WO2015075914A1

WO2015075914A1 - Charging device

Info

Publication number: WO2015075914A1
Application number: PCT/JP2014/005711
Authority: WO
Inventors: Takuya YOSHINARI; Toshio Mizoguchi; Masaki Namiki
Original assignee: Hitachi Koki Co., Ltd.
Priority date: 2013-11-25
Filing date: 2014-11-13
Publication date: 2015-05-28
Also published as: JP2015104216A

Abstract

A charging device (1) detachably receives a battery pack (100) formed with a first air vent hole (101a) for introducing air and a second air vent hole (101b) for discharging air, the charging device including a housing (2), a first fan (3), and a second fan (4). The housing is formed with a first wind vent hole (2a) configured to confront the first air vent hole and a second wind vent hole (2b) configured to confront the second air vent hole. The first fan is provided at the housing and is configured to send air to the first wind vent hole. The second fan is provided at the housing and is configured to draw air from the second wind vent hole.

Description

CHARGING DEVICE

The invention relates to a charging device, and more specifically to a charging device for charging a battery pack that is used as a power source for various equipment, tools (hereinafter referred to as "power tool").

At the time of charging a battery pack having lithium battery that is used as the power source of a cordless tool, if charging is performed with a large electric current, charging is done in a short period. However, the conventional battery pack has a problem that the battery pack generates a large amount of heat while being charged, thereby shortening the cycle life thereof.

Hence, in a proposed charging device, charging of a battery pack is performed while cooling the battery, thereby suppressing heat generation of the battery during charging process and charging the battery with a large current in a short period (Patent Literature 1).

PTL 1: Japanese Patent Application Publication No. 2003-143766.

However, if a charging current is increased by using a conventional cooling method, there is a problem that elevated temperatures within a battery pack cannot be suppressed sufficiently, that gas pressure within the battery rises, and that the cycle life of the battery is shortened.

It is an object of the invention to provide a charging device that cools a battery pack efficiently, thereby extending the cycle life of the battery pack.

In order to attain above and other object, the present invention provides a charging device configured to detachably receive a battery pack formed with a first air vent hole for introducing air and a second air vent hole for discharging air, the charging device including a housing, a first fan, and a second fan. The housing is formed with a first wind vent hole configured to confront the first air vent hole and a second wind vent hole configured to confront the second air vent hole. The first fan is provided at the housing and is configured to send air to the first wind vent hole. The second fan is provided at the housing and is configured to draw air from the second wind vent hole.

According to the charging device of this configuration, a plurality of fans having different roles cooperates to increase the amount (volume) and speed of cooling air, so that the battery pack is cooled efficiently and the life of the battery pack can be extended.

According to another aspect, the present invention provides a charging device configured to detachably receive a battery pack formed with a first air vent hole for introducing air and a second air vent hole for discharging air. The charging device includes a main body, a second fan, and a movable portion. The movable portion is movable relative to the main body, and is formed with a second wind vent hole configured to confront the second air vent hole. The second fan accommodated in the movable portion and configured to draw air from the second wind vent hole.

According to the charging device of this configuration, cooling air can pass through inside the battery pack regardless of the size of the battery pack. Thus, cooling process can be performed efficiently and the life of the battery pack can be prolonged.

According to another aspect, the present invention provides a charging device includes a housing, a first fan, and a second fan. The housing is configured to detachably receive a battery pack. The battery pack is formed with a first air vent hole and a second air vent hole. The housing has a first wind vent hole formed to confront the first air vent hole. The first fan is accommodated in the housing and is configured to send cooling air into the battery pack via the first air vent hole and the first wind vent hole. The second fan is accommodated in the housing and is configured to draw cooling air introduced in the battery pack by the first fan into the housing via the second air vent hole.

According to the charging device of this configuration, a plurality of fans having different roles cooperates to increase the amount (volume) and speed of cooling air, so that the battery pack is cooled efficiently and the life of the battery pack can be prolonged. Moreover, cooling air can pass through inside the battery pack regardless of the size of the battery pack, and thus cooling process can be performed efficiently and the life of the battery pack can be prolonged.

The present invention described above can provide a charging device that cools a battery pack efficiently, thereby extending the cycle life of the battery pack.

Fig. 1 is a side view that schematically shows a charging device and a battery pack charged by the charging device according to a first embodiment of the present invention. Fig. 2 is a top view that schematically shows the charging device according to the first embodiment. Fig. 3 is a partial cross-sectional view of the charging device and the battery pack charged by the charging device according to the first embodiment, taken along a line IV-IV in Fig. 2. Fig. 4 is a cross-sectional view showing interior of the battery pack according to the first embodiment. Fig. 5 is a side view that schematically shows the charging device and the battery pack charged by the charging device according to a first embodiment. Fig. 6 is a top view schematically shows the charging device according to the first embodiment. Fig. 7 is a block diagram of the charging device according to the first embodiment. Fig. 8 is a flowchart of controls of a charging device based on temperature of secondary batteries according to the first embodiment. Fig. 9 shows operating conditions of fans in the charging device based on temperature of the secondary batteries according to the first embodiment. Fig. 10 is a flowchart of controls of a charging device based on charging current forsecondary batteries according to a second embodiment. Fig. 11 shows operating conditions of fans in the charging device based on charging current for the secondary batteries according to the second embodiment.

Hereinafter, a first embodiment of the invention will be described while referring to Figs. 1 through 9.

A charging device 1 according to the first embodiment of the invention is a device for charging a battery pack 100. As shown in Figs. 1 and 2, the housing of the charging device 1 is a housing 2 made of heat-resistant resin material having electrical insulation property. The battery pack 100 can be mounted on or dismounted from the charging device 1. By sliding the battery pack 100 along a mounting direction A, the battery pack 100 is mounted on the charging device 1. The left-right direction in the drawing sheet of Fig. 1 is defined as the upper-lower direction of the charging device 1. Further, the upper-lower direction in the drawing of Fig. 1 sheet is defined as the front-rear direction of the charging device 1. The direction perpendicular to the drawing sheet of Fig. 1 is defined as the left-right direction of the charging device 1. The left-right direction in the drawing sheet of Fig. 4 is defined as the front-rear direction of the battery pack 100. Further, the upper-lower direction in the drawing sheet of Fig. 4 is defined as the upper-lower direction of the battery pack 100. The direction perpendicular to the drawing sheet of Fig. 4 is defined as the left-right direction of the battery pack 100.

The housing 2 includes a main body 9 and a movable portion 5. The main body 9 constitutes a lower part of the housing 2. The movable portion 5 is movable relative to the main body 9. A power cord 7 connectable to an AC power supply is provided on the front surface of the housing 2. A first wind vent hole 2a is formed in the upper surface of the main body 9 (Fig. 2). An outside-air inlet hole 2c is formed in the right surface of the main body 9 (Fig. 1). A main-body cooling air passage 6a connecting the outside-air inlet hole 2c and the first wind vent hole 2a is defined within the main body 9. A first fan 3 is disposed on the main-body cooling air passage 6a. Note that Fig. 2 shows a state in which the battery pack 100 is detached from a mount state in Fig. 1.

The movable portion 5 constituting a fan unit includes a supporting portion 5A and a protruding portion 5B. The supporting portion 5A confronts the upper surface of the main body 9 and supports the battery pack 100. The protruding portion 5B is located at the downstream position (rear position) of the supporting portion 5A in a mount direction A of the battery pack 100, and protrudes upward. The lower surface of the supporting portion 5A is slidable on the upper surface of the main body 9. The upper surface of the supporting portion 5A can contact the lower surface of the battery pack 100. The protruding portion 5B has a confronting surface 5C that can confront the rear surface of the battery pack 100. As shown in Fig. 3, a second wind vent hole 2b is formed on the confronting surface 5C.

As shown in Fig. 3, an exhaust hole 2d is formed on the rear surface of the protruding portion 5B at a rearward position of the second wind vent hole 2b. The second wind vent hole 2b and the exhaust hole 2d define a substantially linear-shaped movable-portion cooling air passage 6c that connects the second wind vent hole 2b and the exhaust hole 2d in the protruding portion 5B. A second fan 4 is disposed on the movable-portion cooling air passage 6c.

The supporting portion 5A has a coil spring 10 at the rear side of the supporting portion 5A and inside the main body 9. One end of the coil spring 10 is connected to the supporting portion 5A, and the other end is supported by the main body 9. The coil spring 10 urges the movable portion 5 in a direction opposite the mount direction A. The coil spring 10 serves as an urging member of the invention.

As shown in Fig. 4, the battery pack 100 mainly includes a battery pack case 101 and secondary batteries 102 accommodated within the battery pack case 101. As the secondary batteries 102, a rechargeable battery such as a lithium-ion battery is used.

The battery pack case 101 has substantially a rectangular-parallelepiped shape. The battery pack case 101 forms a first air vent hole 101a in the lower surface of the battery pack case 101, and forms a second air vent hole 101b in the rear surface of the battery pack case 101. The first air vent hole 101a is a hole for introducing cooling air to inside of the battery pack 100. The second air vent hole 101b is a hole for discharging cooling air that is introduced through the first air vent hole 101a to outside of the battery pack 100. The battery pack case 101A defines a battery-pack cooling air passage 6b connecting the first air vent hole 101a and the second air vent hole 101b therein. The secondary batteries 102 is disposed on the battery-pack cooling air passage 6b.

As shown in Figs. 1 through 3, when the battery pack 100 is mounted on the charging device 1, the battery pack 100 is moved on the supporting portion 5A of the movable portion 5 in the mount direction A. Since the battery pack 100 presses the confronting surface 5C, the movable portion 5 moves in the mount direction A against the urging force of the coil spring 10. When the battery pack 100 reaches a position where the first air vent hole 101a confronts the first wind vent hole 2a, mounting of the battery pack 100 on the charging device 1 is completed. Since the coil spring 10 urges the movable portion 5 in the direction opposite the mount direction A, the second air vent hole 101b formed in the battery pack 100 and the second wind vent hole 2b formed in the movable portion 5 keep a state in confrontation with each other.

In a state where the battery pack 100 is mounted on the charging device 1 as descried above, the first wind vent hole 2a confronts the first air vent hole 101a and, at the same time, the second air vent hole 101b confronts the second wind vent hole 2b. Since the air vent holes and wind vent holes confront each other, a cooling air passage 6 is formed to pass through the inside of the main body 9 and the inside of the battery pack 100 to reach the inside of the movable portion 5. That is, the cooling air passage 6 is formed by the battery-pack cooling air passage 6b that is a cooling air passage in the battery pack 100, and the main-body cooling air passage 6a and the movable-portion cooling air passage 6c that are cooling air passages in the housing 2 (housing cooling air passage).

Next, flow of cooling air in the charging device 1 and the battery pack 100 will be described. The first fan 3 introduces outside air, as cooling air, to the inside of the main body 9 via the outside-air inlet hole 2c. The introduced cooling air passes through the main-body cooling air passage 6a, and is sent to the battery pack 100 via the first wind vent hole 2a. That is, the first fan 3 discharges cooling air to the battery pack 100.

Cooling air sent toward the battery pack 100 flows from the first air vent hole 101a through the battery-pack cooling air passage 6b, and flows into the battery pack 100. The cooling air cools the secondary batteries 102, and is then drawn from the movable portion 5, and reaches the second wind vent hole 2b through the second air vent hole 101b.

Subsequently, cooling air flows to the inside of the movable portion 5 via the second wind vent hole 2b. Inside the movable portion 5, the second fan 4 sucks (draws) cooling air through the second wind vent hole 2b. In this way, cooling air passes from the inside of the housing 2 and through the cooling air passage 6, thereby cooling the secondary batteries 102 smoothly (without retention), and reaches the second fan 4. Eventually, cooling air is discharged to the outside of the housing 2 via the exhaust hole 2d. That is, the second fan 4 has a function of drawing cooling air from the battery pack 100.

In the present embodiment, the cooling air passage 6 can be formed even if the size of the battery pack varies. Fig. 5 shows a state in which a battery pack 106 having a smaller capacity and a shorter front-rear length than the battery pack 100 is mounted on the charging device 1. In this case, the movable portion 5 moves in the mount direction A depending on the size of the battery pack 106. Hence, a confrontation state of the second air vent hole 101b and the second wind vent hole 2b is kept, and the cooling air passage 6 is formed. Note that Fig. 6 shows a state in which a battery pack is not mounted on the charging device 1 (the movable portion 5).

In this way, since the confrontation state of the second air vent hole 101b and the second wind vent hole 2b is kept, the cooling air passage 6 can be formed between the battery pack 100 and the movable portion 5 or between the battery pack 106 and the movable portion 5. Thus, even if the battery packs with different sizes are mounted, cooling air is prevented from getting out of the housing 2. Hence, a certain amount of cooling air can pass through the inside of the battery pack 100 or the battery pack 106, and a highly-effective operation of the first fan 3 and the second fan 4 can be maintained. This suppresses a temperature increase of the secondary batteries 102 and the battery pack 100 or the battery pack 106, and high cooling efficiency can be obtained. As a result of that, product lives of the secondary batteries 102 and the

battery pack

100 or 106 can be extended. Note that, if an elastic body such as rubber is provided at one or the both of the second air vent hole 101b and the second wind vent hole 2b such that the elastic body surrounds these holes, higher cooling efficiency can be obtained. When the battery pack 100 is mounted on the movable portion 5, rubber contacts the other side to form a sealed structure. This suppresses cooling air from getting out from the connection portion between the battery pack 100 and the movable portion 5.

If two fans are provided, the amount of cooling air increases and cooling efficiency increases, compared with a case in which a single fan is used. Especially, in the present embodiment, the first fan 3 is disposed at the upstream position of the

battery pack

100 or 106 in a direction in which cooling air flows along the cooling air passage 6, and the second fan 4 is disposed at the downstream position of the

battery pack

100 or 106 for drawing cooling air within the

battery pack

100 or 106. This configuration stabilizes the cooling air passage 6, and prevents generation of turbulence within the

battery pack

100 or 106 and prevents deviation of cooling air from air passage 6. This suppresses a temperature increase of the secondary batteries 102 and the

battery pack

100 or 106, and a increased cooling effect can be obtained. This results in longer product lives of the secondary batteries 102 and the

battery pack

100 or 106.

Fig. 7 shows a block diagram of the charging device 1 according to the first embodiment. The charging device 1 mainly includes a rectifier circuit 201, a main power supply 204, a power supply 203, a power supply 212, a regulator 214, an auxiliary power source 202, a microcomputer 215 and a charging state display 213. In Fig. 7, the charging device 1 charges the secondary batteries 102 disposed within the battery pack 100, in a state where the charging device 1 is connected to the AC power supply 200. These circuits are provided within the housing 2 (the main body 9 and the movable portion 5).

The rectifier circuit 201 rectifies current obtained from the AC power supply 200, and outputs the current to the main power supply 204 and the auxiliary power source 202 as DC current. The main power supply 204 includes a switching element 204a and an FET 204b. The FET 204b performs switching and changes a DC output from the rectifier circuit 201 to a voltage of pulse train waveform. The voltage of pulse train waveform is applied to a primary coil of a transformer 205, is stepped up (or stepped down) by the transformer 205, and is outputted to the rectifier circuit 206. The rectifier circuit 206 is configured to rectify and smooth an output voltage obtained from a secondary coil of the transformer 205 to generate and output a DC voltage.

The auxiliary power source 202 is connected to the rectifier circuit 201 and is supplied with power. The auxiliary power source 202 supplies the switching element 204a with a power-supply voltage via the power supply 203. The auxiliary power source 202 supplies the microcomputer 215 with a stabilized power-supply voltage via the power supply 212 and the regulator 214.

The voltage and current outputted from the rectifier circuit 206 is subject to controls of voltage and current performed by a feedback circuit 208, and is outputted to the secondary batteries 102 via a positive terminal 211a and a negative terminal 211b.

The battery pack 100 has a positive terminal 111a and a negative terminal 111b for charging, which are respectively connected to the positive terminal 211a and the negative terminal 211b at the charging device 1, when the battery pack 100 is mounted. The battery pack 100 mainly includes therein a battery-type determining element 103, a thermistor 104 which is a thermosensor, and a protection IC 105, which are electrically connected to respective circuits of the charging device 1 when the battery pack 100 is mounted. The battery-type determining element 103 and the thermistor 104 output a type and temperature of the secondary batteries 102 to the microcomputer 215 as electrical signals. The protection IC 105 outputs an electrical signal depending on a state of the secondary batteries 102. As an example, the protection IC 105 outputs a high signal when the secondary batteries 102 is a normal operating voltage which is not overcurrent, over discharge, or overcharge. The protection IC 105 outputs a low signal when the secondary batteries 102 is other than a normal state, such as when overcurrent, over discharge, or overcharge is to be notified. In addition to the above-mentioned electrical signals, the microcomputer 215 reads charging current via a current detector 210. The microcomputer 215 is an example of a control circuit of the invention.

In the first embodiment, the microcomputer 215 controls rotational speeds of the first fan 3 and the second fan 4 based on temperature of the secondary batteries 102 outputted from the thermistor 104. For example, only the second fan 4 is activated when charging is started, and the first fan 3 is also activated when the secondary batteries 102 reaches a predetermined temperature.

Fig. 8 shows a flowchart of controls based on temperature of the secondary batteries 102 according to the first embodiment. Further, Fig. 9 shows operating conditions of the fans based on temperature of the secondary batteries 102 according to the first embodiment. The process of the flowchart is started with S300 when the power cord 7 is connected to an external power supply and power is supplied to the microcomputer 215. In an initial state, the first fan 3 and the second fan 4 are both stopped (S301). In S302, the microcomputer 215 determines whether the battery pack 100 is mounted and what the type of the battery pack 100 (rated voltage etc.) is, based on a signal from the battery-type determining element 103. If the battery pack 100 is mounted (S302: Yes), the process advances to S303 and thereafter. If the battery pack 100 is not mounted (S302: No), the process returns to S301.

In S303 through S309, the microcomputer 215 performs controls of rotational speeds (the rotational frequency) of the first fan 3 and the second fan 4 based on temperature of the secondary batteries 102. The microcomputer 215 controls the first fan 3 and the second fan 4 by using preset temperature thresholds Ta, Tb and Tc as criteria for judgment. In the present embodiment, as the temperature of the secondary batteries 102 increases, the number of operating fans or the rotational speed of the fan is increased in a stepwise manner, so as to increase the amount of cooling air. When the temperature of the secondary batteries 102 is lower than Ta (S303: Yes), only the second fan 4 is operated at low rotational speed (S306). When the temperature of the secondary batteries 102 is higher than or equal to Ta and lower than Tb (S303: No, S304: Yes), the first fan 3 and the second fan 4 are operated at low rotational speed (S307). When the temperature of the secondary batteries 102 is higher than or equal to Tb and lower than Tc (S304: No, S305: Yes), the first fan 3 and the second fan 4 are operated at medium rotational speed (S308). When the temperature of the secondary batteries 102 is higher than or equal to Tc (S305: No), the first fan 3 and the second fan 4 are operated at high rotational speed (S309).

In S310, the microcomputer 215 checks a charge state of the battery pack 100 based on an electrical signal from the current detector 210. If the secondary batteries 102 is a lithium battery, the secondary batteries 102 is generally charged by a constant-current and constant-voltage changing method. Charging is performed with a predetermined charging current and, when the battery voltage reaches a constant voltage value (for example, 4.2V/cell multiplied by the number of cells), charging current is gradually decreased in a state where the charging voltage is kept at the constant voltage value. When the charging current reaches a full charge current value, the charging state is determined to be full charge and charging is finished. Accordingly, if the signal from the current detector 210 indicates the full charge current value and the battery pack 100 is in a full charge state (S310: Yes), only the second fan 4 is rotated at low rotational speed in S311. If the battery pack 100 is not in a full charge state (S310: No), the process returns to S302 again to determine the mount state of the battery pack 100. If the battery pack 100 is dismounted from the charging device 1 (S312: No), all the fans are stopped in S313. In this way, the microcomputer 215 controls the rotational speeds of the first fan 3 and the second fan 4 on the basis of the temperature of the secondary batteries 102. Since the both fans are stopped before and after the battery pack is connected, power consumption can be reduced at a charging standby time.

Next, a second embodiment will be described while referring to Figs. 10 and 11. In the second embodiment, the microcomputer 215 controls the first fan 3 and the second fan 4 on the basis of detected charging current. For example, only the second fan 4 is activated when the charging current is small, and the first fan 3 is also activated when the charging current exceeds a certain value.

Fig. 10 shows a flowchart of controls based on charging current according to the second embodiment. Further, Fig. 11 shows operating conditions of the fans based on charging current for the secondary batteries 102 according to the second embodiment. Since the steps other than S403, S404, and S405 are the same as those in the first embodiment, duplicating descriptions are omitted. In S403 through S405, the microcomputer 215 controls the second fan 4 and the first fan 3 by using preset current thresholds Ia, Ib, and Ic of the charging current as criteria for judgment. Here, as indicated in the first embodiment, a lithium battery is generally charged by the constant-current and constant-voltage changing method. There is a case where the charging current under a constant-current control is changed in a stepwise manner, due to a reason for shortening a charging period, or other reasons. Specifically, charging is started with a charging current Ic at an initial charging period. When the charging voltage (battery voltage) reaches a constant voltage value, the charging current is switched to a charging current Ib (<Ic). The battery voltage decreases at that time but increases again and, when the battery voltage again reaches a constant voltage value, the charging current is switched to a charging current Ia (<Ib). Subsequently, when the battery voltage again reaches the constant voltage value, the charging is switched to constant-voltage charging. When the charging current reaches a full-charge current value, charging is finished. In the second embodiment, if the charging current increases, the number of operating fans or the rotational speed of the fan is increased in a stepwise manner, so as to increase the amount of cooling air. In other words, in an initial charging period, heat generation of the second battery becomes so large that the amount of cooling air is increased in the initial charging period, and the amount of cooling air is reduced as charging proceeds. In the initial charging period, the charging current is large. Thus, if the charging current is larger than or equal to Ic (S405: No), the first fan 3 and the second fan 4 are operated at high rotational speed. In this case, there are three current thresholds, and it is assumed that the charging current in a constant current period is switched four times or more. If the charging current is larger than or equal to Ib and smaller than Ic (S404: No, S405: Yes), the first fan 3 and the second fan 4 are operated at medium rotational speed (S308). If the charging current is larger than or equal to Ia and smaller than Ib (S403: No, S404: Yes), the first fan 3 and the second fan 4 are operated at low rotational speed (S307). If the charging current is smaller than Ia (S403: Yes), only the second fan 4 is operated at low rotational speed (S306). That is, this control is performed in a later charging period and a constant-voltage charging period.

As described above, the amount of cooling air is controlled appropriately based on the temperature or charging current of the secondary batteries 102. This control method prevents the inside of the secondary batteries 102 from generating high temperatures, and also realizes highly effective charging suitable for the state of the secondary batteries 102, thereby obtaining an effect of longer product lives of the secondary batteries 102 and the

battery pack

100 or 106.

According to the charging device 1 in the embodiments, cooling air can pass through inside the

battery pack

100 or 106 regardless of the size of the

battery pack

100 or 106. Thus, cooling process can be performed efficiently and the life of the

battery pack

100 or 106 can be prolonged.

According to the charging device 1 in the above embodiments, cooling air can be obtained so that the cooling air smoothly passes through a main-body cooling air passage 6a, a battery-pack cooling air passage 6b, and a movable-portion cooling air passage 6c. Thus, cooling efficiency of the

battery pack

100 or 106 increases, and the life of the

battery pack

100 or 106 can be extended.

According to the charging device 1 in the above embodiments, a confrontation state between a second wind vent hole 2b and a second air vent hole 101b can be maintained by an urging member. Because cooling of the

battery pack

100 or 106 can be maintained continuously, the life of the

battery pack

100 or 106 can be prolonged.

According to the charging device 1 in the above embodiments, by making the amount of cooling air variable depending on charging current or temperature in the

battery pack

100 or 106, cooling efficiency of the

battery pack

100 or 106 can be increased. Hence, the life of the

battery pack

100 or 106 can be extended.

According to the charging device 1 in the above embodiments, a cooling function can be operated only when the

battery pack

100 or 106 is mounted, so that energy for cooling process can be saved. That is, the

battery pack

100 or 106 can be cooled with saved energy, and the life of the

battery pack

100 or 106 can be prolonged.

While the present invention has been described in detail with reference to the embodiments thereof, it would be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention.

For example, in the present embodiment, three thresholds are used as the criteria for judgment in the control. However, thresholds larger than or smaller than three may be used for controlling. The number of fan may be one, that is, a fan may be provided only at the movable portion. Further, the number of fans may be three or more, and controls may be performed for each of the fans. The method for controlling cooling air is not limited to the one using operation states of fans and rotational speed. For example, the amount of cooling air may be adjusted by controlling the angle of rotary blades of fans. In the drawings of the present embodiment, axial fans having propellers are illustrated. However, for example, other types of fans such as a sirocco fan and a centrifugal fan may be used. The microcomputer 215 may perform controls based on both values of the temperature and charging current of the second battery. For example, for each fan, the microcomputer 215 may adopt a larger one of the rotational speed obtained from the flowchart of Fig. 8 and the rotational speed obtained from the flowchart of Fig. 10. The temperature used as criteria for the control is not limited to the temperature of the secondary batteries 102. For example, temperature of cooling air, circuits, or other parts within the battery pack 100 may be measured, and each fan may be controlled based on the temperature.

1: charging device, 2: housing, 3: first fan, 4: second fan, 5: movable portion, 6: cooling air passage, 9: main body, 100: battery pack, 2a: first wind vent hole, 101a: first air vent hole, 101b: second air vent hole, 2b: second wind vent hole, 104: thermistor, 215: microcomputer

Claims

A charging device configured to detachably receive a battery pack formed with a first air vent hole for introducing air and a second air vent hole for discharging air, characterized in that the charging device comprises:
a housing formed with:
a first wind vent hole configured to confront the first air vent hole; and
a second wind vent hole configured to confront the second air vent hole;
a first fan provided at the housing and configured to send air to the first wind vent hole; and
a second fan provided at the housing and configured to draw air from the second wind vent hole.
The charging device according to claim 1, wherein the housing is formed with an exhaust hole for discharging air drawn by the second fan to outside of the housing.
The charging device according to claim 1, wherein the housing is configured to detachably receive a plurality of sizes of battery packs; and
wherein the housing comprises:
a main body; and
a movable portion movable relative to the main body depending on a size of the battery pack.
The charging device according to claim 3, wherein the movable portion is formed with the second wind vent hole and the exhaust hole, and defines a movable-portion cooling air passage whose one end is at the second wind vent hole and another end is at the exhaust hole;
wherein the battery pack defines a battery-pack cooling air passage whose one end is at the first air vent hole and another end is at the second air vent hole;
wherein the main body is formed with an outside-air inlet hole, and defines a main-body cooling air passage whose one end is at the outside-air inlet hole and another end is at the first wind inlet hole, and
wherein the first fan is disposed on the main-body cooling air passage, and the second fan is disposed on the movable-portion cooling air passage.
The charging device according to claim 3, further comprising an urging member that urges the movable portion in a direction from the second wind vent hole toward the second air vent hole.
The charging device according to claim 2, further comprising a control circuit accommodated in the housing and configured to detect a charging current for the battery pack, the control circuit controlling the first fan and the second fan on a basis of the charging current.
The charging device according to claim 2, further comprising a control circuit accommodated in the housing and configured to detect temperature within the battery pack, the control circuit controlling the first fan and the second fan on a basis of the temperature within the battery pack.
The charging device according to claim 6, wherein, when the battery pack is mounted, the control circuit activates at least one of the first fan and the second fan.
The charging device according to claim 6, wherein the control circuit stops operation of, in response to detachment of the battery pack from the charging device, one of the first fan and the second fan if the one of the first fan and the second fan has been operating and remaining one of the first fan and the second fan has been stopped, and stops operation of, in response to detachment of the battery pack from the charging device, the first fan and the second fan if the first fan and the second fan have been operating.
A charging device configured to detachably receive a battery pack formed with a first air vent hole for introducing air and a second air vent hole for discharging air, the charging device comprising:
a main body,
characterized in that the charging device further comprises:
a movable portion that is movable relative to the main body, the movable portion formed with a second wind vent hole configured to confront the second air vent hole; and
a second fan accommodated in the movable portion and configured to draw air from the second wind vent hole.
The charging device according to claim 10, wherein the battery pack defines a battery-pack cooling air passage whose one end is at the first air vent hole and another end is at the second air vent hole;
wherein the main body is formed with a main-body cooling air passage whose one end is at a first wind vent hole configured to confront the first air vent hole; and
wherein the charging device further comprises a first fan disposed on the main-body cooling air passage and configured to introduce cooling air into the main body.
The charging device according to claim 11, further comprising an urging member that urges the movable portion in a direction from the second wind vent hole toward the second air vent hole.
A charging device comprising:
a housing configured to detachably receive a battery pack formed with a first air vent hole and a second air vent hole,
characterized in that:
the housing has a first wind vent hole formed to confront the first air vent hole; and
the charging device further comprises:
a first fan accommodated in the housing and configured to send cooling air into the battery pack via the first air vent hole and the first wind vent hole; and
a second fan accommodated in the housing and configured to draw cooling air introduced in the battery pack by the first fan into the housing via the second air vent hole.
The charging device according to claim 13, wherein the housing is formed with an exhaust hole for discharging cooling air that is drawn into the housing by the second fan to outside of the housing.
The charging device according to claim 1, wherein the housing comprises:
a main body; and
a movable portion that is movable relative to the main body depending on a size of the battery pack, the second fan being provided at the movable portion.