Safety switch device for a rotary powered hand tool

• US 20040011632A1
• Filed: 10/17/2001
• Published: 01/22/2004
• Est. Priority Date: 10/19/2000
• Status: Abandoned Application

• Current Assignee: Hilti Aktiengesellschaft (Hilti Martin Family Trust)
• Original Assignee: Hilti Aktiengesellschaft (Hilti Martin Family Trust)
• Inventors: Hellmann, Peter, Osselmann, Claus
• Application Number:
  US09/981,520
• Publication Number:
  US 20040011632A1
• Time in Patent Office: Days
• US Class Current: 200/179
• 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

Abstract

A safety switch device (6) for the generation of a control signal (Θ) when the future angle of deflection of the housing of a rotary electrically powered hand tool exceeds a predetermined value, wherein a rotational rate sensor (7) directly measuring the rotational velocity (ω) is connected to a comparison element (8) in a signal-transferring fashion.

Claims

1. A safety switch device for the generation of a control signal (Θ

) when a future angle of deflection of the housing of an at least partially rotary powered hand tool (1) is exceeded, wherein a rotational rate sensor (7) directly measuring the rotational acceleration (ω

) is connected to a comparison element (8) in a signal transferring fashion.

2. The safety switch device of claim 1, wherein the rotational rate sensor (7) is an active sensor device that measures on the basis of Coriolis forces.

3. The safety switch device of claim 1, wherein a functional unit (9, 9′

) is arranged in a signal transferring fashion between the rotational rate sensor (7) and the comparison element (8).

4. The safety switch device of claim 1, wherein the functional unit (9) comprises a weighted summation element (IV) having an integrator element (III) arranged upstream at one input.

5. The safety switch device of claim 1, wherein the functional unit (9) is realized without a means for integration of the rotational acceleration (ω

).

6. The safety switch device of claim 1, wherein the functional unit (9) comprises a low pass filter (II) having a critical frequency between 10 and 100 Hz.

7. The safety switch device of claim 1, wherein the functional unit (9) comprises a high pass filter (I) having a critical frequency between 0.5 and 10 Hz.

8. The safety switch device of claim 1, wherein the starting point can be determined for calculation of the control signal (Θ

) at the point in time of switch-on of the electrical drive (2).

9. The safety switch of claim 1, wherein the functional unit (9′

) comprises a microcontroller that uses software algorithms of a microcontroller.

10. The safety switch device of claim 1, wherein at least one of a current path of an electrical drive (2) is interrupted, by a control signal (Θ

), by a cut-off switch and the power flow from the electrical drive (2) to a tool spindle (3) is interrupted, and wherein the control signal (Θ

) is produced by the comparison element (8) after comparison of a plurality of measured values (M, M′

) to a predetermined threshold value (S).