JP6631315B2 - Intake device for internal combustion engine - Google Patents

Description

  The present invention relates to an intake device for an internal combustion engine that introduces exhaust gas into intake air.

Part of the exhaust gas exhausted from the internal combustion engine (hereinafter referred to as the engine) of the vehicle is introduced into the intake manifold, which is the intake passage of the engine, and is again sucked into the engine to reduce nitrogen oxides (NOx) in the exhaust gas and fuel consumption. 2. Description of the Related Art An intake device for an internal combustion engine for improving (thermal efficiency) is known.
Conventionally, exhaust gas is introduced into the intake manifold by using a negative pressure in the intake manifold.
Therefore, when the engine is under a low load, that is, when the throttle valve provided on the upstream side of the intake manifold is throttled, the pressure in the intake manifold sufficiently decreases, and the exhaust gas using the negative pressure in the intake manifold is reduced. The introduction of gas is performed smoothly.
On the other hand, when the engine is under a high load, that is, when the throttle valve is fully opened or almost fully opened, the intake air volume is large and the pressure in the intake manifold rises to approximately atmospheric pressure. This is disadvantageous in smoothly introducing the exhaust gas using the negative pressure.
On the other hand, Patent Literature 1 discloses an engine in which intake air is supercharged by a compressor of a supercharger, a supercharging recirculation passage for returning supercharging from an outlet to an inlet in a housing of the compressor, and supercharging recirculation flowing through the passage. Discloses a technique for forcibly introducing exhaust gas into an intake passage.

JP 2012-62822 A

However, the above prior art has a disadvantage that it is limited to an engine that supercharges intake air by a supercharger.
The present invention has been made in view of the above circumstances, and is advantageous in efficiently introducing exhaust gas into intake air regardless of the load of the internal combustion engine without using a supercharger. It is an object of the present invention to provide an air intake device.

In order to achieve the above object, the present invention provides an intake system for an internal combustion engine, comprising: an intake passage connected to an internal combustion engine; and an exhaust gas introduction pipe for introducing exhaust gas discharged from the internal combustion engine into the intake passage. an apparatus, comprising a swirl flow forming member which forms a swirling flow by the intake provided in the intake passage, an end portion of the exhaust gas inlet pipe, the exhaust gas in the radial center portion of the swirling flow forming section The swirl flow forming portion has an upstream portion that forms a swirl flow of the intake air and a downstream portion having a smaller diameter than the upstream portion, and an end of the exhaust gas introduction pipe is provided at the downstream portion. And a throttle valve disposed in the intake passage, wherein the upstream portion includes a cylindrical portion, and an upstream pipe connected to the throttle valve and connected tangentially to the cylindrical portion. And the downstream part is A reduced-diameter portion that gradually reduces the outer diameter of the swirling flow as the distance from the cylindrical portion increases; and a downstream pipe that is connected to the reduced-diameter portion and guides the reduced-diameter swirling flow downstream of the intake passage. characterized in that it is configured.
Further, the present invention is characterized in that the swirling flow forming portion has a diameter on the downstream side of the intake passage smaller than a diameter on the upstream side of the intake passage.
Further, the invention is characterized in that the exhaust gas introduction pipe is arranged along an axis of the swirling flow forming portion.
Further, in the present invention, the intake passage includes an intake manifold, the intake manifold includes a surge tank, and a plurality of branch pipes branched from the surge tank and connected to an intake port of the internal combustion engine, A space in the tank, which is inside the surge tank, extends along an extension of the axis of the downstream portion, and a portion where the plurality of branch pipes branch from the surge tank is spaced apart in a direction in which the extension extends. Is arranged at a predetermined position.

According to the present invention, a swirl flow is formed in the swirl flow forming unit, and a portion having the lowest pressure is formed in the swirl flow forming unit using the swirl flow. Then, the end of the exhaust gas introduction pipe was arranged at a position where the pressure was lowest.
As a result, the introduction of exhaust gas into the intake air can be promoted without using a turbocharger, regardless of the level of engine load, and the reduction of nitrogen oxides (NOx) in exhaust gas and fuel efficiency (thermal efficiency) can be promoted. ) Is advantageous.
Further , according to the present invention, since the pressure at a low pressure portion formed in the swirl flow forming portion can be further reduced by increasing the flow velocity of the swirl flow, the introduction of exhaust gas into the intake air can be further promoted. This is more advantageous in reducing nitrogen oxides (NOx) in exhaust gas and improving fuel efficiency (thermal efficiency).
Further , according to the present invention, the introduction of exhaust gas into the intake air can be further promoted with a simple configuration, which is more advantageous in reducing nitrogen oxides (NOx) in the exhaust gas and improving fuel efficiency (thermal efficiency). .
Further , according to the present invention, the exhaust gas introduction pipe does not interfere with the swirling flow, and the intake air mixed with the exhaust gas is smoothly introduced into the intake passage.
Further , according to the present invention, a swirl flow can be reliably generated with a simple configuration, a low-pressure portion can be reliably formed in the swirl flow forming portion, and the introduction of exhaust gas into the intake air can be promoted. This is more advantageous in reducing nitrogen oxides (NOx) and improving fuel efficiency (thermal efficiency).
Further , according to the present invention, the intake air mixed with the exhaust gas is smoothly introduced from the downstream portion into the tank interior space, and from the tank interior space into the branch pipe.

1 is a schematic configuration diagram illustrating a configuration of an intake device for an internal combustion engine according to the present embodiment. 1 is a perspective view of an intake device for an internal combustion engine according to the present embodiment. FIG. 3 is a sectional view taken along line AA of FIG. 2. FIG. 3 is a view on arrow B in FIG. 2.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the engine 10 includes an engine main body 12, an intake device 14, an exhaust device 16, and an exhaust gas recirculation device 18.

The engine main body 12 includes a cylinder block 1202 and a cylinder head 1204.
A plurality of cylinders (cylinder chambers) 20 for accommodating pistons are formed in the cylinder block 1202. In the present embodiment, three cylinders 20 are formed.
The cylinder head 1204 is provided with a combustion chamber, an intake port for supplying intake air to the combustion chamber, and an exhaust port for discharging exhaust gas from the combustion chamber, all of which are not shown, corresponding to each cylinder 20. .
Therefore, three combustion chambers, three intake ports, and three exhaust ports are provided.

The intake device 14 includes an intake pipe 22, a throttle valve (intake throttle) 24, a swirling flow forming section 26, an intake manifold 28, and an exhaust gas introduction pipe 30.
The upstream end of the intake pipe 22 is connected to an air cleaner (not shown), and the throttle valve 24 is connected to the downstream end of the intake pipe 22.
The throttle valve 24 adjusts the amount of intake air to the engine 10, and is composed of, for example, a butterfly valve including a valve shaft (not shown) and a valve plate fixed to the valve shaft.
The opening degree of the throttle valve 24 is adjusted by the engine ECU 42 controlling the amount of rotation when the butterfly plate rotates about the valve shaft as the rotation axis.

The intake manifold 28 includes a surge tank 32 and a plurality of branch pipes 34.
The surge tank 32 reduces intake pulsation and intake interference that may occur in each cylinder 20.
The plurality of branch pipes 34 branch from the surge tank 32 and are connected to respective intake ports. In FIG. 3, reference numeral 3402 denotes an opening of the branch pipe 34 that opens into the surge tank 32.
In the present embodiment, an intake passage that guides intake air to the combustion chamber includes an intake pipe 22, a throttle valve 24, a swirl flow forming section 26, an intake manifold 28, and an intake port.
The swirl flow forming section 26 is provided in the intake passage downstream of the throttle valve 24. Specifically, the swirl flow forming section 26 is disposed between the throttle valve 24 and the intake manifold 28.
The exhaust device 16 includes an exhaust manifold 36 connected to the exhaust port, and an exhaust pipe 38 connected to the exhaust manifold 36.
The exhaust gas recirculation device 18 recirculates exhaust gas extracted from the exhaust pipe 38 to the swirling flow forming section 26 into the intake passage.
The exhaust gas recirculation device 18 is configured to include an exhaust gas introduction pipe 30 and an exhaust gas valve 40.
The exhaust gas introduction pipe 30 connects the exhaust pipe 38 and the swirling flow forming section 26 to recirculate the exhaust gas. In other words, the exhaust gas introduction pipe 30 introduces exhaust gas into the intake passage.
The exhaust gas valve 40 is provided in the exhaust gas introduction pipe 30 and adjusts the recirculation amount of the exhaust gas. The opening degree of the exhaust gas valve 40 is adjusted by the engine ECU 42.

Next, the swirling flow forming unit 26 will be described in detail.
As shown in FIGS. 2, 3, and 4, the swirling flow forming section 26 is configured to include an upstream section 44 and a downstream section 46. In the present embodiment, the upstream section 44 and the downstream section 46 are connected to each other. A housing 48 is provided.
The upstream portion 44 is a portion where a swirling flow F is formed by intake air from the throttle valve 24.
In the present embodiment, the upstream portion 44 includes a cylindrical portion 4402 and an upstream pipe 4404 connected to the downstream end of the throttle valve 24 and connected tangentially to the cylindrical portion 4402. In FIG. 3, reference numeral 4406 denotes an opening of the upstream pipe 4404 that opens into the cylindrical portion 4402.
Therefore, the intake air introduced into the cylindrical portion 4402 from the upstream pipe 4404 becomes a swirling flow F inside the cylindrical portion 4402.
Here, the central axis of the cylindrical portion 4402, that is, the central axis of the swirl flow F is disposed so as to be parallel to the direction in which the valve axis of the throttle valve 24 extends, and the valve plate of the throttle valve 24 is in the same direction as the swirl flow F. It is desirable to increase the charging efficiency of the intake air and to promptly introduce the exhaust gas as described later.
The downstream portion 46 is configured to include a reduced diameter portion 4602 and a downstream pipe 4604.
As shown in FIG. 3, the reduced diameter portion 4602 is a portion where the outer diameter of the swirling flow F is gradually reduced as the distance from the upstream portion 44 increases, and the inner diameter and the outer diameter of the housing 48 constituting the reduced diameter portion 4602 are reduced. Are formed such that the diameter gradually decreases as the distance from the upstream portion 44 increases.
That is, the swirl flow forming section 26 has an upstream portion 44 that forms a swirl flow of the intake air and a downstream portion 46 having a smaller diameter than the upstream portion 44. In other words, the swirl flow forming section 26 is formed such that the diameter on the downstream side of the intake passage is smaller than the diameter on the upstream side of the intake passage.
The downstream pipe 4604 guides the swirling flow F reduced in diameter by the reduced diameter portion 4602 to the surge tank 32. The inner diameter and the outer diameter of the housing 48 constituting the downstream pipe 4604 are each formed to have uniform dimensions. I have.
The end of the downstream pipe 4604 is connected to the surge tank 32.

In the present embodiment, the cylindrical portion 4402, the reduced diameter portion 4602, and the downstream pipe 4604 are arranged coaxially, that is, arranged on the central axis 4610 of the downstream portion 46.
The exhaust gas introduction pipe 30 is inserted into the housing 48 from the cylindrical portion 4402 along the central axis 4610, and the end 3002 of the exhaust gas introduction pipe 30 to which the exhaust gas is supplied is reduced in diameter apart from the cylindrical portion 4402. The section 4602 or the center of the cross section of the downstream pipe 4604 is arranged. That is, the end portion 3002 of the exhaust gas introduction pipe 30 is arranged in the downstream portion 46, and is configured so that the exhaust gas is introduced into the radial center of the swirl flow forming portion 26.
A tank space 3202 inside the surge tank 32 extends along an extension of the center axis 4610, and a portion where the plurality of branch pipes 34 branch off from the surge tank 32 is located at the center axis 4610. They are arranged at intervals in the direction in which the extension lines extend.

Next, the operation and effect will be described.
When the engine 10 is operated in a state where the throttle valve 24 is opened at a predetermined opening by the engine ECU 42, the intake air flows from the intake pipe 22 through the throttle valve 24 to the upstream portion as shown in FIGS. Forty-four upstream pipes 4404 are introduced.
The intake air introduced into the upstream pipe 4404 is smoothly guided into the inside of the cylindrical portion 4402 along the tangential direction of the cylindrical portion 4402, and becomes a swirling flow F flowing along the inner peripheral surface of the cylindrical portion 4402.
The intake air having the swirling flow F flows toward the downstream pipe 4604 from the cylindrical portion 4402 through the reduced diameter portion 4602 while swirling.
In this case, the outer diameter of the swirling flow F gradually decreases as it approaches the downstream pipe 4604 by swirling along the reduced diameter portion 4602.
When the outer diameter of the swirl flow F is constant without change, the energy of the swirl flow F decreases as the swirl flow F approaches the downstream pipe 4604. Therefore, the flow velocity of the swirl flow F decreases as the swirl flow F approaches the downstream pipe 4604. I do.
On the other hand, in the present embodiment, the inner diameter of the reduced diameter portion 4602 gradually decreases, and the outer diameter of the swirling flow F gradually decreases. In this state, it reaches the downstream pipe 4604 and is guided from the downstream pipe 4604 to the tank space 3202 of the surge tank 32.

On the other hand, when the exhaust gas valve 40 is opened at a predetermined opening by the engine ECU 42, the exhaust gas flows from the exhaust pipe 38 through the exhaust gas introduction pipe 30 and the exhaust gas valve 40 to the end 3002 of the exhaust gas introduction pipe 30. Supplied to
The end 3002 of the exhaust gas introduction pipe 30 is located at the center of the cross section of the downstream pipe 4604 or at the center of the swirl flow F because the end 3002 is located at the reduced diameter section 4602 away from the cylindrical section 4402 or at the center of the cross section of the downstream pipe 4604. .
The pressure of the swirling flow F decreases from the outside to the inside in the radial direction, and the pressure decreases as the flow velocity of the swirling flow F increases.
Therefore, the end portion 3002 of the exhaust gas introduction pipe 30 is located at a position in the housing 48 where the pressure is the lowest.
As a result, the exhaust gas supplied to the exhaust gas introduction pipe 30 is guided to the portion of the housing 48 where the pressure is the lowest, so that the introduction of the exhaust gas to the intake is promoted.

For example, even when the engine 10 is under a low load, that is, when the opening of the throttle valve 24 is small and the amount of intake air is small, the pressure in the housing 48 near the end 3002 of the exhaust gas introduction pipe 30 is low. Because of the decrease, introduction of exhaust gas into the intake air is promoted.
Further, when the engine 10 is under a high load, that is, when the opening of the throttle valve 24 is fully opened or almost fully opened and the amount of intake air is large, the flow velocity of the swirling flow F becomes faster, so that exhaust gas is introduced. The pressure in the housing 48 near the end 3002 of the tube 30 is further reduced, and the introduction of exhaust gas into the intake air is further promoted.

Exhaust gas supplied from the end portion 3002 of the exhaust gas introduction pipe 30 to the center of the swirl flow F flows into the tank space 3202 from the reduced diameter portion 4602 or the downstream pipe 4604 while being mixed with the intake air that has become the swirl flow F. I do.
The intake and exhaust gases flowing into the tank space 3202 are further mixed by maintaining the swirling flow F in the tank space 3202, and are introduced from the tank space 3202 through the branch pipes 34 to the respective intake ports. .

  According to the present embodiment, the swirl flow forming unit 26 forms the swirl flow F, and the end 3002 of the exhaust gas introduction pipe 30 is disposed at the lowest pressure of the swirl flow forming unit 26. Without using a turbocharger, it is possible to promote the introduction of exhaust gas into the intake air regardless of the load of the engine 10, and to reduce nitrogen oxides (NOx) in the exhaust gas and improve fuel efficiency (thermal efficiency). This is advantageous in aiming.

Further, according to the present embodiment, in swirl flow forming section 26, the diameter on the downstream side of the intake passage is smaller than the diameter on the upstream side of the intake passage.
Therefore, by increasing the flow velocity of the swirl flow F, the pressure at a low pressure portion formed in the swirl flow forming unit 26 can be further reduced, so that the introduction of exhaust gas into the intake air can be further promoted, and This is more advantageous in reducing nitrogen oxides (NOx) and improving fuel efficiency (thermal efficiency).
Further, according to the present embodiment, the swirl flow forming section 26 is provided with the upstream portion 44 that forms the swirl flow F of the intake air and the downstream portion 46 that is smaller in diameter than the upstream portion 44. The part 3002 is arranged in the downstream part 46.
Therefore, the introduction of the exhaust gas into the intake air can be further promoted by a simple configuration, which is more advantageous in reducing nitrogen oxides (NOx) in the exhaust gas and improving fuel efficiency (thermal efficiency).

Further, according to the present embodiment, exhaust gas introduction pipe 30 is arranged along center axis 4610 of downstream portion 46. More specifically, they are arranged side by side on the central axis of the cylindrical portion 4402, the reduced diameter portion 4602, and the downstream pipe 4604.
Therefore, the exhaust gas introduction pipe 30 can reliably form a low pressure portion in the swirl flow forming part 26 without the exhaust gas introduction pipe 30 obstructing the flow of the swirl flow F, and introduce the exhaust gas into the intake air. This is more advantageous in reducing nitrogen oxides (NOx) in exhaust gas and improving fuel efficiency (thermal efficiency).

Further, according to the present embodiment, since tank interior space 3202 extends along the extension of central axis 4610 of downstream portion 46, the intake air mixed with the exhaust gas smoothly flows into tank interior space 3202. Will be introduced.
Further, according to the present embodiment, since openings 3402 of branch pipes 34 are arranged at intervals in the direction in which the extension of central axis 4610 extends, the intake air mixed with the exhaust gas is filled in tank space 3202. Through the branch pipe 34 smoothly.

  Further, according to the present embodiment, the upstream portion 44 that forms the swirl flow F is configured to include the cylindrical portion 4402 and the upstream pipe 4404, and the downstream portion 46 that reduces the diameter of the swirl flow F is formed by the reduced diameter portion 4602. Since the configuration includes the downstream pipe 4604, the swirl flow F can be reliably generated by a simple configuration, and a low-pressure portion can be reliably formed in the swirl flow forming unit 26, thereby facilitating the introduction of exhaust gas into the intake air. This is more advantageous in reducing nitrogen oxides (NOx) in exhaust gas and improving fuel efficiency (thermal efficiency).

Further, the central axis of the cylindrical portion 4402 (the central axis of the swirl flow F) is arranged so as to be parallel to the direction in which the valve axis of the throttle valve 24 extends, and the valve plate of the throttle valve 24 is set in the same direction as the swirl flow F. The following effects are exhibited by opening.
That is, even in the case of a partial load, the intake air passing through the throttle valve 24 is introduced into the swirl flow forming section 26 along the flow of the swirl flow F. Therefore, the introduced intake air does not hinder the flow of the swirl flow F, and can maintain and form a large flow velocity and a large swirl radius of the swirl flow F. Therefore, the charging efficiency of the intake air can be further increased.
Further, in the case of introducing the exhaust gas, since the pressure of the swirl center where the exhaust gas is introduced is reduced by increasing the flow velocity of the swirling flow F, the exhaust gas can be quickly introduced.

  In addition, the upstream portion 44 that forms the swirling flow is configured without using the upstream pipe 4404, and the downstream portion 46 that reduces the diameter of the swirling flow F is configured without using the downstream tube 4604. However, if the upstream portion 44 and the downstream portion 46 are configured as in the embodiment, the swirling flow can be reliably formed by the simple configuration, and the low pressure is realized by the simple configuration. This is advantageous in reliably forming the location.

10. Engine (internal combustion engine)
12 Engine body 14 Intake device 18 Exhaust gas recirculation device 22 Intake pipe 24 Throttle valve 26 Swirling flow forming part 28 Intake manifold 30 Exhaust gas introduction pipe 32 Surge tank 3202 Inside tank space 34 Branch pipe 44 Upstream section 4402 Cylindrical section 4404 Upstream pipe 46 Downstream section 4602 Reduced diameter section 4604 Downstream pipe 4610 Central axis 48 Housing F Swirling flow

Claims (4)

An intake passage connected to the internal combustion engine,
An exhaust gas introduction pipe that introduces exhaust gas discharged from the internal combustion engine into the intake passage;
An intake device for an internal combustion engine comprising:
Comprising a swirl flow forming member which forms a swirling flow by the intake provided in the intake passage,
The end of the exhaust gas inlet pipe, the exhaust gas is introduced into the radial center portion of the swirling flow forming portion,
The swirling flow forming portion has an upstream portion that forms a swirling flow of the intake air and a downstream portion having a smaller diameter than the upstream portion,
An end of the exhaust gas introduction pipe is disposed at the downstream portion,
A throttle valve provided in the intake passage,
The upstream portion includes a cylindrical portion, and an upstream pipe connected to the throttle valve and tangentially connected to the cylindrical portion,
The downstream portion includes a reduced diameter portion that gradually reduces the outer diameter of the swirling flow as the distance from the cylindrical portion increases, and guides the reduced diameter swirling flow connected to the reduced diameter portion to a downstream side of the intake passage. Comprising a downstream pipe,
An intake device for an internal combustion engine, characterized in that:   2. The intake device for an internal combustion engine according to claim 1, wherein the swirl flow forming portion has a diameter on the downstream side of the intake passage smaller than a diameter on the upstream side of the intake passage. 3. The exhaust gas introduction pipe is disposed along an axis of the swirl flow forming unit.
3. The intake device for an internal combustion engine according to claim 1, wherein The intake passage includes an intake manifold,
The intake manifold has a surge tank, and a plurality of branch pipes branched from the surge tank and connected to an intake port of the internal combustion engine,
The tank interior space inside the surge tank extends along an extension of the axis of the downstream portion,
Location where the plurality of branch pipes branched from the surge tank, according to any one of the internal combustion engine of claims 1 to 3, characterized in that it is spaced in the extending direction of the extension line Intake device.

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