JP2010261349A - Variable valve gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable valve gear capable of restraining abrasion of a slider surface by a slide of an intermediate member, in the variable valve gear. <P>SOLUTION: A slider member 36L is arranged outside an intermediate arm 28L. The slider member 36L moves along the slider surface 22L and a peripheral surface of a cam 16 while keeping a distance from a pin 30 constant. A shape of an abutting surface where the slider member 36L abuts on the slider surface 22L, is formed in a slipper shape of expanding in the slide direction. A contact surface radius of this abutting surface is formed equal to a surface constituting radius of the slider surface 22L. Bearing pressure impressed on the slider surface 22L from this abutting surface can be reduced thereby. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a variable valve operating apparatus, and more particularly to a variable valve operating apparatus including an intermediate member that transmits an acting force of a drive cam to a slider surface of a swing arm.

  Conventionally, for example, in Patent Document 1, a swing arm that swings around an axis parallel to the cam shaft and drives the valve in the lift direction by the acting force of the drive cam is opposed to the cam surface of the drive cam. The slider surface formed on the swing arm, and disposed between the drive cam and the swing arm, abuts both the cam surface and the slider surface, and slides on the slider surface to There is disclosed a variable valve operating apparatus that includes an intermediate member that transmits an acting force of a drive cam to the slider surface.

  The intermediate member provided in the conventional apparatus is a member including a cam roller that contacts the cam surface, and a slider roller that can rotate with respect to the cam roller and that contacts the slider surface. Therefore, when the drive cam rotates, the acting force can be transmitted from the cam surface to the slider surface via the cam roller and slider roller of the intermediate member. Therefore, the conventional device includes this intermediate member, so that the operating force of the drive cam can be transmitted to the swing arm, and the valve can be driven in the lift direction.

International Publication No. 2006/025565 JP 2008-309040 A JP 2001-329816 A

  In the variable valve operating apparatus represented by the above-described conventional apparatus, lubricating oil is usually supplied onto the slider surface for the purpose of suppressing an increase in friction generated between the slider roller of the intermediate member and the slider surface. However, when such a variable valve operating apparatus is applied to a diesel engine, black smoke particles generated during combustion may dissolve in the lubricating oil. When the black smoke particles are dissolved in the lubricating oil, the slider surface may be worn by sliding of the slider roller. When wear of the slider surface progresses, the adjusted mounting angle is affected, and the valve operating angle and the lift amount may be affected.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a variable valve operating device that can suppress wear of a slider surface due to sliding of an intermediate member.

In order to achieve the above object, a first invention is a variable valve gear,
A drive cam provided on the camshaft;
A swing arm that swings about an axis parallel to the cam shaft and that drives the valve in the lift direction by the acting force of the drive cam;
A slider surface with a constant curvature formed on the swing arm so as to face the cam surface of the drive cam;
It is disposed between the drive cam and the swing arm, abuts on both the cam surface and the slider surface, and transmits the acting force of the drive cam to the slider surface by sliding on the slider surface. An intermediate member,
The curvature of the contact surface of the intermediate member that contacts the slider surface is equal to the curvature of the slider surface.

The second invention is the first invention, wherein
A guide groove formed in a sliding range of the intermediate member on the slider surface;
A protrusion formed on the contact surface and slidable while engaging the side wall of the guide groove;
The groove width of the guide groove is formed so as to increase as the distance from the position near the center of the curvature circle of the slider surface increases.

  According to the first invention, since the curvature of the contact surface of the intermediate member that contacts the slider surface is configured to be equal to the curvature of the slider surface, the surface pressure applied from the contact surface to the slider surface is reduced. it can. Thereby, the abrasion of the slider surface by the slide of an intermediate member can be suppressed. Accordingly, it is possible to reduce the change in the working angle and the maximum valve lift amount due to wear, and it is possible to suppress deterioration in engine performance and exhaust emissions due to insufficient valve overlap and intake air amount.

  According to the second aspect of the invention, the protrusion is formed so as to be slidable while engaging with the side wall of the guide groove, so that the intermediate member can be prevented from being detached from the slider surface. Therefore, it is possible to prevent noise due to re-contact between the intermediate member and the slider surface that occurs when the intermediate member is detached, and to prevent damage to the entire apparatus including the intermediate member and the slider surface due to an impact at the time of re-contact. In addition, it is possible to suppress the occurrence of abnormal movement such as valve jumping and bounce during high rotation.

1 is a perspective view showing a variable valve operating apparatus according to Embodiment 1. FIG. 3 is an exploded perspective view of a characteristic part of the first embodiment. FIG. It is sectional drawing in the plane perpendicular | vertical to a control axis in the characteristic part of the variable valve apparatus of Embodiment 1. FIG. It is a top view of a control shaft and a control shaft drive device. It is a side view of a control axis drive device. It is a perspective view which shows the conventional variable valve apparatus as a comparison object. It is sectional drawing in the plane perpendicular | vertical to a control axis | shaft in the relevant part of the conventional variable valve apparatus as a comparison object of the characteristic part of Embodiment 1. FIG. It is a figure which shows transition of the working angle and lift amount of a valve | bulb. FIG. 6 is a perspective view showing a variable valve apparatus according to a modification of the first embodiment. FIG. 10 is an exploded perspective view of a characteristic part of a modification of the first embodiment. FIG. 6 is a cross-sectional view taken along a plane perpendicular to a control axis, in a characteristic part of a variable valve apparatus according to a modification of the first embodiment. 6 is a perspective view showing a variable valve operating apparatus according to Embodiment 2. FIG. 5 is an enlarged perspective view of a swing arm used in Embodiment 2. FIG. 6 is an enlarged perspective view of a slider member used in Embodiment 2. FIG.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted or simplified.

Embodiment 1 FIG.
First, the structure and the characteristic part of the variable valve operating apparatus of this Embodiment 1 are demonstrated using FIGS. 1-3. 1 is described as driving the intake valves 12R and 12L of the diesel engine, the variable valve operating apparatus 10 shown in FIG. 1 can also be applied to a variable valve driving apparatus that drives an exhaust valve.

  The variable valve operating apparatus 10 includes a cam 16 provided on a camshaft 14 that is rotationally driven by a crankshaft of a diesel engine. The variable valve operating apparatus 10 includes a control shaft 18 arranged in parallel with the cam shaft 14 and a control shaft driving device capable of rotating the control shaft 18 within a predetermined angle range. This control shaft driving device will be described later.

  The variable valve operating apparatus 10 includes swing arms 20L and 20R. The swing arms 20L and 20R are installed so as to be swingable about the control shaft 18. Slider surfaces 22L and 22R are formed on the swing arms 20L and 20R on the side facing the cam surface of the cam 16, respectively. Further, swing cam surfaces 24L and 24R are formed on the opposite sides of the slider surfaces 22L and 22R of the swing arms 20L and 20R, respectively.

  A control arm 26 is disposed between the swing arms 20L and 20R. The control arm 26 is integrally fixed to the control shaft 18. The control arm 26 protrudes in the radial direction of the control shaft 18, and intermediate arms 28 </ b> L and 28 </ b> R are attached to the protruding portion. The intermediate arms 28L and 28R are provided on both sides of the control arm 26 so as to sandwich the control arm 26 therebetween.

  As shown in FIGS. 2 and 3, the intermediate arms 28 </ b> L and 28 </ b> R are formed to be curved along the control shaft 18. The rear ends of the intermediate arms 28L and 28R are rotatably connected to the control arm 26 by pins 30. The position of the pin 30 is eccentric from the center of the control shaft 18, and the position of the pin 30 is the center of swinging of the intermediate arms 28L and 28R. On the other hand, the front ends of the intermediate arms 28L and 28R are connected to each other by a connecting shaft 32. A cam roller 34 is disposed between the intermediate arms 28L and 28R of the connecting shaft 32, and the cam roller 34 is rotatably supported by the connecting shaft 32.

  In addition, slider members 36L and 36R are disposed outside the intermediate arms 28L and 28R, respectively. The slider members 36L and 36R move along the slider surfaces 22L and 22R and the circumferential surface of the cam 16 while keeping the distance from the pin 30 constant. In addition, the shape of the contact surface (hereinafter, “contact surface of the slider members 36L, 36R”, etc., simplified) such that the slider members 36L, 36R contact the slider surfaces 22L, 22R is a slipper-like shape that expands in the slide direction. Is formed. In addition, it is preferable to lighten the thickness portions of the slider members 36L and 36R by stealing meat.

  Here, as shown in FIG. 3, the contact surface radius of the contact surface of the slider member 36L is formed to be equal to the surface configuration radius of the slider surface 22L. Such a diameter can be determined as follows. First, on the basis of the case where the slider member 36L is located closest to the control shaft 18, the radius R of the arc forming the slider surface 22L from the control shaft 18 side toward the tip side is determined by the position of the slider surface 22L. Keep it constant. Next, an arc shape equal to the arc radius R is formed on the contact surface of the slider member 36L. Thus, by forming the surface configuration radius of the slider surface 22L and the contact surface radius of the contact surface of the slider member 36L equal, the surface pressure applied from the contact surface to the slider surface 22L can be reduced. The contact surface radius of the contact surface of the slider member 36R can be determined by the same method. These contact surface radii are preferably finely adjusted in accordance with actual contact conditions.

  The swing arms 20L and 20R are biased by lost motion springs 38L and 38R (counterclockwise in FIG. 3). With this urging force, the swing arms 20L and 20R are pressed against the slider members 36L and 36R, and the cam roller 34 is pressed against the cam 16.

  The variable valve operating apparatus 10 further includes rocker arms 40L and 40R that press the valve shafts of the intake valves 12L and 12R in the lift direction. The rocker arms 40L and 40R are disposed below the swing arms 20L and 20R. Rocker arm rollers 42L and 42R are rotatably attached to intermediate portions of the rocker arms 40L and 40R, respectively. The rocker arm rollers 42L and 42R are in contact with the swing cam surfaces 24L and 24R. One ends of the rocker arms 40L, 40R are in contact with the valve shaft ends of the intake valves 12L, 12R, and the other ends of the rocker arms 40L, 40R are supported by lash adjusters 44L, 44R. The intake valves 12L and 12R are biased by valve springs 46L and 46R in the closing direction, that is, in the direction of pushing up the rocker arms 40L and 40R. The rocker arm rollers 42L and 42R are pressed against the swing cam surfaces 24L and 24R by this urging force and the lash adjusters 44L and 44R.

  In such a variable valve operating apparatus 10, when the cam 16 rotates, the cam lift of the cam 16 is transmitted to the slider surfaces 22L and 22R via the cam roller 34 and the slider members 36L and 36R, thereby swinging arms 20L and 20R. Swings.

  When the swing arm 20L, 20R swings, when the slider member 36L is at the position closest to the center of the control shaft 18, the cam lift of the cam 16 is transmitted to the swing arm 20L at a position close to the center of the control shaft 18. It will be. For this reason, the swing range (swing width) of the swing arm 20L is increased. As a result, the operating angle and the maximum lift amount of the intake valve 12L increase. Conversely, when the slider member 36L is at a position far from the center of the control shaft 18, the cam lift of the cam 16 is transmitted to the swing arm 20L at a position far from the center of the control shaft 18. For this reason, the swing range (swing width) of the swing arm 20L is reduced. As a result, the operating angle and the maximum lift amount of the intake valve 12L are reduced.

  A control shaft drive device that enables such a working angle and maximum lift amount will be described with reference to FIGS. 4 and 5. FIG. 4 is a plan view of the control shaft 18 and the control shaft drive device, and FIG. 5 is a side view of the control shaft drive device. As shown in FIG. 4, the control shaft 18 is shared by the variable valve gear 10 of each cylinder of # 1 to # 4. As shown in FIGS. 4 and 5, a reduction gear 48 is fixed to one end of the control shaft 18. The reduction gear 48 is engaged with the reduction gear 50. A worm wheel 52 is provided on the same axis as the reduction gear 50. The worm wheel 52 meshes with the worm gear 54. The worm gear 54 is fixed to the output shaft of the motor 56. By operating the motor 56, the control shaft 18 can be rotated via the gear train.

  By the way, in the conventional variable valve operating apparatus 70 as shown in FIGS. 6 and 7, the slider rollers 72L and 72R move along the periphery of the slider surfaces 22L and 22R. At this time, lubricating oil is supplied onto the slider surfaces 22L and 22R to reduce friction with the slider rollers 72L and 72R. When such a variable valve apparatus 70 is applied to a diesel engine, there are the following problems. That is, in the diesel engine, fuel is diffusely supplied into the cylinder, so that uniform combustion is difficult, and as a result, black smoke and particulate matter (PM) are likely to be generated. For this reason, when the generated substance is dissolved in the lubricating oil, the lubricating oil and the generated substance function like a slurry, and the slider surfaces 22L and 22R may be worn by sliding of the slider rollers 72L and 72R.

  FIG. 8 is a graph showing changes in the valve operating angle and the lift amount. A characteristic curve A in FIG. 8 shows the operating angle and the lift amount when the variable valve apparatus 70 is assembled (at the initial stage). On the other hand, when the combustion generating material is dissolved in the lubricating oil, wear on the slider surfaces 22L and 22R side having a large surface configuration radius mainly proceeds. As a result, as shown in the characteristic curve B of FIG.

  Therefore, in the first embodiment, instead of the slider rollers 72L and 72R, the slider members 36L and 36R having a contact surface radius equal to the surface configuration radius of the slider surfaces 22L and 22R are used. By doing so, while maintaining the function of the slider rollers 72L and 72R that keeps the distance between the center of the coupling shaft 32 and the slider surfaces 22L and 22R constant, the slider surface from the contact surface of the slider members 36L and 36R. The surface pressure applied to 22L and 22R can be reduced. Therefore, it is possible to reduce the operating angle and the amount of change in the lift amount due to the progress of wear of the slider surfaces 22L and 22R. As a result, it is possible to suppress the delay in valve opening timing and the progress of the closing timing, insufficient valve overlap due to a decrease in time area, engine performance degradation and exhaust emission deterioration due to insufficient intake air amount.

  Moreover, generation | occurrence | production of the process cost for diesel engines, such as surface treatment, can be suppressed to slider roller 72L, 72R by using slider member 36L, 36R. Furthermore, the contact area with the slider surfaces 22L and 22R can be increased compared to the slider rollers 72L and 72R. As a result, the posture positions of the swing arms 20L, 20R and the connecting shaft 32 can be stabilized, and the lift difference between the intake valves 12L, 12R can be reduced. Also, skew of the cam needle roller can be prevented and uneven wear can be suppressed. Further, noise due to re-contact with the slider surfaces 22L and 22R can be reduced by valve jump or the like.

  In the first embodiment, the slider members 36L and 36R in which the contact surfaces of the slider members 36L and 36R are formed in a slipper shape are used. However, the slipper shape is also formed on the cam surface side of the cam 16. It may be formed. Specifically, description will be made with reference to FIGS. As shown in FIGS. 9 and 10, the slider members 58L and 58R move along the periphery of the slider surfaces 22L and 22R. Further, as shown in FIG. 11, the contact surface radius of the contact surface of the slider member 58L is formed to be equal to the surface configuration radius of the slider surface 22L. Further, a surface equal to the surface configuration radius of the slider surface 22L is formed on the opposite side of the contact surface of the slider member 58L.

  In this way, by forming the slipper-like shape on both sides, the center of gravity of the slider members 58L and 58R is stabilized, so that swinging at high rotation can be stabilized. Further, even when the slider members 58L and 58R are inverted during the assembly of the members, the assembly can be performed without any problem. Furthermore, when reassembly is performed for repair or the like, the unused surface can be set as the contact surface of the slider members 58L and 58R. Note that this modification can also be applied to Embodiment 2 described later.

  In the first embodiment described above, the members including the connecting shaft 32, the cam roller 34, and the slider members 36L and 36R correspond to the “intermediate member” in the first invention.

Embodiment 2. FIG.
Next, the configuration and characteristic parts of the variable valve operating apparatus according to the second embodiment will be described with reference to FIGS.

  The variable valve apparatus 60 of the second embodiment includes swing arms 20L and 20R. Slider surfaces 22L and 22R are formed on the swing arms 20L and 20R on the side facing the cam surface of the cam 16, respectively. Further, slider members 36L and 36R are disposed in contact with the slider surfaces 22L and 22R. The contact surface radius of the contact surface of the slider members 36L and 36R is formed to be equal to the surface configuration radius of the slider surfaces 22L and 22R.

  Slide grooves 62L and 62R are formed in the center portions of the slider surfaces 22L and 22R, respectively, along the slide direction. FIG. 13 shows an enlarged perspective view of the swing arm 20L. The slide groove 62L is formed as a trapezoidal groove in which the groove width of the opening is narrower than the groove width of the innermost part. An oil supply hole 64 </ b> L is formed in the bottom part constituted by the set of trapezoidal bottoms. The oil supply hole 64 </ b> L is provided for supplying lubricating oil from the control shaft 18. Thereby, the increase in the friction at the time of the projection part 66L mentioned later sliding the slide groove | channel 62L can be suppressed. The oil supply hole 64L is preferably formed in the vicinity of the position where the maximum surface pressure is applied during the valve lift period. This is preferable because the occurrence of oil film breakage during the valve lift period can be suppressed.

  On the other hand, as shown in FIG. 14, a trapezoidal protrusion 66 </ b> L substantially the same as the shape of the slide groove 62 </ b> L is formed on the contact surface of the slider member 36 </ b> L. By forming in this way, the protrusion 66L can have a retaining function, and when the slider member 36L slides on the slider surface 22L, it can slide while engaging with the side wall of the slide groove 62L.

  Thus, by forming the slider members 36L and 36R and the slide grooves 62L and 62R, it is possible to reliably prevent the slider members 36L and 36R from being detached from the swing arms 20L and 20R. Therefore, it is possible to prevent noise caused by re-contact between the slider members 36L and 36R and the slider surfaces 22L and 22R that are generated during the detachment. Further, it is possible to prevent damage to the entire apparatus including the intermediate member and the slider surface due to the impact at the time of re-contact. In addition, it is possible to suppress the occurrence of abnormal movement such as valve jumping and bounce during high rotation.

  In the second embodiment, the groove widths of the slide grooves 62L and 62R are formed narrower than the innermost part thereof, but in addition to this, the tip of the slider surfaces 22L and 22R, that is, Alternatively, it may be formed wider as the distance from the position near the swing center of the swing arms 20L, 20R increases. The swing arms 20L and 20R are pushed down in conjunction with the rotation of the crankshaft. For this reason, friction is likely to be generated between the slide grooves 62L and 62R and the protrusions 66L and 66R, particularly when pushed down. Therefore, by gradually changing the shape of the slide grooves 62L and 62R as in this modification, the friction at the time of pressing down can be reduced. In this case, the groove width of the opening at the position farthest from the swing center of the swing arms 20L and 20R needs to be wider than the protrusion width at the tip of the protrusions 66L and 66R.

10, 60 Variable valve gear 12L, 12R Intake valve 14 Cam shaft 16 Cam 18 Control shaft 20L, 20R Swing arm 22L, 22R Slider surface 26 Control arm 28L, 28R Intermediate arm 30 Pin 32 Connection shaft 34 Cam roller 36L, 36R , 58L, 58R Slider member 62L, 62R Slide groove 66L, 66R Protrusion

Claims (2)

A drive cam provided on the camshaft;
A swing arm that swings about an axis parallel to the cam shaft and that drives the valve in the lift direction by the acting force of the drive cam;
A slider surface with a constant curvature formed on the swing arm so as to face the cam surface of the drive cam;
It is disposed between the drive cam and the swing arm, abuts on both the cam surface and the slider surface, and transmits the acting force of the drive cam to the slider surface by sliding on the slider surface. An intermediate member,
The variable valve operating apparatus, wherein a curvature of a contact surface of the intermediate member that contacts the slider surface is equal to a curvature of the slider surface. A guide groove formed in a sliding range of the intermediate member on the slider surface;
A protrusion formed on the contact surface and slidable while engaging the side wall of the guide groove;
2. The variable valve operating apparatus according to claim 1, wherein the groove width of the guide groove is formed wider as the distance from the position near the center of the curvature circle of the slider surface increases.

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