JP2011052546A - Variable valve train - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable valve train switching the operation of an engine valve by sliding a rocker arm in the shaft axis direction of a rocker arm shaft, reducing the rocker arm in weight while including a stopper mechanism making the rocker arm immovable in the shaft axis direction, and making the rocker arm surely and smoothly movable at predetermined timing. <P>SOLUTION: The stopper mechanism 30 includes a stopper ball 46 engaging the rocker arm 13 and the rocker arm shaft 14 with each other, and a plunger 31 biasing the stopper ball 46 to a side for the engagement. The stopper ball 46 is held in a holding hole 39 of the rocker arm shaft 14 and the plunger 31 is held in a groove 41 of a cylinder head 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  2. Description of the Related Art Conventionally, a rocker arm shaft is disposed between one engine valve on the intake or exhaust side of an internal combustion engine and first and second cams for the one engine valve, and a rocker arm shaft that supports the rocker arm in a swingable manner. In accordance with the movement, the rocker arm is slid in the shaft axis direction of the rocker arm shaft so that the rocker arm is selectively engaged with one of the cams to switch the operation of the engine valve. There exists a variable valve mechanism (for example, refer patent document 1). This is provided with a stopper mechanism for maintaining the rocker arm in a non-movable state in order to slide the rocker arm in the shaft axial direction in accordance with the rotation timing of the camshaft. The stopper mechanism includes a ball that is disposed between the rocker arm and the rocker arm shaft and engages them, and a plunger that urges the ball toward the engagement side.

Japanese Utility Model Publication No. 62-21683

  By the way, since the rocker arm swings at a high speed, it is desirable to reduce the mass and reduce the weight, but in the conventional structure, the stopper mechanism is provided in the rocker arm, and the weight of the rocker arm is reduced. Therefore, there is a demand for improvement in this respect.

  Accordingly, the present invention provides a variable valve mechanism that switches the operation of the engine valve by sliding the rocker arm in the shaft axis direction of the rocker arm shaft, and includes a stopper mechanism that makes the rocker arm immovable in the shaft axis direction. It is an object to reduce the weight of the rocker arm and to move the rocker arm reliably and smoothly at a predetermined timing.

As a means for solving the above-mentioned problems, the invention described in claim 1 includes a single engine valve (for example, intake and exhaust valves 6 and 7 of the embodiment) on the intake or exhaust side of an internal combustion engine (for example, the engine 1 of the embodiment), Rocker arms (for example, the respective rocker arms 13, 17 in the embodiment) are arranged between the first and second cams (for example, the left and right first cams 15a, 16a and the left and right second cams 15b, 16b in the embodiment) with respect to the engine valve. The rocker arm is slid in the axial direction of the rocker arm shaft in accordance with the movement of the rocker arm shaft (for example, each rocker arm shaft 14, 18 in the embodiment) that swingably supports the rocker arm. Then, the variable valve mechanism (for example, in the embodiment) that selectively engages the rocker arm with one of the cams to switch the operation of the engine valve. A variable valve mechanism 5), a stopper mechanism (for example, the stopper mechanism 30 of the embodiment) for positioning the rocker arm on the rocker arm shaft is disposed between the rocker arm and the rocker arm shaft, and these are mutually connected. In the variable valve mechanism including a ball to be engaged (for example, the stopper ball 46 of the embodiment) and a plunger (for example, the plunger 31 of the embodiment) for biasing the ball toward the engagement side, the ball Is held by a holding portion (for example, holding hole 39 in the embodiment) provided on the outer peripheral portion of the rocker arm shaft so that the plunger can move to the outer peripheral side of the rocker arm shaft, and the plunger is at one end thereof. An engagement groove (for example, engagement of the embodiment) formed in the rocker arm shaft (for example, the distal end portion 32a of the embodiment). 35) and the other end portion (for example, the base end portion 33a of the embodiment) is held in a groove portion (for example, the groove portion 41 of the embodiment) provided in the cylinder head, and the respective cams are switched. The rocker arm and the rocker arm shaft are integrally swung together via the ball biased by the plunger, and when the respective cams are not switched, the ball is biased by the plunger. In this case, the rocker arm and the rocker arm shaft are unintegrated and only the rocker arm is swung.
According to a second aspect of the present invention, the groove portion includes a lateral groove (for example, the slide groove 42 in the embodiment) along the axial direction of the rocker arm shaft, and a pair of the grooves extending from both ends of the horizontal axis so as to be orthogonal thereto. The engaging groove is inserted through one end of the plunger so as to be able to swing integrally with the rocker arm shaft, and the rocker arm is connected to the plunger. An intermediate portion (for example, the tip portion 33b of the embodiment) is inserted so as not to be relatively movable in the shaft axis direction.
According to a third aspect of the present invention, the plunger has a plunger main body (for example, the plunger main body 32 of the embodiment) constituting one end side thereof, and a cylinder that constitutes the other end side and is inserted through the proximal end side of the plunger main body. A body (for example, the cylinder body 33 of the embodiment) and a biasing member (for example, the biasing member 34 of the embodiment) that is housed in the cylinder body and biases the cylinder body and the plunger main body toward the side away from each other. The base end portion of the cylinder body (for example, the base end portion 33a of the embodiment) presses the inner surface of the groove portion, and the tip end portion of the plunger main body (for example, the tip end portion 32a of the embodiment) engages the ball. The groove portion is formed such that each longitudinal groove is shallower than the transverse groove.
According to a fourth aspect of the present invention, the cylinder body has a distal end portion (for example, the distal end portion 33b of the embodiment) inserted into the rocker arm and a proximal end portion (for example, the proximal end portion 33a of the embodiment) of the cylinder body. It is characterized by being held in the groove of the cylinder head.
In the invention described in claim 5, the cylinder body is formed in a bottomed cylindrical shape, and a bottom portion (for example, a base end portion 33a of the embodiment) which is a base end portion of the cylinder body is held in the groove portion. The thickness of the bottom portion (for example, thickness T in the embodiment) is substantially the same as the depth of the groove portion (for example, depths D1 and D2 in the embodiment).
According to a sixth aspect of the present invention, there is provided a plunger stopper (for example, the plunger stoppers 50 and 60 in the embodiment) for restricting the movement of the plunger during the normal operation in which the respective cams are not switched in the respective longitudinal grooves. ) Is provided.
According to the seventh aspect of the present invention, the engagement groove of the rocker arm shaft is formed to have substantially the same width as the outer diameter of the plunger, and a plurality of the plungers are arranged in the engagement groove, A plurality of corresponding grooves are provided in the cylinder head, and the stopper for the plunger is a vertical groove on one side of the pair of vertical grooves of each groove, and a vertical groove on the other side in the other groove. Thus, each of the plungers is restricted from moving.
The invention described in claim 8 is characterized in that the cylinder head is provided with a holder made of a separate member (for example, the holder 40 of the embodiment), and the groove is formed in the holder.
According to the ninth aspect of the present invention, the holding portion of the rocker arm shaft is a through hole having a mortar-shaped inner peripheral surface extending on the outer peripheral side of the rocker arm shaft, and the ball is fitted into the holding portion, By inserting the rocker arm shaft in a state where the ball is fitted into the rocker arm, the ball is held in the holding portion so as not to fall off, while the holding portion opens into the engaging groove, and each cam When the switching is performed, the rocker arm shaft moves in the shaft axial direction to move the holding portion and the ball to the same position as the plunger in the shaft axial direction, and the ball in the holding portion is moved into the engagement groove by the plunger. By urging from the inside toward the outer periphery of the rocker arm shaft, the rocker arm and the And wherein the engaging the car arm shaft.
According to a tenth aspect of the present invention, in the rocker arm, the plunger is opposed to the holding portion and the ball when the rocker arm shaft moves in the shaft axial direction when the cams are switched. A ball engaging portion (for example, the through holes 47 and 48 in the embodiment) for engaging the stopper ball urged by is provided.

According to the first aspect of the present invention, during normal operation in which the cams are not switched, only the rocker arm is swung to reduce the inertia mass of the variable valve mechanism, while the cams are switched. When the valve is switched, the rocker arm and the rocker arm shaft are integrally swung through the ball, so that the other end of the plunger is moved in the groove of the cylinder head, and the rocker arm is moved in the shaft axial direction. It is possible to restrict movement and cancel it.
Since the plunger is inserted into the rocker arm shaft and held by the cylinder head, the swinging rocker arm does not include the plunger, and the rocker arm can be reduced in weight.
According to the second aspect of the present invention, during the normal operation in which the cams are not switched, the other end of the plunger is held in one of the longitudinal grooves, so that the shaft axial direction of the rocker arm is interposed via the plunger. When the valve is switched when each cam is switched, the rocker arm, the rocker arm shaft, and the plunger are swung together to move the other end of the plunger to the lateral groove side, The movement in the shaft axis direction can be made possible (the movement restriction can be released).
Also, by sliding the plunger together with the rocker arm, the plunger can also be used as a rocker arm slide position restricting part, eliminating the need for a rocker arm slide position restricting part and reducing the number of parts. be able to.
According to the third aspect of the present invention, when the other end of the plunger moves to the lateral groove side during the valve switching when the cams are switched, the plunger is extended and the urging force against the ball is weakened. The engagement force between the rocker arm and the rocker arm shaft is weakened. As a result, the rocker arm can be slid and moved easily and quickly when each cam is switched, and the switching operation of each cam can be performed smoothly.
According to the fourth aspect of the present invention, the cylinder body constituting the plunger is disposed across the rocker arm and the cylinder head, so that the integral plunger is disposed across the rocker arm and the cylinder head. Thus, the switching operation of each cam can be performed smoothly without affecting the urging operation to the ball.
According to the fifth aspect of the present invention, it is possible to reinforce the other end portion of the cylinder body that engages with the groove portion to increase the rigidity, and to reliably control the rocker arm slide movement.
According to the sixth aspect of the present invention, when only the rocker arm swings during the normal operation, the rocker arm shaft and the plunger are prevented from swinging along with this, and other than the plunger during the normal operation, It is possible to prevent the end portion from entering the side of the lateral groove and eliminate the possibility that the stopper mechanism of the rocker arm will come off.
According to the seventh aspect of the present invention, since the engaging groove of the rocker arm shaft is made substantially the same width as the outer diameter of the plunger, even when a plurality of plungers are arranged on this, only the movement of one plunger is restricted. By doing so, it is possible to prevent the rocker arm shaft and each plunger from swinging with the rocker arm during the normal operation. Further, by restricting the movement of the plunger only by the opposite longitudinal grooves of the pair of longitudinal grooves of each groove part, the number of parts of the plunger stopper can be reduced and the size can be reduced.
According to the invention described in claim 8, when the groove is formed, the groove is formed in a relatively small holder as compared with the case where the groove is directly formed in a relatively large cylinder head body. Can be easily processed.
According to the ninth aspect of the present invention, the ball is held between the rocker arm shaft and the rocker arm without forming any special parts or mechanisms, and attached to the ball by the plunger at a predetermined position in the shaft axial direction. By applying the force, the rocker arm and the rocker arm shaft can be engaged with each other to swing together.
According to the invention described in claim 10, when the rocker arm shaft slides, the ball fits into and engages with the ball engaging portion of the rocker arm at a predetermined position in the shaft axial direction. Since the rocker arm shaft and the rocker arm shaft are integrated, the rocker arm and the rocker arm shaft can be integrally swung with a simple configuration without using special parts or mechanisms.

FIG. 2 is a left side view around the cylinder head of the engine in the embodiment of the present invention. It is a top view of the valve mechanism of the said engine, (a) shows at the time of the driving | operation in the low speed rotation area of an engine, (b) shows the time of driving | operation in the high speed rotation area of an engine, respectively. It is a left view including the partial cross section around the rocker arm of the valve mechanism. It is sectional drawing in alignment with the axis line of the rocker arm shaft of the said valve mechanism, (a) shows the time of driving | operation in the engine low speed rotation area, (b) shows the time of driving | operation in the engine high speed rotation area, respectively. It is a top view of the groove part which engages with the plunger of the stopper mechanism which controls the movement of the rocker arm, (a) at the time of operation in the low speed rotation region of the engine, (b) at the time of operation in the high speed rotation region of the engine Respectively. FIG. 5 is a cross-sectional view corresponding to FIG. 4 in a state where a rocker arm shaft is axially moved with respect to the rocker arm. FIG. 7 is a left side view corresponding to FIG. 3 in the state shown in FIG. 6. It is a left view when a rocker arm swings from the state shown in FIG. FIG. 6 is a plan view corresponding to FIG. 5 illustrating the movement of the plunger during cam switching in the order of (a) to (c). It is a top view of the stopper for plungers at the time of normal operation of an engine. It is a top view which shows the movement of the stopper for plungers shown in FIG. 10 in order of (a)-(c). It is a top view which shows the modification of the said stopper for plungers. It is a top view which shows the movement of the stopper for plungers shown in FIG. 12 in order of (a)-(c).

  Embodiments of the present invention will be described below with reference to the drawings. For convenience of explanation, the arrow FR indicates the front, the arrow LH indicates the left side, and the arrow UP indicates the upper side.

  FIG. 1 is a left side view of a cylinder head 2 of a four-stroke DOHC parallel four-cylinder engine 1 used in a prime mover of a vehicle such as a motorcycle. A head cover 3 is mounted on the cylinder head 2, and a valve operating mechanism 5 for driving the intake and exhaust valves 6 and 7 is accommodated in a valve operating chamber 4 formed by these. In the drawing, reference numeral C1 indicates a central axis (cylinder axis) of a cylinder bore in the cylinder body 2a continuous below the cylinder head 2 (base end side).

  Before and after the cylinder head 2, intake and exhaust ports 8 and 9 corresponding to each cylinder are formed. Each of these intake / exhaust ports 8, 9 forms a pair of combustion chamber side openings, and each of the fuel chamber side openings is opened and closed by a pair of intake / exhaust valves 6, 7, respectively. That is, the engine 1 is a four-valve type, and has a pair of left and right intake and exhaust valves 6 and 7 for each cylinder.

  The intake and exhaust valves 6 and 7 are formed by extending rod-shaped stems 6b and 7b to the valve operating chamber 4 side from umbrella-shaped valve bodies 6a and 7a aligned with the combustion chamber side openings, respectively. The stems 6b and 7b of the intake and exhaust valves 6 and 7 are held by the cylinder head 2 so as to be able to reciprocate via valve guides 6c and 7c, respectively. Retainers 6d and 7d are respectively attached to the end portions of the stems 6b and 7b on the valve operating chamber 4 side, and valve springs 6e and 7e are contracted between the retainers 6d and 7d and the cylinder head 2, respectively. .

  The intake and exhaust valves 6 and 7 are urged upward by the spring force of the valve springs 6e and 7e, and the valve bodies 6a and 7a close the combustion chamber side opening. On the other hand, when the intake and exhaust valves 6 and 7 are stroked downward against the urging force of the valve springs 6e and 7e, the valve bodies 6a and 7a of the intake and exhaust valves 6 and 7 are separated from the opening on the combustion chamber side. Release it.

  The stems 6b and 7b of the intake and exhaust valves 6 and 7 are provided so as to be inclined with respect to the cylinder axis C1 so as to form a V shape in a side view. Above each stem 6b, 7b, an intake side camshaft 11 and an exhaust side camshaft 12 are arranged along the left-right direction, respectively. Each of the camshafts 11 and 12 is supported by the cylinder head 2 so as to be rotatable about its axis, and is driven to rotate in conjunction with a crankshaft via, for example, a chain transmission mechanism during operation of the engine 1 (both are Not shown). In addition, the code | symbol C3, C4 in a figure shows the center axis line (cam axis line) of each camshaft 11 and 12. FIG.

  Referring to FIGS. 1 to 3, a pair of left and right intake valves 6 for one cylinder are opened and closed by being pressed by the cam 11 </ b> A of the intake side camshaft 11 via an intake side rocker arm 13 provided for each cylinder. Similarly, a pair of left and right exhaust valves 7 for one cylinder are opened and closed by being pressed by the cam 12A of the exhaust camshaft 12 via an exhaust rocker arm 17 provided for each cylinder.

  The intake side rocker arm 13 is swingable about its axis and slides in the axial direction on an intake side rocker arm shaft 14 disposed in parallel with the intake side camshaft 11 at the rear of the tip portion of the stem 6b of the intake valve 6. It is supported movably. Similarly, the exhaust-side rocker arm 17 is swingable around its axis on an exhaust-side rocker arm shaft 18 disposed in parallel with the exhaust-side camshaft 12 in front of the tip portion of the stem 7b of the exhaust valve 7. Supported to be slidable in the direction. In addition, the code | symbol C5 and C6 in a figure show the center axis line (rocker axis line) of each rocker arm shaft 14 and 18. FIG.

  From the cylindrical boss portion (base portion) 13a through which the intake side rocker arm shaft 14 of the intake side rocker arm 13 is inserted, the arm portion 13b extends toward the distal end portion of the stem 6b of the intake valve 6. A cam roller 13c that is in rolling contact with the cam 11A of the intake camshaft 11 is supported at the tip of the arm portion 13b. A valve pressing portion 13d that abuts against the distal end portion of the stem 6b and presses it downward is provided below the distal end portion of the arm portion 13b. The exhaust-side rocker arm 17 has the same configuration.

  When the engine 1 is in operation, the camshafts 11 and 12 are rotationally driven in conjunction with a crankshaft (not shown), and the rocker arms 13 and 17 are appropriately swung according to the outer peripheral pattern of the cams 11A and 12A. Thus, the rocker arms 13 and 17 press the intake and exhaust valves 6 and 7, respectively, and the intake and exhaust valves 6 and 7 are appropriately reciprocated to open and close the fuel chamber side openings of the intake and exhaust ports 8 and 9.

  Here, the valve mechanism 5 is configured as a variable valve mechanism that can change the valve opening / closing timing and the lift amount of the valves 6 and 7. The valve mechanism 5 opens and closes the valves 6 and 7 using the cams for low-speed rotation in the camshafts 11 and 12 in the low-speed rotation range where the engine speed is less than 9000 rpm (Revolutions Per Minute), for example. In the high-speed rotation range where the rotation speed is 9000 rpm or more, the valves 6 and 7 are opened and closed using the high-speed rotation cams in the camshafts 11 and 12.

Hereinafter, the intake side for one cylinder in the valve operating mechanism 5 will be described as an example, but the intake side of other cylinders and the exhaust side of each cylinder also have the same configuration.
1 and 2, the cam 11A of the camshaft 11 includes left and right first cams 15a and 16a for the low speed rotation region and left and right second cams 15b and 16b for the high speed rotation region. That is, the camshaft 11 has a total of four cams, that is, left and right first cams 15a and 16a and left and right second cams 15b and 16b per cylinder.

  The left and right first cams 15a and 16a have the same shape, and the left and right second cams 15b and 16b have the same shape. The left first cam 15a and the left second cam 15b are adjacent to each other in the left-right direction (cam shaft direction) on the left side of the cylinder, and the right first cam 16a and the right second cam 16b are adjacent to each other on the right side of the cylinder (cam shaft). Direction).

  The rocker arm 13 is swingable about the axis of the rocker arm shaft 14 (the center of the rocker axis C5, hereinafter sometimes referred to as the axis C5) and is axially (the direction along the rocker axis C5, hereinafter referred to as the direction of the axis C5). Is supported in a movable manner. The rocker arm 13 is wide and integrated in the left-right direction so as to extend to the left and right intake valves 6. The cam roller 13c and the valve pressing portion 13d of the rocker arm 13 are provided as a pair separated from each other on the left and right.

  The rocker arm 13 is at the limit position of the leftward movement in the direction of the axis C5 when the operation of the engine 1 is stopped and when the engine 1 is operated in the low speed rotation range (see FIG. 2A). The cam roller 13c is disposed below the left and right first cams 15a and 16a at a position where the cam roller 13c can slide on the outer peripheral surface (cam surface). The left and right valve pressing portions 13d of the rocker arm 13 are provided wider in the left and right direction (axis C5 direction) than the left and right cam rollers 13c, and when the rocker arm 13 is in the leftward movement limit position, The right side of the portion 13d is disposed at a position where the tip of the stem 6b of the left and right intake valve 6 can be pressed. The position of the rocker arm 13 at this time in the direction of the axis C5 is defined as a first operation position.

  On the other hand, the rocker arm 13 is in a limit position to the right in the direction of the axis C5 when the engine 1 is operated in the high speed rotation region (see FIG. 2B). In this state, the left and right cam rollers 13c of the rocker arm 13 Are arranged at positions where they can be slidably contacted with their outer peripheral surfaces (cam surfaces) below the left and right second cams 15b and 16b, respectively. The left and right valve pressing portions 13d of the rocker arm 13 can press the distal end portion of the stem 6b of the left and right intake valves 6 when the rocker arm 13 is in the rightward movement limit position. It is arranged in the position. The position of the rocker arm 13 at this time in the direction of the axis C5 is defined as a second operating position.

  When the rocker arm 13 is in the first operating position, the rocker arm 13 swings according to the outer peripheral pattern of the left and right first cams 15a, 16a to open and close the intake valve 6. On the other hand, when the rocker arm 13 is in the second operating position, the rocker arm 13 swings according to the outer peripheral pattern of the left and right second cams 15b, 16b to open and close the intake valve 6.

  Referring to FIG. 2, the valve mechanism 5 stores a force for moving the rocker arm 13 in the direction of the axis C5 in the first and second rocker arm moving mechanisms 21 and 22 according to the engine speed, and the force is used to By moving the arm 13 to either the first operating position or the second operating position, the left and right first cams 15a and 16a and the left and right second cams 15b and 16b are selectively used for opening and closing the intake valve 6. It can be used for. The first cams 15a and 16a are low-rotation cams (low-speed cams) in which the lift amount of the intake valve 6 is smaller than that of the second cams 15b and 16b. A pause cam (stop cam) may be used.

  In each of the rocker arm moving mechanisms 21 and 22, reference numerals 23 and 24 are located on the left or right side of the boss portion 13a of the rocker arm 13 and force the boss portion 13a from one of the operating positions to the other. Reference numerals 25 and 26 denote spring receiving collars which are located on the left or right side of the springs 23 and 24 and are supported by the rocker arm shaft 14 so as not to move in the axial direction.

  The rocker arm shaft 14 is supported by the cylinder head 2 so as to be movable in the axial direction thereof, and the rocker arm shaft 14 is moved in the axial direction by the operation of an actuator (not shown) or the like. A force for moving the rocker arm 13 is stored in any one of 22.

  The rocker arm shaft 14 and each of the spring receiving collars 25 and 26 are moved to the left in the axial direction when the operation of the engine 1 is stopped and during operation while maintaining the low speed rotation range (low speed operation). (See FIG. 2A). At this time, the rocker arm 13 is in the first operating position, and the springs 23 and 24 are contracted between the boss portion 13 a of the rocker arm 13 and the spring receiving collars 25 and 26.

  On the other hand, the rocker arm shaft 14 and each of the spring receiving collars 25 and 26 are in a limit position to the right in the axial direction when the engine 1 is operated while maintaining a high speed rotation range (during high speed operation). (See FIG. 2 (b)). At this time, the rocker arm 13 is in the second operating position, and the springs 23 and 24 are contracted between the boss portion 13 a of the rocker arm 13 and the spring receiving collars 25 and 26.

  And when moving the rocker arm 13 from one of the operating positions to the other, using the plunger 31 and the groove 41 of the stopper mechanism 30 described later, the movement of the rocker arm 13 in the direction of the axis C5 is restricted. The rocker arm shaft 14 and the spring receiving collars 25 and 26 are moved together in the direction of the axis C5 with respect to the cylinder head 2 to generate a predetermined elastic force difference between the springs 23 and 24 (see FIG. 6). Using this elastic force difference (elastic force accumulated in either one of the springs 23 and 24), the rocker arm 13 can be moved from one of the operating positions to the other.

  Referring to FIGS. 3 and 4, the stopper mechanism 30 includes a plunger 31 inserted along the radial direction at predetermined positions in the axial direction of the boss portion 13 a (base portion) of the rocker arm 13 and the rocker arm shaft 14, and The groove 41 is formed mainly on the cylinder head 2 side and slidably engages with a base end portion of the plunger 31 (a lower end portion in the figure, a base end portion 33a of a cylinder body 33 described later).

  The plunger 31 has a distal end portion (upper end portion in the figure, a distal end portion 32a of a plunger main body 32 described later) inserted into an engagement groove 35 formed in the rocker arm shaft 14 from below, and the base end portion 33a is inserted into the rocker arm. 13 is protruded downward (groove 41 side) from the boss 13a. The base end portion 33a of the plunger 31 is engaged with a groove portion 41 formed on the wall surface of the cylinder head 2 so as to be slidable along the longitudinal direction thereof.

  Here, the groove 41 forming portion of the cylinder head 2 is a holder 40 formed of a separate member with respect to the main body portion of the cylinder head 2. The holder 40 is integrally fixed to the main body portion of the cylinder head 2 by welding or fastening. Hereinafter, the wall surface of the cylinder head 2 (holder 40) is referred to as a groove forming surface W.

  For convenience of illustration, the base end portion 33a of the plunger 31 protrudes below the boss portion 13a and the groove forming surface W is located below the boss portion 13a. However, the base end portion 33a of the plunger 31 is the boss portion. It is good also as a structure which protrudes in back and upper direction of 13a, and the groove formation surface W is located in the extension direction.

  An engagement hole 37 is formed in the boss portion 13a of the rocker arm 13 so that an upper and lower intermediate portion of the plunger 31 (a tip portion 33b of a cylinder body 33 to be described later) can be inserted. The engagement hole 37 has a long oval shape along the circumferential direction of the boss portion 13 a, and an intermediate portion (tip portion 33 b) of the plunger 31 is inserted and held in the engagement hole 37. The plunger 31 inserted through the engagement hole 37 can swing relative to the boss portion 13a by a predetermined amount around the axis C5 (around the shaft axis), and to the boss portion 13a in the axis C5 direction (shaft axis direction). On the other hand, relative movement is impossible.

  Referring also to FIG. 5, the groove portion 41 is formed in a U shape (U shape) that opens toward the boss portion 13 a side of the rocker arm 13 in a plan view (a plan view of the groove forming surface W). And it forms so that a cross-sectional semicircle shape may be extended along this planar view shape. In this groove part 41, the base end part 33a of the plunger 31 which makes a hemisphere engages slidably.

  The groove 41 is a slide groove 42 extending along the shaft axis direction of the rocker arm shaft 14, and is perpendicular to the shaft axis direction from both ends of the slide groove 42 (along the rotation direction of the rocker arm shaft 14. And a pair of restriction grooves 43 extending. The distal end portion of each regulating groove 43 is positioned, for example, directly below the boss portion 13a of the rocker arm 13, and the proximal end portion 33a of the plunger 31 is engaged with one distal end portion of each regulating groove 43. Movement of the rocker arm 13 in the direction of the axis C5 during normal operation where the cam is not switched is restricted.

  On the other hand, at the time of valve switching when each cam is switched, the plunger 31 swings around the axis C5 together with the rocker arm shaft 14 due to the engagement of the rocker arm 13 and the rocker arm shaft 14 via a stopper ball 46 described later. And the base end portion 33a is moved to the base end side (sliding groove 42 side) of each regulating groove 43. At this time, if the force sufficient to move the rocker arm 13 from one of the operating positions to the other is stored in any of the rocker arm moving mechanisms 21 and 22, the base end portion 33a of the plunger 31 slides. When the groove 42 is reached, the rocker arm 13 moves in the direction of the axis C5 together with the plunger 31. Thereafter, the base end portion 33a of the plunger 31 is engaged with the other tip end portion of each restriction groove 43, so that the movement in the direction of the axis C5 is restricted in a state where the rocker arm 13 is moved to the other of the respective operation positions. Is done.

  The engagement groove 35 of the rocker arm shaft 14 has a slit shape along the shaft axial direction, and extends in the shaft axial direction with substantially the same width as the outer diameter of the distal end side (plunger main body 32) of the plunger 31. The engaging groove 35 allows the relative movement of the plunger 31 in the shaft axis direction while being inserted through the distal end side of the plunger 31, but disables the relative swinging of the plunger 31 around the shaft axis.

The plunger 31 is restrained from moving to the proximal end side by being actuated by a plunger stopper 50 described later in a state where the plunger 31 is engaged with any of the distal end portions of the regulating grooves 43.
As a result, during the normal operation of the engine 1, the swing (rotation) of the plunger 31 and the rocker arm shaft 14 that holds the plunger 31 accompanying the swing of the rocker arm 13 is restricted. This prevents the restriction of the movement of the rocker arm 13 in the axial direction by moving to the base end side of the restriction groove 43. At this time, the plunger insertion portion (engagement hole 37) of the boss portion 13a of the rocker arm 13 is formed long in the circumferential direction of the boss portion 13a, so that the rocker arm 13 is inserted even when the plunger 31 is inserted through the boss portion 13a. Only can swing.

  The engagement groove 35 of the rocker arm shaft 14 is formed at a predetermined depth from the lower end (the groove part 41 side end) of the rocker arm shaft 14 upward. A holding hole 39 that communicates the inside of the engaging groove 35 and the outer peripheral side of the rocker arm shaft 14 is formed in the longitudinal intermediate portion of the bottom (ceiling) of the engaging groove 35. The holding hole 39 has a mortar-shaped inner surface that expands toward the outer peripheral side of the rocker arm shaft 14, and the stopper ball 46 is fitted into the holding hole 39 from the outer peripheral side of the rocker arm shaft 14. The stopper ball 46 is made of a steel ball, and is prevented from falling into the engagement groove 35 by being in contact with and supported by the inner peripheral surface of the holding hole 39 and is movable to the outer peripheral side of the rocker arm shaft 14. Kept in a state.

  In this state, when the rocker arm shaft 14 is inserted into the boss portion 13 a of the rocker arm 13, the stopper ball 46 is held in the holding hole 39 so as not to fall off. At this time, the rocker arm shaft 14 is moved in the axial direction to move the stopper ball 46 and the holding hole 39 to the same position as the plunger 31 in the shaft axial direction, so that the stopper ball 46 in the holding hole 39 is moved by the plunger 31. It is urged toward the upper side (the outer peripheral side of the rocker arm shaft 14).

Here, the plunger 31 is divided into a plunger main body 32 constituting the distal end side and a cylinder body 33 constituting the proximal end side.
The plunger main body 32 has a cylindrical shape having a hemispherical distal end surface, and the proximal end side of the plunger main body 32 is inserted into the distal end side of the bottomed cylindrical cylinder body 33 so as to allow a stroke. A biasing member 34 such as a coil spring is contracted between the bottom surface of the cylinder body 33 and the base end surface of the plunger main body 32.

  The plunger body 32 is provided so that the distal end surface thereof is brought into contact with the bottom surface (ceiling surface) of the engagement groove 35 and the proximal end side is projected downward from the end of the rocker arm 13 on the groove portion 41 side of the boss portion 13a. It is done. The distal end side of the plunger main body 32 is inserted and held in the engagement groove 35 of the rocker arm shaft 14.

  The cylinder body 33 is inserted into the groove 41 side end of the boss portion 13a of the rocker arm 13 so that the distal end portion 33b does not reach the outer peripheral surface of the rocker arm shaft 14, and the base end portion 33a is a groove portion of the cylinder head 2. 41 is provided so as to enter into 41. The base end portion 33a of the cylinder body 33 forms a hemispherical base end surface.

  For example, when an integral plunger is arranged over the rocker arm shaft 14, the rocker arm 13, and the cylinder head 2, the plunger slide is affected and the biasing operation to the stopper ball 46 can be performed smoothly. Although it is conceivable that the plunger 31 divided as described above is used, the sliding of the plunger main body 32 is hardly affected, and the urging operation to the stopper ball 46 can be performed smoothly.

  7 and 8, the thickness T of the base end portion 33a (bottom portion) of the plunger 31 (cylinder body 33) is equal to or greater than the depth D2 of at least the tip end portion of the restriction groove 43 of the groove portion 41. . Further, the thickness T of the base end portion 33a is substantially equal to the depth D1 of the slide groove 42.

  Referring to FIGS. 3 and 4, the plunger 31 is configured so that the front end surface (upper end surface) of the plunger main body 32 becomes the bottom surface (ceiling surface) of the engaging groove 35 during the normal operation by the urging force of the urging member 34. While pressing, the base end surface (lower end surface) of the cylinder body 33 is pressed against the bottom surface (inner surface) of the groove portion 41. At this time, the stopper ball 46 is not urged by the plunger 31 and the stopper ball 46 does not engage the rocker arm 13 and the rocker arm shaft 14. It will be in a swingable state.

  On the other hand, referring to FIGS. 6 and 7, at the time of valve switching in which each cam is switched, the holding hole 39 and the stopper ball 46 move to the same position in the direction of the plunger 31 and the axis C5 due to the axial movement of the rocker arm shaft 14. . Accordingly, the base end surface of the cylinder body 33 presses the bottom surface of the groove portion 41, and the distal end surface of the plunger main body 32 biases the stopper ball 46 toward the side where the rocker arm 13 and the rocker arm shaft 14 are engaged with each other.

  4 and 5, the plunger 31 and the groove 41 are provided in a pair of left and right with respect to one rocker arm 13. The plungers 31 are arranged so as to be distributed at substantially equal intervals on both sides of the stopper ball 46 and the holding hole 39 during the normal operation. The base end portions 33a of the plungers 31 engage with the same side of the pair of regulating grooves 43 of the groove portions 41, respectively.

  In each groove portion 41, the left one of the pair of restriction grooves 43 in the figure engages with the plunger 31 when the rocker arm 13 is in the first operating position (FIG. 4A). 5 (a)), the right side of the pair of regulating grooves 43 in the figure is engaged with the plunger 31 when the rocker arm 13 is in the second operating position (FIG. 4 (b), (Refer FIG.5 (b)).

  Hereinafter, the left plunger 31 and the groove 41 in the figure may be referred to as the left plunger 31a and the left groove 41a, respectively, and the right plunger 31 and the groove 41 may be referred to as the right plunger 31b and the right groove 41b, respectively. In addition, the left first restriction groove 44a and the left second restriction groove 44b are respectively provided in the restriction groove 43 of the left groove portion 41a, and the right first restriction groove 45a and the right second groove are provided in the right groove portion 41b. It may be referred to as a second restricting groove 45b. The left and right first restriction grooves 44a and 45a correspond to low speed cams with a relatively small lift amount, and the left and right second restriction grooves 44b and 45b correspond to high speed cams with a relatively large lift amount. The left and right second restriction grooves 44b and 45b are longer than the one restriction groove 44a and 45a.

Through holes 47 and 48 having a diameter smaller than that of the stopper ball 46 are formed on the left and right sides of the end portion of the boss portion 13a opposite to the groove portion 41, respectively. The through holes 47 and 48 are provided so as to be at the same position as the plunger 31 in the direction of the axis C5, but are provided at positions shifted by a predetermined angle around the axis C5 with respect to a position on the extension of the plunger 31. It is done.
In the normal operation, only the bottom portion (ceiling portion) of the engagement groove 35 is sandwiched between each plunger 31 and the through holes 47, 48. When the shaft 14 slides (see FIG. 6) and the rocker arm 13 is pressed by the cam and swings (see FIG. 7) (see FIG. 7), between each plunger 31 and one of the through holes 47 and 48 (see FIG. 7). The stopper ball 46 and the holding hole 39 are moved and sandwiched between the extension of each plunger 31).

  Then, the stopper ball 46 that is in contact with and supported by the inner peripheral surface of the holding hole 39 is pushed upward (on the outer peripheral side of the rocker arm shaft 14) by the distal end portion 32 a of the plunger 31 that has entered the holding hole 39. And fits to any of the through holes 47 and 48. As a result, the rocker arm shaft 14 and the rocker arm 13 (boss portion 13a) are engaged with each other via the stopper ball 46 and can swing together. In this state, the cam is released and the rocker arm 13 is rocked. When returning to the state before moving (swings in the opposite direction), the rocker arm shaft 14 also swings (rotates) integrally (see FIG. 8).

  At this time, the plungers 31 inserted in the engagement grooves 35 so as not to swing relative to each other also swing in the same manner, and the base end portion 33a resists the urging force of the plunger stopper 50 described later to restrict the grooves. It moves to the base end side of 43 (refer Fig.9 (a)). Thereby, the base end portion 33a of each plunger 31 reaches the slide groove 42 from the corresponding restriction groove 43, and each plunger 31 and the rocker arm 13 can move in the shaft axis direction.

  The through holes 47 and 48 may be recesses formed on the inner periphery of the boss 13a as long as the stopper ball 46 can be engaged. Further, as described above, when the stopper ball 46 and the holding hole 39 are moved between any one of the plungers 31 and the through holes 47 and 48 by the axial movement of the rocker arm shaft 14, the other of the plungers 31 is moved. By contacting the end of the engagement groove 35 in the axial direction, further movement of the rocker arm shaft 14 in the axial direction is restricted (see FIG. 6).

  The switching operation of each cam is performed, for example, when the rocker arm 13 swings. That is, when the rocker arm shaft 14 is moved in the axial direction by the operation of the actuator with respect to the rocker arm 13 whose movement in the shaft axial direction is restricted by the stopper mechanism 30, the rocker arm moving mechanisms 21 and 22 A force sufficient to move the rocker arm 13 from one of the operating positions to the other is stored in any one of the positions (see FIG. 6).

  At this time, the stopper ball 46 and the holding hole 39 move to the same positions as the plungers 31 and the through holes 47 and 48 in the direction of the axis C5, and when the rocker arm 13 swings in this state, the stopper ball 46 and the holding hole 39 are moved. It moves on the extension of the plunger 31. At this time, the stopper ball 46 in the holding hole 39 is pushed upward by the plunger 31 so that the rocker arm shaft 14 and the rocker arm 13 (boss portion 13a) are engaged with each other and integrated (FIG. 6). 7).

  In this state, when the rocker arm 13 returns to the state before swinging (swings in the reverse direction), the rocker arm shaft 14 and each plunger 31 also swing (rotate) integrally with this, and each plunger 31 The base end portion 33a moves from the front end side of the corresponding restriction groove 43 to the base end side to reach the slide groove 42 (see FIGS. 8 and 9A). As a result, the movement restriction of the rocker arm 13 in the shaft axis direction is released, and the rocker arm 13 is quickly moved from one of the operating positions to the other by the force accumulated in either of the rocker arm moving mechanisms 21 and 22. To do. At this time, the base end portion 33a of each plunger 31 moves from the base end side of one restriction groove 43 to the base end side of the other restriction groove 43 (see FIG. 9B).

  When the rocker arm 13 moves from one of the operating positions to the other, the plunger 31 and the through holes 47 and 48 also move in the shaft axial direction together with the rocker arm 13, and one of the plunger 31 and one of the through holes 47 and 48 moves. The stopper ball 46 and the holding hole 39 are retracted from the gap. As a result, the engagement between the rocker arm shaft 14 and the rocker arm 13 via the stopper ball 46 is released.

  Thereafter, the plunger 31 receives an urging force from a plunger stopper 50, which will be described later, and the plunger 31 abuts against the longitudinal end of the engagement hole 37 of the boss portion 13a and is pushed back, so that the plunger 31 and the rocker arm shaft 14 are pushed back. Return to the state before the swing. Thereby, the plunger 31 moves to the front end side of the corresponding restriction groove 43 (see FIGS. 3 and 9C), and restricts the movement of the rocker arm 13 in the axial direction at the other of the operation positions.

  Here, referring to FIGS. 7 and 8, each groove portion 41 is formed such that each regulating groove 43 is shallower than the sliding groove 42. More specifically, in each groove portion 41, the depth D 2 on the distal end side of each restriction groove 43 is formed to be shallower than the base end side of each restriction groove 43 and the depth D 1 of the slide groove 42. Has been.

  Thereby, the distance (full length) L between the both end portions of the plunger 31 is short when the base end side is engaged with the tip end side of each regulating groove 43, and the base end side is the base end of each regulating groove 43. It is longer when engaged with the side and slide grooves 42. The amount of compression of the biasing member 34 also changes with the change in the overall length of the plunger 31, so that when the base end portion 33 a of the plunger 31 is on the distal end side of the regulating groove 43, the plunger 31 is attached to the stopper ball 46. When the force is strengthened and the proximal end side of the plunger 31 is in the proximal end side of the restriction groove 43 and the slide groove 42, the biasing force of the plunger 31 on the stopper ball 46 is weakened.

  The time when each cam is not switched is a state in which the engine 1 is operating at a rotational speed before and after the predetermined rotational speed without straddling a predetermined rotational speed (normal operation state). When it is made, it is an operating state in which the engine speed increases or decreases across the predetermined speed. Then, by swinging only the rocker arm 13 during the normal operation, the inertial mass of the valve operating mechanism 5 is reduced and its operability is improved.

  Referring to FIGS. 10 and 11, the cylinder head 2 side (holder 40) is provided with a plunger stopper 50 for holding each plunger 31 on the tip side of the corresponding regulating groove 43 during the normal operation. Hereinafter, description will be made using the directions (up, down, left, right) shown in the figure.

  The plunger stopper 50 mainly includes a pair of left and right arm bodies 51 and 52 extending along the groove forming surface W of the holder 40. The arm bodies 51 and 52 can swing around the support shaft 53 by inserting a support shaft 53 erected from the groove forming surface W into the base end portion. Each arm body 51, 52 extends from the base end portion to the left and right outer sides, and then bends so that its distal end side is changed upward.

  Lower sides 51a and 52a having arcuate shapes in plan view are formed on the distal ends of the arm bodies 51 and 52, respectively. The support shaft 53 rises from the groove forming surface W between the groove portions 41, and the arm bodies 51, 52 extending from the support shaft 53 to the left and right outer sides are one of the pair of restriction grooves 43 of the groove portions 41. Is arranged so that the lower sides 51a and 52a and the periphery thereof are overlapped.

  Specifically, the lower side 51a of the left arm body 51 is disposed so as to overlap the base end side of the left first restriction groove 44a of the left groove portion 41a in plan view, and the lower side 52a of the right arm body 52 is formed of the right groove portion. It arrange | positions so that it may overlap with the base end side of the groove | channel 45b for 2nd right regulation of 41b in planar view. In other words, the lower sides 51a and 52a of the arm bodies 51 and 52 are arranged so as to overlap with the base end sides of the opposing ones of the pair of regulating grooves 43 of the groove portions 41a and 41b in plan view.

  The arm bodies 51 and 52 are biased by a biasing member 54 such as a coil spring so that the periphery of the lower sides 51a and 52a is superimposed on the base end side of the corresponding restriction groove 43. In this state, one of the lower sides 51 a and 52 a of the arm bodies 51 and 52 urges the plunger 31 that engages with any of the opposite restricting grooves 43 toward the distal end side of the restricting groove 43. . Thereby, the separation of the plunger 31 from the front end side of the regulating groove 43 is suppressed, and thus the rotation of each plunger 31 and the rocker arm shaft 14 accompanying the rocking of the rocker arm 13 is suppressed.

  When each plunger 31 moves from one restriction groove 43 of each groove portion 41 to the other restriction groove 43, first, the plunger 31 pressed by one of the arm bodies 51 and 52 is In order to move to the base end side of the engaging regulating groove 43, the lower side is pushed upward while sliding on one of the lower sides 51a, 52a of each arm body 51, 52, and one of the arm bodies 51, 52 is It is swung upward against the urging force (see FIG. 11A).

  Next, when each plunger 31 moves from one restricting groove 43 side to the other restricting groove 43 side through the sliding groove 42 of each groove portion 41, one of the arm bodies 51, 52 retracts the corresponding plunger 31. , The plunger 31 corresponding to the other of the lower sides 51a and 52a of the arm bodies 51 and 52 slides from the side and pushes the lower side upward, so that the arm bodies 51 and 52 The other is swung upward against the biasing force (see FIG. 11B).

  The plunger 31 that oscillates the other of the arm bodies 51 and 52 returns to the state before the rocker arm 13 and is pressed upward from the other of the arm bodies 51 and 52. It moves to the tip side of the groove 43. Thereby, each arm body 51 and 52 will return to the state before rocking | fluctuation, and it will be in the state by which one of each plunger 31 was pressed upward by the corresponding arm body 51 and 52. FIG.

  In this way, by restricting the movement of only one of the plungers 31 engaged with the respective groove portions 41, the swing (rotation) of each plunger 31 and the rocker arm shaft 14 accompanying the swing of the rocker arm 13 is restricted. can do.

12 and 13 show a plunger stopper 60 which is a modification of the plunger stopper 50.
The plunger stopper 60 mainly includes an integral stopper plate 61 having a plan view. The stopper plate 61 is provided in correspondence with one groove 41 (referred to as the left groove 41a in the figure). The stopper plate 61 is arranged along the groove forming surface W of the holder 40, and both arm parts 62, 63 are arranged so as to overlap the base end side of each regulating groove 43 of the groove part 41 in plan view. .

  An oblong through hole 64 that is long in the vertical direction is formed above the left and right intermediate portions of the stopper plate 61, and a support shaft 65 that rises from the holder 40 is inserted into the through hole 64. Thereby, the stopper plate 61 can swing around the support shaft 65 along the groove forming surface W of the holder 40 and can move up and down by a predetermined amount along the through hole 64.

  Both arm portions 62 and 63 of the stopper plate 61 are formed with inner sides 62a and 63a that are arc-shaped in plan view on the lower inner side. The stopper plate 61 is biased so as to be in a state (neutral state) in which the inner sides of both arm portions 62 and 63 are overlapped with the base end side of each regulating groove 43. In this state, One of 62a and 63a biases the plunger 31 (referred to as the left plunger 31a in the figure) that engages with any one of the restriction grooves 43 toward the distal end side of the restriction groove 43. Thereby, detachment | leave from the said groove | channel 43 for a restriction | limiting of the plunger 31 is suppressed, and the rotation of the plunger 31 and the rocker arm shaft 14 accompanying rocking | fluctuation of the rocker arm 13 is suppressed.

  When the plunger 31 moves from one restricting groove 43 to the other restricting groove 43, first, the plunger 31 is moved to the base end side of the one restricting groove 43 so that the stopper plate 61 While sliding in contact with one of the inner sides 62a and 63a, one of the inner sides 62a and 63a is pushed upward to swing the stopper plate 61 against the biasing force (see FIG. 13A). At this time, the plunger 31 enters between the arms 62 and 63 of the stopper plate 61.

  Next, when the plunger 31 moves from the one restricting groove 43 side to the other restricting groove 43 side through the slide groove 42, the stopper plate 61 swings to the opposite side when pushed up by the plunger 31, From the state shown in FIG. 13 (a), the swing state is reversed left and right (the state shown in FIG. 13 (b)).

  Thereafter, the plunger 31 returns to the state before the rocker arm 13 and moves upward to the front end side of the corresponding restriction groove 43 by being pressed upward from the stopper plate 61. Accordingly, the stopper plate 61 returns to the neutral state, and the plunger 31 is pressed upward by the stopper plate 61 (see FIG. 13C).

  In this way, by restricting the movement of only the plunger 31 that engages with the one groove 41, the plunger stopper 60 and the rocker arm shaft accompanying the rocking of the rocker arm 13 can be achieved while the plunger stopper 60 is downsized. The swinging (turning) of 14 can be restricted.

  As described above, the variable valve mechanism 5 in the above embodiment includes the intake valve 6 (or the exhaust valve 7) of the engine 1, the left and right first cams 15a and 16a and the left and right second cams 15b for the intake valve 6. The intake-side rocker arm 13 (or the exhaust-side rocker arm 17) is disposed between the intake-side rocker arm 13 and the exhaust-side rocker arm shaft 14 (or the exhaust-side rocker arm shaft 18). Accordingly, the rocker arm 13 is slid in the shaft axis direction of the rocker arm shaft 17 so that the rocker arm 13 is selected as one of the first cams 15a and 16a and the second cams 15b and 16b. The operation of the intake valve 6 is switched by engaging the rocker arm 13 with the rocker arm 13. A stopper mechanism 30 for positioning on the camshaft shaft 14 is provided between the rocker arm 13 and the rocker arm shaft 14 and engages the stopper ball 46 and the stopper ball 46 on the side on which the stopper ball 46 is engaged. A holding hole 39 provided in the outer peripheral portion of the rocker arm shaft 14 so that the stopper ball 46 can move to the outer peripheral side of the rocker arm shaft 14. The plunger 31 is inserted into the engagement groove 35 formed in the rocker arm shaft 14 at one end portion (tip portion 32a) and the other end portion (base end portion 33a) into the cylinder head 2. When the respective cams are switched by being held in the groove 41 provided, the plunger 31 If the rocker arm 13 and the rocker arm shaft 14 are integrated and rocked together via the biased stopper ball 46, while the cams are not switched, the stopper ball 46 moves to the plunger 31. Without being biased, the rocker arm 13 and the rocker arm shaft 14 are unintegrated and only the rocker arm 13 is swung.

According to this configuration, during the normal operation in which the cams are not switched, only the rocker arm 13 is swung to reduce the inertia mass of the variable valve mechanism 5, while the valve switching is performed to switch the cams. Sometimes, the rocker arm 13 and the rocker arm shaft 14 are integrally swung through the stopper ball 46 to move the other end portion of the plunger 31 in the groove portion 41 of the cylinder head 2, and the rocker arm 13. It is possible to restrict movement in the shaft axis direction and to cancel it.
Since the plunger 31 is inserted into the rocker arm shaft 14 and held by the cylinder head 2, the rocker arm 13 that swings does not include the plunger 31, and the weight of the rocker arm 13 can be reduced. .

  The variable valve mechanism 5 includes a sliding groove 42 along the axial direction of the rocker arm shaft 14 and a pair of regulating grooves 43 that extend from both ends of the horizontal axis so as to be orthogonal thereto. It consists of

According to this configuration, during the normal operation in which each cam is not switched, the other end portion of the plunger 31 is held in one of the restriction grooves 43, so that the shaft axis direction of the rocker arm 13 is interposed via the plunger 31. When the valve is switched while each cam is switched, the rocker arm 13, the rocker arm shaft 14 and the plunger 31 are integrally swung so that the other end of the plunger 31 is moved to the slide groove 42 side. The rocker arm 13 can be moved in the shaft axis direction (the movement restriction can be released).
Further, by sliding the plunger 31 together with the rocker arm 13, the plunger 31 can be used as a part for restricting the slide position of the rocker arm 13. The number of points can be reduced.

  The variable valve mechanism 5 includes a plunger main body 32 that constitutes one end side of the plunger 31, a cylinder body 33 that constitutes the other end side and passes through the proximal end side of the plunger main body 32, The urging member 34 is accommodated in the cylinder body 33 and urges the cylinder body 33 and the plunger main body 32 toward the side away from each other. The base end portion 33a of the cylinder body 33 is the inner surface (bottom surface) of the groove portion 41. , And the tip end portion 32a of the plunger main body 32 urges the stopper ball 46 to engage with the stopper ball 46, and the groove portion 41 has a restriction groove with respect to the slide groove 42. 43 is formed shallow.

  According to this configuration, when the other end of the plunger 31 moves toward the slide groove 42 when the valves are switched, the plunger 31 extends and the urging force against the stopper ball 46 is weakened. The engagement force between the rocker arm 13 and the rocker arm shaft 14 via the ball 46 is weakened. As a result, the rocker arm 13 can be slid easily and quickly at the time of switching of each cam, and the switching operation of each cam can be performed smoothly.

  In the variable valve mechanism 5, the cylinder body 33 has the distal end portion 33 b inserted into the plunger insertion portion (engagement hole 37) of the rocker arm 13 and the base end portion 33 a is held in the groove portion 41. It is something to be made.

  According to this configuration, when the cylinder body 33 constituting the plunger 31 is disposed across the rocker arm 13 and the cylinder head 2, the integral plunger 31 is disposed across the rocker arm 13 and the cylinder head 2. As compared with the above, the switching operation of each cam can be performed smoothly without affecting the urging operation to the stopper ball 46.

  In the variable valve mechanism 5, the cylinder body 33 constituting the plunger 31 is formed in a bottomed cylindrical shape, and the bottom portion (base end portion 33 a) of the cylinder body 33 is held by the groove portion 41. The thickness T of the bottom is substantially the same as the depths D1 and D2 of the groove 41.

  According to this configuration, it is possible to reinforce the other end portion of the cylinder body 33 on the side engaged with the groove portion 41 to increase the rigidity, and to reliably control the sliding movement of the rocker arm 13.

  Further, the variable valve mechanism 5 includes a plunger stopper 50 (or a regulator 50) that restricts the plunger 31 from moving (swinging) in the regulation grooves 43 during normal operation when the cams are not switched. 60).

  According to this configuration, when only the rocker arm 13 swings during the normal operation, the rocker arm shaft 14 and the plunger 31 are prevented from swinging along with this, and the other end of the plunger 31 is rotated during the normal operation. Therefore, it is possible to prevent the stopper mechanism 30 of the rocker arm 13 from coming off by preventing the portion from entering the slide groove 42 side.

  In the variable valve mechanism 5, the engagement groove 35 of the rocker arm shaft 14 is formed to have substantially the same width as the outer diameter of the plunger 31, and a plurality of the plungers 31 are arranged in the engagement groove 35. In addition, a plurality of groove portions 41 corresponding to the respective plungers 31 are provided in the cylinder head 2, and the plunger stopper 50 is located on one side of one of the pair of restriction grooves 43 of each groove portion 41. The restriction groove 43 and the other groove portion 41 restrict the movement (swing) of the plunger 31 in the restriction groove 43 on the other side.

  According to this configuration, since the engagement groove 35 of the rocker arm shaft 14 has substantially the same width as the outer diameter of the plunger 31, even when a plurality of plungers 31 are arranged on this, only one plunger 31 is swung. By restricting, it is possible to prevent the rocker arm shaft 14 and the plungers 31 from swinging around the rocker arm 13 during the normal operation. Further, by restricting the movement of the plunger 31 only by the opposing restriction groove 43 of the pair of restriction grooves 43 of each groove portion 41, the number of parts of the plunger stopper 50 can be reduced and the size can be reduced. be able to.

  The variable valve mechanism 5 is provided with a holder 40 made of a separate member in the cylinder head 2, and the groove portion 41 is formed in the holder 40.

  According to this configuration, when the groove portion 41 is formed, the groove portion 41 is formed in the relatively small holder 40 as compared with the case where the groove portion 41 is directly formed in the relatively large cylinder head 2 body. Can be easily processed.

  In the variable valve mechanism 5, the holding hole 39 of the rocker arm shaft 14 is a through hole having a mortar-shaped inner peripheral surface that extends to the outer peripheral side of the rocker arm shaft 14. The stopper ball 46 is fitted, and the stopper ball 46 is inserted into the boss portion 13a of the rocker arm 13 so that the stopper ball 46 cannot be dropped into the holding hole 39. On the other hand, the holding hole 39 opens into the engagement groove 35, and when the cams are switched, the rocker arm shaft 14 moves in the axial direction of the shaft and the holding hole 39 and the stopper ball 46 are moved. Is moved to the same position as the plunger 31 in the shaft axial direction, and the stopper ball in the holding hole 39 is moved. The rocker arm 13 and the rocker arm shaft 14 are engaged with each other via the stopper ball 46 by urging 6 from the inside of the engagement groove 35 toward the outer peripheral side of the rocker arm shaft 14 by the plunger 31. is there.

  According to this configuration, the stopper ball 46 is held between the rocker arm shaft 14 and the rocker arm 13 without configuring special parts or mechanisms, and the stopper ball 46 is held by the plunger 31 at a predetermined position in the shaft axial direction. By applying an urging force to the rocker, the rocker arm 13 and the rocker arm shaft 14 can be engaged with each other to swing together.

  Further, the variable valve mechanism 5 has the boss portion 13a of the rocker arm 13 when the rocker arm shaft 14 moves in the shaft axial direction when the cams are switched. Further, through holes 47 and 48 for engaging the stopper ball 46 urged by the plunger 31 so as to face the stopper ball 46 are provided.

  According to this configuration, when the rocker arm shaft 14 slides, the stopper ball 46 fits into and engages with the through holes 47 and 48 of the rocker arm 13 at a predetermined position in the shaft axial direction. Since the rocker arm 13 and the rocker arm shaft 14 are integrated, the rocker arm 13 and the rocker arm shaft 14 can be integrally swung with a simple configuration without using special parts or mechanisms.

The present invention is not limited to the above-described embodiment. For example, the rocker arms 13 and 18 have sliding surfaces for slidingly contacting the cams 11A and 12A, and the valves 6 and 7 are connected via tappet bolts. You may press. Further, the present invention may be applied to various types of reciprocating engines other than parallel four-cylinders (V-type multi-cylinder engine, single-cylinder engine, vertical engine with a crankshaft along the vehicle longitudinal direction, and the like).
And the structure in the said Example is an example of this invention, and it cannot be overemphasized that a various change is possible in the range which does not deviate from the summary of the said invention.

1 engine (internal combustion engine)
5 Variable valve mechanism 6, 7 Intake / exhaust valve (engine valve)
13, 17 Rocker arm 14, 18 Rocker arm shaft 15a, 16a First cam 15b, 16b Second cam 30 Stopper mechanism 31 Plunger 32 Plunger body 32a Tip (one end)
33 Cylinder body 33a Base end (other end, bottom)
33b Tip (intermediate)
34 Energizing member 35 Engaging groove 39 Holding part (holding hole, through hole)
40 Holder 41 Groove 42 Slide groove (lateral groove)
43 Regulation groove (vertical groove)
46 Stopper ball (ball)
47, 48 Through hole (ball engaging part)
50, 60 Plunger stopper T Thickness D1, D1 Depth

Claims (10)

A rocker arm is arranged between one engine valve on the intake or exhaust side of the internal combustion engine and the first and second cams with respect to the engine valve, and according to the movement of the rocker arm shaft that supports the rocker arm in a swingable manner. The rocker arm is slid in the shaft axis direction of the rocker arm shaft to selectively engage the rocker arm with any one of the cams to switch the operation of the engine valve. Mechanism,
A stopper mechanism for positioning the rocker arm on the rocker arm shaft is disposed between the rocker arm and the rocker arm shaft and urges the ball to engage with each other and the ball to be engaged with the ball. In a variable valve mechanism having a plunger,
The ball is held by a holding portion provided on the outer peripheral portion of the rocker arm shaft so that the ball can move to the outer peripheral side of the rocker arm shaft,
The plunger is inserted into an engagement groove formed in the rocker arm shaft at one end thereof, and held in a groove portion provided in the cylinder head,
When the respective cams are switched, the rocker arm and the rocker arm shaft are integrally swung through the ball urged by the plunger, while the cams are not switched. In this case, the variable valve mechanism is characterized in that the integration of the rocker arm and the rocker arm shaft is released and only the rocker arm is swung without the ball being biased by the plunger.   The groove portion is composed of a horizontal groove along the axial direction of the rocker arm shaft and a pair of vertical grooves extending from both ends of the horizontal axis so as to be orthogonal thereto, and the engagement groove is connected to one end portion of the plunger. 2. The rocker arm shaft is inserted so as to be swingable integrally, and a plunger insertion portion of the rocker arm is inserted through an intermediate portion of the plunger so as not to be relatively movable in the shaft axis direction. Variable valve mechanism. The plunger includes a plunger main body constituting one end side thereof, a cylinder body constituting the other end side and inserted through the proximal end side of the plunger main body, and the cylinder body and the plunger main body separated from each other by being accommodated in the cylinder body. An urging member that urges toward the side to be pressed, and the base end portion of the cylinder body presses the inner surface of the groove portion, and the tip end portion of the plunger body urges the ball to engage with the ball And
The variable valve mechanism according to claim 2, wherein each of the groove portions is formed shallower than the horizontal groove.   The variable valve mechanism according to claim 3, wherein the cylinder body has a distal end portion inserted into a plunger insertion portion of the rocker arm and a base end portion held in a groove portion of the cylinder head.   The cylinder body is formed in a bottomed cylindrical shape, and a bottom portion that is a base end portion of the cylinder body is held by the groove portion, and a thickness of the bottom portion is substantially the same as a depth of the groove portion. The variable valve mechanism according to claim 3 or 4.   6. The plunger according to claim 2, wherein each longitudinal groove is provided with a plunger stopper for restricting movement of the plunger during normal operation in which each cam is not switched. Variable valve mechanism. The engagement groove of the rocker arm shaft is formed to have substantially the same width as the outer diameter of the plunger. A plurality of the plungers are arranged in the engagement groove, and a plurality of groove portions corresponding to the plungers are formed in the cylinder head. Provided in
The plunger stopper regulates the movement of the plunger in one of the pair of vertical grooves of each groove, one groove in one groove and the other in the other groove. The variable valve mechanism according to claim 6.   The variable valve mechanism according to any one of claims 1 to 7, wherein a holder made of a separate member is provided on the cylinder head, and the groove is formed in the holder. The holding portion of the rocker arm shaft is a through-hole having a mortar-shaped inner peripheral surface that extends to the outer peripheral side of the rocker arm shaft, and the ball is fitted into the holding portion, and the rocker in a state in which the ball is fitted While the arm shaft is inserted into the rocker arm, the ball is held in the holding portion so as not to fall off,
The holding portion opens into the engagement groove, and when the cams are switched, the rocker arm shaft moves in the shaft axial direction to move the holding portion and the ball in the same position as the plunger in the shaft axial direction. The rocker arm and the rocker arm shaft are engaged via the ball by urging the ball in the holding portion from the inside of the engagement groove toward the outer periphery of the rocker arm shaft by the plunger. The variable valve mechanism according to any one of claims 1 to 8, wherein: The rocker arm is engaged with a stopper ball biased by the plunger so as to face the holding portion and the ball when the rocker arm shaft moves in the shaft axial direction when the cams are switched. The variable valve mechanism according to claim 9, further comprising a ball engaging portion to be combined.

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