JP2008256228A - Silencer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silencer capable of effectively eliminating driving noise generated in an object device while effectively utilizing a space. <P>SOLUTION: A duct member 101 is disposed in a state of vertically extending along a back face of a vending machine 1 and communicating with an exhaust opening 20 at its lower end portion. A first microphone 102A and a speaker 103 are disposed in the dust member 101, and the sound from the speaker 103 input to the first microphone 102A produces a sound signal of opposite phase to the driving noise generated in the vending machine 1 and input to the first microphone 102A, so that the sound from the speaker 103 is interfered with the driving noise. Thus, the driving noise generated in the vending machine 1 can be effectively eliminated by effectively utilizing the space by disposing the components in the space of a comparatively small depth formed at the back side of the vending machine 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a silencer, and more particularly to a silencer for silencing drive sound generated from a target device such as a vending machine.

  Usually, a vending machine that accommodates merchandise such as beverages is provided with a cooling device for cooling the merchandise. This cooling device generally includes a cooler for cooling the air in the machine, a compressor for compressing refrigerant supplied to the cooler, a condenser for liquefying the compressed refrigerant, and a compressor or condenser. A fan that is rotationally driven to cool the air is provided.

  In the casing of this type of vending machine, for example, a merchandise accommodating portion for accommodating merchandise is formed from the central portion to the upper portion, and the cooling device is disposed in the lower portion in the casing. Normally, the lower part of the housing has an air inlet on the front and an air outlet on the back. When the blower is driven, air outside the machine is sucked in from the air inlet and around the compressor and condenser. Through the exhaust port.

  Although such air intakes and exhausts are indispensable for circulating outside air into the machine, the driving sound generated from the various components provided in the casing as described above is There was a problem of leakage from the mouth. Therefore, when such a vending machine is installed indoors in a quiet place such as a hotel or a hospital, the problem of noise may become serious.

In order to solve such a problem, conventionally, a technique has been proposed in which a drive sound is prevented from leaking from within the apparatus by providing a muffling member (for example, Patent Document 1).
JP 2003-281613 A

  However, when the muffling member is used, although a sound with a high frequency can be satisfactorily muffled, there is a problem that it is difficult to mute a sound with a low frequency. In particular, the drive sound generated from the compressor or the blower has a relatively low frequency, and there are cases where the sound cannot be sufficiently silenced even if a silencer member is used. Therefore, it is conceivable to provide a silencer in the case of the vending machine to mute the drive sound generated in the case. However, it is often difficult to secure a large space in the case. was there.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a silencer that can effectively silence a drive sound generated by a target device by effectively using a space.

  A silencer according to a first aspect of the present invention is provided so as to extend in the vertical direction along the back surface of the target device, and a duct member communicating with an opening formed in the back surface at one end portion in the vertical direction; A first microphone that is provided in a member and receives a drive sound that enters the duct member from the target device through the opening; a sound signal generating unit that generates a sound signal; and the first microphone in the duct member. A speaker provided at a position closer to the opening than the one microphone relative to the opening and outputting a sound based on the sound signal generated by the sound signal generating means, wherein the sound signal generating means comprises the first A sound signal is generated so that sound from the speaker input to one microphone has an opposite phase to the driving sound input to the first microphone.

  According to such a configuration, the sound signal is generated so that the sound from the speaker input to the first microphone has an opposite phase to the drive sound generated by the target device input to the first microphone. Thus, it is possible to cause the sound from the speaker to interfere with the driving sound and to mute the driving sound. That is, the sound output from the speaker has an opposite phase to the drive sound generated by the target device at the position reaching the microphone, and the drive sound is muted by sound wave interference. Accordingly, the drive sound generated by the target device using the silencer member or the like is not passively silenced, but the drive sound can be silenced by actively generating a sound having a phase corresponding to the drive sound. . In this way, by adopting a configuration that silences the drive sound using sound wave interference, unlike the configuration that uses the silencer member, the drive sound generated by the target device can be effectively silenced. it can.

  Normally, a target device such as a vending machine is installed with its back face facing a wall surface. At this time, a predetermined space is formed between the back surface and the wall surface of the target device. According to the configuration of the present invention, by providing the first microphone and the speaker on the duct member extending in the vertical direction along the back surface of the target device, each depth is formed in a space with a relatively small depth formed on the back side of the target device. By disposing the parts, it is possible to mute the driving sound that has entered the duct member from the target device through the opening. Therefore, it is possible to mute the drive sound generated by the target device by effectively using the space.

  In addition to the above configuration, the silencer according to the second aspect of the present invention is configured such that the sound signal generation means generates a sound signal based on an input signal from the first microphone. According to such a configuration, the drive sound generated in the target device by the feedback control is muted based on the input signal from the first microphone provided at a position farther in the vertical direction with respect to the opening than the speaker. be able to.

  A silencer according to a third aspect of the present invention, in addition to the above-described configuration, is provided at a position closer to the opening than the speaker in the duct member in the vertical direction, and from the target device through the opening. A second microphone to which drive sound that has entered the duct member is input is provided, and the sound signal generating means is configured to generate a sound signal based on an input signal from the second microphone. According to such a configuration, the drive sound generated in the target device by the feedforward control is muted based on the input signal from the second microphone provided closer to the opening than the speaker in the vertical direction. can do.

  In particular, when a duct member is provided on the back surface of a target device that is long in the vertical direction, such as a vending machine, the duct member can be formed longer in the vertical direction, so the second microphone and the speaker provided in the duct member. Can be made longer. Thus, if the distance between the second microphone and the speaker is made longer, the drive sound muffling process by the feedforward control can be performed better.

  A silencer according to a fourth aspect of the present invention is configured by opening the back surface of the duct member in addition to the above configuration. According to such a configuration, by installing the target device so that the duct member whose back surface is open contacts the wall surface, the back surface of the duct member can be configured by the wall surface, thereby further reducing the manufacturing cost. can do.

  According to the present invention, by generating the sound signal so that the sound from the speaker input to the first microphone has an opposite phase to the drive sound generated by the target device input to the first microphone. Since the sound from the speaker can be interfered with the driving sound and the driving sound can be silenced, the driving sound generated by the target device can be effectively silenced. In addition, since each part is arranged in a space formed on the back side of the target device with a relatively small depth, the drive sound that has entered the duct member from the target device through the opening can be silenced. The drive sound generated by the target device can be silenced by effectively using the space.

Embodiment 1 FIG.
1A and 1B are diagrams showing a configuration example of a vending machine 1 to which a silencer 100 according to Embodiment 1 of the present invention is applied. FIG. 1A is a front view, and FIG. 1B is a side view. Yes. FIG. 2 is a front view showing a state in which the open / close door 3 of the vending machine 1 of FIG. 1 is opened. FIG. 3 is a schematic sectional side view of the vending machine 1 of FIG. FIG. 4 is a perspective view of the vending machine 1 of FIG. 1 as viewed from the back side. This vending machine 1 is a vending machine that sells beverages and the like enclosed in cans as commodities, and stores a large number of commodities in a casing 2 having a vertically long rectangular parallelepiped shape. In the following, the left side in FIG. 1B will be described as the front, the right side as the rear, the near side as the right side, and the back side as the left side.

  A front opening 2 </ b> A that opens the entire front surface is formed on the front surface of the housing 2, and the front opening 2 </ b> A is covered with an opening / closing door 3 that is attached to the housing 2 so as to be opened and closed. That is, the open / close door 3 forms the front surface of the housing 2 in a closed state. Legs 4 are attached to the four corners on the bottom surface of the housing 2. These leg portions 4 are screwed into the bottom surface of the housing 2 so as to be able to advance and retract in the vertical direction. When installing the vending machine 1, the height of the housing 2 relative to the ground is adjusted by adjusting the screwing amount of each leg 4 to the housing 2 and grounding the bottom surface of each leg 4. be able to.

  In the center of the front surface of the open / close door 3, a money insertion area 5 is formed that is used when a user who wants to purchase goods inserts money. In this money insertion area 5, a coin insertion slot 5A for inserting coins, a bill insertion slot 5B for inserting banknotes, and a return lever 5C for instructing the return of the inserted coins are inserted. And an input amount display portion 5D for displaying the total amount of money. When the return lever 5C is operated after the coin is inserted, the bill is returned from the bill input port 5B, and the coin is returned from the coin return port 6 formed in the lower part of the open / close door 3.

  A display area 7 on which samples of products that can be sold by the vending machine 1 are displayed is formed in the upper front portion of the open / close door 3. This display area 7 is provided with a purchase button 7A associated with each sample displayed, and after the user inserts money from the coin insertion slot 5A or the bill insertion slot 5B, By operating the purchase button 7A, it is possible to instruct purchase of a product corresponding to the purchase button 7A. The product for which purchase is instructed is sent out to the lower part in the housing 2 and can be taken out from a horizontally long product outlet 8 formed in the lower part of the door 3. In addition, when the amount of the product instructed to be purchased is lower than the input amount, the change corresponding to the difference is returned from the coin return slot 6.

  A money processing unit 9 is provided at a position corresponding to the back side of the money insertion area 5 on the front side of the central portion of the rear surface of the open / close door 3. The money handling unit 9 stores a money inserted from the coin insertion slot 5A and the bill insertion slot 5B, and performs a process for returning the money from the coin return slot 6 or the bill insertion slot 5B as necessary. It is. A control unit 10 is provided on the side of the money processing unit 9 in the center of the back surface of the open / close door 3, and the operation of the vending machine 1 is controlled by a processor provided in the control unit 10. ing.

  In the housing 2, a product storage portion 11 for storing products is formed in a region extending from the center to the top, and a cooling device 12 for cooling the products in the product storage portion 11 is provided in the housing 2. Located at the bottom inside. The product storage unit 11 is formed by arranging a cooling product storage unit 11 </ b> A and a heated product storage unit 11 </ b> B each having a vertically long shape side by side. A cooler 13 for cooling the air in the cooled product housing portion 11A is disposed below the cooled product housing portion 11A. On the other hand, the heater 14 for heating the air in the said heated goods accommodating part 11B is arrange | positioned under the heated goods accommodating part 11B. A product discharge port 15 for discharging a product from the product storage unit 11 to the product outlet 8 side is formed on the front side in the casing 2. A plurality of product discharge ports 15 are formed, and each product discharge port 15 is associated with the cooled product storage unit 11A or the heated product storage unit 11B.

  The cooling device 12 is for cooling the product accommodated in the cooled product accommodating portion 11A. In addition to the cooler 13, the compressor 16 that compresses the refrigerant supplied to the cooler 13 is compressed. A condenser 17 that liquefies the refrigerant and a blower 18 that is rotationally driven to cool the compressor 16 and the condenser 17 are provided. The compressor 16 is rotationally driven by an AC motor to which an AC voltage is supplied. On the other hand, the blower 18 is rotationally driven by a DC motor to which a DC voltage is supplied.

  The cooler 13, the compressor 16, and the condenser 17 communicate with each other via piping, and cool the air in the cooled product storage portion 11 </ b> A via the cooler 13 by circulating the refrigerant through these portions. can do. More specifically, when the cooling device 12 is driven, the refrigerant is compressed by the compressor 16 to become high-pressure gas, and is then liquefied by being cooled by the condenser 17. Then, the liquefied refrigerant is decompressed and evaporated in the cooler 13, whereby the cooler 13 is cooled by so-called latent heat of vaporization. The liquefied refrigerant is compressed again by the compressor 16 and circulated to the condenser 17 and the cooler 13.

  At the bottom of the open / close door 3, a horizontally long intake port 19 is formed in which both end portions are located in the vicinity of both left and right end portions of the open / close door 3. On the other hand, a horizontally long exhaust port 20 is formed at the bottom of the rear surface of the housing 2 so that at least a part thereof faces the intake port 19 in the front-rear direction. A partition plate 21 is provided below the product storage portion 11 in the housing 2, and a region below the partition plate 21 has an intake port 19 and an exhaust port 20 as openings, and the inside of the housing 2. A duct-like space 22 penetrating in the front-rear direction is formed.

  Among the components of the cooling device 12, the condenser 17, the blower 18, and the compressor 16 are disposed in the duct-like space 22. More specifically, the condenser 17, the blower 18, and the compressor 16 are arranged in this order in the front-rear direction at the bottom of the housing 2. Thereby, the condenser 17, the blower 18, and the compressor 16 are opposed to the intake port 19 and the exhaust port 20 in the front-rear direction, respectively. On the other hand, the cooler 13 is disposed above the duct-shaped space 22.

  When the cooling device 12 is driven, the blower 18 is driven to rotate, so that air outside the machine is sent into the machine through the air inlet 19. The air sent into the machine passes around the condenser 17 and the compressor 16 in the duct-like space 22 and is sent out of the machine through the exhaust port 20, whereby the condenser 17 and the compressor 16 are cooled. The

  A silencer 100 is provided at the lower part of the back surface of the housing 2 so as to cover the exhaust port 20. The silencer 100 is a device for muting the drive sound generated by the vending machine 1 serving as the target device, and the drive sound that travels backward from the cooling device 12 in the housing 2 passes through the exhaust port 20. Then, it enters the silencer 100 and is silenced in the silencer 100. Here, the silencer 100 is provided with a first microphone 102A, a second microphone 102B, and a speaker 103 attached to the duct member 101 in addition to the duct member 101 communicating with the exhaust port 20.

  The duct member 101 has a rectangular parallelepiped shape that is thin in the front-rear direction in which the left and right widths and the top and bottom heights are larger than the front and rear thicknesses, and a hollow member having an open front surface and an upper surface is attached to the rear surface of the housing 2. Is configured. Accordingly, the front surface of the duct member 101 is formed by the back surface of the housing 2, and a duct-like space 104 extending in the vertical direction along the back surface of the housing 2 is formed inside the duct member 101. The duct-like space 104 has a lower end communicating with the duct-like space 22 in the housing 2 via the exhaust port 20, thereby extending the duct-like space 22 upward from the exhaust port 20. The upper end of the duct member 101 is open to the outside from the opening 101A formed at the upper end of the duct member 101.

  The duct member 101 is disposed such that the center portion in the left-right direction faces the center portion in the left-right direction of the exhaust port 20. A first microphone 102 </ b> A is attached to an upper end portion of the back surface of the duct member 101 at the center portion in the left-right direction. On the other hand, a second microphone 102 </ b> B is attached to the lower end portion of the back surface of the duct member 101 at the center in the left-right direction. The second microphone 102 </ b> B is provided at a position facing the exhaust port 20, and faces the central portion of the exhaust port 20 in the left-right direction. The first microphone 102 </ b> A and the second microphone 102 </ b> B are arranged in the vertical direction at a predetermined interval, and the sound in the duct member 101 is input to each of them.

  Speakers 103 are attached to the upper portions of the left and right end surfaces of the duct member 101 from the outside at positions closer to the exhaust port 20 than the first microphone 102A in the vertical direction. On the other hand, the second microphone 102 </ b> B is provided at a position closer to the exhaust port 20 in the vertical direction than the speaker 103. That is, each speaker 103 is provided at a position that is different in the vertical direction with respect to each microphone 102A, 102B in the duct member 101, and the distance from the second microphone 102B is longer than the distance from the first microphone 102A. Is arranged. These two speakers 103 face each other in the left-right direction via a duct-like space 104 in the duct member 101, and are attached toward the other facing speaker 103.

  Drive sound generated from the cooling device 12 in the housing 2 and traveling backward in the duct-shaped space 22 enters the duct member 101 through the exhaust port 20, and passes through the duct-shaped space 104 in the duct member 101. Pass through the upper opening 101A. At this time, the drive sound that has entered the duct member 101 via the exhaust port 20 is input to the second microphone 102B near the exhaust port 20 and then input to the first microphone 102A in the vicinity of the opening 101A. In addition, sound from the two speakers 103 provided in the vicinity of the first microphone 102A is also input to the first microphone 102A through the duct-like space 104 in the duct member 101.

  In the vending machine 1 of the present embodiment, the sound output from the speaker 103 is controlled based on the input signal from the first microphone 102A or the second microphone 102B, and the drive sound generated in the housing 2 is supported. By outputting the sound to be output from the speaker 103, the drive sound generated in the housing 2 can be silenced by so-called active silencing.

  That is, if the output sound from the speaker 103 is controlled based on the input signal from the second microphone 102B closer to the cooling device 12 than the speaker 103, the drive sound can be silenced by feedforward control. On the other hand, if the output sound from the speaker 103 is controlled based on the input signal from the microphone 102B farther from the cooling device 12 than the speaker 103, the drive sound can be silenced by feedback control. When a stable driving sound with a peak below a predetermined threshold is generated, the driving sound is muted by feedback control. When a random driving sound with a peak exceeding the threshold is generated, feedforward control is performed. By silencing the drive sound, the drive sound can be effectively silenced.

  FIG. 5 is a schematic diagram for explaining the principle of active silencing performed in the vending machine 1. Driving sound generated from the compressor 16 and the blower 18 disposed in the duct-like space 22 in the housing 2 travels in the duct-like space 22 in the front-rear direction. The driving sound that travels backward in the duct-shaped space 22 enters the duct member 101 from the exhaust port 20 as indicated by an arrow in the figure, and passes through the duct-shaped space 104 in the duct member 101. In the process, the driving sound is sequentially input to the second microphone 102B and the first microphone 102A.

  The control unit 10 is provided with a phase adjustment amplification circuit 10A as sound signal generation means for generating a sound signal based on input signals from the microphones 102A and 102B. From the two speakers 103 provided in the silencer 100, sounds based on the sound signal generated by the phase adjustment amplifier circuit 10A are output at the same volume, and the sound output from the speakers 103 is a duct in the duct member 101. It goes to the opening 101A side through the space 104. The sound traveling from the speaker 103 toward the opening 101A is input to the first microphone 102A located closer to the opening 101A than the speaker 103.

  The phase adjustment amplifier circuit 10A performs feedback control or feedforward control by performing processing for shifting the phase of a signal of a specific frequency and processing for increasing the amplitude based on the signals input from the microphones 102A and 102B. Do. That is, in the case of feedback control, the input signal corresponding to the drive sound is extracted by removing the input signal corresponding to the output sound from the speaker 103 from the input signal from the first microphone 102A. Then, the sound from the speaker 103 input to the first microphone 102A has an opposite phase with respect to the input signal corresponding to the driving sound of the specific frequency extracted based on the input signal from the first microphone 102A. While the phase is adjusted, the amplitude is increased so that the sound from the speaker 103 input to the first microphone 102A has the same amplitude.

  On the other hand, in the case of feedforward control, the input signal corresponding to the drive sound is extracted by removing the input signal corresponding to the output sound from the speaker 103 from the input signal from the second microphone 102B. . Then, the sound from the speaker 103 input to the first microphone 102A has an opposite phase with respect to the input signal corresponding to the driving sound of the specific frequency extracted based on the input signal from the second microphone 102B. While the phase is adjusted, the amplitude is increased so that the sound from the speaker 103 input to the first microphone 102A has the same amplitude.

  Thus, in the feedback control, the phase and amplitude of the sound output from the speaker 103 is adjusted afterwards based on the input signal from the first microphone 102A, whereas in the feedforward control, the sound is output from the speaker 103. The phase and amplitude of the output sound are determined in advance based on the input signal from the second microphone 102B. In the case of feedforward control, it is possible to detect whether or not the drive sound can be silenced satisfactorily based on the input signal from the first microphone 102A.

Here, when sound is generated in the duct-shaped space 22 in the housing 2, a one-dimensional sound field is formed in the duct-shaped space 104 in the duct member 101 communicating with the duct-shaped space 22. In such a one-dimensional sound field, the sound wave propagating in the duct-like space 104 can be regarded as a plane wave when a condition such as the following formula (1) is satisfied. Can be silenced.
d << λ / 2 Formula (1)
d: inner diameter of duct λ: wavelength of sound

  Since the compressor 16 is driven by an AC motor, the driving sound of the compressor 16 peaks at different frequencies depending on the frequency of the supplied AC commercial power. More specifically, the driving sound of the compressor 16 has a peak at a frequency n times (n is a natural number) with respect to the frequency of the AC commercial power supply. Among the driving sounds generated from the compressor 16, the driving sounds tend to be particularly disturbing at the relatively low frequencies of n = 1 and n = 2. That is, the compressor 16 generates an unpleasant driving sound in the range of about 50 to 120 Hz.

  On the other hand, since the blower 18 is driven by a DC motor, a driving sound peak occurs at a specific frequency. Specifically, the driving sound of the blower 18 depends on the number of blades provided in the blower 18 and the number of rotations. In the present embodiment, a peak is generated at about 140 Hz. In this way, the drive sound from the blower 18 that has a peak at a relatively low frequency tends to be particularly disturbing compared to the drive sound from other components other than the compressor 16. Moreover, when the peak of the frequency of the drive sound each generate | occur | produced from the compressor 16 and the air blower 18 is adjoining like this Embodiment, there exists a tendency for a drive sound to be heard more harshly.

  As described above, the annoying driving sound generated from the compressor 16 and the blower 18 is distributed in a frequency band of about 50 to 140 Hz. The sound wavelength λ corresponding to such a frequency band is about 2.4 to 6.8 m. On the other hand, the inner diameter d of the duct-shaped space 104 is several centimeters to several tens of centimeters. These numerical values satisfy the condition of the above formula (1), and the sound waves from the compressor 16 and the blower 18 propagating in the duct-like space 104 can be regarded as plane waves. Thus, the drive sound from the compressor 16 and the blower 18 can be silenced satisfactorily.

  FIG. 6 is a waveform diagram for explaining a mode in which the driving sound is silenced by superimposing antiphase plane waves. FIG. 6A is a driving sound from the compressor 16 or the blower 18 input to the first microphone 102A. (B) shows the waveform of the sound from the speaker 103 inputted to the first microphone 102A, and (c) shows the waveform of the synthesized wave of these sounds. The drive sound generated from the compressor 16 or the blower 18 enters the duct member 101 through the exhaust port 20 and is input to the first microphone 102A with a waveform as shown in FIG.

  On the other hand, the sound output from the speaker 103 is subjected to feedback control based on the input signal from the first microphone 102A or feedforward control based on the input signal from the second microphone 102B. As shown in FIG. 6B, the phase is opposite to the driving sound of a specific frequency from the compressor 16 or the blower 18 when being input to the first microphone 102A. Therefore, the drive sound of the specific frequency from the compressor 16 or the blower 18 and the sound output from the speaker 103 are superimposed on each other when input to the first microphone 102A as shown in FIG. By canceling each other, the driving sound of the frequency is muted.

  In the present embodiment, the sound signal is such that the sound from the speaker 103 input to the first microphone 102A has an opposite phase to the driving sound generated by the vending machine 1 input to the first microphone 102A. By generating the sound, it is possible to cause the sound from the speaker 103 to interfere with the driving sound and to mute the driving sound. That is, the sound output from the speaker 103 has an opposite phase to the driving sound generated by the vending machine 1 at the position reaching the first microphone 102A, and the driving sound is muted by sound wave interference. This does not passively mute the driving sound generated by the vending machine 1 using a silencing member or the like, but actively generates a sound having a phase corresponding to the driving sound by feedback control or feedforward control. The drive sound can be muted. In this way, by adopting a configuration in which the driving sound is silenced using sound wave interference, unlike the configuration in which the silencing member is used, the driving sound generated by the vending machine 1 is effectively silenced. be able to. However, if a silencer member is provided in the duct member 101, it is possible to further improve the silencer effect.

  Normally, the vending machine 1 is installed with its back face facing a wall surface. At this time, a predetermined space is formed between the back face and the wall surface of the vending machine 1. In the present embodiment, the first microphone 102 </ b> A, the second microphone 102 </ b> B, and the speaker 103 are provided on the duct member 101 that extends in the vertical direction along the back surface of the vending machine 1, thereby forming the back surface side of the vending machine 1. In addition, by arranging each part in a space having a relatively small depth, it is possible to mute the driving sound that has entered the duct member 101 from the vending machine 1 through the exhaust port 20. Therefore, it is possible to mute the driving sound generated by the vending machine 1 by effectively using the space.

  In particular, when the duct member 101 is provided on the back surface of the target device that is long in the vertical direction as in the vending machine 1, the duct member 101 can be formed longer in the vertical direction. The distance between the second microphone 102B and the speaker 103 can be made longer. Thus, if the distance between the second microphone 102B and the speaker 103 is made longer, the drive sound muffling process by the feedforward control can be performed better.

Embodiment 2. FIG.
In the first embodiment, the duct member 101 of the silencer 100 has the configuration in which the back surface and the left and right end surfaces are provided, and the first microphone 102A and the second microphone 102B are provided on the back surface. On the other hand, in the second embodiment, the back surface of the duct member 201 is omitted, and the mounting positions of the first microphone 102A and the second microphone 102B are different from those in the first embodiment.

  FIG. 7 is a schematic sectional side view showing an example of the configuration of the vending machine 1 to which the silencer 200 according to the second embodiment of the present invention is applied. This embodiment has the same configuration as that of the first embodiment except that the back surface of the duct member 201 is omitted and the attachment positions of the first microphone 102A and the second microphone 102B are different. Therefore, the same reference numerals are assigned to the same components in the drawings, and the description is omitted.

  The duct member 201 of the silencer 200 of the present embodiment has left and right end surfaces and a lower surface that have the same configuration as the duct member 101 of the silencer 100 of Embodiment 1, but the back surface is open. That is, the duct member 201 of the present embodiment is configured by the back surface of the casing 2 of the vending machine 1 and the left and right end surfaces and the bottom surface that protrude rearward from the back surface.

  The first microphone 102A and the second microphone 102B provided on the back surface of the duct member 101 in the silencer 100 of the first embodiment constitute the front surface of the duct member 201 in the silencer 200 of the present embodiment. It is provided on the back surface of the housing 2. More specifically, the first microphone 102 </ b> A is provided above the speaker 103 and below the opening 101 </ b> A formed at the upper end of the duct member 201 on the back surface of the housing 2. On the other hand, the second microphone 102 </ b> B is provided below the speaker 103 and above the exhaust port 20 on the back surface of the housing 2.

  The first microphone 102 </ b> A and the second microphone 102 </ b> B are arranged above the central portion in the left-right direction of the exhaust port 20 with a predetermined interval in the vertical direction. In addition, since the 2nd microphone 102B can extend the distance with the speaker 103, the direction provided in the vicinity of the exhaust port 20 can perform feedforward control based on the input signal from the 2nd microphone 102B more favorably. be able to.

  In the present embodiment, as shown in FIG. 7, by installing the vending machine 1 so that the duct member 201 whose rear surface is opened contacts the wall surface W, the rear surface of the duct member 201 is configured by the wall surface W. Therefore, the manufacturing cost can be further reduced.

Embodiment 3 FIG.
In the first embodiment, the configuration in which the first microphone 102A and the second microphone 102B are provided in the duct member 101 of the silencer 100 has been described. On the other hand, in the third embodiment, the second microphone 102B is omitted, and only the first microphone 102A is provided in the duct member 301.

  FIG. 8 is a schematic cross-sectional side view showing a configuration example of the vending machine 1 to which the silencer 300 according to the third embodiment of the present invention is applied. In the present embodiment, except that the length of the duct member 301 is different in the vertical direction and the second microphone 102B is omitted and the mounting positions of the first microphone 102A and the speaker 103 are different. Since the configuration is the same as that of the first embodiment, the same reference numerals are given to the same configuration, and the description is omitted.

  The duct member 301 of the silencer 300 of the present embodiment has a back surface, left and right end surfaces, and a bottom surface, similar to the duct member 101 of the silencer device 100 of Embodiment 1, but the upper ends of the back surface and the left and right end surfaces are implemented. The duct-shaped space 104 in the duct member 301 is shortened by being formed lower than the case of the first form. The first microphone 102 </ b> A is attached to the central portion in the left-right direction of the upper end portion on the back surface of the duct member 301. Speakers 103 are attached to the left and right end surfaces of the duct member 301 from the outside at positions below the first microphone 102A and above the exhaust port 20, respectively.

  When such a duct-like space 104 has a short configuration, it is difficult to satisfactorily perform feedforward control based on an input signal from the second microphone 102B as in the first embodiment, but from the speaker 103 Also, it is possible to mute the drive sound by performing feedback control in the same manner as in the first embodiment based on the input signal from the first microphone 102A provided above.

  In this example, the configuration in which the first microphone 102A is provided on the back surface of the duct member 301 has been described. However, as in the second embodiment, the back surface of the duct member 301 is omitted and the first microphone 102A is replaced by a vending machine. The structure provided in the back surface of the one housing | casing 2 may be sufficient. According to such a configuration, as in the case of the second embodiment, the vending machine 1 is installed so that the duct member 301 whose back surface is opened contacts the wall surface. Since the back surface can be configured, the manufacturing cost can be further reduced.

  In the above embodiment, the configuration has been described in which the duct members 101, 201, 301 communicate with the exhaust port 20 at the lower ends thereof and extend upward from the exhaust port 20. However, the present invention is not limited to such a configuration, and the duct member communicates with an opening other than the exhaust port 20 formed on the back surface of the casing 2 so as to mute the driving sound entering the duct member from the opening. It may be a simple configuration. Further, the duct member may be configured to communicate with an opening formed on the back surface of the housing 2 at the upper end portion thereof and to extend downward from the opening portion.

  Moreover, although the above embodiment demonstrated the case where a sound signal production | generation means was comprised by the control unit 10 with which the vending machine 1 was equipped, not only such a structure but a sound signal production | generation means is comprised. By providing the control device on the duct member, the silencer may be configured as an integral silencer unit.

  Furthermore, although the case where the silencer 100, 200, 300 is applied to the vending machine 1 has been described in the above embodiment, the present invention is not limited to such a configuration. It can be applied to various target devices such as air conditioners and blowers.

It is the figure which showed one structural example of the vending machine to which the silencer by Embodiment 1 of this invention was applied, (a) is a front view, (b) has shown the side view. It is the front view which showed the state which opened the opening / closing door of the vending machine of FIG. It is a schematic sectional side view of the vending machine of FIG. It is the perspective view which looked at the vending machine of FIG. 1 from the back side. It is a schematic diagram for demonstrating the principle of the active muffling performed in this vending machine. It is a wave form diagram for explaining a mode which silences a drive sound by superposition of an antiphase plane wave, (a) is a waveform of a drive sound from a compressor or a fan inputted into the 1st microphone, and (b) is. The waveform of the sound from the speaker input to the first microphone, (c) shows the waveform of the synthesized wave of these sounds. It is the schematic sectional side view which showed the example of 1 structure of the vending machine to which the silencer by Embodiment 2 of this invention was applied. It is the schematic sectional side view which showed the example of 1 structure of the vending machine to which the silencer by Embodiment 3 of this invention was applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vending machine 2 Case 10 Control unit 10A Phase adjustment amplification circuit 20 Exhaust port 22 Duct-like space 100,200,300 Silencer 101,201,301 Duct member 101A Opening part 102A First microphone 102B Second microphone 103 Speaker 104 Duct space

Claims (4)

A duct member provided so as to extend in the vertical direction along the back surface of the target device, and communicated with the opening formed in the back surface at one end portion in the vertical direction;
A first microphone provided in the duct member, to which a driving sound that has entered the duct member from the target device through the opening is input;
Sound signal generating means for generating a sound signal;
A speaker that is provided in a position closer to the opening than the first microphone in the duct member in the vertical direction, and that outputs a sound based on the sound signal generated by the sound signal generating means;
The sound signal generating means generates a sound signal so that a sound from the speaker input to the first microphone has a phase opposite to that of the driving sound input to the first microphone. A silencer.   The muffler according to claim 1, wherein the sound signal generation means generates a sound signal based on an input signal from the first microphone. A second microphone provided at a position closer to the opening than the speaker in the duct member in a vertical direction, to which driving sound that has entered the duct member from the target device through the opening is input; Prepared,
2. The silencer according to claim 1, wherein the sound signal generating means generates a sound signal based on an input signal from the second microphone.   The silencer according to claim 1, wherein a rear surface of the duct member is opened.

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