JPS59168215A - Resonator - Google Patents

Abstract

PURPOSE:To provide a resonator used effectively as a means for reducing noises of intake air or exhaust gas in an internal combustion engine, which is capable of obtaining a high resonance effect over a wide frequency range, by providing a plurality of resonance chambers the volume of which is decreased gradually, and placing a resonance chamber having a smaller volume in a resonance chamber having a larger volume successively. CONSTITUTION:In case of using a resonator of this invention as a means for reducing noises of intake air, one end of an outer tubular member 151 of a double tubular member 15 is connected to an intermediate portion of an intake duct 13 which is connected to an intake pipe 12. The other end of the outer tubular member 151 is connected to a first housing 40 constituting a first resonance chamber 17a, there is provided a second housing 41 which has a common bottom face with the first housing 40 and has an opening formed coaxially with the opening of the first housing 40. The second housing 41 constitutes a second resonance chamber 17b. Here, arrangement is such that the resonance frequency of the resonator is changed by sliding an inner tubular member 152 on the inside of the outer tubular member 151.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resonator that changes the resonant frequency of a pipe when air passes through the pipe, and is used, for example, as a device for reducing intake or exhaust noise of an internal combustion engine (1). It is valid.

When a conventional resonator is used as an intake noise reduction device for an internal combustion engine, the resonator 18 is installed in the middle of the intake duct 13 as shown in FIG. Tubular member 15 communicating with 14 and resonance chamber 1
Consists of 7.

The resonant frequency fp of this resonator 18 is fp-(C/21
JS/ (V - p p -... - (11 (however, fp - β + 0.8D, S - πD 2/4). Here, S is the opening cross-sectional area of the tubular member 15, D is the inner diameter of the tubular member 15, l is the length of the tubular member 15, and ■ is the internal volume of the resonance chamber 17. Therefore, in the conventional resonator,
The resonant frequency fp is determined by the structure, and a damping effect can only be obtained at that specific single resonant frequency rp, which poses a problem in that it does not work effectively against noise whose frequency characteristics change from moment to moment.

Therefore, in view of the above problems, the present invention aims to provide a resonator that can resonate a plurality of frequencies.

In order to achieve this objective, the present invention provides a plurality of resonance chambers whose volumes gradually decrease (2), and among the plurality of resonance chambers, resonance chambers with a small volume are sequentially housed in a resonance chamber with a large volume. Any one of the resonance chambers was configured to communicate with the air flow passage through a tubular member.

Embodiments in which the present invention is used as an intake noise reduction device for an internal combustion engine will be described below with reference to the drawings.

As shown in FIG. 2, the upper part of a cylinder 1 in which a piston 2 is slidably fitted is covered with a cylinder head 3, and the cylinder head 3 has an intake port that is periodically opened and closed by an intake valve 4 and an exhaust valve 5. 6, and an exhaust lower. The exhaust lower communicates with an exhaust pipe 30 via an exhaust passage 8, and the exhaust pipe 30 is provided with a muffler (not shown) for muffling exhaust noise.

On the other hand, the intake port 6 is connected to the intake passage 9 and the opening and closing port 10 (
In the case of a diesel vehicle, it is connected via a carburetor 1o to an air cleaner 11 that purifies intake air. A suction pipe 1 is provided at the upstream end of the air cleaner 11.
2 is attached, and the tip of the suction (3) pipe 12 is connected to an intake duct 13 made of resin, and the tip opening 13a of the intake duct 13 is open to the atmosphere.

The tubular member 15 is an outer tubular member 1 made of polypropylene resin.
51 and an inner tubular member 152, one end of the outer tubular member 151 is attached to the intake duct 13 with adhesive.
It is fixed by means such as screwing, caulking, welding, etc., and the other end is fixed by means such as adhesive, screwing, caulking, welding, etc. to the first housing 40 made of polypropylene resin that forms the first resonance chamber 17a. As a result, the air flow passage 14 in the intake duct 13 and the first resonance chamber 17a formed by the first housing 40 are communicated with each other. On the other hand, the inner tubular member 152 is fitted into the outer tubular member 151 so as to be able to slide therein, and the ends of the 13 intake ducts are fixed to the outside of the intake duct 13. It is connected to a linear actuator 20 via a shaft 19.

A second housing 41 is installed in the first resonance chamber 17a, which shares its bottom surface with the first housing and whose opening is coaxial with the opening (4) of the first housing. A second resonance chamber 17b is formed by this second housing 41, and the inner tubular member 1
52 slides within the side tubular member 151, the airflow passage 14 and the second resonance chamber 17b are communicated with each other.

The linear actuator 20 uses, for example, a step motor that can electrically easily and accurately control the position in the axial direction. Control computer 2 that detects the engine speed and outputs accordingly
The linear actuator 20 receives a drive signal from the linear actuator 1 and moves the inner tubular member 16 fixed to the shaft 19 up and down according to the rotational speed of the engine using the inner wall of the outer tubular member 15 as a guide. The control computer 21 receives a rotation signal from, for example, a distributor (not shown) or a crank pulley (not shown), reads the engine rotation speed, and determines a resonance frequency corresponding to the dominant frequency component of the intake noise at that time. A driving signal is sent to the linear actuator 20 so as to obtain the linear actuator (5). A flowchart showing the control method of this control computer 21 is shown in FIG.

FIG. 4 is a perspective view of the inner tubular member 152. As can be seen from FIG. 4, a plurality of beams 152a are provided inside the end of the inner tubular member 152.
A fixing hole 152b is provided in 2a. The shaft 19 is fixed in this fixing hole 152b by screwing, caulking, etc., and the inner tubular member 152 and the linear actuator 20 are connected. Furthermore, the inner tubular member 1
The outer wall of the outer tubular member 15 is in contact with the inner wall of the outer tubular member 15 to prevent air leakage, and has dimensions that allow vertical sliding movement.

Next, the operation of the embodiment described above will be explained.

For example, the control computer 21 reads the engine rotation speed from a rotation signal from a distributor (not shown) or a crank pulley (not shown), and according to this engine rotation speed (6) linearly outputs a preset disturbance signal. to the actuator 20. The linear actuator 20 that receives the disturbance signal slides the inner tubular member 152 within the outer tubular member 151 via the shaft 19 in response to the disturbance signal.

When the inner tubular member 152 is completely contained within the outer tubular member 151 as shown in FIG. 5, the resonant frequency f =
f L OW is the length e=β0 of the tubular member 15 and (20:
the length of the outer tubular member 151), the inner diameter of the inner tubular member 152, and the effective chamber volume V of the first resonance chamber 172 obtained by removing the volume of the second housing 41 from the volume of the first housing 40.
=Vo. In other words, the resonance frequency f=f and □w is f L OW= (C/2π) S/(Vo=i2
p) (7!1)=j! o+0.8D, S-πD 2
/ 4) ...---(2+) Then, the inner tubular member 152 slides inside the outer tubular member 151,
As it gradually protrudes toward the second resonance chamber 17b, the resonance frequency f also gradually changes. Resonant frequency f = fm at that time
is (7) fm-(C/2 π) 1 7 z ■] te 1 completed (7!p
= 7!0 +I! m + 0.8 D, S =
tt D 2/ 4 )...(3). However, Ilm is the length by which the inner tubular member 152 protrudes from the outer tubular member 151.

Thereafter, as shown in FIG. 6, when the inner tubular member 152 slides within the outer tubular member 151 and connects with the second housing 4I, and only the airflow passage 14 and the second resonance chamber 17b communicate with each other, the resonance frequency f =fup is the length β-7 of the tubular member 15! o+β1 (7! + i variable amount of the linear actuator 20) and the chamber volume of the second resonance chamber 17b V−V +
and the inner diameter of the inner tubular member 152, fup=(C/2π) S/(vl-7!p)(ρp=
7!0-1-21 +0.8D, S=πD2/4)...
...(4) becomes.

The relationship between the length ρ of the tubular member 15 and the resonance frequency f is as shown in FIG.

Next, let's find the specific resonance frequency.

(8) For example, the length ffo of the outer tubular member 151 is 30 m, the inner diameter D of the inner tubular member 152 is 20 m, and the first resonance chamber 17a
Effective chamber volume Vo=1000cc, second resonance chamber 17b
If the chamber volume V+ = 544 cc and the actuator variable amount β+ = 20 m, then the lower limit resonance frequency rL
OW is 141 Hz, upper limit resonance frequency fup is 160H
It becomes z. By sliding the inner tubular member 152 using the linear actuator 20 in this manner, the resonance frequency can be switched between 141H2 and 160Hz.

Further, by appropriately selecting the shape and dimensions of the resonator 18 for the variable amount 7!1 of the same linear actuator 20, the two resonance frequencies can be set to desired values.

FIG. 8 shows the relationship between engine speed and intake noise level. The thin line (A) in FIG. 8 shows the relationship when no resonator is installed, and it can be seen that there is a large noise peak around 4000 to 4800 rotations. This noise peak is the second-order component of the engine speed, that is, 1
33Hz to (9) 160Hz are dominant. Therefore, by setting the resonant frequency of the resonator 18 of this embodiment to 145T(z,'160H2) and synchronously varying the engine speeds at 4,350 and 4,800 revolutions, the As shown in Figure 8, the intake noise can be significantly reduced compared to the conventional resonator installation (dotted chain line (b) in Figure 8).

Next, other embodiments of the present invention will be described.

FIG. 9 shows a second embodiment, which takes into consideration the ease of mounting the resonator 18. That is, in the first embodiment, the resonator 18 was directly fixed to the intake duct 13, but in this embodiment, the resonator 18 and the linear actuator 20 are installed in the mounting pipe 131, and this mounting pipe is attached to any part of the intake duct 13. Connect to the part. In this way, the mounting position of the resonator can be freely changed during the day. Other configurations and effects are similar to those of the first embodiment.

FIG. 10 shows a third embodiment. In the first embodiment, the linear actuator 20 was fixed to the intake duct 13, but in this embodiment, the linear actuator (10) 20 was attached to the first housing 40. . In other words,
A linear actuator 20 was attached to the wall of the first housing 40 on the opposite side of the tubular member 15, and the end of the inner tubular member 152 on the first resonance chamber 17a side and the linear actuator 20 were connected by a shaft 19. In this way, only one hole for attaching the outer tubular member 152 needs to be provided in the intake duct, so that the assembly time can be shortened.

FIG. 11 shows a fourth embodiment, in which the resonance chamber and the tubular member 15 have a triple structure, and there are three resonance chambers 17a, 17b,
17c are communicated with the air flow passage 14.

By doing this, three resonant frequencies can be obtained. It goes without saying that three or more resonance chambers may be provided.

Although the present invention was used to reduce intake noise in the above embodiments, it is also effective to install the present invention in an exhaust duct and use it as an exhaust noise reduction device.

In addition, conventionally, if the natural resonance frequency of the intake passage pipe for intake air in the intake system and the opening/closing frequency of the intake valve are made to match, it is easy to draw a large amount of mixed gas (fuel and intake air) into the cylinder. This is known in the art, and the length of the intake pipe is selected so as to obtain resonance at the rotational speed of the internal combustion engine, thereby increasing the engine output at that rotational speed. By installing the resonator of the present invention in the middle of the suction pipe and making its resonant frequency variable, the natural resonance frequency of the entire suction pipe can be changed, and the opening/closing timing of the suction valve can be changed. By synchronizing, it can also be implemented as a means for increasing the output in a desired rotation range of the internal combustion engine.

As described above, by using the resonator of the present invention, a plurality of arbitrary resonance frequencies can be obtained, and a resonance effect can be obtained in a wide frequency range.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing a conventional resonator, and Figures 2 to 7 are sectional views of a conventional resonator.
2 is a sectional view, FIG. 3 is a flowchart, FIG. 4 is a perspective view of the inner tubular member, FIGS. 5 and 6 are sectional views showing the operation, and FIG. 7 is the tubular member. Figure 8 is a diagram showing the relationship between engine speed and noise level, Figure 9 is a sectional view showing the second embodiment, and Figure 10 is the third embodiment. Cross section, 11th
The figure is a sectional view showing the fourth embodiment. I4... Air flow path, 15... Tubular member, 151.
...Outer tubular member, 152...Inner tubular member, 17a
...first resonance chamber, 17b...second resonance chamber. Representative Patent Attorney Takashi Okabe (13) Figure 3 Figure 4 Figure 5 Figure 6 Key, S Figure 11 Previous (1. Name of the invention Resonator 3 Relationship with the person making the amendment Patent applicant 1-1 Showa-cho, Kariya City, Aichi Prefecture (426) Representative of Nippondenso Co., Ltd. Toda Sodai 4th generation Mr. Masato 〒448 1-1-5 Showa-cho, Kariya City, Aichi Prefecture Plans subject to correction

Claims (1)

[Claims] In a resonator that changes the resonant frequency of an airflow passage,
The plurality of resonance chambers are provided with a plurality of resonance chambers whose volume gradually decreases, and a tubular member that communicates the plurality of resonance chambers with the air flow passage. the chamber is gradually accommodated with its opening coaxially arranged, the tubular member comprising an outer tubular member and an inner tubular member;
The outer tubular member connects and fixes the air flow passage to the resonance chamber having the largest volume, and the inner tubular member slides inside the outer tubular member to communicate any one of the plurality of resonance chambers with the air flow passage. A resonator characterized by: