CN1103852C - Structure of cylinder head of IC engine - Google Patents

Abstract

A cylinder head structure of an internal combustion engine which is a double overhead cam internal combustion engine having a plurality of intake valves and exhaust valves and a camshaft for the intake valves and a camshaft for the exhaust valves. Wherein, inside the bearings 43L, 43R, bearings 44L, 44R supporting the above-mentioned two camshafts, cylinder head fastening portions 46La, 46Ra, 47La, 47Ra, and make the joint surfaces of the cylinder head fastening parts 46La, 46Ra, 47La, 47Ra and the cylinder head mounting surface 4a the same plane. In this way, the processing of the cylinder head can be facilitated, the vibration can be suppressed, and the structure of the internal combustion engine can be compacted.

Description

Cylinder head construction of an internal combustion engine

technical field

The present invention relates to a cylinder head structure of a double overhead camshaft internal combustion engine.

Background technique

2 The overhead cam internal combustion engine has a camshaft for the intake valve and a camshaft for the exhaust valve on the cylinder head. In this 2 overhead cam internal combustion engine, a plurality of valves are arranged on the cylinder head, There are at least 2 bearings on the shaft, and a drive mechanism for driving the camshaft is required, so that there is little room for downsizing the internal combustion engine, and the arrangement of the fastening parts used to fasten the cylinder head to the cylinder and crankcase becomes question.

The invention described in Japanese Unexamined Patent Publication No. 8-177515 as an example of a conventional double overhead camshaft internal combustion engine is shown in FIG. 16 .

16 is a cross-sectional view of the intake side of the cylinder head structure of the internal combustion engine 01. The cylinder head 02 is covered with a cylinder head 03 via a gasket 04 to form a valve chamber.

A camshaft (not shown) is rotatably supported by left and right bearings 05, 06, and a sprocket 07 is provided at the end of the camshaft protruding from one bearing 05 to constitute a cam drive mechanism.

Cavities 08 , 09 for accommodating valve lifters of intake valves are formed side by side inside the left and right bearing portions 05 , 06 of the cylinder head 02 .

Fastening parts 010 and 011 are formed below the respective bearing parts 05 and 06 at partially overlapping positions, and stud bolts 012 and 013 are inserted to fasten the cylinder head 02 together with the cylinder to the crankcase.

When installing the cylinder cover 03, its upper wall is in contact with the bearing part 06, and the two are fastened by the bolt 014.

Since the sprocket 07 is provided outside the bearing portion 05 supporting the camshaft to form a drive mechanism, the cam drive system has a structure protruding to the outside, and the overall size of the internal combustion engine is increased.

In the cylinder head 02 , since the cylinder head fastening portions 010 and 011 are located below the joint surface with the cylinder cover 03 , spot facing is required during manufacture, which increases the cost.

When the cylinder head fastening part is located below the joint surface with the cylinder cover 03, interference with the valve lifter becomes a problem, and it is necessary to avoid the chambers 08 and 09 for housing the valve lifters in the bearing part as in the above example. Under 05 and 06, some measures such as fastening parts 010 and 011 are provided at the positions overlapping up and down, so that the cylinder head is enlarged.

In addition, since the upper wall of the cylinder head 03 is attached to the bearing portion 06 of the camshaft by the bolts 014, the vibration of the camshaft is easily transmitted to the cylinder head 03.

Contents of the invention

The present invention has been made in view of the above problems, and an object of the present invention is to provide a cylinder head structure of an internal combustion engine that is easy to process, can suppress vibration, and can realize a compact internal combustion engine.

In order to achieve the above object, the present invention provides a cylinder head structure of a 2 overhead cam type internal combustion engine, which has a plurality of intake valves and exhaust valves, and a camshaft for intake valves and a camshaft for exhaust valves, Its cylinder head structure is characterized in that: bearings are provided to respectively support both ends of the camshaft for the intake valve and the camshaft for the exhaust valve; the space between the bearing on the side of the intake valve and the intake valve; The space between the bearing on the exhaust valve side and the exhaust valve (and in the space between the camshaft for the intake valve and the camshaft for the exhaust valve) is provided with a cylinder head fastening portion; The joint surface of the fastening portion of the cylinder head is in the same plane as the cylinder head mounting surface provided on the upper surface of the cylinder head.

Since the cylinder head fastening portion is provided inside the bearings supporting the two camshafts, the overall size of the internal combustion engine can be reduced.

Since the joint surface of the cylinder head fastening part is flush with the cylinder head mounting surface, spot facing processing is not required, and processing can be completed with a small number of processing man-hours, which can reduce costs.

Since the fastening portion of the cylinder head is on both sides of the plurality of valves, and the fastening joint surface is on the same plane as the cylinder cover mounting surface, it will not interfere with the chamber for accommodating the valve lifters.

According to the second feature of the present invention, in the cylinder head structure of the internal combustion engine of the first feature, a pair of bearings are provided at both ends of the camshaft, and a cam driving mechanism is provided between one of the bearings and the fastening portion of the cylinder head. .

Since the cam drive mechanism is provided inside the bearing, the cylinder head can be miniaturized.

According to a third feature of the present invention, in the cylinder head structure of an internal combustion engine according to the first feature or the second feature, the cam drive mechanism is composed of a cam gear provided on each of the camshafts and a cam gear provided on the intermediate shaft for driving the cam gear. drive gear composition.

Since the cam drive mechanism has a compact structure in which the drive gear meshes with the cam gear, the cylinder head can be miniaturized.

According to a fourth feature of the present invention, in the cylinder head structure of the internal combustion engine according to the first feature, a cylinder cover is provided inside the pair of bearings and outside the camshaft for the intake valve and the camshaft for the exhaust valve. installation department.

Since the cylinder head mounting part is located outside the camshaft for the intake valve and the camshaft for the exhaust valve. It is arranged inside a pair of bearings without interfering with the above-mentioned cylinder head fastening portion, so it is not necessary to increase the width of the internal combustion engine in the direction of the camshaft, and since the cylinder cover is installed separately from the bearings, the vibration of the camshaft is not easy passed to the cylinder head.

Description of drawings

Fig. 1 is a right side view of an internal combustion engine according to an embodiment of the present invention.

Fig. 2 is a right sectional view of the internal combustion engine shown in Fig. 1 .

Fig. 3 is a left side view of the internal combustion engine shown in Fig. 1 .

Fig. 4 is a left sectional view of the internal combustion engine shown in Fig. 1 .

Figure 5 is a bottom view of the cylinder.

Figure 6 is a top view of the cylinder.

Fig. 7 is a left side view of the cylinder.

Fig. 8 is a sectional view taken along line VIII-VIII in Fig. 6 .

Fig. 9 is a sectional view taken along line IX-IX in Fig. 6 .

Fig. 10 is a sectional view taken along line X-X in Fig. 7 .

Fig. 11 is a plan view of a state in which a valve train is attached to a cylinder head.

Figure 12 is a side view of the cam box.

Figure 13 is a bottom view of the cam box.

Fig. 14 is a sectional view taken along a plane including the intermediate shaft.

Fig. 15 is a sectional view taken along a plane including the camshaft.

Fig. 16 is a sectional view showing a conventional cylinder head structure.

Detailed ways

An embodiment of the present invention will be described below with reference to FIGS. 1 to 15 .

The internal combustion engine 1 of the present embodiment is a 2 overhead camshaft type single-cylinder 4-stroke internal combustion engine, and two valve camshafts for the intake valve and the exhaust valve are provided above the cylinder, and its overall right side view and right sectional view are as follows As shown in Figure 1 and Figure 2, the left side view and left sectional view are shown in Figure 3 and Figure 4.

The internal combustion engine 1 is roughly divided into a crankcase 2, a cylinder 3, a cylinder head 4, and a cylinder cover 5, which are superimposed and assembled in this order upwards and slightly inclined forward.

The crankcase 2 supports the crankshaft 10 pointing to the left and right horizontal direction in a pivoting manner, and forms a transmission chamber behind it. As shown in FIG. Arrangement, the subshaft 15 is arranged obliquely behind the main shaft 11 and arranged in a form that can transmit power through the gear group.

Also, an oil pump 16 is disposed below the crankshaft 10 and is driven by meshing gears 12 and 17 .

An AC generator 19 is provided at the left end of the crankshaft 10 (see FIG. 3 ).

As shown in Figure 1, an oil filter 18 is arranged in front of the crankshaft 10 to purify the oil supplied from the oil pump 16 through the oil passage A1, and then send it to the crankshaft 10 through the oil passage A2, and pass through the oil filter formed in front of the right crankcase 2. The oil passage A3 of the side peripheral wall and the oil passage A4 leading from the oil passage A3 to the joint surface of the cylinder 3 rise in the cylinder 3, the cylinder head 4 after the joint surface of the cylinder 3 branches to the intake side and the exhaust side, Oil is supplied to the valve train.

Fig. 5 shows the joint surface 3a of the cylinder 3 and the crankcase 2, which is integrally cast as a cylinder liner 20 at a substantially central position slightly to the right. The long dimension of the generally rectangular chain passes through the hole 21 .

Stud bolt holes 22L, 22R, 23L, 23R are formed at the four corners of the joint surface 3a around the cylinder liner 20, and the rear side (upper side in FIG. The intake side stud hole 22R of the front side (lower side in FIG. A5.

That is, at the joint surface 3a between the cylinder 3 and the crankcase 2, the opening of the above-mentioned oil passage A4 of the crankcase 2 is located at a position on the right side of the cylinder liner 20, and branches from this position to the intake side stud hole 22R. , The columnar bolt holes 23R on the exhaust side (that is, the oil passages A5, A5) form the oil grooves 3b, 3b.

Therefore, the oil sent to the cylinder side from the oil passages A3 and A4 of the crankcase 2 branches to the front and back at the joint surface 3a, passes through the oil grooves 3b and 3b, and then ascends and is supplied in the oil passages A5 and A5 serving as stud bolt holes. to cylinder head 4 side.

In addition, a bolt hole 24 is provided at the left center of the rectangular chain passage hole 21 on the joint surface 3a of the cylinder 3, and a cylinder side bolt 25 passes through the bolt hole 24 to fix the left side of the cylinder 3 to the crankcase 2.

As shown in FIG. 2 , the cylinder head 4 superimposed on the cylinder 3 extends rearward from the two intake holes of the combustion chamber 30 facing the cylinder bore on the joint surface with the cylinder 3 to form intake passages 31 and 31 respectively. , respectively extending forward from the two exhaust holes to form exhaust passages 32 and 32 . A pair of left and right intake valves 33 , 33 of the valve body facing each intake port are inclined obliquely rearward, and valve lifters 33 a , 33 a are inserted into chambers 38 , 38 and slidably supported. Similarly, a pair of left and right exhaust valves 34, 34 of the valve body facing each exhaust hole are inclined obliquely forward, and valve lifters 34a, 34a are inserted into chambers 39, 39 to be slidably supported. Each valve 33, 33, 34, 34 is urged upward by a spring so that the valve body closes the holes.

Two air intake passages 31, 31 are assembled and connected to the rear carburetor 36 through a connecting pipe 35, and two exhaust passages 32, 32 are connected to the exhaust pipe respectively.

In addition, an ignition part of a spark plug 37 fitted from above is exposed at the center of the combustion chamber 30 .

As shown in the top view in FIG. 6, the upper part of the cylinder head 4 is formed in a substantially rectangular shape, and a chain insertion hole 41 is formed on the left side and a recess 42 recessed from the right side to the installation position of the spark plug 37 at the center, and the peripheral edge is used as a joint. The surface 4a constitutes the lower half of the valve chamber with the interior recessed.

The valve chambers on the upper part of the cylinder head 4 are symmetrically formed forward and backward with respect to the centerline passing through the installation position of the spark plug 37, the rear side is the intake side valve chamber 60, and the front side is the exhaust side valve chamber 61, inside the intake side valve chamber 60 The left and right protruding bearing portions 43L, 43R, and the left and right protruding bearing portions 44L, 44R in the exhaust side valve chamber 61 have the same height on the upper end surface as the joint surface 4a.

As shown in FIG. 11, the bearing parts 43L, 43R (see FIG. 6) on the left and right sides of the exhaust side valve chamber 60 support both ends of the intake camshaft 62 freely rotatably through bearings 64L, 64R, and the bearings 64L, 64R clamp It is held between the bearing portions 43L, 43R and the left cam frame 66 and the right cam frame 67 .

Similarly, the bearing portions 44L, 44R (see FIG. 6 ) on the left and right sides of the exhaust side valve chamber 61 rotatably support both ends of the exhaust camshaft 63 via bearings 65L, 65R. Between 44R and the left cam frame 68 and the right cam frame 69.

In addition, between the left bearing portion 43L and the bearing portion 44L positioned at the front and rear of the cylinder head 4, a round hole 45L horizontally penetrating through the chain insertion hole 41 from the left side of the cylinder head left and right is formed on the wall surface of the chain insertion hole 41. The circular hole 45R having a smaller diameter coaxial with the circular hole 45L is fitted with the intermediate shaft 70 from the left side in the circular hole 45L, 45R to be mounted on the chain insertion hole 41 (see FIG. 14 ).

The intermediate shaft 70 is composed of a large-diameter portion 70a fitted in the circular hole 45L and a small-diameter portion 70b fitted in the circular hole 45R. A tool hole 71 penetrating in the diameter direction is formed in the large-diameter portion 70a. A threaded hole 72 parallel to the tool hole 71 is also formed at the end of the portion 70b.

In the top view of the cylinder head 4 in FIG. 6 , bolt threads for attaching the cam frame are formed on the front and rear upper end faces of the bearings 43L, 34R of the intake camshaft 62 and the bearings 44L, 44R of the exhaust camshaft 63 . The holes 43La, 43Ra, 44La, 44Ra, in which the intake side columnar bolt hole 46R is formed on the left side of the front side bolt hole 43Ra of the right side bearing portion 43R of the exhaust camshaft 62, and on the left side thereof to the right of the chain insertion hole 41 The intake side stud bolt holes 46L are squarely formed.

The left and right intake-side stud bolt holes 46L, 46R are positioned to sandwich the front of the chambers 38, 38 from both sides, and the valve lifters 33a, 33a of the intake valves 33, 33 are accommodated in the chamber 38 so as to be slidable up and down. , 38 middle.

Exhaust-side columnar stud holes 47L, 47R are formed at forward symmetrical positions of the intake-side columnar bolt holes 46L, 46R, and the exhaust-side columnar bolt holes 47L, 47R are also located between the left and right bearing portions 44L, 44R. The positions of the rear parts of the chambers 39, 39 for accommodating the valve lifters 34a, 34a of the exhaust valves 34, 34 are sandwiched between both sides.

The upper end opening surfaces of the four stud bolt holes 46L, 46R, 47L, 47R, that is, fastening joint surfaces 46La, 46Ra, 47La, 47Ra are on the same plane as the joint surface 4a with the cylinder cover 5 (see FIG. 8 ).

The four stud bolt holes 46L, 46R, 47L, 47R penetrate downward, are aligned with the stud bolt holes 22L, 22R, 23L, 23R of the cylinder 3, and communicate with each other.

The column bolt holes 46R, 47R on the right continue the oil passages A5, A5 of the cylinder 3 described above.

As shown in FIG. 9 , the intake-side stud bolt hole 46R on the right side forms an oil passage A6 branching obliquely before leaving the fastening joint surface 46Ra, communicating with the adjacent bolt hole 43Ra.

The same oil passage A6 is also formed in the exhaust side stud hole 47R.

Bolt threaded holes 48L, 48R are formed at positions approximately symmetrical to the intake side stud bolt holes 46L, 46R with respect to the camshaft 62 , and at positions substantially symmetrical to the exhaust side stud bolt holes 47L, 47R with respect to the exhaust camshaft 63 . Bolt threaded holes 49L, 49R are formed at the positions.

Bolt threaded holes 48L, 48R, 49L, and 49R are threaded holes for mounting the cylinder cover 5, and are located on the front and rear outer sides of the camshafts 62, 63 and inside the left and right bearings 43L, 43R and bearings 44L, 44R.

Bolt holes 50 , 51 for mounting the cylinder head 4 are drilled at the left side bearing portions 43L, 44L slightly to the right.

In addition, a bolt hole 52 is formed between the intake side stud bolt hole 46L and the exhaust side stud bolt hole 47L, and the bolt hole 52 penetrates to the circular hole 45R.

As shown in FIG. 7 , the left side of the cylinder head 4 forms a joint surface 4 b with the lower half of the side cover 6 , and bolt screw holes 53 are formed at four positions along the joint surface 4 b.

The above-mentioned intake valves 33, 33 and exhaust valves 34, 34 are installed on the cylinder head 4, and the above-mentioned intermediate shaft 70 is inserted into the circular holes 45L, 45R as shown in FIG. The bearing 73 rotatably supports the sprocket 74 integrated with the drive gear 75, and is disposed in the chain passing hole 41, and is screwed into the threaded hole 72 formed in the small-diameter portion 70b, and the belt passing through the bolt hole 52 is screwed. The flange bolt 55 fixes the intermediate shaft 70 .

Thus, the tool hole 71 pierced in the large-diameter portion 70 a of the intermediate shaft 70 is directed in a direction perpendicular to the joint surface with the cylinder 3 .

When assembling the above-mentioned cylinder 3 and cylinder head 4 into the crankcase 2, first screw and erect four stud bolts 80 in the bolt threaded holes formed at four positions on the joint surface of the crankcase 2 and the cylinder 3. , and then respectively align the cylinder 3 intake side stud bolt holes 22L, 22R and exhaust side stud bolt holes 23L, 23R with the four vertical stud bolts 80 and insert them, thereby inserting the gasket 81 therein. The cylinder 3 is superimposed, and the piston 27 is inserted into the cylinder liner 20. At this time, one end of the connecting rod 26 is supported on the crank pin of the crankshaft 10, and the other end is pivotally connected to the piston 27.

Then, a cylinder side bolt 25 is inserted into the bolt hole 24 on the left side of the cylinder 3, screwed into the threaded hole of the crankcase 2, and fastened in a temporarily fixed state (see FIG. 14 ).

Four stud bolts 80 pass through the stud bolt holes 22L, 22R, 23L, and 23R and protrude upward.

Next, align the intake-side stud bolt holes 46L, 46R and the exhaust-side stud bolt holes 47L, 47R of the cylinder head 4 with the four protruding stud bolts 80, and superimpose the cylinder head 4 on the cylinder through the sealing gasket 82. 3 on the joint surface.

Since the four stud bolts 80 pass through the stud bolt holes 46L, 46R, 47L, 47R and expose the upper threaded portion from the fastening joint surfaces 46La, 46Ra, 47La, 47Ra, the flanged nut 83 can be screwed to the upper threaded portion, And the cylinder 3 and the cylinder head 4 can be fastened while adjusting the relative position with respect to the crankcase 2 (see FIG. 2 and FIG. 11 ).

As shown in FIG. 14, just below the tool hole 71 of the intermediate shaft 70 erected on the cylinder head 4, there is a cylinder side bolt 25 temporarily fixed in advance. Since the head of the bolt is formed as a hexagonal hole 25a, the hexagonal A tool such as a wrench passes through the tool hole 71 from above, and the end is fitted into the hexagonal hole 25a of the head of the cylinder side bolt 25 to tighten the cylinder side bolt 25 and fix the left side of the cylinder 3 to the crankcase 2.

Bolts 84, 84 are respectively inserted into the bolt holes 50, 51 along the left side bearing portions 43L, 44L of the cylinder head 4, and screwed to the threaded holes of the cylinder 3, thereby fixing the left side of the cylinder head 4 to the cylinder. 3.

A chain 79 is suspended between the sprocket 74 supported by the intermediate shaft 70 and the driving sprocket 78 of the crankshaft 10 through the chain passage holes 21 and 41 (see FIG. 14 ).

The chain 79 is moderately tensioned by the chain tensioner 100 (see FIG. 4 ).

On the upper intake side valve chamber 60 and the exhaust system valve chamber 61 of the cylinder head 4 assembled in this way, the intake camshaft 62 and the exhaust camshaft 63 are installed as described above, and the two ends thereof are respectively passed through the bearing 64L, 64R, 65L, 65R are rotatably supported by left and right cam frames 66 , 67 , 68 , 69 .

In addition, fixed cam gears 76 and 77 are fitted to the left sides of the intake camshaft 62 and the exhaust camshaft 63 , respectively, so as to mesh with a drive gear 75 supported by the intermediate shaft 70 .

Align the front and rear bolt holes of the left and right cam frames 66, 67, 68, and 69 with the respective front and rear bolt threaded holes 43La, 43Ra, 44La, and 44Ra of the bearing parts 43L, 43R, 44L, and 44R. Solidly, both ends of the intake camshaft 62 and the exhaust camshaft 63 are rotatably supported.

Wherein, the cam frames 67 and 69 on the right side are of special shape, and the cam frame 69 on the exhaust side is shown in Fig. 1 and Fig. 13 .

The cam holder 69 is generally formed in the shape of a rectangular parallelepiped elongated in the front-rear direction, with a semicircular recess 69a formed on the left side, and a semicircular recess 69b with a smaller diameter formed on the bottom thereof, and the recess 69b is closed by the right side wall.

Bolt holes 69c and 69d are vertically formed in front and rear of the concave portion 69a. The bolt holes 69c and 69d penetrate the bottom surface, and on the joint surface 69e with the bearing portion 44R on the bottom surface, oil is formed along the half circumference of one bolt hole 69d. The groove 69f and the oil groove 69f extend to the above-mentioned small-diameter recess 69b.

That is, the bolt hole 69d communicates with the recessed portion 69b through the oil groove 69f.

The cam frame 67 on the intake side also has recessed parts 67a, 67b, bolt holes 67c, 67d, and oil groove 67f, and has the same structure.

Therefore, when the cylinder 3 and the cylinder head 4 are assembled in the crankcase 2, and the camshafts 61, 62 are supported by the cam frames 66, 67, 68, 69, the oil flowing through the oil channel A4 of the crankcase 2 is supported by the oil groove 3b. , 3b branches to the front and back, flows to the intake side and exhaust side, rises in the oil passages A5, A5 formed by the stud bolt holes 22R, 23R of the cylinder 3, and the stud bolt holes 46R, 47R of the cylinder head 4, and passes through The obliquely branched oil passages A6, A6 of the cylinder head 4 flow from the bolt threaded holes 43Ra, 44Ra of the bearing portions 43R, 44R to the bolt holes 67d, 69d of the cam frames 67, 69, and then flow to the recessed portion 67b through the oil grooves 67f, 69f. , 69b, as shown in FIG. 15, enter the in-shaft oil passages A7, A7 of the intake camshaft 62 and the exhaust camshaft 63 from the recesses 67b, 69b, and branch from the oil passages A7, A7 to a plurality of oil branch passages A8, supplied to the cam peripheral surface and the cam gears 76,77.

On the upper part of the cylinder head 4 at the joint surface 4a, the cylinder cover 5 is covered by the sealing gasket 86, and the four screw holes 48L, 48R, 49L, 49R on the upper wall of the cylinder cover 5 facing the bolt threaded holes 48L, 48R, 49L, 49R of the cylinder head 4 The position is formed with a bolt hole 88 and a circular fastening joint surface 89 around the bolt hole 88. As shown in FIG. The flanged bolt 91 is passed through the bolt hole 88 together with the mounting rubber 90 and screwed into the bolt threaded hole 48L, 48R, 49L, 49R of the cylinder head 4, and the cylinder cover 5 is mounted by floating fastening. on the cylinder head 4.

That is, the cylinder cover 5 is supported by the cylinder head 4 in a floating state via the gasket 86 and the mounting rubber 90 via the flanged bolt 91 screwed and fixed to the cylinder head 4 .

The left side wall of the cylinder cover 5 is connected with the joint surface 4a of the left side wall of the cylinder head 4 through a sealing gasket 86 (the part of the machining cutout at the position extending from the camshaft 62, 63 of a part of the cylinder head 4 is inserted into the installation and The left side of the gasket 86 integral cover portion 86a) forms a joint surface with the side cover 6 together with the joint surface 4b of the cylinder head 4, and bolt screw holes 92 are formed at four positions on the outer peripheral edge of the joint surface.

That is, the outer surfaces of the cylinder head 4 and the left side wall of the cylinder cover 5 integrally form a joint surface along the outer circumference thereof, and bolt screw holes 53 are formed at four positions on the cylinder head 4 side of the joint surface. , Bolt threaded holes 92 are formed at four positions on one side of the cylinder cover 5 .

The side cover 6 is put on the joint surface from the left side.

As shown in FIG. 3 , the side cover 6 is a flat cover consisting of a large central circular portion 6a and protruding circular portions 6b, 6c protruding forward and backward, and its bottom wall is surrounded by a peripheral wall 6d. Bolt holes 93 facing the eight bolt screw holes 53 and 92 are formed in the peripheral wall 6 d corresponding to the joint surfaces of the cylinder head 4 and the cylinder cover 5 .

Cover the side cover 6 on the left side of the cylinder 4 and the cylinder cover 5, and install a sealing gasket 94 between the joint surfaces, so that the bolt holes 93 are respectively aligned with the bolt threaded holes 53, 92, as shown in Figure 15. A cylindrical mounting rubber 95 with a flange formed at one end is inserted into the bolt hole 93, so that the flanged bolt 96 penetrates through it and is screwed into the bolt threaded holes 53, 92, and the side cover 6 is installed on the cylinder in a floating fastening manner. Cover 4 and cylinder cover 5.

That is, the flanged bolt 96 is screwed and fixed to the cylinder head 4 and the cylinder cover 5, and the flanged bolt 96 is used to attach the side cover 6 to the cylinder head 4 and the cylinder head 4 in a floating state through the gasket 94 and the mounting rubber 95. Cylinder cover 5.

In the side cover 6 mounted in this way, as shown in FIG. , S2 (referring to Fig. 4) is different, is in the position of biasing forward and backward.

The present internal combustion engine 1 is assembled as described above.

The intake camshaft 62 and the exhaust camshaft 63 are supported at both ends by the bearings 43L, 43R and 44L, 44R, and inside the left bearings 43L, 44L are a sprocket 74, a drive gear 75, and a camshaft gear 76. , 77 and other cam drive mechanisms, because the fastening joint surfaces 46La, 46Ra, 47La, 47Ra on the cylinder head 4 of the bolts 80 that fasten the cylinder head 4 and the cylinder 3 to the crankcase 2 together are arranged on the left and right bearing parts 43L , 43R and the inner sides of the left and right bearing parts 44L, 44R, so the left and right width of the cylinder head 4 can be reduced, and the internal combustion engine 1 as a whole can be compacted.

Since the fastening joint surfaces 46La, 46Ra, 47La, 47Ra of the cylinder head 4 are on the same plane as the joint surface 4a of the cylinder cover 5, there is no need for countersinking, which can reduce the processing workload and cost.

Since the fastening joint surfaces 46La, 46Ra, 47La, 47Ra and the joint surface 4a of the cylinder cover 5 are on the same plane, even if they are close to both sides of the chambers 38, 39 for accommodating the valve lifters 33a, 34a, the There is no interference with the chambers 38, 39, so that the internal combustion engine 1 can be downsized.

Since the bolt threaded holes 48L, 48R, 49L, 49R of the cylinder head 4 as cylinder cover mounting parts are outside the intake camshaft 62 and the exhaust camshaft 63, they are not fastened to the cylinder head joint surfaces 46La, 46Ra, 47La, 47Ra is arranged inside the left and right bearing parts 43L, 43R and the left and right bearing parts 44L, 44R so as to interfere, so that the internal combustion engine 1 can be downsized. 66, 67, 68, 69 are installed separately, so the vibration of the camshafts 62, 63 is not easily transmitted to the cylinder cover 5.

Claims (4)

1. the cylinder head structure of an internal-combustion engine, this internal-combustion engine are a plurality of intake valves and exhaust valve to be arranged and the 2 overhead camshaft type internal-combustion engines of intake valve with camshaft and exhaust camshaft are arranged; It is characterized in that:

Be provided with and support the bearing of aforementioned intake valve respectively with the two ends of camshaft and aforementioned exhaust camshaft;

In the space that bearing and aforementioned intake valve clipped of aforementioned intake valve one side and the space that bearing and exhaust valve clipped of aforementioned exhaust valve one side (and, aforementioned intake valve with the space that camshaft and aforementioned exhaust camshaft clipped in) the cylinder head engagement portion is set;

Making the mating face of aforementioned cylinder head engagement portion is same plane with the cylinder cover cap attachment face that is arranged on above the aforementioned cylinder head.

2. combustion engine cylinder head as claimed in claim 1 structure, it is characterized in that: pair of bearings is established at the two ends at above-mentioned camshaft, between this is to side of bearing and above-mentioned cylinder head engagement portion cam drive mechanism is set.

3. combustion engine cylinder head as claimed in claim 1 or 2 structure is characterized in that: cam drive mechanism is made of the camshaft gear wheel of being located at above-mentioned each camshaft and the actuation gear that is used to drive above-mentioned camshaft gear wheel of being located at jack shaft.

4. combustion engine cylinder head structure as claimed in claim 1 is characterized in that: in the inboard of above-mentioned pair of bearings, use the arranged outside cylinder cover cap assembly department of camshaft with camshaft and above-mentioned exhaust valve in above-mentioned intake valve.

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