JP2014181581A - Variable valve mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable valve mechanism capable of easily adjusting the extremely small lift amount and opening timing of a valve.SOLUTION: A variable valve mechanism 1 includes an eccentric ring 32 that is externally fitted to a control shaft 31. The eccentric ring 32 is rotated with respect to the control shaft 31. Thus, a position of a swinging shaft center X2 of a swing arm 11 is shifted for fine adjustment of the lift amount and opening period of a valve 10.

Description

  The present invention relates to a variable valve mechanism that can change a lift amount and an open period of an intake / exhaust valve of an engine.

  Conventionally, a variable valve mechanism that can change the lift amount and opening period of an intake / exhaust valve of an engine is generally known. The variable valve mechanism includes an intake / exhaust valve, a camshaft that rotates in synchronization with the crankshaft of the engine, a control arm that is pressed and swung by the rotation of the camshaft, and a swing of the control arm. A swing arm that lifts the valve via a rocker arm by swinging around the rotational axis of the control shaft in conjunction with the operation, and a lift adjustment mechanism that changes the relative position of the control arm with respect to the swing arm; The lift adjusting mechanism is operated to change the pressing position of the control arm with respect to the swing arm to change the lift amount and the opening period of the valve.

  By the way, the variable valve mechanism as described above oscillates due to variations in the amount of air entering and exiting the combustion chamber of each cylinder due to manufacturing errors of each component and assembly errors during assembly, and the combustion of each cylinder varies accordingly. May cause fuel consumption and fuel consumption. Therefore, it is necessary to finely adjust the valve lift amount and the opening timing between the cylinders in advance so that the amount of air entering and exiting the combustion chamber of each cylinder does not vary.

  In order to cope with this, for example, in the variable valve mechanism disclosed in Patent Document 1, the tip of the screw member is brought into contact with the control arm, and the control arm is swung with the contact portion as a rocking fulcrum. Yes. Then, the screw member is screwed / retracted with respect to the control arm to change the position of the swing fulcrum, thereby changing the pressing position of the control arm with respect to the swing arm, thereby adjusting the lift amount and the opening timing. Fine adjustment.

JP 2009-14000 (paragraphs 0029 to 0040 column, FIGS. 1 and 4)

  However, in the variable valve mechanism as in Patent Document 1, the pressing position of the control arm with respect to the swing arm is set close to the pressing position of the swing arm with respect to the rocker arm, and the lift of the valve with respect to the change amount of the pressing position of the control arm. Since the ratio of the change amount of the state is large, when the lift position of the valve is adjusted by directly changing the pressing position of the control arm as in Patent Document 1, the lift state of the valve changes greatly, and the amount of change is extremely small. Adjustment of the lift amount and opening time of the valve is time consuming and complicated.

  The present invention has been made in view of such points, and an object of the present invention is to provide a variable valve mechanism that can easily adjust the lift amount and opening timing of a very small valve. .

  In order to achieve the above object, the present invention is characterized by finely adjusting the lift amount and opening timing of the valve by devising how to change the position of the swing arm.

  That is, in the first invention, the intake / exhaust valve, the camshaft that rotates in synchronization with the crankshaft of the engine, and the shaft that extends in the same direction as the axis of the camshaft are provided so as to be swingable. A control arm that is pressed and swung by the rotating operation of the camshaft, and is swingable about an axis that extends in the same direction as the axis of the camshaft, and is pressed by the swinging operation of the control arm. A swing arm that swings and lifts the valve directly or indirectly by the swing operation and a relative position of the control arm with respect to the swing arm to change the control arm relative to the swing arm. Lift adjusting means for adjusting the lift amount and opening period of the valve by changing the pressing position; By moving the position of the pivot axis of the arm, characterized in that it comprises a lift fine adjustment means for finely adjusting the lift amount and the opening period of the valve.

  According to a second invention, in the first invention, the lift adjusting means is provided integrally with a control shaft that rotates about an axis extending in the same direction as the axis of the camshaft, and is integrally provided with the control shaft. And an adjusting lever having a protruding portion that protrudes radially outward of the control shaft and pivotally supports the control arm, and the adjusting lever rotates around the axis of the control shaft together with the control shaft. Thus, as seen from the axial direction of the camshaft, the swing axis of the control arm is moved in a direction to make contact with and away from the swing axis of the swing arm.

  According to a third aspect, in the first or second aspect, the peripheral portion of the swing axis of the swing arm is in the axial direction of the camshaft with respect to the peripheral portion of the swing axis of the control arm. It is characterized by being displaced.

  According to a fourth invention, in any one of the first to third inventions, when the valve is closed, the swing axis of the control arm is the swing arm when viewed from the axial direction of the camshaft. It is located on the straight line which passes the rocking | fluctuation shaft center and the pressing position of the said control arm with respect to the said swing arm, or its vicinity.

  According to a fifth invention, in any one of the first to fourth inventions, a pair of the valves are arranged in parallel in the axial direction of the camshaft in the same cylinder of the engine, and the swing arms are connected to the valves. Correspondingly, a pair of control arms are provided, and the control arm is provided integrally with the main body disposed between the swing arms in the axial direction of the camshaft, and presses the swing arms. And a pair of pressing portions.

  According to a sixth aspect, in the fifth aspect, the shapes of the pressing portions for pressing the swing arm of the control arms are different from each other.

  In a seventh invention, in any one of the second to sixth inventions, the fine lift adjustment means is externally fitted to the control shaft so as to be rotatable about the axis of the control shaft, and the outer peripheral surface is the above-mentioned The swing arm includes an eccentric ring that contacts an outer surface around the swing axis.

  In an eighth aspect based on the seventh aspect, the fine lift adjustment means further includes biasing means for biasing the eccentric ring toward the adjustment lever in the axial direction of the control shaft, and the adjustment lever includes: An annular ridge extending around the control shaft is provided, and a plurality of same-shaped engagement protrusions are provided in the circumferential direction on either the end surface of the eccentric ring on the adjustment lever side or the side surface of the annular ridge. A plurality of engaging recesses of the same shape are provided at equal intervals in the circumferential direction, and the eccentric rings are provided at equal intervals on one of the other sides. Is rotated against the urging force of the urging means to change the circumferential position of the eccentric ring with respect to the control shaft.

  According to a ninth invention, in any one of the second to sixth inventions, the fine lift adjustment means is detachably attached to the outer peripheral surface of the control shaft on the swing arm side, and is attached to the outer peripheral surface of the control shaft. In this state, the outer peripheral surface is a C-shaped shim that contacts the outer surface around the swing axis of the swing arm at a position where the outer peripheral surface protrudes outward from the outer peripheral surface of the control shaft.

  According to a tenth invention, in the ninth invention, a pair of locking projections are provided on either one of the inner peripheral side end portions of the C-shaped shim and the outer peripheral surface of the control shaft. The other is provided with a pair of locking recesses for locking the locking protrusions.

  In the first aspect of the invention, since the swing arm swing axis is located farther from the swing arm valve pressing position than the control arm pressing position with respect to the swing arm, the control arm is moved directly around the swing axis. If the change in the position of the swing arm's pivot axis and fine adjustment of the lift state of the valve are larger than the fine adjustment of the lift state of the valve by turning, the change in the pressing position of the swing arm with respect to the valve is greater. Therefore, it is possible to easily adjust the lift amount of the valve and the opening timing.

  In the second invention, when the swing axis of the control arm is brought close to the swing axis of the swing arm, the relative position of the control arm with respect to the swing arm shifts when the control arm and the swing arm swing. Therefore, the sliding amount of the control arm with respect to the swing arm can be reduced as compared with a variable valve mechanism in which the distance between the swing axis of the control arm and the swing axis of the swing arm is constant.

  In the third aspect of the invention, since the peripheral portion of the swing axis of the swing arm overlaps the peripheral portion of the swing axis of the control arm when viewed from the axial direction of the camshaft, the swing axis of the control arm is swung. When approaching the swing axis of the arm, the distance between the swing axis of the swing arm and the swing axis of the control arm can be shortened.

  In the fourth aspect of the invention, when the control arm presses the swing arm, the pressing position of the control arm with respect to the swing arm is hardly changed, and the sliding amount of the control arm with respect to the swing arm can be further reduced.

  In the fifth invention, since there is one control arm for a pair of swing arms, the distance between two valves in the same cylinder is shortened, and a compact variable valve mechanism can be achieved. Further, by integrally forming the control arm, the rigidity can be increased and the manufacturing cost can be reduced.

  In the sixth aspect of the invention, the lift characteristics of the two valves in the same cylinder can be made different from each other, so that it can flexibly correspond to the engine specifications.

  In the seventh invention, when the eccentric ring is rotated with respect to the control shaft, the position of the outer peripheral surface of the eccentric ring changes in the radial direction of the control shaft by an amount corresponding to the eccentricity of the eccentric ring. Since the position of the outer surface around the center moves, the position of the swing axis of the swing arm can be easily changed.

  In the eighth invention, when the eccentric ring is rotated with respect to the control shaft, the movement of the eccentric ring around the axis of the control shaft can be restricted by engaging the engagement protrusion with the engagement recess. In addition, since the engagement protrusion and the engagement recess are respectively in the same shape and formed at equal intervals, by rotating the eccentric ring and changing each engagement protrusion to be engaged with each engagement recess, The eccentric ring can be rotated quantitatively. Further, when rotating the eccentric ring, if the eccentric ring is separated from the adjustment lever against the urging force of the urging means, each engaging projection is detached from each engaging recess, so that the eccentric ring is On the other hand, when the eccentric ring is rotated with respect to the control shaft and each engagement protrusion is engaged with each engagement recess, the eccentric ring and the adjustment lever are Since they are in close contact with each other, the eccentric ring can be firmly fixed to the control shaft.

  In the ninth aspect of the invention, by changing the thickness of the C-shaped shim, the position of the outer peripheral surface of the C-shaped shim changes in the radial direction of the control shaft. Therefore, the position of the swing axis of the swing arm can be easily changed.

  In the tenth invention, when the C-shaped shim is attached to the control shaft, the position of the C-shaped shim does not shift with respect to the control shaft, and the attachment of the C-shaped shim to the control shaft can be stabilized.

It is a perspective view of the variable valve mechanism based on Embodiment 1 of this invention. It is the figure which looked at the variable valve mechanism from the axial center direction of a cam shaft, and shows the state which the valve closed in the large lift state. It is the figure which looked at the variable valve mechanism from the axial center direction of a cam shaft, and shows the state which the valve opened to the maximum in the large lift state. It is the figure which looked at the variable valve mechanism from the axial center direction of a cam shaft, and shows the state which the valve closed in the small lift state. It is the figure which looked at the variable valve mechanism from the axial center direction of a cam shaft, and shows the state which the valve opened to the maximum in the small lift state. It is a graph which shows the relationship between the rotation angle of a rotating cam, and the lift amount of a valve | bulb. FIG. 3 is an enlarged view around a control shaft in FIG. 2. It is the figure which looked at the variable valve mechanism from the axial direction of the camshaft, and shows a state immediately before the control arm swings due to the rotation of the camshaft in the zero lift state. It is the figure which looked at the variable valve mechanism from the axial direction of the camshaft, and shows the state immediately after the control arm swings due to the rotation of the camshaft in the zero lift state. FIG. 3 is a view corresponding to FIG. 2 according to the second embodiment. FIG. 3 is a view as seen from an arrow A in FIG. 2. FIG. 8 is a diagram corresponding to FIG. 7 according to the third embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiment is merely exemplary in nature.
Embodiment 1 of the Invention
1 and 2 show a variable valve mechanism 1 according to Embodiment 1 of the present invention. The variable valve mechanism 1 is applied to the intake side of an engine (not shown) employing a four-valve double overhead cam system, and is used for intake air provided in an opening portion (not shown) of an intake port. And a camshaft 2 that rotates in synchronization with an engine crankshaft (not shown).

  The camshaft 2 is rotatably supported around an axis X1 by a cylinder head (not shown) of an engine so as to extend in the same direction as a crankshaft (not shown).

  The camshaft 2 is provided with a plurality of rotating cams 3 at a predetermined interval in the direction of the axis X1, and the rotating cam 3 protrudes in a radial direction from the base circle 3a and the base circle 3a. And a cam nose portion 3b.

  A pair of the valves 10 are arranged in parallel in the direction of the axis X1 of the camshaft 2 in the same cylinder of the engine, and an umbrella portion 10a that opens and closes an intake port (not shown), and the camshaft 2 side from the umbrella portion 10a And a shaft portion 10b extending obliquely upward. A valve spring (not shown) is provided around the shaft portion 10b, and the valve 10 is urged upward by the valve spring.

  A pair of rocker arms 41 for lifting the valves 10 are provided above the valves 10.

  The rocker arm 41 has a shape extending in the substantially horizontal direction from the upper end of the shaft portion 10b of the valve 10 to the side opposite to the camshaft 2 so as to intersect the axial center direction of the camshaft 2, and a rotation shaft is provided in the middle portion thereof. A roller 42 whose center is in the axial direction of the camshaft 2 is rotatably provided.

  The end of the rocker arm 41 on the side opposite to the camshaft 2 is supported by a hydraulic lash adjuster 43 through a spherical pivot structure, and the rocker arm 41 swings around the supporting portion as a fulcrum. The end of the rocker arm 41 on the camshaft 2 side presses the upper end of the shaft portion 10b of the valve 10 downward so that the valve 10 is lifted.

  A pair of swing arms 11 corresponding to each rocker arm 41 is provided above each rocker arm 41, and the swing arm 11 has a shape extending obliquely upward on the side opposite to the camshaft 2 from above the roller 42. ing.

  The swing arm 11 includes a pair of side plate portions 11a facing each other at a predetermined interval in the axial direction of the camshaft 2, and an axial center X1 of the camshaft 2 is provided at an upper end portion of the both side plate portions 11a. Is provided with a swing shaft 11b extending in the same direction.

  Around the swing shaft 11b, a roller 12 that rotates around the swing shaft 11b is provided, and the swing arm 11 is configured to be swingable around the swing shaft 11b (swing axis X2). Has been.

  On the other hand, a first pressing portion 11d that bridges both the lower ends is provided at the lower end of the both side plate portions 11a.

  The first pressing portion 11d has a curved shape with a midway portion positioned upward as viewed from the direction of the axis X1 of the camshaft 2, and contacts the roller 42 of the rocker arm 41 at a point P (pressing position). Yes.

  In addition, a curved surface portion 11e that curves upward when viewed from the direction of the axis X1 of the camshaft 2 is formed at the lower edge on the lower edge of each side plate portion 11a.

  Further, a connecting shaft 11c for connecting the both side plate portions 11a is provided near the lower end of the both side plate portions 11a.

  A control shaft 31 extending in the same direction as the axis X1 of the camshaft 2 is supported on a cylinder head (not shown) so as to be rotatable around the axis X4. ing.

  The control shaft 31 is integrally provided with an adjustment lever 33 for changing the lift amount and opening timing of the valve 10, and the adjustment lever 33 and the control shaft 31 constitute the lift adjustment means of the present invention. Yes.

  The adjustment lever 33 includes an annular protrusion 33b extending around the control shaft 31, and a protrusion 33c protruding outward in the radial direction of the control shaft 31 between the upper ends of the swing arms 11. A rotation shaft 33a extending in the direction of the axis X1 of the camshaft 2 is rotatably provided on the protrusion 33c.

  A pair of eccentric rings 32 are fitted on the control shaft 31 so as to correspond to the rollers 12.

  As shown in FIG. 10, each eccentric ring 32 has a crown gear shape and is movable in the axial direction of the control shaft 31.

  Each eccentric ring 32 is in contact with the outer peripheral surface of each roller 12 (the outer surface around the swing axis of the swing arm 11) from below, and rotates about the axis X4 of the control shaft 31. It is possible.

  Furthermore, a plurality of teeth 32b (engagement protrusions) and tooth grooves 32c having the same shape are provided alternately at equal intervals in the circumferential direction on the end face of each eccentric ring 32 on the adjustment lever 33 side.

  In addition, a plurality of circular holes 32d for inserting a tool when rotating the eccentric ring 32 are formed at equal intervals in the circumferential direction near the adjustment lever 33 of each eccentric ring 32.

  On the other hand, a plurality of teeth 33d and tooth grooves 33e (engaging recesses) respectively corresponding to the teeth 32b and the tooth grooves 32c of the eccentric ring 32 are provided on the side surface of the annular protrusion 33b of the adjusting lever 33 in the circumferential direction. The teeth 32b of the eccentric ring 32 are provided at equal intervals alternately, the teeth 33b of the annular ridge 33b and the teeth 33d of the annular ridge 33b are teeth 32c of the eccentric ring 32, respectively. It is adapted to engage with and disengage.

  The control shaft 31 is provided with a spring member 6 (biasing means) formed by bending one spring steel.

  The spring member 6 includes a pair of straight portions 6a extending parallel to the direction of the axis X4 of the control shaft 31, and a pair of curved portions 6b curved in a U shape along the circumferential direction of the outer peripheral surface of the control shaft 31. And each end of one curved portion 6b continues to one end of each of the straight portions 6a, and each end of the other curved portion 6b continues to the other end of each of the straight portions 6a. ing.

  The bending portion 6b is configured to exhibit a spring function by changing the angle of the bending portion 6b with respect to the straight portion 6a, and each bending portion 6b is provided on the counter adjustment lever 33 side of each eccentric ring 32. The open end is urged toward the adjustment lever 33 in the direction of the axis X4 of the control shaft 31.

  Then, by rotating the eccentric ring 32 against the urging force of the spring member 6, the circumferential position of the eccentric ring 32 with respect to the control shaft 31 is changed as shown in FIG. Yes.

  Above both the swing arms 11, there is provided a substantially T-shaped control arm 21 as viewed from above (see FIG. 1).

  The control arm 21 includes a main body portion 21a that extends in a substantially horizontal direction so as to intersect with the axial center X1 direction of the camshaft 2, and the main body portion 21a has the two swings in the axial center X1 direction of the camshaft 2. Arranged between the arms 11.

  That is, the peripheral part of the axis X2 of the swing arm 11 is arranged so as to be shifted in the axial direction of the camshaft 2 with respect to the peripheral part of the swing axis X3 of the control arm 21.

  The end of the main body 21a on the side opposite to the camshaft 2 is pivotally attached to the rotation shaft 33a of the protrusion 33c, and the main body 21a can swing around the swing axis X3 of the rotation shaft 33a. It has become.

  At the end of the main body 21a on the camshaft 2 side, a second pressing portion 21b having a substantially U-shaped cross section that opens obliquely upward on the camshaft 2 side is spaced apart in the direction of the axis X1 of the camshaft 2. A pair is provided.

  The second pressing portions 21b are provided integrally with the main body portion 21a, and the lower end side of the second pressing portion 21b forms a flat surface and is in contact with the curved surface portion 11e of the swing arm 11.

  Inside each second pressing portion 21b, a roller 22 having a rotation axis oriented in the direction of the axis X1 of the camshaft 2 is rotatably provided, and an outer peripheral surface of each roller 22 corresponds to each roller 22. The rotating cam 3 is in contact with the outer peripheral surface from below.

  Above the upper ends of the swing arms 11, a rectangular fixed block 51 extending in the direction of the axis X1 of the camshaft 2 is fixed to an engine cylinder head (not shown).

  A pair of support blocks 51a whose lower surfaces are in contact with the outer peripheral surfaces of the respective swing shafts 11b project from the positions corresponding to the respective swing shafts 11b on the lower surface of the fixed block 51, and are formed at the lower ends of the support blocks 51a. A groove 51b having a concave cross section that is inclined downward toward the opposite camshaft 2 side is formed.

  Both the support blocks 51a support the swing shaft 11b with the eccentric ring 32. In this support state, the swing center of the swing arm 11 is the swing shaft center of the swing shaft 11b. X2 is decided.

  A pair of torsion coil springs 52 corresponding to the respective swing arms 11 are disposed on the side of the fixed block 51 opposite to the camshaft 2.

  One end of each torsion coil spring 52 is fixed to the fixed block 51, while the other end is hooked on the connecting shaft 11c of the swing arm 11 from below to urge the swing arm 11 upward.

  Then, the camshaft 2 rotates in synchronization with a crankshaft of an engine (not shown), and as shown in FIGS. 3 and 5, the cam nose portion 3b of the rotating cam 3 moves the roller 22 upward as the camshaft 2 rotates. , The control arm 21 pivots downward about the rotation shaft 33a, so that the second pressing portion 21b of the control arm 21 resists the biasing force of the torsion coil spring 52 and The curved surface portion 11e is pressed downward.

  Further, the swing arm 11 pressed downward on the curved surface portion 11e rotates downward about the swing shaft 11b, and the first pressing portion 11d of the swing arm 11 moves the roller 42 of the rocker arm 41 downward. It is designed to be pressed.

  Further, the rocker arm 41 having pressed the roller 42 downward is rotated downward with the end of the rocker arm 41 on the side opposite to the camshaft 2 as a fulcrum. The end of the rocker arm 41 on the camshaft 2 side presses the upper end of the shaft portion 10b of the valve 10, whereby the valve 10 is lifted and an intake port (not shown) is opened.

  In addition, the roller 42 is pressed by substantially half of the first pressing portion 11d of the swing arm 11 on the camshaft 2 side to lift the valve 10, and this portion is hereinafter referred to as an action portion 11f.

  On the other hand, when the camshaft 2 further rotates and the cam nose portion 3b of the rotating cam 3 does not press the roller 22 from above, the torsion coil spring 52 and the valve (not shown) are shown in FIGS. The swing arm 11 is rotated upward by the urging force of the spring, and the control arm 21 is also rotated upward in conjunction with the movement, whereby the rocker arm 41 and the valve 10 are returned to their original positions. An intake port (not shown) is closed.

  Further, when the control shaft 31 is rotated about the axis X4 and the adjusting lever 33 is rotated, the rotation shaft 33a (oscillation axis X3) becomes the oscillation axis 11b (oscillation axis) of the swing arm 11. When the valve 10 is in a closed state, the swing axis X3 of the control arm 21 when the valve 10 is closed is the swing axis X3 of the control arm 21. It is located on or near the straight lines L1 and L2 (see FIGS. 2 and 4) passing through the dynamic axis X2 and the pressing position of the control arm 21 against the swing arm 11.

  The positional relationship between the camshaft 2 and the roller 22 of the control arm 21 and the second pressing portion 21b of the control arm 21 and the above are determined by the contact and separation between the swing axis X2 and the swing axis X3. The positional relationship between the swing arm 11 and the curved surface portion 11e changes, and the change of the relative position of the control arm 21 with respect to the swing arm 11 changes the position of the second pressing portion 21b against the curved surface portion 11e. As the distance to the rotation shaft 33a (swing axis X3) changes, the angular position of the swing arm 11 before turning (that is, the swing start angle position) changes, and the first pressing portion 11d The pressing position P against the roller 42 is changed.

  When the adjustment lever 33 is rotated counterclockwise, the rotation shaft 33a (swing axis X3) gradually moves away from the roller 12 (swing axis X2) of the swing arm 11, and the second pressing portion. The distance between the pressing position of 21b against the curved surface portion 11e and the rotating shaft 33a is gradually increased. Then, the pressing position P of the first pressing portion 11d against the roller 42 is shifted to the camshaft 2 side, and when the camshaft 2 is rotated as shown in FIGS. 2 and 3, the first pressing portion 11d against the roller 42 is rotated. The pressure position P of the valve 10 is greatly applied to the action portion 11f, whereby the lift amount and the open period of the valve 10 are maximized, so that a so-called large lift state is achieved.

  The relationship between the rotation angle of the rotary cam 3 and the lift amount of the valve 10 in the large lift state is as shown by a lift curve C1 in FIG.

  The maximum counterclockwise rotation position of the adjustment lever 33 is such that the swing axis X3 of the control arm 21 is relative to the swing axis X2 of the swing arm 11 when viewed from the direction of the axis X1 of the camshaft 2. Even if it is set to a position within a predetermined distance and is in a large lift state, as shown in FIG. 3, the second pressing portion 21b is curved when the second pressing portion 21b presses the curved surface portion 11e. The sliding amount d with respect to the surface part 11e is small.

  The predetermined distance is preferably as small as possible. For example, when the valve 10 is closed in the large lift state, the predetermined distance is the same as that of the swing axis X2 of the swing arm 11 when viewed from the direction of the axis X1 of the camshaft 2. It is good also as a distance between the press position with respect to the curved surface part 11e of the 2 press part 21b.

  Further, a line R1 indicated by a one-dot chain line in FIG. 3 passes through a pressing position of the second pressing portion 21b with respect to the curved surface portion 11e in a state before the control arm 21 is rotated by the rotating cam 3 (a closed state of the valve 10). A line R2 indicated by a two-dot chain line in a state where the control arm 21 is rotated to the maximum by the rotary cam 3 (a state where the valve 10 is lifted to the maximum). The arc is centered on the swing axis X3 and passes through the pressing position of the second pressing portion 21b with respect to the curved surface portion 11e. Is the sliding amount d.

  On the other hand, when the adjusting lever 33 is rotated clockwise until the state shown in FIGS. 4 and 5, the rotating shaft 33a (swing axis X3) gradually moves to the roller 12 (rotating axis X2) of the swing arm 11. The distance between the rotary shaft 33a and the pressing position of the second pressing portion 21b with respect to the curved surface portion 11e gradually decreases. Then, the pressing position P of the first pressing portion 11d with respect to the roller 42 shifts to the side opposite to the camshaft 2, and when the camshaft 2 rotates, the pressing position P of the first pressing portion 11d with respect to the roller 42 becomes the acting portion 11f. Thus, the lift amount and the open period of the valve 10 are minimized, so that a so-called small lift state is achieved.

  The relationship between the rotation angle of the rotary cam 3 and the lift amount of the valve 10 in the small lift state is as shown by a lift curve C2 in FIG.

  Then, when the swing axis X3 of the control arm 21 approaches the swing axis X2 of the swing arm 11, the curved surface portion 11e of the second pressing portion 21b when the second pressing portion 21b presses the curved surface portion 11e. The sliding amount d with respect to is small.

  As the adjustment lever 33 is rotated, the lift curve at each rotation position changes between the lift curve C1 and the lift curve C2, as shown in FIG. S1 (a line indicated by a one-dot chain line) connected over the lift curve approximates a straight line.

  Further, the adjusting lever 33 can be further rotated clockwise from the state of FIGS. 4 and 5 to bring the axis X3 of the control arm 21 closer to the axis X2 of the swing arm 11, which is shown in FIG. As described above, the distance between the pressing position of the second pressing portion 21b with respect to the curved surface portion 11e and the swing axis X3 of the control arm 21 is further smaller than in the small lift state, and the first pressing portion 11d with respect to the roller 42 has a smaller distance. The pressing position P is further away from the action portion 11f than in the small lift state. In this state, as shown in FIG. 9, even if the camshaft 2 rotates and the second pressing portion 21 b of the control arm 21 presses the curved surface portion 11 e of the swing arm 11, the first pressing portion 11 d against the roller 42 Since the pressing position P is not applied to the action portion 11f, the rocker arm 41 does not operate and is in a so-called zero lift state.

  Further, as shown in FIG. 7, when the eccentric ring 32 is rotated with respect to the control shaft 31, when viewed from the direction of the axis X1 of the camshaft 2, the center axis X5 of the roller 42 and the groove 51b of the support block 51a The swing shaft 11b of the swing arm 11 moves along the groove 51b of the support block 51a so that the distance D (see FIG. 2) between the contact position of the rollers 12 does not change (imaginary line). reference). That is, by rotating the eccentric ring 32, the position of the valve 10 does not change even if the swing shaft 11b of the swing arm 11 is moved.

  Then, by the movement of the swing shaft 11b of the swing arm 11, the pressing position of the second pressing portion 21b of the control arm 21 with respect to the curved surface portion 11e of the swing arm 11 is changed, and the lift amount and the opening period of the valve 10 are slightly changed. It has come to be adjusted.

  Note that the movement of the swing shaft 11b of the swing arm 11 so that the distance D does not change not only means that the swing shaft 11b of the swing arm 11 moves so that the distance D does not change at all. The distance D is slightly changed, and the swing shaft 11b of the swing arm 11 is moved. In the first embodiment, when the eccentric ring 32 is rotated with respect to the control shaft 31, the end on the swing axis X2 side of the swing arm 11 moves in the inclination direction of the groove 51b. D slightly changes, but its value is very small, so it does not matter.

  As described above, according to the first embodiment of the present invention, when the lift state of the valve 10 is finely adjusted by the eccentric ring 32, the swing axis X2 of the swing arm 11 swings more than the pressing position of the control arm 21 against the swing arm 11. Since the rocker arm 41 of the arm 11 is located away from the pressing position P (pressing position with respect to the valve 10) with respect to the roller 42, the control arm 21 is directly rotated around the swing axis X3 to slightly change the lift state of the valve 10. Rather than adjusting, changing the position of the swing axis X2 of the swing arm 11 to finely adjust the lift state of the valve does not increase the change in the pressing position P against the roller 42 in the rocker arm 41 of the swing arm 11, The lift amount and opening time of the valve 10 can be easily adjusted.

  Further, when the swing axis X3 of the control arm 21 is brought close to the swing axis X2 of the swing arm 11, the control arm 21 with respect to the swing arm 11 moves when the control arm 21 and the swing arm 11 swing. Since the relative position is difficult to shift, the distance between the swing axis X3 of the control arm 21 and the swing axis X2 of the swing arm 11 is larger than that of the variable valve mechanism in which the distance between the swing arm 11 and the swing arm 11 is constant. The sliding amount d can be reduced.

  Further, since the peripheral portion of the swing axis X2 of the swing arm 11 overlaps the peripheral portion of the swing axis X3 of the control arm 21 when viewed from the axial center X1 direction of the camshaft 2, the swing shaft of the control arm 21 is overlapped. When the center X3 is brought closer to the swing axis X2 of the swing arm 11, the distance between the swing axis X2 of the swing arm 11 and the swing axis X3 of the control arm 21 can be shortened.

  Further, in the closed state of the valve 10, the swing axis X3 of the control arm 21 is located on or near the straight lines L1, L2, so that when the control arm 21 presses the swing arm 11, the swing The pressing position of the control arm 21 with respect to the arm 11 is hardly changed, and the sliding amount d of the control arm 21 with respect to the swing arm 11 can be further reduced.

  Further, since there is one control arm 21 for the pair of swing arms 11, the distance between two valves in the same cylinder is shortened, and a compact variable valve mechanism 1 can be obtained. Further, by integrally molding the control arm 21, the rigidity can be increased and the manufacturing cost can be reduced.

  When the eccentric ring 32 is rotated with respect to the control shaft 31, the position of the outer peripheral surface of the eccentric ring 32 changes in the radial direction of the control shaft 31 as much as the eccentric ring 32 is eccentric. Since the position of the outer surface around the swing axis X2 of the swing arm 11 moves, the position of the swing axis X2 of the swing arm 11 can be easily changed.

Further, when the eccentric ring 32 is rotated with respect to the control shaft 31, each tooth 32b is engaged with each tooth groove 33e, and each tooth 33d is engaged with each tooth groove 32c, whereby the eccentric ring with respect to the control shaft 31 is engaged. The movement around the 32 axis X4 can be restricted. Further, the teeth 32b and the tooth grooves 32c are formed in the same shape and at equal intervals, and the teeth 33d and the tooth grooves 33e are formed in the same shape and at equal intervals, respectively. The eccentric ring 32 can be rotated quantitatively by rotating the ring 32 and changing each tooth 32b engaged with each tooth groove 33e and changing each tooth 33d engaged with each tooth groove 32c. Further, when the eccentric ring 32 is rotated, if the eccentric ring 32 is separated from the adjustment lever 33 against the biasing force of the spring member 6, each tooth 32b is detached from each tooth groove 33e and each tooth 33d is each tooth groove. Since the eccentric ring 32 can be easily rotated with respect to the control shaft 31, the eccentric ring 32 is rotated with respect to the control shaft 31, and each tooth 32b is engaged with each tooth groove 33e. When the teeth 33d are engaged with the tooth grooves 32c, the eccentric ring 32 and the adjustment lever 33 are brought into close contact with each other by the urging force of the spring member 6, so that the eccentric ring 32 is firmly attached to the control shaft 31. Can be fixed.
<< Embodiment 2 of the Invention >>
FIG. 11 shows a variable valve mechanism 1 according to Embodiment 2 of the present invention. In the second embodiment, only the structure of the second pressing portion 21b is different from that of the first embodiment, and the others are the same as those of the first embodiment. Therefore, only the parts different from the first embodiment will be described below.

  In the second embodiment, a portion of the second pressing portion 21b of one control arm 21 that is in contact with the curved surface portion 11e of the swing arm 11 has a midway portion positioned below as viewed from the axial center X1 direction of the camshaft 2. It is curved.

  Then, although illustration of each lift curve of the valve 10 corresponding to one control arm 21 of Embodiment 2 is omitted, a line connecting the points of the maximum lift amount of each lift curve over the entire lift curve, A curve S2 indicated by a two-dot chain line in FIG. 6 is obtained. That is, the valve 10 corresponding to one control arm 21 tends to open earlier than the valve 10 corresponding to the other control arm 21.

Therefore, since the lift characteristics of the two valves 10 in the same cylinder can be made different from each other, it is possible to flexibly correspond to the engine specifications.
<< Embodiment 3 of the Invention >>
FIG. 12 shows a variable valve mechanism 1 according to Embodiment 3 of the present invention. In the third embodiment, only the structure around the control shaft 31 is different from that in the first embodiment, and the other parts are the same as those in the first embodiment. Therefore, only the parts different from the first embodiment will be described below.

  A pair of perfect circular rings 34 are externally fitted and fixed to the control shaft 31 of the third embodiment at positions corresponding to the respective rollers 12. 34a is formed as a recess.

  A C-shaped shim 7 (lift fine adjustment means) is detachably attached to the outer peripheral surface of the annular ring 34 on the swing arm 11 side.

  A pair of locking projections 7a that are locked to the respective locking recesses 34a are provided at both ends on the inner peripheral side of both ends of the C-shaped shim 7, and the C-shaped shim 7 is connected to the annular ring. 34, the outer peripheral surface comes into contact with the outer surface around the swing axis X2 of the swing arm 11 at a position where the outer peripheral surface protrudes outward from the annular ring 34. Note that the phantom line in FIG. 11 indicates the posture of the swing arm 11 when the C-shaped shim 7 is not attached to the annular ring 34.

  Therefore, by changing the thickness of the C-shaped shim 7, the position of the outer peripheral surface of the C-shaped shim 7 changes in the radial direction of the control shaft 31, and accordingly, the outer periphery of the swing arm 11 around the swing axis X2 is changed. Since the position of the side surface moves, the position of the swing axis X2 of the swing arm 11 can be easily changed.

  Further, when the C-shaped shim 7 is attached to the control shaft 31, the position of the C-shaped shim 7 does not shift with respect to the control shaft 31, and the attachment of the C-shaped shim 7 to the control shaft 31 can be stabilized. .

  In the first to third embodiments of the present invention, the variable valve mechanism 1 is applied to the intake valve 10. However, the variable valve mechanism 1 can also be applied to the exhaust valve 10.

  In the first to third embodiments of the present invention, the swing arm 11 indirectly presses the valve 10 via the rocker arm 41, but the valve 10 may be pressed directly without using the rocker arm 41. Good.

  In the first and second embodiments of the present invention, the teeth 32b of the eccentric ring 32 are defined as the engagement protrusions of the present invention, and the tooth grooves 33e of the annular ridge 33b are defined as the engagement recesses of the present invention. The 32 tooth grooves 32c may be defined as the engagement recesses of the present invention, and the teeth 33d of the annular protrusion 33b may be defined as the engagement protrusions of the present invention.

  In Embodiment 3 of the present invention, the locking projection 7 a is provided on the C-shaped shim 7, and the locking recess 34 a for locking the locking projection 7 a is provided on the annular ring 34. You may provide the latching recessed part 34a which the latching protrusion 7a latches the latching recessed part 34a to the C-shaped shim 7. FIG.

  The present invention is suitable for a variable valve mechanism that can change the lift amount and opening period of an intake / exhaust valve of an engine.

DESCRIPTION OF SYMBOLS 1 Variable valve mechanism 2 Cam shaft 6 Spring member (biasing means)
7 C-shaped shim 7a Locking projection 10 Valve 11 Swing arm 21 Control arm 21a Main body 21b Second pressing part 31 Control shaft 32 Eccentric ring (fine adjustment means)
32a Groove groove (marking part)
32b Teeth (engagement protrusion)
33 Adjustment lever 33b Annular protrusion 33c Projection 33e Tooth groove (engagement recess)
34a Locking recess

Claims (10)

Intake and exhaust valves;
A camshaft that rotates in synchronization with the crankshaft of the engine;
A control arm provided so as to be swingable around an axis extending in the same direction as the axis of the camshaft, and being pressed by the rotation of the camshaft and swinging;
The camshaft is provided so as to be swingable about an axis extending in the same direction as the axis of the camshaft. The control arm is pressed and swings by the swinging operation of the control arm, and the valve is directly or indirectly controlled by the swinging operation. A swing arm that presses against and lifts,
A lift adjusting means for adjusting a lift amount and an open period of the valve by changing a pressing position of the control arm with respect to the swing arm by changing a relative position of the control arm with respect to the swing arm;
A variable valve mechanism comprising: a lift fine adjusting means for finely adjusting a lift amount and an open period of the valve by moving a position of a swing axis of the swing arm. The variable valve mechanism according to claim 1,
The lift adjusting means includes a control shaft that rotates about an axis extending in the same direction as the axis of the camshaft, and is provided integrally with the control shaft so as to rotate outwardly, and protrudes radially outward of the control shaft. An adjustment lever having a protruding portion that pivotally supports the
The adjusting lever rotates together with the control shaft about the axis of the control shaft, so that the swing axis of the control arm is turned to the swing axis of the swing arm when viewed from the axial direction of the camshaft. A variable valve mechanism that moves in a direction in which the valve moves toward and away from the valve. In the variable valve mechanism according to claim 1 or 2,
A variable valve mechanism characterized in that a peripheral portion of a swing axis of the swing arm is arranged so as to be shifted in a direction of an axis of the camshaft with respect to a peripheral portion of the swing axis of the control arm. . In the variable valve mechanism according to any one of claims 1 to 3,
When the valve is closed, the swing axis of the control arm passes through the swing axis of the swing arm and the pressing position of the control arm with respect to the swing arm when viewed from the axial direction of the camshaft. A variable valve mechanism characterized by being located on or near a straight line. In the variable valve mechanism according to any one of claims 1 to 4,
A pair of the valves are juxtaposed in the axial direction of the camshaft in the same cylinder of the engine,
A pair of the swing arms are provided corresponding to the valves,
The control arm includes a main body portion disposed between the swing arms in the axial direction of the camshaft, and a pair of pressing portions that are provided integrally with the main body portion and press the swing arms. A variable valve mechanism characterized by that. The variable valve mechanism according to claim 5,
2. A variable valve mechanism according to claim 1, wherein the shapes of the pressing portions for pressing the swing arm of the control arms are different from each other. The variable valve mechanism according to any one of claims 2 to 6,
The lift fine adjustment means includes an eccentric ring that is externally fitted to the control shaft so as to be rotatable about the axis of the control shaft, and whose outer peripheral surface is in contact with an outer surface around the swing axis of the swing arm. A variable valve mechanism characterized by comprising: The variable valve mechanism according to claim 7,
The lift fine adjustment means further includes a biasing means for biasing the eccentric ring toward the adjustment lever in the axial direction of the control shaft,
The adjustment lever includes an annular ridge extending around the control shaft,
A plurality of engaging protrusions of the same shape are provided at equal intervals in the circumferential direction on either one of the end surface on the adjustment lever side of the eccentric ring and the side surface of the annular ridge portion, and on the other side Is provided with a plurality of engaging recesses of the same shape with which the engaging protrusions are detachably engaged with each other in the circumferential direction at equal intervals,
A variable valve mechanism characterized by changing the position of the eccentric ring in the circumferential direction relative to the control shaft by rotating the eccentric ring against the urging force of the urging means. The variable valve mechanism according to any one of claims 2 to 6,
The lift fine adjustment means is detachably attached to the outer peripheral surface of the control shaft on the swing arm side, and is attached to the outer peripheral surface of the control shaft at a position where the outer peripheral surface protrudes outward from the outer peripheral surface of the control shaft. A variable valve mechanism, wherein the swing arm is a C-shaped shim that contacts an outer surface around a swing axis. The variable valve mechanism according to claim 9,
A pair of locking projections are provided on either the inner circumferential side end of the C-shaped shim or the outer circumferential surface of the control shaft, and the other locking projections are engaged on the other. A variable valve mechanism having a pair of locking recesses to be stopped.

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