JPH03182671A - Cylinder body coupling structure for water-cooled engine - Google Patents

Abstract

PURPOSE:To make improvement of coupling rigidity to be compatible with reduction of size by forming a bolt head part containing recessed part in a cylinder body or a cylinder head and overlapping a part of the containing recessed part with a water-cooled jacket as seen from the axial direction of a cylinder. CONSTITUTION:Cylinder bolt holes 12c are formed adjacently to respective screw holes 12d for head on both sides. Arrangement is made such that the upper part of the cylinder hole 12c is overlapped with a screw hole 12d part as seen from a direction ex. tending at right angles with the axis of a cylinder. A head part 62a of a fixing bolt 62 is arranged in a bolt head containing recessed part 12b formed in the upper end part of the cylinder bolt hole 12c is arranged in a position where a part of the head containing recessed part 12b is overlapped with a part 60b of a water-cooled jacket 60, and the cylinder bolt hole 12c is arranged on the inner periphery side of a cylinder body 12 as much as possible. This constitution suppresses an external expansion amount of a boss part for a bolt hole, and prevents the increase of the size of the cylinder body.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cylinder body connection structure for a water-cooled engine in which a cylinder body is bolted and fixed to a crankcase, and in particular, the present invention relates to a cylinder body connection structure for a water-cooled engine in which a cylinder body is fixed to a crankcase with bolts. The present invention relates to a structure that can be miniaturized while improving performance.

[Conventional technology]

For example, in an engine used in a motorcycle, a cylinder body is mounted on the crankcase and connected with a fixing bolt, and a cylinder head is mounted on the cylinder body and connected with another fixing bolt. Common. To connect the above-mentioned crankcase and cylinder body, a connecting flange is extended outwardly at the signal part of the cylinder body to the crankcase side, and the flange and the connecting part of the crankcase are tightened with fixing bolts. The structure is common (for example, Utility Model Application Publication No. 48-10370
(See Publication No. 4).

[Problems to be solved by invention]

However, in the conventional structure in which the flange formed on the cylinder body is connected to the crankcase, there is a problem in that the cylinder body becomes larger as the flange extends outward in the diametrical direction of the cylinder, and the rigidity of the connection between the two increases. In order to increase the height, it is necessary to make the flange part considerably thick.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a cylinder body connection structure for a water-cooled engine that can be downsized while improving the rigidity of the connection between the cylinder body and the crankcase. There is.

[Means for solving problems]

The present invention provides a cylinder body coupling structure for a water-cooled engine, in which fixing bolts are disposed outside a water-cooled jacket formed around the cylinder, and the cylinder body is tightened and fixed to the crankcase by the fixing bolts. A bolt head accommodating recess in which the head of the fixing bolt is located is opened in the cylinder body or cylinder head on the mating surface thereof, and a part of the accommodating recess is formed so as to overlap with the water cooling jacket when viewed in the cylinder axis direction. It is characterized by

[Function] According to the cylinder body coupling structure for a water-cooled engine according to the present invention, the head of the fixing bolt is located at the mating surface of the cylinder body or the cylinder head. Since it is tightened, the joint rigidity is greatly improved compared to, for example, the case where the flange of the cylinder body is tightened.

In addition, since the flange is not extended outward as in the conventional example, the cylinder body does not become large. Since the fixing bolt insertion boss portions are formed close to each other so as to overlap with the water cooling jacket, it is possible to suppress the outward protrusion of the fixing bolt insertion boss portions, and from this point of view as well, it is possible to prevent the cylinder body from increasing in size.

Furthermore, the bolt head accommodating recess is the cylinder body,
Since the opening is on the mating surface of the cylinder head, when the cylinder head is removed, the head of the fixing bolt will be exposed to the outside, making it easy to assemble the cylinder body, and also making it easy to install and remove the cylinder head while mounted on the vehicle. It is possible.

(Example〕 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 to 8 are diagrams for explaining a cylinder body coupling structure of a four-stroke engine according to an embodiment of the present invention, in which FIG. 1 is a cross-sectional side view thereof, and FIG. 2 is a plan view of the cylinder body. , FIG. 3.

FIG. 4 is a cross-sectional plan view and bottom view of the cylinder head, FIG. 5 is a plan view of the valve mechanism of the engine of this embodiment, and FIG.
FIG. 7 is a sectional view taken along the line V[-VI in FIG. 5.

Fig. 8 is a right side view of a motorcycle equipped with the engine of this embodiment. In addition, Fig. 2, 5th to 8th
In the drawings, the right side in the drawing, the upper side in the drawing, and the left side in the drawing in FIG.

In the figure, reference numeral 1 denotes a motorcycle on which the engine of this embodiment is mounted, and the body frame 2 of the motorcycle 1 includes one main vibrator 2b at the upper and lower parts of the head vibrator 2a,
This is a so-called diamond-shaped structure in which the front end of the down tube 2C is welded and the upper end of the seat pillar 2d is welded to the rear end of the main vibe 2b. In addition, 2g is an under guard that protects the crankcase, 2e is a support pipe for suspending the engine with a frame extending between the main pipe 2b and the down tube 2C, and 2f is a seat rail.

A front fork 3 that pivotally supports a front wheel at its lower end is pivotally supported on the hend pipe 2a so as to be steerable left and right, and a rear arm 5 that pivotally supports a rear wheel 4 at the seat pillar 2d is pivoted up and down on the seat pillar 2d. It is pivoted for free movement. Further, this rear arm 5 is connected to the vicinity of the rear end of the main pipe 2b via a link mechanism (not shown) and one silk absorber 8. In addition, 6 is a fuel tank, 7 is a seat, 9a is an air scoop that covers the side of the tank, 9b is a side cover that covers the lower part of the seat, and 9C is a rear cover that covers the rear part of the vehicle.

An engine suspension (10) is suspended within the vehicle body frame 2. This engine unit 10 is a water-cooled four-stroke single-cylinder engine, and has a structure in which a cylinder body 12, a cylinder head 13, and a head cover 14 are stacked on the front upper surface of a crankcase 11 with a slight forward tilt. . One combustion chamber wall surface 13a is recessed approximately in the center of the lower surface of the cylinder head 13. The wall surface 13
The combustion chamber 15 is constituted by a and the head of a piston (not shown) which is slidably inserted into the cylinder liner 12a of the cylinder body 12. A plug screw hole 13b for attaching a spark plug is formed approximately in the center of the combustion chamber wall surface 13a, and the plug screw hole 13b is connected to the cylinder head 13.
．． A plug insertion hole 13c formed in the head cover 14,
14a leads out to the outside so as to be inclined toward the exhaust side (front side) with respect to the cylinder axis. Further, a spark plug 16 is screwed into the plug screw hole 13b. Furthermore, the plug insertion hole 13c has left and right drain holes 1.
3j and 13i are in communication with each other, and the left drain hole 13j is led out to the outer wall of the chain chamber 13h via a connecting pipe 13k. Note that, of course, either one of the left and right drain holes 13j and 131 may be provided.

The left, center,
The right intake valve opening 17.18.19 is on the other side, the left on the periphery,
A right exhaust valve opening 20.21 is formed, and the plug insertion hole 13c extends upwardly between the left and right exhaust valve openings 20.21. The left intake valve opening 17 is led out to the rear wall of the cylinder head by a left intake boat 22 that extends toward the rear of the vehicle so as to be substantially perpendicular to the axis of a camshaft 42 (described later) in plan view, and is connected to the center and right intake valve openings. 18 and 19 are led out rearward by a central intake boat 23a extending to the right in the vehicle width direction with respect to the camshaft 42, and a right intake boat 23b extending approximately at right angles, and the merging intake boat 23 of both intake boats 23a and 23b is As a whole, it extends to the right in the vehicle width direction. Above left intake boat 22. A carburetor 26 is connected to the rear end opening of the merging intake boat 23 via a carburetor insert 24 .

In addition, the left and right exhaust valve openings 18.19 are the left and right exhaust ports (28.2) that extend toward the front of the vehicle while expanding in a V-shape.
9 to the front wall of the cylinder head, and left and right exhaust pipes 31 and 32 of the exhaust system 230 are connected to the front end openings 28a and 29a of each port. This second prayer pipe 31
．． 32 passes through the left and right sides of the down tube 2C, bends to the right, merges here, and extends toward the rear of the vehicle, with a muffler 33 that also serves as a backstay at the extended end.
is connected.

The left, center, and right intake valve openings 17.18°19 have left, center, and right intake valves 34°35.36 that open and close them.
The left and right exhaust valve openings 20.21 have left and right exhaust valves 37.3 which open and close the valve plates 34a, 35a and 36a, respectively.
Eight valve plates 37a and 38a are arranged, respectively. The valve stems 34b to 38b of the multi-valves 34 to 38 are connected to the respective intake air,
It penetrates the ceiling walls of the exhaust boats 22.23a, 23b, 28.29 and protrudes upward from the mating surface of the rad 13 to the cylinder.

Here, the valve rods 37b and 38b of the exhaust valves 37 and 38 are perpendicular to the camshaft 42, that is, parallel to each other, when viewed from above, and are inclined forward at the same angle when viewed toward the cam wheel 42. overlap each other. Each exhaust valve 37.
38 is adapted to close the openings 20° 21 by a biasing spring 41 interposed between an upper stopper 39 fixed to the upper end thereof and a lower stopper 40 disposed on the spring seat of the cylinder body 13. Forced.

Further, the valve stems 34b to 36b of each of the intake valves 34 to 36 are also perpendicular to the camshaft 42 in plan view, and when viewed in the camshaft direction, the left and right intake valves 34 and 36 are similar to the exhaust valves 37 and 38. They are inclined backward at approximately the same angle and overlap each other. Also, the valve stem 35b of the central intake valve 35 is the left and right intake valve 34.36.
It is placed in a more upright position than the And above left.

The upper ends of the right valve stems 34b and 36b are the valve stems 35 of the middle intake valve 35.
located above the upper end of b, and these rings MA
, B's intersection C is located at a high place on the left.

It is located further above the upper ends of the right valve stems 34b and 36b. Moreover, each of these intake valves 34 to 36 is on the upper side.

It is biased in the closing direction by a biasing spring 41 interposed between the lower stoppers 39 and 40.

Further, the camshaft 42 is disposed so as to cross a position between the intake and exhaust valves and slightly offset from the cylinder axis toward the intake valves. This camshaft 42 has its left and right end portions and central portion supported by left and right cam bearings and central cam bearings.

It is composed of lower right bearings 13d and 13f, and upper left and right bearings (not shown) formed at the mating surface of the head cover 14. Further, the central cam bearing 73 is connected to the cylinder head 13.
The lower center bearing 13e formed in the center of the head cover 1
4, and this upper center bearing 14b is located on the left intake cam 42b side from the cylinder axis in order to avoid interference with a boss portion 52C of the right intake rocker arm 52, which will be described later. It is slightly deviated.

Note that 43 is a cam sprocket fixed to the left end of the camshaft 42, and 44 is an automatic decompression device that reduces the starting torque by appropriately releasing compression pressure near the compression top dead center.

Here, the left, right, and center cam bearings are of a two-piece type, and are fixed by fixing the head cover 14 to the cylinder head 13, but the head cover 14 and the cylinder head 13 are The peripheral edge of the opening, each of the cam bearings, and both edges of the plug insertion port 13 are fixed with fixing bolts (shown with hunting in FIG. 5), on the intake side of the peripheral edge of the opening. Regarding the flange portion 14 formed on the inside of the two locations between each of the above-mentioned intake valves.
h is fixed with a fixing bolt 50b.

Note that this fixing bolt 50b faces outward when the carriage 57 is removed. Furthermore, 50 of the fixing bolts are used both for the fixing and for preventing rotation of the Ronca shaft, which will be described later. However, 50c is a dedicated bolt for preventing rotation.

Between the camshaft 42 and the left and right exhaust valves 37 and 38, left and right exhaust rocker shafts 46g and 46b are disposed parallel to the camshaft 42, and are integrally formed on the inner surface of the head cover 14. It is supported by the bearing portion 14e and prevented from rotating by the fixing bolt 50. These left and right exhaust rocker shafts 46a.

Left and right intake rocker arms 47, 48 are swingably supported by 46b. Each rocker arm 47.48
are located on both sides of the plug insertion hole 13C, and are arranged in a V-shape that is wider on the camshaft side. Also, sliding portions 4 formed at the rear ends of the left and right intake rocker arms 47° 48
7a and 48a are the left and right lower cam bearings 1 of the cam fi42.
3d, left and right exhaust cams 42a formed inside 131,
42d, and the lower ends of adjustment screws 49 screwed into the front ends 47b, 48b are in contact with the upper ends of the left and right exhaust valve rods 37b, 38b.

Further, between the camshaft 42 and the intake valves 34 to 36, an intake port hook shaft 45 having a length spanning the left and right cam bearings is arranged parallel to the camshaft 42, and the rocker shaft 45 is connected to the camshaft 45. Both end portions and the center portion are supported by bearing portions 14f integrally formed with the head cover 14, and are prevented from rotating by the fixing bolts 50. The left intake port 7 arm 51 is pivotally supported on the left side of the lower central cam bearing 13e of the rocker shaft 45, and the center and right intake rocker arms 52, 64 are pivotably supported on the right side of the rocker shaft 45. Rocker arm 51.52.64 is left, right exhaust rocker arm 47.4
It is located between 8. The sliding portion 51a formed at the front end of the left intake port 7 arm 51 is in sliding contact with the left intake cam 42b formed on the left side of the central lower cam bearing 136 of the camshaft 42, and is threaded onto the rear end 51b. The lower end of the inserted adjustment screw 53 is in contact with the upper end of the left intake valve rod 34b. Also, the above center and right intake rocker arm 52.6
The sliding portions 52a and 64a formed at the front end of the center and right intake cams 42c are formed next to the right side of the center lower cam bearing 13e of the camshaft 42, respectively.

It is in sliding contact with 42e. Also, both intake rocker arms 52
．． Adjustment screws 54 and 53 screwed into the rear ends 52b and 64b of 64 are connected to the center and right intake valve rods 35b and 36.
It is in contact with the upper end of b.

The upper ends of the central intake valve rod 35b are the left and right intake valve rods 3.
It is located above the upper ends of 4b and 36b when viewed in the camshaft direction, and at the rear when viewed in the cylinder axial direction.

In other words, the plane projected distance M12' from the rocker shaft 45 to the upper end of the valve stem 35b of the central intake valve 35 is the left and right intake valves 34.3.
It is longer than the plane projection distance 11' of No. 6. Therefore, the arm length I12 (vertical distance from the rocker axis to the axis A) of the central intake valve 35 is also longer than the arm length ll of the left and right intake valves 34 and 36.

Furthermore, two adjustment ports 14c are formed on the exhaust valve side of the head cover 14 for adjusting the adjustment screws 49 of the left and right exhaust valves 37 and 38, and these can be opened and closed using separate caps 56. It has become. Further, one adjustment port 14d for adjusting the adjustment screws 53, 54 of each of the intake valves 34 to 36 is formed on the intake valve side, and this can be opened and closed with one cap 57.

Further, the cylinder body 12 has a cylinder liner 12a.
An annular water cooling jacket 60 is formed surrounding the cylinder head 1 (see Fig. 2), and the jacket 60 has communication holes 60a formed at a predetermined pitch on the mating side of the jacket 60, and a cylinder head 1.
The water cooling jacket 77a of the cylinder head 13 is connected to the water cooling jacket 77a of the cylinder head 13 through a communication hole 77d formed on the joint surface of No. It's communicating.

Here, the crank case 11 and the cylinder body 12 are connected, and the cylinder body 12 and the cylinder head 1 are connected.
The combination with 3 will be explained in detail. First, cylinder body 1
2 and the cylinder head 13, flange portions 82a are bulged at four locations on the circumference of the cylinder head 13, and four head bolt holes 8 are formed in the flange portions 82a.
2b and two head bolt holes 82b are formed in the chain chamber 13h side portion, and each bolt hole 82b is
Insert the head fixing bolt 63 into the cylinder body 12, and insert the lower part of the bolt 63 into the screw hole 12d formed in the upper part of the cylinder body 12.
This is done by screwing it into the

Furthermore, for coupling the crankcase 11 and the cylinder body 12, four cylinder bolt holes 12e are formed in the cylinder body 12 by penetrating from the upper mating surface 12f to the lower mating surface 12g of the cylinder body 12, and each of the port holes 12c
Insert the cylinder fixing bolt 62 into the cylinder, and insert the lower part of the bolt 62 into the screw hole 11 formed in the crankcase 11.
This is done by screwing into a. Here, each of the cylinder bolt holes 12c is located adjacent to the left and right head fixing bolt holes 12d (see Figure 2), and when viewed in a direction perpendicular to the cylinder axis, the cylinder bolt holes The upper part of 12c overlaps with the above-mentioned perforated hole i2d.

Further, a bolt head accommodating recess 12b is formed at the upper end of each of the cylinder bolt holes 12C, and the head 62a of the fixing bolt 62 is located within the recess J2b. Here, when looking in the direction of the cylinder axis, the above-mentioned cylinder bolt hole 1
2C is located at a position where a part of the head accommodation recess 12b overlaps with a part 60b of the water-cooled salmon and Toro 0, that is, this cylinder bolt hole 12c is arranged as close to the inner circumferential side of the cylinder body 12 as possible. This means that it has been done.

A sealing gasket 61 is interposed between the cylinder body 12 and the cylinder head 13. This gasket 61 is made of a metal plate such as stainless steel, has the same shape as the upper surface 12f of the cylinder body 12, and corresponds to each of the bolt holes and the communication hole 60a from the water-cooled jacket 60. There is an opening in the part. Further, this gasket 61 is formed with a bead to ensure sealing performance. These beads are in the shape of a convex strip, with an inner bead 61a located inside the communication hole 60a and an outer bead 61 located outside the communication hole 60a.
b, and the chain chamber bead 61 along the periphery of the chain chamber 12e.
e and a bolt bead 61d surrounding the outside of each bolt hole are continuous.

Next, the effects of this embodiment will be explained.

In the engine of this embodiment, the cylinder bolt hole 12C is formed in the cylinder body 12 so as to penetrate between the upper and lower mating surfaces 12f and 12g. The cylinder body 12 and the crankcase 11 are tightened compared to the conventional structure in which the flange portion formed in the cylinder body 12 and the crankcase 11 are tightened.
The rigidity of the connection can be greatly improved.

Further, since the cylinder fixing bolt 62 is placed close to the head fixing bolt 63 and a portion of both are overlapped in the height direction, the cylinder body 12. The cylinder head 13 is connected to the crankcase 1 by one continuous bolt.
1 to the crankcase 11, so that the crankcase 11. The overall joint rigidity of the cylinder body 12° and the cylinder head 13 can also be improved.

Furthermore, a part of the bolt head accommodating recess 12b formed at the upper end of the bolt hole 12 is connected to a water cooling jacket 60.
60b, the cylinder fixing bolt 62 can be brought as close to the inner peripheral side of the cylinder as possible, and the amount of outward bulge of the boss portion for the cylinder bolt hole 12c can be suppressed. The cylinder body 12 can be made smaller compared to the case where the flange is formed.

In addition, in the above embodiment, the cylinder body fixing bolt 6
A recess 12b for accommodating the head 62a of the cylinder head 13 is formed on the cylinder body 12 side.
It may be recessed on the side.

Furthermore, although the above embodiments have been explained using a four-stroke engine, the present invention can also be applied to a two-stroke engine.

[Effects of the Invention] As described above, according to the cylinder body coupling structure for a water-cooled engine according to the present invention, the bolt holes of the cylinder body are formed to penetrate the cylinder body, and the entire cylinder body is tightened. This has the effect of improving the rigidity of the connection between the cylinder body and the crankcase, and since the bolt hole is formed so that a part of the bolt head accommodating recess overlaps with a part of the water cooling jacket when looking at the bolt hole in the cylinder axial direction, the bolt The amount of outward bulge of the hole boss portion is suppressed, and it is possible to avoid increasing the size of the cylinder body.

[Brief explanation of drawings]

1 to 8 are diagrams for explaining a cylinder body coupling structure of a four-stroke engine according to an embodiment of the present invention, in which FIG. 1 is a cross-sectional side view thereof, and FIG. 2 is a plan view of the cylinder body. , FIG. 3. FIG. 4 is a cross-sectional plan view of each cylinder head. 5 is a plan view of the valve mechanism portion of the engine of this embodiment, FIGS. 6 and 7 are a sectional view taken along the line Vl-Vl of FIG. 5, a sectional view taken along the line VW-■, and FIG. 8, respectively. is a right side view of a motorcycle equipped with the example engine. In the figure, 10 is the engine, 11 is the crankcase,
12 is the cylinder body, 12C is the cylinder bolt hole, 1
2b is a bolt head housing recess, 13 is a cylinder head, 60
is a water cooling jacket, 62 is a cylinder fixing bolt, 62a
is the bolt head.

Claims (1)

[Claims] (1) In a cylinder body connection structure for a water-cooled engine, in which fixing bolts are arranged on the outside of a water cooling jacket formed around the cylinder, and the cylinder body is tightened and fixed to the crankcase by the fixing bolts, the fixing bolts are A bolt head accommodating recess in which the head is positioned is opened in the cylinder body or the cylinder head on the mating surface thereof, and a part of the accommodating recess is formed so as to overlap with the water cooling jacket when viewed in the cylinder axis direction. cylinder body connection structure for water-cooled engines.