JP2580404Y2 - Internal combustion engine - Google Patents

Description

[Detailed description of the invention] A. Purpose of the invention (1) Industrial application field The invention relates to an internal combustion engine, in particular, between an upper surface of a piston slidably fitted to a cylinder and a lower surface of a cylinder head. A recess forming the ceiling surface of the formed combustion chamber is provided on the lower surface of the cylinder head so as to form a squish area at the periphery of the combustion chamber, and is mounted on the cylinder head at the center of the recess. The electrode of the ignition plug is arranged, and the first and second parallel
An intake valve port is opened on one side of the electrode, and a first exhaust valve port corresponding to the first intake valve port and a second exhaust valve port corresponding to the second intake valve port are connected to the electrode. Opened on the other side, the first and second intake valves are capable of individually opening and closing the first and second intake valve ports, and the first and second exhaust valves are capable of individually opening and closing the first and second exhaust valve ports. The present invention relates to an internal combustion engine in which a valve gear is interlocked and connected to enable swirl intake from a first intake valve port.

(2) Prior Art Conventionally, such an internal combustion engine is disclosed in, for example, Japanese Patent Laid-Open No. 64-35013.
It is already known from Japanese Patent Publication No.

(3) Problems to be Solved by the Invention In the above-described conventional device, the squish area is formed over the entire circumference of the combustion chamber, and therefore, the first intake valve port and the first intake valve which are involved in swirl generation are formed. Since a squish area is also provided in the swirl generation region between the exhaust valve ports, the intake air immediately after vigorously flowing into the combustion chamber from the first intake valve port has the squish area and the squish flow from the squish area. Therefore, there is a problem that the smooth flow is hindered, and the inflow energy of the intake air cannot be sufficiently utilized for the generation of the swirl flow, and the strong swirl formation in the combustion chamber is hindered. Also, in the above-mentioned conventional type, the intake shutter valve (open / close valve 1) provided in the intake pipe is provided.
9) By suppressing intake from the second intake valve port,
The swirl is generated in the intake air from the first intake valve port. At this time, the second intake valve that opens and closes the second intake valve port that is not involved in swirl generation also performs a valve-opening operation (lift). The swirl generated in the room lifts the second
There is a problem that the intake valve is disturbed and the formation of a strong swirl flow in the combustion chamber is hindered. As a result, there is a disadvantage that the improvement of the combustibility by the swirl intake cannot be sufficiently achieved.

The present invention has been made in view of such circumstances,
It is an object of the present invention to provide an internal combustion engine capable of generating a strong swirl intake air from a first intake valve port and improving the combustibility of an air-fuel mixture.

B. Configuration of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention sets the second intake valve with the same valve lift as the first intake valve according to the operating state of the engine. The valve operating device is configured to switch between an operation mode of opening and closing operation and an operation mode of substantially stopping the opening and closing operation of the second intake valve by limiting the valve lift amount of the second intake valve to a predetermined value or less. When the valve train restricts the valve lift of the second intake valve to a predetermined value or less to substantially stop the opening / closing operation of the second valve, the valve is sucked into the combustion chamber from the first intake valve port. A swirl is generated in the intake air, and a swirl generation region extending from the first intake valve port to the first exhaust valve port along the swirl intake direction in the combustion chamber is removed from the first exhaust valve port to the second exhaust port. From the second exhaust valve opening to the second intake valve opening up to the valve opening, The opening edge shape of the recess on the lower surface of the cylinder head is determined so that squish areas are formed in three regions from the second intake valve port to the first intake valve port.

(2) Operation According to the above configuration, the swirl generating region from the first intake valve port to the first exhaust valve port where the intake air immediately after flowing into the combustion chamber from the first intake valve port is first encountered. Since the squish area is not formed, the swirling flow of the intake air immediately after vigorously flowing into the combustion chamber is not likely to be hindered by the squish area or the squish flow from the area, and the intake energy of the intake air generates the swirl flow. To be fully utilized. Moreover, the region from the first exhaust valve opening to the second exhaust valve opening where the swirl intake air thus generated meets next, and the region from the second exhaust valve opening to the second intake valve opening. Since the squish area is present in all three regions including the region from the second intake valve port to the first intake valve port, swirl intake is efficiently performed near the center of the combustion chamber, that is, in the vicinity of the electrode of the spark plug. As a result, combustion of the air-fuel mixture can be stabilized.

Further, when the valve gear limits the valve lift amount of the second intake valve to a predetermined value or less, the opening and closing operation thereof is substantially stopped, swirl is applied to the intake air taken into the combustion chamber from the first intake valve port. Is caused. Therefore, when the swirl intake air is swirling in the combustion chamber, the opening and closing operation of the second intake valve that opens and closes the second intake valve port that is not involved in swirl generation can be maintained in a substantially non-operating state with a small valve lift amount. The lift of the second intake valve into the combustion chamber during the lift is small, and the swirling flow of the intake swirl in the combustion chamber is not obstructed by the second intake valve itself. The swirl can be moved toward the center of the combustion chamber (that is, on the side of the spark plug electrode) by utilizing the intake air leaked from the second intake valve port to the combustion chamber at the time of a small lift, thereby further stabilizing the combustion of the air-fuel mixture. Can be done.

(3) Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 to 3A show one embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a main part of an internal combustion engine, and is a sectional view taken along line II of FIG. 2, and FIG. FIG. 1 is a view taken along the line II-II of FIG. 1, FIG. 3 is a view taken along the line III-III of FIG. 1, and FIG. 3A is a view showing the shape of the squish area.

First, referring to FIGS. 1 and 2 together, a cylinder head 2 is connected to an upper surface of a cylinder block 1 and provided on the cylinder block 1 so as to constitute a main part of an engine main body in an SOHC type multi-cylinder internal combustion engine. Pistons 4 each having a circular depression 4a on the upper surface are slidably fitted to the plurality of cylinders 3, and combustion chambers 5 are formed between the upper surfaces of the pistons 4 and the cylinder head 2, respectively.

First and second intake valve ports 6 ₁ , 6 ₂ and first and second exhaust valve ports 7 ₁ , 7 ₂ are provided in the cylinder head 2 so as to open to the ceiling surface of the combustion chamber 5. , Both intake valve ports 6 ₁ ,
6 ₂ is connected to a single intake port 8 opening on one side of the cylinder head 2, and both exhaust valve ports 7 ₁ , 7 ₂ are connected to the cylinder head 2.
Connected to a single exhaust port 9 opened on the other side. First
And second intake valve ports 6 _1, 6 ₂ individually first and second intake valves V _I1 openable, V _I2 are respectively slidably in a pair of guide tube 10 disposed in the cylinder head 2 are fitted, the intake valves V _I1 between the retainer 11, 11 and the cylinder head 2 which is fixed to the upper end portions of intake valves V _I1, V _I2 projecting from the guide tube 10, V _I2 Are provided, and the intake valves V _I1 and V _I2 are urged upward, that is, in the valve closing direction.
The first and second exhaust valve port 7 _1, 7 first and the exhaust valve ₂ capable of individually opening and closing V _E1, V _E2, respectively slidable on a pair of guide tube 13 disposed in the cylinder head 2 are fitted in, the exhaust valves V _E1, V between the retainer 14, 14 and the cylinder head 2 which is fixed to an upper end portion of the exhaust valves V _E1, V _E2 projecting from the guide tube 13 Coiled valve springs 15, 15 surrounding _E2 are interposed, and the exhaust valves V _E1 , V _E2 are urged upward, that is, in the valve closing direction by the valve springs 15, 15.

A valve train 16 is connected to the first and second intake valves V _I1 and V _I2 and the first and second exhaust valves V _E1 and V _E2 .
This valve train 16 is mounted on a crankshaft (not shown)
A single camshaft 17 interlocked and linked at a reduction ratio of
First and second intake side rocker arms for converting the rotational movement of the camshaft 17 into the opening and closing movements of both intake valves V _I1 and V _I2.
18 and 19, the rotational movement of the camshaft 17 is controlled by the two exhaust valves V _E1 , V
_There are first and second exhaust side rocker arms 20 and 21 for converting the opening and closing movement of _E2 .

The camshaft 17 comprises a cylinder head 2 and holders 22, 22,... Which are respectively coupled on the cylinder head 2 on both sides of the cylinder 3 along the axis of the crankshaft.
It is rotatably supported while having a horizontal axis perpendicular to the axis of the cylinder 3. The camshaft 17 is integrally provided with an intake cam 23 and a ridge 24 adjacent to one side of the intake cam 23, and exhaust cams 25 on both sides of the intake cam 23 and the ridge 24. , 25 are provided integrally. The raised portion 24 is formed to have a substantially circular outer surface centered on the axis of the camshaft 17 so that the second intake valve V _I2 is substantially at rest in the low speed range of the engine. However, at a position corresponding to the high-order portion of the intake-side cam 23, a protrusion slightly protruding from the base circle is provided. Moreover, the width of the raised portion 24 in the direction along the axis of the camshaft 17 is set relatively small.

The first intake valve V _I1 interlocked first intake side rocker arm 18 is connected, the second intake-side rocker arm 19 disposed adjacent to the first intake-side rocker arm linkage, is connected to the second intake valve V _I2 . Thus, each intake side rocker arm 18, 19
Is swingably supported at a position above the camshaft 17 by an intake side rocker arm shaft 27 fixedly supported by the holders 22, 22 while having an axis parallel to the camshaft 17. The first and second exhaust side rocker arms 20, 21 are
The first and second exhaust valves V _E1 and V _E2 are individually linked and connected to each other, and are fixedly supported by holders 22 and 22 at a position above the cam shaft 17 in parallel with the intake side rocker arm shaft 27. And is swingably supported by the exhaust side rocker arm shaft 28.

One end of the first intake side rocker arm 18 has a camshaft
A roller 29 that slides on a suction side cam 23 provided on the cam 17 is supported by a shaft. A sliding contact portion 30 that slides on a protrusion 24 provided on the camshaft 17 is provided at one end of the second suction side rocker arm 19. It is provided with a narrow width corresponding to 24. At one end of each of the exhaust-side rocker arms 20, 21, a roller 31 slidingly contacting the exhaust-side cams 25, 25 provided on the camshaft 17 is respectively supported.

Tappet screws 32 abutting on upper ends of the first and second intake valves V _I1 and V _I2 are respectively screwed to the other ends of the first and second intake side rocker arms 18 and 19 so as to be able to advance and retreat. Each intake valve V according to the swinging motion of the side rocker arms 18 and 19
_I1 and _VI2 open and close. A tappet screw 32 that contacts the upper end of each of the exhaust valves V _E1 and V _E2 is screwed to the other end of each of the exhaust side rocker arms 20 and 21 so as to be able to advance and retreat, respectively. Each of the exhaust valves V _E1 and V _E2 opens and closes according to the operation.

The first and second intake side rocker arms 18 and 19 can be connected to each other in accordance with the operation state of the engine, in which the connected state of the two intake side rocker arms 18 and 19 and the disconnected state of the two intake side rocker arms 18 and 19 are switched. A switching mechanism 34 is provided. The connection switching mechanism 34 switches between the connection state and the connection release state by a connection piston that operates according to the action of hydraulic pressure. In the high-speed operation range of the engine,
When the two intake side rocker arms 18 and 19 are connected by 34, the two intake side rocker arms 18 and 19 are oscillated by the intake side cam 23, so that both intake valves V _I1 and V _{I2 conform to} the shape of the intake side cam 23. Opening and closing operation at the same timing and lift amount, and when the connection state of the two intake side rocker arms 18 and 19 by the connection switching mechanism 34 is released in the low speed operation range of the engine, the first intake side rocker arm 18 swings by the intake side cam 23. While the second intake side rocker arm 19 is driven, the second intake side rocker arm 19 comes into sliding contact with the raised portion 24, so that the first intake valve _VI1 normally opens and closes at the timing and lift amount according to the shape of the intake side cam 23. On the other hand, as described above, the second intake valve _VI2 corresponds to the shape of the basically circular raised portion 24, which partially protrudes slightly from the base circle corresponding to the high-order portion of the intake side cam 23. The valve lift is limited to a predetermined value or less. It was placed in substantially dormant state.

By the way, the first and second exhaust side rocker arms 20, 21
Are arranged so as to be in sliding contact with the exhaust-side cams 25, 25 of the camshaft 17 on both sides of both intake-side rocker arms 18, 19, which must be arranged adjacent to each other by providing the connection switching mechanism 34. Have been. This enables both exhaust side rocker arms 2
A relatively large space can be ensured between 0,21, and both exhaust valves V _E1 , V _E2 can be arranged with a relatively large space between them. For this reason, a plug pipe 36 for inserting an ignition plug 35 provided with an electrode 35a at the center of the ceiling surface of the combustion chamber 5 is provided between the exhaust valves V _E1 and V _{E2 and} between the exhaust rocker arms 20 and. 21 are arranged on the cylinder head 2 so as to be located between them.

Third Referring also to FIG., The intake passage 37 ₁ which is formed in the cylinder head 2 continues to the first intake valve port _61, a second
The intake passage 37 ₂ is formed in the cylinder head 2 continues to the intake valve ports 6 _2, common to the intake port 8 is formed in one side surface of the cylinder head 2, one corresponding to each cylinder 3 are communicated to, one of the intake passage 37 ₁ is sucked from the first intake valve port ₆₁ when the second intake valve V _I2 becomes substantially dormant low speed operating range of the engine into the combustion chamber 5 in order to efficiently generate swirl in the intake to be, in the first just before the intake valve ports ₆₁ are curved forming bulging inwardly so along the inner surface of the combustion chamber 5.

By the way, a recess 2a forming the ceiling surface of the combustion chamber 5 is provided on the lower surface of the cylinder head 2, and an electrode 35a of the ignition plug 35 is provided at the center of the recess 2a. the first and second intake valve ports 6 _1, 6 ₂ are parallel open at one side of the electrodes 35a, also on the other side of the electrode 35a, the first and second intake valve ports 6 _1, 6 ₂ in which the first and second exhaust valve port 7 correspond respectively _1, 7 ₂ is parallel opening.

A squish area 38 is formed between the opening edge of the recess 2a and the upper surface of the piston 4 at the top dead center. The shape of the opening edge portion of the Thus to recess 2a, the first intake valve ports 6 ₁
The first peripheral portion 2a corresponding to the inner circumference of the cylinder 3 between the first intake valve port ₆₁ along a swirl intake direction 39 toward the combustion chamber 5 up to the first exhaust valve port ₇₁ from _1, a second peripheral portion 2a ₂ that corresponds to the periphery of the circular recess 4a in the piston 4 between the first and second exhaust valve port 7 _1, 7 _2, the second exhaust valve 7 ₂
And the second between intake valve ports 6 ₂ and the third peripheral edge 2a ₃ leading to irregular between the periphery of the inner peripheral and the recess 4a of the cylinder 3, between the second and first intake valve ports 6 _1, 6 ₂ and a fourth peripheral edge portion 2a ₄ corresponding to the periphery of the recess 4a is formed so as to be continuous. Therefore squish area 38 becomes a shape shown by the shaded area in Figure 3A, formed in the swirl area of the first intake valve port ₆₁ along a swirl intake direction 39 up to the first exhaust valve port ₇₁ Sarezu, a region from the first air outlet ₇₁ up to the second exhaust valve port 7 _2, and the region from the second exhaust valve port 7 ₂ up to the second intake valve port 6 _2, the second intake valve mouth 6 ₂ first intake valve port ₆₁
Is formed in the region up to. Also among the squish area 38, the intake valve ports ₆₁ and 62 between ₂ and in the part corresponding to the space between the two exhaust-valve 7 _1, 7 ₂ indentations inner periphery of the squish area 38 of the upper surface central portion of the piston 4
It corresponds to the periphery of 4a.

Next, the operation of this embodiment will be described. When the connection between the two intake rocker arms 18 and 19 by the connection switching mechanism 34 is released in the low-speed operation range of the engine, the second intake valve V _I2 is substantially in a halt state, Only one intake valve _VI1 opens and closes. Thus the combustion chamber 5, will be air-fuel mixture from the intake port 8 is supplied via the intake passage 37 ₁ and the first intake valve port _61, so that the swirl occurs in the combustion chamber 5. Moreover intake passage 37 _1, the first just before the intake valve ports ₆₁ are curved shaped to follow the inner surface of the combustion chamber 5, an intake while rotating toward the combustion chamber 5 from the first intake valve port ₆₁ Therefore, swirl can be generated more effectively.

Although the air-fuel mixture introduced into the combustion chamber 5 from the first intake valve port ₆₁ flows combustion chamber 5 along the swirl intake direction 39, first along the first intake valve port ₆₁ in the swirl intake direction 39 1 until reaching the exhaust valve port ₇₁ has not been squish area 38 is formed, Sukyashu flow swirling flow just introduced into the combustion chamber 5 from the first intake valve port 6 ₁ disrupts its pivot Acting in the direction is avoided, and the swirl flow can be efficiently generated in the combustion chamber 5.

Moreover the first and the region from the exhaust-valve ₇₁ up to the second exhaust valve port 7 _2, the second intake valve port from the second exhaust valve port 7 ₂ The so swirl intake that is generated next encounter a region up to 6 _2, the second intake valve port 6 ₂ since each is present the squish area 38 and the area up to the first intake valve port _61, a swirl intake efficiency of the combustion chamber 5 It is possible to approach the vicinity of the center (that is, the vicinity of the electrode 35a of the ignition plug 35), thereby enabling stable combustion of the air-fuel mixture.

In particular, between the two intake valve ports 6 ₁ and 6 ₂ , and both the exhaust port 7 ₁ and
7 In between _2, since the inner periphery of the squish area 38 is formed corresponding to the periphery of 4a depression in the center part of the upper surface of the piston 4, tends to occur is swirl flow along the inner surface of the combustion chamber 5, more effective swirl Can be formed in the combustion chamber 5.

Meanwhile when the swirl intake as described above is turning flow of the combustion chamber 5, the valve operating device 16 opening and closing the second intake valve V _I2, can be a valve lift amount placed in de minimis substantially dormant Therefore, a slight overhang into the combustion chamber 5 of the second intake valve V _I2 during the lift, such that the turning flow of the intake swirl in the combustion chamber 5 is disturbed by the second intake valve V _I2 itself No fear, let alone its second intake valve V _I2
It is possible to gather the in the second intake valve port 6 ₂ from the swirl utilizing leaked air flow to the combustion chamber 5 side combustion chamber 5 the center side (i.e. the spark plug electrodes 35a side) at the time of a small lift, mixed The combustion of air can be further stabilized.

In this way, not only can a strong intake swirl be generated in the combustion chamber 5, but also the generated intake swirl can be effectively brought closer to the center of the combustion chamber 5 where the plug electrode 35 a is located. Combustion stabilization of air is achieved.

In the above embodiment, although the air intake passage 37 ₁ and curved shaped at first just before the intake valve ports _61, as shown in FIG. 4, the intake passage 37 ₁
The so substantially along the inner surface of the combustion chamber 5 over the entire length leading to the first intake valve port ₆₁ from the connecting portion between the intake port 8, the position of the second intake valve ports 6 ₂ of the intake port 8 as compared with Fig. 3 It may be arranged to be shifted to the side.

C. Effects of the Invention As described above, according to the present invention, the portion where the intake air immediately after flowing into the combustion chamber from the first intake valve port is first encountered, that is, from the first intake valve port to the first exhaust valve port. Since no squish area is formed in the swirl generation area up to this point, there is no danger that the intake swirl flow immediately after flowing vigorously into the combustion chamber will be hindered by the squish area and squish flow from the area, The inflow energy of the intake air can be fully utilized for generating the swirl flow.
Moreover, the region from the first exhaust valve opening to the second exhaust valve opening where the swirl intake air thus generated meets next, and the region from the second exhaust valve opening to the second intake valve opening. Since the squish area is present in all three regions including the region from the second intake valve port to the first intake valve port, swirl intake is efficiently performed near the center of the combustion chamber, that is, near the electrode of the ignition plug. As a result, the combustion of the air-fuel mixture can be stabilized.

In addition, the second intake valve is set to the first
An operation mode in which the opening and closing operation is performed with a valve lift equivalent to that of the intake valve, and an operation mode in which the opening and closing operation of the second intake valve is substantially stopped by limiting the valve lift of the second intake valve to a predetermined value or less. When the valve train is configured to be switchable, and when the valve train limits the valve lift of the second intake valve to a predetermined value or less, the opening and closing operation thereof is substantially stopped, the first
Since the swirl is generated in the intake air taken into the combustion chamber from the intake valve port, the second intake valve port that is not involved in swirl generation is opened and closed when the swirl intake gas is swirling in the combustion chamber. Since the opening and closing operation of the intake valve can be put into a substantially stopped state in which the valve lift is small, and the second intake valve projects little into the combustion chamber at the time of lift, the intake swirl in the combustion chamber is reduced. The swirl flow is not obstructed by the second intake valve itself. Rather, the swirl is burned by utilizing the intake flow leaked from the second intake valve port to the combustion chamber side during the small lift of the second intake valve. Since it can be brought closer to the center of the chamber (that is, to the side of the spark plug electrode), the combustion of the air-fuel mixture can be further stabilized.

As a result, not only can a strong intake swirl be generated in the combustion chamber, but also the generated intake swirl can be effectively brought closer to the center of the combustion chamber where the spark plug electrode is located. It can greatly contribute to stability.

[Brief description of the drawings]

1 to 3A show an embodiment of the present invention.
FIG. 1 is a longitudinal sectional view of an essential part of an internal combustion engine,
FIG. 2 is a sectional view taken along the line II-II in FIG. 1, FIG. 3 is a sectional view taken along the line III-III in FIG. 1, FIG. 3A is a view showing the shape of the squish area, FIG. 4 is a third view showing a modification of the intake path.
It is a bottom view corresponding to a figure. 2 ... Cylinder head, 2a ... Recess, 3 ... Cylinder,
4 piston 4a recess 5 combustion chamber 6 ₁ first intake valve port 6 ₂ second intake valve port 7 ₁ first exhaust valve port 7 ₂ ... the second exhaust valve port, 8 ...... intake port, 16 ...... valve train, 35 ...... spark plug, 35a ...... electrode, 37 ₁ ...... intake passage, 38 ...... squish area, 39 ...... swirl intake direction, V _E1 , V _E2 ... exhaust valve, V _I1 , V _I2 ... intake valve

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-176116 (JP, A) JP-A-64-35013 (JP, A) JP-A-61-244830 (JP, A) JP-A-56-163 9631 (JP, A) Japanese Utility Model 62-143035 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02B 1/00-23/10 F02B 31/00-31/02

Claims (3)

(57) [Scope of request for utility model registration] 1. A ceiling surface of a combustion chamber (5) formed between an upper surface of a piston (4) slidably fitted to a cylinder (3) and a lower surface of a cylinder head (2). A recess (2a) is provided on the lower surface of the cylinder head (2) so as to form a squish area (38) around the periphery of the combustion chamber (5), and a central portion of the recess (2a) is provided with a cylinder. electrode head spark plug to be mounted on (2) (35) (35a) is arranged, wherein the recess (2a), first and second intake valve ports in parallel to each other ₍₁ 6, 6 ₂₎ The electrode (35
while being open at one side of a), first made to correspond to the first exhaust valve port ₍₇₁₎ and the second intake valve ports which are associated to the first intake valve ports (6 ₁₎ (6 ₂₎ second exhaust valve port (7 ₂₎ is opened at the other side of the electrode (35a), first and second intake valve ports (6 _1, 6 ₂₎ individually openable first and second intake valves ( V _I1, V _I2) and the first and second exhaust valve ports (7 _1,
7 ₂ ) First and second exhaust valves (V _E1 , V
Valve gear in _E2) (16) is interlocked, is connected, in an internal combustion engine capable of swirl suction from the first intake valve port _(61), in accordance with the engine operating state, the second intake valve ( V _I2 ) is opened and closed with the same valve lift as the first intake valve (V _I1 ), and the second intake is performed by limiting the valve lift of the second intake valve (V _I2 ) to a predetermined value or less. The operation valve device (16) is configured to be able to switch to an operation mode in which the opening / closing operation of the valve (V _I2 ) is substantially stopped, and the valve operation device (16) is configured to switch the second intake valve (V _I2 ). the valve lift amount when it is substantially rested its opening and closing operations by limiting below a predetermined value, the swirl in the intake air drawn into the combustion chamber (5) in the first intake valve port (6 ₁₎ occurs allowed reaches the first intake valve port first intake valve port (6 ₁₎ (7 ₁₎ along its combustion chamber (5) swirl intake direction in the (39) Except for the swirl region up, from the first exhaust valve port ₍₇₁₎ to the second exhaust valve port (7 _2), the second exhaust valve port (7 ₂₎
Up to the second intake valve port (6 _2), and the third region of the second intake valve port (6 ₂₎ to the first intake valve port (6 ₁₎ the squish area (38) is formed from Thus, the internal combustion engine is characterized in that the shape of the opening edge of the recess (2a) is determined. Wherein the intake passage provided in the cylinder head (2) by connecting the opening to the intake port (8) and the first intake valve port ₍₆₁₎ to the side of the cylinder head (2) (37 _1), at least an internal combustion engine as in claim claim, wherein the front, characterized in that the curved shaped to follow the inner surface of the combustion chamber (5) of the first intake valve port (6 _1). Wherein said squish the intake valve ports of the area (38) (6 _1, 6 ₂₎ and between the two exhaust-valve (7 _1, 7 ₂₎ the inner periphery of a portion corresponding to between the combustion chamber ( 5. A method according to claim 1, wherein the step is formed so as to correspond to the periphery of a circular recess provided in the center of the upper surface of the piston so as to form a part of the step. Internal combustion engine.