Operation Of An Internal Combustion Engine Having A Wastegate Turbocharger

Abstract

Various embodiments may include a method for operating an internal combustion engine having a wastegate turbocharger comprising: measuring an intake pipe pressure; determining a cylinder air mass from the pressure; injecting an amount of fuel into a cylinder of the internal combustion engine based on the air mass; determining and a plausible intake pipe pressure gradient for a current engine operating point; calculating a gradient of the measured intake pipe pressure during a full-load acceleration; comparing the stored plausible intake pipe pressure gradient to the calculated gradient; identifying manipulation of the intake pipe pressure sensor if the difference between the stored plausible intake pipe pressure gradient and the calculated gradient exceeds a selected threshold value; and limiting a power output of the engine if manipulation is identified.

Claims

1. A method for operating an internal combustion engine having a wastegate turbocharger, the method comprising: measuring an intake pipe pressure; determining a cylinder air mass based at least in part on the measured intake pipe pressure; injecting an amount of fuel into a cylinder of the internal combustion engine based on the determined cylinder air mass; determining and storing a plausible intake pipe pressure gradient for a current engine operating point; calculating a gradient of the measured intake pipe pressure during a full load acceleration; comparing the stored plausible intake pipe pressure gradient to the calculated gradient; identifying manipulation of the intake pipe pressure sensor if the difference between the stored plausible intake pipe pressure gradient and the calculated gradient exceeds a selected threshold value; and limiting a power output of the internal combustion engine if manipulation is identified.

2. The method as claimed in claim 1, wherein an identified manipulation is stored in an error memory of an engine control device associated with the internal combustion engine.

3. (canceled)

4. The method as claimed in claim 1, further comprising calculating a gradient of the current intake pipe pressure during each full-load acceleration of the internal combustion engine.

5. The method as claimed in claim 1, wherein the plausible intake pipe pressure gradient is determined on an unmanipulated reference engine.

6. The method as claimed in claim 1, wherein the engine operating point is characterized by an engine speed and/or gear ratio.

7. An internal combustion engine comprising: a wastegate turbocharger; a combustion cylinder; and an engine control device with a processor programmed to: measure an intake pipe pressure; determine a cylinder air mass based at least in part on the measured intake pipe pressure; inject an amount of fuel into a cylinder of the internal combustion engine based on the determined cylinder air mass; determine and storing a plausible intake pipe pressure gradient for a current engine operating point; calculate a gradient of the measured intake pipe pressure during a full-load acceleration; compare the stored plausible intake pipe pressure gradient to the calculated gradient; identify manipulation of the intake pipe pressure sensor if the difference between the stored plausible intake pipe pressure gradient and the calculated gradient exceeds a selected threshold value; and limit a power output of the internal combustion engine if manipulation is identified.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The teachings herein are explained in detail below with reference to an exemplary embodiment in connection with the drawing. The single figure shows a flow diagram of a method incorporating the teachings of the present disclosure.

DETAILED DESCRIPTION

[0021] To enable a manipulation of the measured value of the intake pipe pressure at a specific engine operating point to bring about an increase in the actual power of the internal combustion engine in the manner described above, the engine should be capable at this operating point of actually increasing the air mass flow into the engine beyond the air mass flow demanded by the engine controller for this engine operating point by adjusting the actuators of the air path. For internal combustion engines having a wastegate turbocharger, the relevant actuators in the air path for controlling the air mass flow include the throttle valve for controlled throttling and the wastegate for controlling the turbocharger power. At engine operating points in the boost mode close to full load, the throttle valve is generally fully open and does not offer any possibility of further increasing the air mass flow. Therefore, it is only possible to achieve an increase in the air mass flow at engine operating points close to full load by increasing the turbocharger power by means of further closure of the wastegate.

[0022] Conversely, this means that, at engine operating points with an open throttle valve and a closed wastegate, it is not possible to actually increase the air mass flow and hence the engine power by manipulating the measured values. There are no known tuning devices which are capable of evaluating the wastegate actuating signals transmitted by the engine control device and/or of evaluating the position feedback of the wastegate to the engine control device. Therefore, any manipulation of the measured value of the intake pipe pressure acts both at engine operating points with a partially open waste gate and at engine operating points with a fully closed wastegate. This gives rise to the possibility, at operating points with a closed wastegate, of comparing the engine state variables modeled in the engine controller on the basis of the currently measured intake pipe pressure with values for this state variable which are stored in the engine control device and are plausible for this operating point.

[0023] In a steady state with constant state variables, especially with a constant engine speed, engines in actual road conditions are very seldom operated with a closed wastegate. This occurs only at a low engine speed when hill climbing. At all other operating points, the engine power is sufficient to accelerate the engine. These operating points are therefore not steady. However, operating points with a closed wastegate often occur for a few seconds during full-load acceleration phases. During a full-load acceleration, the air mass flow and hence the pressure ahead of the throttle valve, the intake pipe pressure, the engine power and the engine speed increase with the maximum possible gradient for the respective engine operating point for several seconds owing to the full opening of the throttle valve and the full closure of the wastegate. This operating-point-specific maximum gradient of the intake pipe pressure is stored in the engine control device.

[0024] During a full-load acceleration, the gradient of the intake pipe pressure is calculated in the engine control device on the basis of the measured intake pipe pressure. If the measured value of the intake pipe pressure is being manipulated toward lower values by a tuning device, the gradient calculated from the manipulated measured values is lower than the plausible gradient stored for the current engine operating point in the engine control device. If the difference between the stored plausible intake pipe gradient and the currently calculated intake pipe pressure gradient exceeds a selected threshold value, manipulation of the intake pipe pressure sensor is detected.

[0025] In this case, the detected manipulation may be stored in the error memory of the engine control device. As an error response, the power of the engine can be limited, for example.

[0026] In some embodiments, the gradient of the current intake pipe pressure may be calculated during each full-load acceleration. In particular, the plausible intake pipe pressure gradient stored in the engine control device may be determined on an un-manipulated reference engine.

[0027] In some embodiments, the engine operating point may be characterized by the engine speed and/or gear ratio, in particular also by the intake pipe pressure at the beginning of the full-load acceleration and/or by the gradient of the engine speed.

[0028] In some embodiments, an internal combustion engine having a wastegate turbocharger and an engine control device is designed for carrying out the above-described method.

[0029] In some embodiments, manipulation of the intake pipe sensor and an increase thereby achieved in the power of an internal combustion engine having a wastegate turbocharger can be detected. The example embodiment described below relates to an internal combustion engine which has a wastegate turbocharger. A wastegate is a flap which guides the exhaust gases in the turbocharger past the turbine wheel. Furthermore, the internal combustion engine has an intake pipe pressure sensor, which measures the intake pipe pressure. From this, an engine control device determines the cylinder air mass. Based on the cylinder air mass determined, a corresponding fuel quantity is injected.

[0030] There are known tuning measures for internal combustion engines of this kind in which a real increase in the intake pipe pressure relative to the measured value of the intake pipe pressure is achieved by manipulating the measured intake pipe pressure toward lower values by installing a tuning device between the intake pipe pressure sensor and the engine control device to manipulate the sensor signals accordingly. In the method described, it is now a question of detecting manipulation of the intake pipe pressure sensor.

[0031] In a first step, a plausible intake pipe pressure gradient for a respectively current engine operating point is determined and stored in the engine control device. This plausible intake pipe pressure gradient is determined on an un-manipulated reference engine (step 1).

[0032] In step 2, the gradient of the current intake pressure measured with the intake pipe pressure sensor during a full-load acceleration is calculated by the engine control device.

[0033] In step 3, the two values are compared with one another, and, in step 4, if the difference between the stored plausible intake pipe pressure gradient and the currently calculated intake pipe pressure gradient exceeds a selected threshold value, manipulation of the intake pipe pressure sensor is detected.

[0034] The detected manipulation can then be stored in the error memory of the engine control device (step 5), and the power of the internal combustion engine can be limited as an error response as a targeted countermeasure (step 6).