JP2000054924A - Air intake duct - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture an inexpensive air intake duct capable of reducing air intake noise when an engine speed is low, and capable of taking in the sufficient amount of air when the engine speed is high, without an electronic control circuit or solenoid open/close valve. SOLUTION: When vacuum of a second duct 2 is a predetermined value or less, angular moment by a spring 42 is larger than angular moment by the vacuum in a cam 4, so that the second duct 2 is closed by a valve 3. When the vacuum of the second duct 2 is more than the predetermined value, the angular moment by the vacuum is larger than the angular moment by the spring 42, so that the second duct 2 is opened by the valve 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake duct as a passage for supplying air to an engine, and more particularly to an intake duct with reduced noise during intake.

[0002]

2. Description of the Related Art In an intake system of an automobile engine, there is a problem that noise is generated in an intake duct during intake.
This intake noise is particularly harsh when the engine is running at a low speed. Therefore, conventionally, a side branch and / or a resonator is provided in an intake duct to reduce noise of a specific frequency calculated based on Helmholtz's resonance theory or the like.

However, the side branch has a length of about 30 cm when it is long, and a resonator having a large volume as large as 14 liters. As a result, the space occupied by the sound absorbing devices in the engine room becomes large, and the degree of freedom in mounting other components is reduced. Thus, Japanese Utility Model Laid-Open Publication No. 64-22866 discloses that an orifice is arranged in an intake duct, and intake air is reduced at the position of the orifice to reduce intake noise. By narrowing the intake passage in this way, the acoustic mass increases, and the intake sound in a low-frequency range can be reduced.

In Japanese Utility Model Laid-Open Publication No. 3-43576, two intake pipes connected in parallel to an air cleaner case, branch pipes branched from the two intake pipes, and branch pipes are connected together. An intake noise reduction device is disclosed that has a common resonator and an open / close valve that is selectively opened in accordance with an operation state on the upstream side of a connection portion of a branch pipe in one intake pipe.

According to the apparatus disclosed in Japanese Utility Model Laid-Open Publication No. 3-43576, the on-off valve is controlled in accordance with the engine speed to switch the intake pipe to one or two pipes, whereby the engine is controlled in accordance with the engine speed. The intake air amount can be controlled, and the intake noise can be reduced.

[0006]

However, the above-described method of narrowing the intake passage has a disadvantage that the amount of intake air is insufficient at the time of high-speed rotation of the engine and the output is reduced. In the device disclosed in Japanese Utility Model Laid-Open Publication No. 3-43576, there is a state in which the on-off valve is held in a state from the fully closed state to the fully opened state or from the fully opened state to the fully closed state. In some cases, there is a case where the time when there is a gap between the intake pipe and the on-off valve is long. In such a case, since the intake noise leaks from the gap, there is a problem that a low-frequency muffled sound can be heard inside the vehicle.

Further, in the apparatus disclosed in Japanese Utility Model Laid-Open No. 3-43576, an electronic control circuit, an electromagnetic on-off valve, a diaphragm actuator, or the like is used to drive the on-off valve, so that the number of parts is large and complicated. It is not preferable in terms of cost. The present invention has been made in view of such circumstances, and reduces intake noise at the time of low-speed rotation of an engine and prevents generation of low-frequency muffled sound without using an electronic control circuit or an electromagnetic switching valve. Along with
It is an object of the present invention to provide an inexpensive intake duct that can inhale a sufficient amount of air during high-speed rotation.

[0008]

According to a first aspect of the present invention, there is provided an air intake duct serving as a passage for supplying air to an engine, comprising a first air intake passage, a second air intake passage, and a second air intake passage. An opening / closing member slidably provided in the second intake passage for opening and closing the second intake passage;
A biasing member for biasing the intake passage in a closing direction, a swing center point interposed between the opening / closing member and the biasing member, a swing center of the opening / closing member being fixed, and a swing center point provided apart from the swing center point. A cam having an action point on which the urging force of the urging member acts,
When the negative pressure in the second intake passage is equal to or lower than a predetermined value, the rotational moment due to the urging force of the urging member is larger than the rotational moment due to the negative pressure at the point of action, and the opening / closing member closes the second intake passage. When the negative pressure in the passage exceeds a predetermined value, the rotational moment due to the negative pressure at the point of action is larger than the rotational moment due to the urging force of the urging member, so that the opening / closing member opens the second intake passage. .

According to a second aspect of the present invention, in the intake duct according to the first aspect, the second intake passage has a swinging end face of the opening and closing member when the opening and closing member opens the second intake passage. It has a guide surface for guiding in close proximity.
Further, the intake duct according to claim 3 is characterized in that the second intake passage has a locking surface which comes into contact with the opening / closing member when the opening / closing member closes the second intake passage, and when the opening / closing member separates from the locking surface. To provide a resistance means for giving a resistance to the object.

[0010]

In the intake duct according to the present invention, when the engine is running at a low speed, the negative pressure in the second intake passage is equal to or lower than a predetermined value. The rotational moment due to the urging force of the urging member is greater than the moment, and the swinging of the cam causes the opening / closing member to close the second intake passage and open only the first intake passage. Therefore, in the case of low-speed rotation, the intake passage is narrowed, and the sound mass increases, so that the intake sound in the low-frequency range is reduced.

When the engine rotates at high speed, the second
Since the negative pressure of the intake passage exceeds a predetermined value, the rotational moment due to the negative pressure becomes larger than the rotational moment due to the urging force of the urging member at the point of action of the cam, and the opening / closing member moves the second intake passage by swinging the cam. open. As a result, the intake passage is enlarged, so that a sufficient amount of air can be supplied to the engine during high-speed rotation.

In order to further improve the above operation, it is preferable to reduce the opening area of the first intake passage and increase the opening area of the second intake passage. Further, in the case where the intake duct has a branch structure, for example, when the intake duct has two intake passages each having a first intake passage and a second intake passage and merges in the middle to become one, a It is preferable that the intake passage having the first intake passage is made thinner to further increase the acoustic mass, and the intake passage having the second intake passage is made thicker to supply a sufficient amount of air.

Examples of the opening / closing member include a valve that opens and closes the second intake passage by swinging. Further, as the urging member, various members can be selected, such as a member using a force by gravity and a member using a force by a spring force. Although a side branch or a resonator may be provided, according to the intake duct of the present invention, intake sound in a low frequency range can be reduced without providing a side branch or a resonator. Therefore, in order to reduce the space occupied in the engine room and to improve the degree of freedom in mounting other components, it is desirable not to provide a side branch or a resonator.

When the opening / closing member closes the second intake passage, the predetermined value F ₁ of the negative pressure in the second intake passage is equal to the second pressure,
The predetermined value F ₂ of the negative pressure when opening the intake passage, F ₁ ≦ F
_In a relationship of ₂ . If the difference between F ₁ and F ₂ is small, may cause noise closing member is open and close member when opening the second intake passage flapping, the intake air amount difference F ₁ and F ₂ is too large May be insufficient. Therefore, F ₁ and F ₂
, The urging force of the urging member, etc. must be carefully determined.

By the way, when the opening / closing member swings due to a large intake negative pressure, the opening / closing member swings slowly at first with the increase of the engine speed, and then swings at a stretch to become a fully open state. There is a state where the opening / closing member is slightly opened in the initial period of the swing, though it is a short time. Therefore, there is a problem that the intake sound leaks from the gap between the opening / closing member and the second intake passage during that time.

Therefore, in the intake duct according to the second aspect,
The second intake passage has a guide surface for guiding the opening / closing member close to the swing end surface when the opening / closing member opens the second intake passage. Therefore, even if the opening / closing member initially swings slowly with an increase in the engine speed, the swinging end face of the opening / closing member moves close to the guide surface, so that there is a gap between the opening / closing member and the second intake passage. Is prevented from occurring, and leakage of the intake sound can be prevented.

Further, in the above-mentioned intake duct, when the opening / closing member slightly opens the second intake passage, vibration occurs in the opening / closing member, which causes an abnormal noise. This is because the intake air suddenly passes through a space having a small cross-sectional area between the opening / closing member and the second intake passage, and when the difference between the urging force by the urging member and the intake negative pressure is small, the opening / closing member is in that state. This is because the pulsating time becomes longer, and the pulsation of the intake air from the engine body is easily transmitted to the opening / closing member, whereby the opening / closing member vibrates.

Therefore, in the intake duct according to the third aspect,
The second intake passage has a locking surface that comes into contact with the opening / closing member when the opening / closing member closes the second intake passage, and includes a resistance unit that applies resistance when the opening / closing member separates from the locking surface.
With this configuration, when the intake negative pressure increases and the differential pressure between the biasing force of the biasing member and the intake negative pressure increases, and the opening / closing member attempts to swing in the direction to open the second intake passage, the resistance is increased. Since the resistance force from the means acts, the opening and closing member keeps the second intake passage closed until the differential pressure exceeds the resistance force from the resistance means. Then, when the differential pressure exceeds the resistance of the resistance means, the opening / closing member swings at a stretch to open the second intake passage.

Therefore, according to this intake duct, the time for forming a space having a small cross-sectional area between the opening / closing member and the second intake passage can be extremely shortened, so that noise caused by vibration of the opening / closing member can be prevented. Can be. As the resistance means, a means for attracting the opening / closing member such as a permanent magnet or an electromagnet, or a biasing means such as a spring, a damper, and the weight of the opening / closing member can be used.

[0020]

The present invention will be specifically described below with reference to examples and comparative examples. (Comparative Example) FIG. 18 shows an intake duct of a comparative example. This intake duct corresponds to that disclosed in Japanese Utility Model Laid-Open Publication No. 3-43576, and has a first intake passage 100 having a small diameter and a second intake passage 200 having a large diameter. It is pivoted freely. The pivot shaft of the valve 300 is connected to the center of the disc-shaped cam 400, and the other end of the spring 500, which is fixed at one end, is fixed to the periphery of the cam 400. The spring 500 is configured such that the biasing force is minimized when the valve 300 closes the second intake passage 200 fully.

In this intake duct, while the intake negative pressure in the second intake passage 200 is smaller than a predetermined value, the valve 300 is connected to the second intake passage 200.
The intake sound in the low-frequency range is reduced because the intake port 200 is in the fully closed state and the intake is performed only from the first intake passage 100. Then, when the intake negative pressure exceeds a predetermined value, the valve 300 moves in proportion to the intake negative pressure.
It swings against the urging force of the spring 500 transmitted through 400, and the opening area of the second intake passage 200 increases, so that a sufficient amount of air is secured.

However, in the intake duct of this comparative example, there is a state in which the valve 300 is held in a state from the fully closed state to the fully opened state or from the fully opened state to the fully closed state. There may be a case where the time between the second intake passage 200 and the valve 300 with a gap is long. In such a case, since the intake noise leaks from the gap, there is a problem that a low-frequency muffled sound can be heard inside the vehicle.

(Embodiment 1) FIG. 1 is an explanatory view of the structure of the intake duct of this embodiment. In this intake duct, a first intake passage 1 having a small diameter and a second intake passage 2 having a larger diameter than the first intake passage 1 are joined to constitute an intake duct. In addition,
FIG. 1 does not show a junction between the first intake passage 1 and the second intake passage 2.

The cross-sectional area of the first intake passage 1 corresponds to the cross-sectional area of a φ40 pipe, and the cross-sectional area of the second intake passage 2 corresponds to the cross-sectional area of a φ70 pipe. Also the first
The distance from the opening end of the intake passage 1 to the junction is longer than the distance from the opening end of the second intake passage 2 to the junction. In the second intake passage 2, a valve 3 as an opening / closing member is pivotally supported on a pipe wall so as to be swingable.

The center of a disk-shaped cam 4 is connected to a pivot shaft (swinging shaft) of the valve 3, and the valve 3 is swung by the rotation of the cam 4. A long hole 40 extending in the radial direction from the vicinity of the center is formed in the cam 4, and the slide pin 41 is movably engaged with the long hole 40 between points a and b at both ends of the long hole 40. I have. In the present embodiment, the slide pin 41 constitutes the action point according to claim 1. The other end of a spring 42 having one end fixed to the slide pin 41, and the spring 42 urges the slide pin 41 to be pulled.

Since the fixed position of one end of the spring 42 is located at an offset position higher than the point a at the outermost peripheral portion of the long hole 40, the slide pin 41 always moves in the long hole 40 toward the point a. The cam 4 is biased so that the valve 3 swings in a direction to close the second intake passage 2. FIG. 2 is a diagram illustrating a state in which the intake negative pressure Q in the second intake passage 2 is large and the valve 3 fully opens the second intake passage 2 in the intake duct of the present embodiment configured as described above.
Shown in At this time, the slide pin 41 is located at the point b closest to the center point P of the long hole 40. When the distance from the point b to the center point P is B and the spring force of the spring 42 is F, the rotation moment at which the spring 42 tries to rotate the cam 4 is simply expressed as FB by omitting the trigonometric function. So that
If Q> FB, this state is maintained and the second intake passage 2
Are kept fully open.

Therefore, if the valve 3 keeps the second intake passage 2 fully opened, the intake air is mainly taken in through the thick and short second intake passage 2, thereby avoiding the problem that the intake air amount is reduced. . In addition, the intake noise is not intermingled with the engine sound and does not become unpleasant noise. When the intake negative pressure Q decreases and Q <FB, the slide pin 41 is always urged by the spring 42 to move toward the point a.
The cam 4 rotates by the movement in the 40, the valve 3 swings, and the second intake passage 2 is gradually closed. Accordingly, the distance between the slide pin 41 and the center point P gradually increases, so that the rotational moment by the spring 42 gradually increases, and the difference from the intake negative pressure Q further increases. Accordingly, the valve 3 swings at an accelerated direction in the direction in which the second intake passage 2 is closed.

When the valve 3 comes into contact with the locking projection 21 provided in the second intake passage 2 and is fully closed, the swing of the valve 3 is restricted, and as shown in FIG. Pin 41
Is located at the point a. In this state the spring
When the distance from the point a to the center point P is A, the rotational moment at which the cam 42 rotates the cam 4 is simply expressed as FA. Since B <A and FB <FA, Q <FB During this time, this state is maintained, and the valve 3 maintains the fully closed state of the second intake passage 2.

Therefore, since the air is sucked only from the first air intake passage 1 having a small diameter, the acoustic mass increases, and the intake sound in a low frequency range is reduced without using a resonator or the like. Even if the intake negative pressure Q increases and FB <Q <FA, the slide pin 41 is urged toward the point a with a force f because the spring 42 is at the offset position. Therefore, the valve 3 maintains the fully closed state. When the intake negative pressure Q further increases to satisfy FA + f <Q, the valve 3 swings and the slide pin 41 moves in the long hole 40, and the cam 4
Rotates. As the slide pin 41 moves, the rotational moment due to the spring 42 gradually decreases, and the difference from the intake negative pressure Q further decreases, so that the valve 3 swings at an accelerated speed and the second intake passage 2 is fully closed. State. Then, as described above, that state is maintained until Q <FB.

That is, according to the intake duct of this embodiment,
The valve 3 can be automatically maintained in the fully open and fully closed states in accordance with the intake negative pressure, and both the reduction of intake noise and the securing of a required intake amount can be achieved without using a resonator or the like. In addition, between the fully open state and the fully closed state, the valve 3 swings at an accelerated speed and there is almost no time in which there is a gap between the second intake passage 2 and the valve 3. Is prevented from occurring. And since it is a simple structure which did not require an electronic control, a diaphragm actuator, etc., it can be made highly reliable and low cost.

(Embodiment 2) FIG. 4 shows an intake duct according to a second embodiment of the present invention. This intake duct is
Is different from the first embodiment in that a weight 5 having a weight W is used instead of That is, the swing shaft of the valve 3 is connected to the center of the cam 4 as in the first embodiment. One end of the rail 6 is fixed to the cam 4 at a fixed point S eccentric from the center P, and the weight 5 is guided by the rail 6 so as to be movable on the rail 6. In the present embodiment, the fixed point S constitutes the action point according to claim 1.

In the intake duct of this embodiment, with the valve 3 in a state in which the second intake passage 2 is fully closed, as shown in FIG. 4, the tip of the rail 6 is slightly lowered from the horizontal position. becomes the position, the weight 5 is distance L is held at the tip of the rail 6 by the weight 6 and the fixed point S is configured to be the largest L _1. Therefore, if the intake negative pressure Q is smaller than the rotation moment WL ₁ acting from the weight 5 to the cam 4 (Q <W
In L ₁ ), the fully closed state of the second intake passage 2 of the valve 3 is maintained.

On the other hand, when WL ₁ <Q, the valve 3 swings and the cam 4 starts rotating. Then, the tip of the rail 6 where the weight 5 is located gradually moves upward, and when the position of the weight 5 becomes higher than the fixed point S, the weight 5 moves on the rail 6 in a direction approaching the fixed point S. As a result, the distance L between the weight 6 and the fixed point S decreases, and the rotational moment WL gradually decreases, so that the difference from Q gradually increases. Therefore, the valve 3 swings at an accelerated speed to bring the second intake passage 2 into a fully open state.

Assuming that the distance between the weight 6 and the fixed point S when the valve 3 is in the fully open position is L ₂ , the cam 4 rotates when the intake negative pressure Q decreases and Q <WL _2. At first, the valve 3 gradually closes the second intake passage 2. When the horizontal position of the weight 5 falls below the fixed point S, the weight 5 moves on the rail 6, so that L ₂ increases and the rotational moment WL ₂ increases at an accelerated rate. Therefore, the valve 3 swings at an accelerated speed and the second intake passage 2 is fully closed.

That is, also in the intake duct of the present embodiment, the valve 3 can be automatically maintained in the fully opened and fully closed state in accordance with the intake negative pressure similarly to the first embodiment, and the intake air can be supplied without using a resonator or the like. It is possible to achieve both reduction of sound and securing of a required intake air amount. Further, between the fully open state and the fully closed state, the valve 3 swings at an accelerated speed, and there is almost no time when there is a gap between the second intake passage 2 and the valve 3, so that a low-frequency muffled sound is generated as in the comparative example. Problems that may occur are prevented. And since it is a simple structure which did not require an electronic control, a diaphragm actuator, etc., it can be made highly reliable and low cost.

(Embodiment 3) In the above embodiment, the cam 4
5 is a conceptual one fixed to a pivot shaft of the valve 3 as shown in FIG. 5, but a fan-shaped cam 4 is integrated with the valve 3 as shown in FIG. If one end of the spring 42 is fixed to the wall surface of the second intake passage 2, it becomes practical.

In this example, since the cam 4 swings together with the valve 3, the torque from the valve 3 is directly transmitted to the cam 4. Therefore, there is no play between the components, and problems such as operation delay can be prevented. Further, since the number of parts is reduced, the cost can be reduced. As shown in FIG. 6, if the fan-shaped cams 4 are arranged on both sides of the side wall of the second intake passage 2 and the springs 42 are provided on each of the cams 4, the valve 3
Swing can be performed more accurately.

As shown in FIG. 7, if the fan-shaped cam 4 is arranged so as to be able to enter and exit the second intake passage 2 at the center of the second intake passage 2, one cam 4 and one spring 42 are provided. Thus, the swing of the valve 3 can be accurately performed. (Embodiment 4) In the above embodiment, the spring 42 is locked to only one end of the slide pin 41. Therefore, the axis of the slide pin 41 is inclined with respect to the peripheral wall surface of the long hole 40,
When the slide pin 41 moves in the elongated hole 40, the resistance is large, and a reliable operation may not be obtained.

Therefore, in this embodiment, as shown in FIG. 8, a pair of plate portions 43 opposed to each other are formed at intervals on the cam 4 integrated with the valve 3, and the pair of plate portions 43 are each provided with a long hole. 40
Is formed. The slide pin 41 is arranged between the pair of plate portions 43, and both ends of the slide pin 41 are elongated holes 40, respectively.
Move in. One end of a spring 42 is locked at the center of the slide pin 41.

With this configuration, both ends of the slide pin 41 move evenly in the elongated hole 40, so that the slide pin 41 has a small resistance when moving in the elongated hole 40, and a reliable operation can be obtained. . (Embodiment 5) In the example shown in FIG. 9, the spring 42 is locked to the ring member 6 with both ends of the ring member 6 pivotally supported at both ends of the slide pin 41, respectively. The cam 4 has a concave portion 45 that allows the ring member 6 to move.

In this example, the biasing force of the spring 42 acts uniformly on both ends of the slide pin 41 by the ring member 6. Therefore, since both ends of the slide pin 41 move evenly in the elongated hole 40, the resistance when the slide pin 41 moves in the elongated hole 40 is small, and a reliable operation can be obtained. Note that, as shown in FIG. 10, the same operation and effect as described above can be obtained by using two springs 42, each of which is locked to one end of the slide pin 41 and used in the intake duct shown in FIGS. .

(Embodiment 6) By the way, when the intake negative pressure increases and the valve 3 swings, the valve 3 first swings slowly as the engine speed increases, and then swings at an accelerated rate. As a result, the valve 3 is slightly opened at the beginning of the swing for a short time because the valve 3 is fully opened. Therefore, there is a problem that the intake sound leaks from the gap during that time.

In this embodiment, a recess 22 having a triangular cross section is provided on the bottom wall of the second intake passage 2 as shown in FIG.
The swing end 30 of the valve 3 is configured to be housed in the recess 22. The recess 22 has a locking surface 23 for locking the swinging end 30 of the valve 3 when the valve 3 is fully closed, and a guide surface along which the end surface of the swinging end 30 extends when the valve 3 swings. 24 and width L of guide surface 24
Corresponds to the movement distance of the swing end face while the valve 3 swings slowly.

Therefore, in the intake duct of the present embodiment, even when the valve 3 initially swings slowly with an increase in the engine speed, the swing end 30 of the valve 3 moves close to the guide surface 24 and moves to the second position. Since the formation of a gap between the intake passage 2 and the intake passage 2 is prevented, it is possible to prevent the intake noise from leaking from the gap.
If the cross-sectional shape of the guide surface 24 is an arc shape centering on the swing axis of the valve 3, the gap between the swing end 30 of the valve 3 can be further reduced, and the intake sound leaks from the gap. Can be further prevented. It is also preferable to attach a nonwoven fabric or the like around the valve 3 which is in sliding contact with the inner wall surface of the second intake passage 2. By doing so, the clearance between the inner wall surface of the second intake passage 2 and the inner wall surface is adjusted, so that the leakage of the intake noise due to the generation of the gap can be further prevented, and the impact noise due to rattling or the like is also prevented.

In the above embodiment, the second intake passage 2 has a concave portion.
22 is provided, but as shown in FIG.
The same operation and effect can be obtained. In the example shown in FIG. 12, a through hole 26 is provided in the bottom wall surface of the second intake passage 2. By providing the through-holes 26 in this manner, the water accumulated on the valve 3 and the pipe wall can be discharged from the through-holes 26, and the malfunction due to the adhesion of the water can be suppressed.

(Embodiment 7) However, in each of the above-mentioned embodiments, there was a problem that the valve 3 was vibrated when the valve 3 was slightly opened, thereby generating abnormal noise.
This is because the intake air suddenly passes through a space having a small cross-sectional area between the valve 3 and the second intake passage 2, and the differential pressure between the urging force of the spring 42 and the intake negative pressure is small, so that the valve 3 is in that state. This is because the pulsating time is relatively long, so that the pulsation of the intake air from the engine body is easily transmitted to the valve 3, which causes the valve 3 to vibrate.

Therefore, in this embodiment, as shown in FIG.
A permanent magnet 27 having a predetermined magnetic force is disposed on the surface of the concave portion 22 of the intake duct facing the valve 3 of the sixth embodiment described above.
The tip of the rocking end 30 has an iron piece on the surface facing the permanent magnet 27.
31 are joined. With this configuration, when the pressure difference between the biasing force of the spring 42 and the intake negative pressure is small, the iron piece 31 is attracted to the permanent magnet 27, and the valve 3 contacts the recess 22 so that the second intake passage 2 Is closed. When the suction negative pressure increases and the pressure difference between the biasing force of the spring 42 and the suction negative pressure exceeds the attraction force between the permanent magnet 27 and the iron piece 31, the valve 3 separates from the recess 22 and swings at a stretch. The second intake passage 2 is opened.

Therefore, according to the intake duct of the present embodiment, the time for forming a space having a small cross-sectional area between the valve 3 and the second intake passage 2 can be extremely shortened. Can be prevented. In the seventh embodiment, the permanent magnet 27 is arranged in the recess 22 and the iron piece 31 is joined to the valve 3. However, the same effect can be obtained by disposing the iron piece in the recess 22 and joining the permanent magnet to the valve 3. Is played. Further, an electromagnet may be used instead of the permanent magnet. In order to dispose the permanent magnet 27 or the iron piece 31 in the concave portion 22 or the valve 3, various known means such as insert molding and bonding can be adopted.

If the cross-sectional shape of the permanent magnet 27 is, for example, substantially triangular as shown in FIG. 14, the surface of the permanent magnet 27 can be used as a substitute for the locking surface 23 of the recess 22. (Embodiment 8) In the seventh embodiment, the magnetic force is used to prevent the vibration of the valve 3. However, as shown in FIG. A torsion spring 32 for urging the valve in the closing direction may be further arranged.

By setting the urging force of the torsion spring 32 to a predetermined value, when the pressure difference between the urging force of the spring 42 and the intake negative pressure is small, the urging force of the torsion spring 32 causes the valve 3 to move the permanent magnet 27. Pressed,
The valve 3 closes the second intake passage 2. Then, when the intake negative pressure increases and the pressure difference between the biasing force of the spring 42 and the suction negative pressure exceeds the biasing force of the torsion spring 32 and the magnetic force of the permanent magnet 27, the valve 3 separates from the permanent magnet 27 and swings at once. To open the second intake passage 2.

Therefore, according to the intake duct of this embodiment, the time for forming a space having a small cross-sectional area between the valve 3 and the second intake passage 2 can be extremely shortened. Can be prevented. In this embodiment, both the spring force and the magnetic force of the torsion spring 32 are used. However, it goes without saying that the same action can be exerted only by the spring force of the torsion spring 32.

(Embodiment 9) Instead of the magnetic force or the urging force of the torsion spring, the resistance force of the damper can be used. For example, as shown in FIG. 15, a pair of gears 32 and 33 meshing with each other is formed on a swing shaft of the valve 3 and a side wall of the second intake passage 2, and a damper mechanism 34 is provided inside one or both gears. It is built in. In FIG. 15, a gear 33 provided on the side wall of the second intake passage 2 has a damper mechanism 34 attached thereto.
Is built-in.

By setting the resistance of the damper mechanism 34 to a predetermined value, the valve 3 is opened by the resistance of the damper mechanism 34 when the differential pressure between the urging force of the spring 42 and the intake negative pressure is small. The valve 3 is in contact with the recess 22 and the second
The intake passage 2 is closed. When the suction negative pressure increases and the pressure difference between the biasing force of the spring 42 and the suction negative pressure exceeds the resistance of the damper mechanism 34, the valve 3 separates from the recess 22 and swings at a stroke to form the second intake passage. Open 2.

Therefore, according to the intake duct of this embodiment, the time for forming a space having a small sectional area between the valve 3 and the second intake passage 2 can be extremely shortened. Can be prevented. (Embodiment 10) In the intake duct of Embodiment 9 described above, the valve 3
, The resistance of the damper mechanism 34 always acts. For this reason, a problem that the response of the valve 3 is reduced occurs.

Therefore, in this embodiment, as shown in FIG. 16, one of the pair of gears 32, 33 (the gear 32 in FIG. 16) is a partial gear, and the valve 3 is slightly opened from a state in which the valve 3 is in contact with the surface of the concave portion 22. The configuration is such that the resistance of the damper mechanism 34 acts only until the state is reached. Therefore, in the intake duct of this embodiment, the same operation and effect as those of the ninth embodiment can be obtained, and the responsiveness of the valve 3 can be made equal to those of the other embodiments.

As shown in FIG. 17, a tooth 46 is provided on a part of the outer periphery of the cam 4 of the intake duct shown in FIG.
It is needless to say that the same operation and effect can be obtained even if the damper mechanism 34 having a tooth portion which meshes with the portion 46 is provided on the side wall of the second intake passage 2 or the like.

[0057]

According to the intake duct of the first aspect, the intake sound in a low sound range can be reduced when the engine is running at a low speed, and a sufficient amount of air can be taken in when the engine is running at a high speed. Since an electronic control circuit, an electromagnetic switching valve, a diaphragm actuator, and the like are not used, an inexpensive intake duct can be provided.

According to the intake duct of the second aspect, it is possible to reliably prevent the intake noise from leaking, and according to the intake duct of the third aspect, it is possible to prevent abnormal noise due to vibration of the opening / closing member. be able to.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of an intake duct according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an operation of the intake duct when the valve is fully opened according to one embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an operation of the intake duct when the valve is fully closed according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a configuration of an intake duct according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a configuration of an intake duct according to a third embodiment of the present invention.

FIG. 6 is an explanatory view showing another embodiment of the intake duct of the third embodiment of the present invention.

FIG. 7 is an explanatory view showing another embodiment of the intake duct of the third embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a configuration of an intake duct according to a fourth embodiment of the present invention.

FIG. 9 is an explanatory diagram showing a configuration of an intake duct according to a fifth embodiment of the present invention.

FIG. 10 is an explanatory diagram showing another embodiment of the intake duct of the fifth embodiment of the present invention.

FIG. 11 is an explanatory diagram illustrating a configuration of an intake duct according to a sixth embodiment of the present invention.

FIG. 12 is an explanatory diagram showing another embodiment of the intake duct of the sixth embodiment of the present invention.

FIG. 13 is a sectional view of a main part of an intake duct according to a seventh embodiment of the present invention.

FIG. 14 is a sectional view of a main part of an intake duct according to an eighth embodiment of the present invention.

FIG. 15 is a front view of a main part of an intake duct according to a ninth embodiment of the present invention.

FIG. 16 is a front view of a main part of an intake duct according to a tenth embodiment of the present invention.

FIG. 17 is a main part front view showing another mode of the intake duct of the tenth embodiment of the present invention.

FIG. 18 is an explanatory diagram illustrating a configuration of an intake duct of a comparative example.

[Explanation of symbols]

1: first intake passage 2: second intake passage 3: valve (opening / closing member) 4: cam 40: long hole 41: slide pin 42: spring (biasing member)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takahiro Komori 1 Ochiai Ogata, Kasuga-cho, Nishi-Kasugai-gun, Aichi Prefecture Inside Toyota Gosei Co., Ltd. No. 1 Toyoda Gosei Co., Ltd. (72) Inventor Tono Kino, etc. 1 Nagahata, Ochiai, Kasuga-machi, Nishikasugai-gun, Aichi Prefecture No. 1 Toyoda Gosei Co., Ltd. Within Gosei Co., Ltd. (72) Inventor Zenichi Yasuda 1 Ochiai, Nagahata, Kasuga-cho, Nishi-Kasugai-gun, Aichi Prefecture Inside Toyoda Gosei Co., Ltd. Inside the corporation

Claims (3)

[Claims] 1. An intake duct as a passage for supplying air to an engine, a first intake passage, a second intake passage, and a swingably provided in the second intake passage for opening and closing the second intake passage. An opening / closing member, an urging member for urging the opening / closing member in a direction to close the second intake passage, and a swinging member interposed between the opening / closing member and the urging member and having a swing shaft fixed to the opening / closing member. A cam having a moving center point and an action point provided at a distance from the swing center point and to which the urging force of the urging member acts, wherein the negative pressure of the second intake passage is equal to or less than a predetermined value. The opening / closing member closes the second intake passage, and the negative pressure of the second intake passage is smaller than a predetermined value by the opening / closing member, the rotational moment due to the urging force of the urging member being larger than the rotational moment due to the negative pressure at the point of action. Is exceeded, the rotational moment due to the negative pressure at the point of action is Intake duct increases the closing member from the rotation moment caused by the urging force of the wood is characterized by being configured to open the second intake passage. 2. The system according to claim 1, wherein the second intake passage has a guide surface for guiding the opening / closing member close to a swing end surface when the opening / closing member opens the second intake passage.
The intake duct as described in. 3. The second intake passage has a locking surface that comes into contact with the opening / closing member when the opening / closing member closes the second intake passage, and resists when the opening / closing member separates from the locking surface. The intake duct according to claim 1, further comprising a resistance means for applying a force.