Belt retractor

1. A belt retractor for a safety belt, comprising:

a belt spindle for winding up and unwinding the safety belt;

a lockable locking flange connected to the belt spindle;

a force transmission element, which is held in a recess of the belt spindle and can be in engagement with the locking flange and can connect the belt spindle to the locking flange;

a tautener drive; and

an inertia element located between the belt spindle and the locking flange and being movable between a first position and a second position relative to the belt spindle, the inertia element including a first latching depression and a second latching depression, with the first latching depression being deeper than the second latching depression;

wherein the force transmission element is guided displaceably in the recess of the belt spindle and is capable of assuming an interlock position and a release position,

wherein the force transmission element projects further out of the recess in the interlock position than in the release position, with the result that the force transmission element and the locking flange are in engagement,

wherein the force transmission element is introduced more deeply into the recess in the release position, and the force transmission element and locking flange being out of engagement,

wherein the inertia element is held in a guide recess in the belt spindle, which is adapted to the form of the inertia element,

wherein the guide recess is larger in a longitudinal direction of the guide recess than the inertia element and provides an additional length in the longitudinal direction of the guide recess with respect to the inertia element to allow the inertia element to move in the longitudinal direction of the guide recess relative to the guide recess between the first and second positions,

wherein the first latching depression is configured such that when the inertia element is in the first position, the force transmission element engages into the first latching depression and assumes the interlock position,

wherein the second latching depression is configured such that when the inertia element is in the second position, the force transmission element assumes its release position and engages into the second latching depression,

wherein the recess of the belt spindle is a blind hole, and

wherein a length of the guide recess is at least equal to a length between the first and second latching depressions, such that if the belt spindle is abruptly set in rotational movement by the tautener drive, then the inertia element is displaced in the guide recess as a consequence of inertia from the first position to the second position to allow the force transmission element to be active only in a phase prior to belt tautening.

2. The belt retractor of claim 1 , wherein the force transmission element is movable in an axial direction in the recess of the belt spindle between the interlock and release positions.

3. The belt retractor of claim 2 , wherein the force transmission element includes a connecting pin.

4. The belt retractor of claim 3 , wherein the force transmission element further includes an end having a U-shape that is configured to engage the inertia element.

5. The belt retractor of claim 2 , wherein when the inertia element is in the first position, the force transmission element is pressed into the recess of the belt spindle to a lesser depth relative to when the inertia element is in the second position, so that the force transmission element is in engagement with the locking flange.

6. The belt retractor of claim 5 , wherein when the inertia element is in the second position, the force transmission element is out of engagement with the locking flange.

7. The belt retractor of claim 6 , wherein the first latching depression is ramp-shaped and includes a low-inclination flank and a steep flank, and wherein the low-inclination flank faces toward the second latching depression and the steep flank faces away from the second latching depression.

8. The belt retractor of claim 1 , further comprising a spring that is located in the blind hole and is configured to press the force transmission element out of the blind hole toward the locking flange.

9. A belt retractor for a safety belt, comprising:

a belt spindle for winding up and unwinding the safety belt;

a lockable locking flange connected to the belt spindle;

a force transmission element, which is held in a recess of the belt spindle and can be in engagement with the locking flange and can connect the belt spindle to the locking flange;

a tautener drive; and

an inertia element movable between a first position and a second position relative to the belt spindle, the inertia element being formed by a ring segment covering a circle angle of between 45 and 315 degrees, the inertia element including a latching depression;

wherein the force transmission element is guided displaceably in the recess of the belt spindle and is capable of assuming an interlock position and a release position,

wherein the force transmission element projects further out of the recess in the interlock position than in the release position, with the result that the force transmission element and the locking flange are in engagement,

wherein the force transmission element is introduced more deeply into the recess in the release position, and the force transmission element and locking flange being out of engagement,

wherein the inertia element is held in a guide recess in the belt spindle which is adapted to the form of the inertia element,

wherein the guide recess is larger in a longitudinal direction of the guide recess than the inertia element and provides an additional length in the longitudinal direction of the guide recess with respect to the inertia element to allow the inertia element to move in the longitudinal direction of the guide recess relative to the guide recess between the first and second position,

wherein the latching depression is configured such that when the inertia element is in the first position, the force transmission element engages into the latching depression and assumes the interlock position,

wherein the guide recess is configured such that when the inertia element is in the second position, the force transmission element assumes its release position, and

wherein the inertia element is displaced in the guide recess from the first position to the second position as a consequence of inertia, if the belt spindle is abruptly set in rotational movement by the tautener drive, in order to allow the force transmission element to be active only in a phase prior to belt tautening.

10. The belt retractor of claim 9 , wherein the inertia element is located between the belt spindle and the locking flange.

11. The belt retractor of claim 9 , wherein, when in the second position, the force transmission element is outside of the latching depression.

12. The belt retractor of claim 9 , wherein the recess of the belt spindle is a blind hole.

13. The belt retractor of claim 9 , further comprising a spring that presses the force transmission element toward the inertia element.

14. The belt retractor of claim 9 , wherein the force transmission element has a U-shaped cross section.