JP2016084778A - Variable valve operating device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable valve gear of an internal combustion engine which is reduced in size and can enhance the reliability of motion.SOLUTION: In a variable valve gear 2, when either of a first arm part 52 or a second arm part 53 moves to a direction in which the arm part separates from a guide groove 43 of a control shaft 55 in an oscillation direction accompanied by the oscillation of the control shaft 55, and also when the other of the first arm part 52 or the second arm part 53 moves to a direction in which the arm part approximates the guide groove 43 of the control shaft 55 in the oscillation direction, an insertion-direction tip part of a first changeover pin 52A and an insertion-direction tip part of a second changeover pin 53A are located at a side opposite to the guide groove 43 with respect to an external peripheral face 4A of a cam carrier 4 in a circumferential direction of the control shaft 55 immediately before the insertion-direction tip part of the first changeover pin 52A or the insertion-direction tip part of the second changeover pin 53A is inserted into the guide groove 43, and a first clearance D1 and a second clearance D2 are formed between the external peripheral face 4A of the cam carrier 4 and the variable valve gear.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a variable valve operating apparatus for an internal combustion engine that moves a cam carrier having a plurality of cams having different valve operating characteristics in the axial direction of a cam shaft.

  2. Description of the Related Art Conventionally, as a variable valve operating apparatus for an internal combustion engine, a variable valve operating valve that switches a cam for operating a valve by moving a cam carrier having a plurality of cams with different valve operating characteristics on the outer periphery in the axial direction of the cam shaft. An apparatus is known (see Patent Document 1).

  In the variable valve operating apparatus, a central groove, a first spiral groove, and a second spiral groove are formed in a cam carrier, and the first spiral groove and the second spiral groove are branched from the center groove. In addition, the variable valve operating apparatus includes an engagement member in which a first arm and a second arm are provided in a V shape, and the engagement member is rotated by an actuator so that the inside of the distal end portion of the first arm Either the first engaging portion formed on the inner side or the second engaging portion formed on the inner side of the tip of the second arm is inserted into the first spiral groove or the second spiral groove, and the cam carrier is moved in the axial direction. .

Japanese Patent No. 5117475

  However, in the conventional variable valve operating apparatus, both the first engaging portion and the second engaging portion are inserted into the first spiral groove and the second spiral groove at the same time due to variations in the drive timing of the actuator, etc. In addition, there is a possibility that the second engaging portion strongly interferes with the first spiral groove and the second spiral groove. When the first engaging portion and the second engaging portion strongly interfere with the first spiral groove and the second spiral groove, the reliability of the operation of the variable valve device is lowered.

  Further, in the conventional variable valve operating apparatus, the cam carrier is provided with the first spiral groove and the second spiral groove from the central groove, which is three grooves, and the first spiral groove and the second spiral groove are branched from the central groove. Therefore, the groove structure may be complicated. If the structure of the groove is complicated, the variable valve operating apparatus becomes large.

  The present invention has been made by paying attention to the above-described problems, and an object of the present invention is to provide a variable valve operating apparatus that can be downsized and can improve operation reliability.

  The present invention is provided with a cam shaft rotatably supported by a cylinder head and coaxial with the cam shaft, and rotates integrally with the cam shaft and moves in the axial direction of the cam shaft. And a cam carrier having a first cam and a second cam which are formed on the outer peripheral surface so as to have different operating characteristics of the valve. The cam carrier is disposed adjacent to each other, and the cam carrier is arranged in the axial direction of the cam shaft. In the variable valve operating apparatus for an internal combustion engine that switches the cam that moves the valve to operate the valve, the cam carrier operates the valve by the first cam and the second cam by operating the valve by the first cam. A single guide groove is formed on the outer peripheral surface of the cam carrier so as to go around the cam carrier, and the guide groove is formed on the cam carrier. The first switching cam for moving to the first position and the second switching cam for moving the cam carrier to the second position, having a pair of side walls facing each other, having a rotation center axis, A cam switching member having a first arm portion and a second arm portion which are arranged so that a control shaft swinging around a central axis extends in parallel with the cam shaft and faces the control shaft across the cam carrier. A first shaft that can be integrally rotated with the control shaft, can be inserted into the guide groove as the control shaft swings, and can contact the first switching cam. A first protrusion is provided, and a second protrusion that can be inserted into the guide groove along with the swing of the control shaft and that can contact the second switching cam is provided at the tip of the second arm. Provided with the swing of the control shaft, One of the second arm portions moves away from the guide groove in the swing direction of the control shaft, and the other of the first arm portion or the second arm portion moves in the swing direction of the control shaft. When moving in the direction approaching the guide groove, the insertion direction of the first protrusion immediately before the insertion direction tip of the first protrusion or the insertion direction tip of the second protrusion is inserted into the guide groove. A distal end portion and a distal end portion in the insertion direction of the second projecting portion are located on the opposite side of the guide groove with respect to the outer peripheral surface of the cam carrier in the circumferential direction of the control shaft, and the outer peripheral surface of the cam carrier It is comprised from what forms a clearance gap between.

  As described above, according to the present invention, the first switching cam and the second switching cam have a pair of side walls, the single guide groove that does not have a spiral shape, and the first that can come into contact with the first switching cam. Since a mechanism for switching between the first cam and the second cam can be configured by the protrusion and the second protrusion that can come into contact with the second switching cam, each of the first protrusion and the second protrusion is complicated. There is no need to form a guide groove that branches into a guide groove or a guide groove that is provided individually. For this reason, the mechanism which switches a cam can be simplified.

  Thereby, since the occupied space of the guide groove in the cam carrier can be reduced as compared with the conventional structure, the overall length of the cam carrier in the axial direction can be reduced, and the variable valve operating apparatus can be downsized.

  In addition, immediately before one of the first protrusion or the second protrusion is inserted into the guide groove, the distal end in the insertion direction of the first protrusion and the distal end in the insertion direction of the second protrusion are in the circumferential direction of the control shaft. In order to form a gap between the cam carrier outer peripheral surface and the cam carrier outer peripheral surface, the first protrusion and the second protrusion are located in the cam carrier guide groove. Can be prevented from contacting the pair of side walls of the guide groove.

  Thereby, it is prevented that the first protrusion and the second protrusion are simultaneously inserted into the pair of side walls of the guide groove and strongly interfere with each other, and the reliability of the variable valve apparatus can be improved.

  As a result, it is possible to provide a variable valve operating apparatus that can be downsized and improve the operation reliability.

FIG. 1 is a view showing a cylinder head provided with a variable valve operating apparatus for an internal combustion engine according to an embodiment of the present invention, and is a cross-sectional view of the cylinder head cut in the longitudinal direction of the vehicle. FIG. 2 is an exploded perspective view of the variable valve operating apparatus for the internal combustion engine according to the embodiment of the present invention. FIG. 3 is a perspective view showing a cam carrier in the variable valve operating apparatus for an internal combustion engine according to the embodiment of the present invention. FIG. 4 is a bottom view showing a state in which the cam carrier is switched to the first position in the variable valve operating apparatus for the internal combustion engine according to the embodiment of the present invention. FIG. 5 is a cross-sectional view taken in the direction of arrows II in FIG. FIG. 6 is a top view showing a state in which the cam carrier is switched to the first position in the variable valve operating apparatus for the internal combustion engine according to the embodiment of the present invention. FIG. 7 is a cross-sectional view taken along the line II-II in FIG. FIG. 8 is a top view showing a state in which the cam switching member is rotating in the variable valve operating apparatus for the internal combustion engine according to the embodiment of the present invention. 9 is a cross-sectional view taken along the line II-II in FIG. FIG. 10 is a top view showing a state when the cam switching member is completely rotated in the variable valve operating apparatus for the internal combustion engine according to the embodiment of the present invention. 11 is a cross-sectional view taken along the line II-II in FIG. FIG. 12 is a top view showing a state where the cam carrier is switched to the second position in the variable valve operating apparatus for the internal combustion engine according to the embodiment of the present invention. 13 is a cross-sectional view taken along the line II-II in FIG.

  Embodiments of a variable valve operating apparatus for an internal combustion engine according to the present invention will be described below with reference to the drawings. FIGS. 1-13 is a figure which shows the variable valve operating apparatus of the internal combustion engine of embodiment which concerns on this invention.

First, the configuration will be described.
(Schematic configuration of variable valve operating device)
As shown in FIG. 1, the variable valve gear 2 of the internal combustion engine 10 is built in the cylinder head 1 and the head cover 1A. The cylinder head 1 is attached to an upper portion of a cylinder block (not shown) constituting the internal combustion engine 10, and a head cover 1 </ b> A is attached to the upper portion of the cylinder head 1.

  As shown in FIGS. 1 to 3, the variable valve gear 2 includes a cam shaft 3, a cam carrier 4, and a cam switching mechanism 5 installed above the cam carrier 4. 2 performs cam switching in order to change the lift state of the intake valve 13.

  The cylinder head 1 includes a camshaft 30 on the exhaust valve side, an exhaust cam 40, an exhaust valve 39, and the like. Here, the variable valve gear 2 is provided on the camshaft 3 on the intake side. The intake valve 13 constitutes the valve of the present invention.

(Rocker arm)
As shown in FIGS. 1 and 2, the variable valve apparatus 2 of the present embodiment uses a rocker arm 11 of a type that swings with the rotation of the cam carrier 4. The rocker arm 11 has a recess formed on the lower surface of the arm base end portion 11 </ b> C, and the rocker arm 11 is installed on the pivot 12 </ b> A of the hydraulic lash adjuster (HLA) 12. In the center of the rocker arm 11, a circular pressed roller 11A as a roller is supported by a pin 11B.

  The pressed roller 11 </ b> A protrudes from the upper surface of the rocker arm 11, and the pressed roller 11 </ b> A contacts either the high speed cam 41 or the low speed cam 42 of the cam carrier 4. Therefore, the rocker arm 11 and the pressed roller 11 </ b> A are arranged between the cam carrier 4 and the intake valve 13 and contribute to the operation of the intake valve 13. Here, the high speed cam 41 constitutes the first cam of the present invention, and the low speed cam 42 constitutes the second cam of the present invention.

  The lower surface of the arm tip 11D on the other end side of the rocker arm 11 is in contact with the upper end of the intake valve 13. The intake valve 13 is provided so as to be able to advance and retract in the axial direction with respect to the cylinder head 1. The intake valve 13 is urged by a valve spring 14 in a direction to close the intake port 15 and the combustion chamber 16. (The intake valve is closed).

  When the rocker arm 11 is pushed by the cam carrier 4, the intake valve 13 is pushed down (lifted) against the urging force of the valve spring 14, and the intake port 15 and the combustion chamber 16 are opened (intake valve open state). ).

(Cam shaft)
In FIGS. 1 and 2, the cam shaft 3 is rotatably supported by a bearing portion (not shown) serving as a bearing portion installed on the upper portion of the cylinder head 1 and a cam housing 71. A cam sprocket (not shown) is provided at one end of the cam shaft 3, and a timing chain (not shown) is wound around the cam sprocket.

  The timing chain is wound around a cranks plot (not shown) of a crankshaft (not shown), and the timing chain transmits the rotation of the crankshaft to the camshaft 3. The rotational speed of the camshaft 3 is set to be 1/2 of the rotational speed of the crankshaft.

  In the variable valve operating apparatus 2 of the present embodiment, the camshaft 3 extends along the front-rear direction of the internal combustion engine 10 having the cylinder head 1 that constitutes a part of the internal combustion engine 10 (front-rear direction on the paper surface of FIG. 1). It is installed as follows.

  The cam housing 71 is covered with the head cover 1 </ b> A and is built in the cylinder head 1.

  The intake valves 13 are provided for each combustion chamber 16 as a set of two. The internal combustion engine 10 of the present embodiment is an in-line four-cylinder engine, and eight intake valves 13 are provided in four sets.

  Spline external teeth 31 having a predetermined width dimension in the axial direction are formed around the outer peripheral surface of the predetermined region in the length direction of the cam shaft 3.

  As shown in FIG. 5, the positioning mechanism 32 is provided in the area | region of the axial direction adjacent to the area | region in which the spline external tooth 31 in the cam shaft 3 was formed.

  The positioning mechanism 32 includes a storage recess 33 formed to be recessed in the radial direction with respect to the cam shaft 3 formed on the outer peripheral surface of the cam shaft 3, a spring 34 stored in the storage recess 33, and a storage A ball 35 housed in the recess 33 and installed so as to be urged radially outward of the camshaft 3 by the spring 34, a first positioning groove 46 formed on the inner peripheral surface of the cam carrier 4, And a second positioning groove 47.

  The ball 35 is fitted into either the first positioning groove 46 or the second positioning groove 47 provided in the cam carrier 4.

(Cam carrier)
2, 3, and 4, the cam shaft 4 is provided with a cam carrier 4. The cam carrier 4 is formed in a cylindrical shape so as to surround the cam shaft 3, and spline inner teeth 45 that mesh with the spline outer teeth 31 of the cam shaft 3 are formed on the inner peripheral surface of the cam carrier 4. For this reason, the cam carrier 4 rotates integrally with the cam shaft 3 and is movable in the axial direction with respect to the cam shaft 3.

  A high-speed cam 41 and a low-speed cam 42 having different valve operating characteristics are integrally provided on the outer peripheral surface of the cam carrier 4 side by side in the axial direction. Note that a single (two) unitary structure of the high-speed cam 41 and the low-speed cam 42 is provided on one cam carrier 4 at a predetermined interval.

  When a pair of high-speed cams 41 is selected, each high-speed cam 41 comes into contact with the pressed roller 11A, and when a pair of low-speed cams 42 is selected, each low-speed cam 42 is pressed against the pressed roller 11A. Contact with.

  That is, the interval between the high-speed cams 41, the interval between the low-speed cams 42, and the interval between the intake valves 13 are set to be the same. The cam carrier 4 has a first position P1 (see FIG. 4) where the high-speed cam 41 operates the intake valve 13 on the camshaft 3, and a second position P2 where the low-speed cam 42 operates the intake valve 13 (see FIG. 4). 4). In the figure, the first position P1 and the second position P2 of the cam carrier 4 are represented by the positions of the second stopper portions 64B.

  The high-speed cam 41 includes a base circle portion 41A that serves as a foundation, and a nose portion 41B that protrudes radially outward from the base circle portion 41A. The low-speed cam 42 has a base circle portion 42A having the same radius as the base circle portion 41A of the high-speed cam 41 serving as a base, and a radial direction outward from the base circle portion 42A in the radial direction from the nose portion 41B of the high-speed cam 41. And a nose portion 42B formed with a small projecting dimension.

  When the cam carrier 4 rotates, the base circle portions 41A and 42A do not push down the pressed roller 11A, that is, do not push down the intake valve 13. The nose portions 41B and 42B push down the pressed roller 11A, that is, lift the intake valve 13.

  That is, the nose portion 41B of the high speed cam 41 of this embodiment is formed larger than the nose portion 42B of the low speed cam 42, and the protruding dimension of the nose portion 41B of the high speed cam 41 is the same as that of the nose portion 42B of the low speed cam 42. It is larger than the protruding dimension. The nose portion 41B and the nose portion 42B constitute the cam nose portion of the present invention.

  Thus, the high-speed cam 41 and the low-speed cam 42 are respectively composed of a large lift cam having a relatively large lift amount and a small lift cam having a relatively small lift amount. Therefore, when the intake valve 13 is operated by the high speed cam 41, the lift amount of the intake valve 13 can be made larger than when the intake valve 13 is operated by the low speed cam 42, and more combustion chamber 16 is used. Intake air can be inhaled. Moreover, the opening time can be extended by making the operating angle of the high-speed cam 41 larger than that of the low-speed cam 42.

  Therefore, the output of the internal combustion engine 10 is increased at the first position P1 at which the intake valve 13 is operated by the high speed cam 41 than at the second position P2 at which the intake valve 13 is operated by the low speed cam 42. The variable valve device 2 moves the cam carrier 4 in accordance with the operating condition, thereby selecting either the high-speed cam 41 or the low-speed cam 42 as the cam that contacts the pressed roller 11A, and the lift state of the intake valve 13 To change.

  The high-speed cam 41 and the low-speed cam 42 are installed adjacent to each other along the axial direction, and the base circle portions 41A and 42A of the high-speed cam 41 and the low-speed cam 42 are continuous surfaces formed flush with each other in the axial direction. It has become.

  Further, the nose portions 41B and 42B of the high-speed cam 41 and the low-speed cam 42 are installed in a direction having substantially the same phase. The high-speed cam 41 and the low-speed cam 42 define the lift timing of the intake valve 13 according to the installation state with respect to the cam shaft 3.

  As shown in FIG. 5, the first positioning groove 46 and the second positioning groove 47 go around the area adjacent to the area where the spline inner teeth 45 (see FIG. 2) are formed on the inner peripheral surface of the cam carrier 4. It is formed to do.

  The first positioning groove 46 and the second positioning groove 47 are configured such that the ball 35 of the positioning mechanism 32 provided on the camshaft 3 side is fitted into one according to the movement of the cam carrier 4. The cam carrier 4 is positioned at the first position P1 or the second position P2.

  In the low speed cam 42, the radius of the nose portion 42B is formed to be the same as that of the base circle portion 42A. Thus, when the cam carrier 4 is switched to the second position P2, the intake valve 13 does not operate and the cylinder is deactivated.

  As shown in FIGS. 2, 3, and 4, a single guide groove 43 is formed on the outer peripheral surface of the cam carrier 4 so as to continuously go around the cam carrier 4. In the guide groove 43, one of the pair of side walls facing each other is a first switching cam 43A that moves the cam carrier 4 to the first position P1, and the other of the pair of side walls is The second switching cam 43B is moved to the second position P2.

  Each of the first switching cam 43A and the second switching cam 43B includes a minimum cam peak portion 43C in which the axial width of the cam shaft 3 is minimized, and the minimum cam peak portion 43C is a flat surface.

  Each of the first switching cam 43A and the second switching cam 43B includes a maximum cam crest 43D having a maximum axial width of the cam shaft 3, a minimum cam crest 43C, and a maximum cam crest 43D. And an inclined cam crest 43E that communicates with each other.

  Further, the minimum cam crest 43C, the maximum cam crest 43D and the inclined cam crest 43E of the first switching cam 43A, and the minimum cam crest 43C, the maximum cam crest 43D and the inclined cam crest 43E of the second switching cam 43B. Is shifted by, for example, 180 ° in the circumferential direction of the cam shaft 3. The deviation angle is not limited to this. Thus, the guide groove 43 of the present embodiment is configured such that the width changes in the axial direction of the cam shaft 3.

(Cam switching mechanism)
In FIGS. 1, 2, 4, and 5, the cam switching mechanism 5 includes a cam switching member 51, and the cam switching member 51 has a first arm portion 52 and a second arm facing each other with the cam carrier 4 interposed therebetween. It has an arm part 53.

  The cam switching member 51 is formed in a V shape when viewed in the axial direction of the cam shaft 3, and the base ends 54 of the first arm portion 52 and the second arm portion 53 constituting the cam switching member 51 are continuously formed. Yes.

  Base ends 54 of the first arm portion 52 and the second arm portion 53 are attached to a control shaft 55. The control shaft 55 has a rotation center shaft 55A extending in parallel with the rotation center shaft 3A (see FIG. 2) of the cam shaft 3, and swings the cam switching member 51 around the rotation center shaft 55A. The control shaft 55 is rotatably supported by a control shaft support hole 71 </ b> A formed in the upper part of the cam housing 71.

  A spacer 74 is mounted on the outer periphery of the control shaft 55, and this spacer 74 is provided between the cam switching member 51 and the cam housing 71. The spacer 74 holds the position of the cam switching member 51 in the axial direction of the cam shaft 3.

  An actuator 61 is attached to the head cover 1 </ b> A, and this actuator 61 is arranged to face the first arm portion 52 of the cam switching member 51.

  The actuator 61 has a plunger 61 </ b> A that reciprocates, and this plunger 61 </ b> A is connected to a connecting portion 52 </ b> C formed outside the tip portion of the first arm portion 52. The actuator 61 swings the cam switching member 51 in one direction and the other direction via the first arm portion 52 by the advancement and retraction of the plunger 61A. When the cam switching member 51 swings, the control shaft 55 swings integrally.

  In FIG. 1, a housing 62 is attached to the upper portion of the head cover 1 </ b> A, and the housing 62 extends from one end portion of the cam shaft 3 toward the other end portion. An oil separator chamber 63 is formed inside the housing 62, and the oil separator chamber 63 is configured by a space surrounded by the inner peripheral surface of the housing 62 and the upper surface of the head cover 1A.

  In the oil separator chamber 63, for example, collision walls (not shown) are alternately arranged from one end portion of the cam shaft 3 toward the other end portion. The blow-by gas introduced into the oil separator chamber 63 from the head cover 1A collides with the collision wall, whereby the oil contained in the blow-by gas is separated.

  The blow-by gas from which the oil has been separated is introduced from an oil separator chamber 63 into an intake pipe (not shown) through a blow-by gas discharge pipe (not shown), then introduced into the combustion chamber 16 from the intake pipe and burned in the combustion chamber 16.

  Here, the blow-by gas is an unburned mixture or combustion gas leaked from the combustion chamber 16 into a crankcase (not shown) of the internal combustion engine, and the blow-by gas passes through the blow-by gas introduction pipe (not shown) from the crankcase to the oil separator chamber. 63.

  The upper wall of the head cover 1A bulges toward the oil separator chamber 63, and the control shaft 55 is installed closer to the camshaft 3 than the bulged portion. As a result, the control shaft 55 is doubly covered by the head cover 1 </ b> A and the housing 62.

  1, 2, 4, and 5, a first switching pin 52 </ b> A is provided on the inner side of the distal end portion of the first arm portion 52 that faces the cam carrier 4, and the first switching pin 52 </ b> A is When the cam switching member 51 swings in one direction as the control shaft 55 swings, it can be inserted into the guide groove 43 and can contact the first switching cam 43A.

  On the other hand, a second switching pin 53A is provided on the inner side of the distal end portion of the second arm portion 53 facing the cam carrier 4, and this second switching pin 53A switches the cam when the control shaft 55 swings. When the member 51 swings in the other direction, it can be inserted into the guide groove 43 and can be brought into contact with the second switching cam 43B.

  The second switching pin 53A is separated from the first switching pin 52A in the axial direction of the cam shaft 3.

  The distance between the central axis of the first switching pin 52A and the central axis of the second switching pin 53A in the axial direction of the cam shaft 3 is the distance between the central axis in the width direction of the high speed cam 41 and the central axis in the width direction of the low speed cam 42. The same.

  That is, the first switching pin 52A and the second switching pin 53A are offset in the axial direction of the cam shaft 3 by an amount equal to the cam pitch t between the high speed cam 41 and the low speed cam 42.

  A first stopper portion 64 </ b> A and a second stopper portion 64 </ b> B are provided on the outer peripheral portion of the cam carrier 4. The first stopper portion 64A and the second stopper portion 64B are provided outward in the axial direction of the cam carrier 4 with respect to the first switching cam 43A and the second switching cam 43B. The first stopper portion 64A and the second stopper portion 64B are formed in a flange shape so as to expand outward in the radial direction of the cam carrier 4.

  Specifically, the first stopper portion 64A is located on the side opposite to the first switching cam 43A with respect to the second switching cam 43B and rises from the outer peripheral surface 4A of the cam carrier 4 toward the radially outer side.

  The second stopper portion 64B is located on the opposite side of the first switching cam 43A from the second switching cam 43B and rises radially outward from the outer peripheral surface 4A of the cam carrier 4. 64 A of 1st stopper parts and the 2nd stopper part 64B comprise the 1st control part and 2nd control part in this invention, respectively.

  The first stopper portion 64A and the second stopper portion 64B are formed in the same shape, and the heights of the radially outer ends of the first stopper portion 64A and the second stopper portion 64B are the same.

  Here, the first stopper portion 64A and the second stopper portion 64B may be integrally formed with the cam carrier 4 by casting or the like. In this way, the productivity of the cam carrier 4 can be improved. The first stopper portion 64 </ b> A and the second stopper portion 64 </ b> B may be formed separately from the cam carrier 4 and retrofitted to the cam carrier 4.

  64 A of 1st stopper parts and the 2nd stopper part 64B contact the 1st arm part 52 or the 2nd arm part 53, and the cam carrier 4 moves to the axial direction of the cam shaft 3 exceeding a predetermined position too much. It has a function to regulate this.

  Specifically, the side surface in the width direction of the first arm portion 52 includes a first contact portion 52B that faces the first stopper portion 64A and contacts the first stopper portion 64A. The first contact portion 52B protrudes from the side surface in the width direction of the first arm portion 52 facing the first stopper portion 64A toward the first stopper portion 64A, and the tip end portion of the first arm portion 52 is formed wide. .

  Further, the second arm portion 53 has a second contact portion 53B that faces the second stopper portion 64B and contacts the second stopper portion 64B. The second contact portion 53B protrudes from the side surface in the width direction of the second arm portion 53 facing the first stopper portion 64A toward the second stopper portion 64B, and the tip end portion of the second arm portion 53 is formed wide. .

  In other words, the second contact portion 53B expands from the first switching pin 52A toward the first stopper portion 64A in the axial direction of the cam carrier 4 on the first arm portion 52, and the second contact portion 53B extends to the cam carrier. 4 is enlarged from the second switching pin 53A toward the second stopper portion 64B in the axial direction of 4. As shown in FIG. The first contact portion 52B and the second contact portion 53B constitute the first enlarged portion and the second enlarged portion in the present invention, respectively.

  When the cam switching member 51 swings in one direction integrally with the control shaft 55, the first switching pin 52A of the first arm portion 52 is inserted into the guide groove 43, and the second switching pin of the second arm portion 53 is inserted. 53A is detached from the guide groove 43.

  Further, when the cam switching member 51 swings in the other direction integrally with the control shaft 55, the second switching pin 53A of the second arm portion 53 is inserted into the guide groove 43, and the first arm portion 52 of the first arm portion 52 is inserted. The switching pin 52A is detached from the guide groove 43.

  A first contact portion 52B is provided on the first arm portion 52 so as to overlap the first stopper portion 64A in the axial direction of the camshaft 3 when the first switching pin 52A is inserted into the guide groove 43.

  Further, since the heights of the radially outer ends of the first stopper portion 64A and the second stopper portion 64B are the same, when the second switching pin 53A is inserted into the guide groove 43, in the axial direction of the cam shaft 3 A second contact portion 53B is provided on the second arm portion 53 so as to overlap the second stopper portion 64B. The first switching pin 52A constitutes the first protrusion of the present invention, and the second switching pin 53A constitutes the second protrusion of the present invention.

  In FIG. 4, the cam carrier 4 moves from the first position P <b> 1 where the valve is operated by the high speed cam 41 to the second position P <b> 2 where the valve is operated by the low speed cam 42. The contact portion 53B is in contact with the second stopper portion 64B.

  In the present embodiment, in the state shown in FIG. 4, the variable valve apparatus 2 sets the first distance c from the second stopper portion 64B to the second switching cam 43B in the axial direction of the cam shaft 3 from the second stopper portion 64B. It is set to be larger than the second distance d to the second switching pin 53A.

  Further, in the state shown in FIG. 4, the variable valve apparatus 2 sets the third distance a obtained by subtracting the second distance d from the first distance c between the pressed roller 11 </ b> A and the maximum peak portion of the high-speed cam 41. It is set to be smaller than the gap dimension b.

  Next, the operation will be described. Hereinafter, based on FIGS. 6-13, the switching operation to the high speed cam 41 and the low speed cam 42 in the variable valve apparatus 2 which concerns on this embodiment is demonstrated. 6 to 13, the direction of the arrow R <b> 1 is the rotation direction of the cam shaft 3.

(Operation with high-speed cam 41)
6 and 7, when the high speed cam 41 is operated, the cam switching member 51 is swung in one direction integrally with the control shaft 55 by the advance of the plunger 61A of the actuator 61 (see FIG. 2). Thus, the first switching pin 52 </ b> A of the first arm portion 52 is inserted into the guide groove 43.

  The first switching cam 43A of the cam carrier 4 includes an inclined cam peak portion 43E that communicates between the maximum cam peak portion 43D and the minimum cam peak portion 43C and swells in the axial direction of the cam shaft 3. Thus, when the first switching pin 52A is inserted into the guide groove 43 when the cam carrier 4 is in the second position, the first switching pin 52A comes into contact with the minimum cam crest 43C of the first switching cam 43A. Then, a force on the right in the axial direction acts on the cam carrier 4 in contact with the inclined cam crest 43E.

  For this reason, the cam carrier 4 moves to the first position P1 when the first switching cam 43A is pressed by the first switching pin 52A. At this time, the movement of the cam carrier 4 is completed in a section in which the base circle portion 42A of the low-speed cam 42 and the base circle portion 41A of the high-speed cam 41 are in contact with the pressed roller 11A of the rocker arm 11.

  Thus, by moving the first switching pin 52A in the axial direction of the cam shaft 3, the first switching pin 52A moves from the minimum cam peak 43C of the first switching cam 43A to the maximum cam peak 43D through the inclined cam peak 43E. To move the cam carrier 4 to the first position P1.

  Further, when the cam carrier 4 moves to the first position P1 with respect to the cam shaft 3 in this way, the ball 35 on the cam shaft 3 side is disengaged from the second positioning groove 47 shown in FIG. It will be in the state which moved and fitted to the groove | channel 46 for use. As a result, the cam carrier 4 is fixed to the first position P1 where the high speed cam 41 is selected with respect to the cam shaft 3.

  Further, when the high speed cam 41 is selected and the cam carrier 4 is in the first position P1, the first switching is performed until the switching to the low speed cam 42 is performed as shown in FIGS. As shown in FIGS. 6 and 7, the pin 52 </ b> A is opposed to the maximum cam crest 43 </ b> D of the guide groove 43 so that the position of the high speed cam 41 is maintained, and the high speed cam 41 continues to operate.

  As shown in FIG. 6, when the cam carrier 4 moves to the first position P1 with respect to the cam shaft 3, the second stopper portion 64B moves by an amount equal to the cam pitch t. The first stopper portion 64A also moves together with the second stopper portion 64B and contacts the first contact portion 52B of the first arm portion 52. As a result, the cam carrier 4 is restricted from moving too much in the axial direction of the camshaft 3 beyond the first position P1 due to inertial force.

(Operation with low speed cam 42)
On the other hand, during operation by the low-speed cam 42, the cam switching member 51 is swung in the other direction integrally with the control shaft 55 by the retraction of the plunger 61 </ b> A of the actuator 61, as shown in FIGS. 8 and 9.

  Accordingly, as the control shaft 55 swings, the first arm portion 52 moves away from the guide groove 43 in the swing direction of the control shaft 55 and the second arm portion 53 swings the control shaft 55. In the direction of approaching the guide groove 43 in the direction, and the leading end of the second switching pin 53 </ b> A of the second arm portion 53 is inserted into the guide groove 43.

  In the present embodiment, as shown in FIG. 9, immediately before the distal end portion of the second switching pin 53A is inserted into the guide groove 43, the distal end portion of the first switching pin 52A and the second switching pin 53A are inserted. The distal end in the insertion direction is located on the opposite side of the guide groove 43 with respect to the outer peripheral surface 4A of the cam carrier 4 in the circumferential direction of the control shaft 55, and between the outer peripheral surface 4A of the cam carrier 4 and the first gap D1. Each of the second gaps D2 is formed.

  In the present embodiment, when switching from the high speed cam 41 to the low speed cam 42 is performed, when the control shaft 55 is viewed from the axial direction, the center point 55P of the control shaft 55 and the center point 3P of the cam shaft 3 A first angle θ1 formed by a straight line L3 passing through the first arm portion 52 and a first imaginary line L1 extending along the first arm portion 52 and intersecting the straight line L3, and extending along the straight line L3 and the second arm portion 53. The second angle θ2 formed by the second virtual line L2 intersecting with the straight line L3 passes through the same state. Here, the center point 55P of the control shaft 55 and the center point 3P of the cam shaft 3 are respectively a point on the rotation center axis 55A of the control shaft 55 and a rotation center axis 3A of the cam shaft 3 in the II-II section of FIG. This is the top point.

  In this state, a first gap D1 is formed between the insertion direction front end portion of the first switching pin 52A and the outer peripheral surface 4A of the cam carrier 4, and the insertion direction front end portion of the second switching pin 53A and the cam. A second gap D2 is formed between the outer peripheral surface 4A of the carrier 4 and the first gap D1 and the second gap D2 are equal.

  Then, as shown in FIGS. 10 and 11, the plunger 61 </ b> A of the actuator 61 is further retracted to further swing the cam switching member 51 in the other direction integrally with the control shaft 55, so that the second arm portion 53. The second switching pin 53 </ b> A is inserted into the guide groove 43, and the first switching pin 52 </ b> A of the first arm portion 52 is detached from the guide groove 43.

  The second switching cam 43B of the cam carrier 4 includes an inclined cam peak portion 43E that communicates between the maximum cam peak portion 43D and the minimum cam peak portion 43C and swells in the axial direction of the cam shaft 3. Accordingly, when the second switching pin 53A is inserted into the guide groove 43 when the cam carrier 4 is at the first position P1, the second switching pin 53A is moved to the first switching cam 43A as the cam carrier 4 rotates. After contacting the minimum cam crest 43C, the cam carrier 4 is subjected to an axial force by contacting the inclined cam crest 43E.

  Therefore, as shown in FIGS. 12 and 13, the cam carrier 4 moves to the second position P2 when the second switching cam 43B is pressed by the second switching pin 53A. At this time, the movement of the cam carrier 4 is completed in a section in which the base circle portion 42A of the low-speed cam 42 and the base circle portion 41A of the high-speed cam 41 are in contact with the pressed roller 11A of the rocker arm 11.

  In this way, by moving the second switching pin 53A in the axial direction of the cam shaft 3, the second switching pin 53A moves from the minimum cam peak 43C of the second switching cam 43B to the maximum cam peak 43D through the inclined cam peak 43E. To move the cam carrier 4 to the second position P2.

  Further, when the cam carrier 4 moves to the second position P2 with respect to the cam shaft 3 in this way, the ball 35 on the cam shaft 3 side is disengaged from the first positioning groove 46 shown in FIG. It moves into the groove 47 and is in a fitted state. As a result, the cam carrier 4 is fixed to the second position P2 where the low speed cam 42 is selected with respect to the cam shaft 3.

  In addition, when the low speed cam 42 is selected and the cam carrier 4 is in the second position P2, the second switching pin 53A has the maximum guide groove 43 until the switching to the high speed cam 41 is performed. The position of the low-speed cam 42 is maintained facing the cam crest 43D, and the low-speed cam 42 continues to operate.

  As shown in FIG. 4, when the cam carrier 4 moves to the second position P2 with respect to the cam shaft 3, the second stopper portion 64B comes into contact with the second contact portion 53B of the second arm portion 53. The carrier 4 is restricted from moving too much in the axial direction of the camshaft 3 beyond the second position P2 due to inertial force.

  Thus, during operation by the high-speed cam 41, the first stopper portion 64A comes into contact with the first contact portion 52B of the first arm portion 52, so that the cam carrier 4 is further moved from the first position P1 to the cam shaft 3 by the inertial force. The movement in the axial direction is restricted.

  Further, when the low speed cam 42 is operated, the second stopper portion 64B comes into contact with the second contact portion 53B of the second arm portion 53, so that the cam carrier 4 is further moved from the second position P2 to the axis of the camshaft 3 by inertial force. Movement in the direction is restricted.

  As described above, according to the variable valve apparatus 2 of the embodiment, as the control shaft 55 swings, one of the first arm portion 52 or the second arm portion 53 moves in the swing direction of the control shaft 55. When moving in the direction away from the guide groove 43 and the other of the first arm part 52 or the second arm part 53 moves in the direction of approaching the guide groove 43 in the swing direction of the control shaft 55, the first switching pin 52A Immediately before the insertion direction tip or the insertion direction tip of the second switching pin 53A is inserted into the guide groove 43, the insertion direction tip of the first switching pin 52A and the insertion direction tip of the second switching pin 53A are controlled. In the circumferential direction of the shaft 55, the first gap D <b> 1 and the second gap D <b> 2 are located between the outer circumferential surface 4 </ b> A of the cam carrier 4 and the outer circumferential surface 4 </ b> A of the cam carrier 4. Forming.

  As a result, the mechanism for switching between the high-speed cam 41 and the low-speed cam 42 has a pair of side walls composed of the first switching cam 43A and the second switching cam 43B, a single guide groove 43 that does not have a spiral shape, The first switching pin 52A that can come into contact with the first switching cam 43A and the second switching pin 53A that can come into contact with the second switching cam 43B can be used.

  Further, since the guide groove 43 does not need to be complicatedly branched for the first switching pin 52A and the second switching pin 53A or provided individually, the mechanism itself for switching the cam can be simplified.

  Thereby, since the occupied space of the guide groove 43 in the cam carrier 4 can be reduced as compared with the conventional structure, the overall length of the cam carrier 4 in the axial direction can be reduced, and the variable valve apparatus 2 can be reduced in size. Here, in the conventional variable valve operating apparatus, the guide groove is formed in a spiral shape, and a plurality of sub guide grooves branched from the main main guide groove are formed. Since it was necessary to provide a lamp (island) between the two, the overall length of the cam carrier in the axial direction was increased.

  Further, immediately before one of the first switching pin 52A or the second switching pin 53A is inserted into the guide groove 43, the distal end portion in the insertion direction of the first switching pin 52A and the distal end portion in the insertion direction of the second switching pin 53A are A first gap D <b> 1 and a second gap D <b> 2 are formed between the outer circumferential surface 4 </ b> A of the cam carrier 4 and the outer circumferential surface 4 </ b> A of the cam carrier 4. Therefore, it is possible to prevent the first switching pin 52A and the second switching pin 53A from being simultaneously inserted into the guide groove 43 of the cam carrier 4 and coming into contact with the pair of side walls of the guide groove 43.

  For this reason, it is prevented that the first switching pin 52A and the second switching pin 53A are simultaneously inserted into the guide groove 43 and strongly interfere with the pair of side walls, and the reliability of the variable valve apparatus 2 can be improved.

  As a result, it is possible to provide a variable valve operating apparatus that can be downsized and improve the operation reliability.

  Further, according to the variable valve apparatus 2 of the embodiment, when the control shaft 55 is viewed from the axial direction, the straight line L3 passing through the center point 55P of the control shaft 55 and the center point 3P of the cam shaft, and the first arm A first imaginary line θ1 formed by the first imaginary line L1 extending along the part 52 and intersecting the straight line L3, a second imaginary line extending along the second arm part 53 and intersecting the straight line L3. When the second angle θ2 formed by the line L2 is equal, a first gap D1 is formed between the distal end portion of the first switching pin 52A in the insertion direction and the outer peripheral surface 4A of the cam carrier 4, and the second switching is performed. A second gap D2 was formed between the distal end portion of the pin 53A in the insertion direction and the outer peripheral surface 4A of the cam carrier 4, and the first gap D1 and the second gap D2 were set to be equal.

  Thereby, even if the drive timing of the control shaft 55 by the actuator 61 varies, the first switching pin 52A of the first arm portion 52 and the second switching pin 53A of the second arm portion 53 simultaneously enter the guide groove 43. Insertion can be prevented.

  Accordingly, the first switching pin 52A and the second switching pin 53A can be inserted into and removed from the guide groove 43 so that the first switching pin 52A and the second switching pin 53A pass each other outside the guide groove 43. Therefore, the first switching pin 52A and the second switching pin 53A can be prevented from simultaneously strongly interfering with the side wall of the guide groove 43, and the reliability of the variable valve gear 2 can be reliably increased.

  Further, according to the variable valve operating apparatus 2 of the embodiment, the cam carrier 4 is positioned on the opposite side of the first switching cam 43A with respect to the second switching cam 43B and is radially outward from the outer peripheral surface 4A of the cam carrier 4. The first stopper portion 64A that rises toward the first position, and the second stopper portion that is located on the opposite side of the second switching cam 43B with respect to the first switching cam 43A and rises radially outward from the outer peripheral surface 4A of the cam carrier 4 64B.

  In addition to this, the variable valve apparatus 2 forms, in the first arm portion 52, a first contact portion 52B that expands from the first switching pin 52A toward the first stopper portion 64A in the axial direction of the cam carrier 4, The second arm portion 53 is formed with a second contact portion 53B that expands from the second switching pin 53A toward the second stopper portion 64B in the axial direction of the cam carrier 4, and the high-speed cam 41 and the low-speed cam 42 are respectively It consists of a large lift cam with a relatively large lift amount and a small lift cam with a relatively small lift amount.

  In the variable valve operating apparatus 2, the cam carrier 4 is operated from the first position P1 at which the intake valve 13 is operated by the high speed cam 41 as the large lift cam, and the intake valve 13 is operated by the low speed cam 42 as the small lift cam. The second switching cam 43B is moved from the first stopper portion 64A in the axial direction of the cam shaft 3 in a state where the second contact portion 53B of the second arm portion 53 is in contact with the second stopper portion 64B by moving to the second position P2. Is set to be larger than the second distance d from the first stopper portion 64A to the second switching pin 53A, and the third distance is obtained by subtracting the second distance d from the first distance c. a is a clearance between the pressed roller 11A, which is disposed between the cam carrier 4 and the intake valve 13 and contributes to the operation of the intake valve 13, and the nose portion 41B of the high-speed cam 41. It was set to be smaller than the modulus b.

  Thereby, when the moving distance in the axial direction of the cam carrier 4 is larger than a specified value, the cam carrier is formed by the first stopper portion 64A and the second stopper portion 64B, and the first contact portion 52B and the second contact portion 53B. 4 is set to the first position P1 or the second position P2, which is a predetermined position, and when the first switching pin 52A or the second switching pin 53A moves to the guide groove 43 side, only one of them is surely It can be inserted into the guide groove 43. For this reason, even if it is a simple structure, the reliability of the variable valve apparatus 2 can be improved.

  Further, in a state where a predetermined load or more is applied to the cam carrier 4, the cam carrier 4 moves from the first position P1 to the second position P2, and the first arm portion 52 contacts the first stopper portion 64A vigorously. Even when the cam carrier 4 moves from the low-speed cam 42 to the high-speed cam 41 with respect to the pressed roller 11A for operating the intake valve 13 due to the reaction of the first arm portion 52 contacting the first stopper portion 64A. In this embodiment, since the gap dimension b is larger than the third distance a, the second switching pin 53A and the second switching cam 43B can be brought into contact with each other, and the pressed roller 11A and the nose portion of the high-speed cam 41 can be brought into contact with each other. The contact with 41B can be prevented. Thereby, the variable valve apparatus 2 can be driven stably, and the reliability of the variable valve apparatus 2 can be further improved.

  While embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

  DESCRIPTION OF SYMBOLS 1 ... Cylinder head, 2 ... Variable valve apparatus, 3 ... Cam shaft, 3P ... Center point, 4 ... Cam carrier, 4A ... Outer peripheral surface, 5 ... Cam switching mechanism, 10 ... Internal combustion engine, 11A ... Pressed roller (roller) ), 13 ... Intake valve (valve), 41 ... High speed cam (first cam), 41B ... Cam nose (cam peak), 42 ... Low speed cam (second cam), 43 ... Guide groove, 43A ... First switching cam 43B ... second switching cam, 51 ... cam switching member, 52 ... first arm portion, 52B ... first contact portion (first enlarged portion), 53 ... second arm portion, 53B ... second contact portion (second) (Enlarged portion), 55 ... control shaft, 55A ... rotation center axis, 55P ... center point, 64A ... first stopper portion (first restricting portion), 64B ... second stopper portion (second restricting portion), a ... third Distance, b ... Gap size, c ... First distance, d ... Second distance, L1 ... First virtual , L2 ... second virtual line, L3 ... straight, .theta.1 ... first angle, .theta.2 ... second angle

Claims (3)

A camshaft rotatably supported on the cylinder head;
Provided to be coaxial with the camshaft, rotate integrally with the camshaft and movable in the axial direction of the camshaft, and formed on the outer peripheral surface to have different valve operating characteristics A cam carrier in which the first cam and the second cam are installed adjacent to each other,
In a variable valve operating apparatus for an internal combustion engine that switches the cam that operates the valve by moving the cam carrier in the axial direction of the cam shaft,
The cam carrier is movable between a first position where the valve is operated by the first cam and a second position where the valve is operated by the second cam;
A single guide groove is formed on the outer peripheral surface of the cam carrier so as to go around the cam carrier,
The guide groove includes a first switching cam for moving the cam carrier to the first position and a second switching cam for moving the cam carrier to the second position, and has a pair of side walls facing each other.
A control shaft having a rotation center axis and swinging around the rotation center axis is arranged to extend parallel to the cam shaft,
A cam switching member having a first arm portion and a second arm portion facing the control shaft across the cam carrier is provided so as to be rotatable integrally with the control shaft,
Provided at the tip of the first arm portion is a first protrusion that can be inserted into the guide groove as the control shaft swings, and that can contact the first switching cam.
Provided at the tip of the second arm portion is a second protrusion that can be inserted into the guide groove along with the swing of the control shaft and that can contact the second switching cam;
As the control shaft swings, one of the first arm portion or the second arm portion moves away from the guide groove in the swing direction of the control shaft, and the first arm portion or the When the other of the second arm portions moves in a direction approaching the guide groove in the swing direction of the control shaft,
Immediately before the insertion direction tip of the first protrusion or the insertion direction tip of the second protrusion is inserted into the guide groove,
The distal end portion in the insertion direction of the first protrusion and the distal end portion in the insertion direction of the second protrusion are positioned on the opposite side of the guide groove with respect to the outer peripheral surface of the cam carrier in the circumferential direction of the control shaft. A variable valve operating apparatus for an internal combustion engine, wherein a gap is formed between the cam carrier and an outer peripheral surface of the cam carrier. When the control axis is viewed from the axial direction,
A first angle formed by a straight line passing through the central point of the control shaft and the central point of the cam shaft and a first imaginary line extending along the first arm portion and intersecting the straight line;
When the second angle formed by the straight line and the second imaginary line extending along the second arm portion and intersecting the straight line is equal,
A first gap is formed between the leading end of the first protrusion in the insertion direction and the outer peripheral surface of the cam carrier, and between the leading end of the second protrusion in the insertion direction and the outer peripheral surface of the cam carrier. A second gap is formed in
The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the first gap and the second gap are set to be equal. In the cam carrier,
A first restricting portion that is located on the opposite side of the second switching cam from the first switching cam and rises radially outward from the outer peripheral surface of the cam carrier;
A second restricting portion that is located on the opposite side to the second switching cam with respect to the first switching cam and rises radially outward from the outer peripheral surface of the cam carrier;
Forming a first enlarged portion on the first arm portion that expands in the axial direction of the cam carrier from the first protrusion toward the first restricting portion;
Forming a second enlargement portion on the second arm portion that expands from the second protrusion portion toward the second restricting portion in the axial direction of the cam carrier;
The first cam and the second cam are respectively composed of a large lift cam having a relatively large lift amount and a small lift cam having a relatively small lift amount,
The cam carrier moves from a first position where the valve is operated by the first cam as the large lift cam to a second position where the valve is operated by the second cam as the small lift cam. In a state where the second enlarged portion of the second arm portion is in contact with the second restricting portion,
A first distance from the second restricting portion to the second switching cam in the axial direction of the cam shaft is set to be larger than a second distance from the second restricting portion to the second projecting portion; and ,
A third distance obtained by subtracting the second distance from the first distance is a roller disposed between the cam carrier and the valve to contribute to the operation of the valve, and a cam peak portion of the first cam. The variable valve operating apparatus for an internal combustion engine according to claim 1 or 2, wherein the variable valve operating apparatus is set to be smaller than a clearance dimension between them.

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