Method and apparatus for determining charge quantity during charging and discharging of piezoelectric elements

• US 6,539,925 B2
• Filed: 04/02/2001
• Issued: 04/01/2003
• Est. Priority Date: 04/01/2000
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Schulz, Udo, Beckert, Matthias, Rueger, Johannes-Jörg
• Primary Examiner(s): Moulis, Thomas N.
• Application Number:
  US09/824,067
• Publication Number:
  US 20010027780A1
• Time in Patent Office: 729 Days
• Field of Search: 123/497, 123/498, 123/490
• US Class Current: 123/490
• CPC Class Codes: F02D 41/2096 for controlling piezoelectric injectors drive and control circuit for piezoelectric devices in general H10N30/802
• CPC Class Codes: F02D 41/2432 Methods of calibration
• CPC Class Codes: F02D 41/2467 for injectors
• CPC Class Codes: F02D 41/2474 Characteristics of sensors
• CPC Class Codes: F02M 63/0068 Actuators specially adapted for partial and full opening of the valves

Abstract

The invention describes a method and apparatus for operating a fuel injection system having a piezoelectric element (10, 20, 30, 40, 50 or 60) for controlling the amount of fuel injected into a combustion engine, characterized in that the piezoelectric element (10, 20, 30, 40, 50 or 60) is controlled based upon the charge it is carrying.

Claims

1. A method for operating a fuel injection system having a piezoelectric element (10, 20, 30, 40, 50 or 60) for controlling the amount of fuel injected into a combustion engine characterized in that the piezoelectric element (10, 20, 30, 40, 50 or 60) is controlled based upon the charge it is carrying, and characterized in that a measured value of a current flowing into the piezoelectric element (10, 20, 30, 40, 50 or 60) is obtained and used for determining the charge the piezoelectric element (10, 20, 30, 40, 50 or 60) is carrying.

2. A method for operating a fuel injection system having a piezoelectric element (10, 20, 30, 40, 50 or 60) for controlling the amount of fuel injected into a combustion engine characterized in that the piezoelectric element (10, 20, 30, 40, 50 or 60) is controlled based upon the charge it is carrying, and characterized in that a measured value of current flowing into the piezoelectric element (10, 20, 30, 40, 50 or 60) via a current sensor is obtained.

3. Method according to claim 2, characterized in that the current sensor comprises a bridge circuit.

4. Method according to claim 2, characterized in that the current sensor is calibrated.

5. Method according to claim 2, characterized in that the measured value of the current flowing into the piezoelectric element (10, 20, 30, 40, 50 or 60) via an integrator is integrated.

6. Method according to claim 5, characterized in that the integrator is calibrated.

7. Method according to claim 6, characterized in that the integrator is calibrated using at least one of a first calibration, a second calibration and a third calibration.

8. Method according to claim 7, characterized in that the first calibration calibrates a reference voltage.

9. Method according to claim 7, characterized in that the second calibration calibrates a bridge circuit arrangement.

10. Method according to claim 7, characterized in that the third calibration calibrates a time constant of the integrator.

11. Fuel injection system having a piezoelectric element (10, 20, 30, 40, 50 or 60) for controlling the amount of fuel injected into a combustion engine, characterized in that the piezoelectric element (10, 20, 30, 40, 50 or 60) is controlled based upon the charge it is carrying, and characterized in that a measured value of a current flowing into the piezoelectric element (10, 20, 30, 40, 50 or 60) is obtained and used for determining the charge the piezoelectric element (10, 20, 30, 40, 50 or 60) is carrying.

12. A method for operating a fuel injection system having at least one piezoelectric element to control an amount of fuel to be injected into a combustion engine, the method comprising:

obtaining a measured value of a current flowing into the piezoelectric element;

determining a charge carried by the piezoelectric element in accordance with the measured value of current flowing; and

controlling the at least one piezoelectric element in accordance with the charge being carried.

13. The method according to claim 12, wherein the measured value of the current flowing is obtained in the obtaining step via a current sensor.

14. The method according to claim 13, wherein the current sensor includes a bridge circuit.

15. The method according to claim 13, further comprising:

calibrating the current sensor.

16. The method according to claim 14, further comprising:

calibrating the current sensor.

17. The method according to claim 13, further comprising:

integrating the measured current flowing into the at least one piezoelectric element via an integrator.

18. The method according to claim 17, further comprising:

calibrating the integrator.

19. The method according to claim 18, wherein the integrator is calibrated in the calibrating step using at least one of a first calibration, a second calibration, and a third calibration.

20. The method according to claim 19, wherein the first calibration includes calibrating a reference voltage.

21. The method according to claim 19, wherein the second calibration includes calibrating a bridge circuit arrangement.

22. The method according to claim 19, wherein the third calibration includes calibrating a time constant of the integrator.

23. A fuel injection system, comprising:

at least one piezoelectric element configured to control an amount of fuel to be injected into a combustion engine;

an arrangement configured to obtain a measured value of a current flowing into the piezoelectric element;

an arrangement configured to determine a charge carried by the piezoelectric element in accordance with the measured value; and

an arrangement configured to control the piezoelectric element in accordance with the charge.