CN101189413A - variable valve gear - Google Patents

Abstract

An arm coupling mechanism 72 is provided as changing means for selectively switching double valve variable control and single valve variable control. The single valve variable control is achieved in a condition, in which a large lift arm 70 and a second rocking cam arm 40R are coupled together with a pin 76. The second rocking cam arm 40R for moving a second valve 16R includes a pin hole 80, in which the pin 76 is inserted, formed therein. The position of the pin hole 80 is set so that a pin switching operation can be executed when control is provided to achieve an operating angle, at which the single valve variable control is to be started for reduced NOx. A second driving cam 14 is adapted to have a cam height greater than a cam height of a first driving cam 12.

Description

variable valve gear

technical field

The present invention relates to a variable valve device, and more particularly to a variable valve device for an internal combustion engine capable of mechanically changing the valve opening characteristic of a valve.

Background technique

For example, Patent Document 1 discloses a variable valve device for an internal combustion engine capable of mechanically changing the valve opening characteristics of a valve. Two rotating cams are fixed on a single camshaft of this variable valve device: a first rotating cam and a second rotating cam. As for the two intake valves set in a single cylinder—the first intake valve and the second intake valve, the first rotary cam drives the opening or closing of the first intake valve, and the second rotary cam drives the opening or closing Second intake valve. Variable valve trains including four-bar linkages are respectively interposed between the first rotary cam and the first intake valve and between the second rotary cam and the second intake valve.

The four-bar linkage of the variable valve train consists of four main elements: the input arm, the transmission arm, the rocker arm, and the control arm. The input arm includes an input portion adjoining the rotating cam. The transmission arm is coupled to the input arm in a swingable manner. While being coupled to the transmission arm in a rockable manner, the rocker arm can also rock around the rotation control shaft to transmit the driving force transmitted from the rotary cam to the output part that opens or closes the intake valve. While being rotatably driven about a rotational control axis, the control arm is also oscillably coupled to the input arm. The valve opening characteristic of the intake valve can be changed mechanically by controlling the pose of the four-bar linkage, thereby changing the position of the rotary cam relative to the input part.

The conventional variable valve device described above further includes a selection mechanism for changing the control method of the valve opening characteristic of the second intake valve from variable control to fixed control, or from fixed control to variable control. More specifically, the variable valve device includes a coupling mechanism that couples a four-bar linkage associated with the first intake valve (first linkage) to a four-bar linkage associated with the second intake valve ( second linkage mechanism). The variable valve device further includes another mechanism for maintaining the posture of the second link mechanism at a posture such that the operation angle of the second intake valve becomes a maximum value or a minimum value when the coupling is disengaged. The coupling mechanism includes a through hole extending in the control arm of each four-bar linkage and a coupling pin inserted in the through hole. The mechanism for maintaining the posture of the second link mechanism when the coupling is disengaged includes a through hole extending in the fixed plate, a through hole extending in the control arm (second control arm) of the second link mechanism, and the aforementioned coupling pins.

The coupling pin always engages a through hole in the second control arm. While remaining engaged with the through hole in the second control arm, the coupling pin is movable toward the control arm (first control arm) side or the fixed plate side of the first linkage mechanism. When the coupling pin moves toward the first control arm side and is inserted into the through hole of the first control arm, the second control arm is coupled to the first control arm through the coupling pin. When the first and second control arms are coupled together, the first link mechanism and the second link mechanism always assume the same posture. Therefore, in this case, the first and second valves can be controlled to have the same valve opening characteristics.

On the other hand, when the coupling pin moves toward the fixed plate side and is inserted into the through hole in the fixed plate, the second control arm is coupled to the fixed plate through the coupling pin. When the second control arm is coupled to the fixed plate, the second link mechanism is fixed to a predetermined pose. In this case, the pose of the first link mechanism is controlled so that the pose of the rotary cam relative to the input section can be changed. This only allows the valve opening characteristic of the first valve to be changed mechanically, while the valve opening characteristic of the second valve is fixed.

Specifically, according to the variable valve apparatus described above, it is possible to selectively execute any one of two different control modes, that is, a control mode in which the first intake valve and the second intake valve have the same valve opening characteristics (dual valve variable control) or a control mode with different valve opening characteristics between the first intake valve and the second intake valve (single valve variable control). Therefore, changing the valve opening characteristic between the first intake valve and the second intake valve, or specifically, changing the lift between the two valves, changes the intake air flow. This creates a swirl flow in the combustion chamber, thereby stabilizing combustion in the combustion chamber.

The present applicant knows the following documents including the above documents as prior art of the present invention.

[Patent Document 1] Japanese Patent Laid-Open No. 2004-100555

Contents of the invention

A mechanism according to the prior art, which is configured such that, when the dual-valve variable control is switched to the single-valve variable control, the second link mechanism temporarily assumes the maximum or maximum value of the operating angle of the second intake valve via the current operating angle. The minimum pose. This method means that when the control mode is switched between dual-valve variable control and single-valve variable control, it is necessary to control the operating angle within the current operating range to its maximum or minimum value. In addition, after selecting a new control mode, it is necessary to move the first intake valve to be variably controlled to the lift required to create an effective difference in intake flow between these intake valves.

Thus, it takes a certain amount of time to switch from the two-valve variable control to the single-valve variable control. In addition, at the time of switching, it is also necessary to control the ignition timing and fuel injection quantity to prevent the torque of the internal combustion engine from undergoing any sudden change. This makes fuel economy worse. However, in the prior art mechanism, no consideration is given to shortening the switching operation time. There is still room for research in the prior art in this respect.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a variable valve apparatus that allows the valve opening characteristic of a valve to be changed from variable control to fixed control, or from fixed control to variable control, and It can realize rapid switching operation between two control modes.

The above object is achieved by a variable valve device in which the control of the valve opening characteristic of at least one valve to be switched among the plurality of valves is changed from control in the variable control mode to control in the fixed control mode or from the fixed control mode Control in variable control mode changes to control in variable control mode. The variable valve device includes a rocker member disposed between a main cam and the valve, the rocker member transmitting pressure of the main cam to the valve. There is provided valve opening characteristic variable means for controlling the pose of the rocking member within a predetermined range to variably control the valve opening characteristic of the valve to be switched. There is also provided valve opening characteristic fixing means for fixedly controlling the valve opening characteristic of the valve to be switched. There is also provided changing means for switching control of the valve opening characteristic of the valve to be switched from control in the variable control mode to control in the fixed control mode or from the fixed control mode The control under switches to the control under the variable control mode. The changing means is configured to allow the valve opening characteristic of the valve to be switched to be changed while the rocking member is in a posture related to an operating range in which switching of the valve opening characteristic of the valve to be switched is required.

In the second aspect of the present invention, the operating range requiring switching of the valve opening characteristic of the valve to be switched according to the first aspect of the present invention includes a low engine speed range for reducing NOx or improving fuel economy or low load range.

In a third aspect of the present invention, the valve opening characteristic variable device includes an intermediate member provided between the main cam and the valve to be switched, and control means for changing the position of the intermediate member . The intermediate member is shared by the plurality of valves including the valve to be switched. A second cam separate from the primary cam is also provided. The valve opening characteristic fixing device includes an input arm rocked in phase with the rotation of the second cam. The changing means engages or disengages the coupling between the rocker member for moving the valve to be switched and the input arm. The second cam is configured to have a greater cam height than the primary cam.

In the fourth aspect of the present invention, the changing means is arranged such that, when the operating range required to switch the valve opening characteristic of the valve to be switched is within a predetermined range, when the rocking member is in the position to achieve the desired The valve opening characteristic of the valve to be switched can be switched when the valve to be switched is in a minimum operating angle and/or minimum lift pose within the predetermined range.

In the fifth aspect of the present invention, the changing means is arranged such that, when the operating range requiring switching of the valve opening characteristic of the valve to be switched is within a predetermined range, when the rocking member is in the position to achieve the desired The valve opening characteristic of the valve to be switched can be switched in a case where the valve to be switched is at a maximum operating angle and/or a maximum lift pose within the predetermined range.

In a sixth aspect of the present invention, the valve opening characteristic variable device includes an intermediate member provided between the main cam and the valve to be switched, and control means for changing the position of the intermediate member . The intermediate member is shared by the plurality of valves including the valve to be switched. A second cam separate from the primary cam is also provided. The valve opening characteristic fixing device includes an input arm rocked in phase with the rotation of the second cam. The changing means includes a pin which engages or disengages the coupling of the pin between the rocker member for moving the valve to be switched and the input arm. The rocking member or the input arm for moving the valve to be switched includes a pin hole into which the pin is inserted. The entrance portion of the pin hole includes a guide surface formed to guide the pin inserted into or removed from the pin hole.

In a seventh aspect of the present invention, the guide surface has an inclination angle with respect to the axis of the pin hole, the inclination angle becoming smaller toward an entrance portion of the pin hole.

In an eighth aspect of the present invention, the profile of the second cam is set such that a phase of the valve to be switched achieved by the second cam is different from a valve phase achieved by the main cam.

According to the first aspect of the invention, the time required for the switching operation is effectively shortened as compared with the case of switching at the maximum or minimum value within the variable range of the valve opening characteristic of the valve to be switched.

When the operating range of the valve opening characteristic of the valve to be switched needs to be switched is a low engine speed range or a low load range for reducing NOx or improving fuel economy, if the valve opening characteristic of the valve to be switched If switching is performed at the maximum or minimum value within the variable range, the time required for the switching operation will be longer. According to the second aspect of the present invention, such operation time can be effectively shortened.

If the intermediate member is shared by a plurality of valves including the valve to be switched, and if the main cam is selected as the drive cam, the main cam drives the valves to provide the same valve opening characteristics. In this case, it is assumed that an attempt is made to switch the valve opening characteristic of the valve to be switched while the rocking member is in a posture of an operating range in which switching of the valve opening characteristic of the valve to be switched is required. If in this case the second cam has the same cam height as the main cam, it is impossible to control the lift of the valve to be switched driven by the second cam to a value greater than the lift of the other valves driven by the main cam . On the other hand, according to the third aspect of the invention, the presence of the intermediate member does not affect the upper limit value of the lift of the valve to be switched controlled by the second cam. Then, with the rocking member in the posture for the desired operating range, the valve opening characteristic of the valve to be switched can be switched.

According to the third aspect of the present invention, the lift of the valve to be switched can be changed to a large lift immediately after the switching operation is completed. In addition, according to the fourth aspect of the present invention, the operation time for controlling the variably controlled other valve to a sufficiently small lift after the switching operation is completed can be further shortened.

According to the fifth aspect of the present invention, at any time after the valve opening characteristic of the valve to be switched has been changed to fixed control, the valves other than the valve to be switched can be operated at the same The operating angle or lift of the valve switched within the predetermined range of the fifth aspect changes within a smaller range than that. This prevents a gap from being created between the second cam and the input arm. Therefore, during the lift operation, noise or impact load can be prevented from being generated between the second cam and the input arm.

According to the sixth aspect of the invention, even if the pin is not axially aligned with the pin hole, since the pin is guided by the guide surface, rotation of the rocking member brings the pin into axial alignment with the pin hole. This enables the coupling of the pins. Therefore, according to the present invention, the operation time of the switching operation can be effectively shortened.

According to the seventh aspect of the present invention, it is possible to reduce the speed at which the rocking member moves when the coupling of the pins is disengaged. Therefore, according to the present invention, it is possible to prevent noise or shock load generated by contact between members during uncoupling of the pins.

According to the eighth aspect of the present invention, the valve opening phase of the valve to be switched driven by the second cam and the valve opening phase of the other valves driven by the main cam can be changed without using any mechanism for changing the valve phase.

Description of drawings

FIG. 1 is a view for illustrating a mechanism provided between a driving cam and valves of a variable valve apparatus according to a first embodiment of the present invention.

FIG. 2 is a view showing the variable valve mechanism shown in FIG. 1 viewed from the axial direction of a camshaft.

FIG. 3 is an exploded perspective view showing a variable valve mechanism and a fixed valve mechanism shown in FIG. 1 .

4A and 4B are views for illustrating position setting of pin holes in the variable valve device shown in FIG. 1 .

5 is a view for illustrating the arrangement of a variable valve device according to a second embodiment of the present invention.

FIG. 6 is a graph showing the valve opening characteristics of the valves realized by the variable valve device.

Fig. 7 is a view for illustrating a modified example of the arrangement of the variable valve device according to the second embodiment of the present invention.

Fig. 8 is a graph showing the valve opening characteristics of the valves realized by the variable valve device.

FIG. 9 shows a torque graph for illustrating an operating range when single valve variable control is performed in a variable valve apparatus according to a third embodiment of the present invention.

FIGS. 10A and 10B are views for illustrating problems occurring when the pin switching operation is performed on the small operation angle side of the range in which the single-valve variable control is performed.

11A and 11B are views for illustrating operations when setting of a pin switching operation is made according to the third embodiment of the present invention.

Fig. 12 is a view for illustrating the arrangement of a variable valve device according to a fourth embodiment of the present invention.

13 is a cross-sectional view for illustrating the arrangement of an arm coupling mechanism for a fourth embodiment of the present invention.

14A and 14B show enlarged views of part A of FIG. 13 .

15A and 15B are views for illustrating the pin switching operation of the fourth embodiment of the present invention.

FIG. 16 is a view for illustrating the operation of the second rocking cam arm during the pin switching operation.

FIG. 17 is an enlarged view showing part A of FIG. 13 .

Detailed ways

first embodiment

[Structure of variable valve device]

FIG. 1 is a view for illustrating a mechanism provided between a driving cam and valves of a variable valve apparatus 1 according to a first embodiment of the present invention. It is assumed here that each cylinder of the internal combustion engine has two intake valves and two exhaust valves. The arrangement shown in FIG. 1 is used as a mechanism for driving two intake valves or two exhaust valves provided in a single cylinder.

Referring to FIG. 1 , a camshaft 10 of a variable valve device 1 provides two drive cams 12 , 14 for each cylinder. Two valves—a first valve 16L and a second valve 16R—are arranged symmetrically about one (first driving cam) 12 of the two driving cams. Each variable valve mechanism 20L, 20R is provided between the first drive cam 12 and each valve 16L, 16R. The variable valve train 20L, 20R operatively couples the lift motion of each valve 16L, 16R to the rotational motion of the first drive cam 12 .

The other of the two driving cams (the second driving cam 14 ) is arranged such that the second valve 16R is interposed between the first driving cam 12 and the second driving cam 14 . The fixed valve mechanism 30 is interposed between the second drive cam 14 and the second valve 16R. The stationary valve train 30 operatively couples the lift motion of the second valve 16R to the rotational motion of the second drive cam 14 . The variable valve device 1 is provided so that the lift motion coupling element of the second valve 16R can be selected between the variable valve mechanism 20R and the fixed valve mechanism 30 .

(1) Detailed structure of the variable valve mechanism

Referring first to FIG. 2 , the arrangement of the variable valve trains 20L, 20R will be described in detail. FIG. 2 is a view showing the variable valve mechanism 20 shown in FIG. 1 viewed from the axial direction of the camshaft 10 . Since the left and right variable valve mechanisms 20L, 20R are substantially symmetrical with respect to the first driving cam 12, the left and right variable valve mechanisms 20L, 20R will be described here without distinction. In this specification and its drawings, when the left variable valve mechanism 20L and the right variable valve mechanism 20R are not distinguished, this mechanism will be simply referred to as the variable valve mechanism 20 . Similarly, each component of the variable valve train 20L, 20R, as well as symmetrically disposed components including the valves 16L, 16R, will be identified with a symbol without the L or R attached, unless it is necessary to distinguish between left and right components. Method abbreviation.

Referring to FIG. 2 , in the variable valve device 1 , a rocker arm 32 is supported by the valve 16 . The variable valve mechanism 20 is disposed between the first driving cam 12 and the rocker arm 32 and continuously changes the operational coupling condition between the rotational motion of the first driving cam 12 and the rocking motion of the rocker arm 32 .

As will be described below, the variable valve mechanism 20 includes, as its main components, a control shaft 34 , a control arm 36 , a link arm 38 , a rocker cam arm 40 , a first roller 42 and a second roller 44 . The control shaft 34 is arranged to extend parallel to the camshaft 10 . The rotation angle of the control shaft 34 can be controlled to an arbitrary value by means not shown (for example, a motor, etc.).

The control arm 36 is integrally fixed to the control shaft 34 by bolts 46 (see FIG. 1 ). A control arm 36 projects radially from the control shaft 34 . A curved link arm 38 is mounted on this protrusion. The rear end of the link arm 38 is rotatably coupled to the control arm 36 using a pin 48 . The pin 48 is offset from the center of the control shaft 34 and serves as a fulcrum for the rocking motion of the link arm 38 .

The rocking cam arm 40 , which is rockably supported on the control shaft 34 , is disposed such that its front end faces the upstream side in the rotation direction of the first driving cam 12 . The swing cam arm 40 includes a slide surface 50 formed on a side opposite to the first drive cam 12 . The sliding surface 50 contacts the second roller 44 . The slide surface 50 is formed as a curved surface such that the distance from the first drive cam 12 becomes gradually smaller as the second roller 44 moves from the front end side of the swing cam arm 40 toward the axis of the control shaft 34 . A rocking cam surface 52 is formed on a side of the rocking cam arm 40 opposite to the sliding surface 50 . The rocking cam surface 52 includes a non-operation surface 52a and an operation surface 52b. The non-operating surface 52a is formed such that the distance from the swing center of the swing cam arm 40 is constant. The operation surface 52b is formed such that the distance from the operation surface 52b to the axis center of the control shaft 34 gradually becomes larger as the operation surface 52b moves away from the non-operation surface 52a.

The first roller 42 and the second roller 44 are interposed between the sliding surface 50 of the rocker cam arm 40 and the peripheral surface of the first driving cam 12 . More specifically, the first roller 42 is arranged to contact the peripheral surface of the first driving cam 12 , and the second roller 44 is arranged to contact the sliding surface 50 of the rocking cam arm 40 . Both the first roller 42 and the second roller 44 are rotatably supported on a coupling shaft 54 fixed to the front end portion of the aforementioned link arm 38 . The link arm 38 is pivotable about a pin 48 . Accordingly, the first and second rollers 42 , 44 can rock along the sliding surface 50 and the peripheral surface of the first driving cam 12 , respectively, while maintaining a predetermined distance from the pin 48 .

A lost motion spring not shown is hooked onto the swing cam arm 40 . Lost springs are compression springs. The urging force from the lost motion spring acts as an urging force that allows the sliding surface 50 to urge the second roller 44 and press the first roller 42 against the first drive cam 12 . Therefore, the first roller 42 and the second roller 44 are correctly positioned between the sliding surface 50 and the peripheral surface of the first driving cam 12 by being sandwiched from both sides. The lost motion spring is not limited to a compression spring; instead, the spring may be a torsion spring, for example.

The aforementioned rocker arm 32 is disposed below the rocker cam arm 40 . The rocker arm 32 includes a rocker roller 56 disposed opposite the rocker cam surface 52 . The rocking roller 56 is rotatably attached to the middle of the rocker arm 32 . The rocker arm 32 has a first end supported by a valve stem 58 of the valve 16 . The rocker arm 32 also has a second end rotatably supported by a hydraulic lash adjuster 60 . In the lift operation, the valve stem 58 is urged in the closing direction, ie, the direction in which the rocker arm 32 is pushed upward by an unillustrated valve spring. Additionally, the rocker roller 56 is pressed against the rocker cam surface 52 of the rocker cam arm 40 by this urging force and the hydraulic lash adjuster 60 .

According to the arrangement of the variable valve mechanism 20 , when the first driving cam 12 rotates, the pressure of the first driving cam 12 is transmitted to the sliding surface 50 through the first roller 42 and the second roller 44 . Accordingly, the contact point between the rocking cam surface 52 and the rocking roller 56 moves from the non-operating surface 52 a to the operating surface 52 b, thereby pushing the rocker arm 32 downward, opening the valve 16 .

In addition, depending on the arrangement of the variable valve mechanism 20 , changing the rotation angle of the control shaft 34 changes the position of the second roller 44 on the sliding surface 50 . This changes the swing range of the swing cam arm 40 in the lift operation. More specifically, when the control shaft 34 rotates counterclockwise as shown in FIG. 2 , the second roller 44 on the sliding surface 50 moves toward the front end side of the rocking cam arm 40 . As the angle of counterclockwise rotation of the control shaft 34 as shown in FIG. It starts to act on the rocker arm 32 and needs to rotate for a period of time when it stops up. Specifically, according to the variable valve mechanism 20 , as viewed in FIG. 2 , rotating the control shaft 34 counterclockwise makes the operating angle and lift of the valve 16 smaller. On the other hand, rotating the control shaft 34 clockwise makes the operating angle and lift of the valve 16 larger when viewed in FIG. 2 .

(2) Detailed structure of fixed valve mechanism

The stationary valve train 30 will be described in detail below with reference to FIGS. 1 and 3 .

Referring to FIG. 1 , the fixed valve mechanism 30 is disposed between the second driving cam 14 and the second rocking cam arm 40R. The stationary valve train 30 operatively couples the rocking motion of the second rocking cam arm 40R to the rotational motion of the second drive cam 14 . The stationary valvetrain 30 includes a high-lift arm 70 and an arm coupling mechanism 72 (see FIG. 3 ). The high lift arm 70 is driven by the second drive cam 14 . An arm coupling mechanism 72 couples the high-lift arm 70 to the second rocker cam arm 40R.

The high lift arm 70 is disposed on the control shaft 34 side by side with the second rocker cam arm 40R. The high lift arm 70 is rotatable independently of the second rocker cam arm 40R. The input roller 74 is rotatably supported by the high lift arm 70 . The input roller 74 contacts the peripheral surface of the second drive cam 14 . A lost motion spring, not shown, hooks onto the high-lift arm 70 . The spring force of the lost motion spring acts as an urging force that urges the input roller 74 upward against the peripheral surface of the second drive cam 14 .

FIG. 3 is an exploded perspective view showing the variable valve mechanism 20 and the fixed valve mechanism 30 shown in FIG. 1 . Referring to FIG. 3 , the high lift arm 70 includes a pin 76 capable of advancing toward and retracting from the second rocker cam arm 40R. The high-lift arm 70 also includes a hydraulic chamber 78 formed therein. The hydraulic chamber 78 has an opening on the second swing cam arm 40R side. Pin 76 fits into hydraulic chamber 78 . Hydraulic oil is supplied to the hydraulic chamber 78 through an unillustrated hydraulic path. When the hydraulic pressure inside the hydraulic pressure chamber 78 is increased by the above arrangement, the pin 76 is designed to be pushed out of the hydraulic pressure chamber 78 toward the second rocking cam arm 40R by hydraulic pressure.

On the other hand, the second rocking cam arm 40R includes a pin hole 80 formed therein. The pin hole 80 has an opening on the high-lift arm 70 side. The pin 76 and the pin hole 80 are arranged on the same circular arc around the control shaft 34 . This arrangement produces the following results. Specifically, the pin hole 80 is aligned with the pin 76 when the second rocker cam arm 40R is at a predetermined rotational angle relative to the high-lift arm 70 . The return spring 82 and the piston 84 are placed in the pin hole 80 in this order from the rear to the front.

According to the foregoing arrangement, when the pin hole 80 is aligned with the pin 76 , the pin 76 abuts the piston 84 . If the hydraulic pressure pushing the pin 76 in the hydraulic chamber 78 is greater than the force of the back spring 82 pushing the piston 84, then the pin 76 advances into the pin hole 80, just as the pin 76 pushes the piston 84 into the pin hole 80. When the pin 76 is inserted into the pin hole 80 , the second rocker cam 40R and the high lift arm 70 are coupled together by the pin 76 . Specifically, the pin 76 , the hydraulic chamber 78 supplied with hydraulic oil, the pin hole 80 , the return spring 82 , and the piston 84 constitute the arm coupling mechanism 72 .

It is provided in the variable valve apparatus 1 that the pin 76 and the pin hole 80 are aligned with each other when the second rocker cam arm 40R is positioned at a predetermined rotation angle with respect to the large lift arm 70 . When the pin 76 is properly aligned with the pin hole 80, the pin 76 is inserted into the pin hole 80, so that the high lift arm 70 is coupled with the second rocker cam arm 40R. In the variable valve apparatus 1, by coupling the large lift arm 70 to the second rocker cam arm 40R using the arm coupling mechanism 72, the elements operatively coupled to the lift movement of the second valve 16R can be changed from The variable valve mechanism 20R is switched to the fixed valve mechanism 30 . Conversely, by decoupling between the high-lift arm 70 and the second rocker cam arm 40R by the arm coupling mechanism 72, the elements operatively coupled to the lift motion of the second valve 16R are decoupled from the fixed valve The mechanism 30 is switched to the variable valve mechanism 20R.

When the high lift arm 70 and the second rocker cam arm 40R are not coupled together, the rotational motion of the camshaft 10 is transferred from the first drive cam 12 to the first rocker cam via the first roller 42 and the second roller 44. Each sliding surface 50 of the arm 40L and the second rocking cam arm 40R. Therefore, in this case, by being operatively coupled to the rotation of the control shaft 34, control can be provided such that the operating angle and lift of the first valve 16L have the same characteristics as those of the second valve 16R. (double valve variable control).

On the other hand, when the high lift arm 70 and the second rocking cam arm 40R are coupled together, the rotational motion of the camshaft 10 is transmitted from the second driving cam 14 to the second rocking cam arm 40R via the high lift arm 70 . The high lift arm 70 and the second rocker cam arm 40R are coupled together under rotation of the control shaft 34 to move the second roller 44R on the slide surface 50R to a position described below with reference to FIG. 4 . Therefore, the valve opening characteristic of the second valve 16R is mechanically defined by the shape and positional relationship of the second drive cam 14, the high lift arm 70 and the second rocker cam arm 40R. Thus, regardless of the rotation angle of the control shaft 34, the valve opening characteristic of the second valve 16R is fixed and constant. On the other hand, the rotational motion of the camshaft 10 is transmitted from the first driving cam 12 to the first rocking cam arm 40L via the first roller 42 and the second roller 44L. Therefore, in this case, the valve opening characteristic of the first valve 16L varies with the rotation angle of the control shaft 34 in the same manner as when the large lift arm 70 and the second rocker cam arm 40R are not coupled together.

As described above, according to the variable valve device 1, when the large lift arm 70 and the second rocking cam arm 40R are coupled together, only the valve opening characteristic of the first valve 16L can be variably controlled (single valve variable control). The variable valve device 1 allows both the lift and the operating angle of the valve 16 to be continuously varied as described above. Throughout the remainder of this specification, the "lift and operating angle" of the valve 16 may be referred to simply as the "operating angle" or "lift" of the valve 16 unless otherwise stated. (3) Setting of pin hole position and cam profile in the first embodiment

4A and 4B are views for illustrating the position setting of the pin hole 80 in the variable valve device 1 shown in FIG. 1 . More specifically, FIG. 4A is a view showing the position setting of the pin holes in the variable valve device A referred to as a comparative configuration of the variable valve device 1 according to the first embodiment of the present invention. 4B is a view showing the position setting of the pin hole 80 in the variable valve device 1 according to the first embodiment of the present invention. It is assumed that the variable valve device A for comparison has the same arrangement as the variable valve device 1 according to the first embodiment of the present invention except for the pin hole position setting and the cam height of the second drive cam. Here, the contact point between the rocking roller 56 and the second rocking cam arm 40R will be referred to as "roller contact point X", and the boundary point between the non-operating surface 52a and the operating surface 52b of the second rocking cam arm 40R will be referred to as "Lift starting point Y". In addition, the angle formed between the straight line connecting the rotation center P of the second rocking cam arm 40R and the rotation center Q of the rocking roller 56 and the straight line connecting the rotation center P and the lift starting point Y will be referred to as "arm angle θ ".

From the viewpoint of productivity in producing the camshaft 10 provided with the first driving cam 12 and the second driving cam 14, it is preferable that the first driving cam 12 and the second driving cam 14 have the same cam profile. In the variable valve device A shown in FIG. 4A, the first driving cam and the second driving cam are arranged to have the same cam profile. In the variable valve device A, no matter the control mode is double valve variable control or single valve variable control, the second roller on the arm side of the second rocking cam tries to transmit the pressure of the first driving cam to the second rocking cam The sliding surface of the arm. Therefore, in the case where the first drive cam and the second drive cam are set to have the same cam height, if the pin hole positions are set such that the lift achieved by the fixed valve train is smaller than that variably achieved by the variable valve train The maximum lift, the valve driven by the variable valve mechanism after reaching the maximum lift will be further driven by the variable valve mechanism. Therefore, single-valve variable control is rendered unavailable.

Therefore, in order to independently control the operating angle of the second valve on the fixed side while realizing the maximum variable range of the operating angle by the variable valve mechanism in the single-valve variable control, it is necessary to set the pin hole position so that the second rocking The pose of the cam arm can realize the maximum operating angle of the variable range obtained by the variable valve train or more. The variable valve device A shown in FIG. 4A shows the setting of the pin hole position in consideration of the above-mentioned matters.

More specifically, FIG. 4A shows the situation where the pressure of the drive cam does not act on the second rocker cam arm. FIG. 4A also shows the situation where the pose of the second rocking cam arm is controlled by the control shaft to achieve the maximum operating angle. In the variable valve device A, the position of the pin hole in the second rocking cam arm is set so that the pin is aligned with the pin hole when the second rocking cam arm assumes the above posture. The arm angle θ in this case is called θ1. By setting the position of the pin hole in the above manner, since the lift difference between the two valves is sufficiently enlarged, it allows a more effective swirl flow to be formed.

On the other hand, in the variable valve device 1 according to the first embodiment of the present invention, the following matters are considered in determining the position of the pin hole 80 . Specifically, in an internal combustion engine, in order to generate an effective swirl flow in the combustion chamber, and in, for example, a low load operating range or a low engine speed range in which the operating angle of the valve 16 is about 100 to 200° CA - With the ultimate goal of reducing NOx emissions, a request for single-valve variable control may be issued. Similarly, in an internal combustion engine, in a low-load operating range or a low engine speed range, for example, with the ultimate goal of improving fuel economy, a request for single-valve variable control may be issued. After receiving such a request, in the internal combustion engine, with the aim of reducing NOx or improving fuel economy, the range of double valve variable control is switched to single valve variable control is set to a predetermined low engine speed range or low load operation scope.

In the variable valve apparatus 1 according to the first embodiment of the present invention, the position of the pin hole 80 on the second rocker cam arm 40R is set to satisfy the following conditions. Specifically, referring to FIG. 4B , in the case where the arm angle θ is an angle θ2 greater than the above-mentioned angle θ1, or in other words, when the posture of the second rocking cam arm 40R is controlled by the control shaft 34 so that the arm angle θ is variable At operating angles in the middle of the variable range of valve 16 achieved by valve train 20 , pin 76 should be aligned with pin hole 80 . In other words, the position of the pin hole 80 is set so that when the second rocking cam arm 40R is in the operation required to realize the switching operation from the double-valve variable control to the single-valve variable control (hereinafter sometimes simply referred to as "pin switching operation") This pin switching operation can be performed when the pose is in the range of operation angles.

More specifically, according to the first embodiment of the present invention, the position of the pin hole 80 is set so that when the operating angle is controlled to be in the range of about 100 to 200° CA, that is, when the operating angle is controlled for starting a single The pin switching operation can be performed while the valve is variably controlled to reduce NOx or an operating angle for a related purpose. In addition, the position of the pin hole 80 is set so that it is on the minimum operation angle side (in the following case, when the second When the pose assumed by the rocking cam arm 40R produces an operation angle of 100° CA), the pin switching operation can be performed.

In the variable valve apparatus 1 according to the first embodiment of the present invention, the profiles of the first driving cam 12 and the second driving cam 14 are set such that the cam height of the second driving cam 14 is greater than that of the first driving cam 12 , as shown in Figure 4B. Specifically, the cam height of the second drive cam 14 is set so that the operating angle of the second valve 16R becomes equal to or greater than the maximum value of the operating angle of the first valve 16L driven by the variable valve mechanism 20 when the pin is coupled. value.

Perform the above pin switching to follow the steps given below. Specifically, an operating time T1 is required during which the control shaft 34 is driven for changing the operating angular posture of the second rocking cam arm 40R in the current operating state of the internal combustion engine to allow the pin hole 80 to be aligned with the pin 76 The operating angle pose of . When the pin switching operation is completed and the second rocker cam arm 40R is coupled to the large lift arm 70 , the lift motion of the second valve 16R is immediately switched to operation performed by the fixed valve train 30 . However, for the first valve 16L driven by the variable valve mechanism 20, an operation time T2 is required after the completion of the pin switching operation. During this time T2, the first rocker cam arm 40L moves to achieve a small operating angle pose capable of generating the desired swirl flow.

According to the arrangement of the variable valve apparatus 1 of the first embodiment of the present invention, the pin switching operation is performed when the second rocking cam arm 40R assumes the operation angle posture requiring the aforementioned pin switching operation. Therefore, the operation time T1 can be shortened compared with the operation time in the variable valve device A (shown in FIG. 4A ) in which the pin hole position is set to the maximum value according to the variable range of the operation angle of the variable valve mechanism 20 . In the variable valve device 1 , it is arranged such that the second drive cam 14 has a cam height greater than that of the first drive cam 12 . This allows the operation angle of the second valve 16R driven to achieve a constant value in the single-valve variable control to be set equal to or greater than the maximum lift achieved by the variable valve mechanism 20 . In addition, according to the first preferred embodiment of the present invention, a method is adopted to change the cam height between the first driving cam 12 and the second driving cam 14, thereby realizing the above-mentioned characteristics of the second valve 16R. This allows the operation angle of the second valve 16R to be changed to a desired large operation angle immediately after the pin switching operation is completed.

As mentioned earlier, after the pin coupling is in place, an operation time T2 is required, during which the first rocking cam arm 40L moves from the operational angular position in which the pin coupling operation is performed to the position capable of generating the desired swirl flow. Small operating angle pose. Compared with the variable valve device A (shown in FIG. 4A ) in which the pinhole position is set to the maximum value according to the variable range of the operating angle of the variable valve mechanism 20 , the variable valve device according to the first embodiment of the present invention 1 can shorten this operation time T2.

To generate sufficient swirl flow, it is effective to make the lift difference between the first valve 16L and the second valve 16R larger. Therefore, the operating angular pose of the first rocker cam arm 40L controlled to achieve this desired swirl flow after pin coupling is substantially small. In the variable valve device 1 according to the first embodiment of the present invention, as described above, the position of the pin hole 80 is set to allow the pin switching operation to be performed at the minimum operating angle of the range in which the pin switching operation is required. Therefore, it is possible to promptly change the operation angle posture of the first swing cam arm 40L to a sufficiently small operation angle posture of the target. Specifically, the operation time T2 can be shortened more effectively.

Correspondence between elements of the first embodiment of the present invention and elements of other aspects of the present invention is as follows. Specifically, respectively, the first valve 16L in the first embodiment corresponds to the "valve to be switched" in the first aspect of the present invention; the rocking cam arm 40 in the first embodiment corresponds to the first aspect of the present invention The "rocking member"; the control shaft 34, the control arm 36, the link arm 38, the first roller 42, the second roller 44, and the sliding surface 50 in the first embodiment correspond to the "valve" of the first aspect of the present invention The opening characteristic variable device"; the large lift arm 70 in the first embodiment corresponds to the "valve opening characteristic fixing device" in the first aspect of the present invention; the arm coupling device 72 in the first embodiment corresponds to the present invention The "changing means" of the first aspect.

Similarly, respectively, the first roller 42 and the second roller 44 in the first embodiment correspond to the "intermediate member" in the third aspect of the present invention; the control shaft 34, the control arm in the first embodiment 36 and the link arm 38 correspond to the "control device" of the third aspect of the present invention; the second driving cam 14 in the first embodiment corresponds to the "second cam" of the third aspect of the present invention; and in the first embodiment The high-lift arm 70 corresponds to the "input arm" of the third aspect of the present invention.

second embodiment

A second embodiment of the present invention will be described below with reference to FIGS. 5 to 8 .

FIG. 5 is a view for illustrating the arrangement of a variable valve device 90 according to a second embodiment of the present invention. The variable valve apparatus 90 according to the second embodiment of the present invention has the same arrangement as the variable valve apparatus 1 according to the first embodiment of the present invention except for the arrangement of the camshaft 92 . Specifically, in the variable valve device 90, the position of the pin hole 80 is also set so that when the second rocking cam arm 40R is in the switching operation for realizing the variable control from the double valve to the variable control of the single valve (the pin switching operation ) at the pose of the operation angle of the operation range required, the pin switching operation can be performed.

Referring to FIG. 5 , the variable valve device 90 has the same arrangement as that of the first embodiment, in which the second driving cam 96 has a cam height greater than that of the first driving cam 94 . Additionally, the first drive cam 94 is mounted on the camshaft 92 at an angle different from that of the second drive cam 96 on the camshaft 92 . Specifically, the second drive cam 96 is fixed to the camshaft 92 at a position deflected by a predetermined angle α relative to the advancing side of the first drive cam 94 .

FIG. 6 is a graph showing the valve opening characteristics of the valve 16 realized by the variable valve device 90 . According to the arrangement of the variable valve device 90 described above, the valve opening timing of the second valve 16R driven by the second drive cam 96 can be advanced with respect to the variable control valve opening timing of the first valve 16L, so that during single valve variable control A given valve opening characteristic can be achieved by the large lift arm 70 and the second rocking cam arm 40R. According to this setting for the camshaft 92, after first creating a vacuum in the cylinder by opening the second valve 16R, the first valve 16L controlled to provide a small operating angle can be opened. This increases the flow velocity of the intake air when the first valve 16L on the small operating angle side is opened, allowing effective swirl flow to be generated. This effect is achieved without using a mechanism for changing the phase of the valves 16 (VVT mechanism).

According to the second embodiment of the present invention, it is provided that the second drive cam 96 is fixed to the camshaft 92 at a position deflected by a predetermined angle α relative to the advance side of the first drive cam 94 . The technique adopted to change the phase of the two cams is not limited to the technique in the present invention. FIG. 7 is a view for illustrating the arrangement of such a modified example. In the variable valve device 100 shown in FIG. 7 , unlike the variable valve device 90 shown in FIG. 5 , the first drive cam 102 is fixed at a position deflected by a predetermined angle β relative to the advance side of the second drive cam 104 .

FIG. 8 is a view showing the valve opening characteristics of the valve 16 realized by the variable valve device 100 . According to the arrangement of the variable valve device 100 described above, during single-valve variable control, the valve opening time of the first valve 16L variably controlled by the variable valve mechanism 20 can be compared with that of the second valve 16R driven by the fixed valve mechanism 30 The valve opening time is advanced. According to this setting for the camshaft 106, the pumping loss can be effectively reduced by first opening the first valve 16L before generating vacuum in the cylinder. This effect can be achieved without using a mechanism (VVT mechanism) that changes the phase of the valves 16 .

third embodiment

A third embodiment of the present invention will be described below with reference to FIGS. 9 to 11A and 11B.

The variable valve device 110 according to the third embodiment of the present invention has the same arrangement as the variable valve device 1 according to the first embodiment of the present invention except for the following two points. Specifically, when the switching operation (pin switching operation) from the two-valve variable control to the single-valve variable control is performed, the pose of the second rocking cam arm 40R is different. In addition, the height of the second driving cam 114 is different from that of the first driving cam 112 .

FIG. 9 is a torque graph showing an operating range in which single-valve variable control is performed in a variable valve device 110 according to a third embodiment of the present invention. Referring to FIG. 9 , the dual-valve variable control in which both valves are set to realize a large operating angle is performed in a heavy load, high speed range. Single-valve variable control in which only the first valve 16L is changed to provide a small operating angle is performed in a range other than the heavy-load, high-speed range. In the aforementioned first embodiment, it is arranged that the pin switching operation is performed on the minimum operation angle side of the range in which such single-valve variable control is performed. On the other hand, the variable valve device 110 according to the third embodiment of the present invention is characterized in that the pin switching operation is performed on the maximum operation angle side of the range in which such single valve variable control is performed.

10A and 10B are views for illustrating problems that occur when the pin switching operation is performed on the small operation angle side of the range in which the single-valve variable control is performed. FIG. 10A is a view showing a state where the second roller 44 contacting the rocking cam arm 40 is located on the front end side of the rocking cam arm 40 , that is, a small operation angle control state. 10B is a diagram showing that in the situation shown in FIG. 10A, the pin switching operation is performed to set the single-valve variable control state and then the control shaft 34 is rotated to move the second roller 44 toward the axis center of the control shaft 34, that is, the large operating angle. A view of the situation that controls the state. In the case shown in FIG. 10B , a gap is generated between the second drive cam 14 on the fixed operating angle side and the input roller 74 . This is due to the following reasons. Specifically, the second rocking cam arm 40R and the large lift arm 70 are coupled together using a pin 76 in the situation shown in FIG. As a result, the pose of the high-lift arm 70 changes. The gap thus created between the second drive cam 14 and the input roller 74 causes the second drive cam 14 to repeatedly contact the input roller 74 in each lift motion. Noise and shock loads are therefore generated upon contact.

11A and 11B are views for illustrating operations performed when setting is made for a pin switching operation according to the third embodiment of the present invention. FIG. 11A is a view showing a situation where the second roller 44 is located at the position of the maximum operating angle of the range in which the single-valve variable control is produced. According to the third embodiment of the present invention, the second rocking cam arm 40R includes the pin hole 116 disposed therein so that the pin switching operation can be performed in the above-mentioned case. FIG. 11B is a diagram showing that in the situation shown in FIG. 11A, the pin switching operation is performed to set the single valve variable control state and then the control shaft 34 is rotated to move the second roller 44 toward the front end side of the rocking cam arm 40, that is, a small operation. A view of the situation where Angular controls the state. In the case shown in FIG. 11B , the first rocking cam arm 40L on the variable operation angle side keeps in contact with the second roller 44; A gap is created between the second rocking cam arm 40R on the corner side and the second roller 44 .

As described above, according to the setting made in the third embodiment of the present invention, the single-valve variable control is always performed on the operation angle side smaller than the operation angle at which the pin switching operation is performed. Therefore, during the single-valve variable control, a gap is generated between the second rocking cam arm 40R and the second roller 44; however, since there is no gap between the second driving cam 14 and the input roller 74, unlike the The arrangement shown in 10A and 10B produces no noise or shock loads during the lift movement.

Fourth Embodiment

A fourth embodiment of the present invention will be described below with reference to FIGS. 12 to 17 .

FIG. 12 is a view for illustrating the arrangement of a variable valve device 120 according to a fourth embodiment of the present invention. Referring to FIG. 12 , a variable valve device 120 according to a fourth embodiment of the present invention has the same arrangement as that of the variable valve device 1 according to the first embodiment of the present invention except for the following points. Specifically, the first drive cam 12 for moving the first roller 42 has the same profile as the second drive cam 122 for moving the input roller 74 . In addition, the arm coupling mechanism 124 has a different arrangement from its counterpart in the first embodiment of the present invention.

More specifically, in the arm coupling mechanism 124 according to the fourth embodiment of the present invention, the axis of the pin 76 is aligned with the axis of the pin hole 128 when the second rocking cam arm 126R becomes the posture realizing the maximum operation angle. FIG. 12 shows a state where the second rocking cam arm 126R is in a posture realizing a maximum operating angle less by a predetermined value with respect to the pin hole 128 arranged as described above. Specifically, FIG. 12 shows a situation where the pin 76 is not axially aligned with the pin hole 128 . The fourth embodiment of the present invention is characterized by allowing the arm coupling mechanism 124 to perform the pin switching operation in the situation shown in FIG. 12 .

FIG. 13 is a cross-sectional view for illustrating an arrangement of an arm coupling mechanism 124 according to a fourth embodiment of the present invention. Although the hydraulic chamber 78 is provided on the high-lift arm 70 side in the arrangement shown in FIG. 3 , in the fourth embodiment, it is assumed that the hydraulic path 132 and the hydraulic chamber 134 are not provided On the side of the second rocking cam arm 126R. Assume further that the high-lift arm 130 side includes a pin hole 128 that accommodates a piston 136 and a return spring 138 . The arm coupling mechanism 124 according to the fourth embodiment of the present invention is characterized by the shape of the portion marked with "A" in the pin hole 128 in the high-lift arm 130 in FIG. 13 .

14A and 14B are enlarged views showing part A of FIG. 13 . More specifically, FIG. 14A is a view showing the pin hole 128 viewed from the hydraulic chamber 134 side. FIG. 14B is a view showing a cross-section of part A. FIG. 14A and 14B, at the entrance of the pin hole 128, a guide surface 128a for guiding the pin 76 is formed. The guide surface 128a is formed such that a larger concave radius is formed at a portion of the side (right side of FIG. 14B ) where the second rocking cam arm 126R moves into for the pin switching operation, thereby ensuring that the pin 76 is more easily Insert into pin hole 128. The guide surface 128 a is formed in a radial shape with a gradually increasing radius toward the entrance of the pin hole 128 . More specifically, the guide surface 128 a is formed such that the inclination angle with respect to the axis of the pin hole 128 becomes gradually smaller toward the entrance of the pin hole 128 . Even in the arrangement in which the hydraulic chamber 78 is provided on the large lift arm 70 side (the arrangement shown in FIG. 3 ), if a guide surface similar to the guide surface 128a is provided on the second rocking cam arm 40R side, similar These arrangements of the arm coupling mechanism 124 are realized in a perfect manner.

15A and 15B are views for illustrating a pin switching operation in the fourth embodiment of the present invention. FIG. 15A is a view showing a situation where the pin 76 is not axially aligned with the pin hole 128 . According to the arm coupling mechanism 124 of the fourth embodiment of the present invention, even when the pin 76 is not axially aligned with the pin hole 128, the pin 76 applied with hydraulic pressure can be guided to the guide surface 128a, which rotates the second rocking cam Arm 126R axially aligns pin 76 with pin hole 128 as shown in FIG. 15B. This allows the pin 76 to be inserted into the pin hole 128 .

FIG. 16 is a view for illustrating the operation of the second rocking cam arm 126R during the pin switching operation. FIG. 12 referred to above is related to the situation of FIG. 15A. According to the arm coupling mechanism 124 of the fourth embodiment of the present invention, even when the pin 76 is not axially aligned with the pin hole 128 as shown in FIG. 12 , the pin switching operation can be performed. FIG. 16 shows the case where the pin switching operation is completed due to the rotation of the second rocking cam arm 126R shown in FIG. 15B after the pin switching operation is attempted in the situation shown in FIG. 12 . Specifically, with such a pin switching operation, when the pin 76 is inserted into the pin hole 128, the second rocking cam arm 126R, which was in the same posture as the first rocking cam arm 40L before the start of the pin switching operation, rotates to the position shown in FIG. s position.

As previously stated, the arrangement in the fourth embodiment of the present invention does not require actuation of the control shaft 34 to move the second rocker cam arm 126R to an operational angular position in which the pin 76 is axially aligned with the pin hole 128 for performing pin operation. Toggle action. Specifically, when the single-valve variable control is required, the operation time for moving the second rocking cam arm 126R to the operation angle pose capable of the pin switching operation is reduced. In addition, according to the arrangement made in the fourth embodiment of the present invention, the second rocking cam arm 126R itself rotates to the position of the maximum operation angle causing the pin 76 to be coupled. This does not require setting the cam height of the second drive cam 122 to be greater than that of the first drive cam 12 as in the aforementioned first and second embodiments. However, it should be noted that in the arrangement made in the fourth embodiment of the present invention, the second drive cam 122 may also be provided with a cam height different from that of the first drive cam 12 .

In the arrangement of the arm coupling mechanism 124 described above, the guide surface 128 a is formed in a radial shape whose radius gradually increases toward the entrance of the pin hole 128 . Therefore, when the single-valve variable control is switched to the double-valve variable control, that is, when the pin 76 moves out of the pin hole 128, by the effect of the shape of the guide surface 128a shown in FIG. The speed at which the rocking cam arm 126R moves toward the small operation angle side can be gradually reduced. Therefore, when the second rocking cam arm 126R contacts the second roller 44 again after the coupling of the pin 76 is released, the contact can be relaxed, thereby contributing to reducing noise or shock load generated upon contact.

In the fourth embodiment of the present invention, the guide surface 128a in the pin hole 128 is formed radially. The shape of the guide surface according to the present invention is not limited to radial. For example, the guide surface may be chamfered into a plurality of steps such that the angle of inclination with respect to the axis of the pin hole becomes smaller towards the entrance of the pin hole.

The guide surface 128a according to the fourth embodiment of the present invention corresponds to the "guide surface" of the sixth aspect of the present invention.

Claims (8)

1. A variable valve device in which the control of the valve opening characteristic of at least one of the plurality of valves to be switched is changed from control in the variable control mode to control in the fixed control mode or from the fixed control mode The control of the valve is changed to the control under the variable control mode, the variable valve device includes: an oscillating member disposed between the main cam and the valve, the oscillating member transmitting the pressure of the main cam to the valve; a valve opening characteristic variable device for controlling the pose of the rocking member within a predetermined range to variably control the valve opening characteristic of the valve to be switched; valve opening characteristic fixing means for fixedly controlling the valve opening characteristic of the valve to be switched; and changing means for switching the control of the valve opening characteristic of the valve to be switched from the control in the variable control mode to the control in the fixed control mode or from the control in the fixed control mode switch to control in said variable control mode; Wherein the changing means is configured to allow the valve opening characteristic of the valve to be switched to be changed when the rocking member is in a posture related to an operating range in which switching of the valve opening characteristic of the valve to be switched is required. 2. The variable valve device according to claim 1, The operating range in which the valve opening characteristic of the valve to be switched needs to be switched includes a low engine speed range or a low load range for reducing NOx or improving fuel economy. 3. The variable valve device according to claim 1 or 2, wherein the valve opening characteristic variable device includes an intermediate member disposed between the main cam and the valve to be switched, and a control device for changing the position of the intermediate member; wherein said intermediate member is shared by said plurality of valves including said valve to be switched; including a second cam separate from the primary cam; Wherein the valve opening characteristic fixing device includes an input arm that shakes in phase with the rotation of the second cam; wherein said changing means engages or disengages the coupling between said rocker member for moving said valve to be switched and said input arm; Wherein the second cam is configured to have a greater cam height than the primary cam. 4. The variable valve device according to claim 3, Wherein the changing device is set so that, when the operating range of the valve opening characteristic of the valve to be switched needs to be switched within a predetermined range, when the rocking member is in the position to achieve the valve to be switched within the The valve opening characteristic of the valve to be switched can be switched in the case of the minimum operating angle and/or the minimum lift posture within the range. 5. The variable valve device according to claim 3, Wherein the changing device is set so that, when the operating range of the valve opening characteristic of the valve to be switched needs to be switched within a predetermined range, when the rocking member is in the position to achieve the valve to be switched within the The valve opening characteristic of the valve to be switched can be switched in the case of the maximum operating angle and/or maximum lift within the range. 6. The variable valve device according to claim 1 or 2, wherein the valve opening characteristic variable device includes an intermediate member disposed between the main cam and the valve to be switched, and a control device for changing the position of the intermediate member; wherein said intermediate member is shared by said plurality of valves including said valve to be switched; including a second cam separate from the primary cam; Wherein the valve opening characteristic fixing device includes an input arm that shakes in phase with the rotation of the second cam; wherein said changing means comprises a pin which engages or disengages the coupling of said pin between said rocking member for moving said valve to be switched and said input arm; wherein the rocking member or the input arm for moving the valve to be switched includes a pin hole into which the pin is inserted; and Wherein the entrance portion of the pin hole includes a guide surface formed to guide the pin inserted into or removed from the pin hole. 7. The variable valve device according to claim 6, Wherein the guide surface has an inclination angle relative to the axis of the pin hole, the inclination angle becoming smaller toward an entrance portion of the pin hole. 8. The variable valve device according to any one of claims 1 to 7, Wherein the profile of the second cam is set such that the phase of the valves to be switched achieved by the second cam is different from the phase of the valves achieved by the main cam.

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