METHOD FOR DETERMINING THE MASS FLOW IN AN INTERNAL COMBUSTION ENGINE

Abstract

A method for determining mass flow according to the differential pressure method on an internal combustion engine, includes calculating a mass flow signal by using sensors of a mass flow meter to measure a differential pressure, an absolute pressure and a temperature of the mass flow. The mass flow signal is filtered by an evaluation unit of the mass flow meter and the filtered mass flow signal is sent to an engine control. The filter parameters are matched to a measurement situation by the evaluation unit. In a first measurement situation, the filter parameters are set on the basis of an analysis of pulsations of the current measured values and in a second measurement situation, the filter parameters are set on the basis of status data of the internal combustion engine transmitted by the engine control unit. A mass flow meter and a probe are also provided.

Claims

1-7. (canceled)

8. A method for determining a mass flow according to a differential pressure method on an internal combustion engine, the method comprising: calculating a mass flow signal by using sensors of a mass flow meter to measure a differential pressure (dp), an absolute pressure (pabs) and a temperature (temp) of a mass flow; using an evaluation unit of the mass flow meter to filter the mass flow signal by matching filter parameters to measurement situations including a first measurement situation in which the filter parameters are set on a basis of an analysis of pulsations of current measured values and a second measurement situation in which the filter parameters are set on a basis of status data of the internal combustion engine transmitted by an engine control unit; and sending the filtered mass flow signal to the engine control.

9. The method according to claim 8, which further comprises providing at least one of a load state or a rotational speed of the internal combustion engine or a flap position of an exhaust gas recirculation system of the internal combustion engine, as the status data of the internal combustion engine.

10. The method according to claim 8, which further comprises carrying out a change from the first measurement situation to the second measurement situation during a load change of the combustion engine.

11. The method according to claim 8, which further comprises using a filling model of the internal combustion engine to determine the filter parameters in a third measurement situation.

12. The method according to claim 11, which further comprises adapting the filling model to a wear of components of the internal combustion engine.

13. A mass flow meter for carrying out a method according to claim 8 for determining a mass flow in an internal combustion engine, the mass flow meter comprising: sensors for measuring a differential pressure (dp), an absolute pressure (pabs) and a temperature (temp) of a mass flow; an evaluation unit for calculating a mass flow signal; and an interface to a data bus system of an engine control system of the internal combustion engine; the parameters for filtering the mass flow signal containing status data of the internal combustion engine.

14. The mass flow meter according to claim 13, wherein the status data includes at least one of a load state or a rotational speed of the internal combustion engine or a flap position of an exhaust gas recirculation system of the internal combustion engine.

Description

[0010] An essential basic idea of the invention is to propose a method in which the filter parameters of the evaluation unit are matched to a measurement situation, wherein in a first measurement situation the filter parameters are set on the basis of an analysis of pulsations of the current measured values and wherein in a second measurement situation the filter parameters are set on the basis of current status data of the internal combustion engine transmitted by the engine control. A further essential basic idea is to propose a mass flow meter for determining the mass flow in an internal combustion engine, in which the filter parameters of the mass flow signal are determined on the basis of status data of the internal 1 combustion engine which are available in the engine control.

[0011] A such a mass flow meter preferably has a combination of one or more sensors for differential pressure, absolute pressure, temperature, humidity and gas composition and an evaluation unit. The gas composition can alternatively or additionally be calculated by the evaluation unit from a model which determines the EGR rate from a ratio of EGR mass to air mass.

[0012] These basic ideas make it possible to provide a second measurement situation for determining the mass flow, in which an engine-dynamically adaptive filter is used. In the second measurement situation, no filter parameters are determined by the sensor in a self-adaptive manner, but are optimized by a status signal transmitted by the combustion engine, in particular by the engine control of the combustion engine. At the moment of the load or speed change, the sensor can therefore immediately set the filter parameters anew and optimally. This ensures optimal control quality of the measured values in the second measurement situation as well.

[0013] These features enable an intelligent mass flow meter that measures at least the pressure, the temperature and the differential pressure internally and communicates with the engine control unit (ECU) of the internal combustion engine via a data bus, in particular digitally, for example via CAN-BUS. The evaluation unit according to the invention not only sends its measured values to the ECU, but also receives relevant engine characteristics or status data from the ECU, such as engine speed, load, flap position of the EGR or throttle valve. A status signal or status data of the internal combustion engine therefore includes data of the internal combustion engine that relate to its current status. In a particularly preferred embodiment, these signals or data also relate to imminent changes in the state of the internal combustion engine, for example due to control signals currently given to the internal combustion engine, which will result in a change in the state of the engine (e.g. load call by the driver).

[0014] Especially at low speeds of the combustion engine, it is advantageous if the values measured by the sensors are filtered before the mass flow signal is calculated and the result of the mass flow calculation is subjected to further filtering. This makes it possible to generate a stable signal for the control.

[0015] In addition to measuring flows, there is also the possibility of simulating such flows (whether EGR or air) using engine models, so-called filling models. This is difficult for engine control because the engine characteristics change during operation. In particular, the ageing of EGR coolers and also the wear on cylinders and seals cause the filling model to deteriorate noticeably. However, the evaluation unit according to the invention opens up the possibility of integrating a filling model and adapting it continuously. A filling model is particularly interesting where the evaluation unit itself functions poorly, e.g. at low flow rates and high pulsations due to, for example, low speed, high load or an unfavorable signal/noise ratio. Here, the evaluation unit can switch to a load/speed/valve position-based model.

[0016] It is particularly advantageous if the filling model is adapted to the wear of components of the combustion engine. Ideally, for this measurement situation, the evaluation unit can optimize itself on the basis of the data obtained in the favorable load range, such as high speed and high load, and also adapt continuously to the changing engine characteristics due to ageing during operation of the vehicle.