Valve assembly for a fuel gas tank, fuel gas tank comprising a valve assembly

Abstract

The invention relates to a valve assembly (1) for a fuel gas tank (2), comprising a base body (3) in which an extraction path (4) with integrated shut-off valve (6) for extracting fuel gas from the fuel gas tank (2) and a refuelling path (5) with integrated non-return valve (7) for refuelling the fuel gas tank (2) with fuel gas are formed, wherein the extraction path (4) and the refuelling path (5) are brought together within the base body (3) in a path (9) which opens into a common gas connection (8). According to the invention, the transition of the refuelling path (5) into the path (9) is designed as a cross-sectional constriction (10) and the extraction path (4) is connected in the area of the cross-sectional constriction (10).

Description

[0001] Description

[0002] Valve assembly for a fuel gas tank, fuel gas tank with valve assembly

[0003] The invention relates to a valve assembly for a fuel gas tank. Furthermore, the invention relates to a fuel gas tank with a valve assembly according to the invention. The fuel gas can, in particular, be hydrogen or natural gas, which is stored under pressure in a fuel gas tank.

[0004] The preferred field of application of the invention is fuel cell and / or gas vehicles that are powered by a fuel gas.

[0005] State of the art

[0006] Mobile fuel gas tank systems are known, consisting of at least one fuel gas tank for storing fuel gas, such as hydrogen or natural gas. The fuel gas tank is typically designed as a high-pressure tank, particularly a high-pressure gas cylinder. A high-pressure tank always requires a shut-off valve to seal the tank tightly when the vehicle is not in use. For safety reasons, the shut-off valve is usually designed as a normally closed valve.

[0007] The shut-off valve is usually integrated into a valve assembly that enables both the withdrawal of fuel gas from the fuel gas tank and the refueling of the fuel gas tank with fuel gas. For this purpose, the valve assembly has a base body in which a withdrawal path and a refueling path are formed. A controllable shut-off valve is integrated into the withdrawal path and a check valve is integrated into the refueling path. The check valve prevents fuel gas from escaping from the fuel gas tank via the refueling path. A further check valve can be arranged in the withdrawal path so that the flow direction in both paths is determined via the check valves. DE 10 2016 008 443 A1 discloses, by way of example, a tank valve for mounting on a compressed gas container. The tank valve has a base body with a gas connection via which the compressed gas container can be refueled on the one hand and gas can be withdrawn from the compressed gas container on the other.Within the base body, the gas connection is divided into a refueling line and a withdrawal line, with a withdrawal valve located in the withdrawal line. A check valve connected in series with the withdrawal valve blocks the flow in the opposite direction to the intended direction when gas is withdrawn. The check valve thus prevents gas from flowing into the compressed gas cylinder via the withdrawal line during refueling. Another check valve is integrated into the refueling line, which opens in the refueling direction and closes in the withdrawal direction.

[0008] The present invention is concerned with the task of preventing reverse flow through the extraction or shut-off valve integrated into the extraction path, even without a check valve in the extraction path. This is intended to create a valve assembly for a fuel gas tank that is as simple as possible in design.

[0009] To achieve this objective, the valve assembly having the features of claim 1 is proposed. Advantageous further developments of the invention are set forth in the subclaims. Furthermore, a fuel gas tank having a valve assembly according to the invention is specified.

[0010] Disclosure of the invention

[0011] The valve assembly proposed for a fuel gas tank comprises a base body in which a withdrawal path with an integrated shut-off valve for withdrawing fuel gas from the fuel gas tank and a refueling path with an integrated check valve for refueling the fuel gas tank with fuel gas are formed. The withdrawal path and the refueling path are combined within the base body in a single path that opens into a common gas connection. According to the invention, the transition from the refueling path to the path is designed as a cross-sectional constriction, and the withdrawal path is connected in the area of ​​the cross-sectional constriction.The cross-sectional constriction and the connection of the extraction path in the area of ​​the cross-sectional constriction form a Venturi nozzle, with the help of which the pressure in the extraction path, specifically in the extraction direction downstream of the shut-off valve, can be reduced to such an extent (“Bernoulli equation”) that the shut-off valve remains safely closed when the fuel gas tank is filled with fuel gas.

[0012] A pressure pi prevails in the fuel gas tank. If no refueling is taking place, and the shut-off valve in the common path is closed, the pressure P2 in the gas connection downstream of the shut-off valve is lower than the pressure pi, so that a pneumatic closing force acts on the shut-off valve. When refueling the fuel gas tank with fuel gas, in order to open the check valve arranged in the refueling path, a refueling pressure PT must be provided at the common gas connection that is at least the opening pressure of the check valve greater than the pressure pi in the fuel gas tank, because otherwise the check valve will not open. This means that there is a risk that the pressure in the withdrawal path downstream of the shut-off valve, hereinafter referred to as pressure P2,sov, will also rise to the refueling pressure PT. This would then result in the shut-off valve arranged in the withdrawal path opening without power, and flow through it in the reverse direction.However, due to the cross-sectional constriction and the connection of the extraction path in the area of ​​the cross-sectional constriction, the pressure P2,sov in the extraction path can be reduced during refueling to such an extent that P2,sov always remains smaller than pi and an unintentional opening of the shut-off valve is prevented.

[0013] The effect of the Venturi nozzle thus replaces a check valve arranged in the extraction path.

[0014] Advantageously, a diffuser is connected to the cross-sectional constriction in the refueling direction. The flow cross-section of the fuel gas is therefore not suddenly increased downstream of the cross-sectional constriction in the refueling direction, but rather a smooth transition is created via the diffuser. This results in less turbulence in the fuel gas flow and greater pressure recovery downstream of the Venturi nozzle, which facilitates the opening of the check valve located in the refueling path. At the same time, the pressure difference between a pressure P2,RSV between the diffuser and the check valve in the refueling path increases, and thus also the pressure difference between the pressure pi in the fuel gas tank and the pressure P2,sov in the withdrawal path.

[0015] The shut-off valve is preferably designed as an electrically controlled and normally closed valve, comprising a valve member that is biased toward a valve seat by the spring force of a closing spring. The shut-off valve is therefore designed as a normally closed valve, thus meeting the requirements for a shut-off valve for fuel gas tanks. As an electrically controlled valve, the shut-off valve can be designed to be particularly compact and robust.

[0016] To open the shut-off valve, a solenoid coil is energized, generating a magnetic force that lifts the valve element out of the valve seat against the force of the closing spring. When the solenoid coil is de-energized, the closing spring presses the valve element into the valve seat. In addition to the closing force of the closing spring, a pneumatic force acts on the valve element via the pressure difference pi-p2,sov. Since a corresponding design of the Venturi nozzle ensures that the pressure P2,sov does not rise above the pressure pi during refueling, the pneumatic force acting on the valve element of the shut-off valve always has a closing effect. A pneumatic force that counteracts the spring force of the closing spring and unintentionally opens the shut-off valve is thus reliably avoided.

[0017] Furthermore, the check valve integrated into the refueling path preferably has a closing spring whose spring force is designed such that the opening pressure of this check valve is lower than the opening pressure of the shut-off valve in the reverse direction. Thus, the pressure difference required to open the check valve is lower than that required to open the shut-off valve in the reverse direction. This measure further reduces the risk of unintentional opening of the shut-off valve.

[0018] Furthermore, it is proposed that the common gas connection be designed as a connecting piece, preferably as a connecting piece with an external thread. The connecting piece facilitates the connection of an external gas line, through which fuel gas can be extracted from the fuel gas tank and fuel gas can be supplied to the fuel gas tank during refueling. If the connecting piece has an external thread, the external gas line can be screwed onto the connecting piece, creating a high-pressure-resistant connection between the gas line and the valve assembly via the screw connection.

[0019] The base body preferably further comprises a connecting section for connection to the fuel gas tank. The valve assembly can be easily mounted on a fuel gas tank via the connecting section. For example, the valve assembly can be inserted into the bottle neck of a fuel gas tank designed as a high-pressure gas cylinder via the connecting section. The connecting section can further comprise an external thread so that it can be screwed into the bottle neck to achieve a high-pressure-resistant connection via the screw connection.

[0020] The further proposed fuel gas tank is characterized by having a valve assembly according to the invention. The valve assembly is preferably inserted into the fuel gas tank in sections, so that the common gas connection is accessible from the outside. Since the extraction path and the refueling path are combined and lead as a single path into the common gas connection of the valve assembly, only one gas line needs to be connected for extracting fuel gas and for refueling the fuel gas tank with fuel gas. The Venturi nozzle integrated into the paths prevents accidental opening of the shut-off valve arranged in the extraction path during refueling, so that the extraction path does not need to be protected by an additional check valve.

[0021] A preferred embodiment of the invention is explained in more detail below with reference to the accompanying drawing. This shows a schematic representation of a valve assembly according to the invention for a fuel gas tank.

[0022] Detailed description of the drawing

[0023] The illustrated valve assembly 1 according to the invention serves to withdraw fuel gas from a fuel gas tank 2 and to refuel the fuel gas tank 2 with fuel gas, in particular with hydrogen or natural gas. The illustrated valve assembly 1 has a base body 3 with a connecting section 16, via which the valve assembly 1 is connected to the fuel gas tank 2. At the other end, the base body 3 forms a gas connection 8 for connecting an external gas line (not shown). Formed in the base body 3 are a withdrawal path 4, a refueling path 5, and a path 9, via which the withdrawal path 4 and the refueling path 5 are joined. The path 9 opens into the common gas connection 8.

[0024] Integrated into the extraction path 4 is a shut-off valve 6, which is electrically controllable and designed as a normally closed valve. The shut-off valve 6 has an axially movable valve member 12, which is biased toward a valve seat 13 by the spring force of a closing spring 14. The shut-off valve 6 ensures that no fuel gas can escape from the fuel gas tank 2, even in the event of a fault.

[0025] A check valve 7 with a closing spring 15 is integrated into the refueling path 5, via which the opening force of the check valve 7 is predetermined. The check valve 7 opens in the refueling direction against the spring force of the closing spring 15 (see arrow 17). During refueling, a pressure P2,RSV prevails upstream of the check valve 7 in the refueling direction, which is slightly lower than a refueling pressure PT at the common gas connection 8, but greater than a pressure pi in the fuel gas tank 2, wherein the pressure difference causes a pneumatic force opening the check valve 7, which is greater than the spring force of the closing spring 15, so that the check valve 7 opens.

[0026] To prevent the shut-off valve 6 arranged in the extraction path 4 from opening accidentally when refueling the fuel gas tank 2 with fuel gas, the refueling path 5 has a cross-sectional constriction 10, in the area of ​​which the extraction path 4 is connected. The cross-sectional constriction 10 forms a Venturi nozzle, which ensures that in the extraction path 4, downstream of the shut-off valve 4 in the extraction direction, a pressure P2,sov prevails that is always lower than the pressure pi in the fuel gas tank 2. This is because, in the area of ​​the cross-sectional constriction 10, an increased flow velocity occurs when refueling the fuel gas tank 2 with fuel gas, causing the static pressure there to drop ("Bernoulli equation"), so that the pressure P2,sov in the extraction path 4 drops accordingly. The Venturi nozzle thus prevents the shut-off valve 4 from opening accidentally.To increase this effect, a diffuser 11 is formed downstream of the cross-sectional constriction 10 in the refueling direction, so that the flow cross-section in the refueling path 5 is not raised suddenly, but gradually.

[0027] A valve assembly according to the invention may comprise additional valves and / or components in addition to the valves shown. For example, a manual shut-off and / or blow-off valve, a thermal and / or pressure-controlled safety valve, and a temperature and / or pressure sensor may be integrated into the valve assembly.

Claims

Claims 1. Valve assembly (1) for a fuel gas tank (2), comprising a base body (3) in which a withdrawal path (4) with an integrated shut-off valve (6) for withdrawing fuel gas from the fuel gas tank (2) and a refueling path (5) with an integrated check valve (7) for refueling the fuel gas tank (2) with fuel gas are formed, wherein the withdrawal path (4) and the refueling path (5) are combined within the base body (3) in a path (9) which opens into a common gas connection (8), characterized in that the transition of the refueling path (5) into the path (9) is designed as a cross-sectional constriction (10) and the withdrawal path (4) is connected in the region of the cross-sectional constriction (10).

2. Valve assembly (1) according to claim 1, characterized in that a diffuser (11) adjoins the cross-sectional constriction (10) in the refueling direction.

3. Valve assembly (1) according to claim 1 or 2, characterized in that the shut-off valve (6) is designed as an electrically controllable and normally closed valve which has a valve member (12) which is acted upon in the direction of a valve seat (13) by the spring force of a closing spring (14).

4. Valve assembly (1) according to claim 3, characterized in that the check valve (7) integrated into the refueling path (5) has a closing spring (15) whose spring force is designed such that the opening pressure of the check valve (7) is smaller than the opening pressure of the shut-off valve (6) in the reverse direction.

5. Valve assembly (1) according to one of the preceding claims, characterized in that the common gas connection (8) is designed as a connecting piece, preferably as a connecting piece with an external thread.

6. Valve assembly (1) according to one of the preceding claims, characterized in that the base body (3) has a connecting section (16) for connection to the fuel gas tank (2).

7. Fuel gas tank (2) with a valve assembly (1) according to one of the preceding Claims, wherein preferably the valve assembly (1) is inserted in sections into the fuel gas tank (2) so that the common gas connection (8) is accessible from the outside.

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