WO2019166181A1

WO2019166181A1 - Method and apparatus for calibrating a pulsating gas throughflow

Info

Publication number: WO2019166181A1
Application number: PCT/EP2019/052584
Authority: WO
Inventors: Thomas Fischer; Peter Maue
Original assignee: Robert Bosch Gmbh
Priority date: 2018-03-02
Filing date: 2019-02-04
Publication date: 2019-09-06
Also published as: DE102018203127A1

Abstract

The invention relates to a method for calibrating a pulsating gas throughflow, in which method - using a switching valve (2) a defined number (n) of gas pulses is introduced into a measuring chamber (1) of known volume (V), - before and after the gas pulses are introduced into the measuring chamber (1), the pressure (P_Start/Ende), the temperature (T_Start/Ende) and/or the ultrasound speed (C_Start/Ende) in the measuring chamber (1) are measured, - on the basis of the values measured and the known volume (V) of the measuring chamber (1), the particular gas mass (m_Start/Ende) is calculated, moreover using one of the following equations: a) where: Rs = special gas constant, b) where: K = adiabatic exponent, - then the gas mass (m_n) of the introduced gas pulses is calculated using the following equation: c) m_n = m_Ende ^_ m_Start and the calibration is carried out on the basis of the calculated gas mass (m_n). The invention further relates to a device for carrying out the method.

Description

description

Title:

Method and device for calibrating a pulsating gas flow

The invention relates to a method for calibrating a pulsating Gasdurchflus ses with the features of the preamble of claim 1. Furthermore, the invention relates to a device for carrying out the method according to the invention.

State of the art

The published patent application DE 10 2015 219 236 A1 discloses a device and a method for measuring the flow rate of a gas injector, the method being carried out by means of the device. The device comprises a measuring chamber for at least indirect arrangement on an outlet region of the gas injector, a valve device, by means of which an outlet cross section of the measuring chamber and the pressure prevailing in the measuring chamber are adjustable, and measuring means for detecting prevailing in the measuring chamber parameters of the gas. Even with a rela tively low number of gas injections or a few strokes of the gas injector, ide alally already in a single injection, the gas injector abge given amount of gas or gas mass to determine highly accurate, the Venti leinrichtung the device is designed to Completely close the outlet cross-section of the measuring chamber. The required measurements can thus be carried out in a closed volume, so that the parameters occurring in a single Gasein blasung, changing in the measuring chamber parameters are particularly easy, accurate and effectively measurable.

Based on the above-mentioned prior art, the present invention has the object to further increase the accuracy of measurement in the calibration of a pul sierenden gas flow. The object is achieved by the method having the features of claim 1 as well as by the device having the features of claim 8. Advantageous developments of the invention Weiterbil are to be found in the respective subclaims.

Disclosure of the invention

Proposed is a method for calibrating a pulsating Gasdurchflus ses, in which

- using a switching valve, a defined number (n) of gas pulses in a measuring chamber of known volume (V) is initiated,

- the pressure (ps _tari / _end ), the temperature (Ts _tad / _end ) and / or the ultrasonic speed (cs _tad / _end ) in the measuring chamber are measured before and after the introduction of the gas pulses into the measuring chamber,

- Based on the measured values and the known volume (V) of the Messkam mer the respective gas mass (ms _tad / _end ) is calculated, according to one of the following equations: ^a ) tn _St ar _{tl end} = ^Pstart _r ^{end V} with : R _s = special gas constant

^' Start i End ^b ) ^m Start _/ End = ^KP ₂ ^{s, art} ' ^{End V} with: K = adiabatic exponent,

^ Start l end

- Then the gas mass (m _n ) of the introduced gas pulses is calculated according to the following equation:

^C ) ^m n = ^m end - ^m start

- and on the basis of the calculated gas mass (m _n ) the calibration is performed.

By means of the switching valve, a pulsating gas flow between the Messkam mer and a gas line can be switched. This has the advantage over direct injection into the measuring chamber that the n-weft can reach a stable state even before it is introduced into the measuring chamber. Consequently, there is also in the measuring chamber a largely balanced in terms of pressure and / or temperature ner state. On the other hand, if a large number of individual gas quantities are injected into a measuring chamber by means of a gas injector, usually high frequencies of up to approximately 100 Hz being achieved, a state is achieved in the measuring chamber which is neither balanced with respect to pressure nor temperature. This can lead to measurement errors. To correct such measurement errors, a calibration can be carried out according to the method according to the invention. The method according to the invention therefore represents a helpful supplement to the method mentioned above for measuring the flow rate of a gas injector.

The answer to the question as to whether the calculations to be performed are based on equation (a) or equation (b) depends on the pressure increase in the measuring chamber. This in turn depends on the volume of the measuring chamber and the amount of gas introduced. If the pressure increase is small, for example in the range between 0 and 1 bar rel., The equation (a) valid for ideal gases can be used. At a higher pressure increase, the equation (b) valid for real gases is preferably used.

In the method according to the invention is preferably the number (n) of the gas pulses 100 to 100,000, preferably 1,000 to 10,000. This means that a comparatively large amount of gas is introduced into the measuring chamber and collected there. State variables, such as, for example, the pressure (p) and the temperature (T) in the measuring chamber, can be measured particularly easily and thus particularly accurately in this way. The measurement accuracy can thus be further improved.

Further preferably, the gas pulses in a measuring chamber with a Volu men (V) of 0.1 1 to 10,000 I, preferably from 0.3 to 2,000 I, further preference, from 3 I to 250 I initiated. This means that even with a very large number (n) of gas pulses that are introduced into the measuring chamber, the pressure (p) in the measuring chamber increases only slightly. Accordingly, the equation (a) valid for ideal gases can be used to calculate the gas masses (mstad / end).

The calculation of the respective gas masses (mstad / end) is preferably based on a volume (V), the surcharges for accessories connected to the measuring chamber. and / or derivatives. This is particularly relevant if the supply and / or discharge have a volume that is greater than a desired tolerances Tole. Furthermore, it is proposed that the volume (V) comprises reductions for measuring means arranged in the volume (V). This means that the actual volume (V) is determined and based on the calculations. In this way, the accuracy in determining the gas masses (ms _tar V _end ) can be increased.

In a further development of the invention, it is proposed that the pressure (pEnde), the temperature (T _end ) and / or the ultrasonic speed (c _end ) of the gas pulses conducted into the measuring chamber are measured only after a transient phase has elapsed. This measure ensures that the state in the measuring chamber is substantially equalized in terms of pressure and / or temperature when carrying out the required measurements.

The measured values determined during the measurements are preferably directed to a control and / or evaluation device. In this the equations a) to c) can be deposited, so that on the basis of which the gas mass (m _n ) can be calculated. Furthermore, the switching valve is preferably actuated by means of the control and / or evaluation unit in order to introduce a defined number (n) of gas pulses into the measuring chamber.

Before carrying out a further calibration process, the overpressure generated in the measuring chamber by introducing the gas pulses is preferably reduced. This means that the initial state is restored in the measuring chamber. For this purpose, the switching valve or another valve is opened to let off gas from the measuring chamber.

The moreover for the implementation of the method according to the invention proposed gene includes device

a measuring chamber of known volume (V),

- A switching valve, by means of which a defined number (n) of gas pulses can be introduced immediacy bar or indirectly via a supply line into the measuring chamber, and

- Measuring means comprising at least one sensor. The measuring means may in particular be a duck, temperature and / or ultrasonic sensor. If the measuring instruments are arranged in the measuring chamber, the volume (V) decreases accordingly. The supply and / or discharge lines connected to the measuring chamber increase the volume (V). The volume (V) is therefore the actual volume behind the diverter valve. This is assumed to be known.

The switching valve, which serves to introduce a defined number (n) of gas pulses into the measuring chamber, is preferably designed as a 3/2-way valve. The measuring chamber or a supply line connected to the measuring chamber can be connected in this way with a gas line, via which the device, a gas quantity can be supplied, which corresponds to a defined number (n) of gas pulses. In contrast to Direk teinblasung in the measuring chamber can be achieved in this way from the beginning of a comparatively stable state in terms of pressure and temperature in the measuring chamber. Further, by switching the switching valve again, a self-contained volume (V) can be created, which promotes rapid stabilization.

Advantageously, the at least one sensor is connected via a signal line to a control and / or evaluation device. The measured values recorded by the sensor can then be passed to the control and / or evaluation device for evaluation or for controlling the device, in particular the measuring element and / or the switching valve.

Furthermore, it is proposed that the device is connected to a device to be calibrated in order to carry out the desired calibration. As a result of the comparatively large measuring chamber, the increase in pressure caused by the introduction of the gas pulses can be set to a small amount, so that a very accurate calculation of the correction factor is possible.

The invention will be explained in more detail with reference to the accompanying drawings. These show:

1 is a schematic representation of an inventive device for Ka calibration of a pulsating gas flow, Fig. 2 is a schematic representation of an extended device and

Fig. 3 is a schematic representation of the device of Fig.l in combination with a device for flow measurement of a gas injector.

Detailed description of the drawings

1 shows a device 10 for calibrating a pulsating gas flow with a measuring chamber 1 and a switching valve 2, by means of which the measuring chamber 1 or a ver with the measuring chamber 1 bound supply line 3 with a gas line 9 is connectable. In this way, the measuring chamber 1, a quantity of gas can be supplied, which corresponds to a defined number (n) of gas pulses. To the measuring chamber 1, a derivative 4 is further connected with a Ven valve 12, via which gas can be discharged from the measuring chamber 1 to - after the measurement - grow a pressure generated in the measuring chamber 1.

In the measuring chamber 1 measuring means in the form of a pressure sensor 6, a tempera ture sensor 7 and another sensor 8 are added, wherein it may be, for example, an ultrasonic sensor in the further sensor 8. By means of the sensors 6, 7, 8, the corresponding state variables, in particular the pressure p and the temperature T in the measuring chamber 1 can be detected. The sensors 6,

7, 8 are connected via signal lines 11 to a control and evaluation device 5, in which on the basis of the measured by the sensors 6, 7, 8 measured values and the volume V of the measuring chamber 1, the gas mass m _{n is} calculated.

As shown in FIG. 2, the device 10 can be connected to a calibration device 14 via a gas line, preferably the gas line 9, and a synchronization line 13 in order to carry out a corresponding calibration in the event of a detected deviation.

In Fig. 3, the device 10 is shown in combination with the device 20 for measuring the flow rate of a gas injector known from the prior art. By means of the device 10, a calibration of the device 20 can be performed. For this purpose, the gas line 9 is connected to the output of the valve device 17 of the device 20 Vorrich. Via the valve device 17, the gas line 9 with a measuring chamber 19 of the device 20 is connected, into which by means of a gas injector 15 gas is blown. By means of the switching valve 2, the amount of gas is introduced from a defined number of pulses n in the measuring chamber 1 of the device 10 to the

Gas mass m _n to determine. If a deviation is detected, calibration can be carried out by means of the device 10. For this purpose, the device 10 is connected via a synchronization line 18 to a control and evaluation unit 16 of the device 20 Vorrich.

Claims

claims

1. A method for calibrating a pulsating gas flow, wherein

- using a switching valve (2) a defined number (n) of gas pulses in a measuring chamber (1) of known volume (V) is initiated,

- Before and after the introduction of the gas pulses into the measuring chamber (1) the pressure

(pstari / end), the temperature (Tstad / end) and / or the ultrasonic velocity (cstad / end) are measured in the measuring chamber (1),

- based on the measured values and the known volume (V) of the measuring chamber (1) the respective gas mass (ms _tad / _end ) is calculated, according to one of the following equations: ^a ) tn _St ar _{tl end} = ^Pstart _r ^{end V} with: R _s = special gas constant

^' Start i end ^b ) with: K = adiabatic exponent,

^C ) ^m n = ^m end - ^m S, ar,

and the calibration is performed based on the calculated gas mass (m _n ).

2. The method according to claim 1,

characterized in that the number (n) of the gas pulses is 100 to 100,000, preferably 1,000 to 10,000.

3. The method according to claim 1 or 2,

characterized in that the gas pulses in a measuring chamber (1) having a volume (V) of 0.1 1 to 10,000 I, preferably from 0.3 to 2,000 I, further preferably from 3 I to 250 I are introduced.

4. The method according to any one of the preceding claims,

characterized in that in the calculation of the respective gas masses (mstari / end) is based on a volume (V), the surcharges for with the measuring chamber (1) connected to and / or discharges (3, 4) and / or deductions for in lumen (V) arranged measuring means comprises.

5. Method according to one of the preceding claims,

characterized in that the pressure (p _end ), the temperature (T _end ) and / or the ultrasonic velocity (c _end ) of the introduced into the measuring chamber (1) gas pulses are measured only after a transient phase, so that the state in the measuring chamber (1) is substantially balanced in terms of pressure and / or temperature.

6. The method according to any one of the preceding claims,

characterized in that the measured values are conducted to a control and / or Auswerteein direction (5), by means of which preferably the gas mass (m _n ) is calculated according to the equations a) to c).

7. The method according to any one of the preceding claims,

characterized in that before the implementation of a further Kalibriervor gangs in the measuring chamber (1) generated by introducing the gas pulses overpressure is reduced.

8. Device (10) for carrying out the method according to one of the preceding claims, comprising

a measuring chamber (1) of known volume (V),

- A switching valve (2), by means of which a defined number (n) of gas pulses immedi applicable or indirectly via a feed line (3) into the measuring chamber (1) can be introduced, and

- Measuring means comprising at least one sensor (6, 7, 8).

9. Device (10) according to claim 8,

characterized in that the switching valve (2) for connecting the measuring chamber (1) or one with the measuring chamber (1) connected to the supply line (3) with a gas line (9) is designed as a 3/2-way valve.

10. Device (10) according to claim 8 or 9,

characterized in that the at least one sensor (6, 7, 8) is connected via a signal line (11) to a control and / or evaluation device (5).

11. Device (10) according to one of claims 8 to 10,

characterized in that the device (10) is connected with a device to be calibrated.