JP2006286508A - Lithium battery pack and charging device for lithium battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithium battery pack capable of shortening charging time even if the battery temperature T of the lithium battery is at a lower range than a charging optimal temperature range (for example, 15≤T<35°C) and a charging device for lithium battery pack. <P>SOLUTION: The lithium battery pack 2 is equipped with a temperature adjusting heater 101 in a case 2K. The charger 200 for lithium battery forms a temperature adjustment mechanism 202 by the temperature adjusting heater 101 and a wind fan 6 housed in the charger main body. When the battery temperature T of the lithium battery pack 2 is at a lower range than the charging optimal temperature range (-15≤T<55°C), the charger 200 charges by a charging current value corresponding to the surrounding temperature T of the lithium battery pack 2, while controlling the battery temperature T of the lithium battery pack 2 by the heater 101 and the fan 6. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a secondary battery in which lithium species are deeply involved in the battery reaction, a so-called lithium battery pack including a lithium secondary battery including a lithium ion secondary battery, and a charging device for charging the lithium battery pack. The present invention relates to a lithium battery pack having a function of adjusting the ambient temperature of the lithium battery pack, and a lithium battery charger.

  With the development of portable devices, nickel-cadmium batteries are used as power sources for electronic devices such as portable radio CD players, portable video cameras, portable personal computers, communication devices such as mobile phones, and cordless power tools. Secondary batteries with higher capacities such as nickel and hydrogen batteries are being used. As one of high-capacity secondary batteries, attention is focused on the use of lithium batteries that can extract more electricity than other secondary batteries for portable devices.

  The nominal cell voltage of lithium batteries is about 2-3 times higher than that of nickel-cadmium batteries and nickel-hydrogen batteries, which are widely used for practical purposes, and its energy density is about 3 times that of nickel-cadmium batteries. And it has the feature of being small and lightweight. Furthermore, it has good discharge efficiency, can be discharged even in a relatively low temperature environment, and can obtain a stable voltage over a wide temperature range.

  The applicant of the present application pays attention to the characteristics of these lithium batteries, adopts a lithium battery pack as a motor drive power source of a cordless electric tool such as an impact driver, and has studied a reduction in size and weight of the cordless electric tool. In particular, in a cordless electric tool, since an operator uses it while holding it at a work site for a long time, it is required to reduce the weight of the entire tool as much as possible, and the adoption of a lithium battery is advantageous. Further, unlike cordless power tools, unlike other electronic devices, a large motor is used, and therefore, it is advantageous to employ a high capacity (high discharge capacity) lithium battery as a drive source.

  A charger for charging a battery pack used for a cordless power tool is usually carried into a work site such as a construction site together with the cordless power tool. If the power supply capacity of the battery pack decreases due to long-term use at the work site, the battery pack must be charged and then used for the cordless power tool body. Furthermore, the charger may be used at a work site where the working environment temperature of the battery pack is not suitable for the charging characteristics of the battery pack, such as in a cold region. For this reason, the power tool charger is required to have a charging function (rapid charging) for charging the battery pack as quickly as possible, and at a controlled environmental temperature that does not impair the charging / discharging function of the battery pack. It is required to charge with.

  Among conventional charging devices, in particular, a charging device having a function of controlling the environmental temperature (ambient temperature) of a secondary battery is well known. For example, Patent Document 1 listed below discloses a charging device that improves the discharge capacity by setting the ambient temperature to a predetermined temperature for charging. Further, in Patent Document 2 below, when the temperature of the battery body is too low during charging, unnecessary gas is generated from the electrolyte, so that the low temperature side temperature is controlled to a predetermined temperature or higher, and the temperature during charging is If the temperature is too high, the life is shortened. Therefore, a charging device is disclosed in which the high temperature side temperature is limited to a predetermined temperature or less for charging. Further, Patent Document 3 below discloses a charging device that prevents a reduction in capacity of the secondary battery by adjusting the ambient temperature of the secondary battery (for example, a lead storage battery) with a heating unit. Furthermore, Patent Document 4 below discloses a charging device that prevents deterioration of performance by adjusting the temperature of the secondary battery to a predetermined temperature range (0 ° C. to 40 ° C.). Also, in Patent Document 5 below, charging at a low temperature lowers the performance of the secondary battery, so charging at a predetermined temperature or higher, and charging at a high temperature shortens the service life to charge at a predetermined temperature or lower. And a charging device for charging by uniformly controlling the temperature between a plurality of battery cells constituting the battery pack.

  On the other hand, in Patent Document 6 below, in particular, in a charging device for a lithium battery mounted on an artificial satellite, freezing inside the nonaqueous electrolyte battery due to low temperature is prevented and stable charging is prevented by preventing battery deterioration due to high temperature. A charging device for exhibiting discharge characteristics is disclosed.

Japanese Patent Publication No. 7-87673 JP-A-8-185897 JP-A-8-223815 JP-A-11-55869 Japanese Patent Laid-Open No. 11-288744 JP 2001-155783 A

  Lithium secondary batteries are charged differently from nickel-hydrogen secondary batteries in order to maintain charge / discharge characteristics (reversibility) or long life due to the difference in properties from nickel-hydrogen secondary batteries. A method is needed. Even if the battery is charged at a constant current within a predetermined temperature range, the conventional charging method is insufficient because it shortens the time for rapid charging and improves the life of the lithium battery (charge / discharge cycle life). In particular, when charging a lithium battery, if the battery is charged at an environmental temperature lower than the appropriate temperature range for charging (for example, 15 ° C. to 35 ° C.), the self-heating temperature at the time of charging is low. It is necessary to charge while maintaining the charging current at a low current, and the conventional charging method is insufficient in reducing the charging time.

  Accordingly, an object of the present invention is to provide a lithium battery pack that shortens the charging time without reducing battery performance such as cycle life for a high-capacity lithium battery pack, and charging for a lithium battery for charging the lithium battery pack. To provide an apparatus.

  Another object of the present invention is to provide a charging device for a lithium battery that can be used without degrading the performance of the battery even when the environmental temperature or ambient temperature of the lithium battery pack or charging device is lower than the temperature range suitable for charging. There is.

  Still another object of the present invention is to provide a lithium battery pack that can be used without degrading battery performance even at a low ambient temperature where the work site where the cordless power tool is used includes a temperature range below freezing point. The object is to provide a charging device for a lithium battery.

  According to one aspect of the present invention, a battery pack of a lithium battery used as a power source for a cordless electric tool includes a plurality of lithium battery cells housed in a battery pack case, the battery pack housed in the case, A heater for adjusting the temperature of the lithium battery cell disposed in the vicinity of the plurality of lithium battery cells; and an electrode for supplying a current to the heater for adjusting the temperature.

  According to another aspect of the present invention, the case of the battery pack is provided with a vent hole for blowing air from outside the case to the temperature adjusting heater.

  According to still another aspect of the present invention, in a charging device for a lithium battery having an engaging portion for inserting a battery pack of a charged lithium battery, the battery pack of the charged lithium battery inserted into the engaging portion. A temperature adjustment mechanism is formed by a temperature adjustment heater housed in the case and a blower fan housed in the main body of the lithium battery charger, and the ambient temperature of the battery pack of the lithium battery to be charged is charged. When the temperature is lower than the optimum temperature range, the ambient temperature of the battery pack of the charged lithium battery is controlled by the temperature adjusting heater and the blower fan while the ambient temperature of the battery pack of the charged lithium battery is controlled. The battery is charged with a corresponding charging current value.

  According to still another aspect of the present invention, the engaging portion of the lithium battery charging device has a ventilation hole for supplying wind from the blower fan.

  According to another aspect of the invention, the battery pack is connected to an input power source and supplies a charging current to a battery pack of a lithium battery to be charged, and is electrically connected to the power supply unit. Charging current control means for supplying a predetermined charging current to the battery, a temperature detection sensor for detecting the ambient temperature of the battery pack, and the ambient temperature of the battery pack detected by the temperature detection sensor is lower than a chargeable temperature range Or, if it is high, the temperature adjustment means for adjusting the ambient temperature of the battery pack, and the power supply means, the charging current control means, and the temperature adjustment means are controlled from the start of charging to the stop of charging of the battery pack. A charging device including a control unit, wherein the temperature adjusting unit includes a heating unit formed in the battery pack, and a cooling unit formed outside the battery pack. The control means controls the temperature adjusting means so that the ambient temperature of the battery pack is in the chargeable temperature range, and when the ambient temperature of the battery pack is in the chargeable temperature range, The charging current control means is controlled so as to supply the charging current stepwise in accordance with the temperature range of the chargeable temperature range.

  According to another aspect of the present invention, the control means controls the charging current in a stepwise manner according to the temperature range of the chargeable temperature range, and the ambient temperature of the battery pack is a predetermined temperature in the chargeable temperature range. The temperature adjusting means is controlled so that

  According to still another feature of the present invention, the control means controls the temperature adjusting means so that the temperature rises to the chargeable temperature range when the ambient temperature of the battery pack is below the chargeable temperature range. To do.

  According to still another aspect of the present invention, the control means controls the temperature adjusting means so as to drop to the chargeable temperature range when the ambient temperature of the battery pack exceeds the chargeable temperature range. .

  According to still another aspect of the present invention, the control means is configured so that the ambient temperature is within the appropriate temperature range for charging even after the ambient temperature of the battery pack is within the chargeable temperature range and charging is started. The temperature adjusting means is controlled.

  According to still another aspect of the present invention, the chargeable temperature range is −15 ° C. to 55 ° C.

  According to still another aspect of the present invention, the appropriate charging temperature range is 15 ° C to 35 ° C.

  According to the lithium battery pack and the lithium battery charging device of the present invention, charging is performed by switching the charging current stepwise while controlling the charging current and the battery temperature based on the battery temperature of the battery pack of the lithium battery to be charged. Therefore, the charging time can be shortened, that is, rapid charging can be performed without significantly impairing the performance such as the life of the lithium battery pack.

  The above-described features and other features of the present invention as well as the above-described and other advantages will become more apparent from the following description of the present specification and the accompanying drawings.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 4. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments, and the repetitive description thereof is omitted.

[Configuration of charging device]
FIG. 1 shows a circuit diagram of a charging apparatus according to an embodiment of the present invention. In FIG. 1, a lithium battery pack 2 to be charged (hereinafter referred to as a battery pack) to be charged by a charging device 200 is a plurality of rechargeable lithium battery cells 2A (hereinafter referred to as battery cells) connected in series. And a temperature sensing element 2B functioning as a temperature detection sensor such as a thermistor disposed in contact with or in proximity to the battery cell 2A in order to detect the ambient temperature of the battery pack 2 (hereinafter referred to as battery temperature). Become. Furthermore, a temperature adjusting heater (heating means) 101 is accommodated in the battery pack 2 according to the present invention. The temperature adjusting heater 101 is connected to the external heater control circuit 102 and the constant voltage power supply 70 via the electrodes of the battery pack 2. The specific structure of the battery pack 2 is made of a synthetic resin battery case, as will be described later. For example, the battery pack 2 includes a battery cell 2A in which four lithium ion batteries (cells) having a nominal voltage of 3.6 V are connected in series, for a total of about 14.4. It has a voltage of V.

  The power supply means 201 for supplying a charging current to the battery pack 2 includes a first rectifying / smoothing circuit 10, a switching circuit 20, and a second rectifying / smoothing circuit 30.

  The first rectifying / smoothing circuit 10 includes a full-wave rectifying circuit 11 and a smoothing capacitor 12, and full-wave rectifies the AC power source 1 such as a commercial AC power source. The switching circuit 20 includes a high-frequency transformer 21, a MOSFET (switching element) 22 connected in series to a primary coil of the transformer 21, and a PWM control IC for modulating the pulse width of a drive pulse signal applied to the gate electrode of the MOSFET 22. (Drive signal control means) 23. The PWM control IC 23 controls the ON time of the MOSFET 22 by changing the drive pulse width supplied to the gate electrode of the MOSFET 22 based on the control input signal input from the charging current signal transmission means 5, and outputs the rectifying and smoothing circuit 30. The voltage and the charging current of the battery pack 2 are adjusted. The second rectifying / smoothing circuit 30 includes diodes 31 and 32 connected to the secondary coil side of the transformer 21, a choke coil 33, and a smoothing capacitor 34.

  A charging current control unit 60 and a constant voltage control unit 90 are electrically connected to the power supply unit 201 including the first rectifying / smoothing circuit 10, the switching circuit 20, and the second rectifying / smoothing circuit 30.

  Charging current control means 60 includes an operational amplifier circuit composed of operational amplifiers 61 and 62, input resistors 63 and 65, and feedback resistor 64. The input side of the charging current control means 60 is connected to the current detection means 3 comprising a resistor or the like for detecting the charging current of the battery pack 2. The output side is electrically connected to the PWM control IC 23 described above via the diode 130 and the charging current signal transmission means 5. Further, the charging current setting means 66 is connected to the inverting input terminal of the second stage operational amplifier 62. The charging current setting unit 66 sets the magnitude of the charging current in response to a control signal from an output port 51e of a microcomputer (control unit) 50 described later. That is, the voltage value applied to the inverting input terminal of the operational amplifier 62 is changed corresponding to the control signal from the output port 51e. Based on such a configuration, the charging current control means 60 controls the charging current supplied to the battery pack 2 according to the set value of the charging current setting means 66.

  The constant voltage control means 90 includes resistors 91 and 92 and an operational amplifier 93. The input side of the constant voltage control means 90 is connected to the positive side of the battery pack 2, and detects the charging voltage of the battery pack 2. Further, the voltage setting means 94 is connected to the inverting input terminal of the operational amplifier 93. Similarly to the charging current setting unit 66, the voltage setting unit 94 sets the magnitude of the charging voltage corresponding to a control signal from an output port 51e of the microcomputer 50 described later.

  In order to adjust the battery temperature of the battery pack 2 to a chargeable temperature range or an appropriate charging temperature range during charging, a temperature adjusting device 202 is provided in proximity to the battery pack 2 according to the present invention. The temperature adjusting device 202 includes a heater 101 that functions as a heating unit and a fan 6 that functions as a cooling unit. The heater 101 is connected to a heater control circuit 102 composed of, for example, an FET functioning as a resistance variable element for controlling a heating current flowing through the heater 101. The heater control circuit 102 receives a control signal from the output port 51d of the microcomputer 50, turns on or off the current flowing through the heater 102, and controls the magnitude of the current. The fan 6 serving as a cooling means includes a motor (not shown), and is controlled by a fan drive circuit 7 including a transistor 7a and bias resistors 7b and 7c. As will be described later, the fan drive circuit 7 is controlled by a control signal from the output port 51 b of the microcomputer 50.

  The operations of the power supply unit 201, the charging current control unit 60, the constant voltage control unit 90, the temperature adjustment device 202, and the like are controlled by the microcomputer 50. The microcomputer 50 is used as a central processing unit (CPU) 51 for executing a control program, a read only memory (ROM) 56 for storing a control program of the CPU 51, a work area of the CPU 51, a random data storage area, and the like. The microcomputer 50 includes an access memory (RAM) 53 and a timer 54. The microcomputer 50 further includes an A / D converter 52 for converting an analog input signal into a digital output signal, and an output port 51a for outputting a control signal. , 51b, 51c, 51d and 51e, and a reset input port 55 for inputting a reset signal when the power is turned on. These function blocks are connected to each other by an internal bus 58.

  A temperature detection signal from the temperature sensing element 2B that detects the battery temperature of the battery pack 2 is input to one input terminal of the A / D converter 52 via the battery temperature detection means 120 including the resistors 121 and 122.

  The voltage of the battery pack 2 is input to the other input terminal of the A / D converter 52 via the battery voltage detection circuit 40 including the voltage dividing resistors 41 and 42.

  A control signal for starting or stopping charging of the battery pack 2 is supplied from the output port 51c to the control input of the PWM control IC 23 via the charge control signal transmission means 4 according to the control program of the microcomputer 50. If a charge start control signal is received from the charge control signal transmission means 4, the MOSFET 22 starts a switching operation. Conversely, if a charge stop control signal is received, the MOSFET 22 stops a switching operation.

  Power supplies for the microcomputer 50, the charging current control means 60, the temperature adjustment device 202, the battery temperature detection means 120, and the like are supplied from a commercial AC power supply 1 by a constant voltage power supply 70 that forms a DC voltage source. The constant voltage power supply 70 includes a power transformer 71, a full-wave rectifier circuit 72, a constant voltage circuit including a transistor 73, a Zener diode 75, and a resistor 74, a three-terminal regulator 78, smoothing capacitors 77 and 79, and a reset. IC80. The reset IC 76 of the constant voltage power supply 70 has a function of outputting a reset signal to the reset input port 55 in order to put the microcomputer 50 in an initial state when the power is turned on.

  The monitor circuit 110 is charged when the operation state of the charging device responding to the battery temperature T of the battery pack 2 to be described later, that is, before the battery pack 2 is inserted, or when the battery temperature of the battery pack 2 is too low or too high. It is provided for displaying whether the battery is in a standby state, a state where charging is being performed, or a state where charging is completed. The monitor circuit 110 includes a light emitting diode (LED) array 111 as a display element, and the array 111 includes a red light emitting diode R and a green light emitting diode G. Further, resistors 112 and 113 are provided for limiting the currents of the light emitting diodes R and G, respectively. The lighting or blinking of the red light emitting diode R and the green light emitting diode G is controlled by the output of the output port 51a of the microcomputer 50 that controls the operation of the charging device. The red light-emitting diode R and the green light-emitting diode G are controlled so as to be turned on or blinking simultaneously in a certain state display, and display of “lit orange” or “flashing orange” is also performed.

[Structure of lithium battery pack and temperature control device]
FIG. 7 shows a partial cross-sectional structure diagram of the charging device 200 of the present invention and the battery pack 2 removably inserted (engaged) in the charging device 200. An engaging recess (engaging portion) 200B and an engaging projection (engaging portion) for inserting the lithium battery pack 2 to be charged into one end portion of the charging device 200 and electrically connecting to the circuit board of the charging device 200 ) 200C is provided. A fan 6 is mounted inside the engaging projection 200C, and a heater 101 is mounted in the battery pack 2 according to the present invention. As will be described later, the fan 6 and the heater 101 cooperate with each other to adjust the temperature. 202 is configured. The case portion of the engagement convex portion 200C is provided with a ventilation hole 200A for circulating the air blown by the fan 6 into the case of the battery pack 2.

  As shown in FIGS. 7 and 8, the battery pack 2 includes a synthetic resin case (housing) 2K, and a main body in which an engaging portion 2G to be inserted into the engaging recess 200B and a plurality of battery cells 2A are accommodated. Part 2H. The cross-sectional shape of the battery pack 2 is T-shaped. As shown in FIG. 8, the plurality of battery cells 2A are connected in series by metal pieces 2J. The temperature sensing element 2B that detects the battery temperature T of the battery pack 2 is disposed between the plurality of battery cells 2A. In addition, a circuit board 2D on which a circuit element 2F such as an FET is mounted is accommodated in the engaging portion 2G of the battery pack 2. The circuit board 2D may be provided with a protection circuit for preventing overdischarge or overcharge of the lithium battery. Further, according to the present invention, the circuit board 2D is adjacent to the battery cell 2A housed in the main body 2H. A temperature adjusting heater 101 is incorporated in the joint 2G or the main body 2H. As shown in FIG. 8, the battery pack 2, the temperature sensitive element 2 </ b> B, and the electrode 2 </ b> T serving as a terminal of the heater 101 are provided on both ends of the engaging portion 2 </ b> G. As shown in FIG. 8, when the engaging portion 2G of the battery pack 2 is inserted into the engaging recess 200B of the charging device 200, the hook 2E of the battery pack 2 is locked in the engaging recess 200B, and the battery pack 2 Fixed to charging device 200.

  Further, the lower case portion of the main body 2H of the battery pack 2 has a ventilation hole 2C communicating with the ventilation hole 200A as shown in FIG. The wind of the fan 6 is sent to the heater 101 in the battery pack 2 through the vent holes 200A and 2C. If the heater 101 is turned on (powered), hot air is blown to the outer peripheral surface of the battery cell 2A. . Conversely, if the heater is turned off, cold air is blown. Control of the fan 6 and the heater 101 will be described later.

[Operation of monitor circuit]
A display example of a light emitting diode (LED) by the monitor circuit 110 according to the charging device 200 of the present invention is shown in FIG. When the battery pack 2 is not inserted or electrically connected to the charging device 200 and “before battery insertion” is displayed, the green light-emitting diode G and the red light-emitting diode R are blinked simultaneously to “flash orange”. In addition, when the battery temperature T of the battery pack 2 is lower than the chargeable temperature range (T <−15 ° C.) and the battery is waiting for charging at a low temperature, the “low temperature standby” display blinks the red light emitting diode R. To “red flash”. Further, when the temperature of the battery pack 2 is within the chargeable temperature range (−15 ° C ≦ T <55 ° C.) and “charging”, the green light emitting diode G and the red light emitting diode R are turned on simultaneously. To “light up orange”. When the temperature of the battery pack 2 is higher than the rechargeable temperature range (55 ° C ≦ T) and the battery pack 2 is waiting for charging at a high temperature, the “high temperature standby” display blinks the green light emitting diode G " Further, the display of “end of charge” turns on only the green light emitting diode G and “lights green”. Thus, the monitor circuit 110 allows the user to grasp the operating state of the charging device.

[Charging operation mode]
Next, the charging mode by the charging device of the present invention will be described with reference to FIG. 3 and FIG. According to the charging device 200 of the present invention, the microcomputer 50 controls the charging current control means 60 and the temperature adjustment device 202 based on the battery temperature T of the battery pack 2 detected by the temperature sensing element 2B, and the battery An appropriate charging current corresponding to the temperature T is supplied, and the temperature of the battery pack 2 is adjusted. Hereinafter, the relationship between the battery temperature T of the battery pack 2 and the charging current, and the relationship between the battery temperature T and the temperature adjustment by the temperature adjustment device 202 will be described with reference to FIG.

  According to the present invention, the chargeable temperature range of the battery pack 2 is divided into a plurality of temperature sections. The limits on the low temperature side and the high temperature side of this chargeable temperature range are limited to temperatures that do not damage the battery life due to charging as much as possible. In the embodiment of the present invention, as shown in FIG. 3, the chargeable temperature range is limited to a range of (−15 ° C. ≦ T <55 ° C.).

  Further, the chargeable temperature range (−15 ° C. ≦ T <55 ° C.) is divided into a plurality of temperature sections according to the present invention. For example, as shown in FIG. 3, section B (−15 ° C ≦ T <0 ° C.), section C (0 ° C ≦ T <15 ° C.), section D (15 ° C ≦ T <35 ° C.). ) And section E (35 ° C ≦ T <55 ° C.). Corresponding to these four temperature categories, a charging current is set so as to minimize the deterioration of the battery life. In the embodiment shown in FIG. 3, charging currents of 1A, 4A, 9A, and 4A are set for the four temperature sections B, C, D, and E, respectively. The relationship between the temperature classification and the charging current is stored in the ROM 56 of the microcomputer 50. The microcomputer 50 outputs a control signal based on the temperature detected by the temperature sensing element 2B, and controls the charging current control means 60 so that the charging current according to the battery temperature T is supplied to the battery pack 2. This charging current tends to increase as it approaches the appropriate charging temperature range (section D shown in FIG. 4) including room temperature (25 ° C.). In the example shown in FIG. 3, the appropriate charging temperature range of the battery pack 2 for charging is a range of (15 ° C ≦ T <35 ° C) of the temperature category D, and at this time, the maximum charging current 9A is obtained. Is set. However, when the battery temperature T is within the upper limit of the chargeable temperature range and in the temperature segment E higher than the appropriate charging temperature range D, the current 4A is set to be lower than the maximum charging current 9A. This is because when the battery is charged at a temperature higher than the appropriate temperature range for charging and at a high current of 9 A, the battery temperature becomes high due to self-heating, and charging with a large current shortens the life of the lithium battery.

  According to the present invention, when the battery temperature T is lower than the chargeable temperature range (T <−15 ° C.), charging is not performed. Instead, the temperature adjustment device 202 composed of the heater 101 and the fan 6 is operated so that the battery temperature T falls within the chargeable temperature range. In this case, as shown in the temperature category A in FIG. 3, the heater 101 and the fan 6 are simultaneously turned on (operated) because they are on the lower temperature side than the chargeable temperature range (−15 ° C ≦ T <55 ° C.). Heat the battery pack strongly. When the battery temperature T rises to the chargeable temperature range, as described above, the charging current according to the temperature category is set and charging is started.

  According to the present invention, even if the battery temperature T rises to the low temperature side (for example, temperature category B) of the chargeable temperature range and charging starts, the operation of the temperature adjustment device 202 is not immediately turned off. This is because, in particular, lithium batteries have little self-heating during charging, and a temperature rise cannot be expected even after charging. For this reason, as shown in FIG. 3, in the temperature section B and the temperature section C on the low temperature side of the charging appropriate temperature range of the temperature section D, the battery pack 2 is operated by operating the heater 101 and the fan 6 of the temperature adjustment device 202. Heat. That is, according to the present invention, the temperature of the battery pack 2 is adjusted so that the battery temperature T is concentrated in the appropriate charging temperature range (temperature category D). Contrary to this, even when the battery temperature T is on the high temperature side (temperature section E and temperature section F) of the chargeable temperature range, the temperature adjusting device 202 is integrated into the appropriate charging temperature range (temperature section D). Thus, the temperature of the battery pack 2 is adjusted. In this case, as shown in the temperature section E and the temperature section F of FIG. 3, only the fan 6 is turned on to perform the cooling operation.

  Thus, according to the present invention, the control of the charging current and the temperature control of the battery pack 2 are simultaneously executed according to the battery temperature T of the battery pack 2. As a result, the charging system according to the present invention can be roughly classified into three charging modes as shown in FIGS. 4 (a), (b) and (c).

  First, in the first mode shown in FIG. 4A, charging is performed with a constant current. That is, in this mode, charging is started in the state of temperature section C or temperature section D, and a constant charging current is supplied until immediately before the end of charging. Note that the lithium battery has a characteristic that the charging current is reduced and the charging is terminated from the time when the charging voltage reaches the maximum.

  Next, the second mode shown in FIG. 4B is a mode in which the charging current is increased stepwise according to the temperature division. That is, when the battery temperature T of the battery pack 2 is inserted (engaged) into the charging device 200, the battery pack 2 is in the temperature section A of −15 ° C. or less and waits for charging. After heating to B, charging was started at 1A. Further, since the battery pack 2 hardly undergoes self-heating during charging, the battery temperature is heated to the temperature category C by the temperature adjusting device 202 while being charged, and at the same time, the charging current is switched to 4A for charging. Further, since the battery temperature T is in the appropriate temperature range (15 ° C ≦ T <35 ° C), which is the temperature category D, the optimum charging current is switched to 9A.

  Further, the third mode shown in FIG. 4C is a mode in which the charging current is decreased stepwise according to the temperature division. That is, since the battery temperature T was initially in the temperature suitable temperature range (15 ° C ≦ T <35 ° C) of the temperature category D, the charging was started at 9A. Since it rose, the charging current was switched to 4A.

[Charging operation flowchart]
Next, the charging operation by the charging device of the present invention will be described with reference to the operation flowcharts shown in FIGS.

  First, as shown in step S101 of FIG. 5, when the charging device 200 is turned on without the battery pack 2 inserted, the light emitting diodes R and G of the monitor circuit 110 flash simultaneously, and “orange flashing” is displayed. 2. As shown in FIG. 2, the state before the battery pack 2 is inserted is displayed.

  When the battery pack 2 is inserted and electrically connected in step S102, it is checked in step S103 whether or not the battery temperature T is in the above-described temperature category A (T <−15 ° C.). If the temperature is in temperature category A (when step S103 is No), the process proceeds to step S110 to step S112, and the monitor circuit 110 is “flashing red” and at the same time the heating intensity of the heater 101 is set to “strong”. And the fan 6 is turned on and the to-be-charged battery 2 is heated.

  In step S104, it is checked whether or not the battery temperature T of the battery pack 2 is in the above temperature category B (−15 ° C ≦ T <0 ° C.). When the battery temperature T is within the temperature category B, the process proceeds to step S113 to step S116, the monitor circuit 110 is "lit orange", and the heater 101 and the fan 6 of the temperature adjustment device 202 are turned on while charging current Is set to “1A” and charging is started. In this case, the heating intensity of the heater 101 is “medium”.

  In step S105, it is checked whether or not the battery temperature T of the battery pack 2 is in the above-described temperature category C (0 ° C ≦ T <15 ° C). When the battery temperature T is within the temperature category C, the process proceeds to step S117 to step S120, the monitor circuit 110 is “lit orange”, and the temperature adjustment device 202 is turned on, and the charging current is set to “4A”. And start charging. In this case, the heating intensity of the heater 101 is “weak”.

  In step S106, it is checked whether or not the battery temperature T of the battery pack 2 is in the above-described temperature category D (15 ° C ≦ T <35 ° C). When the battery temperature T is within the range of the temperature category D, the process proceeds to step S121 and step S122, the monitor circuit 110 is "lit orange", the charging current is set to "9A", and charging is started. In this case, since the temperature category D is the appropriate temperature range for charging, the temperature adjustment device 202 is not turned on.

  In step S107, it is checked whether or not the battery temperature T of the battery pack 2 is in the above-described temperature category E (35 ° C ≦ T <55 ° C). When the battery temperature T is within the temperature category E, the process proceeds to step S123 to step S125, the monitor circuit 110 is "lit orange", and only the fan 6 of the temperature adjustment device 202 is turned on, Set to 4A "and start charging. In this case, the heater 101 is turned off. When the battery temperature T is in the temperature category F (T ≦ 55 ° C.) in step S107, the process proceeds to step S108 and step S109, the monitor circuit 110 is “green blinking”, and the fan 6 of the temperature adjustment device 202 is operated. Is turned on, and the battery temperature T is waited for to drop.

  As shown in FIG. 6, after starting charging, the battery temperature T of the battery pack 2 is periodically checked. This check during charging is executed from the higher temperature section.

  First, in step S126, it is checked whether or not the battery temperature T of the battery pack 2 exceeds the appropriate charging temperature range (temperature category D), that is, whether or not (T ≧ 35 ° C.). When the battery temperature T exceeds the range of the temperature category D, the process proceeds to step S132 to step S134, and the charging current is switched to “4A” while only the fan 6 of the temperature adjustment device 202 is turned on.

  In step S127, it is checked whether or not the battery temperature T of the battery pack 2 is in the temperature category D (15 ° C ≦ T <35 ° C). When the battery temperature T is in the range of the temperature section D, the process proceeds to step S135 to step S137, the heater 101 and the fan 6 of the temperature adjustment device 202 are turned off, the charging current is switched to “9A”, and the charging is continued. In this case, since the temperature category D is the appropriate temperature range for charging, the temperature adjustment device 202 is not turned on.

  In step S128, it is checked whether or not the battery temperature T of the battery pack 2 is in the temperature category C (0 ° C ≦ T <15 ° C). When the battery temperature T is within the temperature category C, the process proceeds to step S129 to step S131, and the charging current is switched to “4A” while the temperature adjusting device 202 is turned on to continue charging. In this case, the heating intensity of the heater 101 is “weak”. In step S128, when the battery temperature T is in the temperature category B (−15 ° C ≦ T <0 ° C.), the process proceeds to step S138 to step S140, and the charging current is set to “1A while turning on the temperature adjustment device 202. To continue charging. In this case, the heating intensity of the heater 101 is “medium”.

  When the battery is nearly fully charged by the above charging, the charging current is reduced from the point where the charging voltage of the lithium battery 2 reaches the maximum, and the battery is fully charged. In step S141 in FIG. 6, it is checked whether or not the battery is fully charged. If it is determined that the battery is fully charged in step S141, the process proceeds to steps S142 to S154 and the charging is terminated. First, the monitor circuit 110 displays “green light” to indicate that charging is complete (step S142). After that, the temperature adjustment device 202 adjusts the temperature so that the battery temperature T is aggregated in the appropriate charging temperature range (15 ° C ≦ T <35 ° C) (steps S143 to S153). In step S154, it is checked whether or not the battery pack 2 has been removed from the charging apparatus 200. If the battery pack 2 has been removed (Yes in step S154), the process waits for the next charging.

  As will be apparent from the above description, according to the lithium battery pack of the present invention, since the temperature adjusting heater is provided in the lithium battery pack, rapid charging is possible during charging. Moreover, according to the charging device for lithium batteries of this invention, it can charge, controlling a charging current and battery temperature according to the battery temperature of a lithium battery pack, and can set the charge mode corresponding to battery temperature. In particular, since charging of a lithium battery has little self-heating effect, flowing a large charging current in charging in a low temperature region is not preferable from the viewpoint of battery characteristics such as life, but according to the present invention, the battery temperature is reduced. Since charging can be performed while controlling and switching the charging current, the charging time can be shortened without adversely affecting battery characteristics such as life. In particular, when using a cordless power tool at a work site in a low temperature area, if the lithium battery pack and the lithium battery charger of the present invention are carried together, the lithium battery pack can be rapidly charged while preventing deterioration of the battery characteristics. Thus, efficient work is possible.

[Examples of using lithium battery packs for cordless power tools]
FIG. 9 is a structural diagram showing an example in which the battery pack 2 of the present invention is applied to an impact driver 300. The impact driver 300 is attached to a drive unit 301 to which a power transmission unit including a motor 306 is mounted, a handle unit 302 to which the battery pack 2 is engaged, and a rotation output end that outputs a rotation impact force of the drive unit 301. Further, it is composed of a tip tool 304 such as a driver bit or a bolt tightening bit. A ventilation hole 305 is formed at the end of the drive unit 301, and outside air is sucked by a cooling fan 307 provided in the vicinity of the ventilation hole 305 to cool the drive unit 301. The heater 101 of the battery pack 2 is electrically connected to the control circuit 303 from the electrode terminal 2T of the battery pack 2 described above. The control circuit 303 includes a temperature switch such as a thermostat that responds to the ambient temperature, and heats the battery pack 2 by supplying current to the heater 101 only when the battery temperature of the battery pack 2 is a low temperature of 0 ° C. or lower. Control to do. In this control, the battery temperature of the battery pack 2 is adjusted to a temperature of 0 ° C. or higher before the impact driver 300 is overloaded. As a result, when the impact driver 300 is used in a work site in a low temperature region such as a cold region, the discharge efficiency and life of the battery pack 2 are deteriorated due to a rapid high-capacity discharge at a low temperature (large current consumption by motor drive). Can be prevented. In this way, the heater built in the battery pack can be applied to prevent deterioration of battery performance during discharging.

  Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. It is.

The circuit diagram which shows the Example of the charging device for lithium batteries which concerns on this invention. The characteristic view which shows operation | movement of the monitor circuit of the charging device for lithium batteries shown in FIG. The characteristic view which shows the charging operation by the charging device for lithium batteries shown in FIG. The characteristic view which shows the various charge modes by the charging device for lithium batteries shown in FIG. The flowchart which shows the charging operation by the charging device for lithium batteries shown in FIG. FIG. 6 is a flowchart showing steps subsequent to the flowchart shown in FIG. 5. FIG. The fragmentary sectional view which shows the structural example of the charging device for lithium batteries shown in FIG. The fragmentary sectional view of the lithium battery pack concerning the present invention. 1 is a structural diagram of a cordless power tool using a lithium battery pack according to the present invention.

Explanation of symbols

1: Input commercial power source 2: Lithium battery pack 2A: Battery cell 2B: Temperature sensing element 2C: Ventilation hole 2D: Circuit board 2E: Hook for fixing battery pack 2F: Circuit element 2G: Engagement part of battery pack 2H: Battery pack 2J: Metal piece 2T: Electrode (terminal) 3: Current detection means 4: Charging control signal transmission means 5: Charging current signal transmission means 6: Fan 7: Fan drive circuit 7a: Transistors 7b, 7c: Bias resistors 7d: wiring 10: first rectifying / smoothing circuit 11: full-wave rectifying circuit 12: smoothing capacitor 20: switching circuit 21: high-frequency transformer 22: MOSFET
23: PWM control IC 30: second rectifying / smoothing circuit 31, 32: rectifying diode 33: choke coil 34: smoothing capacitor 40: battery voltage detecting means 41, 42: voltage dividing resistor 50: microcomputer 51: central processing Device (CPU)
51a, 51b, 51c, 51d, 51e: output port 52: A / D converter 53: RAM 54: timer 55: reset input port 56: ROM
58: Internal bus (BUS) 60: Charging current control means 61, 62: Operational amplifiers 63, 65: Operational amplifier input resistance 64: Operational amplifier feedback resistance 66: Charging current setting means 70: Constant voltage power supply 71: Power transformer 72: Full-wave rectifier circuit 73: Regulator transistor 74: Resistor 75: Zener diode 78: Three-terminal regulator 77, 79: Smoothing capacitor 80: Reset IC
90: constant voltage control means 91, 92: voltage dividing resistor 93: operational amplifier 94: voltage setting means 101: heater 101a: heater wiring 102: heater control circuit 110: monitor circuit
111: Array of light emitting diodes 112, 113: Current limiting resistor G: Green light emitting diode R: Red light emitting diode 120: Temperature detecting means 121, 122: Voltage dividing resistor 200: Charging device 200A: Ventilation hole 200B: Engaging recess ( Engagement part)
200C: Engaging convex part (engaging part) 201: Power supply means 202: Temperature adjusting device 300: Impact driver 301: Driving part 302: Handle part 303: Control circuit 304: Tip tool 305: Ventilation hole 306: Motor 307: cooling fan

Claims (11)

  In a battery pack of a lithium battery used as a power source for a cordless electric tool, a plurality of lithium battery cells housed in a case of the battery pack, and housed in the case and disposed in proximity to the plurality of lithium battery cells A lithium battery battery pack, comprising: a temperature adjusting heater for the lithium battery cell, and an electrode for supplying a current to the temperature adjusting heater.   The battery pack for a lithium battery according to claim 1, wherein the battery pack case is provided with a ventilation hole for blowing air from the outside of the case to the temperature adjusting heater.   A charging device for a lithium battery having an engagement portion for inserting a battery pack of a lithium battery to be charged, the temperature adjustment being accommodated in a case of the battery pack of the lithium battery to be charged inserted into the engagement portion When a temperature adjustment mechanism is formed by a heater and a blower fan housed in the main body of the lithium battery charging device, and the ambient temperature of the battery pack of the lithium battery to be charged is in a lower temperature range than the appropriate temperature range for charging And charging with a charging current value corresponding to the ambient temperature of the battery pack of the rechargeable lithium battery while controlling the ambient temperature of the battery pack of the rechargeable lithium battery by the temperature adjusting heater and the blower fan. A charging device for a lithium battery.   The charging device for a lithium battery according to claim 3, wherein the engaging portion of the charging device for the lithium battery has a ventilation hole for supplying wind of the blower fan. A power supply means connected to the input power supply for supplying a charging current to the battery pack of the lithium battery to be charged;
A charge current control means electrically connected to the power supply means for supplying a predetermined charge current to the battery pack;
A temperature detection sensor for detecting an ambient temperature of the battery pack;
When the ambient temperature of the battery pack detected by the temperature detection sensor is lower or higher than the chargeable temperature range, temperature adjusting means for adjusting the ambient temperature of the battery pack;
A charging device comprising a control means for controlling the power supply means, the charging current control means, and the temperature adjustment means during the period from the start of charging to the stop of charging of the battery pack,
The temperature adjusting means comprises heating means formed in the battery pack, and cooling means formed outside the battery pack,
The control means controls the temperature adjusting means so that the ambient temperature of the battery pack falls within the chargeable temperature range, and when the ambient temperature of the battery pack is within the chargeable temperature range, the chargeable temperature A charging device for a lithium battery, wherein the charging current control means is controlled so as to supply a charging current in a stepwise manner according to a temperature range of the range.   The control means controls the charging current stepwise according to the temperature range of the chargeable temperature range, and controls the temperature adjusting means so that the ambient temperature of the charged lithium battery becomes a predetermined temperature in the chargeable temperature range. The charging device for a lithium battery according to claim 5, wherein the charging device is controlled.   The said control means controls the said temperature adjustment means so that it may rise to the said chargeable temperature range, when the ambient temperature of the said battery pack exists in the said chargeable temperature range or less. Item 7. A charging device for a lithium battery according to Item 6.   The said control means controls the said temperature adjustment means so that it may fall to the said chargeable temperature range, when the ambient temperature of the said battery pack exceeds the said chargeable temperature range. 7. The charging device for a lithium battery according to any one of 7 above.   The control means controls the temperature adjusting means so that the ambient temperature is within the appropriate temperature range for charging even after the ambient temperature of the battery pack is within a chargeable temperature range and charging is started. The charging device for a lithium battery according to any one of claims 5 to 8.   10. The charging device for a lithium battery according to claim 5, wherein the chargeable temperature range is −15 ° C. to 55 ° C. 10. The charging device for a lithium battery according to claim 9, wherein the appropriate temperature range for charging is 15 ° C to 35 ° C.

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