Method and control unit for calibrating a drive of a throttle valve of an internal combustion engine in a motor vehicle

Abstract

A method for calibrating a drive of a throttle valve of an internal combustion engine of a motor vehicle includes detecting whether the internal combustion engine is currently running or is not running. The method further includes activating the drive to displace the throttle valve into a target position if it is detected that the internal combustion engine is currently not running. The method further includes calibrating a characteristic at the target position. A correlation between a rotor position of the drive and an output voltage of a throttle valve angle transducer follows a characteristic.

Claims

1. A method for calibrating a drive of a throttle valve of an internal combustion engine of a motor vehicle, a rotor position of the drive and an output voltage of a throttle valve angle transducer having a characteristic correlation, the method comprising: detecting whether the internal combustion engine is running; in response to detecting that the internal combustion engine is running, (i) commanding the drive to displace the throttle valve into at least one first target position according to driver throttle commands, and (ii) calibrating the characteristic correlation based on the commanded at least one first target position and the corresponding output voltage of the throttle valve angle transducer; and in response to detecting that the internal combustion engine is not running, (i) commanding the drive to displace the throttle valve into at least one second target position, which is independent of driver throttle commands, and (ii) calibrating the characteristic correlation based on the commanded at least one second target position and the output voltage of the throttle valve angle transducer.

2. The method as claimed in claim 1, wherein the first target position is in a region in which the throttle valve is displaced according to current driver throttle commands.

3. The method as claimed in claim 1, wherein the second target region is outside a region in which the throttle valve is displaced according to current driver throttle commands.

4. The method as claimed in claim 1, wherein the drive of the throttle valve includes a brushless direct current motor.

5. A control unit for a motor vehicle, wherein the control unit is configured to perform a method, a rotor position of the drive and an output voltage of a throttle valve angle transducer having a characteristic correlation, the method including: detecting whether the internal combustion engine is running; in response to detecting that the internal combustion engine is running, (i) commanding the drive to displace the throttle valve into at least one first target position according to driver throttle commands, and (ii) calibrating the characteristic correlation based on the commanded at least one first target position and the corresponding output voltage of the throttle valve angle transducer; and in response to detecting that the internal combustion engine is not running, (i) commanding the drive to displace the throttle valve into at least one second target position, which is independent of driver throttle commands, and (ii) calibrating the characteristic correlation based on the commanded at least one second target position and the output voltage of the throttle valve angle transducer.

6. The control unit as claimed in claim 5, wherein the control unit is included in a motor vehicle.

7. The control unit as claimed in claim 6, wherein the motor vehicle comprises a start-stop system.

8. The control unit as claimed in claim 6, wherein the motor vehicle is a hybrid vehicle configured to be driven using an auxiliary motor when the internal combustion engine is not running.

9. A computer program product, comprising computer-readable instructions that instruct the computer program product when run on a programmable control unit to perform a method, a rotor position of the drive and an output voltage of a throttle valve angle transducer having a characteristic correlation, the method including: detecting whether the internal combustion engine is running; in response to detecting that the internal combustion engine is running, (i) commanding the drive to displace the throttle valve into at least one first target position according to driver throttle commands, and (ii) calibrating the characteristic correlation based on the commanded at least one first target position and the corresponding output voltage of the throttle valve angle transducer; and in response to detecting that the internal combustion engine is not running, (i) commanding the drive to displace the throttle valve into at least one second target position, which is independent of driver throttle commands, and (ii) calibrating the characteristic correlation based on the commanded at least one second target position and the output voltage of the throttle valve angle transducer.

10. The computer program product as claimed in claim 9, wherein the computer program product is stored on a computer-readable medium.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the disclosure are described below with reference to the accompanying figures, wherein neither the figures nor the description are designed to limit the disclosure.

(2) FIG. 1 shows an arrangement with a throttle valve controlled by means of a control unit, with which the method according to the disclosure can be implemented.

(3) FIG. 2 shows a flow chart for illustrating a method according to the disclosure.

(4) The figures are only schematic and not to scale.

DETAILED DESCRIPTION

(5) Embodiments of a calibration method according to the disclosure and of a control unit implementing such a method are described below with reference to the structure shown in FIG. 1 and with reference to the flow chart shown in FIG. 2.

(6) As shown in FIG. 1, a motor vehicle typically comprises an internal combustion engine 9 to which air is fed by means of an induction pipe 13. One or a plurality of throttle valves 1 is/are disposed in the induction pipe 13. The throttle valve 1 can be pivoted into various positions, so that it can allow more or less air to flow through the induction pipe 13. For pivoting the throttle valve 1, a throttle flap adjusting unit 4 is provided that comprises a brushless direct current motor and a gearbox 5 that serve as a drive 3.

(7) In order to keep costs low, the electric motor does not comprise a rotor position detecting device, for example in the form of a dedicated rotor position angle transducer or a current-based angle detection means. In addition, no secondary current regulation is provided.

(8) However, a throttle valve angle transducer 7 is provided, which can measure the position or the disposition angle of the throttle valve 1. As the throttle valve 1 is coupled by means of the gearbox 5 to the electric motor acting as the drive 3, the angle information provided by the throttle valve angle transducer 7 enables an indirect conclusion to be drawn regarding the currently prevailing position of the rotor in the electric motor, so that said information can be used after suitable processing for regulation of the drive 3.

(9) For this purpose initially within the context of a basic adaptation a characteristic is recorded that represents the correlation between the rotor position of the electric motor and an output voltage of the throttle valve angle transducer 7. Using said characteristic, a control unit 11 can then suitably activate the drive 3 of the throttle valve positioning unit.

(10) However, the characteristic can change with time, for example because of temperature influences or wear and tear, and therefore has to be calibrated at certain time intervals.

(11) With reference to FIG. 2, a possible calibration method according to the disclosure is described, such as can be implemented in the control unit 11 for example.

(12) In a first step S1 it is first detected whether the internal combustion engine 9 of the motor vehicle is currently running or is not running. Using the information obtained hereby, it is decided in a step S2 whether a first or a second calibration strategy is to be carried out.

(13) If it is detected that the internal combustion engine 9 is currently running, the characteristic is calibrated (step S5) in a conventional manner. During this, within the context of the calibration process there is no active intervention into the global positioning of the throttle valve 1 because this can influence the operation of the internal combustion engine 9 in an undesirable manner.

(14) Instead the throttle valve 1 is positioned by the control unit 11 according to the current driver demands, which means that the throttle valve 1 is positioned using the throttle valve positioning unit 4 such that the wish of the driver expressed by depressing the gas pedal can be met by the provision of engine power. At the correspondingly adopted positions of the throttle valve, the characteristic can then be currently calibrated, for example with conventional methods such as the pendulum method cited above. This sometimes requires a local displacement of the throttle valve about the target position that is negligibly small within certain limits and is time limited.

(15) If however it is detected that the internal combustion engine 9 is currently not running but is inactive, for example because it has been temporarily stopped by a start-stop system or in the case of a hybrid vehicle temporarily changed to the drive by the auxiliary motor, a different calibration strategy can be carried out. Because the current positioning of the throttle valve 1 is irrelevant when the internal combustion engine 9 is not running, the throttle valve 1 can be displaced into any arbitrary target position. In particular, the current positioning of the throttle valve 1 can be selected independently of current driver demands. In the context of the second calibration strategy, the drive 3 can thus preferably be activated by the controller 11 in a step S3 such that the throttle valve 1 is displaced into a specifiable target position. Then in a step S4 the characteristic is calibrated at said target position. Because when the internal combustion engine 9 is not running the throttle valve 1 can be driven to any arbitrary target position, the characteristic can be calibrated over any arbitrary sub region.

(16) For example, a special correction algorithm can be carried out that specifically corrects the segments of the characteristic that were corrected less frequently or not at all during the preceding operation of the motor vehicle. For example, the throttle valve 1 is typically only slightly open in urban traffic most of the time. Accordingly, only those segments of the characteristic that are associated with a small throttle valve angle are corrected according to the first calibration strategy described above with the internal combustion engine 9 running. In the event of a longer phase with the internal combustion engine not running, for example at a red traffic light, then with the internal combustion engine 9 turned off those segments of the characteristic that correspond to larger throttle valve angles can be corrected. For this, within the context of the second calibration strategy the throttle valve 1 is correspondingly wide open and the characteristic is calibrated by reading out current measurement values from the throttle valve angle transducer 7 and possibly from the electric motor of the drive 3. The characteristic is then already corrected for subsequent long-distance driving, during which the throttle valve 1 is typically wide open.