JP2013170488A - Rocker arm - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent excessive shaft reaction from being applied from a rocker shaft both to an input arm and an output arm.SOLUTION: In a rocker arm comprising an input arm 30 including an input roller 34 in abutment with a driving cam 10, an output arm 40 including an output plane 47 in abutment with a valve 7, and coupling pins 51 and 52 having both arms 30 and 40 coupled, the coupling pins 51 and 52 are disposed such that a coupling line C connecting between the center of the coupling pins 51 and 52 and the center of a rocker shaft 20 is located in a lateral view within a range R of ±25 degrees from a bisector M which bisects an input/output angle θ between an input line A connecting between the rotation center of the input roller 34 and the center of the rocker shaft 20 in a lateral view and an output line B connecting between the center of the output plane 47 and the center of the rocker shaft 20 in a lateral view.

Description

  The present invention relates to a seesaw-type rocker arm (seesaw arm) that, when a rear end is pressed by a drive cam, swings an intermediate portion in the length direction about an axis (swing center) and drives a valve at the tip.

  In this type of seesaw type rocker arm, rocker shaft 20 is swung like switchable rocker arm 90a of conventional example 1 shown in FIG. 8 and switchable rocker arm 90b of conventional example 2 shown in FIG. An input arm 91 provided with an input roller 92 rotatably supported on the drive cam 10 at the rear end portion and pivotally supported on the rocker shaft 20 next to the input arm 91. At the same time, there is an output arm 93 that swings with the input arm 91 and drives the valve 7 with the output surface 94 at the distal end when connected to the input arm 91 with a connecting pin 95.

  In such switchable rocker arms 90a and 90b (seesaw arm), the connecting pin 95 is located on the rear end side (on the input roller 92 side) with respect to the center of swinging, like the rocker arm 90a of the first conventional example shown in FIG. Or in the case of the rocker arm 90b of the second conventional example shown in FIG.

JP 2006-132378 A JP 2003-49622 A

  In the switchable rocker arm 90a of the first conventional example shown in FIG. 8, in the input arm 91, as shown in FIG. 8B, both the input roller 92 and the connecting pin 95 are closer to the rear end side than the swing center. Because of the provided relationship, the input side driving force Fa applied by the drive cam 10 to the input arm 91 via the input roller 92 and the pin reaction force Fc applied by the output arm 93 to the input arm 91 via the connecting pin 95 are: , Face each other and cancel each other. Therefore, the input-side shaft reaction force Fo applied to the input arm 91 by the rocker shaft 20 as a reaction force against the resultant force (that is, the bending moment applied to the input arm 91 around the rocker shaft 20) is relatively small.

  However, in the output arm 93, as shown in FIG. 8C, the output surface 94 is provided on the front end side with respect to the swing center, and the connection pin 95 is provided on the rear end side with respect to the swing center. The output side driving force fc that the input arm 91 applies to the output arm 93 via the connecting pin 95 and the valve reaction force fb that the valve 7 (valve spring 8) applies to the output arm 93 are centered on the oscillation center. The front end side and the rear end side of the sandwich are directed in the same direction and strengthened. Therefore, the output side shaft reaction force fo applied to the output arm 93 by the rocker shaft 20 as a reaction force against the resultant force (that is, the bending moment applied to the output arm 93 around the rocker shaft 20) becomes relatively large. .

  Therefore, in the case of a high output engine, etc., there is anxiety about the strength against the bending moment of the output arm 93, and when the rigidity with respect to the bending moment of the output arm 93 is insufficient, the engine performance due to lift loss, abnormal motion, etc. This may lead to a decrease in

  On the other hand, in the switchable rocker arm 90b of the conventional example 2 shown in FIG. 9, in the output arm 93, as shown in FIG. The output side driving force fc that the input arm 91 applies to the output arm 93 via the connecting pin 95 and the valve reaction force fb that the valve 7 (valve spring 8) applies to the output arm 93 are provided. And opposite each other at the same tip side. Therefore, the output side shaft reaction force fo applied to the output arm 93 by the rocker shaft 20 as a reaction force against the resultant force (that is, the bending moment applied to the output arm 93 around the rocker shaft 20) is relatively small.

  However, in the input arm 91, as shown in FIG. 9B, the input roller 92 is provided on the rear end side with respect to the swing center, and the connection pin 95 is provided on the front end side with respect to the swing center. In addition, the input side driving force Fa applied by the drive cam 10 to the input arm 91 and the pin reaction force Fc applied by the output arm 93 to the input arm 91 via the connecting pin 95 are on the rear end side across the oscillation center. And pointed in the same direction on the tip side and strengthened. Therefore, the input shaft reaction force Fo applied to the input arm 91 by the rocker shaft 20 as a reaction force against the resultant force (that is, the bending moment applied to the output arm 93 around the rocker shaft 20) is relatively large. .

  Therefore, in the case of a high output engine, etc., there is anxiety about the strength against the bending moment of the input arm 91, and when the rigidity with respect to the bending moment of the input arm 91 is insufficient, the engine performance due to lift loss, abnormal motion, etc. This may lead to a decrease in

  Accordingly, an object is to prevent an excessive shaft reaction force (that is, an excessive bending moment about the rocker shaft) from being applied to the input arm and the output arm from the rocker shaft.

  In order to achieve the above object, a rocker arm according to the present invention includes an input arm that includes an input roller that is pivotally supported by a rocker shaft and rotatably abuts on a drive cam, and the input arm is adjacent to the input arm. It is pivotally supported on the rocker shaft and is connected to the input arm with a connecting pin. When connected, the input arm swings with the input arm to drive the valve on the output surface. An input / output angle that is an inferior angle between an input line that connects the rotation center of the roller and the center of the rocker shaft and an output line that connects the center of the output surface and the center of the rocker shaft in a side view. In the rocker arm that is 120 degrees or more at the time of the connection, a connection line that connects the center of the connection pin and the center of the rocker shaft in a side view bisects the entrance / exit angle at the time of the connection. From bisector, characterized in that a said connecting pin so as to be located within a range of ± 25 degrees at the center angle of the rocker shaft.

  Here, the entrance / exit angle is more preferably 130 degrees or more, and still more preferably 140 degrees or more. This is because the drive cam (camshaft) can be arranged at a position away from the valve as the angle increases.

  Further, the position of the connecting line is more preferably within a range of ± 20 degrees from the bisector at the central angle of the rocker shaft, further preferably within a range of ± 15 degrees, and ± 10 Most preferably within the range of degrees. This is because the closer to the bisector, the higher the effect that can be expected.

  The length of the connecting line is not particularly limited, but is 0.5 to 1.2 times the length of the input line and 0.5 to 1.2 times the length of the output line. It is preferable that The longer the length, the smaller the amount of force applied to the connecting pin, the smaller the length of the input arm and the output arm, or the shape becomes distorted. Because.

  According to the present invention, the connecting line is positioned so that the connecting line is located near the bisector (in the range of ± 25 degrees as the central angle of the rocker shaft) obtained by dividing the input / output angle between the input line and the output line into two. Since the pin is arranged, the output shaft reaction force that the rocker shaft applies to the output arm as in the case where the connecting line is located closer to the input line (in the case of the conventional example 1) (that is, the output arm around the rocker arm) The bending moment that is applied to the input arm, ie, the rocker shaft is applied to the input arm as in the case where the connecting line is positioned more than the output line (in the case of the conventional example 2). The bending moment applied to the input arm around the center is not excessively large. Therefore, an excessive shaft reaction force is not applied to the input arm and the output arm from the rocker shaft.

It is a side view which shows the variable valve mechanism of an Example. It is a perspective view which shows the variable valve mechanism of an Example. It is a disassembled perspective view which shows the variable valve mechanism of an Example. (A) is front sectional drawing which shows the time of connection of the variable valve mechanism of an Example, (b) is front sectional drawing which shows the time of non-connection of the variable valve mechanism of an Example. (A) is a side view which shows the time of connection of the variable valve mechanism of an Example, (b) is a side view which shows the time of non-connection of the variable valve mechanism of an Example. It is a side view which shows balance of the force added to the rocker arm of an Example. (A) is side sectional drawing which shows the balance of the force added to the input arm of an Example, (b) is side sectional drawing which shows the balance of the force added to the output arm of an Example. (A) is a side view which shows the balance of the force added to the rocker arm of the prior art example 1, (b) is side sectional drawing which shows the balance of the force added to the input arm of the prior art example 1, (c) FIG. 10 is a side sectional view showing a balance of forces applied to the output arm of Conventional Example 1. (A) is a side view which shows the balance of the force added to the rocker arm of the prior art example 2, (b) is a side sectional view which shows the balance of the force applied to the input arm of the prior art example 2, (c) FIG. 10 is a side sectional view showing a balance of forces applied to the output arm of Conventional Example 2.

  The variable valve mechanism 9 of this embodiment shown in FIGS. 1 to 7 presses a single valve 7 attached to a cylinder head (not shown) against the restoring force of the valve spring 8 to press the valve 7. It is a mechanism which drives. The variable valve mechanism 9 includes a drive cam 10, a rocker shaft 20, an input arm 30, an output arm 40, a coupling mechanism 50, a hydraulic mechanism 60, and a lost motion mechanism 70, which will be described below. Has been. The input arm 30, the output arm 40, and the coupling mechanism 50 constitute a switchable rocker arm. Hereinafter, one of the rocker shafts 20 in the axial direction is referred to as the right and the other is referred to as the left, but the right and the left may be opposite.

[Drive cam 10]
The drive cam 10 is a member for driving the valve 7 and is formed integrally with a camshaft 15 that rotates as the internal combustion engine rotates. The drive cam 10 includes a base circle 11 having a true circular cross section and a cam nose 12 protruding from the base circle 11.

[Rocker shaft 20]
The rocker shaft 20 is a pipe-like shaft extending in the left-right direction for supporting the input arm 30 and the output arm 40 so as to be swingable, and a shaft oil passage 21 is formed inside the pipe. A hydraulic hole 23 communicating with the shaft oil passage 21 is provided in the outer peripheral surface of the rocker shaft 20 that supports the input arm 30, and the outer peripheral surface of the portion that supports the output arm 40 is provided in the outer peripheral surface. A lubricating hole 24 communicating with the shaft oil passage 21 is provided therethrough.

[Input arm 30]
The input arm 30 includes a pair of left and right outer arm portions 31, 31 arranged in parallel in the left-right direction, a roller shaft 33 that connects the rear end portions of the pair of left and right outer arm portions 31, and an upper end portion. The upper connection part 35 which connected mutually and the lower side connection part 37 which connected lower end parts are comprised. And the rocking | fluctuation center holes 32 and 32 for penetrating the rocker shaft 20 are penetrated by the front-end | tip part of a pair of left and right outer arm parts 31 and 31, respectively. An input roller 34 that abuts on the drive cam 10 is rotatably supported on the roller shaft 33 at the rear end. Further, a lost motion abutting protrusion 36 that abuts on the lost motion mechanism 70 is provided on the upper connecting portion 35. In addition, the input arm 30 is improved in a cantilever load by integrating the pair of left and right outer arm portions 31, 31 in this way.

[Output arm 40]
The output arm 40 is an inner arm provided between the pair of left and right outer arm portions 31, 31, and a swing center hole 42 through which the rocker shaft 20 is inserted penetrates the rear end portion in the left-right direction. An output portion 43 that abuts against the valve 7 is provided at the tip portion. The output portion 43 is attached to an output hole 44 that is attached to a front end portion of the output arm 40 in a vertical direction and protrudes downward, and a circular lower end portion of the output shaft 44 in a side view. The output lifter 46 is mounted so as to be rotatable in the circumferential direction, and an output surface 47 is formed on the lower surface of the output lifter 46. Further, inside the output arm 40, a lubricating oil passage 48 for sending oil from the lubricating hole 24 of the rocker shaft 20 to the output portion 43 is provided.

[Coupling mechanism 50]
The connection mechanism 50 is a mechanism for connecting the input arm 30 and the output arm 40 so that the connection can be released. The connection mechanism 50 includes a first connection pin 51 provided to be displaceable between a left connection position straddling between the right outer arm portion 31 and the output arm 40 and a right non-connection position not straddling, A second connection pin 52 provided so as to be displaceable between a left connection position straddling between the output arm 40 and the left outer arm portion 31 and a right non-connection position without straddling, and the first connection pins 51 And a return spring 56 that presses the second connecting pin 52 toward the left connecting position.

  Specifically, the first connection pin 51 is inserted into a first connection hole 53 that penetrates the outer arm portion 31 on the right side of the input arm 30. The first connecting hole 53 and the second connecting hole 54 penetrating the output arm 40 are displaceable between a left connecting position and a right unconnecting position that does not straddle. . The second connecting pin 52 is inserted into the second connecting hole 54 described above, and the left side straddling between the second connecting hole 54 and the third connecting hole 55 formed in the left outer arm portion 31 in a recessed manner. It is possible to displace between the connected position and the unconnected position on the right side without straddling. A retainer 57 is attached to an opening on the right side (opposite side of the output arm 40 side) of the first connection hole 53, and the return spring 56 has an end surface on the right side of the retainer 57 and the first connection pin 51. It is attached between.

  Here, the dimensions and shape of the switchable rocker arm composed of the input arm 30, the output arm 40 and the coupling mechanism 50 will be described. The input connecting the rotation center of the input roller 34 and the center of the rocker shaft 20 in a side view. The length of the line A (line segment) is about 35 to 40 mm, and the length of the output line B connecting the center of the output surface 47 and the center of the rocker shaft 20 in a side view is about 45 to 50 mm. It has become. The input / output angle θ, which is the angle on the minor angle (180 degrees or less) side between the input line A and the output line B, is 140 to 160 when the input arm 30 and the output arm 40 are connected. It is a measure. In addition, the length of the connecting line C connecting the centers of the connecting pins 51 and 52 and the center of the rocker shaft 20 in a side view is about 25 to 30 mm, and the connecting line C has an input / output angle θ when connected. It is located in the vicinity of a bisector M divided into two (in the range of ± 10 degrees from the bisector M to the central angle of the rocker shaft 20). Therefore, the connecting line C is always located within a range R of ± 25 degrees from the bisector M at the central angle of the rocker shaft 20 as shown in FIG. The angle α between the input line A and the connecting line C at the time of connection is about 70 to 80 degrees, and the angle β between the output line B and the connecting line C at the time of connection is It is about 70 to 80 degrees.

[Hydraulic mechanism 60]
The hydraulic mechanism 60 is a mechanism for driving the first connecting pin 51 and the second connecting pin 52 between the left connection position and the right non-connection position. The hydraulic mechanism 60 includes a hydraulic chamber 61 in which the opening on the right side of the third connecting hole 55 is closed by a hydraulic pin 62, and a left side for sending hydraulic pressure from the hydraulic hole 23 of the rocker shaft 20 to the hydraulic chamber 61. And a hydraulic path 63 provided in the outer arm portion 31.

[Lost motion mechanism 70]
The lost motion mechanism 70 is a mechanism for causing the input arm 30 to swing following the drive cam 10 even when the input arm 30 and the output arm 40 are disconnected. The lost motion mechanism 70 includes a cylindrical body 71 fixed to a cylinder head (not shown) via an attachment portion 72, a retainer 73 attached to the upper end portion of the body 71, and an upper end portion by the retainer 73. And a lost motion lifter 76 that is attached to the lower end portion of the lost motion spring 75 and abuts on the lost motion abutment protrusion 36 of the input arm 30.

  The function of the variable valve mechanism 9 described above is as follows: {1} When the input arm 30 and the output arm 40 are connected to drive the valve 7 (when connected), and {2} the connection is released In the following, description will be made separately for the resting state (when not connected) in which the valve 7 is stopped.

{1} When driving (when connected)
As shown in FIG. 4A, when the valve 7 is driven, the first connecting pin 51 and the second connecting pin 52 are respectively moved by the restoring force of the return spring 56 as the hydraulic pressure in the hydraulic chamber 61 decreases. Driven to the left connection position. Thereby, the input arm 30 and the output arm 40 are connected, and the output arm 40 swings together with the input arm 30 to open and close the valve 7 as shown in FIG.

{2} When in hibernation (when disconnected)
In the rest state in which the driving of the valve 7 is stopped, as shown in FIG. 4B, the hydraulic pressure in the hydraulic chamber 61 is increased, so that the first connecting pin 51 and the second connecting pin 52 are moved by the return spring 56. It is driven to the unconnected position on the right side against the restoring force. As a result, the connection between the input arm 30 and the output arm 40 is released, and as shown in FIG. 5B, the output arm 40 is stationary and only the input arm 30 is pressed against the drive cam 10 and the lost motion mechanism 70. To be missed.

  According to the present embodiment, since the angle α between the input line A and the connection line C at the time of connection is about 70 to 80 degrees, the input applied by the drive cam 10 to the input arm 30 is input to the input arm 30. The side driving force Fa and the pin reaction force Fc that the output arm 40 applies to the input arm 30 via the connecting pins 51 and 52 face each other to some extent and cancel each other. Therefore, the input side shaft reaction force Fo applied to the input arm 30 by the rocker shaft 20 as a reaction force against the resultant force (Fa + Fc) (that is, the bending moment applied to the input arm 30 around the rocker shaft 20) is excessively large. Never become. Therefore, the input shaft reaction force Fo (bending moment applied to the input arm 30) compared to the case where the angle α between the input line A and the connecting line C is larger than about 70 to 80 degrees (in the case of the conventional example 2). As a result, the durability of the input arm 30 can be improved, and the occurrence of lift loss due to insufficient rigidity of the input arm 30 can be reduced to stabilize the engine performance.

  Further, since the angle β between the input / output line B and the connection line C at the time of connection is about 70 to 80 degrees, the input arm 30 is connected to the output arm via the connection pins 51 and 52 in the output arm 40. The output side driving force fc applied to 40 and the valve reaction force fb applied by the valve 7 to the output arm 40 face each other and cancel each other to some extent. Therefore, the output-side shaft reaction force fo (that is, the bending moment applied to the output arm 40 around the rocker shaft 20) applied to the output arm 40 by the rocker shaft 20 as a reaction force against the resultant force (fc + fb) is excessively large. Never become. Therefore, the output side shaft reaction force fo (bending moment applied to the output arm 40) compared to the case where the angle β between the output line B and the connecting line C is larger than about 70 to 80 degrees (in the case of Conventional Example 1). As a result, the durability of the output arm 40 can be improved, and the occurrence of lift loss due to insufficient rigidity of the output arm 40 can be reduced to stabilize the engine performance.

  Therefore, excessive shaft reaction forces Fo and fo are not applied to the input arm 30 and the output arm 40 from the rocker shaft 20, and therefore, it is possible to deal with a high load engine.

  In addition, this invention is not limited to the structure of the said Example, It can also change and embody in the range which does not deviate from the meaning of invention.

7 Valve 10 Driving cam 20 Rocker arm 30 Input arm 34 Input roller 40 Output arm 47 Output surface 51 First connecting pin 52 Second connecting pin A Input line B Output line C Connecting line θ I / O angle M 2 Equivalent line R 2 Equivalent line ± 25 degrees range from line

Claims (2)

An input arm (30) having an input roller (34) pivotally supported on the rocker shaft (20) and rotatably abutting on the drive cam (10), next to the input arm (30) When connected to the rocker shaft (20) so as to be swingable and connected to the input arm (30) by connecting pins (51, 52), the input arm (30) swings with the output arm (30). 47) and an output arm (40) for driving the valve (7).
The input line (A) connecting the rotation center of the input roller (34) and the center of the rocker shaft (20) in a side view, and the center of the output surface (47) and the rocker shaft (20) in a side view. In the rocker arm where the angle of entry / exit (θ), which is the angle on the minor angle side with the output line (B) connecting the center, is 120 degrees or more at the time of the connection
A connecting line (C) connecting the center of the connecting pin (51, 52) and the center of the rocker shaft (20) in a side view is divided into two equal parts by dividing the entrance / exit angle (θ) into two at the time of the connection. The rocker arm, wherein the connecting pins (51, 52) are arranged so as to be located within a range (R) of ± 25 degrees from a line (M) to a central angle of the rocker shaft (20).   The length of the connecting line (C) is 0.5 to 1.2 times the length of the input line (A), and 0.5 to 1 .5 of the length of the output line (B). The rocker arm according to claim 1, wherein the rocker arm is doubled.

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