Protective Device at least for Protecting a User in the Event of an Uncontrolled Blockage of a Portable Power Tool

Patent metadata

Field	Value
Publication number	US-2016288308-A1
Application number	US-201615083026-A
Country	US
Kind code	A1
Filing date	Mar 28, 2016
Priority date	Mar 30, 2015
Publication date	Oct 6, 2016
Grant date	—

Abstract

A protective device at least for protecting a user in the event of an uncontrolled blockage of a portable power tool includes at least one rotationally drivable shaft and at least one wrap-spring-free overload clutch unit which is arranged on the shaft and is configured at least to interrupt transmission of a drive force if a torque limit is exceeded. The protective device further including at least one wrap-spring clutch unit configured to brake the shaft.

First claim

What is claimed is:

1 . A protective device at least for protecting a user in the event of an uncontrolled blockage of a portable power tool, comprising:
at least one rotationally drivable shaft; at least one wrap-spring-free overload clutch unit which is arranged on the shaft and is configured at least to interrupt transmission of a drive force if a torque limit is exceeded; and at least one wrap-spring clutch unit configured to brake the shaft.

2 . The protective device according to claim 1 , wherein the wrap-spring clutch unit comprises:
at least one driver element connected to a free end of the shaft; and at least one wrap-spring element configured to cooperate with the driver element in order to brake the shaft.

3 . The protective device according to claim 2 , wherein the driver element is connected to the shaft for conjoint rotation.

4 . The protective device according to claim 1 , wherein the wrap-spring clutch unit comprises:
at least one activation unit including at least one movably mounted activation element configured to bring about a winding movement of a wrap-spring element of the wrap-spring clutch unit as a result of a relative movement.

5 . The protective device according to claim 1 , wherein the wrap-spring clutch unit comprises:
at least one activation unit which has at least one movably mounted activation element that is mounted so as to be twistable through an angle of less than 360°.

6 . The protective device according to claim 1 , further comprising:
at least one bearing flange on which the shaft is rotatably mounted, wherein the wrap-spring clutch unit has at least one wrap-spring element which bears against the bearing flange at least during a rotational movement of the shaft and is not in contact with the shaft or with a driver element, arranged on the shaft, of the wrap-spring clutch unit.

7 . The protective device according to claim 6 , wherein:
one end of the wrap-spring element is fixed to the bearing flange and another end is fixed to an activation element of an activation unit of the wrap-spring clutch unit, and the activation element is twistable through less than 360°.

8 . The protective device according to claim 1 , wherein the wrap-spring clutch unit comprises:
at least one wrap-spring element, one end of which is fixed to a driver element of the wrap-spring clutch unit, the driver element being connected to the shaft for conjoint rotation, and the other end of which is fixed to a rotatably mounted activation element of an activation unit of the wrap-spring clutch unit.

9 . The protective device according to claim 8 , further comprising:
at least one bearing flange on which the shaft is rotatably mounted, wherein the activation unit has at least one magnetic element which is configured to produce a force fit between the bearing flange and the wrap-spring element as a result of a rotational movement of the activation element being braked.

10 . The protective device according to claim 1 , wherein the wrap-spring clutch unit comprises:
at least one wrap-spring element having two different coil diameters.

11 . The protective device according to claim 1 , wherein the wrap-spring clutch unit comprises:
at least one wrap-spring element which is surrounded at least partially by the shaft.

12 . The protective device according to claim 11 , wherein the shaft has an internal cutout in which the wrap-spring element is fixed at least with one end.

13 . The protective device according to claim 11 , further comprising:
at least one bearing flange on which the shaft is rotatably mounted, wherein the wrap-spring element extends through a cutout in the bearing flange.

14 . The protective device according to claim 1 , wherein the wrap-spring clutch unit is arranged at an end of the shaft which is remote from a further end of the shaft at which the overload clutch unit is arranged.

15 . A portable power tool, comprising:
at least one percussion mechanism unit; and at least one protective device configured to protect a user in the event of an uncontrolled blockage of the portable power tool, the protective device including (i) at least one rotationally drivable shaft, (ii) at least one wrap-spring-free overload clutch unit which is arranged on the shaft and is configured at least to interrupt transmission of a drive force if a torque limit is exceeded, and (iii) at least one wrap-spring clutch unit configured to brake the shaft.

16 . The portable power tool of claim 15 , wherein the portable power tool is a hammer drill or a chipping hammer.

Assignees

• Bosch Gmbh Robert

Inventors

• Kuhnle Axel
• Schmid Lars
• Diem Carsten

Classifications

• B25F5/00 Primary

  Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for · CPC title

• B25D2250/221

  Sensors · CPC title

• B25D2250/371

  Use of springs · CPC title

• B25D2250/141

  Magnetic parts used in percussive tools · CPC title

• B25D16/003 Primary

  Clutches specially adapted therefor · CPC title