Piston, internal combustion engine and vehicle

Abstract

The piston has a piston head, a piston skirt, and an oil flow path. The piston skirt is provided on the bottom side with respect to the piston head, and a pin hole is formed in the piston skirt in an extension direction intersecting the vertical direction. The oil flow path extends through the piston head and the piston skirt, and has an opening that opens toward the bottom at the piston skirt. The size of the opening in the extension direction of the pin hole is larger than the size of the opening in the width direction intersecting both the vertical direction and the extension direction of the pin hole.

Description

Technical Field

[0001] This invention relates to pistons, internal combustion engines, and vehicles. Background Technology

[0002] In an internal combustion engine used in vehicles, the reciprocating motion of the piston within the cylinder is converted into the rotational motion of the crankshaft. A pin hole is formed in the piston skirt, through which a piston pin is inserted. In an internal combustion engine, the piston is connected to the connecting rod via the piston pin.

[0003] Furthermore, in internal combustion engines, fuel injectors are sometimes installed in the cylinders to spray engine oil towards the piston. In such internal combustion engines, the piston is cooled by the oil from the fuel injectors. Additionally, in internal combustion engines with fuel injectors, an oil flow path is formed inside the piston, allowing the oil injected from the fuel injectors to flow into the oil flow path. In pistons with formed oil flow paths, the inflow portion of the oil from the fuel injectors is formed as an opening towards the bottom side in the piston skirt.

[0004] In the piston of an internal combustion engine, from the viewpoint of reducing frictional losses during reciprocating motion, efforts are made to reduce the rigidity of the piston skirt relative to the load. For example, in structures where the oil flow path is formed inside the piston, efforts are made to reduce the rigidity of the piston skirt near the opening of the oil flow path. Summary of the Invention

[0005] The problem to be solved by the present invention is to provide a piston that can reduce the rigidity of the piston skirt in a structure forming an oil flow path, and an internal combustion engine and vehicle having the piston.

[0006] In one embodiment of the invention, the piston has a piston head, a piston skirt, and an oil passage. The piston skirt is disposed on the bottom side relative to the piston head, and a pin hole is formed in the piston skirt along an extending direction intersecting the vertical direction. The oil passage extends through the piston head and the piston skirt, and has an opening at the piston skirt that opens towards the bottom side. The size of the opening along the extending direction of the pin hole is larger than the size of the opening along the width direction intersecting both the vertical direction and the extending direction of the pin hole.

[0007] According to the present invention, a piston capable of reducing the rigidity of the piston skirt in a structure forming an oil flow path, and an internal combustion engine and vehicle having the piston can be provided. Attached Figure Description

[0008] Figure 1 This is a cross-sectional view that schematically illustrates an example of a piston and the structure in the vicinity of an internal combustion engine according to an embodiment.

[0009] Figure 2 Viewed from the bottom side Figure 1 A schematic diagram of an example piston.

[0010] Figure 3 Therefore with Figure 1 Different cross-sections are roughly represented Figure 1 A cross-sectional view of an example piston.

[0011] Figure 4 Is Figure 1 A schematic diagram of the opening of the inlet section forming the oil flow path and the surrounding structure in an example piston, viewed from the bottom side.

[0012] Figure 5 This is a schematic diagram of the opening of the inlet portion forming the oil flow path and its surrounding structure, viewed from the bottom side in a piston involved in a certain variation.

[0013] Figure 6 In the context of Figure 5 A schematic diagram of the opening of the inlet portion forming the oil flow path and its surrounding structure in a piston of a different variant, viewed from the bottom side.

[0014] Figure 7 It is a general representation of... Figure 5 and Figure 6 A cross-sectional view of the piston involved in a different variation.

[0015] Figure 8 This is a schematic diagram illustrating an example of the structure of a vehicle equipped with an internal combustion engine according to the embodiment. Detailed Implementation

[0016] Hereinafter, the embodiments will be described with reference to the accompanying drawings.

[0017] In an internal combustion engine mounted in a vehicle or similar vehicle, there is one or more pistons and the same number of cylinders. Each piston reciprocates vertically within a corresponding internal cavity of one cylinder. For example, in a four-cylinder internal combustion engine, there are four pistons and four cylinders, each reciprocating within a corresponding internal cavity of one of the four cylinders. In the internal combustion engine, each piston is connected to the crankshaft via a connecting rod. The crankshaft rotates due to the reciprocating motion of this piston. That is, the reciprocating motion of the piston is converted into the rotational motion of the crankshaft. In this embodiment, the configuration of having one or more pistons in the internal combustion engine is as described below. Furthermore, the configuration described below is applicable to both diesel and gasoline engines.

[0018] Figure 1 This is a cross-sectional view schematically illustrating an example of a piston 3 and its surrounding structure in an internal combustion engine 1 according to an embodiment. For example... Figure 1 As shown, the internal combustion engine 1 has a cylinder 2 and a piston 3. In the internal combustion engine 1 and the piston 3, a vertical direction (indicated by arrows Y1 and Y2) and a forward / backward direction (indicated by arrow Z) intersecting the vertical direction (orthogonal or approximately orthogonal) are defined. Figure 1 The diagram shows cross-sections along both the vertical and longitudinal directions. In the internal combustion engine 1 and piston 3, the side in the vertical direction is called the top side (arrow Y1 side), and the side in the vertical direction opposite to the top side is called the bottom side (arrow Y2 side).

[0019] Cylinder 2 is cylindrical with its central axis running vertically. A piston 3 is disposed within the internal cavity of cylinder 2. Piston 3 reciprocates vertically within the internal cavity of cylinder 2. Therefore, the vertical direction is also referred to as the reciprocating direction of piston 3 and the moving direction of piston 3. In internal combustion engine 1, an intake port and an exhaust port (neither shown) are disposed on the top side relative to piston 3. Furthermore, a combustion chamber is formed within the internal cavity of cylinder 2 by the spaces between the intake port and the exhaust port and piston 3. Additionally, in internal combustion engine 1, a crankshaft (not shown) is disposed on the bottom side relative to piston 3.

[0020] In an internal combustion engine 1, for example, the four processes of intake, compression, expansion, and exhaust are repeatedly performed in a cycle. In the intake process of the internal combustion engine 1, gas is introduced into the combustion chamber inside the cylinder 2 through the intake port, and the piston 3 moves to the bottom dead center. Then, in the compression process, the piston 3 moves from the bottom dead center to the top dead center. The top dead center reached by the piston 3 during the compression process is also called the compression top dead center. In the cycle of a diesel engine, during the compression process, the combustion chamber becomes very hot. At any point in time, around the compression top dead center, diesel fuel is injected into the combustion chamber, igniting the gas in the combustion chamber, thus causing combustion. In the cycle of a gasoline engine, during the intake process, gasoline and gas are introduced into the combustion chamber together. At any point in time, around the compression top dead center, the gas in the combustion chamber is ignited by a spark plug or the like, thus causing combustion. Then, in the expansion process, the piston 3 moves from the compression top dead center to the bottom dead center. Then, during the exhaust process, piston 3 moves from bottom dead center to top dead center, and gas is discharged from the exhaust port into the internal cavity of cylinder 2. As described above, the internal combustion engine 1 cycles, so that during one cycle, piston 3 reciprocates twice between top dead center and bottom dead center, performing a four-stroke movement.

[0021] The piston 3 has a piston head 5 and a piston skirt 6. The piston skirt 6 is disposed on the bottom side relative to the piston head 5. Figure 1In one example, the piston skirt 6 connects to the piston head 5 from the bottom side. Furthermore, in the piston 3, the piston head 5 forms the top end face (upper end face) 7, and the piston skirt 6 forms the bottom end face (lower end face) 8. Additionally, in... Figure 1 In one example, the piston head 5 is formed as a column with an outer periphery 11, and the piston skirt 6 is formed as a cylinder with an outer periphery 12 and an inner periphery 13. During the reciprocating motion of the piston 3, the outer periphery 11 of the piston head 5 and the outer periphery 12 of the piston skirt 6 each slide vertically relative to the inner periphery of the cylinder 2. Figure 1 In one example of the piston 3, a space 15 is formed on the inner circumferential side of the piston skirt 6, and the space 15 is covered by the piston skirt 6 throughout the entire circumference of the piston 3. Furthermore, the space 15 opens towards the bottom side, and the lower surface 16 of the piston head 5 is adjacent to the space 15 from the top side.

[0022] An annular groove 17, recessed towards the inner circumference, is formed on the outer periphery 11 of the piston head 5. Figure 1 In one example, three annular grooves 17 are formed. Each annular groove 17 extends circumferentially along the piston 3, covering the entire circumference. Alternatively, in a structure forming multiple annular grooves 17, the multiple annular grooves 17 are arranged separately from each other in the vertical direction. Piston rings (not shown) are installed in each annular groove 17. Furthermore, the number of annular grooves 17 formed in the piston head 5 is adjusted to an appropriate number corresponding to the internal combustion engine 1 using the piston 3.

[0023] Figure 2 Viewed from the bottom side Figure 1 A schematic diagram of a piston with three pistons as an example. Furthermore, in Figure 1 In, it is shown Figure 2 Section S1. (e.g.) Figure 1 and Figure 2 As shown, the piston skirt 6 has a pair of pin seats 21. The pair of pin seats 21 are arranged separately from each other in the front-rear direction, facing each other across a space 15. Furthermore, the pair of pin seats 21 are arranged separately from each other by approximately half a circumference in the circumferential direction of the piston 3. Each of the pair of pin seats 21 forms a pin hole 22, which extends through the piston skirt 6 from the outer peripheral portion 12 to the inner peripheral portion 13. In each pin seat 21, the pin hole 22 extends in the front-rear direction. Furthermore, the central axis C of each pin hole 22 is in the front-rear direction. Therefore, the front-rear direction is also referred to as the extension direction of the pin hole 22, the penetration direction of the pin hole 22, and the axial direction of the pin hole 22.

[0024] In the internal combustion engine 1, piston pins (not shown) are inserted into each pin hole 22, and piston pins are installed in the pin holes 22 of the piston skirt 6. Furthermore, the piston 3 is connected to the connecting rod (not shown) via the piston pin. Thus, the piston 3 is connected to the crankshaft via the piston pin and the connecting rod. In addition, during the cyclic operation of the internal combustion engine 1, the piston 3 rotates around the piston pin in parallel with the aforementioned reciprocating motion. This rotation of the piston around the piston pin is also called a swaying motion. During the swaying motion, the piston's rotation axis is coaxial or approximately coaxial with the central axis of the piston pin, and coaxial or approximately coaxial with the central axis C of each pin hole 22.

[0025] Furthermore, in piston 3, a width direction (indicated by arrow X) is defined that intersects (orthogonally or approximately orthogonally) both the vertical direction (reciprocating motion direction) and the front-back direction (extension direction of pin hole 22). In internal combustion engine 1, piston 3, through the aforementioned tilting motion, changes from a neutral state along the vertical direction (central axis of cylinder 2) to an inclined state relative to the vertical direction. In the neutral state, one side of piston 3's width direction coincides with or approximately coincides with the thrust side, and the side of piston 3's width direction opposite to the thrust side coincides with or approximately coincides with the anti-thrust side. Therefore, the width direction of piston 3 is also called the thrust-anti-thrust direction. Furthermore, in Figure 1 The image shows a cross-section that is orthogonal or approximately orthogonal to the width direction of piston 3.

[0026] In the internal combustion engine 1, the piston 3 tilts relative to the vertical direction due to the swaying motion, thereby generating side pressure between the piston 3 and the cylinder 2. During and around the compression top dead center, including the transition from the compression to the expansion phase, the portion closer to the top side than the pin hole 22 rotates towards the thrust side relative to its neutral position. Furthermore, immediately following the compression top dead center, the maximum side pressure is generated on the thrust side relative to the central axis of the cylinder 2.

[0027] like Figure 1 and Figure 2 As shown, in piston 3, oil flow path 23 extends through piston head 5 and piston skirt 6. In internal combustion engine 1, oil injector 25 is mounted in cylinder 2. Injector 25 has injection port 27 from which oil is injected. Injector 25 is disposed on the bottom side relative to piston 3 within an internal cavity of cylinder 2. Through the aforementioned reciprocating motion, piston 3 moves towards bottom dead center, thereby approaching injector 25. Conversely, by moving piston 3 towards top dead center, piston 3 moves away from injector 25. Figure 1 The image shows the state where piston 3 is at or near bottom dead center.

[0028] The fuel injector 25 injects oil into the cylinder 2 through an internal orifice, spraying oil towards the top side and towards the reciprocating piston 3. The oil from the fuel injector 25 cools the piston 3, improving its lubrication. The amount of oil injected from the fuel injector 25 varies accordingly with the pressure in the cylinder 2's internal orifice. For example, during the period immediately following top dead center of compression when the combustion chamber is burning, the amount of oil injected from the fuel injector 25 increases compared to other periods. When the piston 3 is at or near bottom dead center, i.e., at the precise timing of the piston 3 approaching the fuel injector 25, the injected oil flows into the oil flow path 23 of the piston 3. Furthermore, when the piston 3 is positioned a certain distance away from the fuel injector 25 towards the top side, the oil injected from the fuel injector 25 does not flow into the oil flow path 23.

[0029] Figure 3 Therefore with Figure 1 Different cross-sections are roughly represented Figure 1 A cross-sectional view of piston 3 as an example. Figure 3 In the diagram, a direction orthogonal or approximately orthogonal to the width direction of piston 3 is shown, and relative to... Figure 1 The cross-section is offset in the width direction of piston 3. That is, in Figure 3 In, it is shown Figure 2 Section S2. (e.g.) Figure 1 and Figure 3 As shown, the oil flow path 23 has a cooling chamber 26 formed inside the piston head 5. In the piston head 5, the cooling chamber 26 is formed in the vertical direction between the end face 7 on the top side of the piston 3 and the lower surface 16 of the piston head 5. Furthermore, the cooling chamber 26 is formed on the inner circumferential side of the piston 3 relative to the annular groove 17. Figure 1 and Figure 3 In one example, the cooling chamber 26 extends circumferentially along the piston 3. Furthermore, the cooling chamber 26 is formed over the entire circumference, extending circumferentially in a ring shape.

[0030] In addition, such as Figures 1 to 3 As shown, the oil flow path 23 has outward openings 31 and 35. Each opening 31 and 35 opens towards the bottom at the piston skirt 6. Figures 1 to 3 In one example, openings 31 and 35 are each located on the top side relative to the bottom end face 8 of the piston 3, opening toward the space 15. Additionally, the oil flow path 23 has connecting passages 32 and 36. Connecting passage 32 connects opening 31 to the cooling chamber 26, extending from opening 31 toward the cooling chamber 26 and toward the top side. Similarly, connecting passage 36 connects opening 35 to the cooling chamber 26, extending from opening 35 toward the cooling chamber 26 and toward the top side. Furthermore, in... Figure 1The image shows a cross-section passing through the opening 31 and the connecting passage 32. Figure 3 The image shows a cross-section passing through the opening 35 and the connecting path 36.

[0031] exist Figures 1 to 3 In one example, the opening 35 and the connecting passage 36 are located separately from the opening 31 and the connecting passage 32 in both the extending direction of the pin hole 22 and the width direction of the piston 3. Furthermore, the opening 35 and the connecting passage 36 are arranged separately from the opening 31 and the connecting passage 32 by half a circumference or approximately half a circumference in the circumferential direction of the piston 3. However, in one example, the opening 35 and the connecting passage 36 are located separately from the opening 31 and the connecting passage 32 in the extending direction of the pin hole 22, but this could also be a structure where they are not offset or substantially not offset in the width direction of the piston 3. Additionally, in one example, the opening 35 and the connecting passage 36 are located separately from the opening 31 and the connecting passage 32 in the width direction of the piston 3, but this could also be a structure where they are not offset or substantially not offset in the extending direction of the pin hole 22.

[0032] like Figure 1 As shown, with the piston 3 at or near bottom dead center, the fuel injector 25 is inserted into the space 15 from the bottom side, and the injection port 27 faces the opening 31 from the bottom side within the space 15. Furthermore, with the piston 3 at or near bottom dead center, the fuel injector 25 injects engine oil toward the opening 31, and the oil from the fuel injector 25 flows into the oil flow path 23 through the opening 31. Therefore, the opening 31 forms an inflow portion for the oil from the fuel injector 25 to flow into the oil flow path 23. The oil flowing in from the opening 31 flows to the cooling chamber 26 through the connecting passage 32.

[0033] Furthermore, when engine oil is flowing into the oil flow path 23 from the opening 31, the engine oil flowing into the cooling chamber 26 flows to the opening 35 through the connecting passage 36. Engine oil then flows out of the oil flow path 23 through the opening 35. Therefore, the opening 35 forms an outlet for engine oil to flow out of the oil flow path 23. As described above, engine oil flows in the oil flow path 23; therefore, the opening 31 is also called an inlet, and the connecting passage 32 is also called an inflow-side connecting passage. Furthermore, the opening 35 is also called an outlet, and the connecting passage 36 is also called an outflow-side connecting passage. Additionally, when engine oil is not flowing into the oil flow path 23 from the opening 31, engine oil can flow from the cooling chamber 26 to the opening 31 through the connecting passage 32. In this case, engine oil flows out of the oil flow path 23 through the opening 31.

[0034] Figure 4 Is Figure 1 A schematic diagram of the opening 31 of the inlet portion forming the oil flow path 23 and its surrounding structure, viewed from the bottom side in an example piston 3. Figure 4 In the middle, shown in magnification Figure 2 The opening 31 and its surrounding portion. Figure 2 and Figure 4 In one example, the opening (inlet) 31 is formed as an ellipse, with its major axis along the extension direction of the pin hole 22 and its minor axis along the width direction of the piston 3. Therefore, the size L1 of the opening 31 along the extension direction of the pin hole 22 is larger than the size L2 of the opening 31 along the width direction of the piston 3.

[0035] Furthermore, the opening edge surrounding the opening 31 has portions 41 and 42 that connect with the opening 31 in the width direction, and portions 43 and 44 that connect with the opening 31 in the extending direction (front-rear direction) of the pin hole 22. Portion 41 connects with the opening 31 from one side in the width direction, and portion 42 connects with the opening 31 from the side opposite to portion 41 in the width direction. Furthermore, portions 41 and 42 are opposite to each other across the opening 31. Additionally, portion 43 connects with the opening 31 from one side in the front-rear direction, and portion 44 connects with the opening 31 from the side opposite to portion 43 in the front-rear direction. Furthermore, portions 43 and 44 are opposite to each other across the opening 31. Figure 2 and Figure 4 In one example, the opening 31 is formed into the aforementioned ellipse shape; therefore, the portions 41 to 44 are each formed into a curved shape, which is an arc protruding away from the central axis A1 of the opening 31. Furthermore, the radii of curvature of portions 41 and 42 are larger than those of portions 43 and 44.

[0036] In addition, Figures 1 to 4 In one example, the cross-sectional shape of the connecting passage 32 is formed as a circle or approximately a circle. Furthermore, the diameter of the circle forming the cross-sectional shape of the connecting passage 32 is smaller than the major axis of the ellipse of the opening 31. In the oil flow path 23, a cross-sectional shape change portion 33 is formed between the opening 31 and the connecting passage 32. At the cross-sectional shape change portion 33, the cross-sectional shape of the oil flow path 23 changes smoothly between the ellipse of the opening 31 and the cross-sectional shape of the connecting passage 32, i.e., a circle. Additionally, in... Figures 1 to 4 In one example, the central axis A1 of the opening 31 is coaxial or substantially coaxial with the central axis A2 of the connecting path 32. Therefore, the opening 31 is formed to be coaxial or substantially coaxial with the connecting path 32. Furthermore, in Figures 1 to 4 In one example, the opening 35 forming the outlet is circular or substantially circular. Furthermore, the cross-sectional shape of the connecting path 36 is the same as or substantially the same as the opening 35, being circular or substantially circular. Additionally, the opening 35 is formed coaxially or substantially coaxially with the connecting path 36.

[0037] As described above, in the embodiments, the opening 31 of the oil flow path 23 opens towards the bottom at the piston skirt 6, and the size L1 of the opening 31 along the extension direction of the pin hole 22 is larger than the size L2 of the opening 31 along the width direction of the piston 3. By providing such a structure, the thin-walled area of ​​the piston skirt 6 is expanded near the opening 31. During the cyclic operation of the internal combustion engine 1, a load F is applied to the piston 3 from the width direction. The load F includes the side pressure between the piston and the cylinder 2 and the rotational force caused by the swaying motion, etc. In the embodiments, as described above, since the thin-walled area of ​​the piston skirt 6 is expanded, the rigidity of the piston skirt 6 relative to the load F is reduced (mitigated). In particular, the rigidity of the piston skirt 6 is reduced near the opening 31. By reducing the rigidity of the piston skirt 6, the frictional loss during the reciprocating motion of the piston 3 is reduced.

[0038] Furthermore, in one example of the embodiment, at the opening edge of the opening 31 of the oil flow path 23, the radii of curvature of the portions 41 and 42 that connect to the opening 31 in the width direction of the piston 3 are larger than the radii of curvature of the portions 43 and 44 that connect to the opening 31 in the extending direction from the pin hole 22. Because the radii of curvature of the portions 41 and 42 are larger, even if the piston skirt 6 is subjected to a load F in the width direction, the reaction force from the piston skirt 6 relative to the load F is reduced. Since the reaction force from the piston skirt 6 relative to the load F is reduced, the rigidity of the piston skirt 6 relative to the load F is further reduced.

[0039] In addition, Figures 1 to 4 In one example, the opening 31 of the oil flow path 23 is formed as an ellipse with its major axis extending along the direction of the pin hole 22. Therefore, at the opening 31, a structure in which dimension L1 is greater than dimension L2 is appropriately realized, and at the opening edge of the opening 31, a structure in which the radii of curvature of each part 41 and 42 are greater than the radii of curvature of each part 43 and 44 is appropriately realized.

[0040] Furthermore, in one example of the embodiment, the opening 31, which serves as the inflow section, is formed coaxially with the connecting passage 32. By configuring it in this way, backflow caused by oil flowing into the oil flow path 23 from the opening 31 impacting the wall surface is appropriately prevented. As a result, the oil flowing in from the opening 31 can easily reach the cooling chamber 26, and the oil collection rate is improved.

[0041] Figure 5 This is a schematic diagram of the opening 31 of the inlet portion forming the oil flow path 23 and its surrounding structure, viewed from the bottom side in a piston 3 of a certain modified example. Figure 5In the modified example, the size L1 of the opening 31 along the extension direction of the pin hole 22 is larger than the size L2 of the opening 31 along the width direction of the piston 3. Furthermore, the opening edge of the opening 31 has portions 41 and 42 that connect to the opening 31 in the width direction, and portions 43 and 44 that connect to the opening 31 in the extension direction (front-back direction) of the pin hole 22. Each of portions 41 to 44 is formed in an arc shape (curved shape) protruding away from the central axis A1 of the opening 31. However, in this modified example, the opening 31 is not formed in an elliptical shape. Furthermore, at the opening edge of the opening 31, a straight section is formed between each of portions 41 and 43 and 44, and a straight section is formed between each of portions 42 and 43 and 44.

[0042] In this modified example, similarly to the aforementioned embodiments, the radii of curvature of the portions 41 and 42 that connect to the opening 31 in the width direction at the opening edge of the opening 31 are greater than the radii of curvature of the portions 43 and 44 that connect to the opening 31 in the extending direction (front-back direction) of the pin hole 22. Due to this structure, in this modified example, the thin-walled area of ​​the piston skirt 6 near the opening 31 is expanded, and the reaction force from the piston skirt 6 relative to the load F in the width direction is reduced. Therefore, in this modified example, similarly to the aforementioned embodiments, the rigidity of the piston skirt 6 is reduced (mitigated).

[0043] Figure 6 In the context of Figure 5 A schematic diagram of the opening 31 of the inlet portion forming the oil flow path 23 and its surrounding structure, viewed from the bottom side in a different variant of the piston 3. Figure 6 In this modified example, the opening 31 is formed as a rounded rectangle. Furthermore, the opening edge of the opening 31 has a pair of long edges 45 and 46 that connect with the opening 31 in the width direction, and a pair of short edges 47 and 48 that connect with the opening 31 in the extension direction (front-back direction) of the pin hole 22. In this modified example, at the rounded rectangle of the opening 31, the long edges 45 and 46 are along the extension direction of the pin hole 22, and the short edges 47 and 48 are along the width direction of the piston 3. Therefore, at the opening 31, the long side direction of the rounded rectangle is along the front-back direction of the piston 3 (the extension direction of the pin hole 22).

[0044] Because of this structure, in this modified example, the size L1 of the opening 31 along the extending direction of the pin hole 22 is larger than the size L2 of the opening 31 along the width direction of the piston 3. Therefore, in this modified example, the thin-walled area of ​​the piston skirt 6 near the opening 31 is also enlarged. Therefore, in this modified example, similar to the aforementioned embodiments, the rigidity of the piston skirt 6 is reduced.

[0045] Furthermore, in embodiments, the shape of the opening 31 forming the inflow portion is not particularly limited as long as the size L1 of the opening 31 along the extension direction of the pin hole 22 is larger than the size L2 of the opening 31 along the width direction of the piston 3. For example, as long as the size L1 is larger than the size L2, the opening 31 can also be formed as a rounded polygon other than a rounded rectangle, such as a rounded triangle. By setting the structure so that the size L1 is larger than the size L2, the thin-walled area of ​​the piston skirt 6 near the opening 31 is expanded, and the rigidity of the piston skirt 6 relative to the load F is reduced. In addition, in embodiments, it is preferable that the radius of curvature of the opening edge of the opening 31 is larger than the radius of curvature of the portion (e.g., 43, 44) that connects to the opening 31 in the width direction of the piston 3. By designing the structure in this way, the reaction force from the piston skirt 6 relative to the load F from the width direction is reduced, and the rigidity of the piston skirt 6 relative to the load F is further reduced.

[0046] Figure 7 It is a general representation of... Figure 5 and Figure 6 A cross-sectional view of piston 3 in a different variant example. Figure 7 The image shows a cross-section that is orthogonal or substantially orthogonal to the width direction of piston 3 and passes through opening 31 and connecting passage 32. Figure 7 In a modified example, the size L1 of the opening 31 along the extension direction of the pin hole 22 is larger than the size L2 of the opening 31 along the width direction of the piston 3. Furthermore, the opening 31 forming the inflow portion is appropriately shaped so that the size L1 is larger than the size L2; in one example, it is formed to be... Figure 1 An example of the same oval shape.

[0047] In this modified example, the central axis A2 of the connecting path 32 is inclined relative to the vertical direction and the central axis A1 of the opening 31. Therefore, the central axis A1 of the opening 31 is not coaxial with the central axis A2 of the connecting path 32, and the opening 31 is formed to be non-coaxial with the connecting path 32. In this modified example, dimension L1 is also larger than dimension L2. Therefore, near the opening 31, the thin-walled area of ​​the piston skirt 6 is expanded, and the rigidity of the piston skirt 6 relative to the load F is reduced.

[0048] In the implementation methods, etc., at the opening 31, as long as the structure has a dimension L1 greater than the dimension L2, it can also be as follows: Figure 7As in the modified example, the opening 31 is not coaxial with the connecting passage 32. However, in the embodiments, it is preferable that the opening 31 is coaxial or substantially coaxial with the connecting passage 32. By setting it in this way, the oil flowing in from the opening 31 can easily reach the cooling chamber 26, and the oil collection rate is improved.

[0049] Furthermore, in the aforementioned embodiments, the cross-sectional shape of the connecting path 32 is formed to be different from the shape of the opening 31. However, in a certain variation, the cross-sectional shape of the connecting path 32 may also be formed to be the same as or substantially the same as the shape of the opening 31. In one example, with... Figures 1 to 4 Similarly, in another example, the opening 31 is formed as an ellipse with its major axis along the extension direction of the pin hole 22. Furthermore, the cross-sectional shape of the connecting passage 32 is formed as an ellipse that is the same as or substantially the same as that of the opening 31.

[0050] Furthermore, in the aforementioned embodiments, the opening 35 forming the outflow portion opens in the piston skirt 6, but is not limited to this. In a certain variation, the opening 35 opens towards the bottom at the lower surface 16 of the piston head 5. In this case, the opening 31 forming the inflow portion is also formed with the same shape as in any of the aforementioned embodiments. Therefore, in this variation, the size L1 of the opening 31 along the extending direction of the pin hole 22 is also larger than the size L2 of the opening 31 along the width direction of the piston 3.

[0051] Furthermore, in a certain variation, the opening 35, which becomes the outlet, opens towards the bottom at the piston skirt 6. Instead of forming the opening 31, which becomes the inlet, into any of the aforementioned shapes, or based on forming the opening 31 into any of the aforementioned shapes, the opening 35 is formed into the shape shown below. That is, in this variation, the size of the opening 35 along the extension direction of the pin hole 22 is larger than the size of the opening 35 along the width direction of the piston 3. By providing such a structure, the thin-walled area of ​​the piston skirt 6 is expanded near the opening 35 forming the outlet, and the rigidity of the piston skirt 6 relative to the load F is reduced.

[0052] Furthermore, in this modified example, it is preferable that the radius of curvature at the opening edge of the opening 35, compared to the radius of curvature at the portion where it connects to the opening 35 in the extending direction from the pin hole 22, is larger in the portion where it connects to the opening 35 in the width direction of the piston 3. In this case, the opening 35 is, for example, formed as an ellipse with its major axis along the extending direction of the pin hole 22. By adopting such a structure, the reaction force from the piston skirt 6 relative to the load F in the width direction is reduced, and the rigidity of the piston skirt 6 relative to the load F is further reduced.

[0053] In addition, the internal combustion engine 1 having the aforementioned piston 3 is, for example, mounted in a vehicle. Figure 8 This is a schematic diagram illustrating an example of the structure of a vehicle 100 equipped with the internal combustion engine 1 according to the embodiment. Figure 8 As shown, vehicle 100 has an internal combustion engine 1, a transmission 101, and one or more wheels 102. Figure 8 One example shows a four-wheeled vehicle with four wheels 102, but the number of wheels 102 is not particularly limited. In the vehicle 100, the internal combustion engine 1 operates cyclically, thereby transmitting driving force via the gearbox 101 to any one or more of the wheels 102. Because driving force is transmitted to any one or more of the wheels 102, the vehicle 100 is able to move. Figure 8 One example is that, with four wheels 102, it can be a two-wheel drive where the driving force is transmitted to two wheels 102, or a four-wheel drive where the driving force is transmitted to all four wheels 102.

[0054] Furthermore, the present invention is not limited to the above-described embodiments, and various modifications can be made during implementation without departing from its spirit. Additionally, the embodiments can be implemented in appropriate combinations, resulting in combined effects. Moreover, the above embodiments include various inventions, and various inventions can be extracted by selecting combinations from the disclosed multiple structural elements. For example, if the problem can be solved and the desired effect obtained even if several structural elements are deleted from all the structural elements shown in the embodiments, then the structure after deleting those structural elements can also be extracted as an invention.

Claims

1. A piston having: Piston head; A piston skirt, disposed on the bottom side relative to the piston head, and having a pin hole formed along an extending direction intersecting the vertical direction; and An oil flow path extends through the piston head and the piston skirt, and has an opening at the piston skirt that opens toward the bottom side. The size of the opening along the extending direction of the pin hole is larger than the size of the opening along the width direction that intersects both the vertical direction and the extending direction of the pin hole.

2. The piston according to claim 1, wherein, At the opening edge of the opening in the oil flow path, the radius of curvature of the portion that connects to the opening in the width direction is larger than the radius of curvature of the portion that connects to the opening in the extension direction of the pin hole.

3. The piston according to claim 2, wherein, The opening of the oil flow path is formed as an ellipse with its major axis along the extension direction of the pin hole.

4. The piston according to claim 1, wherein, The oil flow path includes a cooling chamber formed inside the piston head and a connecting passage that connects the opening to the cooling chamber. The opening is formed to be coaxial with the connecting path.

5. The piston according to claim 1, wherein, The opening forms an inlet for oil from the fuel injector to flow into the oil flow path.

6. An internal combustion engine, comprising: The piston according to any one of claims 1 to 5; and The fuel injector is capable of injecting engine oil and directing the injected engine oil into the oil flow path of the piston.

7. A vehicle having the internal combustion engine of claim 6.

Images