Power-assisted bicycle and determination method of transmission gear ratio of power-assisted bicycle

Abstract

To provide a power-assisted bicycle and a determination method of a transmission gear ratio of the power-assisted bicycle of reducing a risk of erroneous determination of the transmission gear ratio and accurately determining the transmission gear ratio.SOLUTION: In a power-assisted bicycle (1), a time from when a first transmission gear ratio is changed to a second transmission gear ratio to when assist of a pedal (4) corresponding to the second transmission gear ratio starts is different from a time from when a third transmission gear ratio is changed to a fourth transmission gear ratio to when assist of the pedal (4) corresponding to the fourth transmission gear ratio starts.SELECTED DRAWING: Figure 4(a)

Description

Technical Field

[0001] The present invention relates to an electric assist bicycle and a method for determining the gear ratio of an electric assist bicycle.

Background Art

[0002] Patent Document 1 discloses a technique for appropriately controlling the assist ratio of an electric assist bicycle that has a transmission and a motor and in which the ratio of the driving rotational speed of the motor to the driving rotational speed of the pedal changes according to a change in the gear ratio of the transmission.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to determine the current gear ratio of an electric assist bicycle, it is necessary to measure the rotational speed of the motor and the rotational speed of the wheels. However, due to problems with the accuracy of the rotational speed sensor, a state may occur in which "it is not possible to tell which of the adjacent gear ratios is correct." For example, even when set to gear 3, it may not be possible to tell from the results of measuring the rotational speed of the motor and the rotational speed of the wheels whether it is set to gear 2 or gear 3. In this state, if it is erroneously determined that it is set to gear 2, the electric assist bicycle may behave unexpectedly.

[0005] Therefore, an example of the problem of the present invention is to reduce the risk of misjudgment by tentatively judging both of the adjacent gear ratios as candidates in the case of a state in which "it is not possible to tell which of the adjacent gear ratios is correct," and to accurately determine the gear ratio.

Means for Solving the Problems

[0006] In an electric assist bicycle which is an example of the present invention, the time from when the gear ratio is changed from the first gear ratio to the second gear ratio until the pedal assist corresponding to the second gear ratio is started is different from the time from when the gear ratio is changed from the third gear ratio to the fourth gear ratio until the pedal assist corresponding to the fourth gear ratio is started.

[0007] An electric assist bicycle which is an example of the present invention includes a control device. The time from when the stopped control device is activated until the pedal assist corresponding to the gear ratio is started is longer than the time from when the gear ratio is changed until the pedal assist corresponding to the changed gear ratio is started.

[0008] A method for determining the gear ratio of an electric assist bicycle which is an example of the present invention includes: a first step of determining a candidate for the predetermined gear ratio before the elapse of a first period after the gear ratio is changed to the predetermined gear ratio; a second step of determining the predetermined gear ratio from the candidates for the predetermined gear ratio after the elapse of the first period and before the elapse of a second period. It has.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4(a)

Figure 4(b)

Figure 5

Figure 6

Figure 7

Figure 8(a)

Figure 8(b)

Figure 8(c)

Mode for Carrying Out the Invention

[0010] FIG. 1 is a side view of an electric assist bicycle equipped with a control device (motor control drive device). The electric assist bicycle 1 includes a frame F, a handle H, a saddle S, a transmission body C, a battery B, a rotating device (MDU: motor drive unit) 100, a first wheel (front wheel) 2, a second wheel (rear wheel) 3, and a pedal 4. When the driver sits on the saddle S of the electric assist bicycle 1 and rotates the pedal 4 with their feet, a driving force is transmitted to the wheels (typically the rear wheel 3) via the transmission body C while receiving assistance from the rotating device 100 as necessary, enabling forward travel. The transmission body C may be a chain or a belt.

[0011] A first sensor 5 for detecting the rotational speed of the wheel is disposed, for example, near the rotation axis of the front wheel 2 or the rear wheel 3. Although FIG. 1 shows an example in which the first sensor 5 is disposed on the rear wheel 3, the first sensor 5 may be disposed at a position where it can detect the rotational speed or rotational angle of the wheel, for example, at a position away from the rotation axis of the front wheel 2 or the rear wheel 3. As the first sensor 5, a known sensor capable of detecting the rotational speed of the wheel can be used. The first sensor 5 is, for example, a magnetic sensor (Hall sensor).

[0012] The rotating device 100 and the battery B are typically arranged around a crankshaft (not shown) connected to the pedal 4. The rotating device 100 has a motor M and a speed reducer G (see FIG. 2). The battery B supplies power to the motor M and the control device 50, and the motor M and the control device 50 operate.

[0013] The motor M is controlled by the control device 50 and assists the rotation of the pedal 4 via the speed reducer G. In this specification, the "rotation of the pedal 4" refers to the rotation of the pedal 4 around the crankshaft. Also, in this specification, "assisting the rotation of the pedal 4" includes reducing the force (pedaling force) required to rotate the pedal 4 to move the bicycle forward. The motor M may be, for example, a brushless DC motor having coils corresponding to three phases (U phase, V phase, and W phase).

[0014] The second sensor 6 is a sensor that detects the rotational speed of the motor M, for example, a hall sensor, and is arranged near the motor M. Using a hall sensor to calculate the rotational speed of the chainring from the rotational speed of the motor M detected by this hall sensor can obtain the rotational speed of the chainring more accurately than using a cadence sensor attached near the crankshaft, and data at a desired time interval for use in software It is preferable in that the rotation speed can be obtained. The first reason why the rotation speed can be obtained more accurately by using a Hall sensor is that the Hall sensor is fixed so as to always be in the same position with respect to the rotor of the motor M, and thus can always obtain accurate magnetism. In contrast, for a cadence sensor, the distance between the magnet on the shaft connecting both pedals 4 and the magnetic sensor on the substrate slightly changes due to the influence of the shaft being distorted by the pedaling force. Further, as a second reason, the influence of the power of the rotating body to be detected can also be considered. That is, in the Hall sensor, the power of the motor M of the rotating body to be detected is electricity, while in the cadence sensor, the power of the pedal 4 of the rotating body to be detected is human power. For example, when the detection period is 1 ms, the fluctuation of electricity per detection period is smaller than that of human power, and it can be used as data in software.

[0015] FIG. 2 is a diagram showing a part of an electric assist bicycle. Generally in a bicycle, a difference in rotation speed occurs due to the difference in the selected number of gear teeth of a multi-stage (rear) gear sprocket 9 with respect to the number of gear teeth of the crank (front) 8. For example, in the present embodiment, the number of gear teeth of the crank 8 is 44, the gear sprocket 9 has 9 stages, and the number of its gear teeth is 11 - 13 - 15 - 17 - 20 - 23 - 26 - 30 - 36. As an example of the rear gear position, the first stage is the position with 36 gear teeth, the second stage is the position with 30 gear teeth, and the third stage is the position with 26 gear teeth. Gear 1 is the lightest and gear 9 is the heaviest. Table 1 shows the set values of the gears of the present embodiment. The table shown below including Table 1 is stored in the storage device of the control circuit 50a (see FIG. 3). The theoretical value of the rotation speed ratio R can be calculated by the number of rear gear teeth / the number of front gear teeth. In Table 1, only the third decimal place is described, but in actual calculation, the fourth decimal place and below are also used. In the present embodiment, the lower limit of the threshold value used for determination is 90% of the theoretical value of the rotation speed ratio, and the upper limit of the threshold value is 110% of the theoretical value of the rotation speed ratio. However, the upper and lower limits of the threshold value can be arbitrarily set.

[0016] [Table 1]

[0017] The actual rotation speed ratio R is N w is the rotation speed of rear wheel 3 [rpm], N m is the rotation speed [rpm] of the motor M, and gr MDU is the reduction ratio of the rotating device 100, it is expressed by the formula (1). R=N m / (gr MDU N w ) Formula (1) In the gear ratio state determination process described below, the control device 50 determines whether the rotation speed ratio R, i.e., the magnitude of equation (1), is included within a predetermined range (threshold range in Table 1) corresponding to each gear ratio.

[0018] FIG. 3 is a block diagram schematically showing the configuration of the control device, the first sensor, the second sensor, and the motor. The control device 50 has, for example, a control circuit 50a and a drive circuit 50b. The components of the control device 50 shown in Fig. 3 are only a part of the whole, and the control device 50 may have other components in addition to those shown in Fig. 3.

[0019] The control circuit 50a is realized by a program processing device (e.g., a microcontroller) having a configuration in which a processor such as a CPU, various storage devices such as RAM and ROM, and peripheral circuits such as a counter (timer), an A / D conversion circuit, a D / A conversion circuit, a clock generation circuit, and an input / output I / F circuit are connected to each other via a bus or dedicated lines.

[0020] The control circuit 50a has, for example, as functional blocks, a rotational speed calculation unit 51, an i comparison unit 52, a threshold comparison unit 53, a gear ratio setting unit 54, an i setting unit 55, a C setting unit 56, a count threshold comparison unit 57, and a drive control signal generation unit 58. The rotational speed calculation unit 51, the i comparison unit 52, the threshold comparison unit 53, the gear ratio setting unit 54, the i setting unit 55, the C setting unit 56, the count threshold comparison unit 57, and the drive control signal generation unit 58 are realized, for example, in a program processing device as the control circuit 50a by the processor executing various arithmetic processes according to a program stored in a memory and controlling peripheral circuits such as a counter and an A / D conversion circuit. Note that the control circuit 50a may have other functions.

[0021] Based on the drive command signal, the drive control signal generation unit 58 generates a drive control signal Sd for driving the motor M and controls the drive of the motor M. The drive control signal Sd is, for example, a PWM (Pulse Width Modulation) signal.

[0022] Based on the drive control signal Sd, the drive circuit 50b drives the motor M by exciting the coils corresponding to the three phases (U phase, V phase, and W phase) of the motor M. The drive circuit 50b may have, for example, an inverter circuit for driving each coil, a pre-drive circuit for driving the inverter circuit according to the drive control signal Sd, and a current detection circuit for detecting the current flowing through each coil.

[0023] The control device 50 may be configured such that part or all of the control circuit 50a and part or all of the drive circuit 50b are packaged as one integrated circuit device (IC), or the control circuit 50a and the drive circuit 50b may be packaged as individual integrated circuit devices, respectively.

[0024] The functions and operations of the rotational speed calculation unit 51, the i comparison unit 52, the threshold comparison unit 53, the gear ratio setting unit 54, the i setting unit 55, the C setting unit 56, and the count threshold comparison unit 57 will be described using the flowchart of the gear ratio state determination process described later.

[0025] Figure 4(a) is a flowchart for explaining the control in the present invention, and Figure 4(b) is a timing chart for explaining this control. In step S1, the control device 50 detects whether the gear ratio has been changed from the first gear ratio to the second gear ratio. Let the time point when the gear ratio is changed from the first gear ratio to the second gear ratio be t = t10. In step S2, the control device 50 performs a gear ratio state determination process described later. In step S3, the control device 50 controls so that the assist of the pedal corresponding to the second gear ratio is started. Let the time point when the assist of the pedal corresponding to the second gear ratio is started be t = t11. The time from when the gear ratio is changed from the first gear ratio to the second gear ratio until the assist of the pedal corresponding to the second gear ratio is started is (t11 - t10). Here, the process ends, but this process is performed every time the gear ratio is changed.

[0026] For example, if the time point when the gear ratio is changed from the third gear ratio to the fourth gear ratio is t = t12, and the time point when the assist of the pedal corresponding to the fourth gear ratio is started is t = t13, then the time from when the gear ratio is changed from the third gear ratio to the fourth gear ratio until the assist of the pedal corresponding to the fourth gear ratio is started is (t13 - t12). In the present invention, due to the gear ratio state determination process described later, the time (t11 - t10) from when the gear ratio is changed from the first gear ratio to the second gear ratio until the assist of the pedal corresponding to the second gear ratio is started is different from the time (t13 - t12) from when the gear ratio is changed from the third gear ratio to the fourth gear ratio until the assist of the pedal corresponding to the fourth gear ratio is started.

[0027] Figure 5 is a timing chart for explaining other control in the present invention. Consider the case where the control device 50 starts at time t = t20 from a stopped state. The pedal assist does not start simultaneously with the startup, but starts after a predetermined time. For example, at time t = t21, it is assumed that the pedal assist corresponding to the gear ratio set at startup starts. Consider the case where the gear ratio is changed at time t = t22 after a predetermined time has elapsed since the control device 50 started up. Similar to when the control device 50 starts up, the pedal assist at the changed gear ratio is not applied simultaneously with the change in the gear ratio, but is applied after a predetermined time. For example, at time t = t23, it is assumed that the pedal assist corresponding to the changed gear ratio starts. In the present invention, due to the gear ratio state determination process described later, the time (t21 - t20) from the startup of the stopped control device 50 until the pedal assist corresponding to the gear ratio starts is longer than the time (t23 - t22) from the change in the gear ratio until the pedal assist corresponding to the changed gear ratio starts.

[0028] Here, the time until the pedal assist corresponding to the gear ratio starts is preferably within the time required for one rotation of the wheel. Specifically, the times (t11 - t10), (t13 - t12), (t21 - t20), and (t23 - t22) are preferably within the time required for one rotation of the rear wheel 3.

[0029] FIG. 6 is a timing diagram for explaining other controls in the present invention. At time t = t30, it is assumed that the gear ratio is changed to a predetermined gear ratio. At time t = 31 before the elapse of the first period p1 after the change to the predetermined gear ratio, the control device 50 determines (temporarily determines) a candidate for the predetermined gear ratio by the gear ratio state determination process described later. For example, gears 2 and 3 are determined (temporarily determined) as candidates. At time t = 32 after the elapse of the first period p1 and before the elapse of the second period p2, the control device 50 determines the predetermined gear ratio from the candidates for the predetermined gear ratio by the gear ratio state determination process described later. For example, it is determined that gear 3 is the current gear ratio from the two candidates (gears 2 and 3).

[0030] Here, the period including the first period p1 and the second period p2 is preferably within the time taken for one rotation of the wheel (rear wheel 3).

[0031] In addition, in a certain electric assist bicycle, as a method for confirming whether it has the magnitude relationship of time (time lag) which is a characteristic matter of the present invention, checking a display (display device) that displays the gear position, checking that the assist output is suppressed until the gear position is determined, checking that a time lag occurs in the output of the assist due to the motor current, etc. can be considered.

[0032] Figure 7 is a flowchart for explaining the gear ratio state determination process. The current gear ratio is set to gear 3. However, as described above, from the results of measuring the rotational speed of the motor and the rotational speed of the wheel, there may be a case where it is not known whether it is set to gear 2 or gear 3. The state of "not knowing which of the adjacent gear ratios is correct" can occur, for example, when changing the gear ratio and when starting to pedal after starting the system (control device 50) from a stopped state. In the present invention, the gear ratio state determination process can preliminarily determine or confirm which gear it is in. As Example 1, the case where the ratio of the rotational speeds does not change at R = 0.63 is shown. As Example 2, the case where the ratio of the rotational speeds changes from R = 0.63 to R = 0.55 is shown. As Example 3, the case where the ratio of the rotational speeds changes from R = 0.55 to R = 0.63 is shown.

[0033] In Example 1, the ratio of the rotational speeds does not change at R = 0.63. Every time a vehicle speed pulse comes, the count values C of gear 2 and gear 3 increase. When the count value C exceeds the count threshold value, gear 2 and gear 3 become "preliminary determination". Hereinafter, it will be described in detail along the flowchart. In the present embodiment, as the first sensor 5, a sensor that outputs 12 pulses (hereinafter referred to as vehicle speed pulses) during one rotation of the wheel is used. ​

[0034] In step S11, the rotation speed calculation unit 51 receives a signal indicating the rotation speed of the wheel (rear wheel 3) from the first sensor 5, and detects the timing of changing the vehicle speed (whether a 1 / 12 vehicle speed pulse has arrived). Hereinafter, the timing of changing the vehicle speed is referred to as the vehicle speed change timing. At the vehicle speed change timing (when a 1 / 12 vehicle speed pulse arrives), in step S12, the rotation speed calculation unit 51 calculates the rotation speed ratio R according to the above-described formula (1) based on the signal from the first sensor 5 and the signal indicating the rotation speed of the motor from the second sensor 6. In the first embodiment, it is assumed that the rotation speed ratio R = 0.63.

[0035] In step S13, the i comparison unit 52 compares i with Ngear. The initial value of i is 1, and Ngear is the number of gear ratios (the number of stages of the gear sprocket), which is 9 in this embodiment. Here, since i < 9, the process proceeds to step S14. In step S14, the threshold comparison unit 53 checks whether the rotation speed ratio R = 0.63 is within the threshold range. From Table 1, the threshold for i = 1 is 0.736 to 0.900, and since the rotation speed ratio R = 0.63 is not within the threshold range, the process proceeds to step S15. In step S15, the gear ratio setting unit 54 checks whether the gear ratio state of gear 1 is "temporary determination" or "confirmation". As shown in Table 2, the initial value of the gear ratio state of all gears 1 to 9 is "undetermined", and the gear ratio state of gear 1 is also "undetermined", so the process proceeds to step S21.

Table 2

[0036] In step S13, the i comparison unit 52 compares i with Ngear. Since i = 2, the process proceeds to step S14. In step S14, the threshold comparison unit 53 checks whether the rotation speed ratio R = 0.63 is within the threshold range. From Table 1, the threshold for i = 2 is 0.614 to 0.750, and since the rotation speed ratio R = 0.63 is within the threshold range, the process proceeds to step S16. In step S16, the C setting unit 56 increments the count value C of gear 2. Specifically, the count value C of gear 2 in Table 3 is changed from 0 to 1. In the tables shown below, including Table 3, the parts changed in this step are * marked.

Table 3

[0037] In step S13, the i comparison unit 52 compares i with Ngear. Since i = 3, the process proceeds to step S14. In step S14, the threshold comparison unit 53 checks whether the rotation speed ratio R = 0.63 is within the threshold range. From Table 1, the threshold for i = 3 is 0.532 to 0.650, and since the rotation speed ratio R = 0.63 is within the threshold range, the process proceeds to step S16. In step S16, the C setting unit 56 increments the count value C of gear 3. Specifically, the count value C of gear 3 in Table 4 is changed from 0 to 1.

Table 4

[0038] In step S13, the i comparison unit 52 compares i with Ngear. Since i = 4, the process proceeds to step S14. In step S14, the threshold comparison unit 53 checks whether the rotation speed ratio R = 0.63 is within the threshold range. From Table 1, the threshold for i = 4 is 0.470 - 0.535, and the rotation speed ratio R = 0.63 is not within the threshold range, so the process proceeds to step S15. In step S15, the gear ratio setting unit 54 checks whether the gear ratio state of gear 4 is "temporary determination" or "confirmation". As shown in Table 4, the gear ratio state of gear 4 is "undetermined", so the process proceeds to step S21. In step S21, the i setting unit 55 increments i and returns to step S13.

[0039] For i = 5 - 9, it is the same as the case of i = 4 described above. So in step S21, the i setting unit 55 increments i and skips until i = 10.

[0040] In step S13, the i comparison unit 52 compares i with Ngear. Since i = 10, the process proceeds to step S22. In step S22, the i setting unit 55 resets i to 1 and then proceeds to step S23 and proceeds. In step S23, the gear ratio setting unit 54 checks whether there is one or more gear ratio states of "temporary determination" or "confirmation" among the gear ratio states of all gears. As shown in Table 4, since the gear ratio states of all gears are "undetermined", the process proceeds to step S24. In step S24, the gear ratio setting unit 54 sets the gear ratio states of all gears to "undetermined". In the first embodiment, since the gear ratio states of all gears are already "undetermined", nothing is done and the process returns to step S11.

[0041] In step S11, the rotation speed calculation unit 51 receives a signal indicating the rotation speed of the wheel (rear wheel 3) from the first sensor 5 and detects the vehicle speed change timing (whether the 2 / 12 vehicle speed pulse has arrived). At the vehicle speed change timing (when the 2 / 12 vehicle speed pulse arrives), in step S12, the rotation speed calculation unit 51 calculates the rotation speed ratio R based on the signal from the first sensor 5 and the signal indicating the rotation speed of the motor from the second sensor 6. In the first embodiment, since the rotation speed ratio R = 0.63 remains unchanged, when i = 1, steps S12 to S21 are the same as in the case of the 1 / 12 vehicle speed pulse described above. Therefore, in step S21, the i setting unit 55 counts up i and skips until i = 2.

[0042] In step S13, the i comparison unit 52 compares i with Ngear. Since i = 2, the process proceeds to step S14. In step S14, the threshold comparison unit 53 checks whether the rotation speed ratio R = 0.63 is within the threshold range. From Table 1, the threshold for i = 2 is 0.614 to 0.750, and since the rotation speed ratio R = 0.63 is within the threshold range, the process proceeds to step S16. In step S16, the C setting unit 56 counts up the count value C of gear 2. Specifically, the count value C of gear 2 in Table 5 is changed from 1 to 2.

Table 5

[0043] In step S13, the i comparison unit 52 compares i with Ngear. Since i = 3 the process proceeds to step S14. In step S14, the threshold comparison unit 53 checks whether the rotation speed ratio R = 0.63 is within the threshold range. From Table 1, the threshold for i = 3 is 0.532 - 0.650, and since the rotation speed ratio R = 0.63 is within the threshold range, the process proceeds to step S16. In step S16, the C setting unit 56 increments the count value C of gear 3. Specifically, the count value C of gear 3 in Table 6 is changed from 1 to 2.

Table 6

[0044] Similarly, at subsequent vehicle speed change timings (when 3 / 12, 4 / 12, 5 / 12 vehicle speed pulses arrive), as shown in Table 7, the C setting unit increments the count values C of gears 2 and 3.

Table 7

[0045] The flow of each vehicle speed change timing (3 / 12, 4 / 12, 5 / 12 vehicle speed pulses) is the same as the above-described case. Also, in the flow of the vehicle speed change timing (6 / 12 vehicle speed pulse), when i = 1, steps S12 to S21 are the same as each vehicle speed change timing (1 / 12, 2 / 12, 3 / 12, 4 / 12, 5 / 12 vehicle speed pulses), so in step S21, the i setting unit 55 counts up i and skips until i = 2.

[0046] In step S13, the i comparison unit 52 compares i with Ngear. Since i = 2, it proceeds to step S14. In step S14, the threshold comparison unit 53 checks whether the rotation speed ratio R = 0.63 is within the threshold range. From Table 1, the threshold for i = 2 is 0.614 to 0.750, and since the rotation speed ratio R = 0.63 is within the threshold range, it proceeds to step S16. In step S16, the C setting unit 56 counts up the count value C of gear 2. Specifically, the count value C of gear 2 in Table 8 is changed from 5 to 6.

Table 8

Table 9

[0047] Similarly, in the loop of the vehicle speed change timing (6 / 12 vehicle speed pulses), since the count value C of gear 3 also becomes 6, as shown in Table 10, the gear ratio setting unit 54 changes the gear ratio state of gear 3 to "temporary determination" as well.

Table 10

[0048] For i = 4 to 9, since it is the same as the cases of the above-described respective vehicle speed change timings (1 / 12, 2 / 12, 3 / 12, 4 / 12, 5 / 12 vehicle speed pulses), in step S21, the i setting unit 55 counts up i and skips until i = 10.

[0049] In step S13, the i comparison unit 52 compares i with Ngear. Since i = 10, it proceeds to step S22. In step S22, the i setting unit 55 resets i to 1 and then proceeds to step S23. In step S23, the gear ratio setting unit 54 checks whether there is one or more gear ratio states of "temporary determination" or "confirmed" among the gear ratio states of all gears. As shown in Table 10, since the gear ratio states of gears 2 and 3 are "temporary determination", it proceeds to step S25. In step S25, the gear ratio setting unit 54 checks whether the number of gear ratio states of "temporary determination" is one and whether the upper and lower gear ratio states are "excluded". As shown in Table 10, since the number of gears with the gear ratio state of "temporary determination" is two, namely gears 2 and 3, it returns to step S11.

[0050] Similarly, at subsequent vehicle speed change timings (when the 7 / 12, 8 / 12, and 9 / 12 vehicle speed pulses arrive), as shown in Table 11, the C setting unit increments the count values C of gears 2 and 3. In Example 1, since the rotation speed ratio R = 0.63 remains unchanged, there is no change in the gear ratio state, and the loop continues. Therefore, the gear ratio state is not determined, and both gears 2 and 3 are in a provisional determination state. As a result, by provisionally determining both adjacent gear ratios (gears 2 and 3) as candidates, the risk of misjudgment can be reduced. However, when the count value C reaches the count threshold, it is not necessary to perform further counting up. That is, in Table 11, the count values C of gears 2 and 3 may be stopped at 6.

Table 11

[0051] In Example 1, as shown in Table 1 by the control device 50, among the numerical ranges corresponding to a plurality of gear ratios (gears 1 to 9), one or more numerical ranges including the gear ratio calculated by Equation (1) are determined (step S14), and one or more gear ratios (gears 2, 3) corresponding to the one or more numerical ranges are candidates for the predetermined gear ratio.

[0052] In Example 2, when the rotation speed ratio changes from the state of Example 1 (R = 0.63) to R = 0.55 and the first vehicle speed pulse after the change arrives, gear 2 deviates from the threshold (NO in step S14). Since gear 2 was in a provisional determination state (YES in step S15), gear 2 is "excluded" (step S20). Since R = 0.55 is included in the thresholds of both gear 3 and gear 4 (step S14), the count values C of gear 3 and gear 4 increase (step S16) and exceed the count threshold (YES in step S17). As a result, gear 3 and gear 4 become "provisional determinations" (step S19). The following will be described in detail along the flowchart.

[0053] In step S11, the rotation speed calculation unit 51 receives a signal indicating the rotation speed of the wheel (rear wheel 3) from the first sensor 5, and detects the vehicle speed change timing (whether the 10 / 12 vehicle speed pulse has arrived). At the vehicle speed change timing (when the 10 / 12 vehicle speed pulse arrives), in step S12, the rotation speed calculation unit 51 calculates the rotation speed ratio R based on the signal from the first sensor 5 and the signal indicating the rotation speed of the motor from the second sensor 6. In the second embodiment, it is assumed that the rotation speed ratio R = 0.55.

[0054] In step S13, the i comparison unit 52 compares i with Ngear. Since i = 1, it proceeds to step S14. In step S14, the threshold comparison unit 53 checks whether the rotation speed ratio R = 0.55 is within the threshold range. From Table 1, the threshold for i = 1 is 0.736 to 0.900, and since the rotation speed ratio R = 0.55 is not within the threshold range, it proceeds to step S15. In step S15, the gear ratio setting unit 54 checks whether the gear ratio state of gear 1 is "temporary determination" or "confirmed". As shown in Table 11, the gear ratio state of gear 1 is "undetermined", so it proceeds to step S21. In step S21, the i setting unit 55 increments i and returns to step S13.

[0055] In step S13, the i comparison unit 52 compares i with Ngear. Since i = 2, it proceeds to step S14. In step S14, the threshold comparison unit 53 checks whether the rotation speed ratio R = 0.55 is within the threshold range. From Table 1, the threshold for i = 2 is 0.614 to 0.750, and since the rotation speed ratio R = 0.55 is not within the threshold range, it proceeds to step S15. In step S15, the gear ratio setting unit 54 checks whether the gear ratio state of gear 2 is "temporary determination" or "confirmed". As shown in Table 11, the gear ratio state of gear 2 is "temporary determination", so it proceeds to step S20. In step S20, as shown in Table 12, the gear ratio setting unit 54 changes the gear ratio state of gear 2 from "temporary determination" to "exclusion", and the C setting unit 56 resets (to zero) the count value C.

Table 12

[0056] In step S13, the i comparison unit 52 compares i with Ngear. Since i = 3, it proceeds to step S14. In step S14, the threshold comparison unit 53 checks whether the rotation speed ratio R = 0.55 is within the threshold range. From Table 1, the threshold for i = 3 is 0.532 - 0.650, and since the rotation speed ratio R = 0.55 is within the threshold range, it proceeds to step S16. In step S16, the C setting unit 56 counts up the count value C of gear 3. Specifically, it changes the count value C of gear 3 in Table 13 from 9 to 10.

Table 13

[0057] In step S13, the i comparison unit 52 compares i with Ngear. Since i = 4 it proceeds to step S14. In step S14, the threshold comparison unit 53 checks whether the rotation speed ratio R = 0.55 is within the threshold range. From Table 1, the threshold for i = 4 is 0.470 to 0.575, and since the rotation speed ratio R = 0.55 is within the threshold range, the process proceeds to step S16. In step S16, the C setting unit 56 increments the count value C of gear 4. Specifically, the count value C of gear 4 in Table 14 is changed from 0 to 1.

Table 14

[0058] For i = 5 to 9, it is the same as the case of i = 1 described above. So in step S21, the i setting unit 55 increments i and skips until i = 10.

[0059] In step S13, the i comparison unit 52 compares i with Ngear. Since i = 10, the process proceeds to step S22. In step S22, the i setting unit 55 resets i to 1 and then proceeds to step S23. In step S23, the gear ratio setting unit 54 checks whether there is one or more gear ratio states of "temporary determination" or "confirmed" among the gear ratio states of all gears. As shown in Table 14, the gear ratio state of gear 3 is "temporary determination", so the process proceeds to step S25. In step S25, the gear ratio setting unit 54 checks whether there is one gear ratio state of "temporary determination" and whether the upper and lower gear ratio states are "excluded". As shown in Table 14, the gear with the gear ratio state of "temporary determination" is only gear 3, the gear ratio state of gear 2 above gear 3 is "excluded", and the gear ratio state of gear 4 below gear 3 is "undetermined". Therefore, the process returns to step S11.

[0060] Similarly, at subsequent vehicle speed change timings (when the 11 / 12, 12 / 12, 1 / 12, and 2 / 12 vehicle speed pulses arrive), as shown in Table 15, the C setting unit 56 increments the count values C of gears 3 and 4.

Table 15

[0061] Since the flow of each vehicle speed change timing (11 / 12, 12 / 12, 1 / 12, 2 / 12 vehicle speed pulses) is the same as the above-described case, in step S16 of the loop at the vehicle speed change timing (3 / 12 vehicle speed pulse), as shown in Table 16, the process skips until the count value C of gear 4 reaches 6.

Table 16

[0062] In step S17, the count threshold comparison unit 57 compares the count value C of gear 4 with the count threshold (6 in this embodiment). Since 6 ≤ C, the process proceeds to step S18. In step S18, the gear ratio setting unit 54 checks whether the gear ratio state of gear 4 is "excluded". As shown in Table 16, the gear ratio state of gear 4 is "undetermined", so the process proceeds to step S19. In step S19, as shown in Table 17, the gear ratio setting unit 54 changes the gear ratio state of gear 4 from "undetermined" to "temporary determination".

Table 17

[0063] For i = 5 to 9, since it is the same as the case of i = 4 in the first embodiment, in step S21, the i setting unit 55 increments i and skips until i = 10.

[0064] In step S13, the i comparison unit 52 compares i with Ngear. Since i = 10, it proceeds to step S22. In step S22, the i setting unit 55 resets i to 1 and then proceeds to step S23. In step S23, the gear ratio setting unit 54 checks whether there is one or more "temporary determination" or "confirmed" gear ratio states among all the gear ratio states of the gears. As shown in Table 17, since the gear ratio states of gears 3 and 4 are "temporary determination", it proceeds to step S25. In step S25, the gear ratio setting unit 54 checks whether the number of "temporary determination" gear ratio states is one and whether the upper and lower gear ratio states are "excluded". As shown in Table 17, since there are two gears, gears 3 and 4, in the "temporary determination" gear ratio state, it returns to step S11. In the second embodiment, the gear ratio state is not confirmed, and both gears 3 and 4 are in the temporary determination state. As a result, by tentatively determining both adjacent gear ratios (gears 3 and 4) as candidates, the risk of misjudgment can be reduced.

[0065] In the third embodiment, the ratio of the rotational speeds changes from the state of the second embodiment (R = 0.55) to R = 0.63. When the first vehicle speed pulse comes after the change, gear 4 deviates from the threshold value (NO in step S14). Since gear 4 was in the temporary determination state (YES in step S15), gear 4 is "excluded" (step S20). At this time, gear 3 has not been "excluded" yet, and the gear ratio that is in the temporary determination or confirmed state is only gear 3 (YES in step S23). Since the upper and lower gears 2 and 4 of gear 3 are "excluded", gear 3 becomes "confirmed" (YES in step S25). The following will be described in detail along the flowchart.

[0066] In step S11, the rotation speed calculation unit 51 receives a signal indicating the rotation speed of the wheel (rear wheel 3) from the first sensor 5 and detects the vehicle speed change timing (whether the 4 / 12 vehicle speed pulse has arrived). At the vehicle speed change timing (when the 4 / 12 vehicle speed pulse arrives), in step S12, the rotation speed calculation unit 51 calculates the rotation speed ratio R based on the signal from the first sensor 5 and the signal indicating the rotation speed of the motor from the second sensor 6. In Embodiment 3, the rotation speed ratio R = 0 .63 is assumed.

[0067] In step S13, the i comparison unit 52 compares i with Ngear. Since i = 1, it proceeds to step S14. In step S14, the threshold comparison unit 53 checks whether the rotation speed ratio R = 0.63 is within the threshold range. From Table 1, the threshold for i = 1 is 0.736 to 0.900, and since the rotation speed ratio R = 0.63 is not within the threshold range, it proceeds to step S15. In step S15, the gear ratio setting unit 54 checks whether the gear ratio state of gear 1 is "temporary determination" or "confirmed". As shown in Table 17, the gear ratio state of gear 1 is "undetermined", so it proceeds to step S21. In step S21, the i setting unit 55 increments i and returns to step S13.

[0068] In step S13, the i comparison unit 52 compares i with Ngear. Since i = 2, it proceeds to step S14. In step S14, the threshold comparison unit 53 checks whether the rotation speed ratio R = 0.63 is within the threshold range. From Table 1, the threshold for i = 2 is 0.614 to 0.750, and since the rotation speed ratio R = 0.63 is within the threshold range, it proceeds to step S16. In step S16, the C setting unit 56 increments the count value C of gear 2. Specifically, it changes the count value C of gear 2 in Table 18 from 0 to 1.

Table 18

[0069] In step S13, the i comparison unit 52 compares i with Ngear. Since i = 3, the process proceeds to step S14. In step S14, the threshold comparison unit 53 checks whether the rotation speed ratio R = 0.63 is within the threshold range. From Table 1, the threshold for i = 3 is 0.532 - 0.650, and the rotation speed ratio R = 0.63 is within the threshold range, so the process proceeds to step S16. In step S16, the C setting unit 56 increments the count value C of gear 3. Specifically, the count value C of gear 3 in Table 19 is changed from 15 to 16.

Table 19

[0070] In step S13, the i comparison unit 52 compares i with Ngear. Since i = 4, it proceeds to step S14. In step S14, the threshold comparison unit 53 checks whether the rotation speed ratio R = 0.63 is within the threshold range. From Table 1, the threshold for i = 4 is 0.470 to 0.575, and since the rotation speed ratio R = 0.63 is not within the threshold range, it proceeds to step S15. In step S15, the gear ratio setting unit 54 checks whether the gear ratio state of gear 4 is "temporary determination" or "confirmed". As shown in Table 19, the gear ratio state of gear 4 is "temporary determination", so it proceeds to step S20. In step S20, as shown in Table 20, the gear ratio setting unit 54 changes the gear ratio state of gear 4 from "temporary determination" to "excluded", and the C setting unit 56 resets (to zero) the count value C.

Table 20

[0071] For i = 5 to 9, it is the same as the case of i = 1 described above. So, in step S21, the i setting unit 55 increments i and skips until i = 10.

[0072] In step S13, the i comparison unit 52 compares i with Ngear. Since i = 10, it proceeds to step S22. In step S22, the i setting unit 55 resets i to 1 and then proceeds to step S23. In step S23, the gear ratio setting unit 54 checks whether there is one or more "temporary determination" or "confirmed" gear ratio states among all the gear ratio states of the gears. As shown in Table 20, the gear ratio state of gear 3 is "temporary determination", so it proceeds to step S25. In step S25, the gear ratio setting unit 54 checks whether there is one gear ratio state of "temporary determination" and whether the upper and lower gear ratio states are "excluded". As shown in Table 20, the gear with the gear ratio state of "temporary determination" is only gear 3, and the gear ratio state of gear 2 above gear 3 is "excluded", and the gear ratio state of gear 4 below gear 3 is also "excluded". Therefore, the process proceeds to step S26. In step S26, as shown in Table 21, the gear ratio setting unit 54 changes the gear ratio state of gear 3 from "temporary determination" to "confirmed".

Table 21

[0073] The control device 50 determines that the gear ratio is the current one when the rotation speed ratio R is within the threshold range in a predetermined period (the time during which the wheel (rear wheel 3) makes one rotation), as shown in Table 1. However, even after the determination, the gear ratio state determination process continues. When the driver changes the gear ratio, the gear ratio determined before the change no longer satisfies Equation (1). At this time, the control device 50 detects that the gear ratio has been changed and limits the output of the motor. After the output of the motor is limited, if it is determined that the gear ratio is the predetermined one according to the gear ratio state determination process, the limitation of the output of the motor is released.

[0074] Summarizing Embodiments 1 to 3, the control device 50 is configured as follows. Based on the signal indicating the rotational speed of the wheel from the first sensor and the signal indicating the rotational speed of the motor from the second sensor, calculate the rotational speed ratio R according to Equation (1) (steps S11 and S12). Regarding one or more gear ratios among all the gear ratios (gears 1 to 9), the rotational speed ratio When R is within the threshold range for a predetermined number of times (count threshold, 6 in this embodiment) or more (step S17), temporarily determine one or more gear ratios (step S19). When the ratio R of the rotational speeds is no longer within the threshold range for the temporarily determined gear ratio (step S15), the gear ratio is excluded (step S20). When both of the two gear ratios adjacent to one temporarily determined gear ratio are excluded (step S25), the one temporarily determined gear ratio is determined as a gear ratio (step S26).

[0075] FIG. 8(a) is a simulation diagram for explaining detection and motor control during gear shifting in an electric assist bicycle. The vertical axis represents the status of gear determination in the software by voltage output, and the horizontal axis represents time. "Unconnected" represents the case where the assist output is suppressed at the start of pedaling or when a gear change is detected and the assist output is suppressed. As shown in FIG. 8(a), the time ta from when the gear is changed from gear 9 to gear 8 until it is confirmed as gear 8 through the above-described gear ratio state determination process is longer than the time tb from when the gear is changed from gear 8 to gear 7 until it is confirmed as gear 7. The same magnitude relationship holds, and the time tc from when the gear is changed from gear 2 to gear 1 until it is confirmed as gear 1 is the shortest. This is because for heavier gears, the difference in the number of teeth between the upper and lower gears is smaller, so the time it takes for the gear to be confirmed is longer compared to lighter gears. For example, as shown in Table 1, the number of teeth of gear 9 is 11 and the number of teeth of gear 8 is 13, so the difference in the number of teeth between gears 9 and 8 is 2, while the number of teeth of gear 2 is 30 and the number of teeth of gear 1 is 36, so the difference in the number of teeth between gears 2 and 1 is 6. Note that the time from when the gear is changed from gear 9 to gear 8 until it is confirmed as gear 8 is the same as the time from when the gear is changed from gear 8 to gear 9 until it is confirmed as gear 9.

[0076] FIG. 8(b) is an enlarged simulation diagram of the portion from when the gear is changed from gear 9 to gear 8 until it is confirmed as gear 8 through the gear ratio state determination process shown in FIG. 7 in FIG. 8(a). Immediately after the gear is changed from gear 9 to gear 8, the assist output is suppressed. Next, gear 8 is temporarily determined, and the voltage output becomes the voltage level of gear 8. Next, once gears 8 and 7 are tentatively determined, the voltage output becomes the voltage level between gears 8 and 7. Next, gear 7 is excluded, and only gear 8 is tentatively determined, so the voltage output becomes the voltage level of gear 8. Next, gear 9 is also tentatively determined. Since gears 8 and 9 are tentatively determined, the voltage output becomes the voltage level between gears 8 and 9. Finally, gear 9 is excluded, gear 8 is confirmed, and the voltage output becomes the voltage level of gear 8.

[0077] Figure 8(c) is an enlarged simulation diagram of the portion in Figure 8(a) from gear 2 to gear 1 until it is confirmed as gear 1 through the gear ratio state determination process shown in Figure 7. Immediately after the change from gear 2 to gear 1, the assist output is suppressed. Next, gear 1 is tentatively determined, and the voltage output becomes the voltage level of gear 1. As described above, since the difference in the number of teeth between gears 2 and 1 is large, there is no ambiguous determination.

Explanation of Signs

[0078] 1... Electric assist bicycle, 2... First wheel (front wheel), 3... Second wheel (rear wheel), 4... Pedal, 5... First sensor, 6... Second sensor, 8... Crank (front), 9... (Rear) gear sprocket, 50... Control device, 50a... Control circuit, 50b... Drive circuit, 51... Rotation speed calculation unit, 52... i comparison unit, 53... Threshold comparison unit, 54... Gear ratio setting unit, 55... i setting unit, 56... C setting unit, 57... Count threshold comparison unit, 58... Drive control signal generation unit, 100... Rotation device (MDU: Motor drive unit)

Claims

1. The time from when the first gear ratio is changed to the second gear ratio until the pedal assist corresponding to the second gear ratio starts is different from the time from when the third gear ratio is changed to the fourth gear ratio until the pedal assist corresponding to the fourth gear ratio starts, an electric assist bicycle.

2. Equipped with a control device, The time from when the stopped control device starts until the pedal assist corresponding to the gear ratio starts is longer than the time from when the gear ratio is changed until the pedal assist corresponding to the changed gear ratio starts, An electric assist bicycle.

3. A wheel, A control device, A reduction gear, and a rotating device having a motor for assisting the pedal, A sensor for detecting the rotational speed of the wheel, A sensor for detecting the rotational speed of the motor, Comprising, N ｗ be the rotational speed [rpm] of the wheel, N ｍ be the rotational speed [rpm] of the motor, gr ＭＤＵ Define Equation (1) with the reduction ratio of the rotating device as follows N ｍ / (gr ＭＤＵ ·N ｗ ) Formula (1) The control device determines whether the magnitude of formula (1) is included within a predetermined range corresponding to the gear ratio, The electric assist bicycle according to claim 1.

4. A wheel, A reduction gear, and a rotating device having a motor for assisting the pedal, A sensor for detecting the rotational speed of the wheel, A sensor for detecting the rotational speed of the motor, Comprising, N ｗ be the rotational speed [rpm] of the wheel, N ｍ be the rotational speed [rpm] of the motor, gr ＭＤＵ Define Equation (1) with the reduction ratio of the rotating device as follows N ｍ / (gr ＭＤＵ ·N ｗ ) Formula (1) The control device determines whether the magnitude of formula (1) is included within a predetermined range corresponding to the gear ratio, The electric assist bicycle according to claim 2.

5. The time until the pedal assist corresponding to the gear ratio starts is within the time taken for one rotation of the wheel, The electric assist bicycle according to any one of claims 1 to 4.

6. The control device, Based on the signal indicating the rotational speed of the wheel from the first sensor and the signal indicating the rotational speed of the motor from the second sensor, calculates the ratio of the rotational speeds according to formula (1), For one or more of all the gear ratios, if the ratio of the rotational speeds is within the threshold range for a predetermined number of times, tentatively determines the one or more gear ratios, For a gear ratio that has been tentatively determined, if the ratio of the rotational speeds is no longer within the threshold range, excludes the gear ratio, If both of the two gear ratios adjacent to the tentatively determined one gear ratio are excluded, the tentatively determined One gear ratio is determined as the gear ratio. The electric assist bicycle according to claim 3 or 4.

7. A first step of determining a candidate for the predetermined gear ratio before the elapse of a first period after being changed to the predetermined gear ratio, A second step of determining the predetermined gear ratio from candidates for the predetermined gear ratio after the elapse of the first period and before the elapse of the second period; A method for determining a gear ratio of an electric assist bicycle, comprising: **Claim 8** The electric assist bicycle includes: a wheel; a control device; a reduction gear, and a rotating device having a motor for assisting the pedal; a sensor for detecting the rotational speed of the wheel; a sensor for detecting the rotational speed of the motor; and is provided with: N ｗ be the rotational speed [rpm] of the wheel, N ｍ be the rotational speed [rpm] of the motor, gr ＭＤＵ Define Equation (1) with the reduction ratio of the rotating device as follows N ｍ / (gr ＭＤＵ ·N ｗ ) Formula (1) In the first step, the control device determines one or more numerical ranges including the gear ratio calculated by formula (1) among numerical ranges corresponding to a plurality of gear ratios, and one or more gear ratios corresponding to the one or more numerical ranges are candidates for the predetermined gear ratio. The method for determining a gear ratio of an electric assist bicycle according to claim 7. **Claim 9** A period including the first period and the second period is within the time taken for one rotation of the wheel. The method for determining a gear ratio of an electric assist bicycle according to claim 7 or 8.

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