Shut-off valve and fuel gas tank with shut-off valve

Abstract

The invention relates to a shut-off valve (1) for a fuel gas tank, comprising a main valve (2) and a control valve (3), wherein the main valve (2) has a valve piston (5) movably mounted in a valve housing (4), which interacts with a valve seat (6) formed in the valve housing (4), and wherein the control valve (3) has a control piston (7) arranged coaxially with the valve piston (5), which is movably movable and interacts with a sealing seat (8) formed in the valve piston (5) for opening and closing a drain restrictor (9) formed in the valve piston (5). According to the invention, the drain restrictor (9) has a diffuser section (10) mediating between an inlet diameter (D1) and a correspondingly larger outlet diameter (D2), which is conical and / or stepped. The invention further relates to a fuel gas tank with a shut-off valve (1) according to the invention.

Description

[0001] The invention relates to a shut-off valve for a fuel gas tank. Furthermore, the invention relates to a fuel gas tank with a shut-off valve according to the invention.

[0002] A preferred application area of ​​the invention is vehicles that are powered by a fuel gas which is kept on board the vehicle in a fuel gas tank. State of the art

[0003] Mobile fuel gas tank systems are known to exist, consisting of at least one fuel gas tank for storing fuel gas, such as hydrogen or natural gas. These fuel gas tanks are typically designed as high-pressure tanks. A high-pressure tank always requires a shut-off valve to seal the tank tightly when the vehicle is not in operation. For safety reasons, the shut-off valve is designed as a normally closed (NC) valve.

[0004] German patent application DE 10 2021 205 684 A1 discloses, by way of example, a two-stage opening solenoid valve functioning as a shut-off valve for hydrogen tank systems. This valve comprises a main valve and a control valve for controlling the main valve. The main valve has a valve piston that is movably mounted back and forth in a valve housing and interacts with a valve seat formed in the valve housing. The control valve has a control piston arranged coaxially with the main valve piston and also movable back and forth. This control piston interacts with a sealing seat formed in the main valve piston to open and close a flow restrictor formed in the main valve piston. The movements of the control piston, which are controlled by a solenoid coil, allow for the variation of a control pressure in a control chamber, which is limited by the main valve piston.

[0005] The opening of the main valve is thus controlled via the control pressure in the control chamber. To close it, the current to the solenoid coil is cut off, so that the control piston of the control valve is first returned to its sealing seat by the spring force of a spring. At the same time, the outlet throttle is closed again, and the control chamber is filled with gas via an inlet throttle until the pressure in the control chamber is the same as the pressure in front of the valve seat of the main valve, whereupon the main valve also closes.

[0006] For rapid opening of the main valve, a drain restrictor with the largest possible cross-sectional area is advantageous. However, in the closed position, a large cross-sectional area exerts a closing force on the control piston of the control valve due to the pressure difference between the tank and system pressure. Therefore, the magnetic force required to open the control valve, or the size of the solenoid coil, increases with the size of the throttle cross-section. However, this is limited by installation space constraints, thus also limiting the opening dynamics.

[0007] The present invention is concerned with the objective of providing a shut-off valve for a tank valve which has improved opening dynamics.

[0008] The problem is solved by the shut-off valve with the features of claim 1. Advantageous embodiments of the invention are described in the dependent claims. Furthermore, a fuel gas tank with a shut-off valve according to the invention is described. Disclosure of the invention

[0009] The proposed shut-off valve for a fuel gas tank comprises a main valve and a control valve. The main valve has a valve piston movably mounted back and forth in a valve housing, which interacts with a valve seat formed in the valve housing. The control valve has a control piston arranged coaxially with the valve piston and movable back and forth, which interacts with a sealing seat formed in the valve piston to open and close a drain restrictor formed in the valve piston. According to the invention, the drain restrictor has a diffuser section mediating between an inlet diameter and a correspondingly larger outlet diameter, which is conical and / or stepped.

[0010] The flow coefficient of a throttle and thus its effective diameter D effThey are based on the pressure loss generated within the throttle geometry, that is, on the pressure loss coefficient ζ. The following equation applies, where D is the geometric diameter at the throttle inlet: Deff∝Dς

[0011] The majority of the pressure loss occurs at the throttle outlet due to the sudden transition to a much larger flow cross-section. The entire dynamic pressure component of the flow is converted into heat during this transition (ζ→1).

[0012] To reduce pressure loss, the outlet throttle of a shut-off valve according to the invention features a gradual, rather than a sudden, transition from an inlet diameter to a correspondingly larger outlet diameter. This gradual transition is achieved by a diffuser section that is conical and / or stepped. Due to the gradual transition, the dynamic pressure is largely maintained or converted into a static pressure. This results in a significantly reduced pressure loss and a smaller effective diameter D. eff The flow restrictor is significantly increased. The increase in the effective diameter D effThe reduced flow rate is achieved without increasing the pressure forces acting on the control piston of the control valve when closing, so the required opening force remains unchanged. This means that the solenoid coil does not need to be larger to achieve improved opening dynamics. Furthermore, the advantages of the proposed throttle geometry can be used to reduce the pressure forces acting on the control piston when closing, while maintaining the same opening dynamics. This saves installation space, as overcoming the closing pressure forces requires lower magnetic forces, thus allowing for a smaller solenoid coil.

[0013] If the transition from the inlet diameter to the correspondingly larger outlet diameter occurs via a conically designed diffuser section of the flow restrictor, a flow coefficient ζ of almost 0 can be achieved. This means that the pressure loss is also approximately 0.

[0014] If the transition from the inlet diameter to the correspondingly larger outlet diameter occurs via a stepped diffuser section, this section is preferably designed with multiple steps. This is because, with an increasing number of steps, the geometry of the diffuser section approaches the shape of a cone, so that the pressure loss decreases as the number of steps increases. However, even if the transition occurs via only two steps, a large portion of the dynamic pressure can be retained via the diffuser section, or the pressure loss can be significantly reduced.

[0015] Advantageously, the diffuser section in the area of ​​the first of two stages experiences a maximum area increase of 100%. This means that the first stage mediates between a first diameter and a second diameter, which generates an area that is at most twice as large. In this way, the pressure loss within the throttle can be halved.

[0016] Furthermore, it is proposed that the outlet restrictor opens into a control chamber via the inlet diameter. This means that the inlet diameter faces the control chamber and the outlet diameter faces away from it. When the control valve is open, gas flows from the control chamber into the outlet restrictor via the inlet diameter and out of the outlet restrictor via the outlet diameter. Preferably, the control chamber is connected via an inlet restrictor to a valve chamber where tank pressure prevails, i.e., the same pressure as in the fuel gas tank. The control chamber can thus be refilled with gas via the inlet restrictor, with this gas being drawn from the fuel gas tank.

[0017] The proposed shut-off valve is preferably electromagnetically actuated. This means that the shut-off valve includes a solenoid coil which, when energized, generates a magnetic field whose magnetic force acts in the opening direction to provide the necessary opening force by which the control piston of the control valve is lifted from its sealing seat. Electromagnetic actuation is simple and cost-effective to implement.

[0018] Furthermore, a fuel gas tank with a shut-off valve according to the invention is proposed. The fuel gas tank can be, in particular, a hydrogen or natural gas tank. The shut-off valve allows fuel gas to be withdrawn from the fuel gas tank. The design of the shut-off valve as a normally closed valve ensures that no fuel gas can escape uncontrollably from the fuel gas tank.

[0019] In a further development of the invention, it is proposed that the shut-off valve, together with at least one other valve, forms a tank valve assembly inserted into the fuel gas tank. Additional safety functions can be implemented via the at least one other valve, for example, manual venting of gas from the fuel gas tank in the event of a defect or accident. The combination of the valves into a tank valve assembly simplifies assembly and helps to save installation space. The tank valve assembly can also include further components, for example, a filter and / or a sensor. Drawings

[0020] The invention and its advantages are explained in more detail below with reference to the accompanying drawings. These show: Fig. 1 a schematic longitudinal section through a shut-off valve according to the invention for a fuel gas tank, Fig. 2 a schematic longitudinal section through the drain throttle of the shut-off valve of the Fig. 1, Fig. 3 a schematic longitudinal section through the drain throttle of a shut-off valve according to the invention in a second preferred embodiment, Fig. 4 a schematic longitudinal section through the drain throttle of a shut-off valve according to a third preferred embodiment and Fig. 5 a schematic longitudinal section through the drain throttle of a shut-off valve according to a fourth preferred embodiment according to the invention. Detailed description of the drawings

[0021] The Fig. Figure 1 shows an exemplary shut-off valve 1 according to the invention for a fuel gas tank. The shut-off valve 1 comprises a main valve 2 and a control valve 3. The main valve 2 has a valve piston 5 that interacts with a valve seat 6, the valve seat 6 being formed by a valve housing 4. The control valve 3 has a control piston 7 that interacts with a sealing seat 8, the sealing seat 8 being formed by the valve piston 5. A release throttle 9 formed in the valve piston 5 can be released via the sealing seat 8 to reduce the control pressure in a control chamber 12, which exerts a closing force on the valve piston 5 of the main valve 2. If this force decreases, the main valve 2 can open.Simultaneously, the control chamber 12 fills with gas via an inlet throttle 13. The throttle cross-sections of the inlet throttle 13 and the outlet throttle 9 are matched so that the pressure in the control chamber 12 can drop sufficiently to allow the main valve 2 to open. With the sealing seat 8 closed or the outlet throttle 9 closed, the control chamber 12 fills with gas, exerting a closing force on the valve piston 5 that closes the main valve 2. For this purpose, the inlet throttle 13 is connected to a valve chamber 14, which is pressurized by the tank.

[0022] In the Fig. 2 is the drain throttle 9 of the shut-off valve 1 of the Fig. Figure 1 is shown enlarged. On the control chamber side, the outlet throttle 9 has an inlet diameter D1 of 200 µm, which widens via a diffuser section 10 to an outlet diameter D2 of 500 µm. Since the diffuser section 10 is conical, the transition from D1 to D2 is not abrupt, but gradual. In this way, the pressure loss within the outlet throttle 9 can be reduced to almost zero. This means that a pressure loss coefficient ζ of almost zero is achieved.

[0023] The Fig. Figure 3 shows a flow restrictor 9 with a modified restrictor geometry. The inlet diameter D1 is again 200 µm and widens to an outlet diameter D2 of 500 µm. The transition occurs gradually via a diffuser section 10, which is both conical and stepped. A conical diffuser section 10 follows the inlet diameter D1, widening to a diameter D3 of 400 µm. The transition to the outlet diameter D2 then occurs via a step 11. Due to the small widening in the area of ​​step 11, the pressure loss can also be kept low here. The pressure loss coefficient ζ is also approximately 0.

[0024] Another modification is in the Fig. Figure 4 shows that the inlet diameter D1 of 200 µm widens via a multi-stage diffuser section 10 to an outlet diameter D2 of 500 µm. A total of two stages 11 are formed, with the first diameter step increasing the area by no more than 100%. The pressure loss is still significantly reduced, achieving a pressure loss coefficient ζ of 0.35.

[0025] The greater the number of stages (11), the lower the pressure loss. Fig. Figure 5 shows an example of a flow restrictor 9 with an inlet diameter D1 of 200 µm and an outlet diameter D2 of 500 µm, in which a gradual transition is created by means of a four-stage diffuser section 10. The four-stage design results in an approximately conical geometry, so that here too a pressure loss or pressure loss coefficient ζ of approximately 0 is achieved. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 205 684 A1

[0004]

Claims

[1] Shut-off valve (1) for a fuel gas tank, comprising a main valve (2) and a control valve (3), wherein the main valve (2) has a valve piston (5) movably mounted in a valve housing (4) which interacts with a valve seat (6) formed in the valve housing (4), and wherein the control valve (3) has a control piston (7) arranged coaxially to the valve piston (5) which moves back and forth and interacts with a sealing seat (8) formed in the valve piston (5) for releasing and closing a drain throttle (9) formed in the valve piston (5), characterized by , that the flow restrictor (9) has a diffuser section (10) mediating between an inlet diameter (D1) and a correspondingly larger outlet diameter (D2), which is conical and / or stepped. [2] Shut-off valve (1) according to claim 1, characterized by , that the diffuser section (10) of the drain throttle (9) is designed in multiple stages. [3] Shut-off valve (1) according to claim 1 or 2, characterized by , that the diffuser section (10) in the area of ​​a first of two stages (11) experiences a maximum area increase of 100%. [4] Shut-off valve (1) according to any one of the preceding claims, characterized by , that the outlet throttle (9) opens via the inlet diameter (D1) into a control chamber (12) which is preferably connected via an inlet throttle (13) to a valve chamber (14) in which tank pressure prevails. [5] Shut-off valve (1) according to any one of the preceding claims, characterized by , that the shut-off valve (1) is electromagnetically actuated. [6] Fuel gas tank with a shut-off valve (1) according to one of the preceding claims. [7] Fuel gas tank according to claim 6, characterized by , that the shut-off valve (1) together with at least one other valve forms a tank valve assembly inserted into the fuel gas tank.

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