Method for controlling a control valve

Abstract

A method for controlling a control valve, the control valve controlling a volume flow of a fluid along a line, the method including at least the following steps: (a) performing a closing operation of the control valve; (b) measuring a pressure profile upstream of the control valve; and (c) determining a density of the fluid.

Claims

1. A method for controlling a control valve, the control valve controlling a volume flow of a fluid along a line, the method comprising at least the following steps performed in the following order: a) measuring at least a minimum of a pressure profile upstream of the control valve while the control valve is at least partially open, the measuring occurring immediately prior to the control valve being closed; b) performing a closing operation on the control valve, while the control valve is at least partially open, to yield a closed control valve; c) measuring at least a maximum of a pressure profile upstream of the closed control valve immediately after the control valve is closed; and d) determining a density of the fluid based on both the minimum of the pressure profile upstream of the control valve while the control valve is at least partially open and the maximum of the pressure profile upstream of the closed control valve.

2. The method as recited in claim 1, wherein measuring the minimum of the pressure profile includes measuring the volume flow of the fluid streaming over the at least partially open control valve.

3. The method as recited in claim 2, further comprising, based on the density and the volume flow of the fluid, determining at least a first amount of a first component of the fluid and a second amount of a second component of the fluid.

4. The method as recited in claim 3, wherein the first component is air, and the second component is a fuel.

5. The method as recited in claim 1, further comprising measuring a temperature of the fluid, wherein the determination of the density of the fluid is additionally based on the temperature.

6. The method as recited in claim 1, wherein the control valve opening and closing occurs at a definable frequency, wherein steps a) through d) are carried out during at least two successive closing operations.

7. The method as recited in claim 6, wherein the frequency is between 5 and 50 Hertz.

8. The method as recited in claim 1, wherein the control valve controls the volume flow of the fluid from a filter of a tank to an intake manifold of a combustion engine, and an addition of fuel to the combustion engine is controlled as a function of the density of the fluid.

9. The method as recited in claim 1, further comprising calculating an amount of fuel to be injected into a combustion engine based on a density of air, a density of the fuel, and the determined density of the fluid.

10. A motor vehicle comprising: a combustion engine having at least a combustion chamber; a tank, which is provided for a fuel that is reactable in the combustion engine and which has a filter; an intake manifold, via which at least air and the fuel may be supplied to the combustion chamber; a control valve that controls a volume flow of a fluid along a line, wherein the fluid includes the fuel from the filter to the intake manifold; a pressure sensor for measuring at least a minimum and a maximum of a pressure profile upstream of the control valve; and a processor configured to perform the following in the following order: measure at least a minimum of the pressure profile upstream of the control valve while the control valve is at least partially open, the measure occurring immediately prior to the control valve being closed, a closing operation on the control valve, while the control valve is at least partially open, to yield a closed control valve, measure at least a maximum of the pressure profile upstream of the closed control valve immediately after the control valve is closed, and determine a density of the fluid based on both the minimum of the pressure profile upstream of the control valve while the control valve is at least partially open and the maximum of the pressure profile upstream of the closed control valve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention, as well as the technical field are explained in greater detail in the following with reference to the enclosed figures. It should be noted that the present invention is not to be limited by the cited exemplary embodiments. In particular, unless explicitly described otherwise, it is also possible to extract partial aspects of the subject matter explained in the figures and to combine them with other elements and realizations from the present description. It should be noted, in particular that the figures and, in particular the illustrated relative sizes are only schematic.

(2) FIG. 1 shows a motor vehicle; and

(3) FIG. 2: shows a variant of the method.

DETAILED DESCRIPTION OF THE INVENTION

(4) FIG. 1 shows a motor vehicle 11. Motor vehicle 11 includes a combustion engine 7 having a plurality of combustion chambers 12, a tank 5 which is provided for a fuel 10 that is reactable in combustion engine 7 and which has a filter 4, an intake manifold 6, via which at least air and fuel 10 may be supplied to combustion chamber 12, as well as a control valve 1 that controls a volume flow 2 of fluid 3 that includes fuel 10 from filter 4 via lines 16, 17 to intake manifold 6. A control unit 14 is able to control the opening and closing of control valve 1. Control unit 14 is adapted or suitably designed for implementing the method.

(5) Directly upstream of control valve 1, motor vehicle 11 also includes a pressure sensor 13 via which pressure 18 or pressure profile 9 is measurable upstream of control valve 1.

(6) Fuel 10 is stored in a tank 5, it being possible for fuel vapors to reach filter 4 via first line 16. Fuel 10 temporarily stored in filter 4 is transferred via control valve 1 and via second line 17 to intake manifold 6.

(7) FIG. 2 shows a variant of the method in a diagram. Pressure 18, which is measured by pressure sensor 13 (directly) upstream of control valve 1, is plotted on the vertical axis. Time 15 is plotted on the horizontal axis.

(8) A closing operation 8 of control valve 1 is performed in accordance with step a). Pressure profile 9 is measured upstream of control valve 1 in accordance with step b). A density of fluid 3 is determined in accordance with step c).

(9) Control valve 1 is operated at one frequency, and opens and closes in the frequency (here, the frequency is 10 Hertz). The method is performed here for four successive closing operations 8.

(10) During open phase 19 of control valve 1, a flow of fluid 3 forms. If control valve 1 then closes (closing operation 8, transition to closed phase 20), volume flow 2 of fluid 3 is abruptly interrupted. This leads to a measurable pressure rise upstream of control valve 1. The profile of the pressure rise (thus, pressure profile 9) or the pressure variation (respectively, measured pressure difference 21) is a function of the velocity of volume flow 2 during open phase 19 and of the density of fluid 3. The illustrated undulation of pressure profile 9 represents the pressure variation upstream of control valve 1 that is caused by closing operation 8.

(11) The density of fluid 3 may be determined by pressure sensor 13, respectively with the additional determination of the temperature. The amounts of air and fuel 10 may be determined from the generally known single density values (density of fuel 10 being used and density of the air, possibly determined as a function of temperature) and the measured (total) density of fluid 3.

(12) The described method makes it possible to determine the amount of fuel 10 or the amount of fuel 10 coming from filter 4, this amount already being measured upstream of combustion chamber 12. Consequently, the addition of fuel to combustion engine 7 may be controlled already before fuel 10 is combusted.

REFERENCE NUMERAL LIST

(13) 1 control valve 2 volume flow 3 fluid 4 filter 5 tank 6 intake manifold 7 combustion engine 8 closing operation 9 pressure profile 10 fuel 11 motor vehicle 12 combustion chamber 13 pressure sensor 14 control unit 15 time 16 first line 17 second line 18 pressure 19 open phase 20 closed phase 21 pressure difference