JPH0536013U - Intake / exhaust noise reduction device for internal combustion engine - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a device for effectively canceling intake and exhaust noises of an internal combustion engine. [Structure] Two diaphragm chambers 21 and 22 are defined by a diaphragm 20, and one diaphragm chamber 21 receives a pressure wave guided from the intake pipe 2 through an intake waveguide 23 and the other diaphragm chamber 22. In the intake / exhaust noise reduction device guided from the exhaust pipe 5 through the exhaust waveguide 24,
A plurality of intake waveguides 23a, 23b connected to the upstream side and the downstream side of the throttle valve 4 with respect to the intake pipe 2, respectively.
And a switching means 29 using the intake waveguides 23a and 23b which are opened in a portion having a high sound pressure according to the operating conditions.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an intake / exhaust noise reduction device for an internal combustion engine.

[0002]

[Prior Art]

 In automobiles, etc., as the quietness of the engine body improves. There is an increasing demand for reduction of intake and exhaust noise.

As a countermeasure against this, for example, in Japanese Utility Model Laid-Open No. 63-11379, a microphone and a speaker are attached in the middle of an intake pipe, and a sound pressure signal detected from the microphone and a phase signal from a crank angle sensor are controlled by a control unit. To the speaker to obtain the amplitude and phase of the sound that is in the opposite phase to the intake sound, send this information to the speaker, and the speaker has almost the same amplitude as the intake sound and has the opposite phase. It has been proposed to reduce the intake sound by generating the sound wave of.

Since the intake sound is mainly regarded as a pressure wave caused by pressure pulsation associated with opening and closing of an intake valve, if a pressure wave of the same frequency and an opposite phase can be applied to cancel this pressure wave, It is known that both waves interfere with each other and cancel each other out, weakening the amplitude or sound pressure of the waves.

[0005]

[Problems to be solved by the device]

 However, in such a conventional device, since the same sound pressure as the intake sound is produced by the speaker, a sound pressure equivalent to the intake sound of 130 to 150 dB generated at the engine full load state is generated by the speaker. In such a case, a speaker output of 100 W or more is required, which not only causes an increase in the size of the speaker, resulting in an increase in weight and deterioration of mountability in a vehicle, but also an increase in power consumption for driving the speaker.

The present invention focuses on the above points, and an object thereof is to effectively cancel intake and exhaust sounds by utilizing intake and exhaust pulsations instead of a speaker.

[0007]

[Means for Solving the Problems]

 The present invention has two diaphragm chambers defined by a diaphragm that responds to pressure, an intake waveguide that guides a pressure wave generated in the intake pipe to one diaphragm chamber, and a pressure generated in the exhaust pipe to the other diaphragm chamber. In an intake / exhaust noise reduction system for an internal combustion engine equipped with an exhaust waveguide that guides waves, a plurality of intake waveguides that are connected to the intake pipe upstream and downstream of the throttle valve, respectively, And a switching means using an intake waveguide that opens to a portion having a high sound pressure.

[0008]

[Action]

 When the intake and exhaust valves are opened and closed at a predetermined timing in synchronization with the engine rotation, pressure waves are generated in the intake pipe and the exhaust pipe, respectively. The pressure wave generated in the intake pipe is guided to one diaphragm chamber via the intake waveguide, and the pressure wave generated in the exhaust pipe is guided to the other diaphragm chamber via the exhaust waveguide. By introducing pressure waves of opposite phase to each diaphragm chamber, both pressure waves interfere and cancel each other through the diaphragm that responds to the pressure, and the amplitude of the wave, that is, the sound pressure is weakened.

During operation in a low to medium load range where the opening of the throttle valve is small, the chamber inside the throttle valve is throttled, so that the sound pressure of the pressure wave generated in the intake pipe becomes higher on the upstream side of the slot valve. .. Under this operating condition, the intake sound is effectively attenuated in the high sound pressure portion by using the waveguide connected to the upstream side of the slot valve via the switching means.

When the throttle valve is fully opened at full load, the chamber in which the throttle valve is inserted becomes a substantially cylindrical space, so that the sound pressure of the pressure wave generated in the intake pipe is downstream of the throttle valve and closer to the cylinder. Grows on the side. Under this operating condition, the intake sound is effectively canceled in the high sound pressure portion by using the intake waveguide connected to the downstream side of the throttle valve via the switching means.

[0011]

【Example】

 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, an intake pipe 2 of a multi-cylinder engine 1 includes a plurality of branch portions 11 that communicate with each cylinder via an intake valve 3, and a collector portion 12 that collects the branch portions 11. , A duct part 13 connecting the collector part 12 and the air cleaner 14, and a duct part 15 for introducing outside air into the air cleaner 14, and a throttle valve 4 is interposed between the collector part 12 and the air cleaner 14 to adjust the intake amount. To be done.

The exhaust pipe 5 guides the exhaust gas discharged from each cylinder to the outside when the exhaust valve 6 is opened, and a catalyst converter and a silencer (not shown) are interposed in the middle thereof.

A first diaphragm actuator 7 and a second diaphragm actuator 8 are provided between the intake pipe 2 and the exhaust pipe 5. Each of the diaphragm actuators 7 and 8 includes a diaphragm 20 that functions as a movable film that responds to pressure, and the diaphragm 20 defines two diaphragm chambers 21 and 22. A spring 25 that elastically supports the diaphragm 20 is interposed in the diaphragm chamber 22.

The first diaphragm actuator 7 communicates with each of the branch parts 11 on the downstream side of the throttle valve 4 and guides a pressure wave generated in the intake pipe 2 to one diaphragm chamber 21 and an exhaust waveguide 23 a. An exhaust waveguide 24 that guides the pressure wave generated in 5 to the other diaphragm chamber 22 is connected.

The second diaphragm actuator 8 communicates with the duct part 13 upstream of the throttle valve 4 and guides the pressure wave generated in the intake pipe 2 to one diaphragm chamber 21 and the intake waveguide 23 b and the exhaust pipe 5. Is connected to the exhaust waveguide 24 that guides the pressure wave generated in the other diaphragm chamber 22 to the other diaphragm chamber 22.

The openings of the intake waveguides 23a and 23b with respect to the intake pipe 2 are located at positions where the sound pressure is high in the rotation region where the resonance of the pressure wave occurs in the intake pipe 2, that is, the antinode portion of the standing wave comes. Will be placed. In this embodiment, the opening portion of each intake waveguide 23 with respect to the intake pipe 2 is at 70 to 120 Hz, where intake and exhaust noise may propagate into the vehicle interior to generate a muffled sound in an operating state after warming up. They are placed at the locations where the sound pressure is high with respect to the pressure waves that resonate in the low frequency range.

The volume of the intake / exhaust system and the pipe length are set so that the pressure wave of the intake pipe 2 and the pressure wave of the exhaust pipe 5 have substantially the same resonance frequency in the frequency range of 70 to 120 Hz. Is set appropriately.

As a switching means for selectively using the intake waveguides 23a and 23b which are opened in a portion having a high sound pressure according to the operating conditions, the exhaust waveguide 24 communicating with the exhaust pipe 5 is a first diaphragm actuator 7. Has a first branch pipe part 27 communicating with the second diaphragm actuator 8 and a second branch pipe part 28 communicating with the second diaphragm actuator 8, and selectively opens the first branch pipe part 27 and the second branch pipe part 28. A switching valve 29 is provided. A motor 30 for switching and driving the switching valve 29 and a control unit 31 for driving the motor 30 are provided to selectively open the branch pipes 27 and 28 in accordance with engine operating conditions.

A sensor 32 for detecting the opening degree K of the throttle valve 4 and a crank angle sensor 33 for detecting the rotational speed Ne of the engine are provided. These detection signals are control unit 31 including a microcomputer as a control means. Entered in. These detected values K and Ne are values representative of operating conditions related to the position where the sound pressure mode of the intake pipe 2 becomes high.

The control unit 31 causes the CPU to calculate the position where the sound pressure mode of the intake pipe 2 becomes high according to the detected values K and Ne. These characteristics are obtained by experiments and stored in a memory (eg ROM) in advance. Based on this calculated value, the pressure wave of the exhaust pipe 5 is introduced into one of the diaphragm actuators 7 and 8 that has the intake waveguide 23a or the intake waveguide 23b that opens at a position with a high sound pressure. The position of the switching valve 29 is switched.

With such a configuration, when the intake valve 3 and the exhaust valve 6 are opened and closed at a predetermined timing in synchronization with the rotation of the crankshaft 9, pressure waves are generated in the intake pipe 2 and the exhaust pipe 5, respectively. Both pressure waves have the same frequency, the pressure wave generated in the intake pipe 2 is guided to each diaphragm chamber 21 through the intake waveguide 23a or the intake waveguide 23b, and the pressure wave generated in the exhaust pipe 5 is generated. Are guided to each diaphragm chamber 22 via the exhaust waveguide 24. By introducing pressure waves of opposite phases to the respective diaphragm chambers 21 and 22, both pressure waves interfere and cancel each other through the diaphragm 20 that responds to the pressure, and the amplitude of the wave, that is, the sound pressure is weakened.

When the throttle valve 4 is fully opened, the flow path in the chamber in which the throttle valve 4 is inserted becomes a substantially cylindrical straight pipe, and the sound pressure of the pressure wave generated in the intake pipe 2 is transferred to the cylinder from the slot valve 4. It becomes large on the downstream side. Under this operating condition, the switching valve 29 opens one of the branch pipe portions 27, and the first diaphragm actuator 7 uses the intake waveguide 23a opened to a portion having a high sound pressure to effectively attenuate the intake sound. ..

When the opening of the throttle valve 4 is small in the low to medium load range, the flow path in the chamber in which the throttle valve 4 is interposed is throttled, so the sound pressure of the pressure wave generated in the intake pipe 2 is It becomes larger on the upstream side. Under this operating condition, the switching valve 29 opens the other branch pipe portion 28, and the second diaphragm actuator 8 effectively attenuates the intake sound by using the intake waveguide 23b which opens to a portion having a high sound pressure.

In this embodiment, the resonance frequencies of the intake sound and the exhaust sound are substantially matched in the low frequency range of 70 to 120 Hz where the intake and exhaust sounds may propagate into the vehicle interior and generate muffled sounds. As a result, the resonance energy is used to cancel each other out, and in cooperation with the switching control of each of the diaphragm actuators 7 and 8 described above, the muffled noise in the vehicle interior caused by the intake and exhaust noise is significantly reduced, and the noise is emitted to the outside of the vehicle. Can effectively reduce the noise.

Since each of the diaphragm actuators 7 and 8 is smaller than the speaker of the conventional device, it can be easily mounted on the vehicle and is advantageous in cost.

[0027]

[Effect of the device]

 As described above, the present invention has two diaphragm chambers defined by a diaphragm that responds to pressure, a waveguide that guides the pressure wave generated in the intake pipe to one diaphragm chamber, and the other diaphragm chamber to the other diaphragm chamber. In an intake / exhaust noise reduction device for an internal combustion engine, which comprises an exhaust waveguide that guides a pressure wave generated in an exhaust pipe, a plurality of intake waveguides that are respectively connected to an intake pipe upstream and downstream of a throttle valve, Switching means that uses an intake waveguide that opens in a region with high sound pressure according to operating conditions is provided, so it can be easily installed on the vehicle and the intake and exhaust sounds can be effectively handled in response to load fluctuations. Can be offset.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

[Explanation of symbols]

 1 Engine 2 Intake Pipe 4 Throttle Valve 5 Exhaust Pipe 7 First Diaphragm Actuator 8 Second Diaphragm Actuator 20 Diaphragm 21 Diaphragm Chamber 22 Diaphragm Chamber 23a Intake Waveguide 23b Intake Waveguide 24 Exhaust Waveguide 27 Branch Pipe 28 Branch Pipe section 29 Switching valve 31 Control unit 32 Throttle valve opening sensor 33 Crank angle sensor

Claims (1)

[Scope of utility model registration request] 1. A two-diaphragm chamber defined by a diaphragm responsive to pressure, an intake waveguide for guiding a pressure wave generated in the intake pipe to one diaphragm chamber, and a pressure generated in an exhaust pipe in the other diaphragm chamber. In an intake / exhaust noise reduction device for an internal combustion engine, which comprises an exhaust waveguide that guides waves, a plurality of intake waveguides that are respectively connected to an intake pipe upstream and downstream of a throttle valve, An intake / exhaust noise reduction device for an internal combustion engine, comprising: a switching means that uses an intake waveguide that opens to a portion having a high sound pressure.