Control device, electric-assist bicycle, and assist control method

Abstract

To provide a control device capable of preventing unnecessary assist actions, for example.SOLUTION: For example, provided is a control device (1) that assists with rotating pedals (4) if a ratio (R) of the rotational speed (Vb) of wheels (2, 3) and the rotational speed (Vp) of the pedals (4) is within a prescribed range, and stops assisting with rotating the pedals (4) if the ratio (R) is outside of the prescribed range.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a control device, an electrically assisted bicycle, and an assist control method. [Background technology]

[0002] In devices such as electrically assisted bicycles that have pedals and wheels, there are known control devices that control whether or not to assist the rotation of the pedals. For example, Patent Document 1 discloses a drive unit that stops assist control based on the amplitude of the torque while the crankshaft rotates through a specified range of rotation angles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-139067 A Summary of the Invention [Problem to be solved by the invention]

[0004] In devices such as electrically assisted bicycles, it is sometimes desirable to prevent the assist function from operating when traveling downhill, coasting, etc. An example of the objective of the present invention is to provide a control device that can prevent unnecessary assist operation. [Means for solving the problem]

[0005] A control device, which is an example of the present invention, assists the rotation of the pedal when the ratio between the rotation speed of the wheel and the rotation speed of the pedal is within a predetermined range, and cancels the assistance of the rotation of the pedal when the ratio is outside the predetermined range.

[0006] Another example of an assist control method of the present invention includes a step of acquiring a wheel rotation speed, a step of acquiring a pedal rotation speed, and a step of determining whether or not to assist the pedal rotation based on the ratio between the wheel rotation speed and the pedal rotation speed. [Brief description of the drawings]

[0007] [Figure 1] 1 is a side view of an electrically assisted bicycle equipped with a control device according to an embodiment that is an example of the present invention. [Diagram 2] 1 is a block diagram showing a schematic configuration of a control device, a sensor, and a motor according to an embodiment that is an example of the present invention. [Diagram 3] 4 is a flowchart showing an example of a flow of control by a control device according to an embodiment which is an example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the drawings. Fig. 1 is a side view of an electrically assisted bicycle 100 equipped with a control device (motor control drive device) 1 according to this embodiment.

[0009] As shown in Fig. 1, an electrically assisted bicycle 100 includes a frame F, handlebars H, a saddle S, a transmission body C, a battery B, a drive unit D, a first wheel (front wheel) 2, a second wheel (rear wheel) 3, and pedals 4. When a rider sits on the saddle S of the electrically assisted bicycle 100 and rotates the pedals 4 with their feet, driving force is transmitted to a wheel (typically the rear wheel 3) via the transmission body C, with assistance from the drive unit D as necessary, enabling the bicycle to travel forward. The transmission body C may be a chain or a belt.

[0010] A first sensor 5 for detecting the rotation speed Vb of the wheel is disposed, for example, near the rotation axis of the front wheel 2 or the rear wheel 3. In this specification, "detecting the rotation speed Vb of the wheel" may mean that the first sensor 5 itself calculates the rotation speed Vb of the wheel, that the first sensor 5 outputs a signal (output signal Sb) required for calculating the rotation speed Vb of the wheel to the control device 1, and the control device 1 calculates the rotation speed Vb of the wheel, or that the first sensor 5 outputs a signal (output signal Sb) required for calculating the rotation speed Vb of the wheel to another arithmetic device (not shown), and the arithmetic device to which the output signal Sb is input calculates the rotation speed Vb of the wheel and outputs it to the control device 1. FIG. 1 shows an example in which the first sensor 5 is disposed on the front wheel 2. As the first sensor 5, a known sensor capable of detecting the rotation speed Vb of the wheel or outputting a signal required for calculating the rotation speed Vb of the wheel can be used. The first sensor 5 may be, for example, a magnetic sensor or a Hall sensor capable of detecting the number of rotations or the rotation angle of the wheel, or may be an optical sensor capable of detecting the number of rotations or the rotation angle of the wheel. The first sensor 5 may be disposed at a position where the number of rotations or the rotation angle of the wheel can be detected, for example, at a position away from the rotation axis of the front wheel 2 or the rear wheel 3.

[0011] The drive unit D and the battery B are typically arranged around a crankshaft (not shown) connected to the pedal 4. The drive unit D includes a control device 1, a motor M, a reducer (not shown), a second sensor 6 that detects the rotation speed Vp of the pedal 4, and a third sensor 7 as a torque sensor that detects the pedal force applied to the pedal 4. In FIG. 1, the control device 1, the motor M, the second sensor 6, and the third sensor 7 are indicated by hidden lines (dashed lines). Note that the control device 1 may be arranged in part or in whole outside the drive unit D. The battery B supplies power to the motor M and the control device 1, and the motor M and the control device 1 operate.

[0012] The motor M is controlled by the control device 1 and assists the rotation of the pedal 4 via a reducer. In this specification, "rotation of the pedal 4" refers to the rotation of the pedal 4 around the crankshaft. In this specification, "assisting the rotation of the pedal 4" includes reducing the force (pedaling force) required to rotate the pedal 4 and 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). The motor M may be equipped with a sensor such as a Hall IC for detecting the rotation angle of the rotor.

[0013] The second sensor 6 is a sensor that detects the rotation speed Vp of the pedal 4. In this specification, "detecting the rotation speed Vp of the pedal 4" may mean that the second sensor 6 itself calculates the rotation speed Vp of the pedal 4, that the second sensor 6 outputs a signal (output signal Sp) required to calculate the rotation speed Vp of the pedal 4 to the control device 1, and the control device 1 calculates the rotation speed Vp of the pedal 4, or that the second sensor 6 outputs a signal (output signal Sp) required to calculate the rotation speed Vp of the pedal 4 to another calculation device (not shown), and the calculation device to which the output signal Sp is input calculates the rotation speed Vp of the pedal 4 and outputs it to the control device 1. The second sensor 6 may be, for example, a sensor that is generally called a cadence sensor. The second sensor 6 may be a known sensor that can output a signal, and examples of the sensor include a magnetic sensor, an optical sensor, and a mechanical sensor. FIG. 1 shows an example in which the second sensor 6 is housed in the housing of the drive unit D, but the second sensor 6 may be disposed outside the housing of the drive unit D. The second sensor 6 may be disposed on the pedal 4, the crank arm connecting the pedal 4 to the crankshaft, the crankshaft, or the frame F, or may be disposed at any location on any other component that constitutes the bicycle.

[0014] The third sensor 7 is a torque sensor that detects the pedaling force applied to the pedal 4. In this specification, "detecting the pedaling force applied to the pedal 4" may mean that the third sensor 7 itself calculates the pedaling force, that the third sensor 7 outputs a signal St required for calculating the pedaling force to the control device 1, and the control device 1 calculates the pedaling force, or that the third sensor 7 outputs a signal St required for calculating the pedaling force to another arithmetic device (not shown), and the arithmetic device to which the signal St is input calculates the pedaling force and outputs it to the control device 1. The third sensor 7 may be a known sensor capable of outputting a signal, such as a magnetostrictive sensor or a mechanical sensor. The third sensor 7 may be disposed on the pedal 4, on a crank arm connecting the pedal 4 and the crankshaft, on the crankshaft, on the housing of the drive unit D, or on any other location. The power-assisted bicycle 100 can adjust the output of the motor M, etc., according to the pedaling force detected by the third sensor 7.

[0015] The control device 1 will be described in detail below. The control device 1 is configured to assist the rotation of the pedal 4 when the ratio R between the rotation speed Vb of the wheel (the front wheel 2 in the example shown in FIG. 1) on the side where the first sensor 5 is located and the rotation speed Vp of the pedal 4 is within a predetermined range, and to cancel the assist of the rotation of the pedal 4 (do not assist the rotation of the pedal 4) when the ratio R is outside the predetermined range. The control device 1 determines whether the ratio R is within the predetermined range based on the output signal Sb of the first sensor 5 and the output signal Sp of the second sensor 6.

[0016] 2 is a block diagram showing a schematic configuration of the control device 1, the sensors (first sensor 5, second sensor 6, and third sensor 7), and the motor M according to this embodiment. The control device 1 has, for example, a control circuit 10a and a drive circuit 10b. The components of the control device 1 shown in FIG. 2 are only a part of the whole, and the control device 1 may have other components in addition to those shown in FIG. 2.

[0017] The control circuit 10a 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 a RAM and a 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 a dedicated line.

[0018] The control circuit 10a has, for example, a first calculation unit (first operation unit) 11, a second calculation unit (second operation unit) 12, a judgment unit 13, a drive amount determination unit 14, and a drive control signal generation unit 15 as functional blocks. The first calculation unit 11, the second calculation unit 12, the judgment unit 13, the drive amount determination unit 14, and the drive control signal generation unit 15 are realized, for example, by a processor in a program processing device serving as the control circuit 10a, which executes various calculation processes according to programs stored in a memory, and controls peripheral circuits such as a counter and an A / D conversion circuit. Note that the control circuit 10a may have other functions.

[0019] The control circuit 10a receives signals output from the first sensor 5, the second sensor 6, and the third sensor 7. The first calculation unit 11 calculates the rotation speed Vb of the wheel based on the output signal Sb input from the first sensor 5. The second calculation unit 12 calculates the rotation speed Vp of the pedal 4 based on the output signal Sp input from the second sensor 6.

[0020] The determination unit 13 determines whether or not the ratio R of Vb to Vp is within a predetermined range, based on the rotation speed Vb of the wheel calculated by the first calculation unit 11 and the rotation speed Vp of the pedal 4 calculated by the second calculation unit 12. Note that the determination unit 13 is not limited to calculating the ratio R in the form of a strict "ratio," i.e., "A:B" or the like, or storing it in a storage device, and may indirectly determine whether or not the ratio R is within a predetermined range, for example, by the method described below.

[0021] Whether the ratio R is within a predetermined range may be determined, for example, by comparing the value of Vb with a value Vbv obtained by multiplying Vp by a predetermined value X. Here, the value X may be, for example, the value of Vb / Vp when the pedal 4 is neither spinning nor stationary (when the rotation of the pedal 4 contributes to the rotation of the wheel). The value of Vb / Vp when the pedal 4 is neither spinning nor stationary can be calculated, for example, by a method described later. The value Vbv may be considered as a virtual rotation speed of the wheel based on the rotation speed Vp of the pedal 4 at a certain point in time.

[0022] The determination unit 13 may compare the value of Vb with a value Vbv obtained by multiplying Vp by a predetermined value X and determine that the ratio R is within a predetermined range when the value Vbv is, for example, within a range of -20% to +20% of Vb, within a range of -15% to +15% of Vb, within a range of -5% to +5% of Vb, within a range of -2% to +2% of Vb, or within a range of -1% to +1% of Vb.

[0023] Furthermore, the determination unit 13 may determine whether the ratio R is within a predetermined range by determining whether the ratio R is substantially equal to a predetermined value. Whether the ratio R is substantially equal to a predetermined value may be determined, for example, by determining whether the value of Vb is substantially equal to a value Vbv obtained by multiplying Vp by a value X. In this case, "substantially equal" may mean, for example, that the value Vbv is greater than -1% and less than +1% of Vb. Alternatively, the value Vbv may match Vb.

[0024] The determination unit 13 may determine whether the ratio R is within the predetermined range by another method. For example, the determination unit 13 may determine whether the ratio R is within the predetermined range by a method of comparing a value Xv obtained by dividing Vb by Vp (i.e., Xv=Vb / Vp) with a predetermined value X. In this case, the determination unit 13 may determine that the ratio R is within the predetermined range when the value Xv is within a range of −20% to +20% of the value X, within a range of −15% to +15% of the value X, within a range of −5% to +5% of the value X, within a range of −2% to +2% of the value X, or within a range of −1% to +1% of the value X. Furthermore, the determination unit 13 may determine whether the ratio R is substantially equal to a predetermined value by, for example, whether the value Xv and the value X are substantially equal. In this case, for example, the value Xv may be greater than −1% and less than +1% of the value X. Furthermore, the value Xv may match the value X.

[0025] If the ratio R is within a predetermined range, the judgment unit 13, for example, sets the assist on / off bit (SW) in the data register to "1" (SW=1). This state is also referred to as the assist setting register on (1). Also, if the ratio R is outside the predetermined range, the judgment unit 13, for example, resets the assist on / off bit (SW) in the data register (SW=0). This state is also referred to as the assist setting register off (0).

[0026] The drive amount determination unit 14 calculates and determines the drive amount required for assist based on the signal St from the third sensor 7, which is a torque sensor. When the value of SW is 1 and the drive amount calculated based on the signal St is greater than 0 (when it is determined that assist is required based on the third sensor 7), the drive amount determination unit 14 outputs a drive command signal Sc indicating a target state of the operation of the motor M.

[0027] The drive control signal generating unit 15 generates a drive control signal Sd for driving the motor M based on the drive command signal Sc, and controls the driving of the motor M. The drive control signal generating unit 15 may monitor the rotation state of the motor M by obtaining information such as the rotation angle and rotation speed of the motor M based on a signal from a sensor such as a Hall IC provided in the motor M, and may generate a drive control signal Sd so that the motor M is in a predetermined operating state, and provide the drive control signal Sd to the drive circuit 10b. The drive control signal Sd is, for example, a PWM (Pulse Width Modulation) signal.

[0028] Based on the drive control signal Sd, the drive circuit 10b excites coils corresponding to the three phases (U phase, V phase, and W phase) of the motor M to drive the motor M. The drive circuit 10b may have, for example, an inverter circuit that drives each coil, a pre-drive circuit that drives the inverter circuit in response to the drive control signal Sd, and a current detection circuit that detects the current flowing through each coil.

[0029] The control device 1 may be configured such that part or all of the control circuit 10a and part or all of the drive circuit 10b are packaged as a single integrated circuit device (IC), or the control circuit 10a and the drive circuit 10b are each packaged as separate integrated circuit devices.

[0030] Next, a control flow of the assist of the rotation of the pedal 4 by the control device 1 according to the present embodiment will be described. Fig. 3 is a flowchart showing an example of the control flow by the control device 1. However, the control method by the control device 1 is not necessarily limited to the following description and the one shown in Fig. 3.

[0031] First, the control device 1 sets the assist on / off bit (SW) in the data register to "1" (assist setting register on (1)) (step S1). Next, the control device 1 determines whether or not assistance is required for the rotation of the pedal 4 (step S2). Specifically, if the value of SW is 1 and the drive amount calculated based on the signal St is greater than 0, the process proceeds to step S3, and if not, the process proceeds to step S5.

[0032] When it is determined that the rotation of the pedal 4 needs to be assisted, the control device 1 drives the motor M to assist the rotation of the pedal 4 (step S3). Immediately after the motor M starts to assist the rotation of the pedal 4, the control device 1 acquires the rotation speed Vb of the wheel and the rotation speed Vp of the pedal, and calculates the predetermined value X as X=Vb / Vp (step S4). Here, "immediately after the motor M starts to assist the rotation of the pedal 4" may mean, for example, within one rotation, within 3 / 4 rotations, within 2 / 4 rotations, or within 1 / 4 rotation of the pedal 4 (within a rotation angle of 360 degrees, within 270 degrees, within 180 degrees, or within 90 degrees) after the motor M starts to assist the rotation of the pedal 4, and may mean within 5 seconds, within 3 seconds, within 1 second, within 0.5 seconds, or within 0.1 seconds after the motor M starts to assist the rotation of the pedal 4. Immediately after the motor M starts assisting the rotation of the pedal 4, it is considered that the pedal 4 is neither spinning nor stationary (the rotation of the pedal 4 contributes to the rotation of the wheel). Therefore, the value X can be considered as the value of Vb / Vp when the pedal 4 is neither spinning nor stationary.

[0033] In step S5, it is determined whether or not the rotation of the pedal 4 needs to be assisted based on the ratio R between Vb and Vp. That is, it is determined whether or not the ratio R is within a predetermined range determined based on the value X, and if the ratio R is within the predetermined range, the assist on / off bit (SW) in the data register is set to "1" (assist setting register on (1)) (step S6), and if the ratio R is outside the predetermined range, the assist on / off bit (SW) in the data register is reset (assist setting register off (0)) (step S7). After that, the process returns to step S2, and thereafter, steps S2 to S6 (or step S7) are repeated.

[0034] Here, as described above, the value X is calculated as the value of Vb / Vp when the pedal 4 is neither spinning nor stationary. Therefore, when the ratio R is outside a predetermined range determined based on the value X, it can be determined that the rotation of the pedal 4 does not contribute to the rotation of the wheel, and that assistance of the rotation of the pedal 4 is not necessary. Therefore, according to the above control flow, assistance is performed when assistance of the rotation of the pedal 4 is necessary, and assistance is released when assistance of the rotation of the pedal 4 is not necessary. In this way, the control device 1 according to this embodiment can prevent unnecessary operation of assistance.

[0035] Although the control device and the assist control method of the present invention have been described above with reference to preferred embodiments, the control device and the assist control method of the present invention are not limited to the configurations of any of the above-described embodiments.

[0036] In the control device and the assist control method of the present invention, the predetermined range of the ratio between the rotation speed of the wheel and the rotation speed of the pedal may change depending on the situation. In the control device and the assist control method of the present invention, it may be determined whether or not the ratio between the rotation speed of the wheel and the rotation speed of the pedal is within the predetermined range based on a value set at the time of manufacture or the like instead of the value X. Also, in the control device and the assist control method of the present invention, it may be determined whether or not the ratio between the rotation speed of the wheel and the rotation speed of the pedal is within the predetermined range based on a value arbitrarily set by the user.

[0037] In addition, those skilled in the art can appropriately modify the control device and assist control method of the present invention in accordance with conventionally known knowledge, and can change the shapes, dimensions, and combinations of the various components. As long as the components of the present invention are still included even after such modifications, they are of course included in the scope of the present invention. [Explanation of symbols]

[0038] 1...control device, 2, 3...wheel, 4...pedal, 5...first sensor, 6...second sensor, 7...third sensor, 100...electrically assisted bicycle, R...ratio, M...motor.

Claims

1. When the ratio between the rotation speed of the wheel and the rotation speed of the pedal is within a predetermined range, the rotation of the pedal is assisted. A control device that disengages assistance from the rotation of the pedal when the ratio is outside a predetermined range.

2. The control system of claim 1 , wherein the ratio is substantially equal to a predetermined value when the ratio is within a predetermined range.

3. Wheels and Pedals and A first sensor for detecting a rotation speed of the wheel; A second sensor for detecting a rotation speed of the pedal; A motor that assists the rotation of the pedal; The control device according to claim 1 or 2, which controls the motor; An electrically assisted bicycle.

4. The electrically assisted bicycle according to claim 3 , wherein the control device determines whether or not the ratio is within a predetermined range based on the output signal of the first sensor and the output signal of the second sensor.

5. 5. The electrically assisted bicycle according to claim 3, wherein the control device determines the predetermined range based on a value obtained from the rotational speed of the wheel and the rotational speed of the pedal immediately after the motor starts assisting the rotation of the pedal.

6. acquiring a rotational speed of a wheel; acquiring a rotational speed of the pedal; determining whether or not to assist the rotation of the pedal based on a ratio between a rotation speed of the wheel and a rotation speed of the pedal; The assist control method includes:

Images