Knife with automatic blade retraction

1. A knife with automatic blade retraction, the knife comprising:

a housing;

a moveable actuating housing including a plurality of sidewalls;

a moveable slide member;

a rotatable blade unit rotatably attached to the moveable slide member, the rotatable blade unit including a blade and a blade carrier, the rotatable blade unit partially disposed within the plurality of sidewalls of the moveable actuating housing, the blade being connected to the blade carrier such that rotary movement between the blade and the blade carrier is prevented, the blade carrier including an entrainment member configured to be brought into engagement with an abutment surface of the moveable actuating housing, the rotatable blade unit moveable by the moveable actuating housing between a first position in which the blade is retracted in the housing and a second position in which the blade is extended from the housing, and the rotatable blade unit rotatable by the action of cutting force in the second position from an engagement position in which the entrainment member of the blade carrier is in engagement with the abutment surface of the moveable actuating housing into a release position in which the entrainment member of the blade carrier is not in engagement with the abutment surface of the moveable actuating housing; and

a first retraction element configured to continuously apply a retraction force to the rotatable blade unit in the direction of the retracted position.

2. The knife of claim 1 , wherein the slide member and the rotatable blade unit are jointly displaceable along a longitudinal axis between the retracted position and the extended position.

3. The knife of claim 1 , wherein the slide member is configured to be guided such that rotary movement of the slide member is substantially prevented.

4. The knife of claim 1 , wherein the slide member has an abutment that, in the extended position of the rotatable blade unit, is configured to cooperate in positively locking relationship with the housing or the moveable actuating housing such that further extension of the rotatable blade unit is prevented.

5. The knife of claim 1 , wherein the rotatable blade unit includes an entrainment member that, in the engagement position of the rotatable blade unit, is configured to be brought into engagement in positively locking relationship with the moveable actuating housing.

6. The knife of claim 1 , wherein the first retraction element is configured to apply a retraction force to the rotatable blade unit in a direction of the engagement position.

7. The knife claim 1 , further comprising:

a holding mechanism including the housing or the moveable actuating housing, the holding mechanism further including the rotatable blade unit, and the holding mechanism configured to prevent rotary movement of the rotatable blade unit in a direction of the engagement position, after the rotatable blade unit is in the release position, in a movement of the rotatable blade unit from the extended position in a direction of the retracted position.

8. The knife of claim 7 , wherein the holding mechanism is configured to permit the rotary movement of the rotatable blade unit in the direction of the engagement position when the retracted position of the rotatable blade unit is reached.

9. The knife of claim 8 , wherein the holding mechanism comprises a latching mechanism including a first latching element and a second latching element configured to mutually cooperate with the first latching element, the housing or the moveable actuating housing includes the first latching element, and the rotatable blade unit includes the second latching element.

10. The knife of claim 9 , wherein the first latching element includes a hook portion and the second latching element includes a latching edge, and upon rotary movement of the rotatable blade unit in the extended position from the engagement position into the release position, the hook portion engages over the latching edge such that rotary movement of the rotatable blade unit from the release position back into the engagement position is prevented.

11. The knife of claim 10 , wherein the first latching element is elastically deflected during the rotary movement of the rotatable blade unit from the engagement position into the release position when the rotatable blade unit is in the extended position.

12. The knife of claim 10 , wherein the first latching element includes a leg that is in contact with the rotatable blade unit in the engagement position of the rotatable blade unit, the release position of the rotatable blade unit, or a combination thereof.

13. The knife of claim 1 , wherein the moveable actuating housing is configured to be moveable between a passive position and a cutting position, and a second retraction element is configured to apply a retraction force to the actuating device in the direction of the passive position.

14. The knife of claim 1 , wherein the blade is connected to the blade carrier by an adhesive connection, a stamped connection, a screw connection, a damping connection, or a combination thereof.

15. The knife of claim 1 , wherein the blade includes a plurality of apertures and the blade carrier includes a plurality of projections that engage the plurality of apertures to connect the blade carrier and the blade.

16. The knife of claim 1 , wherein the blade carrier remains unengaged with the moveable actuating housing when in the release position.

17. The knife of claim 1 , wherein the rotatable blade unit is rotatably attached to the moveable slide member such that rotational movement of the rotatable blade unit with respect to the moveable slide member is allowed and a relative translational movement of the rotatable blade unit with respect to the moveable slide member is inhibited.