Abstract:
The invention relates to a protection device which defines a through hole ( 21 ) for the passage of a fluid which may be under overpressure conditions. In addition, the inventive device comprises: a stop plug ( 26 ) which can move between an open position and a position in which a first section of the hole ( 21 ) is sealed; a stop valve ( 28 ) which can move between an open position and a position in which a second section of the hole ( 21 ) is sealed; and means ( 22, 23, 27 ) for triggering both the movement of the stop plug ( 26 ) and the movement of the valve ( 28 ) from the open position to the sealing position in response to an overpressure (P 2 ) in the hole ( 21 ). The invention is particularly suitable for self-contained equipment used to supply electrical power by means of a fuel cell.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a protection device for protecting apparatus against overpressure in a fluid feeding the apparatus. The invention also relates to a subassembly including said protection device and enabling a tank for storing hydrogen under pressure to be coupled to a fuel cell forming part of self-contained equipment for supplying electricity. 
     2. Description of the Related Art 
     Fuel cells producing electricity from hydrogen and oxygen can take oxygen from the air of the atmosphere, for example. The hydrogen fed to the fuel cell must come from a source or from a storage tank, from which it is conveyed by a delivery duct. If overpressure should occur in the hydrogen in the delivery duct, then there is a risk of damaging the fuel cell, unless an overpressure protection device has been provided upstream from the cell. 
     U.S. Pat. Nos. 3,424,194 and 3,228,417 disclose associating a pressure regulator with a protection device for providing protection against overpressure at the outlet from the regulator. In those systems, the pressure regulator is provided with a first shutter connected to a first diaphragm, while the protection device is provided with a second shutter connected to a second diaphragm. If overpressure occurs, each of the diaphragms is driven and acts via connection elements to displace each of the shutters towards a position for shutting a through hole. In those systems, two distinct equipment series act respectively on the first shutter and on the second shutter in order to cause them to move towards their respective shut positions, which limits the reactivity of the system against overpressure. Furthermore, such systems are bulky and heavy, which constitutes a drawback when the apparatus that is to be protected against overpressure forms part of equipment that is self-contained and portable.  
     SUMMARY OF THE INVENTION 
     The invention seeks more particularly to remedy those drawbacks by proposing a protection device for protecting apparatus against overpressure in a fluid feeding said apparatus, which device provides the apparatus with protection against overpressure that is effective and reliable, with good reactivity and while occupying little space. 
     To this end, the invention provides a protection device for protecting apparatus against overpressure in a fluid feeding the apparatus, the protection device defining a through hole for passing the fluid and including a shutter movable between an open position and a position for shutting a first segment of the hole, the device being characterized in that it includes a shutter valve member movable between an open position and a position for shutting a second segment of the hole, together with trigger means suitable for triggering both drive of the shutter and drive of the valve member from their open positions towards their shut positions in response to overpressure in the hole. 
     According to other characteristics of the protection device, that are advantageous:
         the trigger means comprise a latch mounted slidably in a bore so as to be movable between a first position in which the latch retains the shutter in its open position, and a second position in which the latch does not oppose the shutter moving from its open position towards its shut position;   it includes a resilient member for returning the latch towards its first position;   the shutter is a slidably-mounted slide, the latch and the shutter sliding respectively in a first direction and in a second direction, which directions intersect and are perpendicular;   the latch separates first and second zones of the bore from each other, and is movable from its first position towards its second position as a function of the  pressure that exists in the first zone that is connected to said hole via at least one connection passage;   the latch cannot be moved from its second position towards its first position until after the first zone of the bore has been purged;   when the shutter is in its open position, but not when the shutter is in its shut position, the shutter retains the valve member in its open position;   the valve member is upstream from the shutter which is slidably mounted to pass from its shut position to its open position while moving towards said valve member and then while pushing said valve member towards its open position;   it includes a bleed passage for purging at least an intermediate segment of the hole when the valve member is in its shut position, but not when the valve member is in its open position, the intermediate segment being located downstream from the valve member;   the shutter is downstream from the valve member and is adapted to open the bleed passage before reaching its shut position;   it includes a connection passage connecting the hole with a chamber defined in part by a member forming part of said trigger means, said connection passage including a second shutter valve member and a resilient member for returning said second valve member upstream towards a position for shutting the connection passage, said resilient return member being calibrated in such a manner as to allow the second valve member to be driven by pressure upstream from the second valve member when said pressure exceeds the pressure downstream from the second valve member by a predetermined quantity;   the chamber is leaktight, the protection device including means for purging said chamber;   it includes means for calibrating the magnitude of the return force exerted by the resilient member on the second valve member;    it includes a state indicator making it possible from outside the body of the device to detect the positions of the shutter and of the valve member; and   said protection device is fitted with one of two complementary male and female portions of a quick coupling so as to enable the hole to be coupled to the other portion of the coupling.       

     The invention also provides a subassembly for coupling a tank for storing hydrogen under pressure to a fuel cell of self-contained equipment for supplying electricity, with the subassembly forming part of said equipment, the subassembly comprising at least one expander for expanding hydrogen under pressure, and a protection device as defined above and placed downstream from the expander so as to be capable of protecting the fuel cell against overpressure of the hydrogen reaching said fuel cell. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be well understood on reading the following description given purely by way of example and made with reference to the accompanying drawings, in which: 
         FIG. 1  is a diagrammatic view of self-contained and portable equipment for supplying electricity from hydrogen stored under pressure in a tank and from atmospheric oxygen, with the help of a fuel cell that a subassembly in accordance with the invention connects to the tank; 
         FIG. 2  is a diagrammatic axial section of a protection device that is in accordance with the invention, that forms part of the coupling subassembly shown in  FIG. 1 , and that can serve to protect the fuel cell from overpressure in the duct for delivering hydrogen to the cell; and 
         FIGS. 3 to 8  are sections analogous to  FIG. 2 , but on a smaller scale, and showing the operation of the protection device shown in  FIG. 2  in the event of overpressure occurring.  
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows self-contained and portable equipment for supplying electricity from hydrogen and oxygen. The hydrogen that is consumed comes from a tank  1  in which it is stored under very high pressure, e.g. at a pressure of the order of 700 bars. 
     In addition to the tank  1 , the equipment shown in  FIG. 1 , comprises a fuel cell  2  that operates in known manner, and a subassembly  3  that connects it to the tank  1 . The subassembly  3  comprises two expanders  4  and  5  in series, together with a protection device  6  for protecting the cell  2  in the event of overpressure occurring downstream from the expanders. By way of example, such overpressure might result from one of the expanders  4  and  5  malfunctioning, which expanders serve to deliver hydrogen at a pressure of a few bars, e.g. at a pressure of the order of  4  bars. The device  6  is thus installed downstream from the expanders  4  and  5 , to which it is connected by a duct  7  of the subassembly  3 . 
     The subassembly also has a male or female portion  8  of a conventional quick coupling enabling the subassembly  3  and the cell  2  to be connected together and to be separated quickly. This coupling portion  8  is fitted to the protection device  6 . The other portion  9  of the quick coupling is fitted to the cell  2 , which is also provided with an intake  10  for atmospheric air. This intake  10  serves to take in atmospheric air, and the cell  2  can subsequently make use of the oxygen therein in order to produce electricity. 
     The protection device  6  is shown on its own in  FIGS. 2 to 8 . It comprises a body  20  that defines a through hole  21 , a connection passage  22 , a variable-volume chamber  23 , a segment  24  of a first bleed passage, and a second bleed passage  25 . Furthermore, the body  20  contains a shutter  26 , a latch  27  for holding the shutter in the open position, a shutter valve member  28  for shutting the hole  21 , a shutter valve member  29  for shutting the connection passage  22 , a shutter valve  member  30  for shutting the bleed passage  25 , and four resilient return members constituted by springs  31  to  34 . 
       FIGS. 2 to 8  are diagrammatic, in particular in that, for reasons of clarity, a portion  20 A of the body  20  is shown therein as being a single part, whereas in reality it is the result of assembling a plurality of parts, some of which are not united until after the members contained inside the body  20  have been put into place. Another portion  20 B of the body  20  is in the form of a hollow screw, having its threaded shank  20 C screwed into a tapped hole in the portion  20 A and defining part of the variable-volume chamber  23 . This portion  20 B has a head  20 D that extends the shank  20 C. An O-ring  20 E contributes to sealing the chamber  23  by being compressed between the portions  20 A and  20 B of the body  20 , in a groove formed in the periphery of the head  20 D. 
     The inlet and the outlet of the hole  21  are designed to be connected respectively to the duct  7  and to the coupling portion  8 . In other words, the hole  21  is designed to pass the hydrogen going from the expanders  4  and  5  towards the cell  2 . Below, and in the accompanying claims, the terms “upstream” and “downstream”, and analogous terms, refer to the direction in which hydrogen flows from the tank  1 , and in particular through the body  20 . 
     Advantageously, the shutter  26  is in the form of a slide that is slidably mounted in the hole  21  so as to be movable along the longitudinal direction X-X′ of the hole  21 . The shutter is pierced by a central longitudinal duct  40  that connects an upstream segment  41  of the hole  21  to a downstream segment  42  of the same hole  21 . Between the segments  41  and  42 , the hole  21  has an intermediate segment  21 A that can be put into communication with the outside via the segment  24  and a hole  56 . More precisely, the hole  56  is a bore in the form of a circular cylinder of axis V-V′.  
     The shutter  26  is provided with two sealing rings  43  and  44 . The ring  43 , i.e. the upstream ring, serves to provide sealing between the wall of the intermediate segment  21 A and the shutter  26  when the shutter is in its open position, i.e. as shown in  FIG. 2 . The ring  44  also serves to provide sealing between the wall of the intermediate segment  21 A and the shutter  26 , but downstream from the ring  43 . 
     The upstream end of the shutter  26  is in the form of a finger  45  for driving the valve member  28  in the upstream direction, and then for holding said valve member  28  in its open position. The valve member  28  is constituted by a ball. The spring  31 , which is then compressed, urges the shutter  26  downstream towards a frustoconical seat  46  defined by the body  20  and situated in the segment  42 , i.e. in a position in which the shutter  26  shuts the hole  21  by bearing against the seat  46 . 
     The shutter  26  has a shoulder  47  enabling the latch  27  to hold it in its open position. The shutter  26  also has a shoulder  26 A. 
     The latch  27  is slidably mounted in a bore  48  so as to be movable along an axis Y-Y′ perpendicular to the axis X-X′, between two positions, in one of which it does not oppose movement of the shutter  26  between its open position and its shut position. In its other position, as shown in  FIG. 2 , and towards which it is urged by the spring  32  that is compressed in the bore  48 , the latch  27  is suitable for holding the shutter  26  in its open position by forming an abutment for the shoulder  47 . 
     Like a piston, a portion  49  of the latch  27  shuts the bore  48  in sealed manner, for which purpose it is provided with an O-ring  50 . This portion  49  defines part of the variable-volume chamber  23 , separating it from a portion V 48  of the volume of the bore  48 , i.e. a portion that is put into communication with the outside via a hole  51  in the body  20  and via a hole  52  in the latch  27 .  
     The passage  22  opens out into the hole  21  downstream from the seat  46 , thereby connecting the hole to the variable-volume chamber  23 . 
     The bleed passage  25  connects the variable-volume chamber  23  to the outside. It is pierced through the portion  20 B of the body  20 . The spring  33  is compressed between the valve members  29  and  30 , urging each of them against a respective seat  53  or  54 , i.e. towards a position in which the connection passage  22  or the bleed passage  25  is shut. The portion  20 B defines the seat  54 . The portion  20 B can be screwed into the portion  20 A to a greater or lesser depth so as to modify the distance between the seats  53  and  54 , i.e. so as to adjust the extent to which the spring  33  is compressed. In other words, because its position is adjustable relative to the portion  20 A, the portion  20 B serves to calibrate, i.e. to set, the magnitude of the force exerted by the spring  33 , in particular on the valve member  29 . The valve member  29  is placed in such a manner that its open position is offset downstream relative to its position shutting the connection passage  22 . The valve member  30  is placed in such a manner that its open position is offset upstream relative to its position shutting the bleed passage  25 . The valve members  29  and  30  are both constituted by balls. 
     The valve member  28  is placed in the hole  21  upstream from the shutter  26  and in line therewith, so as to be movable along the axis X-X′. Its position shutting the hole  21  is offset downstream from its open position. The valve member  28  is urged by the spring  34  towards a seat  55  against which it bears while shutting the upstream segment  41  of the hole  21 . 
     In  FIG. 2 , the protection device  6  allows hydrogen to pass therethrough at a pressure of about four bars. The hydrogen flows through the expanders  4  and  5  towards the cell  2 , as represented by arrows E 1 . By means of its shoulder  47 , the latch  27  acts against the spring  31  to  retain the shutter  26  blocked in its open position, in which position the shutter  26  does not shut the hole  21 , but isolates in leaktight manner the segment  24  from the upstream segment  41  of the hole  21 , i.e. the segment that the duct  40  puts into communication with the downstream segment  42  of the hole  21 . With the shutter  26  in its open position, its finger  45  acts against the spring  34  to retain the valve member  28  in its open position, in which the valve member  28  is spaced apart from the seat  55  and does not shut the hole  21 . Hydrogen from the expanders  4  and  5  flows along the upstream segment  41  of the hole  21 , going round the valve member  28 , and then round the shutter  26  and flowing along the duct  40 , and finally flowing into the downstream segment  42  of the hole  21 . 
     Still in  FIG. 2 , the spring  33  presses the valve member  29  against the seat  53 , such that the connection passage  22  is shut and the variable-volume chamber  23  is isolated from pressure fluctuations that occur in the hole  21 . As a result, the latch  27  remains stationary in spite of these pressure fluctuations and in spite of the fact that only the spring  32  is holding it in its position for retaining the shutter  26 . Having the latch  27  stationary during normal operation of the equipment shown in  FIG. 1  serves to avoid premature wear of the O-ring  50 , and that is advantageous. This leads in particular to the operation of the protection device  6  being very reliable. 
     When the downstream segment  42  of the hole  21  is subjected to overpressure, e.g. because of a malfunction of at least one of the expanders  4  and  5 , i.e. when it is subjected to a pressure P 2  greater than a predetermined threshold above which the cell  2  runs the risk of being damaged and at which the device is set by screwing the portion  20 B into the portion  20 A to a greater or lesser depth, the hydrogen present in the connection passage  22  pushes the valve member  29  towards its open position  against the suitably rated spring  33 , in which position the valve member  29  is spaced apart from the seat  53  and no longer shuts the connection passage  22 . The passage  22  then puts the downstream portion of the hole  21  into communication with the variable-volume chamber  23  which is then brought to the overpressure P 2 , like the hole  21 . This overpressure P 2  exerts thrust on the portion  49  of the latch  27  against the spring  32  that is selected in such a manner that when the pressure in the chamber  23  exceeds the predetermined threshold it causes the latch  27  to slide away from its position for retaining the shutter  26 . 
     Once the latch  27  has been slid away from its retaining position, the protection device  6  is as shown in  FIG. 3 , where the spring  31  pushes the shutter  26  towards its shut position, as represented by arrow F 1 . In parallel, the spring  34  causes the valve member  28  to slide towards its shut position, as represented by arrow F 2 . During the movement of the latch  27 , the chamber  23  increases in volume by filling with hydrogen, with its flow from the hole  21  being represented by arrows E 2 . 
     In  FIG. 4 , the shutter  26  is shown in the middle of sliding under the action of the spring  31 . In other words, it is still not shutting the hole  21 . The same does not apply to the valve member  28 , which is already pressed against its seat  55  by the pressure P 2  upstream therefrom and by the spring  34 . As a result, the downstream portion of the protection device  6  is isolated from the overpressure P 2  in the duct  7 . Still in  FIG. 4 , the shutter  26  continues to isolate the segment  24  from the upstream segment  41  of the hole  21 . 
     In  FIG. 5 , the sliding of the shutter  26  towards the seat  46  continues. Compared with the position of  FIG. 4 , the shutter  26  is nevertheless closer to its shut position. It no longer isolates the segment  24  from the duct  40 , so the duct  40  and the portion of the hole  21  downstream from the valve member  28  are purged, in  particular via said segment  24 , as represented by arrows E 3 . The pressure P 3  downstream from the valve member  28  therefore drops. It is less than the pressure P 2 , so the pressure P 2  can no longer damage the cell  2 , even if it continues to increase. 
     In  FIG. 6 , the spring  31  presses the shutter  26  against the seat  46 . As a result, the shutter  26  shuts the downstream segment  42  of the hole  21 , which segment is also shut by the valve member  28 . In other words, there are two blocks between the duct  7  in which the overpressure P 2  exists and the cell  2 , which cell is therefore very well protected, in compliance with the objects of the invention. The protection of the cell  2  is further improved by the fact that the intermediate segment  21 A and the duct  40  communicate with the outside and are at atmospheric pressure P 0 , even if the shutting performed by the valve member  28  is defective. In addition, in this device, the valve member  28  and the shutter  26  are both driven towards their respective seats as a result of the latch  27  sliding away from its retaining position due to an increase of the pressure in the chamber  23 . Thus, the hole  21  is blocked twice as a result of trigger means that are common both to the valve member  28  and to the shutter  26 . This increases the reactivity of the protection device in the event of overpressure. 
     Still with reference to  FIG. 6 , the variable-volume chamber  23  continues to be subjected to overpressure, i.e. to a pressure such that it prevents the spring  32  from moving the latch  27 . Because of its position, and in particular because of the position of its shoulder  47  along the axis X-X′, the shutter  26  also prevents the latch  27  from reaching its retaining position. 
     When the overpressure upstream from the valve member  28  disappears, the protection device cannot, on its own, return to a flow-passing position, since the springs  31   and  34  continue to hold the shutter  26  and the valve member  28  in their positions for shutting the hole  21 . This also contributes to making the protection device safe, in compliance with the object of the invention. 
     In order to cause the protection device  6  to return to the position of  FIG. 2 , it is necessary for intervention by an authorized person. This person begins by sliding the shutter  26  upstream, as far as its open position, i.e. the position shown in  FIG. 2 . To do this, it is necessary to use a special tool O without which a non-authorized person cannot reset the device  6 . The tool O shown in part in  FIGS. 7 and 8  comprises a body c carrying an off-center drive finger d. The body c is circularly cylindrical in shape, and more precisely it is complementary in shape to the hole  56 . Opposite from the finger d, it has a handle that is not shown. 
     After inserting the finger d in the hole  56  and then along the shoulder  26 A, the authorized person turns the tool O about the axis V-V′, which then coincides with the axis of the body c. The cylindrical wall of the hole  56  then guides the rotary movement of the tool O. During this movement, the finger d presses against the shoulder  26 A and causes the shutter  26  to slide towards its open position, as represented by arrow F 3  in  FIG. 7 . 
     When it is far enough away from the seat  46 , the shutter  26  acts via its finger  45  to move the valve member  28  towards its open position. 
     Once the shutter  26  is in its  FIG. 2  position, it is necessary to purge the variable-volume chamber  23 . To do this, the authorized person moves the valve member  30  away from the seat  54 , e.g. by using a screwdriver T, so that a bleed flow represented by arrows E 4  in  FIG. 8  can be established from said variable-volume chamber  23  towards the outside. At the end of purging, the pressure in the variable-volume chamber  23  is low enough to cease opposing the displacement F 4  of the latch  27  towards its retaining position under drive from the spring  32 .  
     Once the latch  27  has returned into its  FIG. 2  position, the tool O and the screwdriver T can be removed and the protection device  6  is again operational. 
     The device  6  presents a status indicator in that the shutter  26  is provided with an outer peripheral groove  26 B that is painted in a color that is different from the color of the remainder of the shutter  26 . Under drive from the spring  31 , the groove  26 B is brought into register with the segment  24 , and the operator, located outside the body  20 , can detect that the shutter  26  has moved together with the valve member  28  from their open positions as shown in  FIG. 2  towards the positions of  FIGS. 5 and 6 , merely by viewing the groove  26 B through the segment  24 . In a variant, a colored ring could be mounted in the groove  26 B, which would avoid the need for painting it.