JP2007146740A - Variable valve gear, and engine device and vehicle provided with same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small sized low cost variable valve gear capable of optimally changing over a cam according to engine rotation speed. <P>SOLUTION: Since a centrifugal force acting on weights 213 and 216 is small during low speed rotation, rotational operations of the weights 213, 216 are limited. Consequently, lock pins 214, 217 are not engaged with lock pin engagement holes 236b, 236c of a floating cam 235, and the floating cam 235 idles around a cam fixing shaft 244. The centrifugal force acting on the weights 213, 216 becomes large during high speed rotation, the weights 213, 216 rotate around a rotary shaft 215. Consequently, tips of the lock pins 214, 217 are engaged with the lock pin engagement parts 236b, 236c of the floating cam 235. Consequently, the floating cam 235 is fixed in the rotative direction of the variable valve gear 200 by the lock pins 214, 217 during high speed rotation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a variable valve gear that drives a valve of an engine, and an engine device and a vehicle including the same.

  Conventionally, various variable valve mechanisms for controlling intake and exhaust have been developed for the purpose of improving fuel efficiency, reducing harmful substances in exhaust gas, and increasing output in a specific rotation range.

  In order to increase the efficiency of intake and exhaust, it is preferable to switch the intake amount optimally in a low speed range where the engine speed is low and a high speed range where the engine speed is high.

  In general, the space occupied by an engine in a motorcycle is smaller than that of a four-wheeled vehicle or the like. There is also a demand for cost reduction of motorcycles. As a result, a more compact variable valve mechanism is required for motorcycles.

Patent Document 1 proposes an engine valve operating apparatus that switches between a low speed cam and a high speed cam with a simple and compact structure. In this valve operating apparatus, a low speed cam is fixed to the cam shaft, and a high speed cam is provided in parallel with the low speed cam so as to be relatively displaceable on the cam shaft. A control shaft is provided in the camshaft so as to be capable of reciprocating in the axial direction. As the control shaft moves in the axial direction, the high speed cam projects in a direction perpendicular to the cam shaft, and the low speed cam and the high speed cam are switched.
Japanese Patent Laid-Open No. 09-256827

  In the valve operating device of Patent Document 1, switching from a low speed cam to a high speed cam is performed by a hydraulic actuator. Specifically, a control lever is provided so as to be interlocked with the control shaft, and the control lever biased by a spring is moved by a hydraulic actuator. As a result, the control shaft moves in the axial direction and is switched from the low speed cam to the high speed cam.

  However, a large hydraulic pressure is required to move the control lever against the urging force of the spring, the reaction force applied from the valve to the high-speed cam, and the reaction force applied from the valve to the control shaft. For this reason, an oil pump that supplies oil to the hydraulic actuator is required to be larger and more expensive. As a result, production costs increase and miniaturization of the vehicle is impeded.

  An object of the present invention is to provide a variable valve operating apparatus that is compact and low-cost and can optimally switch a cam according to the engine speed.

  (1) A variable valve operating apparatus according to a first aspect of the present invention is a variable valve operating apparatus for driving a valve of an engine, the rotating shaft provided rotatably in conjunction with the rotation of the engine, and the rotating shaft A first cam member that is provided so as to rotate together with the valve and that opens and closes the valve; a second cam member that is provided so as to be rotatable with respect to the rotary shaft and that acts to open and close the valve; A locking member provided so as to be able to shift between a first state in which the two cam members are rotatable with respect to the rotation shaft and a second state in which the second cam member is locked on the rotation shaft; An urging member that generates an urging force that shifts the member to the first state, and a locking member that shifts to the second state against the urging force by the urging member due to the centrifugal force associated with the rotation of the rotating shaft. And a drive member that operates in a first state, and when the locking member is in the first state, Acts of opening and closing cam member of the valve, when the locking member is in the second state is one in which the second cam member acting to open and close the valve.

  In the variable valve operating apparatus according to the first invention, the rotating shaft rotates in conjunction with the rotation of the engine. The first cam member rotates as the rotation shaft rotates. The second cam member is in a state capable of rotating with respect to the rotating shaft when the locking member is in the first state, and is locked with the rotating shaft when the locking member is in the second state. It becomes. The locking member is switched to the first state or the second state according to the number of rotations of the rotating shaft.

  When the rotational speed of the rotary shaft is low, the locking member shifts to the first state by the biasing force generated by the biasing member. Thereby, the second cam member can be rotated with respect to the rotation shaft by the locking member. Therefore, the second cam member does not rotate with the rotation of the rotating shaft. In this case, the first cam member acts to open and close the valve.

  On the other hand, when the rotational speed of the rotating shaft is high, the locking member shifts to the second state against the urging force by the urging member due to the centrifugal force applied to the driving member. Thereby, the second cam member is locked to the rotating shaft. Therefore, the 2nd cam member will be in the state rotated with rotation of a rotating shaft. In this case, the second cam member acts to open and close the valve.

  As described above, the state in which the first cam member acts on the valve and the state in which the second cam member acts on the valve are switched according to the engine speed. Thereby, the first cam member and the second cam member are formed in optimum shapes when the engine is running at low speed and at high speed, respectively, thereby improving fuel efficiency during normal running (medium / low speed running) and exhaust gas. It is possible to reduce harmful substances in the interior and achieve high output during high-speed driving.

  In addition, since the first cam member and the second cam member are switched using the centrifugal force generated by the rotation of the rotating shaft, a drive source by a hydraulic system is unnecessary. Therefore, a small and low-cost variable valve operating device is realized.

  (2) The drive member is rotatably provided from the first position to the second position by centrifugal force accompanying rotation of the rotary shaft, and the locking member is moved from the first position to the second position of the drive member. The urging member is provided so as to be movable in one direction along the rotation axis along with the rotation, the urging member applies an urging force to the driving member so that the driving member is directed to the first position, and the locking member is the driving member. May be in the first state when is in the first position, and may be in the second state when the drive member is in the second position.

  In this case, the urging force by the urging member works so that the driving member moves toward the first position. The centrifugal force accompanying the rotation of the rotation shaft acts so that the drive member rotates from the first position to the second position.

  When the rotational speed of the rotating shaft is low, the urging force applied to the driving member is larger than the centrifugal force, and therefore the driving member is in the first position. Thereby, the locking member is in the first state. Therefore, the second cam member can rotate with respect to the rotation shaft, and the first cam member acts to open and close the valve.

  When the rotational speed of the rotary shaft is high, the centrifugal force applied to the drive member becomes larger than the biasing force, and thus the drive member rotates from the first position to the second position. Thereby, the locking member moves in one direction along the rotation axis, and switches from the first state to the second state. Therefore, the second cam member rotates together with the rotation shaft, and the second cam member acts to open and close the valve.

  Thus, the locking member shifts to the first state or the second state depending on the magnitude of the centrifugal force applied to the driving member. Accordingly, the first cam member and the second cam member can be switched with a simple configuration.

  (3) The locking member has a locking portion, the second cam member has a locked portion that is locked by the locking portion of the locking member, and the locking member is in the first state. In some cases, the locking portion may be disengaged from the locked portion, and the locking portion may lock the locked portion when the locking member is in the second state.

  When the rotational speed of the rotating shaft is low, the locking portion of the locking member is disengaged from the locked portion of the second cam member. Accordingly, the second cam member can be rotated with respect to the rotation shaft. When the rotational speed of the rotating shaft is high, the locking portion of the locking member locks the locked portion of the second cam member. Thereby, the second cam member is fixed to the rotation shaft. In this way, the first cam member and the second cam member can be switched with a simple configuration.

  (4) The locking member includes a rod-shaped member, the locking portion is an end of the rod-shaped member, and the locked portion of the second cam member is a hole into which the end of the rod-shaped member can be fitted. May be.

  When the rotational speed of the rotating shaft is low, the end of the rod-like member is disengaged from the hole of the second cam member. Accordingly, the second cam member can be rotated with respect to the rotation shaft. When the rotational speed of the rotating shaft is high, the end of the rod-shaped member is inserted into the hole of the second cam member. Thereby, the second cam member is fixed to the rotation shaft. In this way, the first cam member and the second cam member can be switched with a simple configuration.

  (5) The locking member is a plurality of rod-shaped members, the locked portion of the second cam member is a plurality of holes into which ends of the plurality of rod-shaped members can be respectively fitted, and the plurality of rod-shaped members are You may arrange | position in a mutually asymmetrical position regarding the center of a rotating shaft.

  In this case, since the plurality of rod-shaped members are respectively inserted into the corresponding plurality of holes, the second cam member is securely fixed to the rotation shaft. Further, since the plurality of rod-shaped members are disposed at positions that are asymmetric with respect to the center of the rotation shaft, each rod-shaped member is reliably inserted into the corresponding hole.

  (6) The variable valve operating apparatus may further include a movement blocking member that blocks the movement of the locking member when the locking member is in at least one of the first state and the second state.

  In this case, since the locking member is securely fixed in the first state or the second state, it is possible to prevent the locking member from becoming unstable due to the reaction force of the valve.

  Further, in a state where the force that the locking member shifts to the first state due to the biasing force generated by the biasing member and the force that the locking member shifts to the second state due to the centrifugal force applied to the drive member balances, It is possible to prevent the locking member from becoming unstable between the first state and the second state. As a result, switching between the first cam member and the second cam member is performed stably, and it is possible to prevent the opening and closing of the valve from becoming unstable.

  (7) The locking member has at least one groove, and the movement preventing member has a fitting portion that can be fitted into the groove when the locking member is in at least one of the first state and the second state. You may have.

  In this case, when the locking member is in at least one of the first state and the second state, the fitting portion of the movement preventing member is fitted into the groove portion of the locking member. Thereby, since the locking member is sufficiently fixed in the first state or the second state, it is possible to reliably prevent the locking member from becoming unstable due to the reaction force of the valve.

  In addition, the state in which the biasing force generated by the biasing member balances the force that shifts the locking member to the first state and the force that causes the driving member to shift the locking member to the second state by the centrifugal force that accompanies the rotation. Thus, it is possible to sufficiently prevent the locking member from becoming unstable between the first state and the second state.

  (8) At least one groove of the locking member when the locking member transitions from the first state to the second state and when the locking member transitions from the second state to the first state The groove portion and the fitting portion may be formed so that the fitting portion of the movement preventing member can be withdrawn from.

  In this case, when the locking member is in the first state or the second state, the fitting portion of the movement preventing member is fitted into the groove portion of the locking member, and the locking member is moved from the first state to the second state. When shifting to the state or when shifting from the second state to the first state, the fitting portion of the movement preventing member is withdrawn from the groove portion of the locking member. Thereby, when the locking member is in the first state or the second state, it is possible to prevent the locking member from becoming unstable due to the reaction force of the valve, and from the first state to the second state. Or the transition from the second state to the first state is performed stably.

  (9) The variable valve operating apparatus includes a first transmission member that moves the valve up and down by swinging in conjunction with the rotation of the first cam member, and a first transmission member that operates in conjunction with the rotation of the second cam member. And a second transmission member that swings the transmission member.

  In this case, the first transmission member swings as the first cam member rotates as the rotation shaft rotates. Thereby, the valve moves up and down.

  Further, in a state where the second cam member is locked to the rotation shaft, the second transmission member swings as the second cam member rotates as the rotation shaft rotates. Thereby, the first transmission member swings and the bubble moves up and down.

  Thus, when the first cam member and the second cam member rotate, the valve moves up and down by the swing of the first transmission member. Thereby, compared with the case where the first transmission member and the second transmission member individually move the valve up and down separately, the valve can be reduced in size, and an uneven load can be prevented from being applied to the valve.

  (10) The first cam member acts to open the valve with the first lift amount in the first state, and the second cam member is a second larger than the first lift amount in the second state. The valve may be opened by a lift amount.

  Here, when the rotational speed of the rotating shaft is low, the first cam member rotates with the rotation of the rotating shaft. Since the second cam member can rotate with respect to the rotation shaft, it does not rotate with the rotation of the rotation shaft. Thereby, the first cam member acts to open the valve by the first lift amount.

  When the rotation speed of the rotation shaft is high, the first cam member rotates with the rotation of the rotation shaft, and the second cam member is engaged with the rotation shaft and rotates. In this case, the first cam member acts to open the valve with the first lift amount, whereas the second cam member opens the valve with the second lift amount larger than the first lift amount. Acts as follows. Thereby, the valve moves up and down by the second lift amount.

  Thus, the lift amount of the valve is switched between the first lift amount and the second lift amount according to the engine speed. As a result, fuel efficiency during normal driving can be improved, harmful substances in the exhaust gas can be reduced, and high output during high-speed driving can be realized.

  (11) The first cam member operates to open the valve at the first operating angle in the first state, and the second cam member is a second larger than the first operating angle in the second state. You may act so that a valve may be opened at an operating angle.

  Here, when the rotational speed of the rotating shaft is low, the first cam member acts to open the valve at the first operating angle.

  When the rotational speed of the rotating shaft is high, the second cam member acts to open the valve at a second operating angle that is larger than the first operating angle.

  Thus, the valve operating angle is switched between the first operating angle and the second operating angle in accordance with the engine speed. As a result, fuel efficiency during normal driving can be improved, harmful substances in the exhaust gas can be reduced, and high output during high-speed driving can be realized.

  (12) The valve may be an intake valve. In this case, the state in which the first cam member acts on the intake valve and the state in which the second cam member acts on the intake valve are switched according to the engine speed. Thereby, the amount of intake air or the timing of intake is adjusted by forming the first cam member and the second cam member in optimum shapes at the time of low and high rotations of the engine, respectively. As a result, fuel efficiency during normal driving can be improved, harmful substances in the exhaust gas can be reduced, and high output during high-speed driving can be realized.

  (13) An engine device according to a second aspect of the present invention includes an engine having a valve and a variable valve operating device for driving the valve of the engine, and the variable valve operating device can rotate in conjunction with the rotation of the engine. A rotary shaft provided on the rotary shaft, a first cam member provided to rotate together with the rotary shaft and acting to open and close the valve, and rotatably provided to the rotary shaft so as to open and close the valve It is possible to shift to a second cam member that acts, a first state in which the second cam member is rotatable with respect to the rotating shaft, and a second state in which the second cam member is locked to the rotating shaft. A locking member provided, a biasing member that generates a biasing force that causes the locking member to shift to the first state, and a locking against the biasing force by the biasing member due to the centrifugal force associated with the rotation of the rotating shaft A drive member that operates to move the member to the second state; The first cam member acts to open and close the valve when the locking member is in the first state, and the second cam member opens and closes the valve when the locking member is in the second state. It acts on.

  In the engine device according to the second invention, the valve of the engine is driven by the variable valve operating device.

  In the variable valve gear, the rotation shaft rotates in conjunction with the rotation of the engine. The first cam member rotates as the rotation shaft rotates. The second cam member is in a state capable of rotating with respect to the rotating shaft when the locking member is in the first state, and is locked with the rotating shaft when the locking member is in the second state. It becomes. The locking member is switched to the first state or the second state according to the number of rotations of the rotating shaft.

  When the rotational speed of the rotary shaft is low, the locking member shifts to the first state by the biasing force generated by the biasing member. Thereby, the second cam member can be rotated with respect to the rotation shaft by the locking member. Therefore, the second cam member does not rotate with the rotation of the rotating shaft. In this case, the first cam member acts to open and close the valve.

  On the other hand, when the rotational speed of the rotating shaft is high, the locking member shifts to the second state against the urging force by the urging member due to the centrifugal force applied to the driving member. Thereby, the second cam member is locked to the rotating shaft. Therefore, the 2nd cam member will be in the state rotated with rotation of a rotating shaft. In this case, the second cam member acts to open and close the valve.

  As described above, the state in which the first cam member acts on the valve and the state in which the second cam member acts on the valve are switched according to the engine speed. As a result, the first cam member and the second cam member are formed into optimum shapes when the engine is running at low and high speeds, respectively, thereby improving fuel efficiency during normal driving and reducing harmful substances in the exhaust gas. In addition to being able to reduce, it is possible to achieve high output during high-speed traveling.

  In addition, since the first cam member and the second cam member are switched using the centrifugal force generated by the rotation of the rotating shaft, a drive source by a hydraulic system is unnecessary. Therefore, a small and low-cost variable valve operating device is realized.

  (14) A vehicle according to a third invention includes the engine device according to the second invention, a drive wheel, and a transmission mechanism that transmits power generated by the engine device to the drive wheel.

  In the vehicle according to the third aspect of the invention, the power generated by the engine device according to the second aspect of the invention is transmitted to the drive wheels by the transmission mechanism, and the drive wheels are driven. Here, in the engine device, the valve of the engine is driven by the variable valve operating device.

  In this case, in the engine device according to the second aspect of the invention, the state in which the first cam member acts on the valve and the state in which the second cam member acts on the valve are switched according to the engine speed. . As a result, the first cam member and the second cam member are formed into optimal shapes when the engine is running at a low speed and at a high speed, respectively, thereby improving fuel efficiency during normal driving and reducing harmful substances in the exhaust gas. In addition to being able to reduce, it is possible to achieve high output during high-speed traveling.

  In addition, since the first cam member and the second cam member are switched using the centrifugal force generated by the rotation of the rotating shaft, a drive source by a hydraulic system is unnecessary. Therefore, a small and low-cost variable valve operating device is realized.

  According to the present invention, the state in which the first cam member acts on the valve and the state in which the second cam member acts on the valve are switched according to the engine speed. As a result, the first cam member and the second cam member are formed into optimal shapes when the engine is running at a low speed and at a high speed, respectively, thereby improving fuel efficiency during normal driving and reducing harmful substances in the exhaust gas. In addition to being able to reduce, it is possible to achieve high output during high-speed traveling. In addition, since the first cam member and the second cam member are switched using the centrifugal force generated by the rotation of the rotating shaft, a drive source by a hydraulic system is unnecessary. Therefore, a small and low-cost variable valve operating device is realized.

  Hereinafter, a variable valve operating apparatus according to an embodiment of the present invention, an engine apparatus including the same, and a vehicle will be described. In the present embodiment, a small motorcycle will be described as a vehicle.

(1) Configuration of Vehicle FIG. 1 is a schematic diagram of a motorcycle according to an embodiment of the present invention.

  In the motorcycle 100, the head pipe 3 is provided at the front end of the main body frame 6. A front fork 2 is provided on the head pipe 3 so as to be swingable in the left-right direction. A front wheel 1 is rotatably supported at the lower end of the front fork 2. A handle 4 is attached to the upper end of the head pipe 3.

  An engine 7 is held at the center of the main body frame 6. A fuel tank 8 is provided at the top of the engine 7, and a seat 9 is provided behind the fuel tank 8.

  A rear arm 10 is connected to the main body frame 6 so as to extend rearward of the engine 7. The rear arm 10 rotatably holds the rear wheel 11 and the rear wheel driven sprocket 12. An exhaust pipe 13 is connected to the engine 7. A muffler 14 is attached to the rear end of the exhaust pipe 13.

  A rear wheel drive sprocket 15 is attached to the drive shaft 26 of the engine 7. The rear wheel drive sprocket 15 is connected to the rear wheel driven sprocket 12 of the rear wheel 11 via a chain 16.

  The engine 7 is provided with a variable valve operating device. Hereinafter, the variable valve operating apparatus according to the present embodiment will be described.

(2) Outline of Variable Valve Operating Device FIG. 2 is a diagram for explaining the outline of the variable valve operating device according to one embodiment of the present invention. FIG. 2A shows a schematic top view of a variable valve operating device provided inside the engine 7, and FIG. 2B shows a schematic side view of the variable valve operating device provided inside the engine 7. Yes.

  As shown in FIGS. 2A and 2B, the variable valve gear 200 is provided in the cylinder head 7 </ b> S of the engine 7. The variable valve operating apparatus 200 includes a cam driven sprocket 220, an intake high cam 237, an intake low cam 241 and an exhaust cam 242.

  As the piston 21 reciprocates in the cylinder 20, the crankshaft 23 rotates, and the cam drive sprocket 24 provided on the crankshaft 23 rotates.

  The rotational force of the cam drive sprocket 24 is transmitted to the cam driven sprocket 220 of the variable valve operating apparatus 200 via the chain 25. Thereby, the variable valve apparatus 200 rotates.

  In variable valve operating apparatus 200, switching between intake high cam 237 and intake low cam 241 is performed in accordance with the rotation speed of engine 7 and changes in the rotation speed (increase and decrease in the rotation speed). As a result, the lift amount of an intake valve, which will be described later, changes, and the intake amount to the cylinder 20 changes. The rotational speed of the engine 7 means the rotational speed of the engine 7.

(3) Configuration of Variable Valve Operating Device Details of the configuration of the variable valve operating device 200 will be described. 3 to 5 are assembled perspective views for explaining the structure of the variable valve operating apparatus 200. 3 to 5, as indicated by arrows X, Y, and Z, three directions orthogonal to each other are defined as an X direction, a Y direction, and a Z direction.

  The variable valve operating apparatus 200 is roughly divided into a lock pin holding mechanism 210 (see FIG. 3), a cam driven sprocket 220 (see FIG. 4), a lock pin locking mechanism 230 (see FIG. 4), and an idle cam portion 235 (see FIG. 4). 5) and a camshaft 240 (see FIG. 5).

  FIG. 3 shows an assembled perspective view of the lock pin holding mechanism 210. As shown in FIG. 3, the lock pin holding mechanism 210 has a support member 211 parallel to the XZ plane. A through hole 211G is formed at the center of the support member 211.

  On one side of the upper end portion and the lower end portion of the support member 211, projection pieces 211a and 211b bent so as to extend in the Y direction are formed. Between the protruding piece 211a and the protruding piece 211b, a spring holding piece 212a bent in a U-shape and a protruding piece 211c extending in the X direction are formed on one surface side of the support member 211.

  On the other side of the upper end portion and the lower end portion of the support member 211, projection pieces 211d and 211e bent so as to extend in the Y direction are formed. Between the protruding piece 211d and the protruding piece 211e, a protruding piece 211f extending in the X direction and a spring holding piece 212b bent in a U-shape on one surface side of the support member 211 are formed.

  Through holes 211A to 211F are formed in the projecting pieces 211a to 211f, respectively, and through holes 212A and 212B are formed in the holding pieces 212a and 212b, respectively.

  Concave notches 211H and 211I are formed in the center of the upper end and the center of the lower end of the support member 211, respectively.

  The weight 213 includes a weight main body 213a, a plate-like extension 213d, two cylindrical portions 213e, and two hook portions 213f. The weight main body 213a has a substantially rectangular parallelepiped shape extending in the X direction.

  The extension 213d is formed so as to extend in the Y direction from the upper surface of the weight body 213a. The two cylindrical portions 213e are formed along the X direction at both ends of the extension portion 213d in the X direction.

  The two hook portions 213f extend from the center portion of the extension portion 213d in the X direction so as to incline below the extension portion 213d. The tips of the two hook portions 213f are curved in a partial cylindrical shape.

  Lock pins 214 extending in the Y direction are attached to the two hook portions 213f. In the vicinity of one end of the lock pin 214, a support pin 214t extending in the X direction is formed. By attaching the support pin 214t to the hook portion 213f, the lock pin 214 is rotatably held by the weight 213. A part of the lock pin 214 can come into contact with the weight body 213.

  On the outer peripheral surface near the other end of the lock pin 214, an annular groove 214a and a groove 214b are formed in parallel.

  A rotating shaft 215 is inserted into the cylindrical portion 213e of the weight 213. Thereby, the rotating shaft 215 holds the weight 213 in a rotatable manner. In this state, both ends of the rotation shaft 215 are inserted into the through holes 211 </ b> A and 211 </ b> D of the support member 211. Thereby, the weight 213 is rotatably held on the support member 211. Further, the lock pin 214 is disposed so as to pass through the notch 211H of the support member 211.

  The weight 216 has the same structure as the weight 213. When the lock pin holding mechanism 210 is assembled, the weight 216 is disposed so as to face the weight 213.

  In FIG. 3, the weight body 216 a of the weight 216, the extension part 216 d, the two cylindrical parts 216 e and the two hook parts 216 f are the weight body 213 a, the extension part 213 d of the weight 213, the two cylindrical parts 213 e and the two hooks. It corresponds to the part 213f.

  The lock pin 217 has the same structure as the lock pin 214. The groove portions 217a and 217b of the lock pin 217 correspond to the groove portions 214a and 214b. The support pin 217t corresponds to the support pin 214t.

  A rotating shaft 218 is inserted into the cylindrical portion 216e of the weight 216. Thereby, the rotating shaft 218 holds the weight 216 in a rotatable manner. In this state, both ends of the rotation shaft 218 are inserted into the through holes 211B and 211E of the support member 211. Thereby, the weight 216 is rotatably held on the support member 211. Further, the lock pin 217 is arranged so as to pass through the notch 211I of the support member 211.

  The lock pins 214 and 217 are arranged so as to be perpendicular to the support member 211. The distance between the through hole 211G of the support member 211 and the lock pin 214 is smaller than the distance between the through hole 211G and the lock pin 217.

  Screws 219 are inserted into the two through holes 211C and 211F of the two protruding pieces 211c and 211f of the support member 211, respectively.

  FIG. 4 is an assembly perspective view of the lock pin holding mechanism 210, the cam driven sprocket 220, and the lock pin locking mechanism 230. The cam driven sprocket 220 is disposed so as to be parallel to the XZ plane, and the lock pin locking mechanism 230 is disposed so that the axis J thereof is parallel to the Y direction.

  Here, in the lock pin holding mechanism 210, one end of the spring S1 is locked in the through hole of the protruding portion (not shown) of the weight 213, and the other end is locked in the through hole 212B of the spring holding piece 212b. . One end of the spring S2 is locked in a through hole of a protruding portion (not shown) of the weight 216, and the other end is locked in a through hole 212A of the spring holding piece 212a.

  The cam driven sprocket 220 has a plurality of through holes 220a to 220e. The through hole 220a formed at the center of the cam driven sprocket 220 has a larger diameter than the other through holes 220b to 220e.

  The through holes 220a, 220b, and 220c are arranged on the same straight line parallel to the Z direction, and the through hole 220b and the through hole 220c have the same diameter. The distance between the through hole 220a and the through hole 220b is smaller than the distance between the through hole 220a and the through hole 220c. Further, the through hole 220d and the through hole 220e are formed at symmetrical positions with respect to the through hole 220a, and have the same diameter.

  The lock pin locking mechanism 230 is formed of a cylindrical rotation shaft 231 and a disk-shaped lock plate storage member 232.

  The lock pin locking mechanism 230 is formed with through holes 230H, 230b, and 230c. The through hole 230 </ b> H is formed in the shaft center J of the lock pin locking mechanism 230. That is, the through hole 230 </ b> H is formed from the center of the end surface of the rotating shaft 231 to the center of the end surface of the lock plate storage member 232. The through holes 230H, 230b, and 230c are arranged on the same straight line parallel to the Z direction, and the through hole 230b and the through hole 230c have the same diameter. The distance between the through hole 230a and the through hole 230b is shorter than the distance between the through hole 230a and the through hole 230c.

  Further, screw screw holes 230d and 230e are formed on the end surface of the rotation shaft 231 of the lock pin locking mechanism 230. The screw screw holes 230d and 230e are formed at symmetrical positions with respect to the through hole 230H and have the same diameter. The screw screw holes 230d and 230e are threaded. Further, a stepped portion 231 a is formed on the outer peripheral surface of the rotating shaft 231.

  A slit-like lock plate insertion port 232A and a substantially circular spring insertion port 232B are formed on the outer peripheral surface of the lock plate housing member 232 of the lock pin locking mechanism 230. The lock plate insertion port 232A communicates with a lock plate storage space 232b (FIG. 6 described later) formed inside the lock plate storage member 232, and the spring insertion port 232B is a spring storage space 232c formed inside the lock plate storage member 232. It communicates with (FIG. 6 mentioned later).

  A plate-like lock plate 233 is inserted into the lock plate storage space 232b (FIG. 6) in the lock plate storage member 232 from the lock plate insertion port 232A. The spring 234 is inserted into the spring storage space 232c (FIG. 6) in the lock plate storage member 232 from the spring insertion port 232B.

  The lock plate 233 includes a substantially rectangular support plate 233a, a long lock pin locking portion 233b, and a long lock pin locking portion 233c. The lock pin engaging portion 233b extends in one direction along one side of the support plate 233a, and the lock pin engaging portion 233c extends obliquely outward from one corner of the support plate 233a and is parallel to the lock pin engaging portion 233b. It is bent to become. A through hole 233A is formed at the center of the support plate 233a.

  A columnar member 234 a is attached to one end of the spring 234 to facilitate attachment to and removal from the lock pin locking mechanism 230.

  Here, the arrangement of the lock plate 233 and the spring 234 in the lock plate housing member 232 will be described with reference to FIG.

  FIG. 6 is an XZ plane sectional view of the lock plate storage member 232 in a state where the lock plate 233 and the spring 234 are inserted.

  As shown in FIG. 6, a pin 233 d is inserted into the through hole 233 A of the lock plate 233. Accordingly, the lock plate 233 is held so as to be swingable within the lock plate storage space 232 b of the lock plate storage member 232.

  In addition, the spring 234 is inserted into the spring housing space 232 c in the Z direction, and the lower end portion of the spring 234 comes into contact with the upper end portion of the lock pin engaging portion 233 b of the lock plate 233. Thereby, the lock plate 233 is biased downward.

  The lower end portion of the lock pin engaging portion 233c of the lock plate 233 is fitted into the groove portion 214a (FIG. 3) or the groove portion 214b (FIG. 3) of the lock pin 214 inserted into the lock plate housing member 232 in the Y direction. The lower end portion of the lock pin engaging portion 233b of the lock plate 233 is fitted into the groove portion 217a (FIG. 3) or the groove portion 217b (FIG. 3) of the lock pin 217 inserted into the lock plate housing member 232 in the Y direction.

  Thereby, the movement of the lock pins 214 and 217 in the Y direction is restricted by the lock plate 233. Details will be described later.

  Here, as shown in FIG. 4, the relative positions of the through holes 220 d and 220 e with respect to the through hole 220 a of the cam driven sprocket 220 are screw-screws with reference to the through hole 230 H of the lock pin locking mechanism 230. This is the same as the relative positions of the joint holes 230d and 230e. The diameters of the through holes 230d and 230e are equal to the diameters of the screw screw holes 220d and 220e.

  When the lock pin holding mechanism 210, the cam driven sprocket 220 and the lock pin locking mechanism 230 are assembled, the position of the through hole 220d of the cam driven sprocket 220 and the position of the through hole 230d of the lock pin locking mechanism 230 are determined. In addition, in a state where the position of the through hole 220e of the cam driven sprocket 220 and the position of the through hole 230e of the lock pin locking mechanism 230 are matched, the screw 219 of the lock pin holding mechanism 210 is screwed into each.

  As a result, the lock pin holding mechanism 210 is fixed to one surface of the cam driven sprocket 220, and the lock pin locking mechanism 230 is fixed to the other surface of the cam driven sprocket 220.

  At this time, the lock pin 214 is inserted into the through hole 220b of the cam driven sprocket 220 and the through hole 230b of the lock pin locking mechanism 230, and the lock pin 217 is inserted into the through hole 220c of the cam driven sprocket 220 and the lock pin locking mechanism. 230 is inserted into the through hole 230c. When the weights 213 and 216 rotate, the lock pins 214 and 217 protrude from the end surface of the lock pin engaging mechanism 230 on the lock plate storage member 232 side, and the lock pins 214 and 217 enter the lock pin engaging mechanism 230. The stored state is switched. Details will be described later.

  FIG. 5 shows an assembled perspective view of the structure assembled as shown in FIG. 4 (hereinafter referred to as an assembled structure), the floating cam portion 235 and the camshaft 240. Note that the axial center J of the floating cam portion 235 and the camshaft 240 is arranged to be parallel to the Y direction.

  The idle cam portion 235 is formed of an intake high cam 237 having a lock pin fitting portion 236 and a cam nose 237A. A through hole 235H is formed in the portion of the axis J of the floating cam portion 235. That is, the through hole 235 </ b> H is formed from the center of the end surface of the lock pin fitting portion 236 to the center of the end surface of the intake high cam 237.

  Lock pin fitting holes 236b and 236c are formed in the lock pin fitting portion 236 of the floating cam portion 235. The lock pin fitting holes 236b and 236c and the through hole 235H are arranged on the same straight line parallel to the Z direction, and the lock pin fitting hole 236b and the lock pin fitting hole 236c have the same diameter. The distance between the through hole 235H and the lock pin fitting hole 236b is shorter than the distance between the through hole 235H and the lock pin fitting hole 236c.

  The camshaft 240 includes an intake low cam 241 having a cam nose 241A, an exhaust cam 242 having a cam nose 242A, a stepped portion 243, a cam fixing shaft 244, and a protruding shaft 245.

  The cam shaft 240 has a cam fixing shaft 244 extending in the Y direction on one end side in the Y direction, a step 243, an intake low cam 241 and an exhaust cam 242 in the center, and extending in the Y direction on the other end side. A protruding shaft 245 is provided. A screw hole 240H is formed at the end of the cam fixing shaft 244.

  The length of the cam nose 237A of the intake high cam 237 of the floating cam portion 235 is larger than the length of the cam nose 241A of the intake low cam 241.

  At the time of assembling the assembly structure, the floating cam portion 235, and the camshaft 240, the floating cam portion 235 and the camshaft 240 are attached to the lock plate storage member 232 of the assembly structure.

  In this case, the cam fixing shaft 244 of the camshaft 240 is inserted into the through hole 235H of the floating cam portion 235 and the through hole 230H (FIG. 4) of the lock pin locking mechanism 230. Thereby, the idle cam part 235 is rotatably held by the camshaft 240.

  Further, the sprocket screw hole 240H of the cam fixing shaft 244 faces the through hole 220a (FIG. 4) of the cam driven sprocket 220 in the through hole 235H (FIG. 5) of the lock pin locking mechanism 230. Further, the through hole 220a (FIG. 4) of the cam driven sprocket 220 and the through hole 211G of the lock pin holding mechanism 210 face each other.

  In this state, the screw 250 is screwed into the screw hole 240H of the cam fixing shaft 244 from the through hole 211G of the lock pin holding mechanism 210. As a result, the camshaft 240 is fixed to the cam driven sprocket 220. Thereby, the variable valve apparatus 200 is completed.

  The rotation shaft 231 and the lock plate storage member 232 of the lock pin locking mechanism 230 may be formed integrally or may be formed individually. Further, the intake low cam 241, the exhaust cam 242, the stepped portion 243, the cam fixing shaft 244 and the protruding shaft 245 of the camshaft 240 may be formed integrally or may be formed individually.

  Further, although not shown in FIG. 5, a fixing mechanism that restricts the rotation of the camshaft 240 relative to the cam driven sprocket 220 may be provided at a connection portion between the cam fixing shaft 244 and the through hole 220 a (FIG. 4). .

  In this fixing mechanism, for example, a protrusion is provided at the tip of the cam fixing shaft 244 of the camshaft 240, and a groove that can be fitted to the protrusion of the cam fixing shaft 244 in the through hole 220a (FIG. 4) of the cam driven sprocket 220. It may be realized by providing.

(4) Operation of Variable Valve Operating Device In the variable valve operating device 200 having the configuration of FIGS. 3 to 6, the state is switched according to the engine speed. Next, switching of the state of the variable valve apparatus 200 will be described. In the following description, a case where the rotational speed of the engine 7 (see FIGS. 1 and 2) is higher than a predetermined value is referred to as high rotation time, and a case where the engine speed is lower than the predetermined value is referred to as low rotation time. The rotational speed of the cam fixing shaft 244 is half of the rotational speed of the engine 7. The rotation speed of the cam fixed shaft 244 at the time of switching between the low rotation speed and the high rotation speed is called a threshold value.

  First, when the engine 7 is operated, the variable valve apparatus 200 (see FIGS. 3 to 6) rotates. Thereby, a centrifugal force due to rotation is applied to the weights 213 and 216 of the variable valve apparatus 200 in addition to the urging forces due to the springs S1 and S2. The magnitude of the centrifugal force applied to the weights 213 and 216 varies depending on the rotation speed of the variable valve apparatus 200. The state of the variable valve apparatus 200 is switched using the change in the magnitude of the centrifugal force.

  FIG. 7 is a cross-sectional view showing the state of the variable valve apparatus 200 during low rotation, and FIG. 8 is a cross-sectional view showing the state of the variable valve apparatus 200 during high rotation.

  7 and 8, two directions orthogonal to each other are defined as a Y direction and a Z direction, as indicated by arrows Y and Z. The direction in which the arrow is directed is the + direction, and the opposite direction is the-direction.

  As shown in FIG. 7, a biasing force in the −Z direction by the spring S <b> 1 is applied to the weight 213, and a centrifugal force in the + Z direction due to the rotation of the variable valve apparatus 200 is applied to the weight 213. At the time of low rotation (when the rotation speed of the cam fixing shaft 244 is lower than the threshold value), the centrifugal force applied to the weight 213 is small, so the weight 213 rotates around the rotation shaft 215 by the biasing force of the spring S1. Is limited.

  The lock pin engaging portion 233 c of the lock plate 233 is fitted in the groove portion 214 a of the lock pin 214. The lock plate 233 is urged in the −Z direction by a spring 234 (see FIGS. 4 and 6). Therefore, the movement of the lock pin 214 in the + Y direction is limited.

  Thereby, the lock pin 214 is fixed in a state in which the tip thereof is housed in the lock pin locking mechanism 230.

  Similarly, a biasing force in the + Z direction by the spring S <b> 2 (FIGS. 3 to 5) is applied to the weight 216, and a centrifugal force in the −Z direction due to the rotation of the variable valve apparatus 200 is applied. Since the centrifugal force applied to the weight 216 is small at the time of low rotation, the rotation operation of the weight 216 around the rotation shaft 218 is limited by the biasing force of the spring S2.

  Since the lock pin engaging portion 233b of the lock plate 233 is fitted in the groove portion 217a of the lock pin 217, and the lock plate 233 is biased in the −Z direction by the spring 234, the movement of the lock pin 217 in the + Y direction is Limited.

  Thereby, the lock pin 217 is fixed in a state in which the tip thereof is accommodated in the lock pin locking mechanism 230.

  Thus, the lock pins 214 and 217 are not fitted into the lock pin fitting holes 236b and 236c of the floating cam portion 235, and the floating cam portion 235 rotates around the cam fixing shaft 244.

  On the other hand, as shown in FIG. 8, during a high rotation (when the rotation speed of the cam fixing shaft 244 exceeds the threshold value), the centrifugal force in the + Z direction applied to the weight 213 is -Z by the spring S1. The weight 213 is larger than the urging force in the direction, and the weight 213 acts to rotate in the direction of the arrow M1 about the rotation shaft 215.

  Along with this, a force is exerted on the lock pin 214 to move in the + Y direction. As a result, the lock pin engaging portion 233 c of the lock plate 233 is disengaged from the groove portion 214 a of the lock pin 214. As a result, when the position of the lock pin fitting hole 236b of the floating cam portion 235 and the position of the tip of the lock pin 214 are combined, the tip of the lock pin 214 protrudes from one surface of the lock pin locking mechanism 230, It is fitted to the lock pin fitting portion 236b of the idle cam portion 235. At this time, the lock pin engaging portion 233 c of the lock plate 233 is fitted into the groove portion 214 b of the lock pin 214. Thereby, the movement of the lock pin 214 in the −Y direction is restricted. Therefore, the lock pin 214 is fixed in a state of being fitted to the lock pin fitting portion 236b of the floating cam portion 235.

  Similarly, the centrifugal force in the −Z direction applied to the weight 216 is larger than the urging force in the + Z direction by the spring S2 (FIGS. 3 to 5), and the weight 216 is centered on the rotation shaft 218 in the direction of the arrow M2. The force that tries to rotate is working.

  Along with this, a force to move in the + Y direction acts on the lock pin 217. As a result, the lock pin engaging portion 233b of the lock plate 233 is disengaged from the groove portion 217a of the lock pin 217. As a result, when the position of the lock pin fitting hole 236c of the floating cam portion 235 and the position of the distal end portion of the lock pin 217 are aligned, the distal end of the lock pin 217 protrudes from one surface of the lock pin engaging mechanism 230, The cam portion 235 is fitted into the lock pin fitting portion 236c. At this time, the lock pin engaging portion 233b of the lock plate 233 is fitted into the groove portion 217b of the lock pin 217. Thereby, the movement of the lock pin 214 in the −Y direction is restricted. Accordingly, the lock pin 217 is fixed in a state of being fitted in the lock pin fitting hole 236c of the floating cam portion 235.

  Thus, at the time of high rotation, the idle cam portion 235 is fixed with respect to the rotation direction of the variable valve apparatus 200 by the lock pins 214 and 217.

  3 to 5, the lock pin 214 and the lock pin 217, and the lock pin fitting hole 236b and the lock pin fitting hole 236c have different distances from the cam fixing shaft 244, respectively. . Thereby, the idle cam part 235 is always fixed with the same phase with respect to a rotating shaft, without being fixed in the inverted state.

  Here, generally, when such a switching mechanism using centrifugal force is provided, the centrifugal force applied to the weights 213 and 216 and the biasing force of the springs S1 and S2 in a certain rotational speed region of the engine 7 A balanced state occurs. If this state continues, the movement of the lock pins 214 and 217 becomes unstable.

  Therefore, in the present embodiment, movement of the lock pins 214 and 217 is restricted by the lock plate 233. Thereby, the movement of the lock pins 214 and 217 is performed stably. Details of the operation will be described below.

  FIG. 9 is a diagram for explaining the details of the operation of the lock plate 233 and the lock pins 214 and 217 of FIGS. 7 and 8. FIG. 9A shows the state of the lock plate 233 and the lock pins 214 and 217 during the low rotation (the state shown in FIG. 7), and FIG. 9C shows the lock plate 233 and the lock pin during the high rotation. FIG. 9B shows the state of 214 and 217 (the state shown in FIG. 8), and FIG. 9B shows the lock plate 233 and the lock pin 214 in the middle of the transition from the state of FIG. 9A to the state of FIG. , 217 are shown.

  In FIG. 9 as well, the Y direction and the Z direction are defined as in FIGS. 9 shows only the lock pin 214 of the lock pin 214 and the lock pin 217, and shows only the lock pin engagement portion 233c of the lock pin engagement portion 233c and the lock pin engagement portion 233b of the lock plate 233. . The relationship between the lock pin 217 and the lock pin engaging portion 233b is the same as the relationship between the lock pin 214 and the lock pin engaging portion 233c.

  As shown in FIG. 9, the cross sections of the grooves 214a and 214b of the lock pin 214 are V-shaped. The cross section of the lower end portion of the lock pin engaging portion 233c is formed in a tapered shape that is complementary to the cross sectional shape of the groove portions 214a and 214b.

  When shifting from the low rotation state of FIG. 9 (a) to the high rotation state of FIG. 9 (c), as shown in FIG. 9 (b), the lower end of the lock pin engaging portion 233c. However, it is lifted in the + Z direction along the inclined surface of the groove 214a of the lock pin 214 and is released from the groove 214a. As a result, the lock pin 214 moves in the + Y direction. The transition from the high rotation state to the low rotation state is performed in the reverse order.

  As described above, by restricting the movement of the lock pin 214 by the lock plate 233, the movement force of the lock pin 214 in the + Y direction is not sufficiently increased when the engine speed is shifted from the low state to the high state. The lock pin 214 does not move. Specifically, when the centrifugal force in the + Z direction applied to the weight 213 becomes larger than a certain value by the biasing force in the −Z direction by the spring S1 (the rotational speed of the cam fixing shaft 244 is greater than the threshold value). The lock pin 214 moves when the value of the lock pin 214 is higher than a certain value.

  Further, when the engine speed is shifted from a high state to a low state, the lock pin 214 does not move unless the moving force of the lock pin 214 in the + Y direction becomes sufficiently large. Specifically, when the centrifugal force in the + Z direction applied to the weight 213 becomes smaller than a certain value by the biasing force in the −Z direction by the spring S1 (the rotational speed of the cam fixing shaft 244 is lower than the threshold value). The lock pin 214 moves when the value is also lower than a certain value.

  This prevents the movement of the lock pins 214 and 217 from becoming unstable in the state where the centrifugal force applied to the weights 213 and 216 and the biasing force of the springs S1 and S2 are balanced.

(5) Attachment of Variable Valve Operating Device to Engine FIG. 10 is a cross-sectional view showing a state where the variable valve operating device 200 is attached to the engine 7. In FIG. 10, as indicated by arrows X, Y, and Z, three directions orthogonal to each other are defined as an X direction, a Y direction, and a Z direction.

  As shown in FIG. 10, a space for mounting the variable valve apparatus 200 is provided in the upper part of the cylinder head 7S.

  Bearings B <b> 1 and B <b> 2 are attached to the outer peripheral portion of the rotating shaft 231 and the outer peripheral portion of the protruding shaft 245 of the variable valve apparatus 200, respectively.

  Inside the cylinder head 7S, one end surface perpendicular to the Y direction of the bearing B1 contacts the internal contact surface BH1 of the cylinder head 7S. Further, one end surface of the bearing B2 perpendicular to the Y direction contacts the internal contact surface BH2 of the cylinder head 7S. A part of the other end surface perpendicular to the Y direction of the bearing B1 is brought into contact with the fixed plate BH3 by the cylinder head 7S. Thereby, the variable valve apparatus 200 is rotatably fixed inside the cylinder head 7S.

  An intake high cam rocker arm 330, an intake low cam rocker arm 340, and an exhaust rocker arm 350 are provided on the upper part of the variable valve apparatus 200. The intake high cam rocker arm 330 is in contact with the intake high cam 237 of the variable valve apparatus 200, the intake low cam rocker arm 340 is in contact with the intake low cam 241 of the variable valve apparatus 200, and the exhaust cam rocker arm 350 is in the variable valve apparatus 200. It contacts the exhaust cam 242.

  A side cover SC is attached to the cylinder head 7S so as to cover the lock pin holding mechanism 210 side of the variable valve apparatus 200. A chain 25 is hung on the cam driven sprocket 220.

(6) Valve Drive by Variable Valve Operating Device FIG. 11 is a top view showing the arrangement of the variable valve operating device 200, the intake high cam rocker arm 330, the intake low cam rocker arm 340, and the exhaust rocker arm 350 of FIG. 12 is a cross-sectional view taken along line RR of the cylinder head 7S of FIG. 11 and 12, the X direction, the Y direction, and the Z direction are defined as in FIG.

  As shown in FIG. 11, the variable valve gear 200 is mounted in the cylinder head 7S by bearings B1 and B2. The intake high cam rocker arm 330 and the intake low cam rocker arm 340 are arranged in parallel on one side of the variable valve operating apparatus 200 and are rotatably held by a shaft 341 at the respective central portions. One end of the intake high cam rocker arm 330 extends to bend to a position above the intake high cam 237 (Z direction), and one end of the intake low cam rocker arm 340 is bent to a position above the intake low cam 241 (Z direction). It extends.

  The exhaust cam rocker arm 350 is disposed on the other side of the variable valve apparatus 200 and is rotatably held by a shaft 351 at the center thereof. One end of the exhaust cam rocker arm 350 extends to a position above the exhaust cam 242 (Z direction).

  As shown in FIG. 12, the intake low cam rocker arm 340 includes a cam receiving portion 340T, an arm 340R, an adjuster 342, and a nut 343.

  One end of the arm 340R in the X direction is provided with a cam receiving portion 340T that comes into contact with the intake low cam 241, and an adjuster 342 is attached to the other end with a nut 343.

  A pin 345 extending in the Y direction is attached to the arm 340 </ b> R near the adjuster 342 so as to protrude below the intake high cam rocker arm 330.

  The intake high cam rocker arm 330 includes a cam receiving portion (not shown), an arm 330R, an adjuster 332, and a nut 333.

  One end of the arm 330 </ b> R in the X direction is provided with a cam receiving portion that contacts the intake high cam 237, and an adjuster 332 is attached to the other end with a nut 333. The adjuster 332 of the intake high cam rocker arm 330 contacts the upper portion of the pin 345 of the intake low cam rocker arm 340.

  As the intake low cam 241 rotates in the direction of the arrow Q2, the cam receiver 340T moves up and down. As a result, the arm 340R rotates about the shaft 341, and the adjuster 342 moves up and down. Similarly, the cam receiving portion 330T moves up and down as the intake high cam 237 rotates in the direction of the arrow Q2. Thereby, the arm 330R rotates about the shaft 341, and the adjuster 332 moves up and down.

  An intake valve 344 is positioned below the adjuster 342 of the intake low cam rocker arm 340. A stem end 344 a at the upper end of the intake valve 344 is in contact with the adjuster 342. The intake valve 344 is provided with a valve spring 347. The valve spring 347 biases the intake valve 344 upward.

  As shown in FIG. 5, the length of the cam nose 237A of the intake high cam 237 is larger than the length of the cam nose 241A of the intake low cam 241. Thus, the downward movement distance of the adjuster 332 accompanying the rotation of the intake high cam 237 is larger than the downward movement distance of the adjuster 342 accompanying the rotation of the intake low cam 241. When the intake high cam 237 is rotating, the downward moving force of the intake high cam rocker arm 330 is transmitted to the intake low cam rocker arm 340 via the pin 345.

  Here, in the present embodiment, as shown in FIG. 7, the intake high cam 237 at the time of low rotation is rotatable with respect to the cam fixing shaft 244 of the camshaft 240. Therefore, the rotational force of the cam fixing shaft 244 is not transmitted to the intake high cam 237. On the other hand, as shown in FIG. 8, the intake high cam 237 during high rotation is fixed to the cam fixing shaft 244 by the lock pins 214 and 217. Therefore, the rotational force of the cam fixing shaft 244 is transmitted to the intake high cam 237.

  That is, at the time of low rotation, the intake high cam rocker arm 330 is not driven by the intake high cam 237. Therefore, the adjuster 342 of the intake low cam rocker arm 340 moves up and down by the rotation of the intake low cam 241 and the intake valve 344 performs an up and down operation (lift operation). As a result, the intake valve 344 opens and closes.

  On the other hand, during high rotation, the intake high cam rocker arm 330 is driven by the intake high cam 237. Thereby, the intake low cam rocker arm 340 is driven by the intake high cam rocker arm 330. Therefore, the adjuster 342 of the intake low cam rocker arm 340 moves up and down by the rotation of the intake high cam 237, and the intake valve 344 performs an up and down operation (lift operation). As a result, the intake valve 344 opens and closes.

  Thus, the rotational force of the intake low cam 241 is transmitted to the intake valve 344 via the intake low cam rocker arm 340, and the rotational force of the intake high cam 237 is intake via the intake high cam rocker arm 330 and the intake low cam rocker arm 340. It is transmitted to the valve 344. The amount of displacement of the intake valve 344 during low rotation (hereinafter referred to as lift amount) depends on the length of the cam nose 241A of the intake low cam 241, and the amount of lift of the intake valve 344 during high rotation is the amount of the cam nose 237A of the intake high cam 237. Depends on length.

  Here, in order to bring both the adjuster 332 of the intake high cam rocker arm 330 and the adjuster 342 of the intake low cam rocker arm 340 into contact with the stem end 344a of the intake valve 344, it is necessary to increase the area of the upper surface of the stem end 344a. is there. In contrast, in the present embodiment, the vertical movement of the intake high cam rocker arm 330 is transmitted to the intake valve 344 via the intake low cam rocker arm 340, so that the area of the upper surface of the stem end 344a of the intake valve 344 is reduced. In addition, it is possible to prevent an uneven load from being applied to the intake valve 344.

  The exhaust cam rocker arm 350 includes a cam receiving portion 350T, an arm 350R, an adjuster 352, and a nut 353, similarly to the intake high cam rocker arm 330 and the intake low cam rocker arm 340.

  An exhaust valve 354 is positioned below the adjuster 352 of the exhaust cam rocker arm 350. The exhaust valve 354 is provided with a valve spring 357. The valve spring 357 biases the intake valve 344 upward. The exhaust cam rocker arm 350 is driven by the exhaust cam 242. Therefore, the adjuster 352 of the exhaust cam rocker arm 350 moves up and down by the rotation of the exhaust cam 242, and the exhaust valve 354 performs the up and down operation (lift operation). As a result, the exhaust valve 354 opens and closes.

(7) Valve Lift Amount FIG. 13 shows the lift amounts of the intake valve 344 and the exhaust valve 354 shown in FIG.

  In FIG. 13, the horizontal axis indicates the crank angle (the rotation angle of the crankshaft 23), and the vertical axis indicates the lift amount of the exhaust valve 354 and the intake valve 344 (the vertical displacement of the exhaust valve 354 and the intake valve 344). Show.

  In FIG. 13, the exhaust valve 354 and the intake valve 344 are open when the lift amount is greater than zero, and are closed when the lift amount is zero.

  The crank angle is shown from -360 ° to + 360 °. When the crank angle is 0 °, 360 °, and −360 °, the piston 21 (FIG. 2) is located at the top dead center TDC in the cylinder 20, and when the crank angle is 180 ° and −180 °, the piston 21 (FIG. 2) is located at the bottom dead center BDC in the cylinder 20.

  A valve lift curve 242L indicated by a solid line indicates a change in the lift amount of the exhaust valve 354 due to the rotation of the exhaust cam 242 (FIG. 9). According to the valve lift curve 242L, the maximum lift amount of the exhaust valve 354 is the maximum value L1.

  A valve lift curve 241L indicated by a one-dot chain line indicates a change in the lift amount of the intake valve 344 at the time of low rotation. According to the valve lift curve 241L, the maximum lift amount of the intake valve 344 is the maximum value L2. In this case, as described above, the lift amount of the intake valve 344 depends on the length of the cam nose 241A of the intake low cam 241.

  On the other hand, a valve lift curve 237L indicated by a dotted line indicates a change in the lift amount of the intake valve 344 at the time of high rotation. According to the valve lift curve 237L, the maximum lift amount of the intake valve 344 is a maximum value L1 that is greater than the maximum value L2 and equal to the maximum lift amount of the exhaust valve 354. In this case, as described above, the lift amount of the intake valve 344 depends on the length of the cam nose 237A of the intake high cam 237.

  As described above, the lift amount of the intake valve 344 at the time of high rotation is larger than the lift amount of the intake valve 344 at the time of low rotation. Thereby, at the time of high rotation, it is possible to secure a larger amount of intake air to the cylinder 20 of FIG. 2 than at the time of low rotation. As a result, it is possible to improve fuel efficiency during normal travel, reduce harmful substances in the exhaust gas, and achieve high output during high speed travel.

  In the present embodiment, the maximum lift amount of the exhaust valve 354 and the maximum lift amount of the intake valve 344 at the time of high rotation are set to be equal, but the maximum lift amount of the exhaust valve 354 and at the time of high rotation are set. The maximum lift amount of the intake valve 344 may be different.

(8) Effects of the present embodiment In the present embodiment, the variable valve apparatus 200 that switches between the intake high cam 237 and the intake low cam 241 using the centrifugal force due to rotation is used. In this case, compared with the case where the two intake cams are switched by hydraulic pressure, the hydraulic actuator and the hydraulic pump are not required, so that the intake high cam 237 and the intake low cam 241 can be switched at a smaller size and at a lower cost. As a result, fuel efficiency during normal driving can be improved, harmful substances in the exhaust gas can be reduced, and high output during high-speed driving can be realized.

  Further, in the present embodiment, the intake high cam 237 and the intake low cam 241 are switched by inserting and pulling out the lock pins 214 and 217 into the lock pin fitting holes 236b and 236c without using frictional force between the constituent members. Is called. Thereby, there is almost no deterioration due to wear of the component parts. As a result, it is possible to extend the life of the variable valve operating apparatus 200 without using wear-resistant components, and to reduce the cost.

  In addition, since the machining and insertion of the lock pins 214 and 217 to and from the lock pin fitting holes 236b and 236c can be realized with only a mechanical structure without requiring high processing accuracy, the manufacture is facilitated.

(9) Correspondence between Each Component of Claim and Each Part of Embodiment In the above embodiment, the intake valve 344 and the exhaust valve 354 correspond to valves, the cam fixing shaft 244 corresponds to a rotating shaft, and the intake low cam 241 corresponds to the first cam member, the floating cam portion 235 corresponds to the second cam member, the lock pins 214 and 217 correspond to the locking members, and the springs S1 and S2 correspond to the biasing member, Weights 213 and 216 correspond to drive members.

  Further, the tips of the lock pins 214 and 217 correspond to the locking portions, the lock pin fitting holes 236b and 236c correspond to the locked portions, the lock plate 233 corresponds to the movement preventing member, and the groove portions 214a, 214b, 217a and 217b correspond to groove portions, lock pin engaging portions 233b and 233c correspond to fitting portions, intake low cam rocker arm 340 corresponds to a first transmission member, and intake high cam rocker arm 330 performs a second transmission. It corresponds to a member.

  Further, the state of the lock pins 214 and 217 during low rotation shown in FIG. 7 corresponds to the first state, and the positions of the weights 213 and 216 during low rotation correspond to the first position, as shown in FIG. The state of the lock pins 214 and 217 at the time of high rotation corresponds to the second state, the positions of the weights 213 and 216 at the time of high rotation correspond to the second position, and the low rotation indicated by the one-dot chain line in FIG. The lift amount of the intake valve 344 at the time corresponds to the first lift amount, and the lift amount of the intake valve 344 at the time of high rotation shown by the dotted line corresponds to the second lift amount.

  The engine 7 and the variable valve apparatus 200 correspond to the engine device, the motorcycle 100 corresponds to the vehicle, the rear wheel 11 corresponds to the drive wheel, the rear wheel driven sprocket 12, the drive shaft 26, the rear wheel drive sprocket. 15 and the chain 16 correspond to a transmission mechanism.

(10) Other embodiments (10-1)
The variable valve operating apparatus 200 of the above embodiment is provided with two weights 213 and 216 and two lock pins 214 and 217. Only one of the weights 213 and 216 and the lock pins 214 and 217 is provided. Also good. An example of the variable valve operating apparatus 200 in that case is shown in FIG.

  The variable valve operating apparatus 200 shown in FIG. 14 does not have the weight 213 and the lock pin 214 in the variable valve operating apparatus 200 shown in FIGS.

  FIG. 14A is a cross-sectional view of the variable valve apparatus 200 during low rotation, and FIG. 14B is a cross-sectional view taken along the line P-P in FIG.

  As shown in FIG. 14 (a), the variable valve operating apparatus 200 includes a lock pin holding mechanism 210, a cam driven sprocket 220, a lock pin locking mechanism 230, an idle cam portion 235, and a cam shaft 240.

  The lock pin holding mechanism 210 is provided with a weight 216 and a lock pin 217. As shown in FIGS. 7 and 8, the weight 216 and the lock pin 217 are configured so that the floating cam portion 235 can be rotated with respect to the cam fixing shaft 244 and fixed according to the rotational speed of the engine 7. Switch.

  Further, the movement of the lock pin 217 is limited by the lock pin engaging portion 233 b of the lock plate 233.

  As shown in FIG. 14B, the lock plate 233 in this case has a long lock pin engaging portion 233b extending along one side of the substantially rectangular support plate 233a.

  When the variable valve apparatus 200 is provided with a set of weights 216 and a lock pin 217 as in this example, it is possible to improve fuel efficiency during normal travel and reduce harmful substances in the exhaust gas, High output during high speed driving can be realized. Moreover, further miniaturization of the variable valve apparatus 200 can be realized.

(10-2)
In the valve control device 200 of the above embodiment, the lift amount of the intake valve 344 is changed by switching the intake high cam 237 and the intake low cam 241, but the operating angle of the intake valve 344 may be changed. Here, the operating angle of the intake valve 344 refers to a crank angle range in a state where the intake valve 344 is lifted. For example, in FIG. 13, the operating angle of the intake valve 344 is 260 ° (from −30 ° to 230 °).

  In this case, by forming the width of the cam nose 237A of the intake high cam 237 larger than the width of the cam nose 241A of the intake low cam 241, the operating angle of the intake valve 344 at the time of high rotation becomes the operating angle of the intake valve 344 at the time of low rotation. Bigger than.

  When the length of the cam nose 237A of the intake high cam 237 and the length of the cam nose 241A of the intake low cam 241 are equal, the operating angle of the intake valve 344 can be switched, and the cam nose 237A of the intake high cam 237 can be switched as in the above embodiment. Is longer than the length of the cam nose 241A of the intake low cam 241, both the lift amount of the intake valve 344 and the operating angle of the intake valve 344 can be switched.

(10-3)
The variable valve device 200 according to the present invention may be applied to the exhaust valve 354.

  In this case, the floating cam portion, the lock pin locking mechanism, and the cam driven sprocket having the same structure as that of the floating cam portion 235, the lock pin locking mechanism 230, and the cam driven sprocket 220 are disposed adjacent to the exhaust valve 354. An exhaust high cam rocker arm having the same structure as the intake high cam rocker arm 330 is provided.

  Thereby, the lift amount of the exhaust valve 354 can be switched.

(10-4)
In the above embodiment, the lock pins 214 and 217 are provided with the two groove portions 214a and 217a and the groove portions 214b and 217b, respectively, but only one of them may be provided.

  For example, only the groove 214a may be provided on the lock pin 214, and only the groove 217a may be provided on the lock pin 217. In this case, during low rotation, the lock pin engaging portions 233b and 233c of the lock plate 233 are fitted into the grooves 214a and 217a of the lock pins 214 and 217, and movement of the lock pins 214 and 217 is restricted.

  Alternatively, only the groove 214b may be provided on the lock pin 214, and only the groove 217b may be provided on the lock pin 217. In this case, during high rotation, the lock pin engaging portions 233b and 233c of the lock plate 233 are fitted into the grooves 214b and 217b of the lock pins 214 and 217, and movement of the lock pins 214 and 217 is restricted.

(10-5)
In the above embodiment, the plate-like lock plate 233 is used as the movement prevention member for restricting the movement of the lock pins 214 and 217, but a movement prevention member having another shape such as a pin shape may be used. Good. In this case, the shapes of the grooves 214a, 214b, 217a, and 217b formed in the lock pins 214 and 217 are appropriately determined according to the shape of the movement preventing member.

(10-6)
In the above embodiment, the variable valve operating apparatus 200 is provided in the engine 7 having the SOHC (single overhead camshaft) structure, but the engine 7 provided with the variable valve operating apparatus 200 may be provided with a camshaft. It is not limited.

  For example, the engine 7 may be an SV (side valve) engine, an OHV (overhead valve) engine, or a DOHC (double overhead camshaft) engine.

(10-7)
As described with reference to FIGS. 10 to 12, the variable valve gear 200 is provided in the engine 7 including the intake high cam rocker arm 330, the intake low cam rocker arm 340, and the exhaust cam rocker arm 350. The variable valve device 200 may be provided in a direct hitting engine.

(10-8)
In the above embodiment, the variable valve apparatus 200 uses the springs S1 and S2 to urge the weights 213 and 216 in a predetermined direction. However, rubber or the like may be used instead of the springs S1 and S2 as long as it is an elastic body that biases the weights 213 and 216 in a predetermined direction.

(10-9)
In the above-described embodiment, a motorcycle has been described as a vehicle. However, the present invention is not limited to this, and the variable valve operating apparatus 200 can be provided in a small vehicle with a small displacement such as a tractor and a cart and an engine of a small ship.

  The present invention can be used for various vehicles and ships equipped with engines such as motorcycles and automobiles of four wheels.

1 is a schematic diagram of a motorcycle according to an embodiment of the present invention. It is a figure for demonstrating the outline | summary of the variable valve apparatus which concerns on one embodiment of this invention. It is an assembly perspective view for demonstrating the structure of a variable valve apparatus. It is an assembly perspective view for demonstrating the structure of a variable valve apparatus. It is an assembly perspective view for demonstrating the structure of a variable valve apparatus. It is a XZ plane sectional view of a lock board storing member in the state where a lock board and a spring were inserted. It is sectional drawing which shows the state of the variable valve apparatus at the time of low rotation. It is sectional drawing which shows the state of the variable valve apparatus at the time of high rotation. It is a figure for demonstrating the detail of operation | movement of the lock plate and lock pin of FIG. 7 and FIG. It is sectional drawing which shows the attachment state to the engine of a variable valve apparatus. FIG. 11 is a top view showing the arrangement of the variable valve operating device, intake high cam rocker arm, intake low cam rocker arm and exhaust rocker arm of FIG. 10. It is sectional drawing in the RR line of the cylinder head of FIG. It is a figure which shows the displacement amount of the intake valve and exhaust valve which are shown in FIG. It is a figure which shows the modification of a variable valve apparatus.

Explanation of symbols

7 Engine 11 Rear wheel 12 Rear wheel driven sprocket 15 Rear wheel drive sprocket 16 Chain 26 Drive shaft 100 Vehicle 200 Variable valve gear 210 Lock pin holding mechanism 213, 216 Weight 214, 217 Lock pin 214a, 217a Groove 220 Cam driven sprocket 230 Lock pin locking mechanism 230
233 Lock plate 233b, 233c Lock pin locking portion 235 Free cam portion 235
236b, 236c Lock pin fitting hole 235 idle cam portion 237 intake high cam 240 camshaft 240
241 Intake low cam 242 Exhaust cam 244 Cam fixed shaft 330 Intake high cam rocker arm 340 Intake low cam rocker arm 344 Intake valve 350 Exhaust cam rocker arm 354 Exhaust valve S1, S2 Spring 237L, 241L, 242L Valve lift curve

Claims (14)

A variable valve gear for driving a valve of an engine,
A rotating shaft provided rotatably in conjunction with the rotation of the engine;
A first cam member provided to rotate with the rotating shaft and acting to open and close the valve;
A second cam member provided rotatably with respect to the rotating shaft and acting to open and close the valve;
A lock provided so as to be able to shift between a first state in which the second cam member is rotatable with respect to the rotating shaft and a second state in which the second cam member is locked with the rotating shaft. A member,
An urging member that generates an urging force that shifts the locking member to the first state;
A drive member that operates to shift the locking member to the second state against the urging force by the urging member by centrifugal force accompanying rotation of the rotating shaft;
When the locking member is in the first state, the first cam member acts to open and close the valve, and when the locking member is in the second state, the second cam A variable valve operating device, wherein a member acts to open and close the valve. The drive member is provided so as to be rotatable from a first position to a second position by centrifugal force accompanying rotation of the rotation shaft,
The locking member is provided to be movable in one direction along the rotation axis as the driving member rotates from the first position to the second position.
The biasing member applies a biasing force to the driving member so that the driving member is directed to the first position;
The locking member is in the first state when the driving member is in the first position, and is in the second state when the driving member is in the second position. The variable valve operating apparatus according to claim 1. The locking member has a locking portion,
The second cam member has a locked portion locked by the locking portion of the locking member,
When the locking member is in the first state, the locking portion is disengaged from the locked portion, and when the locking member is in the second state, the locking portion is locked The variable valve operating device according to claim 1 or 2, wherein the portion is locked. The locking member includes a rod-shaped member, and the locking portion is an end of the rod-shaped member,
The variable valve operating apparatus according to claim 3, wherein the locked portion of the second cam member is a hole portion into which an end portion of the rod-like member can be fitted. The locking member is a plurality of rod-shaped members, and the locked portion of the second cam member is a plurality of holes into which end portions of the plurality of rod-shaped members can be respectively fitted, and the plurality of rod-shaped members 5. The variable valve operating apparatus according to claim 4, wherein the members are disposed at positions that are asymmetric with respect to the center of the rotating shaft. The movement preventing member for preventing the movement of the locking member when the locking member is in at least one of the first state and the second state. The variable valve operating apparatus according to any one of the above. The locking member has at least one groove;
The said movement prevention member has a fitting part which can be fitted to the said groove part when the said locking member exists in at least one of the said 1st state and the said 2nd state. Variable valve gear. At least one of the case where the locking member transitions from the first state to the second state and the case where the locking member transitions from the second state to the first state. 8. The variable valve operating apparatus according to claim 7, wherein the groove portion and the fitting portion are formed so that the fitting portion of the movement preventing member can be retracted from the at least one groove portion. A first transmission member that moves the valve up and down by swinging in conjunction with rotation of the first cam member;
The variable movement according to claim 1, further comprising: a second transmission member that swings the first transmission member in conjunction with rotation of the second cam member. Valve device. The first cam member acts to open the valve with a first lift in the first state;
The said 2nd cam member acts so that the said valve may be opened by the 2nd lift amount larger than the said 1st lift amount in the said 2nd state. The variable valve operating device described. The first cam member acts to open the valve at a first operating angle in the first state;
The said 2nd cam member acts so that the said valve may be opened by the 2nd working angle larger than the said 1st working angle in the said 2nd state. The variable valve operating device described. The variable valve operating apparatus according to claim 1, wherein the valve is an intake valve. An engine having a valve;
A variable valve gear for driving the valve of the engine,
The variable valve operating device is:
A rotating shaft provided rotatably in conjunction with the rotation of the engine;
A first cam member provided to rotate with the rotating shaft and acting to open and close the valve;
A second cam member provided rotatably with respect to the rotating shaft and acting to open and close the valve;
A lock provided so as to be able to shift between a first state in which the second cam member is rotatable with respect to the rotating shaft and a second state in which the second cam member is locked with the rotating shaft. A member,
An urging member that generates an urging force that shifts the locking member to the first state;
A drive member that operates to shift the locking member to the second state against the urging force by the urging member by centrifugal force accompanying rotation of the rotating shaft;
When the locking member is in the first state, the first cam member acts to open and close the valve, and when the locking member is in the second state, the second cam An engine device characterized in that a member acts to open and close the valve. An engine device according to claim 13;
Driving wheels,
A vehicle comprising: a transmission mechanism that transmits power generated by the engine device to the drive wheels.

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