Apparatus and method for a gas quantity setting system

• US 5,469,731 A
• Filed: 11/02/1993
• Issued: 11/28/1995
• Est. Priority Date: 11/02/1992
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Decker, Hans-Josef, Schwarz, Klaus-Peter
• Primary Examiner(s): Chilcot, Richard
• Assistant Examiner(s): Dombroske, George M.
• Application Number:
  US08/145,938
• Time in Patent Office: 756 Days
• Field of Search: 73/23.21, 73/23.31, 73/23.32, 73/23.33, 73/23.41, 73/863.03, 73/863.22, 73/864.81
• US Class Current: 73/23.31
• CPC Class Codes: G01M 15/102 by monitoring exhaust gases
• CPC Class Codes: G01N 1/2252 in a vehicle exhaust
• CPC Class Codes: G01N 1/24 Suction devices G01N1/22 - G01N1/2294 take precedence

Abstract

A gas quantity setting system, such as for the testing and/or certification of "low emission vehicles", provides a dilution air/exhaust gas mixture for investigation and has a continuously cross-sectionally variable, venturi nozzle and an axially adjustable conical, nozzle needle. The nozzle needle of the venturi nozzle is adjustable by a computing device, taking into consideration a temperature, a pressure and measured values of a mass rate of flow meter, in such a way that a dilution ratio (dilution factor) of the exhaust gas has a predetermined, preferably constant, value in spite of fluctuations in the feeding of quantities of exhaust gas.

Claims

1. An apparatus for a gas quantity setting system in which a mixture of dilution air and exhaust gas is sampled for analysis, the apparatus comprising:

a cross-sectionally variable, venturi nozzle, the venturi nozzle defining an axis; and

an axially adjustable, conical, nozzle needle,

wherein a position of the nozzle needle in the venturi nozzle is adjusted based on a temperature, a pressure and measured values of a mass rate of flow meter, such that a dilution ratio of the exhaust gas has a predetermined constant value despite fluctuations in quantities of exhaust gas fed to the apparatus.

2. The apparatus according to claim 1, wherein a volume of exhaust gas to be tested is continuously converted into positional changes of the nozzle to maintain a dilution ratio which is optimal for analysis.

3. The apparatus according to claim 1, wherein a total flow quantity of the system is automatically maintained in a range which is optimal for an analysis of a sample taken.

4. The apparatus according to claim 1, including a controller for setting the total flow quantity in accordance with a desired dilution rate and an actual dilution rate.

5. The apparatus according to claim 1, further comprising a fuzzy-control sub-unit for providing an advance setting of the nozzle needle position to be expected in accordance with a consideration of a behavior of the system in an event of abrupt gas quantity changes.

6. The apparatus of claim 1, further comprising a volume flow characteristic correcting device for controlling a position of the nozzle needle.

7. The apparatus of claim 1, further comprising a fuzzy-control unit for intervention in the control of the position of the nozzle needle in the event of abrupt changes in a rate of production of exhaust gas.

8. The apparatus of claim 1, further comprising an interface unit, for connecting the apparatus to a higher-level control system.

9. The apparatus of claim 1, wherein the position-controlled nozzle needle includes an axial adjustment spindle, a drive motor, a fixed bearing on the motor side and a ball-threaded bush engaging with the axial adjustment spindle.

10. The apparatus of claim 9, further comprising a guide cylinder wherein the nozzle needle is mounted axially displaceably in the guide cylinder.

11. The apparatus of claim 9, wherein the nozzle needle includes a conical diffuser adaptation section and a cylindrical run-in section, rounded at an end opposite of the conical diffuser adaptation section.

12. The apparatus of claim 11, further comprising:

a computing unit having a touch screen for entering a desired dilution factor and operating commands; and

a sub-unit for carrying out nozzle needle position correction calculations.

13. The apparatus of claim 1, further comprising a guide cylinder wherein the nozzle needle is mounted axially displaceably within said guide cylinder.

14. The apparatus of claim 1, wherein the nozzle needle includes a conical diffuser adaptation section and a cylindrical run-in section, rounded at an end opposite of the conical diffuser adaptation section.

15. The apparatus of claim 1, further comprising:

a computing unit having a touch screen for entering a desired dilution factor and operating commands; and

a sub-unit for carrying out correction calculations for positioning the nozzle needle for adaptations to measured characteristics.

16. The apparatus of claim 1, wherein the nozzle keeps a dilution factor in an optimal range for exhaust gas investigations.

17. A process for controlling a gas quantity setting system comprising the steps of:

drawing a dilution gas into a tubular flow element;

receiving an exhaust gas in said tubular flow element;

mixing said dilution gas and said exhaust gas thereby forming a mixture;

sensing a pressure and a temperature of the mixture;

sampling the mixture;

drawing the mixture toward a cross-sectionally variable venturi nozzle having an axially adjustable conical, nozzle needle; and

adjusting a position of said conical nozzle needle with respect to said venturi nozzle taking into account the sensed pressure and temperature wherein a dilution ratio of the exhaust gas has a constant value despite fluctuations in a feeding quantity of the exhaust gas.

18. The method of claim 17 further comprising the steps of:

maintaining the dilution gas in a predetermined temperature range;

measuring a mass rate of flow of the dilution gas; and

compensating for abrupt exhaust gas changes by controlling the position of the conical nozzle needle in response to fuzzy-control superpositioning dependent upon a characteristic of the nozzle and an optimal value of the dilution factor.