Electric hand-held power tool with a shut-off delay device

• US 8,305,042 B2
• Filed: 03/27/2007
• Issued: 11/06/2012
• Est. Priority Date: 04/11/2006
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Wirnitzer, Bernd, Glauning, Rainer
• Primary Examiner(s): Muralidar, Richard V
• Application Number:
  US11/997,020
• Publication Number:
  US 20080224666A1
• Time in Patent Office: 2,051 Days
• Field of Search: 320134-136, 320/132, 361/83, 361/89, 361/90, 361/92
• US Class Current: 320/136
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

The invention relates to a handheld electrical machine tool having at least one electrical drive, at least one electrical device requiring electrical energy for its operation, a shut-off delay apparatus for the electrical drive and/or the electrical device and having at least one rechargeable battery for the electrical supply to the drive and the electrical device. Provision is made for the handheld electrical machine tool to have an exhaustive discharge protection apparatus (8), which predetermines the delay time (t) of the shut-off delay apparatus (3) as a function of the state of charge of the rechargeable battery (9) detected by it. In addition, the invention relates to a corresponding method.

Claims

1. An electric hand-held power tool includes at least one electrical drive, at least one electrical device that requires electrical energy in order to operate, a shut-off delay device (3) for the electrical drive and/or the electrical device, at least one rechargeable battery (9) for supplying electrical energy to the drive and the electrical device, and an exhaustive-discharge safeguard device (8), which specifies a delay time (Δ

t) of the shut-off delay device (3) as a function of the state of charge of the rechargeable battery (9) it has determined,

wherein the exhaustive-discharge safeguard device (8) specifies a shorter delay time (Δ

t) of the shut-off delay device (3) when the rechargeable battery (9) has a lower state of charge.

2. The electric hand-held power tool as recited in claim 1, wherein the shut-off delay device (3) includes the exhaustive-discharge safeguard device (8).

3. The electric hand-held power tool as recited in claim 1, wherein the shut-off delay device (3) does not provide a shut-off delay when the state of charge of the rechargeable battery (9) is below a critical charge threshold.

4. A method for operating an electric hand-held power tool with at least one electrical drive, at least one electrical device that requires electrical energy in order to operate, a shut-off delay device for the electrical drive and/or the electrical device, at least one rechargeable battery for supplying electrical energy to the drive and the electrical device, and an exhaustive-discharge safeguard device, comprising steps of:

detecting by the exhaustive-discharge safeguard device (8) a state of charge of the rechargeable battery and,

specifying by the exhaustive-discharge safeguard device, as a function of this state of charge, a delay time with which the electric device is switched off with delay by the shut-off delay device,

wherein the exhaustive-discharge safeguard device specifies a shorter delay time of the shut-off delay device when the rechargeable battery has a lower state of charge.

5. The method as recited in claim 4, wherein the shut-off delay device switches off the electrical device without a shut-off delay when the state of charge of the rechargeable battery is below a critical charge threshold.

6. The method as recited in claim 4, wherein the delay time is restricted to predetermined values.

7. The method as recited in claim 4, wherein the exhaustive-discharge safeguard device specifies the delay time with the state of charge of the rechargeable battery in a continually-modified manner until the critical charge threshold is reached.

8. The method as recited in claim 4, wherein the exhaustive-discharge safeguard device specifies the delay time with the state of charge of the rechargeable battery in a stepwise-modified manner.

9. The method as recited in claim 4, wherein the exhaustive-discharge safeguard device determines the state of charge of the rechargeable battery by measuring the voltage of the rechargeable battery.

10. The method as recited in claim 4, wherein the voltage of the rechargeable battery is measured together with a related current under electrical load.

11. The method as recited in claim 4, wherein the voltage of the rechargeable battery is measured in a nearly currentless manner.

12. The method as recited in claim 4, wherein the exhaustive-discharge safeguard device allows the electrical drive to be switched on only when the state of charge of the rechargeable battery is above a drive switch-on charge threshold.

13. The method as recited in claim 4, wherein the exhaustive-discharge safeguard device allows the electrical device to be switched on only when the state of charge of the rechargeable battery is above a device switch-on charge threshold.

14. An electric hand-held power tool with at least one electrical drive, at least one electrical device that requires electrical energy in order to operate, a shut-off delay device for the electrical drive and/or the electrical device, and with at least one rechargeable battery for supplying electrical energy to the drive and the electrical device, characterized by an exhaustive-discharge safeguard device, which specifies a delay time (Δ

t) of the shut-off delay device as a function of the state of charge of the rechargeable battery it has determined and specifies a shorter delay time (Δ

t) of the shut-off delay device when the rechargeable battery has a lower state of charge.

15. A method for operating an electric hand-held power tool with at least one electrical drive, at least one electrical device that requires electrical energy in order to operate, a shut-off delay device for the electrical drive and/or the electrical device, and with at least one rechargeable battery for supplying electrical energy to the drive and the electrical device,

wherein an exhaustive-discharge safeguard device of the electric hand-held power tool detects the state of charge of the rechargeable battery and, as a function of this state of charge, specifies a delay time with which the electric device is switched off with delay by the shut-off delay device, wherein a shorter delay time of the shut-off delay device is specified when the rechargeable battery has a lower state of charge.