JP2006328989A - Valve gear of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily perform replacing work of a shim detachably installed on the upper end of an engine valve, in a valve gear of an internal combustion engine allowed to abut on the shim for detachably installing a rocker arm rockably supported by a rocker shaft arranged on a cylinder head and driven by a valve system cam, on the upper end of a stem of the engine valve. <P>SOLUTION: A position regulating means 32 can switch a state of being installed on the rocker shaft 33 for determining a position of the rocker arms 29 and 30 in the direction along the axis of the rocker shaft 33 for allowing the rocker arms 290 and 30 to abut on the shim 26 and a state of being removed from the rocker shaft 33 for moving the rocker arms 29 and 30 along the axis of the rocker shaft 33 for releasing abutment on the shim 26; and is detachably installed on the rocker shaft 33. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an internal combustion engine in which a rocker arm that is swingably supported by a rocker shaft provided in a cylinder head and that is driven by a valve cam is abutted against a shim that is detachably mounted on an upper end of a stem of an engine valve. The present invention relates to a valve gear.

The tappet screw that is screwed to the rocker arm that is swingably supported by the rocker shaft is in contact with the upper end of the engine valve, and the valve clearance of the engine valve is adjusted by adjusting the advance / retreat position of the tappet screw. A valve operating apparatus for an internal combustion engine is known from, for example, Patent Document 1, and a rocker arm supported so as to be swingable by a rocker shaft is brought into contact with a shim that is detachably mounted on an upper end of the engine valve. For example, Patent Document 2 discloses a valve operating apparatus for an internal combustion engine in which the valve clearance of an engine valve is adjusted by exchanging the valve.
JP 2003-97227 A JP-A-8-193507

  However, as disclosed in Patent Document 1, the structure in which the tappet screw is screwed to the rocker arm may increase the weight of the valve operating system, which may cause deterioration in the high-speed followability. When the load of the valve spring for increasing the follow-up performance is increased, the friction loss is increased. In addition, it is necessary to secure a free space above the rocker arm for placing the tool for operating the tappet screw, and the valve operating device configured to place the cam above the rocker arm reduces the degree of freedom in cam placement. End up.

  On the other hand, as disclosed in Patent Document 2, in the configuration in which the shim attached to the upper end of the engine valve is replaced while changing its thickness, the weight of the valve operating system is not increased. It is not necessary to secure a free space above the rocker arm, but after measuring the valve clearance after assembly of the valve gear, disassemble the valve gear and replace the shim, or open the engine valve with a special tool. It is necessary to replace the shim while being pushed down to the valve side, and it is difficult to say that the workability of the shim replacement work is excellent.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a valve operating apparatus for an internal combustion engine that can easily replace a shim that is detachably attached to the upper end of an engine valve. And

  In order to achieve the above object, according to the first aspect of the present invention, a rocker arm that is swingably supported by a rocker shaft provided in a cylinder head and that is driven by a valve cam is detachable from an upper end of a stem of an engine valve. In a valve operating apparatus for an internal combustion engine that is in contact with a shim mounted on the rocker, the rocker shaft is mounted on the rocker shaft to determine the position of the rocker arm in a direction along the axis of the rocker shaft so that the rocker arm is in contact with the shim. A position restricting means capable of switching between a state in which the rocker arm is removed and a state in which the rocker arm is removed from the rocker shaft so that the rocker arm can be moved along the axis of the rocker shaft so as to release contact with the shim. The rocker shaft is detachably mounted.

  According to a second aspect of the invention, in addition to the configuration of the first aspect of the invention, the position restricting means includes an oil supply passage that guides oil pressure from an oil passage provided in the rocker shaft to the rocker arm. The rocker shaft is detachably mounted.

  According to a third aspect of the present invention, in addition to the configuration of the first aspect of the invention, the position restricting means can be divided into two on a plane including the axis of the rocker shaft, and It is characterized in that it is a cylindrical collar that is detachably mounted on the rocker shaft so as to determine the position of the rocker arm in a direction along the axis of the rocker shaft when mounted.

  In addition to the structure of the invention described in claim 1, the invention according to claim 4 is characterized in that the position of the rocker arm in the direction along the axis of the rocker shaft is determined when the rocker shaft is mounted. The clip is detachably attached to the head.

  According to the first aspect of the present invention, by removing the position restricting means from the rocker shaft, the rocker arm can be moved along the axis of the rocker shaft to the position where the contact with the shim is released, and the valve clearance is adjusted. Therefore, it is possible to easily replace the shim attached to the upper end of the engine valve while changing its thickness.

  According to the second aspect of the present invention, the position restricting means has an oil supply passage that guides the oil pressure to the rocker arm. By removing the position restricting means from the rocker shaft, the shim can be easily replaced. In addition, it is possible to check the clogging of the oil supply passage at the same time, and the work efficiency is improved.

  Furthermore, according to the third or fourth aspect of the invention, the structure for facilitating the shim replacement work is simplified.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples of the present invention shown in the accompanying drawings.

  1 to 7 show a first embodiment of the present invention. FIG. 1 is a longitudinal side view of a main part of an internal combustion engine. FIG. 2 is a view from the direction of arrow 2 in FIG. 1 with a head cover and a camshaft omitted. FIG. 3 is a partially cutaway plan view seen from the same direction as FIG. 2, FIG. 4 is a sectional view taken along line 4-4 of FIG. 3, and FIG. 5 is a sectional view taken along line 5-5 of FIG. 6 is a sectional view taken along line 6-6 in FIG. 3, and FIG. 7 is a plan view corresponding to FIG. 2 when the shim is replaced.

  1, the cylinder head 12 to which the head cover 11 is coupled faces a pair of intake valve ports 15 facing the ceiling surface of the combustion chamber 14 with the spark plug 13 facing the center and the combustion chamber 14. A pair of exhaust valve ports 17... And both intake valve ports 15... Are connected to the intake port 16 that opens to one side wall of the cylinder head 12. Both exhaust valve ports 17. An exhaust port 18 that opens to the side wall is provided for each cylinder.

  The cylinder head 12 is provided with a guide cylinder 20 that guides the stem 19a of the intake valve 19 that can open and close the intake valve port 15 in the opening and closing operation direction. Is driven to open and close.

  The cylinder head 12 is provided with a guide cylinder 22 for guiding the stem 21a of the exhaust valve 21 as an engine valve capable of opening and closing the exhaust valve port 17 in the opening / closing operation direction. The stem 21a of the exhaust valve 21 is provided. The exhaust valve 21 is placed in the valve closing direction between the spring receiving member 23 fixed to the upper part of the ... and the spring receiving member 24 surrounding the guide tube 22 and abutting against the upper surface of the cylinder head 12. The urging valve springs 25 are contracted.

  Moreover, a bottomed cylindrical shim 26 is detachably attached to the upper end of the stem 21a of the exhaust valve 21, and the valve clearance of the exhaust valve 21 is changed by changing the thickness of the closed end of the shim 26. Will be adjusted.

  2 and 3, the valve operating device that opens and closes the exhaust valves 21... Includes first and second low-speed rocker arms 29 and 30 that individually correspond to the pair of exhaust valves 21. , 30, a high-speed rocker arm 31 sandwiched between, a first low-speed rocker arm 29 between the high-speed rocker arm 30 and a refueling rocker arm 32 as position restricting means, and the rocker arms 29 to 32 are rocked at their base ends. A rocker shaft 33 that can be moved and supported in common, first and second low-speed cams 34 and 35 that individually correspond to the first and second low-speed rocker arms 29 and 33, and a high-speed that corresponds to the high-speed rocker arm 30. A camshaft 37 having a cam 36, and connection of the first and second low-speed rocker arms 29, 30 to the high-speed rocker arm 31; And a coupling switching mechanism 38 for switching the binding release.

  The rocker shaft 33 and the camshaft 37 have axes parallel to each other, and the rocker shaft 33 is located on the cylinder head 12 at positions corresponding to both sides of the combustion chamber 14 along the axis of the rocker shaft 33. The camshaft 37 is rotatably supported by the holders 39 and 39, and the caps 40 and 40 fastened to the holders 39, respectively. .

  Further, cylindrical boss portions 39a surrounding the rocker shaft 33 are integrally projected on one side surface of the holders 39, and the base end portions of the rocker arms 29 to 32 are formed on the rocker shaft 33. It is sandwiched between the other side surface of the holder 39 disposed on one side of the combustion chamber 14 along the axis and the boss portion 39a of the holder 39 disposed on the other side of the combustion chamber 14 along the axis of the rocker shaft 33. Thus, the position along the axis of the rocker shaft 33 is determined.

  In FIG. 4, a tip 41 made of a wear-resistant material is fixed to the tip of the first low-speed rocker arm 29 so as to abut on a shim 26 attached to the upper end of the stem 21a of the exhaust valve 21. The Further, a groove 42 opened on the camshaft 37 side is provided in an intermediate portion of the first low-speed rocker arm 29, and a roller 43 that is disposed in the groove 42 and makes rolling contact with the first low-speed cam 34 is provided. It is pivotally supported via a needle bearing 45 on a cylindrical first sleeve 44 having an axis parallel to the camshaft 37 and fixed to the first low-speed rocker arm 29.

  A tip (not shown) made of wear-resistant material is also fixed to the tip of the second low-speed rocker arm 30 so as to abut on a shim 26 mounted on the upper end of the stem 21a of the exhaust valve 21. A roller 47 disposed in a groove 46 provided in an intermediate portion of the second low-speed rocker arm 30 and making rolling contact with the second low-speed cam 35 has an axis parallel to the camshaft 37 and has a second low-speed. A cylindrical second sleeve 48 fixed to the rocker arm 30 is pivotally supported via a needle bearing 49.

  In FIG. 5, a groove 50 opened on the camshaft 37 side is provided at the tip of the high-speed rocker arm 31, and a roller 51 disposed in the groove 50 and making rolling contact with the high-speed cam 36 It is pivotally supported via a needle bearing 53 on a cylindrical third sleeve 52 having an axis parallel to the shaft 37 and fixed to the rocker arm 31 for high speed.

  In addition, a tip 54 made of a wear-resistant material is fixed to the lower portion on the tip side of the high-speed rocker arm 31. On the other hand, a lost motion mechanism 55 clearly shown in FIG. 1 is arranged in the cylinder head 12 below the high-speed rocker arm 31 at a fixed position. Thus, the lost motion mechanism 55 includes a lifter 56 that contacts the tip 54 of the high-speed rocker arm 31, a closed end of the bottomed hole 57 provided in the cylinder head 12 so as to open upward, and the lifter 56. The high-speed rocker arm 31 is urged toward the side where the roller 51 is slidably contacted with the high-speed cam 36 by the spring force exerted by the lost motion spring 58. The

  In FIG. 6, the oil supply rocker arm 32 is fastened by a pair of bolts 63, 63 in which first and second members 61, 62 having a plane including the axis of the rocker shaft 33 as a coupling surface are arranged on both sides of the rocker shaft 33. It can be removed from the rocker shaft 33 by releasing the fastening state by the bolts 63.

  The first member 61 is connected to the arc portion 61a covering the upper half of the rocker shaft 25, an extension portion 61b extending from the arc portion 61a toward the exhaust valve 21, and a tip of the extension portion 61b. And a cylindrical fitting cylinder portion 61c that is integrated with one end portion of the first sleeve 44 of the first low-speed rocker arm 29. On the other hand, the second member 62 is formed in an arc shape covering the lower half portion of the rocker shaft 33, and both sides of the arc portion 61 a of the first member 61 are fastened to both sides of the second member 62 with bolts 63.

  Thus, in the oil supply rocker arm 32 in which the first and second members 61 and 62 are coupled so that the rocker shaft 33 is sandwiched from both sides, the fitting cylinder portion 61c is in the first low-speed rocker arm when coupled to the rocker shaft 33. 29, the first low-speed rocker arm 29 and the first low-speed rocker arm 29 oscillate integrally. When the oil supply rocker arm 32 is removed from the rocker shaft 33, a portion corresponding to the oil supply rocker arm 32 becomes empty. Due to the space, the first low-speed rocker arm 29, the high-speed rocker arm 31 and the second low-speed rocker arm 30 can be moved along the axis of the rocker shaft 33, as shown in FIG. The first low-speed rocker arm 29 is moved from the shim 26 at the upper end of the stem 21a of one exhaust valve 21. The second low-speed rocker arm 30 can be slid to a position disengaged from the shim 26 at the upper end of the stem 21a of the other exhaust valve 21, and the shims 26 can be replaced in this state. Easy.

  As shown in FIG. 7, the first low-speed rocker arm 29, the high-speed rocker arm 31 and the second low-speed rocker arm 30 are moved along the axis of the rocker shaft 33 to the lifter 56 of the lost motion mechanism 55. It is necessary that a part of the tip 54 of the high-speed rocker arm 31 is overlapped. Then, the first low-speed rocker arm 29, the high-speed rocker arm 31 and the second low-speed rocker arm 30 are connected to the axis of the rocker shaft 33. , The high-speed rocker arm 31 and the lost motion mechanism 55 are not caught, and each rocker arm 29 to 31 can be smoothly returned to the original position.

  3, the first sleeve 44 of the first low-speed rocker arm 29, the third sleeve 52 of the high-speed rocker arm 31, and the second sleeve 48 of the second low-speed rocker arm 30 are in the closed state of the exhaust valve 21. Are both of the same inner diameter arranged on the same axis so that both ends thereof are located at corresponding positions between the first low speed rocker arm 29, the high speed rocker arm 31 and the second low speed rocker arm 30, The connection switching mechanism 38 is disposed in the sleeves 44, 48, 52.

  Thus, the connection switching mechanism 38 allows one end to face the hydraulic chamber 64 and allows the other end side to be fitted to the third sleeve 52 of the high speed rocker arm 31 so that the first sleeve 44 of the first low speed rocker arm 29 can be fitted. The first connecting pin 65 is slidably fitted to the first connecting pin 65, and one end is brought into contact with the other end of the first connecting pin 65, and the other end is fitted to the second sleeve 48 of the second low-speed rocker arm 30. The second connecting pin 66 slidably fitted to the third sleeve 52 and the snap ring 67 and the second connecting pin 66 mounted on the second sleeve 48 so as to be slidably fitted to the third sleeve 52. A return spring 68 for urging the second connecting pins 65 and 66 toward the hydraulic chamber 64 is provided.

  The hydraulic chamber 64 is formed in the first sleeve 44 between one end of the first connecting pin 65 and the fitting cylinder portion 61 c of the oil supply rocker arm 32, and the rocker shaft 33 is formed in the hydraulic chamber 64. The oil supply rocker arm 32 is provided with an oil supply passage 70 for guiding oil pressure from an oil passage 69 provided coaxially therein.

  Paying attention to FIG. 6, the oil supply passage 70 communicates with the communication passage 71 provided in the rocker shaft 33 through the oil passage 69 in the rocker shaft 33 so as to always communicate with the communication hole 71 regardless of the rocking of the oil supply rocker arm 32. A concave portion 70a provided on the inner periphery of the arc portion 61a of the first member 61, a first oil passage portion 70b provided in the extension portion 61b so as to communicate with the concave portion 70a, and a first oil passage portion 70b. Thus, the second oil passage portion 70c is provided in the fitting cylinder portion 61c, and the second oil passage portion 70c communicates with the hydraulic chamber 64.

  Thus, when high hydraulic pressure from the oil passage 69 is guided to the hydraulic chamber 64, the first connecting pin 65 has the other end side against the spring force of the return spring 68 and the third sleeve 52 of the high-speed rocker arm 31. The second connecting pin 66 pushed by the first connecting pin 65 moves so that the other end of the second connecting pin 66 is fitted to the second sleeve 48 of the second low-speed rocker arm 30, and the first low-speed rocker arm 29 is moved. Are connected to the high-speed rocker arm 31 via the first connecting pin 65, and the high-speed rocker arm 31 is connected to the second low-speed rocker arm 30 via the second connecting pin 66. As a result, the first and second low-speed rocker arms 29 and 30 are connected to the high-speed rocker arm 31, and the first and second low-speed rocker arms 31 together with the high-speed rocker arm 31 that swings following the high-speed cam 36. 29 and 30 swing, and the pair of exhaust valves 21 are driven to open and close with operating characteristics corresponding to high-speed operation.

  On the other hand, when the oil pressure in the oil passage 69 in the rocker shaft 33 is released and the oil pressure in the hydraulic chamber 64 is lowered, the second connecting pin 66 is moved by the third sleeve 52 of the high-speed rocker arm 31 by the spring force of the return spring 68. The first connecting pin 65 is returned to a position where the entire length is accommodated in the first sleeve 44 of the first low-speed rocker arm 29. In this state, the connection state of the high-speed rocker arm 31 to the first and second low-speed rocker arms 29 and 30 is released, and the first and second low-speed rocker arms 29 and 30 correspond to the corresponding first and second low-speed cams. Accordingly, the pair of exhaust valves 21 are driven to open and close with operating characteristics corresponding to low-speed operation.

  As shown in FIG. 4, an oil jet 72 directed toward the tip 41 is provided at the base of the first and second low-speed rocker arms 29 and 30 below the rocker shaft 33. A communication hole 73 is provided for communicating the oil passage 69 therein with the oil jet 72, and oil from the oil passage 69 is ejected to the contact portion between the tip 41 and the shim 26 through the oil jet 72. As a result, the friction and wear between the tip 41 and the shim 26 are reduced.

  Further, as shown in FIG. 5, in the high-speed rocker arm 31, oil accumulated in the groove 50 in which the roller 51 is disposed is supplied to the tip 54 fixed to the lower portion of the high-speed rocker arm 32 and the lifter of the lost motion mechanism 55. An oil supply hole 74 that leads to a contact portion with the tip 56 is provided, and the oil in the groove 50 is guided to the contact portion between the tip 54 and the lifter 56, thereby causing friction and wear between the tip 54 and the lifter 56. Can be reduced.

  Next, the operation of the first embodiment will be described. Shims in which chips 41 fixed to the first and second low-speed rocker arms 29, 30 are detachably mounted on the upper ends of the stems 21a of the exhaust valves 21. 26, a state in which the first and second low-speed rocker arms 29 and 30 are positioned in the direction along the axis of the rocker shaft 33 so as to be in contact with the rocker shaft 33; The first and second low-speed rocker arms 29 and 30 can be switched from a state where they are removed from the rocker shaft 33 so that the first and second low-speed rocker arms 29 and 30 can be moved along the axis of the rocker shaft 33. An oil supply rocker arm 32 is detachably attached to the rocker shaft 33.

  Therefore, by removing the oil supply rocker arm 32 from the rocker shaft 33, the first and second low speed rocker arms 29 and 30 can be moved along the axis of the rocker shaft 33 to a position where the contact with the shims 26 is released. Further, it is possible to easily replace the shims 26 attached to the upper ends of the exhaust valves 21 to adjust the valve clearance while changing the thickness thereof.

  The oil supply rocker arm 32 has an oil supply passage 70 that guides the oil pressure to the first low-speed rocker arm 29. By removing the oil supply rocker arm 32 from the rocker shaft 25, the replacement work of the shims 26 is facilitated. In addition, it is possible to check for clogging of the oil supply passage 70 at the same time, thereby improving work efficiency.

  FIG. 8 shows a second embodiment of the present invention, and the same reference numerals are given to portions corresponding to the first embodiment.

  The second embodiment is applied when the distance between the holders 39 and 39 can be set larger than that of the first embodiment. Between the holders 39 and 39, the second embodiment is applied. The first low-speed rocker arm 29 ', the second low-speed rocker arm 30, and the high-speed sandwiched between these low-speed rocker arms 29', 30 are formed in a shape that combines the first low-speed rocker arm 29 and the oil supply rocker arm 32. A rocker arm 31 and a cylindrical collar 76 are disposed as position restricting means for sandwiching the first low speed rocker arm 29 ′ between the high speed rocker arm 30.

  The collar 76 surrounds the rocker shaft 33 so that it can be divided into two on a plane including the axis of the rocker shaft 33. When the collar 76 is removed from the rocker shaft 33, the collar 76 is the same as in the first embodiment. The first and second low-speed rocker arms 29 ', 30 can be moved along the axis of the rocker shaft 33 to a position where the contact with the shims 26 is released, and the exhaust valve 21 ... can be adjusted to adjust the valve clearance. It is possible to easily replace the shims 26 attached to the upper ends of the plates while changing the thickness thereof, and the structure for facilitating the replacement of the shims 26 is simplified.

  As a third embodiment of the present invention, as shown in FIG. 9, a clip 77 as a position restricting means that contacts and engages with the first low-speed rocker arm 29 ′ on the side opposite to the high-speed rocker arm 31, Instead of the collar 76 of the embodiment, it may be detachably mounted on the rocker shaft 33, and the same effect as that of the second embodiment can be obtained by the third embodiment.

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

  For example, in the above embodiment, the exhaust valve 21 has been described. However, the present invention can also be implemented in connection with the intake valve. It is also possible to implement the present invention in connection with a rocker arm that is not equipped with the connection switching mechanism 38.

It is a principal part vertical side view of the internal combustion engine of 1st Example. FIG. 2 is a plan view seen from the direction of arrow 2 in FIG. 1 with the head cover and camshaft omitted. FIG. 3 is a partially cut plan view seen from the same direction as FIG. 2. FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. FIG. 5 is a sectional view taken along line 5-5 of FIG. FIG. 6 is a sectional view taken along line 6-6 of FIG. FIG. 3 is a plan view corresponding to FIG. 2 when a shim is replaced. It is a top view corresponding to FIG. 2 of 2nd Example. It is a top view corresponding to FIG. 2 of 3rd Example.

Explanation of symbols

12 ... Cylinder head 21 ... Exhaust valve 21a which is an engine valve ... Stem 26 ... Shim 29, 29 ', 30 ... Rocker arm 32 ... Oil supply rocker arm 33 as position restricting means · Rocker shafts 34, 35 ... cam 69 ... oil passage 70 ... oil supply passage 76 ... collar 77 as position restricting means ... clip as position restricting means

Claims (4)

  A rocker arm (29, 30; 29 '), which is swingably supported by a rocker shaft (33) provided in the cylinder head (12) and is driven by a cam (34, 35), is a stem ( 21a) In a valve operating apparatus for an internal combustion engine that is in contact with a shim (26) that is detachably mounted on the upper end of 21a), the rocker arm (29, 30; 29 ') is in contact with the shim (26). The state where the rocker shaft (33) is mounted to determine the position of the rocker arm (29, 30; 29 ') in the direction along the axis of the rocker shaft (33) and the contact with the shim (26) are released. The rocker arm (29, 30; 29 ') is disconnected from the rocker shaft (33) so that the rocker arm (29, 30; 29') can be moved along the axis of the rocker shaft (33). E possible and position regulating means (32,76,77) is a valve gear of an internal combustion engine characterized by detachably mounted is that the rocker shaft (33).   The position restricting means (32) has an oil supply passage (70) for guiding hydraulic pressure from an oil passage (69) provided in the rocker shaft (33) to the rocker arm (29), and is provided on the rocker shaft (33). 2. The valve operating apparatus for an internal combustion engine according to claim 1, wherein the valve operating apparatus is detachably mounted.   While the position restricting means (76) can be divided into two on a plane including the axis of the rocker shaft (33), the position restricting means (76) is aligned with the axis of the rocker shaft (33) when mounted on the rocker shaft (33). 2. An internal combustion engine according to claim 1, wherein the rocker arm (29 ', 30) is a cylindrical collar that is detachably mounted on the rocker shaft (33) so as to determine the position of the rocker arm (29', 30) along the direction. Valve operating device.   When the rocker shaft (33) is mounted on the rocker shaft (33), the position restricting means (77) determines the position of the rocker arm (29 ', 30) in a direction along the axis of the rocker shaft (33). The valve operating apparatus for an internal combustion engine according to claim 1, wherein the clip is detachably attached to (33).

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