JP2014092111A - Waste gate structure of turbocharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste gate structure of a turbocharger that promotes temperature rise of an exhaust gas cleaning device and contact of exhaust gas and catalyst by mixing (unifying) exhaust gas, at a period, in which there are few exhaust gas emission amounts, right after internal combustion engine cold state start, and promotes exhaust gas cleaning by quickening catalyst activity.SOLUTION: In a waste gate structure of a turbocharger, a strip-shaped projection 52, which originates a swirl flow in the same direction as a swirl flow formed on the downstream side of an exhaust turbine, is provided in the periphery of a waste gate opening part 53. The waste gate structure makes a waste gate opened at the cold state of an internal combustion engine, and passes exhaust gas through the waste gate.

Description

  The present invention relates to an exhaust gas purification apparatus for an internal combustion engine with a supercharger in which an exhaust turbine of a turbocharger and an exhaust gas purification apparatus are disposed in an exhaust passage of the internal combustion engine.

In general, a turbocharger such as a turbocharger using exhaust gas is frequently used to improve the output and fuel consumption of an internal combustion engine.
The turbocharger drives an exhaust turbine with exhaust gas flowing through an exhaust passage, and supercharges air with a compressor coaxially connected to the exhaust turbine to increase the output of the internal combustion engine.
An exhaust gas purification device that purifies the exhaust gas is disposed downstream of the exhaust gas passage of the exhaust turbine.
In the exhaust emission control device, a catalyst support having a honeycomb structure having a larger cross-sectional area in the direction perpendicular to the axis of the exhaust gas passage is housed in a cylindrical casing.

Thus, when the exhaust turbine of the turbocharger is provided in the exhaust passage of the internal combustion engine, the exhaust gas flow turns into a swirl flow that swirls around the axis of the exhaust passage in the exhaust passage downstream of the exhaust turbine.
The swirling flow of the exhaust gas flows into the catalyst carrier in a state where the velocity in the tangential direction or the inclination direction is large with respect to the front end face of the cylindrical catalyst carrier.
This makes it difficult for exhaust gas to flow into each cell of the catalyst carrier.

According to Patent Document 1, there is a technique in which a reverse swirl flow generating means for generating a reverse swirl flow that cancels a swirl flow formed on the downstream side of the exhaust turbine is provided at the exit of the exhaust gate of the turbocharger in the exhaust passage. Proposed.
According to the proposal, when the exhaust gas flows out from the exhaust turbine, the swirl flow of the exhaust gas formed on the downstream side is offset by the reverse swirl flow of the exhaust gas generated by the reverse swirl flow generating means provided at the outlet of the wastegate. Therefore, when flowing into the exhaust purification device, the flow is substantially parallel to the axial direction of the exhaust passage, so that the exhaust gas easily enters the exhaust purification device.

JP 2009-275527 A

However, according to Patent Document 1, the internal combustion engine operating region in which the wastegate is opened is performed when it is not desired to increase the boost pressure any more.
In this case, the exhaust gas flow rate is very large in the region where the supercharging pressure is controlled, and the temperature is high.
In such a state, the catalyst carrier temperature of the exhaust purification device is sufficiently high, and the exhaust gas purification action is performed without any problem.
However, when the internal combustion engine is started, that is, immediately after the cold start, the catalyst temperature of the exhaust purification device is low, and the exhaust gas purification action in the exhaust purification device is not sufficiently performed.
Therefore, although it is necessary to raise catalyst temperature at an early stage, Patent Document 1 does not disclose a technical disclosure regarding early catalyst activity immediately after cold start.

  The present invention has been made in view of the above-described problems of the prior art, and at the time when the exhaust gas emission amount is small immediately after the cold start of the internal combustion engine, the temperature of the exhaust purification device is increased and the exhaust gas is mixed (homogenized). The purpose of the present invention is to provide a turbocharger wastegate structure that promotes contact between exhaust gas and catalyst and promotes exhaust gas purification by accelerating catalyst activity.

In order to achieve the above object, according to the present invention, in the wastegate structure of the turbocharger in which the exhaust turbine of the turbocharger and the exhaust purification device are disposed in the exhaust passage of the internal combustion engine,
A swirling flow generating means for generating a swirling flow in the same direction as the swirling flow of the exhaust gas discharged from the exhaust turbine is provided around the waste gate opening and downstream of the waste gate opening. A wastegate structure for a turbocharger is provided in which the wastegate opening is opened during cooling so that exhaust gas passes through the wastegate opening.

  In the present invention, it is preferable that the swirl flow generating means has a base end portion located on an outer peripheral edge of the waste gate opening, and is provided with a strip-shaped protrusion extending in an arc shape in the exhaust passage. It is good to be.

With such a configuration, the temperature of the exhaust gas decreases due to expansion when the exhaust turbine is driven.
Therefore, forcibly opening the wastegate when the internal combustion engine is cold prevents the exhaust gas temperature from being lowered by driving the exhaust turbine, and introduces exhaust gas that maintains a high temperature into the exhaust gas purification device, thereby accelerating the catalyst activity. This makes it possible to promote exhaust gas purification at an early stage of starting the internal combustion engine.
Further, the swirl flow promotes the mixing of the exhaust gas, and the purification with the catalyst can be performed efficiently.

  Preferably, in the present invention, the swirl flow generating means includes a lid member that opens and closes the waste gate opening and opens and closes to the exhaust passage side, and is fixed to the lid member, and has an outer peripheral portion with respect to the waste gate opening. It is good to provide the tubular guide member which slidably fits, and the surrounding wall of this guide member is good to provide a notch part in the same direction as the said swirl flow.

  With such a configuration, the cover member that closes the wastegate opening is provided with a notch in the swiveling direction, so that the cost can be suppressed relative to the swirling flow generating means provided in the turbocharger body.

  Preferably, in the present invention, the wastegate opening is arranged eccentrically with respect to a cylindrical center of the exhaust passage provided with the wastegate opening, and the notch is the same as the exhaust gas swirl flow. It should be open in the direction.

  With such a configuration, the wastegate opening is eccentric with respect to the cylindrical wastegate passage, that is, the exhaust gas ejected from the notch is ejected along the inner peripheral surface of the exhaust passage. Will be strengthened.

  According to the present invention, the temperature of the exhaust emission control device is increased and the exhaust gas is mixed (homogenized) at a time when the exhaust gas emission amount is small immediately after the internal combustion engine cold start, thereby promoting the contact between the exhaust gas and the catalyst. It is possible to provide a turbocharger wastegate structure that promotes exhaust gas purification through early activation.

(A) is a schematic explanatory view in which a turbocharger and an exhaust purification device are arranged in an exhaust passage of an internal combustion engine in an embodiment of the present invention, and (B) shows an enlargement of a Z portion of (A). 1st Example of the swirl | vortex flow generation means in A arrow view of FIG. 1 (B) is shown. The 2nd Embodiment of the swirl | vortex flow generation means of this invention is shown, (A) is a wastegate obstruction | occlusion state figure, (B) is a wastegate open | release state figure, (C) shows the Z arrow view of (A). The BB cross section of FIG. 1 shows explanatory drawing of exhaust gas swirl in the second embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to specific examples unless otherwise specifically described. Only.

(First embodiment)
FIG. 1A is a schematic explanatory diagram in which a turbocharger 1 and an exhaust purification device 2 are disposed in an exhaust passage of an internal combustion engine (not shown).
The exhaust gas discharged from the exhaust manifold 15 of the internal combustion engine (not shown) drives the turbocharger 1 and is introduced into the exhaust purification device 2 by the exhaust pipe 6 which is an exhaust passage, and is rendered harmless by the exhaust purification device 2. (Purified) and released into the atmosphere.
On the other hand, the air taken in by the air cleaner 3 by driving the turbocharger 1 is compressed and supplied to the internal combustion engine via the inlet manifold 31.

  The turbocharger 1 is coaxially connected to the exhaust turbine 12 that is rotationally driven by exhaust gas discharged from an exhaust manifold of the internal combustion engine, and compresses the air introduced from the air cleaner 3 so as to compress the internal combustion engine. A compressor 13 for supplying compressed air to the inlet manifold 31, a housing 11 containing the compressor 13, the exhaust turbine 12, and a rotating shaft 14 connecting them, and an exhaust gas flow path upstream of the exhaust turbine 12 of the housing 11. And a wastegate 5 that bypasses the exhaust turbine 12 with a part of the exhaust gas when the supercharging pressure of the compressor 13 exceeds a specified pressure.

FIG. 1B is an enlarged view of a Z portion in FIG. 1A and shows an exhaust gas discharge portion of the wastegate 5.
The wastegate 5 is an exhaust gas flow path formed in the housing 11 and is disposed on the upstream side of the exhaust turbine 12, and opens and closes the wastegate opening 53 for bypassing the exhaust gas, and the wastegate opening 53. A wastegate valve 51 as a lid member, an electromagnetic actuator 54 for opening and closing the wastegate valve 51, a controller 55 for controlling the opening and closing operation of the electromagnetic actuator 54, and an air pressure sensor 55g for detecting the air pressure taken in by the air cleaner 3 A first wiring 55a for inputting the detected pressure of the air pressure sensor 55g to the controller 55, a boost pressure sensor 55f for detecting the boost pressure by the compressor 13, and the detected pressure of the boost pressure sensor 55f to the controller 55. Input second wiring 55b, water temperature sensor for detecting the cooling water temperature of the internal combustion engine 55d, a third wiring 55c for inputting the water temperature detected by the water temperature sensor 55d to the controller 55, a fourth wiring 55h for supplying electric power for operating the electromagnetic actuator 54, and the waste gate valve 51 by the operation of the magnetic actuator 54. A link member 55d for driving the motor.

The operation of the wastegate 5 in the general state will be described.
When the internal combustion engine operates, exhaust gas is discharged from the exhaust manifold 15. The amount of exhaust gas to be discharged varies depending on the operating condition of the internal combustion engine. When the load is high, the exhaust gas discharge amount increases, and the rotational force and the rotational speed of the exhaust turbine 12 increase.
Accordingly, the supercharging pressure of the compressor 13 that is coaxially connected to the exhaust turbine 12 increases.
However, the supercharging pressure of the internal combustion engine does not perform supercharging exceeding a specified value in order to maintain the durability of the internal combustion engine.
The wastegate 5 operates the actuator 54 when the supercharging pressure by the compressor 13 exceeds a specified value, separates the wastegate valve 51 from the wastegate opening 53, and causes a part of the exhaust gas to flow to the exhaust pipe 6 side. The exhaust turbine 12 is bypassed.

  By bypassing the exhaust gas to the exhaust turbine 12, the supercharging pressure of the compressor 13 decreases. When the supercharging pressure reaches a specified value, the wastegate 5 closes the wastegate opening 53 to maintain normal operation of the internal combustion engine.

However, when the internal combustion engine is started, that is, when the internal combustion engine is in a cold state, the exhaust purification device 2 is also at substantially the same temperature as the atmospheric temperature.
That is, the temperature detected by the water temperature sensor 55d is detected lower than a specified value.
On the other hand, the exhaust gas purification catalyst disposed in the exhaust gas purification device 2 does not perform a sufficient purification action unless the temperature exceeds a certain level.
In such a state, it is necessary to quickly raise the temperature of the exhaust gas purification catalyst.
Immediately after the internal combustion engine is started, the amount of exhaust gas is small, so the wastegate 5 is forcibly actuated to cause a part of the exhaust gas to flow to the exhaust pipe 6 side and promote the temperature rise of the exhaust gas purification catalyst.
After the exhaust gas drives the exhaust turbine 12, the temperature decreases due to the expansion of the exhaust gas, and in order to prevent the heat of the exhaust gas from being absorbed by the exhaust turbine 12, the wastegate 12 is opened so that the exhaust gas is discharged from the exhaust turbine 12. By bypassing, the temperature of the exhaust gas purification catalyst is increased.

However, in the exhaust purification device 2, a honeycomb-shaped catalyst carrier having a large cross-sectional area in a direction perpendicular to the axis of the exhaust pipe 6 is accommodated in a cylindrical casing.
Therefore, when the internal combustion engine is in a cold state and the exhaust gas emission amount is being controlled with a small amount of exhaust gas, the exhaust gas in the exhaust pipe 6 is introduced into the catalyst while swirling. Confirmed by experimental results.
This is because, even during the temperature rise control of the catalyst, the exhaust gas is swirled and introduced into the catalyst, thereby improving the area utilization rate (contact area between the exhaust gas and the catalyst) at the catalyst inlet end surface and the exhaust gas. It is analyzed that mixing is promoted and the reaction at the catalyst becomes high.

FIG. 2 is a cross-sectional view taken along the line B-B in FIG.
In the present embodiment, the wastegate 5 is forcibly opened during a cold operation of the internal combustion engine (when the temperature detected by the water temperature sensor 55d of the internal combustion engine is equal to or lower than a predetermined value), and a swirling flow is generated at the exhaust gas outlet of the wastegate 5. A plurality of strip-shaped protrusions 52 extending in an arc shape as means are provided.
The protrusion 52 is provided on a wall surface 53 a that is radially expanded from the outer peripheral edge of the wall surface on which the wastegate opening 53 is formed on the exhaust pipe 6 side.
The protrusion 52 has a proximal end portion positioned on the outer peripheral edge of the wastegate opening 53 and a distal end portion formed in an arc shape outward in the radial direction.
The arc-shaped direction is provided so that the exhaust gas discharged from the wastegate opening 53 flows in the same direction as the exhaust gas swirling flow discharged from the exhaust gas outlet 17 of the exhaust turbine 12.

  With such a structure, the wastegate 5 is opened during the cold operation immediately after starting the internal combustion engine with a small amount of exhaust gas emission. The opening of the wastegate 5 introduces high-temperature exhaust gas into the catalyst and swirls the exhaust gas to mix HC, nitrogen oxides and other harmful substances present in the exhaust gas, thereby homogenizing the harmful substances. . Homogenization of toxic substances is promoted by improving the area utilization rate (contact area between exhaust gas and catalyst) at the catalyst inlet end face and promoting the purification of toxic substances in the exhaust gas. The exhaust gas purification effect can be obtained.

(Second Embodiment)
This embodiment is the same as the first embodiment except that the structure of the swirling flow generating means is different.
Therefore, descriptions other than the swirl flow generating means are omitted, and the same components are denoted by the same reference numerals and description thereof is omitted.

FIG. 3A is a waste gate closed state diagram, FIG. 3B is a waste gate released state diagram, and FIG. 3C is a Z arrow view of FIG.
The bypass opening / closing portion of the wastegate 7 includes a wastegate opening 73 through which exhaust gas passes and a wastegate valve 71 that closes or releases the wastegate opening 73.
The wastegate opening 73 of the wastegate 7 is disposed upstream of the exhaust gas passage of the exhaust turbine 12.
The wastegate opening 73 is formed in a direction perpendicular to the housing 11 of the exhaust turbine 12, and a conical first seal surface 11a is formed on the outer side of the housing 11. The BB cross section of FIG. 1 shows explanatory drawing of exhaust gas swirl in the second embodiment.
FIG. 4 is a cross-sectional view taken along the line BB in FIG. 1B, illustrating an example of exhaust gas swirling in this embodiment. An upstream view of the wastegate opening 73 from the downstream side of the exhaust passage 6 is shown.
The wastegate opening 73 has a cylindrical outer periphery of the wall surface 11 on the exhaust pipe 6 side where the wastegate opening 73 is provided, and a second center CP2 that is the center (axial center) of the cylindrical shape. On the other hand, the first center CP1 that is the opening center of the wastegate opening 73 is disposed at an offset position.

On the other hand, the wastegate valve 71 has a truncated cone shape that is a lid member having a conical second seal surface 71 a facing the conical first seal surface 11 a of the wastegate opening 73.
A guide member 72 slidable with respect to the inner peripheral surface of the wastegate opening 73 is fixed to the top of the truncated cone shape of the wastegate valve 71.
As shown in FIG. 3C, the guide member 72 has a hollow cylindrical shape, and a part of the hollow cylindrical wall surface is in the same direction as the cylindrical peripheral wall surface of the exhaust pipe 6 and is exhausted from the exhaust turbine. It has a notch 72a that opens in the same direction as the swirling flow of the exhaust gas discharged from the outlet 17.
The exhaust gas from the notch 72a is discharged in a state along the cylindrical peripheral wall surface of the exhaust pipe 6 to form a swirl flow, and swirls in the same direction as the swirl flow of the exhaust gas discharged from the exhaust gas outlet 17 of the exhaust turbine. It has become.

The opening and closing of the waste gate valve 71 will be described with reference to FIG.
FIG. 3A shows a situation where the wastegate opening 73 is closed by the wastegate valve 71.
In the wastegate valve 71, the second seal surface 71 a of the wastegate valve 71 is pressed against the first seal surface 11 a by the electromagnetic actuator 54, and the guide member 72 is fitted in the wastegate opening 73.
Therefore, there is no outflow of exhaust gas from the wastegate opening 73 to the exhaust pipe 6 side.

Next, the case where the wastegate valve 71 is operated will be described.
When exhaust gas is allowed to flow from the wastegate opening 73 to the exhaust pipe 6, the state shown in FIG. That is, the wastegate valve 71 is driven in the opening direction (rightward in FIG. 3B) by the electromagnetic actuator 54.
The second seal surface 71a of the waste gate valve 71 is separated from the first seal surface 11a, and the guide member 72 is also driven in the opening direction.
The notch 72a of the guide member 72 is in a state where it communicates with a separated portion (gap) between the second seal surface 71a and the first seal surface 11a.
The exhaust gas passes through the hollow cylindrical portion and the cutout portion 72a of the guide member 72, and flows from the separated portion between the second seal surface 71a and the first seal surface 11a to the exhaust pipe 6 side.

By adopting such a structure, the opening center CP1 of the wastegate opening 73 is offset with respect to the center CP2 of the circular wall portion where the wastegate opening 73 is provided. The notch 72 a of the member 72 is opened in a direction along the cylindrical peripheral wall surface of the exhaust pipe 6.
Therefore, as shown in FIG. 4, the exhaust gas exiting the notch 72a is given a swirl force by the cylindrical peripheral wall surface of the exhaust pipe 6, and the swirl flow of the exhaust gas discharged from the exhaust gas outlet 17 of the exhaust turbine. Since they are arranged in the same direction, the swirl flow of the exhaust gas is accelerated even when the exhaust gas emission amount during the warm-up operation is small.
As a result, the exhaust gas is improved in the area utilization rate (contact area between the exhaust gas and the catalyst) at the catalyst inlet end face, the mixing of the exhaust gas is promoted, the reaction amount in the catalyst is increased, and the early exhaust gas purification effect is achieved. Can get.

  The present invention can be applied to an internal combustion engine with a supercharger in which a turbocharger and an exhaust purification device are arranged in an exhaust passage of the internal combustion engine.

1 Turbocharger 2 Exhaust purification device 5, 7 Westgate 6 Exhaust pipe (exhaust passage)
DESCRIPTION OF SYMBOLS 11 Housing 11a 1st sealing surface 12 Exhaust turbine 13 Compressor 17 Exhaust gas exit 51, 71 Wastegate valve (lid body)
52 Projection 53, 73 Wastegate opening 53a Outer peripheral wall surface 54 Actuator 55 Controller 71a Second seal surface 72 Guide member 72a Notch

Claims (4)

In the turbocharger wastegate structure in which the exhaust turbine of the turbocharger and the exhaust gas purification device are disposed in the exhaust passage of the internal combustion engine,
A swirling flow generating means for generating a swirling flow in the same direction as the swirling flow of the exhaust gas discharged from the exhaust turbine is provided around the waste gate opening and downstream of the waste gate opening. A wastegate structure for a turbocharger, wherein the wastegate opening is opened during cooling so that exhaust gas passes through the wastegate opening.   The swirl flow generating means is characterized in that a base end portion is located at an outer peripheral edge of the waste gate opening, and a strip-shaped protrusion extending in an arc shape is provided in the exhaust passage. The wastegate structure of the turbocharger according to 1.   The swirl flow generating means is fixed to the lid member that opens and closes the wastegate opening and opens and closes to the exhaust passage side, and an outer peripheral portion is slidably fitted to the wastegate opening. 3. The turbocharger wastegate structure according to claim 1, further comprising a tubular guide member, wherein a peripheral wall of the guide member has a notch in the same direction as the swirling flow. 4.   The wastegate opening is arranged eccentrically with respect to the cylindrical center of the exhaust passage where the wastegate opening is provided, and the notch is opened in the same direction as the exhaust gas swirl flow. The wastegate structure of a turbocharger according to claim 3,

Images