Piston for methanol engine and engine

Abstract

The piston comprises a first piston ring land close to a cylinder sleeve, and is characterized in that the piston is provided with a first piston ring groove used for assembling a first piston ring and a pressure relief groove formed in the first piston ring land, and the pressure relief groove is formed above the first piston ring groove; the first piston ring land comprises a boss located between the pressure relief groove and the first piston ring groove, an avoiding gap is formed between the boss and the cylinder sleeve, and impact airflow passes through the pressure relief groove and then flows to the first piston ring groove through the avoiding gap. According to the scheme, the pressure relief groove is formed in the first ring bank of the piston and located above the first piston ring groove, when the engine has the super detonation working condition, high-temperature and high-pressure gas descends to the pressure relief groove along the first ring bank of the piston, due to blocking of the boss below the pressure relief groove, the gas is guided to enter the pressure relief groove, and the pressure relief effect is improved. The pressure relief groove has a certain volume, gas flows in the pressure relief groove and then escapes, and the pressure reduction effect on pressure shock waves is achieved.

Description

Technical Field

[0001] This application belongs to the field of engine piston technology, specifically relating to a piston and engine for a methanol engine. Background Technology

[0002] The piston is an important component of the engine combustion chamber and has a significant impact on engine performance; it also withstands the combustion pressure in the cylinder and transmits the force to the connecting rod and crankshaft to achieve power output.

[0003] Pistons typically have three piston rings, primarily serving to seal, scrape, and distribute oil. The first piston ring is a compression ring, mainly used to seal the gas inside the cylinder to prevent leakage to the oil pan. In its free state, the piston ring's closed end is open by a certain distance; this is called the free opening. When the piston ring is assembled, it is in a rounded, tightened state, exerting a certain elastic force on the cylinder liner, ensuring a good fit between the ring and the cylinder liner. Given a fixed ring structure and material, the larger the free opening, the higher the ring elastic force, and vice versa.

[0004] Under the strategic framework of "carbon peaking" and "carbon neutrality," clean energy sources such as methanol and hydrogen have broad application prospects. Methanol engines, in particular, require less modification than traditional engines, offering significant improvements in both fuel economy and emissions while maintaining the original engine's power performance. Furthermore, as a clean alternative fuel for vehicle engines, methanol reduces air pollution. In addition, methanol is a liquid fuel that can utilize petroleum-based storage and transportation systems, thus requiring relatively less infrastructure investment and leading to its widespread adoption.

[0005] However, with the development and application of methanol engines, a problem arises: fuel knock impacts the first piston ring. Typically, there is a narrow gap between the first piston ring land and the cylinder liner. When there are high-frequency, ultra-high pressure fluctuations inside the cylinder, the pressure is transmitted to the piston rings through this gap. The piston rings cannot withstand the impact of the huge pressure waves and deform, resulting in a reduced free opening of the first piston ring. This leads to the ring becoming out of round and not fitting tightly with the cylinder liner, increasing cylinder leakage. It becomes difficult for an oil film to form between the cylinder wall and the piston rings, resulting in poor lubrication and even dry friction. This causes obvious longitudinal mechanical scratches and abrasions on the cylinder wall within the piston ring's range of motion. In severe cases, adhesive wear occurs, causing difficulty starting the engine or automatic stalling. Furthermore, dry friction leads to deep grooves on the cylinder wall, and the piston, piston rings, and cylinder wall lose their sealing properties during friction, resulting in reduced cylinder compression pressure and loss of power.

[0006] Therefore, the piston needs to be improved to prevent the high knock pressure wave from impacting the piston rings when the methanol engine knocks, which could cause the piston rings to deform, leading to large engine air leakage, engine oil spraying, or even cylinder scoring and other major reliability problems. Utility Model Content

[0007] This application provides a piston and engine for a methanol engine, which solves the problem of impact damage to the piston ring caused by high temperature and high pressure gas shock waves under engine knock conditions.

[0008] The technical solution adopted in this application is as follows:

[0009] A piston for a methanol engine, the piston including a first piston ring land near the cylinder liner, characterized in that the piston has a first piston ring groove for assembling a piston ring and a pressure relief groove disposed on the first piston ring land, the pressure relief groove being disposed above the first piston ring groove, the first piston ring land including a boss located between the pressure relief groove and the first piston ring groove, a clearance clearance being provided between the boss and the cylinder liner, the impinging airflow passing through the pressure relief groove and then through the clearance clearance to the first piston ring groove.

[0010] In a preferred implementation of a piston for a methanol engine, the volume d of the pressure relief groove satisfies: d≥P1 / P2*V;

[0011] Where: P1 is the peak cylinder pressure under engine knocking conditions, P2 is the maximum pressure value of the pressure shock wave that the piston ring can withstand after being relieved by the pressure relief groove, and V is the clearance volume between the piston first ring land and the cylinder liner.

[0012] In a preferred embodiment of a piston for a methanol engine, the opening of the pressure relief groove faces the cylinder liner, and an arc-shaped guide surface is provided at the opening on the upper wall of the pressure relief groove. In another preferred embodiment of a piston for a methanol engine, the upper edge of the boss forms the lower wall of the pressure relief groove, and the lower edge of the boss forms the upper wall of the first piston ring groove.

[0013] In a preferred implementation of a piston for a methanol engine, the piston first ring land further includes a first wall surface located above the pressure relief groove, the bottom of the first wall surface forming the upper groove wall of the pressure relief groove, and the outer wall surface of the boss protruding from the first wall surface and the outer wall surface of the first piston ring groove.

[0014] In a preferred embodiment of a piston for a methanol engine, the piston has a recessed portion arranged circumferentially to form an annular pressure relief groove.

[0015] In a preferred implementation of a piston for a methanol engine, the depth of the concave portion is not less than half the depth of the first piston ring groove.

[0016] In a preferred implementation of a piston for a methanol engine, the cross-section of the pressure relief groove is rectangular or U-shaped.

[0017] In a preferred embodiment of a piston for a methanol engine, the piston further includes a second piston ring groove located below the first piston ring groove, and the distance between the pressure relief groove and the first piston ring groove is greater than the distance between the first piston ring groove and the second piston ring groove.

[0018] This application also includes an engine, which includes a body and a cylinder, wherein the cylinder is provided with a piston as described above.

[0019] Due to the adoption of the above technical solution, the beneficial effects achieved by this application are as follows:

[0020] (1) The present application solution provides a pressure relief groove on the first ring land of the piston, and the pressure relief groove is located above the first piston ring groove. When the engine is in super knock condition, the high temperature and high pressure gas flows down along the first ring land of the piston to the pressure relief groove. Due to the blockage of the boss below the pressure relief groove, the gas is guided into the pressure relief groove. The pressure relief groove has a certain volume. After the gas flows inside the pressure relief groove, it escapes, thereby achieving the pressure reduction effect on the pressure wave. Moreover, the groove shape of the pressure relief groove makes the gas entering the pressure relief groove tend to roll out of the groove, thereby further offsetting the impact kinetic energy of the downward airflow. This is beneficial to alleviate the gas pressure reaching the first piston ring, thereby reducing the impact force of the gas on the first piston ring under knock condition.

[0021] Furthermore, creating a pressure relief groove above the first piston ring groove helps reduce the overall weight of the piston, thereby mitigating the impact of the piston against the cylinder liner. The pressure relief groove also increases the carbon storage capacity, preventing carbon buildup on the piston's first ring land that could lead to abnormal friction with the cylinder liner. This prevents excessive wear of the cylinder liner, which could increase clearance and consequently reduce abnormal oil consumption, thus further improving engine reliability.

[0022] (2) By calculating and limiting the minimum volume of the pressure relief groove, excessive weight reduction of the pressure relief groove can be avoided, which would affect the structural strength of the piston. This ensures the overall structural stability and application reliability of the piston while achieving pressure wave buffering. Among them, P1 and P2 are calculated based on the piston ring strength. This experimental calculation method changes the volume of the pressure relief groove, records the P2 value at different volumes, and records the degree of piston ring deformation under knocking conditions, thereby obtaining the minimum volume of the pressure relief groove.

[0023] (3) By setting the upper and lower edges of the boss to form the lower wall of the pressure relief groove and the upper wall of the first piston ring groove respectively, the forming and processing difficulty of the pressure relief groove is reduced, and the piston structure is simply modified. Furthermore, the outer wall of the boss protrudes above the first wall above the pressure relief groove and protrudes from the outer wall of the first piston ring groove. That is, the lower wall of the pressure relief groove protrudes from the upper wall of the pressure relief groove, and the upper wall of the first piston ring groove protrudes from the upper wall of the pressure relief groove. Thus, when the high-pressure airflow descends, the boss will have a certain blocking effect on the high-pressure airflow. Combined with the relatively inward-curving upper wall of the pressure relief groove, it is beneficial to introduce the high-pressure gas into the pressure relief groove first, avoiding the gas from directly impacting the piston ring located in the first piston ring groove, and further strengthening the protection effect on the piston ring. Attached Figure Description

[0024] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0025] Figure 1 This is a cross-sectional view of the piston in one embodiment of the present invention;

[0026] Figure 2 This is another schematic diagram of the piston in one embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures:

[0028] 100-Piston, 101-Pressure relief groove, 102-First piston ring groove, 103-Piston ring, 104-First piston ring land, 105-Boss, 106-Clearance clearance, 107-Second piston ring groove, 200-Cylinder liner. Detailed Implementation

[0029] To more clearly illustrate the overall concept of this application, a detailed explanation is provided below with reference to the accompanying drawings.

[0030] Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below. It should be noted that, unless otherwise specified, the embodiments of this application and the features thereof can be combined with each other.

[0031] Furthermore, it should be understood in the description of this application that the terms "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0032] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0033] In this application, unless otherwise expressly specified and limited, the "above" or "below" of the second feature can 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. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

[0034] This application provides a piston for a methanol engine, such as... Figure 1 , Figure 2 As shown, the piston 100 includes a first piston ring land 104 near the cylinder liner 200. The piston 100 is characterized by having a first piston ring groove 102 for assembling a piston ring 103 and a pressure relief groove 101 disposed on the first piston ring land 104. The pressure relief groove 101 is disposed above the first piston ring groove 102. The first piston ring land 104 includes a boss 105 located between the pressure relief groove 101 and the first piston ring groove 102. A clearance gap 106 is provided between the boss 105 and the cylinder liner 200. The impact airflow passes through the pressure relief groove 101 and then flows through the clearance gap 106 to the first piston ring groove 102.

[0035] This application solution provides a pressure relief groove 101 on the first piston ring land 104, with the groove 101 located above the first piston ring groove 102. During a super-knock condition, high-temperature, high-pressure gas flows down the first piston ring land 104 to the pressure relief groove 101. Due to the obstruction of the protrusion 105 below the groove 101, the gas is guided into the groove 101. The groove 101 has a certain volume, allowing the gas to flow inside and then escape, thus reducing pressure wave pressure. Furthermore, the groove shape of the groove 101 causes the gas entering the groove to tend to roll back out, further offsetting the impact kinetic energy of the downward airflow. This helps alleviate the pressure reaching the first piston ring 103, thereby reducing the impact force of the gas on the first piston ring 103 during knock conditions.

[0036] Furthermore, the pressure relief groove 101 above the first piston ring groove 102 helps reduce the overall weight of the piston 100, thereby mitigating the impact of the piston 100 on the cylinder liner 200. The pressure relief groove 101 also increases the carbon storage capacity, preventing carbon deposits from gradually accumulating on the piston's first ring land 104 and causing abnormal friction with the cylinder liner 200. This prevents excessive wear of the cylinder liner 200, which could lead to increased clearance and consequently, increased abnormal oil consumption, further improving engine reliability.

[0037] It should be noted that, due to the knocking characteristics of methanol fuel, the pressure relief tank 101 will not store too much carbon or fill it completely. Moreover, while the pressure relief tank 101 continuously alleviates knocking and reverses the knocking impact, it is also constantly impacted. The carbon deposits will be knocked off and carried away from the pressure relief tank 101 by the movement and vibration and exhaust. This can prevent the carbon stored in the pressure relief tank 101 from affecting its pressure reduction effect.

[0038] In one embodiment, such as Figure 2 As shown, the volume d of the pressure relief tank satisfies: d≥P1 / P2*V;

[0039] Where: P1 is the peak cylinder pressure under engine knocking conditions, P2 is the maximum pressure value of the pressure shock wave that the piston ring can withstand after being relieved by the pressure relief groove, and V is the clearance volume between the piston first ring land and the cylinder liner.

[0040] Figure 2 The direction indicated by the middle arrow is the flow direction of the pressure shock wave.

[0041] By calculating and limiting the minimum volume of the pressure relief groove 101, excessive weight reduction of the pressure relief groove 101 is avoided, which would affect the structural strength of the piston 100. This ensures the overall structural stability and application reliability of the piston 100 while achieving pressure wave buffering. Specifically, P1 and P2 are calculated based on the strength of the piston ring 103. This experimental calculation method involves changing the volume of the pressure relief groove 101, recording the P2 value for different volumes, and recording the degree of deformation of the piston ring 103 under knocking conditions. This yields the minimum volume of the pressure relief groove 101. The pressure relief groove 101 is then adaptively set based on this minimum volume to ensure the overall structural stability of the piston 100.

[0042] Preferably, the opening of the pressure relief groove 101 faces the cylinder liner 200, and an arc-shaped guide surface is provided at the opening on the upper wall of the pressure relief groove 101. The guide surface is not shown in the figure, but it is configured such that the upper wall of the groove at the opening of the pressure relief groove is an arc-shaped line, allowing gas to smoothly enter the pressure relief groove and further improving the pressure relief performance. When the gas flows downward through the pressure relief groove 101, the gas flow space increases, and the airflow diffuses into the pressure relief groove 101, thereby reducing the pressure of the high-temperature, high-pressure gas after passing through the pressure relief groove 101. The airflow entering the pressure relief groove 101 flows back from the bottom of the groove to the outside, impacting and canceling the airflow outside the groove, further weakening the airflow intensity. This reduces the impact force of the high-pressure gas when it reaches the piston ring 103, preventing the high-pressure shock wave airflow from impacting the piston ring 103 and causing it to deform and fail, thus ensuring the operational stability of the piston ring 103.

[0043] In one embodiment, such as Figure 2 As shown, the upper edge of the boss 105 forms the lower groove wall of the pressure relief groove 101, and the lower edge of the boss 105 forms the upper groove wall of the first piston ring groove 102.

[0044] Preferably, the piston first ring land 104 also includes a first wall surface located above the pressure relief groove 101, the bottom of the first wall surface forming the upper groove wall of the pressure relief groove 101, and the outer wall surface of the boss 105 protruding from the first wall surface and the outer wall surface of the first piston ring groove 102.

[0045] By setting the upper and lower edges of the boss 105 to form the lower wall of the pressure relief groove 101 and the upper wall of the first piston ring groove 102 respectively, the forming and processing difficulty of the pressure relief groove 101 is reduced, and the piston 100 is modified in a simple structure. Furthermore, the outer wall of the boss 105 protrudes above the first wall above the pressure relief groove 101 and protrudes above the outer wall of the first piston ring groove 102. That is, the lower wall of the pressure relief groove 101 protrudes above the upper wall of the pressure relief groove 101, and the upper wall of the first piston ring groove 102 protrudes above the upper wall of the pressure relief groove 101. Thus, when the high-pressure airflow descends, the boss 105 will have a certain blocking effect on the high-pressure airflow. Combined with the relatively inward-curving upper wall of the pressure relief groove 101, it is beneficial to introduce the high-pressure gas into the pressure relief groove 101 first, avoiding the gas from directly impacting the piston ring 103 located in the first piston ring groove 102, and further enhancing the protection effect of the piston ring 103.

[0046] In one embodiment, the piston 100 is provided with a recessed portion, which is arranged circumferentially along the piston 100 to form an annular pressure relief groove 101.

[0047] It is easy to understand that although the concave portion is not marked in the figure, the concave part of the piston 100 in the figure can be seen to be a concave portion, forming a pressure relief groove 101 around the circumference of the piston 100. By designing the piston 100 with a partial concave portion to form a concave portion, and setting the concave portion around the circumference of the piston 100, a pressure relief groove 101 is formed around the entire circumference of the piston 100, thereby achieving the pressure reduction effect of the pressure relief groove 101 on the gas in various angles and directions.

[0048] Furthermore, the depth of the concave portion is not less than half of the first piston ring groove 102. Given a fixed volume, if the depth of the concave portion is too large, the piston head will lose too much weight inward, which is detrimental to the structural strength stability of the piston 100; if the depth of the concave portion is too small, the anti-rolling effect on the high-pressure airflow will be poor, affecting the compression effect on the high-pressure shock wave.

[0049] It should be noted that there is no limitation on the shape of the pressure relief groove 101. The cross-section of the pressure relief groove 101 can be rectangular or U-shaped, or other shapes.

[0050] In one embodiment, such as Figure 1 As shown, the piston 100 is also provided with a second piston ring groove 107 located below the first piston ring groove 102, and the distance between the pressure relief groove 101 and the first piston ring groove 102 is greater than the distance between the first piston ring groove 102 and the second piston ring groove 107.

[0051] This method avoids the weight reduction area of ​​piston 100 being too concentrated, which could lead to structural instability. At the same time, it helps to extend the path of the gas rolled out of the pressure relief groove 101 to the piston ring 103, further improving the compression effect on high-pressure shock waves under detonation conditions.

[0052] This application also includes an engine, which includes a body and a cylinder, and the cylinder is provided with a piston 100 as in any of the above embodiments. The pressure relief groove 101 structure provided in the piston 100 weakens the impact force of the high temperature and high pressure gas of the knock impact, thereby protecting the piston ring 103 and preventing the piston ring 103 from plastic deformation due to the knock impact, thus helping to maintain the stability of the shape and function of the piston ring 103.

[0053] For any parts not mentioned in this application, existing technologies may be used or referenced.

[0054] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0055] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A piston for a methanol engine, characterized in that, The piston (100) includes a first piston ring land (104) near the cylinder liner (200). The piston (100) is provided with a first piston ring groove (102) for assembling a piston ring (103) and a pressure relief groove (101) provided on the first piston ring land (104). The pressure relief groove (101) is provided above the first piston ring groove (102). The first piston ring land (104) includes a boss (105) located between the pressure relief groove (101) and the first piston ring groove (102). A clearance gap (106) is provided between the boss (105) and the cylinder liner (200). The impact airflow passes through the pressure relief groove (101) and then flows through the clearance gap (106) to the first piston ring groove (102).

2. The piston for a methanol engine according to claim 1, characterized in that, The volume d of the pressure relief groove (101) conforms to the following condition: d≥P1 / P2*V; Wherein: P1 is the peak cylinder pressure during engine knocking, P2 is the maximum pressure value of the pressure shock wave that the piston ring (103) can withstand after being depressurized through the pressure relief groove (101), and V is the clearance volume between the piston first ring land (104) and the cylinder liner (200).

3. The piston for a methanol engine according to claim 2, characterized in that, The opening of the pressure relief groove (101) faces the cylinder liner (200), and the opening is provided with an arc-shaped guide surface located on the upper groove wall of the pressure relief groove (101).

4. The piston for a methanol engine according to claim 1, characterized in that, The upper edge of the boss (105) forms the lower groove wall of the pressure relief groove (101), and the lower edge of the boss (105) forms the upper groove wall of the first piston ring groove (102).

5. The piston for a methanol engine according to claim 4, characterized in that, The piston first ring land (104) also includes a first wall surface located above the pressure relief groove (101), the bottom of the first wall surface forming the upper groove wall of the pressure relief groove (101), and the outer wall surface of the boss (105) protruding from the first wall surface and the outer wall surface of the first piston ring groove (102).

6. The piston for a methanol engine according to claim 1, characterized in that, The piston (100) is provided with a concave portion, which is arranged circumferentially along the piston (100) to form an annular pressure relief groove (101).

7. The piston for a methanol engine according to claim 6, characterized in that, The depth of the concave portion is not less than one-half of the depth of the first piston ring groove (102).

8. The piston for a methanol engine according to claim 1, characterized in that, The cross-section of the pressure relief groove (101) is rectangular or U-shaped.

9. The piston for a methanol engine according to claim 1, characterized in that, The piston (100) is also provided with a second piston ring groove (107) located below the first piston ring groove (102), and the distance between the pressure relief groove (101) and the first piston ring groove (102) is greater than the distance between the first piston ring groove (102) and the second piston ring groove (107).

10. An engine comprising a block and cylinders, characterized in that, The cylinder is provided with a piston (100) as described in any one of claims 1-9.

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