Device and method for personal protection in vehicles

Abstract: The invention relates to a device for personal protection in vehicles, comprising an airbag (9; 9') which in its inactive condition is arranged in a space in connection with a dashboard (1) of the vehicle and in its active condition extends essentially in front of the legs and knees of an occupant in the vehicle, a sensor for detection of a condition generally corresponding to a collision, and means (10; 18) for inflating the airbag (9; 9') when the sensor detects that said condition prevails. The invention is characterized in that the device comprises a load-distributing element (17) which cooperates with the airbag (9; 9') in said active condition for distributing a load from the occupant (20), said load-distributing element (17) being constituted by a predetermined section of the airbag (9') which is designed with a stiffness which exceeds the stiffness of the remainder of the airbag (9'). The invention also relates to a method for personal protection in vehicles. The invention provides an improved airbag arrangement for protection of the knees, the lower parts of the legs and the feet of occupants in a vehicle.

Description: TECHNICAL FIELD: The present invention relates to a device for personal protection in a vehicle, according to the preamble of appended claim 1. Such a device is known from closest prior art document DE-A- 3908713. The invention also relates to a method for personal protection in a vehicle, according to the preamble of appended claim 10. In particular, the invention is intended for use in the field of airbags which are used for protection of occupants of motor vehicles. BACKGROUND OF THE INVENTION: In the field of motor vehicles, inflatable airbags are often used for protection of occupants in vehicles in the event of a collision or the like. In the case where such an airbag is used to protect the driver of the vehicle, it is normally arranged in the hub of the steering wheel. In the case where it is used to protect a passenger in the passenger seat of the vehicle, its is normally arranged in connection with the upper part of the dashboard and in front of the passenger seat. Should a collision occur, the airbags are activated by inflating them by means of a gas generator. In the field of the motor vehicles, there is also a need to protect body parts other than the head and the upper torso. The technology forming the basis of airbags may then be employed so as to protect for example knees and legs of vehicle occupants. Following this requirement, devices comprising airbags for use as knee protecting devices have been developed. Such a device is previously known from US-A-5312131 and comprises an airbag module with two airbags which are arranged under the central console of the dashboard, between the driver's seat and the passenger seat. In the event of a collision, one of the airbags will be inflated in a direction towards the driver, whereas the other airbag will be inflated in the direction towards the passenger. This known device is associated with a problem as regards the fact that it is not arranged so as to take account of how the occupant is seated and the size of the occupant. For example, if an occupant has relatively long legs (or if the occupant has positioned the seat in a far forward position), the airbag will not be positioned between the dashboard and the occupant during inflation, which is the desired procedure, but instead the airbag will impinge on the legs of the occupant from the side. This implies that the legs will be pushed away in the sidewards direction, which in turn results in that the device will not provide the desired protection. Another similar device, which is previously known from GB-A-2263671, comprises an essentially flat airbag forming an elongated unit which is arranged under the dashboard and which extends across the legs of the passenger. A problem involved with this device is that it is mounted on the outside of the dashboard, which is a disadvantageous position as regards the space available in the vehicle. Furthermore, the airbag is inflated in a direction which essentially forms a right angle with the backing support panel, which limits the possibility of absorbing and distributing the force which acts upon the airbag during a collision. Another problem in connection with airbag system for the lower parts of the legs and for the knees is that point-shaped loads often arise, for example during penetration of the occupant's knees in such an airbag. Consequently, there is a risk that for example the knees of the occupant are pressed too deep into the airbag during a collision. This makes it difficult to obtain the desired energy-absorbing effect, especially since an airbag for knees and legs is considerably smaller than a conventional airbag for the upper torso of an occupant, which in turn and amongst other things is due to the fact that the distance between an upper torso airbag and the occupant's upper torso is considerably greater than the distance between an occupant's legs and an airbag designed for the legs. SUMMARY OF THE INVENTION: A main object of the present invention is thus to solve the above-mentioned problems and to provide an improved device which comprises an airbag which can be inflated in an optimum manner as regards the protection of the knees, the lower parts of the legs and the feet of occupants in a vehicle, and which can be arranged in an effective manner, as regards the space available, in connection with the dashboard of the vehicle. This is accomplished by means of a device as initially mentioned, the characterizing features of which will be apparent from claim 1. Said object is also accomplished by means of a method as initially mentioned, the characterizing features of which will be apparent from claim 10. The invention constitutes a device for personal protection in vehicles, comprising an airbag which in its inactive condition is arranged in a space in connection with a dashboard of the vehicle and in its active condition extends essentially in front of the legs and knees of an occupant in the vehicle, a sensor for detection of a condition generally corresponding to a collision, and means for inflating the airbag when the sensor detects that said condition prevails. According to the invention, there is provided a load-distributing element which cooperates with the airbag in said active condition for distributing a load from the occupant, said load-distributing element being constituted by a predetermined section of the airbag which is designed with a stiffness which exceeds the stiffness of the remainder of the airbag. The invention also constitutes a method for personal protection in a vehicle comprising an airbag which in its inactive condition is arranged in connection with a dashboard, comprising detection by means of a sensor of a condition of the vehicle which generally corresponds to a collision, and activation of the airbag if said condition prevails. According to the invention, said method comprises controlling said activation so that the airbag is expanded to a position which is essentially directly in front of the legs and knees of an occupant in the vehicle, and so that a load acting upon the airbag by said occupant is absorbed and distributed by means of a load-distributing element which is arranged as a predetermined section of the airbag which is designed with a stiffness which exceeds the stiffness of the remainder of the airbag. By using a particular load-distributing element which absorbs and distributes the load acting upon the airbag, improved protection can be provided. The load-distributing element is constituted by an element forming part of the airbag. Furthermore, due to the fact that the airbag can be arranged behind the dashboard in its inactive condition, advantages as regards the space available in the passenger compartment can be obtained. Due to the fact that the airbag, in its inactive condition, is arranged as an elongated unit which is arranged essentially perpendicular to the longidudinal direction of the vehicle, only small packing dimensions will be required in a section of the vehicle which otherwise offers very little available space. According to a specific embodiment, the invention comprises a lid which is folded down in the car when the airbag is activated. This results in a minimal risk of leg injuries for the passenger. According to another embodiment, the invention comprises an airbag which is supported inside the lid of the glove compartment. In this regard, the airbag is designed with a special load-distributing element which is adapted so that it will be positioned between the airbag and an occupant in the vehicle when the airbag is activated. By means of this load-distributing element, the load acting on the airbag during for example a collision can be absorbed. In particular, the impact area is stiffened where for example the occupant's knees impact the airbag, whereby the load which acts on the airbag can be absorbed and distributed. The point-shaped loads which arise following penetration of for example the occupant's knees in the airbag can thus be distributed in an effective manner. This results in turn in improved protection for the passenger. The basic principle of the invention is that energy absorption takes place in the airbag. In the case where the airbag is inflated to a position outside the glove compartment, a load-distributing element is provided, which element is arranged in connection with, or is integrated with, the airbag. BRIEF DESCRIPTION OF THE DRAWINGS: The invention will be described in greater detail in the following with reference to the annexed drawings, in which Fig. 1 is a perspective view showing a vehicle passenger compartment provided with an airbag arrangement in accordance with the present invention, which airbag arrangement is in its non-inflated state, Fig. 2 is a side view showing the invention according to a first embodiment, Fig. 3 is a cross-section view through a glove compartment according to a second embodiment of the invention, Fig. 4 is a perspective view of the door of the glove compartment according to the second embodiment, and Fig. 5 is a side view showing the invention in its active position, according to the embodiment shown in Figs. 3 and 4. PREFERRED EMBODIMENTS: Fig. 1 shows a perspective view of a vehicle passenger compartment provided with an airbag arrangement in accordance with the present invention. In the compartment a dashboard 1, a steering wheel 2 and a centre console 3 are provided in a conventional manner. On the passenger side of the compartment, a glove compartment 4 provided with an openable lid 5 is arranged. Preferably, the lid 5 has a rounded shape and can be opened by pivoting it about an axis which is defined by a hinge device 6 along the lower edge of the lid 5. The lid 5 transforms into a lower panel 7 of the dashboard 1. The lower panel 7 transforms in turn into the section of the vehicle body which forms the floor 8 of the vehicle. Furthermore, the dashboard 1 is preferably arranged so that the lid 5 is positioned directly in front of the position in which a passenger normally places his knees. The glove compartment 4, the lid 5 and the lower panel 7 extend in the sidewards direction from the centre console 3 to the edge of the dashboard 1 which is adjacent to the vehicle door (not shown) on the passenger side. An airbag 9 is arranged on the reverse side of the lower panel 7, preferably in a space arranged just below the lid 5 of the glove compartment 4. In the inactive condition of the airbag 9 (i.e. in its non-inflated condition), it has an elongated disposition which is essentially perpendicular to the longitudinal direction of the vehicle. Fig. 1 shows the airbag 9 in this condition. The airbag 9 is per se of conventional kind and is therefore not described in detail. An inflation device is arranged in connection with the airbag 9, which device is preferably in the form of a gas generator 10 which is adapted for inflating the airbag 9 should a collision occur. To this end, the gas generator 10 is connected to an acceleration sensor (not shown) which in a known manner is adapted to detect whether a particularly high retardation occurs. If this is the case, the acceleration sensor emits a signal to the gas generator 10, which in turn will be activated so as to inflate the airbag 9. The airbag 9 is mounted in an essentially elongated support bracket 11 which in turn is fixed in the vehicle on the reverse side of the dashboard 1, preferably behind the lower panel 7. The gas generator 10 is also mounted on the support bracket 11. In accordance with what is illustrated in detail in Fig. 2, the airbag 9 is arranged behind an opening 12 in the lower panel 7. This opening 12 is covered by an elongated lid 13 which is pivotally mounted by means of hinges 14 in the lower edge of the lid 13. This means that when the airbag 9 is activated, it will influence the lid 13 outwardly due to the pressure inside the airbag, so as to swing the lid 13 about the hinges 14 and thereby opening it. This results in that the airbag 9 is forced out into the vehicle passenger compartment, in front of the legs of the passenger. For the purpose of forcing out the airbag 9 in an optimum manner, the airbag 9 and the gas generator 10 are preferably arranged in a slightly inclined manner, i.e. so that the airbag 9 during its inflation is "directed" essentially parallel to the lower parts of the passenger's legs. Fig. 2 shows the device according to this first embodiment, the airbag 9 being in its activated, inflated condition. Although the airbag 9 essentially is of a conventional type, it is adapted as regards the shape and sewing thereof to the space which is formed in front of the legs and knees of the passenger, i.e. the space in front of the glove compartment 4 and the lower panel 7. Furthermore, the airbag 9 extends laterally in a direction which essentially corresponds to the width of the lower panel 7 (see also Fig. 1). In this manner, effective protection can be obtained. Preferably, the airbag 9 has a volume of approximately 10-20 litres. When the legs of the occupant hit the inflated airbag 9 during a collision, a high force is exerted upon the airbag 9. The gas inside the airbag 9 contributes to energy absorption, i.e. said force from the occupant's body will be absorbed. In order to further improve this force-absorbing and load-distributing effect, the dashboard 1 is arranged so that a certain part of its surface constitutes a load-distributing element in the form of a surface which is arranged essentially directly in front of the legs of the occupant. In the event of a collision, the force acting upon the airbag 9 will be transferred to this surface, whereby the force will be absorbed and distributed along the surface. In this manner, the impact on the occupant can be reduced. Preferably, this load-distributing element is formed by the lid 5 of the glove compartment 4. According to the invention, the lid 5 is thus positioned essentially directly in front of the knees and lower parts of the legs of the occupant, i.e. at the position which is exposed to a high impact in the event of a collision. In this manner, the "built-in" flexibility of the lid 5 of the glove compartment 4 can be used to even out the impact on the exposed body parts of the occupant. In order to obtain a significant distribution of the load, the lid 5 can be manufactured from a particularly selected material. For example, the lid 5 can be manufactured from a layer of ABS plastic, metal sheet, aluminium sheet or similar material having a certain elasticity as regards impact absorption. In order to further improve its properties, the lid 5 can be manufactured from a sandwich design which can comprise several material layers (for example three or more) which can be arranged according to the type plastic/metal/plastic. When the airbag 9 is inflated, it is forced out of the opening 12 and is formed so as to be positioned between the door 5 and the legs of the occupant. During inflation, the airbag 9 is developed in a direction which is inclined slightly upwards and rearwards, i.e. essentially parallel to the normal direction of an occupant's legs. In this manner, the airbag 9 will always be situated between the lid 5 and the legs of the occupant in a collision, even if the occupant has placed his legs in a far advanced position. The direction of the expansion of the airbag preferably forms an angle of 20-70° in relation to the longitudinal direction of the vehicle. It is not necessary to provide a glove compartment 4 with a lid 5 in order to maintain an impact absorbing element. In vehicles lacking a glove compartment or in which a glove compartment is provided elsewhere in the vehicle, the dashboard may include an outer wall which comprises a particular section forming said impact-absorbing element. Preferably, the airbag is designed with a plurality of ventilation holes (not shown) assuring that the pressure in the airbag 9 is released with an even flow when a force is applied to the lid 5, which in turn distributes the load along the airbag 9. An additional embodiment of the invention is shown in Figs. 3, 4 and 5. These figures too show the principle of a load-distributing element which can absorb and distribute the impact acting on an airbag during a collision. Fig. 4 shows a cross-section through a dashboard 1 with a glove compartment comprising a lid 5'. According to the embodiment, the lid 5' is designed so as to support and accommodate an airbag 9'. To this end, the lid 5' comprises a base panel 15 and a front panel 16, wherein the base panel 15 is designed so as to be stronger than the front panel 16. Between these panels 15, 16, a space is formed, which consequently accommodates the airbag 9'. In its inactive condition, the airbag 9' is folded so that it assumes a thin and essentially sheet-like shape having dimensions, as regards its height and width, which correspond to the assumed position of the lower parts of the legs and the knees of an occupant in the vehicle. Since an airbag for the present field of use can be manufactured with a relatively small volume, approximately 20-25 litres, it can be folded to a relatively small size, i.e. so as to accommodate it within the lid 5'. The airbag 9' is provided with a load-distributing element 17 which is arranged to be positioned between the airbag 9' and the occupant in the vehicle when the airbag 9' is activated. The load-distributing element 17 differs from the load-distributing element 5 described above as regards the fact that it constitutes a part of the airbag 9' rather than a part of the dashboard of the vehicle. The load-distributing element 17 according to Fig. 3 can be designed in many different ways, for example as a sheet-shaped element of relatively stiff material, for example synthetic material, woven glass fibre or composite material, which can be bonded to the airbag 9' by means of for example glueing. Alternatively, the load-distributing element 17 can be provided by forming the front side of the airbag 9' in a more stiff manner than the rest of the airbag 9', for example by suitable weaving of the material in the airbag 9'. A third way of obtaining the stiffening of the load-distributing element 17 between the airbag 9' and the occupant is to weave in reinforcement material, for example in the form of threads of Kevlar or corresponding material, in selected parts of the web forming the airbag 9'. Consequently, the load-distributing element 17 can be said to form a part of the airbag 9', either in the form of an element which is fixed to the airbag 9' or in the form of a predetermined section of the airbag 9' which is designed so as to provide the load-distributing properties. Fig. 4 shows a perspective view of the embodiment according to Fig. 4, illustrating the position of the airbag 9' and the load-distributing element 17. Fig. 5 also illustrates in a schematical manner a gas generator 18 associated with the airbag 9'. In a known manner, the gas generator 18 can be used for inflating the airbag 9'. The position and dimensions of the airbag 9' and the load-distributing element 17 can be varied in accordance with the prevailing use and need not necessarily be the same as that shown in Figs. 4 and 5. However, the basic principle is that the load-distributing element 17 should distribute the load which is exerted by the legs of the occupant in the event of a collision. The front panel 16 of the lid 5' is preferably designed with rupture markings 19 (which are denoted by means of dash dotted lines in Fig. 5), i.e. weakened sections in the front panel 16. These rupture markings 19 are preferably designed in the form of the letter "H" and define an opening through which the airbag 9' can be inflated and expand when activated. Fig. 5 shows the device according to Figs. 3 and 4 in an active condition, i.e. a condition in which the airbag 9' is inflated. Fig. 6 also shows the legs 20 of an occupant. The drawing illustrates that the airbag 9' has assumed an inflated condition, wherein the front panel 16 of the glove compartment door 5' has been torn at the above-mentioned rupture markings to form two flaps 21, 22 between which the airbag 9' has been inflated. In accordance with what is stated above, the position of the load-distributing element 17 on the airbag 9' is adapted so that the point-shaped load arising as a consequence of the knees of the occupant 20 penetrating the airbag 9' can be absorbed and distributed along the surface of the airbag 9'. This in turn provides improved protection for the occupant 20. The airbags according to the above-mentioned embodiments can be provided with means for controlling the expansion thereof. For example, said means can be constituted by a tearable textile, i.e. a textile element which for example is sewn onto the base panel 15 (see Fig. 4) of the lid 5' and the front side of the airbag 9'. The tearable textile constitutes a resistance which controls the desired direction of the airbag. Alternatively, said means can be constituted by so-called trap bands which embrace the airbag at certain positions and which restrain it from further expansion above a certain limit. A third alternative are tearable seams, by means of which the airbag can be expanded in accordance with a desired progression. The invention is not limited to the above-mentioned embodiments shown in the drawings, but may be varied within the scope of the subsequent claims. For example, different materials can be used for the load-distributing element, i.e. the lid 5. Furthermore, the energy-absorption of the airbag 9 can also be affected by means of, for example, ventilation holes or by means of the gas flow and the permeability of the airbag 9. The device according to the invention, i.e. according to any one of the above-mentioned embodiments, can use an existing acceleration sensor which can be provided in the vehicle for use together with a conventional airbag for the upper torso. Alternatively, the invention can be assigned to a separate acceleration sensor. In the case where the vehicle is provided with several different airbag systems, it may also comprise a computer-based control unit which can be adapted for coordinating the timing during activation of the different airbags. Furthermore, the lid 13 can be designed in different ways, and can also be in the form of a curtain, for example of textile, which will be torn by the airbag during expansion thereof. The invention can also be arranged in connection with a sensor for detecting whether a passenger sits in the seat. In this manner, the airbag according to the invention can be arranged so as to be enabled to inflate only in the case where somebody is sitting in the seat.

Claims: Device for personal protection in vehicles, comprising an airbag (9; 9') which in its inactive condition is arranged in a space in connection with a dashboard (1) of the vehicle and in its active condition extends essentially in front of the legs and knees of an occupant in the vehicle, a sensor for detection of a condition generally corresponding to a collision, and means (10; 18) for inflating the airbag (9; 9') when the sensor detects that said condition prevails, characterized in that the device comprises a load-distributing element (17) which cooperates with the airbag (9; 9') in said active condition for distributing a load from the occupant (20), said load-distributing element (17) being constituted by a predetermined section of the airbag (9') which is designed with a stiffness which exceeds the stiffness of the remainder of the airbag (9'). Device according to claim 1, characterized in that the airbag (9) during inflation expands in a direction which is parallel to the dashboard (1) and extends essentially in the longitudinal direction of the vehicle. Device according to claim 1, characterized in that the airbag (9) is arranged in connection with an essentially closed space (4) in connection with the dashboard (1), the airbag being inflated inside said space (4) when activated. Device according to any one of the preceding claims, characterized in that the airbag (9), when activated, is adapted to be inflated through an elongated opening (12) which is arranged in the dashboard (1), essentially perpendicular to the longitudinal direction of the vehicle. Device according to claim 4, characterized in that it comprises a lid (13) which, in the inactive condition of the airbag (9), covers said opening (12) and is pivotable when acted upon by the airbag (9). Device according to any one of claims 1-5, characterized in that said load-distributing element (17) is constituted by a section of the airbag (9') which is woven in a manner so as to obtain said stiffness. Device according to claim 6, characterized in that said load-distributing element (17) is constituted by reinforcement fibres woven into the airbag (9'). Device according to any one of the preceding claims, characterized in that the airbag (9') is supported in a space in a lid (5') of an essentially closed space (4) in connection with the dashboard (1). Method for personal protection in a vehicle comprising an airbag (9; 9') which in its inactive condition is arranged in connection with a dashboard (1), comprising: detection by means of a sensor of a condition of the vehicle which generally corresponds to a collision, and activation of the airbag (9; 9') if said condition prevails, characterized in that the method comprises controlling said activation so that: the airbag (9; 9') is expanded to a position which is essentially directly in front of the legs and knees of an occupant (20) in the vehicle, and so that a load acting upon the airbag (9; 9') by said occupant is absorbed and distributed by means of a load-distributing element (17) which is arranged as a predetermined section of the airbag (9') which is designed with a stiffness which exceeds the stiffness of the remainder of the airbag (9'). Method according to claim 9, characterized in that the airbag (9') during activation is expanded from a space which is defined inside a lid (5') of said space (4) to a position in front of said passenger (20).

Inventors: SASLECOV VENTI, SASLECOV, VENTI
Applicants: VOLVO AB, AB VOLVO
Application year: 1996
Main classification: B60R21
IPC codes: B60R21