JP2014077405A - Engine system and saddle riding vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine system capable of performing a stable starting-up of an engine and making a size of an engine small and provide a saddle riding vehicle having this engine.SOLUTION: An engine system 200 comprises a single cylinder engine 10 and an ECU 6. At the time of starting an engine 10, a crank shaft 13 is rotated in a reverse direction by a starter and generator 14. A valve driving part 17 drives an intake valve 15 in such a way that the fuel injected by an injector 19 is guided from an intake passage 22 into a combustion chamber 31a through an intake port 21 at a first time in the period in which the crank shaft 13 is rotated in an inverse direction. After this operation, the mixture gas is ignited by a spark plug 18 under a state in which the mixture gas is kept to be compressed within the combustion chamber 31a through the inverse rotation of the crank shaft 13 and at a second time in which a piston 11 does not reach to a compressed top dead center.

Description

  The present invention relates to an engine system and a saddle-ride type vehicle including the same.

  As a saddle-ride type vehicle such as a motorcycle equipped with a single-cylinder engine, there is one in which a generator having a starter motor function (hereinafter referred to as a starter / generator) is provided on a crankshaft. In such a vehicle, the torque is transmitted directly from the starter / generator to the crankshaft without going through the speed reducer. Therefore, the starter motor provided separately from the generator is used to drive the crank through the speed reducer. The torque transmitted to the crankshaft is significantly smaller than when torque is transmitted to the shaft.

  When the single-cylinder engine is stopped, the piston normally moves by inertia to a position just before reaching the compression top dead center where the pressure in the combustion chamber peaks. Therefore, when starting the engine, a large torque is required for the piston to exceed the first compression top dead center. However, as described above, when torque is directly transmitted from the starter / generator to the crankshaft, sufficient torque for starting the engine cannot be obtained, and the piston exceeds the first compression top dead center. May not be possible. Therefore, there is a technique for rotating the crankshaft in the reverse direction and then rotating it in the forward direction in order to improve the startability of the engine.

  In the engine start control device described in Patent Document 1, after stopping the engine, the crankshaft is reversely rotated to a predetermined position by a starter / generator provided on the crankshaft, and the crankshaft is moved to the position when the engine is started. Is rotated in the positive direction. In this case, the rotor position of the starter / generator is detected by the rotor sensor, and the rotational direction of the engine is determined based on the output signal of the rotor sensor. Based on the determination result, fuel injection and ignition are prohibited during reverse rotation of the engine.

JP 2005-248921 A

  However, even if the crankshaft is rotated in the forward direction after being rotated in the reverse direction, sufficient torque may not be obtained, and the piston may not be able to exceed the initial compression top dead center.

  In order to start the engine stably using the starter / generator as described above, a torque equivalent to the torque transmitted from the starter motor to the crankshaft via the reducer is generated by the starter / generator. Is required. For this purpose, it is necessary to use a high-performance starter / generator. However, such a starter / generator is larger than a generator provided separately from the starter motor. This increases the size of the engine. In addition, when a large starter / generator functions as a generator and the engine speed is particularly high, surplus power is likely to be generated, resulting in an increase in power generation loss.

  An object of the present invention is to provide an engine system capable of stably starting an engine and reducing the size of the engine, and a saddle-ride type vehicle including the same.

  (1) An engine system according to a first aspect of the present invention includes a single cylinder engine and a control unit configured to control the single cylinder engine, and the single cylinder engine includes a fuel injection device disposed in an intake passage; A valve drive unit configured to drive an intake valve that opens and closes an intake port and an exhaust valve that opens and closes an exhaust port, an ignition device configured to ignite an air-fuel mixture in a combustion chamber, and a crankshaft A starter / generator configured to rotate the crankshaft in the forward or reverse direction and generate electric power by rotating the crankshaft, and the controller reverses the crankshaft at the start The starting and power generating unit is controlled to rotate in the direction, and the valve driving unit is configured such that the fuel injected by the fuel injection device is a first point in time during which the crankshaft is rotated in the reverse direction. The intake valve is driven so as to be guided from the air passage through the intake port into the combustion chamber. After the fuel is guided into the combustion chamber at the first time point, the controller mixes in the combustion chamber by the reverse rotation of the crankshaft. The ignition device is controlled so that the air-fuel mixture is ignited at a second time when the air is compressed and the piston does not reach the compression top dead center.

  In this engine system, when the single cylinder engine is started, the crankshaft is rotated in the reverse direction by the starter / power generation unit. The intake valve is driven by the valve drive unit so that the fuel injected by the fuel injection device is guided from the intake passage through the intake port into the combustion chamber at a first time point during which the crankshaft is rotated in the reverse direction. After the fuel is introduced into the combustion chamber at the first time point, at a second time point when the air-fuel mixture is compressed in the combustion chamber due to the reverse rotation of the crankshaft and the piston does not reach the compression top dead center. The mixture is ignited by the ignition device.

  In this case, the piston is driven by the energy of the explosion generated in the combustion chamber so that the crankshaft rotates in the positive direction. Thereby, sufficient torque in the positive direction can be obtained, and the piston can easily exceed the compression top dead center. Therefore, the engine can be started stably. In addition, since a sufficient torque for starting the engine can be obtained by ignition of the air-fuel mixture without using a large starter / power generator, the engine can be downsized. On the other hand, even for an engine with a large displacement that is more difficult to exceed the first compression top dead center, torque is applied directly to the crankshaft rather than a starter motor that transmits torque to the crankshaft via a speed reducer. It is possible to use a starting and activating part for transmission. Furthermore, since it is not necessary to use a large starter / power generator, it is possible to suppress the generation of excess power.

  (2) The first time point may be included in a period during which the piston descends from the exhaust top dead center when the crankshaft rotates in the reverse direction.

  In this case, fuel and air can be reliably introduced into the combustion chamber when the crankshaft rotates in the reverse direction.

  (3) The valve drive unit drives the exhaust valve so that the exhaust port is opened during a period in which the rotation angle of the crankshaft is in the first range when the crankshaft rotates in the positive direction, and the rotation angle of the crankshaft When the intake valve is driven so that the intake port is opened during a period in which the crankshaft is in the second range, the rotation angle of the crankshaft is in a third range within the first range when the crankshaft rotates in the reverse direction The intake valve may be driven so that the intake port is opened, and the third range may be larger than the portion of the second range in the first range.

  The direction of movement of the piston is reversed between when the crankshaft is rotated in the forward direction and when it is rotated in the reverse direction. Therefore, in the angle range where exhaust is to be performed when the crankshaft rotates in the forward direction, intake is performed when the crankshaft rotates in the reverse direction. Therefore, by setting the third range to be larger than the second range portion in the first range, intake is sufficiently performed when the crankshaft rotates in the reverse direction. Thereby, fuel and air can be sufficiently introduced into the combustion chamber. As a result, an explosion can be appropriately generated in the combustion chamber.

  (4) There may be an interval between the second range and the third range. In this case, fuel and air can be introduced into the combustion chamber at an appropriate timing.

  (5) The valve drive unit may drive the exhaust valve so that the exhaust port is not opened during a period in which the rotation angle of the crankshaft is at least in the third range when the crankshaft rotates in the reverse direction.

  In this case, when the crankshaft rotates in the reverse direction, the intake port is opened and the exhaust port is closed in the third range, so that fuel and air can be efficiently introduced into the combustion chamber.

  (6) When the crankshaft rotates in the forward direction, the control unit injects fuel when the crankshaft rotation angle is in the fourth range, and when the crankshaft rotates in the reverse direction, You may control a fuel-injection apparatus so that a fuel may be injected when it exists in the 5th range different from a 4th range.

  In this case, fuel can be injected at an appropriate timing each time the crankshaft rotates in the forward direction and in the reverse direction. Thereby, fuel can be appropriately guided into the combustion chamber.

  (7) The fifth range may be set so as to be positioned more advanced than the fourth range when the crankshaft rotates in the reverse direction.

  In this case, fuel can be injected at an appropriate timing when the crankshaft rotates in the reverse direction. Thereby, fuel can be appropriately guided into the combustion chamber.

  (8) The fifth range may be within the second range. In this case, when the crankshaft rotates in the reverse direction, fuel can be injected before the intake port is opened. Thereby, fuel can be sufficiently introduced into the combustion chamber during intake.

  (9) The valve drive unit is configured to rotate integrally with the shaft unit provided to rotate in conjunction with the rotation of the crankshaft, and is configured to act on the intake valve. A first intake cam, a second intake cam that is rotatably provided with respect to the shaft portion and configured to act on the intake valve, and a movement of the second intake cam with respect to the shaft portion is limited. A first restricting mechanism configured and a first biasing member configured to bias the second intake cam, wherein the first limiting mechanism includes a second direction in the first direction. Provided to stop the rotation of the intake cam at the first position of the shaft and to stop the rotation of the second intake cam in the second direction opposite to the first direction at the second position of the shaft The second intake cam acts on the intake valve in the first position and does not act on the intake valve in the second position. The first urging member is configured to urge the second intake cam in the first direction. When the crankshaft rotates in the positive direction, the first urging member moves from the intake valve to the second intake cam. When a reaction force larger than the urging force of the urging member is applied, the second intake cam is moved in the second direction, and the second intake cam acts on the intake valve when the crankshaft rotates in the reverse direction. In this way, the intake cam may be moved to the first position by the urging force of the first urging member.

  In this case, when the crankshaft rotates in the positive direction, only the first intake cam acts on the intake valve, and the second intake cam does not act on the intake valve by being moved in the second direction. On the other hand, when the crankshaft rotates in the reverse direction, the first intake cam acts on the intake valve, and the second intake cam moves to the first position to act on the intake valve. As a result, the intake port can be opened when the crankshaft rotates in the reverse direction within an angular range in which exhaust should be performed when the crankshaft rotates in the forward direction. Thereby, the fuel can be sufficiently introduced into the combustion chamber.

  (10) When the first intake cam has a first cam nose, the second intake cam has a second cam nose, and the second intake cam is in the second position, the second cam nose When the whole overlaps with the first cam nose and the second intake cam is in the first position, at least a part of the second cam nose may not overlap with the first cam nose.

  In this case, it is possible to switch between a state where the second intake cam acts on the intake valve and a state where it does not act with a simple configuration.

  (11) The valve drive unit is provided so as to be rotatable with respect to the shaft portion, and is configured to rotate the exhaust cam with respect to the shaft portion at a predetermined position of the shaft portion. A stop portion provided to be movable between a rotation stop position for stopping and a rotatable position allowing the exhaust cam to rotate relative to the shaft portion, and the stop portion to the rotation stop position when the crankshaft rotates in the forward direction. It may further include a moving part that moves and moves the stop part to a rotatable position when the crankshaft rotates in the reverse direction.

  In this case, when the crankshaft rotates in the positive direction, the stop portion is moved to the rotation stop position by the moving portion, so that the exhaust cam is fixed at a predetermined position of the shaft portion. Thereby, the exhaust cam acts on the exhaust valve. On the other hand, when the crankshaft rotates in the reverse direction, the stop portion is moved to the rotatable position by the moving portion, so that the exhaust cam can rotate with respect to the shaft portion. As a result, the exhaust cam does not act on the exhaust valve at least in a certain angular range. Therefore, the exhaust port can be appropriately opened when the crankshaft rotates in the forward direction, and the exhaust port can be kept closed when the crankshaft rotates in the reverse direction. As a result, intake can be performed efficiently when the crankshaft rotates in the reverse direction.

  (12) The valve drive unit further includes a second limiting mechanism configured to limit the movement of the exhaust cam with respect to the shaft portion, and the second limiting mechanism causes the exhaust cam to rotate in the first direction. The exhaust cam is provided to stop at the third position of the shaft portion and to stop the rotation of the exhaust cam in the second direction at the fourth position of the shaft portion. When the reaction force is applied to the cam, the exhaust cam is moved in the first direction, and the stop portion may stop the exhaust cam at the fourth position at the rotation stop position.

  In this case, when the crankshaft rotates in the positive direction, the exhaust cam is stopped at the fourth position by the second limiting mechanism. In this state, the exhaust cam is fixed to the shaft portion by the stop portion. On the other hand, when the crankshaft rotates in the reverse direction, the exhaust cam is rotated in the first direction by the reaction force from the exhaust valve. Therefore, it is possible to switch between a state where the second intake cam acts on the intake valve and a state where it does not act on the intake valve within a certain angle range with a simple configuration.

  (13) The valve drive unit further includes a second urging member configured to urge the exhaust cam in the second direction, and the urging force of the second urging member is reverse to the crankshaft. The reaction force in the first direction applied from the exhaust valve to the exhaust cam during rotation may be smaller.

  In this case, when the crankshaft rotates in the reverse direction, the urging force in the second direction by the second urging member is smaller than the reaction force in the first direction from the exhaust valve. Is prevented from acting on the exhaust valve. On the other hand, when the crankshaft rotates in the positive direction, the exhaust cam is biased in the second direction, so that the exhaust cam is reliably moved to the fourth position.

  (14) The control unit may ignite the air-fuel mixture by the ignition device with the crankshaft rotating in the positive direction at the second time point. In this case, the crankshaft can be reliably rotated in the positive direction after the second time point.

  (15) The control unit may drive the crankshaft in the forward direction by the starter / power generation unit after the second time point. In this case, a greater torque in the positive direction is obtained after the second time point. Thereby, the piston can easily exceed the compression top dead center.

  (16) A saddle-ride type vehicle according to a second aspect of the invention includes a main body having driving wheels and the engine system according to the first aspect of the invention that generates power for rotating the driving wheels. .

  In this saddle-ride type vehicle, the drive wheels are rotated by the power generated by the engine system. Thereby, the main body moves. In this case, since the engine system according to the first invention is used, the engine can be started stably and the engine can be downsized.

  ADVANTAGE OF THE INVENTION According to this invention, an engine can be started stably and the enlargement of an engine can be suppressed.

1 is a schematic side view showing a schematic configuration of a motorcycle according to an embodiment of the present invention. It is a schematic diagram for demonstrating the structure of an engine system. It is a figure for demonstrating operation | movement of an engine. It is a figure for demonstrating operation | movement of an engine. It is a flowchart of the 1st example of an engine starting process. It is a flowchart of the 1st example of an engine starting process. It is a flowchart of the 1st example of an engine starting process. It is a flowchart of the 2nd example of an engine starting process. It is a typical side view for demonstrating the specific example of a valve drive part. It is sectional drawing of a valve drive part and its peripheral part. It is an external perspective view of the valve drive unit It is sectional drawing of a valve drive part. It is a partial exploded perspective view of a valve drive part. It is a partial exploded perspective view of a valve drive part. It is an external appearance perspective view of a switching mechanism. It is sectional drawing of a switching mechanism. It is a disassembled perspective view of a press mechanism. It is a figure for demonstrating a main intake cam and a sub intake cam. It is a figure for demonstrating the effect | action of the main intake cam and the sub intake cam at the time of forward rotation of a crankshaft. It is a figure for demonstrating the effect | action of the main intake cam and the sub intake cam at the time of reverse rotation of a crankshaft. It is a figure showing the lift amount of an intake valve. It is sectional drawing for demonstrating an exhaust cam It is a figure for demonstrating the effect | action of the exhaust cam at the time of forward rotation of a crankshaft. It is a figure for demonstrating the effect | action of the exhaust cam at the time of reverse rotation of a crankshaft. It is a figure which shows operation | movement of the exhaust cam immediately after the rotation direction of a crankshaft switches from the reverse direction to the forward direction. It is a figure for demonstrating operation | movement of a switching mechanism. It is a figure for demonstrating the other example of the switching mechanism.

  Hereinafter, a motorcycle will be described as an example of a saddle-ride type vehicle according to an embodiment of the present invention with reference to the drawings.

(1) Motorcycle FIG. 1 is a schematic side view showing a schematic configuration of a motorcycle according to an embodiment of the present invention. In the motorcycle 100 of FIG. 1, a front fork 2 is provided at the front portion of the vehicle body 1 so as to be swingable in the left-right direction. A handle 4 is attached to the upper end of the front fork 2, and a front wheel 3 is rotatably attached to the lower end of the front fork 2.

  A seat 5 is provided at a substantially upper center portion of the vehicle body 1. An ECU (Engine Control Unit) 6 is disposed at the lower rear of the seat 5, and a single cylinder engine 10 is provided below the seat 5. The engine system 200 is configured by the ECU 6 and the engine 10. A rear wheel 7 is rotatably attached to the lower rear end of the vehicle body 1. The rear wheel 7 is rotationally driven by the power generated by the engine 10.

(2) Engine System FIG. 2 is a schematic diagram for explaining the configuration of the engine system 200. As shown in FIG. 2, the engine 10 includes a piston 11, a connecting rod 12, a crankshaft 13, a starter / generator 14, an intake valve 15, an exhaust valve 16, a valve drive unit 17, a spark plug 18, and an injector 19.

  The piston 11 is provided so as to be able to reciprocate in the cylinder 31 and is connected to the crankshaft 13 via a connecting rod 12. The reciprocating motion of the piston 11 is converted into the rotational motion of the crankshaft 13. A starter / generator 14 is provided on the crankshaft 13. The starter / generator 14 is a generator having a function of a starter motor, and rotates the crankshaft 13 in the forward direction and the reverse direction and generates electric power by the rotation of the crankshaft 13. The starter / generator 14 directly transmits torque to the crankshaft 13 without using a reduction gear. A one-way clutch (not shown) is provided between the crankshaft 13 and the rear wheel 7. The forward rotation of the crankshaft 13 (hereinafter referred to as forward rotation) is transmitted to the rear wheel 7 via the one-way clutch, and the reverse rotation of the crankshaft 13 (hereinafter referred to as reverse rotation) is transmitted to the rear wheel 7. Not transmitted.

  A combustion chamber 31 a is formed on the piston 11. The combustion chamber 31 a communicates with the intake passage 22 through the intake port 21 and communicates with the exhaust passage 24 through the 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 a valve drive unit 17. The intake passage 22 is provided with a throttle valve SL for adjusting the flow rate of air flowing from the outside. The spark plug 18 is configured to ignite the air-fuel mixture in the combustion chamber 31a. The injector 19 is configured to inject fuel into the intake passage 22.

  The ECU 6 includes, for example, a CPU (Central Processing Unit) and a memory. A microcomputer may be used instead of the CPU and the memory. A starter switch 41, an intake pressure sensor 42, a crank angle sensor 43 and a current sensor 44 are electrically connected to the ECU 6. The starter switch 41 is provided, for example, on the handle 4 in FIG. 1 and is operated by the driver. The intake pressure sensor 42 detects the pressure in the intake passage 22. The crank angle sensor 43 detects the rotation angle of the crankshaft 13. The current sensor 44 detects a current (hereinafter referred to as a motor current) flowing through the starter / generator 14.

  The operation of the starter switch 41 is given to the ECU 6 as an operation signal, and the detection results by the intake pressure sensor 42, the crank angle sensor 43 and the current sensor 44 are given to the ECU 6 as detection signals. The ECU 6 controls the starter / generator 14, the spark plug 18, and the injector 19 based on the given operation signal and detection signal.

(3) Engine Operation FIGS. 3 and 4 are diagrams for explaining the operation of the engine 10. FIG. 3 shows the operation of the engine 10 during normal operation, and FIG. 4 shows the operation of the engine 10 during startup. Here, the normal operation refers to a state in which the engine 10 operates stably after the engine 10 is started.

  3 and 4, the rotation angle in the range of two rotations (720 degrees) of the crankshaft 13 is represented by one circle. Two rotations of the crankshaft 13 correspond to one cycle of the engine 10. One cycle of the engine 10 includes an intake process, a compression process, a combustion stroke, and an exhaust process. Hereinafter, the rotation angle of the crankshaft 13 is referred to as a crank angle.

  The crank angle sensor 43 in FIG. 2 detects a rotation angle in the range of one rotation (360 degrees) of the crankshaft 13. The ECU 6 determines whether the crank angle detected by the crank angle sensor 43 based on the pressure in the intake passage 22 detected by the intake pressure sensor 42 is one of the two rotations of the crankshaft 13 corresponding to one cycle of the engine 10. It is determined whether it corresponds to the rotation of. Thereby, the ECU 6 can acquire the rotation angle in the range of two rotations (720 degrees) of the crankshaft 13.

  3 and 4, the angle A0 is a crank angle when the piston 11 (FIG. 2) is located at the exhaust top dead center, and the angle A2 is a crank angle when the piston 11 is located at the compression top dead center. The angles A1 and A3 are crank angles when the piston 11 is located at the bottom dead center. Arrow R1 represents the direction of change of the crank angle when the crankshaft 13 is rotated forward, and arrow R2 represents the direction of change of the crank angle when the crankshaft 13 is rotated reversely. Arrows P1 to P4 represent the moving direction of the piston 11 when the crankshaft 13 rotates forward, and the arrows P5 to P8 represent the moving direction of the piston 11 when the crankshaft 13 rotates reversely.

(3-1) Normal Operation First, the operation of the engine 10 during normal operation will be described with reference to FIG. During normal operation, the crankshaft 13 (FIG. 2) rotates in the positive direction. Therefore, the crank angle changes in the direction of arrow R1. In this case, as indicated by arrows P1 to P4, the piston 11 (FIG. 2) descends in the range from the angle A0 to the angle A1, the piston 11 rises in the range from the angle A1 to the angle A2, and from the angle A2 The piston 11 descends in the range up to the angle A3, and the piston 11 rises in the range from the angle A3 to the angle A0.

  At an angle A11, fuel is injected into the intake passage 22 (FIG. 2) by the injector 19 (FIG. 2). In the positive direction, the angle A11 is located on the more advanced side than the angle A0. The angle A11 is an example of the fourth range. Subsequently, in the range from the angle A12 to the angle A13, the intake port 21 (FIG. 2) is opened by the intake valve 15 (FIG. 2). In the positive direction, the angle A12 is positioned more retarded than the angle A11 and more advanced than the angle A0, and the angle A13 is positioned more retarded than the angle A1. A range from the angle A12 to the angle A13 is an example of the second range. Thereby, the air-fuel mixture containing air and fuel is introduced into the combustion chamber 31a (FIG. 2) through the intake port 21.

  Next, at the angle A14, the air-fuel mixture in the combustion chamber 31a (FIG. 2) is ignited by the spark plug 18 (FIG. 2). The angle A14 substantially coincides with the angle A2. Thereby, an explosion occurs in the combustion chamber 31a. The energy of the explosion becomes the driving force for the piston 11. Thereafter, the exhaust port 23 (FIG. 2) is opened by the exhaust valve 16 (FIG. 2) in the range from the angle A15 to the angle A16. In the positive direction, the angle A15 is located on the more advanced side than the angle A3, and the angle A16 is located on the more retarded side than the angle A0. The range from the angle A15 to the angle A16 is an example of the first range. Thereby, the gas after combustion is discharged | emitted through the exhaust port 23 from the combustion chamber 31a.

(3-2) At Start Next, the operation of the engine 10 at the start will be described with reference to FIG. In FIG. 4, first, the crankshaft 13 (FIG. 2) is rotated in the forward direction or the reverse direction, so that the crank angle is adjusted to the angle A30. The angle A30 is located between the angle A1 and the angle A2. Subsequently, the crankshaft 13 is rotated in the reverse direction from the angle A30.

  When the crankshaft 13 rotates in the reverse direction, the crank angle changes in the direction of the arrow R2. In this case, as indicated by arrows P5 to P8, the piston 11 is lowered in the range from the angle A2 to the angle A1, the piston 11 is raised in the range from the angle A1 to the angle A0, and from the angle A0 to the angle A3. The piston 11 descends in the range, and the piston 11 rises in the range from the angle A3 to the angle A2. The moving direction of the piston 11 when the crankshaft 13 rotates in the reverse direction is opposite to the moving direction of the piston 11 when the crankshaft 13 rotates in the forward direction.

  At an angle A23, fuel is injected into the intake passage 22 (FIG. 2) by the injector 19 (FIG. 2). In the reverse direction, the angle A23 is located on the more advanced side than the angle A0. The angle A23 is an example of the fifth range. Further, in the range from the angle A13 to the angle A12 and the range from the angle A21 to the angle A22, the intake port 21 (FIG. 2) is opened by the intake valve 15 (FIG. 2). In the reverse direction, the angles A21 and A22 are located on the more retarded side than the angle A0. In this case, since the piston 11 rises in the range from the angle A1 to the angle A0, air and fuel are hardly introduced into the combustion chamber 31a in the range from the angle A13 to the angle A12. Thereafter, since the piston 11 descends in the range from the angle A0 to the angle A3, the air-fuel mixture containing air and fuel is introduced into the combustion chamber 31a through the intake port 21 in the range from the angle A21 to the angle A22. A temporary point where the crank angle is in the range from the angle A21 to the angle A22 is an example of the first time point. The range from the angle A16 to the angle A12 and the range from the angle A21 to the angle A22 are examples of the third range.

  Subsequently, at the angle A31, the rotation direction of the crankshaft 13 is switched from the reverse direction to the forward direction. In the reverse direction, the angle A31 is located slightly on the advance side with respect to the angle A2. As a result, the crank angle changes in the direction of arrow R1. At the angle A31, the air-fuel mixture in the combustion chamber 31a is ignited by the spark plug 18 (FIG. 2). Thereby, an explosion occurs in the combustion chamber 31a, and the crankshaft 13 is driven. The time point when the crank angle is the angle A31 is an example of the second time point.

  In the present embodiment, after the reverse rotation of the crankshaft 13 is stopped, the air-fuel mixture in the combustion chamber 31a is ignited by the spark plug 18. Thereby, the crankshaft 13 can be reliably driven in the forward direction. If it is possible to drive the crankshaft 13 in the forward direction by adjusting the ignition timing, etc., the air-fuel mixture in the combustion chamber 31a is stopped by the spark plug 18 before the reverse rotation of the crankshaft 13 is stopped. May be ignited.

  Thereafter, the same operation as in FIG. 3 is performed. Specifically, fuel is injected into the intake passage 22 (FIG. 2) at the angle A11 in FIG. 3, and the air-fuel mixture is introduced into the combustion chamber 31a in the range from the angle A12 to the angle A13. Subsequently, at the angle A14, the air-fuel mixture in the combustion chamber 31a is ignited by the spark plug 18 (FIG. 2), and the burned gas is discharged from the combustion chamber 31a through the exhaust port 23 in the range from the angle A15 to the angle A16. Is done. Thereafter, the engine 10 shifts to normal operation.

  As described above, in the present embodiment, when the engine 10 is started, the air-fuel mixture is guided to the combustion chamber 31a while the crankshaft 13 is reversely rotated by the starter / generator 14, and then the piston 11 is brought to the compression top dead center. In the approached state, the air-fuel mixture in the combustion chamber 31a is ignited. Thereby, the piston 11 is driven so that the crankshaft 13 rotates in the forward direction, and sufficient torque in the forward direction is obtained. As a result, the piston 11 can easily exceed the first compression top dead center.

  In addition, after the rotation direction of the crankshaft 13 is switched from the reverse direction to the forward direction at the angle A31, before the intake port 21 is opened by the intake valve 15 in the range from the angle A12 to the angle A13 in FIG. The exhaust port 23 may be opened by the exhaust valve 16 in the range from the angle A15 to the angle A16. In this case, before the intake is performed in the range from the angle A12 to the angle A13, the gas after combustion by ignition at the angle A31 is discharged from the combustion chamber 31a.

(4) Engine start process (4-1) First example When the engine 10 is started, the ECU 6 performs an engine start process based on a control program stored in advance in a memory. 5 to 7 are flowcharts of a first example of the engine start process. The engine start process is started, for example, when a main switch (not shown) is turned on.

  As shown in FIG. 5, first, the ECU 6 determines whether or not the current crank angle is stored in the memory (step S1). The current crank angle is stored in the memory, for example, when the engine 10 was stopped last time. When the current crank angle is stored, the ECU 6 controls the starter / generator 14 so that the current crank angle matches the angle A30 in FIG. 4 (step S2).

  If the current crank angle is not stored, the ECU 6 controls the starter / generator 14 so that the crankshaft 13 rotates in the forward direction (step S3). In this case, the torque of the starter / generator 14 is adjusted based on the detection signal from the current sensor 44 (FIG. 2) so that the piston 11 does not exceed the compression top dead center (angle A2 in FIGS. 3 and 4). Is done.

  Next, the ECU 6 determines whether or not a specified time has elapsed since the rotation of the crankshaft 13 was started in step S3 (step S4). When the specified time has not elapsed, the ECU 6 controls the starter / generator 14 so that the rotation of the crankshaft 13 in the positive direction is continued. When the specified time has elapsed, the ECU 6 controls the starter / generator 14 so that the rotation of the crankshaft 13 is stopped (step S5). As a result, the crank angle is adjusted close to the angle A30 in FIG.

  In step S3, the crank angle may be detected when the crankshaft 13 is rotated in the forward direction, and the crank angle may be adjusted to the angle A30 in FIG. 4 based on the detected value.

  Subsequently, as shown in FIG. 6, the ECU 6 determines whether or not a predetermined starting condition for the engine 10 is satisfied (step S6). The starting condition of the engine 10 is, for example, that the starter switch 41 (FIG. 2) is turned on. As a starting condition of the engine 10, other conditions such as a brake switch (not shown) being turned off, an accelerator grip (not shown) being operated, or a battery voltage (not shown) being lowered may be set.

  When the start condition of the engine 10 is satisfied, the ECU 6 performs a timeout setting for the engine start process (step S7). Specifically, the elapsed time is measured from that point. When the elapsed time reaches a predetermined end time, the engine start process is forcibly ended (step S17 described later).

  Next, the ECU 6 controls the starter / generator 14 so that the crankshaft 6 is rotated in the reverse direction (step S8). Next, the ECU 6 determines whether or not the current crank angle has reached the angle A23 in FIG. 4 based on detection signals from the intake pressure sensor 42 (FIG. 2) and the crank angle sensor 43 (FIG. 2). (Step S9). The ECU 6 repeats the process of step S9 until the current crank angle reaches the angle A23. When the current crank angle reaches the angle A23, the ECU 6 controls the injector 19 so that fuel injection into the intake passage 22 (FIG. 2) is started (step S10).

  Next, the ECU 6 determines whether or not a predetermined injection time has elapsed since the start of fuel injection in step S10 (step S11). The ECU 6 controls the injector 19 so that fuel injection is continued until a predetermined injection time has elapsed. When the predetermined injection time has elapsed, the ECU 6 controls the injector 19 so that the fuel injection is stopped (step S12).

  Next, as shown in FIG. 7, the ECU 6 determines whether or not the motor current has reached a predetermined threshold value based on the detection signal from the current sensor 44 (step S13). In this case, the motor current increases as the crank angle approaches the angle A2 in FIG. In this example, when the crank angle reaches the angle A31 in FIG. 4, the motor current reaches the threshold value.

  When the current flowing through the starter / generator 14 reaches a predetermined threshold value, the ECU 6 controls the starter / generator 14 so that the reverse rotation of the crankshaft 13 is stopped (step S14). Then, energization of the spark plug 18 is started (step S15). Next, the ECU 6 determines whether or not a predetermined energization time has elapsed since the start of energization in step S15 (step S16). The ECU 6 continues energization to the spark plug 18 until a predetermined energization time elapses. When a predetermined energization time has elapsed, the ECU 6 stops energizing the spark plug 18 (step S17). Thereby, the air-fuel mixture in the combustion chamber 31a is ignited. Further, the ECU 6 controls the starter / generator 14 so that the crankshaft 13 rotates in the forward direction (step S18). Thereby, ECU6 complete | finishes an engine starting process. Thereafter, the ECU 6 performs a control operation corresponding to the normal operation of FIG. Note that the driving of the crankshaft 13 by the starter / generator 14 is stopped after a predetermined time elapses from the process of step S18, for example.

  If the motor current has not reached the threshold value in step S13, the ECU 6 determines whether or not a predetermined end time has elapsed from the timeout setting in step S7 of FIG. 6 (step S19). Due to an abnormality in the engine 10, the current flowing through the starter / generator 14 may not reach the threshold value, and a predetermined end time may elapse from the timeout setting. The abnormality of the engine 10 includes malfunction of the starter / generator 14 or malfunction of the valve drive unit 17. If the end time has not elapsed, the ECU 6 returns to the process of step S13. When the end time has elapsed, the ECU 6 controls the starter / generator 14 so that the reverse rotation of the crankshaft 13 is stopped (step S20), and warns the driver that an abnormality has occurred in the engine 10. (Step S21). Specifically, for example, a warning lamp (not shown) is turned on. Thereby, ECU6 complete | finishes an engine starting process.

(4-2) Second Example FIG. 8 is a flowchart of a second example of the engine start process. The ECU 6 may perform steps S31 to S41 in FIG. 8 instead of steps S13 to S21 in FIG.

  In the example of FIG. 8, the ECU 6 determines the crankshaft 13 in advance after the reverse rotation of the crankshaft 13 is started in step S8 of FIG. 6 based on the detection signal from the crank angle sensor 43 (FIG. 2). It is determined whether or not the reverse rotation angle has been rotated (step S31). The reverse rotation angle corresponds to an angle from angle A30 to angle A31 in FIG. For example, after a reverse rotation of the crankshaft 13 is started, when a predetermined number of pulses corresponding to the reverse rotation angle is given as a detection signal from the crank angle sensor 43, the ECU 6 determines that the crankshaft 13 has rotated the reverse rotation angle. judge.

  When the crankshaft 13 rotates at the reverse rotation angle, the ECU 6 controls the starter / generator 14 so that the reverse rotation of the crankshaft 13 is stopped (step S32), and starts energizing the spark plug 18. (Step S33).

  Next, the ECU 6 determines whether or not the crankshaft 13 has rotated a predetermined energization angle after energization is started in step S33 (step S34). The energization angle corresponds to the angle at which the crankshaft 13 rotates during the energization time in step S16 of FIG. For example, after energization is started, when a prescribed number of pulses corresponding to the energization angle is given as a detection signal from the crank angle sensor 43, the ECU 6 determines that the crankshaft 13 has rotated the energization angle.

  When the crankshaft 13 rotates at the energization angle, the ECU 6 stops energizing the spark plug 18 (step S35) and controls the starter / generator 14 so that the crankshaft 13 rotates in the forward direction (step S36). ), The engine start process is terminated.

  On the other hand, when the crankshaft 13 is not rotating at the reverse rotation angle in step S31, the ECU 6 determines whether or not a first end time predetermined from the timeout setting in step S7 has elapsed (step S37). . If the first end time has not elapsed, the ECU 6 returns to the process of step S31. When the first end time has elapsed, the ECU 6 controls the starter / generator 14 so that the rotation of the crankshaft 13 in the reverse direction is stopped (step S38), and determines that an abnormality has occurred in the engine 10. The operator is warned (step S41), and the engine start process is terminated.

  In step S34, when the crankshaft 13 is not rotating at the energization angle, the ECU 6 determines whether or not a second end time set in advance has elapsed from the timeout setting in step S7 (step S37). The second end time is set longer than the first end time. If the second end time has not elapsed, the ECU 6 returns to the process of step S34. When the second end time has elapsed, the ECU 6 stops energizing the spark plug 18 (step S40), warns the driver that an abnormality has occurred in the engine 10 (step S41), and performs engine start processing. finish.

  Thus, in the second example, the reverse rotation of the crankshaft 13 is stopped based on the detection signal from the crank angle sensor 43 (steps S31 and S32). Further, the energization to the spark plug 18 is stopped based on the detection signal from the crank angle sensor 43 (steps S34 and S35). Thereby, reverse rotation of the crankshaft 13 and energization to the spark plug 18 can be stopped at an appropriate timing.

  If the second end time has elapsed in step S39 after the energization of the spark plug 18 is started in step S33, the energization of the spark plug 18 is stopped in step S40. This prevents energization of the spark plug 18 from continuing for a long time.

(5) Valve Drive Unit (5-1) Configuration A specific example of the valve drive unit 17 will be described. FIG. 9 is a schematic side view for explaining a specific example of the valve drive unit 17. 9 is a camshaft, and drives the intake valve 15 and the exhaust valve 16 of FIG. 2 via an intake rocker arm 510 (FIG. 10) and an exhaust rocker arm 520 (FIG. 10) described later. The valve drive unit 17 is rotatably provided in the cylinder head 32. The valve drive unit 17 has a sprocket 17a, and the crankshaft 13 has a sprocket 13a. An endless chain 25 is attached to the sprocket 13a and the sprocket 17a. Thereby, the rotation of the crankshaft 13 is transmitted to the valve drive unit 17 via the chain 25. The rotational speed of the valve drive unit 17 is half of the rotational speed of the crankshaft 13.

(5-2) Valve Drive FIG. 10 is a cross-sectional view of the valve drive unit 17 and its peripheral portion. In FIG. 10, the valve drive part 17 seen from the direction of arrow G of FIG. 9 is shown. As shown in FIG. 10, an intake rocker arm 510 and an exhaust rocker arm 520 are provided in the cylinder head 32. The intake rocker arm 510 is provided to be swingable about the shaft 511. A roller 512 is provided at one end of the intake rocker arm 510 and an adjuster 513 is provided at the other end. The roller 512 contacts the main intake cam 240 or the sub intake cam 245 of the valve drive unit 17. Details of the main intake cam 240 or the sub intake cam 245 will be described later. The adjuster 513 contacts the upper end portion of the intake valve 15. The intake valve 15 is urged in a direction to close the intake port 21 by a valve spring 15a. In this case, force is applied in the direction of pushing up the adjuster 513 from the intake valve 15 to the intake rocker arm 510. Accordingly, the roller 512 of the intake rocker arm 510 is pressed against the main intake cam 240 or the sub intake cam 245.

  The exhaust rocker arm 520 is provided to be swingable about the shaft 521. A roller 522 is provided at one end of the exhaust rocker arm 520 and an adjuster 523 is provided at the other end. The roller 522 contacts the exhaust cam 230 of the valve drive unit 17. Details of the exhaust cam 230 will be described later. The adjuster 523 contacts the upper end portion of the exhaust valve 16. The exhaust valve 16 is biased in a direction to close the exhaust port 23 by a valve spring 16a. As a result, a force is applied in the direction of pushing up the adjuster 523 from the exhaust valve 16 to the exhaust rocker arm 520, and the roller 522 of the exhaust rocker arm 520 is pressed against the exhaust cam 230.

  During the forward rotation of the crankshaft 13 (FIG. 9), the valve drive unit 17 rotates in the first direction Q1, and when the crankshaft 13 rotates in the reverse direction, the valve drive unit 17 rotates in the second direction Q2. As the valve drive unit 17 rotates, the main intake cam 240 and the sub intake cam 245 cause the intake rocker arm 510 to swing, and the exhaust cam 230 causes the exhaust rocker arm 520 to swing. As a result, the intake valve 15 opens and closes the intake port 21, and the exhaust valve 16 opens and closes the exhaust port 23.

  FIG. 11 is an external perspective view of the valve drive unit 17, and FIG. 12 is a cross-sectional view of the valve drive unit 17. 13 and 14 are partially exploded perspective views of the valve drive unit 17 as seen from different directions. As shown in FIGS. 11 and 12, the valve drive unit 17 includes a sprocket 17a, a shaft member 210, a spring fixing member 220, an exhaust cam 230, a sub intake cam 245, a spring fixing member 250, and a switching mechanism 300.

  As shown in FIGS. 13 and 14, the shaft member 210 has a substantially cylindrical shape and has a through hole 210 a along the axis. In the following description, the axial direction means a direction parallel to the axial center of the shaft member 210, and the circumferential direction means a circumferential direction centering on the axial center of the shaft member 210. A main intake cam 240 is integrally provided on the shaft member 210. An exhaust cam 230 and a spring fixing member 220 are attached to a portion of the shaft member 210 on one side of the main intake cam 240. A sub intake cam 245 and a spring fixing member 250 are attached to the shaft member 210 on the other side of the main intake cam 240.

  As shown in FIG. 13, a flange portion 211, a cam attachment portion 212, and a bearing portion 213 are provided in a portion of the shaft member 210 on one side of the main intake cam 240. The outer diameter of the cam mounting portion 212 is smaller than the outer diameter of the flange portion 211, and the outer diameter of the bearing portion 213 is smaller than the outer diameter of the cam mounting portion 212. A through hole 210b is formed in the cam attachment portion 212. As will be described later, the through hole 210a and the through hole 210b communicate with each other.

  The exhaust cam 230 has a substantially ring shape. The inner diameter of the exhaust cam 230 is substantially equal to the outer diameter of the cam mounting portion 212 of the shaft member 210. The exhaust cam 230 is positioned on the cam mounting portion 212 of the shaft member 210 so as to contact the flange portion 212. As will be described later, the exhaust cam 230 is provided to be rotatable in the circumferential direction within a certain angle range with respect to the shaft member 210.

  The spring fixing member 220 has a substantially cylindrical shape. The inner diameter of the spring fixing member 220 is substantially equal to the outer diameter of the bearing portion 213 of the shaft member 210. The spring fixing member 220 is positioned on the bearing portion 213 of the shaft member 210 so as to contact the side surface of the cam attachment portion 212. The spring fixing member 220 is provided so as not to rotate in the circumferential direction with respect to the shaft member 210.

  A flange portion 221 is provided at the end of the spring fixing member 220. A torsion coil spring 225 is disposed on the outer peripheral surface of the spring fixing member 220 excluding the flange portion 221. As shown in FIG. 12, one end portion of the torsion coil spring 225 is fixed to the flange portion 221 of the spring fixing member 220, and the other end portion is fixed to the side surface of the exhaust cam 230. The exhaust cam 230 is biased in the second direction Q2 (FIG. 10) by the torsion coil spring 225 with respect to the shaft member 210.

  As shown in FIG. 14, a cam attachment portion 214, a spring attachment portion 215, and a bearing portion 216 are provided on the portion of the shaft member 210 on the other side of the main intake cam 240. The outer diameter of the spring mounting portion 215 is smaller than the outer diameter of the cam mounting portion 214, and the outer diameter of the bearing portion 216 is smaller than the outer diameter of the spring mounting portion 215.

The sub intake cam 245 has a substantially ring shape. The inner diameter of the sub intake cam 245 is substantially equal to the outer diameter of the cam mounting portion 214 of the shaft member 210. The sub intake cam 245 is positioned on the cam mounting portion 214 of the shaft member 210 so as to contact the main intake cam 240. The sub intake cam 245 is formed with an elongated opening 246 along the circumferential direction. A fitting pin 241 (FIG. 12) is fixed to the main intake cam 240 so as to protrude to the other side. The tip of the fitting pin 241 is fitted into the opening 246 of the sub intake cam 245. Details of the sub intake cam 245 will be described later.

The spring fixing member 250 has a substantially ring shape. The inner diameter of the spring fixing member 250 is substantially equal to the outer diameter of the spring mounting portion 215 of the shaft member 210. The spring fixing member 250 is positioned on the spring mounting portion 215 so as to contact the side surface of the cam mounting portion 214. The spring fixing member 250 is provided so as not to rotate in the circumferential direction with respect to the shaft member 210.

  A protrusion 251 is provided at the end of the spring fixing member 250. A torsion coil spring 255 is disposed on the outer peripheral surface of the spring fixing member 250. As shown in FIG. 12, one end of the torsion coil spring 255 is fixed to the protrusion 251 of the spring fixing member 250, and the other end is fixed to the side surface of the sub intake cam 245. The sub intake cam 245 is biased by the torsion coil spring 255 in the first direction Q1 (FIG. 10) with respect to the shaft member 210.

  As shown in FIG. 12, the sprocket 17 a is disposed perpendicular to the axial direction at one end of the bearing portion 213 of the shaft member 210. An opening 17b is formed at the center of the sprocket 17a. Further, a thread is formed on the inner peripheral surface of one end of the through hole 210a. The bolt 260 is screwed into the through hole 210a through the opening 17b of the sprocket 17a. Thereby, the sprocket 17a is fixed to the shaft member 210.

  In the cylinder head 32 of FIG. 10, the bearing B <b> 1 is provided so as to contact the outer peripheral surface of the bearing portion 213 of the shaft member 210, and the bearing B <b> 2 is provided so as to contact the outer peripheral surface of the bearing portion 216. The shaft member 210 is rotatably held in the circumferential direction by the bearings B1 and B2.

  FIG. 15 is an external perspective view of the switching mechanism 300, and FIG. 16 is a cross-sectional view of the switching mechanism 300. As shown in FIGS. 15 and 16, the switching mechanism 300 includes a spring locking member 310, a spring 315, a moving member 320, a fitting member 330, a spring 335, a pressing mechanism 340, and a sliding mechanism 350.

  As shown in FIG. 16, the spring locking member 310 is disposed in the through hole 210 a of the shaft member 210 so as to face the tip of the bolt 260 of FIG. 12. One end of the spring 315 is locked to the spring locking member 310.

  The moving member 320 is disposed in the through hole 210 a of the shaft member 210 so as to be movable in the axial direction so as to be adjacent to the spring locking member 310. The moving member 320 includes a movement restraining portion 321, a spring locking portion 322, a first contact portion 323, a taper portion 324, a second contact portion 325, and a pressed portion 326. The movement restricting portion 321 is provided so as to protrude in the axial direction from the spring locking portion 322. The outer diameter of the spring locking portion 322 is larger than the outer diameter of the movement restraining portion 321 and is substantially equal to the inner diameter of the through hole 210a. A spring 315 is disposed so as to surround the outer peripheral surface of the movement stopping portion 321, and the other end portion of the spring 315 is locked to the spring locking portion 322.

  A tapered portion 324 is provided between the first and second contact portions 323 and 325. The outer diameter of the second contact portion 325 is larger than the outer diameter of the first contact portion 323. The tapered portion 324 is formed so that the outer diameter gradually increases from the first contact portion 323 toward the second contact portion 325. Thereby, the outer peripheral surface of the first contact portion 323 and the outer peripheral surface of the second contact portion 325 are connected via the outer peripheral surface of the tapered portion 324. The pressed portion 326 is provided at the other end of the moving member 320.

  A through hole 210b is formed in the shaft member 210 so as to intersect the through hole 210a perpendicularly. The through hole 210b opens on the outer peripheral surface of the cam mounting portion 212. The fitting member 330 is disposed in the through hole 210b. The fitting member 330 includes a contact portion 331 and a fitting portion 332. The outer diameter of the contact portion 331 is larger than the outer diameter of the fitting portion 332. The contact portion 331 has a contact surface that curves in a convex shape. The contact surface of the contact portion 331 contacts the first contact portion 323, the taper portion 324, or the second contact portion 325 of the moving member 320 according to the position of the moving member 320 in the axial direction. A spring 335 is disposed so as to surround the outer peripheral surface of the fitting portion 332. One end of the spring 335 is locked to the contact portion 331, and the other end is locked to a step portion formed at the end of the through hole 210b. In a state in which the contact portion 331 is in contact with the first contact portion 323, the fitting portion 332 of the fitting member 330 is accommodated in the through hole 210 b of the shaft member 210. On the other hand, when the contact portion 331 is in contact with the second contact portion 325, the fitting portion 332 of the fitting member 330 protrudes on the outer peripheral surface of the cam mounting portion 212 of the shaft member 210.

  FIG. 17 is an exploded perspective view of the pressing mechanism 340. As shown in FIG. 17, the pressing mechanism 340 includes a cover member 410, a rotating member 420, an annular member 430, spherical members 431 a and 431 b, a holding member 440 and a rod-like member 450. The cover member 410 has a substantially cylindrical shape. As shown in FIG. 16, the inner diameter of the cover member 410 is set so as to decrease stepwise from one end to the other end. As a result, step portions 411 and 412 are formed inside the cover member 410.

  As illustrated in FIG. 17, the rotating member 420 has a substantially cylindrical shape, and includes a ball receiving portion 421, a flange portion 422, and a sliding portion 423. A pair of grooves 424 a and 424 b extending spirally are provided symmetrically with respect to the axis of the rotating member 420 on the outer peripheral surface of the ball receiving portion 421. The holding member 440 has a substantially cylindrical shape and includes a ball holding portion 441 and a rod holding portion 442. The outer diameter and inner diameter of the ball holding portion 441 are larger than the outer diameter and inner diameter of the rod holding portion 442, respectively.

  As shown in FIG. 16, the rod-shaped member 450 is inserted into the rod holding portion 442 of the holding member 440. The rod holding portion 442 is inserted into the through hole 210 a of the shaft member 210. The rod-shaped member 450 is held by the rod holding portion 442 so as to extend in the axial direction of the shaft member 210. One end portion of the rod-shaped member 450 contacts the pressed portion 326 of the moving member 320 in the through hole 210a. A pair of concave portions 441 a and 441 b are formed on the inner peripheral surface of the ball holding portion 441 of the holding member 440. The spherical members 431a and 431b are fitted into the recesses 441a and 441b, respectively. In addition, the annular member 430 is disposed so as to come into contact with one end portion of the ball holding portion 441. The concave portions 441a and 441b of the ball holding portion 441 and the annular member 430 prevent the spherical members 431a and 431b from moving in the axial direction and the circumferential direction with respect to the ball holding portion 441. One end of the ball receiving portion 421 of the rotating member 420 is inserted into the ball holding portion 441 of the holding member 440, and the spherical members 431a and 431b are fitted into the grooves 424a and 424b, respectively. The other end of the rod-shaped member 450 is in contact with the end surface of the ball receiving portion 421 of the rotating member 420.

  Cover member 410 is attached to holding member 440 and rotating member 420 so as to cover the outer peripheral surface of ball holding portion 441 of holding member 440 and the outer peripheral surface of ball receiving portion 421 of rotating member 420. The inner diameter of one end portion of the cover member 410 is substantially equal to the outer diameter of the ball holding portion 441 and the annular member 430 of the holding member 440, and the inner diameter of the other end portion of the cover member 410 is outside the sliding portion 423 of the rotating member 420. It is almost equal to the diameter. The inner diameter of the intermediate portion of the cover member 410 is substantially equal to the outer diameter of the flange portion 422 of the rotating member 420.

  In the cover member 410, the annular member 430 contacts the step portion 411 of the cover member 410. Further, in the state of FIG. 16, the flange portion 422 of the rotating member 420 abuts on the step portion 412. The sliding portion 423 of the rotating member 420 protrudes in the axial direction from the other end portion of the cover member 410.

  The pressing mechanism 340 rotates integrally with the shaft member 210 except for the rotating member 420. The rotating member 420 is provided so as to be rotatable at a certain angle in the circumferential direction with respect to the shaft member 210.

  The sliding mechanism 350 includes a fixed member 351 and a sliding member 352. The fixing member 351 has a substantially cylindrical shape, and is fixed to the cylinder head 32 of FIG. 10 so as to surround the outer peripheral surface of the sliding portion 423 of the rotating member 420. The sliding member 352 has an annular shape and is attached to the inner peripheral surface of the fixing member 351. The sliding member 352 has elasticity and contacts the outer peripheral surface of the sliding portion 423 of the rotating member 420.

  As described above, the spherical members 431a and 431b are fitted into the spiral grooves 424a and 424b formed on the outer peripheral surface of the rotating member 420, respectively. Therefore, when the rotating member 420 rotates with respect to the shaft member 210, the rotating member 420 moves in the axial direction with respect to the shaft member 210. In the present embodiment, when the rotating member 420 rotates in the first direction Q1 with respect to the shaft member 210, the rotating member 420 moves in a direction away from the shaft member 210. On the other hand, when the rotating member 420 rotates in the second direction Q2 with respect to the shaft member 210, the rotating member 420 moves in a direction approaching the shaft member 210.

  During the forward rotation of the crankshaft 13, the fitting portion 332 of the fitting member 330 is maintained in a state of protruding on the outer peripheral surface of the cam mounting portion 212 of the shaft member 210 (hereinafter referred to as a rotation blocking state). On the other hand, when the crankshaft 13 rotates in the reverse direction, the fitting portion 332 of the fitting member 330 is maintained in a state of being accommodated in the through hole 210b of the shaft member 210 (hereinafter referred to as a rotatable state). The switching between the rotation preventing state and the rotatable state will be described later.

(5-3) Main Intake Cam and Sub Intake Cam FIG. 18 is a diagram for explaining the main intake cam 240 and the sub intake cam 245. As shown in FIGS. 18A and 18B, the fitting pin 241 attached to the main intake cam 240 is fitted into the opening 246 of the sub intake cam 245. The main intake cam 240 is provided integrally with the shaft member 210, and the sub intake cam 245 is rotatable with respect to the shaft member 210 in the circumferential direction. When the sub intake cam 245 rotates with respect to the shaft member 210, the fitting pin 241 moves in the circumferential direction within the opening 246. The angular range in which the sub intake cam 245 can rotate with respect to the shaft member 210 depends on the length of the opening 246.

  As shown in FIG. 18A, when the fitting pin 241 contacts the one end CA of the opening 246 of the sub intake cam 245, the rotation of the intake cam 245 in the first direction Q1 is stopped. In this state, the cam nose 245T of the sub intake cam 245 does not overlap the cam nose 240T of the main intake cam 240. The position of the sub intake cam 245 in FIG. 18A is an example of the first position.

  On the other hand, as shown in FIG. 18B, when the fitting pin 241 comes into contact with the other end CB of the opening 246 of the sub intake cam 245, the rotation of the intake cam 245 in the second direction Q2 is stopped. The In this state, the entire cam nose 245T of the sub intake cam 245 overlaps the cam nose 240T of the main intake cam 240. The position of the sub intake cam 245 in FIG. 18B is an example of the second position.

  The length from the axis of the shaft member 210 to the tip of the cam nose 240T is smaller than the length from the axis of the shaft member 210 to the tip of the cam nose 245T. Here, the distal end portion of the cam nose refers to a portion of the outer peripheral surface of the cam nose that has the maximum length from the shaft center of the shaft member 210. Further, in the following description, the rising portion of the cam nose is a boundary portion between the cam nose and another portion, and refers to a portion of the outer peripheral surface of the cam nose that has a minimum length from the shaft center of the shaft member 210.

  As described above, the sub intake cam 245 is biased in the first direction Q1 (FIG. 16) by the torsion coil spring 255 of FIG. The biasing force in the first direction Q1 applied to the sub intake cam 245 from the torsion coil spring 255 is the second direction applied as a reaction force from the intake rocker arm 510 of FIG. 10 to the sub intake cam 245 when the valve drive unit 17 rotates. Less than the force on Q2. Therefore, when a force in the second direction Q2 is applied from the intake rocker arm 510 to the sub intake cam 245 during the rotation of the valve drive unit 17, the sub intake cam 245 is within the range in which the sub intake cam 245 can rotate relative to the shaft member 210. 2 in the direction Q2.

  The operation of the main intake cam 240 and the sub intake cam 245 on the roller 512 of the intake rocker arm 510 of FIG. 10 will be described. FIG. 19 is a diagram for explaining the operation of the main intake cam 240 and the sub intake cam 245 when the crankshaft 13 rotates forward. FIG. 20 shows the main intake cam 240 and the sub intake cam 243 when the crankshaft 13 rotates reversely. It is a figure for demonstrating the effect | action of the intake cam. FIG. 21 is a diagram illustrating the lift amount of the intake valve 15.

  During forward rotation of the crankshaft 13, the shaft member 210 rotates in the first direction Q1. As shown in FIG. 19A, when neither the cam nose 245T of the sub intake cam 245 nor the cam nose 240T of the main intake cam 240 is in contact with the roller 512, the second direction from the roller 512 to the sub intake cam 245 is as follows. The power to Q2 is not added. In this case, the state in which the fitting pin 241 contacts the one end CA of the opening 246 of the sub intake cam 245 is maintained by the biasing force of the torsion coil spring 255 (FIG. 12). Further, the intake valve 15 in FIG. 10 is not lifted and the intake port 21 is closed. Hereinafter, the position of the roller 512 in a state where the intake valve 15 is not lifted is referred to as an initial position.

  As shown in FIG. 19B, when the rising portion of the cam nose 245T of the sub intake cam 245 contacts the roller 512, a force in the second direction Q2 is applied from the roller 512 to the sub intake cam 245. In this case, the sub intake cam 245 rotates in the second direction Q2 with respect to the shaft member 210 such that the rising portion of the cam nose 245T is in contact with the roller 512. Therefore, the roller 512 is not driven by the sub intake cam 245 and is maintained at the initial position.

  Subsequently, as shown in FIG. 19C, when the cam nose 240T of the main intake cam 240 reaches the roller 512, the cam nose 240T pushes up the roller 512. As a result, as shown in FIG. 21A, the intake valve 15 is lifted and the intake port 21 is opened in the range from the angle A12 to the angle A13.

  Subsequently, as shown in FIG. 19 (d), when the tip of the cam nose 240 T of the main intake cam 240 approaches the roller 512, the cam nose 245 T of the sub intake cam 245 is separated from the roller 512. In this case, the force in the second direction Q2 is not applied from the roller 512 to the sub intake cam 245. Therefore, the sub intake cam 245 rotates in the first direction Q1 with respect to the shaft member 210 by the biasing force of the torsion coil spring 255 (FIG. 12). As a result, the fitting pin 241 returns to a state where it is in contact with one end CA of the opening 246 of the sub intake cam 245. Thereafter, the operations of FIGS. 19A to 19D are repeated.

  As described above, when the crankshaft 13 rotates forward, the sub intake cam 245 does not drive the intake rocker arm 510, and only the main intake cam 240 drives the intake rocker arm 510. Therefore, the intake valve 15 in FIG. 10 is lifted and the intake port 21 is opened only in the range from the angle A12 to the angle A13 in FIG.

  When the crankshaft 13 rotates in the reverse direction, the shaft member 210 rotates in the second direction Q2. As shown in FIG. 20A, in a state where the roller 512 is not in contact with the cam nose 245T of the sub intake cam 245, the second input from the roller 512 to the sub intake cam 245 is similar to the state shown in FIG. No force in direction Q2 is applied. In this case, the state in which the fitting pin 241 contacts the one end CA of the opening 246 of the sub intake cam 245 is maintained by the biasing force of the torsion coil spring 255 (FIG. 12).

  As shown in FIG. 20B, when the cam nose 240T of the main intake cam 240 reaches the roller 512, the cam nose 240T pushes up the roller 512. As a result, as shown in FIG. 21B, the intake valve 15 is lifted and the intake port 21 is opened in the range from the angle A13 to the angle A12.

  Subsequently, as shown in FIG. 20C, when the cam nose 245T of the sub intake cam 245 reaches the roller 512, a force in the first direction Q1 is applied from the roller 512 to the sub intake cam 245. In this case, the state in which the fitting pin 241 contacts the one end CA of the opening 246 of the sub intake cam 245 is maintained, and the cam nose 245T pushes up the roller 512. As a result, as shown in FIG. 21B, the intake valve 15 is lifted and the intake port 21 is opened in the range from the angle A21 to the angle A22.

  Subsequently, as shown in FIG. 20D, when the contact position of the roller 512 exceeds the tip of the cam nose 245T, a force in the second direction Q2 is applied from the roller 512 to the sub intake cam 245. Accordingly, the sub intake cam 245 rotates in the second direction Q2 with respect to the shaft member 210, and the roller 512 returns to the initial position. In this case, as shown in FIG. 21B, the lift amount of the intake valve 15 sharply decreases at the angle A22.

  Thus, during reverse rotation of the crankshaft 13, both the main intake cam 240 and the sub intake cam 245 drive the intake rocker arm 510. Therefore, the intake valve 15 in FIG. 10 is lifted and the intake port 21 is opened in the range from the angle A13 to the angle A12 and the range from the angle A21 to the angle A22 in FIG.

  As a result, the opening / closing operation of the intake port 21 during the normal operation shown in FIG. 3 and the opening / closing operation of the intake port 21 during start-up shown in FIG. 4 are realized.

(5-4) Exhaust Cam FIG. 22 is a view for explaining the exhaust cam 230. As shown in FIG. 22A, a fitting pin 217 is fixed to the cam mounting portion 212 of the shaft member 210 so as to protrude from the outer peripheral surface in a direction perpendicular to the axial direction. A groove 231 is formed on the inner circumferential surface of the exhaust cam 230 along the circumferential direction. The tip of the fitting pin 217 is disposed in the groove 231 of the exhaust cam 230.

  When the exhaust cam 230 rotates with respect to the shaft member 210, the fitting pin 217 moves in the groove 231. The angular range in which the exhaust cam 230 can rotate with respect to the shaft member 210 depends on the length of the groove 231.

  As shown in FIG. 22A, the fitting pin 217 abuts against one end DA of the groove 231 of the exhaust cam 230, so that the rotation of the exhaust cam 230 with respect to the shaft member 210 in the second direction Q2 is stopped. . Further, as shown in FIG. 22B, the fitting pin 217 contacts the other end DB of the groove 231 of the exhaust cam 230, whereby the rotation of the exhaust cam 230 with respect to the shaft member 210 in the first direction Q1. Stopped. The position of the exhaust cam 230 in FIG. 22A is an example of the fourth position, and the position of the exhaust cam 230 in FIG. 22B is an example of the third position.

  A recess 232 is formed on the inner peripheral surface of the exhaust cam 230. In a state where the fitting pin 217 is in contact with one end portion DA of the groove 231 of the exhaust cam 230 (the state shown in FIG. 22A), the concave portion 232 is positioned on the extension line of the through hole 210b. In this state, when the fitting portion 332 of the fitting member 330 is fitted into the recess 232, the rotation of the exhaust cam 230 with respect to the shaft member 210 is prevented.

  As will be described later, during the forward rotation of the crankshaft 13, the switching mechanism 300 (FIG. 16) is maintained in the rotation blocking state. In this case, the fitting portion 332 of the fitting member 330 is fitted into the recess 232 in a state where the fitting pin 217 is in contact with one end portion DA of the groove 231 of the exhaust cam 230, and the rotation of the exhaust cam 230 with respect to the shaft member 210 is performed. Be blocked. On the other hand, during reverse rotation of the crankshaft 13, the switching mechanism 300 (FIG. 12) is maintained in a rotatable state. As a result, the exhaust cam 230 can rotate within a certain range with respect to the shaft member 210.

  As described above, the exhaust cam 230 is biased in the second direction Q2 by the torsion coil spring 225 of FIG. The urging force applied to the exhaust cam 230 from the torsion coil spring 225 in the second direction Q2 is applied to the first direction Q1 applied as a reaction force from the exhaust rocker arm 520 of FIG. Less than the power of. Therefore, when a force in the first direction Q1 is applied from the exhaust rocker arm 520 to the exhaust cam 230 during the rotation of the valve drive unit 17, the first cam is within the range in which the exhaust cam 230 can rotate with respect to the shaft member 210. It is rotated in the direction Q1.

  The action of the exhaust cam 230 on the roller 522 of the exhaust rocker arm 520 of FIG. 10 will be described. FIG. 23 is a diagram for explaining the operation of the exhaust cam 230 when the crankshaft 13 rotates forward, and FIG. 24 is a diagram for explaining the operation of the exhaust cam 230 when the crankshaft 13 rotates reversely. is there.

  During forward rotation of the crankshaft 13, as shown in FIGS. 23A to 23D, the exhaust cam 230 is in the state where the fitting pin 217 contacts the one end portion DA of the groove 231 of the exhaust cam 230. And rotate in the first direction Q1. In this case, the cam nose 230T of the exhaust cam 230 pushes up the roller 522. As a result, the exhaust valve 16 in FIG. 10 is lifted and the exhaust port 23 is opened in the range from the angle A15 to the angle A16 in FIG.

  FIG. 24A shows the state of the exhaust cam 230 when the crank angle is the angle A30 in FIG. 4, and FIG. 24D shows the exhaust when the crank angle is the angle A31 in FIG. The state of the cam 230 is shown. 24 (b) and 24 (c) show the state of the exhaust cam 230 between the state of FIG. 24 (a) and the state of FIG. 24 (d). As described above, the reverse rotation of the crankshaft 13 is performed in the range from the angle A30 to the angle A31 in FIG.

  When the crankshaft 13 rotates in the reverse direction, the exhaust cam 230 can rotate with respect to the shaft member 210. Further, the exhaust cam 230 is biased in the second direction Q2 by the torsion coil spring 225 of FIG. When the crank angle is at angle A30 in FIG. 4, the cam nose 230T of the exhaust cam 230 is not in contact with the roller 522, as shown in FIG. Therefore, a force in the first direction Q1 is not applied from the roller 522 to the exhaust cam 230, and the state in which the fitting pin 217 contacts the one end portion DA of the groove 231 is maintained by the biasing force of the torsion coil spring 225.

  Subsequently, as shown in FIG. 24B, when the rising portion of the cam nose 230T of the exhaust cam 230 comes into contact with the roller 522, a force in the first direction Q1 is applied from the roller 522 to the exhaust cam 230. The force in the first direction Q1 applied to the cam nose 230T from the roller 522 is larger than the force in the second direction Q2 applied to the exhaust cam 230 from the torsion coil spring 225. Therefore, as shown in FIG. 24C, the cam nose 230T does not push up the roller 522, and the state where the rising portion of the cam nose 230T is in contact with the roller 522 is maintained, and only the shaft member 210 rotates in the second direction Q2. To do.

  Thereafter, when the rotation of the shaft member 210 in the second direction Q2 is continued, the fitting pin 217 comes into contact with the other end DB of the groove 231 and the exhaust cam 230 rotates integrally with the shaft member 210. In that case, the roller 522 is pushed up by the cam nose 230T. However, in the present embodiment, even when the crank angle reaches the angle A31 in FIG. 4, the fitting pin 217 does not contact the other end DB of the groove 231 as shown in FIG. Therefore, when the crankshaft 13 rotates in the reverse direction, the exhaust rocker arm 520 is not driven and the exhaust port 23 is not opened.

  FIG. 25 is a diagram illustrating the operation of the exhaust cam 230 immediately after the rotation direction of the crankshaft 13 is switched from the reverse direction to the forward direction. Immediately after the rotation direction of the crankshaft 13 is switched from the reverse direction to the forward direction, the rising portion of the cam nose 230T comes into contact with the roller 522 and the fitting pin 217 is one end of the groove 231 as shown in FIG. Between the part DA and the other end DB. In this case, only the shaft member 210 rotates in the first direction Q1 while the state in which the rising portion of the cam nose 230T is in contact with the roller 522 is maintained by the biasing force of the torsion coil spring 225 of FIG.

  Thereafter, as shown in FIG. 25B, when the fitting pin 217 comes into contact with the one end portion DA of the groove 231, the switching mechanism 300 is switched to the rotation preventing state, and the rotation of the exhaust cam 231 with respect to the shaft member 210 is blocked. The Thereafter, as shown in FIG. 23, the exhaust cam 230 rotates integrally with the shaft member 210 to drive the exhaust rocker arm 520.

  As a result, the opening / closing operation of the exhaust port 23 during normal operation shown in FIG. 3 and the opening / closing operation of the exhaust port 23 during start-up shown in FIG. 4 are realized.

(5-5) Switching Mechanism FIG. 26 is a diagram for explaining the operation of the switching mechanism 300. FIG. 26A shows the switching mechanism 300 in a rotatable state, and FIG. 26B shows the switching mechanism 300 in a rotation blocking state. In FIG. 26, one direction in the axial direction is a third direction Q3, and the other direction is a fourth direction Q4. The third direction Q3 is a direction in which the moving member 320 approaches the spring locking member 310, and the fourth direction Q4 is a direction in which the moving member 320 moves away from the spring locking member 310.

  As shown in FIG. 26A, in the rotatable state, the flange portion 422 of the rotating member 420 abuts on the stepped portion 412 of the cover member 410 and the rod-shaped member 450 is accommodated in the holding member 440. In this case, the pressed portion 326 of the moving member 320 abuts on one end of the holding member 440, and the first abutting portion 323 of the moving member 320 is located on the extension line of the through hole 210 b of the shaft member 210. Thereby, the contact part 331 of the fitting member 330 contacts the first contact part 323 of the moving member 320, and the fitting part 322 is accommodated in the through hole 210b. The position of the fitting member 330 in FIG. 26A is an example of a rotatable position.

  As shown in FIG. 26B, in the rotation blocking state, the flange portion 422 of the rotating member 420 abuts on the annular member 30, and the rod-like member 450 protrudes from the one end portion of the holding member 440 in the third direction Q3. In this case, the second contact portion 325 of the moving member 320 is positioned on the extension line of the through hole 210b of the shaft member 210. As a result, the contact portion 331 of the fitting member 330 contacts the second contact portion 325 of the moving member 320, and the fitting portion 332 of the fitting member 330 moves from the outer peripheral surface of the cam mounting portion 212 of the shaft member 210. Protruding. Therefore, the fitting portion 332 of the fitting member 330 is fitted into the recess 232 of the exhaust cam 230 (FIG. 22). The position of the fitting member 330 in FIG. 26B is an example of the rotation stop position.

  Before the engine 10 is started, the switching mechanism 300 is in the rotation prevention state shown in FIG. When the engine 10 is started, the crankshaft 13 is rotated in the reverse direction, and the shaft member 210 is rotated in the second direction Q2. Each part of the switching mechanism 300 excluding the sliding mechanism 350 rotates with the shaft member 210 in the second direction Q2. In this case, a frictional force in the first direction Q1 acts on the sliding portion 423 of the rotating member 420 from the sliding member 352 of the sliding mechanism 350. Therefore, the rotating member 420 rotates in the first direction Q1 with respect to the shaft member 210 and moves in the fourth direction Q4 along the axial direction. The rotation of the rotating member 420 in the first direction Q1 and the movement in the fourth direction Q4 are stopped by the flange portion 422 of the rotating member 420 coming into contact with the stepped portion 412 of the cover member 410.

  When the rotating member 420 moves in the fourth direction Q4, the moving member 320 and the rod-shaped member 450 move in the fourth direction Q4 by the biasing force of the spring 315. Thereby, the rod-shaped member 450 is accommodated in the holding member 440, and the pressed portion 326 of the moving member 320 comes into contact with one end portion of the holding member 440. Further, the abutting portion 331 of the fitting member 330 abuts on the first abutting portion 323 of the moving member 320 by the biasing force of the spring 335. Thereby, the fitting part 332 of the fitting member 330 is accommodated in the through-hole 210b of the shaft member 210. In this way, the switching mechanism 300 is switched from the rotation prevention state shown in FIG. 26B to the rotatable state shown in FIG.

  Thereafter, the rotation direction of the crankshaft 13 is switched from the reverse direction to the forward direction, and the shaft member 210 is rotated to Q1 in the first direction. However, as shown in FIG. 25A, immediately after the rotation direction of the crankshaft 13 is switched from the reverse direction to the forward direction, the fitting pin 217 contacts the one end portion DA of the groove 231 of the exhaust cam 230. The recess 232 of the exhaust cam 230 is not positioned on the extension line of the through hole 210b of the shaft member 210. Accordingly, the fitting portion 332 of the fitting member 330 is maintained in a state of being accommodated in the through hole 210b of the shaft member 210.

  As shown in FIG. 25B, when the fitting pin 217 comes into contact with one end portion DA of the groove 231 of the exhaust cam 230, the switching mechanism 300 is changed from the rotatable state of FIG. Switch to the rotation prevention state. Specifically, when the shaft member 210 rotates in the first direction to Q1, the frictional force in the second direction Q2 is applied from the sliding member 352 of the sliding mechanism 350 to the sliding portion 423 of the rotating member 420. work. Therefore, the rotating member 420 rotates in the second direction Q2 with respect to the shaft member 210, and moves in the third direction Q3 along the axial direction. The rotation of the rotating member 420 in the second direction Q2 and the movement in the third direction Q3 are stopped by the flange portion 422 of the rotating member 420 coming into contact with the annular member 430.

  When the rotating member 420 moves in the third direction Q3, one end of the rod-shaped member 450 protrudes from the holding member 440 in the third direction Q3. As a result, the moving member 320 moves in the third direction Q3, and the movement restraining portion 321 of the moving member 320 contacts the spring locking member 310. Further, the contact portion 331 of the fitting member 330 is pressed in a direction away from the axis of the shaft member 210 by the tapered portion 324 of the moving member 320. Accordingly, the fitting member 330 moves in a direction away from the axial center of the shaft member 210 against the biasing force of the spring 335, and the fitting portion 332 of the fitting member 330 protrudes outside the through hole 210b. Thereby, the fitting part 332 of the fitting member 330 is fitted into the recess 232 of the exhaust cam 230 (FIG. 22). In this way, the switching mechanism 300 is switched from the rotatable state in FIG. 26A to the rotation preventing state in FIG.

(5-6) Another Example of Switching Mechanism FIG. 27 is a diagram for describing another example of the switching mechanism 300. The switching mechanism 300 of FIG. 27 will be described while referring to differences from the example of FIG. In the switching mechanism 300 of FIG. 27, the outer diameter of the first contact portion 323 of the moving member 320 is larger than the outer diameter of the second contact portion 325. The tapered portion 324 is formed such that the outer diameter gradually decreases from the first contact portion 323 toward the second contact portion 325. Thereby, the outer peripheral surface of the first contact portion 323 and the outer peripheral surface of the second contact portion 325 are connected via the outer peripheral surface of the tapered portion 324.

  As shown in FIG. 27A, when the contact portion 331 of the fitting member 330 is in contact with the first contact portion 323 of the moving member 320, the fitting portion 332 of the fitting member 330 is the shaft member 210. It protrudes from the outer peripheral surface of the cam mounting portion 212. As a result, the switching mechanism 300 enters a rotation blocking state. On the other hand, as shown in FIG. 27B, when the contact portion 331 of the fitting member 330 is in contact with the second contact portion 325 of the moving member 320, the fitting portion 332 of the fitting member 330 is pivoted. The member 210 is accommodated in the through hole 210b. Thereby, the switching mechanism 300 becomes a rotatable state.

  On the outer peripheral surface of the ball receiving portion 421 of the rotating member 420, spiral grooves 424c and 424d are formed instead of the grooves 424a and 424b in FIG. With respect to the axis of the rotating member 420, the spiral direction of the groove 424c is opposite to the spiral direction of the groove 424a, and the spiral direction of the groove 424d is opposite to the spiral direction of the groove 424b. A spherical member 431a is fitted into the groove 424c, and a spherical member 431b is fitted into the groove 424d.

  In this case, the rotating member 420 moves in the third direction Q3 by rotating in the first direction Q1 with respect to the shaft member 210. On the other hand, when the rotation member 420 rotates in the second direction Q2 with respect to the shaft member 210, the rotation member 420 moves in the fourth direction Q4.

  Before the engine 10 is started, the switching mechanism 300 is in the rotation prevention state shown in FIG. When the engine 10 is started, the crankshaft 13 is rotated in the reverse direction, and the shaft member 210 is rotated in the second direction Q2. As a result, a frictional force in the first direction Q1 acts on the sliding portion 423 of the rotating member 420 from the sliding member 352 of the sliding mechanism 350. Therefore, the rotating member 420 rotates in the first direction Q1 with respect to the shaft member 210 and moves in the third direction Q3 along the axial direction.

  When the rotating member 420 moves in the third direction Q3, one end of the rod-shaped member 450 protrudes from the holding member 440 in the third direction Q3. As a result, the moving member 320 moves in the third direction Q3, and the movement restraining portion 321 of the moving member 320 contacts the spring locking member 310. Further, the abutting portion 331 of the fitting member 330 abuts on the second abutting portion 325 of the moving member 320 by the biasing force of the spring 335. Accordingly, the fitting member 330 is accommodated in the through hole 210b of the shaft member 210. In this way, the switching mechanism 300 is switched from the rotation preventing state in FIG. 27A to the rotatable state in FIG.

  Thereafter, when the rotation direction of the crankshaft 13 is switched from the reverse direction to the forward direction, the shaft member 210 is rotated in the first direction Q1. Thereby, a frictional force in the second direction Q2 acts on the sliding portion 423 of the rotating member 420 from the sliding member 352 of the sliding mechanism 350. As shown in FIG. 25 (b), when the fitting pin 217 comes into contact with one end of the groove 231, the rotating member 420 rotates in the second direction Q2 with respect to the shaft member 210 and along the axial direction. To move in the fourth direction Q4.

  When the rotating member 420 moves in the fourth direction Q4, the moving member 320 and the rod-shaped member 450 move in the fourth direction Q4 by the biasing force of the spring 315. Thereby, the rod-shaped member 450 is accommodated in the holding member 440, and the pressed portion 326 of the moving member 320 comes into contact with one end portion of the holding member 440. Further, the contact portion 331 of the fitting member 330 is pressed in a direction away from the axis of the shaft member 210 by the tapered portion 324 of the moving member 320. Accordingly, the fitting member 330 moves in a direction away from the axial center of the shaft member 210 against the biasing force of the spring 335, and the fitting portion 332 of the fitting member 330 protrudes outside the through hole 210b. As a result, the fitting portion 332 of the fitting member 330 is fitted into the recess 232 of the exhaust cam 230 (FIG. 22). In this way, the switching mechanism 300 is switched from the rotatable state in FIG. 27B to the rotation preventing state in FIG.

(6) Effect In the engine system 200 according to the present embodiment, the crankshaft 13 is reversely rotated by the starter / generator 14 when the engine 10 is started. The intake valve 15 is driven by the valve drive unit 17 so that the fuel injected by the injector 19 is guided to the combustion chamber 31a during the reverse rotation of the crankshaft 13. Thereafter, the air-fuel mixture in the combustion chamber 31a is ignited by the spark plug 18 with the piston 11 approaching the compression top dead center.

  Thereby, the piston 11 is driven so that the crankshaft 13 rotates in the forward direction. Therefore, sufficient torque in the positive direction is obtained, and the piston 11 can easily exceed the compression top dead center. Therefore, the engine 10 can be started stably. Further, since a sufficient torque for starting the engine 10 can be obtained by ignition of the air-fuel mixture without using the large starter / generator 14, the engine 10 can be downsized. Furthermore, since it is not necessary to use a large starter / generator 14, it is possible to suppress the generation of excess power.

  Further, in the present embodiment, the intake valve 15 is driven by the valve drive unit 17 so that the intake port 21 is opened in the range from the angle A21 to the angle A22 only when the crankshaft 13 rotates in the reverse direction. Thus, the air-fuel mixture can be reliably introduced into the combustion chamber 31a when the crankshaft 13 rotates in the reverse direction while preventing the gas after combustion from flowing back into the intake passage 22 when the crankshaft 13 rotates in the forward direction.

  Further, in the present embodiment, the exhaust valve 16 is driven by the valve drive unit 17 so that the exhaust port 23 is not opened when the crankshaft 13 rotates in the reverse direction. Thus, the air-fuel mixture can be efficiently introduced into the combustion chamber 31a in the range from the angle A21 to the angle A22 during the reverse rotation of the crankshaft 13.

  Further, in the present embodiment, when the crankshaft 13 is rotated forward, fuel is injected by the injector 19 at an angle A11 located between the angle A0 and the angle A3. When the crankshaft 13 is rotated reversely, the angle A0 and the angle Fuel is injected by the injector tie 19 at an angle A23 located between A1. As a result, fuel is injected into the intake passage 22 before the intake port 21 is opened at each of forward rotation and reverse rotation of the crankshaft 13. As a result, the fuel can be appropriately introduced into the combustion chamber 31a.

  In the present embodiment, the air-fuel mixture in the combustion chamber 31a is ignited by the spark plug 18 after the rotation of the crankshaft 13 in the reverse direction is stopped at the angle A31. Thereby, the crankshaft 13 can be reliably rotated in the forward direction after the ignition of the air-fuel mixture.

  In the present embodiment, after ignition of the air-fuel mixture at the angle A31, the crankshaft 13 is driven in the forward direction by the starter / generator 14. As a result, a larger torque in the positive direction can be obtained. Therefore, the piston 11 can reliably exceed the compression top dead center.

(7) Other embodiments (7-1)
In the above embodiment, fuel is injected into the intake passage 22 by the injector 19 with the intake port 21 closed, and then the intake port 21 is opened to enter the combustion chamber 31a from the intake passage 22 through the intake port 21. The fuel is guided, but not limited to this. The fuel may be directly injected into the combustion chamber 31a through the intake port 21 by the injector 19 with the intake port 21 opened.

(7-2)
In the above embodiment, the intake port 21 is opened in the range from the angle A12 to the angle A13 in both the forward rotation and the reverse rotation of the crankshaft 13. However, the present invention is not limited to this. At the time of reverse rotation of the crankshaft 13, the intake port 21 does not have to be opened in the range from the angle A12 to the angle A13.

(7-3)
In the above embodiment, reverse rotation of the crankshaft 13 is started after the crank angle is adjusted to the angle A30. However, it is possible to introduce the air-fuel mixture into the combustion chamber 31a when the crankshaft 13 rotates reversely. For example, the reverse rotation of the crankshaft 13 may be started from an arbitrary position.

(7-4)
In the above embodiment, a camshaft is used as the valve drive unit 17, but is not limited thereto. For example, a hydraulic valve mechanism or an electromagnetic valve mechanism may be used as the valve drive unit 17.

(7-5)
In the above embodiment, the rotation of the crankshaft 13 in the range of two rotations (720 degrees) based on the crank angle detected by the crank angle sensor 43 and the pressure in the intake passage 22 detected by the intake pressure sensor 42. Although an angle is acquired, it is not restricted to this. For example, a cam angle sensor that detects a rotation angle of the valve drive unit 17 (hereinafter referred to as a cam angle) is provided, and a rotation angle in the range of two rotations of the crankshaft 13 is acquired based on the detection result of the cam angle sensor. May be. Alternatively, the rotation angle in the range of two rotations of the crankshaft 13 may be acquired based on the crank angle detected by the crank angle sensor 43 and the cam angle detected by the cam angle sensor. In this case, a more accurate rotation angle in the range of two rotations of the crankshaft 13 can be acquired.

(7-6)
In the above embodiment, the current flowing through the starter / generator 14 is detected by the current sensor 25. However, if the starter / generator 14 can be appropriately controlled, the current sensor 25 may not be provided.

(7-7)
The above embodiment is an example in which the present invention is applied to a motorcycle. However, the present invention is not limited to this, and the present invention is applied to other saddle riding type vehicles such as a motor tricycle or an ATV (All Terrain Vehicle). You may apply.

(8) Correspondence between each constituent element of claim and each element of the embodiment Hereinafter, an example of correspondence between each constituent element of the claim and each element of the embodiment will be described. It is not limited to.

  In the above embodiment, the engine system 200 is an example of an engine system, the engine 10 is an example of a single cylinder engine, the ECU 6 is an example of a control unit, the intake passage 22 is an example of an intake passage, and the injector 19 Is an example of a fuel injection device, the intake port 21 is an example of an intake port, the exhaust port 23 is an example of an exhaust port, the intake valve 15 is an example of an intake valve, and the exhaust valve 16 is an example of an exhaust valve. The valve drive unit 17 is an example of the valve drive unit. The combustion chamber 31a is an example of a combustion chamber, the spark plug 18 is an example of an ignition device, the crankshaft 13 is an example of a crankshaft, the starter / generator 14 is an example of a starter / power generation unit, Piston 11 is an example of a piston.

  Further, the shaft member 210 is an example of a shaft portion, the main intake cam 240 is an example of a first intake cam, the sub intake cam 245 is an example of a second intake cam, the opening 246 and the fitting pin 241. Is an example of the first limiting mechanism, the torsion coil spring 255 is an example of the first biasing member, the first direction Q1 is an example of the first direction, and the second direction Q2 is the second This is an example of the direction.

  The cam nose 240T is an example of a first cam nose, the cam nose 245T is an example of a second cam nose, the exhaust cam 230 is an example of an exhaust cam, the fitting member 330 is an example of a stop portion, The member 320 is an example of a moving part, the groove part 231 and the fitting pin 217 are examples of a second limiting mechanism, and the torsion coil spring 225 is an example of a second urging member. The motorcycle 100 is an example of a saddle-ride type vehicle, the rear wheel 7 is an example of a driving wheel, and the vehicle body 1 is an example of a main body.

  As each constituent element in the claims, various other elements having configurations or functions described in the claims can be used.

  The present invention can be effectively used for various vehicles.

1 Car body 3 Front wheel 6 ECU
7 Rear wheel 10 Engine 11 Piston 12 Connecting rod 13 Crankshaft 14 Starter / generator 15 Intake valve 16 Exhaust valve 17 Valve drive 17a Sprocket 18 Spark plug 19 Injector 21 Intake port 22 Intake passage 23 Exhaust port 24 Exhaust passage 31 Cylinder 31a Combustion chamber 41 Starter switch 42 Intake pressure sensor 43 Crank angle sensor 44 Current sensor 100 Motorcycle 200 Engine system 210 Shaft member 220, 250 Spring fixing member 225, 255 Torsion coil spring 230 Exhaust cam 240 Main intake cam 245 Sub intake cam 300 Switching Mechanism 310 Spring locking member 315, 335 Spring 320 Moving member 330 Fitting member 340 Pressing mechanism 350 Sliding mechanism

Claims (16)

A single cylinder engine,
A control unit configured to control the single-cylinder engine,
The single cylinder engine
A fuel injection device disposed in the intake passage;
A valve drive unit configured to drive an intake valve that opens and closes the intake port and an exhaust valve that opens and closes the exhaust port; and
An ignition device configured to ignite an air-fuel mixture in the combustion chamber;
A starting and power generating unit provided on a crankshaft, configured to rotate the crankshaft in a forward direction or a reverse direction and generate electric power by rotation of the crankshaft,
The control unit controls the starting and generating unit to rotate the crankshaft in the reverse direction at the time of starting,
The valve drive unit guides the fuel injected by the fuel injection device into the combustion chamber from the intake passage through the intake port at a first time point in a period in which the crankshaft is rotated in the reverse direction. Drive the intake valve so that
After the fuel is introduced into the combustion chamber at the first time point, the control unit is in a state where the air-fuel mixture is compressed in the combustion chamber by the rotation of the crankshaft in the reverse direction and the piston is compressed. An engine system that controls the ignition device to ignite the air-fuel mixture at a second time that does not reach dead center. 2. The engine system according to claim 1, wherein the first time point is included in a period in which the piston descends from exhaust top dead center when the crankshaft rotates in the reverse direction. The valve drive unit is
When the crankshaft rotates in the positive direction, the exhaust valve is driven so that the exhaust port is opened during a period in which the rotation angle of the crankshaft is in the first range, and the rotation angle of the crankshaft is Driving the intake valve so that the intake port is opened during a period in the range of 2,
Driving the intake valve so that the intake port is opened during a period in which the rotation angle of the crankshaft is in a third range within the first range when the crankshaft rotates in the reverse direction;
The engine system according to claim 1 or 2, wherein the third range is larger than a portion of the second range in the first range. The engine system according to claim 3, wherein there is an interval between the second range and the third range. The valve drive unit is
5. The exhaust valve is driven so that the exhaust port is not opened during a period in which the rotation angle of the crankshaft is at least in the third range when the crankshaft rotates in the reverse direction. Engine system. The control unit is configured to inject fuel when the crankshaft rotates in the forward direction and when the crankshaft is in a fourth range, and when the crankshaft rotates in the reverse direction, The engine system according to any one of claims 3 to 5, wherein the fuel injection device is controlled so that fuel is injected when a rotation angle of the fuel is in a fifth range different from the fourth range. The engine system according to claim 6, wherein the fifth range is set so as to be positioned more advanced than the fourth range when the crankshaft rotates in the reverse direction. The engine system according to claim 6 or 7, wherein the fifth range is within the second range. The valve drive unit is
A shaft provided to rotate in conjunction with rotation of the crankshaft;
A first intake cam provided to rotate integrally with the shaft portion and configured to act on the intake valve;
A second intake cam provided rotatably with respect to the shaft portion and configured to act on the intake valve;
A first limiting mechanism configured to limit movement of the second intake cam relative to the shaft portion;
A first biasing member configured to bias the second intake cam;
The first restricting mechanism stops the rotation of the second intake cam in the first direction at a first position of the shaft portion, and the second restriction cam in the second direction opposite to the first direction. Provided to stop the rotation of the second intake cam at the second position of the shaft portion;
The second intake cam is configured to act on the intake valve at the first position and not to act on the intake valve at the second position;
The first biasing member is configured to bias the second intake cam in the first direction,
When the crankshaft rotates in the positive direction, a reaction force larger than the urging force of the first urging member is applied from the intake valve to the second intake cam, whereby the second intake cam is moved to the second intake cam. Moved in the direction of 2,
When the crankshaft rotates in the reverse direction, the intake cam is moved to the first position by the urging force of the first urging member so that the second intake cam acts on the intake valve. The engine system according to any one of claims 3 to 8. The first intake cam has a first cam nose;
The second intake cam has a second cam nose;
When the second intake cam is in the second position, the entire second cam nose overlaps with the first cam nose, and when the second intake cam is in the first position, The engine system according to claim 9, wherein at least a part of the two cam noses does not overlap the first cam nose. The valve drive unit is
An exhaust cam provided rotatably with respect to the shaft portion and configured to act on the exhaust valve;
It is movable between a rotation stopping position that stops rotation of the exhaust cam relative to the shaft portion at a predetermined position of the shaft portion, and a rotatable position that enables rotation of the exhaust cam relative to the shaft portion. The provided restraining part,
A moving part that moves the stopping part to the rotation stopping position when the crankshaft rotates in the forward direction, and moves the stopping part to the rotatable position when the crankshaft rotates in the reverse direction; The engine system according to claim 9 or 10. The valve drive unit is
A second limiting mechanism configured to limit the movement of the exhaust cam relative to the shaft portion;
The second restricting mechanism stops rotation of the exhaust cam in the first direction at a third position of the shaft portion, and prevents rotation of the exhaust cam in the second direction of the shaft portion. Provided to stop at the fourth position,
When the crankshaft rotates in the reverse direction, a reaction force is applied from the exhaust valve to the exhaust cam, whereby the exhaust cam is moved in the first direction,
The engine system according to claim 11, wherein the stopping portion stops the exhaust cam at the fourth position at the rotation stopping position. The valve drive unit further includes a second biasing member configured to bias the exhaust cam in the second direction,
13. The engine system according to claim 12, wherein a biasing force of the second biasing member is smaller than a reaction force in a first direction applied from the exhaust valve to the exhaust cam when the crankshaft rotates in the reverse direction. . The engine system according to any one of claims 1 to 13, wherein the control unit ignites the air-fuel mixture by the ignition device in a state where the crankshaft rotates in the positive direction at the second time point. The engine system according to claim 14, wherein the control unit drives the crankshaft in the positive direction by the starter / power generation unit after the second time point. A main body having a drive wheel;
A straddle-type vehicle comprising: the engine system according to any one of claims 1 to 15 that generates power for rotating the drive wheels.

Images