Piston and internal combustion engine
By forming a groove in the piston skirt as a flow path, the problem of lubricating oil being difficult to guide to the cylinder inner wall surface is solved, thus achieving effective utilization of lubricating oil, reducing friction, and improving lubrication effect.
Patent Information
- Application Number
- CN202511017111.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-07-30
- Filing Date
- 2025-07-23
- Publication Date
- 2026-02-03
AI Technical Summary
Existing technologies cannot effectively utilize the lubricating oil discharged from the cooling chamber to form an oil film on the cylinder inner wall surface, resulting in the lubricating oil being difficult to guide to the cylinder inner wall surface, thus increasing friction.
A groove is formed in the skirt of the piston to serve as a flow path, allowing the lubricating oil discharged from the outlet to flow along the inner circumferential surface and be directly guided to the inner wall surface of the cylinder to form an oil film.
The groove design effectively utilizes lubricating oil to form an oil film on the inner wall surface of the cylinder, reducing friction and improving lubrication.
Smart Images
Figure CN121452091A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to pistons and internal combustion engines. Background Technology
[0002] The piston of the internal combustion engine is provided with a cooling chamber, through which lubricating oil flows within the piston head to cool the piston head, which has reached a high temperature (see Japanese Unexamined Patent Application Publication No. 2019-39340). The lubricating oil flowing through the cooling chamber is discharged from an outlet communicating with the cooling chamber and falls into the oil pan in the lower part of the internal combustion engine. Summary of the Invention
[0003] The problem that the invention aims to solve
[0004] To reduce friction that occurs when the piston slides relative to the cylinder, a lubricating oil film is formed on the inner wall surface of the cylinder. Although it is possible to supply lubricating oil discharged from the outlet to the inner wall surface of the cylinder to maintain the oil film, it is difficult to guide the lubricating oil discharged from the outlet to the inner wall surface of the cylinder because the outlet is located far from the inner wall surface of the cylinder.
[0005] This disclosure has been made with these points in mind, and the purpose of this disclosure is to effectively utilize the lubricating oil discharged from the cooling chamber.
[0006] Methods for solving problems
[0007] A first aspect of this disclosure provides a piston that reciprocates within a cylinder. The piston includes: a piston head having a combustion chamber formed on a top surface; a cooling section formed in an annular cavity within the piston head, through which lubricating oil flows; an outlet communicating with the cooling section and discharging lubricating oil from the cooling section to a lower side of the piston head; and a skirt extending downward from a lower end of the outer periphery of the piston head, wherein the skirt includes a flow path formed in an inner peripheral surface opposite to the outer peripheral surface facing the cylinder, and lubricating oil discharged from the outlet flows along the inner peripheral surface through the flow path.
[0008] Furthermore, the flow path portion can be formed in the inner circumferential surface all the way to the lower end of the skirt portion.
[0009] In addition, the flow path portion can be a groove portion, in which the inner circumferential surface of the skirt portion is recessed along the axial direction of the piston.
[0010] Furthermore, the distance between the bottom surface of the groove portion and the outer peripheral surface of the skirt portion can be reduced towards the lower end of the skirt portion.
[0011] In addition, the width of the trough in the direction perpendicular to the vertical direction can be greater than the diameter of the outlet.
[0012] Furthermore, the width of the groove portion in the direction perpendicular to the vertical direction can be increased toward the lower end of the skirt portion.
[0013] Furthermore, the flow path portion can be formed in the inner circumferential surface to extend from the upper end to the lower end of the skirt portion.
[0014] In addition, the thickness of the skirt can decrease from the top to the bottom.
[0015] In addition, the flow path can be connected to a discharge path having a discharge outlet formed at the distal end.
[0016] A second aspect of this disclosure provides an internal combustion engine including a cylinder and a piston reciprocating within the cylinder, wherein the piston includes: a piston head having a combustion chamber formed on a top surface; a cooling section formed in an annular cavity within the piston head, through which lubricating oil flows; an outlet communicating with the cooling section and discharging lubricating oil from the cooling section to a lower side of the piston head; and a skirt extending downward from a lower end of the outer periphery of the piston head, wherein the skirt includes a flow path formed in an inner peripheral surface opposite to the outer peripheral surface facing the cylinder, and lubricating oil discharged from the outlet flows along the inner peripheral surface through the flow path.
[0017] Invention Effects
[0018] According to this disclosure, lubricating oil discharged from the piston's cooling chamber can be effectively utilized. Attached Figure Description
[0019] Figure 1 This is a schematic diagram showing the configuration of the internal combustion engine 1 according to an embodiment.
[0020] Figure 2 This is a schematic diagram showing the internal configuration of piston 30.
[0021] Figure 3 It is along Figure 2 The sectional view taken from line II.
[0022] Figure 4 This is a view of piston 30 from below. Detailed Implementation
[0023] <Internal Combustion Engine Configuration>
[0024] Figure 1 This is a schematic diagram illustrating the configuration of an internal combustion engine 1 according to one embodiment. Here, the internal combustion engine 1 is mounted on a vehicle such as a truck, but is not limited thereto, and can also be mounted on, for example, a ship.
[0025] The internal combustion engine 1 is, for example, a diesel engine. The internal combustion engine 1 is a power source that generates power to propel a vehicle by burning and expanding the air-fuel mixture in the combustion chamber 2. The internal combustion engine 1 includes a cylinder block 10, a cylinder head 20, a piston 30, a crankshaft 60, and an injection section 70.
[0026] The cylinder block 10 includes a cylinder 12 and a crankcase 16 that houses a crankshaft 60. The cylinder 12 houses the piston 30 in a manner that allows the piston 30 to reciprocate. An oil pan 18 that stores lubricating oil is attached to the crankcase 16.
[0027] The cylinder head 20 is disposed on the upper part of the cylinder block 10. The cylinder head 20 includes an injector 22, an intake valve 25, and an exhaust valve 26. The injector 22 injects fuel into the combustion chamber 2 defined by the top surface of the piston 30, the inner wall surface 13 of the cylinder 12, and the cylinder head 20. The intake valve 25 opens and closes to introduce fresh air into the combustion chamber 2 from the intake port 23. The exhaust valve 26 opens and closes to guide exhaust gas from the combustion chamber 2 into the exhaust port 24.
[0028] Piston 30 reciprocates within cylinder 12. As piston 30 reciprocates between top dead center and bottom dead center, it slides on the inner wall surface 13 of cylinder 12. Lubricating oil is supplied to the inner wall surface 13 to form an oil film. The formation of this oil film on the inner wall surface 13 reduces friction as piston 30 slides on it. The detailed configuration of piston 30 will be described later.
[0029] The crankshaft 60 is connected to the piston 30 via a connecting rod (hereinafter referred to as "connecting rod") 62. The crankshaft 60 converts the reciprocating motion of the piston 30 into rotational motion.
[0030] The injection section 70 sprays lubricating oil toward the piston 30. For example, when the piston 30 is at bottom dead center, the injection section 70 sprays lubricating oil upward toward the piston 30 located above it. Specifically, the injection section 70 sprays lubricating oil toward the inlet 42 of the piston 30. Figure 2 The lubricating oil is sprayed upwards, thereby supplying the lubricating oil to the cooling section 40 of the piston 30. Figure 2 ).
[0031] <Internal Configuration of Pistons>
[0032] Reference Figures 2 to 4 Describe the internal configuration of piston 30.
[0033] Figure 2 This is a schematic diagram showing the internal configuration of piston 30. Figure 3 It is along Figure 2 The sectional view taken from line II. Figure 4 This is a view of piston 30 taken from below. (As shown) Figure 2As shown, the piston 30 includes a piston head 32, a connecting portion 35, a skirt portion 36, a cooling portion 40, an inlet 42, an outlet 44, and a groove portion 50.
[0034] The piston head 32 is a cylindrical portion formed on the upper part of the piston 30. A cavity 33, recessed relative to the top surface, is provided at the center of the top surface of the piston head 32. The cavity 33, together with the cylinder 12 and cylinder head 20, forms a combustion chamber 2 in which fuel and air are burned. Figure 1 Fuel is supplied from injector 22 ( Figure 1 The gas is injected into cavity 33. Grooves 34, in which piston rings are mounted, are formed on the outer peripheral surface of piston head 32. The piston rings are used to seal combustion gases and maintain an oil film of a predetermined thickness on the inner wall surface 13 of cylinder 12. Figure 2 For ease of explanation, piston rings have been omitted.
[0035] Here, the connecting portion 35 is a piston pin, connecting the piston 30 and the connecting rod 62. The connecting portion 35 is cylindrical and fits into the pin hole of the piston 30. The connecting portion 35 is configured to... Figure 2 The front of the plane extends to the back.
[0036] The skirt portion 36 is the lower part of the piston 30. The skirt portion 36 extends downward from the lower end of the outer periphery of the piston head 32. The skirt portion 36 is cylindrical. The skirt portion 36 is provided to suppress tilting of the piston 30 within the cylinder 12. The skirt portion 36 is formed such that its thickness decreases towards the lower end 39.
[0037] The skirt portion 36 is disposed around the entire circumference of the piston 30, but only on the portion facing the inner wall surface 13 of the cylinder 12, specifically in the thrust and anti-thrust regions. The thrust region of the inner wall surface 13 is the area in which the skirt portion 36 slides when the piston 30 moves from top dead center to bottom dead center. The anti-thrust region of the inner wall surface 13 is the area in which the skirt portion 36 slides when the piston 30 moves from bottom dead center to top dead center. Figure 2 In the middle, the upper left part viewed from piston 30 is the thrust region, and the upper right part viewed from piston 30 is the anti-thrust region.
[0038] The skirt portion 36 includes a skirt portion 36A located on the left side of the connecting portion 35 and a skirt portion 36B located on the right side of the connecting portion 35. Skirt portion 36A faces the thrust region, while skirt portion 36B faces the anti-thrust region. Skirt portions 36A and 36B are arranged symmetrically with respect to the connecting portion 35.
[0039] The cooling section 40 is a lubrication path lubricated by lubricating oil, used to cool the piston head 32 which reaches high temperatures. The cooling section 40 is formed in an annular cavity within the piston head 32. This cavity serves as a cooling chamber through which the lubricating oil flows. The cooling section 40 is formed around the periphery of the cavity 33.
[0040] Inlet 42 communicates with cooling section 40 and is an opening for introducing lubricating oil into cooling section 40. Inlet 42 is located in the lower part of piston head 32 and communicates with cooling section 40 via introduction path 43. Introduction path 43 is formed vertically in piston head 32. Inlet 42 is located at the lower end, which is the distal end of introduction path 43. Inlet 42 is formed in the thrust region of piston head 32 facing inner wall surface 13 of cylinder 12.
[0041] Inlet 42 will be injected by injection section 70 when piston 30 is at bottom dead center. Figure 1 The injected lubricating oil is directed to the cooling section 40. An inlet 42 is formed where, when the piston 30 is at bottom dead center, the injection section 70 is located directly below the inlet 42. The lubricating oil introduced into the cooling section 40 from the inlet 42 circulates within the chamber of the cooling section 40.
[0042] The outlet 44 communicates with the cooling section 40 and is an opening for discharging lubricating oil flowing through the cooling section 40. The outlet 44 is located in the lower part of the piston head 32 and communicates with the cooling section 40 via a discharge path 45. The outlet 44 is formed vertically in the piston head 32. The outlet 44 is located at the lower end, which is the distal end of the discharge path 45. The outlet 44 is formed in the thrust region of the piston head 32 facing the inner wall surface 13 of the cylinder 12.
[0043] The outlet 44 discharges the lubricating oil that flows from the cooling section 40 through the discharge path 45 to the underside of the piston head 32. For example, when the piston 30 moves from the bottom dead center to the top dead center, the lubricating oil flowing through the cooling section 40 flows into the discharge path 45.
[0044] In this embodiment, in order to effectively utilize the lubricating oil discharged from the outlet 44, the skirt portion 36 (here, the skirt portion 36A on the thrust region side of the inner wall surface 13) has a flow path portion that guides the lubricating oil discharged from the outlet 44 from the rear surface (inner peripheral surface 37) side of the skirt portion 36A to the inner wall surface 13 of the cylinder 12. Specifically, the flow path portion is a flow path that supplies the lubricating oil discharged from the outlet 44 between the thrust region of the inner wall surface 13 of the cylinder 12 and the skirt portion 36A when the piston 30 descends. Therefore, since a large amount of lubricating oil is supplied between the thrust region of the inner wall surface 13 and the skirt portion 36A, an oil film with a large thickness is formed in the thrust region. As a result, during the descent of the piston 30, the frictional force when the skirt portion 36A slides against the thrust region of the inner wall surface 13 can be suppressed.
[0045] In this embodiment, the flow path portion is a groove portion 50 formed in the inner peripheral surface 37 opposite to the outer peripheral surface 38 of the skirt portion 36A facing the cylinder 12. The groove portion 50 allows lubricating oil discharged from the outlet 44 to flow along the inner peripheral surface 37. Specifically, the lubricating oil discharged from the outlet 44 flows along the groove portion 50 due to intermolecular forces and inertial forces. When the lubricating oil flows along the groove portion 50 (the lubricating oil is like...), Figure 2 When the flow is as indicated by arrow D in the diagram, the lubricating oil is more likely to adhere to the inner wall surface 13 of cylinder 12. As a result, it can prevent the lubricating oil discharged from outlet 44 from falling into oil pan 18. Figure 1 (and thus it was not utilized.)
[0046] The groove portion 50 extends from the inner circumferential surface 37 to the lower end 39 of the skirt portion 36A. As a result, due to intermolecular forces and inertial forces, lubricating oil flows more easily along the groove portion 50 to the lower end 39 of the skirt portion 36A. This facilitates the movement of lubricating oil from the lower end 39 to the inner wall surface 13 of the cylinder 12, making it more likely that the lubricating oil will adhere to the inner wall surface 13.
[0047] In this embodiment, since the skirt portion 36A has a small thickness, the groove portion 50, which serves as a flow path portion, is formed in the inner peripheral surface 37 of the skirt portion 36A. In particular, the groove portion 50, which also extends to the lower end 39 of the skirt portion 36A, makes it easier for lubricating oil to move from the lower end 39 to the inner wall surface 13 of the cylinder 12.
[0048] The groove portion 50 is formed in the inner circumferential surface 37 extending from the upper end to the lower end of the skirt portion 36A. This increases the amount of lubricating oil flowing through the groove portion 50. As a result, a large amount of lubricating oil adheres from the lower end of the skirt portion 36A to the inner wall surface 13 of the cylinder 12, and the thickness of the oil film increases.
[0049] The thickness of the skirt portion 36A decreases from its upper end to its lower end 39. Therefore, the distance between the bottom surface of the groove portion 50 and the outer peripheral surface 38 of the skirt portion 36A decreases towards the lower end 39 of the skirt portion 36A. As a result, because the radial distance between the lower end 39 of the skirt portion 36A and the inner wall surface 13 of the cylinder 12 is short, the lubricating oil flowing along the bottom surface of the groove portion 50 can more easily move from the lower end of the skirt portion 36A to the inner wall surface 13 of the cylinder 12.
[0050] The groove portion 50 is a groove portion in which the inner circumferential surface 37 of the skirt portion 36A is recessed along the axial direction of the piston 30. Here, the depth of the groove portion 50 is constant, and is, for example, approximately the same as the diameter of the outlet 44. On the other hand, the width of the groove portion 50 in the orthogonal direction perpendicular to the vertical direction ( Figure 3 The width L shown increases towards the lower end of the skirt portion 36A. Therefore, as... Figure 3As shown, the groove portion 50 has a trapezoidal shape. Although the depth of the groove portion 50 is constant in the above description, the depth of the groove portion 50 is not limited to being constant and can vary.
[0051] For example, the width of the lower end of the groove portion 50 in the orthogonal direction is set to be the same as the width of the inner wall surface 13 in the circumferential direction of the thrust region. In this way, the lubricating oil discharged from the outlet 44 can more easily adhere to the entire thrust region of the inner wall surface 13. Therefore, the thickness of the oil film in the thrust region of the inner wall surface 13 is increased, thereby reducing the frictional force when the skirt portion 36A slides in the thrust region of the inner wall surface 13 as the piston 30 moves from the top dead center to the bottom dead center.
[0052] The groove portion 50 is connected to the discharge path 45. This facilitates the flow of lubricating oil through the discharge path 45 along the groove portion 50. Furthermore, the width of the groove portion 50 in the orthogonal direction perpendicular to the vertical direction is greater than the diameter of the discharge outlet 44. As a result, since the area through which the lubricating oil flows in the groove portion 50 can be widened, most of the lubricating oil flowing through the discharge path 45 flows more easily along the groove portion 50.
[0053] In the above description, the groove portion 50 is a flow path portion through which lubricating oil discharged from the outlet 44 flows along the inner circumferential surface 37 of the skirt portion 36A. However, this disclosure is not limited to this, and for example, a hole portion configured to pass through the skirt portion 36A along the inner circumferential surface 37 can also be a flow path portion. Even in this case, the lubricating oil discharged from the outlet 44 can still be guided to the inner wall surface 13 of the cylinder 12.
[0054] <Effects of this implementation method>
[0055] The piston 30 according to this embodiment includes a discharge port 44 and a skirt portion 36A. The discharge port 44 discharges lubricating oil from the cooling portion 40 to the lower side of the piston head 32, and the skirt portion 36A extends downward from the lower end of the outer periphery of the piston head 32. The skirt portion 36A includes a groove portion 50, which is formed on an inner peripheral surface 37 opposite to the outer peripheral surface 38 facing the cylinder 12, and serves as a flow path portion through which the lubricating oil discharged from the discharge port 44 flows along the inner peripheral surface 37. As a result, the lubricating oil discharged from the discharge port 44 flows along the groove portion 50 formed in the inner peripheral surface 37 of the skirt portion 36A, and moves from the skirt portion 36A to the inner wall surface 13 of the cylinder 12, thereby forming an oil film of lubricating oil on the inner wall surface 13. Therefore, the lubricating oil discharged from the discharge port 44 can be effectively utilized.
[0056] This disclosure is based on exemplary embodiments. The technical scope of this disclosure is not limited to the scope described in the above embodiments, and various changes and modifications can be made within the scope of this disclosure. For example, all or part of the device may be configured with any functionally or physically distributed or integrated units. Furthermore, new exemplary embodiments resulting from any combination of exemplary embodiments are included in the exemplary embodiments. Moreover, the effects of new exemplary embodiments resulting from combinations also have the effects of the original exemplary embodiments.
[0057] [Symbol Description]
[0058] 1. Internal Combustion Engine
[0059] 12 cylinders
[0060] 30 Piston
[0061] 32 Piston Head
[0062] 36A skirt part
[0063] 37 inner peripheral surface
[0064] 38 Peripheral surface
[0065] 40 Cooling section
[0066] 44 Discharge outlets
[0067] 45 Discharge Path
[0068] 50 slots
Claims
1. A piston that reciprocates within a cylinder, the piston comprising: The piston head has a combustion chamber formed on its top surface; A cooling section is formed in an annular cavity within the piston head, and lubricating oil flows through the cooling section; The outlet is connected to the cooling section and discharges the lubricating oil from the cooling section to the lower side of the piston head; as well as The skirt portion extends downward from the lower end of the outer periphery of the piston head, wherein the skirt portion includes a flow path portion formed in an inner peripheral surface opposite to the outer peripheral surface facing the cylinder, and the lubricating oil discharged from the outlet flows along the inner peripheral surface through the flow path portion.
2. The piston according to claim 1, wherein, The flow path portion extends in the inner circumferential surface to the lower end of the skirt portion.
3. The piston according to claim 1, wherein, The flow path portion is a groove portion, in which the inner circumferential surface of the skirt portion is recessed along the axial direction of the piston.
4. The piston according to claim 3, wherein, The distance between the bottom surface of the groove portion and the outer peripheral surface of the skirt portion decreases towards the lower end of the skirt portion.
5. The piston according to claim 3, wherein, The width of the groove portion in the direction perpendicular to the vertical direction is greater than the diameter of the outlet.
6. The piston according to claim 3, wherein, The width of the groove portion increases toward the lower end of the skirt portion in a direction perpendicular to the vertical direction.
7. The piston according to claim 1, wherein, The flow path portion is formed in the inner circumferential surface to extend from the upper end to the lower end of the skirt portion.
8. The piston according to claim 7, wherein, The thickness of the skirt portion decreases from the upper end to the lower end.
9. The piston according to claim 1, wherein, The flow path portion is connected to a discharge path having the discharge outlet formed at the distal end.
10. An internal combustion engine, comprising: cylinder; as well as A piston reciprocates within the cylinder, wherein the piston comprises: The piston head has a combustion chamber formed on its top surface; A cooling section is formed in an annular cavity within the piston head, and lubricating oil flows through the cooling section; An outlet, connected to the cooling section, discharges the lubricating oil from the cooling section to the underside of the piston head; and The skirt portion extends downward from the lower end of the outer periphery of the piston head, wherein the skirt portion includes a flow path portion formed in an inner peripheral surface opposite to the outer peripheral surface facing the cylinder, and the lubricating oil discharged from the outlet flows along the inner peripheral surface through the flow path portion.