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JP-2026075975-A - Internal combustion engine

JP2026075975AJP 2026075975 AJP2026075975 AJP 2026075975AJP-2026075975-A

Abstract

[Problem] To provide an internal combustion engine that can improve the space utilization rate of the combustion chamber and improve thermal efficiency. [Solution] The internal combustion engine comprises a cylinder, a piston disposed inside the cylinder and having a top surface facing other members with an axial gap between them, and a fuel injector that injects fuel into the axial gap, the fuel injector having an injection center axis inclined toward the radially inward side of the cylinder and toward the downstream side in the direction of swirl flow, wherein at least one cavity formed on the top surface of the piston has a ridge extending along the radial direction of the piston at a circumferential position of the piston where the fuel injector is located, and an inclined surface that is inclined such that the depth of the cavity increases as it moves away from the ridge toward the downstream side in the direction of swirl flow. [Selection Diagram] Figure 2

Inventors

  • 首藤 進太郎
  • 上田 哲司
  • 蝋山 大樹
  • 佐々木 俊也

Assignees

  • 三菱重工業株式会社

Dates

Publication Date
20260511
Application Date
20241023

Claims (13)

  1. Cylinder and A piston is disposed inside the cylinder and has a top surface that faces another member with an axial gap between them, The system comprises at least one fuel injection device configured to inject fuel into the axial gap inside the cylinder, and having an injection center axis inclined toward the radially inward side of the cylinder toward the downstream side in the direction of swirl flow, At least one cavity formed on the top surface of the piston is At the circumferential position of the piston where the at least one fuel injector is located, a ridge portion extends along the radial direction of the piston, The system includes an inclined surface that slopes such that the depth of the cavity increases as it moves away from the peak portion downstream in the direction of the swirl flow, Internal combustion engine.
  2. The aforementioned at least one cavity is A downstream ridge portion extending along the radial direction of the piston, downstream of the inclined surface in the flow direction of the swirl flow, The present invention further comprises a rising surface that slopes such that the depth of the cavity increases as it moves away from the downstream ridge portion to the upstream side in the flow direction of the swirl flow, The inclined surface has a smaller inclination in the flow direction of the swirl flow than the rising surface. The internal combustion engine according to claim 1.
  3. The aforementioned piston is A groove provided on the top surface of the outer peripheral portion covering the outer circumference of the cavity, which connects the radially inner and outer sides of the outer peripheral portion, and having a groove provided downstream of the inclined surface in the flow direction of the swirl flow, An internal combustion engine according to claim 1 or 2.
  4. When the piston is viewed from one side in the axial direction of the cylinder, and the circumferential position of the fuel injection device is defined as 0°, and the circumferential angle θ is defined as the positive direction of the swirl flow, the circumferential center of the groove is provided at a circumferential position where the circumferential angle θ is 90° or more. The internal combustion engine according to claim 3.
  5. The other member is an opposing piston located on one side of the cylinder in the axial direction relative to the piston inside the cylinder, and having an opposing top surface that faces the top surface of the piston with an axial gap between them. A scavenging port is formed on the scavenging side, which is the other side in the axial direction of the cylinder, and an exhaust port is formed on the exhaust side, which is the one side in the axial direction of the cylinder. An internal combustion engine according to claim 1 or 2.
  6. The aforementioned piston is A groove provided on the top surface of the outer peripheral portion covering the outer circumference of the cavity, which connects the radially inner and outer sides of the outer peripheral portion, and having a groove provided downstream of the inclined surface in the flow direction of the swirl flow, The groove portion has a central axis that is inclined toward the radially inward direction toward the downstream side in the flow direction of the swirl flow. The internal combustion engine according to claim 5.
  7. The aforementioned piston is A groove provided on the top surface of the outer peripheral portion covering the outer circumference of the cavity, which connects the radially inner and outer sides of the outer peripheral portion, and having a groove provided downstream of the inclined surface in the flow direction of the swirl flow, The groove portion is such that the groove width at the outer end in the radial direction is greater than the groove width at the inner end. The internal combustion engine according to claim 5.
  8. At least one opposing cavity formed on the opposing top surface of the opposing piston is At the circumferential position of the opposing piston on which the at least one fuel injection device is located, the opposing side crest portion extends along the radial direction of the opposing piston, The system includes an opposing inclined surface that slopes such that the depth of the opposing cavity increases as it moves away from the opposing crest portion downstream in the flow direction of the swirl flow, The internal combustion engine according to claim 5.
  9. The at least one fuel injection device is The first fuel injection device includes an injection center axis that is inclined toward the scavenging side in the axial direction toward the radially inward direction, The inclined surface of the cavity through which the fuel injected from the first fuel injector is guided has a greater inclination in the flow direction of the swirl flow than the opposing inclined surface of the opposing cavity through which the fuel injected from the first fuel injector is guided. The internal combustion engine according to claim 8.
  10. The at least one fuel injection device is A second fuel injection device is positioned circumferentially offset from the first fuel injection device so as to face the central axis of the cylinder when viewed from one side in the axial direction of the cylinder, and further includes a second fuel injection device having an injection central axis inclined toward the exhaust side in the axial direction toward the radially inward direction, The opposing inclined surface of the opposing cavity through which the fuel injected from the second fuel injector is guided has a greater inclination in the flow direction of the swirl flow than the inclined surface of the cavity through which the fuel injected from the second fuel injector is guided. The internal combustion engine according to claim 9.
  11. The piston has a projection that extends radially inward from the cavity and protrudes beyond the bottom surface of the cavity, and the inner circumferential end of the ridge portion is connected to the projection. An internal combustion engine according to claim 1 or 2.
  12. The aforementioned projection has a flat surface at its tip that extends along the radial direction. The internal combustion engine according to claim 11.
  13. The aforementioned other member is a cylinder head that covers the opening on one side in the axial direction of the cylinder. An internal combustion engine according to claim 1 or 2.

Description

This disclosure relates to internal combustion engines. Two-stroke diesel engines (internal combustion engines) include opposed-piston engines, in which two pistons are arranged facing each other inside a single cylinder, forming a combustion chamber between the two pistons (for example, Patent Document 1). In an opposed-piston engine, during one reciprocating motion of the pistons, an exhaust stroke occurs in which combustion gases inside the cylinder are discharged through an exhaust port formed in the cylinder wall, and a scavenging stroke occurs in which air is drawn into the cylinder through a scavenging port formed in the cylinder wall. Patent No. 5782109 This is a schematic cross-sectional view of an internal combustion engine according to one embodiment of the present disclosure.This is a schematic perspective view of a piston in one embodiment of the present disclosure.This is an explanatory diagram illustrating the cavity shape of a piston in one embodiment of the present disclosure.This is a schematic perspective view of the opposing piston in one embodiment of the present disclosure.This is an explanatory diagram illustrating the cavity shape of the opposing piston in one embodiment of the present disclosure.This is a schematic cross-sectional view showing the vicinity of the first combustion chamber of an internal combustion engine according to one embodiment of the present disclosure.This is a schematic cross-sectional view showing the vicinity of the second combustion chamber of an internal combustion engine according to one embodiment of the present disclosure.This is an explanatory diagram illustrating a scavenging port of an internal combustion engine according to one embodiment of the present disclosure.This is an explanatory diagram illustrating the groove portion of a piston in one embodiment of the present disclosure.This is an explanatory diagram illustrating the groove portion of a piston in one embodiment of the present disclosure.This is a schematic cross-sectional view of an internal combustion engine according to one embodiment of the present disclosure. Several embodiments of this disclosure will be described below with reference to the attached drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the components described or shown in the drawings as embodiments are not intended to limit the scope of this disclosure, but are merely illustrative examples. (Internal combustion engine) Figure 1 is a schematic cross-sectional view of an internal combustion engine 1 according to one embodiment of the present disclosure. The internal combustion engine 1 according to some embodiments comprises a cylinder 2, a piston 3, and at least one fuel injector 5. An internal space 20 is formed inside the cylinder 2, extending along the axial direction of the cylinder 2. The cylinder 2 has an outer surface 21 and an inner surface 22 that forms the internal space 20, located radially inward from the outer surface 21. In the illustrated embodiment, the cylinder 2 is formed in a cylindrical shape extending along the axial direction of the cylinder 2. Both the outer surface 21 and the inner surface 22 of the cylinder 2 have a circular cross-sectional shape perpendicular to the axial direction of the cylinder 2. The piston 3 is positioned inside the cylinder 2 (internal space 20) and has a top surface 31 and an outer circumferential surface 32 that face each other with an axial gap between them and the other member 100. In the embodiment shown in Figure 1, the internal combustion engine 1 is an opposed-piston engine, and the other member 100 is the opposing piston 4 of the opposed-piston engine. The opposing piston 4 is positioned inside the cylinder 2 (internal space 20) on one side of the cylinder 2 in the axial direction relative to the piston 3. The opposing piston 4 has an opposing top surface 41 and an outer circumferential surface 42 that face each other with an axial gap between them and the top surface 31 of the piston 3. Hereinafter, the other axial side of cylinder 2 (upper side in Figure 1) is defined as the scavenging side, and the aforementioned axial side of cylinder 2 (lower side in Figure 1) is defined as the exhaust side. Piston 3 is the scavenging side piston and is arranged to reciprocate along the axial direction of cylinder 2 within the scavenging side of the internal space 20. The opposing piston 4 is the exhaust side piston and is arranged to reciprocate along the axial direction of cylinder 2 within the exhaust side of the internal space 20. The top surface 31 is the exhaust-side end face of the piston 3. The opposing top surface 41 is the scavenging-side end face of the opposing piston 4. In the cylinder 2, a combustion chamber 11 is formed between the top surface 31 and the opposing top surface 41 in the internal space 20. In other words, the top surface 31 faces the opposing top surface 41 in the axial direction of the cylinder 2, with the com