EP1503134A1

EP1503134A1 - Method and device for filling a container with pressurised gas and for closing and sealing same immediately thereafter

Info

Publication number: EP1503134A1
Application number: EP02730306A
Authority: EP
Inventors: Luis Lopez Alonso; Noelia Moreno Alvarez; Marco Antonio Carrascosa Perez
Original assignee: Dalphi Metal Espana SA
Current assignee: Dalphi Metal Espana SA
Priority date: 2002-05-06
Filing date: 2002-05-06
Publication date: 2005-02-02
Also published as: AU2002302653A1; WO2003093721A1

Abstract

The procedure according to the invention comprises a first stage of filling the container with pressurised gas, a second stage of blocking the gas inlet duct by means of the forceful of driving the into and clinching of a metal ball in the said duct and a third stage of sealing the gas inlet duct by means of a circumferential weld which closes the container at the zone external to the ball.

The device according to the invention includes means for coupling in a gas-tight manner to the container, including a positioning element with lips destined to produce a groove in the base of the container, means to carry out the filling with pressurised gas and means to close the gas inlet duct with a metal ball including a piston capable of forcefully driving the ball into the interior of the duct and deforming its lower part in the form of a plane surface.

Description

FIELD OF THE INVENTION

The present invention relates to a procedure and a device for filling a container with pressurised gas and for closing and sealing it immediately afterwards. Such containers have a multitude of applications, there being among them that of the inflation of airbags used in automobile vehicles.
More particularly, this invention refers to a procedure in which a metal ball is used as a blocking element of the gas in the inlet duct and a device to carry out both the filling of the container with gas, and blocking of its gas inlet duct.

BACKGROUND OF THE INVENTION

EP 889279 A2 describes an apparatus and a procedure for filling a container with pressurised gas and for closing the same with an object similar to that of the present invention.
The apparatus has an adapter for the container which creates a gas-tight chamber to facilitate filling with gas and a conventional filling device. In addition, the apparatus includes a device to effect the closure by means of a metal ball which is allowed to fall under gravity and which is welded to the extremity of the inlet duct.
In the apparatus and procedure object of EP 889279 A2 the ball used for the closure is positioned by a rod which is also an electrode of a system for incandescent welding, condenser discharge or similar.
The necessary incorporation of a welding system of this type within the apparatus is a disadvantage as it implies the requirement for maintenance tasks on the welding system.
A further disadvantage is that great precision is required in the zone of contact of the ball with the inlet duct of the container to correctly carry out the welding.
A further disadvantage is its limitation to containers filled with inert gases because, otherwise, there would be risk of ignition or explosion because, due to the energy transferred and the impurities existing in the contact surfaces, the welding system would produce sputtering and the projection of metallic and non-metallic substances at high temperatures.
A further disadvantage is that by not introducing the whole of the ball into the gas inlet duct there exists a risk of rupture of the weld caused by any fall or impact which the gas container may suffer.
In addition, some solutions are known in the art for closing a gas container subsequent to being charged with a pressurised gas which use, particularly, a metal ball to block the duct used to fill the container with gas, such as those which are briefly mentioned below.
JP 11280982 describes a mechanical solution which combines the introduction of a metal ball into the gas inlet of the container with the deformation of the periphery of the inlet mouth of the said duct as a means to ensure the closure.
EP 0947745 A1 describes diverse solutions which employ a mechanical element situated in the inlet duct to the container and an element welded to the container on the external side of the mechanical element. In some embodiments of the invention the mechanical element and the welded element are a single element; in other embodiments they are different elements. In this latter case, the use is mentioned of a metal ball as a mechanical element and of a male element as an element welded to the container.
DE 19902 940 A1 describes a solution using a metal ball which is introduced under pressure into the first part of the inlet duct to the gas generator which has a diameter equal to or somewhat greater than a second part of the duct. The ball is introduced into the duct to a sufficient depth to leave a sealing surface.
These solutions for the closure of containers filled with pressurised gas may efficiently fulfil their function, but they only cover one of the operations object of the present invention: the closure of the container.

SUMMARY OF THE INVENTION

The present invention has as its object to provide a procedure and a device for filling and closing a gas generator which resolves the disadvantages stated in respect of EP 889279 A2.
For this purpose, the procedure of filling a container with pressurised gas and of closing the gas inlet duct to the said container according to the invention includes, as in the case of EP 889279 A2, a stage of filling with the gas provided by a rapid filling system (boiler, pump ......) and a stage of blocking the said duct with a metal ball. However, this blocking stage is not carried out by welding the ball to the duct but by forcefully driving it into it and deforming it.
In addition, the procedure according to the invention includes a third stage of sealing by means of a circumferential weld which closes the container at the zone external to the ball. Thus, this sealing is not carried out to join the ball to the container, but to seal the container, which is closed by the ball. Due to this closure, the gas is unable to escape and this permits making a weld by following a standard procedure such as, for example, by arc.
Thus, in the procedure of the present invention, the closure of the gas inlet duct is carried out by means of a first mechanical operation of forcefully driving the ball into the duct and a second operation of welding to seal the duct.
The device according to the invention permits the efficient realisation of the two first stages, of filling with gas and of blocking the gas inlet duct. The third stage, of sealing the closure, is realised once the container has been separated from the filling and sealing device, using conventional arc welding machines.
The filling and closure device includes means of coupling in a gas-tight manner to the container and filling it with the gas provided by the filling system and means to effect the closure of the said duct with a metal ball comprising a piston capable of forcefully driving the ball into the duct and deforming its lower part to form a plane surface, by means of which the container remains closed and ready for a subsequent sealing operation.
The said means of coupling may include a positioning element with lips for the purpose of positioning and producing grooves in the container to impede the escape of the gas to the exterior during the filling of the container with pressurised gas.
The said grooves are produced by means of a compression force which maintains in position the element to be filled and counteracts the pressure which is generated in filling the chamber.
An advantage of the separation of the blocking stage from the sealing stage in the procedure object of the present invention and the use of the device mentioned, solely for the blocking stage, is its applicability to the filling of containers with any gas, differing from that which occurs in EP 889279 where, given the risk of explosion, the scope of application is restricted to inert gases.
A further advantage of the present invention is the robustness of the closure, both due to the location of the ball within the gas inlet duct and the deforming of its lower part and the safety provided by the sealing stage.
Other characteristics and advantages of the present invention may be gathered from the detailed description which follows an illustrative embodiment, in no sense limitative, of its object in relation to the drawings enclosed.

DESCRIPTION OF THE FIGURES

Figure 1 is a cross-section view of the lower part of a gas container with the gas inlet duct.
Figure 2 is a cross-section view which shows the coupling between the lower part of the container and element of the filling and closure device and the forces which are exerted over the same prior to proceeding to the filling.
Figure 3 is a cross-section view which shows, in the filling stage, the filling and closure device according to the invention coupled to the gas container.
Figure 4 is a cross-section view which shows, in the blocking phase, the filling and closure device according to the invention coupled to the gas container.
Figure 5 is a cross-section view which shows, in the final phase of the blocking stage, the filling and closure device according to the invention coupled to the gas container.
Figures 6 and 7 are, respectively, perspective and cross-section views of the gas container subsequent to its separation from the filling and closure device, once the blocking stage has been completed.
Figure 8 is a cross-section view which shows the sealing of the container using an arc welding device.
Figures 9 and 10 are, respectively, perspective and cross-section views of the gas container subsequent to the stage of sealing, by means of arc welding.

DETAILED DESCRIPTION OF THE INVENTION

Following Figures 1 and 3 a container 16 may be observed which is filled with a pressurised gas through the inlet duct 17 situated in its lower part and immediately afterwards is closed, by means of the filling and closure device 1, coupled to the same.
The filling and closure device 1 comprises the following elements:

A securing element 2 of the container 16 by its lower part with a ring 3 to facilitate its introduction and extraction subsequent to completing its filling and closure. The ring 3 fits in a gas-tight manner to the container 16 both when it is empty and when it is full.
A securing element 14 of the container 16 by its upper part with a ring 15 to facilitate the introduction and extraction of the container 16.
A positioning element 4 of the filling and closure device which includes lips 6 destined to create a groove 6' in the container 16 and an orifice 5 which permits the connection to atmospheric pressure of the chamber 13 created between the container 16, the securing element 2, the ring 3 and the positioning element 4.
A supporting element 7 of the securing element 2, the ring 3 and the positioning element 4 which includes in its interior a housing for a gas filling system 10 and a duct 8 to permit the passage of gas to inlet duct 17 of the container 16 and a housing for a mechanical device responsible for carrying out the closure of the container comprising a piston 11 and a steel ball 12, housed in a duct 9 along which they are able to travel.

As may be observed in Figure 3, the chamber 13, delimited by the container 16, the securing element 2, the ring 3 and the positioning element 4, will receive any possible loss of gas which occurs during filling.
The orifice 5 of the positioning element 4 is responsible for the chamber 13 being communicated with the exterior to prevent an increase in pressure in the same due to a possible failure in the coupling or closure between the group container 16 and the positioning element 4.
On being coupled to the container 16, the filling and closure device 1 creates in it the groove 6' whose characteristics depend, as shown in Figure 2, on the forces F and F1.
Figure 3 also illustrates the first stage of the procedure of filling and the container 16 with the pressurised gas in which it may be observed that the gas supplied by the filling system 10 exits along the duct 8 and enters the container 16 through the inlet duct 17. During this stage a chamber is created at the pressure of the filling gas, formed by the ducts 8 and 9 and by the securing element 4 and the container 16, which prevents the ball 12 being able to move of its own accord.
The system for filling must be correctly dimensioned to be able to carry it out in a short time. The diameter of the inlet duct 17 is calculated to carry out the filling in a determined time and under conditions of Mach 1 flow at ambient temperature.
The configuration of the filling and closure device 1, holding the container 16 and including the chamber 13 permits that the filling of the container 16 may be carried out.
Having completed the filling there is initiated the blocking stage of the duct 17 of the container 16 which will be described below, following Figures 4 and 5.
The blocking stage is commenced by the activation of the piston 11 which provides the required thrust to the steel ball 12 for it to be introduced into the gas inlet duct 17 of the container 16 and to serve as blocking element of the same. With F/D (force/displacement) control, correct closure is ensured.
The ball 12 must be made of a softer material than that of the container 16 to perfectly fulfil its function as closure element.
Piston 11 has a diameter somewhat greater than that of the filling duct 17 of the container 16, thus to obtain a sufficient cross-section for clinching.
The blocking stage ends when the piston 11 impacts against the container 16 producing the penetration of the ball into the inlet duct 17 and the closure clinching.
Following Figures 6 and 7, which show the container 16 subsequent to its extraction from the device 1, it may be seen that the lateral surfaces 12' of the ball 12 have been forced against the container 16 and that the lower part of the latter has been configured as a plane surface 12" of the ball 12 and the deformed part 18 of the container 16, inside the duct 17.
As may be observed in Figures 1 and 7 the inlet duct 17, of the container 16 has an inlet mouth 23 of larger diameter. In Figure 7 there is shown the depth s of the inlet mouth 23 to be able to realise the sealing of the container by means of welding with the provision of material and the clinching distance h which the piston 11 produces.
Finally, and as illustrated in Figures 8, 9 and 10, the sealing stage is proceeded to by means of a circumferential weld 24 which seals the container 16 at the zone external to the ball 12.
In Figure 8 is shown the sealing device employing an arc welding device. This device comprises a welding gun 19, welding wire 21 and shielding gas (Ar/He) 20.
Finally, there will be described the step-by-step procedure of filling and closure of the gas container:
Step 1.- Positioning of the container 16.
Step 2.- Generation of the groove 6' in the form of an inverted V in the container 16 due to the application of a constant compression force F.
Step 3.- Opening of the pressure valve of the filling system 10 and filling of the container 16.
Step 4.- Control of the pressure as a function of time. If the pressure obtained is correct process A is followed and if it is not process B is followed, both described below:

Process A (correct pressure):

Step 5A.- Driving and deformation of the ball 12.
Step 6A.- Withdrawal of the deforming piston 11.
Step 7A.- Controlled displacement of the upper piston 14 and unloading of the part.

Process B (incorrect pressure):

Step 5B.- Withdrawal force F.
Step 6B.- Controlled displacement of the upper piston 14.
Step 7B.- Removal of the part and checking of the system.
The estimated compression force F which must be applied to the upper piston must exceed:
F > n (P x Π d1² / 4 + F1), where n is an integer, d1 is the diameter between the grooves, P is the pressure in the chamber 13, F1 is the force applied in the groove and F is the force applied to the piston 14.
With reference to the embodiment described of the invention, those modifications comprised within the scope defined by the following Claims may be introduced.

Claims

Procedure for filling a container (16) with a pressurised gas and of closure of the inlet duct (17) to the container (16), which includes a first stage of filling with the gas provided by a filling system (10) connected by ducts (8, 9) to the gas inlet duct (17) to the container (16) and a second stage of blocking the said gas inlet duct (17) with a metal ball (12), characterised in that:

a) the said second stage is realise in such a manner that the ball (12) remains situated in the interior of the gas inlet duct (17), with its lateral surfaces (12') driven against it and with its lower part deformed to form a plane surface (12");

b) the procedure comprises a third stage of sealing the gas inlet duct (17) to the container (16) by means of the application of a circumferential weld (24) which seals the container (16) at the zone external to the ball (12).
Device for filling a container (16) with a pressurised gas and the blocking of the gas inlet duct (17) to the container (16), which includes means (2, 3, 4 and 7) to couple it in a gas-tight manner to the container (16) and filling it with a gas provided by filling system (10) by means of ducts (8, 9) and means to effect the blocking of the said duct (17) with a metal ball (12), characterised in that the said means of blocking comprise a piston (11) capable of forcefully driving the ball (12) into the interior of the duct (17) and deforming its lower part in the form of a plane surface (12").
Device for filling a container (16) with pressurised gas and blocking the gas inlet duct (17) to the container as claimed in claim 2, characterised in that said means of coupling (2, 3, 4 and 7) include a positioning element (4) with lips (6) destined to produce by compression a groove (6') in the lower base of the container (16) to impede the escape of gas to the exterior during the filling stage.