Differential pressure opening and excess flow closing valve for gas cylinder

A valve for a fluid, comprising: a body with an inlet, an outlet and a passage fluidly interconnecting the inlet and outlet; a shut-off device housed in the body and configured for selectively opening and closing the passage, the shut-off device comprising a main seat, a main closing element forming a channel extending there through and a pilot seat, a pilot closing element housed in the main closing element, a first compression spring, and a second compression spring; an actuating device of the shut-off device. The second compression spring is operatively mounted between the main closing element and the body and the first compression spring is stronger than the second compression spring.

The present invention is the US national stage under 35 U.S.C. § 371 of International Application No. PCT/EP2020/070366 which was filed on Jul. 17, 2020, and which claims the priority of application LU 101328 filed on Jul. 26, 2019, the content of which (text, drawings and claims) are incorporated here by reference in its entirety.

FIELD

The invention is directed to the field of valves for fluid, in particular for compressed gas, more particularly for industrial compressed gas and for being mounted on gas cylinders.

BACKGROUND

Prior art patent document published U.S. Pat. No. 3,844,312 discloses a valve for a fluid, for instance for liquefied petroleum gas tanks. The valve comprises a body that houses a shut-off device comprising a main seat and a pilot seat, for achieving a slow opening and an automatic closing in case of excess flow rate. The shut-off device comprises a main seat, a main closure element with a central passage for the fluid and a pilot seat, and a pilot closing element normally resting on said pilot seat. A first compression spring is operably mounted between the main closing element and the pilot closing element, and a second compression spring, concentric inside the first one, operatively mounted between the valve body and the pilot closing element. A cam device is provided for actuating the pilot closing element by moving said element away from the pilot seat, opening the passage and building up a counter-pressure downstream of the shut-off device. Once the pressure difference (i.e. pressure upstream minus pressure downstream) become less than the force exerted by the first compression spring, the main closing element moves away from the main seat and opens in full the passage. In the event that piping downstream of the valve experiences a break, the counter-pressure will become lower such that the above pressure difference will become greater than the force of the first compression spring, so that the main closing element will contact the main seat and close the main passage. The pilot passage will also close further to the engagement of an enlarged-diameter plug portion of the stem of the pilot closing element with a corresponding orifice in the pilot closing element.

The above teaching is interesting in that it provides on one side a slow-opening of the passage and on the other side an automatic closing of said passage in case of a too high flow rate or a loss of counter pressure. The construction of the valve is however bulky, in particular radially, and therefore not quite practicable for industrial compressed gas, i.e., at about 200 bars and on gas cylinder with a neck that shows a limited diameter.

Patent documents published US 2010/0252770 A1 and US 2016/0097444 A1 disclose similar valves for fluid with a main closing element and a pilot closing element.

SUMMARY

The invention has for technical problem to overcome at least one of the drawbacks of the above cited prior art. More specifically, the invention has for technical problem to provide a valve with a controlled opening function and/or automatic closing function in case of excess flow specially adapted for industrial compressed gas, i.e., for gas cylinders.

According to a first aspect, the invention is directed to a valve for a fluid, in particular for compressed gas, comprising a body with an inlet, an outlet and a passage fluidly interconnecting the inlet and outlet; a shut-off device housed in the body and configured for selectively opening and closing the passage, the shut-off device comprising a main seat, a main closing element configured for cooperating with the main seat and forming a channel extending there through and a pilot seat, a pilot closing element housed in the main closing element and configured for cooperating with the pilot seat, a first compression spring operatively mounted between the pilot closing element and the main closing element, and a second compression spring configured for biasing the main closing element towards the main seat; an actuating device configured for moving the pilot closing element away from the pilot seat and open the passage through the channel and, once a counter-pressure has built up downstream of the main closing element, move the main closing element away from the main seat; wherein the second spring is operatively mounted between the main closing element and the body and in a shut-off state of the shut-off device, the first compression spring is stronger than the second compression spring.

When defining the compression springs as operatively mounted between two elements, it is to be understood that the compression spring acts directly on the two elements.

According to an exemplary embodiment, the second compression spring surrounds the main closing element.

According to an exemplary embodiment, the main closing element shows an outer cylindrical surface housed in a sliding fashion in at least one bore of the body, the outer cylindrical surface showing a least one longitudinal cut-out forming the passage along the main closing element.

According to an exemplary embodiment, each of the least one longitudinal cut-out forms a flattened surface.

According to an exemplary embodiment, the least one longitudinal cut-out comprises at least three cut-outs distributed around the main closing element on the outer cylindrical surface.

According to an exemplary embodiment, the outer cylindrical surface of the main closing element comprises, relative the main seat, a distal portion housed in a distal bore of the body, with a first diameter, and a proximal portion housed in a proximal bore of the body, with a second diameter greater than the first diameter.

According to an exemplary embodiment, the outer cylindrical surface of the main closing element forms a shoulder between the distal portion and the proximal portion, the second compression spring resting on the shoulder.

According to an exemplary embodiment, the main seat is formed on a cylindrical element that is housed in a cavity formed in the body, the cylindrical element comprising a through-hole forming the passage.

According to an exemplary embodiment, the cylindrical element comprises an outer thread engaged with an inner thread of the cavity, the cylindrical element comprising a front face opposed to the main seat and provided, at an outer periphery, with prongs for engaging with a tool for screwing the cylindrical element in the cavity.

According to an exemplary embodiment, the proximal bore is formed in the cylindrical element.

According to an exemplary embodiment, the main seat is a conical surface adjacent the proximal bore.

According to an exemplary embodiment, the channel in the main closing element comprises a bore distal to the main seat and a through-hole proximal to the main seat, the pilot closing element being elongate with a distal portion, a proximal portion and a collar portion between the distal and proximal portions, the collar portion being housed in a sliding fashion in the bore and the proximal portion extending through the through-hole.

According to an exemplary embodiment, the first compression spring is slid around the distal portion of the pilot closing element and rests on the collar portion.

According to an exemplary embodiment, the pilot seat is formed by a cylindrical block of non-metallic material that is inserted into the bore of the main closing element.

According to an exemplary embodiment, the first compression spring is operatively mounted on the main closing element by resting on a pin that is inserted transversally into the main closing element.

According to an exemplary embodiment, the main closing element comprises a conical front surface with a groove housing a gasket configured for cooperating with the main seat. The gasket can an elastomer vulcanized in the groove.

According to an exemplary embodiment, the main closing element comprises a rear face distal to the main seat, configured for abutting against a circular shoulder in the body when the main closing element is away from the main seat, the rear face showing at least one transversal cut-out forming the passage at the circular shoulder when the rear face abuts against the circular shoulder.

According to an exemplary embodiment, the pilot closing element freely protrudes out of the main closing element when the shut-off device in a closed state, the actuating device being configured for contacting and moving the pilot closing element without contacting the main closing element. Freely protruding out of the main closing element means that no guiding means fixed with the body is provided.

According to a second aspect, the invention is also directed to a valve for a fluid, in particular for compressed gas, comprising a body with an inlet, an outlet and a passage fluidly interconnecting the inlet and outlet; a shut-off device housed in the body and configured for selectively opening and closing the passage, the shut-off device comprising a main seat, a main closing element configured for cooperating with the main seat, forming a channel extending there through and a pilot seat, a pilot closing element housed in the main closing element and configured for cooperating with the pilot seat; an actuating device configured for moving the pilot closing element away from the pilot seat and open the passage through the channel and, once a counter-pressure has built up downstream of the main closing element move the main closing element away from the main seat; wherein the main closing element shows an outer cylindrical surface housed in a sliding fashion in at least one bore of the body, the outer cylindrical surface showing a least one longitudinal cut-out forming the passage between the inlet and the shut-off device.

The above features of the various exemplary embodiments of the first aspect are herewith also disclosed in combination with the second aspect.

More specifically, the shut-off device can comprise a single compression spring. Also the actuating device can comprise an elastic system through which the actuating force is transmitted and be configured for contacting also the main closing element for moving the element.

Alternatively, the shut-off device can comprise a first compression spring operatively mounted between the pilot closing element and the main closing element, and a second compression spring configured for biasing the main closing element towards the main seat.

The invention is particularly interesting in that it provides solutions for rendering the valve compact and suitable for gas compressed at high pressures, i.e., at least 200 bar, and for being mounted on a gas cylinder. Both the first and second aspects solve that particular problem. In the above cited prior art U.S. Pat. No. 3,844,312, the shut-off device is particularly bulky radially. Thanks to the invention, according to both first and second aspects, the shut-off device can be designed much more compact, in particular radially.

DETAILED DESCRIPTION

FIGS.1and2are sectional views of a valve according to the invention, in a closed stated.

FIG.1is a complete view of the valve.

The valve2comprises a body4with a gas inlet6, a gas outlet8and a gas passage10interconnecting the inlet with the outlet. The gas outlet8is not well visible for it extends perpendicularly to the plane of the section. The body4is advantageously made of metal like steel, stainless steel or brass. The body4shows at its lower end, at the gas inlet6, a tapering male thread designed for engaging with a female thread on a neck of gas cylinder.

The valve2comprises also a shut-off device12housed in the body4and configured for selectively opening or closing the gas passage10. The shut-off device is operated by an actuating device14. For instance, the actuating device14comprises a pivoting lever14.1with a cam, a tappet14.2moving axially along the longitudinal axis of the valve for converting with the cam the pivoting movement of the lever14.1into a translation, and a push rod14.3. For instance, the push-rod shows a lower enlarged portion that is slidably received in a longitudinal central cavity of the body4. That enlarged portion shows an opening that is crossed by a residual pressure valve16. Such a valve is optional. It can comprise a tubular portion forming a cartridge housing a piston urged by a spring and that cooperates with a seat formed for instance on the body. The opening in the enlarged portion of the push rod is designed, for instance oblong, for allowing a translation movement along the longitudinal axis without interfering with the residual pressure valve16.

FIG.2is an enlarged view of the shut-off device12of the valve inFIG.1.

The shut-off device12comprises essentially, a main closing element18cooperating with a main seat20, a pilot closing element22cooperating with a pilot seat24formed on the main closing element18, a first compression spring operatively mounted between the main closing element18and the pilot closing element22, and a second compression spring28operatively mounted between the main closing element18and the body4.

More specifically, the main closing element18forms a central channel18.1and18.2extending through the element, the pilot closing element22being configured for closing that channel under the resilient force of the first compression spring26. The channel in the main closing element18comprises a through-hole18.1that is proximal to the main seat20and a bore that is distal to the main seat20. The pilot closing element22comprises a proximal portion22.1of a reduced diameter extending through the through-hole18.1, a distal portion22.2located in the bore18.2and a collar portion22.3located between the proximal and distal portions and housed in a sliding fashion in the bore18.2. The pilot seat24is formed for instance by a conical surface in a cylindrical block30made of a material that is softer than metal, e.g. a non-metallic material. The pilot closing element22comprises a corresponding conical surface at the junction between the pin-shaped proximal portion22.1and the collar portion22.3for contacting the conical surface of the pilot seat24. As this is apparent, the bore18.2in the distal portion of the main closing element18shows a constant diameter so that the cylindrical block30forming the pilot seat24can be inserted into the bore. It can be press-fitted so that it remains in position without further measure or action.

The first compression spring26, at one end, engages around the distal portion22.2of the pilot closing element22and abuts against the collar portion22.3thereof. The other end of the first compression spring26abuts against a pin32that is inserted transversally into the main closing element18.

In the closed state as illustrated inFIG.1, the first compressing spring26urges the pilot closing element22against the pilot seat24so as to close the channel18.1and18.2formed in the main closing element18. Also the second compression spring28urges the main closing element18against the main seat20. The gas passage10is therefore closed. The inlet pressure acting on the main closing element18and on the pilot closing element22upstream of the main and pilot seats20and24, respectively, urges these elements against their seats and therefore further tends to close the passage. That pressure can be of several hundred bar.

As this is apparent inFIG.2, the pin-shaped proximal portion22.1of the pilot closing element22protrudes out of the main closing element18and is in contact or at least in vis-à-vis of the push rod14.3of the actuating device14. Upon operation of the actuating device, the push rod14.3will be moved, for instance lowered, so as to move the pilot closing element22away from the pilot seat24and open the gas passage through the channel18.1and18.2in the main closing element18. During that movement, the first compression spring26will be further compressed and transmit a force to the main closing element18tending to move it away from its seat20. The force resulting from the inlet pressure on the main closing element18, as mentioned here above, and added to the force of the second compression spring28is however greater than that resilient force. However, once gas flows through the channel18.1and18.2, a counter-pressure on the downstream side of the main closing element18will build up with downstream connected equipment. The resulting force on the main closing element18, originating from the gas pressure, will be reduced until the sum of that resulting force and the force of the second compression spring28is lower than the resilient force of the first compression spring26. From that moment, the main closing element18will move away from the main seat20and fully open the gas passage10. This will be detailed in connection withFIGS.5to8.

The above means that if the valve's outlet8is not connected to a downstream equipment, no counter pressure is built up and the main closing element18remains in contact with the main seat20until the cylinder pressure reaches a very low value, removing the risk of cylinder tipping over by a sudden and strong gas flow out of the outlet8.

FIGS.3and4are two perspective views of the main closing element18of the shut-off device12of the valve ofFIGS.1and2. As this is apparent, the main closing element18shows a generally cylindrical outer surface18.3.1and18.3.2to be received in a sliding fashion in at least one bore formed in the body. This generally cylindrical outer surface shows however cut-outs18.4.1and18.4.2that form passage for the gas between that outer surface and the at least one bore in the body. These cut-outs are for instance four flattened areas distributed around the main closing element18. More specifically, the generally cylindrical outer surface comprises, relative to the main seat, a distal portion18.3.1and a proximal portion18.3.2with a larger diameter. A shoulder is formed between these two portions, the second compression spring28resting on that shoulder.

The main closing element18comprises a front conical surface18.5with a circular groove receiving a gasket18.6that can be vulcanised in the groove. The main closing element18comprises a rear face18.7that is generally perpendicular to the longitudinal axis of the main closing element18and showing at least one transversal cut-out18.8, for instance two cut-outs. The rear face18.7is intended to abut against a shoulder formed in the body when in a fully opened position, and the cut-outs18.8form the gas passage in that position.

Back toFIG.2, the body4shows a first bore34.1and a second bore34.2with a diameter that is less the diameter of the first bore34.1. The distal portion18.3.1(not visible inFIG.2but well inFIGS.3and4) of the outer cylindrical surface of the main closing element18is slidably received in the second bore34.2. The sectional view inFIG.2shows an important radial airgap because the section is made in the cut-outs18.4.1, that airgap corresponding to the thickness of the cut-outs.

Still with reference toFIG.2, the valve comprises a cylindrical element36mounted in the cavity of the body4, for instance by screwing. That cylindrical element36forms the main seat20and forms also a bore36.1that is adjacent the main seat20. The proximal portion18.3.2(not visible inFIG.2but well inFIGS.3and4) of the outer cylindrical surface of the main closing element18is slidably received in that bore36.1. Similarly to the distal portion, the sectional view shows an important radial airgap because the section is made in the cut-outs18.4.2, that airgap corresponding to the thickness of the cut-outs.

The cylindrical element36can comprise, on a front face that is opposite to the main seat20and at an outer periphery, prongs36.2for engaging with a tool for screwing the cylindrical element in the cavity.

FIGS.5and6are sectional views of a valve according to the invention, in a partly opened state.

FIG.5is a complete view of the valve. As this is apparent, the section is still along the longitudinal axis but reversed. The lever14.1of the actuating device is lifted so that its cam presses the tappet14.2to a lower position and lowers the push rod14.3so as to move the pilot closing element off the pilot seat.

FIG.6is an enlarged view of the shut-off device12of the valve inFIG.5.

The pilot closing element22is moved down away from the pilot seat24, thereby allowing the gas to flow at a reduced rate through the channel18.2and18.1of the main closing element18. More specifically, the gas flows along the annular space between the distal portion22.2of the pilot closing element22and the bore18.2in the main closing element18, along the first compression spring26, thereafter between the collar portion22.3of the pilot closing element22and the bore18.2in the main closing element18, and then between the pin-shaped proximal portion22.1of the pilot closing element22and the through-hole in the cylinder block30forming the pilot seat24. The mechanical play between the outer surface of the collar portion22.3and the bore18.2can be dimensioned such that the resulting cross-section is less than the resulting cross-section downstream between the pin-shaped proximal portion22.1and the through-hole in the cylinder block30. In various instances, the resulting cross-section between the collar portion22.3and the bore18.2is less than 20% of the resulting cross-section between the pin-shaped proximal portion22.1and the through-hole in the cylinder block30. This allows, at the very beginning of the opening of the channel18.1and18.2, the gas flowing with high speed between the collar portion22.3and the bore18.2to expand directly downstream of the collar portion22.3before passing through the cylinder block30, thereby limiting the potential damages to the block.

InFIG.6, the main closing element18is still in contact with the main seat20because the force of the push rod14.3transmitted by the first compression spring26is less than the opposite force being the sum of the force exerted by the second compression spring28and the force resulting of the gas pressure on the main closing element18. However, the gas flowing at limited rate through the channel18.2and18.1allows a counter-pressure to build up on the downstream side of the main closing element18up to point where the sum of the force exerted by the second compression spring28and the force resulting of the gas pressure on both sides of the main closing element18becomes less than the opposite force of the first compression spring26. In that situation, the main closing element18starts moving down and opening the passage between the main closing element18and the main seat20.

FIGS.7and8are sectional views of a valve according to the invention, in a totally opened state.

FIG.7is a complete view of the valve. The actuating device14is in the same position as inFIGS.5and6.

FIG.8is an enlarged view of the shut-off device12of the valve inFIG.7.

The forces exerted on the main closing element18by the gas pressure tending to close the main closing element18are not sufficient anymore for compensating the opposite opening force exerted by the first compression spring26, better said the difference between the force exerted by the first compression spring26and the force exerted by the second compression spring28.

As this is apparent, the rear face18.7of the main closing element18abuts against a circular shoulder34.5formed in the body4between the second bore34.2and a third bore34.4of a lower diameter. With reference toFIGS.3and4and the corresponding passage of the description, the transversal cut-outs18.8in the rear face18.7form the gas passage10at the circular shoulder34.5. In that position of the main closing element18, the force resulting of the gas pressure on both sides of the main closing element18is minimum. This means that the first and second compression springs26and28are dimensioned such that, in that position of the main closing element18, the force exerted by the first compression spring26is greater than the sum of the force exerted by the second compression spring28and the force resulting of the gas pressure on both sides of the main closing element18.

Important is to observe that inFIGS.7and8the angular position of the main closing element18is different from the previous figures. The angular position of the main closing element18is such that the section plane crosses the cylindrical outer surfaces18.3.1and18.3.2(see alsoFIGS.3and4). InFIG.8we can observe that these surfaces18.3.1and18.3.2are guided by the bores34.2and36.1. Also we can observe that the pin32(see alsoFIGS.3and4) extends in the plane of the section.

The exemplary embodiments of the invention which has been described here above is one non-limiting example, among many, of working the invention.