JP4533418B2 - Variable valve mechanism for engine - Google Patents

Description

The present invention includes a first valve cam and a second valve cam provided on a camshaft, a first valve mechanism that can be operated by the first valve cam to open and close an intake valve, and the second valve cam. A second valve mechanism that can be operated by a valve cam to open and close the intake valve; a transmission mechanism that selectively transmits one of the first and second valve mechanisms to the intake valve; and a control The present invention relates to a variable valve mechanism including a variable valve lift mechanism that continuously changes the lift amount of the intake valve by changing the positions of the first and second valve mechanisms with a shaft.

A variable valve lift mechanism for continuously changing the lift amount of the intake valve; a drive eccentric shaft portion eccentrically fixed to or integrally formed with the intake drive shaft; and a control shaft that is rotationally driven when the lift amount of the intake valve is changed; A control eccentric shaft portion that is eccentrically fixed to or integrally formed with the control shaft, a rocker arm that is rotatably supported by the control eccentric shaft portion, a first end of the rocker arm, and the drive eccentric shaft portion that cooperate with each other. 1 link and a second link that links the other end of the rocker arm and the tip of the rocking cam, and the lift amount of the intake valve is set to almost zero when the engine is stopped. It is known from Patent Document 1 below that the amount is set near the minimum value.
JP 2003-56316 A

  By the way, when the lift amount of the intake valve is set to almost zero when the engine is stopped, the lift amount of the intake valve is reduced and the opening angle of the intake valve is set large when starting the engine (the timing for opening the intake valve is advanced). ) To improve the starting performance. This is because, in order to secure the amount of intake air necessary for starting the engine, it is necessary to increase the lift amount of the intake valve from 0 at the stop to a predetermined value by operating the actuator. This is because if the opening angle is large, the necessary intake air amount can be secured even if the lift amount is small, and the driving load of the actuator is reduced, so that the start can be performed in a short time.

  However, in the above-mentioned conventional one, if the opening angle of the intake valve is set to be suitable when starting the engine, the opening angle of the intake valve becomes inappropriate during operation other than when the engine is started. It was difficult to achieve both output performance.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to achieve both starting performance and output performance in an engine including a variable valve lift mechanism that continuously changes the lift amount of an intake valve.

In order to achieve the above object, according to the first aspect of the present invention, the intake valve is operated by the first valve cam and the second valve cam provided on the camshaft and the first valve cam. a first valve mechanism capable of opening and closing the valve, the second valve-operating mechanism is operated by the second valve operating cam capable of opening and closing driving the intake valve, the first one of the second valve mechanism A transmission mechanism that selectively transmits the operation to the intake valve, and a variable valve lift mechanism that continuously changes the lift amount of the intake valve by changing the positions of the first and second valve operating mechanisms with a control shaft. The maximum lift amount and opening angle of the first valve cam are set larger than the maximum lift amount and opening angle of the second valve cam, and the engine is stopped when the engine is stopped. The intake valve is minimized with a variable valve lift mechanism. When the engine is started, the intake valve is driven to open and close by the first valve cam and the first valve mechanism, and the intake valve is moved from the minimum lift amount to a predetermined lift amount by the variable valve lift mechanism. A variable valve mechanism for an engine is proposed, which is characterized in that it is increased.

  According to the invention described in claim 2, in addition to the structure of claim 1, the valve opening period of the intake valve by the first valve cam overlaps the valve opening period of the exhaust valve. An engine variable valve mechanism is proposed.

According to a third aspect of the invention, in addition to the configuration of the first or second aspect, the first valve mechanism operates only when the engine is started. valve mechanism is Ru been proposed.

The first sub cam 21H of the embodiment corresponds to the first valve mechanism of the present invention, the second sub cam 21L of the embodiment corresponds to the second valve mechanism of the present invention, and the connection mechanism of the embodiment. Corresponds to the transmission mechanism of the present invention .

According to the first aspect, first provided on the cam shaft, the first, while the intake valve actuation of the second valve mechanism for opening and closing the intake valve is operated respectively by the second valve operating cam By selectively transmitting, it is possible to change the maximum lift amount and the opening angle of the intake valve, and by changing the positions of the first and second valve operating mechanisms on the control shaft of the variable valve lift mechanism, The lift amount of the valve can be continuously changed. The variable valve lift mechanism is controlled to the minimum lift amount state when the engine is stopped, and the first valve mechanism is driven by the first valve cam having the maximum lift amount and the opening angle larger than those of the second valve cam when the engine is started. However, since the variable valve lift mechanism shifts from the minimum lift amount state to the predetermined lift amount state, the operation amount of the variable valve lift mechanism until the intake air amount necessary for starting is obtained is minimized, and the engine The starting performance can be improved without impairing the output performance.

  According to the second aspect of the present invention, since the valve opening period of the intake valve by the first valve cam at the start time overlaps with the valve opening period of the exhaust valve, the compression is lowered to prevent the occurrence of knocking. Can do.

According to the third aspect of the present invention, since the first valve operating mechanism having the larger maximum lift amount operates only when the engine is started, the lift amount of the intake valve is adjusted by the variable valve lift mechanism when the engine is not started. be increased, since the second valve mechanism at that time the maximum lift amount is small side is activated, Ru can lift amount of the intake valve is prevented from interfering with the piston becomes excessive.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1 to 9 show an embodiment of the present invention. FIG. 1 is a side view of a variable valve mechanism of an engine, FIG. 2 is a sectional view taken along line 2-2 in FIG. 1, and FIG. -3 sectional view (high lift state of the control arm), FIG. 4 is an exploded perspective view of the main part of the variable valve mechanism of the engine, and FIG. 5 is a sectional view taken along the line 5-5 in FIG. 6) is a sectional view taken along line 6-6 of FIG. 2, FIG. 7 is an explanatory diagram of action corresponding to FIG. 3 (low lift state of the control arm), and FIG. 8 is an explanatory diagram of action corresponding to FIG. 9 is a graph showing the valve timing and lift amount of the intake valve.

  As shown in FIG. 1 to FIG. 4, a pair of intake valves 16, 16 are arranged in a cylinder head 15 constituting a part of the engine body 14 so as to be openable and closable with respect to one cylinder. The variable valve lift mechanism 17 for continuously changing the lift amounts 16 and 16 is displaced in a cam shaft 19 provided with three valve cams 18H, 18L and 18L, and in a plane perpendicular to the axis of the cam shaft 19. The three sub-cams 21H, 21L, 21L, which are supported by the movable movable shaft 20 so as to be swingable and swing by being driven by the three valve cams 18H, 18L, 18L, and the intake valves 16, 16 A pair of rocker arms 22 and 22 that are individually linked and connected and driven by three sub cams 21H, 21L, and 21L, and rocking around shaft portions 23a and 23a parallel to the axis of the camshaft 19. The control arm 23 includes a control arm 23 that holds the movable support shaft 20 at a position that is offset from the shaft portions 23a and 23a, and drive means 24 that swings and drives the control arm 23. By swinging and displacing the movable support shaft 20, the operation characteristics including the lift amount of the intake valves 16, 16 can be continuously changed.

  The valve cams 18H, 18L, 18L are composed of one first valve cam 18H located in the center in the axial direction and two second valve cams 18L, 18L located on both sides in the axial direction. The cam profile of the first valve cam 18H is set to be larger than the cam profiles of the second valve cams 18L and 18L. The three sub cams 21H, 21L, and 21L are located at the axial center and one first sub cam 21H driven by one first valve cam 18H and axially opposite sides thereof. It comprises two second sub cams 21L, 21L driven by two second valve cams 18L, 18L.

  Stems 16a, 16a of the intake valves 16, 16 are slidably fitted into guide cylinders 25, 25 disposed in the cylinder head 15, and retainers 26, 26 provided at the upper ends of the stems 16a, 16; The intake valves 16 and 16 are urged in the valve closing direction by the valve springs 28 and 28 interposed between the retainers 27 and 27 in contact with the cylinder head 15.

  The cylinder head 15 is provided with cam holders 29 and 29 so as to be arranged on both sides of the pair of intake valves 16 and 16, and in cooperation with these cam holders 29 and 29, the camshaft 19 is rotatably supported. Caps 30 and 30 are fastened to the upper surfaces of the cam holders 29 and 26.

  One end portions of the rocker arms 22 and 22 are swingably supported by the control arm 23 via hydraulic tappets 31 and 31. Further, the other end portions of the rocker arms 22 and 22 are provided with valve contact portions 22a and 22a that are in contact with the upper ends of the stems 16a and 16a of the intake valves 16 and 16, respectively. Further, first rollers 33 and 33 are pivotally supported at intermediate portions of the rocker arms 22 and 22 via needle bearings 32 and 32. These first rollers 33 and 33 are individually attached to the rocker arms 22 and 22, respectively. The rolling contact comes into contact with the corresponding second sub cams 21L and 21L.

  The control arm 23 includes a pair of side wall portions 23b, 23b disposed on both sides of the intake valves 16, 16 at intervals along the swing axis, and a first connecting portion between the one end portions of the side wall portions 23b, 23b. A pair of shafts provided on the pair of side wall portions 23b and 23b, which are integrally formed with one connection wall portion 23c and a second connection wall portion 23d connecting the other ends of the side wall portions 23b and 23b. The parts 23a, 23a are fitted in support holes 34, 34... Provided in the cam holders 29, 29 so as to be swingable.

  The swing axis C of the control arm 23, that is, the axis of the shaft portions 23a and 23a is disposed above the stems 16a and 16a of the intake valves 16 and 16, and is provided at the other end of the rocker arms 22 and 22. The valve contact portions 22a and 22a are arranged so as to follow an arc A (indicated by a virtual line in FIG. 3) centering on the swing axis C of the control arm 23 when the intake valves 16 and 16 are closed. It is formed.

  In addition, on the projection onto the plane perpendicular to the swing axis C of the control arm 23, the swing axis C of the control arm 23 is within the extension width W (width shown by the chain line in FIG. 1) above the stems 16a, 16a. Is placed.

  The movable support shaft 20 having an axis parallel to the camshaft 19 passes through the first and second sub cams 21H, 21L, and 21L disposed inside the side walls 23b and 23b of the control arm 23. Both ends are brought into contact with the inner side surfaces of both side wall portions 23b, 23b and fixed by bolts 36, 36. Needle bearings 37 are interposed between the movable support shaft 20 and the first and second sub cams 21H, 21L, and 21L.

  In addition, the portion corresponding to the space between the shaft portions 23a, 23a and the movable support shaft 20 of the control arm 23 of the first and second sub cams 21H, 21L, 21L is formed in a substantially U-shape opened to the camshaft 19 side. A pair of support arm portions 21a extending downward from the camshaft 19 are integrally connected, and a second roller is provided via a needle bearing 39 on a spindle 38 fixed between the tips of the support arm portions 21a. 40 ... are pivotally supported, and the second rollers 40 ... are in rolling contact with the first and second valve cams 18H, 18L, 18L of the camshaft 19, respectively. That is, the first and second sub cams 21H, 21L, and 21L are arranged around the axis of the movable support shaft 20 when the second rollers 40 are in contact with the first and second valve cams 18H, 18L, and 18L of the camshaft 19. Is driven to swing.

  Further, on the side opposite to the camshaft 19 with respect to the support shaft 38, pressure receiving arm portions 21b, 21b are integrally provided on the second sub cams 21L, 21L, respectively, and the pressure receiving arm portions 21b, 21b are provided with second rollers. The spring force for urging the second sub cams 21L and 21L acts on the side where the 40 and 40 are brought into rolling contact with the second valve cams 18L and 18L.

  That is, the second connecting wall 23d provided in the control arm 23 has an end wall 43a at the end opposite to the second sub cams 21L, 21L and extends to the opposite side of the second sub cams 21L, 21L. The bottom cylindrical guide tubes 43, 43 are integrally provided, and are used for lost motion between the contact pieces 44, 44 contacting the pressure receiving arm portions 21b, 21b and the end walls 43a, 43a of the guide tubes 43, 43. The springs 45, 45 are contracted.

  By the way, the lower surfaces of the second sub-cams 21L and 21L are provided with contact surfaces 46 and 46 for bringing the first rollers 33 and 33 of the rocker arms 22 and 22 into rolling contact with each other. A lift part 46a that swings and drives the arm 22 and a base circle part 46b that is equidistant from the axis of the movable support shaft 20 in order to keep the rocker arm 22 in a stationary state are connected. The portion 46a is configured so that the distance between the contact point of the lift portion 46a to the first roller 33 of the rocker arm 22 and the axis of the movable support shaft 20 gradually increases when the second sub cam 21L swings. It is formed so as to extend linearly.

  The first sub cam 21H includes a pressure receiving arm portion 21c at a position corresponding to the contact surface 46 of the second sub cam 21L described above, and the lost motion in which the pressure receiving arm portion 21c is contracted with the control arm 23. When the working spring 35 comes into contact, the second roller 40 of the first sub cam 21H is urged in the direction in which the second roller 40 comes into contact with the first valve cam 18H (see FIG. 6).

  In the first connecting wall portion 23c of the control arm 23, the portions corresponding to the rocker arms 22 and 22 have end walls 47a and 47a at the end opposite to the movable support shaft 20, and the movable support shaft. The bottomed cylindrical tappet mounting cylinders 47 and 47 extending to the opposite side of the cylinder 20 are integrally provided, and the hydraulic tappets 31 and 31 are mounted on the tappet mounting cylinders 47 and 47.

  The hydraulic tappet 31 has a closed cylindrical body 48 fitted and mounted in the tappet mounting cylinder portion 47 with the closed end abutting against the end wall 47a, and a plunger slidably mounted on the body 48. 49, a high pressure chamber 50 formed between the closed end of the body 48 and one end of the plunger 49, and a check valve 52 provided at one end of the plunger 49 interposed between the oil chamber 51 formed in the plunger 49, A spherical head formed at the other end of the plunger 49, which is provided with a return spring 53 provided between the body 48 and the plunger 49 by exerting a spring force that urges the plunger 49 on the side of increasing the volume of the high-pressure chamber 50. At 49a, one end of the rocker arm 22 is pivotably supported.

  The control arm 23 is provided with oil passages 54 and 54 for guiding the hydraulic pressure to the hydraulic tappets 31 and 31 up to the shaft portions 23a and 23a, and from the cylinder head 15 through the shaft portions 23a and 23a. Oil pressure is supplied to the oil passages 54.

  The drive means 24 has a control shaft 56 that has an axis parallel to the movable support shaft 20 and is swingably supported between the cam holders 29 and 29 and the caps 30 and 30, and a drive gear 57 provided on the control shaft 56. An electric motor 58 that rotationally drives the control shaft 56 is provided, and the control arm 23 is driven to swing around the axis of the shaft portions 23a, 23a, that is, the swing axis C by the drive means 24.

  The first connecting wall portion 23c of the control arm 23 is provided with a sector gear 59 disposed in the center between the side wall portions 23b and 23b, and the pair of rocker arms 22 and 22 are arranged on both side walls of the control arm 23. Between the portions 23a and 23a and the sector gear 59, they are respectively arranged so as to partially overlap the sector gear 59 and the side wall portions 23a and 23a in a side view.

  Thus, when the control arm 23 is arranged at the position shown in FIG. 3 by the driving means 24, the lift portions of the contact surfaces 46, 46 of the second sub cams 21L, 21L that swing around the axis of the movable support shaft 20 are provided. The upper ends of the stems 16a, 16a of the intake valves 16, 16 are driven in the valve opening direction at the end opposite to the base circular portions 46b, 46b of the 46a, 46a. The lift amount of 16 is the maximum. Further, when the control arm 23 swings upward as shown in FIG. 7 by the driving means 24, for example, the base circular portions 46b and 46b of the contact surfaces 46 and 46 of the second sub cams 21L and 21L are connected to the intake valves 16 and 16, respectively. The upper ends of the stems 16a and 16a are in contact with each other, and the lift amount h of the intake valves 16 and 16 is minimized in this state.

  That is, when the control arm 23 is driven to swing by the drive means 24, the lift amount of the intake valves 16 and 16 changes. However, the first and second valve cams 18H and 18L are driven by the swing drive of the control arm 23. , 18L also changes the timing of contact with the second rollers 40, so that the opening / closing timing of the intake valves 16, 16 also changes.

Next, based on FIGS. 4 and 5, the first and second valve cams 18H, 18L, 18L and the first and second sub cams 21H, 21L, 21L are selectively operated, and the operation thereof is the intake valve 16. the structure of the coupling mechanism 70 of the lift amount of that is transmitted to the 16 as a transmission mechanism for changing in two steps will be described.

Three pin holes of the same diameter that can be coaxially aligned are provided in the support shafts 38 that support the second rollers 40 of the first and second sub cams 21H, 21L, and 21L via needle bearings 39 . 61, 62, 63 are formed. A first pin 64 is slidably fitted in the pin hole 61 of one second sub cam 21L, and a second pin 65 is slidably fitted in the pin hole 62 of the first sub cam 21H. A third pin 66 is slidably fitted into the pin hole 63 of the second sub cam 21L.

  An oil chamber 68 is formed on the side opposite to the second pin 65 of the first pin 64 whose outer peripheral portion is sealed by the seal member 67, and a coil spring 69 is contracted on the side opposite to the second pin 65 of the third pin 66. The Accordingly, when no hydraulic pressure is applied to the oil chamber 68 (see FIG. 5), the first to third pins 64 to 66 move to the oil chamber 68 side by the elastic force of the coil spring 69, and the three sub cams 21H. , 21L, 21L are coupled so as to swing together. When oil pressure is applied to the oil chamber 68 (see FIG. 8), the first to third pins 64 to 66 move toward the anti-oil chamber 68 against the elastic force of the coil spring 69, and three The sub cams 21H, 21L, and 21L are separated so as to swing independently.

  Accordingly, when the first to third pins 64 to 66 are moved to the positions shown in FIG. 5 and the three sub cams 21H, 21L, and 21L are coupled together, the first valve cam 18H having a large profile swings. The movement of the first sub cam 21H is transmitted to the two second sub cams 21L, 21L, and the lift amount of the intake valves 16, 16 driven by the two second sub cams 21L, 21L via the rocker arms 22, 22 increases. Then, the high valve timing state is set. At this time, the second valve cams 18L and 18L having a small profile are swung away from the second rollers 40 and 40 of the second sub cams 21L and 21L.

  Conversely, when the first to third pins 64 to 66 are moved to the positions shown in FIG. 8 and the three sub cams 21H, 21L, and 21L are separated, the first valve cam 18H having a large profile causes the first sub cam 21H to move. The second sub cams 21L and 21L are swung by the second valve cams 18L and 18L having a small profile, but the swing of the first sub cam 21H is not transmitted to the rocker arms 22 and 22, 2 Since the swing of the sub cams 21L and 21L is transmitted to the intake valves 16 and 16 through the rocker arms 22 and 22, the lift amount of the intake valves 16 and 16 is reduced, and the low valve timing state is set.

  As described above, the lift amount of the intake valves 16 and 16 can be continuously changed by swinging the control arm 23 around the shaft portions 23a and 23a by the variable valve lift mechanism 17 (see FIG. 3 and FIG. 3). (See FIG. 7). Further, if the first and second sub cams 21H, 21L, and 21L are connected by the connecting mechanism 70, the intake valves 16 and 16 can be driven to open and close with a large lift amount by the first valve cam 18H having a large profile. If the second sub cams 21H, 21L, 21L are separated, the intake valves 16, 16 can be opened and closed with a small lift amount by the second valve cams 18L, 18L having a small profile.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  In the present embodiment, the lift characteristics of the intake valves 16 and 16 are controlled continuously (steplessly) between the high lift state (see FIG. 3) and the low lift state (see FIG. 7) by the variable valve lift mechanism 17. Further, the lift characteristics of the intake valves 16, 16 can be controlled in two stages between the high valve timing state (see FIG. 5) and the low valve timing state (see FIG. 8) by the connecting mechanism 70. Therefore, the lift characteristics of the intake valves 16 and 16 can be variously changed by combining the operation state of the variable valve lift mechanism 17 and the operation state of the coupling mechanism 70.

  In FIG. 9, characteristics 1 and 3 indicate that the first and second sub cams 21H, 21L, and 21L are integrally connected by the connecting mechanism 70, and the intake valves 16 and 16 are driven by the first valve cam 18H having a large profile. When the control arm 23 is swung clockwise from the state of FIG. 5 to the state of FIG. 8 by the variable valve lift mechanism 17 (see FIG. 5), the lift amount changes from the high lift state of the characteristic 1 to the characteristic 3 Continuously changes to a low lift state.

  Characteristic 2 and characteristic 4 are states in which the first and second sub cams 21H, 21L, and 21L are separated by the coupling mechanism 70 and the intake valves 16 and 16 are driven by the second valve cams 18L and 18L having a small profile. When the control arm 23 is swung clockwise from the state of FIG. 5 to the state of FIG. 8 by the variable valve lift mechanism 17 (see FIG. 8), the lift amount changes from the high lift state of the characteristic 2 to the low lift of the characteristic 4. It changes continuously to the state.

  In the present embodiment, during normal operation except when the engine is started, the coupling mechanism 70 separates the first and second sub cams 21H, 21L, and 21L, and the second valve cams 18L and 18L connect the intake valves 16 and 16 to each other. While driving, the variable valve lift mechanism 17 controls the lift amount in a decreasing direction at low load (see characteristic 4), and controls the lift amount in an increasing direction at high load (see characteristic 2). Thereby, the output performance of the engine can be ensured.

  On the other hand, when the engine is started, the first and second sub cams 21H, 21L, and 21L are connected by the connecting mechanism 70 and the intake valves 16 and 16 are driven by the first valve operating cam 18H, and the lift is changed by the variable valve lift mechanism 17. The amount is controlled to the starting lift (see characteristic 5).

  The reason is as follows. When the electric motor 58 that is the actuator of the variable valve lift mechanism 17 fails during operation of the engine, the variable valve lift mechanism 17 is configured so that the engine output does not increase against the driver's intention. , 16 is set to be the minimum lift amount (see FIG. 7), so that the lift amount of the intake valves 16, 16 becomes the minimum lift amount even when the engine is stopped when the electric motor 58 stops operating. Therefore, when starting the engine, the electric motor 58 of the variable valve lift mechanism 17 is actuated to change the lift amount of the intake valves 16 and 16 from the minimum lift amount (the lift amount that can obtain the intake air amount necessary for starting). It is necessary to increase it quickly.

  By the way, if the lift amount that can obtain the intake air amount necessary for starting the engine can be reduced, the required operation amount of the electric motor 58 of the variable valve lift mechanism 17 is reduced, and the load of the electric motor 58 is reduced quickly. The amount can be secured. At this time, if the opening angle of the intake valves 16, 16 is large, the intake air amount necessary for starting the engine can be obtained with a small lift amount. Therefore, in this embodiment, the profile is large when the engine is started (the opening angle is small). (Large) The first valve cam 18H is used.

  This will be described with reference to FIG. 9. When the engine is stopped, the intake valves 16 and 16 are in a low lift state at the high valve timing of characteristic 3. From there, the lift amount is slightly increased by the variable valve lift mechanism 17 to shift to the characteristic 5, and the intake air amount necessary for starting the engine quickly can be secured without imposing a large load on the electric motor 58. Can improve the starting performance.

  Since the oil pump is also stopped when the engine is stopped, the supply of the control hydraulic pressure to the switching mechanism 70 is also stopped. At this time, as shown in FIG. 5, the first to third pins 64 to 66 move to the oil chamber 68 side by the elastic force of the coil spring 69, so the first to third sub cams 21H, 21L, and 21L are integrated. Connected, the high valve timing state is automatically realized.

  Characteristic 6 in FIG. 9 shows the lift characteristic of the exhaust valve, and the opening timing of the exhaust valve overlaps with the opening timing of the intake valves 16 and 16 at the start (see the shaded portion). An overlap period is formed. As a result, the compression at the time of starting the engine is prevented from excessively increasing, knocking can be suppressed, and the engine starting performance can be further enhanced.

  Further, in the state of the characteristic 1 in FIG. 9, that is, when the connection mechanism 70 is set to the high valve timing state and the variable valve lift mechanism 17 is set to the high lift state so that the lift amount of the intake valves 16 and 16 is maximized, the lift has occurred. Although the intake valves 16 and 16 may interfere with the top surface of the piston, the state of characteristic 1 is not used in this embodiment, that is, the variable valve lift mechanism 17 when the connection mechanism 70 is in the high valve timing state. Since the lift amount of the intake valves 16, 16 is not made larger than the starting lift amount (see characteristic 5), there is no possibility that the intake valves 16, 16 interfere with the top surface of the piston.

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

  For example, in the embodiment, the drive means 24 for swinging the control arm 23 is constituted by the drive gear 57 and the sector gear 59, but the drive means 24 may be constituted by a cam and a cam follower.

Side view of variable valve mechanism of engine 2-2 sectional view of FIG. Sectional view along line 3-3 in FIG. 2 (high lift state of the control arm) The exploded perspective view of the main part of the variable valve mechanism of the engine 1 is a cross-sectional view taken along line 5-5 in FIG. 1 (when three sub cams are coupled). Sectional view along line 6-6 in FIG. Action explanatory diagram corresponding to FIG. 3 (low lift state of control arm) Action explanatory diagram corresponding to FIG. 5 (a state where three sub cams are separated) Graph showing valve timing and lift amount of intake valve

16 Intake valve 17 Variable valve lift mechanism 18H First valve cam 18L Second valve cam 19 Camshaft 21H First sub cam (first valve mechanism)
21L second sub cam (second valve mechanism)
23 Control arm 38 Support shaft 56 Control shaft 70 Connection mechanism (transmission mechanism)

Claims (3)

A first valve cam (18H) and a second valve cam (18L) provided on the camshaft (19);
Said first valve operating cam (18H) first valve mechanism capable of opening and closing drive and the intake valve (16) actuated by a (21H),
Said second valve operating cam (18L) the second valve mechanism capable of opening and closing drive and the intake valve (16) actuated by the (21L),
A transmission mechanism (70) for selectively transmitting one operation of the first and second valve operating mechanisms (21H, 21L) to the intake valve (16);
A variable valve lift mechanism (17) for continuously changing the lift amount of the intake valve (16) by changing the positions of the first and second valve operating mechanisms (21H, 21L) with a control shaft (56); ,
A variable valve mechanism comprising:
The maximum lift and opening angle of the first valve cam (18H) are set larger than the maximum lift and opening angle of the second valve cam (18L),
When the engine is stopped, the intake valve (16) is controlled to the minimum lift amount by the variable valve lift mechanism (17),
When the engine is started, the intake valve (16) is opened and closed by the first valve cam (18H) and the first valve mechanism (21H), and the intake valve (16) is driven by the variable valve lift mechanism (17). Is increased from the minimum lift amount to a predetermined lift amount.   The variable valve mechanism for an engine according to claim 1, wherein the valve opening period of the intake valve (16) by the first valve cam (18H) overlaps with the valve opening period of the exhaust valve. It said first valve operating mechanism (21H) is characterized in that it operates only at the start of the engine, according to claim 1 or variable valve Organization for an engine according to claim 2.

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