JP2014084797A - Variable valve device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable valve device for an internal combustion engine, capable of actualizing an easy multi-stage variation of valve characteristics.SOLUTION: The variable valve device for an internal combustion engine includes a variable mechanism unit 300 for changing the valve characteristics of an intake valve 31, a control shaft 340 for operating the variable mechanism unit 300, a cam 530 for moving the control shaft 340 in the axial direction, an electric motor 210 for turning the cam 530, and a gear mechanism 220 for transmitting the driving force of the motor 210 to the cam 530. A lock mechanism 600 is provided for engaging with a second gear 222 of the gear mechanism 220 to restrict the turn of the second gear 222.

Description

  The present invention relates to a variable valve gear that changes the valve characteristics of an engine valve.

For example, as described in Patent Document 1, there is known a variable valve operating apparatus that changes valve characteristics of an engine valve such as an intake valve or an exhaust valve in accordance with an engine operating state.
The variable valve operating apparatus described in Patent Document 1 includes a variable mechanism section (intermediate drive mechanism in the same document) that changes the valve characteristics of an internal combustion engine, a control shaft that operates the variable mechanism section, and a control shaft in the axial direction. There are provided a ball-shaped cam to be moved, a motor for rotating the cam, and a reduction gear for transmitting the driving force of the motor to the cam. The valve characteristic is variably controlled by controlling the rotational phase of the cam.

  Here, an axial force (hereinafter referred to as an axial force) is applied to the control shaft due to the reaction force of the valve spring that biases the engine valve, and this axial force acts on the cam surface. A rotational moment is generated in the cam. Therefore, in a mechanism that uses a cam to move the control shaft, when the motor is stopped, the cam rotates and the valve characteristics change. In order to suppress such a change in valve characteristics, it is necessary to generate a force against the rotational moment from the motor. Therefore, when an electric motor is used as a motor for rotating the cam, it is necessary to supply a holding current to the motor in order to suppress a change in valve characteristics.

  Therefore, in the apparatus described in the document 1, as the cam profile, a section where the displacement amount of the control shaft changes and a section where the displacement amount becomes constant are provided. In other words, the cam surface is provided with a change area where the valve characteristic changes due to a change in the displacement amount of the control shaft, and a holding area where the valve characteristic remains constant and does not change. Yes.

  When using a cam surface in this holding area, that is, a cam surface having a constant distance from the rotation center of the cam, the generation of the rotational moment due to the axial force is suppressed. Is suppressed. Therefore, even if the motor is stopped, the valve characteristic is maintained at the valve characteristic corresponding to the holding region. Therefore, for example, the holding current as described above can be reduced.

JP 2004-339951 A

  By the way, if a plurality of holding regions are provided on the cam surface, a plurality of different valve characteristics can be held, and the valve characteristics can be changed in multiple stages.

  However, since the cam surface is limited, there is a limit to the number that can be set even if a plurality of holding areas are provided. Therefore, it is difficult to increase the number of variable stages of the valve characteristics in the aspect in which the valve characteristics are varied in multiple stages by forming a plurality of holding regions on the cam surface. Such a problem is not limited to the slanted cam described in Patent Document 1, and even cams having other shapes may have the same cam surface because of limited cam surfaces.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a variable valve operating apparatus for an internal combustion engine that can easily change the valve characteristics in multiple stages.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
A variable valve operating apparatus for an internal combustion engine that solves the above problems includes a variable mechanism that changes valve characteristics of the internal combustion engine, a control shaft that operates the variable mechanism, a cam that moves the control shaft in the axial direction, An internal combustion engine comprising: an electric motor that rotates the cam; and a gear mechanism that transmits a driving force of the electric motor to the cam, and performing variable control of the valve characteristics by controlling a rotation phase of the cam. The variable valve device includes a lock mechanism that engages with a gear of the gear mechanism and restricts rotation of the gear.

  In the above configuration, a gear mechanism that transmits the driving force of the motor to the cam is provided. And the locking mechanism which regulates rotation of the gear which a gear mechanism has is provided. When the rotation of the gear is restricted by the lock mechanism, the rotation of the cam is also restricted, so that the movement of the control shaft is also restricted. Therefore, the valve characteristic changed by the variable mechanism unit can be maintained at the valve characteristic at the time when the rotation of the gear is restricted by the lock mechanism. Therefore, for example, it is possible to reduce the holding current of the electric motor necessary for maintaining the valve characteristics.

  Further, by engaging the lock mechanism with the gear of the gear mechanism, the rotation of the gear is restricted. Therefore, the number of valve characteristics that can be held, that is, the number of variable stages of the valve characteristics depends on the number of gear teeth, and the valve characteristics can be easily varied in multiple stages.

In the variable valve operating apparatus, it is preferable that the lock mechanism is engaged with a gear having the largest radius among the gears constituting the gear mechanism. This is due to the following reason.
That is, the rotational force acting on the rotating shaft of the gear is “FS”, the radius of the gear (distance from the center of rotation to the tooth tip) is “R”, and the force acting in the tangential direction on the outer peripheral surface of the gear. A drag force (a force against the rotational force FS) necessary for restricting the rotation is “F1”. In this case, when the expression “FS = R × F1” is satisfied, the rotation of the gear is stopped by the drag F1. Here, as can be seen from the above formula, as the radius R increases, the rotation of the gear can be regulated with a smaller drag F1. Therefore, in this configuration, the lock mechanism is engaged with the gear having the largest radius among the gears constituting the gear mechanism. Therefore, the drag force F1 necessary for restricting the rotation of the gear can be made sufficiently small. As a result, for example, the load acting on the lock mechanism can be reduced when the rotation of the gear is restricted.

  Further, the gear having the largest radius among the gears constituting the gear mechanism is generally the gear having the largest number of teeth among the gears constituting the gear mechanism. Therefore, in this configuration, the lock mechanism is engaged with the gear having the largest number of teeth among the gears constituting the gear mechanism. Here, the greater the number of teeth of the gear engaged with the lock mechanism, the greater the number of variable stages of the valve characteristics. Therefore, according to the same configuration, it is possible to change the valve characteristics more finely and to improve the control accuracy when changing the valve characteristics, compared with the case where the lock mechanism is engaged with a gear having a small number of teeth. It becomes like this.

  In the variable valve operating apparatus, the gear mechanism is a reduction mechanism including a plurality of gears that reduce the rotation of the electric motor and transmit the rotation to the cam, and the lock mechanism is a gear included in the reduction mechanism. It is preferable to engage with a gear different from the gear provided on the rotating shaft of the cam.

  In the speed reduction mechanism, the gear reduction ratio increases as the distance from the electric motor toward the cam increases. Therefore, the force acting in the tangential direction on the outer peripheral surface of the gear and acting in the rotational direction of the gear becomes larger as the gear is closer to the cam. Accordingly, the drag force F1 necessary for restricting the rotation of the gear becomes larger as the gear is closer to the cam, and among the gears provided in the speed reduction mechanism, the drag force F1 at the gear provided on the rotating shaft of the cam is the largest. Become. Therefore, in this configuration, the lock mechanism is engaged with a gear different from the gear provided on the rotation shaft of the cam among the gears included in the speed reduction mechanism, that is, the gear different from the gear having the largest drag force F1. Yes. Therefore, it becomes possible to suppress the largest drag F1 from acting on the lock mechanism. For example, compared with the case where the lock mechanism is engaged with the gear provided on the rotating shaft of the cam, the lock mechanism The acting load can be reduced.

  As described above, the drag F1 increases as the gear is closer to the cam, and conversely, the drag F1 decreases as the gear is closer to the electric motor. Among the gears included in the speed reduction mechanism, the rotation shaft of the electric motor is reduced. The drag force F1 at the gear provided in is minimized. Therefore, in terms of reducing the load acting on the lock mechanism, the “gear different from the gear provided on the rotating shaft of the cam”, that is, the gear that engages the lock mechanism in the same configuration, is connected to the electric motor as much as possible. It is preferable that the gears be close to each other. If possible, the load acting on the lock mechanism can be reduced as much as possible by engaging the lock mechanism with a gear provided on the rotating shaft of the electric motor.

  In the variable valve apparatus, it is preferable that the lock mechanism includes an engagement member that engages with the gear, and an electromagnetic actuator that engages and disengages the engagement member and the gear.

  Furthermore, in the variable valve operating apparatus, it is preferable that the engagement between the engagement member and the gear is released when the electromagnetic actuator is in an energized state. According to the same configuration, by energizing the electromagnetic actuator and the electric motor, the gears can be rotated, and the energization state of the electromagnetic actuator and the electric motor when changing the valve characteristics is made the same. be able to.

  In the variable valve operating apparatus, it is preferable that the engagement member is an arm having a tip portion that engages with the gear, and the electromagnetic actuator is an electromagnet that attracts the arm.

  In the variable valve operating apparatus, it is preferable that the electromagnetic actuator is an electromagnetic solenoid that allows a plunger to enter and exit, and the plunger is used as the engaging member.

Sectional drawing which shows the structure around the cylinder head of the engine with which one Embodiment of a variable valve apparatus is applied. The fracture | rupture perspective view of a variable mechanism part. The schematic diagram of a variable valve apparatus. The figure which shows a cam profile. (A) is a schematic diagram showing the operating state of the lock mechanism when the valve characteristic is maintained, (B) is a schematic diagram showing the operating state of the lock mechanism when changing the valve characteristic. The schematic diagram which shows the force which acts on a gearwheel. The schematic diagram of the locking mechanism in the modification of the embodiment.

Hereinafter, an embodiment of a variable valve operating apparatus for an internal combustion engine will be described with reference to FIGS.
As shown in FIG. 1, the internal combustion engine 1 includes a cylinder block 10 and a cylinder head 20 placed above the cylinder block 10.

  A cylindrical cylinder 11 corresponding to the number of cylinders is formed inside the cylinder block 10, and a piston 12 is slidably accommodated in each cylinder 11. A cylinder head 20 is assembled to the upper part of the cylinder block 10, and a combustion chamber 13 is defined by an inner peripheral surface of the cylinder 11, an upper surface of the piston 12, and a lower surface of the cylinder head 20.

  An intake port 21 and an exhaust port 22 communicating with the combustion chamber 13 are formed in the cylinder head 20. The intake port 21 constitutes a part of the intake passage 30. Further, the exhaust port 22 constitutes a part of the exhaust passage 40.

  The intake port 21 is provided with an intake valve 31 as an engine valve that communicates and blocks the combustion chamber 13 and the intake port 21. The exhaust port 22 is provided with an exhaust valve 41 as an engine valve that communicates and blocks the combustion chamber 13 and the exhaust port 22. The valves 31 and 41 are biased in the valve closing direction by the valve spring 24.

  A lash adjuster 25 is provided in the cylinder head 20 corresponding to the valves 31 and 41. A rocker arm 26 is installed between the lash adjuster 25 and the valves 31 and 41. One end of the rocker arm 26 is supported by the lash adjuster 25, and the other end is in contact with the end portions of the valves 31 and 41.

  Further, an intake camshaft 32 and an exhaust camshaft 42 that drive the valves 31, 41 are rotatably supported by the cylinder head 20, respectively. An intake cam 32 a is formed on the intake cam shaft 32, and an exhaust cam 42 a is formed on the exhaust cam shaft 42. The outer peripheral surface of the exhaust cam 42 a is in contact with the roller 26 a of the rocker arm 26 that is in contact with the exhaust valve 41. Thus, when the exhaust camshaft 42 rotates during engine operation, the rocker arm 26 swings about the portion supported by the lash adjuster 25 by the action of the exhaust cam 42a. As the rocker arm 26 swings, the exhaust valve 41 is lifted in the valve opening direction.

  On the other hand, a variable mechanism 300 that changes the valve characteristics of the intake valve 31 is provided for each cylinder between the rocker arm 26 that contacts the intake valve 31 and the intake cam 32a. The variable mechanism unit 300 is a mechanism that constitutes a part of the variable valve operating apparatus, and includes an input arm 311 and an output arm 321. The input arm 311 and the output arm 321 are swingably supported around a support pipe 330 fixed to the cylinder head 20. The rocker arm 26 is urged toward the output arm 321 by the urging force of the valve spring 24, and a roller 26 a provided at an intermediate portion of the rocker arm 26 is in contact with the outer peripheral surface of the output arm 321.

  Further, a protrusion 313 is provided on the outer peripheral surface of the variable mechanism portion 300, and a biasing force of a spring 50 fixed in the cylinder head 20 acts on the protrusion 313. Due to the urging force of the spring 50, the roller 311a provided at the tip of the input arm 311 is in contact with the outer peripheral surface of the intake cam 32a. As a result, when the intake camshaft 32 rotates during engine operation, the variable mechanism portion 300 swings around the support pipe 330 by the action of the intake cam 32a. Then, when the rocker arm 26 is pressed by the output arm 321, the rocker arm 26 swings around the portion supported by the lash adjuster 25. The rocking of the rocker arm 26 lifts the intake valve 31 in the valve opening direction.

  A control shaft 340 that is movable along the axial direction is inserted into the support pipe 330. The variable mechanism 300 changes the relative phase difference between the input arm 311 and the output arm 321 around the support pipe 330, that is, the angle θ shown in FIG. 1 by displacing the control shaft 340 in the axial direction.

Next, the configuration of the variable mechanism unit 300 will be described in more detail with reference to FIG.
As shown in FIG. 2, the variable mechanism unit 300 is provided with output units 320 on both sides of the input unit 310.

The housings 314 and 323 of the input unit 310 and the output unit 320 are each formed in a hollow cylindrical shape, and a support pipe 330 is inserted through them.
A helical spline 312 is formed on the inner periphery of the housing 314 of the input unit 310. On the other hand, on the inner periphery of the housing 323 of each output unit 320, a helical spline 322 whose tooth traces are opposite to the helical spline 312 of the input unit 310 is formed.

  A slider gear 350 is disposed in a series of internal spaces formed by the housings 314 and 323 of the input unit 310 and the two output units 320. The slider gear 350 is formed in a hollow cylindrical shape, and is disposed on the outer peripheral surface of the support pipe 330 so as to be able to reciprocate in the axial direction of the support pipe 330 and to be relatively rotatable around the axis of the support pipe 330. ing.

  A helical spline 351 that meshes with the helical spline 312 of the input unit 310 is formed on the outer peripheral surface of the slider gear 350 in the axial center. On the other hand, helical splines 352 that mesh with the helical splines 322 of the output unit 320 are formed on the outer peripheral surfaces of both ends in the axial direction of the slider gear 350.

  A control shaft 340 that is movable in the axial direction of the support pipe 330 is provided inside the support pipe 330. The control shaft 340 and the slider gear 350 are engaged by pins, the slider gear 350 can rotate with respect to the support pipe 330, and the slider gear 350 also moves in the axial direction in accordance with the movement of the control shaft 340 in the axial direction. To do.

  In the variable mechanism section 300 configured as described above, when the control shaft 340 moves in the axial direction, the slider gear 350 also moves in the axial direction in conjunction with the movement of the control shaft 340. Helical splines 351 and 352 formed on the outer peripheral surface of the slider gear 350 have different tooth trace formation directions, respectively, and helical splines 312 and 322 formed on the inner peripheral surfaces of the input unit 310 and the output unit 320, respectively. Meshed. Therefore, when the slider gear 350 moves in the axial direction, the input unit 310 and the output unit 320 rotate in opposite directions. As a result, the relative phase difference between the input arm 311 and the output arm 321 is changed, and the maximum lift amount and the valve opening period that are valve characteristics of the intake valve 31 are changed. Specifically, when the control shaft 340 is moved in the arrow Hi direction shown in FIG. 2, the slider gear 350 is moved in the arrow Hi direction together with the control shaft 340. Accordingly, the relative phase difference between the input arm 311 and the output arm 321, that is, the angle θ shown in FIG. 1 increases, and the maximum lift amount VL and the valve opening period INCAM of the intake valve 31 increase to increase the intake air amount. Increase. On the other hand, when the control shaft 340 is moved in the direction of the arrow Lo shown in FIG. 2, the relative phase difference between the input arm 311 and the output arm 321 becomes smaller as the slider gear 350 moves in the direction of the arrow Lo together with the control shaft 340. . As a result, the maximum lift amount VL and the valve opening period INCAM of the intake valve 31 are reduced, and the intake air amount is reduced.

Next, the configuration of the drive unit that moves the control shaft 340 in the axial direction will be described.
As shown in FIG. 3, the drive unit includes an electric motor 210, a gear mechanism 220 that reduces the rotational speed of the motor 210, a conversion mechanism 500 that converts the rotational movement of the gear into a linear movement of the control shaft 340, and the like. ing.

The motor 210 is connected to the motor control device 150, and the rotation angle and the rotation speed are controlled according to the drive signal from the motor control device 150.
The gear mechanism 220 includes a first gear 221 provided on the rotation shaft of the motor 210, a second gear 222 meshing with the first gear, a third gear 223 provided on the rotation shaft of the second gear 222, and a third gear 223. It is comprised with the 4th gearwheel 224 which meshes with.

  The first gear 221 and the second gear 222 are a first-stage gear pair, and the third gear 223 and the fourth gear 224 are a second-stage gear pair. Then, assuming that the number of teeth of the first gear 221 is Z1, the number of teeth of the second gear 222 is Z2, the number of teeth of the third gear 223 is Z3, and the number of teeth of the fourth gear 224 is Z4, Z2> Z1 ”and“ Z4> Z3 ”. The gear mechanism 220 is a mechanism that decelerates the rotational speed of the motor 210 due to the magnitude relationship of the number of teeth, and the reduction ratio thereof is “(Z2 / Z1) × (Z4 / Z3)”.

Of the first gear 221 to the fourth gear 224, the second gear 222 is the gear having the largest number of teeth and the largest radius (distance from the rotation center of the gear to the tooth tip).
The conversion mechanism 500 includes a holder 510 that reciprocates along the guide 520. The holder 510 is provided with a connecting shaft 511 extending toward the control shaft 340, and the connecting shaft 511 and the control shaft 340 are connected by a connecting member 400. A cam 530 is provided inside the holder 510. The fourth gear 224 is provided on the rotation shaft of the cam 530, and the cam 530 rotates in synchronization with the rotation of the fourth gear 224. The holder 510 is rotatably provided with a roller 540 that contacts the cam surface of the cam 530. When the cam 530 rotates, the holder 510 that is a driven node (a member to which the cam motion is transmitted) is displaced.

  As shown in FIG. 4, the cam 530 has a cam profile in which the displacement amount of the holder 510 increases linearly as the rotation angle increases, and is a slanted cam with a gradually increasing radius. ing.

  Here, since the reaction force from the valve spring 24 acts on the output portion 320 of the variable mechanism portion 300, a force for reducing the relative phase difference between the input arm 311 and the output arm 321 is applied. Accordingly, an axial force acts on the slider gear 350 and the control shaft 340 in the direction in which the maximum lift amount VL decreases (in the direction of the arrow Lo shown in FIG. 3). When an axial force acts on the control shaft 340 in this way, a similar axial force also acts on the holder 510 via the connecting member 400 and the connecting shaft 511, and the roller 540 and the cam 530 are in contact with each other by this axial force. Maintained.

  In the drive unit configured as described above, the control shaft 340 moves in the axial direction as the cam 530 rotates. For example, as shown in FIG. 3, when the cam 530 rotates in the direction of arrow H and the roller 540 of the holder 510 contacts the cam surface having the largest radius in the cam 530, the control shaft 340 is moved to the arrow shown in FIG. 3. Move to the maximum movement position in the Hi direction. As a result, the maximum lift amount VL and the valve opening period INCAM of the intake valve 31 are maximized.

  On the other hand, as shown in FIG. 3, when the cam 530 rotates in the direction of the arrow L and the roller 540 of the holder 510 contacts the cam surface having the smallest radius in the cam 530, the control shaft 340 moves to the arrow shown in FIG. Move to the maximum position in the Lo direction. As a result, the maximum lift amount VL and the valve opening period INCAM of the intake valve 31 are minimized.

In this way, the valve characteristics are variably controlled by rotating the cam 530 and controlling its rotational phase.
Further, in the vicinity of the gear mechanism 220, a lock mechanism 600 that engages with the second gear 222 having the largest radius among the gears constituting the gear mechanism 220 and restricts the rotation of the second gear 222 is provided. It has been.

  The lock mechanism 600 is provided with an arm 610 as an engagement member that engages with a gear. The arm 610 is made of a rod-like magnetic body (for example, iron subjected to rust prevention treatment, etc.), and is supported so as to be swingable about a rotation shaft 620 provided near the center of the arm 610. ing.

The tip 610 a of the arm 610 is bent, and the tip 610 a engages with the teeth of the second gear 222.
In the arm 610, a spring 630 that urges the tip 610a toward the tooth bottom of the second gear 222 is provided at an end (hereinafter referred to as a terminal) 610b opposite to the tip 610a. Further, an electromagnet 640 serving as an electromagnetic actuator that attracts the end portion 610b against the biasing force of the spring 630 is provided in the vicinity of the end portion 610b. The electromagnet 640 is connected to the motor control device 150, and the energization state and the non-energization state of the electromagnet 640 are controlled by the motor control device 150.

  As shown in FIG. 5A, when the electromagnet 640 is in a non-energized state, the tip 610 a of the arm 610 is engaged with the teeth of the second gear 222 by the biasing force of the spring 630. As a result, the arm 610 and the second gear 222 are engaged. On the other hand, as shown in FIG. 5B, when the electromagnet 640 is energized, the distal end portion 610b of the arm 610 is attracted, so that the arm 610 moves in a direction in which the distal end portion 610a moves away from the teeth of the second gear 222. Thus, the engagement between the arm 610 and the second gear 222 is released.

By switching between energization and non-energization of the electromagnet 640 in this manner, the arm 610 and the second gear 222 are engaged and disengaged.
Various controls of the internal combustion engine 1 are performed by the engine control device 100. Various sensors are connected to the engine control apparatus 100. For example, the engine control apparatus 100 includes an accelerator sensor 111 that detects an accelerator pedal operation amount (accelerator operation amount ACCP), and an opening degree of a throttle valve (throttle opening TA) provided in the intake passage 30 of the internal combustion engine 1. ) Is connected to the throttle sensor 112. Further, the engine control device 100 determines the amount of air sucked into the combustion chamber 13 through the intake passage 30, that is, the air flow meter 113 for detecting the intake air amount GA, and the rotation angle of the crankshaft of the internal combustion engine 1. A crank angle sensor 114 and the like for detection are also connected. The engine control device 100 and the motor control device 150 are connected by a communication line and communicate with each other.

  The engine control apparatus 100 grasps the engine operating state based on signals output from the various sensors. Then, various engine controls such as fuel injection control and ignition timing control are performed based on the grasped engine operating state.

  Further, the engine control device 100 variably controls the valve characteristic of the intake valve 31 through communication with the motor control device 150. That is, the engine control apparatus 100 calculates a target lift amount VLp that is a target value of the maximum lift amount VL based on the engine operating state. The target lift amount VLp is input to the motor control device 150 via a communication line. The motor control device 150 controls the rotational phase of the cam 530 so that the target lift amount VLp matches the actual maximum lift amount VL.

Next, the operation obtained by the variable valve operating apparatus having the above configuration will be described.
As shown in FIG. 5A, when the electromagnet 640 is turned off by the motor control device 150, the arm 610 and the second gear 222 are engaged. By this engagement, the rotation of the second gear 222 is restricted, and thereby the rotation of the cam 530 is also restricted. When the rotation of the cam 530 is restricted in this way, the movement of the control shaft 340 due to the axial force is also restricted. Therefore, the maximum lift amount VL of the intake valve 31 is set by the lock mechanism 600 by the second gear 222. Is held at the maximum lift amount VL at the time when the rotation is restricted. Thus, when the electromagnet 640 is in a non-energized state, the valve characteristic is held at a constant value.

  In addition, by restricting the rotation of the second gear 222 by the lock mechanism 600, the valve characteristic of the intake valve 31 is maintained at a constant value. Therefore, the valve characteristic of the intake valve 31 can be held at a constant value without supplying a holding current to the motor 210. Therefore, when the rotation of the second gear 222 is restricted by the lock mechanism 600, that is, when the energization of the electromagnet 640 is stopped, the energization of the motor 210 is stopped.

  On the other hand, as shown in FIG. 5B, when the electromagnet 640 is energized by the motor control device 150, the engagement between the arm 610 and the second gear 222 is released. By releasing the engagement, each gear of the gear mechanism 220 can be turned. Therefore, by energizing the motor 210, the maximum lift amount VL of the intake valve 31 can be changed.

  Therefore, the maximum lift amount VL of the intake valve 31 is changed by energizing the electromagnet 640 and the motor 210. When the change of the maximum lift amount VL is completed, the energization to the electromagnet 640 is stopped and the rotation of the second gear 222 is restricted, so that the changed maximum lift amount VL is maintained and the motor 210 is changed. Stop energizing the.

  Here, by engaging the lock mechanism 600 with the teeth of the second gear 222, the rotation of the second gear 222 is restricted, and the maximum lift amount VL of the intake valve 31 is held at a constant value. Therefore, the number of maximum lift amounts VL that can be held, that is, the number of variable steps of the maximum lift amount VL is the number of steps according to the number of teeth of the second gear 222, and the teeth of the second gear 222 with which the arm 610 is engaged are different. By doing so, the maximum lift amount VL that can be retained can be changed in multiple stages.

Note that the number of variable stages of the maximum lift amount VL can be easily increased by increasing the number of teeth of the second gear 222.
The lock mechanism 600 is configured to engage with the second gear 222 having the largest radius among the gears constituting the gear mechanism 220. As a result, the following effects are obtained.

  FIG. 6 shows a general gear. As shown in FIG. 6, the rotational force acting on the rotating shaft 810 of the gear 800 is “FS”, the radius of the gear 800 (distance from the center of rotation to the tooth tip) is “R”, and the tangential direction on the outer peripheral surface of the gear 800 A force acting on the force and a force necessary to restrict the rotation of the gear (a force against the rotational force FS) is defined as “F1”. In this case, when the expression “FS = R × F1” holds, the rotation of the gear 800 is stopped by the drag F1. Here, as can be seen from the expression “FS = R × F1”, as the radius R increases, the rotation of the gear 800 can be regulated with a smaller drag F1. Therefore, in this embodiment, the lock mechanism 600 is engaged with the second gear 222 having the largest radius among the gears constituting the gear mechanism 220. Therefore, the drag force F1 necessary for restricting the rotation of the second gear 222 can be made sufficiently small. As a result, for example, the load acting on the lock mechanism 600 when the rotation of the second gear 222 is restricted can be reduced.

  Further, the gear having the largest radius among the gears constituting the gear mechanism is generally the gear having the largest number of teeth among the gears constituting the gear mechanism. Therefore, in this embodiment, the lock mechanism 600 is engaged with the second gear 222 having the largest number of teeth among the gears constituting the gear mechanism 220. Here, as the number of gear teeth with which the lock mechanism 600 is engaged increases, the number of variable stages of the valve characteristic (maximum lift amount VL) increases. Therefore, according to the present embodiment, it is possible to change the valve characteristics more finely than in the case where the lock mechanism 600 is engaged with a gear having a small number of teeth, and the control accuracy when changing the valve characteristics is also improved. improves.

  The lock mechanism 600 includes an arm 610 that engages with the second gear 222, and an electromagnet 640 that engages and disengages the arm 610 and the second gear 222. The electromagnet 640 is in an energized state. Sometimes, the engagement between the arm 610 and the second gear 222 is released. Therefore, by energizing the electromagnet 640 and the motor 210, the second gear 222 can be rotated, and the energization state of the electromagnet 640 and the motor 210 when changing the valve characteristics is made the same. Can do.

  By the way, as in the above-mentioned prior art, the change area where the valve characteristic changes due to the change in the displacement amount of the control shaft, and the hold where the displacement amount of the control shaft remains constant and the valve characteristic remains constant. When the area is provided on the cam surface, the following inconvenience may occur. That is, in the prior art, a holder that is a follower node of the cam surface and the end of the control shaft is provided, and a roller provided on the holder and the cam surface come into contact with each other. Here, if the cam rotation center deviates from the roller rotation center, or if the cam swings due to vibration, the cam tends to rotate from the holding area to the change area, so it is held at a constant value. There is a possibility that the valve characteristics that have been changed. In this regard, in the variable valve operating apparatus according to the present embodiment, the rotation of the second gear 222 is restricted by the lock mechanism 600 so that the valve characteristic is maintained at a constant value. Therefore, even if the rotation center of the cam 530 is deviated from the rotation center of the roller 540 or vibration is transmitted to the cam 530, the state of the second gear 222 can be maintained in a state where the rotation is restricted. It is possible to keep the valve characteristic at a constant value.

As described above, according to the present embodiment, the following effects can be obtained.
(1) The variable mechanism 300 that changes the valve characteristics of the intake valve 31 and the gear mechanism 220 that transmits the driving force of the motor 210 to the cam 530 are provided, and the intake valve is controlled by controlling the rotational phase of the cam 530. The valve characteristics of 31 are variably controlled. A lock mechanism 600 that engages with the second gear 222 of the gear mechanism 220 and restricts the rotation of the second gear 222 is provided.

  Therefore, the valve characteristic changed by the variable mechanism unit 300 can be maintained at the valve characteristic at the time when the rotation of the second gear 222 is restricted by the lock mechanism 600. Therefore, for example, it is possible to reduce the holding current of the motor 210 necessary for maintaining the valve characteristics of the intake valve 31.

  Further, since the number of valve characteristics that can be held, that is, the number of variable stages of the valve characteristics, depends on the number of teeth of the second gear 222, the valve characteristics of the intake valve 31 can be easily varied in multiple stages. Become.

  (2) The lock mechanism 600 is engaged with the second gear 222 having the largest radius among the gears constituting the gear mechanism 220. Therefore, the drag force F1 necessary for restricting the rotation of the second gear 222 can be made sufficiently small. As a result, for example, the load acting on the lock mechanism 600 when the rotation of the second gear 222 is restricted can be reduced. Further, the lock mechanism 600 is engaged with the second gear 222 having the largest number of teeth among the gears constituting the gear mechanism 220. Therefore, compared with the case where the lock mechanism 600 is engaged with a gear having a smaller number of teeth, the valve characteristic of the intake valve 31 can be finely changed, and the control accuracy when changing the valve characteristic is improved. To come.

  (3) When the electromagnet 640 is energized, the engagement between the arm 610 that engages the second gear 222 and the second gear 222 is released. Therefore, by energizing the electromagnet 640 and the motor 210, the second gear 222 can be rotated, and the energization state of the electromagnet 640 and the motor 210 when changing the valve characteristics is made the same. Can do.

In addition, the said embodiment can also be changed and implemented as follows.
Although the lock mechanism 600 is engaged with the second gear 222, it may be engaged with another gear. Even in this case, effects other than the above (2) can be obtained.

  The structure of the gear mechanism 220 can be changed as appropriate. Here, the gear mechanism 220 is a reduction mechanism that includes a plurality of gears that reduce the rotation of the electric motor 210 and transmit it to the cam 530. In such a reduction mechanism, the reduction ratio of the gear increases as it moves from the motor 210 to the cam 530. Therefore, the force acting in the tangential direction on the outer peripheral surface of the gear and acting in the rotational direction of the gear (the force acting in the opposite direction of the drag F1) increases as the gear is closer to the cam 530. Therefore, the drag F1 necessary for restricting the rotation of the gear becomes larger as the gear is closer to the cam 530, and among the gears provided in the speed reduction mechanism, the drag F1 at the gear provided on the rotation shaft of the cam 530 is the drag F1. Become the largest. Therefore, the lock mechanism 600 may be engaged with a gear different from a gear provided on the rotation shaft of the cam 530, that is, a gear different from the gear having the largest drag force F1 among the gears provided in the reduction mechanism. In this case, it becomes possible to suppress the largest drag F1 from acting on the lock mechanism 600, and for example, compared with a case where the lock mechanism 600 is engaged with a gear provided on the rotation shaft of the cam 530. Thus, the load acting on the lock mechanism 600 can be reduced.

  As described above, the drag F1 increases as the gear is closer to the cam 530. Conversely, the drag F1 decreases as the gear is closer to the motor 210, and the rotation of the motor 210 among the gears included in the reduction mechanism. Drag F1 at the gear provided on the shaft is the smallest. Therefore, in terms of reducing the load acting on the lock mechanism 600, the “gear different from the gear provided on the rotation shaft of the cam 530”, that is, the gear that engages the lock mechanism 600 is applied to the motor 210 as much as possible. It is preferable to use a close gear. If possible, if the lock mechanism 600 is engaged with a gear provided on the rotation shaft of the motor 210, the load acting on the lock mechanism 600 can be reduced as much as possible.

  The engagement between the arm 610 and the second gear 222 is released when the electromagnet 640 is energized, but the relationship between the arm 610 and the second gear 222 when the electromagnet 640 is deenergized. The structure of the lock mechanism 600 may be changed so that the match is released. In this modification, for example, instead of the spring 630, a spring that biases the tip 610a of the arm 610 in a direction away from the teeth of the second gear 222 is provided. Then, the electromagnet 640 can be realized at a position where the tip 610a of the arm 610 can be attracted. Even in this modification, effects other than the above (3) can be obtained.

  The lock mechanism 600 is configured by the arm 610, the electromagnet 640, or the like, but other configurations may be used to engage the gear of the gear mechanism 220 and restrict the rotation of the gear. . One such example is shown in FIG.

  As shown in FIG. 7, instead of the electromagnet 640, an electromagnetic solenoid 700 that allows the plunger (movable iron core) 710 to enter and exit is provided, and the energization state of the electromagnetic solenoid 700 is controlled by the motor control device 150. The plunger 710 is used as an engaging member that engages with the teeth of the second gear 222. In this modified example, when the electromagnetic solenoid 700 is used to project the plunger 710 when the energization is stopped while pulling the plunger 710 during the energization, the plunger 710 is projected by stopping the energization of the electromagnetic solenoid 700. The plunger 710 is engaged with the teeth of the second gear 222. On the other hand, by energizing the electromagnetic solenoid 700, the plunger 710 is retracted and the engagement between the plunger 710 and the second gear 222 is released, as shown by a two-dot chain line in FIG. Even in such a modification, it is possible to obtain the operational effects according to the above-described embodiment. Note that an electromagnetic solenoid that pulls the plunger 710 when energization is stopped while allowing the plunger 710 to project when energization may be used.

  -When the lock mechanism 600 restricts the rotation of the gear, the power supply to the motor 210 is stopped. In addition, when the rotation of the gear is restricted by the lock mechanism 600, a holding current for holding the valve characteristics is supplied to the motor 210, and thereby, for example, an engagement load that acts on the lock mechanism 600. You may make it suppress. Even in this case, since the rotation of the gear is restricted by the lock mechanism 600, a part of the rotational moment generated in the cam 530 is received by the lock mechanism 600. Therefore, when maintaining the valve characteristics, the holding current supplied to the motor 210 can be reduced as compared with the case where the rotation of the gear is not restricted by the lock mechanism 600.

The cam 530 is a slanting cam, but may be any other shape as long as the cam moves the control shaft in the axial direction.
The variable mechanism unit 300 is a mechanism that can change the maximum lift amount and the valve opening period of the intake valve 31. In addition, the present invention can be similarly applied to a mechanism that can change only the maximum lift amount or a mechanism that can change only the valve opening period. Further, a variable mechanism that changes valve characteristics (for example, valve opening timing, valve closing timing, etc.) different from the maximum lift amount and the valve opening period may be used. A variable mechanism that changes the valve characteristics of the exhaust valve 41 may be used.

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 10 ... Cylinder block, 11 ... Cylinder, 12 ... Piston, 13 ... Combustion chamber, 20 ... Cylinder head, 21 ... Intake port, 22 ... Exhaust port, 24 ... Valve spring, 25 ... Rush adjuster, 26 ... Rocker arm, 26a ... roller, 30 ... intake passage, 31 ... intake valve, 32 ... intake camshaft, 32a ... intake cam, 40 ... exhaust passage, 41 ... exhaust valve, 42 ... exhaust camshaft, 42a ... exhaust cam, 50 ... Spring, 100 ... engine control device, 111 ... accelerator sensor, 112 ... throttle sensor, 113 ... air flow meter, 114 ... crank angle sensor, 150 ... motor control device, 210 ... motor, 220 ... gear mechanism, 221 ... first Gears 222 ... second gear 223 ... third gear 224 ... fourth gear 300 ... variable Structure part, 310 ... input part, 311 ... input arm, 311a ... roller, 312 ... helical spline, 313 ... protrusion, 314 ... housing, 320 ... output part, 321 ... output arm, 322 ... helical spline, 323 ... housing, 330 DESCRIPTION OF SYMBOLS ... Support pipe, 340 ... Control shaft, 350 ... Slider gear, 351 ... Helical spline, 352 ... Helical spline, 400 ... Connecting member, 500 ... Conversion mechanism, 510 ... Holder, 511 ... Connection shaft, 520 ... Guide, 530 ... Cam, 540 ... Roller, 600 ... Lock mechanism, 610 ... Arm, 610a ... Tip, 610b ... End, 620 ... Rotating shaft, 630 ... Spring, 640 ... Electromagnet, 700 ... Electromagnetic solenoid, 710 ... Plunger, 800 ... Gear, 810 ... A rotating shaft.

Claims (7)

A variable mechanism section that changes a valve characteristic of the internal combustion engine, a control shaft that operates the variable mechanism section, a cam that moves the control shaft in an axial direction, an electric motor that rotates the cam, and an electric motor A variable valve operating apparatus for an internal combustion engine that includes a gear mechanism that transmits a driving force to the cam, and performs variable control of the valve characteristics by controlling a rotation phase of the cam.
A variable valve operating apparatus for an internal combustion engine, comprising: a lock mechanism that engages with a gear of the gear mechanism to restrict rotation of the gear. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the lock mechanism is engaged with a gear having the largest radius among the gears constituting the gear mechanism. The gear mechanism is a reduction mechanism that includes a plurality of gears that reduce the rotation of the electric motor and transmit the rotation to the cam.
The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the lock mechanism is engaged with a gear different from a gear provided on a rotation shaft of the cam among gears provided in the speed reduction mechanism. The lock mechanism includes an engagement member that engages with the gear, and an electromagnetic actuator that engages and disengages the engagement member and the gear. The variable valve operating apparatus for an internal combustion engine. The variable valve operating apparatus for an internal combustion engine according to claim 4, wherein when the electromagnetic actuator is energized, the engagement between the engagement member and the gear is released. 6. The variable valve operating apparatus for an internal combustion engine according to claim 4, wherein the engagement member is an arm having a tip end portion that engages with the gear, and the electromagnetic actuator is an electromagnet that attracts the arm. The variable valve operating apparatus for an internal combustion engine according to claim 4 or 5, wherein the electromagnetic actuator is an electromagnetic solenoid that allows a plunger to enter and exit, and uses the plunger as the engagement member.