JP3589328B2 - Assembly structure of internal combustion engine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an assembly structure of a crankcase, a cylinder, a cylinder head, and the like of an internal combustion engine.
[0002]
[Prior art]
The crankcase of the internal combustion engine is usually a casting made of aluminum or an aluminum alloy for weight reduction, and long studs for penetrating the cylinder and the cylinder head and the like at the four outer peripheral portions of the cylinder hole with respect to the crankcase. A structure (for example, Japanese Utility Model Publication No. 57-45387) integrally fastened by bolts has been adopted as a general assembly structure of an internal combustion engine.
[0003]
At this time, a screw hole is formed directly on the mating surface of the crankcase with the cylinder, so that a stud-side end of a stud bolt penetrating the cylinder head and the cylinder is screwed.
[0004]
[Problems to be solved by the invention]
The four stud bolts penetrating the outer periphery of the cylinder hole can reduce the size of the entire internal combustion engine by reducing the distance between them, but when the distance is reduced, the stud bolt naturally approaches the cylinder hole. As a result, a stud bolt screw hole is formed close to the cylinder hole of the crankcase.
[0005]
However, when a screw hole is formed near a cylinder hole in a crankcase made of aluminum or an aluminum alloy, it is difficult to sufficiently secure the screw hole strength from the strength of the aluminum or aluminum alloy.
Therefore, in a crankcase made of aluminum or an aluminum alloy, a screw hole has to be formed at a certain distance from the cylinder hole, so that the interval between the stud bolts is widened and it is difficult to reduce the size of the entire internal combustion engine.
[0006]
In the same type of internal combustion engine series, when attempting to increase the displacement based on the existing internal combustion engine, it is intended to increase the diameter of the cylinder hole. As it approaches the screw hole, it is difficult to secure enough screw hole strength with the aluminum or aluminum alloy cylinder head as described above, so it is necessary to widen the stud bolt interval, so change the processing equipment As a result, it was not possible to easily increase the displacement.
[0007]
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to reduce the interval between bolts to reduce the size of an internal combustion engine, and to easily increase the displacement without changing processing equipment. The present invention provides an assembly structure of an internal combustion engine that can perform the above-described operations.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an internal combustion engine having a structure in which a cylinder and a cylinder head are integrally fastened to a crankcase by a long bolt penetrating an outer peripheral portion of a cylinder hole. After passing through a loose fitting hole formed on the mating surface of the crankcase with the cylinder, a nut member made of a flat high-strength material connecting between a plurality of screw holes fitted into the side wall of the crankcase is formed. The internal combustion engine was screwed on.
[0009]
A plate-shaped nut member connecting the multiple screw holes is fitted into the side wall of the crankcase, and a bolt is screwed into each of the multiple screw holes of the nut member. It can be simplified.
A screw hole for bolts is formed in a nut member made of a high-strength material that is separate from the members that make up the crankcase. Therefore, the distance between the bolts can be reduced, and the size of the entire internal combustion engine can be reduced.
[0010]
In addition, the diameter of the cylinder hole can be increased based on the existing internal combustion engine without changing the processing equipment, so that the displacement can be easily increased and the cost can be reduced.
[0011]
The nut member has an arc surface having substantially the same curvature as the inner peripheral surface of the cylinder hole of the crankcase, and the arc surface is formed on the inner peripheral surface of the cylinder hole by aligning the arc surface with the cylinder hole of the crankcase . The mounting structure of the internal combustion engine according to claim 1, which is fitted into the groove while being prevented from rotating, facilitates the assembling work and enlarges the diameter of the cylinder hole without changing the processing equipment. Can be done.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment according to the present invention will be described below with reference to FIGS.
The four-cycle internal combustion engine 1 according to the present embodiment is an OHC valve-type single-cylinder air-cooled internal combustion engine, and is mounted on a motorcycle (not shown) so that the crankshaft 7 is directed in the vehicle width direction.
[0014]
A cylinder block 3, a cylinder head 4, and a cylinder head cover 5 made of the same material are successively stacked on a crankcase 2 made of aluminum or an aluminum alloy in such a manner that the cylinder head 3 and the cylinder head cover 5 are largely inclined forward, and stud bolts 6 penetrating therethrough are used. 2, the cylinder block 3, the cylinder head 4 and the cylinder head cover 5 are integrally connected to each other (note that, in FIG. 1, the stud bolt 6 adjacent to the cylinder head cover 5 is on an extension of the stud bolt 6 penetrating the cylinder block 3). The reason why they are not located is that the right cross section of the cylinder block 3 is cut at a place different from the cross section passing through the crankshaft 7 and the camshaft 22).
[0015]
The crankshaft 7 is rotatably supported by the crankcase 2, and a cylinder sleeve 8 made of cast iron is integrally cast into the cylinder block 3, and the cylinder hole 9 of the cylinder sleeve 8 is slidable up and down. A piston 11 is fitted, and both ends of a connecting rod 14 are rotatably connected to a piston pin 12 of the piston 11 and a crank pin 13 of the crankshaft 7.
[0016]
The combustion chamber 16 defined by the substantially hemispherical concave surface 15 at the center of the lower surface of the cylinder head 4, the cylinder hole 9 of the cylinder block 3, and the top surface of the piston 11 intermittently fires near the top dead center of the piston 11. The piston 11 is pressed downward by the combustion gas generated by the ignition of the plug 17, and the crankshaft 7 is driven to rotate by the pressing force.
[0017]
An intake port 18 and an exhaust port 19 having a smaller diameter than the intake port 18 are formed on the upper and lower sides (left and right sides in FIG. 2) of the cylinder head 4, and an intake valve 20 and an exhaust gas are provided at openings of the intake port 18 and the exhaust port 19 on the combustion chamber 16 side. A valve 21 is provided so as to be openable and closable.
As shown in FIG. 2, the camshaft 22 is rotatably pivotally mounted on the cylinder head 4 via bearings 23 and 24, and the rocker arm shafts 25 and 26 penetrate the cylinder head 4 in the vehicle width direction. The rocker arms 27 and 28 are pivotally supported pivotally.
[0018]
As shown in FIG. 1, a drive sprocket 29 is integrally fitted to the crankshaft 7, a driven sprocket 30 having twice the number of teeth of the drive sprocket 29 is fitted to the camshaft 22, and the drive sprocket 29 and A cam chain 31 is bridged over the driven sprocket 30, and the intake valve 20 and the exhaust valve 21 are opened and closed once at a required timing every time the crankshaft 7 rotates twice.
[0019]
1, a generator 32 and a clutch 33 are disposed on the left and right sides of the crankshaft 7, respectively. The clutch 33 is connected to the rear wheels via a clutch and a transmission (not shown). Have been.
[0020]
The crankcase 2 is formed by combining a left crankcase 2L and a right crankcase 2R, which are divided into right and left by split surfaces 41L and 41R passing through the center axis of the cylinder hole 9, and a cylinder block of the crankcase 2. FIG. 3 shows a view in which the mating surface 42 with No. 3 is viewed from the front.
[0021]
A cylinder hole 43 is formed in the split surfaces 41L and 41R of the crankcase 2 composed of the left crankcase 2L and the right crankcase 2R so as to penetrate the mating surface 42 with the cylinder block 3. On the left side of the cylinder hole 43, a cam chain chamber 44 through which the long rectangular cam chain 31 passes is formed.
[0022]
On the outer periphery of the cylinder hole 43, loose fitting holes 45L and 45R are formed on the upper and left sides, respectively, near the cylinder hole 43, and screw holes 46L and 46R are formed on the lower left and right sides.
The loose fitting holes 45L and 45R are holes having a diameter larger than that of the stud bolt 6, the stud bolt 6 penetrates, and the stud side ends of the stud bolts 6 are screwed into the screw holes 46L and 46R.
[0023]
Long grooves 47L, 47R are formed in a substantially rectangular shape from the position where the loose fitting holes 45L, 45R of the inner peripheral surface 43a of the cylinder hole 43 penetrate to the upper divided surfaces 41L, 41R along the inner peripheral surface 43a. The two long grooves 47L, 47R communicate with each other at the split surfaces 41L, 41R to form one long groove.
[0024]
A nut member 50 as shown in FIGS. 6 and 7 is fitted into the long grooves 47L and 47R.
The nut member 50 is a high-strength material obtained by processing a steel plate, and has a bridge shape in which a long side of a long rectangular plate is cut off in a large arc shape on the left and right, and the arc surface 50a is a crankcase. It has the same curvature as the inner peripheral surface 43a of the second cylinder hole 43.
[0025]
The long grooves 47L and 47R formed in the crankcase 2 have grooves formed in a shape in which the nut member 50 is fitted, and the left half of the nut member 50 has a long groove as shown by a broken line in FIG. The right half of 47L fits into the long groove 47R, and the arc surface 50a matches the inner peripheral surface 43a of the cylinder hole 43.
[0026]
At both ends of the nut member 50, screw holes 51L and 51R are formed corresponding to the loose fitting holes 45L and 45R.
The screw holes 51L, 51R are formed at positions very close to the arc surface 50a, and the thickness between the screw holes 51L, 51R and the arc surface 50a is thin, but the screw holes 51L, 51R on the opposite side are formed. The thickness between the other side is large.
[0027]
The stud bolt 6 is a long bolt as shown in FIG. 8, and has screws 6a and 6b formed at both ends. The nut member 50 is fitted into the long grooves 47L and 47R of the crankcase 2 as described above. Then, two stud bolts 6, 6 are inserted into the loose fitting holes 45L, 45R from the mating surface 42 side of the crankcase 2, respectively, and the stud screws 6b, 6b are screwed into the screw holes 51L, 51R of the nut member 50. And erect it.
[0028]
The other two stud bolts 6, 6 are erected by screwing the stud-side screws 6b, 6b into the screw holes 46L, 46R of the crankcase 2 itself.
In this manner, in a state where four stud bolts 6 are erected on the mating surface 42 of the crankcase 2 around the cylinder hole 43, the cylinder blocks 3, the cylinder head 4 and the cylinder The head covers 5 are sequentially stacked.
[0029]
When assembling the cylinder block 3 to the crankcase 2, bolt holes 8 b respectively formed in four ridges 8 a bulging out on the outer periphery of the cylinder sleeve 8 at the outer periphery of the cylinder hole 9 of the cylinder block 3 are provided. The four stud bolts 6 erected as described above are passed through, and the mating surface of the cylinder block 3 is applied to the mating surface 42 of the crankcase 2 via the gasket 55.
At that time, the cylinder sleeve 8 integrally cast into the cylinder block 3 is fitted into a cylinder hole 43 formed in the crankcase 2 and a lower part thereof is inserted into the crankcase 2 to some extent.
[0030]
Therefore, the arc surface 50a of the nut member 50 is opposed to the outer peripheral surface of the lower part of the inserted cylinder sleeve 8.
Then, a cylinder head 4 and a cylinder head cover 5 are further superimposed on the cylinder block 3 sequentially, and a stud bolt 6 penetrates the cylinder head 4 and the cylinder head cover 5. A nut 52 is screwed into a nut-side screw 6 a of the stud bolt 6 exposed from the cylinder head cover 5. The cylinder block 3, the cylinder head 4, and the cylinder head cover 5 are integrally joined to the crankcase 2 by being tightened.
[0031]
Since the nut member 50 has the shape described above and is fitted into the long grooves 47L and 47R, the nut member 50 rotates together with the nut 52 via the stud bolt 6 when the nut 52 is tightened. There is no such thing.
FIG. 1 is a cross-sectional view showing the connected state. As described above, a portion through which the stud bolt 6 of the cylinder block 3 and the crankcase 2 penetrates is a cross section different from other portions.
[0032]
The internal combustion engine 1 has the above-described mounting structure, and the stud bolt 6 is screwed to a nut member 50 which is a steel plate fitted into the crankcase 2 separate from the crankcase 2 made of aluminum or an aluminum alloy. Therefore, the strength of the screw holes 51L and 51R is sufficiently ensured even though the screw holes 51L and 51R are close to the cylinder hole 43.
[0033]
Therefore, the stud bolt 6 can be brought close to the cylinder hole 43 while maintaining the screw hole strength, and the distance between the stud bolts 6 is reduced, thereby realizing the miniaturization of the entire internal combustion engine 1.
[0034]
In order to increase the displacement based on the internal combustion engine 1, the diameter of the cylinder hole is made somewhat larger without changing the position of the stud bolt, that is, without changing the size of the entire internal combustion engine, and further increasing the stud bolt 6. , As long as the strength of the screw hole is maintained, and it is not necessary to change the processing equipment, and the displacement can be easily increased.
[0035]
Since the nut member 50 is structured to be fitted into the long grooves 47L, 47R of the crankcase 2, the assembling work is easy, and even when the diameter of the cylinder hole is enlarged, the nut member can easily cope with and the processing equipment is changed. No need.
[0036]
In the present embodiment, the nut member 50 has two screw holes 51L and 51R to reduce the number of components. However, two nut members having one screw hole may be prepared. In this case, it is necessary to form the nut member so that it does not rotate when the nut is finally tightened.
Further, it is possible to use a through bolt instead of the stud bolt 6.
[0037]
【The invention's effect】
According to the present invention, since a screw hole into which a bolt is screwed is formed in a nut member made of a high-strength material separate from a member constituting the crankcase, the screw hole can be brought close to the cylinder hole of the crankcase. The strength of the screw holes can be easily ensured, so that the distance between the bolts can be reduced, and the overall size of the internal combustion engine can be reduced.
[0038]
In addition, the diameter of the cylinder hole can be increased based on the existing internal combustion engine without changing the processing equipment, so that the displacement can be easily increased and the cost can be reduced.
[0039]
The nut member is fitted into the groove formed on the inner peripheral surface of the cylinder hole of the crankcase with its rotation prevented, making it easier to assemble and increasing the diameter of the cylinder hole. It can be easily performed without changing the equipment.
[0040]
By adopting a structure in which a plurality of screw holes are formed in the nut member, the number of parts can be reduced and the assembling operation can be simplified.
[Brief description of the drawings]
FIG. 1 is a sectional view of an internal combustion engine according to one embodiment of the present invention.
FIG. 2 is another sectional view of the internal combustion engine.
FIG. 3 is a front view of a mating surface of a crankcase with a cylinder block.
FIG. 4 is a sectional view taken along line IV-IV in FIG. 3;
FIG. 5 is a sectional view taken along line VV in FIG. 3;
FIG. 6 is a top view of the nut member.
FIG. 7 is a side view of the same.
FIG. 8 is a side view of a stud bolt.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Crank case, 3 ... Cylinder block, 4 ... Cylinder head, 5 ... Cylinder head cover, 6 ... Stud bolt, 7 ... Crank shaft, 8 ... Cylinder sleeve, 9 ... Cylinder hole, 11 ... Piston, 12 ... Piston pin, 13 ... Crank pin, 14 ... Connecting rod, 15 ... Substantially hemispherical concave surface, 16 ... Combustion chamber, 17 ... Spark plug, 18 ... Intake port, 19 ... Exhaust port, 20 ... Intake valve, 21 ... Exhaust valve , 22 ... camshaft, 23, 24 ... bearing, 25, 26 ... rocker arm shaft, 27, 28 ... rocker arm, 29 ... drive sprocket, 30 ... driven sprocket, 31 ... cam chain, 32 ... generator, 33 ... clutch,
41L, 41R: split surface, 42: mating surface, 43: cylinder hole, 44: cam chain chamber, 45L, 45R: loose fitting hole, 46L, 46R: screw hole, 47L, 47R: long groove,
50: nut member, 51L, 51R: screw hole, 52: nut, 55: gasket.

Claims (2)

An internal combustion engine having a structure in which a cylinder and a cylinder head are integrally fastened together by a long bolt that penetrates an outer peripheral portion of a cylinder hole with respect to a crankcase,
The bolt is formed of a high-strength plate-shaped nut that penetrates a loose fitting hole formed in a mating surface of the crankcase with the cylinder and then connects a plurality of screw holes fitted in a side wall of the crankcase. An assembly structure for an internal combustion engine, which is screwed to a member. The nut member has an arc surface having substantially the same curvature as the inner peripheral surface of the cylinder hole of the crankcase, and a groove formed on the inner peripheral surface of the cylinder hole by aligning the arc surface with the cylinder hole of the crankcase. 2. The assembly structure for an internal combustion engine according to claim 1, wherein the fitting is prevented from rotating.

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