Magnetorheological seat belt actuator

• US 20020113424A1
• Filed: 02/20/2001
• Published: 08/22/2002
• Est. Priority Date: 02/20/2001
• Status: Active Grant

• Current Assignee: Delphi Technologies Holding S.a.r.l. (Aptiv PLC)
• Original Assignee: Delphi Technologies Holding S.a.r.l. (Aptiv PLC)
• Inventors: Kruckemeyer, William C., Oliver, Michael L., Smith, Ronald G. Jr.
• Granted Patent: US 6,805,381 B2
• Time in Patent Office: Days
• US Class Current: 280/806
• CPC Class Codes: B60R 2022/282 using fluids or vico-elastic materials
• CPC Class Codes: B60R 2022/284 using electric or magnetic braking means
• CPC Class Codes: B60R 2022/288 with means to adjust or regulate the amount of energy to be absorbed
• CPC Class Codes: B60R 22/3413 operating between belt reel and retractor frame B60R22/4676 takes precedence

Abstract

A seatbelt retractor is operably coupled to a belt dereeling retarder mechanism which utilizes a magnetorheological fluid and a coil for imposing a magnetic field on the fluid to selectively change the fluid properties and a braking or retarding effect imposed on the belt retractor during dereeling or payout of the belt. The retarder may include a piston coupled to a rotatable shaft coupled to the belt retractor reel and displacing fluid through the magnetic field in response to actuation of the belt. Alternate embodiments include a multiple disc brake coupled to the retractor reel through a gear drive speed increaser or a cylindrical housing and core member defining an annular space occupied by the magnetorheological fluid and connected to the belt retractor reel through a speed increasing gear drive.

Claims

1. In a retractor for a restraining belt for a vehicle occupant, including a reel for winding said belt thereon, a retarder mechanism operably connected to said reel and including a quantity of a magnetorheological fluid responsive to a magnetic field imposed thereon to selectively control dereeling of said belt as a consequence of forces exerted on said belt by said occupant.

2. The mechanism set forth in claim 1 wherein:

said mechanism includes a housing, including a space occupied by said quantity of said fluid and an electromagnetic coil supported on said mechanism and operable to impose a magnetic field on said fluid to selectively change properties of said fluid and a belt dereeling retarding force imposed on said retractor.

3. The mechanism set forth in claim 2 wherein:

said mechanism includes a piston in said housing and coupled to a rotatable shaft and responsive to rotation of said shaft to displace said fluid through said space to impose said magnetic field acting on said fluid while passing through said space.

4. The mechanism set forth in claim 3 wherein:

said piston is mounted in a bore in said housing and is coupled to a member to prevent rotation of said piston and said piston and said shaft include cooperating threads formed thereon to provide axial translation of said piston in response to rotation of said shaft while preventing rotation of said piston relative to said housing.

5. The mechanism set forth in claim 4 wherein:

said housing includes a first housing part supporting said piston and a second housing part supporting said coil and defining said space, and passage means formed in said housing for transferring said fluid from said first housing part to said second housing part and from said second housing part to said first housing part in response to displacement of said piston.

6. The mechanism set forth in claim 5 wherein:

said second housing part includes a generally cylindrical core member disposed therein and defining with said second housing part said space, and said coil is disposed substantially around said core member and is operable to generate a magnetic field having magnetic flux lines passing at least partially through said core member and said space.

7. The mechanism set forth in claim 2 wherein:

said mechanism includes a multiple disc brake disposed in said housing and said fluid is interposed adjacent ones of multiple discs of said brake, alternate ones of said discs are coupled to a first shaft and alternate ones of said discs are coupled to said housing, and said coil is disposed in proximity to said discs to generate a magnetic field to selectively control said properties of said fluid interposed respective ones of said discs.

8. The apparatus set forth in claim 7 wherein:

said first shaft is coupled to a second shaft through a speed increasing gear drive.

9. The mechanism set forth in claim 8 wherein:

said gear drive comprises a planetary gear drive.

10. The mechanism set forth in claim 9 wherein:

said second shaft comprises a planet gear carrier for supporting circumferentially spaced planet gears, said housing includes an internal ring gear and said first shaft includes a sun gear operably connected to said planet gears and alternate ones of said discs.

11. The mechanism set forth in claim 2 wherein:

said housing includes a generally cylindrical part defining a cylindrical bore wall and said mechanism includes a core member disposed in said housing and in spaced relationship to said bore wall to form an annular passage, and said coil is disposed in proximity to said annular passage to impose a magnetic field on said passage and on a quantity of said fluid disposed therein.

12. The mechanism set forth in claim 11 including:

a rotatable input shaft operably connected to said housing for rotating said housing with respect to said core member in response to a dereeling force exerted by said belt.

13. The mechanism set forth in claim 12 wherein:

said shaft is connected to said housing by a speed increasing gear drive.

14. The mechanism set forth in claim 13 wherein:

said gear drive is disposed in said housing.

15. The mechanism set forth in claim 12 wherein:

said shaft is coupled to said housing by a parallel shaft speed increasing gear drive.

16. The mechanism set forth in claim 15 wherein:

said gear drive is disposed exterior of said housing.

17. The mechanism set forth in claim 2 including:

a controller operably connected to said coil for conducting a selectively variable current to said coil to control properties of said fluid in relation to one of an imminent impact force on said vehicle sensed by said controller, an actual impact force sensed by said controller and an acceleration sensed by said controller.

18. The mechanism set forth in claim 17 including:

a weight sensor operably connected to said controller for sensing the weight of said occupant wearing said belt for modifying the current imposed on said coil in relation to said weight of said occupant.

20. The mechanism set forth in claim 19 including:

a rotatable input shaft operably connected to said housing for rotating said housing with respect to said core member in response to a dereeling force exerted by said belt.

21. The mechanism set forth in claim 20 wherein:

said shaft is connected to said housing by a speed increasing gear drive.

22. The mechanism set forth in claim 21 wherein:

said gear drive is disposed in said housing.

23. The mechanism set forth in claim 21 wherein:

said shaft is operably connected to said housing by a parallel shaft speed increasing gear drive.

24. The mechanism set forth in claim 23 wherein:

said gear drive is disposed exterior of said housing.

25. The mechanism set forth in claim 19 including:

a controller operably connected to said coil for conducting a selectively variable electric signal to said coil to control properties of said fluid in relation to one of an imminent impact force on said vehicle sensed by said controller, an actual impact force sensed by said controller and an acceleration sensed by said controller.

26. The mechanism set forth in claim 25 including:

a weight sensor operably connected to said controller for sensing the weight of said occupant wearing said belt for modifying said signal imposed on said coil in relation to said weight of said occupant.

19. In a retractor for a restraining belt for a vehicle occupant, including a reel for winding said belt thereon, a retarder mechanism operably connected to said reel and including a housing comprising a generally cylindrical part defining a cylindrical bore wall, a core member disposed in said housing and in spaced relationship to said bore wall to form an annular passage, an electromagnetic coil disposed in proximity to said passage to impose a magnetic field on said passage and a quantity of a magnetorheological fluid disposed in said passage and responsive to a magnetic field imposed thereon to selectively control dereeling of said belt as a consequence of forces exerted on said belt by said occupant.