Patent Description:
In a fuel cell automotive system, hydrogen is stored in a high-pressure tank, typically <NUM> or <NUM> bars. For filling, a nozzle is applied to a main inlet, from which the tank is fed. A non-return valve is generally placed along the supply line between the main mouth and the tank, which valve is necessary to prevent hydrogen from escaping when the nozzle is detached.

A multi-function valve (OTV) is applied to a flange of the tank, which valve, when connected to the supply line, allows hydrogen to be fed into the tank (refilling function) and sent to user devices downstream (fueling function). The OTV valve often contains numerous functional groups, suitable for performing safety functions or improving the operation of said valve. Among these functional groups, there is also a non-return valve.

An example of an OTV valve with a non-return valve is illustrated in <CIT> in the Applicant's name. Patent documents <CIT> and <CIT> disclose known non-return valves according to the preamble of claim <NUM>.

During the filling operations, the hydrogen flow undergoes fluctuations due, for example, to the pumping means at the filling station; these fluctuations are particularly intense during the early stages of filling, when the tank is practically empty, and during the final stages, when the tank is practically full. Said fluctuations are the basis of undesirable vibratory phenomena in the valves.

The object of the present invention is to construct a non-return valve equipped with a suitable damping device to prevent or limit said vibratory phenomena.

Said object is achieved by a non-return valve according to claim <NUM>. The dependent claims describe additional advantageous embodiments of the invention.

The features and the advantages of the non-return valve according to the present invention appear more clearly from the following description, made by way of indicative and non-limiting example with reference to the figures of the accompanying drawings, in which:.

<FIG> schematically depicts a portion of a gas flow management apparatus for a fuel cell traction system. The apparatus comprises a tank <NUM> in which hydrogen is compressed at high pressure, such as <NUM> or <NUM> bars.

A multifunction valve <NUM> (OTV valve) suitable for managing the gas flow entering the tank during filling (filling step) and exiting the tank to downstream user devices during vehicle use (fueling step) is applied to the flange of the tank <NUM>.

For filling, a nozzle <NUM> from a filling station is applied to a main mouth <NUM> of the apparatus, from which a supply line <NUM> runs which is fluidically connected to an inlet mouth <NUM> of the OTV valve <NUM>.

The apparatus comprises a first non-return valve <NUM> (NRV1 valve), operating along the supply line <NUM>, upstream of the OTV valve <NUM>.

The OTV valve <NUM> comprises a valve body 2a, usually in one piece, e.g., made of aluminum, into which ducts and compartments are made that form the gas transit lines and the seat of components of the valve.

The OTV valve <NUM> has an inlet/outlet line <NUM> that extends from the inlet mouth <NUM> to a branch point <NUM>, from where an inlet line <NUM> runs which extends to the filling mouth <NUM> through which gas is delivered into the tank <NUM>.

Preferably, a first filter <NUM> is operational along the inlet/outlet line <NUM> and, preferably downstream thereof, considering the direction of the gas during filling, a first manually operable opening/closing valve <NUM> (MV valve) is also operational therealong, which valve, during normal operation of the apparatus, is open to allow the gas flow to pass through.

Preferably, moreover, the OTV valve <NUM> comprises a flow limiting valve <NUM> (FLV valve) which is open during the normal filling operations of the tank <NUM>, operating along the inlet line <NUM>, preferably downstream of the MV valve <NUM>.

From the branch point <NUM>, moreover, an outlet line <NUM> runs which terminates in an outlet mouth <NUM> through which the gas in the tank <NUM> is delivered to the user devices.

The OTV valve <NUM> comprises a magnetically operable solenoid valve <NUM> (SOV valve) which is operational along the outlet line <NUM>, closed during filling operations and open during the use of the apparatus.

Preferably, the OTV valve <NUM> comprises a second filter <NUM> which is operational along the outlet line <NUM>, preferably downstream of the SOV valve <NUM>.

The OTV valve <NUM> further comprises a second non-return valve <NUM> (NRV2 valve) which is operational along the outlet line <NUM>, downstream of the SOV valve <NUM>, and suitable for preventing the gas flow to the outlet mouth <NUM>. During filling operations, the NRV2 valve is closed; during fueling operations, the NRV2 valve is open.

Preferably, the NRV2 valve <NUM> is placed upstream of the second filter <NUM>, considering the direction of the gas flow during fueling operations.

Preferably, the OTV valve <NUM> comprises an excess flow valve <NUM> (EFV valve), operating along the outlet line <NUM>, preferably upstream of the NRV2 valve considering the direction of the gas flow during fueling operations, which excess flow valve is suitable for preventing or restricting the gas flow from the tank <NUM> when the flow exceeds a predefined threshold value.

Preferably, moreover, the OTV valve <NUM> comprises a temperature sensor <NUM> (T-sensor) which is configured to detect the temperature in the tank <NUM> and is connected to a temperature signal line <NUM> to carry the signal generated by the T-sensor <NUM> outside the OTV valve <NUM>.

Preferably, moreover, the OTV valve <NUM> provides an evacuation line <NUM>, configured to put the compartment inside the tank <NUM> in communication with the external environment, into which it flows via an evacuation mouth <NUM>. In said embodiment, the OTV valve <NUM> comprises a thermal safety device <NUM> (TPRD device), operational along the evacuation line <NUM>, which prevents the gas flow to the evacuation mouth <NUM> in the normal operation of the apparatus (closing configuration). Said TPRD device <NUM> comprises a temperature-sensitive element that ruptures when the sensed temperature exceeds a predefined threshold value; the rupture of the sensitive element causes it to move into an opening configuration, in which the TPRD device <NUM> allows gas to pass through, which is then abruptly discharged through the evacuation mouth <NUM>.

Preferably, moreover, the OTV valve <NUM> comprises a pressure sensor <NUM> configured to detect the gas pressure, for example immediately upstream of the SOV valve <NUM>, considering the direction of the gas flow during the fueling operations.

Preferably, moreover, the OTV <NUM> valve is equipped with a by-pass line <NUM> that connects the inlet/outlet line <NUM>, upstream of the MV valve <NUM>, and the evacuation line <NUM>; in said embodiment, the OTV valve <NUM> comprises a second manually operable opening/closing valve <NUM> (BV valve) which, during normal operation of the apparatus, is closed to prevent the gas flow from passing through.

The present invention refers to a non-return valve <NUM> that, according to the example shown, may be either the NRV1 valve <NUM> or the NRV2 valve <NUM> or both.

According to a first embodiment (<FIG>), a non-return valve <NUM> comprises a body <NUM>, for example being a portion of the valve body 2a of the OTV valve <NUM>, and an outlet <NUM>, for example formed through a bottom <NUM> of the body <NUM>.

The non-return valve <NUM> further comprises a compartment <NUM>, for example formed in the body <NUM>, and preferably delimited annularly by an annular body wall <NUM> and by the bottom <NUM>.

The non-return valve <NUM> further comprises an inlet <NUM>, e.g., formed through a bushing <NUM> applied to the body <NUM>.

The inlet <NUM> and the outlet <NUM> are configured to be in fluid communication via the compartment <NUM>.

The non-return valve <NUM> further comprises a seat <NUM> at the inlet <NUM>, which seat is flared toward the outlet <NUM>. Preferably, said seat <NUM> is made in the bushing <NUM>, downstream of the inlet <NUM>, considering the direction of the gas flow during filling operations.

Preferably, the seat <NUM> is delimited by a seat wall <NUM>, made of a polymeric material, to form a seal. Preferably, the entire bushing <NUM> is made of said polymeric material and forms a sealing gasket.

The non-return valve <NUM> further comprises a shutter <NUM>, preferably made in one piece, for example of aluminum or stainless steel, and suitable for closing the fluid connection between the inlet <NUM> and the outlet <NUM>. In particular, the shutter <NUM> is translatable along a shutter axis X between a closing position, in which it engages with the seat <NUM> and closes the fluid connection between the inlet <NUM> and the outlet <NUM>, and an opening position, in which it is disengaged from the seat <NUM>, so that the inlet <NUM> and the outlet <NUM> are in communication.

The shutter <NUM> comprises a head <NUM> comprising a shutter portion <NUM>, preferably of a frustoconical shape, which is suitable for abutting tightly with the seat wall <NUM> to close the non-return valve <NUM>.

The head <NUM> further comprises at least one head passage <NUM> which connects the outside of the head <NUM> with the inside; for example, a plurality of head passages <NUM> having a progression inclined with respect to the shutter axis X is provided.

Preferably, the head <NUM> further comprises a radially projecting abutment wall <NUM> as discussed below.

The shutter <NUM> further comprises a stem <NUM> that extends predominantly along the shutter axis X and has internally a stem passage <NUM>, open towards the outlet <NUM>, into which the head passages <NUM> flow.

Externally, from the inlet side <NUM> toward the outlet side <NUM>, the stem <NUM> has a stepped conformation that forms a guide section <NUM> having a guide diameter D*, a first functional section <NUM> having a first diameter D1, and a second functional section <NUM> having a second diameter D2, where D* > D1 > D2. Preferably, the first functional section <NUM> is connected to the second functional section <NUM> by a flared, for example frustoconical, intermediate section <NUM>.

The valve <NUM> further comprises an elastically deformable damper ring <NUM>, e.g., made of PTFE, resting on the bottom <NUM> of the body <NUM> and traversed at least partially by the first functional section <NUM> of the stem <NUM> of the shutter <NUM>.

Preferably, the damper ring <NUM> has a cut <NUM> that interrupts its circumferential continuity, increasing the structural elasticity of the component.

Preferably, the damper ring <NUM> has externally a stepped conformation that forms a support portion <NUM>, having a larger diameter and directly resting on the bottom <NUM> of the body <NUM>, and a secondary portion <NUM>, having a smaller diameter and projecting axially from the support portion <NUM>.

The valve <NUM> further comprises a helical spring <NUM>, preferably made of stainless steel, which is threaded on the stem <NUM> of the shutter <NUM> and is precompressed so as to permanently bias the shutter <NUM> toward the closing configuration.

In particular, the spring <NUM> abuts with the abutment wall <NUM> and is fitted without interference on the guide section <NUM> of the stem <NUM>, and abuts with the support portion <NUM> of the damper ring <NUM> and is fitted with interference on the secondary portion <NUM> thereof. This means that the spring <NUM> is configured to radially tighten the damper ring <NUM>.

In a closing configuration of the non-return valve (<FIG>), which is achieved when the gas pressure is greater at the outlet <NUM> than at the inlet <NUM>, the spring <NUM> pushes the shutter <NUM> so that the shutter portion <NUM> is tightly abutted against the seat wall <NUM>, closing the connection between the outlet <NUM> and the inlet <NUM>. At the same time, the spring <NUM> holds the damper ring <NUM> firmly in place, resting on the bottom <NUM>.

In this configuration, the shutter is in the closing position so that the stem <NUM> does not engage the damper ring <NUM>. In particular, between the damper ring <NUM>, and in particular the secondary portion <NUM>, and the first functional section <NUM> of the stem <NUM>, there is a clearance G, despite the spring radially tightening the damper ring.

In an opening configuration of the non-return valve (<FIG>), which is achieved when the gas pressure is greater at the inlet <NUM> than at the outlet <NUM>, the action of the spring <NUM> is overcome by the gas, which pushes the shutter <NUM> back so that the shutter portion <NUM> separates from the seat wall <NUM>, opening the connection between the outlet <NUM> and the inlet <NUM>. In particular, the gas flows from the inlet <NUM>, enters the head passages <NUM> and then the stem passage <NUM>, and exits from the outlet <NUM>. The damper ring <NUM> is stationary in position, resting on the bottom <NUM> and pushed by the spring <NUM>.

In said configuration, the shutter is in the opening position so that the stem <NUM> engages the damper ring <NUM> with interference. In particular, between the damper ring <NUM>, and in particular the secondary portion <NUM>, and the first functional section <NUM> of the stem <NUM>, there is an interference I.

During filling operations, as mentioned above, there are considerable fluctuations in the entering gas pressures, especially in the initial and final stages. This causes the non-return valve to switch continuously and abruptly from the closing to the opening configuration and vice versa.

Such behavior would be the source of vibratory phenomena in the valve, as occurs in solutions of the prior art, if not for the presence of the damper ring and the continuous alternation of clearance and interference between the shutter and the damper ring.

According to a known configuration, not part of the present invention (<FIG>), the body <NUM>' is an enclosure inserted into a seat provided in the valve body.

Preferably, moreover, the head passages <NUM>' extend only radially.

Preferably, moreover, the stem <NUM>' comprises a guide section <NUM>' of the shutter <NUM>, on which the spring and a functional section <NUM> with a constant diameter that extends to the end of the stem <NUM>' are fitted.

The bottom <NUM>' of the body <NUM>' has a flared support surface <NUM>', converging toward the outlet, on which the damper ring <NUM>' rests. In other words, the compartment <NUM> is at least partially delimited by the support surface <NUM>'.

Said damper ring <NUM>' has a flared bottom surface <NUM>', corresponding to the support surface <NUM>' of the body <NUM>' with which it abuts.

The spring <NUM>' operates between the abutment wall <NUM> and damper ring <NUM>', axially pushing said damper ring. Due to the flared shape of the support surface <NUM>', the damper ring <NUM>' radially tightens (i.e., contracts) on the functional section <NUM>' of the stem <NUM>.

Between the closing configuration and the opening configuration, the magnitude of the axial action with which the spring acts on the damper ring varies; in particular, the action is less intense in the closing configuration, in which the spring is less compressed, and more intense in the opening configuration, in which the spring is more compressed.

Consequently, preferably, in the closing configuration, the damper ring (which expands) engages the functional section <NUM>' with less interference, while in the opening configuration, the damper ring (which contracts) engages the functional section <NUM>' with maximum friction, performing a damping action.

Innovatively, the non-return valve according to the present invention overcomes the drawbacks mentioned above with reference to the prior art, in that it enables vibratory phenomena that are generated during the tank filling step to be avoided or limited.

Claim 1:
Non-return valve (<NUM>) for managing a high-pressure hydrogen flow in a fuel cell automotive system, comprising:
- an outlet (<NUM>), a compartment (<NUM>), and an inlet (<NUM>), wherein the inlet (<NUM>) and the outlet (<NUM>) are configured to be in fluid communication through the compartment (<NUM>);
- a shutter (<NUM>), comprising a head (<NUM>) and a stem (<NUM>), which is translatable in the compartment (<NUM>) between a closing position, in which it closes the connection between the inlet (<NUM>) and the outlet (<NUM>), and an opening position, in which it opens the connection between the inlet (<NUM>) and the outlet (<NUM>);
- a spring (<NUM>) which is inserted onto the stem (<NUM>) of the shutter (<NUM>) and which is precompressed to permanently bias the shutter (<NUM>) towards the closing position;
- an elastically deformable damper ring (<NUM>) which is arranged in the compartment (<NUM>), coaxially to the stem (<NUM> ), and which is permanently biased by the spring (<NUM>);
wherein
- in said opening position, the damper ring (<NUM> ), under the bias of said spring (<NUM> ), grips the stem (<NUM>) of the shutter (<NUM>) with an opening damping action;
- in said closing position, the damper ring (<NUM>) disengages the stem (<NUM>) with a closing damping action which is less than the opening damping action; characterized in that
- the stem (<NUM>) comprises a first functional section (<NUM>), having a first diameter (D1), and a second functional section (<NUM>), having a second diameter (D2), where D1 > D2, and in the opening position, the damper ring grips said first functional section (<NUM>).