JPH0447402Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a four-stroke water-cooled diesel engine suitable for outboard motor engines and the like.

In conventional diesel engines, the cylinder block and cylinder head are made of cast iron, so there are problems in that the weight is large and the output per unit weight is small. In addition, in conventional products, the cylinder block and cylinder head are separate parts, and they are fastened together with bolts with a gasket in between, so there is a problem that the number of parts increases and there is a risk that the seal at the gasket part may be incomplete. There are other problems.

In order to solve the above-mentioned conventional problems, the present invention aims to provide a diesel engine in which the cylinder block and cylinder head are integrally molded from aluminum (including aluminum-based alloys). .

In FIG. 1, which is a vertical cross-sectional view, the center line CC of the crankshaft 1 is vertical, and the flywheel 2 is attached to the upper end of the crankshaft 1. The illustrated engine is for an outboard motor, and an involute spline 3 is provided on the inner periphery of the lower end of a crankshaft 1 to connect an output shaft (not shown). In the illustrated engine, two cylinders 5 are arranged vertically, and the center line OO of each cylinder extends horizontally in the longitudinal direction of the ship. 6 is a piston, and 7 is a connecting rod.

The cylinder block 10 and cylinder head 11 are integrally molded from a cast product whose main component is aluminum. A cooling water chamber 12 is provided inside the block 10 and head 11. Cooling water is supplied to the chamber 12 by a cooling water pump (not shown). An exhaust port 13 and an intake port 14 are provided within the head 11. The head 11 also has a cylindrical boss 20 that supports the stems 17 and 18 of the exhaust valve 15 and the intake valve 16, and a cylindrical boss 22 that forms a mounting hole for the fuel injection nozzle 21.
is provided. Also, exhaust manifold 28 (fifth
) is also provided integrally with the head 11. One exhaust valve 15 and one intake valve 16 are provided for each cylinder 5. A total of four valves 15 and 16 are arranged vertically in a horizontal position, and are driven by a common camshaft 23 via a valve arm 24 as will be described later. The case 26 of the valve arm chamber 25 in which the camshaft 23 and the valve arm 24 are housed is connected to the cylinder head 11.
A belt is fastened to the end face 47 of.

The crankcase 27 is the part 2 on the block 10 side.
9 and a portion 30 on the opposite side. Portion 29 is integrally molded with block 10, and portion 30 is connected to portion 29 by bolt 34.
Fixed. The mating surfaces of both portions 29 and 30 include the crankshaft centerline C--C and are perpendicular to the cylinder centerline O--O. Part 30 is also block 1
It is made of the same material as 0.

Next, the structure of each part will be explained in detail. In FIG. 2, which is an enlarged partial view of FIG. 1, a liner 31 forming the sliding surface of the piston 6 is made of cast iron and is incorporated into the block 10 by casting. An alloy layer is formed on the contact surface between the liner 31 and the block 10 during casting, and the liner 31 is fixed to the block 10 by the alloy layer. The tip 32 of the liner 31 projects a small distance ₁ toward the cylinder head 11 from the top ring 33 of the piston 6 at the top dead center position shown, and is located relatively far from the explosion surface 35 of the head 11.
That is, the distance from the explosion surface 35 to the liner tip 32 is set as large as possible within a range that does not hinder the sliding of the ring 33. 36 is the explosion surface 35
In other words, the corner part near the outer periphery of the combustion chamber 37
The block 10 and the head 11 are continuous in the vicinity of the block 10 and the head 11. The cross section of a corner surface 36' of this portion 36 facing the combustion chamber 37 is shaped like an arc with a radius R.

By employing the above structure, the strength of the corner portion 36 can be sufficiently increased against the explosive force within the combustion chamber 37. That is, stress caused by the above-mentioned explosive force tends to concentrate on the corner portion 36, but by rounding the corner surface 36', the stress on the portion 36 can be dispersed and cracks etc. can be prevented from occurring in the portion 36. Moreover, since the length of the portion 36 is set large, the radius R can be set large, and therefore the stress dispersion effect can be enhanced and sufficiently high strength can be obtained.

Tests have confirmed that the strength of the portion 36 can be sufficiently increased by setting the radius R to a value that is approximately 2% or more of the cylinder inner diameter and less than or equal to the distance to allow movement of the piston 6. That is, if the ratio of the radius R to the cylinder inner diameter is r%, then
As shown in FIG. 3, in a range where the ratio r is smaller than about 2%, the stress δ decreases more rapidly as the comparison r increases, but when the comparison r exceeds about 2%, the amount of change in the stress δ becomes small. Therefore, if the comparison r is about 2% or more, the strength of the portion 36 in FIG. 2 can be sufficiently increased.

In FIG. 2, there is a cylinder block portion 39 surrounding the tip end 38 of the liner 31 and the cylinder head 1.
1 bulges outward (in the direction of arrow S) from the cylinder block portion 40 closer to the crankcase.
When the portion 39 has a thick structure in this way, the portion 39 can be prevented from being significantly deformed outward S when subjected to explosive force, and a gap can be prevented from forming between the portion 39 and the liner 31. Therefore, the gas in the combustion chamber 37 will not escape from between the liner 31 and the block 10 to the crank chamber, and high engine performance can be maintained. Since not much explosive force is applied to the crankcase side portion 40 of the block 10, there is no strength problem even if the portion 40 is made thinner, and the weight can be reduced by making the portion 40 thinner. At the same time, if you add meat to part 39,
Since the cross-sectional area of the portion 39 becomes larger and the area of the portion 39 that receives the force in the cylinder direction applied to the explosion surface 35 becomes larger, the stress in the corner portion 36 can also be reduced.

In FIG. 4, which is an enlarged schematic diagram of FIG. 2,
The inner surface of the liner 31 is honed. The honing surface 41 is provided on the inner surface of the liner from a portion on the crank chamber side to a portion 42 near the tip. The portion 42 is located at a distance ₂ of about 1 to 4 mm from the top spring 33 at the top dead center position toward the explosion surface 35, and the top spring 33
always slides on the honing surface 41. The inner circumferential surface portion 43 from the portion 42 of the liner 31 to the tip 32 is relative to the honing surface 41.
It is deflected radially outward by a distance ₃ of about 0.1 to 0.2 mm to form a honing relief. This provides the following advantages: That is, the honing tool is inserted into the liner 31 from the crank chamber side, but since the cylinder head 11 gets in the way at that time, honing cannot be performed up to the liner tip 32. Therefore, if the liner 31 before honing has the same inner diameter up to the tip 32, a honing boundary (step) will occur near the tip after honing, and the inner peripheral surface of the tip will have a smaller diameter than the honed surface 41. As a result, the piston 6 gets caught in the small-diameter tip portion of the piston 6, but in the illustrated structure, the tip portion 43 has a clearance, so such a problem does not occur. Also, since the honing relief 43 is provided in the liner 31, the block 10 (aluminum) will not be honed and therefore the honing tool will not become clogged.

In FIG. 2, the ceiling 45 of the cylinder head 11 forming the explosion surface 35 has a wall surface 46 opposite to the explosion surface 35 facing the cooling water chamber 12. Cooling water chamber 1
2, the chamber 12a near the center of the cylinder is farther from the explosion surface 35 than the chamber 12b near the outer periphery, and the ceiling 4
The wall thickness (for example, h) of No. 5 is larger at the center portion than at the outer periphery portion. By changing the wall thickness of the ceiling 45 in this way, the explosion surface 3
The strength of the ceiling 45 can be sufficiently increased against the explosive force applied to the ceiling 45, and the average wall thickness of the ceiling 45 can be reduced to reduce the weight. In the illustrated embodiment, the wall thickness of the ceiling 45 changes in stages, but it is also possible to make the entire wall surface 46 generally tapered so that the wall thickness of the ceiling 45 increases smoothly toward the center. By doing so, the strength can be further increased.

As shown in Fig. 1, the cylinder head 11 has intake and exhaust valves 15, 16 and ports 13, 14 inside.
, the total height H from the explosion surface 35 to the end surface 47 is large. Further, inside the head 11, there are provided a large number of ribs 48 which constitute partition walls of the boss 20, ports 13, 14, and cooling water chamber 12. In this way, the total height H of the head 11 is large,
Moreover, since it is reinforced with a large number of bosses 20 and ribs 48, the strength of the head 11 is high.

In FIG. 5, which is a - sectional view of FIG. 1,
The boss 22 for the fuel injection nozzle 21 is also attached to the head 1.
The strength of 1 is increased. Since the boss 22 extends from near the center of the ceiling 45 roughly along the center of the cylinder, compared to the ribs 48 of the other bosses 22 (FIG. 1),
The reinforcing effect on the head 11 is great. . Further, the nozzle 21 is combined with the fuel injection pump 49 to constitute a unit injector 50, and the injector 50 is attached to the boss 22 as described below, thereby further increasing the strength of the head 11.

First, the general structure of the unit injector 50 will be explained. The injector 50 has the sleeve 98 of the nozzle 21 directly connected to the tip of the body 91 of the pump 49. By reciprocating the plunger 93 within the barrel 92 attached inside the body 91, the high pressure fuel oil passage 94 inside the body 91 is Fuel is supplied from the pump 49 to the nozzle 21 through the pump 49. The injector 50 has an annular step 95 near the tip of the body 91 and in the middle of the sleeve 98, and when the step 95 is pressed against the step on the inner circumference of the boss 22, the part of the body 91 protruding from the boss 22 is pressed. It is fastened to the head 11 with a metal fitting 96. Therefore, an initial compressive force is applied to the center of the ceiling 45 by the injector 50 to counteract the explosive force, and in this respect as well, the head 11
The strength of the ceiling 45 has been increased, and the amount of deformation of the ceiling 45 has been reduced.

In addition, the injector 50 has a large diameter portion that constitutes the pump 49, and the large diameter portion (large diameter portion of the body)
The boss 22 also fits into the boss 22. Therefore, the boss 22 becomes a large reinforcing portion with a large diameter, and the strength of the head 11 can be increased in this respect as well.

The nozzle 21 opens its injection port when high pressure is supplied from the pump 49. As described above, in the unit injector 50, the pump 49 and the nozzle 21 are connected only by the short oil passage 94 in the body 91, so that the fuel pressure in the pump 49 is accurately transmitted to the nozzle 21. Therefore, fuel can be injected from the nozzle 21 in a manner that accurately corresponds to the pressure within the pump 49 over the entire range of changes in the engine speed and the entire range of changes in the fuel injection amount, thereby making it possible to prevent secondary injection. Moreover, since the pressure loss within the oil passage 94 can be significantly reduced, the injection pressure of the nozzle 21 can be increased and the atomization of the spray can be promoted. Moreover, the injection operation of the nozzle 21 is not delayed with respect to the pressurizing operation of the pump 49. In this way, secondary injection and injection delay can be prevented, and the atomization of the spray can be promoted, so the best combustion state can be maintained and engine performance can be improved. Furthermore, since injection delays can be prevented, performance during high-speed operation can be improved. Furthermore, unlike conventional products, there is no need to provide a timer for adjusting the injection timing, and the structure can be simplified.

The tip of the nozzle 21 is exposed in the combustion chamber 37 at approximately the center of the explosion surface 35, and the head 11 is not provided with a swirl chamber (auxiliary combustion chamber). Since the engine is of the direct injection type, the unit injector 50 can be supported over the entire height H of the head 11. Therefore, injector 50
The mounting state of the injector 50 is stabilized, and the distance from the explosion surface 35 to the other end (protector 65) of the injector 50 is reduced, making it possible to downsize the entire engine. That is, the unit injector 50
Although the overall length is long, by using a direct injection type engine, it is possible to prevent the engine from becoming larger. Incidentally, if the vortex chamber is provided in the head 11, the injector 50 will be located away from the explosion surface 35 by the amount of the vortex chamber, so the head 11 and the case 26 will need to be made larger.

The following advantages can also be obtained by using a direct injection type. In other words, if a vortex chamber is provided,
When the flame jets out from the swirl chamber to the combustion chamber 37, a large thermal load is applied to the inner surface of the communication passage between the swirl chamber and the combustion chamber 37. On the other hand, in the direct injection type, no large local heat load is applied to the head 11 or block 10. Therefore, although aluminum has low heat resistance, the head 11 and block 10 will not be damaged by heat.

Also, aluminum has low heat resistance but high thermal conductivity, so it
The heat added to the chamber 12 is quickly discharged to the cooling water in the chamber 12. Therefore, the block 10 and the head 11 are not subjected to vortex heating, and damage due to heat can also be prevented in this respect.

The piston 6 has a recess that serves as the combustion chamber 37 at the center of the top, and the top of the piston, at top dead center, is close to the explosion surface 35 and the rounded corners around it with almost no gap. I'm starting to do that.

Although the illustrated explosion surface 35 is flat, the explosion surface 35
5 can also be formed into a tapered (conical) concave surface. In this way, in the cross section shown, an arch structure consisting of the block 10 and the head 11, that is, the blocks 10 on both sides of the piston 6 are formed.
Since the strength of the arch structure in which the legs are the legs and the head 11 is the ceiling is increased, the strength of the block 10 and the head 11 can be increased.

Next, valves 15 and 16 (valve 16 in FIG.
(only shown in the figure) and the drive mechanism of the pump 49 will be explained.
In addition to the camshaft 23 and the valve arm 24, a valve arm 51 for the pump 49 is also accommodated in the valve arm chamber 25.
Further, the stems 17 and 18 of the valves 15 and 16 and the pump 49 protrude from the head 11 and enter into the case 26. O ₁ -O ₁ is a vertical center plane including the center of the cylinder, and the stems 17 and 18 are adjacent to, for example, the left side of the center plane O ₁ -O ₁ when viewed in the direction of movement of the hull. The tips of the stems 17 and 18 are located relatively close to the head end surface 47. A protector 52 is attached to the tips of the stems 17 and 18, and an adjustment screw 5 is fixed to one end of the valve arm 24 with a lockite 53.
4 is in contact with the protector 52. The valve arm 24 is provided with a tappet 55 in the middle part.
5 is driven by a cam 56 on the camshaft 23. The other ends of the four valve arms 24 in total are supported by a common valve arm shaft 57. The valve arm shaft 57 is vertical and supported by the case 26. Further, the valve arm shaft 57 is located away from the center plane O ₁ -O ₁ to the left, and its outer circumferential surface is located at a position slightly away from the head end face 47, and its center 57' is located at a distance from the valve arm 15, 16 in the closed position. It is located closer to the end surface 47 by about 2 to 3 mm (about 1/3 of the valve lift) than the end surface of the protector 52 (the contact surface of the screw 54).

The camshaft 23 is located at the rear of the valve arm 24 (on the side opposite to the end surface 47) and to the left of the nut 53, and is supported by the valve arm chamber case 26. The shaft 59 of the valve arm 51 extends vertically at a position adjacent to the right side of the center plane O ₁ -O ₁ and is aligned to the right of the camshaft 23 . Axis 59 is also case 2
6 is supported. The two valve arms 51 (only one shown) are supported at their intermediate portions by a common support shaft 59, and a cam follower 60 provided at one end abuts a cam 61 on the camshaft 23 from behind. An adjusting screw 63 is fixed to the other end of the valve arm 51 by a lock nut 62. The tip of the screw 63 is in contact with the protector 65 at the tip of the plunger 93. The screw 63 is located relatively far to the right with respect to the center plane O ₁ −O ₁ , and therefore the injector 50
As the whole moves toward the nozzle 21 side, the center plane O ₁ −
It is slanted to approach O ₁ .

An opening 66 is provided on the rear surface of the case 26 from the right end to a portion slightly toward the left end. Case 2
6 has a lid 67 attached to the opening 66 with bolts 68. A lever-type decompression mechanism 70 is attached to the left side of the case 26. The decompression mechanism 70 is used to manually open the valve from the outside when starting the engine, and the valve arm 24 is provided with an arm 71 that is driven by the decompression mechanism 70.

According to the above structure, the rotation of the camshaft 23 causes the cam 56 to drive the valves 15 and 16 via the valve arm 24, and at the same time, the cam 61 drives the plunger 93 of the pump 49 via the arm 51. Valve 1
The drive timing of 5, 16 and pump 49 is determined by screw 5.
It can be adjusted by changing the positions of 4 and 63.

When performing this adjustment work, the camshaft 23 and the valve arm shafts 57 and 59 are supported by the valve arm chamber case 26, but since the case 26 has an opening 66,
Adjustment work can be performed by simply removing the lid 67 covering the opening 66 without removing the camshaft 23 or the valve arm shafts 57, 59. Also, since the screw 63 and lock nut 62 face the opening 66,
By removing the lid 67, the screw 63 can be removed from the opening 66.
The position can be easily adjusted. Also screw 5
4 and the lock nut 53, the shafts 23 and 59 are left and right apart, so there is a gap 72 between the shafts 23 and 59.
Adjustment of the screw 54 can be easily performed through the opening 66.

As shown in FIG. 1, the camshaft 23 is supported by a case 26 at both ends and a middle portion. In each cylinder 5, the valve drive cams 56, 56 are distributed above and below the pump drive cam 61. Further, the cam 61 is at the same height as the cylinder center line OO. camshaft 23
A pump shaft 74 of a lubricating oil pump 73 is connected to the lower end of the lubricating oil pump 73 . The pump 73 is bolted to the lower surface of the case 26. The inlet of the pump 73 is connected to an oil pan (not shown) through an oil passage 75 made of a drilled hole provided in the case 26, head 11, and block 10. Oil pan is crankshaft 1
It is formed by a case surrounding an output shaft (not shown) extending downward from the output shaft. The outlet of the pump 73 is connected to various parts of the engine through the case 26, the head 11, and a bore hole oil passage (not shown) in the block 10.

The upper end of the camshaft 23 protrudes from the case 26, and a pulley 76 fixed to the protruding upper end is connected to a pulley 77 fixed to the upper part of the crankshaft 1 via a timing belt 78. A power generating device 79 is attached to the flywheel 2 above the pulley 77 . A ring gear 80 is provided on the outer periphery of the flywheel 2, and a starter 81 for driving the gear 80 is attached to the crankcase portion 30. At the top of the bottom wall (front wall) of the case portion 30, there is a filler port 82 that projects obliquely upward.
is provided. A governor 83 is attached to the cylinder block 10, and a fuel injection amount increasing device 87 for starting is attached to the cylinder head 11. The governor 83 is driven by a timing belt 78. Governor 83 and increase device 8
7 is connected to a plunger 93 of the fuel injection pump 49 in FIG. 5 via a lever mechanism 86.

As shown in FIG. 5, at a position adjacent to the rear of the crankcase 27, a governor 83 is provided on the right side of the cylinder block 10, and a lubricating oil strainer 84 is provided on the left side of the block 10. Further, the fuel injection pump 49 is integrated into the head 11 together with the nozzle 21 as described above. In this way, in the illustrated engine, among the large equipment attached to the engine, the pump 49 is built into the head 11, and the governor 83 and lubricating oil strainer 84 are built into the block 1.
Since the engine is distributed to the left and right sides of 0, the entire engine becomes approximately egg-shaped when viewed from above as shown in FIG. 5, and has a shape suitable for an outboard motor engine. Note that the entire engine is covered with an outboard motor case (not shown).

Reference numeral 85 denotes an intake pipe, one end of which is connected to the intake port 14 on the right side of the head 11, and the other end opened near the bottom of the crankcase 27. Intake pipe 8
5 is a cylinder block 10 and a crankcase 2
7, and the inlet side part wraps around to the front of the crankcase 27 to form the center plane O ₁
It has reached the vicinity of −O ₁ . By employing such a long intake pipe 85, it is possible to enhance the intake inertia effect and improve engine performance.

As mentioned above, the intake pipe 85 wraps around from the right side of the crankcase 27 to the front, and the starter 81 protrudes from the crankcase 27 to the left front.
In this respect as well, the left-right balance of the entire engine can be maintained. Inside the valve arm case 26,
By protruding the injector 50 to the right, providing the valve arm 51 in the center, and providing the camshaft 23 and the valve arm 24 on the left side, the left-right balance of the case 26 can be maintained.

According to the structure explained above, the cylinder block 10 and cylinder head 11 of the diesel engine
Since the cylinder block and head are integrally molded from aluminum, the weight can be reduced compared to conventional cylinder blocks and heads made of cast iron. Furthermore, by reducing the weight, it is possible to achieve higher output compared to conventional products of the same weight. There is no need to connect block 10 and head 11 with head bolts,
Of course, since there is no need to arrange a gasket between the two parts 10 and 11, the number of parts can be reduced, the weight can be reduced, and the assembly work can be simplified. Furthermore, head 1
Since there is no gasket between block 1 and block 10 as a heat insulating material, the flow of heat between them is improved and the cooling effect is also increased. Since there is no need for tightening with head bolts, there is no risk of deformation of the liner 31. Diesel engines have high cylinder pressure, but
There is no risk of combustion gas, cooling water, or lubricating oil leaking between the head 11 and block 10. In other words,
It is possible to increase the cylinder pressure and achieve high output without considering gas leaks. In conventional products, it was necessary to increase the wall thickness of the mating surface between the cylinder block and cylinder head in order to support the gasket, but this invention eliminates such thick wall parts and reduces weight. can.

Furthermore, as described above, by making various improvements to each part, the strength of the cylinder block 10 and cylinder head 11 can be sufficiently increased. Therefore, in a diesel engine with high cylinder pressure, the block 10 and head 11 are made of integrally molded aluminum.
In addition, the cylinder pressure can be increased to the extent that the desired high output can be obtained. In particular, in the present invention, a unit injector 50 consisting of an assembly of a fuel injection pump 49 and a fuel injection nozzle 21 is provided in the cylinder head 11, and the unit injector 50 and intake and exhaust valves 15, 16 are connected to valve arms 51, 24, respectively. They are driven by a common camshaft 23 via a common camshaft 23. In this way, in the present invention, the camshaft 23 for the injector 50 and the camshaft 23 for the valves 15 and 16 are made common, so that the structure can be made more compact. Also, since the valves 15 and 16 and the injector 50 are all driven by the valve arms 24 and 51, the valve 1
5, 16 or one of the injectors 50 to the camshaft 2
Compared to the case where the valve 1 is directly driven by the cam above
5, 16 and the operation timing of the injector 50 can be easily adjusted. Furthermore, as shown in Figure 5, the center plane
By arranging the injector 50 on one side of O ₁ -O ₁ and arranging the camshaft 23 and valves 15 and 16 on the other side, the valve arm chamber case 26 can be made more compact. Moreover, valve 1
In the illustrated embodiment, a gap 72 is provided between the shafts 23 and 59 in order to operate the timing adjustment screws 54 and lock nuts 53 for the shafts 23 and 59. Therefore, as described above, each component is arranged compactly inside the case 26, and the screw 54 located deep inside the valve arm chamber 25 is arranged in a compact manner.
and the nut 53 can be easily adjusted.

When performing the above adjustment work, the valve arm chamber case 26
The camshaft 23 and valve arm shafts 57, 59 are supported, but since the case 26 has an opening 66, the opening 66 can be opened without removing the camshaft 23 and valve arm shafts 57, 59. Adjustment work can be performed by simply removing the covering lid 67.

Furthermore, in the present invention, the valve arm chamber case 26 is fixed to the end surface of the cylinder head 11 opposite to the combustion chamber 37, the camshaft 23 is positioned within the valve arm chamber case 26, and the camshaft 23 is fixed to the valve arm chamber case 26. It is supported by

If the camshaft 23 is supported not by the cylinder head but by the valve arm chamber case 26 in this way, the explosion surface 35
Due to the explosive force applied to the cylinder head 1,
Even if a slight deformation occurs in the camshaft 1, the influence of the deformation can be effectively prevented from reaching the bearing portion of the camshaft 23.

In addition, a valve arm shaft 57 that supports the valve arm 24 for driving the intake and exhaust valves and a valve arm shaft 59 that supports the valve arm 51 for driving the unit injector are attached to the valve arm chamber case 26.
It has a structure in which it is disposed inside the camshaft 23 and around the camshaft 23 and supported by the valve arm chamber case 26. More specifically, the valve arm shaft 57 that supports the valve arm 24 for driving the intake and exhaust valves is arranged on the cylinder side with respect to the camshaft 23, and supports the intermediate portion of the valve arm 51 for driving the unit injector. The valve arm shaft 59 is connected to the cam shaft 23
and the unit injector 50 and supported by the valve arm chamber case 26.

According to this structure, the two valve arm shafts 57, 59 and their bearings serve as strength members for preventing deformation of the camshaft bearings.

In this way, it is possible to effectively prevent the deformation of the cylinder head 11 from affecting the bearing portion of the camshaft 23, and to increase the strength of the bearing portion of the camshaft 23, so that the camshaft 23 can be moved smoothly at all times. Moreover, it is possible to rotate the engine accurately and maintain a predetermined engine performance.

In particular, in engines that employ a unit injector, a large reaction force corresponding to the large required operating force of the unit injector is applied to the bearings of the camshaft and valve arm shaft. In the structure, the bearings of the camshaft and valve arm shaft mutually act as reinforcing parts, effectively preventing deformation of each part and preventing deviations in the operating timing of the cam, intake and exhaust valves, and unit injector. Can be effectively prevented.

Moreover, according to the present invention, the part of the unit injector 50 inside the valve arm chamber is disposed at a position shifted in the cylinder radial direction with respect to the cylinder center line O-O, and the camshaft 23 is placed on both sides of the cylinder center line O-O. It is located on the opposite side to the unit injector 50, and has a structure in which both valve arm shafts 57, 59 are arranged inside the valve arm chamber case 26 and around the cam shaft 23.

According to this structure, the various devices 23, 50, 57, 59, etc. can be dispersed and arranged compactly within the valve arm chamber 25, and the entire engine can be downsized.

In particular, by arranging the valve arm shaft 57 on the cylinder side with respect to the camshaft 23 and arranging the valve arm shaft 59 between the camshaft 23 and the unit injector 50,
The space around the camshaft 50 can be effectively utilized to arrange the valve arm shafts 57, 59, and compactness can also be achieved in this respect.

In this way, the present invention has improved strength in various respects, and for this purpose it is possible to adopt an aluminum cylinder head, and as mentioned above, it has been made lighter and more compact in various respects. This makes it possible to effectively make the entire engine lighter and more compact.

Note that when embodying the present invention, the layout of each part of the engine can be reversed left and right. The crankcase part 29 can also be provided separately from the cylinder block 10. The present invention can also be applied to engines with a single cylinder or three or more cylinders. A swirl chamber can also be provided within the head 11. The engine of the present invention can also be used for applications other than outboard motors. The present invention can also be applied to an engine in which the cylinder centerline O-O is vertical.

[Brief explanation of the drawing]

Figure 1 is a vertical sectional view of the embodiment, Figure 2 is an enlarged partial view of Figure 1, Figure 3 is a graph showing the relationship between corner radius and stress, and Figure 4 is an enlarged portion of Figure 2. 5 is a cross-sectional view of FIG. 1. 10... Cylinder block, 11... Cylinder head, 15... Exhaust valve, 16... Intake valve, 21... Fuel injection nozzle, 23... Camshaft,
24... Valve arm, 26... Valve arm chamber case, 49...
Fuel injection pump, 50...unit injector, 51...valve arm.

Claims (1)

[Scope of utility model registration request] The cylinder block and cylinder head of a diesel engine are integrally molded from aluminum.
A unit injector consisting of a fuel injection pump and a fuel injection nozzle is installed in the cylinder head, and the intake and exhaust valves of the unit injector are driven by a common camshaft via valve arms. A valve arm chamber case having an opening is fixed to the end face, the opening of the valve arm chamber case is closed with a lid, the camshaft is positioned within the valve arm chamber case, and the camshaft is supported by the valve arm chamber case. , the part of the unit injector inside the valve arm chamber is located at a position offset from the cylinder centerline in the cylinder radial direction, the camshaft is located on the opposite side of the unit injector across the cylinder centerline, and the intake and exhaust valves are The valve arm shaft that supports the valve arm for driving is placed inside the valve arm chamber case and on the cylinder side with respect to the camshaft, and is supported by the valve arm chamber case, and the middle part of the valve arm for driving the unit injector is supported by the valve arm chamber case. A four-cycle water-cooled diesel engine characterized in that a supported valve arm shaft is disposed inside a valve arm chamber case and between a camshaft and a unit injector and supported by the valve arm chamber case.