OCCUPANT RESTRAINT SYSTEM

Abstract: An occupant restraint system (20) includes a folded cushion (42) having upper and lower portions (44,46), fan-folded side wall portions (72) and pleat-folded end wall portions (74). A reaction plate (80) fits between the upper wall portion (44) and the immediately adjacent distal folds (84) of the side wall portions. The distal folds (84) are clamped to the reaction plate (80) by a clamping member (88) so that initial deployment of the cushion (42) occurs laterally of the upper wall portion (44), which remains stationary. As the pressure and volume of pressure fluid increase during deployment of the cushion (42), the distal folds (84) are pulled away from the clamping member (88) and form continuations of the upper wall portion (44) which then deploys towards the occupant.

Description: This invention relates to an inflatable occupant restraint system as specified in the preamble of claim 1, for example as disclosed in US-A-4,902,036. More particularly, this invention concerns an inflatable occupant restraint system which releasably secures the inflatable cushion against initial deployment normal to, i.e., towards, the occupant and directs such initial deployment laterally of, i.e., planar to, the occupant. By directing the initial deployment of an inflatable occupant restraint cushion laterally of, i.e., planar to, the occupant, there is no engagement of the cushion and the occupant during the initial deployment stage of the cushion and such engagement is delayed to a subsequent stage of deployment of the cushion. An occupant restraint system according to the present invention is characterised by the features specified in the characterising portion of claim 1. The restraint system of this invention avoids engagement of the cushion and occupant during the initial deployment stage by releasably securing the cushion against initial deployment normal to, i.e., towards, the occupant and directing such initial deployment laterally of, i.e., planar to, the occupant. After initial deployment of the cushion has occurred, the securement is released and the cushion deploys normal to, i.e., towards, the occupant. The restraint system includes a known restraint module having a support, an enclosure mounted on the support, a folded occupant restraint cushion mounted on the support and located within the enclosure, and a gas generator or source of pressure fluid mounted on the support within the enclosure and communicating with the interior of the folded cushion. The cushion is folded to provide a substantially planar upper wall portion of substantially rectangular shape, a lower wall portion, fan-folded longer side wall portions, and pleat-folded end wall portions which are turned under the fan-folded side wall portions. The side wall and end wall portions connect the upper and lower wall portions. Such a restraint module is shown and described in part in co-pending European application EP-A-0 370 613. The restraint system of this invention additionally includes a planar reaction member of the general size of the upper wall portion of the cushion and located within the folded cushion between the upper wall portion and the first, distal, inwardly-directed folds of the fan-folded side wall portions. The reaction member is mounted to the support. A clamping securement member clamps the first, distal folds of the fan-folded side wall portions to the lower side of the reaction member. During initial inflation and deployment of the cushion, the reaction member blocks impingement of the pressure fluid from the gas generator on the upper wall portion of the cushion. The clamping of the first, distal folds of the fan-folded side wall portions of the cushion to the lower side of the reaction member blocks the pressure fluid from flowing between said folds and around the sides of the reaction member to the upper side thereof and underneath the upper wall portion of the cushion. The pleat-folded end wall portions provide a tortuous path and effectively block the pressure fluid from flowing around the ends of the reaction member to the upper side thereof. Thus, no pressure fluid can impinge on the upper wall portion and the upper wall portion remains stationary during the initial stage of deployment of the cushion. The impingement of the pressure fluid against the fan-folded side wall portions of the cushion, other than the first, distal folds thereof, initiates deployment of the cushion laterally of, i.e., planar to, the occupant through outwardly-opening separable flaps in the side walls of the enclosure opposite the side wall portions of the cushion. As the pressure and volume of the pressure fluid build up within the cushion, the fan-folded side wall portions continue to unfold. When the volume and pressure of the pressure fluid reach a level sufficient to overcome the clamping force of the clamping member, the first, distal folds of the cushion are pulled outwardly and away from the lower side of the reaction member to permit the pressure fluid to impinge on the upper wall portion of the cushion around the reaction member as the distal folds unfold relative to the side and upper wall portions. The impingement of the pressure fluid on the upper wall portion initiates deployment of the cushion through outwardly-opening separable flaps in the upper wall of the enclosure as the pleat-folded end wall portions unfold, to provide the upper, outer wall of the cushion which moves normal to, i.e., towards, the occupant. The subsequent engagement of the occupant and said upper, outer wall during such movement provides the occupant restraint. The primary feature of this invention is that it provides an occupant restraint system which releasably secures an inflatable occupant restraint cushion against movement normal to, i.e., towards, an occupant during the initial stage of deployment of the cushion. Another feature is that the cushion is deployed in directions laterally of, i.e., planar to, the occupant during the initial deployment stage. A further feature is that the wall of the cushion engageable by the occupant is releasably secured against movement normal to, i.e., towards, the occupant during the initial deployment stage. Yet another feature is that said wall of the cushion is released when the volume and pressure of the inflating pressure fluid build up to a predetermined level. Yet a further feature is that the cushion is folded to provide an upper wall portion, fan-folded side wall portions and pleat-folded end wall portions, with the distal folds of the fan-folded side wall portions being releasably clamped to a reaction member. Still another feature is that the reaction member is planar, of the general size of the upper wall portion of the folded cushion, and has its upper side engaging said upper wall portion and its lower side clamped to the distal folds of the fan-folded side wall portions. Still a further feature is that the reaction member is mounted to the support for the cushion. Yet another feature is that the clamping force is provided by a clamping member mounted to the lower side of the reaction member. The invention and how it may be performed are hereinafter particularly described with reference to the accompanying drawings, in which: Figure 1 is a top, plan view of an occupant restraint system according to this invention; Figure 2 is an enlarged sectional view taken along line 2-2 of Figure 1; Figure 3 is a sectional view taken along line 3-3 of Figure 2; and Figure 4 is a partially broken-away perspective view of a portion of Figure 2. Referring now to Figures 1 to 3 of the accompanying drawings, an occupant restraint system 20 is shown mounted in a conventional manner to a hub portion 22 of a vehicle steering wheel 24. The hub portion includes a splined bushing 26 which receives an upper splined end of a vehicle steering shaft 28 and is bolted thereto at 30 to secure the steering wheel to the vehicle steering system. A substantially rectangularly-shaped support plate 32, Figure 4, has a central, circular opening 34. A flange 36 of a conventional inflator 38 seats against a lower side of the plate 32 and is secured thereto in a conventional manner. An upper outlet portion 40 of the inflator projects through the plate 32 and into the interior of a folded inflatable driver restraint cushion 42. The cushion 42 includes upper and lower circular members 44 and 46 which are secured together at their circular edge portions. The upper cushion member 44 provides the impact surface of the cushion for the driver when the cushion is inflated, and the lower cushion member 46 has a central opening 48 which receives the upper outlet portion 40 of the gas generator therethrough. A ring 50 is fastened at 52 to the plate 32 around the opening 34 therein to clamp the cushion member 46 to the plate 32 around the opening 48 therethrough. The inflator 38 is a gas generator which is electrically actuated from a conventional electrical power source when acceleration or velocity or other type sensors sense the impact of the vehicle with an obstacle or the possibility or probability of such an impact. Such sensors and the circuits connecting the sensors to a power source are well-known in the art. Likewise, inflators of the gas-generating type are also well-known in the art. A container 54 for the cushion 42 is formed of plastics material and has a substantially box-like, rectangular shape. The container 54 houses the folded cushion 42 and has a flange 56 which underlies the plate 32 and has lateral flange segments 58 therealong. An outer decorative cover 60 of plastics material is of the same general shape as the container 54. The cover 60 has a flange 62 which overlies the flange 56 of the container. A retainer 64 overlies the flanges 56 and 62 and is fastened at 66 to the support plate 32 to secure the container 54 and cover 60 to the support plate 32. The cover 60 is provided with a moulded-in line 68 in its upper wall which also extends along the longer side walls of the cover 60 to provide the upper wall with oppositely-opening separable flaps 69 and provide the longer side walls with oppositely-opening separable flaps 70. The container 54 is provided with lines of perforations which provide like flaps in the upper and longer side walls thereof. The details of the container 54 and the cover 60, and the manner in which each separates into flaps during deployment of the cushion 42 are disclosed in the aforenoted European application EP-A-0 370 613. Such disclosure is incorporated herein by reference. The plate 32 thus mounts the inflator 38, the cushion 42, the container 54, and the cover 60 to provide the modular restraint system 20. The manner in which the cushion 42 is folded is disclosed in the aforenoted European application EP-A-0 370 613. Generally, the upper and lower circular cushion members 44 and 46 of the cushion are laid flat with respect to each other, then diametrically-opposite chordal portions of the cushion members are fan-folded with respect to each other to provide a series of fan folds 72, (see Figures 3 and 4). Then, each end of the chordal portions and fan folds is pleat-folded to provide a series of folds 74, (see Figures 2 and 4). The folds 74 as a unit are then tucked under or folded under respective ends of a last, proximal fold 76 of folds 72 rather than extending from the folds 72 as shown in the aforenoted European application EP-A-0 370 613. The folded cushion thus has fan-folded side wall portions and pleat-folded end wall portions. A reaction plate member 80 of the general size of an upper wall portion 82 of the folded cushion is located between said upper wall portion and the first, distal folds 84 of the folds 72 of the fan-folded side wall portions. The reaction member 80 is generally planar and formed of metal or other material which will withstand the temperature and pressure of the gases generated by the inflator 38. The reaction member 80 is located within the folded cushion by a pair of pin struts 86 which have their lower ends secured to the ring 50 and their upper ends secured to the reaction member 80. A clamping member 88 of plastics material is fastened at 90 to the underside of the reaction member 80 along the longitudinal centre-line of both members. The clamping member is of a smaller size than the reaction member and has its unsecured longitudinal portions underlying and clamping the first, distal folds 84 to the underside of the reaction member 80 with a predetermined force. The reaction member 80, the clamping member 88, the struts 86 and the ring 50 are assembled as a unit and then inserted into the interior of the folded cushion through the opening 48 in the lower cushion member 46. The ring 50 is then attached around the opening 48 to the plate 32 co-axial with the plate opening 34, and then the inflator 38 is fixed within the plate opening 34 to provide the assembly shown in Figure 4. This assembly is then housed within the container 54 and the cover 60 with the fan-folded side wall portions opposite the longer side walls and the pleat-folded end portions opposite the shorter side walls of the container 54 and the cover 60. The completed occupant restraint system is assembled in overlying relationship to the hub portion 22 by fasteners, not shown, which extend upwardly through openings in the hub portion and into tapped struts 92 which are secured to embossments 94 of the plate 32. When the inflator receives an appropriate signal, the inflator generates gas or pressure fluid which is fed into the interior of the folded cushion 42 through the upper outlet portion 40 of the inflator. The pressure fluid initiates unfolding of the folds 72 of the fan-folded side wall portions of the cushion 42 to initiate deployment of the cushion through the separable flaps 70 in the longer side walls of the container 54 and cover 60. The upper wall portion 82 of the cushion 42 remains stationary since the clamping of the first, distal folds 84 to the reaction member 80 by the clamping member 88 prevents the pressure fluid from flowing around the sides of the reaction member 80 and impinging on said upper wall portion 82. The tortuous paths provided by the folds 74 of the pleat-folded end wall portions prevent the pressure fluid from flowing around the ends of the reaction member 80 and impinging on the upper wall portion 82 of the cushion. Thus, the upper wall portion 82 of the cushion remains stationary and the cushion is initially deployed laterally of the occupant through the longer side walls of the container 54 and cover 60 through the separable flaps 70. As the volume and pressure of the pressure fluid rise within the initially deploying cushion 42, the first, distal folds 84 are pulled outwardly from between the clamping member 88 and the reaction member 80 and begin to unfold into continuations of the other folds 72 and the upper wall portion 82 of the cushion as the pressure fluid impinges on the folds 84 and the upper wall portion 82. The unfolding of the folds 84 and the impingement of the pressure fluid on the upper wall portion 82 initiate deployment of the cushion normal to the occupant through the upper walls of the container and cover as the separable flaps 69 separate and open outwardly and oppositely of each other. The deployment of the cushion normal to, i.e., towards, the occupant is delayed and occurs subsequent to the deployment of the cushion laterally of, i.e., planar to, the occupant. The engagement of the cushion and occupant as the cushion deploys normal to, i.e., towards, the occupant provides the occupant restraint. The securing force of the clamping member 88 can be varied as desired in order to predetermine the delay in deployment of the cushion normal to, i.e., towards, the occupant. The aforenoted European application EP-A-0 370 613 shows various embodiments of separable flaps in the upper and longer side walls of the container and cover. The restraint system of this invention can be used with each of these embodiments. Thus, this invention provides an inflatable occupant restraint system which releasably secures an inflatable occupant restraint cushion against deployment normal to, i.e., towards, the occupant and directs such initial deployment laterally of, i.e., planar to, the occupant. The securement of the cushion is released at a predetermined time to permit deployment of the cushion normal to, i.e., towards, the occupant, so as to delay the engagement of the occupant and cushion until after initial deployment of the cushion.

Claims: An occupant restraint system (20) comprising: a support (32), an occupant restraint cushion (42) including a lower wall portion (46) mounted on the support (32), an upper wall portion (44) spaced from the support (32), and folded side wall portions (72) interconnecting the upper and lower wall portions (44,46), a source (38) of pressure fluid mounted on the support (32) and opening to the interior of the cushion through the lower wall portion (46) to deploy the cushion (42), and a pressure fluid reaction means (80) preventing direct impingement of the pressure fluid against an inner surface of the cushion (42), characterised in that the pressure fluid reaction means (80) covers the upper wall portion (44) to prevent impingement of the pressure fluid thereagainst; there are support means (86) mounting the reaction means (80) on the support (32) in overlying spaced relationship to the source (38) of pressure fluid; and there are retaining means (72,88) releasably sealing the space between the reaction means (80) and the upper wall portion (44) of the cushion (42) against entry of the pressure fluid during initial deployment of the cushion (42), so as to restrict such initial deployment to deployment laterally of the reaction means (80) by unfolding of the folded side wall portions (72) and end wall portions (74) thereof, whilst maintaining the upper wall portion (44) substantially stationary. An occupant restraint system (20) according to claim 1, in which the reaction means is a substantially planar member (80) substantially the same size as the upper wall portion (44). An occupant restraint system (20) according to claim 1 or 2, in which the source of pressure fluid is an inflator (38) mounted on the support (32), and the support means comprise struts (86) extending between the reaction means (80) and the support (32) adjacent the inflator (38). An occupant restraint system (20) according to claim 1, in which the reaction means includes a planar member (80) substantially the same size as the upper wall portion (44) which is located between the upper wall portion (44) and distal portions (84) of the folded side wall portion (72) and the end wall portion (74) of the cushion (42). An occupant restraint system (20) according to claim 1, in which the restraint means includes a planar member (80) having the edge portions thereof sealed to the upper wall portion (44) by the retaining means (72,88). An occupant restraint system (20) according to claim 1, in which the support (32) has an opening (34) therein; the source (38) of pressure fluid extends through the support opening (34); the lower wall portion (46) is mounted on the support (32) adjacent the opening (34) therein; the side wall portions are fan-folded side wall portions (72) connecting the upper and lower wall portions (44,46) and include a number of fan folds; the reaction means is a reaction plate (80) located between the upper wall portion (44) and the distal folds (84) of the side wall portions; the support means (86) extends between the plate (80) and the support (32); and the retaining means includes a clamping member (88) mounted to the plate (80) which clamps the distal folds (84) of the side wall portions to the plate (80) to block the flow of pressure fluid around the reaction plate (80) to the upper wall portion (44) of the cushion (42) and maintains said upper wall portion (44) stationary during the initial deployment of the cushion (42). An occupant restraint system according to claim 6, in which the end wall portion comprises pleat-folded end wall portions (74) folded under the upper wall portion (44) as a unit; the reaction plate (80) is substantially the same size as the upper wall portion (44) and is located between the upper wall portion (44), the pleat-folded end wall portions (74), and the distal folds (84) of the side wall portions; and the pleat-folded end wall portions (74) provide tortuous paths blocking the flow of pressure fluid around the ends of the reaction plate (80) so that the upper wall portion (44) remains stationary during the initial deployment of the cushion (42).

Inventors: MILLER, GREGORY ALLEN
Applicants: GENERAL MOTORS CORPORATION
Application year: 1991
Main classification: B60R21
IPC codes: B60R21