Piston with optimized cooling effect

Abstract

The utility model discloses a piston of optimization cooling effect, including piston head and piston skirt, the top of piston head has combustion chamber, is equipped with central cooling oil cavity and outer cooling oil cavity in the piston head inside, central cooling oil cavity is located below the combustion chamber, and outer cooling oil cavity is located the outside of central cooling oil cavity, and the both are linked through oil hole channel, and piston skirt is equipped with inlet return oil pipe mounting hole, oil inlet hole and oil return hole, and oil return hole is located the upper center of piston skirt, and oil return hole is connected with central cooling oil cavity and piston inner chamber respectively, and oil inlet hole is connected with piston pinhole and outer cooling oil cavity respectively, and inlet return oil pipe mounting hole place fixed mounting has inlet return oil pipe, and the top of inlet return oil pipe is inserted into outer cooling oil cavity and is higher than the highest position of oil hole channel, and inlet return oil pipe is communicated with piston inner chamber. The above-mentioned one kind of piston of optimization cooling effect reduces the stagnation time of cooling oil, and the cooling effect is better, and can reduce the carbon deposit in cooling oil cavity.

Description

Technical Field

[0001] This utility model relates to the field of piston technology, specifically to a piston with optimized cooling effect. Background Technology

[0002] Diesel engine pistons operate under high temperature and high explosion pressure environments, resulting in extremely high temperatures for the piston head and piston rings, necessitating cooling measures. In existing technology, to reduce the operating temperature of the piston components, a cooling oil chamber is incorporated to provide sufficient cooling to the piston head. There are two types of piston head oil chamber structures:

[0003] One structure is a single-oil-chamber piston head structure. The single oil chamber is an annular cooling oil chamber located at the piston head, where cooling oil flows to cool the piston head. For example, Chinese patent document CN 217270510U discloses a piston with enhanced cooling effect. This design features a single cooling oil chamber structure, with the oil inlet pipe extending deep into the inner cooling oil chamber. The oil inlet pipe's nozzle is designed as an outwardly expanding conical opening. By designing the oil inlet pipe's nozzle as an outwardly expanding conical opening, the low-temperature cooling oil has a better dispersion effect when sprayed out, increasing the contact area with the inner wall of the central cooling oil chamber during injection, accelerating the heat absorption of the low-temperature cooling oil, and improving the cooling effect to a certain extent. However, it has the following disadvantages:

[0004] The height of the flared conical inlet on the oil inlet pipe is not a key factor affecting the oil filling rate, and its effect on adjusting the piston oil filling rate is very limited. The main function of the flared conical inlet is to disperse the oil injection and increase the injection area, but it cannot regulate the air pressure difference in the cooling oil chamber. The oil inlet pipe and the inner cooling oil chamber are cast as one piece, and the height of the oil inlet pipe is not adjustable, resulting in poor flexibility in optimizing the piston cooling effect, high cost, and if piston structure optimization or changes are involved, the old piston must be scrapped entirely.

[0005] Another structure is a dual-oil-chamber structure in the piston head, such as... Figure 1As shown, the dual oil chambers are an outer cooling oil chamber 5 (usually an annular cooling oil chamber) located at the piston head 1 and a central cooling oil chamber 6 located at the bottom of the combustion chamber 100. The two chambers are connected by an oil passage 7. After the cooling oil oscillates in the outer cooling oil chamber 5 and the central cooling oil chamber 6, it flows back from the central cooling oil chamber 6 to the crankcase via the return oil hole 8 to cool the piston head 1. During the cooling process, the amount of air entering the outer cooling oil chamber 5 is relatively small (part of the air comes from the oil inlet 3, and the other part comes from the backflow from the central cooling oil chamber 6). When the oil filling rate is high, the top area of ​​the outer cooling oil chamber 5 is easily surrounded by cooling oil into a closed space (not an ideal seal) when the piston moves upward. This can easily lead to a pressure difference between the outer cooling oil chamber 5 and the central cooling oil chamber 6. This pressure difference hinders the flow of cooling oil to the central cooling oil chamber 6 (similar to the "inverted cup experiment"), thus affecting the piston's cooling effect. This explains why, even though we knew the piston oil filling rate was too high, and we tried to reduce it by increasing the oil return hole, the piston cooling effect was still unsatisfactory after the test. Utility Model Content

[0006] In view of the above-mentioned defects in the prior art, the technical problem to be solved by this utility model is to provide a piston with optimized cooling effect, which can reduce the residence time of cooling oil, improve the cooling effect, and reduce carbon deposits in the cooling oil chamber.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A piston with optimized cooling includes a piston head and a piston skirt. A combustion chamber is located at the top of the piston head. The piston head also contains a central cooling oil chamber and an outer cooling oil chamber, with the central cooling oil chamber located below the combustion chamber.

[0009] The external cooling oil chamber is located outside the central cooling oil chamber, and the two are connected by an oil passage. The piston skirt is provided with an intake and return oil pipe mounting hole, an oil inlet, and an oil return hole. The oil return hole is located at the upper center of the piston skirt and is connected to both the central cooling oil chamber and the piston inner cavity. The oil inlet is connected to both the piston pin hole and the external cooling oil chamber. An intake and return oil pipe is fixedly installed at the intake and return oil pipe mounting hole. The top end of the intake and return oil pipe extends into the external cooling oil chamber and is higher than the highest point of the oil passage. The intake and return oil pipe communicates with the piston inner cavity.

[0010] Preferably, the distance from the top of the intake oil return pipe to the highest point of the oil passage is L, where 3mm ≤ L ≤ 5mm.

[0011] Preferably, the total area of ​​the intake and return oil pipe diameter plus the total area of ​​the return oil hole diameter is 2 to 4 times the total area of ​​the intake oil hole diameter; that is:

[0012]

[0013] in:

[0014] n1 is the number of oil return holes of the piston;

[0015] n2 is the number of intake return oil pipes;

[0016] n3 is the number of oil inlet holes of the piston;

[0017] D1 is the diameter of the piston's oil return hole;

[0018] D2 is the diameter of the intake return oil pipe hole;

[0019] d is the diameter of the piston's oil inlet hole.

[0020] Preferably, the intake oil return pipe mounting hole is threadedly connected to the intake oil return pipe, and the threaded connection between the intake oil return pipe mounting hole and the intake oil return pipe is coated with adhesive.

[0021] Preferably, the external cooling oil cavity is an annular oil cavity.

[0022] Preferably, the combustion chamber is a dumbbell-shaped grooved oil cavity.

[0023] Preferably, the piston head and piston skirt are fixedly connected by bolts.

[0024] Preferably, the piston is installed in the inner cavity of the cylinder liner and can reciprocate up and down in the inner cavity of the cylinder liner. A water jacket shell is fixed outside the cylinder liner, and a cooling water jacket is between the water jacket shell and the cylinder liner. An annular groove is formed on the piston head. When the piston runs to the top dead center, the annular groove is located within the range corresponding to the cooling water jacket.

[0025] Preferably, the piston skirt is provided with an annular oil groove and an auxiliary lubricating oil hole. The auxiliary lubricating oil hole includes a large-diameter hole section, a tapered transition hole section and a small-diameter hole section connected in sequence. The outer end of the large-diameter hole section is connected to the annular oil groove, and the inner end of the small-diameter hole section is connected to the oil inlet hole.

[0026] Preferably, the piston skirt is provided with an oblique oil return hole, the piston head is provided with an oil scraper ring groove and a connecting oil hole, the oil scraper ring groove is located below the first ring groove, the oblique oil return hole is located below the oil scraper ring groove, the connecting oil hole connects the oil scraper ring groove and the oblique oil return hole, and the bottom end of the oblique oil return hole connects to the piston cavity.

[0027] The beneficial effects of this utility model after adopting the above technical solution are:

[0028] This invention features an internal intake and return oil pipe for optimized cooling, offering the following advantages: The top of the intake and return oil pipe extends into the external cooling oil chamber and is higher than the highest point of the oil passage. The pipe communicates with the piston's internal cavity. During piston movement, air can enter the external cooling oil chamber through the intake and return oil pipe, maintaining pressure balance between the central and external cooling oil chambers. This facilitates the flow of cooling oil from the external cooling oil chamber to the central cooling oil chamber, enhancing the piston's cooling effect. The intake and return oil pipe also provides some oil return (according to relevant research, the return oil volume can account for 10% to 25% of the total piston oil output). The height of the intake and return oil pipe allows for adjustment of the piston's oil filling rate, preventing insufficient or excessive cooling.

[0029] While keeping the number and diameter of the oil inlet holes unchanged, adding an intake and return oil pipe in the external cooling oil chamber can reduce the oil filling rate and accelerate the rapid flow of cooling oil out of the piston. Part of the cooling oil flows away through the intake and return oil pipe, while the rest flows rapidly into the central cooling oil chamber and flows away through the return oil hole, reducing the residence time of the cooling oil, resulting in better cooling effect and less carbon buildup in the cooling oil chamber.

[0030] In summary, the piston of this invention with optimized cooling effect not only reduces the residence time of cooling oil and improves the cooling effect, but also reduces carbon deposits in the cooling oil chamber. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of a dual-oil-chamber piston in the prior art;

[0032] Figure 2 This is a partial structural schematic diagram of a piston for optimizing cooling effect according to this utility model;

[0033] Figure 3 yes Figure 2 Enlarged structural diagram at point I;

[0034] Figure 4 This is a schematic diagram of the structure of a piston for optimizing cooling effect according to this utility model;

[0035] In the diagram: 1. Piston head; 2. Piston skirt; 20. Oil scraper ring groove; 21. Connecting oil hole; 3. Oil inlet hole; 4. Intake oil return pipe mounting hole; 5. External cooling oil chamber; 6. Central cooling oil chamber; 7. Oil passage; 8. Oil return hole; 9. Intake oil return pipe; 100. Combustion chamber; 11. Cylinder liner; 12. Water jacket shell; 13. Cooling water jacket; 14. Ring groove; 15. Angled oil return hole; 16. Auxiliary lubricating oil hole; 161. Large diameter bore section; 162. Tapered transition bore section; 163. Small diameter bore section; 17. Annular oil groove. Detailed Implementation

[0036] The technical solution of this utility model will be described in detail below with reference to the accompanying drawings and specific embodiments to further understand the purpose, solution and effect of this utility model, but it is not intended to limit the scope of protection of the appended claims of this utility model.

[0037] In the description of this utility model, it should be noted that the terms "front", "rear", "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model 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. Therefore, they should not be construed as limitations on this utility model.

[0038] Furthermore, although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used in this document do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0039] like Figure 2 and Figure 3 The piston shown includes a piston head 1 and a piston skirt 2. A combustion chamber is located at the top of the piston head 1. The piston head 1 has a central cooling oil chamber 6 and an outer cooling oil chamber 5 inside. The central cooling oil chamber 6 is located below the combustion chamber 100.

[0040] The external cooling oil chamber 5 is located outside the central cooling oil chamber 6. The external cooling oil chamber 5 and the central cooling oil chamber 6 are connected through the oil passage 7. The piston skirt 2 is provided with an intake oil return pipe mounting hole 4, an oil inlet 3, and an oil return hole 8. The oil return hole 8 is located at the upper center of the piston skirt. The oil return hole 8 is connected to the central cooling oil chamber 6 and the piston cavity, respectively. The inlet end of the oil inlet 3 is connected to the piston pin hole, and the outlet end of the oil inlet 3 is connected to the external cooling oil chamber 5. An intake oil return pipe 9 is fixedly installed at the intake oil return pipe mounting hole 4. The top end of the intake oil return pipe 9 extends into the external cooling oil chamber 5 and is higher than the highest point of the oil passage 7. The intake oil return pipe 9 is connected to the piston cavity.

[0041] The aforementioned intake and return oil pipe 9 connects the external cooling oil chamber 5 and the piston inner cavity, and can adjust the air pressure difference between the central cooling oil chamber 6 and the external cooling oil chamber 5, thus preventing the air pressure difference from hindering the flow of cooling oil to the central cooling oil chamber 6.

[0042] The piston oil filling rate can be effectively adjusted by adjusting the height and inner diameter of the intake oil return pipe 9.

[0043] Let L be the distance from the top of the intake oil return pipe 9 to the highest point of the oil passage 7, where 3mm ≤ L ≤ 5mm.

[0044] The intake oil return pipe 9 has the function of accelerating the flow of cooling oil, resulting in better piston cooling and preventing carbon deposits from forming on the inner walls of each cooling oil chamber.

[0045] The total area of ​​the intake and return oil pipe 9 plus the diameter of the return oil hole 8 is 2 to 4 times the total area of ​​the intake hole 3; that is:

[0046]

[0047] in:

[0048] n1 is the number of oil return holes of the piston;

[0049] n2 is the number of intake return oil pipes;

[0050] n3 is the number of oil inlet holes of the piston;

[0051] D1 is the diameter of the piston's oil return hole;

[0052] D2 is the diameter of the intake return oil pipe hole;

[0053] d is the diameter of the piston's oil inlet hole.

[0054] The intake return oil pipe mounting hole 4 is threadedly connected to the intake return oil pipe 9. The intake return oil pipe mounting hole 4 has an internal thread, and the intake return oil pipe 9 has an external thread that matches the internal thread. Adhesive is applied to the threaded connection between the intake return oil pipe mounting hole 4 and the intake return oil pipe 9. This threaded connection is a replaceable design; during maintenance, replacement, or structural optimization, only the intake return oil pipe 9 needs to be replaced, simplifying operation and reducing the cost of iterative structural optimization.

[0055] The oil passage 7 is set as a horizontal circular passage, the external cooling oil chamber 5 is an annular oil chamber, and the combustion chamber 100 is a dumbbell-shaped grooved oil chamber.

[0056] The intake oil return pipe mounting hole 4 is set perpendicularly to the oil passage 7.

[0057] The piston head 1 and the piston skirt 2 are fixedly connected by bolts, preferably by four bolts.

[0058] The piston of this invention, with its optimized cooling effect, features an intake and return oil pipe 9, which offers the following advantages: The top of the intake and return oil pipe 9 extends into the outer cooling oil chamber 5 and is higher than the highest point of the oil passage 7. The intake and return oil pipe 9 communicates with the piston's inner cavity. During piston movement, air can enter the outer cooling oil chamber 5 through the intake and return oil pipe 9, maintaining pressure balance between the central cooling oil chamber 6 and the outer cooling oil chamber 5. This facilitates the flow of cooling oil from the outer cooling oil chamber 5 to the central cooling oil chamber 6, increasing the piston's cooling effect. The intake and return oil pipe 9 also has a certain oil return function (according to relevant research, the oil return volume of the intake and return oil pipe 9 can account for 10% to 25% of the total oil output of the piston). The height of the intake and return oil pipe 9 allows for adjustment of the piston's oil filling rate, preventing insufficient or excessive cooling of the piston.

[0059] While keeping the number and diameter of the oil inlet holes 3 unchanged, an intake return oil pipe 9 is added to the outer cooling oil chamber 5. This can reduce the oil filling rate and accelerate the rapid flow of cooling oil out of the piston. Part of the cooling oil flows away through the intake return oil pipe 9, and part of the cooling oil flows rapidly into the central cooling oil chamber 6 and flows away through the return oil hole 8. This reduces the residence time of the cooling oil, resulting in better cooling effect and less carbon buildup in the cooling oil chamber.

[0060] like Figure 4 As shown, the piston is installed in the inner cavity of the cylinder liner 11, and can reciprocate up and down within the inner cavity of the cylinder liner 11. A water jacket shell 12 is fixed outside the cylinder liner 11, forming a cooling water jacket 13 between the water jacket shell 12 and the cylinder liner 11. An annular groove 14 is formed on the piston head 1. When the piston reaches top dead center, the annular groove 14 is located within the corresponding cooling water jacket 13. When the piston reciprocates up and down within the inner cavity of the cylinder liner 11, the piston rings rub against the inner wall of the cylinder liner 11, causing the temperature to rise. The temperature of the piston annular groove 14 directly affects the working performance of the piston rings. Therefore, controlling the temperature of the piston annular groove 14 must be considered in the design. When the piston reaches top dead center, the annular groove 14 is located within the corresponding cooling water jacket 13, which contains cooling liquid. This structure ensures optimal cooling at the piston annular groove 14.

[0061] The piston skirt 2 is provided with an annular oil groove 17 and an auxiliary lubricating oil hole 16. The auxiliary lubricating oil hole 16 includes a large-diameter hole section 161, a tapered transition hole section 162, and a small-diameter hole section 163 connected in sequence. The outer end of the large-diameter hole section 161 is connected to the annular oil groove 17, and the inner end of the small-diameter hole section 163 is connected to the oil inlet hole 3. Preferably, the diameter of the small-diameter hole section 163 is set to 1.5 mm. During the piston's upward movement, lubricating oil enters the annular oil groove 17 of the piston skirt 2 through the auxiliary lubricating oil hole 16, so that the piston has an appropriate amount of lubricating oil distributed on the surface of the cylinder liner 11. This prevents insufficient oil during the piston's upward movement, which could lead to severe frictional heat generation due to poor lubrication, causing the piston to melt and scorch due to high frictional temperature.

[0062] The piston skirt 2 is provided with an oblique oil return hole 15, and the piston head 1 is provided with an oil scraper ring groove 20 and a connecting oil hole 21. The oil scraper ring groove 20 is located below the first ring groove 14, and the oblique oil return hole 15 is located below the oil scraper ring groove 20. The connecting oil hole 21 connects the oil scraper ring groove 20 and the oblique oil return hole 15. The bottom end of the oblique oil return hole 15 connects to the piston cavity. During the piston's downward movement, an oil scraper ring is fixed in the oil scraper ring groove 20. A large amount of lubricating oil scraped off by the oil scraper ring flows back into the piston cavity through the oblique oil return hole 15 and back to the oil pan. This prevents a large amount of lubricating oil scraped off during the piston's downward movement from not being able to be cleared in time, causing the lubricating oil to be pumped back to the first ring groove 14, resulting in severe carbon buildup in the first ring groove 14, poor gas flow, and the piston heat not being effectively transferred to the cylinder liner through the first ring groove 14, thus weakening the piston's cooling effect.

[0063] The piston skirt is designed with auxiliary lubrication holes 16 and oblique return oil holes 15, which makes the upward oil distribution and downward oil scraping of the piston more scientific and reasonable, preventing dry friction and cylinder scoring caused by unreasonable oil distribution, and preventing the lubricating oil from being pumped back to the first ring groove due to poor oil scraping, resulting in carbon deposits and affecting the piston cooling effect.

[0064] This utility model is not limited to the above embodiments. All improvements made based on the concept, principle, structure and method of this utility model are within the protection scope of this utility model.

Claims

1. A piston with optimized cooling effect, comprising a piston head (1) and a piston skirt (2), wherein a combustion chamber (100) is provided at the top of the piston head (1), and a central cooling oil chamber (6) and an outer cooling oil chamber (5) are provided inside the piston head (1), wherein the central cooling oil chamber (6) is located below the combustion chamber (100), characterized in that: The external cooling oil chamber (5) is located outside the central cooling oil chamber (6), and the two are connected by an oil passage (7). The piston skirt (2) is provided with an intake oil return pipe mounting hole (4), an oil inlet (3) and an oil return hole (8). The oil return hole (8) is located at the upper center of the piston skirt. The oil return hole (8) is connected to the central cooling oil chamber (6) and the piston cavity respectively. The oil inlet (3) is connected to the piston pin hole and the external cooling oil chamber (5) respectively. An intake oil return pipe (9) is fixedly installed at the intake oil return pipe mounting hole (4). The top end of the intake oil return pipe (9) extends into the external cooling oil chamber (5) and is higher than the highest position of the oil passage (7). The intake oil return pipe (9) is connected to the piston cavity.

2. The piston with optimized cooling effect as described in claim 1, characterized in that: [the piston is provided with...] The distance from the top of the intake oil return pipe (9) to the highest point of the oil passage (7) is L, 3mm≤L≤5mm.

3. The piston with optimized cooling effect as described in claim 2, characterized in that: The total area of ​​the intake and return oil pipe (9) plus the total area of ​​the return oil hole (8) is 2 to 4 times the total area of ​​the intake hole (3); that is: in: n1 is the number of oil return holes of the piston; n2 is the number of intake return oil pipes; n3 is the number of oil inlet holes on the piston; D1 is the diameter of the piston's oil return hole; D2 is the diameter of the intake return oil pipe hole; d is the diameter of the piston's oil inlet hole.

4. The piston with optimized cooling effect as described in claim 3, characterized in that: The intake oil return pipe mounting hole (4) is threadedly connected to the intake oil return pipe (9), and the threaded connection between the intake oil return pipe mounting hole (4) and the intake oil return pipe (9) is coated with adhesive.

5. The piston with optimized cooling effect as described in claim 4, characterized in that: The external cooling oil chamber (5) is an annular oil chamber.

6. The piston with optimized cooling effect as described in claim 5, characterized in that: The combustion chamber (100) is a dumbbell-shaped grooved oil cavity.

7. The piston with optimized cooling effect as described in claim 6, characterized in that: The piston head (1) and piston skirt (2) are fixedly connected by bolts.

8. The piston with optimized cooling effect as described in claim 7, characterized in that: The piston is installed in the inner cavity of the cylinder liner (11) and can reciprocate up and down in the inner cavity of the cylinder liner (11). A water jacket shell (12) is fixed outside the cylinder liner (11). A cooling water jacket (13) is between the water jacket shell (12) and the cylinder liner (11). An annular groove (14) is opened on the piston head (1). When the piston runs to the top dead center, the annular groove (14) is located within the range of the corresponding cooling water jacket (13).

9. A piston with optimized cooling effect as described in claim 8, characterized in that: The piston skirt (2) is provided with an annular oil groove (17) and an auxiliary lubricating oil hole (16). The auxiliary lubricating oil hole (16) includes a large-diameter hole section (161), a tapered transition hole section (162), and a small-diameter hole section (163) connected in sequence. The outer end of the large-diameter hole section (161) is connected to the annular oil groove (17), and the inner end of the small-diameter hole section (163) is connected to the oil inlet hole (3).

10. A piston with optimized cooling effect as described in claim 9, characterized in that: The piston skirt (2) is provided with an oblique oil return hole (15), and the piston head (1) is provided with an oil scraper ring groove (20) and a connecting oil hole (21). The oil scraper ring groove (20) is located below the first ring groove (14), and the oblique oil return hole (15) is located below the oil scraper ring groove (20). The connecting oil hole (21) connects the oil scraper ring groove (20) and the oblique oil return hole (15). The bottom end of the oblique oil return hole (15) is connected to the piston cavity.

Images