Knock signal credibility detection method, system, engine and motor vehicle

Abstract

The present application relates to knock signal credibility detection method, system, engine and motor vehicle, during continuous non-combustion window and combustion window, the signal of knock sensor is acquired, the background noise signal of combustion window is extracted, and the signal corresponding to the set range before the compression top dead center of the cylinder in the non-combustion window is recorded as Pre window signal;Pre window signal is credible, and when consistency calibration is carried out, if the difference between the background noise signal of the current cylinder combustion window and the weighted value of the background noise of other cylinder combustion window exceeds the set threshold value, the signal obtained by knock sensor in combustion window drifts;When not consistency calibration is carried out, if the difference between the background noise signal of the current cylinder combustion window and the Pre window signal exceeds the set threshold value, the signal obtained by knock sensor in combustion window drifts, and when the drift frequency exceeds the limit, the corresponding knock determination result is not credible. The signals of non-combustion window and multiple knock sensor signals are mutually checked.

Description

Technical Field

[0001] This invention relates to the field of engine control technology, specifically to a method, system, engine, and motor vehicle for detecting the reliability of knock signals. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Knock sensors detect knocking by monitoring vibration signals during engine operation. If knocking combustion is detected, the engine will be protected by adjusting ignition to prevent continuous knocking combustion, such as by cutting off fuel, enriching the air-fuel mixture, or limiting the throttle.

[0004] The knock sensor collects a voltage signal at the combustion window of the corresponding cylinder, and processes the signal to determine whether knock has occurred. Simultaneously, knock sensor diagnostics are also performed within this window; therefore, the determination and diagnosis of knock signals depend on the signal conditions at the combustion window. If, under certain circumstances, the signal acquired by the knock sensor at the combustion window is interfered with, it will affect the knock determination. Summary of the Invention

[0005] To address the technical problems mentioned above, this invention provides a method, system, engine, and motor vehicle for detecting the reliability of knock signals. It uses signals from a non-combustion window and multiple knock sensor signals for mutual verification to assist in judging the quality of knock signals and to perform corresponding downgrading when a problem is detected.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The first aspect of the present invention provides a method for detecting the reliability of detonation signals, comprising the following steps:

[0008] During the continuous non-combustion window and combustion window, the signal from the knock sensor is acquired, the background noise signal of the combustion window is extracted, and the signal corresponding to the set range before the top dead center of the cylinder compression in the non-combustion window is extracted, which is denoted as the Pre window signal.

[0009] The Pre window signal is reliable, and after consistency calibration, if the difference between the weighted value of the background noise signal of the current cylinder combustion window and the background noise of other cylinder combustion windows exceeds the set threshold, the signal obtained by the knock sensor in the combustion window will drift.

[0010] The Pre window signal is reliable, but it has not been calibrated for consistency. If the difference between the background noise signal of the current cylinder combustion window and the Pre window signal exceeds the set threshold, the signal obtained by the knock sensor in the combustion window will drift.

[0011] The number of times the signal obtained by the knock sensor in the combustion window drifts exceeds the limit, and the corresponding knock judgment result is unreliable. The ignition advance angle is then corrected.

[0012] Furthermore, the ignition advance angle is corrected, specifically by using the knock back angle to correct the ignition advance angle. Knock back angle = correction coefficient x * average knock back angle of other cylinders + correction coefficient y * maximum knock back angle of other cylinders.

[0013] Furthermore, if the Pre window signal is unreliable, the ignition advance angle is corrected.

[0014] Furthermore, if the deviation between the acquired Pre window signal and the preset value does not exceed the set value, the Pre window signal is reliable; if the deviation exceeds the set value, the Pre window signal is unreliable.

[0015] Furthermore, if the Pre window signal is reliable and the engine has undergone consistency calibration, the difference between the weighted value of the background noise signal of the current cylinder combustion window and the Pre window signal of other cylinders exceeds the set threshold, causing the signal obtained by the knock sensor in the combustion window to drift.

[0016] Furthermore, the combustion window is the time period from spark plug ignition to the end of combustion in the cylinder, during which the crankshaft rotates from x° to y°.

[0017] Furthermore, the non-combustion window is the set range before the cylinder compression top dead center, and the corresponding crankshaft angle range is z°-x°, where the crankshaft rotates to x° to correspond to the cylinder compression top dead center.

[0018] A second aspect of the present invention provides a knock signal reliability detection system, comprising:

[0019] The signal acquisition unit is configured to acquire the signal from the knock sensor during the continuous non-combustion window and combustion window, extract the background noise signal of the combustion window, and the signal corresponding to a set range before the top dead center of the cylinder compression in the non-combustion window, which is denoted as the Pre window signal.

[0020] The knock signal reliability detection unit is configured such that: if the Pre window signal is reliable and after consistency calibration, if the difference between the weighted value of the background noise signal of the current cylinder combustion window and the background noise of other cylinder combustion windows exceeds a set threshold, the signal obtained by the knock sensor in the combustion window will drift.

[0021] The knock signal reliability detection unit is also configured such that: if the difference between the background noise signal of the current cylinder combustion window and the Pre window signal exceeds a set threshold when the Pre window signal is reliable but has not been calibrated, the signal obtained by the knock sensor in the combustion window will drift.

[0022] The correction unit is configured to correct the ignition advance angle when the number of times the signal obtained by the knock sensor in the combustion window drifts exceeds the limit and the corresponding knock judgment result is unreliable.

[0023] A third aspect of the present invention provides an engine equipped with a controller that performs the steps in the above-described knock signal reliability detection method.

[0024] A fourth aspect of the present invention provides a motor vehicle having an onboard computer that performs the steps in the above-described knock signal reliability detection method.

[0025] Compared with existing technologies, one or more of the above technical solutions have the following beneficial effects:

[0026] Traditional signal processing methods rely on signals acquired by knock sensors during the combustion window to determine knock occurrence. However, interference with these signals can affect knock detection. This solution, however, uses signals from outside the combustion window, along with cross-verification of signals from multiple knock sensors, to aid in assessing knock signal quality. If a drift is detected in the knock sensor signal acquired during the combustion window, it is considered interfered with, and the knock detection result is deemed unreliable. Degradation control is implemented by correcting the ignition advance angle, enabling better engine knock protection even when knock sensor signals are interfered with and misjudgments are possible. Attached Figure Description

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0028] Figure 1 This is a schematic diagram of the detonation signal reliability detection process provided by one or more embodiments of the present invention. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the scope of exemplary embodiments of the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] Terminology Explanation:

[0033] Knock: refers to the process in which the air-fuel mixture in a part of the engine cylinder spontaneously combusts before the normal flame front arrives, resulting in two or more flames (ignition + spontaneous combustion) in the cylinder acting violently and impacting the cylinder wall, piston, etc.

[0034] The combustion window refers to the time period during which combustion occurs in a specific cylinder within an engine's working cycle. Specifically, it refers to the time from spark plug ignition to the end of combustion.

[0035] The process by which a knock sensor acquires signals within the combustion window and detects and judges knock is a complex mechanism combining mechanical vibration detection, signal processing, and real-time control. The combustion window is the time period from spark plug ignition to the end of combustion in a cylinder (usually a few milliseconds to tens of milliseconds), while knock usually occurs in the middle and late stages of combustion (i.e., about 10 to 30 degrees crankshaft rotation after ignition). At this time, abnormal superposition of pressure waves in the cylinder can easily trigger knock.

[0036] When an engine experiences high-frequency vibrations (typically 5–20 kHz) due to knocking, the knock sensor generates a signal (electrical or magnetic) proportional to the vibration intensity. The ECU bandpass-filters the sensor output signal, retaining only the knocking characteristic frequency range (e.g., 5–15 kHz) and filtering out other engine mechanical noises (such as low-frequency vibrations from valve opening and closing, piston movement, etc.). Through threshold comparison, frequency analysis, and duration determination, the ECU determines that knocking has occurred in the cylinder. The ECU then issues corresponding commands based on the current engine operating conditions to suppress knocking and prevent mechanical damage to the engine, such as retarding ignition timing, adjusting the air-fuel ratio, and controlling turbocharging.

[0037] As described in the background section, the knock sensor collects a voltage signal in the combustion window of the corresponding cylinder to determine whether knock has occurred. The diagnostics of the knock sensor also take place within this window; therefore, the determination and diagnosis of knock signals depend on the signal conditions in the combustion window. If, under certain circumstances, the signal acquired by the knock sensor in the combustion window is interfered with, the reliability of the signal cannot be determined, affecting the knock determination.

[0038] Therefore, the following embodiments provide a method, system, engine, and motor vehicle for detecting the reliability of knock signals. The method uses signals from the non-combustion window and multiple knock sensor signals to cross-verify each other, which assists in judging the quality of knock signals and performs corresponding downgrading when a problem is found.

[0039] Example 1:

[0040] In the prior art, the signal obtained by the knock sensor during the combustion window is used as the basis for determining whether knock has occurred. In this embodiment, in addition to considering the combustion window, the non-combustion window period before the combustion window is also considered to obtain the Pre-window signal. Here, the Pre-window signal refers to the signal obtained by the knock sensor within a set range before the top dead center of the cylinder compression.

[0041] The combustion window is the time period from spark plug ignition to the end of combustion in the cylinder. This time period corresponds to the rotation angle of the crankshaft, that is, when the crankshaft rotates from x° to y°, the cylinder goes from spark plug ignition to the end of combustion.

[0042] Top dead center (TDC) of the cylinder is the highest point the piston reaches during the compression stroke, at which point the cylinder volume is smallest and the pressure is greatest. Spark plug ignition timing is usually close to TDC, but not always at it. The choice of ignition timing depends on the engine design and operating conditions, aiming to ignite the air-fuel mixture at the optimal moment for efficient combustion. Therefore, ignition timing may be before (advanced ignition) or after (delayed ignition), specifically adjusted by the engine control unit (ECU) based on factors such as engine speed and load.

[0043] The Pre window signal obtained in this embodiment refers to the signal obtained by the knock sensor within a set range before the cylinder compression top dead center. The set range can be expressed as the range of angles through which the crankshaft rotates. For example, assuming that the "cylinder compression top dead center" is 0°, the combustion window is 0°-a° and the non-combustion window is b°-0°. Here, a is a positive value and b is a negative value.

[0044] The main implementation process of this embodiment is as follows:

[0045] When the deviation between the current Pre window signal and the preset value of the test bench is within a certain range, the Pre window signal is considered reliable.

[0046] If the consistency of the knock signal of each cylinder has been well ensured through calibration or strategic means in the early stage, the background noise signal of the current cylinder combustion window can be compared with the weighted value of the background noise of the combustion window of other cylinders, or the background noise signal of the current cylinder combustion window can be compared with the weighted value of the Pre window signal of other cylinders. If either comparison method exceeds the limit, the knock signal of the combustion window is considered to have drifted.

[0047] Current technology corrects the ignition advance angle when knocking occurs. However, since knocking signals are unreliable and the knocking determination of the current cylinder is also unreliable, in problematic operating conditions, the ignition advance angle calculated for the problematic cylinder is no longer used for correction. Instead, the knock retraction angle of other cylinders without problems is used as the correction for the problematic cylinder. The knock retraction angle is calculated as correction factor x * average knock retraction angle of other cylinders + correction factor y * maximum knock retraction angle of other cylinders. The correction factor can be calibrated.

[0048] If the consistency of knock signals in each cylinder is not ensured through calibration or strategic means in the early stage, only the background noise signal of the current cylinder's combustion window and the Pre window signal are compared. When a problem condition and a problem cylinder are identified, the same downgrade operation as described above is performed.

[0049] A method for detecting the reliability of detonation signals includes the following steps:

[0050] During the continuous non-combustion window and combustion window, the signal from the knock sensor is acquired, the background noise signal of the combustion window is extracted, and the signal corresponding to the set range before the top dead center of the cylinder compression in the non-combustion window is extracted, which is denoted as the Pre window signal.

[0051] The Pre window signal is reliable, and after consistency calibration, if the difference between the weighted value of the background noise signal of the current cylinder combustion window and the background noise of other cylinder combustion windows exceeds the set threshold, the signal obtained by the knock sensor in the combustion window will drift.

[0052] The Pre window signal is reliable, but it has not been calibrated for consistency. If the difference between the background noise signal of the current cylinder combustion window and the Pre window signal exceeds the set threshold, the signal obtained by the knock sensor in the combustion window will drift.

[0053] The number of times the signal obtained by the knock sensor in the combustion window drifts exceeds the limit, and the corresponding knock judgment result is unreliable. The ignition advance angle is then corrected.

[0054] As a further implementation method, the ignition advance angle is corrected, specifically by using the knock back angle to correct the ignition advance angle. The knock back angle = correction coefficient x * average knock back angle of other cylinders + correction coefficient y * maximum knock back angle of other cylinders.

[0055] As a further implementation, when the Pre window signal is unreliable, the ignition advance angle is corrected.

[0056] As a further implementation, if the deviation between the acquired Pre window signal and the preset value does not exceed the set value, the Pre window signal is reliable; if the deviation exceeds the set value, the Pre window signal is unreliable.

[0057] As a further implementation, the Pre window signal is reliable, and when the engine is calibrated for consistency, if the difference between the weighted value of the background noise signal of the current cylinder combustion window and the Pre window signal of other cylinders exceeds a set threshold, the signal obtained by the knock sensor in the combustion window will drift.

[0058] Specifically, such as Figure 1 As shown: When |current Pre-window signal - bench preset value| < threshold 1, the Pre-window signal is reliable; if it is not less than threshold 1, the Pre-window signal is considered unreliable.

[0059] When the Pre window signal is reliable, determine whether the engine has undergone consistency calibration, specifically:

[0060] If the calibration phase has already performed consistency calibration on the signals of each cylinder, or if the consistency correction strategy has been activated, and if |background noise signal of the current cylinder combustion window - fac1 * weighted value of Pre window signals of each cylinder| > threshold 2, or |background noise signal of the current cylinder combustion window - fac2 * weighted value of background noise of the combustion window of each cylinder| > threshold 3, then the knock signal of the combustion window has drifted; if any of the above judgments does not exceed the corresponding threshold, then the knock signal of the combustion window has not drifted.

[0061] If the calibration phase does not perform consistent calibration on the signals of each cylinder, or does not activate the consistency correction strategy, but |background noise signal of the current cylinder combustion window - current cylinder Pre window signal| > threshold 4, then the knock signal of the combustion window will drift.

[0062] When the knock signal in the combustion window drifts, the number of times it exceeds the threshold under each operating condition of the current cylinder is counted. If the count exceeds the limit, the background noise signal of the current cylinder has a problem under the corresponding operating condition, and the corresponding knock judgment result is unreliable. If the Pre window signal is unreliable, the corresponding knock judgment result is also considered unreliable.

[0063] Therefore, for the cylinder with the problem, the ignition advance angle is no longer used for correction. Instead, the knock retraction angle of other cylinders without problems is used as the correction for the problematic cylinder. Knock retraction angle = fac4 * average knock retraction angle of other cylinders + fac5 * maximum knock retraction angle of other cylinders.

[0064] If the number of counts has not exceeded the limit, return to the previous judgment.

[0065] In this embodiment, fac1-fac5 are all correction coefficients (i.e. weighting coefficients), where fac4 corresponds to correction coefficient x and fac5 corresponds to correction coefficient y. All correction coefficients can be calibrated through experiments, simulations or other similar methods.

[0066] Traditional signal processing methods rely on signals acquired by knock sensors during the combustion window to determine knock occurrence. However, interference with these signals can affect knock detection. This solution, however, uses signals from outside the combustion window, along with cross-verification of signals from multiple knock sensors, to aid in assessing knock signal quality. If a drift is detected in the knock sensor signal acquired during the combustion window, it is considered interfered with, and the knock detection result is deemed unreliable. Degradation control is implemented by correcting the ignition advance angle, enabling better engine knock protection even when knock sensor signals are interfered with and misjudgments are possible.

[0067] Example 2:

[0068] A second aspect of the present invention provides a knock signal reliability detection system, comprising:

[0069] The signal acquisition unit is configured to acquire the signal from the knock sensor during the continuous non-combustion window and combustion window, extract the background noise signal of the combustion window, and the signal corresponding to a set range before the top dead center of the cylinder compression in the non-combustion window, which is denoted as the Pre window signal.

[0070] The knock signal reliability detection unit is configured such that: if the Pre window signal is reliable and after consistency calibration, if the difference between the weighted value of the background noise signal of the current cylinder combustion window and the background noise of other cylinder combustion windows exceeds a set threshold, the signal obtained by the knock sensor in the combustion window will drift.

[0071] The knock signal reliability detection unit is also configured such that: if the difference between the background noise signal of the current cylinder combustion window and the Pre window signal exceeds a set threshold when the Pre window signal is reliable but has not been calibrated, the signal obtained by the knock sensor in the combustion window will drift.

[0072] The correction unit is configured to correct the ignition advance angle when the number of times the signal obtained by the knock sensor in the combustion window drifts exceeds the limit and the corresponding knock judgment result is unreliable.

[0073] Traditional signal processing methods rely on signals acquired by knock sensors during the combustion window to determine knock occurrence. However, interference with these signals can affect knock detection. This solution, however, uses signals from outside the combustion window, along with cross-verification of signals from multiple knock sensors, to aid in assessing knock signal quality. If a drift is detected in the knock sensor signal acquired during the combustion window, it is considered interfered with, and the knock detection result is deemed unreliable. Degradation control is implemented by correcting the ignition advance angle, enabling better engine knock protection even when knock sensor signals are interfered with and misjudgments are possible.

[0074] Example 3:

[0075] An engine equipped with a controller that performs the steps in the above-described method for detecting the reliability of knock signals.

[0076] The controller is not limited to a specific structural form. It can call the signal obtained by the knock sensor, process the corresponding signal in the combustion window and non-combustion window, and issue the corresponding command to the engine.

[0077] Traditional signal processing methods rely on signals acquired by knock sensors during the combustion window to determine knock occurrence. However, interference with these signals can affect knock detection. This solution, however, uses signals from outside the combustion window, along with cross-verification of signals from multiple knock sensors, to aid in assessing knock signal quality. If a drift is detected in the knock sensor signal acquired during the combustion window, it is considered interfered with, and the knock detection result is deemed unreliable. Degradation control is implemented by correcting the ignition advance angle, enabling better engine knock protection even when knock sensor signals are interfered with and misjudgments are possible.

[0078] Example 4:

[0079] A motor vehicle has an onboard computer that performs the steps in the above-described knock signal reliability detection method.

[0080] Traditional signal processing methods rely on signals acquired by knock sensors during the combustion window to determine knock occurrence. However, interference with these signals can affect knock detection. This solution, however, uses signals from outside the combustion window, along with cross-verification of signals from multiple knock sensors, to aid in assessing knock signal quality. If a drift is detected in the knock sensor signal acquired during the combustion window, it is considered interfered with, and the knock detection result is deemed unreliable. Degradation control is implemented by correcting the ignition advance angle, enabling better engine knock protection even when knock sensor signals are interfered with and misjudgments are possible.

[0081] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for detecting the reliability of detonation signals, characterized in that, Includes the following steps: During the continuous non-combustion window and combustion window, the signal from the knock sensor is acquired, the background noise signal of the combustion window is extracted, and the signal corresponding to the set range before the top dead center of the cylinder compression in the non-combustion window is extracted, which is denoted as the Pre window signal. The Pre window signal is reliable, and after consistency calibration, if the difference between the weighted value of the background noise signal of the current cylinder combustion window and the background noise of other cylinder combustion windows exceeds the set threshold, the signal obtained by the knock sensor in the combustion window will drift. The Pre window signal is reliable, but it has not been calibrated for consistency. If the difference between the background noise signal of the current cylinder combustion window and the Pre window signal exceeds the set threshold, the signal obtained by the knock sensor in the combustion window will drift. The number of times the signal obtained by the knock sensor in the combustion window drifts exceeds the limit, and the corresponding knock judgment result is unreliable. The ignition advance angle is then corrected.

2. The method for detecting the reliability of detonation signals as described in claim 1, characterized in that, The ignition advance angle is corrected by using the knock back angle, where the knock back angle = correction coefficient x * average knock back angle of other cylinders + correction coefficient y * maximum knock back angle of other cylinders.

3. The method for detecting the reliability of detonation signals as described in claim 1, characterized in that, When the Pre window signal is unreliable, the ignition advance angle is corrected.

4. The method for detecting the reliability of detonation signals as described in claim 1, characterized in that, If the deviation between the acquired Pre window signal and the preset value does not exceed the set value, the Pre window signal is reliable; if the deviation exceeds the set value, the Pre window signal is unreliable.

5. The method for detecting the reliability of detonation signals as described in claim 1, characterized in that, If the Pre window signal is reliable and the engine has undergone consistency calibration, the difference between the weighted value of the background noise signal of the current cylinder combustion window and the Pre window signal of other cylinders exceeds the set threshold, and the signal obtained by the knock sensor in the combustion window drifts.

6. The method for detecting the reliability of detonation signals as described in claim 1, characterized in that, The combustion window is the time period from spark plug ignition to the end of combustion in the cylinder. During this time, the crankshaft rotates from x° to y°.

7. The method for detecting the reliability of detonation signals as described in claim 1, characterized in that, The non-combustion window is the set range before the cylinder compression top dead center, and the corresponding crankshaft angle range is z°-x°, where the crankshaft rotates to x° to correspond to the cylinder compression top dead center.

8. A detonation signal reliability detection system, characterized in that, include: The signal acquisition unit is connected to the knock sensor and is used to acquire the signal of the knock sensor during the continuous non-combustion window and combustion window, and extract the background noise signal of the combustion window, as well as the signal corresponding to the set range before the top dead center of the cylinder compression in the non-combustion window, which is denoted as the Pre window signal. The knock signal reliability detection unit is configured such that: if the Pre window signal is reliable and after consistency calibration, if the difference between the weighted value of the background noise signal of the current cylinder combustion window and the background noise of other cylinder combustion windows exceeds a set threshold, the signal obtained by the knock sensor in the combustion window will drift. The knock signal reliability detection unit is also configured such that: if the difference between the background noise signal of the current cylinder combustion window and the Pre window signal exceeds a set threshold when the Pre window signal is reliable but has not been calibrated, the signal obtained by the knock sensor in the combustion window will drift. The correction unit is configured to correct the ignition advance angle when the number of times the signal obtained by the knock sensor in the combustion window drifts exceeds the limit and the corresponding knock judgment result is unreliable.

9. An engine, characterized in that, It has a controller that performs the steps in the knock signal reliability detection method as described in any one of claims 1-7.

10. A motor vehicle, characterized in that, It has an on-board computer that performs the steps in the knock signal reliability detection method as described in any one of claims 1-7.

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