Occupant protection system

An occupant protection system for protecting a vehicle occupant sitting in a seat includes a seatbelt that includes a lap belt for arresting the pelvis of the occupant, and an airbag disposed in the lap belt. The airbag is coupled to the lap belt in such a manner as to be movable relative to the lap belt in a left and right direction, and includes a main inflatable portion that is deployable in front of upper body of the occupant, and a positioning inflatable portion that protrudes from a lower end region of the main inflatable portion. The positioning inflatable portion includes a contact surface that contacts and is supported by an environmental member which is disposed in a circumference of the lap belt at airbag deployment, whereby helps align a center in the left and right direction of the main inflatable portion generally with that of the upper body.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority from Japanese Patent Application No. 2019-178713 of Tanaka et al., filed on Sep. 30, 2019, the entire disclosure of which is incorporated herein by reference.

BACKGROUND

1. Technical Field

The present disclosure relates to an occupant protection system for protecting a vehicle occupant sitting in a seat.

2. Description of Related Art

JP 2010-036665 A discloses, inFIGS.3and4, an occupant protection system for protecting a vehicle occupant sitting in a seat. The system includes a four-point seatbelt and two main airbags which are respectively stored in two shoulder belts of the seatbelt. The main airbags are configured to protrude from the shoulder belts and be deployed over the front surface of the upper body of the occupant. This occupant protection system further includes two position-keeping airbags which are configured to be inflated and deployed beneath the main airbags, respectively, on a side towards the door and on a side towards the center console for keeping the positions of the main airbags with respect to the occupant. The position-keeping airbags are configured to receive a supply of inflation gas from an inflator separate from that for inflating the main airbags. That is, the occupant protection system disclosed in the above-described literature has a complicated structure.

SUMMARY

An exemplary embodiment of the present disclosure relates to an occupant protection system for protecting an occupant sitting in a seat of a vehicle, the occupant protection system including: a three-point seatbelt that includes a lap belt which is configured to arrest a pelvic region of the occupant; an inflator; and an airbag that is formed of a sheet material having flexibility and stored in a storage in the lap belt in a folded form. The airbag is coupled to the lap belt in such a manner as to be movable in a left and right direction with respect to the lap belt, and configured to be inflated and deployed upward from the storage when fed with an inflation gas from the inflator. The airbag includes: a main inflatable portion that is configured to be deployed in front of an upper body of the occupant for protecting the upper body; and a positioning inflatable portion that protrudes at least from a first end in a left and right direction of a lower end region of the main inflatable portion, the positioning inflatable portion including a contact surface that contacts and is supported by an environmental member which is disposed in a circumference of the lap belt at airbag deployment, the positioning inflatable portion helping align a center in the left and right direction of the main inflatable portion generally with a center in a left and right direction of the upper body by making the contact surface butt the environmental member at airbag deployment.

DETAILED DESCRIPTION

Exemplary embodiments of the present disclosure are described below with reference to the accompanying drawings. However, the invention is not limited to the embodiments disclosed herein. All modifications within the appended claims and equivalents relative thereto are intended to be encompassed in the scope of the claims.

As shown inFIGS.1to3, an occupant protection system S is installed in a seat1of a vehicle, and includes a seatbelt7, an airbag25and an inflator17. The seat1includes a seatback2and a seat portion3.

Unless otherwise specified, front and back, up and down, and left and right directions in this specification correspond to front and back, up and down, and left and right directions of the seat1.

The seatbelt7is a three-point seatbelt, and includes a belt body8for restraining an occupant MP sitting in the seat1, a tongue plate12which is attached to the belt body8, and a buckle13for engagement with the tongue plate12. A not-shown retractor is located inside of the seatback2, and the belt body8is retained by a reel shaft of the retractor by the first end, and retained, by the second end, by an anchor member14(FIGS.1and2) located in a left side of a rear end3bregion of the seat portion3. More specifically, the belt body8is arranged to protrude from a left upper end portion of the seatback2such that a later-described lap belt10, which includes an airbag25as will be described below, is exposed on a front surface of the backrest2when not worn by the occupant, as can be seen inFIGS.1and2. The belt body8includes a lap belt10, and a shoulder belt9which is stored inside of the seatback2. When the occupant pulls the belt body8from the reel shaft and buckles the tongue plate12in the buckle13, the lap belt10extends generally in a left and right direction between the anchor member14and buckle13and restrains the lower body MD (pelvic region MW) of the occupant MP while the shoulder belt9extends diagonally from the left upper end portion of the seatback2to the buckle13and restrains the upper body MU (shoulder to thorax) of the occupant MP, as can be seen inFIG.3. The belt body8is configured to be pulled out according to the physical size of the occupant MP when buckled in. In this specific embodiment, the lap belt10is configured to be exposed on the front surface of the backrest2in a left edge region2aof the backrest2and extend generally in an up and down direction, when not worn by the occupant, as can be seen inFIG.1.

The inflator17is disposed farther downward than a seat surface3aof the seat1. In this specific embodiment, as can be seen inFIG.2, the inflator17includes a generally cylindrical inflator body18which is disposed beneath the seat portion3and in a vicinity of the back of the seat1in such a manner as to extend generally in the left and right direction, though not depicted in detail, and a pipe19which extends from the inflator body18for feeding the airbag25with an inflation gas. The pipe19is made from metal and extends from the inflator body18. The leading end of the pipe19is located in a vicinity of the border between the seat portion3and seatback2in the left side of the seat1, and is connected with a later-described conduit portion52of the airbag25with a clamp20.

The airbag25is disposed in the lap belt10region in a folded form57. The folded form57is a form of a later-described bag body26as folded in an elongated shape. More particularly, the bag body26in the folded form57and the conduit portion52which extends from the bag body26are stacked on the lap belt10, as can be seen inFIG.3. That is, in the not-worn state as can be seen inFIG.1, the bag body26in the folded form57and the conduit portion52are disposed on a back side of the lap belt10to face the seatback2. In this specific embodiment, the lap belt10, the bag body26in the folded form57and the conduit portion52are wrapped by a cover22which is configured to break at airbag deployment as can be seen inFIG.3, thus the bag body26and the conduit portion52are integrated with the lap belt10. That is, a void space formed between the lap belt10and the cover22constitutes a storage of the airbag25.

The airbag25is coupled to the lap belt10in such a manner as to be movable relative to the lap belt10in a left and right direction. As can be seen inFIGS.4to9, the airbag25includes a bag body26, a conduit portion52which is connected with the inflator17for feeding the bag body26with an inflation gas, and a mounting portion55which attaches the bag body26to the lap belt10. The airbag25is made of a sheet material having flexibility. In this specific embodiment, the airbag25is made of a fabric woven with polyester yarns, polyamide yarns or the like.

The bag body26of this specific embodiment includes a main inflatable portion28for protecting the upper body MU of the occupant MP, a head protecting portion42which is disposed in a vicinity of an upper end28aof the main inflatable portion28, and a pair of thigh arresting portions50L,50R which are disposed in a vicinity of a lower end28bof the main inflatable portion28and each serve as a positioning inflatable portion.

The main inflatable portion28for protecting the upper body MU of the occupant MP is configured to be inflated into a generally triangular prism extending generally in a left and right direction. More particularly, as can be seen inFIGS.5and6, the main inflatable portion28as fully deployed has a generally right triangular shape which has the oblique side in the front, when viewed from a side (i.e. from left or right), and has a generally rectangular shape elongated in an up and down direction when viewed from front or back. The main inflatable portion28includes a front wall29which is configured to be deployed in the front side facing away from the occupant MP, a rear upper wall30and a rear lower wall31which are configured to be deployed towards the occupant MP, and a left wall32and a right wall33which are configured to oppose each other in the left and right direction at airbag deployment. The left wall32and right wall33are each provided with a vent hole36for releasing an extra inflation gas. The rear upper wall30constitutes an upper-body arresting surface39which is configured to be deployed in front of the occupant MP for arresting the upper body MU of the occupant MP. As can be seen inFIG.11, the rear upper wall30(or upper-body arresting surface39) is configured to extend generally along an up and down direction in proximity to the upper body MU of the occupant MP at airbag deployment. The rear lower wall31is configured to extend generally along a front and back direction, along the thighs MT of the occupant MP at airbag deployment. The main inflatable portion28is provided with at least one communication hole35which provides gas communication between the main inflatable portion28and the conduit portion52, in a vicinity of the center in the left and right direction of and at a rear end31aof the rear lower wall31, so as to receive an inflation gas from the conduit portion52, as can be seen inFIGS.6and8. More specifically, two communication holes35are arranged side by side along the left and right direction in a vicinity of the center in the left and right direction of the main inflatable portion28, as can be seen inFIG.8. In the main inflatable portion28of this embodiment, a region of the rear lower wall31located farther forward than the conduit portion52at airbag deployment constitutes a thigh contact surface38which contacts with upper surfaces of the thighs MT of the occupant MP at airbag deployment. In this specific embodiment, a width in the up and down direction and a width in the left and right direction of the main inflatable portion28as fully inflated are set such that the rear upper wall30(or upper-body arresting surface39) is able to cover generally an entirety of the upper body MU of the occupant MP except the head MH. A width in the front and back direction of the main inflatable portion28as fully inflated is set such that the rear lower wall31(or the thigh contact surface38) is able to cover the upper surfaces of the thighs MT to a vicinity of knees.

The head protecting portion42includes a front inflatable portion43which is deployable in front of the head MH and a pair of side inflatable portions44L,44R which extend rearward from opposite ends in the left and right direction of the front inflatable portion43. As can be seen inFIG.6, the front inflatable portion43is continuous with and extends upward from the upper end28aof the main inflatable portion28. A width in the left and right direction of the front inflatable portion43is generally identical to the width in the left and right direction of the main inflatable portion28, as can be seen inFIG.5. The side inflatable portions44L,44R of this specific embodiment extend obliquely rearward from the left and right ends of the front inflatable portion43such that the leading ends44cdraw farther away from each other, as can be seen inFIG.7. The side inflatable portions44L and44R are generally bilaterally symmetrical in shape as fully inflated. The head protecting portion42is in gas communication with the main inflatable portion28by the lower end of the front inflatable portion43, thus configured to receive an inflation gas via the main inflatable portion28. In this specific embodiment, the head protecting portion42is formed into a generally board shape having a generally uniform thickness from the front inflatable portion43to the side inflatable portions44L,44R. This board shape and inclination of the side inflatable portions44L,44R with respect to the front inflatable portion43are formed by a pair of regulating tethers47L,47R located inside of the head protecting portion42. More specifically, the front inflatable portion43includes a front wall43aand a rear wall43bwhile each of the side inflatable portions44L,44R includes a front wall44aand a rear wall44b, each of which are opposed to each other in the front and back direction. As can be seen inFIG.7, each of the regulating tethers47L,47R connects a center in the left and right direction of the front wall43aof the front inflatable portion43and a border between the rear wall43bof the front inflatable portion43and the rear wall44bof the side inflatable portion44L/44R. In this specific embodiment, the regulating tethers47L,47R are bilaterally symmetrical in shape, and each formed of a band-shaped body whose width in an up and down direction is slightly smaller than that of the head protecting portion42, as can be seen inFIGS.5and6. A length of each of the regulating tethers47L,47R is set so as to make the side inflatable portions44L,44R steadily inclined with respect to the front inflatable portion43.

To describe more specifically, the head protecting portion42(i.e. the front inflatable portion43and side inflatable portions44L,44R) has such a width in the up and down direction as to be able to cover generally an entirety of the head MH of the occupant MP in the up and down direction. An inclination angle θ (FIG.7) of the side inflatable portions44L,44R with respect to the front inflatable portion43is approximately 40°, in this specific embodiment. A width in the left and right direction of each of the side inflatable portions44L,44R is set so as to cover a front half region of the head MH of the occupant MP sitting in the seat1, as viewed from side of the airbag25as deployed, as can be seen inFIGS.7and11. As described above, the width in the left and right direction of the front inflatable portion43is generally identical to that of the main inflatable portion28, which is sufficient for covering generally an entirety of the upper body MU of the occupant MP. In other words, the front inflatable portion43of this specific embodiment is greater in width in the left and right direction than the head MH. Further, the side inflatable portions44L and44R extend from the left and right ends of the front inflatable portion43in such a manner as to draw away from each other. That is, the head protecting portion42is configured to cover the front and sides of the head MH of the occupant MP while leaving a void space between itself and the head MH. The head protecting portion42is provided for cushioning and protecting the head MH of the occupant MP moving forward or diagonally forward in the event that an impact is applied to the seat1from forward or diagonally forward. A thickness of the head protecting portion42as fully inflated is such as to restrain the moving head MH of the occupant MP steadily.

The thigh arresting portions50L,50R as the positioning inflatable portions protrude downwardly from left and right ends of the lower end28bregion of the main inflatable portion28. In this specific embodiment, the thigh arresting portions50L,50R are identical in outer shape, and located at bilaterally symmetrical positions with respect to the center in the left and right direction of the main inflatable portion28. As viewed from side, each of the thigh arresting portions50L,50R is located generally at the center in the front and back direction of the main inflatable portion28, as can be seen inFIG.6. As can be seen inFIGS.5and9, the thigh arresting portions50L,50R protrude outwardly in the left and right direction while extend downwardly from the lower end28bregion of the main inflatable portion28. The thigh arresting portions50L,50R are each in communication with the main inflatable portion28by the upper end50cregions, thus configured to receive an inflation gas via the main inflatable portion28. Each of the thigh arresting portions50L,50R includes an inner wall50aand an outer wall50bwhich are opposed to each other in an inboard-outboard direction. To describe more specifically, each of the thigh arresting portions50L,50R has such a profile at airbag deployment that the width in an up and down direction is greater than the width in a front and back direction and that narrows towards the leading end (i.e. lower end50d), as can be seen inFIG.6. Each of the thigh arresting portions50L,50R as fully inflated has an outer shape that narrows towards the leading end (i.e. lower end50d) when viewed from the front or back, too, as can be seen inFIGS.5and9. The inner walls50aof the thigh arresting portions50L,50R, which are opposed to each other at airbag deployment, extend obliquely so as to draw apart from each other towards the leading ends (i.e. lower ends50d), when viewed from the front or back. Referring toFIG.9, a distance between the root regions (or upper end50cregions) of the thigh arresting portions50L,50R at airbag deployment is set to be slightly greater than a width of thighs MT of an average-sized adult occupant (which corresponds to AM50 dummy). A width in the up and down direction of each of the thigh arresting portions50L,50R is so set as to cover sides of the thighs MT generally entirely.

In the exemplary embodiment, the inner walls50aof the thigh arresting portions50L,50R constitute contact surfaces that contact with and is supported by side surfaces of the thighs MT (which serves as an environmental member disposed in a circumference of the lap belt10as restraining the pelvic region MW of the occupant MP) at airbag deployment. Since the inner walls50aof the thigh arresting portions50L,50R, i.e. the contact surfaces, are located bilaterally symmetrically with respect to the center in the left and right direction of the main inflatable portion28, when the main inflatable portion28is deployed in such a manner that its center in the left and right direction is dislocated from the center in the left and right direction of the upper body MU of the occupant MP, one of the contact surfaces (i.e. the inner walls50aof the thigh arresting portions50L,50R) will butt a side of the thigh MT, so that the airbag25will move towards the opposite direction by a reaction force and the position of the main inflatable portion28will be corrected such that the center in the left and right direction of the main inflatable portion28as deployed and the center in the left and right direction of the upper body MU of the occupant MP are generally aligned. The thigh arresting portions50L,50R are also designed to restrain the thighs MT of the occupant MP from moving outwardly in the left and right direction when an impact is applied to the seat1from forward or diagonally forward. To this end, a thickness of each of the thigh arresting portions50L,50R as fully inflated is so set as to restrain the moving thighs MT of the occupant MP steadily.

The conduit portion52is coupled to the bag body26at the leading end52b, which is closed, and connected to the pipe19at the root region52a. As can be seen inFIG.12, the conduit portion52is designed to extend along a left and right direction, generally along the lap belt10at airbag deployment. Referring toFIGS.5,6, and8, the conduit portion52is joined to an underside of the main inflatable portion28of the bag body26as deployed by the leading end52bregion, where the afore-described communication holes35provide gas communication between the conduit portion52and main inflatable portion28. A length of the conduit portion52at airbag deployment is set so that a center in the left and right direction of its region joined to the main inflatable portion28(the region provided with the communication holes35) is generally aligned with the center in the left and right direction of the upper body of an averaged-sized adult occupant (which corresponds to AM50 dummy) sitting in the seat1.

The mounting portion55which attaches the bag body26to the lap belt10is located on an underside of the leading end52bregion of the conduit portion52, in this specific embodiment. The mounting portion55is formed into a tube so that the lap belt10goes there through, and is arranged generally along the left and right direction, i.e. generally along the lap belt10, as can be seen inFIGS.5,6and8. The mounting portion55is so arranged that its center in the left and right direction is generally aligned with the center in the left and right direction of the main inflatable portion28as fully inflated. With the configuration that the lap belt10is passed through the mounting portion55, the airbag25(or bag body26) is coupled to the lap belt10in such a manner as to be movable relative the lap belt10in the left and right direction (i.e. in a length direction of the lap belt10) to a certain degree.

When the inflator17of the occupant protection system S in accordance with the exemplary embodiment as mounted on a vehicle is actuated, an inflation gas emitted from the inflator17will flow into the bag body26via the conduit portion52, so that the bag body26will break the cover22and protrudes forward and upwardly from the lap belt10, and be deployed as can be seen inFIG.3(with dashed-and-double-dotted lines) andFIGS.10to12.

In the occupant protection system S in accordance with the exemplary embodiment, each of the thigh arresting portions (i.e. the positioning inflatable portions)50L,50R includes the contact surface (i.e. the inner wall50a) that contacts and is supported by the thigh MT of the occupant MP (i.e. the environmental member or object which is disposed in a circumference of the lap belt10as restraining the pelvic region MW of the occupant MP at airbag deployment) at airbag deployment. The occupant protection system S is able to position the airbag25at airbag deployment such that the center in the left and right direction of the main inflatable portion28is generally aligned with the center in the left and right direction of the upper body MU of the occupant MP by making the contact surface (i.e. the inner wall50a) of the thigh arresting portion (i.e. the positioning inflatable portion)50L,50R butt the environmental member. To describe more specifically, when the airbag25protrudes from the storage in the lap belt10(the region enclosed by the cover22), the airbag25may be deployed in such a manner that the center in the left and right direction of the main inflatable portion28is slightly dislocated to the left or right from the center in the left and right direction of the upper body MU of the occupant MP. At this time, since the airbag25is coupled to the lap belt10in a movable fashion with respect to the lap belt10by the mounting portion55, if one of the inner walls50aof the thigh arresting portions50L,50R butts a side surface of the thigh MT, the airbag25will be moved back from the dislocating direction by a reaction force, so that the center in the left and right direction of the main inflatable portion28will be generally aligned with the center in the left and right direction of the upper body MU of the occupant MP. With this simple configuration, the position of the main inflatable portion28of the airbag25is controlled steadily at deployment and the main inflatable portion28restrains the upper body MU of the occupant MP adequately. In the occupant protection system S in accordance with the exemplary embodiment, especially, the airbag25is stored in the storage in the lap belt10of the three-point seat belt (in the void space formed between the lap belt10and the cover22) in the folded form57. Although the position of the storage (i.e. position of the airbag25) in the seatbelt as worn by the occupant MP can vary with respect to the occupant MP due to difference in physical size of the occupant MP, the position of the main inflatable portion28of the airbag25with respect to the upper body MU of the occupant MP will be controlled steadily by the thigh arresting portions (i.e. the positioning inflatable portions)50L,50R formed in the airbag25at airbag deployment even if the airbag25is stored in a position dislocated from the center in the left and right direction of the occupant MP. Thus, the position of the main inflatable portion28of the airbag25will be controlled steadily such that the center in the left and right direction of the main inflatable portion28is generally aligned with that of the occupant MP, and the main inflatable portion28will protect the upper body MU of the occupant MP adequately.

Therefore, the occupant protection system S in accordance with the exemplary embodiment is able to protect the upper body MU of the occupant MP adequately with the airbag25stored in the lap belt10despite its simple configuration.

In the occupant protection system S in accordance with the exemplary embodiment, the main inflatable portion28of the airbag25is configured to be inflated into a generally triangular prism extending generally along the left and right direction so as to be deployed over the front of the upper body MU of the occupant MP with the thigh contact surface38contacting with upper surfaces of the thighs MT. With this configuration, at airbag deployment, the thigh contact surface38of the main inflatable portion28will be supported by the thighs MT by a wide area, and the upper-body arresting surface39which is configured to face the occupant MP will arrest the upper body MU of the occupant MP, so that a bending of the occupant MP, i.e. a behavior of the occupant MP that the upper body MU moves towards the lower body MD, will also be prevented, as can be seen inFIG.14. In the occupant protection system S in accordance with the exemplary embodiment, the airbag25further includes the head protecting portion42as well as the thigh arresting portions50L,50R for arresting the thighs MT from the left and right. By thus arresting the thighs MT with the thigh arresting portions50L,50R and restraining the occupant MP from moving towards the left or right, the airbag25will protect an entirety of the upper body MU including the head MH steadily.

In the occupant protection system S in accordance with the exemplary embodiment, the two thigh arresting portions (i.e. the positioning inflatable portions)50L,50R protrude from both ends in the left and right direction of the lower end28bregion of the main inflatable portion28at airbag deployment, and the inner walls50a(i.e. the surfaces of the positioning inflatable portions50L,50R that are opposed to each other at airbag deployment) constitute the contact surfaces. With this configuration, when, by way of example, the thigh arresting portion50R (either one of the thigh arresting portions50L,50R) butts a side of the thigh MTR and the airbag25(or bag body26) is restrained from moving towards the left, as can be seen in (A) ofFIG.13, the airbag25may move back towards the right too much due to a reaction force. However, since the other thigh arresting portion50L then butts a side of the thigh MTL as can be seen in (B) ofFIG.13, the airbag25will be prevented from moving back too much, so that the airbag25will be deployed such that its center in the left and right direction is generally aligned with the center in the left and right direction of the upper body MU of the occupant MP quickly, as can be seen in (C) ofFIG.13, and protect the upper body MU of the occupant MP quickly with the main inflatable portion28. If such an advantageous effect does not have to be considered, it is also conceivable to locate the positioning inflatable portion64,64A only in either left or eight of the main inflatable portion62, as in later-described airbags60,60A depicted inFIGS.15and16. Even with such airbags60,60A that includes the positioning inflatable portion only in either left or right, it is basically unlikely that the airbag60/60A will move in one direction unduly due to reaction force because a conduit portion67/67A for feeding the bag body61/61A with an inflation gas is connected with the inflator17.

In the occupant protection system S in accordance with the exemplary embodiment, moreover, the thigh arresting portions (i.e. the positioning inflatable portions)50L,50R are each configured to protrude downwardly from the main inflatable portion28, and the inner walls (i.e. the contact surfaces)50aof the thigh arresting portions50L,50R extend obliquely in such a manner as to draw apart from each other towards the leading ends (i.e. the lower ends50d), when viewed from the front or back. The inner walls50athus configured help deploy the thigh arresting portions50L,50R on the left and right sides of the thighs MT smoothly at airbag deployment. If such an advantageous effect does not have to be considered, the thigh arresting portions may be configured like those in a later-described airbag75depicted inFIGS.17and18. In the airbag75, each of thigh arresting portions79L,79R has a generally uniform width (or thickness) in a front and back direction from the root region to the leading end, and inner walls (i.e. contact surfaces) of the thigh arresting portions79L,79R which are opposed to each other at airbag deployment extend generally along an up and down direction.

An airbag60in accordance with an alternative embodiment is now described with reference toFIG.15. The airbag60includes a bag body61, a conduit portion67which is connected with the inflator17for feeding the bag body61with an inflation gas, and a mounting portion70which attaches the bag body61to the lap belt10. The bag body61includes a main inflatable portion62for protecting the upper body MU of the occupant MP, and a positioning inflatable portion64located in a vicinity of the lower end62aof the main inflatable portion62. In a similar fashion to the mounting portion55of the airbag25in the foregoing embodiment, the mounting portion70is formed into a tube so that the lap belt10goes there through, and coupled to an underside of the main inflatable portion62. The main inflatable portion62is configured to be inflated into a generally triangular prism extending generally in a left and right direction. Although not depicted in detail in the drawings, in a similar fashion to the main inflatable portion28of the airbag25in the foregoing embodiment, the main inflatable portion62as fully deployed has a generally right triangular shape which has the oblique side in the front, when viewed from a side (i.e. from the left or right), and has a generally rectangular shape elongated in an up and down direction when viewed from the front or back, as can be seen inFIG.15. The positioning inflatable portion64partially protrudes from a right end (an outboard side in the vehicle width direction) of the lower end62aregion of the main inflatable portion62. The positioning inflatable portion64is in gas communication with the main inflatable portion62by the root end (i.e. the left end in an inflated state).

This airbag60is configured such that a leading end surface of the positioning inflatable portion64serves as a contact surface64a, and butts a door trim DT that serves as an outboard-side vehicle member which is located in an outer side in the vehicle width direction (i.e. on the right side) of the seat1of the vehicle, when the main inflatable portion62is deployed in such a manner that its center in the left and right direction is dislocated to an outward direction in the vehicle width direction (i.e. towards the right, inFIG.15) with respect to the center in the left and right direction of the upper body MU of the occupant MP. Here, the door trim DT constitutes the environmental member that is disposed in a circumference of the lap belt10at airbag deployment. When the main inflatable portion62is deployed such that its center in the left and right direction is generally aligned with the center in the left and right direction of the upper body MU of the occupant MP, the contact surface64aof the positioning inflatable portion64will not contact with the door trim DT, as can be seen inFIG.15.

In this airbag60, the conduit portion67constitutes an initial inflow portion that delivers an inflation gas emitted from the inflator17towards the positioning inflatable portion64. More specifically, although the conduit portion67is connected with the pipe19of the inflator17in a similar fashion to the conduit portion52of the airbag25, a leading end67aregion of the conduit portion67is inserted into the bag body61(or main inflatable portion62). The leading end67aregion is provided with an opening68from which the inflation gas is released. The leading end67aof the conduit portion67is located proximate to the positioning inflatable portion64so that the inflation gas is discharged towards the positioning inflatable portion64from the opening68.

This airbag60will also be subjected to position control at airbag deployment such that the center in the left and right direction of the main inflatable portion62is generally aligned with the center in the left and right direction of the upper body MU of the occupant MP by making the contact surface (i.e. the right surface)64aof the positioning inflatable portion64butt the door trim DT (i.e. the outboard-side vehicle member which serves as the environmental member which is disposed in a circumference of the lap belt10as restraining the pelvic region MW of the occupant MP). More specifically, the airbag60may be deployed in such a manner that the center in the left and right direction of the main inflatable portion62is slightly dislocated to an outboard direction (in other words, to the right or towards the door trim DT) with respect to the center in the left and right direction of the upper body MU of the occupant MP. At this time, since the airbag60is coupled to the lap belt10in a movable fashion with respect to the lap belt10by the mounting portion70, if the contact surface64adisposed at the leading end (or right end) of the positioning inflatable portion64butts the door trim DT, the airbag60will be moved back to the left by a reaction force such that the center in the left and right direction of the main inflatable portion62is generally aligned with the center in the left and right direction of the upper body MU of the occupant MP. With this simple configuration, the position of the main inflatable portion62of the airbag will be controlled steadily at deployment and the main inflatable portion62will restrain the upper body MU of the occupant MP adequately.

In the airbag60, the conduit portion67serves as the initial inflow portion that delivers an inflation gas emitted from the inflator17towards the positioning inflatable portion64to inflate the positioning inflatable portion64earlier than the main inflatable portion62. This configuration will inflate the positioning inflatable portion64immediately and make the same butt the door trim DT in an initial stage of airbag deployment, thus performing position correction of the main inflatable portion62with respect to the upper body MU of the occupant MP quickly.

Further alternatively, the airbag may be configured like an airbag60A depicted inFIG.16. The airbag60A has such a configuration that the airbag60is left-right reversed except the conduit portion67A. A positioning inflatable portion64A partially protrudes from a left end (an inboard side in the vehicle width direction) of a lower end62aregion of the main inflatable portion62A. A conduit portion67A constitutes an initial inflow portion that delivers an inflation gas emitted from the inflator17towards this positioning inflatable portion64A. The conduit portion67A is closed at the leading end67a, and includes an outlet port68A for releasing an inflation gas towards the positioning inflatable portion64A in the intermediate region. The airbag60A is designed such that a leading end surface (or left side surface), i.e. a contact surface64a, of the positioning inflatable portion64A butts a center console C as an inboard-side vehicle member which is located in an inner side in a vehicle width direction (i.e. on the left side) of the seat1, when the main inflatable portion62A is deployed in such a manner that its center in the left and right direction is dislocated to an inward direction in the vehicle width direction (i.e. towards the left) with respect to the center in the left and right direction of the upper body MU of the occupant MP. Here, the center console C constitutes the environmental member which is disposed in a circumference of the lap belt10at airbag deployment.

Further alternatively, the airbag may be configured like an airbag75depicted inFIGS.17and18. The airbag75includes a bag body76, a conduit portion52B which is connected with the inflator17for feeding the bag body76with an inflation gas, and a mounting portion55B which attaches the bag body76to the lap belt10. The bag body76includes a main inflatable portion62B for protecting the upper body MU of the occupant MP, and a positioning inflatable portion78located in a vicinity of a lower end62aof the main inflatable portion62B. The conduit portion52B and the mounting portion55B each have the same configurations as those of the conduit portion52and mounting portion55in the airbag25in the foregoing embodiment. The main inflatable portion62B has a similar configuration to that of the airbag60in the foregoing embodiment except in communicating with the positioning inflatable portion78via a not-shown communication hole disposed in the front lower end region as deployed. The positioning inflatable portion78is located proximate to a front end of the main inflatable portion62B as deployed, and includes a pair of thigh arresting portions79L,79R which are configured to be deployed on the left and right sides of the thighs MT, and a connecting portion80which is configured to extend generally along a left and right direction and connects upper end regions of the thigh arresting portions79L and79R at airbag deployment. The positioning inflatable portion78is in gas communication with the main inflatable portion62B by a region of the connecting portion80. The thigh arresting portions79L,79R are configured to cover left and right sides of the thighs MT. Similarly to the thigh arresting portions50L,50R of the airbag25in the foregoing embodiment, inner walls of the thigh arresting portions79L,79R, which are located in an inner side in the vehicle width direction, serve as contact surfaces79awhich are to butt the thighs MT. In the airbag75, each of the thigh arresting portions79L,79R has a uniform width (or thickness) in a front and back direction from the root region to the leading end, and the inner walls (i.e. contact surfaces79a) of the thigh arresting portions79L,79R which are opposed to each other at airbag deployment extend generally along an up and down direction. The connecting portion80connecting the thigh arresting portions79L,79R is configured to be inflated generally into a rod shape extending generally along the left and right direction in an underside of the main inflatable portion62B.

This airbag75will also be subjected to position control at airbag deployment such that the center in the left and right direction of the main inflatable portion62B is generally aligned with the center in the left and right direction of the upper body MU of the occupant MP by making the contact surfaces79aof the positioning inflatable portion78(i.e. the thigh arresting portions79L,79R) butt side surfaces of the thighs MT which serve as an environmental member which is disposed in a circumference of the lap belt10as restraining the pelvic region MW of the occupant MP. More specifically, the airbag75may be deployed in such a manner that the center in the left and right direction of the main inflatable portion62B is slightly dislocated to the left or right with respect to the center in the left and right direction of the upper body MU of the occupant MP. At this time, since the airbag75is coupled to the lap belt10in a movable fashion with respect to the lap belt10by the mounting portion55B, if the contact surfaces79abutt the thighs MT, the airbag75will be moved back by a reaction force such that the center in the left and right direction of the main inflatable portion62B is generally aligned with the center in the left and right direction of the upper body MU of the occupant MP. With this simple configuration, the position of the main inflatable portion62B of the airbag75will be controlled steadily at deployment and the main inflatable portion62B will restrain the upper body MU of the occupant MP adequately.

In the airbag75, the positioning inflatable portion78includes the connecting portion80that connects the thigh arresting portions79L,79R and is configured to be inflated into a rod shape in a vicinity of the front end of and in the underside of the main inflatable portion62B. With this configuration, the connecting portion80will lift the front end region of the main inflatable portion62B so that an upper-body arresting surface82of the main inflatable portion62B, which is designed to be deployed in a vicinity of the upper body MU of the occupant MP, will be deployed at a slant such that the upper end region draws close to the occupant MP, at airbag deployment.

When the positioning inflatable portions are configured to protrude from both the left and right ends of the main inflatable portion, the contact surfaces of the positioning inflatable portions may also be configured to butt and be supported by not only thighs of the occupant but also a seat main body of the seat1, a lower end region of the seatback of the seat1, or the like. That is, the environmental member referred to in this specification may be composed of these members.

In the occupant protection system S of the exemplary embodiments, the seatbelt7and inflator17are mounted on the seat1. When using the airbag25or75which performs position control using the thighs MT of the occupant MP as the environmental member, with this configuration, the occupant protection system S will be able to protect the occupant MP sitting in the seat1adequately even if the seat1is moved largely with respect to the vehicle, like, by being slid forward or backward, or turned. If such an advantageous effect does not have to be considered, the seatbelt may be configured such that the retractor is mounted on the vehicle body like a normal seatbelt for a vehicle, or the inflator may be mounted on the vehicle body.

The exemplary embodiments of the present disclosure relates to an occupant protection system for protecting an occupant sitting in a seat of a vehicle, the occupant protection system including: a three-point seatbelt that includes a lap belt which is configured to arrest a pelvic region of the occupant; an inflator; and an airbag that is formed of a sheet material having flexibility and stored in a storage in the lap belt in a folded form. The airbag is coupled to the lap belt in such a manner as to be movable relative to the lap belt in a left and right direction, and configured to be inflated and deployed upward from the storage when fed with an inflation gas from the inflator. The airbag includes: a main inflatable portion that is configured to be deployed in front of an upper body of the occupant for protecting the upper body; and a positioning inflatable portion that protrudes at least from a first end in a left and right direction of a lower end region of the main inflatable portion, the positioning inflatable portion including a contact surface that contacts and is supported by an environmental member which is disposed in a circumference of the lap belt at airbag deployment, the positioning inflatable portion helping align a center in the left and right direction of the main inflatable portion generally with a center in a left and right direction of the upper body by making the contact surface butt the environmental member at airbag deployment.

The occupant protection system in accordance with the exemplary embodiment is able to position the airbag at airbag deployment such that the center in the left and right direction of the main inflatable portion is generally aligned with the center in the left and right direction of the upper body of the occupant by making the contact surface of the positioning inflatable portion butt the environmental member which is disposed in a circumference of the lap belt as restraining the pelvic region of the occupant. To describe more specifically, when the airbag protrudes from the storage in the lap belt, the airbag may be deployed in such a manner that the center in the left and right direction of the main inflatable portion is slightly dislocated to the left or right from the center in the left and right direction of the upper body of the occupant. At this time, since the airbag is coupled to the lap belt in a movable fashion with respect to the lap belt, if the contact surface of the positioning inflatable portion butts the environmental member, the airbag will be moved back from the dislocating direction by a reaction force, so that the center in the left and right direction of the main inflatable portion will be generally aligned with the center in the left and right direction of the upper body of the occupant. With this simple configuration, the airbag is able to position the main inflatable portion at deployment steadily and restrain the upper body of the occupant adequately. In the occupant protection system in accordance with the exemplary embodiment, especially, the airbag is stored in the storage in the lap belt of the three-point seat belt in the folded form. Although the position of this storage in the seatbelt as worn by the occupant can vary with respect to the occupant due to difference in physical size of the occupant, the position of the main inflatable portion of the airbag with respect to the upper body of the occupant will be controlled steadily by the positioning inflatable portion formed in the airbag at airbag deployment even if the airbag is stored in a position dislocated from the center in the left and right direction of the occupant. Thus, the position of the main inflatable portion of the airbag will be controlled steadily such that the center in the left and right direction of the main inflatable portion is generally aligned with that of the occupant, and the main inflatable portion will protect the upper body of the occupant adequately.

Therefore, the occupant protection system in accordance with the exemplary embodiment is able to protect the upper body of the occupant adequately with the airbag stored in the lap belt despite its simple configuration.

The environmental member which the contact surface of the positioning inflatable portion is to butt at airbag deployment will be an outboard-side vehicle member which is located in an outer side in a vehicle width direction of the seat, or an inboard-side vehicle member which is located in an inner side in the vehicle width direction of the seat.

In the occupant protection system in accordance with the exemplary embodiment, the airbag may further include an initial inflow portion that delivers an inflation gas emitted from the inflator towards the positioning inflatable portion to inflate the positioning inflatable portion earlier than the main inflatable portion. This configuration will inflate the positioning inflatable portion immediately in an initial stage of airbag deployment so that the positioning inflatable portion butts the environmental member quickly, so that the position control of the main inflatable portion with respect to the upper body of the occupant will be performed quickly.

In the occupant protection system in accordance with the exemplary embodiment, the positioning inflatable portions may be configured to protrude from both ends in the left and right direction of the lower end region of the main inflatable portion at airbag deployment such that surfaces of the two positioning inflatable portions that are opposed to each other at airbag deployment constitute the contact surfaces. With this configuration, when, by way of example, the airbag which has been restrained from moving towards the left or right by either one of the positioning inflatable portions is about to move back to an opposite direction too much due to a reaction force, the other positioning inflatable portion will prevent such a travel of the airbag, so that the airbag will be deployed such that its center in the left and right direction will be generally aligned with the center in the left and right direction of the upper body of the occupant quickly, and protect the upper body of the occupant quickly with the main inflatable portion.

When the occupant protection system is configured like this, the environmental member may be composed of thighs of the occupant. In this case, the positioning inflatable portions may be configured to protrude downwardly from the main inflatable portion so that the contact surfaces may each contact with sides of the thighs at airbag deployment. Further, the contact surfaces may be configured to extend obliquely so as to draw apart from each other towards the leading ends, when viewed from front or back. The contact surfaces thus configured will help deploy the positioning inflatable portions on the left and right sides of the thighs smoothly at airbag deployment.