Regeneration control method and straddle type vehicle

Abstract

The invention discloses a regeneration control method and a straddle type vehicle. A regeneration control method for a vehicle and a straddle-type vehicle as an example of the vehicle are provided. The regeneration control method is executed in a processing circuit of a vehicle including an electric motor as a driving source, and includes: determining whether a start condition of regeneration control for requesting the electric motor to generate regeneration torque is satisfied; acquiring a degree to which the accelerator operation amount decreases over time prior to the start of regeneration control; and determining a required regenerative torque, which is a regenerative torque required for the electric motor, on the basis of the degree of reduction in the accelerator operation amount.

Description

Technical Field

[0001] The present disclosure relates to a regeneration control method and a straddle-type vehicle. Background Art

[0002] JPH05-64304A describes a regenerative braking device for an electric vehicle.

[0003] A regenerative braking apparatus for an electric vehicle determines a deceleration state from a motor rotation speed and an accelerator signal and performs regenerative braking according to the deceleration state. Summary of the invention

[0004] When regeneration control is performed in an electric vehicle, there is a demand to make the braking feeling felt by the user close to the feeling expected by the user.

[0005] Aspects of the present disclosure provide a regeneration control method and a straddle-type vehicle capable of making a braking feeling felt by a user close to a feeling expected by the user when performing regeneration control.

[0006] According to an illustrative aspect of the present disclosure, a regeneration control method for a vehicle, which is executed in a processing circuit of a vehicle including an electric motor as a drive source, includes: determining whether a start condition for regeneration control for requesting the electric motor to generate a regeneration torque is satisfied; before the regeneration control starts, obtaining a degree of decrease in an accelerator operation amount over time; and determining a required regeneration torque based on the degree of decrease in the accelerator operation amount, the required regeneration torque being a regeneration torque required by the electric motor.

[0007] According to another illustrative aspect of the present disclosure, a regeneration control method for a vehicle, which is executed in a processing circuit of a vehicle including an electric motor as a drive source, includes: determining whether a start condition of regeneration control for requesting the electric motor to generate a regeneration torque is satisfied; after determining that the start condition is satisfied, determining a required regeneration torque, the required regeneration torque being a regeneration torque required by the electric motor. An absolute value of the required regeneration torque determined in a predetermined period from the start of the regeneration control is greater than an absolute value of the required regeneration torque determined after the predetermined period has elapsed.

[0008] According to another illustrative aspect of the present disclosure, a straddle-type vehicle includes: an accelerator operator operated by a user; a drive wheel; an electric motor as a drive source for driving the drive wheel; and a processing circuit configured to control a regenerative torque of the electric motor for braking the drive wheel. The processing circuit is configured to: determine whether a start condition for regenerative control for requesting the electric motor to generate a regenerative torque is satisfied; before the regenerative control is started, obtain a degree of decrease in an accelerator operation amount over time; and determine a required regenerative torque based on the degree of decrease in the accelerator operation amount, the required regenerative torque being a regenerative torque required by the electric motor.

[0009] According to the present disclosure, it is possible to make the braking feeling felt by the user close to the feeling expected by the user when the regeneration control is performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic diagram of a vehicle according to an embodiment.

[0011] Figure 2 It is shown Figure 1 A block diagram of the electrical configuration of a vehicle.

[0012] Figure 3 is a graph showing an example of a normal torque map and a strong regeneration torque map.

[0013] Figure 4 1 is a flowchart showing the flow of vehicle travel control performed by the controller.

[0014] Figure 5 : is a flowchart showing the regeneration control flow.

[0015] Figure 6 is a graph showing an example of a method of calculating a reduction degree.

[0016] Figure 7 is a graph showing the temporal variation of the coefficient. DETAILED DESCRIPTION

[0017] Hereinafter, embodiments will be described with reference to the accompanying drawings.

[0018] Vehicle Configuration

[0019] Figure 1 is a schematic diagram of a vehicle 1 according to an embodiment. In the present preferred embodiment, the vehicle 1 is a straddle-type electric motorcycle. The vehicle 1 includes a vehicle body 2 and a battery pack 3. The battery pack 3 can be attached to and detached from the vehicle body 2. The vehicle body 2 is supported by a front wheel 4 as a driven wheel and a rear wheel 5 as a driving wheel. An electric motor 6 as a driving source for travel is supported by the vehicle body 2. The electric motor 6 generates a driving force for travel to be transmitted to the rear wheel 5 as a driving wheel. The driving torque generated by the electric motor 6 is transmitted to the rear wheel 5 via a power transmission mechanism 7. The electric motor 6 is rotatable forward and backward. The electric motor 6 functions as a driving source for travel. A rotation speed sensor 22 (see FIG. 2 ) that detects the rotation speed of the output shaft of the electric motor 6 Figure 2) is provided in the electric motor 6. The electric motor 6 also functions as a generator that generates electricity using power transmitted from the drive wheel during deceleration of the vehicle 1, etc. The power transmission mechanism 7 includes a speed reducer 7a that decelerates the rotation of the electric motor 6, and a mechanism 7b (for example, a chain transmission mechanism, a belt transmission mechanism, etc.) that transmits the rotational power output from the speed reducer 7a to the wheel axle of the rear wheel 5.

[0020] The vehicle body 2 includes a vehicle body frame, and the vehicle body frame includes a head pipe 11 and a pair of left and right main frames 12 extending rearward from the head pipe 11. The head pipe 11 rotatably supports a steering shaft 13. A front fork 14 extending substantially vertically is connected to the steering shaft 13, and the front wheel 4 is rotatably supported at the lower end portion of the front fork 14. A bar-type handlebar 15 extending in the left-right direction is connected to the upper end portion of the steering shaft 13. An accelerator operator 15a for adjusting the drive torque generated by the electric motor 6 is provided on the handlebar 15. In the present embodiment, the accelerator operator 15a is an accelerator grip, i.e., the right grip of the handlebar 15.

[0021] When the accelerator operator 15a rotates from the reference position in a predetermined first moving direction, the accelerator sensor 21 (see Figure 2 ) detects the operation amount (hereinafter referred to as the accelerator operation amount). The accelerator sensor 21 is implemented by, for example, a position sensor that detects the rotation amount of the grip. For example, the accelerator sensor 21 can be implemented by a magnetic field detection sensor using a Hall IC. An urging force is applied to the accelerator operator 15a so that the accelerator operator 15a returns to the reference position in a state where no operation by the user as the driver is applied. In the present embodiment, the predetermined first moving direction is set to a direction opposite to the clockwise direction when viewed from the right side of the vehicle body. Relative to the reference position, the output of the electric motor 6 increases with the increase of the movement amount in the first moving direction, in other words, with the increase of the acceleration operation amount.

[0022] The meter device 8 is provided on the front side of the handlebar 15 . The meter device 8 displays the running speed, the motor rotation speed, the battery remaining amount, etc. The meter device 8 is supported by the head pipe 11 via a bracket 16 .

[0023] The battery pack 3 is accommodated in a battery box 17. The battery box 17 is disposed between a pair of main frames 12 in the left-right direction and is fixed to the pair of main frames 12. The battery pack 3 includes a chargeable and dischargeable battery 3a and a battery management unit. The battery 3a, the battery management unit, etc. of the battery pack 3 accommodated in the battery box 17 are electrically connected to the electronic equipment on the vehicle body 2 side.

[0024] Electrical configuration

[0025] Figure 2 It is shown Figure 1 1 is a block diagram of an electrical configuration of a vehicle 1. A controller 31 and an inverter 32 are fixed to the vehicle body 2 of the vehicle 1. The controller 31 includes a processor, a memory, an I / O interface, etc. in terms of hardware. The memory includes, for example, a storage device such as a hard disk or a flash memory, and a main memory, which is a RAM. The storage device stores a program for issuing a control command to the electric motor 6. The processor, memory, etc. included in the controller 31 are examples of a processing circuit.

[0026] The controller 31 receives the accelerator operation amount detected by the accelerator sensor 21. In this specification, the accelerator operation amount may also be referred to as the accelerator opening. The controller 31 receives the motor rotation speed detected by the rotation speed sensor 22. The controller 31 and the inverter 32 are communicatively connected to a controller area network (CAN) 30. The battery 3a is connected to the electric motor 6 via the inverter 32.

[0027] When the vehicle 1 is running, the controller 31 performs power running control or regeneration control based on the received accelerator operation amount and the motor rotation speed. In the power running control, the electric motor 6 is required to generate a driving torque for causing the vehicle 1 to run. More specifically, in the power running control, the controller 31 generates a control command for causing the electric motor 6 to generate a driving torque (i.e., a torque in a predetermined positive direction), and outputs the control command to the inverter 32. The positive direction of the electric motor 6 is the rotation direction of the electric motor 6 that generates a driving torque for accelerating the vehicle 1 forward. The inverter 32 is controlled by the controller 31 to convert the DC power discharged from the battery 3a into AC power and supply the AC power to the electric motor 6.

[0028] In the regenerative control, the controller 31 requests the electric motor 6 to generate a regenerative torque. More specifically, in the regenerative control, the controller 31 generates a regenerative control command and outputs the regenerative control command to the inverter 32. Upon receiving the regenerative control command, the inverter causes the electric motor 6 to generate a regenerative torque (i.e., a torque in a negative direction opposite to a positive direction) so as to brake the vehicle 1. The inverter 32 converts the AC power generated by the electric motor 6 as a generator into DC power and supplies the DC power to the battery 3a to charge the battery 3a.

[0029] The controller 31 includes a normal torque acquisition unit 41, a strong regeneration torque acquisition unit 42, a strong regeneration selection unit 43, and a torque determination unit 44 in terms of functions. The normal torque acquisition unit 41, the strong regeneration torque acquisition unit 42, the strong regeneration selection unit 43, and the torque determination unit 44 are implemented by a processor that performs arithmetic processing on a program read from a storage device to a main memory. The normal torque acquisition unit 41, the strong regeneration torque acquisition unit 42, the strong regeneration selection unit 43, and the torque determination unit 44 perform driving control of the vehicle 1 for switching between power running control and regeneration control.

[0030] The normal torque acquisition unit 41 uses a normal torque map to acquire a torque corresponding to the accelerator operation amount and the motor rotation speed. The strong regenerative torque acquisition unit 42 uses a strong regenerative torque map to acquire a torque corresponding to the accelerator operation amount and the motor rotation speed. The torque acquired by the normal torque acquisition unit 41 using the normal torque map is called a normal torque T1. In addition, the torque acquired by the strong regenerative torque acquisition unit 42 using the strong regenerative torque map 12 is called a strong regenerative torque T2. The memory of the controller 31 stores the normal torque map and the strong regenerative torque map. Both the normal torque map and the strong regenerative torque map show the correspondence between the accelerator operation amount and the electric motor rotation speed, and the torque.

[0031] The normal torque map may be referred to as a first torque map. The strong regeneration torque map may be referred to as a second torque map. The strong regeneration torque map is set so that the regeneration torque becomes larger than the regeneration torque obtained by the normal torque map even under the same conditions of the motor rotation speed and the accelerator operation amount. The details of the map will be described later. The normal torque acquisition unit 41 and the strong regeneration torque acquisition unit 42 output the torque information acquired from the corresponding maps to the torque determination unit 44.

[0032] The normal torque acquisition unit 41 outputs the acquired torque information to the strong regeneration selection unit 43. The strong regeneration selection unit 43 outputs a selection instruction on whether to select the strong regeneration torque based on the torque information provided from the normal torque acquisition unit 41. In the present embodiment, the strong regeneration selection unit 43 issues a selection command to the torque determination unit 44 to select the required torque based on the regeneration torque information from the strong regeneration torque acquisition unit 43 within a predetermined period after the torque information given from the normal torque acquisition unit 41 is switched to the strong regeneration torque. In other words, the strong regeneration selection unit 43 outputs a selection command indicating whether to use the strong regeneration torque information output from the strong regeneration torque acquisition unit 43 based on a predetermined selection condition.

[0033] The torque determination unit 44 determines the required torque Tr required by the electric motor 6. During power operation control, the required torque Tr is a positive value, and during regeneration control, the required torque Tr is a negative value. In the following description, the required torque Tr during power operation control is also referred to as the required drive torque Tr, and the required torque Tr during regeneration control is also referred to as the required regeneration torque Tr. Specifically, the torque determination unit 44 outputs the required torque Tr to the inverter 30 based on the torque information supplied from the normal torque acquisition unit 41 and the strong regeneration torque acquisition unit 42 and the selection instruction supplied from the strong regeneration selection unit 43. More specifically, the torque determination unit 44 determines that the regeneration torque is different based on the time change of the accelerator operation amount before the start of regeneration (the degree of reduction described later).

[0034] The torque determination unit 44 determines the required drive torque Tr using the normal torque T1 acquired by the normal torque acquisition unit 41. The torque determination unit 44 determines the required regenerative torque Tr using both the normal torque T1 acquired by the normal torque acquisition unit 41 and the strong regenerative torque T2 acquired by the strong regenerative torque acquisition unit 42. A method of determining the required torque Tr will be described in detail later. The torque determination unit 44 outputs a control command to the inverter 32 for causing the electric motor 6 to generate the determined required torque Tr.

[0035] Will refer to Figure 3 Describe the normal torque diagram and the strong regeneration torque diagram. Figure 3 Two normal torque maps M1a and M1b and one strong regenerative torque map M2 are shown. Figure 3 Each torque graph shown in is a graph showing the correspondence relationship between the motor rotation speed and the torque for each accelerator operation amount, and the horizontal axis indicates the motor rotation speed and the vertical axis indicates the torque.

[0036] Depend on Figure 3 The normal torque diagram M1a indicated by the solid line in FIG. 1 shows the corresponding relationship between the motor rotation speed and the normal torque T1 when the accelerator operation amount is 50%. Figure 3 The normal torque diagram M1b indicated by the single-point chain line in FIG. 1 shows the corresponding relationship between the electric motor rotation speed and the normal torque T1 when the accelerator operation amount is 0%. Figure 3 The strong regenerative torque diagram M2 indicated by the dotted line in FIG shows the corresponding relationship between the electric motor rotation speed and the strong regenerative torque T2 when the accelerator operation amount is 0%. In each torque diagram, the positive torque indicates the driving torque for driving the driving wheel, and the negative torque indicates the regenerative torque for braking the driving wheel. The normal torque T1 with a negative value can also be referred to as the normal regenerative torque T1.

[0037] The normal torque map is set so that the torque in the positive direction increases as the accelerator operation amount increases. For example, Figure 3 A normal torque map M1a in which the accelerator operation amount is 50% is shown, but a normal torque map in which the accelerator operation amount is greater than 50% is positioned at Figure 3 The normal torque diagram in which the accelerator operation amount is less than 50% is located in the area above the curve M1a in Figure 3 In the area below the curve M1a in .

[0038] In the normal torque map, the positive torque (driving torque) is set to become smaller as the motor rotation speed increases even with the same accelerator operation amount (see Figure 3 The normal torque map M1a in FIG. 1 is set so that the regeneration torque is generated when the motor rotation speed is equal to or higher than the predetermined slow speed A when the accelerator operation amount is zero. In the normal torque map, when the accelerator operation amount is zero, the regeneration amount is set to be different according to the motor rotation speed. For example, the motor rotation speed is set so that the regeneration amount becomes the maximum at a predetermined regeneration amount maximum speed B, and the regeneration amount becomes smaller as the motor rotation speed deviates from the maximum speed B (see FIG. 1 ). Figure 3 Normal torque diagram M1b).

[0039] In the normal torque map, the torque is interpolated based on the data of each adjacent torque rotation speed. Although the two normal torque maps M1a and M1b are Figure 3 , but in practice, a plurality of normal torque maps corresponding to the values ​​of a plurality of accelerator operation amounts (for example, a plurality of accelerator operation amounts are 0%, 10%, 20%, ..., 100%) are pre-stored in the memory. For example, when the accelerator operation amount is 2%, linear interpolation is performed on the torque obtained from the normal torque map in which the accelerator operation amount is 0% and the torque obtained from the normal torque map in which the accelerator operation amount is 10% so as to obtain the torque in which the accelerator operation amount is 2%. According to the normal torque map based on the present embodiment, even when the accelerator operation amount is a value exceeding zero, if the accelerator operation amount is a very small value (such as 5% or less), for example, the torque corresponding to the motor rotation speed near the maximum speed of the regeneration amount is set to a negative value, that is, the regeneration torque. In this way, even in the normal torque map other than when the accelerator operation amount is 0%, the normal torque T1 can take a negative value in the entire area or a partial area of ​​the motor rotation speed.

[0040] In the strong regenerative torque map, when the accelerator operation amount is zero, the regenerative torque is set to be larger than the regenerative torque in the normal torque map if the conditions of the motor rotation speed are the same. For example, from the comparison between the normal torque map M1b with the accelerator operation amount of 0% and the strong regenerative torque map M2, it can be seen that when comparing the normal regenerative torque T1 and the strong regenerative torque T2 corresponding to the same accelerator operation amount and the same motor rotation speed, the absolute value of the strong regenerative torque T2 is smaller than the absolute value of the normal regenerative torque T1. That is, the strong regenerative torque map is a torque map for obtaining a stronger regenerative braking force than the normal torque map. For example, in the strong regenerative torque map, the regenerative torque can be set to be generated when the motor rotation speed exceeds zero. In addition, in the strong regenerative torque map, the rotation speed is set so that the regeneration amount becomes maximum at a speed C that is higher than the maximum speed B of the regeneration amount set in the normal torque map, and the regeneration amount becomes smaller as the motor rotation speed deviates from the maximum speed C (see Figure 3 Therefore, the strong regenerative torque map is set to generate a regenerative torque greater than the regenerative torque of the normal torque map.

[0041] Figure 3 A strong regenerative torque map M2 showing the correspondence between the motor rotation speed and the strong regenerative torque T2 when the accelerator operation amount is 0% is shown, but a plurality of strong regenerative torque maps corresponding to the values ​​of a plurality of accelerator operation amounts, respectively, may be pre-stored in the memory. However, since the strong regenerative torque map is a map used when performing regenerative control, only maps corresponding to the accelerator operation amount for which regenerative control can be performed are prepared. For example, when a normal torque map in which the accelerator operation amount is 5% or less includes a torque of a negative value, a plurality of strong regenerative torque maps in which the accelerator operation amount is 5% or less may be prepared. For example, a torque map in which the torque is zero at any motor rotation speed may be prepared as a strong regenerative torque map in which the accelerator operation amount is a predetermined small positive value. In this case, the torque corresponding to the accelerator operation amount between 0% and a small value may be obtained by linearly interpolating the torque obtained from the strong regenerative torque map in which the accelerator operation amount is 0% and the torque obtained from the normal torque map in which the accelerator operation amount is a small value.

[0042] Ride Control

[0043] Next, we will refer to Figure 4 and Figure 5 The driving control of the vehicle 1 by the controller 31 is described. The driving control of the vehicle 1 by the controller 31 is performed by the controller 31 reading and executing a program stored in the memory of the controller 31. The controller 31 switches between the power running control and the regeneration control of the electric motor 6 according to the acquired accelerator operation amount and the electric motor rotation speed.

[0044] Specifically, in the travel control, the controller 31 receives the accelerator operation amount from the accelerator sensor 21 and receives the electric motor rotation speed from the rotation speed sensor 22 (step S1 ).

[0045] The controller 31 , more specifically, the normal torque acquisition unit 41 acquires the normal torque T1 corresponding to the accelerator operation amount and the electric motor rotation speed using the normal torque map (step S2 ).

[0046] The controller 31, more specifically, the strong regeneration selection unit 43 determines whether a predetermined regeneration start condition is satisfied (step S3). In the present embodiment, the regeneration start condition is set to the condition that the normal torque T1 acquired in step S2 has changed from a positive value to a negative value.

[0047] When it is determined that the regeneration start condition is not satisfied (step S3: "NO"), the controller 31, more specifically, the torque determination unit 44 determines the required torque Tr (i.e., the required drive torque Tr) to be the normal torque T1 acquired in step S2, and outputs a control command to the inverter 32 (step S4). After step S4, the process returns to step S1. In this way, when it is determined in step S3 that the regeneration start condition is not satisfied, steps S1, S2, and S4 are repeated, and a power running control for generating a travel drive force by the electric motor 6 using the electric power from the battery 3a is performed.

[0048] When it is determined that the regeneration start condition is satisfied (step S3: YES), the controller 31 switches the travel control from the power running control to the Figure 5 Regeneration control shown.

[0049] Regeneration Control Overview

[0050] The details of the regeneration control method according to the present embodiment and an outline of the regeneration control method will be described. First, a comparison with the regeneration control of an engine vehicle using an internal combustion engine as a driving source for travel will be described. For example, when a user driving an engine vehicle performs a sudden shutdown operation in which the accelerator operation amount is suddenly reduced from a relatively large value to 0%, a strong engine brake is applied, and the user obtains a strong sense of deceleration or impact immediately after performing the sudden shutdown operation. When the user performs an operation in which the accelerator operation amount is changed from a relatively small value to 0% or an operation in which the accelerator operation amount is slowly reduced from a relatively large value, a strong sense of deceleration or impact is not obtained. When a user who is familiar with the driving of an engine vehicle drives an electric vehicle, the user may feel uncomfortable if the braking feeling during deceleration is far different from the braking feeling during deceleration of the engine vehicle as described above.

[0051] When the user is performing a sudden closing operation of suddenly reducing the accelerator operation amount from a relatively large value to 0%, there is a high possibility that the user desires to decelerate the vehicle relatively suddenly. In addition, when the user performs an operation of slowly reducing the accelerator operation amount from a relatively large value, there is a high possibility that the user does not desire the vehicle to decelerate suddenly. In an electric vehicle, it is expected that a braking force will be generated according to the user's intention.

[0052] For example, when a straddle-type vehicle approaches a curve in a road during travel, the user decelerates the straddle-type vehicle and turns the straddle-type vehicle before approaching the curve. When a large braking force is applied during deceleration, the load applied to the front wheel is larger than the load applied to the rear wheel. This can lead to an improvement in the steering ease of the straddle-type vehicle. Also from the viewpoint of improving the steering ease of the straddle-type electric vehicle, it is desirable to generate a strong braking force when the user performs a sudden closing operation.

[0053] To achieve at least one desired feeling, in the electric vehicle 1 according to the present embodiment, the absolute value of the required regeneration torque Tr determined during a predetermined period from the start of regeneration control is set larger than the absolute value of the required regeneration torque Tr determined after the predetermined period has elapsed.

[0054] More specifically, the controller 31 acquires the degree d of reduction of the accelerator operation amount over time before the regeneration control starts. The reduction degree d is an index for determining the speed of the operation performed by the user on the accelerator operator 15a when the vehicle 1 is decelerated and the change value of the operation amount. In other words, the reduction degree d indicates how the accelerator operation amount is reduced in the period until the regeneration control starts. In other words, the reduction degree d is an index for determining the degree of deceleration expected by the user. In other words, the reduction degree d can be a temporary change per unit time of the accelerator operation for returning the accelerator operator 15a to the reference position, or a temporary change per unit time of the deceleration operation.

[0055] The controller 31 determines the required regenerative torque Tr based on the degree of reduction d of the accelerator operation amount. Specifically, when the degree of reduction d is larger, the required regenerative torque Tr increases compared to when the degree of reduction d is smaller. In the present embodiment, the controller 31 increases the required regenerative torque Tr over time according to the degree of reduction d of the accelerator operation amount. As the degree of reduction d increases, the required regenerative torque Tr increased per unit time increases. When the required regenerative torque Tr reaches a predetermined upper limit value, the required regenerative torque Tr is maintained at the upper limit value. In the present embodiment, the predetermined upper limit value corresponds to the strong regenerative torque T2 obtained with reference to the strong regenerative torque map M2 as described later. That is, in the present embodiment, the upper limit value may vary with changes in the accelerator operation amount and the rotational speed of the electric motor 6 (see also Figure 3 ).

[0056] The controller 31 determines whether the predetermined regeneration reduction condition is satisfied while the required regeneration torque Tr is maintained at the upper limit value or while the required regeneration torque Tr increases based on the reduction degree d of the accelerator operation amount. In the present embodiment, the regeneration reduction condition corresponds to the condition that the regeneration time t reaches the set time ts described later.

[0057] When the controller 31 determines that the regeneration reduction condition is satisfied, the controller 31 reduces the required regeneration torque Tr as time passes. When the required regeneration torque Tr reaches a predetermined lower limit value, the controller 31 maintains the required regeneration torque Tr at the lower limit value. In the present embodiment, the predetermined lower limit value corresponds to the normal regeneration torque T1 obtained with reference to the normal torque map M1b as described later. That is, in the present embodiment, the lower limit value may vary with changes in the accelerator operation amount and the rotation speed of the electric motor 6 (see Figure 3 Graph of a single-point chain line in ).

[0058] Details of regeneration control

[0059] Figure 5 1 is a flowchart showing the process of regeneration control. First, the controller 31 counts the elapsed time from the start time point of the regeneration control, that is, the elapsed time t from the time point when the regeneration start condition is satisfied (step S11). In the following description, the elapsed time t from the time point when the regeneration start condition is satisfied is referred to as the regeneration time t.

[0060] The controller 31, more specifically, the torque determination unit 44 calculates the degree d of reduction of the accelerator operation amount over time before the start of the regeneration control, that is, before the time point when the regeneration start condition is satisfied (step S12). The degree of reduction d of the accelerator operation amount is used to determine the regeneration torque Tr required during a predetermined period from the start of the regeneration control. The predetermined period is a period from the start of the regeneration control to the time when the coefficient k described later reaches 0.

[0061] Figure 6 is a graph showing an example of a method of calculating the reduction degree d. Figure 6 The graph indicated by a solid line in FIG. 1 is a graph showing time series data of the accelerator operation amount received from the accelerator sensor 21 , and the horizontal axis indicates the time axis, and the vertical axis indicates the accelerator operation amount as the accelerator operation amount. Figure 6The dotted line in is obtained by performing low-pass filtering on the time series data of the accelerator operation amount received from the accelerator sensor 21. The time series data of the accelerator operation amount received from the accelerator sensor 21 is referred to as "unfiltered data", and the data obtained by performing low-pass filtering on the time series data of the accelerator operation amount received from the accelerator sensor 21 is referred to as "filtered data".

[0062] Since the filtered data is subjected to low-pass filtering, the filtered data changes later than the unfiltered data. In this embodiment, the controller 31 sets the difference of the accelerator operation amount obtained by subtracting the value of the unfiltered data at the start of the regeneration control from the value of the filtered data at the start of the regeneration control as the reduction degree d.

[0063] However, the reduction degree d may not be the difference between the value of the filtered data and the value of the simultaneously unfiltered data. For example, the reduction degree d may be the difference in the accelerator operation amount obtained by subtracting the value of the unfiltered data at the start of the regeneration control from the value of the filtered data before a predetermined time (e.g., the control cycle of the controller 31) from the start of the regeneration control.

[0064] Back to Figure 5 , the controller 31, more specifically, the torque determination unit 44 initializes the coefficient k to 0 (step S13). The coefficient k can take a value of 0 or more and a value of 1 or less. As will be described later, in the regeneration control according to the present embodiment, the coefficient k changes from 0 to 1 over time, and the required regeneration torque Tr required by the electric motor 6 is calculated using the coefficient k.

[0065] The controller 31, more specifically, the normal torque acquisition unit 41 uses the normal torque map to acquire the normal torque T1 corresponding to the accelerator operation amount and the electric motor rotation speed (step S14). The controller 31, more specifically, the strong regenerative torque acquisition unit 42 uses the strong regenerative torque map to acquire the strong regenerative torque T2 corresponding to the accelerator operation amount and the electric motor rotation speed (step S15).

[0066] The controller 31, more specifically, the strong regeneration selection unit 43 determines whether the regeneration time t is less than the set time ts (step S16). When it is determined that the regeneration time t is less than the set time ts (step S16: "Yes" (YES)), the controller 31 determines whether the coefficient k has reached 1 (step S17). When the coefficient k has not reached 1 (step S17: "No" (NO)), the controller 31 increases the coefficient k at a change rate corresponding to the reduction degree d obtained in step S12 (step S18), and proceeds to step S21.

[0067] In the memory of the controller 31, correspondence information indicating the correspondence between the reduction degree d and the rate of change of the coefficient k is stored in advance. The rate of change of the coefficient k is the amount of increase of the coefficient k per unit time. Referring to the correspondence information stored in the memory, the controller 31 acquires the rate of change corresponding to the acquired reduction degree d, and increases the coefficient k at the acquired rate of change. The reduction degree d and the rate of change of the coefficient k have a relationship in which the rate of change of the coefficient k (time increase rate) increases as the reduction degree d increases.

[0068] When the regeneration time t is less than the set time ts, the correspondence information indicating the correspondence between the reduction degree d and the rate of change of the coefficient k may be information indicating the relationship of the rate of change of the coefficient k obtained by multiplying the reduction degree d by the predetermined positive value α1. That is, the coefficient k may increase by a value of α1×d per unit time. In this case, the coefficient k may be calculated by multiplying the predetermined positive value α1, the reduction degree d, and the regeneration time t, that is, it may be calculated by the following calculation formula (1).

[0069] k=α1·d·t...(1)

[0070] When the coefficient k has reached 1 in step S17 (step S17: YES), the controller 31 maintains the coefficient k at 1 without changing the coefficient k, and proceeds to step S21.

[0071] When it is determined at step S16 that the regeneration time t is not less than the set time ts (step S16: "No" (NO)), the controller 31 determines whether the coefficient k has reached 0 (step S19). When the coefficient k has not reached 0 (step S19: "No" (NO)), the controller 31 decreases the coefficient k (step S20) and proceeds to step S21.

[0072] In step S20, the coefficient k may decrease over time based on the degree of reduction d. In this case, correspondence information indicating the correspondence between the degree of reduction d and the rate of change of the coefficient k when the regeneration time t exceeds the set time ts may also be pre-stored in the memory of the controller 31. The rate of change of the coefficient k may be information indicating the relationship obtained by multiplying the degree of reduction d by a predetermined negative value (-α2). That is, the coefficient k may be reduced by a value of α2×d per unit time. In this case, the coefficient k may be calculated by multiplying a predetermined negative value (-α2), the degree of reduction d, and the elapsed time (t-ts) from the set time ts, that is, it may be calculated by the following calculation formula (2).

[0073] k=-α2·d· (t-ts)... (2)

[0074] When the coefficient k has reached 0 in step S19 (step S19: YES), the controller 31 maintains the coefficient k at 0 without changing the coefficient k, and proceeds to step S21.

[0075] The controller 31, more specifically, the torque determination unit 44 uses the coefficient k obtained through steps S16, S17, S18, S19 and S20, the normal torque T1 obtained in step S14 and the strong regeneration torque T2 obtained in step S15 to calculate the required torque Tr by using the following formula (3), and outputs the control command to the inverter 32 (step S21).

[0076] Tr= (1-k)·T1+K·T2... (3)

[0077] That is, the value obtained by multiplying the normal regeneration torque T1 by the coefficient (1-k) and the value obtained by adding the value obtained by multiplying the strong regeneration torque T2 by the coefficient k are set as the required regeneration torque Tr. In this way, the required torque Tr is calculated using the normal torque T1 and the strong regeneration torque T2. In addition, the above formula (3) indicates that the ratio of the strong regeneration torque T2 to the required torque Tr increases as the coefficient k increases. In other words, the above formula (3) indicates that the magnitude (i.e., the absolute value) of the required regeneration torque Tr increases as the coefficient k increases.

[0078] The controller 31, more specifically, the torque determination unit 44 receives the accelerator operation amount from the accelerator sensor 21 and the motor rotation speed from the rotation speed sensor 22 (step S22). The controller 31 determines whether the regeneration end condition is satisfied (step S23). The regeneration end condition may be set to a condition that the normal torque T1 becomes a positive value, or may be set to a condition that the accelerator operation amount exceeds a predetermined value (for example, the accelerator operation amount is 5%). The regeneration end condition may be other conditions. For example, the regeneration end condition may be a user operation such as a brake operation or a clutch operation.

[0079] When it is determined that the regeneration end condition is not satisfied (step S23: "NO"), the process returns to step S14. Therefore, when it is determined in step S23 that the regeneration end condition is not satisfied, the steps from step S14 to step S23 are repeated to cause the electric motor 6 to generate a regeneration torque corresponding to the required regeneration torque Tr.

[0080] When determining that the regeneration end condition is satisfied (step S23: YES), the controller 31 switches the travel control from the regeneration control to the power running control.

[0081] The coefficient k changes according to the reduction degree d

[0082] Figure 7An example of how the coefficient k changes over time is shown. Figure 7 In , the horizontal axis indicates the regeneration time t, which is the time elapsed from the time point when the regeneration start condition is satisfied, and the vertical axis indicates the coefficient k. Figure 7 , an example of the change in the coefficient k when a relatively large reduction degree d is obtained is indicated by a solid line, and an example of the change in the coefficient k when a relatively small reduction degree d is obtained is indicated by a dotted line.

[0083] First, the change of the coefficient k when the reduction degree d is relatively large will be described. Figure 7 As shown in the solid line graph, when the regeneration start condition is satisfied, as time passes from the regeneration time t=0, the coefficient k increases at a rate corresponding to the reduction degree d (see Figure 5 As described above, the change rate is obtained from the correspondence information indicating the correspondence between the reduction degree d and the change rate of the coefficient k stored in the memory of the controller 31. Figure 7 , the rate of change corresponding to the reduction degree d corresponds to the slope of the solid line graph from the time point of the regeneration time t=0 to the time point of the regeneration time t=t1.

[0084] like Figure 7 As shown in the solid line graph, when the coefficient k reaches 1 at the time point of the regeneration time t=t1, the coefficient k is maintained at 1 until the regeneration time t reaches the set time ts (see Figure 5 While the coefficient k is maintained at 1, the required torque Tr becomes the strong regenerative torque T2 according to the above formula (3).

[0085] like Figure 7 As shown in the solid line graph, when the regeneration time t reaches the set time ts, the coefficient k decreases at a constant rate of change over time (see Figure 5 In step S20 in the embodiment, the strong regeneration end time t2 is preset. The strong regeneration end time t2 is a fixed value. The coefficient k decreases at a constant rate of change over time and reaches 0 at the strong regeneration end time t2. After the coefficient k reaches 0, the required torque Tr becomes the normal regeneration torque T1.

[0086] Next, the change of the coefficient k when the reduction degree d is relatively small will be described. Figure 7As in the dashed line graph, the coefficient k increases at a change rate corresponding to the reduction degree d as time passes from the time point of the regeneration time t=0, but the slope of the dashed line graph is smaller than the slope of the solid line graph during the period from the time point of the regeneration time t=0 to the time point of the regeneration time t=t1. This is because, in the correspondence information indicating the correspondence between the reduction degree d and the change rate of the coefficient k, the change rate of the coefficient k increases as the reduction degree d increases.

[0087] exist Figure 7 In the middle dashed line graph, the regeneration time t reaches the set time ts and the coefficient k does not reach 1. When the regeneration time t reaches the set time ts, the coefficient k decreases at a constant rate of change over time and reaches 0 when the regeneration time t reaches the strong regeneration end time t2. After the coefficient k reaches 0, the required torque Tr becomes the normal regeneration torque T1.

[0088] Operation and Effect

[0089] As described above, according to the present embodiment, the controller 31 obtains the degree d of decrease of the accelerator operation amount over time before the regeneration control starts, and determines the required regeneration torque Tr, which is the regeneration torque required by the electric motor 6, based on the degree d of decrease of the accelerator operation amount. Therefore, the regeneration torque varies according to the accelerator operation of the user. Since the braking force corresponding to the user's operation can be generated when the regeneration control is executed, the braking feeling felt by the user can be made close to the feeling expected by the user.

[0090] In this embodiment, the strong regenerative torque map is used at least for a predetermined period from the start of the regenerative control. The required regenerative torque Tr is determined based on the degree of reduction d of the accelerator operation amount for at least a predetermined period from the start of the regenerative control. Therefore, the braking feeling immediately after the start of the regenerative control can be made close to the feeling expected by the user.

[0091] In the present embodiment, as described above, the correspondence information stored in the memory is set so that the time increase rate of the coefficient k increases with the increase of the reduction degree d. In addition, the required regeneration torque Tr is determined using the formula (3) in which the absolute value of the required regeneration torque Tr increases with the increase of the coefficient k. That is, the required regeneration torque Tr increases with the increase of the reduction degree d of the accelerator operation amount. Therefore, the braking feeling felt by the user when performing the regeneration control can be close to the braking feeling when the engine brake in the engine vehicle is operated. Therefore, it is easy to prevent users who are familiar with the driving of the engine vehicle from feeling uncomfortable.

[0092] In the present embodiment, the coefficient k is increased in step S18 from the start of the regeneration control to the time point at which the condition for the coefficient k to reach 1 is satisfied. Therefore, since the required regeneration torque Tr increases with the elapse of time from the start of the regeneration control to the time point at which the predetermined condition is satisfied, the shock generated in the vehicle body can be reduced compared to the case where the regeneration torque changes abruptly.

[0093] In this embodiment, the rate of change of the coefficient k increases as the degree of decrease d of the accelerator operation amount increases. Therefore, since the increase in the required regenerative torque Tr per unit time increases as the degree of decrease d of the accelerator operation amount increases, the braking feeling can be made close to the braking feeling when the engine brake in an engine vehicle is operated, and it is easy to prevent users who are familiar with driving engine vehicles from feeling uncomfortable.

[0094] In the present embodiment, when the coefficient k reaches 1, the coefficient k is maintained at 1. That is, the required regenerative torque Tr is maintained at the strong regenerative torque T2 as the upper limit value. Since the upper limit value of the regenerative torque is set in this way, it is possible to prevent the braking force caused by the regenerative torque from becoming too large. Since the upper limit value varies depending on the rotation speed of the electric motor 6, the regenerative torque of the electric motor 6 can be limited to a range suitable for the rotation speed.

[0095] In this embodiment, after the regeneration time t reaches the set time ts, that is, after it is determined that the regeneration reduction condition is satisfied, the regeneration torque decreases over time, and therefore the shock generated in the vehicle body can be reduced compared to the case where the regeneration torque is suddenly reduced.

[0096] In the present embodiment, the absolute value of the required regenerative torque Tr determined during the predetermined period from the start of the regenerative control is greater than the absolute value of the required regenerative torque Tr determined after the predetermined period has passed. Therefore, it is possible to apply a relatively large regenerative torque from the start of the regenerative control to the predetermined period, and to generate a braking feeling according to the user's deceleration intention.

[0097] In the present embodiment, a coefficient k (where 0≤k≤1) is determined to increase with the passage of time as the degree of reduction of the accelerator operation amount increases, and the regeneration torque is determined by adding a value obtained by multiplying the normal regeneration torque by the coefficient (1-k) and a value obtained by multiplying the strong regeneration torque by the coefficient k. Therefore, with simple control logic, the regeneration torque can be increased as the degree of reduction of the accelerator operation amount increases.

[0098] Other embodiments

[0099] The present disclosure is not limited to the embodiments described above, and the configuration may be changed, added, or deleted.

[0100] For example, the vehicle described in the above embodiment is an electric vehicle including one driving source for traveling, but the vehicle is not limited thereto. For example, the vehicle may be a hybrid vehicle including two driving sources for traveling, an electric motor and an internal combustion engine. That is, the regeneration control method according to the present disclosure is also applicable to hybrid vehicles. In the hybrid vehicle, the above-mentioned regeneration control may be performed during driving driven by a motor. In addition, the straddle-type vehicle may not be a two-wheeled vehicle but may be a three-wheeled vehicle. In addition, the vehicle may not be a straddle-type vehicle and may be, for example, a four-wheeled vehicle. The vehicle may include a transmission device for switching the transmission ratio of the transmission device. The regeneration control method according to the present disclosure is applicable to all vehicles. In addition, the regeneration control method according to the present disclosure may be appropriately applied to a straddle-type vehicle, which has a relatively light weight compared to a four-wheeled vehicle and has a greater influence on the feel through regeneration control.

[0101] In the above embodiment, the regeneration start condition is a condition determined using the accelerator operation amount, the motor rotation speed, and the normal torque map, but the regeneration start condition is not limited thereto. For example, the regeneration start condition may be a condition that the accelerator operation amount is zero or equal to or less than a predetermined value (for example, the accelerator operation amount is 5%). In the above embodiment, the start condition of the regeneration control is determined based on the accelerator operation amount, but the start condition of the regeneration control may be determined based on a condition other than the accelerator operation amount. For example, the start condition of the regeneration control may include a condition that a braking operation is performed on a brake operator.

[0102] In the case where the vehicle includes a transmission device that switches the transmission ratio of the transmission device according to the user's shift operation, the start condition of the regeneration control may include the condition that the user's shift operation is a predetermined operation. In this way, the start of the regeneration control can be determined based on the user's operation. In addition, the start condition of the regeneration control can be determined based on multiple user operations such as the accelerator operation amount, the brake operation amount, and the shift operation amount. In addition, the regeneration start condition can be corrected or changed based on the vehicle state such as the vehicle speed, the motor rotation speed and the transmission ratio of the transmission device. For example, the regeneration start condition can be set so that the regeneration control starts earlier as the vehicle speed or the electric motor rotation speed is higher. Whether the regeneration control is necessary can be determined based on the state of the battery. The regeneration start condition can be set so that the start of the regeneration control is prevented when it is determined that the battery or circuit is damaged, for example, when the state of charge (SOC) of the battery is large or when the temperature of the wire is too high.

[0103] In the above embodiment, the regeneration reduction condition is the condition that the regeneration time t reaches the set time ts, but the regeneration reduction condition is not limited thereto. For example, the regeneration reduction condition may be either the condition that the regeneration time t reaches the set time ts or the condition that the coefficient k reaches 1. In addition, the regeneration reduction condition may be set according to the vehicle speed or the motor rotation speed.

[0104] In the above embodiment, the strong regeneration torque diagram is used during the strong regeneration end time t2 (i.e., a predetermined period from the start of regeneration control). The strong regeneration end time t2 is a preset fixed value, but the predetermined period is not limited thereto. The strong regeneration end time t2 may be a variable value. For example, the strong regeneration end time t2 may be set to increase as the degree of reduction d increases. Alternatively, the strong regeneration end time t2 may be set to increase as the magnitude of the coefficient k at the time point when the regeneration time t reaches the set time ts increases. The rate of change of the coefficient k with the passage of time after the regeneration time t reaches the set time ts may be a fixed value, and therefore the strong regeneration end time t2 may depend on the magnitude of the coefficient k at the time point when the regeneration time t reaches the set time ts.

[0105] In the above embodiment, two torque maps of the strong regeneration torque map and the normal torque map are used, and the coefficient k, which is the ratio of the strong regeneration torque T2 to the required torque Tr, increases with the lapse of time of the increase of the reduction degree d, so that the required regeneration torque increases with the increase of the reduction degree d. The method for determining the required regeneration torque that increases with the increase of the reduction degree d is not limited to this.

[0106] For example, in the above-described embodiment, both the strong regeneration torque map and the normal torque map are used for the predetermined period from the start of the regeneration control, but only the normal torque map may be used. In this case, the normal regeneration torque may be obtained from the normal torque map, and a value obtained by adding an additional torque corresponding to the magnitude of the reduction degree d to the normal regeneration torque obtained from the normal torque map during the predetermined period from the start of the regeneration control may be set as the required regeneration torque. Alternatively, a value obtained by multiplying the normal regeneration torque obtained from the normal torque map by a magnitude corresponding to the reduction degree d (however, a value of 1 or more) may be set as the required regeneration torque.

[0107] For example, in the above embodiment, both the strong regeneration torque map and the normal torque map are used for a predetermined period from the start of regeneration control, but only the strong regeneration torque map may be used, and in this case, the value obtained with reference to the strong regeneration torque map may be used as the required regeneration torque.

[0108] For example, in the above-mentioned embodiment, two types of regenerative torques (i.e., normal regenerative torque and strong regenerative torque) are obtained using two torque maps of a strong regenerative torque map and a normal torque map, but the normal regenerative torque and the strong regenerative torque may be obtained by methods other than the torque maps. The normal regenerative torque and the strong regenerative torque may be calculated by different calculation formulas (such as different coefficients) from each other.

[0109] In the above-mentioned embodiment, the normal torque diagram and the strong regeneration torque diagram show the correspondence between the accelerator operation amount and the motor rotation speed, and the torque, but the normal torque diagram and the strong regeneration torque diagram are not limited thereto. In the normal torque diagram and the strong regeneration torque diagram, only one or both of the normal torque diagram and the strong regeneration torque diagram may indicate the correspondence between the torque and only one of the accelerator operation amount and the motor rotation speed.

[0110] In the above embodiment, the required regenerative torque Tr is maintained not to exceed a predetermined upper limit value, and the upper limit value corresponds to the strong regenerative torque T2 obtained by referring to the strong regenerative torque map M2, but the upper limit value is not limited thereto. The upper limit value may not change according to the accelerator operation amount or the motor rotation speed. For example, the upper limit value may be a pre-set fixed value.

[0111] In the regeneration control according to the above-mentioned embodiment, obtaining the degree of reduction of the accelerator operation amount as time passes before the regeneration control starts includes performing low-pass filtering on the obtained accelerator operation amount, and calculating the degree of reduction of the accelerator operation amount by subtracting the obtained accelerator operation amount from the accelerator operation amount after the low-pass filtering. However, the method of obtaining the degree of reduction is not limited to this. In the above-mentioned embodiment, as shown in reference Figure 6 As described above, the degree of reduction d is the difference in the accelerator operation amount obtained by subtracting the value of the unfiltered data at the start of the regeneration control from the value of the filtered data at the start of the regeneration control, but the degree of reduction may be a value related to the time rate of change of the accelerator operation amount, and other indicators indicating the degree of reduction in the accelerator operation amount may be used.

[0112] For example, the degree of reduction of the accelerator operation amount can be calculated from the difference between the accelerator operation amount at the start of the regeneration control and the accelerator operation amount acquired at a predetermined time before the start of the regeneration control. However, in this case, when the predetermined time is set to a relatively small value, only the user's operation immediately before the regeneration control start time point is reflected in the degree of reduction of the accelerator operation amount. Therefore, for example, between the case where an operation of suddenly closing the accelerator operation amount is performed from a state where the accelerator operation amount is fully open (100%) and the case where an operation of suddenly closing the accelerator operation amount is performed from a state where the accelerator operation amount is 20%, the difference in the calculated degree of reduction is unlikely to occur. On the other hand, when the predetermined time is set to a relatively large value, the user's operation performed during the predetermined time is not reflected in the degree of reduction of the accelerator operation amount. For example, between the case where an operation for slowly reducing the accelerator operation amount by a predetermined time is performed from a time point before the start of the regeneration control and the case where an operation for temporarily increasing the accelerator operation amount by a predetermined time and then reducing the accelerator operation amount is performed from a time point before the start of the regeneration control, the difference in the calculated degree of reduction is unlikely to occur. For this reason, from the viewpoint that the user's operation is easily reflected in the acquired decrease degree of the accelerator operation amount, it is preferable to calculate the decrease degree of the accelerator operation amount by subtracting the acquired accelerator operation amount from the low-pass filtered accelerator operation amount.

[0113] In the above-described embodiment, when the coefficient k is gradually changed, the coefficient k changes linearly so that Figure 7 The amount per unit time shown is increased by a certain amount, but the coefficient k can be changed nonlinearly or stepwise. In addition, the coefficient k can be changed instantaneously rather than gradually.

[0114] In the above embodiment, the required torque Tr is calculated by formula (3), but the calculation formula of the required torque Tr is only an example. The required torque Tr can be determined by another method. In this case as well, it is preferred to increase the regenerative torque as the degree of reduction of the accelerator operation amount increases in the initial stage at the start of regeneration. In addition, in the present embodiment, as the degree of reduction of the accelerator operation amount increases, the increase in the regenerative torque (the time rate of change of the regenerative torque) as the regenerative torque increases over time from the start of regeneration increases. For example, the greater the degree of reduction of the accelerator operation amount, the greater the maximum value of the regenerative torque, and the time rate of change of the regenerative torque can be the same regardless of the degree of reduction of the accelerator operation amount. For example, the required regenerative torque can be determined to become the maximum regenerative torque at the start of regeneration, rather than gradually increasing at the start of regeneration. In this case as well, it is preferred that the maximum regenerative torque is determined to increase as the degree of reduction of the accelerator operation amount increases.

[0115] In the above-described embodiment, the strong regenerative torque is set based on the motor rotation speed and the accelerator operation amount, but the strong regenerative torque is not limited thereto, and the strong regenerative torque may be a value that produces a large regenerative amount relative to the regenerative amount of the normal torque map. Since the strong regenerative torque having a value different from the regenerative torque obtained by the normal torque map is set based on the electric motor rotation speed and the accelerator operation amount, it is possible to easily obtain a regenerative torque that is different depending on the situation, and to easily approach a braking feeling preferred by the user.

[0116] Although the battery is detachable in the above embodiment, the battery may not be detachable. The electric motor may not be arranged between the front wheel and the rear wheel. For example, the electric motor may be an in-wheel motor. The electric motor may be arranged on a swing arm that pivotally supports the rear wheel. In the above embodiment, the electric motor is exemplified by an AC motor, but it may also be a DC motor. The vehicle may include a drive motor and a brake motor separately. The vehicle body frame supporting the electric motor and the battery may be appropriately changed.

[0117] The meter device 8 may display information indicating a regeneration control state in which the regeneration control is performed. In this case, the controller 31 transmits a command for displaying the regeneration control state to the meter device 8. In addition, when displaying the regeneration control state, the meter device 8 may make the display mode different between a state in which the regeneration braking is strong and a state in which the regeneration braking is weak. In this case, the controller 31 transmits information indicating whether the regeneration braking is strong or weak to the meter device 8.

[0118] The functions of the elements disclosed in this specification can be performed by using a general-purpose processor, a special-purpose processor, an integrated circuit, an application-specific integrated circuit (ASIC), a conventional circuit, a circuit, or a processing circuit including any combination thereof, which is configured or programmed to perform the disclosed functions. Since the processor includes transistors and other circuits, the processor is considered to be a processing circuit or circuit. In the present disclosure, circuits, units and devices are hardware for performing the listed functions or hardware programmed to perform the listed functions. The hardware can be hardware disclosed in this specification, or it can be a program or other known hardware configured to perform the listed functions. When the hardware is a processor that is considered as a circuit, the circuit, device or unit is a combination of hardware and software, and the software is used for the configuration of the hardware or processor.

[0119] The program including instructions for executing the method of the present disclosure may be stored in a non-transitory computer-readable storage medium. The non-transitory computer-readable storage medium includes, for example, a disk such as a hard drive, an optical disk such as a CD-ROM, a DVD, and a Blu-ray disk, a read-only memory (ROM), a random access memory (RAM), an EPROM, an EEPROM, a magnetic card, a flash memory, an optical card, and any type of medium suitable for storing electronic commands.

[0120] Public Aspects

[0121] The following aspects each disclose a preferred embodiment.

[0122] According to a first aspect of the present disclosure, a regenerative control method for a vehicle, which is executed in a processing circuit of a vehicle including an electric motor as a drive source, includes: determining whether a starting condition for regenerative control for requesting the electric motor to generate a regenerative torque is satisfied; before the regenerative control starts, obtaining the degree to which an accelerator operation amount decreases over time; and determining a required regenerative torque based on the degree of decrease in the accelerator operation amount, the required regenerative torque being the regenerative torque required by the electric motor.

[0123] According to this method, the regenerative torque varies according to the user's accelerator operation. Since a braking force corresponding to the user's operation can be generated when the regenerative control is executed, the braking feeling felt by the user can be made close to the feeling expected by the user.

[0124] According to a second aspect of the present disclosure, in the regeneration control method for a vehicle according to aspect 1, the determination of the required regeneration torque based on the degree of reduction of the accelerator operation amount is performed within a predetermined period from the start of the regeneration control.

[0125] According to this method, since the required regenerative torque is determined based on the degree of reduction in the accelerator operation amount during at least a predetermined period from the start of the regenerative control, the braking feeling immediately after the start of the regenerative control can be made close to the feeling expected by the user.

[0126] According to a third aspect of the present disclosure, in the regeneration control method for a vehicle according to aspect 1 or 2, determining the required regeneration torque based on the degree of reduction in the accelerator operation amount includes increasing the required regeneration torque as the degree of reduction in the accelerator operation amount increases.

[0127] According to this method, since the regenerative torque increases as the degree of reduction of the accelerator operation amount increases, the braking feeling felt by the user when the regenerative control is performed can be made close to the braking feeling when the engine brake in the engine vehicle is operated. Therefore, it is easy to prevent the user who is familiar with the driving of the engine vehicle from feeling uncomfortable.

[0128] According to a fourth aspect of the present disclosure, in a regeneration control method for a vehicle according to any one of aspects 1 to 3, determining the required regeneration torque based on the degree of reduction in the accelerator operation amount includes increasing the required regeneration torque as time passes from the start of the regeneration control to a time point when a predetermined condition is satisfied.

[0129] According to this method, since the regenerative torque generated by the electric motor increases with the lapse of time, it is possible to reduce the shock generated in the vehicle body compared to a case where the regenerative torque changes suddenly.

[0130] According to a fifth aspect of the present disclosure, in the regeneration control method for a vehicle according to aspect 4, increasing the required regeneration torque includes increasing an increase amount per unit time of the required regeneration torque as a degree of decrease in the accelerator operation amount increases.

[0131] According to this method, since the increase in the required regenerative torque per unit time increases with the degree of reduction in the accelerator operation amount, the braking feel can be made close to the braking feel when the engine brake in an engine vehicle is operated, and it is easy to prevent users who are familiar with driving engine vehicles from feeling uncomfortable.

[0132] According to the sixth aspect of the present disclosure, in the regeneration control method for a vehicle according to any one of aspects 1 to 5, determining the required regeneration torque based on the degree of reduction in the accelerator operation amount includes: increasing the required regeneration torque over time based on the degree of reduction in the accelerator operation amount; maintaining the required regeneration torque at a predetermined upper limit value when the required regeneration torque reaches the upper limit value; determining whether a predetermined regeneration reduction condition is met; and reducing the required regeneration torque when it is determined that the regeneration reduction condition is met.

[0133] According to this method, since the upper limit value of the regenerative torque is set, it is possible to prevent the braking force due to the regenerative torque from becoming excessive.

[0134] According to a seventh aspect of the present disclosure, in the regeneration control method for a vehicle according to aspect 6, the upper limit value varies according to a rotation speed of the electric motor.

[0135] According to this method, since the upper limit value of the regenerative torque is changed according to the motor rotation speed, the regenerative torque of the electric motor can be limited within a range suitable for the rotation speed.

[0136] According to the eighth aspect of the present disclosure, in the regeneration control method for a vehicle described in any one of aspects 1 to 3, determining the required regeneration torque based on the degree of reduction in the accelerator operation amount includes: changing the required regeneration torque over time based on the degree of reduction in the accelerator operation amount; determining whether a predetermined regeneration reduction condition is met; and when it is determined that the regeneration reduction condition is met, reducing the regeneration torque over time after or at the same time as changing the required regeneration torque based on the degree of reduction in the accelerator operation amount.

[0137] According to this method, since the regeneration torque is reduced with the elapse of time after it is determined that the regeneration reduction condition is satisfied, the shock generated in the vehicle body can be reduced compared to a case where the regeneration torque is suddenly reduced.

[0138] According to a ninth aspect of the present disclosure, a regeneration control method for a vehicle, which is executed in a processing circuit of a vehicle including an electric motor as a drive source, includes: determining whether a start condition of regeneration control for requesting the electric motor to generate a regeneration torque is satisfied; and after determining that the start condition is satisfied, determining a required regeneration torque, the required regeneration torque being a regeneration torque required by the electric motor. An absolute value of the required regeneration torque determined in a predetermined period from the start of the regeneration control is greater than an absolute value of the required regeneration torque determined after the predetermined period has passed.

[0139] According to this method, it is possible to apply a relatively large regenerative torque from the regenerative control for a predetermined period of time and generate a braking feeling according to the user's deceleration intention.

[0140] According to a tenth aspect of the present disclosure, a straddle-type vehicle includes: an accelerator operator operated by a user; a drive wheel; an electric motor as a drive source for driving the drive wheel; and a processing circuit configured to control the regenerative torque of the electric motor for braking the drive wheel. The processing circuit is configured to: determine whether a start condition for regenerative control for requesting the electric motor to generate a regenerative torque is satisfied; before the regenerative control is started, obtain the degree of decrease of the accelerator operation amount over time; and determine a required regenerative torque based on the degree of decrease of the accelerator operation amount, the required regenerative torque being the regenerative torque required by the electric motor.

Claims

1. A regeneration control method for a vehicle, the regeneration control method being executed in a processing circuit of a vehicle including an electric motor as a driving source, the regeneration control method include: determining whether a start condition of regeneration control for requesting the electric motor to generate regeneration torque is satisfied; Before the regeneration control starts, obtaining a degree of decrease in the accelerator operation amount with the passage of time; and A required regenerative torque is determined based on a degree of reduction in the accelerator operation amount, the required regenerative torque being a regenerative torque required for the electric motor.

2. The regeneration control method for a vehicle according to claim 1, in, Determination of the required regeneration torque based on the degree of reduction of the accelerator operation amount is performed within a predetermined period from the start of the regeneration control.

3. The regeneration control method for a vehicle according to claim 1 or 2, in, Determining the required regeneration torque based on the degree of reduction of the accelerator operation amount includes increasing the required regeneration torque as the degree of reduction of the accelerator operation amount increases.

4. The regeneration control method for a vehicle according to claim 1 or 2, in, Determining the required regeneration torque based on the degree of reduction in the accelerator operation amount includes increasing the required regeneration torque as time elapses from the start of the regeneration control to a point in time when a predetermined condition is satisfied.

5. The regeneration control method for a vehicle according to claim 4, in, Increasing the required regeneration torque includes increasing an increase amount per unit time of the required regeneration torque as the degree of decrease of the accelerator operation amount increases.

6. The regeneration control method for a vehicle according to claim 1 or 2, in, Determining the required regeneration torque based on the degree of reduction of the accelerator operation amount includes: increasing the required regenerative torque as the time elapses based on a degree of reduction in the accelerator operation amount; When the required regenerative torque reaches the upper limit value, maintaining the required regenerative torque at the predetermined upper limit value; determining whether predetermined regeneration reduction conditions are met; and The required regeneration torque is reduced when it is determined that the regeneration reduction condition is satisfied.

7. The regeneration control method for a vehicle according to claim 6, in, The upper limit value varies according to the rotation speed of the electric motor.

8. The regeneration control method for a vehicle according to claim 1 or 2, in, Determining the required regeneration torque based on the degree of reduction of the accelerator operation amount includes: changing the required regeneration torque as the time elapses based on a degree of reduction in the accelerator operation amount; determining whether predetermined regeneration reduction conditions are met; and When it is determined that the regeneration reduction condition is satisfied, the regeneration torque is reduced as the time elapses after or while the required regeneration torque is changed based on the degree of reduction in the accelerator operation amount.

9. A regeneration control method for a vehicle, the regeneration control method being executed in a processing circuit of a vehicle including an electric motor as a drive source, the regeneration control method include: determining whether a start condition of regeneration control for requesting the electric motor to generate regeneration torque is satisfied; as well as After determining that the start condition is satisfied, a required regenerative torque is determined, wherein the regenerative torque is the regenerative torque required by the electric motor, wherein: An absolute value of the required regeneration torque determined in a predetermined period from the start of the regeneration control is greater than an absolute value of the required regeneration torque determined after the predetermined period has elapsed. 10 . A non-transitory computer-readable medium storing a program for causing a processing circuit to execute the regeneration control method for a vehicle according to claim 1 or 2 .

11. A straddle-type vehicle, include: an accelerator operator operated by a user; Drive wheels; an electric motor serving as a driving source for driving the driving wheels; as well as a processing circuit configured to control a regenerative torque of an electric motor for braking the drive wheels, wherein: The processing circuit is configured to: determining whether a start condition of regeneration control for requesting the electric motor to generate the regeneration torque is satisfied; Before the regeneration control starts, obtaining a degree of decrease in the accelerator operation amount with the passage of time; and A required regenerative torque is determined based on a degree of reduction in the accelerator operation amount, the regenerative torque being a regenerative torque required for the electric motor.

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