Patent Application
20100230118
The present invention relates to a fluid ejection device, in particular to an extinguisher or an emergency hydraulic generator used in an aircraft.
As regards the use of fluid ejection devices as an extinguisher, it is known that extinguishers with a reservoir of extinguishing agent are classified in two large categories. The first category relates to permanently pressurized apparatuses in which a gas ensures permanent pressurization of the extinguishing agent within a single bottle used as a reservoir for it; the extinguishing agent is released through a valve at the outlet of said bottle. In the second category, a propellant gas is only released upon putting the extinguisher to use and releases the extinguishing agent which is therefore not stored under pressure.
As an illustration of an extinguisher of the first type, extinguishers presently used for putting out an aircraft engine fire may be considered. These devices, not only allow the fire to be put out, but also prevent any extension of said fire. The extinguishing agent is contained in a bottle, most of the time with a spherical shape, pressurized by an inert gas; one or more distribution ducts, connected to said bottle, allow distribution of the agent towards the areas to be protected. At the lower end of the bottle, a calibrated cap allows each distribution duct to be blocked. A pressure sensor is also installed in order to continuously check the pressurization of the bottle. When a fire is detected, a pyrotechnic detonator is triggered. The resulting shock wave allows the blocking cap to be pierced, which causes emptying of the bottle and discharge of the extinguishing agent under the effect of the pressure contained in the bottle towards the areas to be protected, via the ducts.
A significant drawback of this type of pressurized extinguishers is their sensitivity to microleaks, which submits them to severe monitoring, inspection and maintenance conditions. Moreover, the extinguishing agent does not completely fill the bottle since the latter should be able to contain the pressurization gas.
As regards the extinguishers of the second category, they use a separate pressurization device. These fire fighting devices are generally equipped with a first reservoir of compressed gas and with a second reservoir for the extinguishing agent. When the device is used, the compressed gas contained in the first reservoir is put into communication via an orifice with the second reservoir of extinguishing agent for the pressurization of the bottle containing the extinguishing agent. When the extinguishing agent is pressurized, it is ejected for fighting the fire, like for the devices of the first extinguisher category.
In certain cases, for extinguishers of the second category, the first reservoir of compressed gas may be replaced by a gas generator, as described in document EP1552859.
This type of extinguisher may comprise a separation means, for example a membrane or a piston, placed in the reservoir so as to define a first enclosure called a pressurization chamber, and a second enclosure containing the extinguishing agent. The purpose of this separation means is to limit heat transfers between the generated gas and the extinguishing agent, as described in document EP1819403 filed in the name of the applicant. Indeed, in the absence of thermal insulation, the extinguishing agent may rapidly absorb the calories of the generated gas and thereby reduce the efficiency for ejecting the extinguishing agent.
However, the performances of such extinguishers may further be optimized. Indeed, an extinguisher used in an aircraft should remain operational over a wide temperature range, notably from about −55° C. because of the high altitude at which the airplane flies, to about +95° C. Depending on the temperature, the extinguishing agent may be subject to large volume variations. These volume variations may induce overpressure in the pressurization chamber, which has several major drawbacks.
Indeed, the constraints as regards safety imposed by international regulations in the aeronautical field make the implementation delicate and complex of devices subject to internal overpressure close to areas which may be supplied with extinguishing agent, in particular in proximity to the engines. Indeed, these devices are likely to be damaged during exterior incidents, for example by ejection of engine parts, by heat or flames. In the same way, explosion of these devices may damage the relevant areas.
In order to meet this regulatory requirement, a solution may consist of producing the extinguisher in a particularly secured way, for example with large wall thicknesses. This solution leads to an increase in the overall mass of the extinguisher, which is a penalty for the performances of the aircraft.
Another solution may consist of moving the extinguisher sufficiently away from the relevant areas. However, moving it away requires the use of a greater distribution duct length between the extinguisher and said areas, which increases the linear pressure loss in the duct and reduces the ejection efficiency. Further, the required significant duct mass is also a penalty.
Of course, the problem remains identical in the case of a use of the fluid ejection device as an emergency hydraulic generator for an aircraft, wherein any overpressure in the ejection device should be avoided in the idle phase while ensuring optimum ejection efficiency.
A fluid ejection device for fire fighting usually comprises, as shown in
If a large amount of fluid is required and if it is not possible, taking into account the confinement of the space, to install a large volume reservoir in proximity to the extinction point, or, if for regulatory reasons, having several independent systems or redundancy is imposed, it may be necessary to couple several reservoirs in parallel on the same circuit. In this according to a first embodiment, a first pressurized tank is emptied by opening its connection valve A2 and then the valve is closed and this second pressurized reservoir is emptied by opening its connection valve which is then closed upon ending the emptying and so forth. Closing each valve upon ending the emptying is necessary in order to prevent the fluid ejected from a reservoir, the valve of which has been subsequently opened from filling the previously emptied reservoir(s) instead of being directed towards the extinction point.
This requires a complex control system and valves able to be driven in both directions, opening and closing, i.e. containing mobile parts and subject to sealing defects. The complexity of such a device makes its maintenance costly and reduces its reliability when it is used for safety devices where said device may remain passive for years and should operate perfectly when the time comes.
Thus, the use of a reservoir containing the extinguishing agent at atmospheric pressure is for example known from patent EP1502859B1, or EP1819403. The latter is pressurized either by putting it in communication with a bottle of compressed air or nitrogen, or via a pyrotechnic gas generator directly placed inside the reservoir or nearby and connected to the latter. In the latter case of pressurization of the reservoir, with the membrane separating the fluid from the gases generated by a pyrotechnic reaction of the device according to EP1819403 it is possible to prevent the fluid from absorbing the calories of this reaction and from reducing its efficiency. Such a fluid reservoir is put into direct communication with the distribution circuit, the connection being closed by a tearable cap for a given pressure. This cap plays the role of the valve. Thus, in order to trigger the emptying of the device, it is sufficient to introduce the pressurized gas from the bottle into the reservoir or to trigger the pyrotechnic generator. The differential pressure applied on the cap, the distribution circuit being empty and at atmospheric pressure, while the pressure increases in the reservoir, causes tearing of the latter, thereby allowing the fluid to be poured into the distribution circuit A4 towards the extinction point A5.
This device is more reliable since it does not comprise any moving parts at the valve, parts for which the seal must be ensured and the operation must be guaranteed, notably the absence of jamming, over time.
On the other hand, once the cap is pierced, the latter can no longer ensure closure of the connection of the reservoir with the distribution circuit.
In such situations and wherever the use is provided of valves which are only controllable upon opening, it is possible to insert anti-return valves A3 into the distribution circuit. Such valves only let through the fluid in one direction of flow (direction of the arrow in
So many valves generate pressure losses in the circuit and also have to be subject to regular monitoring in order to ensure their operability. Indeed, as the distribution circuit A4 is empty when the device is not operating, i.e. during times which may attain years, such valves may be subject to jammings caused by condensation which may occur in such circuits, particularly when the device is installed in an aircraft in a non-pressurized area and is therefore subject to temperature and pressure variations over a large amplitude during each flight.
Thus, there exists a need for a device allowing a plurality of fluid reservoirs to be mounted in parallel with view to their sequential triggering without generating excessive pressure losses in the circuit and while preserving operating reliability comparable to that which would be obtained with a single reservoir.
As described earlier, the fluid ejection device according to the prior art comprises a reservoir containing the fluid intended to be ejected, one end of said reservoir including controllable blocking means, such as a valve, capable of putting the fluid in communication with the outside of the reservoir so as to cause its flow.
According to an embodiment, the fluid is thus stored under pressure in the reservoir. The reservoir is connected to a distribution circuit via the valve, the opening of the latter causing ejection of the fluid into the distribution circuit.
According to another embodiment of the prior art, the fluid is not stored under pressure in the reservoir. In order to cause ejection of the fluid, the pressure in the reservoir has to be increased before opening the valve for communication with the distribution circuit. This effect is obtained either by putting the inside of the reservoir directly into communication with a pressurized fluid, for example with compressed air, or by compressing the fluid intended to be ejected via a separating element located inside the reservoir. Such a separating element may be formed by a membrane or by a piston which sealably separates the reservoir into two chambers, one of which containing the fluid intended to be ejected. As the volume of the reservoir is fixed, the pressurization of the fluid to be ejected and its ejection out of the reservoir are accomplished by increasing the volume of the chamber not containing the fluid. Such a volume variation is obtained by moving the separating element either by a purely mechanical device, or by increasing the pressure in the chamber not containing the fluid intended to be ejected. This pressure increase is obtained by injecting into said chamber, called a pressurization chamber, a pressurized fluid.
As both chambers of the reservoir are sealably separated by the separating element, any fluid type may be used without any risk of it not mixing with the fluid intended to be ejected. As an example, this may be compressed air or nitrogen. Advantageously, the fluid injected into the pressurization chamber is generated by a pyrotechnic gas generator, and, according to a particularly advantageous embodiment of the prior art, said pyrotechnic generator is directly located in the reservoir, inside the pressurization chamber.
Finally, the controllable means for blocking the chamber containing the fluid intended to be ejected, may assume the shape of a cap which breaks for a given pressure of said fluid. Under these conditions, a compact device is obtained, including all the means for triggering ejection of the fluid. Such a device is described in European patent application EP1819403 filed in the name of the applicant.
Further, the separating element thermally insulates the pressurization chamber of the fluid intended to be ejected. Thus, when using this device as a fire-fighting device, the fluid to be ejected is for example an extinguishing agent in a liquid phase. This type of fluid may have very high heat capacity and the separating element prevents the pyrotechnic reaction generating the pressurization gas from being slowed down by the absorption of heat by the extinguishing agent.
Among all these embodiments of the prior art, the one which uses a reservoir with a substantially cylindrical shape separated into two chambers by a piston, is the most efficient in terms of ejection of the fluid, i.e. this embodiment maximizes the ratio between the fluid volume actually poured into the distribution circuit and the fluid volume initially contained in the reservoir.
In this type of device, the ejection sequence is carried out in five essential phases:
1. The triggering of the gas generator causes a pressure increase in the pressurization chamber and correlatively, via the piston, in the chamber containing the fluid.
2. Beyond a defined pressure threshold, the cap of the chamber containing the fluid to be ejected breaks, putting said fluid in communication with the distribution circuit.
3. The separating element may then move and push the fluid into the distribution circuit.
4. When the piston arrives at the end of travel, means lock the piston in this position so as to avoid any return of the fluid towards the reservoir.
5. Specific means forming a valve then enable the gases from the pressurization chamber to flow towards the distribution circuit in order to purge said circuit.
The pressure, both in the pressurization chamber and in the chamber containing the fluid to be ejected, is high at the beginning of the triggering and passes through a maximum when the cap breaks. It then decreases in order to attain a value close to atmospheric pressure at the end of the discharge.
Such a device is a single use device.
When it is used as a fire-fighting device or as an emergency device, it may remain inactive for very long periods, which may attain several years and will have to nonetheless operate perfectly when the time comes. Now, as the piston is caused to slide inside the reservoir, it is difficult to ensure a perfect seal between both chambers while preserving easy slidability of the piston and this for periods which may attain several years.
Thus, according to these embodiments of the prior art, small amounts of fluid to be ejected end up infiltrating the pressurization chamber.
If said pressurization chamber is in communication with the outside air, this fluid may evaporate. The thereby evaporated fluid is lost, reducing in proportion the amount of fluid capable of being ejected. If the pressurization chamber is sealed against the outside, then accumulation of this fluid in the latter reduces in proportion the efficiency of the pyrotechnic reaction and subsequently that of the ejection of the fluid.
Moreover, particularly if the pressurization chamber is in communication with the outside, condensation phenomena may occur therein. Water thereby introduced into this chamber may, in the long run, mix with the fluid to be ejected, with the risk of degrading the characteristics of use of the latter.
Finally, even if it remains possible to guarantee the seal of the piston when the device is at rest, the first phase of the ejection remains a critical phase because of the rapid pressure variations which occur during this phase. The seal may also be preserved under these pressure conditions.
There is therefore a need for a compact fluid-ejecting device including two chambers separated by a separating element of the piston type, the seal of which between both chambers is perfect and durable without however degrading the slidability of the piston.
In order to solve at least in part the insufficiencies of the prior art, the invention proposes a fluid ejection device comprising a reservoir of a substantially cylindrical shape, a separating element dividing it into two chambers, sealing means between the separating element and the side walls of the reservoir, said separating element being slidable in the reservoir along the longitudinal axis of the latter so as to modify the relative volume of the chambers, a first chamber being filled with a fluid and being provided with an orifice closed by a cap so that said fluid may be ejected under pressure from the reservoir through said orifice under the effect of the translational movement of the separating element and of the opening of the cap as well as means capable of modifying the pressure in the chamber not containing any fluid, a so-called pressurization chamber, in order to cause translational movement of the separating element. According to the invention, said pressurization chamber further comprises a thimble capable of sealably separating the inside of the pressurization chamber from the sidewalls of the reservoir.
Thus, possible leaks of fluid to be ejected which may occur between the separating element and the wall of the reservoir remain confined between the wall and the thimble. Therefore there is no risk of losing fluid to be ejected notably by evaporation of the latter in the pressurization chamber, nor is there any risk of mixing condensation products of the pressurization chamber with the ejection fluid.
Advantageously, the thimble is capable of constantly providing the seal between the pressurization chamber and the walls of the cylinder between two longitudinal positions of the separating element. This allows preservation of the seal during movements of the piston notably generated by heat expansion of the fluid to be ejected, as well as during at least one part of the first two phases of the discharge.
Advantageously, said thimble consists of a diametrically expansible flexible material. Thus, in addition to causing translational movement of the piston, the pressure increase in the pressurization chamber causes expansion of the thimble, pressing it against the walls of the reservoir. The thimble therefore continues to provide the seal between both chambers even in the presence of higher pressure. With this effect, the operation of the device may be secured even if the sealing means between the piston and the walls of the reservoir have slightly degraded over time and are no longer capable of providing a perfect seal under pressure, therefore particularly at the beginning of the ejection just before and immediately after the opening of the cap.
As soon as the cap is broken and that flowing has begun, the pressure of the fluid to be ejected is just only dependent on the characteristic and the pressure losses of the distribution circuit. During the second phase of the ejection, the efficiency of the device depends on the capability of the piston of sliding rapidly. It is therefore advantageous that, during this phase, the piston should not be slowed down in its translation through the thimble. Thus, according to an advantageous characteristic, the seal of the thimble is broken beyond a defined longitudinal position of the separating element. This characteristic also allows the distribution circuit to be put into communication with the pressurization gases in order to purge it during the fifth phase of the discharge.
The continuity of the seal of the thimble between both defined longitudinal positions of the piston may be ensured by the longitudinal elastic extension of said thimble particularly if the latter consists of a flexible material. However, advantageously, this longitudinal extension is facilitated when the thimble includes at least one fold capable of being unfolded under the effect of the translational movement of the separating element. With this characteristic, it is possible to use for making up the thimble, a thicker therefore more pressure-resistant material and, if necessary, more temperature-resistant during the first two phases of the discharge. This embodiment is therefore particularly advantageous when the device includes a pyrotechnic gas generator in communication with the pressurization chamber, the triggering of which allows the discharge to occur.
By the combination of these characteristics, a compact ejection device may be formed, the seal of which between the chambers is strengthened. Advantageously, such a device includes a device capable of putting the pressurization chamber in communication with the outside in order to retain constant pressure therein with regard to the slow volume variations and close said chamber with regard to pressure and volume variations generated by the activation of the pyrotechnic gas generator. With this characteristic, it is possible to keep the ejection device free of any internal overpressure outside the operating phases, which improves its safety and allows reduction of its bulk and weight. Indeed, as it is not permanently subject to internal pressure, the device may be built with walls of smaller thickness without degrading its reliability towards risks of bursting.
According to an embodiment which is particularly adapted to the use of a fluid ejection device as a fire-fighting device, the latter includes means capable of putting the gases generated by the pyrotechnic reaction in communication with the fluid distribution circuit upon ending ejection of the fluid. The circuit may thereby be purged on the one hand and thus benefit from the whole amount of the extinguishing agent, and a discharge in two phases may also be obtained: the first consisting of pouring a large amount of extinguishing agent onto the fire, the second consisting in blowing onto the fire area an aerosol consisting of the gas generated by the pyrotechnic reaction and of the extinguishing agent.
By injecting a pure agent in this first discharge phase, it is thereby possible to obtain maximum concentration of the extinguishing agent which is the most often sought criterion within the scope of certification of an extinguishing system in particular for engine fire extinction applications in the aeronautic field.
In the second phase, by ejecting the aerosol formed by the pressurization gas, the actual nature of the gas (inert) may usefully participate in the extinction phase on the one hand, and the agent may be properly distributed wherever it is useful in the fire area to be treated on the other hand.
A device according to the invention may include means capable of preventing any return of gas or fluid from the distribution circuit into the reservoir after complete discharge of the latter. This allows an increase in the efficiency of the device and notably maximization of the ratio between the actually poured fluid and the fluid initially contained in the reservoir; this also allows parallel coupling on the same distribution circuit of several reservoirs of this type in order to have available a larger amount of fluid to be ejected. In this case, the different reservoirs are sequentially triggered without any risk that the discharge of one of the reservoirs fills another of them, already emptied, instead of being poured at the targeted point.
For using the device according to the invention for fire-fighting, the fluid to be ejected is advantageously an extinguishing agent of the fluoroketone type.
Alternatively, such a device may also be used as an ultimate emergency hydraulic generator; in this case the ejected fluid is hydraulic oil which may thus ensure ultimate emergency pressurization of any hydraulic circuit.
Such devices are more particularly suitable for use in aircraft, because of their compactness, their reliability and their reduced weight and of their low sensitivity to pressure and temperature variations.
The object of the invention according to another aspect of the invention is an ejection device for ejecting a fluid including:
a reservoir comprising a cylindrical body sealably closed at its ends by first and second end portions, said reservoir comprising said fluid,
means for generating pressurized gas,
a rigid separation means, mobile along the axial direction of said reservoir, localized between the first end portion and said fluid so as to sealably form a first enclosure and a second enclosure containing said fluid, and
communication means for putting the reservoir in communication with said generation means so that the gas generated by said generation means may penetrate into said first enclosure of said reservoir,
an ejection orifice located in the second end portion,
a pressure control means being positioned in the first end portion, and capable of adopting an open configuration in the absence of said generated pressurized gas in the reservoir so as to ensure that said first enclosure is exposed to the open air of the outside environment regardless of the axial position of the separation means, and a closed configuration in presence of said generated pressurized gas in the reservoir so as to provide the seal of said first enclosure.
Advantageously, closing of the pressure control means is controlled by the pressure exerted by said generated pressurized gas in said first enclosure.
In an embodiment of the invention, the pressure control means comprises a valve body with a substantially tubular shape, the inner face of which includes a valve seat, said valve body including at least one conduit for communicating with the outside environment of the reservoir, and a mobile part along the axial direction of the valve body and including a head adapted so as to come into contact with said valve seat thereby defining said closed position of the valve.
Advantageously, the pressure control means further comprises a separation means mobile along the axial direction of the valve body and positioned radially between the valve body and the mobile part, said separation means being capable of moving so as to face said communication conduit of the valve body.
Preferably, as the ejection device comprises distribution means connected to the ejection orifice, said communication conduit of said valve body is connected to said distribution means.
Preferably, a spring means is positioned in said first enclosure of said reservoir so as to exert a compressive force on said separation means along the axial direction of said reservoir, towards the second end portion, regardless of the axial position of the separation means.
In an embodiment of the invention, the ejection device for ejecting a fluid includes:
a reservoir comprising a cylindrical body sealably closed at its ends by first and second end portions, said reservoir comprising said fluid,
means for generating a pressurized gas,
a rigid separation means, mobile along the axial direction of said reservoir, localized between the first end portion and said fluid so as to sealably form a first enclosure and a second enclosure containing said fluid, and
communication means for putting the reservoir in communication with said generation means so that the gas generated by said generation means may penetrate into said first enclosure of said reservoir,
an ejection orifice located in the second end portion,
said ejection device including a spring means positioned in said first enclosure of said reservoir so as to exert a compressive force on said separation means along the axial direction of said reservoir, towards the second end portion, regardless of the axial position of the separation means.
Advantageously, the separation means is a heat insulator so as to reduce heat exchanges between said fluid and said generated gas.
Preferably, the separation means comprises a heat insulation area substantially extending along the radial direction of said separation means.
In an embodiment of the invention, as the cylindrical body of said reservoir comprises an inner circumferential shoulder located in proximity to said second end portion, the separation means comprises at least one blocking means exerting a thrust along the radial direction of the reservoir, so that said blocking means expands along the radial direction of the reservoir when said separation means is located facing said shoulder and blocks the displacement or the separation means towards the first end portion of the reservoir.
In another embodiment of the invention, as the separation means comprises at least one communication conduit, the cylindrical body of said reservoir comprises an inner circumferential shoulder in proximity to said second end portion; at least one recess is located in the inner face of the second end portion or in the face of the separation means, so that the generated gas flows up to the ejection orifice when the separation means is substantially located facing said shoulder of the cylindrical body of the reservoir.
Alternatively, the separation means comprises a central portion substantially extending along the diameter of said cylindrical body of the reservoir and a side portion substantially in contact with said cylindrical body, a breakage area extending circumferentially and located between said central portion and said side portion, said second end portion comprises a portion forming an abutment so that under the pressure of said generated gas, said central portion will come into contact with said abutment-forming portion thereby causing breakage of said breakage area of said separation means, so that the generated gas flows up to the injection orifice.
In another embodiment of the invention, a monitoring device is provided including a portion of an electric circuit positioned inside the reservoir so that the electric circuit is open when the separation means is located beyond a determined position towards the second end portion.
Advantageously, a monitoring device is provided including an electric circuit in which at least one electric wire connects said first end portion to said separation means, said wire having a determined length so that there is breakage or disconnection of said wire if the separation means moves beyond a determined position towards the second end portion.
Preferably, the ejection device comprises a distribution cap sealably closing the ejection orifice and distribution means connected to the ejection orifice.
Preferably, the means for generating a pressurized gas include a gas generator comprising an enclosure provided with a gas outlet orifice and a determined amount of gas generating pyrotechnic material.
The present invention also relates to the use of the ejection device including the characteristics which have just been defined, as an emergency hydraulic generator for an aircraft so as to provide hydraulic energy capable of causing mechanical action.
Advantageously, said fluid is an oil.
The invention also proposes according to an other aspect of the invention, a fluid ejection device comprising a number N of reservoirs of said fluid capable of being emptied sequentially. N being equal to or greater than 2, the N reservoirs being connected in parallel to the same circuit for distributing fluid through connections including a cap capable of being torn under the effect of a defined differential pressure, at least N-1 reservoirs include means capable of definitively blocking said connection with the circuit inside the reservoir upon ending the emptying. As the connection with the circuit is blocked upon ending the emptying for each fluid reservoir, it is possible to sequentially trigger the emptying of any other reservoir without any risk that the fluid will fill the already emptied reservoirs instead of being directed towards the points where it is useful, for example towards the fire extinguishing areas. With this multi-reservoir solution, it is possible to have a larger available amount of fluid to be ejected, in smaller reservoirs, therefore more easily integrable in a confined environment, without causing excessive pressure loss in the distribution circuit, because of the absence of valves or gates in said circuit, which also has the advantage of simplifying its installation and maintenance while improving reliability.
Said emptying devices may be of the type—with a membrane—as described in EP1819403, modified so that the means for tearing the membrane upon ending the emptying are suppressed and replaced with a suitable form so that the membrane will fit the orifice of the connection with the distribution circuit and that the latter, under the effect of pressure generated in the reservoir by the gases of the pyrotechnic generator, blocks this orifice. However, said reservoirs advantageously consist of piston devices in which the ejection of the fluid from a reservoir of a substantially cylindrical shape is produced by translational movement of a piston acting on the fluid. The displacement of the piston may be caused by any means known to one skilled in the art, for example via an electric, hydraulic or pneumatic actuator, it may also be produced by the direct action of a magnetic field on the piston or by introducing a pressurized gas behind the piston in a similar way to that of the membrane device. As compared with a membrane device, with such a piston device, it is possible to ensure better emptying of the reservoir, in the fashion of a syringe, but it also simplifies the blocking of the orifice at the end of travel, the face of the piston blocking the orifice of the connection with the distribution circuit either by direct contact or by suitable sealing means.
According to this embodiment, it is absolutely necessary to keep the force applied on the piston or the membrane, via the actuator or the gas pressure at the end of travel so that the latter keep the connection blocked.
According to a more advantageous embodiment, the device includes means for locking the position of the piston at the end of travel. Under these conditions, in order to keep the force blocking the connection to the distribution circuit at the end of travel, it is not necessary to keep the actuators under load or the gas acting on the piston under pressure, which allows improvement in the operating reliability of the device with respect to pressure losses of the devices applying the force on the piston, but also safety of goods and persons after triggering the device thereby avoiding the keeping of pressurized elements, with the risk of explosion and of sudden depressurization which this may incur.
According to a particularly advantageous embodiment, the reservoirs include two chambers separated by the piston, one of the chambers including the fluid to be ejected, the displacement of the piston being caused by gas pressure introduced into the other chamber. As compared with an embodiment in which the displacement of the piston is obtained by the action of a pneumatic, hydraulic or electric actuator, this embodiment is more compact because of the absence of an actuator, and easier to install in a confined environment. The means for generating pressurized gas may be moved away from the installation location of the device which is then connected to these means through suitable pipes, said pipes may be rigid or flexible.
According to a still more advantageous embodiment, the pressurized gas is generated by pyrotechnic means. As said means are very compact, they may be directly installed in each fluid reservoir or in close proximity to the latter. Under these conditions, each fluid reservoir forms a self-contained device, particularly compact and easy to integrate, the triggering means only requiring very little maintenance because of the considerable reduction in the number of components and of mobile parts.
In order to ensure that the whole of the ejected fluid from each reservoir into the distribution circuit actually reaches its point of use with sufficient flow rate, particularly in the case when such a device is used for ejecting a fluid capable of fighting a fire, it is advantageous that the pressurization gases be injected in the distribution circuit upon ending the emptying of each reservoir so as to push the fluid towards its point of use and to completely empty the distribution network. Thus, the device will advantageously include means capable of pressurizing the gas in communication with the distribution circuit upon ending the emptying. These devices may be formed by orifices made on the face of the piston forming a separation between the chambers, said orifices being closed by tared valves so that when there is no longer any fluid pressure exerted on the latter, i.e. upon ending the emptying when the piston is locked, they open in order to let through the pressurized gas towards the orifice for connection with the distribution circuit in order to thereby drive out the fluid. Said valves for example close under the action of a spring when the gas pressure becomes smaller than a determined value.
The springs should be properly weighted in order to prevent the valves from opening too early or not opening. This type of adjustment is however capable of changing over time, for example under the effect of the creep of the materials making up the spring-forming means. Checking and, if necessary, correcting this adjustment, entail complex maintenance operations requiring the opening of the fluid ejection devices. This is why, according to a more advantageous embodiment, the piston includes two sealed areas with the inner surface of the reservoir. Said areas are separated and positioned axially, forming an annular chamber between the piston and the inner face of the reservoir. Blockable communication orifices are placed between said annular chamber and the pressurization chamber, the annular chamber being put into communication with the chamber containing the fluid at the end of travel of the piston. According to this embodiment, the piston includes a skirt. The blockable orifices are transversely located on said skirt and communicate with the annular chamber which is both isolated from the fluid and from the pressurized gas by the two sealed areas during the whole emptying operation. Said orifices are closed by adjusted valves as earlier. When the piston arrives at the end of travel, i.e. upon ending the emptying, and when it is locked, the inner surface of the reservoir comprises a shoulder with larger diameter, so that the first sealed area is no longer in contact with the wall of the reservoir thereby putting the annular chamber comprised between both sealed areas in communication with the chamber containing the fluid (emptied) and the orifice for connection to the distribution circuit. The applied gas pressure on the piston in the other chamber causes opening of the valves blocking the orifices made on the skirt of the piston putting the gas in connection with the annular chamber, therefore with the distribution circuit. When the pressure decreases below a given value, spring-forming means close the blocking valves. This configuration is advantageous since it does not require any specific loading of the valve springs. Indeed, even if the latter open under the effect of the pressure during the emptying, this does not cause any leakage of gas which cannot mix with the fluid, the annular chamber being sealably closed by the two sealed areas. This is particularly important in the case when the ejected fluid is a fluid capable of fighting fire such as a fluoroketone, for example a fluid commercially known under the name of NOVEC® 1230 of the 3M brand. This type of fluid which has very high specific heat would absorb the calories of the pyrotechnic reaction if the gases generated by this reaction would come into contact with it, which would have the consequence of reducing the efficiency of the ejection of the fluid. Thus, by positioning the blockable orifices on the skirt of the piston, which open into a sealed annular chamber, it is possible to avoid any contact of the gases with the fluid ejected during the emptying on the one hand, but also obtain efficient thermal insulation by the front face of the piston between the fluid and the gases.
According to a simpler and more advantageous embodiment, the means for blocking the orifices are formed by an elastic ring. As said elastic ring is positioned in the annular chamber around the skirt of the piston and will by elasticity block the orifices made in this skirt. The characteristics of the ring in terms of material and geometry, are selected so that the latter may be expanded and may thereby open the orifices. This configuration allows simplification of the device for blocking the orifices which may thus be more numerous and promote rapid evacuation of the gases at the end of the emptying so as to ensure high fluid flow rate in the distribution circuit during the whole cycle and thereby limit the pressure losses.
According to a particular embodiment, the elastic ring is formed by a slit ring. This embodiment is particularly economical and reliable, the additional expansion possibilities given by the presence of this slit also facilitating the mounting of the ring. The slit is further used for ensuring the angular position of said ring so that it cannot rotate in its housing and the slit will not be facing an orifice which would cause a loss of the seal.
Such a fluid ejection device may be easily integrated into a confined environment such as the pod of an aircraft engine, since it is compact and easily integrable, it is not under pressure before and after the emptying phase, and may thus be installed as close as possible to the fire sources without generating any risks, notably risks of explosion, for the surrounding installations, and finally, it only requires very limited maintenance. It may therefore be installed in areas which have limited accessibility without causing excessive maintenance costs.
Alternatively, such a device may be used as an emergency hydraulic generation device for an aircraft. With such a device hydraulic energy may be provided, required for operating a mechanical control, for example for applications of the braking type and steering on the ground, or even opening and locking the landing gear. For this type of use, the expelled fluid is hydraulic oil. In this case it is preferable not to promote emptying by expelling the gases into the distribution circuit so as to avoid mixing gases and oil. The presence of several reservoirs in parallel allows several maneuvers to be carried out by triggering the latter sequentially.
Embodiments of the invention will now be described as non-limiting examples with reference to the appended drawings, wherein:
As illustrated schematically in
The reservoir 1 includes one or more ejection orifices 16A, which may be connected to distribution means (not shown) in order to allow ejection of the fluid 14 and its conveyance up to a determined area. The ejection orifices 16A are located in the second end portion 4 of the cylinder and in proximity to this end portion. Advantageously, each ejection orifice 16A is sealably closed by a distribution cap 16 in order to keep the fluid in the reservoir 1 as long as its action is not requested. In particular, if the ejection orifice 16A is a single one, the distribution cap 16 may for example be a tared cap, i.e. a membrane which breaks or opens as soon as the pressure inside the reservoir 1 reaches a certain threshold. The distribution cap may also be advantageously a remote-controlled valve. Other closing devices are for example known from WO 93/25950 or U.S. Pat. No. 4,877,051, and available commercially.
The ejection device according to the invention includes means for generating a pressurized gas. The means for generating a pressurized gas are connected to the reservoir 1 via communication means. Advantageously, the communication means between the reservoir 1 and the means for generating a pressurized gas open into the reservoir 1 oppositely to the ejection orifice 16A, i.e. in the first end portion 3 or in proximity to this end portion. The means for generating a pressurized gas may in a non-illustrated embodiment of the invention consist in one or more reservoirs of pressurized gas. In this case, a valve in the communication means for example allows the pressurized gas reservoir to be isolated from reservoir 1 as long as the latter is not used.
Another embodiment relates to a gas generator 7. Advantageously, for reasons of congestion, and as illustrated in
In the ejection phase, said fluid 14 may absorb a large amount of heat energy from the generated gas. This is notably the case of NOVEC® 1230 marketed by 3M. The heat absorbed by such a fluid 14 causes lowering of the temperature of generated gas, which produces a decrease in the pressure exerted by the gas generated in the reservoir 1 on the fluid 14 to be ejected. This pressure reduction applied to the fluid 14 to be ejected leads to a lower fluid ejection rate 14, which thus reduces the efficiency of the device according to the invention. In order to limit the heat exchanges between both phases, a separation means 5 is required.
The separation means 5 is localized between the first end portion 3 and said fluid 14 so as to sealably form a first enclosure A located between the separation means 5 and the first end portion 3, called a pressurization chamber, on the one hand, and a second enclosure B containing said fluid 14 located between the separation means 5 and the second end portion 4 on the other hand.
The separation means 5 may comprise a central portion 5C substantially extending along the radial direction of the reservoir 1, and a side portion 5L substantially extending along the axial direction of the reservoir 1. The side portion 5L is connected to the central portion 5C at the circumference of the portion 5C. The portions 5C and 5L are rigid. The central portion 5C of the separation means 5 comprises a surface 5A located in the first enclosure A and a surface 5B located in the second enclosure B.
The separation means 5 is mobile along the axial direction of the reservoir 1 so as to have a piston effect: in the ejection phase, the surface 5A is subject to the pressure of the generated gas, a pressure which is imparted to the fluid 14 through the surface 5B of the central portion 5C so as to eject the fluid 14 from the reservoir 1.
Preferably, the separation means 5 is in a thermally insulating material, for example in plastic material, or in any rigid material, covered with an insulating material such as an elastomer. Thus, the fluid 14 cannot absorb the energy of the generated gas, which optimizes the ejection efficiency of the device according to the invention.
The separation means 5 may include seal gaskets or segments 6, placed in circumferential recesses of the side portion 5L facing the inner wall 21 of the cylindrical body 2. With the seal segments 6 rubbing on the inner wall 21 of the cylindrical body 2, any mass transfer may be prevented between the enclosures A and B.
In addition to the advantage of avoiding any heat transfer, the separation means 5 also has the advantage of avoiding any mixing and any dilution of the fluid 14 in the generated gas which would decrease the efficiency of the ejection device. This non-dilution of the fluid 14 in the generated gas is particularly important for certain applications such as extinguishing an engine fire in aeronautics where, for regulatory reasons, a minimum concentration of extinguishing agent should be provided in a relevant fire area during a given period, as described in document EP1552859 filed in the name of the applicant. Indeed, these fire areas are most often ventilated by a significant renewed air flow. Also, it is essential to inject the extinguishing agent as pure as possible into said area very rapidly, in order to obtain the certification criterion by using a minimum amount of extinguishing agent, still with the purpose of minimizing the weight of the extinguisher.
In an embodiment of the invention illustrated in
Thus, any displacement of the separation means 5 because of the volume variation of the volume 14 will modify the volume of the first enclosure A and therefore the prevailing pressure inside this enclosure A. Thus, exposing the first enclosure A to open air via the valve 12 ensures that none of the enclosures A and B of the ejection device according to the invention is pressurized during the out-of-ejection phase.
On the other hand, rapid and large variation of pressure in the first enclosure A because of the generation of pressurized gas is capable of causing the closing of the valve 12.
Thus, by exposing the first enclosure A to open air ensured by the valve 12, it is possible to have in the ejection device according to the invention, pressurized gas during the out-of-ejection phase, and this regardless of the axial position of the separation means 5. Any unnecessary mechanical stress which would make the ejection device fragile is thereby avoided. Further, in the case of a use of the invention on an aircraft, the fact that the internal pressure of the fluid ejection device is always balanced with the outside enables it to be installed as close as possible to the areas to be supplied with fluid 14, while facilitating the response to constraints imposed by aeronautical regulations. With this it is also possible to reduce the length of the distribution conduit connecting the ejection device to the relevant areas. The linear pressure loss in the distribution conduit is therefore reduced with which it is possible to obtain a larger fluid flow rate 14 for a given ejection pressure. The ejection efficiency of the device is thereby improved. Finally, by reducing the length of the distribution conduit and by optimizing the thickness of the walls of the ejection device, it is possible to meet the mass-saving requirements in aeronautics.
With reference to
The valve 12 further comprises a mobile separation means 33 along the axial direction of the valve body 32 and located radially between the valve body 32 and the mobile part 31, said separation means 33 being adapted so as to face said communication conduit 34 of the valve body, so as to block any flow of generated gas through the communication conduit 34, thereby forming a second closure safety device. At rest, the mobile separation means 33 bears against a portion forming an abutment 32B of the valve body 32, under for example the action of a spring 36, compressed between the mobile separation means 33 and the plug 35, so that the separation means 33 is not facing said communication conduit 34.
The mobile part 31 bears upon the mobile separation means 33 via a part forming an abutment 38 interdependent on the mobile part 31, under the action of a compressed spring 37 between the part forming an abutment 38 and the plug 35. It defines a first valve enclosure 30A communicating with the first enclosure A of the reservoir 1 and a second valve enclosure 30B communicating with the outside environment. Both enclosures 30A and 30B communicate with each other via communication conduits 39 located inside the mobile part, comprising an inlet 39A substantially located in the first valve enclosure 30A and an outlet 39B located in the second valve enclosure 30B.
As illustrated in
In order that the valve 12 closes under the pressure of the gas generated in the first enclosure A, the play 40 and the communication conduits 34 and 39 have a size which do not allow inertial flow. With this purpose, a characteristic size of the play 40 and of the conduits 34 and 39 may be of the order of one millimeter.
During the ejection of the fluid under the action of the generated gas, as illustrated in
If a slight leak occurs between the separation means 33 and the body 32 and then towards the conduit 34 of the body 32, as illustrated in
With reference to
In the case of high temperatures, as illustrated in
In the case of low temperatures, the fluid 14 reduces its volume. Because of the pressure exerted by the spring means 13 on the separation means 5, the separation means 5 moves in the direction of the second end portion 4 so as to maintain full and permanent contact between the surface 5B of the central portion 5C of the separation means 5 with the fluid 14 to be ejected. The second enclosure B always has minimum volume.
Thus, because there is permanent contact between the sealed separation means 5 and the fluid to be ejected 14, no mixing occurs between the generated gas and the fluid 14 inside the reservoir 1 during the whole phase for ejecting the fluid 14. Thus, the ejected fluid 14 arrives in the area to be supplied with the fluid 14 with maximum concentration, which increases the efficiency of the ejection device according to the invention. Further, in the absence of any spring means 13, a delay time is present which corresponds to the time during which the separation means 5, when it is no longer in contact with the fluid 14, will come into contact with the fluid 14. By the spring means 13, there is no delay time upon ejecting the fluid 14 since the pressure exerted by the generated gas on the separation means 5 is immediately transmitted through the separation means 5 to the fluid 14 to be ejected. Let us also note that by minimizing the second enclosure B by the separation means 5 on which the spring effect is exerted, it is possible to get rid of any orientation constraint of the ejection device according to the invention. It is no longer necessary to orient the ejection device in the direction of gravity with the ejection orifice 16A at the bottom. Further, the efficiency for ejecting the fluid 14 is improved since the face 5A of the separation means 5 is both subject to the compressive force from the spring means 13 and to the pressure of the generated gas, which increases the ejection rate of the fluid 14 through the ejection orifice 16A.
Within the scope of aeronautic applications, it is advantageous that a monitoring device continuously checks the integrity of a fluid ejection device, notably for an extinguishing application but also for an application as an emergency hydraulic generator.
In an embodiment of the invention, the monitoring device consists of an electric circuit such that the latter changes state between the open state and the closed state, when the separation means 5 is found in a determined axial position between the first end 3 and the second end 4. Advantageously, said electric circuit is open when the separation means is found between said determined position and the second end 4, and closed when it is found between the first end portion 3 and said determined position. This electric circuit consists of two electric conductors, for example electric wires or tracks, positioned on the inner face 21 of the cylindrical body 2 and extending along the axial direction of the reservoir 1. One of the ends of the wires is connected to an electric circuit via a sealed connector 21 located in the first end portion 3. The other end of at least one electric conductor is positioned at a determined distance from the second end portion 4, thereby defining an opening position of the electric circuit. Both conductors are electrically connected through the separation means 5, for example through the blocking means 19 also made in a conducting material. Thus, the separation means 5 ensures closing of the electric circuit when it is located between the first end portion 3 and said opening position, the circuit being open when it is located between said opening position and the second end portion 4. The opening of the circuit will be recognized by a monitoring system as a lack of integrity of the fluid ejection device.
In another embodiment of the invention, the monitoring device 20 is formed by at least one conducting wire 20, preferably two in number, attached to the separation means 5 on the one hand and for example connected to a ground circuit via a sealed connector 21 located on the first end portion 3, as illustrated by
The breakage or the disconnection of at least one conducting wire 20 causes opening of the ground circuit, an opening forming a signal which will be recognized by a monitoring system as a lack of integrity of the fluid ejection device 14 and will cause a maintenance operation during which the problem will be identified rapidly. It is possible to get rid of one of the two wires 20, for example insofar that the ground return is accomplished by the cylindrical body of the reservoir 1, by ensuring electric continuity between the separation means 5 and the cylindrical body 2 for example by using the means 19 for blocking the separation means 5 which will be described in detail later on. As the latter is in contact with the inner wall 21 of the cylindrical body 2 during the displacement of the separation means 5, ground continuity may be ensured.
In the same way as earlier, during the discharge of the ejection device, the separation means 5 by moving, will also rapidly cause the breaking or the disconnection of these wires, and therefore the opening of the ground circuit as illustrated in
In an embodiment of the invention, the separation means 5 is provided with a blocking means 19, as illustrated in
The device may advantageously be used as a so-called “last emergency” hydraulic generation system for an aircraft. In this case, when the aircraft following an incident, has lost all its electric and hydraulic generations, such a device enables hydraulic energy to be provided, required for actuating mechanical control, for example for applications of the braking type, and steering on the ground, or even opening and locking of the landing gear when the characteristics of the gear do not allow these operations to be performed by simple gravity. For this type of use, the expelled fluid is hydraulic oil with suitable characteristics for the relevant application.
The numerical references identical to those of
The piston 5 comprises sealing means with the inner side wall of the reservoir, in the form of an elastic segment 19 and/or a gasket with a lip 6, or a seal segment. The pressurization chamber A is also closed by another end portion 3, or flange, and contains a pyrotechnic gas generator 7. Advantageously the flange 3 closing the pressurization chamber is provided with means forming a valve (not shown) and with which the latter may be put into communication with the open air with regard to slow pressure changes.
Advantageously, the device includes a system for monitoring its integrity, for example as a ground circuit closed by a wire 20 with a determined length, as described earlier. The length of this wire enables it to follow the position changes of the piston over a given range. Such position changes are for example related to heat expansion of the fluid to be ejected. When the device has been triggered or when the level of fluid to be ejected reaches a defined minimum, because of an evaporation phenomenon due to a slight leak towards the outside for example, the wire 20 breaks, opening the ground circuit. It is therefore possible to monitor by a simple electric measurement, taken at the contact 21 located on the upper flange 3, in order to check the integrity of the system, i.e.:
that the ejection device has not been triggered;
that the volume of fluid to be ejected has not passed below a critical threshold which would not allow any longer the device to fully ensure its role of an extinguisher or of hydraulic backup.
As described earlier, the piston is maintained in contact with the fluid to be ejected by means forming a spring acting on the piston along the longitudinal axis of the cylinder. These spring-forming means may be formed with a coil spring with a longitudinal axis (not shown) positioned between the upper flange 3 and the piston 5, or, if the device does not have any means for exposing the pressurization chamber to the open air, they may be formed by the gas initially contained in the latter. According to this embodiment, the pressurization chamber A is sealed off relatively to the outside. Said gas, preferably an inert gas, is introduced therein upon mounting the device under a pressure slightly greater than atmospheric pressure via a valve (not shown) for example located on the upper flange 3. This initial gas pressure in the pressurization chamber is selected so that the piston presses on the fluid to be ejected even if said fluid occupies a minimum volume under the effect of heat expansion and when the maximum pressure in the fluid, when the latter occupies a maximum volume under the effect of heat expansion, is sufficiently far from the pressure causing breakage of the cap, so that there cannot be any risk of breaking the cap except for the triggering case of the device.
According to the invention, the seal between both chambers is improved by the presence of a thimble 50 comprised between the piston 5 and the upper flange 3 in the pressurization chamber A. Advantageously, this thimble consists of a diametrically expandable material, so that it may ensure its sealant role during the pressure rise in the pressurization chamber. In order that the thimble 50 does not prevent the piston from constantly pressing on the fluid to be ejected, the latter consists of a longitudinally extensible material between two extreme positions which the piston may occupy in contact with the fluid to be ejected under the effect of heat expansion of this fluid. According to an advantageous embodiment, the thimble 50 includes at least one fold 51 which facilitates extension thereof.
If an amount of ejection agent is trapped under the thimble 50 over time because of slow degradation of the seal of the gasket 6, this remnant will be pushed back through the seal gasket which is of the type adapted during the emptying phase. A lip gasket is perfectly adapted to this operation.
The combined effects of the rise in pressure in the pressurization chamber A and of the extension until its breaking of the thimble 50, press the thimble against the wall of the pressurization chamber thereby ejecting the fluid remnant through the gasket 6. If the whole agent remnant were not be totally pushed back through the gasket 6, the latter would however be ejected in the fifth phase of the emptying procedure.
The triggering of the discharge of the reservoir is performed by triggering the pyrotechnic gas generator 7. The generation of a gas volume in the pressurization chamber leads to pressure increase in this chamber, a pressure which is transmitted to the fluid to be ejected in the other chamber B via the piston. Under the effect of this pressure, the cap 16 breaks causing flow of the fluid into the distribution circuit and translational movement of the piston, pressed against the fluid by the pressure generated in the pressurization chamber.
The pressure in the pressurization chamber also causes diametrical expansion of the thimble 50.
The translational movement of the piston beyond a defined position causes breaking of the wire 20 and then breaking of the thimble.
At the end of travel, a shoulder 17 made on the wall of the chamber B containing the fluid in the vicinity of the end, allows expansion of the elastic segment 19 of the piston. The expansion of the segment blocks any possibility of upward movement of the piston, and therefore any possibility of upward movement of the fluid in the reservoir.
Advantageously, the piston comprises a valve 60 capable of letting through the gases from the pyrotechnic reaction towards the distribution circuit, in order to purge it.
Numerical references identical to those of
When the pressurized gas fills the chamber A, the membrane 105 deforms towards the chamber B containing the fluid, the pressure increase which results from this in said fluid causes breakage of the tearable cap 16 freeing the orifice for connecting the reservoir to the fluid distribution circuit 25. Thus, the reservoir is put into communication with the distribution circuit 25 and the fluid is poured into the latter towards the point of use.
In order to improve the device as regards these drawbacks, an embodiment of the device according to the invention comprises (
By causing the axial displacement of the piston 5 (
As the orifice 16A of the connection with the distribution circuit is blocked by the piston, there cannot be any return of the fluid into the reservoir already emptied during the subsequent emptying of another reservoir mounted in parallel on the same distribution circuit 25. However, this solution like the previous one (
In order to find a remedy to these drawbacks, an advantageous embodiment (
By elastic reaction, the elastic segment or ring 19 placed in the groove of the piston tends to expand, i.e. to increase its diameter. When during its axial displacement in the reservoir in order to eject the fluid, the piston 5 arrives in the end-of-travel area, the elastic ring 19 moves apart until it reaches the diameter of the shoulder 17. Thus the piston can no longer return backward even in the absence of the application of a mechanical action on the latter.
Under these conditions, even if there is no perfect blocking of the connection with the circuit alone, a small amount of fluid issued from the emptying of another reservoir may penetrate into the emptied reservoir, the piston 5, locked in position by the locking means 17, 19, prevents any filling of the reservoir, via its sealing means with the inner wall of the reservoir 21. Thus, after locking the piston, the volume of the reservoir placed behind the piston, may be purged so that it no longer contains any pressurized gas and thereby avoids any risk inherent to the presence of a pressurized element.
According to an advantageous embodiment (
Ignition of the pyrotechnic cartridge 70 causes generation of pressurized gas which has the effect of propelling the piston towards the other end, thereby compressing the fluid in the chamber B. When the fluid reaches a given pressure, it tears the cap and is poured into the distribution circuit. Upon ending the emptying, the piston is locked by the combined action of the elastic ring 19 and of the shoulder 17, thereby forming an anti-return element in the reservoir.
The reservoir may be equipped with a valve for balancing the pressures 12, for example as described earlier. This particular valve balances the pressure between the inside of the chamber A and the outside of the reservoir in the case of slow variation of said pressure and closes in the case of a pressure peak. Upon igniting the pyrotechnic gas generator 70 or upon introducing a pressurized gas, the sudden change in pressure which results from this in the chamber A closes the valve 12, and propels the piston 5 towards the other end of the reservoir, thereby ejecting the fluid after breakage of the cap 16. Upon ending the emptying, the elastic ring 19 moves apart in the shoulder 17 preventing any return of the piston and thereby forming an anti-return system with respect to the fluid in the distribution circuit. The pressure then stabilizes in the chamber A to a value greater than the pressure outside the body. The balancing valve 12 then allows the gas to escape out of the chamber A and the pressure to be lowered in the latter. Alternatively, the balancing valve 12 may normally be closed and controlled upon opening by a system connecting it to the position of the locked piston 5 at the end of travel, allowing depressurization of the chamber A.
According to this embodiment, a self-contained ejection device is made available which does not remain under pressure after its operation.
However, it is advantageous upon ending the emptying of the reservoir to direct the pressurized gases into the chamber A towards the distribution circuit so as to ensure total emptying of the distribution network.
According to an advantageous embodiment, the axial position of the ring 214 is adjustable in order to ensure perfect support of both ends of the valve 111 on the seats 212, 213. The spring-forming means 112 and the outer diameters of both ends of the valve 111 are selected so that during the emptying, the axial force applied on the valve resulting from the pressure of the gas and which tends to open said valve, is counterbalanced with the sum of the force applied on the other end of the valve by the fluid and of the force of the spring 112, the last two forces tending to close the valve. Thus, as long as there is fluid in the chamber B containing the fluid, the valve is closed and sealed.
When the reservoir is empty, the pressure applied by the gas on the valve 111 is no longer counterbalanced by the pressure of the fluid and the valve opens, letting through the pressurized gas which penetrates into the distribution circuit 25 and promotes ejection of the fluid.
When the pressure in the gas-containing chamber A drops, the valve 111 closes under the effect of the spring 112. As the valve is closed, the piston 5 is again sealed and plays its anti-return role with respect to the fluid contained in the distribution circuit 25.
Advantageously, the valve-forming means 140 (
Valve-forming means 140 are mounted radially and are capable of putting the annular chamber 80 in communication with the chamber A containing the pressurized gas.
During the emptying, both sealing means 121, 122 positioned on either side of the annular groove of the piston are in contact with the inner wall of the cylinder. The pressurized gas tends to open the valve 140, and enters the sealed annular chamber until the pressures counterbalance each other and the valve closes under the action of the spring of the valve.
At the end of travel of the piston, the elastic ring 19 expands in the shoulder 17 preventing the return of the piston 5. Because of the presence of the shoulder 17, the sealing means 122 located in proximity to the front face of the piston 5 is no longer in contact with the wall of the reservoir and no longer ensures its sealing function. Under the effect of the pressure of the gas, the valve 140 opens and puts the pressurized gas in communication with the distribution circuit 25.
According to an alternative embodiment (
Advantageously, the bottom of the reservoir comprises abutment 101 capable of receiving the piston 5 at the end of travel. Upon ending the emptying, the piston will come into contact with said abutment 101 concurrently with the elastic ring 19 blocking the return of the piston by engaging into the shoulder 17. As part of the sealing means 122 is no longer in contact with the inner wall of the reservoir at the shoulder, the chamber 80 is no longer sealed at the end of travel. As the gas pressure continues to expand the ring 116, the gas may flow through the lumens 115 towards the distribution circuit. When the gas pressure drops, the ring 116 is necked down on the lumens again ensuring the seal of the piston and its role of anti-return system with respect to the fluid contained in the distribution circuit.
The elastic ring 116 capable of blocking the lumens 115 advantageously appears as a slit ring (
| Number | Date | Country | Kind |
|---|---|---|---|
| 0758697 | Oct 2007 | FR | national |
| 0801687 | Mar 2008 | FR | national |
| 0805467 | Oct 2008 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP08/64689 | 10/29/2008 | WO | 00 | 4/29/2010 |
