Patent Description:
As typical bicycle control devices for detecting the speed of an electric bicycle, the following two types are known in the art, which will be hereinafter referred to as a "first exemplary bicycle control device" and a "second exemplary bicycle control device," respectively.

The first exemplary bicycle control device is configured to detect the speed of an electric bicycle based on a result of detection by a speed detection device. The speed detection device detects the rotating condition of wheels of the electric bicycle.

The second exemplary bicycle control device is configured to estimate the speed of an electric bicycle (see, for example, Patent Literature <NUM>). When finding the result of detection by a vehicle speed sensor equal to or lower than a predetermined speed or finding the vehicle speed sensor operating improperly, the bicycle control device of Patent Literature <NUM> estimates the speed of the bicycle based on the rotational velocity of a motor, either the top gear or highest gear ratio of the transmission, and the circumferential length of the wheels.

The first exemplary bicycle control device detects the speed of the electric bicycle based on a result of detection by the speed detection device. Thus, the speed of the electric bicycle is updated every time the wheels make one rotation. Therefore, if the bicycle is traveling at low speeds, it is difficult for the bicycle control device of this type to detect the speed of the electric bicycle and control its power train with sufficient accuracy.

In the second exemplary bicycle control device, when the user changes the gear position, the rotational ratio changes. Thus, the second exemplary bicycle control device requires a sensor for determining the gear position of the transmission of the electric bicycle. Alternatively, since estimation needs to be made at the top gear (at the highest speed) of the transmission, it is difficult for the second exemplary bicycle control device to obtain sufficient auxiliary power when the gear position is lowered.

<CIT> describes methods and systems for controlling power-assisted pedal electric bicycles. Each system incorporates at least one control map that defines the dynamic response of a reference model representing desired bicycle velocity in response to the measured pedal torque imparted by the rider. The reference model contains parameters defining the desired properties of the bicycle, including desired mass and drag properties. In one embodiment, the system implements a "pedal centric" control method wherein measured rider-actuated pedal torque and the reference model are used to determine a desired pedal velocity. In another embodiment, the system implements a "wheel centric" control method wherein measured rider-actuated pedal torque and the reference model are used to determine the desired velocity of the wheel coupled to the drive motor. A closed loop velocity servo controls the motor to minimize the error between the desired rotational velocity and actual rotational velocity.

This document discloses the following features of claim <NUM>: A bicycle control device for use with a speed detection device and a rotation detection device, the speed detection device being configured to detect a rotating condition of a wheel of an electric bicycle, the rotation detection device being configured to detect a rotating condition of a power train, the power train being configured to rotate the wheel of the electric bicycle,the bicycle control device comprising: a rotational frequency detection unit configured to calculate, based on a result of detection by the rotation detection device, a rotational frequency of the power train.

<CIT> describes an electric bicycle comprising a pedal rotational speed detecting part, a driving wheel rotational speed detecting part, a motor, and a control part. The pedal rotational speed detecting part detects the rotational speed of a pedal. The driving wheel rotational speed detecting part detects the rotational speed of a driving wheel. The motor drives the driving wheel. The control part controls the motor by using control signals generated by the superposition of power control signals and speed control signals.

<CIT> describes a motor control system of an electric bike, including: a driving speed detection unit detecting a driving speed; a wheel speed detection unit detecting a rotational speed of a wheel; and a motor driving control unit controlling a driving of a motor, in which the motor driving control unit receives values detected by the driving speed detection unit and the wheel speed detection unit to estimate a chain gear ratio so as to control a driving of the motor.

<CIT> describes an electrically assisted bicycle having an electric motor which applies walk-push assisting torque to a rear wheel of the bicycle when a rider propels the bicycle by pushing it while walking, a motor control module configured to execute a first mode in which the electric motor applies no torque to the rear wheel, a second mode in which the electric motor applies to the rear wheel stay assisting torque which allows the electrically assisted bicycle to stay in a position where the rider wants to stay and a third mode in which the electric motor applies walk-push assisting torque to the rear wheel, wherein the first mode, the second mode and the third mode can be selected by using an operating unit which can be operated by the rider.

In view of the foregoing background, it is therefore an object of the present disclosure to provide a bicycle control device, a motor unit, a drive unit, an electric bicycle, and a program, all of which are configured or designed to detect the speed of the electric bicycle highly accurately. This object is solved by the subject-matter according to the independent claims. Additional embodiments are defined in the dependent claims.

A bicycle control device according to an aspect of the present disclosure is designed to be used with a speed detection device and a rotation detection device. The speed detection device detects a rotating condition of a wheel of an electric bicycle. The rotation detection device detects a rotating condition of a power train at shorter detection intervals than detection intervals of the speed detection device. The power train rotates the wheel of the electric bicycle. The bicycle control device includes a rotational frequency detection unit, an angle of rotation detection unit, a gear position estimation unit, and a speed calculation unit. The rotational frequency detection unit calculates, based on a result of detection by the rotation detection device, a rotational frequency of the power train. The angle of rotation detection unit calculates, based on the result of detection by the rotation detection device, an angle of rotation of the power train when the wheel turns to a predetermined angle of rotation. The gear position estimation unit estimates, when the rotating condition of the wheel is detected by the speed detection device, a gear position of a transmission of the electric bicycle based on the angle of rotation calculated by the angle of rotation detection unit. The speed calculation unit calculates a speed of the electric bicycle based on the rotational frequency calculated by the rotational frequency detection unit and the gear position estimated by the gear position estimation unit.

A motor unit according to another aspect of the present disclosure includes: the bicycle control device described above; and a motor. The motor applies rotational power to the wheel of the electric bicycle.

A drive unit according to still another aspect of the present disclosure includes: the motor unit described above; and a battery. The battery supplies power to the motor unit.

An electric bicycle according to yet another aspect of the present disclosure includes the motor unit described above, a frame, and the wheel. To the frame, the motor unit is attached. The wheel is mounted on the frame and turns with motive power supplied from the motor unit.

A program according to yet another aspect of the present disclosure is designed to cause a computer for use with a speed detection device and a rotation detection device to function as a rotational frequency detection unit, an angle of rotation detection unit, a gear position estimation unit, and a speed calculation unit. The speed detection device detects a rotating condition of a wheel of an electric bicycle. The rotation detection device detects, at shorter detection intervals than detection intervals of the speed detection device, a rotating condition of a power train to rotate the wheel of the electric bicycle. The rotational frequency detection unit calculates, based on a result of detection by the rotation detection device, a rotational frequency of the power train. The angle of rotation detection unit calculates, based on the result of detection by the rotation detection device, an angle of rotation of the power train when the wheel turns to a predetermined angle of rotation. The gear position estimation unit estimates, when the rotating condition of the wheel is detected by the speed detection device, a gear position of a transmission of the electric bicycle based on the angle of rotation calculated by the angle of rotation detection unit. The speed calculation unit calculates a speed of the electric bicycle based on the rotational frequency calculated by the rotational frequency detection unit and the gear position estimated by the gear position estimation unit.

A bicycle control device <NUM>, an electric bicycle <NUM>, a motor unit <NUM>, and a drive unit <NUM> according to an exemplary embodiment will be described with reference to the accompanying drawings. <FIG> to be referred to in the following description of embodiments is a schematic representation in which the ratio of the dimensions (including thicknesses) of respective constituent elements does not always reflect their actual dimensional ratio.

Also, in the following description, the traveling surface <NUM> is supposed to be a horizontal plane unless otherwise stated. Actually, however, the traveling surface <NUM> does not have to be a horizontal plane but may also be sloped with respect to the horizontal plane or a surface with unevenness.

Furthermore, in the following description, the direction in which the electric bicycle <NUM> travels is herein defined as a "forward direction" and the opposite direction thereof is herein defined as a "reverse direction. " Also, the forward direction and the reverse direction are herein collectively defined as "forward/backward directions" and two opposite directions that are perpendicular to the forward/backward directions and aligned with a horizontal plane are herein defined as "rightward/leftward directions. " Note that the definitions of these directions should not be construed as limiting the mode of use of the bicycle control device <NUM>, the motor unit <NUM>, the drive unit <NUM>, and the electric bicycle <NUM>. Furthermore, the arrows indicating the directions on the drawing are just shown there as an assistant to description and are insubstantial ones.

An overall configuration for a bicycle control device <NUM> according to an exemplary embodiment will be described with reference to <FIG>.

As shown in <FIG>, the bicycle control device <NUM> according to this embodiment includes a rotational frequency detection unit <NUM>, an angle of rotation detection unit <NUM>, a gear position estimation unit <NUM>, a speed calculation unit <NUM>, a drive control unit <NUM>, and a storage unit <NUM>.

The bicycle control device <NUM> may be implemented as, for example, a microprocessor including a processor and a memory. The processor performs the functions of the rotational frequency detection unit <NUM>, the angle of rotation detection unit <NUM>, the gear position estimation unit <NUM>, the speed calculation unit <NUM>, and the drive control unit <NUM> by executing a program stored in the memory. The program is designed to cause a computer used along with a speed detection device <NUM> and a rotation detection device <NUM> to perform the functions of the rotational frequency detection unit <NUM>, the angle of rotation detection unit <NUM>, the gear position estimation unit <NUM>, the speed calculation unit <NUM>, and the drive control unit <NUM>.

The bicycle control device <NUM> may be used in, for example, an electric bicycle <NUM> (see <FIG>). In particular, the bicycle control device <NUM> may be used along with the speed detection device <NUM> and rotation detection device <NUM> to be described later.

The electric bicycle <NUM> is a bicycle with the ability to travel on the traveling surface <NUM> with electro-motive power as shown in <FIG>. In this embodiment, the electric bicycle <NUM> is implemented as an electric assist bicycle (also called an "electric assisted bicycle") designed to make a motor <NUM> (see <FIG>) assist the user in his or her pedaling (where the force that the user applies for the purpose of pedaling will be hereinafter referred to as "pedaling force").

The electric bicycle <NUM> includes a motor unit <NUM> and a frame <NUM> as shown in <FIG>. The electric bicycle <NUM> further includes a plurality of (e.g., two in the example illustrated in <FIG>) wheels <NUM>, a fork <NUM>, handlebars <NUM>, a saddle <NUM>, a pair of crankarms <NUM>, a pair of pedals <NUM>, a power transmitter <NUM>, and a battery <NUM>. The motor unit <NUM> and the battery <NUM> together form a drive unit <NUM>.

The plurality of wheels <NUM> are members to support the frame <NUM> on the traveling surface <NUM>. The electric bicycle <NUM> according to this embodiment includes, as the plurality of wheels <NUM>, a front wheel <NUM> and a rear wheel <NUM>. The front wheel <NUM> has a hub <NUM> at its center and the rear wheel <NUM> has a hub <NUM> at its center.

The front wheel <NUM> is the front one of the two wheels <NUM> that are arranged in the forward/backward directions. In this embodiment, the front wheel <NUM> is supported by a pair of legs <NUM> so as to be rotatable around an axle aligned with the rightward/leftward directions. In this embodiment, the front wheel <NUM> is a wheel to which no electro-motive power is transmitted from the motor unit <NUM>.

The rear wheel <NUM> is the rear one of the two wheels <NUM> that are arranged in the forward/backward directions. In this embodiment, the rear wheel <NUM> is supported by two chain stays <NUM> so as to be rotatable around an axle aligned with the rightward/leftward directions.

The rear wheel <NUM> includes a rear sprocket <NUM>, which is concentric with, and mounted integrally with, the hub <NUM>. The rear sprocket <NUM> is coupled to a drive sprocket <NUM> of the motor unit <NUM> via the power transmitter <NUM>. Thus, the motive power output from the motor unit <NUM> is transmitted to the rear wheel <NUM>. The rear sprocket <NUM> may be made up of, for example, a plurality of sprockets.

The fork <NUM> supports the front wheel <NUM>. The fork <NUM> includes a pair of legs <NUM>, a crown <NUM>, and a steering column <NUM>. The crown <NUM> connects the respective upper ends of the pair of legs <NUM> together. The steering column <NUM> protrudes from the crown <NUM>. The front wheel <NUM> is mounted rotatably onto the pair of legs <NUM> via an axle passed through the hub <NUM>. The axis of rotation of the front wheel <NUM> is parallel to the traveling surface <NUM>. The protrusion axis (longitudinal axis) of the steering column <NUM> extends from the crown <NUM> so as to slope diagonally up toward the rear end of the electric bicycle <NUM> and is inclined with respect to the traveling surface <NUM>.

The handlebars <NUM> are attached to the upper end of the steering column <NUM> and fixed to the fork <NUM>. The steering column <NUM> is passed through a head tube <NUM> of a frame <NUM> as will be described later and is mounted rotatably to the frame <NUM>. The axis of rotation of the steering column <NUM> is generally parallel to the longitudinal axis of the steering column <NUM>. This allows the handlebars <NUM> to turn the front wheel <NUM> around an axis aligned with the longitudinal axis of the steering column <NUM> as its axis of rotation.

The frame <NUM> is a framework on which the plurality of wheels <NUM>, the fork <NUM>, the handlebars <NUM>, the saddle <NUM>, the battery <NUM>, and the motor unit <NUM> are mounted. In this embodiment, the frame <NUM> is made of an aluminum alloy including aluminum as a main component. However, this is only an example and should not be construed as limiting. Alternatively, the frame <NUM> may also be made of a metal such as iron, chromium molybdenum steel, high tensile strength steel, titanium, or magnesium, for example. Furthermore, the frame <NUM> does not have to be made of a metal but may also be made of carbon, wood, bamboo, or a fiber reinforced synthetic resin (such as carbon fiber reinforced plastics (CFRP)).

The frame <NUM> according to this embodiment includes a head tube <NUM>, a top tube <NUM>, a reinforcing tube <NUM>, a down tube <NUM>, a seat tube <NUM>, a plurality of (only one of which is shown in <FIG>) seat stays <NUM>, a plurality of (e.g., two in this example) chain stays <NUM>, and a bracket <NUM>. As used herein, the "tubes" refer to elongate and hollow members. For example, the tubes according to the present disclosure may have a round cross section such as a circular or oval (e.g., elliptical) cross section but may also have a rectangular (including square), hexagonal, or octagonal cross section.

The head tube <NUM> is a tube that supports the fork <NUM>. The center axis of the head tube <NUM> is inclined with respect to the traveling surface <NUM> so as to slope diagonally up toward the rear end of the electric bicycle <NUM>. The steering column <NUM> is passed through the head tube <NUM> such that the center axis of the head tube <NUM> is aligned with the center axis of the steering column <NUM>. This allows the head tube <NUM> to rotatably support the steering column <NUM>. In this embodiment, the axis of rotation of the steering column <NUM> is aligned with the enter axis of the head tube <NUM>.

The top tube <NUM> connects the head tube <NUM> to the seat tube <NUM>. The front end along the longitudinal axis of the top tube <NUM> is connected to the head tube <NUM>. The rear end along the longitudinal axis of the top tube <NUM> is connected to the seat tube <NUM>. The longitudinal axis of the top tube <NUM> is inclined with respect to the traveling surface <NUM> so as to slope diagonally down toward the rear end of the electric bicycle <NUM>. However, this is only an example and should not be construed as limiting. Alternatively, the top tube <NUM> does not have to be inclined with respect to the traveling surface <NUM>. Optionally, the electric bicycle <NUM> according to the present disclosure does not have to include the top tube <NUM>.

The reinforcing tube <NUM> is a reinforcing member to reinforce a connecting portion between the seat tube <NUM> and the top tube <NUM>. The reinforcing tube <NUM> connects the seat tube <NUM> to the top tube <NUM>. Alternatively, the electric bicycle <NUM> according to the present disclosure may include no reinforcing tubes <NUM>.

The seat tube <NUM> is a tube to hold the saddle <NUM>. The lower end along the longitudinal axis of the seat tube <NUM> is connected to the bracket <NUM>. The center axis of the seat tube <NUM> is inclined with respect to the traveling surface <NUM> so as to slope diagonally up from the lower end toward the rear end of the electric bicycle <NUM>. The rear end along the longitudinal axis of the top tube <NUM> is connected to a middle portion of the seat tube <NUM>. As used herein, the "middle portion of the seat tube <NUM>" refers to a portion, excluding the lower and upper ends along the longitudinal axis, of the seat tube <NUM>. Alternatively, according to the present disclosure, the top tube <NUM> may be connected to the upper end of the seat tube <NUM>.

The down tube <NUM> is a tube connecting the bracket <NUM> and the head tube <NUM> together. The front end along the longitudinal axis of the down tube <NUM> is connected to the head tube <NUM>. The rear end along the longitudinal axis of the down tube <NUM> is connected to the bracket <NUM>. The center axis of the down tube <NUM> is inclined with respect to the horizontal plane so as to slope diagonally up from the rear end along the longitudinal axis thereof toward the front end of the electric bicycle <NUM>. In this embodiment, the battery <NUM> is attached removably to the down tube <NUM>.

The plurality of chain stays <NUM> support the axle of the rear wheel <NUM>. The front end along the longitudinal axis of each chain stay <NUM> is connected to the bracket <NUM>. The rear end along the longitudinal axis of each chain stay <NUM> is connected to the rear end of an associated seat stay <NUM>. The pair of chain stays <NUM> are spaced from each other in the rightward/leftward directions and the rear wheel <NUM> is mounted rotatably onto the respective rear ends of the pair of chain stays <NUM> via the axle passed through the hub <NUM>. The axis of rotation of the rear wheel <NUM> is generally parallel to the traveling surface <NUM> and is aligned with the center axis of the axle that supports the rear wheel <NUM>.

The plurality of seat stays <NUM> connect the chain stays <NUM> to the seat tube <NUM>. In this embodiment, the rear end along the longitudinal axis of each seat stay <NUM> is connected to the rear end along the longitudinal axis of an associated chain stay <NUM>. The front end along the longitudinal axis of each seat stay <NUM> is connected to a middle portion of the seat tube <NUM>. In this embodiment, the pair of seat stays <NUM> branches from, and is integrated with, the top tube <NUM>. However, this is only an example and should not be construed as limiting. Alternatively, the seat stays <NUM> and the top tube <NUM> may be provided separately from each other.

The bracket <NUM> is a member to which the motor unit <NUM> is mounted. In this embodiment, the bracket <NUM> is formed in a generally C-shape when viewed from a direction perpendicular to both the upward/downward directions and the forward/backward directions. To the bracket <NUM>, connected are the rear end along the longitudinal axis of the down tube <NUM>, the lower end along the longitudinal axis of the seat tube <NUM>, and the respective front ends along the longitudinal axis of the chain stays <NUM>. This allows the rear end along the longitudinal axis of the down tube <NUM>, the lower end along the longitudinal axis of the seat tube <NUM>, and the respective front ends along the longitudinal axis of the chain stays <NUM> to be fixed to each other.

The saddle <NUM> includes a seat post <NUM> and a portion <NUM> that allows the rider to be seated thereon. The seat post <NUM> is passed through the seat tube <NUM> to extend along the center axis of the seat tube <NUM>. The seat post <NUM> protrudes downward from the portion <NUM> of the saddle <NUM> that allows the rider to be seated. In this embodiment, the seat post <NUM> is inclined with respect to the traveling surface <NUM> so as to slope diagonally down toward the front end of the electric bicycle <NUM>. The seat post <NUM> is attached to the seat tube <NUM> so as to be movable along the center axis of the seat tube <NUM>.

Each of the pedals <NUM> is attached to one longitudinal end, opposite from the other end facing the bottom bracket axle <NUM>, of an associated crankarm <NUM>. The pedals <NUM> are attached rotatably to the crankarms <NUM>. The axis of rotation of the pedals <NUM> is generally parallel to the axis of rotation of the bottom bracket axle <NUM>.

The power transmitter <NUM> transmits the motive power supplied from the motor unit <NUM> to at least one of the plurality of wheels <NUM>. In this embodiment, the power transmitter <NUM> is implemented as a chain provided to transmit motive power between the drive sprocket <NUM> of the motor unit <NUM> and the rear sprocket <NUM> of the rear wheel <NUM>. However, this is only an example and should not be construed as limiting. Alternatively, the power transmitter <NUM> may also be configured as a belt, a shaft, a wire, or a gear, for example.

As shown in <FIG>, the motor unit <NUM> includes the bicycle control device <NUM>, the speed detection device <NUM>, the rotation detection device <NUM>, the motor <NUM>, the bottom bracket axle <NUM> (see <FIG>), and the drive sprocket <NUM> (see <FIG>). The motor unit <NUM> is a device configured to output drive assist power. As shown in <FIG>, in this embodiment, the motor unit <NUM> transmits the pedaling force as human driving force, along with the drive assist power, to the rear wheel <NUM> via the power transmitter <NUM>.

As shown in <FIG>, to the bottom bracket axle <NUM> of the motor unit <NUM>, attached are the pair of crankarms <NUM>. The longitudinal axis of the crankarms <NUM> intersects (at right angles in the example illustrated in <FIG>) with the axis of rotation of the bottom bracket axle <NUM>. The pair of crankarms <NUM> are aligned with each other when viewed along the axis of rotation of the bottom bracket axle <NUM>.

The drive sprocket <NUM> may be made up of a plurality of sprockets, for example. The drive sprocket <NUM> and the rear sprocket <NUM> together form a transmission (gearbox). The electric bicycle <NUM> may have its gear shifted by changing the gear position of this transmission. As used herein, the "gear position" in a bicycle with multiple gear stages refers to a combination of a sprocket in the drive sprocket <NUM> and a sprocket in the rear sprocket <NUM>. For example, supposing the drive sprocket <NUM> has m sprockets and the rear sprocket <NUM> has n sprockets, the number of gear positions is m × n. For example, if the electric bicycle <NUM> has <NUM> gear stages, there are twenty gear positions.

The motor <NUM> shown in <FIG> is configured to apply rotational power to the wheel <NUM> of the electric bicycle <NUM> (see <FIG>). The motor <NUM> is provided near the bottom bracket axle <NUM> of the electric bicycle <NUM> (see <FIG>). The motor <NUM> is driven with the power supplied from the battery <NUM> to transmit the motive power to the bottom bracket axle <NUM>.

The speed detection device <NUM> detects the rotating condition of the wheel <NUM> of the electric bicycle <NUM> (see <FIG>). In this embodiment, the speed detection device <NUM> detects the rotating condition of the rear wheel <NUM> of the electric bicycle <NUM> (see <FIG>). As shown in <FIG>, the speed detection device <NUM> includes a magnet <NUM> and a speed sensor <NUM>. The magnet <NUM> is provided for the rear wheel <NUM> and rotates along with the rear wheel <NUM>. Alternatively, the speed detection device <NUM> may detect the rotating condition of the front wheel <NUM> of the electric bicycle <NUM> (see <FIG>). In that case, the magnet <NUM> is provided for the front wheel <NUM> and rotates along with the front wheel <NUM>.

The speed sensor <NUM> is a hole IC for detecting the magnetic force of the magnet provided for the rear wheel <NUM>. The speed sensor <NUM> may be provided, for example, for one of the chain stays <NUM> of the frame <NUM> (see <FIG>). The speed sensor <NUM> detects the magnetic force of the magnet <NUM> provided for the rear wheel <NUM> by using a hole effect. The speed sensor <NUM> outputs an electrical signal based on the result of detection to the bicycle control device <NUM>. In this embodiment, the speed detection device <NUM> detects the rotating condition of the rear wheel <NUM> once every time the rear wheel <NUM> makes one full rotation.

The rotation detection device <NUM> is a motor rotation detection device for detecting the rotating condition of the motor <NUM>. As shown in <FIG>, the rotation detection device <NUM> according to this embodiment includes a rotary member <NUM> and a rotation sensor <NUM>.

The rotary member <NUM> is mounted on an outer peripheral surface of an output shaft <NUM> of the motor <NUM> and rotates along with the output shaft <NUM>. Thus, the axis of rotation of the rotary member <NUM> is the same as the axis of rotation of the output shaft <NUM>. The rotary member <NUM> may be implemented as either a member with a plurality of magnets which are embedded along the circumference of the rotary member <NUM> such that the magnetic polarities change alternately along the circumference or a magnet which is magnetized such that the magnetic polarities change alternately along the circumference.

The rotation sensor <NUM> is a hole IC for detecting the magnetic force of the magnet(s) of the rotary member <NUM>. The rotation sensor <NUM> is provided to face the rotary member <NUM>. The rotation sensor <NUM> outputs an electrical signal, representing a variation caused in magnetic field by the rotation of the rotary member <NUM>, to the bicycle control device <NUM>.

The rotation detection device <NUM> detects the rotating condition of the motor <NUM> at shorter detection intervals than detection intervals of the speed detection device <NUM>. In other words, the rotation detection device <NUM> has a higher resolution than the speed detection device <NUM>. For example, if the speed detection device <NUM> detects one rotating condition of the wheel <NUM>, then the rotation detection device <NUM> detects the rotating condition of the motor <NUM> at an interval shorter than the time it takes for the wheel <NUM> to make one full rotation. Typically, while the wheel <NUM> makes one full rotation, the rotation detection device <NUM> detects the rotating condition of the motor <NUM> multiple times.

As shown in <FIG>, the drive unit <NUM> includes the motor unit <NUM> and a battery <NUM>.

The battery <NUM> supplies power to the motor unit <NUM>. More specifically, the battery <NUM> supplies power to the motor <NUM> of the motor unit <NUM> (see <FIG>). In addition, the battery <NUM> supplies power to not only the motor <NUM> but also a headlight and an ON/OFF switch of the motor <NUM> as well. The battery <NUM> is attached removably to the down tube <NUM>. Alternatively, the battery <NUM> may also be arranged behind and along the seat tube <NUM>.

Next, respective components of the bicycle control device <NUM> will be described with reference to <FIG>.

The rotational frequency detection unit <NUM> calculates, based on the result of detection by the rotation detection device <NUM>, a rotational frequency of the motor <NUM>. As used herein, the rotational frequency of the motor <NUM> refers to the number of revolutions of the motor <NUM> per unit time (e.g., one second).

In addition, the rotational frequency detection unit <NUM> determines, based on the result of detection by the rotation detection device <NUM>, whether or not the motor <NUM> is running. This enables determining whether the motor <NUM> is running or at a stop.

The angle of rotation detection unit <NUM> calculates, based on the result of detection by the rotation detection device <NUM>, the angle of rotation of the motor <NUM> when the wheel <NUM> turns to a predetermined angle of rotation. The angle of rotation detection unit <NUM> detects the angle of rotation of the motor <NUM> every time the rotating condition of the motor <NUM> is detected by the rotation detection device <NUM>. That is to say, the angle of rotation detection unit <NUM> detects the angle of rotation of the motor <NUM> at shorter detection intervals than detection intervals of the speed detection device <NUM>. Information about the angle of rotation detected by the angle of rotation detection unit <NUM> is stored in the storage unit <NUM>.

The gear position estimation unit <NUM> estimates (calculates), when the rotating condition of the wheel <NUM> (see <FIG>) is detected by the speed detection device <NUM>, the gear position of the transmission of the electric bicycle <NUM> based on the angle of rotation calculated by the angle of rotation detection unit <NUM>. After having estimated the gear position of the transmission, the gear position estimation unit <NUM> updates the information, stored in the storage unit <NUM>, about the gear position.

The gear position estimation unit <NUM> has the capability of checking the detection by the speed detection device <NUM>. More specifically, the gear position estimation unit <NUM> checks the detection by the speed detection device <NUM> within a predetermined period of time since the last detection by the speed detection device <NUM>. In a normal condition, the speed detection device <NUM> detects the rotating condition of the wheel <NUM> every time the wheel <NUM> makes one full rotation, as described above. Therefore, in the normal condition, the gear position estimation unit <NUM> acquires the result of detection by the speed detection device <NUM> every time the wheel <NUM> makes one full rotation. On the other hand, in an abnormal condition (e.g., when the magnet of the speed detection device <NUM> has come off the wheel <NUM>), the gear position estimation unit <NUM> cannot acquire the result of detection by the speed detection device <NUM> even when the wheel <NUM> makes one full rotation.

On acquiring the result of detection by the speed detection device <NUM>, the gear position estimation unit <NUM> estimates, based on the angle of rotation, measured by the angle of rotation detection unit <NUM>, of the motor <NUM>, the gear position of the transmission. The gear position estimation unit <NUM> estimates the gear position by reference to information about the correspondence between the angle of rotation and the gear position. The information about the correspondence is stored in advance in the storage unit <NUM>. The gear position estimation unit <NUM> acquires, from the storage unit <NUM>, not only information about the latest angle of rotation detected by the angle of rotation detection unit <NUM> but also information about the gear position corresponding to the latest angle of rotation, thereby estimating the gear position of the transmission.

This allows the gear position of the transmission to be estimated even without a sensor for detecting the actual gear position. In addition, even if the electric bicycle <NUM> is traveling at so low speeds that it takes some time for the wheel <NUM> to make one rotation, the speed calculation unit <NUM> (to be described later) may accurately estimate the speed of the electric bicycle <NUM> by using the angle of rotation of the motor <NUM> when the wheel <NUM> makes one full rotation.

Note that the gear position estimation unit <NUM> estimates the gear position of the transmission only when the speed of the electric bicycle <NUM> is equal to or lower than <NUM> kilometers per hour. Meanwhile, if the speed of the electric bicycle <NUM> is higher than <NUM> kilometers per hour, the gear position estimation unit <NUM> does not estimate the gear position as described above. More specifically, the gear position estimation unit <NUM> may selectively enable or disable the gear position estimation capability. When the speed of the electric bicycle <NUM> is equal to or lower than <NUM> kilometers per hour, the gear position estimation unit <NUM> enables the gear position estimation capability. On the other hand, when the speed of the electric bicycle <NUM> is higher than <NUM> kilometers per hour, the gear position estimation unit <NUM> disables the gear position estimation capability. Note that the threshold speed at or under which the gear position estimation capability is enabled does not have to be <NUM> kilometers per hour but may also be any other prescribed speed. Even so, the gear position estimation unit <NUM> enables the gear position estimation capability when finding the speed of the electric bicycle <NUM> equal to or lower than the prescribed speed but disenables the gear position estimation capability when finding the speed of the electric bicycle <NUM> higher than the prescribed speed.

Optionally, the gear position estimation unit <NUM> may enable the gear position estimation capability when a walk-a-bicycle button is pressed. Specifically, when finding the walk-a-bicycle button pressed, the gear position estimation unit <NUM> estimates the gear position of the transmission of the electric bicycle <NUM> based on the angle of rotation calculated by the angle of rotation detection unit <NUM>.

If no detection is made by the speed detection device <NUM> within a predetermined period of time, the gear position estimation unit <NUM> checks the speed detection device <NUM> for malfunctions. More specifically, the gear position estimation unit <NUM> checks the speed detection device <NUM> for malfunctions by determining whether or not a rotational ratio, representing the angle of rotation of the motor <NUM> since the last detection made by the speed detection device <NUM>, is equal to or greater than a prescribed value.

The prescribed value is a value defined based on the angle of rotation of the motor <NUM> while the wheel <NUM> makes one full rotation in a normal condition. That is to say, the prescribed value is a value defined based on the angle of rotation of the motor <NUM> since the last detection made by the speed detection device <NUM> in the normal condition. Specifically, the prescribed value is set at a value larger than the angle of rotation of the motor <NUM> in the normal condition. That is to say, the prescribed value is set at a value with some margin allowed with respect to the angle of rotation of the motor <NUM> in the normal condition.

When the rotational ratio is equal to or greater than the prescribed value, the magnet of the speed detection device <NUM> could drop to prevent the rotating condition of the wheel <NUM> from being detected. Therefore, when the rotational ratio is equal to or greater than the prescribed value, the gear position estimation unit <NUM> estimates (sets) the gear position of the transmission at the highest stage (i.e., top gear). Estimating the gear position of the transmission at the highest stage prevents the speed limit from being exceeded because the estimated speed is higher than the actual speed.

Meanwhile, if the rotational ratio is less than the prescribed value, then the wheel <NUM> may be turning so slowly that no detection has been made by the speed detection device <NUM> yet. Thus, the gear position estimation unit <NUM> continues checking detection by the speed detection device <NUM>.

The speed calculation unit <NUM> calculates the speed of the electric bicycle <NUM> based on the rotational frequency calculated by the rotational frequency detection unit <NUM> and the gear position estimated by the gear position estimation unit <NUM>. As used herein, the speed of the electric bicycle <NUM> is the product of the circumferential length of the wheel <NUM>, the rotational frequency of the motor <NUM>, and the rotational ratio. The circumferential length of the wheel <NUM> is a known value, which is stored in advance in the storage unit <NUM>. The rotational ratio is stored in advance in the storage unit <NUM> in association with the gear position of the transmission. The speed calculation unit <NUM> acquires information about the rotational ratio, corresponding to the gear position estimated by the gear position estimation unit <NUM>, from the storage unit <NUM>. In addition, the speed calculation unit <NUM> also acquires information about the circumferential length of the wheel <NUM> from the storage unit <NUM>. The speed calculation unit <NUM> calculates, as the speed of the electric bicycle <NUM>, the product of the wheel's <NUM> circumferential length acquired from the storage unit <NUM>, the rotational frequency detected by the rotational frequency detection unit <NUM>, and the rotational ratio acquired from the storage unit <NUM>.

The drive control unit <NUM> controls the motor <NUM>. More specifically, the drive control unit <NUM> controls the motor <NUM> by calculating, based on the speed calculated by the speed calculation unit <NUM>, a rotational velocity associated with the speed and outputting a drive control signal to the motor <NUM> such that the motor <NUM> rotates at the rotational velocity calculated. For example, the drive control unit <NUM> controls the motor <NUM> such that the motor <NUM> assists the user at the speed calculated by the speed calculation unit <NUM>.

The storage unit <NUM> stores information about the circumferential length of the wheel <NUM> of the electric bicycle <NUM>. In addition, the storage unit <NUM> also stores information about the correspondence between the rotational ratio and the gear position of the transmission. Moreover, the storage unit <NUM> further stores information about the gear position estimated by the gear position estimation unit <NUM>. The information about the gear position estimated by the gear position estimation unit <NUM> is updated every time the gear position is estimated by the gear position estimation unit <NUM>.

Next, it will be described with reference to <FIG> how the bicycle control device <NUM> performs the operation of estimating the gear position of the transmission (i.e., how the bicycle control device <NUM> carries out a bicycle control method).

First, the rotational frequency detection unit <NUM> determines, based on the result of detection by the rotation detection device <NUM>, whether the motor <NUM> is running or not (in Step S1). If it turns out in Step S1 that the motor <NUM> is not running (if the answer is NO in Step S1), then the electric bicycle <NUM> is traveling downhill and the motor <NUM> is not running, and therefore, the operation of estimating the gear position of the transmission ends. On the other hand, if the rotational frequency detection unit <NUM> finds, in Step S1, the motor <NUM> running (if the answer is YES in Step S1), then the gear position estimation unit <NUM> checks whether there is any detection made by the speed detection device <NUM> (in Step S2).

If there is any detection made by the speed detection device <NUM> (if the answer is YES in Step S3), then the angle of rotation detection unit <NUM> starts measuring the angle of rotation of the motor <NUM> (in Step S4). The angle of rotation detection unit <NUM> measures, based on the result of detection by the rotation detection device <NUM>, the angle of rotation of the motor <NUM> while the wheel <NUM> makes one full rotation. Thereafter, the gear position estimation unit <NUM> estimates (sets) the gear position of the transmission at a temporary position (in Step S5). Then, the gear position estimation unit <NUM> updates the gear position information to be stored in the storage unit <NUM> (in Step S6).

The gear position estimation unit <NUM> checks whether there is any detection made by the speed detection device <NUM> (in Step S7) within a predetermined period of time since the last detection made by the speed detection device <NUM> (in Step S3, for example). If there is any detection made by the speed detection device <NUM> within the predetermined period of time (if the answer is YES in Step S8), the gear position estimation unit <NUM> estimates the gear position of the transmission (in Step S9). Thereafter, the gear position estimation unit <NUM> updates the gear position information to be stored in the storage unit <NUM> (in Step S10).

Thereafter, if it turns out that the motor <NUM> is running (if the answer is YES in Step S11), the process goes back to the processing step S7. On the other hand, if it turns out that the motor <NUM> is at a stop (if the answer is NO in Step S11), then the operation of estimating the gear position of the transmission ends.

Meanwhile, if it turns out in Step S8 that there is no detection made by the speed detection device <NUM> within the predetermined period of time (if the answer is NO in Step S8), then the gear position estimation unit <NUM> checks the speed detection device <NUM> for malfunctions (in Step S <NUM>). When finding the rotational ratio, representing the angle of rotation of the motor <NUM> since the last detection made by the speed detection device <NUM>, equal to or greater than the prescribed value (if the answer is YES in Step S13), the gear position estimation unit <NUM> estimates (or sets) the gear position of the transmission at the highest stage (top gear) (in Step S14). Thereafter, the gear position estimation unit <NUM> updates the gear position information to be stored in the storage unit <NUM> (in Step S <NUM>). On the other hand, if the rotational ratio turns out in Step S13 to be less than the prescribed value (if the answer is NO in Step S13), then the process goes back to the processing step S7, in which the gear position estimation unit <NUM> checks whether there is any detection made by the speed detection device <NUM>.

The bicycle control device <NUM> according to this embodiment calculates the angle of rotation of the motor <NUM> (power train) when the wheel <NUM> of the electric bicycle <NUM> turns to a predetermined angle of rotation and estimates the gear position of the transmission of the electric bicycle <NUM> based on the angle of rotation of the motor <NUM>. This allows the bicycle control device <NUM> according to this embodiment to calculate the speed of the electric bicycle <NUM> accurately enough even without a sensor for detecting the gear position when the gear position of the transmission changes.

In addition, the bicycle control device <NUM> according to this embodiment calculates the angle of rotation of the motor <NUM> based on the result of detection of the rotation of the motor <NUM> having a higher resolution than any other part. This allows the speed of the electric bicycle <NUM> to be calculated even more accurately.

Furthermore, the bicycle control device <NUM> according to this embodiment controls the motor <NUM> by using the speed calculated based on the gear position estimated. This allows the motor <NUM> to be controlled accurately enough even without a sensor for detecting the gear position of the transmission.

Furthermore, the bicycle control device <NUM> according to this embodiment makes the gear position estimation unit <NUM> estimate the gear position of the transmission at least when the speed of the electric bicycle <NUM> is equal to or lower than <NUM> kilometers per hour. Thus, the bicycle control device <NUM> according to this embodiment achieves the advantage of calculating the speed of the electric bicycle <NUM> even more accurately, particularly when the electric bicycle <NUM> is traveling at low speeds.

Next, variations of the exemplary embodiment described above will be enumerated one after another.

According to a first variation of the exemplary embodiment, the rotation detection device <NUM> does not have to detect the rotating condition of the motor <NUM>. Alternatively, the rotation detection device <NUM> may detect the rotating condition of the power train to rotate the wheel <NUM> of the electric bicycle <NUM>. The power train described above includes the rear sprocket <NUM>, the drive sprocket <NUM>, the bottom bracket axle <NUM>, and a pulley. As in the first embodiment described above, the rotation detection device <NUM> detects the rotating condition of the power train at shorter detection intervals than detection intervals of the speed detection device <NUM>. Then, the angle of rotation detection unit <NUM> calculates, based on the result of detection by the rotation detection device <NUM>, the angle of rotation of the motor <NUM> when the wheel <NUM> turns to a predetermined angle of rotation.

If the power train is the bottom bracket axle <NUM>, then the rotation detection device <NUM> is a bottom bracket axle rotation detection device for detecting the rotating condition of the bottom bracket axle <NUM>. In that case, the rotation detection device <NUM> includes a rotation dog (target of detection) and a bottom bracket axle rotation sensor. The rotation detection device <NUM> outputs an electrical signal detected by the bottom bracket axle rotation sensor to the bicycle control device <NUM> and makes the bicycle control device <NUM> perform processing, thereby detecting the rotating condition of the bottom bracket axle <NUM>.

The bottom bracket axle rotation sensor may be implemented as, for example, an optical sensor. The bottom bracket axle rotation sensor includes a light-emitting element (such as a light-emitting diode (LED) and a photosensitive element (such as a phototransistor). The light-emitting element and the photosensitive element are connected to the bicycle control device <NUM> so as to transmit and receive an electrical signal to/from the bicycle control device <NUM>. The rotation dog is provided between the light-emitting element and the photosensitive element. The bottom bracket axle rotation sensor emits light from the light-emitting element toward the photosensitive element. The photosensitive element receives light transmitted through a light-transmitting portion.

Nevertheless, this is only an exemplary configuration for the rotation detection device <NUM>. Alternatively, the rotation detection device <NUM> may use, for example, an annular ferrite magnet as the rotation dog and may use an electromagnetic rotation sensor for detecting a variation in magnetic field as the bottom bracket axle rotation sensor.

Note that when the angle of rotation of a member other than the motor <NUM> is used, the prescribed value varies according to the gear position of the transmission in Step S13 shown in <FIG>. Thus, the prescribed value is supposed to be a value corresponding to the gear position estimated by the gear position estimation unit <NUM> most lately. More specifically, the prescribed value is set at a value larger than the rotational frequency of the motor <NUM> in a normal condition at the gear position estimated most lately by the gear position estimation unit <NUM>.

According to a second variation of the exemplary embodiment, the gear position estimation unit <NUM> does not have to estimate the gear position of the transmission only when the speed of the electric bicycle <NUM> is equal to or lower than <NUM> kilometers per hour. Alternatively, the gear position estimation unit <NUM> may also estimate the gear position of the transmission even when the speed of the electric bicycle <NUM> is higher than <NUM> kilometers per hour. In other words, the gear position estimation unit <NUM> may estimate the gear position of the transmission at least when the speed of the electric bicycle <NUM> is equal to or lower than <NUM> kilometers per hour.

According to a third variation of the exemplary embodiment, the speed detection device <NUM> does not have to detect the rotating condition of the wheel <NUM> once, but may detect the rotating condition of the wheel <NUM> multiple times, every time the wheel <NUM> makes one full rotation. In the latter case, the speed detection device <NUM> includes a plurality of magnets. The plurality of magnets are provided at multiple different positions on the wheel <NUM>. The speed detection device <NUM> may detect the rotating condition of the wheel <NUM> once every time the wheel <NUM> makes a half rotation or a quarter rotation. Still alternatively, the speed detection device <NUM> may detect the rotating condition of the wheel <NUM> once, every time the wheel <NUM> makes a number of rotations. For example, the speed detection device <NUM> may detect the rotating condition of the wheel <NUM> once, every time the wheel <NUM> makes two full rotations.

According to a fourth variation of the exemplary embodiment, the drive control unit <NUM> may acquire, from a predefined table, for example, a rotational velocity corresponding to the speed calculated by the speed calculation unit <NUM>. In the fourth variation, the storage unit <NUM> stores, in the form of a table, for example, information about the correspondence between a plurality of speeds of the electric bicycle <NUM> and their corresponding rotational velocities of the motor <NUM>. In the table of correspondence stored in the storage unit <NUM>, a rotational velocity of the motor <NUM> is associated with each speed of the electric bicycle <NUM>. The drive control unit <NUM> extracts, from the table of correspondence stored in the storage unit <NUM>, a rotational velocity corresponding to the speed calculated by the speed calculation unit <NUM>. Then, the drive control unit <NUM> outputs a drive control signal to the motor <NUM> such that the motor <NUM> rotates at the rotational velocity extracted, thereby controlling the motor <NUM>.

In the exemplary embodiment described above, the motor unit <NUM> is implemented as a uniaxial drive unit. However, this is only an example and should not be construed as limiting. Alternatively, the motor unit <NUM> may also be implemented as a biaxial drive unit.

In the exemplary embodiment described above, the electric bicycle <NUM> is implemented as an electric assist bicycle designed to assist the user in pedaling with the motive power supplied from the motor <NUM>. According to a variation of the exemplary embodiment, the electric bicycle <NUM> may also be a bicycle in which a human driving system and a motor driving system are provided independently of each other. In other words, the electric bicycle <NUM> may also be a bicycle in which a drive system to apply motive power to the wheels <NUM> by pedaling (i.e., the human driving system) and a drive system to apply motive power to the wheel <NUM> from the motor <NUM> (i.e., the motor drive system) are provided independently of each other (i.e., a bicycle which may travel with only the motive power supplied from the motor <NUM>). In short, the electric bicycle <NUM> may be implemented as either an electric assist bicycle or a bicycle that may travel with only the motive power supplied from the motor <NUM>.

The electric bicycle <NUM> according to this embodiment is implemented as a bicycle with one front wheel <NUM> and one rear wheel <NUM>. According to a variation of the exemplary embodiment, the electric bicycle <NUM> may also be implemented as a tricycle having either one front wheel <NUM> and two rear wheels <NUM> or two front wheels <NUM> and one rear wheel <NUM>, whichever is appropriate. Still alternatively, the electric bicycle <NUM> may also be implemented as a quadricycle having two front wheels <NUM> and two rear wheels <NUM>.

The bicycle control device <NUM> according to any of these variations would achieve the same advantages as the bicycle control device <NUM> according to the exemplary embodiment.

Note that the embodiment and variations described above are only exemplary ones of various embodiments and variations of the present disclosure and should not be construed as limiting. Rather, the exemplary embodiment and variations may be readily modified in various manners depending on a design choice or any other factor without departing from the scope of the present disclosure.

The embodiment and its variations described above may be specific implementations of the following aspects of the present disclosure.

A bicycle control device (<NUM>) according to a first aspect is designed to be used with a speed detection device (<NUM>) and a rotation detection device (<NUM>). The speed detection device (<NUM>) detects a rotating condition of a wheel (<NUM>) of an electric bicycle (<NUM>). The rotation detection device (<NUM>) detects a rotating condition of a power train (including a motor <NUM>; a rear sprocket <NUM>; a drive sprocket <NUM>; and a bottom bracket axle <NUM>) at shorter detection intervals than detection intervals of the speed detection device (<NUM>). The power train rotates the wheel (<NUM>) of the electric bicycle (<NUM>). The bicycle control device (<NUM>) includes a rotational frequency detection unit (<NUM>), an angle of rotation detection unit (<NUM>), a gear position estimation unit (<NUM>), and a speed calculation unit (<NUM>). The rotational frequency detection unit (<NUM>) calculates, based on a result of detection by the rotation detection device (<NUM>), a rotational frequency of the power train. The angle of rotation detection unit (<NUM>) calculates, based on the result of detection by the rotation detection device (<NUM>), an angle of rotation of the power train when the wheel (<NUM>) turns to a predetermined angle of rotation. The gear position estimation unit (<NUM>) estimates, when the rotating condition of the wheel (<NUM>) is detected by the speed detection device (<NUM>), a gear position of a transmission (including the rear sprocket <NUM> and the drive sprocket <NUM>) of the electric bicycle (<NUM>) based on the angle of rotation calculated by the angle of rotation detection unit (<NUM>). The speed calculation unit (<NUM>) calculates a speed of the electric bicycle (<NUM>) based on the rotational frequency calculated by the rotational frequency detection unit (<NUM>) and the gear position estimated by the gear position estimation unit (<NUM>).

The bicycle control device (<NUM>) according to the first aspect may calculate the speed of the electric bicycle (<NUM>) accurately enough even without a sensor for detecting the gear position when the gear position of the transmission (including the rear sprocket <NUM> and the drive sprocket <NUM>) changes.

In a bicycle control device (<NUM>) according to a second aspect, which may be implemented in conjunction with the first aspect, the power train includes a motor (<NUM>). The angle of rotation detection unit (<NUM>) calculates, based on the result of detection by the rotation detection device (<NUM>), the angle of rotation of the motor (<NUM>) when the wheel (<NUM>) has the predetermined angle of rotation, as an angle of rotation of the power train.

The bicycle control device (<NUM>) according to the second aspect may calculate the speed of the electric bicycle (<NUM>) even more accurately.

A bicycle control device (<NUM>) according to a third aspect, which may be implemented in conjunction with the second aspect, further includes a drive control unit (<NUM>). The drive control unit (<NUM>) controls the motor (<NUM>) by calculating a rotational velocity associated with the speed calculated by the speed calculation unit (<NUM>) and by outputting a drive control signal to the motor (<NUM>) such that the motor (<NUM>) rotates at the rotational velocity thus calculated.

The bicycle control device (<NUM>) according to the third aspect may control the motor (<NUM>) accurately enough even without a sensor for detecting the gear position of the transmission (including the rear sprocket <NUM> and the drive sprocket <NUM>).

A bicycle control device (<NUM>) according to a fourth aspect, which may be implemented in conjunction with the second aspect, further includes a drive control unit (<NUM>). The drive control unit (<NUM>) controls the motor (<NUM>) by outputting a drive control signal to the motor (<NUM>) such that the motor (<NUM>) rotates at a rotational velocity associated with the speed calculated by the speed calculation unit (<NUM>).

The bicycle control device (<NUM>) according to the fourth aspect may control the motor (<NUM>) accurately enough even without a sensor for detecting the gear position of the transmission (including the rear sprocket <NUM> and the drive sprocket <NUM>).

A bicycle control device (<NUM>) according to a fifth aspect, which may be implemented in conjunction with the fourth aspect, further includes a storage unit (<NUM>). The storage unit (<NUM>) stores information about correspondence between each of a plurality of speeds of the electric bicycle (<NUM>) and an associated rotational velocity of the motor (<NUM>). The drive control unit (<NUM>) controls the motor (<NUM>) by extracting, by reference to the information about the correspondence as stored in the storage unit (<NUM>), the rotational velocity associated with the speed calculated by the speed calculation unit (<NUM>) and by outputting a drive control signal to the motor (<NUM>) such that the motor (<NUM>) rotates at the rotational velocity extracted.

In a bicycle control device (<NUM>) according to a sixth aspect, which may be implemented in conjunction with any one of the first to fifth aspects, the gear position estimation unit (<NUM>) estimates the gear position at least when the speed of the electric bicycle (<NUM>) is equal to or lower than <NUM> kilometers per hour.

The bicycle control device (<NUM>) according to the sixth aspect achieves the advantage of calculating the speed of the electric bicycle (<NUM>) even more accurately, particularly when the electric bicycle (<NUM>) is traveling at low speeds.

In a bicycle control device (<NUM>) according to a seventh aspect, which may be implemented in conjunction with any one of the first to sixth aspects, the gear position estimation unit (<NUM>) is configured to selectively enable or disable an estimation capability of estimating the gear position.

In a bicycle control device (<NUM>) according to an eighth aspect, which may be implemented in conjunction with the seventh aspect, the gear position estimation unit (<NUM>) enables the estimation capability when the speed of the electric bicycle (<NUM>) is equal to or lower than a prescribed speed and disables the estimation capability when the speed of the electric bicycle (<NUM>) is higher than the prescribed speed.

In a bicycle control device (<NUM>) according to a ninth aspect, which may be implemented in conjunction with the eighth aspect, the prescribed speed is <NUM> kilometers per hour.

In a bicycle control device (<NUM>) according to a tenth aspect, which may be implemented in conjunction with the seventh aspect, the gear position estimation unit (<NUM>) enables the estimation capability when finding a walk-a-bicycle button pressed.

A motor unit (<NUM>) according to an eleventh aspect includes: the bicycle control device (<NUM>) according to any one of the first to tenth aspects; and a motor (<NUM>). The motor (<NUM>) applies rotational power to the wheel (<NUM>) of the electric bicycle (<NUM>).

The motor unit (<NUM>) according to the eleventh aspect allows the bicycle control device (<NUM>) to calculate the speed of the electric bicycle (<NUM>) accurately enough even without a sensor for detecting the gear position when the gear position of the transmission (including the rear sprocket <NUM> and the drive sprocket <NUM>) changes.

A drive unit (<NUM>) according to a twelfth aspect includes: the motor unit (<NUM>) according to the eleventh aspect; and a battery (<NUM>). The battery (<NUM>) supplies power to the motor unit (<NUM>).

The drive unit (<NUM>) according to the twelfth aspect allows the bicycle control device (<NUM>) to calculate the speed of the electric bicycle (<NUM>) accurately enough even without a sensor for detecting the gear position when the gear position of the transmission (including the rear sprocket <NUM> and the drive sprocket <NUM>) changes.

An electric bicycle (<NUM>) according to a thirteenth aspect includes the motor unit (<NUM>) according to the eleventh aspect, a frame (<NUM>), and the wheel (<NUM>). To the frame (<NUM>), the motor unit (<NUM>) is attached. The wheel (<NUM>) is mounted on the frame (<NUM>) and turns with motive power supplied from the motor unit (<NUM>).

The electric bicycle (<NUM>) according to the thirteenth aspect allows the bicycle control device (<NUM>) to calculate the speed of the electric bicycle (<NUM>) accurately enough even without a sensor for detecting the gear position when the gear position of the transmission (including the rear sprocket <NUM> and the drive sprocket <NUM>) changes.

A program according to a fourteenth aspect is designed to cause a computer for use with a speed detection device (<NUM>) and a rotation detection device (<NUM>) to function as a rotational frequency detection unit (<NUM>), an angle of rotation detection unit (<NUM>), a gear position estimation unit (<NUM>), and a speed calculation unit (<NUM>). The speed detection device (<NUM>) detects a rotating condition of a wheel (<NUM>) of an electric bicycle (<NUM>). The rotation detection device (<NUM>) detects, at shorter detection intervals than detection intervals of the speed detection device (<NUM>), a rotating condition of a power train (including a motor <NUM>; a rear sprocket <NUM>; a drive sprocket <NUM>; and a bottom bracket axle <NUM>) to rotate the wheel (<NUM>) of the electric bicycle (<NUM>). The rotational frequency detection unit (<NUM>) calculates, based on a result of detection by the rotation detection device (<NUM>), a rotational frequency of the power train. The angle of rotation detection unit (<NUM>) calculates, based on the result of detection by the rotation detection device (<NUM>), an angle of rotation of the power train when the wheel (<NUM>) turns to a predetermined angle of rotation. The gear position estimation unit (<NUM>) estimates, when the rotating condition of the wheel (<NUM>) is detected by the speed detection device (<NUM>), a gear position of a transmission (including the rear sprocket <NUM> and the drive sprocket <NUM>) of the electric bicycle (<NUM>) based on the angle of rotation calculated by the angle of rotation detection unit (<NUM>). The speed calculation unit (<NUM>) calculates a speed of the electric bicycle (<NUM>) based on the rotational frequency calculated by the rotational frequency detection unit (<NUM>) and the gear position estimated by the gear position estimation unit (<NUM>).

Claim 1:
A bicycle control device (<NUM>) for use with a speed detection device (<NUM>) and a rotation detection device (<NUM>), the speed detection device (<NUM>) being configured to detect a rotating condition of a wheel (<NUM>) of an electric bicycle (<NUM>), the rotation detection device (<NUM>) being configured to detect a rotating condition of a power train at shorter detection intervals than detection intervals of the speed detection device (<NUM>), the power train being configured to rotate the wheel (<NUM>) of the electric bicycle (<NUM>),
the bicycle control device (<NUM>) comprising:
a rotational frequency detection unit (<NUM>) configured to calculate, based on a result of detection by the rotation detection device (<NUM>), a rotational frequency of the power train;
an angle of rotation detection unit (<NUM>) configured to calculate, based on the result of detection by the rotation detection device (<NUM>), an angle of rotation of the power train when the wheel (<NUM>) turns to a predetermined angle of rotation;
a gear position estimation unit (<NUM>) configured to, when the rotating condition of the wheel (<NUM>) is detected by the speed detection device (<NUM>), estimate a gear position of a transmission of the electric bicycle (<NUM>) based on the angle of rotation calculated by the angle of rotation detection unit (<NUM>); and
a speed calculation unit (<NUM>) configured to calculate a speed of the electric bicycle (<NUM>) based on the rotational frequency calculated by the rotational frequency detection unit (<NUM>) and the gear position estimated by the gear position estimation unit (<NUM>).