Fan control device, fan control method, and fan control program

Abstract

The present invention provides a fan control device that can control the fan speed so that it is less likely to be perceived as noise by people inside the vehicle. [Solution] A fan control device equipped with a processor controls a fan that cools an object to be cooled inside a vehicle, wherein the processor acquires ambient sound inside the vehicle picked up by a microphone installed inside the vehicle, performs frequency analysis on the acquired ambient sound to derive first analysis data, obtains second analysis data which varies depending on the fan rotation speed and is obtained by frequency analysis of the sound generated when the fan rotates, and determines an upper limit of the fan rotation speed based on the first analysis data and the second analysis data such that a first index, which is an index related to auditory perception of the ambient sound, satisfies a predetermined first condition.

Description

Technical Field

[0001] The present disclosure relates to a fan control device, a fan control method, and a fan control program for controlling a fan.

Background Art

[0002] Conventionally, an electronic device incorporating a cooling fan has been known. An example of this electronic device includes drive means for rotationally driving a fan, analysis means for analyzing frequencies with a high sound level in the vehicle interior space, calculation means for calculating the frequency of strong noise generated by the rotating fan, and setting means for setting the rotational speed of the fan based on the frequency of the strong noise calculated by the calculation means, and the drive means drives the fan at the rotational speed set by the setting means (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, the human sense of hearing is not considered. Therefore, controlling the rotational speed of the fan so that it is less likely to be perceived as noise by a person present in the vehicle interior is not considered.

[0005] The present disclosure provides a fan control device, a fan control method, and a fan control program that can control the rotational speed of a fan so that a person present in the vehicle interior is less likely to perceive it as noise.

Means for Solving the Problems

[0006] One aspect of the present disclosure is a fan control device comprising a processor for controlling a fan that cools an object to be cooled inside a vehicle, wherein the processor acquires ambient sound inside the vehicle picked up by a microphone installed inside the vehicle, performs frequency analysis on the acquired ambient sound to derive first analysis data, acquires second analysis data of fan sound which is sound generated when the fan rotates and varies according to the rotation speed of the fan, and determines an upper limit of the rotation speed of the fan based on the first analysis data and the second analysis data such that a first index, which is an index related to auditory perception of the ambient sound, satisfies a predetermined first condition.

[0007] One aspect of the present disclosure is a fan control method for controlling a fan that cools an object to be cooled inside a vehicle, comprising: acquiring ambient sound inside the vehicle picked up by a microphone installed inside the vehicle; deriving first analysis data by frequency analysis of the acquired ambient sound; acquiring second analysis data of fan sound, which is the sound generated when the fan rotates and which varies depending on the rotation speed of the fan; and determining an upper limit of the rotation speed of the fan based on the first analysis data and the second analysis data, such that a first index, which is an index related to auditory perception of the ambient sound, satisfies a predetermined first condition.

[0008] One aspect of this disclosure is a fan control program for causing a computer to execute the fan control method described above. [Effects of the Invention]

[0009] According to this disclosure, the fan speed can be controlled so that it is less likely to be perceived as noise by people inside the vehicle. [Brief explanation of the drawing]

[0010] [Figure 1] Block diagram showing an example of a fan control system according to this embodiment. [Figure 2] A diagram showing an example of an equal loudness level curve according to this embodiment. [Figure 3]This figure shows an example of the relationship between the fan speed, the fan noise frequency, and the generated noise according to this embodiment. [Figure 4] A diagram illustrating simultaneous masking according to this embodiment. [Figure 5] A diagram illustrating the time-dependent masking according to this embodiment. [Figure 6A] Flowchart (Part 1) showing an example of operation of the fan control device according to this embodiment. [Figure 6B] Flowchart (Part 2) showing an example of operation of the fan control device according to this embodiment. [Modes for carrying out the invention]

[0011] Hereinafter, embodiments specifically disclosing the fan control device, fan control method, and fan control program according to this disclosure will be described in detail with reference to the drawings as appropriate. However, unnecessarily detailed explanations may be omitted. For example, detailed explanations of already well-known matters and redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding by those skilled in the art. The accompanying drawings and the following explanation are provided to enable those skilled in the art to fully understand this disclosure and are not intended to limit the subject matter described in the claims.

[0012] (Knowledge that forms the basis of this disclosure) Patent Document 1 determines the fan speed by considering only the frequency of the strong noise generated by the fan and the audio level of ambient noise. However, it does not consider whether people actually inside the car perceive the noise generated by the fan as loud. Noise is composed of various frequency components. Furthermore, the sound pressure level of each frequency component of the sound does not necessarily correspond to the perceived loudness of each frequency component. In other words, a high sound pressure level does not necessarily mean that a person will perceive the sound as loud. Therefore, the determined fan speed may be excessive or insufficient.

[0013] The following embodiments describe a fan control device, a fan control method, and a fan control program that can control the fan speed so that it is less likely to be perceived as noise by people inside the vehicle.

[0014] (Embodiment) Figure 1 is a block diagram showing an example of a fan control system according to this embodiment.

[0015] The fan control system 1 comprises a fan control device 10, a microphone 20, a temperature sensor 30, and a fan 40. The fan control device 10, microphone 20, temperature sensor 30, and fan 40 are capable of communicating via a network. The network here may be, for example, a wired network, a wireless network, or a combination of a wired network and a wireless network. The wired network may include at least one of the following: wired LAN, wired WAN, or power line communication, and may also be other network configurations capable of wired communication. LAN stands for Local Area Network. WAN stands for Wide Area Network. Power line communication is also written as PLC. PLC stands for Power Line Communication. The wireless network may include at least one of the following: wireless LAN such as Wi-Fi (registered trademark), wireless WAN, or mobile cellular communication network such as 4G or 5G, and may also be other network configurations capable of wireless communication. The fan 40 may be controlled by the fan control device 10 by changing the supply voltage or by PWM control.

[0016] The fan control device 10 includes a processor 11, memory 12, and a communication device 13.

[0017] The processor 11 includes a frequency spectrum analysis unit 111, an audio level comparison unit 112, and a fan rotation speed control unit 113. The processor 11 is configured using a CPU, DSP, or FPGA, etc. The CPU is the abbreviation of Central Processing Unit. The DSP is a Digital Signal Processor. The FPGA is the abbreviation of Field Programmable Gate Array. The processor 11 does not necessarily have to include the frequency spectrum analysis unit 111, the audio level comparison unit 112, and the fan rotation speed control unit 113. For example, by the processor 11 executing the fan control program stored in the memory 12, each function as the frequency spectrum analysis unit 111, the audio level comparison unit 112, and the fan rotation speed control unit 113 may be executed.

[0018] The frequency spectrum analysis unit 111 acquires data of the ambient sound inside the vehicle picked up using the microphone 20 installed inside the vehicle. The frequency spectrum analysis unit 111 performs frequency analysis on the ambient sound data. Specifically, the frequency spectrum analysis unit 111 analyzes the sound pressure level for each frequency of the ambient sound data and derives the analysis data as frequency spectrum data. The ambient sound includes, for example, the driving noise of the vehicle, the sound of wind from the vehicle's air conditioner, the music reproduced and output as sound, etc. Note that the frequency spectrum data regarding the picked-up ambient sound is also referred to as ambient sound analysis data.

[0019] The voice level comparison unit 112 acquires frequency spectrum data for each rotation speed of the sound generated during the rotation of the recorded fan 40 stored in the memory 12. Note that the sound generated during the rotation of the fan 40 is also referred to as fan sound. The frequency spectrum data is data indicating the sound pressure level for each frequency. The frequency spectrum data is, for example, data obtained by frequency analyzing a sound previously recorded by the microphone 20 in an environment of a vehicle similar to the vehicle on which the cooling target is mounted. Note that the vehicle during recording is placed in, for example, a quiet acoustic environment so that only the fan sound is recorded as much as possible. Note that the frequency spectrum data regarding the fan sound held in the memory 12 is also referred to as fan sound analysis data. The voice level comparison unit 112 compares the fan sound analysis data with the ambient sound analysis data. Note that the frequency analysis of the fan sound analysis data may be performed by the processor 11, or data obtained by performing the analysis by another device may be acquired.

[0020] The fan rotation speed control unit 113 determines the upper limit of the rotation speed of the fan 40 based on the fan sound analysis data and the ambient sound analysis data so that a first index related to the sound perception of the fan sound satisfies a predetermined first condition. In other words, the fan rotation speed control unit 113 determines the upper limit of the rotation speed of the fan 40 within a range that does not affect the sound perception based on the comparison result of the voice level comparison unit 112 comparing the fan sound analysis data with the ambient sound analysis data. The fan rotation speed control unit 113 controls the rotation speed of the fan 40 so that it is below the determined upper limit. For example, the fan rotation speed control unit 113 controls the rotation speed with the upper limit of the rotation speed of the fan 40 as the target rotation speed, thereby suppressing the fan sound from being annoying and increasing the cooling performance of the fan 40.

[0021] The range that affects hearing is the range of sound pressure levels that a person perceives as loud. Conversely, the range that does not affect hearing is the range of sound pressure levels that a person does not perceive as loud. The range that affects hearing can be defined by an index related to hearing. For example, the range that affects hearing is the range of sound pressure levels that are greater than the auditory threshold. For example, the range that does not affect hearing is the range of sound pressure levels that are below the auditory threshold. The auditory threshold is a threshold related to hearing, and may be, for example, 40 phons, or any value between 20 phons and 40 phons, for example, 30 phons.

[0022] Furthermore, the fan speed control unit 113 may acquire information on the temperature of the object to be cooled, measured by the temperature sensor 30. The fan speed control unit 113 may determine the upper limit of the fan speed of the fan 40 based on the temperature of the object to be cooled. For example, if the temperature of the object to be cooled is above a predetermined temperature threshold, the fan speed control unit 113 may increase the upper limit of the fan speed of the fan 40. If the temperature of the object to be cooled is below the temperature threshold, the upper limit of the fan speed of the fan 40 may not be changed, or may be reduced. As a result, the fan control device 10 can increase the upper limit of the fan speed only when the object to be cooled is hot, thereby reducing the load on the processor 11 while cooling the object to be cooled to the desired state.

[0023] Each process performed by processor 11 may be executed by a single processor or distributed among multiple processors. For example, the processor 11 that performs the processing for realizing the functions of the frequency spectrum analysis unit 111 and the audio level comparison unit 112 may be a different processor from the processor 11 that performs the processing for realizing the functions of the fan speed control unit 113.

[0024] Memory 12 includes ROM and RAM. ROM stands for Read Only Memory. RAM stands for Random Access Memory. ROM stores programs that define the processing (or operation) of the processor 11, particularly the fan rotation control program and the data referenced when that program is executed. RAM is work memory used when the processor 11 performs processing and operations, and temporarily stores data or information generated or acquired in each process.

[0025] Memory 12, for example, pre-stores fan noise analysis data. Furthermore, fan noise analysis data may be acquired from an external device and temporarily stored in Memory 12. Memory 12 may also store information about rules for defining simultaneous masking ranges and time-dependent masking ranges, as described later.

[0026] The communication device 13 communicates with other terminals in the vehicle and the fan control system 1, the microphone 20, the temperature sensor 30, and the fan 40 via the network shown in Figure 1, enabling the transmission and reception of data.

[0027] Microphone 20 picks up ambient sounds inside the vehicle. Microphone 20 is, for example, a microphone installed inside the vehicle. Microphone 20 is, for example, a microphone mounted in the vehicle for hands-free operation or voice recognition.

[0028] The temperature sensor 30 measures the temperature of the object to be cooled. The temperature sensor 30 is, for example, a thermistor or a thermal diode. Note that the temperature sensor 30 is not essential, and it may not be provided. The temperature sensor 30 may be placed, for example, near the object to be cooled or inside the object to be cooled.

[0029] The fan 40 cools the object to be cooled by blowing air. The object to be cooled may be, for example, a semiconductor such as a central control unit in a vehicle. The object to be cooled may also be, for example, an SoC (System on a Chip), an audio amplifier, a power supply unit, or a user-provided device such as a smartphone. The object to be cooled may also be something other than a semiconductor that easily generates heat. The fan 40 may be installed, for example, near or above the object to be cooled.

[0030] Next, I will explain the indicators related to human hearing.

[0031] First, let's explain the equal-loudness level curves.

[0032] Figure 2 shows an example of an equal-loudness level curve according to this embodiment. In Figure 2, the horizontal axis represents frequency, and the vertical axis represents sound pressure level. Figure 2 shows an equal-loudness level curve in accordance with the ISO 226:2003 standard.

[0033] Equal loudness level curves represent frequency characteristics obtained by connecting sound pressure levels at which sounds of various frequencies are perceived as having the same loudness. In other words, equal loudness level curves can also be called equal sensitivity curves, which represent the basic frequency sensitivity characteristics of hearing, and are one of the most fundamental characteristics of hearing. The term "auditory" is also referred to as "auditory sensory" or "auditory perception."

[0034] As shown in Figure 2, even at the same sound pressure level, the perception of sound by human hearing can differ depending on the frequency. For example, according to Figure 2, the lower the frequency, the less likely people are to perceive a sound as "loud" even at a high sound pressure level, while the higher the frequency, the more likely people are to perceive a sound as "loud" even at a low sound pressure level. For example, if a value between 20 phon and 40 phon, such as 30 phon, is set as the auditory threshold for what people perceive as "loud" or "not loud," it can be seen that the acceptable sound pressure level changes depending on the frequency.

[0035] Figure 3 shows an example of the relationship between the rotational speed of the fan 40 according to this embodiment, the frequency of the fan noise, and the sound pressure level of the generated noise.

[0036] Figure 3 shows fan noise analysis data, specifically the sound pressure levels of pre-recorded fan noise at different frequencies. In Figure 3, the horizontal axis represents frequency, and the vertical axis represents the sound pressure level of the fan noise. As shown in Figure 3, the higher the rotational speed, the larger the peak in the graph shown in Figure 3, indicating a higher sound pressure level.

[0037] The processor 11, for example, refers to the equal loudness level curves in Figure 2 and the fan noise analysis data in Figure 3 to determine whether the fan noise is perceived as "loud" or "not loud" at each frequency, and determines the upper limit of the fan speed 40 according to the determination result. In this case, the processor 11 may determine the upper limit of the fan speed 40 such that the sound pressure level of the fan noise analysis data is lower than the sound pressure level of the ambient noise analysis data at each frequency that affects hearing. For example, within a range that does not affect hearing, the processor 11 may increase the upper limit of the fan speed 40 as the sound pressure level of the sound component is higher than the audible threshold at frequencies of sound components included in the ambient noise, and decrease the upper limit of the fan speed 40 as the sound pressure level of the sound component is lower. As a result, the fan control device 10 can adjust the amount of change in rotation speed at each frequency according to the loudness of the ambient noise, so that the fan noise is perceived as "not loud". Here, the first indicator is the sound pressure level of the ambient sound, i.e., the ambient sound analysis data at a first frequency that affects auditory perception. Furthermore, the first condition is that the sound pressure level of the fan noise at the frequency that affects auditory perception is lower than the sound pressure level of the ambient sound at the first frequency.

[0038] Furthermore, while this example illustrates the extraction of frequencies that affect auditory perception based on equal-loudness level curves and fan noise analysis data, it is not limited to this. The processor 11 may also extract frequencies that affect auditory perception based on equal-loudness level curves and ambient noise analysis data.

[0039] Next, let's discuss auditory masking. Auditory masking refers to the reduction in the perception of one sound due to the presence of another sound. Examples of auditory masking include simultaneous masking and temporal masking.

[0040] First, let me explain simultaneous masking. Figure 4 is a diagram illustrating simultaneous masking according to this embodiment. In Figure 4, the horizontal axis represents the sound frequency, and the vertical axis represents the sound pressure level.

[0041] Simultaneous masking occurs when ambient noise and fan noise occur simultaneously. Simultaneous masking is related to the dynamic behavior of the cochlear basilar membrane. It occurs when membrane vibrations generated by a sound normally detected in a quiet environment are masked by vibrations generated by another sound, specifically a sound with a sufficient sound pressure level and a frequency sufficiently close to that of the first sound. Simultaneous masking is also called spectral masking or frequency masking.

[0042] When an ambient sound SD1 occurs as shown in Figure 4, sounds that fall within the simultaneous masking range R1 are indistinguishable from ambient sound SD1 by auditory perception; in other words, they are inaudible to the listener. The simultaneous masking range R1 is the range of frequencies and sound pressure levels that are simultaneously masked, with ambient sound SD1 as the reference. On the other hand, sounds that do not fall within the simultaneous masking range R1 are indistinguishable from ambient sound SD1 by auditory perception; in other words, they are inaudible to the listener. That is, the closer a sound is to the frequency of ambient sound SD1, the less audible it is to the listener due to the simultaneous masking effect. The simultaneous masking range R1 is larger at higher frequencies than at lower frequencies relative to the frequency of ambient sound SD1. This is because the masking effect is stronger at higher frequencies relative to ambient sound SD1.

[0043] The range within the simultaneous masking range R1 is an example of a range that does not affect auditory perception. The set of frequency and sound pressure level combinations that constitute the contour of the simultaneous masking range R1 is an example of an auditory threshold. The shape and size of the simultaneous masking range R1 are examples and depend on the frequency and sound pressure level of the ambient sound being masked, so other shapes and sizes are possible. The simultaneous masking range R1 indicates the range of frequencies and sound pressure levels of the sound that the ambient sound masks, depending on the frequency and sound pressure level of the ambient sound. The simultaneous masking range R1 is an example of the first indicator. The fact that the fan sound falls within the simultaneous masking range R1 is an example of the first condition.

[0044] As a specific example, as shown in Figure 4, suppose that ambient sound SD1 is generated simultaneously with fan sounds SD2 and SD3, which have different frequencies from ambient sound SD1. In this case, fan sound SD2 falls within the simultaneous masking range R1 and is masked. Fan sound SD3 does not fall within the simultaneous masking range R1 and at least a portion of it is not masked. The masked fan sound SD2 has no effect on auditory perception. The unmasked fan sound SD3 may have an effect on auditory perception.

[0045] The processor 11 determines the simultaneous masking range R1 based on the frequency and sound pressure level of the ambient sound SD1. In this case, for example, the memory 12 may pre-store information on rules for generating the simultaneous masking range according to the frequency and sound pressure level of the ambient sound SD1. The processor 11 may determine the simultaneous masking range R1 based on this rule information stored in the memory 12.

[0046] The processor 11 may determine an upper limit for the rotational speed of the fan 40 based on the fan noise analysis data corresponding to the rotational speed shown in Figure 3 and the simultaneous masking range R1. In this case, the processor 11 may determine the upper limit for the rotational speed so that the fan noise is included in the simultaneous masking range R1. In other words, the processor 11 may determine the upper limit for the rotational speed so that the sound pressure level of the fan noise at frequencies included in the simultaneous masking range R1 is less than or equal to the maximum sound pressure level inside the simultaneous masking range R1.

[0047] Thus, the processor 11 may determine a simultaneous masking range R1 that indicates the range of frequencies and sound pressure levels in which the fan noise generated simultaneously with the ambient noise SD1 is masked, depending on the frequency and sound pressure level of the ambient noise SD1. The processor 11 may also determine an upper limit on the rotation speed of the fan 40 so that the fan noise falls within the simultaneous masking range R1.

[0048] Next, I will explain time-dependent masking. Figure 5 is a diagram illustrating the time-dependent masking according to this embodiment. In Figure 5, the horizontal axis represents time, and the vertical axis represents the sound pressure level.

[0049] Temporal masking occurs between sounds that are consecutive in time. As an example of temporal masking, fan noise occurring before or after the occurrence of ambient noise may be masked. The example shown in Figure 5 illustrates the masking of fan noise occurring after the occurrence of ambient noise. Temporal masking can occur when the time difference between two sounds is up to 200ms. For example, the processor 11 may determine that masking occurs if the time difference between the two sounds is below a time threshold, for example, 100ms or less. Note that temporal masking does not depend on the frequency of the ambient noise that occurs.

[0050] When an ambient sound SD11 occurs as shown in Figure 5, sounds that fall within the temporal masking range R2 are indistinguishable from the ambient sound SD11 by auditory perception; in other words, they are inaudible to the listener. The temporal masking range R2 is the range of time and sound pressure level within which the ambient sound SD11 is masked over time. On the other hand, sounds that do not fall within the temporal masking range R2 are indistinguishable from the ambient sound SD11 by auditory perception; in other words, they are inaudible to the listener. That is, the closer a sound is to the ambient sound SD11 in terms of when it occurs, the less audible it becomes to the listener due to the temporal masking effect.

[0051] The range within the temporal masking range R2 is an example of a range that does not affect hearing. The set of time and sound pressure level combinations that constitute the contour of the temporal masking range R2 is an example of a hearing threshold. The shape of the temporal masking range R2 is, for example, rectangular. The maximum sound pressure level of the temporal masking range R2 is, for example, the same sound pressure level as ambient sound SD11. The temporal masking range R2 indicates the range of occurrence time and sound pressure level in which sounds that occur after the occurrence of ambient sound are masked, depending on the occurrence time and sound pressure level of the ambient sound. The temporal masking range R2 is an example of the first indicator. The fact that the fan sound falls within the temporal masking range R2 is an example of the first condition.

[0052] As a specific example, as shown in Figure 5, suppose that fan noises SD12 and SD13, which have different frequencies from ambient noise SD11, are generated simultaneously. In this case, fan noise SD12 falls within the time-dependent masking range R2 and is masked. Fan noise SD13 does not fall within the time-dependent masking range R2 and at least a portion of it is not masked. The masked fan noise SD12 has no effect on auditory perception. The unmasked fan noise SD13 may have an effect on auditory perception.

[0053] The processor 11 determines the time-dependent masking range R2 based on the occurrence time and sound pressure level of the ambient sound SD1. In this case, for example, the memory 12 may pre-store information on rules for generating a time-dependent masking range according to the occurrence time and sound pressure level of the ambient sound SD11. The processor 11 may determine the time-dependent masking range R2 based on this rule information stored in the memory 12.

[0054] The processor 11 may determine an upper limit on the rotational speed based on the fan noise analysis data corresponding to the rotational speed shown in Figure 3 and the time-dependent masking range R2. In this case, the processor 11 may determine the upper limit on the rotational speed so that the fan noise is included in the time-dependent masking range R2. In other words, the processor 11 may determine the upper limit on the rotational speed so that the sound pressure level of the fan noise at frequencies included in the time-dependent masking range R2 is less than or equal to the maximum sound pressure level inside the simultaneous masking range R1.

[0055] Thus, the processor 11 may determine a time-dependent masking range R2 that indicates the range of occurrence times and sound pressure levels in which fan noise generated after the occurrence of ambient noise SD11 is masked, depending on the occurrence time and sound pressure level of ambient noise SD11. The processor 11 may also determine an upper limit for the rotation speed of the fan 40 so that the fan noise falls within the time-dependent masking range R2.

[0056] Next, an example of the operation of the fan control device 10 will be described. Figures 6A and 6B are flowcharts showing examples of the operation of the fan control device 10.

[0057] The fan control device 10 controls the fan 40 that cools the cooling target inside the vehicle. This example of operation may be performed in a different order of processing unless there are specific constraints. This example of operation is preferably executed by the processor 11. More specifically, it may be executed by the processor 11 executing a fan control program stored in memory 12.

[0058] Furthermore, the fan control device 10 may periodically execute the processes shown in Figures 6A and 6B, for example, every 20ms. At this time, each time the processes shown in Figures 6A and 6B are executed, the processor 11 measures the processing time, for example, using a timer, and derives the sound pressure level of the ambient sound. This processing time can also be said to be the time when the ambient sound occurred during the processing shown in Figures 6A and 6B. The processor 11 stores the information of the ambient sound occurrence time and sound pressure level in the memory 12. The ambient sound occurrence time and sound pressure level stored in the memory may be used in processing related to time-dependent masking during processing after the processing in which the ambient sound occurrence time and sound pressure level were obtained.

[0059] First, in step ST1, ambient sounds inside the vehicle are collected using a microphone 20 installed inside the vehicle. The processor 11 acquires the ambient sounds collected by the microphone 20.

[0060] In step ST2, the processor 11 analyzes the sound pressure level at each frequency by analyzing the frequency spectrum of the acquired ambient sound and derives ambient sound analysis data. Also in step ST2, the processor 11 analyzes and extracts the frequencies of the ambient sound that have an effect on auditory perception in the equal loudness level curve, based on the ambient sound analysis data. Frequencies that have an effect on auditory perception are frequencies at which auditory sensitivity exceeds the auditory threshold, for example, frequencies where the ambient sound exceeds 40 phon.

[0061] In step ST3, the processor 11 obtains fan noise analysis data from, for example, memory 12. Based on the ambient noise analysis data and the fan noise analysis data, the processor 11 sets the rotation speed of the fan 40 so that the sound pressure level for each frequency that affects hearing does not affect hearing.

[0062] In step ST2, the processor 11 may acquire fan noise analysis data from memory 12 and, based on the fan noise analysis data, analyze and extract the frequencies of the fan noise that have an effect on hearing in the equal loudness level curve. In that case, in step ST3, the processor 11 may analyze the sound pressure level at each frequency by frequency spectrum analysis of the acquired ambient noise and derive ambient noise analysis data. In that case as well, in step ST3, the processor 11 may set the rotation speed of the fan 40 so that the sound pressure level at each frequency that has an effect on hearing does not affect hearing, based on the ambient noise analysis data and the fan noise analysis data.

[0063] In step ST4, the processor 11 assumes a rotational speed higher than the current rotational speed of the fan 40. The current rotational speed of the fan may be, for example, a rotational speed command value from the vehicle or a rotational speed detected by a rotational speed sensor (not shown). For example, if the current rotational speed of the fan 40 is 1000 rpm, the processor 11 assumes the rotational speed is 2000 rpm or 3000 rpm. Also in step ST4, the processor 11 compares the fan noise analysis data for the assumed rotational speed with the ambient noise analysis data at each frequency in terms of sound pressure level.

[0064] Furthermore, the sound collection by the microphone 20 shown in step ST1, the frequency spectrum analysis shown in step ST2, the setting of the fan speed 40 shown in step ST3, and the comparison of the fan noise and ambient noise shown in step ST4 are all performed within a time-dependent masking range R2, for example, within 20ms.

[0065] In step ST5, the processor 11 determines, based on the comparison, whether the sound pressure level of each frequency in the ambient sound analysis data is greater than the sound pressure level of each frequency in the fan sound analysis data for the assumed rotational speed.

[0066] In step ST6, if step ST5 is Yes, that is, if the ambient noise has a higher sound pressure level than the fan noise at each frequency, the processor 11 determines whether the assumed rotational speed is the maximum rotational speed of the fan 40 (ST6).

[0067] If step ST6 is Yes, that is, if the assumed rotation speed is the maximum rotation speed of fan 40, then processor 11 proceeds to step ST13.

[0068] If step ST6 is No, that is, if the assumed rotational speed is not the maximum rotational speed of fan 40, the processor 11 proceeds to step ST4. Then, the processor 11 assumes a rotational speed higher than the currently assumed rotational speed for fan 40.

[0069] On the other hand, if step ST5 is No, that is, if the ambient sound is less than or equal to the sound pressure level of the fan sound at at least one of the frequencies, the processor 11 proceeds to step ST7. That is, if the sound pressure level of each frequency of the ambient sound analysis data is less than or equal to the sound pressure level of each frequency of the fan sound analysis data for the assumed rotational speed at at least one of the frequencies, the processor 11 proceeds to step ST7.

[0070] In step ST7, the processor 11 compares the fan noise, i.e., the fan noise analysis data, for the assumed rotational speed, i.e., the rotational speed assumed in the final step ST4, with the ambient noise, i.e., the ambient noise analysis data, taking simultaneous masking into consideration. Specifically, the processor 11 determines the simultaneous masking range R1 based on the frequency and sound pressure level of the ambient noise included in the ambient noise analysis data. The processor 11 compares the maximum sound pressure level of each frequency that falls within the simultaneous masking range R1 with the sound pressure data of the same frequency in the fan noise analysis data for the assumed rotational speed.

[0071] In step ST8, the processor 11 determines whether the maximum sound pressure level for each frequency that falls within the simultaneous masking range R1 based on the ambient sound analysis data is greater than the sound pressure data for the same frequency in the fan sound analysis data for the assumed rotational speed.

[0072] In step ST9, if step ST8 is Yes, that is, if the sound pressure level of the ambient sound is higher than that of the fan sound at each frequency when simultaneous masking is taken into consideration, the processor 11 determines whether the assumed rotation speed is the maximum rotation speed of the fan 40. In other words, if the maximum sound pressure level of each frequency that falls within the simultaneous masking range R1 based on the ambient sound analysis data is greater than the sound pressure data for the same frequency in the fan sound analysis data for the assumed rotation speed, the processor 11 determines whether the assumed rotation speed is the maximum rotation speed of the fan 40.

[0073] If step ST9 is Yes, meaning the assumed rotation speed is the maximum rotation speed of fan 40, proceed to step ST13.

[0074] If step ST9 is No, that is, if the assumed rotational speed is not the maximum rotational speed of fan 40, proceed to step ST7. Then, processor 11 assumes a rotational speed for fan 40 that is higher than the currently assumed rotational speed.

[0075] On the other hand, if step ST8 is No, that is, if simultaneous masking is taken into account, and at least one of the frequencies the ambient sound is less than or equal to the sound pressure level of the fan sound, the processor 11 proceeds to step ST10. In other words, for at least one of the frequencies that fall within the simultaneous masking range R1 based on the ambient sound analysis data, if the maximum sound pressure level of each frequency is less than or equal to the sound pressure data for the same frequency in the fan sound analysis data for the assumed rotational speed, the processor 11 proceeds to step ST10.

[0076] In step ST10, the processor 11 compares the fan noise, i.e., the fan noise analysis data, for the assumed rotational speed, i.e., the rotational speed assumed in the final step ST7, with the ambient noise, i.e., the ambient noise analysis data, taking time-series masking into consideration. Specifically, the processor 11 determines the time-series masking range R2 based on the occurrence time and sound pressure level of the ambient noise included in the ambient noise analysis data. In this case, the time-series masking range R2 to be used for the current execution of the processing in Figures 6A and 6B is determined based on the occurrence time and sound pressure level of the ambient noise held in memory 12 during previous executions of the processing in Figures 6A and 6B. Then, if the current time, i.e., the time of the current processing of Figures 6A and 6B, is inside the time-series masking range R2, the processor 11 compares the maximum sound pressure level that falls inside the time-series masking range R2 with the maximum sound pressure level among the sound pressure levels of each frequency in the fan noise analysis data for the assumed rotational speed.

[0077] In step ST11, the processor 11 determines, based on the comparison, whether the current time is within the time-series masking range R2, and whether the maximum sound pressure level that falls within the time-series masking range R2 is greater than the maximum sound pressure level among the sound pressure levels of each frequency in the fan noise analysis data for the assumed rotational speed.

[0078] In step ST12, if step ST11 is Yes, that is, if the ambient noise has a higher sound pressure level than the fan noise when considering time-dependent masking, the processor 11 determines whether the assumed rotational speed is the maximum rotational speed of the fan 40. In other words, if the current time is inside the time-dependent masking range R2, and the maximum sound pressure level that falls inside the time-dependent masking range R2 is greater than the maximum sound pressure level among the sound pressure levels of each frequency in the fan noise analysis data for the assumed rotational speed, the processor 11 determines whether the assumed rotational speed is the maximum rotational speed of the fan 40.

[0079] If step ST12 is Yes, that is, if the assumed rotation speed is the maximum rotation speed of fan 40, proceed to step ST13.

[0080] If step ST12 is No, that is, if the assumed rotational speed is not the maximum rotational speed of fan 40, the process proceeds to step ST10. Then, processor 11 assumes a rotational speed higher than the currently assumed rotational speed for fan 40.

[0081] On the other hand, if step ST11 is No, that is, if the sound pressure level of ambient noise is less than or equal to the sound pressure level of fan noise when considering time-dependent masking, the processor 11 proceeds to step ST13. In other words, if the current time is inside the time-dependent masking range R2, and the maximum sound pressure level that falls inside the time-dependent masking range R2 is less than or equal to the maximum sound pressure level among the sound pressure levels of each frequency in the fan noise analysis data for the assumed rotational speed, the processor 11 proceeds to step ST13.

[0082] In step ST13, the processor 11 determines and sets the assumed rotational speed at this point as the maximum allowable rotational speed, i.e., the upper limit of the fan 40's rotational speed. If the fan 40's rotational speed at this point is greater than or equal to the maximum allowable rotational speed, the processor 11 changes the fan 40's rotational speed to be equal to the maximum allowable rotational speed.

[0083] Step ST14 determines whether or not the rotation of fan 40 will end. For example, it is determined that the rotation of fan 40 will end if the rotation period of fan 40 has ended, or if an instruction has been given to stop the rotation of fan 40.

[0084] If step ST14 is Yes, that is, if the fan 40 has stopped rotating, the processor 11 terminates the processes shown in Figures 6A and 6B. On the other hand, if step ST14 is No, that is, if the fan 40 has not stopped rotating, the processor 11 proceeds to step ST1 and executes the processes shown in Figures 6A and 6B again.

[0085] Thus, in steps ST4 to ST6, the fan control device 10 repeatedly compares the ambient sound without considering auditory masking with the fan sound corresponding to the rotation speed and makes assumptions about the rotation speed, taking auditory perception into account, until the sound pressure of the ambient sound exceeds the sound pressure of the fan sound. In steps ST7 to ST9, the fan control device 10 repeatedly compares the ambient sound considering simultaneous masking with the fan sound corresponding to the rotation speed and makes assumptions about the rotation speed, taking auditory perception into account, until the sound pressure of the ambient sound exceeds the sound pressure of the fan sound. In steps ST10 to ST12, the fan control device 10 repeatedly compares the ambient sound considering time-dependent masking with the fan sound corresponding to the rotation speed and makes assumptions about the rotation speed, taking auditory perception into account, until the sound pressure of the ambient sound exceeds the sound pressure of the fan sound. It is not essential that all three of these series of processes be performed; at least one series of processes is sufficient. However, by performing all of these series of processes, the fan control device 10 can further improve the accuracy of determining the upper limit of the rotation speed.

[0086] Furthermore, the fan control device 10 may periodically perform the processes shown in Figures 6A and 6B, for example, every 20ms. This allows the fan control device 10 to suitably determine the upper limit of the rotation speed even when the ambient noise inside the vehicle changes. In addition, the fan control device 10 can perform processing that takes into account time-dependent masking, assuming a different time point than the processing points shown in Figures 6A and 6B.

[0087] As described above, the fan control device 10 of this embodiment analyzes the fan noise and ambient noise, taking into account human hearing, and determines whether the fan noise is perceived as being lower than or equal to the ambient noise, thereby controlling the upper limit of the fan speed 40. The fan control device 10 can increase the fan speed 40 within a range where the ambient noise does not become louder than the fan noise, taking into account various situations that do not affect hearing. The fan control device 10 approaches the upper limit of the fan speed 40's physical maximum rotational speed within a range that does not affect hearing. For example, if the ambient noise is loud, the fan control device 10 can increase the rotational speed further, thereby improving the cooling performance of the fan 40.

[0088] Furthermore, even if the ambient noise changes, the fan control device 10 can quickly lower the upper limit of the fan speed of the fan 40 by periodically performing the flow shown in Figures 6A and 6B. As a result, the fan control device 10 can also quickly reduce the actual rotation speed of the fan 40.

[0089] The processor 11 controls the fan noise to be quieter than ambient noise within the human audible range, for example, 20Hz to 20kHz, but this is not limited to outside the audible range. Outside the audible range, the processor 11 may control the fan noise to be slightly louder than ambient noise.

[0090] Although various embodiments have been described above with reference to the drawings, it goes without saying that this disclosure is not limited to such examples. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of this disclosure. Furthermore, the components of the above embodiments may be combined in any way without departing from the spirit of the invention.

[0091] (Note) Based on the descriptions of the embodiments described above, the following technologies are disclosed.

[0092] (Technology 1) A fan control device equipped with a processor that controls a fan for cooling an object inside a vehicle, The aforementioned processor, The ambient sound inside the vehicle, picked up by a microphone installed inside the vehicle, is acquired. The acquired ambient sound is subjected to frequency analysis to derive the first analysis data. The fan noise, which is the sound generated when the fan rotates and varies depending on the fan's rotation speed, is analyzed at a frequency to obtain second analysis data. Based on the first analysis data and the second analysis data, the upper limit of the fan's rotation speed is determined such that the first indicator, which is an indicator related to auditory perception of the ambient sound, satisfies a predetermined first condition. Fan control device.

[0093] The processor is, for example, processor 11. The fan is, for example, fan 40. The fan control device is, for example, fan control device 10. The microphone is, for example, microphone 20. The first analysis data is, for example, ambient sound analysis data. The second analysis data is, for example, fan sound analysis data. The first threshold is, for example, the auditory threshold.

[0094] This allows the fan control system to adjust the fan speed in a way that is less audibly noisy to people inside the vehicle, while still effectively cooling the object being cooled.

[0095] (Technology 2) The processor increases the upper limit of the rotational speed as the sound pressure level of the ambient noise increases, and decreases the upper limit of the rotational speed as the sound pressure level of the ambient noise decreases. The fan control device described in (Technical 1).

[0096] This allows the fan control system to set a higher rotation speed when ambient noise is loud, thereby improving cooling performance. Conversely, the fan control system can also set a lower rotation speed when ambient noise is loud, reducing the noise perceived by people inside the vehicle.

[0097] (Technology 3) The aforementioned processor, Based on the isosensitivity curves showing the frequency sensitivity characteristics of hearing and the second analysis data, a first frequency is extracted which is the frequency at which the fan sound becomes louder than the first threshold. Based on the first and second analysis data, the sound pressure level of the fan noise at the first frequency is less than the sound pressure level of the ambient noise at the first frequency. A fan control device as described in either (Technology 1) or (Technology 2).

[0098] An example of an equal-sensitivity curve is an equal-loudness level curve.

[0099] This allows the fan control device to identify the frequency range in the fan noise that humans perceive as loud, and by reducing the sound pressure level of the fan noise at this frequency compared to ambient noise, it can suppress the perception of the fan noise as noise.

[0100] (Technology 4) The aforementioned processor, Based on the isosensitivity curves showing the frequency sensitivity characteristics of hearing and the first analysis data, a first frequency is extracted which is the frequency at which the ambient sound becomes louder than a first threshold. The first indicator is the sound pressure level of the ambient sound at the first frequency, The first condition is that the sound pressure level of the fan noise at the first frequency is less than the sound pressure level of the ambient noise at the first frequency. A fan control device as described in (Technology 1) or (Technology 2).

[0101] This allows the fan control device to identify frequencies in the ambient noise that humans perceive as loud, and by reducing the sound pressure level of the fan noise to less than that of the ambient noise at these frequencies, it can suppress the perception of the fan noise as noise.

[0102] (Technology 5) The aforementioned processor, Based on the acquired frequency and sound pressure level of the ambient sound, a first masking range is determined as the first index, which indicates the range of frequencies and sound pressure levels of sounds that the ambient sound will mask. The first condition is that the fan noise falls within the first masking range. A fan control device as described in any one of (Technology 1) to (Technology 4).

[0103] The first masking range is, for example, the simultaneous masking range R1.

[0104] This allows the fan control device to control the fan speed within a range that does not affect the perceived sound, taking simultaneous masking into account.

[0105] (Technology 6) The aforementioned processor, Based on the acquired generation time and sound pressure level of the ambient sound, a second masking range is determined as the first index, which indicates the range of generation times and sound pressure levels in which sounds generated after the ambient sound are masked. The first condition is that the fan noise falls within the second masking range. A fan control device as described in any one of (Technology 1) to (Technology 5).

[0106] The second masking range is, for example, the time-dependent masking range R2.

[0107] This allows the fan control device to control the fan speed within a range that does not affect the perceived sound, taking into account masking over time.

[0108] (Technology 7) The aforementioned processor, The temperature information of the object to be cooled is obtained, If the temperature is above the second threshold, the upper limit of the fan's rotation speed is increased. A fan control device as described in any one of (Technology 1) to (Technology 6).

[0109] The second threshold is, for example, a temperature threshold.

[0110] This allows the fan control unit to increase the fan speed, for example, only when the temperature of the object being cooled is high. Thus, the fan control unit can ensure the necessary cooling performance while reducing the processing load on the fan control unit itself.

[0111] (Technology 8) A fan control method for controlling a fan that cools an object to be cooled inside a vehicle, The ambient sound inside the vehicle, picked up by a microphone installed inside the vehicle, is acquired. The acquired ambient sound is subjected to frequency analysis to derive the first analysis data. The fan noise, which is the sound generated when the fan rotates and varies depending on the fan's rotation speed, is analyzed at a frequency to obtain second analysis data. Based on the first and second analysis data, the upper limit of the fan's rotation speed is determined so that the auditory performance index falls within a first threshold range. Fan control method.

[0112] This allows the fan control method to achieve the same effect as technique 1.

[0113] (Technology 7) A fan control program that causes a computer to execute the fan control method described in Technical 6.

[0114] As a result, the fan control program achieves the same effect as in Technique 1. [Industrial applicability]

[0115] This disclosure is useful as a fan control device, fan control method, and fan control program, etc., that can control the rotation speed of a fan so that it is less likely to be perceived as noise by people inside a vehicle. [Explanation of symbols]

[0116] 1. Fan control system 10 Fan control unit 11 processors 111 Frequency Spectrum Analysis Unit 112 Audio level comparison section 113 Fan speed control unit 12 memory 121 Frequency Spectrum Data 13 Communication devices 20 microphones 30 Temperature Sensors 40 Fans

Claims

1. A fan control device equipped with a processor that controls a fan for cooling an object inside a vehicle, The aforementioned processor, The ambient sound inside the vehicle, picked up by a microphone installed inside the vehicle, is acquired. The acquired ambient sound is subjected to frequency analysis to derive the first analysis data. The fan noise, which is the sound generated when the fan rotates and varies depending on the fan's rotation speed, is analyzed at a frequency to obtain second analysis data. Based on the first analysis data and the second analysis data, the upper limit of the fan's rotation speed is determined such that the first index, which is an index related to auditory perception of the ambient sound, satisfies a predetermined first condition. Fan control device.

2. The processor increases the upper limit of the rotational speed as the sound pressure level of the ambient noise increases, and decreases the upper limit of the rotational speed as the sound pressure level of the ambient noise decreases. The fan control device according to claim 1.

3. The aforementioned processor, Based on the isosensitivity curves showing the frequency sensitivity characteristics of hearing and the second analysis data, a first frequency is extracted which is the frequency at which the fan sound becomes louder than the first threshold. The first indicator is the sound pressure level of the ambient sound at the first frequency, The first condition is that the sound pressure level of the fan noise at the first frequency is less than the sound pressure level of the ambient noise at the first frequency. The fan control device according to claim 1 or 2.

4. The aforementioned processor, Based on the isosensitivity curves showing the frequency sensitivity characteristics of hearing and the first analysis data, a first frequency is extracted which is the frequency at which the ambient sound becomes greater than a first threshold. The first indicator is the sound pressure level of the ambient sound at the first frequency, The first condition is that the sound pressure level of the fan noise at the first frequency is less than the sound pressure level of the ambient noise at the first frequency. The fan control device according to claim 1 or 2.

5. The aforementioned processor, Based on the acquired frequency and sound pressure level of the ambient sound, a first masking range is determined as the first index, which indicates the range of frequencies and sound pressure levels of sounds that the ambient sound will mask. The first condition is that the fan noise falls within the first masking range. The fan control device according to claim 1 or 2.

6. The aforementioned processor, Based on the acquired generation time and sound pressure level of the ambient sound, a second masking range is determined as the first index, which indicates the range of generation times and sound pressure levels in which sounds generated after the ambient sound are masked. The first condition is that the fan noise falls within the second masking range. The fan control device according to claim 1 or 2.

7. The aforementioned processor, The temperature information of the object to be cooled is obtained, If the temperature is above the second threshold, the upper limit of the fan's rotation speed is increased. The fan control device according to claim 1 or 2.

8. A fan control method for controlling a fan that cools an object to be cooled inside a vehicle, The ambient sound inside the vehicle, picked up by a microphone installed inside the vehicle, is acquired. The acquired ambient sound is subjected to frequency analysis to derive the first analysis data. The fan noise, which is the sound generated when the fan rotates and varies depending on the fan's rotation speed, is analyzed at a frequency to obtain second analysis data. Based on the first analysis data and the second analysis data, the upper limit of the fan's rotation speed is determined such that the first index, which is an index related to auditory perception of the ambient sound, satisfies a predetermined first condition. Fan control method.

9. A fan control program that causes a computer to execute the fan control method described in claim 8.

Images