Monitoring system for electric power tool, battery pack for electric power tool, and battery charger for electric power tool

• US 8,384,349 B2
• Filed: 10/01/2009
• Issued: 02/26/2013
• Est. Priority Date: 10/08/2008
• Status: Active Grant

• Current Assignee: Makita Corporation
• Original Assignee: Makita Corporation
• Inventors: Suzuki, Hitoshi, Kobayakawa, Tadahiko, Muramatsu, Tomoo
• Primary Examiner(s): Fantu, Yalkew
• Application Number:
  US12/588,042
• Publication Number:
  US 20100085008A1
• Time in Patent Office: 1,244 Days
• Field of Search: 320/112
• US Class Current: 320/112
• CPC Class Codes: B25F 5/00 Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
• CPC Class Codes: H01M 10/4207 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/4257 Smart batteries, e.g. electronic circuits inside the housing of the cells or batteries
• CPC Class Codes: H01M 10/482 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/486 for measuring temperature
• CPC Class Codes: H01M 50/543 Terminals
• CPC Class Codes: H02J 7/0063 with circuits adapted for supplying loads from the battery
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: H02J 7/007194 of the battery
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A battery monitoring system for electric power tool includes a battery pack for electric power tool and an auxiliary power source. The battery pack has a battery and a monitoring circuit. The battery is provided with at least one battery cell. The monitoring circuit is operated by electric power supplied from the battery, and monitors a status of the battery. The auxiliary power source outputs electric power allowing the monitoring circuit to operate. The monitoring circuit is configured such that, when the monitoring circuit is unoperational with the electric power of the battery due to a decrease in a voltage of the battery, the monitoring circuit becomes operational by the electric power supplied from the auxiliary power source.

Claims

1. A battery monitoring system for electric power tool comprising a battery pack for electric power tool, a battery charger for the electric power tool, and an auxiliary power source,

wherein the battery pack includes:

a battery that is used as a driving power source for electric power tool and has at least one battery cell; and

a monitoring circuit that is operated by electric power supplied from the battery and monitors a status of the battery,

the battery charger is configured such that the battery charger is detachably attached to the battery pack, and the battery charger generates and outputs charging power for charging the battery, and

the auxiliary power source is provided inside or separately from the battery pack and outputs electric power allowing the monitoring circuit to operate,

wherein the monitoring circuit is configured to be operational by the electric power supplied from the auxiliary power source when the monitoring circuit becomes unoperational with the electric power of the battery due to a decrease in a voltage of the battery, and includes;

a chargeability determination unit that determines whether or not the battery is in a chargeable state by monitoring the battery; and

a signal output unit that outputs, as one of the monitored items, a charge permission signal to the battery charger when the battery is determined to be in a chargeable state by the chargeability determination unit, the charge permission signal indicating that the battery is in a chargeable state,

wherein the battery charger outputs the charging power to the battery pack when the charge permission signal is inputted to the battery charger from the battery pack.

2. The battery monitoring system according to claim 1,

wherein the at least one battery cell included in the battery is a rechargeable battery cell, and

wherein the auxiliary power source is provided inside the battery charger and the auxiliary power source is configured to be capable of supplying the electric power of the auxiliary power source to the battery pack when the battery pack is attached to the battery charger.

3. The battery monitoring system according to claim 1,

wherein the battery charger includes a charger-side terminal that outputs the electric power of the auxiliary power source to the battery pack, and

wherein the battery pack includes a battery pack-side terminal which is connected to the charger-side terminal when the battery pack is attached to the battery charger, and the electric power of the auxiliary power source outputted from the charger-side terminal is inputted to the battery pack through the battery pack-side terminal.

4. The battery monitoring system according to claim 1,

wherein the battery pack includes an output terminal that outputs monitored items by the monitoring circuit to the battery charger, and

wherein the battery charger includes an input terminal which is connected to the output terminal when the battery pack is attached to the battery charger, and the monitored items outputted from the output terminal is inputted to the battery charger through the input terminal.

5. The battery monitoring system according to claim 4,

wherein the signal output unit outputs the charge permission signal to the output terminal, and

wherein the battery charger outputs the charging power to the battery pack when the charge permission signal is inputted to the battery charger from the battery pack via the input terminal.

6. The battery monitoring system according to claim 1,

wherein the battery pack further includes a connection detecting unit which detects that the battery pack is attached to the battery charger based on an input of the electric power of the auxiliary power source, when the electric power of the auxiliary power source is inputted to the battery pack as a result of the battery pack being attached to the battery charger.

7. The battery monitoring system according to claim 1,

wherein the battery pack further includes a power supply circuit to which the voltage of the battery and the voltage of the auxiliary power source are inputted, and the power supply circuit generates an operating power source for operating the monitoring circuit based on one of the voltage of the battery and the voltage of the auxiliary power source, and

wherein the monitoring circuit is configured to be operational with the operating power source generated by the power supply circuit.

8. The battery monitoring system according to claim 7, wherein the power supply circuit generates the operating power source based on a greater one of the voltage of the battery and the voltage of the auxiliary power source.

9. The battery monitoring system according to claim 8, wherein the power supply circuit comprises:

a generating circuit to which one of the voltage of the battery and the voltage of the auxiliary power source is inputted, and the generating circuit generating the operating power source based on the voltage inputted;

a first diode having a cathode connected to an input side of the generating circuit, and an anode to which the voltage of the battery is inputted, and

a second diode having a cathode connected to the input side of the generating circuit, and an anode to which the voltage of the auxiliary power source is inputted.

10. The battery monitoring system according to claim 7,

wherein the battery pack further includes an output stopping unit which is provided on a current-carrying path extending from where the voltage of the auxiliary power source is inputted to the battery pack to where the voltage of the auxiliary power source reaches the power supply circuit, and the output stopping unit inhibits the voltage of the battery to be inputted to the power supply circuit from being outputted to an auxiliary power source side via the current-carrying path.

11. The battery monitoring system according to claim 10,

wherein the output stopping unit is a third diode having:

a cathode connected to the power supply circuit; and

an anode to which the voltage of the auxiliary power source is inputted.

12. The battery monitoring system according to claim 10, wherein the output stopping unit is a fuse.

13. A battery pack for electric power tool comprising:

a battery having at least one battery cell; and

a monitoring circuit that is operated by electric power supplied from the battery, and monitors a status of the battery;

wherein the monitoring circuit is configured to be operational by electric power supplied from an auxiliary power source different from the battery when the monitoring circuit is unoperational with electric power of the battery due to a decrease in a voltage of the battery, and includes;

a chargeability determination unit that determines whether or not the battery is in a chargeable state by monitoring the battery; and

a signal output unit that outputs, as one of the monitored items, a charge permission signal to a battery charger for the electric power tool when the battery is determined to be in a chargeable state by the chargeability determination unit, the charge permission signal indicating that the battery is in a chargeable state, and

wherein the battery pack is configured to be supplied with charging power from the battery charger when the charge permission signal is inputted into the battery charger.

14. A battery charger for electric power tool configured such that the battery charger is detachably attached to a battery pack for electric power tool, the battery pack including:

a battery having at least one battery cell; and

a monitoring circuit being operated by electric power supplied from the battery and monitoring a status of the battery, the monitoring circuit including;

a chargeability determination unit that determines whether or not the battery is in a chargeable state by monitoring the battery; and

a signal output unit that outputs, as one of the monitored items, a charge permission signal to the battery charger when the battery is determined to be in a chargeable state by the chargeability determination unit, the charge permission signal indicating that the battery is in a chargeable state,

wherein the battery charger generates and outputs charging power for charging the battery,

wherein the battery charger further includes an auxiliary power source that outputs electric power allowing the monitoring circuit to operate, and

wherein the battery charger is configured to be capable of supplying the electric power of the auxiliary power tool to the battery pack when the battery pack is attached to the battery charger, and is configured to output the charging power to the battery pack when the charge permission signal is inputted from the battery pack.