JP5142804B2 - Valve operating device for internal combustion engine - Google Patents

Description

  The present invention is supported by a camshaft including a valve operating cam, and operates between an operating position where the exhaust valve operating member is operated in the opening direction of the exhaust valve during the compression stroke of the engine and an inoperative position where the exhaust valve operating member is released. Between the decompression cam member that moves the valve, the non-operating position that is supported by the camshaft to release the exhaust valve operating member, and the operating position that can operate the exhaust valve operating member in the opening direction of the exhaust valve during the intake stroke of the engine And an exhaust recirculation cam member that is driven by a crankshaft and a driven timing rotation member that is driven by a crankshaft and rotates integrally with a valve cam. The present invention relates to an improvement in a valve operating apparatus for an internal combustion engine, which is operated and includes a centrifugal mechanism that operates the exhaust gas recirculation cam member at a non-operating position in a low speed operation region of the engine and an operating position in a high speed operation region.

Such a valve operating apparatus for an internal combustion engine is already known as disclosed in Patent Document 1 below.
JP 2005-240793 A

In a conventional valve operating apparatus for an internal combustion engine, a camshaft including an exhaust cam and an intake cam is connected to a driven timing rotating member, and a decompression cam member and an exhaust recirculation cam member supported by the camshaft are driven to rotate at a driven timing. Since it is disposed between the member and the exhaust cam, a sufficient space for disposing the decompression cam member and the exhaust recirculation cam member must be ensured between the driven timing rotating member and the exhaust cam. It was supposed to prevent the valve device from being made compact.

  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 be configured compactly despite the installation of a driven timing rotating member and an exhaust cam. .

In order to achieve the above object, the present invention provides an operating position that is supported by a camshaft provided with a valve operating cam and operates an exhaust valve operating member in an opening direction of the exhaust valve during an engine compression stroke, and an exhaust valve operating valve. A decompression cam member that moves between inoperative positions that release the member, an inoperative position that is supported by the camshaft to release the exhaust valve operating member, and an exhaust valve operating member in the opening direction of the exhaust valve in the intake stroke of the engine An exhaust recirculation cam member that moves between operable operating positions, and a driven timing rotating member that is driven by a crankshaft and rotates integrally with a valve cam, the decompression cam member is operated at an engine starting rotational range. And a centrifugal mechanism for operating the exhaust gas recirculation cam member at a non-operating position in a low-speed operating region of the engine and operating at an operating position in a high-speed operating region. In location, molded integrally driven timing rotational member in one axial end of the valve operating cam, Its valve operating cam, a and the driven timing rotational member surrounds the cam shaft, the side surface opposite to the valve operating cam and a recess that opens to the base circle surface of the valve operating cam, with one axial end of the recess is provided to be closed by the valve operating cam, to accommodate the decompression cam member and the exhaust gas recirculation cam member in the recess, the centrifugal The centrifugal weight of the mechanism is pivotally supported by the driven timing rotating member so as to block a part of the opening surface on the other axial end side of the concave portion, and the concave portion is formed in the valve cam. The first feature is that the valve cam is fitted and fixed to a camshaft formed separately from the camshaft so that the camshaft can be performed without being disturbed by the camshaft .

The intake valve operating member and the exhaust valve operating member respectively correspond to an intake rocker arm 29i and an exhaust rocker arm 29e in an embodiment of the present invention described later, and the driven timing rotating member corresponds to a driven timing pulley 32. In the present invention, the “axial direction” refers to a direction along the axis of the cam shaft.

In addition to the first feature of the present invention, the centrifugal mechanism is pivotally supported by a driven timing rotating member and swings from a contracted position to an intermediate expanded position in response to an increase in centrifugal force, and further swings. The first centrifugal weight, which is prevented from moving, is also pivotally supported by the driven timing rotating member and swings together with the first centrifugal weight from the contracted position to the intermediate extended position in accordance with an increase in centrifugal force. After the weight stops at the intermediate extended position, the second centrifugal weight swings to the extended position independently according to the increase of the centrifugal force, and the second centrifugal weight and the driven timing rotating member When the second centrifugal weight occupies the contracted position when the second centrifugal weight is interlocked with the decompression cam member and the exhaust gas recirculation cam member. , Controlling the decompression cam member to the operating position and exhaust recirculation cam member When controlling to the inoperative position and when the second centrifugal weight occupies the intermediate extended position, both the decompression cam member and the exhaust recirculation cam member are controlled to the inoperative position, and when the second centrifugal weight occupies the extended position The second feature is that the decompression cam member is controlled to the inoperative position and the exhaust gas recirculation cam member is controlled to the operating position.

The present invention, in addition to the second feature, the outer peripheral surface of the valve operating cam, a third feature in that the intake valve operating member and the exhaust valve actuating member is brought into sliding contact out of phase with each other To do.

  According to the first feature of the present invention, the decompression cam member and the exhaust recirculation cam member can be compactly accommodated in the valve operating cam, and the valve operating apparatus can be made compact.

By individually configure the valve operating cam and the cam shaft also the formation of the recess of the valve operating cam can be performed without being disturbed by the cam shaft, it is possible to reduce the cost of the valve gear .

According to the second feature of the present invention, the operation timing of the decompression cam member and the exhaust gas recirculation cam member is determined by setting the contraction position and intermediate expansion position of the first and second centrifugal weights and the expansion position of the second centrifugal weight. Can be achieved easily and reliably.

According to the third feature of the present invention, the intake and exhaust valves can be opened and closed with a single common valve cam, and the valve operating apparatus can be made more compact.

  Embodiments of the present invention will be described below based on preferred embodiments of the present invention shown in the drawings.

1 is a longitudinal sectional front view of an essential part of an internal combustion engine provided with a valve gear according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line 2-2 of FIG. 1, and FIG. 4 is a view taken along arrow 4 in FIG. 3 , FIG. 5 is a view taken along arrow 5 in FIG. 3, FIG. 6 is an exploded perspective view of the main part of the valve operating device, FIG. 7 is a sectional view taken along line 7-7 in FIG. 3 is a sectional view taken along line 8-8 in FIG. 3, FIG. 9 is a sectional view taken along line 9-9 in FIG. 3, FIG. 10 is an action diagram of the valve operating device showing the decompression release and exhaust recirculation stop states, and FIG. FIG. 12 is a diagram showing the operation region of the decompression cam member and the exhaust gas recirculation cam member, and FIG. 13 is a diagram showing the relationship between the rotation angle of the crankshaft and the opening / closing timings of the intake valve and the exhaust valve. It is.

First, in FIG. 1, an engine body 1 of an internal combustion engine E includes a first case half 2a and a second case half 2b that are bolted to each other on a slope that obliquely intersects the axis of the crankshaft 6. The cylinder block 3 extends upward from the second case half 2b, and the cylinder head 4 is formed integrally with the upper end of the cylinder block 3. The crankcase 2 accommodates the crankshaft 6 supported on the left and right side walls thereof, and the crankshaft 6 is connected to the piston 7 fitted in the cylinder bore 3 a of the cylinder block 3 via the connecting rod 8. A known recoil starter 13 capable of cranking the crankshaft 6 is attached to one side of the engine body 1. In FIGS. 1 and 2, the cylinder head 4 includes a combustion chamber 15 connected to the cylinder bore 3 a, The combustion chamber 15 is formed with an intake port 16i and an exhaust port 16e that open the inner end, and an intake valve 17i and an exhaust valve 17e that open and close the intake port 16i and the exhaust port 16e. Intake and exhaust valve springs 30i and 30e for urging them in the valve closing direction are mounted on 17i and 17e, respectively. A valve gear 20 that opens and closes the intake valve 17i and the exhaust valve 17e in cooperation with the valve springs 30i and 30e is disposed from the crankcase 2 to the cylinder head 4. The valve gear 20 will be described in detail later.

  The cylinder head 4 is also screwed with a spark plug 21 that causes the electrode to face the combustion chamber 15, and is further provided with a carburetor 22 and an exhaust muffler 23 connected to the outer ends of the intake port 16 i and the exhaust port 16 e, respectively. An air cleaner 19 is attached to the intake passage entrance 22.

  A fuel tank 24 adjacent to the carburetor 22 and the exhaust muffler 23 is attached to the upper part of the crankcase 2.

  Now, the valve gear 20 will be described.

  As shown in FIGS. 1 to 3, a valve operating chamber 20 a extending upward from the inside of the crankcase 2 and adjacent to one side of the cylinder bore 3 a is formed from the cylinder block 3 to the cylinder head 4. A valve operating device 20 is disposed in the chamber 20a. This valve operating apparatus 20 includes a support shaft 27 disposed in parallel with the crankshaft 6 so as to cross the upper portion of the valve operating chamber 20a, and a hollow cylindrical cam shaft 26 rotatably supported by the support shaft 27. It has. The support shaft 27 is fitted at both ends into a pair of support holes 28, 28 on opposite side walls of the valve operating chamber 20 a, and a presser plate 52 fixed to the outside of the cylinder head 4 with a bolt 51 is provided outside the support shaft 27. The cylinder head 4 is fixed by pressing the end.

As shown in FIGS. 3 to 6, a single valve cam 25 is fitted and fixed to the outer periphery of one end portion of the cam shaft 26 by press fitting or the like. The axial end of the valve operating cam 25, the follower timing-pulleys 32 which surrounds the other end portion of the cam shaft 26 are integrally formed, the driven timing pulley 32 is secured to the crankshaft 6 The drive timing pulley 31 is driven through the timing belt 33 with a reduction ratio of 1/2.

  An intake rocker shaft 34i and an exhaust rocker shaft 34e, which are arranged on both sides of the intake and exhaust valves 17i and 17e and are parallel to the cam shaft 26, are attached to the cylinder head 4, and a valve operating cam is attached to the intake rocker shaft 34i. 25 and an intake rocker arm 29e that connects the intake valve 17i, and an exhaust rocker shaft 29e that supports an exhaust rocker arm 29e that connects the valve cam 25 and the exhaust valve 17e so as to be swingable. These intake and exhaust rocker arms 29i and 29e have mutually different contact phases with the valve cam 25, and receive the lift action of the valve cam 25 at a predetermined timing, so that the intake and exhaust valve springs 30i and 30e As a result, the intake and exhaust valves 17i and 17e are respectively opened and closed.

  The valve operating device 20 is configured as described above, and the head cover 18 that covers the valve operating device 20 from above is joined to the upper end surface of the cylinder head 4.

  As shown in FIGS. 4 to 6, the driven timing pulley 32 includes an arm wall 32 a that extends in the radial direction from one end of the valve cam 25, and a toothed rim 32 b that is formed on the outer periphery of the arm wall 32 a. The first and second centrifugal weights 351 are formed in a substantially U-shape so as to surround the cam shaft 26 by a single pivot shaft 36 fixed to the arm wall 32a and projecting to the outer surface thereof. , 352 are swingably supported. The first and second centrifugal weights 351 and 352 are stacked in a plate shape, and the second centrifugal weight 352 has an oscillating end opposite to the pivot 36 of the first centrifugal weight 351. A contact piece 351a with which the swing end can come into contact is formed.

  Thus, the first centrifugal weight 351 has the contact piece 351a at the distance collar from the contracted position A (see FIG. 5) where the U-shaped bent portion contacts the outer peripheral surface of the distance collar 49 on the camshaft 26. It swings around the pivot 36 to an intermediate expansion position M (see FIG. 10) that contacts the outer peripheral surface of 49, and cannot swing beyond this intermediate expansion position M. Further, the second centrifugal weight 352 can swing around the pivot 36 from the contracted position A through the intermediate operating position M to the expanded position B. The contracted position A of the second centrifugal weight 352 (FIG. 5) is defined by bringing the swinging end of the second centrifugal weight 352 into contact with the contact piece 351a when the first centrifugal weight 351 is in the contracted position A. The intermediate extended position M (see FIG. 10) is defined by bringing the swinging end of the second centrifugal weight 352 into contact with the contact piece 351a when the first centrifugal weight 351 is in the intermediate extended position M. The expansion position B (see FIG. 11) of the second centrifugal weight 352 is such that when the first centrifugal weight 351 is constrained to the intermediate expansion position M, the second centrifugal weight 352 is separated from the contact piece 351a by a predetermined distance. A stop formed on the side edge of the first centrifugal weight 351 opposite to the contact piece 351a. It is defined by contact at one 351b. A return spring 43 that biases the second centrifugal weight 352 toward the contracted position A with a predetermined set load is provided between the locking claw 40 of the second centrifugal weight 352 and the locking pin 41 of the arm wall 32a. It is stretched between. The first centrifugal weight 351, the second centrifugal weight 352, and the return spring 43 constitute a centrifugal mechanism 46 that operates a drive ring 45 described later.

3, as shown in FIGS. 7-9, the valve operating cam 25, the outer surface of the cam shaft 26 surrounds and driven timing-pulleys 32 (i.e. opposite the side with the valve operating cam 25) A recess 39 that opens to the base circular surface 25a of the valve cam 25 is provided such that one end in the axial direction of the recess 39 (that is, the valve cam 25 side) is closed by the valve cam 25. The exhaust recirculation cam member 48, the decompression cam member 47, the drive ring 45, and the distance collar 49 are sequentially fitted to the cam shaft 26 from the valve operating cam 25 side. Therefore, the exhaust gas recirculation cam member 48, the decompression cam member 47, and the drive ring 45 are all accommodated in the recess 39 of the valve cam 25.

  3 and 5 to 9, the drive ring 45 is rotatably fitted to the outer peripheral surface of the camshaft 26, and the drive ring 45 protrudes from the outer peripheral surface so as to protrude first and second. A connection protrusion 45a extending toward the centrifugal weights 351 and 352 is integrally formed, and the connection protrusion 45a is engaged with a connection groove 352a provided on the inner periphery of the swing end of the second centrifugal weight 352. Thus, when the second centrifugal weight 352 swings in the radial direction, the drive ring 45 is rotated via the connection protrusion 45a. Further, the drive ring 45 has an axial holding groove 45b on its inner peripheral surface, and the holding groove 45b extends between the driven timing pulley 32 and the valve cam 26e in the axial direction of the cam shaft 26. An extending roller 44 is held. The roller 44 can roll on the outer peripheral surface of the cam shaft 26 by relative rotation of the drive ring 45 with the cam shaft 26.

  7 to 11, the decompression cam member 47 and the exhaust recirculation cam member 48 slide along a pair of guide surfaces 55, 55 formed on both side surfaces of the cam shaft 26 along the diameter line of the cam shaft 26. It is fitted so that it can move. Thereby, the decompression cam member 47 can slide between the operation position C (FIG. 8) and the non-operation position D (FIG. 10) along the guide surfaces 55, 55. The operation position C and the non-operation position D are The inner end surfaces 56 a and 56 b of the decompression cam member 47 in the direction orthogonal to the guide surfaces 55 and 55 are defined by contacting the outer peripheral surface of the cam shaft 26. Further, the exhaust gas recirculation cam member 48 can slide between the non-operation position F (FIG. 7) and the operation position G (FIG. 11) along the guide surfaces 55, 55. The inner end surfaces 57 a and 57 b of the exhaust gas recirculation cam member 48 in the direction orthogonal to the guide surfaces 55 and 55 are defined by contacting the outer peripheral surface of the cam shaft 26.

  The decompression cam member 47 and the exhaust gas recirculation cam member 48 integrally have convex cams 47a and 48a that are much lower than the nose portion of the valve operating cam 25 on their outer peripheral surfaces, and these convex cams 47a and 48a are integrated with each other. In each of the operating positions C and G, the valve cam 25 protrudes outward from the base circular surface 25a, and in the non-operating positions D and F, it retreats into the base circular surface 25a. The convex cam 47a of the decompression cam member 47 is arranged so as to push up the exhaust rocker arm 29e during the compression stroke of the engine when it occupies the operating position C. The convex cam 48a of the exhaust recirculation cam member 48 has an operating position G. It is arranged to push up the exhaust rocker arm 29e during the intake stroke of the engine when occupied.

  As shown in FIG. 8, a concave cam 58 that cooperates with the roller 44 is formed at the center of the inner end surface 56b of the decompression cam member 47 on the convex cam 47a side. The concave cam 58 has an inclined surface 58a forcing the decompression cam member 47 to the operating position C by being pressed by the roller 44 when the second centrifugal weight 352 is held at the contracted position A by the urging force of the return spring 43. When the second centrifugal weight 352 is swung to the intermediate extension position M, an arc-shaped bottom surface 58b that allows the decompression cam member 47 to move to the inoperative position D while avoiding the interference of the roller 44 is formed. The decompression cam member 47 has its center of gravity offset from the center of the decompression cam member 47 to the opposite side of the concave cam 58, and when the roller 44 comes to a position facing the arcuate bottom surface 58b, the decompression cam member 47 acts on the center of gravity. The inactive position D is shifted by the centrifugal force.

  As shown in FIGS. 7 and 11, on the other hand, a concave cam 59 that cooperates with the roller 44 is formed at the center of the inner end surface 57b of the exhaust recirculation cam member 48 on the convex cam 48a side. While the second centrifugal weight 352 rotates from the contracted position A to the intermediate expanded position M, the concave cam 59 avoids interference with the roller 44 and shifts the exhaust gas recirculation cam member 48 to the inoperative position F. When the second centrifugal weight 352 is swung to the extended position B, the roller 59 is pressed by the roller 44 to force the exhaust gas recirculation cam member 48 to the operating position G. Yes. The exhaust gas recirculation cam member 48 has its center of gravity offset from the center of the exhaust gas recirculation cam member 48 to the opposite side of the concave cam 59, and the roller 44 is located at a position facing the arcuate bottom surface 59a. Is moved to the inoperative position G by the centrifugal force acting on the center of gravity.

  Next, the operation of this embodiment will be described.

  When the crankshaft 6 rotates, the drive timing pulley 31 drives the driven timing pulley 32 via the timing belt 33, so that the valve cam 25 integrated with the driven timing pulley 32 is also driven to rotate. In the intake stroke, the nose portion of the valve cam 25 swings the intake rocker arm 29i and pushes the intake valve 17i against the urging force of the intake valve spring 30i. In the exhaust stroke, the nose portion of the valve cam 25 swings the exhaust rocker arm 29e and pushes the exhaust valve 17e open. FIG. 13 shows the opening / closing timing of the intake valve 17i and the exhaust valve 17e.

  In FIG. 12, in the engine starting rotational speed range a between the engine speed Ne of 0 and a predetermined engine speed Ne1 lower than the idling engine speed, as shown in FIGS. The second centrifugal weights 351 and 352 are both held at the contracted position A by the set load of the return spring 43. At this time, the drive ring 45 connected to the second centrifugal weight 352 via the connection protrusion 45a presses the roller 44 against the inclined surface 58a of the concave cam 58 of the decompression cam member 47, so that the decompression cam member 47 has its convex cam. 47a is held at the operating position C where the valve cam 25 protrudes outward from the base circular surface 25a.

  Therefore, when the recoil starter 13 is operated to start the internal combustion engine E, the crankshaft 6 is cranked from the starter 13 via the starting cylinder shaft 12, and at the same time, the valve operating cam via the timing belt 33 or the like. 25 is driven to rotate, as described above, in the compression stroke of the piston 7, the convex cam 47a of the decompression cam member 47 slightly pushes up the exhaust rocker arm 29e and slightly opens the exhaust valve 17e. The timing at this time is shown in FIG. As a result, a part of the compressed gas in the cylinder bore 3a is discharged to the exhaust port 16e, and the increase in the compression pressure is suppressed, so that the operation load of the starter 13 is reduced and the crankshaft 6 is relatively lightened. The engine can be cranked vigorously and thus the engine can be started easily.

  When the engine is started and the engine rotational speed Ne rises so as to escape from the starting rotational range a, as shown in FIG. 10, around the pivot 36 by the total centrifugal force of the first and second centrifugal weights 351 and 352. The moment overcomes the moment around the pivot 36 of the first centrifugal weight 351 due to the set load of the return spring 43, so that the first and second centrifugal weights 351 and 352 are integrated radially outward from the contracted position A. And the contact piece 351a of the first centrifugal weight 351 comes into contact with the outer peripheral surface of the distance collar 49 on the camshaft 26, so that the first and second centrifugal weights 351 and 352 are both in the intermediate extended position. M is reached and only the first centrifugal weight 351 is prevented from further expansion. During this time, the swing of the second centrifugal weight 352 from the contracted position A to the intermediate extended position M is transmitted to the connecting protrusion 45a, and the drive ring 45 is rotated counterclockwise in FIG. The concave cam 58 is moved to a position facing the bottom surface 58b. Therefore, the decompression cam member 47 moves to the inoperative position D by the action of centrifugal force without being obstructed by the roller 44, and retracts the convex cam 47a to the inside of the base circular surface 25a of the valve cam 25.

  During this time, in the exhaust gas recirculation cam member 48, as shown in FIG. 7, the bottom surface 59a of the concave cam 59 faces the roller 44 of the drive ring 45, so that the exhaust gas recirculation cam member 48 is also restrained by the roller 44. Without being moved to the inoperative position F by the centrifugal force, the convex cam 48a is retracted to the inside of the base circular surface 25a of the valve cam 25.

  As described above, the exhaust valve 17e is normally controlled to open and close depending on only the original shape of the valve cam 25.

  By the way, when the first centrifugal weight 351 reaches the intermediate expansion position M, further expansion oscillation is blocked by the camshaft 26. Therefore, after the engine speed Ne rises to Ne1 or more, the second centrifugal weight is increased. While the weight 352 is not separated from the contact piece 351a of the first centrifugal weight 351, the load acting on the return spring 43 is constant. Therefore, in the engine speed range Ne1 to Ne2 in which the return spring 43 cannot be deformed only by the centrifugal force of the second centrifugal weight 352, that is, in the low speed operation range b including idling, the second centrifugal weight 352 is in the intermediate extension position M. Will be held.

  When the engine speed Ne becomes Ne2 or more, that is, when the engine speed Ne enters the high speed operation range c, the centrifugal force of the second centrifugal weight 352 increases sufficiently, and the moment around the pivot 36 of the second centrifugal weight 352 due to the centrifugal force. Is larger than the moment of the second centrifugal weight 352 due to the load of the return spring 43, so that the second centrifugal weight 352 reaches the expanded position B as shown in FIG. By rotating counterclockwise, the roller 44 presses the inclined surface 59b of the concave cam 59 of the exhaust recirculation cam member 48 and moves the exhaust recirculation cam member 48 to the operating position G against the centrifugal force. The reflux cam member 48 has a convex cam 48 a protruding from the base circular surface 25 a of the valve operating cam 25. Therefore, as described above, in the intake stroke of the piston 7, the convex cam 48a of the exhaust recirculation cam member 48 slightly pushes up the exhaust rocker arm 29e, thereby slightly opening the exhaust valve 17e. As a result, the exhaust gas remaining in the exhaust port 16e is drawn into the combustion chamber 15, that is, the exhaust gas is recirculated. This exhaust gas suppresses an excessive increase in the combustion temperature during combustion of the air-fuel mixture in the subsequent expansion stroke, lowers the NOx concentration in the exhaust gas, and contributes to the reduction of the HC concentration and hence the improvement of fuel efficiency. To do.

  As described above, the common drive ring 45 is operated by the centrifugal mechanism 46 including the first and second centrifugal weights 351 and 352 and the return spring 43, and the decompression cam member 47 and the exhaust recirculation cam member 48 are sequentially operated. Therefore, the structure of the valve gear 20 having a decompression function and an exhaust gas recirculation function having desired characteristics without mutual interference can be simplified and made compact.

  In addition, the centrifugal mechanism 46 is attached to the outer surface of the driven timing pulley 32, and the decompression cam member 47 and the exhaust gas recirculation cam member 48 are accommodated in the recess 39 of the valve cam 25 formed integrally with the driven timing pulley 32. At the same time, since the decompression cam member 47 and the exhaust gas recirculation cam member 48 can be accommodated in the valve operating cam 25 in a compact manner, the valve operating device 20 can be made more compact.

  In the centrifugal mechanism 46, the decompression cam member 47 and the exhaust recirculation cam are set by setting the contraction position A and the intermediate expansion position M of the first and second centrifugal weights 351 and 352 and the expansion position B of the second centrifugal weight 352. The operation timing of the member 48 can be easily and reliably achieved.

  Further, the intake valve arm 29i and the exhaust rocker arm 29e that open and close the intake valve 17i and the exhaust valve 17e, respectively, are brought into sliding contact with the outer peripheral surface of the valve cam 25 with the phases shifted from each other. Thus, the intake and exhaust valves 17i and 17e can be opened and closed, and the valve operating device 20 can be made more compact.

The present invention is not limited to the above embodiments, and various design changes can be made without departing from the scope of the invention. For example, abolished the stopper 3 51b for restricting the extended position B of the second centrifugal weight 3 52, the roller 44 by abutting the bottom surface 58b side end wall of the recessed cam 58 of the decompression cam member 47, the second it is also possible to regulate the expanded position B of the centrifugal weight 3 52.

  When the present invention is applied to a valve operating apparatus in which the camshaft 26 is provided with an intake cam and an exhaust cam, if the decompression cam member 47 and the exhaust recirculation cam member 48 are accommodated in the cam close to the driven timing pulley 32. Good. Further, the timing transmission device including the drive timing pulley 31, the driven timing pulley 32, and the timing belt 33 can be configured as a gear type. In this case, the driven timing rotating member of the present invention is constituted by a driven timing gear.

BRIEF DESCRIPTION OF THE DRAWINGS The principal part longitudinal cross-sectional front view of the internal combustion engine provided with the valve gear which concerns on the Example of this invention. FIG. 2 is a sectional view taken along line 2-2 in FIG. 1. 3 is an enlarged view of part 3 of FIG. 4 arrow view of FIG. FIG. 5 is a view taken in the direction of arrow 5 in FIG. 3. The principal part disassembled perspective view of the said valve operating apparatus. FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 3. FIG. 8 is a cross-sectional view taken along line 8-8 in FIG. 3. FIG. 9 is a sectional view taken along line 9-9 in FIG. 3. The action figure of the valve operating apparatus which shows decompression cancellation | release and an exhaust gas recirculation stop state. The action figure of the valve operating apparatus which shows an exhaust gas recirculation | reflux state. The diagram which shows the action | operation area | region of a decompression cam member and an exhaust recirculation cam member. The diagram which shows the relationship between the rotation angle of a crankshaft, and the opening / closing timing of an intake valve and an exhaust valve.

E ········· Internal combustion engine A ····················· Contraction position M of the first and second centrifugal weights ····· Intermediate extension position B of the first and second centrifugal weights ... Expansion position C of second centrifugal weight ... Operation position D of decompression cam member ... Inoperative position F of decompression cam member ... Position G: Exhaust recirculation cam member operating position 6: Crankshaft 17e ... Exhaust valve 20: Valve operating device 25: Valve cam 26 ... Camshaft 29i ... Intake valve actuating member (intake rocker arm)
29e ... Exhaust valve operating member (exhaust rocker arm)
32... Rotating member (driven timing pulley)
351 ··· First centrifugal weight 352 ··· Second centrifugal weight 39 ··· concave portion 43 · · · return spring 46 · · · centrifugal mechanism 47 ··· decompression cam Member 48 ... Exhaust gas recirculation cam member

Claims (3)

An operating position (C) supported by a camshaft (26) having a valve operating cam (25) and operating the exhaust valve operating member (29e) in the opening direction of the exhaust valve (17e) in the compression stroke of the engine; A decompression cam member (47) that moves between an inoperative position (D) that releases the valve valve member (29e), and an inoperative position that is supported by the cam shaft (26) and releases the exhaust valve operating member (29e). (F), an exhaust recirculation cam member (48) that moves between operating positions (G) that can operate the exhaust valve operating member (29e) in the opening direction of the exhaust valve (17e) in the intake stroke of the engine, and a crankshaft (6) is attached to a driven timing rotating member (32) which is driven by (6) and rotates integrally with the valve cam (25), and the decompression cam member (47) is moved to the operating position (C) in the engine starting rotation region (a). ) To the non-operating position (D) after starting The centrifugal mechanism (46) moves and moves the exhaust recirculation cam member (48) to the non-operation position (F) in the low speed operation region (b) of the engine and to the operation position (G) in the high speed operation region (c). A valve operating apparatus for an internal combustion engine,
Shaped driven timing rotating member (32) integral with one axial end of the valve operating cam (25), in its valve operating cam (25), surrounds the cam shaft (26) and the driven timing rotating member (32 ) Of the concave portion (39) that opens to the side surface opposite to the valve cam (25) and the base circular surface (25a) of the valve cam (25), one end in the axial direction of the concave portion (39) moves. Provided to be closed by the valve cam (25) ,
The recess (39) accommodates the decompression cam member (47) and the exhaust gas recirculation cam member (48), and the centrifugal weights (351, 352) of the centrifugal mechanism (46) serve as the shaft of the recess (39). Pivotally supported by the driven timing rotating member (32) so as to block a part of the opening surface on the other end side in the direction,
The camshaft (26) is formed separately from the valve cam (25) so that the concave portion (39) can be formed in the valve cam (25) without being obstructed by the camshaft (26). ) to fitted, characterized in that the fixed valve operating equipment of the internal combustion engine. The valve gear for an internal combustion engine according to claim 1,
The centrifugal mechanism (46) is pivotally supported by the driven timing rotating member (32) and swings from the contracted position (A) to the intermediate extended position (M) in response to an increase in centrifugal force. The first centrifugal weight (351) that is prevented from being moved and the first centrifugal weight (351), which is also supported by the driven timing rotating member (32), is moved from the contracted position (A) to the intermediate expanded position (M) in response to an increase in centrifugal force. After swinging with the centrifugal weight (351) and stopping at the intermediate extended position (M), the first centrifugal weight (351) swings independently to the extended position (B) as the centrifugal force increases. The second centrifugal weight (352) is biased toward the contracted position (A) between the second centrifugal weight (352) and the second centrifugal weight (352) and the driven timing rotating member (32). The second centrifugal weight (352) is composed of a decompression cam member (47) and an exhaust. When the second centrifugal weight (352) occupies the contracted position (A) in conjunction with the flow cam member (48), the decompression cam member (47) is controlled to the operating position (D) and the exhaust recirculation cam member When (48) is controlled to the inoperative position (F) and the second centrifugal weight (352) occupies the intermediate expansion position (M), the decompression cam member (47) and the exhaust recirculation cam member (48) are both When the non-operating position (D, F) is controlled and the second centrifugal weight (352) occupies the expanded position (B), the decompression cam member (47) is controlled to the non-operating position (D) and the exhaust gas recirculates. A valve operating apparatus for an internal combustion engine, wherein the cam member (48) is controlled to an operating position (G). The valve operating apparatus for an internal combustion engine according to claim 2 ,
A valve operating apparatus for an internal combustion engine, characterized in that an intake valve operating member (29i) and an exhaust valve operating member (29e) are slidably brought into sliding contact with each other on the outer peripheral surface of the valve cam (25). .

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