JP2013060823A - Variable valve gear for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable valve gear for an internal combustion engine which is reduced size and easily manufactured, prevents a failure in the operation of a valve even if the timing of switching between cams is delayed in the rotation of a camshaft.SOLUTION: The variable valve gear for the internal combustion engine includes: a cam carrier 4 axially movable with respect to the camshaft 3; a low-speed cam 41 and a high-speed cam 42 which have common base circle parts 41A, 42A allowing the axial movement of a cam carrier 4 when being in contact with a pressed roller of a rocker arm 11, and noses 41B, 42B different in shape; plungers 5 moving the cam carrier 4 in an axial direction to switch the low-speed cam 41 and the high-speed cam 42 as to be a cam opposed to a rocker arm 11; and a guide mechanism 60 forcibly moving the cam carrier 4 to a position where either the low-speed cam 41 or the high-speed cam 42 is opposed to the pressed roller 11A when the nose parts 41B, 42B get close to the pressed roller 11A before the axial movement of the cam carrier 4 is finished.

Description

  The present invention relates to a variable valve operating apparatus for an internal combustion engine.

  2. Description of the Related Art Conventionally, a variable valve device for an internal combustion engine is known in which a spiral groove is formed on the lateral outer periphery of two types of large and small cams formed on a cam carrier for changing valve timing and lift amount. (For example, refer to Patent Document 1). This variable valve operating apparatus is operated by inserting / removing a pin of an operation member into / from a spiral groove from the radial direction of the cam carrier, and the cam carrier is moved in the axial direction with respect to the cam shaft in accordance with the operation. Is to be switched.

Japanese Patent No. 3980699

  However, the conventional variable valve device described above requires a space for forming a spiral groove whose orbit changes in the cam shaft direction on the outer peripheral surface of the cam carrier. Therefore, when such a variable valve apparatus is employed, there is a problem that the overall length of the engine becomes long. In addition, since the operation member for inserting and removing the pin in the spiral groove needs to be disposed above the cam carrier in the cylinder head, there is a problem that the cylinder head becomes large.

  Further, the variable valve device has a problem that it is necessary to accurately form a spiral groove on the outer peripheral surface of the cam, which makes it difficult to manufacture and increases the cost.

  Further, in the above variable valve operating apparatus, it is considered that when the operation timing is deviated due to a malfunction of the drive system on the operation member side, an operation such as the pin being pulled out early with respect to the spiral groove may occur. . In this way, when the pin is removed early from the spiral groove, the cam switching is interrupted in the middle, so the stepped portion between the adjacent cams becomes a valve side member such as a rocker arm (valve operating member). There was a risk of malfunction of the valve due to contact.

  The present invention has been made in view of the above problems, and can be downsized and manufactured easily, and prevents the occurrence of valve malfunction even when the cam switching timing is delayed during rotation of the camshaft. An object is to provide a variable valve operating apparatus for an internal combustion engine.

  In order to solve the above-described problems and achieve the object, one aspect of the present invention includes a camshaft rotatably supported on the cylinder head side, and a camshaft fitted to the camshaft so as to be integrated with the camshaft. A cam carrier that rotates and is movable in the axial direction with respect to the cam shaft, and is provided adjacent to the outer peripheral surface of the cam carrier along the axial direction, and when the cam carrier comes into contact with the valve-side member, the axial direction of the cam carrier A plurality of cams having a common base circle that allows the movement of each of them and a nose portion having a different shape, and a cam switching drive unit that switches the cam by moving the cam carrier along the axial direction, A guide mechanism for forcibly moving the cam carrier to a position where any one cam faces the valve side member when the nose portion approaches the valve side member before the axial movement of the cam carrier is completed; The Characterized in that it obtain.

  In the above aspect, the guide mechanism includes a guide groove formed so as to circulate around the outer peripheral surface of the cam carrier, and a partial area in the circumferential direction of the guide groove. A guide wall formed so as to rise from the bottom of the guide groove so as to be divided into guide passages, and is fixed to the cylinder head side and moves relative to the guide passage as the cam carrier rotates. A guide piece passing through the passage, and when the guide piece is located in any one of the guide passages, one of the cams is set to face the valve side member, and the cam carrier When the nose portion approaches the valve side member before the axial movement of the guide member is completed, the guide wall is guided to the side of the guide piece by the guide piece, and the guide piece becomes one of the guide passages. Ri may be set with the structures to be separated.

  In the above aspect, an end cam surface having a height difference in the axial direction is formed on the end surface in the axial direction of the cam carrier so that the cam switching drive portion reciprocates along the axial direction of the cam shaft. It is good also as a structure which has a movable part which can move and this movable part presses an edge part cam surface.

  As the above aspect, the end cam surface has a carrier non-drive portion where the cam carrier is not moved by the movable portion, a carrier drive portion that moves the cam carrier when the movable portion contacts, and the cam carrier moves as much as possible. A carrier maximum drive portion that stops at the position where the movable portion faces the carrier non-drive portion when the nose portion contacts the valve side member, and the base circle portion contacts the valve side member. It can be set as the structure set so that a movable part may oppose a carrier drive part or a carrier largest drive part.

  As the above aspect, the nose portion is connected to the valve side member in a state where the maximum carrier driving portion and the carrier driving portion pass through a position facing the movable portion and the carrier non-driving portion faces the movable portion. It is preferable to set so that the guide wall reaches the guide piece before contact.

  As the above aspect, it is preferable that the end portions of the guide wall and the guide piece that are in contact with each other and are guided are formed in a pointed shape.

  According to the variable valve operating apparatus for an internal combustion engine according to the present invention, the internal combustion engine can be reduced in size and manufactured easily, and even if the cam switching timing is delayed during rotation of the camshaft, the occurrence of valve malfunction is prevented. The variable valve operating apparatus can be realized.

FIG. 1 is a cross-sectional view of a cylinder head provided with a variable valve operating apparatus for an internal combustion engine according to an embodiment of the present invention. FIG. 2 is a perspective view of the variable valve operating apparatus for an internal combustion engine according to the embodiment of the present invention. FIG. 3 is an exploded perspective view of the variable valve operating apparatus for an internal combustion engine according to the embodiment of the present invention. FIG. 4 is a perspective view showing a state in which the variable valve operating apparatus for the internal combustion engine according to the embodiment of the present invention is supported by the lower cam housing and the upper cam housing. FIG. 5 is a perspective view showing a cam shaft in the variable valve operating apparatus for an internal combustion engine according to the embodiment of the present invention. FIG. 6 is a plan view of the variable valve operating apparatus for an internal combustion engine according to the embodiment of the present invention. FIG. 7 is a side view of the variable valve operating apparatus for an internal combustion engine according to the embodiment of the present invention. FIG. 8 is a cross-sectional view taken along the line VIII-VIII in FIG. 1, showing a state where the guide piece and the guide wall are in contact with each other to guide each other. FIG. 9 is a cross-sectional view taken along line VIII-VIII in FIG. 1, showing a state in which the guide wall is located on the side of the guide piece. FIG. 10-1 is a cross-sectional view showing a state where the base circle portion of the high-speed cam is in contact with the pressed roller of the rocker arm, taken along line XX in FIG. 10-2 is a cross-sectional view showing a state where the nose portion of the high-speed cam is in contact with the pressed roller of the rocker arm, taken along line XX in FIG. 10-3 is a cross-sectional view showing a state where the piston of the plunger is protruded in the state shown in FIG. 10-2, taken along line XX in FIG. 4. FIG. 10-4 shows a state in which the cam carrier rotates in the state of FIG. 10-3, the cam carrier moves by the action of the end cam surface and the piston, and the low-speed cam contacts the pressed roller of the rocker arm. It is sectional drawing which shows the state cut | disconnected by the XX line of FIG. 10-5 shows a state where the cam carrier rotates in the state shown in FIG. 10-4 and the nose portion of the low-speed cam is in contact with the pressed roller of the rocker arm, and is cut along line XX in FIG. FIG. FIG. 11A is a side view of the variable valve operating apparatus showing a state in which the nose portion of the high-speed cam contacts the pressed roller of the rocker arm to lift the valve and the guide wall is positioned on the side of the guide piece. is there. FIG. 11-2 is a side view of the variable valve operating apparatus showing a state in which the base circle portion of the high-speed cam is in contact with the pressed roller of the rocker arm and the guide wall is separated from the guide piece. FIG. 11-3 is a side view of the variable valve operating apparatus in which the base circle portion of the high-speed cam contacts the pressed roller of the rocker arm, the guide wall is completely separated from the guide piece, and the cam carrier is movable in the axial direction. FIG. FIG. 11-4 is a side view of the variable valve operating apparatus when the front end of the guide wall reaches the guide piece as the cam carrier rotates. FIG. 12 is a timing chart showing changes in the stroke of the cam carrier, the height of the guide wall, and the valve lift amount. FIG. 13 is a timing chart showing changes in valve lift amount A1, end cam surface height A2, plunger stroke A3, and cam carrier movement amount (including incomplete movement) A4.

  Details of a variable valve operating apparatus for an internal combustion engine according to an embodiment of the present invention will be described below with reference to the drawings.

(Schematic configuration of variable valve operating device)
As shown in FIG. 1, a variable valve operating apparatus 2 for an internal combustion engine according to an embodiment of the present invention is built in a cylinder head 1 of the internal combustion engine. The overall configuration of the cylinder head 1 is substantially the same as that of a normal cylinder head, and includes a head body 1A and a head cover 1B. An intake valve 13 is provided in the head main body 1A so as to be able to advance and retreat in the axial direction by a valve guide (not shown) on the head main body 1A side. The intake valve 13 is urged by a valve spring 14 in a pulling direction (a direction in which the intake port and the combustion chamber are closed).

  As shown in FIGS. 2 to 4, the variable valve apparatus 2 includes a cam shaft 3, a cam carrier 4 in which a low speed cam 41 and a high speed cam 42 are provided adjacent to each other, and a cam carrier 4. And a pair of plungers 5 as cam switching drive portions disposed opposite to each other. As shown in FIGS. 1, 6, and 7, the variable valve apparatus 2 includes a guide mechanism 60 provided between the cam carrier 4 and the cylinder head 1 side. 6 is a plan view of the variable valve apparatus 2, and FIG. 7 is a side view of the variable valve apparatus 2.

  Such a variable valve apparatus 2 switches between the low speed cam 41 and the high speed cam 42 in order to change the lift state of the intake valve 13. Further, as shown in FIG. 1, the cylinder head 1 is further provided with a cam shaft 30 on the exhaust valve side, an exhaust cam 40, and the like.

  As shown in FIGS. 1 to 3, in the present embodiment, a rocker arm 11 is used as a valve side member that swings as the cam carrier 4 rotates. The rocker arm 11 is disposed such that a recess formed on the lower surface of the one end 11C abuts on the pivot 12A. In other words, the rocker arm 11 is supported by a pivot 12A that is a swing center (fulcrum) on the one end 11C side. The pivot 12A is provided on the cylindrical pivot support 12 so as to be adjustable.

  At the center of the rocker arm 11, a pressed roller 11A is pivotally supported by a pin 11B. The pressed roller 11 </ b> A protrudes from the upper surface of the rocker arm 11 and comes into contact with either the low speed cam 41 or the high speed cam 42 of the cam carrier 4. 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. In the present embodiment, the lower surface of the arm tip portion 11D is in contact with the upper end of the intake valve 13, but the valve clearance adjuster may naturally protrude from the lower surface of the arm tip portion 11D.

(Cam shaft)
As shown in FIGS. 1 and 4, the cam shaft 3 is rotatably supported by a lower cam housing 6 and an upper cam housing 7 that serve as bearings disposed on the head main body 1 </ b> A. An interlocking portion is provided so as to rotate in conjunction with a crankshaft (not shown). In the variable valve operating apparatus 2 according to the present embodiment, illustration of the interlocking portion in the camshaft 3 is omitted. The lower cam housing 6 and the upper cam housing 7 are disposed at positions that do not overlap with a cylinder of an internal combustion engine (not shown), and are installed on the head body 1A as shown in FIG. The lower cam housing 6 and the upper cam housing 7 are covered with a head cover 1B and built in the cylinder head 1.

  The rotational speed of the camshaft 3 is set to be ½ of the rotational speed of the crankshaft, for example. In the present embodiment, the camshaft 3 is arranged so as to extend along the front-rear direction of the engine (not shown) as the internal combustion engine (the direction indicated by the arrows in FIGS. 2 to 4).

  As shown in FIG. 5, the camshaft 3 has a cylindrical shape, and is formed with a first oil passage 33 and a second oil passage 34 that are formed along the axial direction and partitioned from each other. A spline external tooth 31 having a predetermined width dimension in the axial direction is formed around the outer peripheral surface of the central portion of the camshaft 3. A flat portion 32 that is flat along the axial direction is formed in a part of the spline outer teeth 31. At two central positions of the flat portion 32, concave portions 32A and 32B for positioning the cam carrier 4 are formed along the axial direction with a predetermined distance therebetween.

  As shown in FIG. 5, the first oil groove 35 and the second oil groove 36 are formed around both sides in the axial direction of the region where the spline external teeth 31 are formed in the camshaft 3. As shown in FIG. 4, the region where the first oil groove 35 and the second oil groove 36 are formed in the camshaft 3 is freely rotatable at the bearing portion between the lower cam housing 6 and the upper cam housing 7 described above. It is supported by.

  As shown in FIG. 10A, the first oil groove 35 is formed with a communication hole 33 </ b> A that communicates with the first oil passage 33. A communication hole 34 </ b> A that communicates with the second oil passage 34 is formed in the second oil groove 36. The first oil groove 35 and the second oil groove 36 have a function of supplying lubricating oil to the bearing portion between the lower cam housing 6 and the upper cam housing 7 shown in FIG.

(Cam carrier)
As shown in FIG. 3, the cam carrier 4 is formed in a cylindrical shape so as to surround the cam shaft 3. On the inner peripheral surface of the cam carrier 4, spline inner teeth 45 that mesh with the spline outer teeth 31 of the cam shaft 3 are formed. For this reason, the cam shaft 3 and the cam carrier 4 rotate together, and the cam carrier 4 can move in the axial direction with respect to the cam shaft 3.

  As shown in FIGS. 2 to 4, the cam carrier 4 includes a low-speed cam 41 as a first cam and a high-speed cam 42 as a second cam, which have different valve operating characteristics on the circumferential surface, and are integrated in an axial direction. Is provided. In the present embodiment, as shown in FIGS. 2 to 4, a pair of the integrally configured body of the low speed cam 41 and the high speed cam 42 is arranged at a predetermined interval in the cam carrier 4. When a pair of low-speed cams 41 and 41 is selected, each low-speed cam 41 is positioned above the intake valve 13 (rocker arm 11), and when a pair of high-speed cams 42 is selected, each high-speed cam 41 is selected. The intervals between the low-speed cams 41, the intervals between the high-speed cams 42, and the intervals between the intake valves 10 are set to be the same so that 42 is positioned above the intake valve 13 (rocker arm 11).

  As shown in FIG. 4, the low-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 high-speed cam 42 protrudes from the nose portion 41B of the low-speed cam 41 toward the outer side in the radial direction from the base circle portion 42A and the base circle portion 42A having the same radius as the base circle portion 41A of the base low-speed cam 41. And a formed nose portion 42B. As shown in FIG. 4, the low-speed cam 41 and the high-speed cam 42 are disposed adjacent to each other along the axial direction. Moreover, these base circular portions 41A and 42A are continuous surfaces formed flush with each other in the axial direction. Further, the nose portions 41B and 42B of the low-speed cam 41 and the high-speed cam 42 are arranged in a direction having substantially the same phase. The low-speed cam 41 and the high-speed cam 42 are configured so that the lift timing of the intake valve 13 that operates in accordance with the operation of a crankshaft (not shown) is defined by the arrangement state with respect to the camshaft 3.

  Further, an end cam surface 43 having a height difference in the axial direction is formed on the end surface in the axial direction of the cam carrier 4 so as to circulate and continue. The end cam surface 43 is opposed to the tip of a piston 51 as a movable part of the plunger 5 that reciprocates along the cam shaft direction. The cam carrier 4 moves in the cam shaft direction when the end cam surface 43 is pressed by the piston 51 of the plunger 5. Note that the tip of the piston 51 of the plunger 5 is operated to move in and out between two points of the most protruding position and the most retracted position.

  As shown in FIG. 4, the end cam surface 43 includes a non-drive portion 43A having a low cam height in the axial direction, a maximum drive portion 43B having the highest cam height in the axial direction, and a rotation direction of the maximum drive portion 43B. Drive units 43C and 43D located in front of and behind. The drive unit 43C is located on the front side in the rotation direction a of the cam carrier 4 with respect to the maximum drive unit 43B. The drive unit 43D is located on the rear side in the rotation direction a of the cam carrier 4 with respect to the maximum drive unit 43B. And the drive part 43C of the front side of the rotation direction a is set more gently than the drive part 43D.

  As shown in FIG. 3, a through-hole 44 </ b> A for providing a click moving member is formed in the intermediate portion 44 of the cam carrier 4 so as to penetrate in the radial direction of the cam carrier 4. The through hole 44A has a ball 8 as a click moving member, a spring 9 that urges the ball 8 so as to protrude from the inner peripheral surface of the cam carrier 4 toward the central axis, and a through hole 44A. And a plug 10 that supports the outer end of the spring 9. When the cam carrier 4 moves in the axial direction with respect to the cam shaft 3, the ball 8 is engaged with the recesses 32A and 32B provided on the cam shaft 3 side with a click operation for positioning. ing.

(Plunger)
As shown in FIG. 4, the plunger 5 is built in the lower cam housing 6. FIG. 4 shows only one (front) lower cam housing 6 and upper cam housing 7 of the pair of plungers 5, but the other plunger 5 is also built in the lower cam housing 6. . As shown in FIGS. 10-1 to 10-5, the lower cam housing 6 houses the piston 51 of the plunger 5, and is formed with a piston sliding hole 6A through which the piston 51 can move in the axial direction. The piston 51 is urged by a spring 52 in the direction of sunk in the piston sliding hole 6A. In the plunger 5, for example, fluid such as oil is supplied and discharged from an actuator (not shown) between the head of the piston 51 and the plug 53 via, for example, the first oil passage 33 and the second oil passage 34. Thus, the piston 51 is caused to appear and disappear from the piston sliding hole 6A. The piston 51 presses the cam carrier 4 and is driven at an appropriate switching timing so that either the low speed cam 41 or the high speed cam 42 corresponds to the rocker arm 11.

(Guide mechanism)
As shown in FIG. 1, the guide mechanism 60 is provided between the cam carrier 4 and the head body 1A. As shown in FIG. 6, the guide mechanism 60 includes a guide groove 61 provided on the cam carrier 4 side and a guide piece 62. As shown in FIG. 1, the guide piece 62 protrudes from the head body 1 </ b> A of the cylinder head 1. The guide piece 62 can relatively pass through the guide groove 61 as the cam carrier 4 rotates.

  As shown in FIG. 6, the guide groove 61 is formed to circulate around the outer periphery of the portion of the cam carrier 4 adjacent to the intermediate portion 44 in the axial direction. From the bottom of the guide groove 61, a part of the circumferential direction of the guide groove 61 is divided into guide passages 61 </ b> A of the number of cams (2 in the present embodiment) in the groove width direction (axial direction). A guide wall 61B is provided to stand up.

  FIG. 8 is a cross-sectional view taken along the line VIII-VIII in FIG. 1 and shows a state in which the guide piece 62 is cut and the guide groove 61 is viewed. As shown in FIG. 8, when the width dimension of the guide passage 61 is W1, a guide wall 61B having a predetermined length extends along the rotational direction a in the center of the guide passage 61 in the groove width direction (axial direction of the cam carrier 4). Is provided. The width dimension W2 of the two guide paths 61A formed by dividing the guide path 61 by the guide wall 61B is set longer than the width dimension W3 of the guide piece 62 so that the guide piece 62 can pass relatively. Has been.

  As shown in FIG. 8, when the front end 61Bf of the guide wall 61B in the rotation direction (cam carrier rotation direction) a reaches the position of the tip 62A of the guide piece 62, the low speed cam 41 and the nose portion 41B of the high speed cam 42 are provided. 42B, the front end 61Bf of the guide wall 61B is arranged and set so that it is in a state before contacting the pressed roller 11A of the rocker arm 11. The position of the front end portion 61Bf of the guide wall 61B is determined by the positional relationship with the guide piece 62 fixed to the cylinder head 1 side. Here, the state before the nose portions 41B and 42B of the low speed cam 41 and the high speed cam 42 contact the pressed roller 11A of the rocker arm 11 is the base circle portions 41A and 42A of the low speed cam 41 and the high speed cam 42. Is in contact with the pressed roller 11A.

  In this embodiment, when the nose parts 41B and 42B approach the pressed roller 11A before the axial movement of the cam carrier 4 is completed, as shown in FIG. Guided in the direction of the white arrow in the figure, the side of the guide piece 62, that is, the cam carrier 4 is forcibly guided in the axial direction b (indicated by the arrow in FIG. 8). As a result, the guide piece 62 is guided. It is distributed to any one of the passages 61A. Therefore, in the present embodiment, the guide wall 61B passes through the side of the guide piece 62 so that the guide piece 62 can be easily distributed to either of the guide passages 61A on both sides thereof. And the edge part of the guide piece 62 is formed in the pointed shape.

  As shown in FIG. 9, when the guide piece 62 is located in one guide passage 61A, the low speed cam 41 is set to face the rocker arm 11, and the guide piece 62 is set to the other guide passage. The high speed cam 42 is set so as to face the rocker arm 11 when it is located within 61A. For this reason, when the guide piece 62 enters one of the guide passages 61A, the low speed cam 41 or the high speed cam 42 is in a position corresponding to the rocker arm 11, and the boundary portion between the low speed cam 41 and the high speed cam 42 is the rocker arm 11. It is not placed in the corresponding position.

  Originally, in the variable valve operating apparatus 2, at the timing when the nose portions 41B and 42B come into contact with the pressed roller 11A of the rocker arm 11, one of the low speed cam 41 or the high speed cam 42 corresponds to the pressed roller 11A of the rocker arm 11. Placed in. However, for example, if a malfunction such as a decrease in the drive hydraulic pressure of the plunger 5 occurs and the timing at which the piston 51 presses the end cam surface 43 is delayed, the cam carrier 4 stops before the movement is completed. End up. In such a case, a step between the nose portions 41B and 42B of the low-speed cam 41 and the high-speed cam 42 may come into contact with the rocker arm 11 side to cause problems such as malfunction.

  By providing the guide mechanism 60 of the present embodiment, even when the movement of the cam carrier 4 stops halfway as described above, one of the low speed cam 41 or the high speed cam 42 is placed at a fixed position corresponding to the rocker arm 11 side. It is possible to avoid the occurrence of malfunction due to the reliable movement. Therefore, the operation reliability of the variable valve apparatus 2 can be improved. In such a guide mechanism 60, it is possible to perform a normal cam switching operation when the drive hydraulic pressure of the plunger 5 returns to normal thereafter.

  When there is no problem with the plunger 5 or the like, the desired low speed cam 41 or the high speed cam 42 is disposed at a position facing the rocker arm 11. In this case, as shown in FIG. 9, when either one of the nose portions 41B or 42B is in contact with the pressed roller 11A of the rocker arm 11, the guide piece 62 is located on the side of the guide wall 61B. Therefore, the guide piece 62 prevents the cam carrier 4 from moving in the axial direction. For this reason, for example, in a state where the high-speed cam 42 faces the rocker arm 11, the cam carrier 4 is prevented from moving in the axial direction while the nose portion 42B is in contact with the pressed roller 11A. Therefore, the nose portion 42B falls to the side of the pressed roller 11A and the nose portion 41B of the low-speed cam 41 collides with the rocker arm 11 side, or the cam carrier 4 comes into contact with the pressed roller 11A in an unstable state. Can be prevented.

(Operation and operation of variable valve system)
Hereinafter, the switching operation from the low speed cam 41 and the high speed cam 42 of the variable valve operating apparatus 2 according to the present embodiment to FIGS. 10-1 to 10-5, FIGS. 11-1 to 11-4, FIG. This will be described with reference to FIG. FIGS. 10-1 to 10-5 are cross-sectional views showing each state in which the variable valve apparatus is cut along the line XX of FIG. 11-1 to 11-4 are side views showing various states of the variable valve apparatus 2, and FIG. 12 is a bottom view of the guide groove 61 at a position where the stroke of the cam carrier 4 and the guide piece 62 face each other. FIG. 13 is a timing chart showing changes in the height (including the height of the guide wall 61B) and changes in the valve lift amount. FIG. 13 shows the valve lift amount A1, the end cam surface height A2, the plunger stroke A3, and the cam carrier. It is a timing chart which shows the change of A4 movement amount (including the case of incomplete movement) A4.

  FIG. 10A shows a state where the high speed cam 42 is selected and operated in the variable valve operating apparatus 2. At this timing, the base circle portion 42A of the high-speed cam 42 and the pressed roller 11A of the rocker arm 11 are in contact with each other. In the state shown in FIG. 10A, the guide piece 62 in the guide mechanism 60 is in a state of being disposed in the guide groove 61. In such a state where the high-speed cam 42 is selected, the ball 8 which is a positioning means for performing the click operation is engaged with the recess 32A provided on the cam shaft 3 side for positioning.

  FIG. 10-2 shows that the nose portion 42B presses the pressed roller 11A of the rocker arm 11 and lifts the valve 13 (large lift) when the cam carrier 4 rotates while the high-speed cam 42 is selected. It shows the state. In this state where the nose portion 42B is in contact with the pressed roller 11A, when the high speed cam 42 corresponds to a position appropriately facing the rocker arm 11 as shown in FIG. The guide piece 62 is arranged in the guide passage 61A where the should be arranged. At this time, in the timing chart shown in FIG. 12, it corresponds to the time point T1, and from the predetermined time before the valve 13 starts to lift until the time point T2 when the lift amount of the valve 13 becomes 0, the guide groove 61 facing the guide piece 62. The guide wall 61B is in an upright state. For this reason, the cam carrier 4 is in a state where movement in the axial direction is prevented by the guide piece 62. Therefore, as shown in FIG. 12, the stroke of the cam carrier 4 at this time is zero.

  Next, when switching from the state where the high-speed cam 42 is selected to the state where the low-speed cam 41 is selected, in the state shown in FIG. 10-2, the side where the low-speed cam 41 is located (FIG. 10-2). The piston 51 of the plunger 5 on the right side in FIG. 10 is driven to protrude from the piston sliding hole 6A, and the state shown in FIG. As shown in FIG. 10-3, at this time, the tip of the piston 51 is at a position closest to the non-drive portion 43 </ b> A of the end cam surface 43.

  When the cam carrier 4 rotates in this state, the base circle portion 42A starts to come into contact with the pressed roller 11A through the state shown in FIG. Accordingly, the drive part 43C and the maximum drive part 43B on the front side in the rotational direction of the end cam surface 43 slide with the tip part of the piston 51. Such an operation is performed in a period of time T2 to T3 in FIG. As a result, the cam carrier 4 moves by about the height dimension in the axial direction of the maximum drive portion 43B by a reaction from the tip portion of the piston 51 whose position is fixed.

  At this time, as shown in FIG. 10-4, since the base circle portion 41A of the low speed cam 41 is formed flush with the base circle portion 42A of the high speed cam 42, the cam carrier 4 is in contact with the pressed roller 11A. The base circle portion 41A of the low-speed cam 41 comes into contact with the pressed roller 11A by sliding smoothly. At this time, as shown in FIG. 11C, the guide wall 61 </ b> B rotates and moves to a position away from the guide piece 62. For this reason, since the cam carrier 4 is not restricted by the guide piece 62, the cam carrier 4 moves along the axial direction as shown in FIG. Be placed.

  Thus, when the cam carrier 4 is displaced with respect to the cam shaft 3, the ball 8 engaged with the recess 32A of the cam shaft 3 is disengaged from the recess 32A, and as shown in FIG. Move to engage. As a result, the cam carrier 4 is fixed to the cam shaft 3 at a position where the low speed cam 41 is selected.

  As shown in FIG. 10-4, the rotation of the cam carrier 4 starts when the base circle portion 41A of the low-speed cam 41 is in contact with the pressed roller 11A, and the nose portion 41B is pressed by the pressed roller 11A as shown in FIG. 11-4. When the state approaches, the front end portion 61Bf of the guide wall 61B approaches the end portion of the guide piece 62, and the guide piece 62 relatively passes through the guide passage 61A on the side of the guide wall 61B as shown in FIG. To do. When the cam carrier 4 further rotates, as shown in FIG. 10-5, the nose portion 41B comes into contact with the pressed roller 11A and lifts the valve 13 (small lift). At this time, as shown in FIG. 10-5, since the guide piece 62 exists in the corresponding one guide passage 61A, the movement of the cam carrier 4 in the axial direction in this state can be prevented.

  As shown in FIG. 10-2, if a force for switching from the high-speed cam 42 to the low-speed cam 41 works when the nose portion 42B of the high-speed cam 42 is in contact with the pressed roller 11A of the rocker arm 11, The step between the two cams comes into contact with the rocker arm 11 and causes problems such as noise and breakage. However, in the variable valve operating apparatus 2 according to the present embodiment, as shown in FIG. 10-3, the guide piece 62 is located in the corresponding one guide passage 61A. Switching to the cam 41 is prevented.

  As shown in FIG. 10-5, in order to switch from the state in which the low speed cam 41 contacts the pressed roller 11A to the high speed cam 42, the piston 51 of the plunger 5 on the right side of the drawing is retracted and the piston 51 of the plunger 5 on the left side of the drawing. May be projected at a predetermined timing according to the structure of the left end cam surface 43 in the drawing. In this way, the piston 51 of the plunger 5 is switched by projecting so that the maximum drive portion 43B contacts the tip of the piston 51 at the timing when the base circle portions 41A and 42A are in contact with the pressed roller 11A. Is possible.

  FIG. 13 is a timing chart showing changes in the valve lift amount A1, the height A2 of the end cam surface 43, the stroke A3 of the plunger 5, and the movement amount A4 of the cam carrier 4. In FIG. 13, the two-dot chain line in (1) indicates the normal timing of the operation of the plunger 5, and the solid line in (2) indicates a case in which the operation of the plunger 5 is delayed. When the plunger 5 is operated at the time Ta1 of the normal timing as indicated by the two-dot chain line of (1), the cam carrier 4 is indicated by the two-dot chain line of the time Ta2 to Ta3 and the movement amount A4 is indicated by (1A). Thus, the distance L1 moves and the cam is switched. However, when the plunger 5 is operated with a delay of time Tb1 as indicated by the solid line (2), the cam carrier 4 has a short movement amount A4 between times Tb2 to Tb3 as indicated by the solid line (2A). Only move, cam switching is not complete. In the variable valve operating apparatus 2 according to the present embodiment, the cam carrier 4 is forcibly moved from the time Tb4 to the distance L1 by the guide mechanism 60 as shown by the solid line in FIG. As indicated by the one-dot chain line in (3-2), it is forcibly moved to the distance 0 (original position). Thus, as shown in FIG. 13, the forcible movement of the cam carrier 4 is set to be completed at a time Tb5 before the time TL1 at which the valve lift is started. Note that the timing for forcibly moving the cam carrier 4 to prevent malfunction of the valve as described above is set based on the mutual positional relationship between the nose portions 41B and 42B, the guide wall 61B, the guide piece 62, and the like. Can do.

  For example, the timing of switching from the high-speed cam 42 to the low-speed cam 41 when the camshaft 3 rotates at high speed, such as when the timing at which the tip of the piston 51 protrudes is delayed and hits the drive unit 43D on the downside of the end cam surface 43. Is delayed, the low-speed cam 41 cannot be moved to a position where the low-speed cam 41 properly faces the pressed roller 11A only by the action of the plunger 5.

  However, since the variable valve apparatus 2 according to the present embodiment includes the guide mechanism 60, even if the operation timing of the plunger 5 is delayed and the movement of the cam carrier 4 ends halfway as described above, the guide mechanism 60 is provided. Since the front end portion 61Bf of the wall 61B is guided to the end portion of the guide piece 62 and the guide piece 62 is relatively distributed and guided to one of the guide passages 61A on both sides of the guide wall 61B, the low speed cam 41 and the high speed cam 42 are guided. Any one of the cams is forcibly arranged at a position facing the pressed roller 11A. Accordingly, the stepped portion (the stepped portion between the nose portions 41B and 42B) straddling the low-speed cam 41 and the high-speed cam 42 comes into contact with the rocker arm 11 side (including the pressed roller 11A) to cause the valve 13 to malfunction. Can be prevented.

  In particular, in the variable valve apparatus 2 according to the present embodiment, the guide mechanism 60 has a simple configuration and can suppress an increase in the number of parts, thereby preventing malfunction of the variable valve apparatus 2 at a low cost. It becomes possible.

  Further, in the variable valve operating apparatus 2 according to the present embodiment, the drive unit 43C on the front side in the rotational direction a of the end cam surface 43 of the cam carrier 4 is inclined more than the drive unit 43D on the rear side in the rotational direction a. Since the end cam surface 43 slides with respect to the tip end portion of the piston 51, the lateral force received from the end cam surface 43 with respect to the piston 51 can be reduced. It is possible to improve the operation reliability.

  In the present embodiment, the piston 51 of the plunger 5 is configured to reciprocate in the axial direction of the cam shaft 3, and the piston 51 presses the end cam surface 43 formed on the end surface of the cam carrier 4, thereby The carrier 4 is moved in the axial direction to switch between the high speed cam 42 and the low speed cam 41. Therefore, in the variable valve apparatus 2 according to the present embodiment, the piston is spirally formed on the outer peripheral surface of the cam carrier using a plunger whose piston reciprocates in the radial direction of the cam carrier 4 as in the conventional variable valve apparatus. Compared with the configuration in which the piston is inserted into and removed from the groove formed in the above, the height of the cylinder head can be suppressed, the overall length of the cam carrier 4 can be shortened, and the internal combustion engine can be downsized. There is.

  In the variable valve operating apparatus 2 according to the present embodiment, the piston 51 of the plunger 5 is reciprocated in the same direction as the moving direction of the cam carrier 4, so that the driving force can be transmitted efficiently. Furthermore, in the present embodiment, since the plunger 5 can be disposed at a low position in the height direction of the cylinder head 1, the variable valve operating device 2 can be reduced in size.

  In the variable valve apparatus 2 according to the present embodiment, since the plunger 5 is built in the cam housing (the lower cam housing 6 and the upper cam housing 7), the number of parts such as attachment members can be reduced.

  Further, in the present embodiment, it is not a configuration in which the tip of the piston 51 is taken in and out of the groove, but it is only necessary to reciprocate the piston 51 along the axial method on the end cam surface 43, thereby simplifying the timing control. be able to. Furthermore, in this embodiment, since it is not necessary to form a spiral groove, the processing of the cam carrier 4 is facilitated, and the manufacturing efficiency of the variable valve apparatus 2 can be increased.

  According to the variable valve operating apparatus 2 according to the present embodiment, the ball 8 as the click moving member, the spring 9 and the like are used so that the cam carrier 4 is positioned by the click operation with respect to the cam shaft 3. Therefore, the cam carrier 4 can be reliably positioned. Further, the recesses 32A and 32B formed in the cam shaft 3 and the through-hole 44A formed in the cam carrier 4 need only be formed perpendicular to the cam shaft 3 and the cam carrier 4 in the radial direction. There is an advantage that it can be processed. In particular, since the ball 8, the spring 9, and the plug 10 need only be assembled from the outside into the through hole 44A formed in the cam carrier 4, the assemblability is improved and the manufacturability of the variable valve apparatus 2 is improved. it can.

(Other embodiments)
Although the embodiment has been described above, it should not be understood that the description and the drawings constituting a part of the disclosure of the embodiment limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in the above-described embodiment, the present invention is applied to the variable valve operating device that presses the end surface of the cam carrier 4 with the plunger 5 as the cam switching drive unit. However, the movement of the cam carrier is not completed. It goes without saying that the present invention can be applied to various variable valve operating devices in order to prevent malfunctions and to prevent the movement of the cam carrier during valve lift.

  In the above embodiment, the maximum drive portion 43B of the end cam surface 43 on both end surfaces of the cam carrier 4 is disposed at a position corresponding to the base circle portions 41A and 42A, and the non-drive portion 43A is placed on the nose portions 41B and 42B. Although arranged at the corresponding position, substantially when the base circular portions 41A and 42A come into contact with the pressed roller 11A of the rocker arm 11, the drive portion 43C is placed on the end cam surface 43 facing the piston 51 of the plunger 5. When the nose portions 41B and 42B come into contact with the pressed roller 11A, the non-driving portion 43A is formed on the end cam surface 43 facing the piston 51 of the plunger 5, and the driving portion 43C is formed. However, any configuration may be used as long as it is formed between the maximum drive unit 43B and the non-drive unit 43A. Therefore, in the present invention, the end cam surface 43 may be provided according to the arrangement position of the piston 51 of the plunger 5.

  In the above-described embodiment, as the plunger 5, for example, a fluid such as oil is supplied and discharged from an actuator (not shown) to cause the piston 51 to appear and disappear from the piston sliding hole 6 </ b> A. Also good.

  In the above embodiment, as shown in FIG. 10-4, when the piston 51 of the plunger 5 protrudes the most and the tip of the piston 51 moves the cam carrier 4 to the left in the figure, the cam carrier 4 side is moved. The provided ball 8 may be moved to a position where the center of the ball 8 enters the planar contour of the recess 32B without reaching the position where the ball 8 overlaps the recess 32B on the camshaft 3 side. Good. That is, the position of the recess 32B is set in advance so that the center of the ball 8 on the cam carrier 4 side pressed by the tip of the piston 51 enters the plane outline of the recess 32B without reaching the center of the recess 32B. Just set it up. Similarly, even when the cam carrier 4 is moved in the opposite direction, the position of the recess 32A may be set in advance so that the relationship between the recess 32A and the ball 8 is the same as described above.

  In this case, since the center of the ball 8 is located within the planar contour of the recess 32B, the ball 8 enters the deepest position of the recess 32B by the biasing force of the spring 9, and the cam carrier 4 is slightly extended. It is possible to move only in the left direction in the figure, and a slight clearance can be provided between the maximum drive part 43B of the cam carrier 4 and the tip part of the piston 51.

  As shown in FIG. 10-4, when the cam carrier 4 is pushed out by the piston 51 of the plunger 5 and the low-speed cam 41 is selected, the cam shaft 3 and the cam carrier 4 are rotating. If there is a slight clearance between the maximum drive portion 43B and the tip portion of the piston 51, it is possible to suppress the occurrence of friction, noise, etc. between the maximum drive portion 43B and the tip portion of the piston 51.

  In the above embodiment, the first oil passage 33 and the second oil passage 34 are formed in the camshaft 3, but various camshafts having no oil passage may be used.

DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Variable valve operating apparatus 3 Cam shaft 4 Cam carrier 5 Plunger (cam switching drive part)
6 Lower cam housing 7 Upper cam housing 11 Rocker arm (valve side member)
11A Pressed roller (valve side member)
13 Intake valve (valve)
41 Low speed cam 42 High speed cam 43 End cam surface 43A Non-drive part 43B Maximum drive part 43C, 43D Drive part 51 Piston (movable part)
60 Guide Mechanism 61 Guide Groove 61A Guide Path 61B Guide Wall 61Bf Front End 62 Guide Piece

Claims (6)

A camshaft rotatably supported on the cylinder head side;
A cam carrier that fits on the cam shaft and rotates integrally with the cam shaft and is movable in the axial direction with respect to the cam shaft;
The cam carrier is provided adjacent to the outer peripheral surface of the cam carrier along the axial direction, and has a common base circle portion that allows the cam carrier to move in the axial direction when it comes into contact with the valve side member. A plurality of cams having different nose parts;
A cam switching drive unit that moves the cam carrier along the axial direction to switch the cam; and
When the nose portion approaches the valve side member before the cam carrier is moved in the axial direction, the cam carrier is forced to a position where any one of the cams faces the valve side member. A guide mechanism to be moved;
A variable valve operating apparatus for an internal combustion engine, comprising: The guide mechanism is
A guide groove formed to circulate on the outer peripheral surface of the cam carrier;
A guide wall rising from the bottom of the guide groove so as to divide a partial region in the circumferential direction of the guide groove into guide passages of the number of the cams in the groove width direction;
A guide piece that is fixed to the cylinder head side and moves relative to the guide path as the cam carrier rotates and passes through the guide path;
When the guide piece is located in any one of the guide passages, any one of the cams is set to face the valve side member,
When the nose portion approaches the valve side member before the axial movement of the cam carrier is completed, the guide wall is guided to the side of the guide piece by the guide piece, and the guide piece is 2. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the variable valve operating apparatus is set so as to be distributed to any one of the guide passages. An end cam surface having an axial height difference is formed on the end surface in the axial direction of the cam carrier so as to go around,
The said cam switching drive part has a movable part which can reciprocate along the axial direction of the said cam shaft, and this movable part presses the said edge part cam surface, The Claim 1 or Claim 2 characterized by the above-mentioned. A variable valve operating apparatus for an internal combustion engine according to claim 1. The end cam surface includes a carrier non-driving part in which the cam carrier is not moved by contact with the movable part, a carrier driving part for moving the cam carrier by contact with the movable part, and a maximum of the cam carrier. A carrier maximum drive section that stops at a limited position,
When the nose portion contacts the valve side member, the movable portion faces the carrier non-drive portion, and when the base circle portion contacts the valve side member, the movable portion becomes the carrier drive portion or the carrier 4. The variable valve operating apparatus for an internal combustion engine according to claim 3, wherein the variable valve operating apparatus is set so as to face the maximum carrier drive section.   Before the nose portion comes into contact with the valve side member in a state where the maximum carrier driving portion and the carrier driving portion pass through a position facing the movable portion and the carrier non-driving portion faces the movable portion. The variable valve operating apparatus for an internal combustion engine according to claim 4, wherein the guide wall is set so as to reach the guide piece.   The variable valve operating apparatus for an internal combustion engine according to any one of claims 2 to 5, wherein the end portions of the guide wall and the guide piece that are brought into contact with each other and guided are formed in a pointed shape.

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