Abstract:
Disclosed is a structure for installing an air bag module on a steering wheel, capable of improving operation performance of the air bag module by maximizing space utilization of an interior of the steering wheel, and by minimizing interference between parts. A structure for installing an air bag module on a steering wheel includes: a main body consisting of a rim constituting an outer ring, a core constituting a center portion, a spoke connecting the rim with the core; an inflator mounted on the rim, one end of which is connected with a connector, and to the other end of which a nozzle for discharging a gas, is provided; an air bag for expanding, provided with the gas from the inflator; a cushion housing for receiving the air bag and is fixed to an upper plane of the core; and a pipe tube for sealing surroundings of the nozzle, and connecting the inflator with the housing.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an air bag module for a vehicle, and more particularly to a structure for installing an air bag module on a steering wheel for a vehicle capable of maximizing space utilization of an interior of the steering wheel, improving operation performance of the air bag module by minimizing interference between parts constituting the air bag module. 
     2. Description of the Related Art 
     Generally, an air bag apparatus, which is an apparatus for protecting a passenger upon collision of a vehicle, protects safety of a driver and a passenger, working together with a seat belt. 
     Such air bag apparatus works in the following manner, in which: when a sensor and an ECU (Electronic Controlling Unit) detect impulse, an inflator is operated instantly. Then a compressed gas is discharged and the air bag is expanded, so that impulse with respect to a face and a chest of a driver, is possibly relieved. 
     Among such air bag apparatus, particularly a driver air bag is generally mounted on a central part of the steering wheel, so that a danger that a face or a chest of a driver is knocked against the steering wheel due to inertia going forward upon collision of a vehicle, may be prevented. 
     An U.S. Pat. No. 6,142,510 (Nov. 7, 2000) discloses in detail a structure of steering wheel on which a driver air bag is mounted. The structure thereof will be described in detail in the following. 
     FIG. 1 a  is a plan view of a structure for a steering wheel of the related art, and FIG. 1 b  is a cross-sectional view of a structure taken along line A—A of FIG. 1 a . Also, FIG. 1 c  is an exploded, perspective view illustrating the whole construction of an air bag module in FIG. 1 a.    
     Referring to FIG. 1 a  through FIG. 1 c , the steering wheel  10  roughly consists of a steering wheel main body  12 , an air bag module  20  mounted within the main body  12 , and an air bag cover  30  for covering the air bag module  20 . 
     Also, the air bag module  20  includes an air bag  21 , a retainer  22 , an inflator  23 , an inflator housing  24 , and a base plate  25 . 
     Here, the air bag  21  is fixed on an upper plane of the base plate  25  with the retainer  22  intervened, and the inflator  23  is fit into a back side of the base plate  25  with the inflator  23  accommodated in the inflator housing  24 . 
     With the inflator  23  and inflator housing  24  fit into the base plate  25  as described above, a nut  27  is fixed to a stud bolt  26  formed on the back side of the retainer  22 , so that assembling of the air bag module  20  is completed. 
     The air bag module  20  assembled through the foregoing procedure, with being fit into the back side of the air bag cover  30 , is joined to a lateral side of the air bag cover  30  corresponding to a lateral side of the retainer  22  by means of a rivet  34  with a bracket  32  intervened. 
     After that, an assembly consisting of the air bag module  20  and the air bag cover  30 , is mounted on a central front side of the main body  12 , so that assembling of the whole steering wheel  10  is completed. 
     In the meantime, FIG. 2 is another embodiment of the related art, schematically showing a structure in which an air bag module is mounted within a steering wheel. 
     As shown in FIG. 2, an air bag module  50  consists of an air bag  52 , an inflator  54  arranged on a lower portion of the air bag  52 , and an inflator housing  56  for receiving the inflator  54 . 
     Also, the steering wheel  40  consists of a rim  42  constituting an outer ring, a core  44  forming a central part, and a spoke  46  connecting the rim  42  with the core  44 . 
     The inflator  54  has a connector  55  for electrically connecting with a controlling unit connected with an impulse detecting sensor within a vehicle, and a horn switch  58  is mounted on an upper portion of the air bag  52 . 
     The air bag module  50  accommodated in an inside of a side wall part  62  of the air bag cover  60 , is joined integrally to the air bag cover  60  by means of a rivet  72  with an inflator housing  56 , the air bag cover  60 , and a bracket  70  faced each other. 
     The air bag cover  60  has a side wall part  62  projected vertically downward a predetermined length from the back side of the air bag cover  60 , for receiving the air bag module  50 , and the air bag cover  60  positioned within the side wall part  62  has, in its back side, a tear line (not shown) of a predetermined shape for exploding upon expansion of the air bag  52 . 
     One end of the bracket  70  is bent outward, for coming in plane contact with a front side of the spoke  46  as shown in FIG. 2, so that this bent portion is fixed to the spoke  46  by means of a bolt  74 . 
     As is revealed in the foregoing construction, the air bag module of the related art is configured such that the air bag cover  60 , the horn switch  58 , the air bag  52 , the inflator  54 , and the connector  55  are sequentially assembled. As the air bag module  50  consisting of combination of a plurality of parts, should be mounted in a limited space within the steering wheel  40 , the size of the air bag module  50  itself is reduced, whereby space for receiving the air bag  52  becomes insufficient and interference with surrounding parts is generated upon unfolding of the air bag  52 . Resultantly, such problems cause deterioration in unfolding performance of the air bag  52 . 
     Also, as space for operation of the horn switch  58  is narrow and interference with other parts is generated, a problem that malfunction of the horn switch  58  is generated, emerges. 
     Additionally, due to interference between the connector  55  connected with a lower end of the inflator  54  and an end terminal of a steering wheel shaft  80  positioned on a lower part of the connector  55 , a short circuit phenomenon of the connector  55  is frequently generated, whereby the air bag  52  is not properly operated. 
     In order to resolve such problems, the inflator  54  within the air bag module  50  should be changed in its specification, and replaced by an inflator of small capacity. But, such measure may cause undesirable results having great effect on operation performance of the air bag module  50 . 
     SUMMARY OF THE INVENTION 
     To solve the above-indicated problems, it is, therefore, an object of the present invention to provide a structure for installing an air bag module on a steering wheel for a vehicle capable of improving rigidity of the steering wheel by making change of a core shape possible while improving unfolding performance of the air bag by suppressing interference between parts within the air bag module and by installing the inflator in an interior of the rim of the steering wheel, achieving integration. 
     The foregoing and other objects and advantages are realized by providing a structure for installing an air bag module on a steering wheel for a vehicle including: a main body consisting of a rim constituting an outer ring, a core constituting a central part, a spoke connecting the rim with the core; an inflator mounted on the rim, one end of which is connected with a connector, and to the other end of which a nozzle for discharging a gas, is provided; an air bag for expanding, provided with the gas from the inflator; a cushion housing for receiving the air bag and is fixed to an upper plane of the core; and a pipe tube for sealing surroundings of the nozzle, and connecting the inflator with the housing; in which the inflator is installed in an interior of the rim. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 a  is a front view of a steering wheel to which an air bag module of the relater art is provided; 
     FIG. 1 b  is a cross-sectional view of a structure, taken along line A—A in FIG. 1 a;    
     FIG. 1 c  is an exploded, perspective view of the whole structure of the air bag module in FIG. 1 a;    
     FIG. 2 is a cross-sectional view schematically illustrating a structure for installing an air bag module in an interior of a steering wheel according to another embodiment of the related art; 
     FIG. 3 is a plan view schematically illustrating a structure for installing an air bag module in an interior of a steering wheel according to an embodiment of the present invention; 
     FIG. 4 is a cross-sectional view schematically illustrating a structure, taken along line B—B in FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A preferred embodiment of the present invention will now be described with reference to the accompanying drawings. 
     FIG. 3 is a plan view schematically illustrating a structure for installing an air bag module in an interior of a steering wheel according to an embodiment of the present invention, and FIG. 4 is a cross-sectional view schematically illustrating a structure, taken along line B—B in FIG.  3 . 
     Referring to FIG.  3  and FIG. 4, a steering wheel main body  100  includes: a rim  110  constituting an outer ring of the main body  100 , a core  120  constituting a central part, a spoke  130  connecting the rim  110  with the core  120 . 
     An air bag module  200  is mounted on an upper part of the main body  100 . The air bag module  200  includes an air bag  210 , an inflator  220  generating a gas, providing the same to the air bag  210 , and a housing  230  receiving the air bag  210 . 
     The inflator  220  is provided to an interior of the rim  110 . At the moment, one single inflator may be provided, but, preferably, a pair of inflators is provided to right and left sides in the interior of the rim  110  so that the inflator is incorporated into the rim. In order for such construction, of course, a space for accommodating the inflator  220  is formed in the interior of the rim  110  though not shown in the drawing. 
     Also, the inflator  220  is electrically connected with a controlling unit (not shown) for receiving a signal from an impulse detecting sensor (not shown) provided to an interior of a vehicle, and the inflators  220  at right and left sides have the same specification (capacity). 
     At the moment, in the present embodiment, the inflators  220  provided to right and left sides of the rim  110  have the same specification, but may have different specification for right and left sides. 
     If the inflators  220  have different specification for right and left sides, absolute amount of working gas flowing into an interior of the air bag  210 , is possibly adjusted and changed, and also it may be configured such that sequential timing signal is applied under the control of the controlling unit so that each inflator  220  is sequentially ignited with a predetermined time interval intervened. Through such construction, step-by-step expansion of the air bag becomes possible and damage inflicted on a passenger is possibly minimized. 
     In the meantime, the inflator  220  has, in its one end, a nozzle  220  so that a gas generated through a combustion process in the inside may be discharged to the outside through the nozzle  222 , and the inflator  220  has, in its other end, a connector  240  for maintaining electrical connection with the controlling unit (not shown) in the outside. 
     At the moment, the nozzle  222  portion of the inflator  220  and the connector  240  portion are preferably arranged on the spoke  130  of the main body  100  so that they are not exposed to the outside. 
     According to the foregoing embodiment, a pair of the inflators  220  is adopted in the interior of the rim  110 , and there is no limitation in a number of inflators  220  installed in the rim  110 . 
     With such construction, if impulse is detected through the impulse detecting sensor (not shown) upon collision of a vehicle, a signal is transferred to the controlling unit, and the controlling unit applies an ignition signal to the inflator  220  through the connector  240  so that a gas generating agent provided to an interior of the inflator  220 , is burned. Also, the generated gas by burning of the gas generating agent is discharged through the nozzle  222 , and expands the air bag  210 . 
     In the meantime, the housing  230  is fixed in an upper plane of the core  120  by means of an appropriate fixing means such as welding or screw joining. At the moment, the back side of the housing  230  is preferably configured such that the shape of the back side corresponds to that of the upper plane of the core  120 , whereby structurally strong fixing state is maintained. 
     Also, a space portion of a predetermined area is formed in an interior of the housing  230 , and the air bag  210  is received through this space portion. At the moment, as the inflator is not provided to the interior of the housing  230  as was in the related art, the space occupied by the inflator is naturally secured, so that the size and shape of the housing  230  could be more freely designed, and at the same time, the size of the air bag  210  could be freely changed and mounted. 
     When degree of freedom for the housing  230  is improved, design change for the core  120  is possibly made with consideration of the shape and the size of the housing  230 . 
     Namely, as the shape of the core  120 , which has been limited due to the size of the air bag module itself, is freely changed to some extent, structural rigidity of the core  120  is increased, so that structural rigidity of the steering wheel main body  100  is increased much more. 
     Additionally, as the core  120  and the housing  230  are freely changed in their shape and design, mutual interference between the core  120  and the housing  230  is possibly suppressed to some extent upon mounting of the air bag module  200 . 
     In the meantime, the pipe tube  250  for accommodating flow of the gas, is provided between the inflator  220  and the housing  230  so that the gas generated from the inflator  220  flows into the interior of the housing  230 . 
     More specifically, one end of the pipe tube  250  is connected to the inflator  220  in the side of the nozzle  222 , for sealing the surroundings of the nozzle, and the other end of the pipe tube  250  is connected to the housing  230 . 
     At the moment, as the nozzle  222  is designed to be arranged on the spoke  130 , it is preferable that the pipe tube  250  naturally runs through the housing  230  along the spoke  130  lest the pipe tube  250  should be exposed to the outside. Also, the connection portion where the inflator  220  and the housing  230  are touched with each other, is joined by means of welding means so that complete sealing is made. 
     In the meantime, as mentioned above, in case that the air bag module  200  is mounted in an interior of the main body  100 , an air bag cover  300  is joined to the main body  100 , for covering the air bag module  200 . 
     At the moment, though not shown, tear line is formed on a central part in the back side of the air bag cover  300  so that the tear line may be exploded to a predetermined shape by expanding force upon expansion of the air bag  210 . 
     Also, a horn switch  260  having a shape where resonance plate is attached to a circular metal plate, for generating a warning sound upon contact of the switch, is mounted on the lower part of the air bag cover  300 , and the lower space ranging from the spoke  130  and the core  120  of the main body, is covered with a back side cover  140 . 
     Operation of the present invention will be described in the following. 
     First of all, upon collision of a vehicle, impulse is detected by the impulse detecting sensor and a signal is transferred to the controlling unit, and the controlling unit transmits an ignition signal to the inflator  220  through the connector  240  in response thereto. 
     When the ignition signal is applied to the inflator  220  through the above procedures, the gas generating agent (not shown) in the inside is exploded and burned, so that a predetermined compressed gas is generated, and the generated compressed gas in this manner is discharged through the nozzle  222 , instantly flowing into the interior of the housing  230  by way of the pipe tube  250 , whereby the air bag  210  is expanded to a predetermined shape. At the moment, the expanding air bag  210  tears off the tear line, getting out of the air bag cover  300 , being unfolded in a predetermined shape, whereby operation of the air bag is completed. 
     According to the present invention described in the foregoing, the following effects are expected. 
     Firstly, the inflator is installed in and incorporated into the interior of the rim in the steering wheel, so that the space for accommodating the inflator is secured in the existing lower portion of the air bag and malfunction due to mutual interference between parts constituting the air bag module, is possibly minimized. 
     Secondly, the connection portion of the pipe tube for enclosing the connection portion of the connector and nozzle in the inflator, is arranged on the spoke of the main body, so that deterioration in appearance and operation performance due to exposure of them to the outside, is prevented in advance. 
     Thirdly, as inner space within the housing is secured, degree of freedom in designing the shape and the size of the housing, is increased, and at the same time, also the size of the air bag could be freely changed and adopted. 
     Fourthly, as the degree of freedom in designing the housing is improved, the shape of the core is also possibly changed, so that the structural rigidity of the steering wheel main body could be remarkably improved thanks to design change of the core. Also, delinquency in mounting of the air bag module caused by interference due to an error in shape between the core and the housing of the related art, could be prevented in advance. 
     Fifthly, the connection portion of the pipe tube facing the inflator and the housing, is joined by means of a welding means, so that a gap generation in the joining portion, is suppressed. Therefore, leakage of the gas generated from the inflator to the outside, could be prevented. 
     Sixthly, thanks to position change of the inflator, the wide space for installing the air bag is secured, and the space for receiving the air bag could be positioned lower, so that malfunction of the horn switch caused due to the narrow installing space of the related art, could be prevented in advance. 
     Seventhly, thanks to position change of the inflator, the whole installing height for the air bag module mounted in the interior of the steering wheel, could be reduced. 
     Eighthly, interference between the connector provided to the lower end of the inflator of the related art and the end terminal of the steering wheel shaft, could be eliminated by the roots, so that such interference does not have any effect whatsoever on deterioration in operation performance of the air bag. 
     Ninthly, a plurality of inflators having a variety of specifications is installed in the interior of the rim in the steering wheel, so that gas output pressure flowing into the inside of the air bag is easily adjusted and changed. Also, it may be configured such that gas generation from the inflator sequentially occurs with a predetermined time interval intervened under an appropriate control for the inflator by the controlling unit, so that step-by-step expansion of the air bag becomes possible and damage inflicted on a passenger could be minimized.