CN109751114B - Combustion chamber structure of internal combustion engine - Google Patents
Combustion chamber structure of internal combustion engine Download PDFInfo
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- CN109751114B CN109751114B CN201811291051.9A CN201811291051A CN109751114B CN 109751114 B CN109751114 B CN 109751114B CN 201811291051 A CN201811291051 A CN 201811291051A CN 109751114 B CN109751114 B CN 109751114B
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- flat portion
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- intake side
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B23/00—Other engines characterised by special shape or construction of combustion chambers to improve operation
- F02B23/08—Other engines characterised by special shape or construction of combustion chambers to improve operation with positive ignition
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F1/00—Cylinders; Cylinder heads
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F3/00—Pistons
- F02F3/28—Other pistons with specially-shaped head
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
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- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Combustion Methods Of Internal-Combustion Engines (AREA)
- Pistons, Piston Rings, And Cylinders (AREA)
Abstract
Provided is a combustion chamber structure of an internal combustion engine, wherein a valve recess, a bulge and a bowl are formed on the top surface of a piston, the combustibility of an air-fuel mixture can be easily improved, and the cooling loss of combustion gas can be easily reduced. The combustion chamber structure of an engine is provided with: an intake side peak portion passing through the intake side valve recess and the piston intake side flat portion; an exhaust side peak portion passing through the exhaust side valve recess portion and the piston exhaust side flat portion; and a 1 st joining peak and a 2 nd joining peak which join an end of the intake side peak and an end of the exhaust side peak and extend along an outer peripheral edge of a top surface of the piston in a radial direction, wherein a 1 st bowl portion is provided in a combustion chamber structure of the engine, and the 1 st bowl portion is recessed from the bulge portion toward a central axis of the piston.
Description
Technical Field
The present invention relates to a combustion chamber structure of an internal combustion engine.
Background
A technique for improving flame propagation performance by a combustion chamber structure in an internal combustion engine is proposed. (see patent document 1).
The reciprocating engine described in patent document 1 has a geometric compression ratio of 13.0 or more, a crown portion and a recess portion formed in an upper surface of a piston, and a combustion chamber is formed by forming a predetermined gap between the upper surface of the piston and a top surface of a cylinder head when the piston is positioned at a top dead center, so that the piston does not interfere with a virtual sphere having a predetermined radius around a spark plug.
Accordingly, the reciprocating engine described in patent document 1 can improve the geometric compression ratio by the raised portion, and improve the flame propagation property by the shape of the recessed portion, thereby improving the fuel efficiency of the reciprocating engine.
Documents of the prior art
Patent document
Patent document 1: japanese patent application laid-open No. 5003496
Disclosure of Invention
Problems to be solved by the invention
However, in the conventional reciprocating engine, since the bulge portion is largely bulged upward from the upper surface of the piston around the central axis of the piston (the central axis of the spark plug), when the piston approaches the top dead center, the vertical swirl collides with the bulge portion to attenuate the flow of air, and it is difficult to improve the mixing property of fuel and air.
Further, since the space of the valve recess (valve recess) and the recess in the raised portion are connected by the flat space, the air-fuel mixture entering the valve recess is difficult to burn. Further, the surface area of the combustion chamber is increased, and there is a possibility that a cooling loss of the combustion gas is increased.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a combustion chamber structure of an internal combustion engine, which has a valve recess, a bulge portion, and a bowl portion on a top surface of a piston, and which can easily improve combustibility of an air-fuel mixture and can easily reduce a cooling loss of a combustion gas.
Means for solving the problems
The present invention is a combustion chamber structure of an internal combustion engine, including a combustion chamber, the combustion chamber being formed by a cylinder block, a piston, and a cylinder head, the cylinder block including a cylinder, the piston being housed in the cylinder and being capable of reciprocating, the cylinder head being attached to the cylinder block, the cylinder head including: a ceiling wall of an inclined ridge shape, whereby the pair of intake valves and the pair of exhaust valves can be arranged to be inclined to opposite sides to each other; and a bottom surface extending orthogonal to the central axis of the piston, wherein a pressing portion is formed between the top wall and the top surface of the piston, and the top surface of the piston is provided with: a bulge portion surrounding the bowl portion; and a pair of intake side valve recesses and a pair of exhaust side valve recesses that avoid interference with the pair of intake valves and the pair of exhaust valves, wherein the compression portion includes: a cylinder head intake side flat portion and a cylinder head exhaust side flat portion which are provided on the top wall, are parallel to the bottom surface of the cylinder head, and are located at least outside the pair of intake valves and the pair of exhaust valves; a piston intake side flat portion that is provided on the top surface of the piston and faces the cylinder head intake side flat portion, and a tip end portion of which extends from an outer peripheral edge of the top surface of the piston in the radial direction to between the pair of intake side valve recesses; and a piston exhaust side flat portion that is provided on the top surface of the piston so as to face the cylinder head exhaust side flat portion, and a tip end portion of the piston extends from an outer peripheral edge of the top surface of the piston in the radial direction to between the pair of exhaust side valve recesses, the bulge portion bulging above the piston intake side flat portion and the piston exhaust side flat portion between the piston intake side flat portion and the piston exhaust side flat portion, the pair of intake side valve recesses being formed from the piston intake side flat portion to the bulge portion, the pair of exhaust side valve recesses being formed from the piston exhaust side flat portion to the bulge portion, the bowl portion being depressed from the bulge portion toward the center axis of the piston in a spherical shape, the bulge portion including: an intake side peak portion passing through the pair of intake side valve recess portions and the piston intake side flat portion; an exhaust side peak portion passing through the pair of exhaust side valve recess portions and the piston exhaust side flat portion; and a 1 st engagement peak and a 2 nd engagement peak which engage with an end of the intake-side peak and an end of the exhaust-side peak and extend along an outer peripheral edge of the top surface of the piston in the radial direction, wherein the 1 st engagement peak and the 2 nd engagement peak are located higher than the intake-side peak and the exhaust-side peak, the intake-side peak passes through the piston intake-side flat near a position where the piston intake-side flat and the pair of intake-side valve recesses intersect in the height direction of the piston, and the intake-side peak continuously increases in height as extending from the piston intake-side flat toward the 1 st engagement peak and the 2 nd engagement peak, and the exhaust-side peak passes through the piston exhaust-side flat near a position where the piston exhaust-side flat and the pair of exhaust-side valve recesses intersect in the height direction of the piston, and, the exhaust side crest portions continuously increase in height as they extend from the piston exhaust side flat portion toward the 1 st and 2 nd engagement crest portions.
Effects of the invention
As described above, according to the present invention, the valve recess, the bulge portion, and the bowl portion are provided on the top surface of the piston, so that the combustibility of the air-fuel mixture can be easily improved, and the cooling loss of the combustion gas can be easily reduced.
Drawings
Fig. 1 is a diagram showing a combustion chamber structure of an internal combustion engine according to an embodiment of the present invention, and is a plan view of a cylinder head.
Fig. 2 is a diagram showing a combustion chamber structure of an internal combustion engine according to an embodiment of the present invention, and is a diagram showing a top wall of the combustion chamber.
Fig. 3 is a sectional view taken in the direction III-III of fig. 1.
Fig. 4 is a diagram showing a combustion chamber structure of an internal combustion engine according to an embodiment of the present invention, and is a perspective view of a piston.
Fig. 5 is a diagram showing a combustion chamber structure of an internal combustion engine according to an embodiment of the present invention, and is a plan view of a piston.
Fig. 6 is a diagram showing a combustion chamber structure of an internal combustion engine according to an embodiment of the present invention, and is a front view of a piston.
Fig. 7 is a view showing the structure of a combustion chamber of an internal combustion engine according to an embodiment of the present invention, and is a view in section in the direction vii-vii in fig. 5.
Fig. 8 is a diagram showing a combustion chamber structure of an internal combustion engine according to an embodiment of the present invention, and is an enlarged view of the vicinity of an intake peak in fig. 7.
Fig. 9 is a view showing a structure of a combustion chamber of an internal combustion engine according to an embodiment of the present invention, and is a sectional view taken along direction IX-IX in fig. 5.
Fig. 10 is a diagram showing a combustion chamber structure of an internal combustion engine according to an embodiment of the present invention, and is a diagram showing a positional relationship between a spark plug and a 2 nd bowl portion when a piston is positioned at a top dead center.
Fig. 11 is a diagram showing a combustion chamber structure of an internal combustion engine according to an embodiment of the present invention, and is a diagram showing a flow of an air-fuel mixture in the combustion chamber when a piston is positioned at a top dead center.
Description of the reference numerals
An engine (internal combustion engine), 2.. a cylinder head, 2r.. a top wall, 2a.. a bottom surface (bottom surface of the cylinder head), 3.. a cylinder block, 4.. a cylinder, 5.. a piston, 5a.. a top surface (top surface of the piston), 5a.. a central axis (central axis of the piston), 5b, 5c.. an outer peripheral edge (outer peripheral edge in a radial direction of the top surface of the piston), 6.. a combustion chamber, 7A, 7b.. an intake valve, 8A, 8b.. an exhaust valve, 11, 12.. an extrusion portion, 13.. a cylinder head intake side flat portion, 14.. a cylinder head exhaust side flat portion, 15.. a piston intake side flat portion, 15a. a top end portion (top end portion of the piston intake side flat portion), 16.. a piston exhaust side flat portion, 16a.. a top end portion (top end portion of the piston side exhaust side), 17. 18.. intake side valve recess, 19, 20.. exhaust side valve recess, 21.. bulb, 22.. 1 bowl (bowl), 23.. intake side peak, 23a, 23b.. end (end of intake side peak), 24.. exhaust side peak, 24a, 24b.. end (end of exhaust side peak), 25.. 1 st joining peak, 26.. 2 nd joining peak, 29.. 2 nd bowl, 30.. spark plug.
Detailed Description
A combustion chamber structure of an internal combustion engine according to an embodiment of the present invention includes a combustion chamber formed by a cylinder block, a piston, and a cylinder head, the cylinder block having a cylinder, the piston being housed in the cylinder and being capable of reciprocating, the cylinder head being attached to the cylinder block, the cylinder head including: a ceiling wall of an inclined ridge shape, whereby the pair of intake valves and the pair of exhaust valves can be arranged to be inclined to opposite sides to each other; and a bottom surface extending orthogonally to the central axis of the piston, a pressing portion being formed between the top wall and the top surface of the piston, the top surface of the piston being provided with: a bulge portion surrounding the bowl portion; and a pair of intake side valve recesses and a pair of exhaust side valve recesses that avoid interference with the pair of intake valves and the pair of exhaust valves, wherein the compression portion has: a cylinder head intake side flat portion and a cylinder head exhaust side flat portion which are provided on the top wall, are parallel to the bottom surface of the cylinder head, and are located at least outside the pair of intake valves and the pair of exhaust valves; a piston intake side flat portion that is provided on the top surface of the piston and that faces the cylinder head intake side flat portion, and whose tip end portion extends from the outer peripheral edge of the top surface of the piston in the radial direction to between the pair of intake side valve recesses; and a piston exhaust side flat portion that is provided on the top surface of the piston and faces the cylinder head exhaust side flat portion, and whose tip end portion extends from the outer peripheral edge of the top surface of the piston in the radial direction to between the pair of exhaust side valve recesses, a bulge portion bulging above the piston intake side flat portion and the piston exhaust side flat portion between the piston intake side flat portion and the piston exhaust side flat portion, the pair of intake side valve recesses being formed from the piston intake side flat portion to the bulge portion, the pair of exhaust side valve recesses being formed from the piston exhaust side flat portion to the bulge portion, the bowl portion being recessed from the bulge portion toward the central axis of the piston in a spherical shape, the bulge portion having: an intake side peak portion passing through the pair of intake side valve recess portions and the piston intake side flat portion; an exhaust side peak portion passing through the pair of exhaust side valve recess portions and the piston exhaust side flat portion; and the 1 st and 2 nd engagement crests which engage with the end of the intake side crest and the end of the exhaust side crest and extend along the outer peripheral edge in the radial direction of the top face of the piston, the 1 st and 2 nd engagement crests being located at positions higher than the intake side crest and the exhaust side crest, the intake side crest passing through the piston intake side flat near the position where the piston intake side flat and the pair of intake side valve recesses intersect in the height direction of the piston, and the height of the intake side crest continuously increasing as extending from the piston intake side flat toward the 1 st and 2 nd engagement crests, the exhaust side crest passing through the piston exhaust side flat near the position where the piston exhaust side flat and the pair of exhaust side valve recesses intersect in the height direction of the piston, and the 1 st and 2 nd engagement crests extending from the piston exhaust side flat toward the 1 st and 2 nd engagement crests, the height of the exhaust side peak continuously increases.
Therefore, the top surface of the piston is provided with the valve recess, the bulge, and the bowl, so that the combustibility of the air-fuel mixture can be easily improved, and the cooling loss of the combustion gas can be easily reduced.
[ example 1 ]
Next, a combustion chamber structure of an internal combustion engine according to an embodiment of the present invention will be described with reference to the drawings.
Fig. 1 to 11 are diagrams showing a combustion chamber structure of an internal combustion engine according to an embodiment of the present invention.
First, the configuration is explained.
In fig. 1 and 2, an engine 1 as an internal combustion engine includes a cylinder head 2. The cylinder head 2 is formed with a pair of intake ports 2b, 2c and a pair of exhaust ports 2d, 2 e.
In fig. 3, an engine 1 includes a cylinder block 3, and a cylinder head 2 is provided at an upper portion of the cylinder block 3. A cylinder 4 is formed inside the cylinder block 3, and a piston 5 is provided inside the cylinder 4 so that the piston 5 can reciprocate.
The piston 5 is connected to an unillustrated crankshaft via an unillustrated connecting rod, and the reciprocating motion of the piston 5 is converted into the rotational motion of the crankshaft via the connecting rod.
A combustion chamber 6 is formed in the cylinder head 2 and the cylinder block 3. The combustion chamber 6 is formed of a space surrounded by an intake side ceiling wall 2f and an exhaust side ceiling wall 2g (see fig. 2) formed on the bottom surface 2a of the cylinder head 2, the inner wall (cylinder bore) of the cylinder 4, and the top surface 5A of the piston 5.
In fig. 1, a cylinder head 2 is provided with a pair of intake valves 7A, 7B and a pair of exhaust valves 8A, 8B. The intake valve 7A has an umbrella portion 7A (see fig. 2) at the tip end, and the intake port 2b is opened and closed by the umbrella portion 7A in synchronization with the rotation of an intake cam (not shown).
The intake valve 7B has a tip 7B (see fig. 2), and opens and closes the intake port 2c by the umbrella portion 7B in synchronization with rotation of an intake cam (not shown).
The exhaust valve 8A has an umbrella portion 8A (see fig. 2) at the distal end, and the exhaust port 2d is opened and closed by the umbrella portion 8A in synchronization with rotation of an exhaust cam (not shown).
The exhaust valve 8B has an umbrella portion 8B (see fig. 2) at the distal end, and the exhaust port 2e is opened and closed by the umbrella portion 8B in synchronization with rotation of an exhaust cam (not shown).
The bottom surface 2a of the cylinder head 2 has a plane extending orthogonal to the central axis 5a of the piston 5.
In fig. 3, the intake side ceiling wall 2f and the exhaust side ceiling wall 2g are inclined upward from the bottom surface 2a toward the central axis 5a of the piston 5, and the intake valves 7A and 7B and the exhaust valves 8A and 8B are provided in the cylinder head 2 so as to be inclined toward opposite sides to each other. The intake side ceiling wall 2f and the exhaust side ceiling wall 2g of the present embodiment constitute a ceiling wall 2R of a ridge (roof) type.
Squeeze (squish) portions 11, 12 are formed between the intake side ceiling wall 2f and the exhaust side ceiling wall 2g and the top surface 5A of the piston 5.
The squeezing portions 11, 12 have a cylinder head intake side flat portion 13 and a cylinder head exhaust side flat portion 14, and the cylinder head intake side flat portion 13 and the cylinder head exhaust side flat portion 14 are provided on the intake side ceiling wall 2f and the exhaust side ceiling wall 2g, are parallel to the bottom surface 2a of the cylinder head 2, and are located outside the intake valves 7A, 7B and the exhaust valves 8A, 8B.
The pressing portions 11, 12 have a piston intake side flat portion 15 and a piston exhaust side flat portion 16, and the piston intake side flat portion 15 and the piston exhaust side flat portion 16 are provided on the top surface 5A of the piston 5, and are opposed to the cylinder head intake side flat portion 13 and the cylinder head exhaust side flat portion 14.
The cylinder head intake side flat portion 13 and the piston intake side flat portion 15 are formed as parallel planes, and the cylinder head exhaust side flat portion 14 and the piston exhaust side flat portion 16 are formed as parallel planes.
In fig. 4 and 5, a pair of intake side valve recesses 17 and 18 are formed in the top surface 5A of the piston 5, and the intake side valve recesses 17 and 18 are recessed below the piston intake side flat portion 15. Fig. 5 shows the positional relationship between the umbrella portions 7a and 7b and the intake- side valve recesses 17 and 18, and the positional relationship between the umbrella portions 8a and 8b and the exhaust- side valve recesses 19 and 20.
The intake side valve recesses 17 and 18 constitute escape portions that avoid interference with the intake valves 7A and 7B when the intake valves 7A and 7B open the intake ports 2B and 2c and move below the intake side ceiling wall 2 f.
A pair of exhaust side valve recesses 19 and 20 are formed in the top surface 5A of the piston 5, and the exhaust side valve recesses 19 and 20 are recessed below the piston exhaust side flat portion 16.
The exhaust-side valve recesses 19 and 20 constitute escape portions that avoid interference with the exhaust valves 8A and 8B when the exhaust valves 8A and 8B open the exhaust ports 2d and 2e and move below the exhaust-side ceiling wall 2 g.
The piston intake side flat portion 15 has a tip end portion 15A, and the tip end portion 15A extends from the outer peripheral edge 5b of the top surface 5A of the piston 5 in the radial direction to between the intake side valve recesses 17, 18.
The piston exhaust side flat portion 16 has a tip end portion 16a, the tip end portion 16a extends from an outer peripheral edge 5c in the radial direction of the top surface 5A of the piston 5 to between the exhaust side valve recess portions 19, 20, and the outer peripheral edge 5c is located on the opposite side of the outer peripheral edge 5b in the radial direction with respect to the central axis 5A of the piston 5.
The piston 5 has a raised portion 21 on the top surface 5A. The bulging portion 21 bulges upward above the piston intake side flat portion 15 and the piston exhaust side flat portion 16 between the piston intake side flat portion 15 and the piston exhaust side flat portion 16.
A 1 st bowl 22 is formed on the top surface 5A of the piston 5 surrounded by the bulge 21, and the bottom wall of the 1 st bowl 22 is recessed in a spherical shape from the bulge 21 toward the central axis 5A of the piston 5. The bowl portion 22 of the present embodiment constitutes the bowl portion of the present invention.
In the height direction of the piston 5, the intake side valve recesses 17, 18 are formed from the piston intake side flat portion 15 to the bulge portion 21, and are inclined upward from the piston intake side flat portion 15 toward the bulge portion 21 along the inclination direction of the umbrella portions 7a, 7b.
In the height direction of the piston 5, the exhaust-side valve recesses 19 and 20 are formed from the piston exhaust-side flat portion 16 to the bulging portion 21, and are inclined upward from the piston exhaust-side flat portion 16 toward the bulging portion 21 along the inclination direction of the umbrella portions 8a and 8b.
The ridge portion 21 has: an intake side peak 23 passing through the intake side valve recesses 17, 18 and the piston intake side flat portion 15; and an exhaust side peak 24 passing through the exhaust side valve recesses 19, 20 and the piston exhaust side flat portion 16.
The ridge portion 21 has: a 1 st engaging peak 25 which engages an end 23a of the intake side peak 23 and an end 24a of the exhaust side peak 24 and extends along an outer peripheral edge 5d in the radial direction of the top surface 5A of the piston 5; and a 2 nd engaging peak 26 which engages an end 23b of the intake side peak 23 and an end 24b of the exhaust side peak 24 and extends along an outer peripheral edge 5e in the radial direction of the top surface 5A of the piston 5.
In fig. 4 and 5, the swelling portion 21 has an inclined surface 23A (see fig. 8 for details), and the inclined surface 23A is inclined from the intake side peak 23 toward the intake side valve recess 17, 18. As shown in fig. 8, the upper end of inclined surface 23A in the direction of inclination rises upward from piston intake side flat portion 15.
In fig. 4 and 5, the raised portion 21 has an inclined surface 24A, and the inclined surface 24A is inclined from the exhaust-side peak 24 toward the exhaust- side valve recess 19, 20. The upper end of the inclined surface 24A in the inclined direction rises upward from the piston exhaust side flat portion 16.
In fig. 7, the 1 st engaging peak 25 is located higher than the intake side peak 23 and the exhaust side peak 24.
In fig. 6, the 2 nd engaging peak 26 is located higher than the intake side peak 23 and the exhaust side peak 24.
In fig. 4 and 5, the intake side peak 23 passes through the piston intake side flat portion 15 in the vicinity of a position 27 where the piston intake side flat portion 15 and the intake side valve recesses 17 and 18 intersect in the height direction of the piston 5.
The position 27 where the piston intake side flat portion 15 and the intake side valve recesses 17, 18 intersect in the height direction of the piston 5 is a portion where the piston intake side flat portion 15 and the intake side valve recesses 17, 18 are continuous in the vertical direction, and is the outer peripheral end of the intake side valve recesses 17, 18.
Further, the height of the intake side peak 23 continuously increases as it extends from the piston intake side flat portion 15 toward the 1 st engagement peak 25 and the 2 nd engagement peak 26 (refer to fig. 9).
The exhaust-side peak 24 passes through the piston exhaust-side flat portion 16 in the vicinity of a position 28 where the piston exhaust-side flat portion 16 and the exhaust-side valve recesses 19, 20 intersect in the height direction of the piston 5.
The position 28 at which the piston exhaust side flat portion 16 and the exhaust side valve recesses 19, 20 intersect in the height direction of the piston 5 is a portion where the piston exhaust side flat portion 16 and the exhaust side valve recesses 19, 20 are continuous in the vertical direction, and is the outer peripheral end of the exhaust side valve recesses 19, 20.
Further, the height of the exhaust side peak 24 continuously increases as it extends from the piston exhaust side flat portion 16 toward the 1 st engagement peak 25 and the 2 nd engagement peak 26.
Accordingly, the 1 st bowl portion 22 recessed in a spherical shape from the ridge portion 21 toward the central axis 5A of the piston 5 can be formed on the top surface 5A of the piston 5.
In contrast, if the heights of the intake side ridge 23 and the exhaust side ridge 24 are continuously decreased as they extend from the piston intake side flat portion 15 and the piston exhaust side flat portion 16 toward the 1 st engagement ridge 25 and the 2 nd engagement ridge 26, respectively, the 1 st bowl portion 22, which is recessed from the bulge portion 21 toward the central axis 5A of the piston 5 in a spherical shape, cannot be formed in a wide range on the top surface 5A of the piston 5.
In fig. 2, an ignition plug 30 is provided at a center portion of a ceiling wall 2R that is a connecting portion between an intake side ceiling wall 2f and an exhaust side ceiling wall 2 g.
In fig. 4 and 5, the 2 nd bowl portion 29 is provided in the center of the 1 st bowl portion 22.
In fig. 9, the radius of curvature R1 of the 1 st bowl 22 is formed to be larger than the radius of curvature R2 of the 2 nd bowl 29, and the 2 nd bowl 29 is formed to have a radius smaller than the radius of the 1 st bowl 22 centered on the central axis 5a of the piston 5 and a spherical depth larger than that of the 1 st bowl 22.
In fig. 10, the 2 nd bowl portion 29 is formed on the top surface 5A of the piston 5 and is vertically aligned with the ignition plug 30.
The spark plug 30 receives a high-voltage current generated by an ignition coil, not shown, through the center electrode 30a, and generates a spark in a gap between the center electrode 30a and the ground electrode 30 b. Thereby, the mixture of air and fuel introduced into the combustion chamber 6 is ignited.
The distance L1 from the center of the 2 nd bowl 29 to the ignition position 30c is set to be equal to the center electrode 30aIs substantially the same distance L2 from the upper end of the firing position 30 c.
In the combustion chamber structure of the engine 1 of the present embodiment, the squish portions 11, 12 are formed between the intake side ceiling wall 2f and the exhaust side ceiling wall 2g and the top surface 5A of the piston 5. The squeezing portions 11, 12 have a cylinder head intake side flat portion 13 and a cylinder head exhaust side flat portion 14, and the cylinder head intake side flat portion 13 and the cylinder head exhaust side flat portion 14 are parallel to the bottom surface 2a of the cylinder head 2 and are provided radially outward of the top surface 5A of the piston 5 as compared with the intake valves 7A, 7B and the exhaust valves 8A, 8B.
The pressing portion 11 has a piston intake side flat portion 15, the piston intake side flat portion 15 is provided on the top surface 5A of the piston 5 and opposed to the cylinder head intake side flat portion 13, and a tip end portion 15A thereof extends from an outer peripheral edge 5b in the radial direction of the top surface 5A of the piston 5 to between the intake side valve recesses 17, 18.
The pressing portion 12 has a piston exhaust side flat portion 16, the piston exhaust side flat portion 16 is provided on the top surface 5A of the piston 5 so as to be opposed to the cylinder head exhaust side flat portion 14, and a tip end portion 16a thereof extends from an outer peripheral edge 5c in the radial direction of the top surface 5A of the piston 5 to between the exhaust side valve recesses 19, 20.
Accordingly, the air introduced from the intake ports 2b, 2c into the combustion chamber 6 can be directed toward the center axis 5a of the piston 5 by the squeezing portions 11, 12 when the piston 5 rises toward the top dead center.
Further, the squeeze portion 11 is formed by a cylinder head intake side flat portion 13 and a piston intake side flat portion 15 parallel to the bottom surface 2a of the cylinder head 2, and the squeeze portion 12 is formed by a cylinder head exhaust side flat portion 14 and a piston exhaust side flat portion 16 parallel to the bottom surface 2a of the cylinder head 2, whereby the volume of the combustion chamber 6 can be reduced. Therefore, the compression ratio can be increased without greatly increasing the height of the bulging portion 21.
Further, according to the combustion chamber structure of the engine 1 of the present embodiment, the bulging portion 21 is provided, and the bulging portion 21 bulges upward of the piston intake side flat portion 15 and the piston exhaust side flat portion 16 between the piston intake side flat portion 15 and the piston exhaust side flat portion 16.
Further, the 1 st bowl portion 22 is provided on the top surface 5A of the piston 5, and the 1 st bowl portion 22 is recessed from the ridge portion 21 toward the central axis 5A of the piston 5 in a spherical shape.
The ridge portion 21 has: an intake side peak 23 passing through the intake side valve recesses 17, 18 and the piston intake side flat portion 15; an exhaust side peak 24 passing through the exhaust side valve recesses 19, 20 and the piston exhaust side flat portion 16; a 1 st engaging peak 25 which engages an end 23a of the intake side peak 23 and an end 24a of the exhaust side peak 24 and extends along an outer peripheral edge 5d in the radial direction of the top surface 5A of the piston 5; and a 2 nd engaging peak 26 which engages an end 23b of the intake side peak 23 and an end 24b of the exhaust side peak 24 and extends along an outer peripheral edge 5e in the radial direction of the top surface 5A of the piston 5.
The 1 st engagement peak 25 and the 2 nd engagement peak 26 are located higher than the intake side peak 23 and the exhaust side peak 24.
The intake side peak 23 passes through the piston intake side flat portion 15 near a position 27 where the piston intake side flat portion 15 and the intake side valve recesses 17, 18 intersect in the height direction of the piston 5, and the height of the intake side peak 23 continuously increases as extending from the piston intake side flat portion 15 toward the 1 st engagement peak 25 and the 2 nd engagement peak 26.
The exhaust side peak 24 passes through the piston exhaust side flat 16 near a position 28 where the piston exhaust side flat 16 and the exhaust side valve recess 19, 20 intersect in the height direction of the piston 5, and the height of the exhaust side peak 24 continuously increases as it extends from the piston exhaust side flat 16 toward the 1 st engagement peak 25 and the 2 nd engagement peak 26.
Thus, the intake-side ridge 23 and the exhaust-side ridge 24 can be provided at positions distant from the central axis 5a of the piston 5 and close to the piston intake-side flat portion 15 and the piston exhaust-side flat portion 16.
Therefore, the compression ratio can be increased without greatly increasing the height of the bulge portion 21, and the 1 st bowl portion 22 can be made shallow, the installation area of the 1 st bowl portion 22 can be enlarged, and the curvature radius R1 of the 1 st bowl portion 22 can be increased.
Therefore, the overall shape of the combustion chamber 6 when the piston 5 is positioned at the top dead center can be made close to a spherical shape, and the flow of the air-fuel mixture swirling in the longitudinal direction inside the cylinder 4 can be maintained. As a result, the fuel and the air can be uniformly mixed in the combustion chamber 6, and the combustibility of the air-fuel mixture can be improved.
Fig. 11 is a diagram showing the flow of the air-fuel mixture in the combustion chamber 6 when the piston 5 is positioned at the top dead center, and the thicker the line, the larger the flow velocity of the air-fuel mixture. As is apparent from fig. 11, in the combustion chamber structure of the engine 1 of the present embodiment, as indicated by the arrow a, the flow of the air-fuel mixture swirling in the longitudinal direction inside the cylinder 4 can be maintained, which is confirmed through experiments.
In addition, according to the combustion chamber structure of the engine 1 of the present embodiment, in the height direction of the piston 5, the intake side valve recesses 17, 18 are formed from the piston intake side flat portion 15 to the bulging portion 21, and the exhaust side valve recesses 19, 20 are formed from the piston exhaust side flat portion 16 to the bulging portion 21.
Accordingly, the intake side valve recesses 17 and 18 and the 1 st bowl 22 can be connected by the low-height ridge portion 21, and the exhaust side valve recesses 19 and 20 and the 1 st bowl 22 can be connected by the low-height ridge portion 21.
Therefore, the spaces inside the intake side valve recesses 17, 18 and the exhaust side valve recesses 19, 20 and the space inside the 1 st bowl portion 22 can be smoothly communicated with each other, the air-fuel mixture entering the intake side valve recesses 17, 18 and the exhaust side valve recesses 19, 20 can be easily combusted, and the combustibility of the air-fuel mixture can be more effectively improved.
Furthermore, since the 1 st bowl portion 22 has a spherical shape with a small depth and a large surface area, the surface area of the top surface 5A of the piston 5 can be reduced as compared with a conventional combustion chamber structure in which a high-height bulge portion is disposed on the top surface of the piston and a deep bowl portion is disposed on the bulge portion. Therefore, the surface area of the combustion chamber 6 can be reduced.
As a result, the cooling loss of the engine 1 due to the thermal energy of the combustion gas released from the wall surface of the combustion chamber 6 to the outside of the engine 1 can be reduced, and the combustibility of the air-fuel mixture can be more effectively improved.
In addition, according to the combustion chamber structure of the engine 1 of the present embodiment, the ignition plug 30 is provided at the center portion of the ceiling wall 2R.
The 2 nd bowl portion 29 is provided in the center of the 1 st bowl portion 22, and the 2 nd bowl portion 29 is formed to have a radius smaller than that of the 1 st bowl portion 22 centered on the central axis 5a of the piston 5 and a spherical depth larger than that of the 1 st bowl portion 22.
Accordingly, the flow of the air-fuel mixture swirling in the longitudinal direction in the cylinder 4 can be maintained, and the flame generated by the ignition plug 30 can be made less likely to contact the 1 st bowl 22 by the 2 nd bowl 29. Therefore, not only the combustibility of the air-fuel mixture can be more effectively improved, but also the cooling loss of the engine 1 can be more effectively reduced.
Although embodiments of the present invention have been disclosed, it is apparent that modifications can be made by those skilled in the art without departing from the scope of the invention. All such modifications and equivalents are intended to be included within the scope of the appended claims.
Claims (2)
1. A combustion chamber structure of an internal combustion engine,
the combustion chamber is formed by a cylinder block having a cylinder, a piston accommodated in the cylinder and capable of reciprocating, and a cylinder head attached to the cylinder block,
the cylinder head includes: a ceiling wall of an inclined ridge shape, whereby a pair of intake valves inclined in the same direction and a pair of exhaust valves inclined in the same direction can be provided so as to be inclined to opposite sides with respect to a central axis of the piston; and a bottom surface extending orthogonally to the central axis of the piston,
a squeezing portion is formed between the top wall and the top surface of the piston,
the top surface of the piston is provided with: a bulge portion surrounding the bowl portion; and a pair of intake side valve recesses and a pair of exhaust side valve recesses that avoid interference with the pair of intake valves and the pair of exhaust valves,
the above-described combustion chamber structure of the internal combustion engine is characterized in that,
the pressing part comprises: a cylinder head intake side flat portion and a cylinder head exhaust side flat portion which are provided on the top wall, are parallel to the bottom surface of the cylinder head, and are located at least outside the pair of intake valves and the pair of exhaust valves; a piston intake side flat portion that is provided on the top surface of the piston and faces the cylinder head intake side flat portion, and a tip end portion of which extends from an outer peripheral edge of the top surface of the piston in the radial direction to between the pair of intake side valve recesses; and a piston exhaust side flat portion which is provided on the top surface of the piston so as to face the cylinder head exhaust side flat portion, and a tip end portion of which extends from an outer peripheral edge of the top surface of the piston in the radial direction to a position between the pair of exhaust side valve recesses,
the bulging portion bulges upward between the piston intake side flat portion and the piston exhaust side flat portion above the piston intake side flat portion and the piston exhaust side flat portion,
the pair of intake side valve recesses are formed from the piston intake side flat portion to the bulging portion,
the pair of exhaust side valve recesses are formed from the piston exhaust side flat portion to the bulging portion,
the bowl portion is recessed from the raised portion toward the central axis of the piston in a spherical shape,
the protruding portion includes: an intake side peak portion passing through the pair of intake side valve recess portions and the piston intake side flat portion; an exhaust side peak portion passing through the pair of exhaust side valve recess portions and the piston exhaust side flat portion; and the 1 st and 2 nd engaging ridges which engage the end portions of the intake and exhaust side ridges and extend along the outer circumferential edge of the top surface of the piston in the radial direction,
the 1 st engaging crest and the 2 nd engaging crest are located higher than the intake side crest and the exhaust side crest,
the intake side ridges pass through the piston intake side flat portion in the vicinity of positions where the piston intake side flat portion and the pair of intake side valve recesses intersect in the height direction of the piston, and the height of the intake side ridges continuously increases as they extend from the piston intake side flat portion toward the 1 st engagement ridge and the 2 nd engagement ridge,
the exhaust-side ridges pass through the piston exhaust-side flat portions near positions where the piston exhaust-side flat portions and the pair of exhaust-side valve recesses intersect in the height direction of the piston, and the exhaust-side ridges continuously increase in height as they extend from the piston exhaust-side flat portions toward the 1 st and 2 nd engaging ridges.
2. The combustion chamber structure of an internal combustion engine according to claim 1,
a spark plug is arranged at the central part of the top wall,
when the bowl part is a 1 st bowl part, a 2 nd bowl part is arranged at the center part of the 1 st bowl part, and the 2 nd bowl part and the spark plug are arranged in the vertical direction,
the 2 nd bowl portion is formed to have a radius smaller than that of the 1 st bowl portion around the central axis of the piston and a spherical depth larger than that of the 1 st bowl portion.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2017211812A JP6946944B2 (en) | 2017-11-01 | 2017-11-01 | Combustion chamber structure of internal combustion engine |
| JP2017-211812 | 2017-11-01 |
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| Publication Number | Publication Date |
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| CN109751114A CN109751114A (en) | 2019-05-14 |
| CN109751114B true CN109751114B (en) | 2021-03-16 |
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| CN201811291051.9A Active CN109751114B (en) | 2017-11-01 | 2018-10-31 | Combustion chamber structure of internal combustion engine |
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| JP (1) | JP6946944B2 (en) |
| CN (1) | CN109751114B (en) |
| DE (1) | DE102018218523B4 (en) |
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| JPS503496A (en) | 1973-05-16 | 1975-01-14 | ||
| JPH08144767A (en) * | 1994-11-25 | 1996-06-04 | Yamaha Motor Co Ltd | Combustion chamber structure of engine |
| US6725828B1 (en) | 2003-06-17 | 2004-04-27 | Ford Global Technologies, Llc | Vortex-induced stratification combustion for direct injection spark ignition engines |
| JP4757112B2 (en) * | 2006-06-26 | 2011-08-24 | 本田技研工業株式会社 | Direct fuel injection diesel engine |
| JP5003496B2 (en) | 2008-01-08 | 2012-08-15 | マツダ株式会社 | Reciprocating engine |
| US7954471B2 (en) * | 2008-07-07 | 2011-06-07 | Mazda Motor Corporation | Spark ignited internal combustion engine and manufacturing the same |
| JP5537110B2 (en) * | 2009-09-30 | 2014-07-02 | ダイハツ工業株式会社 | Internal combustion engine |
| JP6088016B1 (en) | 2015-09-18 | 2017-03-01 | 富士重工業株式会社 | piston |
| JP6088015B1 (en) * | 2015-09-18 | 2017-03-01 | 富士重工業株式会社 | Fuel injection device |
| JP7346929B2 (en) | 2019-06-20 | 2023-09-20 | ブラザー工業株式会社 | liquid discharge device |
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| DE102018218523B4 (en) | 2021-08-05 |
| FR3073005B1 (en) | 2021-12-10 |
| JP6946944B2 (en) | 2021-10-13 |
| FR3073005A1 (en) | 2019-05-03 |
| JP2019085880A (en) | 2019-06-06 |
| DE102018218523A1 (en) | 2019-05-02 |
| CN109751114A (en) | 2019-05-14 |
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