JPH10148113A - Sohc type internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the structure of an oil passage and miniaturize a rocker shaft in a SOHC type internal combustion engine in which a single rocker shaft is fixedly arranged upward a camshaft, and hydraulic valve operation characteristic changing means is arranged on a plurality of rocker-arms composing one of a suction or exhaust side valve system mechanism. SOLUTION: A single first oil supply passage 64 ranging the lubrication parts of both valve system mechanisms 30I, 30E and hydraulic valve operation changing means, is arranged in a rocker shaft 25, the rocker shaft 25 is fastened to upper surfaces of cam holders 23 by bolts 29 which cross the first oil supply passage 64 and screwed in the cam holders 23, second oil supply passages 104 through which lubricating oil is introduced between the cam holders 23 and cam journal parts 24a, are arranged in the bolts 29 by being opened into the first oil supply passage 64, and at least a part of cross sectional areas of the second oil supply passages 104 is set to be smaller than the cross sectional area of the first oil supply passage 64.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an SOHC type internal combustion engine having a single camshaft and a single rocker shaft, and more particularly to an SOHC type internal combustion engine in which a plurality of rocker arms are provided with hydraulic valve operating characteristic changing means. About.

[0002]

2. Description of the Related Art Conventionally, such an SOHC type internal combustion engine has been already known, for example, from Japanese Patent Application Laid-Open No. 17707/1992. In this type of engine, an oil passage communicating with a hydraulic valve operating characteristic changing means is provided in a rocker shaft. And an oil passage for valve system lubrication are provided in the rocker shaft in parallel with each other.

[0003]

However, in the configuration in which two oil passages are provided in the rocker shaft as in the above-described conventional case, not only is the oil passage configuration complicated, but also the required flow in both oil passages is increased. The outer diameter of the rocker shaft increases in order to secure a road area, which may lead to an increase in the size of the valve train.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an SOHC type internal combustion engine capable of simplifying an oil passage configuration and downsizing a rocker shaft.

[0005]

According to a first aspect of the present invention, there is provided a cam holder comprising a plurality of cam journals provided on a single camshaft, the plurality of cam journals being provided integrally with a cylinder head. Each is rotatably supported by a single rocker shaft common to the intake-side valve operating mechanism provided between the camshaft and the intake valve and the exhaust-side valve operating mechanism provided between the camshaft and the exhaust valve.
Fixed to the cylinder head above the camshaft,
In a SOHC type internal combustion engine in which one of the intake-side and exhaust-side valve trains constitutes one of a plurality of rocker arms supported by the rocker shaft and a hydraulic valve operating characteristic changing means is provided, each cam holder includes A bearing hole for inserting and supporting the journal portion is formed, and a single unit extending along the axial direction of the rocker shaft connected to the lubricating portion of the intake side and exhaust side valve trains and the hydraulic valve operating characteristic changing means. A first oil supply passage is provided in the rocker shaft, and the rocker shaft is fastened to an upper surface of each cam holder by a bolt that is screwed into each of the cam holders across the first oil supply passage, and an inner surface of each of the bearing holes and each of the cam journals. A second oil supply passage for guiding oil between the outer surfaces of the
One end thereof is connected to the first oil supply passage and provided on each bolt, and a cross-sectional area of at least a part of the second oil supply passage is set to be smaller than a cross-sectional area of the first oil supply passage.

According to the first aspect of the present invention, only the first oil supply passage which can supply oil to the lubricating portions of the intake-side and exhaust-side valve operating mechanisms and the hydraulic valve operating characteristic changing means is provided.
Each of the bolts is provided in the rocker shaft with a second oil supply passage for guiding oil to a lubricating portion of the camshaft, so that the oil passage configuration in the rocker shaft can be simplified. Enlargement of the shaft can also be avoided. Moreover, since the second oil supply path is provided in the bolt for fastening the rocker shaft to the cam holder,
Compared with the case where the second oil supply passage is provided in the cam holder, the width of the cam holder along the axial direction of the camshaft can be reduced to contribute to downsizing of the cylinder head.
Further, since the cross-sectional area of at least a part of the second oil supply path is smaller than the cross-sectional area of the first oil supply path, the hydraulic pressure required by the hydraulic valve operating characteristic changing means is secured in the first oil supply path while the second oil supply path is maintained. Can supply oil to the lubricating portion of the camshaft.

According to a second aspect of the present invention, in addition to the configuration of the first aspect of the present invention, the second oil supply passage allows an outer end to communicate with the first oil supply passage so that the bolt is connected to the first oil supply passage. A radial oil passage extending along the radial direction of the bolt, and an axial oil passage formed such that the upper end communicates with the inner end of the radial oil passage and is formed longer than the radial oil passage along the axial direction of the bolt. By forming a throttle in the radial oil passage, the length of the drill at the time of drilling for forming the throttle is relatively shorter than when a throttle is formed in the axial oil passage. And the perforation process is facilitated.

According to a third aspect of the present invention, in addition to the configuration of the first or second aspect of the present invention, a larger diameter than the second oil supply passage is provided between a lower end of the bolt and an outer surface of the cam journal portion. By forming the oil reservoir, the oil from the oil reservoir can be constantly supplied between the cam journal portion and the cam holder.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.

FIGS. 1 to 7 show one embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a main part of an internal combustion engine, FIG. 2 is a plan view of FIG. FIG. 4 is an enlarged sectional view taken along line 4-4 of FIG. 1, FIG. 5 is an oil supply system diagram, and FIG. 6 is a control valve means and a first valve. FIG. 7 is a sectional view taken along the line 7-7 in FIG. 6, showing a cutaway side view showing an oil passage configuration between the oil supply passages.

Referring first to FIGS. 1 and 2, a cylinder head 11 of a multi-cylinder, for example, four-cylinder, SOHC type internal combustion engine has a pair of intake valve ports 13 opening on a ceiling surface of a combustion chamber 12 for each cylinder. A pair of exhaust valve ports 14 are provided, and both intake valve ports 13 and both exhaust valve ports 1 are provided.
The intake valves 15 and the exhaust valves 1 can open and close the respective 4.
Guide cylinders 17 for guiding 6... Movably in the axial direction
Is press-fitted. At the upper end of each intake valve 15 and each exhaust valve 16 projecting from the guide cylinders 17, 18, retainers 19, 20 are fixed, and the cylinder head 11 and each retainer 19, 20 are fixed. Are provided between the coil springs 21 and 22. The spring force of the valve springs 21 and 22 is increased upward, that is, toward the valve closing direction. Is given to

A plurality of cylinder heads 11 (e.g., five cylinders) are provided at intervals in the axial direction of a crankshaft (not shown).
Are provided integrally, and a camshaft 24 having an axis parallel to the crankshaft.
Are rotatably supported by the cam holders 23 above the combustion chamber 12. That is, each of the cam holders 23 is provided with a bearing hole 23a for allowing the cam journal portion 24a provided on the cam shaft 24 to be inserted therethrough and rotatably supported.

Referring also to FIG.
And the intake-side valve operating mechanism is the pair of intake valves 15 ... between 30 _I
Single but also is intended to camshaft 24 and a pair of exhaust valves 16 ... while respectively provided an exhaust-side valve operating mechanism 30 _E, which is common to the intake side and exhaust-side valve operating mechanism 30 _I, 30 _E Rocker shaft 25 is camshaft 2
4 is fixedly arranged so as to have an axis parallel to the camshaft 24. That is, each cam holder 23 ...
A flat support surface 26 is provided at the upper end of the rocker shaft 25. A flat engagement surface 27 is provided on an upper surface of a portion corresponding to each cam holder 23 of the rocker shaft 25, and a flat engagement surface 27 is provided on a lower surface. Flat mounting surfaces 28 are provided, respectively.
Bolts 29 penetrating up and down through rocker shaft 25 with mounting surfaces 28 joined to supporting surfaces 26 respectively
Are screwed into the respective cam holders 23 until the locking heads 29a at the upper ends thereof are engaged with the engagement surfaces 27.

Moreover, on a projection onto a plane orthogonal to the axis of the camshaft 24 and the rocker shaft 25, the two intake valves 15 are substantially symmetrical with respect to a straight line connecting the centers of the camshaft 24 and the rocker shaft 25. and the intake side and the valve operating mechanism 30 _I, and both the exhaust valves 16 ... and the exhaust-side valve-operating mechanism 30 _E is disposed.

The intake-side valve operating mechanism 30 _I includes first and second intake-side rocker arms 31 and 32 which are arranged adjacent to each other and are commonly swingably supported by the rocker shaft 25. mechanism 30 _E is provided with a pair of exhaust-side rocker arms 33, 33 swingably supported by the rocker shaft 25 is disposed so as to sandwich both the intake side rocker arms 31 and 32 from both sides. On the other hand, camshaft 2
4 includes a first intake side cam 34 corresponding to the first intake side rocker arm 31, a second intake side cam 35 corresponding to the second intake side rocker arm 32, and both exhaust side rocker arms 33,
Exhaust-side cams 36, 36 respectively corresponding to the first and second intake-side rocker arms 33, 33 are rotatably supported on the first intake-side rocker arm 31 so as to be in contact with the first intake-side cam 34. The rocker arm 32 is integrally provided with a cam slipper 38 which is in direct contact with the second intake side cam 35, and the exhaust side rocker arms 33, 33 have the exhaust side cam 3.
Rollers 39, 39 that come into rolling contact with the rollers 6, 36 are rotatably supported.

The first and second intake side rocker arms 3
The connecting arms 41 and 42 are integrally provided with the connecting arms 41 and 42, respectively, and extend to the upper position side of the intake valves 15. Tappet screws 43 contact the upper ends of the intake valves 15, respectively.
Will open and close in response to the rocking movement of the corresponding rocker arms 31 and 32. Further, connecting arms 44, 44 extending above the exhaust valves 16 are provided integrally with the exhaust-side rocker arms 33, 33, respectively. Tappet screws 45, 45, each screwed as possible,
Each exhaust valve 16 contacts the upper end of each exhaust valve 16.
Are opened and closed in response to the rocking movements of the corresponding rocker arms 33, 33.

In the low-speed operation range of the engine, the first intake side rocker arm 31 swings by the first intake side cam 34, and the first intake side rocker arm 31 causes one of the intake valves 15 to open and close. The second intake-side rocker arm 32 swings by the second intake-side cam 35, and the other intake valve 15 is opened and closed by the second intake-side rocker arm 32.
The operation amount of the intake side rocker arm 31 is set to be larger than the operation amount of the second intake side rocker arm 32. Therefore, the opening / closing lift amount of one intake valve 15 is larger than the opening / closing lift amount of the other intake valve 15. large. The second
Even if the intake-side cam 35 stops or substantially stops the second intake-side rocker arm 32 in the low-speed operation range of the engine, the other intake valve 15 closes or substantially closes. Good.

In FIG. 4, first and second intake rocker arms 31 and 32 arranged adjacent to each other are provided with the first and second intake cams in the low speed operation range of the engine. The first and second intake rocker arms 31 and 32 are interlocked and operated by the first intake cam 34 in the high-speed operation range of the engine. 15 ...
A hydraulic valve operating characteristic changing means 46 for changing the valve operating characteristics of the engine according to the operating state of the engine is provided.

The hydraulic valve operating characteristic changing means 46 moves between a position where the first and second intake side rocker arms 31 and 32 are connected and a position where the connection is released along an axis parallel to the axis of the rocker shaft 25. Possible Synchro Pin 4
7, a timing piston 48 for pressing the synchro pin 47 to the connection position side by the action of hydraulic pressure, a regulating member 49 connected to the synchro pin 47 on the opposite side to the timing piston 48, and the regulating member 49 and the second A return spring 50 provided between the intake side rocker arms 32;

The first intake side rocker arm 31 is provided with a bottomed fitting hole 51 opened to the second intake side rocker arm 32 side so as to extend in parallel with the rocker shaft 25, and has one end closed. A timing piston 48 formed in a bottom cylindrical shape is slidably fitted in the fitting hole 51, and a hydraulic chamber 52 is formed between one end of the timing piston 48 and a closed end of the fitting hole 51. You. The sync pin 47 is slidably fitted in the fitting hole 51 with one end coaxially contacting the other end of the timing piston 48.

The other end of the synchro pin 47 can be fitted to the second intake side rocker arm 32 so that the first
A bottomed fitting hole 53 opened to the intake side rocker arm 31 side.
Is provided so as to extend in parallel with the rocker shaft 25, and an open hole 54 is provided coaxially at the closed end of the fitting hole 53. Thus, the regulating member 49 is formed in a cap shape having an open side opposite to the synchro pin 47, and one end of the regulating member 49 is coaxially connected to the other end of the synchro pin 47. Moreover, the flange portion 4 which protrudes radially outward is provided on the opening end side, that is, the other end side of the regulating member 49.
9 a is provided, and the regulating member 49 is slidably fitted in the fitting hole 54 so as to guide the flange 49 a on the inner surface of the fitting hole 54.

The return spring 50 is provided between the closed end of the fitting hole 54 and the regulating member 49.
Exerts a spring force for pressing the regulating member 49, the synchro pin 47 and the timing piston 48 toward the hydraulic chamber 52 side. In order to prevent the regulating member 49 from dropping out of the fitting hole 54, a retaining ring 55 that can be engaged with the flange 49a of the regulating member 49 is mounted on the inner surface of the fitting hole 54.

Such a hydraulic valve operating characteristic changing means 46
According to the above, when the hydraulic pressure in the hydraulic chamber 52 is low, the contact end face of the synchro pin 47 and the regulating member 49 is brought to a position corresponding to between the first and second intake side rocker arms 31 and 32 by the spring force of the return spring 50. The both intake side rocker arms 31 and 32 are provided with a synchro pin 47 and a regulating member 4.
9 can swing independently while sliding on each other, but when the hydraulic pressure in the hydraulic chamber 52 becomes high, the synchro pin 47 is pushed by the timing piston 48, so that the other end of the synchro pin 47 Is pressed into the fitting hole 54 of the second intake side rocker arm 32 while pressing the regulating member 49, and the two intake side rocker arms 31, 32 are connected via the synchro pin 47. They will work together as a unit.

The two intake valves 15... Alternately repeat opening and closing operations and closing of the valve according to the rotation of the camshaft 24. Rocker arm 3 on both intake sides
If the connecting and disconnecting operations of the first and second lockers 1 and 32 are not started, the two rocker arms 31 and 32 by the synchro pin 47 are used.
Connection and disconnection may not be smooth. Therefore, regardless of the switching timing of the hydraulic pressure of the hydraulic chamber 52, the first intake side is set in order to set the connection start timing and the connection release start timing of the both intake side rocker arms 31 and 32 by the synchro pin 47 at the beginning of the valve closing stationary timing. The rocker arm 31 is provided with a trigger mechanism 56.

The trigger mechanism 56 includes a timing plate 57 that can rotate around a pin 61 parallel to the rocker shaft 25 in accordance with the swinging motion of the first intake side rocker arm 31. A slit 58 for guiding the timing plate 57 is provided on the base 31 so that the tip of the timing rig plate 57 can protrude inward from the inner surface of the fitting hole 51. On the other hand, the timing piston 48
A synchro pin 47 and a regulating member 49
Contact end faces of the first and second intake side rocker arms 31,
32, the timing plate 57
An annular engaging step portion 59 is provided for engaging the leading end portion of the lock plate, and a position corresponding to the timing plate 57 when the synchro pin 47 moves to a position connecting the first and second intake side rocker arms 31 and 32. With timing piston 48
An annular engagement groove 60 is provided on the outer periphery of the lock member so that the distal end of the timing plate 57 can be engaged.

In such a trigger mechanism 56, when the first intake side rocker arm 31 is oscillating, the timing plate 57 is engaged with the engaging step 59 or the engaging groove 6 at the distal end thereof.
It operates in the direction to release the engagement with zero. Therefore, in a state where both the intake side rocker arms 31 and 32 are disconnected, the first
Even when hydraulic pressure acts on the hydraulic chamber 52 when the intake side rocker arm 31 is at rest, the timing piston 48 is
The operation of the timing piston 48 can be performed when the first intake side rocker arm 31 swings, without immediately starting the operation in the direction of increasing the volume of the second. However, since the two intake side rocker arms 31 and 32 relatively swing, the synchro pin 47 does not fit into the fitting hole 54 of the second intake side rocker arm 32, and the two intake side rocker arms 31 and 32 swing. When the stationary state is reached after the movement, the timing piston 48 starts to move in accordance with the axes of the fitting holes 51, 54, and the other end of the synchro pin 47 fits into the fitting hole 54. When the two intake side rocker arms 31 and 32 are connected to each other, the first intake side rocker arm 31 is connected.
When the hydraulic pressure is applied to the hydraulic chamber 52 when the hydraulic cylinder 52 is at rest, the timing piston 48 immediately starts operating in the direction of reducing the volume of the hydraulic chamber 52 by the engagement of the timing plate 57 with the engagement groove 60. Therefore, the timing piston 48 can be operated when the first intake side rocker arm 31 swings. However, the second intake side rocker arm 32
Is swinging following the first intake side rocker arm 31, a shearing force is acting on the synchro pin 47, and the synchro pin 47 does not move to the first intake side rocker arm 31 side, Rocker arms 31, 3 on both intake sides
In response to the release of the action of the shearing force when the stationary state is reached after the swinging motion of 2, the synchro pin 47 pushes the timing piston 48 by the spring force of the return spring 50 toward the fitting hole 51 side. Return, both intake side rocker arms 3
The connection between 1 and 32 is released.

The rocker shaft 25 is provided with a first oil supply passage 64 extending along the axial direction of the rocker shaft 25 and having both ends closed, for example, coaxially over substantially the entire length of the rocker shaft 25. At the portion corresponding to the first intake side rocker arms 31, an oil passage 65 communicating with the first oil supply passage 64 is provided on the side wall of the rocker shaft 25, and the first intake side rocker arms 31 are provided with the first intake side. An oil passage 66 for connecting the oil passage 65 to the hydraulic chamber 52 regardless of the rocking state of the rocker arms 31.
... are provided.

In FIG. 5, oil in an oil pan 67 is pumped up by an oil pump 69 via a strainer 68, and supplied from the oil pump 69 to a main gallery 71- via a filter 70. Oil pump 69
A relief valve 72 is provided between the discharge side and the oil pan 67.

The main gallery 71 extends in the axial direction of the crankshaft, and a plurality of branch oil passages 74 from the main gallery 71 to supply oil to the crank journal portions 73 of the crankshaft.
Is branched.

An oil passage 75 communicates with one end of the main gallery 71. The oil passage 75 is connected to a control valve means 81 via an oil passage 76, and the control valve means 81 raises and lowers the hydraulic pressure. The oil whose switching is controlled is supplied to the first oil supply passage 64 via the oil passage 77. Further, the other end of the main gallery 71 communicates with one end of an oil passage 78, and the other end of the oil passage 78 communicates with an oil sump 79 formed on the cylinder head 11. Is supplied to a tensioner 80 for applying tension to a timing chain (not shown) for transmitting the rotational power of the crankshaft to the camshaft 24.

6 and 7, the camshaft 2
A distributor 82 connected to the cam journal portion 24a at one end of the cylinder head 11 is attached to the cylinder head 11 at one end of the cam shaft 24, and a control valve means is provided on a side wall of the cylinder head 11 at a position corresponding to the distributor 82. 81 is attached.

The control valve means 81 includes a spool valve 83 and an electromagnetic valve 84. A housing 85 of the spool valve 83 is mounted on the cylinder head 11, and the electromagnetic valve 84 is mounted on the housing 85.

The spool valve 83 includes a housing 8 having an input port 86, an output port 87, and a release port 88.
5 and an upward movement position (position shown in FIG. 6) in which the output port 87 communicates with the release port 88 but is cut off from the input port 86, and the output port 87 is communicated with the input port 86 but is cut off from the release port 88. A spool 89 slidably fitted to the housing 85 so as to be movable between the lower movement positions, and a plug 9 fixed to the housing 85 by forming a pilot chamber 91 between the spool 89 and the upper end of the spool 89.
0 and a spring 92 provided between the spool 89 and the housing 85 by exerting a spring force for pressing the spool 89 to the side where the volume of the pilot chamber 91 is reduced.

On the other hand, the main gallery 71 shown in FIG.
Is formed annularly between one of the plurality of through bolts 100 for fastening the cylinder head 11 and the cylinder block and the cylinder head 11 and the cylinder block. An oil passage 76 communicating with the upper end is opened in the side wall of the cylinder head 11 at a position corresponding to the input port 86 of the housing 85 in the spool valve 83. Moreover, the housing 85 is attached to the cylinder head 11 with the filter 93 interposed between the oil passage 76 and the input port 86 interposed between the oil passage 76 and the input port 86.
The oil from 76 is supplied to input port 8 via filter 93.
6 will be introduced. The housing 85 is provided with a leak jet 94 connecting the input port 86 and the output port 87. Even when the input port 86 and the output port 87 are shut off by the spool 89, the input port 86 shuts off the leak jet 94. Through the output port 87.

The housing 85 allows the output port 87 to pass through an oil passage 77 provided in the cylinder head 11 and the release port 88 to correspond to an opening 95 provided in the cylinder head 11.
The housing 85 is provided with a pressure sensor 96 for detecting the oil pressure of the output port 87.

The solenoid valve 84 switches the communication between the input port 86 and the pilot chamber 91 and shuts off. When the solenoid valve 84 connects the input port 86 and the pilot chamber 91 to each other, the pilot chamber 91 is raised. In response to the hydraulic pressure, the spool 89 moves to a lower position where the output port 87 communicates with the input port 86 but is cut off from the release port 88, and the solenoid valve 83 moves between the input port 86 and the pilot chamber 91. Is shut off, the spool 89 becomes low in response to the low hydraulic pressure in the pilot chamber 91.
Is moved by the spring force of the spring 92 to the upper position where the output port 87 communicates with the release port 88 but is cut off from the input port 86.

The oil passage 77 is provided in the cylinder head 11 so as to extend obliquely upward from the output port 87 to one end of the rocker shaft 25.
Is connected to a first oil supply passage 64 via a cylindrical pin 97 provided between an upper end of the cam holder 23 corresponding to one end of the rocker shaft 25 and one end of the rocker shaft 25.

The first oil supply passage 64 formed in the rocker shaft 25, together with the refueling by switching the hydraulic pressure of high and low in the hydraulic valve operating characteristic changing means 46 ..., intake-side and exhaust-side valve operating mechanism 30 _I , 30 lubrication of _E, that is, those that also performs the function of the fuel supply to the rocker arms 31, 32, 33 ... lubrication of, the rocker shaft 25 at a position corresponding to the second intake-side rocker arms 32 ..., rocker shaft An oil hole 98 for supplying oil from the first oil supply passage 64 is provided between the second intake rocker arm 25 and the second intake side rocker arm 32.
At the position corresponding to the exhaust side rocker arms 33, 33, oil holes 99, 99... For supplying oil from the first oil supply passage 64 are provided between the rocker shaft 25 and the exhaust side rocker arms 33, 33. The rocker shaft 25 is connected to the first oil supply passage 64 so that the oil passages 66 provided in the first intake side rocker arms 31 communicate with the hydraulic chamber 52 of the hydraulic valve operating characteristic changing means 46. Are provided between the first intake side rocker arms 31 and the rocker shaft 25 from the oil passages 65.

Further, the oil in the first oil supply passage 64 is supplied between the cam journals 24a of the cam shaft 24 and the cam holders 23 through the plurality of second oil supply passages 104.

The second oil supply passages 104 are provided on the rocker shaft 2.
4 are formed in a plurality of bolts 29 for fastening the upper surface of each cam holder 23.
3 are guide holes 101 having a lower end opened in the inner surface of the bearing hole 23a, and are coaxially connected to the upper end of the guide hole 101 with a diameter larger than that of the guide hole 101.
Are provided on the upper surface, i.e., the support surfaces 26, of which the upper ends are opened. The bolts 29 are screwed into the screw holes 102 so as to cross the first oil supply passage 64 of the rocker shaft 25.

The second oil supply passages 104 are formed such that at least a part of the cross-sectional area thereof is smaller than the cross-sectional area of the first oil supply passage 64.
The outer end of the bolt 29 is opened to the outer surface of the bolt 29 so as to communicate with the bolt 4, and the radial oil passage 105 extends in the radial direction of the bolt 29, and the upper end is connected to the inner end of the radial oil passage 105. An axial oil passage 107 which is formed longer than the radial oil passage 105 along the axial direction and has a lower end coaxially communicating with the guide hole 101, and a throttle 106 is provided at an inner end of the radial oil passage 105. It is formed.

Further, the outer diameter of the bolt 29 is set such that a gap is formed between the inner surface of the first oil passage 64 and the bolt 29 at a portion crossing the first oil passage 64.
By doing so, the radial oil passage 1 in the second oil supply passage 104 can be positioned without positioning the bolt 29 in the circumferential direction.
05 can be reliably connected to the first oil supply passage 64.

Each of the cam holders 23 has a guide hole 101 for opening a lower end on the inner surface of the bearing hole 23a,
Since the screw holes 102 having a diameter larger than 1 are provided coaxially, the lower end of the bolts 29 and the cam journal portions 24a are provided between the lower end of the bolts 29 and the cam journal portions 24a than the axial oil passage 107 in the second oil supply passage 104. An oil reservoir 109 having a large diameter is formed.

The maximum tightening position of the bolts 29 is determined at the lower end of the screw holes 102.
Are set so that a slight predetermined distance is generated between the lower ends of the bolts 29 and the lower ends of the screw holes 29 in a state in which the locking heads 29a of the. By doing so, over-tightening of the bolts 29 can be prevented.

Further, through bolts 100 arranged on both sides of each cam holder 23, and the cam holders 23, respectively.
A pair of ribs 108, 108... Protruding upward in a direction perpendicular to the axis of the rocker shaft 25 is provided on the cylinder head 11 between the fastening portion of the rocker shaft 25 and the rib 108. , 108 ...
Supporting rigidity of rocker shaft 25 and camshaft 24
Has been greatly increased in support stiffness.

Next, the operation of this embodiment will be described. In the rocker shaft 25, each rocker arm 31,
The first oil supply passage 64 for supplying oil to the lubricating portions 32, 33, 33, and the hydraulic valve operating characteristic changing means 46 is only provided so as to extend in the axial direction of the rocker shaft 25. A plurality of cam holders 2
3 to the bolts 29 for fastening to the camshaft 2
Since the second oil supply passages 104 for guiding the oil to the lubricating portions between the camshafts 4 and the cam holders 23 are provided, the rocker shafts are provided in comparison with the conventional case where a pair of oil supply passages are provided in parallel in the rocker shaft 25. The configuration of the oil passage in the shaft 25 can be simplified, and the rocker shaft 25
Therefore, the size of the valve train can be reduced. Moreover, the width of the cam holders 23 along the axial direction of the camshaft 24 can be reduced as compared with the case where the second oil supply passages are provided in the cam holders 23, so that the cylinder head 11 can be downsized. it can.

Since the cross-sectional area of at least a part of the second oil supply passages 104 is set smaller than the cross-sectional area of the first oil supply passage 64, the hydraulic valve operating characteristic changing means 4 is provided.
6 can guide the oil to the lubricating portion between the camshaft 24 and the cam holders 23 while securing the required oil pressure in the first oil supply passage 64.

Further, in the second oil supply passages 104,...
The drill length for drilling is relatively short,
When a throttle is formed in the axial oil passage 107 along the axial direction of the bolt 29, the drill becomes relatively long,
The accuracy of the drilling process is inferior, and the hole diameter is 3 or 4
Since it is necessary to sequentially change the processing so as to form a step, the processing becomes complicated.

Further, an oil reservoir 109 having a diameter larger than that of the second oil supply passage 104 is formed between the lower ends of the bolts 29 and the cam journals 24a. Can be constantly supplied between the cam journals 24a and the cam holders 23.

Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the appended claims. It is possible to do.

For example, in the above-described embodiment, two exhaust-side rocker arms 33, 33 per cylinder are provided with the rocker shaft 25.
However, the present invention can be applied to a case where there is only one exhaust side rocker arm, and the present invention is applied to a valve train in which the exhaust side rocker arm is provided with a hydraulic valve operating characteristic changing means. Can be applied, and the entire length of the radial oil passage 105 can be formed as a throttle.

[0052]

As described above, according to the first aspect of the present invention, only the first oil supply passage is provided in the rocker shaft,
The second oil supply passage for guiding oil to the lubricating portion of the camshaft is provided in each bolt, thereby simplifying the oil passage configuration in the rocker shaft, reducing the size of the rocker shaft and reducing the width of the cam holder. Thus, the size of the cylinder head can be reduced. In addition, since the cross-sectional area of at least a part of the second oil supply passage is smaller than the cross-sectional area of the first oil supply passage, the camshaft and the cam holder while securing the required oil pressure in the first oil supply passage by the hydraulic valve operating characteristic changing means. It is possible to guide the oil to the lubricating portion between them.

According to the second aspect of the present invention, since the throttle is formed in the radial oil passage of the second oil supply passage, the length of the drill at the time of drilling for forming the throttle is relatively short. In addition, the boring process can be facilitated.

Further, according to the third aspect of the present invention, an oil reservoir having a diameter larger than that of the second oil supply passage is formed between the lower end of the bolt and the outer surface of the cam journal. Oil from the oil reservoir can be supplied at all times.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of an internal combustion engine.

FIG. 2 is a plan view as viewed in the direction of arrow 2 in FIG.

FIG. 3 is a sectional view taken along the axial direction of the rocker shaft, showing a structure for fastening the rocker shaft to a cam holder.

FIG. 4 is an enlarged sectional view taken along line 4-4 of FIG. 1;

FIG. 5 is a refueling system diagram.

FIG. 6 is a cutaway side view showing an oil passage configuration between the control valve means and the first oil supply passage.

FIG. 7 is a sectional view taken along line 7-7 of FIG. 6;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 ... Cylinder head 15 ... Intake valve 16 ... Exhaust valve 23 ... Cam holder 23a ... Bearing hole 24 ... Cam shaft 24a ... Cam journal part 25 ... Rocker shaft 29 ··· Bolt 30 _I ··· Intake side valve mechanism 30 _E ··· Exhaust side valve mechanism 31 and 32 ··· Rocker arm 46 ··· Hydraulic valve operating characteristic changing means 64 ··· First oil supply path 104 ... second oil supply path 105 ... radial oil path 106 ... throttle 107 ... axial oil path 109 ... oil pool

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Noriyuki Sato 1-4-1 Chuo, Wako-shi, Saitama Pref.

Claims (3)

[Claims] A plurality of cam journals (24a) provided on a single camshaft (24) are provided on a plurality of cam holders (23) integrally provided on a cylinder head (11).
Each rotatably supported by a camshaft (24)
And the intake valve (15) the intake-side valve-operating mechanism provided between (30 _I) and the camshaft (24) and exhaust valve (16) the exhaust-side valve-operating mechanism provided between common single to (30 _E) A rocker shaft (25) is fixed to the cylinder head (11) above the camshaft (24), and the intake-side and exhaust-side valve trains (30 _I , 3
0 _E) a plurality of rocker arms whereas (30 _I) constituting to a supported the the rocker shaft (25) of the (31,3
In the SOHC type internal combustion engine in which the hydraulic valve operating characteristic changing means (46) is provided in (2), the cam holder (2)
3) are formed with bearing holes (23a) for inserting and supporting the respective cam journal portions (24a), lubricating portions of the intake side and exhaust side valve trains (30 _I , 30 _E ) and the hydraulic type. A single first oil supply passage (64) extending in the axial direction of the rocker shaft (25) connected to the valve operating characteristic changing means (46) is provided in the rocker shaft (25), and the first oil supply passage (64) is provided. ), The rocker shaft (25) is fastened to the upper surface of each cam holder (23) by a bolt (29) screwed into each of the cam holders (23), and the inner surface of each bearing hole (23a) and each cam journal. Second to guide the oil between the outer surfaces of the portion (24a)
An oil supply path (104) is provided on each bolt (29) with one end thereof communicating with the first oil supply path (64), and at least a part of the cross-sectional area of the second oil supply path (104) is equal to the first oil supply path (64). 64) The SOHC type internal combustion engine, which is set to be smaller than the cross-sectional area. 2. A radial oil passage (105), the second oil passage (104) extending along the radial direction of the bolt (29) with an outer end communicating with the first oil passage (64); An axial oil passage (10) having an upper end communicating with the inner end of the radial oil passage (105) and being formed longer than the radial oil passage (105) along the axial direction of the bolt (29).
The SOHC internal combustion engine according to claim 1, wherein a throttle (106) is formed in the radial oil passage (105). 3. A second oil supply passage (10) between a lower end of the bolt (29) and an outer surface of the cam journal portion (24a).
3. The SOHC according to claim 1, wherein an oil reservoir (109) having a larger diameter than that of (4) is formed.
Type internal combustion engine.