Battery packs having improved heat radiation

• US 20030096160A1
• Filed: 12/19/2002
• Published: 05/22/2003
• Est. Priority Date: 10/15/1998
• Status: Active Grant

• Current Assignee: Makita Corporation
• Original Assignee: Makita Corporation
• Inventors: Sugiura, Masatoshi, Kato, Youichi, Sakakibara, Kazuyuki
• Granted Patent: US 7,211,347 B2
• Time in Patent Office: Days
• US Class Current: 429/120
• CPC Class Codes: H01M 10/345 Gastight metal hydride accumulators
• CPC Class Codes: H01M 10/613 Cooling or keeping cold
• CPC Class Codes: H01M 10/6235 Power tools
• CPC Class Codes: H01M 10/643 Cylindrical cells
• CPC Class Codes: H01M 10/653 characterised by electrically insulating or thermally conductive materials
• CPC Class Codes: H01M 10/6551 Surfaces specially adapted for heat dissipation or radiation, e.g. fins or coatings
• CPC Class Codes: H01M 10/6557 arranged between the cells
• CPC Class Codes: H01M 10/6563 with forced flow, e.g. by blowers
• CPC Class Codes: H01M 10/6566 Means within the gas flow to guide the flow around one or more cells, e.g. manifolds, baffles or other barriers H01M10/6565 takes precedence
• CPC Class Codes: H01M 50/213 adapted for cells having curved cross-section, e.g. round or elliptic H01M50/209, H01M50/216 take precedence
• CPC Class Codes: H01M 50/253 adapted for specific cells, e.g. electrochemical cells operating at high temperature
• CPC Class Codes: H01M 50/296 characterised by terminals of battery packs terminals of batteries H01M50/543
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A battery pack (1) has a double casing structure, including an inner case (2) disposed inside an outer case (3). The inner case (2) includes a radiator plate (9) that is in contact with the side walls of battery cells (4) disposed within the battery pack (1). A forked air passage (32) extends from an air inlet (27) and is defined between the inner case (2) and the outer case (3) and along the outer surface of the radiator plate (9) until reaching a pair of air outlets (31).

Claims

1. A battery pack for a power tool comprising:

a housing comprising charging and discharging terminals disposed on the housing for alternatively coupling with the power tool and a battery charger,

a plurality of battery cells disposed within the housing,

an air passage defined within the housing, thereby enabling cooling air to pass through the housing,

a partition separating the air passage from portions of the battery cells connected to the charging and discharging terminals, and

a heat conductive and electrically insulating material in communication with the battery cells and the air passage.

2. A battery pack as in claim 1, further comprising an air inlet defined within the housing and in communication with the air passage, the air inlet adapted to receive cooling air from the battery charger.

3. A battery pack as in claim 2, further comprising first and second air outlets, wherein forced air received by the air inlet is divided and a first portion of the cooling air is directed along a first path and exhausted through the first air outlet, and a second portion of the cooling air is directed along a second path and exhausted through the second air outlet.

4. A battery pack as in claim 2, wherein the air inlet is arranged and constructed to communicate with an air outlet defined in the power tool, the air inlet being adapted to receive cooling air from a fan disposed within the power tool.

5. A battery pack as in claim 4, wherein the air inlet is also arranged and constructed to communicate with an air outlet defined in the battery charger, the air inlet being adapted to receive cooling air from a fan disposed within the battery charger.

6. A battery pack as in claim 5, further comprising air directors for directing cooling air from the battery charger to the air passage.

7. A battery pack as in claim 1, wherein the battery cells are nickel metal hydride battery cells connected in series.

8. A battery pack as in claim 1, further comprising a temperature sensor in communication with at least one battery cell.

9. A battery pack as in claim 1, wherein the battery cells are arranged and constructed to begin charging when the charging and discharging terminals contact a battery charger.

10. An apparatus comprising:

a removable battery pack comprising a housing, a plurality of battery cells disposed within the housing, terminals coupled to the battery cells, an air passage disposed within the housing, an air inlet defined within the housing and in communication with the air passage, a partition separating the air passage from the terminals coupled to the battery cells and a heat conductive, electrically insulating material in communication with the battery cells and the air passage; and

a battery charger comprising a housing, terminals disposed on the housing and arranged and constructed to communicate with the battery pack terminals, a fan disposed within the housing, and a forced air outlet defined to communicate with the battery pack air inlet, wherein the fan is arranged and constructed to force cooling air through the forced air outlet and through the air inlet and across the heat conductive, electrically insulating material, so as to cool the battery cells during a battery charging operation.

11. An apparatus as in claim 10, wherein the battery charger is arranged and constructed to automatically energize the battery charger terminals in order to charge the battery cells when the battery charger terminals contact the battery pack terminals.

12. An apparatus as in claim 11, wherein the removable battery pack further comprises a temperature sensor in communication with at least one battery cell.