JP4578455B2 - Charger - Google Patents

Description

  The present invention relates to a charger, and more particularly to a charger that can effectively dissipate heat from a heat-generating component without using a dedicated heat radiation fin.

  The battery charger incorporates a heat generating component inside the case. The heat generating component is a power supply diode for rectification, a charge control FET for controlling charging, or the like. Furthermore, a charger incorporating a discharge resistor that completely discharges the battery in order to eliminate the memory effect of a nickel-hydrogen battery or a nickel cadmium battery has a large amount of heat generated by the discharge resistor. In particular, this discharge resistance increases the amount of heat generated when the time for discharging the battery is shortened. In other words, the amount of heat generated by the discharge resistor can be increased, the discharge time of the battery can be shortened, and the time required for refresh can be shortened.

  In order to shorten the time for completely discharging the battery, a charger provided with a plurality of discharge resistors has been developed (see Patent Document 1). The charger of this patent document can disperse the heat of the discharge resistor to increase the total calorific value and shorten the battery discharge time. However, since this charger is provided with a plurality of discharge resistors, there are disadvantages that the circuit configuration becomes complicated and the cost of components increases.

In addition, in order to effectively dissipate the heat generated by the heat generating component, a charger provided with heat dissipating fins has also been developed (see Patent Documents 2 and 3). In the chargers of Patent Documents 2 and 3, a heat sink is fixed to the case. This charger can efficiently dissipate the heat of the heat generating component with a heat sink fixed to the case. However, this charger has a drawback that it is more expensive than the charger of Patent Document 1. This is because the manufacturing cost for fixing the heat radiating plate to a specific position of the case is increased in addition to the cost of the heat radiating plate being higher than the discharge resistance.
JP 2005-184898 A Utility model registration No. 3027605 JP-A-6-343258

  The present invention has been developed for the purpose of solving this drawback. An important object of the present invention is to provide a charger that can effectively dissipate heat from a heat-generating component while reducing component cost and manufacturing cost.

The charger of the present invention has the following configuration in order to achieve the above-described object.
The charger has a case 1 having a mounting portion 2 in which a battery 11 to be charged is detachably mounted, and is provided in the mounting portion 2 of the case 1 and contacts an electrode of the battery 11 set in the mounting portion 2. And a circuit board 4 that fixes the metal terminal 3, and an electronic circuit that is mounted on the circuit board 4 and connected to the metal terminal 3 and has a heat generating component 5. Further, the charger is arranged by thermally coupling the heat generating component 5 to the metal terminal 3, conducting the heat of the heat generating component 5 to the metal terminal 3, and using the metal terminal 3 together with the heat radiation fin of the heat generating component 5. is doing.

  In the charger of the present invention, the heat generating component 5 can be the discharge resistors 10, 20, and 30 of the battery 11.

  The charger of the present invention has a power line conductive layer 6 in which a circuit board 4 is connected to a metal terminal 3 by soldering, and a heat generating component 5 is soldered to the power line conductive layer 6 to generate a heat generating component. 5 can be thermally coupled to the metal terminal 3 through the power line conductive layer 6.

  In the charger of the present invention, the heat generating component 5 can be thermally coupled to the metal terminal 3 through the heat conductive layer 21.

  The charger of the present invention has a power line conductive layer 36 in which the circuit board 4 is connected by soldering the metal terminals 3. The heating component 5 is connected to the power line conductive layer 36 via the heat conductive layer 31. The heat generating component 5 can be thermally coupled to the metal terminal 3 via the heat conductive layer 31 and the power line conductive layer 36.

  The charger of the present invention is characterized in that heat from the heat-generating component can be effectively dissipated while reducing the component cost and the manufacturing cost. This is because the charger of the present invention thermally couples the heat generating component to the metal terminal, conducts the heat of the heat generating component to the metal terminal, and uses the metal terminal together with the heat radiation fin of the heat generating component. As the metal terminal connected so as to be detachable from the battery, a metal terminal having a predetermined thickness is used so as to be elastically pressed against the electrode of the battery. The metal terminal is pressed against the electrode of the battery, and is reliably electrically connected while preventing poor contact. The metal terminal having this structure has a large heat radiation area and is excellent in heat conduction. For this reason, the heat of the heat-generating component disposed in thermal coupling with the metal terminal is efficiently conducted to the metal terminal and efficiently radiated like a radiation fin. In particular, since both sides of the metal terminal in contact with the battery are disposed in the air so as to be elastically deformable, the heat of the heat-generating component is efficiently radiated from both sides of the metal terminal.

  In particular, in the charger according to claim 2 of the present invention, the heat generating component is a discharge resistance of the battery, and the discharge resistance is thermally coupled to the metal terminal. This charger efficiently dissipates the heat generated by the discharge resistor, thereby reducing the temperature rise of the discharge resistor. This can increase the discharge current flowing through the discharge resistor without increasing the discharge resistance and without increasing the number of discharge resistors connected in parallel. For this reason, the memory effect can be eliminated by shortening the discharge time of the battery and refreshing the battery in a short time.

  In the charger according to claim 3 of the present invention, the power supply line conductive layer for soldering and connecting the metal terminals is provided on the circuit board, and the heat generating component is soldered to the power supply line conductive layer of the circuit board. The heat generating component is thermally coupled to the metal terminal through the power line conductive layer. The charger having this structure can be thermally coupled to a metal terminal by soldering a heat generating component to a circuit board. For this reason, it is possible to effectively dissipate the heat of the heat generating component by the metal terminal by connecting the heat generating component and the metal terminal in a thermally coupled state without fixing them with a special structure.

  In the charger according to claim 4 of the present invention, the heat generating component is thermally coupled to the metal terminal through contact with the heat conducting layer. This charger can be thermally coupled while insulating the heat-generating component and the metal terminal as an insulating layer on the heat conductive layer.

  Furthermore, the charger according to claim 5 of the present invention has a power line conductive layer in which a circuit board is connected by soldering metal terminals, and a heat generating component is connected to the power line conductive layer via a heat conductive layer. The heat generating component is thermally coupled to the metal terminal through the heat conductive layer and the power line conductive layer. This charger can also conduct heat of the heat generating component to the metal terminal efficiently while insulating the heat generating component and the metal terminal, and can dissipate heat.

  Embodiments of the present invention will be described below with reference to the drawings. However, the embodiment described below exemplifies a charger for embodying the technical idea of the present invention, and the present invention does not specify the charger as follows.

  Further, in this specification, in order to facilitate understanding of the scope of claims, numbers corresponding to the members shown in the examples are indicated in the “claims” and “means for solving problems” sections. It is added to the members. However, the members shown in the claims are not limited to the members in the embodiments.

  The charger shown in FIGS. 1 to 3 is provided in a case 1 having a mounting portion 2 in which a battery 11 to be charged is detachably mounted, and the mounting portion 2 of the case 1, and is set in the mounting portion 2. A metal terminal 3 that contacts the electrode of the battery 11, a circuit board 4 that fixes the metal terminal 3, and an electronic circuit that is mounted on the circuit board 4 and connected to the metal terminal 3, and has a heat generating component 5. With.

  The case 1 has a mounting portion 2 on the top surface for mounting so that the battery 11 can be detached. The mounting part 2 of the case 1 opens upward and detaches the battery 11 from above. Further, the charger shown in the figure is provided with a recess 12 in the central portion of the wall surface on one side (the lower side of the paper in FIG. 1) of the mounting portion 2 which is a rectangular concave shape in plan view. In this case 1, the battery in the mounting portion 2 can be easily removed by putting a hand in the recess 12. Since the battery charger shown in the figure is equipped with two batteries, the mounting portion 2 of the case 1 is provided with four metal terminals 3 including two plus terminals and two minus terminals. The plus terminal and the minus terminal are disposed at both ends of the mounting portion 2 and facing each other. The plus terminal is brought into contact with the plus electrode of the battery 11, and the minus terminal is brought into contact with the minus electrode of the battery 11 to charge the battery 11. Further, the case 1 has a terminal window 13 opened on the inner surface of the mounting portion 2 so that these metal terminals 3 protrude from the mounting portion 2. The charger shown in the figure has four terminal windows 13 opened so that the four metal terminals 3 protrude from the mounting portion 2. The metal terminal 3 fixed to the circuit board 4 disposed inside the case 1 protrudes from the terminal window 13 to the mounting portion 2 and is disposed at a fixed position.

  The metal terminal 3 is made of a metal plate that can be elastically deformed. The metal terminal 3 has a thickness of 0.2 mm to 0.5 mm so that the metal terminal 3 is pressed against the electrode 21 of the battery 11 with a predetermined pressure. The metal plate has a width of about 5 mm and a length of about 2 cm to 3 cm to increase the heat dissipation area. The width of the metal terminal 3 varies depending on the thickness of the metal plate. A thick metal plate narrows the width. Therefore, the metal terminal 3 can have a width of 3 mm to 1 cm in consideration of the thickness of the metal plate. Further, the metal terminal 3 can be elastically deformed flexibly by lengthening the metal plate. Therefore, the length of the metal terminal 3 is also designed to an optimum value depending on the width and thickness of the metal plate.

  The circuit board 4 has an electronic circuit mounted on an insulating board. The electronic circuit includes a charging circuit for the battery 11 and a refresh circuit for discharging the battery 11 to eliminate the memory effect. The refresh circuit includes the discharge resistance of the battery 11. As shown in the circuit diagram of FIG. 4, the refresh circuit 8 includes a discharge resistor 10 and a switching element 9. The refresh circuit 8 controls the switching element 9 to be turned on and discharges the battery 11 with the discharge resistor 10. The switching element 9 is controlled to be turned on / off by a control circuit (not shown). The control circuit switches on the switching element 9 when the battery 11 is refreshed. When it is detected that the battery 11 is completely discharged, the switching element 9 is switched from on to off, and the discharge of the battery 11 is stopped. Thereafter, the charging circuit charges the battery 11. When the battery 11 is fully charged, the charging circuit switches the switching element connected in series with the battery 11 from on to off and stops charging.

  The discharge resistor 10 is a heat-generating component 5 that is heated by Joule heat of the discharge current of the battery 11. The amount of heat generated by the discharge resistor 10 is proportional to the product of the electrical resistance and the square of the discharge current. Therefore, when the discharge current is increased in order to shorten the discharge time of the battery 11, the amount of heat generated by the discharge resistor 10 increases in proportion to the square of the current. If the discharge current is doubled to shorten the discharge time in half, the amount of heat generated by the discharge resistor 10 is quadrupled. Therefore, in order to shorten the time for completely discharging the battery 11 and shorten the refresh time, it is important how efficiently the discharge resistor 10 can dissipate heat.

  The discharge resistor 10 as the heat generating component 5 is fixed to the metal terminal 3 in a thermally coupled state. FIG. 3 shows a structure of a portion where the discharge resistor 10 of the heat generating component 5 is fixed to the circuit board 4 in a thermally coupled state. The circuit board 4 shown in this figure is provided with a power line conductive layer 6 to which the metal terminals 3 are connected by soldering. The circuit board 4 is provided with a power line conductive layer 6 connected to the metal terminal 3 and a signal line conductive layer 7 for transmitting a signal of an electronic circuit on the surface. The power line conductive layer 6 is larger in current than the signal line conductive layer 7 and wider than the signal line conductive layer 7. The wide power line conductive layer 6 is excellent in heat conduction. The discharge resistor 10 of the heat generating component 5 is fixed to the power line conductive layer 6 by soldering. In this structure, the discharge resistor 10 of the heat generating component 5 is fixed to the metal terminal 3 through the power line conductive layer 6 in a thermally coupled state. This structure thermally couples the discharge resistor 10 of the heat generating component 5 to the metal terminal 3 through the power line conductive layer 6 made of a wide metal layer. For this reason, the heat of the discharge resistor 10 of the heat generating component 5 is efficiently conducted to the metal terminal 3 through the power line conductive layer 6 and is radiated from the metal terminal 3. As shown in the circuit diagram of FIG. 4, a circuit configuration in which the discharge resistor 10 of the heat generating component 5 is directly connected to one electrode of the battery 11, in other words, a structure in which the discharge resistor 10 of the heat generating component 5 can be connected to the metal terminal 3. Can effectively conduct the heat of the discharge resistor 10 to the metal terminal 3.

However, in the charger of the present invention, as shown in the cross-sectional view of FIG. 5, the discharge resistor 20, which is the heat generating component 5, is brought into contact with the metal terminal 3 through the heat conductive layer 21 and thermally coupled and fixed. You can also. Further, as shown in the sectional view of FIG. 6, the discharge resistor 30, which is the heat generating component 5, is brought into contact with the power line conductive layer 36 provided on the circuit board 4 via the heat conductive layer 31, so that the heat generating component 5 is attached. It can also be thermally coupled to the metal terminal 3 via the heat conductive layer 31 and the power line conductive layer 36. The heat conductive layers 21 and 31 are insulating sheets such as mica and plastic sheets, or insulating resins such as silicon. As described above, the structure in which the heat generating component 5 is thermally coupled to the metal terminal 3 through the heat conductive layers 21 and 31 can thermally conduct heat efficiently by thermally coupling the heat generating component 5 and the metal terminal 3 in a wide area. Further, the structure in which the heat generating component 5 and the metal terminal 3 are insulated by the heat conductive layers 21 and 31 can efficiently radiate the heat generating component 5 as a circuit configuration in which the heat generating component 5 is not electrically connected to the metal terminal 3.
In FIG. 5, 26 indicates a power line conductive layer, 27 indicates a signal line conductive layer, and in FIG. 6, 37 indicates a signal line conductive layer.

Incidentally, FIG. 7 shows a charger having a heat-generating component as a heat radiation resistor, and the charger of the embodiment of the present invention (shown in the equivalent circuit of FIG. 8) and the conventional charger of the comparative example (equivalent circuit of FIG. 9). The heat dissipation characteristics shown in FIG. In this graph, the battery is discharged for a short time, and the temperature rise in the case due to the heat generated at this time is measured. In this measurement, as shown in FIGS. 8 and 9, the combined resistance R is discharged with two batteries 11 connected in series and 550 mA flows at 2.4 V, which is the output voltage of the two batteries 11. (About 4.36Ω) is used.
As shown in FIG. 9, in the comparative example, 10 resistors R0 (= 11Ω) are connected in parallel and in series, and are distributed and arranged on the printed circuit board located below the place where the battery 11 is mounted. Then, the temperature of the resistor R0 located at the center of the place where the battery 11 is mounted is measured and shown in FIG.
Further, as shown in FIG. 8, in the embodiment, two resistors R1 (= 2.4Ω) are connected in parallel, and eight resistors R2 (= 6.2Ω) are connected in parallel and in series. Furthermore, these resistors R1 and R2 are connected in series with each other. Further, two resistors R1 are thermally coupled to the output terminal as discharge resistors 10, and eight resistors R2 are distributed and arranged on a printed circuit board located below the location where the battery 11 is mounted. The temperature of the resistor R1 having the highest temperature is measured and shown in FIG.
As can be seen from FIG. 7, in the present invention, the temperature rise in the case can be reduced due to the excellent heat dissipation characteristics. This increases the discharge resistance, in other words, without using a large standard electrical resistance, and without increasing the number of discharge resistors connected in parallel, while reducing the manufacturing cost, and also the discharge resistance. This means that the temperature rise due to heat generation can be minimized.

It is a top view of the charger concerning one Example of this invention. It is sectional drawing which shows the state which set the battery to the charger shown in FIG. It is a cross-sectional perspective view which shows the internal structure of the charger shown in FIG. It is a circuit diagram of the refresh circuit of the charger concerning one Example of this invention. It is a principal part expanded sectional view of the charger concerning the other Example of this invention. It is a principal part expanded sectional view of the charger concerning the other Example of this invention. It is a graph which shows the thermal radiation characteristic of the charger of the Example of this invention, and the charger of the conventional comparative example. It is a circuit diagram which shows the equivalent circuit of the charger of the Example of this invention. It is a circuit diagram which shows the equivalent circuit of the charger of the conventional comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Case 2 ... Mounting part 3 ... Metal terminal 4 ... Circuit board 5 ... Heat-emitting component 6 ... Power supply line conductive layer 7 ... Signal line conductive layer 8 ... Refresh circuit 9 ... Switching element 10 ... Discharge resistor 11 ... Battery 12 ... Recess 13 ... Terminal window 20 ... Discharge resistor 21 ... Thermal conductive layer 26 ... Power line conductive layer 27 ... Signal line conductive layer 30 ... Discharge resistor 31 ... Thermal conductive layer 36 ... Power line conductive layer 37 ... Signal line conductive layer R ... Compound resistor R0 ... Resistance R1 ... Resistance R2 ... Resistance

Claims (5)

A case (1) having a mounting part (2) in which a battery (11) to be charged is detachably mounted, and a mounting part (2) of the case (1) are provided and set in the mounting part (2) A metal terminal (3) that contacts the electrode of the battery (11), a circuit board (4) that fixes the metal terminal (3), and a metal terminal (3) mounted on the circuit board (4). ) And an electronic circuit having a heat generating component (5),
The heat-generating component (5) is thermally coupled to the metal terminal (3), and the heat of the heat-generating component (5) is conducted to the metal terminal (3) to dissipate the metal terminal (3) to the heat-generating component (5). Charger used in combination with fins.   The charger according to claim 1, wherein the heat generating component (5) is a discharge resistor (10), (20), (30) of the battery (11).   The circuit board (4) has a power line conductive layer (6) formed by soldering and connecting the metal terminals (3), and the heat generating component (5) is soldered to the power line conductive layer (6). The charger according to claim 1, wherein the heat generating component (5) is thermally coupled to the metal terminal (3) through the power line conductive layer (6).   The charger according to claim 1, wherein the heat generating component (5) is in thermal contact with the metal terminal (3) through the heat conductive layer (21).   The circuit board (4) has a power line conductive layer (36) formed by soldering and connecting the metal terminals (3), the heat generating component (5) is connected to the power line conductive layer (36), and the heat conductive layer. The heat generating component (5) is thermally coupled to the metal terminal (3) via the heat conductive layer (31) and the power line conductive layer (36) in contact with each other via the (31). Charger.

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