Positive and negative terminals formed on a top face of a unit cell and positive and negative terminals formed on a surface of a circuit board opposed to the unit cell are electrically connected to each other by connectors. The connectors each include an elastic body formed from an elastic material, and a conductor which is placed so as to be exposed on upper and lower surfaces of the elastic body and which serves for electrically connecting those exposed portions to each other. By elastic restoring force of the elastic body generated by elastic compression of the elastic body between the terminals, the upper and lower surfaces of the connectors are put into press contact between the opposing positive and negative terminals of the unit cell and the circuit board, by which their electrical connection is maintained.
1. A battery pack comprising:
a unit cell in which a first electrode terminal is formed on a terminal formation surface;
an exterior cover fixed so as to cover the terminal formation surface of the unit cell;
a circuit board which has a protection circuit for controlling a charging current and a second electrode terminal electrically connected to the protection circuit, and which is placed inside the exterior cover so that the second electrode terminal is opposed to the first electrode terminal of the terminal formation surface of the unit cell; and
a connector placed between the first electrode terminal and the second electrode terminal so as to electrically connect the first electrode terminal and the second electrode terminal to each other, wherein
the connector comprises:
an elastic body formed from an elastic material; and
a conductor which is fixed to the elastic body so as to be exposed at, at least, opposite positions in surfaces of the elastic body and which makes the exposed portions in the opposite positions electrically connected to each other, wherein
in a state that the elastic body is elastically compressed so that the exposed portions of the conductor in the opposite positions are in press contact with the first electrode terminal and the second electrode terminal, respectively, the first electrode terminal and the second electrode terminal are maintained electrically connected to each other by the connector.
2. The battery pack as defined in claim 1 , wherein the elastic body is formed from a rubber material.
3. The battery pack as defined in claim 1 , wherein the conductor is a conductive thin film placed on the surface of the elastic body.
4. The battery pack as defined in claim 1 , wherein the conductor is a plurality of conductive linear members placed on the surface of the elastic body.
5. The battery pack as defined in claim 4 , wherein a plurality of conductive linear members are wound on the surface of the elastic body.
6. The battery pack as defined in claim 1 , further comprising
a holder for holding the circuit board, the holder being fixed, inside the exterior cover, to the terminal formation surface of the unit cell, wherein
the holder comprises:
a connector holding portion having a through hole shape for holding a placement position of the connector in a state that the conductor is in contact with the first electrode terminal of the unit cell; and
a circuit board holding portion having a recessed shape for holding the circuit board in a state that the elastic body is elastically compressed while the second electrode terminal of the circuit board is kept in contact with the conductor of the connector held by the connector holding portion.
7. The battery pack as defined in claim 6 , wherein the exterior cover and the holder are formed from resin material, and the exterior cover and the holder are joined and fixed to each other by ultrasonic welding.
8. The battery pack as defined in claim 7 , wherein
protrusive junction portions are provided in opposing surfaces of the exterior cover and the holder, and
the junction portions and an outer surface of the holder are integrally united together by ultrasonic welding, whereby the exterior cover and the holder are joined and fixed together.
9. The battery pack as defined in claim 8 , wherein
a support member for fixing the exterior cover and the holder is fixed at an upper end portion of the unit cell,
the support member is an L-shaped metal fixture including a leg piece whose one end is fixed to the unit cell and which extends vertically, and a horizontal piece which adjoins the other end of the leg piece and which is bent horizontally,
a through hole into which a protrusive junction portion is to be inserted is formed in the horizontal piece,
the holder and the circuit board are placed between an upper end of the unit cell and the horizontal piece, and
forward ends of the junction portions inserted into the through holes and the outer surface of the holder are integrally united together by ultrasonic welding, whereby the exterior cover and the holder are fixed to the support member.