JP2016017451A - 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 capable of preventing two switching pins from strongly interfering with a pair of sidewalls of a guide groove of a cam carrier while simplifying a mechanism for switching a cam, and capable of enhancing reliability of a variable valve gear mechanism.SOLUTION: When one of a first switching pin 51 and a second switching pin 52 is inserted in a guide groove 43, an insertion direction end of the other is always positioned on a radial outer side of a camshaft 3 than an outer peripheral surface 4A of a cam carrier 4, and forms a space s between itself and the outer peripheral surface 4A of the cam carrier 4. An insertion direction end 51D of the first switching pin 51 and an insertion direction end 52D of the second switching pin 52 are set to always pass by each other on the radial outer side of the camshaft 3 than the outer peripheral surface 4A of the cam carrier 4. A reciprocating stroke L1 of the first switching pin 51 and the second switching pin 52 is set twice or more a distance L2 from the outer peripheral surface 4A of the cam carrier 4 to a bottom surface 43G of the guide groove 43.SELECTED DRAWING: Figure 5

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. (See Patent Document 1). In this variable valve operating device, one of two switching pins provided on the operating member so as to be able to reciprocate 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. The cam carrier is moved in the axial direction.

Japanese Patent No. 4330618

  However, in the conventional variable valve operating apparatus, since the cam carrier is reciprocated, it is necessary to individually form guide grooves for the two switching pins, and there is a problem that the mechanism for switching the cam is complicated. 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.

  Further, in the conventional variable valve operating system for an internal combustion engine, when a single guide groove is formed on the cam carrier for the two switching pins, the two switching pins are driven by individual actuators, respectively. There is a possibility that two switching pins may be simultaneously inserted into the guide groove due to malfunction.

  Specifically, if the other switching pin is inserted into the guide groove before the one switching pin is removed from the guide groove, the two switching pins are simultaneously inserted into the guide groove. There is a possibility that the pin strongly interferes with the pair of side walls of the guide groove of the cam carrier.

  The present invention has been made paying attention to the above-mentioned problems, and while simplifying the cam switching mechanism, prevents the two switching pins from strongly interfering with the pair of side walls of the guide groove of the cam carrier. Then, it aims at providing the variable valve apparatus of the internal combustion engine which can improve the reliability of a variable valve mechanism.

  According to a first aspect of the present invention, a cam shaft rotatably supported by a cylinder head is provided so as to be coaxial with the cam shaft, and rotates integrally with the cam shaft, A plurality of cams which are movable in the axial direction and are arranged on the outer peripheral surface so that the operation characteristics of the valves are different from each other, and are arranged so as to be adjacent to each other. In the variable valve operating apparatus for an internal combustion engine 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, and the cam carrier is the valve by the first cam. The guide groove is formed on the outer peripheral surface of the cam carrier so as to circulate around the cam carrier. In the guide groove, one of the pair of side walls facing each other is a first switching cam that moves the cam carrier to the first position, and the other one of the pair of side walls is the cam carrier. A first switching pin that is a second switching cam that moves to the second position, can be inserted into the guide groove, and can be reciprocated in the radial 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, and the first switching pin can be contacted with the first switching pin. The second switching pin is connected by a connecting mechanism that moves the second switching pin in opposite directions along the radial direction of the cam shaft, and one of the first switching pin or the second switching pin is inserted into the guide groove. When said The distal end of the other switching direction of the one switching pin or the second switching pin is always located radially outside the cam shaft with respect to the outer peripheral surface of the cam carrier and between the outer peripheral surface of the cam carrier. A gap is formed.

  As a second aspect of the present invention, the insertion direction front end portion of the first switching pin and the insertion direction front end portion of the second switching pin are always on the radially outer side of the cam shaft from the outer peripheral surface of the cam carrier. It is preferable that they are set so as to pass each other.

  As a third aspect of the present invention, the reciprocating stroke of the first switching pin and the second switching pin is set to be twice or more the distance from the outer peripheral surface of the cam carrier to the bottom surface of the guide groove. preferable.

  Thus, according to said 1st aspect, the mechanism which switches a 1st cam and a 2nd cam, the single guide groove which uses a 1st switching cam and a 2nd switching cam as a pair of side wall, and a 1st switching cam The first switching pin that can come into contact with the second switching pin and the second switching pin that can come into contact with the second switching cam, and it is not necessary to individually form a guide groove in each of the first switching pin and the second switching pin. Can be simplified.

  Further, since the first switching pin and the second switching pin are switched to the first cam or the second cam by moving the first switching pin and the second switching pin in opposite directions to each other, the mechanism for switching the cam can be simplified.

  Further, when one of the first switching pin or the second switching pin is inserted into the guide groove, the other insertion direction front end of the first switching pin or the second switching pin is always more than the outer peripheral surface of the cam carrier. A gap is formed between the cam shaft and the outer peripheral surface of the cam carrier.

  Thereby, it can prevent that a 1st switching pin and a 2nd switching pin are simultaneously inserted in the guide groove of a cam carrier, and contact with a pair of side wall of a guide groove.

  As a result, it is possible to improve the reliability of the variable valve mechanism by simplifying the mechanism for switching the cam and preventing the two switching pins from strongly interfering with the pair of side walls of the guide groove of the cam carrier.

  According to said 2nd aspect, when the 1st switching pin and the 2nd switching pin reciprocate to the radial direction of a cam shaft, the insertion direction front-end | tip part of a 1st switching pin and the insertion direction front-end | tip part of a 2nd switching pin Can be positioned at the same height outside the cam carrier in the radial direction of the cam shaft.

  For this reason, via the state where the insertion direction front end portion of the first switching pin and the insertion direction front end portion of the second switching pin are located at the same height outside the cam carrier in the radial direction of the cam shaft, One of the first switching pin or the second switching pin is inserted into the guide groove of the cam carrier.

  Therefore, since it can prevent that the front-end | tip part of a 1st switching pin and the front-end | tip part of a 2nd switching pin are located in a guide groove simultaneously, two switching pins strongly interfere with a pair of side wall of the guide groove of a cam carrier. Can be prevented.

  According to said 3rd aspect, the intermediate position of the stroke which is a passing position of a 1st switching pin and a 2nd switching pin can be located in the radial direction outer side of a cam shaft rather than the outer peripheral surface of a cam carrier.

  Therefore, the first switching pin and the second switching pin can be reliably set so as to pass in the reciprocating direction on the outer side in the radial direction of the cam shaft from the outer peripheral surface of the cam carrier.

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 the internal combustion engine according to the embodiment of the present invention. FIG. 3 is a perspective view showing a cam carrier in the variable valve operating apparatus for an internal combustion engine according to the embodiment of the present invention. FIG. 4 is a cross-sectional view showing a state in which a hole for inserting the first switching pin in the variable valve operating 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. 6A is a perspective view illustrating 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 has moved to a first position (a position where a high-speed cam is selected). FIG. 6-2 is a perspective view showing a state when the first switching pin and the second switching pin pass each other in the variable valve operating apparatus for the internal combustion engine according to the embodiment of the present invention. FIG. 6-3 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. 6-4 is a perspective view showing a state where the cam carrier in the variable valve operating apparatus for the internal combustion engine according to the embodiment of the present invention has moved to the second position (position where the low-speed cam is selected).

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 cylinder head 1 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 this 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).
(Camshaft)

  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 cam shaft 3 is disposed 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 in a first position positioning groove 46 or a second position positioning groove 47 formed in the cam carrier 4 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 are configured so that the ball 35 of the positioning mechanism 32 provided on the cam shaft 3 side is locked, whereby the cam carrier 4 is shown in FIG. Positioning is performed between the first position A and the second position B shown in FIG.

  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 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 above the rocker arm 11. Located in.

  That is, the interval between the high-speed cams 41, the interval between the low-speed cams 42, and the interval between the intake valves 13 are set to be the same. The cam carrier 4 has a first position A shown in FIG. 6A where the intake valve 13 is operated by the high speed cam 41, and a second position B shown in FIG. 6-4 where the intake valve 13 is operated by the low speed cam 42. Can be moved to.

  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.

  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 arrangement of the high-speed cam 41 and the low-speed cam 42 with respect to the camshaft 3 defines the lift timing of the intake valve 13 that operates in accordance with the operation of a crankshaft (not shown).

  2 and 3, a guide groove 43 is formed on the outer peripheral surface 4A of the cam carrier 4 so as to circulate and continue. In the guide groove 43, one of the pair of side walls facing each other is a first switching cam 43A that moves the cam carrier 4 to the first position A shown in FIG. The other side wall of the pair of side walls is a second switching cam 43B that moves the cam carrier 4 to the second position B shown in FIG. 6-4.

  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 spring 54 that urges the first switching pin 51 in a direction protruding from the lower surface of the head cover 1B, and a plug. 55A and 55B.

  Further, as shown in FIG. 4, the cam switching unit 5 includes a plug 56. The first switching pin 51 and the second switching pin 52 can be reciprocated in the radial direction of the cam shaft 3 with respect to the head cover 1B, and are disposed at positions where they can be inserted into the guide grooves 43.

  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.

  The cam switching unit 5 includes a coupling mechanism 57 that moves the first switching pin 51 and the second switching pin 52 in the opposite directions along the radial direction of the cam shaft 3. Yes.

  As shown in FIG. 2, the coupling mechanism 57 includes a first rack 51B formed on the side surface of the first switching pin 51 and a second rack 52B formed on the second switching pin 52 facing the first rack 51B. And a pinion gear 53 that meshes simultaneously with the first rack 51B and the second rack 52B.

  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 52B 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 reciprocates.

  Side ends 51 </ b> C and 51 </ b> C that abut the pinion gear 53 and restrict the movement range of the first switching pin 51 are formed at both ends of the first recess 51 </ b> A in the reciprocating direction. Side walls 52 </ b> C that abut the pinion 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.

  The head cover 1B is provided with a cylindrical switching pin accommodating portion 1C, and the first switching pin 51 and the second switching pin 52 are accommodated in the switching pin accommodating portion 1C. The switching pin accommodating portion 1C is formed so that the first pin hole 58A and the second pin hole 58B are parallel to each other so as to penetrate the switching pin accommodating portion 1C in the radial direction of the cam shaft 3.

  The first switching pin 51 is slidably inserted into the first pin hole 58A, and the second switching pin 52 is slidably inserted into the second pin hole 58B.

  The first pin hole 58A and the second pin hole 58B are communicated 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).

  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 pinion 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 pinion 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. 4, in the pinion 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.

  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.

  A second oil passage 62 is formed in the head cover 1B. The second oil passage 62 communicates with an oil gallery 63 formed in the head cover 1B and communicates with an upper portion of the second pin hole 58B.

  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. Therefore, as shown in FIG. 5, due to the operation of the coupling mechanism 57, either the first switching pin 51 or the second switching pin 52 protrudes from the lower surface of the switching pin accommodating portion 1C of the head cover 1B to the cam carrier 4 side. It is supposed to be.

  Here, in the present embodiment, in order to avoid the first switching pin 51 and the second switching pin 52 from being simultaneously sandwiched between the pair of side walls of the guide groove 43, as shown in FIG. The dimensions and relative positions of the second switching pin 52 and the guide groove 43 are set as follows.

  When one of the first switching pin 51 or the second switching pin 52 is inserted into the guide groove 43, the other insertion direction tip of the first switching pin 51 or the second switching pin 52 is always in the cam carrier 4. It is set so as to form a gap s between the outer peripheral surface 4 </ b> A and the outer peripheral surface 4 </ b> A of the cam carrier 4 while being positioned on the outer side in the radial direction of the cam shaft.

  That is, when the first switching pin 51 is inserted into the guide groove 43, the insertion direction front end 52 </ b> D of the second switching pin 52 is positioned on the outer side in the radial direction of the cam shaft 3 with respect to the outer peripheral surface 4 </ b> A of the cam carrier 4. In addition, a gap s is set between the second switching pin 52 and the outer peripheral surface 4A of the cam carrier 4. Similarly, when the second switching pin 52 is inserted into the guide groove 43, the insertion direction front end portion 51 </ b> D of the first switching pin 51 is located on the outer side in the radial direction of the cam shaft 3 with respect to the outer peripheral surface 4 </ b> A of the cam carrier 4. And a gap s is formed between the first switching pin 51 and the outer peripheral surface 4A of the cam carrier 4.

  Further, the insertion direction front end 51D of the first switching pin 51 and the insertion direction front end 52D of the second switching pin 52 are set so as to always pass each other on the outer side in the radial direction of the camshaft 3 with respect to the outer peripheral surface 4A of the cam carrier 4. ing. In other words, the passing position between the insertion direction front end portion 51D of the first switching pin 51 and the insertion direction front end portion 52D of the second switching pin 52 is located on the outer side in the radial direction of the cam shaft 3 from the outer peripheral surface 4A of the cam carrier 4. ing.

  Further, the reciprocating stroke L1 of the first switching pin 51 and the second switching pin 52 is set to be twice or more the distance L2 from the outer peripheral surface 4A of the cam carrier 4 to the bottom surface 43G of the guide groove 43.

  Further, in the radial direction of the cam shaft 3, the distance L 3 from the lower end of the switching pin accommodating portion 1 C that accommodates the first switching pin 51 and the second switching pin 52 to the outer circumferential surface 4 A of the cam carrier 4 is the outer circumference of the cam carrier 4. The distance L2 is set to be larger than the distance L2 from the surface 4A to the bottom surface 43G of the guide groove 43.

Note that the above settings regarding the dimensions and relative positions of the first switching pin 51, the second switching pin 52, and the guide groove 43 are performed in consideration of dimensional tolerances, assembly errors, thermal expansion, and the like of these members.
(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. 6A 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 A. 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 (a state in which the cam carrier 4 is in the second position B) as shown in FIG. The pin 52 is protruded from the head cover 1B side so as to be inserted into the guide 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 is projected, the first switching pin 51 is retracted from the guide groove 43 toward the head cover 1B as the pinion gear 53 rotates as shown in FIG.

  Thereafter, the second switching pin 52 is separated from the first switching pin 51 at a position where the first switching pin 51 comes out of the guide groove 43 and is separated from the outer peripheral surface 4A of the cam carrier 4 by the gap s in the outer peripheral direction of the cam shaft 3. After passing, it is inserted into the guide groove 43 as shown in FIG. 6-3. Thus, the first switching pin 51 and the second switching pin 52 are not inserted into the guide groove 43 at the same time.

  When the second switching pin 52 is inserted into the guide groove 43, the cam carrier 4 moves the cam carrier 4 to the second position B by the action of the second switching cam 34 </ b> B that contacts the second switching pin 52. At this time, the base circle 41A of the high-speed cam 41 and the base circle 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. 6-4, the pressed roller 11A. 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 to the cam shaft 3 at the position (second position B) where the low-speed cam 42 is selected.

  As described above, when the low speed cam 42 is selected and the cam carrier 4 is in the second position B, the second switching pin 52 is the minimum 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 groove 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 pinion gear 53 rotates with the movement of the first rack 51B 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 51 </ b> C and 52 </ b> C are formed at both ends of the first recess 51 </ b> A of the first switching pin 51 and the second recess 52 </ b> A of the second switching pin 52 in the reciprocating direction. Yes. These side walls 51 </ b> C and 52 </ b> C abut on the pinion gear 53 and serve as a stopper that restricts the movement range of the first switching pin 51 and the second switching pin 52.

  As described above, in the present embodiment, the mechanism for switching between the high speed cam 41 and the low speed cam 42 includes a single guide groove 43 having the first switching cam 43A and the second switching cam 43B as a pair of side walls, and the first The first switching pin 51 that can contact the switching cam 43A and the second switching pin 52 that can contact 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 apparatus 2 according to the present embodiment, the mechanism for switching the cam can be simplified.

  Further, since the first switching pin 51 and the second switching pin 52 are switched to the high speed cam 41 or the low speed cam 42 by moving the first switching pin 51 and the second switching pin 52 in opposite directions to each other, the mechanism for switching the cam is simplified. be able to.

  Also, when one of the first switching pin 51 or the second switching pin 52 is inserted into the guide groove 43, the other insertion direction front end of the first switching pin 51 or the second switching pin 52 is always the cam carrier. 4 is located on the outer side in the radial direction of the cam shaft 3 with respect to the outer peripheral surface 4 </ b> A, and a gap s is formed between the outer peripheral surface 4 </ b> A of the cam carrier 4.

  Thereby, it is possible to prevent the first switching pin 51 and the second switching pin 52 from being simultaneously inserted into the guide groove 43 of the cam carrier 4 and contacting the pair of side walls of the guide groove 43.

  As a result, while simplifying the mechanism for switching the cam, the first switching pin 51 and the second switching pin 52 are prevented from strongly interfering with the pair of side walls of the guide groove 43 of the cam carrier 4, so that the variable valve mechanism Reliability can be increased.

  In the present embodiment, the insertion direction front end portion 51D of the first switching pin 51 and the insertion direction front end portion 52D of the second switching pin 52 always pass each other on the outer side in the radial direction of the cam shaft 3 with respect to the outer peripheral surface 4A of the cam carrier 4. Is set to

  Thus, when the first switching pin 51 and the second switching pin 52 reciprocate in the radial direction of the camshaft 3, the distal end portion 51D of the first switching pin 51 and the distal end of the second switching pin 52 in the insertion direction are inserted. The portion 52D can be positioned at the same height on the radially outer side of the cam shaft 3 with respect to the outer peripheral surface 4A of the cam carrier 4.

  For this reason, the insertion direction front end portion 51D of the first switching pin 51 and the insertion direction front end portion 52D of the second switching pin 52 are positioned at the same height outside the outer peripheral surface 4A of the cam carrier 4 in the radial direction of the cam shaft 3. Through this state, one of the first switching pin 51 or the second switching pin 52 is inserted into the guide groove 43 of the cam carrier 4.

  Therefore, it is possible to prevent the insertion direction distal end portion 51D of the first switching pin 51 and the insertion direction distal end portion 52D of the second switching pin 52 from being simultaneously positioned in the guide groove 43, and thus the first switching pin 51 and the second switching pin 51 It is possible to prevent the pin 52 from strongly interfering with the pair of side walls of the guide groove 43 of the cam carrier 4.

  In the present embodiment, the reciprocating stroke L1 of the first switching pin 51 and the second switching pin 52 is set to be twice or more the distance L2 from the outer peripheral surface 4A of the cam carrier 4 to the bottom surface 43G of the guide groove 43. Yes.

  Thereby, the intermediate position of the stroke L <b> 1, which is the passing position between the first switching pin 51 and the second switching pin 52, can be positioned on the outer side in the radial direction of the cam shaft 3 with respect to the outer peripheral surface 4 </ b> A of the cam carrier 4.

Therefore, the first switching pin 51 and the second switching pin 52 can be reliably set so as to pass each other on the radially outer side of the cam shaft 3 with respect to the outer peripheral surface 4A of the cam carrier 4 in the reciprocating direction.
(Other embodiments)

  Although the embodiment has been described above, the present invention is not limited to this. For example, in the present embodiment, the movement of the first switching pin 51 and the second switching pin 52 moving in a staggered direction is realized by the coupling mechanism 57, but the present invention is not limited to this, and the first switching pin 51 and the second switching pin 52 are not limited to this. Of course, the first switching pin 51 and the second switching pin 52 can be moved in alternate directions.

  In the above embodiment, the present invention is applied to the two-stage variable valve operating device of the high speed cam 41 and the low speed cam 42. However, if the second cam is a rest cam having a peripheral surface with a lift amount of 0, the valve rest Functions are also feasible. With such a configuration, the structure and operating method of the mechanism for switching the cam can be simplified, and the valve can be stopped.

  In the above embodiment, the oil gallery 61, 63 of two systems is provided. However, the spring 54 may be reinforced to omit the oil gallery of one system. That is, the spring 54 connects the oil gallery to at least one of the first switching pin 51 and / or the second switching pin 52, and the first switching pin 51 and / or the second switching pin 52 is driven by the driving force applied from the oil gallery. A driving force for moving the shaft in the axial direction may be applied, and the first switching pin 51 may be forcibly moved to the guide groove 43 side by the spring 54 when the driving force is removed.

  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 ... Cam carrier, 5 ... Cam switching part, 41 ... High speed cam (1st cam), 42 ... Low speed cam (2nd cam) ), 43... Guide groove, 43 A... First switching cam (one or the other of the pair of side walls), 43 B... Second switching cam (one or the other of the pair of side walls), 51. Front end portion 52 ... second switching pin 52D ... insertion direction front end portion 57 ... connecting mechanism A ... first position B ... second position s ... clearance L1 ... stroke L2 ... distance

Claims (3)

A camshaft rotatably supported by the cylinder head, and provided so as to be coaxial with the camshaft, rotate integrally with the camshaft and move in the axial direction of the camshaft; 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, and operating the valve by moving the cam carrier in the axial direction of the cam shaft In the variable valve operating apparatus of the internal combustion engine for switching the cam to be
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,
In the guide groove, one of the pair of side walls facing each other is a first switching cam that moves the cam carrier to the first position, and the other of the pair of side walls moves the cam carrier to the first position. A second switching cam that moves 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,
The first switching pin and the second switching pin are coupled by a coupling mechanism that moves in the opposite directions along the radial direction of the cam shaft,
When one of the first switching pin or the second switching pin is inserted into the guide groove, the other insertion direction front end of the first switching pin or the second switching pin is always in the cam carrier. A variable valve operating apparatus for an internal combustion engine, wherein the variable valve operating apparatus is located outside the outer periphery in the radial direction of the cam shaft and has a gap with the outer peripheral surface of the cam carrier.   The insertion direction front end portion of the first switching pin and the insertion direction front end portion of the second switching pin are set so as to always pass each other on the outer side in the radial direction of the cam shaft from the outer peripheral surface of the cam carrier. The variable valve operating apparatus for an internal combustion engine according to claim 1.   The stroke of the reciprocating movement of the first switching pin and the second switching pin is set to be twice or more the distance from the outer peripheral surface of the cam carrier to the bottom surface of the guide groove. 3. A variable valve operating apparatus for an internal combustion engine according to 2.

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