JP2014134165A - Variable valve gear of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable valve gear of an internal combustion engine in which its structure and operation method are simplified.SOLUTION: A cam carrier 4 is movable between a first position and a second position, and a guide groove 43 is formed on the cam carrier 4. In the guide groove 43, one of a pair of side wall surfaces facing each other is a first switching cam 43A for moving the cam carrier 4 to the first position and the other is a second switching cam 43B for moving the cam carrier 4 to the second position. First switching pin 51 and second switching pin 52 which can be inserted into the guide groove 43 and can reciprocate in the radial direction of a camshaft 3 are arranged in parallel along the axial direction of the camshaft 3. The first switching pin 51 can come into contact with the first switching cam 43A, and the second switching pin 52 can come into contact with the second switching cam 43B. The first switching pin 51 and second switching pin 52 are coupled by a coupling mechanism 57 for moving them oppositely each other along the radial direction of the camshaft 3.

Description

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

  Conventionally, as a variable valve operating apparatus for an internal combustion engine, a variable valve operating apparatus 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 is known. (For example, refer to Patent Document 1). In this variable valve operating apparatus, a switching pin provided on an operating member so as to be reciprocally movable in the radial direction of the cam carrier is inserted into and removed from a spiral guide groove formed on the outer periphery of the cam carrier, whereby the cam carrier is pivoted. It is designed to move in the direction.

Japanese Patent No. 430618

  However, in the conventional variable valve system described above, in order to reciprocate the cam carrier, it is necessary to form two switching pins and separate guide grooves for these switching pins, which complicates the structure of the cam switching mechanism. was there. In the above variable valve operating apparatus, it is difficult to process a spiral guide groove having a narrow groove width on the outer periphery of the cam carrier.

  The present invention has been made in view of the above-described problems, and is a variable valve operating apparatus for an internal combustion engine that changes a valve operating characteristic by moving a cam carrier having a plurality of cams in the axial direction of the cam shaft. An object of the present invention is to simplify the structure and operating method of the cam switching mechanism.

  In order to solve the above-described problems and achieve the object, an aspect of the present invention is provided with a cam shaft rotatably supported on the cylinder head side, and provided so as to be coaxial with the cam shaft. An internal combustion engine, and a cam carrier that is arranged so that a plurality of cams that are rotated integrally with each other and movable in the axial direction of the cam shaft and that have different valve operating characteristics on the outer peripheral surface are adjacent to each other In the variable valve operating apparatus for an internal combustion engine, the plurality of cams are arranged on the main body side and include a cam switching unit that switches a cam that moves the cam carrier in the axial direction of the cam shaft to operate the valve. A cam and a second cam, and the cam carrier is movable between a first position where the valve is actuated by the first cam and a second position where the valve is actuated by the second cam. A guide groove is formed so as to go around the carrier, and one of the pair of side wall surfaces facing each other is a first switching cam that moves the cam carrier to the first position. The other is a second switching cam that moves the cam carrier to the second position. The first switching pin and the second switching pin that can be inserted into the guide groove and can be reciprocated in the radial direction of the cam shaft are cam shafts. The first switching pin can contact the first switching cam, the second switching pin can contact the second switching cam, the first switching pin and the second switching pin. The pins are connected by a connecting mechanism that moves the pins in opposite directions along the radial direction of the cam shaft.

  As a said aspect, a connection mechanism has the 1st rack formed in the side surface of the 1st switching pin, the 2nd rack formed in the 2nd switching pin facing the 1st rack, the 1st rack, and the 2nd rack And a gear that meshes with each other at the same time.

  In the above aspect, the first switching pin has a first recess formed on a side surface along a direction in which the first switching pin reciprocates, and a first rack is formed on the bottom surface of the first recess. The pin has a second recess formed on a side surface along a direction in which the second switching pin reciprocates, a second rack is formed on the bottom surface of the second recess, and each of the first recess and the second recess Both ends in the reciprocating direction are preferably formed with side walls that contact the gears and restrict the movement range of the first switching pin and the second switching pin.

  As described above, the guide groove has a maximum groove width portion where the groove width is maximum, a minimum groove width portion where the groove width is minimum, and a groove width which communicates between the maximum groove width portion and the minimum groove width portion. The minimum groove width portion is a groove width through which one of the first switching pin and the second switching pin can pass, and the maximum groove width portion is a groove width direction centering on the minimum groove width portion. It is preferable that the groove width has a space through which one of the first switching pin and the second switching pin can pass.

  In the above aspect, the second cam may be a pause cam that pauses the valve. Thus, the stop cam that stops the valve is a cam that has a lift amount of zero.

  As the above aspect, when a driving force for moving the first switching pin or the second switching pin in the axial direction is applied to one of the first switching pin or the second switching pin and the driving force is removed, It is preferable to provide a spring that forcibly moves the first switching pin toward the guide groove.

  According to the variable valve operating apparatus for an internal combustion engine according to the present invention, the structure and operating method of the mechanism for switching the cam can be simplified.

FIG. 1 is a 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 an exploded perspective view of the variable valve operating apparatus for an 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 cross-sectional view showing a state in which a hole for inserting the first switching pin in the variable valve apparatus for the internal combustion engine according to the embodiment of the present invention is cut in the axial direction. 5 is a cross-sectional view taken along the line VV in FIG. FIG. 6 is a cross-sectional view showing a state in which a hole for inserting the second switching pin in the variable valve operating apparatus for an internal combustion engine according to the embodiment of the present invention is cut in the axial direction. 7 is a sectional view taken along line VII-VII in FIG. FIG. 8 is an exploded perspective view showing a connection mechanism mounting method in the variable valve operating apparatus for an internal combustion engine according to the embodiment of the present invention. FIG. 9-1 is a perspective view showing a state in which the cam carrier in the variable valve operating apparatus for an internal combustion engine according to the embodiment of the present invention is arranged at a first position (a position where a high-speed cam is selected). FIG. 9-2 is a perspective view illustrating a state during a switching operation between the first switching pin and the second switching pin in the variable valve operating apparatus for the internal combustion engine according to the embodiment of the present invention. FIG. 9-3 is a perspective view showing a state in which the cam carrier in the variable valve operating apparatus for the internal combustion engine according to the embodiment of the present invention starts moving toward the second position (position where the low speed cam is selected). FIG. 9-4 is a perspective view showing a state where the cam carrier in the variable valve operating apparatus for an internal combustion engine according to the embodiment of the present invention is arranged at the second position (position where the low-speed cam is selected). FIG. 10 is a perspective view of the cam carrier when the second cam in the variable valve operating apparatus for an internal combustion engine according to another embodiment of the present invention is a pause cam.

  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 known cylinder head, and includes a head main body 1A and a head cover 1B. As shown in FIG. 2, the variable valve apparatus 2 includes a cam shaft 3, a cam carrier 4, and a cam switching unit 5 disposed above the cam carrier 4, and changes the lift state of the intake valve 13. In order to achieve this, the cam is switched. 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.

(Rocker arm)
As shown in FIGS. 1 and 2, in the present embodiment, a rocker arm 11 of a type that swings as the cam carrier 4 rotates is used. The rocker arm 11 is disposed such that a recess formed on the lower surface of the one end portion 11 </ b> C abuts on a pivot 12 </ b> A of a hydraulic lash adjuster (HLA) 12. 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 high speed cam 41 or the low 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. The intake valve 13 is provided so as to be able to advance and retreat in the axial direction with respect to the cylinder head 1 and is urged by a valve spring 14 in a direction of pulling up (a direction of closing the intake port and the combustion chamber).

(Cam shaft)
As shown in FIG. 1, 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 upper portion of the head main body 1A. The camshaft 3 includes an interlocking portion so as to rotate in conjunction with a crankshaft (not shown) by a chain or belt (not shown). The lower cam housing 6 and the upper cam housing 7 are covered with a head cover 1B and are built in the cylinder head 1. The rotational speed of the camshaft 3 is set to be 1/2 of the rotational speed of the crankshaft. In the present embodiment, the camshaft 3 is arranged so as to extend along the front-rear direction of the engine as the internal combustion engine (the direction indicated by the arrow in FIG. 2). As shown in FIG. 2, 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 camshaft 3.

  As shown in FIGS. 2, 4, and 5, a positioning mechanism 32 is provided in a region near the axial direction of the region where the spline external teeth 31 are formed on the camshaft 3. The positioning mechanism 32 is housed in the housing recess 33 formed in a recess in the radial direction with respect to the cam shaft 3, a spring 34 housed in the housing recess 33, and the housing recess 33. And a ball 35 disposed so as to partially protrude from the surface of the cam shaft 3. As shown in FIG. 5, the ball 35 is locked to a first position positioning groove 46 and a second position positioning groove 47 provided on the cam carrier 4 side described later.

(Cam carrier)
As shown in FIGS. 2 and 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.

  Further, a first position positioning groove 46 and a second position positioning groove 47 are formed in a region adjacent to the region where the spline inner teeth 45 are formed on the inner peripheral surface of the cam carrier 4. . The first position positioning groove 46 and the second position positioning groove 47 engage the cam carrier 4 with the first position and the second position when the ball 35 of the positioning mechanism 32 provided on the cam shaft 3 side is locked. Position between the positions by clicking.

  As shown in FIGS. 2 and 3, the cam carrier 4 includes a high-speed cam 41 as a first cam and a low-speed cam 42 as a second cam, which are different in valve operation characteristics on the peripheral surface, and are integrated in an axial direction. Is provided. In addition, the one-piece | unit structure of the high speed cam 41 and the low speed cam 42 is arrange | positioned at predetermined intervals. When a pair of high-speed cams 41 and 41 is selected, each high-speed cam 41 is positioned above the rocker arm 11, and when a pair of low-speed cams 42 is selected, each low-speed cam 42 is connected to the rocker arm 11. It is located above. 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 10 are set to be the same. The cam carrier 4 is movable between a first position where the intake valve 13 is operated by the high speed cam 41 and a second position where the intake valve 13 is operated by the low speed cam 42.

  As shown in FIG. 3, 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 is more radially outward than the nose portion 41B of the high-speed cam 41 toward the radially outer side from the base circle portion 42A. A nose portion 42B formed with a low projecting dimension. As shown in FIG. 3, the high-speed cam 41 and the low-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 high-speed cam 41 and the low-speed cam 42 are arranged in a direction having substantially the same phase. The high-speed cam 41 and the low-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.

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

  As shown in FIG. 3, the guide groove 43 includes a maximum groove width portion 43C having a maximum groove width, a minimum groove width portion 43D having a minimum groove width, a maximum groove width portion 43C, and a minimum groove width portion 43D. A groove width changing portion 43E communicating between the two. The minimum groove width portion 43D is a groove width through which one of a first switching pin 51 and a second switching pin 52 described later can pass. The maximum groove width portion 43C is formed to have a groove width in which one of the first switching pin 51 and the second switching pin 52 has a space that allows passage through the outer sides in the groove width direction around the minimum groove width portion 43D. .

(Cam switching part)
As shown in FIG. 2, the cam switching unit 5 includes a first switching pin 51, a second switching pin 52, a gear 53, and a spring that biases the first switching pin 51 in a direction protruding from the lower surface of the head cover 1B. 54 and plugs 55A, 55B, and 56 (see FIG. 8). As shown in FIGS. 4 and 6, the first switching pin 51 and the second switching pin 52 can reciprocate in the radial direction of the cam shaft 3 with respect to the head cover 1 </ b> B and can be inserted into the guide groove 43. Placed in position. The first switching pin 51 and the second switching pin 52 are arranged in parallel along the axial direction of the camshaft 3. The first switching pin 51 can contact the first switching cam 43A in a protruding state, and the second switching pin 52 can contact the second switching cam 43B in a protruding state. Further, the first switching pin 51 and the second switching pin 52 are connected by a connecting mechanism 57 that moves in the opposite directions along the radial direction of the camshaft 3.

  The coupling mechanism 57 includes a first rack 51B formed on the side surface of the first switching pin 51, a second rack 52B formed on the second switching pin 52 facing the first rack 51B, and the first rack 51B. A gear 53 that meshes with the second rack 52B at the same time. As shown in FIG. 5, the first rack 51 </ b> B is formed on the bottom surface of the first recess 51 </ b> A formed on the side surface along the direction in which the first switching pin 51 reciprocates. The second rack 51B is formed on the bottom surface of the second recess 52A formed on the side surface along the direction in which the second switching pin 52 performs the reciprocating operation. As shown in FIG. 5, side walls 51 </ b> C and 51 </ b> C are formed at both ends of the first recess 51 </ b> A in the reciprocating direction so as to contact the gear 53 and restrict the moving range of the first switching pin 51. Side walls 52 </ b> C that abut the gear 53 and restrict the movement range of the second switching pin 52 are formed at both ends of the second recess 52 </ b> A in the reciprocating direction.

  As shown in FIG. 8, the first switching pin 51 is inserted in the first pin hole 58A provided so as to penetrate the head cover 1B so as to be slidable in the axial direction. The second switching pin 52 is inserted in a second pin hole 58B provided so as to penetrate the head cover 1B so as to be slidable in the axial direction. The first pin hole 58A and the second pin hole 58B are set to be substantially parallel. As shown in FIG. 8, the first pin hole 58A and the second pin hole 58B communicate with each other in the gear arrangement space 58C at an intermediate position in the axial direction. In the head cover 1B, a gear insertion port 59 is formed so as to communicate with the gear arrangement space 58C from the side of the gear arrangement space 58C (in a direction orthogonal to the first pin hole 58A and the second pin hole 58B).

  As shown in FIG. 8, the first switching pin 51 is inserted into the first pin hole 58A. The second switching pin 52 is inserted into the second pin hole 58B. The first pin hole 58A is closed by a plug 55A with the spring 54 inserted on the first switching pin 51. The second pin hole 58B is closed by the plug 55B with the second switching pin 52 inserted. A gear 53 is inserted into a gear arrangement space 58C from a gear insertion port 59 formed on the side surface of the head cover 1B. The gear 53 is disposed between the first rack 51B of the first switching pin 51 and the second rack 52B of the second switching pin 52 so as to mesh with each other. As shown in FIG. 7, in the gear 53, the gear shaft portion 53 </ b> A is rotatably supported by a bearing portion 58 </ b> D provided on the head cover 1 </ b> B side and a bearing portion 56 </ b> A provided on the plug 56.

  As shown in FIG. 4, the head cover 1B is formed with a first oil passage 60 communicating with the upper portion of the first pin hole 58A. The first oil passage 60 communicates with an oil gallery 61 formed in the head cover 1B. As shown in FIG. 6, the head cover 1B is formed with a second oil passage 62 communicating with the upper portion of the second pin hole 58B. The second oil passage 62 communicates with an oil gallery 63 formed in the head cover 1B. These oil galleries 61 and 63 are formed so as to communicate with an oil pump (not shown). These oil galleries 61 and 63 can be switched so that hydraulic pressure is supplied to either one by a hydraulic switching mechanism (not shown) using, for example, an electromagnetic valve. For this reason, as shown in FIG. 5, the first switching pin 51 and the second switching pin 52 protrude from the lower surface of the head cover 1 </ b> B by the operation of the coupling mechanism 57.

(Operation and operation of variable valve system)
Hereinafter, the switching operation to the high speed cam 41 and the low speed cam 42 of the variable valve operating apparatus 2 according to the present embodiment will be described.

  FIG. 9A shows a state where the high speed cam 41 is selected and operated in the variable valve operating apparatus 2. The position of the cam carrier 4 in such a state is defined as a first position. In this state, the base circle portion 41A of the high-speed cam 41 and the pressed roller 11A of the rocker arm 11 are in contact with each other. At this time, the first switching pin 51 is arranged so as to pass through the minimum groove width portion 43D of the guide groove 43 as shown in FIG. At this time, the ball 35 provided on the cam shaft 3 side is engaged with the first position positioning groove 46 on the cam carrier 4 side.

  When switching from the state in which the high speed cam 41 is selected to the state in which the low speed cam 42 is selected (the cam carrier 4 is in the second position) as shown in FIG. 9B, the second switching pin 52 is guided. It protrudes from the head cover 1B side so as to be inserted into the groove 43. In order to project the second switching pin 52, hydraulic pressure is applied from the oil gallery 63 to the second pin hole 58B through the second oil passage 62 by a hydraulic switching mechanism (not shown). Accordingly, the second switching pin 52 is driven in a direction protruding toward the guide groove 43. When the second switching pin 52 projects, the first switching pin 51 retracts from the guide groove 43 toward the head cover 1B as the gear 53 rotates, as shown in FIG.

  As shown in FIG. 9-2, the second switching pin 52 is inserted into the guide groove 43. Then, the cam carrier 4 moves the cam carrier 4 to the second position through the state shown in FIG. 9-3 by the action of the second switching cam 34B that contacts the second switching pin 52. At this time, the base circle portion 41A of the high-speed cam 41 and the base circle portion 42A of the low-speed cam 42 slide smoothly with respect to the pressed roller 11A of the rocker arm 11, and as shown in FIG. Thus, the base circle portion 42A of the low speed cam 42 is in contact.

  When the cam carrier 4 is displaced with respect to the cam shaft 3 in this way, the ball 35 on the cam shaft 3 side disengages from the first position positioning groove 46 shown in FIG. 5 and moves to the second position positioning groove 47. And become engaged. As a result, the cam carrier 4 is fixed at the position (second position) where the low-speed cam 42 is selected with respect to the cam shaft 3. Thus, when the low speed cam 42 is selected and the cam carrier 4 is in the second position, the second switching pin 52 is the minimum groove of the guide groove 43 until the switching to the high speed cam 41 is performed. The arrangement is such that it passes through the width portion 43D.

  On the other hand, when switching from the low speed cam 42 to the high speed cam 41, as shown in FIG. 4, the first switching is performed by applying hydraulic pressure from the oil gallery 61 to the upper portion of the first pin hole 58A via the first oil passage 60. The pin 51 is protruded from the lower surface of the head cover 1B. The gear 53 rotates with the movement of the first rack 51 </ b> B of the first switching pin 51. Accordingly, the second rack 52B moves in the opposite direction to the first rack 51B. In other words, the second switching pin 52 performs an operation in the retracting direction with respect to the lower surface of the head cover 1B. Then, when the first switching cam 43A of the guide groove 43 is in contact with the first switching pin 51, the cam carrier 4 moves to the first position shown in FIG. The cam that contacts the pressed roller 11 </ b> A is switched from the low speed cam 42 to the high speed cam 41.

  As shown in FIG. 5, in the present embodiment, side walls 51C, 51C, 52C are provided at both ends of the first recess 51A of the first switching pin 51 and the second recess 52A of the second switching pin 52 in the reciprocating direction. 52C is formed. These side walls 51 </ b> C and 52 </ b> C contact the gear 53 and serve as a stopper that restricts the movement range of the first switching pin 51 and the second switching pin 52.

  In the present embodiment, the mechanism for switching between the high-speed cam 41 and the low-speed cam 42 can be brought into contact with the first switching cam 43A and the single guide groove 43 having the first switching cam 43A and the second switching cam 43B as side walls. The first switching pin 51 and the second switching pin 52 that can come into contact with the second switching cam 43B can be used. That is, it is not necessary to form guide grooves individually for the first switching pin 51 and the second switching pin 52. For this reason, in the variable valve operating apparatus 2 according to the present embodiment, the mechanism for switching the cam can have a simple structure.

  In the present embodiment, since the first switching pin 51 and the second switching pin 52 are coupled by the coupling mechanism 57 that moves in the opposite directions to each other, the first switching pin 51 and the second switching pin 52 are simultaneously formed due to the mechanical structure. Contact with the first switching cam 43A and the second switching cam 43B can be prevented, and the operation method of the switching pin can be simplified. Therefore, in the variable valve operating apparatus 2 according to the present embodiment, the structure and operating method of the mechanism for switching the cam can be simplified.

  In the present embodiment, since the coupling mechanism 57 is configured by the two racks of the first rack 51B and the second rack 52B and the gear 53, the first switching pin 51 and the second switching pin 52 are reliably connected to each other. While being able to move to a reverse direction, the structure of a connection mechanism can be simplified. In addition, in the present embodiment, since both ends in the moving direction of the first recess 51A and the second recess 52A are the side walls 51C and 52C that restrict the moving range of the first switching pin 51 and the second switching pin 52, the cam The structure of the mechanism for switching between can be simplified.

  In the present embodiment, the maximum groove width portion 43C of the cam carrier 4 is centered on the minimum groove width portion 43D on both outer sides (both outer sides in the axial direction of the cam carrier 4). A groove width having a space through which one of the pins 52 can pass is formed. For this reason, when the cam carrier 4 is in the first position, the first switching pin 51 is in a position passing through the minimum groove width portion 43 </ b> D of the guide groove 43 in the axial direction of the cam shaft 3. At this time, before or after the first switching pin 51 passes through the minimum groove width portion 43D, the second switching pin 52 can be inserted into the maximum groove width portion 43C. Here, if the second switching pin 52 is inserted into the guide groove 43 at a position corresponding to the maximum groove width portion 43C, the cam carrier 4 is moved from the first position to the second position by the operation described below. Can do. That is, the second switching pin 52 moves from the maximum groove width portion 43C to the groove width changing portion 43E by the rotation of the cam carrier 4, and the cam carrier 4 moves to the second position by contacting the groove width changing portion 43E. Start. When the second switching pin 52 reaches the minimum groove width portion 43D, the movement of the cam carrier 4 to the second position is completed. At this time, the cam carrier 4 does not return to the first position without retracting the second switching pin 52 from the guide groove 43. When the cam carrier 4 is in the second position, if the first switching pin 51 is inserted into the guide groove 43 at a position corresponding to the maximum groove width portion 43C, the second switching pin 52 is changed to the groove width changing portion 43E. The cam carrier 4 can be moved to the first position. At this time, the cam carrier 4 does not return to the second position without retracting the first switching pin 51 from the guide groove 43. Therefore, it is not necessary to retract the first switching pin 51 and the second switching pin 52 from the guide groove 43 when the movement of the cam carrier 4 is completed, so that the switching pin operating method can be simplified.

  In the present embodiment, the cam carrier 4 is moved in the axial direction in a configuration including a single guide groove 43 and a pair of first switching pin 51 and second switching pin 52, and the low-speed cam 42 and the high-speed cam 41 It is set as the structure which switches. In the conventional variable valve operating apparatus, the piston is moved in and out of a groove formed in a spiral shape on the outer peripheral surface of the cam carrier using a plunger that reciprocates in the radial direction of the cam carrier 4. Using such a plunger goes against the miniaturization of the device. Since the variable valve apparatus 2 according to the present embodiment does not require such a plunger, it is possible to suppress an increase in the height of the cylinder head 1. In addition, with this configuration, in the present embodiment, the total length of the cam carrier 4 in the axial direction can be shortened, and the variable valve apparatus 2 can be downsized.

  According to the variable valve operating apparatus 2 according to the present embodiment, when the base circular portions 41A and 42A are in contact with the pressed roller 11A of the rocker arm 11, the cam carrier 4 is moved to move the high speed cam 41 and the low speed cam 42. Therefore, the cam can be switched smoothly.

  According to the variable valve operating apparatus 2 according to the present embodiment, the ball 35, the first position positioning groove 46, and the second position so that the cam carrier 4 is positioned with respect to the cam shaft 3 by a click operation. The positioning groove 47 is used. For this reason, according to this embodiment, the cam carrier 4 can be positioned reliably.

(Other embodiments)
Although the embodiment has been described above, the present invention is not limited to this. For example, in the above-described embodiment, the first switching pin 51 and the second switching pin 52 are moved in a staggered direction by the rack and pinion mechanism using the first rack 51B and the second rack 52B with the gear 53 interposed therebetween. Although realized, the present invention is not limited to this, and it is of course possible to use other mechanisms for performing a seesaw operation.

  In the above embodiment, the present invention is applied to the two-stage variable valve device of the high speed cam 41 and the low speed cam 42. However, the lift amount of the second cam is 0 as in the cam carrier 4A shown in FIG. If the stop cam 48 has a peripheral surface, a valve stop function can be realized. With this configuration, the structure and operating method of the mechanism for switching the cam can be simplified, and the valve can be stopped.

Moreover, in said embodiment, although it is a structure provided with the two systems oil gallery 61 and 63, it is good also as a structure which strengthened the spring 54 and abbreviate | omitted one system oil gallery. That is, an oil gallery is connected to one of the first switching pin 51 or the second switching pin 52, and the first switching pin 51 or the second switching pin 52 is moved in the axial direction by a driving force applied from the oil gallery. When the driving force is removed, the first switching pin 51 may be forcibly moved toward the guide groove 43 by the spring 54. In this case, when the oil gallery 63 is connected to the second switching pin 52, and the driving force (oil pressure) applied to the second switching pin 52 is removed from the oil gallery 63, the first switching pin 51 is moved by the spring 54. It moves to the guide groove 43 side. As a result, the cam carrier 4 can be moved to the first position, and the valve pause can be released.

DESCRIPTION OF SYMBOLS 1 Cylinder head 1B Head cover 2 Variable valve apparatus 3 Cam shaft 4, 4A Cam carrier 5 Cam switching part 6 Lower cam housing 7 Upper cam housing 11 Rocker arm 11A Pressed roller 13 Intake valve 31 Spline external tooth 41 High speed cam 42 Low speed cam 43 Guide groove 43A 1st switching cam 43B 2nd switching cam 43C Maximum part groove width 43D Minimum groove width part 43E Groove width change part 45 Spline internal teeth 48 Pause cam 51 First switching pin 51A First recess 51B First rack 51C Side wall 52 Second switching pin 52A Second recess 52C Side wall 53 Gear 53A Gear shaft portion 54 Spring 55A, 55B, 56 Plug 56A Bearing portion 57 Connection mechanism 58A First pin hole 58B Second pin hole 58C Gear arrangement space 58D Bearing portion 59 Gear insertion Mouth 60 No. 1 Le passage 61 oil gallery 62 second oil passage 63 the oil gallery

Claims (6)

A cam shaft rotatably supported on the cylinder head side is provided so as to be coaxial with the cam shaft, and rotates integrally with the cam shaft and is movable in the axial direction of the cam shaft. A cam carrier having a plurality of cams formed on the outer peripheral surface so as to have different valve operating characteristics arranged adjacent to each other, an internal combustion engine body side, and the cam carrier as an axis of the camshaft. A variable valve operating apparatus for an internal combustion engine, comprising: a cam switching unit that switches the cam that moves in a direction to operate the valve;
The plurality of cams are a first cam and a second cam,
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 guide groove is formed on the outer peripheral surface of the cam carrier so as to go around the cam carrier,
The guide groove is a first switching cam in which one of the pair of side wall surfaces facing each other moves the cam carrier to the first position, and the other of the pair of side walls moves the cam carrier to the cam carrier. A second switching cam for moving to the second position;
A first switching pin and a second switching pin that can be inserted into the guide groove and can reciprocate in the radial direction of the cam shaft are arranged in parallel along the axial direction of the cam shaft,
The first switching pin can be in contact with the first switching cam, the second switching pin can be in contact with the second switching cam,
A variable valve operating apparatus for an internal combustion engine, wherein the first switching pin and the second switching pin are connected by a connecting mechanism that moves the cam shaft in opposite directions along a radial direction of the cam shaft. The coupling mechanism is
A first rack formed on a side surface of the first switching pin;
A second rack formed on the second switching pin facing the first rack;
A gear that meshes simultaneously with the first rack and the second rack;
The variable valve operating apparatus for an internal combustion engine according to claim 1, comprising: The first switching pin has a first recess formed on a side surface along a direction in which the first switching pin reciprocates, and the first rack is formed on a bottom surface of the first recess.
The second switching pin has a second recess formed on a side surface along a direction in which the second switching pin reciprocates, and the second rack is formed on a bottom surface of the second recess.
Both ends of the first recess and the second recess in the reciprocating direction are formed with side walls that abut against the gear and restrict the movement range of the first switching pin and the second switching pin. The variable valve operating apparatus for an internal combustion engine according to claim 2. The guide groove includes a maximum groove width portion where the groove width is maximum, a minimum groove width portion where the groove width is minimum, and a groove width change portion which connects between the maximum groove width portion and the minimum groove width portion. And comprising
The minimum groove width portion is a groove width through which one of the first switching pin and the second switching pin can pass,
The maximum groove width portion is formed to have a groove width having a space through which one of the first switching pin and the second switching pin can pass on both outer sides in the groove width direction around the minimum groove width portion. The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein: The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 4, wherein the second cam is a pause cam that pauses the valve. When the driving force for moving the first switching pin or the second switching pin in the axial direction is applied to one of the first switching pin or the second switching pin and the driving force is removed, The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 5, further comprising a spring that forcibly moves one switching pin toward the guide groove.

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