Abstract:
A safety belt for a vehicle which can be worn in a manner of wearing suspenders to prevent a concentration of pressure to a part of the body of a seat occupant, and to uniformly distribute impact to thereby safely protect the seat occupant even upon the occurrence of an emergency during travel. To accomplish the above-described object, the safety belt for a vehicle according to the present invention comprises a pair of belts spaced apart from each other in a vertical direction on the front surface of a seatback and a connection unit for interconnecting the pair of belts.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to safety belts for vehicles and, more particularly, to a safety belt for a vehicle which is configured in such a way that a user wears the seat belt in a manner similar to that of suspenders so that pressure is prevented from being concentrated on a portion of the body of the user, and impact is evenly dispersed to the body of the user, thus safely protecting the user even if an unexpected accident occurs when the vehicle is in motion. 
         [0003]    2. Description of the Related Art 
         [0004]    Generally, in traffic accidents, such as vehicle collision or rollover accidents, people in vehicles are mainly injured by the following reasons: a person in a vehicle which has been in motion is thrown out of the vehicle under the influence of inertia and is shocked by colliding with the road; a driver collides with the windshield, dashboard, etc., resulting in serious head or neck damage; or the chest of the driver is damaged by colliding with the steering wheel. 
         [0005]    Although safety belts for vehicles cannot fundamentally prevent traffic accidents, they hold users, who are sitting on seats, to prevent the users from being thrown out of the vehicles or colliding with parts in the passenger compartments when traffic accidents occur. Therefore, safety belts mitigate the fatality rate or the extent of injuries in traffic accidents. Further, laws have been established to make it mandatory to wear safety belts. 
         [0006]    Safety belts for vehicles must be able to reliably protect users in case of an emergency. Particularly, in the case of the driver&#39;s seat, the safety belts must not make it inconvenient for drivers to drive vehicles. 
         [0007]    As shown in  FIG. 1 , such a safety belt for a vehicle typically includes a belt  10  which supports the body of a user, a retractor  12  around which the belt  10  is wound, a tongue plate  14  which is coupled to the belt  10 , a buckle  16  to which the tongue plate  14  coupled to the belt  10  is fastened to hold the belt  10 , and an anchor  18  which is used as a shaft for supporting the belt  10 . The belt  10  comprises a shoulder belt part  10   a  and a waist belt part  10   b.    
         [0008]    As such, it is obvious that the safety belts for vehicles are very effective at reducing human injury or fatalities in accidents. 
         [0009]    In other words, wearing a safety belt markedly reduces the extent of injury compared to when it is not worn. However, despite wearing the safety belt, the neck, stomach, chest, waist, etc., of a user may be injured. 
         [0010]    In detail, the safety belt includes the shoulder belt part, and the waist belt part. In a collision, the shoulder belt part supports the upper body of the user, and the waist belt part supports the pelvic region. However, because the position at which the waist belt part is disposed on the body of the user is unstable, for example, if the user sits in such a way that his/her back is bent when the vehicle is in motion, in the majority of cases, the waist belt part is disposed on the lower abdomen rather than being maintained in the initial position. In this case, a collision may cause problems, such as enterorrhexis, fracturing of the spine, etc. 
         [0011]    Furthermore, in a collision, the belt is prevented from being unwound, but the upper body of the user is biased forwards by inertial force. Due to this, as the length of the shoulder belt part extends, the waist belt part is tightened, thus causing enterorrhexis, fracture of spine, etc. 
         [0012]    In addition, under normal conditions, the safety belt compresses portions of the body of the user, making the user uncomfortable. Thus, some drivers may use a clip to loosen the belt when driving a vehicle. This is very dangerous, for example, increasing the extent of injury, when a collision occurs. 
         [0013]    Moreover, if the safety belt that the user is wearing loosens, when an airbag deploys in a collision, the airbag may intensively strike the upper body of the user. 
         [0014]    In this case, a large impact is applied to the user by the pressure of the airbag just as the airbag strikes the user. This may cause the user to be injured by, for example, a neck fracture. 
         [0015]    Further, if the user inclines the seat back rearwards to take a comfortable position, the safety belt cannot reliably support the user because it is spaced apart from the body of the user. In a collision, the body of the user is tossed forwards, thus increasing the extent of injury. 
         [0016]    Meanwhile, the conventional safety belt is designed for an adult. Therefore, in the case of an infant or child, a separate infant safety belt is required. Expenses for purchasing the separate infant safety belt increase the financial burden. Furthermore, a lot of time is required to install the infant safety belt. 
       SUMMARY OF THE INVENTION 
       [0017]    Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a safety belt for a vehicle in which belts are configured in a shape similar to that of suspenders so that the belts support the shoulders of a user, for example, a driver, who is sitting on a seat, thus preventing pressure from being concentrated on portion of the body of the driver when the vehicle is in motion, thereby making it possible for the driver to drive the vehicle in a comfortable position. 
         [0018]    Another object of the present invention is to provide a safety belt for a vehicle in which because the belts support the shoulders of the driver, the impact of a vehicle collision can be evenly dispersed across the entire upper body of the driver, thus more effectively preventing the driver from being injured. 
         [0019]    A further object of the present invention is to provide a safety belt for a vehicle in which each of a buckle and a tongue plate has an insert slot to which the corresponding belt is coupled, and a twist prevention slot which prevents the belt from being twisted, and the belt is double-coupled to the insert slot and the twist prevention slot, thus more reliably preventing the belt from being twisted. 
         [0020]    Yet another object of the present invention is to provide a safety belt for a vehicle in which retractors are received in a rear surface of a seat back, and the upper end of each retractor is rotatably supported by a hinge, so that even when the driver adjusts the angle at which the seat back is inclined depending on the body type of the driver, the retractors can consistently stay in the vertical state, thus preventing the retractors from malfunctioning. 
         [0021]    Still another object of the present invention is to provide a safety belt for a vehicle in which the retractors that are received in the rear surface of the seat back are covered with a cover plate, thus facilitating repair or maintenance of the retractors. 
         [0022]    Still another object of the present invention is to provide a safety belt for a vehicle in which each retractor is provided with a control unit so that when the vehicle which is in motion reaches a preset speed, the belt is automatically restricted from being unwound from the retractor, thus stably supporting the driver on the seat back and protecting the driver from safety accidents which may be caused while the vehicle is in motion. 
         [0023]    Still another object of the present invention is to provide a safety belt for a vehicle in which belt guide members are provided on the upper end of the seat back to guide the corresponding belts such that the belts pass over the same portions of both sides of the body of the driver, thereby preventing the driver from suffering from enterorrhexis, fracture of spine, etc. in a vehicle collision. 
         [0024]    Still another object of the present invention is to provide a safety belt for a vehicle in which a release pin is provided in the buckle to allow the driver to forcibly unfasten the safety belt, so that even if the safety belt cannot be unfastened when a vehicle collision occurs, the driver can use the release pin to forcibly unfasten the safety belt and safely escape from the vehicle which has been in an accident. 
         [0025]    In order to accomplish the above object, in an aspect, the present invention provides a safety belt for a vehicle, including: a pair of belts disposed on a front surface of a seat back in a vertical direction at positions spaced apart from each other; and a fastening unit for fastening the pair of belts to each other. 
         [0026]    In another aspect, the present invention provides a safety belt for a vehicle, including: a pair of retractors provided in a rear surface of a seat back; a pair of belts extracting from the respective retractors and extending on a front surface of the seat back in a vertical direction; and a fastening unit for fastening the pair of belts to each other. 
         [0027]    Preferably, an installation depression may be formed in the rear surface of the seat back, and a hinge shaft may be provided in the installation depression, wherein the retractors are disposed in the installation depression and are rotatably coupled to the hinge shaft. 
         [0028]    Furthermore, stoppers may be provided on the hinge shaft on opposite sides of each of the retractors. 
         [0029]    In addition, guide depressions may be formed in the seat back. The guide depressions may extend from the installation depression in a vertical direction. 
         [0030]    The safety belt may further include a cover plate covering the rear surface of the seat back. 
         [0031]    The safety belt may further include belt guide members respectively provided at both sides on an upper end of the seat back, the belt guide members guiding the corresponding belts. 
         [0032]    Each of the belt guide members may include: a casing fastened to the upper end of the seat back, with holes respectively formed in front and rear ends of the casing; and a guide shaft provided in the casing. 
         [0033]    Each of the retractors may include: a body to which a drum is coupled, the drum having ratchet teeth, wherein the corresponding belt is wound around the drum; a ball disposed in the body at a predetermined position below the ratchet teeth, with a control shaft coupled to the ball; a ball housing onto which the ball is seated, the ball housing having a hole into which a lower end of the control shaft is inserted; and an operating lever having a pawl at a predetermined position thereof, the pawl being locked to or removed from the ratchet teeth when the ball is moved by vertical movement of the control shaft. 
         [0034]    The retractor may further include a control unit controlling unwinding of the belt. 
         [0035]    The control unit may include: a motor provided in a side of the body of the retractor in which the ratchet teeth are formed; and a rotary member reversibly rotated by the motor, with a contact protrusion provided on a circumferential outer surface of the rotary member, the contact protrusion coming into contact with or moving away from the control shaft. 
         [0036]    The safety belt may further include a control box operating the motor. 
         [0037]    The safety belt may further include a switch provided on the control box so that when the switch is operated, the pawl of the operating lever which has been locked to the ratchet teeth is removed from the ratchet teeth for a predetermined time. 
         [0038]    The safety belt may further include anchors coupled to ends of the respective belts, the anchors being fixed to opposite sidewalls of a lower end of the seat back so that the belts are disposed on opposite sides of the front surface of the seat back. 
         [0039]    The fastening unit may include: a tongue plate provided on either of the pair of belts; and a buckle provided on a remaining one of the pair of belts at a position corresponding to the tongue plate so that the tongue plate is removably fastened to the buckle. 
         [0040]    The tongue plate may include a hook locked to or unlocked from the buckle. The tongue plate may have: a first insert slot into which the corresponding belt is inserted, the first insert slot being disposed at a side opposite to the hook; and a first twist prevention slot into which the belt is inserted, the first twist prevention slot being disposed at a position adjacent to the first insert slot and at a slant with respect to the first insert slot to prevent the belt from being twisted. 
         [0041]    The buckle may include a connection member disposed on a first end of the buckle opposite to a second end thereof to which the tongue plate is fastened. The connection member may have: a second insert slot into which the corresponding belt is inserted; and a second twist prevention slot into which the belt is inserted, the second twist prevention slot being disposed at a position adjacent to the second insert slot and at a slant with respect to the second insert slot to prevent the belt from being twisted. 
         [0042]    Furthermore, an open recess may be formed in the first end of the buckle in such a way that the first end of the buckle is open, wherein seating depressions corresponding to each other may be formed in respective inner sidewalls of the open recess, and a through hole may be formed in each of the seating depressions. A cover member may be provided on the buckle to cover the seating depression, the cover member being hinged at a first end thereof to the buckle, with a coupling hole formed in a second end of the cover member. A release pin may be inserted into the through holes of the open recess via the coupling hole of the cover member. 
         [0043]    The connection member may include an insert part inserted into the open recess of the buckle, the insert part having seating protrusions seated into the respective seating depressions. 
         [0044]    The release pin may have a handle on a first end thereof, with a locking ball provided in a second end of the release pin. 
         [0045]    Each of the tongue plate and the connection member may have an arc shape that is concave with respect to a body of a user, and the buckle may have an arc shape that is convex to correspond to the arc shape of the connection member. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0046]    The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0047]      FIG. 1  is a view showing a conventional safety belt for a vehicle; 
           [0048]      FIG. 2  is a perspective view illustrating a safety belt for a vehicle, according to an embodiment of the present invention; 
           [0049]      FIG. 3  is a front view illustrating the safety belt according to the present invention; 
           [0050]      FIG. 4A  is an exploded perspective view showing the installation of retractors according to the present invention; 
           [0051]      FIG. 4B  is a sectional view showing the installation of the retractor according to the present invention; 
           [0052]      FIGS. 5A and 5B  are views showing a control unit installed in the retractor according to the present invention; 
           [0053]      FIGS. 6A and 6B  are views showing a belt guide member according to the present invention; 
           [0054]      FIG. 7  is an exploded perspective view illustrating a fastening unit according to the present invention; 
           [0055]      FIG. 8  is a plan view illustrating the fastening unit according to the present invention; 
           [0056]      FIG. 9  is a view showing a user who is wearing the safety belt to illustrate the operation of the safety belt according to the present invention; 
           [0057]      FIG. 10  is a view showing the safety belt which is not in use, illustrating the operation of the safety belt according to the present invention; and 
           [0058]      FIG. 11  is a view showing the operation of the safety belt according to the present invention, illustrating the buckle being forcibly unlocked. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0059]    Hereinafter, a safety belt for a vehicle according to the present invention will be described in detail with reference to the attached drawings. 
         [0060]      FIG. 2  is a perspective view illustrating the safety belt for a vehicle, according to an embodiment of the present invention. 
         [0061]      FIG. 3  is a front view illustrating the safety belt according to the present invention.  FIG. 4A  is an exploded perspective view showing the installation of retractors according to the present invention.  FIG. 4B  is a sectional view showing the installation of the retractor according to the present invention.  FIGS. 5A and 5B  are views showing a control unit installed in the retractor according to the present invention.  FIGS. 6A and 6B  are views showing a belt guide member according to the present invention.  FIG. 7  is an exploded perspective view illustrating a fastening unit according to the present invention.  FIG. 8  is a plan view illustrating the fastening unit according to the present invention. 
         [0062]    As shown in  FIGS. 2 through 8 , the safety belt  100  according to the present invention includes a pair of retractors  110  which are installed in a rear surface of a seat back  102 . 
         [0063]    Each retractor  110  has the same structure as that of a typical retractor which is used for vehicle safety belts. The structure of the retractor  110  will be briefly explained below. The retractor  110  includes a body  112  to which a drum  114  is coupled. The drum  114  has ratchet teeth  114   a  on a predetermined portion thereof. A belt  210 ,  210   a  is wound around the drum  114 . A ball  116  is disposed in the body  112  at a predetermined position below the ratchet teeth  114   a.  A control shaft  116   a  is coupled in the vertical direction to the ball  116  in such a way that upper and lower ends of the control shaft  116   a  protrude upwards and downwards from the ball  116 . 
         [0064]    The retractor  110  further includes a ball housing  118  into which the lower end of the control shaft  116   a  is inserted, and onto which the ball  116  is seated. The refractor  110  further includes an operating lever  119  which has a pawl  119   a  at a predetermined position thereof. The pawl  1119   a  is locked to or removed from the ratchet teeth  114   a  when the ball  116  is moved by vertical movement of the control shaft  116   a.    
         [0065]    To install the retractors  110  each of which has the above-mentioned structure in the seat back  102 , an installation depression  104  is formed in the rear surface of the seat back  102  to a predetermined depth. The two retractors  110  are installed in the installation depression  104  at positions spaced apart from each other by a predetermined distance. 
         [0066]    In detail, a hinge shaft  106  is provided at an upper position in the installation depression  104 . The retractors  110  are rotatably coupled to the hinge shaft  106 . In an embodiment, a mounting bracket  120  is provided on an upper end of the body  112  of each retractor  110  and has a mounting hole  122  into which the hinge shaft  106  is inserted. Thus, the retractor  110  is rotatably coupled to the hinge shaft  106  in such a way that the hinge shaft  106  is inserted into the mounting hole  122  of the mounting bracket  120 . 
         [0067]    Furthermore, stoppers  108  are fastened to the hinge shaft  106  on opposite sides of the mounting bracket  102  to prevent the retractor  110  from undesirably moving along the hinge shaft  106  to the left or the right. 
         [0068]    In the present invention, although the angle at which the seat back  102  is inclined is changed, the retractor  110  can be maintained in a vertical state because it is rotatable around the hinge shaft  106 . Further, a control unit  130  is provided in the body  112  of each retractor  110  to control unwinding of the belt  210 ,  210   a.    
         [0069]    The control unit  130  includes a motor  132  which is fastened to the body  112  of the retractor  110  at a position corresponding to the direction in which the ratchet teeth  114   a  are formed. 
         [0070]    A rotary member  134  is provided on a motor shaft of the motor  132  and is rotated by the operation of the motor  132 . The rotary member  134  is disposed under the ball housing  118  and has thereon a contact protrusion  136  which comes into contact with the lower end of the control shaft  116   a  that protrudes downwards from the ball housing  118 , so that the control shaft  116   a  is vertically moved by the contact protrusion  136 . 
         [0071]    In the present invention, a control box  140  is provided to operate the motor  132  of the control unit  130 . 
         [0072]    In detail, a predetermined speed is set by a user and stored in the control box  140 . When the vehicle reaches the preset speed, the motor  132  is automatically operated so that the contact protrusion  136  of the rotary member  134  moves the control shaft  116   a  upwards. Then, the pawl  119   a  of the operating lever  119  is disposed at an upper position to be locked to the ratchet teeth  114   a,  thus preventing the belt  210 ,  210   a  from being unwound from the retractor  110 . 
         [0073]    On the contrary, when the speed of the vehicle becomes lower than the preset speed, the control box  140  senses this and automatically operates the motor  132  so that the contact protrusion  136  of the rotary member  134  moves away from the control shaft  116   a.  Then, the control shaft  116   a  moves downwards to a lower position, thus allowing for the user to extract the belt  210 ,  210   a  from the retractor  110 . 
         [0074]    As such, when the speed of the vehicle reaches the preset speed, the control unit  130  receives this information from the control box  140  to operate the motor  132 . Then, the rotary member  134  is rotated by the operation of the motor  132 . Due to the rotation of the rotary member  134 , the contact protrusion  136  pushes the control shaft  116   a  upwards. The control shaft  116   a  that moves upwards pushes the pawl  119   a  of the operating lever  119  upwards so that the pawl  119   a  engages with the ratchet teeth  114   a , thus preventing the belt  210 ,  210   a  from being unwound. 
         [0075]    Meanwhile, a switch  142  is provided on the control box  140  to allow the locking of the control unit  130  to be released by the demand of the user, who is wearing the safety belt  100 , even when the speed of the vehicle exceeds the preset speed and the pawl  119   a  of the operating lever  119  has been locked to the ratchet teeth  114   a.    
         [0076]    Therefore, even when the pawl  119   a  of the operating lever  119  has been locked to the ratchet teeth  114   a  under the control of the control unit  130 , as necessary, the pawl  119   a  of the operating lever  119  is released from the ratchet teeth  114   a  for a predetermined time. After the predetermined time has passed, the motor  132  is operated by the control of the control box  140  so that the pawl  119   a  of the operating lever  119  is locked to the ratchet teeth  114   a  again. 
         [0077]    Furthermore, two guide depressions  109  are formed in the rear surface of the seat back  102  and extend from the installation depression  104  upwards. The guide depressions  109  function to guide the corresponding belts  210  and  210   a  extracted from the retractors  110 . 
         [0078]    The rear surface of the seat back  102  is covered with a cover plate  107 . That is, the cover plate  107  is fastened to the seat back  102  by bolts or the like to cover the installation depression  104  and the guide depressions  109 . 
         [0079]    Meanwhile, the belts  210  and  210   a  are extracted from the two retractors  110 , pass over the upper end of the seat back  102 , and are disposed on opposite sides of a front surface of the seat back  102 . Ends of the belts  210  and  210   a  are respectively fastened to anchors  212  which are fixed to opposite sidewalls of a lower end of the seat back  102 . 
         [0080]    In other words, the belts  210  and  210   a  are extracted from the retractors  110  and are disposed on opposite sides of the front surface on the seat back  102  in the shape of suspenders. 
         [0081]    Therefore, the belts  210  and  210   a  that are disposed on the opposite sides of the front surface of the seat back  102  support the shoulders of the user in a manner similar to wearing suspenders, thus preventing the belts  210  and  210   a  from compressing the chest and abdomen of the user. Therefore, the user can not only sit on the seat in a comfortable position but can also comfortably drive the vehicle. 
         [0082]    In this embodiment, belt guide members  220  which guide the corresponding belts  210  and  210   a  are provided on the upper end of the seat back  102  at both sides corresponding to the respective guide depressions  109 . 
         [0083]    Each belt guide member  220  includes a casing  222  which is fastened to a predetermined portion of the upper end of the seat back  102  by a fastening means and has a hole  224  therein. A guide shaft  226  which guides the belt  210 ,  210   a  is provided in the hole  224  of the casing  222 . 
         [0084]    Due to the belt guide members  220 , the belts  210  and  210   a  which are extracted from the retractor  110  can always move based on the constant positions on the seat back. 
         [0085]    Furthermore, a fastening unit  310  is provided on the belts  210  and  210   a  and fastens the belts  210  and  210   a  to each other to support a user who is sitting on the seat. 
         [0086]    The fastening unit  310  includes a tongue plate  320  which is provided on one (for example,  210 ) of the belts  210  and  210   a,  and a buckle  330  which is provided on the other belt ( 210   a ). The tongue plate  320  is removably fastened into the buckle  330 . One end of the tongue plate  320  has a hook  322  which is removably locked to the buckle  330 . A first insert slot  324  into which the belt  210  is inserted is formed in the tongue plate  320  at a side opposite to the hook  322 . A first twist prevention slot  326  into which the belt  210  is also inserted is formed in the tongue plate  320  at a position adjacent to the first insert slot  324  and is slanted at an angle with respect to the first insert slot  324  to prevent the belt  210  from being twisted. 
         [0087]    The belt  210  is successively inserted into the first insert slot  324  and the first twist prevention slot  326 . Thus, the user can easily adjust the position at which the tongue plate  320  is disposed. In addition, when the belt  210  is not in use, the tongue plate  320  can be maintained in a state of being in close contact with the seat back  102 . 
         [0088]    The buckle  330  has in a first end thereof a fastening hole  332  into which the hook  322  of the tongue plate  320  is inserted. 
         [0089]    A connection member  350  to which the belt  210   a  is coupled is provided on a second end of the buckle  330  that is opposite the fastening hole  332 . 
         [0090]    The buckle  330  includes a button  334  which is used to unlock the tongue plate  320  from the buckle  330 . An open recess  336  is formed in the second end of the buckle  330  that is opposite to the button  334 . Seating depressions  336   a  corresponding to each other are formed in respective inner sidewalls of the open recess  336 . A through hole  336   b  is formed in each seating depression  336   a  in the lateral direction of the buckle  310 . 
         [0091]    A cover member  338  which covers seating depressions  336   a  is provided on the buckle  330  in such a way that a first end of the cover member  338  is rotatably coupled to the buckle  330  by a hinge  338   a.  A coupling hole  338   b  is formed in a lower portion of a second end of the cover member  338 . 
         [0092]    Further, a release pin  340  is inserted into the through holes  336   b  of the open recess  336  via the through hole  336   b  of the cover member  338 . 
         [0093]    In detail, a handle  342  is provided on a first end of the release pin  340  that protrudes outwards from the buckle  330 . A locking ball  344  which prevents the release pin  340  from being undesirably removed from the buckle  330  is provided in a second end of the release pin  340  that protrudes outwards from the buckle  330  in the direction opposite to the direction in which the handle  342  protrudes outwards. 
         [0094]    In detail, an installation hole  344   a  is formed through the second end of the release pin  340  in the lateral direction of the release pin  340 . The locking ball  344  is inserted into the installation hole  344   a.  An elastic member  344   b  which elastically supports the locking ball  344  is provided in the installation hole  344   a.  A bolt  344   c  is threaded into the installation hole  344   a  to hold the elastic member  344   b  in the installation hole  344   a.    
         [0095]    Furthermore, the connection member  350  is inserted into the open recess  336  of the buckle  330 . In an embodiment, an insert part  352  is provided on the corresponding end of the connection member  350 . Seating protrusions  352   a  protrude outwards from the insert part  352  in opposite directions. The seating protrusions  352   a  are movably inserted into the corresponding seating depressions  336   a  so that the connection member  350  is movably coupled to the buckle  330 . 
         [0096]    Here, the seating protrusions  352   a  of the insert part  352  are inserted into the corresponding seating depressions  336   a  of the buckle  330  in such a way that the insert part  352  is disposed below the release pin  340 . 
         [0097]    Furthermore, a second insert slot  354  into which the belt  210   a  is inserted is formed in the connection member  350  at a side opposite the insert part  352 . A second twist prevention slot  356  is formed in the connection member  350  at a position adjacent to the second insert slot  354  and slants with respect to the second insert slot  354  to prevent the belt  210   a  from being twisted. 
         [0098]    A method of coupling the belt  210   a  to the connection member  350  is the same as the method of coupling the belt  210  to the tongue plate  320  through the first insert slot  324  and the first twist prevention slot  326 . 
         [0099]    In addition, the buckle  330  is movably coupled to the connection member  350 . Therefore, when the belts  210  and  210   a  are not in use, the buckle  330  is rotated around the junction between the buckle  330  and the connection member  350  and is folded onto the connection member  350  to be brought into contact with the connection member  350 . Thus, the buckle  330  can be stably maintained in a state of being in close contact with the seat back  102 . 
         [0100]    Meanwhile, when the user who is wearing the safety belt  100  is involved in a vehicle collision, the fastening unit  310  of the safety belt  100  may not be unlocked. At this time, the user holds the handle  342  of the release pin  340  and strongly pulls it. Then, the release pin  340  is removed from the buckle  330  so that the cover member  338  can be open. Thereby, the connection member  350  coupled to the belt  210   a  can be easily removed from the buckle  330 , thus allowing the user to move away from the accident vehicle. 
         [0101]    Preferably, each of the tongue plate  320  and the connection member  350  has an arc shape that is concave on its surface which comes into contact with the body of the user. 
         [0102]    As such, the tongue plate  320  and the connection member  350  have arc shapes corresponding to the body of the user that are designed to make contact with the body of the user. The buckle  330  has a shape corresponding to the arc shape of the connection member  350 , that is, a convex surface corresponding to the arc shape of the connection member  350  is formed on the buckle  330  so that after the buckle  330  is folded onto the connection member  350  to make contact with it, the buckle  330  is reliably maintained in a state of close contact with the connection member  350 . 
         [0103]    Therefore, when the user wears the safety belt  100 , the tongue plate  320  and the connection member  350  that have arc shapes can reliably come into close contact with the body of the user. In the case where the safety belt  100  is not in use, after the buckle  330  and the connection member  350  are folded around the junction therebetween, the buckle  330  can be reliably maintained in a state of close contact with the connection member  350 . 
         [0104]    The operation of the safety belt according to the present invention having the above-mentioned construction will be described with reference to an example of the case of a driver&#39;s seat. 
         [0105]      FIG. 9  is a view showing the user who is wearing the safety belt to illustrate the operation of the safety belt according to the present invention.  FIG. 10  is a view showing the safety belt which is not in use, illustrating the operation of the safety belt according to the present invention.  FIG. 11  is a view showing the operation of the safety belt according to the present invention, illustrating the buckle being forcibly unlocked. 
         [0106]    As shown in the drawings, in the safety belt  100  according to the present invention, a driver sits on the seat and puts the belts  210  and  210   a  on his/her shoulders. Subsequently, the driver fastens the tongue plate  320  of the fastening unit  310  to the buckle  330 , thus completing the wearing of the safety belt  100 . 
         [0107]    In the present invention, the belts  210  and  210   a  support the shoulders of the driver in a manner similar to wearing suspenders, thus allowing the driver to freely move. Further, the belts  210  and  210   a  do not compress the chest or abdomen of the driver, thus making it possible for the driver to drive the vehicle in a comfortable position. 
         [0108]    If the vehicle is involved in a collision after the driver has fastened the safety belt  100 , the belts  210  and  210   a  supports the shoulders of the driver so that an impact caused by the collision is dispersed over the entire body of the driver rather than being concentrated on one spot, thus preventing the driver from suffering from enterorrhexis, fracture of spine, etc. 
         [0109]    Meanwhile, when the angle at which the seat back  102  is inclined is adjusted, for example, when the seat back  102  is inclined backwards, each retractor  110  rotates around the hinge shaft  106  due to its on weight such that the retractor  110  is always in the vertical state. Thereby, the belt  210 ,  210   a  can be reliably extracted from or retracted into the retractor  110 . 
         [0110]    Furthermore, when the speed of the vehicle which is in motion reaches the preset speed, the motor  132  of the control unit  130  is operated to rotate the rotary member  134 . Because of the rotation of the rotary member  134 , the contact protrusion  136  pushes the control shaft  116   a  upwards. When the control shaft  116   a  that is pushed by the contact protrusion  136  upwards reaches the uppermost position, the motor  132  stops. 
         [0111]    As such, when the contact protrusion  136  of the rotary member  134  pushes the control shaft  116   a  upwards, the control shaft  116   a  moves the pawl  119   a  of the operating lever  119  to engage the pawl  119   a  with the ratchet teeth  114   a  of the drum  114  so that the belt  210 ,  210   a  can no longer be extracted from the retractor  110 . Thereby, the driver can be maintained in a state of being held by the belts  210  and  210   a  and so be in close contact with the seat back  102 . 
         [0112]    Meanwhile, in the present invention, the first and second twist prevention slots  326  and  236  are respectively formed in the tongue plate  320  and the connection member  350  of the buckle  330 . Therefore, when the safety belt  100  is not in use or the belts  210  and  210   a  are fastened to each other so that the safety belt  100  can be worn, the belts  210  and  210   a  are prevented from being twisted. 
         [0113]    Furthermore, the belt  210  is coupled to the tongue plate  320  by the first insert slot  324  and the first twist prevention slot  326 . Thus, when the safety belt  100  is not in use, the tongue plate  320  can maintain a state of close contact with the seat back  102 . 
         [0114]    Also, the belt  210   a  is coupled to the connection member  250  of the buckle  330  in the same manner as the method of coupling the belt  210  to the first insert slot  324  and the first twist prevention slot  326  of the tongue plate  320 . Thus, the belt  210   a  is prevented from being twisted. When the safety belt  100  is not in use, the buckle  330  rotates around the connection junction between the buckle  330  and the connection member  350 . Thereby, the buckle  330  is brought into close contact with the upper portion of the connection member  350  so that the buckle  330  can be reliably maintained in a state of being in close contact with the seat back  102 . 
         [0115]    Meanwhile, when the vehicle which is in motion is involved in a collision, the tongue plate  320  and the buckle  330  of the safety belt  100  may be damaged and thus not be separated from each other. At this time, the user who is wearing the safety belt  100  holds the handle  342  of the release pin  340  which has been locked to the buckle  330  and strongly pulls it. Then, the release pin  340  is removed from the buckle  330  so that the cover member  338  can open. Thereafter, the connection member  350  is separated from the buckle  330 , thus allowing the user to be easily released from the safety belt  100 . 
         [0116]    As a result, the user can easily unfasten the safety belt  100  to safely escape from the vehicle which has been in an accident. 
         [0117]    As described above, in a safety belt for a vehicle according to the present invention, belts which are configured in a shape similar to that of suspenders support the shoulders of a user, for example, a driver, who is sitting on a seat. Thus, when the vehicle is in motion, pressure is prevented from being concentrated on portion of the body of the driver. Therefore, the present invention makes it possible for the driver to drive the vehicle in a comfortable position. 
         [0118]    Furthermore, because the belts support the shoulders of the driver, impact caused by a vehicle collision can be evenly dispersed to the entire upper body of the driver, thus more effectively preventing the driver from being injured. 
         [0119]    In addition, each of a buckle and a tongue plate has an insert slot to which the corresponding belt is coupled, and a twist prevention slot which prevents the belt from being twisted. Because the belt is double-coupled to the insert slot and the twist prevention slot, the belt can be reliably prevented from being twisted. 
         [0120]    Further, retractors are received in a rear surface of a seat back. The upper end of each retractor is rotatably supported by a hinge. Thus, even when the driver adjusts the angle at which the seat back is inclined depending on the body type of the driver, the retractors can always be maintained in the vertical state, thus preventing the retractors from malfunctioning. 
         [0121]    Moreover, the retractors that are received in the rear surface of the seat back are covered with a cover plate. Hence, repair or maintenance of the retractors can be facilitated. 
         [0122]    Also, each retractor is provided with a control unit so that when the speed of the vehicle which is in motion reaches a preset degree, the belt is automatically restricted from being unwound from the retractor. Thus, the present invention can stably support the driver on the seat back and protect the driver from safety accidents which may occur while the vehicle is in motion. 
         [0123]    Furthermore, belt guide members which guide the corresponding belts are provided on the upper end of the seat back. Thus, the belts are guided by the belt guide members so that the belts pass over the same portions of both sides of the body of the driver. Therefore, when a vehicle collision occurs, the present invention prevents the driver from suffering from enterorrhexis, fracture of spine, etc. 
         [0124]    In addition, a release pin is provided in the buckle to allow the driver to forcibly unfasten the safety belt. Thus, even if the safety belt cannot be unfastened when a vehicle collision occurs, the driver can use the release pin to forcibly unfasten the safety belt and safely escape from the vehicle which has been in an accident. 
         [0125]    Although the preferred embodiment of the safety belt for vehicles according to the present invention has been disclosed for illustrative purposes, the present invention is not limited to this embodiment and can be applied to typical retractors or buckles which are installed in vehicles. Furthermore, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.