Abnormal noise diagnostic device

Abstract

The present invention provides an abnormal noise diagnostic device that accurately detects abnormal noises associated with normal combustion from among the abnormal noises emitted from an engine. [Solution] The abnormal noise diagnostic device 20 includes an information acquisition unit 21 that acquires engine information 15 including the number of cylinders of the engine 5, rotational speed information 13 indicating the rotational speed of the engine 5, and engine sound information 14 indicating the engine sound of the engine 5; a combustion timing calculation unit 22 that calculates the combustion timing of the engine 5 based on the engine information 15 and rotational speed information 13; an abnormal noise acquisition unit 23 that detects abnormal noises contained in the engine sound based on the engine sound information 14 and acquires the frequency and timing of occurrence of the abnormal noises; and a determination unit 24 that determines that abnormal noises whose frequency is at a specific frequency and whose timing of occurrence is the same as the combustion timing are abnormal noises associated with normal combustion.

Description

Technical Field

[0001] The present disclosure relates to a abnormal noise diagnosis device for diagnosing abnormal noises generated from an engine.

Background Art

[0002] As an abnormal noise emitted from an in-vehicle engine or the like, a knocking sound caused by knocking is known. Since knocking occurs during abnormal combustion in the combustion chamber, it is important for diagnosing the operating state of the engine. Patent Document 1 discloses a technique for determining whether a knocking sound is included in an abnormal noise generated from an engine.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, an abnormal noise caused by combustion excitation force, so-called rattling sound, has a different event from knocking, and thus its frequency and occurrence timing are also different from those of knocking. Further, it is not caused by abnormal combustion in the combustion chamber like knocking, but is an abnormal noise generated along with normal combustion. Therefore, it is required to accurately detect an abnormal noise accompanying normal combustion from the abnormal noises emitted from the engine.

Means for Solving the Problems

[0005] An abnormal noise diagnostic device that solves the above problems includes: an information acquisition unit that acquires engine information including the number of cylinders of the engine, rotational speed information indicating the rotational speed of the engine, and engine sound information indicating the engine sound of the engine; a combustion timing calculation unit that calculates the combustion timing of the engine based on the engine information and the rotational speed information; an abnormal noise acquisition unit that detects abnormal noises contained in the engine sound based on the engine sound information and acquires the frequency and timing of occurrence of the abnormal noises; and a determination unit that determines that an abnormal noise whose frequency is at a specific frequency and whose timing of occurrence is the same as the combustion timing is an abnormal noise associated with normal combustion. [Effects of the Invention]

[0006] According to this disclosure, it is possible to accurately detect abnormal noises associated with normal combustion from among the abnormal noises emitted from the engine. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a block diagram showing a schematic configuration of an abnormal sound diagnostic system, including one embodiment of an abnormal sound diagnostic device. [Figure 2] Figure 2 is a flowchart showing an example of the abnormal sound diagnostic process performed by the abnormal sound diagnostic device. [Figure 3] Figure 3 is a graph showing an example of the relationship between time and the level of abnormal noise at a specific frequency. [Modes for carrying out the invention]

[0008] An embodiment of the abnormal noise diagnostic device will be described with reference to Figures 1 to 3. As shown in Figure 1, the abnormal noise diagnosis system 10 diagnoses the engine noise emitted from the engine 5. The abnormal noise diagnosis system 10 includes a sensor 11, an engine noise measuring instrument 12, and an abnormal noise diagnosis device 20.

[0009] Sensor 11 detects the rotational speed of engine 5. More specifically, sensor 11 detects the rotational angle of the crankshaft of engine 5 relative to the top dead center of the reference cylinder. The information indicating the detection result of sensor 11 is called rotational speed information 13. Rotational speed information 13 is information that associates the rotational angle of the crankshaft with time.

[0010] The engine sound measuring device 12 measures the engine sound emitted by the engine 5. The engine sound measuring device 12 is composed of, for example, a microphone. The information showing the measurement results of the engine sound measuring device 12 is called engine sound information 14. The engine sound information 14 is information that associates the volume level of the engine sound with time. The measurement of engine sound by the engine sound measuring device 12 starts at the same time as the detection of rotational speed by the sensor 11.

[0011] (Abnormal noise diagnostic device) The abnormal sound diagnostic device 20 is primarily composed of an information processing device. This information processing device includes a communication device, an input device, a display device, a storage device, a processor, and the like. Note that this hardware configuration is just an example, and other hardware configurations may be included.

[0012] A communication device is an interface that transmits and receives data by establishing a communication path with other devices. An input device is a device that receives input from a user or other party. Examples of input devices include a mouse and a keyboard. A display device is a display or touch panel that displays various information. A storage device is a storage device that stores data and programs for executing various functions. Examples of storage devices include ROM (Read Only Memory), RAM (Random Access Memory), and hard disks.

[0013] A processor controls various processes using programs and data stored in memory. Examples of processors include CPUs (Central Processing Units) and MPUs (Micro Processor Units). This processor executes various processes corresponding to various tasks by loading programs stored in ROM (ROM, etc.) into RAM (RAM). For example, when a specific application program is launched, the processor runs the processes that execute each task.

[0014] A processor is not limited to performing all of its operations through software processing. For example, a processor may have dedicated hardware circuits (e.g., application-specific integrated circuits: ASICs) that perform hardware processing for at least some of the operations it performs.

[0015] A processor includes the CPU and memory such as RAM and ROM. Memory stores program code or instructions configured to cause the CPU to perform processing. Memory, or non-temporary computer-readable media, includes any available media accessible by a general-purpose or dedicated computer.

[0016] The abnormal noise diagnostic device 20 has an information acquisition unit 21, a combustion timing calculation unit 22, an abnormal noise acquisition unit 23, and a determination unit 24 as functional units that operate by program execution. The information acquisition unit 21 acquires various types of information. In addition to rotational speed information 13 and engine sound information 14, the information acquisition unit 21 acquires engine information 15. The engine information 15 is information relating to the main specifications of the engine 5, and includes the number of cylinders of the engine 5.

[0017] The combustion timing calculation unit 22 calculates the combustion timing of the engine 5. The combustion timing calculation unit 22 calculates the combustion timing of the engine 5 based on the rotational speed information 13 and the engine information 15. Specifically, the combustion timing calculation unit 22 calculates the top dead center of the reference cylinder as one combustion timing, and calculates the rotation angle corresponding to the number of cylinders of the engine 5 as other combustion timings.

[0018] The abnormal sound acquisition unit 23 detects an abnormal sound included in the engine sound based on the engine sound information 14 and the rotational speed information 13, and acquires the frequency and occurrence timing of the detected abnormal sound. Specifically, the abnormal sound acquisition unit 23 acquires a spectrogram of the engine sound by performing a short-time Fourier transform on the engine sound information 14. The abnormal sound acquisition unit 23 detects, as an abnormal sound, a region where the abnormal sound level, which is the integrated value of the volume level in the abnormal sound frequency band, exceeds a threshold value based on the spectrogram. Then, the abnormal sound acquisition unit 23 acquires the frequency and occurrence timing of the detected abnormal sound.

[0019] The determination unit 24 determines whether the abnormal sound detected by the abnormal sound acquisition unit 23 is a combustion accompanied by normal combustion. Specifically, the determination unit 24 determines an abnormal sound whose frequency is at a specific frequency and whose occurrence timing is the same as the combustion timing as an abnormal sound accompanied by normal combustion. The specific frequency is one of the abnormal sound frequency bands and is in the range of 1 kHz to 2 kHz. The specific frequency is the frequency of an abnormal sound (rattling sound) caused by combustion excitation force, that is, an abnormal sound generated during normal combustion.

[0020] (Abnormal sound diagnosis process) Referring to FIG. 2, the abnormal sound diagnosis process executed by the abnormal sound diagnosis device 20 will be described. In the abnormal sound diagnosis process, an abnormal sound included in the engine sound is detected, and it is determined whether the abnormal sound is an abnormal sound accompanied by normal combustion or another abnormal sound that is not an abnormal sound accompanied by normal combustion.

[0021] As shown in FIG. 2, the abnormal noise diagnostic device 20 first acquires various types of information (step S101). In step S101, the information acquisition unit 21 acquires the rotational speed information 13, the engine sound information 14, and the engine information 15.

[0022] Next, the abnormal noise diagnostic device 20 acquires an abnormal noise (step S102). In step S102, the abnormal noise acquisition unit 23 acquires the frequency and the occurrence timing of the abnormal noise detected based on the engine information.

[0023] Next, the abnormal noise diagnostic device 20 determines the frequency of the abnormal noise acquired by the abnormal noise acquisition unit 23 (step S103). In step S103, the determination unit 24 determines whether the frequency of the abnormal noise is within 1 kHz to 2 kHz (specific frequency). The determination unit 24 holds the abnormal noise with a frequency within 1 kHz to 2 kHz (step S103: YES) as the object of the final determination.

[0024] Next, the abnormal noise diagnostic device 20 calculates the combustion timing (step S104). In step S104, the combustion timing calculation unit 22 calculates the combustion timing based on the engine information 15 and the rotational speed information 13.

[0025] After calculating the combustion timing, the abnormal noise diagnostic device 20 performs timing comparison (step S105). In step S105, the determination unit 24 compares the combustion timing with the occurrence timing of the abnormal noise at the specific frequency. When the combustion timing and the occurrence timing are the same (step S105: YES), the determination unit 24 determines that the abnormal noise is an abnormal noise accompanying normal combustion (step S106), and ends the series of processes.

[0026] On the other hand, for the abnormal noise whose frequency is not within 1 kHz to 2 kHz (step S103: NO) and the abnormal noise with a deviation between the occurrence timing and the combustion timing (step S105: NO), the determination unit 24 determines that they are other abnormal noises that are not abnormal noises accompanying normal combustion (step S107), and ends the series of processes. The abnormal noise diagnostic device 20 displays the result of the abnormal noise diagnosis process on a display device or the like.

[0027] (Effect of the embodiment) Figure 3 is a graph showing an example of the relationship between time and abnormal noise levels at specific frequencies (1kHz to 2kHz). Times t1, t2, t3, t4, t5, and t6 represent combustion timings.

[0028] As shown in Figure 3, the abnormal noise diagnostic device 20 diagnoses abnormal noises that occur at times t1 and t4, when their occurrence timing coincides with the combustion timing, as abnormal noises associated with normal combustion. The operation and effects of this embodiment will now be described.

[0029] (1) As shown in Figure 3, abnormal noises associated with normal combustion occur irregularly. In this regard, the abnormal noise diagnostic device 20 acquires engine information 15 including the number of cylinders of the engine 5, rotational speed information 13 detected by the sensor 11, and engine sound information 14 indicating the engine sound. The abnormal noise diagnostic device 20 calculates the combustion timing of the engine and acquires the frequency and timing of occurrence of abnormal noises included in the engine sound. The abnormal noise diagnostic device 20 then determines that abnormal noises whose frequency is at a specific frequency and whose timing of occurrence is the same as the combustion timing are abnormal noises associated with normal combustion.

[0030] With this configuration, it is possible to distinguish and detect abnormal noises associated with abnormal combustion, such as knocking, from abnormal noises associated with normal combustion. As a result, abnormal noises associated with normal combustion can be detected with high accuracy.

[0031] (Other embodiments) This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0032] The abnormal noise diagnostic device 20 may be configured to include at least one of the sensor 11 and the engine noise measuring device 12. [Explanation of symbols]

[0033] 5...Engine, 10...Abnormal noise diagnostic system, 11...Sensor, 12...Engine sound measuring instrument, 13...Rotation speed information, 14...Engine sound information, 15...Engine information, 20...Abnormal noise diagnostic device, 21...Information acquisition unit, 22...Combustion timing calculation unit, 23...Abnormal noise acquisition unit, 24...Determination unit.

Claims

[Claim 1] An information acquisition unit that acquires engine information including the number of cylinders of the engine, rotational speed information indicating the rotational speed of the engine, and engine sound information indicating the engine sound of the engine, A combustion timing calculation unit calculates the combustion timing of the engine based on the engine information and the rotational speed information, An abnormal noise acquisition unit detects abnormal noises contained in the engine noise based on the engine noise information and acquires the frequency and timing of occurrence of the abnormal noises. The system includes a determination unit that determines that an abnormal noise whose frequency is at a specific frequency and whose occurrence timing is the same as the combustion timing is an abnormal noise associated with normal combustion. A device for diagnosing abnormal noises.

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