EP1205704A1 - Process for filling a vehicle tank with gas - Google Patents

Abstract

The method involves determining the instantaneous value of a parameter representing the instantaneous state of filling of a vehicle fuel tank (31) during a gas filling using a temperature sensor (33) and a pressure sensor (32) which are arranged in the vehicle fuel tank. An Independent claim is also included for a gas refueling plant.

Description

The invention relates to a method for filling a vehicle tank with Gas according to the preamble of the independent claim.

Gas powered motor vehicles as an alternative to conventional ones Motor vehicles with liquid fuels such as gasoline or Diesel fuels are becoming increasingly important. Nowadays it is typically used as fuel for gas powered vehicles compressed natural gas is used. However, more modern developments are possible also to use gaseous hydrogen as fuel.

In order to achieve a satisfactory range for gas-powered vehicles enable and at the same time the dimensions of the vehicle tank in To keep reasonable limits, the vehicle tanks are usually on filled with high pressures. In the case of natural gas, for example Vehicle tank to a final pressure of about 200 bar based on a Filled reference temperature of 15 ° C. In the case of gaseous hydrogen even higher final pressures, for example 600 bar, are sought, which in primarily due to the lower energy density of hydrogen (compared to Natural gas).

For safe gas refueling, the Outside temperature taken into account. If you assume that the Ultimate pressure at a reference temperature of 15 ° C for natural gas approximately 200 bar should be at an outside temperature of less than 15 ° C refueling should be stopped at a pressure of less than 200 bar to ensure that when the outside temperature rises in the Vehicle tank no excessive pressure is created. Conversely, at an outside temperature of more than 15 ° C up to a final pressure of more be refueled as 200 bar. The vehicle tanks are so designed that even with fluctuations in the outside temperature not an impermissibly high one Pressure in the tank arises, provided the maximum final pressure at the Refueling corresponds to a pressure of 200 bar at the reference temperature of 15 ° C

EP-A-0 653 585, for example, describes a gas refueling method and a corresponding system known that a very simple and especially very quick refueling - comparable to refueling of petrol possible. According to the method proposed there the vehicle tank with a pressure-resistant line to a delivery device connected and the pressurized gas by means of Dispensing device filled from a storage unit in the vehicle tank. First, the permissible for the currently prevailing temperature Final pressure calculated. Then a small amount of gas is put into the vehicle tank filled to equalize the pressure between the vehicle tank and the To effect delivery device. The one in the vehicle tank Initial pressure is in the dispenser after pressure equalization measured and then a certain mass of gas in the Vehicle tank filled. Then the mass flow of the gas is interrupted and again the pressure in the vehicle tank Dispenser measured. These pressure values become a Relationship between the mass of the gas released and the Pressure determined in the vehicle tank. Based on this connection, a Mass of gas calculated so that to fill up the vehicle tank the final pressure must be supplied with at least one further mass of gas. After the calculated mass of gas has been fed to the vehicle tank the mass flow is interrupted again and that in the vehicle tank prevailing pressure in the dispenser is determined. The operations of the Computing an additional mass of gas, supplying this mass of gas and the interruption of the mass flow for pressure determination Repeated several times until the temperature corrected in the vehicle tank Final pressure is reached.

Based on this state of the art, it is a task of Invention, another method for filling a vehicle tank with propose a gas that is even faster and more accurate Refueling allows without making concessions to safety are necessary. The method should also be applicable for very high final pressures be what they are aiming for when refueling with gaseous hydrogen become.

The method for filling a vehicle tank that solves this problem a gas is characterized by the features of the independent claim characterized.

• mit Hilfe einer Sensoreinrichtung, welche in dem Fahrzeugtank angeordnet ist, wird während der Befüllung der momentane Wert einer Kenngrösse bestimmt, welche repräsentativ für den momentanen Füllstand des Fahrzeugtanks ist,
• die Befüllung wird beendet, wenn die Kenngrösse einen vorgebbaren Endwert erreicht hat.

According to the invention, therefore, a method for filling a vehicle tank with a gas is proposed, in which the vehicle tank is connected to a delivery device with a pressure-resistant line and the pressurized gas is filled into the vehicle tank from the storage unit by means of the delivery device. The process includes the following steps:

• with the aid of a sensor device which is arranged in the vehicle tank, the instantaneous value of a parameter which is representative of the instantaneous fill level of the vehicle tank is determined during the filling,
• the filling is ended when the parameter has reached a definable end value.

Since the parameter, which is representative of the current level of the Tanks is determined with the help of a sensor arrangement which in the Vehicle tank itself is arranged, the filling process without Interruption. The interruptions in the mass flow as proposed in EP-A-0-653 585, in each case the current pressure prevailing in the vehicle tank in the dispensing device are no longer necessary in the method according to the invention, because the measurement data required for the parameter is online during the ongoing filling in the vehicle tank can be determined. This will make it The method according to the invention is particularly quick and precise without Security concessions are necessary. Security increases even more so, because the level was determined based on those in the vehicle tank Measurement data is determined. Data can be recorded in the vehicle tank an even more precise determination of the level, so that the allowed Limits for filling can be used optimally because they are be fully utilized without the risk of exceeding the There are security limits.

The final value is preferably the parameter when it is reached the Filling is stopped, regardless of the temperature, that is, it will selected a parameter that independent of the level of the vehicle tank represented by temperature. The parameter is particularly preferred determines the density of the gas in the vehicle tank. For the density of the gas A final value can be specified in the vehicle tank, namely the maximum allowed density or operational density, which is independent of each prevailing outside temperature when filling. The temperature-independent final value for the parameter has the advantage that it a temperature-corrected value for the final pressure is no longer necessary to calculate the fueling.

Another advantageous measure is that first the Parameter is determined before the vehicle tank is filled with gas, so that the current level of the vehicle tank before the start of the Filling is known as the initial value. This initial value is used determined during the refueling the measurement technology in the vehicle tank current level with the data determined in the dispenser to compare. If there are discrepancies in this comparison, this indicates on an error and appropriate countermeasures can be taken to be hit. As is common practice in the dispenser Mass of the gas released recorded by measurement. From the released gas mass is then taking into account the initial value determines a control variable corresponding to the parameter, which The control variable is compared with the characteristic variable, and there is one Error message or canceling the filling if the deviation a specifiable between the parameter and the control variable Limit exceeded.

This measure allows operational safety at Increase gas refueling significantly, because there are two each different determinations of the current fill level of the vehicle tank. On the one hand, it is arranged in the vehicle tank Sensor device the characteristic representative of the current level is determined and on the other hand in the dispenser on the basis of there metrologically recorded mass of the gas emitted that of Characteristic corresponding control variable determined. By the respective Comparing these two sizes, errors in filling, For example, detect leaks early and reliably.

According to a particularly preferred embodiment, the im Sensor device arranged vehicle tank a temperature sensor and a pressure sensor with which the temperature and pressure of the gas in the Tank is measured. From this, the density of the gas is then as Characteristic determined.

The inventive method is suitable for a variety of Gas refueling systems and especially for those with which compressed natural gas or gaseous hydrogen filled in a tank becomes.

Further advantageous measures and preferred configurations of the Invention result from the dependent claims.

Fig. 1:

die wesentlichen Teile einer Gasbetankungsanlage zur Durchführung eines Ausführungsbeispiels des erfindungsgemässen Verfahren sowie einen zu befüllenden Fahrzeugtank in schematischer Darstellung, und

Fig. 2:

ein Flussdiagramm zur Veranschaulichung des Ausführungsbeispiels des erfindungsgemässen Verfahrens.

The invention is explained in more detail below using an exemplary embodiment and the drawing. The schematic drawing, not to scale, shows:

Fig. 1:

the essential parts of a gas refueling system for performing an embodiment of the inventive method and a vehicle tank to be filled in a schematic representation, and

Fig. 2:

a flowchart to illustrate the embodiment of the inventive method.

Fig. 1 shows a schematic representation of the essential parts of a Gas refueling system for carrying out an embodiment of the Method according to the invention, all of which is identified by the reference number 1 is designated. Furthermore, a gas-powered motor vehicle 30 is indicated which has a vehicle tank 31, which is designed as a pressure vessel is. The vehicle tank 31 serves as a storage container for a gaseous one Fuel, for example compressed natural gas or gaseous Hydrogen, which is required for the operation of the motor vehicle 30. It it goes without saying that the vehicle tank 31 is designed such that it can End pressure and the usual safety reserves easily withstands. With the final pressure means the pressure to which the Vehicle tank 31 is filled during refueling. In the case of natural gas, it is for example, it is customary to choose the final pressure so that it corresponds to a pressure of corresponds to approximately 200 bar at a reference temperature of 15 ° C. In the event of the final pressure of hydrogen is usually chosen higher, for example 600 bar based on the reference temperature 15 ° C.

The vehicle tank 31 is connected via a pressure-resistant connecting line 36 an externally accessible filler neck 37 connected here at the Outside of the motor vehicle 30 is arranged.

In the vehicle tank 31, a sensor device is provided, which in the An embodiment described here a pressure sensor 32 and a Includes temperature sensor 33 with which the current pressure and the current Temperature in the vehicle tank 31 can be measured. The sensors 32, 33 are connected via lines 35 to an outside of the vehicle tank 31, but connected in the motor vehicle 30 provided electronics module 34. The Electronics module 34 receives those detected by sensors 32, 33 Measured values and processes them. Furthermore, the electronics module 34 serves Transmission of data to the gas refueling system 1.

The volume of the vehicle tank 31 is stored in a memory 38, which is a constant size. The volume can be about one Signal line are transmitted to the electronics module 34. Of course it is also possible the volume of the vehicle tank 31 directly in the Store electronic module 34.

The gas refueling system 1 shown only with its essential parts comprises a delivery device 2 and a stationary storage unit 3, in the gas for refueling, for example natural gas or gaseous Hydrogen, is stored. Furthermore, one is not shown Compression device is provided, which the storage unit 3 at Refilled with gas as needed. The storage unit usually comprises several storage tanks, here three storage tanks, each of which has one separate pressure-resistant connecting line 4a, 4b or 4c with the Dispenser 2 is connected.

The dispensing device 2 comprises a switching device 5 to which the three connecting lines 4a, 4b and 4c are connected. Of the Switching device 5 extends a pressure-resistant line 7 over Valve, which is preferably designed as a solenoid valve 6, and via a the mass flow meter 8 downstream of the solenoid valve 6 Output 9 of the dispensing device 2. At the output 9 is a pressure-resistant Line 10 connected to the other end with a coupling 11 which is provided with the filler neck 37 of the motor vehicle 30 is connectable.

The delivery device further comprises a communication module 13, a Evaluation and control unit 12 and an operating module 14 Operating module 14, the gas refueling system by appropriate Inputs are put into operation or operated. The operating module 14 further comprises a display unit on which, for. B. the mass of refueled gas or the price of the gas.

The communication module 13 receives data from the electronics module 34 of the motor vehicle 30 and passes this via a signal line to the Evaluation and control unit 12 further. The evaluation and control unit 12 is also connected to the mass flow meter 8 via signal lines as well as with the solenoid valve 6.

The solenoid valve 6 is an electromagnetically operated valve, which by Signals that come from the evaluation and control unit 12 are controlled becomes. The flow connection for the gas can be made by means of the solenoid valve 6 opened between the switching device 5 and the output 9 or are closed, so that by actuating the solenoid valve 6 Filling process can be started or ended.

The mass flow meter 8 is preferably a measuring device based on the Coriolis principle is based. Such Coriolis mass flow meters per se are well known. They measure the mass of the gas which is given when refueling.

The switching device 5 serves one of the connecting lines 4a or 4b or 4c to be connected to line 7. For example, is the Connection line 4a connected to line 7 and drops during the Refueling the pressure in the part of the connecting line 4a Storage tank of the storage unit 3 so far that the mass flow of the Gas is too low, so the switching device 5 to one other storage tank can be switched over by connecting line 7 with the Connection line 4b or 4c is connected.

With regard to further details and embodiments, reference is made here to the cited EP-A-0 653 585, where such gas refueling systems with Exception of the communication module are described in detail.

The communication module 13 receives data, for example measured values or the volume of the vehicle tank 31 from the electronics module 34 of the Motor vehicle 30. For this purpose, the communication module 13 with the Electronics module 34 signal connected. This can be done using a Signal line 23 take place. It is also possible to connect the signal line 23 to the To integrate pressure-resistant line 10, for example the signal line 23 to be arranged on the outside of the line 10. It is also possible to Signal connection between the electronics module 34 and the To design communication module 13 wirelessly, for example by means of Radio or optical methods such as infrared signals.

The method according to the invention is based on using the Sensor device which is arranged in the vehicle tank 31 while to determine the current value of a parameter during filling, which is representative of the current fill level of the vehicle tank 31 is, that is, the current level of the vehicle tank 31 is by Measurements in the vehicle tank 31 itself determined.

An exemplary embodiment of the method according to the invention will now be described below Method with reference to the flow chart shown in FIG. 2 explained in more detail. In this embodiment, the parameter is the Density ρ of the gas used in the vehicle tank 31. This also as Operating density designated characteristic has the advantage that a maximum permissible end value can be specified, which is independent of the prevailing temperature. So it is no longer necessary one of the outside temperature prevailing during refueling dependent pressure at which refueling is terminated. In previously known methods, the temperature-dependent final pressure for the filling z. B. calculated from the isochoric behavior of the gas become. In the method proposed here, a maximum allowed Final value for the density of the gas can be specified, and the filling can then - regardless of the prevailing outside temperature - continue until this final value for the density in Vehicle tank 31 is reached.

When filling, the one that is currently in the vehicle tank is constantly changing Density of the gas determined. In terms of operational security, it is particularly advantageous, this density in each case in two different ways to determine, namely on the one hand with the help of the measured values of the Vehicle tank 31 arranged sensors 32,33 and on the other hand with the help the gas mass dispensed by the dispenser 2, which by means of of the mass flow meter 8 is measured in the dispensing device 2. If these two values for the density deviate more than a specifiable one Limit value from each other, this indicates an error. For example, a leak or one of the sensors may have occurred 32.33 is not working properly. By means of these two Determination of the density can also be dangerous conditions, such as for example, overfilling of the vehicle tank 31 can be avoided.

The following applies to the density ρ _{T of} the gas in the vehicle tank 31: ρ T = m T / V where m _T denotes the mass of the gas in the vehicle tank 31 and V the volume of the vehicle tank 31, which is a constant variable.

On the other hand, it follows from the gas equation m T / V = p T / (Z * R * T T ) where p _T denotes the pressure in the tank, z the real gas factor, which is a gas-specific variable that is dependent on pressure and temperature, R the general gas constant and T _T the temperature of the gas in the tank. By measuring the temperature T _T and the pressure p _T in the vehicle tank 31 by means of the temperature sensor 33 and the pressure sensor 32, the instantaneous density ρ _T in the vehicle tank 31 can then be determined. The respective value for the real gas factor z can be taken, for example, from a stored table as a function of the pressure and the temperature.

For the refueling of the motor vehicle 30, the pressure-resistant line 10 of the dispensing device 2 is connected to the filler neck 37 of the motor vehicle 30 by means of the coupling 11. Furthermore, the signal line 23 is optionally connected on the one hand to the electronics module 34 and on the other hand to the communication module 13. Before the vehicle tank 31 is filled with gas, the pressure sensor 32 or the temperature sensor 33 first measures the initial pressure p ₀ or the initial temperature T ₀ that prevail in the vehicle tank 31 before the start of filling (step 101 in FIG. 2 ). The density ρ ₀ is then determined in step 102 from p ₀ , T ₀ and the corresponding value for the real gas factor z as an initial value. ρ ₀ indicates the current density of the gas in the vehicle tank 31 before the start of filling. The electronics module 34 transmits the value of ρ ₀ and the volume V of the vehicle tank 31 to be filled to the communication module 13 of the dispensing device 2.

In the dispensing device 2, preferably in the evaluation and control unit 12, the volume V of the vehicle tank 31 and the initial value ρ _{0 become} the initial mass m _{0 of} the gas in the vehicle tank 31 according to the relationship m 0 = ρ 0 · V certainly. The initial value m ₀ thus indicates the mass of the gas that is present in the vehicle tank 31 before the start of filling.

The filling process now begins in step 103 (FIG. 2). The evaluation and control unit 12 opens the solenoid valve 6 and the gas can flow from the storage unit 3 through the mass flow meter 8, the pressure-resistant line 10 and the connecting line 36 into the vehicle tank 31. During the filling process, the pressure sensor 32 and the temperature sensor 33 continuously or at short intervals measure the current pressure p _T or the current temperature T _T in the vehicle tank 31 (step 104). From these two values, the current value ρ _T for the density of the gas in the vehicle tank 31 is determined in step 105 in accordance with the relationship given further above and transmitted to the dispensing device 2.

During the filling process, the mass m _{G of} the released gas is continuously measured in the dispensing device 2 by means of the mass flow meter 8 (step 106). This is done, for example, at a rate of about a hundred pulses (measurements) per kilogram of gas released. In step 107, the evaluation and control unit 12 of the dispensing device 2 uses the volume V of the vehicle tank 31, the initial mass m _{0 of} the gas in the vehicle tank and the current value of the mass m _{G of} the dispensed gas to determine a comparison value ρ _m as a control variable for the Density of gas in the vehicle tank according to the relationship ρ m = (m 0 + m G ) / V

In step 108, the control variable ρ _m is then compared with the density ρ _T determined in the vehicle tank 31. If the deviation between the control variable ρ _m and the density ρ _T determined in the vehicle tank exceeds a predeterminable limit value D, the filling is terminated (step 110) and / or an error warning is given. Otherwise, it is checked in step 109 whether the density p of the gas in the vehicle tank 31 has reached a predeterminable final value ρ _E. Since step 109 already ensures that ρ _T and ρ _m differ by a maximum of D, it is in principle irrelevant whether ρ _T or ρ _{m are used} for the comparison with the final value ρ _E. Of course, the mean or a weighted mean of ρ _T and ρ _m can also be used for the comparison with ρ _E. If the density p has reached the final value ρ _E , the filling is ended in step 110, otherwise the filling is continued.

An advantage of the described method is that the maximum permissible density or operating density ρ _E for a given gas is independent of the outside temperature at which the refueling takes place.

Another advantage, particularly in terms of security, is that the density of the gas in the vehicle tank in two different ways is determined.

In principle, it is possible that, for. B. one of the two sensors 32, 33, which are arranged in the vehicle tank, is faulty already at the beginning of the refueling. This then leads, among other things, to the fact that the initial mass m _{0 of} the gas is calculated incorrectly, and consequently the control variable ρ _m determined in the dispensing device is also incorrect. However, since the initial values p ₀ for the pressure and T ₀ for the temperature in the vehicle tank 31 recorded by means of the sensors 32, 33 are used only as an initial condition in the respective determination of the control variable ρ _m , the values for the density ρ _T determined in the tank become on the one hand and the values for the control variable ρ _m diverge more and more as the filling progresses, so that such errors are also recognized before the vehicle tank 31 is dangerously overfilled.

It goes without saying that the respective calculation of the density ρ _T does not have to be carried out in the motor vehicle. It is also possible that the electronics module 34 contains the measured values or data of the temperature sensor 33 and the pressure sensor 32, that is to say, for. B. p ₀ , T ₀ , p _T , T _T , transmitted to the dispensing device 2 and the determination of ρ ₀ and ρ _{T then} takes place there.

Claims (10)

Method for filling a vehicle tank with a gas, in which the vehicle tank (31) is connected to a delivery device (2) by means of a pressure-resistant line (10) and the pressurized gas from the storage unit (3) by means of the delivery device (2) the vehicle tank (31) is filled, characterized by the following steps: with the help of a sensor device (32, 33) which is arranged in the vehicle tank (31), the current value of a parameter (ρ _T ) is determined during the filling, which is representative of the current level of the vehicle tank (31), filling is ended when the parameter (ρ _T ) has reached a definable final value (ρ _E ). Method according to Claim 1, in which the final value (ρ _E ) of the parameter is independent of the temperature. Method according to Claim 1 or 2, in which the parameter is first determined before the vehicle tank (31) is filled with gas, so that the current fill level of the vehicle tank before the start of filling is known as the initial value (ρ ₀ ). Method according to one of the preceding claims, wherein in the dispensing device (2) the mass (m _G ) of the discharged gas is measured, from which a control variable (ρ _m ) corresponding to the parameter (ρ _T ) is determined, the control variable (ρ _m ) is compared with the parameter (ρ _T ) and an error message or filling is canceled if the deviation between the parameter (ρ _T ) and the control parameter (ρ _m ) exceeds a predefinable limit value (D). Method according to one of the preceding claims, in which the density (ρ _T ) of the gas in the vehicle tank (31) is determined as the parameter. Method according to one of the preceding claims, in which the sensor device arranged in the vehicle tank (31) comprises a temperature sensor (33) and a pressure sensor (31) with which the temperature and the pressure of the gas in the tank is measured, and from this the density (ρ _T ) of the gas is determined as a parameter. The method of claim 5 or 6, wherein: the density (ρ ₀ ) is first determined before the vehicle tank (31) is filled with gas, so that the current density of the gas in the vehicle tank before the start of filling is known as the initial value, the volume (V) of the vehicle tank (31) to be filled is transmitted to the dispensing device (2), from the volume (V) and the initial value of the density (ρ ₀ ) the initial mass (m ₀ ) of the gas, which is present in the vehicle tank before the start of filling, is determined. A method according to claim 7, in which in the dispensing device (2) using the volume (V) of the vehicle tank (31), the initial mass (m ₀ ) of the gas in the vehicle tank and the metrologically recorded mass (m _G ) of the released gas a comparison value determined for the density of the gas in the vehicle tank as a control variable (ρ _m ) and in each case compared with the density (ρ _T ) determined in the vehicle tank (31). Method according to Claim 8, in which the filling is terminated when the density reaches a predeterminable final value (ρ _E ), or when the deviation between the control variable (ρ _m ) and the density (ρ _T ) determined in the vehicle tank has a predefinable limit value (D ) exceeds. Gas refueling system operated according to a process according to a of the preceding claims.

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