EP0396639A1

EP0396639A1 - Means and device for generating vacuum in a closed vessel

Info

Publication number: EP0396639A1
Application number: EP19890906856
Authority: EP
Inventors: Moens Jensen-Plambech
Original assignee: VACEX AB
Current assignee: VACEX AB
Priority date: 1988-05-24
Filing date: 1989-05-23
Publication date: 1990-11-14
Also published as: DK18590A; DK18590D0; SE8801917D0; AU3753589A; FI900316A0; SE8801917L; WO1989011389A1

Abstract

Un tube élastique (8) dont l'intérieur peut être mis en communication avec une source de pression (7) est agencé dans un récipient (1) fermé rempli d'un fluide. Lorsqu'il est mis sous pression, le tube se gonfle et expulse une quantité du fluide contenu dans le récipient (1) à travers une soupape (5) associée au récipient (1). La soupape (5) est ensuite fermée et l'intérieur du tube (8) est dépressurisé, ce qui entraîne la contraction du tube (8) et crée le vide à l'intérieur du récipient fermé (1).An elastic tube (8), the interior of which can be brought into communication with a pressure source (7), is arranged in a closed container (1) filled with a fluid. When pressurized, the tube inflates and expels a quantity of the fluid contained in the container (1) through a valve (5) associated with the container (1). The valve (5) is then closed and the inside of the tube (8) is depressurized, which causes the tube (8) to contract and creates a vacuum inside the closed container (1).

Description

Means and device for generating vacuum in a closed vessel.

The invention relates to a method and device for creating low pressure in a closed vessel. There is a need for low pressure in several fields of application, e g in the manufacturing industry, where a controllable sucking power is essential in connection with power transmission or materials handling. Examples of such fields are hydraulic equipments for which there is a great need for high pressure and low pressure, e g in a cylinder provided with a piston in which the high pressure pushes the piston forwards and the low pressure retracts it. Another example is the coating of solid bodies with a cover of elastic material. Coating solid bodies with a cover of elastic material often causes problems due to the considerable forces that are required for expanding e g an elastic sleeve in order to introduce a body into the sleeve. There exist devices, e g mechanical apparatuses, for coating bodies with a cover of elastic material through expansion of the latter, where¬ by considerable forces are required for retraction of the expansion device after the aforesaid expansion. The sleeve can of course also be expanded with compressed-air. This method has many inconveniences as every sleeve size requi- res its specific expansion device. Due to the supply of compressed-air into the inner volume of the sleeve, it is further of vital importance that the wall of the sleeve is tight, as any minor leakage of compressed-air necessitates rejection of the sleeve. For that reason also this method causes problems and primarily considerable costs. Neither it is with prior art methods possible to obtain such a big contact pressure between the elastic sleeve and the body that a special adhesion medium between the body and the sleeve can be avoided. With the present invention the above-mentioned incon¬ veniences can be evaded by creating a low pressure in a closed vessel , the shape of which can be adapted for the desired area of application. This object is achieved in that the vessel, which has the shape of a closed casing, in its wall has a first wall entrance for the provision of pressure medium and a second wall entrance which is connec¬ ted to a valve. In the vessel there is an elastically defor able chamber, e g in the form of a rubber tube, which extends helically along the inner surface of the walls of the chamber. The elastically deformable chamber is in its one end tightly connected to a valve in the f,irst wall entrance for the provision of pressure medium and in its other end tightened with a plug. In the wall of the chamber there is a cover, e g consisting of flanges, which is arranged so that, by removing or adding flanges, an opening kan be increased, reduced or completely closed. A medium, e g water, is introduced into the vessel in a quantity which corresponds to the inner volume of the vessel reduced with a volume corresponding to the expansion ability of said chamber. Thereafter the vessel is closed with the cover, whereafter the pressure medium, e g air, is introduced into the chamber which hereby expands. In the first case water is after a certain time let out through said valve, whereby this is instantly closed, the supply of pressure medium is stopped and the excess pressure in the chamber is let off. The walls of the chamber thereafter, due to the in them built-in tension, are striving to resume their original shape and transfer a considerable low pressure to the surrounding medium. By^' choosing an elastically deformable chamber with walls of considerable thickness and good elasticity, according to the invention a substantial low pressure can be obtained in the closed vessel, which can be utilized in outer devices requiring low pressure. An important field of application for the invention is the coating of solid bodies with a cover of elastic material, preferably rubber, in the shape of a sleeve with relatively thick walls and an appropriate length. The sleeve is with a tightening device shut tight in its one end. The other end of the sleeve is provided with an expan¬ sion device with the help of which this open end can be expanded. An opening is created in said cover by removing so many of said flanges that the desired opening area is obtained. The tightened sleeve, which is shut with the expansion device, is introduced into the vessel until the expansion device at the open end of the sleeve bears upon said opening in such a way that the expansion device toget¬ her with the open end of the sleeve create a cover against the vessel. The valve in the wall of the vessel is opened, whereafter the pressure medium, preferably water, is let into the elastically deformable chamber from a compressed- air unit. The compressed-air is now widening the elastical¬ ly deformable chamber, which in its turn presses the medi- um, which is let into the vessel, out through the valve.

When the medium starts to emerge outwards through the valve this is shut, the supply of pressure medium into the elas¬ tically deformable chamber is stopped and the compressed- air is let out of the elastically deformable chamber via a valve connected to the compressed-air unit. Hereby the sleeve of elastic material is widened in proportion to the contraction of the elastically deformable chamber and the cross section of the sleeve is substantially widened. A solid body, with a cross section that is much bigger than the original cross section of the sleeve, can now be intro¬ duced into the sleeve, whereafter the valve is opened and air starts to flow into the vessel, whereby the sleeve contracts to a firm grip around the solid body, which hereby is being provided with a cover of elastic material, preferably rubber.

The invention is being described in detail below with reference to the accompanying drawing, which illustrates an embodiment and in which:

- figure 1 illustrates, from the side and in section, a device for creating low pressure, which through a valve is connected to a unit requiring low pressure, and

- figure 2 illustrates schematically, using the device according to figure 1, a method of coating a body with a cover of elastic material, preferably rubber. In figure 1 is shown in section a vessel 1 of a rigid material, preferably steel. In the upper part of the vessel 1 is a cover 2. The cover 2 is made of a number of flanges 3, which are arranged tightly against one another, and of which the lower one is tightly assembled to the upper part of the vessel 1. Said flanges 3 together form a tight unit. At the upper end of the side wall 4 of the vessel 1 is arranged a valve 5, which easily can be opened and shut. In the lower part of the vessel 1 is arranged a wall entrance 6, which is constructed in such a way that a connection unit, preferably that of a compressed-air unit, can be coupled to the wall entrance 6, which in its turn inside the vessel 1 easily can be connected with an elastically deformable chamber 8. This closed chamber 8 is in the shown embodiment a tube of non-reinforced rubber, which helically extends to the upper part of the vessel 1 along the side wall 4. The upper part of the elastically deformable cham¬ ber 8 is tightened with a plug 9. The upper wall 10 of the vessel 1 and its lower wall 11 are tightly connected with the side wall 4 of the vessel 1.

An elongated body of a rigid material is now to be coated with a cover of relatively thick elastic material, which cover has the shape of an appropriate sleeve with sufficient wall thickness and a cross section area, which in uncharged state is considerably smaller than the cross section area of the body to be coated.

This sleeve, which is indicated with 12 in figure 2, has of course a length appropriate for said body. First one end of the sleeve 12 is tightened, e g with a spring device 13. The other end of the sleeve 12 is provided with an expansion device in the shape of a collar 14, which has a somewhat bigger cross section area than the body to be coated. The open end of the sleeve 12 is pulled over the collar 14 so that the sleeve 12 together with the collar 14 forms a funnel for introducing said body.

The upper one of the flanges 3 in the cover 2 is removed. Also are additionally removed so many of the flanges 3 that the cross section area of the collar 14 becomes somewhat bigger than the cross section area of the upper one of the remaining flanges 3. The vessel 1 is filled with a medium 15, preferably water, in such a quan¬ tity that in the vessel 1 remains an air bubble 16, the volume of which corresponds to the desired expansion of the sleeve 12. The end of the sleeve 12, which is tightened with the spring device 13, is led into the vessel 1, until the collar 14 bears on the upper one of the remaining flanges 3, whereby the collar 14 forms a cover against the vessel 1. The valve 5 is opened, a compressed-air unit 7 is activated and air is with great pressure pressed into the elastically deformable chamber 8, which thereby is widened and presses the medium 15 against the upper Wall 10 of the vessel 1. Hereby the air bubble 16 is reduced by letting the air in the vessel 1 out of the same through the valve 5. When water 15 is beginning to emerge through the valve 5 this is shut, the supply of compressed-air from the com¬ pressed-air unit 7 is stopped and the compressed-air in the elastically deformable chamber 8 is let back out via a valve connected to the compressed-air unit 7, whereby the elastically deformable chamber 8 contracts due to the power built into its wall. As the sleeve 12 is made of an elastic material it is widened in proportion to the contraction of the elastically deformable chamber 8, because the vessel 1 cannot change its shape and because the medium 15 has a constant volume under the prevailing pressure and tempera¬ ture conditions. Leakage through the collar 14 cannot occur because this is with great force sucked against the upper one of the remaining flanges 3.

Into the sleeve 12, which is widened with the above- mentioned method, now easily and with no additional force can be introduced a body 17, which has an outer cross section area that is considerably bigger than the original cross section area of the sleeve 12. After the introduction of the body 17 into the sleeve 12 (figure 2) the valve 5 is opened, whereby air can flow into the vessel 1. Thereby the low pressure is relieved and the sleeve 12 of elastic material can resume its original dimension, which entails that the sleeve 12 with considerable force is pressed against the outer surface of the body 17, which in its turn imposes that the sleeve 12 is practically impossible to remove without being destroyed. The body 17, with its cover in the shape of the sleeve 12 of elastic material, is now lifted out of the vessel 1 through the opening in the upper wall 10, whereafter the collar 14 and the spring device 13 are removed and the excessive part of the sleeve 12 is taken away. Now there has been achieved a body with a very well adhered cover of elastic material. For this reason no special adhesion medium between the body and the sleeve is required. Neither has the outer surface of the body and/or the inner surface of the sleeve to be specially treated in order to increase the friction in the contact surface.

The above-mentioned embodiment is but one out of many methods of using the device according to the invention. The described device has a very simple construction and is primarily intended for manual operation. A person skilled in the art realizes that it is easy to automatize the device using hydraulic or electrical handling organs toget¬ her with appropriate control facilities. Consequently the invention is not limited to the shown and described embodi¬ ment, but can be altered within the scope of the patent claims.

Claims

1. A method for creating low pressure in a vessel (1), c h a r a c t e r i z e d in that the vessel (1) is filled with a medium (15), preferably water, until an appropriate air bubble (16) is obtained in the upper part of the vessel (1), that in the vessel (1) is arranged an elastic chamber (8) , which, due to supply of .a pressure medium, preferably air, can be widened and that way press the medium (15) against the upper wall (10) of the vessel (1) via an open, and closable, valve (5), which is arranged at the upper wall (10) of the vessel (1), whereby the air bubble (16) is removed from the vessel (1), that when the medium (15) is beginning to emerge out of the valve (5) this is shut and the provision of the pressure medium from a compressed-air unit (7) is stopped, that thereafter the excess pressure in the elastically deformable chamber (8) is released, whereby the chamber (8), due to its relatively thick walls and great elasticity contracts and tries to resume its original shape and thereby in the vessel (1) is obtained a considerable low pressure, which is not relieved until the valve (5) is opened and thus air or other medium is allowed to flow into the vessel (1).

2. A method for creating low pressure in a vessel (1) according to Claim 1, c h a r a c t e r i z e d in that the air bubble (16) in the vessel (1) is widened so that it fills the whole inner volume of the vessel (1).

3. Device for creating low pressure in a closed vessel (1), c h a r a c t e r i z e d by a vessel (1) of a rigid material, e g steel, which is dimensioned according to the field of application, with a wall entrance (6) for the provision of a pressure medium arranged in the wall (4) of the vessel (1), with a valve (5) arranged at the upper part of the wall (10) of the vessel (1), which valve can be opened and shut, an elastic chamber (8) in the shape of a tube with relatively thick walls, which is arranged so that its one end is firmly connected to the wall entrance (6) and its other end is tightened with a plug (9) or other tightening device, and so that it extends helically along the inner surface of the wall (4) of the vessel (1).

4. Device according to Claim 3, c h a r a c t e r ¬ i z e d in that the elastic chamber (8) is shaped so that it creates an inner, stretchable wall in the vessel (1) and so that the pressure medium via the wall entrance (6) has free access to the space between the walls of the vessel (1) and the elastic chamber (8).

5. Device according to Claim 3 or Claim 4, c h a ¬ r a c t e r i z e d in that the upper wall (10) of the vessel (1) is provided with a cover (2) consisting of a number of flanges (3), which are bearing tightly on one another and which are provided with gaskets, having such dimensions that, if a suitable number of the flanges (3) are removed, is created a pyramid-formed inlet opening, that matches a collar (14) for an elastic sleeve (12) which is introduced into the mentioned inlet opening and the flanges (3) of which can shut tight the mentioned inlet opening.

6. Device according to any of the Claims 3 - 5, c h a r a c t e r i z e d in that the valve (5) in the upper part of the wall (10) of the vessel (1) can be con¬ nected to an organ which utilizes the low pressure in the vessel (1) , which low pressure is obtained through the provision of a pressure medium to the mentioned elastic chamber (8) and the release thereafter of the excess pres- sure in the elastic chamber (8) after the shutting of the valve (5).

7. Device according to any of the Claims 3 - 6, c h a r a c t e r i z e d in that the elastic chamber (8) can have an elongated, tubular, cubical or spherical shape.

8. A method for creating low pressure in a closed vessel (l) according to any of the Claims 1 - 2, c h a ¬ r a c t e r i z e d in that a sleeve (12), of elastic material, preferably rubber, and with relatively thick walls, is provided with an expanding collar (14) in an open one of its ends, and is closed with a plug or a spring device (13) at its other end, that one or several of flang¬ es (3) of a cover (2) are removed, whereby is obtained an inlet opening through which the sleeve (12) is introduced with its one end, which is tightened as mentioned above, first, whereafter the collar (14) will bear on the outer one of the remaining flanges (3) in such a way that the sleeve (12) with its plug or tightening device (13) and its collar (14) replace the cover (2) and one or more of the flanges (3), that the valve (5) thereafter is opened and the pressure medium is let into the elastic chamber (8), whereby this expands and air is pressed out of the valve (5), whereafter the valve (5) is shut as soon as the medium (15) begins to emerge through it, the compressed-air unit (7) is stopped and the excess pressure is let out of the elastic chamber (8), which thereby contracts, whereafter the elastic sleeve (12) is widened in proportion to the contraction of the elastic chamber (8) , whereby the inner cross section area of the sleeve (12) is considerably increased.

9. Device according to any of the Claims 3 - 7, c h a r a c t e r i z e d in that the vessel (1) in its lower wall (11) is provided with an opening, a cover (2) and flanges (3) for the connection of the sleeve (12) to said opening.

10. A method for creating low pressure in a closed vessel (1) according to Claim 1 or 2 and using a device according to Claim 9, c h a r a c t e r i z e d in that the plug or tightening device (13) of the sleeve (12) is removed and is replaced by a collar (14), which is connec¬ ted to the opening in the lower wall (11) of the vessel (1), whereby the sleeve (12) creates a cavity which runs through the whole of the vessel (1).