JP5313616B2 - Battery pack for electric tools and electric tools - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively reduce power consumption of a battery while reliably monitoring a battery condition during a period from immediately after the end of discharge to a power tool until the battery is stabilized. <P>SOLUTION: In a battery pack, after the end of discharge to a tool body (S220:NO), when the following respective conditions are all established, the battery pack is switched to a sleep mode (S280). The respective conditions are: a condition that a change amount dT/dt of a cell temperature is smaller than 5&deg;C and the temperature change is in a stable state (S240:YES); a condition that all battery cells constituting a battery are in a cell-voltage stable state in which a change amount dV/dt of the cell voltage of each battery cell becomes larger than -100 mV (S250:YES) and &le;0 (S260:YES); and a condition that the cell temperature is lower than 60&deg;C and the temperature is in a stable state (S270:YES). <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an electric power tool battery pack composed of a rechargeable secondary battery and an electric power tool that is mounted with the electric power tool battery pack and operates by receiving electric power supplied from the electric power tool battery pack.

  In a battery pack for an electric tool using a battery made of a lithium ion secondary battery (hereinafter also simply referred to as “battery pack”), the battery is being charged while the battery is being charged or discharged from the battery to the electric tool to which power is supplied. Therefore, a monitoring circuit that operates with a battery as a power source is usually provided. Examples of monitoring items by the monitoring circuit include the voltage of each battery cell constituting the battery, the temperature of each battery cell (or the temperature of the entire battery), and the charge / discharge current from the battery. The voltage of the entire battery based on the sum of the voltages of the battery cells is one of the monitoring items.

  Thus, when the battery pack is provided with a monitoring circuit that always operates, the monitoring circuit always consumes a small amount of battery power although the trace amount is small. For this reason, the remaining capacity of the battery gradually decreases without supplying power to the power tool, and the battery capacity becomes empty in a relatively short period of time.

  On the other hand, considering the purpose of the monitoring circuit, the battery is normally in a stable state when the battery is not being charged or discharged to the power tool. There is no need to monitor. Therefore, conventionally, a technique is known in which the battery pack is switched to the sleep mode to stop the operation of the monitoring circuit when the battery is not used.

Various timings for switching to the sleep mode have been proposed. For example, in Patent Document 1, when the load is cut off from the storage battery, the supply of power supply energy to the circuit in the storage battery is stopped immediately after that or at a time shift. Is disclosed. Further, for example, Patent Document 2 discloses that power supply to the control unit in the battery pack is stopped after a predetermined time has elapsed since the operation of the trigger switch of the electric power tool was released.
JP 2003-264008 A JP 2006-280043 A

  By the way, during the discharge in which the battery is discharged, such as when the electric tool is used, the battery voltage decreases and the battery temperature increases due to the discharge current and the internal resistance in the battery. When the discharge is completed, the battery voltage rises and recovers to the original open-circuit voltage value, and the battery temperature also decreases and recovers to the vicinity of the ambient temperature, so that the battery becomes stable.

  However, due to the characteristics of the battery, the battery voltage that has dropped during discharge and the battery temperature that has risen do not recover immediately after the end of discharging, but require some time to recover. In other words, the battery gradually recovers from the state immediately after the end of discharge, and conversely, the battery cannot be said to be in a chemically stable state during the gradually recovering period. In this unstable state, the battery may be abnormal for some reason.

  As an abnormality of the battery that occurs in an unstable state immediately after the end of discharge, for example, a light short circuit of a battery cell constituting the battery can be cited. This light short is a phenomenon in which the electrodes inside the cell are short-circuited for some reason.

  In this light short-circuit, even if the electrodes are short-circuited inside the cell, the short-circuit portion is immediately melted by the short-circuit current (that is, a short-circuit that occurs instantaneously). For this reason, a battery that has caused a light short circuit is apparently normal. However, even though it is a short-circuit that occurs instantaneously, it does not change that an abnormality has occurred inside the cell, so it is necessary to take measures such as detecting the occurrence of a light short-circuit and then disabling the battery. is there.

  However, if the battery pack is switched to the sleep mode immediately after the end of discharging to stop the operation of the monitoring circuit in order to reduce the power consumption of the battery, an abnormality such as a light short circuit occurs immediately after the end of discharging as described above. Since the monitoring circuit does not operate in spite of the unstable state that is likely to occur for a while, it is naturally impossible to detect the abnormality such as the light short circuit described above.

  On the other hand, instead of switching to sleep mode immediately after the end of discharge, as described in the above-mentioned patent document, if the switch is made to sleep mode when a predetermined time has elapsed after the end of discharge, monitoring is performed until the battery becomes stable. It is possible to operate the circuit once.

  However, since the time required for the battery to be stabilized immediately after the end of discharge greatly depends on the current and temperature during discharge, the degree of deterioration of the cells, and the like, it is extremely difficult to accurately obtain this time. For this reason, for example, assuming the case where it takes the longest time for the battery to stabilize, even if such a case occurs, it takes a relatively long time to ensure that the monitoring circuit operates until the battery becomes stable Must be set.

  However, if the time from immediately after the end of discharge to the switch to the sleep mode is set to a long time in advance, it is naturally assumed that the battery is in a stable state before the set time elapses. (Rather often). For this reason, it is difficult to effectively reduce the power consumption of the battery.

  This problem is not limited to battery packs that use lithium ion secondary batteries, but may also occur in various battery packs that include a monitoring circuit that monitors the state of the battery.

  The present invention has been made in view of the above problems, and can effectively reduce the power consumption of the battery while reliably monitoring the state of the battery immediately after the discharge to the power tool is completed and until the battery is stabilized. It is an object of the present invention to provide a battery pack for a power tool that can be used, and a power tool that operates using the battery pack.

  The battery pack for an electric tool of the present invention made to solve the above-described problem operates with a battery having at least one battery cell and power supplied from the battery, and detects at least a discharge current from the battery. A monitoring circuit that has a discharge current detection unit, a cell voltage detection unit that detects a voltage of the battery cell, and a temperature detection unit that detects a temperature of the battery, and monitors a state of the battery based on a detection result by each detection unit; The monitoring circuit detects that the discharge current has reached a discharge end state that is equal to or less than a predetermined current value. The monitoring circuit further determines the amount of change in the voltage of the battery cell. Voltage stable state within the stable voltage change amount range, or stable temperature state where the battery temperature change amount is within the predetermined temperature change stable range Sleep mode switching means for switching the battery pack for the electric tool to the sleep mode by stopping at least a part or all of the operation of the monitoring circuit when it is detected that at least one of them is detected. It is characterized by.

  In the battery back configured in this way, for example, when the power supply from the battery to the power supply target such as a power tool (that is, discharge from the battery) is finished and the discharge is finished, the sleep state is immediately switched to. Instead, when it is detected that the battery is in a predetermined stable state (at least one of the voltage stable state and the temperature stable state), the battery is switched to the sleep state.

  Therefore, after the discharge is completed, the monitoring by the monitoring circuit is continued at least until the battery is stabilized, and this can be reliably detected when an abnormality such as a light short circuit of the cell described above occurs. On the other hand, when the battery becomes stable, the sleep mode switching means switches to the sleep mode, and the monitoring circuit stops part or all of the operation.

  Therefore, according to the battery pack for an electric tool of the present invention, the power consumption of the battery is effectively reduced while reliably monitoring the state of the battery after the discharge to the electric tool is completed and until the battery is stabilized. can do.

  Here, the monitoring circuit may detect the voltage stable state when the voltage change amount is within the voltage change amount stable range for all the battery cells included in the battery. According to the power tool battery pack configured as described above, it is possible to more reliably detect battery abnormality.

  The sleep mode switching means switches to the sleep mode when the discharge end state is detected by the monitoring circuit and when both the voltage stable state and the temperature stable state are further detected by the monitoring circuit. There should be.

  In this way, after the end of the discharge, when both the voltage of the battery cell and the temperature of the battery are stabilized, that is, when the battery is reliably stabilized, the switching to the sleep mode is performed. Monitoring of the battery after completion can be performed sufficiently.

  The sleep mode switching means is a case in which the discharge end state is detected by the monitoring circuit, and further the voltage threshold value and the temperature stable state are both detected by the monitoring circuit and the battery temperature is predetermined. It is preferable to switch to the sleep mode when lower is detected.

  That is, even if the change amount of the battery temperature is within the temperature change amount stable range, if the temperature itself is still high, some abnormality may occur in the battery. Therefore, it is possible to detect whether the temperature is stable not only for the amount of change but also for the value itself, that is, whether it is lower than the temperature threshold, and if it is lower than the temperature threshold, switching to the sleep mode will result in discharge. Monitoring of the battery after completion can be performed with higher accuracy.

  On the other hand, when the monitoring circuit detects at least one of the change in the voltage of the battery cell outside the voltage change amount stable range or the change in the battery temperature outside the temperature change stable range. It may be determined that the battery is in an abnormal state.

  It should be noted that various actions can be taken when it is determined that an abnormal state has occurred. For example, the fact that the abnormal state has occurred may be recorded, an external notification may be made, or a battery back You may make it set so that itself cannot be used hereafter.

  In addition, when a predetermined mode return condition is satisfied in the power tool battery pack after the sleep mode switching means is switched to the sleep mode, the mode return means sleeps the power tool battery pack. It is preferable to restore the normal operation state from the mode.

  In this case, various mode return conditions are conceivable. For example, the mode return means has a discharge start detection means for detecting the start of discharge from the battery, and the discharge start detection means starts discharge. When it is detected, it may be determined that the mode return condition is satisfied. In this way, when the discharge is started again after switching to the sleep mode, the monitoring operation by the monitoring circuit can be reliably restarted.

  And the battery pack for electric tools which has a discharge start detection means in this way can be comprised as follows more specifically. That is, the discharge current detection means includes a signal acquisition means for acquiring an electrical signal corresponding to the magnitude of the discharge current, and a signal for amplifying the electrical signal acquired by the signal acquisition means with a predetermined first gain. And amplifying means, and the operation is continued even after switching to the sleep mode by the sleep mode switching means. The discharge start detecting means is configured to detect that the discharge has started based on the electric signal amplified by the signal amplifying means. In addition, gain switching means for switching the gain of the signal amplifying means to a second gain larger than the first gain when the monitoring circuit detects a discharge end state is provided.

  In the battery pack for an electric power tool configured as described above, when discharging from the battery to the power supply target is performed, the gain of the signal amplifying unit is set to the first gain, so that the discharging is in progress. While the discharge current can be reliably detected, the second gain larger than the first gain is set after the end of the discharge, and a small discharge current is amplified to a large value. Therefore, when the discharge is started again, the discharge start detecting means can reliably detect this even if the discharge current is small, and can quickly return the battery pack from the sleep mode.

  When the gain switching unit is configured to switch the gain of the signal amplifying unit to the second gain when the discharge end state is thus established, the gain switching unit is configured to start the discharge by the discharge start detecting unit. When detected, the gain may be switched to the first gain again.

  Thus, by switching the gain to the first gain again at the start of discharge (decreasing the gain), the discharge current can be reliably monitored both at the end of discharge and during discharge.

  In addition, the battery pack for electric power tool operates in the sleep mode and determines whether or not the battery voltage has become lower than a predetermined voltage lower threshold, and when in a normal operation state When the battery voltage determining means determines that the battery voltage has become lower than the voltage lower limit threshold, the shutdown mode switching means switches the battery pack to a shutdown mode in which the battery power consumption is lower than in the sleep mode. When the battery voltage determining means determines that the battery voltage has become lower than the voltage lower limit threshold, the mode return means determines that the mode return condition is satisfied. Also good.

  For example, if the battery pack is left unused for a long period of time after switching to the sleep mode, the capacity of the battery gradually decreases due to the natural discharge of the monitoring circuit and the battery, although it is extremely small, eventually the overdischarge state There is a risk of becoming. Therefore, even after switching to the sleep mode, the battery voltage determination means continuously monitors the battery voltage, and when the battery voltage becomes lower than the voltage lower limit threshold, the mode return means returns from the sleep mode. It is.

  In this way, if the battery voltage falls below the voltage lower limit threshold, if the normal mode is restored from the sleep mode, the battery pack is switched to the shutdown mode by the shutdown mode switching means, further reducing the power consumption of the battery. This can prevent over-discharge of the battery.

  Further, the battery pack for electric tool is provided with a charge detection means for detecting that a charging device for charging the battery is connected, and the mode return means is connected to the charging device by the charge detection means. It is preferable to determine that the mode return condition is satisfied when it is detected. In this way, when the charging device is connected, the battery pack returns to the normal operating state, and monitoring by the monitoring circuit is also performed as usual, so that the battery is reliably monitored during charging. Will be able to.

  The above-described battery pack for an electric tool of the present invention is configured to be detachably attached to a tool main body that operates by receiving electric power supplied from the battery pack, so that the electric tool including the tool main body and the battery pack is provided. A tool can be constructed. According to the electric tool configured as described above, since the power consumption of the battery in the battery pack is effectively reduced, the frequency of charging the battery pack can be suppressed, and an electric tool that is easy to use for the user is provided. It becomes possible to provide.

Preferred embodiments of the present invention will be described below with reference to the drawings.
(1) Overall Configuration of Rechargeable Impact Driver FIG. 1 is a perspective view showing the appearance of a rechargeable impact driver 1 according to an embodiment to which the present invention is applied.

  The rechargeable impact driver 1 according to this embodiment includes a tool body 2 and a battery pack 10 that is detachably attached to the lower end of the tool body 2. The tool main body 2 is formed by assembling the left and right half housings 3 and 4 and includes a main body housing 6 with a handle portion 5 extending downward. A battery pack 10 is detachably attached to the lower end of the handle portion 5 of the main body housing 6.

  Further, the rear side of the main body housing 6 (left side in FIG. 1) is a motor storage portion 7 that stores a motor 65 (see FIG. 3; a direct current motor in this embodiment) that is a power source of the rechargeable impact driver 1. The speed reduction mechanism and the striking mechanism are accommodated in front of the motor accommodating portion 7. A chuck sleeve 8 for projecting a tool bit (not shown) is provided at the tip of the body housing 6 so as to be attached to the tip of the striking mechanism.

  Here, the striking mechanism includes, for example, a spindle that is rotated via a speed reduction mechanism, a hammer that rotates together with the spindle and that can move in the axial direction, and an anvil in which a tool bit is attached to the front end of the hammer. And operates as follows.

  That is, in the striking mechanism, when the spindle rotates with the rotation of the motor 65, the anvil rotates through the hammer to rotate the tool bit (for example, driver bit), and then the screw tightening by the tool bit proceeds to the anvil. When the load on the anvil increases, the hammer moves backward against the urging force of the coil spring and disengages from the anvil, and then rotates with the spindle while moving forward with the urging force of the coil spring and re-engages with the anvil. Apply intermittent blows and tighten them.

Since this striking mechanism is conventionally known (see, for example, Japanese Patent Application Laid-Open No. 2006-218605), detailed description thereof is omitted here.
The handle portion 5 of the main body housing 6 is provided with a trigger switch 9 that can be operated while the user holds the handle portion 5. When the user operates the trigger switch 9, the motor 65 rotates at a set rotation speed corresponding to the operation amount (pull amount) of the trigger switch 9 with the predetermined maximum rotation speed as an upper limit.

  The battery pack 10 includes a battery 31 (see FIG. 3) in which a plurality of battery cells having a predetermined voltage are connected in series. In the handle portion 5, there is housed a drive device that operates by receiving power supply from the battery 31 in the battery pack 10 and rotates the motor 65 when the trigger switch 9 is operated.

(2) Overall Configuration of Charging System Next, a charging system for charging the battery 31 in the battery pack 10 will be described with reference to FIG. FIG. 2 is a perspective view showing the charging system 30 of the present embodiment. As shown in FIG. 2, the charging system 30 includes a battery pack 10 and a charger 20 that charges the battery pack 10.

  The charger 20 generates a DC power source for charging at a predetermined voltage for charging the battery 31 from an external input power source (not shown) (for example, AC 100V power source or DC power source from a cigar socket of a vehicle). The charger 20 has a charging side mounting portion 12 to which the battery pack 10 is mounted on one end of the upper surface, and charges a predetermined position (inside the charging side mounting portion 12) in the charging side mounting portion 12. A side terminal 11 is provided. The charging-side terminal 11 is used to supply various signals between the charging-side positive terminal 71 and the charging-side negative terminal 72 (both refer to FIG. 4) for supplying a DC power supply for charging to the battery pack 10, and between the battery pack 10. It is the structure provided with the one or several charge side signal terminal containing the charger connection signal output terminal 73 (refer FIG. 4) for performing transmission / reception. In addition, the charger 20 is provided with a display unit 13 including a plurality of LEDs and the like for displaying the operating state of the charger 20 and the charging state of the battery pack 10 to the outside.

  The battery pack 10 has a battery side mounting portion 22 mounted on the charging side mounting portion 12 of the charger 20 or the lower end of the tool body 2 on one side surface. A battery side terminal 21 that is electrically connected to the charging side terminal 11 of the charger 20 or the tool side terminal (not shown) of the tool body 2 is provided at a predetermined position in the battery side mounting portion 22. .

  The battery-side terminal 21 includes a battery-side positive terminal 51 and a battery-side negative terminal 52 through which a charge / discharge current is passed, and a battery-side signal terminal 19. More specifically, the battery-side signal terminal 19 includes a plurality of terminals including at least a charger connection signal input terminal 53 and a discharge stop signal output terminal 54 (see FIGS. 3 and 4). One or a plurality of charge side signal terminals including a tool connection signal output terminal 73 (see FIG. 4), or one or a plurality of tool side signal terminals including a discharge stop signal input terminal 63 (see FIG. 3) in the tool body 2. Electrically connected.

  When the battery side mounting portion 22 of the battery pack 10 is mounted on the charging side mounting portion 12 of the charger 20, both terminals 11 and 21 are electrically connected. Thus, the battery 20 in the battery pack 10 can be charged by the charger 20.

  On the other hand, when the user uses the rechargeable impact driver 1 using the battery pack 10, the battery pack 10 is attached to the lower end of the tool body 2 in the same manner as when the battery pack 10 is attached to the charger 20. Thereby, the battery side positive terminal 51 and the battery side negative terminal 52 of the battery pack 10 are electrically connected to the tool side positive terminal 61 (see FIG. 3) and the tool side negative terminal 62 (see FIG. 3) of the tool body 2, respectively. The battery pack 10 is connected and can supply power to the tool body 2.

(3) Electrical Configuration of Rechargeable Impact Driver Next, the electrical configuration of the rechargeable impact driver 1 will be described with reference to FIG. FIG. 3 is a block diagram schematically showing the electrical configuration of the rechargeable impact driver 1. FIG. 3 shows a state where the battery pack 10 is attached to the tool body 2 and both are electrically connected.

  First, the electrical configuration of the battery pack 10 attached to the tool body 2 will be described. The battery pack 10 is equipped with various circuits such as various circuits for controlling discharge (power supply) to the tool body 2 and charging by the charger 20 and various circuits for monitoring the state of the battery 31. However, in FIG. 3, among the various circuits constituting the battery pack 10, only the circuit related to the state monitoring of the battery 31 is illustrated, and the circuit irrelevant to the monitoring operation is not illustrated.

  That is, each circuit in the battery pack 10 centered on the microcomputer 32 shown in FIG. 3 can be regarded as a monitoring circuit for monitoring the state of the battery 31 as a whole. Therefore, in the following description, detailed description regarding control during discharging to the tool body 2 and control during charging by the charger 20 is omitted, and the configuration and operation of the monitoring circuit shown in FIG. 3 will be described in detail.

  As shown in FIG. 3, the battery pack 10 of the present embodiment includes a battery 31, a microcomputer 32 that collectively performs various control functions in the battery pack 10 such as charge / discharge control and state monitoring of the battery 31, and the battery 31. The battery side regulator 33 for generating the battery side control power source (DC power source of the voltage Vcc) for operating various circuits in the battery pack 31 with the power of the input as the input, and the battery side positive terminal connected to the positive side of the battery 31 51, a battery-side negative terminal 52 connected to the negative side of the battery 31, a charger connection signal input terminal 53 and a discharge stop signal output terminal 54 constituting the battery-side signal terminal 19 (see FIG. 2). ing.

  The battery 31 is formed by connecting a plurality of battery cells B1, B2,..., Bn in series. In the present embodiment, each of the battery cells B1, B2,..., Bn is a lithium ion secondary battery having a rated voltage of 3.6 V, and ten of them are connected in series. Therefore, the voltage of the entire battery 31 (hereinafter referred to as “battery voltage”) Vbat is around 36 V at normal time.

  The electric power of the battery 31 is supplied to the tool body 2 via the battery side positive terminal 51 and the battery side negative terminal 52. When the battery 31 is charged by the charger 20, the charging DC power from the charger 20 is supplied to the battery 31 through the battery positive terminal 51 and the battery negative terminal 52 as described later.

  A battery voltage Vbat is input to the battery side regulator 33 that generates the battery side control power supply Vcc via the shutdown switch 40 and the diode D1. The shutdown switch 40 is turned on / off according to a shutdown signal from the microcomputer 32, and the details of the on / off control will be described later. As long as the battery 31 is normal, it is normally turned on. Therefore, normally, the battery voltage Vbat is input to the battery side regulator 33 via the shutdown switch 40 and the diode D1. The battery side regulator 33 generates a battery side control voltage Vcc based on the input battery voltage Vbat.

  As shown in FIG. 3, each circuit in the battery pack 10 includes a circuit that operates by the battery-side control power supply Vcc and a circuit that operates by the battery voltage Vbat. Therefore, the battery voltage Vbat input via the shutdown switch 40 is input to the anode of the diode D1 and also input to each circuit operating in the battery pack 10 based on the battery voltage Vbat.

  The battery pack 10 further includes a cell selection switch 38 for selectively outputting any one of voltages (hereinafter referred to as “cell voltages”) of the battery cells B1, B2,. A differential amplifier circuit 35 that amplifies the voltage of any one of the battery cells selected by the cell selection switch 38 and outputs it as a cell voltage signal, and a battery cell temperature (hereinafter referred to as “cell”) A temperature detection circuit 39 that detects and outputs a cell temperature signal, a battery voltage divided value Vz obtained by dividing the battery voltage Vbat by voltage dividing resistors Rx and Ry, and a predetermined first reference voltage Vr1. A voltage drop detection comparator 34 (which corresponds to the battery voltage determination means of the present invention) that compares and outputs the comparison result as a voltage drop detection signal; A current detection resistor R1 (corresponding to the signal acquisition means of the present invention) for detecting a discharge current at the time of discharging to the tool body 2 and a current detected by the current detection resistor R1 (ie, a voltage corresponding to the current value) A non-inverting amplifier circuit (corresponding to the signal amplifying means of the present invention) composed of an operational amplifier 37 and resistors R2, R3 and R4 for amplifying the signal) with a predetermined gain to generate a discharge current signal, A discharge detection comparator 36 (which corresponds to the discharge start detection means of the present invention) that compares the discharge current signal amplified by the amplifier circuit with a predetermined second reference voltage Vr2 and outputs the comparison result as a discharge detection signal; A charger detection transistor Tr1 (corresponding to the charge detection means of the present invention) for detecting that the charger 20 is connected, and a discharge stop signal (details are given later) ) And is provided with a discharge stop signal output transistor Tr2 for outputting to the tool body 2, the.

  In this embodiment, an NPN bipolar transistor is used as the charger detection transistor Tr1 and the discharge stop signal output transistor Tr2, but this is only an example. The same applies to a discharge stopping transistor Tr12 in the tool body 2 described later.

  The cell selection switch 38 operates by the battery voltage Vbat, and according to the cell selection signal from the microcomputer 32, the voltage of any one of the battery cells instructed by this cell selection signal is output and input to the differential amplifier circuit 35. As shown in the figure, a plurality of switches SW1a, SW2a, SW1b, SW2b, SW3a,..., SWna are provided.

  With such a configuration, when the battery cell B1 having the lowest potential is selected by the cell selection signal, for example, in the cell selection switch 38, between the negative electrode of the battery cell B1 and the non-inverting input terminal of the differential amplifier circuit 35. And the switch SW1b connected between the positive electrode of the battery cell B1 and the inverting input terminal of the differential amplifier circuit 35 are turned on, and all other switches are turned off. As a result, the voltage of the selected battery cell B <b> 1 is input from the cell selection switch 38 to the differential amplifier circuit 35.

  Further, for example, when the battery cell B2 connected to the positive electrode of the battery cell B1 is selected by the cell selection signal, the negative electrode of the battery cell B2 and the non-inverting input terminal of the differential amplifier circuit 35 are selected in the cell selection switch 38. The switch SW2a connected between the switch SW2a and the switch SW2b connected between the positive electrode of the battery cell B2 and the inverting input terminal of the differential amplifier circuit 35 are turned on, and all other switches are turned off. As a result, the voltage of the selected battery cell B <b> 2 is input from the cell selection switch 38 to the differential amplifier circuit 35.

  The differential amplifier circuit 35 is operated by the battery-side control power supply Vcc, a voltage input from the cell selection switch 38 (that is, a potential difference of any one selected battery cell) is amplified, and is sent to the microcomputer 32 as a cell voltage signal. Entered.

  The temperature detection circuit 39 is configured as a known temperature sensor including a temperature sensitive element such as a thermistor. The temperature sensitive element is provided in the vicinity of each battery cell in the battery 31. There are various ways of providing or how many temperature sensing elements are provided. For example, one temperature sensing element may be provided, and the detection result based on this temperature sensing element may be regarded as the cell temperature of each battery cell. Alternatively, a temperature sensing element may be provided for each battery cell, and the cell temperature may be detected individually for each battery cell. In this embodiment, for the sake of simplification of explanation, the former (in the case of one temperature sensing element) will be described as a premise.

  The voltage drop detection comparator 34 operates using the battery voltage Vbat (or the battery-side control power supply Vcc) as a power source. If the battery voltage divided value Vz is in a normal state equal to or higher than the first reference voltage Vr1, the comparator 34 for detecting voltage drop A voltage drop detection signal is output to the microcomputer 32. On the other hand, when the battery voltage Vbat decreases and the battery voltage divided value Vz becomes lower than the first reference voltage Vr1, a low (L) level voltage decrease detection signal is output to the microcomputer 32. This voltage drop detection comparator 34 detects this when the battery 31 is close to an overdischarge state in order to prevent the battery 31 from being overdischarged. Therefore, the first reference voltage Vr1 is appropriately set to a value that can be detected as being close to the overdischarge state. In the present embodiment, as an example, the first reference voltage Vr1 is set to a value when 25V is divided by the voltage dividing resistors Rx and Ry so that this can be detected when the battery voltage Vbat becomes lower than 25V. Yes.

  The current detection resistor R1 is provided in a current-carrying path from the battery-side negative terminal 52 to the negative electrode of the battery 31 (the negative electrode of the battery cell Bn having the lowest potential), and a voltage drop (due to a discharge current in the current detection resistor R1) Voltage signal) is input to the operational amplifier 37 constituting the non-inverting amplifier circuit.

  This non-inverting amplifier circuit basically includes an operational amplifier 37 that is operated by a battery-side control power supply Vcc, and a voltage signal detected by the current detection resistor R1 is input to the non-inverting input terminal. It has a well-known configuration that is connected to the ground (ground potential) via the resistor R2 and connected to the output terminal via the resistor R3. In the present embodiment, based on such a configuration, a resistor R4 is further connected between the inverting input terminal and the microcomputer 32, thereby switching the gain of the non-determination amplifier circuit to two types. It is possible.

  The resistor R4 has one end connected to the inverting input terminal of the operational amplifier 37 and the other end connected to the gain switching signal output port 47 of the microcomputer 32. The microcomputer 32 realizes gain switching of the non-inverting amplifier circuit by switching the gain switching signal output port 47 to either high impedance or L level output.

  That is, in a normal state where a high impedance signal is output as a gain switching signal, this is equivalent to the fact that the resistor R4 does not exist electrically as seen from the non-inverting amplifier circuit. Therefore, the gain of the non-inverting amplifier circuit at that time is 1+ (R3 / R2). The gain at this time is hereinafter referred to as a first gain. The first gain appropriately sets a relatively large discharge current (for example, a large current of several tens of A) in a steady state where power is supplied from the battery 31 to the tool body 2 and the tool body 2 is operating. It is set so that it can be detected.

  On the other hand, the microcomputer 32 outputs an L level signal as a gain switching signal when the discharge current becomes 0 A, as will be described later, so that the gain of the non-inverting amplifier circuit is larger than the first gain. Switch to a gain of 2. That is, when the gain switching signal becomes an L level signal and the other end of the resistor R4 (on the microcomputer 32 side) is connected to the ground potential, the gain (second gain) of the non-inverting amplifier circuit is 1+ { R3 / (R2 // R4)}. Here, (R2 // R4) represents a parallel combined resistance of the resistor R2 and the resistor R4. That is, the second gain is larger than the first gain.

  The discharge detection comparator 36 is operated by the battery-side control power supply Vcc, and outputs an H level discharge detection signal to the microcomputer 32 when the discharge current signal output from the operational amplifier 37 is equal to or higher than the second reference voltage Vr2. On the other hand, when the discharge current signal from the operational amplifier 37 becomes lower than the second reference voltage Vr2, an L level discharge detection signal is output to the microcomputer 32. The discharge detection comparator 36 is used to detect when power supply from the battery 31 to the tool body 2 is started by operating the trigger switch 9 of the tool body 2.

  When power supply to the tool body 2 is started, the discharge current immediately rises due to the characteristics of the load (here, the motor 65), and eventually reaches a steady state. Therefore, the second reference voltage Vr2 serving as a reference for detecting discharge may be a value close to a current value (for example, several tens of A) in the steady state, or about the current value in the steady state. Various values can be set such as 1/2. However, in this embodiment, when the discharge is started, the second reference voltage Vr2 is set to a low value (for example, 1 A) so that this can be detected quickly without waiting for a steady state.

  Here, since the discharge current signal input to the discharge detection comparator 36 is input from a non-inverting amplifier circuit composed of an operational amplifier 37 or the like, as described above, the discharge current signal is input to the non-inverting amplifier circuit. The level varies depending on the gain. In such a configuration, if the gain of the non-inverting amplifier circuit remains fixed at the first gain that can detect a large current appropriately, a small discharge current (for example, several A) at a low motor speed or the like. It is difficult to reliably detect.

  Therefore, in this embodiment, the microcomputer 32 switches the gain of the non-inverting amplifier circuit to the second gain when the discharge is completed, so that this can be detected even with a small discharge current. That is, the gain is set high so that a small current can be sufficiently detected. When the start of discharge is detected, the gain is switched to the first gain again so that a large current can be detected appropriately.

  The purpose of switching the gain of the non-inverting amplifier circuit in this way is basically to ensure that even a small current can be detected as described above. This is also for the purpose of quickly returning from the sleep mode to the normal operation state (wakeup) when the discharge is started again after the circuit shifts to the sleep mode as described later. By switching to the second gain at the end of the discharge, when the discharge is started again, the start of the discharge can be reliably detected even when the current value is still small, such as at a low motor speed. Can wake up.

  The charger detection transistor Tr1 has a base connected to the charger connection signal input terminal 53, an emitter connected to the ground potential, a collector connected to the battery side control power source Vcc via the resistor R5, and charging of the microcomputer 32. Connected to the detector connection detection signal input port 49. The operation of the charger detection transistor Tr1 will be described later with reference to FIG.

  The discharge stop signal output transistor Tr2 has a base connected to the discharge stop signal output port 50 of the microcomputer 32, an emitter connected to the ground potential, and a collector connected to the discharge stop signal output terminal 54.

  The microcomputer 32 has a known configuration including a CPU 56, a ROM 57, a RAM 58, a non-volatile memory 59, and the like as hardware, and uses a battery-side control power source Vcc generated by the battery-side regulator 33 as a power source. Operates and executes various controls according to various programs stored in the ROM 57.

  The microcomputer 32 outputs a voltage drop detection signal input port 41 to which a voltage drop detection signal from the voltage drop detection comparator 34 is input and a cell selection signal to the cell selection switch 38 as a port for inputting and outputting signals. Cell selection signal output port 42, cell voltage signal input port 43 to which the cell voltage signal from the differential amplifier circuit 35 is input, cell temperature signal input port 44 to which the cell temperature signal from the temperature detection circuit 39 is input, discharge detection The discharge detection signal input port 45 to which the discharge detection signal from the comparator 36 is input, the discharge current signal input port 46 to which the discharge current signal from the operational amplifier 37 is input, and the gain switching signal output port 47 to which the gain switching signal is output. A shutdown signal output for outputting a shutdown signal for controlling the shutdown switch 40 Port 48, charger connection detection signal input port 49 to which a charger connection detection signal is input from the charger detection transistor Tr1, and discharge stop signal output port 50 to which a discharge stop signal is output to the discharge stop signal output transistor Tr2. , Etc.

  Next, the electrical configuration of the tool body 2 in the rechargeable impact driver 1 will be described. As shown in FIG. 3, the tool body 2 includes a tool-side positive terminal 61 that is electrically connected to the battery-side positive terminal 51 of the battery pack 10, and a tool-side negative electrode that is electrically connected to the battery-side negative terminal 52. From the battery pack 10 when the terminal 62, the discharge stop signal input terminal 63 electrically connected to the discharge stop signal output terminal 54 of the battery pack 10, the trigger switch 9, and the trigger switch 9 are operated (turned on). A tool-side regulator 64 that generates a tool-side control power source (DC power source of voltage Vdd) for operating each part in the tool body 2 based on the input battery voltage Vbat, a tool-side positive terminal 61, and a tool-side negative terminal 62, a motor 65 connected between 62, an energization control transistor Tr11 connected in series with the motor 65, and a discharge stop from the battery pack 10. When the signal is input to the discharge stop signal input terminal 63, the energization control transistor Tr11 is turned off to stop the operation of the motor 65 (that is, the discharge from the battery 31 to the tool body 2 is stopped). And.

  Note that the energization control transistor Tr11 is a MOSFET in this embodiment. Further, a recirculation diode D11 for releasing residual energy of the motor 65 when the trigger switch 9 is turned off is connected to both ends of the motor 65.

  In the tool body 2 configured as described above, when the trigger switch 9 is operated, power supply from the battery 31 to the tool body 2 side is started, and thereby the tool side regulator 64 generates the tool side control power supply Vdd. Then, it is supplied to each part in the tool body 2. As a result, the tool control power source Vdd is applied to the base of the discharge stopping transistor Tr12 via the resistor R12, and the tool side control power source Vdd is also applied to its collector via the resistor R11.

  On the other hand, in the battery pack 10, when there is no abnormality in the battery 31 and the discharge to the tool body 2 may be permitted, the microcomputer 32 outputs an H level discharge stop signal (that is, discharges) from the discharge stop signal output port 50. Permitting signal) and the discharge stop signal output terminal 54 is set to L level (ground potential).

  Therefore, in the tool body 2, the base of the discharge stopping transistor Tr12 is also at the ground potential, and the discharge stopping transistor Tr12 is turned off. As a result, the energization control transistor Tr11 is turned on when the gate side control power supply Vdd is applied to the gate, and energization of the motor 65 is permitted.

(4) Electrical Configuration of Charging System Next, the electrical configuration of the charging system 30 for charging the battery 31 of the battery pack 10 shown in FIG. 2 will be described with reference to FIG. FIG. 4 is a block diagram schematically showing the electrical configuration of the charging system 30.

  As shown in FIG. 4, when charging the battery 31, the battery pack 10 is attached to the charger 20. The charger 20 includes a charging side positive terminal 71 electrically connected to the battery side positive terminal 51 of the battery pack 10, a charging side negative terminal 72 electrically connected to the battery side negative terminal 52, and the battery pack 10. A converter for generating a DC power supply for charging from a charger connection signal output terminal 73 electrically connected to the charger connection signal input terminal 53 and an external input power input via two input power supply terminals 74 and 75 76.

  Although not shown, the charger 20 includes a control circuit that performs various controls such as controlling the generation of a DC power supply for charging by the converter 76. Further, the converter 76 includes a charging side regulator 77 that generates a charging side control power source (DC power source of the voltage Vdd), and each unit in the charger 20 including the control circuit is operated by the charging side control power source Vdd. To do.

  The charger control power supply Vdd is also input to the battery pack 10 from the charger connection signal output terminal 73 as a charger connection signal. The charger connection signal is input to the base of the charger detection transistor Tr1 via the charger connection signal input terminal 53 in the battery pack 10, whereby the charger detection transistor Tr1 is turned on and the potential of the collector thereof is turned on. That is, the charger connection detection signal input to the microcomputer 32 becomes L level.

  That is, when the charger 20 is not connected to the battery pack 10, the charger connection detection signal input to the microcomputer 32 becomes H level by the battery side control power supply Vcc input via the resistor R5. On the other hand, when the charger 20 is connected, the charger detection transistor Tr1 is turned on by the charger connection signal (voltage Vdd) from the charger 20 as described above, and the charger connection detection signal to the microcomputer 32 is L level. Therefore, the microcomputer 32 can determine whether or not the charger 20 is connected (specifically, the battery 31 is being charged) based on the level of the charger connection detection signal.

  Further, the charger connection signal (voltage Vdd) input from the charger 20 to the battery pack 10 is also input to the battery side regulator 33 via the diode D2. The battery-side regulator 33 basically generates the battery-side control power source Vcc based on the battery voltage Vbat, but from the charger 20 when the shutdown switch 40 is turned off and the battery voltage Vbat is not input. When the charger connection signal (that is, the charging side control power supply Vdd) is input, the battery side control power supply Vcc is generated based on the charging side control power supply Vdd.

(5) Battery monitoring control processing in the battery pack In the battery pack 10 configured as described above, the microcomputer 32 constitutes the monitoring circuit of the present invention, and the sleep mode switching means and mode return means of the present invention. And during the normal operation (normal operation state), the cell temperature, the cell voltage of each battery cell, The battery 31 is monitored based on the current when the battery 31 is charged and discharged. The configuration for monitoring the charging current during charging is not described in this embodiment. Further, the monitoring items of the battery 31 by the microcomputer 32 are not limited to the above-described cell voltage, cell temperature, and charge / discharge current, but may include other items.

In other words, during normal operation, the various components of the monitoring circuit in the battery pack 10 shown in FIG.
On the other hand, when a predetermined condition to be switched to the sleep mode is satisfied, such as when the power supply to the tool body 2 is not performed, the microcomputer 32 switches the entire monitoring circuit including itself to the sleep mode, and starts normal operation. Also, the power consumption of the battery 31 is kept low. However, the power supply to each part in the battery pack 10 including the microcomputer 32 is not completely stopped during the sleep mode, and the minimum necessary operation for returning from the sleep mode and wake-up continues. Is called.

  Specifically, after switching to the sleep mode, the microcomputer 32 determines whether or not the discharge is started based on the current detection signal from the discharge detection comparator 36, and charges from the charger detection transistor Tr1. Based on the battery connection detection signal, whether or not the charger 20 is connected and the battery voltage divided value Vz based on the voltage drop detection signal from the voltage drop detection comparator 34 is lower than the first reference voltage Vr1. Is determined (that is, whether or not the battery voltage Vbat is lower than 25V in this example).

  Thereby, after switching to the sleep mode, whether the discharge from the battery 31 is started, the charger 20 is connected, or the battery voltage divided value Vz becomes lower than the first reference voltage Vr1. When such a return condition is satisfied, the normal operation state is restored again from the sleep mode. As will be described later, the microcomputer 32 controls the discharge (power supply to the tool body 2) while monitoring the state of the battery 31 when the microcomputer 32 returns due to the start of discharge. When the battery 20 is restored due to the connection, the charging monitoring mode is entered, and various controls relating to charging, monitoring of the state of the battery 31 being charged, and the like are performed. When the battery voltage is reduced due to a decrease, the battery 31 shifts to a shutdown mode in which the power consumption of the battery 31 is smaller than that in the sleep mode.

  Specifically, the transition to the shutdown mode is performed by turning off the shutdown switch 40 by a shutdown signal. Therefore, when the shutdown mode is entered, the battery voltage Vbat is not supplied to the entire monitoring circuit in the battery pack 10 including the battery side regulator 33, and the operation of the entire monitoring circuit including the microcomputer 32 is completely stopped.

  Even if the battery voltage division value Vz is lower than the first reference voltage Vr1, if the operation necessary for the wakeup is continued as described above, the power consumption is sufficiently higher than that in the normal operation. Although it is low, since it is a fact that battery power is consumed, the discharge of the battery 31 further progresses slowly, but the battery 31 may be in an overdischarged state. Therefore, in this embodiment, when the battery voltage division value Vz decreases and becomes lower than the first reference voltage Vr1, priority is given to prevention of overdischarge of the battery 31 over the function of the monitoring circuit, and the shutdown switch 40 is set. The power supply from the battery 31 to each part in the battery pack 10 is completely cut off.

  Next, battery monitoring control processing executed by the microcomputer 32 in the battery pack 10 of the present embodiment configured as described above will be described with reference to FIG. FIG. 5 is a flowchart showing a battery monitoring control process executed by the microcomputer 32 in the battery pack 10. In the microcomputer 32 in the battery pack 10, the CPU 56 reads a control processing program from the ROM 57 and executes processing according to this program.

  When the battery monitoring control process is started, it is first determined whether or not the charger 20 is connected (S110). This determination is made based on the charger connection detection signal input to the charger connection detection signal input port 49 of the microcomputer 32. If the charger connection detection signal is at the H level, the charger 20 is not connected. If it is L level, it is determined that the charger 20 is connected.

  When it is determined that the charger 20 is connected (S110: YES), the monitoring circuit in the battery pack 10 including the microcomputer 32 enters the charge monitoring mode (S120). In this charge monitoring mode, the microcomputer 32 sets a charge monitoring mode flag in the RAM 58 and controls the charging of the battery 31 while monitoring the state of the battery 31.

  On the other hand, when it is determined that the charger 20 is not connected (S110: NO), it is determined whether or not the battery voltage Vbat is lower than 25V (S130). This determination is made based on the voltage drop detection signal from the voltage drop detection comparator 34. If it is determined that the voltage drop is lower than 25V (S130: YES), the battery 31 may be in an overdischarged state. After performing the data store, the process shifts to the shutdown mode (S370). That is, all the power supply from the battery 31 into the battery pack 10 is stopped by turning off the shutdown switch 40.

  The data store refers to various data stored in the RAM 58 or the like by the microcomputer 32 (for example, the number of times of charging, the maximum value / maximum value of the cell temperature detected so far, the maximum value / minimum value of the discharge current, etc. (History) is stored in the non-volatile memory 59.

  After entering the shutdown mode in this way, the shutdown mode is maintained unless the charger 20 is connected and charging is started. When the charger 20 is connected, the charging-side control power supply Vdd in the charger 20 is input to the battery-side regulator 33 via the diode D2. Generation of the original battery side control power supply Vcc is started, and the battery side control power supply Vcc is input to the microcomputer 32. Thereby, the microcomputer 32 starts various controls (normal operation) including the battery monitoring control process.

  When the battery voltage Vbat is determined to be 25 V or higher in the determination process of S130 (S130: NO), whether or not the cell voltage is lower than 2.0 V for each of the battery cells B1, B2,. Is determined (S140). At this time, if the cell voltages of all the battery cells are 2.0V or more (S140: NO), a status check is performed (S150), but there is a battery cell whose cell voltage is lower than 2.0V in any one of them. If this is the case (S140: YES), the discharge inhibition mode is entered (S320).

  Specifically, a discharge inhibition mode flag is set in the RAM 58 in the microcomputer 32 and an L level discharge stop signal is output from the discharge stop signal output port 50. As a result, the discharge stopping transistor Tr12 in the tool body 2 is turned on, the energization control transistor Tr11 is turned off, and energization to the motor 65 (that is, discharging from the battery 31) is stopped.

On the other hand, in the status check in S150, various data indicating the state of the battery 31 such as the battery voltage Vbat, the cell voltage, the cell temperature, and the discharge current are acquired.
Based on the discharge current signal input to the discharge current signal input port 46, it is determined whether or not the discharge current is greater than 80A (S160). If greater than 80A (S160: YES), the discharge stop mode is entered. (S310). Specifically, in this discharge stop mode, a discharge stop mode flag is set in the RAM 58 in the microcomputer 32, and an L level discharge stop signal is output from the discharge stop signal output port 50 in the same manner as in the discharge inhibition mode in S320. By doing so, the discharge from the battery 31 to the tool body 2 is stopped. And it returns to the process after the status check of S150 again.

  If the discharge current is 80 A or less (S160: NO), based on the cell temperature signal input to the cell temperature signal input port 44, it is determined whether the cell temperature is higher than 80 ° C. (S170). When the cell temperature is higher than 80 ° C. (S170: YES), after entering the discharge stop mode (S310), the process returns to the process after the status check of S150 again. If the cell temperature is 80 ° C. or lower (S170: NO), it is determined again whether or not the cell voltage is lower than 2.0V (S180) as in S140. If there is a low battery cell (S180: YES), a discharge inhibition mode is entered (S320), and if all battery cells are 2.0 V or more (S180: NO), a discharge permission mode is entered (S190). Specifically, a discharge permission mode flag is set in the RAM 58.

  In other words, in this embodiment, when discharge is performed, if the discharge current is 80 A or less, the cell voltages of all the battery cells are 2.0 V or more, and the cell temperature is 80 ° C. or less, the discharge is permitted. Assuming that the conditions have been satisfied, the power supply to the tool body 2 is continued and the operation of the tool body 2 is continued.

  Even after entering the discharge permission mode, the monitoring of the battery 31 is continued. That is, after the transition to the discharge permission mode in S190, it is first determined whether or not the discharge current is 0 A (S200). If discharging is in progress, that is, if the tool is being used, discharging continues (S200: NO), and the process returns to the processing after the status check in S150 again. On the other hand, when the operation of the trigger switch 9 is released and the discharge from the battery 31 to the tool body 2 is completed and the discharge current becomes 0 A (S200: YES), an L level gain switching signal is output from the gain switching signal output port 47. The gain of the non-inverting amplifier circuit composed of the operational amplifier 37 and the like is switched from the first gain in the initial state to a second gain larger than this (S210).

  As a result, when the discharge is started again, the start of the discharge can be quickly detected even if the current value is still small, such as at a low motor speed. Note that the determination of whether or not the current is 0 A in S200 does not mean that the discharge current from the battery 31 is completely 0 A, but the state in which the discharge of the battery 31 accompanying the power supply to the tool body 2 has been completed ( That is, it means that the supply to the tool body 2 is 0A). Therefore, in practice, a specified current value for determining the end of discharge is set based on the electric power consumed in each circuit in the battery pack 10 including the microcomputer 32. The process proceeds to S210 when it is determined that the error has occurred.

  Then, after switching to the second gain in S210 so that even a small discharge current can be detected accurately, it is determined again whether or not the discharge current is greater than 0 A (S220). That is, whether or not the discharge from the battery 31 to the tool main body 2 has been completed is confirmed after S200.

  At this time, when it is determined that the discharge current is larger than 0 A and the discharge to the tool body 2 is still continuing (S220: YES), the gain of the non-inverting amplifier circuit is switched to the first gain again (S230). ), The process returns to S150. On the other hand, if it is determined that the discharge current to the tool body 2 is 0 A (S220: NO), it is determined whether the condition for entering the sleep mode is satisfied, in other words, whether the discharge has ended. Various determinations in S240 to S270 are performed to determine whether or not the battery 31 is in a stable state.

  That is, it is first determined whether or not the cell temperature has a change amount dT / dt smaller than, for example, 5 ° C. (S240). Here, if the battery 31 is in a normal state, the cell temperature should gradually decrease after the end of discharge. However, after an end of discharge, when the battery 31 is in an unstable state until the battery 31 becomes stable, for example, when the above-described light short occurs in a certain battery cell, the cell temperature rapidly increases. . Therefore, in S240, an abnormality of the battery cell is detected by detecting a sudden rise in cell temperature accompanying such an abnormality of the battery cell.

  If the cell temperature change amount dT / dt is 5 ° C. or more in S240 (S240: NO), it is determined that the battery cell is in an abnormal state (abnormality detection), and the charge / discharge prohibit mode is set to prohibit both charging and discharging. Transition is made (S380). After shifting to the charge / discharge inhibition mode, the battery pack 10 is in a state where neither charging nor discharging is possible, and the user can no longer use the battery pack 10.

  If it is determined in S240 that the cell temperature variation dT / dt is smaller than 5 ° C. (S240: YES), then, for each battery cell, the cell voltage variation dV / dt is, for example, from −100 mV. It is determined whether or not it is larger (S250). For example, when a light short circuit occurs in a battery cell, the voltage of the battery cell rapidly decreases. Therefore, in S250, the battery cell abnormality is detected by detecting such a sudden drop in the cell voltage accompanying the abnormality of the battery cell.

  If it is determined in S250 that any one of the cell voltage changes dV / dt is -100 mV or less (that is, the decrease tendency is large) (S250: NO), the battery cell is in an abnormal state. Thus, the charging / discharging prohibition mode for prohibiting both charging and discharging is entered (S380).

  If it is determined in S250 that the cell voltage variation dV / dt is greater than −100 mV (that is, the decrease tendency is small) for all battery cells (S250: YES), then, for each battery cell Then, it is determined whether or not the change amount dV / dt of the cell voltage is 0 or less (S260). At this time, if the amount of change in the cell voltage is greater than 0 (that is, the cell voltage has increased) (S260: NO), although no abnormality has occurred in the battery cell, the battery 31 is still immediately after the end of the discharge. Is determined to be unstable, and the process returns to S150 and subsequent steps.

  On the other hand, when the change amount of the cell voltage is 0 or less, that is, when it is determined that the increase in the cell voltage after the end of discharge has converged and stabilized (S260: YES), the cell temperature T is further increased. It is determined whether the temperature is lower than 60 ° C. (S270). This determination in S270 is a determination for the value of the cell temperature itself, unlike the determination of the change in cell temperature in S250. If the cell temperature is 60 ° C. or higher (S270: NO), it is determined that the battery 31 is not yet stable, and the process returns to S150 and subsequent steps. On the other hand, if it is determined that the cell temperature is lower than 60 ° C. (S270: YES), the microcomputer 32 switches the entire monitoring circuit including itself to the sleep mode, assuming that the condition for shifting to the sleep mode is satisfied (S270: YES) S280).

  During the sleep mode, various monitoring operations performed by the monitoring circuit, including cell voltage monitoring, cell temperature monitoring, and charge / discharge current monitoring, which are performed during normal operation, are basically stopped by the microcomputer 32. Various controls are also basically stopped, but as described above, at least functions necessary for returning from the sleep mode to the normal operation state are continued.

  Then, after switching to the sleep mode, when the discharge condition from the battery 31 is started, the charger 20 is connected, or the battery voltage Vbat is lower than 25V is satisfied. (S290), the sleep mode is waked up to the normal operation state (S300), and the processing from S110 onward is performed again. In the wake-up process of S300, a process of returning the gain that has been switched to the second gain in S210 to the first gain is also performed.

  In this case, for example, when the battery pack 10 is connected to the battery pack 10 to return from the sleep mode, the process proceeds from S110 to S120 and enters the charge monitoring mode. Further, for example, when the battery voltage Vbat is lower than 25V, the process returns from the sleep mode, and after proceeding from S110 to S130, it is determined that the battery voltage Vbat is lower than 25V in the determination process of S130 (S130: YES), the process proceeds to the data store and the transition process to the shutdown mode in S370.

  Further, after shifting to the discharge inhibition mode in S320, the process proceeds to S330, and it is determined whether or not the same determination process as S240, that is, whether the cell temperature change amount dT / dt is smaller than 5 ° C. If the change dT / dt of the cell temperature is 5 ° C. or higher (S330: NO), it is determined that the battery cell is in an abnormal state, and a transition is made to a charge / discharge inhibition mode that inhibits both charging and discharging (S380). . On the other hand, if it is determined that the cell temperature change amount dT / dt is smaller than 5 ° C. (S330: YES), the process proceeds to S340, where the same determination process as S250, that is, the cell voltage for each battery cell. It is determined whether or not the change amount dV / dt is greater than −100 mV.

  If any one of the cell voltage changes dV / dt is determined to be −100 mV or less (that is, the decrease tendency is large) (S340: NO), it is determined that the battery cell is in an abnormal state. Then, the charging / discharging prohibition mode for prohibiting both charging and discharging is performed (S380). On the other hand, if it is determined that the cell voltage variation dV / dt is greater than −100 mV (that is, the decrease tendency is small) for all the battery cells (S340: YES), the process proceeds to S350 and is exactly the same as S260. Determination processing, that is, whether or not the cell voltage change amount dV / dt is 0 or less is determined for each battery cell.

  If the change amount of the cell voltage is greater than 0 (S350: NO), the process returns to S320 and subsequent steps. On the other hand, when the change amount of the cell voltage is 0 or less (S350: YES), the process proceeds to S360, where it is determined whether or not the same determination process as S270, that is, whether the cell temperature T is lower than 60 ° C.

  And when cell temperature is 60 degreeC or more (S360: NO), it returns to the process below S320 again. On the other hand, when it is determined that the cell temperature is lower than 60 ° C. (S360: YES), the process proceeds to S370, and the process of shifting to the data store and the shutdown mode is performed.

(6) Effects of First Embodiment According to the battery pack 10 of the present embodiment described above, after the discharge to the tool body 2 is completed (S220: NO), the cell temperature change amount dT / dt is 5 ° C. It is smaller and the temperature change is in a stable state (S240: YES), the change amount dV / dt of the cell voltage is greater than −100 mV for all the battery cells constituting the battery 31 (S250: YES) and 0 When all of the following conditions are satisfied (S260: YES), and the cell temperature is lower than 60 ° C. and the temperature is stable (S270: YES), The battery pack 10 is switched to the sleep mode (S280). Therefore, it is possible to effectively reduce the power consumption of the battery 31 while monitoring the state of the battery 31 as necessary and sufficiently after the discharge to the tool body 2 is finished and until the battery 31 is stabilized.

  In addition, it is not only determined that the condition for switching to the sleep mode is satisfied after the discharge is completed, but also when the cell temperature is rapidly increasing (S240: NO), or the amount of change in the cell voltage is rapidly decreasing. In the case (S250: NO), it is determined that the battery 31 is in an abnormal state, and thereafter, the battery pack 10 is made unusable. For this reason, it is possible to reliably detect an abnormality such as a light short-circuit and take an appropriate measure while realizing an effective reduction in power consumption.

  Further, while the discharge to the tool body 2 is being performed, the gain of the non-inverting amplifier circuit composed of the operational amplifier 37 or the like is set as the first gain, and when the discharge to the tool body 2 is completed, the gain is set to the first gain. The gain is switched to a second gain that is greater than one. Therefore, while discharging from the battery 31 to the tool body 2 is performed, a discharging current (a relatively large current of several tens of A) during the discharging can be reliably detected. After the end of discharge, a larger second gain amplifies even a small discharge current to a large value. Therefore, when the discharge is started again, the discharge current is low, such as at low motor speed. This can be reliably detected and can be quickly returned from the sleep mode.

  Further, in this embodiment, even after switching to the sleep mode, it is continuously determined whether or not the battery voltage divided value Vz is lower than the first reference voltage Vr1, and becomes lower than the first reference voltage Vr1. In the event of a failure, it returns from sleep mode and then switches to shutdown mode. That is, when the remaining capacity of the battery 31 decreases and the battery voltage becomes lower than 25V, the battery 31 shifts to the shutdown mode and discharge from the battery 31 is completely stopped (however, excluding spontaneous discharge). Therefore, it becomes possible to prevent the battery 31 from being overdischarged.

(7) Other Embodiments The embodiment of the present invention has been described above. However, the embodiment of the present invention is not limited to the above embodiment, and various embodiments are included as long as they belong to the technical scope of the present invention. It goes without saying that the form of can be adopted.

  For example, as a condition for switching to the sleep mode after the end of discharging, in the above-described embodiment, as shown in the battery monitoring control process of FIG. 5, the cell temperature change amount dT / dt is in a temperature stable state smaller than 5 ° C. (S240: YES), the cell voltage change amount dV / dt is greater than −100 mV (S250: YES) and 0 or less for all battery cells (S260: YES), and the cells The temperature T is lower than 60 ° C. (S270: YES), and when all of these are established, the mode is switched to the sleep mode. For example, the cell temperature change amount dT / dt is smaller than 5 ° C. Switching to sleep mode only when the temperature is stable (S240: YES), or for all battery cells Only when the cell voltage change amount dV / dt is greater than −100 mV (S250: YES), the voltage stable state is switched to the sleep mode, or when both the conditions of S240 and S250 are satisfied, the sleep mode is switched. For example, various combinations can be adopted as the condition for switching to the sleep mode. Alternatively, in addition to the condition determination in S240 to S270, another condition determination may be performed.

  However, the monitoring operation can be surely continued during the period in which the battery 31 is not stable immediately after the end of discharging, and after the battery 31 enters the stable state, the sleep mode is quickly shifted to effectively reduce the power consumption. More preferably, the necessary and sufficient condition determination shown in S240 to S270 in the above embodiment is performed.

  Further, as specific determination reference values in the determination processes of S240 to S270, the values shown in FIG. 5 (5 ° C. of S240, −100 mV of S250, 0 of S260, 60 ° C. of S270) are merely examples. A numerical value different from this may be set as appropriate. The same applies to the determination reference values in the determination processes of other S130, S140, S160, S170, S180, S200, S220, and S330 to S360.

  In the above embodiment, the gain of the non-inverting amplifier circuit composed of the operational amplifier 37 can be switched between two types according to the gain switching signal from the microcomputer 32. Alternatively, the gain can be switched between three or more types. Alternatively, it may be configured to be able to change continuously.

  In the above embodiment, the discharge current signal from the operational amplifier 37 is input to the discharge detection comparator 36. However, the voltage signal on the upstream side of the current detection resistor R1 (that is, input to the operational amplifier 37). Signal) may be input to the discharge detection comparator 36 as well.

  In the above embodiment, the battery pack 10 has been described on the assumption that the monitoring circuit is configured as a whole by the circuits shown in FIG. 3 including the microcomputer 32. A circuit (dedicated IC or the like) is provided, and in the sleep mode, the operation of the dedicated IC or the like is stopped by stopping power supply to the dedicated IC or the like, and the microcomputer 32 is operated with low power consumption (for example, sleep mode). The operation may be limited to a function that only monitors whether the return condition from the mode is satisfied.

  In addition, the configuration of the battery 31 is a configuration in which ten battery cells are connected in series in the above embodiment, but this is merely an example, and the number of battery cells constituting the battery 31 is not particularly limited. The battery may include a single battery cell, or battery cells connected in series and parallel. Needless to say, the voltage of one battery cell and the battery voltage are not limited to the values exemplified in the above embodiment.

  Moreover, in the said embodiment, although the case where each battery cell which comprises the battery 31 was a lithium ion secondary battery was mentioned as an example, this was also an example to the last, and a battery cell is other than a lithium ion secondary battery. The present invention can be similarly applied to a case of a case or a primary battery.

It is a perspective view showing the appearance of the rechargeable impact driver of an embodiment. It is a perspective view which shows the charging system of embodiment. It is a block diagram which shows simply the electrical constitution of a rechargeable impact driver. It is a block diagram which shows simply the electric constitution of a charging system. It is a flowchart showing the battery monitoring control process performed with a battery pack.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Rechargeable impact driver, 2 ... Tool main body, 9 ... Trigger switch, 10 ... Battery pack, 11 ... Charge side terminal, 12 ... Charge side mounting part, 13 ... Display part, 19 ... Battery side signal terminal, 20 ... Charge 21 ... battery side terminal, 22 ... battery side mounting part, 30 ... charging system, 31 ... battery, 32 ... microcomputer, 33 ... battery side regulator, 34 ... voltage drop detection comparator, 35 ... differential amplifier circuit, 36 DESCRIPTION OF SYMBOLS: Discharge detection comparator 37 ... Operational amplifier 38 ... Cell selection switch 39 ... Temperature detection circuit 40 ... Shutdown switch 41 ... Voltage drop detection signal input port 42 ... Cell selection signal output port 43 ... Cell voltage signal input Port 44 cell temperature signal input port 45 discharge detection signal input port 46 discharge current signal Power port, 47 ... gain switching signal output port, 48 ... shutdown signal output port, 49 ... charger connection detection signal input port, 50 ... discharge stop signal output port, 51 ... battery side positive terminal, 52 ... battery side negative terminal, 53 ... Charger connection signal input terminal, 54 ... Discharge stop signal output terminal, 56 ... CPU, 57 ... ROM, 58 ... RAM, 59 ... Non-volatile memory, 61 ... Tool side positive terminal, 62 ... Tool side negative terminal, 63 DESCRIPTION OF SYMBOLS ... Discharge stop signal input terminal, 64 ... Tool side regulator, 65 ... Motor, 71 ... Charge side positive terminal, 72 ... Charge side negative terminal, 73 ... Charger connection signal output terminal, 74, 75 ... Input power supply terminal, 76 ... Converter, 77 ... Charge side regulator, B1, B2, ..., Bn ... Battery cell, D1, D2, D11 ... Diode, R1 ... Current detection resistor, R2, 3, R4, R5, R11, R12 ... resistor, Rx, Ry ... dividing resistors, Tr1 ... charger detection transistor, Tr2 ... discharge stop signal output transistor, Tr11 ... energization control transistors, Tr12 ... discharge stop transistor

Claims (12)

A battery pack for a power tool,
A battery having at least one battery cell;
The battery is operated by receiving power from the battery, and at least discharge current detection means for detecting a discharge current from the battery, cell voltage detection means for detecting the voltage of the battery cell, and temperature detection for detecting the temperature of the battery And a monitoring circuit for monitoring the state of the battery based on the detection result by each detection means,
In the case where it is detected by the monitoring circuit that the discharge current has reached a discharge end state that is equal to or less than a predetermined specified current value, the monitoring circuit further determines the amount of change in the voltage of the battery cell in advance. It is detected that at least one of a voltage stable state within a predetermined voltage change amount stable range and a temperature stable state where the battery temperature change amount is within a predetermined temperature change amount stable range. A sleep mode switching means for switching the battery pack for the electric tool to the sleep mode by stopping at least part or all of the operation of the monitoring circuit,
A battery pack for an electric tool, comprising: The battery pack for an electric tool according to claim 1,
The monitoring circuit detects that the voltage is stable when all the battery cells included in the battery have a voltage change amount in the voltage change amount stable range. Battery pack for tools. The battery pack for an electric tool according to claim 1 or 2,
The sleep mode switching means is when the discharge end state is detected by the monitoring circuit, and when the voltage stable state and the temperature stable state are both detected by the monitoring circuit, A battery pack for electric tools characterized by switching to The battery pack for an electric tool according to claim 3,
The sleep mode switching means is the case where the discharge end state is detected by the monitoring circuit, and further, the voltage stable state and the temperature stable state are both detected by the monitoring circuit, and the temperature of the battery is set in advance. When it is detected that the temperature is lower than a predetermined temperature threshold, switching to the sleep mode is performed. It is a battery pack for electric tools in any one of Claims 1-4,
The monitoring circuit detects at least one of a change in the voltage of the battery cell outside the stable voltage change amount range or a change in the temperature of the battery outside the stable temperature change amount range. When the battery pack for an electric tool is determined, the battery is determined to be in an abnormal state. A battery pack for an electric tool according to any one of claims 1 to 5,
After the switching to the sleep mode by the sleep mode switching unit, when a predetermined mode return condition is satisfied in the power tool battery pack, the power tool battery pack is normally moved from the sleep mode. A battery pack for an electric tool, characterized by comprising mode return means for returning to the operating state. The battery pack for an electric tool according to claim 6,
The mode return means has discharge start detection means for detecting that discharge from the battery has started, and the mode return condition is satisfied when the start of discharge is detected by the discharge start detection means A battery pack for a power tool characterized by being judged. The battery pack for an electric tool according to claim 7,
The discharge current detection means includes a signal acquisition means for acquiring an electric signal corresponding to the magnitude of the discharge current, and a signal for amplifying the electric signal acquired by the signal acquisition means with a predetermined first gain. And amplifying means, and configured to continue the operation after the sleep mode switching means is switched to the sleep mode,
The discharge start detection means is configured to detect that the discharge has started based on the electric signal after amplification by the signal amplification means,
The power tool further comprising: gain switching means for switching the gain of the signal amplifying means to a second gain larger than the first gain when the monitoring circuit detects the discharge end state. Battery pack. The battery pack for an electric tool according to claim 8,
The gain switching means switches the gain to the first gain again when the start of discharge is detected by the discharge start detection means after switching to the second gain. Battery pack for tools. It is a battery pack for electric tools in any one of Claims 6-9,
Battery voltage determining means that operates also in the sleep mode and determines whether or not the voltage of the battery is lower than a predetermined voltage lower limit threshold;
When the battery voltage determination means determines that the battery voltage has become lower than the voltage lower limit threshold, the power tool battery pack is connected to the battery pack for the electric tool more than in the sleep mode. Shutdown mode switching means for switching to a shutdown mode with low power consumption of the battery,
The battery for power tools, wherein the mode return means determines that the mode return condition is satisfied when the battery voltage determination means determines that the voltage of the battery is lower than the voltage lower limit threshold. pack. It is a battery pack for electric tools in any one of Claims 6-10,
Charge detecting means for detecting that the charging device for charging the battery is connected to the battery pack for the electric tool,
The battery pack for an electric tool, wherein the mode return means determines that the mode return condition is satisfied when connection of the charging device is detected by the charge detection means. A battery pack for an electric tool according to any one of claims 1 to 11,
A tool main body that is detachably mounted on the power tool battery pack and operates by receiving power from the power tool battery pack;
An electric tool comprising:

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