Method for enabling refueling of a motor vehicle and motor vehicle

Abstract

A method grants an enablement of refueling of a motor vehicle. The method includes the steps: i) detecting a tank temperature value which is indicative of the present temperature of at least one pressure vessel of the motor vehicle and/or of the fuel stored in the at least one pressure vessel; ii) determining a temperature difference value which is indicative of the present difference between the tank temperature value and an ambient temperature value which is indicative of the ambient temperature; and iii) releasing a tank flap, wherein the tank flap is released by the motor vehicle for the purposes of refueling only if the temperature difference value is lower than a temperature difference threshold value.

Claims

1. A method for granting an enablement of refueling of a motor vehicle, the method comprising: detecting a tank temperature value which is indicative of a present temperature of at least one pressure vessel of the motor vehicle and/or of fuel stored in the at least one pressure vessel; determining a temperature difference value which is indicative of a present difference between the tank temperature value and an ambient temperature value which is indicative of ambient temperature; and releasing a tank flap, wherein the tank flap is released by the motor vehicle for the purposes of refueling, only if the temperature difference value is lower than a temperature difference threshold value.

2. The method according to claim 1, wherein the temperature difference threshold value varies with the ambient temperature.

3. The method according to claim 1, wherein a prevention of a follow-up refueling process is activated only if the tank flap has been closed and the vehicle is driven.

4. The method according to claim 1, wherein the temperature difference threshold value is selected such that, during a refueling process, taking into consideration the ambient temperature value, a maximum admissible tank temperature value is not reached.

5. The method according to claim 1, wherein the temperature difference threshold value is indicative of a maximum temperature difference of at most 20° C.

6. The method according to claim 1, further comprising the step of: outputting a notification if the temperature difference value is not lower than the temperature difference threshold value.

7. The method according to claim 6, further comprising the step of: outputting a notification if the temperature difference value again becomes lower than the temperature difference threshold value.

8. The method according to claim 1, wherein after a refueling process has taken place, readiness of the motor vehicle for driving is granted only if the tank flap has been transferred back into a non-released state after the refueling process.

9. The method according to claim 1, further comprising the step of: determining whether a predicted temperature difference value will be lower than the temperature difference threshold value if a filling station in a surroundings of the vehicle is traveled to.

10. A method for refueling a motor vehicle, the method comprising: releasing a tank flap as a result of granting of an enablement of refueling by: detecting a tank temperature value which is indicative of a present temperature of at least one pressure vessel of the motor vehicle and/or of fuel stored in the at least one pressure vessel; determining a temperature difference value which is indicative of a present difference between the tank temperature value and an ambient temperature value which is indicative of ambient temperature, wherein the tank flap is released by the motor vehicle purposes of refueling, only if the temperature difference value is lower than a temperature difference threshold value; and refueling the motor vehicle taking into consideration the ambient temperature value.

11. A motor vehicle having a pressure vessel system, comprising: at least one pressure vessel; at least one tank flap; and at least one control unit, wherein the control unit is configured to: detect a tank temperature value which is indicative of a present temperature of the at least one pressure vessel and/or of fuel stored in the at least one pressure vessel, determine a temperature difference value which is indicative of a present difference between the temperature value and an ambient temperature value which is indicative of ambient temperature, and release the tank flap by the motor vehicle for purposes of refueling only if the temperature difference value is lower than a temperature difference threshold value.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic flow diagram of the technology disclosed herein.

(2) FIG. 2 schematically shows the warming of the pressure vessel in a manner dependent on the pressure vessel internal pressure.

(3) FIG. 3 schematically shows the profile with respect to time of the fuel temperature T.sub.F during the refueling process at one fueling pump.

(4) FIG. 4 schematically shows the profile with respect to time of the fuel temperature T.sub.F during the refueling process at two fueling pumps.

DETAILED DESCRIPTION OF THE DRAWINGS

(5) The method disclosed here begins with the step S100 in FIG. 1. In the step S200, it is checked whether a demand for refueling is present. A demand for refueling may be signaled by the driver of the motor vehicle for example by actuation of a refueling switch. Such a demand for refueling could however also be signaled in some other way. If the control unit detects no demand for refueling in the step S200, then the method is recommenced with step S100. However, if a demand for refueling is present, then it is determined in the step S300 whether the present temperature difference value TD.sub.actual is lower than the temperature difference threshold value TD.sub.threshold. If this is the case, then the tank flap is released in the step S400. It is thus possible for the tank flap to be opened and for the refueling of the pressure vessel system to be performed. However, if the present temperature difference value TD.sub.actual is not lower than the temperature difference threshold value TD.sub.threshold, then the tank flap is not released. It is preferably then possible for a corresponding notification to be output to the driver. The driver can then drive the at least partially refueled motor vehicle, whereby the temperature of the fuel and/or of the pressure vessel decreases.

(6) In FIG. 2, the temperature in the pressure vessel is plotted versus the pressure vessel internal pressure. Here, a solid line is used to show a first refueling process which begins at a starting tank pressure p.sub.a0 and a starting temperature T.sub.a0 and, in this case, is ended when the refueling end pressure p.sub.e has been reached. As a result of this first complete refueling process without termination of refueling the fuel warms to the temperature T.sub.a1.

(7) If it is now assumed that said first refueling process is terminated in the presence of a refueling termination pressure p.sub.b1, then the fuel in the pressure vessel has warmed to the temperature T.sub.b1 as a result of this partial refueling process. If the refueling process is now continued, then the pressure vessel has generally not cooled completely. In the example shown here, the driver seeks to initiate a second refueling process at a point in time at which the pressure vessel exhibits a pressure vessel internal pressure p.sub.b2 and the fuel exhibits a fuel temperature T.sub.b2. If the pressure vessel were now refueled up to the refueling end pressure p.sub.e, a temperature T.sub.b3 considerably higher than the maximum admissible tank temperature T.sub.G would arise in the interior of the pressure vessel. Such a refueling process would lead to inadmissible overheating of the pressure vessel.

(8) FIG. 3 schematically shows the profile with respect to time of the fuel temperature during the first complete refueling process without refueling termination at one fueling pump (for example the solid line in FIG. 2). At the start of the refueling process, the fuel flows at a temperature T.sub.Fw into the pressure vessel, which temperature is considerably higher than the temperature T.sub.Fc of the fuel provided by the filling station. This is because the feed lines in the filling station and in the vehicle to the at least one pressure vessel are generally not cooled. Thus, the fuel which is controlled to a temperature T.sub.Fc in the filling station is at least partially warmed on the path to the pressure vessel. Said feed lines gradually cool during the refueling process. The temperature T.sub.F of the inflowing fuel thus gradually decreases until the temperature T.sub.F substantially corresponds to the temperature T.sub.Fc of the fuel of the filling station. Here, at the time t.sub.a1, the first refueling process is completed as soon as the refueling end pressure p.sub.e has been reached. As a result of the warmed feed lines, an additional amount of heat is introduced into the pressure vessel, which is represented in FIG. 3 by the hatched area.

(9) FIG. 4 schematically shows the profile with respect to time of the fuel temperature T.sub.F during two successive refueling processes which take place at two different fueling pumps. The first refueling process at the first fueling pump again begins at the time t.sub.a0. Up until the time t.sub.a0′, the fuel is introduced at a temperature T.sub.F which is higher than the temperature T.sub.Fc of the fuel controlled in terms of temperature in the filling station. An additional amount of heat is thus introduced in relation to the ideal cold refueling process, the additional amount of heat being illustrated here by the hatched area. At the time t.sub.b1, the refueling process is interrupted. Here, the pressure p.sub.b1 and the temperature T.sub.b1 (see FIG. 2), for example, may take effect in the pressure vessel.

(10) If the refueling process were now continued at another fueling pump, then it would in turn be necessary for said feed line of the other fueling pump, and at least partially the feed line of the pressure vessel, to be cooled. With the commencement of the second refueling process proceeding from the time t.sub.b2, a further additional amount of heat would thus be introduced (second hatched area), which further additional amount of heat would not be introduced in the case of a single complete refueling process without interruption (cf. FIG. 3). If refueling were now in turn performed up to the refueling end pressure p.sub.e, then the second additional amount of heat would result in an excessively high fuel temperature (for example T.sub.b3 in FIG. 2) in the pressure vessel. In accordance with the technology disclosed here, at the time t.sub.b2, the temperature difference value is determined, for example by ascertainment of the difference between the tank temperature T.sub.b2 at the time t.sub.b2 and the ambient temperature. In the present case, this temperature difference is greater than the temperature difference threshold value TD threshold, threshold, which in this case may for example amount to 10° C. Consequently, here, the second refueling process would be prevented, and a corresponding notification would be output to the driver. The driver can continue to utilize the motor vehicle with the fuel from the first refueling process, as a result of which the pressure tank cools. Here, the motor vehicle then continues to ascertain the temperature difference value TD.sub.actual TD during travel. As soon as the temperature difference value is lower than the temperature difference threshold value TD.sub.threshold, a corresponding notification is output. This may be performed, as it were, predictively. For example, provision may be made whereby the motor vehicle or the controller determines whether the temperature difference value will be lower than the temperature difference threshold value TD.sub.threshold if a filling station in the surroundings of the vehicle is traveled to.

(11) The above description of the present invention serves merely for illustrative purposes and not for the purposes of restricting the invention. Various changes and modifications are possible within the scope of the invention without departing from the scope of the invention and of its equivalents.