JPH09195851A - Assembly structure of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the strength of a screw hole, to reduce the distance between bolts, and to realize the small size, by screwing a bolt to a nut member which consists of a high strength of material, and is fitted in the side wall of a crankcase, after penetrating it to a loose fitting hole formed at the matching face of the cylinder of the crank case. SOLUTION: To the divided surface of a crank case 2, a cylinder hole is formed by penetrating the matching face with a cylinder block 3, and a loose fitting hole 45 R is formed at the upper side of the outer periphery of the cylinder hole in the lateral direction, while a screw hole is formed at the lower side in the lateral direction. And a long groove 47R is formed from the position penetrating the loose fitting hole 45R to the divided surface along the upper side. A nut member 50 is fitted to the long groove 47R. As the nut member 50, a high strength material made by processing a steel plate is used. Consequently, since the screw hole 51R to screw the bolt is formed to the nut member 50, the strength of the screw hole 51R can be secured easily, even though it is approached to the cylinder hole 9 of the crank case 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assembly structure for a crankcase, a cylinder, a cylinder head, etc. of an internal combustion engine.

[0002]

2. Description of the Related Art A crankcase of an internal combustion engine is usually a cast product made of aluminum or aluminum alloy for weight reduction, and a cylinder, a cylinder head, etc. are penetrated through the crankcase at four outer peripheral portions of a cylinder hole. The structure in which they are integrally fastened together with a long stud bolt (Japanese Utility Model Publication No. 57-45387, etc.) is adopted as a general assembly structure for internal combustion engines.

At this time, a screw hole is directly formed in the crankcase on the mating surface with the cylinder, so that the cylinder head,
The stud side end of the stud bolt that penetrates the cylinder is screwed.

[0004]

The four stud bolts penetrating the outer peripheral portion of the cylinder hole can be reduced in size by reducing the distance between them, but if the distance is reduced, the size of the internal combustion engine can be reduced. The stud bolt naturally comes close to the cylinder hole, and the stud bolt screw hole is formed close to the cylinder hole of the crankcase.

However, in a crankcase made of aluminum or aluminum alloy, when a screw hole is formed close to the cylinder hole, it is difficult to sufficiently secure the screw hole strength from the strength of aluminum or aluminum alloy. Therefore, in the case of a crankcase made of aluminum or an aluminum alloy, the screw holes have to be formed apart from the cylinder holes to some extent, and thus the interval between the stud bolts becomes wide, which makes it difficult to downsize the entire internal combustion engine.

Further, in the same type of internal combustion engine series, when the displacement is to be increased based on the existing internal combustion engine, the diameter of the cylinder hole is intended to be enlarged. As it comes close to the screw holes for stud bolts, it becomes difficult to secure sufficient screw hole strength with the cylinder head made of aluminum or aluminum alloy as described above. It was not possible to easily increase the displacement by changing the equipment.

The present invention has been made in view of the above points, and an object of the present invention is to reduce the interval between bolts to reduce the size of an internal combustion engine and to easily reduce the displacement without changing the processing equipment. The point is to provide an assembly structure of an internal combustion engine that can be increased.

[0008]

In order to achieve the above object, the present invention is integrally fastened together with a crankcase by a long bolt that penetrates a cylinder, a cylinder head and the like at an outer peripheral portion of a cylinder hole. In the internal combustion engine having the structure described above, the bolt is screwed to a nut member made of a high-strength material that is fitted into the side wall of the crankcase after penetrating a loose fitting hole formed in a mating surface of the crankcase with the cylinder. The internal combustion engine has a built-in structure.

Since a screw hole into which a bolt is screwed is formed in a nut member made of a high-strength material, which is separate from the member constituting the crankcase, the screw hole is screwed even if it is brought close to the cylinder hole of the crankcase. The strength of the hole can be easily ensured, and therefore the distance between the bolts can be reduced to reduce the size of the internal combustion engine as a whole.

Further, the diameter of the cylinder hole can be expanded 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.

The assembling work of the internal combustion engine according to claim 1, wherein the nut member is fitted into a groove formed in the inner peripheral surface of the cylinder hole of the crankcase while being prevented from rotating. And the diameter of the cylinder hole can be enlarged easily without changing the processing equipment.

By using the assembly structure of the internal combustion engine according to claim 1 or 2, wherein the nut member is formed with a plurality of screw holes, the number of parts can be reduced and the assembly work can be simplified. .

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. The 4-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) such that the crankshaft 7 is oriented in the vehicle width direction.

A cylinder block 3, a cylinder head 4, and a cylinder head cover 5 made of the same material as the crankcase 2 made of aluminum or aluminum alloy are sequentially stacked with a large forward inclination, and a stud bolt 6 penetrating them is used. , The crankcase 2, the cylinder block 3, the cylinder head 4 and the cylinder head cover 5 are integrally connected to each other (in FIG. 1, the stud bolt 6 penetrating the cylinder block 3 is
The stud bolt 6 adjacent to the cylinder head cover 5 is not located on the extension line of the cylinder block 3
This is because the right cross section of is cut at a portion different from the cross section passing through the crankshaft 7 and the camshaft 22).

The crankshaft 7 is rotatably supported by the crankcase 2, a cast iron cylinder sleeve 8 is integrally cast in the cylinder block 3, and a cylinder hole 9 of the cylinder sleeve 8 is slid vertically. A piston 11 is movably fitted, and both ends of a connecting rod 14 are rotatably attached to a piston pin 12 of the piston 11 and a crank pin 13 of the crankshaft 7.

A 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 piston 11
In the combustion chamber 16 defined by the top surface of the piston 11 and the combustion gas generated intermittently by the ignition plug 17 in the vicinity of the top dead center of the piston 11, the piston 11 is pressed downward and its pressing force is increased. The crankshaft 7 is thereby driven to rotate.

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 the combustion chambers of the intake port 18 and the exhaust port 19 are formed.
An intake valve 20 and an exhaust valve 21 are openably and closably provided at the 16-side opening. As shown in FIG. 2, the camshaft
A rocker arm is rotatably mounted on the cylinder head 4 via bearings 23 and 24, and rocker arm shafts 25 and 26 extend through the cylinder head 4 in the vehicle width direction.
27 and 28 are swingably supported.

As shown in FIG. 1, a drive sprocket 29 is integrally fitted to the crankshaft 7, and a driven sprocket 30 having twice the number of teeth of the drive sprocket 29 is fitted to the camshaft 22 to drive the drive. Cam chain 31 on sprocket 29 and driven sprocket 30
The intake valve 20 and the exhaust valve 21 are opened and closed once at a required timing every time the crankshaft 7 makes two revolutions.

Further, as shown in FIG. 1, a generator 32 and a clutch 33 are arranged on the left side and the right side of the crankshaft 7, and the clutch 33 is a rear wheel via a clutch and a transmission (not shown). Is connected to.

The crankcase 2 is a combination of a left crankcase 2L and a right crankcase 2R which are halved left and right by split surfaces 41L and 41R passing through the center axis of the cylinder hole 9. A front view of the mating surface 42 with the cylinder block 3 is shown in FIG.

The split surface 41L of the crankcase 2 consisting of the left crankcase 2L and the right crankcase 2R,
A cylinder hole 43 is formed in 41R so as to penetrate the mating surface 42 with the cylinder block 3, and the left crankcase 2
On the left side of the cylinder hole 43 of the L, there is formed a cam chain chamber 44 through which the vertically long rectangular cam chain 31 passes.

Then, on the outer peripheral portion of the cylinder hole 43, close to the cylinder hole 43, the loose fitting holes 45L, 45R,
Screw holes 46L and 46R are formed on the left and right sides, respectively. The loose fitting holes 45L, 45R are holes having a diameter larger than that of the stud bolt 6, and the stud bolt 6 penetrates therethrough, and the screw hole 46
The end portions of the stud bolt 6 on the stud side are screwed to L and 46R.

The loose fitting hole 45 on the inner peripheral surface 43a of the cylinder hole 43.
A long groove 47L that is recessed in a substantially rectangular shape from the position where L, 45R penetrates to the split surface 41L, 41R on the upper side along the inner peripheral surface 43a,
47R is formed, and both long grooves 47L and 47R are divided surfaces 41
L and 41R communicate with each other to form one long groove.

The long grooves 47L and 47R are provided with the grooves shown in FIGS.
A nut member 50 as shown in FIG. 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 out in a large arc shape on the left and right sides. It has the same curvature as the inner peripheral surface 43a of the second cylinder hole 43.

The long groove 47 formed in the crankcase 2
L and 47R each have a groove formed in a shape into which the nut member 50 is fitted. As shown by a broken line in FIG.
The left half of 50 is fitted in the long groove 47L and the right half is fitted in the long groove 47R,
The arc surface 50a coincides with the inner peripheral surface 43a of the cylinder hole 43.

Threaded holes 51L, 51R are formed at both ends of the nut member 50 in correspondence with the loose fitting holes 45L, 45R. The screw holes 51L and 51R are formed at positions extremely close to the circular arc surface 50a.
Although the wall thickness between 50a and 50a is thin, screw holes 51L on the opposite side,
The thickness between 51R and the other side is large.

The stud bolt 6 is a long bolt as shown in FIG. 8, and has screws 6a and 6b formed at both ends thereof. As described above, the long grooves 47L and 47R of the crankcase 2 are formed.
The nut member 50 is fitted into the nut, and the two stud bolts 6 and 6 are inserted into the loose fitting holes 45L and 45R from the mating surface 42 side of the crankcase 2, and the stud side screws 6b and 6b are screwed into the nut member 50. The holes 51L and 51R are screwed and set upright.

The other two stud bolts 6 and 6 are
The stud side screws 6b, 6b are erected by screwing them into the screw holes 46L, 46R of the crankcase 2 itself. Thus, the mating surface 42 of the crankcase 2 has its cylinder hole
With the four stud bolts 6 standing upright around 43, the cylinder block 3, the cylinder head 4, and the cylinder head cover 5 are sequentially stacked by being penetrated by the stud bolts 6.

When the cylinder block 3 is assembled to the crankcase 2, bolt holes formed in the four ridges 8a bulged on the outer circumference of the cylinder sleeve 8 on the outer circumference of the cylinder hole 9 of the cylinder block 3 respectively. The four stud bolts 6 standing upright as described above are passed through 8b, 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 the cylinder hole 43 formed in the crankcase 2, and the lower part thereof is inserted into the crankcase 2 to some extent.

Therefore, the inserted cylinder sleeve 8
The circular arc surface 50a of the nut member 50 faces the lower outer peripheral surface of the. Then, the cylinder head 4 and the cylinder head cover 5 are successively stacked on the cylinder block 3, the stud bolt 6 penetrates them, and the nut 52 is screwed to the nut side screw 6a 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 coupled to the crankcase 2 by being tightened.

Since the nut member 50 has the above-described shape and is fitted into the long grooves 47L and 47R, when the nut 52 is tightened, the nut member 50 is rotated through the stud bolt 6 together with the rotation of the nut 52. It does not rotate. FIG.
FIG. 4 is a cross-sectional view showing the coupled state, but as described above, the portions of the cylinder block 3 and the crankcase 2 through which the stud bolt 6 penetrates show a cross-section different from other portions.

The internal combustion engine 1 has the above-described assembly structure, and the stud bolt 6 is a nut member 50 which is a steel plate fitted into the crankcase 2 which is separate from the crankcase 2 made of aluminum or aluminum alloy. Since the screw holes 51L and 51R are screwed to the
Although L and 51R are close to the cylinder hole 43, they are sufficiently secured.

Therefore, the stud bolt 6 can be brought close to the cylinder hole 43 while maintaining the strength of the screw hole, and the distance between the stud bolts 6 can be reduced to realize the miniaturization of the entire internal combustion engine 1.

When the displacement of the internal combustion engine 1 is to be increased, the diameter of the cylinder hole is increased to some extent without changing the position of the stud bolt, that is, without changing the overall size of the internal combustion engine. It is possible to approach the stud bolt 6 within a range in which the strength of the screw hole is maintained, it is not necessary to change the processing equipment, and the exhaust amount can be easily increased.

The nut member 50 is a long groove of the crankcase 2.
Since it is a structure to be fitted in 47L and 47R, the assembling work is easy, and even when the diameter of the cylinder hole is enlarged, the nut member can be easily dealt with and it is not necessary to change the processing equipment.

In the present embodiment, the nut member 50
Has two screw holes 51L and 51R to reduce the number of parts, but two nut members with one screw hole may be prepared. In that case, both nuts should be tightened at the final tightening. It is necessary to make the nut member non-rotatable. It is also possible to use a through bolt instead of the stud bolt 6.

[0037]

As described above, according to the present invention, the nut member made of a high-strength material, which is separate from the member constituting the crankcase, is formed with the screw hole into which the bolt is screwed, so that the screw hole is the cylinder hole of the crankcase. The strength of the screw hole can be easily ensured even when the bolts are close to each other, so that the distance between the bolts can be reduced and the overall size of the internal combustion engine can be reduced.

Further, the diameter of the cylinder hole can be enlarged without changing the processing equipment based on the existing internal combustion engine, so that the exhaust amount can be easily increased and the cost can be reduced.

The nut member has a structure in which the nut member is fitted into the groove formed on the inner peripheral surface of the cylinder hole of the crankcase while being prevented from rotating, thereby facilitating the assembling work and expanding the diameter of the cylinder hole. This can be easily done without changing the processing equipment.

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 work can be simplified.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an internal combustion engine according to an 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 a 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 ... Cam shaft, 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, 46
L, 46R ... screw hole, 47L, 47R ... long groove, 50 ... nut member, 51L, 51R ... screw hole, 52 ... nut, 55 ... gasket.

Claims (3)

[Claims] 1. An internal combustion engine having a structure in which a cylinder, a cylinder head and the like are integrally fastened together with a crankcase by a long bolt penetrating at an outer peripheral portion of a cylinder hole, wherein the bolt is the cylinder of the crankcase. And a nut member made of a high-strength material that is fitted into the side wall of the crankcase after being passed through a loose fitting hole formed in the mating surface of the internal combustion engine. 2. The assembly structure for an internal combustion engine according to claim 1, wherein the nut member is fitted into a groove formed in an inner peripheral surface of a cylinder hole of a crankcase while being prevented from rotating. 3. The assembly structure for an internal combustion engine according to claim 1, wherein the nut member is formed with a plurality of screw holes.