Knee air bag for vehicle

A knee air bag for a vehicle has an inflator, a diffuser and a cushion to protect a passenger's knee when the cushion is deployed. The knee air bag also includes an inflator connector which is provided on a back of the cushion, and an external tether which is provided on an upper portion of the inflator connector and secured at lower and upper ends thereof to the back of the cushion, thus guiding the cushion so that the cushion is deployed upwards. The knee air bag makes the cushion come into close contact with a seatback of the vehicle when the knee air bag is deployed, thus reducing interference with a roof air bag located at an upper position, therefore preventing a passenger's head or neck from suffering secondary injuries.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Korean Patent Application No. 10-2010-0116687 filed on Nov. 23, 2010, the entire contents of which application is incorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a knee air bag for a vehicle, which is provided in front of a seat of the vehicle to be deployed in the event of a collision, thus protecting a passenger's knees.

2. Description of the Related Art

Recently, as the interest given to safety in the event of a vehicle collision has increased, a vehicle has been equipped with various air bags to effectively protect a passenger during the vehicle collision.

Among the air bags, as one example, a knee air bag has been proposed. However, the knee air bag has not been widely installed in vehicles, in comparison with other air bags.

Thus, recently, a lot of research into the knee air bag has been made, but there has not yet been proposed a knee air bag whose shape and structure are designed in consideration of relations between the knee air bag and other air bags.

The knee air bag is generally deployed around the lower part of a passenger's body to protect his or her knees in the event of a collision. The upper part of the passenger's body is protected by a center air bag or a roof air bag. Thus, in order to reliably protect the upper part of the passenger's body and his or her knees, the layout of the knee air bag with respect to the roof air bag or the like when the knee air bag is deployed must be considered.

For example, referring toFIGS. 1 and 2, as for the rear seat of a vehicle, in the event of a collision, a roof air bag10is deployed to protect the head and chest of a passenger P, while a knee air bag30is deployed at a lower position to protect the knees of the passenger P. However, the two air bags are simultaneously deployed, so that the upper end of the knee air bag30is pressed against the lower end of the roof air bag10, and thus the roof air bag10may excessively protrude towards the passenger P. This causes the twisting of his or her neck, thus undesirably increasing secondary injuries.

Such an increase in secondary injuries occurs for the following reason. That is, when the knee air bag30is deployed, an inflator explodes and simultaneously a cushion of the air bag is excessively deployed towards the passenger P, so that the roof air bag10located at an upper position is pushed by the knee air bag30and is excessively deployed towards the passenger P. Thus, when the knee air bag30is applied in the same manner as the conventional air bag, it has a problem in that secondary injuries increase. Therefore, there is required a knee air bag having an optimum shape and structure which can reduce the injuries and minimize interference with another bag to allow the two air bags to sufficiently display their effects.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and an object of the present invention is to provide a knee air bag for a vehicle, which avoids interference with a roof air bag when the knee air bag is deployed, thus preventing a passenger from being secondarily injured by the air bag.

Another object of the present invention is to provide a knee air bag for a vehicle, which is deployed as rapidly as possible and reliably maintains its deployed shape.

In order to achieve the above objects, according to one aspect of the present invention, there is provided a knee air bag for a vehicle having an inflator, a diffuser and a cushion to protect a passenger's knee when the cushion is deployed. The knee air bag includes an inflator connector which is provided on a back of the cushion, and an external tether which is provided on an upper portion of the inflator connector and secured at lower and upper ends thereof to the back of the cushion, thus guiding the cushion so that the cushion is deployed upwards.

The external tether may have a shape of a band of a predetermined width, and a length between the upper and lower ends of the external tether secured to the cushion may be formed to be shorter than a length of an associated portion of the cushion, so that, when the cushion is deployed, the cushion is pulled in a direction opposite to a passenger.

The lower end of the external tether may be secured to a position adjacent to the inflator connector of the cushion, and the upper end of the external tether may be secured to an upper end or an upper portion of a front of the cushion.

The cushion may be formed such that a width thereof is reduced in a direction from a lower end to an upper end thereof.

An upper portion of the cushion may have a trapezoidal shape, and a lower portion of the cushion may have a rectangular shape, so that the cushion may have an overall hexagonal shape.

The diffuser may be provided in the cushion to be connected to the inflator, and may have a shape of a chamber which has a closed curved surface independent of the cushion, with a plurality of vent holes formed along a circumference of the chamber.

The knee air bag may further include a vertical tether which is provided on a side of the diffuser in such a way as to be placed vertically and connects the front and the back of the cushion to each other in the cushion.

The knee air bag may further include a horizontal tether which is provided on an upper portion of the diffuser in such a way as to be placed horizontally and connects the front and the back of the cushion to each other in the cushion, a rear end of the horizontal tether which is connected to the back of the cushion being connected to the upper end of the external tether.

The diffuser may be provided in the cushion to be connected to the inflator, may have a shape of an inverted “Y”, and may include an upper vent part which extends vertically and a pair of lower vent parts which extend diagonally.

The knee air bag may further include a vertical tether which is provided on a side of the upper vent part of the diffuser in such a way as to be placed vertically and connects the front and the back of the cushion to each other in the cushion.

The knee air bag may further include a horizontal tether which is placed horizontally between the lower vent parts provided on both sides of the diffuser and connects the front and the back of the cushion to each other in the cushion.

DETAILED DESCRIPTION

FIG. 3is a perspective view showing a deployed knee air bag for a vehicle according to various embodiments of the present invention,FIG. 4is a front view showing the knee air bag for the vehicle ofFIG. 3,FIG. 5is a rear view showing the knee air bag for the vehicle ofFIG. 3, andFIG. 6is a side view showing the knee air bag for the vehicle ofFIG. 3.

The knee air bag for the vehicle according to various embodiments of the present invention includes an inflator I, a diffuser400and a cushion100, and functions to protect a passenger's knees when the cushion100is deployed. The knee air bag includes an inflator connector C which is provided on the back of the cushion100, and an external tether300which is provided on the upper portion of the inflator connector and is secured at lower and upper ends thereof to the back of the cushion100to upwardly guide the deployment of the cushion100.

The knee air bag for the vehicle may be provided for passengers sitting in front and rear seats of the vehicle. The following will be described with reference to the case wherein the knee air bag is provided for a passenger sitting in the rear seat.

The knee air bag for the vehicle includes the inflator I, the diffuser400, the cushion100and the external tether300attached to the cushion100. They form one module and may be provided on a seatback S of the front seat of the vehicle. In the event of a collision, the cushion100may be deployed upwards along the seatback S by the explosion of the inflator I.

The cushion100is fitted with the external tether300. The external tether300is provided above a portion of the cushion100to which the inflator I is connected, and is secured at each of the lower and upper ends to the back of the cushion100, thus upwardly guiding the deployment of the cushion100. The external tether300prevents the cushion100of the air bag from being deployed directly from the seatback S to a passenger, but allows the cushion100to be deployed upwards along the seatback S. Thus, the knee air bag does not interfere with the lower end of the roof air bag10which is located at an upper position, thus preventing secondary injuries, that is, the twisting of a passenger's neck or head.

Meanwhile, the external tether300has the shape of a band having a predetermined width, and is formed such that a length between the upper and lower ends of the external tether300secured to the cushion100is shorter than a length of an associated portion of the cushion100, and thus the cushion100is pulled in a direction opposite to a passenger when the cushion100is deployed.

The external tether300, which has the shape of a band having a predetermined width, may be made of the same material as the cushion100of the air bag, and may be formed to be shorter than the entire length of a portion of the cushion100to which the external tether300is attached, so as to maintain an effective pulling force. That is, the external tether300is secured at the upper and lower ends thereof to the back of the cushion100. By making the length of a portion of the cushion100to which the external tether300is attached be longer than a length between the upper and lower ends of the external tether300, the external tether300may sufficiently pull the cushion100in response to the expansive force of the cushion100. Since the external tether300has the above-mentioned shape, the cushion100is wrinkled at a position to which the external tether300is attached, when the cushion100is deployed (seeFIG. 6).

Further, the lower end of the external tether300may be secured to a position adjacent to the inflator connector of the cushion100, while the upper end of the external tether300may be secured to the upper end or the upper portion of the front of the cushion100.

That is, the lower end of the external tether300may be secured to a position adjacent to the inflator connector of the cushion100, and the securing position of the upper end may be changed to the upper end or the upper portion of the front of the cushion100, depending on the amount of pulling force that is set.

The width of such a cushion100may be formed such that it is reduced in a direction from a lower end to an upper end thereof. Since the cushion100is not shaped into a general rectangle but is shaped to become narrow towards the upper end, the unnecessary space of the cushion100is reduced, and thereby a proper expansive force of the cushion100is attained. The reason for this is because the explosive force of gas supplied from the inflator I is restrictive and a sufficient space is required for only a portion making contact with a passenger's knees N in the case of the knee air bag. Further, since the volume of the cushion100is reduced in a direction from the lower end to the upper end thereof, a larger deploying force is attained in an upward direction. Owing to rapid upward deployment, the knee air bag does not collide with the lower end of the roof air bag10but is in close contact with the seatback S of the vehicle.

The upper portion of the cushion100may have a trapezoidal shape and the lower portion of the cushion100may have a rectangular shape, so that the cushion100has a hexagonal shape overall. Such a shape was determined based on an experiment. This shape enables the air bag cushion100to have a top101, a pair of upper side surfaces102and102′, a pair of lower side surfaces103and103′, and a bottom104.

Meanwhile, the diffuser400is provided in the cushion100in such a way as to be connected to the inflator I, and has the shape of a chamber which has a closed curved surface independent of the cushion100. The diffuser400includes a plurality of vent holes420which are formed along the circumference of the chamber.

The construction of the diffuser400shaped in this way is novel. The diffuser400has the shape of the closed curved surface defining an independent chamber in the air bag cushion100, and includes the vent holes420formed along the circumference of the chamber, thus allowing gas G to be evenly distributed in the cushion100. Further, the diffuser400prevents high-temperature and high-pressure gas of the inflator I from being directly jetted to the cushion100, thus improving the durability of the air bag cushion100. Thus, the gas G of the inflator I is first supplied to the diffuser400. While the diffuser400is expanding, the gas is jetted through the vent holes420in all directions, thus resulting in the inflation of the air bag cushion100.

Meanwhile, the knee air bag may further include a vertical tether202and a horizontal tether201. The vertical tether202is vertically installed on a side of the diffuser400to connect the front and back of the cushion100to each other in the cushion100. The horizontal tether201is horizontally installed at an upper position of the diffuser400to connect the front and back of the cushion100to each other in the cushion100. The rear end of the horizontal tether201connected to the back of the cushion100is connected to the upper end of the external tether300.

As shown inFIG. 4, a pair of vertical tethers202and203may be provided on opposite sides of the cushion100along the circumference of the circular diffuser400, and one horizontal tether201may be provided on the upper portion of the diffuser400. These internal tethers200connect the front and back of the cushion100to each other in the cushion100, thus limiting the inflation of the cushion100so that the thickness of the cushion is constant when the cushion100is inflated. Further, the horizontal tether201is provided on the upper portion of the diffuser400to allow the gas G jetted through the diffuser400to sufficiently flow to a lower position, thus allowing a portion of the cushion100making contact with a passenger's knees N to rapidly inflate. Meanwhile, the upper portion of the cushion100is filled with gas which is discharged through gaps between the internal tethers200. Since the width of the upper portion of the cushion100is gradually reduced, it can be seen that a sufficient deploying speed is achieved even at the upper portion.

Further, as shown inFIGS. 5 and 6, the rear end of the horizontal tether201attached to the back of the cushion100is connected to the upper end of the external tether300, so that the external tether300pulls the front of the cushion100as well as the back of the cushion100, thus allowing the upper portion of the cushion100to be in strong and close contact with the seatback S.

Meanwhile,FIG. 7shows a cushion having a diffuser according to various embodiments of the present invention. The following diffuser is denoted by reference numeral500so as to be distinguished from the above embodiment. One will appreciate, however, that various aspects of the following diffuser may be similar to that described above.

The diffuser500is provided in the cushion100to be connected to the inflator I, and has the shape of an inverted “Y”. The diffuser500includes an upper vent part560which extends vertically, and a pair of lower vent parts520and540which extend diagonally. Further, the knee air bag includes vertical tethers202and203which are vertically placed on opposite sides of the upper vent part560of the diffuser500to connect the front and back of the cushion100to each other in the cushion100, and a horizontal tether204which is horizontally placed between the lower vent parts520and540provided on both sides of the diffuser500and connects the front and back of the cushion100to each other in the cushion100.

Such a diffuser500has the shape of an inverted “Y”, and includes the upper vent part560and the pair of lower vent parts520and540. The lower vent parts520and540jet gas downwards in a diagonal direction, thus promoting the inflation of the lower portion of the cushion100, therefore allowing a passenger's knees to be sufficiently protected. Further, the upper vent part560vertically jets gas, thus allowing the upper portion of the cushion100to be rapidly inflated.

Meanwhile, the horizontal tether204is horizontally provided between both the lower vent parts520and540, so that it controls the thickness of the cushion100and does not hinder the gas jetting operation of the upper vent part560.

FIG. 8is a view showing an initial deployment stage of the knee air bag for the vehicle ofFIG. 3, andFIG. 9is a view showing a latter deployment stage of the knee air bag for the vehicle ofFIG. 3.

Referring to the drawings, in the event of a collision, the cushion100of the knee air bag is not deployed towards a passenger as in the prior art, but is deployed upwards along the seatback. Thereby, the lower end of the roof air bag10located at an upper position does not collide with the upper end of the knee air bag, but is deployed in such a way as to cover the upper end of the knee air bag cushion100, thus preventing the roof air bag10from excessively protruding towards the head of a passenger P, therefore preventing the passenger P from suffering secondary injuries.

As described above, the present invention provides a knee air bag for a vehicle, which makes a cushion come into close contact with a seatback of the vehicle when the knee air bag is deployed, thus reducing interference with a roof air bag located at an upper position, therefore preventing a passenger's head or neck from suffering secondary injuries.

Further, the present invention includes a novel cushion shape, tether structure and diffuser construction, which allow the knee air bag to be deployed within a sufficiently short period of time.