature-adaptive pressure compensation module. These four modules work together to accurately acquire pressure, fluorescence, and temperature signals and compensate for temperature drift. The core requirements for system operation include:

[0070] Calibration work must consider both periodic calibration and pre-use calibration to ensure stable module performance; module layout must be adapted to the monitoring scenario to ensure accurate and interference-free signal acquisition; targeted algorithms should be used to process the signals to ensure data validity; the following prerequisites must be met before implementation:

[0071] Equipped with special calibration equipment such as pressure calibrators, fluorescence standard sources, and infrared temperature measurement calibrators, and all equipment is within the calibration validity period; calibration personnel must have metrological verification qualifications and be qualified after professional training and assessment; the appearance of all monitoring modules is intact, the circuit connections are normal, and they are within the calibration validity period. It is strictly prohibited to use expired or uncalibrated or damaged modules; module calibration must strictly follow the following specifications: The pressure sensor is regularly calibrated once every 6 months. Zero calibration needs to be completed before use. The calibration points are set at 0 MPa, 0.3 MPa, 0.6 MPa, and 1.0 MPa. An error ≤ ±0.01 MPa is considered qualified; the fluorescence detector is regularly calibrated once every 3 months. Zero calibration needs to be completed before use. Align it with a 0.15 g / L fluorescence standard source, the detection distance is 10 mm. A display value deviation ≤ ±5% and a light transmittance of the filter at a wavelength of 500 - 600 nm ≥ 95% are considered qualified; the infrared thermal imaging monitoring module is regularly calibrated once every 6 months. Temperature measurement error calibration needs to be completed before use. The calibration points are set at 50 °C, 100 °C, 200 °C, and 300 °C. A temperature measurement error ≤ ±0.5 °C and clear imaging are considered qualified; the temperature adaptive pressure compensation module is regularly calibrated once every 3 months. Compensation accuracy calibration needs to be completed before use. Simulate environmental temperatures of 20 °C, 25 °C, and 30 °C. A deviation between the compensation value and the theoretical value ≤ 0.1% FS is considered qualified; after all modules are calibrated qualified, a calibration record form needs to be filled out and a calibration label needs to be pasted. Unqualified modules need to be repaired or replaced in a timely manner; the module layout and signal processing must follow the following specifications: The pressure sensors are symmetrically arranged at the inlet and outlet of the medium, the probes are perpendicular to the direction of the medium flow, and the distance from the sealing surface is 15 mm; 4 fluorescence detectors are evenly arranged around the O-ring mating surface with a spacing of 50 mm. The probes are aligned with the sealing gap and are at 90° to the sealing surface to avoid direct light source interference; the infrared thermal imaging module is arranged directly above the hot melt sealing component, 50 mm from the sealing surface, ensuring that the entire hot melt sealing area is covered; all lines need to be uniformly sorted and fixed to avoid interfering with operations and signal transmission; in terms of signal processing, the pressure signal uses a 0.8 Hz digital filtering algorithm with a resolution of 0.001 MPa; the fluorescence intensity signal uses a peak extraction algorithm with a resolution of 0.01 cd / m 2 ; the temperature signal uses a 3-point average filtering algorithm with a resolution of 0.1 °C; all signals are synchronously collected according to the time stamp, and the synchronous error ≤ 0.1 s to ensure consistent time matching; after the system is debugged qualified, fill out the debugging record form and have it signed and confirmed by the technical person in charge before starting the data acquisition work.

[0072] 4. Hot melt seal curing and working condition simulation:

[0073] This specification aims at the detection work of the hot melt medium before the cylinder head and cylinder block are butted, clarifies the stage division, parameter standards, and verification requirements of the entire process of hot melt seal curing, accurately restores the actual working state of the hot melt seal assembly, ensures the authenticity of the detection results, and is executed in conjunction with the steps of hot melt seal curing and working condition simulation. The specific requirements are as follows:

[0074] The whole process of hot-melt sealing curing and working condition simulation is divided into three stages: heating, high-temperature working condition simulation, and cooling and curing. The parameters of each stage are strictly set according to the actual working scenario of the engine, effectively solving the problems such as chaotic simulation parameters and insufficient fitting degree with the actual working conditions in the existing technology, and providing reliable technical support for the determination of sealing performance; the following prerequisite conditions need to be met before implementation: the hot-melt component (heating wire + hot-melt medium) is installed in place without looseness or deviation, the heating wire circuit is connected normally without damage, and the hot-melt medium is filled evenly without bubbles; the temperature control test chamber is calibrated qualified, supporting uniform heating and cooling, with a rate deviation ≤ ±0.5 °C / min and a temperature control accuracy of ±1 °C; the infrared thermal imaging module and the thermocouple thermometer are both within the calibration validity period to ensure accurate temperature monitoring; the implementation of each stage needs to strictly follow the following specifications: in the heating stage, connect the 12-24VDC power supply (preferably with a power of 80W), set the heating temperature to 180-220 °C, and preferably use 200-210 °C for the modified polyamide PA66 material. The heating duration is 5-10 minutes, preferably 8 minutes for the cast aluminum cylinder head and 10 minutes for the cast iron cylinder head.

[0075] During the heating process, use the infrared thermal imaging module to record the temperature of the hot-melt medium every 2 minutes to ensure that the temperature fluctuation ≤ ±3 °C. At the same time, confirm through the observation window that the medium is in a uniform liquid state without bubble carbonization. If the temperature fluctuation exceeds the standard or the medium carbonizes, heating needs to be stopped immediately and checked and rectified; in the high-temperature working condition simulation stage, set the simulation temperature according to the high-temperature upper limit of the engine, 260 °C ± 5 °C for the cast aluminum cylinder head and 380 °C ± 5 °C for the cast iron cylinder head. Heat up at a rate of 10 °C / minute, with a rate deviation ≤ ±0.5 °C / min. After the heating is completed, keep the temperature constant and maintain the pressure for 30 minutes.

[0076] During the constant temperature process, record the surface temperature of the cylinder head once every 5 minutes to ensure that the temperature difference ≤ 5 °C. At the same time, maintain the stability of the detection medium pressure, with a fluctuation ≤ ±0.005 MPa, to avoid the influence of pressure fluctuation on the simulation effect; in the cooling and curing stage, cut off the power supply of the heating wire and cool down at a rate of 5 °C / minute, with a rate deviation ≤ ±0.5 °C / min. After cooling to room temperature (25 ± 5 °C), continue to stand for 20 minutes to ensure that the hot-melt medium is completely cured; after taking out the assembly, use a Shore D hardness tester to detect the hardness of the hot-melt medium, which needs to be controlled within the range of 60-70, and use a tensile meter to detect the bonding strength (≥ 5 MPa). If there is no peeling, crack, or deformation visually, it is qualified; the abnormal handling and recording need to be carried out in a standardized manner: when the temperature fluctuation in the heating stage exceeds the standard, immediately adjust the supply voltage and check the working status of the infrared thermal imaging module and the temperature control test chamber; when the hot-melt medium carbonizes, reduce the heating temperature by 5-10 °C, replace the medium and then reheat; when the cooling rate drops suddenly in the cooling stage, adjust the parameters of the temperature control test chamber in time to ensure the stability of the rate; all abnormal situations and handling processes need to be detailedly recorded in a special form, and after being signed and confirmed by the operator and the technical person in charge, it is archived in a standardized manner.

[0077] 5. Leakage location and remediation:

[0078] This specification addresses two core steps: secondary detection and leak analysis and location, and sealing performance assessment and rectification. It employs a multi-physics coupling algorithm combined with a multi-dimensional signal cross-validation mode to achieve precise leak location. Specific rectification plans are developed for different leak types, effectively solving pain points in existing technologies such as ambiguous location, inefficient rectification, and recurring problems. Specific requirements are as follows:

[0079] Three prerequisites must be met before implementation: First, the three-dimensional monitoring datasets for the initial and secondary inspections must be complete and valid, without missing or abnormal data, and with a synchronization error ≤0.1s; second, a complete set of leak location equipment must be provided, including an infrared thermal imaging module, a fluorescence detector, a pressure sensor, a 0.01mm precision feeler gauge, a marker pen, a high-definition camera, etc., and all equipment must be within the calibration validity period; third, dedicated rectification tools must be provided, including a high-precision torque wrench, a sealing surface grinder, sealing components of the same specification, cleaning agents, etc., to ensure the smooth progress of the rectification work.

[0080] Leak location and type determination should be performed according to a four-step process:

[0081] The first step is to extract abnormal signals by screening abnormal data from two detection datasets. The criteria for judgment are: pressure drop > 5%, leakage > 0.01 mL / min, and fluorescence intensity > 0.1 cd / m³. 2 A temperature fluctuation greater than ±1℃ is considered a leak signal if either criterion is met.

[0082] The second step is to pinpoint the leak area. Through cross-verification of multiple signals, simultaneous abnormalities in pressure and fluorescence signals correspond to leaks in flexible or hard sealing components, while simultaneous abnormalities in pressure and temperature signals correspond to leaks in thermoplastic sealing components.

[0083] The third step is to determine the type of leakage. Based on the characteristics of the leakage rate, linear decay indicates a gap leakage, which is often caused by improper bolt torque, loose sealing surface or wear. Exponential decay indicates a porous leakage, which is often caused by aging and damage of O-rings, damage of heating wires, or pores in the hot melt medium.

[0084] The fourth step is to accurately locate the leak point. For gap leaks, use a 0.01mm feeler gauge to check the gap of the sealing surface point by point. The point >0.02mm is the leak point. For multi-hole leaks, use a fluorescent detector to capture the intensity peak and combine it with infrared thermal imaging temperature hotspots for location. The positioning accuracy is controlled within ±1mm. After positioning, mark it with a marker pen and take a picture with a high-definition camera for record keeping. Targeted rectification and verification need to be implemented in categories and accurately implemented: For gap leaks caused by improper bolt torque, the torque needs to be adjusted to the appropriate range: 80-100 N·m for cast aluminum cylinder heads and 100-120 N·m for cast iron cylinder heads. Retighten according to the diagonal even principle. After tightening, check that the gap of the sealing surface is ≤0.02mm. For multi-hole leaks caused by aging and damage of O-rings, replace with fluororubber O-rings of the same specification. Before replacement, clean the groove with a cleaning agent to ensure that there are no impurities or oil stains. After replacement, check that the installation is not misaligned. For issues such as displacement and distortion, and insufficient hot-melt sealing, the curing parameters need to be optimized. The heating temperature should be 180-220℃, and the holding time should be 5-10 minutes. After replacing the hot-melt medium, the curing and working condition simulation process should be repeated. For gaps caused by wear on the hard sealing surface, the sealing surface needs to be repaired with a grinder. After grinding, the flatness should be tested to be ≤0.02mm / 100mm. If necessary, nitriding treatment should be performed again. If multiple components leak simultaneously, they should be dealt with one by one according to the principle of prioritizing core components and those that are easy to rectify, to avoid mutual interference. After rectification, the entire process test needs to be repeated to verify all qualified indicators, compare the data before and after rectification, analyze the rectification effect, and form a special rectification verification report, including the non-conformance phenomena, positioning results, rectification plan, implementation process, and effect judgment. After signing and confirmation, the report should be archived together with the original test data according to the principle of one file per machine to ensure full traceability.

[0085] Finally, it should be noted that the above embodiments are merely examples for clearly illustrating the present invention and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An engine cylinder head sealing structure based on a combination of hard seal and elastic seal, disposed between the cylinder head (11) and the cylinder block (2) of an engine, characterized in that, The sealing structure includes: The first sealing component is set on the cylinder head (11) and is a flexible seal. The seal is achieved by the compression of the first sealing component by the cylinder head (11) and the cylinder body (2). The second sealing component, which is set at the connection between the cylinder head (11) and the cylinder body (2), is a hard seal and is sealed by the mutual contact between the cylinder head (11) and the cylinder body (2).

2. The engine cylinder head sealing structure based on a combination of hard seal and elastic seal as described in claim 1, characterized in that: The first sealing component is an O-ring (4) made of flexible material, which is set on the inner wall of the cylinder head (11); when the cylinder body (2) is connected to the cylinder head (11), the O-ring (4) is in contact with the surface of the connecting pipe (13) on the cylinder body (2).

3. The engine cylinder head sealing structure based on a combination of hard seal and elastic seal as described in claim 2, characterized in that: The second sealing component is a sealing joint surface (3) provided on the end face of the connecting pipe (13) and the inner wall of the cylinder head (11), and the sealing joint surface (3) is provided with asymmetrical ring patterns; when the cylinder body (2) is connected to the cylinder head (11), the asymmetrical ring patterns at the corresponding positions of the connecting pipe (13) and the cylinder head (11) fit together.

4. The engine cylinder head sealing structure based on a combination of hard seal and elastic seal as described in claim 3, characterized in that: The sealing structure also includes: A third sealing assembly is provided between the connecting pipe (13) and the cylinder head (11), and the third sealing assembly is provided in two sets, which are respectively provided on the connecting pipe (13) and the cylinder head (11); The third sealing assembly includes a hot melt medium (53) and a heating element. The hot melt medium (53) is wrapped around the heating element and connected to the connecting pipe (13) and the cylinder head (11) respectively. When the connecting pipe (13) and the cylinder head (11) are connected, the hot melt medium (53) is heated to melt by the heating element, and the two sealing assemblies are fused together after melting.

5. The engine cylinder head sealing structure based on a combination of hard seal and elastic seal as described in claim 4, characterized in that: Both the outer wall of the connecting pipe (13) and the inner wall of the cylinder head (11) are provided with annular embedding grooves to provide space for the hot melt medium (53) and the heating element. When the connecting pipe (13) and the cylinder head (11) are connected, the two embedding grooves correspond to each other.

6. The engine cylinder head sealing structure based on a combination of hard seal and elastic seal as described in claim 5, characterized in that: The inner walls of both embedded grooves are provided with two rows of inner lining strips (54), and the two rows of inner lining strips (54) extend outward in opposite directions, thereby fixing the hot melt medium (53) through the two rows of inner lining strips (54).

7. The engine cylinder head sealing structure based on a combination of hard seal and elastic seal as described in claim 4, characterized in that: The heating element includes an annular heating wire, which is divided into two groups. One group is a heating wire 1 (51) installed on the inner wall of the cylinder head (11), and the other group is a heating wire 2 (52) installed on the outer wall of the connecting pipe (13). The heating wire can heat the hot melt medium (53) to a molten state.

8. The engine cylinder head sealing structure based on a combination of hard seal and elastic seal as described in claim 7, characterized in that: A copper sheet (55) is embedded in the outer wall of the connecting pipe (13), and a copper sheet (56) is embedded in the inner wall of the cylinder head (11). The copper sheet (55) and the heating wire (52) are connected by wires (57) as are the copper sheet (56) and the heating wire (51). When the connecting pipe (13) and the cylinder head (11) are connected, the copper sheet 1 (55) on the outer wall of the connecting pipe (13) is attached to the copper sheet 2 (56) on the inner wall of the cylinder head (11).

9. The engine cylinder head sealing structure based on a combination of hard seal and elastic seal as described in claim 8, characterized in that: A conductive sheet (6) is provided on each side of the cylinder head (11), and the conductive sheet (6) is connected to the first heating wire (51) through the wire (57). When the two conductive sheets (6) are energized, the current can enter the first heating wire (51) and the second copper sheet (56) through the conductive sheet (6), and then be transmitted from the second copper sheet (56) to the first copper sheet (55), and then from the first copper sheet (55) to the second heating wire (52).

10. A method for testing the sealing performance of an engine cylinder head sealing structure, used to test the sealing structure according to any one of claims 1 to 8, characterized in that, The steps of this detection method are as follows: Step 1: Tighten the assembled sealing structure to the cylinder head and cylinder block with the preset torque that matches the cylinder head material. Then place the assembly in a temperature control test chamber to preheat and maintain a constant temperature to eliminate assembly stress. The high temperature working condition simulation temperature, duration and cooling rate are all matched to the actual temperature change law of the engine. Step 2: Introduce a preset pressure detection medium adapted to the characteristics of different sealing areas into the cylinder, and deploy leakage monitoring devices in each key sealing area to build a multi-dimensional and comprehensive differentiated monitoring system; simultaneously activate the temperature adaptive pressure compensation mechanism. Step 3: Maintain the preset pressure stability, adapt the pressure stabilization time and sampling frequency according to the pressure level of the detected medium, collect data such as pressure, tracer signal, and temperature in real time, use filtering algorithms to remove interference signals, construct a three-dimensional monitoring dataset, and record leakage information and corresponding environmental parameters. Step 4: Power the hot melt sealing assembly to heat it, so that the hot melt medium can fully melt and fill the sealing gap; during the heating process, simulate the actual high temperature working conditions of the engine and maintain constant temperature and pressure, and then cool it down to room temperature at a preset rate; Step 5: Repeat the detection process of steps 2 to 3. The second detection conditions are the same. Use the multi-physics field coupling algorithm to compare and analyze the changes in leakage characteristics of each sealing component before and after hot melt curing and after high and low temperature cycling. Different leakage types are distinguished, the faulty sealing component and the specific leakage location are located, and the influence of working conditions on sealing performance is analyzed. Step 6: Determine the sealing performance based on multi-dimensional sealing performance qualification indicators, and provide targeted rectification plans for non-compliance cases.

Images