Method, computer program, and device for measuring the amount injected by an injection system

• US 20030177823A1
• Filed: 05/05/2003
• Published: 09/25/2003
• Est. Priority Date: 03/06/2001
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Braun, Hans, Seidel, Josef, Schoeffel, Eberhard
• Granted Patent: US 6,915,683 B2
• Time in Patent Office: Days
• US Class Current: 73/118.2
• CPC Class Codes: F02M 65/001 Measuring fuel delivery of a fuel injector

Abstract

For measuring the injection quantity (Vm) of injection systems (18), in particular in internal combustion engines, test fluid (22) is injected by the injection system (18) into a measurement chamber (12). To increase the precision and stability of the measurement, the volume of the measurement chamber (12) is kept constant during the injection. Moreover, a gas volume (Vg) is present in the measurement chamber (12). The injected volume (Vm) of test fluid (22) is ascertained from the pressure change (dP) in the measurement chamber (12) that occurs upon an injection of test fluid (22). The ascertainment of the injected volume (Vm) is done by means of the state equation for ideal gases. (FIG. 1)

Claims

1. A method for measuring the injection quantity (Vm) of injection systems (18), in particular in internal combustion engines, in which a test fluid (22) is injected by the injection system (18) into a measurement chamber (12), characterized in that the volume of the measurement chamber (12) is constant during the injection;

a gas volume, preferably an air volume(Vg)is present in the measurement chamber(12); and

the injected volume (Vm) of test fluid (22) is ascertained, by means of the state equation for ideal gases, from the pressure change (dP) in the measurement chamber (12) that results upon an injection.

2. The method of claim 1, characterized in that before an injection, the volume of the measurement chamber (12), closed off in gastight fashion, is varied by a defined amount, and from the resultant pressure change, the gas volume (Vg) in the measurement chamber (12) is ascertained.

3. The method of one of claims 1 or 2, characterized in that the temperature (Tg) of the gas (24) and/or of the test fluid (22) in the measurement chamber (12) is detected and taken into account in ascertaining the injected volume (Vm) of test fluid (22).

4. The method of one of the foregoing claims, characterized in that a temperature increase (dT) of the injected test fluid (22) is ascertained from the difference between the pressure (Pg) that prevails in the injection system and the pressure (Ph) in the measurement chamber (12).

5. The method of one of the foregoing claims, characterized in that the measurement chamber (12) is flushed with a gas, preferably air, before a measurement.

6. The method of one of the foregoing claims, characterized in that the flow of test fluid in the injection is made uniform and/or slowed down.

7. The method of one of the foregoing claims, characterized in that the measurement chamber (12) includes a wire mesh (13).

8. The method of one of the foregoing claims, characterized in that the pressure increase, caused by a temperature increase in the measurement chamber (12), is described by an exponential function, which is proportional to the injected volume (Vm) or to the measured pressure change (dP).

9. A computer program, characterized in that it is suitable for performing the method of one of the foregoing claims, when it is executed on a computer.

10. The computer program of claim 9, characterized in that it is stored in a memory, in particular a flash memory.

11. An apparatus for measuring the injection quantity of injection systems (18), in particular in internal combustion engines, having a measurement chamber (12) and a connecting device (16), by means of which an injection system (18) can be made to communicate with the measurement chamber (12);

having a pressure sensor (26), which detects the pressure (Pg) in the measurement chamber (12); and

having a processing device (44), which processes the measurement signal furnished by the pressure sensor(26), characterized in that the measurement chamber(12) is embodied such that its volume can be kept constant during the injection;

a gas volume, preferably an air volume (Vg), is present in the measurement chamber (12); and

the processing device (44) is embodied such that it ascertains the injected volume (Vm) of test fluid (22) from the measurement signal of the pressure sensor (26) before and after the injection, by means of the state equation for ideal gases.

12. The apparatus of claim 11, characterized in that it includes a piston (38), which is displaceable in a defined manner and which regionally defines the measurement chamber (12).

13. The apparatus of one of claims 11 or 12, characterized in that it includes a gas supply, preferably a compressed-air source (32), which can be made to communicate with the measurement chamber (12).

14. The apparatus of one of claims 11-13, characterized in that it includes a porous body, preferably a sintered body (48), which is disposed such that eddies in the measurement chamber (12) upon an injection of test fluid (22) are averted.

15. The apparatus of claim 14, characterized in that the measurement chamber (12) is embodied in the porous body (48).

16. The apparatus of one of claims 11-15, characterized in that it includes a temperature sensor (28), which detects the temperature (Tg) of the gas and/or of the fluid in the measurement chamber (12).

17. The apparatus of one of claims 11-16, characterized in that the processing device (44) is provided with a computer program of one of claims 6 or 7.