JP4108295B2 - Variable valve mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable valve mechanism that changes a lift amount and a working angle of a valve continuously or stepwise in accordance with an operating state of an internal combustion engine.
[0002]
[Prior art]
Variable motion that changes the valve lift or operating angle continuously or stepwise according to the operating conditions of the internal combustion engine in order to achieve various characteristics such as the output, torque, fuel consumption, and exhaust gas cleanliness of the internal combustion engine. Various valve mechanisms have been considered. As one representative example, the rocker arm is swung by rotating two camshafts, and the rocker arm rocking angle is changed by relatively changing the phase of the two camshafts, so that the lift amount or action of the valve. There is known one in which the angle is continuously changed.
[0003]
[Problems to be solved by the invention]
However, in order to rotate the two camshafts as in the above representative example, the conventional drive system that has rotated one camshaft is greatly changed, and there is a problem that it is difficult to drive.
[0004]
Accordingly, an object of the present invention is to solve the above-mentioned problems and rotate a single camshaft without greatly changing the conventional drive system so that the valve lift amount, the operating angle, and the valve lift timing are continuously or An object is to provide a variable valve mechanism that can be changed in stages.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the variable valve mechanism of the present invention includes a control shaft that is pivotally supported at a small angle in the vicinity of the rocker arm, and a pressing surface that presses the cam corresponding portion of the rocker arm on the control shaft. The first intervening arm is pivotally mounted independently of the small angle rotation of the control shaft , and the control shaft is provided with a protrusion that protrudes in the radial direction of the control shaft and rotates with the control shaft at a small angle. The protrusion includes a cam sliding contact portion and a pressing portion that presses the first intervening arm at the projecting end, and the distance between the cam sliding contact portion and the pressing portion changes in the length direction of the second interposing arm. The intervening arm is pivotally mounted, and the cam sliding contact portion is pressed to press the rocker arm through the second intervening arm and the first intervening arm in this order. A single camshaft that forms a rotating cam that lifts the shaft is rotatably supported, and the control shaft and the protruding portion are rotated at a small angle within one rotation continuously or stepwise depending on the operating condition of the internal combustion engine. The swing start angle of the first intervening arm is changed by displacing the second intervening arm in the length direction by rotating, so that the contact position of the pressing surface of the first intervening arm with respect to the cam corresponding portion is changed to the first position. A lift control device is provided that changes the lift amount and working angle of the valve by the rotating cam by changing the length of the intervening arm. In addition, a cam corresponding | compatible part means the site | part corresponding to a rotating cam via a 2nd intervening arm and a 1st intervening arm, and being pressed. Further, the small angle rotation means a rotation whose rotation angle does not reach 360 degrees.
[0006]
The cam corresponding portion, the cam sliding contact portion, or the pressing portion may be a roller that can be rotated by a fixed hard chip or a rotatable member that can be rotated. However, in consideration of sliding resistance and wear, at least one (preferably any two, most preferably all) of the cam corresponding portion, the cam sliding contact portion or the pressing portion is rotatably mounted on the rocker arm. Preferably, the roller or the rotation member pivotally attached to the second interposition arm is pivotally attached to the roller or the second interposition arm.
[0007]
Examples of the control shaft include those provided with at least one projecting portion for pivotally attaching the second intervening arm. Specifically, in the length direction of the control shaft of the first intervening arm, one or two projecting portions provided on the control shaft through the opening formed in the upper portion of the first intervening arm. One having one protruding portion on one outer side or one projecting portion on both outer sides can be exemplified.
[0008]
When the roller and the rotating member are provided on the same axis, the tip of the second intervening arm and the upper portion of the rotating member are forked, the roller is sandwiched between the forks of the rotating member, and the second intervening arm You may make it a twist stress not generate | occur | produce in a 2nd interposition arm by pinching with the fork of a front-end | tip part. Alternatively, the rollers may be clamped by a fork at the tip of the second intervening arm, and these may be clamped by a fork at the top of the rotating member. In this case, the lower surface of the rotating member and the contact surface of the rotating member of the first intervening arm are formed flat so that the rotating member does not rotate and come into contact with the cam. It is desirable that the lower surface is in contact with the first intervening arm.
[0009]
The rocker arm, the first intervening arm, and the second intervening arm may oscillate in different planes, but are preferably oscillated in the same plane in terms of space efficiency.
[0010]
Here, the rocker arm may be any of the following types.
(1) A type that has a rocking center at one end of the rocker arm, a cam-corresponding portion at the center, and a valve pressing portion at the other end. (So-called swing arm)
(2) Type that has a rocking center at the center of the rocker arm, a cam corresponding part at one end, and a valve pressing part at the other end.
[0011]
The following two modes can be exemplified as the swing center portion.
(A) A mode in which the rocking center is a concave spherical surface supported by a pivot.
(B) A mode in which the rocking center portion is a shaft hole portion in which the seesaw arm is pivotally supported.
[0012]
In the aspect (a), it is preferable that a tappet clearance adjusting mechanism is provided at the center of the swing. For example, a tappet clearance adjustment mechanism in which a male screw provided on a pivot is screwed into a female screw provided on a pivot support member so that the screwing amount can be adjusted.
[0013]
Although it does not specifically limit as a lift control apparatus, The thing provided with the helical spline mechanism, the drive part using hydraulic pressure, and control apparatuses, such as a microcomputer, can be illustrated.
[0014]
The variable valve mechanism of the present invention can be applied to either the intake valve or the exhaust valve, but is preferably applied to both.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a variable valve mechanism that embodies the present invention will be described below with reference to FIGS. A swing arm type rocker arm 1 is used for this variable valve mechanism, and one end portion of the rocker arm 1 is a rocking center portion formed by supporting a concave spherical surface portion 2 formed on the same portion by a pivot 3. The other end portion of the rocker arm 1 is divided into two forks, and a valve pressing portion 4 is recessed at the lower end of each tip, and the valve pressing portion 4 presses the base end portion of the valve 5.
[0016]
A first roller 7 serving as a cam-corresponding portion is arranged in the roller arrangement hole 6 formed in the central portion of the rocker arm 1 so as to slightly protrude from the upper surface of the rocker arm 1, and the first roller 7 is orthogonal to the arm side wall. It is pivotally mounted around a rotating shaft.
[0017]
The male screw provided at the lower shaft portion of the pivot 3 is screwed into the female screw provided on the pivot support member 8 so that the screwing amount can be adjusted, thereby constituting a tappet clearance adjusting mechanism.
[0018]
A substantially cylindrical control shaft 10 is supported near the upper portion of the first roller 7 so as to be rotatable at a small angle.
[0019]
A first intervening arm 20 having a pressing surface 23 for pressing the first roller 7 is pivotally attached to the control shaft 10 so as to be able to swing independently of the small-angle rotation of the control shaft. The first intervening arm 20 includes a substantially cylindrical cylindrical portion 21 through which the control shaft 10 is inserted, and an arm portion 22 extending from the cylindrical portion 21 toward the valve pressing portion 4 side of the rocker arm 1. The first intervening arm 20 is urged in a direction in which the arm portion 22 is raised by a member (not shown).
[0020]
The lower surface of the arm portion 22 is a pressing surface 23 for pressing the first roller 7 and is formed as a concave curved surface having a radius of curvature larger than the radius of the first roller 7. Even if the contact position of the pressing surface 23 changes in the length direction of the first intervening arm 20, the pressing surface 23 presses the first roller 7 in the substantially perpendicular direction. A flat portion 24 extending in the tangential direction from the cylindrical portion 21 is formed on the upper surface of the pressing surface 23.
[0021]
An opening 25 extending in the circumferential direction from the vicinity of the boundary between the flat surface portion 24 and the cylindrical portion 21 to the vicinity of the opposite side of the control shaft 10 is provided through the upper surface of the cylindrical portion 21 of the first intervening arm 20.
[0022]
The control shaft 10 is provided with a protrusion 11 that protrudes in the radial direction of the control shaft 10 and rotates with the control shaft 10 at a small angle. The protrusion 11 penetrates the opening 25 of the first intervening arm 20, and the protrusion 11 is engaged with the opening 25, and the first interposition with respect to the protrusion 11 and the control shaft 10 is within an allowable range. The arm 20 can swing.
[0023]
At the projecting end of the projecting portion 11, a second intervening arm 30 having a second roller 34 as a cam sliding contact portion and a rotating member 33 as a pressing portion that presses the first intervening arm 20 is provided as a second intervening arm. The fork piece 31 formed at the base end portion of the 30 is pivotally mounted so as to be swingable in a state where the protruding end of the protruding portion 11 is sandwiched.
[0024]
The second roller 34 and the rotation member 33 formed in a substantially trapezoidal shape are the second roller 34 slightly protruding from the inner wall of the fork formed at the upper end of the rotation member 33 and sandwiched between the second roller 34 and the rotation member 33. The fork piece 32 formed at the distal end of the intervening arm 30 is coaxially arranged perpendicular to the inner wall of the fork piece 32 and is pivotally mounted around the shaft so as to be rotatable or rotatable. The second roller 34 and the rotation member 33 can be rotated or rotated independently of each other.
[0025]
The rotating member 33 has a flat surface at the lower end, and is a sliding portion 33a that can slide in contact with the flat surface portion 24 of the first intervening arm 20. As described above, since the first intervening arm 20 is always urged in the direction in which the arm portion 22 is raised, the rotating member 33 always abuts the sliding portion 33a against the flat portion 24. Further, the upper end side of the rotating member 33 is formed so that the second roller 34 protrudes at a wide angle so that the second roller 34 functions as a cam sliding contact portion. Accordingly, the distance between the second roller 34 and the sliding portion 33a of the rotating member 33 changes in the length direction of the second intervening arm 30 and becomes maximum at the center position of the second roller.
[0026]
A rotating cam that lifts the valve 5 by pressing the rocker arm 1 through the second interposed arm 30 and the first interposed arm 20 in this order by pressing the second roller 34 above the tip of the second interposed arm 30. A camshaft 41 that forms 40 is rotatably supported. The rotating cam 40 includes a base circle 40a, a nose gradually increasing portion 40b in which the protruding amount gradually increases, a nose 40c having the maximum protruding amount, and a nose gradually decreasing portion 40d in which the protruding amount gradually decreases.
[0027]
A lift that rotates the control shaft 10 and the projecting portion 11 at a small angle continuously or stepwise (preferably three or more stages, more preferably four or more stages) according to the operating condition of the internal combustion engine within a range of one rotation or less. A control device (not shown) is connected to the control shaft 10. When the control shaft 10 and the protrusion 11 are rotated by a small angle by the lift control device, the second intervening arm 30 is displaced in the length direction. At that time, the second roller 34 and the rotating member 33 of the second intervening arm 30 change the contact position between the rotating cam 40 and the first intervening arm 20, respectively. Change the distance. As a result, the swing angle of the first intervening arm 20 can be changed, and the contact position of the pressing surface 23 of the first intervening arm 20 with respect to the first roller 7 is set in the length direction of the first intervening arm 20. By changing it, the lift amount and operating angle of the valve 5 by the rotating cam 40 are changed.
[0028]
In the lift control device, for example, a piston provided with a helical spline moves in the axial direction while rotating by a predetermined angle by hydraulic pressure, and the rotation causes the control shaft 10 to rotate by a small angle, thereby reducing the rising angle of the protrusion 11 by one. It has a structure that changes within a range of rotation, and is controlled by a control device such as a microcomputer based on a detection value from a rotation sensor of an internal combustion engine, an accelerator opening sensor, or the like.
[0029]
With the above configuration, in the variable valve mechanism according to the present embodiment, when the rotating cam 40 presses the second roller 34, the second intervening arm 30 swings around the shaft-attached portion with the protruding portion 11 and rotates. When the member 33 presses the first intervening arm 20 while changing the contact position between the sliding portion 33a and the flat surface portion 24, the first interposing arm 20 swings, and the first interposing arm 20 is connected to the first roller 7. The rocker arm 1 is swung and the valve 5 is lifted by pressing the first roller 7 with the pressing surface 23 while changing the abutting position.
[0030]
Further, at this time, by rotating the control shaft 10 by a small angle, the second intervening arm 30 acts to move the rotating cam 40 and the first intervening arm 20 away by the second roller 34 and the rotating member 33. At this time, the first intervening arm 20 swings in the direction in which the arm portion 22 is lowered, so that the swing start angle of the first intervening arm 20 can be changed. Then, the contact position of the first intermediate arm 20 with respect to the first roller 7 changes in the length direction of the first intermediate arm 20, specifically, when the swing start angle of the first intermediate arm 20 is high, the first roller 7 is the base end side of the cylindrical portion 21 or the arm portion 22, and when the swing start angle of the first intervening arm 20 is low, the contact position of the first roller 7 is the distal end side of the arm portion 22.
[0031]
The variable valve mechanism configured as described above operates as follows.
First, FIG. 3 (a) → (b) shows the position of the protruding portion 11 and its action under an operating condition where the maximum lift amount and the maximum operating angle are required.
As shown in FIG. 3 (a), the second roller 34 and the rotating member 33 are maximum between the rotating cam 40 and the first intervening arm 20 under an operating condition that requires the maximum lift amount and the maximum operating angle. It is controlled to be in a limited state. Therefore, the swing start angle of the first intervening arm 20 when the second roller 34 is in sliding contact with the base circle 40a of the rotating cam 40 is the lowest. At this time, since the first roller 7 is in contact with the cylindrical portion 21 of the first intervening arm 20 and the first roller 7 is at the uppermost position, the valve 5 is not lifted. However, since the contact position of the first roller 7 is close to the pressing surface 23, the contact position of the first roller 7 quickly shifts to the pressing surface 23 when the first intervening arm 20 starts to swing. Then, the rocker arm 1 is pushed and the valve 5 is lifted.
As shown in FIG. 3B, when the second roller 34 is pressed by the nose 40c via the nose gradually increasing portion 40b, the rotating member 33 always moves the sliding portion 33a to the plane portion of the first intervening arm 20. Since the first intervening arm 20 is pressed in a state of being in contact with 24, the rotating member 33 presses the first intervening arm 20 while rotating with respect to the second intervening arm 30. Also swings around the pivoted portion at the upper end of the protruding portion 11 and allows the second roller 34 to be displaced downward. At this time, the first intervening arm 20 swings to the maximum, the contact position of the first interposing arm 20 with respect to the first roller 7 shifts from the cylindrical portion 21 to the tip of the pressing surface 23, and the rocker arm 1 swings to the maximum pressing position. As a result, the lift amount L of the valve 5 is generated and increased to reach the maximum value Lmax, and the operating angle is also maximized.
As described above, even if the abutment position is changed, the pressing surface 23 formed in the concave curved surface presses the first roller 7 in the substantially perpendicular direction, so that the first intervening arm 20 is moved in the length direction. A stress component is hardly generated, and no load is applied between the cylindrical portion 21 and the control shaft 10.
[0032]
Next, FIG. 4 (a) → (b) shows the position of the protrusion 11 and the operation due to the position under an operating condition that requires a minute lift amount and a minute working angle.
As shown in FIG. 4A, the second roller 34 and the rotating member 33 are greatly increased from between the rotating cam 40 and the first intervening arm 20 under an operating condition that requires a small lift amount and a small working angle. It is controlled to be in a separated state. Therefore, the swing start angle of the first intervening arm 20 when the second roller 34 is in sliding contact with the base circle 40a of the rotating cam 40 is near the uppermost position. At this time, since the first roller 7 is in contact with the cylindrical portion 21 of the first intervening arm 20 and the first roller 7 is at the uppermost position, the valve 5 is not lifted.
As shown in FIG. 4B, when the second roller 34 is pressed by the nose 40c through the nose gradually increasing portion 40b, the second roller 34 is far away from the control shaft 10 and the camshaft 41. The amount of pressure on the first intervening arm 20 is smaller than that in FIG. 3B, and the amount of rocking of the first intervening arm 20 is also reduced. At this time, since the contact position of the first intervening arm 20 with respect to the first roller 7 is slightly shifted from the cylindrical portion 21 to the pressing surface 23, the pressing amount of the first roller 7 becomes very small, and the lift amount L of the valve 5 is reduced. Both the working angles are very small (see FIG. 6).
[0033]
Note that, in an operating situation where an intermediate lift amount / working angle between FIG. 3 and FIG. 4 is required, the intermediate protrusion 11 angle between FIG. 3 and FIG. As a result, intermediate lift / working angles can be obtained continuously or stepwise as shown in FIG.
[0034]
Next, FIGS. 5 (a) → (b) show the position of the protruding portion 11 and the action due to the operation under the condition that the lift stop is necessary.
As shown in FIG. 5 (a), the second roller 34 and the rotating member 33 are separated from the rotating cam 40 and the first intervening arm 20 as much as possible under an operating condition that requires lift suspension. The rising angle of the protrusion 11 is controlled so as to be. Accordingly, the swing start angle of the first intervening arm 20 when the second roller 34 is in sliding contact with the base circle 40a of the rotating cam 40 is at the uppermost position. At this time, since the first roller 7 is in contact with the cylindrical portion 21 of the first intervening arm 20 and the first roller 7 is at the uppermost position, the valve 5 is not lifted.
As shown in FIG. 5B, when the second roller 34 is pressed by the nose 40c through the nose gradually increasing portion 40b, the second roller 34 is farthest from the control shaft 10 and the camshaft 41. Therefore, the pressing amount to the first intervening arm 20 is further smaller than that in FIG. 4B, and the swinging amount of the first interposing arm 20 is also minute. At this time, the contact position of the first intervening arm 20 with respect to the first roller 7 moves from the cylindrical portion 21 toward the pressing surface 23, but remains on the cylindrical portion 21, so that the pressing amount of the first roller 7 becomes 0 and the valve 5 Becomes a lift rest state.
[0035]
Next, a second embodiment of the variable valve mechanism embodying the present invention will be described with reference to FIG. 7 only for parts different from the first embodiment. FIG. 7 shows that the control shaft 10 is provided with a protrusion 11 that does not penetrate the first intervening arm 20 with respect to the variable valve mechanism of the first embodiment.
[0036]
In the first embodiment, one protrusion 11 is provided on the control shaft 10 through the opening 25 formed in the first intervening arm 20. However, in the present embodiment, one protrusion 11 is provided on both sides of the first intervening arm 20. Projections 11 are provided one by one. Since the length of the projecting portion 11 is shortened so as to make the whole mechanism small, the relief surface 26 for escaping the contact of the proximal end portion of the second intervening arm 30 to the first intervening arm 20 is provided in the first intervening arm 20. Is formed.
[0037]
In the first embodiment, the protrusion 11 is sandwiched by the fork piece 31 formed at the base end of the second intervening arm. However, in this embodiment, the two protrusions 11 provided on the control shaft 10 are the second protrusion 11. Since the intervening arm 30 is sandwiched, the base end portion of the second intervening arm 30 does not need to be formed in a fork shape and serves as the shaft mounting portion 35.
[0038]
In the first embodiment, since the protrusion 11 is engaged with the opening 25, the protrusion 11 regulates the swingable range of the first intervening arm 20. However, in the present embodiment, the first intervening arm 20 is formed by the protrusion 11. It is easy to design the mechanism because it is not restricted by the swingable range.
[0039]
Next, a third embodiment of the variable valve mechanism embodying the present invention will be described with reference to FIG. 8 only for parts different from the second embodiment. FIG. 8 is obtained by removing the second roller 34 from the variable valve mechanism of the second embodiment.
[0040]
In the second embodiment, the second roller 34 as the cam sliding contact portion is pivotally mounted so as to protrude from the tip of the second intervening arm 30. However, the second intervening arm 30 of the present embodiment is a fork piece. A cam slide contact surface 36 that is pressed by the rotary cam 40 is formed on the upper side of 32. The cam sliding contact surface 36 is formed so as to move away from the second interposed arm 30 as it approaches the distal end from the proximal end of the second interposed arm 30.
[0041]
Since the second roller 34 is omitted, the number of parts can be reduced. Further, the rotating member 33 does not need to form a fork for sandwiching the second roller 34 at its upper end.
[0042]
In addition, this invention is not limited to the structure of the said embodiment, For example, as follows, it can also change and actualize in the range which does not deviate from the meaning of invention.
(1) Change the configuration and control method of the lift control device as appropriate.
(2) Use a rocker arm with a rocking center at the center.
(3) The pressing portion is a rotatable roller.
(4) The pressing portion and the cam sliding contact portion are provided on different axes.
(5) A pressing portion and a cam sliding contact portion are provided on the same axis.
[0043]
【The invention's effect】
Since the variable valve mechanism of the present invention is configured as described above, the lift amount and operating angle of the valve are continuously or stepwise rotated by rotating a single camshaft without greatly changing the conventional drive system. It has an excellent effect of being able to change it.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a variable valve mechanism according to a first embodiment of the present invention.
FIG. 2 is a perspective view showing a state in which a cam shaft and a rotating cam of the variable valve mechanism are omitted and a second intervening arm is removed from a protruding portion.
FIG. 3 is a cross-sectional view showing the operation of the mechanism when the maximum lift amount and operating angle in FIG. 1 are required.
FIG. 4 is a cross-sectional view showing the operation of the mechanism when the minute lift amount / operation angle shown in FIG. 1 is required.
FIG. 5 is a cross-sectional view showing the operation of the mechanism when the lift stop of FIG. 1 is necessary.
FIG. 6 is a graph showing a lift amount and a working angle of a valve obtained by the same mechanism.
FIG. 7 is a perspective view showing a state in which a camshaft and a rotating cam of a variable valve mechanism according to a second embodiment of the present invention are omitted and a second intervening arm is removed from a protruding portion.
FIG. 8 is a perspective view showing a state where a camshaft and a rotating cam of a variable valve mechanism according to a third embodiment of the present invention are omitted and a second intervening arm is removed from a protruding portion.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rocker arm 5 Valve | bulb 7 The 1st roller 20 as a cam corresponding part The 1st interposition arm 10 The control shaft 22 The arm part 23 The press part 24 The flat part 25 The opening part 11 The protrusion part 30 The 2nd interposition arm 33 The rotation member 34 as a press part Second roller 40 as cam sliding contact portion Rotating cam 41 Cam shaft

Claims (4)

A control shaft is supported in the vicinity of the rocker arm so that it can rotate at a small angle,
Wherein the control shaft, and independently rotatably attached swingably to the first intermediate arm small angular rotation of said control shaft having a pressing surface for pressing the cam corresponding portion of the rocker arm,
The control shaft is provided with a protrusion that small angular rotation together with the control shaft and protrudes in the radial direction of the control shaft,
The projecting end of the projecting portion, and a pressing portion that presses the first intermediate arm and the cam sliding portion, the distance between the cam sliding portion and the pressing portion is changed in the length direction of the second intermediate arm Attaching two intervening arms so that they can swing,
A single camshaft, which forms a rotating cam that lifts the valve by pressing the rocker arm through the second intervening arm and the first interposing arm in this order by pressing the cam sliding contact portion, is rotatably supported. And
The first intervening arm is displaced in the longitudinal direction by rotating the control shaft and the projecting portion by a small angle within a range of one rotation continuously or stepwise according to the operating condition of the internal combustion engine. By changing the swing start angle of the intervening arm and changing the contact position of the pressing surface of the first intervening arm with respect to the cam corresponding portion in the length direction of the first intervening arm, the lift amount and working angle of the valve by the rotating cam A variable valve mechanism provided with a lift control device that changes the valve.   At least one of the cam corresponding portion, the cam sliding contact portion, and the pressing portion is a roller rotatably attached to the rocker arm, a roller rotatably attached to the second intervening arm, or a first roller 2. The variable valve mechanism according to claim 1, wherein the variable valve mechanism is a pivot member pivotally attached to the two intervening arms. The variable valve mechanism according to claim 1 or 2, wherein an opening is provided through the first intervening arm, and the protrusion is provided through the opening. 3. The variable valve mechanism according to claim 1, wherein the protrusions are provided one by one on both outer sides in the length direction of the control shaft of the first intervening arm.

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