JP4381965B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine.

Conventionally, as such an internal combustion engine, a plurality of intake valves that have an interlocking switching mechanism capable of switching between interlocking and unlocking between the camshaft and the intake valve and driving the intake valve in conjunction with the rotation of the camshaft. The drive member is disposed so as to be swingable via a swing support shaft, and the interlocking switching mechanism is switched with a switching pin movable between a position where the adjacent intake valve driving member is interlocked and a position where the interlock is released. And a cylindrical shaft member fixed to the intake valve drive member for guiding the movement of the pin, and a cylindrical rotating body that is in sliding contact with the cam provided on the camshaft rotates. The specific intake valve drive member of the plurality of intake valve drive members is freely supported with respect to the intake valve when the interlock switching mechanism is in the interlock release state, and the specific intake valve drive Lost motion parts It is that so as to resiliently urging the cam side mechanism is already known (for example, the following Patent Document 1).
JP-A-63-110091

  By the way, in the internal combustion engine as described above, a specific motion of the plurality of intake valve drive members is integrally formed with a lost motion mechanism receiving portion that engages with the lost motion mechanism.

  It is an object of the present invention to effectively increase the support rigidity of a cylindrical shaft member in the specific intake valve driving member using the lost motion mechanism receiving portion.

In order to achieve the above object, the present invention has an interlocking switching mechanism capable of switching interlocking and interlocking release between a camshaft and an intake valve, and drives the intake valve in conjunction with the rotation of the camshaft. A plurality of intake valve drive members are swingably disposed via a swing support shaft, and the interlock switching mechanism is movable between a position where the adjacent intake valve drive members are interlocked and a position where the interlock is released. A switching pin and a cylindrical shaft member fixed to the intake valve driving member for guiding the movement of the switching pin are provided, and each cylindrical shaft member has a cylindrical shape slidably contacting a cam provided on the camshaft. The rotary body is rotatably supported, and a specific intake valve drive member of the plurality of intake valve drive members is free with respect to the intake valve when the interlock switching mechanism is in the interlock release state. The intake valve drive member of During the internal combustion engine so as to resiliently urging the cam side Shon mechanism, and certain of the cam corresponding to the specific intake valve driving member, said lost motion mechanism, the specific intake valve driving member The specific intake valve drive member is disposed opposite to each other , and the specific intake valve drive member directly receives the lost motion mechanism around the specific rotary body corresponding to the specific intake valve drive member. parts are integrally projects, the lost motion mechanism receiving portion in the opposing face of the cross that is directly engaged with the lost motion mechanism receiving portion and a lost motion mechanism, the width of the cam shaft axis direction, the lost motion mechanism side of the width is set smaller than a cam shaft axis direction of the width of the size rather and the specific rotary member than further wherein the width of the particular rotating body, of the specific Characterized in that it is set to be smaller than the camshaft axis direction of the width of the beam.

  As described above, according to the present invention, the width in the camshaft axial direction of the lost motion mechanism receiving portion on the mutually facing surfaces where the lost motion mechanism receiving portion and the lost motion mechanism directly engage with each other is Since it is larger than the width, it is possible to effectively increase the support rigidity of the cylindrical shaft member in the intake valve driving member by using the lost motion mechanism receiving portion that is so strong.

  Embodiments of the present invention will be specifically described below based on the embodiments of the present invention illustrated in the accompanying drawings.

  1 to 5 show an embodiment of the present invention, FIG. 1 is a side view of a V-type internal combustion engine, and FIG. 2 is an enlarged sectional view taken along line 2-2 in FIG. 3 is a sectional view taken along line 3-3 in FIG. 2, FIG. 4 is a sectional view taken along line 4-4 in FIG. 2, and FIG. 5 is a sectional view taken along line 5-5 in FIG.

  First, in FIG. 1, the V-type internal combustion engine is arranged in one or a plurality of cylinders 7 aligned in the axial direction of the crankshaft 6 and a substantially V-shape opened upward with respect to the cylinders 7. One or a plurality of cylinders 7 arranged in the direction are provided in the cylinder block 8, and the cylinder heads 9, 9 coupled to the cylinder block 8 are connected to the intake port 10 of each cylinder 7. And the exhaust ports 11 of the cylinders 7 are provided on the outer side of the V-shape, and the intake manifold M connected to the intake ports 10 is disposed between the cylinder heads 9 and 9. It is.

  2 to 4 together, a piston 12 is slidably fitted into the cylinder 7, and a combustion chamber 13 is formed between the upper surface of the piston 12 and the cylinder head 9. The cylinder head 9 is provided with a pair of intake valve ports 14 and a pair of exhaust valve ports 15 so as to open to the ceiling surface of the combustion chamber 13, and both intake valve ports 14 are connected to the intake port 10. The two exhaust valve ports 15... Are communicated with the exhaust port 11.

  A pair of intake valves 16, 16 capable of individually opening and closing both intake valve ports 14 are slidably fitted into guide cylinders 17 provided respectively on the cylinder head 9, and upward from the respective guide cylinders 17. Between the retainers 18 and 18 provided at the upper end portions of the protruding intake valves 16 and 16 and the cylinder head 9, valve springs 19 and 19 surrounding the intake valves 16 and 16 are contracted, and these valve springs 19 are provided. , 19 urge the intake valves 16, 16 in a direction to close the intake valve ports 14. Further, a pair of exhaust valves 20 and 20 capable of individually opening and closing both exhaust valve ports 15 are slidably fitted to guide cylinders 21 provided on the cylinder head 9 respectively, and upward from the respective guide cylinders 21. Between the retainers 22 and 22 provided at the upper ends of the exhaust valves 20 and 20 projecting to the cylinder head 9, valve springs 23 and 23 surrounding the exhaust valves 20 and 20 are contracted, and these valve springs are provided. 23 and 23 urge the exhaust valves 20 and 20 in a direction to close the exhaust valve ports 15.

Between the intake valves 16 and 16 and the camshaft 26 that is linked and connected to the crankshaft 6 at a reduction ratio of 1/2, the rotational movement of the camshaft 26 is changed to the opening and closing movement of the intake valves 16 and 16. provided intake valve driving means 27 ₁ for converting, between the two exhaust valves 20, 20 and the camshaft 26, an exhaust valve for converting a rotary motion of the camshaft 26 to the opening and closing movement of the exhaust valve 20, 20 driven Means 27 ₂ are provided.

  Referring also to FIG. 5, the camshaft 26 is rotatably supported by the cylinder head 9 and a holder 28 coupled to the cylinder head 9, having an axis parallel to the rotation axis of the crankshaft 6. The The camshaft 26 includes an intake valve high-speed cam 29, an intake valve low-speed cam 30 disposed on one side of the intake valve high-speed cam 29 corresponding to one intake valve 16, and an intake valve high-speed cam. 29, the intake valve rest cam 31 disposed on the opposite side of the intake valve low-speed cam 30 and corresponding to the other intake valve 16, and both the intake valve low-speed cam 30 and the intake valve stop cam 31 on both sides. Exhaust valve cams 32, 32 arranged individually corresponding to the exhaust valves 20, 20 are respectively fixed.

The intake valve high-speed cam 29 has a shape for opening and closing both intake valves 16 and 16 in the high-speed operation region of the engine, and includes an arc-shaped base circle portion 29 a centering on the axis of the camshaft 26. And a high-order part 29b projecting outward from the base circle part 29a in the radial direction. The intake valve low-speed cam 30 has a shape for opening and closing one intake valve 16 in the low-speed operation region of the engine, and includes an arc-shaped base circle portion 30a centering on the axis of the camshaft 26; The amount of protrusion of the camshaft 26 radially outward from the base circle portion 30a is smaller than the high position portion 29b of the intake valve high-speed cam 29, and the base circle portion extends over a central angle range narrower than the high position portion 29b. And a high-order part 30b protruding from 30a. The intake valve stop cam 31 has a shape for substantially stopping the other intake valve 16 in the low speed operation region of the engine. Basically, the base circular portion 29a of both the cams 29, 30 is used. , 30a, and the cams 29, 30 corresponding to the high positions 29b, 30b of the cams 29, 30, the intake valve 16 is substantially kept in a resting state. In order to avoid sticking to the intake valve port 14, a protrusion 31 a for slightly opening the valve is provided. Moreover, the width W ₂ along the axial direction of the intake valve low-speed cam 30 is smaller than the width W ₁ of the intake valve high-speed cam 29, and the width W ₃ along the axial direction of the intake valve rest cam 31 is the intake valve low speed. It is smaller than the width W _{2 of the} cam 30. Further, the exhaust valve cams 32, 32 have a shape for opening and closing both the exhaust valves 20, 20 regardless of the operating state of the engine.

On the other hand, the intake valve drive means 27 ₁ includes first, second and third intake valve side rocker arms 33, 34, 35 as intake valve drive members arranged adjacent to each other, and interlocking of these rocker arms 33 to 35. The first intake valve side rocker arm 33 is linked and connected to one intake valve 16, and the third intake valve side rocker arm 35 is connected to the other intake valve 16. The second intake valve side rocker arm 34 that is linked and connected as a specific intake valve driving member is disposed between the first and third intake valve side rocker arms 33 and 35. The first to third intake valve side rocker arms 33 to 35 are swingably supported by an intake valve side rocker arm shaft 37 as a swing support shaft fixedly supported by the holder 28 at a position obliquely above the camshaft 26. The Further, the exhaust valve driving means 27 ₂ has a pair of exhaust valve side rocker arms 38, 38 as exhaust valve driving members that are individually linked and connected to the exhaust valves 20, 20, respectively. 38 is swingably supported by an exhaust valve side rocker arm shaft 39 fixedly supported by the holder 28 at an obliquely upper position of the camshaft 26. The first to third intake valve side rocker arms 33 to 35 are arranged adjacent to each other between the holders 28 and 28 arranged on both sides of the cylinder 7 along the axis of the crankshaft 6. A coil spring 42 surrounding the side rocker arm shaft 39 is disposed between the holders 28 and 28 so as to be interposed therebetween.

The first and third intake valve side rocker arm 33, 35 in the intake valve driving means 27 _1, the arm portion 33a extending in the intake valve 16 and 16 side, 35a are provided integrally, their arms 33a, 35a The tappet screws 40, 40 that abut on the upper ends of the intake valves 16, 16 are screwed to the front ends of the two intake valves 16, 16 so as to freely advance and retract. Also on both exhaust valve side rocker arms 38, 38 in the exhaust valve driving means 27 _2, arms 38a extending in both the exhaust valves 20, 20 side, 38a are provided integrally, their arms 38a, 38a tip of The tappet screws 41 and 41 that are in contact with the upper ends of the exhaust valves 20 and 20 are screwed together so as to be able to advance and retract.

  In the first intake valve side rocker arm 33, a cylindrical rotating body that is in sliding contact with the intake valve low-speed cam 30 is located at the end opposite to the intake valve 16 with respect to the swing axis thereof, that is, the axis of the intake valve side rocker arm shaft 37. 45 is rotatably supported, and the second intake valve side rocker arm 34 has a cylindrical rotation that is in sliding contact with the intake valve high-speed cam 29 at the end opposite to the intake valves 16 and 16 with respect to the swing axis. A body 46 is rotatably supported. In the third intake valve side rocker arm 35, a cylindrical rotary body 47 slidably in contact with the intake valve rest cam 31 is provided at the end of the third intake valve side rocker arm 35 opposite to the intake valve 16. Are rotatably supported, and both exhaust valve side rocker arms 38, 38 are opposite to both exhaust valves 20, 20 with respect to the swing axis thereof, that is, the axis line of the exhaust valve side rocker arm shaft 39. The end cylindrical rotary member 48, 48 in sliding contact is rotatably supported on the exhaust valve cam 32, 32.

  The first intake valve side rocker arm 33 has a bottomed fitting hole 49 opened to the second intake valve side rocker arm 34 side in parallel with the intake valve side rocker arm shaft 37. Are provided with fitting holes 50 opened on both side surfaces corresponding to the fitting holes 49, and the third intake valve side rocker arm 35 is provided on the second intake valve side rocker arm 34 side corresponding to the fitting hole 50. A bottomed fitting hole 51 that is open at the bottom is formed in parallel with the intake valve side rocker arm shaft 37. Thus, cylindrical shaft members 52, 53, and 54 having the same diameter are fitted and fixed in the fitting hole 49, the fitting hole 50, and the fitting hole 51, respectively. A plurality of rollers 55, 56,... 57 are interposed between the rotating bodies 45 to 47 that coaxially surround the cylindrical shaft members 52 to 54, respectively.

  Thus, the second intake valve side rocker arm 34 as a specific intake valve drive member is provided at the end opposite to the intake valve 16 so as to support both ends of the corresponding cylindrical shaft member 53. A pair of support walls 34s, 34s arranged in parallel with the rotating body 46 in between are integrally provided, and the fitting holes 50, 50 are formed in both the support walls 34s, 34s, respectively. Further, on the upper surface of the second intake valve side rocker arm 34, a lost motion mechanism receiving raised portion 34a is integrally formed around the corresponding rotating body 46, and this raised portion 34a is connected to the lost motion mechanism receiving portion. It is configured and directly engages with a lost motion mechanism 62 described later.

The exhaust valve side rocker arms 38, 38 are provided with fitting holes 58, 58 opened on both side surfaces in parallel with the exhaust valve side rocker arm shaft 39, and are fitted and fixed to the fitting holes 58, 58, respectively. A plurality of rollers 60... 60 are respectively interposed between the cylindrical shaft members 59 and 59 and the rotating bodies 48 and 48 that coaxially surround the cylindrical shaft members 59 and 59. Accordingly, the first to third intake valve side rocker arms 33 to 35 are slidably contacted with the corresponding cams 30, 29, and 31 via the rotating bodies 45 to 47. In addition, since the width W _{1 of the} intake valve high-speed cam 29> the width W _{2 of the} intake valve low-speed cam 30> the width W ₃ of the intake valve stop cam 31, the axial length of the rotating body 46> the rotating body 45. Axial length> Axial length of the rotator 47 is set. Further, the exhaust valve side rocker arms 20 and 20 are slidably contacted with the exhaust valve cams 32 and 32 via the rotating bodies 48 and 48, respectively.

  A support plate 61 is fixed on the holder 28 over the intake valve side rocker arms 33 to 35 and the exhaust valve side rocker arms 38, 38, and the second intake valve side rocker arm 34 is attached to the support plate 61. A lost motion mechanism 62 is provided for elastically energizing the rotating body 46 in a direction in which the rotating body 46 is slidably in contact with the intake valve high-speed cam 29. The lost motion mechanism 62 is formed in a bottomed cylindrical shape that opens downward, and is supported by a support plate 61 A guide member 63 that is fixed to the second intake valve side, a lifter 64 that is slidably fitted to the guide member 63 with its tip abutted against the second intake valve side rocker arm 34, and is contracted between the lifter 64 and the guide member 63. The lifter spring 65 is provided.

As is apparent from FIGS. 4 and 5, the camshaft of the lost motion mechanism receiving raised portion 34a on the mutually opposing surfaces where the raised portion 34a of the lost motion mechanism receiving portion and the lifter 64 of the lost motion mechanism 62 directly engage with each other. The width in the axial direction is larger than the width in the camshaft axial direction on the lift 64 side, and the cylinder in the second intake valve side rocker arm 34 is utilized by using the bulged portion 34a for receiving the lost motion mechanism. The support rigidity of the shaft member 53 can be effectively increased. Moreover, the width of the raised portion 34a for receiving the lost motion mechanism is set to be smaller than the width of the rotating body 46 in the camshaft axial direction, and the width of the rotating body 46 is the camshaft of the high-speed cam 29 for the intake valve. It is set smaller than the width in the axial direction.

  The interlocking switching mechanism 36 is interlocked and interlocked between the first switching pin 68 capable of switching interlocking and interlocking release of the third and second intake valve side rocker arms 35 and 34 and the second and first intake valve side rocker arms 34 and 33. A second switching pin 69 capable of switching release, a regulating member 70 slidably contacting the second switching pin 69 on the side opposite to the first switching pin 68, and a return for biasing the regulating member 70 toward the second switching pin 69 And a spring 71.

  The first switching pin 68 is slidably fitted to the cylindrical shaft member 54 of the third intake valve side rocker arm 35, and is connected to the closed end of the fitting hole 51 in the third intake valve side rocker arm 35. A hydraulic chamber 72 is defined between the one switching pin 68. The third intake valve side rocker arm 35 is provided with a communication path 73 that communicates with the hydraulic pressure chamber 72, and the intake valve side rocker arm shaft 37 is provided with a hydraulic pressure path 74 that always communicates with the communication path 73. Thus, the fluid pressure path 74 is connected to a fluid pressure source via a control valve (not shown).

  The second switching pin 69 is slidably fitted to the cylindrical shaft member 53 of the second intake valve side rocker arm 34, and one end of the second switching pin 69 is in sliding contact with the first switching pin 68.

  The restricting member 70 is formed in a bottomed cylindrical shape and is slidably fitted to the cylindrical shaft member 52 of the first intake valve side rocker arm 33, and the closed end of the restricting member 70 is second switched. The other end of the pin 69 is slidably contacted. A retaining ring 75 is fitted on the inner surface of the cylindrical shaft member 52 so as to abut against the regulating member 70 and prevent the regulating member 70 from falling off the cylindrical shaft member 52. The return spring 71 is contracted between the closed end of the fitting hole 49 in the first intake valve side rocker arm 33 and the regulating member 70, and an open hole 76 is formed in the closed end of the fitting hole 49. .

Incidentally, a spark plug 78 is disposed at the center of the ceiling surface of the combustion chamber 13, and a plug pipe 79 for inserting the spark plug 78 is disposed in the cylinder head 9. In Thus with an intake valve drive unit 27 _1, the cam shaft 26 through the rotating body 45 to 47 on the opposite side of the intake valves 16, 16 for each intake valve side rocker arm 33 to 35 intake valve side rocker arm shaft 37 Since the interlock switching mechanism 36 is slidably contacted with each of the cams 30, 29, and 31 and is disposed coaxially with the rotating bodies 45 to 47, the arms of the first and third intake valve side rocker arms 33 and 35 are arranged. There is an empty space between the portions 33a and 35a, and the plug pipe 79 can be disposed in the empty space. Therefore, in the in-vehicle V-type internal combustion engine in which the intake side is arranged on the inner side, the plug pipe 79 for attaching / detaching the spark plug 78 can be arranged on the inner side of the V-type internal combustion engine.

  Next, the operation of this embodiment will be described. In the low-speed operation region of the engine, no hydraulic pressure is applied to the hydraulic chamber 72 of the interlocking switching mechanism 36, and the first and second switching pins 68 and 69 are in sliding contact. The surface is located at a position corresponding to between the third and second intake valve side rocker arms 34, 35, and the sliding surface of the second switching pin 69 and the regulating member 70 is between the second and first intake valve side rocker arms 34, 33. In the corresponding position. Accordingly, the intake valve side rocker arms 33 to 35 are in a relatively swingable state, and one intake valve 16 is driven to open and close at a timing and lift amount corresponding to the intake valve low-speed cam 30, whereas the other intake valve 16 is driven. Valve 16 is substantially deactivated.

  In the high-speed operation region of the engine, a high hydraulic pressure is applied to the hydraulic chamber 72 of the interlocking switching mechanism 36, and the first switching pin 68 presses the second switching pin 69 and the cylinder of the second intake valve side rocker arm 34. The second switching pin 69 is fitted to the cylindrical shaft member 52 of the first intake valve side rocker arm 33 while pressing the regulating member 70. Therefore, the first to third intake valve side rocker arms 33 to 35 are integrally connected, and the intake valves 16 and 16 are opened and closed at a timing and lift amount corresponding to the intake valve high-speed cam 29. Become.

  In this way, by changing the opening / closing operation characteristics of the intake valves 16, 16 in the low speed operation range and the high speed operation range of the engine, it is possible to improve the engine output as a valve operating characteristic adapted to the operating state of the engine. .

  On the other hand, both the exhaust valves 20 and 20 are driven to open and close at a timing and a lift amount corresponding to the exhaust valve cams 32 and 32 in both the low speed operation region and the high speed operation region of the engine.

In such a valve operating apparatus, the intake valve driving means 27 ₁ and the exhaust valve driving means 27 ₂ have their respective rocker arms 33 to 35, 38, 38 via the rotating bodies 45 to 47, 48, 48 and corresponding cams 30, Since it is slidably contacted with 29, 31, 32, 32, it is possible to reduce friction loss and reduce valve opening power. The interlocking switching mechanism 36 provided in the first to third intake valve side rocker arms 33 to 35 is arranged coaxially with the rotating bodies 45 to 47, and switching pins 68 and 69 constituting the interlocking switching mechanism 36. The regulating member 70 and the return spring 71 are inserted into the cylindrical shaft members 52 to 54 provided on the rocker arms 33 to 35 so as to support the rotating bodies 45 to 47, so that the interlocking switching mechanism 36 is configured. It is not necessary to perform the drilling process on each of the rocker arms 33 to 35, which can contribute to a reduction in the number of processing steps.

  In addition, since the spark plug 78 can be arranged on the intake valves 16 and 16 side, the heat drawability around the spark plug 78 can be improved, and the ignition timing of the spark plug 78 is set in the vicinity of the ignition timing that generates the maximum torque. Even if it is set, the occurrence of knocking can be suppressed, so that a sufficient output torque can be obtained.

  Further, in the in-vehicle V-type internal combustion engine in which the intake side is disposed on the inner side, the spark plug 78 is disposed on the intake valves 16 and 16 side, so that a space for detaching the spark plug 78 is provided in the V-type internal combustion engine. What is necessary is just to ensure above, and it becomes easy to ensure the space for attachment / detachment of the spark plug 78. FIG.

  By the way, in the interlocking switching mechanism 36, although the high hydraulic pressure is applied to the hydraulic chamber 72, the connection operation of the first and second switching pins 68 and 69 is hindered for some reason, and the interlocking switching mechanism 36 May remain in the interlock release state. In this case, the first intake valve side rocker arm 33 that drives the intake valve 16 that has a relatively high lift out of the two intake valves 16 and 16 that operate independently of each other has a valve operating system behavior up to a predetermined high rotation range. Therefore, it is necessary to set the spring load of the valve spring 19 to be relatively high corresponding to the weight of the first intake valve side rocker arm 33. Therefore, if the first intake valve side rocker arm 33 is relatively heavy, the spring load of the valve spring 19 must be set correspondingly, and the valve opening power in the interlock release state and the interlock state increases. . However, the hydraulic pressure chamber 72 and the communication path 73 are provided in the third intake valve side rocker arm 35 that drives the intake valve 16 that is relatively lifted out of the two intake valves 16 and 16 that operate independently of each other. Thus, the first intake valve side rocker arm 33 can be reduced in weight by the absence of the hydraulic pressure chamber 72 and the communication passage 73. Therefore, the spring load for biasing the first intake valve side rocker arm 33 is set to be relatively low. This can contribute to reduction of valve opening power.

  Further, in the third intake valve side rocker arm 35 provided with the hydraulic chamber 72 and the communication path 73, the axial length of the rotating body 46> the axial length of the rotating body 45> the axial length of the rotating body 47. Therefore, even if the hydraulic chamber 72 and the communication passage 73 are provided, the width along the axis of the intake valve side rocker arm shaft 37 can be set to be relatively small, whereby the third intake valve side rocker arm 35 of the third intake valve side rocker arm 35 can be set. The increase in weight can be suppressed and the valve opening power can be reduced, and the valve gear can be configured relatively compactly along the axis of the camshaft 26.

  Although the embodiments of the present invention have been described in detail 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. Is possible.

Side view of V-type internal combustion engine FIG. 2 is an enlarged cross-sectional view taken along line 2-2. 3-3 sectional view of FIG. Sectional view along line 4-4 in FIG. Sectional view along line 5-5 in FIG.

Explanation of symbols

16... Intake valve 26... Cam shafts 29, 30, 31 .. Cams 33, 34, 35 .. Intake valve side rocker arm 34 a as an intake valve drive member .. Lost motion mechanism receiving part (lost motion mechanism receiving raised part) 36... Interlocking switching mechanism 37... Intake valve side rocker arm shafts 45 and 46 as swing support shafts ··· Rotating bodies 52, 53, 54 ··· Cylindrical shaft member 62 ········ Lost motion mechanism 68, 69 ··· Switching pin

Claims (1)

Between the camshaft (26) and the intake valve (16), there is an interlocking switching mechanism (36) capable of switching between interlocking and unlocking, and the intake valve (16) is interlocked with the rotation of the camshaft (26). And a plurality of intake valve drive members (33, 34, 35) that are driven in such a manner as to be swingable via a swing support shaft (37),
The interlock switching mechanism (36) includes a switching pin (68, 69) movable between a position where the adjacent intake valve driving members (34, 35; 33, 34) are interlocked and a position where the interlock is released, and a switching pin. And a cylindrical shaft member (54, 53, 52) fixed to the intake valve drive member (35, 34, 33) to guide the movement of (68, 69), and each cylindrical shaft member ( 54, 53, 52) are rotatably supported by cylindrical rotating bodies (47, 46, 45) which are in sliding contact with cams (31, 29, 30) provided on the camshaft (26).
Of the plurality of intake valve drive members (33, 34, 35), the specific intake valve drive member (34) is free from the intake valve (16) when the interlock switching mechanism (36) is in the interlock release state. In the internal combustion engine in which the specific intake valve drive member (34) is elastically biased toward the cam (29) by the lost motion mechanism (62).
The specific cam (29) corresponding to the specific intake valve drive member (34) and the lost motion mechanism (62) face each other with the specific intake valve drive member (34) interposed therebetween. Arranged as
The specific intake valve drive member (34) includes a lost motion mechanism that directly engages the lost motion mechanism (62) around a specific rotating body (46) corresponding to the specific intake valve drive member (34). The receiving part (34a) is integrally projected ,
The width of the lost motion mechanism receiving portion (34a) in the opposing direction where the lost motion mechanism receiving portion (34a) and the lost motion mechanism (62) are directly engaged with each other in the axial direction of the camshaft (26) is mechanism (62) side width smaller set than the cam shaft (26) axial width dimensions rather and the particular rotational body (46) than the,
Furthermore, the width of the specific rotating body (46) is set to be smaller than the width of the specific cam (29) in the axial direction of the camshaft (26) .

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