JP2001221026A - Active silencer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problem that there is a risk of breaking of a silencing signal output means by being exposed to a high temperature caused by a cooling fan incapable of being driven due to a voltage drop in engine starting when a conventional active silencer is disposed in an engine exhaust pipe. SOLUTION: In this active silencer, an exhaust duct 1 of an engine of an engine generator 2 is provided with a first noise detecting means 4, a speaker 3 disposed on the downstream of the duct to output a silencing signal, a cooling fan 7 for cooling the speaker 3, a controller 5 for controlling them, and a second noise detecting means 6 disposed in the downstream from the speaker. In the active silencer, an electric apparatus and a power input of an active silencer 10 are connected to the power supply output of the generator 2b through a main switch 54, a power input of the cooling fan 7 is connected to the preceding stage of the main switch 54 through a power supply switching circuit 50, and the generator and a power supply 14 for emergency are connected in parallel with the cooling fan through the power supply switching circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active silencer, in which an output means for outputting a silencing signal having a phase opposite to that of a noise signal is cooled so as not to be damaged by heat from an exhaust pipe of an engine. And a power supply circuit for driving the power supply.

[0002]

2. Description of the Related Art Conventionally, active muffling has been provided in which a speaker is provided in a duct such as an engine exhaust pipe, an air supply duct, and a ventilation duct, and a signal having a phase opposite to that of the noise in the duct is output from the speaker. The device is known. When such an active noise reduction device is disposed in an exhaust portion such as an muffler of an engine, a means for outputting a noise reduction signal such as a speaker is disposed at an end of a branch pipe branched from a noise passage duct.

[0003]

However, since the high-temperature exhaust gas from the engine passes through the duct through which the noise passes, the high-temperature heat may enter through the branch pipe and damage the output means. Therefore, in order to prevent the output means from being destroyed by heat, a fan is provided to cool the output means with its cooling air.However, in the case of an engine generator, the cooling fan is driven by electric power from the generator. Since the specified voltage was not reached and stabilized for a few minutes after the engine was started, the cooling fan did not operate without power being supplied, and the mute output means was damaged by heat at startup. was there. In addition, if the generator or the engine fails, the cooling fan also stops, and the hot air from the exhaust pipe exposes the output unit to a high temperature even for a short time, and may be damaged. Therefore, the present invention connects a drive power supply circuit for the cooling fan to the preceding stage of the main power switch to supply power to the cooling fan and drive it almost simultaneously with starting the engine, cool the output means, and It is connected in parallel with the emergency power supply to cool the output means when a failure or the like occurs or until the output power of the generator is started.

[0004]

The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described. That is, in the first aspect, the first noise detecting means is provided in the exhaust duct of the engine of the engine generator, the means arranged downstream of the duct to output a muffling signal, and the muffling signal output means is cooled. Means, a calculating means for calculating a silence signal of an opposite phase to the noise signal detected by the first noise detecting means, and a second noise detecting means arranged downstream from the output means. In the active silencer having, the power output of the generator is connected to the power supply of the electric equipment and the active silencer via a main switch, and the power supply of the cooling means is connected to the power of the main switch via a power supply switching circuit. Connected to the previous stage.

According to a second aspect of the present invention, first noise detecting means is provided in an exhaust duct of an engine of an engine generator, means arranged downstream of the duct to output a muffling signal, and said muffling signal output means is provided. Means for cooling, a calculating means for calculating a silencing signal having an opposite phase to the noise signal detected by the first noise detecting means, and a second noise arranged downstream from the output means. In an active silencer having a detecting means, an output power supply of the generator and an emergency power supply juxtaposed to an engine generator are connected in parallel to the cooling means via a power supply switching circuit, and when an engine generator fails, The power supply switching circuit is switched to supply power from the emergency power supply to drive the cooling means.

According to a third aspect of the present invention, first noise detecting means is provided in an exhaust duct of an engine of an engine generator, means arranged downstream of the duct to output a muffling signal, and said muffling signal output means is provided. Means for cooling, a calculating means for calculating a silencing signal having an opposite phase to the noise signal detected by the first noise detecting means, and a second noise arranged downstream from the output means. In the active silencer having a detecting means, an output power source of the generator and an emergency power source juxtaposed to an engine generator are connected to the cooling means via a power source switching circuit, and the power generator Alternatively, the power supply switching circuit is switched until the output power supply of another generator rises, and the cooling means is driven by the power from the emergency power supply.

[0007]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration and control of the active silencer of the present invention, FIG. 2 is a diagram showing a power supply switching circuit, and FIG. 3 is a block diagram for driving a cooling means from an emergency power supply when the engine generator is started. .

First, an outline of the active silencer will be described with reference to an example of an active silencer 10 configured to muffle exhaust noise of an engine generator. FIG. 1 shows a schematic configuration of the active silencer. A sound source passage duct 1 is connected to an exhaust pipe of an engine 2a of an engine generator 2 serving as a noise source (primary sound source) to form a one-dimensional sound field so that noise flows from left to right in FIG. On the noise source side of the sound source passage duct 1, that is, on the engine side (left side in FIG. 1), a first sound wave sensor 4 composed of a microphone is provided as first noise detection means. On the downstream side of the sensor 4 (on the right side in FIG. 1), a second sound sensor 6 composed of a microphone is provided as second noise detecting means.

The first sound wave sensor 4 of the sound source passage duct 1
A branch pipe 1a is arranged between the second sound wave sensor 6 and
A branch port 1b is opened in the branch pipe 1a, and a branch pipe 9 is communicated with an end of the branch port 1b. A speaker 3 as a sound output means and a cooling as a cooling means are connected to the end of the branch pipe 9. A fan 7 is arranged, a temperature sensor 13 is arranged near the speaker 3, and the temperature of the speaker 3 is detected. The cooling fan 7 cools the speaker 3 so as not to be damaged by heat transmitted from the sound source passage duct 1.

The branch pipe 1a and the first sound wave sensor 4
A passive silencer 11 composed of a plurality of sound arresters is arranged between the two, and in this embodiment, two passive shunts 11a and 11b are arranged in series to form the passive silencer 11. The passive silencer 11 silences and reduces high frequency noise. However, in the present embodiment, the passive silencer 11 is arranged upstream of the sound source passage duct 1, but may be arranged in the middle or downstream of the sound source passage duct 1.

The passive silencer 11 is formed, for example, in a substantially cylindrical shape, and has a sound absorbing member provided on an inner peripheral portion thereof. The sound absorbing member silences noise passing through the passive silencer. Have been. The internal volume of the passive silencer 11 provided with a sound absorbing member therein is set such that the effect of silencing high frequency noise is enhanced. The first sound sensor 4, the second sound sensor 6, the cooling fan 7, and the temperature sensor 13 are connected to the controller 5, and the speaker 3 is connected to the controller 5 via the amplifier 12. The first sound sensor 4 detects the exhaust sound which is noise, the speaker 3 outputs a sound wave having the opposite phase to the exhaust sound to mute the sound, and the second sound sensor 6 detects the result of the muffling action. Monitor and feed back to controller 5. The controller 5 calculates and calculates a muffling signal of the opposite phase to the noise signal detected by the first sound wave sensor 4 and controls the active muffling device 10 so as to calculate and output a more efficient muffling signal from the feedback signal. And also controls the engine generator 2, the alarm device 16, and the like.

The operation of the active silencer configured as described above will be described. That is, when the engine generator 2 is operated, when the engine is operated and the exhaust gas is exhausted from the sound source passage duct 1, the accompanying exhaust sound is detected by the first sound wave sensor 4, and the detection signal is transmitted to the controller 5. When the detection signal is input, the controller 5 generates a silence signal having the same amplitude and opposite phase. This silence signal is output to the speaker 3 via the amplifier 12, and
A sound-absorbing sound wave is output. Since the noise-reducing sound wave is made to have the same amplitude in the opposite phase to the exhaust sound emitted from the sound source passage duct 1, the exhaust sound is canceled by the noise-reducing sound wave, and the sound-muffling action is performed. . Further, a synthetic sound wave of the exhaust sound and the sound wave for silencing is detected (monitored) by the second sound wave sensor 6, and the result of the silencing operation is fed back to the controller 5, and the silencing signal is corrected so that the silencing operation is performed more sufficiently. Because

Generally, most of the exhaust noise components are relatively low frequency components composed of components determined by the rotational speed of the engine and the number of cylinders, and harmonics thereof. Upon detection, the lower the frequency component, the greater the degree of enhancement. For this reason, the first sound wave sensor 4
If the output signal is input to the controller 5 as it is, the noise canceling effect on the low frequency components increases, but the noise canceling effect on the components in the frequency region where the sensitivity is high and the noise tends to be harsh is insufficient.

Therefore, a passive silencer 11 is further provided in the active silencer 10 to provide a passive silencer having a high silencing effect in a high frequency range in addition to the silencing effect of the active silencer having a high silencing effect in a low frequency range. 11
Thus, the silencing effect is improved in all frequency ranges.

A lamp 17, a buzzer 19, a monitor 20, and the like are connected as an alarm device 16 to the controller 5, and the engine 2 a, the generator 2 b, the first sound sensor 4, the second sound sensor 6, and the cooling fan 7 are connected. And amplifier 1
2 or an emergency power supply 14 or an inverter 15 described later breaks down, an abnormal phenomenon occurs, or when the value detected by the temperature sensor 13 exceeds a set temperature, an alarm is issued and the monitor 20 displays the alarm. Devices, fault locations, data, etc. are displayed.

Next, the configuration of the drive power supply circuit of the cooling means for cooling the speaker 3 serving as the muffling output means of the present invention will be described. In FIG. 2, the generator 2b of the engine generator 2
Is an AC power supply, and the output of the generator 2b is supplied through an electric device (not shown) used in a factory, a building, a ship, or the like, a power supply for controlling an engine (not shown), or a power supply switching circuit 50. Connected to an active silencer 10 such as a controller 5, an amplifier 12, and a cooling fan 7. Further, a rotation speed sensor 51 provided on the engine 2a is connected to the controller 5, and detects the rotation speed of the engine 2a.

In the vicinity of the engine generator 2 or the active silencer 10, a battery is provided in parallel as an emergency power supply 14, and the emergency power supply 14
b, and the emergency power supply 14 is connected to an inverter 15 for converting to an alternating current because it is a direct current. The inverter 15 is connected to the controller 5 so as to operate in an emergency such as a failure of the engine generator 2 or a lightning strike.

In such a configuration, when the engine 2a is started and the voltage exceeds the set voltage, the main switch 54 is closed and the electric power generated by the generator 2b is input to the power supply switching circuit 50 with respect to the transformer 53. Power is supplied to the cooling fan 7 and the cooling fan 7 is driven. Then, when power is not supplied from the generator 2b due to a power failure or lightning strike due to a failure of the engine 2a or the generator 2b, the controller 5 detects this and activates an alarm device 16 to issue an alarm, and the inverter 15 Activated to switch the power supply switching circuit 50,
The power from the emergency power supply 14 is DC-AC converted, and the cooling fan 7 is driven via the power supply switching circuit 50.

Even if the engine generator 2 breaks down and the supply of AC power is stopped, power is supplied from the emergency power supply 14 to the cooling fan 7 so that the cooling fan 7 is driven without stopping and the sound source passage duct This prevents the loudspeaker 3 from being damaged due to hot air flowing into the branch pipe 9 from 1.
Then, after a predetermined time has elapsed by the timer 18 connected to the controller 5, or when the value from the temperature sensor 13 becomes equal to or lower than the set temperature, the inverter 15 is stopped to stop driving the cooling fan 7. .

The power supply switching circuit 50 includes a power generator 2
b from the output terminals 52a, 52b and 52c of the main switch 54.
The voltage is lowered (to 100 V) by the transformer 53 via the relay 55 and connected to the active silencer 10 such as the amplifier 12 and the cooling fan 7 via the contacts 55a and 55b of the relay 55. The main switch 54 is a relay (electromagnetic switch)
It is configured to be activated and closed by a command from a control circuit (not shown) when the voltage exceeds the set voltage, and to open when the current exceeds the set current. Alternatively, it is determined that the main switch 54 is connected to the controller 5 and when the value from the rotation speed sensor 51 becomes equal to or higher than the set rotation, the engine 2 reaches the operating rotation range and rises to the set voltage to obtain a stable voltage. Then, the main switch 54 may be operated.

When the voltage of the generator 2b is lower than the set voltage, the main switch 54 is opened, the relay 55 is not operated, and the contacts 55a and 55b are kept open, so that the cooling fan 7 is not driven. There is a possibility that the speaker 3 may be damaged by the hot air entering from the branch pipe 9. Therefore, the present invention provides a power supply output terminal 52 (52a.
52b or 52c), is connected to the cooling fan 7 via the auxiliary switch 62, the transformer 56, the contact 57a of the relay 57, and the contact 59a of the relay 59, and immediately after the start of the generator 2b. Power is supplied to drive the cooling fan 7. That is, the power is supplied from a stage preceding the main switch 54 in parallel with the power supplied from the main switch 54. The relay 57 is set to operate at a low voltage, and the relay 57 operates to drive the cooling fan 7 immediately after the engine generator 2 starts.

Further, the input side of the cooling fan 7 is connected to an emergency power source 14 via an inverter 15 in parallel with the generator 2b, and an emergency relay 58 is provided between the output of the inverter 15 and the controller 5. And a contact 55 d of the relay 55 is connected to a control input terminal of the inverter 15.

In such a configuration, when the engine generator 2 starts, the relay 5 is powered by the electric power from the generator 2b.
7, the contact 57a is closed, the relay 59 is operated and the contact 59a is closed, and the cooling fan 7 is driven. Then, when the voltage of the generator 2b reaches the set voltage,
When the switch 54 is closed, the relay 55 is activated and the contact 5
As soon as 5a and 55b are closed, the contact 55c opens and the relay 57 is turned off. When the contact 55b is closed, the relay 59 is kept operating, the cooling fan 7 is continuously driven, and when the contact 55a is closed, the amplifier 12 is operated. Also, the contact 55d
Opens, the inverter 15 is turned off,
The power supply to the controller 5 is switched from the emergency power supply 14 to the generator 2b by a relay 58.

Further, when the engine generator 2 is started, power may be supplied from the emergency power supply 14 to drive the cooling fan 7. That is, as shown in FIG. 3, instead of omitting the circuit between the preceding stage of the relay 55 and the cooling fan 7, the output side of the emergency power supply 14 is connected between the contacts 55b and 59a and the rotation speed is reduced. Sensor 51
The inverter 15 is operated when the engine generator 2 is driven based on the detected value from. Thus,
When the engine generator 2 is driven, the inverter 15 is operated, the emergency relay 58 is turned on, the contact 58a is closed, the relay 59 is turned on, and the cooling fan 7 is driven via the contact 59a. Then, when the voltage of the generator 2b reaches the set voltage, the relay 55 is activated and the contacts 55a and 55
At the same time as closing the contact 5b, the contact 55d is turned off and the inverter 15 is turned off, and the power supply to the cooling fan 7, the controller 5 and the like is performed by the emergency power supply 14 from the generator 2
b.

When the engine generator 2 is out of order, its output is lost, so that the relay 55 is turned off, the contact 55d is opened, and the inverter 15 is operated.
The DC from the emergency power supply 14 is converted into AC and output.
The emergency relay 58 is operated by this output, and electric power is supplied to the controller 5 and the cooling fan 7 to be driven.
In this way, the configuration is such that the residual heat in the duct 1 does not reach the speaker 3 via the branch pipe 9 and damage due to high heat is prevented. The relay 5 is connected to the power supply side of the cooling fan 7.
9, the contact 59b is connected in series with the power supply side of the amplifier 12, and the cooling fan 7 and the amplifier 12 are connected.
Is protected. Further, when power is supplied from the emergency power supply 14, the emergency relay 58 is operated and the contact 58b is opened, so that only necessary devices are supplied without supplying power to other devices, and wasteful power is not supplied. Like that.

[0026]

As described above, the present invention has the following advantages. That is, as in claim 1,
Means for outputting a muffling signal disposed downstream of the duct, means for cooling the muffling signal output means, and a muffling signal having an opposite phase to the noise signal detected by the first noise detection means. In an active silencer having a calculating means for calculating, and a second noise detecting means disposed downstream of the output means, an electric device and an active silencer are connected to a power output of the generator via a main switch. Since the power supply of the cooling unit was connected to the power supply of the apparatus and the power supply of the cooling means was connected to the preceding stage of the main switch via a power supply switching circuit, the power supply switching circuit was switched until the voltage of the generator rose to a set voltage. Power is supplied to the cooling means from the front stage of the switch and driven, and when the set voltage is reached, the power supply switching circuit is switched, and the cooling means can be driven from the rear stage of the main switch to cool the engine. The damaged can cool the muffler output unit can be prevented.

[0027] According to a second aspect of the present invention, first noise detecting means is provided in an exhaust duct of an engine of an engine generator, means arranged downstream of the duct to output a muffling signal, and said muffling signal output means is provided. Means for cooling, a calculating means for calculating a silencing signal having an opposite phase to the noise signal detected by the first noise detecting means, and a second noise arranged downstream from the output means. In an active silencer having a detecting means, an output power supply of the generator and an emergency power supply juxtaposed to an engine generator are connected in parallel to the cooling means via a power supply switching circuit, and when an engine generator fails, Since the power supply switching circuit is switched to supply power from the emergency power supply to drive the cooling means, the engine generator breaks down, especially when the engine is running but the generator breaks down. cold The cooling means is supplied with electric power from the emergency power supply even when not supplied with power means supposed to be continuously driven, it is of eliminating the muffler from being damaged by heat by residual heat.

Further, a first noise detecting means is provided in an exhaust duct of the engine of the engine generator, and a means for outputting a muffling signal is provided downstream of the duct.
Means for cooling the muffling signal output means, computing means for calculating a muffling signal having an opposite phase to the noise signal detected by the first noise detection means, and arranged downstream of the output means. An active noise reduction device having a second noise detection means, wherein an output power supply of the generator and an emergency power supply juxtaposed to an engine generator are connected to the cooling means via a power supply switching circuit to generate power. The power supply switching circuit is switched until the output power of the generator or the other generator is turned on, and the cooling means is driven by the power from the emergency power supply. Even if the power supply cannot be driven, the cooling means can be driven by the power from the emergency power supply, and the sound output means at startup can be prevented from being damaged by heat.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration and control of an active silencer of the present invention.

FIG. 2 is a block diagram illustrating a power supply switching circuit.

FIG. 3 is a block diagram of a power supply switching circuit that drives a cooling unit from an emergency power supply when the engine generator is started.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sound source passage duct 2 Engine generator 3 Speaker 4 First sound wave sensor 5 Controller 6 Second sound wave sensor 7 Cooling fan 14 Emergency power supply 50 Power supply switching circuit 54 Main switch

Claims (3)

[Claims] A first noise detection unit disposed in an exhaust duct of an engine of an engine generator, a unit arranged downstream of the duct to output a muffling signal, and a unit cooling the muffling signal output unit; A calculating means for calculating a noise canceling signal having an opposite phase to the noise signal detected by the first noise detecting means,
And an active silencer having a second noise detection means disposed downstream of the output means, wherein a power output of the generator is connected to a power supply of an electric device and an active silencer via a main switch. And a power supply for the cooling means is connected to a stage preceding the main switch via a power supply switching circuit. 2. A first noise detection means in an exhaust duct of an engine of an engine generator, a means arranged downstream of the duct to output a muffling signal, and a means for cooling the muffling signal output means. A calculating means for calculating a noise canceling signal having an opposite phase to the noise signal detected by the first noise detecting means,
And an active silencer having a second noise detection means disposed downstream of the output means, wherein a power supply is switched between an output power supply of the generator and an emergency power supply juxtaposed to the engine generator. An active silencer characterized in that the cooling means is connected in parallel to the cooling means via a circuit, and when the engine generator fails, the power supply switching circuit is switched to supply power from an emergency power supply to drive the cooling means. 3. A first noise detecting means in an exhaust duct of an engine of an engine generator, a means arranged downstream of the duct to output a muffling signal, and a means for cooling the muffling signal output means. A calculating means for calculating a noise canceling signal having an opposite phase to the noise signal detected by the first noise detecting means,
In the active silencer having a second noise detection unit disposed downstream of the output unit, the output power of the generator and the emergency power supply juxtaposed to the engine generator are switched. The cooling means is connected to the cooling means via a circuit, and the power supply switching circuit is switched until the output power of the generator or other generator is turned on, and the cooling means is driven by the power from the emergency power supply. Active silencer.