Method and apparatus for calculating the prevailing pressure in a tank - Patents.com

Abstract

A method (20) for calculating the tank pressure prevailing in a tank, characterized in that a voltage (10) is applied (21) to a solenoid coil of a solenoid valve closing the tank, a current (11) flowing through the solenoid coil is measured (22) until a return (13) of the current (11) characterizing the opening (12) of the solenoid valve is recorded, and the tank pressure is calculated (23) using the current (11) measured during the return (13).

Description

[Technical field]

[0001] The present invention relates to a method for calculating the prevailing pressure in a tank.The invention further relates to a corresponding device, a corresponding computer program as well as a corresponding storage medium. [Background technology]

[0002] In prior art hydrogen-powered vehicles, pressure tanks are used that are made, for example, of carbon fiber reinforced plastic and can withstand tank pressures of up to 800 bar. The resulting accumulator density gives this type of vehicle a driving range of more than 500 km.

[0003] Patent document 1 discloses an electromagnetic shut-off valve with particular application for opening and closing a pressurized hydrogen reserve tank. According to one embodiment, the valve has two valve sealing elements, one side of which is located on the high pressure side of the valve and the other side of which is located on the high pressure side of the valve. Thus, the pressures applied to the two valve sealing elements are compensated so that only a small force is required to open the valve against the high pressure.

[0004] Furthermore, so-called directly controlled solenoid valves are known, the driving force of which acts directly on a sealing element in the form of a needle-shaped valve piston. When the solenoid is switched off, a compression spring presses the valve piston against the valve seat, thereby keeping the valve closed. The flow direction of the medium flowing through the valve is defined in such a way that when the valve is closed, the pressure difference occurring between the inlet and the outlet of the valve additionally presses the valve piston against the valve seat. To open the valve, the piston must be lifted off the valve seat exclusively by the electromagnetic drive, i.e. the drive must work against the compression spring and against the pressure difference applied to the valve piston. The minimum solenoid drive force required to open such a type of valve depends, inter alia, on the spring force, the size of the valve seat and the maximum pressure difference at the closed valve. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] German Patent Publication No. 102006027712 Summary of the Invention

[0006] The invention provides a method for calculating the prevailing pressure in a tank, a corresponding device, a corresponding computer program as well as a corresponding storage medium as set forth in the independent claims.

[0007] The proposed method is based on the knowledge that in compressed gas tanks in mobile applications, for example in hydrogen tank systems, shut-off valves are used in the usual way: in the stationary state, this valve is closed, thereby sealing the tank, and during operation, the valve is open, thereby allowing gas to be removed to fuel the drive system.

[0008] Such a shut-off valve can be constructed, for example, as a magnetically controlled regulating valve of the above-mentioned construction type. In the stopped state, the valve is closed, in which case the spring presses the valve body against the valve seat as described above, thereby sealing the tank container. To open the valve during operation, a voltage is applied to the magnetic coil. The magnetic force thus generated overcomes the spring and compression forces acting in the closing direction, thereby opening the valve.

[0009] The method according to the invention furthermore takes into account the requirement to measure the gas temperature and pressure in the tank container in order to control or monitor the state of the tank container. However, in conventional tank systems with several tank containers, pressure sensors are sometimes not provided in all containers. Rather, only one high-pressure sensor is installed in the high-pressure line, which measures the pressure in the high-pressure line. During operation, when the tank valves of all tank containers are open, the pressure in the tank containers can be calculated or at least estimated from the pressure measured in the high-pressure line. However, before the tank valves are opened, for example when starting the vehicle, the pressure in the tank containers without a pressure sensor is unknown. This is particularly disadvantageous when different pressures prevail in the individual tank containers at the time of starting. In such a situation, due to a large pressure difference between the tank container and the high-pressure line, many tank valves will be opened late, which can lead to an overall delay in starting the vehicle.

[0010] In contrast, the method described below opens the tank valves in a predetermined sequence when the vehicle is started while the tank valves are still closed by knowing the pressure in the individual tank containers, thereby allowing the tank system to operate without any problems.

[0011] The measures set out in the dependent claims make it possible to realize advantageous embodiments and developments of the basic idea set out in the independent claims. It is also possible to know the pressure in the individual tank containers at start-up without a pressure sensor in order to calculate the exact filling level of the fuel in the respective tank container.

[0012] According to another aspect, a software function may be provided for calculating the pressure in the tank vessel, which is not fitted with a pressure sensor, before the tank valve configured as a magnetically controlled shut-off valve is opened. This function may partially provide a pressure sensor in the tank vessel in order to allow unhindered opening of the tank system as well as calculation of the fill level of the tank system during start-up. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 shows the return of the current through the electromagnetic coil, which marks the opening of the solenoid valve. [Diagram 2] 2 is a flowchart of a method according to a first embodiment. [Diagram 3] FIG. 11 is a schematic diagram of a control unit according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description.

[0015] Figure 1 illustrates the return (13) of current (11) through the electromagnetic coil, which marks the opening (12) of a shut-off solenoid valve. In the closed state of the shut-off valve, spring and compression forces predominate, pressing the valve disc against the valve seat. When a voltage (10) is applied to the electromagnetic coil, a magnetic force is generated. As soon as the magnetic force overcomes the spring and compression forces, the valve begins to open.

[0016] The time of this first valve disc stroke can be seen in the diagram shown in Figure 1 by a bend in the graph of the current strength (11). At this point, the compression force can be calculated from the spring force, pressure and magnetic force profile. The spring force is basically known as a design value, and the magnetic force can be calculated from the parameters of the electromagnetic coil and the current (11). The tank pressure can then be calculated from the compression force calculated in this way and the pressure measured in the high-pressure line.

[0017] Based on this interaction, the starting of a hydrogen-powered vehicle can be optimized, especially if the vehicle has several tanks connected by a common pressure line. These tanks are filled with fuel of different volumes and are closed by solenoid valves. This use case is explained with the aid of the flow chart in Fig. 2.

[0018] First, a predetermined voltage (10-Fig. 1) is applied to the solenoid coil of each solenoid valve (process 21), and the current (11-Fig. 1) flowing through the solenoid coil is measured (process 22) until the return (13) of the current (11-Fig. 1), which indicates the stroke movement of the valve disc caused against the spring force exerted by the valve spring and characterizes the opening (12-Fig. 1) of the solenoid valve, is recorded. Also, the line pressure prevailing in the common pressure pipe is measured once by a pressure sensor provided for this purpose.

[0019] Using the current through the coil (11-figure 1) measured during return (13-figure 1) on the one hand and the spring force of the spring biasing the valve, which is structurally limited and therefore generally known, on the other hand, the pressure difference between the respective tank and the pressure line is calculated, from which the tank pressure can be derived directly taking into account the known line pressure (process 23). From the tank pressure calculated in this way, the filling level of the fuel in the respective tank can be estimated or a sequence of opening of the solenoid valve (12-figure 1) can be defined for the purpose of supplying fuel to a fuel cell or a motor.

[0020] The method (20) may be implemented, for example, in software or hardware or in a mixed form consisting of software and hardware, for example in a control unit (30), as shown in the schematic diagram of FIG. [Explanation of symbols]

[0021] 10 Voltage 11 Electric current, current strength 12 open 13 Return 20 ways 21 Process, application 22 Process, Measurement 23 Process, Calculation 30 Device, control unit

Claims

1. A method (20) for calculating a prevailing tank pressure in a tank, comprising: - applying a predetermined voltage (10) to the solenoid coil of the solenoid valve that closes the tank (21); - measuring (22) the current (11) flowing through the electromagnetic coil until a return (13) of said current (11) is recorded, which characterizes the opening (12) of said solenoid valve, - calculating (23) the tank pressure using the current (11) measured during the recovery (13), - the solenoid valve is biased by a valve spring, - further performing said calculation (23) using the structurally limited spring force applied by said valve spring, - connecting the tank to a pressure line by means of the solenoid valve, - measuring the prevailing line pressure in said pressure line; - said calculation (23) is carried out by first calculating the pressure difference between said tank and said pressure line and then calculating said tank pressure from this pressure difference and said line pressure, 1. A method (20) for calculating a prevailing tank pressure in a tank, comprising:

2. - applying the spring force to the valve element of the solenoid valve; - the return (13) is performed during the stroke movement of the valve disc, The method (20) of claim 1 ,

3. - connecting said pressure line to another tank by another solenoid valve, - carrying out said method (20) in each of said tanks one after the other, 3. The method (20) according to claim 1 or 2, characterized in that

4. - filling said tank at least partially with fuel, - estimating the fuel filling level in each of the tanks from the calculated tank pressures do, The method (20) of claim 3, characterized in that

5. - using said fuel to power a vehicle; - opening (12) of the solenoid valves of the tanks when starting the vehicle in succession each depending on the calculated tank pressure, The method (20) of claim 4, characterized in that

6. A computer program, designed to carry out the method (20) according to claim 1 or 2.

7. 7. A machine-readable storage medium having the computer program of claim 6 stored therein.

8. An apparatus (30) designed for carrying out the method (20) according to claim 1 or 2.

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