JPH06221239A - Variable type intake noise damper for car - Google Patents

Abstract

PURPOSE: To reduce noise to be generated from an engine intake system of a vehicle by providing a signal processing unit for detecting the engine speed, converting it into voltage and outputting it and a valve driving part for opening and closing a valve on the basis of a voltage signal from a comparing unit. CONSTITUTION: A vehicular variable intake noise damping device is provided with many valves 8a, 8b to be set in the specified positions in a side branch 6, and a signal processing unit 10 for adjusting the waveform obtained by detecting the engine speed and for outputting a signal converted from frequencies to voltage. A comparing unit 18 having many comparators 20a, 20b to be respectively connected to the valves 8a, 8b and for producing an opening and closing signal of the valve 8a by comparing the output signal of the signal processing unit 10 with a reference signal is provided. A valve driver 22a opens and closes the valve 8a through an actuator 24a on the basis of a signal output from the comparator 20a. Therefore, the length of the side branch 6 can be varied according to the engine speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle variable intake noise attenuator for reducing noise generated from an engine intake system of a vehicle.

[0002]

2. Description of the Related Art The noise of an engine mounted on a vehicle is classified into the engine itself, the exhaust system, and the intake system.

The noise due to the engine itself and the noise from the exhaust system can be solved by reducing the vibration of the engine body or utilizing the exhaust muffler. However, the noise from the intake system is fundamental unless a separate procedure is taken. It is difficult to solve.

The noise of the intake system is transmitted from the combustion chamber to the air cleaner via the intake manifold and is radiated to the outside when the intake valve is periodically opened and closed. This has a frequency component related to the number of revolutions of the engine, but the frequency component generally belongs to a low frequency region and causes vibration in the vehicle body to induce indoor noise.

The method of attenuating the noise of the intake system is a side branch type noise attenuator for reducing the noise by causing mutual interference of the acoustic waves by the principle of a so-called quarter wavelength filter, and a kinetic energy of the acoustic waves for resonance. There are two types, a cavity type noise attenuator that converts the energy into round trip energy and reduces noise.

The present invention relates to an improvement of the side branch type noise attenuator, of the two types mentioned above.

The basic structure of the side-branch intake noise attenuator will be described with reference to FIG.

In FIG. 5, the side branch B is connected to the intake passage A. When the intake noise propagates to the intake passage A, the side branch B resonates to generate a mutual interference wave, which interferes with the actual intake noise to eliminate the intake noise.

It has been reported that an engine having an intake noise attenuator has a slightly improved output and air-fuel ratio. The cause is that the efficiency of filling the air taken in the intake passage becomes high and the air is sucked into the cylinder. It is inferred that the amount of air taken is increased.

However, the problem with the above-described intake noise damping device is that the damping range of intake noise is narrow because the length of the side branch is fixed.

In other words, the frequency F of the intake noise to be attenuated is theoretically expressed by C / 4L. Here, C is the speed of sound, and L is the length of the side branch that functions as a resonance chamber. The effective frequency of this side branch determines the noise frequency to be attenuated. In order to solve the drawback of the existing intake silencer that the intake noise attenuation area is narrow, the intake noise attenuating device with a structure in which the end of the connection passage is installed inward so that it is not affected by intake air is released to Japan. It is disclosed in Japanese Patent Publication No. 88453, 1983. Further, a structure in which the inside of the resonance chamber is partitioned by a diaphragm, and a weight piece is attached to the center of the diaphragm to expand the resonance width with respect to variations in the engine speed is disclosed in Japanese Patent Laid-Open Publication No. 124057, 1983. There is. However, with such a structure, it is not possible to sufficiently cope with the fluctuation of the noise frequency due to the change of the engine speed.

[0012]

SUMMARY OF THE INVENTION In order to solve the above problems, an intake noise attenuating device having a structure capable of changing the volume of a resonance chamber by changing the engine speed is provided.
Published Japanese Patent Publication No. 70868, 1984, 1984, 1
No. 05958, Japanese Utility Model Publication 17 1983
2050, 1986 41813, 1987 188511
No. Further, a layout in which a large number of plates are laid out in a staggered manner inside the restricted resonance box to extend the length of the resonance passage is disclosed in Japanese Patent Laid-Open Publication No. 60, 1985.
No. 5,764.

The intake noise has a frequency component that changes depending on the engine speed, but from the viewpoint of noise reduction effect, it is preferable to change the length or volume of the resonance passage by changing the engine speed. However, this type of intake noise attenuator requires many parts and has a complicated structure.
In addition, since it must be installed by utilizing a small space existing in the engine compartment, if the device is larger than necessary and has a complicated shape, the assembly work becomes difficult.

Japanese Utility Model Bulletin 418, 1986
The variable intake noise attenuator disclosed in No. 15 presents a direction to solve the problem of the variable volume type described above.

In this system, the intake passage and the resonance box are connected by individual short conduits, and opening / closing valves are attached to the inlets of these conduits to selectively open / close each opening / closing valve according to the engine speed. It is a structure that opens and closes. This has a simple structure, but can effectively attenuate intake noise even when the engine speed changes.
However, since the intake noise attenuating device also has a large number of conduits arranged side by side, securing an installation space becomes a problem.

[0016]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a side-branch type intake noise attenuating device having a simple structure and a compact size, the volume of which can be varied depending on the engine speed. Is.

The above-described variable intake noise attenuator for a vehicle according to the present invention includes a number of valves installed at predetermined positions inside the side branch and a frequency / voltage by adjusting the waveform obtained by detecting the engine speed. A comparison unit that has a signal processing unit that outputs a converted signal and a plurality of comparators that are respectively connected to the plurality of valves, and that outputs an opening / closing signal of the corresponding valve by comparing the output signal of the signal processing unit with a reference signal. And a plurality of valve drivers respectively connected to the plurality of valves and a plurality of actuators for independently opening and closing the plurality of valves, and the corresponding valve driver outputs a signal from the corresponding comparator of the comparison unit. And a valve drive unit that opens and closes the corresponding valve through an actuator.

[0018]

In the present invention having the above-described structure, the valve arranged inside the side branch is a throttle valve or a butterfly valve, and the signal processing unit outputs the signal waveform detected by the rotation speed detection sensor. It consists of a signal processor for adjustment and a normal F / V converter for converting the frequency output from this signal processor into a voltage. Then, the comparison unit composed of a large number of comparators compares the constant reference voltage set in each comparator with the signal level output from the F / V converter, so that the engine speed range is low or medium. And determine what is one of the high speeds. When a signal is output from the F / V converter, the comparator to which the reference voltage higher than the signal level is set emits an output signal.

In the valve drive unit, a large number of actuators are constituted by ordinary solenoids having a push rod installed at the center thereof, and the push rod is connected to an arm fixed to one end of a support shaft of the valve. It is structured.

[0020]

The present invention will be described in detail below with reference to the following preferred embodiments and the accompanying drawings.

FIG. 1 illustrates a schematic structure of an intake noise attenuating apparatus related to the present invention.

A side branch 6 having a constant length L ₁ is installed in the middle of an intake passage 4 leading to the air cleaner 2, and a large number of valves 8 are provided inside the side branch 6.
a and 8b are arranged at predetermined positions.

In this embodiment, the valves 8 are arranged at two positions, but the side branch 6 has a constant length L ₁ and an intermediate length L ₂ by selectively opening and closing the valves 8a and 8b.
It can be changed to a short length L ₃ .

In the signal processing unit 10, the pulse output from the normal rotation speed detection sensor 12 for detecting the engine rotation speed is subjected to waveform adjustment by the signal processing unit 14, and then the engine rotation speed detected by the F / V converter 16 is detected. A voltage equivalent to the number will be output.

The output signal is applied to the comparison section 18.
The comparison unit 18 is composed of the same number of comparators 20a and 20b as the above-mentioned many valves 8a and 8b, but the reference voltage of a constant level set in each of the comparators 20a and 20b corresponds to the engine speed. Is used to segment the engine's rotational range.

In this embodiment, the reference voltage V _ref1 of the comparator 20a is set lower than the reference voltage V _ref2 of the other comparator 20b.

The output terminals of the comparators 20a and 20b are
The valve drivers 22a and 2 which constitute the valve drive unit 22.
2b is connected to each input terminal.

The valve drivers 22a and 22b are also installed in the same number as the valves 8a and 8b installed in the side branch 6 described above, and have a switch function of turning on by an output signal output from the connected comparators 20a and 20b.

The valve drivers 22a and 22b can use ordinary switching transistors and SCR elements.

A large number of actuators 24a and 24b are installed at the output ends of the valve drivers 22a and 22b.

The actuators 24a and 24b are also installed in the same number as the valves installed in the side branch 6.

FIG. 2 shows a connection structure between the actuators 24a and 24b and the valves 8a and 8b installed inside the side branch 6.

FIG. 2A shows a state in which the valves 8a and 8b are open.

The actuators 24a and 24b have a structure in which a push rod 26 is slidably installed at the center of the inside, and an exciting coil is wound around the push rod 26.

An elastic spring 30 is provided so as to cover the outer circumference of the push rod 26 which extends from the actuator 24a to the outside, and a spring seat 32 is provided.
Supported by. The free end of the push rod 26 is
It is linked to an arm 36 fixed to a shaft 34 that rotatably supports the valve 8a.

With such a structure, the push rod 2
6 rotates the arm 36 projecting to the outside by the force of the spring 30, and the valve 8a opens the passage of the side branch 6 as shown.

Of course, the turning angle of the valve 8a is limited to an angle range of 90 degrees by the stoppers 38 and 40 installed inside the side branch 6.

When the valve driver 22a is turned on in the above-mentioned open position of the valve 8a, the actuator 24a
While the exciting coil 28 is energized and excited, the push rod 2
6 is adsorbed as shown in FIG.

When the push rod 26 is attracted, the spring 30 compresses while storing repulsive energy, and the arm 36 interlocks to swivel the valve 8a to close the passage of the side branch 6.

When the attraction force of the exciting coil 28 disappears,
The push rod 26 is returned to the open position by the repulsive force of the spring, and the valve 8a is opened.

FIG. 3 is a flow chart for explaining a process in which the present invention having the above-mentioned structure operates according to the engine speed.

When the signal detected by the rotation speed detection sensor 12 and adjusted in waveform is input to the F / V converter 16, the F / V converter 16 converts the input frequency into a voltage and the comparison unit 1
The signal is output to 8.

In this process, the frequency and the voltage are proportional to each other. When the engine speed is low, the voltage is low, and when the frequency is high, the voltage is high.

Therefore, the reference voltage V of the comparator 20a is
_ref1 is lower than the voltage output from the F / V converter 16 in the medium speed region of the engine, and the reference voltage V of the comparator 20b
_{If ref2} is set higher than the voltage output from the F / V converter 16 in the engine low speed region, a signal is sent to the output terminals of all the comparators 20a and 20b in the engine low speed region, and all valves 8a and 8b are output. Will be opened and the side branch 6 will have a volume of constant length L ₁ . In the medium-speed region can also be opened by the valve 8a to secure the side branch 6 is intermediate the length L _2, the side branch 6 into the high region is closed all the valves are short length L ₃
With.

More specifically, in one example, the engine low speed range is set to 3,000 rpm (hereinafter referred to as "rp.
m. Hereinafter, the medium speed range is set to 3,000 r.p.m. p.
m. Above 4,000 r. p. m. Below, and the high-speed region is 4,000 r. p. m. In the above case, the comparator 2
The reference voltage V _{ref1 of} 0a is F /
It must be set lower than the voltage output from the V converter 16 and lower than the voltage output from the F / V converter 16 in the high speed region. In addition, the reference voltage V of the comparator 20b
_ref2 is higher than the voltage output from the F / V converter 16 in the low speed region, and F / V converter 16 in the medium speed region.
It must be set higher than the voltage output from.

When the reference voltage is set in this way, the comparators 20a and 20b of the comparison section 18 each independently generate a signal depending on whether the engine speed is in the low speed, medium speed, or high speed region, and the low speed is selected. All valves in the case of area 8
a and 8b are opened to make the side branch 6 have a volume of L ₁ length, and only the comparator 20a is operated in the medium speed region to make the side branch 6 have a volume of L ₂ length. comparator 20a, and outputs the signal from 20b and short length _{L 3} of the volume of the side branch 6.

FIG. 4 shows a 4-cylinder 4-cycle engine not equipped with an intake noise damping device, a 4-cylinder 4-cycle engine equipped with the conventional damping device illustrated in FIG. 5, and the side of the present invention. It is a comparison graph figure of the result which divided the noise which generate | occur | produces from each 4-cylinder 4-cycle engine equipped with the branch type intake noise attenuator into the 2nd noise at the distance of 1 m, and was measured.

As can be seen from this graph, the damping device of the present invention has an average noise damping effect over the entire engine speed region, and particularly has a good secondary noise damping effect.

[0049]

As described above, although the present invention has a simple structure, the length of the side branch can be changed depending on the engine speed, and the installation space can be reduced as compared with various conventional methods. Have an effect.

In particular, the side branch can be formed of a single cylindrical body, and if a flexible tube is used, the installation space can be further reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an intake noise damping device of the present invention.

FIG. 2 is a diagram illustrating an opening / closing operation of each valve in FIG.

FIG. 3 is a flowchart showing an operation sequence of the damping device of the present invention.

FIG. 4 is a graph comparing the performance of devices of the present invention.

FIG. 5 is a view showing an example of a conventional intake noise damping device. 6 side branch 8 valve 10 signal processor 12 rotation speed detection sensor 14 signal processor 16 F / V converter 18 comparator 20 comparator 22 valve driver 24 actuator 26 push rod 28 exciting coil 30 spring 36 ... arm 38. ..Stoppers

Claims (7)

[Claims] 1. A large number of valves installed at predetermined positions inside a side branch, a signal processing unit for adjusting a waveform obtained by detecting an engine speed and outputting a frequency / voltage converted signal, and A plurality of comparators connected to the respective valves, comparing the output signal of the signal processing unit with a reference signal and issuing an opening / closing signal of the corresponding valve, and a plurality of units respectively connected to the plurality of valves. A valve driver and a plurality of actuators that independently open and close the plurality of valves, and a corresponding valve driver that opens and closes the corresponding valve through an actuator according to a signal output from the corresponding comparator of the comparison unit. A variable intake noise attenuator for a vehicle, which is configured to include. 2. The noise damping device according to claim 1, wherein the valve inside the side branch is a throttle valve or a butterfly valve. 3. The signal processing unit, wherein the signal processor adjusts a signal waveform detected by a rotation speed detection sensor, and an F / F that converts a frequency output through the signal processor into a voltage.
The noise damping device according to claim 1, wherein the noise damping device comprises a V converter. 4. The noise attenuating device according to claim 1, wherein the reference voltages set to the plurality of comparators are divided and set according to numerical values corresponding to low, medium and high engine speed regions, respectively. 5. The noise damping device according to claim 1, wherein the valve driver is composed of a switching transistor or an SCR element. 6. A large number of actuators include a push rod slidably installed between an open position and a closed position, and an exciting coil wound around the push rod.
A spring installed on the push rod to return the push rod to the open position when the exciting coil is deenergized, and the free end of the push rod is connected to one end of the shaft that rotatably supports the valve inside the side branch. The noise damping device according to claim 1, further comprising an arm. 7. The noise damping device according to claim 1, wherein the side branch is formed of a flexible tube.