Patent Description:
An electric tool system used along with an electric tool adapter is conventionally known (for example, Document <NUM> (<CIT>)). The electric tool system described in Document <NUM> includes an electric tool adapter which enables a battery pack to be attached to an electric tool (an electric tool body). The electric tool adapter includes a DC-DC converter. The DC-DC converter is configured to be freely detachably attached to each of the electric tool and the battery pack. The DC-DC converter is configured to step up or step down a voltage of the battery pack to convert the voltage into a drive voltage of the electric tool, and the DC-DC converter is configured to supply the drive voltage to the electric tool. Thus, the electric tool system described in Document <NUM> enables the electric tool to satisfactorily operate even when a battery pack having a voltage different from the rated voltage of the electric tool is used.

In the electric tool system described in Document <NUM>, an electric tool adapter is indispensable when a battery pack having a voltage different from the rated voltage of the electric tool is used. However, different rated voltages of electric tools have different compatible electric tool adapters, and when an incompatible electric tool adapter is adopted, failure may occur in operation of the electric tool.

<CIT> describes a cordless power tool system, wherein a battery pack which may be removably attachable to a cordless power tool and to a charger may include at least one battery cell and a power limiting device. The power limiting device may be arranged in series with the at least one battery cell for limiting power output of the battery pack based on the component that is connected to the pack. Current and hence power out of the battery pack may be controlled as a function of total internal impedance in the battery pack, which may be adjusted depending on the component that is connected to the pack.

<CIT> describes a motor-driven appliance including a battery; a motor including permanent magnets as field magnets; a momentary maximum current upper limit storage unit in which a predetermined momentary maximum current upper limit is stored; a current detection unit that detects a current flowing in the motor; a current threshold setting unit that generates a current threshold based on the momentary maximum current upper limit, and outputs the generated current threshold; a current exceedance determination unit that determines whether the current detected by the current detection unit has become equal to or greater than the current threshold, and outputs an interruption signal used to interrupt a current path from the battery to the motor when the detected current has become equal to or greater than the current threshold; and a current flow interruption unit that interrupts the current path when the interruption signal is outputted from the current exceedance determination unit.

<CIT> describes that when a battery pack having an output voltage of <NUM> V that is connectable to an electric tool in a sliding manner is used as a power supply source for the electric tool that is connectable to a battery pack in an insertion manner and has a rated voltage of <NUM> V, the electric tool and the battery pack are connected to each other with an adaptor interposed therebetween. The adaptor has an FET that is switched at a predetermined duty of a predetermined frequency. The battery pack and the electric tool are connected or disconnected to or from each other by the switching operation, thereby dropping the output voltage of the battery pack. The voltage from the battery pack is detected. When the detected voltage is out of a predetermined value range, it is judged that the overcurrent or overdischarge has occurred. Then, the FET is turned off to stop the electric tool.

<CIT> describes a power tool system including: a secondary battery; a capacitor configured to supply a power to a motor; and a transforming unit configured to boost a battery voltage of the secondary battery to a charging voltage, the capacitor being charged with the charging voltage.

The invention is defined by the independent claims, while preferred embodiments form the subject of the dependent claims.

It is an object of the present disclosure to provide a battery unit and an electric tool system which are configured to reduce the probability of occurrence of failure in an electric tool body.

A battery unit according to the present disclosure includes a battery pack. The battery pack accommodates a battery. The battery pack is attachable to the electric tool body. The battery pack includes an output controller. The output controller is configured to control an output of the battery to the electric tool body in accordance with a condition.

An electric tool system according to one aspect of the present disclosure includes the battery unit and the electric tool body.

A battery unit and an electric tool system according to embodiments will be described below with reference to the drawings. Note that the embodiments below are mere examples of various embodiments of the present disclosure. Various modifications may be made to the following embodiments depending on design and the like as long as the object of the present disclosure is achieved. Moreover, figures described in the following embodiments are schematic views, and therefore, the ratio of sizes and the ratio of thicknesses of components in the drawings do not necessarily reflect actual dimensional ratios.

As illustrated in <FIG> and <FIG>, an electric tool system <NUM> of the present embodiment includes a battery unit <NUM> and an electric tool body <NUM>. The battery unit <NUM> includes a battery pack <NUM>. The battery unit <NUM> further includes a charger <NUM>.

The battery pack <NUM> includes a plurality of (four) batteries <NUM> (only one of which is shown in <FIG>). The battery pack <NUM> accommodates a plurality of batteries <NUM>. Specifically, the battery pack <NUM> includes a battery pack body <NUM> having a box shape. The plurality of batteries <NUM> are accommodated in the battery pack body <NUM>. The plurality of batteries <NUM> are secondary batteries. The plurality of batteries <NUM> are, for example, lithium ion batteries. The battery pack <NUM> is attachable to the electric tool body <NUM>. Specifically, the battery pack <NUM> is detachably attachable to the electric tool body <NUM>. The plurality of batteries <NUM> are connected in series to each other.

The plurality of batteries <NUM> supply electric power to the electric tool body <NUM>. The electric tool body <NUM> includes a motor <NUM>, a tool controller <NUM>, an inverter <NUM>, a detector <NUM>, a body <NUM>, and a chuck <NUM>. The chuck <NUM> is attached to the body <NUM>. To the chuck <NUM>, a bit such as a drill bit <NUM> or a driver bit is attachable. Moreover, the battery pack body <NUM> is detachably attachable to the body <NUM>. The tool controller <NUM> includes, for example, a microcontroller having a processor and memory. The processor executes a program stored in the memory, thereby realizing functions as the tool controller <NUM> in the present disclosure. The tool controller <NUM> controls operation of the motor <NUM>. The motor <NUM> operates based on electric power output from the plurality of batteries <NUM> and rotates the bit. The motor <NUM> is, for example, a brushless motor.

The battery pack <NUM> is connectable to the charger <NUM>. The charger <NUM> charges the plurality of batteries <NUM> (secondary batteries). The charger <NUM> has a plug and a cord. The plug is connectable to a socket which receives electric power from a commercial power supply. The charger <NUM> charges the plurality of batteries <NUM> by electric power supplied from the commercial power supply via the plug and the cord.

The battery pack <NUM> has storage <NUM>. The storage <NUM> is, for example, read only memory (ROM), random access memory (RAM), or electrically erasable programmable read only memory (EEPROM). The storage <NUM> stores pieces of information regarding item numbers of various types of electric tool bodies <NUM> different from each other in item number, ranges of voltage suppliable to the various types of electric tool bodies <NUM> different from each other in item number, and pieces of information associating the pieces of information regarding item numbers with the ranges of voltage. That is, the storage <NUM> stores the pieces of information regarding item numbers of the various types of electric tool bodies <NUM> and the ranges of voltage suppliable to the electric tool bodies <NUM> having the item numbers in association with each other. Note that it is required only that the storage <NUM> stores the item number of at least one type of electric tool body <NUM> and the range of voltage suppliable to the electric tool body <NUM> having the item number. The storage <NUM> does not necessarily have to store item numbers of a plurality of electric tool bodies <NUM> different from each other in item number.

The battery pack <NUM> acquires, from the electric tool body <NUM> to which the battery pack <NUM> is attached, information regarding the item number of the electric tool body <NUM>. The battery pack <NUM> then checks the item number with the plurality of item numbers stored in the storage <NUM>. Attaching the battery pack <NUM> to, for example, the electric tool body <NUM> triggers the battery pack <NUM> to acquire, from the electric tool body <NUM>, the information regarding the item number of the electric tool body <NUM>. If the same item number as the item number acquired has been stored in the storage <NUM>, the battery pack <NUM> determines, based on the pieces of information stored in the storage <NUM>, a range of voltage suppliable to the electric tool body <NUM> having the item number, and the battery pack <NUM> controls an output (a total output) of the plurality of batteries <NUM> such that a total voltage of the plurality of batteries <NUM> is within this range. This enables the battery pack <NUM> and the plurality of batteries <NUM> to be used in each of a plurality of electric tool bodies <NUM> different from each other in item number and in range of voltage that is suppliable to each electric tool body <NUM>.

Inputting, to the storage <NUM>, the information regarding the item number of the electric tool body <NUM> and the information representing the range of voltage suppliable to the electric tool body <NUM> enables the range of voltage suppliable to the electric tool body <NUM> to be set to an arbitrary range. The range of voltage suppliable to the electric tool body <NUM> is set based on, for example, specifications of the motor <NUM> and the inverter <NUM>. The information input to the storage <NUM> is provided, for example, from a physical server or a cloud server over a telecommunications network. Alternatively, the information input to the storage <NUM> is provided as information recorded on a non-transitory recording medium such as a memory card.

The battery pack <NUM> includes a conversion circuit <NUM>. The conversion circuit <NUM> is a DC-DC converter. The conversion circuit <NUM> performs DC-DC conversion of a direct-current voltage as an output voltage (a total output voltage) of the plurality of batteries <NUM> into a voltage within the range suppliable to the electric tool body <NUM>, and the conversion circuit <NUM> outputs the voltage to the electric tool body <NUM>. The inverter <NUM> of the electric tool body <NUM> converts the direct-current voltage output from the conversion circuit <NUM> into an alternating-current voltage (alternating-current power) and outputs the alternating-current voltage to the motor <NUM>.

The battery pack <NUM> includes an output controller <NUM>. The output controller <NUM> includes, for example, a microcontroller having a processor. The processor executes a program stored in the storage <NUM>, thereby realizing functions as the output controller <NUM> in the present disclosure. The conversion circuit <NUM> changes the magnitude of the output of the plurality of batteries <NUM> in accordance with the control performed by the output controller <NUM>. The output controller <NUM> controls the conversion circuit <NUM> to control the output (i.e., the output after voltage conversion by the conversion circuit <NUM>) of the plurality of batteries <NUM> to the electric tool body <NUM> in accordance with a condition. The condition includes a condition based on information regarding the electric tool body <NUM>. The output controller <NUM> acquires, from the storage <NUM>, the range of voltage suppliable to the electric tool body <NUM> as the information regarding the electric tool body <NUM>, and the output controller <NUM> controls the output of the plurality of batteries <NUM> so as to fulfill the condition that the voltage falls within the range. The range of voltage suppliable to the electric tool body <NUM> is defined, for example, by an upper limit value of the voltage suppliable to the electric tool body <NUM>. The upper limit value of the voltage suppliable to the electric tool body <NUM> is equal to, for example, a rated input voltage of the electric tool body <NUM>. The output controller <NUM> determines, in accordance with the information regarding the item number as the information regarding the electric tool body <NUM>, the upper limit value of the magnitude of the output voltage of the plurality of batteries <NUM>. The output controller <NUM> controls, by pulse width modulation (PWM) control performed on the conversion circuit <NUM>, the magnitude of the output voltage of the plurality of batteries <NUM> to be smaller than or equal to the upper limit value. For example, the conversion circuit <NUM> includes a switching element and a capacitor and turns on and off the switching element in accordance with the PWM signal from the output controller <NUM>, thereby controlling the pulse width of the output voltage of the switching element. The conversion circuit <NUM> causes the capacitor to convert (smooth) the output voltage of the switching element into a voltage having an amplitude according to the pulse width.

Moreover, the output controller <NUM> determines, in accordance with the information regarding the electric tool body <NUM>, the upper limit value of the magnitude of the output (specifically, the output voltage) of the plurality of batteries <NUM>, and a timing (hereinafter referred to as a start timing) to start controlling of reducing the magnitude of the output (specifically, the output voltage) of the plurality of batteries <NUM> when the magnitude of the output (specifically, the output voltage) of the plurality of batteries <NUM> exceeds the upper limit value. Determining the upper limit value of the magnitude of the output (the output voltage) of the plurality of batteries <NUM> by the output controller <NUM> is as described above. The start timing is stored in association with the item number in the storage <NUM>. In other words, the storage <NUM> stores pieces of information regarding item numbers of various types of electric tool bodies <NUM> and the start timings of the electric tool bodies <NUM> having the item numbers in association with each other. As the start timings, for example, timings determined in accordance with voltage resistance characteristics or anti-overcurrent characteristics of the various types of electric tool bodies <NUM> are stored in the storage <NUM>. The anti-overcurrent characteristic is, for example, a characteristic that a current which flows through the motor <NUM> and which has such-and-such an A (ampere) or higher has to be interrupted within such-and-such seconds. As the start timing, the storage <NUM> stores, for example, information saying such-and-such seconds after the magnitude of the output voltage of the plurality of batteries <NUM> exceeds the upper limit value. The output controller <NUM> determines the start timing by acquiring, from the storage <NUM>, a start timing corresponding to the item number of the electric tool body <NUM> to which the battery pack <NUM> is attached.

The battery pack <NUM> further includes an information acquirer <NUM>, a current value acquirer <NUM>, and a temperature sensor <NUM>.

The information acquirer <NUM> is configured to acquire, from the electric tool body <NUM>, information regarding the electric tool body <NUM>. Specifically, when the battery pack <NUM> is attached to the electric tool body <NUM>, the information acquirer <NUM> acquires, from the electric tool body <NUM>, information regarding the item number of electric tool body <NUM>.

In the electric tool body <NUM>, the detector <NUM> includes, for example, a shunt resistor. The detector <NUM> detects the magnitude of a current flowing through the motor <NUM>. The current value acquirer <NUM> acquires, from the detector <NUM>, a detection value of the magnitude of the current flowing through the motor <NUM> detected by the detector <NUM>. The output controller <NUM> controls the output of the plurality of batteries <NUM> to the electric tool body <NUM> in accordance with a condition based on the information regarding the electric tool body <NUM>. The information regarding the electric tool body <NUM> includes the detection value acquired by the current value acquirer <NUM>.

Specifically, when the detection value of the magnitude of the current flowing through the motor <NUM> exceeds the upper limit value, the output controller <NUM> controls the conversion circuit <NUM> such that the magnitude of an output current (a total output current) of the plurality of batteries <NUM> to the electric tool body <NUM> is less than or equal to the upper limit value. The output controller <NUM> controls the output voltage of the plurality of batteries <NUM> to control the output current of the plurality of batteries <NUM>. The upper limit value of the magnitude of the current flowing through the motor <NUM> is determined by the output controller <NUM> based on the upper limit value of voltage suppliable to the electric tool body <NUM>.

The temperature sensor <NUM> includes, for example, a thermistor. The temperature sensor <NUM> measures temperature of the plurality of batteries <NUM>. The output controller <NUM> acquires a measured value of the temperature of the plurality of batteries <NUM> measured by the temperature sensor <NUM>. The output controller <NUM> controls the output of the plurality of batteries <NUM> to the electric tool body <NUM> in accordance with a condition, wherein the condition includes a condition regarding the temperature of the plurality of batteries <NUM>. Specifically, the output controller <NUM> controls the output of the plurality of batteries <NUM> to the electric tool body <NUM> in accordance with the measured value of the temperature of the plurality of batteries <NUM>.

Specifically, when the measured value of the temperature of the plurality of batteries <NUM> exceeds a first temperature threshold, the output controller <NUM> controls the conversion circuit <NUM> such that the magnitude of the output current of the plurality of batteries <NUM> to the electric tool body <NUM> is reduced. Moreover, when the measured value of the temperature of the plurality of batteries <NUM> exceeds a second temperature threshold greater than the first temperature threshold, the output controller <NUM> controls the conversion circuit <NUM> such that output of the plurality of batteries <NUM> to the electric tool body <NUM> is stopped. Moreover, when the measured value of the temperature of the plurality of batteries <NUM> is smaller than a third temperature threshold lower than the first temperature threshold, the output controller <NUM> controls the conversion circuit <NUM> such that the magnitude of the output voltage of the plurality of batteries <NUM> to the electric tool body <NUM> is increased. Note that at this time, the output controller <NUM> controls such that the magnitude of the output voltage of the plurality of batteries <NUM> to the electric tool body <NUM> has a value smaller than or equal to an upper limit voltage suppliable to an electric tool body <NUM>.

Here, when the measured value of the temperature of the plurality of batteries <NUM> is smaller than the third temperature threshold, the output controller <NUM> may control the conversion circuit <NUM> such that the magnitude of the output voltage of the plurality of batteries <NUM> to the electric tool body <NUM> is reduced.

The electric tool body <NUM> is configured to select a value of a rated input voltage from a plurality of values. For example, the electric tool body <NUM> is configured to select the value of the rated input voltage from <NUM> V and <NUM> V. The electric tool body <NUM> is configured to select the value of the rated input voltage by an operation given to a button provided to electric tool body <NUM>. The value of the rated input voltage thus selected may be included in the information regarding the electric tool body <NUM>. That is, the output controller <NUM> may control the output of the plurality of batteries <NUM> to the electric tool body <NUM> based on the value of the rated input voltage thus selected.

According to the battery unit <NUM> of the present embodiment, the output controller <NUM> of the battery pack <NUM> controls the output of the plurality of batteries <NUM> to the electric tool body <NUM> in accordance with a condition. This enables the possibility of occurrence of failure in the electric tool body <NUM> to be reduced.

The output controller <NUM> controls the output of the plurality of batteries <NUM> specifically such that the output of the plurality of batteries <NUM> to the electric tool body <NUM> is less than or equal to the upper limit value of the voltage suppliable to the electric tool body <NUM>. The output controller <NUM> controls the output voltage of the plurality of batteries <NUM> to control the output current of the plurality of batteries <NUM>. Accordingly, when the battery pack <NUM> is replaced with a battery pack having another item number and having a different output voltage and a different output current, there is no need to replace the electric tool body <NUM> with an electric tool body of another item number, and therefore, the identical electric tool body <NUM> can continuously be used. For example, between a plurality of batteries which have the same cell voltages and different values of internal resistances, output voltages are different from each other, and output currents are different from each other. However, in the battery unit <NUM>, it is possible to use batteries including any of the plurality of batteries.

Variations of the first embodiment will be described below. The variations described below may be accordingly combined with each other.

In the first embodiment, it is described that the motor <NUM> in the electric tool body <NUM> is a brushless motor. However, the motor <NUM> may be a brush motor.

The information acquirer <NUM> may acquire information regarding the type of the motor <NUM> of the electric tool body <NUM> and information regarding a control method of the motor <NUM>. The information regarding the type of the motor <NUM> includes, for example, information regarding whether the motor <NUM> is a brush motor or brushless motor. The information regarding the control method of the motor <NUM> is, for example, whether or not a sensing result of a location of a rotor of the motor <NUM> is adopted, whether or not the inverter <NUM> is controlled, or whether or not the magnitude of the torque of the motor <NUM> is controlled. The output controller <NUM> may control the output of the plurality of batteries <NUM> to the electric tool body <NUM> in accordance with a condition based on pieces of information acquired by the information acquirer <NUM>.

Moreover, the output controller <NUM> may calculate the range of voltage suppliable to the electric tool body <NUM> by, for example, applying the information acquired by the information acquirer <NUM> to the condition expression. As described above, when the information acquirer <NUM> acquires the information regarding the type of the motor <NUM> of the electric tool body <NUM>, the information regarding the control method of the motor <NUM>, and the like, the output controller <NUM> can calculate the range of voltage suppliable to the electric tool body <NUM>.

The information regarding the electric tool body <NUM> may include information regarding the type of the electric tool body <NUM>. The output controller <NUM> may control the output from the plurality of batteries <NUM> to the electric tool body <NUM> in accordance with a condition based on the information regarding the type of the electric tool body <NUM>. The information regarding the type of the electric tool body <NUM> is, for example, the item number, model number, product number, serial number, product name, manufacturing date, or manufacturer's name of the electric tool body <NUM>. The information which the information acquirer <NUM> acquires and which relates to the electric tool body <NUM> may be manually input by a user to an input device included in the battery unit <NUM>. Specifically, information regarding the item number or the like of the electric tool body <NUM> may be manually input to the input device.

Moreover, the information acquirer <NUM> may acquire body information from the charger <NUM>. Specifically, a storage device included in the charger <NUM> stores a correspondence table representing the correspondence between the item number of the electric tool body <NUM> and the range of voltage suppliable to the electric tool body <NUM>. The information acquirer <NUM> may acquire the correspondence table from the storage device.

Moreover, when the output voltage of the plurality of batteries <NUM> decreases, the output controller <NUM> may reduce the output voltages from the conversion circuit <NUM>. Thus, when the output voltage of the plurality of batteries <NUM> decreases, the torque of the motor <NUM> of the electric tool body <NUM> decreases, but a prolonged period of use of the electric tool body <NUM> is possible. Moreover, in a case where a portable lighting fixture, instead of the electric tool body <NUM>, is attached to the battery pack <NUM>, the output controller <NUM> may reduce electric power supplied to the portable type lighting fixture when the output voltage of the plurality of batteries <NUM> decreases.

The storage <NUM> may store control contents of the conversion circuit <NUM> instead of the range of voltage suppliable to the electric tool body <NUM>. For example, the storage <NUM> may store, as a control content of the conversion circuit <NUM>, a duty ratio of a PWM signal output from the output controller <NUM> to the conversion circuit <NUM> when the output controller <NUM> performs PWM control of the output voltage of the conversion circuit <NUM>.

The output controller <NUM> of the first embodiment controls the output voltage of the plurality of batteries <NUM>. The control contents of the output controller <NUM> are not limited to this example, but the output controller <NUM> may control the output current or output power of the plurality of batteries <NUM>.

The output controller <NUM> of the first embodiment determines, in accordance with the information regarding the electric tool body <NUM>, the upper limit value of the magnitude of the output voltage of the plurality of batteries <NUM>, and a timing for starting control of reducing the magnitude of the output voltage of the plurality of batteries <NUM> when the magnitude of the output voltage of the plurality of batteries <NUM> exceeds the upper limit value. As described above, the output controller <NUM> of the first embodiment controls the output voltage of the plurality of batteries <NUM> in accordance with the output voltage of the plurality of batteries <NUM>. The output controller <NUM> is not limited to this example but may control the output current of the plurality of batteries <NUM> in accordance with the output current of the plurality of batteries <NUM>. Alternatively, the output controller <NUM> may control the output power of the plurality of batteries <NUM> in accordance with the output power of the plurality of batteries <NUM>. The output controller <NUM> may control at least one of the output voltage, output current, or output power of the plurality of batteries <NUM> in accordance with at least one of the output voltage, output current, or output power of the plurality of batteries <NUM>. Here, controlling at least one of the output voltage, output current, or output power of the plurality of batteries <NUM> includes controlling a timing for starting control of reducing the magnitude of at least one of the output voltage, output current, or output power of the plurality of batteries <NUM>. Moreover, controlling at least one of the output voltage, output current, or output power of the plurality of batteries <NUM> may include controlling the magnitude of at least one of the output voltage, output current, or output power of the plurality of batteries <NUM>.

The plurality of batteries <NUM> do not necessarily have to be included in the configuration of the battery pack <NUM>.

The plurality of batteries <NUM> are not limited to be connected in series but may be connected in parallel or series-parallel. Moreover, the plurality of batteries <NUM> may be primary batteries.

The first embodiment and the variations of the first embodiment described above disclose the following aspects.

The battery unit <NUM> includes the battery pack <NUM>. The battery pack <NUM> accommodates the battery <NUM>. The battery pack <NUM> is attachable to the electric tool body <NUM>. The battery pack <NUM> includes an output controller <NUM>. The output controller <NUM> is configured to control an output of the battery <NUM> to the electric tool body <NUM> in accordance with a condition.

With this configuration, the output controller <NUM> controls an output of the battery <NUM> to the electric tool body <NUM> in accordance with the condition. This enables the possibility of occurrence of failure in the electric tool body <NUM> to be reduced.

Moreover, in the battery unit <NUM>, the condition includes a condition based on information regarding the electric tool body <NUM>.

The configuration described above enables the output controller <NUM> to control the output of the battery <NUM> to the electric tool body <NUM> in accordance with the information regarding the electric tool body <NUM>.

Moreover, in the battery unit <NUM>, the battery pack <NUM> further includes the information acquirer <NUM>. The information acquirer <NUM> is configured to acquire, from the electric tool body <NUM>, the information regarding the electric tool body <NUM>.

With this configuration, the information acquirer <NUM> acquires, from the electric tool body <NUM>, the information regarding the electric tool body <NUM>. Therefore, there is no need to provide an additional component for providing the information regarding the electric tool body <NUM> to the information acquirer <NUM>.

Moreover, in the battery unit <NUM>, the output controller <NUM> is configured to determine, in accordance with the information regarding the electric tool body <NUM>, at least one of: the upper limit value of the magnitude of the output of the battery <NUM>; or a timing for starting control of reducing the magnitude of the output of the battery <NUM> when the magnitude of an output of the battery <NUM> exceeds the upper limit value.

With this configuration, it is possible to reduce excessive output from the battery <NUM> to the electric tool body <NUM>.

Moreover, in the battery unit <NUM>, the output controller <NUM> is configured to determine, as the upper limit value of the magnitude of the output of the battery <NUM>, an upper limit value of a magnitude of an output voltage of the battery <NUM> in accordance with the information regarding the electric tool body <NUM>.

With this configuration, it is possible to reduce application of an excessive voltage from the battery <NUM> to the electric tool body <NUM>.

Moreover, in the battery unit <NUM>, the output controller <NUM> is configured to perform PWM control such that the magnitude of the output voltage of the battery <NUM> is lower than or equal to the upper limit value.

This configuration enables the output controller <NUM> to continuously change the magnitude of the output voltage of the battery <NUM>.

Moreover, in the battery unit <NUM>, the battery pack <NUM> further includes the current value acquirer <NUM>. The current value acquirer <NUM> is configured to acquire a detection value of a current flowing through the motor <NUM> included in the electric tool body <NUM>. The information regarding the electric tool body <NUM> includes the detection value of the current flowing through the motor <NUM>.

This configuration enables the output controller <NUM> to control the output of the battery <NUM> to the electric tool body <NUM> in accordance with the value of a current flowing through the motor <NUM>.

Moreover, in the battery unit <NUM>, the information regarding the electric tool body <NUM> includes information regarding the type of the electric tool body <NUM>. With this configuration, it is possible to control the output of the battery <NUM> to the electric tool body <NUM> in accordance with the type of the electric tool body <NUM>. Moreover, in the battery unit <NUM>, the information regarding the electric tool body <NUM> includes information representing a range of voltage suppliable to the electric tool body <NUM>. With this configuration, it is possible to reduce the possibility of application of an overvoltage to the electric tool body <NUM>. Moreover, in the battery unit <NUM>, the condition includes the temperature of the battery <NUM>.

With this configuration, it is possible to control the output of the battery <NUM> to the electric tool body <NUM> in accordance with the temperature of the battery <NUM>.

The battery unit <NUM> further includes a charger <NUM>. The battery pack <NUM> is connectable to the charger <NUM>. The charger <NUM> is configured to charge a secondary battery serving as the battery <NUM>.

This configuration enables the battery <NUM> to be repetitively used by being charged.

Moreover, the electric tool system <NUM> includes the battery unit <NUM> and the electric tool body <NUM>.

A battery unit 2A and an electric tool system 1A according to a second embodiment will be described below with reference to <FIG> and <FIG>. Components similar to those in the first embodiment are denoted by the same reference signs, and the description thereof will be omitted.

The battery unit 2A further includes an adapter <NUM>. A conversion circuit <NUM> is included in the adapter <NUM> but not in a battery pack 3A. The adapter <NUM> is separable from the battery pack 3A. The conversion circuit <NUM> is thus separable from the battery pack 3A.

The adapter <NUM> is connectable to an electric tool body <NUM> and the battery pack 3A. The adapter <NUM> is used when an output voltage of a plurality of batteries <NUM> is outside a range of voltage suppliable to the electric tool body <NUM>.

The battery pack 3A outputs a direct-current voltage as the output voltage from the plurality of batteries <NUM> to the adapter <NUM>. The conversion circuit <NUM> of the adapter <NUM> performs DC-DC conversion of a direct-current voltage into a voltage within the range suppliable to the electric tool body <NUM>, and the conversion circuit <NUM> outputs the voltage to the electric tool body <NUM>.

Based on the second embodiment described above, the following aspects are disclosed.

The battery unit 2A according to the present embodiment includes the conversion circuit <NUM>. The conversion circuit <NUM> is configured to change the magnitude of an output of the battery <NUM> in accordance with the control performed by the output controller <NUM>. The conversion circuit <NUM> is separable from the battery pack 3A.

With this configuration, using the conversion circuit <NUM> and the battery pack 3A together is possible, or alternatively, using the battery pack 3A without using the conversion circuit <NUM> is possible.

Claim 1:
A battery unit (<NUM>), comprising:
a battery pack (<NUM>) accommodating a battery (<NUM>) and attachable to an electric tool body (<NUM>);
the battery pack (<NUM>) including an output controller (<NUM>) configured to control an output of the battery (<NUM>) to the electric tool body (<NUM>) in accordance with a condition,
wherein the condition includes a condition based on information regarding the electric tool body (<NUM>),
characterised in that
the output controller (<NUM>) is configured to determine, in accordance with the information regarding the electric tool body (<NUM>), a timing for starting control of reducing a magnitude of the output of the battery (<NUM>) when the magnitude of the output of the battery (<NUM>) exceeds an upper limit value of the magnitude of the output of the battery (<NUM>).