Patent ID: 12224407

DESCRIPTION OF THE EMBODIMENTS

In the following, the embodiments of a battery pack, a power tool and a system including the battery pack, the power tool, and an external device will be described in detail with reference to the drawings. Identical or equivalent forming elements, members, etc., in the respective drawings are labeled with identical symbols, and repeated descriptions will be omitted as appropriate. In addition, the embodiments do not serve to limit the invention, but should serve as exemplifications, and all the features and combinations thereof described in the embodiments are not limited as being necessarily essential to the invention.

FIG.1is a schematic perspective view illustrating a configuration example of a system (referred to in the following as “wireless linking system”)1000including a battery pack, a power tool, and an external device in the embodiment. As shown inFIG.1, the wireless linking system1000is configured so that a dust collector1, as an example of the external device, is connected to a circular saw2, as an example of the power tool, by a dust collecting hose4, and chips, etc., generated by the circular saw2can be sucked by the dust collector1. The head part of the dust collector1is removably fixed to the upper part of a tank part by a clamp mechanism5that serves as an installation mechanism.

The dust collector1and the circular saw2are connected by a power cable3, and the circular saw2can be supplied with power from the dust collector1. In addition, in the circular saw2, a battery pack6is disposed so as to be operable even in the case where no power is supplied from from the power cable3. In the following, while the power tool is exemplified as a circular saw, various other power tools, such as a jigsaw, a grinder, and a hammer drill, etc., can also be used. Firstly, descriptions are made about the dust collector1.

FIG.2is a schematic diagram of a circuit configuration of a dust collector (AC dust collector) as an example of the external device. As shown inFIG.2, the AC dust collector includes an alternating current (AC) power source201, a main switch202for supplying AC power obtained from the AC power source201to a motor204, a power circuit203which converts the AC power supplied from the AC power source201into direct current (DC) power which the respective units of an operation panel206, a display panel207, a wireless communication unit208, and a control unit209can use and outputs the DC power, and a switch205for controlling driving of the motor204according to a command signal from the operation panel206.

In addition, the dust collector1includes the operation panel206that receives an operation with respect to the dust collector1from the user, the display panel207that displays an operation state of the dust collector1receiving the operation received via the operation panel206, the wireless communication unit208that communicates wirelessly between the dust collector1and the battery pack6, and the control unit209that controls the respective units of the dust collector1.

The operation panel206includes a communication mode switch206athat switches ON/OFF of the wireless communication performed by the wireless communication unit208and a strength switch206bthat switches the setting of the strength of the driving force of the motor204or between single acting/linked acting. Single acting refers to a mode in which the dust collector1operates alone without linking with the battery pack6, and linked acting refers to a mode in which a linked operation where the dust collector1and the battery pack6are linked is performed.

The display panel207is a panel that displays information relating to the communication state (non-communication, attempting to connect, communication established), the driving state, the operation mode of the dust collector1, such as the communication state, the strength of the motor rotation speed, and the single acting/linked acting which the control unit209sets by receiving presses on the respective switches of the operation panel206. For example, the control unit209displays a green lamp indicating that the communication is established in a favorable communication state on the display panel207in the case where the communication speed is at or above a certain level, and displays a red lamp indicating that the communication state is not favorable on the display panel207in the case where the communication speed is below the level. In addition, for example, the control unit209displays “strong” indicating that the output of the motor is high on the display panel207in the case where the rotation speed of the motor204is equal to or higher than a predetermined threshold, and displays “weak” indicating that the output of the motor is low on the display panel207in the case where the rotation speed of the motor204is lower than the predetermined threshold. Moreover, for example, the control unit209displays the operation mode (single acting/linked acting) operated at the strength switch206b.

The wireless communication unit208is a unit that transmits or receives predetermined information to/from the battery pack installed to the power tool according to a wireless communication standard, such as Wi-Fi (registered trademark) communication or Bluetooth (registered trademark) communication. The wireless communication unit208is, for example, configured as a circuit unit including a chip on which a communication module for performing wireless communication according to the above standard is mounted and an antenna for transmitting and receiving radio waves within a frequency band defined by the above standard.

The control unit209is a unit for controlling the respective units of the dust collector1. The control unit209performs control over the motor204in correspondence with whether a linking signal is received from the battery pack installed to the power tool. In addition, in the case where the strength switch206bis operated to be set to a linked mode, the control unit209performs processes such as attempting, connecting, disconnecting the wireless communication with the battery pack6. The specific processes performed by the control unit209will be described in the following.

WhileFIG.2describes a dust connector supplied with power from an AC power source, as shown inFIG.3, it can also be configured that a dust collector1′ receives power supply from a DC power source such as a battery included in the dust collector1.

FIG.3is a schematic diagram of a circuit configuration of the dust collector (DC dust collector) as an example of the external device. As shown inFIG.3, the DC dust collector includes a direct current (DC) power source301configured by a battery cell, etc., a main switch302for supplying the DC power obtained from the DC power source301to a motor304, a power circuit303that outputs the DC power supplied from the DC power source301to the respective units of an operation panel306, a display panel307, a wireless communication unit308, and a control unit309, and a switch305for controlling the driving of the motor304according to a command signal from the operation panel306. Since the configurations of the respective units of the operation panel306, the display panel307, the wireless communication unit308, and the control unit309are the same as the AC dust collector shown inFIG.2, the descriptions in this regard will be omitted here. In reality, various detection circuits that detect the voltages, temperatures, currents, etc., of the battery cells forming the DC power source301, a protection circuit that protects over-charge, over-discharge, over-current with respect to the battery cells, and a control circuit that controls the discharge are disposed.

FIG.4is a schematic diagram of a connection circuit configuration of the battery pack6and a circular saw2a(without a micro controller unit (MCU)) as an example of the power tool. As shown inFIG.4, the circular saw2awithout the MCU has a tool side positive terminal401, a main switch402for supplying power supplied from the battery pack6to a motor404, a tool side trigger detection terminal403for detecting the power being supplied from the battery pack6, the motor404for driving the circular saw2awithout MCU, a switching element405for switching between passing and blocking of a charge current from the tool side positive terminal401to a tool side negative terminal406, the tool side negative terminal406, and a tool side LD terminal407that outputs a voltage value of the power tool. The switching element405is, for example, a P-channel type field effect transistor (FET) or an insulated gate bipolor transistor (IGBT).

The battery pack6includes two cell units whose rated output voltage is 18V, and is a battery compatible with two types of voltages, i.e., 36V and 18V. As shown inFIG.4, the battery pack6includes an upper positive terminal (terminal for supplying power to the power tool)601afor connecting a first cell unit, which is one unit of the 18V cell units, and the tool side positive terminal401, a lower positive terminal601bfor connecting a second cell unit, which is the other cell unit of the 18V cell units, and the tool side positive terminal401, and a voltage detection circuit602for detecting the voltage applied to the positive terminals601. The voltage detection circuit602includes an upper positive voltage detection circuit602afor detecting the voltage applied to the upper positive terminal601aand a lower positive voltage detection circuit602bfor detecting the voltage applied to the lower positive terminal601b.

In addition, the battery pack6has a battery side trigger detection terminal603for connecting with the tool side trigger detection circuit403, a trigger detection circuit604for detecting the reception of the power being supplied from the power tool by the battery side trigger detection terminal603, a wireless communication unit605, which is a circuit for communication with the external device (e.g., the dust collector1) according to a wireless communication standard, such as Wi-Fi (registered trademark) communication or Bluetooth (registered trademark) communication, an upper negative terminal606afor connecting the first cell unit and the tool side negative unit406, and a lower negative terminal606bfor connecting the second cell unit and the tool side negative unit406. In addition, the battery pack6has a battery side LD terminal607that inputs the voltage value of the power tool and a device power detection circuit608for detecting the voltage value of the power tool by the battery side LD terminal607.

In addition, the battery pack6has a cell unit609a, which is the first cell unit connected to the upper positive terminal601a, and an upper row cell unit protection circuit610athat protects the cell unit609a. In the cell unit609a, a plurality of battery cells are connected in series. An over-charge detection circuit611aand an over-discharge detection circuit612aare connected to the upper row cell unit protection circuit610a.

In addition, the battery pack6has a cell unit609b, which is the second cell unit connected to the lower positive terminal601b, and a lower row cell unit protection circuit610bthat protects the cell unit609b. In the cell unit609b, a plurality of battery cells are connected in series. An over-charge detection circuit611band an over-discharge detection circuit612bare connected to the lower row cell unit protection circuit610b.

These protection circuits monitor the voltages of the respective battery cells and serve to prevent over-charge or over-discharge of any of the battery cells. Since the voltage of the battery cell increases when the battery cell is charged, when the charge continues, and the voltage of the battery cell reaches a threshold voltage (charge limit voltage) of full charge, a signal is output from the protection circuit. These protection circuits also output a signal in the case where the voltage of at least one of the battery cells drops to a threshold voltage (discharge limit voltage) that draws concerns of over-discharge. As an example, the protection circuit outputs a high signal in the case where the battery pack6is at a normal usage voltage that is neither overly discharged nor fully charged, and outputs a low signal, such as a setting voltage, in a state other than the normal state, such as the case of notifying of over-discharge or full charge.

A power circuit613is a circuit that generates operation voltages of the cell units based on the voltages of the first cell unit and the second cell unit and supplies the operation voltages to a charge/discharge control unit620.

A cell temperature detection circuit614includes a temperature detection element, such as a thermistor that is not shown herein, disposed in a vicinity of each of the battery cells that form the cell unit609aand the cell unit609b, detects the temperature of each battery cell, and transmits the temperature to the charge/discharge control unit620.

A current detection circuit615detects the current of the cell unit609bbased on the voltages on two ends of a resistor621(fixed resistance) in serial connection with the cell unit609b, and transmits the current to the charge/discharge control unit620.

A residual capacity switch616is a switch for the user to verify the residual capacity of the battery pack6. A communication switch617, as an example of an operated unit, is a switch allowing the user to verify the communication state of the battery pack6and controlling the communication (switching among non-communication, attempting to connect, communication established) between the battery pack6and the external device. It is not required to use one single communication switch617to perform the controls (switching among non-communication, attempting to connect, communication established) with the external device. It may also be that communication switches are disposed in correspondence with the respective controls.

A residual capacity display panel618is a panel for, in the case where the user presses the residual switch616, displaying the residual capacity of the battery pack6by the charge/discharge control unit620. For example, in the case where the residual capacity of the battery pack6is equal to or greater than a predetermined threshold, the charge/discharge control unit620displays a green lamp indicating that the residual capacity is sufficient on the residual capacity display panel618. In the case where the residual capacity of the battery pack6is less than the predetermined threshold, the charge/discharge control unit620displays a red lamp indicating that the residual capacity is low on the residual capacity display panel618.

A communication state display panel619is a panel for, in the case where the user presses the communication switch617, displaying a pairing state with the external device that communicates wirelessly, or displaying the communication state (non-communication, attempting to connect, communication established) of the wireless communication unit605by the charge/discharge control unit620. For example, the charge/discharge control unit620displays a green lamp indicating that the communication is established in a favorable communication state on the communication state display panel619in the case where the communication speed is at or above a certain level, and displays a red lamp indicating that the communication state is not favorable on the communication state display panel619in the case where the communication speed is below the level. In addition, for example, in the case where the pairing process is successfully carried out, the communication state display panel619displays a blue lamp for the successful pairing process, and, in the case where the paring process fails, the communication state display panel619displays a red lamp for the failed pairing process.

The charge/discharge control unit620is a circuit which includes a central processing unit (CPU) that outputs a driving signal based on a program and data, a read only memory (ROM) that stores the program and the data, a random access memory (RAM) that temporarily stores the data, and a timer, etc., and controls the operations of the respective units of the battery pack6.

InFIG.4, an example in which the circular saw2awithout the MCU, as an example of the power tool, is connected to the battery pack6is described. In the following, the connection circuit configurations of other examples of the power tool will be described.

FIG.5is a schematic diagram of a connection circuit configuration of a circular saw2bwith an MCU, as another example of the power tool, and the battery pack6. Except for a communication connection terminal622, the configuration of the battery pack6shown inFIG.5is the same as the configuration shown inFIG.4. Therefore, the same reference symbols will be used, and the same descriptions will be omitted. The communication connection terminal622is a connection terminal for the charge/discharge control unit620of the battery pack6to communicate with a control unit422of the circular saw2bwith the MCU to transmit and receive various control information.

As shown inFIG.5, the circular saw2bwith the MCU has a tool side positive terminal411, a main switch412for supplying power supplied from the battery pack6to a motor414, a tool side trigger detection terminal413for detecting the power being supplied from the battery pack6, the motor414for driving the circular saw2bwith the MCU, a switching element415for switching between passing and blocking of a charge current from the tool side positive terminal411to a tool side negative terminal416, the tool side negative terminal416, and a tool side LD terminal417that outputs a voltage value of the power tool. The switching element415, like the case ofFIG.4, is configured by a P-channel type FET or an IGBT, for example.

In addition, the circular saw2bwith the MCU has a battery voltage detection circuit418, a power circuit419, a trigger detection circuit420, a current detection circuit421, a control unit422, and a communication connection terminal423.

The battery voltage detection circuit418is a detection member for measuring the voltage of the battery pack6, and the output thereof is connected to an A/D converter of the control unit422. A digital value corresponding to the detected battery voltage is input from the A/D converter, and the control unit422compares the digital value with a predetermined value set in advance, and sets, in the case where the battery residual capacity is less than the predetermined value, i.e., at the time of the over-discharge state, the FET to a blocked state. That is, by setting the gate signal of the FET to LOW, the control unit422temporarily stops the rotation of the motor414to protect the battery pack6.

The power circuit419is a circuit for maintaining the power of the control unit422. The control unit422is started in the case where the main switch412is turned off in the state where the power of the control unit422is not turned on. By continuously transmitting the command of keeping the power from the control unit422to the power circuit419, even in the state where the main switch412is in the returned state, the power supply to the control unit422is maintained, and the control unit422continues operating.

The trigger detection circuit420is a circuit for detecting that the main switch412is turned off and outputting a signal indicating that the main switch412is turned off to the control unit422.

The current detection circuit421is a circuit that detects a current flowing in the circuit (current flowing in the motor414), and is connected to the A/D converter of the control unit422. A potential difference between the tool side negative terminal416connected to the negative terminal of the battery pack6and the tool side positive terminal on the upstream side of a discharge path with respect to the tool side negative terminal416in the discharge path (the voltages on two ends of the shunt resistance) is detected by the current detection circuit421, and a digital value corresponding to the current value detected by the current detection circuit421is input to the A/D converter of the control unit422. The control unit422compares the converted digital value and a predetermined threshold set in advance, and makes a determination of trigger-ON (switch-ON) if the potential difference is equal to or greater than the threshold and makes a determination of trigger-off (switch-off) if the potential difference is less than or equal to the threshold or is zero.

The control unit422is composed of a microcomputer, and controls the respective units of the circular saw2bhaving the MCU.

The communication connection terminal423is a connection terminal for the control unit422to communicate with the charge/discharge control unit620of the battery pack6to transmit and receive various control information.

FIG.6is a schematic diagram of a connection circuit configuration of a multi-volt (MV) circular saw2c, as yet another example of the power tool, and the battery pack6. The configuration of the battery pack6shown inFIG.6is the same as the configuration shown inFIG.5. Therefore, the same reference symbols will be used, and the same descriptions will be omitted.

As shown inFIG.6, the MV circular saw2chas a tool side positive terminal431afor connecting with an upper positive terminal601aof the battery pack6, a tool side multi-volt positive terminal431bfor connecting with a lower positive terminal601bof the battery pack6, a main switch432for supplying power supplied from the battery pack6to a motor434, a tool side trigger detection terminal433for detecting the power being supplied from the battery pack6, the motor434for driving the MV circular saw2c, a switching element435for switching between passing and blocking of a charge current from the tool side positive terminal431ato a tool side negative terminal436b, a tool side multi-volt negative terminal436afor connecting the tool side multi-volt positive terminal431sband the upper negative terminal606aof the battery pack6, the tool side negative terminal436bfor connecting with the lower negative terminal606bof the battery pack6, and a tool side LD terminal437that outputs the voltage value of the power tool. The switching element435, like the case ofFIG.5, is configured by a P-channel type FET or an IGBT, for example.

In addition, the MV circular saw2chas a battery voltage detection circuit438, a power circuit439, a trigger detection circuit440, a current detection circuit441, a control unit442, and a communication connection terminal443. The respective units are the same as the battery voltage detection circuit418, the power circuit419, the trigger detection circuit420, the current detection circuit421, the control unit422, and the communication connection terminal423shown inFIG.5, therefore, the descriptions thereof will be omitted.

Accordingly, in the wireless linking system100, various power tools are connected to the battery pack6. As shown in the following, the battery pack6of the embodiment can detect the connection states of the upper positive terminal601aand the lower positive terminal601b, as the connection terminals without depending on the circuit configuration on the power tool side.

FIG.7is a diagram of a connection circuit configuration of main units of the battery pack6in a state in which the power tool is not connected.

The upper positive voltage detection circuit602aincludes a switch701athat turns on/off the upper positive voltage detection circuit602aaccording to the command from the charge/discharge control unit620and a resistor702aand a resistor703afor detecting a voltage (upper positive voltage) applied to the upper positive terminal601aat the time when the switch701ais ON.

The lower positive voltage detection circuit602bincludes a switch701bthat turns on/off the lower positive voltage detection circuit602baccording to the command from the charge/discharge control unit620and a resistor702band a resistor703bfor detecting a voltage (lower positive voltage) applied to the lower positive terminal601bat the time when the switch701bis ON.

The trigger detection circuit604includes a switch704that is turned on at the time when the power tool is not connected, and a resistor705that detects a voltage (upper positive' voltage) applied to the upper positive terminal601aat the time when the switch704is ON.

InFIG.7, the charge/discharge control unit620can calculate a detected value of the upper positive voltage by using the following formula. Detected value of upper positive voltage=(detected value of upper positive' voltage)×(resistor702a+resistor703a)/resistor703a

In addition, the detected value of the upper positive' voltage can be calculated by using the following formula. In the following formula, the voltage of the upper cell unit is the voltage of the cell unit609a. Detected value of upper positive' voltage=(voltage of upper cell unit)×resistor703a/(resistor702a+resistor703a+resistor705)

From these formulae, the detected value of the upper positive voltage can be eventually calculated by using the following formula. Detected value of upper positive voltage=(voltage of upper cell unit)×(resistor702a+resistor703a)/(resistor702a+resistor703a+resistor705)

FIG.8is a diagram of a connection circuit configuration of the main units of the battery pack6in a state in which a power tool corresponding to 18V is connected. The configuration of the battery pack6shown inFIG.8is the same as the case ofFIG.7. Therefore, the same reference symbols will be used, and the same descriptions will be omitted. InFIG.8, the tool side positive terminal401(or the tool side positive terminal411) is respectively connected to the upper positive terminal601aand the lower positive terminal601bof the battery pack6, and the tool side negative terminal406(or the tool side negative terminal416) is respectively connected to the upper negative terminal606aand the lower negative terminal606bof the battery pack6.

InFIG.8, the charge/discharge control unit620can calculate a detected value of the upper positive voltage by using the following formula. That is, the detected value of the upper positive' voltage is calculated according to the following: Detected value of upper positive' voltage=(voltage of upper cell unit)×resistor703a/(resistor702a+resistor703a+resistor705). Here, when the resistor705is sufficiently smaller than the resistor703a(resistor705<<resistor703a), the above formula can be represented as follows: Detected value of upper positive' voltage≈(voltage of upper cell unit)×resistor703a/(resistor702a+resistor703a)

InFIG.8, since the upper cell unit and the lower cell unit are connected in parallel, a formula can be expressed in the following: Detected value of upper positive' voltage≈(voltage of lower cell unit)×resistor703a/(resistor702a+resistor703a). Therefore, eventually, the detected value of the upper positive voltage can be calculated by using the following formula: Detected value of upper positive voltage=(voltage of upper cell unit)=(voltage of lower cell unit)

FIG.9is a diagram of a connection circuit configuration of the main units of the battery pack6in a state in which a power tool corresponding to 36V is connected. The configuration of the battery pack6shown inFIG.8is the same as the case ofFIG.7. Therefore, the same reference symbols will be used, and the same descriptions will be omitted. InFIG.9, the tool side positive terminal431ais connected to the upper positive terminal601aof the battery pack6, and the tool side multi-volt positive terminal431bis connected to the lower positive terminal601bof the battery pack6. In addition, the tool side multi-volt negative terminal436ais connected to the upper negative terminal606aof the battery pack6, and the tool side negative terminal436bis connected to the lower negative terminal606bof the battery pack6. Accordingly, the cell unit609aand the cell unit609bare connected in series via the tool side multi-volt positive terminal431band the tool side multi-volt negative terminal436a.

InFIG.9, the charge/discharge control unit620can calculate a detected value of the upper positive voltage by using the following formula. That is, the detected value of the upper positive' voltage is calculated according to the following: Detected value of upper positive' voltage=(voltage of upper cell unit+voltage of lower cell unit)×resistor703a/(resistor702a+resistor703a). Therefore, eventually, the detected value of the upper positive voltage can be calculated by using the following formula: Detected value of upper positive voltage=(voltage of upper cell unit)+(voltage of lower cell unit)

Accordingly, in the embodiment, the charge/discharge control unit620of the battery pack6determines the type of the power tool connected to the battery pack6and whether a power tool is connected or not connected by calculating the voltage (upper positive voltage) applied to the upper positive terminal601a, without depending on the circuit configuration of the power tool side. That is, the charge/discharge control unit620detects three states, that is, a state in which a power tool is connected, a state in which a power tool not compatible with multi-volt is connected, and a state in which a power tool compatible with multi-volt is connected in correspondence with the value of the voltage (upper positive voltage) applied to the upper positive terminal601a. Specifically, from the respective formulae shown inFIGS.7to9, in the case where the detected value of the upper positive voltage is greater than or equal to the detected value of the lower positive voltage (FIGS.8and9), the charge/discharge control unit620determines that a power tool is connected, and in the case where the detected value of the upper positive voltage is less than the lower positive voltage (FIG.7), the charge/discharge control unit620determines the connection of the power tool as canceled.

Regarding the switch704and the resistor705, the setting as follows is preferred. Specifically, in the state in which a power tool is not connected, the upper positive voltage is not indefinite with respect to a reference potential A. In addition, when the switch704is turned on, a discharge path of the lower cell unit can be created during serial connection. Therefore, from the perspective of saving power or preventing the voltage imbalance between the voltages of the upper and lower cell units, it is preferred that the switch704is turned on only at the timing of detection, and in the case where the power tool in serial connection is detected, the frequency at which the switch704is turned on may be as low as possible.

FIG.10is a flowchart illustrating the processes of the battery pack6in the wireless linking system1000. The wireless communication unit605of the battery pack6attempts to communicate with the external device (e.g., the dust collector1) according to the command from the charge/discharge control unit620, and determines whether it is in a communication established state (S1001).

In the case where the wireless communication unit605determines that it is not in the communication established state with the external device (S1001: No), the wireless communication unit605determines whether the current communication state is a state of attempting for communication connection (S1002). For example, the wireless communication unit605determines that the current communication state is the state of attempting for communication connection in the case of within a predetermined time since the attempt for communication starts, or the wireless communication unit605determines that the current communication state is the state of attempting for communication connection in the case where the communication switch617is pressed, as a predetermined operation with respect to the battery pack6.

In the case where the wireless communication unit605determines that the current communication state is not the state of attempting for communication connection (S1002: No), the wireless communication unit605determines whether the communication switch617is pressed, as the predetermined operation with respect to the battery pack6, and whether a command signal for attempting for communication connection is received from the charge/discharge control unit620(S1003). In the case where the wireless communication unit605determines that the command signal for attempting for communication connection is received from the charge/discharge control unit620(S1003: Yes), the wireless communication unit605proceeds to the state of attempting for communication connection. Alternatively, in the case where the wireless communication unit605determines that the command signal for attempting for communication connection is not received from the charge/discharge control unit620(S1003: No), the flow returns to S1001without any action, and subsequent processes are repeated.

In S1002, in the case where the wireless communication unit605determines that the current communication state is the state of attempting for communication connection, the wireless communication unit605performs a connection attempt process (S1005). The connection attempt process is, for example, a process that performs a paring process with the external device that communicates wirelessly. It may also be that the wireless communication unit605proceeds to perform the connection attempt process in the case where the communication switch617is pressed, as the predetermined operation with respect to the battery pack6.

The wireless communication unit605determines whether a communication connection is established through the connection attempt process (S1006), and further determines whether a communication attempt is performed within a predetermined time (S1007) in the case where the communication connection is not established through the connection attempt process (S1006: No).

In the case where the wireless communication unit605determines that the communication attempt is performed within the predetermined time (S1007: Yes), the wireless communication unit605determines that the communication connection with the external device cannot be established and proceeds to a non-communication state (S1008). It may also be that the wireless communication unit605proceeds to the non-communication state in the case where the communication switch617is pressed, as the predetermined operation with respect to the battery pack6. Alternatively, in the case where the wireless communication unit605determines that the communication attempt is not performed within the predetermined time (S1007: No), the flow returns to S1001without any action, and subsequent processes are repeated.

In S1006, in the case where the wireless communication unit605determines that the communication connection is established through the connection attempt process (S1006:Yes), the wireless communication unit605proceeds to the communication established state (S1009). It may also be that the wireless communication unit605proceeds to the communication established state in the case where the communication switch617is pressed, as the predetermined operation with respect to the battery pack6.

In S1001, in the case where the wireless communication unit605determines that it is in the communication established state with the external device (S1001: Yes), the charge/discharge control unit620determines whether the voltage detection circuit602detects the voltage applied to the positive terminal601(or the current detection circuit615detects the current of the cell unit609b) (S1010). That is, the charge/discharge control unit620determines whether the voltage detected by the voltage detection circuit602satisfies the predetermined relation as shown inFIG.8orFIG.9.

In the case where the charge/discharge control unit620determines that the voltage detection circuit602detects the voltage applied to the positive terminal601(or the current detection circuit615detects the current of the cell unit609b) (S1010: Yes), the charge/discharge control unit transmits a linking signal (linking command) to the external device with which the communication connection is established in S1006(S1011). Alternatively, in the case where the charge/discharge control unit620determines that the voltage detection circuit602detects the voltage applied to the positive terminal601, and the current detection circuit615does not detect the current of the cell unit609b(S1010: No), the flow proceeds to S1012without any action.

The charge/discharge control unit620determines whether the communication switch617of the battery pack6is pressed in S1012and, in the case where the switch is pressed (S1012: Yes), the flow proceeds to S1014. Alternatively, in the case where the charge/discharge control unit620determines that the switch is not pressed (S1012: No), the charge/discharge control unit620determines whether the connection of the power tool is canceled (S1013). Whether the connection of the power tool is canceled may be determined by the charge/discharge control unit620according to whether the voltage detected by the voltage detection circuit602no longer satisfies the predetermined relation as shown inFIG.8orFIG.9, or whether the signal for detecting the reception of the power being supplied from the power tool is no longer received from the trigger detection circuit604. By performing such process, the cancellation of the connection of the power tool can be determined on the side of the battery pack6.

In the case where the charge/discharge control unit620determines that the communication switch617of the battery pack6is pressed (S1012: Yes), or in the case where the charge/discharge control unit620determines that the connection of the power tool is canceled (S1013: Yes), the charge/discharge control unit620transmits a wireless communication cancellation command for canceling the wireless communication with the external device in the communication established state to perform a communication connection cancellation process, and proceeds to a non-connection state (S1014). It may also be that the communication connection cancellation process is performed in the case where the communication switch617is pressed, as the predetermined operation with respect to the battery pack6. Alternatively, in the case where the charge/discharge control unit620determines that the connection of the power tool is not canceled (S1013: No), the flow returns to S1001, and the subsequent processes are repeated.

Accordingly, the charge/discharge control unit620of the battery pack6performs a first determination process (e.g., S1001, S1003ofFIG.10) that determines whether the wireless communication with the external device is established, and, in the case where the charge/discharge control unit620determines that the wireless communication with the external device is established, the charge/discharge control unit620performs a second determination process (e.g., S1010ofFIG.10) that determines whether the voltage detection circuit602detects the voltage applied to the positive terminal601and whether the current detection circuit615detects the current of the cell unit609b. In addition, in the case whether the first determination process and the second determination process are both satisfied, a linking signal (linking command) for a linked operation with the external device is transmitted to the external device. Therefore, the linking command can be transmitted reliably with respect to the external device capable of wireless communication. In addition, since the battery pack performs all the above processes, the compatibility with the external device can be maintained even if the external device is a power tool without a wireless communication function. In addition, as in S1013and S1013ofFIG.10, when the connection with the power tool is canceled, since the wireless communication with the external device is canceled, malfunctions of the external device due to a linked operation resulting from the battery pack side can be avoided.

FIG.11is a flowchart illustrating processes of the external device (e.g., the dust collector1) in the wireless linking system1000. In the following, while the case where the external device is the AC dust collector shown inFIG.2is described, the DC dust collector shown inFIG.3and other power tools can also be considered in a similar manner.

The wireless communication unit208of the dust collector1attempts to communicate with the battery pack6according to the command from the control unit209, and determines whether it is in the communication established state with the battery pack6(S1101).

In the case where the wireless communication unit208determines that it is not in the communication established state with the battery pack6(S1101: No), the wireless communication unit208determines whether the current communication state is a state of attempting for communication connection (S1102). For example, the wireless communication unit208determines that the current communication state is the state of attempting for communication connection in the case of within a predetermined time since the attempt for communication starts.

In the case where the wireless communication unit208determines that the current communication state is not the state of attempting for communication connection (S1102: No), the control unit209determines whether the strength switch206bof the operation panel206is operated to be set to the linked mode (S1103). In the case where the wireless communication unit208determines that the strength switch206bof the operation panel206is operated to be set to the linked mode (S1103: Yes), the control unit209proceeds to the state of attempting for communication connection. Alternatively, in the case where the wireless communication unit209determines that the strength switch206bof the operation panel206is not operated to be set to the linked mode (S1103: No), the flow returns to S1101without any action, and subsequent processes are repeated.

In S1102, in the case where the wireless communication unit208determines that the current communication state is the state of attempting for communication connection (S1102: Yes), the control unit209determines whether the linked mode is set (S1105), like the case of S1103.

In the case where the control unit209determines that the linked mode is set (S1105: Yes), the wireless communication unit208performs the connection attempt process (S1107). The connection attempt process is, for example, a process that performs a paring process with the battery pack6that communicates wirelessly. Alternatively, in the case where the linked mode is not set (S1105: No), the wireless communication unit208returns to S1101and repeats the subsequent processes after proceeding to the non-communication state.

The wireless communication unit208determines whether the communication connection is established through the connection attempt process (S1108), and returns to S1101without any action and repeats the subsequent processes in the case where the wireless communication unit208determines whether the communication connection is not established through the connection attempt process (S1108: No).

In S1108, in the case where the wireless communication unit208determines that the communication connection is established through the connection attempt process (S1108: Yes), the wireless communication unit208proceeds to the communication established state (S1109).

In S1101, in the case where the wireless communication unit208determines that it is in the communication established state with the battery pack6(S1101: Yes), the wireless communication unit208determines whether the linking signal (linking command) is received from the battery pack6(S1110). In the case where the wireless communication unit208determines that the linking signal (linking command) is received from the battery pack6(S1110: Yes), the control unit209turns on the motor204. Alternatively, in the case where the wireless communication unit208determines that the linking signal (linking command) is not received from the battery pack6(S1110: No), the control unit209determines whether the state in which the wireless communication unit208does not receive the linking signal (linking command) lasts a predetermined time (S1112).

In the case where the control unit209determines that the state in which the wireless communication unit208does not receive the linking signal (linking command) lasts the predetermined time (S1112: Yes), the motor204is turned off (S1113). Alternatively, in the case where the control unit209determines that the state in which the wireless communication unit208does not receive the linking signal (linking command) does not last the predetermined time (S1112: No), the flow proceed to S1114without any action.

The control unit209determines whether the linked mode is set in S1103or S1105(S1114), and, in the case where the control unit209determines that the linked mode is set (S1114: Yes), the flow returns to S1101without any action, and the subsequent processes are repeated.

Alternatively, in the case where the control unit209determines that the linked mode is not set (S1114: No), the control unit209performs the communication connection cancellation process for canceling the wireless communication with the external device in the communication established state and proceeds to the non-connection state (S1115).

Accordingly, the control unit209of the external device performs a third determination process (e.g., S1101ofFIG.11) that determines whether the wireless communication with the battery pack is established, and, in the case where the control unit209determines that the wireless communication is established, further determines whether the linking signal (linking command) is received from the battery pack6. In the case where the linking signal (linking command) is received, the control unit209turns on the motor204. Therefore, a linked operation can be reliably carried out with the battery pack6. In addition, the control unit209determines whether the linked mode is set in the state where the motor204is ON, and in the case where the linked mode is not set in the state, the control unit209cancels the wireless communication with the battery pack6. Therefore, malfunctions of the external device due to the linked operation resulting from an operation on the external device side can be prevented.

Also, while the embodiment is configured to, as the communication connection cancellation process, transmit the wireless communication cancellation command to the external device, the means for the communication connection cancellation process is not limited to the above. For example, it may also be a configuration where connection confirmation signals are transmitted and received between the battery pack and the external device in the wireless communication state and the wireless communication is canceled in the case where one of the battery pack and the external device does not receive the connection confirmation signal for a predetermined time, and that the communication connection cancellation process is set as a process of stopping transmitting the connection confirmation signal for the predetermined time or more. In addition, while the embodiment is configured as performing the communication connection cancellation process and proceeding to the non-connection state when the connection between the battery pack and the power tool is determined as canceled (S1013: Yes, S1014ofFIG.10), it may also be configured that the communication connection cancellation process is performed after a predetermined time after the connection between the battery pack and the power tool is determined as canceled. That is, instead of performing the communication connection cancellation process immediately after the connection between the battery pack and the power tool is canceled, the communication connection cancellation process may also be performed after the predetermined time. With such configuration, in the case where the connection of the power tool to the battery pack and the cancellation of the connection are to be consecutively performed repetitively for several times in a short time, it is not necessary to perform the processes ofFIG.10from the very beginning, and the operability can be facilitated. Therefore, such configuration is effective. For example, there is a case where the battery pack and the power tool have a contact failure between terminals due to chattering resulting from vibrations of the power tool, etc. Or, there is a case where the connected battery pack is temporarily removed and connected again to confirm whether the connected battery is the one to be used (confirming marks etc., on the connection surface with the power tool, etc.). In addition, even in the case where the connection between the battery pack and the power tool is not canceled (S1013: No inFIG.10), when one of the battery pack, the power tool and the dust collector is in a non-use state for a second predetermined time (e.g., several hours), the communication connection cancellation process may also be performed. With such configuration, the consumed power of the battery pack can be suppressed.