EP3411769A1

EP3411769A1 - Gas pressure reducer with adjustable seat

Info

Publication number: EP3411769A1
Application number: EP17701730.8A
Authority: EP
Inventors: Daniel Becker; Philippe SCHMITZ
Original assignee: Luxembourg Patent Co SA
Current assignee: Rotarex SA
Priority date: 2016-02-02
Filing date: 2017-01-30
Publication date: 2018-12-12
Also published as: LU92967B1; LU92967A1; WO2017134014A1

Abstract

The invention is directed to a gas pressure reducer (2) comprising a body (10) with an inlet (4) intended to be in flow communication with a high pressure gas source; an outlet (6) intended to deliver the gas at a predetermined low pressure; a passage (8) through the body (10) in flow communication with the inlet (4) and with the outlet (6). A resilient element (24) engages with a pressure reducing piston (18) with a through flow path (22) formed by a needle (20). The needle (20) cooperates with a movable seat (16). The outlet pressure acts on the piston (18) in opposite direction than the spring (24) so as to urge the path (22) against the seat (16) in order to reduce the gas flow through the path (22). Pressure setting means comprise an electric actuator (32), such as a stepper motor, which moves the seat (16) along the moving direction of the piston (18) in order to set the predetermined outlet pressure.

Description

GAS PRESSURE REDUCER WITH ADJUSTABLE SEAT Technical field

[0001] The invention is directed to a gas pressure reducer. More precisely, the invention relates to a gas pressure reducer with a movable element, e.g. of the piston or membrane type, that delimits an auxiliary chamber and regulates the position of a closure element cooperating with a seat.

Background art

[0002] Prior art patent document published US2004187929 A1 discloses an adjustable pressure regulator which controls the flow of a gas from a high pressure source to a low pressure device at a predetermined outlet pressure. The regulator includes a body, a piston assembly carried by the body. The assembly has a piston, a flow conduit formed in the piston and a biasing element operably connected to the piston. The flow conduit has a regulated pressure outlet end. The piston and flow conduit are movable longitudinally in the body. A retainer element is engageable with the body and is movable toward and away from the body and the piston. A seat is carried by the retainer element and is movable therewith. The seat is engaged by the flow conduit to isolate a flow path through the regulator and disengaged from the flow conduit to open a flow path through the flow conduit. The piston assembly biasing element biases the flow conduit away from the seat to open a flow path through the regulator. Gas pressure on the piston urges the flow conduit into contact with the seat to close the flow path through the regulator. The retainer element and seat are movable toward and away from the body to vary a distance of movement of the flow conduit toward and away from the seat to vary the predetermined outlet pressure.

[0003] Such an adjustable pressure regulator intends to improve the pressure adjustment of the regulator. However, said adjustment accuracy remains reduced. Further, the regulator is bulky.

[0004] Prior art patent document published US20040200531 A1 discloses a gas pressure reducer comprising an adjustable seat. The seat is adjustably movable in a valve chamber toward and away from the piston in a translation motion. The adjustable seat is set in position by means of an adjustment screw. This screw is externally accessible by an external tool.

[0005] Prior art patent document published DE 34 05 954A1 A1 discloses a gas pressure reducer comprising an adjustable passage. The passage is defined between a shutter linked to a sliding piston, and a radial hole drilled in a tube. This tube is pivoted by an actuator so that the radial hole is rotated along an helicoidally free edge of the shutter, thus achieving pressure reduction as the free edge is linked to the piston.

Summary of invention

Technical Problem

[0006] The invention has for technical problem to overcome at least one of the disadvantages mentioned in the prior art. More precisely, the invention has for technical problem to increase the safety of a gas pressure reducer. The invention also aims at accelerating the tuning of the predetermined outlet pressure of a known amount.

Technical solution

[0007] The invention is directed to a gas pressure reducer comprising : a body; an inlet; an outlet; a passage through the body in flow communication with the inlet and with the outlet; a seat in the passage; a closing portion cooperating with the seat for varying the cross-section of the passage and reducing the pressure; a regulating element delimiting a chamber downstream of the seat and moving the closing portion for achieving the predetermined reduced pressure at the outlet; wherein the pressure reducer further comprises: an electric actuator adapted for moving the seat along a moving direction of the closing element in order to adjust the predetermined outlet pressure.

[0008] gas pressure reducer comprising : a body; an inlet intended to be in flow communication with a high pressure gas source; an outlet intended to deliver the gas at a predetermined reduced pressure; a passage through the body in flow communication with the inlet and with the outlet; a seat; pressure setting means moving the seat; a resilient element; and a movable pressure reducing piston with a through flow path cooperating with the seat; the gas pressure regulator being configured such that the outlet pressure pushes the piston in opposite direction than the resilient element so as to close the path against the seat; wherein that the pressure setting means comprise an electric actuator which moves the movable seat along the moving direction of the piston, notably in order to set the predetermined outlet pressure .

[0009] According to a preferred embodiment, the electric actuator comprises a stepper motor.

[0010] According to a preferred embodiment, the body comprises two branches with extremities where the electric actuator is fixed.

[001 1] According to a preferred embodiment, the body comprises a cavity which is delimited by the electric actuator and which is opened outside the gas pressure reducer.

[0012] According to a preferred embodiment, the gas pressure reducer in accordance with claim 4, wherein the cavity is a through channel, said channel possibly crossing the body perpendicularly to the inlet and/or to the outlet.

[0013] According to a preferred embodiment, the body comprises a flow portion crossed by the gas, and an electric actuator fixing portion, said portions being separated from each other, preferably the body comprises a plate portion separating the flow portion from the fixing portion.

[0014] According to a preferred embodiment, the electric actuator comprises a rotating electric machine and/or a leadscrew.

[0015] According to a preferred embodiment, the electric actuator comprises a fixing element beside the body which is fixed to the seat.

[0016] According to a preferred embodiment, the gas pressure reducer comprises a flow limiter, notably arranged at the inlet or at the outlet.

[0017] According to a preferred embodiment, the passage comprises a flow restriction; preferentially between the inlet and the seat, and/or between the piston and the outlet. [0018] According to a preferred embodiment, the body comprises a flow junction between the inlet and the seat, said flow junction comprising a portion of reduced diameter forming the flow restriction.

[0019] According to a preferred embodiment, at pressure equilibrium; the piston is at the same place with respect to the body in the open state and in the closed state.

[0020] According to a preferred embodiment, the regulating element is a piston.

[0021] According to a preferred embodiment, the gas pressure reducer comprises a needle forming the closing portion; said needle comprising a path crossed by the passage, preferably the closing portion is part of the regulating element.

[0022] According to a preferred embodiment, the piston and the needle are one piece, and/or the needle comprises a tip cooperating with the seat in order to reduce the flow through its path.

[0023] According to a preferred embodiment, the seat comprises a support portion equipped with a sealing interface able to shut off, optionally partially, the path.

[0024] According to a preferred embodiment, the seat comprises a shaft joined to the electric actuator; preferably the body comprises a seal around said shaft.

[0025] According to a preferred embodiment, the body comprises at least one cylindrical guiding surface, preferably two cylindrical guiding surfaces, preferably one of the two cylindrical guiding surfaces is arranged inside the other cylindrical guiding surface.

[0026] According to a preferred embodiment, the path closes against the seat and/or opens in order to achieve a pressure reduction.

[0027] According to a preferred embodiment, the piston is arranged in the passage.

[0028] According to a preferred embodiment, the needle comprises an axial opening.

[0029] According to a preferred embodiment, the path extends over the whole height of the piston. [0030] According to a preferred embodiment, the piston comprises an outer groove, preferably with a seal sliding in a tight fashion against the body.

[0031] According to a preferred embodiment, the body comprises a seal, for instance an O-ring, tightly engaging with the needle.

[0032] According to a preferred embodiment, the inlet and the outlet are remote from the setting means, and/or the outlet is axially remote from the seat, and/or the inlet axially levels the seat.

[0033] According to a preferred embodiment, the inlet and the passage are integrally formed in the body; said body being one piece.

[0034] According to a preferred embodiment, the gas pressure reducer comprises a lid wherein the outlet is formed; and/or the body separates the lid from the electric actuator.

[0035] According to a preferred embodiment, with respect to flow direction, the lid comprises a converging nozzle, and/or the piston comprises a diverging nozzle, optionally said nozzles facing each other.

[0036] According to a preferred embodiment, the channel joins two opposite faces of the body.

[0037] According to a preferred embodiment, the piston is totally enclosed in the body.

[0038] According to a preferred embodiment, the lead angle of the leadscrew is at most 30°, or 15° or 5°.

[0039] According to a preferred embodiment, the flow junction comprises a downstream portion facing the seat; the inner diameter of the downstream portion is smaller than the inner diameter of the flow limiter; and/or the inner diameter of the flow limiter and the inner diameter of the downstream portion are smaller than the inner diameter of the inlet.

[0040] According to a preferred embodiment, the flow limiter is a calibrated orifice.

[0041] According to a preferred embodiment, the body comprises a seat chamber with a space around the seat.

[0042] According to a preferred embodiment, the piston is separate from the seat.

[0043] According to a preferred embodiment, the plate portion is a disc portion. [0044] According to a preferred embodiment, the body comprises a pressure safety line with a safety device, said line facing the seat.

[0045] According to a preferred embodiment, the gas pressure regulator comprises a cover around the shaft.

[0046] According to a preferred embodiment, the fixing element projects away from the external surface of the body.

[0047] According to a preferred embodiment, the pressure setting means move the seat with respect to the body, and/or away and toward the outlet.

[0048] According to a preferred embodiment, the resilient element biases the piston away from the seat, notably for opening the path.

[0049] The invention is also directed to a process for leakage control in a gas supply circuit including at least one valve and a gas pressure reducer with a regulating element moving a closing portion, and an adjustable outlet pressure to a predetermined value; wherein the gas pressure reducer includes a seat which is moved by an electric actuator, and which engages with the closing portion; the process comprising the steps of: (a) shutting off the at least one valve; then (b) detecting a gas leakage occurring in the circuit; (c) reducing the predetermined outlet pressure of the gas pressure reducer, preferably the gas pressure reducer is in accordance with the invention.

[0050] According to a preferred embodiment, during the step (c) reducing, the predetermined outlet pressure is reduced by moving the seat of the gas pressure reducer toward the closing portion.

[0051] According to a preferred embodiment, during the step (b) detecting, the gas leakage is measured at the inlet of the gas pressure reducer.

[0052] According to a preferred embodiment, the gas supply circuit is a gas supply circuit of vehicle wherein the valve is upstream the gas pressure reducer, the gas supply circuit further comprising a gas storage upstream the valve, and a combustion engine of the vehicle downstream the gas pressure reducer.

[0053] According to a preferred embodiment, the valve is a first valve, the circuit further comprising a second valve, the gas pressure reducer being arranged between said valves. Advantages of the invention

[0054] The invention is particularly interesting in that the tuning of the outlet pressure occurs quickly. Then in an emergency situation, the outlet pressure may be adapted correspondingly with a reduced time response. The gas pressure reducer may be integrated in a safety system with a control unit driving it automatically.

[0055] The predetermined outlet pressure may be tuned precisely. It may be controlled dynamically, and increased or reduced of a limited amount. This may occur with a controlled acceleration, since the forces acting against the seat and the response of the electric actuator are known.

[0056] The invention also affords to replace the electric actuator without gas lost since the passage remains isolated from the environment. The seat remains in the body and may be blocked in place during replacement or control. Further, the position and the state of the seat may be checked from the environment.

[0057] The seat is secured to the electric actuator. The corresponding assembly may be mounted to the body simultaneously. This solution eases the mounting step, which become safer and cost saving. Since the actuator is able to maintain the seat in place without power, energy savings are enabled. The gas pressure reducer may keep a pressure setting passively. The energising of the reducer may be reduced to the pressure setting changes.

[0058] The invention may be involved in leakage control in a gas supply circuit.

The automatic actuation of the seat

Brief description of the drawings

[0059] Figure 1 represents a gas pressure reducer in a closed state according to a first embodiment of the invention, the seat being in a low pressure position.

[0060] Figure 2 represents a gas pressure reducer in an open state according to the first embodiment of the invention, the seat being in a low pressure position. [0061] Figure 3 represents a gas pressure reducer in a closed state according to the first embodiment of the invention, the seat being in a high pressure position.

[0062] Figure 4 represents a gas pressure reducer in an open state according to the first embodiment of the invention, the seat being set in a high pressure position.

[0063] Figure 5 represents a vehicle including a gas supply circuit in accordance with the invention.

[0064] Figure 6 represents a gas pressure reducer in an open state according to a second embodiment of the invention.

[0065] Figure 7 represents a block diagram of a process for leakage control in a gas supply circuit in accordance with the invention.

Description of an embodiment

[0066] In the following description, the word "axial" refers to the moving direction of the piston. The height is considered with respect to the moving direction of the piston. Figure 1 to 4 illustrates the gas pressure reducer according to the first embodiment of the invention.

[0067] Figure 1 represents the gas pressure reducer 2 in the closed state. The seat is set for a low outlet pressure, for instance 3 bars. The inlet pressure may be at least 50 bars.

[0068] The gas pressure reducer 2 comprises an inlet 4 and an outlet 6 which are in flow communication by means of a flow passage 8. The inlet 4 is plugged to a high pressure gas source (not represented). Said source may be a tank or a network supply. The inlet pressure may be at least 100 bars, or at least 200 bars. The outlet 6 may be in communication with distributing devices or a gas circuit (not represented). The outlet pressure may be at most 10 bars, or at most 3 bars. The outlet 6 is perpendicular to the inlet 4, and then an elbow is formed in the passage 8. The gas pressure reducer 2 may be used in automotive industry. It may feed a combustion engine driving a vehicle. [0069] The gas pressure reducer 2 comprises a body 10, for instance a main body. The passage 8 may be at least partially formed in the body 10, preferably mainly formed in the body 10. Optionally, the inlet 4 is also formed in the body 10. The outlet 6 may be formed in a lower lid 12 which may delimit the passage 8. The lid 12 is secured to the body 10 and may support several ports 14.

[0070] The gas pressure reducer 2 comprises a seat 16 and regulating element 18arranged in the passage 8. The seat 16 may be placed at the intersection of two elongated recesses. Their intersection may form a cavity 19 with a space around the seat 16. Said space allows a gas flow. The regulating element 18 may be a piston 18. The seat 16 is at least partially inside the passage 8. It is movable therein.

[0071] The gas pressure reducer 2 comprises a closing portion 20 engaging with the seat 16 so as to reduce the passage 8. The adjustment of the section of the passage 8 achieves the pressure reduction. The closing portion 20 may be formed on a needle 20. The needle 20 includes a flow path 22 which is part of the passage 8. The free end of the needle 20, which is on the opposite of the regulating element's 18main portion, faces the seat 16. The latter may be applied against the tip of the needle 20 in order to close the path 22. This limits or stops the gas flow therethrough. The closing portion 20 is driven by the regulating element 18. They may be one piece. The flow path 22 may cross the piston 18.

[0072] The piston 16 is slidingly mounted in a chamber of the passage 8. It includes two opposite faces with respect to his linear sliding direction. An upper face is toward the needle 20; and the lower face, or outlet face; is toward the outlet 6. The outlet face is subjected to the outlet pressure. The outlet pressure lifts the piston 18. It pushes the piston 18 toward the seat 16. Consequently, the needle end is pressed against the seat 16. The piston 18 includes a ring seal sliding against the body 10, which may also include another seal around the needle 20. Then, a double sealing barrier is provided between the piston 18 and the body 10. The body 10 may include a tubular portion guiding the needle 20. This portion may project within the piston receiving chamber. [0073] A resilient element 24, such as a spring, opposes the effect of the outlet pressure. It biases on the upper face of the piston 18 and abuts against the body 10. The chamber where the resilient element 24 lies may be tightly separated from the passage 8. The resilient element 24 tends to take away the needle 20 from the seat 16 in order to allow the gas flow through the path 22. Then the piston 18 is able to reduce and to regulate the outlet pressure, since said pressure closes the path 22 when said pressure is above a predetermined pressure, and open the path 22 when said pressure is below the predetermined pressure. The resilient element 24 acts against the outlet pressure. This means that the more the resilient element 24 is compressed, the higher the predetermined outlet pressure becomes.

[0074] The seat 16 may comprise a shaft 26, a support 28 and a sealing interface 30 borne by the support 28. The body 10 may comprise a seal around the seat 16, for instance around the shaft 26. The sealing interface 30 may be produced of a non-metallic material. It may be manufactured of a polymer, such as polytetrafluoroethylene or any equivalent. It may seal the path 22. The seat 16, and peculiarly its support 28 faces the inlet 4. The seat 16 translationally moves with respect to the body 10. This sliding direction is parallel to the one of the piston 18. Then, the seat 16 may be moved toward or away from the piston 18. Due to the resilient element 24, the position of the seat 16 infers with the threshold pressure enabling or disabling the gas flow through the path 22. In this way, the predetermined pressure may be set.

[0075] The actuation of the seat 16 is controlled by an electric actuator 32 which forms pressure setting means. In response of a power supply, the electric actuator 32 moves the seat 16 toward or away from the piston 18. The electric actuator 32 may be a linear actuator. It may comprise a rotor coupled to a leadscrew. The latter converts a rotating movement into a linear movement. The leadscrew prevents the inlet pressure to force against the electric actuator 32, and prevent the seat 16 from moving. Since this result is achieved without energising the electric actuator 32, the energy consumption is reduced. As a consequence, the accuracy of the seat position is preserved. The electric actuator 32 may comprise a stepper motor, which improves the moving precision of the seat 16. Thus, the outlet pressure may be controlled in a more accurate way. The electric actuator 32 and the outlet pressure maintain a gap G between the piston 18 and the lid 12. The gap G may be measured between the lid 12 and the projections 33 of the piston 18. Said projections 33 extend from the outlet face of the piston 18 toward the lid 12.

[0076] The body 8 exhibits a flow portion where the gas pressure is reduced, and a fixing portion 34 receiving the electric actuator 32. Said portions are remote from each other. They may be separated by a plate portion of the body. This architecture prevents heat produced by the electric actuator 32 to be communicated to the gas. This avoids bursts in case of flammable gas. The fixing portion 34 may comprise one or two branches 36 where the electric actuator 32 is screwed. These branches 36 increase the cooling of the body 10, and preserve the gas.

[0077] The branches 36 may be parallel. They are remote from each other and delimit a cavity. The cavity may be open on the environment of the gas pressure reducer 2, and may be bordered by the electric actuator 32. The cavity may be a channel 38. Said channel 38 may be in contact of the electric actuator 32 and of a cover 40 around the shaft 26. This cover 40 may optionally embrace a fixing element 42 securing the shaft 26 of the seat 16 to the electric actuator 32. The fixing element 42 is accessible through the channel 38 which crosses the body 10 from one side to the opposite side. Hence, the servicing is eased. The position and the state of the seat 16 may be freely examined.

[0078] Optionally, the gas pressure reducer 2 may comprise a flow limiter 44. It is arranged in order to define the maximal gas flow through the gas pressure reducer, independently from the pressures. This is achieved by a regulated orifice. Vortices devices are also considered. The flow limiter may be placed at the outlet 6, or at the inlet 4. The flow limiter 44 may comprise a calibrated orifice, or a set of calibrated orifices. These calibrated orifices may be arranged on a turning disc in order to select an orifice corresponding to a desired flow. [0079] Figure 2 represents the gas pressure reducer 2 in the open position with the low outlet pressure.

[0080] The electric actuator 32 has been moved upward in order to take the seat 16 from the piston 18. The path 22 is opened. The cavity 19 is less occupied. The gap G remains constant, but a space S has appeared between the needle 20 and the sealing interface 30. The latter are remote then. The space S mainly depends on the inlet pressure and on the gas flow rate. In a pressure equilibrium state, the gap G is the same as in the closed position. A transitory phase may show variations of the gap G. The gap G mainly depends on the position of the seat 16.

[0081] Figure 3 represents the gas pressure reducer 2 in the closed position. The seat is set for a high outlet pressure, for instance 9 bars. The inlet pressure may be at least 50 bars.

[0082] The needle 20 abuts against the seat 16 so as to close the path 22. The gap G is wider than in figures 1 and 2. The resilient element 24 is more compressed than in the previous figures.

[0083] Figure 5 represents the gas pressure reducer 2 in the open position with the high outlet pressure.

[0084] The electric actuator 32 has been moved upward in order to pull away the seat 16 from the piston 18. The path 22 is opened. The gap G is the same than in figure 3. Yet, the space S similar to the configuration of figure 2.

[0085] Figure 6 represents an automotive vehicle with a gas supply circuit 46 including a gas pressure reducer 2. The engine propels the vehicle which is represented by its driving wheels 48 and by its piston engine 50. However, the gas supply circuit 46 may equip any other installation.

[0086] The vehicle includes at least one gas storage unit 52, such as a gas cylinder. In the present case three gas storage units 52 are represented, however any other number is considered. The vehicle is equipped with a gas supply circuit 46 wherein the gas pressure reducer 2 is arranged, said gas pressure reducer 2 being in accordance with those that are described in relation with figures 1 to 4.

[0087] The electronic control unit 54 (ECU) actuates the gas pressure reducer 2 in order to set the outlet pressure of the gas. Then, said gas is supplied to the injectors 56 of the engine 50 at a controlled pressure. The gas supply circuit 46 includes a valve 58 between the gas storage units 52 and the gas pressure reducer 2. The valve 58 may be a check valve. The circuit 46 may comprise further valves, for instance the injectors 56 may be considered as valves.

[0088] A pressure sensor 60 is arranged between the valve 58 and the gas pressure reducer 2 in order to measure or to estimate the pressure in the pipe joining them. Then the pressure is measured at the inlet of the gas pressure reducer 2. The pressure sensor 60 may be electrically plugged to the electronic control unit 54 in order to detect leakage. For instance, a leakage is identified when the pressure measured by the pressure sensor 60 decreases whereas the valve 58 is closed. Leakage may be measured at the valve 58, or within the gas pressure reducer 2. Leakage may also be assessed at the injectors. Additional pressure sensors may be used and connected to the electronic control unit 54 for this purpose.

[0089] Figure 6 represents the gas pressure reducer 102 according to a second embodiment of the invention. Figure 6 keeps reference signs of the previous figures for identical or similar elements, said reference signs being increase of 100 however. Specific reference signs are used for the specific elements of this embodiment. The second embodiment is similar to the first embodiment; it substantially differs in that the body comprises a flow restriction 162. The gas pressure reducer 102 may be used in the gas supply circuit of figure 5.

[0090] The electric actuator 132 has been powered in such a way that the piston 1 18 contacts the lid 1 12. The regulating element 1 18 is pushed by the seat 1 16 through the closing portion 120. This configuration corresponds to the setting of the lowest predetermined outlet pressure that the gas pressure reducer 102 may provide.

[0091] The body 1 10 comprises a flow restriction 162. This flow restriction 162 may be formed in the flow passage 108. The flow restriction 162 may be arranged between the inlet 104 and the seat 1 16. It delimits the inlet 104, and may remain away from the seat 1 16. The flow restriction 162 may be a calibrated orifice. It may form a width reduction in the flow junction 164 between the inlet and the seat.

[0092] Alternatively or complementary, the outlet 106 may comprise a flow restriction 162.

[0093] Figure 7 represents a block diagram of a process for controlling leakage occurring in a gas supply circuit, for instance the gas supply circuit represented in figure 5.

[0094] The process may include the following steps, preferentially carried out in the following order:

[0095] (a) shutting off one or several valves of the gas supply circuit;

[0096] (b) detecting a gas leakage occurring in the circuit;

[0097] (c) reducing the predetermined outlet pressure of the gas pressure reducer. The process may be iterative, and may repeat the steps (a) to (c) continuously.

[0098] During step (b) detecting, leakages may be continuously monitored. This is checked in spite of closed state of the valves in the circuit. Detection may be achieved by measuring pressure at several points of the gas supply circuit. It is also considered to use pressure sensors on injectors or in the injection line of the engine. Other sensors may be used to identify fluid losses.

[0099] At step (c) reducing, the predetermined outlet pressure of the gas is reduced by means of the gas pressure reducer. Since it is equipped with an adjustable seat, the latter is activated by the electric actuator. The seat is moved toward the piston, such as reducing the biasing effect of the resilient element. Consequently, the counter effect of the outlet pressure acting on the piston may be lower in order to seal it against the seat. Then, the gas pressure reducer may also be used to automatically control gas leakage. The gas losses of a vehicle are controlled in a convenient manner.

Claims

1. A gas pressure reducer comprising :

- a body (10; 1 10) ;

- an inlet (4; 104);

- an outlet (6; 106);

- a passage (8; 108) through the body (10; 1 10) in flow communication with the inlet (4; 104) and with the outlet (6; 106);

- a seat (16; 1 16) in the passage;

- a closing portion (20; 120) cooperating with the seat (16; 1 16) for varying the cross-section of the passage (8; 108) and reducing the pressure;

- a regulating element (18; 1 18) delimiting a chamber downstream of the seat and moving the closing portion (20; 120) for achieving the predetermined reduced pressure at the outlet;

characterized in that the pressure reducer further comprises:

- an electric actuator (32; 132) adapted for moving the seat (16; 1 16) along a moving direction of the closing element (20; 120) in order to adjust the predetermined outlet pressure.

2. The gas pressure reducer (2; 102) in accordance with claim 1 , wherein the body (10; 1 10) comprises two branches (36) with extremities where the electric actuator (32; 132) is fixed.

3. The gas pressure reducer (2; 102) in accordance with any of claims 1 to 2, wherein the body (10; 1 10) comprises a cavity which is delimited by the electric actuator (32; 132) and which is opened outside the gas pressure reducer (2; 102).

4. The gas pressure reducer (2; 102) in accordance with any of claims 1 to 3, wherein the body (10; 1 10) comprises a flow portion crossed by the gas, and an electric actuator (32; 132) fixing portion, said portions being separated from each other, preferably the body (10; 1 10) comprises a plate portion separating the flow portion from the fixing portion.

5. The gas pressure reducer (2; 102) in accordance with any of claims 1 to 4, wherein the electric actuator (32; 132) comprises a rotating electric machine and/or a leadscrew.

6. The gas pressure reducer (2; 102) in accordance with any of claims 1 to 5, wherein the electric actuator (32; 132) comprises a fixing element (42) beside the body (10; 1 10) which is fixed to the seat (16; 1 16).

7. The gas pressure reducer (2) in accordance with any of claims 1 to 6, wherein it comprises a flow limiter (44), notably arranged at the outlet (6).

8. The gas pressure reducer (2; 102) in accordance with any of claims 1 to 7, wherein the regulating element is a piston (18; 1 18).

9. The gas pressure reducer (2; 102) in accordance with any of claims 1 to 8, wherein it comprises a needle (20; 120) forming the closing portion (20; 120), said needle comprising a path (22) crossed by the passage (8; 108), preferably the closing portion (20; 120) is part of the regulating element (18; 1 18).

10. The gas pressure reducer (2; 102) in accordance with any of claims 1 to 9, wherein the seat (16; 1 16) comprises a support portion (28) equipped with a sealing interface (30) able to shut off, optionally partially, the path (22).

1 1. The gas pressure reducer (2; 102) in accordance with any of claims 1 to 10, wherein the seat (16; 1 16) comprises a shaft (26) joined to the electric actuator (32; 132); preferably the body (10; 1 10) comprises a seal around said shaft (26).

12. A process for leakage control in a gas supply circuit (46) including at least one valve (58) and a gas pressure reducer (2; 102) with a regulating element (18; 1 18) moving a closing portion (20; 120), and an adjustable outlet pressure to a predetermined value; characterized in that the gas pressure reducer (2; 102) includes a seat (16; 1 16) which is moved by an electric actuator (32; 132), and which engages with the closing portion (20; 120); the process comprising the steps of:

(a) shutting off (200) the at least one valve (58); then (b) detecting (202) a gas leakage occurring in the circuit (46);

(c) reducing (204) the predetermined outlet pressure of the gas pressure reducer (2; 102), and in that the gas pressure reducer (2; 102) is in accordance with any of claims 1 to 1 1.

13. Process in accordance with claim 12, wherein during the step (c) reducing (204), the predetermined outlet pressure is reduced by moving the seat (16; 1 16) of the gas pressure reducer (2; 102) toward the closing portion (20; 120).

14. Process in accordance with any of claims 12 to 13, wherein the gas supply circuit (46) is a gas supply circuit (46) of vehicle wherein the valve (58) is upstream the gas pressure reducer (2; 102), the gas supply circuit (46) further comprising a gas storage (52) upstream the valve (58), and a combustion engine (50) of the vehicle downstream the gas pressure reducer (2; 102).

15. Process in accordance with any of claims 12 to 14, wherein the valve is a first valve (58), the circuit further comprising a second valve (56), the gas pressure reducer (2; 102) being arranged between said valves (56; 58).