DE102021204309A1 - Leak testing and component testing of a tank system - Google Patents

Abstract

The invention relates to a method for checking a tank system (1) for leaks, with a tank having a first chamber (3) with a first pressure sensor (7) and a second chamber (5) with a second pressure sensor (9), and the chambers (3, 5) are connected through a transfer valve (11) and through a pump connection (13), and the tank is connected to an external valve (17), with:- pumping over (S1) fuel from the first (3) to the second chamber ( 5) with closed external valve (17) and passage valve (11) by a pump (15), so that a negative pressure builds up in the first chamber (3) and an overpressure in the second chamber (5), - opening (S3) of the passage valve (11) and checking whether the pressure difference decreases, - checking (S4) whether the pressure in the first chamber (3) and the pressure in the second chamber (5) completely equalize over long periods of time.

Description

The invention relates to a method for leak testing and component testing of a tank system with a tank for holding liquid fuel, such a tank system with a control unit for leak testing and component testing of the tank system, and a vehicle with such a tank system.

Vehicle internal combustion engines typically run on liquid fuel such as gasoline. The liquid fuel is carried in a tank and fed to the internal combustion engine in a petrol line. For environmental and safety reasons, it is important that both the tank and the components between the tank and the combustion engine are tight, i. H. not only keep the liquid fuel, but also not release fuel vapors such as gasoline vapors into the environment of the vehicle. Canisters are therefore known in the prior art, in particular activated carbon canisters, which are typically arranged between the tank and the internal combustion engine and are designed to absorb fuel vapors which, in certain situations, can in turn be supplied to the internal combustion engine as fuel, in particular in gaseous form.

the U.S. 2014 0107906 A1 describes such a canister in a tank system. Furthermore, a two-part tank is described with a first and a second chamber, both of which can be closed in a pressure-tight manner, wherein liquid fuel can be pumped between the chambers by means of a pump for leak testing, in order to artificially increase the pressure in one chamber and in the other chamber counteracting the pressure to decrease. However, this does not check the function of the components used for this.

It is therefore an object of the invention to improve leak testing of a tank system, in particular for a vehicle, and also to test the components used for this.

The invention results from the features of the independent claims. Advantageous developments and refinements are the subject matter of the dependent claims.

• - Umpumpen von Treibstoff von der ersten Kammer in die zweite Kammer mit geschlossenem Außenventil und geschlossenem Durchlassventil, sodass sich in der ersten Kammer ein Unterdruck und in der zweiten Kammer ein Überdruck aufbaut,
• - Stoppen des Umpumpens, wenn eine vorgegebene Druckdifferenz zwischen den Kammern oder ein vorgegebener Absolutdruck in einer der Kammern gemäß dem ersten Drucksensor und/oder dem zweiten Drucksensor erreicht ist, und Geschlossenhalten des Außenventils und des Durchlassventils für eine vorgegebene Zeitdauer, und Prüfen, ob die Druckdifferenz zwischen den Kammern oder ein Absolutdruck über die vorgegebene Zeitdauer konstant bleibt,
• - Öffnen des Durchlassventils nach Ablauf der vorgegebenen Zeitdauer und Prüfen, ob sich die Druckdifferenz zwischen den Kammern abbaut,
• - Prüfen gemäß einem mit dem ersten Drucksensor erfassten Druck und/oder einem mit dem zweiten Drucksensor erfassten Druck, ob sich der Druck in der ersten Kammer und der Druck in der zweiten Kammer auf lange Zeiten vollständig angleichen.

A first aspect of the invention relates to a method for leak testing and component testing of a tank system with a tank for holding liquid fuel, the tank having a first chamber with a first pressure sensor and a second chamber with a second pressure sensor and the chambers through a passage valve and through a pump connection, a pump at the pump connection serving to pump liquid fuel between the chambers, at least one of the chambers being connected to an outlet with an external valve for withdrawing and/or filling liquid fuel into the tank, comprising the steps of:

• - Pumping fuel from the first chamber into the second chamber with the external valve and the passage valve closed, so that a negative pressure builds up in the first chamber and an overpressure in the second chamber,
• - Stopping pumping over when a predetermined pressure difference between the chambers or a predetermined absolute pressure in one of the chambers according to the first pressure sensor and/or the second pressure sensor is reached, and keeping the outer valve and the passage valve closed for a predetermined period of time, and checking whether the Pressure difference between the chambers or an absolute pressure remains constant over the specified period of time,
• - Opening the passage valve after the specified time has elapsed and checking whether the pressure difference between the chambers decreases,
• - checking according to a pressure detected with the first pressure sensor and/or a pressure detected with the second pressure sensor, whether the pressure in the first chamber and the pressure in the second chamber completely equalize for long periods of time.

The first chamber and the second chamber are thus in principle connected to one another by two channels: on the one hand, the pump connection, which can be considered fluid-tight when the pump is at a standstill, and on the other hand, through the passage valve, which is designed in particular as a lockable hose or pipe connection. Both the pump and the passage valve can preferably be activated or opened or closed by the activation of a control unit.

The liquid propellant can be moved between the first chamber and the second chamber through these channels. The liquid fuel is preferably gasoline or another hydrocarbon-based fuel.

The fuel is pumped from the first chamber into the second chamber by means of the pump, which is preferably controlled accordingly by the control unit. The pump can be the system pump, which during normal operation, outside of the diagnostic mode, the fuel pressure to the internal combustion engine. This means that no separate diagnostic pump is required. The pump can be a piston-cylinder based pump or a turbo pump, or a vane pump, or any other pump. Before this pumping over occurs, there is advantageously such a level of liquid fuel in the first chamber and in the second chamber that there is sufficient volume of air in the second chamber to be compressed so that fuel is pumped from the first chamber to the second chamber can be.

Further components of the tank system can also be arranged between the outer valve and the respective chamber. For example, the canister mentioned in the introduction for absorbing fuel vapors, corresponding lines in between, or the like. Accordingly, the tightness of the tank system can be checked up to the external valve.

The first pressure sensor and the second pressure sensor are advantageously always above a level of a respective chamber, so that they are never immersed in the liquid fuel. This advantageously facilitates the pressure measurement, since no hydrostatic pressure acts on a respective pressure sensor due to the liquid fuel.

The components tested during the component test serve in particular to carry out the leak test of the tank system. By checking whether the pressure difference between the chambers decreases after the passage valve has opened, it can be checked whether the passage valve has opened correctly. By checking whether the pressure in the first chamber and the pressure in the second chamber completely equalize over a long period of time, it is possible to check whether, firstly, the flow control valve has opened correctly and, secondly, whether the pressure sensors are working correctly, since they are sufficiently fast Pressure reduction can be assumed to be a correct functioning of the gate valve, but if the pressures do not equalize in the long term, defective pressure sensors can be assumed, since a constant stationary offset occurs where it should not occur with a correctly opened gate valve.

It is therefore an advantageous effect of the invention that not only is a leak test of the tank system carried out, but also the components used for the leak test are also tested. Such cases are therefore included in which a leak is detected by a test procedure, but while the tank is not leak-proof and the incorrect result was determined by defective components. Furthermore, the case can arise that the tank with both chambers and the surrounding components is actually tight, but the components for testing are defective and must be replaced. Both cases are covered by the method according to the invention, so that a leak test and a component test for the leak test of the tank system are carried out.

According to an advantageous embodiment, before fuel is pumped from the first chamber into the second chamber, the passage valve is opened without the pump being active, so that the same level of fuel and the same pressure distribution over the first chamber and in the second chamber Height of the chambers prevails, wherein the pressure detected by the first pressure sensor and the second pressure sensor is compared in each case and if there is a deviation, a fault in the passage valve or in the first and/or second pressure sensor is detected. According to this embodiment, before pumping over, the two chambers are in communication with one another and are in equilibrium with one another when the passage valve is correctly open. If a deviating result is recorded due to a deviation between the measurement of the first pressure sensor and the measurement of the second pressure sensor, it can be concluded that either the through-flow valve is incorrectly still closed or one of the pressure sensors is delivering incorrect results.

According to a further advantageous embodiment, when checking whether the pressure difference between the chambers or an absolute pressure remains constant over the specified period of time after pumping over, a pressure increase during the specified period of time in the first chamber and a pressure drop during the specified period of time in the second chamber compared to a respective limit value and the respective pressure is regarded as constant if the respective limit value is not exceeded.

According to a further advantageous embodiment, a leak in one of the chambers is determined when the limit value for one of the chambers is undershot and the other chamber exceeds the limit value, and a defect in the passage valve is determined if the limit values for both chambers are exceeded at the same time. According to this embodiment, the origin of a defect can advantageously be determined, since in the first case, when one limit value is complied with but not complied with for the other chamber, the chamber with the non-complied limit value is obviously defective. If both limit values are exceeded at the same time, it can be assumed that the flow control valve is defective.

According to a further advantageous embodiment, a pressure difference is determined at the first pressure sensor with regard to the points in time before and after pumping over, and from this a theoretical pressure difference is determined at the second pressure sensor with regard to the same points in time and compared with the actual pressure difference determined by the second pressure sensor with regard to the same points in time.

According to a further advantageous embodiment, a pressure difference is determined at the second pressure sensor with regard to the points in time before and after pumping over, and from this a theoretical pressure difference is determined at the first pressure sensor with regard to the same points in time and compared with the actual pressure difference determined by the first pressure sensor with regard to the same points in time.

The theoretical determination in the two aforementioned embodiments for a pressure sensor based on the measurements of the other pressure sensor in each case is preferably carried out using a thermodynamic model for the pressure increase through volume reduction. In particular, these models assume that the liquid fuel is incompressible, while the remaining air in the respective chamber is compressible. According to these specific embodiments, a defect in at least one of the pressure sensors can be inferred.

According to a further advantageous embodiment, when the passage valve opens after the specified period of time has elapsed, a check is made based on a pressure detected at the first pressure sensor and/or a pressure detected at the second pressure sensor as to whether the pressure difference between the chambers is decreasing sufficiently quickly. For this purpose, empirical or theoretically determined values are stored in particular in a control unit, which are compared with the pressure profile over time in the chambers. The pressure reduction takes place in particular in a non-linear manner, that is to say faster with higher pressure differences than with lower pressure differences, so that the initial pressure difference is taken into account when checking the speed of the reduction in the pressure difference. If the reduction in pressure difference does not take place as quickly as expected when the passage valve is supposed to be open, then it can be concluded that the passage valve is defective and is not fully open, for example.

According to a further advantageous embodiment, an open passage valve and/or a defective pump is detected if, after pumping has stopped, the pressure detected by the first pressure sensor and the pressure detected by the second pressure sensor are the same.

According to a further advantageous embodiment, the method steps are repeated several times.

• - Öffnen des Durchlassventils und des Außenventils und Prüfen, ob der vom ersten Drucksensor erfasste Druck gleich der vom zweiten Drucksensor erfasste Druck ist, und Erkennen eines Fehlers im ersten Drucksensor und/oder zweiten Drucksensor, wenn eine Abweichung vorliegt.

According to a further advantageous embodiment, the method also has the step:

• - opening the passage valve and the outer valve and checking whether the pressure detected by the first pressure sensor is equal to the pressure detected by the second pressure sensor, and detecting a fault in the first pressure sensor and/or the second pressure sensor if there is a deviation.

According to a further advantageous embodiment, it is checked whether the pressure detected by the first pressure sensor is equal to the pressure detected by the second pressure sensor and is equal to the atmospheric pressure of the area surrounding the tank system.

Another aspect of the invention relates to a tank system with a tank and a control unit for leak testing and component testing of the tank system, the tank being used to hold liquid fuel and having a first chamber with a first pressure sensor and a second chamber with a second pressure sensor and the chambers connected through a transfer valve and through a pump connection, a pump of the pump connection serving to pump liquid fuel between the chambers, at least one of the chambers being connected to an outlet with an external valve for withdrawing and/or filling liquid fuel into the tank, wherein the control unit is designed to control the pump for pumping fuel from the first chamber into the second chamber with the external valve closed and the passage valve closed, so that a negative pressure builds up in the first chamber and an overpressure builds up in the second chamber, stopping the pumping, when a predetermined pressure difference between the chambers or a predetermined absolute pressure in one of the chambers according to the first pressure sensor and/or the second pressure sensor is reached, and wherein the control unit is also designed to keep the outer valve and the passage valve closed for a predetermined period of time and for testing, whether the pressure difference between the chambers or an absolute pressure remains constant over the predetermined period of time, and for opening the gate valve after the predetermined period of time has elapsed and for checking whether the pressure difference between the chambers is decreasing, and for checking according to a pressure detected by the first pressure sensor and/or one with the second pressure sensor detected pressure, whether the pressure in the first chamber and the pressure in the second chamber fully equalize for long periods of time.

Advantages and preferred developments of the proposed tank system result from an analogous and analogous transfer of the statements made above in connection with the proposed method.

A further aspect of the invention relates to a vehicle with a tank system as described above and below.

Further advantages, features and details result from the following description, in which at least one exemplary embodiment is described in detail-if necessary with reference to the drawing. Identical, similar and/or functionally identical parts are provided with the same reference symbols.

• 1: Ein Tanksystem gemäß einem Ausführungsbeispiel der Erfindung.
• 2: Ein Verfahren zur Dichtheitsprüfung und Komponentenprüfung des Tanksystems aus der 1.

Show it:

• 1 : A tank system according to an embodiment of the invention.
• 2 : A method for leak testing and component testing of the tank system from the 1 .

The representations in the figures are schematic and not to scale.

1 1 shows a tank system 1 with a tank, the tank serving to hold liquid fuel and having a first chamber 3 with a first pressure sensor 7 and a second chamber 5 with a second pressure sensor 9 . Each chamber of the tank is one-third filled with liquid fuel such as gasoline. The chambers 3 , 5 are connected in principle by a passage valve 11 and by a pump connection 13 .

A turbo pump 15 of the pump connection 13 is ready to circulate the liquid fuel between the chambers 3.5. At the first chamber 3, an outlet is arranged, which has a closable external valve 17 outside of the chambers 3.5.

Liquid propellant can be removed from or added to the tank through the outlet. The outlet shown is also representative of separate outlets, one for removing fuel from the tank for delivery to an internal combustion engine and an outlet for adding fuel to the tank.

• - Umpumpen S1 von Treibstoff von der ersten Kammer 3 in die zweite Kammer 5 mit geschlossenem Außenventil 17 und geschlossenem Durchlassventil 11, sodass sich in der ersten Kammer 3 ein Unterdruck und in der zweiten Kammer 5 ein Überdruck aufbaut,
• - Stoppen S2 des Umpumpens, wenn eine vorgegebene Druckdifferenz zwischen den Kammern 3,5 oder ein vorgegebener Absolutdruck in einer der Kammern 3,5 gemäß dem ersten Drucksensor 7 und/oder dem zweiten Drucksensor 9 erreicht ist, und Geschlossenhalten des Außenventils 17 und des Durchlassventils 11 für eine vorgegebene Zeitdauer, und Prüfen, ob die Druckdifferenz zwischen den Kammern 3,5 oder ein Absolutdruck über die vorgegebene Zeitdauer konstant bleibt,
• - Öffnen S3 des Durchlassventils 11 nach Ablauf der vorgegebenen Zeitdauer und Prüfen, ob sich die Druckdifferenz zwischen den Kammern 3,5 abbaut,
• - Prüfen S4 gemäß einem mit dem ersten Drucksensor 7 erfassten Druck und/oder einem mit dem zweiten Drucksensor 9 erfassten Druck, ob sich der Druck in der ersten Kammer 3 und der Druck in der zweiten Kammer 5 auf lange Zeiten vollständig angleichen.
• - Öffnen S5 des Durchlassventils 11 und des Außenventils 17 und Prüfen, ob der vom ersten Drucksensor 7 erfasste Druck gleich der vom zweiten Drucksensor 9 erfasste Druck ist, und Erkennen eines Fehlers im ersten Drucksensor 7 und/oder zweiten Drucksensor 9, wenn eine Abweichung vorliegt.

2 shows a method for leak testing and component testing of the tank system 1 1 . The tank system 1 also has a control unit (not shown) for leak testing and component testing of the tank system 1 . The following steps are carried out with the control unit, which lead to different states of the tank system 1, which are shown in FIG 2 shown in the two partial images:

• - Pumping S1 of fuel from the first chamber 3 into the second chamber 5 with the external valve 17 and the passage valve 11 closed, so that a negative pressure builds up in the first chamber 3 and a positive pressure builds up in the second chamber 5,
• - Stopping S2 of pumping over when a predetermined pressure difference between the chambers 3.5 or a predetermined absolute pressure in one of the chambers 3.5 according to the first pressure sensor 7 and/or the second pressure sensor 9 is reached, and keeping the outer valve 17 and the passage valve closed 11 for a specified period of time, and checking whether the pressure difference between the chambers 3.5 or an absolute pressure remains constant over the specified period of time,
• - Opening S3 of the passage valve 11 after the specified period of time has elapsed and checking whether the pressure difference between the chambers 3.5 decreases,
• - Check S4 according to a pressure detected with the first pressure sensor 7 and/or a pressure detected with the second pressure sensor 9 whether the pressure in the first chamber 3 and the pressure in the second chamber 5 completely equalize for long periods of time.
• - Opening S5 of the passage valve 11 and the outer valve 17 and checking whether the pressure detected by the first pressure sensor 7 is equal to the pressure detected by the second pressure sensor 9, and detecting a fault in the first pressure sensor 7 and/or second pressure sensor 9 if there is a deviation .

Although the invention has been illustrated and explained in more detail by means of preferred exemplary embodiments, the invention is not restricted by the disclosed examples and other variations can be derived therefrom by a person skilled in the art without departing from the protective scope of the invention. It is therefore clear that a large number of possible variations exist. It is also understood that the exemplary embodiments given are really only examples and should not be construed as limiting in any way the scope, applications or configuration of the invention. Rather, the preceding description and the description of the figures enable the person skilled in the art to concretely implement the exemplary embodiments zen, whereby the person skilled in the art, knowing the inventive concept disclosed, can make a variety of changes, for example with regard to the function or the arrangement of individual elements mentioned in an exemplary embodiment, without leaving the scope of protection, which is defined by the claims and their legal equivalents, such as further-reaching Explanations in the description, is defined.

reference list

1

tank system

3

first chamber

5

second chamber

7

first pressure sensor

9

second pressure sensor

11

passage valve

13

pump connection

15

pump

17

outside valve

S1

pump over

S2

To stop

S3

Open

S4

Check

S5

Open

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was 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.

Patent Literature Cited

• US20140107906A1 [0003]

Claims (13)

Method for leak testing and component testing of a tank system (1) with a tank for holding liquid fuel, the tank having a first chamber (3) with a first pressure sensor (7) and a second chamber (5) with a second pressure sensor (9). and the chambers (3,5) are connected through a transfer valve (11) and through a pump connection (13), a pump (15) at the pump connection (13) serving to pump liquid fuel between the chambers (3,5). , wherein at least one of the chambers (3.5) is connected to an outlet with an external valve (17) in order to remove and/or fill in liquid fuel from the tank, comprising the steps: - Pumping (S1) of fuel from the first chamber (3) into the second chamber (5) with the external valve (17) and the passage valve (11) closed, so that there is a negative pressure in the first chamber (3) and in the second chamber (5) an overpressure builds up, - Stopping (S2) the pumping over when a predetermined pressure difference between the chambers (3,5) or a predetermined absolute pressure in one of the chambers (3,5) according to the first pressure sensor (7) and/or the second pressure sensor (9) is reached and keeping the outer valve (17) and the passage valve (11) closed for a predetermined period of time, and checking whether the pressure difference between the chambers (3.5) or an absolute pressure remains constant over the predetermined period of time, - Opening (S3) of the passage valve (11) after the specified period of time has elapsed and checking whether the pressure difference between the chambers (3.5) decreases, - checking (S4) according to a pressure detected by the first pressure sensor (7) and/or a pressure detected by the second pressure sensor (9) whether the pressure in the first chamber (3) and the pressure in the second chamber (5 ) fully adjust for long periods. procedure after claim 1 , wherein before fuel is pumped from the first chamber (3) into the second chamber (5), the passage valve (11) is open without the pump (15) being active, so that in the first chamber (3) and in the second chamber (5), the same level of fuel and the same pressure distribution over the height of the chambers (3,5) prevails, the pressure detected by the first pressure sensor (7) and the pressure detected by the second pressure sensor (9) being compared and at one Deviation, a fault in the passage valve (11) or in the first and/or second pressure sensor (9) is detected. Method according to one of the preceding claims, wherein when checking whether the pressure difference between the chambers (3,5) or an absolute pressure remains constant over the predetermined period of time after pumping over, a pressure increase during the predetermined period of time in the first chamber (3) and a pressure drop during the predetermined period of time in the second chamber (5) is compared with a respective limit value and the respective pressure is regarded as constant if the respective limit value is not exceeded. procedure after claim 3 , wherein when falling below the limit value for one of the chambers (3.5) and when exceeding the limit value for the other of the chambers (3.5), a leak in one of the chambers (3.5) is detected and at the same time exceeding the limit values for both chambers (3.5) a defect in the passage valve (11) is detected. Method according to one of the preceding claims, wherein a pressure difference at the first pressure sensor (7) with regard to the points in time before and after pumping is determined and from this a theoretical pressure difference at the second pressure sensor (9) with regard to the same points in time is determined and with that of the second pressure sensor (9) determined actual pressure difference is compared with respect to the same points in time. Method according to one of the preceding claims, wherein a pressure difference at the second pressure sensor (9) with regard to the points in time before and after pumping is determined and from this a theoretical pressure difference at the first pressure sensor (7) with regard to the same points in time is determined and with that of the first pressure sensor (7) determined actual pressure difference is compared with respect to the same points in time. Method according to one of the preceding claims, wherein when the passage valve (11) opens after the predetermined period of time has elapsed, depending on a pressure detected at the first pressure sensor (7) and/or a pressure detected at the second pressure sensor (9), it is checked whether the Pressure difference between the chambers (3.5) degrades sufficiently quickly. Method according to one of the preceding claims, wherein an open passage valve (11) and/or a defective pump (15) is detected if, after pumping has stopped, the pressure detected by the first pressure sensor (7) and the pressure detected by the second pressure sensor (9). pressure are the same. Method according to one of the preceding claims, wherein the method steps are repeated several times. Method according to one of the preceding claims, further comprising the step of: - opening (S5) the passage valve (11) and the outer valve (17) and checking whether the pressure detected by the first pressure sensor (7) is the same as that detected by the second pressure sensor (9). Pressure is, and detecting a fault in the first pressure sensor (7) and / or second pressure sensor (9) when there is a deviation. procedure after claim 10 , it being checked whether the pressure detected by the first pressure sensor (7) is equal to the pressure detected by the second pressure sensor (9) and is equal to the atmospheric pressure around the tank system (1). Tank system (1) with a tank and a control unit for leak testing and component testing of the tank system (1), the tank serving to hold liquid fuel and a first chamber (3) with a first pressure sensor (7) and a second chamber (5) having a second pressure sensor (9) and the chambers (3,5) are connected by a flow valve (11) and by a pump connection (13), a pump (15) of the pump connection (13) serving to pump liquid fuel between the chambers (3,5), at least one of the chambers (3,5) being connected to an outlet with an external valve (17) in order to remove and/or fill in liquid fuel from the tank, the control unit being designed to operate the pump ( 15) to pump fuel from the first chamber (3) into the second chamber (5) with the external valve (17) and the passage valve (11) closed, so that there is a negative pressure in the first chamber (3) and in the second chamber ( 5) an overpressure builds up to stop pumping when a predetermined pressure difference between the chambers (3.5) or a predetermined absolute pressure in one of the chambers (3.5) according to the first pressure sensor (7) and/or the second pressure sensor ( 9) is reached, and wherein the control unit is also designed to keep the outer valve (17) and the passage valve (11) closed for a predetermined period of time and to check whether the pressure difference between the chambers (3,5) or an absolute pressure is above the predetermined period remains constant, and to open the passage valve (11) after the specified period of time has elapsed and to check whether the pressure difference between the chambers (3.5) is decreasing, and to check according to a pressure detected by the first pressure sensor (7) and /or a pressure detected by the second pressure sensor (9), whether the pressure in the first chamber (3) and the pressure in the second chamber (5) completely equalize over a long period of time. Vehicle with a tank system (1). claim 12 .

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