Valve for methane in automotive systems with improved sealing

A valve (1) controls flow of methane in automotive systems and includes at least one sealing group (98) having a proximal sealing ring (99a), in direct contact with the gas in rest conditions. A distal sealing ring (99b) is made of different materials. A check valve device (120) is applicable to the valve (1) and includes an entrance sealing group (130) provided with a proximal sealing ring (130a) and a distal sealing ring (130b) made of different materials.

BACKGROUND OF THE INVENTION

The object of the present invention a valve applicable to a reservoir, usually on board a vehicle, for flow controlling of methane gas in automotive systems.

As is known, such valves are provided both with the components for carrying out the usual valve functions of supply of methane to the reservoir and of delivery of the methane to the vehicle engine, and with numerous accessory devices which for example carry out safety functions.

Currently, in the field of valves for methane, the need is felt to have valves that can control very large reservoirs, such as intended for commercial vehicles, industrial vehicles and the like.

For such valves, special technical solutions are required, which for example allow a refill of the reservoir at high speed.

In particular, among the many consequences of carrying out a supply at high speed, there is the considerable lowering of the temperature of the valve, due to contact with the flow of gas being supplied. Some experimental data show, for example, that the flow of incoming gas at high speed reaches a temperature of even −50° C. or less for short time intervals.

At such temperatures, traditional seals provided in the valve show some drawbacks that impair the optimal performance thereof, with the consequent risk of a gas leaks during refueling.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a valve for methane which meets the above requirements and overcomes the drawbacks of the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the accompanying figures, reference numeral1globally denotes a valve applicable to a reservoir (not shown) for controlling the flow of methane in automotive systems. Usually, the reservoir is installed on board a vehicle and the methane therein is stored at high pressure. The valve is permanently applied to the mouth of such a reservoir, except in case of extraordinary maintenance.

Valve1comprises a valve body2, preferably made in one piece, for example of a metal material such as brass, aluminium and the like.

The valve body2comprises in particular a neck4, preferably threaded, for example externally, for screwing with the mouth of the reservoir, and a reservoir duct6made through neck4, for the transit of methane into the internal chamber of the reservoir in a filling step of the reservoir and from the reservoir in an emptying step, in case of intervention of a safety device.

Preferably, the reservoir duct6extends along a rectilinear attachment axis Z and ends in a plurality of main apertures8, for example shaped as windows that follow one another circumferentially, placed through the side wall of neck4, for the transit of the gas.

Moreover, the valve body2comprises an entrance duct10, annularly delimited by a lateral entrance wall10a, which extends along a rectilinear entrance axis X, for the entry of methane during refueling.

In particular, the entrance duct10is adapted for connection with a charging pipe, upstream of which the user can insert the filler to supply the methane.

Valve1comprises a check valve device120, applied to the entrance duct10, at least partially housed in said entrance duct10.

The check valve device120preferably comprises a tubular main body122, which extends between a front end124, external to the valve body2, and an opposite rear end126. At the front end124there is an entrance aperture128for the connection with the charging pipe.

The main body122is applied to the entrance duct10, for example by means of an outer thread125.

Axially alongside the outer thread125, on the side facing the interior of the valve body122, device120is provided with an entrance sealing group130with the lateral wall10aof the entrance duct10.

The entrance sealing group130comprises at least a pair of entrance sealing seats, and in particular a proximal sealing seat130aand a distal sealing seat130b, with reference to the rear end126of the main body122. As shown inFIG. 4andFIG. 6, the diameter varies along the tubular main body122. The tubular body122forms a central chamber connecting the obturator chamber140and the fluid entrance front end124. The central chamber has a smaller diameter than the obturator chamber140and the fluid entrance aperture128. An outer engagement portion of the main body has an outer diameter greater than an outer diameter of the threaded portion125and axially nearer the fluid entrance end124than the threaded portion125. An outer diameter of the of the valve body proximate the sealing seats130a,130bis less than an outer diameter of the threaded portion125.

Moreover, the entrance sealing group130comprises an entrance sealing ring housed in the respective entrance sealing seat; in particular, the entrance sealing group130includes a proximal sealing ring132a, arranged in the proximal sealing seat130a, and a distal sealing ring132b, arranged in the distal sealing seat130b.

The proximal sealing ring, i.e. the innermost ring in the valve body, in direct contact with the gas in rest conditions, and the distal sealing ring, i.e. the outermost ring in the valve body, are made of different materials in order to achieve the optimum seal in different or only partially overlapping temperature ranges.

In particular, the material of the distal sealing ring has at low temperatures, for example in the range of −30° C.-50° C., an elasticity greater than the material of the proximal sealing ring.

Moreover, the material of the distal sealing ring is adapted to achieve an optimum seal even at very low temperatures, such as −70° C., even if for short periods of time.

The material of the distal sealing ring also ensures a methane seal, good hardness and thus mechanical resistance to pressure at such temperatures.

For example, according to an embodiment of the invention, the proximal sealing ring132aof the entrance sealing group130is made of fluorocarbon rubber, for example an FKM fluorocarbon rubber.

On the other hand, the distal sealing ring132bof the entrance sealing group130is for example made of a fluorosilicone rubber, such as an FMQ or an FVMQ rubber, which maintains excellent sealing properties even at low temperatures.

In other words, the proximal sealing ring is made of an effective and functional material for sealing at temperatures between +200° C. and −20° C. (or with special mixtures up to −40° C.) and the distal sealing ring is made of an effective and functional material for sealing at lower temperatures, such as between +170° C. and −50° C. (and even lower, such as −70° C. for short time intervals).

According to a preferred embodiment, the entrance sealing group130includes at least one anti-extrusion ring arranged in the relative sealing seat together with the respective sealing ring, adapted to prevent the escape of the sealing ring from its seat.

For example, the entrance sealing group130includes an anti-extrusion ring134, arranged in the distal sealing seat130btogether with the relative distal sealing ring132b.

For example, the anti-extrusion ring is made of polytetrafluoroethylene (PTFE).

The valve device120includes an obturator group140, housed in the main body122, including a check obturator142adapted to translate to allow or prevent the transit of gas through the main body122.

Preferably, moreover, the valve body2comprises an auxiliary reservoir duct14intended to be connected to a further reservoir to increase the autonomy of the vehicle.

Preferably, the auxiliary reservoir duct14extends along an auxiliary attachment axis K, for example coaxial with the entrance axis X.

Moreover, the valve body2includes a delivery duct20adapted to be connected with the vehicle engine to supply it with methane.

Preferably, the delivery duct20extends along a rectilinear delivery axis Y, for example distinct from and parallel to the entrance axis X and, if provided, to the auxiliary reservoir axis K.

Valve1further comprises a feed duct30connected upstream with the internal chamber of the reservoir and downstream with the delivery duct20, fluidically separate from the reservoir duct6.

In particular, the feed duct30comprises a by-pass duct32, placed within the reservoir duct6, separate from said reservoir duct6; for example, the by-pass duct is defined by a by-pass tube34housed in the reservoir duct6.

The feed duct30further comprises, preferably, an auxiliary passage36made in the valve body2, connectable upstream with the by-pass duct32and connectable downstream with the delivery duct20.

Preferably, between the by-pass duct32of the feed duct30and the auxiliary passage36, the valve body2has a closure seat38and, a valve seat40between the auxiliary passage36and the delivery duct20.

Preferably, valve1comprises a manual tap50, applied to the valve body2, adapted to be manipulated to engage an obturator body152with the closure seat38to obstruct, in whole or in part, the transit of the methane from the by-pass duct32to the auxiliary passage36(and thus to the delivery duct20).

The manual closing operation is necessary to perform maintenance operations downstream of valve1.

In normal operation, tap50is clearly open and the transit of methane from the by-pass conduit32to the auxiliary passage36is free.

According to a preferred embodiment, tap50includes a knob154, located outside the valve body2, rotatable about a tap axis D, such as parallel or coincident with the attachment axis Z of the reservoir duct6.

Tap50also includes a shaft156, integral with the knob and engaged with obturator152to cause the lowering (and thus the closure) or lifting (and thus the opening) thereof by the closure seat38.

Preferably, tap50also includes, between shaft156and the valve body2, a fixed bush158, crossed by shaft156before engaging with obturator152.

According to an embodiment of the invention, shaft156of tap50includes a first tap sealing group160which produces a gas seal between shaft156and bush158(or, in an embodiment variation not shown, with the surrounding wall of the valve body2).

The first tap sealing group160includes a proximal seat160a, towards the inside of the valve body, and a distal seat160bas well as respective sealing rings162a,162b, housed in the respective seats and, preferably, an anti-extrusion ring166.

As shown with reference to the entrance sealing group130, also for the first tap sealing group160the proximal sealing ring, i.e. the innermost ring in the valve body, in direct contact with the gas in rest conditions, and the distal sealing ring, i.e. the outermost ring in the valve body, are made of different materials in order to obtain an optimal seal in different or only partially overlapping temperature ranges.

According to one embodiment of the invention, bush158of tap50includes a second tap sealing group170, which forms a gas seal between the valve body2and bush158.

The second tap sealing group170includes a proximal seat170a, towards the interior of the valve body, and a distal seat170b, as well as respective sealing rings172a,172b, received in the respective locations and, preferably, an anti-extrusion ring176.

As shown with reference to the entrance sealing group130, also for the second tap sealing group170the proximal sealing ring, i.e. the innermost ring in the valve body, in direct contact with the gas in rest conditions, and the distal sealing ring, i.e. the outermost ring in the valve body, are made of different materials in order to obtain an optimal seal in different or only partially overlapping temperature ranges.

Moreover, valve1includes an electrovalve60, applied to the valve body, adapted to be operated remotely, electronically, to allow or prevent the methane flow to the delivery duct20, for example depending on the on or off condition of the engine, or more generally on the controls from the vehicle electronic control unit.

To this end, an obturator body62of electrovalve60cooperates with the valve seat40to prevent the methane flow to the delivery duct20.

Preferably, electrovalve60includes an engagement body64, for example screwed to the valve body by a threading66, within which the obturator member62of said electrovalve60is supported in a translatable manner.

According to an embodiment of the invention, the engagement body64of electrovalve60comprises an electrovalve sealing group180which forms a gas seal between the engagement body64and the valve body2.

The electrovalve sealing group180comprises a proximal seat180a, towards the interior of the valve body, and a distal seat180b, as well as respective sealing rings182a,182b, housed in the respective seats and, preferably, an anti-extrusion ring186, for example arranged in the proximal seat180, in engagement with the proximal ring182a.

Preferably, thread66is placed between the proximal seat180aand the distal seat180b.

As shown with reference to the entrance sealing group130, also for the electrovalve sealing group180the proximal sealing ring, i.e. the innermost ring in the valve body, in direct contact with the gas in rest conditions, and the distal sealing ring, i.e. the outermost ring in the valve body, are made of different materials in order to obtain an optimal seal in different or only partially overlapping temperature ranges.

Valve1further includes an excess flow blocking device70operating upstream of the feed duct30, and in particular upstream of the by-pass duct32thereof, and downstream of the main aperture8of the reservoir duct6towards the internal chamber of the reservoir.

The blocking device70is adapted to choke the transit of methane to the feed duct30in the presence of a methane flow exceeding a predefined threshold value.

For example, such a blocking device70is actuated when, due to a rupture of a tube downstream of the delivery duct20, there is an increased methane flow that escapes.

Moreover, the valve body2includes a discharge duct80in communication downstream with the external environment and connectable upstream with the reservoir duct6and, in the variants provided with the auxiliary reservoir duct14, with said auxiliary reservoir duct14.

The discharge duct80extends along a rectilinear discharge axis Y.

According to the invention, valve1further comprises a temperature-sensitive thermal safety device90operating between the reservoir duct6and the discharge duct80and adapted, in a closed configuration, to prevent the transit of methane from the reservoir duct6to the discharge duct80and in an open configuration, to allow the transit of methane from the reservoir duct6to the discharge duct80.

The thermal safety device90is adapted allow the discharge of methane from the reservoir duct6to the discharge duct80(i.e. towards the external environment) when the temperature exceeds a predefined threshold value and prevent such a discharge.

According to a preferred embodiment, the valve body2includes a safety chamber92in communication on one end with the reservoir duct6(and with the auxiliary reservoir duct14, if provided), via a safety aperture92a; on the other end, the valve body includes a rear compartment93, closed by a plug94, for example threaded.

Preferably, the safety chamber92extends along a safety chamber axis A, preferably perpendicular to the attachment axis Z of the reservoir duct6.

Preferably, moreover, the safety chamber axis A is perpendicular to the discharge axis W of the discharge duct80.

The safety chamber92is connectable with the discharge duct80and also has an abutment92b, placed for example between the safety aperture92aand the discharge duct80.

The thermal safety device90comprises a main obturator96, sealingly sliding in the safety chamber92and adapted, through a radial projection96athereof, to abut with abutment92b, defining the advance end stroke.

For example, the main obturator96includes a front sealing group98, for the seal between the safety chamber92and the discharge duct80, and/or a rear sealing group102, for the seal between the rear compartment93and the discharge duct80.

Preferably, the section on which the front sealing group98operates is less than the section on which the rear sealing group102operates.

According to an embodiment of the invention, the front sealing group98includes a proximal seat98a, close to the safety chamber92, and a distal seat98b, as well as a proximal sealing ring99ahoused in the proximal sealing seat98aand a distal sealing ring99bhoused in the distal sealing seat98b, and, preferably, an anti-extrusion ring100housed in the distal seat98b.

Likewise, the rear sealing group102includes a proximal seat102a, close to the rear compartment93, and a distal seat102b, as well as a proximal sealing ring103ahoused in the proximal sealing seat102aand a distal sealing ring103bhoused in the distal sealing seat102band, preferably, an anti-extrusion ring104housed in the distal seat102b.

As shown with reference to the entrance sealing group130, also for the front sealing group98and for the rear sealing group102the proximal sealing ring, i.e. the innermost ring in the valve body, in direct contact with the gas in rest conditions, and the distal sealing ring, i.e. the outermost ring in the valve body, are made of different materials in order to obtain an optimal seal in different or only partially overlapping temperature ranges.

The main obturator96has a through duct106, which connects the area upstream of obturator96with the downstream area, i.e. with the rear compartment93.

In particular, the through duct106is in connection with the rear compartment93through an orifice108smaller than the passage section of the remaining part of the through duct106.

The safety device90further comprises an elastic safety element110, adapted to influence in closing, for example, to push in closing, the main obturator96, towards the advance stroke end abutment92b.

For example; the elastic safety element110is in compression between plug94and the main obturator96.

The thermal safety device90further comprises a temperature-sensitive driving device220adapted to influence the main obturator96to move it and put the reservoir duct6in communication with the external environment through the discharge duct80.

In particular, the driving device220is sensitive to the external temperature and adapted to generate a pressure differential between the area upstream of the main obturator96and the area downstream of the same, i.e. the rear compartment93, in order to obtain the movement of said main obturator96and put the reservoir duct6in communication with the discharge duct80.

According to a preferred embodiment, the driving device220comprises a driving obturator222, sliding in a driving seat224.

Preferably, the driving seat224extends along a driving seat axis B, for example incident, for example orthogonally, to the safety chamber axis A.

Preferably, the driving seat224has a section smaller than the section of the safety chamber92in which the main obturator96slides and that connects the reservoir duct6with the discharge duct80.

The driving obturator222comprises a driving sealing group225for the seal with the driving seat224.

According to an embodiment of the invention, the driving sealing group225includes a proximal seat225a, next to the rear compartment93, and a distal seat225b, as well as a proximal sealing ring226ahoused in the proximal sealing seat225aand a distal sealing ring226bhoused in the distal sealing seat225b and, preferably, an anti-extrusion ring227housed in the distal seat225b.

As shown with reference to the entrance sealing group130, also for the driving sealing group180the proximal sealing ring, i.e. the innermost ring in the valve body, in direct contact with the gas in rest conditions, and the distal sealing ring, i.e. the outermost ring in the valve body, are made of different materials in order to obtain an optimal seal in different or only partially overlapping temperature ranges.

The valve body2also has a driving compartment228connected upstream with the downstream area of the main obturator96or the rear compartment93and downstream with the external environment.

For example, the driving compartment228is in connection with the external environment via a driving duct229, for example made in the valve body2, which connects it with the discharge duct80.

Preferably, the driving obturator222is adapted to close the connection between the driving compartment228and the area downstream of the main obturator96or the rear compartment93, through the driving sealing group225.

Preferably, the driving device220comprises an elastic driving element232adapted to influence in opening the driving obturator222, i.e. in the direction of moving said driving obturator222to put the area downstream of the main obturator96or rear compartment in communication with the external environment, for example through the driving compartment228.

The safety device90further comprises a thermosensitive element240sensitive to temperature which, for a temperature higher than a predefined threshold becomes yielding to the mechanical actions exerted by the driving obturator222; for example, said thermosensitive element240melts or bursts or becomes so soft as not to oppose said mechanical actions.

The thermosensitive element240is arranged to oppose the opening movement of the driving obturator122; for example, the thermosensitive element240is in abutment with the driving obturator222on one end and in abutment with a fixed element242, for example a bottom of a plug244, on the other.

Preferably, the thermosensitive element240is housed in an auxiliary compartment246, delimited by said bottom242and by the driving obturator222.

Preferably, the auxiliary compartment246is in communication with the external environment through holes246a(FIGS. 1 and 2) formed through bottom242of plug244. The driving obturator222also creates a seal with the walls of said auxiliary compartment246to prevent the escape of methane through holes246aduring the activation step of the thermal safety device.

Preferably, also plug94which closes the rear compartment93comprises a plug sealing group300to provide the seal with the surrounding wall of the valve body2.

The plug sealing group300includes a proximal seat302a, close to the rear compartment93, and a distal seat302b, as well as a proximal sealing ring304ahoused in the proximal sealing seat302aand a distal sealing ring304bhoused in the distal sealing seat302b, and, preferably, an anti-extrusion ring306housed in the distal seat302b.

As shown with reference to the entrance sealing group130, also for the plug sealing group180the proximal sealing ring, i.e. the innermost ring in the valve body, in direct contact with the gas in rest conditions, and the distal sealing ring, i.e. the outermost ring in the valve body, are made of different materials in order to obtain an optimal seal in different or only partially overlapping temperature ranges.

Innovatively, the valve according to the present invention allows maintaining a high reliability of the seals while particularly low temperatures are achieved, for example during refueling.

It is clear that a man skilled in the art may make changes to the valve described above in order to meet incidental needs, all falling within the scope of protection defined in the following claims.