Method for detecting a damaged bearing of an internal combustion engine using a vibration signal

Abstract

A method for detecting damage to a motor bearing using a vibration signal, comprising: Separating (S120) a vibration signal from the engine, which is detected by a vibration sensor installed on the engine side of a vehicle, into a vibration signal due to combustion knock and into a vibration signal from a bearing installed between a crankpin and a connecting rod, Extracting (S130), through a signal processing filter, a signal in a predetermined natural frequency band from the vibration signal of the bearing, Determine (S140), in a predetermined engine operating condition, whether the bearing vibration signal is greater than a predetermined bearing failure threshold in order to detect bearing damage during engine operation, and Confirm (S160) that the bearing is damaged, where the vibration signal of the bearing is distinguishable from the vibration signal caused by combustion knocking based on the predetermined engine operating condition or a rotation angle of a crankshaft.

Description

Technical field

[0001] The present invention relates to a method for detecting a damaged bearing of an internal combustion engine using a vibration signal, which can process a vibration signal emanating from an internal combustion engine mounted on a vehicle, even without a sensor for directly detecting damage to a bearing, thereby detecting the damage to the bearing. background

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

[0003] In a vehicle's internal combustion engine, numerous parts are operated in a state in which they are coupled together, and a bearing is attached to a section to which each part is coupled in order to operate with reduced friction.

[0004] Fig. Figure 1 shows a section where a connecting rod 11 (e.g., a connecting rod) and a crankshaft are coupled together. A large-end section of the connecting rod 11 is attached to surround a crankpin 12b on the crankshaft, and a bearing 13 is provided between the large-end section of the connecting rod 11 and the crankpin 12b. The crankshaft is supported on a cylinder head by a crankshaft bearing 12a, and the small-end section of the connecting rod 11 is connected to a piston 14. Furthermore, oil is present between the large-end section of the connecting rod 11 and the crankpin 12b to reduce friction between the large-end section of the connecting rod 11 and the crankpin 12b during operation. In a normal condition (see Figure 1), the large-end section of the connecting rod 11 is lubricated by a bearing 13. Fig. 1) The gap between the bearing 13 and the crankpin 12b is small and an oil film is formed between them, so that noise and vibrations are low.

[0005] However, if, in the event that the internal combustion engine is subject to an abnormal condition for long-term durability (e.g., ingress of foreign material, oil shortage, poor workmanship of the connecting rod bearing, etc.) (see Fig. 2) If the internal combustion engine is operated continuously in a condition in which the bearing 13 is worn or damaged, a gap G between the bearing 13 and the crankpin 12b will increase and noise and vibrations will occur due to the impact of the connecting rod 11 and the crankshaft assembly 12b during operation of the internal combustion engine.

[0006] If the above condition continues to be maintained, as described in the Fig. As shown in Figure 3, bearing 13 can seize or bind on the crankpin 12b, thus interrupting the oil supply between the large end section of connecting rod 11 and the crankpin 12b. As described above, if the internal combustion engine is operated in a condition where bearing 13 in connecting rod 11 is damaged, the binding and metal-to-metal contact between bearing 13 and the large end section of connecting rod 11 will progress, resulting in noise and vibration outside the normal range. Furthermore, bearing 13 may be damaged (e.g., break).

[0007] If bearing 13 is damaged, frictional resistance causes the vehicle's internal combustion engine to stall or experience a loss of power. Specifically, if bearing 13 is damaged, the engine's power output is reduced due to an increase in frictional resistance. To compensate, the engine speed is increased when the accelerator pedal is pressed. However, increasing the engine speed causes the damaging process to repeat itself, further increasing the frictional resistance of the section where bearing 13 is installed. At this point, the temperature of the friction section rises due to the increased frictional resistance, accelerating the seizing process. As the temperature of bearing 13 increases, this damage also affects the parts adjacent to bearing 13, namely the connecting rod 11 and the crankpin 12b.

[0008] As described above, if bearing 13 seizes, this causes an overall problem with the internal combustion engine, resulting in the engine stalling or losing power, and this cannot be easily solved by repairing or replacing a part; the entire internal combustion engine must be repaired or replaced.

[0009] For example, each of US 2008 / 0 223 135 A1, KR 10 1 482 509 B1, JP 2009 030 470 A, DE 10 2013 222 545 A1 discloses a method for detecting bearing damage in motors and / or machines, in which vibrations are measured and the received signals are subjected to signal processing with filtering and indications of bearing damage are extracted from the filtered signals. In KR 10 1 482 509 B1, a vibration signal from a machine bearing is used; in US 2008 / 0 223 135 A1, a vibration signal from a shaft is used; and in JP 2009 030 470 A and DE 10 2013 222 545 A1, a knock signal from a knock sensor of an internal combustion engine is used. Summary

[0010] The present invention provides a method for detecting damage to a bearing of an internal combustion engine (hereinafter referred to as: engine), which performs processing by separating a vibration signal emanating from an engine and, while monitoring this, uses the vibration signal to confirm the damage to the bearing when the vibration exceeds a predetermined number of times it is input or occurs, even without adding separate hardware.

[0011] A method for detecting damage to an engine bearing using a vibration signal to solve the problem comprises: separating a signal, wherein a vibration signal of an engine, detected by a vibration detection device installed on one side of the engine or engine-side of the vehicle, into a vibration signal due to combustion knock and into a vibration signal of a bearing installed between a crankpin and a connecting rod (e.g., connecting rod); processing a signal, wherein a signal with a predetermined natural frequency band is processed by a signal processing filter.extracted and integrated from a vibration signal of the bearing, determining bearing damage by ascertaining whether, in a predetermined, specific engine operating condition (hereinafter also referred to as: engine operating condition), the bearing vibration signal is greater than a predetermined bearing failure threshold in order to detect damage (e.g., breakage or destruction) of the bearing during engine operation, and confirming bearing damage by confirming that the bearing is damaged, and the bearing vibration signal can be distinguished from the vibration signal by combustion knock according to the specific engine operating condition or a crankshaft rotation angle.

[0012] The specific engine state condition may, for example, be any state in which the engine is in an output deceleration condition or an initial deceleration condition (e.g., a condition in which the engine speed is reduced) in which deceleration begins, or in a state in which the engine enters an idle state during deceleration.

[0013] The state in which the engine enters an idle state during deceleration can, for example, include a state in which the engine enters an idle state with a fuel cut-off state during deceleration, and a state in which the engine enters an idle state without a fuel cut-off state during deceleration.

[0014] The method for detecting engine bearing damage using the vibration signal may, for example, include in the specific engine condition: increasing a respective monitoring counter for the specific engine condition, and may, for example, after detecting the bearing damage, further include increasing a damage counter or damaged bearing counter each time the bearing vibration signal is greater than a predetermined damaged bearing threshold.

[0015] Confirming the damage to the bearing can, for example, confirm the damage to the bearing under the condition in which the increased monitoring counter is less than or equal to a predetermined damage-detecting accumulation monitoring counter.

[0016] The vibration signal of the bearing can, for example, be captured as one that is generated in a predetermined detection section with respect to the rotation angle of the crankshaft.

[0017] The detection section is defined for each cylinder, for example, and is a specific angular range before and after top dead center (TDC).

[0018] The procedure for detecting engine bearing damage using the vibration signal may, after confirming bearing damage, include, for example: an emergency-home mode which limits the engine speed to a predetermined, safe maximum speed or less, or the operation of a warning device installed inside the vehicle to warn an occupant of bearing damage when the bearing is damaged.

[0019] A method for detecting damage to an engine bearing using a vibration signal may, for example, include: signal separation, wherein an engine vibration signal, detected by a vibration sensing device installed on one side of the engine or on the engine side of the vehicle, is separated into a vibration signal due to combustion knock and a vibration signal of a bearing installed between a crankpin and a connecting rod (e.g., connecting rod); signal processing, wherein a signal with a predetermined natural frequency band is extracted and integrated from the bearing vibration signal by a signal processing filter; and increasing a damage counter.The bearing damage counter is triggered each time the bearing vibration signal exceeds a predetermined bearing damage threshold for each specific engine operating condition in a predetermined specific engine operating condition to detect bearing damage during engine operation, and to confirm bearing damage, thereby confirming that the bearing is damaged, and the bearing damage confirmation can confirm the bearing damage under the condition in which the increased monitoring counter is less than or equal to a predetermined damage-detecting accumulation monitoring counter.

[0020] The specific engine condition condition may, for example, be any of the following: a state in which the engine is in an exit braking or at the beginning of braking, or a state in which the engine enters an idle state during braking, or a state in which the engine enters an idle state in a fuel cut-off state during braking.

[0021] The method for detecting damage to the motor bearing using the vibration signal may, for example, further include increasing a monitoring counter for each specific motor operating condition, and confirming the damage to the bearing confirms the damage to the bearing when the increased damage counter reaches the damage-confirming accumulation damage counter, provided that the increased monitoring counter is less than or equal to the predetermined damage-detecting accumulation monitoring counter.

[0022] Furthermore, a method for detecting damage to an engine bearing using a vibration signal may, for example, include: signal separation, wherein a vibration signal from an engine, detected by a vibration sensing device installed on one side of the engine or on the engine side of the vehicle, is separated into a vibration signal due to combustion knock and a vibration signal from a bearing installed between a crankpin and a connecting rod (e.g., connecting rod); signal processing, wherein a signal with a predetermined natural frequency band is processed by a signal processing filter from orthe vibration signal of the bearing is extracted and integrated, determining bearing damage by determining whether the bearing vibration signal is greater than a predetermined bearing damage threshold in a predetermined, specific engine operating condition to detect bearing damage during engine operation, and confirming bearing damage by confirming that the bearing is damaged, whereby the bearing vibration signal can also be detected in a predetermined detection section with reference to a crankshaft rotation angle.

[0023] The detection section can, for example, be defined separately for each cylinder according to the rotation angle of the crankshaft.

[0024] The detection section can, for example, be shaped within a predetermined angular range depending on the ignition timing of each cylinder.

[0025] The detection section can, for example, be a specific angular range before and after the top dead center (TDC) of each cylinder.

[0026] The method for detecting damage to the engine bearing using the vibration signal can further include, in the specific engine condition, an incrementing of a monitoring counter for each specific engine condition and an incrementing of a damage counter each time the vibration signal of the bearing is greater than the predetermined bearing damage threshold.

[0027] Confirming the damage to the bearing can, for example, confirm the damage to the bearing under the condition in which the increased monitoring counter is less than or equal to a predetermined damage-detecting accumulation monitoring counter.

[0028] The signal processing can, for example, define 1.5 kHz to 2.5 kHz in the vibration signal generated by the bearing as a central or mid-frequency, define a frequency band within a predetermined frequency band in or around the central or mid-frequency (e.g., with the central or mid-frequency in the middle of the frequency band) as a natural frequency band, and remove any signal other than the natural frequency band.

[0029] According to the method for detecting engine bearing damage using the vibration signal of the present invention, which has the configuration described above, it is possible to detect bearing damage by processing the vibration signal input from the knock sensor already mounted on the engine, without adding a separate hardware component. In particular, it is possible to accurately detect bearing damage by means of the distinguishable vibration caused by the bearing damage in a state where a load applied to the bearing changes suddenly while the vehicle is decelerating.

[0030] It is possible to detect bearing damage early on, thus preventing the engine from being damaged by driving the vehicle in a condition where the bearing is already damaged.

[0031] Furthermore, it is possible to enter an emergency return-to-home mode of the vehicle when bearing damage is detected, which will take the vehicle to a safe area or repair shop while preventing the bearing damage from progressing further.

[0032] Furthermore, it is possible to enable the driver to detect this, which can then trigger maintenance.

[0033] Then it is possible to identify which cylinder bearing is the defective one. Therefore, it is possible to replace the defective bearing directly without having to search for the cylinder bearing, which can reduce the time required for bearing replacement.

[0034] Further areas of application will become clear from the description given herein. It should be understood that the description and specific examples are intended solely for illustrative purposes and are not meant to limit the scope of the present invention. Brief description of the drawings

[0035] To better understand the invention, numerous embodiments are described below by means of examples, with reference to the accompanying drawings, which: Fig. 1 a perspective view or cross-sectional view which shows a process in which a bearing seizes on a section in which a connecting rod and a crank pin are connected in a motor, Fig. 2 is a cross-sectional view showing a process in which a bearing seizes on a section to which a connecting rod and a crankpin are connected in a motor, Fig. 3 is a cross-sectional view showing a process in which a bearing seizes on a section in which a connecting rod and a crankpin are connected in a motor, Fig. 4 is a block diagram showing a system for executing a method for detecting damage to the engine bearing using a vibration signal in an embodiment of the present invention, Fig. 5 is a flowchart showing the method for detecting damage to the engine bearing using the vibration signal in an embodiment of the present invention, Fig. 6 is a representation which shows an example in which a detection section that detects the vibration signal of the bearing is defined for each cylinder according to a rotation angle of a crankshaft, Fig. 7A is a graph showing a variation in the load on the connecting rod during an initial deceleration of the motor. Fig. 7B is a graph showing the state of the motor during output braking and the state of a knock sensor during normal motor operation. Fig. 7C is a graph which shows a state of the motor during output braking and a state of a knock sensor on the motor with the damaged bearing, Fig. 8A is a graph showing a variation in the load on the connecting rod when entering idle mode during engine deceleration. Fig. Figure 8B is a graph showing the state of the engine when entering idle during deceleration and the state of the knock sensor during normal engine operation. Fig. 8C is a graph which shows the state of the engine when entering idle during braking and the state of the knock sensor in the engine with the damaged bearing. Fig. 9A is a graph showing a variation in the load on the connecting rod when entering idle in a fuel shut-off state during engine deceleration, Fig. 9B is a graph showing the state of the engine when entering idle mode, the fuel cut-off state during deceleration, and the state of the knock sensor during normal engine operation. Fig. 9C is a graph which shows the state of the engine when entering idle in the fuel cut-off state during braking and the state of the knock sensor in the engine with the damaged bearing, Fig. 10A is a representation which shows a bearing damage threshold value according to each operating condition in the method for detecting bearing damage using the vibration signal in an embodiment of the present invention, Fig. Figure 10B is a representation showing a bearing damage threshold value according to each operating condition in the method for detecting bearing damage using the vibration signal in an embodiment of the present invention, Fig. Figure 10C is a representation showing a bearing damage threshold value according to each operating condition in the method for detecting bearing damage using the vibration signal in an embodiment of the present invention, and Fig. 11 is a graph which shows states of a vehicle speed, an accelerator pedal value, an engine speed and a sensor signal before and after confirmation of the damage in the method for detecting the damage of the engine bearing using the vibration signal in an embodiment of the present invention.

[0036] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present invention in any way. Detailed description of specific embodiments

[0037] The following description is merely exemplary and is not intended to limit the present disclosure, application, or uses thereof. It should be clear that reference numerals corresponding throughout the drawings denote identical or corresponding parts and features.

[0038] The following describes in detail a method for detecting damage to a bearing of an engine using a vibration signal according to the present invention with reference to the accompanying drawings.

[0039] First, a system for carrying out a method for detecting damage to a bearing of an engine using a vibration signal according to the present invention is described as follows.

[0040] As it is in the Fig. As shown in Figure 4, the system includes a knock sensor 15, which is an example of a vibration detection device, installed on one side of a motor 10, i.e., on the motor side, to detect knocking or combustion of the motor (hereinafter referred to as knocking) by measuring the vibration emanating from the motor 10, and a control unit 20 for controlling the operation of the motor 10, which determines that a bearing 13 of the motor 10 is damaged if the magnitude of a vibration signal caused by damage to the bearing is greater than a bearing failure threshold value.

[0041] The knock sensor 15, which is a means of detecting the vibration generated by the motor 10 during its operation, is installed on one side of the motor 10. The knock sensor 15 detects and generates the vibration signal produced by knocking when it occurs during combustion.

[0042] In the present disclosure, taking into account that the bearing 13 is installed on a section where the crankpin 12b of the crankshaft 12 and the connecting rod 11 (e.g. connecting rod) are connected to each other, and vibrations are generated even when it is damaged, the knock sensor 15 detects the vibration due to the damage to the bearing 13 as well as the vibration generated by the knocking.

[0043] The bearing 13 rotates around the crankpin 12b when the crankshaft 12 is rotated (the bearing rotates around the crankpin) and simultaneously rotates around the crankshaft 12 with a path formed by the crankpin 12b (the bearing runs around the crankshaft).

[0044] In general, the bearing supporting a rotating shaft (e.g., crankshaft) receives a constant force due to the rotation, regardless of the phase.

[0045] However, the combustion pressure generated in a combustion chamber and inertia from the operation of a piston 14 and the connecting rod 11 act on the bearing 13, while the bearing 13 (hereinafter referred to as a bearing installed on a crankpin of the crankshaft), which is installed on the crankpin 12b of the crankshaft 12, performs a movement (rotation and revolution) with respect to the pivot point of the crankshaft 12. Since this force (the force due to the combustion pressure and the force due to inertia) varies according to the phase of the crankshaft 12, there is a characteristic such that the force acting on the bearing 13 differs from the force acting on the bearing 13 according to the phase of the crankshaft 12. In the present invention, damage to the bearing 13, which is installed on the crankpin 12b, is detected using this characteristic.

[0046] However, in the detected vibration, which is detected by the knock sensor 15, the knocking and the damage to the bearing are detected by signal separation or signal processing.

[0047] The vibration signal detected by the knock sensor 15 can also confirm which cylinder bearing 13 is damaged by processing the window (detection section), which is a specific rotation angle range of the engine that is capable of generating a signal according to the rotation angle of the crankshaft (an X-axis in the Fig. 6: one cycle consists of two rotations or twice the rotation angle of the crankshaft).

[0048] As is particularly evident in the Fig. As shown in Figure 6, it is possible to detect the damage to bearing 13 by defining a detection section for each cylinder. The detection section can be defined for the crankshaft rotation angle. At this point, the detection section can also be defined for each cylinder. As shown in the Fig. As shown in Figure 6, it is possible to define the detection sections A1 to A4 for each cylinder in order to detect bearing vibration signals from the first to the fourth cylinder.

[0049] The detection section can be defined from immediately before top dead center (TDC) of each cylinder to a predetermined angle after TDC. In particular, the starting point of the detection section can be located between an ignition point and TDC. The load on the connecting rod 11 can increase rapidly from the ignition point in each cylinder, thereby capturing the vibration signal of the bearing 13 in a section where the load on the connecting rod 11 increases.

[0050] Therefore, it is possible to confirm which cylinder bearing is damaged in order to generate the bearing failure signal.

[0051] The reason why the piston detects or experiences damage to bearing 13 around the TDC (Torque Discharge Center) is as follows. If the engine bearing is damaged, noises occur around the piston's TDC. A knocking noise occurs in bearing 13, whose clearance is enlarged, while the combustion pressure in the combustion chamber is at its maximum around the piston's TDC. Furthermore, the gap between bearing 13 and the crankpin 12b of the crankshaft 12 is increased, causing noises as the top surface of the piston 14 collides with the cylinder head. For this reason, the vibration characteristics around the piston's TDC are monitored.

[0052] In addition to the knock sensor 15, numerous sensors for measuring or recording the condition of the engine 10 are installed on one side of the engine 10 or on the engine side. For example, a temperature sensor 16 can be installed to measure the temperature of the engine oil in order to confirm the engine temperature.

[0053] The control unit 20 processes the input signal from the knock sensor 15 to determine whether the connecting rod bearing 13 is damaged, while the combustion of the engine 10 is controlled according to the driver's input. For example, the control unit 20 can include an engine control unit 21 for controlling the combustion of the engine 10 according to the driver's input, a signal processing unit 22 for separating the signal from the knock sensor 15 into the vibration signal caused by the knocking and the vibration signal caused by the bearing damage, which quantifies the bearing signal, and a bearing failure detection unit 23 for determining the damage to the bearing 13 from the bearing failure signal processed by the signal processing unit 22.Since the control unit 20 stores a method for detecting damage to the motor bearing using the vibration signal as logic as described later, the method for detecting damage to the motor bearing using the vibration signal is executed by the control unit 20.

[0054] The engine control unit 21 controls the combustion of the engine 10, enabling the engine 10 to generate the required torque according to driver input, vehicle driving conditions, etc. Since the control of the engine 10 by the engine control unit 21 corresponds to the control of a typical engine 10, a detailed description of this is omitted.

[0055] The signal processing unit 22 separates the vibration signal caused by the damage to the bearing 13 from the vibration signal caused by combustion knocking among the signals output by the knock sensor 15. The knock signal separated by the signal processing unit 22 is used to control the knocking via a separate knock control logic. Specifically, it is processed as a quantized bearing signal by extracting, amplifying, and integrating a signal from a predetermined natural frequency band from the bearing signal separated by the signal processing unit 22.

[0056] The bearing failure detection unit 23 determines whether bearing 13 is damaged by comparing the bearing signal with a predetermined bearing failure threshold. The bearing failure detection unit 23 determines the damage to bearing 13 using the motor bearing failure detection method based on the vibration signal, as described later. If the bearing failure detection unit 23 determines that bearing 13 is damaged, the motor control unit 21 is activated so that the motor operates in an emergency limp-home mode.

[0057] A warning device alerts an occupant to detect damage to bearing 13 when the control unit 20 determines that bearing 13 is damaged.

[0058] For example, the warning device can be a warning lamp 31, which is installed inside the vehicle or on its dashboard. When damage to bearing 13 is detected, the control unit 20 illuminates the warning lamp 31 so that the occupant can recognize the damage to bearing 13.

[0059] Another example of a warning device could be a loudspeaker installed on the inside of the vehicle.

[0060] A method for detecting engine bearing damage using the vibration signal according to the present invention comprises separating S120 a signal in which the vibration signal of the engine 10, which is detected by the vibration detection means installed on the engine side of the vehicle, is separated into the vibration signal due to combustion knocking and the vibration signal generated by the bearing 13, processing S130 a signal in which the vibration signal generated by the bearing 13 is processed as a quantified bearing signal by extracting, amplifying and integrating a signal of a predetermined natural frequency band by a signal processing filter, and determining S160 the bearing damage by comparing whether the bearing signal is greater than a predetermined bearing damage threshold.

[0061] By performing a fast Fourier transform (FFT) on the signal measured by the knock sensor 15, it can be observed during braking that the engine with the damaged bearing 13 has a natural frequency of approximately 2 kHz compared to the normal engine. The frequency of combustion knock, as measured by the knock sensor 15, has inherent frequencies of, firstly, 5 to 6 kHz, secondly, 11 to 12 kHz, and thirdly, 15 to 16 kHz. When the bearing 13 is damaged, it has a natural frequency of around 2 kHz, thus detecting the damage to the bearing 13.

[0062] Furthermore, in a normal motor, when braking is performed during operation, the load acting on bearing 13 is reduced when the motor speed is reduced. However, in a motor with a damaged bearing, the clearance or play is increased due to the bearing damage, thus increasing the vibrations detected from motor 10. This has a different characteristic than the vibration caused by knocking, and the bearing damage is detected using this principle.

[0063] Fulfilling the diagnostic start condition S110 determines whether the vehicle's engine 10 is in a state suitable for detecting bearing 13 damage. Since the present invention detects bearing 13 damage using the vibration generated by the engine 10 during its operation, the engine 10 must be sufficiently warmed up to determine if its vibration signal is stable before the bearing 13 diagnosis is initiated. Before the engine 10 is warmed up, noise from friction between various components occurs, and the bearing 13 damage cannot be accurately diagnosed. Therefore, the system determines whether the engine 10 is warmed up, and the bearing 13 damage is diagnosed only when the engine is warmed up.Since the condition of the engine 10 is diagnosed using the vibration of the engine 10, the present invention determines whether it is warmed up based on the temperature of the engine oil instead of the temperature of the coolant. If the temperature T_oil of the engine oil is higher than a predetermined diagnostic output temperature T_THD (T_oil > T_THD), the diagnosis of damage to the bearing 13 can be initiated. Here, the diagnostic output temperature T_THD can be set to 80°C.

[0064] Separating signal S120 separates the signal measured by the vibration sensor installed on motor 10. Since the signal measured by the vibration sensor is a superimposed state of vibrations caused by motor 10 knocking and vibrations caused by damage to bearing 13, etc., the bearing vibration signal is separated from the vibration signals detected by the vibration sensor. The knock sensor can be used as the vibration sensor, and the knock sensor is described below as an example of such a device.

[0065] The process of separating the vibration signal from the bearing 13 among the vibration signals measured by the knock sensor 15 involves performing a fast Fourier transform on the vibration signal measured by the knock sensor 15 to isolate the frequency band (around 2 kHz) from the vibration signal of the bearing 13. The remaining frequency bands, i.e., 5 to 6 kHz in the first band, 11 to 12 kHz in the second band, and 15 to 16 kHz in the third band, are used to detect knocking. The frequency band (around 2 kHz) where the signal differs from that of the normal motor 10 is output when the bearing is damaged and is isolated and used to detect the damage to the bearing 13.

[0066] Processing signal S130 removes and quantifies noise or interference from the storage signal, which was separated when separating signal S120.

[0067] The S130 signal processing process treats the separated vibration signal of the bearing as a quantified bearing signal by extracting, amplifying and integrating a signal of a predetermined natural frequency through the signal processing filter.

[0068] The vibration signal from bearing 13 is passed through the signal processing filter to retain only the signal from the band adjacent to the natural frequency, thereby removing the signal from the remaining band. If vibration occurs in motor 10 due to damage to bearing 13, an abnormal signal is generated at approximately 2 kHz, which is different from knocking. Therefore, the signal processing S130 sets a center frequency, selected from a range of 1.5 to 2.5 kHz, and retains only the signals from adjacent bands within the predetermined range of this center frequency. For example, if the center frequency is set to 2 kHz (based on 2 kHz ± 0.435 kHz), only the signal from 1.565 kHz to 2.435 kHz remains, and other signals (lower than 1.565 kHz and higher than 2.435 kHz) are removed.The center frequency and the size of the adjacent band relative to the center frequency can be selected according to the situation.

[0069] The signals are then quantified by amplification, integration, etc., which allows them to be processed as the bearing signal for detecting the damage to bearing 13.

[0070] As described above, the bearing signal is processed into a noise suppression and quantification state and then compared with the bearing failure threshold.

[0071] Naturally, the process of detecting the knocking using the frequency bands of firstly 5 to 6 kHz, secondly 11 to 12 kHz and thirdly 15 to 16 kHz, which are not used when separating the signal S120, is processed or used separately independent of the present invention.

[0072] Separating signal S120 and processing signal S130 are performed continuously when motor 10 is operated after determining that the diagnostic start condition S110 has been met.

[0073] The engine condition determination S140 determines whether the engine condition is suitable for detecting damage to bearing 13. That is, it determines whether the engine condition 13 constitutes a specific engine condition that is an operating condition suitable for detecting damage to bearing 13 while the engine 10's operating condition is being recorded. In other words, the specific engine condition is a specific operating condition of the engine suitable for detecting damage to bearing 13 under numerous operating conditions of the engine 10.

[0074] Since whether the bearing 13 is damaged can mainly be monitored when the motor 10 is braking, it is recorded whether the motor 10 is in a braking state.

[0075] When the motor 10 is braked, the load applied to the bearing 13 is rapidly changed by the connecting rod 11, and, if the bearing 13 is in a damaged state, a distinguishable vibration signal is generated from the bearing 13, making it possible to detect the damage to the bearing 13 using this signal.

[0076] In particular, it is preferred that the engine state determination S140 determines whether the engine 10 is in a predetermined condition during deceleration. Therefore, the specific engine state condition detects whether the state of the engine 10 is any of the following: a deceleration output state, in which the engine speed begins to decrease; an idle entry state, which changes to idle speed during deceleration as the engine speed decreases; or an idle entry state in a fuel cut-off state during deceleration. Even if the engine 10 is in the output deceleration state, the idle entry state during deceleration, or the fuel cut-off state during deceleration, if the bearing 13 is not damaged, the force acting on the bearing 13 is small, so the signal generated by the bearing 13 is not large.However, if the bearing 13 is damaged, the vibration signal generated by the bearing 13 has a discriminatory power that exceeds a predetermined value, so that the present invention determines the damage to the bearing 13 using this.

[0077] That is, since the vibration signal due to the damage to the bearing 13, where the bearing 13 is installed between the crankpin 12b and the connecting rod 13, and the vibration signal due to the rotation of the crankshaft are distinguishable from each other according to the detected operating conditions of the engine, the damage to the bearing 13, which is installed between the crankpin 12b and the connecting rod 11, is detected using this.

[0078] The reason for recording the damage to bearing 13 in the vehicle braking condition is as follows.

[0079] When the vehicle decelerates due to a change in speed, the engine speed progressively decreases during medium and high-speed conditions. At this point, since the engine's output power is not required, the work required for combustion is rapidly reduced, and the amount of intake air is also reduced. As the intake air volume decreases, the amount of air to be compressed by piston 14 is also reduced, resulting in a small increase in pressure within the combustion chamber. While the pressure in the combustion chamber is low, the engine is operating at high speed, so there is a high probability that the piston will collide with the cylinder head due to its inertia as it rises to the TDC (Total Displacement Control).For this reason, as described above, since the noises occur due to bearing damage, the bearing damage is detected using the braking conditions.

[0080] Furthermore, determining the engine condition S140 can also detect whether the condition of the engine 10 is any of an idle operating condition or a part load operating condition.

[0081] The engine status determination S140 can determine the status of engine 10 by means of a speed signal which is input from engine 10 to control unit 20.

[0082] When separating signal S120, processing signal S130 and determining the motor state S140, the determination of the motor state S140 is carried out first, and afterwards the separation of signal S120 and the processing of signal S130 can also be carried out.

[0083] If the state of engine 10 is any of the braking output state, the idle entry state during braking, and the idle entry state in the fuel shut-off state during braking, an increase of a monitoring counter S150 is performed.

[0084] If the engine 10 is in the braking exit state, in the idle entry state during braking, or in the idle entry state in the fuel cut-off state during braking, the monitoring counter is incremented from a current monitoring counter (current monitoring counter → current monitoring counter + 1).

[0085] The counters used in the present invention are defined as follows.

[0086] The monitoring counter is a counter that increments each time the motor enters any of the specific motor operating conditions as described above.

[0087] A damage-detecting or damage-detecting accumulation monitoring counter (hereinafter referred to as: damage-detecting accumulation monitoring counter) is a reference for confirming the damage of bearing 13 by accumulating the monitoring counter by 1 for each specific motor condition and denotes a maximum value among the values ​​which are obtained by accumulating the monitoring counter.

[0088] The damage counter or damaged bearing counter is a counter that increases each time the bearing signal is equal to or greater than the damaged bearing threshold.

[0089] The damage-confirming, accumulative damage counter or damage bearing counter (hereinafter referred to as: damage-confirming accumulation damage counter) is a reference for confirming the damage of the bearing by accumulating the damage counter by 1 for each specific engine condition condition and denotes a maximum value among the values ​​obtained by accumulating the damage counter by 1.

[0090] Increasing the monitoring counter S150 only increments the counter while the engine is in the same state. For example, if the current engine state is again recorded as the idle entry state during deceleration, in a state where the current monitoring counter for the idle entry state during deceleration is "1", the monitoring counter for the idle entry state during deceleration will be incremented to "2". If the idle entry state is newly recorded in the fuel cut-off state during deceleration, the monitoring counter for the idle entry state during deceleration will remain unchanged and will be incremented (+1).

[0091] This is also the case in the remaining states, that is, the braking initial state or the idling entry state during braking or the idling entry state in the fuel shut-off state during braking, and the monitoring counter is incremented for the case in which the state of engine 10 is the same state, and the monitoring counter is handled independently of the states of the engine of different states.

[0092] As described above, for each specific engine condition, a comparison is made to see if the bearing vibration signal is greater than the predetermined bearing failure threshold, while the monitoring counter for the specific engine condition is incremented.

[0093] The S160 bearing failure detection system compares the bearing signal with the predetermined bearing failure threshold.

[0094] Determining the damaged bearing S160 determines whether the bearing signal is equal to or greater than the predetermined damaged bearing threshold by comparing the signal of bearing 13, which has been transformed during the processing of signal S130, with the damaged bearing threshold, thus determining that bearing 13 is damaged.

[0095] It is preferred that the bearing failure threshold is set differently according to the operating conditions of the engine 10. Furthermore, the bearing failure threshold can be set lower than the bearing failure threshold during initial deceleration if the idle entry condition is present during deceleration.

[0096] When determining the damaged bearing S160, increasing the damaged bearing counter S170 increases the damage counter for a current damage counter if the bearing signal is equal to or greater than the damaged bearing threshold (current damage counter → current damage counter +1).

[0097] If the bearing signal is equal to or greater than the defective bearing threshold, in a state where the current defective counter is "0", the defective counter is incremented to "1".

[0098] When increasing the damage counter S170, the reference for increasing the damage counter can be set differently depending on the detected engine operating state, that is, for each specific engine operating state. A reference for increasing the damage counter can be set differently when the engine operating state is the exit braking state, a reference for increasing the damage counter when the engine operating state is the idle entry state during braking, and a reference for increasing the damage counter when the engine operating state is the idle entry state in the fuel cut-off state during braking.

[0099] Confirming the damaged bearing S180 confirms the damage to bearing 13 using the damage counter.

[0100] Confirming the damage bearing S180 can confirm the damage of bearing 13 if the value obtained by accumulating the damage counter (accumulated damage counter) is equal to or greater than the predetermined, damage-confirming accumulation damage counter to confirm the damage of the bearing, provided that the value obtained by accumulating by increasing the monitoring counter (accumulated monitoring counter) is less than or equal to the predetermined, damage-detecting accumulation monitoring counter to confirm the damage of the bearing.The damage-confirming accumulation damage counter is a maximum value among the damage counters that have been accumulated to determine the damage to bearing 13, and the damage to bearing 13 is confirmed if the increased damage counter is equal to or greater than the damage-confirming accumulation damage counter, provided that the increased monitoring counter is less than or equal to the damage-determining accumulation monitoring counter.

[0101] Here, the condition in which the increased monitoring counter is less than or equal to the damage-determining accumulation monitoring counter can be the case in which the increased monitoring counter is incremented to reach the damage-determining accumulation monitoring counter, and can be the case in which the increased monitoring counter has already reached the damage-determining accumulation monitoring counter. This can also include the case in which the increased monitoring counter has reached the damage-determining accumulation monitoring counter, and then a new monitoring counter is added at the same time as the oldest monitoring counter is deleted.

[0102] Therefore, if the accumulated value of the damage counter reaches the damage-confirming accumulation damage counter even before the value obtained by accumulating the monitoring counter, which reaches the damage-detecting accumulation monitoring counter, the damage is confirmed. Furthermore, the same applies if the accumulated value of the monitoring counter has already reached the damage-detecting accumulation monitoring counter. Additionally, after the accumulated value of the monitoring counter reaches the damage-detecting accumulation monitoring counter, the oldest monitoring counter is cleared, and a new monitoring cycle is performed to confirm the damage by comparing the accumulated value of the damage counter with the damage-confirming accumulation damage counter while the damage-detecting accumulation monitoring counter remains active.

[0103] The fact that it is recorded that the bearing is damaged at the (reaching) damage-confirming accumulation damage counter or more, under the condition that the increased monitoring counter reaches or maintains the damage-detecting accumulation monitoring counter, means that bearing 13 is damaged and that the signal relating to the damaged bearing is frequently or repeatedly output.

[0104] As an example of confirming damage to bearing S180, if the damage-detecting accumulation monitoring counter is set to "5" and the damage-confirming accumulation damage counter is set to "2", it can be confirmed that bearing 13 is damaged if the damage-confirming accumulation damage counter is 2 or higher in a state where the damage-detecting accumulation monitoring counter is within 5.

[0105] Here, the damage-detecting accumulation monitoring counter and the damage-confirming accumulation damage counter, which are each set to confirm the damage to the bearing, can be set differently if necessary.

[0106] In particular, the damage-detecting accumulation monitoring counter and the damage-confirming accumulation damage counter can be set differently according to the specific engine operating conditions. For example, if the engine operating condition is detected as the initial deceleration, the damage-detecting accumulation monitoring counter and the damage-confirming accumulation damage counter can be set to "5" and "2," respectively, to confirm the damage to bearing 13. If the specific engine operating condition is idling during deceleration, or idling in the fuel cut-off state during deceleration, then, instead of the above, the damage-detecting accumulation monitoring counter and the damage-confirming accumulation damage counter can be set to values ​​other than "5" and "2," respectively.

[0107] Furthermore, when the damage-detecting accumulation monitoring counter is reached, a new monitoring counter is added simultaneously with the deletion of the oldest monitoring counter, and the accumulation monitoring counter is constantly maintained as the damage-detecting accumulation monitoring counter, which is the maximum value, thus recording the damage to warehouse 13. That is, when the accumulation monitoring counter reaches "5", which is set as the damage-detecting accumulation monitoring counter, the damage to the warehouse can be determined by counting the damage-confirming accumulation damage counter, provided that it is less than or equal to the damage-detecting accumulation monitoring counter while the damage-detecting accumulation monitoring counter is maintained (e.g., 5).

[0108] If the monitoring counter, which is incremented by 1 for each specific motor condition condition, is equal to the damage-detecting accumulation monitoring counter as the condition for determining whether the damage to bearing S180 is confirmed (first condition), i.e., if the maximum value among the accumulation monitoring counters is equal to the damage-detecting accumulation monitoring counter, the confirmation of the damage to bearing S180 is performed.

[0109] Furthermore, confirming the damage to bearing S180 determines whether the value achieved by accumulating the damage counter reaches the damage-confirming accumulation damage counter (second condition).

[0110] This means that confirming the damage of the bearing S180 confirms that the bearing is damaged when the value obtained by accumulating the damage counter reaches the damage-confirmed accumulation damage counter, while the value obtained by accumulating the monitoring counter is equal to the damage-detecting accumulation monitoring counter.

[0111] If either of these two conditions is not met (if the value obtained by accumulating the monitoring counter is less than the damage-detecting accumulation monitoring counter, or if the value obtained by accumulating the damage counter is less than the damage-confirming accumulation damage counter), the procedure reverts to the state prior to determining the engine condition S140, to determine whether the specific engine condition condition has occurred.

[0112] Therefore, it is preferable that the determination of the damage to bearing S180 be carried out preferentially if the first condition and the second condition are met.

[0113] When confirming the damage to bearing S180, since the damage to the bearing is certain if the value obtained by accumulating the damage counter has already reached the damage-confirming accumulation damage counter, the damage to the bearing can be confirmed even if the accumulation monitoring counter is smaller than the damage-detecting accumulation monitoring counter.

[0114] This means that when confirming damage to bearing S180, even if the accumulation monitoring counter is smaller than the damage-detecting accumulation monitoring counter, the damage to the bearing can be confirmed if the value reached by accumulating the damage counter reaches the damage-confirming accumulation damage counter.

[0115] This is because, when the monitoring counter accumulates and later becomes equal to the damage-detecting accumulation monitoring counter, the second condition is already met, so that confirmation of the damage to the bearing is certain.

[0116] For example, the damage counter can be accumulated for the same engine condition to confirm bearing damage. If the engine is running at idle, bearing damage can be confirmed when the damage-confirming accumulation damage counter reaches 3 or more, regardless of the damage-detecting accumulation monitoring counter.

[0117] If, during the confirmation of damage to bearing S180, it is determined that bearing 13 is not damaged, the system reverts to the time before the monitoring counter S150 incremented in order to continuously monitor the damage to bearing 13. This can correspond to the case where the accumulation monitoring counter is lower than the damage-detecting accumulation monitoring counter, or to the case where the accumulation damage counter is lower than the damage-confirming accumulation damage counter.

[0118] An emergency return-to-home mode S191 is executed when it is confirmed that bearing 13 is damaged.

[0119] The emergency return-to-home mode S191 limits the speed of motor 10 to a predetermined, safe maximum speed or less, thus preventing further damage to bearing 13. Because the maximum speed of motor 10 is limited, the damage to bearing 13 can be prevented from progressing.

[0120] The emergency home mode S191 also limits the value of an accelerator pedal to a predetermined value, so that appropriate shifting can be performed in a state where the engine speed is limited.

[0121] Furthermore, the motor 10 is operated at a predetermined minimum motor operating speed, so that the operation of the motor can be maintained.

[0122] As described above, if the bearing is damaged, the vehicle will be permitted to operate in a condition where the output power has been limited, provided that the operation of the engine is maintained by the Emergency Home Mode S191, so that the vehicle can be moved to a location where repairs can be carried out.

[0123] The operation of a warning device S192 is also carried out so that the driver can detect the bearing damage. If, upon confirmation of bearing damage S180, it is confirmed that bearing 13 is damaged, the warning device installed in the vehicle is activated so that the occupant can detect this. For example, a warning lamp is installed on one side of the vehicle interior or on an instrument panel, and warning lamp 31 is illuminated so that the occupant detects the damage to bearing 13. The operation of the warning device S192 can not only illuminate warning lamp 31, but also alert the occupant to the bearing damage by means of a warning sound or vibration, thus preventing the progression of the seizure.

[0124] The Fig. Figure 11 shows a vehicle speed, accelerator pedal position, engine speed, and the state of a sensor signal before and after the bearing damage is confirmed. The engine with the damaged bearing has a large, measured, and processed bearing signal from the knock sensor 15 due to the damage to bearing 13 before the damage to bearing 13 is detected (see section A in Fig. 11) However, after the damage to bearing 13 has been detected and bearing 13 is damaged during the execution of the emergency return-to-home mode S191 and the operation of the warning device S192, but in a condition in which the engine speed 10 and the accelerator pedal value are limited, the bearing signal measured by the knock sensor 15 may be reduced to a level at which normal bearing behavior is present (see section B in the Fig. 11), thereby preventing the damage to bearing 13 from progressing. At this point, the driver can detect the damage to the bearing by activating the warning device, such as warning lamp 31, which allows the vehicle to be driven to a workshop for repairs to be carried out on the damaged bearing 13.

[0125] The Fig. Figures 7A to 10C show graphs of a load acting on the connecting rod 11 and the condition of the bearing 13 under normal circumstances and at the time of damage for each condition of the motor 10. Embodiments of determining the motor condition S140 to confirm the damage of the bearing S180 according to the condition of the motor 10 are described below.

[0126] First, they show Fig. 7A, Fig. 7B and Fig. 7C a process in which the motor 10, during an initial deceleration, determines a variation in the load acting on the bearing 13, and the damage for the cases in which the bearing 13 is normal and damaged.

[0127] If bearing 13 is normal, the engine 10 is operated by performing a deceleration accompanied by a fuel cut-off (PUC), a deceleration not accompanied by a fuel cut-off (PU), a part-load condition (PL), and an idle condition (IS), etc., as the vehicle moves. If a condition exists in which bearing 13 is not damaged (see Fig. 7B), the monitoring counter is also incremented by 1 each time the condition PU is detected for motor 10, which is initiating braking, when determining the motor condition S140. Simultaneously, the bearing signal also increases due to a change in the bearing load at the start of braking, but the damage counter is not incremented because the magnitude of the position signal is below a bearing damage threshold.

[0128] In the state in which the bearing is damaged (see Fig. 7C), the monitoring counter is incremented by 1 each time motor 10 enters braking state PU S140. Simultaneously, when the magnitude of the bearing signal, which is in a state where it has increased due to a change in bearing load, is compared to the bearing failure threshold S160, the bearing signal exceeds the threshold. Each time the bearing signal exceeds the threshold, the failure counter is incremented S170 and accumulated. In the state where the bearing is damaged, as opposed to the state where the bearing is normal, distinguishable noises and vibrations occur when the bearing load is rapidly reduced at the point when the vehicle begins to brake. These are detected and accumulated.

[0129] In the Fig. 7C the monitoring counter and the damage counter are accumulated, so that the damage counter accumulates to 3 (accumulation damage counter = 3) while the monitoring counter accumulates to 5 (damage-detecting accumulation monitoring counter = 5) to become a predetermined threshold (damage-confirming accumulation damage counter) or more, so that it is confirmed that bearing 13 is damaged S180.

[0130] As described above, if the bearing damage is confirmed during an initial braking maneuver S180, either the Emergency Home Mode S191 and the Operation of the Warning Device S192, or both the Emergency Home Mode S191 and the Operation of the Warning Device S192, will be executed.

[0131] Furthermore, the process described above can be confirmed in the same way as during initial braking in a fuel shut-off state.

[0132] The Fig. 8A, Fig. 8B and Fig. Figure 8C shows a process for determining a variation in the load acting on the connecting rod 11 and the resulting damage in cases where the bearing 13 is normal or damaged. The load variation occurs to change the speed of the motor 10 to idle speed as the motor 10 enters idle during deceleration. In the condition where the bearing is damaged, compared to the condition where the bearing is normal, a relatively strong vibration occurs at the time of the load variation, which is then detected to determine the bearing damage.

[0133] If bearing 13 is normal, the engine 10 is operated by deceleration accompanied by fuel cut-off PUC, deceleration not accompanied by fuel cut-off PU, the part-load condition PL, the idle condition IS, etc., when the vehicle is moving. If bearing 13 is not damaged (see Fig. 8B), the monitoring counter is also incremented by 1 each time the state in which idling occurs during deceleration (PU → IS) is detected for motor 10 when determining motor state S140. At this point, when idling occurs during deceleration (PU → IS), the bearing signal is also incremented due to the change in bearing load, but the damage counter is not incremented because the bearing magnitude is below the damage bearing threshold.

[0134] However, if the condition is detected for motor 10 in which idling during deceleration (PU → IS) occurs during operation in the state where bearing 13 is damaged (S140), the monitoring counter is also incremented by 1 (S150). If the motor idles during deceleration (PU → IS) in the state where bearing 13 is not damaged, the vibration originating from a section where bearing 13 is installed is greater than normal because the gap is increased due to the damage to bearing 13, thus incrementing the damage counter (S170) and accumulating the signal each time the bearing exceeds the damage threshold.

[0135] If the accumulation damage counter exceeds "2", which is the preset damage-confirming accumulation damage counter, while the damage-determining accumulation monitoring counter for the accumulation monitoring counter, which confirms the bearing damage, accumulates to "5", it is confirmed that bearing 13 is damaged S180. In the Fig. 8C is the reason for confirming the damage to the bearing when the accumulation measure of the damage counter (accumulation damage counter) becomes “4” instead of “3”, because the accumulation monitoring counter becomes 5, which is set as the damage-detecting accumulation monitoring counter.

[0136] As described above, if the damage to bearing 13 is confirmed by detecting the damage to the bearing while entering idle during deceleration (PU → IS) S180, either the Emergency Home Mode S191 and the Warning Device Operation S192, or both the Emergency Home Mode S191 and the Warning Device Operation S192, will be executed.

[0137] Furthermore, the process described above can be carried out in the same way during initial braking in a fuel shut-off state.

[0138] The Fig. 9A, Fig. 9B and Fig. Figure 9C shows a process for determining a variation in the load acting on the connecting rod 11 and the resulting damage in cases where the bearing 13 is normal or damaged, while the engine enters idle in the fuel cut-off state during deceleration. When the engine 10 enters idle in the fuel cut-off state during deceleration, it restarts combustion to change the speed from the fuel cut-off state during deceleration to idle, causing a variation in the load. At this point, if the bearing is damaged, distinguishable vibrations occur compared to the normal state, thus detecting the damage to the bearing 13.

[0139] If bearing 13 is normal, the engine 10 is operated by performing braking accompanied by fuel cut-off PUC, braking not accompanied by fuel cut-off PU, the part-load condition PL, the idle condition IS, etc., as the vehicle moves. If bearing 13 is not damaged (see Fig. 9B), the monitoring counter is also incremented by 1 each time, for engine 10, when determining engine state S140, the state of entering idle in the fuel cut-off state during deceleration (PUC → IS) is determined. At the same time, when entering idle in the fuel cut-off state during deceleration (PUC → IS), the bearing signal changes due to the change in bearing load. Although the magnitude of the position signal is greater than that in the embodiments described above, which are in the Fig. 7B and Fig. 8B shown, is even in the Fig. 9B the magnitude of the position signal below the damage threshold, thereby continuously monitoring the condition of the bearing without increasing the damage counter.

[0140] However, if, during operation of engine 10 in the condition where bearing 13 is damaged (S140), the condition in which the engine enters idle in the fuel cut-off state during deceleration (PUC → IS) is detected, the monitoring counter is also incremented by 1 (S150). In the condition where bearing 13 is damaged, when engine 10 enters idle in the fuel cut-off state during deceleration (PUC → IS), the vibration originating from the section where bearing 13 is installed is detected as larger than normal because the gap is increased due to the damage to bearing 13. At this point, part of the position signal exceeds the bearing failure threshold, while the remainder does not.Each time the engine 10 enters idle in the fuel cut-off state during deceleration (PUC → IS) S140, the monitoring counter is incremented S150 and the damage counter is incremented each time the bearing signal exceeds the damage bearing threshold S160.

[0141] If the accumulation damage counter is the predetermined threshold (damage-confirming accumulation damage counter = "2") or higher, while the accumulation monitoring counter is the damage-detecting accumulation monitoring counter ("5"), it is confirmed that bearing 13 is damaged S180.

[0142] As described above, if the damage to bearing 13 is confirmed by detecting the damage to the bearing each time the engine enters idle in the fuel cut-off state during deceleration (PUC → IS), either the Emergency Home Mode S191 and the Operation of Warning Device S192 will be executed, or both will be executed.

[0143] The Fig. Figures 10A to 10C show an example of a bearing failure threshold for detecting bearing damage according to the operating state of motor 10 from the signal generated by the bearing. Fig. 10A is an example of setting the bearing failure threshold in the state in which motor 10 is in the initial braking state (PU), which Fig. 10B is an example of setting the bearing failure threshold in the state in which the engine enters idle during deceleration (PU → IS), and the Fig. 10C is an example of setting the bearing failure threshold in the state in which the engine enters idle in the fuel cut-off state during deceleration (PUC→IS).

[0144] When each of the drawings is considered, the distribution of the vibration signal is relatively concentrated at the bearing failure threshold, or more so under normal circumstances, while there are many cases which exceed the bearing failure threshold, and the distribution of these is also distributed in the state in which the bearing is damaged.

[0145] Furthermore, the bearing failure threshold is set differently depending on the engine's operating condition. This is because the levels of the bearing signals measured by the knock sensor 15 differ according to the respective engine operating conditions, meaning that an appropriate bearing failure threshold will vary depending on the operating conditions. Fig. Figures 10A to 10C show an example of the bearing failure threshold in each operating condition of the engine, and the bearing failure threshold can be appropriately changed according to a different value.

Claims

[1] A method for detecting damage to a bearing of an engine using a vibration signal, comprising: Separating (S120) a vibration signal from the engine, which is detected by a vibration sensor installed on the engine side of a vehicle, into a vibration signal due to combustion knock and into a vibration signal from a bearing installed between a crankpin and a connecting rod, Extracting (S130), through a signal processing filter, a signal in a predetermined natural frequency band from the vibration signal of the bearing, Determine (S140), in a predetermined engine operating condition, whether the bearing vibration signal is greater than a predetermined bearing failure threshold in order to detect bearing damage during engine operation, and Confirm (S160) that the bearing is damaged, where the vibration signal of the bearing is distinguishable from the vibration signal caused by combustion knocking based on the predetermined engine operating condition or a rotation angle of a crankshaft. [2] The method according to claim 1, wherein the method comprises: Receiving the vibration signal of the bearing from a predetermined detection section of the crankshaft's rotation angle. [3] The method according to claim 1 or 2, wherein the engine condition condition comprises: at least one of a state in which the engine enters an initial braking state that begins braking, or of a state in which the engine enters an idle state during braking. [4] The method according to claim 3, wherein the state in which the engine enters the idle state during braking comprises: a state in which the engine enters an idle state in a fuel cut-off state during deceleration, and a state in which the engine enters the idle state without the fuel cut-off state during braking. [5] The method according to claim 3 or 4, wherein the method comprises: Increasing (S150) a monitoring counter for each engine condition, Increasing a damage counter when the bearing's vibration signal is greater than the predetermined damage bearing threshold, and Confirm (S180) the damage to the bearing when the increased monitoring counter is less than or equal to a predetermined damage-detecting accumulation monitoring counter. [6] The method according to any of the preceding claims, wherein the method further comprises: Reduce, by the motor, the motor speed to a predetermined, maximum motor safety speed or less, and If the bearing is damaged, notify (S192) an occupant of the damage to the bearing by operating an alarm installed in the vehicle. [7] The method according to any one of the preceding claims, wherein the method comprises: Setting a center frequency of 1.5 kHz to 2.5 kHz from the bearing's vibration signal, Defining a frequency band within a predetermined frequency band as a natural frequency band and Removing a signal that is not within the natural frequency band. [8] A method for detecting damage to a motor bearing using a vibration signal, comprising: Separating (S120) a vibration signal from the engine, which is detected by a vibration sensor installed on the engine side of a vehicle, into a vibration signal due to combustion knock and into a vibration signal from a bearing installed between a crankpin and a connecting rod, Extracting (S130), through a signal processing filter, a signal in a predetermined natural frequency band from the vibration signal of the bearing, Increase (S170), in a predetermined engine operating condition, a damage counter, if the bearing vibration signal is greater than a predetermined bearing damage threshold for each engine operating condition, in order to detect bearing damage during engine operation, and Confirm (S160) the damage to the bearing when the increased damage counter is less than or equal to a predetermined damage-detecting accumulation monitoring counter. [9] The method according to claim 8, wherein the engine condition condition comprises: at least one of a state in which the engine enters an initial braking state which begins braking, a state in which the engine enters an idle state during braking, or a state in which the engine enters the idle state in a fuel shut-off state during braking. [10] The method according to claim 8 or 9, wherein the method further comprises: Increasing (S150) a monitoring counter for each engine condition and Confirm (S180) the damage to the bearing when the increased monitoring counter is less than or equal to a predetermined damage-detecting accumulation monitoring counter. [11] A method for detecting damage to a bearing of an engine using a vibration signal, comprising: Separating (S120) a vibration signal from the engine, which is detected by a vibration sensor installed on the engine side of a vehicle, into a vibration signal due to combustion knock and into a vibration signal from a bearing, which is installed between a crank pin and a connecting rod Extracting (S130), through a signal processing filter, a signal in a predetermined natural frequency band from the vibration signal of the bearing, Determine (S160), in a predetermined engine operating condition, whether the bearing vibration signal is greater than a predetermined bearing failure threshold, in order to detect bearing damage during engine operation and Confirm (S180) that the bearing is damaged, wherein the vibration signal of the bearing is detected in a predetermined detection section of a rotation angle of a crankshaft. [12] The method according to claim 11, wherein the method comprises: Defining the predetermined detection section separately for each cylinder based on the crankshaft rotation angle. [13] The method according to claim 11 or 12, wherein the method further comprises: Increasing (S150) a monitoring counter for each engine condition and Increasing (S170) a damage counter when the bearing vibration signal is greater than the predetermined damaged bearing threshold. [14] The method according to any one of claims 11 to 13, wherein the method comprises: Confirm (S180) the damage to the bearing when the increased monitoring counter is less than or equal to a predetermined damage-detecting accumulation monitoring counter.

Images