Piston assembly and natural gas engine

Abstract

The invention relates to the technical field of natural gas engines, and particularly discloses a piston assembly and a natural gas engine. A cooling oil duct and an opening communicated with the cooling oil duct are formed in a piston head in the circumferential direction of the piston head, the piston head is fixedly connected to a piston skirt, and the piston skirt is provided with a hollow structure; the outer peripheral wall of the piston head and the outer peripheral wall of the piston skirt are arranged at intervals in the reciprocating sliding direction, and the cooling oil channel communicates with the hollowed-out structure through the opening. The external suspension type inner cooling oil duct structure is adopted, the interior of the piston head is hollowed out to form the cooling oil duct, the cooling oil duct is communicated with the external hollow structure, effective detection such as ultrasonic detection and flaw detection can be conveniently conducted on the surface of the cooling oil duct, the quality risk is accurately controlled, the quality of a piston assembly is guaranteed, and the stability and safety of engine operation are improved. Meanwhile, the lightweight hollow structure design is adopted, the friction area of the piston skirt is reduced, the friction power consumption of the piston assembly is effectively reduced, and the performance of an engine is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas engines, and particularly relates to a piston assembly and a natural gas engine. Background Art

[0002] The piston is the "heart" of an automotive engine, bearing alternating mechanical and thermal loads. It is one of the key components with the harshest working conditions in the engine, used to bear gas pressure and transmit it through the piston pin to the connecting rod to drive the crankshaft to rotate. In order to achieve forced heat dissipation under high-temperature and high-load working conditions and improve the performance and reliability of the engine, cooling oil channels are usually provided in the piston.

[0003] The existing piston structure usually forms the cooling oil channels by integral casting. Since the cooling oil channels are relatively small in volume compared to the piston and are annularly enclosed in the piston head, it is difficult to precisely control the surface quality of the internal cooling oil channels of the piston. The internally cast cooling oil channels are difficult to clean, the surface defects are difficult to control, and flaw detection inspections are required. The production process is cumbersome, the detection is difficult and complex, and it completely relies on the casting process. Once undetected, major quality accidents such as cylinder scoring and cylinder inversion will occur in the engine, which will affect the performance and reliability of the engine to a certain extent.

[0004] Therefore, there is an urgent need for a piston assembly and a natural gas engine to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a piston assembly and a natural gas engine to solve the problem that the surface quality of the cooling oil channels of the existing piston structure is difficult to control, which affects the performance and reliability of the engine to a certain extent.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] On the one hand, the present invention provides a piston assembly that can reciprocally slide in the cylinder of a natural gas engine. The piston assembly includes:

[0008] A piston head, in which a cooling oil channel is provided along its circumferential direction, and an opening communicating with the cooling oil channel;

[0009] A piston skirt, the piston head is fixedly connected to the piston skirt, and the piston skirt is provided with a hollow structure so that the outer peripheral wall of the piston head and the outer peripheral wall of the piston skirt are spaced apart along the reciprocating sliding direction. The cooling oil channel communicates with the hollow structure through the opening.

[0010] As a preferred technical solution of the above piston assembly, the piston assembly further includes a plugging assembly, and the plugging assembly is installed in the opening and can close the opening.

[0011] As a preferred technical solution of the above piston assembly, the blocking assembly includes a first sheet body and a second sheet body. A clamping groove structure is formed on the inner side wall of the cooling oil passage. The clamping groove structure includes a first clamping groove and a second clamping groove. The first sheet body is embedded in the first clamping groove and blocks part of the opening, and the second sheet body is embedded in the second clamping groove and blocks the remaining part of the opening.

[0012] As a preferred technical solution of the above piston assembly, both the first sheet body and the second sheet body are semi-circular.

[0013] As a preferred technical solution of the above piston assembly, both the first sheet body and the second sheet body are elastic steel sheets.

[0014] As a preferred technical solution of the above piston assembly, the surface of the cooling oil passage is formed by full mechanical processing.

[0015] As a preferred technical solution of the above piston assembly, both the piston head and the piston skirt are made of ductile iron material.

[0016] As a preferred technical solution of the above piston assembly, the piston head and the piston skirt are integrally formed.

[0017] As a preferred technical solution of the above piston assembly, a plurality of annular grooves are formed on the outer peripheral wall of the piston head along the reciprocating sliding direction, and adjacent two of the annular grooves are arranged at intervals.

[0018] On the other hand, the present invention further provides a natural gas engine, including at least one cylinder. The cylinder includes a cylinder liner and the piston assembly described in any one of the above solutions arranged in the cylinder liner.

[0019] The beneficial effects of the present invention are:

[0020] The present invention provides a piston assembly and a natural gas engine. The piston assembly is reciprocally slidably disposed in a cylinder of the natural gas engine. The piston assembly includes a piston head and a piston skirt. A cooling oil passage is formed along the circumferential direction of the piston head, and an opening communicating with the cooling oil passage is provided. The piston head is fixedly connected to the piston skirt. The piston skirt is provided with a hollow structure, so that the outer peripheral wall of the piston head and the outer peripheral wall of the piston skirt are spaced apart along the reciprocating sliding direction. The cooling oil passage communicates with the hollow structure through the opening. With such a setting, an externally suspended internal cooling oil passage structure is adopted, the inside of the piston head is hollowed out to form the cooling oil passage, and the cooling oil passage conducts the external hollow structure. The production process is simple, which is convenient for cleaning the surface of the cooling oil passage and performing effective inspections such as ultrasonic inspection and flaw detection, so as to accurately control the quality risk, ensure the quality of the piston assembly, and improve the operation stability and safety of the engine. At the same time, the lightweight hollow structure design is adopted, which reduces the frictional contact area of the piston skirt, can effectively reduce the frictional power consumption of the piston assembly, and improve the performance and reliability of the engine. Description of the Drawings

[0021] Figure 1 is a cross-section of the piston assembly provided by the present invention Figure 1 ;

[0022] Figure 2 is Figure 1 a partial enlarged view of part A in

[0023] Figure 3 is a schematic structural view of the piston assembly provided by the present invention;

[0024] Figure 4 is a cross-section of the piston assembly provided by the present invention Figure 2 .

[0025] Wherein:

[0026] 1. Piston head; 101. Cooling oil passage;

[0027] 2. Piston skirt; 201. Hollow structure;

[0028] 3. First sheet; 4. Second sheet; 5. Card slot structure; 6. Annular groove. Detailed Embodiments

[0029] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, in which the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions from beginning to end. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0030] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0031] Unless otherwise clearly specified and defined, the terms "installed", "connected", "connected to", "fixed" shall be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] Unless otherwise clearly specified and defined, the first feature being "above" or "below" the second feature may include the first feature and the second feature being in direct contact, or may include the first feature and the second feature not being in direct contact but being in contact through other features therebetween. Moreover, the first feature being "above", "over" and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "under" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0033] The technical solution of the present invention will be further described below with reference to the drawings and through specific embodiments.

[0034] Such as Figures 1 to 4As shown in the figure, this embodiment provides a piston assembly that can reciprocally slide within the cylinder of a natural gas engine. The piston assembly includes: a piston head 1 and a piston skirt 2. A cooling oil passage 101 is circumferentially formed inside the piston head 1 along its own circumference, and an opening communicating with the cooling oil passage 101 is provided. The piston head 1 is fixedly connected to the piston skirt 2. The piston skirt 2 is provided with a hollow structure 201, so that the outer peripheral wall of the piston head 1 and the outer peripheral wall of the piston skirt 2 are spaced apart along the reciprocating sliding direction. The cooling oil passage 101 communicates with the hollow structure 201 through the opening. With such a setting, an external suspended internal cooling oil passage structure is adopted. The inside of the piston head 1 is hollowed out to form the cooling oil passage 101, and the cooling oil passage 101 leads to the external hollow structure 201. The production process is simple, which is convenient for cleaning the surface of the cooling oil passage 101 and performing effective defect detections such as ultrasonic testing and flaw detection, so as to accurately control the quality risk, ensure the quality of the piston assembly, and improve the operation stability and safety of the engine. At the same time, with the design of the lightweight hollow structure 201, the frictional contact area of the piston skirt 2 is reduced, which can effectively reduce the frictional power consumption of the piston assembly and improve the performance and reliability of the engine.

[0035] Optionally, in order to improve the oscillating cooling effect of the piston assembly, the piston assembly further includes a plugging component, which is installed in the opening and can close the opening. With such a setting, the plugging component is installed in the opening to form a closed cooling oil passage 101, so that the cooling engine oil reciprocally flows in the cooling oil passage 101 to achieve high-frequency oscillation (synchronized with the movement of the piston assembly). This design not only improves the cooling efficiency but also enhances the heat dissipation performance, further strengthens the heat exchange process, and realizes dynamic cooling. In addition, by optimizing the structure and size of the cooling oil passage 101, the flow rate and pressure of the cooling engine oil can be better controlled.

[0036] Specifically, this embodiment exemplarily provides the following technical solution: The plugging component includes a first sheet body 3 and a second sheet body 4. A card slot structure 5 is formed on the inner side wall of the cooling oil passage 101. The card slot structure 5 includes a first card slot and a second card slot. The first sheet body 3 and the second sheet body 4 are symmetrically arranged. The first sheet body 3 is embedded in the first card slot and blocks part of the opening, and the second sheet body 4 is embedded in the second card slot and blocks the remaining part of the opening. With such a setting, the first sheet body 3 and the second sheet body 4 are symmetrically embedded in the card slot structure 5 to ensure balanced symmetrical loads, so that the pressure, thermal expansion force, etc. borne by the cooling oil passage 101 are evenly transmitted in two directions, avoiding local stress concentration caused by unilateral stress, and effectively extending its fatigue life.

[0037] Furthermore, the first sheet body 3 and the second sheet body 4 can be respectively integrated with a first micro pressure sensor and a second micro pressure sensor to monitor the pressure in the cooling oil passage 101 in real time. It should be noted that the above-mentioned micro pressure sensor has high sensitivity and fast response characteristics, and can accurately capture the subtle pressure changes inside the cooling oil passage 101. Through continuous monitoring, the system can promptly detect any abnormal pressure fluctuations to ensure the safety and stability of the equipment operation. If the seal fails, the micro pressure sensor will immediately detect the abnormal pressure and trigger an alarm through a preset alarm mechanism to remind the operator to take corresponding measures to prevent potential failures from occurring.

[0038] Of course, in other embodiments, the blocking component can also adopt a connection structure in which a high-temperature resistant permanent magnet (such as samarium cobalt alloy) is in contact with a metal sealing surface and is fixed by magnetic adsorption to maintain high-pressure sealing, which is more convenient for quick disassembly and maintenance; alternatively, the blocking component can also adopt a shape memory alloy plug (such as NiTi alloy). This material has unique thermal response characteristics and can return to a pre-set shape within a specific temperature range, so as to provide a reliable sealing effect in a high-temperature environment. When in use, it can automatically expand at high temperatures to enhance the sealing pressure, and is convenient for disassembly and maintenance at low temperatures. No further limitation is made here.

[0039] Optionally, the structures of the first sheet body 3 and the second sheet body 4 are completely the same, and both are semi-circular.

[0040] Optionally, both the first sheet body 3 and the second sheet body 4 are elastic steel sheets. With this setting, the high strength of the spring steel sheet can withstand the high explosion pressure and detonation conditions in the engine combustion chamber, avoiding deformation or rupture under extreme pressure. It does not require a weld design, and only the slot structure 5 and the interference fit are used to achieve sealing, eliminating the weakening of the heat-affected zone caused by the welding process and reducing the risk of weld cracking at high temperatures. It is convenient and reliable to install, and the inner wall of the spring steel sheet is smooth, which can effectively reduce the oil flow resistance, enhance the reciprocating oscillation effect of the oil in the cooling oil passage 101, and improve the heat exchange efficiency.

[0041] In this embodiment, in order to improve the thermal management efficiency and extend the service life of the piston assembly, the inner wall structure of the cooling oil passage 101 is topologically optimized. Specifically, spiral or wavy flow guiding grooves are machined on the inner wall of the cooling oil passage 101 to enhance the oil turbulence, break the boundary layer heat insulation effect, and improve the heat transfer coefficient. At the same time, a micro-perturbation flow structure is designed, that is, micro-pits or fins (similar to the surface of a golf ball) are arranged on the inner wall of the cooling oil passage 101 to strengthen the local heat dissipation through the eddy current effect and avoid a significant increase in the flow resistance. In addition, an asymmetric flow passage cross-section can be designed, that is, according to the heat distribution range of the piston assembly (such as a denser high-temperature area at the top), a variable cross-section oil passage is designed to adaptively match the heat load gradient and significantly improve the heat exchange and cooling efficiency. This optimization not only improves the heat transfer performance of the cooling oil passage but also effectively reduces the heat accumulation, thereby extending the service life of the piston assembly.

[0042] Optionally, advanced surface treatment and coating technologies can also be used on the inner wall of the cooling oil passage 101 to optimize the performance. High thermal conductivity nanomaterials, such as graphene-doped ceramic coatings, can be sprayed on the inner wall of the cooling oil passage 101 to reduce the contact thermal resistance between the cooling oil and the metal, improve the fluidity of the cooling oil flow, further enhance the high-temperature resistance and corrosion resistance of the cooling oil passage 101, and ensure efficient thermal management under extreme working conditions. The wettability of the inner wall of the cooling oil passage 101 can be regulated by chemical etching or laser treatment to achieve oil-repellent / oil-loving modification. The oil-loving surface promotes the spreading of the oil film, and the oil-repellent area accelerates the flow and renewal of the oil. At the same time, a self-cleaning design is completed, and an anti-carbon deposition coating, such as diamond-like carbon film, is used on the inner wall of the cooling oil passage 101 to prevent the cooling oil from coking and blocking the cooling oil passage 101 at high temperatures. It should be noted that the diamond-like carbon film has extremely high hardness and low friction coefficient, which can effectively prevent carbon deposition formation, thereby extending the service life of the equipment and improving the operation efficiency.

[0043] Optionally, the surface of the cooling oil passage 101 is manufactured by full mechanical processing. With this setting, machining the cooling oil passage 101 by full mechanical processing effectively ensures the surface quality inside the cooling oil passage 101, can avoid the difficulties of sand cleaning in the cooling oil passage 101 and the inspection of inner surface defects of the cooling oil passage 101, and guarantees the qualified rate of the finished piston assembly. It should be noted that the cooling oil passage 101 is machined and formed from the outside of the piston skirt 2.

[0044] Furthermore, the surface of the cooling oil channel 101 is mirror-polished, and the roughness of the inner wall can be reduced by fluid polishing or electrolytic polishing, which reduces the resistance when the oil flows and greatly increases the flow rate. It should be noted that fluid polishing uses a high-speed flowing abrasive liquid to finely grind the surface, while electrolytic polishing removes tiny protrusions on the metal surface through electrochemical reactions to make the surface smoother. Furthermore, a heat dissipation rib structure can be embedded, that is, high thermal conductivity materials such as copper alloy fins are pre-embedded during the processing stage. Copper alloys are often used to manufacture efficient heat dissipation devices due to their excellent thermal conductivity and corrosion resistance, which can quickly conduct heat. This design not only improves the cooling efficiency, but also extends the performance and service life of the equipment.

[0045] In this embodiment, a sensor can be embedded in the inner wall of the cooling oil channel 101 to realize intelligent thermal management integration, that is, an optical fiber temperature sensor is integrated at a key position of the cooling oil channel 101 to monitor the cooling efficiency in real time. The optical fiber temperature sensor adopts advanced optical sensing technology, which can accurately measure the temperature changes in the cooling oil channel 101 to ensure the high accuracy and reliability of the data. And further, by timely feeding back the data of the optical fiber temperature sensor to the electronic control unit (ECU), the system can quickly analyze and adjust the flow of the cooling oil pump, thereby optimizing the cooling effect and improving the overall performance and durability of the engine. In addition, this intelligent thermal management system also has a self-diagnosis function, which can automatically issue an alarm when an abnormal situation occurs, further ensuring the safe operation of the equipment. At the same time, piezoelectric ceramic sheets are integrated on the inner wall of the cooling oil channel 101 to regularly generate high-frequency vibrations to peel off deposits to achieve active vibration descaling.

[0046] Optionally, in order to improve the anti-knock performance of the piston assembly and further reduce the production cost of the engine, the piston head 1 and the piston skirt 2 are both made of ductile iron. It should be noted that the heat resistance of ductile iron material itself is close to that of forged steel, which can effectively prevent the piston assembly from melting. At the same time, the cast iron manufacturing process will greatly reduce the cost, and the maximum explosion pressure of the natural gas engine is lower than that of the diesel engine. The ductile iron material can well meet its strength requirements. From then on, the dual requirements of reliability and cost of the natural gas engine are balanced through structural design and combined process, avoiding the quality risks of traditional structural cast iron pistons, so as to facilitate batch and large-scale production.

[0047] Optionally, the piston head 1 and the piston skirt 2 can be integrally formed. With this arrangement, the integrally formed piston head 1 and piston skirt 2 not only have better structural stability, but also can significantly reduce the number of additional components, effectively improving the production and processing efficiency. In addition, this design enables the piston assembly to have higher durability and reliability in high-temperature and high-pressure environments, while reducing the complexity and potential assembly errors during the assembly process. The integral forming process can also optimize the material distribution, improve the material utilization rate, and further reduce costs.

[0048] Optionally, a plurality of annular grooves 6 are formed in the outer peripheral wall of the piston head 1 along the reciprocating sliding direction, and any two adjacent annular grooves 6 are spaced and evenly arranged. With this arrangement, the plurality of annular grooves 6 are all used for installing piston rings, and the piston rings are made of wear-resistant materials and have excellent elasticity and sealing performance, which can ensure the airtightness of the cylinder, prevent the leakage of high-temperature and high-pressure gases in the combustion chamber, and effectively reduce the friction loss. In addition, the heat at the top of the piston assembly can be quickly transferred to the cylinder wall by conduction, preventing local overheating, thereby improving the overall efficiency and reliability of the engine.

[0049] This embodiment also provides a natural gas engine, including at least one cylinder, the cylinder including a cylinder liner and the piston assembly in the above solution disposed in the cylinder liner.

[0050] Obviously, the above embodiments of the present invention are merely examples for clearly explaining the present invention, and are not intended to limit the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A piston assembly that is reciprocally slidably disposed within a cylinder of a natural gas engine, characterized in that, The piston assembly includes: A piston head (1), in which a cooling oil passage (101) is formed along its circumferential direction, and an opening communicating with the cooling oil passage (101); A piston skirt (2), the piston head (1) is fixedly connected to the piston skirt (2), and the piston skirt (2) is provided with a hollow structure (201) so that the outer peripheral walls of the piston head (1) and the piston skirt (2) are spaced apart along the reciprocating sliding direction, and the cooling oil passage (101) communicates with the hollow structure (201) through the opening; 2. The piston assembly according to claim 1, characterized in that, The piston assembly further includes a plugging component, which is installed in the opening and can close the opening; 3. The piston assembly according to claim 2, characterized in that, The plugging component includes a first sheet body (3) and a second sheet body (4), a clamping groove structure (5) is formed on the inner side wall of the cooling oil passage (101), the clamping groove structure (5) includes a first clamping groove and a second clamping groove, the first sheet body (3) is embedded in the first clamping groove and plugs part of the opening, and the second sheet body (4) is embedded in the second clamping groove and plugs the remaining part of the opening; 4. The piston assembly according to claim 3, characterized in that, Both the first sheet body (3) and the second sheet body (4) are semi-circular; 5. The piston assembly according to claim 3, characterized in that, Both the first sheet body (3) and the second sheet body (4) are elastic steel sheets; 6. The piston assembly according to any one of claims 1-5, characterized in that, The surface of the cooling oil passage (101) is formed by full mechanical processing; 7. The piston assembly according to any one of claims 1-5, characterized in that, Both the piston head (1) and the piston skirt (2) are made of ductile iron material; 8. The piston assembly according to any one of claims 1-5, characterized in that, The piston head (1) and the piston skirt (2) are integrally formed; 9. The piston assembly according to any one of claims 1-5, characterized in that, A plurality of annular grooves (6) are formed on the outer peripheral wall of the piston head (1) along the reciprocating sliding direction, and adjacent two annular grooves (6) are spaced apart; 10. A natural gas engine, characterized in that, It includes at least one cylinder, and the cylinder includes a cylinder liner and the piston assembly according to any one of claims 1-9 provided in the cylinder liner.

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