Seat belt retractor with overmolded inertia sensor mass

1. A seat belt retractor comprising:

a seat belt retractor;

an actuator for unlocking and locking the seat belt retractor;

a sensor housing;

an inertial sensor disposed in and movable relative to the sensor housing for detecting changes in vehicle acceleration, the inertial sensor interacting with the actuator to lock and unlock the seat belt retractor; and

the inertial sensor having a wide portion and a narrow portion, the inertial sensor comprising an inertial sensor mass having a body partially embedded in the wide portion in an elastomeric material, the body of the inertial sensor mass having a greater density than the elastomeric material, a first portion of the inertial sensor mass comprises a portion of an exterior surface of the body that is free of the elastomeric material contacts the actuator at zero acceleration at a first portion, wherein the elastomeric material substantially surrounds an exterior circumferential surface of the wide portion such that the elastomeric material in which the wide portion is embedded contacts the sensor housing when the inertial sensor tips in response to changes in vehicle acceleration.

2. The seat belt retractor of claim 1 wherein the inertial sensor has a second portion supporting the inertial sensor mass on the sensor housing, the elastomeric material disposed between the first portion and the second portion.

3. The seat belt retractor of claim 1 wherein the elastomeric material additionally has filler particles, the filler particles having a greater density than the elastomeric material.

4. The seat belt retractor of claim 2 wherein the second portion comprises the elastomeric material supporting the inertial sensor mass on the sensor housing.

5. A seatbelt retractor assembly comprising:

an inertial sensor mass for detecting changes in vehicle speed;

a housing for receiving said inertial sensor mass, said inertial sensor mass movable relative to said housing;

said inertial sensor mass having a wide portion and a narrow portion, said inertial sensor mass having a body partially embedded in the wide portion in an elastomeric material, first protruding elastomeric members and second protruding elastomeric members extending from the wide portion of said inertial sensor mass, said first protruding elastomeric members spaced from said second protruding elastomeric members by gaps, said first and second protruding elastomeric members movable relative to said inertial sensor mass, and at least one of said first and second protruding elastomeric members contacts the housing when the inertial sensor mass tips in response to changes in vehicle acceleration; and

a first portion of the inertial sensor mass comprises a portion of an exterior surface of the body that is free of the elastomeric material and a seatbelt retractor mechanism is linked to said inertial sensor via said first portion of the inertial sensor mass.

6. The seatbelt retractor assembly of claim 5 wherein said protruding elastomeric members are movable relative to said second protruding elastomeric members.

7. The seatbelt retractor of claim 5 wherein said housing has at least one annular bumper protruding from an internal surface of the housing, and at least one of said first and second protruding elastomeric members contacts an annular bumper when the inertial sensor mass tips in response to changes in vehicle acceleration.

8. The seatbelt retractor of claim 5 wherein said housing has a plurality of vertical ridges protruding from an internal surface of the housing, and at least one of said first and second protruding elastomeric members contacts a vertical ridge when the inertial sensor mass tips in response to changes in vehicle acceleration.

9. A seatbelt retractor assembly comprising:

an inertial sensor mass for detecting changes in vehicle speed;

a housing for receiving the inertial sensor mass, the housing has a plurality of vertical ridges protruding from an internal surface of the housing, the inertial sensor mass movable relative to the housing;

the inertial sensor mass having a wide portion and a narrow portion, the inertial sensor mass having a body partially embedded in the wide portion in an elastomeric material, the body of the inertial sensor mass having a greater density than the elastomeric material, first vertically extending protruding elastomeric members and second vertically extending protruding elastomeric members extending from the wide portion of the inertial sensor mass, the first vertically extending protruding elastomeric members spaced from the second vertically extending protruding elastomeric members by gaps, the first and second vertically extending protruding elastomeric members movable relative to the inertial sensor mass, and at least one of the first and second vertically extending protruding elastomeric members contacts the vertical ridges on the internal surface of the housing when the inertial sensor tips in response to changes in vehicle acceleration; and

a first portion of the inertial sensor mass comprises a portion of an exterior surface of the body that is free of the elastomeric material and a seatbelt retractor mechanism is linked to said inertial sensor via the first portion of the inertial sensor mass.

10. The seat belt retractor assembly of claim 9 wherein the elastomeric material additionally has filler particles, the filler particles having a greater density than the elastomeric material.