A piston assembly with a combined piston ring and unloading groove structure

Abstract

This utility model discloses a piston assembly with a combined piston ring and unloading groove structure, suitable for hydrogen combustion engines, including a piston ring assembly and a piston; the piston has a first ring groove and a second ring groove arranged sequentially from top to bottom, and an unloading groove is provided at the circumferential land between the first ring groove and the second ring groove, the lower end face of the unloading groove is inclined outward, and the inclination angle β satisfies 0°<β<90°; the piston ring assembly includes a top ring, which is disposed in the first ring groove, and the top ring includes a ring body and a scraper, the lower end face of the ring body is provided with a first groove that runs through the circumference, the first groove extends from the outer edge of the ring body inward, the first groove is used to embed the scraper, and the scraper can extend and retract radially along the first groove; the ring body and the scraper are respectively provided with a first opening and a second opening that run through both the radial and axial directions, and the circumferential offset angle α between the first opening and the second opening satisfies 90°≤α≤180°.

Description

Technical Field

[0001] This utility model relates to the field of hydrogen combustion engine technology, and in particular to a piston assembly with a combined piston ring and unloading groove structure. Background Technology

[0002] Hydrogen-fired engines, as core components of zero-carbon emission power systems, have become a research hotspot in the new energy field due to the significant advantages of hydrogen fuel's high energy density, fast combustion speed (approximately 8-10 times that of gasoline), and high thermal efficiency. They are widely used in high-end equipment such as new energy vehicles and heavy machinery. However, the unique operating characteristics of hydrogen-fired engines place far more stringent requirements on the sealing performance, structural stability, and anti-carbon deposit capabilities of piston and piston ring assemblies than on traditional internal combustion engines. As a key sealing component between the piston and cylinder liner, the piston ring assembly's core function is to prevent the mutual flow of high-pressure gas inside the cylinder and crankcase oil. The high burst pressure of 10-18 MPa inside the cylinder of a hydrogen-fired engine, the high-frequency pressure fluctuations of thousands of times per second, and the large amount of water vapor in the hydrogen combustion products make existing piston ring structures difficult to adapt.

[0003] In existing technologies, piston rings mostly adopt a single ring structure or a simple combination ring structure. Their design concepts largely follow the technical solutions of traditional fuel engines and are not optimized for the operating conditions of hydrogen engines. The fixed opening design of the traditional single-structure top ring makes it difficult to cope with the high-frequency pressure fluctuations of hydrogen engines. High-pressure gas can easily leak through the opening, and gas can easily accumulate under the top ring to form back pressure, pushing the top ring to float and creating gaps, further aggravating gas leakage and oil leakage, resulting in high engine oil consumption. The risk of carbon buildup and seizure is high. Water vapor produced by hydrogen combustion can easily condense under low load conditions (cylinder temperature 800~1200℃), and after mixing with carbon deposits produced by oil decomposition, it can easily accumulate in the piston ring opening and ring groove, causing piston ring seizure or wear of the sealing surface. The structural strength adaptability is poor. The hydrogen embrittlement effect of hydrogen engines amplifies the harm of structural stress concentration. The structural design of traditional top rings does not consider the optimization of stress distribution under high pressure, and the ring body is prone to cracking due to excessive local stress, affecting the service life of the engine. With the continuous upgrading of environmental regulations on engine emissions and the development of hydrogen-fired engines towards higher power and longer lifespan, the inadequacy of existing piston and piston ring structures has become increasingly prominent, severely restricting the industrialization and promotion of hydrogen-fired engines. Therefore, developing a piston and piston ring combination structure that can adapt to the operating conditions of hydrogen-fired engines and synergistically achieve functions such as enhanced sealing, prevention of top ring floating, and carbon deposit inhibition has become an urgent technical challenge to be solved in this field.

[0004] The above background information is provided only to aid in understanding the concept and technical solution of this utility model. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Utility Model Content

[0005] The purpose of this invention is to propose a piston assembly with a combined piston ring and unloading groove structure to solve the technical problems of insufficient piston ring sealing reliability, easy floating of the top ring and high risk of carbon buildup and jamming in the prior art.

[0006] Therefore, this utility model proposes a piston assembly with a combined piston ring and unloading groove structure.

[0007] Preferably, the present invention may also have the following technical features:

[0008] A piston assembly with a combined piston ring and unloading groove structure, suitable for a hydrogen fuel cell engine, includes a piston ring assembly and a piston;

[0009] The piston is provided with a first annular groove and a second annular groove from top to bottom. A ring unloading groove is provided at the annular bank between the first annular groove and the second annular groove. The lower end face of the unloading groove is inclined outward, and the inclination angle β satisfies 0°<β<90°.

[0010] The piston ring assembly includes a top ring disposed within the first ring groove. The top ring includes a ring body and a scraper. The lower end face of the ring body has a first groove that extends circumferentially. The first groove extends inward from the outer edge of the ring body and is used to embed the scraper. The scraper can extend and retract radially along the first groove. The ring body and the scraper are respectively provided with a first opening and a second opening that extend radially and axially. The circumferential offset angle α between the first opening and the second opening satisfies 90°≤α≤180°.

[0011] Preferably, the inclination angle β of the lower end face of the unloading groove satisfies: 30°≤β≤60°.

[0012] Preferably, the axial thickness d of the ring body and the axial height b of the first groove satisfy: d / b = 5~8.

[0013] Preferably, the radial length a, the axial height b of the first groove and the radial width c left on the inner side of the ring body satisfy: a / c=2.5~3.5, and a / b=5~8.

[0014] Preferably, the scraper blade and the first groove are in a transition fit with a clearance of 0.01~0.03mm.

[0015] Preferably, the piston is made of aluminum alloy or steel.

[0016] Preferably, the piston further includes a third annular groove, which is disposed below the second annular groove.

[0017] The beneficial effects of this utility model compared with the prior art include:

[0018] 1. This application adopts a combined top ring design of "ring body + scraper" with an opening staggered angle of 90°≤α≤180° to maximize the blocking of the high-pressure gas flow channel. At the same time, the inclined unloading groove at the ring bank can quickly release the accumulated gas pressure below the top ring and prevent the top ring from floating up and forming a sealing gap. With the combined effect of the two, the blow-by volume of the hydrogen fuel engine is reduced compared with the existing technology, which greatly improves the sealing reliability of the engine.

[0019] 2. The in-cylinder explosion pressure of the hydrogen-fired engine in this application is as high as 10~18MPa, and the pressure fluctuates frequently. The ring body needs to withstand the high pressure impact and the radial force of the scraper at the same time. The design of d / b=5~8 can ensure that the axial thickness d of the ring body is large enough to provide sufficient structural strength for the ring body and avoid axial deformation or breakage of the ring body under high pressure. At the same time, the axial height b of the first groove matches the axial thickness of the scraper, which can provide stable axial support for the scraper, prevent the scraper from moving around in high frequency vibration, ensure the fitting accuracy between the scraper and the ring body, and thus improve the sealing reliability.

[0020] 3. The ratio of a / c in this application of 2.5 to 3.5 can ensure that the radial length a of the scraper is large enough, thereby improving the scraping efficiency of the scraper for removing oil and the sealing effect for gas; at the same time, the reasonable reservation of c can avoid insufficient radial strength of the ring body due to excessive groove depth, and prevent the ring body from radially cracking under high pressure.

[0021] 4. Hydrogen embrittlement exacerbates the risk of cracking at stress concentration points in metallic materials. Matching the radial length 'a' and axial height 'b' of the scraper blade (a / b=5~8) ensures overall dimensional coordination of the scraper blade and avoids localized stress concentration caused by an imbalance in the a / b ratio (e.g., if a is too large and b is too small, stress cracks are prone to occur at the root of the scraper blade). Combined with an axial ratio of d / b=5~8, the scraper blade can obtain uniform support force in both the radial and axial directions, reducing stress concentration points, significantly improving the resistance of the scraper blade and ring to hydrogen embrittlement, and extending the service life of components under hydrogen combustion conditions. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the piston assembly according to a specific embodiment of the present invention.

[0023] Figure 2 This is a specific embodiment of the present utility model. Figure 1 Enlarged diagram of point B in the middle.

[0024] Figure 3 This is a top view of the top ring according to a specific embodiment of this utility model.

[0025] Figure 4 This is a cross-sectional view of the top ring according to a specific embodiment of this utility model.

[0026] Figure 5 This is a specific embodiment of the present utility model. Figure 4 Enlarged diagram of point A in the middle.

[0027] Explanation of reference numerals in the attached drawings: 1-top ring; 11-ring body; 111-first groove; 112-first opening; 12-scraper; 121-second opening; 2-piston; 21-first ring groove; 22-second ring groove; 23-unloading groove; 24-third ring groove. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to specific embodiments and the accompanying drawings. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope and application of the present invention.

[0029] Non-limiting and non-exclusive embodiments will be described with reference to the following figures, wherein the same reference numerals denote the same parts unless otherwise specifically stated.

[0030] A piston assembly with a combined piston ring and unloading groove structure, suitable for hydrogen fuel cell engines, is described below in conjunction with the appendix. Figures 1-5 The technical solution of this application will be further described in detail. The piston assembly includes a piston ring assembly and a piston 2.

[0031] The piston 2 is provided with a first ring groove 21 and a second ring groove 22 from top to bottom. A ring unloading groove 23 is provided at the circumferential land between the first ring groove 21 and the second ring groove 22. The lower end face of the unloading groove 23 is inclined outward, and the inclination angle β satisfies 0°<β<90°, which can guide the oil backflow and reduce carbon deposit accumulation.

[0032] The piston ring assembly includes a top ring 1 disposed within the first ring groove 21. The top ring 1 includes a ring body 11 and a scraper 12. The lower end face of the ring body 11 has a first groove 111 that extends circumferentially (not penetrating the top and inner surfaces of the ring body 11). The first groove 111 extends inward from the outer edge of the ring body 11 and is used to accommodate the scraper 12. The scraper 12 is radially extendable along the first groove 111. The size of the first groove 111 is related to the size of the scraper 12. Specifically, the scraper 12 and the first groove 111 are fitted with a transition fit, with a fit gap of 0.01~0.03mm. This ensures that there is no relative movement between the scraper 12 and the ring body 11 under high-frequency vibration conditions of the hydrogen fuel cell engine, while retaining a small gap for a small amount of condensate to flow back. The ring body 11 and the scraper 12 are respectively provided with a first opening 112 and a second opening 121 that penetrate radially and axially. The offset angle α between the first opening 112 and the second opening 121 satisfies 90°≤α≤180°. Through the synergistic design of "combined top ring 1 + inclined unloading groove 23", the gas pressure below the top ring 1 can be relieved, preventing the top ring 1 from floating up, while reducing the amount of gas and oil rising, which is suitable for the characteristics of the hydrogen fuel cell engine with fast combustion speed and large pressure fluctuation.

[0033] The aforementioned ring land is a protruding structure on the piston 2 body, located between the first ring groove 21 and the second ring groove 22, serving to separate the two piston rings and support their operation. It is understood that the ring body 11 and the scraper 12 are circumferential structures. In this application, "axial" refers to the direction of the piston 2's up-and-down movement, and "radial" refers to the radial direction pointing towards the center of the piston 2. The radial length a of the first groove 111 is the distance extending inward from the outer edge of the ring body 11. The axial thickness d of the ring body 11 is the dimension along the piston 2's movement direction. The radial width c left on the inner side of the ring body 11 is the distance from the inner side of the first groove 111 to the inner wall of the central hole of the ring body 11.

[0034] It should be noted that after the top ring 1 is assembled, the scraper 12 and the first groove 111 of the ring body 11 form an embedded fit. This structural design allows the scraper 12 to extend and retract only in the radial direction of the first groove 111 to adapt to the cylinder wall clearance. The circumferential fit between the scraper 12 and the first groove 111 has no relative displacement space. Therefore, the circumferential offset angle α between the first opening 112 of the ring body 11 and the second opening 121 of the scraper 12 almost remains at the assembly setting value and will not change with the reciprocating motion of the piston 2. Specifically, the appropriate model can be selected based on the vehicle's operating conditions to suit the usage needs of different hydrogen-powered vehicles. For example, for low-load vehicles primarily used for low-speed, short-distance travel (such as hydrogen-powered small urban commuter vehicles and short-distance delivery minivans), a top ring 1 with α=100°~110° can be selected. At this angle, the engine gas pressure is relatively low. This angle can both block direct gas leakage by staggering the openings and ensure the radial extension and retraction flexibility of the scraper 12, reducing structural rigidity redundancy and frictional power consumption. For medium-load vehicles that balance urban commuting and high-speed driving (such as hydrogen-powered compact family cars), the appropriate model can be selected. For SUVs, mid-size sedans, and intercity logistics light trucks, a top ring of α=120°~130° can be selected, balancing sealing performance and structural adaptability, stably withstanding medium gas pressure, and suitable for most common usage scenarios. For high-load vehicles with long-term heavy loads and high power output (such as hydrogen-powered heavy-duty freight trucks, engineering vehicles, and high-power commercial vehicles), a top ring of α=150°~160° can be selected. This extends the gas leakage path through a larger circumferential offset distance, improving sealing redundancy and effectively resisting the risk of gas leakage under high gas pressure. All angle selections are based on the structural characteristic that α remains constant after top ring assembly, and the angle range avoids interference at the opening edge, ensuring the proper functioning of the scraper extension and retraction function, and achieving precise matching of sealing performance for different vehicle types under different operating conditions.

[0035] In some examples of this embodiment, the inclination angle β of the lower end face of the unloading groove 23 satisfies: 30°≤β≤60°. Within this angle range, the pressure reduction effect of the unloading groove 23 can be guaranteed, while maximizing the oil return efficiency and further reducing the accumulation of carbon deposits on the inner wall of the unloading groove 23.

[0036] In other examples of this embodiment, the axial thickness d of the ring 11 and the height b of the first groove 111 satisfy the ratio d / b = 5~8. For example, the axial thickness d of the ring 11 is set to 25mm, and the axial height b of the first groove 111 (i.e., the axial thickness of the scraper 12) is set to 4mm, resulting in d / b = 6.25, which is within the ratio range of 5~8. This structure ensures that the scraper has sufficient axial support force while avoiding an increase in weight due to excessive axial thickness of the ring 11, thus meeting the lightweight requirements of hydrogen fuel cell engines. If d is too large, it will increase the weight of the piston ring assembly, affecting the engine's power response; if b is too large, it will weaken the effective support area of ​​the ring 11. The ratio d / b = 5~8, by precisely balancing the dimensions of d and b, minimizes the redundant weight of the ring 11 while ensuring strength and support, meeting the requirements of hydrogen fuel cell engines for lightweight components and helping to improve engine power density. The reasonable design of the axial thickness d of the ring body 11 can increase the contact area between the ring body 11 and the first ring groove 111, and improve the stability of the ring body 11 in the groove. Combined with the effect of the unloading groove 23 on the gas pressure below the top ring 1, it can effectively prevent the top ring 1 from floating due to the push of high pressure gas, reduce the sealing gap, reduce the amount of gas and oil rising, and meet the stringent requirements of hydrogen fuel cell engines for sealing performance.

[0037] In some further examples of this embodiment, the radial length a, axial height b of the first groove 111, and the radial width c reserved on the inner side of the ring 11 satisfy: a / c = 2.5~3.5, and a / b = 5~8. This proportional relationship adapts to the piston ring sizes of different engine models, ensuring both stable accommodation of the scraper 11 by the first groove 111 and ensuring the structural strength of the ring 11 through the reasonable reservation of the inner width c. Hydrogen combustion engines have a fast hydrogen combustion rate, requiring the scraper 12 to have a sufficient radial length a to ensure oil scraping and sealing area, while the inner radial width c of the ring 11 needs to be reserved sufficiently to maintain the strength of the ring 11. The ratio of the axial thickness d of the ring body 11 to the axial height b of the first groove 111 (d / b=5~8) ensures the axial strength of the ring body 11 and the axial support stability of the scraper 12. The ratio of the radial length a of the first groove 111 to the inner radial width c of the ring body 11 and the axial height b of the first groove 111 (a / c=2.5~3.5, a / b=5~8) ensures the radial sealing area of ​​the scraper 12 and the radial structural strength of the ring body 11. The two work together to reduce the pressure of the unloading groove 23, which enables the piston ring assembly to achieve reliable sealing under different operating conditions such as low load (idle speed) and high load (high speed climbing) of the hydrogen fuel cell engine. The blow-by volume and oil consumption rate are significantly reduced, which fully meets the operating condition adaptability requirements of the hydrogen fuel cell engine.

[0038] In other examples of this embodiment, such as Figure 1As shown, the piston 2 also includes a third annular groove 24, which is located below the second annular groove 22. The third annular groove 24 is used to install an oil ring, forming a combined sealing structure of "gas ring + oil ring" with the top ring 1 and the second ring. This structure is adapted to the stringent requirements of hydrogen combustion engines for oil consumption control, further reducing the risk of oil leaking into the combustion chamber. Specifically, the piston 2 is made of aluminum alloy or steel. Aluminum alloy is suitable for the lightweight requirements of hydrogen combustion engines, while steel is suitable for the high-pressure conditions of hydrogen combustion engines. High-strength steel can be used, which has excellent resistance to hydrogen embrittlement and high-temperature strength, and can withstand the in-cylinder high temperature of 1500~2000℃ and the explosion pressure of 10~18MPa in hydrogen combustion engines, extending the piston's service life.

[0039] Those skilled in the art will recognize that numerous variations are possible with respect to the above description, and the embodiments and figures are merely for describing one or more specific implementations.

[0040] Although exemplary embodiments of the present invention have been described and illustrated, those skilled in the art will understand that various changes and substitutions can be made thereto without departing from the spirit of the present invention. Furthermore, many modifications can be made to adapt specific situations to the doctrine of the present invention without departing from the central concept of the present invention described herein. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but may include all embodiments and equivalents that fall within the scope of the present invention.

Claims

1. A piston assembly having a combined piston ring and unloading groove structure, suitable for a hydrogen-fired engine, characterized in that, Includes piston ring assembly and piston; The piston is provided with a first annular groove and a second annular groove from top to bottom. A ring unloading groove is provided at the annular bank between the first annular groove and the second annular groove. The lower end face of the unloading groove is inclined outward, and the inclination angle β satisfies 0°<β<90°. The piston ring assembly includes a top ring disposed within the first ring groove. The top ring includes a ring body and a scraper. The lower end face of the ring body has a first groove that extends circumferentially. The first groove extends inward from the outer edge of the ring body and is used to embed the scraper. The scraper can extend and retract radially along the first groove. The ring body and the scraper are respectively provided with a first opening and a second opening that extend radially and axially. The circumferential offset angle α between the first opening and the second opening satisfies 90°≤α≤180°.

2. The piston assembly with a combined piston ring and unloading groove structure according to claim 1, characterized in that, The inclination angle β of the lower end face of the unloading groove satisfies: 30°≤β≤60°.

3. The piston assembly with a combined piston ring and unloading groove structure according to claim 1, characterized in that, The axial thickness d of the ring body and the axial height b of the first groove satisfy the following condition: d / b = 5~8.

4. The piston assembly with a combined piston ring and unloading groove structure according to claim 3, characterized in that, The radial length a, axial height b of the first groove and the radial width c left on the inner side of the ring body satisfy: a / c=2.5~3.5, and a / b=5~8.

5. The piston assembly with a combined piston ring and unloading groove structure according to claim 1, characterized in that, The scraper blade and the first groove are fitted with a transition fit, with a fit clearance of 0.01~0.03mm.

6. The piston assembly with a combined piston ring and unloading groove structure according to claim 1, characterized in that, The piston is made of aluminum alloy or steel.

7. The piston assembly with a combined piston ring and unloading groove structure according to claim 1, characterized in that, The piston also includes a third annular groove, which is located below the second annular groove.

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