EP3309376A1 - Engine system and vehicle - Google Patents
Engine system and vehicle Download PDFInfo
- Publication number
- EP3309376A1 EP3309376A1 EP16811168.0A EP16811168A EP3309376A1 EP 3309376 A1 EP3309376 A1 EP 3309376A1 EP 16811168 A EP16811168 A EP 16811168A EP 3309376 A1 EP3309376 A1 EP 3309376A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- intake cam
- intake
- rotation
- sub
- cam
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
- F01L13/02—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for reversing
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/02—Valve drive
- F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/02—Valve drive
- F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
- F01L1/08—Shape of cams
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/12—Transmitting gear between valve drive and valve
- F01L1/18—Rocking arms or levers
- F01L1/181—Centre pivot rocking arms
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D13/00—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing
- F02D13/02—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing during engine operation
- F02D13/0223—Variable control of the intake valves only
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02N—STARTING OF COMBUSTION ENGINES; STARTING AIDS FOR SUCH ENGINES, NOT OTHERWISE PROVIDED FOR
- F02N19/00—Starting aids for combustion engines, not otherwise provided for
- F02N19/005—Aiding engine start by starting from a predetermined position, e.g. pre-positioning or reverse rotation
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/46—Component parts, details, or accessories, not provided for in preceding subgroups
- F01L2001/467—Lost motion springs
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L2305/00—Valve arrangements comprising rollers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L2760/00—Control of valve gear to facilitate reversing, starting, braking of four stroke engines
- F01L2760/002—Control of valve gear to facilitate reversing, starting, braking of four stroke engines for reversing or starting four stroke engines
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L2820/00—Details on specific features characterising valve gear arrangements
- F01L2820/03—Auxiliary actuators
- F01L2820/032—Electric motors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2250/00—Engine control related to specific problems or objectives
- F02D2250/06—Reverse rotation of engine
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02N—STARTING OF COMBUSTION ENGINES; STARTING AIDS FOR SUCH ENGINES, NOT OTHERWISE PROVIDED FOR
- F02N19/00—Starting aids for combustion engines, not otherwise provided for
- F02N19/005—Aiding engine start by starting from a predetermined position, e.g. pre-positioning or reverse rotation
- F02N2019/007—Aiding engine start by starting from a predetermined position, e.g. pre-positioning or reverse rotation using inertial reverse rotation
Definitions
- the present invention relates to an engine system and a vehicle including the engine system.
- a movement direction of a piston during the reverse rotation of the crankshaft is opposite to a movement direction of the piston during the forward rotation of the crankshaft. Therefore, in order to introduce a fuel-air mixture into the combustion chamber during the reverse rotation of the crankshaft, it is necessary that an intake valve is lifted in a range of a crank angle different from that of a normal intake stroke.
- a sub-intake cam for lifting the intake valve during the reverse rotation of the crankshaft is provided in addition to a main intake cam for lifting the intake valve during the forward rotation of the crankshaft.
- a sub-intake cam is provided to be rotatable in a constant angular range with respect to a shaft portion of a camshaft.
- a cam nose of the sub-intake cam does not overlap with a cam nose of the main intake cam, so that the sub-intake cam lifts the intake valve separately from the main intake cam.
- the cam nose of the sub-intake cam overlaps with the cam nose of the main intake cam, so that the sub-intake cam does not act on the intake valve.
- the sub-intake cam is biased by a torsion coil spring towards a first position.
- An object of the present invention is to provide an engine system and a vehicle in which startability of an engine can be enhanced while the generation of an abnormal noise is prevented.
- the above-mentioned engine system is used, so that startability of the engine can be enhanced while the generation of an abnormal noise is prevented.
- the present invention enables startability of the engine to be enhanced while preventing the generation of an abnormal noise.
- the motorcycle is one example of a vehicle.
- Fig. 1 is a schematic side view showing a schematic configuration of the motorcycle according to one embodiment of the present invention.
- a front fork 2 is provided at a front portion of a vehicle body 1 to be swingable to the right and the left.
- a handle 4 is attached to an upper end of the front fork 2, and a front wheel 3 is rotatably attached to a lower end of the front fork 2.
- a seat 5 is provided at a substantially central upper portion of the vehicle body 1.
- An ECU (Engine Control Unit) 6, a battery BT and an engine unit EU are provided below the seat 5.
- the ECU 6, the battery BT and the engine unit EU constitute an engine system 200.
- a rear wheel 7 is rotatably attached to a lower portion of a rear end of the vehicle body 1. The rotation of the rear wheel 7 is driven by the motive power generated by the engine unit EU.
- Fig. 2 is a schematic diagram for explaining a configuration of the engine system 200.
- the engine unit EU includes an engine 10 and a rotary electrical machine 14.
- the engine 10 includes a cylinder CY, a piston 11, a connecting rod 12, a crankshaft 13, an intake valve 15, an exhaust valve 16, a valve driver 17, an injector 18 and an ignition device 19.
- the piston 11 is provided to be reciprocatable in the cylinder CY and connected to the crankshaft 13 via the connecting rod 12.
- the crankshaft 13 is provided with the rotary electrical machine 14.
- the rotary electrical machine 14, which is connected to the battery BT, can drive the crankshaft 13 in a forward direction or a reverse direction by electrical power supplied from the battery BT, and can charge the battery BT by electrical power generated by the rotation of the crankshaft 13.
- the forward direction is a direction in which the crankshaft 13 rotates during a normal operation of the engine 10, whereas the reverse direction is a direction opposite to the forward direction.
- the rotary electrical machine 14 transmits a torque directly to the crankshaft 13 without a reduction gear.
- the rotation of the crankshaft 13 in the forward direction (forward rotation) is transmitted to the rear wheel 7, so that the rotation of the rear wheel 7 is driven.
- a starter motor and a generator may be provided separately instead of the rotary electrical machine 14.
- a combustion chamber 31a is divided into sections by the cylinder CY and the piston 11.
- the combustion chamber 31a communicates with an intake passage 22 through an intake port 21 and communicates with an exhaust passage 24 through an exhaust port 23.
- An intake valve 15 is provided to open and close the intake port 21, and an exhaust valve 16 is provided to open and close the exhaust port 23.
- the intake valve 15 and the exhaust valve 16 are driven by the valve driver 17. Details of the valve driver 17 will be described below.
- a throttle valve TV for adjusting a flow rate of air flowing in from the outside is provided in the intake passage 22.
- the injector 18 is configured to inject fuel into the intake passage 22.
- the ignition device 19 is configured to ignite a fuel-air mixture in the combustion chamber 31a.
- the fuel injected by the injector 18 is mixed with air and then guided to the combustion chamber 31a, and the fuel-air mixture in the combustion chamber 31a is ignited by the ignition device 19.
- the reciprocating motion of the piston 11 due to the combustion of the fuel-air mixture is converted into the rotation motion of the crankshaft 13.
- the rotation force of the crankshaft 13 is transmitted to the rear wheel 7 of Fig. 1 , so that the rear wheel 7 is driven.
- the ECU 6 includes a CPU (Central Processing Unit) and a memory, for example. A microcomputer may be used instead of the CPU and the memory.
- the ECU 6 is electrically connected with a main switch 40, a starter switch 41, an intake pressure sensor 42, a crank angle sensor 43 and a current sensor 44.
- the main switch 40 is provided below the handle 4 of Fig. 1 , for example, and the starter switch 41 is provided on the handle 4 of Fig. 1 , for example.
- the main switch 40 and the starter switch 41 are operated by a rider.
- the intake pressure sensor 42 detects a pressure in the intake passage 22.
- the crank angle sensor 43 detects a crank angle indicating a rotation position of the crankshaft 13.
- the current sensor 44 detects a current flowing in the rotary electrical machine 14.
- the operations or actuations of the main switch 40 and the starter switch 41 are supplied as operation signals to the ECU 6, and the results of detection by the intake pressure sensor 42, the crank angle sensor 43 and the current sensor 44 are supplied as detection signals to the ECU 6.
- the ECU 6 controls the rotary electrical machine 14, the injector 18 and the ignition device 19 based on the supplied operation signal and the supplied detection signal.
- the engine 10 is started when the main switch 40 of Fig. 2 is turned on and the starter switch 41 is turned on, whereas the engine 10 is stopped when the main switch 40 of Fig. 2 is turned off.
- Start-up of the engine 10 refers to a combustion in the combustion chamber 31a being started by a start of fuel injection by the injector 18 and a start of ignition by the ignition device 19.
- Stopping of the engine 10 refers to the combustion in the combustion chamber 31a being stopped by the stoppage of at least one of the fuel injection by the injector 18 and the ignition by the ignition device 19.
- the idle stop condition may include a condition that relates to at least one of, for example, a throttle opening (a degree of opening of a throttle valve TV), a vehicle speed and a rotation speed of the engine 10 (a rotation speed of the crankshaft 13), and may further include another condition such as a condition that a brake lever is operated.
- the re-start condition refers to, for example, the throttle opening being larger than 0 when an accelerator grip is operated, and may include another condition such as a condition that an operation of the brake lever is released.
- the engine unit EU performs a reverse rotation start-up operation during the start-up of the engine 10. Thereafter, the engine unit EU performs a normal operation that includes an intake stroke, a compression stroke, an expansion stroke and an exhaust stroke.
- Fig. 3 is a diagram for explaining the normal operation of the engine unit EU.
- Fig. 4 is a diagram for explaining the reverse rotation start-up operation of the engine unit EU.
- a top dead center through which the piston 11 passes at the time of shifting from the compression stroke to the expansion stroke is referred to as a compression top dead center
- a top dead center through which the piston 11 passes at the time of shifting from the exhaust stroke to the intake stroke is referred to as an exhaust top dead center
- a bottom dead center through which the piston 11 passes at the time of shifting from the intake stroke to the compression stroke is referred to as an intake bottom dead center
- a bottom dead center through which the piston 11 passes at the time of shifting from the expansion stroke to the exhaust stroke is referred to as an expansion bottom dead center.
- the range of the crank angle which is equivalent to two rotations (720 degrees) of the crankshaft 13 is represented by one circle.
- the two rotations of the crankshaft 13 are equivalent to one cycle of the engine 10.
- the crank angle sensor 43 of Fig. 2 detects a rotation position in a range in which the crankshaft 13 rotates once (360 degrees). Based on the pressure in the intake passage 22 detected by the intake pressure sensor 42, the ECU 6 determines to which one of the two rotations of the crankshaft 13 equivalent to one cycle of the engine 10 the angle detected by the crank angle sensor 43 corresponds. Thus, the ECU 6 can acquire the rotation position in the range of two rotations (720 degrees) of the crankshaft 13 as the crank angle.
- an angle A0 is a crank angle when the piston 11 ( Fig. 2 ) is positioned at the exhaust top dead center
- an angle A2 is a crank angle when the piston 11 is positioned at the compression top dead center
- an angle A1 is a crank angle when the piston 11 is positioned at the intake bottom dead center
- an angle A3 is a crank angle when the piston 11 is positioned at the expansion bottom dead center.
- An arrow R1 indicates a direction in which the crank angle changes during the forward rotation of the crankshaft 13
- an arrow R2 indicates a direction in which the crank angle changes during the reverse rotation of the crankshaft 13.
- Arrows P1 to P4 indicate directions in which the piston 11 moves during the forward rotation of the crankshaft 13.
- Arrows P5 to P8 indicate directions in which the piston 11 moves during the reverse rotation of the crankshaft 13.
- crankshaft 13 ( Fig. 2 ) rotates forwardly, so that the crank angle changes in the direction of the arrow R1.
- the piston 11 ( Fig. 2 ) is lowered in a range from the angle A0 to the angle A1, raised in a range from the angle A1 to the angle A2, lowered in a range from the angle A2 to the angle A3, and raised in a range from the angle A3 to the angle A0.
- the fuel is injected into the intake passage 22 ( Fig. 2 ) by the injector 18 ( Fig. 2 ).
- the angle A11 is positioned at a further advanced angle than the angle A0.
- the intake port 21 ( Fig. 2 ) is subsequently opened by the intake valve 15 ( Fig. 2 ) in a range from an angle A12 to an angle A13.
- a fuel-air mixture including air and fuel is introduced into the combustion chamber 31a ( Fig. 2 ) through the intake port 21.
- the angle A12 is positioned at a further retarded angle than the angle A11 and at a further advanced angle than the angle A0
- the angle A13 is positioned at a further retarded angle than the angle A1.
- the fuel-air mixture in the combustion chamber 31a ( Fig. 2 ) is ignited by the ignition device 19 ( Fig. 2 ).
- the angle A14 is positioned at a further retarded angle than the angle A13 and at a further advanced angle than the angle A2.
- the fuel-air mixture is ignited, so that the fuel-air mixture is combusted in the combustion chamber 31a.
- the exhaust port 23 ( Fig. 2 ) is opened by the exhaust valve 16 ( Fig. 2 ) in a range from an angle A15 to an angle A16.
- the combusted gas is discharged from the combustion chamber 31a through the exhaust port 23.
- the angle A15 is positioned at a further advanced angle than the angle A3, and the angle A16 is positioned at a further retarded angle than the angle A0.
- crank angle is adjusted to an angle A20 by the forward rotation of the crankshaft 13 before the reverse rotation start-up operation.
- the angle A20 is positioned at a further retarded angle than the angle A1 and at a further advanced angle than the angle A2.
- the crank angle changes in a direction of the arrow R2 by the reverse rotation of the crankshaft 13 by the rotary electrical machine 14 ( Fig. 2 ).
- the piston 11 is lowered in a range from the angle A2 to the angle A1, raised in a range from the angle A1 to the angle A0, lowered in the range from the angle A0 to the angle A3, and raised in a range from the angle A3 to the angle A2.
- the direction in which the piston 11 moves during the reverse rotation of the crankshaft 13 is opposite to the direction in which the piston 11 moves during the forward rotation of the crankshaft 13.
- the intake port 21 is opened in a range from the angle A13 to the angle A12
- the exhaust port 23 is opened in a range from the angle A16 to the A15 similarly to during the forward rotation.
- the angle A23 is positioned at a further retarded angle than the angle A1 and at a further advanced angle than the angle A0.
- the intake port 21 ( Fig. 2 ) is opened by the intake valve 15 ( Fig. 2 ) in a range from an angle A21 to an angle A22.
- the angles A21, A21 are positioned in the range, from the angle A0 to the angle A3, corresponding to the exhaust stroke during the normal operation. In the range from the angle A1 to the angle A0, the piston 11 is raised.
- the fuel-air mixture introduced into the combustion chamber 31a is compressed.
- the fuel-air mixture in the combustion chamber 31a is ignited by the ignition device 19 ( Fig. 2 ), and a direction in which the crankshaft 13 is driven by the rotary electrical machine 14 is switched from the reverse direction to the forward direction.
- the angle A31 is positioned at a further retarded angle than the angle A3 and at a further advanced angle than the angle A2. For example, when a current of the rotary electrical machine 14 detected by the current sensor 44 of Fig. 2 reaches a threshold value, the fuel-air mixture is ignited by the ignition device 19.
- crankshaft 13 is driven in the forward direction by the combustion of the fuel-air mixture, so that a forward torque of the crankshaft 13 is increased.
- the crank angle can exceed the angle A2 corresponding to the first compression top dead center.
- the crankshaft 13 does not have to be driven in the forward direction by the rotary electrical machine 14. Thereafter, the engine unit EU is shifted to the above-mentioned normal operation.
- FIG. 5 is an exploded perspective view of the valve driver 17
- Fig. 6 is a cross-sectional view of the valve driver 17 and its peripheral portions.
- the valve driver 17 includes a camshaft 170, a one-way clutch 175, a sub-intake cam 177, a friction member FR1, a holder 179, a friction member FR2, an intake rocker arm RA1 and an exhaust rocker arm RA2.
- the camshaft 170 includes a shaft portion 171, an exhaust cam 172, an intake cam 173 and a shaft portion 174.
- the shaft portions 171, 174 are provided to extend in one direction with the exhaust cam 172 and the intake cam 173 sandwiched therebetween.
- An axial center of the shaft portion 171 and an axial center of the shaft portion 174 are positioned on a common straight line.
- an axis direction refers to a direction in parallel with the axial centers of the shaft portions 171, 174
- a circumferential direction refers to a direction that extends along a circle formed about the axial centers of the shaft portions 171, 174.
- the exhaust cam 172 and the intake cam 173 respectively have predetermined cam profiles and are provided between the shaft portions 171, 174 to be arranged in the axis direction.
- a cutout 173a is formed in a peripheral edge of one surface of the intake cam 173.
- the one-way clutch 175 is of cylindrical shape.
- the one-way clutch 175 is rotatable in one direction of the circumferential direction with respect to the shaft portion 174, and is non-rotatable in the opposite direction. A rotation direction of the one-way clutch 175 will be described below.
- the sub-intake cam 177, the friction member FR1, the holder 179 and the friction member FR1 are respectively provided to be annular.
- the sub-intake cam 177 has a predetermined cam profile.
- a projection piece 177a is provided at one surface of the sub-intake cam 177.
- a rotatable angular range of the sub-intake cam 177 with respect to the shaft portion 174 is restricted by the projection piece 177a and the cutout 173a of the intake cam 173.
- the range of the rotation of the sub-intake cam 177 will be described below.
- a cylindrical storage 177b is provided on the other surface of the sub-intake cam 177.
- the friction member FR1 is stored in the storage 177b.
- the holder 179 holds the friction member FR2.
- the friction members FR1, FR2 are respectively elastic. For example, an oil seal made of synthetic rubber or the like is used as the friction member FR1, FR2.
- the intake rocker arm RA1 is provided to extend in a direction substantially orthogonal to the axis direction and on one side of the camshaft 170.
- the exhaust rocker arm RA2 is provided to extend in a direction substantially orthogonal to the axis direction and on the other side of the camshaft 170.
- the intake rocker arm RA1 and the exhaust rocker arm RA2 are provided to be respectively swingable with arm shafts SH1, SH2 (see Fig. 7 , described below) in parallel with the axis direction as centers.
- a roller RL1 is attached to one end of the intake rocker arm RA1, and a roller RL2 is attached to one end of the exhaust rocker arm RA2.
- the camshaft 170 is held by the bearings B1, B2 to be rotatable about an axial center AC of the shaft portions 171, 174 in the cylinder head CH of the engine 10.
- An inner peripheral surface of the bearing B1 abuts against an outer peripheral surface of the shaft portion 171, and an inner peripheral surface of the bearing B2 abuts against an outer peripheral surface of the shaft portion 174.
- the roller RL1 of the intake rocker arm RA1 abuts against the intake cam 173, and the roller RL2 of the exhaust rocker arm RA2 abuts against the exhaust cam 172.
- a slipper surface SS is provided in a portion of the intake rocker arm RA1 adjacent to the roller RL1 in the axis direction. The slipper surface SS abuts against the sub-intake cam 177.
- the one-way clutch 175 is attached onto the outer peripheral surface of the shaft portion 174.
- the sub-intake cam 177 is attached onto an outer peripheral surface of the one-way clutch 175 to be adjacent to the intake cam 173.
- the holder 179 is fixed to the cylinder head CH to be adjacent to the sub-intake cam 177 and partially surround the outer peripheral surface of the one-way clutch 175.
- An outer periphery of the friction member FR1 is fixed to the storage 177b of the sub-intake cam 177, and an inner periphery of the friction member FR1 is pressed against the outer peripheral surface of the one-way clutch 175.
- a rotational resistance is generated between the sub-intake cam 177 and the one-way clutch 175 by the friction member FR1.
- the inner periphery of the friction member FR1 may be fixed to the outer peripheral surface of the one-way clutch 175, and the outer periphery of the friction member FR1 may be pressed against an inner peripheral surface of the storage 177b of the sub-intake cam 177.
- a similar rotational resistance can be generated also in this case.
- the holder 179 is fixed to the cylinder head CH, thereby not moving in conjunction with the rotation of the camshaft 170.
- a part of the engine unit EU that does not move in conjunction with the rotation of the camshaft 170 is referred to as a stationary system.
- An outer periphery of the friction member FR2 is fixed to the holder 179, and an inner periphery of the friction member FR2 is pressed against the outer periphery of the one-way clutch 175. Therefore, the rotational resistance is generated between the stationary system and the one-way clutch 175 by the friction member FR2.
- the inner periphery of the friction member FR2 may be fixed to the outer peripheral surface of the one-way clutch 175, and the outer periphery of the friction member FR2 may be pressed against the inner peripheral surface of the holder 179.
- a similar rotational resistance can be generated also in this case.
- the rotational resistance generated by the friction member FR2 is smaller than the rotational resistance generated by the friction member FR1.
- Fig. 7 is a diagram for explaining a relationship among the valve driver 17, the intake valve 15 and the exhaust valve 16.
- the intake rocker arm RA1 is provided to be swingable with the arm shaft SH1 as a center
- the exhaust rocker arm RA2 is provided to be swingable with the arm shaft SH2 as a center.
- An abutment member AD1 is attached to an end opposite to the roller RL1 of the intake rocker arm RA1.
- the abutment member AD1 abuts against an upper end of the intake valve 15.
- An abutment member AD2 is attached to an end opposite to the roller RL2 of the exhaust rocker arm RA2.
- the abutment member AD2 abuts against an upper end of the exhaust valve 16.
- the intake valve 15 is biased in a direction of closing the intake port 21 ( Fig. 2 ) by a valve spring 15a.
- a valve spring 15a By a biasing force of the valve spring 15a, the intake valve 15 is pressed against the abutment member AD1, and the roller RL1 of the intake rocker arm RA1 is pressed against the intake cam 173. Further, the slipper surface SS of the intake rocker arm RA1 is pressed against the sub-intake cam 177 (see Fig. 6 ).
- the exhaust valve 16 is biased in a direction of closing the exhaust port 23 ( Fig. 2 ) by the valve spring 16a. By a biasing force of the valve spring 16a, the exhaust valve 16 is pressed against the abutment member AD2, and the roller RL2 of the exhaust rocker arm RA2 is pressed against the exhaust cam 172.
- a rotation direction of the camshaft 170 during the forward rotation of the crankshaft 13 is referred to as the forward direction (a direction Q1 of Fig. 7 )
- a rotation direction of the camshaft 170 during the reverse rotation of the crankshaft 13 is referred to as the reverse direction (a direction Q2 of Fig. 7 ).
- the camshaft 170 rotates forwardly or in reverse, whereby the intake cam 173 and the sub-intake cam 177 swing the intake rocker arm RA1, and the exhaust cam 172 swings the exhaust rocker arm RA2.
- the intake valve 15 opens and closes the intake port 21, and the exhaust valve 16 opens and closes the exhaust port 23.
- the one-way clutch 175 of Figs. 5 and 6 is rotatable in the forward direction Q1 and non-rotatable in the reverse direction Q2 with respect to the shaft portion 174. Specifically, the rotational resistance exerted on the one-way clutch 175 from the shaft portion 174 in the reverse direction Q2 is significantly small, and the rotational resistance exerted on the one-way clutch 175 from the shaft portion 174 in the forward direction Q1 is significantly large. The rotational resistance exerted on the one-way clutch 175 from the shaft portion 174 in the reverse direction Q2 is reduced by a rolling bearing, for example.
- Fig. 8 is a diagram for explaining a rotatable angular range of the sub-intake cam 177.
- the one-way clutch 175 is not shown.
- a cutout 173a of the intake cam 173 is provided to extend in a circumferential direction.
- the projection piece 177a of the sub-intake cam 177 is provided to extend in the circumferential direction.
- a length of the cutout 173a in the circumferential direction is larger than a length of the projection piece 177a in the circumferential direction.
- the projection piece 177a is arranged in the cutout 173a.
- one end TA1 of the projection piece 177a abuts against one end TB1 of the cutout 173a, whereby the rotation of the sub-intake cam 177 in the reverse direction Q2 with respect to the shaft portion 174 is prevented.
- the other end TA2 of the projection piece 177a abuts against the other end TB2 of the cutout 173a, whereby the rotation of the sub-intake cam 177 in the forward direction Q1 with respect to the shaft portion 174 is prevented.
- a rotatable angular range of the sub-intake cam 177 with respect to the shaft portion 174 is restricted.
- a difference of an angle between the one end TB1 and the other end TB2 of the cutout 173a in the circumferential direction from an angle between the one end TA1 and the other end TA2 of the projection piece 177a in the circumferential direction is an angle by which the sub-intake cam 177 can rotate with respect to the shaft portion 174.
- the cam nose 177T of the sub-intake cam 177 deviates from the cam nose 173T of the intake cam 173 by a constant angle in the circumferential direction, and at least a part of the cam nose 177T of the sub-intake cam 177 does not overlap with the cam nose 173T of the intake cam 173.
- a start-up position such a relative position of the sub-intake cam 177 with respect to the intake cam 173 is referred to as a start-up position.
- the sub-intake cam 177 does not act on the intake rocker arm RA1 ( Fig. 7 ) at the normal position. On the other hand, the sub-intake cam 177 acts on the intake rocker arm RA1 at the start-up position. In this case, when the crank angle is in a range from the angle A21 to the angle A22 of Fig. 4 , the intake rocker arm RA1 is driven and the intake valve 15 ( Fig. 7 ) is lifted.
- Figs. 9 and 10 are diagrams for explaining the operations of the intake cam 173 and the sub-intake cam 177 in the reverse rotation start-up operation.
- the sub-intake cam 177 is at the normal position as shown in Fig. 9(a) .
- the camshaft 170 rotates in the reverse direction Q2 as shown in Fig. 9(b) .
- the rotational resistance hereinafter referred to as the stationary system rotational resistance
- the stationary system rotational resistance generated by the friction member FR2 of Fig. 6 is exerted between the stationary system and the one-way clutch 175.
- the one-way clutch 175 is rotatable in the forward direction Q1 with respect to the shaft portion 174, so that the one-way clutch 175 rotates in the forward direction Q1 with respect to the shaft portion 174 by the stationary system rotational resistance.
- the rotational resistance (hereinafter referred to as the sub-cam rotational resistance) generated by the friction member FR1 of Fig. 6 is exerted between the sub-intake cam 177 and the one-way clutch 175. Therefore, the sub-intake cam 177 does not rotate with respect to the one-way clutch 175, and rotates in the forward direction Q1 together with the one-way clutch 175 with respect to the shaft portion 174.
- the sub-intake cam 177 rotates with a delay relative to the intake cam 173 and moves from the normal position to the start-up position.
- the intake cam 173 pushes up the one end of the intake rocker arm RA1 as shown in Fig. 9(c) .
- the intake valve 15 of Fig. 7 is lifted.
- the sub-intake cam 177 reaches the start-up position, the rotation of the sub-intake cam 177 with respect to the shaft portion 174 in the forward direction Q1 is prevented. Therefore, the sub-intake cam 177 rotates in the reverse direction Q2 together with the shaft portion 174.
- the sub-cam rotational resistance is larger than the stationary system rotational resistance, so that the one-way clutch 175 rotates in the reverse direction Q2 together with the sub-intake cam 177 by the sub-cam rotational resistance.
- the cam nose 177T abuts against the intake rocker arm RA1 with the sub-intake cam 177 at the start-up position in the present example
- the cam nose 177T ( Fig. 8 ) may abut against the intake rocker arm RA1 with the sub-intake cam 177 not reaching the start-up position.
- the sub-intake cam 177 is rotated in the forward direction Q1 with respect to the shaft portion 174 by a counterforce of the intake rocker arm RA1.
- the sub-intake cam 177 reaches the start-up position.
- the sub-intake cam 177 does not push up the one end of the intake rocker arm RA1 until reaching the start-up position.
- the force in the reverse direction Q2 is applied from the intake rocker arm RA1 to the sub-intake cam 177.
- the tip end of the cam nose 177T refers to a portion in an outer peripheral surface of the cam nose 177T at which a distance from the axial center of the shaft portion 174 is maximum. Because the one-way clutch 175 is non-rotatable in the reverse direction Q2 with respect to the shaft portion 174, the one-way clutch 175 is not rotating in reverse with respect to the shaft portion 174.
- the force applied from the intake rocker arm RA1 to the sub-intake cam 177 is larger than the sub-cam rotational resistance, so that the sub-intake cam 177 rotates in the reverse direction Q2 with respect to the one-way clutch 175 while receiving the sub-cam rotational resistance as shown in Fig. 9(f) .
- a speed of the reverse rotation of the sub-intake cam 177 with respect to the shaft portion 174 decreases due to the sub-cam rotational resistance exerted between the sub-intake cam 177 and the one-way clutch 175. Therefore, the sub-intake cam 177 is prevented from instantaneously moving from the start-up position to the normal position. If the sub-intake cam 177 instantaneously moves from the start-up position to the normal position, the intake port 21 is instantaneously closed by the intake valve 15. Thus, the intake valve 15 collides with an edge of the intake port 21, and a contact noise is generated.
- a contact noise caused by the movement of the intake rocker arm RA1 may be generated in the valve driver 17.
- the sub-intake cam 177 gently moves from the start-up position to the normal position, so that the generation of such a contact noise is prevented.
- a fuel-air mixture is ignited in the combustion chamber 31a of Fig. 2 , and the crankshaft 13 is driven in the forward direction.
- the camshaft 170 rotates in the forward direction Q1.
- the one-way clutch 175 is non-rotatable in the reverse direction Q2 with respect to the shaft portion 174, thereby rotating together with the camshaft 170 in the forward direction Q1.
- the sub-intake cam 177 rotates in the forward direction Q1 together with the one-way clutch 175 by the sub-cam rotational resistance.
- the sub-intake cam 177 does not push up the one end of the intake rocker arm RA1, and is rotated in the reverse direction Q2 with respect to the one-way clutch 175 by a counterforce of the intake rocker arm RA1.
- the sub-intake cam 177 moves to the normal position. Thereafter, during a period in which the crank angle is in a range from the angle A12 to the angle A13 of Fig. 3 , the intake cam 173 pushes up the one end of the intake rocker arm RA1, so that the intake valve 15 of Fig. 7 is lifted. Thereafter, with the sub-intake cam 177 held at the normal position, the forward rotation of the camshaft 170 continues. Thus, during the normal operation, the sub-intake cam 177 does not drive the intake rocker arm RA1, and only the intake cam 173 drives the intake rocker arm RA1.
- the stationary system rotational resistance is exerted between the stationary system and the one-way clutch 175, and the sub-cam rotational resistance is exerted between the one-way clutch 175 and the sub-intake cam 177.
- the sub-intake cam 177 and the one-way clutch 175 are prevented from rotating in the forward direction Q1 with respect to the camshaft 170. Therefore, during the normal operation, the generation of an abnormal noise caused by the movement of the sub-intake cam 177 is prevented.
- the crankshaft 13 rotates in reverse and then a fuel-air mixture is combusted, so that the crankshaft 13 is driven in the forward direction.
- the startability of the engine 10 is enhanced.
- the sub-intake cam 177 rotates with a delay relative to the intake cam 173.
- the sub-intake cam 177 is not biased by a biasing member at the start-up position, the sub-intake cam 177 can be held at the normal position during the forward rotation of the crankshaft 13.
- the rotational resistance generated by the friction member FR2 is exerted between the stationary system and the one-way clutch 175, so that the sub-intake cam 177 rotates with a delay relative to the intake cam 173.
- the sub-intake cam 177 can be stably moved to the start-up position using a simple configuration.
- Fig. 11 is a diagram for explaining the first modified example of the valve driver 17. As for the example of Fig. 11 , differences from Figs. 5 and 6 will be described.
- the valve driver 17 of Fig. 11 includes a friction spring 180 instead of the holder 179 and the friction member FR2 of Figs. 5 and 6 .
- the friction spring 180 is a torsion spring and includes a coil 181 and arm portions 182, 183. In the present example, the coil 181 of the friction spring 180 is fitted with the arm shaft SH2.
- the arm portion 182 abuts against an outer peripheral surface of the storage 177b of the sub-intake cam 177.
- the arm portion 183 is fixed to the cylinder head CH ( Fig. 6 ). In this case, the arm portion 183 is pressed against the sub-intake cam 177 with a constant force. Thus, the rotational resistance is generated between the stationary system and the sub-intake cam 177.
- the sub-intake cam 177 rotates with a delay relative to the intake cam 173 during the reverse rotation of the crankshaft 13.
- the sub-intake cam 177 can be stably moved to the start-up position using a simple configuration.
- Fig. 12 is a diagram for explaining the second modified example of a valve driver 17. As for the example of Fig. 12 , differences from Figs. 5 and 6 will be described.
- the valve driver 17 of Fig. 12 includes a bar-shaped pressing member 185, a compression spring 186 and a support member 187 instead of the holder 179 and the friction member FR2 of Figs. 5 and 6 .
- One end of the pressing member 85 is attached to a fixing portion HP via a shaft member 185a.
- the fixing portion HP is provided at the cylinder head CH ( Fig. 6 ).
- the pressing member 185 is held to be swingable with the shaft member 185a as a center.
- One end of the compression spring 186 is attached to the support member 187.
- the support member 187 is fixed to the fixing portion HP.
- the other end of the compression spring 186 abuts against the pressing member 85.
- the pressing member 85 is pressed against the sub-intake cam 177 by a biasing force of the compression spring 186.
- the rotational resistance is generated between the stationary system and the sub-intake cam 177.
- the sub-intake cam 177 rotates with a delay relative to the intake cam 173 during the reverse rotation of the crankshaft 13.
- the sub-intake cam 177 can be stably moved to the start-up position using a simple configuration.
- Fig. 13 is a diagram for explaining the third modified example of a valve driver 17. As for the example of Fig. 13 , differences from the example of Figs. 5 and 6 will be described.
- the valve driver 17 of Fig. 13 includes an annular weight WT instead of the holder 179 and the friction member FR2 of Figs. 5 and 6 .
- the weight WT is provided at the sub-intake cam 177. In the present example, the weight WT is attached onto the outer peripheral surface of the storage 177b.
- 'I' is the moment of inertia of the sub-intake cam 177
- ' ⁇ ' is the angular acceleration of the camshaft 170
- 'T F ' is a drag torque of the sub-intake cam 177 with respect to the shaft portion 174 of the camshaft 170.
- the weight WT is provided, so that the moment of inertia of the sub-intake cam 177 increases.
- the drag torque T F depends on the rotational resistance generated between the one-way clutch 175 and the shaft portion 174. As described above, the one-way clutch 175 is rotatable in the forward direction Q1 with respect to the shaft portion 174. Therefore, during the reverse rotation of the camshaft 170, the drag torque T F is small. Thus, during the reverse rotation of the camshaft 170, the above formula (1) is satisfied, and the sub-intake cam 177 rotates with a delay relative to the camshaft 170.
- the moment of inertia of the sub-intake cam 177 and the rotational resistance between the shaft portion 174 and the one-way clutch 175 are set such that the sub-intake cam 177 rotates with a delay relative to the camshaft 170 by inertia.
- the sub-intake cam 177 can rotate with a delay while an increase in number of components is inhibited.
- a material tungsten, for example
- having a large specific gravity may be used as a material for the sub-intake cam 177, whereby the moment of inertia of the sub-intake cam 177 may be increased.
- the one-way clutch 175 and the friction member FR1 are provided, so that the sub-intake cam 177 is prevented from instantaneously moving from the start-up position to the normal position by the reaction force from the intake rocker arm RA1.
- the present invention is not limited to this.
- Fig. 14 is a perspective view showing the appearance of a valve driver 17 for explaining the fourth modified example.
- Fig. 15 is a cutaway perspective view of the valve driver 17 of Fig. 14 as viewed from a different position. As for the example of Figs. 14 and 15 , differences from the example of Figs. 5 and 6 will be described.
- the valve driver 17 of Figs. 14 and 15 includes a sub-cam member 210, a holding member 220 and a centrifugal member 230 instead of the one-way clutch 175, the sub-intake cam 177 and the friction member FR1 of Figs. 5 and 6 .
- the sub-cam member 210 includes a sub-intake cam 211, a rotation plate 212 and a projection piece 213.
- the sub-intake cam 211 has a cam profile similar to that of the sub-intake cam 177 of Figs. 5 and 6 .
- a rotation plate 212 has a disc shape with the axial center of the shaft portion 174 of the camshaft 170 as a center.
- the projection piece 213 is provided to project from a predetermined position in a peripheral edge of the rotation plate 212 towards the side opposite to the sub-intake cam 211 in the axis direction.
- the sub-cam member 210 is provided to be rotatable in a circumferential direction with respect to the shaft portion 174 of the camshaft 170.
- the sub-cam member 210 is configured such that the sub-intake cam 211 rotates with a delay relative to the intake cam 173.
- a member that generates the rotational resistance between the stationary system and the sub-cam member 210 is provided, so that the sub-intake cam 211 rotates with a delay relative to the intake cam 173.
- the moment of inertia of the sub-cam member 210 is set to be large, whereby the sub-intake cam 211 rotates with a delay relative to the intake cam 173.
- the holding member 220 includes disc-shaped holding plates 221, 222 and a cylindrical coupler 223 ( Fig. 15 ).
- the holding member 200 is fixed to the shaft portion 174 of the camshaft 170.
- Each of the holding plates 221, 222 has substantially the same diameter as that of the rotation plate 212 of the sub-cam member 210.
- the holding plates 221, 222 are at a constant distance from each other in the axis direction, and are coupled to each other via the coupler 223 ( Fig. 15 ).
- Cutouts 221a, 222a extending in a circular arc shape in the circumferential direction are respectively formed at outer peripheries of the holding plates 221, 222. In the axis direction, the cutouts 221a, 222a overlap with each other.
- the cutouts 221a, 222a constitute a positioner 220C.
- the projection piece 213 of the sub-cam member 210 is arranged in the positioner 220C. As described below, a range of the rotation of the sub-cam member 210 with respect to the camshaft 170 and the holding member 220 is restricted by the projection piece 213 and the positioner 220C.
- FIG. 15 the cutaway holding member 220 and the cutaway shaft portion 174 are shown.
- the hatching illustrates a cutaway sectional view.
- the holding plate 222 of the holding member 220 is not shown in Fig. 15 .
- the shaft portion 174 is inserted into the coupler 223 of the holding member 220.
- the holding pins 224, 225 extending in the axis direction are respectively provided to sandwich the coupler 223 between the holding plates 221, 222.
- the centrifugal member 230 is arranged between the holding plates 221, 222 and provided to extend in a substantially circumferential direction.
- a hole 230a is formed in the centrifugal member 230.
- the holding pin 224 of the holding member 220 is inserted into the hole 230a.
- An abutment portion 231 is provided at the end of the centrifugal member 230 on one side of the holding pin 224.
- a cutout 230b is formed at an outer periphery of the centrifugal member 230 on the other side of the holding pin 224.
- a projection 232 projecting in the axis direction is provided at an end of the centrifugal member 230 on the other side of the holding pin 224.
- One end and the other end of a tension spring 240 are respectively engaged with the holding pin 225 of the holding member 220 and the projection 232 of the centrifugal member 230.
- the tension spring 240 biases the centrifugal member 230 in a direction in which the projection 232 comes closer to the holding pin 225.
- a movement of a projection piece 213a of the sub-cam member 210 is restricted by the centrifugal member 230.
- Fig. 16 is a diagram for explaining a range of the rotation of the sub-cam member 210.
- the projection piece 213 of the sub-cam member 210 abuts against one end TC1 of the positioner 220C, so that the rotation of the sub-cam member 210 in the reverse direction Q2 with respect to the camshaft 170 and the holding member 220 is prevented.
- the entire cam nose 211T of the sub-intake cam 211 overlaps with the cam nose 173T of the intake cam 173 in the axis direction. That is, the sub-intake cam 211 is at the normal position.
- the projection piece 213 of the sub-cam member 210 abuts against the other end TC2 of the positioner 220C, so that the rotation of the sub-cam member 210 in the forward direction Q1 with respect to the camshaft 170 and the holding member 220 is prevented.
- the cam nose 211T of the sub-intake cam 211 and the cam nose 173T of the intake cam 173 deviate from each other by a constant angle in the circumferential direction. That is, the sub-intake cam 211 is at the start-up position.
- Fig. 17 is a diagram for explaining the swinging of the centrifugal member 230.
- a centrifugal force exerted on the centrifugal member 230 is small, an inner periphery of the centrifugal member 230 is maintained abutting against the outer peripheral surface of the coupler 223 by a biasing force of the tension spring 240 ( Fig. 15 ).
- a portion of the centrifugal member 230 on the one side of the holding pin 224 projects into the positioner 220C, and a portion of the centrifugal member 230 on the other side of the holding pin 224 is stored between the holding plates 221, 222.
- a position of the centrifugal member 220 is referred to as a low rotation position.
- the centrifugal member 230 is held at the low rotation position.
- the abutment portion 231 is positioned in the vicinity of the other end TC2 in the positioner 230C. Therefore, when the projection piece 213 is at the other end TC2 of the positioner 220C, the movement of the projection piece 213 is prevented by an abutment of the abutment portion 231 against the projection piece 213. Thus, the projection piece 213 is held at the other end TC2 of the positioner 220C. Therefore, the sub-intake cam 211 is held at the start-up position of Fig. 16(d) .
- a cutout 230b is positioned in the vicinity of the one end TC1 of the positioner 230C. Therefore, in the case where being at the one end TC1 of the positioner 220C, the projection piece 213 is fitted with the cutout 230b. Thus, the projection piece 213 is held at the one end TC1 of the positioner 220C. Therefore, the sub-intake cam 211 is held at the normal position of Fig. 16(b) .
- Figs. 18 to 22 are diagrams for explaining the operations of the intake cam 173 and the sub-intake cam 211 in the reverse rotation start-up operation.
- Figs. 18(a) , 19(a) , 20(a) , 21(a) and 22(a) the states of the intake cam 173, the sub-intake cam 211, the intake rocker arm RA1 and the intake valve 15 are shown.
- Figs. 18(b) , 19(b) , 20(b) , 21(b) and 22(b) the states of the projection piece 213 and the centrifugal member 230 are shown.
- the sub-intake cam 211 is at the normal position as shown in Fig. 18(a) . Further, as shown in Fig. 18(b) , the centrifugal member 230 is at the low rotation position, and the projection piece 213 is at the one end TC1 of the positioner 220C.
- the camshaft 170 rotates in the reverse direction Q2
- the intake cam 173 pushes up the one end of the intake rocker arm RA1 as shown in Fig. 19(a) .
- the intake valve 15 is lifted.
- the sub-cam member 210 rotates with a delay relative to the intake cam 173.
- the sub-cam member 210 rotates in the forward direction Q1 with respect to the shaft portion 174, and the sub-intake cam 211 moves towards the start-up position. Further, as shown in Fig. 19(b) , with the centrifugal member 230 held at the low rotation position, the projection piece 213 of the sub-cam member 210 moves from the one end TC1 towards the other end TC2 of the positioner 220C.
- the projection piece 213 pushes down a portion of the centrifugal member 230 on the one side of the holding pin 224 and moves to the other end TC2 of the positioner 220C by the force applied from the intake rocker arm RA1 to the sub-intake cam 211.
- the sub-cam member 210 rotates in the reverse direction Q2 with respect to the camshaft 170, and the sub-intake cam 211 moves to the start-up position.
- the projection piece 213 moves to the one end TC1 of the positioner 220C.
- the projection piece 213 pushes down a portion of the centrifugal member 230 on the other side of the holding pin 224 and moves to the one end TC1 of the positioner 220C by the force in the reverse direction Q2 applied from the intake rocker arm RA1 to the sub-intake cam 211.
- the projection piece 213 is fitted with the cutout 230b of the centrifugal member 230.
- the projection piece 213 is prevented from moving from the one end TC1 of the positioner 220C. Therefore, the sub-cam member 210 is prevented from rotating in the forward direction Q1 with respect to the camshaft 170, and the sub-intake cam 211 is held at the normal position. Thus, during the normal operation, the generation of an abnormal noise caused by the movement of the sub-cam member 210 is prevented.
- the sub-intake cam 211 is held at the start-up position by the centrifugal member 230. After the combustion of the fuel-air mixture and during the forward rotation of the crankshaft 13, the sub-intake cam 211 is held at the normal position. Thus, any unnecessary movement of the sub-intake cam 211 is prevented using a simple configuration for utilizing a centrifugal force. Therefore, the generation of an abnormal noise caused by the movement of the sub-intake cam 211 is prevented.
- the present invention is not limited to this.
- the engine 10 may be configured such that the intake cam 173 and the sub-intake cams 177, 211 directly drive the intake valve 15, and may be configured such that the exhaust cam 172 directly drives the exhaust valve 16.
- the exhaust cam 172, the intake cam 173 and the sub-intake cams 177, 211 are respectively provided at the common camshaft 170.
- the present invention is not limited to this.
- a camshaft for the intake cam 173 and the sub-intake cams 177, 211 and a camshaft for the exhaust cam 172 may be separately provided.
- the above-mentioned embodiment is an example in which the present invention is applied to the motorcycle.
- the present invention is not limited to this.
- the present invention may be applied to another straddled vehicle such as a motor tricycle or an ATV (All Terrain Vehicle) or any another vehicle such as a four-wheeled automobile.
- the engine system 200 is an example of an engine system
- the engine 10 is an example of an engine
- the rotary electrical machine 14 is an example of a rotation driver
- the crankshaft 13 is an example of a crankshaft
- the ECU 6 is an example of a controller
- the valve driver 17 is an example of a valve driver.
- the camshaft 170 is an example of a shaft portion
- the intake cam 173 is an example of a first intake cam
- the sub-intake cams 177, 211 are examples of a second intake cam
- the normal position is an example of a first position
- the start-up position is an example of a second position.
- the cylinder head CH or the arm shaft SH2 is an example of a stationary member
- the friction member FR2 is an example of a friction member
- the one-way clutch 175 is an example of a one-way clutch
- the friction member FR1 is an example of a resistance generation member
- the centrifugal member 230 is an example of a centrifugal member
- the intake rocker arm RA1 is an example of a rocker arm.
- the motorcycle 100 is an example of a vehicle
- the body 1 is an example of a main body
- the rear wheel 7 is an example of a drive wheel.
- the present invention can be effectively utilized for various types of engine systems.
Abstract
Description
- The present invention relates to an engine system and a vehicle including the engine system.
- During start-up of an engine, a large torque is required in order for a crank angle to exceed an angle corresponding to a first compression top dead center. In an engine system described in
Patent Document 1, during start-up of an engine, a fuel-air mixture is introduced into a combustion chamber while a crankshaft rotates in reverse. With the fuel-air mixture in the combustion chamber compressed by the reverse rotation of the crankshaft, the fuel-air mixture in the combustion chamber is ignited. The rotation of the crankshaft is driven in a forward direction by energy of the combustion of the fuel-air mixture, so that a forward torque of the crankshaft is increased. Thus, the startability of the engine is enhanced. - A movement direction of a piston during the reverse rotation of the crankshaft is opposite to a movement direction of the piston during the forward rotation of the crankshaft. Therefore, in order to introduce a fuel-air mixture into the combustion chamber during the reverse rotation of the crankshaft, it is necessary that an intake valve is lifted in a range of a crank angle different from that of a normal intake stroke. In the above-mentioned engine system, a sub-intake cam for lifting the intake valve during the reverse rotation of the crankshaft is provided in addition to a main intake cam for lifting the intake valve during the forward rotation of the crankshaft.
- A sub-intake cam is provided to be rotatable in a constant angular range with respect to a shaft portion of a camshaft. When the sub-intake cam is at a first position with respect to the shaft member, a cam nose of the sub-intake cam does not overlap with a cam nose of the main intake cam, so that the sub-intake cam lifts the intake valve separately from the main intake cam. When the sub-intake cam is at a second position with respect to the shaft portion, the cam nose of the sub-intake cam overlaps with the cam nose of the main intake cam, so that the sub-intake cam does not act on the intake valve. The sub-intake cam is biased by a torsion coil spring towards a first position.
- During the reverse rotation of the crankshaft, the sub-intake cam pushes up a rocker arm at the first position, thereby lifting the intake valve. On the other hand, during the forward rotation of the crankshaft, the sub-intake cam is pushed back to the second position by a counterforce of the rocker arm. Therefore, the sub-intake cam does not lift the intake valve. When the rocker arm moves away from the sub-intake cam, the sub-intake cam moves to the first position by a biasing force of the torsion coil spring.
Patent Document 1:JP 2014-77405 A - In a configuration described in the above-mentioned
Patent Document 1, during the forward rotation of the crankshaft, the sub-intake cam moves between the first position and the second position by a counterforce of the rocker arm and a biasing force of the torsion coil spring each time the camshaft rotates once. Thus, various abnormal noises such as a contact noise of the sub-intake cam caused by the rocker arm is continuously generated during the normal operation. - An object of the present invention is to provide an engine system and a vehicle in which startability of an engine can be enhanced while the generation of an abnormal noise is prevented.
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- (1) An engine system according to one aspect of the present invention includes an engine, a rotation driver that rotates a crankshaft of the engine in a forward direction and a reverse direction, and a controller, wherein the controller controls the engine and the rotation driver by rotating the crankshaft in the reverse direction and then combusting a fuel-air mixture in a combustion chamber of the engine such that the crankshaft is driven in the forward direction, the engine includes a valve driver that lifts an intake valve, the valve driver includes a shaft portion provided to rotate in the forward direction and the reverse direction in conjunction with a rotation of the crankshaft in the forward direction and the reverse direction, and first and second intake cams provided at the shaft portion, the first intake cam acts on the intake valve in a range of a crank angle corresponding to an intake process by integrally rotating with the shaft portion, the second intake cam is configured to be movable between a first position and a second position in a circumferential direction of the shaft portion by being rotatable within a constant angular range with respect to the shaft portion, the second intake cam overlaps with the first intake cam in an axis direction of the shaft portion when being at the first position, and acts on the intake valve within at least a part of a range of the crank angle corresponding to an exhaust stroke when being at the second position, and the second intake cam, during the rotation of the crankshaft in the forward direction, is at the first position and does not act on the intake valve, and the second intake cam, during the rotation of the crankshaft in the reverse direction, moves to the second position by rotating with a delay relative to the first intake cam and acts on the intake valve.
In this engine system, the second intake cam is at the first position and does not act on the intake valve during the rotation of the crankshaft in the forward direction, and the second intake cam moves to the second position and acts on the intake valve during the rotation of the crankshaft in the reverse direction. The second intake cam acts on the intake valve in a range of the crank angle corresponding to the exhaust stroke at the second position, so that a fuel-air mixture is introduced into the combustion chamber of the engine while the crankshaft rotates in the reverse direction. The crankshaft is driven in the forward direction by the combustion of the fuel-air mixture. Thus, the startability of the engine can be enhanced.
During the rotation of the crankshaft in the reverse direction, the second intake cam moves to the second position by rotating with a delay relative to the first intake cam. Thus, it is possible to move the second intake cam to the second position during the rotation of the crankshaft in the reverse direction without complicating a configuration of the valve driver. Further, because the second intake cam is not biased by a biasing member at the second position, the second intake cam can be held at the first position during the rotation of the crankshaft in the forward direction. Thus, it is not necessary to move the second intake cam from the second position to the first position each time the shaft portion rotates once. Therefore, the generation of an abnormal noise such as a contact noise caused by the movement of the second intake cam is prevented. - (2) The valve driver may further include a stationary member, and a rotational resistance generation mechanism that generates a rotational resistance between the stationary member and the second intake cam, and during the rotation of the crankshaft in the reverse direction, the rotational resistance generated by the rotational resistance generation mechanism may be larger than the rotational resistance between the shaft portion and the second intake cam.
In this case, during the rotation of the crankshaft in the reverse direction, the second intake cam rotates with a delay relative to the first intake cam by the rotational resistance generated by the rotation resistance generation mechanism. Thus, the second intake can be stably moved to the second position using a simple configuration. - (3) The rotational resistance generation mechanism may include a friction member that generates a friction between the stationary member and the second intake cam. In this case, the rotational resistance can be generated between the stationary member and the second intake cam using a simple configuration and at low cost.
- (4) The moment of inertia of the second intake cam and the rotational resistance between the shaft portion and the second intake cam may be set such that the second intake cam rotates with a delay relative to the first intake cam by inertia. In this case, it is possible to delay the rotation of the second intake cam while inhibiting an increase in number of components.
- (5) The second intake cam may be held at the shaft portion via a rolling bearing. In this case, the rotational resistance between the shaft portion and the second intake cam can be reduced using a simple configuration, and the rotation of the second intake cam can be delayed.
- (6) The valve driver may further include a one-way clutch that does not transmit the rotation of the second intake cam in the forward rotation with respect to the shaft portion from the second intake cam to the shaft portion, and transmits the rotation of the second intake cam in the reverse direction with respect to the shaft portion from the second intake cam to the shaft portion, and a resistance generation member that generates the rotational resistance between the one-way clutch and the shaft portion or between the one-way clutch and the second intake cam.
In this case, the rotation of the second intake cam in the forward direction with respect to the shaft portion is not transmitted from the second intake cam to the shaft portion by the one-way clutch. Therefore, during the rotation of the crankshaft in the reverse direction, a movement of the second intake cam to the second position is not prevented by the one-way clutch.
On the other hand, the rotation of the second intake cam in the reverse direction with respect to the shaft portion is transmitted from the second intake cam to the shaft portion by the one-way clutch. Therefore, during the rotation of the crankshaft in the reverse direction, even when a counterforce in the reverse direction is applied from the intake valve to the second intake cam, the second intake cam does not instantaneously move from the second position to the first position.
Because the rotational resistance is generated by the resistance generation member provided between the one-way clutch and the shaft portion or between the one-way clutch and the second intake cam, the second intake cam or the one-way clutch gently rotates in the forward direction with respect to the shaft portion while receiving the rotational resistance generated by the resistance generation member. Thus, the generation of an abnormal noise such as a contact noise caused by an instantaneous movement of the second intake cam is prevented. - (7) The valve driver may further include a centrifugal member, which is provided to rotate together with the shaft portion and is provided to be movable between a low speed position and a high speed position with respect to the shaft portion depending on a magnitude of a centrifugal force generated by the rotation of the shaft portion, and the centrifugal member, before the combustion of the fuel-air mixture in the combustion chamber and during the rotation of the crankshaft in the reverse direction, may hold the second intake cam at the second position while being at the low speed position, and after the combustion of the fuel-air mixture in the combustion chamber and during the rotation of the crankshaft in the forward direction, may hold the second intake cam at the first position while being at the high speed position.
In this case, before the combustion of the fuel-air mixture and during the rotation of the crankshaft in the reverse direction, the rotation speed of the shaft portion of the valve driver is low, so that the centrifugal member is held at the low speed position. When the fuel-air mixture is combusted, the rotation speeds of the crankshaft and the shaft portion of the valve driver instantaneously increase. Therefore, the centrifugal member moves to the high speed position. The centrifugal member holds the second intake cam at the second position while being at the low speed position, and holds the second intake cam at the first position while being at the high speed position. Thus, any unnecessary movement of the second intake cam is prevented using a simple configuration utilizing a centrifugal force. Therefore, the generation of an abnormal noise caused by the movement of the second intake cam is prevented. - (8) The valve driver may further include a rocker arm abutting against the first and second intake cams, and the rocker arm, during the rotation of the crankshaft in the forward direction, may act on the second intake cam such that the second intake cam moves to the first position, and during the rotation of the crankshaft in the reverse direction, may act on the second intake cam such that the second intake cam moves to the second position.
In this case, during the rotation of the crankshaft in the forward direction, the second intake cam can be appropriately moved to the first position. Further, during the rotation of the crankshaft in the reverse direction, even in the case where the second intake cam rotates with only a small delay relative to the first intake cam, the second intake cam can be appropriately moved to the second position. - (9) A vehicle according to another aspect of the present invention includes a main body having a drive wheel, and the engine system, described above, that generates a motive power for rotating the drive wheel.
- In this vehicle, the above-mentioned engine system is used, so that startability of the engine can be enhanced while the generation of an abnormal noise is prevented.
- The present invention enables startability of the engine to be enhanced while preventing the generation of an abnormal noise.
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- [
FIG. 1] Fig. 1 is a schematic side view showing a schematic configuration of a motorcycle according to one embodiment of the present invention. - [
FIG. 2] Fig. 2 is a schematic diagram for explaining a configuration of an engine system. - [
FIG. 3] Fig. 3 is a diagram for explaining a normal operation of an engine unit. - [
FIG. 4] Fig. 4 is a diagram for explaining a reverse rotation start-up operation of the engine unit. - [
FIG. 5] Fig. 5 is an exploded perspective view of a valve driver. - [
FIG. 6] Fig. 6 is a cross-sectional view of the valve driver and its peripheral portions. - [
FIG. 7] Fig. 7 is a diagram for explaining a relationship among the valve driver, an intake valve and an exhaust valve. - [
FIG. 8] Fig. 8 is a diagram for explaining a rotatable angular range of a sub-intake cam. - [
FIG. 9] Fig. 9 is a diagram for explaining the operations of an intake cam and the sub-intake cam in a reverse rotation start-up operation. - [
FIG. 10] Fig. 10 is a diagram for explaining the operations of the intake cam and the sub-intake cam in the reverse rotation start-up operation. - [
FIG. 11] Fig. 11 is a diagram for explaining a first modified example of a valve driver. - [
FIG. 12] Fig. 12 is a diagram for explaining a second modified example of a valve driver. - [
FIG. 13] Fig. 13 is a diagram for explaining a third modified example of a valve driver. - [
FIG. 14] Fig. 14 is a perspective view showing the appearance of a valve driver for explaining a fourth modified example. - [
FIG. 15] Fig. 15 is a cutaway perspective view of the valve driver ofFig. 14 as viewed from a different position. - [
FIG. 16] Fig. 16 is a diagram for explaining a rotation range of a sub-cam member. - [
FIG. 17] Fig. 17 is a diagram for explaining the swinging of a centrifugal member. - [
FIG. 18] Fig. 18 is a diagram for explaining the operations of an intake cam and a sub-intake cam in a reverse rotation start-up operation. - [
FIG. 19] Fig. 19 is a diagram for explaining the operations of the intake cam and sub-intake cam in the reverse rotation start-up operation. - [
FIG. 20] Fig. 20 is a diagram for explaining the operations of the intake cam and the sub-intake cam in the reverse rotation start-up operation. - [
FIG. 21] Fig. 21 is a diagram for explaining the operations of the intake cam and the sub-intake cam in the reverse rotation start-up operation. - [
FIG. 22] Fig. 22 is a diagram for explaining the operations of the intake cam and the sub-intake cam in the reverse rotation start-up operation. - An engine system and a motorcycle according to embodiments of the present invention will be described below with reference to the drawings. The motorcycle is one example of a vehicle.
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Fig. 1 is a schematic side view showing a schematic configuration of the motorcycle according to one embodiment of the present invention. In themotorcycle 100 ofFig. 1 , afront fork 2 is provided at a front portion of avehicle body 1 to be swingable to the right and the left. Ahandle 4 is attached to an upper end of thefront fork 2, and afront wheel 3 is rotatably attached to a lower end of thefront fork 2. - A
seat 5 is provided at a substantially central upper portion of thevehicle body 1. An ECU (Engine Control Unit) 6, a battery BT and an engine unit EU are provided below theseat 5. TheECU 6, the battery BT and the engine unit EU constitute anengine system 200. Arear wheel 7 is rotatably attached to a lower portion of a rear end of thevehicle body 1. The rotation of therear wheel 7 is driven by the motive power generated by the engine unit EU. -
Fig. 2 is a schematic diagram for explaining a configuration of theengine system 200. As shown inFig. 2 , the engine unit EU includes anengine 10 and a rotaryelectrical machine 14. Theengine 10 includes a cylinder CY, apiston 11, a connectingrod 12, acrankshaft 13, anintake valve 15, anexhaust valve 16, avalve driver 17, aninjector 18 and anignition device 19. - The
piston 11 is provided to be reciprocatable in the cylinder CY and connected to thecrankshaft 13 via the connectingrod 12. Thecrankshaft 13 is provided with the rotaryelectrical machine 14. The rotaryelectrical machine 14, which is connected to the battery BT, can drive thecrankshaft 13 in a forward direction or a reverse direction by electrical power supplied from the battery BT, and can charge the battery BT by electrical power generated by the rotation of thecrankshaft 13. The forward direction is a direction in which thecrankshaft 13 rotates during a normal operation of theengine 10, whereas the reverse direction is a direction opposite to the forward direction. The rotaryelectrical machine 14 transmits a torque directly to thecrankshaft 13 without a reduction gear. The rotation of thecrankshaft 13 in the forward direction (forward rotation) is transmitted to therear wheel 7, so that the rotation of therear wheel 7 is driven. A starter motor and a generator may be provided separately instead of the rotaryelectrical machine 14. - A
combustion chamber 31a is divided into sections by the cylinder CY and thepiston 11. Thecombustion chamber 31a communicates with anintake passage 22 through anintake port 21 and communicates with anexhaust passage 24 through anexhaust port 23. Anintake valve 15 is provided to open and close theintake port 21, and anexhaust valve 16 is provided to open and close theexhaust port 23. Theintake valve 15 and theexhaust valve 16 are driven by thevalve driver 17. Details of thevalve driver 17 will be described below. - A throttle valve TV for adjusting a flow rate of air flowing in from the outside is provided in the
intake passage 22. Theinjector 18 is configured to inject fuel into theintake passage 22. Theignition device 19 is configured to ignite a fuel-air mixture in thecombustion chamber 31a. - The fuel injected by the
injector 18 is mixed with air and then guided to thecombustion chamber 31a, and the fuel-air mixture in thecombustion chamber 31a is ignited by theignition device 19. The reciprocating motion of thepiston 11 due to the combustion of the fuel-air mixture is converted into the rotation motion of thecrankshaft 13. The rotation force of thecrankshaft 13 is transmitted to therear wheel 7 ofFig. 1 , so that therear wheel 7 is driven. - The
ECU 6 includes a CPU (Central Processing Unit) and a memory, for example. A microcomputer may be used instead of the CPU and the memory. TheECU 6 is electrically connected with amain switch 40, astarter switch 41, anintake pressure sensor 42, acrank angle sensor 43 and acurrent sensor 44. Themain switch 40 is provided below thehandle 4 ofFig. 1 , for example, and thestarter switch 41 is provided on thehandle 4 ofFig. 1 , for example. Themain switch 40 and thestarter switch 41 are operated by a rider. Theintake pressure sensor 42 detects a pressure in theintake passage 22. Thecrank angle sensor 43 detects a crank angle indicating a rotation position of thecrankshaft 13. Thecurrent sensor 44 detects a current flowing in the rotaryelectrical machine 14. - The operations or actuations of the
main switch 40 and thestarter switch 41 are supplied as operation signals to theECU 6, and the results of detection by theintake pressure sensor 42, thecrank angle sensor 43 and thecurrent sensor 44 are supplied as detection signals to theECU 6. TheECU 6 controls the rotaryelectrical machine 14, theinjector 18 and theignition device 19 based on the supplied operation signal and the supplied detection signal. - The
engine 10 is started when themain switch 40 ofFig. 2 is turned on and thestarter switch 41 is turned on, whereas theengine 10 is stopped when themain switch 40 ofFig. 2 is turned off. Start-up of theengine 10 refers to a combustion in thecombustion chamber 31a being started by a start of fuel injection by theinjector 18 and a start of ignition by theignition device 19. Stopping of theengine 10 refers to the combustion in thecombustion chamber 31a being stopped by the stoppage of at least one of the fuel injection by theinjector 18 and the ignition by theignition device 19. - Also, when a predetermined idle stop condition is satisfied, the
engine 10 may be automatically stopped. After that, when a predetermined re-start condition is satisfied, theengine 10 may be automatically re-started. The idle stop condition may include a condition that relates to at least one of, for example, a throttle opening (a degree of opening of a throttle valve TV), a vehicle speed and a rotation speed of the engine 10 (a rotation speed of the crankshaft 13), and may further include another condition such as a condition that a brake lever is operated. The re-start condition refers to, for example, the throttle opening being larger than 0 when an accelerator grip is operated, and may include another condition such as a condition that an operation of the brake lever is released. - The engine unit EU performs a reverse rotation start-up operation during the start-up of the
engine 10. Thereafter, the engine unit EU performs a normal operation that includes an intake stroke, a compression stroke, an expansion stroke and an exhaust stroke.Fig. 3 is a diagram for explaining the normal operation of the engine unit EU.Fig. 4 is a diagram for explaining the reverse rotation start-up operation of the engine unit EU. - In the following description, a top dead center through which the
piston 11 passes at the time of shifting from the compression stroke to the expansion stroke is referred to as a compression top dead center, and a top dead center through which thepiston 11 passes at the time of shifting from the exhaust stroke to the intake stroke is referred to as an exhaust top dead center. A bottom dead center through which thepiston 11 passes at the time of shifting from the intake stroke to the compression stroke is referred to as an intake bottom dead center, and a bottom dead center through which thepiston 11 passes at the time of shifting from the expansion stroke to the exhaust stroke is referred to as an expansion bottom dead center. - In
Figs. 3 and4 , the range of the crank angle which is equivalent to two rotations (720 degrees) of thecrankshaft 13 is represented by one circle. The two rotations of thecrankshaft 13 are equivalent to one cycle of theengine 10. Thecrank angle sensor 43 ofFig. 2 detects a rotation position in a range in which thecrankshaft 13 rotates once (360 degrees). Based on the pressure in theintake passage 22 detected by theintake pressure sensor 42, theECU 6 determines to which one of the two rotations of thecrankshaft 13 equivalent to one cycle of theengine 10 the angle detected by thecrank angle sensor 43 corresponds. Thus, theECU 6 can acquire the rotation position in the range of two rotations (720 degrees) of thecrankshaft 13 as the crank angle. - In
Figs. 3 and4 , an angle A0 is a crank angle when the piston 11 (Fig. 2 ) is positioned at the exhaust top dead center, an angle A2 is a crank angle when thepiston 11 is positioned at the compression top dead center, an angle A1 is a crank angle when thepiston 11 is positioned at the intake bottom dead center, and an angle A3 is a crank angle when thepiston 11 is positioned at the expansion bottom dead center. An arrow R1 indicates a direction in which the crank angle changes during the forward rotation of thecrankshaft 13, and an arrow R2 indicates a direction in which the crank angle changes during the reverse rotation of thecrankshaft 13. Arrows P1 to P4 indicate directions in which thepiston 11 moves during the forward rotation of thecrankshaft 13. Arrows P5 to P8 indicate directions in which thepiston 11 moves during the reverse rotation of thecrankshaft 13. - The normal operation of the engine unit EU will be described with reference to
Fig. 3 . In the normal operation, the crankshaft 13 (Fig. 2 ) rotates forwardly, so that the crank angle changes in the direction of the arrow R1. In this case, as indicated by the arrows P1 to P4, the piston 11 (Fig. 2 ) is lowered in a range from the angle A0 to the angle A1, raised in a range from the angle A1 to the angle A2, lowered in a range from the angle A2 to the angle A3, and raised in a range from the angle A3 to the angle A0. - At an angle A11, the fuel is injected into the intake passage 22 (
Fig. 2 ) by the injector 18 (Fig. 2 ). In the forward direction, the angle A11 is positioned at a further advanced angle than the angle A0. The intake port 21 (Fig. 2 ) is subsequently opened by the intake valve 15 (Fig. 2 ) in a range from an angle A12 to an angle A13. Thus, a fuel-air mixture including air and fuel is introduced into thecombustion chamber 31a (Fig. 2 ) through theintake port 21. In the forward direction, the angle A12 is positioned at a further retarded angle than the angle A11 and at a further advanced angle than the angle A0, and the angle A13 is positioned at a further retarded angle than the angle A1. - Then, at an angle A14, the fuel-air mixture in the
combustion chamber 31a (Fig. 2 ) is ignited by the ignition device 19 (Fig. 2 ). In the forward direction, the angle A14 is positioned at a further retarded angle than the angle A13 and at a further advanced angle than the angle A2. The fuel-air mixture is ignited, so that the fuel-air mixture is combusted in thecombustion chamber 31a. Thereafter, the exhaust port 23 (Fig. 2 ) is opened by the exhaust valve 16 (Fig. 2 ) in a range from an angle A15 to an angle A16. Thus, the combusted gas is discharged from thecombustion chamber 31a through theexhaust port 23. In the forward direction, the angle A15 is positioned at a further advanced angle than the angle A3, and the angle A16 is positioned at a further retarded angle than the angle A0. - The reverse rotation start-up operation of the engine unit EU will be described with reference to
Fig. 4 . In the present embodiment, the crank angle is adjusted to an angle A20 by the forward rotation of thecrankshaft 13 before the reverse rotation start-up operation. In the forward direction, the angle A20 is positioned at a further retarded angle than the angle A1 and at a further advanced angle than the angle A2. - In the reverse rotation start-up operation, the crank angle changes in a direction of the arrow R2 by the reverse rotation of the
crankshaft 13 by the rotary electrical machine 14 (Fig. 2 ). In this case, as denoted by the arrows P5 to P8, thepiston 11 is lowered in a range from the angle A2 to the angle A1, raised in a range from the angle A1 to the angle A0, lowered in the range from the angle A0 to the angle A3, and raised in a range from the angle A3 to the angle A2. The direction in which thepiston 11 moves during the reverse rotation of thecrankshaft 13 is opposite to the direction in which thepiston 11 moves during the forward rotation of thecrankshaft 13. - In the present example, also during the reverse rotation of the
crankshaft 13, theintake port 21 is opened in a range from the angle A13 to the angle A12, and theexhaust port 23 is opened in a range from the angle A16 to the A15 similarly to during the forward rotation. - At an angle A23, fuel is injected to the intake passage 22 (
Fig. 2 ) by the injector 18 (Fig. 2 ). In the reverse direction, the angle A23 is positioned at a further retarded angle than the angle A1 and at a further advanced angle than the angle A0. The intake port 21 (Fig. 2 ) is opened by the intake valve 15 (Fig. 2 ) in a range from an angle A21 to an angle A22. In the reverse direction, the angles A21, A21 are positioned in the range, from the angle A0 to the angle A3, corresponding to the exhaust stroke during the normal operation. In the range from the angle A1 to the angle A0, thepiston 11 is raised. Therefore, even when theintake port 21 is opened in the range from the angle A13 to the angle A12, fuel and air are hardly introduced into thecombustion chamber 31a. On the other hand, in the range from the angle A0 to the angle A3, thepiston 11 is lowered, so that theintake port 21 is opened in a range from the angle A21 to the angle A22. Thus, the fuel-air mixture including air and fuel is introduced into thecombustion chamber 31a through theintake port 21 from theintake passage 22. - As the crank angle comes closer to the angle A2, the fuel-air mixture introduced into the
combustion chamber 31a is compressed. At an angle A31, the fuel-air mixture in thecombustion chamber 31a is ignited by the ignition device 19 (Fig. 2 ), and a direction in which thecrankshaft 13 is driven by the rotaryelectrical machine 14 is switched from the reverse direction to the forward direction. In the reverse direction, the angle A31 is positioned at a further retarded angle than the angle A3 and at a further advanced angle than the angle A2. For example, when a current of the rotaryelectrical machine 14 detected by thecurrent sensor 44 ofFig. 2 reaches a threshold value, the fuel-air mixture is ignited by theignition device 19. In this case, thecrankshaft 13 is driven in the forward direction by the combustion of the fuel-air mixture, so that a forward torque of thecrankshaft 13 is increased. Thus, the crank angle can exceed the angle A2 corresponding to the first compression top dead center. In the case where the crank angle can exceed the angle A2 corresponding to the first compression top dead center only by energy of combustion, thecrankshaft 13 does not have to be driven in the forward direction by the rotaryelectrical machine 14. Thereafter, the engine unit EU is shifted to the above-mentioned normal operation. - A specific example of the configuration of the
valve driver 17 will be described.Fig. 5 is an exploded perspective view of thevalve driver 17, andFig. 6 is a cross-sectional view of thevalve driver 17 and its peripheral portions. - As shown in
Figs. 5 and6 , thevalve driver 17 includes acamshaft 170, a one-way clutch 175, asub-intake cam 177, a friction member FR1, aholder 179, a friction member FR2, an intake rocker arm RA1 and an exhaust rocker arm RA2. - As shown in
Fig. 5 , thecamshaft 170 includes ashaft portion 171, anexhaust cam 172, anintake cam 173 and ashaft portion 174. Theshaft portions exhaust cam 172 and theintake cam 173 sandwiched therebetween. An axial center of theshaft portion 171 and an axial center of theshaft portion 174 are positioned on a common straight line. In the following description, an axis direction refers to a direction in parallel with the axial centers of theshaft portions shaft portions exhaust cam 172 and theintake cam 173 respectively have predetermined cam profiles and are provided between theshaft portions cutout 173a is formed in a peripheral edge of one surface of theintake cam 173. - The one-
way clutch 175 is of cylindrical shape. The one-way clutch 175 is rotatable in one direction of the circumferential direction with respect to theshaft portion 174, and is non-rotatable in the opposite direction. A rotation direction of the one-way clutch 175 will be described below. - The
sub-intake cam 177, the friction member FR1, theholder 179 and the friction member FR1 are respectively provided to be annular. Thesub-intake cam 177 has a predetermined cam profile. Aprojection piece 177a is provided at one surface of thesub-intake cam 177. As described below, a rotatable angular range of thesub-intake cam 177 with respect to theshaft portion 174 is restricted by theprojection piece 177a and thecutout 173a of theintake cam 173. The range of the rotation of thesub-intake cam 177 will be described below. Acylindrical storage 177b is provided on the other surface of thesub-intake cam 177. The friction member FR1 is stored in thestorage 177b. Theholder 179 holds the friction member FR2. The friction members FR1, FR2 are respectively elastic. For example, an oil seal made of synthetic rubber or the like is used as the friction member FR1, FR2. - The intake rocker arm RA1 is provided to extend in a direction substantially orthogonal to the axis direction and on one side of the
camshaft 170. The exhaust rocker arm RA2 is provided to extend in a direction substantially orthogonal to the axis direction and on the other side of thecamshaft 170. The intake rocker arm RA1 and the exhaust rocker arm RA2 are provided to be respectively swingable with arm shafts SH1, SH2 (seeFig. 7 , described below) in parallel with the axis direction as centers. A roller RL1 is attached to one end of the intake rocker arm RA1, and a roller RL2 is attached to one end of the exhaust rocker arm RA2. - As shown in
Fig. 6 , thecamshaft 170 is held by the bearings B1, B2 to be rotatable about an axial center AC of theshaft portions engine 10. An inner peripheral surface of the bearing B1 abuts against an outer peripheral surface of theshaft portion 171, and an inner peripheral surface of the bearing B2 abuts against an outer peripheral surface of theshaft portion 174. The roller RL1 of the intake rocker arm RA1 abuts against theintake cam 173, and the roller RL2 of the exhaust rocker arm RA2 abuts against theexhaust cam 172. Further, a slipper surface SS is provided in a portion of the intake rocker arm RA1 adjacent to the roller RL1 in the axis direction. The slipper surface SS abuts against thesub-intake cam 177. - The one-
way clutch 175 is attached onto the outer peripheral surface of theshaft portion 174. Thesub-intake cam 177 is attached onto an outer peripheral surface of the one-way clutch 175 to be adjacent to theintake cam 173. Theholder 179 is fixed to the cylinder head CH to be adjacent to thesub-intake cam 177 and partially surround the outer peripheral surface of the one-way clutch 175. - An outer periphery of the friction member FR1 is fixed to the
storage 177b of thesub-intake cam 177, and an inner periphery of the friction member FR1 is pressed against the outer peripheral surface of the one-way clutch 175. Thus, a rotational resistance is generated between thesub-intake cam 177 and the one-way clutch 175 by the friction member FR1. The inner periphery of the friction member FR1 may be fixed to the outer peripheral surface of the one-way clutch 175, and the outer periphery of the friction member FR1 may be pressed against an inner peripheral surface of thestorage 177b of thesub-intake cam 177. A similar rotational resistance can be generated also in this case. - The
holder 179 is fixed to the cylinder head CH, thereby not moving in conjunction with the rotation of thecamshaft 170. Hereinafter, a part of the engine unit EU that does not move in conjunction with the rotation of thecamshaft 170 is referred to as a stationary system. An outer periphery of the friction member FR2 is fixed to theholder 179, and an inner periphery of the friction member FR2 is pressed against the outer periphery of the one-way clutch 175. Therefore, the rotational resistance is generated between the stationary system and the one-way clutch 175 by the friction member FR2. The inner periphery of the friction member FR2 may be fixed to the outer peripheral surface of the one-way clutch 175, and the outer periphery of the friction member FR2 may be pressed against the inner peripheral surface of theholder 179. A similar rotational resistance can be generated also in this case. The rotational resistance generated by the friction member FR2 is smaller than the rotational resistance generated by the friction member FR1. -
Fig. 7 is a diagram for explaining a relationship among thevalve driver 17, theintake valve 15 and theexhaust valve 16. As shown inFig. 7 , the intake rocker arm RA1 is provided to be swingable with the arm shaft SH1 as a center, and the exhaust rocker arm RA2 is provided to be swingable with the arm shaft SH2 as a center. An abutment member AD1 is attached to an end opposite to the roller RL1 of the intake rocker arm RA1. The abutment member AD1 abuts against an upper end of theintake valve 15. An abutment member AD2 is attached to an end opposite to the roller RL2 of the exhaust rocker arm RA2. The abutment member AD2 abuts against an upper end of theexhaust valve 16. - The
intake valve 15 is biased in a direction of closing the intake port 21 (Fig. 2 ) by avalve spring 15a. By a biasing force of thevalve spring 15a, theintake valve 15 is pressed against the abutment member AD1, and the roller RL1 of the intake rocker arm RA1 is pressed against theintake cam 173. Further, the slipper surface SS of the intake rocker arm RA1 is pressed against the sub-intake cam 177 (seeFig. 6 ). Theexhaust valve 16 is biased in a direction of closing the exhaust port 23 (Fig. 2 ) by thevalve spring 16a. By a biasing force of thevalve spring 16a, theexhaust valve 16 is pressed against the abutment member AD2, and the roller RL2 of the exhaust rocker arm RA2 is pressed against theexhaust cam 172. - Hereinafter, a rotation direction of the
camshaft 170 during the forward rotation of the crankshaft 13 (Fig. 2 ) is referred to as the forward direction (a direction Q1 ofFig. 7 ), and a rotation direction of thecamshaft 170 during the reverse rotation of the crankshaft 13 (Fig. 2 ) is referred to as the reverse direction (a direction Q2 ofFig. 7 ). Thecamshaft 170 rotates forwardly or in reverse, whereby theintake cam 173 and thesub-intake cam 177 swing the intake rocker arm RA1, and theexhaust cam 172 swings the exhaust rocker arm RA2. Thus, theintake valve 15 opens and closes theintake port 21, and theexhaust valve 16 opens and closes theexhaust port 23. - The one-
way clutch 175 ofFigs. 5 and6 is rotatable in the forward direction Q1 and non-rotatable in the reverse direction Q2 with respect to theshaft portion 174. Specifically, the rotational resistance exerted on the one-way clutch 175 from theshaft portion 174 in the reverse direction Q2 is significantly small, and the rotational resistance exerted on the one-way clutch 175 from theshaft portion 174 in the forward direction Q1 is significantly large. The rotational resistance exerted on the one-way clutch 175 from theshaft portion 174 in the reverse direction Q2 is reduced by a rolling bearing, for example. -
Fig. 8 is a diagram for explaining a rotatable angular range of thesub-intake cam 177. InFig. 8 , the one-way clutch 175 is not shown. As shown inFig. 8(a) and 8(b) , acutout 173a of theintake cam 173 is provided to extend in a circumferential direction. Similarly, theprojection piece 177a of thesub-intake cam 177 is provided to extend in the circumferential direction. A length of thecutout 173a in the circumferential direction is larger than a length of theprojection piece 177a in the circumferential direction. Theprojection piece 177a is arranged in thecutout 173a. - As shown in
Fig. 8(a) , one end TA1 of theprojection piece 177a abuts against one end TB1 of thecutout 173a, whereby the rotation of thesub-intake cam 177 in the reverse direction Q2 with respect to theshaft portion 174 is prevented. On the other hand, as shown inFig. 8(b) , the other end TA2 of theprojection piece 177a abuts against the other end TB2 of thecutout 173a, whereby the rotation of thesub-intake cam 177 in the forward direction Q1 with respect to theshaft portion 174 is prevented. Thus, a rotatable angular range of thesub-intake cam 177 with respect to theshaft portion 174 is restricted. Specifically, a difference of an angle between the one end TB1 and the other end TB2 of thecutout 173a in the circumferential direction from an angle between the one end TA1 and the other end TA2 of theprojection piece 177a in the circumferential direction is an angle by which thesub-intake cam 177 can rotate with respect to theshaft portion 174. - As shown in
Fig. 8(a) , with the one end TA1 of theprojection piece 177a abutting against the one end TB1 of thecutout 173a, anentire cam nose 177T of thesub-intake cam 177 overlaps with acam nose 173T of theintake cam 173 in the axis direction. Hereinafter, such a relative position of thesub-intake cam 177 with respect to theintake cam 173 is referred to as a normal position. On the other hand, as shown inFig. 8(b) , with the other end TA2 of theprojection piece 177a abutting against the other end TB2 of thecutout 173a, thecam nose 177T of thesub-intake cam 177 deviates from thecam nose 173T of theintake cam 173 by a constant angle in the circumferential direction, and at least a part of thecam nose 177T of thesub-intake cam 177 does not overlap with thecam nose 173T of theintake cam 173. Hereinafter, such a relative position of thesub-intake cam 177 with respect to theintake cam 173 is referred to as a start-up position. - The
sub-intake cam 177 does not act on the intake rocker arm RA1 (Fig. 7 ) at the normal position. On the other hand, thesub-intake cam 177 acts on the intake rocker arm RA1 at the start-up position. In this case, when the crank angle is in a range from the angle A21 to the angle A22 ofFig. 4 , the intake rocker arm RA1 is driven and the intake valve 15 (Fig. 7 ) is lifted. -
Figs. 9 and10 are diagrams for explaining the operations of theintake cam 173 and thesub-intake cam 177 in the reverse rotation start-up operation. In the present example, with the crank angle at the angle A20 ofFig. 4 , thesub-intake cam 177 is at the normal position as shown inFig. 9(a) . When the reverse rotation of thecrankshaft 13 is started, thecamshaft 170 rotates in the reverse direction Q2 as shown inFig. 9(b) . In this case, the rotational resistance (hereinafter referred to as the stationary system rotational resistance) generated by the friction member FR2 ofFig. 6 is exerted between the stationary system and the one-way clutch 175. As described above, the one-way clutch 175 is rotatable in the forward direction Q1 with respect to theshaft portion 174, so that the one-way clutch 175 rotates in the forward direction Q1 with respect to theshaft portion 174 by the stationary system rotational resistance. The rotational resistance (hereinafter referred to as the sub-cam rotational resistance) generated by the friction member FR1 ofFig. 6 is exerted between thesub-intake cam 177 and the one-way clutch 175. Therefore, thesub-intake cam 177 does not rotate with respect to the one-way clutch 175, and rotates in the forward direction Q1 together with the one-way clutch 175 with respect to theshaft portion 174. - In this manner, the reverse rotation of the
camshaft 170 is started, and then thesub-intake cam 177 does not rotate with respect to the stationary system or rotates in reverse with respect to the stationary system at a speed lower than that of thecamshaft 170. Thus, thesub-intake cam 177 rotates with a delay relative to theintake cam 173 and moves from the normal position to the start-up position. - During a period in which the crank angle is in a range from the angle A13 to the angle A12 of
Fig. 4 , theintake cam 173 pushes up the one end of the intake rocker arm RA1 as shown inFig. 9(c) . Thus, theintake valve 15 ofFig. 7 is lifted. Further, when thesub-intake cam 177 reaches the start-up position, the rotation of thesub-intake cam 177 with respect to theshaft portion 174 in the forward direction Q1 is prevented. Therefore, thesub-intake cam 177 rotates in the reverse direction Q2 together with theshaft portion 174. Further, the sub-cam rotational resistance is larger than the stationary system rotational resistance, so that the one-way clutch 175 rotates in the reverse direction Q2 together with thesub-intake cam 177 by the sub-cam rotational resistance. - During a period in which the crank angle is in a range from the angle A21 to the angle A22 of
Fig. 4 , thesub-intake cam 177 pushes up the one end of the intake rocker arm RA1 as shown inFig. 9(d) . Thus, theintake valve 15 ofFig. 7 is lifted. - While the
cam nose 177T abuts against the intake rocker arm RA1 with thesub-intake cam 177 at the start-up position in the present example, thecam nose 177T (Fig. 8 ) may abut against the intake rocker arm RA1 with thesub-intake cam 177 not reaching the start-up position. In this case, thesub-intake cam 177 is rotated in the forward direction Q1 with respect to theshaft portion 174 by a counterforce of the intake rocker arm RA1. Thus, thesub-intake cam 177 reaches the start-up position. Thesub-intake cam 177 does not push up the one end of the intake rocker arm RA1 until reaching the start-up position. When thesub-intake cam 177 reaches the start-up position, thesub-intake cam 177 pushes up the one end of the intake rocker arm RA1. Thus, similarly to the example ofFig. 9(d) , when the crank angle is in a range from the angle A21 to the angle A22, theintake valve 15 is lifted. - As shown in
Fig. 9(e) , when an abutment position between thesub-intake cam 177 and the intake rocker arm RA1 goes beyond the tip end of thecam nose 177T, the force in the reverse direction Q2 is applied from the intake rocker arm RA1 to thesub-intake cam 177. The tip end of thecam nose 177T refers to a portion in an outer peripheral surface of thecam nose 177T at which a distance from the axial center of theshaft portion 174 is maximum. Because the one-way clutch 175 is non-rotatable in the reverse direction Q2 with respect to theshaft portion 174, the one-way clutch 175 is not rotating in reverse with respect to theshaft portion 174. On the other hand, the force applied from the intake rocker arm RA1 to thesub-intake cam 177 is larger than the sub-cam rotational resistance, so that thesub-intake cam 177 rotates in the reverse direction Q2 with respect to the one-way clutch 175 while receiving the sub-cam rotational resistance as shown inFig. 9(f) . - In this manner, a speed of the reverse rotation of the
sub-intake cam 177 with respect to theshaft portion 174 decreases due to the sub-cam rotational resistance exerted between thesub-intake cam 177 and the one-way clutch 175. Therefore, thesub-intake cam 177 is prevented from instantaneously moving from the start-up position to the normal position. If thesub-intake cam 177 instantaneously moves from the start-up position to the normal position, theintake port 21 is instantaneously closed by theintake valve 15. Thus, theintake valve 15 collides with an edge of theintake port 21, and a contact noise is generated. Further, when the intake rocker arm RA1 also instantaneously moves, a contact noise caused by the movement of the intake rocker arm RA1 may be generated in thevalve driver 17. In the present example, thesub-intake cam 177 gently moves from the start-up position to the normal position, so that the generation of such a contact noise is prevented. - Thereafter, when the crank angle reaches the angle A31 of
Fig. 4 , a fuel-air mixture is ignited in thecombustion chamber 31a ofFig. 2 , and thecrankshaft 13 is driven in the forward direction. Thus, as shown inFig. 10(a) , thecamshaft 170 rotates in the forward direction Q1. The one-way clutch 175 is non-rotatable in the reverse direction Q2 with respect to theshaft portion 174, thereby rotating together with thecamshaft 170 in the forward direction Q1. Further, thesub-intake cam 177 rotates in the forward direction Q1 together with the one-way clutch 175 by the sub-cam rotational resistance. - As shown in
Fig. 10(b) , when thecam nose 177T of thesub-intake cam 177 abuts against the intake rocker arm RA1, the force in the reverse direction Q2 is applied from the intake rocker arm RA1 to thesub-intake cam 177. The one-way clutch 175 is non-rotatable in the reverse direction Q2 with respect to theshaft portion 174, thereby not rotating in reverse with respect to theshaft portion 174. On the other hand, because the force applied from the intake rocker arm RA1 to thesub-intake cam 177 is larger than the sub-cam rotational resistance, thesub-intake cam 177 does not push up the one end of the intake rocker arm RA1, and is rotated in the reverse direction Q2 with respect to the one-way clutch 175 by a counterforce of the intake rocker arm RA1. - Thus, as shown in
Fig. 10(c) , thesub-intake cam 177 moves to the normal position. Thereafter, during a period in which the crank angle is in a range from the angle A12 to the angle A13 ofFig. 3 , theintake cam 173 pushes up the one end of the intake rocker arm RA1, so that theintake valve 15 ofFig. 7 is lifted. Thereafter, with thesub-intake cam 177 held at the normal position, the forward rotation of thecamshaft 170 continues. Thus, during the normal operation, thesub-intake cam 177 does not drive the intake rocker arm RA1, and only theintake cam 173 drives the intake rocker arm RA1. - During the normal operation, when the rotation of the
crankshaft 13 and thecamshaft 170 is braked by a brake operation or the like, an inertial force in the forward direction Q1 is exerted on thesub-intake cam 177. Similarly to the example ofFig. 10(b) , if thesub-intake cam 177 moves from the normal position towards the start-up position by the inertial force, thesub-intake cam 177 is pushed back to the normal position by the counterforce of the intake rocker arm RA1. During the normal operation, in the case where thesub-intake cam 177 frequently moves in this manner, a contact noise generated by the intake rocker arm RA1 and thesub-intake cam 177, a contact noise generated by theprojection piece 177a and thecutout 173a ofFig. 8 and the like are frequently generated. - In the present example, the stationary system rotational resistance is exerted between the stationary system and the one-
way clutch 175, and the sub-cam rotational resistance is exerted between the one-way clutch 175 and thesub-intake cam 177. Thus, during the forward rotation of thecamshaft 170, thesub-intake cam 177 and the one-way clutch 175 are prevented from rotating in the forward direction Q1 with respect to thecamshaft 170. Therefore, during the normal operation, the generation of an abnormal noise caused by the movement of thesub-intake cam 177 is prevented. - In the
engine system 200 according to the present embodiment, thecrankshaft 13 rotates in reverse and then a fuel-air mixture is combusted, so that thecrankshaft 13 is driven in the forward direction. Thus, the startability of theengine 10 is enhanced. Further, during the reverse rotation of thecrankshaft 13, thesub-intake cam 177 rotates with a delay relative to theintake cam 173. Thus, it is possible to move thesub-intake cam 177 to the start-up position during the rotation of thecrankshaft 13 in the reverse direction without complicating the configuration of thevalve driver 17. Further, because thesub-intake cam 177 is not biased by a biasing member at the start-up position, thesub-intake cam 177 can be held at the normal position during the forward rotation of thecrankshaft 13. Thus, it is not necessary to move thesub-intake cam 177 from the start-up position to the normal position for each rotation of thecamshaft 170. Therefore, the generation of an abnormal noise such as a contact sound caused by the movement of thesub-intake cam 177 is prevented. - Further, in the present embodiment, the rotational resistance generated by the friction member FR2 is exerted between the stationary system and the one-
way clutch 175, so that thesub-intake cam 177 rotates with a delay relative to theintake cam 173. Thus, thesub-intake cam 177 can be stably moved to the start-up position using a simple configuration. -
Fig. 11 is a diagram for explaining the first modified example of thevalve driver 17. As for the example ofFig. 11 , differences fromFigs. 5 and6 will be described. Thevalve driver 17 ofFig. 11 includes afriction spring 180 instead of theholder 179 and the friction member FR2 ofFigs. 5 and6 . Thefriction spring 180 is a torsion spring and includes acoil 181 andarm portions coil 181 of thefriction spring 180 is fitted with the arm shaft SH2. - The
arm portion 182 abuts against an outer peripheral surface of thestorage 177b of thesub-intake cam 177. Thearm portion 183 is fixed to the cylinder head CH (Fig. 6 ). In this case, thearm portion 183 is pressed against thesub-intake cam 177 with a constant force. Thus, the rotational resistance is generated between the stationary system and thesub-intake cam 177. - Therefore, similarly to the case where the friction member FR2 of
Figs. 5 and6 is used, thesub-intake cam 177 rotates with a delay relative to theintake cam 173 during the reverse rotation of thecrankshaft 13. Thus, similarly to the example ofFigs. 5 and6 , thesub-intake cam 177 can be stably moved to the start-up position using a simple configuration. -
Fig. 12 is a diagram for explaining the second modified example of avalve driver 17. As for the example ofFig. 12 , differences fromFigs. 5 and6 will be described. Thevalve driver 17 ofFig. 12 includes a bar-shapedpressing member 185, acompression spring 186 and asupport member 187 instead of theholder 179 and the friction member FR2 ofFigs. 5 and6 . One end of the pressing member 85 is attached to a fixing portion HP via ashaft member 185a. The fixing portion HP is provided at the cylinder head CH (Fig. 6 ). The pressingmember 185 is held to be swingable with theshaft member 185a as a center. - One end of the
compression spring 186 is attached to thesupport member 187. Thesupport member 187 is fixed to the fixing portion HP. The other end of thecompression spring 186 abuts against the pressing member 85. The pressing member 85 is pressed against thesub-intake cam 177 by a biasing force of thecompression spring 186. Thus, the rotational resistance is generated between the stationary system and thesub-intake cam 177. - Therefore, similarly to the case where the friction member FR2 of
Figs. 5 and6 is used, thesub-intake cam 177 rotates with a delay relative to theintake cam 173 during the reverse rotation of thecrankshaft 13. Thus, similarly to the example ofFigs. 5 and6 , thesub-intake cam 177 can be stably moved to the start-up position using a simple configuration. -
Fig. 13 is a diagram for explaining the third modified example of avalve driver 17. As for the example ofFig. 13 , differences from the example ofFigs. 5 and6 will be described. Thevalve driver 17 ofFig. 13 includes an annular weight WT instead of theholder 179 and the friction member FR2 ofFigs. 5 and6 . The weight WT is provided at thesub-intake cam 177. In the present example, the weight WT is attached onto the outer peripheral surface of thestorage 177b. -
- In the formula (1), 'I' is the moment of inertia of the
sub-intake cam 177, and 'ω' is the angular acceleration of thecamshaft 170. Further, 'TF' is a drag torque of thesub-intake cam 177 with respect to theshaft portion 174 of thecamshaft 170. - The weight WT is provided, so that the moment of inertia of the
sub-intake cam 177 increases. The drag torque TF depends on the rotational resistance generated between the one-way clutch 175 and theshaft portion 174. As described above, the one-way clutch 175 is rotatable in the forward direction Q1 with respect to theshaft portion 174. Therefore, during the reverse rotation of thecamshaft 170, the drag torque TF is small. Thus, during the reverse rotation of thecamshaft 170, the above formula (1) is satisfied, and thesub-intake cam 177 rotates with a delay relative to thecamshaft 170. - In this manner, the moment of inertia of the
sub-intake cam 177 and the rotational resistance between theshaft portion 174 and the one-way clutch 175 are set such that thesub-intake cam 177 rotates with a delay relative to thecamshaft 170 by inertia. Thus, thesub-intake cam 177 can rotate with a delay while an increase in number of components is inhibited. A material (tungsten, for example) having a large specific gravity may be used as a material for thesub-intake cam 177, whereby the moment of inertia of thesub-intake cam 177 may be increased. - In the example of
Figs. 5 and6 , and the modified examples ofFigs. 11 to 13 , the one-way clutch 175 and the friction member FR1 are provided, so that thesub-intake cam 177 is prevented from instantaneously moving from the start-up position to the normal position by the reaction force from the intake rocker arm RA1. However, the present invention is not limited to this. -
Fig. 14 is a perspective view showing the appearance of avalve driver 17 for explaining the fourth modified example.Fig. 15 is a cutaway perspective view of thevalve driver 17 ofFig. 14 as viewed from a different position. As for the example ofFigs. 14 and15 , differences from the example ofFigs. 5 and6 will be described. - The
valve driver 17 ofFigs. 14 and15 includes asub-cam member 210, a holdingmember 220 and acentrifugal member 230 instead of the one-way clutch 175, thesub-intake cam 177 and the friction member FR1 ofFigs. 5 and6 . - The
sub-cam member 210 includes asub-intake cam 211, arotation plate 212 and aprojection piece 213. Thesub-intake cam 211 has a cam profile similar to that of thesub-intake cam 177 ofFigs. 5 and6 . Arotation plate 212 has a disc shape with the axial center of theshaft portion 174 of thecamshaft 170 as a center. Theprojection piece 213 is provided to project from a predetermined position in a peripheral edge of therotation plate 212 towards the side opposite to thesub-intake cam 211 in the axis direction. Thesub-cam member 210 is provided to be rotatable in a circumferential direction with respect to theshaft portion 174 of thecamshaft 170. - The
sub-cam member 210 is configured such that thesub-intake cam 211 rotates with a delay relative to theintake cam 173. For example, as shown in the example ofFigs. 5 and6 , the example ofFig. 11 or the example ofFig. 12 , a member that generates the rotational resistance between the stationary system and thesub-cam member 210 is provided, so that thesub-intake cam 211 rotates with a delay relative to theintake cam 173. Alternatively, as described in the example ofFig. 13 , the moment of inertia of thesub-cam member 210 is set to be large, whereby thesub-intake cam 211 rotates with a delay relative to theintake cam 173. - The holding
member 220 includes disc-shapedholding plates Fig. 15 ). The holdingmember 200 is fixed to theshaft portion 174 of thecamshaft 170. Each of the holdingplates rotation plate 212 of thesub-cam member 210. The holdingplates Fig. 15 ). Cutouts 221a, 222a extending in a circular arc shape in the circumferential direction are respectively formed at outer peripheries of the holdingplates cutouts cutouts positioner 220C. Theprojection piece 213 of thesub-cam member 210 is arranged in thepositioner 220C. As described below, a range of the rotation of thesub-cam member 210 with respect to thecamshaft 170 and the holdingmember 220 is restricted by theprojection piece 213 and thepositioner 220C. - In
Fig. 15 , thecutaway holding member 220 and thecutaway shaft portion 174 are shown. The hatching illustrates a cutaway sectional view. The holdingplate 222 of the holdingmember 220 is not shown inFig. 15 . Theshaft portion 174 is inserted into thecoupler 223 of the holdingmember 220. The holding pins 224, 225 extending in the axis direction are respectively provided to sandwich thecoupler 223 between the holdingplates - The
centrifugal member 230 is arranged between the holdingplates hole 230a is formed in thecentrifugal member 230. The holdingpin 224 of the holdingmember 220 is inserted into thehole 230a. Thus, thecentrifugal member 230 is held to be swingable with respect to the holdingmember 220 with the holdingpin 224 as a center. Anabutment portion 231 is provided at the end of thecentrifugal member 230 on one side of the holdingpin 224. Acutout 230b is formed at an outer periphery of thecentrifugal member 230 on the other side of the holdingpin 224. - A
projection 232 projecting in the axis direction is provided at an end of thecentrifugal member 230 on the other side of the holdingpin 224. One end and the other end of atension spring 240 are respectively engaged with the holdingpin 225 of the holdingmember 220 and theprojection 232 of thecentrifugal member 230. Thetension spring 240 biases thecentrifugal member 230 in a direction in which theprojection 232 comes closer to the holdingpin 225. As described below, a movement of a projection piece 213a of thesub-cam member 210 is restricted by thecentrifugal member 230. -
Fig. 16 is a diagram for explaining a range of the rotation of thesub-cam member 210. As shown inFig. 16(a) , theprojection piece 213 of thesub-cam member 210 abuts against one end TC1 of thepositioner 220C, so that the rotation of thesub-cam member 210 in the reverse direction Q2 with respect to thecamshaft 170 and the holdingmember 220 is prevented. In this case, as shown inFig. 16(b) , theentire cam nose 211T of thesub-intake cam 211 overlaps with thecam nose 173T of theintake cam 173 in the axis direction. That is, thesub-intake cam 211 is at the normal position. - On the other hand, as shown in
Fig. 16(c) , theprojection piece 213 of thesub-cam member 210 abuts against the other end TC2 of thepositioner 220C, so that the rotation of thesub-cam member 210 in the forward direction Q1 with respect to thecamshaft 170 and the holdingmember 220 is prevented. In this case, as shown inFig. 16(d) , thecam nose 211T of thesub-intake cam 211 and thecam nose 173T of theintake cam 173 deviate from each other by a constant angle in the circumferential direction. That is, thesub-intake cam 211 is at the start-up position. -
Fig. 17 is a diagram for explaining the swinging of thecentrifugal member 230. As shown inFig. 17(a) , in the case where a centrifugal force exerted on thecentrifugal member 230 is small, an inner periphery of thecentrifugal member 230 is maintained abutting against the outer peripheral surface of thecoupler 223 by a biasing force of the tension spring 240 (Fig. 15 ). In this case, a portion of thecentrifugal member 230 on the one side of the holdingpin 224 projects into thepositioner 220C, and a portion of thecentrifugal member 230 on the other side of the holdingpin 224 is stored between the holdingplates centrifugal member 220 is referred to as a low rotation position. In the case where the rotation speed of thecamshaft 170 is equal to or lower than a constant value, thecentrifugal member 230 is held at the low rotation position. - In the case where the
centrifugal member 230 is at the low rotation position, theabutment portion 231 is positioned in the vicinity of the other end TC2 in the positioner 230C. Therefore, when theprojection piece 213 is at the other end TC2 of thepositioner 220C, the movement of theprojection piece 213 is prevented by an abutment of theabutment portion 231 against theprojection piece 213. Thus, theprojection piece 213 is held at the other end TC2 of thepositioner 220C. Therefore, thesub-intake cam 211 is held at the start-up position ofFig. 16(d) . - On the other hand, as shown in
Fig. 17(b) , when a centrifugal force exerted on thecentrifugal member 230 is increased, thecentrifugal member 230 moves such that the inner periphery of thecentrifugal member 230 moves away from the outer peripheral surface of the coupler 233. In this case, a portion of thecentrifugal member 230 on the one side of the holdingpin 224 is stored between the holdingplates centrifugal member 230 on the other side of the holdingpin 224 projects into thepositioner 220C. Hereinafter, such a position of thecentrifugal member 230 is referred to as a high rotation position. In the case where the rotation speed of thecamshaft 170 is higher than the above-mentioned constant value, thecentrifugal member 230 is held at the high rotation position. - In the case where the
centrifugal member 230 is positioned at the high rotation position, acutout 230b is positioned in the vicinity of the one end TC1 of the positioner 230C. Therefore, in the case where being at the one end TC1 of thepositioner 220C, theprojection piece 213 is fitted with thecutout 230b. Thus, theprojection piece 213 is held at the one end TC1 of thepositioner 220C. Therefore, thesub-intake cam 211 is held at the normal position ofFig. 16(b) . -
Figs. 18 to 22 are diagrams for explaining the operations of theintake cam 173 and thesub-intake cam 211 in the reverse rotation start-up operation. InFigs. 18(a) ,19(a) ,20(a) ,21(a) and22(a) , the states of theintake cam 173, thesub-intake cam 211, the intake rocker arm RA1 and theintake valve 15 are shown. InFigs. 18(b) ,19(b) ,20(b) ,21(b) and22(b) , the states of theprojection piece 213 and thecentrifugal member 230 are shown. - At the start of the reverse rotation of the
crankshaft 13, thesub-intake cam 211 is at the normal position as shown inFig. 18(a) . Further, as shown inFig. 18(b) , thecentrifugal member 230 is at the low rotation position, and theprojection piece 213 is at the one end TC1 of thepositioner 220C. When the reverse rotation of thecrankshaft 13 is started, thecamshaft 170 rotates in the reverse direction Q2, and theintake cam 173 pushes up the one end of the intake rocker arm RA1 as shown inFig. 19(a) . Thus, theintake valve 15 is lifted. On the other hand, thesub-cam member 210 rotates with a delay relative to theintake cam 173. Thus, thesub-cam member 210 rotates in the forward direction Q1 with respect to theshaft portion 174, and thesub-intake cam 211 moves towards the start-up position. Further, as shown inFig. 19(b) , with thecentrifugal member 230 held at the low rotation position, theprojection piece 213 of thesub-cam member 210 moves from the one end TC1 towards the other end TC2 of thepositioner 220C. - Substantially, as shown in
Fig. 20(a) , when thecam nose 211T of thesub-intake cam 221 abuts against the intake rocker arm RA1, the force in the forward direction Q1 is exerted on thesub-intake cam 211 from the intake rocker arm RA1. Thus, thesub-intake cam 211 reaches the start-up position. Further, as shown inFig. 20(b) , theprojection piece 213 of thesub-cam member 210 reaches the other end TC2 of thepositioner 220C. In this case, theprojection piece 213 pushes down a portion of thecentrifugal member 230 on the one side of the holdingpin 224 and moves to the other end TC2 of thepositioner 220C by the force applied from the intake rocker arm RA1 to thesub-intake cam 211. - Subsequently, as shown in
Fig. 21(a) , when the abutment position of the intake rocker arm RA1 goes beyond the tip end of thecam nose 211T, the force in the reverse direction Q2 is applied from the intake rocker arm RA1 to thesub-intake cam 211. In this case, as shown inFig. 21(b) , theabutment portion 231 of thecentrifugal member 230 abuts against theprojection piece 213, so that theprojection piece 213 is prevented from moving towards the one end TC1 of thepositioner 220C. Therefore, thesub-cam member 210 does not rotate in the reverse direction Q2 with respect to thecamshaft 170, and thesub-intake cam 211 is held at the start-up position. Thus, the generation of a contact noise in theintake valve 15 and thevalve driver 17 is prevented. - Thereafter, a fuel-air mixture is combusted in the
combustion chamber 31a ofFig. 2 , and thecrankshaft 13 is driven in the forward direction. Thus, thecamshaft 170 rotates in the forward direction Q1. In this case, the rotation speeds of thecrankshaft 13 and thecamshaft 170 instantaneously increase. Therefore, thecentrifugal member 230 moves to the high rotation position, and theabutment portion 231 moves to a position inward of the holdingplates Fig. 14 . Therefore, theprojection 213 is movable towards the one end TC1 of thepositioner 220C. In this state, thecam nose 211T of thesub-intake cam 211 abuts against the intake rocker arm RA1 while thecamshaft 170 rotates in the forward direction Q1, and the force in the reverse direction Q2 is applied from the intake rocker arm RA1 to thesub-intake cam 211. - Thus, as shown in
Fig. 22(a) , thesub-cam member 210 rotates in the reverse direction Q2 with respect to thecamshaft 170, and thesub-intake cam 211 moves to the start-up position. Further, as shown inFig. 22(b) , theprojection piece 213 moves to the one end TC1 of thepositioner 220C. In this case, theprojection piece 213 pushes down a portion of thecentrifugal member 230 on the other side of the holdingpin 224 and moves to the one end TC1 of thepositioner 220C by the force in the reverse direction Q2 applied from the intake rocker arm RA1 to thesub-intake cam 211. At the one end TC1 of thepositioner 220C, theprojection piece 213 is fitted with thecutout 230b of thecentrifugal member 230. Thus, theprojection piece 213 is prevented from moving from the one end TC1 of thepositioner 220C. Therefore, thesub-cam member 210 is prevented from rotating in the forward direction Q1 with respect to thecamshaft 170, and thesub-intake cam 211 is held at the normal position. Thus, during the normal operation, the generation of an abnormal noise caused by the movement of thesub-cam member 210 is prevented. - In this manner, before the combustion of the fuel-air mixture and during the reverse rotation of the
crankshaft 13, thesub-intake cam 211 is held at the start-up position by thecentrifugal member 230. After the combustion of the fuel-air mixture and during the forward rotation of thecrankshaft 13, thesub-intake cam 211 is held at the normal position. Thus, any unnecessary movement of thesub-intake cam 211 is prevented using a simple configuration for utilizing a centrifugal force. Therefore, the generation of an abnormal noise caused by the movement of thesub-intake cam 211 is prevented. - While the
intake valve 15 and theexhaust valve 16 are driven by theintake cam 173, thesub-intake cams exhaust cam 172 via the intake rocker arm RA1 and the exhaust rocker arm RA2 in the above-mentioned embodiment, the present invention is not limited to this. Theengine 10 may be configured such that theintake cam 173 and thesub-intake cams intake valve 15, and may be configured such that theexhaust cam 172 directly drives theexhaust valve 16. - Further, in the above-mentioned embodiment, the
exhaust cam 172, theintake cam 173 and thesub-intake cams common camshaft 170. However, the present invention is not limited to this. A camshaft for theintake cam 173 and thesub-intake cams exhaust cam 172 may be separately provided. - Further, the above-mentioned embodiment is an example in which the present invention is applied to the motorcycle. However, the present invention is not limited to this. The present invention may be applied to another straddled vehicle such as a motor tricycle or an ATV (All Terrain Vehicle) or any another vehicle such as a four-wheeled automobile.
- In the following paragraphs, non-limiting examples of correspondences between various elements recited in the claims below and those described above with respect to various preferred embodiments of the present invention are explained.
- In the above-mentioned embodiments, the
engine system 200 is an example of an engine system, theengine 10 is an example of an engine, the rotaryelectrical machine 14 is an example of a rotation driver, thecrankshaft 13 is an example of a crankshaft, theECU 6 is an example of a controller and thevalve driver 17 is an example of a valve driver. Further, thecamshaft 170 is an example of a shaft portion, theintake cam 173 is an example of a first intake cam, thesub-intake cams friction spring 180 or thepressing member 185 is an example of a rotational resistance generation mechanism, the friction member FR2 is an example of a friction member, the one-way clutch 175 is an example of a one-way clutch, the friction member FR1 is an example of a resistance generation member, thecentrifugal member 230 is an example of a centrifugal member and the intake rocker arm RA1 is an example of a rocker arm. Further, themotorcycle 100 is an example of a vehicle, thebody 1 is an example of a main body, and therear wheel 7 is an example of a drive wheel. - As each of constituent elements are recited in the claims, various other elements having configurations or functions described in the claims can also be used.
- The present invention can be effectively utilized for various types of engine systems.
Claims (9)
- An engine system comprising:an engine;a rotation driver that rotates a crankshaft of the engine in a forward direction and a reverse direction; anda controller, whereinthe controller controls the engine and the rotation driver to rotate the crankshaft in the reverse direction and to cause a combustion of a fuel-air mixture in a combustion chamber of the engine such that the crankshaft is driven in the forward direction,the engine includes a valve driver that lifts an intake valve,the valve driver includesa shaft portion provided to rotate in the forward direction and the reverse direction in conjunction with a rotation of the crankshaft in the forward direction and the reverse direction, andfirst and second intake cams provided at the shaft portion,the first intake cam acts on the intake valve in a range of a crank angle corresponding to an intake process by integrally rotating with the shaft portion,the second intake cam is configured to be movable between a first position and a second position in a circumferential direction of the shaft portion by being rotatable within a constant angular range with respect to the shaft portion,the second intake cam overlaps with the first intake cam in an axis direction of the shaft portion when being at the first position, and acts on the intake valve within at least a part of a range of the crank angle corresponding to an exhaust stroke when being at the second position, andthe second intake cam, during the rotation of the crankshaft in the forward direction, is at the first position and does not act on the intake valve, and the second intake cam, during the rotation of the crankshaft in the reverse direction, moves to the second position by rotating with a delay relative to the first intake cam and acts on the intake valve.
- The engine system according to claim 1, wherein
the valve driver further includes
a stationary member, and
a rotational resistance generation mechanism that generates a rotational resistance between the stationary member and the second intake cam, and
during the rotation of the crankshaft in the reverse direction, the rotational resistance generated by the rotational resistance generation mechanism is larger than a rotational resistance between the shaft portion and the second intake cam. - The engine system according to claim 2, wherein
the rotational resistance generation mechanism includes a friction member that generates a friction between the stationary member and the second intake cam. - The engine system according to any one of claims 1 to 3, wherein
the moment of inertia of the second intake cam and the rotational resistance between the shaft portion and the second intake cam are set such that the second intake cam rotates with a delay relative to the first intake cam by inertia. - The engine system according to claim 4, wherein
the second intake cam is held at the shaft portion via a rolling bearing. - The engine system according to any one of claims 1 to 5, wherein
the valve driver further includes
a one-way clutch that does not transmit the rotation of the second intake cam in the forward rotation with respect to the shaft portion from the second intake cam to the shaft portion, and transmits the rotation of the second intake cam in the reverse direction with respect to the shaft portion from the second intake cam to the shaft portion, and
a resistance generation member that generates a rotational resistance between the one-way clutch and the shaft portion or between the one-way clutch and the second intake cam. - The engine system according to any one of claims 1 to 6, wherein
the valve driver further includes a centrifugal member, which is provided to rotate together with the shaft portion and is provided to be movable between a low speed position and a high speed position with respect to the shaft portion depending on a magnitude of a centrifugal force generated by the rotation of the shaft portion, and
the centrifugal member, before the combustion of the fuel-air mixture in the combustion chamber and during the rotation of the crankshaft in the reverse direction, holds the second intake cam at the second position while being at the low speed position, and after the combustion of the fuel-air mixture in the combustion chamber and during the rotation of the crankshaft in the forward direction, holds the second intake cam at the first position while being at the high speed position. - The engine system according to any one of claims 1 to 7, wherein
the valve driver further includes a rocker arm abutting against the first and second intake cams, and
the rocker arm, during the rotation of the crankshaft in the forward direction, acts on the second intake cam such that the second intake cam moves to the first position, and during the rotation of the crankshaft in the reverse direction, acts on the second intake cam such that the second intake cam moves to the second position. - A vehicle comprising;
a main body having a drive wheel; and
the engine system according to any one of claims 1 to 8 that generates a motive power for rotating the drive wheel.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2015120450 | 2015-06-15 | ||
PCT/JP2016/002057 WO2016203687A1 (en) | 2015-06-15 | 2016-04-15 | Engine system and vehicle |
Publications (2)
Publication Number | Publication Date |
---|---|
EP3309376A1 true EP3309376A1 (en) | 2018-04-18 |
EP3309376A4 EP3309376A4 (en) | 2018-07-04 |
Family
ID=57545799
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP16811168.0A Withdrawn EP3309376A4 (en) | 2015-06-15 | 2016-04-15 | Engine system and vehicle |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP3309376A4 (en) |
TW (1) | TWI589772B (en) |
WO (1) | WO2016203687A1 (en) |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS60190911U (en) * | 1984-05-28 | 1985-12-18 | 富士重工業株式会社 | engine decompression device |
JPS62195608U (en) * | 1986-06-03 | 1987-12-12 | ||
JPH0191007U (en) * | 1987-12-07 | 1989-06-15 | ||
JP2014077405A (en) * | 2012-10-11 | 2014-05-01 | Yamaha Motor Co Ltd | Engine system and saddle riding vehicle |
JP2015108322A (en) * | 2013-12-04 | 2015-06-11 | ヤマハ発動機株式会社 | Engine system and saddle-riding type vehicle |
-
2016
- 2016-04-15 WO PCT/JP2016/002057 patent/WO2016203687A1/en active Application Filing
- 2016-04-15 EP EP16811168.0A patent/EP3309376A4/en not_active Withdrawn
- 2016-04-21 TW TW105112488A patent/TWI589772B/en not_active IP Right Cessation
Also Published As
Publication number | Publication date |
---|---|
WO2016203687A1 (en) | 2016-12-22 |
TWI589772B (en) | 2017-07-01 |
EP3309376A4 (en) | 2018-07-04 |
TW201643311A (en) | 2016-12-16 |
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