JPS63143367A - Crankcase of engine - Google Patents

Abstract

PURPOSE:To facilitate assembly and increase strength by forming the bearing half bodies integrally at the opening port part of the joint surface of a crankcase with a cylinder block and installing a bearing half body which forms a pair with the bearing half body by bolts. CONSTITUTION:An engine is constituted of a crankcase 12 in the integral structure, cylinder block 13 fixed onto the crankcase 12 by bolts, and a head cover 14. On the joint surface S of the crankcase 12 with the cylinder block 13 in the upper part, an opening 17 for connecting the internal space of the crankcase 12 to the internal space of the cylinder block 13 is formed, and the lower side bearing half bodies 22... for supporting the center part and the right and left side edges of a crankshaft 21 are formed integrally onto the crankcase 12 at the position a little under the opening 17. Further, the opposed joint surfaces of the upper side bearing half bodies 23 are butt-jointed onto the upper part of the bearing half bodies 22 by bolts, and the crankshaft 21 is bearing- supported.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an engine crankcase that can be manufactured at low cost and that can increase the support strength of the crankshaft.

"Prior Art" Conventionally known engine crankcases are generally split into upper and lower parts or
As described in Publication No. 5612, it is divided into left and right parts, etc.
It was a multi-divided structure.

For example, a crankcase of the type that is divided into upper and lower parts will be explained with reference to FIGS. An upper bearing half 3 is integrally formed in the upper case 2, and a lower bearing half 4, which pairs with the bearing half 3, is bolted to the lower side of the upper bearing half 3. The crankshaft 5 is rotatably supported between 3.4 and 3.4.

``Problems to be Solved by the Invention J'' By the way, since this type of conventional crankcase has a multi-segment structure, ■ multiple relatively large and expensive molds are required; Each constituent member l,
There have been problems in that the mating surfaces of the two must be finished with high precision, which requires cutting, and (2) the number of assembly steps increases, resulting in increased costs.

In addition, in a normal reciprocating engine, the pressure applied to the piston at the time of explosion is transmitted to the crankshaft 5 via the connecting rod 6.
However, in the type of crankcase that is divided into upper and lower parts as shown in Figs. 1 and 2, the downward pressure acting on the crankshaft 5 at the time of the explosion is The upper bearing half 5 and upper case 2 that support the side bearing half 4 and the lower bearing half 1 are received. Therefore, the lower bearing half 4.5 and the upper case 2 must have considerably high rigidity, and for this reason, these members 2.4.5 have thick walls and are provided with a large number of ribs. and
This has led to the problem of increased weight.

The present invention has been made in view of the above circumstances, and is capable of reducing costs by requiring only one relatively expensive mold and reducing assembly man-hours, as well as increasing the supporting strength of the crankshaft. The purpose is to provide crankcases.

[Means for solving the problem-1 The crankcase 12 according to the present invention is not multi-divided but has an integral structure as shown in FIG. A bearing half 22 is integrally formed, and a paired bearing half 23 is bolted to the upper side of the bearing half 22, and both bearing halves 22.2
3, the crankshaft 21 is rotatably supported between the two.

``Function'' According to the above-mentioned crankcase, since it is an integral structure rather than a multi-divided structure, only one mold is needed to make it, the number of assembly steps is reduced, and the crankcase 12 can be configured like a conventional crankcase. Since cutting of the mating surfaces of the sliding members is naturally eliminated, costs can be reduced.

In addition, since the crankcase 12 has a one-piece structure, its rigidity is increased, and the lower bearing half 22, which is integrally made with the highly rigid crankcase, also has increased strength. Although the load acting through the piston 15, connecting rod 90, and crankshaft 21 during an explosion moves to the lower bearing half 22, it has sufficient resistance against it, and as a result, it is sufficient for high-speed engines. In addition, if it is sufficient to maintain the same level of strength as before, the wall thickness of the bearing halves 22, 23 and crankcase I2 may be made thinner or the number of ribs may be reduced accordingly. It is possible to reduce the weight, thereby reducing the weight.

"Example" Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

1 to 6 show a two-cylinder, one-stroke engine equipped with a crankcase according to the present invention, FIG. 4 is a partially sectional side view, and FIG. FIG. 6 is a cross-sectional view taken along the line ■-■, and a perspective view of the crankcase.

The engine shown in these figures has a crankcase I2,
The basic structure consists of a cylinder block 13 bolted to the crankcase 12, and head covers 1, 1 that close the upper opening of the cylinder block I3. The above-mentioned cylinder block I3 has a structure in which a normal cylinder block and a nolinder head are integrated, and a piston 15 is slidably fitted inside the cylinder block I3. Prepare your valve system.

To explain the crankcase I2 in detail, the crankcase 12 is not multi-divided and has an integral structure, and the inner space of the crankcase I2 is connected to the cylinder block 13 on the mating surface with the cylinder block 13 of the two parts. An opening 17 is provided in the right side wall in FIG. 5 for connecting the transmission +8A and the operation system 18f3 of the transmission 18A. A on the left side wall,
An opening 20 is provided for attaching a plate 52.

The crankshaft 21 is located in the upper opening 17 of the crankcase 12.
A lower bearing half 22 for supporting substantially the center and both left and right ends of the opening 17 is provided at a location slightly lower than the opening 17. These lower bearing halves 22 are connected to the crankcase 1
2 is made integrally by casting, and its lower end reaches the bottom of the crankcase 12. An upper bearing half 23 is bolted to the upper part of the lower bearing half 22 with their opposing mating surfaces abutted against each other. The crankshaft 21 is rotatably supported between these two bearing halves 22, 23.

A bearing 24.25 is disposed on the opposite side wall facing the opening 19 of the crankcase 12, and one end of each of the main shaft 26 and the counter shaft 27 that constitute the transmission 18A is rotated by the bearing 24.25. freely supported. A plurality of pairs of gears are respectively incorporated in the main shaft 26 and the counter shaft 27, and when a change pedal (not shown) is operated, the operation system 18B consisting of a gear shift spindle 28, a lift drum 29, etc. is operated. By engaging arbitrary gears of the pair of gear sets, the rotation of the main shaft 26 can be transmitted to the counter shaft 27 with an appropriate reduction ratio. The rotation of the counter shaft 27 is transmitted to the rear wheel via a chain wound around a sprocket 30 attached to the left end in FIG.

On the other hand, the other ends of the main shaft 26 and the counter shaft 27 are rotatably supported via bearings 32 and 33 by a transmission boulder 31 bolted to the crankcase 12 so as to close the opening 19. Each component constituting the transmission 18A and the operating system 18B is assembled in advance to this transmission holder 31, and installed in the crankcase 12 all at once.

An oil pump 35 is integrated into the transmission holder 31. The oil pump 35 includes a pump body 36 that is integrally formed with the transmission holder, a drive rotor 37 that is bolted to the main shaft 26 and rotates integrally with the main shaft 26, and a space between the drive rotor 37 and the pump body 36. It consists of a driven rotor 38 provided in
This oil pump 35 is also connected to the transmission +8A and the operation system 1.
Like 8B, it is assembled to the child transmission holder 3I and installed inside the crankcase 12. This oil pump 35
When activated, the oil accumulated at the bottom of the crankcase 12 is sucked into the pump 35 through the oil passage 40 connected to the strainer 39, and the sucked oil is absorbed into the transmission holder 31, which is integrally formed with the transmission holder 31. It is discharged from the discharge port 41. The discharged oil is divided into two systems, one of which is guided into the hollow part 27a of the counter shaft 27 through an oil passage 42 provided integrally with the transmission holder 31, and from there to the outside in the radial direction. While lubricating the joint portion between the counter shaft 27 and the transmission gear meshing with the same shaft 27 through a plurality of oil passages extending to An oil passage 43 extending radially outward formed at the left end of the kerosene, and a crankcase 12 connected to this oil passage 43.
It is guided into the hollow part 26a of the main shaft 26 through an oil passage 44 formed integrally with the main shaft 26, extends radially outward from there, and meshes with the main shaft 26 and the coaxial shaft 27 through a plurality of oil passages. Lubricate the joints with each of the transmission gears.

The oil of other systems is provided through an oil passage 45 integrally provided in the transmission holder 31 and an oil passage 45 integrally provided in the crankcase I2, which is connected to the oil passage 45 through a mating surface between the transmission boulder 31 and the crankcase 12. is led to the joint between the bearing half 22, 23 and the crankshaft 21 through an oil passage 46 and an oil passage 47 rising upward from the oil passage 46,
A clutch 48 that is operated on and off by a clutch lever (not shown) is attached to a portion of the main shaft 26 that protrudes further outward from the transmission boulder 31 that lubricates this portion, and the clutch 48 is equipped with four buffer mechanisms. The connecting gear 49A of the buffer mechanism 49 is engaged with a gear 50 formed integrally with the crankshaft 21. In addition, 51 is crank case 1
This is a clutch cover that is bolted to 2.

In addition, the left end of the crankshaft 21 in FIG.
C. A generator 52 is provided.

The A, C, and generators 52 used here are different from known ones in that the outer rotor 53 is directly fixed to the end of the crankshaft 21 by bolts 54 without having a tapered boss portion.

Further, the covers 55 of the A, C, and generators 52 are integrated with a chain cover 56 for covering the chain wound between the counter shaft 27 and the rear wheel.

Inside the cylinder block 13 is the cylinder sleeve 16.
The lower end of the sleeve 16 is set at the same height as the lower end of the cylinder block I3. Further, the lower end of the cylinder block 13 is set to substantially coincide with the lower end of the skirt of the piston 15 located at the bottom dead center.

At approximately the center in the height direction of the cylinder block 13 and slightly below the intake boat 62 and the exhaust boat 63, an inlet cooling water passage 64 and an outlet cooling water passage 65 are provided between the intake and exhaust boats 62. 63 and the combustion chamber 66, extending parallel to each other on the outside thereof so as to sandwich the connecting portion between them. Both cooling water passages f34.65 are connected via a communication passage 67 provided at the middle upper part of the left and right cylinders and a communication passage 68 formed at the right end of the cylinder block 13 in FIG. Also, the portion sandwiched between the intake boat 62 and the exhaust boat 63 (this is the cooling water passage 69
are provided to extend parallel to the cooling water passages 64 and 65, and the cooling water passage 69 is connected to the outlet cooling water passage 65 via an inclined communication passage 70. Further, a cooling water jacket 71 formed at the left end of the cylinder block 13 in FIG. 5 is connected to the cooling water passage 64. Note that 72A and 72B each indicate a cap for connecting the pipes. The cooling water passages 64, 65, 69 are formed simultaneously with the cylinder block 13 by casting when the cylinder block 13 is formed by casting, and the communication passages 67, 68, 70 that communicate them are formed by the cylinder block 13. It is made by cutting after being made. Note that when these cooling water passages 67 to 70 are formed by casting or cutting, the outer opening 08 that is formed is liquid-tightly closed by a plug member 73.

Further, in the cylinder block 13, an intake valve 81 and an exhaust valve 82 are provided above the combustion chamber 66 so as to be slidable in the vertical direction so as to extend parallel to the cylinder axis. Although the two surfaces of the combustion chamber 66 are formed flat to match the lower surfaces of the valves 81 and 82 arranged parallel to the cylinder axis, a recess 83 is formed in the upper surface of the piston 15. Therefore, the combustion chamber 66 has a swollen shape in the center so as to obtain good combustion efficiency. Further, the guide 84 that slidably supports the valves 81, 82 is formed integrally with the cylinder block 13, so that the valves 81, 82 can be effectively removed from heat. Further, the valve sort 85, which the valves 81 and 82 come into contact with when closing, is cast at the same time as the cylinder sleeve I6 when the cylinder block 13 is made.

Valve 8! , 82 are provided with cam shafts 86, 86. A sprocket 87 is attached to the right end of the camshaft 86 in FIG.
A cam chain 89 is wound between the sprocket 88 and the sprocket 88 integrally provided on the crankshaft. camshaft 86
The left end of the camshaft 86 in FIG. Support in the thrust direction is provided by a ring-shaped protrusion 86a provided at the center of the camshaft 86, which is formed in the cylinder block 13 and supported by a bearing. The arcuate groove portion 13a of the bearing formed therein,
14a. The reason why only the lower portion of the right end portion of the camshaft 86 is supported is because the direction of the shear force acting on the right end portion of the camshaft 86 from the cam chain 89 is only downward.

According to the engine with the above configuration, since the crankcase 12 is not a multi-segmented structure but an integral structure, the mold can be made by using Guicasting, and the conventional multi-segmented crank In addition to reducing assembly man-hours compared to the case, it also eliminates the need for machining the mating surfaces of the crankcase components, resulting in a significant cost reduction.

In addition, there is no need for bolts, packing materials, etc. used on land to connect the crankcase components, which also helps reduce costs.

Furthermore, the explosion load when the air-fuel mixture is combusted in the cylinder is applied to the piston 15, connecting rod 90, and crankshaft 21.
The lower side of the crankshaft 21 is supported through the roller bearing half 22
This is because the crankcase I2 has a one-piece structure that ensures high rigidity, and the lower bearing half 22 is integrally formed with this highly rigid crankcase 12. Therefore, the crankshaft support by the lower bearing half 22 can sufficiently withstand the high load at the time of an explosion, and can provide high-precision support. It is also fully compatible with rotary engines. On the other hand, if the same crankshaft support strength as the conventional one is sufficient, the crankcase I2 and the bearing halves 22 and 23 can be made thinner, or the number of ribs formed on the crankcase I2 can be reduced. In particular, the weight reduction required for motorcycles can be achieved.

Further, when assembling the transmission 18A', the transmission operation system 18B, and the oil pump 35 to the crankcase I2, they can be assembled in advance to the transmission holder 31, and the boulder 31 can be assembled all at once. Assembling work can be simplified, and maintenance work can also be performed without removing the cylinder block 13 from the crankcase 12 as in the conventional case.

Furthermore, since the drive rotor 37 of the oil pump 35 is directly attached to the main shaft 26, it is not necessary to separately provide a power transmission system that connects the moving parts of the engine and the pump 35 in order to drive the oil pump 35, as in the past. This reduces the number of parts and makes the engine more compact.

Furthermore, the oil path flowing from the pump 35 to the bearing side of the crankshaft 21 can be connected to the transmission holder 31 and the crankcase without using special members such as pipe materials. The oil passages 45, 46, 47 consisting of communication holes integrally provided in the transmission holder 31 and the crankcase 12 are connected to each other by butting the openings together using the mating surfaces of the transmission holder 31 and the crankcase 12. Since it is formed by the above structure, the number of parts can be reduced, and the number of connections at the end of the pipe material, where oil leakage is likely to occur, can be reduced as much as possible.

In addition, although the above embodiment describes an example in which the present invention is applied to a two-cylinder four-stroke engine, the present invention is also applicable to a four-stroke engine or a two-stroke engine having a single cylinder or a plurality of cylinders other than two. Of course, it can also be applied.

"Effects of the Invention" As explained above, according to the present invention, there is an engine crankcase that is made integrally without being divided into multiple parts, and the bearing half is integrally formed in the opening part of the mating surface with the cylinder block. A pair of bearing halves are bolted to the bearing halves, and the crankshaft is rotatably supported between these two bearing halves, so the crankcase can be easily rotated. Casting requires only one mold, and compared to conventional multi-segmented crankcases, the number of assembly steps is reduced, and the need for machining the mating surfaces of the crankcase components is eliminated, resulting in a significant cost reduction. In addition, there is no need for bolts, packing materials, etc. that were conventionally used to connect the crankcase components, which also helps reduce costs. Further, there is no problem of oil leakage from the connecting surfaces of the crankcase constituent members.

Furthermore, when the air-fuel mixture is combusted in the cylinder, the explosion load acts on the bearing half that supports the lower side of the crankshaft via the piston, connecting rod, and crankshaft, but the crankcase is integrally The structure ensures high rigidity, and since the lower bearing half is integrally formed with this highly rigid crankcase, the strength of the lower bearing half is also ensured sufficiently. ,therefore,
The crankshaft supported by the lower bearing half can sufficiently withstand the high load at the time of an explosion, provides highly accurate support, and is fully compatible with high-speed engines. On the other hand, if the same level of crankshaft support strength as before is sufficient, the crankcase and bearing halves can be made thinner, and the number of ribs formed on the crankcase can be reduced, especially for motorcycles. The required weight reduction can be achieved.

[Brief explanation of the drawing]

1 and 2 show a conventional example of a crankcase, FIG. 1 is an exploded perspective view of the crankcase, FIG. 2 is a conceptual diagram showing the crankshaft support structure of an engine equipped with the same crankcase, and FIG. The figure is a conceptual diagram of the crankcase of the present invention, Figures 4 to 6 show an embodiment of the present invention, Figure 4 is a partially sectional side view of the engine, and Figure 5 is the v of Figure 4. A sectional view taken along the line -■, and FIG. 6 is a perspective view of the crankcase. tt...Engine, 12...Crankcase, 13...Cylinder block, 14...
...Head cover, 21...Crankshaft,
22.23...Bearing half, 26...Main shaft, 27...Counter shaft, 31...
Transmission holder, 35 oil pump.

Claims (1)

[Claims] The engine crankcase (12) is integrally made without being divided into multiple parts, and the cylinder block (13) is fixed to the upper part of the crankcase. piston (15
), wherein a bearing half (22) is integrally formed in the opening part of the mating surface of the crankcase with the cylinder block (13), and the bearing half has a mating bearing. A crankcase for an engine, characterized in that a half body (23) is bolted together, and a crankshaft (21) is rotatably supported between these two bearing halves.