CA1138298A - Safety closure device - Google Patents
Safety closure deviceInfo
- Publication number
- CA1138298A CA1138298A CA000326681A CA326681A CA1138298A CA 1138298 A CA1138298 A CA 1138298A CA 000326681 A CA000326681 A CA 000326681A CA 326681 A CA326681 A CA 326681A CA 1138298 A CA1138298 A CA 1138298A
- Authority
- CA
- Canada
- Prior art keywords
- piston
- conduit
- fluid
- section
- parts
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K17/00—Safety valves; Equalising valves, e.g. pressure relief valves
- F16K17/20—Excess-flow valves
- F16K17/22—Excess-flow valves actuated by the difference of pressure between two places in the flow line
- F16K17/24—Excess-flow valves actuated by the difference of pressure between two places in the flow line acting directly on the cutting-off member
- F16K17/28—Excess-flow valves actuated by the difference of pressure between two places in the flow line acting directly on the cutting-off member operating in one direction only
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Actuator (AREA)
- Infusion, Injection, And Reservoir Apparatuses (AREA)
- Control Of Fluid Pressure (AREA)
- Safety Valves (AREA)
- Sliding Valves (AREA)
- Measuring Fluid Pressure (AREA)
- Pipe Accessories (AREA)
Abstract
ABSTRACT.
A safety closure device is described for use in a distribution system for fluid under pressure. The device comprises a conduit adapted to be inserted into the system and a piston displaceable relative to the conduit capable, in an end position, of closing off flow through the conduit and, in another positon of providing a flow duct for fluid. Means are provided for adjusting the flow duct section to establish a normal fluid pressure difference upstream and downstream of the piston and for maintaining this equilibrium to a threshold value of the difference.
Exceeding the threshold value causes displacement of the piston to close the conduit.
A safety closure device is described for use in a distribution system for fluid under pressure. The device comprises a conduit adapted to be inserted into the system and a piston displaceable relative to the conduit capable, in an end position, of closing off flow through the conduit and, in another positon of providing a flow duct for fluid. Means are provided for adjusting the flow duct section to establish a normal fluid pressure difference upstream and downstream of the piston and for maintaining this equilibrium to a threshold value of the difference.
Exceeding the threshold value causes displacement of the piston to close the conduit.
Description
_ELD OF INVENTION - ll~Z~8 The present invention relates to a safety closure or shutoff device suitable for a circuit or distribution system for fluid under pressure, comprisiny a pipe adapted to be inserted into the circuit or distribution system, a piston displaceable relatively to the pipe and so arranged as to close off a flow section for fluid through the pipe when it is in one of its end positions and to provide a flow duct for the fluid in another of its positions.
BACKGROUND OF THE INVENTION
Safety closure devices are already known which can be used for shutting off a pipe for gas under pressure, in which the piston is actuated by the shock wave produced by an explosion upstream of the device. Such a device is designed so as to react to a sudden and very considerable increase in the pres~ure and generally comprises special means which have to ensure the closure at these high pressures, this involving a size and a construction which do not permit the device to be used for other applications.
OBJECT OF THE INVENTION
The present invention seeks to provide a device adapted to be incorporated into a circuit or a supply or distribution system for fluid of different types, for example, in a hydraulic control circuit, such as a control circuit for - ~138Z98 hyclraulic brakes or jacks, or a distribution system for a compressed gas or a vapour under pressure, or even for a liquid, such as water or petroleum, without having any effect on the normal functioning of such a circuit or distribution system, but permitting an undesired flow of the fluid to be prevented in the event of the distribution system or piping breaking in the part situated downstream of the device or in the event of another phenomenon leading to an undesirable pressure drop downstream of the device.
SUMMARY OF THE INVENTION
According to the invention there is provided a safety closure or shut-off device suitable for a distribution s~stem for fluid under pressure, comprising a conduit adapted to be inserted in the said system, a piston displaceable in a piston chamber forming part of the said conduit, at least one flow passageway of adjustable section being provided through the piston, an outlet orifice of the piston chamber being arranged to be closed by the piston when the piston is in one of its end positions in the piston chamber, the difference of fluid pressure between the upstream and downstream sides of the piston tending to push the piston towards said end position, the displaceme~t of the piston being hindered by the sliding resistance of the piston, means for adjusting the section of the flow passageway independently from the 1~38Z9B
- 3a -position of the piston in the conduit so as to make it possible to adjust the value of the pressure difference bet:ween the upstream and downstream sides of the piston in such a manner that, up to a given maximum flow rate, the force acting to push the piston towards the position for shutting off the conduit is less than the force needed to overcome the sliding resistance, so that the piston remains immobilized in a position allowing the fluid to pass through the conduit, whereas an increase of the said pressure difference over a threshold value causes a displacement of the piston to the position for completely shutting off the conduit.
According to one preferred embodiment, the piston comprises two parts, which are displaceable relatively to lS one another for forming a flow duct of adjustable section.
More particularly, the said parts of the piston may be traversed by an orifice forming at least a part of the flow duct, the relative 1~38298 displacement of the two parts of the piston permitting the section of this orifice to be regulated. The closure device according to the invention may comprise piston-restraining means, these being in the form of mechanical, hydraulic, pneumatic, magnetic and/or electromagnetic means. The said means may be arranged for automatically adapting the res-training force to variationsin pressure upstream of the piston and/or may be adjustable from outside the pipe of the device.
The device according to the invention may comprise a mechanical member, such as a rotatable rod, extending through the wall of the pipe, the said member being coupled to one of the adjustement of the section of the flow duct. According to one embodiment, an actuating element extends through a lateral openlng in the pipe and ls fast with an ad~usting member ar-ranged for assuring the tight closure of the said opening in the pipe.
According to a modified form of the invention, the piston may be controlled by means of a rod passing through the wall of the pipe, by a flexible membrane or diaphragm fixed to the rod and mounted inside a chamber integral with the pipe.
Hydraulic or pneumatic means may be provided for acting on the diaphragm so as to control the restraining force of the piston and/or so as to actuate the latter under the effect of an external control for shutting off the distribution system.
::: ::
i BRIEF DES~RIPTION OF THE DR~WINGS
~ ~' ~` - 4 -Various embodiments of the invention will now be described by way of example with reference to the drawings, wherein :
Figures 1 and 2 show a first embodiment o~ the device according to the invention, Figure 1 being a section along a plane of symmetry passing through the axis of the piston and Figure 2 being a section on the line II-II of Figure 1 ;
Figures 3 and 5 re~resent a second embodiment of the device according to the invention, Figure 3 being a section on the line III-III of Figure 4 and Figures 4 and 5 being respectively sections of the device along the lines IV-IV and V-V of Figure 3 ;
Figures 6 to 9 are diagrammatic views in axial section of other forms and modifications of the device according to the invention ;
Figures 10 to 12 also represent another modified form, Figure 10 being a longitudinal sectional view of the device, Figure 11 a section on the line II'-II' of Figure 10 and Figure 12 a section on the line III'-III'of Figure 10.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
.
Referring to the drawings the device which is shown in Figures 1 and 2 comprises a housing 1 having an inlet connection part 11 and an outlet connection part 12, each having a screw thread for enabling the safety device to be incorpora~ed into a distributlon system, ~38Z9~3 for example, into the water supply pipe of a washing machine.
The hollow housing 1 comprises essentially three chambers, namely, an inlet chamber 13, a piston chamber 14 and an outlet chamber 15. The piston ch~mber 14 is formed by a tu-bular sleeve 2 mounted in a corresponding hollow portion ofthe housing 1 and having openings for the inlet and outlet of fluid, such openings being respectively indicated at 21 and 22. By means of these openings, the piston chamber 14 commu-nicates respectively with the inlet and outlet chambers which, at their other ends, open on to the corresponding connection parts. A piston 3, arranged inside the sleeve 2 so as to be axially displaceable, comprises two juxtaposed parts 31 and 32, through which extend openings 33 and 34, respectively.
Th~ shane of these openings in shown by way of example in Figure 2. It is so chosen as to permlt the rate oE flow of fluld through the device to be regulated by a relative rota-tion between the two parts of the piston. For this purpose, the part 32 is fast with a regulating rod 4 which extends through a bore in the part 31 and also the part of the hous-ing 1 facing the sleeve 2 through a plug 5 screwed into the :~ housing 1. The part 31 has on its periphery a cam 35 which is engaged in a longitudinal groove 23 of~the sleeve 2 and .
- prevents the rotation of the part 31 relatively to the said sleeye. In the axial direction, the part.s 31 and 32 are displa-ced together, the rod 4 being designed to carry a fixing ele-ment, such a.s a spring ring 41, facing the part 31.
At its free end, the rod 4 comprises an adjusting knob
BACKGROUND OF THE INVENTION
Safety closure devices are already known which can be used for shutting off a pipe for gas under pressure, in which the piston is actuated by the shock wave produced by an explosion upstream of the device. Such a device is designed so as to react to a sudden and very considerable increase in the pres~ure and generally comprises special means which have to ensure the closure at these high pressures, this involving a size and a construction which do not permit the device to be used for other applications.
OBJECT OF THE INVENTION
The present invention seeks to provide a device adapted to be incorporated into a circuit or a supply or distribution system for fluid of different types, for example, in a hydraulic control circuit, such as a control circuit for - ~138Z98 hyclraulic brakes or jacks, or a distribution system for a compressed gas or a vapour under pressure, or even for a liquid, such as water or petroleum, without having any effect on the normal functioning of such a circuit or distribution system, but permitting an undesired flow of the fluid to be prevented in the event of the distribution system or piping breaking in the part situated downstream of the device or in the event of another phenomenon leading to an undesirable pressure drop downstream of the device.
SUMMARY OF THE INVENTION
According to the invention there is provided a safety closure or shut-off device suitable for a distribution s~stem for fluid under pressure, comprising a conduit adapted to be inserted in the said system, a piston displaceable in a piston chamber forming part of the said conduit, at least one flow passageway of adjustable section being provided through the piston, an outlet orifice of the piston chamber being arranged to be closed by the piston when the piston is in one of its end positions in the piston chamber, the difference of fluid pressure between the upstream and downstream sides of the piston tending to push the piston towards said end position, the displaceme~t of the piston being hindered by the sliding resistance of the piston, means for adjusting the section of the flow passageway independently from the 1~38Z9B
- 3a -position of the piston in the conduit so as to make it possible to adjust the value of the pressure difference bet:ween the upstream and downstream sides of the piston in such a manner that, up to a given maximum flow rate, the force acting to push the piston towards the position for shutting off the conduit is less than the force needed to overcome the sliding resistance, so that the piston remains immobilized in a position allowing the fluid to pass through the conduit, whereas an increase of the said pressure difference over a threshold value causes a displacement of the piston to the position for completely shutting off the conduit.
According to one preferred embodiment, the piston comprises two parts, which are displaceable relatively to lS one another for forming a flow duct of adjustable section.
More particularly, the said parts of the piston may be traversed by an orifice forming at least a part of the flow duct, the relative 1~38298 displacement of the two parts of the piston permitting the section of this orifice to be regulated. The closure device according to the invention may comprise piston-restraining means, these being in the form of mechanical, hydraulic, pneumatic, magnetic and/or electromagnetic means. The said means may be arranged for automatically adapting the res-training force to variationsin pressure upstream of the piston and/or may be adjustable from outside the pipe of the device.
The device according to the invention may comprise a mechanical member, such as a rotatable rod, extending through the wall of the pipe, the said member being coupled to one of the adjustement of the section of the flow duct. According to one embodiment, an actuating element extends through a lateral openlng in the pipe and ls fast with an ad~usting member ar-ranged for assuring the tight closure of the said opening in the pipe.
According to a modified form of the invention, the piston may be controlled by means of a rod passing through the wall of the pipe, by a flexible membrane or diaphragm fixed to the rod and mounted inside a chamber integral with the pipe.
Hydraulic or pneumatic means may be provided for acting on the diaphragm so as to control the restraining force of the piston and/or so as to actuate the latter under the effect of an external control for shutting off the distribution system.
::: ::
i BRIEF DES~RIPTION OF THE DR~WINGS
~ ~' ~` - 4 -Various embodiments of the invention will now be described by way of example with reference to the drawings, wherein :
Figures 1 and 2 show a first embodiment o~ the device according to the invention, Figure 1 being a section along a plane of symmetry passing through the axis of the piston and Figure 2 being a section on the line II-II of Figure 1 ;
Figures 3 and 5 re~resent a second embodiment of the device according to the invention, Figure 3 being a section on the line III-III of Figure 4 and Figures 4 and 5 being respectively sections of the device along the lines IV-IV and V-V of Figure 3 ;
Figures 6 to 9 are diagrammatic views in axial section of other forms and modifications of the device according to the invention ;
Figures 10 to 12 also represent another modified form, Figure 10 being a longitudinal sectional view of the device, Figure 11 a section on the line II'-II' of Figure 10 and Figure 12 a section on the line III'-III'of Figure 10.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
.
Referring to the drawings the device which is shown in Figures 1 and 2 comprises a housing 1 having an inlet connection part 11 and an outlet connection part 12, each having a screw thread for enabling the safety device to be incorpora~ed into a distributlon system, ~38Z9~3 for example, into the water supply pipe of a washing machine.
The hollow housing 1 comprises essentially three chambers, namely, an inlet chamber 13, a piston chamber 14 and an outlet chamber 15. The piston ch~mber 14 is formed by a tu-bular sleeve 2 mounted in a corresponding hollow portion ofthe housing 1 and having openings for the inlet and outlet of fluid, such openings being respectively indicated at 21 and 22. By means of these openings, the piston chamber 14 commu-nicates respectively with the inlet and outlet chambers which, at their other ends, open on to the corresponding connection parts. A piston 3, arranged inside the sleeve 2 so as to be axially displaceable, comprises two juxtaposed parts 31 and 32, through which extend openings 33 and 34, respectively.
Th~ shane of these openings in shown by way of example in Figure 2. It is so chosen as to permlt the rate oE flow of fluld through the device to be regulated by a relative rota-tion between the two parts of the piston. For this purpose, the part 32 is fast with a regulating rod 4 which extends through a bore in the part 31 and also the part of the hous-ing 1 facing the sleeve 2 through a plug 5 screwed into the :~ housing 1. The part 31 has on its periphery a cam 35 which is engaged in a longitudinal groove 23 of~the sleeve 2 and .
- prevents the rotation of the part 31 relatively to the said sleeye. In the axial direction, the part.s 31 and 32 are displa-ced together, the rod 4 being designed to carry a fixing ele-ment, such a.s a spring ring 41, facing the part 31.
At its free end, the rod 4 comprises an adjusting knob
2 8 42 which, firstly, permits a certain angular di.splacement to be :1~38Z98 imposed on the part 32 of the piston relatvely to the part 31 and, secondly, the displacement of the piston assembly in an axial direction. At the point where the rod 4 passes through the~ plug 5, a lipped packing 6 is disposed in the plug and extends around the rod 4. The tightness at the periphery of the plug 5 is assured by an annular packing 7. On the downstream side of the piston, the part 32 of the latter has a conical portion which is adapted progressively to close the outlet opening of the sleeve 2 when the piston is displaced in the direction of flow of fluid. The outlet opening of chamber 14 is additionally formed by the central opening of an annular packing 8, which ensures a tight closure of the fluid duct in the final position of the piston at the time of its axial displacement for closing purposes. When the present safety dev~ce ls fitted lnto a fluid clrcult havlng a maximum rate of flow determined downstream of the device, the rate of flow through the duct 33,34 of the piston is regulated by means of the knob 42 as a function of this maximal flow. This adjustment is effected particularly in such a way that the piston remains in equilibrium in the fluid flow, despite the pressure drop through the duct 33,34 and the possible leakages of liquid at the periphery of the piston, this latter not necessarily being tight.
The surface of the piston exposed to the fluid pressu-re upstream of the piston is reduced, relatively to the piston surface on the downstream side of the latter, by the section 27 of the rod 4, which represents a not inconsiderable fraction 1~38Z98 of the total section of the piston. The adjustment of the sec-tion of the duct 33,34 thus makes it possible, even without other piston-restraining means, to achieve the equilibrium of said piston for a given maximum rate of flow. If it should happen that the pressure downstream of the piston falls sudden-ly, for example, as a consequence of the pipe breaking, the piston is displaced in the direction of the flow and comes to a position closing the opening 22. The pipe is thus closed automatically in such a case and may be opened again when the permitted maximum rate of flow is re-established. The piston is then placed by means of the knob 42 in an axial position per-mitting the passage of the liquid, by the rate of flow through the flow passage of the piston being regulated again as requi-red.
A supplementary means for retalnlng the plston in its posltion of equilibrium isformed by the lipped packing 6.
As the action of this packing on the rod 4 is reinforced when the pressure of the fluid flow upstream of the piston increases, the presence of this packing not only makes possible a shift in the adjustment range of the triggering threshold of the sa-fety device, but also an avoidance of an inopportune actua-tion of the said safety device, following an increase in the pressure upstream of the piston, i.e. in the entry chamber 13.
Other piston-restraining means may be used for replacing the means mentioned above or for complementing these latter.
It is in particular possible to prov~de a second lipped packing 27 on the periphery of the piston, so as to increase the restrai-ning force ~lth a sudden increase in the entry pressure. Accor-ding to a modified embodiment, the rod 4 may be of very small section and be provided with a mechanical means, for example a spring, a magnetic means, an electromagnetic means or a S hydraulic means for obtaining a restraining force on the pis-ton, which force may either be constant or variable. More par-ticulary, adjustment means may be provided for adapting the safety device to different cases of application or different operating conditions.
Figures 3 to 5 show one constructional form of the safety device, in which the piston and the means for adjusting the section of the flow duct are coaxially arranged. This device comprises a conduit formed by two coaxial parts, 51,52 which are formed t their froe ends with means, for example a screw thread, for permitting the device to be fitted lnto a fluid distrlbution system or pipeline. On lts other end, the part 51 is terminated by tw~ slde members 51' and 51" ,which extend the wall of the condui 51 in two diametrically opposite regions and form beuween them 1wo lateral openings of the pipe or conduit of the device At their free ends, the parts 51', 51"
are of a reduced thickness, so that the external diameter which they define correspondj to that of a tubular sleeve 53~formed with two diametrically opposite notches, into which are fit-ted the ends of the parts 51',51". The external surface of the sleeve j3 and of the ends Sl',Sl" are formed with a screw thread corresponding to an lnternal screw thread of the conduit 27 part 52, th IS making p~ssible the screwing of the part ~-2 on to the end of the assembly 51,53.
The pistorl of the device according to Figure 3 to 5 is rormed by two parts 60,62 of which the first has a coni-cal portion co-operating with an annular packing 54 fitted Ln the member 51. The central portion of the member 60 has extending therethrough two openings 61,61', which represent the flow duct through the piston. As the part 62 of the piston essentially has the form of a disc in which are drilled two openings permitting the passage of the slide members 51'and 51", it has in its central portior openings 63,63' of the same shape as the openings 61,61'. The part 62, guided by the side members 51',51", may only be displaced axially, whereas the part 60, connected to ~2 by means of a screw 64, can be shifted angularly in relation to 62. Thus, as shown in Flgure 5, the openings 61,63 and 61',63' can be offset from one another in order tc define th~ section of the flow duct through the device. In order to permit this adjustment, the part 60 has two latera] arms extending through the lateral openings formed in the pipe or corduit 51 between the side members 51' and 51", the ends of these arms being fitted into a casing formed of two parts 55,56, the internal dia-meter of which corresponds to the external diameter of the part 62. The two parts 55 and 56 can be screwed into one another, an annular packing 57 en uring the tightness of the assembly at this pcsition. Each part of the casing has an axial bore of a diameter sli~3htly larger than -~he external 27 diameter o the conduit partS 51 and 52 and lipped packir.gs -- 1~ --1138~98 58 and 59 are disposed inside the end portions of the casing so as to ensure the tightness of the latter relatively to the pipe or conduit 51,52, Figure 3 represents one end position of the piston, in which the fluid arriving by way of the part 52 of the conduit passes through the flow ducts 61,63 and 61',63', to leave through the part 51. Quite obviously, the fluid generally fills the entire internal space of the device. As the part 60 is fast with the casing 55,56, a rotation of the latter enables the passage section for the fluid to be regulated by an angular displacement of the part 60 relatively to 52. The assembly comprising the piston and the casing is displaceable axially against the restraining force produced by thP frictlon of the packings 58 and 59 on the periphery of the condults 51,52, As a result of llpped packings being used, this restraining force increases with an increase in the fluid pressure inside the casing~
When it happens, that for example, because of a break in the conduit downstream of the device, the fluid pressure falls on this side of the device, the diffrence between the pressures being exerted on the upstream and downstream sides of the piston will exceed the threshold value which is essentially defined by the restraining force of the casing on the pipe or cond~it 51,52. The piston will then be displaced axially and, at the end of its travel, will close the opening in the packing ,4 by means of the conical 27 portion of the member 60.
- 11 ~
Once the cause for the actuation of the device has been overcome, the piston may be once again placed in its initial position, such as that shown in Figure 3, and the device reassumes its monitoring function on the pipeline or distribution system.
Figure 6 illustrates ina somewhat diagrammatic form one embodiment of the closure device, in which the piston is subjected to a magnetic restraining force which is adjustable from outside the pipe or conduit. The pipe 71 has an inlet opening 72 and an outlet opening 73 formed by a packing 74, this latter being retained by means of a closure element 75 formed with an internal connecting thread. The opposite end of the pipe 71 is closed by a member 76 having at its centre an opening for the passage ofa piston rod 80. The said opening is surrounded by a lipped packing 77 for ensuring tightness and for providing a certain retaining force which is variable with the inlet pressure of the fluid. The piston of this device is made in two parts 78 and 79, of which the latter has a conical closure part similar to the preceding examples. The two parts of the piston are mounted so that they are rotatable relatively to one another, the part 78 being guided axially by a lug 78' which engages in a longitudinal groove. In this way, only the part 79 can be displaced angularly for regula-ting the section of the fluid flow duct through the piston.
25 This adjustment is effected by means of the piston rod 80, which carries at one end an adjusting knob 81 and which, at 27 its other end, turns freely in the two parts of the piston.
. - 12 -~38Z9B
In its axial movement, the rod 80 is made fast with the pis-ton by means which are indicated diagrammatically. A pinion 82, fast with the rod 80, is clisposed inside a hollow of the member 79 and co-operates with a pinion 83 mounted on the member 78. In its turn, the pinion 83 controls an internal toothing 84 on the member 79. The assembly thus constitutes a reduction mechanism facilitating the adjustment of the section of the flow duct by means of the adjusting knob 81.
The part 78 of the piston comprises an annular ma-gnet 85 which is magnetised in the axial direction. Arranged externally of the tubular conduit 71 which, in this case, is made of a non-magnetic material, are two annular magnets 86 and 88 which are likewise magnetised axially, in the same direc-tion as the ring 85. These external annular or rlny magnets are encased in support members 87 and 89, respectively, which are displaceable axially on the conduit 71 by means of an endless screw 90 fitted in two supports 92 and 93 integral with the conduit 71. The screw 90 has a right-hand thread on a part co-operating with the support 87 and a left-hand thread on a second part co-operating with the support 89, so that a rotation of the adjusting knob 91 permits the magnets 86 and 88 to be displaced in opposite directions relatively to the conduit 71. This permits themagnetic force of attrac-tion exerted by the magnets 86 and 88 on the magnet 85 to be regulated and, consequently, the retaining force by which the piston tends to be held in its intermdiate rest position 27 against the difference in pressures being exerted on the two i~38Z98 upstream and downstream faces, respectively.
Figure 7 illustrates a modification, according to which the piston has a part 94 of magnetically permeable material co-operating with an electromagnet disposed outside the conduit 71, which here also in non-magnetic. This electro-magnet comprises an armature 95 and a coil 96 supplied by a circuit (non shown). This arrangement permits the retaining force of the piston to be regulated by an ~justment of the current passing in the coil 96 and is thus particularly well suited for a remote control of this retaining force.
Figure 8 represents another modification in a device similar to that of Figure 6, in which the similar elements have been given the same reference numerals. In the case of Figure 8, the piston 97 is also formed of two parts displa-ceable angularly relatlvely to one another and one of these parts is fast with a rod 98 passing through the wall 76 of the conduit and having an adjusting or control knob 81 its free end. The peripheral part of the piston is formed with an in-flatable packing 99 which communicates with a passage 100 passing through the piston rod 98. This passage is connected to the outside of the conduit 71 by way of a connecting member 101 to a fluid source (not shown) of adjustable pressure.
By hydraulic or pneumatic means, the adjustment of this pres-sure permits of adjusting the frictional force effective between the inflatable packing 99 and the inside wall of the conduit 71.
27 According to a modification, the passage 100 may ~i38Z98 communicate with the piston chamber through a lateral opening 102 in the rod 98, so as to cause the fluid pressure upstream of the piston to act on the packing 99 and as a result to ca~lse the retaining force to be dependent on the fluid pressure at the inlet o~ the safety device.
Figure 9 represents another constructional form of the device as regards the control section thereof. The piston, which is not shown in this Figure, is once again d.isplaceable in a cylindrical tube 103 and is fast with a control rod 108 provided with an adjusting knob 81. That part of the device which is not shown may be constructed as in the preceding Figures, the control knob 81 permitting the regulation of the section of the fluid flow duct to be supervised. The conduit 103 is extended by a tube 104 which is screwed on the end of the said conduit 103, thls latter having a closure member 105 provlded with a lipped packing 109 for ensuring the tightness of the passage of the rod 108 through the member 105. A flexible diaphragm 110 is fixed inside the tube 104 by means of a tube ; 111 held in the tube 104 by a cover 106 screwed on to the end of the tube 104. The diaphragm 110 is fixed to the rod 108 whlch extends through it, by means of a member 112 which is represented diagrammatically. A packing 107 ensures the tightness of the passage for the rod 108 through the cover 106, this latter having a fluid inlet opening 113.
A fluid inlet opening 114 may also be provided in the part of the wall 104 disposed between the diaphragm 110 and : 27 the closure plate 105 of the piston chamber. Thus, the piston ~::
~ 15 -:` ;~: ` `
~38Z98 can be controlled by the difference between the pressures obtain-ing on either side of the diaphragm 110, thereby particularly permitting the piston to be actuated in one direction or the other and/or for its restraining force to be defined. In this constructional form, the device may thus serve as a valve remotely controlled by hydraulic or pneumatic means. The fluid inlet 113 may for example be connected to a device supervising the degree of filling of a tank supplied by means of the device in Figure 9, so that the latter is actuated automatically, when a predetermined level is reached in the tank, by the pressure of the fluid admitted through the opening 113 and being exerted on the diaphragm 110, causing the displacement of the piston towards the closure or shut-off position.
The device which i8 shown in Figures 10 to 12 comprises lS a cylindrical housing 1', forming a tubular chamber. The housing 1' is formed with a lateral threaded tubular neck 2a', per-mitting it to be connected, by means of a fluid-tight union of conventional type, to an inlet pipe for fluid under pressure, and an axial threaded tubular neck 2b', permitting it to be connected to an outlet pipe for fluid under pressure. This arrangement permits the device to be incorporated into a cir-cuit or distribution system for a flow of fluid under pressure.
A piston of cylindrical section, composed of two separate parts, namely, a front part 3a' and a rear part 3b', is placed inside the housing 1'. The maximum external diameters 27 of the parts 3a' and 3b' are at least approximately equal to 1138;i~8 one another and are slightly smaller than the internal diameter of the housing 1', in order to allow the piston 3a'-3b' to slide freely, by sliding along the internal wall of the cylindrical chamber defined inside the chamber 1'. A sealing O-ring 4' encloses the part 3a' and i-t is placed in a cylindrical groove, of which the lateral sides are formed by the faces 30a' and 30b' of the parts 3a' and 3b' of the piston facing one another and perpendicular to the longitudinal a~is of the hous- -ing 1', and of which the bottom is formed by a part 20' of the peripheral face of the part 3a' of the piston, having a diame-ter smaller than the maximum external diameter of this piston part. The value of this diameter is such that, when the O-ring 4' is not subjected to any lateral force of compression by the faces 30a' and 30b', it i5 subject to a compressive force between the part 20' of the wall of the part 3a' of the piston and the inside wall of the cylindrical chamber of the housing 1', whlch is sufficient to establish a frictional force oppos-ing the displacement of the piston 3a'-3b' inside the said chamber. In the absen.ce of any compressive force on the side walls of the O-ring packing 4' by the faces 30a' and 30b', this frictional force has a minimal value corresponding to a minimum of pressure difference ~etween the downstream face and the upstream face of the piston while the apparatus is functioning~ This fr3ctional force can be regulated to higher values, as will hereinafter be described, by bringing the faces 30a' and 30b' closer to one another, so as to exert 27 a compression on the side walls of the packing 4'.
.
~138Z98 Two fluid flow orifices 5a', having the general shape of an arc of a circle are formed through the part 3a' of the piston (~igures 10 and 12) and two flow orifices 5b', having a shclpe and dimensions corresponding to the orifices Sa', are formed through the wall 3b' of the piston and are each faced opposite a corresponding orifice 5a'.
That end of the cyiindrical chamber of the housing l' which is situated alongside the outlet neck 2b' for the fluid is provided with an member 6' flared out conically towards the interior of this chamber and terminating in a cylindrical bore of the same internal diameter as that of the fluid outlet passage in the neck 2b'. The member 6' is preferably formed by a single member of a plastic material which is slightly elastically deformable.
15The ~ront end of the part 3a' of the plston forms a cone positioned on the axis of the flared part and the cylin-drical bore of the member 6', so that when the piston 3a',3b' slides in the housing l', this cone is progressively driven into this flared portion and this bore, so as to cause the progressive closure of the orifice of the fluid outlet duct, : this closing action being complete when the external wall of this cone comes to bear against the internal wall of the flar-ing in the member 6'. The member 6' is preferably made of a slightly deformable plastic material, this permitting an excellent tightness of the closure to be obtained. It is also preferable for the part 3a' of the piston, or at least 27 its conical end, to be made of a slightly deformable plastic material, for example of hard rubber, similar to or identical with the material which forms the member 6'.
It is to be noted that the conical form of the front end of the piston, as well as the partially flared form of the member 6', permit the effect known as "hammering" to be avoided at the time of closure.Thepart 3b' of this piston is provided with a cylindrical part 7' which forms the upstream face of the piston and on which is applied the force result-ing from the pressure difference between the upstream and downstream sides of the piston in the cylindrical chamber when a fluid under pressure is flowing in the circuit through the cylindrical chamber and passing through the piston 3a', 3b' by way of its flow orifices 5a' and 5b'.
A rotatable disc 8' is interposed between the part 3b' of the piston and the part 7', whlle being retained by this latter, 50 as to be ~pableofturning in the seating which is formed between the lateral rim of the part 3b' of the piston and the inside wall of the part 7' which are opposite one another (Figures 10).
The part or member 7' has extending therethrough an arcuate flow orifice 9', to which corresponds an arcuate flow orifice 10' formed through the rotatable disc 8'. As will be seen from Figure 11, it is possible by rotation of the disc 8' to bring the orifice ld' into complete or partial coincidence ~; 25 with the orifice 9' or, on the contrary, to eliminate any coincidence between these two orifices, this arrangement per-:
~ 27 mittlng the section of the fluid flow duct through the piston `:
~38Z98 to ~e regulated.
The relative displacement in rotation of the parts 3a' and 3b' of the piston is prevented by the presence of two guidiny rods 11', which are screwed into the part 3a' o~ the piston and which each slide in an orifice formed inside the part 3b', so that only a movement of relative approach of the parts 3a' and 3b', one relatively to the other, is possible axially of the piston.
A headed screw 12' extending through a bore formed axially of the part 3b' of the piston and engaging in a threaded bore 13' formed axially of the part 3a' o~ the piston permits the approach of these two piston parts to be carried out, by tightening the screw 12' and consequently tightening the joint 4' between the respective faces 30a' and 30b' of these parts 3a' and 3b' of the piston. q'he tightening and slackening off of the screw 12' are obtained by causing the sliding actuating rod 16' to turn in the appropriate direction, the said rod carrying an operating knurled wheel 18' at its end situated outside the housing 1', the end of said rod arranged inside the housing 1' carrying a hexagonal head 17' which co-operates with a hexagonal recess 14' formed in the head of the screw 12'. When the screw 12' is unscrewed, the parts 3a' and 3b' of the piston are spaced from one another ` because of the elasticity of the O-ring packin~ 4', which tends to be restored to its original form.
The central part of the disc 8' is also formed with ~ 27 a hexagonal recess 15' having the same shape and dimensions as that of the recess 14'. sy a simple axial sliding movement, the rod 16' may be positioned so as to be forced to a greater or lesser extent into the piston, either into a first posi-tion of maximum insertion, permitting the co-operation of its head 17' with the hexagonal recess 14', or into a second po-sition of minimum insertion , permitting the co-operation of the head 17' with the hexagonal recess 15'. In the first posi-tion, the rotation of the rod 16' by acting on the knurled wheel 18' permits the screw 12' to be tightened or slackened off and thus, as indicated above, for the two parts 3a' and 3b' to be brought closer together, tightening the O-ring packing 4' between their faces 30a' and 30b', so as to increase the frictional force of the piston inside the housing 1', or to relax the tightness of the packing 4' so as to reduce this frictional force. The adjustment of the resistance of the piston to displacement is thus obtained.
In the second position, the rotation of the rod 16' makes it possible for the disc 8' to be turned, this having the effect, as indicated above, of causing a variation in the sec-tion of the fluid flow duct in the piston and thus permitting the adjustment of this section.
The upstream end of the housing 1' carries a threadedpart on which is screwed a threaded closure cap 19', of which the central part has drilled therein a bore formed with a sealing joint permitting the passage of the rod 16' and ~` allowing movements for axial displacement in rotation of this rod, while maintaining the tightness of the cylindrical chamber . ~13~
formed inside the housing l'. The cap 19' is preferably made of a hard plastic material. It is clear from the foregoing description that the device operates by displacement of the piston towards the downstream end until the orifice of the fluid outlet duct is closed, when the pressure difference between the upstream and downstream sides of the piston exceeds a predetermined value corresponding to the force necessary for overcoming the frictional force of the piston inside the cylindrical chamber of the housing 1'. This pressure dif-ference is itself equal to the difference between the fluid pressure upstream of the piston and the pressure drop in that part of the circuit positioned downstream of the piston.
Under normal working conditions of the fluid distribu-tion circuit, this last pressure drop is high and it may have a value almost as large as the fluid pressure upstream of the piston. It is to be noted that the opening of the fluid flow duct through the piston is preferably regulated in such a way that the pressure drop caused by the passage of the fluid through the piston is clearly lower than the pressure drop in the part of the circuit downstream of the piston.
Thus, in the absence of any anomaly in the part of the circuit placed downstream of the device, the piston remains immobile in the cylindrical chamber and the orifice of the fluid outlet duct in normally open.
On the other hand, in the event of an abnormal decrease ; in the pressure drop in this part of the circuit downstream of 27 the device, resulting for example from the breaking of the `~
: `:
~3~
pipeline or the failure of the closure valve or cock placed at the end of this pipeline, the difference in pressures between the upstream and downstream sides of the piston becomes hlgher thant the frictional force of this latter, this immediately causing the closing of the orifice oE the fluid outlet duct of the housing 1'. In this way, any undesired flow of fluid downstream of the device is avoided. The frictional force of the piston is quite obviously regulated so as to permit the variation of the pressure drop in the part of the circuit downstream of the device, within the limits corresponding to normal operation (for example, between the position of complete closure of the terminal valve and its position ofmaximum opening) without causing the displacernent of the piston.
Other applications and formsof the present device may be easily visualised by a person skilled in the art from the 17 examples as given above.
The surface of the piston exposed to the fluid pressu-re upstream of the piston is reduced, relatively to the piston surface on the downstream side of the latter, by the section 27 of the rod 4, which represents a not inconsiderable fraction 1~38Z98 of the total section of the piston. The adjustment of the sec-tion of the duct 33,34 thus makes it possible, even without other piston-restraining means, to achieve the equilibrium of said piston for a given maximum rate of flow. If it should happen that the pressure downstream of the piston falls sudden-ly, for example, as a consequence of the pipe breaking, the piston is displaced in the direction of the flow and comes to a position closing the opening 22. The pipe is thus closed automatically in such a case and may be opened again when the permitted maximum rate of flow is re-established. The piston is then placed by means of the knob 42 in an axial position per-mitting the passage of the liquid, by the rate of flow through the flow passage of the piston being regulated again as requi-red.
A supplementary means for retalnlng the plston in its posltion of equilibrium isformed by the lipped packing 6.
As the action of this packing on the rod 4 is reinforced when the pressure of the fluid flow upstream of the piston increases, the presence of this packing not only makes possible a shift in the adjustment range of the triggering threshold of the sa-fety device, but also an avoidance of an inopportune actua-tion of the said safety device, following an increase in the pressure upstream of the piston, i.e. in the entry chamber 13.
Other piston-restraining means may be used for replacing the means mentioned above or for complementing these latter.
It is in particular possible to prov~de a second lipped packing 27 on the periphery of the piston, so as to increase the restrai-ning force ~lth a sudden increase in the entry pressure. Accor-ding to a modified embodiment, the rod 4 may be of very small section and be provided with a mechanical means, for example a spring, a magnetic means, an electromagnetic means or a S hydraulic means for obtaining a restraining force on the pis-ton, which force may either be constant or variable. More par-ticulary, adjustment means may be provided for adapting the safety device to different cases of application or different operating conditions.
Figures 3 to 5 show one constructional form of the safety device, in which the piston and the means for adjusting the section of the flow duct are coaxially arranged. This device comprises a conduit formed by two coaxial parts, 51,52 which are formed t their froe ends with means, for example a screw thread, for permitting the device to be fitted lnto a fluid distrlbution system or pipeline. On lts other end, the part 51 is terminated by tw~ slde members 51' and 51" ,which extend the wall of the condui 51 in two diametrically opposite regions and form beuween them 1wo lateral openings of the pipe or conduit of the device At their free ends, the parts 51', 51"
are of a reduced thickness, so that the external diameter which they define correspondj to that of a tubular sleeve 53~formed with two diametrically opposite notches, into which are fit-ted the ends of the parts 51',51". The external surface of the sleeve j3 and of the ends Sl',Sl" are formed with a screw thread corresponding to an lnternal screw thread of the conduit 27 part 52, th IS making p~ssible the screwing of the part ~-2 on to the end of the assembly 51,53.
The pistorl of the device according to Figure 3 to 5 is rormed by two parts 60,62 of which the first has a coni-cal portion co-operating with an annular packing 54 fitted Ln the member 51. The central portion of the member 60 has extending therethrough two openings 61,61', which represent the flow duct through the piston. As the part 62 of the piston essentially has the form of a disc in which are drilled two openings permitting the passage of the slide members 51'and 51", it has in its central portior openings 63,63' of the same shape as the openings 61,61'. The part 62, guided by the side members 51',51", may only be displaced axially, whereas the part 60, connected to ~2 by means of a screw 64, can be shifted angularly in relation to 62. Thus, as shown in Flgure 5, the openings 61,63 and 61',63' can be offset from one another in order tc define th~ section of the flow duct through the device. In order to permit this adjustment, the part 60 has two latera] arms extending through the lateral openings formed in the pipe or corduit 51 between the side members 51' and 51", the ends of these arms being fitted into a casing formed of two parts 55,56, the internal dia-meter of which corresponds to the external diameter of the part 62. The two parts 55 and 56 can be screwed into one another, an annular packing 57 en uring the tightness of the assembly at this pcsition. Each part of the casing has an axial bore of a diameter sli~3htly larger than -~he external 27 diameter o the conduit partS 51 and 52 and lipped packir.gs -- 1~ --1138~98 58 and 59 are disposed inside the end portions of the casing so as to ensure the tightness of the latter relatively to the pipe or conduit 51,52, Figure 3 represents one end position of the piston, in which the fluid arriving by way of the part 52 of the conduit passes through the flow ducts 61,63 and 61',63', to leave through the part 51. Quite obviously, the fluid generally fills the entire internal space of the device. As the part 60 is fast with the casing 55,56, a rotation of the latter enables the passage section for the fluid to be regulated by an angular displacement of the part 60 relatively to 52. The assembly comprising the piston and the casing is displaceable axially against the restraining force produced by thP frictlon of the packings 58 and 59 on the periphery of the condults 51,52, As a result of llpped packings being used, this restraining force increases with an increase in the fluid pressure inside the casing~
When it happens, that for example, because of a break in the conduit downstream of the device, the fluid pressure falls on this side of the device, the diffrence between the pressures being exerted on the upstream and downstream sides of the piston will exceed the threshold value which is essentially defined by the restraining force of the casing on the pipe or cond~it 51,52. The piston will then be displaced axially and, at the end of its travel, will close the opening in the packing ,4 by means of the conical 27 portion of the member 60.
- 11 ~
Once the cause for the actuation of the device has been overcome, the piston may be once again placed in its initial position, such as that shown in Figure 3, and the device reassumes its monitoring function on the pipeline or distribution system.
Figure 6 illustrates ina somewhat diagrammatic form one embodiment of the closure device, in which the piston is subjected to a magnetic restraining force which is adjustable from outside the pipe or conduit. The pipe 71 has an inlet opening 72 and an outlet opening 73 formed by a packing 74, this latter being retained by means of a closure element 75 formed with an internal connecting thread. The opposite end of the pipe 71 is closed by a member 76 having at its centre an opening for the passage ofa piston rod 80. The said opening is surrounded by a lipped packing 77 for ensuring tightness and for providing a certain retaining force which is variable with the inlet pressure of the fluid. The piston of this device is made in two parts 78 and 79, of which the latter has a conical closure part similar to the preceding examples. The two parts of the piston are mounted so that they are rotatable relatively to one another, the part 78 being guided axially by a lug 78' which engages in a longitudinal groove. In this way, only the part 79 can be displaced angularly for regula-ting the section of the fluid flow duct through the piston.
25 This adjustment is effected by means of the piston rod 80, which carries at one end an adjusting knob 81 and which, at 27 its other end, turns freely in the two parts of the piston.
. - 12 -~38Z9B
In its axial movement, the rod 80 is made fast with the pis-ton by means which are indicated diagrammatically. A pinion 82, fast with the rod 80, is clisposed inside a hollow of the member 79 and co-operates with a pinion 83 mounted on the member 78. In its turn, the pinion 83 controls an internal toothing 84 on the member 79. The assembly thus constitutes a reduction mechanism facilitating the adjustment of the section of the flow duct by means of the adjusting knob 81.
The part 78 of the piston comprises an annular ma-gnet 85 which is magnetised in the axial direction. Arranged externally of the tubular conduit 71 which, in this case, is made of a non-magnetic material, are two annular magnets 86 and 88 which are likewise magnetised axially, in the same direc-tion as the ring 85. These external annular or rlny magnets are encased in support members 87 and 89, respectively, which are displaceable axially on the conduit 71 by means of an endless screw 90 fitted in two supports 92 and 93 integral with the conduit 71. The screw 90 has a right-hand thread on a part co-operating with the support 87 and a left-hand thread on a second part co-operating with the support 89, so that a rotation of the adjusting knob 91 permits the magnets 86 and 88 to be displaced in opposite directions relatively to the conduit 71. This permits themagnetic force of attrac-tion exerted by the magnets 86 and 88 on the magnet 85 to be regulated and, consequently, the retaining force by which the piston tends to be held in its intermdiate rest position 27 against the difference in pressures being exerted on the two i~38Z98 upstream and downstream faces, respectively.
Figure 7 illustrates a modification, according to which the piston has a part 94 of magnetically permeable material co-operating with an electromagnet disposed outside the conduit 71, which here also in non-magnetic. This electro-magnet comprises an armature 95 and a coil 96 supplied by a circuit (non shown). This arrangement permits the retaining force of the piston to be regulated by an ~justment of the current passing in the coil 96 and is thus particularly well suited for a remote control of this retaining force.
Figure 8 represents another modification in a device similar to that of Figure 6, in which the similar elements have been given the same reference numerals. In the case of Figure 8, the piston 97 is also formed of two parts displa-ceable angularly relatlvely to one another and one of these parts is fast with a rod 98 passing through the wall 76 of the conduit and having an adjusting or control knob 81 its free end. The peripheral part of the piston is formed with an in-flatable packing 99 which communicates with a passage 100 passing through the piston rod 98. This passage is connected to the outside of the conduit 71 by way of a connecting member 101 to a fluid source (not shown) of adjustable pressure.
By hydraulic or pneumatic means, the adjustment of this pres-sure permits of adjusting the frictional force effective between the inflatable packing 99 and the inside wall of the conduit 71.
27 According to a modification, the passage 100 may ~i38Z98 communicate with the piston chamber through a lateral opening 102 in the rod 98, so as to cause the fluid pressure upstream of the piston to act on the packing 99 and as a result to ca~lse the retaining force to be dependent on the fluid pressure at the inlet o~ the safety device.
Figure 9 represents another constructional form of the device as regards the control section thereof. The piston, which is not shown in this Figure, is once again d.isplaceable in a cylindrical tube 103 and is fast with a control rod 108 provided with an adjusting knob 81. That part of the device which is not shown may be constructed as in the preceding Figures, the control knob 81 permitting the regulation of the section of the fluid flow duct to be supervised. The conduit 103 is extended by a tube 104 which is screwed on the end of the said conduit 103, thls latter having a closure member 105 provlded with a lipped packing 109 for ensuring the tightness of the passage of the rod 108 through the member 105. A flexible diaphragm 110 is fixed inside the tube 104 by means of a tube ; 111 held in the tube 104 by a cover 106 screwed on to the end of the tube 104. The diaphragm 110 is fixed to the rod 108 whlch extends through it, by means of a member 112 which is represented diagrammatically. A packing 107 ensures the tightness of the passage for the rod 108 through the cover 106, this latter having a fluid inlet opening 113.
A fluid inlet opening 114 may also be provided in the part of the wall 104 disposed between the diaphragm 110 and : 27 the closure plate 105 of the piston chamber. Thus, the piston ~::
~ 15 -:` ;~: ` `
~38Z98 can be controlled by the difference between the pressures obtain-ing on either side of the diaphragm 110, thereby particularly permitting the piston to be actuated in one direction or the other and/or for its restraining force to be defined. In this constructional form, the device may thus serve as a valve remotely controlled by hydraulic or pneumatic means. The fluid inlet 113 may for example be connected to a device supervising the degree of filling of a tank supplied by means of the device in Figure 9, so that the latter is actuated automatically, when a predetermined level is reached in the tank, by the pressure of the fluid admitted through the opening 113 and being exerted on the diaphragm 110, causing the displacement of the piston towards the closure or shut-off position.
The device which i8 shown in Figures 10 to 12 comprises lS a cylindrical housing 1', forming a tubular chamber. The housing 1' is formed with a lateral threaded tubular neck 2a', per-mitting it to be connected, by means of a fluid-tight union of conventional type, to an inlet pipe for fluid under pressure, and an axial threaded tubular neck 2b', permitting it to be connected to an outlet pipe for fluid under pressure. This arrangement permits the device to be incorporated into a cir-cuit or distribution system for a flow of fluid under pressure.
A piston of cylindrical section, composed of two separate parts, namely, a front part 3a' and a rear part 3b', is placed inside the housing 1'. The maximum external diameters 27 of the parts 3a' and 3b' are at least approximately equal to 1138;i~8 one another and are slightly smaller than the internal diameter of the housing 1', in order to allow the piston 3a'-3b' to slide freely, by sliding along the internal wall of the cylindrical chamber defined inside the chamber 1'. A sealing O-ring 4' encloses the part 3a' and i-t is placed in a cylindrical groove, of which the lateral sides are formed by the faces 30a' and 30b' of the parts 3a' and 3b' of the piston facing one another and perpendicular to the longitudinal a~is of the hous- -ing 1', and of which the bottom is formed by a part 20' of the peripheral face of the part 3a' of the piston, having a diame-ter smaller than the maximum external diameter of this piston part. The value of this diameter is such that, when the O-ring 4' is not subjected to any lateral force of compression by the faces 30a' and 30b', it i5 subject to a compressive force between the part 20' of the wall of the part 3a' of the piston and the inside wall of the cylindrical chamber of the housing 1', whlch is sufficient to establish a frictional force oppos-ing the displacement of the piston 3a'-3b' inside the said chamber. In the absen.ce of any compressive force on the side walls of the O-ring packing 4' by the faces 30a' and 30b', this frictional force has a minimal value corresponding to a minimum of pressure difference ~etween the downstream face and the upstream face of the piston while the apparatus is functioning~ This fr3ctional force can be regulated to higher values, as will hereinafter be described, by bringing the faces 30a' and 30b' closer to one another, so as to exert 27 a compression on the side walls of the packing 4'.
.
~138Z98 Two fluid flow orifices 5a', having the general shape of an arc of a circle are formed through the part 3a' of the piston (~igures 10 and 12) and two flow orifices 5b', having a shclpe and dimensions corresponding to the orifices Sa', are formed through the wall 3b' of the piston and are each faced opposite a corresponding orifice 5a'.
That end of the cyiindrical chamber of the housing l' which is situated alongside the outlet neck 2b' for the fluid is provided with an member 6' flared out conically towards the interior of this chamber and terminating in a cylindrical bore of the same internal diameter as that of the fluid outlet passage in the neck 2b'. The member 6' is preferably formed by a single member of a plastic material which is slightly elastically deformable.
15The ~ront end of the part 3a' of the plston forms a cone positioned on the axis of the flared part and the cylin-drical bore of the member 6', so that when the piston 3a',3b' slides in the housing l', this cone is progressively driven into this flared portion and this bore, so as to cause the progressive closure of the orifice of the fluid outlet duct, : this closing action being complete when the external wall of this cone comes to bear against the internal wall of the flar-ing in the member 6'. The member 6' is preferably made of a slightly deformable plastic material, this permitting an excellent tightness of the closure to be obtained. It is also preferable for the part 3a' of the piston, or at least 27 its conical end, to be made of a slightly deformable plastic material, for example of hard rubber, similar to or identical with the material which forms the member 6'.
It is to be noted that the conical form of the front end of the piston, as well as the partially flared form of the member 6', permit the effect known as "hammering" to be avoided at the time of closure.Thepart 3b' of this piston is provided with a cylindrical part 7' which forms the upstream face of the piston and on which is applied the force result-ing from the pressure difference between the upstream and downstream sides of the piston in the cylindrical chamber when a fluid under pressure is flowing in the circuit through the cylindrical chamber and passing through the piston 3a', 3b' by way of its flow orifices 5a' and 5b'.
A rotatable disc 8' is interposed between the part 3b' of the piston and the part 7', whlle being retained by this latter, 50 as to be ~pableofturning in the seating which is formed between the lateral rim of the part 3b' of the piston and the inside wall of the part 7' which are opposite one another (Figures 10).
The part or member 7' has extending therethrough an arcuate flow orifice 9', to which corresponds an arcuate flow orifice 10' formed through the rotatable disc 8'. As will be seen from Figure 11, it is possible by rotation of the disc 8' to bring the orifice ld' into complete or partial coincidence ~; 25 with the orifice 9' or, on the contrary, to eliminate any coincidence between these two orifices, this arrangement per-:
~ 27 mittlng the section of the fluid flow duct through the piston `:
~38Z98 to ~e regulated.
The relative displacement in rotation of the parts 3a' and 3b' of the piston is prevented by the presence of two guidiny rods 11', which are screwed into the part 3a' o~ the piston and which each slide in an orifice formed inside the part 3b', so that only a movement of relative approach of the parts 3a' and 3b', one relatively to the other, is possible axially of the piston.
A headed screw 12' extending through a bore formed axially of the part 3b' of the piston and engaging in a threaded bore 13' formed axially of the part 3a' o~ the piston permits the approach of these two piston parts to be carried out, by tightening the screw 12' and consequently tightening the joint 4' between the respective faces 30a' and 30b' of these parts 3a' and 3b' of the piston. q'he tightening and slackening off of the screw 12' are obtained by causing the sliding actuating rod 16' to turn in the appropriate direction, the said rod carrying an operating knurled wheel 18' at its end situated outside the housing 1', the end of said rod arranged inside the housing 1' carrying a hexagonal head 17' which co-operates with a hexagonal recess 14' formed in the head of the screw 12'. When the screw 12' is unscrewed, the parts 3a' and 3b' of the piston are spaced from one another ` because of the elasticity of the O-ring packin~ 4', which tends to be restored to its original form.
The central part of the disc 8' is also formed with ~ 27 a hexagonal recess 15' having the same shape and dimensions as that of the recess 14'. sy a simple axial sliding movement, the rod 16' may be positioned so as to be forced to a greater or lesser extent into the piston, either into a first posi-tion of maximum insertion, permitting the co-operation of its head 17' with the hexagonal recess 14', or into a second po-sition of minimum insertion , permitting the co-operation of the head 17' with the hexagonal recess 15'. In the first posi-tion, the rotation of the rod 16' by acting on the knurled wheel 18' permits the screw 12' to be tightened or slackened off and thus, as indicated above, for the two parts 3a' and 3b' to be brought closer together, tightening the O-ring packing 4' between their faces 30a' and 30b', so as to increase the frictional force of the piston inside the housing 1', or to relax the tightness of the packing 4' so as to reduce this frictional force. The adjustment of the resistance of the piston to displacement is thus obtained.
In the second position, the rotation of the rod 16' makes it possible for the disc 8' to be turned, this having the effect, as indicated above, of causing a variation in the sec-tion of the fluid flow duct in the piston and thus permitting the adjustment of this section.
The upstream end of the housing 1' carries a threadedpart on which is screwed a threaded closure cap 19', of which the central part has drilled therein a bore formed with a sealing joint permitting the passage of the rod 16' and ~` allowing movements for axial displacement in rotation of this rod, while maintaining the tightness of the cylindrical chamber . ~13~
formed inside the housing l'. The cap 19' is preferably made of a hard plastic material. It is clear from the foregoing description that the device operates by displacement of the piston towards the downstream end until the orifice of the fluid outlet duct is closed, when the pressure difference between the upstream and downstream sides of the piston exceeds a predetermined value corresponding to the force necessary for overcoming the frictional force of the piston inside the cylindrical chamber of the housing 1'. This pressure dif-ference is itself equal to the difference between the fluid pressure upstream of the piston and the pressure drop in that part of the circuit positioned downstream of the piston.
Under normal working conditions of the fluid distribu-tion circuit, this last pressure drop is high and it may have a value almost as large as the fluid pressure upstream of the piston. It is to be noted that the opening of the fluid flow duct through the piston is preferably regulated in such a way that the pressure drop caused by the passage of the fluid through the piston is clearly lower than the pressure drop in the part of the circuit downstream of the piston.
Thus, in the absence of any anomaly in the part of the circuit placed downstream of the device, the piston remains immobile in the cylindrical chamber and the orifice of the fluid outlet duct in normally open.
On the other hand, in the event of an abnormal decrease ; in the pressure drop in this part of the circuit downstream of 27 the device, resulting for example from the breaking of the `~
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pipeline or the failure of the closure valve or cock placed at the end of this pipeline, the difference in pressures between the upstream and downstream sides of the piston becomes hlgher thant the frictional force of this latter, this immediately causing the closing of the orifice oE the fluid outlet duct of the housing 1'. In this way, any undesired flow of fluid downstream of the device is avoided. The frictional force of the piston is quite obviously regulated so as to permit the variation of the pressure drop in the part of the circuit downstream of the device, within the limits corresponding to normal operation (for example, between the position of complete closure of the terminal valve and its position ofmaximum opening) without causing the displacernent of the piston.
Other applications and formsof the present device may be easily visualised by a person skilled in the art from the 17 examples as given above.
Claims (10)
1. Safety closure or shut-off device suitable for a distribution system for fluid under pressure, comprising a conduit adapted to be inserted in the said system, a piston displaceable in a piston chamber forming part of the said conduit, at least one flow passageway of adjustable section being provided through the piston, an outlet orifice of the piston chamber being arranged to be closed by the piston when the piston is in one of its end positions in the piston chamber, the difference of fluid pressure between the upstream and downstream sides of the piston tending to push the piston towards said end position, the displacement of the piston being hindered by the sliding resistance of the piston, means for adjusting the section of the flow passageway independently from the position of the piston in the conduit so as to make it possible to adjust the value of the pressure difference between the upstream and downstream sides of the piston in such a manner that, up to a given maximum flow rate, the force acting to push the piston towards the position for shutting off the conduit is less than the force needed to overcome the sliding resistance, so that the piston remains immobilized in a position allowing the fluid to pass through the conduit, whereas an increase of the said pressure difference over a threshold value causes a displacement of the piston to the position for completely shutting off the conduit.
2. Device according to Claim 1, wherein the piston com-prises two parts displaceable in relation to one another for forming a flow passageway of adjustable section.
3. Device according to Claim 2, wherein one at least of the said parts of the piston has extending therethrough an orifice forming at least a part of the flow passageway, the relative displacement of the two parts of the piston permitting the section of this orifice to be regulated.
4. Device according to Claim 3, wherein the two parts are rotatable relatively to one another.
5. Device according to Claim 1, comprising restraining means for adapting the sliding resistance of the piston or the sliding member integral therewith to pressure variations upstream of the piston.
6. Device according to Claim 5, wherein the said restrain-ing means are adjustable from outside the conduit of the device.
7. Device according to Claim 2, in which a mechanical member extends through the wall of the conduit, this member being coupled to one of the parts of the piston which are displaceable relatively to one another, for permitting the adjustment of the flow passageway section.
8. Device according to Claim 7, wherein the said mechanical member is a rotatable rod.
9. Device according to Claim 8, wherein the rod has a section corresponding to a substantial fraction of the section of the piston and passes through the wall of the conduit on the upstream side of the piston.
10. Device according to Claim 8, comprising a lipped packing placed around the rod between the latter and the wall of the conduit.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH474278A CH624193A5 (en) | 1978-05-02 | 1978-05-02 | Safety shut-off device for a pressurised fluid circuit or pipeline |
| CH4742/78 | 1978-05-02 | ||
| CH1251478A CH625862A5 (en) | 1978-12-07 | 1978-12-07 | Safety shut-off device for a pressurised circuit or pipeline |
| CH12514/78 | 1978-12-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1138298A true CA1138298A (en) | 1982-12-28 |
Family
ID=25696177
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000326681A Expired CA1138298A (en) | 1978-05-02 | 1979-04-30 | Safety closure device |
Country Status (9)
| Country | Link |
|---|---|
| CA (1) | CA1138298A (en) |
| DE (1) | DE2916532A1 (en) |
| ES (1) | ES479778A1 (en) |
| FR (1) | FR2425025A1 (en) |
| GB (1) | GB2019982B (en) |
| IT (1) | IT1118543B (en) |
| NL (1) | NL7903247A (en) |
| SE (1) | SE442050B (en) |
| SU (1) | SU980635A3 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103968124B (en) * | 2014-05-04 | 2016-06-22 | 刘平 | A kind of tap water relief valve |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1303204B (en) * | Willis Oil Tool Co | |||
| FR876840A (en) * | 1939-11-06 | 1942-11-18 | Sarl Alfred Teves | Safety device for pressurized pipelines in the event of tube rupture |
| US2635629A (en) * | 1950-02-08 | 1953-04-21 | Asaro Carmelo | Excess flow cutoff valve |
| DE1086570B (en) * | 1956-05-18 | 1960-08-04 | Franz Schwarte Fa | Device for the automatic shut-off of pressure lines, especially for the braking system of motor vehicles |
| US2921440A (en) * | 1957-10-03 | 1960-01-19 | Alex Mfg Corp | Safety devices for contained fluid pressure systems |
| US3060959A (en) * | 1960-07-07 | 1962-10-30 | Olin Mathieson | Excess flow cut-off valve |
| DE1192475B (en) * | 1961-06-15 | 1965-05-06 | Akad Wissenschaften Ddr | Stepless gear for high reductions |
| DE1174125B (en) * | 1962-11-24 | 1964-07-16 | Sebastian Schlaifer | Pipe rupture valve |
| DE1192473B (en) * | 1963-10-22 | 1965-05-06 | Sebastian Schlaifer | Pipe rupture valve |
| DE2522443A1 (en) * | 1975-05-21 | 1976-12-02 | Schell Kg Hubert | Water valve with two seats, one for high pressure - preventing exit of water in case of leaks or detachment of hose |
-
1979
- 1979-03-20 FR FR7907059A patent/FR2425025A1/en active Granted
- 1979-04-03 IT IT67691/79A patent/IT1118543B/en active
- 1979-04-20 ES ES479778A patent/ES479778A1/en not_active Expired
- 1979-04-24 DE DE19792916532 patent/DE2916532A1/en not_active Withdrawn
- 1979-04-25 NL NL7903247A patent/NL7903247A/en not_active Application Discontinuation
- 1979-04-27 GB GB7914736A patent/GB2019982B/en not_active Expired
- 1979-04-27 SE SE7903747A patent/SE442050B/en unknown
- 1979-04-28 SU SU792762949A patent/SU980635A3/en active
- 1979-04-30 CA CA000326681A patent/CA1138298A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FR2425025B1 (en) | 1983-04-08 |
| IT7967691A0 (en) | 1979-04-03 |
| FR2425025A1 (en) | 1979-11-30 |
| IT1118543B (en) | 1986-03-03 |
| SE442050B (en) | 1985-11-25 |
| SE7903747L (en) | 1979-11-03 |
| SU980635A3 (en) | 1982-12-07 |
| NL7903247A (en) | 1979-11-06 |
| GB2019982A (en) | 1979-11-07 |
| DE2916532A1 (en) | 1979-11-08 |
| ES479778A1 (en) | 1980-01-16 |
| GB2019982B (en) | 1982-08-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |