Method for sensing bearing damage of an engine

Abstract

The present application relates to a method for sensing bearing damage of an engine. The method for sensing bearing damage of an engine using a vibration signal can sense bearing damage for each driving state (acceleration driving, cruising driving, deceleration driving) of a vehicle using a frequency signal input to a knock sensor from an engine even without a sensor directly sensing bearing damage.

Description

Technical Field

[0001] This invention relates to a method for sensing bearing damage in a vehicle engine. Background Technology

[0002] The statements in this section are merely background information in relation to the invention and may not constitute prior art.

[0003] In the vehicle's engine, the crankshaft 12 is connected to the cylinder block, and the connecting rod 11 is fitted with a bearing 13 to reduce friction.

[0004] Figure 1 A portion of the connection between connecting rod 11 and crankshaft 12 is shown. The large end of connecting rod 11 is fastened to surround crank pin 12b in crankshaft 12, and a bearing 13 is disposed between the large end of connecting rod 11 and crank pin 12b. Crankshaft 12 is supported by cylinder block via crank journal 12a, and the small end of connecting rod 11 is connected to piston 14. Furthermore, oil is filled between the large end of connecting rod 11 and crank pin 12b to reduce friction between them during operation. Under normal conditions, the clearance between bearing 13 and crank pin 12b is small, and an oil layer forms between them, resulting in less noise and vibration.

[0005] Meanwhile, when the engine operates for an extended period with foreign objects introduced into the section where the bearing 13 is mounted, or with machining defects (e.g., machining defects in the connecting rod journal) occurring in the bearing 13 or the section in contact with the bearing 13, the bearing 13 wears and is damaged. When this condition persists, the clearance between the bearing 13 and the crank pin 12b becomes large, generating noise and vibration due to impact, and the bearing 13 and crank pin 12b become seized.

[0006] As described above, when the bearing 13 and crank pin 12b are stuck, the oil supply between the large end of the connecting rod 11 and the crank pin 12b stops, which can cause problems such as vehicle stalling or engine damage.

[0007] Typically, in order to detect bearing damage, a technique has been used that utilizes a sensor that senses engine vibration (i.e., a knock sensor) to detect bearing damage.

[0008] However, we found that the engine vibration signal measured by the knock sensor should be divided into a knock signal and a bearing damage signal, and processed by the vehicle's engine control unit (ECU). However, if the ECU can only process one signal, there is a problem where the ECU cannot be applied. To solve this problem, the vehicle's ECU should be replaced with a new ECU capable of processing both signals, or a separate bearing damage sensing kit should be applied. New ECUs are easily applied to vehicles under development, but applying them to mass-produced vehicles operated by consumers is not easy. Because the hardware specifications of ECUs in mass-produced vehicles are lower, they cannot apply new logic; therefore, the ECUs in vehicles under development should be replaced by developing and producing new ECUs.

[0009] In addition, using individual kits may cause unexpected side effects.

[0010] Furthermore, the application of all new ECUs and individual kits inevitably incurs significant costs. Summary of the Invention

[0011] The present invention provides a method for sensing bearing damage in an engine, which can use a vibration signal received from a vibration sensor (knock sensor) of the engine to sense the bearing damage.

[0012] In one embodiment of the present invention, a method for sensing bearing damage in an engine includes: a driving state determination step, wherein a controller for controlling the engine determines whether the vehicle is accelerating or decelerating; an acceleration diagnostic step, wherein when the vehicle accelerates, the controller distinguishes between signals generated by combustion knock and signals generated by the damaged bearing from signals sensed by a knock sensor within a combustion knock monitoring band, and when bearing damage is determined based on the signal generated by the damaged bearing, the controller increments an acceleration diagnostic counter; a deceleration diagnostic step, wherein when the vehicle decelerates, the controller increments a deceleration diagnostic counter when a signal generated by the damaged bearing is sensed by a knock sensor within a bearing damage monitoring band; a damage determination step, wherein the controller compares the acceleration diagnostic counter and the deceleration diagnostic counter with a bearing damage benchmark to confirm bearing damage; and a bearing damage confirmation step, wherein when the acceleration diagnostic counter and the deceleration diagnostic counter are above the bearing damage benchmark, the controller confirms bearing damage.

[0013] When the accelerator pedal is pressed, the driving status determination step determines that the vehicle is accelerating; when the accelerator pedal is not pressed, the driving status determination step determines that the vehicle is decelerating.

[0014] The combustion detonation monitoring frequency band is from 10kHz to 18kHz, and the bearing damage monitoring frequency band is from 1kHz to 8kHz.

[0015] The acceleration diagnostic steps include: an acceleration frequency monitoring step, wherein the controller monitors the engine vibration signal sensed by the knock sensor in the combustion knock monitoring frequency band; an acceleration diagnostic entry determination step, wherein during acceleration, the controller determines whether the time for which the knock sensor value exceeds a first reference value for initiating bearing damage diagnosis is greater than or equal to a preset first reference time; an acceleration damage determination step, wherein during acceleration, when the time for which the knock sensor value exceeds the first reference value is greater than or equal to the preset first reference time, the controller determines whether the time for which the knock sensor value exceeds a second reference value for determining bearing damage is greater than or equal to a preset second reference time; and an acceleration diagnostic counter increment step, wherein when the time for which the knock sensor value exceeds the second reference value is greater than or equal to the preset second reference time, the controller increments the acceleration diagnostic counter to determine bearing damage during acceleration.

[0016] The second reference value is set to be greater than the first reference value.

[0017] The first reference time and the second reference time are set to the engine's rotation cycle.

[0018] In the damage determination step during acceleration, the sensor value of the knock sensor is a moving average.

[0019] During the acceleration diagnostic entry determination step, if the knock sensor value does not exceed the first reference value, or during the acceleration damage determination step, if the knock sensor value does not exceed the second reference value, one of the steps of the driving status determination step and the acceleration diagnostic entry determination step is executed again.

[0020] The deceleration diagnostic steps include: a deceleration frequency monitoring step, wherein the controller monitors the engine vibration signal sensed by the knock sensor in the bearing damage monitoring frequency band; a deceleration diagnostic entry determination step, wherein the controller determines whether the knock sensor value exceeds a third reference value for starting bearing damage diagnosis during deceleration, and whether the time for which the knock sensor value exceeds the third reference value is greater than or equal to a third reference time for starting bearing damage diagnosis during deceleration; a deceleration damage determination step, wherein when the knock sensor value exceeds the third reference value and the time for which the knock sensor value exceeds the third reference value is greater than or equal to a third reference time, the controller determines whether the knock sensor value exceeds a fourth reference value, the fourth reference value being a reference value used to determine bearing damage; and a deceleration diagnostic counter increment step, wherein when the knock sensor value exceeds the fourth reference value, the controller increments the deceleration diagnostic counter to determine bearing damage during deceleration.

[0021] During the deceleration diagnostic entry determination step, if the knock sensor value does not exceed the third reference value, or even if the knock sensor value exceeds the third reference value but the time for which the knock sensor value exceeds the third reference value is less than the third reference time, one of the steps in the driving state determination step and the deceleration diagnostic entry determination step is executed again.

[0022] In the damage determination step during deceleration, if the sensor value of the knock sensor does not exceed the fourth reference value, one of the steps in the driving status determination step and the deceleration diagnosis entry determination step is executed again.

[0023] The bearing damage confirmation steps involve confirming whether the diagnostic counters during acceleration and deceleration are both above "1".

[0024] Prior to the driving status determination step, the method for sensing bearing damage in the engine further includes a diagnostic start determination step, wherein it is determined whether the engine or vehicle is in a state for sensing bearing damage, wherein the diagnostic start determination step determines whether the temperature of the engine oil is higher than a preset diagnostic start temperature.

[0025] After the bearing damage confirmation step, the limp home mode step is executed, in which the engine speed per minute (RPM) is limited to below the preset maximum safe engine RPM.

[0026] After the bearing damage confirmation step, the warning device operation step is performed, wherein when the bearing is damaged, the warning device installed in the vehicle is operated to warn the passengers of the bearing damage.

[0027] Meanwhile, in order to achieve the objective, the method for sensing bearing damage of an engine according to the present invention includes the following steps: a driving state determination step, wherein a controller for controlling the engine determines whether the vehicle is accelerating; an acceleration frequency monitoring step, wherein when the vehicle is accelerating, the controller monitors the vibration signal of the engine sensed by the knock sensor in the combustion knock monitoring frequency band; an acceleration diagnosis entry determination step, wherein when accelerating, it is determined whether the time during which the sensor value of the knock sensor exceeds a first reference value for starting the diagnosis of bearing damage is greater than a preset first reference time; during acceleration... The damage determination step includes the following steps: During acceleration, if the time for which the knock sensor value exceeds a first reference value is greater than or equal to a preset first reference time, determine whether the time for which the knock sensor value exceeds a second reference value for determining bearing damage is greater than or equal to a preset second reference time; During acceleration, a diagnostic counter increment step is performed, where, if the time for which the knock sensor value exceeds the second reference value is greater than or equal to a preset second reference time, the acceleration diagnostic counter is incremented to determine bearing damage during acceleration; During the damage determination step, the controller compares the acceleration diagnostic counter with a bearing damage benchmark to confirm bearing damage; During the bearing damage confirmation step, if the acceleration diagnostic counter exceeds the bearing damage benchmark, the controller confirms bearing damage.

[0028] After the bearing damage confirmation step, the limp home mode step is executed, in which the engine RPM is limited to below the preset maximum safe engine RPM.

[0029] After the bearing damage confirmation step, the warning device operation step is performed, wherein when the bearing is damaged, the warning device installed inside the vehicle is operated to warn the passengers of the bearing damage.

[0030] Furthermore, in order to achieve the objective, the method for sensing bearing damage of an engine according to the present invention includes the following steps: a driving state determination step, wherein a controller for controlling the engine determines whether the vehicle is decelerating; a deceleration frequency monitoring step, wherein when the vehicle is determined to be decelerating in the driving state determination step, the controller monitors the vibration signal of the engine sensed by the knock sensor in the bearing damage monitoring frequency band; and a deceleration diagnosis entry determination step, wherein when deceleration occurs, it is determined whether the sensor value of the knock sensor exceeds a third reference value for initiating the diagnosis of bearing damage, and the time during which the sensor value of the knock sensor exceeds the third reference value. The steps include: a damage determination step during deceleration, where if the knock sensor value exceeds the third reference value and the time for which the knock sensor value exceeds the third reference value is greater than the third reference time, it is determined whether the knock sensor value exceeds a fourth reference value, which is a reference value used to determine bearing damage; a deceleration diagnostic counter increment step, where if the knock sensor value exceeds the fourth reference value, the deceleration diagnostic counter is incremented to determine bearing damage during deceleration; a damage determination step, where the controller compares the deceleration diagnostic counter with a bearing damage benchmark to confirm bearing damage; and a bearing damage confirmation step, where the controller confirms bearing damage if the deceleration diagnostic counter is greater than or equal to the bearing damage benchmark.

[0031] After the bearing damage confirmation step, the limp home mode step is executed, in which the engine RPM is limited to below the preset maximum safe engine RPM.

[0032] After the bearing damage confirmation step, the warning device operation step is performed, wherein when the bearing is damaged, the warning device installed in the vehicle is operated to warn the passengers of the bearing damage.

[0033] The method for sensing bearing damage in an engine according to the present invention, with the above configuration, can sense bearing damage using only a vibration signal acquired by a knock sensor installed in the engine.

[0034] Depending on whether combustion knock is diagnosed based on vehicle driving conditions, the accuracy of bearing damage sensing can be improved by varying the frequency in the non-knock range. Furthermore, by maintaining the traditional diagnostic frequency in the knock-diagnosed range, but utilizing the characteristic differences between combustion knock and bearing damage signals to distinguish between combustion knock and bearing damage, it is possible to prevent incorrect diagnosis of combustion knock or impact vibration as bearing damage.

[0035] Furthermore, bearing damage can be detected simply by upgrading the software of the ECU in a running vehicle, without the need for a new ECU or a separate kit, thus saving costs.

[0036] Further applications will become apparent from the description provided herein. It should be understood that this specification and specific examples are for illustrative purposes only and are not intended to limit the scope of the invention. Attached Figure Description

[0037] To better understand the present invention, various embodiments of the invention will be described by way of example with reference to the accompanying drawings, in which:

[0038] Figure 1 This is a schematic diagram showing the state of bearing installation at the connection between the connecting rod and crank pin of the engine;

[0039] Figure 2 This is a block diagram illustrating a system for performing a method for sensing bearing damage in an engine according to an embodiment of the present invention;

[0040] Figure 3 This is a flowchart illustrating a method for sensing bearing damage in an engine according to another embodiment of the present invention;

[0041] Figure 4 This is a graph showing the vibration signal measured by the knock sensor in an engine with bearing damage;

[0042] Figure 5A and Figure 5B This is a graph showing the change in knock signal based on the engine condition in an engine with bearing damage, where... Figure 5A This is a graph showing the changes in sensor values ​​within the combustion knock monitoring frequency band. Figure 5B It is a graph showing the changes in sensor values ​​in the bearing damage monitoring band;

[0043] Figure 6A and 6B This is a schematic graph showing the change in the sensor value of the knock sensor during acceleration, where... Figure 6A This is a graph showing the change in sensor values ​​during excessive combustion and detonation. Figure 6B It is a graph showing the change in sensor values ​​when the bearing is damaged;

[0044] Figure 7A and 7B This is a graph illustrating the principle of determining bearing damage during acceleration, where... Figure 7A This is a graph showing the change in sensor values ​​during excessive combustion and detonation. Figure 7BIt is a graph showing the change in sensor values ​​when the bearing is damaged;

[0045] Figure 8A and 8B This is a graph illustrating the principle of determining bearing damage during deceleration, in which... Figure 8A This is a graph showing the change in sensor values ​​caused by a single detonation. Figure 8B This is a graph showing the change in sensor values ​​when the bearing is damaged.

[0046] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Detailed Implementation

[0047] The following description is merely exemplary in nature and is not intended to limit the invention, application, or use. It should be understood that in all the drawings, corresponding reference numerals denote the same or corresponding parts and features.

[0048] Hereinafter, a method for sensing bearing damage in an engine according to the present invention will be described in detail with reference to the accompanying drawings.

[0049] In one embodiment of the present invention, a method for sensing bearing damage in an engine utilizes vibration signals sensed by a knock sensor 15 installed in an engine 10 of a vehicle to sense damage to a bearing 13 installed in the engine. Specifically, the method includes: a driving state determination step (S120), in which a controller 20 for controlling the engine 10 determines whether the vehicle is accelerating or decelerating; an acceleration diagnostic step (S200), in which, when bearing 13 damage is determined by distinguishing a combustion knock signal and a bearing 13 damage signal from signals sensed by the knock sensor 15 in the combustion knock monitoring band (F_A) during acceleration, the controller 20 increments the acceleration diagnostic counter (C1); and a deceleration diagnostic step (S300), in which, when bearing damage is detected in the bearing damage monitoring band (F_B) during deceleration... When a damage signal of bearing 13 is sensed from the signal sensed by knock sensor 15, controller 20 increases the deceleration diagnostic counter (C2); in the damage determination step (S410), controller 20 compares the acceleration diagnostic counter (C1) and deceleration diagnostic counter (C2) with the bearing damage reference (C) used to confirm the damage of bearing 13; in the bearing damage confirmation step (S420), when the acceleration diagnostic counter (C1) and deceleration diagnostic counter (C2) are above the bearing damage reference (C), controller 20 confirms the damage of bearing 13.

[0050] First, a system for performing the method for sensing bearing damage in an engine according to the present invention is described, such as... Figure 2As shown, the system includes a knock sensor 15 and a controller 20. The knock sensor 15 is an example of a vibration sensing device mounted on one side of the engine 10 to measure vibrations transmitted from the engine 10 and thus sense knocking of the engine 10. The controller 20 is used to control the operation of the engine 10 and identify vibration signals generated by the engine 10 to determine if the bearing 13 is damaged.

[0051] The method for sensing bearing damage in the engine, which will be described later, is stored in the controller 20 as logic for sensing damage to bearing 13. Hereinafter, the ECU will be described as controller 20 as an example.

[0052] The method for sensing bearing damage in an engine according to the present invention is applied to a situation where the controller 20 (i.e., the engine control unit (ECU)) can only process a single frequency signal.

[0053] The ECU 20 determines the vehicle's driving status and, regarding combustion knock and bearing damage, uses signals in the frequency band that detects combustion knock during acceleration and signals in the frequency band that effectively diagnoses bearing damage during deceleration.

[0054] Figure 4 The signal detected by the knock sensor 15 in the engine 10 with bearing damage is shown.

[0055] During acceleration, signals from the frequency band (F_A) used to detect combustion knock are utilized. During acceleration, combustion knock in the engine 10 should be detected, and signals from the frequency band used to detect combustion knock (i.e., the combustion knock monitoring frequency band (F_A)) are used to determine whether the signal sensed by the knock sensor 15 is caused by combustion knock or bearing damage, thereby detecting bearing 13 damage. Typically, the combustion knock monitoring frequency band (F_A) is 10kHz to 18kHz.

[0056] Furthermore, during deceleration, engine 10 does not burn, therefore there is no need to sense combustion knock, and the signal in the frequency band (F_B) that is well-suited for diagnosing bearing damage can be utilized. When bearing 13 is damaged, a signal for bearing 13 damage is generated across the entire frequency band, but using a different frequency band than the combustion knock signal. Typically, the bearing damage monitoring frequency band (F_B) is from 1 kHz to 8 kHz. Figure 5A and Figure 5B As shown, in an engine with bearing damage, the frequency band is changed so that when the operating state of engine 10 changes from partial load (PL) to deceleration state without fuel cut-off (PU), the bearing damage can be better diagnosed.

[0057] Based on the engine 10 within the aforementioned frequency band, the combustion knock monitoring frequency band (F_A) and bearing damage monitoring frequency band (F_B) can be determined and used as a narrower frequency band within the aforementioned range.

[0058] For example, the combustion knock monitoring band (F_A) can utilize signals from the 11kHz or 15kHz frequency band, while the bearing damage monitoring band (F_B) can utilize signals from the 6kHz frequency band.

[0059] If, due to hardware limitations, ECU 20 can only process one frequency signal, then even without replacing ECU 20 or adding a separate kit capable of processing that additional frequency signal, ECU 20 can still have diagnostic capabilities such as being able to process multiple frequency signals.

[0060] The diagnostic start determination step (S110) determines whether the engine 10 or vehicle is in a state where damage to the bearing 13 is being sensed. Since this invention uses the vibration generated by the engine 10 during engine operation to sense damage to the bearing 13, the diagnostic start determination step (S110) determines whether the engine 10 is sufficiently preheated and whether the vibration signal of the engine 10 is stable, and then begins the diagnosis of the bearing 13. Before the engine 10 is preheated, noise is generated due to friction from various instruments, so the damage to the bearing 13 cannot be accurately determined. Therefore, the diagnostic start determination step (S110) determines whether the engine 10 is preheated and diagnoses the damage to the bearing 13 while the engine is preheated. Simultaneously, the vibration of the engine 10 is used to diagnose the state of the engine 10; therefore, this invention determines whether the engine is preheated by the temperature of the engine oil measured by the oil temperature sensor 16, rather than the temperature of the coolant. When the temperature of the engine oil (T_oil) is higher than a preset diagnostic start temperature (T_THD) (T_oil > T_THD), the diagnosis of damage to the bearing 13 can begin. Here, the diagnostic start temperature (T_THD) can be set to 80°C.

[0061] The driving state determination step (S120) determines the operating state of the engine 10 by whether the accelerator pedal 31 is operated. According to one embodiment of the invention, the ECU 20 wishes to receive and process a signal from the knock sensor 15, thereby changing the frequency according to the operating state of the engine 10, so that the operating state of the engine 10 is determined by the accelerator pedal 31.

[0062] Based on the determination result of the driving state determination step (S120), execute either the acceleration diagnosis step (S200) or the deceleration diagnosis step (S300) that will be described later.

[0063] For example, during deceleration without operating the accelerator pedal 31 (pedal value = 0), the engine 10 does not burn, therefore there is no need to diagnose combustion knocking in the engine 10. This allows the frequency band to be changed to one that can effectively diagnose damage to the bearing 13, i.e., the bearing damage monitoring frequency band (F_B). Typically, the bearing damage monitoring frequency band (F_B) can be from 1 kHz to 8 kHz.

[0064] Furthermore, when the accelerator pedal 31 is operated (ped value > 0), i.e., during acceleration or cruising, it is desirable to diagnose engine combustion knock, thereby maintaining the conventional frequency band used for diagnosing combustion knock frequencies, i.e., the combustion knock monitoring frequency band (F_A). Typically, the combustion knock monitoring frequency band (F_A) is 10kHz to 18kHz.

[0065] The acceleration diagnostic step (S200) determines damage to the bearing 13 during vehicle acceleration (including cruising). During acceleration, an engine knock signal is generated in the engine 10, thereby determining whether the sensor value output by the knock sensor 15 is caused by combustion knock or by damage to the bearing 13.

[0066] Since the present invention uses a sensor value output by the knock sensor 15 to sense the damage to the bearing 13, the present invention monitors the signal in the frequency band used to sense combustion knock during acceleration through the acceleration diagnostic step (S200), and distinguishes whether the abnormal signal sensed by the knock sensor 15 is generated by combustion knock or by the damage to the bearing 13, so as to sense the damage to the bearing 13.

[0067] However, the accelerated diagnostic step (S200) does not confirm the damage to bearing 13, but instead increments a counter used to confirm the damage to bearing 13, namely, the accelerated diagnostic counter (C1). The final confirmation of the damage to bearing 13 is then determined by the bearing damage confirmation step (S420) described later.

[0068] During acceleration, the frequency monitoring step (S210) involves the ECU 20 continuously receiving and monitoring signals from the combustion knock monitoring frequency band (F_A) of the knock sensor 15. When an abnormal signal is detected in the signal output from the knock sensor 15, the controller 20 determines whether the abnormal signal is caused by combustion knock or by damage to the bearing 13.

[0069] During acceleration, the diagnostic process proceeds to the determination step (S220), where the ECU 20 determines whether the signal input from the knock sensor 15 exceeds the first reference value (TH1) in the combustion knock monitoring band (F_A) to determine whether the bearing 13 is damaged during acceleration. The first reference value (TH1) serves as the benchmark for initiating the diagnosis of damage to the bearing 13 during acceleration.

[0070] When the vehicle accelerates, if the engine 10 is running normally, that is, if there is no combustion knock and the bearing 13 is not damaged, the sensor value of the knock sensor 15 is below the first reference value (TH1).

[0071] Furthermore, during acceleration, the diagnostic process enters a determination step (S220) to determine whether the sensor value of the knock sensor 15 exceeds a first reference value (TH1) and whether the duration exceeds a first reference time (P1). Here, the first reference time (P1) is set to the rotation cycle of the engine 10, and the first reference time (P1) can be 40 cycles.

[0072] For example, when the first reference value (TH1) is set to 3V, and the sensor value of the knock sensor 15 is above 3V and maintained for 40 cycles, the diagnosis of damage to the bearing 13 begins during acceleration.

[0073] If combustion knocking occurs, the sensor value of knock sensor 15 will intermittently exceed the first reference value (TH1), and this does not happen in every cycle, resulting in very large signal fluctuations (see [link]). Figure 6A Some sensor values ​​for the knock signal also exceeded the second reference value (TH2) used to confirm damage to bearing 13, but this phenomenon no longer persisted during combustion knock, and the sensor values ​​were lower than the first reference value (TH1) and the second reference value (TH2).

[0074] However, if bearing 13 is damaged, an abnormal signal will be generated in each cycle due to the increased clearance of the rotating components. As a result, the sensor value of knock sensor 15 will remain above the first reference value (TH1) and will also exceed the first reference time (P1) (see...). Figure 6B Furthermore, states exceeding the second reference value (TH2) frequently occur and persist for several cycles.

[0075] Therefore, during acceleration, the diagnostic process enters the determination step (S220) to determine the time when the sensor value of the knock sensor 15 exceeds the first reference value (TH1), and continuously determines whether damage to the bearing 13 is sensed during acceleration.

[0076] In the acceleration diagnostic entry determination step (S220), if the signal input from the knock sensor 15 does not exceed the first reference value (TH1), the acceleration diagnostic entry determination step (S220) is repeated.

[0077] When the signal input from the knock sensor 15 exceeds the first reference value (TH1) in the acceleration diagnostic entry determination step (S220), the acceleration damage determination step (S230) determines by the ECU 20 whether the signal input from the knock sensor 15 exceeds the second reference value (TH2) in the combustion knock monitoring frequency band, so as to determine whether the bearing 13 is damaged.

[0078] Here, the instantaneous sensor value of the knock sensor 15 can be used directly, or the moving average value of the knock sensor 15 can be used. Since the damage to the bearing 13 is determined by using the moving average value (which is the average value obtained by accumulating the sensor values ​​measured by the knock sensor 15 over a predetermined period of time), it helps to determine whether the transient fluctuations in the sensor value are caused by transient anomalies or by non-transient factors such as damage to the bearing 13.

[0079] Furthermore, the second reference value (TH2) is set higher than the first reference value (TH1). For example, when the first reference value (TH1) measured by the knock sensor 15 is 3.0V, the second reference value (TH2) is 4.8V.

[0080] The damage determination step during acceleration (S230) compares whether the sensor value of the knock sensor 15 exceeds the second reference value (TH2) and the time for which the sensor value of the knock sensor 15 exceeds the second reference value (TH2). Here, the second reference value (TH2) can be 100 cycles.

[0081] For example, when the sensor value of the knock sensor 15 exceeds the second reference value (TH2) and the time for which the sensor value of the knock sensor 15 exceeds the second reference value (TH2) exceeds the second reference time (P2), the acceleration damage determination step (S230) determines that the bearing 13 is damaged. That is, as Figure 7B As shown, when the sensor value of the knock sensor 15 exceeds the first reference value (TH1) and the time for which the sensor value of the knock sensor 15 exceeds the first reference value (TH1) exceeds the first reference time (P1), the acceleration damage determination step (S230) determines whether the moving average value of the knock sensor 15 exceeds the second reference value (TH2) and whether the time for which the moving average value of the knock sensor 15 exceeds the second reference value (TH2) exceeds the second reference time (P2) to confirm damage to the bearing 13. Here, the second reference time (P2) is set to the rotation cycle of the engine 10, and the second reference time can be 100 cycles. The first reference time (P1) and the second reference time (P2) are set to the rotation cycle of the engine 10 that can accurately diagnose damage to the bearing 13 without misdiagnosis.

[0082] When the sensor value of the knock sensor 15 exceeds the second reference value (TH2) and the time for which the sensor value of the knock sensor 15 exceeds the second reference value (TH2) exceeds the second reference time (P2), the acceleration time diagnostic counter increment step (S240) described later is executed.

[0083] If the conditions are not met in the accelerated damage determination step (S230), the step returns to the accelerated diagnostic entry determination step (S220).

[0084] For example, even if the sensor value of the knock sensor 15 is less than the second reference value (TH2) or the sensor value of the knock sensor 15 exceeds the second reference value (TH2), when the time during which the sensor value of the knock sensor 15 is less than the second reference value (TH2) or the time during which the sensor value of the knock sensor 15 exceeds the second reference value (TH2) is less than the second reference time (P2) (see [reference]). Figure 7A It was also determined to be combustion detonation.

[0085] Meanwhile, if these conditions are not met in the acceleration diagnosis determination step (S220) and the acceleration damage determination step (S230), the step returns to the driving state determination step (S120). If the driving state changes, the damage to the bearing 13 can be sensed again accordingly.

[0086] If the acceleration damage determination step (S230) determines that the bearing 13 is damaged, the acceleration diagnostic counter increment step (S240) increments the acceleration diagnostic counter (C1) that counts the damage to the bearing 13. When the sensor value of the knock sensor 15 exceeds the second reference value (TH2) in the acceleration damage determination step (S230) and the time for which the sensor value of the knock sensor 15 exceeds the second reference value (TH2) exceeds the second reference time (P2), the acceleration diagnostic counter increment step (S240) increments the acceleration diagnostic counter (C1).

[0087] When damage to bearing 13 is confirmed during vehicle acceleration or cruising, controller 20 increments and accumulates the acceleration diagnostic counter (C1).

[0088] The deceleration diagnostic step (S300) determines the damage to bearing 13 when the vehicle decelerates.

[0089] When the vehicle decelerates, the engine 10 does not burn and does not produce an engine knock signal. Therefore, since there is no need to diagnose combustion knock, the damage to the bearing 13 is determined by changing the frequency band sensed by the knock sensor 15 and processed by the controller 20 to a frequency band that can well diagnose bearing damage (i.e., the bearing damage monitoring frequency band (F_B)).

[0090] However, the damage to bearing 13 is not confirmed in the deceleration diagnostic step (S300). Instead, a counter for confirming the damage to bearing 13 is added, namely, the deceleration diagnostic counter (C2). The final confirmation of the damage to bearing 13 is determined by the bearing damage confirmation step (S420) described later.

[0091] During deceleration, the frequency monitoring step (S310) is continuously received and monitored by the ECU 20 from the knock sensor 15 for the bearing damage monitoring band (F_B) used to effectively sense damage to the bearing 13.

[0092] During deceleration, the diagnostic process enters a determination step (S320). The ECU 20 determines whether the signal input from the knock sensor 15 exceeds the third reference value (TH3) in the bearing damage monitoring band (F_B) to determine whether damage to the bearing 13 has been diagnosed during deceleration. The third reference value is the benchmark for starting to determine the damage to the bearing 13 during deceleration.

[0093] For example, when the third reference value (TH3) is set to 1.75V, and the sensor value of the knock sensor 15 is above 1.75V, the diagnosis of damage to the bearing 13 begins.

[0094] In addition, during deceleration, the diagnostic process enters a determination step (S320) to determine whether the sensor value of the knock sensor 15 exceeds the third reference value (TH3) and whether the time (P) when the sensor value exceeds the third reference value (TH3) is above the third reference time (P3) for starting the diagnosis of damage to the bearing 13.

[0095] For example, the third reference time (P3) is set to the rotation cycle of the engine 10. By setting the third reference time (P3) to 4 cycles, if the sensor value of the knock sensor 15 exceeds 1.75V for 4 cycles during deceleration, damage to the bearing 13 is detected.

[0096] During deceleration, the damage determination step (S330) involves the ECU 20 determining whether the signal input from the knock sensor 15 exceeds the fourth reference value (TH4) used to determine the damage of the bearing 13, in order to determine whether the bearing 13 is damaged.

[0097] During deceleration, a single impact vibration is caused, resulting in only a high peak value (the sensor value of the knock sensor usually does not exceed the third reference value, only the peak value exceeds the fourth reference value) when the sensor value of the knock sensor 15 is normally not high, and the duration (P) is short. However, when the bearing 13 is damaged, abnormal signals are continuously generated in the bearing damage monitoring band (F_B) to the extent that the damage to the bearing 13 is suspected (when the sensor value of the knock sensor exceeds the third reference value for the third reference time), and the peak value also exceeds the fourth reference value.

[0098] Therefore, damage to the bearing 13 is sensed during deceleration by determining whether the time (P) when the sensor value of the knock sensor 15 exceeds the third reference value (TH3) is greater than the third reference time (P3) in the deceleration diagnosis entry determination step (S320) and whether the knock signal exceeds the fourth reference value (TH4) in the deceleration damage determination step (S330).

[0099] like Figure 8A As shown, when the engine operating at partial load (PL) changes to a deceleration state without fuel cut-off (PU), the sensor value of knock sensor 15 exceeds the fourth reference value (TH4), but the duration (P) of maintaining this state is less than the third reference time (P3) and is temporary, therefore damage to bearing 13 cannot be diagnosed. However, as Figure 8B As shown, when an engine operating at partial load (PL) enters the PU state while simultaneously operating in the deceleration state with fuel cut-off (PUC) without fuel cut-off, if the time (P) during which the sensor value of the knock sensor 15 exceeds the third reference value (TH3) exceeds the third reference time (P3), and within that time, the sensor value of the knock sensor 15 exceeds the fourth reference value (TH4), then the bearing 13 is diagnosed as damaged.

[0100] That is, when the time (P) when the sensor value of the knock sensor 15 exceeds the third reference value (TH3) is greater than the third reference time (P3) and exceeds the fourth reference value (TH4) within that time (P), the bearing 13 is diagnosed as damaged.

[0101] As described above, when the sensor value of the knock sensor 15 exceeds the third reference value (TH3) and the time (P) exceeds the third reference time (P3), diagnosis begins (S320). When the sensor value of the knock sensor 15 exceeds the fourth reference value (TH4), damage is determined (S330), thereby diagnosing the damage to the bearing 13 during deceleration.

[0102] Meanwhile, if these conditions are not met in the deceleration diagnosis entry determination step (S320) and the deceleration damage determination step (S330), the step returns to the deceleration diagnosis entry determination step (S320).

[0103] Alternatively, if these conditions are not met in the deceleration diagnosis determination step (S320) and the deceleration damage determination step (S330), the step returns to the driving state determination step (S120), and if the driving state changes, the damage to the bearing 13 can be sensed again accordingly.

[0104] If damage to bearing 13 is determined in the damage determination step (S330) during deceleration, the deceleration diagnostic counter increment step (S340) increments the deceleration diagnostic counter (C2) to count the damage to bearing 13.

[0105] When damage to bearing 13 is confirmed while the vehicle is decelerating, controller 20 increments the deceleration diagnostic counter (C2) and performs an accumulation count.

[0106] The damage determination step (S410) determines whether the diagnostic counters (C1) during acceleration and (C2) during deceleration reach a predefined benchmark in order to determine whether the bearing 13 is damaged.

[0107] In order to determine whether the bearing 13 is damaged in the damage determination step (S410), when the diagnostic counter (C1) during acceleration and the diagnostic counter (C2) during deceleration reach the bearing damage benchmark (C) for confirming the damage of the bearing 13 (C1+C2=C), it is determined whether the bearing 13 is damaged.

[0108] Here, the diagnostic counter (C1) during acceleration and the diagnostic counter (C2) during deceleration are both above "1".

[0109] Damage to bearing 13 can be determined by comparing the sum of the diagnostic counters during acceleration (C1) and deceleration (C2) with the bearing damage reference (C). However, in this case, a false diagnosis may occur, resulting in the diagnostic counters during acceleration (C1) and deceleration (C2) both being "1" or higher.

[0110] That is, when the diagnostic counter (C1) reaches the predefined benchmark only during acceleration (diagnostic counter = 0 during deceleration) or when the diagnostic counter (C2) reaches the predefined benchmark only during deceleration (diagnostic counter = 0 during acceleration), it includes signals unrelated to the damage to bearing 13, which may lead to misdiagnosis.

[0111] On the other hand, when bearing 13 is damaged, abnormal signals will be generated during acceleration or deceleration, causing the diagnostic counter (C1) during acceleration and the diagnostic counter (C2) during deceleration to be above "1", thereby reducing false diagnosis.

[0112] Furthermore, the damage determination step (S410) determines whether the acceleration diagnostic counter (C1) and deceleration diagnostic counter (C2) have reached a reference within a predetermined number of accelerations. For example, when two acceleration diagnostic counters (C1) and one deceleration diagnostic counter (C2) are generated and accumulated under five acceleration conditions, this can be identified as damage to the bearing 13.

[0113] Of course, damage to bearing 13 can also be confirmed if only one of the acceleration diagnostic counter (C1) and deceleration diagnostic counter (C2) reaches a predetermined bearing damage benchmark (C) (C1 = C or C2 = C). For example, damage to bearing 13 can also be confirmed if either the acceleration diagnostic counter (C1) or the deceleration diagnostic counter (C2) exceeds "3".

[0114] Meanwhile, in the damage determination step (S410), when neither the diagnostic counter (C1) during acceleration nor the diagnostic counter (C2) during deceleration reaches the reference, the logic returns to the driving state determination step (S120), and each of the above steps is executed again.

[0115] In the damage determination step (S410), when the diagnostic counter (C1) during acceleration and the diagnostic counter (C2) during deceleration reach a predefined benchmark, the bearing damage confirmation step (S420) confirms the damage to the bearing 13 by the ECU 20.

[0116] In the bearing damage confirmation step (S420), when the ECU 20 confirms damage to the bearing 13, the limphome mode step (S430) limits the RPM of the engine 10 to below a preset maximum safe engine RPM. By limiting the RPM of the engine 10, further damage to the bearing 13 can be prevented, thus preventing the engine 10 from stopping and allowing the vehicle to be driven to a repairable location.

[0117] If it is confirmed that bearing 13 is damaged, the alarm device operation step (S440) activates the alarm device installed inside the vehicle, making it easy for passengers to become aware of the damage to bearing 13. For example, the warning light 41 installed on the vehicle's instrument cluster can be turned on, or a warning sound can be generated by a speaker installed inside the vehicle.

Claims

1. A method for sensing bearing damage in a vehicle engine, the method comprising: The driving status determination step involves the controller determining whether the vehicle is accelerating or decelerating. The acceleration diagnostic steps include the following: when the vehicle accelerates, the controller distinguishes between signals generated by combustion knock and signals generated by damaged bearings from signals sensed by the knock sensor within the combustion knock monitoring frequency band. When bearing damage is determined based on the signal generated by the damaged bearing, the controller increments the acceleration diagnostic counter. During deceleration, the diagnostic steps include the following: when the vehicle decelerates, if the knock sensor detects a signal generated by a damaged bearing in the bearing damage monitoring band, the controller increments the deceleration diagnostic counter. The damage determination step involves the controller comparing the diagnostic counters during acceleration and deceleration with a bearing damage benchmark to confirm bearing damage; and The bearing damage confirmation process includes a step where, when the diagnostic counters during acceleration and deceleration are greater than or equal to the bearing damage benchmark, the controller confirms bearing damage. The accelerated diagnostic step includes: The acceleration frequency monitoring step involves the controller monitoring the engine vibration signal sensed by the knock sensor within the combustion knock monitoring frequency band. During acceleration, the diagnostic process enters a determination step, wherein when the vehicle accelerates, the controller determines whether the time when the knock sensor value exceeds the first reference value for starting the diagnosis of bearing damage is greater than or equal to a preset first reference time. The damage determination step during acceleration includes, when the vehicle accelerates and the time for which the knock sensor value exceeds a first reference value is greater than or equal to a preset first reference time, the controller determines whether the time for which the knock sensor value exceeds a second reference value for determining bearing damage is greater than or equal to a preset second reference time; and The acceleration-time diagnostic counter increment step involves the controller incrementing the acceleration-time diagnostic counter when the time the knock sensor value exceeds the second reference value is greater than or equal to a preset second reference time, in order to determine bearing damage during acceleration. The deceleration diagnostic steps include: The frequency monitoring step during deceleration involves the controller monitoring the engine vibration signal sensed by the knock sensor within the bearing damage monitoring frequency band. During deceleration, the diagnostic process enters a determination step, in which the controller determines whether the sensor value of the knock sensor exceeds the third reference value for starting the diagnosis of bearing damage during deceleration, and whether the time for the sensor value of the knock sensor to exceed the third reference value is more than the third reference time for starting the diagnosis of bearing damage during deceleration. The damage determination step during deceleration includes a process where, when the sensor value of the knock sensor exceeds a third reference value and the time during which the sensor value of the knock sensor exceeds the third reference value is greater than a third reference time, the controller determines whether the sensor value of the knock sensor exceeds a fourth reference value, which is a reference value used to determine bearing damage. The deceleration diagnostic counter increments during deceleration. Specifically, when the sensor value of the knock sensor exceeds the fourth reference value, the controller increments the deceleration diagnostic counter to determine bearing damage during deceleration.

2. The method according to claim 1, wherein, When the accelerator pedal is operated, the driving state determination step determines that the vehicle is accelerating; when the accelerator pedal is not operated, the driving state determination step determines that the vehicle is decelerating.

3. The method according to claim 1, wherein, The combustion detonation monitoring frequency band is from 10kHz to 18kHz. The bearing damage monitoring frequency band is from 1 kHz to 8 kHz.

4. The method according to claim 1, wherein, The second reference value is set to be greater than the first reference value.

5. The method according to claim 1, wherein, The preset first reference time and the preset second reference time are set to the engine's rotation cycle.

6. The method according to claim 1, wherein, In the damage determination step during acceleration, the sensor value of the knock sensor is a moving average.

7. The method according to claim 1, wherein, During the acceleration diagnostic entry determination step, if the knock sensor value does not exceed the first reference value, or during the acceleration damage determination step, if the knock sensor value does not exceed the second reference value, one of the steps of the driving status determination step and the acceleration diagnostic entry determination step is executed again.

8. The method according to claim 1, wherein, The fourth reference value is set to be greater than the third reference value.

9. The method according to claim 1, wherein, The third reference time is set to the engine's rotation cycle.

10. The method according to claim 1, wherein, During the deceleration diagnostic entry determination step, if the knock sensor value does not exceed the third reference value, or even if the knock sensor value exceeds the third reference value but the time for which the knock sensor value exceeds the third reference value is less than the third reference time, one of the steps in the driving state determination step and the deceleration diagnostic entry determination step is executed again.

11. The method according to claim 1, wherein, In the damage determination step during deceleration, if the sensor value of the knock sensor does not exceed the fourth reference value, one of the steps in the driving status determination step and the deceleration diagnosis entry determination step is executed again.

12. The method according to claim 1, wherein, The bearing damage confirmation step confirms whether the diagnostic counter during acceleration and the diagnostic counter during deceleration are both above "1".

13. The method of claim 1, further comprising: Before the driving condition determination step, a diagnostic start determination step is performed, which determines whether the engine or vehicle is in a state suitable for sensing bearing damage. The diagnostic start determination step determines whether the temperature of the engine oil is greater than a preset diagnostic start temperature.

14. The method of claim 1, further comprising: After the bearing damage confirmation step, the limp home mode step is executed, in which the engine speed is limited to below the preset maximum safe engine speed.

15. The method of claim 1, further comprising: After the bearing damage confirmation step, the warning device operation step is performed, wherein when the bearing is damaged, the warning device installed in the vehicle is operated to warn the passengers of the bearing damage.

16. A method for sensing bearing damage in a vehicle engine, the method comprising: The driving status determination step includes determining whether the vehicle is accelerating by the controller; The acceleration frequency monitoring step involves the controller monitoring the engine vibration signal sensed by the knock sensor in the combustion knock monitoring frequency band when the vehicle accelerates. During acceleration, the diagnostic process enters a determination step, wherein, during acceleration, it is determined whether the time during which the knock sensor value exceeds the first reference value for starting the diagnosis of bearing damage is greater than a preset first reference time. The damage determination step during acceleration includes, during acceleration, when the time when the sensor value of the knock sensor exceeds the first reference value is greater than or equal to the preset first reference time, determining whether the time when the sensor value of the knock sensor exceeds the second reference value for determining bearing damage is greater than or equal to the preset second reference time. The acceleration diagnostic counter increment step involves incrementing the acceleration diagnostic counter when the time for which the sensor value of the knock sensor exceeds the second reference value is greater than or equal to a preset second reference time, so as to determine bearing damage during acceleration. The damage determination step involves the controller comparing an acceleration-time diagnostic counter with a bearing damage benchmark to confirm bearing damage; and The bearing damage confirmation process includes a step where, during acceleration, if the diagnostic counter exceeds the bearing damage baseline, the controller confirms the bearing damage.

17. The method of claim 16, further comprising: After the bearing damage confirmation step, the limp home mode step is executed, in which the engine speed is limited to below the preset maximum safe engine speed.

18. The method of claim 16, further comprising: After the bearing damage confirmation step, the warning device operation step is performed, wherein when the bearing is damaged, the warning device installed in the vehicle is operated to warn the passengers of the bearing damage.

19. A method for sensing bearing damage in an engine, the method utilizing vibration signals sensed by a knock sensor mounted on the engine of a vehicle to sense damage to the bearing mounted on the engine, the method comprising: The driving status determination step includes determining whether the vehicle is decelerating by a controller used to control the engine; The frequency monitoring step during deceleration includes, when it is determined in the driving state determination step that the vehicle is decelerating, the controller monitors the vibration signal of the engine sensed by the knock sensor in the bearing damage monitoring frequency band. During deceleration, the diagnostic process enters a determination step, wherein, during deceleration, it is determined whether the sensor value of the knock sensor exceeds the third reference value at which the diagnosis of bearing damage begins, and whether the time at which the sensor value of the knock sensor exceeds the third reference value is more than the third reference time at which the diagnosis of bearing damage begins. The damage determination step during deceleration includes determining whether the sensor value of the knock sensor exceeds a third reference value and the time for which the sensor value of the knock sensor exceeds the third reference value is more than a third reference time. The fourth reference value is a reference value used to determine bearing damage. The diagnostic counter increments during deceleration, wherein when the sensor value of the knock sensor exceeds the fourth reference value, the diagnostic counter is incremented during deceleration to determine bearing damage during deceleration; The damage determination step includes, in which the controller compares a diagnostic counter during deceleration with a bearing damage benchmark to confirm bearing damage; and The bearing damage confirmation process includes a step where, during deceleration, if the diagnostic counter reading exceeds the bearing damage baseline, the controller confirms the bearing damage.

20. The method of claim 19, further comprising: After the bearing damage confirmation step, the limp home mode step is executed, in which the engine speed is limited to below the preset maximum safe engine speed.

21. The method of claim 19, further comprising: After the bearing damage confirmation step, the warning device operation step is performed, wherein when the bearing is damaged, the warning device installed in the vehicle is operated to warn the passengers of the bearing damage.

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