Electric tool and noise reduction system thereof

Abstract

The invention relates to an electric tool and a noise reduction system thereof.The electric tool comprises a shell, a motor at least partially contained in the shell, a control module electrically connected with the motor and a noise feedback module electrically connected with the control module, and the control module is used for monitoring the running state of the motor and generating a state signal; the electric tool has operation noise, the operation noise comprises a broadband noise signal and a narrowband noise signal, the noise feedback module comprises a noise control unit and a noise output unit, the noise control unit receives the state signal and outputs a corresponding digital signal, and the noise output unit outputs the digital signal to the electric tool. The noise output unit outputs a compiled noise signal according to the digital signal, and the compiled noise signal comprises a first noise signal superposed with the broadband noise signal and a second noise signal counteracting with the narrowband noise signal, so that the user experience is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a power tool and a noise reduction system thereof, in particular to a power tool and a noise reduction system thereof for improving user experience. BACKGROUND

[0002] At present, the power tools on the market more or less have running noise, which mainly comes from the fan and motor inside the power tool. ANC (Active Noise Cancellation) is usually adopted to suppress the running noise of the power tool. ANC needs to collect the noise source in real time through a microphone, then filter and invert through a processing chip, and finally play through a loudspeaker to achieve the noise reduction effect. The cost of the whole system is high, and the traditional ANC is only suitable for noise reduction of high frequency noise with a frequency range of 100-1000HZ. However, the sharp sound part of the running noise of the power tool needs to be eliminated, and its frequency is generally 2000-10000HZ, so the noise reduction effect is poor.

[0003] In view of the above problems, it is necessary to provide a power tool and a noise reduction system thereof to overcome the defects of the prior art. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide a power tool and a noise reduction system thereof. The technical solution adopted by the present application is as follows: a power tool, comprising a housing, a motor at least partially contained in the housing, a control module electrically connected to the motor, and a noise feedback module electrically connected to the control module, the control module is used for monitoring the running state of the motor and generating a state signal, the power tool has a running noise, the running noise includes a wide frequency noise signal and a narrow frequency noise signal; the noise feedback module includes a noise control unit and a noise output unit, the noise control unit receives the state signal and outputs a corresponding digital signal, the noise output unit outputs a compiled noise signal according to the digital signal, the compiled noise signal includes a first noise signal superimposed with the wide frequency noise signal and a second noise signal offset with the narrow frequency noise signal.

[0005] Further improvement is that the state signal includes a phase signal and a speed signal of the motor, the noise control unit includes a storage unit for storing the digital signal, and the noise control unit outputs the corresponding digital signal according to the phase signal and the speed signal.

[0006] Further improvement is that the frequency of the first noise signal is the same as the frequency of the wide frequency noise signal, and the first noise signal is the in-phase signal of the wide frequency noise signal.

[0007] Further improvement is that the second noise signal has the same frequency as the narrow-band noise signal, and the second noise signal is an inverse-phase signal of the narrow-band noise signal.

[0008] Further improvement is that the electric tool comprises a fan connected with the motor, and the noise output unit is connected with the shell and arranged close to the motor or the fan.

[0009] The present application solves the problems of the prior art by adopting the technical scheme of another aspect, which is a noise reduction system applied to an electric tool, the noise reduction system comprising:

[0010] a noise collection module, configured to collect operation noises of a plurality of electric tools and analyze the frequency spectrum of the operation noises, wherein the operation noises comprise wide-band noise signals and narrow-band noise signals;

[0011] a signal processing module, configured to generate corresponding compiled noise signals according to the wide-band noise signals and the narrow-band noise signals;

[0012] The electric tool comprises a motor, a control module electrically connected with the motor, and a noise feedback module electrically connected with the control module, wherein the control module is configured to monitor the operation state of the motor and generate a state signal, the noise feedback module comprises a noise control unit and a noise output unit, the noise control unit is configured to receive the state signal and output a corresponding digital signal, and the noise output unit is configured to output the compiled noise signals according to the digital signal, wherein the compiled noise signals comprise a first noise signal superimposed with the wide-band noise signals and a second noise signal counteracted with the narrow-band noise signals.

[0013] Further improvement is that the noise collection module comprises a data collection instrument configured to collect the operation noises, and a noise analysis unit electrically connected with the data collection instrument and configured to analyze the operation noises.

[0014] Further improvement is that the signal processing module comprises a signal generator configured to generate the compiled noise signals, a signal synthesizer configured to synthesize the compiled noise signals, and a signal compiler configured to compile the compiled noise signals into the digital signals.

[0015] Further improvement is that the noise control unit comprises a storage unit configured to store the digital signals, and the noise control unit is configured to extract the corresponding digital signals from the storage unit according to the state signal and transmit the digital signals to the noise output unit.

[0016] Further improvement scheme is that the amplitude of the first noise signal is superimposed with the wide frequency noise signal, the amplitude of the second noise signal is offset with the amplitude of the narrow frequency noise signal, and the amplitude of the second noise signal is less than or equal to the amplitude of the narrow frequency noise signal.

[0017] Compared with the prior art, the present application has the following beneficial effects: through the noise collection module of the noise reduction system, noise collection and analysis can be carried out offline, without real-time collection, and the running noise can be processed for noise reduction; secondly, the first noise signal output by the noise output unit can be superimposed with the wide frequency noise signal of the electric tool, so as to enhance the wind noise and meet the user's demand for the electric tool; in addition, the second noise signal output by the noise output unit can be offset with the narrow frequency noise signal of the electric tool, so as to achieve the effect of suppressing noise. BRIEF DESCRIPTION OF DRAWINGS

[0018] The specific embodiments of the present application will be further described in detail below in combination with the drawings:

[0019] Figure 1 It is a structural schematic diagram of the electric tool in the embodiment of the present application;

[0020] Figure 2 It is a partial sectional view of the electric tool in the second embodiment of the present application.

[0021] Figure 3 It is Figure 2 It is a partial sectional view of the noise output unit in the embodiment of the present application.

[0022] Figure 4 It is a noise signal spectrum curve diagram of the electric tool in the embodiment of the present application;

[0023] Figure 5 It is a spectrum curve comparison diagram of the electric tool before and after noise reduction in the embodiment of the present application;

[0024] Figure 6 It is a principle diagram of the noise reduction system in the embodiment of the present application;

[0025] Figure 7 It is a flow chart of the noise reduction system applied to the electric tool in the embodiment of the present application.

[0026] Meaning of reference signs in the drawings:

[0027] Power Tool (100, 100') Functional Module 101 Housing (10, 10') Motor (20, 20') Control Module 21 Fan (30, 30') Noise Feedback Module 40 Noise Control Unit 41 Noise Output Unit (42, 42', 42") Noise Reduction System 200 Noise Acquisition Module 210 Data Acquisition Unit 211 Noise Analysis Unit 212 Signal Processing Module 220 Signal Generator 221 Signal Synthesizer 222 Signal Compiler 223 Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0029] The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. For example, terms such as "upper," "lower," "front," and "rear" that indicate orientation or positional relationship are based solely on the orientation or positional relationship shown in the accompanying drawings and are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device / element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0030] Please see Figure 1 As shown, a preferred embodiment of the present invention relates to a power tool 100, specifically an axial flow hair dryer. The power tool 100 includes a housing 10, a motor 20 at least partially housed in the housing 10, a fan 30 located at the front end of the motor 20, a motor shaft connecting the motor and the fan, a motor support frame located between the fan and the motor, and a noise output unit 42 disposed on the motor support frame.

[0031] Figure 2 and Figure 3 A power tool 100' according to a second embodiment of the present invention is disclosed, specifically a centrifugal hair dryer. The power tool includes a housing 10', a motor 20' fixed to the housing, and a fan 30' connected to the motor. The motor includes a motor shaft, and the fan includes a hub connected to the motor shaft and fan blades extending from the hub. Figure 2 The location of the noise output unit 42' is revealed. The noise output unit is fixed inside the hub of the fan. In this embodiment, the noise output unit is arranged symmetrically with respect to the motor axis. Figure 3Another position of the noise output unit 42" is disclosed, which is symmetrically arranged on the outer side of the motor shell away from the fan. In the embodiment of the present application, the number of the noise output unit is not limited, and the noise output unit can be a loudspeaker. The noise output unit should be arranged around the main noise source. The running noise of the power tool is tested offline, and it is found that the main source of the running noise is the motor 20 and the fan 30. Therefore, the noise output unit 42 needs to be connected to the shell near the motor 20 or the fan 30, so that the running noise is strengthened or suppressed at the sound source.

[0032] The power tool in the embodiment of the present application generates running noise during operation, which includes wideband noise signals and narrowband noise signals. The wideband noise signals are generated by the high-speed flow of air in the duct of the blower, and the wideband noise signals are smooth wind noise, which is an acceptable running sound for users. The running sound can reflect the running state of the power tool and give users a strong operation experience to a certain extent. The narrowband noise signals are caused by high-order harmonics generated by the motor or fan in the blower. The narrowband noise signals are sharp and sharp, which is a relatively sharp sound signal. This sound signal can easily bring strong discomfort to users, which is the noise that needs to be suppressed by the noise reduction system applied to the power tool.

[0033] Figure 4 A power tool noise spectrum curve is disclosed, in which the abscissa represents the frequency (unit: HZ) of the noise signal, and the ordinate represents the sound pressure level (unit: dBA) of the noise signal. The sound pressure level is the intensity of sound. The intensity of sound perceived by the human ear is different for different frequencies of noise signals. Tests show that the full-band noise frequency range of the power tool is 20-20KHZ, and the full-band noise sound pressure level range is 0-90dBA. The wideband noise signal refers to a noise signal with a certain frequency width and continuous frequency. The difference between the sound pressure levels corresponding to the adjacent two frequencies is less than 15dBA. The narrowband noise signal refers to a noise signal distributed in a narrow frequency range and having a single frequency. The difference between the sound pressure levels corresponding to the adjacent two frequencies is greater than or equal to 15dBA. The greater the difference between the sound pressure levels of the narrowband noise signal and the surrounding noise signal, the more significant the noise.

[0034] The present application also aims to provide a noise reduction system 200 applied to a power tool, Figure 6 It is disclosed that the power tool 100 in the embodiment of the present application further comprises a control module 21 electrically connected to the motor 20 and a noise feedback module 40 electrically connected to the control module 21.

[0035] The control module 21 is used for monitoring the running state of the motor 20 and generating a state signal, the state signal including a phase signal and a rotating speed signal of the motor 20, the phase signal of the motor being consistent with the phase signal of the running noise of the electric tool.

[0036] The noise feedback module 40 includes a noise control unit 41 and a noise output unit 42 accommodated in a shell, the noise control unit 41 being configured as a separate structure fixed in the shell and connected with the control module 21 through a wire, or being directly welded to the control module 21 and constituting a functional module 101 with the control module 21, the noise output unit 42 being connected with the noise control unit 41 through a wire.

[0037] The noise control unit 41 receives the state signal and outputs a corresponding digital signal, and the noise output unit outputs a compiled noise signal according to the digital signal, the compiled noise signal including a first noise signal for superimposing with the wide-frequency noise signal and a second noise signal for canceling with the narrow-frequency noise signal.

[0038] The noise control unit 41 further includes a storage unit 411 for storing the compiled noise signal, the storage unit 411 being used for storing the compiled noise signal, the state signal output by the control module 21 being received by the noise control unit 41 and the noise control unit outputting a corresponding digital signal, the storage unit selectively outputting the compiled noise signal according to the digital signal, the compiled noise signal being output by the noise output unit 42 again, the noise output unit 42 on one hand outputting the first noise signal superimposed with the wide-frequency noise signal to achieve the effect of enhancing the wind noise and improving the user experience, and on the other hand outputting the second noise signal canceled with the narrow-frequency noise signal to cancel the narrow-frequency noise signal to achieve the effect of suppressing the noise.

[0039] The frequency of the first noise signal is the same as that of the wide-frequency noise signal, and the first noise signal is an in-phase signal of the wide-frequency noise signal. The frequency of the second noise signal is the same as that of the narrow-frequency noise signal, and the second noise signal is an anti-phase signal of the narrow-frequency noise signal. According to the principle of sound wave interference, sound waves have mutual interference effect in the transmission process, and when two sound waves with the same frequency, the same vibration direction and the same pace are emitted by the same sound source, interference phenomenon appears, if the two sound waves are in phase, the amplitude of the two superimposed waves increases and the sound pressure is enhanced, if the two sound waves are anti-phase, the amplitude of the two superimposed waves decreases and the sound pressure is weakened, and if the amplitudes of the two waves are the same, the two waves are completely canceled.

[0040] Figure 5The application discloses a comparison chart of frequency spectrum curves of an electric tool before and after noise reduction, wherein the solid line represents a noise signal frequency spectrum curve of the electric tool before noise reduction, the dotted line represents a noise signal frequency spectrum curve of the electric tool after noise reduction, the abscissa represents the frequency (unit: HZ) of the noise signal, the ordinate represents the sound pressure level (unit: dBA) of the noise signal, and also represents the amplitude of the noise signal. Since the first noise signal has the same frequency and in-phase as the wide-frequency noise signal, the amplitude of the first noise signal is designed to be greater than or equal to the amplitude of the wide-frequency noise signal, so that the first noise signal is superimposed on the wide-frequency noise signal to enhance the wind noise; since the second noise signal has the same frequency and opposite phase as the narrow-frequency noise signal, the amplitude of the second noise signal is designed to be less than or equal to the amplitude of the narrow-frequency noise signal, so that the second noise signal is cancelled with the narrow-frequency noise signal.

[0041] Figure 6 The application also discloses a noise reduction system 200 applied to the electric tool, wherein the noise reduction system 200 comprises a noise collection module 210, which is used for collecting operation noises of a plurality of electric tools and analyzing the frequency spectrum of the operation noises to obtain wide-frequency noise signals and narrow-frequency noise signals of the operation noises.

[0042] The noise collection module 210 comprises a data collection instrument 211 used for collecting the operation noises and a noise analysis unit 212 electrically connected with the data collection instrument 211 and used for analyzing the operation noises.

[0043] The signal processing module 220 generates corresponding compiled noise signals according to the wide-frequency noise signals and the narrow-frequency noise signals. The signal processing module 220 comprises a signal generator 221 used for generating the compiled noise signals, a signal synthesizer 222 used for synthesizing the compiled noise signals and a signal compiler 223 used for compiling the compiled noise signals into digital signals.

[0044] The signal generator 221 is specifically used for analogically generating a first noise signal superimposed on the wide-frequency noise signal and a second noise signal cancelled with the narrow-frequency noise signal; the signal synthesizer 222 is used for synthesizing the first noise signal and the second noise signal into a new noise signal; and the signal compiler 223 is used for compiling the new noise signal into a digital signal.

[0045] The electric tool 100 comprises a motor 20, a control module 21 electrically connected with the motor and a noise feedback module 40 electrically connected with the control module, the control module is used for monitoring the running state of the motor and generating a state signal, the noise feedback module comprises a noise control unit 41 and a noise output unit 42, the noise control unit 41 receives the state signal and outputs a corresponding digital signal, the noise output unit 42 outputs the compiled noise signal according to the digital signal, and the compiled noise signal comprises a first noise signal superimposed with the wide-frequency noise signal and a second noise signal counteracted with the narrow-frequency noise signal.

[0046] The working process of the noise reduction system will be further introduced below. Figure 7 The working process of the noise reduction system will be further introduced below.

[0047] S101: The acquisition instrument acquires the running noise of a plurality of electric tools and analyzes the running noise; first, 5-10 engineering prototypes are prepared and placed in an anechoic chamber or a semi-anechoic chamber, and a data acquisition instrument acquires the running noise of the electric tools; second, a noise analysis unit (which can be DASP software of Dongfangshe) analyzes the running noise to obtain a full-frequency noise spectrum of the running noise, mainly including a wide-frequency noise signal and a narrow-frequency noise signal.

[0048] S102: A signal generator simulates a first noise signal with the same frequency and phase as the wide-frequency noise signal and a second noise signal with the same frequency and opposite phase as the narrow-frequency noise signal.

[0049] S103: A signal synthesizer synthesizes the first noise signal and the second noise signal into one noise signal.

[0050] S104: A signal compiler converts the simulated and synthesized noise signal into a digital signal that can be recorded into a noise control unit.

[0051] S105: The digital signal compiled by the signal compiler is recorded into a storage unit of the noise control unit, the noise control unit receives a state signal of the control module electrically connected with the motor, the noise control unit extracts the corresponding digital signal from the storage unit according to the state signal and transmits the digital signal to the noise output unit, the noise output unit outputs a compiled noise signal according to the digital signal, the compiled noise signal comprises a first noise signal superimposed with the wide-frequency noise signal and a second noise signal counteracted with the narrow-frequency noise signal, so as to realize the strengthening of the wide-frequency noise signal and the suppression of the narrow-frequency noise signal, thereby meeting the pursuit of the user for the running noise of the electric tool while suppressing the sharp noise that is harmful to the user.

[0052] In addition, in the case of start-stop or insufficient voltage, the motor speed signal of the power tool in the embodiment of the present application will fluctuate, and for the noise generated under different speed conditions, the noise reduction system is also used for processing, first, the running noise under different speed conditions is collected offline and subjected to frequency spectrum analysis, then the corresponding compiled noise signal is obtained through the signal processing module, then the real-time speed signal and phase signal of the motor are obtained through the control module electrically connected with the motor, then the signal is transmitted to the noise control unit, the noise control unit outputs the corresponding compiled noise signal, and finally the corresponding compiled noise signal under different speed conditions is played through the noise output unit, including the anti-phase noise signal to offset the noise.

[0053] The present application is not limited to the above specific embodiments. Those skilled in the art can easily understand that the power tool and the noise reduction system applied to the power tool of the present application have many alternative solutions without departing from the principles and categories of the present application. The protection scope of the present application is subject to the content of the claims.

Claims

1. A power tool, comprising a housing, a motor at least partially housed in the housing, a control module electrically connected to the motor, and a noise feedback module electrically connected to the control module, the control module being used to monitor the operating status of the motor and generate a status signal, the power tool having operating noise, the operating noise including a broadband noise signal and a narrowband noise signal; characterized in that: The noise feedback module includes a noise control unit and a noise output unit. The noise control unit receives the status signal and outputs a corresponding digital signal. The noise output unit outputs a compiled noise signal based on the digital signal. The compiled noise signal includes a first noise signal superimposed on the broadband noise signal and a second noise signal canceled out by the narrowband noise signal.

2. The power tool according to claim 1, characterized in that: The status signal includes the phase signal and speed signal of the motor. The noise control unit includes a storage unit for storing the digital signal. The noise control unit outputs the corresponding digital signal based on the phase signal and the speed signal.

3. The power tool according to claim 1, characterized in that: The frequency of the first noise signal is the same as the frequency of the broadband noise signal, and the first noise signal is the in-phase signal of the broadband noise signal.

4. The power tool according to claim 1, characterized in that: The frequency of the second noise signal is the same as the frequency of the narrowband noise signal, and the second noise signal is the inverse phase signal of the narrowband noise signal.

5. The power tool according to claim 1, characterized in that: The power tool includes a fan connected to the motor, and the noise output unit is connected to the housing and disposed close to the motor or the fan.

6. A noise reduction system for power tools, characterized in that, The noise reduction system includes: A noise acquisition module is used to acquire the operating noise of several of the power tools and analyze the spectrum of the operating noise, wherein the operating noise includes wideband noise signals and narrowband noise signals; The signal processing module generates a corresponding compiler noise signal based on the wideband noise signal and the narrowband noise signal; The power tool includes a motor, a control module electrically connected to the motor, and a noise feedback module electrically connected to the control module. The control module is used to monitor the operating status of the motor and generate a status signal. The noise feedback module includes a noise control unit and a noise output unit. The noise control unit receives the status signal and outputs a corresponding digital signal. The noise output unit outputs a compiled noise signal based on the digital signal. The compiled noise signal includes a first noise signal superimposed on the broadband noise signal and a second noise signal canceled out by the narrowband noise signal.

7. The noise reduction system according to claim 6, characterized in that: The noise acquisition module includes a data acquisition instrument for acquiring the operating noise and a noise analysis unit electrically connected to the data acquisition instrument for analyzing the operating noise.

8. The noise reduction system according to claim 6, characterized in that: The signal processing module includes a signal generator for generating the compiled noise signal, a signal synthesizer for synthesizing the compiled noise signal, and a signal compiler for compiling the compiled noise signal into the digital signal.

9. The noise reduction system according to claim 6, characterized in that: The noise control unit includes a storage unit for storing the digital signal. The noise control unit extracts the corresponding digital signal from the storage unit according to the status signal and transmits it to the noise output unit.

10. The noise reduction system according to claim 6, characterized in that: The amplitude of the first noise signal is superimposed on the wideband noise signal, the amplitude of the second noise signal cancels out the amplitude of the narrowband noise signal, and the amplitude of the second noise signal is less than or equal to the amplitude of the narrowband noise signal.

Images