Load limiting seatbelt retractor
A seatbelt retractor includes a spool, a piston, a cylinder, a ring, and a valve. The spool is rotatably connected with a base by the piston and the cylinder. The piston is fixed to one of the base and the spool. The cylinder receives the piston and is fixed to the other of the base and the spool. The piston and the cylinder define a first chamber. The ring is sealed against the cylinder and defines a second chamber connected with the first chamber by an aperture. The valve is disposed across the aperture.
1. A seatbelt retractor comprising:
a spool rotatably connected with a base by a piston and a cylinder;
the piston fixed to one of the base and the spool;
the cylinder receiving the piston, fixed to the other of the base and the spool, defining a first chamber; and
a ring sealed against the cylinder and defining a second chamber connected with the first chamber by an aperture; and
a valve disposed across the aperture.
2. The seatbelt retractor of claim 1 , further comprising:
a housing with the spool rotatably coupled thereto for relative rotation of the spool thereto about an axis of rotation defined by the spool; and
a base lock disposed between the base and the housing, the base lock in a first condition fixing the base to the housing.
3. The seatbelt retractor of claim 2 , the base lock further comprising:
a plurality of clutching teeth disposed on an outer circumference of the base for rotation therewith; and
an engagement tooth connected to the housing, the engagement tooth in the first condition being in engagement with the clutching teeth and the engagement tooth in a second condition being not in engagement with the clutching teeth,
wherein engagement of the engagement tooth with the clutching teeth rotatably fixes the cylinder to the base.
4. The seatbelt retractor of claim 1 , wherein the piston has piston threads and the cylinder includes a bore receiving the piston and cylinder threads are inside the bore and the piston threads and the cylinder threads are in threaded engagement with each other.
5. The seatbelt retractor of claim 1 , wherein the cylinder is connected to the base and the piston is connected to the spool.
6. The seatbelt retractor of claim 1 , wherein the ring is divided into a plurality of secondary chambers, each with an aperture connecting to the first chamber and a valve disposed across the aperture.
7. The seatbelt retractor of claim 6 , wherein the plurality of secondary chambers is at least three.
8. The seatbelt retractor of claim 6 , wherein the valves are rupturable pressure relief valves having a rupture strength corresponding to a predetermined seatbelt tension force.
9. The seatbelt retractor of claim 6 , wherein the valves are pressure relief valves and each has a predetermined pressure relief value with its pressure relief value selected to correspond to an associated predetermined seatbelt tension force, and the predetermined seatbelt tension forces are not equal.
10. The seatbelt retractor of claim 9 , wherein a flow area of the apertures and the pressure relief value of the valves associated with the apertures vary inversely, with the flow area of the apertures decreasing as the pressure relief value of the valves increases.
11. A seatbelt retractor comprising:
a spool rotatably connected with a base by an energy absorber;
a housing with the spool rotatably coupled thereto for relative rotation of the spool thereto about an axis of rotation defined by the spool;
a base lock disposed between the base and the housing, the base lock in a first condition fixing the base to the housing; and
the energy absorber including:
a piston fixed to one of the base and the spool,
a cylinder receiving the piston and fixed to the other of the base and the spool and defining a first chamber, and
a ring sealed against the cylinder and defining a second chamber connected with the first chamber by an aperture; and
a valve disposed across the aperture.
12. The seatbelt retractor of claim 11 , wherein the base lock includes:
a plurality of clutching teeth disposed on an outer circumference of the base for rotation therewith; and
an engagement tooth connected to the housing, the engagement tooth in the first condition being in engagement with the clutching teeth and the engagement tooth in a second condition being not in engagement with the clutching teeth,
wherein engagement of the engagement tooth with the clutching teeth rotatably fixes the cylinder to the base.
13. The seatbelt retractor of claim 11 , wherein the piston has piston threads and the cylinder includes a bore receiving the piston and cylinder threads are inside the bore and the piston threads and the cylinder threads are in threaded engagement with each other.
14. The seatbelt retractor of claim 11 , wherein the ring is divided into a plurality of secondary chambers, each with an aperture connecting to the first chamber and a valve disposed across the aperture.
15. The seatbelt retractor of claim 14 , wherein the plurality of secondary chambers is at least three.
16. The seatbelt retractor of claim 14 , wherein the valves are rupturable pressure relief valves having a rupture strength corresponding to a predetermined seatbelt tension force.
17. The seatbelt retractor of claim 14 , wherein the valves are pressure relief valves and each has a predetermined pressure relief value with its pressure relief value selected to correspond to an associated predetermined seatbelt tension force, and the predetermined seatbelt tension forces are not equal.
18. The seatbelt retractor of claim 17 , wherein a flow area of the apertures and the pressure relief value of the valves associated with the apertures vary inversely, with the flow area of the apertures decreasing as the pressure relief value of the valves increases.
19. The seatbelt retractor of claim 11 , wherein the cylinder is connected to the base and the piston is connected to the spool.
20. The seatbelt retractor of claim 19 , wherein an end cap is rotatably fixed to the spool and to an end of the piston, and the end cap is rotatably supported by a spring cover.