JP2009091943A - Valve opening characteristic variable type internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To properly suppress the wild run of a member as part of a valve train, and to reduce a load on the valve train by stabilizing the deformed condition of an elastic means which is provided for suppressing the wild run, to reduce a stress fluctuation. <P>SOLUTION: The valve train changes the lift amount of a valve with the displacement of the rock supporting point of a roller link 22 which has a roller 31 located at the loose end and mounted between a cam 3 and a rocker arm 6. A coil spring 41 is provided for energizing the roller in the direction of pressing it against the cam. The coil spring is provided so that its energizing direction approximately corresponds to the moving direction of the roller during low lift control to reduce the lift amount of the valve. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a variable valve opening characteristic internal combustion engine in which valve opening characteristics such as a lift amount of a valve can be changed according to an operating state.

In recent years, internal combustion engines such as gasoline engines and diesel engines are increasingly equipped with various valve opening characteristic variable mechanisms in order to improve output and fuel consumption, reduce harmful exhaust gas components, and the like. As a valve opening characteristic variable mechanism, there is a mechanism that switches between a low speed type cam and a high speed type cam according to the operating condition, but in recent years it has been opened in order to further improve the transient characteristics and reduce the throttle. Some have continuously changed the valve characteristics (valve lift and valve timing) (see Patent Document 1).
Japanese Patent Laying-Open No. 2005-291101

  In this type of variable valve-opening-characteristic internal combustion engine, a configuration in which the valve-opening characteristic is changed by using a link mechanism is often used. It is desirable to have a configuration in which the members are held in pressure contact with each other, and in particular, the positional relationship between the cam and rocker arm and the link member changes according to the change in valve opening characteristics. Considering the above, it is desirable to arrange the spring at an appropriate position.

  In addition, when the spring of the member is suppressed by the urging force of the spring, the deformation state of the compression / extension of the spring changes according to the engine speed, and when this state change becomes unstable, the stress increases and the valve mechanism Therefore, it is desirable to avoid it.

  The present invention has been devised to solve such problems of the prior art, and the main purpose of the present invention is to appropriately suppress the rampage of the members constituting the valve operating mechanism, and further to the rampage. Provided is a variable valve opening characteristic internal combustion engine configured to be able to reduce a load applied to a valve operating mechanism by stabilizing a deformation state of an elastic means provided for suppression and reducing stress fluctuation. There is.

  In order to solve such a problem, according to the present invention, as shown in claim 1, the valve is opened and closed according to the operation of the valve (2) for intake or exhaust and the drive side member (cam 3). A rocker arm (6) to be moved, and a roller (31) interposed between the drive side member and the rocker arm on the free end side, and the lift amount of the valve is changed according to the displacement of the swing fulcrum. A roller link (22); and elastic means (coil spring 41) for urging the roller in a direction in which the roller is pressed against the driving side member. The elastic means includes the urging direction and the movement of the roller. It was assumed that the direction was substantially the same.

  According to this, since the urging direction of the elastic means and the moving direction of the roller substantially coincide with each other, the transmission efficiency of the elastic force of the elastic means, that is, the elastic force of the elastic means finally becomes the member on the driving side It is possible to increase the ratio of acting as the force for press contact, and to appropriately suppress the rampage of the member.

  And since the biasing direction of the elastic means and the movement direction of the roller substantially coincide, the deformation state of the elastic means can be stabilized and the stress fluctuation can be mitigated, thereby reducing the load on the valve mechanism. Can do. In addition, since the deformation direction of the elastic means and the movement direction of the roller substantially coincide with each other, no unnecessary force is generated, and it is difficult for the members to be displaced from each other, so that the friction between the members can be reduced.

  In the variable valve opening characteristic internal combustion engine, as shown in claim 2, the elastic means has an urging direction and a movement direction of the roller during low lift control with a small lift amount of the valve. It can be set as the structure provided so that it might correspond.

  According to this, at the time of low lift control, the transmission efficiency of the elastic force of the elastic means becomes high, and the deformation state of the elastic means can be stabilized.

  Although it is possible to provide two elastic means in the directions corresponding to each of the high lift control and the low lift control in which the valve lift amount is increased, only one elastic means is provided due to layout restrictions. If this is not possible, the elastic means may be arranged in a direction corresponding to the low lift control where the moving distance of the roller becomes large, and this can reduce the deformation of the elastic means and the friction between members.

  If the elastic means is arranged in the direction corresponding to the low lift control, the elastic force transmission efficiency of the elastic means decreases during the high lift control, but the valve is always urged in the closing direction during the high lift control. Since the urging direction of the valve spring and the moving direction of the roller substantially coincide with each other, a decrease in transmission efficiency of the elastic means can be compensated by the urging force of the valve spring.

  The biasing means is preferably a coil spring, but a torsion spring is also possible. In this case, it is preferable that the biasing force is increased during the low lift control, that is, the amount of bending of the torsion spring is increased at the position of the roller during the low lift control.

  As described above, according to the present invention, the urging direction of the elastic means and the movement direction of the roller substantially coincide with each other, so that the transmission efficiency of the elastic force of the elastic means is improved, and the violence of the member is appropriately suppressed. In addition, the deformation state of the elastic means can be stabilized and stress fluctuations can be mitigated, thereby reducing the load on the valve operating mechanism, and further reducing friction between members, and durability. A great effect is obtained in increasing the reliability.

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

  FIG. 1 is a perspective view showing an upper portion of an engine according to the present invention. FIG. 2 is a perspective view showing a valve opening characteristic variable mechanism of the engine shown in FIG. FIG. 3 is a schematic diagram showing an operation state of the valve opening characteristic variable mechanism shown in FIG.

  This engine (variable valve opening characteristic type internal combustion engine) is an in-line four-cylinder engine mounted on an automobile. The cylinder head 1 includes two exhaust valves 2 for each cylinder. As a valve operating mechanism for driving the cam 2, a camshaft 4 having a cam 3, a rocker arm 6 interposed between the valve 2 and the cam 3, and a valve spring 7 for constantly urging the valve 2 in the closing direction are provided. Is provided.

  On the intake side, two intake valves 8 are provided for each cylinder, and a camshaft, a rocker arm, and a valve spring (not shown) are provided as valve operating mechanisms for driving the valves. ing.

  The cam shaft 4 is rotatably supported by the cam holder 11. The cam holder 11 is provided so as to partition a valve operating chamber for each cylinder, and is fastened and fixed to the upper surface of the cylinder head 1 with a bolt.

  This engine is equipped with a variable valve opening characteristic mechanism that variably controls the lift amount of the valve 2. This variable valve opening characteristic mechanism has a link mechanism that is driven by an electric motor (actuator) 14 installed on the upper surface of the base plate 13.

  As shown in FIG. 2, the link mechanism includes a control shaft 20 that extends in the lateral direction, a gear link 21 that is rotatably supported by the cam holder 11 and holds the control shaft 20 so as to be rotatable, and a control shaft. 20 and a roller link 22 interposed between the cam 3 and the rocker arm 6 on the free end side.

  The roller link 22 is provided for each cylinder, and operates in conjunction with the turning of the control shaft 20 accompanying the rotation of the gear link 21, and the valve 2 according to the displacement of the swing fulcrum of the roller link 22 caused thereby. The lift amount is changed. The control shaft 20 is rotatably supported by the cam holder 11 via the link holder 30. The rotation center lines of the gear link 21 and the roller link 22 are parallel to each other.

  The gear link 21 includes an arm portion 24 that rotates around a support shaft 23 provided in the cam holder 11, and a gear portion 25 that extends from the free end side of the arm portion 24 in the circumferential direction and meshes with the drive gear 17. And is rotated by the driving force of the electric motor 14. A shaft holder 26 that holds the control shaft 20 in a rotatable manner is formed on the free end side of the arm portion 24.

  The roller link 22 has a base portion 28 that is fitted to the control shaft 20 and serves as a rocking fulcrum, and a pair of arm portions 29 extending from the base portion 28. At the tip of the arm portion 29, there are a roller 31 that is in rolling contact with the cam 3 of the camshaft 4 and a roller shaft 32 that is in contact with the slipper surface of the rocker arm 6.

  The rocker arm 6 includes a base portion 35 rotatably supported by a rocker shaft 34 held by the cam holder 11, and a pair of arm portions 36 extending from the base portion 35, and the pair of arms As shown in FIG. 3, each part 36 is provided with an adjusting screw 39 for adjusting the position of a tip part 38 that presses the stem end 37 of the valve 2.

  In the valve opening characteristic variable mechanism configured as described above, the gear link 21 rotates about the support shaft 23 (see FIG. 2) as the drive gear 17 rotates, and the roller is accordingly generated. The control shaft 20 serving as the swing fulcrum of the link 22 is displaced, and the lift amount of the valve 2 can be adjusted steplessly according to the rotational angle position (link angle) of the gear link 21.

  When reducing the valve lift during idling or the like, the gear link 21 is set to the minimum lift position (for example, link angle = 0 degree) shown in FIG. 3A, and in this case, it becomes the swing fulcrum of the roller link 22. Even if the control shaft 20 is positioned above the rocker arm 6 and the roller 31 is pushed down by the cam 3, the roller shaft 32 rolls along the slipper surface 33 as indicated by the arrow, so that the rocker arm 6 swings. (That is, the lift amount of the valve 2) is reduced.

  On the other hand, when increasing the valve lift during high load operation or the like, the gear link 21 is set to the maximum lift position (for example, link angle = 60 degrees) shown in FIG. 3B, and in this case, the roller link 22 is swung. When the control shaft 20 serving as a fulcrum is located on the side of the rocker arm 6 and the roller 31 is pushed down by the cam 3, the roller shaft 32 hardly rolls along the slipper surface 33. The amount increases.

  4 is a perspective view showing a main part of the variable valve opening characteristic mechanism shown in FIG. FIG. 5 is a longitudinal sectional view showing an operation state of the coil spring shown in FIG. FIG. 6 is a longitudinal sectional view showing another example of the coil spring. FIG. 7 is a longitudinal sectional view showing another example of the variable valve opening characteristic mechanism.

  As shown in FIG. 4, the variable valve opening characteristic mechanism is provided with a coil spring (elastic means) 41 that biases the roller 31 of the roller link 22 in a direction in which the roller 31 is pressed against the cam (drive-side member) 3. . One end of the coil spring 41 is attached with a roller contact member 42 that contacts the outer peripheral surface of the roller 31 on the side opposite to the cam 3, and the other end is held by a spring holding portion 44 of the bracket 43. The bracket 43 is fastened and fixed to the upper surface of the cylinder head 1 with bolts.

As shown in FIG. 5, the coil spring 41 has its urging direction, that is, the direction of the pressing force acting on the roller 31 from the roller contact member 42 (direction of the spring reaction force F _SPG ), and FIG. The movement direction of the roller 31 at the time of low lift control with a small lift amount of the valve 2 shown in FIG. 2, that is, the tangential direction with respect to the turning circle of the roller 31 around the swing fulcrum of the roller link 22 is provided. ing.

At the time of the low lift control shown in FIG. 5A (for example, the link angle = 0 degree), the roller 31 rotates in the direction indicated by the arrow around the control shaft 20 according to the rotation of the cam 3, and accompanying this The coil spring 41 expands and contracts. At this time, the biasing direction of the coil spring 41 (the direction of the spring reaction force F _SPG ) and the movement direction of the roller 31 substantially coincide. For this reason, the deformation state of the compression / extension of the coil spring 41 is stabilized. In addition, the transmission efficiency of the elastic force of the coil spring 41, that is, the ratio at which the elastic force of the coil spring 41 finally acts as a force that presses the roller 31 against the cam 3 increases.

On the other hand, at the time of the high lift control shown in FIG. 5B (for example, link angle = 60 degrees), the roller 31 rotates in the direction indicated by the arrow according to the rotation of the cam 3, and the coil spring 41 is moved accordingly. Although it expands and contracts, at this time, the biasing direction of the coil spring 41 (the direction of the spring reaction force F _SPG ) and the moving direction of the roller 31 are greatly different. For this reason, the deformation state of the compression / extension of the coil spring 41 becomes unstable. Further, the transmission efficiency of the elastic force of the coil spring 41 is lowered.

In the example shown in FIG. 6, the arrangement direction of the coil spring 61 is changed. The coil spring 61 includes the biasing direction (the direction of the spring reaction force F _SPG ) and the high lift control shown in FIG. It is provided so that the direction of movement of the roller 31 at the time substantially coincides. In this example, at the time of the high lift control shown in FIG. 6B, the transmission efficiency of the elastic force of the coil spring 61 is increased, and the deformation state of the compression / extension of the coil spring 61 is stabilized.

The example shown in FIG. 7 is obtained by changing the layout of each member such as the shape of the roller link 22 and the relative position of the swing fulcrum as compared with the above example. In this example, the shape of each member is different from that in the above example, but those having the same function will be described with the same reference numerals. In this example, as in the example of FIG. 5, the coil spring 71 has its urging direction (the direction of the spring reaction force F _SPG ) and the direction of movement of the roller 31 during the low lift control shown in FIG. Are substantially matched.

  As clearly shown in the example of FIG. 7, during the low lift control, the amount of displacement of the rocker arm 6 on the slipper surface 33 is increased by reducing the lift amount of the valve 2, that is, the rocking amount of the rocker arm 6. Accordingly, the moving distance of the roller 31 increases. On the other hand, at the time of high lift control, by increasing the lift amount of the valve 2, the displacement amount of the rocker arm 6 on the slipper surface 33 is reduced, and the moving distance of the roller 31 is also reduced.

  For this reason, when the coil spring is arranged in a direction corresponding to the high lift control shown in FIG. 7B, the roller 31 moves greatly in a direction different from the expansion / contraction direction of the coil spring in the low lift control shown in FIG. As a result, the coil spring falls and deforms, and the friction between members becomes significant. Therefore, it is preferable to arrange the coil spring in the direction corresponding to the low lift control as in the examples of FIGS.

  Further, when the coil spring is arranged in the direction corresponding to the low lift control as in the examples of FIGS. 5 and 7, the transmission efficiency of the spring force of the coil spring is reduced during the high lift control. Sometimes, the urging direction of the valve spring 7 and the moving direction of the roller 31 substantially coincide with each other, so that the urging force of the valve spring 7 can compensate for a decrease in transmission efficiency of the coil spring.

  FIG. 8 is a graph showing the state of the stress amplitude generated in the coil spring. In the embodiment shown in FIG. 8A, as shown in FIG. 5, the coil spring 41 is arranged so that the urging direction thereof substantially coincides with the direction of movement of the roller 31 during the low lift control. Is the case. The comparative example shown in FIG. 8B is a case where the coil spring is arranged in the same direction as the valve spring 7.

  In the comparative example shown in FIG. 8B, a large variation in the stress amplitude occurs, whereas in the example shown in FIG. 8A, the variation in the stress amplitude is small, and the coil spring It can be seen that the deformation state is stabilized and the stress fluctuation is suppressed to a small level.

  In the above example, the coil spring is used as the elastic means. However, the present invention is not limited to this, and various elastic means such as a torsion spring or a rubber material can be used. .

It is a perspective view which shows the upper part of the engine by this invention. It is a perspective view which shows the valve opening characteristic variable mechanism of the engine shown in FIG. It is a schematic diagram which shows the operation | movement condition of the valve opening characteristic variable mechanism shown in FIG. FIG. 3 is a perspective view showing a main part of the valve opening characteristic variable mechanism shown in FIG. 2. It is a longitudinal cross-sectional view which shows the operation | movement condition of the coil spring shown in FIG. It is a longitudinal cross-sectional view which shows another example of a coil spring. It is a longitudinal cross-sectional view which shows another example of a valve opening characteristic variable mechanism. It is a graph which shows the condition of the stress amplitude which generate | occur | produces in a coil spring.

Explanation of symbols

2 Valve 3 Cam (Drive-side member)
4 camshaft 6 rocker arm 7 valve spring 20 control shaft 21 gear link 22 roller link 31 roller 32 roller shaft 33 slipper surface 41 coil spring (elastic means)
42 Roller contact member 43 Bracket 44 Spring holding portion 61 Coil spring

Claims (2)

A valve for intake or exhaust, and
A rocker arm that opens and closes the valve according to the operation of the drive side member;
A roller link provided on the free end side with a roller interposed between the drive-side member and the rocker arm, and changing the lift amount of the valve in accordance with the displacement of the swing fulcrum;
Elastic means for urging the roller in a direction in which the roller is pressed against the driving side member;
A variable valve opening characteristic internal combustion engine, characterized in that the elastic means is provided so that the urging direction thereof substantially coincides with the moving direction of the roller.   The said elastic means is provided so that the urging | biasing direction and the moving direction of the said roller at the time of the low lift control which made the lift amount of the said valve | bulb small could substantially correspond. An internal combustion engine with variable valve opening characteristics.

Images