Piston, piston assembly, diesel engine and vehicle

Abstract

The invention relates to a piston, a piston assembly, a diesel engine and a vehicle. The piston comprises a head part and a skirt part. A first annular groove and a second annular groove which are sequentially arranged in the reciprocating sliding direction are formed in the outer wall of the head part, the first annular groove is arranged in the circumferential direction of the head part and used for installing a first piston ring, and the second annular groove is arranged in the circumferential direction of the head part and used for installing a second piston ring. A third annular groove is formed in the outer wall of the skirt part, and the third annular groove is arranged in the circumferential direction of the skirt part and used for installing a third piston ring. Compared with the mode that the three annular grooves are all formed in the outer wall of the head in the prior art, the third annular groove is specifically an oil annular groove, is close to the oil pan and is far away from the head, so that the temperature of the third annular groove is lower than that of the annular groove of the head, and the conditions of engine oil coking, carbon deposition and the like in the third annular groove can be greatly avoided; therefore, the abrasion loss of the piston ring is reduced, and the service lives of the piston ring and the piston assembly are greatly prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of diesel engine parts, and in particular to a piston, a piston assembly, a diesel engine and a vehicle. Background Art

[0002] The piston is the "heart" of the engine, bearing alternating mechanical and thermal loads. It is one of the key components in the engine with the worst working conditions. It is used to withstand gas pressure and transmit it to the connecting rod through the piston pin to drive the crankshaft to rotate. The piston ring is a metal ring embedded in the mounting groove of the piston. It has four functions in the internal combustion engine, namely sealing high-pressure gas, scraping off excess oil, supporting piston movement and exporting heat. For commercial diesel engines, my country has now fully implemented the National VI emission standards. In addition to the control of pollutant exhaust emissions, requirements such as improving combustion efficiency, extending B10 life, extending oil change cycles, reducing weight, reducing friction power consumption, reducing fuel consumption, and reducing carbon dioxide emissions are constantly increasing. However, after long-term use, the piston ring is prone to wear defects, which greatly weakens the various functions in the internal combustion engine. It needs to be replaced and maintained regularly, and its service life is short. Summary of the invention

[0003] Based on this, it is necessary to overcome the defects of the prior art and provide a piston, a piston assembly, a diesel engine and a vehicle, which can reduce the amount of wear and increase the service life.

[0004] A piston is used to be reciprocatingly slidably arranged in a cylinder sleeve of an internal combustion engine cylinder, and the piston comprises:

[0005] A head, wherein a first annular groove and a second annular groove are sequentially arranged along the reciprocating sliding direction on the outer wall of the head, wherein the first annular groove is arranged around the circumference of the head and is used to install a first piston ring, and the second annular groove is arranged around the circumference of the head and is used to install a second piston ring; and

[0006] A skirt portion is connected to the head portion, a third annular groove is formed on the outer wall of the skirt portion, the third annular groove is arranged around the circumference of the skirt portion and is used to install a third piston ring.

[0007] In one embodiment, a fourth annular groove is further formed on the outer wall of the head, the fourth annular groove is arranged circumferentially around the head and is used to install a fourth piston ring, and the first annular groove, the second annular groove, the fourth annular groove and the third annular groove are arranged in sequence along the reciprocating sliding direction.

[0008] A piston assembly comprises the piston, and also comprises a cylinder liner, a first piston ring, a second piston ring and a third piston ring. The piston is reciprocatingly slidably arranged in the cylinder liner, the first piston ring is arranged in the first annular groove, the second piston ring is arranged in the second annular groove, and the third piston ring is arranged in the third annular groove. The first piston ring, the second piston ring and the third piston ring are all used for abutting and cooperating with the inner wall of the cylinder liner and can slide relative to each other with the reciprocating motion of the piston.

[0009] In one embodiment, the piston assembly also includes a fourth piston ring, and a fourth annular groove is formed on the outer wall of the head. The fourth annular groove is arranged circumferentially around the head and is used to install the fourth piston ring. The first annular groove, the second annular groove, the fourth annular groove and the third annular groove are arranged in sequence along the reciprocating sliding direction.

[0010] In one embodiment, the third piston ring includes a three-piece combined oil ring structure, a spiral spring type oil ring structure or a nose type ring structure.

[0011] In one embodiment, when the third piston ring is set as a three-piece combined oil ring structure, the third piston ring includes an annular elastic seat and two elastic sheets arranged in an annular shape; the elastic seat abuts against the bottom wall of the third annular groove, and a partial structure of the elastic seat extends to the outside of the third annular groove and abuts and cooperates with the inner wall of the cylinder liner; the two elastic sheets are respectively connected to the two opposite end surfaces of the elastic seat along the reciprocating motion direction, and each of the elastic sheets extends to the outside of the third annular groove and abuts and cooperates with the inner wall of the cylinder liner; and the length of the portion of each elastic sheet extending to the outside of the third annular groove is greater than the length of the portion of the elastic seat extending to the outside of the third annular groove.

[0012] In one embodiment, the elastic seat includes a main body ring and an elastic abutment portion connected to the main body ring; the main body ring is provided with mounting portions at two opposite ends along the reciprocating motion direction, and each elastic sheet is correspondingly mounted on each mounting portion; the elastic abutment portion includes a spring sheet that is reciprocatingly bent along the radial direction of the third piston ring.

[0013] In one embodiment, the radial cross section of the first piston ring is set as a trapezoidal barrel surface; the side of the second piston ring facing the cylinder liner is set as an anti-distorted cone surface, and the fourth piston ring includes a nose portion facing the inner wall of the cylinder liner, and the side of the nose portion facing the cylinder liner is provided with a positive twisted cone surface;

[0014] Alternatively, the side surface of the second piston ring facing the cylinder liner and the side surface of the fourth piston ring facing the cylinder liner are both configured as anti-twisted conical surfaces;

[0015] Alternatively, the second piston ring includes a nose-shaped portion disposed facing the inner wall of the cylinder liner, and the fourth piston ring includes a nose-shaped portion disposed facing the inner wall of the cylinder liner.

[0016] A diesel engine comprises the piston assembly.

[0017] A vehicle comprises the diesel engine.

[0018] The above-mentioned piston, piston assembly, diesel engine and vehicle have the first annular groove and the second annular groove arranged on the head, and the third annular groove arranged on the skirt. Compared with the method of forming the three annular grooves on the outer wall of the head in the related art, the third annular groove is specifically an oil ring groove, which is close to the oil pan and relatively farther away from the head, that is, farther away from the high temperature area of ​​the head. In this way, the temperature of the third annular groove is lower than the temperature of the annular groove of the head, thereby greatly avoiding the occurrence of oil coking and carbon deposition inside the third annular groove, thereby reducing the wear of the piston ring and greatly extending the service life of the piston ring and the piston assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 is a radial cross-sectional structural diagram of a piston assembly according to an embodiment of the present application.

[0020] FIG. 2 is an enlarged structural diagram of the structure shown in FIG. 1 at position A. FIG.

[0021] FIG. 3 is an enlarged structural diagram of the structure shown in FIG. 1 at position B. FIG.

[0022] 10. Piston assembly; 11. Piston; 111. Head; 1111. First annular groove; 1112. Second annular groove; 1113. Third annular groove; 1114. Fourth annular groove; 112. Skirt; 12. Cylinder liner; 13. First piston ring; 14. Second piston ring; 15. Third piston ring; 151. Elastic seat; 1511. Main body ring; 1512. Elastic abutment; 152. Elastic sheet; 16. Fourth piston ring. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0024] It should be noted that the piston is a reciprocating part in the engine cylinder. The basic structure of the piston includes a head and a skirt that are connected to each other along the extending reciprocating direction. The head of the piston is the main part of the combustion chamber, and its shape is related to the selected combustion chamber form. Gasoline engines mostly use flat-top pistons, which have the advantage of a small heat absorption area. The side of the diesel engine's piston head facing the combustion chamber has various pits, and their specific shape, position and size must be adapted to the requirements of the diesel engine's mixture formation and combustion.

[0025] As described in the background technology, the piston rings in the prior art are prone to wear after long-term use. The inventors have found that the reason for this problem is that there are usually three piston ring grooves on the piston of an internal combustion engine, including two air ring grooves and one oil ring groove. The three piston ring grooves are usually arranged on the head of the piston. However, the head of the piston is located in a high-temperature area. The oil in the oil ring groove is prone to coking and carbon deposition under high temperature, which increases the wear of the piston ring, thereby weakening the various functions of the piston ring in the internal combustion engine and reducing the service life of the piston ring.

[0026] Based on the above reasons, the present application provides a technical solution for a piston, a piston assembly and a diesel engine, which can reduce wear and increase service life.

[0027] Referring to FIG. 1 , FIG. 1 shows a radial cross-sectional structural diagram of a piston assembly 10 according to an embodiment of the present application. FIG. 2 and FIG. 3 show enlarged structural diagrams of the structure shown in FIG. 1 at A and B, respectively. A piston assembly 10 provided in an embodiment of the present application includes a piston 11, a cylinder sleeve 12, a first piston ring 13, a second piston ring 14, and a third piston ring 15. The piston 11 is reciprocatingly slidably arranged in the cylinder sleeve 12. Specifically, the piston 11 includes a head 111 and a skirt 112. A first annular groove 1111 and a second annular groove 1112 are formed on the outer wall of the head 111 and are arranged in sequence along the reciprocating sliding direction. The first annular groove 1111 is arranged circumferentially around the head 111 and is used to install the first piston ring 13, and the second annular groove 1112 is arranged circumferentially around the head 111 and is used to install the second piston ring 14. The skirt 112 is connected to the head 111, and a third annular groove 1113 is formed on the outer wall of the skirt 112. The third annular groove 1113 is arranged around the circumference of the skirt 112 and is used to install the third piston ring 15. The first piston ring 13 is arranged in the first annular groove 1111, the second piston ring 14 is arranged in the second annular groove 1112, and the third piston ring 15 is arranged in the third annular groove 1113. The first piston ring 13, the second piston ring 14 and the third piston ring 15 are all in abutment with the inner wall of the cylinder sleeve 12 and can slide with each other as the piston 11 reciprocates.

[0028] The above-mentioned piston assembly 10 and piston 11 have a first annular groove 1111 and a second annular groove 1112 arranged on the head 111, and a third annular groove 1113 arranged on the skirt 112. Compared with the method of forming three annular grooves on the outer wall of the head 111 in the related art, the third annular groove 1113 in this embodiment is specifically an oil ring groove, and is close to the oil pan, and is relatively farther away from the head 111, that is, farther away from the high temperature area of ​​the head 111. In this way, the temperature of the third annular groove 1113 is lower than the temperature of the annular groove of the head 111, thereby greatly avoiding the occurrence of oil coking and carbon deposition in the third annular groove 1113, thereby reducing the wear of the piston 11 ring, and greatly extending the service life of the piston 11 ring and the piston assembly 10.

[0029] In addition, during use of the piston 11 in this embodiment, by measuring the temperature of the third annular groove 1113, it can be found that the temperature of the third annular groove 1113 is between 120°C and 150°C, which is much lower than the temperature at the head 111, which can greatly avoid the occurrence of oil coking and carbon deposition in the third annular groove 1113.

[0030] In the related art, in order to meet the necessary temperature required for the regeneration of the after-treatment system, the diesel engine introduces a thermal management control system with a throttle action. The specific principle is to use the throttle action to control the intake volume of the diesel engine, and to adjust the injection volume to achieve the increase of the diesel engine exhaust temperature. Although the thermal management control system can provide the required high temperature conditions for the after-treatment system, at the same time, with the action of the throttle, the pressure of the intake pipeline is reduced, especially in the low-speed stage of the commercial vehicle diesel engine. The engine speed itself is low and the intake pressure is small. In addition, the throttle action causes the intake pressure to be much lower than the atmospheric pressure. Sometimes the intake negative pressure is ≤70Kpa, or even ≤60Kpa. The low intake negative pressure can easily lead to the sealing failure of the piston assembly 10 of the commercial vehicle diesel engine, especially in the intake stroke of the diesel engine. Under the action of the intake negative pressure, the lubricating oil on the piston 11 and the cylinder liner 12 is "sucked" into the combustion chamber by the negative pressure in the cylinder, or burned, or discharged into the exhaust pipeline, resulting in a large consumption of diesel engine oil. In addition, commercial vehicles have some special application scenarios: port vehicles, short-distance vehicles in fixed areas, and vehicles used in cities. These scenarios also have the defects of low intake pressure and high oil consumption because most of the operating time is in idling conditions.

[0031] Based on this, in one embodiment, a fourth annular groove 1114 is further formed on the outer wall of the head 111. The fourth annular groove 1114 is arranged around the circumference of the head 111 and is used to install the fourth piston ring 16. Specifically, the first annular groove 1111, the second annular groove 1112, the fourth annular groove 1114 and the third annular groove 1113 are arranged in sequence along the reciprocating sliding direction of the piston 11. In this way, the number of annular grooves on the outer wall of the piston 11 is four, which is one more than the three annular grooves in the related art. At the same time, the number of piston 11 rings is increased by one, so that the number of labyrinth structures formed by the piston 11 rings and the annular grooves is increased accordingly. The increased labyrinth structure can greatly extend the path length of the oil being sucked into the combustion chamber, which can not only prevent the gas in the combustion chamber from entering the cylinder liner 12, but also reduce the oil leakage, that is, it can greatly reduce the oil consumption of the diesel engine under the negative pressure of the intake air, making it possible to cancel the exhaust throttle valve in the thermal management system of the diesel engine, thereby greatly reducing the cost of the whole machine. In addition, the overall structure is simple in layout, and has no substantial processing and assembly differences from conventional pistons 11 and piston 11 rings.

[0032] In one embodiment, the piston assembly 10 further includes a fourth piston ring 16. A fourth annular groove 1114 is further formed on the outer wall of the head 111. The fourth annular groove 1114 is arranged circumferentially around the head 111 and is used to install the fourth piston ring 16. The first annular groove 1111, the second annular groove 1112, the fourth annular groove 1114 and the third annular groove 1113 are arranged in sequence along the reciprocating sliding direction. In this way, the first piston ring 13, the second piston ring 14, the fourth piston ring 16 and the third piston ring 15 can each play a role in sealing the gas, preventing the gas inside the combustion chamber from entering the cylinder liner 12 through the gap between the piston 11 and the inner wall of the cylinder liner 12, thereby preventing the combustion gas from leaking into the crankcase; wherein, since the first piston ring 13 is relatively closer to the combustion chamber, the first piston ring 13 is used to isolate most of the gas from entering the cylinder liner 12, and the second piston ring 14, the third piston ring 15 and the fourth piston ring 16 cooperate with each other to play an auxiliary sealing role, blocking the remaining gas, thereby effectively preventing the gas from entering the cylinder liner 12, thereby preventing the combustion gas from leaking into the crankcase.

[0033] In addition, the first piston ring 13, the second piston ring 14, the fourth piston ring 16 and the third piston ring 15 can each play a role in controlling the distribution of the engine oil, and can scrape off the excess lubricating oil on the inner wall of the cylinder liner 12 when the piston 11 moves downward, and spread a uniform oil film on the inner wall of the cylinder liner 12 when the piston 11 moves upward, so as to prevent the lubricating oil from entering the combustion chamber and burning, and reduce the friction resistance between the piston 11 and the inner wall of the cylinder liner 12. Among them, since the third piston ring 15 is relatively closer to the oil pan, the third piston ring 15 is mainly used to scrape off the excess engine oil on the inner wall of the cylinder liner 12, prevent the engine oil from entering the cylinder liner 12 and burning, and reduce the wear of the piston 11 and the piston 11 ring and the cylinder wall. The first piston ring 13, the second piston ring 14 and the fourth piston ring 16 cooperate with each other to further scrape off the excess engine oil on the inner wall of the cylinder liner 12.

[0034] In addition, when the first piston ring 13, the second piston ring 14, the fourth piston ring 16 and the third piston ring 15 abut against the inner wall of the cylinder liner 12, they can also transfer most of the heat absorbed by the piston 11 to the cylinder wall and be taken away by the cooling water, thereby ensuring the thermal balance of the piston 11.

[0035] Please refer to FIG. 1 and FIG. 3. In some embodiments, the third piston ring 15 includes but is not limited to a three-piece combined oil ring structure, a spiral spring oil ring structure or a nose ring structure, etc., which can be flexibly adjusted and set according to actual needs, as long as it can play a role in sealing and isolating oil, and no specific limitation is made here. In this embodiment, the third piston ring 15 specifically adopts a three-piece combined oil ring structure. Compared with the spiral spring oil ring structure or the nose ring structure, the elastic force of the piston ring 11 is greatly increased, and at the same time, it can achieve elastic sealing on the two opposite sides of the third annular groove 1113 along the reciprocating motion direction, greatly eliminating the initial channel area of ​​oil leakage, and greatly reducing the possibility of oil being sucked into the combustion chamber under the intake negative pressure.

[0036] Please refer to FIG. 1 and FIG. 3. In one embodiment, when the third piston ring 15 is configured as a three-piece combined oil ring structure, the third piston ring 15 includes an annular elastic seat 151 and two annular elastic sheets 152. The elastic seat 151 abuts against the bottom wall of the third annular groove 1113, and a part of the structure of the elastic seat 151 extends out of the third annular groove 1113 and abuts against the inner wall of the cylinder sleeve 12. The two elastic sheets 152 are respectively connected to the two opposite end surfaces of the elastic seat 151 along the reciprocating motion direction, and each elastic sheet 152 extends out of the third annular groove 1113 and abuts against the inner wall of the cylinder sleeve 12. And the length of the portion of each elastic sheet 152 extending out of the third annular groove 1113 is greater than the length of the portion of the elastic seat 151 extending out of the third annular groove 1113. In this way, the elastic seat 151 and the two elastic sheets 152 abut against the inner wall of the cylinder sleeve 12, and have good sealing performance. In addition, since the thickness of the elastic sheet 152 is less than that of the elastic seat 151, the elastic sheet 152 is more easily deformed when subjected to force, so that the length of the portion of the elastic sheet 152 extending to the outside of the third annular groove 1113 is greater than the length of the portion of the elastic seat 151 extending to the outside of the third annular groove 1113, thereby preventing the elastic seat 151 from extending to the outside of the third annular groove 1113 from being too long and causing a movement jam defect. This not only has better sealing performance, but also facilitates the reciprocating motion of the piston 11. At the same time, the two elastic sheets 152 effectively scrape off excess lubricating oil on the inner wall of the cylinder liner 12 when the piston 11 moves downward.

[0037] It should be noted that the thickness of the elastic seat 151 refers to the distance between two opposite end surfaces of the elastic seat 151 along the reciprocating motion direction.

[0038] In some embodiments, the elastic sheet 152 includes but is not limited to a metal sheet, which is elastic, high temperature resistant and has a long service life.

[0039] Please refer to FIG. 1 and FIG. 2. In some embodiments, the elastic seat 151 includes a main body ring 1511 and an elastic abutment portion 1512 connected to the main body ring 1511. Specifically, the main body ring 1511 and the elastic abutment portion 1512 are an integrated structure, including but not limited to being integrally formed by a die-casting process, a sheet metal process or a welding process. Among them, the main body ring 1511 is provided with mounting portions at opposite ends along the reciprocating motion direction, and each elastic sheet 152 is correspondingly mounted on each mounting portion. Optionally, the elastic sheet 152 includes but is not limited to being fixedly connected to the mounting portion by bonding, clamping, welding, or fasteners such as pins, rivets or screws. Among them, the mounting portion is, for example, set in a step, and the elastic sheet 152 is mounted on the step, and the step plays a limiting role on the elastic sheet 152, so that the elastic sheet 152 can be quickly and stably mounted on the main body. In addition, the elastic sheet 152 and the elastic seat 151 can be made of the same or different materials according to actual needs, and can be assembled together.

[0040] On the basis of the above-mentioned embodiment, the elastic abutment portion 1512 includes a spring sheet that is reciprocatingly bent along the radial direction of the third piston ring 15. Specifically, the cross section of the elastic abutment portion 1512 along the radial direction of the third piston ring 15 is, for example, S-shaped, trigonometric function curve, Z-shaped or W-shaped. In this way, the elastic abutment portion 1512 has good elasticity, and the elastic sheet 152 can always abut against the inner wall of the cylinder sleeve 12 when the piston 11 drives the third piston ring 15 to reciprocate inside the cylinder sleeve 12, which can adapt to the good sealing of the cylinder sleeve 12 with different inner diameters in the axial direction, and effectively prevent oil leakage.

[0041] In one embodiment, the radial cross section of the first piston ring 13 includes, but is not limited to, a trapezoidal barrel surface, a rectangular shape, a pentagon, a hexagon, an octagon, an ellipse or other regular and irregular shapes, and can be flexibly adjusted and set according to actual needs. In this embodiment, the radial cross section of the first piston ring 13 is specifically set to a trapezoidal barrel surface, in other words, an isosceles trapezoid, the upper bottom surface of the isosceles trapezoid faces the bottom of the first annular groove 1111, and the lower bottom of the isosceles trapezoid abuts against the inner wall surface of the cylinder sleeve 12, which not only has a good sealing effect, but also facilitates the generated carbon deposits to flow to the inside of the cylinder sleeve 12 along the direction shown by the arrow in Figure 2, which can prevent the piston 11 from being stuck when the carbon deposits cannot be discharged.

[0042] Please refer to FIG. 1 and FIG. 2 . On the basis of the above-mentioned embodiment, the side of the second piston ring 14 facing the cylinder liner 12 is set as an anti-twisted cone. In addition, the fourth piston ring 16 includes a nose-shaped portion facing the inner wall of the cylinder liner 12, and the side of the nose-shaped portion facing the cylinder liner 12 is provided with a positive twisted cone. In this way, the positive twisted cone and the anti-twisted cone cooperate with each other to achieve a better sealing effect. At the same time, when the nose-shaped portion reciprocates up and down along the inner wall of the cylinder liner 12, it is convenient to scrape off the carbon deposits on the inner wall of the cylinder liner 12 and discharge it downward.

[0043] Of course, as some optional solutions, the side of the second piston ring 14 facing the cylinder liner 12 and the side of the fourth piston ring 16 facing the cylinder liner 12 are both set as anti-twisted cones. As some optional solutions, the second piston ring 14 includes a nose-shaped portion facing the inner wall of the cylinder liner 12, and the fourth piston ring 16 includes a nose-shaped portion facing the inner wall of the cylinder liner 12.

[0044] In some embodiments, the present application also provides a diesel engine, which includes the piston assembly 10 of any of the above embodiments.

[0045] In some embodiments, the present application also provides a vehicle, which includes the diesel engine in the above embodiment.

[0046] In the above-mentioned diesel engine and vehicle, the first annular groove 1111 and the second annular groove 1112 are arranged on the head 111, and the third annular groove 1113 is arranged on the skirt 112. Compared with the method of forming three annular grooves on the outer wall of the head 111 in the related art, the third annular groove 1113 is specifically an oil ring groove, which is close to the oil pan and relatively farther away from the head 111, that is, farther away from the high temperature area of ​​the head 111. In this way, the temperature of the third annular groove 1113 is lower than the temperature of the annular groove of the head 111, thereby greatly avoiding the occurrence of oil coking and carbon deposition in the third annular groove 1113, thereby reducing the wear of the piston 11 ring and greatly extending the service life of the piston 11 ring and the piston assembly 10.

[0047] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0048] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0049] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0050] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0051] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0052] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0053] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A piston for being reciprocatingly slidably disposed in a cylinder liner of an internal combustion engine cylinder, characterized in that: The piston comprises: A head, wherein a first annular groove and a second annular groove are sequentially arranged along the reciprocating sliding direction on the outer wall of the head, wherein the first annular groove is arranged around the circumference of the head and is used to install a first piston ring, and the second annular groove is arranged around the circumference of the head and is used to install a second piston ring; and A skirt portion is connected to the head portion, a third annular groove is formed on the outer wall of the skirt portion, the third annular groove is arranged around the circumference of the skirt portion and is used to install a third piston ring.

2. The piston according to claim 1, characterized in that A fourth annular groove is also formed on the outer wall of the head, which is arranged circumferentially around the head and is used to install a fourth piston ring. The first annular groove, the second annular groove, the fourth annular groove and the third annular groove are arranged in sequence along the reciprocating sliding direction.

3. A piston assembly, characterized in that: The piston assembly includes the piston as described in claim 1, and also includes a cylinder liner, a first piston ring, a second piston ring and a third piston ring. The piston is reciprocatingly slidably arranged in the cylinder liner, the first piston ring is arranged in the first annular groove, the second piston ring is arranged in the second annular groove, and the third piston ring is arranged in the third annular groove. The first piston ring, the second piston ring and the third piston ring are all used to abut and cooperate with the inner wall of the cylinder liner and can slide against each other with the reciprocating motion of the piston.

4. The piston assembly according to claim 3, characterized in that: The piston assembly also includes a fourth piston ring. A fourth annular groove is also formed on the outer wall of the head. The fourth annular groove is arranged circumferentially around the head and is used to install the fourth piston ring. The first annular groove, the second annular groove, the fourth annular groove and the third annular groove are arranged in sequence along the reciprocating sliding direction.

5. The piston assembly according to claim 4, characterized in that: The third piston ring includes a three-piece combined oil ring structure, a spiral spring type oil ring structure or a nose type ring structure.

6. The piston assembly according to claim 5, characterized in that: When the third piston ring is set as a three-piece combined oil ring structure, the third piston ring includes an annular elastic seat and two elastic sheets arranged in an annular shape; the elastic seat abuts against the bottom wall of the third annular groove, and a partial structure of the elastic seat extends to the outside of the third annular groove and abuts and cooperates with the inner wall of the cylinder liner; the two elastic sheets are respectively connected to the two opposite end surfaces of the elastic seat along the reciprocating motion direction, and each of the elastic sheets extends to the outside of the third annular groove and abuts and cooperates with the inner wall of the cylinder liner; and the length of the portion of each elastic sheet extending to the outside of the third annular groove is greater than the length of the portion of the elastic seat extending to the outside of the third annular groove.

7. The piston assembly according to claim 6, characterized in that: The elastic seat includes a main body ring and an elastic abutment portion connected to the main body ring; the main body ring is provided with mounting portions at two opposite ends along the reciprocating motion direction, and each elastic sheet is correspondingly mounted on each mounting portion; the elastic abutment portion includes a spring sheet that is reciprocatingly bent along the radial direction of the third piston ring.

8. The piston assembly according to claim 4, characterized in that: The radial cross section of the first piston ring is set as a trapezoidal barrel surface; the side of the second piston ring facing the cylinder liner is set as an anti-distorted cone surface, and the fourth piston ring includes a nose-shaped portion facing the inner wall of the cylinder liner, and the side of the nose-shaped portion facing the cylinder liner is provided with a positive twisted cone surface; Alternatively, the side surface of the second piston ring facing the cylinder liner and the side surface of the fourth piston ring facing the cylinder liner are both configured as anti-twisted conical surfaces; Alternatively, the second piston ring includes a nose-shaped portion disposed facing the inner wall of the cylinder liner, and the fourth piston ring includes a nose-shaped portion disposed facing the inner wall of the cylinder liner.

9. A diesel engine, characterized in that: The diesel engine comprises the piston assembly according to any one of claims 3 to 9.

10. A vehicle, characterized in that: The vehicle includes the diesel engine as claimed in claim 9.

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