JP3900227B2 - battery pack - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a chargeable / dischargeable battery pack used for portable electronic devices such as mobile phones, notebook computers, camcorders, and CD players.
[0002]
[Prior art]
The secondary battery of the battery pack has a high operating voltage, a high energy density, a large output current, a long cycle life, no memory effect, and a short charge time. Lithium ion batteries are frequently used.
[0003]
A lithium ion battery may generate heat and burst or ignite when short-circuited. Further, when charged with an overcurrent, the battery temperature rises abnormally and the battery life is shortened. Furthermore, the battery life is shortened by overcharge, overdischarge and the like. In order to prevent such inconvenience, a charge / discharge control circuit is provided in a battery pack using a lithium ion battery. The charge / discharge control circuit includes a monitoring circuit that measures and controls battery temperature, battery current, battery voltage, and the like, and a switching circuit that stops charging or discharging by the monitoring circuit.
[0004]
Japanese Patent Application Laid-Open No. 7-50157 discloses a battery pack in which a battery unit in a form in which a plurality of secondary batteries are fixed in parallel on a circuit board having a charge / discharge control circuit is housed in the case. . In this battery unit, an electrode of a secondary battery is spot welded to a connection plate soldered to a circuit pattern, and the battery is fixed on the substrate.
[0005]
[Problems to be solved by the invention]
Since the secondary battery is attached to the circuit board through a thin connection plate, the battery may move in the case due to vibration or impact during transportation or the like, and the connection plate may be damaged. In order to prevent the batteries from contacting each other, Japanese Patent Application No. 5-290821, etc. describes a battery with a partition plate for insulating the batteries, but prevents the movement of the batteries in the axial direction. Can not do it.
[0006]
Furthermore, since the thickness of the case is reduced in order to reduce the size and weight of the battery pack, there is a problem that the strength of the case is weak. Further, since the lithium ion battery directly hits the inner surface of the case, when the battery pack is accidentally dropped, the impact may be directly transmitted to the lithium ion battery and the performance may be deteriorated.
[0007]
In addition, when a battery is mounted on a circuit board, an arrangement space for electronic components constituting the charge / discharge control circuit is required in addition to the arrangement space for the battery. Therefore, if the electronic components are not properly arranged, the battery pack becomes large. There is a problem of becoming.
[0008]
The present invention has been made in order to solve the above problems, and an object of the present invention is to provide a battery pack that can reinforce the case while fixing the secondary battery so as not to move in the case. .
[0009]
It is another object of the present invention to provide a battery pack that can appropriately arrange electronic components on a circuit board.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, in the battery pack of the present invention, a circuit board on which a plurality of cylindrical secondary batteries and a charge / discharge control circuit for controlling the charge / discharge are mounted is incorporated in a plastic case. In the battery pack, the battery is integrally provided on the inner wall of the case, and regulates the movement of the plurality of secondary batteries in the axial direction and the radial direction at positions where the plurality of secondary batteries are separated from each other by a predetermined distance. A plurality of ribs forming a movement restricting portion are provided.
[0011]
In the battery pack according to claim 2, the battery movement restricting portion is a concave receiving portion into which a part of the outer periphery of the secondary battery is fitted. In the battery pack according to claim 3, the battery movement restricting portion is one end of a rib, and the one end is in contact with an edge of the secondary battery on the electrode side so as not to move in the axial direction.
[0012]
In the battery pack according to claim 4, an opening is provided in the circuit board, and a part of the electronic components constituting the charge / discharge control circuit is disposed in the opening. In the battery pack according to claim 5, a part of the electronic components constituting the charge / discharge control circuit is disposed in a gap between two secondary batteries attached in parallel to the circuit board. is there.
[0013]
According to a sixth aspect of the present invention, a ground terminal for connecting the ground of the circuit board to the chassis ground of an electronic device to be externally connected is exposed outside the case.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIG. 1, the battery pack 10 has a battery unit 20 housed in a rectangular case composed of a case lid 11 and a case body 12. The battery unit 20 includes a circuit board 19 constituting a charge / discharge control circuit and lithium ion batteries 13 to 18.
[0015]
The circuit board 19 is provided with a connector 24 that fits into an opening 22 provided in the case body 12. The connector 24 is provided with a plus terminal, a minus terminal, and a connection detection terminal. The plus terminal and the minus terminal are for charging / discharging with the electronic apparatus. The connection detection terminal is used to detect whether or not the battery pack 10 is normally loaded in the electronic device or the charger.
[0016]
Each of the lithium ion batteries 13 to 18 has a cylindrical shape, and each electrode is spot-welded to the conductive battery connection plate 26. One end of the battery connection plate 26 is soldered to the wiring pattern of the circuit board 19. Accordingly, the lithium ion batteries 13 to 18 are fixed to the circuit board 19 via the battery connection plate 26. The six batteries 13 to 18 are divided into two sets of three, and the two sets are arranged on the circuit board 19 in an L shape so that the axial directions intersect.
[0017]
The substrate 19 is inserted into the case body 12 with the batteries 13 to 18 facing downward. The case body 12 is formed of an insulating plastic material, and reinforcing ribs 28 and 29 are formed in a lattice shape on the inner wall of the bottom surface to prevent warping of the bottom surface and reinforcing the strength. In order to fix the batteries 13 to 18 using the reinforcing ribs 28 and 29, as shown in FIGS. 2 and 3, an arcuate receiving portion 27 that receives a part of the outer periphery of each of the batteries 13 to 18 from below. Is formed on the reinforcing rib 28. The receiving part 27 is used as a battery movement restricting part that prevents lateral (radial) movement.
[0018]
The pair of reinforcing ribs 28 are provided so as to extend in the diametrical direction of the battery so as to receive two axial ends of the batteries 13 to 18. The receiving portions 27 of these reinforcing ribs 28 hold the batteries 13 to 18 so as not to contact the inner surface of the case main body 12 so that impact due to dropping or vibration during transportation is not directly applied to the batteries 13 to 18. Absorb. Moreover, the receiving part 27 is provided at a predetermined interval so that the batteries do not adhere to each other, and when one battery generates heat, heat is not transmitted to the other battery. The shape of the receiving portion 27 may be V-shaped or rectangular.
[0019]
The reinforcing rib 29 regulates the one end edge of the battery 13 to 18 so as not to move in the axial direction by coming into contact with one edge of each of the batteries 13 to 18. The reinforcing ribs 28 and 29 prevent the electric field liquid from adhering to the circuit board 19 to cause a short circuit even if liquid leakage occurs in the batteries 13 to 18, and the case main body. 12 is reinforced.
[0020]
The substrate 19 is provided with an opening 30. A temperature sensor 31 such as a polyswitch, a thermal fuse, a thermostat, and a thermistor is disposed in the opening 30. Since the temperature sensor 31 is hollowly supported in the case body 12 without coming into contact with the substrate 19, the temperature in the battery pack 10 can be measured correctly.
[0021]
Further, the substrate 19 is provided with an opening 32 in a portion located between the batteries 13 and 14, and a tall electronic component 33 such as an IC, a resistor, a capacitor, a diode, or a transistor is disposed on the substrate 19, and the battery The pack 10 is thinned.
[0022]
One end of a ground lead 34 is connected to the circuit board 19. The other end of the ground lead wire 34 is connected to a ground terminal 25 fixed to the outer surface of the case lid 11. The ground terminal 25 is formed by fitting a thin metal plate into the concave portion of the case lid 11, and contacts the chassis of the electronic device when the battery pack 10 is attached to the electronic device. The ground terminal 25 has a function of setting a reference potential and shielding an electromagnetic wave generated from the microcomputer 42.
[0023]
As shown in FIG. 4, the six lithium ion batteries 13 to 18 are connected in series. A fuse 38, a charge stop FET (field effect transistor) 40, and a discharge stop FET 41 are connected between a positive electrode of the lithium ion battery 13 and a positive terminal 37 for connecting an electronic device. The fuse 38 is melted and disconnected when a large excessive current flows.
[0024]
The charge / discharge control circuit 36 is provided with a monitoring circuit and a switching circuit 39. The switching circuit 39 includes a charge stop FET 40 and a discharge stop FET 41. The charge stop FET 40 is turned OFF to stop charging when the lithium ion batteries 13 to 18 reach the charge stop voltage. The discharge stop FET 41 is turned OFF and stops discharging when the lithium ion batteries 13 to 18 are lowered to the discharge stop voltage.
[0025]
The monitoring circuit includes a measurement unit and a determination unit that determines an abnormality based on a signal from the measurement unit, and the switching circuit 39 is turned off when the abnormality is determined. As the determination unit, for example, a microcomputer 42 is used. The measurement unit includes a current measurement circuit 43 that measures the current of the lithium ion batteries 13 to 18, a voltage measurement circuit 44 that measures the voltage of the lithium ion batteries 13 to 18, and a temperature measurement that measures the heat generation temperature of the lithium ion batteries 13 to 18. The circuit 45 is configured.
[0026]
The voltage measuring unit 44 measures the voltage of each lithium ion battery 13-18. The current measuring unit 43 measures a current flowing through a resistor 47 having a known resistance value connected between the negative electrode of the lithium ion battery 18 and the negative terminal 46 for connecting an electronic device. For example, a thermistor or the like is used as the temperature sensor 31 in the temperature measurement circuit 45, and the temperature in the case is measured using the property that the resistance value decreases in proportion to the temperature.
[0027]
The microcomputer 42 determines a short circuit, overcurrent, overcharge, overdischarge, etc. based on the information obtained from the measurement unit described above, and controls the switching circuit 39 when determining abnormality of the batteries 13-18. Stop charging / discharging. When it is determined that the electronic device is not connected based on the signal level from the connection detection terminal 48 in the connector 24, the switching circuit 39 is turned off. Thereby, even if the plus terminal 37 and the minus terminal 46 are connected when the battery pack 10 is a single unit not connected to the electronic device or the charger, a short circuit does not occur. The ground terminal 25 is connected to the negative electrode of the battery 18 via the lead wire 34. The ground terminal 25 is connected to the chassis of the electronic device. This chassis is used as a ground for electronic equipment.
[0028]
Next, the operation of the above embodiment will be described. When the battery pack 10 is assembled, each electronic component constituting the charge / discharge control circuit 36 is mounted on the circuit board 19. Among these, the tall electronic component 33 is disposed inside the opening 32 provided in the substrate 19, and the thermistor 45 is disposed in the opening 30.
[0029]
Next, the battery connection plate 26 is soldered to the circuit board 19. Lithium ion batteries 13 to 18 are respectively inserted between the pair of battery connection plates 26. Thereafter, the battery connection plate 26 is spot welded to the electrodes of the lithium ion batteries 13 to 18. The assembled circuit board 19 is inserted into the case main body 12 with the batteries 13 to 18 facing downward, and the case lid 11 is fitted from above to complete the battery pack 10. Since the case lid 11 is coated with an adhesive, it is fixed to the case main body 12.
[0030]
In this state, the lithium ion batteries 13 to 18 enter the receiving portions 27 of the reinforcing rib 28 and are held away from the inner wall, and the batteries 13 to 18 of each set are held away from each other. Since the receiving portion 27 has an arc shape, the battery is reliably prevented from moving in the diameter direction, and the reinforcing ribs 29 prevent the batteries 13 to 18 from moving in the axial direction. 13 to 18 are fixed so as not to move. Thereby, even when the battery pack 10 is vibrated, spot welding of the batteries 13 to 18 and the battery connection plate 26 and soldering of the circuit board 19 are not removed.
[0031]
When the battery pack 10 is set in the charger, the microcomputer 42 turns on the two FETs 40 and 41. The current from the charger flows through the fuse 38 and the FETs 40 and 41 to the lithium ion batteries 13 to 18 to charge the lithium ion batteries 13 to 18. If any one of the batteries reaches the charge stop voltage during the charging, the microcomputer 42 turns off the charge stop FET 40.
[0032]
When the battery pack 10 is mounted on the electronic device, the microcomputer 42 turns on the two FETs 40 and 41 to supply the voltage from the lithium ion batteries 13 to 18 to the electronic device. If any one lithium ion battery drops to the discharge stop voltage during the supply, the microcomputer 42 turns off the discharge stop FET 41.
[0033]
During charging / discharging, the current measurement circuit 43 measures the current. When the current value exceeds the allowable value, the microcomputer 42 turns off one of the discharge stop FET 40 or the charge stop FET 41. When the temperature in the case measured by the thermistor 45 increases, the microcomputer 42 turns off one of the two FETs 40 and 41. Further, during charging / discharging, the microcomputer 42 exchanges battery information (voltage, current, temperature, remaining battery amount, etc.) with an electronic device or a charger via the external connection terminal 48.
[0034]
In the above embodiment, the six batteries 13 to 18 are connected in series. However, two batteries connected in parallel may be used as one set, and three sets may be connected in series.
[0035]
In the above embodiment, six batteries are used. However, one or more batteries may be used in the present invention. Furthermore, in the said Example, although the lithium ion battery is used as a secondary battery, a nickel cadmium battery etc. may be sufficient.
[0036]
【The invention's effect】
As described above, in the battery pack of the present invention, since the rib is provided on the inner wall of the case, sufficient strength can be ensured and deformation or the like can be prevented even in a thin case. Moreover, since the battery movement restricting portion is formed on the rib, the secondary battery can be fixed so as not to move in the case. Further, since the secondary battery is fixed using the ribs, no special member is required, the assembly is simple, and the cost can be reduced. Further, since the secondary batteries are held apart from each other by a predetermined distance, the batteries do not adhere to each other. Therefore, when one battery generates heat, heat is not transmitted to the other battery.
[0037]
In addition, since the concave receiving portion is formed on the rib perpendicular to the axial direction of the secondary battery, and a part of the outer periphery of the secondary battery is fitted into the receiving portion, the secondary battery can be moved in the lateral direction. In addition, when the battery pack is dropped, a part of the impact is absorbed, so that the performance deterioration of the secondary battery due to the impact can be eliminated. Moreover, since the edge of the rib extended in the axial direction of the secondary battery is made to contact the electrode of the secondary battery, the movement of the secondary battery in the axial direction can be prevented.
[0038]
Since the opening is provided in the circuit board and the electronic component is placed therein, the electronic component is exposed to the upper surface or the lower surface of the circuit board without contacting the circuit board. Therefore, when the electronic component is a temperature sensor, the temperature in the case can be correctly measured even if the case is partitioned vertically by the circuit board. In the case of an electronic component having a height, the height of the case can be reduced by placing the electronic component in a state of being inserted into the opening.
[0039]
Furthermore, since the electronic component is arranged in a gap formed between two adjacent secondary batteries, the circuit board can be reduced in size. In addition, since the ground terminal is provided on the outer surface of the case, it is possible to set the reference potential of the secondary battery and shield the electromagnetic wave generated from the charge / discharge control circuit.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a battery pack of the present invention.
FIG. 2 is a longitudinal sectional view of a battery pack.
FIG. 3 is a cross-sectional view of the battery pack.
FIG. 4 is a circuit diagram of a charge / discharge control circuit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Battery pack 13-18 Lithium ion battery 19 Circuit board 25 Ground terminal 27 Receiving part 28, 29 Reinforcement rib 30, 32 Opening 31 Thermistor 36 Charge / discharge control circuit

Claims (6)

In a battery pack in which a circuit board on which a plurality of cylindrical secondary batteries and a charge / discharge control circuit for controlling their charge / discharge are mounted in a plastic case,
Formed integrally on the inner wall of the case is a battery movement restricting portion for restricting the movement of the plurality of secondary batteries in the axial direction and the radial direction at a predetermined distance between the plurality of secondary batteries. A battery pack comprising a plurality of ribs.   The battery pack according to claim 1, wherein the battery movement restricting portion is a concave receiving portion, and a part of an outer periphery of the secondary battery is fitted therein.   2. The battery pack according to claim 1, wherein the battery movement restricting portion is one end of a rib, and the one end contacts an edge of the secondary battery on the electrode side so as not to move in the axial direction.   2. The battery pack according to claim 1, wherein an opening is provided in the circuit board, and a part of the electronic components constituting the charge / discharge control circuit is disposed in the opening.   The battery according to claim 1, wherein a part of the electronic components constituting the charge / discharge control circuit is arranged in a gap between two secondary batteries attached in parallel to the circuit board. pack.   2. The battery pack according to claim 1, wherein a ground terminal for connecting a ground of the circuit board to a chassis ground of an electronic device to be externally connected is exposed to the outside of the case.

Images