JP2007231917A - Noise controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce intake noise in a wide frequency band by utilizing sound waves generated on either one of vibration plates and sound waves generated on the other of them. <P>SOLUTION: This noise controller is provided with the vibration plates 11 for partitioning a silencer 15 into a main sound pressure generating chamber 13 and a back cavity 14 to suppress intake noise by the "synthetic waves" synthesized by main sound waves given into an intake pipe 2 from the main sound pressure generating chamber 13 and sub-sound waves given into the intake pipe 2 from the back cavity 14 by passing through a back cavity discharge passage 19. Since the sound waves generated in not only the main sound pressure generating chamber 13 but also the back cavity 14 are utilized in this way, quantity of energy to be consumed is suppressed. Since "primary frequency of explosion" and "frequency being multiple of the primary frequency of explosion" appear in the "synthetic wave" in the same way as in intake noise, the intake noise can be reduced in a wide frequency band. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a noise control device that suppresses intake noise of an internal combustion engine (hereinafter referred to as an engine).

As a noise control device that suppresses intake noise of an engine, a device that suppresses intake noise by generating a sound wave having a phase opposite to that of intake noise (sound wave generated in the intake passage) in the intake passage is known (for example, Patent Documents). 1).
However, the conventional technique uses only the sound wave generated in one of the diaphragms, and the sound wave generated in the other of the diaphragms, that is, the sound wave generated in the back cavity is not used, and is disposed in the back cavity. It is converted to heat or the like by a sound absorbing material or the like and is lost wastefully.
In addition, in order to avoid the problem that sound waves generated in the back cavity leak to the outside and become a new noise source, it is necessary to improve the sound deadening performance and sound insulation performance of the container for forming the back cavity (hereinafter referred to as a silencer). Yes, the silencer's physique becomes larger and heavier.
Japanese Patent Laid-Open No. 10-47182

  The present invention has been made in view of the above problems, and an object thereof is to reduce intake noise in a wide frequency range by using sound waves generated on one side of a diaphragm and sound waves generated on the other side of the diaphragm. The provision of noise control devices.

[Means of claim 1]
The noise control device adopting the means of claim 1 is a composite wave of a main sound wave given from the main sound pressure generating chamber to the intake passage and a sub sound wave given from the back cavity to the intake passage through the back cavity discharge passage. Suppresses intake noise.
That is, the intake noise can be suppressed using the sound wave generated in one of the diaphragms (the sound wave generated in the main sound pressure generating chamber) and the sound wave generated in the other of the diaphragms (sound generated in the back cavity).
Thus, since the sound wave generated in the back cavity can be used, the energy consumption of the diaphragm driving means for reciprocating the diaphragm can be suppressed.
In addition, since the sound waves (sound energy) generated in the back cavity is consumed and used to suppress intake noise, the silencer performance and sound insulation performance required of the silencer can be lowered, and the silencer can be made smaller and lighter. Can do.

The intake noise generated in the intake passage is composed of “explosion primary frequency (fundamental sound)” generated in the intake passage and “frequency that is a multiple of the explosion primary frequency”.
On the other hand, the sound wave generated by the noise control apparatus adopting the means of claim 1 is a “synthetic wave” of the main sound wave and the sub sound wave, and this “synthetic wave” has a phase opposite to that of the intake noise.
The main sound wave is a sound wave directly applied from the main sound pressure generating chamber into the intake passage, and the sub sound wave is a sound wave affected by the passage resistance of the back cavity discharge passage and the set load of the discharge one-way valve. is there. For this reason, in the “synthetic wave” of both, in addition to the “primary explosion frequency (opposite phase with respect to the intake noise)” as well as the intake noise, a frequency that is a multiple of the primary explosion frequency (intake air). Appears in antiphase with respect to noise).
Thus, the noise control apparatus employing the means of claim 1 generates “a frequency (reverse phase) that is a multiple of the explosion primary frequency” in addition to the “explosion primary frequency (reverse phase)”. Therefore, the “explosion primary frequency” and the “frequency that is a multiple of the explosion primary frequency” forming the intake noise can be canceled out.
That is, the noise control apparatus employing the means of claim 1 can reduce the intake noise in a wide frequency range.

[Means of claim 2]
The intake noise is a composite wave of “explosion primary frequency” and “multiple of explosion primary frequency”.
On the other hand, since the sound wave that cancels the intake noise is a combined wave of the main sound wave and the sub sound wave, the appearance of the multiple frequency generated in the combined wave changes when the combination of the main sound wave and the sub sound wave changes.

Therefore, the noise control apparatus employing the means of claim 2 is provided with an opening degree adjusting valve for adjusting the opening degree of the back cavity discharge passage.
Thereby, the passage resistance of the back cavity discharge passage can be adjusted.
By adjusting the passage resistance of the back cavity discharge passage in this way, during the combined wave of the main sound wave and the sub sound wave that changes depending on the “path resistance of the back cavity discharge passage” and the “set load of the one-way valve on the discharge side” It becomes possible to variably adjust the “frequency of the generated multiple”, and to efficiently suppress intake noise.

[Means of claim 3]
The back cavity suction passage of the noise control apparatus employing the means of claim 3 is connected to at least one of a canister for adsorbing and holding vaporized fuel or a crankcase via an oil mist separator.
When the diaphragm vibrates, the back cavity suction passage, the back cavity, and the back cavity discharge passage operate the air pump. For this reason, the vaporized fuel held in the canister or the blow-by gas in the crankcase is guided to the intake passage through the back cavity.
For this reason, even if the engine has a low negative pressure to reduce pump loss, vaporized fuel held in the canister and blow-by gas in the crankcase can be guided to the intake passage.

[Means of claim 4]
In the case of adopting the third aspect, the vaporized fuel (HC mixture) held in the canister and the blowby gas (HC mixture) in the crankcase pass through the opening adjustment valve of the back cavity discharge passage and the intake passage. Led to. Thus, when the HC mixture is guided to the intake passage, the air-fuel ratio of the engine combustion chamber changes when the concentration of the HC mixture guided to the intake passage changes.

Therefore, a noise control apparatus employing the means of claim 4 includes a differential pressure sensor for detecting a differential pressure between the upstream side and the downstream side of the opening adjustment valve.
The differential pressure across the valve is proportional to the density of the fluid passing through the valve. Therefore, it is possible to detect the concentration of the HC mixture guided from the back cavity discharge passage to the intake passage by detecting the differential pressure of the opening adjustment valve. This makes it possible to correct the injection amount injected from the injector based on the concentration of the HC mixture introduced into the intake passage, and to control the air-fuel ratio with high accuracy.

[Means of claim 5]
The diaphragm driving means of the noise control apparatus employing the means of claim 5 is a piezo actuator using a piezo element.
Although the piezoelectric actuator has a high driving voltage for the piezoelectric element, it can keep power consumption low.

[Means of claim 6]
The diaphragm driving means of the noise control apparatus adopting the means of claim 6 is a hydraulic actuator that is movable by switching of the hydraulic pressure.
Since a vehicle equipped with an engine is equipped with an oil pump serving as a hydraulic pressure source, the diaphragm can be driven by the hydraulic pressure discharged from the oil pump.
In addition, the capability of the oil pump can be applied as it is by providing the hydraulic actuator to be operated only when the hydraulic pressure is higher than a predetermined pressure. Further, by using wasted hydraulic pressure, energy consumption for driving the diaphragm can be suppressed.

[Means of Claim 7]
The diaphragm driving means of the noise control device adopting the means of claim 7 is a mechanical drive mechanism that is mechanically driven by the rotation of the engine.
Since the “primary explosion frequency”, which is the main component of intake noise, is a sound component that accompanies combustion, the sound wave that cancels intake noise (frequency opposite to the explosion primary frequency) depends on the crank angle of the engine. It corresponds. For this reason, the diaphragm can be mechanically driven by the rotation of the engine, and the intake noise can be canceled by the diaphragm.
Since the diaphragm is driven by the rotation of the engine, there is no need to install a new actuator on the vehicle.

[Means of Claim 8]
The diaphragm driving means of the noise control apparatus adopting the means of claim 8 includes an amplifying mechanism that amplifies the amplitude and transmits it to the diaphragm.
As a result, even if the amplitude generated by the piezo actuator, the hydraulic actuator or the mechanical drive mechanism is small, it is possible to obtain a sound pressure sufficient to cancel the intake noise by amplifying the amplitude.

The noise control device of the best mode 1 suppresses intake noise by generating a sound wave having a phase opposite to that of the sound wave generated in the intake passage of the engine.
The noise control device includes a diaphragm that generates a sound wave by vibration, a diaphragm driving unit that reciprocates the diaphragm, a main sound pressure generation chamber that communicates with an intake passage, and a sealed back cavity. A silencer that is partitioned, a back cavity that communicates with the back cavity and the outside of the back cavity, and is provided with a suction side one-way valve that allows air to flow only from the outside of the back cavity toward the back cavity, and the back cavity And a back cavity discharge passage provided with a discharge-side one-way valve that allows air to pass only from the back cavity toward the intake passage.
Then, the intake noise is suppressed by a composite wave of the main sound wave given from the main sound pressure generating chamber to the intake passage and the sub sound wave given from the back cavity to the intake passage through the back cavity discharge passage.

A noise control apparatus to which the present invention is applied will be described with reference to FIGS.
(Description of engine 1)
The engine 1 on which the noise control device is mounted is a well-known engine that repeats a cycle of intake, compression, explosion, and exhaust of air-fuel mixture for each cylinder, and includes an intake pipe 2.
The intake pipe 2 is a pipe that guides combustion air from the air suction port to the engine combustion chamber 1a in each cylinder, and is used for air filtration from the suction port side toward the downstream side (engine combustion chamber 1a side). An air cleaner 4 in which the air filter 3 is disposed, a throttle valve 5 for adjusting the intake air amount, and the like are provided. Reference numeral 6 shown in FIG. 1 is a return pipe that guides blow-by gas (HC mixture) in the cam cover 7 to the downstream side (clean side) of the air filter 3 in the air cleaner 4.

(Description of noise control device)
In the following, the noise control device will be described for each of a plurality of features.
First, the “first feature” constituting the basic configuration of the noise control device will be described.
The noise control device suppresses intake noise by generating a sound wave having a phase opposite to that of sound waves generated in the intake pipe 2 (intake passage). (A) A diaphragm 11 that generates sound waves by vibration; b) Silencer in which diaphragm 11 is partitioned by diaphragm 11 with diaphragm driving means 12 for reciprocatingly driving diaphragm 11, and (c) main sound pressure generation chamber 13 communicating with intake pipe 2 and sealed back cavity 14. 15, (d) a back cavity suction passage 17 provided with a suction side one-way valve 16 that communicates the back cavity 14 with the outside and allows air to flow only from the outside toward the back cavity 14, and (e) the back cavity. 14 and a back cavity discharge passage 19 provided with a discharge-side one-way valve 18 that communicates with the inside of the intake pipe 2 and passes air only from the back cavity 14 into the intake pipe 2. (F) a control device for controlling the operation of the diaphragm drive means 12 (not shown).
Below, said (a)-(f) is demonstrated separately.

(Description of diaphragm 11)
The diaphragm 11 is supported in a silencer 15 so as to be able to reciprocate while maintaining a state in which the main sound pressure generating chamber 13 and the back cavity 14 are partitioned. The diaphragm 11 is reciprocated by the diaphragm driving means 12 as described above. When the diaphragm 11 moves to the main sound pressure generating chamber 13 side, the main sound pressure generating chamber 13 is compressed and the back cavity 14 is expanded. On the contrary, when the diaphragm 11 moves to the back cavity 14 side, the main sound pressure generating chamber 13 is expanded and the back cavity 14 is compressed. That is, the diaphragm 11 is driven to reciprocate at a sound wave frequency by the diaphragm driving means 12, so that a sound pressure wave is generated in each of the main sound pressure generating chamber 13 and the back cavity 14.

(Description of diaphragm driving means 12)
The diaphragm driving means 12 includes a piezoelectric actuator 21 using a piezoelectric element (piezoelectric element: not shown) and an amplification mechanism 22 that amplifies the amplitude generated by the piezoelectric actuator 21 and transmits the amplified amplitude to the diaphragm 11.
The piezo actuator 21 is an example of a well-known electric actuator that outputs a displacement amount by performing deformation, expansion, and contraction of a piezo element by charging and discharging, and charge / discharge control is performed by a control device.
Specifically, the piezo actuator 21 of this embodiment is formed by laminating a large number of piezo elements, and the amount of expansion and contraction of the piezo actuator 21 is changed by charging and discharging.

Since the amount of expansion / contraction of one piezo element is very small (for example, several tens of μm), the expansion / contraction amount is small even in the piezo actuator 21 in which a large number of piezo elements are stacked. Even if is driven, a sound pressure sufficient to cancel out the intake noise cannot be obtained.
The amplifying mechanism 22 employs a displacement enlarging means that enlarges the amount of expansion / contraction of the piezo actuator 21 and transmits it to the diaphragm 11. Specifically, the amplification mechanism 22 includes a large-diameter chamber 23 and a small-diameter chamber 24 filled with oil, a piston 25 capable of changing the volume of the large-diameter chamber 23, and the piston 25 as a piezoelectric actuator. The return spring 26 is pressed in the displacement direction 21. A shaft 27 that moves integrally with the diaphragm 11 is inserted into the small diameter chamber 24, and the diaphragm 11 is driven when the volume of the small diameter chamber 24 changes. The oil in the oil chamber is sealed so as not to leak to the outside of the oil chamber by a sealing material or the like (not shown).

The operation of the diaphragm driving means 12 will be described.
When the piezo element of the piezo actuator 21 is charged by the control device, the piezo actuator 21 extends and the piston 25 moves to the side of reducing the volume of the large-diameter chamber 23. Then, the expansion ratio of the piezoelectric actuator 21 is amplified and transmitted to the diaphragm 11 by the diameter ratio of the large diameter chamber 23 and the small diameter chamber 24, and the diaphragm 11 moves to the main sound pressure generating chamber 13 side.
Conversely, when the piezo element of the piezo actuator 21 is discharged by the control device, the piezo actuator 21 contracts due to the urging force of the return spring 26 and the piston 25 moves to the side of enlarging the volume of the large-diameter chamber 23. Then, the contraction amount of the piezo actuator 21 is amplified by the diameter ratio of the large-diameter chamber 23 and the small-diameter chamber 24 and transmitted to the diaphragm 11, and the diaphragm 11 moves to the back cavity 14 side.

(Description of silencer 15)
The silencer 15 is a container in which the above-described diaphragm 11 is reciprocally driven, and the main sound pressure generation chamber 13 defined by the diaphragm 11 is directly or via a duct or the like on the clean side in the air cleaner 4. Communicate.
In this embodiment, the main sound pressure generating chamber 13 of the silencer 15 is communicated with the clean side in the air cleaner 4, but is communicated with the intake port side of the intake pipe 2 serving as an outlet for intake noise. As long as it is in the intake pipe 2, it may be communicated anywhere.

(Description of back cavity suction passage 17)
The back cavity suction passage 17 is externally connected to a canister (to be described later) when the back cavity 14 becomes negative pressure (when the diaphragm 11 moves to the main sound pressure generating chamber 13 side and the back cavity 14 is expanded). 31 is a pipe for introducing air (HC mixture to be described later) from the inside of the crankcase 33 through the oil mist separator 35 into the back cavity 14.

  The suction-side one-way valve 16 provided in the back cavity suction passage 17 allows air to flow only from the outside (in the canister 31 described later, in the crankcase 33 via the oil mist separator 35) toward the back cavity 14. Yes, the valve is opened when the back cavity 14 becomes negative pressure, and air is introduced into the back cavity 14 from the outside. On the contrary, when the back cavity 14 becomes positive pressure (when the diaphragm 11 moves to the back cavity 14 side and the back cavity 14 is compressed), the valve is closed and the air in the back cavity 14 is outside. This prevents backflow into the canister 31 (described later, in the crankcase 33 via the oil mist separator 35).

(Description of back cavity discharge passage 19)
The back cavity discharge passage 19 is a pipe that guides the air compressed in the back cavity 14 to the clean side in the air cleaner 4 when the back cavity 14 becomes positive pressure.
The outlet opening of the back cavity discharge passage 19 is opened in the vicinity of the communication portion between the main sound pressure generating chamber 13 and the intake pipe 2, and the main sound wave applied from the main sound pressure generating chamber 13 into the intake pipe 2; The sub-sonic wave applied from the back cavity 14 to the intake pipe 2 through the back cavity discharge passage 19 is synthesized in the intake pipe 2.

  The discharge-side one-way valve 18 provided in the back cavity discharge passage 19 allows air to flow only from the back cavity 14 into the intake pipe 2, and when the back cavity 14 becomes positive pressure (specifically, Is opened when the positive pressure of the back cavity 14 is higher than the set load of the discharge-side one-way valve 18, and guides the air compressed in the back cavity 14 into the intake pipe 2. Conversely, when the back cavity 14 becomes negative pressure, the valve is closed to prevent the air in the intake pipe 2 from flowing back to the back cavity 14.

(Description of control device)
The control device controls charging / discharging of the piezo actuator 21 of the diaphragm driving means 12, and controls the charge / discharge amount / charge / discharge cycle / charge / discharge timing of the piezo actuator 21 according to the operating state of the engine 1. The sound pressure, frequency, and phase of the “synthesized wave” of the main sound wave and the sub sound wave generated in the intake pipe 2 are controlled.
Here, the “intake noise” is composed of “a sound wave having an explosion primary frequency” and “a sound wave having a frequency that is a multiple of the explosion primary frequency”.
Of the “intake noise” generated in the intake pipe 2, the “explosion primary frequency sound wave” relates to the engine speed, and the “explosion primary frequency phase” refers to the opening of the intake valve 1 b. Involved in timing.
On the other hand, the “synthetic wave” of the main sound wave and the sub sound wave generated by the noise control device is generated based on a charge / discharge signal given to the piezo actuator 21 by the control device.

The control device is a piezo actuator so that the noise control device generates “synthetic wave” in the opposite phase to “sound wave of primary explosion frequency” of “intake noise” generated in the intake pipe 2. 21 is controlled.
Specifically, the control device controls charging / discharging of the piezo actuator 21 based on a “crank angle rotation signal” given from an engine ECU (not shown).
More specifically, the control device corrects the charge / discharge timing of the piezo actuator 21 with reference to a map of the phase lag according to the engine rotational speed and the communication part of the silencer 15 and the intake pipe 2 (part where the intake noise is canceled). Then, a “synthetic wave” having an opposite phase to the “exponment primary frequency sound wave” of the “intake noise” generated in the intake pipe 2 is generated in the intake pipe 2.

The control device according to this embodiment includes a correction function for always setting the “composite wave” to an opposite phase with respect to the “explosion primary frequency sound wave” generated in the intake pipe 2.
If “synthetic wave” is generated in the opposite phase with respect to the “explosion primary frequency sound wave” generated in the intake pipe 2, on the clean side of the air cleaner 4 (the communication part of the silencer 15 and the intake pipe 2), Pressure pulsation that becomes intake noise is reduced. However, the effect of reducing pressure pulsation is weakened when the “synthetic wave” deviates from the opposite phase with respect to the “exponment primary frequency sound wave”.
The control device uses this action to correct the generation time of the “synthetic wave”, and the control device is connected to a pressure sensor 28 for detecting pressure pulsations on the clean side of the air cleaner 4. Then, when the pressure pulsation detected by the pressure sensor 28 is larger than the target level for a preset engine operating state (the pressure pulsation is large), the control apparatus determines that the pressure pulsation detected by the pressure sensor 28 is the minimum. Thus, the charge / discharge timing of the piezoelectric actuator 21 is corrected.

(First effect)
As described above, the noise control apparatus according to the present embodiment applies the main sound wave applied from the main sound pressure generating chamber 13 into the intake pipe 2 and the back sound from the back cavity 14 through the back cavity discharge passage 19 into the intake pipe 2. Inhalation noise is suppressed by the "synthetic wave" with the sub sound wave. That is, the intake noise is suppressed by using the sound wave generated in one of the diaphragms 11 (the sound wave generated in the main sound pressure generating chamber 13) and the sound wave generated in the other part of the diaphragm 11 (sound generated in the back cavity 14).
Thus, since the sound wave generated not only from the main sound pressure generating chamber 13 but also from the back cavity 14 can be used, energy consumption of the diaphragm driving means 12 that reciprocally drives the diaphragm 11 can be suppressed. it can.
In addition, since sound waves (sound energy) generated in the back cavity 14 are utilized and consumed for suppressing intake noise, the silencer performance and sound insulation performance required for the silencer 15 constituting the back cavity 14 can be lowered, and the silencer 15 can be reduced in size and weight.

(Second effect)
As described above, the “intake noise” generated in the intake pipe 2 is composed of “explosion primary frequency (fundamental sound)” and “frequency that is a multiple of the explosion primary frequency”.
On the other hand, the sound wave generated by the noise control device of the present embodiment is a “synthetic wave” of the main sound wave and the sub sound wave, and this “synthetic wave” has a phase opposite to that of the intake noise.
The main sound wave is a sound wave directly given from the main sound pressure generating chamber 13 into the intake pipe 2, and the sub sound wave is influenced by the passage resistance of the back cavity discharge passage 19 and the set load of the discharge side one-way valve 18. It is the sound wave that receives. The “synthetic wave” generated in this way includes a frequency that is a multiple of the primary explosion frequency in addition to the primary explosion frequency (opposite phase with respect to the intake noise), similarly to the intake noise. (Inverse phase with respect to intake noise) "appears.
As described above, the noise control apparatus according to the present embodiment generates “a frequency (reverse phase) that is a multiple of the primary explosion frequency” in addition to the “primary explosion frequency (reverse phase)”. The “explosion primary frequency” and the “multiple of the explosion primary frequency” can be canceled out. That is, the noise control device can reduce intake noise in a wide frequency range.

[Second feature]
As described above, the “synthetic wave” generated by the noise control apparatus of the present embodiment includes a frequency (an antiphase) that is a multiple of the primary explosion frequency (an antiphase) in addition to the “primary explosion frequency (the antiphase)”. ) ". One main sound wave of the synthesized wave is a sound wave directly given from the main sound pressure generating chamber 13 into the intake pipe 2, and the other sub sound wave of the synthesized wave is the resistance of the back cavity discharge passage 19 and the discharge. The sound wave is affected by the set load of the side one-way valve 18.
Here, if at least one of the passage resistance of the back cavity discharge passage 19 or the set load of the discharge side one-way valve 18 is changed, the degree of generation of the sub sound wave changes. Then, by changing the generation state of the sub sound wave, it is possible to change the appearance of the “frequency that is a multiple of the explosion primary frequency (reverse phase)”.

A specific example of the above will be described with reference to FIG. In the figure, the waveform of the main sound wave is indicated by a solid line A, the waveform of the sub sound wave is indicated by a solid line B, and the waveform of the synthesized wave is indicated by a solid line C.
FIG. 2A shows an example in which the set load of the discharge-side one-way valve 18 is increased and the phase of the sub sound wave B is delayed by 45 ° with respect to the main sound wave A. With this setting, the composite wave C includes “explosion primary frequency” and “frequency that is an integral multiple of the explosion primary frequency” as shown in FIG.
FIG. 2B shows an example in which the set load of the discharge-side one-way valve 18 is set to approximately 0 (zero), and the phase of the sub sound wave B is delayed by 135 ° with respect to the main sound wave A. With this setting, the composite wave C includes “explosion primary frequency” and “an even multiple of the explosion primary frequency” as shown in FIG.

By utilizing the above-described action, the noise control device of this embodiment changes the degree of generation of the sub sound wave, and includes “a frequency (reverse phase) that is a multiple of the primary explosion frequency” included in the “synthetic wave”. Is changed, and “frequency of the first explosion frequency (reverse phase)” included in the “synthetic wave” is changed to a frequency (multiple of the first explosion frequency included in the intake noise (positive phase). ) "Is provided in order to further reduce the intake noise.
Specifically, the noise control apparatus according to this embodiment changes the generation state of the sub sound waves, and changes the appearance of “a frequency that is an integral multiple of the explosion primary frequency (opposite phase)” as a back cavity. An opening adjustment valve 29 that changes the passage resistance of the back cavity discharge passage 19 by adjusting the opening of the discharge passage 19 is provided.

  Then, by adjusting the opening degree of the opening adjustment valve 29, the passage resistance of the back cavity discharge passage 19 is adjusted, and the generation state of the sub sound wave is changed, so that “in the combined wave of the main sound wave and the sub sound wave” Can be variably adjusted, and intake noise can be efficiently suppressed.

[Third feature]
The back cavity suction passage 17 of the noise control device of the present embodiment communicates with the inside of a canister 31 that holds vaporized fuel in a fuel tank (not shown) via a canister outlet pipe (evaporation line) 32, and in the engine combustion chamber 1a. Is communicated with the inside of the crankcase 33 from which the blow-by gas leaks through the crankcase connecting pipe (blow-by line) 34. The crankcase connection pipe 34 is provided with an oil mist separator 35 that separates oil mist contained in blow-by gas.

When the diaphragm 11 is vibrated by the operation of the noise control device, the back cavity suction passage 17, the back cavity 14, and the back cavity discharge passage 19 operate the air pump. Therefore, the vaporized fuel (HC mixture) held in the canister 31 or the blowby gas (HC mixture) in the crankcase 33 is guided into the intake pipe 2 via the back cavity 14.
For this reason, even if the engine 1 has a low negative pressure to reduce pump loss, the vaporized fuel (HC mixture) held in the canister 31 and the blow-by gas (HC mixture) in the crankcase 33 are sucked. It can be led to the tube 2. For this reason, it is possible to avoid the trouble that blow-by gas blown into the crankcase 33 from the engine combustion chamber 1a is discharged into the atmosphere or the blow-by gas deteriorates engine oil.

[Fourth feature]
In the noise control device of the present embodiment, the vaporized fuel (HC mixture) held in the canister 31 and the blow-by gas (HC mixture) in the crankcase 33 are provided in the back cavity discharge passage 19. It is guided into the intake pipe 2 through the adjustment valve 29.
Here, when the HC mixture is introduced into the intake pipe 2, the air-fuel ratio in the engine combustion chamber 1a changes due to the concentration change of the HC mixture.

Therefore, the noise control device according to the present embodiment detects the differential pressure between the upstream side and the downstream side of the opening adjustment valve 29 in order to detect the concentration of the HC mixture introduced into the intake pipe 2. It has.
The differential pressure across the valve is proportional to the density of the fluid passing through the valve. For this reason, by detecting the differential pressure of the opening adjustment valve 29, the concentration of the HC mixture introduced into the intake pipe 2 from the back cavity discharge passage 19 can be detected. The engine ECU calculates the concentration of the HC mixture introduced into the intake pipe 2 from the differential pressure detected by the differential pressure sensor 36, and corrects the injection amount injected from the injector based on the calculated HC concentration. Thus, the air-fuel ratio can be controlled with high accuracy.

[Fifth feature]
As described above, the noise control apparatus according to the present embodiment uses the piezo actuator 21 as the drive source of the diaphragm drive unit 12.
Although the piezo actuator 21 has a high drive voltage for the piezo element, the power consumption can be kept low. Thereby, the power consumption of the noise control device can be suppressed. That is, intake noise can be reduced with less power consumption.

[Sixth feature]
As described above, the diaphragm driving unit 12 in the noise control device of the present embodiment includes the amplification mechanism 22 that amplifies the output (amplitude) of the piezoelectric actuator 21 and transmits the amplified output to the diaphragm 11.
As a result, even if the expansion / contraction amount of the piezo actuator 21 is small, it is possible to obtain a sound pressure sufficient to cancel the intake noise by amplifying the expansion / contraction amount (amplitude).

[Modification]
In the above-described embodiment, the example in which the piezo actuator 21 is used as the drive source of the diaphragm driving unit 12 has been described, but other vibration generators may be used.
As a specific example, a hydraulic actuator that can be moved by switching hydraulic pressure may be used as the drive source of the diaphragm driving means 12.
The vehicle is equipped with an oil pump as a hydraulic source. For this reason, the diaphragm 11 can be driven by the hydraulic pressure discharged from the oil pump. Thereby, an energy source for canceling the intake noise can be easily secured. In this case, the hydraulic actuator may be provided only when the hydraulic pressure is higher than a predetermined pressure. By providing in this way, the capability of the oil pump can be applied as it is. Further, by using wasted hydraulic pressure, energy consumption for driving the diaphragm 11 can be suppressed.

As another specific example, a mechanical drive mechanism that mechanically drives the diaphragm 11 by rotation of the engine 1 may be used as a drive source of the diaphragm drive unit 12.
The “primary explosion frequency” that is the main component of the intake noise is a sound component that accompanies combustion, and the sound wave that cancels the intake noise (frequency opposite in phase to the explosion primary frequency) is at the crank angle of the engine 1. It corresponds. For this reason, the diaphragm 11 can be mechanically driven by the rotation of the engine 1, and the intake noise can be canceled by the diaphragm 11.
Since the diaphragm 11 is driven by the rotation of the engine 1, it is not necessary to additionally mount a new actuator on the vehicle.

  In the above-described embodiment, the example in which the vaporized fuel of the canister 31 and the blow-by gas in the crankcase 33 are guided into the intake pipe 2 by the operation of the noise control device has been shown, but the back cavity suction passage 17 and the cam cover 7 May be provided so as to guide the blow-by gas in the cam cover 7 into the intake pipe 2.

It is a schematic block diagram of a noise control apparatus. It is explanatory drawing of how to show "the frequency of the multiple of the explosion primary frequency" which arises in the synthetic wave of a main sound wave and a subsonic wave.

Explanation of symbols

1 engine (internal combustion engine)
2 Intake pipe (pipe that forms the intake passage)
DESCRIPTION OF SYMBOLS 11 Diaphragm 12 Diaphragm drive means 13 Main sound pressure generation chamber 14 Back cavity 15 Silencer 16 Suction side one-way valve 17 Back cavity suction passage 18 Discharge side one way valve 19 Back cavity discharge passage 21 Piezo actuator 22 Amplifying mechanism 29 Opening degree Adjustment valve 31 Canister 33 Crankcase 35 Oil mist separator 36 Differential pressure sensor

Claims (8)

In a noise control device that suppresses intake noise by generating a sound wave having an opposite phase to the sound wave generated in the intake passage of the internal combustion engine,
This noise control device
A diaphragm that generates sound waves by vibration;
Diaphragm driving means for reciprocating the diaphragm;
A silencer in which a main sound pressure generating chamber communicating with the intake passage and a sealed back cavity are partitioned by the diaphragm;
A back cavity suction passage provided with a suction side one-way valve that communicates the back cavity and the outside of the back cavity, and allows air to flow only from the outside of the back cavity toward the back cavity;
A back cavity discharge passage provided with a discharge-side one-way valve that communicates the back cavity and the intake passage and allows air to pass only from the back cavity toward the intake passage;
Suppressing intake noise by a combined wave of a main sound wave given from the main sound pressure generating chamber to the intake passage and a sub sound wave given from the back cavity through the back cavity discharge passage to the intake passage. A characteristic noise control device. The noise control device according to claim 1,
This noise control device
A noise control device comprising an opening adjustment valve for adjusting the opening of the back cavity discharge passage. The noise control device according to claim 2,
The noise control device according to claim 1, wherein the back cavity suction passage is connected to at least one of a canister for adsorbing and holding vaporized fuel or a crankcase via an oil mist separator. The noise control device according to claim 3,
This noise control device
A noise control device comprising a differential pressure sensor for detecting a differential pressure between an upstream side and a downstream side of the opening adjustment valve. In the noise control device according to any one of claims 1 to 4,
The noise control apparatus, wherein the diaphragm driving means is a piezo actuator using a piezo element. In the noise control device according to any one of claims 1 to 4,
The noise control device according to claim 1, wherein the diaphragm driving means is a hydraulic actuator that is movable by switching hydraulic pressure. In the noise control device according to any one of claims 1 to 4,
The noise control apparatus according to claim 1, wherein the diaphragm driving means is a mechanical drive mechanism that is mechanically driven by rotation of the internal combustion engine. In the noise control device according to any one of claims 5 to 7,
The noise control apparatus, wherein the diaphragm driving means includes an amplification mechanism that amplifies an amplitude and transmits the amplified amplitude to the diaphragm.

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