EGR Effective Flow Diagnostic Procedure

Abstract

Exhaust gas recirculation (EGR) effective flow diagnostic procedure, the procedure comprising the following: Measuring an EGR gas temperature (S15) by an EGR gas temperature sensor under an EGR gas temperature rise condition in an EGR system at an intake manifold; Determining the degree of EGR gas temperature rise by a processor; and determining whether an EGR effective flow rate is excessive or insufficient, depending on the degree of EGR gas temperature rise by the processor. which includes determining the degree of the EGR gas temperature increase: Calculating the EGR effective flow rate through the processor according to the degree of the EGR gas temperature increase (S16); Calculating a relationship between the EGR effective flow rate and an EGR valve position by the processor (S17); and Calculating the EGR effective flow rate at a 0% position of the EGR valve (S21) and an EGR effective flow rate at a 100% position of the EGR valve (S22) from the relationship between the EGR effective flow rate and the EGR valve position.

Description

BACKGROUND OF REVELATION Area of ​​Revelation

[0001] The present invention relates to a method for diagnosing the presence or absence of an effective flow by opening and closing the exhaust gas recirculation (EGR). Description of the related technique

[0002] Exhaust gas recirculation (EGR) was recently developed and implemented to improve the fuel efficiency of a vehicle engine.

[0003] US Patent 6,446,498 B1 discloses a method for determining the condition of an EGR system for an internal combustion engine. It states that the EGR valve is moved to two different positions, a temperature is measured in the EGR system in each position, and the condition of the EGR system is determined from the difference in temperature. Measurements are taken first with the EGR valve closed and then with it open. In the simplest case, the EGR system is considered to be functioning correctly if a temperature increase is observed when switching from the closed to the open EGR valve; that is, a distinction is made between "sufficient flow" and "insufficient flow."

[0004] Publication US 2014 / 0 372 010 A1 discloses a method for diagnosing an EGR system.

[0005] Document DE 41 21 071 A1 discloses an exhaust gas recirculation system for an internal combustion engine.

[0006] An EGR system refers to a method for reducing nitrogen oxides (NOx) in exhaust gas and refers to a device or system for recirculating a portion of the inert exhaust gas into an intake system. An EGR system mixes the inert exhaust gas into the intake gases drawn into the engine to lower the peak combustion temperature and thus reduce NOx emissions.

[0007] To ensure functionality, the EGR system also monitors the intake temperature, coolant temperature, vehicle speed, or gear position to control a portion of the exhaust gas and return it to an intake manifold under the most appropriate control depending on the operating conditions.

[0008] In other words, as in Fig. As shown in Figure 1, the EGR system is configured to capture exhaust gas expelled from a cylinder at the rear end of a catalytic converter and direct it to the front end of a compressor. The EGR system controls whether the exhaust gas is recirculated through an EGR valve on an EGR channel.

[0009] In this example, to determine whether the EGR system is functioning normally, it is necessary to diagnose whether there is an effective EGR flow when the EGR valve is closed (opening diagnosis) or whether there is no effective EGR flow when the EGR valve is open (blockage diagnosis).

[0010] The diagnosis of an EGR system blockage or complete opening was usually made by determining the EGR effective flow rate (kg / h) as the difference between the effective flow rate (kg / h) calculated by a manifold absolute pressure sensor (MAP sensor) and the effective flow rate (kg / h) calculated by a mass airflow sensor (MAF sensor). A MAP sensor is located between a cylinder and a throttle valve. The MAF sensor is located at the front end of the compressor. The EGR effective flow rate is compared to a model of the effective flow rate calculated by an EGR valve model to determine whether the EGR effective flow rate is insufficient or excessive.

[0011] However, such a method is impractical in real-world applications, as it will result in a finding that nothing is present, even when the EGR effective flow rate is present, or vice versa. This is because there is a significant discrepancy between the effective flow rate calculated by the MAP sensor and the effective flow rate calculated by the MAF sensor.

[0012] The content described in the section “Description of the related technology” is intended to contribute to an understanding of the background of the present revelation and may also include things that were previously unknown to a person with ordinary knowledge of the technology to which the present revelation relates. SUMMARY OF THE REVELATION

[0013] The present disclosure is intended to solve the problem described above. One objective of the present disclosure is to provide an exhaust gas recirculation (EGR) effective flow diagnostic method capable of performing an accurate opening diagnosis or a blockage diagnosis, even if an EGR valve or cooler is abnormal.

[0014] An EGR effective flow diagnostic method according to the invention is specified in claim 1.

[0015] Furthermore, measuring the EGR gas temperature can include measuring in a state where the EGR valve is closed or in a state where it is open. Measuring the EGR gas temperature can also include determining, before or after calculating the ratio between the effective EGR flow rate and the EGR valve position, whether the measurement, taken with the EGR valve closed, exceeded a closed reference number and, with the EGR valve open, whether it exceeded an open reference number.

[0016] Furthermore, if the measurement by measuring the EGR gas temperature in the state where the EGR valve is closed does not exceed the closed reference number, or in the state where the EGR valve is open does not exceed the open reference number, the EGR differential pressure can be checked.

[0017] In this example, the measurement of the EGR gas temperature can be repeated each time the EGR valve position is changed.

[0018] The EGR effective flow diagnostic procedure can further include confirming whether the EGR effective flow in the 100% position of the EGR valve is below a no-flow threshold. If the EGR effective flow in the 100% position of the EGR valve is less than the no-flow threshold, the EGR effective flow is diagnosed as an EGR blockage.

[0019] Alternatively, the EGR effective flow diagnostic procedure can also include confirming whether the EGR effective flow in the 0% position of the EGR valve exceeds a maximum flow limit. If the EGR effective flow in the 0% position of the EGR valve exceeds the maximum flow limit, the EGR effective flow is diagnosed as EGR opening.

[0020] Furthermore, after measuring the EGR gas temperature, the degree of the EGR gas temperature increase can be normalized to the exhaust energy.

[0021] An EGR effective flow diagnostic procedure according to another aspect of the present disclosure includes: checking whether the exhaust pressure of an exhaust gas is increasing; measuring an EGR gas temperature by an EGR gas temperature sensor when the exhaust pressure increase exceeds a predetermined reference value.

[0022] Furthermore, measuring the EGR gas temperature in a state where an EGR valve is closed or in a state where it was open, and after calculating the relationship between the EGR effective flow rate and the EGR valve position, may include determining whether the measurement by measuring the EGR gas temperature exceeded a closed reference number in a state where the EGR valve was closed and an open reference number in a state where the EGR valve was open.

[0023] Furthermore, the EGR differential pressure can be checked if the measurement by measuring the EGR gas temperature in the state where the EGR valve is closed does not exceed the closed reference number, or in the state where the EGR valve is open does not exceed the open reference number.

[0024] The EGR effective flow diagnostic procedure can further include confirming whether the EGR effective flow at the 100% position of the EGR valve is less than a no-flow threshold. If the EGR effective flow at the 100% position of the EGR valve is less than the no-flow threshold, the EGR effective flow is diagnosed as an EGR blockage.

[0025] Furthermore, the EGR effective flow diagnostic procedure can also include confirming whether the EGR effective flow in the 0% position of the EGR valve exceeds a maximum flow limit. If the EGR effective flow in the 0% position of the EGR valve exceeds the maximum flow limit, the EGR effective flow is diagnosed as EGR opening.

[0026] An EGR effective flow diagnostic procedure according to yet another aspect of the present disclosure comprises: checking whether the engine load is increasing; measuring an EGR gas temperature by an EGR gas temperature sensor when the engine load exceeds a predetermined reference value.

[0027] Furthermore, measuring the EGR gas temperature can include measurements taken with the EGR valve closed or open. After calculating the ratio between the effective EGR flow rate and the EGR valve position, measuring the EGR gas temperature can further include determining whether the measurement with the EGR valve closed exceeded a closed reference number and whether the measurement with the EGR valve open exceeded an open reference number.

[0028] If the measurement by measuring the EGR gas temperature does not exceed the closed reference number in the state where the EGR valve is closed, or the open reference number in the state where the EGR valve is open, the EGR differential pressure can be checked.

[0029] The EGR effective flow diagnostic procedure can further include confirming whether the EGR effective flow at the 100% position of the EGR valve is below a no-flow threshold. If the EGR effective flow at the 100% position of the EGR valve is less than the no-flow threshold, the EGR effective flow is diagnosed as an EGR blockage.

[0030] Alternatively, the EGR effective flow diagnostic procedure also includes confirming whether the EGR effective flow in the 0% position of the EGR valve exceeds a maximum flow limit. If the EGR effective flow in the 0% position of the EGR valve exceeds the maximum flow limit, the EGR effective flow is diagnosed as EGR opening.

[0031] If the EGR valve, cooler, or similar component is clogged, the EGR gas will not flow, even if the EGR valve is open. Since the temperature of the EGR gas will not rise, or will rise only slowly, at this point, it can be seen that the EGR system is clogged by the aforementioned issue.

[0032] If the EGR valve, cooler, or similar component is structurally open, a large amount of EGR gas can flow even if the EGR valve should be closed. Since the EGR valve remains in a state where the temperature of the EGR gas has increased, it can be seen that the EGR valve is open due to the points mentioned above.

[0033] As described above, it is possible to make an accurate diagnosis of EGR blockage / opening based on the amount and rate of change of the EGR gas temperature measured by the EGR gas temperature sensor.

[0034] Therefore, there is no possibility of misdiagnosis due to errors in the MAF and MAP sensors.

[0035] Therefore, it is possible to improve the accuracy of the diagnosis of the effective flow rate of the EGR, thereby maintaining the effect of fuel consumption improvement through the EGR system. BRIEF DESCRIPTION OF THE FIGURES Fig. Figure 1 is a diagram illustrating a conventional exhaust gas recirculation (EGR) system. Fig. Figure 2 is a diagram illustrating an EGR system to which the present disclosure is applied. Fig. Figure 3 is a diagram illustrating a condition in which an EGR valve is in the Fig. The system shown in section 2 is blocked. Fig. 4 is a diagram illustrating a state in which the EGR valve is in the Fig. The system shown in section 2 was opened. Fig. Figure 5 is a diagram illustrating the relationship between EGR valve position and EGR effective flow rate under normal / abnormal conditions. Fig. 6A and Fig. 6B are diagrams that illustrate the relationship between the EGR valve position and the EGR effective flow rate by checking an EGR gas temperature. Fig. Figure 7 is a flowchart that sequentially illustrates an EGR effective flow diagnostic procedure according to the present disclosure. DESCRIPTION OF THE SPECIFIC VERSIONS

[0036] In order to fully understand the present disclosure, the operational advantages of the present disclosure and the objectives achieved through the practice of the present disclosure, reference should be made to the accompanying drawings, which illustrate various embodiments of the present disclosure and the contents described in the accompanying figures.

[0037] In describing the embodiments of the present disclosure, known techniques or repeated descriptions that might unnecessarily obscure the subject matter of the present disclosure are abbreviated or omitted.

[0038] Fig. Figure 2 is a diagram illustrating an exhaust gas recirculation (EGR) system to which the present disclosure is applied. Fig. Figure 3 is a diagram illustrating a condition in which an EGR valve is in the Fig. The system shown in section 2 is blocked. Fig. 4 is a diagram illustrating a state in which the EGR valve is in the Fig. The system shown in section 2 was opened.

[0039] An EGR effective flow diagnostic procedure according to the present disclosure is configured to prevent an EGR effective flow from being incorrectly identified due to a fault in an EGR system, such as an EGR valve or a cooler.

[0040] If the EGR valve, the cooler, or similar components are clogged, as in Fig. As shown in Figure 3, the EGR gas does not flow even when the EGR valve is open. Since the temperature of the EGR gas does not rise or rises only slowly, it is possible at this point to determine whether the EGR is blocked, depending on whether the temperature of the EGR gas has increased.

[0041] If the EGR valve, cooler, or similar component is structurally open, as in Fig. As shown in Figure 4, a large amount of EGR gas flows even when the EGR valve should be closed. At this point, the gas remains in a state where the EGR gas temperature has increased. Therefore, it is possible to determine whether the EGR valve was open based on whether the EGR gas temperature has increased.

[0042] In other words, the present disclosure can diagnose EGR blockage / opening based on the amount and rate of change of the EGR gas temperature as measured by the EGR gas temperature sensor.

[0043] With reference to Fig. 5. With a normal EGR valve, the effective EGR flow rate is generally proportional to the position of the EGR valve.

[0044] However, if the EGR valve is clogged, the effective EGR flow remains low and does not change even if the EGR valve position is changed.

[0045] However, if a leak or similar occurs in the EGR valve, the effective EGR flow rate remains high and does not change even if the position of the EGR valve changes.

[0046] The following Fig. 6A and Fig. Figure 6B shows diagrams illustrating the relationship between the EGR valve and the EGR effective flow rate through the EGR gas temperature control.

[0047] Although described below, the EGR method described in this disclosure calculates the effective EGR flow rate using the degree of EGR gas temperature rise, performs the calculation repeatedly to derive their relationship as a regression line, and compares the effective EGR flow rate when the EGR valve is in a closed position and the effective EGR flow rate when the EGR valve is in an open position to a reference value using the regression line. In this way, the blockage or opening of the EGR valve can be diagnosed.

[0048] When checking the EGR effective flow rate as a function of the EGR gas temperature by a predetermined number of times as in Fig. As shown in Figure 6A, a meaningful regression line can therefore be derived. If the number of EGR effective flow checks, as shown in Fig. If the information shown in 6B is insufficient, it is not possible to derive the regression line.

[0049] Fig. Figure 7 is a flowchart that sequentially illustrates an EGR effective flow diagnostic procedure according to the present disclosure. The EGR effective flow diagnostic procedure according to the present disclosure is described below with reference to Fig. 7 described in more detail.

[0050] First, an EGR gas temperature is checked (S11) when the EGR valve is closed. This process determines whether the number of EGR gas temperature checks has exceeded a closed reference number (N_CLOSED).

[0051] Therefore, if the number of EGR gas temperature checks has exceeded the closed reference number, the EGR valve is closed (S12), and if it has not exceeded the closed reference number, the EGR valve is open (S13).

[0052] After S12 and S13 are controlled, the EGR differential pressure is checked (S14) to determine whether it has exceeded a reference differential pressure. The differential pressure is measured by a differential pressure sensor located on an intake manifold of the engine.

[0053] The method described in this disclosure diagnoses the blockage / opening of the EGR system depending on the degree of the EGR gas temperature increase. Exceeding the reference differential pressure of the EGR differential pressure corresponds to a control input state, which is a state in which the EGR gas temperature increase is expected.

[0054] In addition to the above, the tax input condition of the present disclosure can be determined by an accelerated vehicle or by an increased engine load.

[0055] As a result of step S14, if the EGR differential pressure exceeds the reference differential pressure, the EGR gas temperature is measured (S15) to calculate the degree of the EGR gas temperature increase. The EGR gas temperature is measured using the EGR gas temperature sensor.

[0056] The degree of EGR gas temperature increase is then normalized to the exhaust gas energy to eliminate external effects other than the EGR effective flow rate.

[0057] In other words, the degree of temperature increase is divided by the differential pressure increase, or the degree of temperature increase is corrected to a value corresponding to the exhaust energy, thus eliminating the engine temperature increase, the coolant temperature increase, or the engine compartment temperature increase.

[0058] Next, after measuring the EGR gas temperature (S15), the effective EGR flow rate is calculated according to the EGR gas temperature increase (S16) and the relationship between the EGR effective flow rate and the EGR valve position is calculated (S17).

[0059] This process is repeated several times by checking (S18) each time the EGR valve opens and closes whether the number of EGR gas temperature checks has been exceeded. Steps S14–S17 are repeated until the specified number of times is exceeded.

[0060] In other words, step S18 determines whether the number of EGR gas temperature checks has exceeded the closed reference number (N_CLOSED) in a closed state, and whether the number of EGR gas temperature checks has exceeded an open reference number (N_OPEN) in a closed state. If the number of EGR gas temperature checks has not exceeded the reference numbers N_CLOSED and N_OPEN, the position of the EGR valve is changed so that the EGR gas temperature is measured multiple times in S15.

[0061] Therefore, in this example, the relationship between the EGR effective flow rate and the EGR valve position calculated according to the EGR gas temperature is calculated, and the result can be represented by a regression line as in Fig. 6A will be shown.

[0062] Therefore, if the number of EGR gas temperature measurements exceeds the closed reference number and the open reference number in step S18, an effective EGR flow rate at the 0% position of the EGR valve (S21) and an effective EGR flow rate at the 100% position of the EGR valve (S22) are calculated successively using the relationship between effective EGR flow rate and EGR valve position derived in step S17 (which is shown in Fig. 6A (regression line shown). In this example, the order of the calculations in steps S21 and S22 is irrelevant.

[0063] Based on the calculation result from step S22, it is confirmed whether the effective EGR flow at the 100% position of the EGR valve is less than a no-flow threshold (S23). In this case, the EGR flow is not detectable and an EGR blockage is diagnosed (S24).

[0064] Furthermore, the calculation result from step S21 is used to confirm whether the EGR effective flow rate in the 0% position of the EGR valve exceeds a maximum flow limit (S25). If so, the maximum EGR flow rate is detected and an EGR opening (S26) is diagnosed. Otherwise, a passage is reported (S27) if the EGR effective flow rate in the 0% position of the EGR valve does not exceed the maximum flow limit.

[0065] As described above, in contrast to the conventional method according to the present disclosure, the EGR effective flow diagnostic method can diagnose the EGR system more accurately by determining the blockage anomaly or the opening anomaly of the EGR valve by the degree of the EGR gas temperature increase.

[0066] In one embodiment, the EGR system may include an electronic control unit (ECU). The ECU may be or include a microprocessor or other computer hardware device that can be programmed with software, firmware, or otherwise. The ECU meets the standard specifications for use and operation in vehicles.

[0067] The control unit can be an application-specific integrated circuit (ASIC), a digital signal processor, a field-programmable gate array (FPGA), a digital circuit, an analog circuit, a general-purpose processor, or a combination thereof. In one example, the processor is one or more processors used to control and / or communicate with the various electronics and logic of the associated components or devices.

[0068] The control unit can execute an EGR (Effective Flow) diagnostic program, which contains computer-executable instructions implemented in software or firmware. The control unit can execute the program commands to perform the functions of the EGR system, as explained here.

[0069] Although the present disclosure described above has been described with reference to the figures, it is not limited to the embodiments described. It should be obvious to a person with ordinary technical knowledge that various changes and modifications can be made without departing from the spirit and scope of the present disclosure. Therefore, such amended or modified examples may be included in the claims of the present disclosure, and the scope of the present disclosure should be interpreted on the basis of the appended claims.

Claims

[1] Exhaust gas recirculation (EGR) effective flow diagnostic method, the method comprising: Measuring an EGR gas temperature (S15) by an EGR gas temperature sensor under an EGR gas temperature rise condition in an EGR system at an intake manifold; Determining the degree of EGR gas temperature rise by a processor; and determining whether an EGR effective flow rate is excessive or insufficient, depending on the degree of EGR gas temperature rise by the processor. which includes determining the degree of the EGR gas temperature increase: Calculating the EGR effective flow rate through the processor according to the degree of the EGR gas temperature increase (S16); Calculating a relationship between the EGR effective flow rate and an EGR valve position by the processor (S17); and Calculating the EGR effective flow rate at a 0% position of the EGR valve (S21) and an EGR effective flow rate at a 100% position of the EGR valve (S22) from the relationship between the EGR effective flow rate and the EGR valve position. [2] Method according to claim 1, wherein measuring the EGR gas temperature (S15) includes measuring the EGR gas temperature when an EGR valve of the EGR system is closed or when the EGR valve was open. [3] Method according to claim 1, wherein it is determined before or after measuring the EGR gas temperature (S15) whether a gas temperature measurement reference is to be met. [4] Method according to claim 3, wherein determining whether the gas temperature measurement reference is met includes determining whether the measurement by measuring the EGR gas temperature (S15) exceeded a closed reference number in a state in which the EGR valve was closed, and / or whether the measurement exceeded an open reference number in a state in which the EGR valve was open. [5] Method according to claim 1, wherein the measurement of the EGR gas temperature (S15) is performed repeatedly each time the EGR valve position is changed. [6] Method according to claim 1, further comprising confirming whether the EGR effective flow at the EGR valve position is 100% less than a no-flow limit (S23), wherein if the EGR effective flow at the EGR valve position is 100% less than the no-flow limit, the EGR effective flow is diagnosed as EGR blockage (S24). [7] Method according to claim 1, further comprising confirming whether the EGR effective flow at the 0% position of the EGR valve exceeds a maximum flow limit (S25), wherein if the EGR effective flow at the 0% position of the EGR valve exceeds the maximum flow limit, the EGR effective flow is diagnosed as EGR opening (S27). [8] Method according to claim 1, wherein after measuring the EGR gas temperature (S15) the degree of temperature increase of the EGR gas is normalized to the exhaust gas energy. [9] Method according to claim 1, wherein the EGR gas temperature rise condition is a case in which an EGR differential pressure exceeds a reference differential pressure by checking the EGR differential pressure (S14). [10] Method according to claim 1, wherein the EGR gas temperature rise condition is a case in which an exhaust gas pressure exceeds a predetermined reference. [11] Method according to claim 1, wherein the EGR gas temperature rise condition is a case in which an engine load exceeds a predetermined reference. [12] Method according to claims 9 to 11, further comprising confirming whether the EGR effective flow at the 100% position of the EGR valve is less than a no-flow limit (S23), wherein if the EGR effective flow at the EGR valve position is less than the no-flow limit, the EGR effective flow is diagnosed as EGR blockage (S24). [13] Method according to claim 12, further comprising confirming whether the EGR effective flow at the 0% position of the EGR valve exceeds a maximum flow limit (S25), wherein if the EGR effective flow at the 0% position of the EGR valve exceeds the maximum flow limit, the EGR effective flow is diagnosed as EGR opening (S27).

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