JP4184218B2 - Internal combustion engine - Google Patents

Description

The present invention relates to an internal combustion engine that employs an OHC valve mechanism , and more particularly to a camshaft holder for a valve mechanism in the internal combustion engine .

As a swing arm type valve operating mechanism in an internal combustion engine adopting a conventional OHC type valve mechanism, a pivot part of a rocker arm is formed in the head part as a part of the structure of a cylinder head part. It is known that an oil passage for lubrication in a part is formed as a part of a structure part of the head part (see, for example, Patent Document 1).
Japanese Patent No. 2767453 (page 3-6, Fig. 1)

  As shown in FIG. 17, in the valve mechanism described in Patent Document 1, the intake / exhaust valve camshaft 050 is rotatable by a cam case 040a and a camshaft holder 040b coupled to the cam case. The cam action caused by the rotation of the intake / exhaust valve camshaft 050 is transmitted to the swing arm 060a via the intake / exhaust valve operation mode changing mechanism 060 (rocker arm) pivotally supported by the cylinder head 020. .

The movement transmitted from the intake / exhaust operation mode changing mechanism 060 to the swing arm 060a moves the intake / exhaust valves 030 that press the retainer 033 above each intake / exhaust valve 030 through the pivot movement by the valve head clearance eliminating mechanism 070 up and down. The intake / exhaust valve 030 is opened and closed, and the pivot portion 047a in the pivot motion for this purpose is substantially provided in the cylinder head portion 020.

As described above, in the valve operating mechanism described in Patent Document 1, the pivot movement in the swing arm is performed in the pivot portion formed in the cylinder head portion, and therefore, an oil passage for lubrication in the pivot portion. Is substantially formed in the cylinder head portion. Further, in this valve operating mechanism, the camshaft is supported by a cam case and a cam holder, and is provided by a so-called halved support portion.

Further, the formation of the pivot portion as described above and the oil passage for lubrication in the pivot portion in the cylinder head portion leads to complication of the structure of the cylinder head portion. The processing for forming the oil passage is difficult to perform, and the cost for the processing remains high.

In addition, since the cam shaft is supported by the support that has a half structure between the cam case and the cam holder, it is necessary to set the cam shaft on the cam case and then cover the cam holder when assembling the cam shaft. For this reason, there is still a problem that the support portion of the halved structure becomes co-processed and set flow, and management for the process for that purpose is required.

Therefore, in such a situation, in the arrangement of the valve operating mechanism as described above in the engine, the structure of the cylinder head portion is complicated, and an oil passage for lubrication in the cylinder head portion is formed. It is premised on difficulty and cost increase, etc., and it is easy to install the valve mechanism, easy to manage in processing and processing, and excellent in assembly of camshaft and rocker arm. There is a demand for an arrangement structure of the valve mechanism in the engine.

In order to solve the above-mentioned problem, the invention according to claim 1 is an internal combustion engine comprising a cylinder head, a camshaft, and a rocker arm that is driven by the camshaft to open and close the intake / exhaust valve device. A cam shaft holder provided separately from the cylinder head portion, and the cam shaft holder has a substantially rectangular outer shape when viewed in the axial direction of the cylinder head portion; The four bearing structure portions are integrally coupled by connecting portions extending along the substantially rectangular side surfaces, and the bearing structure portions facing each other in pairs are provided. The camshafts are rotatably supported, and the bearing structure portions facing each other in pairs are coupled by two connection structure portions crossing the camshaft holder, and the rocker arm is connected to each of the connection structure portions . Rocker Is formed integrally with over arm pivot receiving portion, the mounting seat surface to the cylinder head portion of the front Symbol camshaft holder, a cam shaft holder side fuel supply port connected to the filler opening of the oil supply passage in said cylinder head unit is formed The camshaft holder side oil supply port communicates with an oil passage in the camshaft holder.
According to a second aspect of the present invention, in the first aspect of the present invention, the mounting seat surface of the camshaft holder to the cylinder head portion is connected to one of the connection portions extending along the substantially rectangular side surface. The camshaft holder side oil supply port is formed.

In the invention according to claim 1, the camshaft holder has a substantially rectangular outer shape when viewed in the axial direction of the cylinder head portion, and has four bearing structure portions having four round shaft holes at four corners of the substantially rectangular outer shape. The four bearing structure portions are integrally coupled by connecting portions extending along the substantially rectangular side surfaces, and the cam shafts are rotatably supported by the bearing structure portions facing each other in pairs. The bearing structure portions facing each other in a pair are connected by two connection structure portions crossing the camshaft holder, and a rocker arm pivot receiving portion of the rocker arm is formed integrally with each of the connection structure portions. since that, before the mounting of the cam shaft holder to the cylinder head unit, since previously the rocker arm can set small in the cam shaft holder, yet it will be handled as a unit while having a cam shaft holder has four bearing structure, set Only property is improved. Further, the oil passage of the camshaft holder as a single unit is simplified.

According to the invention which concerns on Claim 2, the camshaft holder side oil supply opening to four bearing structure parts is formed using the connection part which connects a bearing structure part.

  A rocker arm pivot receiving portion of the rocker arm is integrally formed with the camshaft holder of the internal combustion engine.

An embodiment of the present invention will be described below with reference to FIGS.
FIG. 1 shows a cylinder upper structure of an internal combustion engine E in this embodiment. A crankcase (not shown), a cylinder block 10 coupled to the crankcase, and a cylinder head portion coupled to the cylinder block 10 are illustrated. 20 and a head cover HC coupled to the cylinder head portion 20.

As is well known, a crankshaft is rotatably supported in a crankcase (not shown) via a bearing portion, and a piston P is attached to a crankpin of the crankshaft via a connecting rod CR (not shown). ing. The cylinder block 10 coupled to the crankcase is provided with a cylinder hole 10a, and the piston P reciprocates in the cylinder hole 10a. A combustion chamber 21 is formed in a space formed by the upper portion of the cylinder hole 10 a of the cylinder block 10 and the lower portion of the cylinder head portion 20 coupled to the cylinder block 10.

In the combustion chamber 21, an opening 22a of the intake / exhaust port 22 is opened, and although not shown in FIG. 1, a spark plug faces, and the cylinder head portion 20 has an intake portion. An exhaust valve device 30 and an intake / exhaust port 22 are formed. The port 22 has an opening 22a opened in the combustion chamber 21 connected to the intake / exhaust port 22, and the intake / exhaust valve device. 30 opens and closes the opening 22a of the intake / exhaust port 22 opened in the combustion chamber 21 by the valve head 31 below the valve mechanism.

Further, a camshaft holder 40, a rocker arm 60, and the like for performing a swing arm type valve drive system, which is a characteristic structure in the embodiment of the present invention, are provided above the cylinder head portion 20.
The details of the structure of the cylinder head portion 20 and the structure of the valve operating mechanism, the camshaft holder 40, the rocker arm 60, etc. provided in the cylinder head portion 20 will be described below.

First, the structure of the cylinder head portion 20 will be described. FIGS. 2 to 5 show the detailed structure of the cylinder head portion 20.

FIG. 2 is a top view of the cylinder head portion 20, in which the cylinder head portion 20 having a rectangular outer shape is illustrated, and as can be understood from the drawing, an ignition not shown in the vicinity of the center portion is illustrated. An attachment hole 23 for the plug is opened, and in this embodiment, an opening for attaching the ignition plug is installed at a symmetrical position in the oblique direction for attaching a valve guide of an intake / exhaust valve device not shown in the drawing. A pair of holes 26 are opened.

Furthermore, a lubricating oil supply passage 24 is formed along the side surface 20A1 at a position near one side surface 20A1 of the two long side surfaces 20A1 and 20A2 in the outer shape similar to the rectangular shape of the cylinder head portion 20. Oil supply ports 24a and 24a for supplying oil are formed at both ends of the supply passage 24. A cooling fin F is provided on the outer surface of the one side surface 20A1.

3 is a cross-sectional view taken along the line AA in FIG. 2. As can be understood from FIG. 3, the spark plug mounting hole 23 is a hole penetrating from the upper part to the lower part of the cylinder head part 20, and the hole 23 is The large-diameter hole extending from the upper opening and the small-diameter hole extending to the lower opening 23a are connected to the large-diameter hole. Further, the lubricating oil supply passage 24 is shown here as a structure formed as a single groove on the head of the boss portion 25 protruding in a rib shape, and further provided on the outer surface of the one side surface 20A1 of the outer shape. A structure in which a plurality of cooling fins F are provided on the lower side is shown.

Incidentally, the cylinder head portion 20 is coupled to the cylinder block 10 as shown in FIG. 1 and as described above, and at the time of the coupling, the upper portion of the cylinder hole 10a of the cylinder block 10 and the lower portion of the head portion 20 are coupled. The space formed on the surface is the combustion chamber 21 described above. FIG. 4 shows a bottom view of the cylinder head portion 20, and the combustion chamber 21 is shown in a circular shape.

The combustion chamber 21 has an opening 23a of the center spark plug mounting hole 23 and a pair of intake / exhaust air for intake / exhaust disposed at a substantially symmetrical position obliquely oriented as described above across the opening 23a. An opening 22a of the port 22 is opened, and the opening 22a of the port 22 communicates with an intake / exhaust port 22 indicated by a dotted line as can be understood by referring to FIGS. The suction / exhaust valve device 30 shown in FIG.

  The opening 22a of the port 22 for intake / exhaust is provided with a valve head 31 when the pair of intake / exhaust valve devices 30 shown in FIGS. When the intake / exhaust valve device 30 is operated, the opening 22 a of the intake / exhaust port 22 is opened and closed by the valve head 31 of the valve device 30. 4 shows oil supply ports 24a and 24a for supplying lubricating oil, some of which are shown in FIGS. 2 and 3, and the cooling fin F is also shown.

As described above and as shown in FIGS. 1 and 5, a pair of intake / exhaust valve devices 30 are mounted in the cylinder head portion 20. The structure of the valve guide 27 mounting hole 26 for this purpose is illustrated in FIG. 4 can be clearly understood from FIG. According to FIG. 5, the pair of valve guide mounting holes 26, 26 have substantially the same structure and are provided so as to penetrate the cylinder head portion 20 with substantially the same inclination angle.

1 and 5, the valve guide mounting hole 26 is concentric with the opening 22a of the intake / exhaust port 22, which is the opening in which the valve head 31 of the hole 26 is disposed, and the opening 22a. And a hole 26 opening 26a at a position 22b in the vicinity of the opening 22a of the port 22 so as to intersect the intake / exhaust port 22 communicating with the opening 22a at a predetermined angle. A valve guide 27 having a through hole 28 into which the valve stem 32 is slidably fitted is fitted.

The valve device stem 32 is inserted into the through hole 28 of the valve guide 27 fitted in the hole 26 and the valve device 30 is mounted. When the valve device 30 is mounted, the valve stem end is mounted. The valve stem end 33 is inserted from the side of the opening 22 a of the intake / exhaust port 22 that opens to the combustion chamber 21, and the valve from the intake / exhaust port 22 close to the opening 22 a of the port 22. The stem end 33 of the valve stem 32 passes through the upper opening of the through hole 28 through the through hole 28 of the guide 27 and is inserted until the stem end 33 protrudes a predetermined length from the opening (see FIGS. 1 and 5).

As shown in FIG. 1, one end 67 of a rocker arm 60, which will be described later, is brought into contact with the stem end 33 at the upper end of the valve stem 32 protruding from the opening of the through hole 28 of the valve guide 27 with a slight gap. Further, a valve spring S is attached between a spring receiver 34 provided on the stem end 33 and a spring receiver 29 provided on the stem guide 27.

As will be described in detail later, the rocker arm 60 is oscillated by a cam operation caused by the rotation of the cam shaft 50 to move the valve stem end 33 up and down through its contact portion, thereby The valve head 31 at the lower end 32 opens and closes the opening 22 a of the intake / exhaust port 22. Accordingly, the appropriate mounting of the intake / exhaust valve device 30 is ultimately made by adjusting the operation of the rocker arm 60 having a structure that is in contact with the valve stem end 33.

The structure of the cylinder head portion 20 is generally as described above. As is apparent from the operation of the intake / exhaust valve device 30, and as described above, the cylinder head portion 20 has an upper portion for the operation. A rocker arm 60 and a cam shaft 50 provided with a cam 52 for swinging and driving the rocker arm 60 are disposed. The cam shaft 50 is supported by a cam shaft holder 40 shown in FIGS.

FIG. 6 shows a top view of the camshaft holder 40. According to the figure, the camshaft holder 40 has a substantially rectangular outer shape having long side surfaces 40A1 and 40A2 and short side surfaces 40B1 and 40B2 in the top view. The bearing structure portions 41, 42, 43, 44 are disposed at the four corners thereof, and these bearing structure portions face each other and other bearing structure portions at the side surface portion and the front portion thereof, and the facing portions. They are connected via connection portions 45, 45, 46 and 46, respectively, and as a result, the bearing structure portions 41, 42, 43 and 44 at the four corners are integrally coupled to each other.

That is, in the two short side surfaces 40B1 and 40B2 in the substantially rectangular outer shape, the two bearing structure portions 41 and 42 are connected by the connection portions 45 and 45 extending in the width direction of the holder 40 with their side surfaces facing each other. In other words, in FIG. 6, the right bearing structure portions 41, 42 and the left bearing structure portions 43, 44 are connected by connection portions 45, 45 extending in the width direction of the holder 40, respectively.

And these connection parts 45 and 45 include the part ranging from the upper part of bearing structure parts 41 and 42 and 43 and 44 to an outer side part, see side view (refer FIG. 7 etc.), and connection parts 45 and 45 which exhibit a substantially circular arc shape. The outer wall portions which are the short side surfaces 40B1 and 40B2 of the holder 40 are substantially formed by the substantially arcuate connection portions 45 and 45.

Shaft holes 41a, 42a, 43a, 44a are formed in the respective bearing structure portions 41, 42, 43, 44, and a pair of bearing structure portions 41, 42 that face each other and are connected to each other on the short side surfaces 40B1, 40B2. The shaft holes 41a, 42a and 43a, 44a in 43 and 44, that is, the two shaft holes 41a, 42a and 43a, 44a in the bearing structure part that forms a pair on the right side and on the left side are shown in FIG. As shown in FIG. 10 which is a directional view, the circular holes are concentric holes when viewed from the side, and these shaft holes 41a, 42a and 43a, 44a rotate the cam shaft 50 described later via a bearing. It is a shaft hole provided for possible support.

As can be understood from FIGS. 10, 11, 12 and the like, the inner diameters of the two shaft holes 41a and 42a and 43a and 44a of the bearing structure portions 41 and 42 and 43 and 44 to be paired are different. As shown in the figure, the holes 41a and 43a having a small inner diameter do not penetrate, and the shaft holes 42a and 44a having a large inner diameter are through holes. Partially enlarged portions 42a1 and 44a1 for insertion of 50 are provided (see FIG. 10).

And the cam shaft 50 demonstrated later is rotatably supported by shaft hole 41a, 42a and 43a, 44a which make two pairs via bearings, such as a ball bearing. Accordingly, the pair of cam shafts 50 and 50 supported by the shaft holes 41a and 42a and 43a and 44a cross between the side surfaces of the bearing structure portions 41 and 42 and between the side surfaces of the bearing structure portions 43 and 44. (See FIGS. 11 and 12).

Further, the bearing structure portions 41 and 43 and 42 and 44 that are opposed to each other and connected to each other on the two long sides 40A1 and 40A2 having a substantially rectangular shape, that is, the upper right bearing structure in FIG. Part 41 and left bearing structure part 43 are connected to each other via two thin connection parts 46 and 46 extending along the long side surfaces 40A1 and 40A2, respectively. The connecting portion 46 of the long side surface 40A1 connects the lower portions of the bearing structure portions 41 and 43 (see FIG. 7), and the connecting portion 46 of the long side surface 40A2 is connected to the bearing structure portion 42. 44 are connected to each other (see FIG. 10).

Further, two relatively thin structures that substantially cross the holder 40 from the vicinity of the base portion 46a of the connecting portion 46 on the long side surface 40A1 on the one side toward the opposing portion below the connecting portion 46 on the long side surface 40A2. The parts 47 and 47 are extended. The two structural portions 47 and 47 are provided with bearing portions having arcuate pivot receiving portions 47a and 47a, respectively. The bearing portions having the arcuate pivot receiving portions 47a and 47a are provided in the bearing portions having arcuate pivot receiving portions 47a and 47a. A spherical portion 71 of the pivot shaft 70 of the rocker arm 60 described later is supported.

  FIG. 8 shows a bottom view of the holder 40, which includes two connection portions 46, 46 extending along the long side surfaces 40 A 1, 40 A 2 of the outer shape of the holder 40 having a substantially rectangular shape. Two bearing structure portions 41, 43 and 42, 44 forming a pair are integrally connected to each other, and the bearing structure portion 41, which is paired by two connection portions 45, 45 extending along the short side surfaces 40B1, 40B2, respectively. The manner in which 42 and 43.44 are integrally connected to each other is shown.

  Further, in FIG. 8, one of the two connection portions 46, 46 extending along the long side surfaces 40 </ b> A <b> 1, 40 </ b> A <b> 2 of the holder 40, that is, the connection portion 46 on the long side surface 40 </ b> A <b> 1 side of the holder 48 is formed, and oil supply ports 48a, 48a for supplying oil are opened at both ends of the passage 48.

Of course, these two oil supply ports are substantially the same as the two oil supply ports 48a and 48a shown in FIG. 6 at the top, and the two oil supply ports 48a and 48a are provided by the holder 40. An opening serving as an oil supply source that communicates with an oil passage in the head portion 20 when attached to the cylinder head portion 20 and supplies lubricating oil into each passage of the holder 40 through the oil supply ports 48a and 48a. is there.

Further, FIG. 8 shows two thin connection structures that cross the width direction of the holder 40 between the base portion vicinity positions 46a of the two connection portions 46 and 46 extending along the long side surfaces 40A1 and 40A2 of the holder 40. 47 and 47 are illustrated, and between the connection structure portions 47 and 47 and the above-described arc-shaped connection portions 45 and 45 forming outer wall portions extending along the short side surfaces 40B1 and 40B2 of the holder 40, respectively, are substantially rectangular. A state in which a pair of shaped space portions 49, 49 is formed is illustrated.

By the way, as already described, since many oil passages for lubrication are formed in the holder 40, the oil passages in the holder 40 will be described here.

The above-described two oil supply ports 48a and 48a serving as oil supply sources in the holder 40 extend along the side surface 40A1 on one side of the long side surfaces 40A1 and 40A2 of the holder 40 as shown in FIGS. The narrow connecting portion 46 is formed in the vicinity of the base portion 46a, 46a to the left and right bearing structure portions 41, 43, and the two oil supply ports 48a, 48a are respectively formed in the cylinder head portion 20 as described above. The oil is supplied into the holder 40 through the communication between the ports 24a and 24a.

As shown in FIG. 10 , the two oil supply ports 48a and 48a extend in the thickness (height) direction of the holder 40 in the vicinity of the front wall portions of the two opposing bearing structure portions 41 and 43, respectively. through hole 48b penetrating 40, respectively, communicating with the 48b, the through-hole 48b, from middle position of 48b passage 48c which branches towards the shaft hole not penetrating the bearing structure 41, 43, 48c are formed, The branch passages 48c and 48c reach the inner peripheral surfaces of the shaft holes 41a and 43a that do not penetrate, respectively, and are opened.

Further, a passage 48 connecting the two oil supply ports 48a, 48a to the oil supply ports 48a, 48a is formed in a thin connecting portion 46 extending along the long side surface 40A1 of the holder 40, and the passage 48 is formed by the two oil supply ports. 48a and 48a are provided with branch passages 48d and 48d extending along the narrow connecting structure portions 47 and 47 that cross the width direction of the holder 40 from the positions in the vicinity of the holder 40, respectively. The branch passages 48d and 48d are the arcuate pivot receiving portions. The bearing portion having 47a and 47a is reached (see also FIG. 13 which is a cross-sectional view taken along the line EE in FIG. 6).

The two oil supply ports 48a and 48a are connected to a passage 48 formed in the thin connection portion 46 extending along the long side surface 40A1 of the holder 40 and are substantially an extension portion of the passage 48. The passages 48e and 48e extending in the direction are formed, and the passages 48e and 48e extend below the bearing structure portions 41 and 43 as shown in FIGS. Passages 48f and 48f extending so as to rise upward in the shaft hole outer wall portions 41b and 43b through which the shaft holes 41a and 43a do not pass are formed.

The rising passages 48f and 48f communicate with passages 48g and 48g in the cam shaft 50 supported by the shaft holes 41a and 43a through bearings. The passages 48g and 48g in the cam shaft 50 are 48h, It communicates with the cam portions 52 and 52 of the camshaft 50 through 48h (see FIGS. 11, 12, and 14).

The rising passages 48f and 48f further extend upward to reach the upper portions of the bearing structure portions 41 and 43, and from there to the short side portions 40B1 and 40B2 connecting the bearing structure portions 41, 42 and 43, 44. The passages 48i and 48i of the arcuate connecting portions 45 and 45 extending along the passage are formed, and oil is supplied to the camshafts 50 and 50 from the small openings 48j and 48j of the passages 48i and 48i.

The structure of the camshaft holder 40 is generally as described above, and the holder 40 is placed on the upper part of the cylinder head part 20 shown in FIG. 2 is mounted on the boss portion 25 shown in FIGS. 2 and 3 of the cylinder head portion 20 and is arranged and coupled by adopting the arrangement shown by the dotted line in FIG.

In this position, the two oil supply ports 48a and 48a of the oil supply passage shown in FIG. 8 and the long passage 48 in the groove shape are completely connected to the oil supply ports 24a and 24a in FIG. The lubricating oil that has been aligned and has passed through the passage in the cylinder head portion 20 communicates with the two aligned oil supply ports 24a, 24a and 48a, 48a, and the holder 40 through the mutual groove-shaped passages 24 and 48. Supplied in. Note that the openings of the oil supply ports 24 a and 48 a are also holes formed as holes for the stud bolts B when the camshaft holder 40 is coupled to the cylinder head portion 20.

As shown in FIGS. 11 and 12 and the like, a cam shaft 50 is fitted into and attached to the pair of shaft holes 41a, 42a and 43a, 44a of the holder 40 placed on the cylinder head portion 20, respectively. The cam shaft 50 to be mounted has the same structure as shown in FIG. 14, and all have the same structure. The cam shaft 50 has a predetermined length and a predetermined diameter shaft portion as shown in the figure. 51 and a cam portion 52 that is a portion projecting from the outer peripheral portion of the shaft portion 51 in a predetermined curve at a predetermined position of the shaft portion 51.

Further, the cam shaft 50 has the supply passage 48g described above for supplying oil to the cam portion 52 extending in the longitudinal direction at the central portion of the shaft, and the passage 48g is located at a position corresponding to the cam portion 52. The shaft 51 has a passage portion 48h that branches in the radial direction, and the branch passage portion 48h reaches the surface of the cam portion 52 and opens at the surface.

Shaft portions 53 and 54 having slightly narrow diameter portions are provided at both ends of the cam shaft 50, and inner race portions 55a and 56a of ball bearings 55 and 56 are fitted into the shaft portions 53 and 54, respectively. The outer race portions 55b and 56b of the ball bearing 55 are fitted into the pair of shaft holes 41a and 42a and 43a and 44a of the holder 40, respectively, and the pair of cam shafts 50 and 50 are rotatably supported by the holder 40. (See FIGS. 11 and 12).

Reference numeral 57 denotes a flange portion. A timing gear (not shown) is fixed to the flange portion 57, and the driving force of the timing chain interlocked with the crankshaft is transmitted to the camshafts 50 and 50 via the gear. The camshafts 50 and 50 are rotated at a predetermined rotational speed synchronized with the rotation of the crankshaft.

When the camshaft 50 is mounted on the holder 40, the cam portions 52 and 52 of the camshafts 50 and 50 come into contact with a roller 61 provided at a substantially central portion of the rocker arm 60 described later, and the roller 61 is moved. The rocker arm 60 is rocked by pressing the rocker arm 60 (see FIG. 1).

The rocker arm 60 has the structure shown in FIG. 15, that is, in the top view shown in FIG. 15B, the base 62 and the base 62 extend in parallel with each other and the tips thereof are mutually connected. It has a shape including a pair of connected arms 63, 63, and a shaft part 64 that crosses between the pair of arms 63, 63 is fixed to a substantially extending middle part of the arms 63, 63. A roller 61 that contacts the cam 52 of the cam shaft 50 described above is rotatably attached to the shaft portion 64.

Further, a screw hole 65 for attaching a pivot shaft 70, which will be described later, is provided in the base portion 62 of the rocker arm 60, and the rear connection portion 66 of the pair of arms 63, 63, as shown in FIG. A concave portion 67 is formed on the above-described intake / exhaust valve device 30, which has been subjected to appropriate surface processing to draw a predetermined curve with which the stem end 33 contacts with a slight gap. The contact with the gap between the stem end 33 and the concave portion 67 takes into consideration the adhesion between the valve head 31 of the valve device 30 and the valve face of the opening 22a of the intake / exhaust port 22 and the valve seat 22c during thermal expansion. It has been done.

The pivot shaft 70 attached to the screw hole 65 of the base portion 62 includes a structure portion that substantially forms a pivot bearing, which is a spherical portion 71, at the tip portion thereof as shown in FIG. 71, a concave hole 72 for good oil lubrication is formed in the center of the tip, and a shaft portion 74 having a threaded portion 73 of a predetermined length is extended through a neck portion constricted from the spherical portion 71, The extending end of the shaft portion 74 has a structure portion 75 that is square in order to serve as a spanner.

As is apparent from the reference of FIG. 1, the pivot shaft 70 is supported by a spherical portion 71 which is a tip portion of the pivot shaft 70 by the already described arcuate pivot receiving portion 47a formed in the cam shaft holder 40 so as to be pivotable. In addition, the extension shaft portion 74 provided with the screw portion 73 of the pivot shaft 70 is screwed into the screw hole 65 formed in the base portion 62 of the rocker arm 60 to constitute a so-called adjustment screw portion, and its position adjustment The pivot shaft 70 is attached to one side which is the base portion 62 of the rocker arm 60 by being tightened and fixed by the lock nut 76.

As can be understood from the above, eventually, as shown in FIG. 1, the rocker arm 60 at the time of mounting is one side of the rocker arm 60 via the spherical portion 71 of the pivot shaft 70 and the arc-shaped pivot receiver of the cam shaft holder 40. It is supported by the portion 47a so as to be pivotable, and the other side thereof is brought into contact with the stem end 33 of the intake / exhaust valve 30 through the curved concave portion 67 with a slight clearance, and the rotation of the substantially central portion thereof. The possible roller 61 is pressed against the cam 52 of the cam shaft 50 described above, and performs a swinging motion according to the rotation of the cam 52 synchronized with the rotation of the crankshaft (not shown).

The structure of each structural part in the embodiment of the present invention is as described above.
Here, the mounting relationship between these structural parts and the operation of the apparatus on which the mounting is performed will be briefly described.

The intake / exhaust valve device 30 is mounted on the cylinder head portion 20 (see FIG. 1). The valve device 30 is mounted by first inserting and fixing the valve guide 27 into which the stem portion 32 of the valve device 30 is inserted into the guide mounting hole 26 and then opening the intake and exhaust ports into the combustion chamber 21. The valve device 30 is mounted by inserting the stem end 33 of the valve device through the opening 22a of the valve 22 first. In addition, a spark plug (not shown) is inserted and fixed in the spark plug hole 23 (see FIGS. 2, 3, and 4) that opens in the center of the combustion chamber 21.

The camshaft holder 40 is connected to the shaft holes 41a and 42a and 43a and 44a of the bearing structure portions 41 and 42 and 43 and 44, which are paired with the holder 40, via bearings such as ball bearings 55 and 56, respectively. The shaft 50 is attached, and the camshaft 50 is attached from the large shaft holes 42a and 44a side of the shaft holes 41a, 42a and 43a, 44a of the bearing structure portions 41, 42 and 43, 44 forming the pair. The cam shaft 50 is inserted by using 42a1 and 43a1 (FIG. 9 ) (see FIGS. 11 and 12).

The mounting of the cam shaft 50 is performed by fitting and fixing the outer race portion 55b of the ball bearing 55 in one of the small shaft holes 41a and 43a in advance and inserting the cam shaft 50 through the large shaft holes 42a and 44a. The thin shaft portion 53 of the cam shaft 50 is fitted and fixed to the inner race portion 55a. Thereafter, the outer race portion 55b of the ball bearing 56 is fitted into the large shaft holes 42a and 44a while the cam shaft 50 is aligned with the large shaft holes 42a and 44a, and the inner race portion 55a is fitted to the cam shaft 50. The cam shaft 50 is attached to the cam shaft holder 40 by fitting (see FIGS. 11, 12, and 14).

Next, the rocker arm 60 is assembled to the camshaft holder 40. The rocker arm 60 is attached to the holder 40 by screwing the screw portion 73 of the pivot shaft 70 into the attachment screw hole 65 at one end of the rocker arm 60, and the spherical portion 71 at the tip of the pivot shaft 70 on the arc of the holder 40. A small assembly is made by fitting and supporting the pivot receiving portion 47a, and temporary assembly is performed (see FIGS. 1 and 16).

Thereafter, the intake / exhaust valve device 30 and the cylinder head portion 20 to which the spark plug is attached are coupled to the cylinder block 10, and the camshaft 50 and the rocker arm are connected to the cylinder head portion 20 as shown in FIG. A small camshaft holder 40 is attached.

The cam shaft holder 40 is fixed by the stud bolt B with the bottom surface portion 40C shown in FIG. 8 aligned with the top surface portion 20C of the cylinder head portion 20 shown in FIG. In the aligned state, the two oil supply ports 48a and 48a serving as the oil supply source to the camshaft holder 40 illustrated in FIG. 8 are the two oil supply ports 24a and 24a of the cylinder head portion 20 illustrated in FIG. And are in communication with each other.

After the camshaft holder 40 is attached to the cylinder head portion 20, the concave portion 67 at the other end of the rocker arm 60 assembled to the holder 40 is brought into contact with the stem end 33 of the valve device 30, and the rocker arm is attached to the camshaft 50. A rotating roller 61 provided substantially at the center of 60 abuts (see FIG. 1).

Then, the adjustment in the mounting of the rocker arm 60 is performed by adjusting the screwing amount of the screw portion 73 of the pivot shaft 70 constituting the adjusting screw, and the adjustment is performed when the roller 61 of the rocker arm 60 is not in contact with the cam 52. , The valve stem end 33 and the rocker arm 60 are adjusted so that there is an appropriate gap, that is, the valve clearance, between the contact portion of the concave portion 67 at the other end. Is fixed.

Of course, the assembly of the rocker arm 60 to the holder 40 may be performed after the holder 40 is attached to the cylinder head portion 20.

The outline of the mounting of each structural part is as described above. In the mounted state, the cam shaft 50 is rotated via a cam chain and timing gear (not shown) in conjunction with the rotation of the crank shaft (not shown). The rotation of the cam 52 due to the rotation of the cam shaft 50 presses the roller 61 of the rocker arm 60 that contacts the cam surface 52 a of the cam 52, and the rocker arm 60 is moved through the roller 61 to the spherical portion 71 of the pivot shaft 70. Oscillate around the fulcrum.

The rocking motion of the rocker arm 60 about the spherical portion 71 of the pivot shaft 70 pushes down the stem end 33 of the intake / exhaust valve device 30 against the valve spring S, and pushes up the stem 32. The stem 32 of the valve device 30 moves up and down by the action of the valve spring S, and the valve head 31 at the lower end of the stem 32 opens and closes the opening 22a of the intake / exhaust port 22 in the combustion chamber 21 described above. . As is well known, the intake action to the combustion chamber 21 and the exhaust action of the exhaust gas from the combustion chamber 21 are performed.

  Since the embodiment shown in FIGS. 1 to 16 of the present invention has the above configuration, the rocker arm pivot receiving portion 47a of the rocker arm 60 is integrally formed with the cam shaft holder 40. The holder 40 can be assembled in a small size, and set flow and management become unnecessary, so that the assembling property is improved.

The shaft holes 41a, 42a and 43a, 44a of the bearing structure portions 41, 42 and 43, 44 of the camshaft holder 40 have a continuous perfect circle structure, and all the bearing structure portions are integrally formed, and the cylinder head portion. Since the mounting seat surface to 20 is extended and an oil passage is formed here, there is no need to form a complicated oil passage in the cylinder head portion 20, and the structure of the oil passage is simplified. Since the passage processing becomes easy, the processing time can be shortened.

It is a general view which shows the valve mechanism part of this invention, and the main structure part of the periphery of it. It is a figure which shows the structure of the cylinder head part of this invention, and is a top view in FIG. It is a figure which shows the structure of the cylinder head part of this invention, and is AA sectional drawing of FIG. It is a figure which shows the structure of the cylinder head part of this invention, and is a bottom view in FIG. It is a figure which shows the structure of the cylinder head part of this invention, and is a figure which shows the BB cross section of FIG. 4, It is the figure by which the assembly | attachment of the cam shaft holder etc. was shown with the broken line. It is a figure which shows the structure of the cam shaft holder of this invention, and is a top view in FIG. It is a figure which shows the structure of the cam shaft holder of this invention, and is a figure which shows CC cross section of FIG. It is a figure which shows the structure of the cam shaft holder of this invention, and is a bottom view in FIG. It is a figure which shows the structure of the cam shaft holder of this invention, and is a figure which shows the DD cross section of FIG. It is a figure which shows the structure of the cam shaft holder of this invention, and is a figure which shows Z direction view in FIG. It is a figure which shows the structure of the cam shaft holder of this invention, and is a figure which shows the EE cross section of FIG. It is a figure which shows the structure of the cam shaft holder of this invention, and is a figure which shows the FF cross section of FIG. It is a figure which shows the structure of the cam shaft holder of this invention, and is a figure which shows the GG cross section of FIG. It is a figure which shows the structure of the cam shaft of this invention, (a) is a longitudinal cross-sectional view of a shaft, (b) is an end view of a shaft. It is a figure which shows the structure of the rocker arm of this invention, (a) is the sectional side view, (b) is the top view, (c) is the end view, Furthermore (d ) Is a cross-sectional view of HH in (a). It is a figure which shows the structure of the pivot axis | shaft of this invention, (a) is the side view, (b) is the end view. It is a figure which shows the conventional valve operating mechanism part and the main structure part of the periphery.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Cylinder block, 10a ... Cylinder hole, 20 ... Cylinder head part, 20A1, A2 ... Long side surface, 20B1, B2 ... Short side surface, 20C ... Upper surface part, 21 ... -Combustion chamber, 22 ... Suction / exhaust port, 22a ... Suction / exhaust port opening, 22b ..., 22c ..., 23 ... Spark plug mounting hole, 23a ... Spark plug mounting Hole opening, 24 ... oil passage, 24a ... oil supply port, 25 ... boss, 26 ... valve guide mounting hole, 26a ... opening, 27 ... valve guide, 28. ..Through hole 29 ... Spring receiver, 30 ... Suction / exhaust valve device, 31 ... Valve head, 32 ... Valve stem, 33 ... Stem end, 34 ... Spring receiver, 40 ... camshaft holder, 40A1, A2 ... long side, 0B1, B2 ... short side, 40C ... bottom surface, 41,42,43,44 ... bearing structure, 41a, 42a, 43a, 44a ... shaft hole, 42a1,44a1 ... expanded Diameter hole part, 45, 46 ... Connection part, 46a ... Base part, 47 ... Connection structure part, 47a ... Pivot receiving part, 48 ... Oil passage, 48a ... Oil supply port, 48b, 48c, 48d, 48e, 48f, 48g, 48h, 48i, 48j ... oil passage, 49 ... space portion, 50 ... cam shaft, 51 ... shaft portion, 52 ... cam portion 52a ... cam surface, 53, 54 ... thin shaft part, 55, 56 ... ball bearing, 55a, 56a ... inner race, 55b, 56b ... outer race, 57 ... flange part , 60 ... Rocker arm, 61 ... Roller, 62 ... Base, 63 ... Arm , 64 ... shaft part, 65 ... screw hole, 66 ... arm rear part connection part, 67 ... concave part, 70 ... pivot shaft, 71 ... spherical part, 72 ... concave Hole 73 ... Screw part 74 ... Shaft part 75 ... Square structure part 76 ... Lock nut B ... Stud bolt E ... Internal combustion engine F ... Cooling fins, HC ... head cover, CR ... connecting rod, P ... piston, S ... spring.

Claims (2)

In an internal combustion engine comprising a cylinder head portion, a camshaft, and a rocker arm that is driven by the camshaft to open and close an intake / exhaust valve device,
A cam shaft holder provided separately from the cylinder head portion, and the cam shaft holder has a substantially rectangular outer shape when viewed in the axial direction of the cylinder head portion; Four bearing structure portions having circular shaft holes are provided, and the four bearing structure portions are integrally coupled by a connection portion extending along the substantially rectangular side surface, and the bearing structure portions facing each other in pairs are provided. The camshafts are rotatably supported, and the bearing structure portions facing each other in pairs are coupled by two connection structure portions traversing the camshaft holder, and the rocker arms are respectively connected to the connection structure portions. is the formed on the rocker arm pivot receiving portion is integrally pre-Symbol the mounting seat surface to the cylinder head portion of the cam shaft holder, a cam shaft holder refueling connected to the filler opening of the oil supply passage in said cylinder head unit Mouth formation An internal combustion engine characterized in that the camshaft holder side oil supply port communicates with an oil passage in the camshaft holder. The camshaft holder side oil supply port of the mounting seat surface to the cylinder head part of the said camshaft holder is formed in one of the connection parts extended along the said substantially rectangular side surface. The internal combustion engine described.

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