GAS GENERATOR WITH THROTTLE ELEMENT

Abstract

Gas generator (1) with a device (2) for supplying a pressurized gas, a gas outlet section with a line (3), a throttle element (4) arranged in the gas outlet section, wherein the throttle element (4) has several openings (17, 18) for the passage of the gas and is made of a material that is deformable by a gas flowing through the throttle element (4) when the pressure of the gas is above a predetermined pressure, wherein the throttle element (4) is deformable from a first position in which gas can flow through the several openings (17, 18) of the throttle element (4) to at least a second position in which a gas flow (G) through at least a part of the several openings (17, 18) is prevented or reduced, wherein in one of the first and second positions at least a part of the throttle element (4) has a concave shape;wherein at least one of the openings (17) is arranged centrally to the throttling element (4); preferably the central opening (17) has a circular cross-section; ; further comprising a stop shoulder (9) for the deformed throttle element (4), wherein the stop shoulder (9) is arranged in the line (3) of the gas generator (1) downstream of the throttle element (4) with respect to the direction of the gas flow (G) and wherein a gas flow (G) through a part of the openings (17, 18) is prevented or reduced by the stop shoulder (9) when the throttle element (4) has been deformed; wherein the stop shoulder (9) is a disk (19) provided with gas passages (20, 26), the disk being arranged downstream of the throttling element (4) with respect to the direction of gas flow (G) and being spaced a distance (H; L) from the throttling element (4) such that it can be touched by the throttling element (4) when the throttling element (4) is deformed; and wherein the disk (19) has a closed / filled central area (21) and the central area of ​​the throttling element (4), which has the central opening (17), can come into contact with the central area (21) of the disk (19), thereby blocking the gas flow through the central opening (17) of the throttling element (4).

Description

AREA OF INVENTION

[0001] The present invention relates to a gas generator with a throttle valve. The invention relates in particular to a gas generator with a throttle valve that is an inflator for an airbag, capable of generating a high-pressure gas flow in a very short time, and in which the gas flow must be reduced, for example, during the first 15-40 milliseconds of generation. Examples of gas generators include inflation devices in vehicle restraint systems, such as airbags, especially curtain airbags, and inflation devices for inflatable seat belts. BACKGROUND OF THE INVENTION

[0002] Airbag inflators must release large quantities of gas in a very short time (often just a few milliseconds) to inflate an airbag after a vehicle impact is detected. Airbag inflators are commonly referred to as cold gas inflators and hybrid inflators. A cold gas inflator contains compressed gas that is released from a reservoir by a pyrotechnic device. Hybrid inflators (or hybrid gas inflators) also contain compressed gas in a reservoir and, in addition, a quantity of propellant that heats the compressed gas as it leaves the reservoir. The pressure of the gas generated by the inflator, particularly in pressurized gas inflators and hybrid inflators, is sensitive to ambient conditions, especially temperature.

[0003] Pressure profile curves and gas flow curves change with temperature, so pressure profiles and gas flow rates at cold temperatures (i.e., at approximately -35°C) and down to ambient temperature (i.e., up to approximately 23°C) differ from profiles and rates at higher temperatures (i.e., up to 90°C). As a result, an airbag can inflate faster if the inflation device has been stored at a high temperature than if it has been stored at a low temperature.

[0004] Several proposals were made to address the problem of changes in the performance of an airbag inflator at different gas temperatures. It was suggested that valves be used to vent some of the gas to the atmosphere, or rotary or slide valves, as described in US 5,489,117 A or US 5,743,558 A. Other solutions included a shape-memory alloy element (US 6,655,712 B1) that reduces the fluid flow area at high temperatures, and a variable throttle element for the gas flow from the inflator.

[0005] The latter solution is disclosed in US 2007 0138 775 A1; it provides a throttle element having at least one tab inclined toward the inflation device to allow gas flow from the inflation device to the airbag through a first flow region. When the gas pressure reaches a predetermined value, the tab is bent into the remaining part of the throttle element to reduce the passage available in the throttle element for gas flow from the inflation device. The use of a throttle element with a variable passage for gas flow from the inflation device results in a pressure profile of the hot stored gases that more closely matches the pressure profile at ambient temperature.

[0006] Similar solutions are disclosed in WO 2010 058 251 A1 and DE 195 26 547 A1, which provide a throttling element that deforms according to the gas pressure and thereby reduces or prevents the flow through openings to the inflation device. DE 20 2004 019 448 U1 discloses a similar solution for the discharge opening of a gas bag module of an airbag.

[0007] The problem with the solutions discussed above is that they use special materials and / or require a complex structure. This, in turn, can lead to inconsistent performance and potential malfunction of the throttling elements or valves used in the inflation device.

[0008] The aim of the present invention is to solve the aforementioned problems and to create an inflation device with a variable gas flow throttle that serves as a valve for controlling the pressure profiles of gas at different temperatures in a range of, for example, -35°C to +90°C. The throttle valve should be easy to manufacture, economical, structurally simple, and highly reliable in operation.

[0009] The throttle valve flap should also be free of tabs. As discussed above with reference to US 2007 0138 775 A1, tabs or similar elements must bend during operation at high temperatures to reduce the flow area for the gas, while the remaining part of the throttle element retains its original flat shape. In the present invention, the entire throttle element is deformed to some degree, with the deformation typically being greater in the central part of the throttle element. SUMMARY OF THE INVENTION

[0010] The above objective is achieved by the present invention, which relates to a gas generator according to claim 1. Specifically, the invention provides a gas generator with a throttle valve, wherein the throttle valve is arranged in an output line of the gas generator, the throttle valve comprising a throttle element and a housing for a portion of the throttle element, the throttle element having at least one opening, preferably a central opening. Generally, the throttle element is a sheet made of a metal material. The throttle element is deformable by the action of the pressurized gas flow.Depending on the gas flow pressure, the throttling element can be deformed from a first position, in which gas can flow through the (central) opening of the element, to a second position, in which at least part of the (central) opening is blocked by an adjacent inflation structure, preventing or at least reducing the gas flow through the opening. As mentioned above, the gas pressure is sensitive to ambient conditions, and especially to temperature.

[0011] The invention thus provides a gas generator comprising a novel deformable throttling element having at least one opening, which can be deformed by the pressure of the gas flowing through the outlet line of the inflation device into a position in which part of the one or more openings is at least partially blocked in order to reduce the flow rate of the gas through the deformed throttling element and thus control the pressure downstream of the throttling element (with respect to the direction of gas flow). The throttling element can, for example, be at least partially blocked by an adjacent stop element. In one embodiment, the throttling element is plastically deformable; in another embodiment, the throttling element is flexible. In one embodiment, the throttling element can have a central opening and further openings near the edge of the throttling element.Since the deformable throttling element can bend, the amount of gas flow passing through the throttling element can be reduced, as one or more of the openings, preferably the edge openings, are either directly or indirectly, partially or completely blocked, e.g. by their deformation and / or by at least one adjacent stop element of the gas generator structure.

[0012] In one embodiment, the gas generator is an inflator, particularly for an airbag; in the following description, reference is made to a gas generator that is an inflator for an airbag, but this should not be understood as limiting the device, which includes a throttling element as shown, to an inflator for an airbag. The throttling element can be part of a throttle valve. DESCRIPTION OF THE INVENTION

[0013] The throttling element of the invention offers several advantages over the prior art. Specifically, the throttling element enables the reduction of the gas pressure ramp in the airbag cushion during "hot" temperature deployment and the minimization of the difference compared to the ramp steepness at ambient or cold temperatures. This is intended to reduce the stress on the cushion and other components of the airbag module involved in deployment, thus enabling a more robust and cost-effective product design. The same benefits could be applied to other vehicle components affected by module deployment, such as trim panels and grab handles for the curtain airbag. Furthermore, depending on the design concept, the throttling element can be readily used with cold gas inflators and hybrid inflators, and it would also be possible to use it with pyrotechnic devices specifically designed for this application.

[0014] The variable gas flow gas flow throttling element or valve comprises at least one opening, preferably more than two openings, i.e., passages for a gas flow coming from the gas generator. In one embodiment, the throttling element has a centrally arranged opening and two or more additional openings arranged laterally, i.e., peripherally. In the present invention, the throttling element is made of a material that can deform under the pressure P of the gas exiting the gas generator when the pressure P is higher than a certain value. Generally, the throttling element does not deform when the gas pressure is the gas pressure in the inflation device at a cold temperature, and may deform slightly when the gas pressure is the pressure when the inflation device is at room temperature; this deformation does not change the performance of the inflation device.

[0015] When the gas is under a pressure higher than the gas pressure in the inflation device at cold or ambient temperature, and the inflation device is activated, pressurized gas at a pressure P or higher flows out of the inflation device's pressure vessel and deforms the throttle element under the driving force of the pressurized gas. If the pressure is sufficiently high, the throttle element is deformed to such an extent that it comes into contact with a stop element of the adjacent inflation device, and the gas flow through at least one of the throttle element's openings is reduced or stopped, i.e., prevented.

[0016] In an unclaimed embodiment, there is a central opening that is always open and at least one further opening, which may be a plurality of peripheral, i.e., directly or indirectly closed, side openings. The number of peripheral openings is preferably two, but more preferably four side openings are provided in the throttling element. At least some of the peripheral openings are blocked or obstructed when the throttling element is deformed into its second position, so that the gas flow through these openings is stopped or reduced. In another embodiment, the central opening is wholly or partially blocked, while the peripheral openings remain free and provide the necessary passages for the pressurized gas flow.In another embodiment, there is no stop element; the at least one opening is deformed together with the throttling element to reduce the inlet area and thus the gas flow through the opening or openings.

[0017] The shape of the openings of the throttling element is not limited, and the same throttling element can have differently shaped openings. For example, these openings can include geometric shapes consisting of curved (circular arcs) and straight line segments. Specifically, the following geometric shapes are illustrated here: circle, oval, rectangle, ellipse, crescent, stadium, etc. These geometric shapes can include both regular and irregular shapes, with circular shapes being preferred. Regardless of the shape of the peripheral openings, in a throttling element, the total area of ​​the passages that is free to allow gas flow is preferably larger than the total area of ​​the passages through which the gas flow is stopped or blocked. Thus, the ratio between the opening area that remains open even when the throttling element is deformed (e.g.,the area of ​​the central opening), and the total area of ​​the openings that are blocked when the throttling element is deformed (e.g. the peripheral or lateral openings), 1.0 or higher; preferably this ratio is in the range of 35 / 65 to 45 / 55, preferably 40 / 60 to 45 / 55.

[0018] The throttling element for the variable gas flow can be in the form of a disk with any geometric shape, preferably a circular disk. It can be made from a plate of a material that is resistant to the high temperatures (e.g., it does not melt) of the gas from the inflation device and that can deform under the gas flow at a pressure above a predetermined value; as mentioned, the deformation can increase with the increase in the pressure of the inflation gas. According to embodiments of the invention, the throttling element deforms plastically and remains in this state after use. Examples of such a material are: a metallic material, such as a steel alloy, e.g., FePO2, stainless steel, nickel alloys, such as nickel-chromium alloys, e.g., those sold under the brand name INCONEL®, and nickel-copper alloys, e.g., those sold under the brand name MONEL®.

[0019] The throttling element of the inflation device of the present invention can have a thickness between 0.5 and 4 mm, depending on the material used and the maximum gas pressure. In particular, the thickness of the throttling element depends on the internal pressure used in the pressure vessel of the inflation device and on the mechanical properties of the material used to prepare the throttling element. For the aforementioned metallic materials, the thickness is preferably in the range of 1.5 to 3.0 mm, most preferably 1.85 to 2.5 mm.

[0020] The outlet section of the inflation device of the invention can include a conduit; the outlet section or conduit section comprises a support element for interacting with the deformed throttle element and a housing (e.g., a stop shoulder or a step in the wall of the outlet section) to receive the throttle element such that at least the circumferential edge of the downstream surface of the variable gas flow throttle element is supported in the housing (e.g., a stop shoulder), while the downstream surface of the throttle element is spaced apart from the support element of the outlet conduit section. As already mentioned, in one embodiment, the throttle element is normally (before deformation) flat, e.g., it is a part made of a sheet metal; the edge or periphery of the throttle element is supported by a housing located in the outlet conduit of the inflation device, i.e.,The structure of the inflation device provides a suitable housing; a suitable housing is a stop shoulder or a step provided in the wall of the outlet pipe section, i.e., on the inner surface of the outlet pipe wall. The throttle element is capable of deforming from a first position, in which the throttle element is flat and gas from the inflation device can flow through the central and peripheral openings of the throttle element, to a second position, in which the throttle element has been deformed by the gas, usually plastically. In the second position, the downstream surface of the throttle element (i.e., the surface downstream with respect to the gas flow) is in contact with, or very close to, a stop element; in this state, at least a portion of the central or lateral openings is substantially blocked, directly or indirectly, and the gas flow through them is prevented, i.e., stopped or reduced.The deformation of the throttle element can vary depending on the pressure P of the gas flow, which is temperature-dependent. Thus, different gas temperatures can result in different deformations of the throttle element, with the deformation increasing with temperature. Deformation can begin at or just above ambient temperature.

[0021] The stop element is located downstream of the throttle element; it can be, for example, a step or similar section that protrudes from or is incorporated into the structure of the inflation device's outlet section. Another suitable stop element can be a disc with wide openings, i.e., openings that allow the unimpeded passage of gas supplied by the inflation device to the airbag cushion. The solid parts of the stop disc provide a stop for one or more of the throttle openings, usually the centrally located one.In particular, the throttling element deforms under the driving force of the pressurized gas exiting the pressure vessel of the inflation device in the direction of the stop shoulder of the inflation device's outlet line, whereby a circumferential region of the downstream surface of the throttling element comes close to or into contact with the stop shoulder, thus obstructing or blocking the gas flow through the lateral openings. If the stop element is the disk discussed above and the throttling element is deformed by the pressurized gas, the downstream surface of the throttling element comes close to or into contact with the disk body; in particular, the disk body can block the central opening of the throttling element.

[0022] In the first position, i.e., an undeformed position, the downstream face of the throttle element is separated from the upstream face of the outlet line's stop element by a predetermined distance. This distance is typically in the range of 0.8 to 3.8 mm, preferably 1.0 to 3.0 mm; this distance applies to both the stop shoulder and the disc stop. Preferably, the central opening and other openings of the throttle element have a predetermined diameter depending on this distance.

[0023] In the case of operation at high temperatures, such as 80-90°C, the gas pressure in the inflation device's pressure vessel is so high that it can deform the throttle element in such a way that the throttle element contacts the lower stop shoulder, thereby minimizing or blocking the gas flow through the side openings. Therefore, in this case, the pressurized gas during airbag deployment can only flow through the central opening of the throttle element, with such a constriction reducing the total gas flow mass exiting the gas generator's pressure vessel and entering the airbag. As can be seen from the following drawings, a portion of the throttle element, typically its outer edge or circumference, remains essentially enclosed within its housing. The remaining portion of the deformed throttle element, i.e.,The part of the throttle element that is not located in the housing (or stop shoulder) of the outlet pipe is moved towards the stop element or another part of the structure of the inflation device to block the peripheral or central openings by bringing part of the deformed part of the throttle element into contact with the stop shoulder of the stop element or another stop element of the structure of the inflation device.

[0024] In an unclaimed embodiment of the Fig. In the gas generators shown in Figures 1-3b, the stop element is part of the structure of the inflation device, namely a stop shoulder or step that is touched (or substantially touched) by the part of the throttle element that, in the deformed state of the throttle element, is free of openings (i.e., gas passages). In this embodiment, see Figure 1-3b. Fig. 3a and Fig. 3b, the peripheral openings are not directly blocked, but the gas flow through them is restricted and stopped in order to achieve a closure of the openings located on the circumference of the throttling element.

[0025] In another possible embodiment, the stop element, as already mentioned, is a disc located transversely in the outlet line downstream of the throttling element with respect to the gas flow in the inflation device. This disc is preferably made of a hard or semi-hard material, i.e., a material that does not deform under the operating conditions of the inflation device and partially obstructs the gas flow from the inflation device. The disc according to this embodiment has a cross-section with cavities (openings) around a closed / filled central area, the central axis of which corresponds to that of the central opening of the throttling element.

[0026] The stop element can have a three-dimensional shape, wherein the closed or filled central region can project from the plane of the stop element, provided that the shape of the central region of the stop element is capable of at least partially blocking or impeding the gas flow through the central opening of the throttle element, while allowing the gas flow through the side openings of the throttle element. Some illustrative, but not limiting, examples of the three-dimensional shape of the abutment according to the present invention are shown in the Fig. Figures 7(a)-7(i) illustrate this. Accordingly, the stop element has a three-dimensional shape and includes cavities (openings) on its surface as well as a closed or filled central area that projects towards the central opening of the throttle element. The shape of such a stop element can be conical, curved (or domed), or combinations thereof with differently shaped, projecting central areas, as shown in the Fig. 7(a)-7(i) are shown.

[0027] During operation, when the inflation device is activated, the throttle element deforms under the driving force of the pressurized gas. Normally, the deformed throttle element has a concave shape relative to the direction of gas flow; that is, a concavity is present on the upstream side of the throttle element. The degree of deformation of the throttle element can vary depending on the pressure P of the gas flow, which in turn also depends on the temperature (e.g., increasing concavity). Thus, different deformations can occur at different gas temperatures, with the deformation increasing with the temperature.In a fully deformed state, the central area of ​​the throttle element, which has a central opening, contacts the central area of ​​the stop element located in the outlet line of the inflation device downstream of said throttle element, thereby reducing or blocking the gas flow through the central opening of the throttle element. Consequently, the gas from the pressure vessel of the inflation device can only flow through the cavities (openings) of the stop element and the lateral openings of the throttle element. Thus, the flow velocity of the pressurized gas exiting the inflation device is reduced if the pressure of the gas inside the vessel is high enough to deform the throttle element.

[0028] The term “hard or semi-hard material” in connection with this invention refers to a material that is essentially non-deformable under the gas pressure and gas flow acting on its surface, while the term “closed or filled” refers to an area without cavities or openings.

[0029] The invention also offers the advantage that the following parameters of the throttle element and the mounting element of the inflation device can be designed and adapted to achieve fine-tuning of the throttle valve's performance: material of the throttle element, thickness of the throttle element, diameter of the central opening of the throttle element, number and diameter of the lateral openings of the throttle element, distance of the throttle element to the lower stop shoulder or stop disc, and diameter and shape of the stop shoulder or disc.

[0030] Selecting these variable parameters, depending on the desired effect, allows for determining the pressure gradient within the airbag cushion and minimizing performance differences between high and ambient temperatures of the pressurized gas. Furthermore, these variable parameters enable finding the optimal compromise for the throttle valve, minimizing its influence at low and ambient temperatures while ensuring a consistent deceleration of gas flow from the inflation device's pressure vessel at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The invention will now be described in a non-restrictive manner with reference to the accompanying drawings, in which: Fig. Figure 1 is a perspective view of a pressurised gas inflation device (inflator) according to the invention. Fig. Figure 2 is a cross-sectional view of some possible embodiments of the throttle element according to the invention. The Fig. 3A and Fig. Figure 3B are enlarged fragmentary longitudinal sections before and after the deformation of a throttling element in a section of the output line of the inflation device according to a possible embodiment which is not claimed. The Fig. 4A and Fig. Figure 4B shows diagrams of hot, cold and ambient pressure-time curves recorded with an inflation device with a standard gas flow throttle according to the prior art, compared to the same inflation device with a throttle element of the present invention; Fig. Figure 5A shows a cross-sectional view of another embodiment of the inflation device according to the present invention; Fig. Figure 5B shows a schematic top view of the throttle element of Fig. 5A; and Fig. Figure 6 is a schematic representation of the inflation device of the present invention as part of a vehicle restraint system in combination with a curtain airbag; The Fig. 7A, Fig. 7B and Fig. Figures 7C are enlarged, fragmentary longitudinal sections of a section of the outlet line of an inflation device according to another possible embodiment of the present invention; The Fig. 8A, Fig. 8B and Fig. Figures 8C are enlarged fragmentary longitudinal sections of a section of the outlet line of an inflation device according to another possible embodiment of the present invention; The Fig. 9A, Fig. 9B and Fig. Figures 9C are enlarged fragmentary longitudinal sections of a section of the outlet line of an inflation device according to another possible embodiment of the present invention; The Fig. are schematic, fragmentary longitudinal section views of a section of the outlet pipe of an inflation device according to another possible embodiment, which is not claimed; The Fig. 11A and Fig. Figure 11B are schematic, fragmentary longitudinal sections of a section of the outlet line of the inflation device according to another possible embodiment, which is not claimed. DETAILED DESCRIPTION OF THE INVENTION

[0032] Fig. Figure 1 shows an inflation device 1 according to the present invention for inflating an airbag. With reference to Fig. 1 and Fig. 3A, Fig. 3B comprises the inflation device 1, a means for supplying a pressurized gas, which in this embodiment is a vessel 2 for storing pressurized gas; the inflation device further comprises an outlet pipe 3, a circular throttling element 4 with a central opening 17 and four peripheral or lateral openings 18, a locking element 5 for blocking the outlet of the pressurized gas from the vessel 2, an inflation head 6, and a release mechanism 7. The throttling element 4 is located upstream of the locking element 5 with respect to the gas flow G, and its circumferential edge 4a is mounted in a housing 8, which is located in the wall of the outlet pipe 3, i.e., on the inner surface of the wall 3a, as shown in Fig. 3 shown, is provided. A preferred housing for the edge 4a of the throttling element 4 is generally a shoulder (or step) 3b provided on the inside of the wall 3a.

[0033] When the inflation device is actuated by a signal sent from an impact sensor 25 to the triggering mechanism 7, the triggering mechanism 7 displaces or breaks open the locking element 5, thereby opening the interior of the container 2 so that the pressurized gas can escape from the container 2 into the airbag 22. An inflation device 1 according to the present invention is in Fig. Figure 6 shows the inflation device 1 as part of a vehicle restraint system, wherein the inflation device 1 is connected to a curtain airbag 22, which is attached to the vehicle by means of a clamp 23. In particular, the gas outlet line 3 of the inflation device 1 is connected to the curtain airbag 22, i.e., to an inflatable volume of the curtain airbag 22, by means of a filling tube 24.

[0034] Fig. Figure 2 shows some possible embodiments for the shapes, positions, and distribution of the openings in the throttling element 4 of the variable gas flow throttle. Accordingly, the openings can have different dimensions and regular and irregular geometric shapes, including circular, oblong, elliptical, stadium, and crescent shapes. Regardless of the shape of the peripheral and central openings, the ratio between the opening area that remains open even when the throttling element is deformed (e.g., the area of ​​the central opening) and the total area of ​​the openings that are blocked, i.e., through which the gas flow is stopped when the throttling element is deformed (e.g., the peripheral – lateral openings), is in the range of 35 / 65 to 45 / 55, preferably 40 / 60 to 45 / 55.

[0035] After the in Fig. In the embodiment shown in Figure 3, which is not claimed, the flow rate of the compressed gas exiting the container 2 through the openings of the throttling element 4 is controlled by the plastic deformation of this throttling element 4, i.e., by closing or partially blocking the flow through the lateral openings by bringing the throttling element 4 into contact with the surface of the lower stop shoulder 9, which serves as a contact element in the outlet line 3, as shown in Figure 3. Fig. 3B is shown.

[0036] The deformation of the throttling element 4 is a function of the pressure of the gas coming from the container 2. To achieve suitable deformation of the throttling element 4 in the outlet line 3 at contact with the lower stop shoulder 9 (i.e., the contact element), it is therefore advantageous to select the material and thickness of the throttling element 4 appropriately in relation to the distance between the upper surface of the throttling element 4 and the surface of the lower stop shoulder 9. The throttling element of the inflation device of the present invention can have a thickness between 0.5 and 4 mm. In particular, the thickness of the throttling element 4 depends on the internal pressure in the pressure vessel 2 of the inflation device 1 and on the mechanical properties of the material used to prepare the throttling element 4. Examples of such a material are: a metallic material, such as a steel alloy, e.g.FePO2, stainless steel, nickel alloy, nickel-chromium alloys sold under the brand name INCONEL®, and nickel-copper alloys sold under the brand name MONEL®. The thickness for the above-mentioned metal materials is preferably in the range of 0.5 to 4.0 mm, more preferably 1.5 to 2.5 mm, and most preferably 1.85 to 2.0 mm. For these materials and thicknesses, a suitable distance between the top surface 10 of the throttle element 4 and the stop shoulder 9 is in the range of 1.0 to 4.0 mm.

[0037] With regard to the Fig. 3A and Fig. 3B and its enlarged cross-section of the outlet line 3 of the inflation device 1, the throttle element 4 is provided in a housing 8 of the outlet line 3. The housing of the throttle element is a shoulder 3b located on the inner surface of the wall 3a upstream of the stop shoulder 9 and the locking element 5. The upper, i.e., downstream, surface 4b of the throttle element 4 is arranged at a distance H from the upstream (with respect to the gas flow direction G) surface of the lower stop shoulder 9 such that deformation of the throttle element 4 in the direction of the surface of the stop shoulder 9 is possible. This distance H should be large enough that, during deformation of the throttle element 4, the surface 4b of the throttle element 4 contacts the surface of the lower stop shoulder 9 when the gas pressure reaches a predetermined value.In this way, the flow through the lateral openings 18 of the throttling element is at least partially blocked or reduced, resulting in a smaller quantity of pressurized gas exiting the pressure vessel 2 of the inflation device 1. In other words, the gas flow through the passages 17, 18 is reduced by deformation of the throttling element 4. This effect of generating a reduced gas flow through the inflation device of the present invention is more significant in the case of gas stored at high temperatures, such as temperatures in the range of 60°C to 90°C, where the pressure of the gas is higher than that of gas stored at ambient temperature or of cold gas, and consequently, the deformation of the throttling element is more significant.

[0038] Another possible embodiment of the present invention is described in the Fig. 5A and Fig. Figure 5B shows a flat disk 19 used as a stop element in the outlet line 3 of the inflation device 1. The disk 19 is fixed and transversely arranged in the outlet line 3 of the inflation device 1 downstream of the throttling element 4 at a distance L such that a central area of ​​the throttling element 4 contacts the disk 19 when the throttling element 4 is completely deformed by the driving force of the pressurized gas exiting the inflation device 1. The distance L between the upstream surface of the disk 19 and the downstream surface of the throttling element 4 can be between 1.0 and 4.0 mm, relative to the flow of the pressurized gas exiting the inflation device.The disk 19 is made of a hard or semi-hard material, and the surface of the openings 20 is such that the gas can flow through them without the flow rate being significantly reduced compared to the flow through the throttling element 4.

[0039] A plan view of disk 19 is shown in Fig. Figure 5B shows that the disk 19 is flat and has a cross shape with four large cavities (openings) 20, which have substantially equal areas around a closed / filled central area 21 and within a circular circumferential element 27. The closed / filled central area 21 of the disk 19 has a central axis that corresponds to the axis of the central opening 17 of the throttle element 4. The disk 19 is located (see Figure 5B). Fig. at a distance L from the throttling element 4 such that the central region of the throttling element 4 comes into contact with the closed / filled central region 21 of the disk 19 when the throttling element 4 is completely deformed by the driving force of the pressurized gas exiting the inflation device. When the inflation device 1 is activated and a selected pressure is reached, the throttling element 4 deforms under the driving force of the pressurized gas. During deformation, the central region of the throttling element, which has a central opening 17, can come into contact with the closed central region 21 of the disk 19, which is located in the outlet line 3 of the inflation device 1 downstream of the throttling element 4, thereby blocking the gas flow through the central opening 17 of the throttling element 4, while allowing the gas flow through the lateral openings 18 of the throttling element 4.

[0040] Due to the presence of four cavities (openings) 20 in the disc 19 and the fact that the lateral openings 18 of the throttling element 4 are not blocked, there is a free passage through the openings 20 of the disc 19 for the pressurized gas escaping from the container 2 of the inflation device. The disc 19 provides at least partial blockage of the central opening 18 of the throttling element 4.

[0041] As a further variation in the shape of the stop element, i.e. the disc 19, which is in the Fig. 5A and Fig. As shown in Figure 5B, the stop element can also have a three-dimensional shape. In particular, this three-dimensional stop element 29 is shown in the Fig. 7-9 shown.

[0042] The in the Fig. 7A, Fig. 7B and Fig. The stop element shown in Figure 7C has a substantially convex or conical shape with a vertex upstream of the gas flow. The stop element 29 can cooperate with the throttle element 4, which deforms under the driving force of the gas exiting the inflation device 1. Fig. Figure 7A shows the stop element 29 and the throttle element 4 in a non-operational state of the inflation device 1, wherein the apex 29a of the conically shaped stop element 29 is spaced apart from the flat throttle element 4. The stop element 29 has a closed / filled central area and lateral openings 26.

[0043] The Fig. 7B and Fig. Figure 7C shows the effect of the driving force of the gas exiting the inflation device 1, i.e., a deformation of the throttle element 4 in the direction of the stop element 29. As already mentioned, the deformation of the throttle element and the formation of a concavity in the throttle element can occur to varying degrees depending on the pressure P of the gas flow, which is temperature-dependent. Fig. Figure 7B shows the deformation that occurs when the pressure is so high that the throttling element 4 is only partially deformed; in this second position, the throttling element is deformed into a concave shape, with respect to the direction of the gas, such that the central opening 17 of the throttling element 4 is closed or blocked by the narrowing around the apex of the conically shaped stop element 29, while the pressurized gas can flow through the lateral openings 18 of the throttling element 4 and the lateral openings 26 of the stop element 29.

[0044] The in the Fig. 8A, Fig. 8B and Fig. The stop element 29 shown in Figure 8C has a curved or domed shape and consists of a closed / filled central area and lateral openings 26; the same parts of the device are identified by identical reference numbers. The operation of the device is identical to the operation of the device of Fig. 7A-7C.

[0045] The in the Fig. 9A, Fig. 9B and Fig. The stop element 29 shown in Figure 9C has a conical shape with a protruding and rounded apex 29a, which is closed or filled. This protruding apex is shaped so that it can engage in and possibly penetrate the central opening 17 of the throttle element 4 when the throttle element 4 is deformed under the driving force of the gas exiting the inflation device 1, as shown in Figure 9C. Fig. 9B and Fig. Figure 9C illustrates this. This particular three-dimensional shape of the stop element 29 allows the central opening 17 of the throttle element 4 to be partially or substantially completely closed, while still allowing the passage of the pressurized gas flow through the lateral openings 18 of the throttle element 4 and the lateral openings 26 of the stop element 29 of the throttle valve. The lateral openings 18 of the throttle element 4 are not blocked or closed by the stop element 29. The function of the device is essentially identical to the function of the device of the Fig. 7A-7C.

[0046] According to another possible embodiment, which is not claimed and which is in the Fig. 10A and Fig. As shown in Figure 10B, the throttle element 4 has only one opening 17, which is centrally located and has an initial diameter “a”. Fig. Figure 10A shows the throttle element 4 before the activation of the inflation device, while Fig. Figure 10B shows the deformed and concave throttle element 4 after activation of the inflation device, with a gas pressure high enough to completely deform the throttle element against the stop shoulder 9. The gas inlet area of ​​the opening 17 changes with the deformation of the throttle element to an opening with diameter “b”, which is smaller than the initial diameter “a”. The gas flow rate through “b” is lower than through “a”, thus achieving the pressure control effect downstream of the throttle valve of the invention. As in the previously disclosed embodiments, the degree of deformation of the throttle element can depend on the gas pressure P.

[0047] The in the Fig. 11A and Fig. The throttle element shown in Figure 11B, which is not claimed, differs from the one in the Fig. 10A and Fig. 10B by the fact that the side of the throttling element 4 which faces in the direction opposite to the gas flow G from the pressure vessel has a reinforced area 40 around its central opening 17, wherein the material of the throttling element 4 has a greater thickness with respect to the thickness of the adjacent areas of the throttling element. The said reinforced area 40 forms a projection around the said central opening 17. Fig. Figure 11A shows the throttle element 4 before the activation of the inflation device, while Fig. Figure 11B shows the deformed throttle element after activation of the inflation device.

[0048] In both in the Fig. 10 and Fig. In the embodiments shown in Figure 11, the throttle valve operates in the same way. In particular, the Fig. 10A and Fig. Figure 11A shows the throttle element in an unloaded state when the inflation device 1 is in a non-operational state, so that no force is exerted on the surface of the throttle element. When the inflation device is activated, the pressurized gas flow G pushes the flexible or deformable throttle element 4 towards a stop element 39, causing the throttle element 4 to deform and the stop element 39 to break, thus allowing the gas G to escape from the inflation device 1, as shown in the Fig. 10B and Fig. Figure 11B shows that during the deformation of the throttle element 4 under the driving force of the gas G, the central opening 17 also deforms such that a partial reduction of the central opening to the diameter “b” is achieved, i.e., the diameter “b” of the central opening 17 after deformation is smaller than the diameter “a” before activation of the inflation device, i.e., b <a. Die Verformung der zentralen Öffnung ist viel deutlicher, wenn um die zentrale Öffnung 17 im Drosselelement ein verstärkter Bereich 40, d.h. ein Bereich mit erhöhter Dicke, vorhanden ist, wie in Fig. 11A and Fig. 11B is shown. In both in the Fig. 10 and Fig. In the embodiments shown in Figure 11, the deformation of the central opening 17 of the deformed throttle element 4 causes a reduction in the gas flow through this opening, wherein this reduction is a function of the thickness of the material of the throttle element or the thickness of the reinforced area around the opening of the throttle element.

[0049] The in Fig. The diagrams shown in Figure 4 are the result of comparative tests conducted with an inflation device according to the prior art and with the same inflation device but with a throttling element according to the present invention. The inflation device according to the prior art has a line 3 without a throttle, while the inflation device according to the invention has a throttle which, in its undeformed state, offers the same flow resistance as the line 3 of the inflation device according to the prior art. The total free area in the throttle available for gas passage is the same in both channels. The stop element of the inflation device 1 was a stop shoulder 9, which was positioned in the outlet line 3 according to the diagrams shown in Figure 4. Fig. The embodiment shown in Figures 3A-3B was provided for. The throttle element used in the comparative tests was steel C30 HV10 130-135 and was cut from a steel sheet 1.85 mm thick; the throttle element had one central opening and four peripheral openings with a ratio of central opening area to peripheral opening area of ​​39 / 61. The distance (h) between the downstream face of the throttle element 10 and the stop shoulder 9 was 1.2 mm. The pressure profiles obtained from the comparative tests are shown in the diagrams of the Fig. 4a and Fig. 4b shown.

[0050] The diagrams of Fig. 4A and Fig. Figure 4B shows the gas pressure curve in the outlet line downstream of the throttle as a function of time during the deployment of a pressurized airbag stored at a high temperature (85°C), ambient temperature (25°C), and a low temperature (-35°C). The gas pressure in the reservoir was 737 bar at 85°C, 613 bar at 25°C, and 495 bar at -35°C.

[0051] The dashed lines 11, 12, 13 refer to the pressures measured at various time intervals using the known standard inflation device at a hot temperature (line 11), at room temperature (line 12), and at a cold temperature (line 13). The solid lines 14, 15, 16 refer to the pressures measured at various time intervals with an inflation device of the present invention at a hot temperature (85°C, line 14), at room temperature (line 15, 25°C), and at a cold temperature (line 16, -35°C). The solid lines 14, 15, 16 of the diagram of Fig. Figures 4a show the pressure measured at various time intervals using the inflation device of the invention disclosed above, wherein the throttle element 4 has a central opening 17 with a diameter of 3.5 mm and a distance H of 1.2 mm between the downstream surface 4b of the throttle element and the surface of the stop shoulder 9 in the outlet line 3. The ratio of the area of ​​the central opening to the area of ​​the peripheral openings was 39 / 61. The solid line 14, which shows the trend of the gas pressure as a function of time at a high temperature (+85°C), clearly demonstrates improved performance of the inflation device, i.e., a significantly lower outlet pressure, compared to the known standard inflation device represented by the dotted line 11, in which the gas exits the inflation device into the airbag at a higher pressure.

[0052] It is noteworthy that the performance of the inflation device of the present invention at 85°C is essentially equivalent to the initial performance (in the first 10-20 ms) of the same inflation device at 25°C, as well as that of the known standard inflation device at 25°C, i.e., at room temperature. Consequently, the inflation device of this invention minimizes the difference in ramp rate at high temperature compared to the ramp rate at ambient temperature, i.e., at 25°C. This means that in the initial phase of airbag deployment, i.e., until approximately 20 ms after activation of the inflation device, the hot gas enters the airbag at a similar flow velocity to that achievable by pressurized gas at ambient pressure.The pressure-time curves of this diagram show the improved performance of the inflation device of the present invention compared to the known standard inflation device in the case of gas stored at a high temperature in the container of the inflation device.

[0053] The diagram of the table in Fig. 4b was created under the same conditions as in the Fig. The comparative test shown in Figure 4a was used, with the difference that the inflation device of the present invention had a throttle element in which the central opening 17 had a diameter of 3.6 mm and a distance H of 1.0 mm between the downstream surface of the throttle element 10 and the surface of the lower stop shoulder in the outlet line 3. The ratio of the area of ​​the central opening to the area of ​​the peripheral openings was 45 / 55. In this comparative test, the inflation device of the present invention achieved better performance compared to the known standard inflation device.The solid line 14, which shows the trend of the gas pressure at a hot temperature (85°C), indicates that the inflation device of the present invention in this configuration can achieve a hot gas initial pressure that is much lower than that achievable with the known standard inflation device, as registered by the dotted line 11.

[0054] Since the initial phase of airbag deployment, which occurs up to approximately 20 milliseconds after activation of the inflation device, is crucial for preventing potential damage to the airbag or the vehicle's body panels during use, hot deployment is carried out using a reduced-pressure ramp, as shown by continuous line 14 in Fig. in relation to hot inflation with the known standard inflation device, as shown by the dashed line 11.

[0055] The table charts in Fig. 4a and Fig. The comparative test results shown in Figure 4b demonstrate that the inflation device of the present invention has a significantly better performance compared to the known standard inflation device in the case of gas stored at high temperature, i.e. at high pressure, while still exhibiting good performance at room temperature and at cold temperature. Reference sign 1 inflation device 2 containers 3 Exit line 3a Wall 3b Shoulder 4 Throttle element 4a Circumferential edge 4b Surface 5 Locking element 6 inflatable heads 7. Trigger mechanism 8 cases 9. Shoulder stop 10 Top side of the throttle element 11, 12, 13 dashed line 14, 15, 16 solid line 17 (central) opening 18 (side) opening 19 discs 20 openings 21 (closed / filled) central area 22 (curtain) airbag 23 terminal 24 Filling tube 25 Impact sensor 26 side openings 27 circular circumferential element 29 Stop element 29a Vertex 39 Stop element 40 (reinforced) area G Gas flow H, L distance

Claims

[1] Gas generator (1) with a device (2) for supplying a pressurized gas, a gas outlet section with a line (3), a throttle element (4) arranged in the gas outlet section, wherein the throttle element (4) has several openings (17, 18) for the passage of the gas and is made of a material which is deformable by a gas flowing through the throttle element (4) when the pressure of the gas is above a predetermined pressure, wherein the throttle element (4) is deformable from a first position in which gas can flow through the several openings (17, 18) of the throttle element (4) to at least a second position in which a gas flow (G) through at least a part of the several openings (17, 18) is prevented or reduced, wherein in one of the first and second positions at least a part of the throttle element (4) has a concave shape;wherein at least one of the openings (17) is arranged centrally to the throttling element (4); preferably the central opening (17) has a circular cross-section; further comprising a stop shoulder (9) for the deformed throttle element (4), wherein the stop shoulder (9) is arranged in the line (3) of the gas generator (1) downstream of the throttle element (4) with respect to the direction of the gas flow (G) and wherein a gas flow (G) through a part of the openings (17, 18) is prevented or reduced by the stop shoulder (9) when the throttle element (4) has been deformed; wherein the stop shoulder (9) is a disk (19) provided with gas passages (20, 26), the disk being arranged downstream of the throttling element (4) with respect to the direction of gas flow (G) and being spaced a distance (H; L) from the throttling element (4) such that it can be touched by the throttling element (4) when the throttling element (4) is deformed; and wherein the disk (19) has a closed / filled central area (21) and the central area of ​​the throttling element (4), which has the central opening (17), can come into contact with the central area (21) of the disk (19), thereby blocking the gas flow through the central opening (17) of the throttling element (4). [2] Gas generator (1) according to claim 1, wherein the gas outlet section comprises a line (3) with a housing (8) for the throttling element (4), wherein the housing (8) supports the throttling element (4) along its circumferential edge (4a). [3] Gas generator (1) according to claim 2, wherein the housing (8) is a shoulder or step (3b) provided on the inside of the wall (3a) of the conduit (3). [4] Inflation device for an airbag comprising a gas generator (1) with a throttle element (4) according to any preceding claim. [5] Inflation device according to claim 4, wherein the inflation device is selected from a cold inflation device and a hybrid inflation device. [6] Airbag arrangement with an inflation device according to claim 4 or 5. [7] Airbag arrangement according to claim 6, wherein the airbag is a curtain airbag (22).

Images