JPS6022021A - Variable resonator - Google Patents

Abstract

PURPOSE:To lower the noise level of an engine effectively, by connecting resonance chambers to an air intake passage via a plurality of members in the form of communicating pipes, communicating the resonance chambers with each other via a connecting pipe having therein an ON-OFF valve, and controlling operation of the ON-OFF valve according to the engine speed. CONSTITUTION:In an engine, in which an intake duct 13 is connected to an air cleaner 11 connected on the upstream side of a carburetor 10 via an air intake pipe 12 and the opening 13a at the top of the intake duct 13 is opened to the atmosphere, a first and a second members 15, 16 in the form of communicating pipes are connected to intermediate portion of the intake pipe 12 or the intake duct 13 separately from each other. The other ends of the tubular members 15, 16 are opened respectively in a first and a second resonance chambers 17, 18 consisting of enclosed spaces, and the two resonance chambers 17, 18 are communicated with each other via a connecting pipe 19. Further, an ON-OFF valve 21 is disposed in the connecting pipe 19, and operation of the ON-OFF valve 21 is controlled by a micro-computor 23 by the aid of an actuator 22 such that the resonant frequency equal to the dominant frequency component of the intake noise varied with the engine speed can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resonator whose resonance frequency can be varied in synchronization with the rotational speed of an internal combustion engine.

A conventional resonator was constructed as shown in FIG.

That is, the conventional resonator 17 is installed in the middle of the intake duct 13 and is composed of a communicating tubular member 15 that communicates with the inner suction passage 14 of the intake duct 13, and a resonance chamber 16 in which the end surface of the communicating annular member 15 is open. It had been. The resonant frequency fP of this resonator 17 is fp=c/2πJy7T7
Ding Ding... (1). (S−πD2/4.β
p=#-1-Q, 3D) Here, S is the communicating tubular member 15
, D is the inner diameter of the communicating annular member 15 , l is the length of the communicating tubular member 15 , and ■ is the internal volume of the resonance chamber 16 .

Therefore, in the conventional resonator, due to its structure, the resonant frequency f
P was fixed uniformly, and a damping effect could only be obtained at that specific resonance frequency rp.

Therefore, when installed in the intake duct of an internal combustion engine where the resonant frequency changes from moment to moment, a sufficient damping effect could not be obtained.

In view of the above problems, the present invention aims to make the resonant frequency variable and expand the controllable frequency range.

In order to achieve this objective, in the present invention, a plurality of resonance chambers are provided, and the resonance chambers are communicated with each other through a connecting pipe. and,
The passageway of this connecting pipe was opened and closed by an on-off valve, and the resonant frequency was varied by making the plurality of resonance chambers act independently or by integrating them through the connecting pipe.

Hereinafter, an embodiment in which the present invention is used as an intake noise muffling device in an internal combustion engine intake system will be described with reference to FIG.

In Fig. 2, 1 is a cylinder in which a piston 2 is slidably fitted, the upper part of which is covered with a cylinder head 3, and an intake valve 4 and an exhaust valve 5 are periodically connected to the cylinder head 3. An intake port 6 and an exhaust lower are formed to be opened and closed.

The exhaust lower communicates with the exhaust pipe via the exhaust passage 8,
This exhaust pipe is provided with a muffler (not shown) for muffling exhaust noise.

On the other hand, the intake port 6 is connected to an intake passage 9 and a carburetor reflex 10 (
In the case of a diesel vehicle, the carburetor 10 is not present) and is connected to an air cleaner 11 that purifies intake air. A suction pipe 12 is attached to the upstream end of the air cleaner 11, and a suction duct 13 is connected to the tip of the suction pipe 12.
11 opening 13a is open to the atmosphere.

In the middle of this intake pipe 12 or intake duct l-13 (intake duct 13 in this embodiment), there is a first receiving tubular member 15.
and the second communicating tubular member 16 is branched. One end of the first and second communicating tubular members 15 and 16 communicates with the suction passage 14 in the intake duct 13, and the other end opens into a first resonance chamber 17 and a second resonance chamber 18, each of which is a closed space. The first resonance chamber 17 and the first communicating tubular member 15 form a first resonator A.
However, the second resonator B is formed by the second resonance chamber 18 and the second communicating tubular member 16. The first resonance chamber 17 and the second resonance chamber 18 communicate with each other through a connecting pipe 19. An on-off valve 21 for opening and closing communication of the connecting pipe 19 is installed inside the connecting pipe 19.

This opening/closing valve 21 is plate-shaped, and is rotated so as to be perpendicular to the flow direction of the connecting pipe 19 to close the connection 919, and rotated so as to be parallel to the flow direction to open the connecting pipe 19. In addition, the 1.2 resonators A and B
Since the intake duct 13 is a resin blow-molded product, the intake duct 13 and the first and second resonators A and B are fixed by appropriate means such as adhesive, screwing, tightening, welding, etc.

In addition, the control computer 23 calculates a resonance frequency in synchronization with the engine rotation based on a rotation signal from a rotation detector (not shown) of the internal combustion engine, and an electric signal based on the calculation is applied to the actuator 22. It has become. Therefore, the on-off valve 21 , which is fixed to the shaft 24 of the actuator 22 by screwing, tightening, etc., opens and closes the connecting pipe 19 in response to electrical signals from the computer 20 .

Next, a method of controlling resonance frequency switching in synchronization with the rotational speed of the internal combustion engine will be described. As shown in Figure 1, the rotation signal of the internal combustion engine (
A control computer 23 using a microcomputer (not shown) reads the engine rotation speed, and sends a drive signal to the actuator 22 so as to obtain a resonance frequency that matches the dominant frequency component of the intake noise at each rotation. 19 to change the resonance frequency.

A flowchart showing the above-mentioned control method is shown in FIG. 5, and the actuator 22 is rotated forward and reverse even when the rotational speed of the internal combustion engine increases or decreases, so that the resonant frequency can always be switched in synchronization with the rotational speed. It is possible to make a=. Further, since the resonator of the present invention performs ON-OFF control of the actuator with respect to the engine speed, there is an advantage that the capacity of the control controller 23 can be small.

Now, as shown in FIG. 3, when the on-off valve 19 is closed, the first resonator A consisting of the first resonance chamber 17 and the first receiving tubular member 15, the second resonance chamber 18 and the second A second resonator B consisting of a communicating tubular member 16 is formed, and the resonant frequency f of the first resonator A is
P'l is f P I -A π D+'/4V1(n
Ivy + Q, 8 D + ) (A=C/2π) The resonant frequency fP2 of the second resonator B is (A='C/2π).

Next, the on-off valve 19 linked to the actuator 22 is
By rotating, the resonance chamber 17 and the resonance chamber 18 communicate with each other as shown in FIG. 4 -1-, and a composite resonator of the first resonator A and the second resonator B is established. The resonance frequency fP3 is fp3=A TtD32/V'3 (β3-1-0.8
D3) (A=C/2 π, v3=vl+v2, D3-J
``τ'' ``T interpretation p3-βIII2).

Next, a specific resonance frequency is calculated. For example, the first
Resonance chamber A volume V+=1000cc, first communicating tubular member 1
5 opening diameter D + = 25 am, first communicating tubular member 1
5 length β+ = 40 n+n, second resonance chamber B volume V 2
= 800 cc, second communicating tubular part month 16 open diameter D
2=20+lIN, second communicating tubular member 16 length 12=
When set to 40 fins, when the on-off valve 21 is closed,
At the same time f p + = 155 Hz, f p 2
Two resonant frequencies of = 14.3 Hz are obtained, and when the on-off valve 21 is open, the resonant frequency is 141 Hz. By rotating the on-off valve 21, the resonance frequency can be increased to 14
1Hz and 143 I-1z or 155 II z
can be switched to

FIG. 6 shows the effect of applying the present invention to internal combustion engine intake noise reduction. The thin line in the figure is the intake noise when no resonator is installed.
There is a loud noise peak around 000 to 4800 rpm, which is a problem. This noise peak is dominated by the second-order component of the engine speed, that is, from 133 Hz to 160 Hz.

Therefore, the resonant frequency of the resonator of the present invention is set to 141 Hz.
, 14'3Hz, 155Hz, engine speed 4
By switching at 650 rotations, the intake noise can be significantly reduced compared to the conventional resonator installation (dotted chain line), as shown by the thick line in the figure.

Note that the 1.2 resonators A and B of this example can also provide the following effects.

In other words, if the natural resonance frequency of the intake passage pipe for intake air with the intake diameter matches the opening/closing frequency of the intake valve, a large amount of mixed gas (
It is well known that the internal combustion engine (fuel and intake air) is drawn into the cylinder.For this reason, in the past, the length of the intake pipe was selected to obtain resonance at a certain rotational speed of the internal combustion engine, and the engine output at that rotational speed was is increasing.

Therefore, by installing the 1.2 resonators A and B in the middle of the suction pipe and making the resonant frequency variable, the natural resonance frequency of the entire suction pipe can be changed, and the opening/closing timing of the suction valve 4 can be changed. - If synchronized with engine timing, it can also act as a means to increase the output in the entire rotation range of the internal combustion engine.

Although the above-mentioned examples are desirable embodiments of the present invention, the present invention has various embodiments in addition to the above-mentioned examples.

That is, as shown in FIG. 7, considering the ease of mounting the 1.2 resonators A and B, the resonator mounting portion 13' can be separated from the intake duct 13 and the mounting position can be changed freely. It is also possible to do so.

In addition, in the above embodiment, the first and second resonators A and B were installed in the intake system and used as a method for reducing intake noise, but resonators with the same configuration were installed in the exhaust system to reduce exhaust noise. Similar effects can be obtained even when implemented as a device.

Further, although two resonance chambers were provided in the above-mentioned embodiment, the number is not limited to two, and if three or more are provided, a wider range of resonance frequencies can be obtained.

As explained above, by using the variable resonator of the present invention, it is possible to obtain multiple resonant frequencies and expand the controllable frequency range, thereby reducing the noise level more than with conventional ones. be able to.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional resonator, FIG. 2 is a sectional view showing the J embodiment of the present invention, FIGS. 3 and 4 are sectional views for explaining the operation, and FIG. 5 is a sectional view showing a conventional resonator. 2 is a flowchart showing the operation of the control computer of the apparatus, FIG. 6 is a diagram showing the effect, and FIG. 7 is a sectional view showing a second embodiment of the present invention. 15... First communicating tubular member, 16... Second communicating bamboo member, 17... First resonance chamber, 18... Second resonance chamber,
19... Connecting pipe, 21... Opening/closing valve, 22... Actuator, 23... Control computer. Representative Patent Attorney Takashi Okabe Figure 3] J Figure 4 Figure 5

Claims (1)

[Claims] A plurality of communicating tubular members each having one opening opening into a passage leading to a cylinder of an internal combustion engine, and each of the communicating tubular members Di!
A resonance chamber consisting of a closed space communicating with J, a connecting pipe that communicates each of these resonance chambers with each other, an on-off valve that opens and closes the passage of this connecting pipe, and an on-off valve that opens and closes the on-off valve based on an electric signal. A variable resonator comprising an actuator and a control computer that detects the rotational speed of the internal combustion engine and controls an electrical signal output to the actuator.