JPS6291634A - Intake noise reduction device for engine - Google Patents

Abstract

PURPOSE:To reduce intake noise by restricting an intake passage as much as possible in a low engine speed range where the output of an engine is not decreased even if the intake passage is restricted because the intake passage is sufficiently large in cross sectional area. CONSTITUTION:When an engine 1 is started, a vacuum pump 9 is operated, and as negative pressure is inducted into a vacuum motor 10 through a passage 8, a valve disc 6 is allowed to close an air intake duct 2. In this case, when an engine 1 runs at a low speed, exhaust pressure from an exhaust air duct 3 which is inducted into a pressure chamber 25 of a negative pressure control valve 20 through a passage 30, is small. Accordingly, a branch passage 18 is closed by a closing valve 27, then negative pressure from the above said pump 9 is entirely inducted into No.1 negative pressure chamber 13 of the above said motor 10 allowing the valve opening of the valve disc 6 to be decreased so as to enable combustion noise to be reduced. On the other hand, when the engine 1 speed is increased, exhaust pressure is increased, and as the closing valve 27 is allowed to open the branch passage 18, the valve opening of the valve disc 6 is increased so as to reduce the loss is pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an intake noise reduction device effective for reducing intake noise of a diesel engine.

[Conventional technology]

Generally, 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, unlike a gasoline engine, the engine does not have a throttle valve in the middle of the intake pipe for controlling the amount of intake air, and there is no equivalent device.

Therefore, there is a problem in that combustion noise in the combustion chamber flows back through the intake passage and the air cleaner, becomes intake noise, and is released into the atmosphere from the air cleaner intake port.

Therefore, as shown in Japanese Unexamined Patent Application Publication No. 58-35241, there has been a conventional engine in which an intake throttle valve is 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 type 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 with no load, so the intake noise is reduced by the intake throttle valve. The drawback is that the valve provides noise isolation only during idling and deceleration.

It is desirable to insulate intake noise over the entire engine rotation range. However, if the intake passage is throttled by the intake throttle valve over the entire rotational range of the engine, a loss of intake pressure occurs during load operation where engine output is desired, making it impossible to obtain the required engine output.

Therefore, the present invention reduces intake noise by narrowing the intake passage as much as possible in the low rotation range where the area of the intake passage is large enough relative to the intake air pipe to prevent engine output from decreasing even if the intake passage is narrowed. The purpose is to prevent pressure loss by releasing the restriction of the intake passage and opening the intake passage in case of operating conditions where there is a concern that reducing the intake passage area will cause a drop in engine output due to a large amount of intake air. shall be.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention includes a valve body that is provided in the middle of the intake passage of an engine and blocks combustion noise of the engine by blocking the intake passage, and a first atmospheric chamber and a first negative pressure chamber. a vacuum motor, which 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 first negative pressure chamber of the vacuum motor. a negative pressure source that generates a negative pressure to guide the air, and an on-off valve that adjusts the amount of air flowing into the first negative pressure chamber, which is displaced by the differential pressure between the second atmospheric chamber and the second negative pressure chamber, and a negative pressure control valve having a second diaphragm supporting an on-off valve; a means for introducing negative pressure downstream of the valve body in the intake passage into the second negative pressure chamber; means for controlling the operation of the opening/closing valve accordingly, and the amount of atmospheric air flowing into the first negative pressure chamber is controlled depending on the negative or positive in the second negative pressure chamber to control the opening amount of the valve body. In an operating state where engine output is required, the on-off valve is opened by the means for controlling the operation of the on-off valve, and the first on-off valve is opened.
The present invention is characterized in that the negative pressure flowing into the negative pressure chamber is nullified so that the opening amount of the valve body is increased.

[Effect]

According to the configuration described in ``-'', in the low rotation range where the area of the intake passage is large enough relative to the amount of intake air and the engine output does not decrease even if the intake passage is throttled, the negative pressure downstream of the valve body in the intake passage becomes Since the amount of atmospheric air flowing into the first negative pressure chamber is controlled by the negative and positive values in the second negative pressure chamber, the opening amount of the valve element is reduced, and the intake passage is closed as much as possible. In operating conditions where there is a large amount of intake air and there is a concern that reducing the intake passage area may reduce engine output, the means for controlling the operation of the on-off valve can be used to open the valve body. Since the valve volume increases and the intake passage is opened, pressure loss can be prevented.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on the drawings.

FIG. 1 shows a first embodiment of the present invention.
is a diesel engine, and fresh air is taken into a combustion chamber (not shown) of this diesel engine 1 through an intake pipe 2, and exhaust gas is discharged through an exhaust pipe 3.

An air cleaner 4 is disposed at the upstream end of the intake pipe 2, and the air cleaner 4 removes dust, clumps, etc. from the fresh air taken in from the intake port 5.

A valve body 6 for opening and closing the passage of the intake pipe 2 is provided in the middle of the passage, and the valve body 6 is connected to a vacuum motor 10 via a connecting shaft 7.

The vacuum motor 10 moves the inside of the first casing 11 into a first
The diaphragm 12 divides the chamber into a first negative pressure chamber 13 and a first atmospheric chamber 14 . First diaphragm 1
The outer peripheral end of 2 is held by the first casing 11, and the center part thereof is held by a holding plate (not shown). This holding plate is fixed to the connecting shaft 7, so that the displacement of the first diaphragm 2 is transmitted to the valve body G via the connecting shaft 7, causing the valve body 6 to rotate.

The first diaphragm 12 is placed in the first negative pressure chamber 13.
A first spring 15 that presses toward the atmospheric chamber 14 side.
is accommodated. Atmospheric air is introduced into the first atmospheric chamber 14 through an atmospheric opening hole 1B, and the first negative pressure chamber 13 is connected to a vacuum pump 9 through a negative pressure passage 8.
Negative pressure is introduced from Note that the vacuum pump 9 is driven by the engine 1.

An orifice 17 is formed in the middle of the negative pressure passage 8, and the side closer to the vacuum motor 10 than this orifice 17 is branched, and this branch passage! 8 communicates with the second atmospheric chamber 24 of the negative pressure control valve 20.

The negative pressure control valve 20 controls the inside of the second casing 21 by means of second and third diaphragms 22 and 23.
It is divided into an atmospheric chamber 24, a pressure chamber 25, and a second negative pressure chamber 2B.

The outer peripheral ends of the second and third diaphragms 22 and 23 are sandwiched between the second casing 21 and the third diaphragm 23 has a larger a-effect pressure receiving area than the second diaphragm 22.

The branch passage 18 is located in the center of the second diaphragm 22.
An on-off valve 27 made of rubber or the like is fixed opposite the open end of the valve. This on-off valve 27 opens and closes the branch passage (2) 8 according to the displacement of the second diaphragm 22.

A connecting rod 28 is fixed to the second diaphragm 22 on the back side of the on-off valve 27, and the tip of the connecting rod 28 is connected to the center of the third diaphragm 23 via a presser plate (not shown). Fixed.

Therefore, the second diaphragm 22 and the third diaphragm 2
3 are always kept at a constant distance from each other via a connecting rod 28, and when the third diaphragm 23 is displaced, the opening/closing valve 27 is operated via the second diaphragm 22.

The atmosphere is introduced into the second atmospheric chamber 24 through another atmosphere opening hole 29, and the exhaust pressure of the exhaust pipe 3 is introduced into the pressure chamber 25 through an exhaust pipe communication passage 30. It looks like this. Further, the negative pressure inside the intake pipe 2 on the engine 1 side (downstream side) with respect to the valve body 6 is guided to the second negative pressure chamber 26 via the intake pipe communication passage 31.

A second spring 32 that presses and biases the third diaphragm 23 toward the pressure chamber 25 is housed in the second negative pressure chamber 2B. When the pressing force of the second spring 32 and the pressure within the pressure chamber 25 and the second negative pressure chamber 26 are balanced, the on-off valve 27 is stopped at that position.

The operation of the first embodiment having such a configuration will be explained.

Before the engine 1 is started, the vacuum pump 9 is not operating, and the first diaphragm 12 of the vacuum motor 10 is moved toward the first atmospheric chamber 14 by the biasing force of the first spring 15. This movement of the first diaphragm 12 is transmitted to the valve body B via the connecting shaft 7, and the valve body 6 fully opens the passage of the intake pipe 2. Note that at this time, the third diaphragm 23 of the negative pressure control valve 20 has been moved toward the pressure chamber 25 by the urging force of the second spring 32.
Therefore, the second diaphragm 2 is connected via the connecting rod 28.
2 is also moved to the second atmospheric chamber z4 side, and the on-off valve 27 contacts the open end of the branch passage 18 to close the branch passage 18.

When the engine 1 is started, the vacuum pump 9 also begins to operate, and the negative pressure generated by the vacuum pump 9 is introduced into the first negative pressure chamber 13 of the vacuum motor 10 through the negative pressure passage 8.

Then, the first diaphragm 12 receives this negative pressure, and the first diaphragm 12 receives this negative pressure.
The first diaphragm 12 resists the urging force of the spring 15.
moves to the first negative pressure chamber 13 side. The amount of movement of this first diaphragm 12 is controlled by the valve body 6 via the connecting shaft 7.
The valve body 6 is rotated to close the intake pipe 2.

When the valve body 6 closes the intake pipe 2, the negative pressure in the intake pipe 2 on the downstream side of the valve body 6 increases, and this increased negative pressure flows through the intake pipe communication passage 31 to the second negative pressure of the negative pressure control valve 20. It is introduced into the pressure chamber 2G. Therefore, the third diaphragm 23 of the negative pressure control valve 20 is moved toward the second negative pressure chamber 26 against the biasing force of the second spring 32, and is therefore opened and closed via the connecting rod 28 and the second diaphragm 22. Valve 27 to branch passage 18
The branch passage 18 is separated from the open end of the second atmospheric chamber 24.
open to

Then, the atmosphere introduced into the second atmospheric chamber 24 through the atmosphere opening hole 29 is introduced into the first negative pressure chamber 13 of the vacuum mode plO through the branch passage 18 and the negative pressure passage 8.
The negative pressure within this first negative pressure chamber 13 is weakened by the atmosphere.

Therefore, the first diaphragm 12 is moved toward the first atmospheric chamber 14, and the valve body 8 is rotated to open the intake pipe 2. In this case, the negative pressure in the first negative pressure chamber [3 causes the first diaphragm 1 to
The first diaphragm 12 stops at a position where the force received by the first diaphragm 2 balances the biasing force of the first spring 15, and the valve body B maintains its opening degree.

The opening amount of the valve body 6 is determined in this way. Now, let us consider a case where the negative pressure control valve 20 is not provided with the second diaphragm 22 and the pressure chamber 25 is not formed.

When the engine 1 rotates at low to medium speeds (for example, 2000 rpm or less), the negative pressure generated in the intake pipe 2 is small, and the negative pressure guided to the second negative pressure chamber 2B is also small, so the branch passage 1B is connected to the on-off valve 27. Closed by. Therefore, all the negative pressure from the vacuum pump 9 is introduced into the first negative pressure chamber 13,
When the first diaphragm 12 is moved to the first negative pressure chamber (3 side), the opening amount of the valve body B is determined by the negative pressure generated in the intake pipe 2 being controlled by the negative pressure control valve 20 to a constant negative pressure value. The pressure is reduced to a constant negative pressure (shown by the broken line in Figure 2). This blocks intake noise from being emitted from the intake port 5.

On the other hand, when the engine 1 reaches high rotation speed (for example, 200 rpm or more), the negative pressure inside the intake pipe 2 increases, and the second negative pressure chamber 2
Since a large negative pressure is applied to 6, the on-off valve 27 opens the branch passage 18. As a result, the first
The negative pressure in the negative pressure chamber 13 is diluted, and the first diaphragm 1
2 is moved to the first atmospheric chamber 14 side, and the valve body 6 increases its opening amount. However, in this case, when the valve body 6 tries to fully open the intake pipe 2, the pressure inside the intake pipe 2 becomes approximately equal to atmospheric pressure, so the on-off valve 27 closes the branch passage 18, and the first negative pressure chamber 13
All the negative pressure from the vacuum pump 9 acts on the valve body 6.
decreases its opening. In other words, the valve body 6 is adjusted such that the negative pressure downstream of the valve body 6 in the intake pipe 2 is always at a certain value (the constant value indicated by the broken line in Figure 2) according to the amount of intake air. Adjust the opening angle, or in other words, the tilt angle. However, since the valve body 6 is never fully opened, the combustion noise insulation effect is maintained.

When the engine 1 rotates at a higher speed, the amount of intake air increases, and even if the passage area is fully opened, the negative pressure in the intake pipe 2 rises to more than the set value of the negative pressure control valve 2o. A large negative pressure is applied to the pressure chamber 26, and the on-off valve 27 fully opens the branch passage 18. Therefore, almost no negative pressure is generated in the first negative pressure chamber 13 of the vacuum motor 10,
The first diaphragm 12 is moved to the first atmospheric chamber 14 side,
The valve body 6 becomes fully open.

” - If the negative pressure control valve 20 described above is not provided with the second diaphragm 22 and the pressure chamber 25 is not formed, the valve body 6
However, since the opening degree is adjusted according to the magnitude of the negative pressure downstream of the valve body 6 in the intake pipe 2, the pressure loss is reduced as shown by the broken line in FIG. We try to keep it constant, as shown in . However, in such a region of constant pressure loss, it is not possible to further improve the combustion noise insulation effect or to produce a high engine output.

On the other hand, when the second diaphragm 22 is provided in the negative pressure control valve 20 to form the pressure chamber 25 and the exhaust pressure of the exhaust pipe 3 is introduced into the pressure chamber 25 according to the present invention, the following effects occur.

Here, the set value of the control pressure at the negative pressure control valve 20 (the constant value indicated by the broken line in FIG. 2) is set higher. The relationship between the exhaust pressure of the exhaust pipe 3 and the engine rotational speed exhibits the characteristics shown in FIG. Therefore, when the engine is running at low speed,
The exhaust pressure is small, the pressure introduced into the pressure chamber 25 is small, and the force pushing the second spring 32 is small. Therefore, the branch passage 18 is closed by the on-off valve 27, all the negative pressure from the vacuum pump 9 is introduced into the first negative pressure chamber 13, and the opening amount of the valve body 6 is reduced to be less than the control value indicated by the broken line. When the value is high, the valve body B is controlled to be more closed, and the combustion noise insulation is greatly improved.

When the engine 1 rotates at a medium speed, the exhaust pressure gradually increases, and the pressure introduced into the pressure chamber 25 increases. here,
Since the effective pressure receiving area of the third diaphragm 23 is formed larger than that of the second diaphragm 22, the pressure chamber 25
The pressure introduced therein pushes the second spring 32 through the third diaphragm 23, so that the branch passage 18 is opened by the on-off valve 27.

Therefore, the negative pressure in the first negative pressure chamber 13 is weakened, and the valve body 6
increases the amount of valve opening, thus gradually reducing pressure loss.

When the engine 1 reaches a high rotation speed, the intake negative pressure and exhaust pressure become sufficiently large, and the second and third diaphragms 2
2.23 is greatly deformed and the on-off valve 27 is sufficiently separated from the branch passage 18, so that the branch passage 18 is opened to the atmosphere, negative pressure no longer acts in the first negative pressure chamber 3, and the valve body 6 is Keep it fully open.

As a result, when the engine 1 is running at low speeds, the passage area of the intake pipe 2 is narrowed and pressure loss increases, but the combustion noise is reduced by the narrowing of the passage area of the intake pipe 2 compared to the case of the broken line in Fig. The sound insulation effect increases.

When the engine 1 moves from medium speed to high speed, the passage area of the intake pipe 2 is expanded, reducing pressure loss and increasing engine output. Since the passage is fully opened, the required operating state of engine output can be obtained.

A second embodiment shown in FIG. 4 will be described.

In the case of this second embodiment, the second diaphragm 22 is formed to have a larger effective pressure area than the third diaphragm 23, and the pressure chamber 25 surrounded by the second diaphragm 22 and the third diaphragm 23 is It is connected to a venturi section 41 provided upstream of the valve body 6 of the intake pipe 2 via a communication passage 40 .

Even in the case of such a structure, when the engine reaches a high speed range, the negative pressure generated in the venturi section 41 increases, and in the pressure chamber 25 into which this negative pressure is introduced, the third diaphragm 2
Since the second diaphragm 22 has a larger self-receiving pressure area than the second diaphragm 22, the second diaphragm 22 is moved toward the pressure chamber 25, and the on-off valve 27 opens the branch passage 18 widely. Therefore, the opening of the valve body 6 is increased, and the passage area of the intake pipe 2 is expanded, so that pressure loss can be reduced.
Therefore, the engine output can be increased, and since the intake passage is fully opened early, the operating state that requires the engine output can be obtained.

A third embodiment shown in FIG. 5 will be described.

This device is constructed by dividing a negative pressure control valve 50 into an atmospheric chamber 24 and a negative pressure chamber 2G by a second diaphragm 22. A pressure control valve 51 is connected to the intake pipe communication passage 31 via a communication passage 57.

The pressure control valve 51 is controlled by a fourth diaphragm 52.
It is divided into an atmospheric chamber 53 and a second pressure chamber 54, and the third atmospheric chamber 53 is open to the atmosphere through an atmosphere opening hole 55, and the second pressure chamber 54 is opened to the atmosphere through an exhaust pipe communication passage 30. It is connected to the exhaust pipe 3.

The third atmospheric chamber 53 accommodates a third spring 5G, and is also provided with a second on-off valve 58 connected to the FF14 diaphragm 52, and this second on-off valve 58 is connected to the third atmospheric chamber. The opening end of the communication path 57 communicated with 53 is opened and closed.

In the case of such a configuration, when the engine l reaches a high speed range, the exhaust pressure increases, and this exhaust pressure is transferred to the second pressure chamber 54.
is guided to push the fourth diaphragm 52, and the second on-off valve 5
8 is brought into contact with the open end of the communicating path 57 to close the communicating path 57. Therefore, in the negative pressure control valve 50, the negative pressure introduced to the second negative pressure chamber 26 is no longer generated, and the second negative pressure chamber 26
Since the negative pressure in B increases, the on-off valve 27 is connected to the branch passage 1B.
open wide. Therefore, the opening amount of the valve body 8 increases, and the intake pipe 2
Since the passage area of the engine is expanded, pressure loss can be reduced, and engine output can therefore be increased.

In the case of the fourth embodiment shown in FIG. 6, a pressure control valve θ0 substantially similar to the pressure L control valve 51 is connected between the atmospheric chamber 24 of the negative pressure control valve 50 and the venturi section 41. . However, this pressure control valve 60 connects the third spring 56 to the second
It is housed in a pressure chamber 54.

Even with this configuration, since the opening/closing valve 27 is opened when the venturi negative pressure increases, the opening amount of the valve body 6 increases, and the passage area of the intake pipe 2 is expanded, thereby reducing pressure loss.

The fifth embodiment shown in FIG. 7 has a structure in which the on-off valve 27 is controlled in conjunction with the accelerator pedal.

That is, the negative pressure control valve 20 of this embodiment is similar to that of the second embodiment (
4), and this negative pressure control valve 2
0 pressure chamber 25 is connected to an accelerator pedal interlocking control valve 70.

In the accelerator pedal interlocking control valve 70, when a lever 71 that is interlocked with an accelerator pedal (not shown) is rotated, a cam 72 is rotated.
is moved. When the valve seat 74 is moved downward in the figure, the valve body 7B, which is held by the valve seat 74 via a spring 75, moves away from the open end of the negative pressure introduction pipe 77, and is thereby separated by a diaphragm 78. Negative pressure introduction chamber 79 becomes negative pressure. Since the negative pressure introduction chamber 79 is communicated with the pressure chamber 25 of the negative pressure control valve 20 through the conduction path 80, the pressure chamber 25
becomes negative and positive. Therefore, in the pressure chamber 25, since the effective pressure receiving area of the second diaphragm 22 is formed larger than that of the third diaphragm 23, the second diaphragm 22 is moved to the pressure chamber 25 side, and the on-off valve 27 expands the branch passage 18. open.

Therefore, the opening amount of the valve body B increases and the passage area of the intake pipe 2 is expanded, so that pressure loss can be reduced and engine output can be increased.

In addition, in the case of a structure like the above-mentioned first to fifth embodiments,
The valve body 6 operated by the vacuum motor IO may be installed upstream of the air cleaner 4 as in the sixth embodiment shown in FIG.

Furthermore, the present invention can also be implemented in engines that use turbochargers. In engines that use a turbocharger, when the turbocharger is activated, it is an attempt to increase engine output, and in such cases, if the intake pipe is constricted, supercharging will not work and the purpose of the turbocharger will not be achieved. It disappears.

Therefore, for example, a configuration like the seventh embodiment shown in FIG. 9 can be adopted. That is, in FIG. 9, 90 is a turbocharger, and the negative pressure control valve 2° has the same structure as in the first embodiment. Pressure chamber 25 of negative pressure control valve 20
is connected to a position between the turbocharger 90 and the valve body 6 in the intake pipe 2 via a positive pressure introduction path 91 .

According to such a configuration, when the turbocharger 90 does not operate, the characteristics shown by the broken line in FIG. Positive pressure is generated within the intake pipe 2 due to supercharging. This positive pressure is introduced into the pressure chamber 25 of the negative pressure control valve 2o through the positive pressure introduction path 91, pushes the second spring 32 through the third diaphragm 23, and is therefore activated by the opening/closing valve 27 of the branch passage 18. open. Therefore, the negative pressure in the first negative pressure chamber 13 is weakened, and the valve body 6 fully opens the intake pipe 2.

As a result, when the turbocharger 90 is not operating, intake noise is insulated, and when the turbocharger 90 is operating, the intake passage is sufficiently opened to reduce power loss in the intake passage and increase engine output. .

Further, it may be configured as in the eighth embodiment shown in FIG. 10.

When the turbocharger 90 operates, the positive pressure of the intake pipe 2 is applied to the diaphragm actuator 100 via the positive pressure introduction path 91, and the actuator 100
The valve body 103 is actuated by the lever l(]2 through the diaphragm 101 of the negative 1F passage 8. The valve body 103 opens another branch passage 104 branched from the negative 1F passage 8.

The valve body 103 connects the branch passage 104 to the atmosphere opening hole 105 and opens the negative pressure passage 8 to the atmosphere. Therefore, even if the on-off valve 27 is closed, the negative pressure passage 8 and the other branch passage 104 are opened to the atmosphere, so the first negative pressure chamber 13
The valve body 6 fully opens the intake pipe 2 by weakening the negative pressure inside.

〔Effect of the invention〕

As explained above, according to the present invention, in the low rotation range where the intake passage area is large enough for the amount of intake air and the engine output does not decrease even if the intake passage is narrowed, the intake passage is narrowed as much as possible, thereby reducing intake noise. It becomes possible to reduce
In addition, in operating conditions where the amount of intake air is large and there is a concern that reducing the intake passage area will cause a drop in engine output, the intake passage restriction is released and the intake passage is opened, reducing pressure loss and increasing engine output. can be increased.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the first embodiment of the present invention, FIGS. 2 and 3 are characteristic diagrams, and FIGS. 4 to 10 show the second to eighth embodiments of the present invention, respectively. FIG. I...Diesel engine, 2...Intake pipe, 3...
・Exhaust pipe, 6...valve body, 9...vacuum pump,
10... Vacuum motor, 12... First diaphragm, 13... First negative pressure chamber, 14... First atmospheric chamber,
18... Branch passage, 20°50... Negative pressure control valve, 2
2.23...Diaphragm, 24...Second popular chamber,
25...Pressure chamber, 26...Second negative pressure chamber, 27...Opening/closing valve, 30...Exhaust pipe communication passage, 31...Intake pipe communication passage, 41...Venturi section, 70...・Accelerator pedal interlocking control valve, 90...turbocharger. Applicant's agent Patent attorney Takehiko Suzue Figure 1 E/G number of houses pm) Inhalation! Input 1k (msiy + in) Fig. 2 ε/Gl Sanko comparison - (rpm) Fig. 3 Fig. 5

Claims (5)

[Claims] (1) A valve body is provided in the middle of the intake passage of the engine and insulates the combustion noise of the engine by blocking the intake passage, and a first atmospheric chamber and a first negative pressure chamber are divided into a vacuum motor that has a first diaphragm that is displaced by differential pressure and transmits this displacement to the valve body to operate the valve body; and a negative pressure that generates negative pressure that is guided to a first negative pressure chamber of the vacuum motor. a second diaphragm that has an on-off valve that regulates the amount of air flowing into the first negative pressure chamber, is displaced by a pressure difference between the second atmospheric chamber and the second negative pressure chamber, and supports the on-off valve; a negative pressure control valve comprising: a means for introducing negative pressure downstream of the valve body in the intake passage into the second negative pressure chamber; and means for operating the on-off valve in response to a request for output operation of the engine. controlling means so that when the negative pressure in the second negative pressure chamber increases, the amount of atmospheric air flowing into the first negative pressure chamber increases and the opening amount of the valve body decreases; An intake noise reduction device characterized in that, in an operating state that requires a large amount of intake air, the amount of opening of the valve body is increased by means for controlling the operation of the on-off valve. (2) Claim 1, characterized in that the means for controlling the operation of the on-off valve in response to a request for output operation of the engine has a structure in which the on-off valve is actuated by introducing exhaust pressure.
Intake noise reduction device as described in section. (3) The means for controlling the operation of the on-off valve in response to the engine output operation request operates the on-off valve by introducing venturi negative pressure from a venturi section provided upstream of the above-mentioned valve body in the intake passage. 2. The intake noise reduction device according to claim 1, wherein the intake noise reduction device has a structure in which: (4) The means for controlling the operation of the on-off valve in response to a request for output operation of the engine has a structure that operates the on-off valve in conjunction with an accelerator pedal. Intake noise reduction device. (5) In engines equipped with a turbocharger,
The means for controlling the operation of the on-off valve in response to a request for output operation of the engine is characterized in that it operates the on-off valve by introducing positive pressure generated downstream of the turbocharger in the intake passage. An intake noise reduction device according to claim 1.