DE2339610A1 - SAFETY DEVICE FOR THE OCCUPANCY OF A VEHICLE - Google Patents

Description

^D a! Ent% iwältu Dipl.-Ing. W. Scherrmann Dr.-Ing. R. Roger

7300 Esslingen (Neckar), Fabrikstrasse 24, PO Box 348

August 3, 1973 _{Τβ | βίοη}

PA 87 SChO Stuttgart (0711) 356539

359619

• Telegrams patent protection Esslingenneckar

Eaton Corporation 100 Erieview Plaza Cleveland, Ohio 44114 / üSA Safety holding device for occupants of a vehicle

The invention relates to a safety holding device for occupants of a vehicle with a collapsed, restrained ineffective state in a vehicle occupant when a vehicle impact occurs State of expandable structure, for example in the form of a gas bag or cushion, to which a medium source is assigned which has a pressure vessel filled with pressure medium, which is connected to the gaseous pressure medium the gas guiding device admitting the structure is connected via a normally closed outlet channel, which can be opened when the vehicle impact occurs.

Such a safety holding device is described, for example, in US Pat. No. 3,516,685 and US Pat. No. 3,602,527,

The expandable structure, which is usually also referred to as an air bag or air cushion, can be folded up State on a steering wheel, a dashboard or at another location within the motor vehicle essentially be attached in front of the normal seating position of a vehicle occupant. As well as the occurrence of an impact of the vehicle is detected, the expansion of the

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Formed generally by means of a medium source in Causes the shape of a pressure vessel, which has a single pressure chamber in the gas under a pressure of example

2
about 253 kg / cm is stored. The stored gas is released from this single pressure chamber in that part of the pressure vessel which is connected to the gas guide device, usually a diffuser connected to the structure, is torn open. The gas flows into the structure through the gas guide device. The size, ie the passage area of the channel through which the gas exits, depends on certain features, v / ie the desired expansion time, the total gas volume of the expanded structure and the medium source, as well as on the pressure of the gas stored in the medium source and the desired pressure in the expanded structure. In most cases, the expansion of the structure is completed within 100 milliseconds of the detection of the occurrence of a vehicle impact, in order to effectively restrain a vehicle occupant.

The clear passage cross-sectional area of the outlet channel of the medium source is generally fixed, while the outlet channel itself is closed by a rupture disc. Upon detecting the occurrence of a A collision of the vehicle is triggered by an electrical signal emitted by an impact sensor Explosive charge ignited, which ruptures the rupture disc and the stored gas with full force the expansion of the structure can begin. The rapid expansion of the structure caused by the flowing in from a single pressure chamber Gas is caused is inherently useful for effective restraint of a vehicle occupant. the causes rapid increase in the mass flow per unit of time of the gas flowing from the single pressure chamber however, unnecessarily large stresses on the structure and

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a large shock pulse that acts on the structure immediately after the rupture disc ruptures. One Reduction of the stress on the structure and this shock impulse would be for the structure itself, its production costs, as well as appropriate for the functioning of the facility.

The invention is therefore based on the object of a safety holding device To create the types mentioned above, in which the stress on the expandable structure and the impact impulse coming into effect during the

Expansion of the structure are reduced.

The safety holding device is used to solve this problem according to the invention, characterized in that the pressure vessel is set up to receive two pressure medium Has chambers, of which a first chamber is connected to the outlet channel and both of which have a passage opening are in connection with each other, the smallest clear 'passage cross-section of the passage opening being smaller is the smallest clear passage cross-section of the outlet channel.

In the case of the new safety holding device, the expansion takes place of the expandable structure with variable speed, but the expansion is so occurs in good time that an occupant of the vehicle is effectively protected when an impact occurs.

According to a further feature, the new safety holding device characterized in that the volume of the first chamber is smaller than the volume of the second chamber.

Further advantageous features and properties emerge from the following description of one in the drawing

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illustrated embodiment of the subject matter of
Invention, as well as from the subsequent subclaims.

In the drawing show:

1 shows a section from a motor vehicle with a safety holding device according to the invention in perspective representation,

FIG. 2 shows the safety holding device according to FIG. 1 cut along the line 2-2 of FIG. 1 in one
Side view and in the cutout and

Fig. 3 is a diagram to illustrate the time

Dependence of the mass flow per unit of time of the gas flowing into the structure, if present leakage outflow from the structure, in the case of a known one single-chamber medium source and, in the case of the medium source, the safety holding device according to FIG. 2.

1 and 2, together with a motor vehicle 12, a safety holding device IO for vehicle occupants is shown, which is designed similar to that which is described in US Pat. No. 3,602,527. The holding device has an expandable structure 14, for example an airbag or an air cushion, which is fastened to a dashboard 18 under an appropriate padding 16. With in that
Formation 14 is a medium supply source 20, which contains gas such as air or nitrogen under pressure, via a
elongated diffuser tube 22 per se of known construction in connection, which has a gas guide channel 24 which is formed with a number of slots 26 which open into the structure 14.

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The medium supply source 20 has, as in particular from 2 shows a cylindrical pressure vessel 28 which has an opening 30 provided with an internal thread; a valve 32 is screwed with an external thread part into the internal thread of the opening 30; it has an in a ceramic plug 36 arranged explosive charge 34. The plug 36 seals a cylindrical outlet channel 38 which is arranged centrally in the valve 32. Between the plug 36 and the interior of the pressure vessel 28 is a rupture disk 40 is provided which additionally seals the outlet channel 38. The outlet channel 38 is after Rupture of the rupture disk 40 and the removal of the plug 28 and gas duct 24. The explosive charge 34 is over electrical lines 42 electrically connected to a (not shown) sensor. A suitable probe is described, for example, in U.S. Patent 3,414,292.

Although different types of valves can be used, the valve shown is but advantageously a so-called explosion valve in which the rapid opening of the outlet channel 38 by tearing the rupture disc 40 and removing the plug 36 a rapid exit of the stored gas from the pressure vessel 28 is permitted. The valve 32 is in its details in U.S. Patent 3,567,245.

The interior of the pressure vessel 28 is by a circular partition 48 which is rigidly connected to the pressure vessel _/ into a primary chamber 44 and with a secondary chamber 46th The primary chamber 44 preferably has a smaller volume than the secondary chamber 46. The partition wall 48 is welded at 49 to front and rear cylindrical sections 28a, 28b of the pressure vessel 28. Other constructive solutions are quite possible. A cylindrical, calibrated passage opening is centrally located in the partition wall 4 8

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arranged, which is with the chambers 44, 46 in communication. The minimum cross-sectional area of the passage opening 50 is smaller than the smallest cross-sectional area of the outlet channel 38.

A valve 52, which is known per se and which leads into the chamber 46 and is used for this purpose, is attached to the pressure vessel 28 Pressure vessel 28 after the outlet channel 38 has been closed by the rupture disc 40 and the plug 36, a gas, such as

Air or nitrogen at a pressure of about 253.1 kg / cm

to fill in.
Operating mode

During normal vehicle operation, the structure 14 is in a collapsed inoperative state on the dashboard 18. As well as the motor vehicle 12 hits another object with such great force that the sensor is triggered, an electrical signal is supplied via the electrical lines 42, which the Explosive charge 34 ignites. The resulting explosion causes rupture disk 40 to rupture and be removed of the plug 36, so that the outlet channel 38 between the primary chamber 44 and the gas duct 24 of the diffuser 22 is opened. After opening the outlet channel 38 begins in the Primary chamber 44 contained gas immediately with the expansion of the structure 14, whereby the padding 16 is torn. With the gas outlet from the primary chamber 44 after the opening of the outlet channel 38, gas flows from the secondary chamber 46 through the passage opening 50 into the primary chamber 44. Since the cross-sectional area of the outlet channel 38 is greater than the cross-sectional area the passage opening 50, the gas exits the primary chamber 44 faster than it exits through that in the secondary chamber 46 contained gas can be replaced. The different outflows from the primary chamber 44 and the chamber 46 results in a relatively rapid expansion of the structure

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over a short period of time during the evacuation of the primary chamber 44 and then a subsequent, more gradual one Expansion of the structure during the emptying of the secondary chamber 46. As the cross-sectional area of the outlet channel 38 is significantly larger than the cross-sectional area of the passage opening 50, the duration and size of the will be proportionate rapid expansion period of the structure 14 initially by the amount of gas contained in the primary chamber 44 and the light The cross-sectional area of the outlet channel 38 is determined during the duration and size of the relatively gradual expansion period first by the cross-sectional area of the passage opening 50 and the amount of the in the secondary chamber 46 contained gas are given.

By appropriate choice of the cross-sectional areas of the outlet channel 33 and the passage opening 50, as well as the amount of gas contained in each chamber, the structure of that in the Primary chamber 44 contained gas initially inflated so far that it is released for further expansion and a vehicle occupant who is not properly seated in the vehicle seat at a regulated speed is moved back. Subsequently, the structure 14 is continuously different from that contained in the secondary chamber 46 Gas filled more slowly until the completion of the expansion of the structure within the desired period of time to thereby to hold one or more of the vehicle occupants and to prevent that this vehicle occupant or these vehicle occupants come into contact with the windshield 54 of the motor vehicle. The possibility of an optionally controllable medium outflow from a pressure vessel 28, means a considerable departure from the known single-chamber Gas storage facilities. In addition, the maximum outflow velocity of the gas from the pressure vessel is determined 28 reduced, whereby the stress and the momentum of the structure 14 are reduced.

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Constructive basics

In the following, an explanation is given in a general manner / which is intended to make it easier for those skilled in the art to identify the source of the printing medium according to Fig. 2 and the advantages that it has in compared to a single-chamber pressure medium supply to see. In this analysis, assumptions are made that are not necessarily of practical use Safety restraint device for vehicle occupants, according to the invention, apply. It is assumed, however, that these assumptions do not materially affect an understanding of the invention as described and claimed. Of the For the sake of simplicity, isentropic and adiabatic state conditions are assumed for the analysis.

Let us first consider a known storage gas supply source, in which there is no partition 48 and therefore the pressure vessel 28 only has one chamber, with It is also assumed that no gas blows off from the structure 14 through blow-out spots or the like, as they do normally found in such holding devices for motor vehicles (see for example US-PS 3,573,885). The following applies under these conditions:

1) M ₁ Ct) = M ₁ Ct ₀ ) - Hi ₁ t

Here, t is the point in time immediately before the explosive charge 34 is triggered; t is any point in time after t M (t) is the mass of the gas contained in the chamber of the pressure vessel 28 at the point in time t; Μ _χ (t _Q ) is the mass of the gas contained in the chamber of the pressure vessel 28 at time t _Q; Finally, Hi ₁ is the mean mass outflow velocity of the gas through the outlet 38 from the point in time t to the point in time t.

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In addition, the following applies:

2) M _c (t) = M _c (t _o ) + In ₁ 1

Herein M (t) is the mass of the at the time t in the Formation 14 contained gas, while M (t) is the mass of the gas contained in the formation 14 at the time t.

The following also applies:

3) m.t = f (P. - OJ

JL A. C *

Here, P. is the gas pressure in the chamber of the pressure vessel 28; P is the gas pressure in the structure 14 and f is denoted in FIG of equation (3), as well as "a function of" throughout the consideration; it means no special function. That Gas flows from the high pressure source to the low pressure source. Initially, P. is much larger than P. From the foregoing it follows that:

4) M _c (t) = M _c (t _o ) + f (P ₁ - P _c >

If there are no leak openings in the structure 14.

In the event that gas from the structure 14 through blowout spots of the structure and assuming that the mean leakage mass flow velocity m between the times t, t let:

5) M _L (t) - m _L t = f (P _c - P _A >

Where P is the atmospheric pressure and MrCt) is the gas mass, which emerged from the structure 14 at the time t. Taking into account the

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leakage gas that has entered equation (4):

6) M _o (t) = M _c (t _o ) + f (P ₁ - P _c ) - f <P _C - P _A )

In the following it is assumed that the pressure vessel 28 is designed according to FIG. 2, the previously mentioned Chamber of the single-chamber medium supply storage source is now divided into two chambers 44, 46 by the partition 48 and the clear cross-sectional area of the outlet channel 38 is greater than the clear cross-sectional area of the passage opening 50 is. Without gas leakage from the structure 14, the following applies:

7) M ₄₄ (t) = M ₄₄ (t _o ) - m ₄₄ + m ₄₆ t

Herein M ₄₄ (t) is the mass of gas contained in chamber 44 at time t; M ₄₄ (t) is the mass of gas in chamber 44 at time t; ₄₄ is the average mass flow rate of the gas exiting through the outlet passage 38 between times t and t; Μ._ Finally, the average mass is 4b

flow velocity of the between the times t and t of gas flowing through the passage opening 50. In addition, if there is no leakage gas from the structure:

8) M _c (t) = M _c (t _o ) + m ₄₄ t

According to equation (2). Similar to equation (3), the following applies:

9) ^ 44 ^t = ^{f (P} 44 ~ V

Where P _{44 is} the pressure of the gas contained in chamber 44,

In the event that the structure 14 has a leakage outflow per unit of time corresponding to m _{L # which is caused by Aus} _

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is due to bubble stains or the like, applies to the two-chamber medium source:

10) M _c (t) = M _c (t _o ) + f (P ₄₄ - P _c ) - f (P _c - P _A )

According to equation (6), with the difference that f (P44 ~ ^p ) with the two-chamber medium source increases more slowly than f (P ₁ - P) with the single-chamber medium source as a function of time, because P ₄₄ decreases faster than Pm. If the leakage flow, ie f (P - P) in the structure filled from the single-chamber or the two-chamber medium supply source, is the same, the gas volume and the gas pressure in the single-chamber and the two-chamber medium source are the same, the outlet channels 38 are identical and the passage opening is smaller than the outlet channel 38, the maximum amount of gas in the structure that is filled from the single-chamber medium source is greater than the maximum amount of gas in the structure filled by the two-chamber medium source. In addition, the time is the time to remove the gas from the two-chamber medium source required is greater than the time required to remove the gas from the single-chamber medium source.

With or without leakage gas outlet from the structure 14, there is a time t _ß at the two-chamber medium source. P ₄₄ = P. If t is less than t _E , a gas flow from the pressure vessel 23 through the outlet channel 38 is controlled, while if t is greater than t ", the gas flow from the pressure vessel 28 through the calibrated passage opening 50 is regulated. At the first moment of the flow, m ^

approximately the same size as In ₄₄ , so that an almost identical first impulse for the expansion of the structure 14 results. There

M ,, but smaller than M, is takes m. with closer to t ^ heran-44 1 44. L

moving t no longer as fast as m, too. With increasing Time increases the influence of the passage opening 50 to up to

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Time t = t ", nu, the remaining expansion of the structure certainly. Because the clear cross-sectional area of the passage opening 50 is smaller than the clear cross-sectional opening of the outlet channel 38, m ,, is smaller than m ...

In the case of a device with a leakage gas outlet from the structure, it is assumed that the volume of the single-chamber and the two-chamber medium source, as well as the corresponding structure is the same that the same leakage gas outlet from the structure is present and that the gas pressure and the outlet channel 38 in the single-chamber and the two-chamber Medium source is the same. Then it follows from the previous consideration that the Meissen outflow pro Time unit from a new zv / eikamnerigen medium source has a smaller maximum value compared to that from a single-chamber medium source, but when approaching from t to t, - has a higher final value, where t- means the point in time at which the structure 14 is complete is widened. These circumstances are illustrated in the diagram of FIG. 3.

It is assumed that the total volume of the single-chamber and the two-chamber medium source is the same that the clear cross-sectional area of the outlet channel 3 8 according to FIG Fig. 2 is the same size as the clear cross-sectional area of the outlet channel of the single-chamber medium source and that the gas pressure in both medium sources is the same. Then results in an increase in the volume of the chamber 44 or a reduction in the ratio of the cross-sectional area of the outlet channel 38 to the cross-sectional area of the Passage opening 50 an increase in the maximum mass flow per unit of time in the two-chamber medium source until the volume of the chamber 46 to zero or that The cross-section ratio will be equal to or less than one,

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at which point in time the medium source according to FIG. 2 then in the same way as a single-chamber medium source acts and the two curves of FIG. 3 correspond to one another.

An increase in the maximum gas mass flow per unit of time results in an increase in the stress on the structure 14 and in the shock pulse emanating from it. An increase in the volume of the chamber 44 or an increase in the passage ratio of the outlet channel 38 to the passage opening 50 results in a reduction in the maximum mass outflow per unit of time from the two-chamber medium source, as well as an increase in the time required to fill the structure 14. While both of these conditions are desirable from a stress and shock pulse point of view ₇ their effectiveness is ultimately limited by the fact that the structure 14 must be fully expanded in less than 100 milliseconds from the time the crash condition occurs to ensure effective restraint of a vehicle occupant. By changing the passage area of the outlet channel 38 and the passage opening 50 , the volume of the chamber 44 and 46, and the pressure of the gas stored in the pressure vessel 28, a medium supply source can be created which corresponds to the desired conditions in a structure 14 of known volume.

Assuming that the total volume, gas pressure and the outlet channels of the single-chamber and the two-chamber Medium source are the same, the two-chamber medium source needs a longer time to fill a structure 14 with a given volume and a given leakage gas outflow. In order to fill the structure 14 from the two-chamber medium source to shorten the time required, a number of can be attached to the holding device

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Changes are made. For example, the leakage outflow from the structure can be reduced, the total volume and or the pressure of the two-chamber medium source is increased and or the volume of the structure can be reduced.

Since the flow of the major part of the gas flowing into the structure 14 is more likely through the passage opening 50 than is controlled by the larger outlet channel 38 and since the size and shape of the passage opening 50 is constant remain, the shape of the mass flow curve will be at the new two-chamber riediumsquelle more reliable from unit reproduced to a unit than with a single-chamber medium source when changing the dimension in which the outlet channel the pressure vessel is opened by the explosive charge and or changes in the shape of the explosive charge opening generated the repeatability of the special Can adversely affect mass flow curve.

For an outlet channel 38 with a tearable closure, more than two chambers connected one behind the other can also be provided be. With a three-chamber medium source, the 3rd chamber may be larger or smaller than the chambers 44,46. The clear cross-sectional area of the through opening between the 3rd chamber and the chamber 46 would have to be smaller than the clear cross-sectional area of the passage opening 50, which in turn is always smaller than the clear passage area of the outlet channel 38.

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Claims (5)

P a t e η t claims Iy safety restraint device for occupants of a vehicle, having a collapsed, ineffective state in a vehicle occupant upon entering a Vehicle impact restrained state expandable structure, for example in the form of a gas bag or -kissens to which a medium source is assigned that a with Comprises pressure vessel filled with pressure media, which is provided with a gas-conducting device which admitted the gaseous pressure medium into the structure is connected via a normally closed outlet duct, which when the vehicle impact occurs can be opened suddenly, characterized in that the pressure vessel (28) has two for receiving from Has pressure medium set up chambers (4.4,46) of which a first chamber (44) is connected to the outlet channel (38) and - both of which have a passage opening (50) are connected to each other and that the smallest clear passage cross section of the passage opening (50) is smaller as the smallest clear passage cross section of the outlet channel (38). 2. Safety holding device according to claim 1, characterized in that the pressure vessel (28) has a pressure chamber which is divided into the two chambers (44, 46) by a partition (48) and that the passage opening (50) is arranged in the partition (48). 3. Safety holding device according to claim 1, characterized in that the volume of the first chamber (44) is smaller than the volume of the second chamber (46). 4. Safety holding device according to one of the preceding claims, characterized in that in the first and in the second chamber (44,46) as a pressure medium gas under a 409808/0463 - 16 - Pressure and stored in an amount that is necessary for full Expansion of the structure (14) are sufficient. 5. Sicherheitshaiteeinrichtung according to one of the preceding Claims, characterized in that the passage opening (50) has a predetermined, unchangeable, fixed passage cross-sectional area and has shape. 409808/0463