CN1329643C - Four-stroke engine - Google Patents

Abstract

The object of the present invention is to reduce fuel consumption by lean combustion in a four-stroke engine in which a spark plug facing the combustion chamber is mounted on a cylinder head provided with a plurality of intake ports at the opening of the combustion chamber. The spark plug (26) is installed in the cylinder at a position corresponding to the intake port (20) on one end side of the parallel direction of the plurality of intake ports (20, 21) arranged in parallel and deviated from the center of the combustion chamber (19). Cover (14), around the opening end of the air inlet (21) on the one end side to the combustion chamber (19), a guide wall (142) is arranged on the top wall (19a) of the combustion chamber (19), the guide The wall (142) guides the intake air flowing into the combustion chamber (19) from the intake port (21) on the one end side to bypass the ignition plug (26).

Description

four stroke engine

technical field

The present invention relates to a four-stroke engine in which a spark plug facing the combustion chamber is mounted on a cylinder head provided with a plurality of intake ports opening to the combustion chamber.

Background technique

Conventionally, such a four-stroke engine is known, for example, from Patent Document 1 and the like.

(Patent Document 1)

Japanese Patent Publication No. 5-71767.

In the above-mentioned four-stroke engine of the prior art, since the intake air flowing into the combustion chamber from at least one of the plurality of air inlets collides with the spark plug and disperses in the combustion chamber, the mixed gas in the combustion chamber is stirred, and it is difficult to achieve lean combustion. Possibility of big fuel bill.

Contents of the invention

The present invention is proposed in view of this situation, and the purpose is to provide a four-stroke engine capable of performing lean combustion and reducing fuel consumption.

In order to achieve the above object, the four-stroke engine of the present invention is provided with a pair of intake ports opening in the combustion chamber on the cylinder head, and a spark plug facing the aforementioned combustion chamber is installed. The intake port on one end side of the side-by-side direction of the intake port is deviated from the center of the combustion chamber and is close to the center of the combustion chamber, and the spark plug is installed on the cylinder head, and the position close to the pair of intake ports is different from that of the one end side. The position of the air inlet of the air inlet forms a separate exhaust port; around the opening end of the air inlet on the one end side to the combustion chamber, a guide wall is arranged on the top wall of the combustion chamber, and the guide wall makes the The intake air flowing into the combustion chamber from the intake port on the one end side is guided so as to bypass the spark plug. A cavity is provided at the center of the surface of the piston facing the combustion chamber, and the injection valve that directly injects fuel into the combustion chamber, a pair of intake ports, and the intake port of the two intake ports that are different from the one end side are provided. The exhaust port corresponding to the gas port and the aforementioned spark plug are arranged on the cylinder head so that the two intake ports, the exhaust port, and the spark plug surround the aforementioned injection valve, and the aforementioned injection valve that injects the fuel atomized by compressed air is The top end is arranged on the cylinder head in such a way that it protrudes into the cavity of the piston at the top dead center, and the protrusion protruding to the side of the piston is protruded from the top wall of the combustion chamber, and the aforementioned spark plug is mounted on the cylinder head so that The tip is disposed below the tip of the injection valve.

According to the structure of the present invention, the intake air flowing into the combustion chamber from one of the plurality of intake ports, that is, from the intake port on one end side, is guided by the guide wall of the ceiling wall of the combustion chamber to bypass the spark plug and flow through the combustion chamber, thereby The intake air is dispersed in the combustion chamber without colliding with the spark plug, and the air-fuel mixture in the combustion chamber is not stirred, thereby achieving lean combustion and reducing fuel consumption.

With such a structure, the injection valve and the spark plug are arranged in the center of the combustion chamber, the cavity is compacted, the stratification of the mixed gas and the compression ratio are improved, the combustion efficiency is improved, and the fuel cost can be further reduced.

Furthermore, according to such a structure, the fuel can be supplied into the combustion chamber at a finer level, and by spraying the mixed gas containing the finer fuel into the cavity of the piston, the combustion efficiency can be further improved and the fuel consumption can be reduced.

Moreover, according to such a structure, the influence of the eddy flow in the combustion chamber can be suppressed, the mixed gas can be prevented from stirring due to imbalance, and a layered state with a richer mixing ratio can be formed at the bottom of the aforementioned cavity, thereby improving the ignition performance, thereby passing through a larger Lean burn reduces fuel costs.

Description of drawings

Fig. 1 is a partial longitudinal sectional side view of the engine.

Fig. 2 is a view taken along line 2-2 in Fig. 1 with the cylinder head removed.

Fig. 3 is a cross-sectional view of line 3-3 in Fig. 2 .

Fig. 4 is a sectional view of line 4-4 in Fig. 3 .

Fig. 5 is a sectional view of line 5-5 in Fig. 4 .

Fig. 6 is an enlarged sectional view of the cylinder head along line 6-6 in Fig. 2 .

Fig. 7 is a sectional view taken along line 7-7 in Fig. 2 .

Fig. 8 is a sectional view taken along line 8-8 in Fig. 7 .

Fig. 9 is a sectional view taken along line 9-9 in Fig. 7 .

Fig. 10 is a longitudinal sectional side view of the engine along line 10-10 in Fig. 2 .

Detailed ways

The implementation of the present invention will be described below according to an embodiment of the present invention shown in the accompanying drawings.

Fig. 1～Fig. 10 shows an embodiment of the present invention, and Fig. 1 is the partial longitudinal sectional side view of engine, and Fig. 2 is the direction view of line 2-2 in Fig. 1 under the state of removing cylinder head, Fig. 3 is Figure 2 is a cross-sectional view of line 3-3, Figure 4 is a cross-sectional view of line 4-4 in Figure 3, Figure 5 is a cross-sectional view of line 5-5 in Figure 4, Figure 6 is a cylinder along line 6-6 in Figure 2 The enlarged sectional view of the cover, Fig. 7 is a sectional view of line 7-7 in Fig. 2, Fig. 8 is a sectional view of line 8-8 in Fig. 7, Fig. 9 is a sectional view of line 9-9 in Fig. 7, Fig. 10 is a sectional view along line 9-9 in Fig. A longitudinal sectional side view of the engine on line 10-10 in Fig. 2.

First, in FIG. 1 , the engine main body 11 of an overhead valve type four-stroke water-cooled single-cylinder direct injection engine is equipped with: a crankcase 12, a cylinder block 13 connected to the crankcase 12, and a The cylinder head 14 connected to the cylinder block 13, and the cylinder head cover 15 connected to the cylinder head 14 on the opposite side of the cylinder block 13, and the cylinder head 14 side is mounted on a vehicle such as a motorcycle with a slightly higher front and lower rear posture. superior.

2 to 4 at the same time, the piston 17, which is slidably embedded in the cylinder cavity 16 provided on the cylinder body 13, is connected to the crankcase 12 through a connecting rod 18 and a crank pin (not shown) to rotate freely. The supported crankshaft 10 (see FIG. 1 ) forms a combustion chamber 19 facing the top of the piston 17 between the cylinder block 13 and the cylinder head 14 .

On the cylinder head 14, one end is independently opened to the top wall 19a of the combustion chamber 19 and the other end is connected to the first and second air inlets 20, 21 on the upper side of the cylinder head 14, and one end is opened to the cylinder head 14. The top wall 19 a of the combustion chamber 19 is open to the exhaust port 22 on the lower side of the cylinder head 14 at the other end.

The opening ends of the first and second intake ports 20, 21 to the combustion chamber 19 are respectively cut off by the first and second intake valves 27, 28, and the opening ends of the exhaust port 22 to the combustion chamber 19 are closed by the exhaust valve 29. Cut off the connection. That is, on the cylinder head 14, as a whole, an odd number of intake valves 27, 28 and exhaust valves 29 are arranged so as to be capable of shutting off communication, and the first and second intake valves 27, 28 are slidably arranged respectively. Embedded and combined with the guide cylinder 30... fixed on the cylinder head 14, the retainer ring 31... and the cylinder head 14 respectively fixed on the upper ends of the two intake valves 27, 28 protruding from the guide cylinder 30... Valve springs 32... are respectively arranged between them, and the elastic force generated by these valve springs 32... exerts a tight force on the two intake valves 27, 28 in the direction of the communication valve. The exhaust valve 29 can be slidably inserted into the guide cylinder 33 fixed on the cylinder head 14, and a valve spring is provided between the retainer 34 fixed on the upper end of the exhaust valve 29 protruding from the guide cylinder 33 and the cylinder head 14. 35, the elastic force produced by the valve spring 35 imparts a tight force to the exhaust valve 29 in the direction of the communication valve.

In addition, the operation axes of the two intake valves 27, 28, that is, the axes of the two guide cylinders 30 ... are vertically arranged in parallel with the axis of the crankshaft 10 on a projected view of a virtual plane including the cylinder axis C. The axis of action of the two intake valves 27,28 and the axis of action of the exhaust valve 29, that is, the axis of the guide cylinder 33, becomes V-shaped on the projection of the aforementioned imaginary plane, and the two intake valves 27,28 and the exhaust valve 29 is arranged on the cylinder head 14 so as to be capable of disconnecting and communicating.

However, on a projected view of a plane perpendicular to the cylinder axis C, the first intake port 20 and the exhaust port 22 are arranged on both sides of the aforementioned cylinder axis C, and the second intake port 21 and the exhaust port are connected to each other. The first intake port 20 is arranged side by side with the second intake port 21 on the other line L2 substantially perpendicular to the straight line L1 of 22 on the side of the cylinder axis C. The first intake port 20 corresponding to one end side along the parallel direction of the two intake ports 20 , 21 is deviated from the center of the combustion chamber 19 , and the number of intake valves 27 , 28 is smaller. A spark plug 26 facing the combustion chamber 19 is installed on the cylinder head 14 in a position where the exhaust valve 29 is side by side.

On the combustion chamber 19, there is an axis parallel to the axis of the cylinder dimple 16, that is, the cylinder axis C. Between the aforementioned two exhaust valves 27, 28 and the exhaust valve 29, through The injector 25 directly injects the fuel, and in this embodiment, the injector 25 is arranged coaxially with the cylinder axis C on the cylinder head 14 .

That is, the exhaust port 22 and the spark plug 26 corresponding to the injector 25, a pair of intake ports 20, 21, and the second intake port 21 are connected by the two intake ports 20, 21, the exhaust port 22 and the spark plug 26. The injector 25 is arranged surrounding the cylinder head 14 .

In FIG. 5 , a guide wall 142 is arranged around the opening end of the combustion chamber 19 from the second intake port 21 on one end side of the parallel direction of the first and second intake ports 20 and 21 disposed side by side. On the top wall 19 a of the combustion chamber 19 , the guide wall 142 guides the intake air flowing into the combustion chamber 19 from the second intake port 21 to bypass the spark plug 26 located at a position corresponding to the first intake port 20 .

Referring also to FIG. 6 , the cavity 143 is disposed at the central portion of the face of the piston 17 facing the combustion chamber 19 . A protrusion 144 protruding from the piston 17 side is formed on the ceiling wall 19 a of the combustion chamber 19 , and the spark plug 26 is attached to the cylinder head 14 . Furthermore, the cavity 143 is formed to be relatively deep facing the side of the spark plug 26 .

Further referring to FIGS. 7 to 9, the first and second intake valves 27, 28 and the exhaust valve 29 are driven to cut off and communicate with each other through the valve device 38. The valve device 38 has: cams on the intake side and exhaust side 39, 40 rotating cam circumference 41; driven by the aforementioned intake side cam 39 rocking intake side first rocker arm 42; driven by the aforementioned exhaust side cam 40 rocking exhaust side first rocker arm 43; one end side is provided with the second rocker arm 44 on the intake side of a pair of pushing wrists 44a, 44b in contact with the first and second intake valves 27, 28; one end side is provided with the exhaust valve 29 The contacted push arm 45a is the second rocker arm 45 on the exhaust side; the rocking motion of the first rocker arm 42 on the intake side is transmitted to the second rocker arm 44 on the intake side, which is arranged on the first and second rocker arms on the intake side The drive rod 46 on the intake side between 42 and 44; it is arranged on the first and second rocker arms 43, 45 between the exhaust side drive rod 47.

A first valve chamber 48 is formed between the cylinder head 14 and the cylinder head cover 15, and the first valve chamber 48 connects the intake side and the exhaust side second rocker arms 44, 45, rocking pivots of the aforementioned valve device 38 to support the intake air. The intake side and exhaust side second rocker shafts 58, 59 of the intake side and exhaust side second rocker arms 44, 45 and the upper parts of the intake side and exhaust side drive rods 46, 47 are accommodated; 12. The second valve chamber 49 on the cylinder block 13 and the cylinder head 14 that accommodates the remaining part of the valve device 38 is formed on the opposite side of the cylinder axis C to the side where the aforementioned spark plug 26 is arranged, and is parallel to the cylinder axis C formed in an extended manner.

In order to lubricate the part accommodated in the first valve chamber 48 of the aforementioned valve gear 38, the oil spray hole 36 is provided on the cylinder head cover 15, and the oil for lubricating the part accommodated in the first valve chamber 48 passes through the first The second valve chamber 49 returns to the oil pan 12a (see FIG. 1 ) formed in the lower part of the crankcase 12 .

The first rocker arms 42, 43 on the intake side and the exhaust side are respectively provided with rollers 54, 55 that roll from the side of the cylinder head 14 and contact the cams 39, 40 on the intake side and the exhaust side. The intake-side and exhaust-side first rocker arms 56 , 57 arranged on parallel axes between the cylinder block 13 and the cover 50 are supported in a swingable manner. On the intake side and exhaust side first rocker arms 42, 43, the cup-shaped pressing parts 42a, 43a located on the opposite side to the above-mentioned rollers 54, 55 are opened on the side of the cylinder head 14 and provided integrally, respectively. .

In the valve device 38 , the camshaft 41 is arranged in the cylinder block 13 so as to be accommodated in the second valve chamber 49 , and the both ends of the camshaft 41 having an axis parallel to the crankshaft 10 are rotatably supported by the cylinder via ball bearings 51 , 51 . Body 13 and cover 50 connected to cylinder block 13 forming the outer side of second valve chamber 49 .

And the camshaft 41 is provided with an oil supply for supplying lubricating oil to the sliding connection between the intake side and exhaust side cams 39, 40 and the first rocker arm 42 on the intake side and the first rocker arm 43 on the exhaust side. Channel 37.

In order to reduce the power from the crankshaft 10 by 1/2 for transmission, the first driven sprocket 52, the first driving sprocket 60 (see FIG. 1 ) and the circular cam chain 53 are accommodated in the second valve chamber 49, and the first The driven sprocket 52 is connected to the camshaft 41 in a non-rotatable manner, the first drive sprocket 60 is connected to the crankshaft 10 in a non-rotatable manner, and the cam chain 53 is hung around the first drive sprocket 60 and the first driven sprocket. 52.

The intake-side and exhaust-side drive rods 46 , 47 extend between portions from the first valve chamber 48 to the second valve chamber 49 , and are arranged so that the mutual interval on the side of the cylinder head 14 becomes narrow. The spherical end of one end side of the intake side and the exhaust side drive rod 46, 47 can be movably embedded and combined with the pushing parts 42a, 43a of the first rocker arm 42, 43 on the intake side and the exhaust side, and the air intake The other end spherical ends of the side and exhaust side drive rods 46, 47 can be movably engaged with the pressure receiving portions 44c, 45b of the intake side and exhaust side second rocker arms 44, 45.

On the cylinder head 14 in the first valve chamber 48, the intake side and the exhaust side second rocker shafts 58, 59 having axes parallel to the camshaft 41 are arranged on both sides of the aforementioned injector 25, supported and fixed on On the cylinder head 14, a pair of pushing wrists divided into two parts will be provided on one end side to link and connect with the two intake valves 27, 28 by abutting against the upper ends of the first and second intake valves 27, 28. The second rocker arm 44 on the intake side of the parts 44a, 44b is swingably supported on the second rocker shaft 58 on the intake side. The exhaust-side second rocker arm 45 of the pressing arm portion 45 a linked to the valve 29 is swingably supported on the exhaust-side second rocker shaft 59 .

Moreover, with respect to the second rocker arm shaft 58 on the intake side, the cup-shaped pressure receiving portion 44c that will be opened on the side of the cylinder 13 is integrally provided on the second rocker arm shaft 58 on the intake side, on the opposite side of the two pressing arm portions 44a, 44b. The other end of the arm 44 is integrally provided on the exhaust side with a cup-shaped pressure receiving portion 45b opened on the cylinder 13 side on the side opposite to the pressing arm portion 45a with respect to the second rocker shaft 59 on the exhaust side. The second rocker arm 45 .

The other ends of the intake-side and exhaust-side second rocker arms 44, 45, that is, the pressure receiving parts 44c, 45b are arranged between one ends of the intake-side and exhaust-side second rocker shafts 58, 59, and the The intake side and exhaust side drive rods 46, 47 are connected between one end portions of the intake side and exhaust side second rocker shafts 58, 59 and the other ends of the intake side and exhaust side second rocker arms 44, 45. Linkage connection at one end.

In such a valve device 38 , corresponding to the rotation of the camshaft 41 that transmits the rotational power from the crankshaft at a reduction ratio of 1/2, the first rocker arm 42 on the intake side is rocked by the intake side cam 39 , so that the intake side The driving rod 46 moves in the direction of the axis, and correspondingly, the second rocker arm 44 on the intake side swings, so that the first and second intake valves 27 and 28 are driven to open and close, and the exhaust side cam 40 is used to exhaust the air. The first rocker arm 43 on the exhaust side swings, so that the drive rod 47 on the exhaust side moves in the axial direction, and the second rocker arm 45 on the exhaust side swings accordingly, so that the exhaust valve 29 is driven to open and close.

However, since the compressed air from the reciprocating air pump 61 that reciprocates the piston 66 in a direction parallel to the cylinder axis C is supplied to the injector 25 , it corresponds to the exhaust port 24 provided in the cylinder head 14 . On one side, the air pump 61 is arranged in the lower part of the cylinder 13 . In addition, an operating chamber 62 is formed on the cylinder block 13 in a plane perpendicular to the cylinder axis C and connected to the second valve chamber 49 in a substantially L-shape and disposed below the cylinder well 16, and the air pump 61 Below the second valve chamber 49 , a connection installation portion between the second valve chamber 49 and the operation chamber 62 is arranged.

Referring to Fig. 10 at the same time, the pump casing 63 of the air pump 61 is provided with an axis parallel to the cylinder axis C, and forms a bottomed cylindrical shape with the cylinder head 14 open at the same time, and is integrally formed on the cylinder body 13. The pump casing 63 A lid member 64 that airtightly closes the opening on the side of the cylinder head 14 is connected to the cylinder block 13 . Furthermore, the cover member 64 is connected to the pump casing 63 on the same plane as the joint surface 87 between the cylinder block 13 and the cylinder head 14 .

The piston 66 is slidably embedded and connected to the pump casing 63, and the compressed air that can generate compressed air corresponding to the volume contraction is formed between one end of the piston 66 and the cover member 64. An atmospheric pressure chamber 88 disposed on the oil pan 12a side is formed between the other end of the pump casing 63 and the closed end of the pump housing 63 .

On the other hand, a cylindrical bearing member 69 having an axis passing through the piston 66 parallel to the axis of the camshaft 41 is disposed on the operation chamber 62, and the bearing members 69 are respectively connected to the protruding parts by bolts 71 . . . A plurality of, for example, four connecting pins 70 . . . of the cylinder body 13 . And the cover 72 forming the outer side of the operation chamber 62 is connected to the cylinder body 13, and when the cover 72 is opened, the aforementioned bolts 71... can be tightened and loosened.

The pump drive shaft 73 is coaxially inserted into the aforementioned bearing member 69, the roller bearing 74 is installed between one end of the bearing member 69 and the pump drive shaft 73, and the ball bearing 75 is inserted between the other end of the bearing member 69. Install between one end and the pump drive shaft 73. That is, the pump drive shaft 73 is rotatably supported by the bearing member 69 connected to the cylinder 13 .

At a portion protruding from one end of the aforementioned bearing member 69, the power from the camshaft 41 is transmitted to the pump drive shaft through a power transmission device 89 composed of a second pump drive shaft fixed to the pump drive shaft 73. driven sprocket 78 ; second drive sprocket 79 integral with first driven sprocket 52 connected to camshaft 41 ; endless chain 80 around second driven and drive sprocket 78 , 79 .

The pump drive shaft 73 is connected to the piston 66 of the air pump 61 through a scotch yoke crank 84 which is connected to the top end of an eccentric shaft 73 a protruding from an eccentric position of one end of the pump drive shaft 73 . It is formed by a sliding stopper 68 that is slidably engaged with the piston 66 . The pump drive shaft 73 rotates with the power transmitted from the camshaft 41, and accordingly the eccentric shaft 73a rotates around the axis of the pump drive shaft 73, and the piston 66 of the air pump 61 is reciprocated in the axial direction in the pump casing 63 to increase or decrease The volume of the pump chamber 65.

The piston 66 is provided with a slide hole 67 whose axis is arranged on a plane perpendicular to the axis of the camshaft 41 along its one diameter line, and the slide stopper 68 is slidably fitted into the slide hole 67 . The eccentric shaft 73a is integrally protruded from one end of the pump drive shaft 73 .

An opening 76 for inserting one end of the pump drive shaft 73 is provided on the pump casing 63 , and on the piston 66 , an opening portion 76 is provided that allows the eccentric shaft 73 a to rotate in a direction along the axis of the slide hole 67 correspondingly with the rotation of the pump drive shaft 73 . The movement is performed so that the insertion hole 77 into which the eccentric shaft 73 a is inserted passes through the longitudinal center portion of the slide hole 67 .

In the central part between the ball bearing 75 and the roller bearing 74, through-holes 81, 82 are respectively arranged on both sides of the bearing component 69, and at the position corresponding to one through-hole 81, on the bearing component 69, integrally set The oil guide 83 guides a part of the oil falling into the operation chamber 62 between the bearing member 69 and the pump drive shaft 73 . That is, the passage 134 provided in the cylinder head 14 for guiding part of the oil accumulated in the lower portion of the first valve chamber 48 is provided in the cylinder head 14, and the passage 135 opened to the operation chamber 62 is provided through the passage 134. In the cylinder block 13 , an oil guide 83 is integrally provided on the bearing member 69 so that the oil dropped from the passage 135 is introduced into the through hole 81 . Part of the oil introduced between the bearing member 69 and the pump drive shaft 73 is used to lubricate the roller bearing 74 and the ball bearing 75, and the rest falls from the through hole 82 to the lower part of the operation chamber 62 and is stored in the operation chamber 62. The oil in the lower portion passes through the lower portion of the operating chamber 62 and returns to the oil pan 12a side from the circuit 136 provided in the cylinder 13 .

With regard to the aforementioned bearing member 69, on the opposite side of the air pump 61, a water pump 90 provided with a rotation axis coaxial with the pump drive shaft 73 is mounted on the cylinder block 13, with respect to a plane including the cylinder axis C perpendicular to the pump drive shaft 73 PL, arrange the air pump 61 and the water pump 90 at plane-symmetrical positions.

The pump casing 91 of the water pump 90 is composed of a casing main body 92 formed by integrally connecting a dish-shaped portion 92b to close the open end of the bottomed cylindrical portion 92a on the side of the pump drive shaft 73, and a pump cover 93 closing the open end of the casing main body 92. In this configuration, the pump cover 93 is connected to the cylinder 13 so as to sandwich the outer peripheral portion of the open end of the casing main body 92 with the cylinder 13 .

Both ends of the pump shaft 94 coaxial with the pump drive shaft 73 are rotatably supported on the center of the closed end of the bottomed cylindrical portion 92a and the center of the pump cover 93, and the inner magnet 96 is fixedly mounted to the pump. The shaft 94 rotates integrally, and is inserted into the rotor 95 inside the bottomed cylindrical portion 92a. On the other hand, a rotating member 97 provided with a cylindrical portion 97a coaxially surrounding the bottomed cylindrical portion 92a of the aforementioned case main body 92 is fixed to the other end of the pump drive shaft 73 protruding from the other end of the bearing member 69. , the outer magnet 98 is fixedly installed on the inner surface of the aforementioned cylindrical portion 97a. Accordingly, the rotating member 97 rotates with the pump drive shaft 73 , and accordingly the rotor 95 rotates with the pump shaft 94 .

However, since the vortex chamber 99 is formed between the casing main body 92 and the pump cover 93 , the turbine 100 housed in the vortex chamber 99 is installed on the rotor 95 .

The pump cover 93 is provided with a plurality of suction ports 101 . Further, the cooling water sprayed from the water pump 90 is supplied to the head side water jacket 103 provided in the cylinder head 14 through the block side water jacket 102 provided in the cylinder block 13 and the cylinder head side water jacket 102, and the cooling water from the cylinder The cooling water discharged from the cover side water jacket 103 is introduced into a water tank not shown in the figure and returns to the water tank etc. according to the state of the suction port 101 . . . The thermostat case 105 is integrally formed on the pump cover 93 of the aforementioned water pump 90 .

An oil introduction hole 85 is provided on the upper side wall of the pump housing 63 of the air pump 61 for introducing a part of the oil flowing through the second valve chamber 49 into the pump housing 63 for lubrication, and flows through the second valve chamber 49 . However, due to the rotation in the second valve chamber 49, the intake-side cam 39 and the exhaust-side cam 40 of the camshaft 41 lift up a part of the oil flowing through the second valve chamber 49, and at the same time cause the oil to flow through the second valve chamber 49 due to the centrifugal force. The relative positions of the camshaft 41 and the oil introduction hole 85 are set so that the separated oil droplets are introduced into the oil introduction hole 85 , or a part of the oil supplied from the oil supply passage 37 is separated and scattered by centrifugal force.

The portion of the second valve chamber 49 corresponding to the valve gear 38 has a larger width than the other portions, so that the portion of the camshaft 41 corresponding to the intake cam 39 and the exhaust cam 40 is surrounded in a substantially semicircular shape. The protruding wall 86 of the second valve chamber 49 is opposed to the oil flow direction 137 in the second valve chamber 49, and is integrally protruded on the cylinder body 13. The oil introduction hole 85 of the aforementioned air pump 61 is arranged on the aforementioned protrusion along the oil flow direction 137. Just upstream of the wall 86. That is, the function of the protruding wall 86 is to introduce the oil flowing through the second valve chamber 49 into the oil introduction hole 85 .

Moreover, the oil introduction hole 85 opens to the inner peripheral surface of the pump casing 63 on the side closer to the air pressure chamber 88 than the piston ring 138 which is mounted and fixed on the outer periphery of the piston 66 and is slidably connected to the inner periphery of the pump casing 63 . Above, regardless of the axial movement of the piston 66, the oil introduction hole 85 always communicates with one end of the sliding hole 67 provided on the piston 66. On the outer circumference of the piston 66, a pair of grooves 139 are provided between the end of the piston 66 on the side of the air pressure chamber 88 and the two ends of the sliding hole 67, and the oil introduced into the pump casing 63 from the oil introduction hole 85 is provided. A part of it is used for lubrication between the piston 66 and the pump casing 63, and the rest flows into the side of the air pressure chamber 88 through the groove 139 . . . Moreover, the aforementioned groove 139 . . . can also prevent the sliding block 68 in the scotch yoke crank 84 from producing suction due to the oil overflowing in the sliding hole 67 .

The oil that has flowed into the air pressure chamber 88 flows from the opening 76 to the operating chamber 62 side, and then flows from the circuit 136 to the oil pan 12a.

Pay particular attention to FIG. 9 , the injector 25 is the first injection valve 107 installed on the cylinder head cover 15 to inject fuel and the second injection valve 108 installed on the cylinder head 14 to inject fuel directly into the combustion chamber 19 following the compressed air. Connected coaxially, the second injection valve 108 is provided with a nozzle 108 a protruding into the combustion chamber 19 .

The insertion coupling hole 109 for fitting and coupling the nozzle 108a in an airtight manner, and the insertion cylinder 110 coaxially connected to the insertion coupling hole 109 having an inner diameter larger than that of the insertion coupling hole 109 are provided coaxially with the cylinder axis C. In the cylinder head 14, insert it into the insertion cylinder 110 from the side of the cylinder head cover 15 until the second injection valve 108 is fitted into the fitting hole 109 airtightly with the nozzle 108a of the second injection valve 108 abutting against it via the wave spring washer 123. An annular stepped portion 111 is formed between the insertion coupling hole 109 and the insertion cylinder 110 .

Before abutting against the stepped part 111, under the state of inserting the insertion cylinder 110, the top end of the second injection valve 108, that is, the nozzle 108a protrudes into the cavity 143 of the piston 17 at the top dead center, and the top end of the spark plug 26 acts as the piston 17. When it is at the top dead center, it is located below the nozzle 108 a in the cavity 143 .

The wire connection part 108b with the second injection valve 108 at its rear is arranged on the cutout 110a provided at the rear end of the insertion cylinder 110, and outside the insertion cylinder 110, a pair of wires 112 .. .Through the metal hole 113 sandwiched between the joint surfaces of the cylinder head 14 and the cylinder head cover 15, and pull it to the outside.

On the other hand, the first injection valve 107 is integrally formed on the cylinder head cover 15 to fit and hold it, and at the same time, the second injection valve 108 is also used as a positioning part for positioning and clamping between the cylinder head 14 and the cylinder head 14. The functioning cylindrical injector housing 114 brings the top end of the injector housing 114 into contact with the rear end of the second injection valve 108 when the cylinder head cover 15 is connected to the cylinder head 14 . A clamping plate 115 for clamping the rear end portion of the first injection valve 107 with the injector housing 114 is connected to the rear end of the injector housing 114 .

The first injection valve 107 is provided with a wiring connector 107a at its rear, and the rear end of the first injection valve 107 is clamped by the injector case 114 and the clamping plate 115, and the first injection valve 107 is attached to the cylinder. In the case of the head cover 15 , the wiring connector 107 a is disposed so as to face the outside of the cylinder head cover 15 .

Between the injector housing 114 and the first injection valve 107, an annular combustion chamber 116 communicating with the inside of the first injection valve 107 is formed, and a pair of sealing members 117, 118 sandwiching the fuel chamber 116 from both sides are interposed. Installed between the first injection valve 107 and the injector case 114 .

Further, a fuel supply passage 119 communicating with the combustion chamber 116 is directly provided in the cylinder head cover 15 , and a pipe 120 for introducing fuel from a fuel supply source (not shown) is connected to the fuel supply passage 119 via a joint 121 .

Between the top end portion of the first injection valve 107 and the rear end portion of the second injection valve 108, an annular air chamber 122 communicating with the inside of the second injection valve 108 is formed in the injector housing 114. Compressed air from 61 is supplied to the air chamber 122.

2 and FIG. 10 , the cover member 64 of the air pump 61 is provided with a suction pipe 124 that connects a pipe that introduces air from an air cleaner (not shown). A pilot valve (not shown) is connected to the pump chamber 65 .

The poppet valve 125 that opens in accordance with the increase in the pressure of the pump chamber 65 is built in the cover member 64, and the compressed air discharged from the air pump 61 is supplied to the air chamber 122 through the poppet valve 125 and the compressed air supply passage 126. .

The compressed air supply passage 126 is composed of: a pipe member 127 connected to the aforementioned poppet valve 125, one end of which is connected to the cover member 64, and the other end is connected to the cylinder head 14; and communicating with the channel 128 and at the same time communicating with the air chamber 122, which is formed by the channel 129 directly arranged on the cylinder head cover 15.

And, the channel 128 that is directly arranged on the cylinder head 14 is arranged on the side opposite to the two drive rods 46, 47 side where the valve device 38 is arranged, that is, on the intake side and the exhaust side that are arranged in the first valve chamber 48. The other end sides of the two rocker shafts 58 and 59 are provided on the cylinder head 14 . A part of the passage 128 passes through the vicinity of the exhaust port 24, and in particular, the cylinder head water jacket 103 is disposed between the exhaust port 24 and the cylinder block 13 near the exhaust port 24. 128 sets the exhaust port 24 to pass through the opposite side of the aforementioned head-side water jacket 103 .

The two ends of the cylindrical positioning pin 130 straddling the joint surface of the cylinder head 14 and the cylinder head cover 15 are inserted into the cylinder head 14 and the cylinder head cover 15 to form a part of the compressed air passage 126, which is directly arranged on the cylinder head 14 and the cylinder head cover 15. The passages 128 , 129 of the cylinder head cover 15 are communicated through the aforementioned positioning pin 130 . And the O-ring 133 surrounding the positioning pin 130 is clamped at the joint surface of the cylinder head 14 and the cylinder head cover 15 .

An orifice 131 is formed in the positioning pin 130 , and a relief valve 132 connected to the aforementioned passage 128 on the upstream side of the orifice 131 is mounted on the cylinder head 14 .

Next, the function of this embodiment will be described. Since the first and second intake valves 27, 28 and exhaust valve 29 are projected on an imaginary plane containing the cylinder axis C with the action axes of these valves 27, 28, 29 It is disposed on the cylinder head 14 so as to be open and close in a V-shaped arrangement, and is provided with a second injection valve 108 parallel to the axis C of the cylinder to inject fuel directly into the combustion chamber 19, The cylinder head 14 is installed between the gas valves 27, 28 and the valve gas valve 29, so the fuel injected by the second injection valve 108 can be concentrated near the center of the combustion chamber 19, and lean combustion can be realized to reduce fuel consumption. Furthermore, since the second injection valve 108 can directly inject the fuel together with the compressed air into the combustion chamber 19, the fuel is injected into the combustion chamber in a more finely divided manner, and the combustibility can be improved.

As a whole, an odd number of three intake valves 27, 28 and exhaust valve 29 are arranged on the cylinder head 24, and a spark plug 26 is attached to the cylinder head 14 in parallel with the exhaust valve 29, which is a valve with a smaller number. Therefore, by effectively using the space generated around the exhaust valve 29 to arrange the spark plug 26, the degree of freedom in the arrangement of the spark plug 26 can be increased, and because the spark plug 26 can be placed close to the second injection valve 108, in addition, the injection from the second injection valve 108 can be used. Fuel spray from the pump 108 is concentrated near the center of the combustion chamber 19, thereby enabling further reduction in fuel consumption through stratified rarefaction.

Further, the spark plug 26 is attached to the cylinder head 14 at a position offset from the center of the combustion chamber 19 while corresponding to the first intake port 21 which is one end side in the parallel direction of the first and second intake ports 20 and 21 arranged in parallel. , around the opening end of the first air inlet 21 to the combustion chamber 19, a guide wall 142 is arranged on the top wall 19a of the combustion chamber 19, and the guide wall 142 makes the intake air flowing into the combustion chamber 19 from the first air inlet 21 The gas is guided in a detour through the spark plug 26 .

Therefore, the intake air flowing into the combustion chamber 19 from the first air inlet 21 is guided by the guide wall 142 of the top wall 19a of the combustion chamber 19, detoured to the spark plug 26 and flows through the combustion chamber 19, without colliding with the spark plug 26. On the other hand, dispersing the intake air in the combustion chamber 19 does not stir the air-fuel mixture in the combustion chamber 19, so that lean combustion can be realized, and the fuel cost can be further reduced.

Since the cavity 143 is provided at the central portion of the face of the piston 17 facing the combustion chamber 19, the second injection valve 108, a pair of intake ports 20, 21, and a pair of intake ports 20, 21 that directly inject fuel into the combustion chamber 19, corresponding to the second intake air The exhaust port 22 of the port 21, and the spark plug 26 are disposed on the cylinder head 14 so that the second injection valve 108 is surrounded by the two intake ports 20, 21, the exhaust port 22, and the spark plug 26. Therefore, through the combustion chamber 19 The second injection valve 108 and the spark plug 26 are arranged in the center of the piston 17 to realize the compactness of the cavity 143 of the piston 17, improve the stratification of the mixed gas and increase the compression ratio, thereby improving the combustion efficiency and reducing the fuel cost.

Since the injector 25 including the second injection valve 108 is arranged on the cylinder axis C, the first intake port 20 and the exhaust port 22 are arranged on the injector 25 on a projection view of a plane perpendicular to the cylinder axis C. At the same time, on another straight line L2 approximately perpendicular to the straight line L1 connecting the second air inlet 21 and the air outlet 22, the first air inlet 20 is arranged on one side of the injector 25. Therefore, by Disposing the injector 25 in the central part of the combustion chamber 19 can eliminate the deviation of the flame propagation distance in the combustion chamber 19 and improve the combustion efficiency. Since the first and second air inlets 20 and 21 are arranged, the air filling efficiency can be improved. The suction loss is reduced, and the spark plug 26 can be easily arranged to avoid the interference of two intake valves 27, 28 and an exhaust valve 29, and the spark plug 26 can be arranged close to the injector 25, thereby improving combustion efficiency.

Since the top end of the nozzle 108a provided with the second injection valve 108 protrudes into the cavity 143 of the piston 17 at the top dead center, the combustion efficiency is further improved by injecting the mixed gas containing the miniaturized fuel into the cavity 143, and further Reduced fuel costs.

Since the protruding portion 144 protruding from the piston 17 side is protruded from the ceiling wall 19a of the combustion chamber 19, the tip protruding from the protruding portion 144 toward the combustion chamber 19 is arranged below the tip of the second injection valve 108, that is, the tip of the nozzle 108a. The spark plug 26 is mounted on the cylinder head 14 in a stable manner. Therefore, the structure in which the top of the spark plug 26 is arranged below the second injection valve 108 in the cavity 143 can suppress and reduce the influence of the eddy flow in the combustion chamber 19 and prevent the stirring caused by the imbalance of the mixed gas. A layered state with a high mixing ratio can be formed to improve ignition performance and further reduce fuel consumption through lean combustion. Moreover, the cavity 143 becomes deeper toward the side of the spark plug 26, so that a richer mixture gas exists on the side of the spark plug 26, and the ignition performance can be further improved.

The second rocker arm 44, 45 on the intake side and the exhaust side is arranged between the intake valve 27, 28 and the exhaust valve 29, with one end linked with the intake valve 27, 28 and the exhaust valve 29, respectively. The ground rocker is pivotally supported on the intake side and the exhaust side second rocker shafts 58, 59 fixed to the cylinder head 14, and is arranged on a pair of intake sides at positions corresponding to one ends of the two rocker shafts 58, 59. and the exhaust-side driving levers 46, 47 are connected in linkage with the other ends of the intake-side and exhaust-side second rocker arms 44, 45 respectively, so only the valves of the intake valves 27, 28 and exhaust valves 29 will be driven. In the device 38 , the second rocker arms 44 , 45 on the intake side and the exhaust side and the second rocker shafts 58 , 59 on the intake side and the exhaust side are arranged on the cylinder head 14 , so that the miniaturization of the cylinder head 14 can be realized.

The intake-side and exhaust-side drive rods 46 and 47 are driven by the rotation of the camshaft 41 arranged in the cylinder block 13 on one axial side of the intake-side and exhaust-side second rocker shafts 58 and 59 . , move in the axial direction, reduce the mutual interval of the cylinder head 14 side to arrange, at the same time between the intake side and exhaust side second rocker shaft 58, 59 and the intake side and exhaust side second rocker arm The other ends of 44, 45 are connected in linkage, so the interval between the second rocker shafts 58, 59 on the intake side and the exhaust side can be set narrower, along the second rocker shaft on the intake side and the exhaust side The cylinder head 14 in the direction in which the axes of the rocker shafts 58 and 59 are connected can be downsized.

The aforementioned spark plug 26, which relates to the injector 25 including the aforementioned second injection valve 108, is mounted on the cylinder head 14 on the side opposite to the intake side and exhaust side drive rods 46, 47. Since the spark plug 26 is thus arranged, by configuring the intake Side and exhaust side second rocker arms 44, 45, and the linkage connection parts of intake side and exhaust side drive rods 46, 47, the spark plug 26 is arranged to avoid the part with less free space, and the spark plug 26 is enlarged. Moreover, since the ignition plug 26 can be placed close to the second injection valve 108 and the fuel spray from the second injection valve 108 can be concentrated near the center of the combustion chamber 19, fuel consumption can be further reduced by lean combustion.

Between the cylinder head 14 and the cylinder head cover 15 constituting a part of the engine main body 11, a first valve chamber 48 for accommodating and disposing a part of the valve device 38 is formed. On the cover 14, there is formed a second valve chamber 49 that returns the oil that lubricates the portion accommodated in the first valve chamber 48 of the valve gear 38 to the oil pan 12a formed at the lower portion of the crankcase 12, and is placed in the cylinder pocket 16. Laterally, it extends parallel to the cylinder axis C. And on the pump casing 63 of the air pump 61 that is arranged below the second valve chamber 49, it is provided to communicate with the second valve chamber 49 in order to introduce a part of the oil flowing through the second valve chamber 49 into the cylinder well as lubricating. The oil in the socket is introduced into the hole 85 .

Therefore, a part of the oil returned to the oil pan 12a after lubricating a part of the valve gear 38 can be reliably introduced into the oil introduction hole 85 of the air pump 61, and the lubricating function of the air pump 61 can be reliably exerted with a simple structure.

Since the pump casing 63 is integrally formed on the cylinder block 13 which is smaller in shape compared with the cylinder head 14 and the crankcase 12, the number of parts is reduced, and the overall miniaturization of the engine can be realized. The second valve chamber 49 and the oil introduction hole 85 The communication is easy, and the structure for supplying oil to the air pump 61 is simplified.

On the second valve chamber 49, the first passive sprocket 52, the first driving sprocket 60 and the cam chain 53 for transmitting the power from the crankshaft 10 to the camshaft 41 of the valve device 38 are accommodated, and the first passive sprocket 53 will be accommodated. The sprocket 52, the first drive sprocket 60, and the second valve chamber 49 of the cam chain 53 are used as oil return passages, so that the engine can be miniaturized and the structure for supplying oil to the air pump 61 can be simplified.

The camshaft 41 is housed and arranged in the second valve chamber 49, and the oil droplets separated by centrifugal force are introduced into the side of the oil introduction hole 85 as the camshaft 41 rotates, and the cam 41 and the oil introduction hole are set. 85, so that the cam 41 is well lubricated by the oil flowing through the second valve chamber 49, and at the same time, the scattered oil droplets are effectively introduced into the air pump 61 by the rotation of the camshaft 41, and the air pump 1 The lubrication has been greatly improved.

Between the pump drive shaft 73 connected to the air pump 61 and the camshaft 41, a power transmission device 89 for transmitting the power of the camshaft 41 to the pump drive shaft 73 is provided, and the camshaft 41 for driving the air pump 61 is placed close to the air pump 61. , the structure of the power transmission device 89 is simplified, and the miniaturization of the engine is realized.

Moreover, the camshaft 41 is also arranged on the smaller cylinder block 13, which can contribute more to the miniaturization of the engine, and the power transmission device 89 that transmits the power from the camshaft 41 to the air pump 61 can be compact in structure, At the same time, the degree of freedom in setting the gear ratio of the air pump 61 is increased. In addition, since the power transmission device 89 is configured to transmit power using the endless chain 80, it is possible to prevent the cylinder block 13 from being enlarged and reduce the number of parts regardless of the distance between the camshaft 41 and the pump drive shaft 73.

The protruding wall 36 opposite to the oil flow direction 137 in the second valve chamber 49 is protruded on the cylinder body 13, and the oil in the lower part of the second valve chamber 49 is introduced into the oil introduction hole 85, and the oil is effectively transferred through the protruding wall 86. The introduction of the oil introduction hole 85 can further improve the lubrication of the air pump 61 .

Since the air pump 61 constitutes a reciprocating structure, higher air pressure can be obtained. The pump drive shaft 73, which transmits power from the camshaft 41 to reciprocate the piston 66 in a direction parallel to the cylinder axis C, is connected to the piston 66 through a scotch yoke crank 84, so that the operating axis of the air pump 61 and The cylinder axes C are parallel, and the scotch yoke crank 84 is adopted, which eliminates the need for connecting rods, and enables miniaturization of the engine.

The air pump 61 is composed of a pump chamber 65 arranged on the side of the cylinder head 14 which generates compressed air according to volumetric contraction, and a piston 66 whose both ends face an air pressure chamber 88 arranged on the side of the oil pan 12a through the oil pan 12a. , slidably embedded in the pump housing 63, where the piston ring 138, which is fixed on the outer circumference of the piston 66 and slidingly connected to the inner circumference of the pump housing 63, is close to the side of the air pressure chamber 88, and the oil introduction hole 85 is opened to the pump. On the inner circumference of the housing 63, the oil that completes the lubrication in the air pump 61 is smoothly discharged from the air pressure chamber 88 to the oil pan 12a side by the suction action of the piston 66, thereby improving the operating efficiency and lubrication of the air pump 61.

The pump casing 63 of the air pump 61 is made into a bottomed cylindrical shape with the cylinder head 14 side open, and is integrally formed on the cylinder body 13, and the cover member 64 that airtightly closes the opening of the cylinder head 14 side of the pump casing 63 is placed The cylinder 13 and the cylinder head 14 are joined to the pump housing 63 on the same plane as the joint surface 87 , so that the man-hours for processing the cylinder 13 can be reduced.

The air pump 61 and the water pump 90 connected to both ends of the pump drive shaft 73 are arranged at positions symmetrical to the plane PL perpendicular to the pump drive shaft 73 including the cylinder axis C. The pump drive shaft 73 drives the water pump 90, which can reduce the number of parts and reduce the weight, and can reduce the cost by simplifying processing and assembly. Furthermore, it is possible to control the protrusion of the water pump 90 from the cylinder, so that an increase in the size of the cylinder 13 as a whole can be avoided.

Moreover, the water pump 90 can be arranged near the cylinder body 13 and the cylinder head 14 that should be water-cooled, shorten the water pipe, avoid the complication of the pipeline and reduce the pressure loss in the pipe.

In addition, since the injector 25 that directly injects fuel into the combustion chamber 19 together with the compressed air obtained by the air pump 61 is arranged on the cylinder head 14, the air pump 61 is not arranged on the cylinder head 14, so the freedom of arrangement is increased. To achieve downsizing of the engine, the injector 25 or its piping can be arranged on the cylinder head 14. In particular, the pump chamber 65 of the air pump 61 is arranged on the side of the cylinder head 14, and the distance between the pump chamber 65 and the injector 25 is relatively shortened, so that the compressed air supply passage 126 including the compressed air supply passage 126 for introducing compressed air from the air pump 61 into the injector 25 is avoided. The complexity of the pipeline structure can reduce the pressure loss of the aforementioned pipeline structure.

A part of the aforementioned compressed air supply passage 126 passes near the exhaust port 24, so the compressed air flowing through the compressed air supply passage 126 can be heated by the exhaust heat of the exhaust gas flowing through the exhaust port 24, thereby increasing the pressure of the compressed air. The volume increases the efficiency of the pump.

And, in the vicinity of the exhaust port 24, a part of the cylinder head side water jacket 103 is disposed between the exhaust port 24 and the cylinder block 13, while the passage 128 constituting a part of the aforementioned compressed air supply passage 126 is connected to the exhaust port. The port 24 is arranged on the opposite side of the cylinder head water jacket 103, so that the influence of the cooling caused by the cylinder head water jacket 103 and the compressed air flowing through the compressed air supply passage 126 can be avoided as much as possible, even for a water-cooled engine. High pump efficiency can be maintained.

By disposing the air pump 61 at the lower portion of the cylinder block 13 on the side corresponding to the exhaust port 24 , the air pump 61 can be disposed in an engine arrangement space including an exhaust pipe connected to the exhaust port 24 .

However, the injector 25 is coaxial with the first injection valve 107 that injects fuel and is installed on the cylinder head cover 15 and the second injection valve 108 that injects fuel directly into the combustion chamber 19 along with the compressed air and that is installed on the cylinder head 14. When the fuel injection is carried out by air assist, it is only necessary to install the first and second injection valves 107, 108 on the cylinder head cover 15 and the cylinder head 14 in sequence, so the installation work is not complicated and can reduce number of parts. And, as long as the space for installing the second injection valve 108 on the cylinder head 14 is sufficient, compared with installing the valve body with two injection valves on the cylinder head, the space to be secured on the cylinder head 14 can be reduced. The installation space contributes to miniaturization of the cylinder head 14 .

In the injector 25, the first injection valve 107 is fitted and held by the injector case 114, and the injector case 114 is integrally formed on the cylinder head cover 15. Therefore, there is no need to dispose parts constituting the injector case 114 around the cylinder head 14. Components can reduce the number of parts, while avoiding the enlargement of the engine and the complexity of the structure around the engine.

The second injection valve 108 is inserted into the cylinder head 14 while being sandwiched between the top end of the injector housing 114 and the cylinder head 14, so the second injection valve 108 is inserted into the cylinder head 14 from the cylinder head cover 15 side, and only the cylinder head cover 15 is combined with the cylinder head 14, the second injection valve 108 can be positioned relative to the cylinder head 14, the operation of installing the second injection valve 108 to the cylinder head 14 becomes easy, and the installation workability can be improved.

The first injection valve 107 is externally installed on the cylinder head cover 15 so that the wiring connector 107a faces the cylinder head cover 15, and the wire 112 connected to the second injection valve 108 is sandwiched between the cylinder head 14 and the cylinder head cover. The metal hole 113 between 15 is penetrated and pulled to the outside. Therefore, the second injection valve 108 is installed on the cylinder head 14, and at the same time, the wire 112 extending from the second injection valve 108 is inserted into the metal hole 113. The cylinder head cover 15 is connected to the cylinder head 14 under the state, and then by installing the first injection valve 107 to the cylinder head cover 15, the installation including wiring to the two injection valves 107, 108 can be completed, which further improves the installability. .

Between the first and second injection valves 107 and 108 in the injector housing 114 is formed an air chamber 122 for storing the compressed air introduced into the second injection valve 108 , and is used to introduce the compressed air into the compressed air of the second injection valve 108 . A part of the air supply structure is also used for the injector case 114 .

The fuel supply passage 119 and a part of the compressed air supply passage 126 , that is, the passage 129 , which respectively supply fuel and compressed air to the injector housing 114 , are directly provided on the cylinder head cover 15 , so that it is not necessary to arrange the injector housing 114 around the injector housing 114 to inject air into the injector housing 114 . The casing 114 provides pipelines for fuel and compressed air, etc., and can also reduce the number of parts, while avoiding the enlargement of the engine and the complexity of the structure around the engine.

A part of the compressed air supply passage 126, that is, the passage 128, is provided on the cylinder head 14 on the other end side of the second rocker shaft 58, 59 on the intake side and the exhaust side, avoiding the valve device 38, and supplying compressed air. A part of the passage 126 is provided in the cylinder head 14 so that an increase in the size of the cylinder head 14 can be avoided.

A camshaft 41 constituting a part of the valve device 38 is arranged on the cylinder block 13 so as to avoid the space between the cylinder head 14 and the cylinder head cover 15. The valve device 38 drives the first intake valve 27 and the second valve arranged on the cylinder head 14 Two intake valves 28 and exhaust valves 29. Therefore, the camshaft 41 is not disposed between the cylinder head 14 and the cylinder head cover 15, the degree of freedom of arrangement of the injector housing 114 can be increased, and the distance between the fuel supply passage 119 and the passage 129 directly provided in the cylinder head cover 15 can be increased. Configurable degrees of freedom.

The second injection valve 108 of the injector 25 is supported on the cylinder head cover 15, and a part of the compressed air supply passage 126 that supplies compressed air to the second injection valve 108, that is, the channel 129 is directly provided on the cylinder head cover 15. The surroundings of the cylinder head cover 15 are not provided with components for introducing the compressed air into the injectors 25, so that the enlargement of the engine and the complication of the structure around the engine can be avoided.

The two ends of the cylindrical positioning pin 130 straddling the joint surface of the cylinder head 14 and the cylinder head cover 15 are inserted into the cylinder head 14 and the cylinder head cover 15 to form a part of the compressed air passage 126 between the cylinder head 14 and the cylinder head cover 15 respectively. The channels 128 and 129 where the head cover 15 is directly installed are connected through the aforementioned positioning pin 130, so that the relative positions of the cylinder head 14 and the cylinder head cover 15 are determined by the positioning pin 130, even if the injector 25 is placed between the cylinder head cover 15 and the cylinder head 14 The upper cooperative action is supported, and excessive stress is not generated on the injector 25. Applying the positioning pin 130 as a connection member between the passage 128 of the cylinder head 14 and the passage 129 of the cylinder head cover 15 eliminates the need for a dedicated part for connecting the passages, and contributes to a reduction in the number of parts.

Since the metal hole 131 is formed in the positioning pin 130, the pressure of the compressed air supplied to the injector 25 can be adjusted, and when this pressure adjustment is performed, dedicated parts are not required, which contributes to a reduction in the number of parts.

The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and various design changes can be made without departing from the description of the scope of the invention.

According to the first aspect of the present invention, the intake air flowing into the combustion chamber from one of the plurality of intake ports, that is, from the intake port on one end side, is guided by the guide wall of the top wall of the combustion chamber to bypass the spark plug and flow through the combustion chamber, This makes it possible to achieve lean burn and reduce fuel costs.

According to the second aspect of the present invention, the injection valve and the spark plug are arranged in the center of the combustion chamber to realize the compactness of the cavity, improve the stratification of the mixed gas and the compression ratio, thereby improving the combustion efficiency and further reducing the fuel cost.

According to the third aspect of the present invention, it is possible to supply micronized fuel to the combustion chamber, and by spraying the mixed gas containing the micronized fuel into the cavity of the piston, the combustion efficiency can be further improved and the fuel cost can be reduced.

According to the fourth aspect of the present invention, the influence of the vortex in the combustion chamber can be suppressed, the agitation of the mixed gas due to imbalance can be prevented, a layered state with a richer mixing ratio can be formed at the bottom of the aforementioned cavity, and the ignition performance can be improved, thereby passing Greater lean burn for lower fuel costs.

Claims (1)

1. a kind of four-stroke engine, on the cylinder head (14) that is provided with a pair of air inlet (20,21) that opens in combustion chamber (19), installs the spark plug facing described combustion chamber (19) ( 26), characterized in that, In a pair of air inlets (20, 21) arranged in parallel, the air inlet (21) on one end side of the parallel direction deviates from the center of the combustion chamber (19) and is close to the center of the combustion chamber (19). , the spark plug (26) is mounted on the cylinder head (14), and is formed at a position close to the intake port (20) of the pair of intake ports (20, 21) which is different from the intake port (21) on the one end side Separate exhaust port (22); Around the opening end of the air inlet (21) on the one end side to the combustion chamber (19), a guide wall (142) is arranged on the top wall (19a) of the combustion chamber (19), and the guide wall (142) guiding the intake air flowing into the combustion chamber (19) from the intake port (21) on the one end side to bypass the spark plug (26); A cavity (143) is provided at the central part of the face of the piston (17) facing the combustion chamber (19), and the injection valve (108) that directly injects fuel into the combustion chamber (19), a pair of intake ports (20 , 21), and the spark plug (26) is arranged on the cylinder head (14), so that the pair of intake ports (20, 21), exhaust port (22) and spark plug (26) surround the injection valve (108); The injection valve (108), which injects fuel atomized by compressed air, is arranged on the cylinder head (14) so that the tip protrudes into the cavity (143) of the piston (17) at the top dead center. superior; A protrusion (144) protruding to the side of the piston (17) is protrudingly provided on the top wall (19a) of the combustion chamber (19), and the spark plug (26) is mounted on the cylinder head (14) so that its tip is disposed on the top wall (19a) of the combustion chamber (19). below the tip of the injection valve (108).

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