JP2005325786A - Valve opening and closing property control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve opening and closing property control device for an internal combustion engine capable of reducing energy required for driving the device as much as possible and of improving response in changing the opening and closing property of a valve of the internal combustion engine. <P>SOLUTION: Variable mechanisms 50 are for changing the opening and closing property of the intake valves opened and closed by a plurality of air suction intake cams 22 formed on an intake camshaft 21 of the gasoline engine 10. The variable mechanisms 50 provided correspondingly to the intake valves can be independently driven respectively, and are controlled by ECU (Electronic Control Unit) 70 independently. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a valve opening / closing characteristic control device for an internal combustion engine capable of controlling the opening / closing characteristics of valves such as an intake valve and an exhaust valve of the internal combustion engine.

As such an apparatus, for example, the one shown in Patent Document 1 is known. In this configuration, a variable mechanism including a rocker arm or the like that transmits a valve driving force from a cam provided on the cam shaft to a valve such as an intake valve or an exhaust valve is provided. In this mechanism, the maximum lift amount of the engine valve is changed by switching the amplitude of the rocker arm based on the operating state of the engine. This mechanism is provided for each cylinder of the engine, and all of these mechanisms are driven based on the hydraulic pressure supplied from the same pressure source to adjust the maximum lift amount (see Patent Document 1). .
JP-A-1-257708

  In the above configuration, a part of the hydraulic pressure supply path from the pressure source to each mechanism is shared by each mechanism, and the mechanism is supplied to drive each mechanism by an actuator including an electromagnetic valve provided in the shared portion. The maximum lift is adjusted by controlling the hydraulic pressure. However, in a mode in which all of the plurality of variable mechanisms are driven based on the hydraulic pressure supplied from the same actuator, all the mechanisms are uniformly driven based on the hydraulic pressure.

  Therefore, even if there is an optimum period for changing the maximum lift amount for only one mechanism, all the other mechanisms are driven together during the same period. Therefore, for other mechanisms, an increase in driving energy, and hence a decrease in driving response, cannot be avoided.

  The present invention has been made in view of such circumstances, and an object of the present invention is to reduce the energy required for driving the internal combustion engine when changing its opening / closing characteristics as much as possible, and to improve the responsiveness. An object of the present invention is to provide an engine valve opening / closing characteristic control device.

In the following, means for achieving the above object and its effects are described.
First, the invention according to claim 1 corresponds to the valve in the valve opening / closing characteristic control device for the internal combustion engine that changes the opening / closing characteristic of the valve opened / closed by a plurality of cams formed on the camshaft of the internal combustion engine through a variable mechanism. The gist of the present invention is that each of the variable mechanisms is configured to be independently drivable, and includes control means for controlling the variable mechanisms.

  In the above-described configuration, each variable mechanism can be controlled separately, so that the change timing of the opening / closing characteristics of the valve can be set individually for each variable mechanism. Therefore, when changing the opening / closing characteristics of each valve, for example, each change time is set in a period in which the valve driving force by the cam and the reaction force acting on each variable mechanism are reduced based on this. It is possible to reduce energy consumption in the mechanism and to improve responsiveness when changing the valve opening / closing characteristics.

  Further, in such an aspect in which each variable mechanism can be controlled individually, for example, when performing so-called cylinder stop in which fuel supply is stopped in some cylinders, the pumping loss of the valve opening / closing characteristics only for that cylinder is reduced. Thus, the fuel consumption can be reduced.

  The valve opening / closing characteristics include, for example, the valve lift timing and the valve closing timing, in addition to the valve maximum lift amount and the change in lift amount between the minimum lift position and the maximum lift position.

  Incidentally, in a configuration in which each cylinder of the internal combustion engine is provided with a plurality of intake valves or exhaust valves, a variable mechanism may be provided for each of the intake valves and the exhaust valves. According to a second aspect of the present invention, the internal combustion engine is provided with a plurality of intake valves or exhaust valves for each cylinder, and the variable mechanism is independent of each intake valve or exhaust valve for each cylinder. It is also possible to adopt a mode in which driving is possible.

  According to this configuration, the opening / closing characteristics of a plurality of intake valves or exhaust valves provided in each cylinder are changed through a common variable mechanism. Absorption can be achieved through changing the opening / closing characteristics by the provided variable mechanism.

  According to a third aspect of the invention, in the invention of the first or second aspect, when the control means changes the opening / closing characteristics of the valve, a reaction force from the cam that opens the valve acts. The gist of the invention is to drive and control the variable mechanism during a non-period.

  When changing the opening and closing characteristics of the valve through the variable mechanism, the variable mechanism is driven during a period in which the valve driving force by the cam and the reaction force resulting therefrom, i.e., the force that impedes the driving of the variable mechanism, is applied. Energy loss is significant. In this regard, according to the configuration, the variable mechanism is driven during a period in which the valve driving force or reaction force is not acting, so that the energy required for driving the mechanism can be reduced as much as possible. become.

The gist of the invention according to claim 4 is that, in the invention according to any one of claims 1 to 3, each variable mechanism generates its driving force through an electric actuator.
For example, when each variable mechanism is hydraulically driven, it takes time until sufficient hydraulic pressure is secured for driving, and the response to the driving depends on the propagation speed of the hydraulic pressure. The response of the control is limited by them. In this respect, since the electric actuator is employed in the present invention, it is easy to ensure such controllability.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the variable mechanism changes the maximum lift amount of the valve as an opening / closing characteristic of the valve. The gist.

  According to the above configuration, the maximum lift amount can be changed only for some valves, and if there is an optimum period for changing the maximum lift amount only for some valves, for example, For all the valves, the maximum lift amount is not changed, and only the part of the valves can be changed.

  FIG. 1 shows a configuration around an engine valve in a gasoline engine (hereinafter abbreviated as “engine”) 10 as a multi-cylinder internal combustion engine. FIG. 1 shows a longitudinal section of one cylinder. FIG. 2 is a plan view for explaining the upper structure of the engine 10.

  The engine 10 is mounted on the vehicle for driving the vehicle. The engine 10 includes a cylinder block 11, a piston 12, a cylinder head 13 mounted on the cylinder block 11, and the like. The cylinder block 11 is formed with a plurality of cylinders, in this embodiment four cylinders 14, and each cylinder 14 is formed with a combustion chamber 15 defined by the cylinder block 11, the piston 12 and the cylinder head 13. Yes. Each cylinder 14 is provided with two intake valves 16 that are engine valves on the intake side and two exhaust valves 17 that are engine valves on the exhaust side. The intake valve 16 opens and closes the intake port 18, and the exhaust valve 17 opens and closes the exhaust port 19.

  The intake port 16 of each cylinder 14 is connected to a surge tank via an intake passage formed in the intake manifold, and supplies air from the surge tank to each cylinder 14 via an air cleaner. A fuel injector for injecting fuel into the intake port 18 of each cylinder 14 is disposed in each intake passage. In addition to the engine that injects fuel on the upstream side of the intake valve 16 as described above, an in-cylinder gasoline engine that injects fuel directly into each combustion chamber 15 can also be used.

  In the present embodiment, the intake air amount is adjusted by changing the maximum lift amount of the intake valve 16 by a variable mechanism 50 described later. Therefore, no throttle valve is disposed in the intake passage upstream of the surge tank. However, an auxiliary throttle valve may be arranged. When such an auxiliary throttle valve is arranged, for example, the auxiliary throttle valve is fully opened when the engine 10 is started, and the auxiliary throttle valve is fully closed when the engine 10 is stopped. For example, when the variable mechanism 50 fails, the intake air amount may be controlled by controlling the opening of the auxiliary throttle valve.

  The lift drive of the intake valve 16 can be performed by transmitting the valve drive force of the intake cam 22 provided on the intake camshaft 21 via the variable mechanism 50 and the roller rocker arm 20 arranged in the cylinder head 13. It has become. The intake valve 16 is closed by the spring force of the valve spring 28, and is lifted, that is, opened by the above-described valve driving force by the intake cam 22. One intake camshaft 21 drives all intake valves 16 to lift. The intake camshaft 21 rotates in conjunction with a crankshaft 24 of the engine 10 via a timing sprocket (may be a timing gear or a timing pulley) provided at one end thereof and a timing chain 23.

  The exhaust valve 17 of each cylinder 14 is opened and closed with a certain maximum lift amount via a roller rocker arm 27 by an exhaust cam 26 provided on an exhaust camshaft 25 that rotates in conjunction with the crankshaft 24. Each exhaust port 19 of each cylinder 14 is connected to an exhaust manifold, and exhaust is discharged to the outside through a catalytic converter.

Next, the variable mechanism 50 will be described.
The variable mechanism 50 changes the transmission state of the valve driving force transmitted from the intake cam 22 to the intake valve 16 via the roller rocker arm 20, thereby opening / closing characteristics of the intake valve 16, in this embodiment, the intake valve 16. The maximum lift amount can be adjusted.

  The variable mechanism 50 has a control shaft 51 to which a driving force for adjusting the maximum lift amount is input. The control shaft 51 is disposed in parallel with the intake camshaft 21 and is supported by the cylinder head 13 so as to be rotatable around the axis of the shaft 51. A rocker arm pressing member 52 is rotatably supported on the control shaft 51. The lower surface 52 a of the rocker arm pressing member 52 is in contact with the roller of the roller rocker arm 20.

  In addition, a swing arm support member 53 is fixed to the control shaft 51 with a bolt 54, so that the swing arm support member 53 can rotate integrally with the control shaft 51. A swing arm 55 is pivotally connected to the swing arm support member 53 with a pin 56 as a fulcrum. A roller 57 is provided at the free end of the swing arm 55, and the roller 57 comes into contact with the rocker arm pressing member 52. A roller 58 that is in contact with the cam surface of the intake cam 22 is provided at an intermediate portion of the swing arm 55.

  The intake cam 22, the roller 58 of the swing arm 55, the roller 57, the rocker arm pressing member 52, and the roller of the roller rocker arm 20 are affected by the action of the lash adjuster 59 provided on the fulcrum side of the roller rocker arm 20. Each contact described above is always maintained.

  In the variable mechanism 50 configured as described above, when the roller 58 of the swing arm 55 is pressed by the cam nose of the intake cam 22 (excluding the portion closest to the rotation center of the intake camshaft 21 on the cam surface). The roller 58 receives the valve driving force from the intake cam 22. When the roller 58 receives this valve driving force, the swing arm 55 is rotated about the pin 56 as a fulcrum. With this rotation, the rocker arm pressing member 52 is pressed by the roller 57 and the roller rocker arm 20 is pushed down by the lower surface 52a of the member 52, whereby the exhaust valve 17 is lifted. At this time, a reaction force caused by the spring force of the valve spring 28 that attempts to close the intake valve 16 (in other words, a reaction force caused by the valve driving force) acts on the variable mechanism 50. .

  In the variable mechanism 50, the maximum lift amount of the intake valve 16 can be changed by changing the position of the pin 56, that is, the fulcrum position of the swing arm 55 through the rotation of the control shaft 51. That is, when the roller 57 is moved in accordance with the change of the fulcrum position of the swing arm 55, the contact position between the roller 57 and the rocker arm pressing member 52 is shifted, and thereby the axis of the control shaft 51 is centered. The arrangement angle of the rocker arm pressing member 52 is changed. Due to the difference in the arrangement angle, the amount of movement of the roller rocker arm 20 accompanying the pressing when the roller 58 receives the valve driving force from the intake cam 22 changes, and the maximum lift amount changes. In the present embodiment, the working angle of the so-called intake cam 22 is also changed by changing the arrangement angle.

  Incidentally, the state of FIG. 1 is when the maximum lift amount of the intake valve 16 is minimized, and the maximum lift amount is increased by rotating the control shaft 51 clockwise from this state. In this embodiment, if the variable mechanism 50 is not receiving the valve driving force, the control shaft 51 is within the adjustment range of the maximum lift amount (range from the minimum maximum lift amount to the maximum maximum lift amount). The lower surface 52a of the rocker arm pressing member 52 is formed so that the intake valve 16 is not lifted as long as it is rotated at the position.

  In the present embodiment, the variable mechanism 50 configured as described above is provided for each cylinder 14, and the valve driving force from the intake camshaft 21 is independently generated without interlocking these mechanisms 50. It can be transmitted to the intake valve 16. One intake cam 22 is assigned to each cylinder 14 in the intake camshaft 21, and the intake cam 22 is connected to both intake valves 16 provided for each cylinder 14 via a variable mechanism 50. The valve driving force from 22 is transmitted.

  In the present embodiment, an electric motor 60 is individually provided for each mechanism 50 as an actuator for driving the control shaft 51 of the variable mechanism 50 to adjust the maximum lift amount. These electric motors 60 are independently driven based on drive signals output from an ECU (electronic control unit) 70.

  Thus, in the present embodiment, a plurality of variable mechanisms 50 provided for the same intake camshaft 21 can be independently driven by the electric motor 60. That is, the maximum lift amount can be changed only for a part of all the intake valves 16 that share the intake camshaft 21.

  Therefore, if there is an optimum period for changing the maximum lift amount only for some of the intake valves 16, for example, the maximum lift amount is not changed for all the other intake valves 16, for example. Only 16 will be able to change this. As a result, energy consumption in the electric motor 60 can be reduced, and energy can be concentrated on the variable mechanism 50 that needs to be driven, so that responsiveness when changing the maximum lift amount can be improved. . In the present embodiment, since the variable mechanism 50 is provided for each cylinder 14, the maximum lift amount of the intake valve 16 can be adjusted for each cylinder 14. For example, a plurality of cylinders 14 are provided in one variable mechanism. Compared with the case of assignment, the energy reduction and response improvement described above can be made more effective.

  Furthermore, in this embodiment, for example, when performing so-called cylinder stop in which the fuel supply is stopped in some cylinders 14, the maximum lift amount and the operating angle are changed so that the pumping loss is reduced only for the cylinders 14. Is also possible.

  Further, in an aspect in which these can not be independently driven, such as the variable mechanism in the above-described conventional aspect, for example, a machine is provided so that variations in each cylinder 14 with respect to the maximum lift amount of the intake valve 16 do not occur. It is necessary to make adjustments and is troublesome. In this respect, in the present embodiment, each variable mechanism 50 can be driven independently by the electric motor 60, so that the variation among the mechanisms 50 can be absorbed by setting the driving mode for each mechanism 50. become able to. Therefore, the adjustment work for the variable mechanism 50 can be reduced.

  Furthermore, since the variable mechanism 50 is provided for each cylinder 14, the variation can be absorbed for each cylinder 14 by setting the driving mode by the electric motor 60 for each cylinder 14. Thus, the adjustment work can be substantially omitted, that is, maintenance-free can be achieved.

  In the present embodiment, the variable mechanism 50 generates the driving force through the electric motor 60. For example, when each variable mechanism 50 is hydraulically driven, it takes time until a sufficient hydraulic pressure is ensured for driving, and the response with respect to the driving depends on the propagation speed of the hydraulic pressure. Eventually, the responsiveness of control is limited by them. In that respect, in the present embodiment, the use of the electric motor 60 makes it easy to ensure such controllability.

  Next, a connection structure between the electric motor 60 and the control shaft 51 in the variable mechanism 50 will be described. That is, the electric motor 60 and the control shaft 51 are drivingly connected via the worm mechanism 61. A worm 63 constituting the worm mechanism 61 is fixed to the output shaft 62 of the electric motor 60, and a worm wheel 64 constituting the worm mechanism 61 is also fixed to the end of the control shaft 51 serving as the input shaft. Since the output shaft torque of the electric motor 60 can be increased and converted and transmitted to the control shaft 51 by the worm mechanism 61, the output shaft torque of the electric motor 60 required to drive the shaft 51 can be made relatively small. The motor 60 can be downsized.

  As described above, the electric motor 60 is gear-coupled to obtain the driving force of the control shaft 51, so that the valve driving force of the intake cam 22 and the reaction force resulting therefrom are transmitted via the control shaft 51 to the electric motor. It is transmitted as load torque to 60 output shafts 62. In this case, when the output shaft 62 is driven and rotated by the load torque, there is a concern that the maximum lift amount cannot be maintained constant. In the present embodiment, paying attention to the fact that the driven rotation of the output shaft 62 due to such load torque can be made as difficult as possible by the worm mechanism 61, this is adopted and applied to the electric motor 60 for preventing the driven rotation. The power supply amount is reduced.

  By the way, in such an aspect having the intake cam 22 that generates a valve driving force to lift the intake valve 16, a load acting on the electric motor 60 when the maximum lift amount is changed increases when the maximum lift amount is increased. However, the amount of energy required for changing the maximum lift amount becomes larger than when it is decreased. In addition, when the valve lift is performed by the intake cam 22, the reaction force acts on the variable mechanism 50. Therefore, when the energy is changed during the valve lift, the maximum lift amount is changed. Is larger than when the valve lift is not performed.

  FIG. 3 is a time chart showing the change of the lift amount of the intake valve 16 and the load torque acting on the control shaft 51 of the variable mechanism 50 by the valve driving force and the reaction force with respect to a certain cylinder 14. It is a chart. In the figure, the state when the intake camshaft 21 is rotated at a substantially constant rotational speed is shown.

  As shown in the figure, when the intake valve 16 is lifted by the valve driving force of the intake cam 22, the load torque is much larger than when the intake valve 16 is not lifted. The peak P1 of the load torque at the time of valve lift during the change of the maximum lift amount by the variable mechanism 50 is larger than the other peaks.

  Further, in an aspect having a plurality of cylinders 14 as in the engine 10 of the present embodiment, the output torque fluctuations are generally changed by sequentially changing the cylinders 14 that are combusted while the crankshaft 24 rotates twice. I try to suppress it. Accordingly, the opening and closing of the intake valve 16 is sequentially performed in accordance with the change of the cylinder 14. In such a configuration, as the number of cylinders 14 increases, the opening and closing times of the intake valves 16 that are performed before the above-mentioned change is completed increase, so that the opening periods of the intake valves 16 are likely to approach or overlap between the cylinders 14.

  FIG. 4 shows the lift amount of each intake valve 16 in a configuration in which all the mechanisms 50 are driven by a common input shaft, for example, by directly connecting the control shafts 51 of each variable mechanism 50 of the present embodiment. It is the time chart which showed the aspect of the change about the load torque which acts on the said common input shaft. That is, in the above configuration shown in the figure, although the swing arm 55 and the rocker arm pressing member 52 in each variable mechanism 50 are provided for each cylinder 14, the swing arm support member 53 is rotated by a common input shaft, so that the maximum lift is achieved. This is a mode similar to the prior art in which the amount cannot be adjusted independently for each cylinder 14. Note that, also in this figure, as in FIG. 3, the state when the intake camshaft 21 is rotated at a substantially constant rotational speed is shown.

  In the variation of the lift amount shown in the figure, the solid line, the broken line, the alternate long and short dash line, and the alternate long and two short dashes line relate to different cylinders 14, respectively. As shown in the figure, as the maximum lift amount increases, the opening period (valve lift period) of the intake valves 16 between the cylinders 14 changes so that they overlap or the overlap amount increases. doing. It should be noted that the change mode of the load torque in the figure shows the sum of the load torques related to all the cylinders 14 acting on the common input shaft.

  Under such circumstances, the possibility that all the intake valves 16 are simultaneously closed (non-lifted) is reduced. For example, in the above-described conventional mode, the more the cylinders 14, the more the maximum lift amount is changed by the variable mechanism 50. There is a high possibility that any of the intake valves 16 is lifted. Therefore, in such a configuration, when the maximum lift amount is increased by the variable mechanism 50, there is a high possibility that the lift amount of the intake valve 16 that is already in the lifted state is further increased, and the load torque acting on the input shaft, that is, the same The load torque acting on the actuator for rotationally driving the input shaft tends to increase. As shown in FIG. 4, with respect to the load torque, a peak P11 of the load torque at the time of valve lift during the increase change of the maximum lift amount is larger than the other peaks.

  In the present embodiment, in order to reduce such load torque, the drive for increasing the maximum lift amount in the variable mechanism 50 is performed during a period when the intake valve 16 is not lifted (for example, periods t1 to t4 shown in FIG. 3). In other words, the valve driving force and the reaction force by the intake cam 22 are performed within a period during which the mechanism 50 is not applied. Hereinafter, the control aspect of ECU70 performed in order to implement | achieve the drive of such a variable mechanism 50 is demonstrated.

  The ECU 70 outputs a drive signal to the electric motor 60 based on input signals from the crank angle sensor 71, the air flow meter 72, the cam angle sensor 73, the motor rotation angle sensor 74, and the like. Thereby, the variable mechanism 50 for adjusting the maximum lift amount is driven.

  The flowchart of FIG. 5 shows a processing procedure of drive control of the variable mechanism 50 by the ECU 70 described above, and the ECU 70 repeatedly executes a series of processes shown in FIG.

  First, in step S100, it is determined whether or not a request for increasing the maximum lift amount of the intake valve 16 is made. Such a request is determined based on, for example, a request to increase the intake air amount. This determination process is repeated until the result of the determination is YES. If this determination is YES, which of the plurality of cylinders 14 is not lifted by the intake valve 16 in step S110. The determination process is performed.

  In this cylinder discrimination process, the rotational phase information of the intake camshaft 21 detected by the cam angle sensor 73 is referred to. When the cylinder 14 in which the intake valve 16 is not lifted is found, a drive signal is output to the corresponding electric motor 60 to drive the variable mechanism 50 of the cylinder 14 (step S120). In driving the variable mechanism 50, the drive amount, that is, the rotational displacement amount of the control shaft 51 is adjusted through feedback control based on the rotational phase information of the output shaft 62 of the electric motor 60 detected by the motor rotational angle sensor 74. The As a result, the maximum lift amount in the cylinder 14 where the intake valve 16 is not lifted is changed.

  The feedback control is not limited to the rotational phase information of the output shaft 62 as described above. For example, the rotational phase of the control shaft 51 may be detected and based on the detection result. Further, for example, the maximum lift amount information calculated from the engine rotational speed information detected by the crank angle sensor 71 and the intake air amount information detected by the air flow meter 72 or the like may be used.

  In step S120 described above, the remaining time until the next lift of the intake valve 16 for the cylinder 14 determined that the intake valve 16 is not lifted is the maximum lift by the variable mechanism 50. The drive start permission condition of the mechanism 50 is that the amount is sufficient to reach the target value. In other words, during the driving of the variable mechanism 50 for changing the maximum lift amount, the load torque of the electric motor 60 is not increased due to the valve driving force of the intake cam 22 acting on the mechanism 50. The variable mechanism 50 is limited.

  For the variable mechanism 50 that does not satisfy this condition and is not driven, and the variable mechanism 50 of the cylinder 14 that is determined to be lifted in the cylinder determination process, the intake valve 16 is closed. The driving is started after waiting. This standby time is calculated with reference to engine rotational speed information detected by the crank angle sensor 71, rotational phase information of the intake camshaft 21 detected by the cam angle sensor 73, and the like.

In the present embodiment, the following effects can be obtained.
(1) In the above-described embodiment, each variable mechanism 50 can be controlled separately. Therefore, the change timing of the maximum lift amount of the intake valve 16 can be set individually for each variable mechanism 50. Accordingly, when changing the maximum lift amount of each intake valve 16, for example, the change timing is set in a period in which the reaction force acting on each variable mechanism 50 is reduced based on the valve driving force by the intake cam 22, for example. As a result, the energy consumption in each variable mechanism 50 can be reduced, and as a result, the response when the maximum lift amount is changed can be improved.

  (2) According to the above-described embodiment, the maximum lift amount of the intake valves 16 provided in each cylinder 14 is changed through the common variable mechanism 50. Absorption can be achieved by changing the maximum lift amount by the variable mechanism 50 provided in units of 14 cylinders.

  (3) When the maximum lift amount of the intake valve 16 is changed through the variable mechanism 50, the valve driving force by the intake cam 22 and the reaction force resulting therefrom, that is, the period during which the force that hinders the driving of the variable mechanism 50 is acting. If the variable mechanism 50 is driven, energy loss becomes large. In this respect, according to the present embodiment, since the variable mechanism 50 is driven during a period in which the valve driving force or reaction force is not applied, the energy required for driving the mechanism 50 can be reduced as much as possible. Will be able to.

  (4) For example, when each variable mechanism 50 is hydraulically driven, it takes time until a sufficient hydraulic pressure is secured for driving, and the response with respect to the driving depends on the propagation speed of the hydraulic pressure. As a result, the responsiveness of control is ultimately limited by them. In this regard, in this embodiment, since the electric motor (electric actuator) 60 is employed, it is easy to ensure such controllability.

  (5) The electric motor 60 and the control shaft 51 are drivingly connected via the worm mechanism 61. According to this, since the output shaft torque of the electric motor 60 required for driving the control shaft 51 can be made relatively small, the electric motor 60 can be downsized. Further, the power supply amount for preventing the driven rotation of the output shaft 62 of the electric motor 60 based on the valve driving force of the intake cam 22 and the reaction force resulting therefrom can be reduced or eliminated. .

In addition, embodiment is not limited above, For example, it is good also as the following aspects.
In the above embodiment, the working angle of the intake valve 16 is changed with the change of the maximum lift amount. However, the present invention is not limited to this, and the maximum lift amount is changed without changing the working angle. You may make it apply this invention in an aspect.

  In the above embodiment, regarding the change in the increase in the maximum lift amount by the variable mechanism 50, the valve driving force from the intake cam 22 and the reaction force resulting therefrom are started within a period during which the variable mechanism 50 is not acting. Ended within the period. However, the present invention is not limited to this. For example, a part of the drive period of the variable mechanism 50 for increasing and changing the maximum lift amount overlaps with a period during which the valve driving force and reaction force are applied to the mechanism 50. May be. Even in this case, the degree of overlap during this period can be suppressed as much as possible through control of the drive timing of the electric motor 60, so that the energy can be reduced and the response can be improved. The effect of.

  In the above embodiment, the drive for increasing and changing the maximum lift amount in the variable mechanism 50 has been described. However, the valve driving force and reaction force are applied to the mechanism 50 with respect to the drive for changing and decreasing the maximum lift amount. You may make it carry out within the period which is not acting. Conversely, the drive for reducing and changing the maximum lift amount may be performed within a period during which the valve driving force or reaction force is applied to the mechanism 50. In this case, the amount of electric power supplied to the electric motor 60 can be reduced by using the valve driving force and reaction force as part of the energy required for the driving.

Instead of the electric motor 60, an actuator that hydraulically drives the variable mechanism 50 may be employed.
The control shaft 51 and the electric motor 60 are connected via the torque conversion means including the worm mechanism 61. However, the present invention is not limited thereto, and may be connected via a mechanism including a spur gear or the like.

  As long as a plurality of variable mechanisms 50 are provided for the same intake camshaft 21, for example, the variable mechanism 50 may be shared by a plurality of cylinders 14. Even in such a case, for example, as compared with a mode in which one variable mechanism 50 is used for the same intake camshaft 21, that is, the variable mechanism 50 is shared by all the cylinders 14, the energy reduction and responsiveness described above. Can be improved and the adjustment work can be reduced. Further, a variable mechanism 50 may be provided for each of a plurality of intake valves 16 provided.

A variable mechanism 50 may be provided for each intake valve 16, and this may be driven for each mechanism 50 by an actuator.
In the above embodiment, the variable mechanism 50 of the type that mediates the intake camshaft 21 and the intake valve 16 is used. However, the present invention is not limited to this, and the cam 22 directly contacts the roller rocker arm 20 and the intake valve 16. You may apply to an aspect. In this case, for example, each cam is provided on the camshaft so as to be independently slidable in the axial direction, and each cam has a profile that changes in the axial direction of the camshaft. According to this, by individually adjusting the slide movement amount of each cam, the maximum lift amount can be changed independently of the intake valve 16 corresponding to these cams.

  In the above embodiment, the opening / closing characteristic of the intake valve 16 changed by the variable mechanism is the maximum lift amount. However, the present invention is not limited to this, and the change amount of the lift amount from the minimum lift position to the maximum lift position may be used. Good. Further, the opening / closing characteristics relating to the lift amount are not limited to the opening / closing timing of the intake valve 16. In these cases, for example, each cam is provided independently relative to the cam shaft so as to be relatively rotatable around the axis. According to this, by individually adjusting the relative rotational phase of each cam with respect to the camshaft, the opening timing and the closing timing can be changed independently of the intake valves corresponding to these cams. In this case, by changing the relative rotational phase of the cam during the period when the valve driving force and the reaction force due to the cam are not acting, the energy consumption and response of the change are improved. Can be achieved.

  In the above embodiment, the present invention is applied to the variable mechanism that changes the opening / closing characteristics of the intake valve 16, but may be applied to the exhaust valve 17.

The longitudinal cross-sectional view of the engine in one Embodiment. The top view of the said engine. The time chart which showed the aspect of the change about the lift amount of an intake valve, and the load torque which acts on a control shaft. The time chart which showed the aspect of the change about the lift amount of an intake valve, and the load torque which acts on a control shaft regarding the conventional aspect. The flowchart regarding the drive control process of the variable mechanism which ECU performs.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Gasoline engine, 14 ... Cylinder, 16 ... Intake valve, 21 ... Intake cam shaft, 22 ... Intake cam, 50 ... Variable mechanism, 51 ... Control shaft, 60 ... Electric motor (electric actuator), 61 ... Worm mechanism, 63 ... Worm, 64 ... Worm wheel, 70 ... ECU (control means).

Claims (5)

In a valve opening / closing characteristic control device for an internal combustion engine that changes, through a variable mechanism, an opening / closing characteristic of a valve that is opened and closed by a plurality of cams formed on a camshaft of the internal combustion engine,
A valve opening / closing characteristic control apparatus for an internal combustion engine, comprising: a control unit configured to independently drive each of the variable mechanisms corresponding to the valves, and controlling each of the variable mechanisms. 2. The internal combustion engine according to claim 1, wherein the internal combustion engine is provided with a plurality of intake valves or exhaust valves for each cylinder, and the variable mechanism can independently drive these intake valves or exhaust valves for each cylinder. Valve opening / closing characteristics control device. 3. The internal combustion engine according to claim 1, wherein when changing the opening / closing characteristics of the valve, the control unit drives and controls the variable mechanism during a period in which a reaction force from the cam that opens the valve does not act. Valve opening / closing characteristics control device. The valve opening / closing characteristic control device for an internal combustion engine according to any one of claims 1 to 3, wherein each of the variable mechanisms generates a driving force through an electric actuator. The valve opening / closing characteristic control device for an internal combustion engine according to any one of claims 1 to 4, wherein the variable mechanism changes a maximum lift amount of the valve as an opening / closing characteristic of the valve.

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