Method for operating a drive system of a motor vehicle, drive system and motor vehicle

Abstract

A method for operating a drive system of a motor vehicle having a combustion engine, a fuel tank, and an evaporative emission control system, includes the following steps: opening a canister-purge valve of the evaporative emission control system; using a first sensor of the motor vehicle designed as a pressure sensor to ascertain an evaporative emission control system pressure prevailing in the evaporative emission control system between a filter device of the evaporative emission control system and the canister-purge valve; using a measurement device of the motor vehicle to ascertain an ambient pressure of the motor vehicle; using a computational device of the motor vehicle to compute a flow volume of a fluid streaming through the canister-purge valve on the basis of the ascertained evaporative emission control system pressure and the ascertained ambient pressure; and using an engine control device of the drive system of the motor vehicle to operate the drive system taking into account the computed fluid flow volume.

Claims

1. A method for operating a drive system of a motor vehicle having a combustion engine, a fuel tank, and an evaporative emission control system, comprising the following steps: opening a canister-purge valve of the evaporative emission control system; using a first sensor of the motor vehicle designed as a pressure sensor to ascertain an evaporative emission control system pressure prevailing in the evaporative emission control system between a filter device of the evaporative emission control system and the canister-purge valve; using a measurement device of the motor vehicle to ascertain an ambient pressure of the motor vehicle; using a computational device of the motor vehicle to compute a flow volume of a fluid streaming through the canister-purge valve on the basis of the ascertained evaporative emission control system pressure and the ascertained ambient pressure; and using an engine control device of the drive system of the motor vehicle to operate the drive system taking into account the computed fluid flow volume.

2. The method as recited in claim 1, wherein a second sensor designed as a pressure sensor is used as the measurement device.

3. The method as recited in claim 1, wherein Bernoulli's equation is used to compute the flow volume of the fluid streaming through the canister-purge valve.

4. The method as recited in claim 1, wherein: a temperature of the fluid flowing through the canister-purge valve is ascertained by a third sensor designed as a temperature sensor; a density of the fluid is determined on the basis of the ascertained temperature; the mass flow of the fluid streaming through the canister-purge valve is computed on the basis of the ascertained volume flow and the determined density; and the drive system is operated by the engine control device taking into account the computed mass flow.

5. A drive system for a motor vehicle, comprising: a combustion engine, an engine control device, a fuel tank having an evaporative emission control system, a controllable canister-purge valve for venting the fuel tank, and a measurement device for ascertaining an ambient pressure of the motor vehicle, wherein the drive system has a first sensor designed as a pressure sensor for ascertaining an evaporative emission control system pressure prevailing in the evaporative emission control system between a filter device of the evaporative emission control system and the canister-purge valve, as well as a computational device for computing a flow volume of a fluid streaming through the canister-purge valve on the basis of the ascertained ambient pressure and the ascertained evaporative emission control system pressure.

6. The drive system as recited in claim 5, wherein the drive system is designed for implementing a method comprising the following steps: opening a canister-purge valve of the evaporative emission control system; using a first sensor of the motor vehicle designed as a pressure sensor to ascertain an evaporative emission control system pressure prevailing in the evaporative emission control system between a filter device of the evaporative emission control system and the canister-purge valve; using a measurement device of the motor vehicle to ascertain an ambient pressure of the motor vehicle; using a computational device of the motor vehicle to compute a flow volume of a fluid streaming through the canister-purge valve on the basis of the ascertained evaporative emission control system pressure and the ascertained ambient pressure; and using an engine control device of the drive system of the motor vehicle to operate the drive system taking into account the computed fluid flow volume.

7. The drive system as recited in claim 5, wherein the first sensor is integrated in the canister-purge valve of the evaporative emission control system.

8. The drive system as recited in claim 5, wherein the measurement device is designed as a second sensor, the second sensor being designed as a pressure sensor.

9. The drive system as recited in claim 5, wherein the evaporative emission control system has a third sensor designed as a temperature sensor, the first sensor and the third sensor being designed as a common sensor.

10. A motor vehicle, comprising a drive system, wherein the drive system is designed in accordance with claim 5.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A method according to the present invention for operating a drive system of a motor vehicle, a drive system according to the present invention for a motor vehicle, as well as a motor vehicle according to the present invention are clarified in greater detail in the following with reference to the drawing. The figures show schematically:

(2) FIG. 1 is a design of a preferred specific embodiment of a drive system according to the present invention;

(3) FIG. 2 is a side view of a preferred specific embodiment of a motor vehicle according to the present invention; and

(4) FIG. 3 is a flow chart of a preferred specific embodiment of a method according to the present invention.

(5) Elements having the same function and mode of operation are provided with the same reference numerals in FIG. 1 through 3.

DETAILED DESCRIPTION OF THE INVENTION

(6) FIG. 1 schematically illustrates a design of a preferred specific embodiment of a drive system 1 according to the present invention. Drive system 1 includes a combustion engine system 27, a fuel tank 4 and an evaporative emission control system 5.

(7) Combustion engine system 27 has an air filter 23 for filtering induced fresh air. The fresh air may be supplied via an intake pipe 17 into a compressor 22 of an exhaust turbocharger 28 and is compressible there. The fresh air may be supplied to a combustion engine 3 of combustion engine system 27 via intake pipe 17 and a throttle valve 21. The exhaust gases may be directed out of combustion engine 3 via an exhaust line and fed into a turbine 24 of exhaust turbocharger 28 to drive compressor 22. Configured downstream of turbine 24 is a lambda probe for measuring emission levels.

(8) Gaseous fuel may be fed via a vent line 14 of evaporative emission control system 5 from fuel tank 4 into a filter device 7 of evaporative emission control system 5. Via a supply air line 15 of evaporative emission control system 5, ambient air may be fed into filter device 7 and filtered by the same. For this purpose, filter device 7 preferably has an activated-carbon filter. A mixture of gaseous fuel and the filtered ambient air may be produced in filter device 7. The mixture may be fed as a fluid flow volume via vent line 14 through a canister-purge valve 6 of evaporative emission control system 5. A volumetric fluid flow rate is controllable via canister-purge valve 6.

(9) A first sensor 8 designed as a pressure sensor, which, in addition, is designed as third sensor 13 for measuring a temperature of the fluid flow volume, is configured upstream of canister-purge valve 6. In an alternative specific embodiment of the present invention, the need may also be eliminated for third sensor 13, so that only a first sensor 8 is located at this position. Following canister-purge valve 6, a fluid supply line 16 of evaporative emission control system 5 is configured downstream of throttle valve 21 to feed a portion of the fluid flow volume via a first non-return valve into intake pipe 17. In accordance with this preferred exemplary embodiment, evaporative emission control system 5 is also designed to supply the other portion of the fluid flow volume via a fluid supply line 16, as well as via a venturi tube 20 to intake pipe 17 between air filter 23 and compressor 22. A fuel supply device for supplying liquid fuel to intake pipe 17 is preferably provided in accordance with the present invention, but not shown in FIG. 1 for the sake of improved clarity.

(10) FIG. 2 schematically shows a side view of a preferred specific embodiment of a motor vehicle 2 according to the present invention having a drive system 1 according to the present invention. Components of drive system 1 configured inside of motor vehicle 2 are only indicated by dashed lines and, in accordance with the present invention, may also be configured at other locations of the motor vehicle. Drive system 1 includes a combustion engine 3, an engine control device 11, a fuel tank 4, as well as an evaporative emission control system 5. A computational device 10 is designed as part of engine control device 11. A fuel supply device for supplying liquid fuel to intake pipe 17 is preferably provided in accordance with the present invention, but not shown in FIG. 2 for the sake of improved clarity.

(11) Evaporative emission control system 5 has a canister-purge valve 6, a first sensor 8 designed as a pressure sensor, a filter device for filtering induced ambient air and a measurement device 9. First sensor 8 is also designed as third sensor 13 for measuring temperature. In this exemplary embodiment, measurement device 9 is designed as second sensor 12 for measuring pressure.

(12) In a flow chart, FIG. 3 schematically illustrates a preferred specific embodiment of a method according to the present invention. A canister-purge valve 6 of evaporative emission control system 5 is opened in a first method step 100. The opening may be carried out completely or partially. It is preferably engine control device 11 of inventive drive system 1 of inventive motor vehicle 2 that actuates the opening of canister-purge valve 5. In a second method step 200, an evaporative emission control system pressure prevailing in evaporative emission control system 5 between filter device 7 of evaporative emission control system 5 and canister-purge valve 6 is ascertained by first sensor 8 of motor vehicle 2 that is designed as a pressure sensor. The ascertained evaporative emission control system pressure is preferably transmitted to computational device 10, in particular of engine control device 11. In a third method step 300, the ambient pressure of motor vehicle 2 is ascertained by measurement device 9 of motor vehicle 2. For this, measurement device 9 is preferably designed as second sensor 12, second sensor 12 being designed as a pressure sensor. The ascertained ambient pressure is preferably transmitted to computational device 10, in particular of engine control device 11. In a fourth method step 400, the flow volume of the fluid streaming through canister-purge valve 6 is computed by computational device 10 on the basis of the ascertained evaporative emission control system pressure and the ascertained ambient pressure. The computations are preferably based on a Bernoulli equation, as well as on a principle of conservation of energy. In a fifth method step 500, inventive drive system 1 is operated by engine control device 11, taking the computed fluid flow volume into account. In an alternative embodiment of the method according to the present invention, a temperature of the fluid is ascertained by a third sensor 13 designed as a temperature sensor. For this, first sensor 8 is preferably designed as third sensor 13, thus as a dual sensor. Engine control device 11 computes a fluid mass flow on the basis of the temperature and the fluid flow volume. Engine control device 11 then uses the fluid mass flow as a basis for operating drive system 1.

REFERENCE NUMERAL LIST

(13) 1 drive system 2 motor vehicle 3 combustion engine 4 fuel tank 5 evaporative emission control system 6 canister-purge valve 7 filter device 8 first sensor 9 measurement device 10 computational device 11 engine control device 12 second sensor 13 third sensor 14 vent line 15 supply air line 16 fluid supply line 17 intake pipe 18 first non-return valve 19 second non-return valve 20 venturi tube 21 throttle valve 22 compressor 23 air filter 24 turbine 25 exhaust line 26 lambda probe 27 combustion engine system 28 exhaust turbocharger 100 first method step 200 second method step 300 third method step 400 fourth method step 500 fifth method step