JP3373927B2 - Side valve type internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a side valve type internal combustion engine, and more particularly, to an upper and lower side of a cylinder block having a cylinder bore. The intake and exhaust ports have valve seats, and the cylinder head, which is connected to the upper surface of the cylinder block, has a combustion chamber communicating between the intake and exhaust ports and the cylinder bore.
The present invention relates to a combustion chamber equipped with an ignition plug facing an electrode. 2. Description of the Related Art Heretofore, as a combustion chamber of such an internal combustion engine, there has been known a combustion chamber having a gentle slope formed from a top located immediately above intake and exhaust valves toward a center of a cylinder bore. I have. (See, for example, Japanese Utility Model Publication No. 54-25526). However, in the above-described combustion chamber, since the top is disposed immediately above the intake and exhaust valves, the area of the opening to the cylinder bore of the combustion chamber is sufficiently large. It is difficult to increase the compression ratio while securing intake air that flows into the combustion chamber from the intake port, because the course can be bent at an acute angle at the top, so that intake resistance is large and it is difficult to increase the charging efficiency. . The present invention has been made in view of such circumstances, and has as its object to provide the above-mentioned internal combustion engine capable of increasing the compression ratio and reducing the intake resistance. [0005] In order to achieve the above object, the present invention provides a combustion chamber having a first and / or second valve which sandwiches one of an intake valve and an exhaust valve.
A substantially triangular opening edge having a corner, a second corner sandwiching the other of them, and a third corner located near the axis of the cylinder bore, and a lower surface extending from the axis of the cylinder bore to a plane including both the axes of the intake and exhaust valves. and a top portion located near the extension line of the generatrix of the cylinder bore inner peripheral surface intersecting the perpendicular line with, the top and the
The first slope surrounded by the first and third corners, and the top and second and
A second slope surrounded by three corners, and a top and first and second corners
Formed into a substantially triangular pyramid with a third slope surrounded by
Sv maximum effective opening area of the valve seat of the intake air port, when the cross-sectional area of the combustion chamber in the plane tangent to the cylinder bore inner peripheral surface comprising said bus St, the opening area of the cylinder bore of the combustion chamber was set to Sb, formula The combustion chamber is formed so that Sv <St <Sb is satisfied, and the third corner is formed by the axis of the cylinder bore.
Is positioned so as to be offset from the line to the first slope side.
The angle of the first slope with respect to the cylinder head bottom face is 3
0 ° to 50 ° and on the bottom of the cylinder head on the second slope
It is characterized in that the angle with respect to the angle is set to 60 ° to 90 ° . An embodiment of the present invention will be described below with reference to the drawings. First, in FIG. 1 and FIG.
On the upper surface of the cylinder block 1 where the cylinder bore 2 is open, the inner ends of the intake port 3 and the exhaust port 4 are open, and a plurality of cylinder heads 5 are provided so as to cover the ports 3, 4 and the opening of the cylinder bore 2. Are joined to the upper surface of the cylinder block 1 via the gasket 7 by the bolts 6. The inner ends of the intake and exhaust ports 3 and 4 are formed by valve seats 8 and 9 buried in the cylinder block 1, and these valve seat members 8 and 9 have umbrellas of intake and exhaust valves 10 and 11. The suction and exhaust ports 3 and 4 are opened and closed by the part being separated and seated. A piston 14 that can move up and down in the cylinder bore 2 is connected to a crankshaft (not shown) via a connecting rod 15. A combustion chamber 12 is formed in the cylinder head 5 and communicates between the cylinder bore 2 and the intake and exhaust ports 3 and 4.
3 is screwed to the cylinder head 5. As shown in FIG. 2, a plane P including the axis Ab of the cylinder bore 2 and orthogonal to the axis Ac of the crankshaft.
Valve seats 8 and 9 of suction and exhaust ports 3 and 4 are arranged on both sides of ₁ . FIG. 3 is a contour diagram showing the shape of the combustion chamber 12. As is apparent from FIG. 1, the combustion chamber 12 has a generally triangular pyramid shape with rounded portions. That is, the combustion chamber 12, 1 Tsunomaru top 16 tinged taste, slope 17 _{1-17 3} bearing a three round taste extending from the top 16 downward
And a rounded triangular opening edge 18 formed at the lower end of these slopes. The top portion 16 extends from the axis Ab of the cylinder bore 2 to both the axis Ai of the intake and exhaust valves 10 and 11.
When a perpendicular line is dropped Lr to the plane P ₂ containing ae, it is disposed in the vicinity extension line of the bus Lg of second inner peripheral surface cylinder bore intersecting the perpendicular line Lr. The opening edge 18 is sandwiched the first and second corner portions 19 _1, 19 ₂ absorption, the umbrella portion of the exhaust valves 10, 11 respectively, the third corner 17 ₃ the cylinder bores 2
So as to be positioned in the vicinity of the axis Ab, they are arranged in particular from said axis Ab to slightly offset to the first inclined surface 17 ₁ side. The angle of each inclined surface 17 _{1-17 3} of the cylinder head 5 the bottom surface of the combustion chamber 12 is set at an acute angle of more than 30 °. Particularly preferably, the top 16 and the first and third corners 1
9 _1, 19 ₃ first inclined surface 17 is surrounded by the _first angle α with respect to the cylinder head 5 bottom (see FIG. 4) is relatively small,
That 30 ° is set to to 50 °, also a top 16 and a second, second inclined surface 17 is surrounded by the third corner portion 19 _2, 19 _{3 2}
(See FIG. 5) is relatively large with respect to the bottom surface of the cylinder head 5, that is , set at 60 ° to 90 °. Here, the maximum effective opening area of the valve seat 8 of the intake port 3 due to the opening of the intake valve 10 is Sv, and the bus Lg
St sectional area of the combustion chamber 12 in a plane P ₃ which is in contact with the second inner peripheral surface cylinder bore comprise, when the opening area of the cylinder bore 2 of the combustion chamber 12 was set to Sb, the combustion chamber 12 as the following expression is satisfied It is formed. Sv <St <Sb For example, Sv = 255.2 mm ² , St = 476 mm ² , S
b = 807 mm ² is set. The intake and exhaust valves 10 and 11 have their axes A
As i and Ae move toward the combustion chamber 12, the cylinder bore 2
(See FIG. 1). The spark plug 13 has its electrodes are arranged to direct the first inclined surface 17 ₁ side In the or near the top 16. An inner wall portion 12a of the combustion chamber 12 immediately below the spark plug 13 is curved into the combustion chamber 12, and has a third slope 17 ₃ surrounded by the top 16 and the first and second corners 19 ₁ and 19. The lower portion is curved toward the combustion chamber, so that the volume of the combustion chamber 12 is set as small as possible. Next, the operation of this embodiment will be described. During the intake stroke of the engine in which the intake valve 10 is opened and the piston 14 is lowered, the air-fuel mixture generated by the carburetor (not shown) passes through the intake port 3 to the combustion chamber 12. First, it goes to the top 16 of the combustion chamber 12 by inertia, and after reaching the top 16, it is sucked into the cylinder bore 2 while descending along the first and second slopes 17 ₁ and 17 _2. . At this time, the combustion chamber 12 satisfies the equation (Sv <S
t <Sb), the cross-sectional area of the intake passage from the valve seat 8 of the intake port 3 to the cylinder bore 2 increases toward the cylinder bore 2,
This reduces intake resistance and contributes to improvement of charging efficiency. [0020] The third corner 19 ₃ first inclined surface 17 from the axis Ab of the cylinder bore 2 ₁ of the opening edge 18 of the combustion chamber 12
Side of the first slope 1 with a gentle angle α
7 mixture to be induced into ₁ in their entirety the cylinder bores 2
Flow toward the tangential direction, while arising a strong swirl in the cylinder bore 2, the gas mixture to be induced into the second inclined surface 17 ₂ of the steep angle β flows into generally axially of the cylinder bore 2,
Demonstrate downward pushing force. Thus, the swirl of the air-fuel mixture in the cylinder bore 2 contributes to the uniformity of the air-fuel ratio, and the pushing force of the air-fuel mixture downward contributes to the improvement of the charging efficiency. In the next compression stroke, the combustion chamber 12 has a substantially triangular pyramid shape as described above, and since there is little wasted space, a large compression ratio can be obtained, and this is combined with an improvement in the charging efficiency. High output can be achieved. If the air-fuel mixture is ignited by the ignition plug 13 at the end of the compression stroke, the electrode of the ignition plug 13 is located at or near the top of the substantially triangular pyramid-shaped combustion chamber 12 and is generated by ignition. The flame spreads almost simultaneously to the bottom portions of the combustion chamber 12 and generates powerful combustion gas at once. In the combustion chamber 12, the first and second slopes 17 ₁ and 17 ₂ facing the cylinder bore 2 are formed so as to form acute angles α and β of 30 ° or more as described above. The gas enters into the gap between the bottom surface of the cylinder head 5 and the piston 14 by the wedge action of each slope, and effectively applies a downward force to the piston 14. In this case, if the angles α and β are less than 30 ° or more than 90 °, an effective wedge effect is not exhibited, and it is not possible to expect smooth entry of the combustion gas into the opposed gap. When the piston 14 starts to descend,
Many of the combustion gas, so that flow into the cylinder bore 2 in particular along the first inclined surface 17 ₁ of less gentle angle α resistance, swirl occurs in the cylinder bore 2. In this way, the combustion gas spreads throughout the cylinder bore 2, so that not only high combustion efficiency and high output are exhibited, but also the amount of unburned components (HC) in the exhaust gas discharged to the exhaust port 4 in the next exhaust stroke is remarkably large. Decrease. In the above embodiment, various design changes can be made without departing from the gist of the present invention. For example, the positions of the intake and exhaust valves 10, 11 may be interchanged . As described above , according to the present invention, the combustion chamber is divided into the first corner portion sandwiching one of the intake and exhaust valves, the second corner portion ₂ sandwiching the other, and the axis of the cylinder bore. It is located near the extended line of the generatrix of the inner peripheral surface of the cylinder bore, which intersects with a substantially triangular opening edge having a third corner located in the vicinity and a perpendicular line lowered from the axis of the cylinder bore to a plane including both the axes of the intake and exhaust valves. Surrounded by the top, the top and the first and third corners
A first slope, and a second slope surrounded by a top and second and third corners.
And slope, top and first, third and formed schematic triangular pyramid shape having a slope and <br/>, Sv maximum effective opening area of the valve seat of the intake air port surrounded by the second corner, wherein the bus bar When the sectional area of the combustion chamber in a plane in contact with the inner peripheral surface of the cylinder bore including St is defined as St, and the opening area of the combustion chamber to the cylinder bore is defined as Sb, the combustion chamber is formed such that the equation Sv <St <Sb is satisfied. , Intake air from valve seat of intake port to cylinder bore
Passage area increases toward the cylinder bore.
As a result, it is possible to increase the compression ratio while reducing the intake resistance, thereby achieving higher output. Further cylinders since the inclination angle with respect to the cylinder head bottom surface of the portion facing the cylinder bore of the combustion chamber surface is set at an acute angle of more than 30 °, the combustion gas in the combustion chamber in the expansion stroke by the wedge effect of the inclined surface of the chamber It effectively enters the opposing gap between the head bottom surface and the piston upper surface, spreads over the entire cylinder bore, obtains a good combustion state, and can reduce the unburned components in the exhaust gas. In particular, the third corner is the axis of the cylinder bore.
From the first slope side
The angle of the first slope with respect to the cylinder head bottom face is 3
0 ° to 50 ° and on the bottom of the cylinder head on the second slope
The angle to the third angle is set to 60 ° to 90 °.
Due to the offset arrangement of the part, the angle becomes relatively gentle.
1 The air-fuel mixture induced on the slope has a cylinder bore as a whole.
Flow in the tangential direction of the
On the second slope, which is relatively steep.
The air-fuel mixture that is guided flows in a direction substantially axial to the cylinder bore.
It exerts a downward pushing force, and thus, its cylinder bore
The swirl of the air-fuel mixture in the air contributes to uniform air-fuel ratio,
The downward force of the air-fuel mixture contributes to improving the charging efficiency
You.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional front view (a sectional view taken along line 1-1 in FIG. 2) of a side valve type internal combustion engine showing one embodiment of the present invention. FIG. 2 is a sectional view taken along line 2-2 of FIG. 1; FIG. 3 is a contour diagram showing a shape of a combustion chamber of a cylinder head. FIG. 4 is a sectional view taken along line 4-4 of FIG. 3; FIG. 5 is a sectional view taken along line 5-5 of FIG. 3; [Description of Signs] 1 ... Cylinder head 2 ... Cylinder bore 3 ... Intake port 4 ... Exhaust port 5 ... Cylinder head 8 ... valve seat 10 ... intake valve 11 ... exhaust valve 12 of the valve seat 9 ----- exhaust port of the intake port .... combustion chamber 13 .... spark plug 17 _{1-17 3-} ··· First to third slopes 18 ··· Opening edges 19 _{1 to} 19 ₃ ··· First to third corners E ··· Internal combustion engine Ab ···· Axis line of cylinder bore

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Junya Inukai 1-4-1 Chuo, Wako-shi, Saitama Pref. Honda Technical Research Institute Co., Ltd. (56) References Real Open Sho 49-146305 (JP, U) Real Open Sho 51-43705 (JP, U) Actual opening 56-41126 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02B 23/08 F02F 1/24

Claims (1)

(1) Claims: 1. A cylinder block (1) having a cylinder bore (2) is opened and closed by suction and exhaust valves (10, 11) along the circumferential direction of the cylinder bore (2) on an upper surface of the cylinder block (1). Valve seats (8, 9) for suction and exhaust ports (3, 4) are provided, and the cylinder head (5) joined to the upper surface of the cylinder block (1) has suction and exhaust ports (3, 4). ) And a cylinder bore (2), a combustion chamber (12) is formed, and an ignition plug (1) that faces an electrode to the combustion chamber (12).
In the side valve type internal combustion engine equipped with 3), the combustion chamber (12) is provided with a first corner (19 ₁ ) sandwiching one of the intake and exhaust valves (10, 11) and a second corner sandwiching the other thereof. part (19 _2), and the cylinder bores third corner portion positioned on the axis (Ab) near (2) and (19 ₃₎ the opening edge of the substantially triangular with (18), the axis of the cylinder bore (2) (Ab)
And both axes (Ai, Ae) of the intake and exhaust valves (10, 11)
Flat top portion located near the extension line of the bus (Lg) of (P ₂₎ to the down perpendicular line (Lr) and intersects the cylinder bore (2) in the peripheral surface (16), its top (16) and the first containing,
The first slope (17) surrounded by the third corners (19 ₁ , 19 ₃ )
_1), top (16) and the second, third corner portion (19 _2, 1
9 ₃ ) a second slope (17 ₂ ) surrounded by a top (16)
And a third part surrounded by the first and second corners (19 ₁ , 19 ₂ ).
Slope (17 ₃₎ and formed in the schematic triangular pyramid shape with a maximum effective aperture area of the valve seat of the intake air port (3) (8) S
v, St is the sectional area of the combustion chamber (12) in a plane (P ₃ ) including the bus (Lg) and in contact with the inner peripheral surface of the cylinder bore (2), and the opening area of the combustion chamber (12) to the cylinder bore (2). when was the Sb, to form a combustion chamber (12) as equation Sv <St <Sb is formed <br /> standing, third corner portion (19 _3), the axis of the cylinder bore (2) (a
b) so as to be offset toward the first slope (17 ₁ ).
And the cylinder head of the first slope (17 ₁ ).
(5) The angle (α) to the bottom surface is 30 ° to 50 °,
The cylinder head (5) the bottom surface of the second inclined surface (17 ₂₎
The side valve type internal combustion engine, wherein an angle (β) with respect to the internal combustion engine is set to 60 ° to 90 ° .