Latching apparatus for inflatable belt device

Information

  • Patent Grant
  • 6591465
  • Patent Number
    6,591,465
  • Date Filed
    Wednesday, February 28, 2001
    24 years ago
  • Date Issued
    Tuesday, July 15, 2003
    21 years ago
Abstract
A latching apparatus for an inflatable belt device which achieves reduction in the gas leakage without losing the smoothness of insertion of a tongue into a buckle, or which achieves reduction in the manufacturing cost and the weight of the latching apparatus. A tongue and a buckle of a latching apparatus for an inflatable belt device have pipes (a tongue pipe, a buckle pipe), through which gas for deploying an inflatable belt flows. The end of the buckle pipe is covered by a buckle cap which is broken when an inflator is actuated. The buckle cap is biased upwardly by a spring fitted around the buckle pipe. A space between the pipes is eliminated by the buckle cap, thereby achieving the reduction in gas leakage. Therefore, the need for excess gas is eliminated, thereby enabling miniaturization of the inflator.
Description




BACKGROUND OF THE INVENTION




The present invention relates to a latching apparatus for an inflatable belt device which achieves reduction of gas leakage without losing the smoothness of insertion of the tongue into the buckle, or reduction in the manufacturing cost and the weight of the latching apparatus. More particularly, the present invention relates to a latching apparatus for an inflatable belt device comprising a tongue and a buckle through which gas generated from an inflator is supplied to a cushion.,




Currently, a seat belt is the most commonly used as a device for restraining an occupant in a vehicle seat in the event of emergency. A typical seat belt device comprises a shoulder webbing to be extended diagonally across the chest from the shoulder to the waist of an occupant, a lap webbing to be extended across the lap in front of the waist of the occupant, the shoulder webbing and the lap webbing being integral as one strip. The proximal end of the shoulder webbing is connected to a seat belt retractor. The retractor prevents the shoulder belt from being withdrawn when an abnormal deceleration is exerted on a vehicle. When locked, the shoulder belt blocks the frontward movement of the occupant.




In recent years, seat belt devices have been refined to further intensify the function of protecting occupants by adding the following techniques:




(1) a pretensioner which rapidly remove slack from the webbing in the event of emergency to achieve initial restraint of the occupant; and




(2) an energy absorbing mechanism (hereinafter, referred to as “EA mechanism”) which allows the webbing to be gradually withdrawn to absorb inertia energy of the occupant when the tension on the webbing exceeds a predetermined value.




However, there remains a need for achieving more soft protection of the occupant by reducing the pressures to the shoulder and the chest of the occupant.




In order to meet this need an inflatable belt device has been developed. The conventional inflatable belt device is a seat belt, of which a portion of a shoulder webbing that touches the shoulder and chest of an occupant's body is composed of an inflatable bag. For example, the bag may be inflated to have a diameter of 14 cm in order to function as an air cushion, thereby softening the pressure exerted on the occupant's body. The bag is shortened in the longitudinal direction when inflated in order to remove the slack from the webbing. In this manner, the inflatable belt also functions as a seat belt pretensioner. Furthermore, the inflatable belt device can also function as an EA mechanism by gradually exhausting gas in the bag at appropriate times. It is expected that inflatable belt devices will increase in popularity due to their improved safety capacity as compared to current seat belt devices.




In general, an inflatable belt device may include a latching apparatus for connecting a seat belt device and a vehicle body. The latching apparatus generally comprises a buckle connected to a vehicle body (e.g. seat frame) and a tongue connected to an end of the inflatable belt. The buckle has a tongue latching mechanism for allowing detachable latching of the tongue.




Inflators for inflating a bag of an inflatable belt device generally include two types. One type is connected to an upper portion of the bag (arranged above the shoulder of the occupant) and the other type is connected to an lower portion of the bag (arranged below the lap of the occupant). In some of the second type of inflators, gas generated by the inflator is supplied into the bag through a buckle. The buckle and a tongue have gas passages, respectively, through which gas generated by the inflator is passed. These passages are designed to communicate with each other when the tongue is inserted to the buckle.




SUMMARY OF THE INVENTION




The inflatable belt mentioned above may be improved in several ways. In order to improve the smoothness of insertion of tongue into the buckle, a suitable clearance should be formed between the tongue and a tongue insertion opening of the buckle in the normal used state of a seat belt. In order to minimize gas leakage, gas generated by the inflator should be supplied into the bag through the passages of the buckle and the tongue without gas leakage when the inflatable belt is deployed (in the event of vehicle collision). Furthermore, easy detachment of the tongue from the buckle should be allowed after the vehicle collision.




An inflatable belt device that satisfies the above points may include a buckle having a gas passage of which one end is positioned inside the buckle so as not to project in the normal used state. The gas passage is arranged to project into the tongue only at the start of vehicle collision and to return to the inside of the buckle by pressure inside the bag during a period between the vehicle collision and the end of the vehicle collision.




In order to cope with a vehicle collision of relatively long period of time (for example, a roll-over that needs to restrain an occupant for several seconds of time), it is required to increase the capacity (molecular amounts of gas) of the inflator to maintain the pressure in the bag. However, the size and the weight of the inflator are increased with increase in the capacity of the inflator, thus also increasing the manufacturing cost. The inflator should be designed to have enough capacity to account for any gas leakage between the buckle and the tongue.




The present invention has been made to solve the aforementioned problems by providing a latching apparatus for an inflatable belt device which achieves reduction in the gas leakage without losing the smoothness of insertion of a tongue into a buckle, and which achieves reduction in the manufacturing cost and the weight of the latching apparatus.




It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed.











BRIEF DESCRIPTION OF THE DRAWINGS




These and other features, aspects and advantages of the present invention will become apparent from the following description, appended claims, and the accompanying exemplary embodiments shown in the drawings, which are briefly described below.





FIG. 1

is a sectional view showing the structure of a latching apparatus for an inflatable belt device of the embodiment, in a state that a tongue is latched to a buckle.





FIG. 2

is an enlarged sectional view of the buckle in a state that the tongue is released.





FIG. 3

is a sectional view showing the connecting relation among an inflatable belt, the tongue, and an upper portion of the buckle of the inflatable belt device.





FIG. 4

is a perspective view showing the appearance of the tongue and the buckle.





FIG. 5

is a front view showing the entire structure of the latching apparatus for the inflatable belt device of the embodiment.





FIG. 6

is a view showing a rear side of the latching apparatus in a state that a cover of the buckle is removed.





FIG. 7

is a schematic perspective view showing the entire structure of the inflatable belt device according to an embodiment of the present invention and also showing its bag deployed state.





FIG. 8

is a perspective view, partially cutaway, showing the structure of this embodiment of the latching apparatus for the inflatable belt device according to the present invention,

FIG. 8

showing a state that a buckle and a tongue are separated away.





FIG. 9

is a front view, partially cutaway, showing the entire structure of the latching apparatus for the inflatable belt device shown in FIG.


8


.




FIGS.


10


(A)-


10


(C) are enlarged sectional views showing the joint portion between a buckle pipe and a tongue pipe in the latched state of the latching apparatus.




FIGS.


11


(A),


11


(B) are enlarged sectional views showing the flow of gas at the joint of the pipes in the latched state of the latching apparatus for the inflatable belt device.





FIG. 12

is a front view showing a variation of the latching apparatus for the inflatable belt device shown in FIG.


8


.




FIGS.


13


(A) through


13


(C) are enlarged views showing a joint portion between a buckle pipe and a tongue pipe of the latching apparatus shown in FIG.


12


.











DETAILED DESCRIPTION




Although references are made below to directions, such as left, right, up, down, etc., in describing the drawings, they are reference relative to the drawings (as normally viewed) for convenience. These directions are not intended to be taken literally or limit the present invention in any form.




In

FIG. 7

, an occupant


11


is shown in a state sitting on a seat


1


. The seat


1


includes a seat squab


5


on which the occupant


11


sits and a seat back


3


. Arranged below the seat squab


5


is a seat frame


7


for supporting the seat


1


and connecting the seat


1


to a vehicle body.




An inflatable belt device


21


comprises the following components: an inflatable belt


31


which is extended diagonally across the chest from the shoulder to the waist of the occupant


11


when the occupant


11


puts on the inflatable belt device


21


; a shoulder webbing


25


which is connected to the upper end of the inflatable belt


31


and is composed of a band-like webbing just like a webbing of a normal seat belt; a deflector


27


for deflecting the shoulder webbing


25


; a retractor


23


for winding up the shoulder webbing


25


and for stopping the shoulder webbing


25


from being withdrawn in the event of emergency; a tongue


33


which is connected to a lower end portion of the inflatable belt


31


to connect the inflatable belt


31


to the vehicle body through a buckle


35


; the buckle


35


which is fixed to the seat frame


7


through an inflator


39


and an anchor bracket


37


; the inflator


39


for generating gas for inflating the inflatable belt


31


; a lap webbing


41


which is extended across the lap of the occupant; a retractor


43


for winding up the lap webbing


41


and for stopping the lap webbing


41


from being withdrawn in the event of emergency; and an acceleration sensor and an electric circuit for actuating the inflator


39


in the event of emergency.




The inflatable belt device


21


is characterized by the structure of the gas passages of the tongue


33


and the buckle


35


. The structure will be described in detail with reference to FIG.


1


through FIG.


6


.




As shown in

FIG. 5

, the latching apparatus


100


of the inflatable belt device


21


comprises the tongue


33


and the buckle


35


. The inflator


39


is connected to a lower portion of the buckle


35


by screws. Disposed on the lower end of the inflator


39


is an anchor bracket


37


.




As shown in

FIG. 4

, the tongue


33


has a tongue plate


33




a


to be inserted into the buckle


35


, a hanger portion


33




c,


and a tongue pipe


33




d.


The tongue plate


33




a


is engaged with a latch


131


of a tongue latching mechanism


110


in the buckle


35


as described later. The hanger portion


33




c


is formed with a slit


33




e


. The lap webbing


41


, described further below, is inserted through the slit


33




e.






The tongue pipe


33




d


is provided at the center in the width direction of the tongue


33


. As shown in

FIG. 3

, connected to the upper end of the tongue pipe


33




d


is a gas inlet


77


(described further below) for the inflatable bag


53


. The tongue pipe


33




d


has a gas passage


33




b


formed inside thereof. As shown in

FIG. 3

, the gas passage


33




b


is formed to communicate with the inside of the bag


53


. As shown in FIG.


1


and

FIG. 3

, a tongue cap


34


made of aluminum is fitted in a lower end opening of the tongue pipe


33




d


. The tongue cap


34


is depressed into the gas passage


33




b


of the tongue pipe


33




d


and is engaged with an edge of the lower end opening of the tongue pipe


33




d


. The tongue cap


34


is designed to give way or rupture when confronted by the gas emitted by the inflator


39


. The tongue cap


34


also functions as a screen gate for preventing dust from invading into the tongue pipe


33




d.






As shown in FIG.


1


and

FIG. 2

, the buckle


35


comprises an outer cover


101


. The cover


101


is formed at its upper portion with an upper opening


35




d


for the insertion of the tongue plate


33




a


. The tongue latching mechanism


110


is provided inside the cover


101


for engaging the tongue plate


33




a


when inserted. The cover


101


is provided at its upper portion with a release button


35




a


. As the button


35




a


is depressed, the tongue latching mechanism


110


is released so as to push out the tongue


33


upwardly.




As shown in

FIG. 6

, the tongue latching mechanism


110


comprises a buckle base


111


made of steel. The buckle base


111


functions as a main rigid member against a force drawing out the inflatable belt


31


. The buckle base


111


is a substantially U-shaped member having a base plate


113


and two side plates


115


. The base plate


113


is formed with two slits


113




a


parallel to each other. Projections


165


of an ejector


161


, further described below, fit and slide into the slits


113




a


. The base plate


113


is formed at its lower portion with a cutout


113




b


into which an external stopper


175


of an inflator connecting member (duct)


171


, described later is fitted. Screws


114


for fixing a buckle pipe


181


and screws


116


for fixing an inflator connecting member are screwed into the base plate


113


.




The latch


131


is held between the side plates


115


of the buckle base


111


. The latch


131


presses down the tongue plate


33




a


when the tongue


33


is latched (see FIG.


1


). As shown in

FIGS. 1

,


2


, and


6


, the latch


131


has a pivot portion


133


and a movable portion


135


. The pivot portion


133


of the latch


131


has lateral protrusions


133




a


. The protrusions


133




a


function as a pivot axis for the latch


131


. The movable portion


135


of the latch


133


is formed with left-side and right-side windows


135




a


as shown in FIG.


6


. The windows


135




a


are closed by a sliding member


141


when the tongue


33


is latched (as shown in

FIG. 1

) and are opened when the tongue


33


is not latched (as shown in FIG.


2


). In the opened state, pawls (not shown) of the side plates


115


enter into the windows


135




a.






The back (a right-side surface in FIG.


1


and

FIG. 2

) of the latch


131


is formed with a tongue engaging projection


137


. The engaging projection


137


is engaged with the tongue plate


33


when the tongue


33


is latched (as shown in FIG.


1


). The latch engaging projection


137


has a tapered portion


137




a


formed on an upper portion thereof. In addition, the latch


131


has a spring hook


138


formed on the upper end thereof. Attached to the spring hook


138


is a spring


104


for connecting and biasing the latch


131


and a sliding member


141


. The latch


131


and the release button


35




a


are connected and biased by a button spring


107


. The connecting state among the ends of the button spring


107


, the latch


131


, and the release button


35




a


is schematically shown. The button spring


107


biases the release button


35




a


in the downward direction and biases the latch


131


to stand upright.




As shown in FIG.


1


and

FIG. 2

, slidably fitted to the left side of the latch


131


(the left side in FIG.


1


and

FIG. 2

) is a sliding member


141


. The sliding member


141


has lateral protrusions


143


. The protrusions


143


close the windows


135




a


(see

FIG. 6

) of the latch


131


when the tongue


33


is latched (in the state shown in

FIG. 1

) and are positioned below the windows


135




a


of the latch


131


so that the windows


135




a


are opened when the tongue


33


is not latched (in the state shown in FIG.


2


). The sliding member


141


has a spring hook


145


formed substantially at its central portion. A spring


104


is disposed between the spring hook


145


and the spring hook


138


of the latch


131


. By this spring


104


, the slider


141


is biased upwardly (toward the position where the windows


135




a


are closed). The sliding member


141


is formed at its upper end with a humulus-like contact portion


147


. The contact portion


147


comes in contact with the inner side of the release button


35




a


when the tongue


33


is latched (as shown in FIG.


1


).




The ejector


161


having a U-like shape in its plan view is held inside the buckle base


111


in such a manner that the ejector


161


can slide along the vertical direction. The ejector


161


is formed to have a dimension larger than the outer diameter of the buckle pipe


181


. The ejector


161


has two projections


165


, as shown in

FIG. 6

, formed on the edge of the opening inside the U-like shape. The projections


165


are slidably fitted in the slits


113




a


of the buckle base


111


. The ejector


161


has an arc-like contact portion


167


formed on the upper end of a surface, opposite to the projections


165


, (the left-side surface in FIG.


1


and

FIG. 2

) of the ejector


161


. The lower end of the tongue plate


33




a


comes in contact with the contact portion


167


when the tongue


33


is latched. The ejector


161


has spring holes (not shown) fitted to the upper ends of springs


108


, described further below.




As shown in FIG.


1


and

FIG. 2

, the buckle pipe


181


is disposed between the base plate


113


and the ejector


161


substantially at the center of the inside of the buckle base


111


. The buckle pipe


181


is fixed to the base plate


113


of the buckle base


111


by screws


114


. The buckle pipe


181


is a gas passage through which gas spouted out from the inflator


39


passes into the inflatable belt


31


.




A buckle cap


103


made of aluminum is put on the upper end of the buckle pipe


181


. The buckle cap


103


is formed with tear lines (not shown). The upper end of the buckle pipe


181


is normally closed by the buckle cap


103


. When the inflatable belt device is actuated, however, the buckle cap


103


is broken along its tear lines by gas pressure generated by the inflator


39


. As shown in

FIG. 1

, there is a clearance (over stroke) C between the inner surface of the buckle cap


103


and the upper end of the buckle pipe


181


, and this clearance absorbs the tolerance among parts and backlash during the insertion of the tongue


33


.




The buckle cap


103


is biased upwardly by the spring


185


fitted around the buckle pipe


181


. Because of the biasing force of the spring


185


, the upper end of the buckle pipe


181


and the lower end of the tongue pipe


33




d


of the tongue


33


are closely in contact with each other when the tongue


33


is latched. The upper end of the inflator


39


is connected to the lower end of the buckle pipe


181


via an O-ring


189


.




To prevent the buckle cap


103


from coming off the buckle pipe


181


, a flange (not shown) of the buckle cap


103


is stopped by pawls (not shown) extending from the buckle base


111


.




This embodiment is designed so that the tongue pipe


33




d


of the tongue


33


and the buckle pipe


181


of the buckle


35


are coaxially aligned and connected to each other substantially at the center in the width direction when the tongue


33


is latched. At this point, in the joint portion between the pipes


33




d


and


181


, the buckle cap


103


is biased toward the tongue cap


34


by the spring


185


so that a space between the pips


33




d


and


181


is eliminated. Since the space is eliminated, gas leakage during the operation of the inflator


39


can be reduced.




As shown in FIG.


1


and

FIG. 2

, a holder


151


is disposed inside the buckle base


111


below the latch


131


and the sliding member


141


. The holder


151


has projections


155


formed on a right side portion thereof (the right side in FIG.


1


and

FIG. 2

) to project upwardly. The springs


108


are fitted around the projections


155


. The upper ends of the springs


108


are fitted to the spring holes (not shown) formed in the bottom of the ejector


161


. The ejector


161


is biased upwardly by the biasing force of the springs


108


so that the ejector


161


is risen when the tongue


33


is not latched, as shown in FIG.


2


.




The holder


151


has two guide poles


153


arranged along the width direction (the depth direction in FIG.


1


and

FIG. 2

) to stand upwardly on a left side portion thereof (the left side in FIG.


1


and FIG.


2


). Guide holes (not shown) of the release button


35




a


slide along the guide poles


153


. Springs


106


are fitted around the guide poles


153


, respectively. The upper ends of the spring


106


are in contact with the bottom of the release button


35




a


. The release button


35




a


is biased upwardly by the biasing force of the springs


106


.




As shown in FIG.


1


and

FIG. 2

, the cylindrical duct


171


is attached to the buckle base


111


below the holder


151


. The duct


171


is formed in its lower inner surface with an internal thread


171




a


(see FIG.


1


and FIG.


2


). Screwed into this internal thread


171




a


is an external thread


39




a


(see FIG.


1


and

FIG. 2

) formed in an upper end portion of the inflator


39


. The duct


171


has the external stopper


175


formed on an end portion thereof as shown in FIG.


6


. The external stopper


175


is formed in a drum-like shape with a neck portion and is fitted to the cutout


113




b


of the base plate


113


of the buckle base


111


. Force of drawing the tongue is transmitted to the duct


171


and the inflator


39


through this joint portion. The duct


171


and the buckle base


111


are fixed to each other by the screws


116


.




As shown in FIG.


1


and

FIG. 2

, the upper end of the inflator


39


is connected to the lower end of the buckle pipe


181


of the buckle


35


via the duct


171


. When the inflator


39


is ignited in the event of vehicle collision, the inflator


39


spouts out gas for deploying the bag toward the gas passage


35




c


of the buckle


35


. The gas is emitted into the hollow portion of the bag through the tongue pipe


33




d


(see

FIG. 3

) of the tongue


33


after passing through the inside of the buckle pipe


181


.




The upper end portion of the inflator


39


is tapered and has the external thread


39




a


formed in the outer surface thereof. The external thread


39




a


is screwed into the internal thread


171




a


of the duct


171


. The inflator


39


includes a propellant and an initiator (not shown) therein. The anchor bracket


37


is provided at the lower end of the inflator


39


as shown in FIG.


5


. The bracket


37


is fixed to the seat frame by bolts or the like. Though the anchor bracket


37


is formed integrally with the body of the inflator


39


in this embodiment, it may be formed separately from the inflator and may be connected by bolts or clamps. It should be noted that the inflator


39


and the bracket


37


may be connected by crimping.




As shown in

FIG. 3

, the inflatable belt


31


is composed of three layer elements. The three layer elements in the order from the inside to the outside are: a bag


53


, a mesh webbing


51


, and a cover


81


. The bag


53


is made by forming (bonding, sewing) for example, nylon plain wave fabric, on which silicone resin is coated, into an envelope shape. The bag


53


is covered by the mesh webbing


51


from the outside. The mesh webbing


51


is formed by knitting, for example, polyester yarns into a cylindrical shape. When the bag


53


is deployed, the mesh webbing


51


expands along the outer surface of the bag


53


. At this point, the mesh webbing


51


shrinks in the longitudinal direction, thereby removing slack from the webbing and imparting pre-tension on the webbing. It should be noted that the bag


53


itself also shrinks in the longitudinal direction during its deployment.




The mesh webbing


51


is covered by the cover


81


from the outside. The cover


81


may be made of polyester plain wave fabric. The cover


81


is torn during the deployment of the bag


53


. The cover


81


is used for accommodating the inflatable belt


31


in a compact form and for making the inflatable belt


31


comfortable to the occupant.




The bag


53


has the gas inlet


77


formed in the lower end thereof. The lower end of the mesh webbing


51


is sewn to the end of the lap webbing


41


by sewing (sewing portion


52


).




The inflatable belt


31


and the tongue


33


are connected to each other by the following method. That is, as shown in

FIG. 3

, the tongue pipe


33




d


of the tongue


33


is inserted into the gas inlet


77


of the bag


53


. The tongue pipe


33




d


and the gas inlet


77


are fastened and fixed by a clamping band


79


. The lap webbing


41


connected to the mesh webbing


51


by sewing is passed through the slit


33




e


of the hanger portion


33




c.






Hereinafter, the actions of the inflatable belt device


21


having the aforementioned construction will be described with reference to FIG.


1


and

FIG. 2

mainly.




When the tongue


33


is not latched to the buckle


35


, as shown in

FIG. 2

, the ejector


161


is pressed upwardly by the biasing force of the springs


108


so that it is in an upward position. At this point, the side of the ejector


161


is in contact with the engaging projection


137


of the latch


131


so that the latch


131


tilts leftward.




To latch the tongue


33


to the buckle


35


, the tongue plate


33




a


of the tongue


33


is inserted into the upper opening


35




d


of the buckle


35


. At this point, the lower edge of the tongue plate


33




a


comes in contact with the contact portion


167


of the ejector


161


. The ejector


161


is depressed against the biasing force of the springs


108


. Then, as shown in

FIG. 1

, the ejector


161


is lowered below the engaging projection


137


of the latch


131


and the tongue plate


33




a


is also lowered below the engaging projection


137


so that the projection


137


enters into a tongue plate hole


33




x


of the tongue plate


33




a


. In this way, the tongue plate


33




a


and the latch


131


are latched. The latch


131


is biased by the button spring


107


so as to stand upright as shown in FIG.


1


. At this point, the sliding member


141


is biased by the compressing force of the spring


104


to move upwardly so as to close the windows


135




a


(

FIG. 6

) of the latch movable portion


135


. This configuration prevents the latch


131


from tilting leftward and prevents the tongue plate


33




a


from coming off.




When the buckle


35


and the tongue


33


are connected to each other, as shown in

FIG. 1

, the tongue pipe


33




d


of the tongue


33


and the buckle pipe


181


of the buckle


35


are aligned coaxially and connected to each other substantially at the center in the width direction. The buckle cap


103


on the upper end of the buckle pipe


181


is biased upwardly by the spring


185


and is thus pressed against the tongue cap


34


of the lower end of the tongue pipe


33




d


. Therefore, the upper end of the buckle pipe


181


and the lower end of the tongue pipe


33




d


are connected closely to each other. It should be noted that the tolerance among parts and backlash during the insertion of the tongue


33


can be absorbed by the clearance C inside the buckle cap


103


.




When gas is emitted out from the inflator


39


, the gas breaks the buckle cap


103


on the upper end of the buckle pipe


181


along the tear lines, further breaks the tongue cap


34


, and is supplied into the bag


53


through the tongue pipe


33




d


. Since there is no space between the upper end of the buckle pipe


181


and the lower end of the tongue pipe


33




d


, i.e. these are closely connected, it achieves the reduction in gas leakage during the actuation of the inflator


39


.




Hereinafter, another embodiment of the latching apparatus for the inflatable belt device according to the present invention will be described with reference to FIG.


8


through

FIG. 13. A

feature of the latching apparatus


200


of this embodiment that differs from the latching apparatus


100


of the aforementioned embodiment is that the gas passages of the tongue and the buckle are arranged on a side not the center.




In the respective drawings, the up and down direction when the apparatus is installed in a vehicle is indicated by arrows.




As shown in FIG.


8


and

FIG. 9

, the latching apparatus


200


of this embodiment comprises a tongue


210


and a buckle


240


. Disposed below the buckle


240


is an anchor bracket


205


.




The tongue


210


has an outer casing


212


. The tongue


210


is provided at its lower end with a tongue plate


211


which is inserted into the buckle


240


. The tongue plate


211


is latched to a tongue latching mechanism


250


of the buckle


240


. A hanger portion


213


is arranged inside the casing


212


. The hanger portion


213


has a slit


213




a


through which the lap webbing


41


is passed just like the aforementioned embodiment.




In the casing


212


, a tongue pipe


215


is disposed on a side of the tongue plate


211


and the hanger portion


213


. The tongue pipe


215


is fixed to the casing


212


by rivets


216


. The gas inlet


77


of the bag is connected to the upper end of the tongue pipe


215


by a band


217


in the same manner as the aforementioned embodiment. The inside of the tongue pipe


215


communicates with the inside of the bag in the same manner as the aforementioned embodiment described above. The lower end of the tongue pipe


215


projects outside the casing


212


. A tongue cap


218


made of aluminum is fitted on the lower end opening of the tongue pipe


215


. This tongue cap


218


has a bottom


218




a


formed in a concave spherical shape. The bottom


218




a


is formed with tear lines. The tongue cap


218


also functions as a screen gate or protective cover for preventing dust from invading into the tongue pipe


215


.




The buckle


240


has an outer casing


242


. The casing


242


is formed at its upper portion with an upper opening


242




a


into which the tongue plate


211


is inserted. The tongue latching mechanism


250


for latching the inserted tongue plate


211


is disposed in the casing


242


. A release button


242




b


is provided at the upper portion of the casing


242


. As the button


242




b


is depressed, the tongue latching mechanism


250


is released so as to pushed out the tongue


210


upwardly.




The tongue latching mechanism


250


functions in the same basic manner as the tongue latching mechanism


110


described above.




A buckle pipe


245


is disposed on a side of the tongue latching mechanism


250


of the buckle


240


(on the lower side in

FIG. 8

, on the left side in FIG.


9


). The buckle pipe


245


is fixed to a retainer


249


inside the casing


242


by rivets


244


. A buckle cap


248


made of aluminum is fitted on the upper end of the buckle pipe


245


. The buckle cap


248


has a top surface


248




a


which is formed in a convex spherical shape. The top surface


248




a


is formed with tear lines.




As shown in FIGS.


11


(A) and


11


(B), the inner diameter R of the buckle pipe


245


, the inner diameter R′of the tongue pipe


215


, and the inner diameter R″ of the buckle cap


248


are designed to be equal (for example, 9.6 mm). There is a clearance or gap (over stroke) C between the inner surface of the buckle cap


248


and the upper end of the buckle pipe


245


as shown in FIGS.


10


(A) through


10


(C). The clearance C absorbs the tolerance among parts and backlash during the insertion or tilting of the tongue


210


. The buckle cap


248


is biased upwardly by a spring


255


fitted around the buckle pipe


245


. Because of the biasing force of the spring


255


, the upper end of the buckle pipe


245


and the lower end of the tongue pipe


215


are closely in contact with each other when the tongue


210


is latched (in the state shown in FIG.


9


).




In the casing


242


of the buckle


240


, the upper end of the inflator


239


is connected to the lower end of the buckle pipe


245


. The inflator


239


includes a propellant, an initiator (not shown) therein. As the inflator


239


is ignited in the event of vehicle collision, the inflator


239


produces gas for deploying the bag into the buckle pipe


245


. The gas passes into the hollow portion of the bag through the tongue pipe


215


of the tongue


210


after passing through the inside of the buckle pipe


245


.




This embodiment is designed so that the tongue pipe


215


of the tongue


210


and the buckle pipe


245


of the buckle


240


are substantially coaxially aligned and connected to each other at the side of the latching apparatus


200


when the tongue


210


is latched (in the state shown in FIG.


9


). The bottom


218




a


of the tongue cap


218


beneath the lower end of the tongue pipe


215


and the top


248




a


of the buckle cap


248


of the buckle pipe


245


are in closely contact with each other because of the concave spherical shape of the bottom


218




a


and the convex spherical shape of the top


248




a


as clearly shown in FIG.


10


(A). The buckle cap


248


is biased toward the tongue cap


218


by the spring


255


. Therefore, the space between the pipes


215


,


245


is eliminated.




When the tongue


210


tilts rightward relative to the buckle


240


, as shown in FIG.


10


(B), the tongue pipe


215


and the buckle pipe


245


have a tilt angle therebetween so that the tongue pipe


215


and the buckle pipe


245


are not coaxially arranged. However, at this point, the bottom


215




a


of the tongue pipe


215


having the concave spherical shape is followed by the top


245




a


of the buckle pipe


245


because the top


245




a


has the convex spherical shape that is hard to deform against outer force from the above. The same is true for a case that the tongue


210


tilts leftward relative to the buckle


240


as shown in FIG.


10


(C). Therefore, even when there is a tilt between the tongue pipe


215


and the buckle pipe


245


, no space is created between the caps


218


and


248


. It should be noted that the tilt of the buckle cap


248


itself is absorbed by the clearance C in the cap.




The joint portion between the tongue pipe


215


and the buckle pipe


245


is normally closed by the respective caps


218


,


248


as shown in FIG.


11


(A). However, when the inflatable belt is actuated, the caps


218


,


248


are broken along their tear lines by gas pressure produced by the inflator


239


. During this, the clearance at the joint portion is further compressed by the pressure of the gas, thus further reducing the possibility of gas leakage during the actuation of the inflator


239


. After the caps


218


,


248


are broken along their tear lines so as to allow the communication between the tongue pipe


215


and the buckle pipe


245


, the gas from the inflator


239


is supplied into the bag through the inside of the pipes.




Since the inner diameter of the pipes


215


,


245


, and the inner diameter of the buckle cap


248


are equal (R=R′=R″), the flow passage area at the upstream (the tongue pipe


215


) side and the flow passage area at the downstream (the buckle pipe


245


) side relative to the joint portion of the caps


218


,


248


are constant. Even when there is a tilt between the tongue pipe


215


and the buckle pipe


245


, no space is created at the joint portion thereof as mentioned above. Therefore, there is no possibility of turbulence generation in the gas flowing inside the pipes so that the gas can smoothly flow and the gas can reach the inside of the bag without delay.




Description will now be made as regard to a variation of caps with reference to FIG.


12


through FIG.


13


(C).




A buckle cap


348


shown in these drawings has a top


348




a


formed in a convex shape having a tapered surface. On the other hand, a tongue pipe cap


318


has a bottom


318




a


formed in a concave shape having a tapered surface. The top


348




a


and the bottom


318




a


are formed with tear lines, respectively, just like the aforementioned embodiments.




According to the buckle cap


348


and the tongue pipe cap


318


having such tapered surfaces, even when the buckle pipe


245


and the tongue pipe


215


are shifted from each other as shown in FIG.


13


(A), the tapered surfaces of the caps


318


,


348


slide relative to each other as shown in FIG.


13


(B) so that the caps


318


,


348


are aligned with each other about the center as shown in FIG.


13


(C). Therefore, no space is created at the joint portion between the buckle pipe


245


and the tongue pipe


215


.




As apparent from the above description, the present invention can provide a latching apparatus for an inflatable belt device which achieves reduction in the gas leakage without losing the smoothness of insertion of a tongue into a buckle, or which achieves reduction in the manufacturing cost and the weight of the latching apparatus.




When the inner diameter of the buckle pipe cap is designed to have substantially the same diameter as the inner diameter of the tongue pipe and the buckle pipe, the flow passage area at the tongue pipe side and the flow passage area at the buckle pipe side are constant. Therefore, there is no possibility of turbulence generation in gas flowing from the inflator to the inside of the bag so that the gas can smoothly flow.




When the top of the buckle pipe cap is formed in a convex spherical shape and the bottom of the tongue pipe cap is formed in a concave spherical shape corresponding to the configuration of the top of the buckle pipe cap, or when the top of the buckle pipe cap is formed in a convex shape having a tapered surface and the bottom of the tongue pipe cap is formed in a concave shape having a tapered surface corresponding to the configuration of the top of the buckle pipe cap, even if there is tilt between the tongue pipe and the buckle pipe, the lower end of the tongue pipe is followed by the upper end of the buckle pipe and these are aligned with each other about the center. Therefore, no space is created at the joint portion between the pipes.




The priority documents, Japanese Patent Application No. 2000-56621 filed Mar. 2, 2000 and No. 2000-347772 filed Nov. 15, 2000 are incorporated by reference herein in their entirety.



Claims
  • 1. A latching apparatus for an inflatable belt device comprising:a tongue having a tongue pipe and being connected to an end of an inflatable belt; a buckle having a buckle pipe and configured for being latched together with the tongue; wherein the tongue pipe and the buckle pipe are configured to be substantially coaxially aligned and connected to each other when the tongue is latched to the buckle, so that gas for deploying the inflatable belt may pass from the buckle to the tongue, and wherein a connecting member is provided between the pipes, the connecting member biased in a direction from the buckle toward the tongue to eliminate a space between the pipes.
  • 2. The latching apparatus of claim 1, wherein said connecting member comprises:a buckle pipe cap which is fitted on the upper end of said buckle pipe and is configured to break when an inflator is actuated, and a spring for biasing the buckle pipe cap into contact with the lower end of the tongue pipe.
  • 3. The latching apparatus of claim 2, wherein the inner diameter of said buckle pipe cap is substantially equal to the inner diameter of said tongue pipe and said buckle pipe.
  • 4. The latching apparatus or claim 3, wherein said connecting member further comprises a tongue pipe cap which is fitted on the lower end of said tongue pipe and is configured to rupture when the inflator is actuated.
  • 5. The latching apparatus of claim 4, wherein the top of the buckle pipe cap is formed in a convex shape and the bottom of said tongue pipe cap is formed in a concave shape.
  • 6. The latching apparatus of claim 4, wherein the top of said buckle pipe cap is formed in a convex spherical shape and the bottom of said tongue pipe cap is formed in a concave spherical shape corresponding to the configuration of the top of said buckle pipe cap.
  • 7. The latching apparatus of claim 4, wherein the top of said buckle pipe cap is formed in a convex shape having a tapered surface and the bottom of said tongue pipe cap is formed in a concave shape having a tapered surface corresponding to the configuration of the top of said buckle pipe cap.
Priority Claims (2)
Number Date Country Kind
2000-056621 Mar 2000 JP
2000-347772 Nov 2000 JP
US Referenced Citations (13)
Number Name Date Kind
3682498 Rutzki Aug 1972 A
3791670 Lucore et al. Feb 1974 A
3929348 Lawwill Dec 1975 A
5385367 Tanaka et al. Jan 1995 A
6019388 Okazaki et al. Feb 2000 A
6062597 Suyama May 2000 A
6082763 Kokeguchi Jul 2000 A
6116637 Takeuchi et al. Sep 2000 A
6126194 Yaniv et al. Oct 2000 A
6142512 Suyama Nov 2000 A
6168196 Nariyasu Jan 2001 B1
6220626 Utsumi et al. Apr 2001 B1
6237946 Nariyasu May 2001 B1
Foreign Referenced Citations (2)
Number Date Country
406262997 Mar 1993 JP
405112201 May 1993 JP