JP4108293B2 - 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.
[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. .
[0004]
Accordingly, an object of the present invention is to solve the above-mentioned problems and rotate one camshaft to change the lift amount and working angle of the valve continuously or stepwise without greatly changing the conventional drive system. It is an object of the present invention to provide a variable valve mechanism that can perform the above operation.
[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. A contact portion and a second slidable contact portion are provided, and a single camshaft forming a first rotary cam that presses the first slidable contact portion and a second rotary cam positioned adjacent thereto is rotatably supported. Since the interposition member is displaceably provided above the second sliding contact portion, when the second rotating cam rotates and acts on the interposition member, the interposition member is displaced and acts on the second sliding contact portion. In addition, a relative angle control device for changing the lift amount and the working angle of the valve by changing the amount of action of the second sliding contact portion by the intervening member continuously or stepwise according to the operating condition of the internal combustion engine is provided. It is characterized by. 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 intervening 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 having an interposing sliding contact portion pressed by the second rotating cam, An example is one that is coupled so as to be capable of changing the relative angle and that is attached to one support shaft so as to be capable of rotating at a small angle.
[0007]
As the interposition member, a control cam having a concave surface that presses the second slidable contact portion of the seesaw arm and an intervening arm having an intervening slidable portion pressed by the second rotary cam are coupled so that the relative angle can be changed. The support shaft is pivotally attached to the support shaft so as to be rotatable at a small angle , and the concave surface can be exemplified by a protrusion formed on the control cam .
[0008]
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.
[0009]
The first sliding contact portion and the second sliding contact portion may be a fixed hard chip or a rotatable roller. However, considering the sliding resistance and wear between the sliding portion and the cam, at least one (preferably both) of the first sliding contact portion and the second sliding contact portion is a shaft on which the roller can rotate on the seesaw arm. Those worn are preferred.
[0010]
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.
[0011]
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.
[0012]
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.
[0013]
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.
[0014]
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.
[0015]
An adjuster that prevents a gap from being formed between each roller and the cam may be connected to the swing center portion. 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.
[0016]
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 in which a male screw provided on a pivot is screwed into a female screw provided on an adjuster so that the screwing amount can be adjusted can be exemplified.
[0017]
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.
[0018]
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.
[0019]
The seesaw arm disposition hole 6 formed in the cam corresponding part at the center of the rocker arm 1 is provided with the center part of the seesaw arm 7 formed in an upward warp, and the seesaw arm 7 swings around an axis orthogonal to the arm side wall. It is pivotally attached as possible. Therefore, the rocker arm 1 and the seesaw arm 7 swing in the same plane.
[0020]
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.
[0021]
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.
[0022]
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.
[0023]
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 that continues at a wide angle with substantially the same protruding amount, and a nose gradually decreasing portion 20d in which the protruding amount gradually decreases.
[0024]
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 that continues at a wide angle with substantially the same protruding amount, and a nose gradually decreasing portion 21d in which the protruding amount gradually decreases.
[0025]
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 are disposed as interposition members, and a substantially cup-shaped control cam 36 that presses the second roller 10 and a substantially cup-shaped interposition located next thereto. The arm 37 is pivotally attached so that it can rotate at a small angle and does not move in the longitudinal direction of the support shaft 30, and the intervening arm 37 is urged in the counterclockwise rotation direction in FIG. 1 by a member (not shown). 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.
[0026]
The outer peripheral surface of the control cam 36 has a cylindrical surface portion 36a and a concave surface portion 36c formed in a part thereof, and a part of the boundary between the cylindrical surface portion 36a and the concave surface portion 36c is a boundary portion 36b having a smooth curved surface. . 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 36b to the concave surface portion 36c, and also smoothly 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 36c rather acts to allow the second roller 10 to enter and escape, so that the lift amount of the valve 5 is reduced.
[0027]
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 and presses the intervening roller 41 which is the intervening sliding contact portion, the control cam 36 rotates by a small angle together with the intervening arm 37, and the contact position of the control cam 36 with respect to the second roller 10 changes. As a result, the pressing amount of the second roller 10 is changed. An escape groove 42 is formed on the upper surface of the intervening arm 37 to prevent the second rotating cam 21 from coming into contact and prevent interference.
[0028]
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 as shown in FIG. 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. .
[0029]
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.
[0030]
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. 2, 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.
[0031]
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.
[0032]
With the above configuration, when the first rotating cam 20 rotates and presses the first roller 9, and when the second rotating cam 21 rotates and presses the interposing roller 41, the control cam 36 together with the interposing arm 37 has a small angle. The seesaw arm 7 is pressed and the rocker arm 1 is swung by two inputs, that is, the input of rotating and pressing the second roller 10. 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 contact the nose gradually increasing portion 21b, the intervening arm 37 starts to rotate at a small angle in the clockwise direction, and the interposing arm 37 continues to rotate at a small angle as the contact position advances. Thereafter, when the contact position of the interposed roller 41 with respect to the control cam 36 shifts to the nose 21c, the small angle rotation of the intermediate arm 37 stops and the intermediate arm 37 stays at the small angle rotation end position. When the rotation of the second rotating cam 21 further advances and the contact position of the intervening roller 41 reaches the nose gradually decreasing portion 21d, the intervening arm 37 starts to rotate counterclockwise and the contact position of the intervening roller 41 returns to the base circle 21a. Sometimes the intervening arm 37 returns to the small angle rotation start position. That is, the interposition arm 37 repeats reciprocation from the small angle rotation start position to the small angle rotation end position, and the control cam 36 also repeats reciprocation together with the interposition arm 37.
[0033]
When the relative angle of the control cam 36 relative to the intervening arm 37 is shifted by the relative angle control device, the small angle rotation start position and the small angle rotation end position of the control cam 36 are also shifted in the same direction by the same angle. This changes the angle difference from the position of the control cam 36 at the small angle rotation start position to the position of the control cam 36 at which the second roller 10 starts to slidably contact the boundary portion 36b. The smaller this angle difference is, the shorter the time from when the intervening arm 37 starts to rotate at a small angle until the second roller 10 starts to slidably contact the boundary portion 36b. The second roller 10 has already started to slidably contact the position boundary 36b or the concave surface 36c. That is, by changing the relative angle of the control cam 36 with respect to the intervening arm 37, the contact position of the second roller 10 with respect to the control cam 36 is changed in parallel with the first rotating cam 20 pressing the first roller 9. Thus, the pressing amount and operating angle of the rocker arm 1 can be changed by changing the pressing amount of the second roller 10. That is, although only one camshaft 22 is rotated, the lift amount and operating angle of the valve 5 can be continuously changed.
[0034]
The variable valve mechanism configured as described above operates as follows.
First, FIG. 3 (a) → (b) → FIG. 4 (a) → (b) shows the relative angles of the intervening arm 37 and the control cam 36 under the driving conditions requiring the maximum lift amount and the maximum working angle, and the results. It shows the action.
As shown in FIG. 3A, when the first rotating cam 20 is in sliding contact with the first roller 9 at the boundary between the base circle 20a and the nose gradually increasing portion 20b, the intervening roller 41 has a base circle of the second rotating cam 21. The rear half of 21a is in sliding contact, and the intervening arm 37 and the control cam 36 are stagnant at the small angle rotation start position. At this time, the second roller 10 is pressed to the maximum pressing position by the cylindrical surface portion 36a of the control cam 36, but since the first roller 9 is at the uppermost position, the rocker arm 1 is also stagnated at the uppermost position and the lift amount of the valve 5 is increased. Becomes 0.
As shown in FIG. 3B, when the first half of the nose 20c presses the first roller 9, the first roller 9 reaches the maximum pressed position. The intervening roller 41 is pressed by the nose gradually increasing portion 21b, and the intervening arm 37 and the control cam 36 are rotated by a small angle in the clockwise direction. At this time, since the second roller 10 is in sliding contact with the boundary between the cylindrical surface portion 36a and the boundary portion 36b and the second roller 10 is also in the maximum pressed position, the lift amount L of the valve 5 is generated and increased to reach the maximum value Lmax. The working angle is also maximized.
As shown in FIG. 4A, when the first roller 9 is pressed by the rear half of the nose 20c, the pressing by the nose gradually increasing portion 21b of the intervening roller 41 further proceeds, and the interposing arm 37 and the control cam 36 are moved. The nose 21c comes into sliding contact with the intervening roller 41 by continuing the small angle rotation in the clockwise direction. At that time, the intervening roller 41 receives the maximum pressure from the nose 21c, and the intervening arm 37 and the control cam 36 are stagnated at the respective small angle rotation end positions. At this time, since the contact position of the second roller 10 with respect to the control cam 36 moves from the boundary portion 36b to the concave surface portion 36c, the control cam 36 works so as to allow the second roller 10 to enter the concave surface portion 36c and escape. Accordingly, the rocker arm 1 is also lifted by the rising of the second roller 10 even though the first roller 9 has reached the maximum pressing position, and the lift amount L of the valve 5 is reduced to zero.
As shown in FIG. 4B, when the rotation of the camshaft 22 advances and the contact position of the second rotating cam 21 with respect to the intervening roller 41 shifts from the nose 21c to the base circle 21a through the nose gradually decreasing portion 21d (first). Depending on the shape, size and arrangement phase of the one-rotation cam 20, the second rotation cam 21, the seesaw arm 7, the first roller 9, the second roller 10, and the control cam 36, the first rotation cam 20 and the first roller 9 Alternatively, the control cam 36 and the second roller 10 or both of them may be separated, but in the second embodiment to be described later, the interposing arm 37 is urged in the counterclockwise direction by a member (not shown). Therefore, it rotates with the control cam 36 by a small angle in the counterclockwise direction. Accordingly, the contact position of the second roller 10 with respect to the control cam 36 shifts from the concave surface portion 36c to the cylindrical surface portion 36a via the boundary portion 36b, and the second roller 10 returns to the maximum pressed position. At this time, the contact position of the first roller 9 with respect to the first rotating cam 20 shifts from the nose 20c to the base circle 20a via the nose gradually decreasing portion 20d, so that the lift amount of the valve 5 is maintained at zero.
[0035]
Next, FIGS. 5 (a) → (b) → (c) show the relative angles of the intervening arm 37 and the control cam 36 under the driving conditions that require a minute lift amount and a minute working angle, and the action due to this. .
As shown in FIG. 5A, when the first rotating cam 20 is in sliding contact with the first roller 9 at the boundary between the base circle 20a and the nose gradually increasing portion 20b, the latter half of the base circle 21a is in sliding contact with the intervening roller 41. As in FIG. 3A, the intervening arm 37 and the control cam 36 are stagnant at the small angle rotation start position. However, at this time, since the relative angle of the control cam 36 with respect to the intervening arm 37 is controlled by the relative angle control device so as to realize the minute lift amount and the minute working angle, the orientation of the control cam 36 at the small angle rotation start position is controlled. The orientation angles of the corners, specifically, the cylindrical surface portion 36a, the boundary portion 36b, and the concave surface portion 36c are shifted in the clockwise direction in FIG. 5A compared to FIG. 3A. The second roller 10 is close to the boundary 36b (slidably contacts in the second embodiment described later), and has reached the vicinity of the maximum pressing position. However, since the first roller 9 is at the uppermost position, the lift of the valve 5 is It has not occurred.
As shown in FIG. 5B, when the nose gradually increasing portion 20b presses the first roller 9 to increase the lift amount of the valve 5, the nose gradually increasing portion 21b presses the intervening roller 41 and the intervening arm. 37 and the control cam 36 begin to rotate in the clockwise direction by a small angle, and accordingly, the orientation (or contact) position of the second roller 10 with respect to the control cam 36 moves from the boundary portion 36b to the concave portion 36c. At this time, the first roller 9 is further pressed, but the second roller 10 moves upward, so that the lift amount L and the operating angle of the valve 5 are both small (see FIG. 7).
As shown in FIG. 5 (c), when the first roller 9 is pressed by the rear half of the nose 20c, the intervening roller 41 receives maximum pressing by the nose 21c, and the intervening arm 37 and the control cam 36 are moved. Stops at the small-angle rotation end position. At that time, since the second roller 10 moves from the boundary portion 36b to the concave surface portion 36c, the second roller 10 is greatly raised. At this time, the first roller 9 has reached the maximum pressing position, but since the second roller 10 side of the seesaw arm 7 is greatly raised, the rocker arm 1 swings upward and the lift amount of the valve 5 decreases to zero.
[0036]
Note that, in an operating situation where an intermediate lift amount / working angle between FIGS. 3 and 5 is required, the relative angle between the intermediate arm 37 and the control cam 36 between FIGS. Thus, an intermediate lift amount / working angle is obtained continuously or in multiple stages as shown in FIG.
[0037]
Next, FIGS. 6 (a) → (b) → (c) show the relative angles of the intervening arm 37 and the control cam 36 under an operating condition where lift stop is necessary, and the action due to the relative angles. As shown in FIG. 6A, when the first rotating cam 20 is in sliding contact with the first roller 9 at the boundary between the base circle 20a and the nose gradually increasing portion 20b, the latter half of the base circle 21a is in sliding contact with the intervening roller 41. As in FIGS. 3A and 5A, the intervening arm 37 and the control cam 36 are stagnant at the small angle rotation start position. However, at this time, since the relative angle of the control cam 36 with respect to the intervening arm 37 is controlled by the relative angle control device so as to realize the lift pause, the orientation angle of the control cam 36 at the small angle rotation start position, that is, the cylindrical surface portion. The orientation angles of 36a, the boundary portion 36b, and the concave surface portion 36c are further shifted in the clockwise direction in FIG. 6A than in FIG. 5A. At this time, the second roller 10 is oriented to the concave surface portion 36c (in sliding contact with the second embodiment described later), and the lift of the valve 5 does not occur because the first roller 9 is at the uppermost position.
As shown in FIG. 6B, even when the pressure of the first roller 9 by the nose gradually increasing portion 20b advances, the pressure of the intervening roller 41 by the nose gradually increasing portion 21b starts, and the intervening arm 37 and the control cam 36 are small in the clockwise direction. Angular rotation is started and the second roller 10 begins to slidably contact the concave surface portion 36c. At this time, the lift amount L and the operating angle of the valve 5 are both maintained at 0, and the lift is stopped.
As shown in FIG. 6C, even if the nose 20c presses the first roller 9 to the maximum pressing position, the nose gradually increasing portion 21b or the nose 21c presses the intervening roller 41, and the intervening arm 37 and the control cam 36 are moved. Since the second roller 10 is rotated by a small angle to the small-angle rotation end position, the second roller 10 is allowed to slide and contact with the central portion of the concave surface portion 36c, so that the valve 5 does not lift.
[0038]
Next, a second embodiment of the variable valve mechanism embodying the present invention will be described with reference to FIG. 8 only for parts different from the first embodiment. FIG. 8 is obtained by adding a mechanical adjuster 50 as an adjuster to the variable valve mechanism of the first embodiment.
[0039]
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.
[0040]
In the first embodiment, there is a case where a gap is formed between the roller and the cam as described above. However, in this embodiment, the lost motion spring 54 and the bottomed member 51 and the bottomed body are provided as shown in FIG. 8 by adding the mechanical adjuster 50. 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.
[0041]
Next, the third embodiment of the variable valve mechanism embodying the present invention will be described with reference to FIGS. 9 to 15 and only different portions from the first embodiment and the second embodiment. FIG. 9 shows a control valve 36 having a concave surface protruding from the variable valve mechanism of the first embodiment.
[0042]
In the present embodiment, the outer peripheral surface of the control cam 36 includes a protruding portion 36d extending in the tangential direction from the cylindrical surface portion 36a. A concave surface that smoothly connects from the cylindrical surface portion 36 a is formed on the lower surface of the projecting portion 36 d, forming a concave surface portion 36 e having a radius of curvature larger than the radius of the second roller 10, and curved in a direction away from the support shaft 30. Therefore, 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 to the concave surface portion 36e, and the contact position is concave. The amount of pressing of the second roller 10 by the control cam 36 increases as it moves to the tip of the portion 36e.
[0043]
As for the shape of the 1st rotation cam 20, the nose 20c used as the maximum protrusion amount is narrower in this embodiment than in the first embodiment. In this embodiment, since the shape of the first rotary cam 20 is strongly reflected in the lift amount graph of the valve 5, this is a change for shortening the maximum lift state.
[0044]
Compared with the first embodiment, the second rotating cam 21 has a significantly reduced nose protrusion. This is because the present embodiment can achieve the same effect as the first embodiment even if the small angle rotation amount of the intervening arm 37 and the control cam 36 is reduced compared to the first embodiment. It can be made compact.
[0045]
The relief groove 42 in the first embodiment is unnecessary because the nose of the second rotating cam 21 is reduced in this embodiment compared to the first embodiment and does not interfere with the cylindrical surface portion 36a of the interposing arm 37.
[0046]
The lengths of the intervening arm 37 and the camshaft 22 are shorter in this embodiment than in the first embodiment. This is a relief groove 42 that had to be formed so as not to interfere with the relative angle control device inside the intervening arm 37, and a concave portion that had to be formed so as not to interfere with the relative angle control device inside the control cam 36. This eliminates the need for 36c, thereby making the entire mechanism compact.
[0047]
With the above configuration, in the first embodiment, the second roller 10 enters the concave surface portion 36c formed in the control cam 36 and acts to reduce the lift amount of the valve 5, but in this embodiment, the control cam 36 A concave surface portion 36e formed on the protruding protrusion 36d acts in a direction in which the second roller 10 is pushed down and the lift amount of the valve 5 is increased. Accordingly, in the present embodiment, both the first rotary cam 20 and the second rotary cam 21 act in the direction of increasing the lift amount of the valve 5.
[0048]
When the control cam 36 is subjected to 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 provided in 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 formed in the protruding portion 36d is changed so that the pressing amount of the second roller can be changed.
[0049]
The variable valve mechanism configured as described above operates as follows.
First, FIGS. 12 (a) → (b) show the relative angles of the intervening arm 37 and the control cam 36 under the driving condition requiring the maximum lift, and the action due to the relative angles.
As shown in FIG. 12A, 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 is controlled so that the intervening arm 37 and the control cam 36 achieve the maximum lift, the concave surface portion 36e is close to the second roller 10 (sliding contact by applying the mechanical adjuster of the second embodiment). To do. This is because, as soon as the intervening arm 37 starts to rotate at a small angle, the concave surface portion 36e starts to press the second roller 10 and starts to lift the valve 5, so that the lift operating angle becomes maximum. 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. 12B, when the first roller 9 receives the maximum pressure by the nose 20c, the intervening roller 41 also receives the maximum pressure by the nose 21c, and the interposing arm 37 and the control cam 36 are small. Reach the end of angular rotation. At this time, since the concave surface portion 36e reaches the lowest position and restricts the ascent of the second roller 10 to the maximum, the seesaw arm 7 reaches the maximum pressing position, and the lift amount L of the valve 5 is generated and increased to reach the maximum lift amount Lmax. Also, the working angle of the lift is maximized as described above.
[0050]
Next, FIGS. 13 (a) → (b) show the relative angles of the intervening arm 37 and the control cam 36 under an operating condition that requires a minute lift, and the action due thereto.
As shown in FIG. 13A, 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 intervening arm 37 and the control cam 36 are controlled at a relative angle so as to realize a minute lift, the concave surface portion 36e is largely separated from the second roller 10, and the second roller 10 is also separated from the cylindrical surface portion 36a. (Sliding contact is applied by applying the mechanical adjuster of the second embodiment). At this time, if the intervening arm 37 is not displaced to the vicinity of the small-angle rotation end position, the concave surface portion 36e does not begin to press the second roller 10, so that the lift operating angle of the valve 5 becomes minute. 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. 13B, when the first roller 9 receives maximum pressure by the nose 20c, the intervening roller 41 also receives maximum pressure by the nose 21c, and the intervening arm 37 and the control cam 36 are small. Reach the end of angular rotation. At this time, since the concave surface portion 36e is at a higher position than that in FIG. 12 (b), the ascent restriction of the second roller 10 becomes slight. Therefore, the lift amount L of the valve 5 is generated and increased to reach the lift amount L. The lift operating angle is also small as described above.
[0051]
Note that, under an operating situation where an intermediate lift amount / working angle between FIGS. 12 and 13 is required, the relative angle between the intermediate arm 37 and the control cam 36 between FIGS. 12 and 13 is a relative angle control device. Thus, an intermediate lift amount / working angle is obtained continuously or stepwise as shown in FIG.
[0052]
Next, FIGS. 14 (a) → (b) show the relative angles of the intervening arm 37 and the control cam 36 under the operating condition that requires lift suspension and the action caused by the relative angle.
As shown in FIG. 14A, 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 is in sliding contact with the interposed roller 41, the interposed arm 37 and the control cam 36 are The first roller 9 is at the uppermost position with the small angle rotation start position. Since the intervening arm 37 and the control cam 36 are controlled relative to each other so as to realize the lift pause, the concave surface portion 36e is separated from the second roller 10 at the maximum, and the second roller 10 is also separated from the cylindrical surface portion 36a. (Same as above) 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. 14B, when the first roller 9 receives the maximum pressure by the nose 20c, the intervening roller 41 also receives the maximum pressure by the nose 21c, and the interposing arm 37 and the control cam 36 are small. Reach the end of angular rotation. At this time, the end position of the small angle rotation of the concave surface portion 36e reaches the highest position, and the second roller 10 rises to the maximum and is not restricted by the concave surface portion 36e, but comes into contact with the cylindrical surface portion 36a. The valve 5 is lifted.
[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.
[0054]
【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 one 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 cross-sectional view showing a main part of a relative angle control device in the mechanism.
FIG. 3 is a cross-sectional view showing the operation of the mechanism when the maximum lift amount and operating angle are required.
FIG. 4 is a cross-sectional view showing the operation following FIG. 3;
FIG. 5 is a cross-sectional view showing the operation of the mechanism when a minute lift amount and operating angle are required.
FIG. 6 is a cross-sectional view showing the operation of the mechanism when lift suspension is necessary.
FIG. 7 is a graph showing a lift amount and a working angle of a valve obtained by the same mechanism.
FIG. 8 is a cross-sectional view showing a variable valve mechanism according to a second embodiment of the present invention.
FIG. 9 is a perspective view showing a variable valve mechanism according to a third embodiment of the present invention.
FIG. 10 is a perspective view depicting the angle of FIG. 9 changed.
FIG. 11 is a cross-sectional view showing a main part of a relative angle control device in the mechanism.
FIG. 12 is a cross-sectional view showing the operation of the mechanism when the maximum lift amount and operating angle are required.
FIG. 13 is a cross-sectional view showing the operation of the mechanism when a minute lift amount and operating angle are required.
FIG. 14 is a cross-sectional view showing the operation of the mechanism when lift suspension is necessary.
FIG. 15 is a graph showing a lift amount and a working angle of a valve obtained by the same mechanism.
[Explanation of symbols]
1 Rocker arm 5 Valve 7 Seesaw arm 9 First roller 10 as first sliding contact portion Second roller 20 as second sliding contact portion First rotating cam 21 Second rotating cam 22 Cam shaft 30 Support shaft 36 Control cam 36c Concave surface portion 36e Concave surface portion 37 Intervening arm 41 Intervening roller 43 as intervening sliding contact portion Helical spline 44 Helical spline

Claims (5)

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 and a second rotating cam that is positioned next to the first rotating cam is rotatably supported, and above the second sliding contact portion. By providing the interposition member displaceably, when the second rotating cam rotates and acts on the interposition member, the interposition member is displaced and acts on the second sliding contact portion,
A variable valve provided with a relative angle control device that changes the lift amount and the working angle of the valve by changing the amount of action of the second sliding contact portion by the interposing member continuously or stepwise according to the operating condition of the internal combustion engine mechanism.   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 interposition member couples a control cam having a concave surface that presses the second slidable contact portion of the seesaw arm and an intervening arm having the intervening slidable contact portion pressed by the second rotating cam so that the relative angle can be changed. one small pivotably der those pivotally mounted to the support shaft is, the concave surface, the variable valve mechanism according to claim 1, wherein formed in the projecting portion projecting from the said control cam.   The variable valve mechanism according to claim 2 or 3, wherein the intervening sliding contact portion is a roller rotatably mounted on the intervening arm.   5. The variable valve mechanism according to claim 1, 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.

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