JP3897466B2 - Active silencer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an active silencer disposed in an exhaust gas path provided with a heat engine such as a gas engine or a gas turbine on the upstream side for the purpose of silencing.
[0002]
[Prior art]
As a conventional example of the above active silencer, for example, there is one disclosed in Japanese Patent Publication No. 8-23755. As disclosed in this publication, the active silencer includes an acoustic device acoustically connected to a sound wave propagation path via a connection path. Such an acoustic device is provided on the upstream side of the propagation path and is provided on the downstream side of the first sensor microphone for extracting information on the propagation sound wave from the noise source, and performs interference mute on the propagation sound wave. A speaker that artificially generates additional sound waves, a second sensor microphone that is provided on the downstream side of the speaker and evaluates the silencing effect, and the like.
[0003]
Conventionally, such an acoustic device is directly connected to a sound wave propagation path (for example, an exhaust gas path) through a connection path, and such an acoustic device is installed in an exhaust gas path of, for example, a gas engine or a gas turbine. In some cases, the exhaust gas pipe is exposed to a relatively high temperature and high humidity exhaust gas flowing in the exhaust gas pipe.
[0004]
[Problems to be solved by the invention]
High-temperature and high-humidity exhaust gas may condense due to a temperature difference between the connection path and the inside of the exhaust pipe. When such condensation occurs, the sensor microphone, the speaker, and the like are electronic devices, and thus reliability and durability are significantly reduced when water droplets adhere (see, for example, Japanese Patent Laid-Open No. 6-129227).
[0005]
Accordingly, an object of the present invention is to provide an active silencer in which the reliability and durability of an acoustic device such as a speaker installed in a place where condensation is likely to occur as described above is improved.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an acoustic device acoustically connected to a sound wave propagation path connected to a noise source on the upstream side via a connection path. In the active silencer provided, the connection path is connected vertically and obliquely downward to the sound wave propagation path, and the connection path includes a shut-off damper for shutting off the acoustic device from the exhaust gas flowing through the sound wave propagation path. The acoustic device can be cut off from the exhaust gas flowing through the sound wave propagation path .
[0007]
According to the above configuration, the cooling air from the cooling fan is introduced into the connection path, and the installation location of the acoustic device exposed to the high-temperature and high-humidity exhaust gas is cooled and dehumidified.
Therefore, it becomes possible to easily maintain the temperature and humidity of the audio equipment installed in a place where condensation is likely to occur, in accordance with the specifications of the equipment. As described above, according to the present invention, the ambient environment of the acoustic device of the active silencer can be made suitable for each device only by the structural change of connecting the cooling fan to the acoustic device installation location.
Further, water droplets condensed on the connection path are prevented from falling by their own weight along the inclined surface of the connection path from the acoustic device installation location toward the sound wave propagation path and adhering to the acoustic device such as a speaker.
Therefore, even if an acoustic device is installed at a place where condensation is likely to occur only by a structural change of devising the connection posture (angle) of the connection pipe with respect to the sound wave propagation path, the acoustic device can be removed from such a disadvantageous environment. Can be protected.
Furthermore, by providing a cutoff damper in the connection path, it is possible to quickly protect the acoustic device when an abnormality occurs in the surrounding environment of the acoustic device.
In addition, since a special specification change is not required for a device such as a speaker itself, the active silencer according to the present invention greatly expands the allowable range with respect to the specification of the acoustic device. On the other hand, the device was able to maintain the reliability of the device in its operation and improve the durability.
[0008]
In order to achieve the above object, in addition to the configuration according to claim 1, as described in claim 2, the opening state of the shut-off damper is temperature information from a sensor installed in the cooling fan. Or it is controlled based on the temperature information or humidity information from the sensor installed in front of the said audio equipment.
[0009]
According to the above configuration, when the detected temperature becomes higher than the predetermined value due to a failure of the cooling fan, or when the detected humidity becomes higher than the predetermined value due to condensation near the acoustic device, the cutoff damper can Equipment can be protected quickly.
[0010]
In addition to the configuration described in claim 1 or 2 , the suction port of the cooling fan is installed vertically downward, and a conical cover is installed around the suction port. When a dustproof filter is installed, it is further advantageous in the following points.
[0011]
The inlet of the cooling fan for introducing outside air into the connection path is exposed outdoors. Therefore, the cooling fan is easily damaged by rainwater. In addition, dust from the engine, turbine, etc. easily enters the active silencer through the inlet of the cooling fan. Nevertheless, no conventional active silencer has been considered for waterproofing measures and dustproofing measures when the air cooling device is connected to the active silencer outdoors.
However, in the present invention, since the suction port of the cooling fan is installed vertically downward and a conical cover is installed around the suction port, it is possible that rainwater or the like is applied to the cooling fan. It is also possible to effectively prevent the water from passing through the connection path. In addition, since a dustproof filter is installed at the suction port of the cooling fan, it is possible to prevent a dust from entering the inside through the cooling fan.
[0012]
In this way, by taking all possible measures for waterproofing and dustproofing cooling fans, the durability of the cooling fans is improved and the reliability and durability of the audio equipment installed in the connection path is also improved. The reliability and durability of the entire active silencer are also improved.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of an active silencer according to the present invention will be described with reference to the drawings.
FIG. 1 schematically shows the overall structure of the active silencer 1. The exhaust gas from the gas engine 2 (corresponding to the noise source) passes through the exhaust pipe (corresponding to the sound wave propagation path) 4 in the direction indicated by the arrow 3, and at this time, the sound wave transmitted from the engine 2 is also transmitted as noise.
[0014]
A duct (an example of a connection path) 5 branches from the exhaust pipe 4, and the acoustic device of the active silencer 1 is installed in the duct 5. The acoustic device is provided on the upstream side of the speaker 13 in the exhaust pipe 4 as a sound wave propagation path from the gas engine 2 to detect information on the propagated sound wave, for example, characteristics such as phase and sound pressure (amplitude). The first sensor microphone 11, the control device 12 that processes the detection information and creates information (electrical signal or the like) indicating the additional sound wave having the same phase and the same sound pressure as the propagation sound wave, radiates the additional sound wave and transmits the propagation sound wave From the speaker 13, which is provided on the downstream side of the speaker 13, and the second sensor microphone 14 which detects information for evaluating the effect of the interference mute, the cooling fan 15 which cools the speaker 13 with the outside air, and the like It is configured.
[0015]
FIG. 5 is a side view of the duct 5 shown in FIG. As shown in FIG. 5, the duct 5 is vertically obliquely downward with respect to the exhaust pipe 4 that is a sound wave propagation path (that is, on the exhaust pipe 4 side at an angle larger than 0 ° in both the vertical direction and the horizontal direction). Connected). When the duct 5 is arranged vertically obliquely downward with respect to the exhaust pipe 4 in this way, water droplets condensed inside the duct 5 as a connection path hang down toward the exhaust pipe 4 as a sound wave propagation path. For this reason, the water droplets of dew condensation do not adhere to the speaker 13, the function deterioration of the speaker 13 is prevented, and the durability of the speaker 13 improves. Note that the speaker 13 is also connected to the exhaust pipe 4 in an obliquely downward direction, similarly to the duct 5.
[0016]
Although not shown, the duct 5 a between the first sensor microphone 11 and the exhaust pipe 4 and the duct 5 b between the second sensor microphone 14 and the exhaust pipe 4 are also perpendicular to the exhaust pipe 4. Connected diagonally downward.
[0017]
The first sensor microphone 11 is composed of a pair of a normal use microphone 11a and a backup microphone 11b. In normal times, the microphone 11a is used and connected to the control device 12 via the automatic changeover switch 23. However, when a failure or the like occurs, the failure detection panel 9 detects the failure, and the automatic changeover switch 23 is turned on. And automatically switch to the backup microphone 11b.
The second sensor microphone 14 is also composed of a pair of a normal use microphone 14a and a backup microphone 14b. In normal times, the microphone 14a is used and connected to the control device 12 via the automatic changeover switch 24. However, when a failure or the like occurs, the failure detection panel 9 detects the failure, and the automatic changeover switch 24 is turned on. And automatically switch to the backup microphone 14b.
[0018]
In the present invention, as shown in FIG. 2, a shut-off damper (blocker) for shutting off the speaker 13 from the exhaust gas flowing in the exhaust pipe 4 is connected to the duct 5 as a connection path between the active silencer 1 and the exhaust pipe 4. Example 6) is installed. The shut-off damper 6 is configured to be openable and closable both automatically and manually.
The shut-off damper 6 rotates around the vertical axis 10 and the first state (broken line) in which the gas flowing through the sound wave propagation path circulates between the sound wave propagation path and the speaker 13 arrangement portion, and the first state that blocks the flow. It is configured to be switchable between two states (solid line). Hereinafter, the operation of the cutoff damper 6 will be described with reference to FIGS. 3 and 4.
[0019]
FIG. 3 is a flowchart for explaining the operation of the cutoff damper 6 when an abnormality occurs in the cooling fan 15.
When an abnormality occurs in the cooling fan 15, the shut-off damper 6 is automatically operated to the second state, and the duct 5 is shut off from the exhaust gas flowing through the exhaust pipe 3. Here, regarding abnormality detection, the first abnormality detection sensor 7 installed in the cooling fan 15 for cooling the speaker 13 detects abnormality (step # 10). In order to determine an abnormal situation, the cooling fan 15 is not operated normally, and therefore the detection temperature of the first abnormality detection sensor (an example of an abnormality detection means) 7 is higher than a predetermined value. Is possible. In this case, the first abnormality detection sensor 7 is configured as a temperature sensor.
[0020]
The abnormal situation is transmitted to the failure detection panel 9 connected to the first abnormality detection sensor 7. Then, the failure detection panel 9 functions as a breaker operation control mechanism, and gives an opening command signal to the shut-off damper 6 to automatically shut off the shut-off damper 6 (when the shut-off is performed, the opening degree 0 ° is represented. Signal). The abnormal situation is transmitted from the failure detection panel 9 to notifying means (not shown) such as an alarm lamp and an alarm buzzer, and the monitor can recognize the occurrence of the abnormal situation. In response to the opening command signal, the cutoff damper 6 is switched from the first state at the time of normal opening to the second state at the time of abnormal cutoff (step # 20). Thereby, the active silencer 1 is cut off from the exhaust gas flowing through the exhaust pipe 4, and the acoustic equipment of the active silencer 1 is quickly protected. By shutting off the shut-off damper 6, the cooling fan 15 can be repaired without being bothered by high-temperature (about 300 ° C.) exhaust gas from the exhaust pipe 4 and without stopping the operation of the gas engine 2. It becomes possible (step # 30). When the repair work is completed, the cutoff damper 6 is manually restored to the open state, that is, the first state (step # 40).
[0021]
A second abnormality detection sensor 8 is installed in front of the speaker 13. Similar to the first abnormality detection sensor 7, the second abnormality detection sensor 8 is also connected to the failure detection panel 9. If the detected temperature becomes higher than a predetermined value due to a failure of the cooling fan 15 or the detected humidity becomes higher than a predetermined value due to condensation near the speaker 13, this is notified to the failure detection panel 9. Then, the same treatment as when an abnormality is detected by the first abnormality detection sensor 7 is performed. That is, the second abnormality detection sensor 8 is a temperature sensor or a humidity sensor.
[0022]
FIG. 4 is a flow for explaining the operation of the cutoff damper 6 when maintaining the speaker 13 which is an acoustic device. When the speaker 13 is maintained, the operator manually closes the shut-off damper 6 to switch to the second state (step # 110) and performs necessary maintenance work (step # 120). When the work is completed, the cutoff damper 6 is manually restored to the open state, that is, the first state (step # 130).
[0023]
As shown in FIG. 1, third and fourth abnormality detection sensors (temperature sensors or humidity sensors) 21 and 22 are also installed at the front portions of the first sensor microphone 11 and the second sensor microphone 14. . The duct 5a, which is a connection path between the first sensor microphone 11 and the exhaust pipe 4, and the duct 5b, which is a connection path between the second sensor microphone 14 and the exhaust pipe 4, are provided with a cutoff damper 6 as a cutoff tool. Similar cutoff dampers 6 a and 6 b are installed in a connected state with the failure detection panel 9.
[0024]
The cooling fan 15 is connected to the duct 5 through the discharge port 16, and an outside air duct 17 is extended outside in order to introduce outside air into the duct 5. A suction port 18 of the cooling fan 15 is provided at the end of the outside air duct 17 opposite to the discharge port 16 so as to be exposed outdoors.
[0025]
As shown in FIGS. 6 and 7, the suction port 18 is installed vertically downward. The suction port 18 is configured by connecting a main body portion 18a made of a pipe made of polyvinyl chloride or the like to the exposed side end portion of the outside air duct 17, and surrounding the outer periphery of the main body portion 18a with an umbrella-shaped or conical cover 18b. . The cover 18b prevents rainwater or the like from entering the cooling fan 15 or from entering the duct 5 through the cooling fan 15. Further, a dust-proof filter 18c is hung on the tip of the main body 18a of the suction port 18 to prevent foreign matter from entering from the suction port 18. The filter 18c is formed of a fine mesh, but can be made of other suitable materials.
[0026]
[Another embodiment]
FIGS. 8A to 8G show various alternative embodiments of the cooling fan 15 suitable for use in the active silencer according to the present invention. Various configurations can be adopted for the structure of the cooling fan 15, the connection location and connection method to the duct 5, and the positional relationship with respect to the speaker 13 as shown in the drawings.
[0027]
In FIG. 8A, the cooling fan 15 is provided behind the speaker 13, and the cooling air passes from the back of the speaker 13 to the front through the outer periphery. As disclosed in Japanese Patent Laid-Open No. 6-129227, waterproofing of the rear surface side of the speaker is not easy, but with this configuration, the waterproof effect on the rear surface side can be enhanced.
[0028]
In FIG. 8 (b), the discharge port 16 of the cooling fan 15 is installed facing the speaker 13. By disposing the cooling fan 15 facing the speaker 13, it is easy to prevent condensation at the front portion of the speaker 13.
[0029]
In FIG. 8 (c), a plurality of discharge ports 16 of the cooling fan 15 are provided along the inner peripheral surface of the duct 5 at intervals in the circumferential direction. In the case of this structure, there is an effect that the cooling air can be dispersed and the cooling effect can be made uniform.
[0030]
In FIG. 8D, the discharge port 16 of the cooling fan 15 is arranged toward the exhaust pipe 4. In the case of this structure, there is an effect that introduction of high-temperature and high-humidity exhaust gas from the exhaust pipe 4 into the duct 5 is suppressed by the cooling air from the discharge port 16.
[0031]
In FIG. 8 (e), the discharge port 16 of the cooling fan 15 is arranged toward the exhaust pipe 4 as in the example of FIG. 8 (d). Furthermore, in this example, a plurality of discharge ports 16 are provided in the vertical direction. In the case of this structure, in addition to the effect obtained from the structure shown in FIG. 8 (d), there is an effect that the cooling effect can be made uniform.
[0032]
In FIG. 8F, the cooling fan 15 is installed at a position closer to the exhaust pipe 4 than in the above-described embodiment. By disposing the cooling fan 15 close to the exhaust pipe 4, there is an effect that introduction of high-temperature and high-humidity exhaust gas from the exhaust pipe 4 into the duct 5 is suppressed.
[0033]
In FIG. 8G, the outside air duct 17 bypasses the periphery of the duct 5 and then is introduced into the duct 5. In the case of this structure, by providing means (not shown) for cooling the outside air in the middle of detouring, cooling air having a temperature lower than that of the outside air is introduced into the duct 5 to further enhance the cooling effect. Is possible.
[0034]
Each of the above-described embodiments can also be applied between the sensor microphones 11 and 14 and the cooling fan 15.
[0035]
In addition, since water droplets do not escape, the effect as in the case of inclining the duct 5 cannot be expected. However, the duct 5 is provided horizontally as in the past, and only the acoustic device such as the speaker 13 is inclined vertically and downward with respect to the exhaust pipe 4. However, it is possible to prevent water droplets from adhering to the acoustic device.
[0036]
Furthermore, in the present invention, the cross-sectional shape of the exhaust pipe 4 can be an arbitrary shape such as a circle or an ellipse in addition to a rectangular shape as shown in FIG.
[0037]
【The invention's effect】
As described above, in the active silencer 1 according to the present invention, the acoustic device is cooled with respect to the duct 5 that is a connection path between the exhaust pipe 4 that is a sound wave propagation path and the acoustic device such as the speaker 13. By simply changing the structure of connecting the cooling fan 15, it is possible to obtain equipment specifications suitable for the acoustic equipment of the active silencer 1 with respect to temperature and humidity. Moreover, no special specification change is required for the devices such as speakers. Therefore, it is possible to cover a wide range of specifications of the audio equipment, maintain the reliability of the equipment, and improve the durability.
[0038]
Further, only by devising the connection angle of the duct 5 that is the connection path to the exhaust pipe 4, even if the acoustic device is installed at a place where condensation easily occurs, the acoustic device is protected from such an adverse environment. be able to. Therefore, the reliability of the device can be maintained and the durability can be improved.
[Brief description of the drawings]
FIG. 1 is a plan view schematically showing an active silencer. FIG. 2 is an enlarged view of a main part of FIG. 1. FIG. 3 is a flowchart explaining the operation of a circuit breaker when a cooling fan is abnormal. Flow diagram explaining the operation of the tool [Fig. 5] Side view of the duct [Fig. 6] Overview of the cooling fan inlet [Fig. 7] Exploded view of the cooling fan inlet [Fig. 8] The figure which shows another embodiment of a cooling fan
DESCRIPTION OF SYMBOLS 1 Active silencer 2 Noise source 5,5a, 5b Connection path 11,13,14 Acoustic equipment 15 Cooling fan

Claims (2)

In an active silencer comprising an acoustic device acoustically connected via a connection path to a sound wave propagation path connected to a noise source on the upstream side,
A cooling fan for cooling the acoustic device is connected to the connection path,
The connection path is connected vertically and obliquely downward to the sound wave propagation path;
An active silencer characterized in that the connection path is provided with a shut-off damper for shutting off the acoustic device from the exhaust gas flowing through the sound wave propagation path, and the sound device can be shut off from the exhaust gas flowing through the sound wave propagation path by the shut-off damper. . The opening state of the cutoff damper is controlled based on temperature information from a sensor installed in the cooling fan or temperature information or humidity information from a sensor installed in front of the acoustic device. The active silencer as described.

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