Gas generator assembly

• US 7,789,018 B2
• Filed: 04/01/2005
• Issued: 09/07/2010
• Est. Priority Date: 04/02/2004
• Status: Active Grant

• Current Assignee: Joyson Safety Systems Acquisition, LLC
• Original Assignee: Automotive Systems Laboratory, Incorporated (Ningbo Junsheng Investment Group Co., Ltd.)
• Inventors: Burns, Sean P.
• Primary Examiner(s): HAYES, BRET C
• Application Number:
  US11/096,887
• Publication Number:
  US 20050218637A1
• Time in Patent Office: 1,985 Days
• Field of Search: 102288-291, 102/285, 102/286, 280/728.1
• US Class Current: 102/288
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder
• CPC Class Codes: F02K 9/20 of the external-burning type
• CPC Class Codes: F42B 5/16 characterised by composition or physical dimensions or form of propellant charge, with or without projectile, or powder chemical composition C06B; F42B5/24 takes precedence

Abstract

A gas generant tablet (24) for use in a linear inflator (10). The tablet (24) includes a body portion (102) having a first end (104), a second end (106), and a longitudinal axis (T). A first projection (108) extends from the tablet first end (104) in a first direction, with at least a portion of the first projection (108) extending non-orthogonally with respect to the tablet longitudinal axis (T). A second projection (112) extends from the tablet second end (106) in a second direction generally opposite the first direction. At least a portion of the second projection (112) extends non-orthogonally with respect to the tablet longitudinal axis (T). The tablet (24) is shaped such that a cavity (25) is formed between adjacent tablets (24) when the tablets are stacked within a combustion chamber of the inflator (10). Also disclosed is an inflator (10) for use in an inflatable vehicle occupant protection system (200). The inflator (10) includes a longitudinal enclosure (22) having a substantially uniform cross-sectional area along at least a portion of the enclosure. The enclosure (22) defines an interior cavity (22c) for containing a quantity of a gas generant composition therein, and includes a plurality of apertures (40) formed therealong to enable fluid communication between the enclosure interior cavity (22c) and an exterior of the enclosure. A plurality of gas generant tablets (24) is stacked along the enclosure (22), the tablets being shaped such that a cavity (25) is provided between adjacent tablets (24) when the tablets are stacked within the enclosure (22).

Claims

1. A gas generant tablet comprising:

a body portion having a first end, a second end, and a longitudinal axis;

a first projection extending from the first end in a first direction, at least a portion of the first projection extending non-orthogonally with respect to the longitudinal axis;

a second projection extending from the second end in a second direction generally opposite the first direction, at least a portion of the second projection extending non-orthogonally with respect to the longitudinal axis; and

a land portion extending from a periphery of the body portion toward the longitudinal axis to substantially circumscribe at least one of the first projection and the second projection,

wherein at least one of the first projection and the second projection is substantially spherical and covers a majority of the periphery.

2. The gas generant tablet of claim 1 wherein the dimensions of the first projection are substantially the same as the dimensions of the second projection.

3. The gas generant tablet of claim 1 wherein at least one of the first projection and the second projection is spherical.

4. The gas generant tablet of claim 1 further comprising a land portion extending from a periphery of the body portion toward the longitudinal axis to circumscribe at least one of the first projection and the second projection.

5. The gas generant tablet of claim 1 wherein the land portion extends along a plane substantially perpendicular to the longitudinal axis.

6. The gas generant tablet of claim 1 wherein a width of the land portion between the periphery of the body portion and the at least one of the first projection and the second projection is substantially constant along the extent of the land portion.

7. The gas generant tablet of claim 1 wherein at least one of the first projection and the second projection is convex.

8. The gas generant tablet of claim 1 wherein the body portion is substantially cylindrical.

9. The gas generant tablet of claim 1 wherein the body portion is substantially cylindrical and has a diameter,

a height of the gas generant tablet is defined as a distance along the longitudinal axis between a point at which the longitudinal axis intersects the first projection and a point at which the longitudinal axis intersects the second projection;

and

the ratio of the diameter to the height is greater than 1.0.

10. The gas generant tablet of claim 9 wherein and the ratio of the diameter to the height is greater than 1.3.

11. An inflator for use in an inflatable vehicle occupant protection system, the inflator comprising:

a longitudinal enclosure having a substantially uniform cross-sectional area along at least a portion of the enclosure, the at least a portion of the enclosure defining an interior cavity for containing a quantity of a gas generant composition therein, the at least a portion of the enclosure including a plurality of apertures formed therealong to enable fluid communication between the enclosure interior cavity and an exterior of the enclosure; and

a plurality of gas generant tablets stacked along the at least a portion of the enclosure, each of the tablets having a body portion at least one substantially spherical projection extending from the body portion, and

a land portion from a periphery of the body portion toward the longitudinal axis to substantially circumscribe the substantially spherical projection wherein the at least one substantially spherical projection covers a majority of the periphery.

12. The inflator of claim 11 wherein the body portion of each tablet has a first end, a second end, and a longitudinal axis and wherein each of the tablets includes:

a first projection extending from the first end in a first direction, at least a portion of the first projection extending non-orthogonally with respect to the longitudinal axis; and

a second projection extending from the second end in a second direction generally opposite the first direction, at least a portion of the second projection extending non-orthogonally with respect to the longitudinal axis.

13. The inflator of claim 12 wherein the dimensions of the first projection are substantially the same as the dimensions of the second projection.

14. The inflator of claim 12 wherein the ratio of a total volume of the plurality of gas generant tablets stacked along the at least a portion of the enclosure to a total volume of the interior cavity of the at least a portion of the enclosure is in the range 0.35-0.65.

15. The inflator of claim 14 wherein a ratio of a total volume of the plurality of gas generant tablets stacked along the at least a portion of the enclosure to a total volume of the interior cavity of the at least a portion of the enclosure is in the range 0.45-0.55.

16. The inflator of claim 12 wherein the enclosure is substantially cylindrical and has an inner diameter;

the body portion of at least one of the gas generant tablets terminates at a first edge proximate the tablet first end;

the body portion of the at least one of the gas generant tablets terminates at a second edge proximate the tablet second end;

a line extending from a first point along the first edge through the longitudinal axis intersects a second point along the first edge;

a line from the second point along the first edge extending substantially parallel with the longitudinal axis intersects a point along the second edge;

a diagonal dimension of a gas generant tablet is defined by a distance between the first point along the first edge and the point along the second edge; and

wherein the diagonal dimension is less than or equal to the enclosure inner diameter,

and wherein the difference between the inner diameter and the diagonal dimension is approximately 0.52 millimeter.

17. The inflator of claim 16 wherein the difference between the inner diameter and the diagonal dimension is approximately 0.52 millimeter.

18. The inflator of claim 11 wherein the enclosure is substantially cylindrical and has an inner diameter, the tablet body portion is substantially cylindrical and has a diameter, and wherein the difference between the inner diameter and the tablet body diameter is approximately 0.70 millimeter.

19. The inflator of claim 11 wherein the enclosure is substantially cylindrical and has an inner diameter;

the body portion is substantially cylindrical and has an outer diameter;

a height dimension of a gas generant tablet is defined as a distance along the longitudinal axis between a point at which the longitudinal axis intersects the first projection and a point at which the longitudinal axis intersects the second projection; and

the difference between the inner diameter and twice the height dimension is approximately 0.64 millimeter.

20. A vehicle occupant restraint system comprising:

an airbag system having at least one airbag and an inflator coupled to the airbag so as to enable fluid communication with an interior of the airbag upon activation of the inflator, the inflator including;

a longitudinal enclosure extending along at least a portion of the housing interior, the enclosure having a substantially uniform cross-sectional area along at least a portion of the enclosure, the at least a portion of the enclosure defining an interior cavity for containing a quantity of a gas generant composition therein, the at least a portion of the enclosure including a plurality of apertures formed therealong to enable fluid communication between the enclosure interior cavity and an exterior of the enclosure; and

a plurality of gas generant tablets stacked along the at least a portion of the enclosure, each of the tablets having a body portion and at least one substantially spherical projection extending from the body portion and a land portion extending from a periphery of the body portion toward the longitudinal axis to substantially circumscribe the substantially spherical projection wherein the at least one substantially spherical projection covers a majority of the periphery.