Actuator valve for regulating a gas and supply system for a consumer such as a heat engine

Abstract

An actuator valve for regulating the flow of a gas comprises: - a body (12) comprising an inlet (10) and an outlet (11) for the gas and a seat (120) between the inlet (10) and the outlet (11), the seat (120) being flared; - a needle (13) of which a first end (131) comes into contact with the seat (120) in a closed position by the support of a spring (14); - an actuator (15) tending to detach the needle (13) from the seat (120) towards an open position against the spring (14). The needle (13) comprises a circular groove (130) containing a flexible seal (16, 16', 16'') bearing against the seat (120) in the closed position. Gas supply system comprising such a valve. Figure for the abstract: Fig. 2

Description

Title of the invention: Actuator valve for regulating a gas and system for supplying a consumer such as a heat engine Technical field

[0001] The present invention generally relates to an actuator valve for regulating the pressure of a gas for a consumer, in particular for a fuel supply system of a consumer such as a combustion engine or a fuel cell. Prior art

[0002] Many stationary and mobile internal combustion engines use a compressed gas as gaseous fuel which, when mixed with air, provides the energy necessary to operate the engine. The gaseous fuel, for example compressed or liquefied natural gas (CNG) or hydrogen, is generally stored in a tank under high pressure, which may be, for example, of the order of about 700 bar. Such a pressure is generally not compatible with the operation of an internal combustion engine. Therefore, the pressure of the gas must be reduced to an acceptable level to be introduced into the internal combustion engine. The pressure level of the natural gas to be introduced into the internal combustion engine may be of the order of 2 to 10 bar and up to 40 bar for an internal combustion engine running on hydrogen.A pressure regulator is therefore installed between the fuel tank and the fuel rail / injectors to ensure the desired reduction in gaseous fuel pressure.

[0003] Many pressure regulator applications have so far used a mechanical pressure regulator to provide gas pressure reduction using a combination of valves, diaphragms and / or pistons, springs and other mechanical devices to provide gas pressure reduction. These regulators are not sufficient in the case where the requirement is a pressure level that must be matched, for example between idle operation and nominal speed.

[0004] Electronically controlled gas pressure regulators are also known. However, most known electronic gas pressure regulators for CNG applications can only operate at a pressure of up to 16 bar, making them unsuitable for hydrogen engines that operate at higher pressures, typically between 20 and 40 bar.

[0005] Another disadvantage of conventional pressure regulators for gaseous fuels is related to the interface design. The valve element usually has a conical shape that cooperates with a conical valve seat, and pressure regulation is achieved by controlling the axial position of the valve element relative to the valve seat. Depending on the configuration, it may be difficult to maintain a reduced flow area.

[0006] Finally, it is desirable to be able to use an actuator requiring little power and taking up little space. Statement of the invention

[0007] The invention aims to provide an actuator valve for regulating a gas flow by controlling the actuator, allowing fine adjustment of the flow rate while limiting the size and power of the actuator.

[0008] With these objectives in view, the invention relates to an actuator valve for regulating the flow rate of a gas, the valve comprising - a body comprising an inlet and an outlet for the gas and a seat between the inlet and the outlet, the seat being flared; - a needle, a first end of which comes into contact with the seat in a closed position by the support of a spring; - an actuator tending to detach the needle from the seat towards an open position against the spring; characterized in that the needle has a circular groove containing a flexible seal bearing against the seat in the closed position.

[0009] The movement of the needle until the seal rests against the flared seat makes it possible to modulate the gas flow from the inlet to the outlet and to stop it completely. The use of a flexible seal makes it possible to obtain the closure of the gas flow with the minimum pressure of the needle in the direction of the seat. Without intervention of the actuator, the spring keeps the needle in support and obtains the closure of the valve. The spring is calibrated according to the maximum pressure of the gas on the upstream side, that is to say on the inlet side. The flared shape of the seat allows the increase in the passage section for the gas according to the retraction of the needle by the actuator to be progressive.

[0010] According to a constructive arrangement, the circular groove comprises a bottom face of cylindrical shape with the same axis as the axis of the needle, and two flanks extending radially from the bottom face, a first flank of which is on the side of a tip of the needle and a second flank is opposite the first flank. The seal comes to bear on the bottom face, and when the needle is bearing on the seat, on the second flank. The seal is thus established on the one hand in the contact on the seat, and on the other hand in the contact against the second flank.

[0011] According to a first embodiment, the seal has a substantially polygonal section. with a base face opposite the bottom face, a first flank face opposite the first flank, a second flank face opposite the second flank and a seat face opposite the seat. The straight parts of the section can thus come to bear on the bottom of the groove, the second flank and the seat, which provides it with rigid support and limits the pressure travel of the seal against the seat.

[0012] According to an improvement, the base face of the seal is inclined relative to the longitudinal axis in the sense that the direction of the base face is concurrent with the axis of the needle opposite the first end. Thus, when the valve is closed, the retained gas can be inserted between the groove and the base face so as to tend to expand the diameter of the seal. Conversely, the seal is put in compression against the seat, which contributes to obtaining an excellent seal without having to apply the needle strongly against the seat.

[0013] According to a second embodiment, the seal is toric with a circular section. When the seal is in contact with the seat, it is retained in the circular groove and the contact zones are circular. A good capacity to provide the required seal on closing is observed, with a support provided by the spring of a moderate value. Such a seal is very standard.

[0014] According to a third embodiment, the seal is an O-ring with a D-shaped section, the straight part of the section being oriented along the axis of the torus and on the inside of the torus. The straight part of the section can thus come to bear on the bottom of the groove, which provides it with rigid support and limits the pressure travel of the seal against the seat, in comparison with the O-ring of circular section.

[0015] According to one arrangement, the seal is made of a material comprising a component from the group comprising polytetrafluoroethylene (PTFE) and ethylene-propylene-diene monomer (EPDM). The PTFE makes it possible to maintain operation with large thermal amplitudes and with very little wear. The EPDM elastomer offers greater elasticity, which makes it easier to position in the groove and makes it possible to optimize the support force by the spring.

[0016] According to an improvement, the needle has at its first end a stud which is inserted in a fitted manner into the inlet in the closed position, the stud being disengaged from the inlet in the open position. When the needle is lifted from the seat, the gas is able to flow into the clearance remaining between the inlet and the stud. This produces a low gas flow rate without the need to precisely adjust the position of the needle. This flow rate may correspond, for example, to the idle speed for a heat engine.

[0017] In particular, the radial clearance between the nipple and the inlet is between 1 pm and 10 pm.

[0018] According to a constructive arrangement, the needle comprises a stop face to limit the needle travels in the closed position while in contact with the seat. This limits the compression of the seal, which preserves its lifespan.

[0019] According to a constructive arrangement, the spring is dimensioned to provide a pressing force of the needle against the seat of between 40 and 50 N. Such a force is sufficient to maintain the needle in the closed position when the gas is supplied at a pressure of up to 50 bars.

[0020] The invention also relates to a gas supply system for a consumer, such as a heat engine or a fuel cell, the system comprising a gas tank connected to a regulating device comprising a valve as described above, the inlet of the valve being connected to the tank side, the outlet being connected to the consumer side. Brief description of the figures

[0021] The invention will be better understood and other features and advantages will appear on reading the description which follows, the description making reference to the appended drawings among which: • [Fig.l] is a schematic view of a gas supply system; • [Fig.2] is a sectional view of a valve conforming to a first mode of realization of the invention; • [Fig.3] is a detail view similar to [Fig.2] for a second embodiment, in a half-open position; • [Fig.4] is a view similar to [Fig.3] in an open position; • [Fig.5] is a view similar to [Fig.3] in a closed position; • [Fig.6] is a perspective view of the joint of the second mode of rea lization; • [Fig.7] is a sectional view of the joint of the first embodiment; • [Fig.8] is a sectional view of a joint according to a third method of rea lization of the invention. Detailed description

[0022] An actuator valve 1 is provided for a gas supply system for a consumer 2 such as a heat engine or a fuel cell, shown schematically in [Fig.l]. The system comprises a pressurized gas tank 3 connected to the consumer 2 by a pipe, in which pipe are inserted a pressure reducer 30 and a regulating device 4 integrating said valve 1 and making it possible to deliver on command the quantity of gas useful to the consumer 2. The regulating device can integrate functions of a relief valve, not shown, to limit the pressure in the network, a closing valve, not shown, and / or a controllable purge to put the installation at rest, not shown. The pressure reducer 30 reduces the gas pressure to a substantially constant level and, in the case of a liquefied gas, allows it to be gasified. In the case of hydrogen supplying an internal combustion engine, this pressure level is, for example, 25 to 50 bars. Valve 1 is, for example, configured to deliver the gas to the outlet at a regulated pressure of between 5 and 40 bars. In direct injection applications, the supply pressure may be around 50 bars and the regulation is between 20 and 40 bars, depending on the engine load. In indirect injection applications, the supply pressure is lower, around 25 bars and above, and the regulation is made from 5 bars.

[0023] The valve according to a first embodiment of the invention is shown in [Fig.2],

[0024] The valve comprises an inlet 10 connected to the side of the tank 3 and an outlet 11 connected to the side of the consumer 2. The valve comprises a body 12 comprising the inlet 10 and the outlet 11 for the gas and a seat 120 between the inlet 10 and the outlet 11, the seat 120 being flared. The valve further comprises a needle 13, a first end 131 of which comes into contact with the seat 120 in a closed position by the support of a spring 14 and an actuator 15 tending to detach the needle 13 from the seat 120 towards an open position against the spring 14. The body 12 has a generally cylindrical shape extending in a main direction. The inlet 10 has the shape of a cylindrical bore at one end of the body 12 and having an axis parallel to the main direction. The outlet 11 is formed by a plurality of radial holes 110 in the body 12, with an axis perpendicular to the main direction, and opening downstream of the seat 120.

[0025] Opposite the seat 120, the needle 13 is force-fitted onto a hollow weight called the armature 150. The armature 150 is part of the actuator 15 and is designed to be actuated by a coil (solenoid), not shown. When the coil is powered, it creates a magnetic field which acts on the armature 150 to move it to the left and lift it from the seat 120. The spring 14 is housed in the hollow of the armature 150 and acts on the latter, and therefore on the needle 13, to bring the needle 13 into contact with the seat 120.

[0026] The flared shape of the seat 120 is produced by two successive cone portions 1201, 1202. The angle between the generator of the cone of the first portion 1201 and the main direction is of the order of 40°, while that of the second portion 1202 is approximately 60°. Other shapes are possible, such as a shape with more conical portions, or in continuous variation such as a pavilion.

[0027] The needle 13 further comprises a circular groove 130 containing a flexible seal 16 bearing against the seat 120 in the closed position, as shown in [Fig. 5]. The circular groove 130 comprises a bottom face 1300 of cylindrical shape of the same axis as the axis of the needle 13, and two flanks extending radially from the bottom face 1300, of which a first flank 1301 is on the side of a tip of the needle 13 and a second flank 1302 is opposite the first flank 1301. Thus, the second flank 1302 has a larger diameter than the first flank 1301. The needle 13 further comprises a stop face 132 beyond the second flank 1302 to limit the travel of the needle 13 in the closed position while being in contact with the seat 120.

[0028] The needle 13 has at its first end 131 a stud 133 which is inserted in a fitted manner into the inlet 10 in the closed position. The radial clearance between the stud 133 and the inlet 10 is between 1 μm and 10 μm.

[0029] In this first embodiment, as shown in [Fig. 6], the seal 16 has a substantially polygonal section with a base face 160 facing the bottom face 1300, a first flank face 161 facing the first flank 1301, a second flank face 162 facing the second flank 1302 and a seat face 163 facing the seat 120. The seal 16 is made with a polytetrafluoroethylene (PTFE) based component. The junctions between the faces 160, 161, 163, 162 are chamfered. The base face 160 of the seal 16 is inclined relative to the longitudinal axis in the sense that the direction of the base face 160 is concurrent with the axis of the needle 13 opposite the first end 131. The seal 16 has for example a Shore D hardness of between 60 and 90, in particular 70 and 90.

[0030] Thus, when the valve is closed, the retained gas can be inserted between the groove 130 and the base face 160 so as to tend to expand the diameter of the seal 16. Conversely, the seal 16 is put in compression against the seat 120, which contributes to obtaining an excellent seal without having to apply the needle strongly against the seat.

[0031] The seal is placed in the groove by elastic deformation. In the case of a seal exhibiting plastic deformation, it is intended to shape the seal in the groove using a shaping tool.

[0032] During use, the spring 14 keeps the needle 13 pressed against the seat 120, as shown in [Fig. 5], the contact being established between the stop face 132 and the seat 120. The inlet 10 receives the pressurized gas from the regulator 30, for example hydrogen at a pressure of 50 bars. The seal 16 is sufficiently compressed to obtain a gas seal between the inlet 10 and the outlet 11. The gas enters between the bottom face 1300 and the base face 160 and thus tends to increase the diameter of the seal 16, which contributes to improving the seal by pressing it against the seat 120.

[0033] At the start of the opening, as shown in [Fig. 3], the coil is actuated to move the armature 150 and the needle 13 against the spring 14, to the left of [Fig. 3]. The gas can then pass between the nipple 133 and the cylindrical part of the inlet 10 in the clearance between the two and then go towards the outlet 11. The flow is quite low and calibrated by the clearance between nipple 133 and inlet 10.

[0034] By continuing the stroke of the needle 13, the nipple 133 disengages from the inlet 10 in the open position and leaves a passage for the gas between its end and the seat 120. Due to the flared shape of the seat 120, the more the needle 13 moves against the spring 14 under the action of the coil, the more the passage section increases and the more the gas flow rate increases. The open position shown in [Fig.4] is thus reached.

[0035] By releasing the action of the coil, the needle 13 returns to the closed position as shown in [Fig.5], under the effect of the spring 14.

[0036] The nipple 133 has for example a diameter of 2.5 mm and the seal 16 a diameter of 3.5 mm. The total stroke of the needle 13 is for example 3 mm. The pressing force provided by the spring 14 of the needle 13 against the seat 120 is between 40 and 50 N.

[0037] In a second embodiment, the seal 16' is toric with a circular section, as shown in [Fig.7]. The seal 16' is placed in the same circular groove 130 as described previously, with adapted dimensions. The operating mode remains identical.

[0038] In a third embodiment, the 16” seal is toric with a D-shaped section, the straight part 160” of the section being oriented along the axis A of the torus and on the inside of the torus, as shown in [Fig.8]. The 16” seal is placed in the same circular groove 130 as previously described, with adapted dimensions. The operating mode remains identical.

[0039] The seal 16 is for example made of a material comprising polytetrafluoroethylene (PTFE). Alternatively, the seal 16 is made of an elastomeric material having a Shore A hardness of 60 to 90, for example comprising ethylene-propylene-diene monomer (EPDM).

[0040] The choice of one or other of the materials is made according to the desired hardness, the expected temperature range, the ease of implementation, the service life or other parameters.

Claims

Claims

1. Actuated valve for regulating the flow of a gas, the valve comprising - a body (12) comprising an inlet (10) and an outlet (11) for the gas and a seat (120) between the inlet (10) and the outlet (11), the seat (120) being flared; - a needle (13) of which a first end (131) comes into contact with the seat (120) in a closed position by the support of a spring (14); - an actuator (15) tending to detach the needle (13) from the seat (120) towards an open position against the spring (14) characterized in that the needle (13) comprises a circular groove (130) containing a flexible seal (16, 16', 16”) bearing against the seat (120) in the closed position.

2. Valve according to one of the preceding claims, in which the circular groove (130) comprises a bottom face (1300) of cylindrical shape with the same axis as the axis of the needle (13), and two flanks extending radially from the bottom face (1300), of which a first flank (1301) is on the side of a tip of the needle (13) and a second flank (1302) is opposite the first flank (1301).

3. Valve according to claim 2, in which the seal (16) has a substantially polygonal section with a base face (160) facing the bottom face (1300), a first flank face (161) facing the first flank (1301), a second flank face (162) facing the second flank (1302) and a seat face (163) facing the seat (120).

4. A valve according to claim 5, wherein the base face (130) of the seal (16) is inclined relative to the longitudinal axis in the sense that the direction of the base face (130) is concurrent with the axis of the needle (13) opposite the first end (131).

5. Valve according to one of claims 1 or 2, in which the seal (16') is toric with a circular section.

6. Valve according to one of claims 1 or 2, in which the seal (16”) is toric with a D-shaped section, the straight part (160”) of the section being oriented along the axis (A) of the torus and on the inside of the torus.

7. Valve according to one of the preceding claims, in which the seal (16, 16', 16”) is made of a material comprising a component from the group comprising polytetrafluoroethylene (PTFE) and ethylene-propylene-diene monomer (EPDM).

8. Valve according to one of the preceding claims, in which the needle (13) comprises at its first end (131) a stud (133) which is inserted in a fitted manner into the inlet (10) in the closed position, the stud (133) being disengaged from the inlet (10) in the open position.

9. Valve according to claim 8, in which the radial clearance between the nipple (133) and the inlet (10) is between 1 and 10 μm.

10. Valve according to one of the preceding claims, in which the needle (13) comprises a stop face (132) for limiting the travel of the needle (13) in the closed position by being in contact with the seat (120).

11. Valve according to one of the preceding claims, in which the spring (14) is dimensioned to provide a pressing force of the needle (13) against the seat (120) of between 35 and 50 N.

12. Gas supply system for a consumer (2), such as a heat engine or a fuel cell, the system comprising a gas tank (3) connected to a regulating device comprising a valve (1) according to one of the preceding claims, the inlet (10) of the valve (1) being connected on the side of the tank (3), the outlet (11) being connected on the side of the consumer (2).

13. A system according to claim 12, wherein the fuel is hydrogen stored under pressure in the tank (3), the system further comprising a pressure reducer (30) at the outlet of the tank (3) for reducing the gas to a target pressure of 25 to 50 bars, the valve enabling the gas to be delivered to the outlet at a regulated pressure of between 5 and 40 bars.

Images