JPS593157A - Noise reduction device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To efficiently reduce an intake air noise over the entire range of engine rotation, by connecting a plurality of resonance chambers of different volumes through a passage provided with a switch valve to an engine intake system on the way thereof, and controlling the valve in response to engine speeds to select any appropriate resonance chamber. CONSTITUTION:A plurality of resonance chambers 6a-6c having different volumes are connected through a communication passage 4 and a rotary valve 5 to an intermediate position of an outside air intake passage 3 leading to an air cleaner 2 mounted on an internal-combustion engine 1. An engine speed sensor 7 for outputting a signal responsive to rotational speeds of a crank shaft is mounted in the engine 1. Such an output is fed to a controller 8, and thereby the rotary valve 5 is selectively operated by a motor 9 in response to the engine speeds. Accordingly, the resonance chambers 6a-6c leading to the outside air intake passage 3 are selected by selectively operating the rotary valve 5 responsive to the rotational speeds of the engine 1, thereby efficiently reducing an intake air noise over the entire range of engine rotation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a noise reduction device for an internal combustion engine.

In order to reduce the noise of internal combustion engines, various devices have been proposed and put into practical use. In other words, a muffler is used to reduce exhaust noise, an intake resonator is used to reduce intake noise, and an engine enclosure is used to reduce noise radiated from the engine itself, all of which achieve a certain effect. ing.

However, in conventional intake resonators, the volume of the resonance chamber is fixed, so although intake noise in a specific rotation range can be reduced, in engines with a wide rotation range such as automobile engines, it is difficult to sufficiently reduce intake noise over the entire practical rotation range. could not be reduced.

In order to solve this situation, it is possible to variably control the volume of the resonance chamber in response to the engine speed, but in this case, the disadvantage is that the control device is complicated and the cost increases significantly. There is.

The present invention has been made in view of the above circumstances, and by providing a plurality of resonance chambers with different volumes and selectively controlling the resonance chamber communicated with the intake passage in response to the engine speed. The present invention provides a simple and inexpensive noise reduction device that can sufficiently reduce intake noise over the entire rotation range even for internal combustion engines with a wide rotation range, such as automobile engines.

The present invention will be explained in detail below based on an illustrated embodiment.

In the figure, a plurality of resonance chambers 6a to 6c having different volumes are connected to an outside air introduction passage of an air cleaner 2 provided in an internal combustion engine 1 via a communication passage 4 and a rotary pulp 5.
By switching the rotary pulp 5, the resonance chamber communicating with the outside air introduction passage 3 can be switched and controlled.

Further, the engine 1 is equipped with a rotation sensor 7 that outputs a rotation speed signal (voltage) according to the rotation speed of the crankshaft, the knob, and the engine, and the output of the rotation sensor 7 is sent to a controller 8. By supplying the rotary pulp 5 to the rotary pulp 5, the rotary pulp 5 is selectively operated according to the engine speed. Reference numeral 9 denotes a motor that switches and operates the rotary pulp 5.

In the above configuration, when the engine 1 is operated, the intake pulsations are transmitted to the outside air introduction passage 3 as vibrations, so that the air in the resonance chamber is imaged via the communication passage 4 and the rotary pulp 5.

Now, considering the resonant frequency fN of the resonant chamber, the volume of the resonant chamber is v1, the length of the path from the outside air introduction passage to the resonant chamber is 21, the radius is r1, the constant is k, and it is given by: The damping effect is maximized when the pulsation frequency of the intake air and the resonance chamber frequency fN match.

Therefore, by switching the rotary pulp 5 according to the rotational speed of the engine 1 to change the resonance chamber communicating with the outside air introduction passage 3, intake noise can be reduced over the entire rotational range of the engine. It is needless to say in detail that the smaller the volume of the resonance chamber, the higher the resonance frequency, and the number of resonance chambers and the switching means are not limited to the embodiments.

As explained above, according to the present invention, the intake pulsation frequency (
The intake passage (
Since the volume of the resonance chamber that communicates with the external air intake passageway is changed by opening and closing a valve, it is possible to efficiently attenuate intake noise over the entire rotation range and reduce engine noise without complicating the entire system. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a diagram showing the attenuation characteristics of intake sound by each resonance chamber. 1... Internal combustion engine 8... Outside air introduction passage 4.
...Communication path 5...Rotary pal floor a~
6c... Resonance chamber 7... Rotation sensor 8... Controller 9... Motor patent applicant Hino Motors Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] A plurality of resonance chambers with different volumes are connected to each other in the engine's intake system through passages equipped with on-off valves, and
A noise reduction device for an internal combustion engine, comprising a controller that controls opening and closing of the on-off valve according to the engine speed to select a resonance chamber communicated with an intake system.