Idle stop control device

Abstract

The engine control unit (78) of the motorcycle (10) includes an engine control unit (140) and a starter motor control unit (142). The engine control unit stops the engine (42) when the idle stop condition is met. The starter motor control unit controls the ACG starter motor (44) to output a torque that rotates the crankshaft (52) when the idle stop condition is met. The starter motor control unit (142) sets the torque output by the ACG starter motor (44) according to the speed of the engine (42) when the idle stop condition is met.

Description

Technical Field

[0001] This invention relates to an idle stop control device. Background Technology

[0002] Japanese Patent Publication No. 2020-165343 discloses an engine starting control device for a two-wheeled motor vehicle. This engine starting control device stops the engine from idling when a predetermined idling stop condition is met. Furthermore, when a restart condition is met after idling stop, the engine restarts. Before restarting the engine, the crankshaft is oscillated by the starter motor. Then, the crankshaft is rotated forward by the starter motor, thereby restarting the engine. Oscillating means that the crankshaft is rotated in the reverse direction by the starter motor. By oscillating the crankshaft, the rotation angle of the crankshaft in the forward rotation direction can be deviated from the rotation angle corresponding to the top dead center of the piston. Therefore, when the starter motor rotates the crankshaft, the travel distance can be ensured until the rotation angle corresponding to the compression top dead center of the piston is reached. Thus, the starter motor can powerfully rotate the crankshaft. As a result, the time required for engine restart can be shortened. Summary of the Invention

[0003] In the engine start control device disclosed in Japanese Patent Publication No. 2020-165343, the crankshaft requires time to return to its original position after the engine restart conditions are met. Therefore, the technical problem is that time is required from the time the engine restart conditions are met until the engine restarts.

[0004] The purpose of this invention is to solve the above-mentioned technical problems.

[0005] The present invention relates to an idle stop control device for a motorcycle-type vehicle, having an engine and a starter motor, wherein the starter motor outputs a torque to the crankshaft of the engine to rotate the crankshaft.

[0006] In this case, the first structure includes a condition determination unit, an engine control unit, and a starter motor control unit. The condition determination unit determines that the idle stop condition of the engine is met. The engine control unit stops the engine when the idle stop condition is met. The starter motor control unit controls the starter motor to output the torque that rotates the crankshaft when the idle stop condition is met. The starter motor control unit sets the torque output by the starter motor based on the engine speed when the idle stop condition is met.

[0007] As a second structure, the starter motor control unit sets the torque output by the starter motor based on the engine speed when the idle stop condition is met and the crankshaft rotation angle after the idle stop condition is met.

[0008] As a third structure, during the period when the engine stops after the idle stop condition is met, the starter motor control unit sets the torque output by the starter motor to be larger as the rotation angle of the crankshaft gets closer to the rotation angle corresponding to the top dead center of the piston of the engine.

[0009] As a fourth structure, the starter motor control unit sets the torque output by the starter motor to be greater as the engine speed decreases.

[0010] According to the first structure, after idling stops, the time required from the time the engine restart conditions are met until the engine starts can be shortened.

[0011] According to structures 2 to 4, before the engine stops, the crankshaft can be rotated to a rotation angle exceeding the rotation angle corresponding to the piston's compression top dead center. Attached Figure Description

[0012] Figure 1 This is a side view of a straddle-type vehicle. Figure 2 This is a cross-sectional view of the swing unit. Figure 3 This is a control block diagram of the engine control unit. Figure 4 It is a duty cycle mapping diagram. Detailed Implementation

[0013] [First Embodiment] [Structure of a motorcycle-type vehicle] Figure 1 This is a side view of the straddle-type vehicle 10. In the following description, based on... Figure 1 The arrows indicate the directions: front, back, up, and down. Additionally, when the driver is seated facing forward on the straddle-type vehicle 10, the driver's left side is designated as "left," and the driver's right side as "right."

[0014] The straddle-type vehicle 10 in this embodiment is a scooter-type two-wheeled motor vehicle. The straddle-type vehicle 10 can be a motorcycle other than a scooter. In addition, the straddle-type vehicle 10 can also be a three-wheeled motor vehicle, a four-wheeled motor vehicle, etc.

[0015] The motorcycle 10 of this embodiment is equipped with an idle stop function. The idle stop function is a function that automatically stops the engine 42 when predetermined conditions are met while the motorcycle 10 is parked. The idle stop function also includes a function that automatically restarts the engine 42 after it has been stopped. Idle stop is sometimes referred to as idle stop, idle speed reduction, no idle, start-stop, etc.

[0016] The motorcycle 10 has a frame 12. The frame 12 has a head tube 14, a down frame 16, a subframe 18 and a rear frame 20.

[0017] The head tube 14 extends forward and downward. The downframe 16 extends backward and downward from the head tube 14. The downframe 18 branches to the left and right from the lower end of the downframe 16. The downframes 18 that branch to the left and right extend backward. The rear frames 20 extend backward and upward from the rear ends of the left and right downframes 18 respectively.

[0018] The motorcycle 10 has a steering system 21. The steering system 21 includes a steering column 22, a bottom beam 24, a front fork 26, and a handlebar 30.

[0019] The steering column 22 is inserted into the head tube 14. The head tube 14 rotatably supports the steering column 22. A front fork 26 is connected to the lower end of the steering column 22 via a bottom beam 24. The front fork 26 is split to the left and right at its upper end. The split front fork 26 extends forward and downward. A front wheel 28 is mounted at the lower end of the front fork 26. The front wheel 28 is rotatably supported on both sides of the left and right front forks 26.

[0020] A steering handle 30 is mounted on the upper end of the steering column 22. The driver steers the front wheels 28 by maneuvering the steering handle 30. A grip 32 is mounted on the left end of the steering handle 30. A throttle grip 34 is mounted on the right end of the steering handle 30. By rotating the throttle grip 34, the driver can adjust the opening of the throttle valve.

[0021] Rear suspensions 36 are mounted on the left and right rear frames 20 respectively. The rear suspensions 36 extend rearward and downward. A rear wheel 54 is mounted on the top part of the rear suspension 36. The rear wheel 54 is rotatably supported by the rear suspension 36.

[0022] A swing unit 40 is connected to the rear end of the lower frame 18 via a linkage mechanism 38. The swing unit 40 includes an engine 42, an ACG (AC Generator) starter motor 44, a continuously variable transmission 46, an air filter 48, and a fuel injection device 50.

[0023] Engine 42 is a single-cylinder, four-stroke engine. Engine 42 has a crankshaft 52 that causes a piston (not shown) to reciprocate within a cylinder (not shown). Figure 2 The ACG starter motor 44 rotates the crankshaft 52 when the engine 42 is started. After the engine 42 is started, the ACG starter motor 44 acts as an alternator to generate electricity.

[0024] A continuously variable transmission (CVT) 46 is disposed between the engine 42 and the rear wheel 54. The CVT 46 is connected to the rear wheel 54 via a reducer 56 having a centrifugal clutch (not shown).

[0025] Air filter 48 is connected to engine 42 via intake manifold 58. Fuel injection device 50 is disposed in intake manifold 58. Fuel injection device 50 injects fuel into the interior of intake manifold 58.

[0026] The frame 12 is covered by a body cover 60 made of synthetic resin. The body cover 60 has a front cover 62, a front fender 64, a handlebar cover 66, a leg guard 68, a lower cover 70, side covers 72 and a rear fender 74.

[0027] The front cover 62 covers the front and rear of the head tube 14. A main switch 76 is installed on the front cover 62. The driver can switch the main switch 76 on and off by operating it. An engine control unit 78 is located inside the front cover 62. The front fender 64 covers the top and rear of the front wheel 28.

[0028] The handlebar cover 66 covers the central portion of the handlebars 30 and the steering column 22 in the width direction. A start switch 80 is installed on the handlebar cover 66. With the main switch 76 activated, the driver starts the engine 42 by operating the start switch 80. Leg guards 68 cover the underframe 16 and the area in front of the driver's legs. Lower covers 70 cover the top of the left and right lower frames 18. Lower covers 70 have foot pedals 82. Side covers 72 cover the outer sides of the left and right rear frames 20. A seat 84 is installed on the upper part of the side covers 72. A rear fender 74 covers the top of the rear wheel 54.

[0029] [Structure of the oscillating unit] Figure 2 This is a cross-sectional view of the swing unit 40. Figure 2 The swing unit 40 is represented by Figure 1 The cross-section is formed by cutting from II-II. The swing unit 40 has a crankcase 86. The crankcase 86 has a left housing 88 and a right housing 90.

[0030] The crankshaft 52 is rotatably supported by bearings 92 and 94 disposed in the crankcase 86. A connecting rod 98 is connected to the crankshaft 52 via a crank pin 96.

[0031] The left housing 88 also serves as the transmission housing for the continuously variable transmission (CVT) 46. A drive pulley 100 is mounted on the left end of the crankshaft 52. The drive pulley 100 has a fixed pulley 102 and a movable pulley 104. The fixed pulley 102 is fixed to the left end of the crankshaft 52 by a nut 103. The movable pulley 104 is splined into the crankshaft 52. The movable pulley 104 is movable along the rotation axis of the crankshaft 52. A belt 106 is clamped between the fixed pulley 102 and the movable pulley 104.

[0032] On the right side of the movable pulley 104, a swashplate 107 is fixed to the crankshaft 52. A sliding member 109 is mounted on the outer periphery of the swashplate 107. A protrusion 111 is formed on the outer periphery of the movable pulley 104. The protrusion 111 extends to the right from the movable pulley 104. The sliding member 109 engages with the protrusion 111. A conical surface 113 is formed on the outer periphery of the swashplate 107. The conical surface 113 is shaped to slope towards the movable pulley 104 as it moves from the inner periphery to the outer periphery of the swashplate 107. A plurality of counterweight rollers 115 are disposed between the conical surface 113 and the movable pulley 104.

[0033] As the rotational speed of crankshaft 52 increases, the counterweight roller 115 moves towards the outer periphery of inclined plate 107 due to centrifugal force. This causes the counterweight roller 115 to push against movable pulley 104, bringing it closer to fixed pulley 102. Consequently, the belt 106, held by fixed pulley 102 and movable pulley 104, moves towards the outer periphery of drive pulley 100. Therefore, the winding diameter of belt 106 relative to drive pulley 100 increases.

[0034] The torque input from engine 42 to drive pulley 100 is transmitted to driven pulley (not shown) via belt 106. The torque transmitted to driven pulley is then transmitted to rear wheel 54 via reducer 56.

[0035] An ACG starter motor 44 is disposed inside the right housing 90. The ACG starter motor 44 is a three-phase brushless motor. The ACG starter motor 44 has a rotor 108 and a stator 110.

[0036] The rotor 108 is fixed to the top of the crankshaft 52 by bolts 112. The rotor 108 rotates integrally with the crankshaft 52. The rotor 108 has a plurality of magnets 114. The plurality of magnets 114 are arranged circumferentially along the rotor 108.

[0037] The stator 110 is disposed on the inner circumference of the rotor 108. The stator 110 is fixed to the right housing 90 by bolts 116. Coils 118 corresponding to the U phase, V phase and W phase are wound on the stator 110 respectively.

[0038] A fan 120 is mounted on the rotor 108. The fan 120 is fixed to the rotor 108 by bolts 122. An outer casing 124 is mounted on the right side of the fan 120. The outer casing 124 has a heat sink 126.

[0039] A sprocket 128 is fixed on the crankshaft 52. The sprocket 128 is positioned between the ACG starter motor 44 and the bearing 94. A cam chain (not shown) for driving the camshaft (not shown) is wound around the sprocket 128. The sprocket 128 is integrally formed with the pump gear 130. The pump gear 130 transmits the torque of the crankshaft 52 to the pump (not shown). The pump discharges oil used to lubricate the engine 42, etc.

[0040] [Structure of the engine control unit] Figure 3 This is a control block diagram of the engine control device 78. The engine control device 78 includes a drive circuit 132, a voltage regulator 134, and an arithmetic unit 136. The engine control device 78 corresponds to the idle speed stop control device of the present invention.

[0041] The drive circuit 132 functions as either an inverter or a converter. When the ACG starter motor 44 is powered by battery electricity, the drive circuit 132 functions as an inverter. When the ACG starter motor 44 regenerates to charge the battery, the drive circuit 132 functions as a converter. When the drive circuit 132 functions as an inverter, it adjusts the voltage output to the ACG starter motor 44 via PWM control. This controls the torque output by the ACG starter motor 44.

[0042] The voltage regulator 134 adjusts the voltage output from the drive circuit 132 to a specified voltage to charge the battery.

[0043] The arithmetic unit 136 is implemented by a processing circuit. This processing circuit may be constructed from integrated circuits such as ASICs (Application Specific Integrated Circuits) or FPGAs (Field-Programmable Gate Arrays). Alternatively, the processing circuit may be constructed from electronic circuits containing discrete components. Furthermore, the processing circuit may also be constructed from processors such as CPUs (Central Processing Units) or GPUs (Graphics Processing Units). In this case, the processing circuit is implemented by the processor executing a program stored in a memory unit (not shown).

[0044] The arithmetic unit 136 includes a condition determination unit 138, an engine control unit 140, and a starter motor control unit 142.

[0045] When the engine 42 is driven, the condition determination unit 138 determines that the idle stop condition of the engine 42 is met. The idle stop condition refers to, for example, the conditions (1) to (3) below.

[0046] (1) The speed of the motorcycle 10 is below the prescribed speed. (2) The driver's braking operation amount is above the prescribed operation amount. (3) The battery's SOC (State of Charge) is above the specified value. As an idle stop condition, it may also have conditions other than those mentioned in (1) to (3).

[0047] Furthermore, the condition determination unit 138 determines that the restart condition of the engine 42 is met after the engine 42 stops idling. The restart condition of the engine 42 refers to, for example, the following (4) to (6).

[0048] (4) The driver's braking operation amount is less than the specified operation amount. (5) The rotation angle of the throttle lever 34 is above the specified rotation angle. (6) The SOC of the battery is less than the specified value. As a restart condition for engine 42, conditions other than those mentioned in (4) to (6) can also be present.

[0049] When the idling stop condition is met, the engine control unit 140 controls the fuel injection device 50 to stop fuel injection. After the fuel injection device 50 stops fuel injection, the crankshaft 52 initially continues to rotate due to inertia. Then, the engine 42 stops.

[0050] When the idle stop condition is met, the starter motor control unit 142 controls the drive circuit 132, causing the ACG starter motor 44 to output torque that rotates the crankshaft 52 forward. The starter motor control unit 142 sets the duty cycle of the PWM (Pulse Width Modulation) control of the drive circuit 132 based on the engine speed 42. The starter motor control unit 142 sets the duty cycle based on the rotation angle of the crankshaft 52 until the engine 42 stops. This controls the torque output by the ACG starter motor 44.

[0051] After the fuel injection device 50 stops fuel injection, the ACG starter motor 44 assists the crankshaft 52 in rotating due to inertia. Due to the assistance of the ACG starter motor 44, the crankshaft 52 can rotate to an angle exceeding the rotational angle corresponding to the piston's top dead center during compression before the engine 42 stops. As a result, the rotational angle of the crankshaft 52 when the engine 42 stops is an angle exceeding the rotational angle corresponding to the piston's top dead center during compression. The control of the torque output by the ACG starter motor 44 when the idle stop condition is met will be explained in detail later.

[0052] When the restart condition of engine 42 is met, the starter motor control unit 142 controls the drive circuit 132 to cause the ACG starter motor 44 to output torque that rotates the crankshaft 52. When the idle stop condition is met, the engine control unit 140 controls the fuel injection device 50 to start fuel injection. Thus, engine 42 restarts.

[0053] [Regarding torque control of the ACG starter motor] Figure 4 It is a duty cycle mapping diagram. Figure 4 The mapping diagram is used for PWM control of drive circuit 132 when the idle stop condition is met. Figure 4 The duty cycle corresponding to the combination of engine speed 42 and crankshaft rotation angle 52 is shown. The higher the duty cycle of the PWM control of drive circuit 132, the greater the torque output of ACG starter motor 44.

[0054] The engine speed of 42 used to determine the duty cycle according to the mapping diagram is the speed at the point when the idle stop condition is met. After the idle stop condition is met, the engine speed of 42 at the point when the fuel injection device 50 stops fuel injection can also be used.

[0055] The crankshaft 52 rotation angle used to determine the duty cycle from the time the idle stop condition is met until the time the engine 42 stops. The crankshaft 52 rotation angle changes continuously during this period. The duty cycle change is determined from the mapping diagram based on the change in the crankshaft 52 rotation angle. Alternatively, the crankshaft 52 rotation angle used to determine the duty cycle from the time the fuel injection device 50 stops injecting fuel until the time the engine 42 stops, assuming the idle stop condition is met.

[0056] exist Figure 4 In the mapping diagram shown, the rotation angle of the crankshaft 52 corresponding to the top dead center of the piston exhaust is set to 360 degrees. Figure 4In the mapping diagram shown, the rotation angle of the crankshaft 52 corresponding to the top dead center of the piston compression is set to 720 degrees.

[0057] like Figure 4 As shown, the lower the engine speed of 42, the higher the duty cycle is set. Consequently, the lower the engine speed of 42, the greater the torque output of the ACG starter motor 44 is set.

[0058] like Figure 4 As shown, when the engine speed of 42 is low, the duty cycle is increased starting from when the crankshaft 52's rotation angle is small. Figure 4 As shown, when the engine speed 42 is 100 rpm to 300 rpm and the crankshaft 52 rotates at an angle of 10 degrees to 360 degrees, the duty cycle is set to 10% to 30%. As a result, the ACG starter motor 44 can output torque to a degree that allows the ACG starter motor 44 to run continuously.

[0059] [Effects] There has always been a technique that allows the crankshaft 52 to swing back when the restart conditions of the engine 42 are met after idling stop. This allows the rotation angle of the crankshaft 52 to deviate from the rotation angle corresponding to the top dead center of the piston in the forward rotation direction. Therefore, the ACG starter motor 44 can forcefully rotate the crankshaft 52. As a result, the restart time required for the engine 42 can be shortened.

[0060] However, once the restart conditions for engine 42 are met, time is required for crankshaft 52 to return to its original position. Therefore, time is required from the time the restart conditions for engine 42 are met until engine 42 restarts.

[0061] In the engine control device 78 of this embodiment, when the idle stop control is established, the starter motor control unit 142 controls the ACG starter motor 44 to output torque that causes the crankshaft 52 to rotate forward. The starter motor control unit 142 sets the torque output by the ACG starter motor 44 based on the engine speed of the engine 42 at the time when the idle stop condition is established.

[0062] During the compression cycle of engine 42, the closer crankshaft 52 is to the rotational angle corresponding to the piston's top dead center (TDC), the more compressed the air in the cylinder becomes, thus increasing the resistance to crankshaft 52's rotation. In the engine control device 78 of this embodiment, after the fuel injection device 50 stops fuel injection, the ACG starter motor 44 assists the crankshaft 52 in rotating due to inertia. Due to the assistance of the ACG starter motor 44, before engine 42 stops, crankshaft 52 can be rotated to a rotational angle exceeding the rotational angle corresponding to the piston's TDC. As a result, the rotational angle of crankshaft 52 when engine 42 stops is an angle exceeding the rotational angle corresponding to the piston's TDC. Therefore, at the point when engine 42 stops, in the forward rotation direction of crankshaft 52, the rotational angle of crankshaft 52 can be deviated from the rotational angle corresponding to the piston's TDC. When the restart conditions of engine 42 after idling stop are met, it is not necessary to allow crankshaft 52 to return to its original position. Therefore, it is possible to shorten the time from the time the restart conditions of engine 42 are met until engine 42 restarts.

[0063] Furthermore, in the engine control device 78 of this embodiment, the lower the engine speed of the engine 42 at the time when the idle stop condition is met, the higher the torque output of the ACG starter motor 44 is set. The lower the engine speed of the engine 42, the smaller the inertial force that causes the crankshaft 52 to rotate. When the engine speed of the engine 42 is low and the inertial force causing the crankshaft 52 to rotate is small, the torque that the ACG starter motor 44 uses to assist the rotation of the crankshaft 52 is set to be large. As a result, before the engine 42 stops, the crankshaft 52 can be rotated to a rotation angle exceeding the rotation angle corresponding to the top dead center of the piston compression.

[0064] Furthermore, in the engine control device 78 of this embodiment, the starter motor control unit 142 sets the torque output by the ACG starter motor 44 based on the rotation angle of the crankshaft 52 during the period from the start of the idle stop condition until the engine 42 stops. Specifically, the starter motor control unit 142 sets the torque output by the ACG starter motor 44 to be larger as the rotation angle of the crankshaft 52 gets closer to the rotation angle corresponding to the top dead center of the piston of the engine 42. The closer the rotation angle of the crankshaft 52 is to the rotation angle corresponding to the top dead center of the piston of the engine 42, the greater the resistance that hinders the rotation of the crankshaft 52. At the rotation angle of the crankshaft 52 where the resistance is greater, the torque of the ACG starter motor 44 that assists the rotation of the crankshaft 52 is set to be larger. As a result, before the engine 42 stops, the crankshaft 52 can be rotated to a rotation angle exceeding the rotation angle corresponding to the top dead center of the piston.

[0065] Furthermore, the present invention is not limited to the embodiments described above, and various structures can be adopted without departing from the spirit of the present invention.

[0066] [Technical solutions obtained according to the implementation methods] The following describes the technical solutions that can be mastered based on the above embodiments.

[0067] An idle stop control device (78) for a motorcycle (10) includes an engine (42) and a starter motor (44), wherein the starter motor outputs a torque to the crankshaft (52) of the engine (42) to rotate the crankshaft (52). The device includes a condition determination unit (138), an engine control unit (140), and a starter motor control unit (142). The condition determination unit determines that the idle stop condition of the engine (42) is met; the engine control unit stops the engine (42) when the idle stop condition is met; and the starter motor control unit controls the starter motor (44) to output the torque to rotate the crankshaft (52) when the idle stop condition is met. The starter motor control unit (142) sets the torque output by the starter motor (44) based on the engine speed of the engine (42) when the idle stop condition is met. This shortens the time from the start of the engine restart condition until the engine restarts.

[0068] In the aforementioned idle stop control device, the starter motor control unit (142) sets the torque output by the starter motor (44) based on the engine speed (42) when the idle stop condition is met and the rotation angle of the crankshaft (52) after the idle stop condition is met. Thus, before the engine stops, the crankshaft can be rotated to a rotation angle exceeding the rotation angle corresponding to the piston's top dead center during compression.

[0069] In the aforementioned idle stop control device, the starter motor control unit (142) may set the torque output by the starter motor (44) to be larger as the rotation angle of the crankshaft (52) gets closer to the rotation angle corresponding to the top dead center of the piston of the engine (42) during the period from the start of the idle stop condition to the stop of the engine (42). Thus, before the engine stops, the crankshaft can be rotated to a rotation angle exceeding the rotation angle corresponding to the top dead center of the piston.

[0070] In the aforementioned idle stop control device, the starter motor control unit (142) can set the torque output by the starter motor (44) to be greater as the engine speed (42) decreases. This allows the crankshaft to rotate to a rotation angle exceeding the rotation angle corresponding to the piston's top dead center during compression before the engine stops. Explanation of reference numerals in the attached figures

[0071] 42: Engine; 44: ACG starter motor (starter motor); 52: Crankshaft; 78: Engine control unit (idle stop control unit); 138: Condition determination unit; 140: Engine control unit; 142: Starter motor control unit

Claims

1. An idle stop control device (78) for a motorcycle (10), comprising an engine (42) and a starter motor (44), wherein, The starter motor outputs torque to the crankshaft (52) of the engine (42) to rotate the crankshaft (52), characterized in that, It includes a condition determination unit (138), an engine control unit (140), and a starter motor control unit (142), wherein, The condition determination unit determines that the idle stop condition of the engine (42) is met; When the idle stop condition is met, the engine control unit stops the engine (42); When the idle stop condition is met, the starter motor control unit controls the starter motor (44) to output the torque that rotates the crankshaft (52). The starter motor control unit (142) sets the torque output by the starter motor (44) based on the engine speed (42) when the idle stop condition is met. The starter motor control unit (142) sets the torque output by the starter motor (44) based on the engine speed (42) when the idle stop condition is met and the rotation angle of the crankshaft (52) after the idle stop condition is met. During the period from the start of the idle stop condition to the stop of the engine (42), the starter motor control unit (142) sets the torque output by the starter motor (44) to be larger as the rotation angle of the crankshaft (52) gets closer to the rotation angle corresponding to the top dead center of the piston of the engine (42).

2. The idle speed stop control device (78) according to claim 1, characterized in that, The starter motor control unit (142) sets the torque output by the starter motor (44) to be greater as the speed of the engine (42) decreases.

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