JP4046487B2 - 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 to lift the valve lift. A device in which the amount or the working angle is continuously changed is known. In addition, there is known one that sub-lifts a valve by adding a minute nose to a cam.
[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 the one camshaft is greatly changed, and there is a problem that driving is difficult. . Further, since the sublift amount cannot be changed, it is impossible to control the internal EGR.
[0004]
Accordingly, an object of the present invention is to solve the above-mentioned problems and rotate one camshaft without greatly changing the conventional drive system to continuously or stepwise adjust the main lift amount, sublift amount and working angle of the valve. It is an object of the present invention to provide a variable valve mechanism that makes it possible to optimally control the internal EGR and improve fuel efficiency.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the variable valve mechanism according to the present invention has a seesaw arm pivotally attached to a cam-corresponding part of a rocker arm so that the seesaw arm can swing at the center thereof, and a first slider is respectively attached to one end and the other end of the seesaw arm. One camshaft having a contact portion and a second slidable contact portion, and forming a first rotary cam that presses the first slidable contact portion above the first slidable contact portion and a second rotary cam located adjacent thereto And an intermediate member that interacts with the second rotary cam and acts on the second sliding contact portion is provided above the second sliding contact portion so as to be displaceable. At least one of the intervening members is formed to generate a valve sub-lift and a main lift following the sub-lift, and the amount of action of the second sliding contact portion by the intervening member is continuously changed according to the operating state of the internal combustion engine. Or install a relative angle control device that changes step by step. It is characterized in that was. The cam-corresponding portion means a portion that corresponds to the cam via the seesaw arm and is pressed. Further, the small angle rotation means a rotation whose rotation angle does not reach 360 degrees.
[0006]
As the interposition member, a control cam provided with a protruding portion that presses the second slidable contact portion of the seesaw arm and an intervening arm provided with the slidable contact portion pressed by the second rotating cam are coupled so that the relative angle can be changed. In addition, an example in which a single support shaft is rotatably mounted at a small angle can be exemplified.
[0007]
As the interposition member, a control cam having a concave surface that works so as to allow the second sliding contact portion of the seesaw arm to enter and escape and an intervening arm provided with an intervening sliding contact portion pressed by the second rotating cam are relative to each other. An example is one that is coupled so as to be capable of changing the angle and is attached to one support shaft so as to be capable of rotating at a small angle.
[0008]
The first rotating cam and the second rotating cam are interposed so that the second rotating cam lifts the valve via the interposition member at a timing different from the timing at which the first rotating cam presses the first sliding contact portion and lifts the valve. A member formed with a member can be exemplified. More specifically, the nose of the second rotating cam is formed at a position preceding the nose of the first rotating cam, and before the first rotating cam presses the first sliding contact portion and main lifts the valve, An example is one in which the two-turn cam displaces the interposition member and the interposition member acts on the second sliding contact portion to cause the valve to sub-lift.
[0009]
One (or both) of the first rotating cam and the second rotating cam can be exemplified by a sub nose and a main nose following the sub nose.
[0010]
The interposed sliding contact portion may be a fixed hard tip or a rotatable roller. However, considering the sliding resistance and wear between the sliding portion and the cam, it is preferable that the intervening sliding contact portion has a roller rotatably mounted on the intervening arm.
[0011]
The first cam sliding contact portion and the second cam sliding contact portion may be a fixed hard tip or a rotatable roller. However, considering the sliding resistance and wear between the sliding portion and the cam, at least one of the first cam sliding contact portion and the second cam sliding contact portion (preferably both) can rotate the roller to the seesaw arm. It is preferable to be attached to the shaft.
[0012]
The relative angle control device is not particularly limited, and examples include a device including a helical spline mechanism, a drive unit using hydraulic pressure, and a control device such as a microcomputer.
[0013]
Although the rocker arm and the seesaw arm may swing in different planes, it is preferable that the rocker arm and the seesaw arm swing in the same plane in terms of space efficiency.
[0014]
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.
[0015]
When the rocker arm and the seesaw arm swing in the same plane, the present invention is preferably embodied in the above type (1) because the seesaw arm does not protrude from the rocker arm and has good space efficiency. That is, the rocker arm is a type that has a rocking center at one end, a cam corresponding portion at the center, and a valve pressing portion at the other end, and the seesaw arm is pivotally attached to the cam corresponding portion. Is preferred.
[0016]
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.
[0017]
In the aspect (a), it is preferable that a tappet clearance adjusting mechanism is provided between the swing center portion and the adjuster. For example, in the above aspect (a), a tappet clearance adjustment mechanism can be exemplified in which a male screw provided on the pivot is screwed into a female screw provided on the pivot support member so that the screwing amount can be adjusted.
[0018]
In the aspect in which the concave curved surface is provided in the control cam, it is preferable that an adjuster for preventing a gap from being formed between each roller and the cam is provided at the center of the swing. The structure of the adjuster is not particularly limited, and includes an inner member engaged so as to be able to contact and separate, a bottomed hole formed in the cylinder head, and a lost motion spring that urges the inner member and the bottomed hole in the separation direction. A mechanical adjuster (mechanical adjuster) can be exemplified. More specifically, a cup-shaped inner member whose side peripheral walls engage with each other on the opening side, a bottomed hole formed in the cylinder head, a cup inner bottom surface and a bottomed hole of the inner member, And a coil spring as a lost motion spring installed in a compressed state.
[0019]
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.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
A variable valve mechanism according to a first embodiment of the present invention will be described below with reference to FIGS.
As shown in FIGS. 1 and 2, a swing arm type rocker arm 1 is used for the variable valve mechanism, and one end of the rocker arm 1 is supported by a pivot 3 with a concave spherical surface portion 2 formed in the same portion. It becomes the rocking center part. 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.
[0021]
A seesaw arm arrangement hole 6 formed in the cam corresponding part of the center of the rocker arm 1 is provided with a center part of a seesaw arm 7 formed in a substantially V shape, and the seesaw arm 7 swings around an axis perpendicular to the arm side wall. It is pivotally mounted. Therefore, the rocker arm 1 and the seesaw arm 7 swing in the same plane.
[0022]
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.
[0023]
One end side of the seesaw arm 7 extends to the valve pressing portion 4 side in the case of the rocker arm 1, and a first roller 9 as a first sliding contact portion is disposed in a fork formed at one end portion of the seesaw arm 7. Is pivotally mounted about an axis perpendicular to the fork sidewall. The other end side of the seesaw arm 7 extends to the swinging central portion side in the case of the rocker arm 1, and a second roller 10 as a second sliding contact portion is disposed in the fork formed at the other end portion. 10 is rotatably mounted around an axis perpendicular to the fork side wall.
[0024]
Above the first roller 9, a single camshaft 22, which forms a first rotating cam 20 that presses the first roller 9 and a second rotating cam 21 positioned adjacent to the first rotating cam 20, It arrange | positions so that it may extend at a right angle direction, and is rotatably supported by the shaft support member which is not shown in figure.
[0025]
The first rotating cam 20 includes a base circle 20a, a nose gradually increasing portion 20b in which the protruding amount gradually increases, a nose 20c having the maximum protruding amount, and a nose gradually decreasing portion 20d in which the protruding amount gradually decreases.
[0026]
The second rotating cam 21 includes a base circle 21a, a nose gradually increasing portion 21b in which the protruding amount gradually increases, a nose 21c having the maximum protruding amount, and a nose gradually decreasing portion 21d in which the protruding amount gradually decreases, and the protrusion of the nose 21c. The amount is smaller than that of the nose 20c.
[0027]
Above the second roller 10, a single cylindrical support shaft 30 is disposed in parallel with the camshaft 22, and is supported by a shaft support member (not shown) so as not to rotate. On the outer periphery of the support shaft 30, a control cam 36 and an intervening arm 37, which are intervening members acting on the second roller 10 in association with the second rotating cam 21, are arranged so as to press the second roller 10. A control cam 36 and a substantially cup-shaped intervening arm 37 located adjacent to the control cam 36 are pivotally mounted so as to be rotatable at a small angle and not to move in the longitudinal direction of the support shaft 30. Further, the intervening arm 37 is urged in the left rotation direction in FIG. The intervening arm 37 and the control cam 36 can change relative angles by fitting the cup open ends to the inner and outer peripheries (in the illustrated example, the control cam 36 is on the inner peripheral side) so as to be relatively rotatable. Furthermore, it couple | bonds via the slider 34 mentioned later.
[0028]
The outer peripheral surface of the control cam 36 includes a cylindrical surface portion 36 a and a protruding portion 36 b that extends tangentially from the cylindrical surface portion 36 a and presses the second roller 10. The lower surface of the projecting portion 36b is formed with a concave curved surface smoothly connected to the cylindrical surface portion 36a, and is a concave surface portion 36c having a radius of curvature larger than the radius of the second roller 10, and is curved in a direction away from the support shaft 30. .
[0029]
A pair of roller support portions 40 extending toward the second rotary cam 21 are provided on the outer peripheral surface of the intervening arm 37 so as to project. An intervening roller 41 as an intervening sliding contact portion pressed by the second rotary cam 21 is disposed in the roller support portion 40, and the intervening roller 41 is rotatable around an axis orthogonal to the side wall of the roller support portion 40. It is attached to the shaft. Therefore, when the second rotating cam 21 rotates, the intervening roller 41 receives pressure, and the intervening arm 37 and the control cam 36 rotate at a small angle. At this time, the second roller 10 moves the contact position with respect to the control cam 36 to the cylindrical surface portion 36a. Is smoothly pressed to the concave surface portion 36c while being pressed downward, and the pressing amount of the second roller 10 by the control cam 36 increases as the contact position moves to the tip of the concave surface portion 36c. It is like that.
[0030]
Further, in the present embodiment, the first rotating cam 20 and the second rotating cam 21 are configured such that the nose gradually increasing portion 21b, the nose 21c, and the nose gradually decreasing portion 21d of the second rotating cam 21 rather than the nose gradually increasing portion 20b of the first rotating cam 20. Is formed to precede. Further, since the control cam 36 is formed with a protruding portion 36b (and a concave portion 36c on the lower surface thereof) to press the second roller 10, the seesaw arm is pressed when the first rotating cam 20 presses the first roller 9. The rocker arm 1 is swung by displacing 7 while swinging. Accordingly, the main lift of the valve 5 is generated, but before the first rotating cam 20 starts to press the first roller 9, the second rotating cam 21 presses the interposing roller 41 and the interposing arm 37. And the control cam 36 are rotated by a small angle. At this time, the second roller 10 is pressed by the control cam protrusion 36b (a concave surface portion 36c formed on the lower surface thereof) that rotates by a small angle, and the seesaw arm 7 swings. However, since it is displaced downward, a sub lift with a smaller lift amount than the main lift is generated. That is, in the present embodiment, the first rotary cam 20 and the second rotary cam 21 are set so that the timing at which the second rotary cam 21 sub-lifts the valve 5 comes before the timing at which the first rotary cam 20 causes the valve to main lift. An interposition member (the control cam 36) is formed.
[0031]
As shown in FIG. 3, a substantially cylindrical slider 34 is inserted into the cup of the intervening arm 37 and the control cam 36 on the outer periphery of the support shaft 30 so as to be rotatable by a small angle in the length direction of the support shaft 30. ing. Corresponding to the inner diameter of the interposed arm 37 being larger than the inner diameter of the control cam 36, the outer diameter of the portion corresponding to the interposed arm 37 of the slider 34 is larger than the outer diameter of the portion corresponding to the control cam 36. .
[0032]
An annular groove 35 is formed on the inner peripheral surface of the slider 34, and a connect pin 33 described below is engaged with the annular groove 35. That is, a cylindrical control shaft 32 is slidably inserted into the support shaft 30, and a connection pin 33 protruding in the radial direction is screwed to one portion of the control shaft 32. In order to allow displacement of the connect pin 33 due to the sliding of the control shaft 32, a long hole 31 extending in the length direction and passing through the connect pin 33 is provided at one portion of the support shaft 30. The tip of the connect pin 33 inserted through the long hole 31 engages with the annular groove 35, so that the slider 34 can slide in the length direction together with the control shaft 32, and the control shaft in the rotation direction. It is possible to rotate independently of 32. This rotation allows a small angle rotation of the intervening arm 37 and the control cam 36.
[0033]
Straight splines 38 and 39 that are engaged with each other are cut at a portion corresponding to the interposition arm 37 on the outer peripheral surface of the slider 34 and an inner peripheral surface of the interposition arm 37. Helical splines 43 and 44 that engage with each other are cut at a portion corresponding to the control cam 36 on the outer peripheral surface of the slider 34 and an inner peripheral surface of the control cam 36. In order to simplify the illustration, the helical splines 43 and 44 are also depicted as straight in FIG. 3, but are actually helical. As described above, the slider 34 is engaged with both the intervening arm 37 and the control cam 36 via the spline, so that the intervening arm 37 and the control cam 36 are coupled so that the relative angle can be changed as described above.
[0034]
The control shaft 32 is moved in the length direction by a hydraulic mechanism (not shown). These hydraulic mechanisms, the control shaft 32, the connect pin 33, the slider 34, and the helical splines 43 and 44 make the relative angle of the control cam 36 with respect to the intervening arm 37 continuous or stepwise (preferably The relative angle control device is configured to change the lift amount and the working angle of the valve 5 in three stages or more, more preferably four stages or more. That is, when the control shaft 32 moves in the length direction, the slider 34 moves through the connecting pin 33. At this time, the intervening arm 37 does not rotate by the straight splines 38 and 39, but by the helical splines 43 and 44. Since the control cam 36 rotates by a small angle, the relative angle of the control cam 36 with respect to the intervening arm 37 can be shifted. The relative angle change is controlled by a control device such as a microcomputer based on a detected value from a rotation sensor or an accelerator opening sensor of the internal combustion engine.
[0035]
With the above configuration, the camshaft 22 rotates and the first rotating cam 20 presses the first roller 9. When the second rotating cam 21 presses the intervening roller 41, the control cam 36 and the intervening arm 37 are moved. Two inputs, that is, an input that the control cam 36 presses the second roller 10 by rotating by a small angle presses the seesaw arm 7 and the rocker arm 1 swings. Since the intervening arm 37 is urged counterclockwise by a member (not shown), the intervening roller 41 is always brought into sliding contact with the second rotating cam 21. Therefore, when the intervening roller 41 is in sliding contact with the base circle 21a of the second rotating cam 21, the intervening arm 37 is stagnant at the small angle rotation start position. However, when the intervening roller 41 starts to slidably contact the nose gradually increasing portion 21b, the intervening arm 37 starts to rotate at a small angle in the clockwise direction, and the contact position of the intervening roller 41 with the second rotating cam 21 reaches the nose 21c. The intervening arm 37 stops the small angle rotation and reaches the small angle rotation end position. Thereafter, when the intervening roller 41 starts to slidably contact the nose gradually decreasing portion 21d, the intervening arm 37 starts rotating at a small angle by changing the rotation direction to the left, and when the intervening roller 41 comes into slidable contact with the base circle 21a. 37 returns to the small angle rotation start position and stops. That is, the intervening arm 37 repeats reciprocating small angle rotation from the small angle rotation starting position to the small angle rotating end position by the input of the second rotating cam 21, and the control cam 36 also repeats reciprocating small angle rotation together with the intervening arm 37. Become. When the second roller 10 is pressed downward by the concave surface portion 36c of the control cam 36 during the reciprocating small-angle rotation, the seesaw arm 7 is also displaced according to the amount and the rocker arm 1 is swung. Accordingly, the valve 5 is sublifted. Further, when the first rotating cam 20 makes the maximum pressure on the first roller 9, a main lift that can obtain a larger lift amount than the sub-lift of the valve 5 by the reciprocating small-angle rotation of the control cam 36 described above. Is supposed to occur.
[0036]
When the relative angle of the control cam 36 with respect to the intervening arm 37 is shifted by the relative angle control device, the small angle rotation amount of the intervening arm 37 and the control cam 36 does not change, but the small angle rotation start position and the small angle rotation end of the control cam 36 are not changed. Since the position is also shifted by an amount shifted by the relative angle, the concave surface portion 36c formed in the control cam 36 is similarly shifted in the small angle rotation start position and the small angle rotation end position. Due to this action, the pressing amount and the working angle by the concave surface portion 36c of the second roller 10 are changed, so that the sub-lift amount of the valve 5 and the working angle of the sub-lift can be changed. Further, when the main lift of the valve 5 occurs, the first roller 9 is pressed downward by the first rotating cam 20, so that the second roller 10 disposed at the other end of the seesaw arm 7 is counteracted. Receives an upward force. At this time, if the relative angle of the control cam 36 is shifted with respect to the intervening arm 37 so as to reduce the sub-lift amount, the second roller 10 continues to be in sliding contact with the cylindrical surface portion 36a. 36 c is not involved, and the valve 5 is lifted according to the amount of pressing of the first roller 9. However, if the relative angle between the intervening arm 37 and the control cam 36 is shifted so as to increase the sub-lift amount, the second roller 10 is pressed by the concave surface portion 36c according to the shifted amount, and the second roller 10 moves upward in the upward direction. Since 10 is restricted from escaping, the concave surface portion 36c acts to increase the lift amount and operating angle of the valve 5. That is, although only one camshaft 22 is rotated, the main lift amount, sublift amount, and sublift operating angle of the valve 5 can be continuously changed.
[0037]
The variable valve mechanism configured as described above operates as follows.
First, FIGS. 4 (a) → (b) → FIG. 5 (a) → (b) show the relative angles of the intervening arm 37 and the control cam 36 under the operation condition requiring the maximum sub-lift and the operation due to the relative angles. .
As shown in FIG. 4A, when the base circle 20a of the first rotating cam 20 is in sliding contact with the first roller 9 and the base circle 21a of the second rotating cam 21 is in sliding contact with the interposed roller 41, the interposed arm 37 and the control cam 36 stay at the small angle rotation start position, and the first roller 9 is at the uppermost position. Since the relative angle of the intervening arm 37 and the control cam 36 is controlled so as to realize the maximum sub-lift, the small angle rotation start position of the concave surface portion 36c is controlled to the lowest position. The boundary between the cylindrical surface portion 36a and the concave surface portion 36c of 36 is in sliding contact. In this state, when the control cam 36 starts to rotate at a small angle in the clockwise direction, the second roller 10 is simultaneously pushed down by the concave surface portion 36c and the valve 5 starts to lift. At this time, since the second roller 10 is at the uppermost position as well as the first roller 9, the seesaw arm 7 is at the uppermost position and the rocker arm 1 is also stagnated at the uppermost position, so the lift amount of the valve 5 becomes zero.
As shown in FIG. 4 (b), when the first roller 9 continues to be in sliding contact with the base circle 20a and the intervening roller 41 is pressed against the nose 21c through the nose gradually increasing portion 21b, the intervening roller 41 is rotated in the second rotation. When the cam 21 receives the maximum pressure, the intervening arm 37 and the control cam 36 rotate by a small angle in the clockwise direction to reach the small angle rotation end position. At this time, since the concave surface portion 36c is rotated by a small angle, the contact position of the second roller 10 with respect to the control cam 36 is shifted from the cylindrical surface portion 36a to the concave surface portion 36c, and the second roller 10 is pressed downward by the concave surface portion 36c. In response, the seesaw arm 7 is depressed. Accordingly, the rocker arm 1 is also swung, and the lift amount L of the valve 5 is generated and increased to reach the maximum sub lift amount Lsmax.
As shown in FIG. 5 (a), when the intervening roller 41 comes into sliding contact with the base circle 21a via the nose gradually decreasing portion 21d, the amount of pressing by the second rotating cam 21 received by the intervening roller 41 decreases, and the intervening arm 37 and the control cam 36 rotate by a small angle in the counterclockwise rotation direction and return to the small angle rotation start position. At this time, the first roller 9 comes into sliding contact with the base circle 20a, and the contact position of the second roller 10 with respect to the control cam 36 returns to the boundary between the cylindrical surface portion 36a and the concave surface portion 36c, so that the seesaw arm 7 and the rocker arm 1 are shown in FIG. ) And the lift amount of the valve 5 decreases and becomes zero. Further, as described above, the sub-lift of the valve 5 when controlled to achieve the maximum sub-lift is when the contact position of the intervening roller 41 with respect to the second rotating cam 21 is switched from the base circle 21a to the nose gradually increasing portion 21b. From the nose gradually decreasing portion 21d to the base circle 21a, the operating angle is maximized.
As shown in FIG. 5 (b), when the first roller 9 comes into sliding contact with the nose 20c via the nose gradually increasing portion 20b, the intervening roller 41 is in sliding contact with the base circle 21a, so that the concave surface portion 36c rotates by a small angle. The first roller 9 reaches the maximum pressing position, and the second roller 10 disposed at the other end of the seesaw arm 7 receives an upward force as a reaction. However, since the relative angle between the control cam 36 and the intervening arm 37 is controlled so as to realize the maximum sub-lift, the second roller 10 moves the contact position with respect to the control cam 36 toward the tip of the concave portion 36c, You are restricted from escaping upwards. Accordingly, at this time, the pressing amount of the seesaw arm 7 by the first roller 9 is increased by the concave surface portion 36c restricting the rising of the second roller 10, so that the lift amount L of the valve 5 is again generated and increased, The main lift amount Lmmax is reached.
[0038]
Next, FIGS. 6 (a) → (b) → FIG. 7 (a) → (b) show the relative angles of the intervening arm 37 and the control cam 36 under the operating condition that requires a minute sub-lift, and the action due thereto. Yes.
As shown in FIG. 6A, when the base circle 20a is in sliding contact with the first roller 9 and the base circle 21a is in sliding contact with the intervening roller 41, the interposing arm 37 and the control cam 36 are at the small angle rotation start position. The first roller 9 is at the uppermost position. Since the relative angle of the intervening arm 37 and the control cam 36 is controlled so as to realize a minute sublift, the small angle rotation start position of the concave surface portion 36c is shifted upward as compared with FIG. The cylindrical surface portion 36a comes into sliding contact with the roller 10, and the second roller 10 and the concave surface portion 36c begin to separate. In this state, even if the control cam 36 starts to rotate at a small angle in the clockwise direction, the valve 5 does not lift while the second roller 10 is in sliding contact with the cylindrical surface portion 36a. That is, the working angle of the sublift is reduced in accordance with the distance between the second roller 10 and the concave surface portion 36c. At this time, the lift amount of the valve 5 becomes zero because the second roller 10 is at the uppermost position as well as the first roller 9.
As shown in FIG. 6B, when the first roller 9 comes into sliding contact with the base circle 20a and the intervening roller 41 is pressed against the nose 21c, the intervening roller 41 receives the maximum pressure by the second rotating cam 21. The intervening arm 37 and the control cam 36 rotate by a small angle to the small angle rotation end position. At this time, the contact position of the second roller 10 with respect to the control cam 36 shifts from the cylindrical surface portion 36a to the concave surface portion 36c, but the small-angle rotation start position of the concave surface portion 36c is shifted in the left rotation direction compared to the maximum sub-lift. The amount of transition to the concave surface portion 36c is reduced accordingly. Accordingly, the second roller 10 is slightly pressed downward by the concave surface portion 36c that has been rotated by a small angle to slightly press the seesaw arm 7. Along with this, the rocker arm 1 also slightly swings, and the lift amount L of the valve 5 is generated and increased to reach the sub lift amount Ls.
As shown in FIG. 7A, when the intervening roller 41 comes into sliding contact with the base circle 21a, the amount of pressing by the second rotating cam 21 received by the intervening roller 41 decreases, and the intervening arm 37 and the control cam 36 are A small angle is rotated in the left rotation direction to return to the small angle rotation start position. At this time, the first roller 9 is in sliding contact with the base circle 20a, and the contact position of the second roller 10 with respect to the control cam 36 returns to the cylindrical surface portion 36a, so that the seesaw arm 7 and the rocker arm 1 return to the same positions as in FIG. The lift amount of the valve 5 decreases to zero.
As shown in FIG. 7B, when the first roller 9 comes into sliding contact with the nose 20c, the interposed roller 41 continues to slide into the base circle 21a, so that the concave surface portion 36c stays at the small angle rotation start position. The first roller 9 reaches the maximum pressing position, and the second roller 10 disposed at the other end of the seesaw arm 7 receives the upward force as a reaction. However, since the relative angle between the control cam 36 and the intervening arm 37 is controlled so as to realize a minute sublift, the second roller 10 moves the contact position with respect to the control cam 36 closer to the proximal end portion of the concave surface portion 36c. It is limited to a certain extent, and it is somewhat restricted from escaping upward. Accordingly, at this time, the pressing amount of the seesaw arm 7 by the first roller 9 is slightly increased by the concave surface portion 36c slightly restricting the rise of the second roller 10, so that the lift amount L of the valve 5 is generated and increased again. The main lift amount Lm1 is reached.
[0039]
Note that, in an operating situation where an intermediate lift amount / working angle between FIGS. 4 and 5 and FIGS. 6 and 7 is required, an intermediate arm 37 intermediate between FIGS. 4 and 5 and FIGS. Further, the relative angle of the control cam 36 is created continuously or stepwise by the relative angle control device, and an intermediate lift amount / working angle is obtained continuously or stepwise as shown in FIG.
[0040]
Next, FIGS. 8 (a) → (b) → FIG. 9 (a) → (b) show the relative angles of the intervening arm 37 and the control cam 36 under the operating condition where the sub-lift stop is necessary, and the action due thereto. Yes.
As shown in FIG. 8A, when the base circle 20a is in sliding contact with the first roller 9 and the base circle 21a is in sliding contact with the intervening roller 41, the interposing arm 37 and the control cam 36 are at the small angle rotation start position. The first roller 9 is at the uppermost position. Since the relative angle of the intervening arm 37 and the control cam 36 is controlled so as to realize the sublift stop, the small angle rotation start position of the concave surface portion 36c is further shifted upward as compared with FIG. The cylindrical surface portion 36a is in sliding contact with the two rollers 10, and the distance between the second roller 10 and the concave surface portion 36c is maximized. At this time, the lift amount of the valve 5 becomes zero because the second roller 10 is at the uppermost position as well as the first roller 9.
As shown in FIG. 8B, when the first roller 9 comes into sliding contact with the base circle 20a and the intervening roller 41 is pressed against the nose 21c, the intervening roller 41 receives the maximum pressure by the second rotating cam 21. The intervening arm 37 and the control cam 36 rotate by a small angle to the small angle rotation end position. However, since the small angle rotation start position of the concave surface portion 36c is further shifted in the left rotation direction than that during the minute sub-lift, the contact position of the second roller 10 with respect to the control cam 36 approaches the concave surface portion 36c from the cylindrical surface portion 36a. The concave surface portion 36c is not reached but remains on the cylindrical surface portion 36a. Therefore, since the second roller 10 and the first roller 9 do not move from the uppermost position, the sub-lift amount L of the valve 5 is 0, and the working angle of the sub-lift is also 0.
As shown in FIG. 9A, when the intervening roller 41 comes into sliding contact with the base circle 21a, the amount of pressing by the second rotating cam 21 received by the intervening roller 41 decreases, and the intervening arm 37 and the control cam 36 are A small angle is rotated in the left rotation direction to return to the small angle rotation start position. At this time, the first roller 9 is in sliding contact with the base circle 20a, and the contact position of the second roller 10 with respect to the control cam 36 does not change from the cylindrical surface portion 36a, so that the seesaw arm 7 and the rocker arm 1 are not displaced, and the lift amount of the valve 5 Maintains 0.
As shown in FIG. 9B, when the first roller 9 comes into sliding contact with the nose 20c, the intervening roller 41 is in sliding contact with the base circle 21a, so that the concave portion 36c continues to stay at the small angle rotation start position. However, the first roller 9 reaches the maximum pressing position, and as a reaction, the second roller 10 disposed on the other end of the seesaw arm 7 receives an upward force. However, since the relative angle between the control cam 36 and the intervening arm 37 is controlled so as to realize the sublift pause, the second roller 10 moves the contact position with respect to the control cam 36 from the cylindrical surface portion 36a to the concave surface portion 36c. Although it moves, it does not reach the concave surface portion 36c but remains on the cylindrical surface portion 36a. Accordingly, at this time, the second roller 10 is not restricted by the concave portion 36c, so that the pressing amount of the second roller 10 becomes smaller than that in FIG. 7B, and the lift amount L of the valve 5 is generated and increased. The main lift amount Lm2 smaller than Lm1 is reached.
[0041]
Next, only a different part from 1st embodiment is demonstrated with reference to FIGS. 11-20 about 2nd Embodiment of the variable valve mechanism which implemented this invention. FIG. 11 uses a control cam 36 having a concave surface in the variable valve mechanism of the first embodiment.
[0042]
The outer peripheral surface of the control cam 36 of the present embodiment has a cylindrical surface portion 36a and a concave surface portion 36e formed in a part thereof, and a part of the boundary between the cylindrical surface portion 36a and the concave surface portion 36e is a boundary portion 36d having a smooth curved surface. It has become. When the control cam 36 rotates by a small angle, the contact position of the control cam 36 with respect to the second roller 10 can smoothly move from the cylindrical surface portion 36a through the boundary portion 36d to the concave surface portion 36e, and also in the reverse direction. It can be done. The cylindrical surface portion 36a acts to press the second roller 10, but the concave surface portion 36e rather acts to allow the second roller 10 to enter and escape, so that the lift amount of the valve 5 is reduced.
[0043]
The first rotating cam 23 is formed with a base circle 23a, a sub nose 24, and a main nose 25 following the sub nose 24. The sub nose 24 includes a nose gradually increasing portion 24b, a nose 24c, and a nose gradually decreasing portion 24d. It consists of a nose gradually increasing portion 25b, a nose 25c, and a nose gradually decreasing portion 25d.
[0044]
The second rotating cam 26 has a larger protruding amount in order to increase the small angle rotation amount of the control cam 36 than in the first embodiment, and a nose gradually increasing portion 26b in which the protruding amount gradually increases, a nose 26c, and a protruding amount Consists of a nose gradually decreasing portion 26d.
[0045]
A relief groove for preventing the interference of the second rotary cam 26 on the upper surface of the intervening arm 37 so that the nose does not interfere with the intervening arm 37 as the amount of protrusion of the nose of the second rotary cam 26 increases. 42 is formed. Accordingly, since both the intervening arm 37 and the control cam 36 are formed with the relief groove 42 and the concave surface portion 36e so as not to affect the internal relative angle control device, as shown in FIG. The direction is long.
[0046]
According to the above configuration, in the first embodiment, the second roller 10 is pressed against the concave surface portion 36c formed on the projecting portion 36b of the control cam 36 and acts to increase the lift amount of the valve 5. In the embodiment, the concave surface portion 36e provided in the control cam 36 acts to allow the second roller 10 to enter and escape, thereby acting in a direction to reduce the lift amount of the valve 5. Therefore, in the present embodiment, the lift amount of the valve 5 is increased or decreased by the lift amount increasing action of the valve 5 by the first rotating cam 23 and the lift amount decreasing action of the valve 5 by the second rotating cam 26. Further, the sub-lift and the main lift of the valve 5 are configured such that the sub-nose 24 of the first rotating cam 23 generates a sub-lift and the main nose 25 generates a main lift.
[0047]
When the control cam 36 receives relative angle control with respect to the intervening arm 37 by the relative angle control device, the small angle rotation start position of the concave surface portion 36c projecting from the control cam 36 is changed in the first embodiment. In the embodiment, the small angle rotation start position of the concave surface portion 36e is changed so that the pressing amount of the second roller 10 can be changed.
[0048]
The variable valve mechanism configured as described above operates as follows.
First, FIG. 13 (a) → (b) → FIG. 14 (a) → (b) → FIG. 15 (a) → (b) → shows the intervening arm 37 and the control cam 36 under the driving condition requiring the maximum lift. The relative angle of and the action by it.
As shown in FIG. 13 (a), when the base circle 26a of the second rotating cam 26 is in sliding contact with the intervening roller 41, the control cam 36 is stagnant at the small angle rotation start position and realizes the maximum sublift. Thus, since the relative angle between the intervening arm 37 and the control cam 36 is controlled, the small angle rotation start position of the concave surface portion 36e is controlled to the highest position, and the cylindrical surface portion 36a of the second roller 10 is slidably contacted to the maximum. In the pressed position. However, since the first roller 9 is in the uppermost position in sliding contact with the base circle 23a, the lift amount of the valve 5 becomes zero.
As shown in FIG. 13B, the intervening roller 41 is in sliding contact with the base circle 26a. However, when the first roller 9 is pressed by the nose 24c via the nose gradually increasing portion 24b, the second roller 10 is The first roller 9 is pushed down by the nose 24c and pushes down the rocker arm 1 although it is not displaced while keeping sliding contact with the cylindrical surface portion 36a. At this time, the lift amount L of the valve 5 is generated and increased and reaches the maximum sub-lift amount Lsmax.
As shown in FIG. 14A, the intervening roller 41 is in sliding contact with the base circle 26a, but the first roller 9 is in sliding contact with the base circle 23a between the nose gradually decreasing portion 24d and the nose gradually increasing portion 25b. As a result, the first roller 9 returns to the uppermost position, and accordingly, the rocker arm 1 also returns to the uppermost position, so that the lift amount L of the valve 5 decreases to zero. Therefore, the valve 5 when controlled to achieve the maximum sub-lift is sub-lifted from the time when the first roller 9 starts to slidably contact the nose gradually increasing portion 24b to when the first roller 9 starts to slidably contact the base circle 23a. The working angle of the sublift is also maximized.
As shown in FIG. 14B, when the first roller 9 is pressed at the rear half of the nose gradually increasing portion 25b or the front half of the nose 25c, the first roller 9 starts to be pressed again. At that time, the intervening roller 41 is pressed by the nose gradually increasing portion 26b, and the intervening arm 37 and the control cam 36 start to rotate at a small angle in the clockwise direction, and the boundary portion 36d comes into sliding contact with the second roller 10. The second roller 10 starts to rise. At this time, the lift amount L of the valve 5 is generated and increased and reaches the maximum lift amount Lmax.
As shown in FIG. 15 (a), when the first roller 9 is pressed by the latter half of the nose 25c, the intervening roller 41 receives maximum pressing by the nose 26c, and the intervening arm 37 and the control cam 36 are Rotate a small angle to the small angle rotation end position and stop. At that time, since the control cam 36 works to allow the second roller 10 to enter the concave surface portion 36e to escape, the second roller 10 rises greatly despite the first roller 9 reaching the maximum pressing position. The lift amount L of the valve 5 decreases and becomes zero.
As shown in FIG. 15 (b), when the first roller 9 comes into sliding contact with the base circle 23a and the intervening roller 41 comes into sliding contact with the base circle 26a via the nose gradually decreasing portion 26d, the first roller 9 comes to the uppermost position. The intervening arm 37 and the control cam 36 return to the small angle rotation start position. As the control cam 36 rotates at a small angle at this time, the second roller 10 shifts the contact position with respect to the control cam 36 from the concave surface portion 36e to the cylindrical surface portion 36a via the boundary portion 36d. At this time, the second roller 10 is in sliding contact with the cylindrical surface portion 36a and reaches the maximum pressing position. However, the first roller 9 starts to be in sliding contact with the nose gradually decreasing portion 25d first, so the lift amount L of the valve 5 is maintained at zero.
Next, FIGS. 16 (a) → (b) → FIG. 17 (a) → (b) show the relative angles of the intervening arm 37 and the control cam 36 under the operation condition that requires a minute sub-lift amount, and the action due thereto. ing.
As shown in FIG. 16A, when the base circle 26a is in sliding contact with the intervening roller 41, the control cam 36 is stagnant at the small angle rotation start position, and the intervening arm 37 and the intervening arm 37 are realized so as to realize a minute sublift. Since the relative angle with the control cam 36 is controlled, the small angle rotation start position of the boundary portion 36d and the concave surface portion 36e is controlled near the lowest position, and the second roller 10 approaches the boundary portion 36d (described later). In the third embodiment). However, since the first roller 9 is in the uppermost position in sliding contact with the base circle 23a, the lift amount L of the valve 5 becomes zero.
As shown in FIG. 16B, the intervening roller 41 is in sliding contact with the base circle 26a. However, when the first roller 9 is pressed by the nose 24c via the nose gradually increasing portion 24b, the second roller 10 Ascending and coming into contact with the boundary portion 36d, the seesaw arm 7 is slightly pressed. At this time, since the rocker arm 1 is also subjected to minute swing, the lift amount L of the valve 5 is generated and increased to reach the sub lift amount Ls.
As shown in FIG. 17A, the intervening roller 41 is in sliding contact with the base circle 26a, but the first roller 9 is in sliding contact with the base circle 23a between the nose gradually decreasing portion 24d and the nose gradually increasing portion 25b. As a result, the first roller 9 returns to the uppermost position, and accordingly, the rocker arm 1 also returns to the uppermost position, so that the lift amount L of the valve 5 decreases to zero. Therefore, when the valve 5 is controlled so as to realize the minute sub-lift, even if the first roller 9 starts to slidably contact the nose gradually increasing portion 24b, the valve 5 does not lift immediately, and the second roller 10 contacts the control cam 36. Since the lift is started after the contact and the second roller 10 is lifted until the second roller 10 starts to move away from the control cam 36, the working angle of the sub-lift becomes very small.
As shown in FIG. 17B, when the first roller 9 is pressed by the nose gradually increasing portion 25b, the first roller 9 starts to be pressed again. At that time, the intervening roller 41 is pressed by the nose gradually increasing portion 26b, and the intervening arm 37 and the control cam 36 start to rotate at a small angle in the right rotation direction. As a result, the control cam 36 acts to cause the second roller 10 to enter the boundary portion 36d or the concave surface portion 36e to escape, and thus starts to act in the direction of reducing the lift amount of the valve 5. At this time, the lift amount L of the valve 5 is generated and increased and reaches the main lift amount Lm.
[0049]
It should be noted that in an operating situation where an intermediate lift amount / working angle between FIGS. 13, 14 and 15 and FIGS. 16 and 17 is required, the relationship between FIGS. 13, 14, and 15 and FIGS. The relative angle between the intermediate intervening arm 37 and the control cam 36 is created continuously or stepwise by the relative angle control device, and the intermediate lift amount / working angle is continuously or stepwise as shown in FIG. Is obtained.
Next, FIGS. 18 (a) → (b) → FIG. 19 (a) → (b) show the relative angles of the intervening arm 37 and the control cam 36 under the operation condition that requires the sublift stop, and the operation due to the relative angles. Yes.
As shown in FIG. 18 (a), when the base circle 26a is in sliding contact with the intervening roller 41, the control cam 36 is stagnant at the small angle rotation start position, and the intervening arm 37 and the intervening arm 37 so as to realize a minute sublift. Since the relative angle to the control cam 36 is controlled, the small-angle rotation start position of the boundary portion 36d and the concave surface portion 36e is controlled to the lowest position, and the concave surface portion 36e is oriented on the second roller 10 (described later). In the third embodiment). However, since the first roller 9 is in the uppermost position in sliding contact with the base circle 23a, the lift amount L of the valve 5 becomes zero.
As shown in FIG. 18B, the intervening roller 41 is in sliding contact with the base circle 26a, but when the first roller 9 is pressed by the nose 24c via the nose gradually increasing portion 24b, the seesaw arm 7 swings. Then, the second roller 10 tends to be displaced upward. However, the concave surface portion 36e is oriented on the second roller 10, and the control cam 36 works to allow the second roller 10 to enter the concave surface portion 36e to escape, so that the seesaw arm 7 swings. At this time, the pressing of the first roller 9 by the nose 24c swings the seesaw arm 7, but the swinging amount is not so large that the second roller 10 comes into contact with the concave surface part 36e. At this time, since the rocker arm 1 is not displaced, the valve 5 is in a sub-lift stop.
As shown in FIG. 19A, the intervening roller 41 is in sliding contact with the base circle 26a, but the first roller 9 is in sliding contact with the base circle 23a between the nose gradually decreasing portion 24d and the nose gradually increasing portion 25b. As a result, the first roller 9 returns to the uppermost position, and accordingly, the rocker arm 1 also returns to the uppermost position, so that the lift amount L of the valve 5 decreases to zero. Accordingly, at this time, the valve 5 does not generate a sub-lift, so the working angle of the sub-lift is zero.
As shown in FIG. 19B, when the first roller 9 is pressed by the nose gradually increasing portion 25b or the nose 25c, the first roller 9 starts to be pressed again. However, the concave surface portion 36e at the small angle rotation start position is already oriented to the second roller 10, and the nose gradually increasing portion 26b presses the intervening roller 41 to start rotating the concave surface portion 36e in the clockwise direction by a small angle. The control cam 36 advances the second roller 10 deeply into the concave surface portion 36e. Accordingly, the first rotating cam 23 pushes down the first roller 9, but the second roller 10 enters the concave surface portion 36e rotating at a small angle, and the seesaw arm 7 is sufficiently swung. Without displacement in the direction, the main lift amount L of the valve 5 becomes 0, and the main lift is also stopped.
[0050]
Next, the third embodiment of the variable valve mechanism embodying the present invention will be described with reference to FIG. FIG. 21 is obtained by adding a mechanical adjuster 50 as an adjuster to the variable valve mechanism of the second embodiment.
[0051]
The mechanical adjuster 50 includes a cup-shaped inner member 51 whose side peripheral walls engage with each other so that the opening side faces each other and can be brought into contact with and separated from each other, a bottomed hole 53 formed in the cylinder head 52, and the inner member 51. The inner member comprises a coil spring as a lost motion spring 54 that is installed in a compressed state between the inner bottom surface of the cup and the inner bottom surface of the bottomed hole 53 and biases the inner member 51 from the bottomed hole 53 in the separating direction. 51 is guided and slid inside the bottomed hole 53 of the cylinder head 52.
[0052]
In the second embodiment, there is a case where a gap is formed between the roller and the cam as described above. However, in this embodiment, the addition of the mechanical adjuster 50 causes the lost motion spring 54 to have the inner member 51 and the bottomed portion as shown in FIG. Since the pivot 3 is lifted by separating the holes 53, it is possible to prevent gaps from being formed in the respective parts, and thus prevent the rocker arm 1 from falling.
[0053]
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 relative angle control device as appropriate.
(2) Use a rocker arm with a rocking center at the center.
(3) Change the shape of the control cam as appropriate.
(4) Change the second rotating cam to a sub nose and main nose.
[0054]
【The invention's effect】
Since the variable valve mechanism of the present invention is configured as described above, the main lift amount, sub-lift amount, and sub-lift operation of the valve can be performed by rotating one camshaft without greatly changing the conventional drive system. Since the angle can be changed continuously or stepwise, the internal EGR can be optimally controlled, and the excellent fuel efficiency can be obtained.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a variable valve mechanism according to an embodiment of the present invention.
FIG. 2 is a perspective view depicting the angle of FIG.
FIG. 3 is a cross-sectional view showing a main part of a relative angle control device in the mechanism.
FIG. 4 is a cross-sectional view showing the operation of the mechanism when the maximum lift amount and operating angle are required.
FIG. 5 is a cross-sectional view showing the operation following FIG. 3;
FIG. 6 is a cross-sectional view showing the operation of the mechanism when a minute lift amount and operating angle are required.
FIG. 7 is a cross-sectional view showing the operation following FIG.
FIG. 8 is a cross-sectional view showing the operation of the mechanism when lift suspension is necessary.
FIG. 9 is a cross-sectional view showing the operation following FIG.
FIG. 10 is a graph showing a lift amount and a working angle of a valve obtained by the same mechanism.
FIG. 11 is a perspective view showing a variable valve mechanism according to a second embodiment of the present invention.
FIG. 12 is a cross-sectional view showing a main part of a relative angle control device in the mechanism.
FIG. 13 is a cross-sectional view showing the operation of the mechanism when the maximum sublift amount and operating angle are required.
14 is a cross-sectional view showing the operation following FIG.
15 is a cross-sectional view showing the operation following FIG.
FIG. 16 is a cross-sectional view showing the operation of the same mechanism when a small sublift amount and operating angle are required.
FIG. 17 is a cross-sectional view showing the operation following FIG.
FIG. 18 is a cross-sectional view showing the operation of the mechanism when sublift suspension is required.
FIG. 19 is a cross-sectional view showing the operation following FIG.
FIG. 20 is a graph showing a lift amount and a working angle of a valve obtained by the same mechanism.
FIG. 21 is a cross-sectional view showing a variable valve mechanism according to a third embodiment of the present invention.
[Explanation of symbols]
1 Rocker arm
5 Valve
7 seesaw arm
9 First roller as first sliding contact
10 Second roller as second sliding contact
20 First rotating cam
21 Second rotating cam
22 Camshaft
24 Subnose
25 Main nose
30 Support shaft
32 Control shaft
33 Connect Pin
34 Slider
36 Control cam as intervening member
36b Projection
36e Concave surface
37 Intervening arm as intervening member
41 Intervening roller as intervening sliding contact portion

Claims (7)

A seesaw arm is pivotally attached to the cam corresponding part of the rocker arm so that it can swing at its center.
A first sliding contact portion and a second sliding contact portion are provided on one end and the other end of the seesaw arm, respectively.
A single camshaft that forms a first rotating cam that presses the first sliding contact portion above the first sliding contact portion and a second rotating cam that is positioned adjacent thereto is rotatably supported.
An interposition member acting on the second sliding contact portion in relation to the second rotating cam is provided above the second sliding contact portion so as to be displaceable.
At least one of the first rotating cam, the second rotating cam, and the interposed member is formed to generate a valve sub-lift and a main lift following the sub-lift,
By providing a relative angle control device that changes the amount of action of the second sliding contact portion by the interposition member continuously or stepwise according to the operating state of the internal combustion engine, the main lift amount and the sub lift amount of the valve are changed. Variable valve mechanism. The interposition member can change a relative angle between a control cam provided with a projecting portion that presses the second sliding contact portion of the seesaw arm and an interposition arm provided with the interposing sliding contact portion that is pressed by the second rotating cam. 2. The variable valve mechanism according to claim 1, wherein the variable valve mechanism is attached to a single support shaft so as to be rotatable at a small angle. A control cam having a concave surface that acts to allow the interposition member to enter and escape the second sliding contact portion of the seesaw arm; and an intervening arm having an intervening sliding contact portion pressed by the second rotating cam. 2. The variable valve mechanism according to claim 1, wherein the variable valve mechanism is coupled so as to be capable of changing a relative angle and is pivotally attached to a single support shaft so as to be rotatable at a small angle. The first rotating cam and the second rotating cam are interposed so that the second rotating cam lifts the valve via the interposition member at a timing different from the timing at which the first rotating cam presses the first sliding contact portion and lifts the valve. The variable valve mechanism according to claim 1 or 2, wherein a member is formed. The variable valve mechanism according to any one of claims 1 to 4, wherein at least one of the first rotating cam and the second rotating cam is formed with a sub nose and a main nose following the sub nose. The variable valve mechanism according to any one of claims 2 to 5, wherein the intervening sliding contact portion is a roller rotatably mounted on the intervening arm. The variable valve mechanism according to any one of claims 1 to 6, wherein at least one of the first sliding contact portion and the second sliding contact portion is a roller rotatably mounted on the seesaw arm. .

Images