Patent Publication Number: US-6336510-B1

Title: Sprinkler device for fire extinguishing systems

Description:
DESCRIPTION 
     The present invention refers to a sprinkler device for fire extinguishing systems. These sprayer devices, also known with the English term “sprinkler”, are usually coupled to a supply line of a pressurized fluid or liquid, typically water, and placed above a predetermined area to be protected against possible damages caused by a fire. 
     Usually the sprinkler device comprises a body made from metal material having an inlet duct and an outlet duct between which a path is delimited for the liquid; the inlet duct is apt to be coupled with the above fluid supply line, whereas a diffuser means integral with the body of the sprinkler device is usually located below the outlet duct, which is apt to sprinkle the liquid with a rainjet over the area to be protected. 
     A shutter is arranged upstream or in correspondence with the outlet duct which, under normal conditions (i.e. in the absence of a fire) hinders the fluid outflow from the sprinkler device. Moreover, room temperature sensing means are associated with the body of the sprinkler device, which are usually directly exposed to the area to be protected; when a predetermined temperature threshold (indicative of a fire) is exceeded, such means cause the shutter to move, so as to let the liquid flow through the outlet duct towards the diffuser underneath, which will then sprinkle the area to be protected. 
     As it can be seen, the above devices are apt to cause the automatic opening of the liquid supply line, in order to obtain the flames extinction, should the room temperature increase to an extent deemed to be excessive; accordingly, it is also clear that the sprinkler devices need to have means for sensing the temperature of the room where they operate, and be able to fastly switch when a predetermined temperature threshold is exceeded. 
     The room temperature sensing means, which as said are also provided for enabling the fluid outflowing from the sprinkler device, may be of various types. 
     Usually, such means consist of a tightly sealed container, such as a glass bulb, containing a material which expand as a function of the temperature of same container; in the instance of a fire, the volume increase of the expansible material, due to a temperature increase of the container, will cause the latter to break out. 
     According to this solution, the container is placed in the sprinkler body to keep a shutter plug in closure of the liquid outlet duct, somewhat like a prop or supporting column; the cracking of the container, caused by the too high room temperature, deprives the plug of its support, which is expelled from the sprinkler body under the pressure of the fluid available in the path, thus releasing the fluid flow. 
     In other known solutions, instead of a glass bulb, sensing elements are provided, which are made from alloys melting at predefined temperatures; in such instances a mechanical kinematic motion is usually provided, which has two portions in a precarious welded to each with a melting alloy, so as to obtain a stable supporting column for the shutter plug; following the melting of the alloy, due to the room temperature being too high, the kinematic motion is released in the sense that the two portions may get free from each other, thus releasing the shutter plug and opening the liquid outlet duct. 
     Though the above solutions are accurate and reliable on an average, they have the drawback of using room temperature means of the disposable type, i.e. which become fully unusable after their first operation, with a consequent need of having to provide for their replacement. 
     Another associated drawback is that the sprinkler devices using the above room temperature sensing means are unable to provide for the automatic resetting of the closed condition of the fluid supply duct, and therefore to stop the fluid supply also when the fire has ceased, with a consequent damages risk due to water flooding. 
     Other known sprinklers have room temperature sensing means which on the contrary actuate a shutter capable of motion from a closed position to an open position of the liquid path; such sprinklers are actuated for their opening by the room temperature increase and back, for then returning to their initial closed condition, as soon as the reasons for operation have ceased, thus avoiding possible damages from flooding. 
     However, such known solutions have the drawback of using a bimetal as a sensing and actuator means, which has a weak force (in the order of a few grams) and a restricted stroke (a few tens of millimeter for small bimetals or anyway a few millimeters for large bimetals, i.e. in the order of a few tens of millimeter) and is not apt to actuate the shutter of the sprinkler device directly; in these instances, the sprinkler device has to be equipped with a complex servo-hydraulic circuit for changing the small bimetal motion in an ample movement of the shutter, whose force is capable of winning the fluid pressure. 
     Other known sprinkler devices provide the use of a motor-driven shutter; in such instances a special electric or electronic control thermostat has to be provided, which is apt to sense room temperature and electrically supply the motor for causing the shutter motion and consequently the opening of the liquid outlet duct, if required. 
     However, also these solutions have some drawbacks, in particular due to their dimensions, manufacturing difficulties and cost. 
     The present invention has the aim of solving the above drawbacks and providing a sprinkler device for fire extinguishing systems which has an improved structure with respect to the known state of the art. 
     Within this frame, an object of the present invention is to provide a sprinkler device having room temperature sensing means, which do not require to be replaced after their first operation, and which are reliable and efficient with time, have restricted dimensions and a low cost. 
     Another object of the present invention is to provide such a sprinkler device which allows for an automatic resetting of the closed condition of the fluid supply duct, after the fire has ceased. 
     These and other objects, as better described in the following, are obtained according to the present invention by a sprinkler device for fire extinguishing systems, having the features of the annexed claims, which form an integral part of the present description. 
    
    
     Further aims, features and advantages of the present invention will become apparent from the following detailed description and the annexed drawings, supplied by way of non limiting example, wherein: 
     FIG. 1 shows a side view of a first possible embodiment of the sprinkler device according to the present invention; 
     FIGS. 2 and 3 show a section view of the device according to the present invention, along the axis A—A of FIG. 1, in two different working positions; 
     FIG. 4 shows a thermal-sensitive element being part of the sprinkler device according to the present invention; 
     FIGS. 5 and 6 show a side view of a second possible embodiment of the sprinkler device according to the present invention, in two different working positions; 
     FIGS. 7 and 8 show a section view of the device according to the present invention, along the axis A—A of FIG.  5  and axis C—C of FIG. 6, respectively; 
     FIGS. 9 and 10 show a section view of a third possible embodiment of the sprinkler device according to the present invention in two different working positions; 
     FIGS. 11 and 12 show a section view of the device according to the present invention, along the axis D—D of FIG.  9  and axis E—E of FIG. 10, respectively; 
     FIGS. 13 and 14 show two orthogonal views of a fourth possible embodiment of the device according to the present invention; 
     FIGS. 15,  16 ,  17  show a section view of the device according to the present invention, along the axis F—F of FIG. 14, in three different working conditions; 
     FIG. 18 shows an enlargement of a portion of FIG. 17; 
     FIG. 19 shows a possible embodiment of the thermal-sensitive element being part of the sprinkler device according to the present invention. 
    
    
     FIGS. 1-3 show a first possible embodiment of a sprinkler device for fire extinguishing systems according to the present invention. 
     Such a sprinkler device, being indicated as a whole with  1 , comprises a body  2  made from metal material, which is hollow inside to delimit a duct with an inlet  3  and an outlet  4 . On its top end, in correspondence with the inlet  3 , the body  2  has an attachment or threaded connector  5 , for its hydraulic connection to a supply line of a pressurized liquid, such as water, not shown in the figures for simplicity&#39;s sake. 
     Reference  6  indicates one of two supporting rods departing from the body  2  on the sides of the outlet  4 , for supporting a distributor  7 ; such a distributor  7  consists of an element having a substantially tapered shape  7 A with its apex directed upwards; segments  7 B depart radially from the base of the element  7 A, slightly biased downwards and spaced between them. As it can be noticed, the apex of the tapered element  7 A is aligned with the outlet  4 ; thus, the liquid flow eventually coming out of the outlet  4  can freely cover the air gap between the rods  6  and reach the element  7 A and segments  7 B, which sprinkle the flow with a rain jet. 
     Reference  8  indicates a shutter inserted in the duct inside the body  2 , where it is guided by a support  9  having a substantially disk shape; the support  9  has a central opening for guide a portion of the shutter  8  and peripheral openings  9 A, to let the fluid flow through. The shutter  8  is of the axial type, i.e. operating along a direction substantially coinciding or parallel to the axis of the fluid conveying duct. 
     The shutter  8  has a plug portion  8 A provided with proper sealing means  8 B, such as an O-ring apt to close up the outlet  4 , and a rod portion  8 C apt for sliding in the central opening of the support  9 . Reference  10  indicates an elastic element, such as a spiral spring, operating between the support  9  and the shutter  8  to maintain, during normal operation, the plug portion  8 A of the shutter in closure of the outlet  4 . Reference  11  indicates a lever, being pivoted in a point  12  on one of the rods  6 . 
     A first end of the lever  11  is directed towards an extension  8 D departing from the lower part of the plug portion BA of the shutter  8 ; the second end of the lever  1  is pointing towards a thermal-sensitive element, indicated as a whole with  13 , which is fixed to a portion  2 A of the body  2 A provided to that purpose. 
     The fixing can be advantageously accomplished through a hole with a female thread in the portion  2 A, and delimiting a male thread on the external surface of the body of the thermal-sensitive element  13 . 
     The thermal-sensitive element  13 , as detailed in FIG. 4, comprises a body or housing  14  made from thermal-conductive material; by way of example, the housing  14  can be made from metal and have a quadrangular section (in particular 6×6 mm) or round section (in particular 8 mm diameter); it can therefore be noticed that the housing  14  is unbreakable also upon attaining high temperatures. The housing  14  has an opening AA on one of its lengthwise ends, and a chamber  15  is delimited inside it, which has for instance a cylindrical section; such a chamber  15  contains a material  16 , which is expansible in temperature, especially a wax. Reference  17  indicates a shaft or thruster, which may be made for instance from stainless steel, partially inserted in the housing  14  through the cited opening; as it will be appreciated, a portion of the thruster  17  is directly embedded in the material  16 , the opposite portion of the shaft exiting the housing  14 . 
     References  18  and  19  indicate two seats, being defined in an area next to the opening of the housing  14  by relevant cylindrical widenings of the chamber  15 ; as it can be seen, the seat  18  more internal to the housing  14  with respect to the opening, has a greater vertical development compared to the seat  19 . In the seat  18  are inserted from the opening AA in the following order: a rigid washer  20  and an elastic gasket or cylindrical bushing  21 ; the washer  20  is preferably made from metal material, such as brass, whereas the bushing  21  is preferably made from PTFE or Teflon® or similar elastic material. 
     On the contrary, a washer  22  preferably made from metal, such as brass, is inserted in the seat  19 , and having a larger diameter compared to the washer  20 ; the lower washer  20  is resting on the shoulder delimited between the seat  18  and the chamber  15 , whereas the upper washer  22  rests on the shoulder delimited between the seat  18  and the seat  19 . 
     Advantageously, the shoulder delimited between the seat  18  and the seat  19  has a flaring like a funnel, whose function is to ease achievement of the relevant seat  18  for components  20  and  21  during the assembly stage; advantageously, too, the upper washer  22  has a dual flaring, i.e. it is beveled along its circumference on both faces. Such a double flaring of the washer  22  does not only ease its insertion inside the opening, but has also the double function of allowing, on one hand, its exact coupling with the flaring of the shoulder defined between the seat  18  and seat  19  and, on the other hand of guiding the deformation of the end of the housing  14  wherein the cited opening is present to make them match exactly together mechanically during the riveting operation. Such end of the housing  14 , is in fact submitted to a riveting operation when manufacturing the element  13 . It will also be appreciated that the double flaring of the washer  22  allows its easy assembly in an automated manufacturing process, since no special orientation for it is required. 
     Therefore, as it can be noticed, the upper washer  22  is housed in a first seat  19  differing from the second seat  18 , wherein at least a radial sealing element  21  operates on the thruster  17 , and wherein also the washer  20  is inserted, so that the washers  20  and  22  delimits a well defined exact housing area ( 18 ,  19 ) for the sealing element  21 ; it is obvious that such sealing means  21  could be more than one and manufactured in different shapes and/or materials. 
     Thus, the above riveting operation of the housing  14  for realizing the closure of the element  13  and then for rusting on the upper washer  22 , will not entail any uncontrolled compression risks on the sealing element represented by the element  21 ; this is just due to the fact Mt the washer  22  and the bushing  21  are housed in two different seats, with the seat of the bushing  18  being more inside the housing  14  and having smaller dimensions compared to the seat  19  of the washer  22 ; this also avoids the risk that the pressure exerted on the washer during the riveting stage of the body  14  may be too high and cause undesired distortions or tears to the bushing. 
     It is obvious, on the other hand that, with the use of sufficiently precise machinery, the element  13  could be manufactured without the shoulder being defined between the seat  18  and the seat  19 , though warranting the operating features described above. 
     Important practical effects tom such a manufacture of the thermal-sensitive element  13 , for the operation of the bushing  21 , are also due to the presence of the lower washer  20 . Such a lower washer  20 , acting as lower supporting means for the bushing  21 , allows an accurate delimitation of the seat wherein the bushing itself should operate, also warranting a large resting surface; finally, the lower washer  20  represents a farther guiding means for the truster  17 . 
     FIG. 4 shows the thermal-sensitive element  13  in its rest position, with the thruster  17  being backward inside the chamber  15 . 
     Following a beat transmission to the housing  14 , an expansion of the expansible material  16  takes place, causing a straight displacement of the thruster  17  outwards (up to the position visible in FIG.  3 ); when heat transmission to the housing  14  decreases or is interrupted, the expansible material  16  shrinks and allow a gradual return of the thruster  17  to its initial rest position, represented in FIG. 3, under the indirect thrust of the spring  10 . It will be appreciated, in particular, that the thermal actuator  13  is apt to exert a thrust of a few tens of kilograms, when covering either strokes or displacements of about 10 millimeters. 
     Back to FIGS. 2 and 3, it can be noticed how the second end of the lever  11  is directed towards the thruster  17  of the thermal-sensitive element  13 , which operates then in a substantially parallel direction to the axis of the sprier device  1 . 
     In FIG. 2 the sprinkler device  1  according to the present invention is represented in its rest position, i.e. in the absence of fire. 
     Under such conditions, the sealing means  8 B of the shutter  8  operate in closure along the circumference of the outlet  4 ; in this way, therefore, the outflow of the liquid being present at the inlet of the body  2  is hindered. 
     It should be noticed that, in general (and independently from the type of embodiment), the sprinkler device according to the present invention is pre-calibrated, i.e. its various components are so assembled to hinder the thermal-sensitive device  13  from operating at a room temperature below a predetermined value, for example 68° C., i.e. maintaining the relevant shutter in closure against a liquid outflow. This means that, during actual use of the device, for instance in a house, the thermal-sensitive device is not apt to cause a fluid outflow unless the room temperature reaches or exceeds a predetermined temperature. It is obvious that various temperature values can be predetermined changing either the type or quantity of expanding material  16 , or changing either the position or the working point of the thermal-sensitive element, for instance screwing or unscrewing more its housing in the relevant threaded seat in the body  2 . 
     In the example illustrated in FIGS. 1-3, this allows to change the relative position between the thermal-sensitive element  13  and the lever  11 , so that a longer or shorter stroke of the thruster  17  is necessary for moving the stopper  8 . 
     Operation of the device shown in FIGS. 1-3 is as follows. 
     When the temperature in the environment gradually starts to increase, such as due to a fire, a gradual temperature increase of the housing  14  of the thermal-sensitive element  13  will take place; such a temperature increase causes the expansible material  16  contained in the thermal-sensitive device  13  to expand, which in turn causes the motion of the thruster  17  out of the housing  14 ; as it can be seen in FIG. 3, such a motion of the thruster  17  causes an angular movement of the lever  11 , which presses the extension  8 D of the shutter  8  and cause the latter to be lifted contrasting the action of the spring  10  and the pressure of the liquid upstream the stopper portion  8 A. Thus, the outlet  4  of the device  1  is made to open up, and the flow of the liquid at the inlet of the body  2  is conveyed to the diffuser  7 , to be rain sprinkled by it on the area to be protected. 
     Afterwards, when the room temperature decreases (for example because the fire in the environment where the device  1  is operating is under control), the housing  14  of the thermosetting element  13  cools down and the material  16  contained in it shrinks; thus, the thruster  17  can go backward, towards its original position, also under the thrust of the spring  10  and shutter  8 , which is able to occlude the outlet  4  again: in this way the liquid flow exiting the device  1  is stopped, The device  1  is therefore of the self-resettable type; it is in fact clear that, if a new fire breaks out, the device  1  is ready again to operate as previously described. 
     FIGS. 5-8, where the reference numbers of the previous figures are partially used to indicate technical equivalent elements, represent a second possible embodiment of the sprinkler device according to the present invention. 
     According to this embodiment, instead of a linear shutter, the sprinkler device  1  has a shutter  30  being spherical and holed, i.e. configured like a pierced ball, which is rotary or angularly movable around an axis being transverse or perpendicular with respect to the axis of the liquid conveying duct in the body  2 . 
     As represented in FIGS. 7 and 8, such a shutter  30  which is housed in the body  2  upstream the outlet  4 , has a central hole  31  and two side extensions  32  and  33 . 
     The extension  32  is inserted in a proper seat defined inside the body  2 , whereas a part of the extension  33  protrudes outside the body  2 , through a central hole of a cover  34 ; such a cover  34  is provided for occluding an opening delimited in the body  2 , for the insertion of the shutter  30  inside the body  2 . 
     On the end of the extension  33  which comes out of the lid  34 , a gear  35  is mounted integral, for engaging a rack kinematics  36 , substantially L-shaped, which is apt to slide on suitable guide means provided on the external surface of the body  2 ; reference  38  indicates an elastic element, such as a spiral spring, for contrasting the motion of the kinematics  36  in one direction (i.e, upwards) and favor it in the other direction (i.e, downwards). 
     The rack kinematics  36  can be linearly moved upwards by the thruster  17  of the thermal-sensitive element  13 , in contrast with the action of the spring  38 , so as to cause an angular movement of the gear  35 , and a consequent rotation of the shutter  30  associated with it; it will be appreciated that also in this embodiment the thermal-sensitive element  13  operates in a direction substantially parallel to the axis of the sprinkler device  1 . 
     In FIGS. 5 and 7, the device  1  is represented in its rest position, where the main hole  31  of the shutter  30  is arranged angularly, i.e. orthogonally to the axis of the duct inside the body  2 , so as to hinder the passage of the liquid to the outlet  4 . Also in this embodiment, when the room temperature starts to increase, such as in case of a fire, the thermal-sensitive element  13  operates as previously described with reference to the embodiment of FIGS. 1-3. The consequent movement of the thruster  17  causes an upwards displacement of the rack kinematics  36 , which caused an angular movement of the gear  15 , and consequently a rotation of the shutter  30  to the position visible in FIG. 8; as it can be noticed, under this circumstances, the hole  31  of the shutter  30  results in being aligned with Me path inside the body  2 , so that the liquid can freely outflow through the outlet  4 , to be sprinkled as previously described. 
     Afterwards, when the room temperature decreases (for instance, because the fire in the environment with the device  1  has been extinguished), the thermal-sensitive element  13  cools down and the thruster  17  goes backward to its original position, under the thrust of the spring  38 ; then the shutter  30  can rotate towards the initial position represented in FIG. 7, for occluding the duct inside the body  2 , and interrupting the liquid flow at the outlet  4 . FIGS. 9-12 represent in several sections another possible embodiment of the sprinkler device according to the present invention; also these figures are partially using the reference numbers of the previous figures to indicate technical equivalent elements. In this instance, the device  1  provides a shutter of a third type, being similar to a slider, indicated as a whole with  40 , i.e. operating along a direction being substantially transverse with respect to the axis of the liquid conveying duct. 
     The shutter  40  has a first lower supporting disk or plate  41  inserted in a suitable seat defined in the duct inside the body  2 , upstream the outlet  4 , and provided with a hole  42 ; a second plate or movable disk  43  rests on such a first plate  41 , which has a hole  44 , whose dimensions substantially match with the hole  42 ; a third upper disk or plate indicated with  45  is inserted in the duct inside the body  2 , above the second plate  43 , which has a hole  46  similar to the hole  42  of the plate  41 . 
     As it can be seen in FIG. 9, boles  42  and  46  of plates  41  and  45  are aligned to each other, whereas in the rest position of the device  1 , the hole  44  of the movable plate  43  is out-of-axis with respect to said holes  42  and  46 , so as to hinder the passage of fluid through the shutter  40 . 
     Plates  41 ,  43  and  45 , for example made from ceramic material, PTFE or Teflon® (or any other material suitable to that purpose, in particular with a hard surface and/or self-lubricating), have well finished surfaces and are placed one on top of the other to ensure a tight seal; such a seal is warranted by a mutual compression between said plates  41 ,  43  and  45  through a spiral spring  47 , working between the upper plate  41  and a stop element  48 , which has a central opening and is made integral with the duct inside the body  2 , 
     An extension  43 A, going through an opening delimited in the body  2 , departs from the movable plate  43 , which ends in a side housing  49 ; an elastic element, such as a spiral spring  50 , is present in the side housing  49 , which reacts the extension  43 A. 
     On the opposite side of the body  2  a seat  51  is provided, for a sealed fastening through a gasket  52  of the thermal-sensitive element  13 ; as it will be appreciated, the thruster  17  of the thermal-sensitive element  13  is inserted in an opening aligned with the resting plane of the movable plate  43 , so as to have a thrust on the latter; therefore, in this instance, the thermal-sensitive device  13  operates in a substantially perpendicular direction with respect to the axis of the sprier device  1 . 
     In the rest condition represented in FIGS. 9 and 11, the hole  44  of the movable plate  43  is out-of-alignment with respect to the holes  42  and  46  of the plates  41  and  45 , so that the duct inside the body  2  is occluded and no liquid can flow towards the outlet  4 . 
     When the thermal-sensitive device  13 , on the contrary, is energized by a room temperature increase as previously described, the movement of the thruster  17  causes the movable plate  43  to move in contrast to the action of the spring  50 . 
     As it can be seen in FIG. 9, following such an actuation, holes  42 ,  44  and  46  are now aligned to each other, thus letting the liquid to pass to the outlet  4  for its rain sprinkling, 
     It is clear, also in this instance, that as soon as room temperature decreases, the thermal-sensitive device  13  cools down, causing a consequent backward movement of the thruster  17  to its original position under the thrust of the spring  50  and the plate  43 , which can go back to its closure position of the duct inside the body  2  as shown in FIGS. 8 and 10, so stopping the liquid flow at the outlet  4 . 
     FIGS. 13-18 represent a further possible embodiment of the sprinkler device according to the present invention; also these figures partially use the reference numbers of the previous figures to indicate technical equivalent elements. 
     In this embodiment, the device  1  comprises a body  2  within which a side chamber  60  is defined; one end of said chamber  60  is closed by a plug  60 A; as it will become apparent later, the chamber  60  is hydraulically connected to the inlet  3  and, through a passage  65 , to the outlet  4 . 
     As it can be seen in FIGS. 15-17, the body  2  has a thermal-sensitive device  13  fastened to it, whose thruster  17  is apt to operate a thrust on one end of a movable slider  62 , the other end of it being reacted by an elastic element  63  housed inside the chamber  60 , such as a spiral spring; the slider  62  has a sealing gasket  64  apt to occlude the internal duct  65  of a shutter  66 , which is movable within the passage  61 . 
     The shutter  66  is integral with one end of a movable membrane  67  (for example manufactured from PTFB or Teflon® or flexible metal sheet), in particular through an elastic ring  68  also acting as a sealing element on the edges  61 A of the passage  61 ; moreover, the shutter  66  is provided with first endings  66 A, which are apt for sliding within the passage  61 ; the endings  66 A are of the cross type, i.e. apt to let the liquid outflow also into said passage when the shutter  66  is in its open position (see for example FIG.  18 ); the shutter  66 , too, has second endings  66 B apt to receive the thrust of the end of the slider  62 , when the latter is motioned by the thruster  17  of the thermal-sensitive device  13  (see for example FIG.  16 ). 
     The membrane  67  has holes  67 A, which let the inlet  3  of the body  1  to communicate with the chamber  60 ; in particular, the total surface of such holes  67 A is smaller than the free surface of the duct  65  inside the stopper  66 . 
     Quite schematically, the operation of the sprinkler device  1  according to FIGS. 13-18 is as follows, bearing in mind that the device  1 , as previously described, is of the normally closed type and, consequently, the position shown in FIG. 15 corresponds to its rest position, i.e. in the absence of a fire. 
     In this condition, the gasket  64  of the slider  62 , being subject to the action of the spring  63 , operates in closure of the duct  65  inside the shutter  66  and the shutter itself operates, through the gasket  68 , in closure of the passage  61 ; the liquid not only fill the inlet  3 , but also the chamber  60  through the holes  67 A of the membrane  67 . 
     Under these conditions, in the chamber  60  a pressure P is determined, which is equal to the pressure P being present at the inlet  3  (FIG.  15 ); such a pressure P inside the chamber is such to thrust on the membrane  67  to maintain the shutter  66  guided by its own endings  66 A, in closure of the passage  61 ; as mentioned above, the shutter  66  seals the edges  61 A through the gasket  68 , so hindering the outflow of the fluid from the inlet  3  to the outlet  4 . When the room temperature gradually starts to increase, for instance due to a fire, a gradual temperature raise of the thermal-sensitive element body  13  is determined; such a temperature increase causes an expansion of the expansible material  16  contained in the thermal-sensitive element  13 , which moves the thruster  17  out of its relevant body  14 ; such a movement of the thruster  17  is translated into a movement of the slider  62  against the action of the spring  63  for the opening of the tankage  65  inside the stopper  66 . 
     Under such an intermediate condition, as represented in FIG. 16, the gasket  64  of the slider  62  operates for the opening of the duct  65  inside the stopper  66 , and the liquid in the chamber  60  outflows through the same duct  65  to the outlet  4 ; it should be appreciated that the liquid which is able to flow from the inlet  3  into the chamber  60 , through the holes  67 A of the membrane  67 , has a restricted flow-rate with respect to the flow-rate admitted through the duct  65 , due to said different sections. 
     Thus, in the chamber  60  a pressure reduction takes place to the value P′ of the outlet  4 , which is commonly at atmospheric pressure (FIG.  16 ). 
     In this situation, the pressure P at the inlet  3  is able to win the pressure P′ in the chamber  60  and start moving, in the opposite direction to the previous one, the membrane  67  and then the shutter  66 ; it should be appreciated that when the end of the slider  62  comes to rest on the endings  66 B, also the thrust of the actuator  13  contributes to motion the shutter  66 . 
     As it can be seen in FIGS. 17 and 18, where the device  1  is represented fully open, the displacement of the shutter  66  releases at this point the passage  61 , wherein to the liquid from the inlet  3  can now outflow sideways the endings  66 A, which have a crosswise section, as said above. 
     The liquid can then reach the outlet  4  and from here flow to the distributor  7  where the flow is widened to fall rain wise on the environment to be protected. 
     It is obvious that afterwards, when the room temperature decreases (for example because the fire in the environment is extinguished ), the thermal-sensitive element  13  cools down and the material  16  contained therein shrinks; this causes the thruster  17  to go backward to its start position, due to the return of the slider  62  subject to a reaction of the spring  63 . 
     Under these conditions, the gasket  64  of the slider  62  operates again for closing the duct  65  inside the shutter  66 , and the pressure of the liquid in the chamber  60  increases up to its original value P, which is equal to the pressure in the inlet  3  and higher than the pressure at the outlet  4 ; such a pressure increase in the chamber  60  therefore causes the membrane  67  to have a movement opposite the previous one; the shutter  66 , integral with the membrane  67 , therefore moves and causes the gasket  68  to seal the edges  61 A of the passage  61 , which is now closed; thus the liquid flow at the outlet  4  is stopped. 
     Operation of the device  1  according to the embodiment of FIGS. 13-18 is typical of a servo-assisted valve type, i.e. using the same pressure of the mains liquid for easing both the opening and closing operations, paired to a direct actuation trough a thermostatic element  13 . 
     In the instance of the application according to the present invention, such a servo-assisted solution is apt to warrant a safe operation of the device  1  also in the presence of high fluid pressures, since the actuator  13  is not required to fully contrast the force exerted by the pressure P on the shutter  66 , but rather only the one exerted on the surface of the slider  62 , which has a smaller amplitude; moreover, the trust produced by the actuator  13  on endings  66 B of the shutter  66  allows for obviating to possible faults, such as a jamming of the shutter itself, due to scaling or many years of inactivity; under such irregular conditions, a bimetal would not be enough to cause the opening for the liquid to flow through. 
     It should be noticed that thermal-sensitive elements  13  having also an actuator function of the type as provided by the present invention, are of simple and cheap manufacturing and apt to develop a considerable power in relationship to their small dimensions. 
     As a result, the overall dimensions of the thermal-sensitive/actuator element can be reduced, though obtaining an equal or higher power that can be developed by it with respect to the commonly known solutions, with an excellent reliability and fast and accurate operation; this also entails the possibility of obtaining sprinkler devices  1  with smaller overall dimensions than those provided by the known state of the art. 
     It should also be appreciated that according to the examples of the present invention described above, the motion of the thruster  17  is directly caused by the expansion of the expansible material  16 , i e. such a motion is not “averaged” by any isolating means between the two elements, such as a rubber membrane; the element  13  differs from the thermal actuators commonly known and used in thermostatic valves for sanitary use, which require an insulating membrane between the expansion chamber of the expansible material and the thruster; such a membrane used in the known applications is commonly obtained from elastic materials, which are not suitable for operation at temperatures over 100° C. On the contrary, the thermal-sensitive element  13  can also operate at temperatures over 200° C., through the use of the bushing  21  made from PTFE or Teflon®. 
     According to the above, it will be apparent how the object of the present invention represents an improvement with respect to the present state of the art. 
     With regard to commonly known solutions using breakable bulbs or melting alloys, the sprinkler device  1  according to the present invention has the advantage of having room temperature sensing means, which do not necessarily need to be replaced after their first operation. 
     Another advantage of the sprinkler device  1  according to the present invention is that it can also be manufactured as a self-resettable device. 
     Compared to the known solutions using bimetal elements, the sprinkler device  1  according to the present invention develops a considerable power, apt to reduce a jamming risk for the shutter due to scaling or many years of inactivity, in spite of the very small size of its thermal-sensitive element  13 . 
     An associated advantage is represented by the fact that the use of the thermal-sensitive device  13  allows for providing for the device  1  a large number of technical solutions for shutting purposes, in spite of its reduced dimensions and low cost; as previously described, in fact, it is possible to provide shutters with axial, angular or perpendicular motion with respect to the direction of the flow to be stopped or shutting systems which use the same pressure of the liquid for facilitating both the opening and closing operations of the device. According to the above description, the features of the sprinkler device for fire extinguishing systems provided by the present invention are clear, as well as also its advantages are clear. 
     It is obvious that many changes are possible for the man skilled in the art to the sprinkler device for fire extinguishing systems described by way of example, without departing from the invention, and it is also clear that in practical actuation of the present invention the components described may have a different shape and material and be replaced by technical equivalent elements. 
     For instance, the thermal-sensitive element  13  may be manufactured using several sealing elements for the closure of the housing  14 . Similarly the bushing  21 , due to the fact that it is subject to distortions for matching with the surrounding surfaces and/or free spaces, may have a different configuration from the one shown by way of example. 
     With reference to the embodiment of FIGS. 1-3, several thermal-sensitive elements  13  can be provided in parallel, in order to increase the available power for winning the contrary thrust of the pressurized fluid, which is the higher the more the shutter surface is wider. 
     With reference to the embodiment of FIGS. 13-18, the passage  61  and all components associated to it, such as the actuator  13 , the slider  62 , the membrane  67 , etc., may be angularly oriented with respect to the inlet  3  (for example 45° instead of 90°), so as to reduce the tortuosity of the fluid path. 
     A further possible change relates to the manufacture of the thermal-sensitive element, which could be similar to the one represented in FIG.  19 . 
     Such a thermosetting element indicated with  105  has a body  105 A, delimiting a chamber containing an expansible material indicated with  105 B, which in this case is a fluid such as a special alcohol or solvent; 
     The body  105 A has a lengthwise opening, which is closed by a washer  105 G made from rigid material; a metal sealing bellows  105 H closed on one end is fixed in correspondence of the central hole of the washer  105 G, which extends towards the chamber inside containing the fluid  105 B; finally, the thruster of the thermal-sensitive element is indicated with  106 , which is partially inserted in the bellows  105 H through the central hole of the washer  105 G. 
     As to the assembly of the element  105 , the bellows  105 H is fastened to the central hole of the washer  105 G, such a coupling between the components being ensured by welding, brazing, tinning or a similar procedure. It should also be noticed that the washer  105 G, has a shaping near its edge on one of its faces, and the bellows  105 H extends from the opposite face of said washer. 
     The washer  105 G is then placed in correspondence with the lengthwise opening of the body  105 A and the latter is mechanically riveted, i.e. folded on the washer itself; also in this instance, in order to warrant a safe sealed closure, the washer  105 G is sealed to the body  105 A in correspondence of its own shaping, for example by welding, brazing, tinning, etc. 
     Then the bellows  105 H is properly pre-tensioned towards the inside of the body  105 A, and the latter is filled with fluid  105 B; the fluid is introduced in the body  105 A through a suitable opening, not shown in the figure, which at the end of the operation is closed by a small ball. Finally, a portion of the thruster  106  is inserted in the bellows  105 H, through the central hole of the washer  105 G. 
     Operation of the thermal-sensitive element  105  is similar as previously described with reference to the thermal-sensitive element  13 . In particular, a temperature increase in the environment determines a temperature raising of the body  105 A and such a temperature increase cause expansion of the expansible fluid  105 B; the expansion of the fluid is discharged on the bellows  105 H, which is gradually compressed towards the washer  105 G, causing a motion of the thruster  106  for exiting the body  105 A. 
     Afterwards, when the room temperature decreases, the body  105 A cools down and the fluid contained in it shrinks; this allows a backward movement of the thruster  106  and bellows  105 H to their starting positions, respectively, also due to the action of the elastic elements provided by the sprinkler device where the thermal-sensitive element is used, and to the vacuum existing in the body  105 A. 
     It should be noticed that the thermal-sensitive element  105  represented in FIG. 19 does not require any rubber gasket or in other temperature degradable material; by this particular embodiment, moreover, a temperature sensing element could be provided, being remote with respect to the thermal-sensitive element  105 , and connected to it through a capillary flexible metal tube. 
     Other possible embodiments provide thermal insulating means between the housing  14  or  105 A of the thermal-sensitive element  13  or  105  and the body  2  of the sprinkler device  1 , in order to avoid heat dissipation from said housing to said body; such means may consist of a bushing in suitable insulating material, made integral with the body  2 , wherein the housing  14  or  105 A would be fastened. 
     Finally, it is clear that due to the high power of the thermal-sensitive element  13 , many other types of shutter can be advantageously used on the sprinkler device according to the present invention, with restricted overall dimensions.