JP2012007596A - Variable valve system of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve switch actuation response between a first cam and second cam in a variable valve system.SOLUTION: A valve camshaft 16 is composed of a first camshaft 16a equipped with low-lift second cams 18i and 18e and connected with a timing transmission device 8, and a second camshaft 16b equipped with high-lift first cams 17i and 17e, which penetrates the first camshaft 16a on the same axis and disposed to enable relative rotation and to make an axial movement impossible. An engaging part 31 is formed in the first camshaft 16a. Meanwhile, the second camshaft 16b is engaged with a clutch member 30, and then with an engaging part 31. Spline connection is made to slide between a coupling position A, which connects between the first and second camshafts, 16a and 16b with a predetermined phase relation, and a uncoupling position B, which secedes from the engaging part 31 and disconnect between the first and second camshafts, 16a and 16b. After that, A clutch shifting means 32, which is freely supported by this clutch member 30 for axial direction sliding at the second camshaft 16b, is connected.

Description

  In the present invention, the valve camshaft is provided with a first cam and a second cam having a lower lift than the first cam, and the operation of one of the first cam and the second cam is alternately selected, The present invention relates to an improvement in a variable valve operating apparatus for an internal combustion engine that opens and closes an engine valve by operating a selected cam.

  As disclosed in Japanese Patent Application Laid-Open No. 2004-228688, the present applicant has provided a first cam as a variable valve device for an internal combustion engine so as to be relatively rotatable on a valve camshaft, while providing a second cam as a valve operating valve. A mode switching device that is fixed to the camshaft and that can be switched alternately between an operation mode for connecting the first cam to the valve operating camshaft and a non-operation mode for releasing the connection is connected to the first cam, The mode switching device includes an actuator, a control rod that is slidably inserted into a rod guide hole in the center of the valve camshaft, and is shifted between an operating position and an inoperative position by the actuator, A connecting portion provided on the cam and projecting on the outer peripheral surface of the control rod, and at the operating position of the control rod, engages with the connecting portion to connect the valve operating camshaft and the first cam; In the non-operating position of the Those composed of a connecting pin to release the first cam from the connection between the valve operating cam shaft has already proposed.

JP 2010-65565 A

  However, in the above proposal, the connecting pin that moves between the operating position and the non-operating position engages with the connecting portion at the operating position and participates in the transmission between the valve camshaft and the first cam. When moving from the position to the non-operating position, the transmission torque acts on the sliding portion of the connecting pin and the sliding friction of the connecting pin increases, so that the connecting pin does not move smoothly. It was found that the response of switching operation between cams was low.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a variable valve operating apparatus for an internal combustion engine that has a good response of switching operation between the first cam and the second cam.

  In order to achieve the above object, according to the present invention, a valve camshaft is provided with a first cam and a second cam having a lower lift than the first cam, and one of the first cam and the second cam. In a variable valve operating apparatus for an internal combustion engine in which the operation is alternately selected and the engine valve is opened and closed by the operation of the selected cam, the valve operating camshaft is provided with the second cam and the timing transmission A first camshaft integrally connected to the driven wheel; and the first camshaft passing coaxially through the first camshaft and being relatively rotatable with respect to the first camshaft and not axially movable; A first camshaft, and an engaging portion formed on the first camshaft, while a clutch member is engaged with the second camshaft, and the first and second camshafts engage with the engaging portion. A connecting position for connecting the two camshafts in a predetermined phase relationship, and the first and second camshafts separated from the engaging portion. The second camshaft is spline-fitted so as to be able to slide between the unconnected positions for releasing the connection between the second camshafts, and the clutch member is shifted to the second position in order to shift it between the connected position and the unconnected position. A first feature is that clutch shift means supported to be slidable in the axial direction is connected to the cam shaft.

  The engine valve corresponds to an intake valve 12i and an exhaust valve 12e in an embodiment of the present invention to be described later, the first cam is the first intake and exhaust cams 17i and 17e, and the second cam is the second intake valve. And the exhaust cams 18i and 18e, respectively, and the driven wheel corresponds to the driven gear 8b.

  According to the present invention, in addition to the first feature, the clutch shift means includes a shift rod slidably supported in a guide hole formed in a central portion of the second camshaft, and the guide hole. The second cam shaft includes a connecting pin that connects the shift rod to the clutch member through a long hole that communicates with the outer peripheral surface of the second camshaft, and an actuator that can operate the shift rod is connected to the shift rod. It is characterized by.

  In addition to the first feature of the present invention, the engagement portion is formed by an engagement recess extending along the rotation direction of the first cam shaft, and the clutch member is connected to the connection position and the non-connection. A dog that enters and leaves the engaging recess according to the movement to the position is provided, the rotational width of the engaging recess is set sufficiently larger than the rotational width of the dog, and the engagement of the dog When entering the recess, the dog contacts the inner end surface of the engagement recess opposite to the rotation direction so that the first and second camshafts are connected in a predetermined phase relationship. A one-way clutch is interposed between the second cam shaft and the one-way clutch. The one-way clutch allows the first cam shaft to rotate in advance with respect to the second cam shaft. Configured to prevent pre-rotation relative to the first camshaft The third feature and.

  According to the first feature of the present invention, the clutch member is slidably fitted to the second cam shaft in a slidable manner, and is only involved in torque transmission from the first cam shaft to the second cam shaft at the connected position. The clutch shift means is supported by the second cam shaft so as to be slidable in the axial direction, and is involved in moving the clutch member between the connected position and the non-connected position, and is not involved in torque transmission. The sliding frictional resistance of the means is reduced, and the switching response of the clutch member, that is, the switching response of the operation between the first cam and the second cam can be improved. Further, the clutch member and the clutch shift means share the roles as described above, so that each load can be reduced and durability can be improved.

  According to the second feature of the present invention, the clutch shift means can be compactly accommodated in the second camshaft, and can be operated smoothly by this actuator.

  According to the third feature of the present invention, the rotational width of the engaging recess is set to be sufficiently larger than the rotational width of the dog, so that the clutch member is the clutch shift means during the rotation of the first camshaft. Thus, the engagement recess can reliably receive the dog when pressed to the connecting position side. In addition, since the one-way clutch is interposed between the first and second cam shafts, the one-way clutch allows the first rotation of the first cam shaft on the driving side relative to the second cam shaft, so The inner end surface opposite to the rotation direction can be brought into contact with the dog. Further, at the time of the contact, even if the second camshaft on the driven side tries to make a preceding rotation with respect to the first camshaft on the driving side due to the contact impact, the one-way clutch prevents the previous rotation of the second camshaft. The contact state between the inner end face of the engaging recess and the dog, that is, the connection state under a predetermined phase between the first and second cam shafts can be ensured.

1 is a longitudinal side view of a premixed compression self-ignition internal combustion engine equipped with a variable valve device according to the present invention. The principal part perspective view of the variable valve apparatus in FIG. FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 2 (a state where the clutch member is in the coupling position). FIG. 3 is a cross-sectional view taken along line 3-3 in 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. 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. 3 is a lift characteristic diagram of various cams in the variable valve operating apparatus.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  First, in FIG. 1, an engine main body 1 of a premixed compression self-ignition internal combustion engine (hereinafter simply referred to as an internal combustion engine) E is a cylinder that is connected to an upper portion of a crankcase 2 and the crankcase 2 and has a cylinder bore 3a. A block 3 and a cylinder head 4 having a combustion chamber 4a joined to the upper end of the cylinder block 3 and connected to the cylinder bore 3a are provided, and are connected to a crankshaft 5 supported by the crankcase 2 via a connecting rod 6. The piston 7 is fitted into the cylinder bore 3a.

  The cylinder head 4 is formed with an intake port 10i and an exhaust port 10e that open to the combustion chamber 4a, respectively, and an intake valve 12i and an exhaust valve 12e that open and close them. A spark plug 14 is screwed onto the cylinder head 4 so that the electrode faces the combustion chamber 4a. The compression ratio of the internal combustion engine E is set larger than that of a normal electric ignition type internal combustion engine.

  Further, the cylinder head 4 is connected to a throttle body (not shown) having a gas fuel nozzle connected to the intake port 10i so as to supply a premixed gas fuel and air to the internal combustion engine E. It has become.

  The intake valve 12i and the exhaust valve 12e are connected to a variable valve operating device 15 that opens and closes the valve and controls valve opening lift and valve opening timing of these valves. The variable valve operating device 15 will be described with reference to FIGS.

  As shown in FIGS. 1 to 3, a valve camshaft 16 driven from the crankshaft 5 through a timing transmission device 8 (FIG. 1) with a reduction ratio of ½ is connected to the crankcase 2 with a pair of left and right bearings. It is rotatably supported via 21 and 22 (FIG. 3). The timing transmission device 8 includes a drive gear 8a and a driven gear 8b fixed to the crankshaft 5 and the valve drive camshaft 16, respectively. The direction of rotation of the driven gear 8b is indicated by an arrow R.

  The valve camshaft 16 has a first camshaft 16a integrally connected to the driven gear 8b at one end thereof, and can pass through the first camshaft 16a coaxially and be relatively rotatable with respect to the first camshaft 16a. The second cam shaft 16b is fitted so as not to move in the axial direction, and both ends of the second cam shaft 16b are supported by the pair of bearings 21 and 22. The first intake cam 17i and the first exhaust cam 17e are adjacent to each other on the second cam shaft 16b, and the second intake cam and the second exhaust cam 18e are adjacent to each other on the first cam shaft 16a. It is formed. The first and second exhaust cams 17e and 18e are disposed adjacent to each other, and the first and second intake cams 17i and 18i are disposed on both sides thereof. The second intake cam 18i has a lower lift than the first intake cam 17i, and the second exhaust cam 18e has a lower lift than the first exhaust cam 17e.

  A fan-shaped engaging recess 31 is formed on the outer surface of the driven gear 8b along the outer periphery of the second cam shaft 16b. The clutch member 30 having a dog 30a that can enter and leave the engagement recess 31 is spline-fitted to the second cam shaft 16b. The clutch member 30 has a second cam between a connection position A (FIG. 3) where the dog 30a enters the engagement recess 31 and a non-connection position B (FIG. 4) where the dog 30a is disengaged from the engagement recess 31. Since it can move on the shaft 16b, the rotation width S1 of the engagement recess 31 is set to be several times larger than the rotation direction width S2 of the dog 30a so that the dog 30a can easily enter the engagement recess 31. The At the coupling position A of the clutch member 30, the dog 30a abuts against the inner end surface 31a of the engaging recess 31 opposite to the rotational direction R of the driven gear 8b, thereby connecting the first and second cam shafts 16a, 1b. Are connected in a predetermined phase relationship. A one-way clutch 40 is interposed between the first and second cam shafts 16a and 1b. The one-way clutch 40 allows the first cam shaft 16a to advance in advance with respect to the second cam shaft 16b along the rotational direction R of the driven gear 8b, but the second cam shaft 16b is allowed to rotate in the first cam. Pre-rotation with respect to the shaft 16a is prevented.

  The clutch member 30 is connected to a clutch shift means 32 that operates between the coupling position A and the non-coupling position B. This will be described with reference to FIGS.

  At the center of the first cam shaft 16a, there is provided a guide hole 33 having one end opened on the end surface on the driven gear 8b side and the other end dead end. The guide hole 33 is formed on the outer peripheral surface of the second cam shaft 16b. A long hole 34 extending in the axial direction of the second cam shaft 16 b is provided so as to communicate with the second cam shaft 16 b, and the clutch shift means 32 penetrates the shift rod 35 slidably supported by the guide hole 33 and the long hole 34. And a connecting pin 36 that connects the shift rod 35 to the clutch member 30. Thus, the clutch shift means 32 is housed compactly in the second cam shaft 16b.

  An output rod 39a of an electric, electromagnetic or hydraulic actuator 39 supported by the engine body 1 is connected to the outer end of the shift rod 35 so as to be relatively rotatable, and the dead end portion of the guide hole 33 and the shift rod 35 are connected to each other. In the meantime, a return spring 37 that biases the shift rod 35 toward the actuator 39 is contracted. Thus, when the actuator 39 is operated, the output rod 39a presses the shift rod 35 and moves the clutch member 30 to the coupling position A against the urging force of the return spring 37. 37 is configured to return the clutch member 30 to the non-connection position B by the biasing force.

  An electronic control unit 42 that controls the operation of the actuator 39 is connected. When the electronic control unit 42 receives the output signal of the temperature sensor 43 that detects the engine temperature, for example, the water temperature of the water jacket of the engine body 1, and determines that the engine temperature is in a low temperature range below a predetermined value, 39 and the spark plug 14 are both controlled to be in an operating state, and when it is determined that the temperature of the internal combustion engine E is in a high temperature range equal to or higher than a predetermined value, both the actuator 39 and the spark plug 14 are controlled to be in an inoperative state. ing.

  FIG. 9 shows the first and second intake cams 17i and 18i and the first and second exhaust cams 17e and 18e when the first and second cam shafts 16a and 1b are connected to each other under a predetermined phase. The lift characteristic diagram, in other words, the valve opening characteristics of the intake valve 12i and the exhaust valve 12e are shown. As is clear from the above, the profile of the second intake cam 18i is within the range of the profile of the first intake cam 17i, and the first intake cam 17i has a larger nose portion than the second intake cam 18i. Further, the apex of the nose portion of the second intake cam 18i is advanced by a constant angle θi above the apex of the nose portion of the first intake cam 17i. In FIG. 9, S <b> 1 corresponds to the rotational width S <b> 1 of the engagement recess 31, and indicates a region where the dog 30 a is allowed to enter the engagement recess 31.

  The profile of the second exhaust cam 18e is within the range of the profile of the first exhaust cam 17e, and the first exhaust cam 17e has a larger nose portion than the second exhaust cam 18e. The apex of the nose portion of the cam 18e is retarded by a constant angle θe on the crank angle from the apex of the nose portion of the first exhaust cam 17e.

  Further, when the first intake cam 17i and the first exhaust cam 17e dominate the opening and closing of the intake valve 12i and the exhaust valve 12e, the opening timing of the intake valve 12i and the closing timing of the exhaust valve 12e fluctuate, and both valves 12i , 12e are overlapped so that the valve opening period overlaps by α for a certain period. That is, the intake valve 12i starts to open before top dead center, and the exhaust valve 12e finishes closing after top dead center.

  Further, when the second intake cam 18i and the second exhaust cam 18e control the opening and closing of the intake valve 12i and the exhaust valve 12e, a negative overlap in which the opening timing of the intake valve 12i and the closing timing of the exhaust valve 12e are separated by β for a certain period. Has come to occur. That is, the intake valve 12i starts to open after top dead center, and the exhaust valve 12e finishes closing before top dead center.

  3 and 6 to 8, a support shaft 20 is rotatably supported by the engine body 1 in parallel with the valve operating cam shaft 16, and an intake lifter 25 i and an exhaust lifter 25 e are supported by the support shaft 20. The exhaust lifter 25e is swingably supported by the support shaft 20, and is configured so that the slipper portion is in sliding contact with both outer peripheral surfaces of the first exhaust cam 17e and the second exhaust cam 18e. , A first lifter 25i1 having a slipper portion slidably contacting the outer peripheral surface of the first intake cam 17i, and a second lifter 25i2 having a slipper portion slidably contacting the outer peripheral surface of the second intake cam 18i. And the flat surface 23 for rotation prevention which mutually contacts the fitting part of the 2nd lifter 25i1, 25i2 and the support shaft 20 is formed. Accordingly, the first and second lifters 25i1 and 25i2 are integrally connected via the support shaft 20 and swing simultaneously.

  On the other hand, on the cylinder head 4, intake and exhaust rocker arms 27i and 27e are pivotally supported in such a manner that their one ends are brought into contact with the upper ends of the intake and exhaust valves 12i and 12e. An intake lifter 25i (one of the first and second lifters 25i1 and 25i2) is connected to the other end of the intake rocker arm 27i via an intake pushrod 28i, and the other end of the exhaust rocker arm 27e is connected to the other end of the exhaust rocker arm 27e. The exhaust lifter 25e is connected to the exhaust push rod 28e.

  The operation of this embodiment will be described.

  When the operation of the internal combustion engine E is stopped, the clutch member 30 is held at the non-coupled position B (FIG. 4) where the dog 30a is disengaged from the engaging recess 31 by the urging force of the return spring 37 due to the non-actuated state of the actuator 39. The

  Now, in order to start the internal combustion engine E, the crankshaft 5 is cranked by the operation of a starter motor (not shown). At this time, since the engine temperature is in a predetermined low temperature range, the electronic control unit 42 sets the actuator 39 in an operating state and also sets the spark plug 14 in an operable state. By the operation of the actuator 39, the output rod 49a shifts the clutch member 30 to the connection position A side against the urging force of the return spring 37 as shown in FIG.

  As the crankshaft 5 is cranked, the driven gear 8b and the first camshaft 16a connected thereto rotate in a predetermined direction R, while the second camshaft 16b and the clutch member 30 spline-fitted thereto have each part. The clutch member 30 is moved to the coupling position A by the pressing force of the actuator 39 as soon as the engaging recess 31 of the driven gear 8b comes to the receiving position of the dog 30a of the clutch member 30. The dog 30a enters the engaging recess 31. Then, the inner end surface 31a of the engaging recess 31 that rotates together with the driven gear 8b comes into contact with the dog 30a, and the clutch member 30 is driven through the dog 30a. Since the rotation of the clutch member 30 is transmitted to the second cam shaft 16b that is spline-fitted with the clutch member 30, the first and second cam shafts 16a and 1b rotate together under a predetermined phase relationship.

  By the way, in order to make it easy for the dog 30a to enter the engagement recess 31, the rotation direction width S1 of the engagement recess 31 is set to be sufficiently larger than the rotation direction width S2 of the dog 30a. During the rotation of the driven gear 8b, the engaging recess 31 can reliably receive the dog 30a urged toward the connecting position A by the actuator 39. In addition, a one-way clutch 40 is interposed between the first and second camshafts 16a and 1b to allow the first camshaft 16a to rotate in advance with respect to the second camshaft 16b. Since 16b is prevented from precedingly rotating with respect to the first camshaft 16a, the first camshaft 16a on the driving side is advanced with respect to the second camshaft 16b so as to engage with the engaging recess 31. The inner end surface 31a opposite to the rotation direction R can be brought into contact with the dog 30a. At the time of the contact, due to the contact impact, the second cam shaft 16b on the driven side tries to make a preceding rotation with respect to the first cam shaft 16a on the driving side. Therefore, the contact state between the inner end surface 31a of the engagement recess 31 and the dog 30a, that is, the connection state under a predetermined phase between the first and second cam shafts 16a and 1b can be ensured.

  The first and second intake cams 17i and 18i formed on the second and first cam shafts 16b and 16a, respectively, are flush with each other at the base circle portion, but at the nose portion, the first intake cam 17i. Is higher than the second intake cam 18i, and the first and second exhaust cams 17e and 18e respectively formed on the second and first cam shafts 16b and 16a are flush with each other in the base circle portion. However, since the first exhaust cam 17e is higher than the second exhaust cam 18e at the nose portion, the first intake cam 17i and the first intake cam 17i and the second camshafts 16a and 1b are connected in the connected state. The first exhaust cam 17e preferentially swings the intake lifter 25i and the exhaust lifter 25e, moves the intake and exhaust push rods 28i and 28e up and down, and moves the intake and exhaust rocker arms 27i and 27e. To the intake and exhaust valves 12i, thus opening and closing the 12e.

  Thus, when the internal combustion engine E is started, the first intake cam 17i and the first exhaust cam 17e govern the opening and closing of the intake valve 12i and the exhaust valve 12e. As the valve 12e closes, the valve 12i and 12e open periods overlap each other for a certain period of time so that scavenging in the intake stroke is performed reliably, and spark ignition by the spark plug 14 , Enabling smooth start-up and shifting to a stable warm-up state by electric ignition.

  When the warm-up operation of the internal combustion engine E is completed, the engine temperature enters a predetermined high temperature range. Therefore, the electronic control unit 42 deactivates the actuator 39 and deactivates the spark plug 14. E is shifted from the electric ignition operation to the premixed compression self-ignition operation.

  Thus, when the actuator 39 is deactivated, the shift rod 35 is shifted to the non-connection position B by the biasing force of the return spring 37, and the dog 30a is disengaged from the engagement recess 31. As a result, the second camshaft 16b is disconnected from the first camshaft 16a on the driving side and can no longer swing the intake lifter 25i and the exhaust lifter 25e, so this time the first camshaft 16a The second intake cam 18i and the second exhaust cam 18e, which rotate integrally with the first and second members, swing the intake lifter 25i and the exhaust lifter 25e to move the intake and exhaust push rods 28i and 28e up and down, thereby moving the intake and exhaust rocker arms 27i and 27e. Thus, the intake and exhaust valves 12i and 12e are opened and closed.

  Thus, in the premixed compression self-ignition operation state, since the second intake cam 18i and the second exhaust cam 18e respectively control the opening and closing of the intake valve 12i and the exhaust valve 12e, the opening timing of the intake valve 12i as described above. And the closing timing of the exhaust valve 12e are separated by β for a certain period, and the pumping loss of the internal combustion engine E is reduced to improve fuel efficiency and burnt in the combustion chamber 4a during the exhaust stroke. Gas can remain. This residual burned gas is mixed with the new air-fuel mixture in the next intake stroke, effectively increasing the air-fuel mixture temperature, ensuring premixed compression auto-ignition, and at the time of combustion of the air-fuel mixture, Contributes to suppressing the occurrence.

  When the engine E is in a high load state, knocking may occur in the premixed compression self-ignition operation. In such a case, the actuator 39 is operated to move the clutch member 30 to the connection position A in the same manner as at the start. Then, switch to electric ignition operation.

  Incidentally, the clutch member 30 is slidably splined to the second cam shaft 16b, and at the connecting position A, it is involved only in torque transmission from the first cam shaft 16a to the second cam shaft 16b. The shift rod 35 slidably supported in the guide hole 33 of the two cam shafts 16b and the connecting pin 36 connecting the same to the clutch member 30 move the clutch member 30 between the connecting position A and the non-connecting position B. Is not involved in torque transmission. Accordingly, the sliding frictional resistance of the connecting pin 36 and the shift rod 35 is reduced, the sliding of the shift rod 35 by the cooperation of the actuator 39 and the return spring 37 becomes smooth, and the switching response of the clutch member 30 is improved. it can. Further, the clutch member 30, the shift rod 35 and the connecting pin 36 share their roles as described above, so that each load is reduced and durability can be enhanced.

  The present invention is not limited to the above embodiment, and various design changes can be made without departing from the scope of the invention. For example, the present invention can be applied to an internal combustion engine of a different type from the above embodiment. The timing transmission device 8 can also be configured in a form other than a gear type, for example, a chain type or a belt type.

A ... Clutch member connection position B ... Clutch member non-connection position E ... Internal combustion engine S1 ... Rotational width S2 of engagement recess ... Rotational direction width 12i, 12e ... engine valve (intake valve, exhaust valve)
15 .... Variable valve operating device 16 .... Valve-operated cam shaft 16a ... first cam shaft 16b ... first cam shafts 17i, 17e ... first cam (first intake cam, first cam 1 exhaust cam)
18i, 18e ... second cam (second intake cam, second exhaust cam)
30 ... Clutch member 30a ... Dog 31 ... Engagement part (engagement recess)
32 ... Clutch shift means 33 ... Guide hole 34 ... Long hole 35 ... Shift rod 36 ... Connecting pin 39 ... Actuator 40 ... One-way clutch

Claims (3)

The valve camshaft (16) is provided with a first cam (17i, 17e) and a second cam (18i, 18e) having a lower lift than the first cam (17i, 17e). In the variable valve operating apparatus for an internal combustion engine, one operation of the second cam is alternately selected and the engine valve (12i, 12e) is opened and closed by the operation of the selected cam.
A first camshaft (16a) integrally connected to a driven wheel (16b) of the timing transmission device (8) with the second cam (18i, 18e), A second shaft provided through the first cam shaft (16a) coaxially passes through the first cam shaft (16a) so as to be rotatable relative to the first cam shaft (16a) and not axially movable, and includes the first cams (17i, 17e). The first camshaft (16a) is formed with an engaging portion (31), while the second camshaft (16b) is provided with a clutch member (30), which is engaged with the camshaft (16b). A connection position (A) for engaging the portion (31) to connect the first and second camshafts (16a, 16b) in a predetermined phase relationship, and disengaging from the engagement portion (31); Sliding between the first and second cam shafts (16a, 16b) and the unconnected position (B) for releasing the connection. It is spline-fitted to obtain the clutch member (30), and is slidable in the axial direction on the second camshaft (16b) to shift it between the coupling position (A) and the non-coupling position (B). A variable valve operating apparatus for an internal combustion engine, characterized in that clutch shift means (32) supported by the engine is connected. The variable valve operating apparatus for an internal combustion engine according to claim 1,
The clutch shift means (32) is slidably supported in a guide hole (33) formed at the center of the second cam shaft (16b), and the guide hole (33). And a connecting pin (36) for connecting the shift rod (35) to the clutch member (30) through a long hole (34) communicating with the outer peripheral surface of the second cam shaft (16b), A variable valve operating apparatus for an internal combustion engine, characterized in that an actuator (39) capable of operating the shift rod (35) is connected to the shift rod (35). The variable valve operating apparatus for an internal combustion engine according to claim 1,
The engaging portion (31) is constituted by an engaging recess (31) extending along the rotation direction (R) of the first cam shaft (16a), and the clutch member (30) is connected to the connecting position ( A) A dog (30a) that enters and leaves the engaging recess (31) according to the movement to the non-connecting position (B) is provided, and the rotational width (S1) of the engaging recess (31) is set. The dog (30a) is set sufficiently larger than the rotational direction width (S2), and when the dog (30a) enters the engagement recess (31), the dog (30a) is moved into the engagement recess (31). The first and second cam shafts (16a, 16b) are connected in a predetermined phase relationship by contacting the inner end surface (31a) opposite to the rotational direction (R), and A one-way clutch (40) is interposed between the second camshafts (16a, 16b). The direction clutch (40) allows the first cam shaft (16a) to rotate in advance with respect to the second cam shaft (16b), but the second cam shaft (16b) is allowed to rotate to the first cam shaft. (16a) A variable valve operating apparatus for an internal combustion engine, configured to prevent a preceding rotation with respect to (16a).

Images