JP2011085072A - Variable valve gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable valve gear achieving the simple movement/control of a cam and achieving the excellent combustion efficiency of an air-fuel mixture and the excellent durability of the cam. <P>SOLUTION: This variable valve gear 27 includes: a cylinder head 28; a plurality of intake valves 48 provided in the cylinder head 28; a camshaft 64 journalled to the cylinder head 28; the intake-side cam 65 rotated integrally with the camshaft 64 and also movable in the axial direction of the camshaft 64; a plurality of flat cam forming portions 86 respectively formed into different cam shapes in the intake-side cam 65 and having cam surfaces 85 parallel to the rotating shaft of the camshaft 64; transitional shape portions 88 integrally formed between the flat cam forming portions 86 and having bent cam surfaces 87 continuously connecting the cam surfaces 85; and roller followers 78 having side surfaces corresponding to the cam surfaces 85 and rounded corners corresponding to the bent cam surfaces 87 and driven by the intake-side cam 65. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  As a valve operating device for an engine (internal combustion engine), a variable valve operating device that changes a valve lift amount and an operating angle (valve opening period) is known.

  The variable valve operating device includes a continuous type that continuously changes the valve lift amount and a stage type that can switch the valve lift amount in stages.

  As a continuous variable valve operating device, for example, a cam that is continuously movable in the axial direction of the camshaft while the cam height (proportional to the valve lift amount) and the cam operating angle change continuously in the axial direction of the camshaft. Is known (for example, see Patent Document 1). The continuous variable valve device can control the intake air amount without using a throttle valve by continuously controlling the valve lift amount and the cam operating angle.

  On the other hand, as a stage type variable valve device, for example, a cam height and a cam operating angle are switched in stages in the axial direction of the camshaft, and a rocker arm that is movable in a direction parallel to the rotating shaft of the camshaft is provided. A variable valve apparatus is known (see, for example, Patent Document 2).

JP 2003-3811 A JP 2005-155555 A

  The conventional continuous variable valve device appropriately controls the intake air amount by continuously changing the valve lift amount, thereby improving the engine output, improving the fuel consumption, and purifying the exhaust gas.

  However, since the conventional continuous variable valve apparatus includes a cam having a three-dimensional shape in which the cam height and the cam operating angle continuously change in the axial direction of the camshaft, the cam and the follower (roller follower) are provided. Point contact always occurs, resulting in high contact stress.

  In addition, the conventional continuous variable valve operating device moves the cam having a three-dimensional shape in the axial direction of the camshaft to control the valve lift amount and adjust the intake air amount. High technology is required.

  Furthermore, it is difficult for the conventional continuous variable valve device to provide a difference in the valve lift amount of each intake valve in, for example, a four-valve type engine (two valves each for intake and exhaust). In other words, it is difficult for the continuous variable valve operating device to provide a difference in the valve lift amount of the intake valves of each other and promote swirl (in-cylinder flow) in the cylinder to efficiently burn the fuel.

  On the other hand, when switching the valve lift amount, that is, when changing the contact position between the cam and the follower, it is difficult for the conventional stage type variable valve device to switch at a portion close to the cam nose of each stage. This is a response delay when switching the valve lift amount.

  In addition, since the conventional stage type variable valve device includes a rocker arm that is positioned at one of the steps of the stepped cam surface, similarly to the conventional continuous variable valve device, a valve between a plurality of valves is used. It is difficult to make a difference in the lift amount, and it is difficult to efficiently burn fuel by promoting swirl in the fuel chamber.

  Therefore, the present invention proposes a variable valve operating apparatus that is simple in cam movement control and excellent in the combustion efficiency of the air-fuel mixture and the durability of the cam.

  In order to solve the above-described problems, a variable valve operating apparatus according to the present invention includes a cylinder head having a combustion chamber, a plurality of valves provided in the cylinder head for opening and closing the combustion chamber, and pivotally supported by the cylinder head. A camshaft, a cam portion that rotates integrally with the camshaft and is movable in the axial direction of the camshaft, and a cam that is formed in a different cam shape on the cam portion and is parallel to the rotation axis of the camshaft A plurality of flat cam-shaped portions having a surface, a transition-shaped portion having a curved cam surface integrally formed between the flat cam-shaped portions and continuously connecting the cam surfaces, and a side surface corresponding to the cam surface; A roller follower having a rounded corner corresponding to the curved cam surface and driven by the cam portion; and a rocker arm pivotally supported by the roller follower to open and close the valve. And said that there were pictures.

  The variable valve operating apparatus according to the present invention includes a cylinder head having a combustion chamber, a plurality of valves provided in the cylinder head for opening and closing the combustion chamber, a cam shaft pivotally supported by the cylinder head, A cam portion that is rotated integrally with the cam shaft and is movable in the axial direction of the cam shaft, and a plurality of cam surfaces that are formed in different cam shapes on the cam portion and are parallel to the rotation shaft of the cam shaft. A flat cam shape portion, a transition shape portion formed integrally between the flat cam shape portions and having a curved cam surface continuously connecting the cam surfaces, a side surface corresponding to the cam surface, and a curved cam surface A roller follower having a corresponding rounded corner portion and driven by the cam portion; and a valve lifter that pivotally supports the roller follower to open and close the valve. .

  ADVANTAGE OF THE INVENTION According to this invention, while the movement control of a cam is simple, the variable valve operating apparatus excellent in the combustion efficiency of air-fuel | gaseous mixture and the durability of a cam can be provided.

The left view which showed the motorcycle carrying the variable valve apparatus which concerns on embodiment of this invention. Sectional drawing which showed the variable valve apparatus which concerns on embodiment of this invention. The principal part enlarged view which showed the variable valve apparatus which concerns on embodiment of this invention. The principal part enlarged view which showed the variable valve apparatus which concerns on embodiment of this invention. The principal part enlarged view which showed the variable valve apparatus which concerns on embodiment of this invention. The figure which showed the intake side cam of the variable valve apparatus which concerns on embodiment of this invention from the rotating shaft direction. The figure which showed the protrusion part of the intake side cam of the variable valve apparatus which concerns on embodiment of this invention from the rotating shaft direction. The figure which showed the valve lift curve of the variable valve apparatus which concerns on embodiment of this invention. The figure which showed the valve opening degree map by the variable valve apparatus which concerns on embodiment of this invention. The figure which showed the other example of the variable valve apparatus which concerns on embodiment of this invention. The figure which showed the other example of the variable valve apparatus which concerns on embodiment of this invention.

  Embodiments of a four-cycle engine according to the present invention will be described below with reference to FIGS.

  FIG. 1 is a left side view showing a motorcycle equipped with a variable valve gear according to an embodiment of the present invention.

  As shown in FIG. 1, the motorcycle 1 includes a body frame 2 constituting a framework. The vehicle body frame 2 includes a head pipe 3 installed on the front side, a pair of left and right main frames 4 extending obliquely downward on the rear side from the head pipe 3, and extending downward on the head pipe 3. Down tube 5, a pair of left and right lower tubes 7 having a front end side connected to the lower end of down tube 5 and extending rearward, and an upper end and lower tube 7 connected to the rear end of main frame 4 And a pivot frame 8 having a lower end connected to the rear end.

  The head pipe 3 pivotally supports a steering mechanism 11 disposed on the front side of the vehicle body frame 2.

  The steering mechanism 11 is pivotally supported with respect to the body frame 2 so as to be rotatable in the left-right direction. The steering mechanism 11 is rotatably supported on a steering head 12 pivotally supported on the head pipe 3, a pair of left and right front forks 13 provided on the steering head 12, and a lower portion of the front fork 13. A front wheel 14, a front fender 15 provided on the front fork 13 and covering an upper portion of the front wheel 14, and a handle bar 17 provided above the steering head 12 are provided. The steering mechanism 11 rotates the front wheel 14 left and right by steering applied to the handlebar 17.

  The pair of left and right pivot frames 8 pivotally support a rear wheel suspension device 18 disposed on the rear side of the vehicle body frame 2 so as to be swingable in the vertical direction of the vehicle body frame 2.

  The rear wheel suspension 18 is pivotally attached to a pivot shaft 19 that is installed at the lower end of the pivot frame 8. The rear wheel suspension device 18 includes a swing arm 21 having a front end pivotally attached to a pivot shaft 19, a rear wheel 22 pivotally supported on the rear end of the swing arm 21, and the swing arm 21 on the body frame 2. And a suspension 23 that is elastically supported on the suspension.

  The motorcycle 1 also includes an engine 26 in a space surrounded by the main frame 4, the down tube 5, the lower tube 7, and the pivot frame 24.

  The engine 26 is an internal combustion engine including a cylinder head 28 having a variable valve operating device 27. The intake side of the engine 26 is connected to a throttle body 29 having a throttle valve (not shown), while the exhaust side of the engine 26 is connected to an exhaust pipe 31. The exhaust pipe 31 extends around the right side of the engine 26 and extends behind the vehicle body frame 2. The rear end of the exhaust pipe 31 is connected to the exhaust muffler 32. The power of the engine 26 is transmitted to the rear wheel 22 through a drive sprocket (not shown), a chain 33, and a driven sprocket 34 in order.

  The motorcycle 1 further includes a fuel tank 36 disposed above the engine 26, a rider's seat 37 disposed behind the fuel tank 36, and a rear frame that covers the lower and rear portions of the seat 37. A cover 38 and a rear fender 39 extending from the rear portion of the seating seat 37 toward the rear of the vehicle body frame 2 and covering the upper portion of the rear wheel 22 are provided.

  FIG. 2 is a cross-sectional view showing a variable valve operating apparatus according to an embodiment of the present invention.

As shown in FIG. 2, the cylinder head 28 of the engine 26 includes a combustion chamber 42 formed between the cylinder block 41 and two intake ports 43 (only one in FIG. 2) communicated with the combustion chamber 42. And an exhaust port 44 communicated with the combustion chamber 42. The intake port 43 and the exhaust port 44 are respectively provided with valve seats 46 and 47 at the connection portions with the combustion chamber 42. Further, the cylinder head 28 is an intake valve 48 for opening and closing each intake port 43 (in FIG. 2, Only one is shown), a stem guide 49 that slidably holds the intake valve 48, an exhaust valve 51 that opens and closes the exhaust port 44, a stem guide 52 that slidably holds the exhaust valve 51, and an intake valve 48 and a variable valve operating device 27 that opens and closes each of the exhaust valve 51.

  The intake valve 48 includes an umbrella-shaped valve body 54 and a valve stem 55 extending substantially upward from the valve body 54. The valve body 54 opens and closes the intake port 43 together with the valve seat 46. The valve stem 55 is slidably inserted into the stem guide 49.

  The exhaust valve 51 includes an umbrella-shaped valve body 58 and a valve stem 59 extending substantially upward from the valve body 58. The valve body 58 opens and closes the exhaust port 44 together with the valve seat 47. The valve stem 59 is slidably inserted into the stem guide 52.

  In the side view of the cylinder head 28, the intake valve 48 and the exhaust valve 51 are arranged such that the valve stems 55 and 59 are substantially V-shaped.

  The variable valve operating device 27 is an overhead camshaft type (SOHC: Single OverHead Camshaft, also simply referred to as OHC) valve operating device.

  The variable valve operating device 27 includes a camshaft 64 rotatably supported by the cylinder head 28, an intake side cam 65 (cam portion) provided on the camshaft 64, and a cam profile of the intake side cam 65 ( The intake side rocker arm 61 that lifts the intake valve 48 in accordance with the outer peripheral pattern of the intake side cam 65, the intake side valve spring 66 that biases the intake valve 48 in the closing direction, and the exhaust side cam 67 provided on the camshaft 64. And an exhaust-side rocker arm 62 that lifts the exhaust valve 51 according to the cam profile of the exhaust-side cam 67 (the outer peripheral pattern of the exhaust-side cam 67), and an exhaust-side valve spring 68 that biases the exhaust valve 51 in the closing direction. Prepare.

  The camshaft 64 is positioned substantially at the center between the intake valve 48 and the exhaust valve 51 and is rotatably supported by a cylinder head 28 and a head cover (not shown). The axis of the camshaft 64 is disposed on a substantially extended line at the center of a cylinder (not shown).

  The intake side rocker arm 61 is pivotally supported by a rocker shaft 69 provided in the cylinder head 28. The intake side rocker arm 61 converts the rotational motion of the camshaft 64 into the reciprocating motion of the intake valve 48 according to the cam profile of the intake side cam 65.

  The intake side valve spring 66 is provided between a spring retainer 71 provided at the upper end portion of the valve stem 55 and a spring seat 72 that is loosely fitted to the stem guide 49. The intake side valve spring 66 biases the intake valve 48 in a closing direction via the spring retainer 71. The intake side valve spring 66 presses the valve body 54 against the valve seat 46 by this urging force, and closes the intake port 43.

  The exhaust side cam 67 is formed integrally with the cam shaft 64. The exhaust side cam 67 is provided at an appropriate position where the exhaust valve 51 can be lifted.

  The exhaust-side rocker arm 62 is pivotally supported by a rocker shaft 74 provided on the cylinder head 28. The exhaust side rocker arm 62 converts the rotational movement of the camshaft 64 into the reciprocating movement of the exhaust valve 51 in accordance with the cam profile of the exhaust side cam 67.

  The exhaust side valve spring 68 is provided between a spring retainer 75 provided at the upper end of the valve stem 59 and a spring seat 76 that is loosely fitted to the stem guide 52. The exhaust side valve spring 68 urges the exhaust valve 51 in the closing direction via the spring retainer 75. The exhaust side valve spring 68 presses the valve body 58 against the valve seat 47 by this urging force and closes the exhaust port 44.

  FIG. 3 is an enlarged view of a main part showing the variable valve operating apparatus according to the embodiment of the present invention.

  As shown in FIG. 3, the variable valve apparatus 27 is integrally formed with the camshaft 64 and an intake side cam 65 that is rotated integrally with the camshaft 64 and is movable in the axial direction of the camshaft 64. An exhaust side cam 77, a roller follower 78 driven by the intake side cam 65, an intake side rocker arm 61 pivotally supported by the roller follower 78 to open and close the intake valve 48, and a cam moving mechanism section for moving the intake side cam 65 81 and a cam locking mechanism portion 82 (locking mechanism) that locks the movement position of the intake cam 65 in the axial direction at appropriate intervals.

  The camshaft 64 has a locking ball in / out hole 84 opened in the radial direction.

  The intake side cam 65 is a so-called “three-dimensional cam” in which the cross-sectional shape of the cam continuously changes in the rotation axis direction. The intake-side cam 65 has three or more portions at both ends and an intermediate portion in the direction of the rotation axis, and portions parallel to the rotation axis of the cam shaft 64 (one-dot chain line C in FIG. 3). Specifically, the intake side cam 65 is formed between a plurality of flat cam-shaped portions 86 each having a cam surface 85 formed in different cam shapes and parallel to the rotation axis C of the camshaft 64, and the flat cam-shaped portion 86. A transition shape portion 88 having a curved cam surface 87 that is integrally formed and continuously connects the cam surfaces 85. The intake side cam 65 has a through hole 89 through which the camshaft 64 is inserted.

  The flat cam-shaped portions 86 are arranged so that the portions protruding from the respective base circles are stepped. Further, the flat cam shape portion 86 includes a flat cam shape portion 86a having a cam shape that minimizes the valve lift amount, a flat cam shape portion 86b having a cam shape having an intermediate valve lift amount, and a maximum valve lift amount. A flat cam shape portion 86c having a cam shape is sequentially arranged.

  Further, the flat cam-shaped portion 86 is arranged in the order from the smallest projecting portion to the larger one, specifically, the flat cam-shaped portion 86a, the flat cam-shaped portion 86b, and the flat cam-shaped portion 86c in order of the exhaust cam 77. It is arranged toward.

  The transition shape portion 88 is provided between the flat cam shape portion 86a and the flat cam shape portion 86b and between the flat cam shape portion 86b and the flat cam shape portion 86c, and smoothly connects each of them. The curved cam surface 87 has a curved or arc-shaped cross section and is formed in a curved surface or a spherical shape.

  The through-hole 89 has a plurality of locking grooves 91 that are recessed in the radially outward direction. The respective locking grooves 91 are formed so as to be equally spaced from the moving distance per one time when the intake side cam 65 is moved.

  The roller follower 78 and the intake-side rocker arm 61 correspond to the respective intake valves 48 (hereinafter referred to as “first intake valve 48 a” and “second intake valve 48 b”, respectively) and the first roller follower 78 a and the first rocker arm 61. One intake side rocker arm 61a, a second roller follower 78b, and a second intake side rocker arm 61b are provided.

  The first roller follower 78a and the second roller follower 78b are rollers formed in a rounded round cylindrical shape, and include a side surface 93 parallel to the rotation axis, and a rounded corner portion 94 ( Rounded corners).

  The rotation axis of the roller follower 78 is arranged in parallel to the rotation axis C of the camshaft 64. Therefore, the side surface 93 is disposed in parallel to the cam surface 85 of the flat cam shape portion 86. Thereby, the side surface 93 of the roller follower 78 and the cam surface 85 of the flat cam-shaped portion 86 are brought into contact with each other in a line contact state.

  On the other hand, the rounded corner portion 94 is positioned toward the flat cam shape portion 86 on the larger valve lift side so as to face the curved cam surface 87 of the transition shape portion 88.

  The cam moving mechanism 81 uses a hydraulic cylinder, an electric motor, a stepping motor, and a centrifugal governor as a power source, and applies an axial force that reciprocates the intake cam 65 in the axial direction of the camshaft 64 by a groove cam mechanism or the like. .

  The cam locking mechanism portion 82 loosely fits the locking ball 96 in the locking ball protrusion / retraction hole 84 of the camshaft 64, and urges the locking ball 96 outward in the radial direction of the camshaft 64. And an elastic member 97 positioned in the locking groove 91. When the axial force applied to the intake side cam 65 exceeds a predetermined magnitude, the cam locking mechanism portion 82 immerses the locking ball 96 into the locking ball in / out hole 84 against the urging force of the elastic member 97. Release the lock.

  Further, the cam locking mechanism portion 82 is arranged in parallel in the moving direction of the intake side cam 65 by the urging force of the elastic member 97 once the lock is released and the axial force applied to the intake side cam 65 disappears. A locking ball 96 is locked in the locking groove 91 to stop the movement of the intake side cam 65. At this time, the cam locking mechanism portion 82 locks the intake side cam 65 at a position where the roller follower 78 is driven by the flat cam shape portion 86.

  Further, the cam locking mechanism portion 82 locks the moving positions of the camshaft 64 and the intake side cam 65 at the same intervals as the intervals between the first roller follower 78a and the second roller follower 78b.

  Here, the dimensional relationship between the flat cam-shaped portion 86 and the roller follower 78 will be described.

  First, the cam surfaces 85 of the respective flat cam-shaped portions 86 are arranged at the same distance as the respective roller followers 78. In addition, this separation distance is equal to the movement distance per intake side cam 65 moved by the cam movement mechanism portion 81 and the cam locking mechanism portion 82.

  Specifically, the separation distance L1 between the cam surfaces 85a, 85b, and 85c of the flat cam-shaped portions 86a, 86b, and 86c, the separation distance L2 between the first roller follower 78a and the second roller follower 78b, and the intake side The movement distance L3 per cam 65 has a relationship of separation distance L1 = separation distance L2 = movement distance L3.

  Next, the width of the flat cam-shaped portion 86c having a cam shape that maximizes the valve lift (the length of the camshaft 64 in the rotation axis direction) has a width that allows both intake valves 48 to be opened and closed.

  Specifically, the width of the flat cam-shaped portion 86c is determined by the distance between the cam surfaces 85 of each flat cam-shaped portion 86 and the width of the side surface 93 of the roller follower 78 (the length of the cam shaft 64 in the rotational axis direction). Longer than the sum of More specifically, the width W1 of the flat cam-shaped portion 86c, the separation distance L1 between the respective cam surfaces 85a, 85b, and 85c of the flat cam-shaped portions 86a, 86b, and 86c, and the width W2 of the side surface 93 of the roller follower 78 , Width W1> separation distance L1 + width W2.

  The relationship between the intake side cam 65 and the roller follower 78 will be described in more detail.

  First, the variable valve device 27 (FIG. 3) when the engine 26 is idling will be described.

  As shown in FIG. 3, in the idling state of the engine 26, the variable valve apparatus 27 opens and closes the intake valve 48 by means of a roller follower 78 that is driven by a different flat cam shape portion 86.

  Specifically, the variable valve device 27 opens and closes the first intake valve 48a by the first roller follower 78a driven by the flat cam shape portion 86a, and the second roller follower 78b driven by the flat cam shape portion 86b. To open and close the second intake valve 48b (this state is hereinafter referred to as "first position of intake side cam 65").

  The valve lift amount and cam operating angle of the exhaust valve 51 opened and closed by the flat cam shape portion 86a and the flat cam shape portion 86b are optimized in accordance with the idling state of the engine 26.

  Specifically, the flat cam shape portion 86a is set to have no valve lift or an extremely small valve lift (for example, about 1 mm or less). On the other hand, the flat cam shape portion 86b is set to a valve lift amount that stabilizes idling of the engine 26 in addition to the valve lift amount of the flat cam shape portion 86a. In order to maintain idling of the engine 26, setting a small valve lift amount in the flat cam-shaped portion 86a is sufficient only to open and close one intake valve 48 (here, the second intake valve 48b), while the other. This is to prevent fuel from accumulating on the intake port 43 side of the intake valve 48 (here, the first intake valve 48a). If fuel accumulates on the intake port 43 side of the intake valve 48 (specifically, the valve body 54), the engine output may change steeply when both intake valves 48 are opened as the engine speed increases. This is to avoid this.

  Next, the variable valve operating device 27 near the rotation speed at which the engine 26 generates the maximum torque will be described.

  FIG. 4 is an enlarged view of a main part showing the variable valve operating apparatus according to the embodiment of the present invention.

  As shown in FIG. 4, the variable valve apparatus 27 opens and closes the intake valve 48 by a roller follower 78 driven by a different flat cam shape portion 86 in the vicinity of the rotation speed at which the engine 26 generates the maximum torque. Specifically, the variable valve apparatus 27 opens and closes the first intake valve 48a by the first roller follower 78a driven by the flat cam shape portion 86b, and the second roller follower 78b driven by the flat cam shape portion 86c. To open and close the second intake valve 48b (this state is hereinafter referred to as "second position of the intake side cam 65").

  The valve lift amount and cam operating angle of the exhaust valve 51 opened and closed by the flat cam shape portion 86b and the flat cam shape portion 86c are optimized in accordance with the rotational speed when the maximum torque of the engine 26 is generated.

  Specifically, the flat cam shape portion 86c is set to a valve lift amount that lifts the second intake valve 48b at the maximum opening. On the other hand, the flat cam shape portion 86b is set to the valve lift amount optimized when the maximum torque of the engine 26 is generated together with the valve lift amount (maximum opening degree) of the flat cam shape portion 86c.

  That is, the cam profile of the flat cam-shaped portion 86b is that the idling operation of the engine 26 in combination with the flat cam-shaped portion 86a is stabilized, and the intake amount when the maximum torque of the engine 26 is generated in combination with the flat cam-shaped portion 86c. It is set while maintaining a balance with the optimization of. The intake air amount of the engine 26 is also controlled by a throttle valve.

  Further, the flat cam-shaped portion 86c and the flat cam-shaped portion 86b provide a difference in the valve lift amount between the second intake valve 48b and the first intake valve 48a (solid arrow D in FIG. 4), and the intake port 43 and the fuel. The chamber 42 is connected. Due to the difference in valve lift between the second intake valve 48b and the first intake valve 48a, the variable valve operating device 27 can promote swirl (in-cylinder flow) in the cylinder and efficiently burn the fuel. .

  Next, the variable valve operating device 27 near the rotation speed at which the engine 26 generates the maximum output will be described.

  FIG. 5 is an enlarged view of a main part showing the variable valve operating apparatus according to the embodiment of the present invention.

  As shown in FIG. 5, the variable valve apparatus 27 opens and closes the intake valve 48 by a roller follower 78 driven by the same flat cam-shaped portion 86 in the vicinity of the rotation speed at which the engine 26 generates the maximum output. Specifically, the variable valve operating device 27 opens and closes the intake valve 48 by a roller follower 78 driven by the flat cam-shaped portion 86c (this state is hereinafter referred to as “a third position of the intake side cam 65”). .)

  The valve lift amount of the exhaust valve 51 that is opened and closed by the flat cam shape portion 86c is set to be the maximum.

  Specifically, the flat cam-shaped portion 86c is set to a valve lift amount that lifts the first intake valve 48a and the second intake valve 48b at the maximum opening. As a result, the variable valve device 27 feeds the air-fuel mixture having the maximum flow rate into the cylinder.

  Then, the variable valve apparatus 27 is configured so that when the intake side cam 65 moves in the direction of the rotation axis of the camshaft 64 (that is, the intake side cam 65 changes from the first position to the second position and from the second position to the second position). The roller follower 78 is in contact with the protruding portion of the flat cam-shaped portion 86 when moving to the third position, from the third position to the second position, and from the second position to the first position. Then, the rounded corner portion 94 of the roller follower 78 rides on the transition shape portion 88 of the intake side cam 65, and the valve lift amount of the intake valve 48 is continuously switched.

  FIG. 6 is a view showing the intake side cam of the variable valve operating apparatus according to the embodiment of the present invention from the direction of the rotation axis.

  FIG. 7 is a view showing a protruding portion of the intake side cam of the variable valve operating apparatus according to the embodiment of the present invention from the direction of the rotation axis.

  FIG. 8 is a view showing a valve lift curve of the variable valve operating apparatus according to the embodiment of the present invention.

  As shown in FIGS. 6 and 7, the intake side cam 65 of the variable valve apparatus 27 includes a protruding portion 98 having a cam height (proportional to the valve lift amount) for each flat cam-shaped portion 86. The maximum lift positions of the protruding portions 98 are arranged at different phase angles.

  Further, as shown in FIGS. 7 and 8, the intake side cam 65 of the variable valve apparatus 27 is different in the base point of the protruding portion 98 for each flat cam shape portion 86.

  Specifically, the base point 99a of the flat cam-shaped portion 86a, the base point 99b of the flat cam-shaped portion 86b, and the base point 99c of the flat cam-shaped portion 86c are the rotational directions of the intake side cam 65 (indicated by solid arrows in FIG. 7). ), The base point 99c is positioned at the earliest phase, and the base point 99a is positioned at the latest phase (FIG. 7).

  As a result, during the idling operation of the engine 26, the overlap between the valve lift curve A of the exhaust valve 51 and the valve lift curve B of the intake valve 48 is reduced, and idling is stabilized (FIG. 8).

  On the other hand, when the rotational speed of the engine 26 increases and the maximum torque operation or the maximum output operation is performed, the valve lift curve A of the exhaust valve 51 and the valve lift curve C or the maximum output operation of the intake valve 48 during the maximum torque operation. The overlap with the valve lift curve D of the intake valve 48 at the time increases, and exhaust is promoted by the kinetic energy of the combustion gas (FIG. 8).

  Note that the phase relationship between the base point 99b of the flat cam-shaped portion 86b and the base point 99c of the flat cam-shaped portion 86c can be changed for optimization in each operating state.

  The movement control of the intake side cam 65 by the variable valve operating device 27 will be described.

  FIG. 9 is a view showing a valve opening degree map by the variable valve operating apparatus according to the embodiment of the present invention.

  As shown in FIG. 9, the variable valve operating device 27 controls the cam moving mechanism 81 to move the intake side cam 65 based on the rotational speed of the engine 26 and the opening degree of the throttle valve to move the intake side cam 65. Change the lift amount. The switching control of the intake side cam 65 includes the rotational speed of the engine 26, the opening of the throttle valve, the movement position of the intake side cam 65 (first position, second position, or third position), It is performed based on a so-called three-dimensional map consisting of

  Specifically, the variable valve operating device 27 positions the intake side cam 65 at the first position when the rotational speed of the engine 26 is low and close to idling. Further, the variable valve device 27 positions the intake side cam 65 at the second position when the rotational speed of the engine 26 increases and the rotational speed (the rotational speed R1 in FIG. 9) that generates the maximum torque approaches. . Furthermore, the variable valve device 27 positions the intake side cam 65 at the third position when the rotational speed of the engine 26 increases and the rotational speed that generates the maximum output (rotational speed R2 in FIG. 9) approaches. .

  Further, the variable valve device 27 advances the timing for moving the intake side cam 65 to the larger valve lift amount side with respect to the rotational speed of the engine 26 as the throttle valve opening increases.

  FIG. 10 is a view showing another example of the variable valve operating apparatus according to the embodiment of the present invention.

  As shown in FIG. 10, the variable valve operating apparatus 27A includes a swing arm type intake side rocker arm 61A and an exhaust side rocker arm 62A.

  Thus, the variable valve operating devices 27 and 27A can be applied to both a seesaw type and a swing arm type rocker arm.

  FIG. 11 is a view showing another example of the variable valve operating apparatus according to the embodiment of the present invention.

  As shown in FIG. 11, the cylinder head 28 of the engine 26 includes a variable valve operating device 27 </ b> B that is a double overhead camshaft (DOHC: Double Over Camshaft) valve operating device.

  The variable valve operating device 27B includes an intake side camshaft 101 and an exhaust side camshaft 102 separately. Further, the variable valve operating device 27B is rotated integrally with the intake side camshaft 101 and is rotated integrally with the intake side camshaft 101 and the intake side camshaft 101 which is movable in the axial direction of the intake side camshaft 101. And an exhaust side cam 77 </ b> B that is movable in the axial direction of the exhaust side cam shaft 102.

  The intake side cam 65 </ b> B and the exhaust side cam 77 </ b> B are so-called “three-dimensional cams” in which the cross-sectional shape of the cam continuously changes in the direction of the rotation axis, like the intake side cam 65.

  Thus, the variable valve operating devices 27 and 27A can be applied to a DOHC type valve operating device.

  The variable valve operating devices 27, 27A, 27B include intake-side rocker arms 61, 61A and exhaust-side rocker arms 62, 62A. It can also be applied to a valve device. In this case, the roller follower 78 driven by the cam is provided on the tappet.

  Further, the variable valve operating devices 27, 27A, 27B may appropriately increase or decrease the number of stages of the flat cam-shaped portions 86 of the intake side cams 65, 65B and the exhaust side cam 77B depending on the characteristics of the engine 26.

  The variable valve operating devices 27, 27A, 27B according to the present embodiment configured as described above are configured so that the intake side cams 65, 65B and the exhaust side cam 77B are moved to switch the valve lift amount except when the valve lift amount is switched. 65 and 65B and the exhaust side cam 77B and the roller follower 78 are always in line contact. Thereby, the variable valve operating devices 27, 27A, 27B can alleviate the contact stress generated in the intake side cams 65, 65B, the exhaust side cam 77B and the roller follower 78, as compared with the conventional continuous variable valve operating device.

  Further, the variable valve operating devices 27, 27A, 27B according to the present embodiment are configured such that when the intake side cams 65, 65B and the exhaust side cam 77B are moved to switch the valve lift, the intake side cams are moved by the cam locking mechanism 82. 65, 65B and exhaust side cam 77B are set to the moving distance per one time. Accordingly, the variable valve operating devices 27, 27A, 27B do not need to perform position detection and position control relating to movement at a high level as compared with the conventional continuous variable valve operating device, and the intake side cams 65, 65B and the exhaust side The cam 77B can be moved very easily.

  Furthermore, the variable valve gears 27, 27A, 27B according to the present embodiment can provide a difference in valve lift amount between the first intake valve 48a and the second intake valve 48b. As a result, the variable valve operating devices 27, 27A, 27B can promote the swirl (cylinder flow) in the cylinder and efficiently burn the fuel.

  Furthermore, the variable valve operating devices 27, 27A, 27B according to the present embodiment are formed between the flat cam-shaped portions 86 when the intake side cams 65, 65B and the exhaust side cam 77B are moved to switch the valve lift amount. The valve lift amount can be appropriately switched regardless of the phase angle rotated by the transition shape portion 88.

  Moreover, the variable valve gears 27, 27A, 27B according to the present embodiment can appropriately control the intake amount to the cylinder by combining the valve lift amounts of the first intake valve 48a and the second intake valve 48b.

  Furthermore, the variable valve operating devices 27, 27A, 27B according to the present embodiment do not require complicated opening / closing control with the throttle valve by providing an appropriate phase angle difference in each flat cam-shaped portion 86, so that the intake side The intake valve 48 can be opened at an appropriate operating angle for each switching position of the cams 65 and 65B.

  Furthermore, the variable valve operating apparatuses 27 and 27A according to the present embodiment can position the rounded corner portion 94 of the transition shape portion 88 on the exhaust side cam 77 side by arranging the flat cam shape portions 86a, 86b, and 86c. Therefore, the camshaft 64 can be downsized in the direction of the rotation axis.

  Therefore, according to the variable valve gears 27, 27A, 27B according to the present invention, the movement control of the intake side cams 65, 65B and the exhaust side cam 77B is simple, and the combustion efficiency of the air-fuel mixture and the durability of the cam are improved. An excellent valve train can be constructed.

1 motorcycle 2 body frame 3 head pipe 4 main frame 5 down tube 7 lower tube 8 pivot frame 11 steering mechanism 12 steering head 13 front fork 14 front wheel 15 front fender 17 handle bar 18 rear wheel suspension device 19 pivot shaft 21 swing arm 22 Rear wheel 23 Suspension 24 Pivot frame 26 Engine 27, 27A, 27B Variable valve system 28 Cylinder head 29 Throttle body 31 Exhaust pipe 32 Exhaust muffler 33 Chain 34 Driven sprocket 36 Fuel tank 37 Seating seat 38 Rear frame cover 39 Rear fender 41 Cylinder Block 42 Combustion chamber 42 Fuel chamber 43 Intake port 43 Intake port 44 Exhaust port 48 Intake valve 48a First intake valve 48b First Two intake valves 49 Stem guide 51 Exhaust valve 52 Stem guide 54 Valve body 55 Valve stem 46 Valve seat 58 Valve body 59 Valve stem 47 Valve seat 61, 61A Intake side rocker arm 61a First intake side rocker arm 61b Second intake side rocker Arm 62, 62A Exhaust side rocker arm 64 Cam shaft 65, 65B Intake side cam 66 Intake side valve spring 67 Exhaust side cam 68 Exhaust side valve spring 69 Rocker shaft 71 Spring retainer 72 Spring seat 74 Rocker shaft 75 Spring retainer 76 Spring seat 77 , 77B Exhaust side cam 78 Roller follower 78a First roller follower 78b Second roller follower 81 Cam moving mechanism 82 Cam locking mechanism 84 Locking ball retracting hole 85 Cam surface 86 86a, 86b, 86c Flat cam shape portion 87 Curved cam surface 88 Transition shape portion 89 Through hole 91 Locking groove 93 Side surface 94 Rounded portion 96 Locking ball 97 Elastic member 98 Protruding portion 99a Base point 99b Base point 99c Base point 101 Intake side cam Shaft 102 Exhaust side camshaft

Claims (12)

A cylinder head having a combustion chamber;
A plurality of valves provided in the cylinder head for opening and closing the combustion chamber;
A camshaft supported by the cylinder head;
A cam portion that is integrally rotated with the camshaft and is movable in the axial direction of the camshaft;
A plurality of flat cam-shaped portions each having a cam surface formed in a different cam shape on the cam portion and having a cam surface parallel to a rotation axis of the camshaft;
A transition shape portion having a curved cam surface formed integrally between the flat cam shape portions and continuously connecting the cam surfaces;
A roller follower having a side surface corresponding to the cam surface and a rounded corner portion corresponding to the curved cam surface and driven by the cam portion;
And a rocker arm that pivotally supports the roller follower and opens and closes the valve. A cylinder head having a combustion chamber;
A plurality of valves provided in the cylinder head for opening and closing the combustion chamber;
A camshaft supported by the cylinder head;
A cam portion that is integrally rotated with the camshaft and is movable in the axial direction of the camshaft;
A plurality of flat cam-shaped portions each having a cam surface formed in a different cam shape on the cam portion and having a cam surface parallel to a rotation axis of the camshaft;
A transition shape portion having a curved cam surface formed integrally between the flat cam shape portions and continuously connecting the cam surfaces;
A roller follower having a side surface corresponding to the cam surface and a rounded corner portion corresponding to the curved cam surface and driven by the cam portion;
A variable valve operating apparatus comprising: a valve lifter that pivotally supports the roller follower to open and close the valve. The said flat cam shape part is arrange | positioned sequentially from what has a cam shape from which valve lift amount becomes the minimum to what has a cam shape from which valve lift amount becomes the maximum. Variable valve gear. 4. The variable valve operating apparatus according to claim 1, wherein the maximum lift positions of the respective flat cam-shaped portions are arranged at mutually different phase angles. 5. The valve comprises two intake valves,
5. The variable valve operating apparatus according to claim 1, wherein each of the intake valves is opened and closed by the roller follower driven by the different flat cam-shaped portion. 6. The variable valve operating apparatus according to claim 5, wherein each of the flat cam-shaped portions is spaced apart from the roller follower that opens and closes each of the intake valves. The variable valve operating apparatus according to claim 5 or 6, wherein the two intake valves are opened and closed with the same maximum valve lift amount. 8. The variable valve operating apparatus according to claim 7, wherein the flat cam-shaped portion having a cam shape with a maximum valve lift has a length in a rotation axis direction capable of opening and closing the two intake valves. The variable valve operating apparatus according to any one of claims 1 to 8, further comprising a locking mechanism that appropriately locks the axial movement positions of the cam shaft and the cam portion. The variable valve operating apparatus according to claim 9, wherein the locking mechanism locks the axial movement position of the camshaft and the cam portion at the same interval as the roller follower. The variable valve operating apparatus according to claim 10, wherein the locking mechanism locks the cam portion at a position where the roller follower is driven by the flat cam shape portion. In the variable valve operating device of single overhead camshaft type,
An exhaust cam formed integrally with the camshaft;
The cam portion opens and closes the intake valve,
The flat cam shape portion is sequentially arranged from the cam shape having the smallest valve lift amount to the one having the cam shape having the largest valve lift amount toward the exhaust side cam. The variable valve operating apparatus according to any one of claims 1 to 11.

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