DE102013011858A1 - Method for indicating fuel content of compressed gas storage for gaseous fuel in vehicle, involves setting level of fuel in tank after refueling reaches predetermined pressure threshold and displaying level of fuel in tank - Google Patents

Abstract

The method involves computing the present gas mass in the compressed gas reservoir (3) based on pressure (p) and temperature, setting the level of fuel in the tank after refueling reaches predetermined pressure threshold (pS) and displaying the level of fuel in the tank. The start value for the mass of gas than 100% of tank capacity is computed as a function of temperature and maximum pressure when the pressure detected during filling is maximum or above the pressure threshold.

Description

The invention relates to a method for displaying the tank contents in a compressed gas storage device for gaseous fuels in a vehicle according to the preamble of claim 1.

Vehicles having compressed gas storage for gaseous fuels, for example compressed natural gas or hydrogen, are known from the general state of the art. The vehicles can be driven with the fuel, for example, directly via an internal combustion engine or indirectly, in which the fuel is converted, for example in a fuel cell into electrical energy, which can then be used for electrically driving the vehicle.

A problem with vehicles with compressed gas storage for gaseous fuels is that the display of the tank contents is correspondingly difficult and is typically based on the indirect calculation of a mass. For this purpose, the tank pressure and the temperature are taken into account, so that from the calculated mass, a residual amount of fuel can be displayed as the tank contents of the compressed gas storage in the vehicle. The state of the art in this context is on the DE 11 2008 002 826 T5 directed.

Although this calculation of the mass allows a comparatively accurate display and can thus help to calculate a residual range for the vehicle comparatively accurate. However, the problem here is that gas filling stations for refueling the compressed gas storage provide the gas at different pressures. For example, in compressed natural gas is typically assumed from a nominal pressure of 240 bar. However, some petrol stations are unable to deliver more than 180 bar, for example at 20 ° C, due to the technology used in them. Other filling stations are in turn able to provide 200, 220 or even 240 bar at a gas temperature of 20 °. Still other gas stations work with higher pressures, for example 240 bar at 0 ° C, in order to bring more gas into the vehicle and to optimize the conversion. All this leads now on the one hand to different ranges, which is so completely realistic and must be accepted. On the other hand, depending on the gas station usually in the display of the tank contents then just not the indication that the vehicle was fully refueled, although this is within the capabilities of the gas station is quite. To counteract this problem and to indicate to the driver that his vehicle has been fully fueled, already today, a pressure threshold is set, from which the tank contents to 100%, that is, the display, which has been fully refueled set. To illustrate the typically occurring cases with rather poor gas stations, this threshold is set, for example at natural gas filling stations to an empirical value of about 160-180 bar at 240 bar nominal pressure. For hydrogen, which is stored with corresponding higher pressures of, for example, 700 bar nominal pressure, then comparable applies in the relevant pressure ranges.

The serious disadvantage of this approach is that the display of the tank contents by the driver of the vehicle is often perceived as very unrealistic, such as when refueling with 220 bar at 20 ° C and a predetermined pressure threshold at, for example, 170 bar at 20 ° C the display of the tank contents "hang" for a very long period of the journey at full and then fall off faster. This represents a significant disadvantage for the user of the vehicle.

The object of the present invention is now to improve a method for displaying the tank contents of a compressed gas storage, in particular with regard to the abovementioned disadvantages.

According to the invention, this object is achieved by the method having the features in the characterizing part of claim 1. Advantageous embodiments and developments of the device will become apparent from the dependent therefrom dependent claims.

Also in the method according to the invention, as in the prior art, it is such that, when a predetermined pressure threshold is exceeded, the tank contents are set to 100% and displayed accordingly. According to the invention, however, it is now provided that this 100% value of the tank contents and the display receives an individual value which defines a corresponding starting value for the gas mass, which is calculated as a function of the temperature and in particular of the maximum tank pressure. The maximum tank pressure can, as already explained above, vary depending on individual gas filling stations. In the method according to the invention, the starting value for the display of 100% tank content of this capacity of the gas filling station used is adjusted. The display 100% tank content corresponds then in the reality of the display 100% tank content, so with increasing decrease in gas mass and the value of the display decreases accordingly and just not stuck in a refueling with relatively high pressure over a long time at 100%.

According to an advantageous embodiment of the method according to the invention, it is therefore provided that the display of the tank contents is reduced in percentage from this starting value with decreasing gas mass. As a result, a very realistic display is achieved, which always indicates the percentage remainder of the tank contents as a function of the gas mass fueled according to the capacity of the gas station.

The maximum tank pressure can be corrected with a correction value or a correction factor. This is due to the device typically warming during refueling of decisive advantage, so that, for example, a maximum tank pressure, for example, at 95% of the measured maximum pressure can be set to correct corresponding heating effects.

The refueling can be detected automatically according to an advantageous embodiment of the method by a detected pressure gradient, which is above a predetermined value. An increase in pressure, which is correspondingly fast and / or exceeds a corresponding pressure threshold, for example a pressure difference of 80 bar in a very short time can be used as an indication that the vehicle has been fueled. All occurring during operation pressure increases, for example, by heating, when the vehicle is parked in the sun or the like, will in practice have a much lower pressure gradient and / or maximum value of the pressure increase, so that safe and reliable refueling be detected automatically by this method can.

In a very favorable and advantageous development of the method according to the invention, the maximum tank pressure can now also be divided and displayed according to its value into one of several classes. Thus, it is possible to indicate to the driver with what "quality" his vehicle has been fueled in the gas station. On the one hand, this can be used so that the driver gets a realistic estimate of the possible range and, on the other hand, can also be used so that the driver knows in which filling station he has more or less pressure available. In the worst case, too high a pressure in the filling station, which may be to increase the turnover in the interest of the gas station operator, namely, adversely affect the life of his system, because this is overloaded by the high tank pressure in the refueling.

Accordingly, in addition to the indication to the driver, it may also be provided that the maximum tank pressure or the class into which it has been classified is stored. From a certain tank pressure, for example, an error flag can be set, so that it can be determined during an inspection or maintenance that was often filled with too high pressure. Any leaks, which must be noticed during maintenance and must be remedied, can then be traced back to their cause, so that a comparatively simple and clear diagnosis is possible.

In a further very favorable embodiment of this idea, it can now also be provided that, together with the value of the maximum tank pressure and / or the class in which this was divided, the location data of refueling, z. In the form of GPS data. As a result, it would then be possible, for example, to identify gas stations, which constantly work with too low or too high pressure. In particular, filling stations which operate at too high pressure and thus could endanger the long-term safety of the systems can then be addressed, for example, by the vehicle manufacturers and asked to lower the pressure to a level which is more suitable for the vehicle systems.

In a further very favorable embodiment of the method according to the invention, it can now also be provided that in addition the gas quality is recorded and displayed. The quality of the refueled gas can be detected, in particular after a certain period of operation, for example of the internal combustion engine or the fuel cell, by evaluations of purity, calorific value or the like which take place in the vehicle electronics anyway. By this indication, whether it is high-quality or less high-quality gas, which is ideally also divided into classes, in particular together with an indication of the maximum tank pressure in one or more classes can be created a very simple display for the driver, this example in a traffic light display or the like, the complex conditions prepared accordingly to inform him with what pressure and what gas quality he has refueled his vehicle.

Further advantageous embodiments of the method according to the invention will become apparent from the remaining dependent subclaims and will be apparent from the embodiment, which is described below with reference to the figures.

Showing:

1 a vehicle indicated in principle, which is suitable for carrying out the method according to the invention during refueling; and

2 a not to scale graphical representation of the display of the tank contents according to the inventive method.

In the presentation of the 1 is a vehicle indicated in principle 1 to recognize which in the example shown here about an indicated internal combustion engine 2 to be driven as a drive system. Instead of the internal combustion engine 2 would be just as well the combination of a fuel cell system and an electric drive motor as a drive system conceivable. The drive system, whether with a fuel cell system or the combustion engine indicated here 2 , Is supplied with a gaseous fuel, such as natural gas or hydrogen, which in a compressed gas storage 3 in the vehicle 1 is stored. The compressed gas storage 3 For example, it may be in the form of one or more substantially bottle-shaped storage volumes. The refueling of the compressed gas storage 3 takes place in a petrol station via a refueling system indicated in principle 4 which in turn has a gas supply, not shown, and a compressor for refueling the vehicle 1 or its compressed gas storage 3 having. About a refueling line 5 is the refueling system 4 while refueling with a filler neck 6 of the vehicle 1 connected, which in turn via a fixed line connection 7 inside the vehicle 1 with the compressed gas storage 3 communicated. During refueling, the temperature and pressure of the refueled gas are detected. On the one hand, this can be done in the refueling area 4 take place and alternatively or additionally in the vehicle 1 what in the presentation of the 1 a temperature sensor 8th and a pressure sensor 9 in the area of a filler neck of the compressed gas storage 3 are indicated. About a corresponding communication between the vehicle 1 and the refueling system 4 for example, along the refueling line 5 or by wireless communication, the values can be exchanged and / or adjusted accordingly.

In the area of the vehicle 1 It is now so that the values of the sensors 8th . 9 to an electronics 10 be passed, which then in the embodiment of 1 a complex display instrument 11 controls. The most important part of this complex display instrument 11 is an ad 12 for the tank contents. In addition, the display instrument includes 11 two in this embodiment as traffic light displays 13 . 14 executed instruments which can indicate the quality of the refueling and the gas quality in a later described manner.

As already mentioned, it is now the case that, due to the settings of the system operator and / or the performance of their compressors, each refueling system provides a different pressure for refueling. For example, via the pressure sensor 9 can now at the corresponding via the temperature sensor 8th detected temperature of this occurring during refueling maximum pressure p, which through the refueling system 4 can be provided. Alternatively, it would also be conceivable, this in the field of refueling 4 and via wireless communication or over one in the field of refueling 5 attached communication path to the vehicle 1 or the electronics 10 tell. The configuration of the display 12 the tank contents is now carried out so that from a certain threshold p _{S of} this pressure p, for example, from a maximum pressure of 160 bar in the case of refueling with natural gas, the fuel gauge is set to full. In the diagram of 2 is a display value A at 100% and the value of 170 bar shown at the right end of the lower curve. Creates the refueling system 4 For example, a pressure of 200 bar, the dashed curve comes into play, at a pressure of 240 bar, for example, the upper solid curve. In principle, it is thus dependent on the fueling system 4 to be achieved maximum pressure p a different starting value in the compressed gas storage 4 stored gas mass ready, if the pressure threshold p _{S has been} exceeded. In 2 the representation is temperature-corrected, so that, for example, the normal temperature of 20 ° C is assumed in all situations or these are converted accordingly. Depending on the refueling system 4 and the maximum pressure p reached by it is now for the fuel gauge 12 set a different starting value for the display A full = 100%. Starting from this value, the display A moves with consumption of the gas from the compressed gas storage 3 along their respective in 2 recognizable - shown in three examples - curves down, so that always a realistic display is achieved starting from the actual gas-filled mass of gas.

Besides, it is now so that it is for the driver of the vehicle 1 Of course, it is of interest, which "quality" the refueling at the respective refueling system 4 has reached. Accordingly, can be via the traffic light display 13 and a classification of the maximum pressure value p achieved, for example, such that values below 200 bar are shown as rather poor and values above 200 bar as normal, achieve a corresponding indication of refueling, so that the driver see if he is using appropriately "normal" or low pressure from the refueling system 4 been supplied with gas. For example, another class may be located at 240 bar or above, so that the driver can see that this station has fueled with much or too much pressure, which in the long term the safety of the compressed gas storage 3 if it is very often fueled at this gas station could endanger. In this case, an error value may also be generated and stored in a fault memory 15 be stored in the vehicle. This optional fault memory 15 also has a system for determining location data, such as a GPS system 16 , so that not only the occurrence of a refueling with excessive pressure is documented in case of failure, but also the place of refueling. This can then be traced back to the respective gas station, so that if necessary, the operator can be addressed that he should reduce the available pressure.

Another possibility is the use of a quality sensor 17 for the quality of the gas used. This is so far known from the prior art and is already used today to determine the quality of the gas as soon as a certain amount of gas has been burned or reacted. In the embodiment shown here, this optional quality sensor 17 also adds value to the electronics for the quality of the gas 10 report back, which then in the second traffic light display 14 can be displayed accordingly, with a classification of the gas quality in bad, normal and good or in even more classes certainly makes sense, because the driver typically can not do so much with a pure numerical value.

Overall, this creates a very complex advertising instrument 11 , which informs the driver after refueling very comprehensive, and which ensures that in particular the display 12 the tank contents safely and reliably works and gives realistic values, so with starting consumption of gas from the compressed gas storage 3 this consumption is also displayed, and the display is not stuck for a very long time at 100% due to a very high refueling pressure.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 112008002826 T5 [0003]

Claims (10)

Method for displaying the tank contents of a compressed gas storage tank ( 3 ) for gaseous fuel in a vehicle ( 1 ), wherein based on pressure (p) and temperature, the present gas mass in the compressed gas storage ( 3 ) is calculated, after a refueling from the attainment of a predetermined pressure threshold (p _S ), the tank content is set to 100% and displayed, characterized in that additionally the maximum at or above the pressure threshold (p _S ) lying pressure (p) during the refueling is detected, after which a starting value for the gas mass is calculated as 100% tank content as a function of temperature and maximum pressure (p). A method according to claim 1, characterized in that the display (A) of the tank contents is reduced in percentage from the starting value with decreasing gas mass. A method according to claim 1 or 2, characterized in that the maximum tank pressure (p) is corrected with a correction value or correction factor. A method according to claim 1, 2 or 3, characterized in that the refueling is detected automatically by a detected pressure gradient, which is above a predetermined value. Method according to one of claims 1 to 4, characterized in that the pressure threshold (p _S ) is set to a value between about 60-80% of the nominal pressure. Method according to one of claims 1 to 5, characterized in that the maximum tank pressure (p) is divided according to its value in one of several classes, after which the class is displayed. A method according to claim 6, characterized in that the classes comprise at least one of "low pressure", "normal pressure" and "high pressure" fueling. A method according to claim 6 or 7, characterized in that the maximum tank pressure (p) or the class into which it has been classified, in a permanent memory ( 15 ) is stored. A method according to claim 8, characterized in that stored together with the value or the class of the maximum tank pressure (p) the location data of refueling. Method according to one of claims 1 to 9, characterized in that in addition the quality of the gaseous fuel is detected and displayed.

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