Method and apparatus for diagnosing gas flow control valves of internal combustion engines

Abstract

When a rationality assessment with fail-safe controls makes a negative result before a CSERS assessment, the CSERS assessment may not be able to complete correctly. [Solution] The TCV function diagnosis and rationality diagnosis are performed repeatedly during normal operation, and the CSERS diagnosis is performed with the cold condition as a weighted condition. The time required for the TCV function diagnosis and rationality diagnosis is approximately equal, and both diagnoses are completed at time t3. The time required for the CSERS diagnosis is set to be shorter so that its completion always precedes the completion of the TCV function diagnosis and rationality diagnosis, and it is completed at time t2.

Description

Technical Field

[0001] This invention relates to a failure diagnosis of a gas flow control valve disposed upstream of an intake port for variably controlling the gas flow in a cylinder.

Background Art

[0002] For example, in an internal combustion engine mounted in an automobile, for ensuring safety and exhaust performance, as is well known, for various control systems, failure diagnosis targeting actuators, sensors, control circuits, etc. constituting the control system is obligatory under laws and regulations of various countries.

[0003] Patent Document 1 discloses performing a failure diagnosis on a gas flow control valve (for example, a tumble control valve) disposed upstream of an intake port for variably controlling the gas flow in a cylinder.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In current internal combustion engines, for one device, for example, a gas flow control valve, multiple diagnoses with different main purposes and compliance regulations may be executed in parallel, and there is a concern of mutual competition. For example, if a gas flow control valve is determined to be abnormal by a certain diagnosis and the opening degree of the gas flow control valve is fixed by fail-safe control associated with the abnormality determination, there is a possibility that other diagnoses being executed in parallel may not reach the diagnosis completion.

Means for Solving the Problems

[0006] This invention relates to a gas flow control valve positioned upstream of an intake port for variable control of gas flow within a cylinder, and provides a diagnostic method for a gas flow control valve of an internal combustion engine, which involves comparing a target opening degree given as a control target with the actual opening degree detected by a sensor during the operation of the internal combustion engine, and diagnosing the gas flow control valve. A first diagnostic process is performed regardless of whether the engine is warm or cold, and in the event of an abnormality detection, it commands fail-safe control, including fixing the opening degree of the gas flow control valve. The second diagnosis is performed under the condition that the vehicle is in a cold state, and its completion is legally required. Includes, When both diagnoses are performed in parallel under cold conditions, the required time and start timing for each diagnosis were set so that the completion of the second diagnosis precedes the completion of the first diagnosis.

[0007] In this way, when the first and second diagnoses are performed in parallel under cold conditions, the second diagnosis will always be completed first. Therefore, for example, if there is some abnormality in the control system of the gas flow control valve, the legally required completion of the diagnosis can be achieved without conflicting with the fail-safe control (fixing the opening of the gas flow control valve) associated with the abnormality detection by the first diagnosis. [Effects of the Invention]

[0008] This invention reliably avoids the phenomenon in which a second diagnosis performed when the vehicle is in a cold state conflicts with the first diagnosis, preventing the completion of the legally required diagnosis. [Brief explanation of the drawing]

[0009] [Figure 1] A diagram illustrating the system configuration of an internal combustion engine according to this invention. [Figure 2] A time chart showing the diagnostic operation of the tumble control valve during cold starts. [Figure 3] A time chart showing the operation of the comparative example. [Modes for carrying out the invention]

[0010] Hereinafter, an embodiment of this invention will be described in detail with reference to the drawings. Figure 1 is an explanatory diagram showing the schematic configuration of an internal combustion engine 1 in an embodiment to which this invention is applied. The internal combustion engine 1 is, for example, an internal combustion engine that serves as a driving source for an automobile, but it may also be an internal combustion engine for power generation in a series hybrid vehicle. The internal combustion engine 1 in this embodiment is a four-stroke cycle spark-ignition internal combustion engine (a so-called gasoline engine), and each cylinder is equipped with an intake valve 2, an exhaust valve 3, and a spark plug 4. Furthermore, as a direct injection type internal combustion engine, a fuel injector 5 that injects fuel into the cylinder is positioned at an appropriate location inside the cylinder. The fuel injector 5 is supplied with fuel adjusted to a predetermined fuel pressure by a pressure regulator (not shown), and when the fuel injector 5 opens in response to a drive pulse signal from the engine controller 9, an amount of fuel corresponding to the pulse width is injected.

[0011] An electronically controlled throttle valve 10, whose opening degree is controlled by a control signal from an engine controller 9, is installed upstream of the collector portion 8 of the intake passage 7 connected to the intake port 6 of each cylinder. An air flow meter 11 for detecting the amount of intake air is installed upstream of the throttle valve 10, and an air cleaner (not shown) is installed further upstream.

[0012] Here, a tumble control valve 12 is provided at the inlet of the intake port 6 of each cylinder as a gas flow control valve, covering, for example, the lower half of the passage cross-section. The tumble control valve 12 is configured to rotate about a rotation axis along the cylinder row direction, and its opening degree is controlled via an actuator 25 driven by a control signal from the engine controller 9. The actual opening degree of the tumble control valve 12 is detected by a position sensor 26. For example, in one embodiment, the actuator 25 is linked to one end of a rotation axis common to multiple cylinders, and the position sensor 26 is linked to the other end. When the tumble control valve 12 is closed, the intake air flowing into the cylinder through the intake valve 2 flows to one side at high speed, thus increasing the intensity of the tumble flow inside the cylinder. In one embodiment, the tumble control valve 12 is a so-called normally closed type, and when the actuator 25 is not driven by the engine controller 9, it is in the closed position as shown in the figure. In one embodiment, the tumble control valve 12 is controlled in stages to multiple opening degrees.

[0013] The exhaust ports 13 of each cylinder converge into a single exhaust passage 14, and a three-way catalytic converter 15 for exhaust gas purification is provided in this exhaust passage 14. The three-way catalytic converter 15 is a so-called monolithic ceramic catalyst, for example, a monolithic ceramic body with fine passages formed therein, coated with a catalytic layer containing a catalytic metal. The three-way catalytic converter 15 may also include a configuration that includes multiple catalysts arranged in series (for example, a manifold catalyst and an underbody catalyst).

[0014] An air-fuel ratio sensor 19 for detecting the exhaust air-fuel ratio is positioned on the inlet side of the three-way catalytic converter 15 in the exhaust passage 14, that is, upstream of the three-way catalytic converter 15.

[0015] The detection signals from the air-fuel ratio sensor 19, the air flow meter 11, and the position sensor 26 are input to the engine controller 9. The engine controller 9 also receives detection signals from numerous other sensors, including a crank angle sensor 21 for detecting engine rotational speed, a water temperature sensor 22 for detecting coolant temperature, an ambient temperature sensor 23 for detecting ambient temperature, and an accelerator pedal position sensor 24 for detecting the amount the accelerator pedal is pressed by the driver. Based on these input signals, the engine controller 9 optimally controls the fuel injection amount and timing by the fuel injector 5, the ignition timing by the spark plug 4, the opening of the throttle valve 10, the opening of the tumble control valve 12, and so on.

[0016] The engine controller 9 performs fault diagnosis of the tumble control valve 12 as one of the various controls of the internal combustion engine 1. Faults or abnormalities in the tumble control valve 12 may include abnormalities in the actuator 25, abnormalities in the position sensor 26, or software abnormalities in the control system. The diagnosis of the tumble control valve 12, which is the main part of this invention, will be described below.

[0017] There are three types of diagnoses that target the tumble control valve 12. The first is a TCV function diagnosis aimed at confirming that the entire control system of the tumble control valve 12 is operating normally. The TCV function diagnosis is reset when the target opening of the tumble control valve 12 changes based on the operating conditions and is performed while the target opening is stable. In other words, the diagnosis starts immediately after the target opening of the tumble control valve 12 changes, and if the target opening does not change for the time required for the diagnosis, the diagnosis is completed. If the target opening changes before the diagnosis is completed, the previous diagnosis is reset, and the next diagnosis starts immediately afterward. The TCV function diagnosis compares the target opening set by the engine controller 9 based on the operating conditions of the internal combustion engine 1 with the actual opening detected by the position sensor 26, and determines that there is an abnormality if the two deviate from each other.

[0018] When an abnormality is determined in this TCV function diagnosis, in order to avoid combustion deterioration due to an abnormality in the tumble control valve 12, a command for a predetermined fail-safe control is output. The predetermined fail-safe control executed by the engine controller 9 includes three types: driving restrictions such as vehicle speed and output, combustion restrictions based on the tumble flow, and fixing of the tumble control valve 12. When fixing the tumble control valve 12, the drive of the actuator 25 is stopped (the target opening becomes 0), so the tumble control valve 12 is in the fully closed position as long as there is no sticking of the valve body or the like. The TCV function diagnosis is executed not only when the target opening is fully closed or fully open but also when it is at an intermediate opening. That is, during the operation of the internal combustion engine 1, regardless of the warm-up state / cold state, the TCV function diagnosis is repeatedly executed.

[0019] The second diagnosis is a Rationality diagnosis mainly for detecting an abnormality in the position sensor 26. Similar to the TCV function diagnosis, the Rationality diagnosis is reset when the target opening of the tumble control valve 12 changes based on the operating conditions and is performed while the target opening is stable. In other words, the diagnosis is started immediately after the target opening of the tumble control valve 12 changes, and if the target opening does not change during the time required for the diagnosis, the diagnosis is completed. If the target opening changes before the diagnosis is completed, the previous diagnosis is reset and the next diagnosis is started immediately. However, different from the TCV function diagnosis, the Rationality diagnosis is executed only when the target opening is fully closed or fully open. The diagnosis method is the same as that of the TCV function diagnosis. The engine controller 9 compares the target opening (fully closed or fully open) set based on the operating conditions of the internal combustion engine 1 with the actual opening detected by the position sensor 26, and determines that there is an abnormality if the two deviate.

[0020] When an abnormality is determined in this rationality diagnosis, in order to avoid combustion deterioration due to an abnormality in the tumble control valve 12, a command for a predetermined fail-safe control is also output. As the fail-safe control associated with the abnormality determination by this rationality diagnosis, fixing of the tumble control valve 12 (target opening degree is 0) is included. When fixing the tumble control valve 12, the driving of the actuator 25 is stopped, so the tumble control valve 12 is in the fully closed position as long as there is no sticking of the valve body or the like. The rationality diagnosis is repeatedly executed during the operation of the internal combustion engine 1 regardless of the warm-up state / cold state, on the condition that the target opening degree is fully closed or fully open.

[0021] The above TCV function diagnosis and rationality diagnosis correspond to the "first diagnosis" in the claims.

[0022] The third diagnosis is the CSERS diagnosis corresponding to the "second diagnosis" in the claims. This CSERS diagnosis is a diagnosis aimed at confirming that there is no abnormality in the variable devices and control systems that affect the warm-up performance (in other words, the exhaust purification performance) of the three-way catalyst 15 after a cold start. When the internal combustion engine 1 is in a cold state, it is legally obligatory to diagnose the tumble control valve 12 as one of the variable devices. Furthermore, correct completion of the diagnosis is essential legally.

[0023] The CSERS diagnosis, like the TCV function diagnosis and rationality diagnosis, is reset when the target opening of the tumble control valve 12 changes based on the operating conditions, and is performed while the target opening is stable. In other words, the diagnosis starts immediately after the target opening of the tumble control valve 12 changes, and if the target opening does not change for the time required for the diagnosis, the diagnosis is completed. If the target opening changes before the diagnosis is completed, the previous diagnosis is reset, and the next diagnosis starts immediately. However, the CSERS diagnosis is performed only when the internal combustion engine 1 is in a cold state. The diagnostic method is the same as the TCV function diagnosis, comparing the target opening (including intermediate opening) set by the engine controller 9 based on the operating conditions of the internal combustion engine 1 with the actual opening detected by the position sensor 26, and if the two deviate, it is determined to be abnormal. In the CSERS diagnosis, if it is determined that the tumble control valve 12 is abnormal, the abnormal determination is recorded as a fault code (DTC), but no active fail-safe control is performed.

[0024] As described above, the CSERS diagnosis is performed only while the internal combustion engine 1 is in a cold state. In one embodiment, the CSERS diagnosis is performed when three conditions are simultaneously met: the soak time since the last shutdown is longer than a predetermined time; the ambient temperature is higher than a predetermined temperature (set below freezing point); and the difference between the coolant temperature and the ambient temperature is less than a predetermined temperature difference. Therefore, for example, after a cold start, the CSERS diagnosis will be repeatedly performed in parallel with the TCV function diagnosis and rationality diagnosis until the difference between the coolant temperature and the ambient temperature reaches a predetermined temperature difference.

[0025] Next, referring to the time chart in Figure 2, the required times for the three diagnostic tests when the internal combustion engine 1 is in a cold state will be explained. The time chart in Figure 2 shows (a) the target opening of the tumble control valve 12, (b) the start of the rationality diagnostic test, (c) the result of the rationality diagnostic test, (d) the start of the TCV function diagnostic test and the CSERS diagnostic test, (e) the result of the TCV function diagnostic test, and (f) the result of the CSERS diagnostic test. In the example in Figure 2, at time t1, the target opening changes from fully closed to fully open due to a change in the operating conditions of the internal combustion engine 1. Due to this change in the target opening, the TCV function diagnostic test and the CSERS diagnostic test start substantially simultaneously immediately after time t1. The rationality diagnostic test requires a predetermined time for the diagnostic permission determination, resulting in a delayed diagnostic start timing compared to the diagnostic start timings of the TCV function diagnostic test and the CSERS diagnostic test.

[0026] The time required for each diagnosis (the time from time t1 when the target opening changes until the NG / OK diagnosis result is obtained) is the sum of the time from time t1 until the diagnosis start time (this is called the diagnosis permission time) and the time from the diagnosis start time until the diagnosis result is obtained (i.e., diagnosis is completed) (this is called the diagnosis processing time). In this embodiment, when the three diagnoses are performed in parallel, the respective diagnosis permission time and diagnosis processing time are set so that the completion of the CSERS diagnosis always precedes the completion of the TCV function diagnosis and the rationality diagnosis.

[0027] As mentioned above, the diagnostic allow time for TCV function diagnosis and CSERS diagnosis is very short, equivalent to a minute amount of time, such as a program calculation cycle. For illustrative purposes, the diagnostic processing time required for the TCV function diagnosis is set to, for example, 5000ms. Therefore, the time required for the TCV function diagnosis is approximately 5000ms. In contrast, the diagnostic allow time for the rationality diagnosis is relatively long, for example, 1000ms. The diagnostic processing time required for the rationality diagnosis is set to, for example, 4000ms. Therefore, the time required for the rationality diagnosis is approximately 5000ms, which is about the same as the time required for the TCV function diagnosis.

[0028] In contrast, the diagnostic processing time required for the CSERS diagnostic calculation is set to 4700ms, which is 300ms shorter than the diagnostic processing time for the TCV function diagnostic, in order to allow for an appropriate margin of error when the diagnosis is completed.

[0029] Therefore, the CSERS diagnosis is completed at time t2 in Figure 2, and the TCV function diagnosis and rationality diagnosis are completed at a later time t3.

[0030] In the example shown in Figure 2, there is an abnormality in the tumble control valve 12, resulting in a CSERS diagnosis of NG at time t2, and NG diagnoses for both TCV function diagnosis and rationality diagnosis at time t3.

[0031] In this way, the completion of the CSERS diagnosis always precedes the completion of the TCV function diagnosis and rationality diagnosis, as the respective diagnosis permission time and diagnosis processing time are set accordingly, ensuring that the CSERS diagnosis is always completed correctly.

[0032] Figure 3 shows a time chart as a comparative example, where the TCV function diagnosis or rationality diagnosis is completed before the CSERS diagnosis. In this example, at time t11, the target opening changes from fully closed to fully open, but it is assumed that there is an abnormality in the tumble control valve 12 and the position sensor 26 detects the fully closed position. Therefore, when the rationality diagnosis is completed at time t12, an NG judgment is made. Following this NG judgment, fail-safe control is executed, and the target opening becomes fully closed in order to stop the driving of the tumble control valve 12. As a result, a state occurs where the target opening and the actual opening (detected opening) match, and it may be possible that the CSERS diagnosis, which is completed later at time t13, cannot correctly make an NG judgment.

[0033] Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment, and various modifications are possible. For example, the tumble control valve to be diagnosed is not limited to the illustrated configuration, but may be any configuration. Also, the gas flow control valve may be a swirl control valve. Furthermore, although the above example described the diagnosis when the target opening is fully open, the same applies to the diagnosis at intermediate openings. [Explanation of Symbols]

[0034] 1…Internal combustion engine 2…Intake valve 5…Fuel injector 6…Intake port 9…Controller 12... Tumble control valve 15...Three-way catalyst 22...Water temperature sensor 23... Outdoor temperature sensor 25… Actuator 26... Position sensor

Claims

1. A method for diagnosing a gas flow control valve of an internal combustion engine, which is positioned upstream of an intake port to variably control the gas flow within a cylinder, and which diagnoses the gas flow control valve of an internal combustion engine by comparing a target opening degree given as a control target with the actual opening degree detected by a sensor during the operation of the internal combustion engine, A first diagnostic process is performed regardless of whether the engine is warm or cold, and in the event of an abnormality detection, it commands fail-safe control, including fixing the opening degree of the gas flow control valve. The second diagnosis, which is performed under the condition that the vehicle is in a cold state and whose completion is legally required, Includes, When both diagnoses are performed in parallel under cold conditions, the processing time and start timing of each diagnosis are set so that the completion of the second diagnosis precedes the completion of the first diagnosis. Diagnostic methods for gas flow control valves in internal combustion engines.

2. Furthermore, the first diagnosis described above is, A diagnostic procedure to confirm that the entire control system of the gas flow control valve is functioning correctly, The diagnostics are primarily performed under specific target openings to detect abnormalities in the above sensors, This includes two diagnostics that can be performed in parallel, A method for diagnosing a gas flow control valve of an internal combustion engine according to claim 1.

3. The second diagnostic method described above does not involve fixing the opening degree of the gas flow control valve when an abnormality is detected. A method for diagnosing a gas flow control valve of an internal combustion engine according to claim 1.

4. The second diagnosis described above is performed assuming the vehicle is in a cold state when three conditions are simultaneously met: the soak time since the last shutdown is longer than a predetermined time; the ambient temperature is higher than a predetermined temperature set below freezing; and the difference between the coolant temperature and the ambient temperature is less than a predetermined temperature difference. A method for diagnosing a gas flow control valve of an internal combustion engine according to claim 1.

5. As the gas flow control valve mentioned above, the tumble control valve will be the target of the diagnosis. A method for diagnosing a gas flow control valve of an internal combustion engine according to claim 1.

6. A diagnostic device for a gas flow control valve of an internal combustion engine, which is positioned upstream of the intake port to variably control the gas flow within the cylinder, and which diagnoses the gas flow control valve by comparing a target opening degree given as a control target with the actual opening degree detected by a sensor during the operation of the internal combustion engine, A first diagnostic process is performed regardless of whether the engine is warm or cold, and in the event of an abnormality detection, it commands fail-safe control, including fixing the opening degree of the gas flow control valve. The second diagnosis, which is performed under the condition that the vehicle is in a cold state and whose completion is legally required, Includes, When both diagnoses are performed in parallel under cold conditions, the processing time and start timing of each diagnosis are set so that the completion of the second diagnosis precedes the completion of the first diagnosis. A diagnostic device for gas flow control valves in internal combustion engines.

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