Lightweight forged steel piston

Abstract

The invention relates to the technical field of pistons, and provides a lightweight forged steel piston which comprises a piston head, a piston skirt and a piston pin seat, and is characterized in that a piston face window is formed in the piston skirt and provided with a fence type weight reduction cavity, and the fence type weight reduction cavity is located above a piston pin hole; the fence type weight reduction cavity penetrates through the piston skirt part in the direction of the piston pin hole; two sides of the piston pin hole are respectively provided with a main thrust side skirt wall and a secondary thrust side skirt wall, and the center of the piston pin hole is deviated towards the main thrust side skirt wall; the outer circle of a piston skirt part which is circumferentially connected with the piston outer pin seat and the piston face window is retracted inwards and is in smooth transition connection with the main thrust side skirt wall and the secondary thrust side skirt wall respectively; and the thickness of the main thrust side skirt wall is greater than that of the secondary thrust side skirt wall. According to the technical scheme, the weight of the piston is reduced, meanwhile, noise and vibration generated when the diesel engine works are reduced, meanwhile, the cooling effect is good, and movement of the piston in the air cylinder is more stable.

Description

Technical Field

[0001] The present invention relates to the technical field of pistons, and in particular to a lightweight forged steel piston. Background Art

[0002] During the reciprocating motion of the piston in the engine, mechanical load, thermal load, friction loss, harsh working environment and unreasonable piston design not only affect the service life of the piston, but also seriously affect the combustion and thermal efficiency of the engine. In the related technology, the weight of the piston is generally reduced by designing weight-reducing holes on the back of the piston. The piston skirt often adopts a symmetrical structure, the piston pin hole is often designed in its center, and the cooling oil cavity inside the piston head and skirt is smooth. However, it is still easy to generate loud noise and vibration, and the cooling effect is poor, which cannot meet the needs of high-power and high-load diesel engines. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0004] To this end, an object of the present invention is to provide a lightweight forged steel piston that can be suitable for high-power, high-load diesel engines, has lower emissions, and has a high piston structure strength. While reducing the weight of the piston, it also reduces the noise and vibration generated when the diesel engine is working. At the same time, the cooling effect is good and the movement of the piston in the cylinder is more stable.

[0005] In order to achieve the above-mentioned purpose, the technical solution of the present invention provides a lightweight forged steel piston, including a piston head, a piston skirt and a piston pin seat, the piston skirt is provided with a piston face window, the piston face window is provided with a fence-type weight-reducing cavity, the fence-type weight-reducing cavity is located above the piston pin hole, and the fence-type weight-reducing cavity passes through the piston skirt along the direction of the piston pin hole; the two sides of the piston pin hole are respectively the main thrust side skirt wall and the secondary thrust side skirt wall, and the center of the piston pin hole is offset toward the main thrust side skirt wall; the outer circle of the piston skirt circumferentially connected to the piston outer pin seat and the piston face window is indented inward and is smoothly transitionally connected to the main thrust side skirt wall and the secondary thrust side skirt wall respectively; the thickness of the main thrust side skirt wall is greater than the thickness of the secondary thrust side skirt wall.

[0006] Preferably, the distance between the center line of the piston pin hole and the center line of the piston is 0.3 mm-1.0 mm.

[0007] Preferably, the difference between the thickness of the primary thrust side skirt wall and the thickness of the secondary thrust side skirt wall is 1.0-2.0 mm.

[0008] Preferably, the multiple cavities of the fence-type weight-reducing cavity are evenly distributed in an arc shape above the piston pin hole.

[0009] Preferably, the centripetal angle between two adjacent cavities in the fence-type weight-reducing cavity is 15°-25°.

[0010] Preferably, each cavity in the fence-type weight-reducing cavity has the same size and the inner wall is a smooth arc shape, wherein the upper and lower inner walls are bent toward the center of the piston pin hole, and the left and right inner walls are symmetrically bent toward the inside of the cavity, and the centripetal angle of the connected side walls of two adjacent cavities is 10°-20°.

[0011] Preferably, reinforcing ribs are provided on the connected side walls of two adjacent cavities, and the reinforcing ribs connect the top of the fence-type weight-reducing cavity and the top of the piston outer pin seat.

[0012] Preferably, an inner cooling oil chamber is arranged between the piston head and the piston skirt, and two annular petal protrusions are arranged inside the inner cooling oil chamber, wherein one annular petal protrusion protrudes from the inner side wall of the inner cooling oil chamber close to the center of the piston toward the inside thereof, and is recorded as annular petal protrusion I, and the other annular petal protrusion protrudes from the inner side wall of the inner cooling oil chamber away from the center of the piston toward the inside thereof, and is recorded as annular petal protrusion II, and the annular petal protrusion I and the annular petal protrusion II are staggered up and down, and the position of the annular petal protrusion II is not lower than the position of the annular petal protrusion I.

[0013] Preferably, an oil outlet hole and an oil inlet hole are arranged inside the piston skirt, and the oil outlet hole and the oil inlet hole are arranged in a ring shape, are spaced 180 degrees apart, and are connected to the inner cooling oil cavity.

[0014] Preferably, a combustion chamber is arranged on the top surface of the piston head, a piston ring groove is arranged circumferentially of the piston head, an oil return hole is arranged at the bottom of the lowest piston ring groove, an oil unloading hole is arranged in the top ring groove area of ​​the piston skirt, and the oil unloading hole is arranged adjacent to the oil return hole.

[0015] The lightweight forged steel piston proposed by the present invention has the following beneficial technical effects:

[0016] (1) The lightweight forged steel piston proposed in the present invention can meet the lightweight requirements, and at the same time the structural strength of the piston is improved, which can effectively improve the performance of the engine.

[0017] (2) The thickness of the main thrust side skirt wall in a lightweight forged steel piston proposed by the present invention is greater than that of the secondary thrust side skirt wall. The asymmetric structural design of the piston skirt reduces the weight of the piston while making the movement of the piston in the cylinder more stable, thereby reducing the noise and vibration generated by the rough operation of traditional diesel engines. The main thrust side skirt wall is relatively thick, which can better withstand the huge pressure and lateral force generated during the combustion process, making the movement of the piston in the cylinder more stable, reducing the deformation of the piston under high load conditions, and helping to maintain good sealing between the piston and the cylinder wall. The secondary thrust side skirt wall is relatively thin, which can reduce the mass of the piston, thereby reducing the inertial force of reciprocating motion, which is beneficial to reduce vibration when the engine is running at high speed, improve engine response speed, reduce energy loss, and improve fuel economy.

[0018] (3) The center of the piston pin hole in a lightweight forged steel piston proposed by the present invention is offset toward the main thrust side skirt wall. During the operation of the engine, the piston moves up and down in the cylinder and will swing due to the action of the connecting rod. When the piston pin seat and the pin hole are offset, the piston will have a slow rotation process during the working stroke. During the power stroke, the offset distance allows the piston to transition more smoothly from one side to the other under the action of the side pressure, reducing the impact of the piston on the cylinder wall, thereby reducing the piston knocking noise. At the same time, this design also helps to improve the wear between the piston and the cylinder wall, making the contact and friction between the piston and the cylinder wall more uniform, extending their service life, and improving the reliability of the engine operation.

[0019] (4) The lightweight forged steel piston proposed in the present invention forms a flexible open elastic structure with the piston pin seat through the design of a fence-type weight-reducing cavity, which can effectively reduce the stress concentration of the piston pin seat. When the engine is working, the piston will be affected by multiple complex forces such as gas pressure and inertia force. The flexible open elastic structure can buffer the bending deformation and elliptical deformation of the piston pin through its own elastic deformation, just like an elastic protective cover, avoiding damage to the piston due to excessive local stress. At the same time, it can better adapt to the thermal expansion of the piston pin seat during operation. Because the temperature will rise when the engine is working, the piston parts will expand due to heat. The elastic structure can provide a certain space for this expansion, thereby preventing the piston from getting stuck due to thermal expansion and ensuring that the piston and the piston pin can work normally.

[0020] (5) The lightweight forged steel piston proposed by the present invention increases the heat dissipation surface area inside the piston through the inside-outside penetrating design of the fence-type weight-reducing cavity, and can more effectively conduct heat to the center and skirt of the piston. The design of the fence-type weight-reducing cavity can guide the path of heat flow, so that the heat can be better dispersed inside the piston, avoiding local overheating, so that the piston can work stably in a high temperature environment and extend the service life of the piston.

[0021] (6) The lightweight forged steel piston proposed in the present invention reduces the weight of the piston through the design of a fence-type weight-reducing cavity, thereby reducing the inertia force of the piston itself. In this way, when the engine is running at a high speed, the inertia load of the piston moving parts can be effectively reduced, making the engine run more smoothly and reducing vibration. At the same time, the energy loss of the engine caused by the inertia force is reduced, thereby improving fuel economy.

[0022] (7) The lightweight forged steel piston proposed in the present invention is designed with reinforcing ribs between the fence-type weight-reducing cavity and the piston outer pin seat. First, it enhances the structural strength. During the operation of the piston, it will bear huge mechanical and thermal loads. The reinforcing ribs can effectively disperse the force on the pin seat to the entire piston structure, including the surface window fence-type inside and outside the weight-reducing cavity surrounding part, disperse the force transmission, prevent local damage due to excessive force, improve the overall structural rigidity of the piston, and ensure that the piston will not be easily deformed under complex working conditions (such as high speed, high explosion pressure). Second, it improves the efficiency of heat conduction. When the engine is working, the temperature distribution of various parts of the piston is uneven, and the temperature at the pin seat is higher. The reinforcing ribs can serve as a bridge for heat conduction, and conduct the heat of the pin seat to the surrounding area more quickly, including the weight-reducing cavity part, so that the heat can be better dissipated, which helps to maintain the uniformity of the overall temperature of the piston, avoid local overheating, and ensure the normal operation of the piston.

[0023] (8) The lightweight forged steel piston proposed in the present invention is designed with an inner cooling oil chamber with an annular petal protrusion between the piston head and the piston skirt, which improves the vibration effect of the cooling oil, increases the contact area with the cooling oil, and further improves the heat transfer efficiency, thereby further enhancing the cooling effect of the piston.

[0024] (9) The oil outlet hole and the oil inlet hole of a lightweight forged steel piston proposed by the present invention are arranged at 180 degrees, ensuring that the cooling oil entering from the oil inlet hole can be smoothly diffused in the inner cooling oil cavity with petal protrusions to form a good cooling oil channel, ensuring that the cooling oil can fully contact and flow in all parts of the cavity, so that the cooling oil can form effective convection between the protrusions, and then flow out from the oil outlet hole after flowing through all parts.

[0025] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0027] Figure 1 A schematic structural diagram of a lightweight forged steel piston according to an embodiment of the present invention is shown;

[0028] Figure 2 A schematic structural diagram of a lightweight forged steel piston according to an embodiment of the present invention is shown;

[0029] Figure 3 A schematic diagram of the front structure of a lightweight forged steel piston according to an embodiment of the present invention is shown;

[0030] Figure 4 A bottom view structural diagram of a lightweight forged steel piston according to an embodiment of the present invention is shown;

[0031] Figure 5 A schematic cross-sectional view of a lightweight forged steel piston according to an embodiment of the present invention is shown.

[0032] in, Figures 1 to 5 The corresponding relationship between the reference numerals and the components is as follows:

[0033] 102 piston head, 1021 combustion chamber, 1022 piston ring groove, 1023 oil return hole, 104 piston skirt, 1041 piston face window, 1042 fence type weight reduction cavity, 1042-1 cavity, 1042-2 upper inner wall, 1042-3 lower inner wall, 1042-4 left inner wall, 1042-5 right inner wall, 1042-6 connected side wall, 1042-7 reinforcement rib, 1043 piston pin hole, 1044 main thrust side skirt wall, 1045 secondary thrust side skirt wall, 1046 oil unloading hole, 106 piston pin seat, 1061 piston outer pin seat, 108 piston pin hole center line, 110 piston center line, 112 inner cooling oil cavity, 114 annular petal protrusion I, 116 annular petal protrusion II, 118 oil outlet hole, 120 oil inlet hole. DETAILED DESCRIPTION

[0034] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0035] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0036] Combine the following Figures 1 to 5 A lightweight forged steel piston according to an embodiment of the present invention is described in detail.

[0037] like Figures 1 to 5As shown, a lightweight forged steel piston according to an embodiment of the present invention comprises: a piston head 102, a piston skirt 104 and a piston pin seat 106, the piston skirt 104 is provided with a piston face window 1041, the piston face window 1041 is provided with a fence-type weight-reducing cavity 1042, the fence-type weight-reducing cavity 1042 is located above the piston pin hole 1043, and the fence-type weight-reducing cavity 1042 penetrates the piston skirt 104 along the direction of the piston pin hole 1043, which can reduce the weight of the piston by 10%-15%, thereby reducing the inertial force of the piston itself, so that when the engine is running at a high speed, the inertial load of the piston moving parts can be effectively reduced, so that the engine runs more smoothly, reduces vibration, and reduces the energy loss of the engine caused by the inertial force, thereby improving fuel economy. At the same time, the internal and external penetration design increases the heat dissipation surface area inside the piston, and can make the heat more effectively transferred to the center and skirt of the piston. The design of the fence-type weight-reducing cavity 1042 can guide the path of heat flow, so that the heat can be better dispersed inside the piston and local overheating can be avoided, so that the piston can work stably in a high temperature environment and the service life of the piston can be extended.

[0038] The two sides of the piston pin hole 1043 are respectively the main thrust side skirt wall 1044 and the secondary thrust side skirt wall 1045, and the center of the piston pin hole 1043 is offset toward the main thrust side skirt wall 1044; the outer circle of the piston skirt 104 circumferentially connected to the piston outer pin seat 1061 and the piston face window 1041 is retracted inward and is smoothly transitionally connected to the main thrust side skirt wall 1044 and the secondary thrust side skirt wall 1045 respectively; the thickness of the main thrust side skirt wall 1044 is greater than that of the secondary thrust side skirt wall 1045, which reduces the weight of the piston and achieves lightweight piston while meeting the requirements of structural strength.

[0039] Furthermore, if Figure 3 As shown, the distance t between the center line 108 of the piston pin hole and the center line 110 of the piston is 0.3mm-1.0mm, preferably 0.3mm-0.8mm. During the operation of the engine, the piston moves up and down in the cylinder, and swings due to the action of the connecting rod. When the piston pin seat 106 and the pin hole are offset, the piston will have a slow rotation process in the working stroke. In the power stroke, the offset distance allows the piston to transition more smoothly from one side to the other side under the action of the side pressure, reducing the impact of the piston on the cylinder wall, thereby reducing the piston knocking noise. At the same time, this design also helps to improve the wear between the piston and the cylinder wall, making the contact and friction between the piston and the cylinder wall more uniform, extending their service life, and improving the reliability of the engine operation.

[0040] Furthermore, the difference between the thickness b of the main thrust side skirt wall 1044 and the thickness a of the secondary thrust side skirt wall 1045 is 1.0-2.0 mm. The inner wall of the piston skirt 104 is an eccentric circle structure, and the wall thickness is uniformly thinned. The asymmetric structural design of the piston skirt 104 reduces the weight of the piston while making the movement of the piston in the cylinder more stable, thereby reducing the noise and vibration generated by the rough operation of the traditional diesel engine. The main thrust side skirt wall 1044 is relatively thick, which can better withstand the huge pressure and lateral force generated during the combustion process, making the movement of the piston in the cylinder more stable, reducing the deformation of the piston under high load conditions, and helping to maintain good sealing between the piston and the cylinder wall. The secondary thrust side skirt wall 1045 is relatively thin, which can reduce the mass of the piston, thereby reducing the inertial force of reciprocating motion, which is conducive to reducing vibration when the engine is running at high speed, improving the engine response speed, and reducing energy loss, and improving fuel economy.

[0041] Furthermore, if Figure 3 As shown, the multiple cavities 1042-1 of the fence-type weight-reducing cavity 1042 are evenly distributed in an arc shape above the piston pin hole 1043. The centripetal angle α of two adjacent cavities 1042-1 in the fence-type weight-reducing cavity 1042 is 15°-25°.

[0042] Thus, the weight-reducing cavity and the piston pin seat 106 form a flexible open elastic structure, which can effectively reduce the stress concentration of the piston pin seat 106. When the engine is working, the piston will be affected by multiple complex forces such as gas pressure and inertia force. The flexible open elastic structure can buffer the bending deformation and elliptical deformation of the piston pin through its own elastic deformation, just like an elastic protective cover, to avoid damage to the piston due to excessive local stress. At the same time, it can better adapt to the thermal expansion of the piston pin seat 106 during operation. Because the temperature will rise when the engine is working, the piston parts will expand due to heat. The elastic structure can provide a certain space for this expansion, thereby preventing the piston from getting stuck due to thermal expansion and ensuring that the piston and the piston pin can work normally.

[0043] Furthermore, if Figure 3 As shown, each cavity 1042-1 in the fence-type weight-reducing cavity 1042 has the same size, and the inner wall is in a smooth arc shape, wherein the upper inner wall 1042-2 and the lower inner wall 1042-3 are bent toward the center of the piston pin hole 1043, the left inner wall 1042-4 and the right inner wall 1042-5 are symmetrically bent toward the inner side of the cavity 1042-1, and the centripetal angle β of the connected side walls 1042-6 of two adjacent cavities 1042-1 is 10°-20°. Thus, it is ensured that the weight-reducing cavity space is large enough and the structural strength of the piston is also ensured.

[0044] Furthermore, if Figure 3As shown, reinforcing ribs 1042-7 are provided on the connected side walls 1042-6 of the two adjacent cavities 1042-1, and the reinforcing ribs 1042-7 connect the top of the fence-type weight-reducing cavity 1042 and the top of the piston outer pin seat 1061. First, the structural strength is enhanced. During the operation of the piston, it will bear huge mechanical and thermal loads. The reinforcing ribs 1042-7 can effectively disperse the force exerted on the pin seat to the entire piston structure, including the surface window fence-type inside and outside penetrating the surrounding part of the weight-reducing cavity, disperse the force and prevent local damage due to excessive force, improve the overall structural rigidity of the piston, and ensure that the piston will not be easily deformed under complex working conditions (such as high speed and high explosion pressure). Second, the heat conduction efficiency is improved. When the engine is working, the temperature distribution of various parts of the piston is uneven, and the temperature at the pin seat is relatively high. The reinforcing rib 1042-7 can serve as a bridge for heat conduction, conducting the heat of the pin seat to the surrounding area, including the weight-reducing cavity, more quickly, so that the heat can be better dissipated, which helps to maintain the uniformity of the overall temperature of the piston, avoid local overheating, and ensure the normal operation of the piston.

[0045] Furthermore, if Figure 5 As shown, an inner cooling oil chamber 112 is provided between the piston head 102 and the piston skirt 104, and two annular petal protrusions are provided inside the inner cooling oil chamber 112, wherein one annular petal protrusion protrudes from the inner side wall of the inner cooling oil chamber 112 close to the center of the piston toward the inside thereof, which is recorded as annular petal protrusion I114, and the other annular petal protrusion protrudes from the inner side wall of the inner cooling oil chamber 112 away from the center of the piston toward the inside thereof, which is recorded as annular petal protrusion II116, and the annular petal protrusion I114 and the annular petal protrusion II116 are staggered up and down, and the position of the annular petal protrusion II116 is not lower than the position of the annular petal protrusion I114. The design of the inner cooling oil chamber 112 with annular petal protrusions improves the vibration effect of the cooling oil, increases the contact area with the cooling oil, and further improves the heat transfer efficiency, thereby further strengthening the cooling effect of the piston.

[0046] Furthermore, if Figure 4 As shown, an oil outlet hole 118 and an oil inlet hole 120 are arranged inside the piston skirt 104. The oil outlet hole 118 and the oil inlet hole 120 are arranged in a ring shape, the two are spaced 180 degrees apart, and are connected to the inner cooling oil cavity 112, thereby ensuring that the cooling oil entering from the oil inlet hole 120 can be smoothly diffused in the inner cooling oil cavity 112 with petal protrusions, forming a good cooling oil channel, ensuring that the cooling oil can fully contact and flow in all parts of the cavity, so that the cooling oil can form effective convection between the protrusions, and then flow out from the oil outlet hole 118 after flowing through all parts.

[0047] Furthermore, if Figure 5As shown, a combustion chamber 1021 is arranged on the top surface of the piston head 102, a piston ring groove 1022 is arranged circumferentially of the piston head 102, an oil return hole 1023 is arranged at the bottom of the lowest piston ring groove 1022, an oil unloading hole 1046 is arranged in the top ring groove area of ​​the piston skirt 104, and the oil unloading hole 1046 is arranged adjacent to the oil return hole 1023.

[0048] In addition, the piston ring groove 1022, which is the first ring groove at the top, can be made of the piston body material. If the explosion pressure, specific power, compression ratio and other parameters are large, a cast iron ring structure is used to strengthen the first ring groove.

[0049] The piston materials used are 38MnVS6, 42CrMoA, and 42CrMoA.

[0050] In the present invention, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance; the term "plurality" refers to two or more, unless otherwise clearly defined. The terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. 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.

[0051] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by terms such as “upper”, “lower”, “left”, “right”, “front” and “back” are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or unit referred to must have a specific direction, be constructed and operated in a specific orientation, and therefore, cannot be understood as a limitation on the present invention.

[0052] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A lightweight forged steel piston, comprising a piston head, a piston skirt and a piston pin seat, characterized in that: The piston skirt is provided with a piston face window, and the piston face window is provided with a fence-type weight-reducing cavity, and the fence-type weight-reducing cavity is located above the piston pin hole, and the fence-type weight-reducing cavity passes through the piston skirt along the direction of the piston pin hole; the two sides of the piston pin hole are respectively the main thrust side skirt wall and the secondary thrust side skirt wall, and the center of the piston pin hole is offset toward the main thrust side skirt wall; the outer circle of the piston skirt circumferentially connected to the piston outer pin seat and the piston face window is indented inwardly and is smoothly transitionally connected to the main thrust side skirt wall and the secondary thrust side skirt wall respectively; the thickness of the main thrust side skirt wall is greater than the thickness of the secondary thrust side skirt wall.

2. The lightweight forged steel piston according to claim 1, characterized in that: The distance between the center line of the piston pin hole and the center line of the piston is 0.3mm-1.0mm.

3. The lightweight forged steel piston according to claim 1, characterized in that: The difference between the thickness of the main thrust side skirt wall and the thickness of the secondary thrust side skirt wall is 1.0-2.0 mm.

4. The lightweight forged steel piston according to claim 1, characterized in that: The multiple cavities of the fence-type weight-reducing cavity are evenly distributed in an arc shape above the piston pin hole.

5. The lightweight forged steel piston according to claim 4, characterized in that: The centripetal angle of two adjacent cavities in the fence-type weight-reducing cavity is 15°-25°.

6. The lightweight forged steel piston according to claim 5, characterized in that: Each cavity in the fence-type weight-reducing cavity has the same size and the inner wall is a smooth arc shape, wherein the upper and lower inner walls are bent toward the center of the piston pin hole, and the left and right inner walls are symmetrically bent toward the inside of the cavity, and the centripetal angle of the connected side walls of two adjacent cavities is 10°-20°.

7. The lightweight forged steel piston according to claim 6, characterized in that: Reinforcing ribs are arranged on the connected side walls of two adjacent cavities, and the reinforcing ribs connect the top of the fence-type weight-reducing cavity and the top of the piston outer pin seat.

8. The lightweight forged steel piston according to any one of claims 1 to 7, characterized in that: An inner cooling oil chamber is arranged between the piston head and the piston skirt, and two annular petal protrusions are arranged inside the inner cooling oil chamber, wherein one annular petal protrusion protrudes from the inner side wall of the inner cooling oil chamber close to the center of the piston toward the inside thereof, and is recorded as annular petal protrusion I, and the other annular petal protrusion protrudes from the inner side wall of the inner cooling oil chamber away from the center of the piston toward the inside thereof, and is recorded as annular petal protrusion II. The annular petal protrusion I and the annular petal protrusion II are staggered up and down, and the position of the annular petal protrusion II is not lower than the position of the annular petal protrusion I.

9. The lightweight forged steel piston according to claim 8, characterized in that: An oil outlet hole and an oil inlet hole are arranged inside the piston skirt. The oil outlet hole and the oil inlet hole are arranged in a ring shape, are spaced 180 degrees apart, and are connected to the inner cooling oil cavity.

10. The lightweight forged steel piston according to claim 9, characterized in that: A combustion chamber is arranged on the top surface of the piston head, a piston ring groove is arranged circumferentially of the piston head, an oil return hole is arranged at the bottom of the lowest piston ring groove, an oil unloading hole is arranged in the top ring groove area of ​​the piston skirt, and the oil unloading hole is arranged adjacent to the oil return hole.

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