Control methods for electric motorcycles

Abstract

The present invention provides a method which is for controlling an electric two-wheel vehicle and which allows a rider to start travelling without any uncomfortable feeling at a travel starting operation by performing a clutch operation.　The control method according to the present disclosure is for controlling an electric two-wheel vehicle that is equipped with a motor (10), a clutch (25), and a stepped transmission (20), said method being characterized by comprising: a disengagement / engagement detection step for detecting a transition from a state where the clutch (25) is disengaged to a state where the clutch (25) has been engaged; an accelerator operation detection step for detecting an amount of accelerator operation performed by the rider after the engagement of the clutch (25); a target motor rotation speed setting step for setting a target motor rotation speed on the basis of the accelerator operation amount; and a motor rotation speed control step for controlling the rotation speed of the motor on the basis of the target motor rotation speed.

Description

Technical Field

[0001] The present invention relates to a control method for an electric two-wheeler.

Background Art

[0002] In saddle-riding type vehicles such as motorcycles, it is possible for the rider to directly convey their intentions to the vehicle, and there is a great charm in the fact that they can ride as if it were a part of their body. For conventional saddle-riding type vehicles driven by an internal combustion engine, the operation targets include throttle opening / closing adjustment by an accelerator grip, braking, and stepped shifting involving clutch operation, which have enabled the rider to drive freely. Due to the increasing concern about environmental problems in recent years, electric two-wheelers driven by an electric motor have been developed for saddle-riding type vehicles as well. Among them, an electric two-wheeler provided with a clutch mechanism that disconnects between the motor and the gear train has also been disclosed (see, for example, International Publication No. 2014-102869).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the case of having a clutch mechanism, when starting by performing a clutch operation, regarding the load change when the clutch changes from the disengaged state to the engaged state, since the inertial weight on the motor shaft is too small, a large decrease in the rotational speed of the motor occurs, and there is a problem that the rider may feel discomfort. Furthermore, there are significant differences between the torque characteristics of electric motors and those of internal combustion engines. For example, when starting off, in a motorcycle driven by an internal combustion engine, even if the rider opens the throttle, there is a time lag before the rotational speed actually increases and the torque rises because of the multiple processes involved, such as intake, fuel injection, and combustion initiation. In other words, torque increases as the rotational speed increases. In contrast, with electric motorcycles, a large torque can be obtained even at low rotational speeds due to the characteristics of the motor, so a large torque can be obtained immediately after starting to ride (see Figure 2). Therefore, in electric motorcycles, it is necessary to control the output of the motor to prevent the rider from experiencing discomfort such as sudden acceleration. This invention provides a control method for an electric motorcycle that allows the rider to start driving without any discomfort when operating the clutch to begin the vehicle. [Means for solving the problem]

[0005] One aspect of the present invention is a control method for an electric motorcycle equipped with a motor, a clutch, and a stepped transmission, comprising: a disengagement detection step for detecting when the clutch has transitioned from a disengaged state to a engaged state; an accelerator operation detection step for detecting the amount of accelerator operation performed by the rider after the clutch has been engaged; a target motor rotation speed setting step for setting a target motor rotation speed based on the amount of accelerator operation; and a motor rotation speed control step for controlling the rotation speed of the motor based on the target motor rotation speed. This specification includes all the contents of Japanese Patent Application No. 2022-054639, filed on March 29, 2022. [Effects of the Invention]

[0006] According to one aspect of the present invention, when the occupant performs a clutch operation to start the vehicle, it is possible to begin driving without any sense of discomfort. [Brief explanation of the drawing]

[0007] [Figure 1]Figure 1 shows the configuration of an electric motorcycle. [Figure 2] Figure 2 compares the torque characteristics of an internal combustion engine with those of an electric motor. [Figure 3] Figure 3 is a block diagram showing the configuration of an ECU that realizes the control method for an electric motorcycle according to the embodiment. [Figure 4] Figure 4 is a flowchart of output control in an electric motorcycle. [Figure 5] Figure 5 is a flowchart of the control method at the start of clutch engagement. [Figure 6] Figure 6 is a flowchart showing the torque map switching control immediately after clutch engagement. [Figure 7] Figure 7 is a flowchart showing the torque map switching control when transitioning to normal driving. [Figure 8] Figure 8 shows the motor torque curve after output control has been applied according to the starting power request map. [Figure 9] Figure 9 shows the motor torque curve after output control has been applied according to the normal driving map. [Figure 10] Figure 10 is a timing chart of the requested output and clutch output rotation speed. [Modes for carrying out the invention]

[0008] [Embodiment] Embodiments of the present invention will be described below with reference to the drawings. Unless otherwise specified, directions such as front, rear, left, and right in the following description are the same as those of the vehicle described below. In the drawings used in the following description, arrows FR indicating the front of the vehicle and UP indicating the top of the vehicle are shown where appropriate. In this specification, an electric motor is referred to as a motor.

[0009] Figure 1 shows the left side view of a saddle-type vehicle (electric motorcycle) 1. In this embodiment, the saddle-type vehicle 1 is an electric motorcycle equipped with a motor instead of an internal combustion engine such as a gasoline engine as its power unit. Similar to motorcycles driven by an internal combustion engine, the saddle-type vehicle 1 is equipped with an accelerator grip, clutch lever, gear shift pedal, etc., as an operating system 2 for the rider to control the saddle-type vehicle 1. The saddle-type vehicle 1 is equipped with a front wheel 3 which is the steering wheel and a rear wheel 4 which is the drive wheel. The rear wheel 4 is supported at the rear of a swing arm (not shown) which is pivotably supported on the vehicle frame (not shown).

[0010] The saddle-type vehicle 1 is equipped with an ECU (Electronic Control Unit) 5, which is a control device for performing various controls, a motor 10 that generates driving force, and a battery 15 that stores electricity. The saddle-type vehicle 1 is equipped with a clutch 25 and a stepped transmission 20 to transmit the driving force P of the motor 10 to the rear wheels 4. The motor 10 and the stepped transmission 20 are controlled by the ECU 5, which performs control according to instructions from the occupant to the control system 2.

[0011] Specifically, the ECU5 is a computer that includes a processor such as a CPU (Central Processing Unit), a ROM (Read Only Memory) on which the program is written, and a RAM (Random Access Memory) for temporary data storage. Various control means are executed when the ECU5, being a computer, executes the program. In place of or in addition to the above-mentioned ECU5, all or part of the ECU5 may also be configured with hardware that includes one or more electronic circuit components.

[0012] The motor 10 is a three-phase electric motor or the like. The battery 15 may be a lithium-ion battery or the like. The motor 10 and the battery 15 are fixed to the vehicle body frame. The stepped transmission 20 is a power transmission mechanism that changes the rotational speed by combining a plurality of gears. The clutch 25 is a device that is attached between the motor 10 and the stepped transmission 20 and transmits or blocks the driving force P to the stepped transmission 20. The clutch 25 operates when the occupant operates a clutch lever (not shown).

[0013] Figure 3 is a block diagram showing the configuration of the ECU 5 that realizes the control method of the electric two-wheeler according to the present embodiment. The ECU 5 is connected to a disconnection detection means 40 that detects the engagement state of the clutch and an accelerator operation amount detection means 50 that detects the accelerator operation amount. The ECU 5 is connected to a motor rotation speed detection means 60 that detects the motor rotation speed of the motor 10 and a vehicle speed measurement means 70 that measures the vehicle speed of the saddle-riding type vehicle 1.

[0014] The ECU 5 includes a detection information acquisition means 24 that acquires information detected by various detection means. The ECU 5 also includes an arithmetic means 26 that performs an arithmetic operation for output control based on the acquired information. The ECU 5 performs output control according to the running state and the like, and includes a determination means 27 that makes a determination for that purpose. The operation of the determination means 27 will be described later. The ECU 5 includes a motor rotation speed setting means 29 that sets the motor rotation speed based on a torque map, a motor rotation speed control means 31 that controls the motor 10 to rotate at the set motor rotation speed, and an output control means 33 that controls the entire output. Each operation will be described later. The ECU 5 also includes a storage means 35 that stores programs, data for realizing various means, and information on the torque map described later. The storage means 35 is realized by a storage device such as an SSD (Solid State Drive). The detection information acquisition means 24 is realized by an interface circuit or the like. The arithmetic means 26, the determination means 27, the motor rotation speed setting means 29, the motor rotation speed control means 31, and the output control means 33 are realized by executing programs stored in the storage means 35.

[0015] Figure 4 is a flowchart of output control in an electric motorcycle. First, the accelerator operation amount detection means 50 detects the amount of accelerator operation by the rider (step TA1). Specifically, it detects the throttle opening, equivalent to that in an internal combustion engine, from the rotation angle of the accelerator grip, etc. Next, the ECU 5's detection information acquisition means 24 acquires the accelerator operation amount from the accelerator operation amount detection means 50. The calculation means 26 converts the accelerator operation amount into a requested output (step TA2). Next, the calculation means 26 converts the requested output into a corresponding predetermined current value (step TA3). Then, the output control means 33 controls the battery 15 so that it outputs a predetermined current value to the motor 10 (step TA4). As a result, the motor 10 outputs torque corresponding to the requested output (step TA5).

[0016] Figure 5 is a flowchart of the control method for the electric motorcycle at the start of clutch engagement. The engagement state of the clutch 25 detected by the disengagement detection means 40 is acquired by the detection information acquisition means 24 (Step SA1: Disengagement detection step). The ECU 5 determines whether the clutch 25 is in the engagement start state using the determination means 27 (Step SA2: Engagement start detection step). If it is determined that the clutch 25 is in the engagement start state (Step SA2: YES), the ECU 5 acquires the accelerator operation amount detected by the accelerator operation amount detection means 50 using the detection information acquisition means 24 (Step SA3: Accelerator operation detection step). The ECU 5 determines whether the accelerator operation amount is zero using the determination means 27 (Step SA4). If it is determined that the accelerator operation amount is not zero (Step SA4: NO), the output control means 33 of the ECU 5 performs output control on the battery 15 and motor 10 based on the start preparation request output (Step SA5: Output control step). Specifically, output control includes a target motor speed setting step, which sets a target motor speed in order to output a request output for launch preparation, and a motor speed control step, which controls the motor speed based on the target motor speed. When it is determined that the clutch 25 is not in the starting engagement state (step SA2: NO), the process returns to step SA1. When it is determined that the accelerator operation amount is zero (step SA4: YES), the process returns to step SA1.

[0017] Here, the starting preparation required output is an output value for preventing the vehicle speed from exceeding a preset running resistance vehicle speed regardless of the clutch operation state. For example, on a flat road, the starting preparation required output is calculated from the magnitude of the running resistance mainly composed of rolling resistance.

[0018] FIG. 6 is a flowchart showing the torque map switching control immediately after the clutch 25 is engaged. Information about the torque map may be stored by the storage means 35. The ECU 5 stores a plurality of torque maps by the storage means 35, and the ECU 5 switches the torque map according to the running state. Among the plurality of torque maps, for example, there may be a torque map with gentle and reassuring characteristics from starting to low-speed running, and a torque map with full torque characteristics in the medium and low speed ranges. When following different torque maps, the straddle-type vehicle 1 can realize different driving flavors. In other words, the output control includes a torque map switching step of switching the torque map that the motor 10 follows based on the motor rotation speed and / or the vehicle speed.

[0019] First, let's explain the torque map switching control immediately after clutch 25 engagement. The ECU 5 acquires motor speed information detected by the motor speed detection means 60 using the detection information acquisition means 24 (Step SB1: Motor speed detection step). The ECU 5 determines whether the motor speed has decreased or not using the determination means 27 (Step SB2). If the determination means 27 determines that the motor speed has not decreased (Step SB2: NO), the ECU 5 acquires vehicle speed information measured by the vehicle speed measurement means 70 using the detection information acquisition means 24 (Step SB3: Vehicle speed measurement step). The ECU 5 determines whether the vehicle speed has exceeded a predetermined threshold using the determination means 27 (Step SB4). If the vehicle speed has exceeded a predetermined threshold (Step SB4: YES), the output control means 33 switches the torque map to the starting request output map (Step SB5). If the determination means 27 determines that the motor rotation speed is decreasing (step SB2: YES), the output control means 33 switches the torque map to the starting request output map (step SB5: first switching step). If the determination means 27 determines that the vehicle speed is below a predetermined threshold (step SB4: NO), the process returns to step SB1.

[0020] Figure 7 is a flowchart showing the torque map switching control when transitioning to normal driving. The ECU 5 acquires the clutch engagement state of the clutch 25 detected by the disengagement detection means 40 using the detection information acquisition means 24 (step SC1). The ECU 5 determines whether the clutch 25 is in a fully engaged state using the determination means 27 (step SC2). In this case, the fully engaged state of the clutch may be either the state in which the clutch 25 is fully engaged or the state in which the difference in clutch rotation has disappeared. If it is determined that the clutch 25 is in a fully engaged state (step SC2: YES), the output control means 33 switches the torque map to the normal driving map (step SC3: second switching step). If it is determined that the clutch 25 is not in a fully engaged state (step SC2: NO), the process returns to step SC1.

[0021] Figure 8 shows the motor torque curve after output control has been applied. Specifically, the output control follows a starting request output map. The horizontal axis represents motor rotation speed, and the vertical axis represents torque. A torque curve corresponding to the accelerator operation is set. At very low rotation speeds (around 0 rpm), the output control means 33 controls the motor 10 so that the starting preparation request output is output. In the low rotation range up to 2000 rpm, the output control means 33 controls the motor 10 so that an output equivalent to the stall rotation speed is output. If the normal motor torque were transmitted, a large load change would occur when the clutch is engaged, causing a large drop in rotation speed. Torque control is performed to prevent the occupant from feeling as if the engine is stalling at this time.

[0022] Figure 9 shows the output control according to the normal driving map. The horizontal axis represents motor speed, and the vertical axis represents torque. A torque curve is set according to the accelerator input. Here, the normal driving map outputs a larger torque than the starting-requested output map when the accelerator input is large, for example, in the rotational speed range of 4000 rpm to 6000 rpm (region X). This tuning enables powerful driving in the mid-speed range. Furthermore, in region Z of Figure 9, the map is designed so that torque decreases as rotational speed increases. This has the effect of encouraging the system to shift up and return to an efficient driving region once it has moved outside of that region.

[0023] Figure 10 is a timing chart of requested output and clutch output rotational speed. Line 101 schematically represents the timing chart of clutch operation by the occupant. In region A, the clutch is disengaged, and in region B, the clutch is fully engaged. Line 103 schematically represents the amount of accelerator operation performed by the occupant at the same time. Line 105 shows the motor rotational speed (dashed line) and clutch output rotational speed (solid line) with output control according to the amount of accelerator operation. Line 107 simply represents the control timing of the motor 10 by the output control means 33. In region C, the motor 10 is controlled to output zero. In region D, the motor 10 is controlled to increase its rotational speed in accordance with the increase in accelerator operation. In region E, the clutch is in a half-clutch state, and the clutch 25 is transitioning to the engaged state, so output control is performed according to the engaged state. In region F, the clutch 25 is fully engaged, so the torque map is switched to the normal driving map, and output control is performed accordingly. Line 109 indicates the control of the requested output. In region G, the clutch 25 is not engaged, so the requested output is zero. In region H, the clutch has started to engage, so an output equivalent to the driving resistance (requested output for starting preparation) is requested. In region I, acceleration has started, so the torque map is switched to the requested output map for starting. Then, in region J, the clutch 25 is fully engaged, so the torque map is switched to the normal driving map.

[0024] [Configurations supported by the above embodiment] The above embodiment supports the following configuration:

[0025] (Configuration 1) A control method for an electric motorcycle equipped with a motor, a clutch, and a stepped transmission, comprising: a disengagement detection step for detecting when the clutch has transitioned from a disengaged state to a engaged state; an accelerator operation detection step for detecting the amount of accelerator operation performed by the rider after the clutch has been engaged; a target motor rotation speed setting step for setting a target motor rotation speed based on the amount of accelerator operation; and a motor rotation speed control step for controlling the rotation speed of the motor based on the target motor rotation speed. This configuration makes it possible to suppress the decrease in motor speed caused by load fluctuations when the clutch is engaged. As a result, it eliminates any discomfort during driving after clutch operation.

[0026] (Configuration 2) A control method for an electric motorcycle according to Configuration 1, comprising a clutch engagement start detection step for detecting the start of clutch engagement, and an output control step in which, when the clutch engagement start is detected in the clutch engagement start detection step, output control is initiated based on a predetermined starting preparation request output. With this configuration, the load increases as the clutch engages, so adding the necessary output control can prevent insufficient power output. Furthermore, by controlling the output to only the predetermined required power, sudden acceleration can be suppressed. This results in the excellent effect of enabling safe driving without any discomfort for the occupant.

[0027] (Configuration 3) A control method for an electric motorcycle according to Configuration 2, comprising: a motor rotation speed detection step for detecting the motor rotation speed; a vehicle speed measurement step for measuring the vehicle speed; and a torque map switching step for switching the torque map to which the motor follows based on at least one of the motor rotation speed, the vehicle speed, and the clutch engagement state. This configuration allows the motor characteristics to be switched to an appropriate torque curve according to the driving conditions. This has the excellent effect of providing an electric motorcycle that can give the rider the joy of freely controlling a vehicle similar to that of a motorcycle equipped with an internal combustion engine.

[0028] (Configuration 4) A control method for an electric motorcycle according to Configuration 3, characterized in that, after the start of output control based on the start preparation request output, a first switching step is detected in which the motor rotation speed decreases or the vehicle speed exceeds a predetermined threshold, and the torque map followed by the motor is switched to a start request output map set based on the stall rotation speed of the motor. This configuration allows the power characteristics at startup to be similar to those of an internal combustion engine. Therefore, it has the effect of reducing the discomfort felt by the rider when starting an electric motorcycle.

[0029] (Configuration 5) A control method for an electric motorcycle according to Configuration 3 or Configuration 4, characterized in that it has a clutch engagement completion detection step for detecting the completion of clutch engagement, and a second switching step for switching the torque map followed by the motor to a normal driving map when the clutch engagement completion is detected in the clutch engagement completion detection step. This configuration allows for driving that follows a torque curve optimized for motor efficiency during normal operation.

[0030] The above embodiments represent one way in which the present invention is applied, and the present invention is not limited to the above embodiments.

[0031] For example, the operation step units shown in Figures 3, 5, 6, and 7 are divided according to the main processing content in order to facilitate understanding of the control method of the electric motorcycle, and the present invention is not limited by the way the processing units are divided or the names of the units. Depending on the processing content, it may be further divided into more step units. Alternatively, it may be divided so that one step unit includes even more processing. Furthermore, the order of the steps may be changed as appropriate, as long as it does not impede the spirit of the present invention. [Explanation of Symbols]

[0032] 1. Saddle-type vehicle (electric two-wheeled vehicle) 10 motors 20-speed transmission 25 Clutch

Claims

1. A control method for an electric motorcycle comprising a motor (10), a clutch (25), and a stepped transmission (20), A disengagement detection step that detects when the clutch (25) has transitioned from a disengaged state to a engaged state, After the clutch (25) is engaged, an accelerator operation detection step is performed to detect the amount of accelerator operation performed by the occupant, A target motor rotation speed setting step, which sets a target motor rotation speed based on the accelerator operation amount, A motor rotation speed control step in which the rotation speed of the motor is controlled based on the target motor rotation speed, A clutch engagement start detection step for detecting the start of engagement of the clutch (25), If the clutch engagement start is detected in the engagement start detection step, an output control step is performed to start output control based on a starting preparation request output that is set so that the vehicle speed of the electric motorcycle does not increase beyond a vehicle speed that generates a set driving resistance, A control method for an electric motorcycle, characterized by having the following features.

2. The control method for an electric motorcycle according to claim 1, characterized in that, after the clutch engagement start detection step detects the start of engagement, if it is detected that the amount of accelerator operation is not zero, the output control step is executed.

3. A motor rotation speed detection step that detects the motor rotation speed, A vehicle speed measurement step that measures vehicle speed, A torque map switching step that switches the torque map to which the motor (10) follows, based on at least one of the motor rotation speed, the vehicle speed, and the engagement state of the clutch (25); A control method for an electric motorcycle according to claim 1 or 2, characterized by having the following features.

4. The control method for an electric motorcycle according to claim 3, further comprising a first switching step in which, after the start of output control based on the start preparation request output, the motor rotation speed decreases or the vehicle speed exceeds a predetermined threshold, the torque map followed by the motor (10) is switched to a start request output map set based on the stall rotation speed of the motor (10).

5. The clutch has a clutch engagement completion detection step for detecting the completion of clutch engagement, The control method for an electric motorcycle according to claim 3, further comprising a second switching step in which, when the completion of engagement of the clutch (25) is detected in the engagement completion detection step, the torque map followed by the motor (10) is switched to a normal driving map.

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