A safety device for a motor vehicle

Abstract: A safety device for a motor vehicle comprises an inflatable element which is initially stored in position in a recess in the door frame, but when inflated extends between the head of a person sitting in the motor vehicle and the door, or a window in the door. The device provides protection in a side impact or roll-over situation.

Description: THIS INVENTION relates to a safety device, and more particularly relates to a safety device in a motor vehicle such as a motor car. When a motor vehicle is involved in an accident there is a risk that the driver and passengers within the vehicle will be injured. It has been proposed to provide vehicles with safety devices to reduce the risk of such injury. Certain safety devices are intended to provide protection in the case of a side impact. US-A-5322322 discloses such a device. An inflatable tube is initially stored in a recess in the door frame above the door of the vehicle, and the ends of the tube are pivotally anchored to fixed points on the door frame. A sensor is provided to sense when an accident occurs, and to initiate inflation of the tube. As the tube inflates its length decreases, and it then extends linearly between the two fixed points on the door frame. The inflated tube provides some protection for the head of a person sitting in the vehicle. However, the tube is inflated to a substantial pressure, and thus the head of a person in the vehicle may tend to bounce off the tube. The tube may not cover the whole of the area of the window, and may not even cover the whole of the upper part of the window. There is thus a risk that the head of the person in the vehicle may move past the tube and pass through the window opening. If a car is rolling over this is very undesirable. DE-A-4134995 discloses a further arrangement in which an inflatable element is provided to provide protection for a person sitting in the vehicle. The disclosed arrangement includes an embodiment in which an inflatable element is provided which, when inflated, provides protection for a person sitting in a vehicle. The inflatable element has a linear upper edge portion which is secured to part of the vehicle located above the front door. The inflatable element includes a plurality of horizontal cells. The preamble of Claim 1 is based on this document This invention seeks to provide an improved safety device. According to this invention there is provided a safety device in a motor vehicle, the device comprising a gas generator, incorporating or associated with a sensor adapted to sense a side impact or a roll-over and to activate the gas generator, and an inflatable element connected to the gas generator to be inflated by gas from the gas generator, the inflatable element having an edge portion secured to part of the door frame of the vehicle, the inflatable element, when inflated, being positioned adjacent the door contained within the door frame, wherein the inflatable element is made of fabric comprising a first layer to define the front part of the inflatable element, and a second layer to define the back part of the inflatable element, selected parts of the first layer and second layer being interconnected to define points or lines where the front part and back part of the inflatable element are secured together, the inflatable element incorporating a plurality of substantially parallel elongate cells, wherein the said part of the door frame is non-linear, the inflatable element being mounted in a recess which extends from a point near the lower end of the A-post to a point on the C-post, the inflatable element thus having an edge portion secured to part of the door frame of the vehicle that extends over both the front and the rear door of the vehicle. The inflatable element, when inflated, is thus located between the head of a person sitting in the vehicle and an adjacent door. Usually such a door is provided with a window and so the inflated element provides protection from breaking glass from the window, and also prevents the head of the person in the vehicle from striking the window, or from being thrown out through the window, as can happen, particularly with roll-over accidents. Preferably the point on the C-post is near the lower end of the C-post Preferably the inflatable element made of interwoven fabric layers, the said selected parts of the first layer and the second layer being inter-woven. Preferably there is internal venting between the cells as this may reduce undesirable bounce that might occur if the cells were discrete and not vented to each other. The cells may be immediately adjacent each other or may be spaced apart Preferably the arrangement is such that as the cells inflate the length of the lower edge of the inflatable element is reduced. The fabric may have a single layer weight of less than 300g/m 2 . such as a weight of 175g/m 2 . Preferably when the inflatable element is inflated the pressure of gas is approximately 3 bar. In one embodiment the inflatable element is provided with a member mounted on the inflatable element adapted to move from an initial position to a further position on inflation of the inflatable element, a retaining arrangement being provided on the motor vehicle to retain the said member in the said further position. Thus a slider may be provided adapted to slide along a ratchet, and to be retained by the ratchet when it has moved to a further position. In order that the invention may be more readily understood and so that further features thereof may be appreciated the invention will now be described by way of example with reference to the accompanying drawings in which: FIGURE 1 is a side view of the interior of a motor vehicle provided with a safety device in accordance with the invention before the safety device moves to the operative state. FIGURE 2 illustrates the vehicle of Figure 1 when the safety device is in the operative state, FIGURE 3 is a sectional view of one form of safety device as shown in Figures 1 and 2, and FIGURE 4 is a sectional view of another form of safety device as shown in Figures 1 and 2. Figures 1 and 2 illustrate an embodiment of the invention intended to provide protection not only for a person in the front seat of a motor vehicle such as a motor car, but also for a person in the rear seat of the vehicle. Referring to Figure 1, a recess 40 is provided in the door frame 41 of a motor vehicle, the recess extending over both the front door 42 and the rear door 43. The recess extends from a point 44 located near the lower end of the A-post to a point 45 located near the lower end of the C-post. A channel 46 is provided on the B-post, extending vertically. In the channel 46 is a ratchet, and received within the upper end of the channel 46 is a ratchet engaging slide member 47. The slide member 47 is connected to a tab 48 which forms part of an inflatable element 49, which is initially stored within the recess 40. The inflatable element 49 is shown in the inflated state of Figure 2. The inflatable element has its top edge 50 secured to the part of the door frame 41 that extends above the doors 42, 43 of the motor vehicle. The top edge of the inflatable element is of non-linear configuration, and has a configuration which corresponds with the non-linear configuration of the upper part of the door frame. The inflatable element may be made of interwoven fabric. Such a fabric comprises a first layer that defines the front of the inflatable element - that is to say the part that is visible in Figure 2 - and a second layer that defines the back part - that is to say the part that is adjacent the window in Figure 1 - selected parts of the first region and second region being interwoven to define points or lines where the front part and the back part of the inflatable element are secured together. A technique for making an inflatable element of interwoven fabric is described in more detail in International Patent Publication WO90/09295. A gas generator 51 is provided which is connected to the inflatable element in such a way that when the gas generator is activated by a sensor that is formed integrally with the gas generator, or which is associated with the gas generator, and which responds to a side impact or to a roll-over situation to activate the gas generator, gas is initially supplied to the cells 52, 53, which are aligned with the tab 48. Thus initially, as the inflatable element 49 inflates, the cells 52 and 53 inflate and move the ratchet engaging slide member 47 downwardly. The ratchet engaging slide member 47 thus moves down the channel 46 to the position shown in Figure 2. The ratchet engaging slide member 47 engages the ratchet, and thus holds the tab 48 in its lower position. The rest of the cells 54 of the inflatable element are then inflated, and the inflatable element then extends fully across the upper parts of the windows in the doors 42, 43 of the motor vehicle. It can be seen that the lower edge of the inflated element 49 extends between the points 44 and 45 at the ends of the recess 40. As the inflatable element 49 inflates, so the length of the lower edge thereof decreases as a consequence of the inflation of the cells of the inflatable element. This reduction in the length of the lower edge, together with the action of the ratchet engaging slide member 47 ensures that the inflated element is retained in position as illustrated after it has been inflated. The lower edge of the inflated element decreases by about 10% between the un-inflated state and the inflated state. The inflated element is fully inflated within about 15ms. The total thickness of the inflated element, when inflated is approximately 30 - 40 mm. The seams of interweaving of the front part and the back part of the inflated element are approximately 30 -40 mm apart, so that the resultant cells are cylindrical when inflated. The total volume of gas within the inflated element may be between 7 and 9 litres, and the gas may be at a pressure of about 3 bar. While the inflated element is not provided with a vent to vent gas from within the element to the atmosphere, so that the inflated element, when inflated, remains inflated for a long period of time - to provide protection in the case of a protracted roll-over - there is venting between at least selected adjacent cells 52,53,54, to avoid any severe rebound. Thus if the head of the person in the vehicle impacts with the inflated element the pressure of gas within the whole element, or at least a substantial part of the element will rise, thus giving a "soft" impact. If each cell were sealed with no venting of this type, there would be a risk of severe rebound. The weight of the fabric should be kept to be as low as possible, so that if the inflatable element should impact with the head of the person in the vehicle as the inflatable element is inflated no harm will be done. It is thought that a material having a weight of less that 300 g/m 2 , such as 175 g/m 2 may be used. Figure 3 is a cross section showing the nature of the cells of the inflated element of Figures 1 and 2 . It can be seen that the cells are immediately adjacent to each other and are only separated by narrow regions where the fabric forming the front part of the inflated element has been woven with the fabric forming the back part of the inflated element. However, Figure 4 illustrates an alternative possibility, in which the regions of fabric between the cells that are woven together are relatively wide, the cells thus being separated by webs of fabric. The advantage of this latter possibility is that a smaller volume of gas may be required to fully inflate the inflatable member, meaning that the inflatable element may be inflated more rapidly. Whilst in the described embodiments of the invention inflatable element has been described as being made utilising a technique in which two layers of fabric are inter-woven to define points or lines where the front layer and the rear layer are inter-woven, it would be possible to form embodiments of the invention utilising two discrete layers of fabric which are interconnected by stitching.

Claims: A safety device in a motor vehicle, the device comprising a gas generator (51), incorporating or associated with a sensor adapted to sense a side impact or a roll-over and to activate the gas generator, and an inflatable element (49) connected to the gas generator to be inflated by gas from the gas generator, the inflatable element having an edge portion (50) secured to part of the door frame (41) of the vehicle, the inflatable element, when inflated, being positioned adjacent the door contained within the door frame, wherein the inflatable element is made of fabric comprising a first layer to define the front part of the inflatable element, and a second layer to define the back part of the inflatable element, selected parts of the first layer and second layer being interconnected to define points or lines where the front part and back part of the inflatable element are secured together, the inflatable element incorporating a plurality of substantially parallel elongate cells (52, 53, 54), characterised in that the said part of the door frame is non-linear, the inflatable element being mounted in a recess (40) which extends from a point (44) near the lower end of the A-post to a point (45) on the C-post, the inflatable element thus having an edge portion secured to part of the door frame of the vehicle that extends over both the front and the rear door of the vehicle. A safety device according to Claim 1 wherein the point (45) on the C-post is near the lower end of the C-post. A safety device according to Claim 1 or 2 wherein the inflatable element is made of inter-woven fabric layers, the said selected parts of the first layer and the second layer being inter-woven. A safety device according to Claim 3 where there is internal venting between the cells (52, 53, 54). A safety device according to any one of the preceding Claims wherein the cells (52, 53, 54) are immediately adjacent each other. A safety device according to the preceding claims wherein the cells (52, 53, 54) are spaced apart from each other. A safety device according to any one of the preceding claims wherein the arrangement is such that as the cells (52, 53, 54) inflate the length of the lower edge of the inflatable element is reduced. A safety device according to any one of the preceding claims wherein the inflatable element (49) is made of a fabric having a single layer weight of less than 300g/sq in. A safety device according to any one of the preceding Claims wherein when inflated, the pressure in the inflatable element (49) is approximately 3 bar. A safety device according to any one of the preceding claims wherein the inflatable element (49) is provided with a member (47) mounted on the inflatable element adapted to move from an initial position to a further position on inflation of the inflatable element, a retaining arrangement (46) being provided on the motor vehicle to retain the said member in the said further position.

Inventors: ANDERSSON STURE, FLORBERGER LARS-ERIK, HALAND YNGVE, SVENSSON I JORGEN, VALKENBURG SIMON, ANDERSSON, STURE, FLORBERGER, LARS-ERIK, HALAND, YNGVE, SVENSSON, I. JORGEN, VALKENBURG, SIMON
Applicants: AUTOLIV DEV, AUTOLIV DEVELOPMENT AB
Application year: 1996
Main classification: B60R21
IPC codes: B60R21, B60R22