JP4739389B2 - Operation method of internal combustion engine - Google Patents

Description

  The invention relates to a method for operating an internal combustion engine based on the superordinate concept of the independent claims. The object of the present invention is further a computer program, an open-loop control and / or closed-loop control device for an internal combustion engine, and an internal combustion engine based on the superordinate concepts of the dependent claims.

  From the market, automotive internal combustion engines are known in which some of the exhaust gas is fed back into the area of the intake pipe of the internal combustion engine between the throttle valve and the combustion chamber in order to reduce harmful emissions. It has been. This is called exhaust gas recirculation or “AGR (AbGasRuckfuhrung)” for short. In order to further reduce harmful emissions, the exhaust gas fed back may be cooled by the AGR cooler. However, since this can only be expected under very limited operating conditions of the internal combustion engine, it is known to bypass the exhaust gas by a bypass line in other operating conditions. For this purpose, a bypass valve is provided.

  An object of the present invention is to provide an operating method of an internal combustion engine that makes it possible to easily check the function of a bypass valve of an exhaust gas recirculation system and to improve reliability during operation of the internal combustion engine.

  According to the present invention, fluid is directed through the first fluid line at the first position of the bypass valve, and is routed through the second fluid line at the second position of the bypass valve. In the method of operating an internal combustion engine, wherein the flow characteristic of the passage is different from the flow characteristic of the second fluid line, a first parameter representing the flow characteristic of the fluid when the bypass valve is moved to the first position. When the value of is determined and the bypass valve is moved to the second position, the second value of the same parameter is determined and the difference between both determined values is evaluated, from which the function of the bypass valve is determined. Is estimated.

  Other solutions are set forth in the side-by-side claims relating to computer programs, open-loop and / or closed-loop controllers and internal combustion engines. Advantageous extensions of the invention are indicated in the dependent claims. Important Mercumal is further found in the following specification and drawings. In that case, these Mercumal may be important for the present invention, whether in completely different combinations or singly, each not explicitly mentioned.

  With the present invention, the correct functioning of the bypass valve can be checked in a simple manner. Therefore, at any time during operation of the internal combustion engine, information can be obtained as to whether the control of the bypass valve actually results in the desired switching of the fluid flow. A corresponding action can then be taken depending on the confirmed function of the bypass valve. As a result, the operational reliability and operational safety of the internal combustion engine are improved.

  It is particularly advantageous if the method according to the invention is used in an exhaust gas recirculation system (AGR system). In this case, the fluid is exhaust gas that is sometimes fed back to the intake pipe through the exhaust gas recirculation path, in which case the fed back exhaust gas is routed by the first fluid line at the first position of the bypass valve. It is routed through the heat exchanger and is bypassed by the second fluid line at the second position of the bypass valve. With the method according to the invention it is possible to check whether the control of the bypass valve actually results in switching of the exhaust gas flow by passing through the heat exchanger or bypassing the heat exchanger. it can. Although feedback exhaust gas cooling is desirable to reduce harmful emissions under some operating conditions, it is undesirable for the same reason under other operating conditions. Since the correct function of this switching is monitored by the present invention, countermeasures can be taken in a timely manner in the case of malfunction. Therefore, the present invention ultimately helps to reduce or keep the harmful emissions of internal combustion engines at a low level.

  It is particularly advantageous if the parameter describing the flow characteristics of the fluid is characteristic of the flow resistance. In this case, unlike temperature-based monitoring, no additional sensors are required. In addition, the flow resistance is a parameter that changes clearly when the switch is actually made, which facilitates the detection of the switch actually made.

  The parameter indicating the characteristic of the flow resistance can be obtained from the parameter indicating the characteristic of the mass flow passing through the exhaust gas recirculation path and the parameter indicating the characteristic of the pressure difference before and after the exhaust gas recirculation path. Data necessary for this can be obtained relatively easily and accurately, and a reliable evaluation result can be obtained.

  As an extended example, the temperature and pressure in the region between the throttle valve and the combustion chamber of the intake pipe of the internal combustion engine and the number of revolutions of the crankshaft of the internal combustion engine are measured in order to measure parameters indicating the characteristics of mass flow It is proposed that the utilization and this operating method be performed under coasting operation of the internal combustion engine when the throttle valve is closed. The claimed method for the measurement of parameters characterizing the mass flow is generally known as the “pTn method” and is described in detail, for example, in DE 10 2005 004 319 A1. If the pTn method is performed under coasting operation of the internal combustion engine when the throttle valve is closed, the determined mass flow corresponds to an AGR mass flow. Thus, the method according to the invention can be carried out without additional sensors in many internal combustion engines, in which the proposed pTn method gives accurate results.

  For the measurement of the parameters that characterize the pressure difference, the dominant pressure in the exhaust gas pipe can be measured using a sensor. This gives a high accuracy of the method according to the invention.

  However, it is also possible to estimate the dominant pressure in the exhaust gas pipe depending on the atmospheric pressure or the dominant pressure in the region of the particle filter, for the measurement of the parameters that characterize the pressure difference. This is because under the coasting operation when the throttle valve is closed, the mass flow is not sent out through the exhaust gas pipe, and only the AGR mass flow is sent to the internal combustion engine, so that the intake pipe This is based on the idea that feedback is provided in the region between the throttle valve and the intake valve. However, if no mass flow is sent through the exhaust gas pipe, the pressure in the exhaust gas pipe at the branch point of the AGR pipe is approximately equal to the atmospheric pressure or the dominant pressure in the region of the particle filter. Anyway, the pressure can be measured. This extension of the method according to the invention embodies the possibility of abandoning additional sensors, thereby saving costs in the production of internal combustion engines.

  When the difference between the two determined values of the parameter indicative of the fluid flow characteristic is smaller than the limit value, a malfunction of the bypass valve is estimated. This is a simple method using the difference.

  The internal combustion engine of FIG. This internal combustion engine includes a combustion chamber 12, which is connected to an intake pipe 14 on the inlet side and connected to an exhaust pipe 16 on the outlet side.

  An HFM sensor 20 is first disposed in the intake pipe 14 in the direction of flow (arrow 18), and this sensor measures the amount of fresh air drawn through the intake pipe 14. Next, there is a throttle valve 22 in the intake pipe 14, and the amount of fresh air drawn by this valve can be adjusted. There is a supercharger 24 upstream of the throttle valve 22 in the intake pipe 14, which is connected via a mechanical connection 26 to a turbine 28 arranged in the exhaust gas pipe 16. ing.

  The internal combustion engine 10 is provided with an exhaust gas recirculation system 30 having an exhaust gas recirculation path 32, which recirculation path 32 extends from a region 34 between the combustion chamber 12 of the exhaust gas pipe 16 and the turbine 28. It is branched and has an opening in an area between the supercharger 24 of the intake pipe 14 and the combustion chamber 12.

  Looking at the direction of the exhaust gas flow in the exhaust gas recirculation path 32 (arrow 38), an exhaust gas recirculation valve 40 is first arranged in this recirculation path, and the exhaust gas recirculation path 32 is opened and closed by this valve. Can do. A bypass valve 42 is disposed further downstream of the exhaust gas recirculation path 32, and this valve guides the exhaust gas to the first fluid line 44 or the second fluid line 46 depending on the position thereof. The first fluid line 44 has a heat exchanger 48 that cools the exhaust gas flowing through the first fluid line 44. The two fluid pipes 44 and 46 join again at the junction 50. In an embodiment not shown, an exhaust gas recirculation valve is arranged downstream of this heat exchanger.

  The internal combustion engine 10 is also provided with an open-loop control and / or a closed-loop control device in the form of a control device 52, which is programmed to execute a specific method by a computer program. The output side of the open loop control and / or closed loop control device 52 is inter alia connected to the throttle valve 22, the exhaust gas recirculation valve 40 and the bypass valve 42. The open loop control and / or closed loop control device 52 receives signals from the HFM sensor 20 and other sensors on the input side. These sensors include a pressure sensor 54 that measures the pressure p2 in the region 36 of the intake pipe 14 and a temperature sensor 56 that measures the temperature T2 in the region 36 of the intake pipe 14. In an embodiment not shown, the temperature T2 is modeled without being measured. The open loop control and / or the closed loop control device 52 further receives a signal of a rotational speed sensor 58 that measures the rotational speed nmot of the crankshaft (not shown) of the internal combustion engine 10. The internal combustion engine 10 further includes another pressure sensor 60 located in the region 34 of the exhaust gas pipe 16 where it measures the dominant pressure p3.

  During operation, the internal combustion engine controls the throttle valve 22, the exhaust gas recirculation valve 40, and the bypass valve 42 according to the desired operating state of the internal combustion engine 10. In so doing, under certain operating conditions, the bypass valve 42 is controlled so that the exhaust gas fed back flows through the first fluid line 44 and is cooled by the heat exchanger 48 (first position). ). This helps to reduce harmful emissions of the internal combustion engine 10. However, under some operating conditions, such exhaust gas cooling is undesirable. Thus, under such operating conditions, the bypass valve 42 is controlled so that the exhaust gas is fed back through the second fluid line 46 to the region 36 of the intake pipe 14 and is therefore not cooled (first). Second position). Therefore, the correct function of the bypass valve 42 is very important for the exhaust characteristics of the internal combustion engine 10. Therefore, the open loop control and / or the closed loop control device 52 stores a computer program capable of executing a method for checking the function of the bypass valve 42. This method will now be described with reference to FIG.

  After the start at step 62, it is checked at step 64 whether the internal combustion engine is in coasting operation. During the coasting operation, fuel is not injected into the combustion chamber 12, and therefore combustion is not performed. Such coasting operation is seen, for example, when an automobile on which the internal combustion engine 10 is mounted is going downhill. If the answer at step 64 is Y (positive), the throttle valve 22 is closed at step 66, the exhaust gas recirculation valve 40 is opened, and the bypass valve 42 is moved to the first position. Closing the throttle valve 22 means that fresh air is not sent toward the combustion chamber 12 through the intake pipe 14. As a result, the exhaust gas existing in the system is sent from the combustion chamber 12 to the exhaust gas recirculation path 32 through the exhaust gas pipe 16 and is returned to the intake pipe 14 and the combustion chamber 12 again. The exhaust gas is therefore rotated to circulate. In the first position of the bypass valve 42, the first fluid line 44 and the heat exchanger 48 are cooled.

In step 68, the actual pressure p2 and the actual temperature T2 in the region 36 of the intake pipe 14 and the actual rotational speed nmot are measured, and in step 70 the known pTn method (see DE 10 2005 004 319 A1). _{Is used} to calculate the mass flow (dm / dt) _{42_1} flowing through the exhaust gas recirculation path 32. This is possible under coasting operation of the internal combustion engine 10 when the throttle valve 22 is closed, as already mentioned at the beginning. This is because, under this operating condition of the internal combustion engine 10, the exhaust gas present in the system passes from the combustion chamber 12 to the region 34 of the exhaust gas pipe 16, the exhaust gas recirculation path 32, and the region 36 of the intake pipe 14. This is because it is only circulated through the combustion chamber 12 again.

In parallel with this, in step 72, the pressure p2 in the region 36 of the intake pipe 14 and the pressure p3 in the region 34 of the exhaust gas pipe 16 are measured, and from here, in step 74, the bypass valve 42 is in the first position. A pressure difference dp _{42_1} is formed, which shows the characteristics of the pressure difference before and after the exhaust gas recirculation path 32 when being moved to. From the results of step 70 and step 74, in step 76, the flow resistance W _{42_1} is determined, which is therefore moved by the bypass valve 42 to the first position and thereby the exhaust gas through the heat exchanger 48. It means the total flow resistance of the exhaust gas recirculation path 32 when flowing.

In step 78, a signal is sent from the open loop control and / or closed loop controller 52 to the bypass valve 42 to move the valve to the second position. Next, at step 80, the actual pressure p2 and the actual temperature T2 in the region 36 of the intake pipe 14 and the actual rotational speed nmot of the crankshaft of the internal combustion engine 10 are again measured, and from here it is again known at step 82. The mass flow (dm / dt) _{42_2} flowing through the exhaust gas recirculation path 32 when the bypass valve 42 is moved to the second position is calculated using the pTn method. In parallel with this, in step 84, the actual pressure p3 in the region 34 of the exhaust gas pipe 16 and the pressure p2 in the region 36 of the intake pipe 14 are measured, and from this, in step 86, the pressure difference dp _{42_2} is determined. From the results in step 82 and step 86, in step 88, the flow resistance W _{42_2} is determined. Thus, this flow resistance is such that the bypass valve 42 is closed (assuming that the bypass valve is functioning correctly) and the exhaust gas is diverted through the second fluid line 46 to the heat exchanger 48. This means the flow resistance before and after the exhaust gas recirculation path 32.

  In step 90, the difference between the two flow resistances determined in steps 76 and 88 is made and compared to a predetermined limit value. If the difference is less than the limit value, then at step 92, malfunction of the bypass valve 42 is estimated. Thereafter, the program ends at step 94. If it is determined in step 90 that the flow resistance difference is greater than the limit value, then in step 96 the correct function of the bypass valve 42 is estimated. This estimate is that the flow resistance of the first fluid line 44 is the same as the flow resistance of the second fluid line 46 because the heat exchanger 48 disposed in the first fluid line 44 obstructs the flow. Is based on the idea that they must be different. Therefore, it can also be said that the flow characteristics of the first fluid line 44 are different from the flow characteristics of the second fluid line 46 because of the heat exchanger 48 present therein. Therefore, if it is confirmed that the flow resistance through the exhaust gas recirculation path 32 has not changed after the switching control command for the bypass valve 42, the malfunction of the bypass valve 42 can be estimated.

  In the embodiment described above, the pressure p3 was measured by the pressure sensor 60. However, with the use of such a pressure sensor, instead of a soot particle filter 98 located downstream of the turbine 28 in the exhaust gas pipe 16, which is instead provided in many internal combustion engines anyway. It is also possible to use a pressure sensor in the region. Such a sensor is indicated in FIG. 1 by a broken line and indicated by reference numeral 60 '. Similarly, a sensor located upstream of the HFM sensor 20 can also be used for measuring the pressure p2 and temperature T2 in the region 36 of the intake pipe 14, and then the corresponding value can be estimated. . These sensors are also indicated by broken lines in FIG. 1 and are indicated by reference numerals 54 'and 56'.

FIG. 1 is a schematic view of an internal combustion engine with exhaust gas recirculation. FIG. 2 is a flow diagram of a method for operation of the internal combustion engine of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine 12 ... Combustion chamber 14 ... Intake pipe 16 ... Exhaust gas pipe 18 ... Arrow 20 which shows the direction of the flow in an intake pipe ... HFM sensor 22 ... Throttle valve 24 ... Supercharger 26 ... Mechanical connection 28 ... Turbine 30 ... exhaust gas recirculation system 32 ... exhaust gas recirculation path 34 ... area 36 between the combustion chamber of the exhaust pipe and the turbine ... area 38 between the throttle valve and the combustion chamber of the intake pipe ... direction 40 of the flow of the exhaust gas ... Exhaust gas recirculation valve 42 ... Bypass valve 44 ... First fluid line 46 ... Second fluid line 48 ... Heat exchanger 50 ... Junction 52 of first and second fluid lines ... Open loop control and / or Or closed loop controller 54 ... pressure sensor 54 '... other sensor 56 ... temperature sensor 56' ... other temperature sensor 58 ... rotational speed sensor 60 ... other pressure sensor 60 '... pressure sensor 98 in the area of the soot particle filter ... grain Filter step 62 ... Start step 64 ... Check whether the internal combustion engine is coasting or not 66: Close the throttle valve, open the exhaust gas recirculation valve, and move the bypass valve to the first position 68 Step 70 for measuring the actual pressure and temperature in the intake pipe region 36 and the actual number of revolutions nmot ... Step 72 for calculating the mass flow through the exhaust gas recirculation path using the known pTn method ... Step 74 for measuring the pressure p2 in the intake pipe region 36 and the pressure p3 in the region 34 of the exhaust gas pipe ... Step 76 for forming the pressure difference dp _{42_1} ... Step 78 for determining the flow resistance W _{42_1} ... From the controller 52 A signal is sent to the bypass valve 42 to move it to the second position 80... Actual pressure in the intake pipe region 36 Step 82 for measuring force, actual temperature, and actual rotational speed nmot ... Mass flow (dm / dt) _{42_2} flowing through the exhaust gas recirculation path when the bypass valve 42 is moved to the second position _{42_2} Step 84: The actual pressure p3 in the region 34 of the exhaust gas pipe and the pressure p2 in the region 36 of the intake pipe 14 are measured 86: The pressure difference dp _{42_2} is obtained 88: The flow resistance W _{42_2} is determined Step 90 ... The difference between the two flow resistances is made and compared with a limit value 92. If the difference is less than the limit value, a bypass valve malfunction is estimated 94 ... The program ends Step 96 ... If the difference is greater than the limit value, the correct function of the bypass valve is estimated

Claims (8)

Fluid is directed through the first fluid line (44) at the first position of the bypass valve (42) and through the second fluid line (46) at the second position of the bypass valve (42). In the operating method of the internal combustion engine (10), the flow characteristics of the first fluid line (44) are different from the flow characteristics of the second fluid line (46).
The parameters are characteristic of flow resistance;
The fluid is exhaust gas that is sometimes fed back to the intake pipe (14) through the exhaust gas recirculation path (32), and this fed back exhaust gas is the first fluid in the first position of the bypass valve (42). Led through a heat exchanger (48) by a conduit (44) and bypassed through the heat exchanger by a second fluid conduit (46) in a second position of the bypass valve (42);
The parameters indicating the characteristics of the flow resistance indicate the parameters indicating the characteristics of the mass flow flowing through the exhaust gas recirculation path (32) and the characteristics of the pressure difference before and after the exhaust gas recirculation path (32). What is required from the parameters,
When a bypass valve (42) is moved to a first position, a first value of a parameter indicative of the flow resistance characteristic is determined ;
When the bypass valve (42) is moved to the second position, a second value of the parameter indicative of the flow resistance characteristic is determined, and the difference between both determined values is evaluated. The function of the bypass valve is estimated from this,
An operating method of an internal combustion engine characterized by the above. In order to measure the parameters characteristic of the mass flow, the temperature in the region (T) between the throttle valve (24) and the combustion chamber (12) of the intake pipe (14) of the internal combustion engine (10) (T ₂ ) and pressure (p ₂ ), and the number of revolutions of the crankshaft of the internal combustion engine (10), and this operating method is used when the throttle valve (24) is closed. To be performed during coasting operations,
The driving method according to claim 1 , wherein: The dominant pressure (p ₃ ) in the exhaust gas pipe (16) is measured using a sensor (60) to measure a parameter indicative of the pressure difference characteristic. Item 3. The operation method according to Item 1 or 2 . In order to measure the parameters characteristic of the pressure difference, the dominant pressure (p3) in the exhaust gas pipe (16) is reduced to the dominant pressure in the region of atmospheric pressure or particle filter (98). the method of operation according to claim 1 or 2, characterized in that the estimated dependent. When the difference between the two values obtained with parameters that indicate the characteristics of the flow resistance is smaller than the limit value, the bypass valve of claims 1 to 4 malfunction is characterized in that it is estimated (42) The driving | operation method in any one. Computer program, characterized in that it is programmed for use in operating the method according to any one of claims 1 to 5. Open-loop control and / or closed-loop control unit for, characterized in that it is programmed for use in operating the method according to any one of claims 1 to 5, the internal combustion engine (10) (52). Internal combustion engine for a motor vehicle, characterized in that it comprises an open-loop control has been programmed and / or closed-loop control unit (52) for use in the operation method according to any one of claims 1 to 5 (10 ).

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