TW201625844A - Engine system and straddled vehicle - Google Patents

Abstract

During start-up of an engine, an engine unit is controlled to perform a reverse rotation start-up operation. In the reverse rotation start-up operation, a fuel-air mixture is introduced into a combustion chamber while a crankshaft is rotated in a reverse direction, and the fuel-air mixture is ignited such that the crankshaft is driven in a forward direction. In the reverse rotation start-up operation, an ignition threshold value is set based on a first parameter corresponding to friction of the engine, and the fuel-air mixture in the combustion chamber is ignited when a second parameter corresponding to pressure in the combustion chamber reaches the set ignition threshold value.

Description

Engine system and straddle type vehicle

The present invention relates to an engine system and a straddle type vehicle having the same.

In a straddle type vehicle such as a locomotive, when the engine is started, a large torque is required in order to make the crank angle exceed an angle corresponding to the first compression top dead center. Therefore, in order to improve the startability of the engine, there is a technique of rotating the crankshaft in the reverse direction.

In the engine system described in Japanese Laid-Open Patent Publication No. 2014-77405, when the engine is started, the mixture is introduced into the combustion chamber while rotating the crankshaft in the reverse direction. The ignition operation is performed by the ignition device in a state where the mixed gas is compressed in the combustion chamber. Thereby, the mixed gas is burned, and the crankshaft is rotationally driven in the forward direction by the energy of combustion.

The inventors and the like have found through various experiments and analyses that the pressure in the combustion chamber is uneven during the above-described ignition operation. When the pressure in the combustion chamber during ignition is not appropriate, even if the mixture is burned, sufficient energy cannot be obtained. Therefore, the engine cannot be properly started.

It is an object of the present invention to provide an engine system and a straddle type vehicle that can properly start an engine.

(1) An engine system according to an aspect of the present invention includes: an engine unit including an engine and a rotary drive unit; a friction detecting unit that detects a first parameter corresponding to friction of the engine; and a pressure detecting unit that detects the engine The second parameter corresponding to the pressure in the combustion chamber; and control a unit that controls the engine unit based on the first parameter detected by the friction detecting unit and the second parameter detected by the pressure detecting unit; and the engine includes: a fuel injection device that injects fuel to The air is introduced into the intake passage of the combustion chamber; the ignition device is configured to ignite the mixture in the combustion chamber; and the valve drive portion is driven to open and close the air inlet respectively. The intake valve and the exhaust valve for opening and closing the exhaust port are configured; and the rotary drive portion is configured to rotationally drive the crankshaft in the forward direction and the reverse direction, and the control portion is reversed when the engine is started. The engine unit is controlled to rotate the starting operation, and in the reverse rotation starting operation, the mixture is introduced into the combustion chamber while rotating the crankshaft in the reverse direction, and the mixture is driven in the positive direction. In the reverse rotation start operation, the control unit sets the ignition threshold based on the first parameter detected by the friction detecting unit, and is detected by the pressure detecting unit. The second set of parameters to achieve the controlled ignition of an ignition device when the ignition threshold.

In the engine system, when the engine is started, the mixture is introduced into the combustion chamber while rotating the crankshaft in the reverse direction, and the mixture is burned by igniting the introduced mixture. The crankshaft is driven in the positive direction by utilizing the energy generated by the combustion.

In this case, the ignition threshold is set based on the first parameter corresponding to the friction of the engine, and when the second parameter corresponding to the pressure in the combustion chamber of the engine reaches the ignition threshold, the ignition of the mixture is performed by the ignition device. Thereby, when the pressure in the combustion chamber is an appropriate value corresponding to the friction of the engine, the mixed gas in the combustion chamber can be ignited. Therefore, sufficient energy for driving the crankshaft in the positive direction can be obtained by the combustion of the mixed gas. As a result, the engine can be started appropriately.

(2) The first parameter may also be a value corresponding to the temperature of the engine. Since the temperature of the engine is higher, the friction of the engine is smaller, so that appropriate control corresponding to the friction of the engine can be performed based on the value corresponding to the temperature of the engine.

(3) The second parameter may also be a current flowing to the rotary drive unit. Since the current flowing to the rotary drive unit becomes large when the pressure in the combustion chamber becomes large, the mixed gas in the combustion chamber can be ignited when the pressure in the combustion chamber is an appropriate value based on the current flowing to the rotary drive unit.

(4) The second parameter can also be the crank angle of the engine. Since the pressure in the combustion chamber depends on the crank angle, the mixture in the combustion chamber can be ignited based on the crank angle when the pressure in the combustion chamber is an appropriate value.

(5) The second parameter may also be a value indicating a change in the rotational speed of the crankshaft. Since the pressure in the combustion chamber depends on the change in the rotational speed of the crankshaft, the mixture in the combustion chamber can be ignited based on the value representing the change in the rotational speed of the crankshaft when the pressure in the combustion chamber is an appropriate value.

(6) The control unit may adjust the torque generated by the rotation driving unit based on the first parameter detected by the friction detecting unit during the reverse rotation starting operation.

In this case, the crankshaft can be reversely rotated in such a manner that the second parameter reaches the ignition threshold without excessively consuming power by the rotation driving unit.

(7) A straddle-type vehicle according to another aspect of the present invention includes: a body portion having a drive wheel; and the engine system that generates power for rotating the drive wheel.

In the straddle type vehicle, since the engine system described above is used, the engine can be appropriately started.

1‧‧‧ body

2‧‧‧ front fork

3‧‧‧ Front wheel

4‧‧‧Hands

5‧‧‧

6‧‧‧ ECU (engine control unit)

7‧‧‧ Rear wheel

10‧‧‧ engine

11‧‧‧Piston

12‧‧‧ Connecting rod

13‧‧‧ crankshaft

14‧‧‧Starting and generator

15‧‧‧Intake valve

16‧‧‧Exhaust valve

17‧‧‧ Valve Drive Department

18‧‧‧Mars plug

19‧‧‧Injector

21‧‧‧Air inlet

22‧‧‧Intake passage

23‧‧‧Exhaust port

24‧‧‧Exhaust passage

31‧‧‧ cylinder

31a‧‧‧ combustion chamber

40‧‧‧Main switch

41‧‧‧Start switch

42‧‧‧Intake pressure sensor

43‧‧‧Crank angle sensor

44‧‧‧ Current Sensor

45‧‧‧Temperature Sensor

100‧‧‧ locomotive

200‧‧‧Engine system

A0‧‧‧ angle

A1‧‧‧ angle

A2‧‧‧ angle

A3‧‧‧ angle

A11‧‧‧ angle

A12‧‧‧ angle

A13‧‧‧ angle

A14‧‧‧ angle

A15‧‧‧ angle

A16‧‧‧ angle

A21‧‧‧ angle

A22‧‧‧ angle

A23‧‧‧ angle

A30‧‧‧ angle

A31‧‧‧ angle

A31a‧‧‧ angle

A31s‧‧‧ angle

A31t‧‧‧ angle

P1, P2, P3, P4‧‧‧ arrows

P5, P6, P7, P8‧‧‧ arrows

Ps, Psa, V3, V4‧‧‧ values

R1‧‧‧ arrow

R2‧‧‧ arrow

Vt, Vta‧‧ ignition threshold

Fig. 1 is a schematic side view showing a schematic configuration of a locomotive according to an embodiment of the present invention.

Fig. 2 is a schematic view for explaining the configuration of an engine system.

FIG. 3 is a diagram for explaining a normal operation of an engine unit.

Fig. 4 is a view for explaining a reverse rotation starting operation of an engine unit.

Figure 5 (a) ~ (c) is used to properly start the engine by the reverse rotation start action A diagram illustrating the situation.

6(a) to 6(c) are diagrams for explaining a case where the engine is started properly without using the reverse rotation start operation.

Fig. 7 is a view showing an example of a threshold setting map.

8(a) to 8(c) are schematic diagrams for explaining the setting of the ignition threshold.

Fig. 9 is a view showing an example of a drive duty ratio setting map.

10(a) to (c) are schematic diagrams for explaining the setting of the target crank angle.

Figure 11 is a flow chart of the engine startup process.

Figure 12 is a flow chart of the parameter setting process.

Hereinafter, a locomotive as an example of a straddle type vehicle according to an embodiment of the present invention will be described with reference to the drawings.

(1) Locomotive

Fig. 1 is a schematic side view showing a schematic configuration of a locomotive according to an embodiment of the present invention. In the locomotive 100 of Fig. 1, a front fork 2 is swingably provided in the front-rear direction of the vehicle body 1. A handle 4 is attached to the upper end of the front fork 2, and a front wheel 3 is rotatably mounted to the lower end of the front fork 2.

A seat portion 5 is provided at a substantially central upper portion of the vehicle body 1. An ECU (Engine Control Unit) 6 and an engine unit EU are provided below the seat portion 5. The engine unit EU contains an engine 10 such as a single cylinder. The engine system 200 is constituted by the ECU 6 and the engine unit EU. A rear wheel 7 is attached to a lower portion of the rear end of the vehicle body 1 and the rear wheel 7 is rotatable. The rear wheel 7 is rotationally driven by utilizing 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 unit EU includes an engine 10 and a starter-generator 14. The engine 10 is provided with a piston 11, a connecting rod 12, a crank shaft 13, an intake valve 15, an exhaust valve 16, and a valve. The drive unit 17, the spark plug 18, and the injector 19.

The piston 11 is provided to be reciprocally movable within the cylinder 31 and is coupled to the crankshaft 13 via a connecting rod 12. The reciprocating movement of the piston 11 is converted into a rotational movement of the crankshaft 13. A starter-generator 14 is provided to the crankshaft 13. The starter-generator 14 is a generator having a function of activating a motor, and drives the crankshaft 13 in the forward direction and the reverse direction, and generates electric power by the rotation of the crankshaft 13. The positive direction is the direction of rotation of the crankshaft 13 during normal operation of the engine 10, and the opposite direction is the opposite direction. The starter-generator 14 directly transmits torque to the crankshaft 13 without passing through the reducer. The rear wheel 7 is rotationally driven by transmitting the positive direction of the crankshaft 13 (forward rotation) to the rear wheel 7. Instead of the starter-generator 14, a starter motor and a generator may be separately provided.

A combustion chamber 31a is formed on the piston 11. The combustion chamber 31 a communicates with the intake passage 22 via the intake port 21 , and communicates with the exhaust passage 24 via 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 the valve drive unit 17. A throttle valve TV for adjusting the flow rate of the air flowing in from the outside is provided in the intake passage 22. The Mars plug 18 is constructed to ignite the 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. You can also use a microcomputer instead of a CPU and memory. The main switch 40, the start switch 41, the intake pressure sensor 42, the crank angle sensor 43, the current sensor 44, and the temperature sensor 45 are electrically connected to the ECU 6. The main switch 40 is disposed, for example, below the handle 4 of FIG. 1, and the start switch 41 is disposed, for example, with the handle 4 of FIG. The main switch 40 and the start switch 41 are operated by a rider. The intake pressure sensor 42 detects the pressure within the intake passage 22. The crank angle sensor 43 detects the rotational position of the crankshaft 13 (hereinafter referred to as a crank angle). The current sensor 44 detects a current flowing to the starter-generator 14 (hereinafter, referred to as a motor current). The temperature sensor 45 detects, for example, the water temperature or oil temperature in the engine 10, or the machine temperature as the temperature corresponding to the temperature of the engine 10. The value (hereinafter, referred to as the engine temperature).

The operations of the main switch 40 and the start switch 41 are applied to the ECU 6, the intake pressure sensor 42, the crank angle sensor 43, the current sensor 44, and the temperature sensor 45 in the form of an operation signal to detect the signal. The form is given to the ECU 6. The ECU 6 controls the starter-generator 14, the spark plug 18, and the injector 19 based on the operation signal and the detection signal to be applied.

(3) Engine action

For example, by turning on the main switch 40 of FIG. 2 and turning on the start switch 41, the engine 10 is started, and the engine 10 is stopped by turning off the main switch 40 of FIG. Further, the engine 10 is automatically stopped by satisfying the predetermined idle stop condition, and thereafter, the engine 10 can be automatically restarted by satisfying the predetermined idle stop release condition. The idle stop condition includes, for example, conditions relating to at least one of a throttle opening degree (opening degree of the throttle valve TV), a vehicle speed, and a rotational speed of the engine 10. The idle stop release condition is, for example, operation of the accelerator grip and the throttle opening becomes greater than zero. Hereinafter, a state in which the engine 10 is automatically stopped by satisfying the idle stop condition is referred to as an idle stop state.

The engine unit EU performs a reverse rotation start action when the engine 10 is started. Thereafter, the engine unit EU performs a normal operation. FIG. 3 is a view for explaining a normal operation of the engine unit EU. Fig. 4 is a view for explaining a reverse rotation starting operation of the engine unit EU.

In the following description, the top dead center of the piston 11 when passing from the compression stroke to the expansion stroke is referred to as the compression top dead center, and the piston 11 is referred to as the top dead center when moving from the exhaust stroke to the intake stroke. For the exhaust to the dead end. The dead point passing through the piston 11 during the transition from the intake stroke to the compression stroke is referred to as the intake bottom dead center, and the dead point of the piston 11 when the self-expanding stroke is moved to the exhaust stroke is referred to as expansion. Dead point.

In FIGS. 3 and 4, the rotation angle of the crankshaft 13 in the range of 2 rotations (720 degrees) is indicated by one circle. The rotation of the crankshaft 13 by two turns corresponds to one cycle of the engine 10. The crank angle sensor 43 of Fig. 2 detects the rotational position of the crankshaft 13 in the range of one rotation (360 degrees). ECU6 Based on the pressure in the intake passage 22 detected by the intake pressure sensor 42, the rotational position detected by the crank angle sensor 43 and the rotation of the crank shaft 13 corresponding to one cycle of the engine 10 are determined. Which of the 2 circles corresponds to which circle. Thereby, the ECU 6 can acquire the rotational position of the crankshaft 13 in the range of 2 rotations (720 degrees).

In FIGS. 3 and 4, the angle A0 is the crank angle at which the piston 11 (FIG. 2) is at the top dead center of the exhaust, the angle A2 is the crank angle at which the piston 11 is at the top dead center, and the angle A1 is the piston 11 The crank angle at the bottom of the air, the angle A3 is the crank angle at which the piston 11 is at the bottom dead center. The arrow R1 indicates the direction in which the crank angle changes in the forward rotation of the crank shaft 13, and the arrow R2 indicates the direction in which the crank angle changes in the reverse rotation of the crank shaft 13. Arrows P1 to P4 indicate the moving direction of the piston 11 when the crankshaft 13 rotates in the forward direction, and arrows P5 to P8 indicate the moving direction of the piston 11 when the crankshaft 13 rotates in the reverse direction.

(3-1) Normal action

The normal operation of the engine unit EU will be described with reference to FIG. In the normal operation, the crankshaft 13 (Fig. 2) rotates in the positive direction. Therefore, the crank angle changes in the direction of the arrow R1. In this case, as shown by the arrows P1 to P4, the piston 11 (FIG. 2) descends from the angle A0 to the angle A1, and the piston 11 rises from the angle A1 to the angle A2, from the angle A2. The piston 11 is lowered in the range up to the angle A3, and the piston 11 is raised in the range from the angle A3 to the angle A0.

At angle A11, fuel is injected into intake passage 22 (Fig. 2) by injector 19 (Fig. 2). In the positive direction, the angle A11 is located closer to the advanced angle side than the angle A0. Then, 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 located closer to the retarded side than the angle A11 and closer to the advanced side than the angle A0, and the angle A13 is located closer to the retarded side than the angle A1. The range from the angle A12 to the angle A13 is an example of the normal intake range. Thereby, the mixed gas containing air and fuel is introduced into the combustion chamber 31a (FIG. 2) through the intake port 21.

Secondly, at angle A14, the mixture in the combustion chamber 31a (Fig. 2) is made by the spark plug 18 (Fig. 2). Syngas is used to ignite. In the positive direction, the angle A14 is located closer to the advanced angle side than the angle A2. An explosion (combustion of the mixed gas) is generated in the combustion chamber 31a by igniting the mixed gas. The energy of the combustion of the mixed gas becomes the driving force of the piston 11. Thereafter, the exhaust port 23 (Fig. 2) is opened by the exhaust valve 16 (Fig. 2) in a range from the angle A15 to the angle A16. In the positive direction, the angle A15 is located closer to the advance angle side than the angle A3, and the angle A16 is located closer to the retard angle side than the angle A0. The range from the angle A15 to the angle A16 is an example of a normal exhaust range. Thereby, the burned gas is discharged from the combustion chamber 31a through the exhaust port 23.

(3-2) Reverse rotation start action

The reverse rotation starting operation of the engine unit EU will be described with reference to FIG. In this example, the crank angle is adjusted to a predetermined inversion start range before the reverse rotation start operation is performed. The inversion start range is, for example, in a range from the angle A0 to the angle A2 in the positive direction, and is preferably in a range from the angle A13 to the angle A2. In FIG. 4, the inversion start range is the angle A30. The angle A30 is a range from the angle A13 to the angle A2.

In the reverse rotation starting operation, the crankshaft 13 is rotated in the reverse direction from the state in which the crank angle is in the reverse rotation start range. Thereby, the crank angle changes in the direction of the arrow R2. In this case, as indicated by arrows P5 to P8, the piston 11 descends from the angle A2 to the angle A1, and the piston 11 rises from the angle A1 to the angle A0, from the angle A0 to the angle A3. The range piston 11 is lowered, and the piston 11 rises from the angle A3 to the angle A2. When the crank shaft 13 is rotated in the reverse direction, the moving direction of the piston 11 is opposite to the moving direction of the piston 11 when the crankshaft 13 is rotated in the forward direction.

In the present example, even when the crankshaft 13 is rotated in the reverse direction, the intake port 21 is opened in the range from the angle A13 to the angle A12 as in the case of the forward rotation, and is from the angle A16 to the angle A15. The range opens the exhaust port 23. However, when the crankshaft 13 is rotated in the reverse direction, the intake port 21 may not be opened in a range from the angle A13 to the angle A12, or the exhaust port 23 may not be opened in a range from the angle A16 to the angle A15.

At angle A23, fuel is injected into intake passage 22 (Fig. 2) by injector 19 (Fig. 2). In the opposite direction, the angle A23 is located closer to the advanced angle side than the angle A0. Further, in 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). The range from the angle A21 to the angle A22 is an example of starting the intake range. In the opposite direction, the angles A21 and A22 are in the range from the angle A0 to the angle A3. Since the piston 11 rises in a range from the angle A1 to the angle A0, even if the intake port 21 is opened in a range from the angle A13 to the angle A12, air and fuel are hardly introduced into the combustion chamber 31a. On the other hand, since the piston 11 is lowered in the range from the angle A0 to the angle A3, the air inlet 21 is opened by the range from the angle A21 to the angle A22, and the air and fuel mixture is contained from the intake passage 22. The gas is introduced into the combustion chamber 31a through the intake port 21.

Then, at the angle A31a, the ignition coil connected to the Mars plug 18 (Fig. 2) is energized, and at the angle A31, the mixture in the combustion chamber 31a is ignited by the spark plug 18 (Fig. 2). In the opposite direction, the angle A31a is located closer to the advanced angle side than the angle A31, and the angle A31 is located closer to the advanced angle side than the angle A2. The angle A31 is an example of starting the ignition range. In the present embodiment, when the motor current detected by the current sensor 44 of FIG. 2 reaches the threshold value, the mixture gas is ignited by the spark plug 18. See below for details on ignition control.

Further, at the angle A31, the rotation direction of the crankshaft 13 is switched from the reverse direction to the positive direction. In this case, the torque in the positive direction of the crankshaft 13 is increased by the combustion of the mixed gas. Thereafter, the engine 10 moves to the normal action of FIG.

In the present embodiment, the mixture in the combustion chamber 31a is ignited by the spark plug 18 while the reverse rotation of the crankshaft 13 is stopped. However, as long as the crankshaft 13 can be driven in the positive direction, the crankshaft 13 is driven. The stop of the reverse rotation and the ignition by the spark plug 18 may also be performed at different times.

As described above, in the present embodiment, when the engine 10 is started, the startup is concurrently initiated. The motor 14 introduces the mixed gas into the combustion chamber 31a while rotating the crankshaft 13 in the reverse direction, and then ignites the mixture in the combustion chamber 31a in a state where the piston 11 approaches the compression top dead center. Thereby, the piston 11 is driven to rotate the crankshaft 13 in the forward direction.

(4) Engine friction

The friction of the engine 10 varies depending on the state of the engine 10. For example, the lower the engine temperature, the greater the friction of the engine 10. As described above, in the reverse rotation starting operation, when the motor current reaches the threshold (hereinafter referred to as the ignition threshold), the mixed gas in the combustion chamber 31a is ignited. When the ignition threshold is fixed, there is a case where the engine 10 is not properly started during the reverse rotation starting operation due to the frictional fluctuation of the engine 10.

The reverse rotation start operation in the case where the ignition threshold is fixed will be described. Fig. 5 is a view for explaining a case where the engine 10 is appropriately started in the reverse rotation starting operation. Fig. 6 is a view for explaining a state in which the engine 10 is not properly started by the reverse rotation start operation.

In the example of FIG. 5, for example, in the state of restarting from the idle stop state and the engine temperature is relatively high, the reverse rotation start operation is performed. In this case, the friction of the engine 10 is relatively small. On the other hand, in the example of Fig. 6, the reverse rotation start operation is performed, for example, at the time of cold start and the engine temperature is relatively low. In this case, the friction of the engine 10 is relatively large.

In FIGS. 5(a) and 6(a), the horizontal axis represents the crank angle, and the vertical axis represents the rotational load of the crankshaft 13. In FIGS. 5(b) and 6(b), the horizontal axis represents the crank angle and the vertical axis represents the motor current. In FIGS. 5(c) and 6(c), the horizontal axis represents the crank angle, and the vertical axis represents the pressure in the combustion chamber 31a (hereinafter referred to as the in-cylinder pressure).

In the example of Fig. 5(a), the rotational load of the crankshaft 13 changes over a value of V1 or more and a value of V2 or less. When the crank angle is the angle A2 corresponding to the compression top dead center, the rotational load of the crankshaft 13 becomes the maximum value V2. Further, between the angle A1 and the angle A0, the rotational load of the crankshaft 13 is increased by driving the intake valve 15. Also, at angle A0 and angle A3 Between these, the rotational load of the crankshaft 13 becomes large by driving the exhaust valve 16.

As shown in FIG. 5(b), in the reverse rotation starting operation, the motor current becomes a positive value in a state where the crank angle is at the angle A30. Thereby, the crankshaft 13 is driven in the reverse direction by starting the generator 14. When the reverse rotation of the crankshaft 13 is started, the motor current temporarily becomes large, and thereafter the motor current decreases. Thereafter, as the rotational load of the crankshaft 13 increases, the load acting on the starter-generator 14 increases, and the motor current rises. Specifically, the motor current increases between the angle A1 and the angle A0 and between the angle A0 and the angle A3. Further, when the crank angle is close to the angle A2 corresponding to the compression top dead center, the motor current rises. When the motor current reaches the fixed ignition threshold Vt, the mixture in the combustion chamber 31a (FIG. 2) is ignited, and the crankshaft 13 is driven in the forward direction by the start-up generator 14. In this example, when the motor current reaches the ignition threshold Vt, the crank angle is the angle A31.

As shown in Fig. 5(c), when the crank angle reaches the angle A31, the in-cylinder pressure becomes the value Ps. In this state, the mixed gas is ignited to burn the mixed gas. In this example, sufficient energy is obtained by combustion of the mixture. Thereby, as shown in FIG. 5(a), the crankshaft 13 can exceed the angle A2 corresponding to the initial compression top dead center.

The difference from the example of Fig. 5 will be described with respect to the example of Fig. 6. In the example of Fig. 6, the friction of the engine 10 is larger than that of the example of Fig. 5. Therefore, as shown in FIG. 6(a), the rotational load of the crankshaft 13 changes within a range of a value V3 or more and a value of V4 or less. The value V3 is greater than the value V1 and the value V4 is greater than the value V2.

Thereby, the load acting on the starter-generator 14 (FIG. 2) becomes large in the entire range of the crank angle. Therefore, as shown in FIG. 6(b), the motor current is larger than the example of FIG. 5(b) in the entire range of the crank angle.

When the motor current reaches the fixed ignition threshold Vt, the mixture in the combustion chamber 31a (Fig. 2) is ignited, and the crankshaft 13 is driven in the forward direction by the start-up generator 14. In this example, when the motor current reaches the ignition threshold Vt, the crank angle is the angle A31s. The angle A31s is located in the opposite direction at the angle A31 near the advance side.

The pressure in the cylinder depends on the crank angle. As shown in Fig. 6(c), when the crank angle reaches the angle A31s, the in-cylinder pressure becomes the value Psa. The value Psa is less than the value Ps. In this state, the mixed gas in the combustion chamber 31a is ignited to burn the mixed gas. The lower the in-cylinder pressure at the time of ignition of the mixed gas, the smaller the energy obtained by the combustion of the mixed gas. In this case, sufficient energy cannot be obtained by the combustion of the mixture. Therefore, as shown in Fig. 6(a), the crankshaft 13 cannot exceed the angle A2 corresponding to the initial compression top dead center.

Thus, if the friction of the engine 10 is different, the relationship between the motor current and the in-cylinder pressure is different. Therefore, when the ignition threshold value is fixed, the in-cylinder pressure at the time of ignition of the mixed gas is uneven due to the frictional fluctuation of the engine 10.

As an example of Fig. 6, when the mixture in the combustion chamber 31a is ignited in a state where the in-cylinder pressure is not sufficiently increased, sufficient energy for rotating the crankshaft 13 in the forward direction cannot be obtained. Thereby, the engine 10 cannot be properly started.

(5) Setting of ignition threshold

In order to obtain sufficient energy by combustion of the mixed gas, the in-cylinder pressure at the time of ignition of the mixed gas must be adjusted with high precision. Therefore, in the present embodiment, the ignition threshold value is appropriately set in accordance with the friction of the engine 10.

For example, a map indicating the relationship between the engine temperature and the ignition threshold (hereinafter referred to as a threshold setting map) is stored in the memory of the ECU 6 of FIG. The threshold setting mapping table is obtained by experiment or simulation or the like. Fig. 7 is a view showing an example of a threshold setting map. In FIG. 7, the horizontal axis represents the engine temperature, and the vertical axis represents the ignition threshold.

As shown in FIG. 7, in the threshold setting map, the relationship between the engine temperature and the ignition threshold is defined such that the ignition threshold becomes smaller as the engine temperature becomes higher. The ECU 6 sets an ignition threshold corresponding to the engine temperature based on the threshold setting map. As mentioned above, there is a correlation between engine temperature and friction of the engine 10. Therefore, the greater the friction of the engine 10, the larger the set ignition threshold becomes. In this case, even if the friction of the engine 10 is different, the ignition threshold can be adjusted so that the crank angle at the time of ignition of the mixed gas is fixed. Take Next, the target value of the crank angle at which the mixture should be ignited is referred to as the target angle. In this example, the target angle is angle A31.

Fig. 8 is a schematic view for explaining setting of an ignition threshold. Similarly to Figs. 5(a) to 5(c) and Figs. 6(a) to 6(c), in Figs. 8(a) to 8(c), the horizontal axis represents the crank angle and the vertical axis represents Indicates the rotary load, motor current, and in-cylinder pressure.

In the example of Fig. 8, the friction of the engine 10 is the same as that of Fig. 6. Therefore, as shown in FIG. 8(a), the rotational load of the crankshaft 13 changes within a range of a value V3 or more and a value of V4 or less. The example of Fig. 8 differs from the example of Fig. 6 in the following aspects.

As shown in Fig. 8(b), the ignition threshold is set to Vta. The value Vta is greater than the value Vt. In this case, when the motor current reaches the ignition threshold Vta, the crank angle is the angle A31. When the motor current reaches the ignition threshold Vta, the mixture in the combustion chamber 31a is ignited, and the crankshaft 13 is driven in the forward direction by the start-up generator 14.

As shown in Fig. 8(c), when the crank angle reaches the angle A31, the in-cylinder pressure becomes the value Ps. In this state, the mixed gas in the combustion chamber 31a is ignited to burn the mixed gas. Thereby, as in the example of FIG. 5, sufficient energy can be obtained by combustion of the mixed gas. Therefore, as shown in Fig. 8(a), the crank angle may exceed the angle A2 corresponding to the initial compression top dead center.

(6) drive duty cycle ratio

The torque generated by starting the generator 14 depends on the duty cycle ratio of the current supplied to the starter-generator 14 (hereinafter referred to as the drive duty ratio). In the reverse rotation start operation, if the drive duty cycle is relatively low, there is a possibility that the crank angle cannot reach the target angle. In particular, as in the case of FIG. 6, in the case where the friction of the engine 10 is large, there is a possibility that the reverse rotation of the crankshaft 13 is stopped by the rotational load of the crankshaft 13 before the crank angle reaches the target angle. .

On the other hand, if the driving duty cycle is relatively high, it is easy to make the crank angle reach the target angle, but there is a possibility that the power is excessively consumed. In particular, as in the example of Figure 5, in the engine When the friction of 10 is small, even if the torque generated by starting the generator 14 is small, the crank angle can be made to reach the target angle. Therefore, if the drive duty cycle is relatively high, power is excessively consumed.

Therefore, the drive duty ratio can also be adjusted in a manner corresponding to the friction of the engine 10. For example, the memory of the ECU 6 of FIG. 2 stores a map indicating the relationship between the engine temperature and the drive duty ratio (hereinafter referred to as a drive duty ratio setting map). The drive duty cycle ratio setting map can be obtained by experiment or simulation or the like. Fig. 9 is a view showing an example of a drive duty ratio setting map. In Fig. 9, the horizontal axis represents the engine temperature, and the vertical axis represents the drive duty cycle ratio.

As shown in FIG. 9, in the drive duty cycle ratio setting map, the relationship between the engine temperature and the drive duty cycle is defined in such a manner that the drive duty cycle ratio becomes lower as the engine temperature becomes higher. The ECU 6 sets a drive duty ratio corresponding to the engine temperature based on the drive duty cycle ratio map. In this case, the greater the friction of the engine 10, the higher the drive duty cycle ratio is set.

In this manner, the drive duty cycle ratio is adjusted in a manner corresponding to the friction of the engine 10, whereby excessive power consumption can be prevented, and the crank angle can be adjusted to the target angle.

(7) Adjustment of target angle

If the friction of the engine 10 is different, the torque for making the crank angle exceed the positive direction of the crankshaft 13 required for the angle A2 corresponding to the initial compression top dead center is different. The smaller the friction of the engine 10, the smaller the torque in the positive direction of the crankshaft 13 required.

As described above, the torque in the positive direction of the crankshaft 13 obtained by the reverse rotation start-up action depends on the in-cylinder pressure at the time of ignition of the mixed gas, and the in-cylinder pressure depends on the crank angle. Therefore, the target angle can also be adjusted in a manner corresponding to the friction of the engine 10.

The crank angle at the time of ignition of the mixed gas can also be adjusted by adjusting the ignition threshold. In the threshold setting map of FIG. 7, even if the friction of the engine 10 is different, the relationship between the engine temperature and the ignition threshold can be specified so that the target angle is fixed. Can also be replaced On the other hand, the relationship between the engine temperature and the ignition threshold is set such that the smaller the friction of the engine 10 is, the more the target angle is away from the angle A2.

Fig. 10 is a schematic view for explaining adjustment of a target angle. Similarly to Figs. 5(a) to 5(c) and Figs. 6(a) to 6(c), in Figs. 10(a) to 10(c), the horizontal axis represents the crank angle and the vertical axis represents Indicates the rotary load, motor current, and in-cylinder pressure.

Regarding the example of Fig. 10, a difference from the example of Fig. 5 will be described. In the example of Figure 10, the friction of the engine 10 is less than that of Figure 5. Therefore, as shown in FIG. 10(a), the rotational load of the crankshaft 13 changes within a range of a value V5 or more and a value V6 or less. The value V5 is less than the value V1 and the value V6 is less than the value V2.

Further, as shown in FIG. 10(b), the motor current is smaller than the example of FIG. 5(b) in the entire range of the crank angle. The ignition threshold is set to Vtb. The value Vtb is smaller than the value Vt. In this case, when the motor current reaches the ignition threshold Vtb, the crank angle is the angle A31t. In this example, the angle A31t is the target angle, and the opposite angle A31 is located near the advance angle side in the reverse direction. When the motor current reaches the ignition threshold Vtb, the mixture in the combustion chamber 31a is ignited, and the crankshaft 13 is driven in the forward direction by the start-up generator 14.

As shown in Fig. 10(c), when the crank angle reaches the angle A31t, the in-cylinder pressure becomes the value Psb. The value Psb is smaller than the value Ps. In this state, the mixed gas in the combustion chamber 31a is ignited to burn the mixed gas. In this case, since the friction of the engine 10 is small, even if the energy obtained by the combustion of the mixed gas is small as compared with the example of Fig. 5, the crankshaft 13 can exceed the angle A2 corresponding to the initial compression top dead center.

In this manner, the target angle is adjusted in accordance with the friction of the engine 10, whereby the power consumed by the start-up generator 14 can be reduced while the reverse rotation start-up operation is performed, and the desired positive direction of the crankshaft 13 can be obtained. Torque.

Further, ignition control may be performed based on the crank angle instead of the ignition control based on the motor current. Specifically, when the crank angle obtained from the detection results of the intake pressure sensor 42 (FIG. 2) and the crank angle sensor 43 (FIG. 2) reaches the target angle, the combustion is also performed. The mixture in the chamber 31a is ignited.

Further, ignition control based on motor current and ignition control based on crank angle may be combined. For example, the ignition threshold and the target angle may be respectively set in accordance with the friction of the engine 10 to satisfy the ignition threshold detected by the current sensor 44, or by the intake pressure sensor. When the crank angle detected by the crank angle sensor 43 reaches any of the target angles, the mixture in the combustion chamber 31a is ignited.

(8) Engine startup processing

The ECU 6 performs an engine start process based on a control program previously stored in the pre-memory. Figure 11 is a flow chart of the engine startup process. For example, the engine start processing is performed when the main switch 40 of Fig. 2 is turned on, or when the engine 10 is moved to the idle stop state.

As shown in Fig. 11, the ECU 6 determines whether or not the predetermined start condition is satisfied (step S1). In the case where the engine unit EU is not in the idle stop state, the starting condition is, for example, the start switch 41 (FIG. 2). When the engine unit EU is in the idle stop state, the starting condition is that the idle stop release condition is satisfied.

When the start condition is not satisfied, the ECU 6 repeats the process of step S1 until the start condition is satisfied. When the start condition is satisfied, the ECU 6 performs parameter setting processing (step S2). The ignition threshold and the drive duty ratio are set by parameter setting processing. The details of the parameter setting process are described below. Then, the ECU 6 controls the starter-generator 14 so that the crankshaft 13 rotates in the reverse direction (step S3). In this case, the starter-generator 14 is controlled by the drive duty cycle ratio set by the parameter setting process.

Furthermore, at the start of the engine start processing, when the crank angle is not in the reverse rotation start range (angle A30), as described above, the crank angle can also be adjusted to the reverse direction before the crank shaft 13 is reversely rotated. Rotation start range.

Next, the ECU 6 determines whether or not the fuel injection condition is satisfied (step S4). For example, the fuel injection conditions are detected from the intake pressure sensor 42 (Fig. 2) and the crank angle sensor 43 (Fig. 2). As a result, the crank angle obtained reaches the angle A23 of FIG. When the fuel injection condition is not satisfied, the ECU 6 repeats the processing of step S3. If the fuel injection condition is satisfied, the ECU 6 controls the injector 19 (FIG. 2) in such a manner as to inject the fuel into the intake passage 22 (FIG. 2) (step S5). In this case, the ECU 6 can also control the injector 19 in response to a pulse signal from the crank angle sensor 43.

Next, the ECU 6 determines whether or not the energization start condition is satisfied (step S6). For example, the energization start condition is that the crank angle obtained from the detection results of the intake pressure sensor 42 (FIG. 2) and the crank angle sensor 43 (FIG. 2) reaches the angle A31a of FIG. When the energization start condition is not satisfied, the ECU 6 repeats the processing of step S6. When the energization start condition is satisfied, the ECU 6 starts energization of the ignition coil (step S7). In this case, the ECU 6 can also control the ignition coil in response to the pulse signal from the crank angle sensor 43.

Next, the ECU 6 determines whether or not the ignition condition is satisfied (step S8). In this example, the ignition condition is that the motor current detected by the current sensor 44 (Fig. 2) reaches the ignition threshold set in the parameter setting process of step S2.

When the ignition condition is not satisfied, the ECU 6 repeats the processing of step S8. When the ignition condition is satisfied, the ECU 6 controls the starter-generator 14 so that the crankshaft 13 rotates in the forward direction (step S9), and controls the spark plug 18 in such a manner as to ignite the mixture in the combustion chamber 31a (step S10). ). Thereby, the engine startup process is ended.

The parameter setting process of step S2 will be described. Figure 12 is a flow chart of the parameter setting process. As shown in FIG. 12, the ECU 6 acquires the engine temperature detected by the temperature sensor 45 (step S11).

Next, the ECU 6 sets an ignition threshold based on the acquired engine temperature (step S12). For example, the ignition threshold corresponding to the acquired engine temperature is acquired from the threshold setting map of FIG. In this case, as shown in FIG. 8, the ignition threshold may be set such that the target angle is fixed, or the ignition threshold may be set differently as the target angle as in the case of FIG.

Next, the ECU 6 sets the drive duty ratio based on the acquired engine temperature (step S13). For example, the driving duty cycle from the driving duty cycle of FIG. 9 is higher than the setting mapping table to obtain the driving duty cycle corresponding to the acquired engine temperature. The parameter setting process is ended by setting the ignition threshold and the drive duty cycle ratio in this manner.

(9) effect

In the engine system 200 of the present embodiment, when the engine 10 is started, the mixture is introduced into the combustion chamber 31a while the crankshaft 13 is rotated in the reverse direction, and the mixture in the combustion chamber 31a is mixed when the motor current reaches the ignition threshold. Gas is ignited. In this case, since the ignition threshold is set based on the engine temperature corresponding to the friction of the engine 10, the mixture in the combustion chamber 31a is ignited when the in-cylinder pressure is an appropriate value corresponding to the friction of the engine 10. Therefore, sufficient energy for driving the crankshaft 13 in the positive direction can be obtained by the combustion of the mixed gas. As a result, the engine 10 can be appropriately started up.

Further, since the ignition temperature is controlled by the engine temperature detected by the temperature sensor 45 and the motor current detected by the current sensor 44, it is possible to perform the friction with the engine 10 while suppressing the complication of the configuration. Proper control.

(10) Other embodiments

In the above embodiment, the engine temperature is used as a parameter corresponding to the friction of the engine 10. However, the present invention is not limited thereto, and other parameters corresponding to the friction of the engine 10 may be used. For example, the rotational load of the crankshaft 13 can also be detected, and the detected value can be used as a parameter corresponding to the friction of the engine 10.

Further, in the above embodiment, the motor current and the crank angle are used as parameters corresponding to the in-cylinder pressure, but the present invention is not limited thereto, and other parameters corresponding to the in-cylinder pressure may be used. For example, a pressure sensor that detects the pressure in the cylinder may be provided, and the detected value is used as a parameter corresponding to the in-cylinder pressure.

Further, a value (for example, a rate of change or a change amount) indicating a change in the rotational speed of the crankshaft 13 may be used as a parameter corresponding to the in-cylinder pressure. For example, based on the angle from the crank The amount of change in the rotational speed of the crankshaft 13 per unit time (hereinafter referred to as the amount of change in rotation) is calculated by the detection signal of the sensor 43. The amount of change in rotation depends on the in-cylinder pressure, and as the in-cylinder pressure becomes larger, the amount of change in rotation becomes larger. Therefore, in the reverse rotation start operation, for example, the threshold value of the rotational change amount may be set as the ignition threshold value based on the engine temperature detected by the temperature sensor 45, and the combustion may be performed when the rotational change amount reaches the set threshold value. The mixture in the chamber 31a is ignited. As a result, similarly to the above-described embodiment, it is possible to suppress the complication of the configuration and to perform appropriate control corresponding to the friction of the engine 10.

The above embodiment is an example in which the present invention is applied to a locomotive, but the present invention is not limited thereto, and the present invention can also be applied to other straddle-type vehicles such as a three-wheeled vehicle or an ATV (All Terrain Vehicle).

(11) Correspondence between each component of the request item and each element of the embodiment

Hereinafter, an example in which each component of the request item corresponds to each element of the embodiment will be described, but the present invention is not limited to the following examples.

In the above embodiment, the engine system 200 is an example of an engine system, the engine unit EU is an example of an engine unit, the engine 10 is an example of an engine, the start-up generator 14 is an example of a rotary drive unit, and the temperature sensor 45 is friction. In the example of the detecting unit, the current sensor 44 is an example of a pressure detecting unit, the ECU 6 is an example of a control unit, the injector 19 is an example of a fuel injection device, the spark plug 18 is an ignition device, and the valve driving unit 17 is a valve driving unit. An example of the Ministry. Moreover, the locomotive 100 is an example of a straddle type vehicle, the vehicle body 1 is an example of a main body portion, and the rear wheel 7 is an example of a drive wheel.

As each component of the request item, various other elements having the configuration or function described in the request item can be used.

[Industrial availability]

The present invention can be effectively applied to various engine systems and straddle-type vehicles.

A0‧‧‧ angle

A1‧‧‧ angle

A2‧‧‧ angle

A3‧‧‧ angle

A30‧‧‧ angle

A31‧‧‧ angle

A31s‧‧‧ angle

Ps‧‧ value

Psa‧‧ value

V3‧‧‧ value

V4‧‧‧ value

Vt‧‧‧Ignition threshold

Vta‧‧‧Ignition threshold

Claims (7)

An engine system includes: an engine unit including an engine and a rotary drive unit; a friction detecting unit that detects a first parameter corresponding to friction of the engine; and a pressure detecting unit that detects a pressure corresponding to a pressure in a combustion chamber of the engine a second parameter; and a control unit that controls the engine unit based on a first parameter detected by the friction detecting unit and a second parameter detected by the pressure detecting unit; and the engine includes: a fuel injection device And arranging the fuel to be injected into the intake passage of the combustion chamber; the ignition device is configured to ignite the mixture in the combustion chamber; and the valve drive unit The air intake valve is 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 the rotary drive unit rotates the crankshaft in a forward direction and a reverse direction. According to another aspect of the invention, the control unit controls the engine unit to perform the reverse rotation start operation when the engine is started. In the starting operation, the mixture is introduced into the combustion chamber while rotating the crankshaft in the reverse direction, and the mixture is ignited so that the crankshaft is driven in the forward direction, and the control unit is activated in the reverse rotation. In the operation, the ignition threshold is set based on the first parameter detected by the friction detecting unit, and when the second parameter detected by the pressure detecting unit reaches the set ignition threshold. The ignition method described above controls the ignition device. The engine system of claim 1, wherein the first parameter is a value corresponding to a temperature of the engine. The engine system of claim 1 or 2, wherein the second parameter is a current flowing to the rotary drive unit. The engine system of claim 1 or 2, wherein the second parameter is the crank angle of the engine. The engine system of claim 1 or 2, wherein the second parameter is a value indicating a change in a rotational speed of the crankshaft. The engine system according to claim 1 or 2, wherein the control unit adjusts a torque generated by the rotation driving unit based on a first parameter detected by the friction detecting unit during the reverse rotation starting operation. A straddle-type vehicle comprising: a body portion having a drive wheel; and an engine system according to claim 1 or 2, which generates power for rotating the drive wheel.