Patent Application
20230163327
The present invention belongs to the sector of components for fuel cell vehicle systems, designed for installation on board vehicles, such as motor vehicles, commercial vehicles, vehicles for transporting goods and people. In particular, a valve for managing the flow of gas, in particular, hydrogen, between a tank and the fuel cell group, is the subject of the present invention.
As known, a fuel cell vehicle system comprises a tank for storing high-pressure hydrogen, up to 350 or 700 bars, a multi-function valve (often referred to as an OTV valve), applied to the tank, a pressure reducing valve (referred to as HPR valve), downstream of the OTV valve, further secondary valves, downstream of the HPR valve, and finally the fuel cell group for producing an electric current.
Due to the elevated pressure of storing hydrogen in the tank, the role of the HPR valve is fundamental; in fact, if the hydrogen were supplied to the fuel cell group at elevated pressures, it would risk breaking. Therefore, it is essential to also comprise safety systems to prevent the high-pressure hydrogen from reaching the fuel cell group.
To this end, known HPR valves today comprise a safety device (called a PRV valve), which, on detecting a pressure greater than a threshold value at the HPR valve outlet, allow the sudden release of hydrogen.
It is the object of the present invention to obtain a pressure reducing valve, which further increases the level of safety.
Such object is achieved by a pressure reducing valve according to claim 1. The dependent claims identify further advantageous embodiments of the invention.
The features and advantages of the pressure reducing valve according to the present invention will become apparent from the following description, given by way of a non-limiting example, according to the figures of the accompanying drawings, wherein:
With reference to the figures of the accompanying tables, an example of a fuel cell vehicle system is globally denoted with 1, comprising:
For reasons of clarity, a pressure reducing valve according to an embodiment will be described below; however, the invention is also applicable to reducing valves having a different configuration.
The HPR 6 valve comprises a valve body 20, for example, made in a single piece of a metal material, typically of aluminum, a first stage unit or high-pressure stage unit 40, arranged in the valve body 20, and a second stage unit or low-pressure stage unit 60, arranged in the valve body 20 downstream of the first stage unit 40.
The HPR 6 valve further comprises an inlet body 22, having an inlet 24, applied to the valve body 20 upstream of the first stage unit 40, and an outlet body 26, having an outlet 28, applied to the valve body 20 downstream of the second stage unit 60.
The valve body 20 has a calibrated inlet passage 30, a first stage piston chamber 32, an intermediate passage 34, a second stage piston chamber 36 and an outlet passage 38.
The first stage unit 40 comprises a first stage piston 42, elastic thrust means 44, a front gasket 46 and a rear gasket 48. The first stage piston 42, cooperating with the gaskets, 46, 48, is slidable sealingly housed in the first stage piston chamber 32.
The first stage piston 42 is configured to act as a splitter between the inlet passage 30 and the intermediate passage 34.
The second stage unit 60 comprises a second stage piston 62 , elastic thrust means 64, a front gasket 66 and a rear gasket 68. An internal passage 70 is made between the ends of the second stage piston 62. The second stage piston 62, cooperating with the gaskets, 66, 68, is slidable sealingly housed in the second stage piston chamber 36.
The second stage piston 62 is configured to act as a splitter between the intermediate passage 34 and the internal passage 70 or the outlet passage 38.
In a configuration of normal operation of the HPR valve, the opening action made on the first stage piston 42 by the pressure of the gas present in the inlet passage 30 and by the thrust means 44 is balanced by the closing action made on the first stage piston 42 by the pressure of the gas present in a bottom compartment 54; in such a configuration, the first stage piston 42 splits the passage between the inlet passage 30 and the intermediate passage 34, causing a drop in pressure.
Similarly, in such configuration, the opening action made on the second stage piston 62 by the pressure of the gas present in the intermediate passage 34 and by the thrust means 64 is balanced by the closing action made on the second stage piston 62 by the pressure of the gas present in the outlet passage 38; in such a configuration, the second stage piston 62 splits the passage between the intermediate passage 34 and the internal passage 70 or the outlet passage 38, causing a further drop in pressure.
The HPR 6 valve further comprises a primary safety device 80 adapted to make a sudden exit of the gas from the outlet passage 38 when the pressure of the gas in said outlet passage 38 exceeds a predetermined threshold value.
For example, the outlet body 26 is provided with a safety passage 82 in communication with the outlet passage 38, which is closed by a shutter 84 of the primary safety device 80. Said primary safety device 80 further comprises thrust means 86 adapted to permanently act in order to keep the shutter 84 on closing of the safety passage 82.
When the pressure of the gas in the outlet passage 38 exceeds the predetermined threshold value, the shutter 84 opens the safety passage 82 and the gas suddenly exits outside through said safety passage 82, for example, by passing inside a shutter-door 88 of the primary safety device 80, inside a spring 90 of the thrust means 86 and through a vent hole 92 made in a closing body 94 of the primary safety device 80.
From the configuration of normal operation, it is possible that, for example, due to a jamming of the first stage piston or the second stage piston, the gas pressure in the outlet passage 38 increases, until it exceeds the predetermined threshold value, causing the activation of the primary safety device 80.
Preferably, the primary safety device 80 is reversible, since when the gas pressure in the outlet passage 38 returns below the threshold value, the shutter 84 closes the safety passage 82 again, and the HPR valve 6 returns to normal operation, if the conditions are right.
Furthermore, according to the invention, there is comprised a secondary safety device 200, mechanically independent of the first stage unit 40, preferably acting upstream of the first stage unit 40, to limit the passage of gas from the inlet 24 to the inlet passage 30 when the gas flow exceeds a predetermined threshold value.
According to an embodiment, the inlet body 22 has an upstream duct 100 with a calibrated section, in communication with the inlet 24, a main compartment 102, upstream of which the upstream duct 100 opens out, and a downstream duct 104, downstream of the main compartment 102, in communication with the inlet passage 30 of the valve body 20.
The secondary safety device 200 comprises a flow shutter 202 accommodated in the main compartment 102, which is configured to be hit by the gas flow passing from the upstream duct 100 towards the downstream duct 104 and movable beneath the action of said gas flow to limit the passage of the gas from the upstream duct 100 towards the downstream duct 104.
According to a preferred embodiment, the flow shutter 202 consists of an element extending along a shutter axis X, between an upstream end 204, facing the upstream duct 100, and a downstream end 206, facing the downstream duct 104. The flow shutter 202 has an internal shutter passage 208, between the upstream end 204, where at least one inlet opening 204a opens, and the downstream end 206, where at least one outlet opening 206a opens.
For example, the inlet opening 204a is arranged on a plane orthogonal to the shutter axis X, for example, coaxial to the section of the upstream duct 100 and preferably has a greater diameter than that of the section of the upstream duct 100.
For example, furthermore, a plurality of outlet openings 206a is provided, arranged in a ring, forming radial passages between the shutter passage 208 and the downstream duct 104.
Preferably, furthermore, an auxiliary opening 206b is present at the downstream end 206, for example, coaxial to the inlet opening 204a.
The secondary safety device 200 further comprises thrust means 210, comprising, for example, a spring 212, permanently acting on the flow shutter 202 to keep the gas passing from the upstream duct 100 to the downstream duct 104.
For example, the thrust means 210 act to keep the upstream end 204 of the flow shutter 202 in abutment against the wall in which the upstream duct 100 opens.
According to a preferred embodiment, the connection between the main compartment 102 and the downstream duct 104 is made by a main aperture 214, which, in order to limit the passage of gas towards the downstream duct, 104, is closed by the downstream end 206 of the flow shutter 202.
For example, the main aperture 214 is delimited by an abutment wall 216, having a truncated-cone shaped abutment surface 218, converging towards the main aperture 214. Correspondingly, the downstream end 206 of the flow shutter 202 comprises an annular closing wall 220, having a truncated-cone shaped closing surface 222, converging in the closing direction.
According to a preferred embodiment, the secondary safety device 200 comprises a compass 224, accommodated in the main compartment 102, for example, screwed therein, comprising an annular guide wall 226, having an axial extension, and a bottom wall 228, having a radial extension, in which the main aperture 214 opens.
Preferably, the outer dimension of the flow shutter 202 is defined so that said shutter is translationally guided by the guide wall 226.
In a rest configuration of the secondary safety device, in which the gas flow from the upstream duct 100 towards the downstream duct 104 is less than a predetermined threshold value, the main aperture 214 is not obstructed and the gas passes from the upstream duct 100 towards the downstream duct 104. In such a configuration, the flow shutter 202 is in a limit opening position, which is such as to keep the main aperture 214 free; for example, in the limit opening position, the flow shutter 202 is in abutment against the wall in which the upstream duct 100 opens, and is kept in such a position by the action of the thrust means 210.
In a configuration of activation of the secondary safety device 200, in which the gas flow from the upstream duct 100 towards the downstream duct 104 is greater than a predetermined threshold value, the main aperture 214 is obstructed by the flow shutter 202 and the passage of gas from the upstream duct 100 towards the downstream duct 104 is lowered or stopped. In such a configuration, the action of the gas flow on the shutter has overcome the action of the thrust means 210 and the flow shutter 202 is in a limit closing position, which is such as to split or close the main aperture 214; for example, in the limit closing position, the flow shutter 202 is in abutment against the abutment wall 216, in which the main aperture 214 opens.
However, the secondary safety device 200 is configured to act in a mechanically independent manner of the first stage unit 40, in the sense that it is not influenced by the configuration of the latter, for example, by the position taken by the components thereof. Advantageously, this ensures the intervention of said secondary safety device 200 also when there is a jamming of the first stage unit, as well as of the second stage unit.
Overall, the HPR valve, equipped with the secondary safety device 200, comprises three operating configurations:
Innovatively, the valve according to the present invention, equipped with secondary safety device, allows an increase in the level of reliability, since it blocks the gas flow upstream of the pressure reducer, in the case where, despite the gas exiting outside due to an overpressure, the flow of gas towards the pressure reducer continues to increase.
As anticipated, the pressure reducing valve described above is one example of application of the invention.
According to a variant, the pressure reducing valve is provided with only one pressure reducing stage and the secondary safety device is arranged upstream of said single reducing stage.
According to a further variant, the pressure reducing valve is devoid of a primary safety device arranged downstream of the second reducing stage or downstream of the single reducing stage, and is provided only with the secondary safety device, arranged upstream of the first reducing stage or upstream of the single reducing stage.
According to a further variant, the secondary safety device acts downstream of the first stage unit, but upstream of the second stage unit.
According to the variants described above, the pressure reducing stages are mechanical.
According to a further variant, at least one of the reducing stages is electronic. In other words, in such an embodiment variant, the piston, which creates the restriction causing the reduction in pressure, is activated by a proportional solenoid, to which a signal is sent which is representative of the gas pressure upstream of the piston and translationally controls said piston so as to increase or reduce the restriction, thus decreasing or increasing the gas pressure downstream of the piston, respectively.
Clearly, in order to satisfy contingent needs, a person skilled in the art can make changes to the reducing valve described above, all contained in the scope of protection as defined by the following claims, as well as the aforesaid variants.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102020000005749 | Mar 2020 | IT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2021/052035 | 3/11/2021 | WO |
