JPS61106931A - Intake noise reducing device - Google Patents

Abstract

PURPOSE:To reduce intake noise all over a running area by providing a throttle valve on an intake passage of Diesel engine and controlling the valve to a position always throttled by a predetermined amount according to intake pipe negative pressure. CONSTITUTION:A throttle valve 10 and a vacuum motor 16 are provided on an intake passage 4 of Diesel engine 2. A vacuum pump 38 is connected to a first negative pressure chamber 26 of the motor 16, and a vacuum modulator 44 is interposed in a passage 58 connecting a downstream portion of the throttle valve of the intake passage 4 and a passage 36. The throttle valve 10 is kept full opened at the starting, but the engine starts and the vacuum pump 38 actuates and negative pressure is supplied to the motor 16, then the valve opening is reduced. When the engine rotating number is increased, intake negative pressure is increased and a switch valve 50 is dissociated to reduce negative pressure of a negative pressure chamber and the opening of the valve 10 is increased, however when the air in the intake pipe becomes near to atmospheric pressure, the valve 50 is closed to close the throttle valve 10, and the throttle valve 10 is not made full opened.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake noise reduction device, and is particularly effective when used as a device for reducing intake noise of a diesel engine.

[Conventional technology]

In general, the load of a diesel engine is controlled, that is, the speed is controlled, by controlling the amount of fuel injection without controlling the amount of intake air. Therefore, like a gasoline engine, there is a throttle valve in the intake pipe that controls the amount of intake air.
Nor does it have anything equivalent. Therefore, there is a problem in that combustion noise in the combustion chamber flows back to the air cleaner side and becomes intake noise that can be heard from the air cleaner intake port.

Therefore, as shown in Japanese Unexamined Patent Publication No. 58-35241, an intake throttle valve has been provided in the middle of the intake pipe to reduce vibration and noise during no-load operation.

[Problem that the invention seeks to solve]

However, with this kind of engine, the intake throttle valve is in the fully open position when the engine is running under load, and the intake throttle valve is in the intermediate position when the engine is running under no load, so the intake noise is caused by the intake throttle valve. There is a problem in that sound insulation is only achieved during idling and deceleration.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to reduce intake noise in the entire rotation range of an engine.

[Means for solving problems]

In order to solve the above problems, the present invention takes the following measures. In other words, it has a valve body that is provided in the middle of the intake passage of a diesel engine and insulates combustion noise of the diesel engine by blocking this intake passage, and a first atmospheric chamber and a first negative pressure chamber, and a first atmospheric chamber and a first negative pressure chamber. ,,,
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75"t-Wb" A vacuum motor that operates the valve element by transmitting this displacement to the valve element, and a negative pressure source that generates negative pressure introduced into the first negative pressure chamber of the vacuum motor; A vacuum modulator having an on-off valve that regulates the amount of air flowing into the first negative pressure chamber, and a second diaphragm that is displaced by the differential pressure between the second atmospheric chamber and the second negative pressure chamber and supports the on-off valve. Negative pressure downstream of the valve body in the intake passage is introduced into the second negative pressure chamber, and when the negative pressure in the second negative pressure chamber increases, atmospheric air flows into the first negative pressure chamber. The intake noise reduction device is configured such that the opening amount of the valve element decreases when the amount of intake air increases and the negative pressure in the first negative pressure chamber increases.

〔Example〕

Next, an embodiment □ of the present invention will be explained based on FIG. FIG. 1 is a sectional view showing an embodiment. 2 in the figure is a diesel engine, and fresh 1° air is taken into the diesel engine 2'' combustion chamber (not shown) through an intake pipe 4. An air cleaner 6 is arranged at the tip of the intake pipe 4. The air cleaner 6 removes dirt, dust, etc. from the fresh air taken in through the intake port 8.A valve body 10 is disposed in the middle of the passage of the intake pipe 4 to open and close the passage. are the connecting member 12 and the connecting shaft 14
It is connected to the vacuum motor 16 via. The valve body 10 and the connecting member 12 rotate together around a shaft 18, and the free end of the connecting member 12 is connected to the connecting shaft 14.
are once connected by a connecting pin 20.

Next, the vacuum motor 16 will be described.

The external shape of this vacuum motor 16 is the first casing 22.
The interior thereof is divided by a first diaphragm 24 into a first negative pressure chamber 26 and a first atmospheric pressure chamber 28 .

The outer peripheral end of the first diaphragm 24 is held between the first casing 22 and the center thereof between two first holding plates 30. The other end of the connecting shaft 14 is fixed to the first holding plate 30, and a spacer is provided in the first negative pressure chamber 26 between the inner wall of the first casing 22 and the first holding plate 30. 1 spring 32 is arranged. The first spring 32 biases the first diaphragm 24 to the right in the figure, and the movement of the first diaphragm 24 is caused by the movement of the connecting shaft 14 and the connecting member 12.
is transmitted to the valve body 10 via. Atmospheric air is introduced into the first atmospheric chamber 28 through an atmospheric hole 34 formed in the first casing 22, and air is introduced into the first negative pressure chamber 26 from a vacuum pump 38 through a negative pressure passage 36. negative pressure is introduced.

The negative pressure passage 36 branches in the middle, and the branch passage 40
is in communication with the second atmospheric chamber 42 of the vacuum modulator 44 . The outer shape of the vacuum modulator 44 is formed by a second casing 46, and the interior thereof is divided by a second diaphragm 47 into the second atmospheric chamber 42 and a second negative chamber 48. The branch passage 40 is connected to the second
An on-off valve 50 is disposed at a position that protrudes into the atmospheric chamber 42 and faces the protruding end of the branch passage 40 .

This on-off valve 50 is fixed to the second diaphragm 47, and the second diaphragm 47 is held between a second holding plate 52 and a second holding plate 52. Further, a second spring 54 is disposed in the second negative pressure chamber 48 between the second presser plate 52 and the inner wall of the second casing 46, and the on-off valve 50 and the second diaphragm 47 are connected to the on-off valve 50. is biasing the branch passage 40 in the direction of closing. Further, the second atmospheric chamber 42 communicates with the atmosphere via an air filter 56, and the second negative pressure chamber 48 is connected to the engine 2 side (downstream side) from the valve body 10 via a communication passage 58. Negative pressure inside the intake pipe 4 is introduced. Note that the negative pressure passage 36 is provided with a throttle 60 closer to the vacuum pump 38 than the branch point with the branch passage 40 .

Next, the operation of the above embodiment will be described. Before the engine 2 is started, the vacuum pump 38 is not operating, and the first diaphragm 24 is moved toward the atmospheric chamber 28 by the biasing force of the first spring 32. The amount of movement of the first diaphragm 24 is transmitted to the valve body 10 via the connecting shaft 14 and the connecting member 12, and the valve body 10 fully opens the intake passage 4. At this time, the second diaphragm 47 receives the biasing force of the second spring 54 and closes the atmospheric chamber 42.
The opening/closing valve 50 contacts the protruding end of the branch passage 40 and closes the branch passage 40.

When the engine 2 is started, the vacuum pump 38 also begins to operate, and the negative pressure generated by the vacuum pump 38 is introduced into the first negative pressure chamber 26 of the vacuum motor 16 through the negative pressure passage 36.

Then, the first diaphragm 24 receives this negative pressure, and the first diaphragm 24 receives the negative pressure.
The first diaphragm 24 resists the biasing force of the spring 32.
moves to the first negative pressure chamber 26 side. The amount of movement of the first diaphragm 24 is then transmitted to the valve body 10, and the valve body 10 rotates around the shaft 18 to close the suction pipe 4. Then, the negative pressure inside the intake pipe 4 on the downstream side of the valve body 10 increases,
This increased negative pressure is introduced into the second negative pressure chamber 48 via the communication path 58. Then, the second diaphragm 47 moves toward the second negative pressure chamber 48 against the urging force of the second spring 54, and the on-off valve 50 opens the branch passage 40 to the second atmospheric chamber 42. Then, the atmosphere that had been introduced into the second atmospheric chamber 42 through the air filter 56 is guided into the first negative pressure chamber 26 through the branch passage 40 and the negative pressure passage 36, and The negative pressure inside is diluted by the atmosphere. and,
The first diaphragm 24 moves toward the first atmospheric chamber 28, and eventually the first diaphragm 24 reaches a position where the force received by the first diaphragm 24 due to the negative pressure in the first negative pressure chamber 26 and the biasing force of the first spring 32 are balanced. 1 diaphragm 24 stops, valve body 10
It also maintains its opening.

In this way, the opening amount of the valve body 10 is determined. When the engine 2 is running at low speed, the negative pressure generated in the intake pipe 4 is small, and the negative pressure led to the second negative pressure chamber 48 is Since the pressure is also low, the branch passage 40 is closed by the on-off valve 50.

Therefore, vacuum.

All of the negative pressure from the pump 38 is introduced into the first negative pressure chamber 26 □, the first diaphragm 24 moves toward the first royal chamber 26, and the opening amount of the valve body 10 is reduced.

On the other hand, when the engine 2 rotates at a high speed, the negative pressure in the intake pipe 4 increases, and the on-off valve 50 separates from the protruding end of the branch passage 40. As a result, the negative pressure in the first negative pressure chamber 26 is diluted by the atmosphere, the first diaphragm 24 moves toward the atmospheric chamber 28, and the valve body 10 increases its opening amount. Here, valve body 1
0 fully opens the intake pipe 4, the pressure inside the intake pipe 4 becomes almost equal to atmospheric pressure, so the on-off valve 50 opens the branch passage 4.
0 is closed, and all the negative pressure from the vacuum pump 38 is guided to the first negative pressure chamber 26. Therefore, since the valve body 10 reduces its opening degree, the valve body 10 is never fully opened. In other words, the valve body 10 always has a constant inclination angle with respect to the intake pipe 4 and reduces the passage area of the intake pipe 4, so that it always has a sound insulation effect against combustion noise. FIG. 5 shows the results of an experiment comparing the noise levels of this embodiment and the conventional example.

FIG. 6 is a sectional view of essential parts showing a second embodiment of the present invention. In the embodiment described above, the valve body 10 and the vacuum motor 16
was installed in the intake pipe 4, but in this embodiment, the air cleaner 6
A valve body 10 and a vacuum motor 16 were attached to a nose portion 8a forming an intake port 8. The atmospheric hole 34 opening into the first atmospheric chamber 28 matches the communication hole 8b formed in the nose portion 8a, and the atmosphere within the nose portion a is guided into the first atmospheric chamber within two days. Other configurations and operations are similar to those of the previous embodiment.

3 and 4 are diagrams showing a third embodiment of the present invention, with FIG. 3 being a plan view and FIG. 4 being a longitudinal sectional view. The air cleaner 6 shown in this embodiment is called a body-mounted air cleaner, and impurities are removed from the air that flows in from the intake port 8 while swirling in the air cleaner. Therefore, normally something called a cyclone vane is provided to generate this swirling flow, but in this embodiment, the valve body 10 is disposed within the nose portion a forming the intake port 8,
This valve body 10 also plays the role of a cyclone blade.

Other configurations and operations are similar to those of the previous embodiment. Note that the arrows in FIGS. 3 and 4 indicate the flow of intake air.

〔Effect of the invention〕

i: As explained above, if the intake noise reduction device of the present invention is used, the valve body is located in the intake passage and always insulates engine combustion noise, so the intake noise is reduced throughout the entire rotation range of the engine. can be prevented from occurring. The sound insulation effect is particularly great in the low engine speed range.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the first embodiment, Fig. 2 is a sectional view of main parts of the second embodiment, Fig. 3 is a plan view of the third embodiment, and Fig. 4 is a sectional view of the third embodiment.
FIG. 5, a longitudinal sectional view of the embodiment, is a diagram showing the effects of the first embodiment. 2...Diesel engine, 10...Valve body, 16.
...Vacuum morph, 24...first diaphragm,
26...1st negative pressure chamber, 2nd...1st atmospheric chamber, 38.
...Vacuum pump (negative pressure source), 42...Second atmospheric chamber, 44...Vacuum modulator, 47...Second diaphragm, 48...Second negative pressure chamber. Acting Patent Attorney Takashi Okabe

Claims (1)

[Scope of Claims] A valve body that is provided in the middle of an intake passage of a diesel engine and insulates combustion noise of the diesel engine by blocking the intake passage, and a first atmospheric chamber and a first negative pressure chamber, A vacuum motor has a first diaphragm that is displaced by a pressure difference between the two chambers, and transmits this displacement to the valve body to operate the valve body; and a vacuum motor that is introduced into the first negative pressure chamber of the vacuum motor. It has a negative pressure source that generates pressure, and an on-off valve that adjusts the amount of air flowing into the first negative pressure chamber, and is displaced by the differential pressure between the second atmospheric chamber and the second negative pressure chamber, and the on-off valve a vacuum modulator having a second diaphragm that supports; negative pressure downstream of the valve body in the intake passage is introduced into the second negative pressure chamber, and when the negative pressure in the second negative pressure chamber increases; An intake noise reduction device configured such that when the amount of atmospheric air flowing into the first negative pressure chamber increases and the negative pressure in the first negative pressure chamber increases, the opening amount of the valve body decreases.