JP6489266B2 - Valve unit - Google Patents

Description

  The present invention relates to a valve unit that constitutes a low-pressure EGR device.

Conventionally, a part of low-pressure exhaust gas (hereinafter sometimes referred to as EGR gas) after passing through a turbine in an engine intake / exhaust system having a turbocharger is recirculated to the flow of intake air and is led to a compressor. EGR devices are known.
The low-pressure EGR device includes an intake passage through which intake air flows and a low-pressure EGR passage through which EGR gas flows.
Further, the low pressure EGR device includes an intake throttle valve body (hereinafter sometimes referred to as a first valve body) that adjusts a negative pressure generated at a junction between the intake flow path and the low pressure EGR flow path, and a low pressure EGR flow path. A low pressure EGR adjusting valve body (hereinafter sometimes referred to as a second valve body).

Here, a configuration of a valve unit in which the first valve body and the second valve body are arranged close to each other for the purpose of reducing the number of connected parts and the number of parts is well known.
The valve unit includes a passage forming member having a first passage that forms part of an intake passage and a second passage that forms part of a low-pressure EGR passage, and the first valve body is accommodated in the first passage. And the 2nd valve body is accommodated in the 2nd channel | path (for example, refer patent document 1).

In recent years, in order to meet the demand for downsizing of the valve unit, it has been considered to bring the first valve body closer to the second passage and to delete a portion upstream of the rotation region of the first valve body in the passage forming member. Yes.
However, in this case, the first valve body approaches the second passage through which the EGR gas flows, and the possibility that the EGR gas hits the first valve body is increased.

However, when the intake air recirculates EGR gas in a low temperature range where the temperature is low, the first valve body exposed to the intake air is at a low temperature. The following problems are concerned.
That is, when the EGR gas hits the low temperature first valve body, the water vapor in the EGR gas is cooled to cause condensation, and water droplets are generated on the first valve body. The generated water droplets are the turbocharger compressor. There is a risk of eroding.

JP 2013-096286 A

  The present invention has been made in view of the above problems, and an object of the present invention is to suppress the generation of water droplets on the first valve body even in a case where the temperature of the intake air is low in the valve unit. This is to suppress erosion caused by water droplets in the compressor.

The valve unit of the present invention is assembled in an intake / exhaust system that supercharges intake air taken into the engine by a turbocharger.
The low-pressure EGR gas, which is low-pressure exhaust gas that has passed through the turbine of the turbocharger, is recirculated to the flow of intake air and is used to guide it to the compressor of the turbocharger.

The valve unit includes a passage forming member, a first valve body, and a second valve body, which will be described in detail below.
The passage forming member has a first passage through which intake air flows and a second passage connected to the first passage. The low pressure EGR gas is introduced into the second passage and merges with the intake air flowing through the first passage. Let
The first valve body is accommodated in the first passage and is rotationally driven to restrict the flow of intake air.
The second valve body is accommodated in the second passage and is rotationally driven to restrict the flow of the low pressure EGR gas.

Here, the second passage is provided as a cylindrical space whose axis is a straight line.
Then, let us consider a passing region through which the second valve body passes when the second valve body in a state where the second passage is fully closed is moved toward the first passage in the axial direction of the second passage. And a part or all of the rotation area | region of a 1st valve body exists in a passage area | region.
Here, the first valve body has a plate shape in which the thickness direction does not correspond to the flow direction of the intake air in the rotation region, and the low pressure EGR gas flowing into the first passage from the second passage is included in the first valve body. The downstream guide means is provided to promote the flow of the gas toward the downstream side of the flow in the first passage.
Further, the downstream side guiding means is a hole penetrating the first valve body whose axial direction is the flow direction of the intake air at a predetermined position in the rotation region.

Thereby, in a valve unit, generation | occurrence | production of the water droplet to a 1st valve body can be suppressed by suppressing arrival of EGR gas to a 1st valve body.
For this reason, it can suppress that the compressor of a turbocharger is eroded by the water droplet.
In addition, the hole is provided obliquely with respect to the thickness direction of the first valve body, and when the hole having the same diameter is provided, the length in the axial direction is larger than the through hole penetrating in the thickness direction. Since it is long, it can contribute to weight reduction of a 1st valve body.

1 is a schematic view of an engine intake / exhaust system having a turbocharger (Reference Example, Example 1). It is the schematic of a valve unit (reference example). It is a configuration explanatory view of the valve unit (reference example). (A) The top view of a 1st valve body, (b) It is the schematic of a valve unit (Example 1). It is a top view of the 1st valve body (modification)

  Hereinafter, modes for carrying out the invention will be described based on examples.

[Reference example]
An engine intake / exhaust system 2 including a valve unit 1 of a reference example will be described with reference to FIG.
The engine intake / exhaust system 2 is an intake / exhaust system that supercharges intake air drawn into the engine 3 to the engine 3 by the turbocharger 4, and is provided with a high pressure EGR device 5 and a low pressure EGR device 6.
The engine 3 shown in this embodiment is a diesel engine for driving a vehicle, and includes an intake passage 7 that guides intake air to a cylinder and an exhaust passage 8 that exhausts exhaust gas generated in the cylinder into the atmosphere. Prepare.

The high pressure EGR device 5 includes an exhaust passage 8 in a range where high negative pressure is generated on the inside of the exhaust passage 8 where a high exhaust pressure is generated on the exhaust upstream side of the DPF 9 and an intake downstream side of the throttle valve 10. This is an exhaust gas recirculation device that is good at connecting the inside and returning a large amount of EGR gas to the engine 3.
The high-pressure EGR device 5 includes a high-pressure EGR flow path 12 that returns a part of the exhaust gas as EGR gas to the intake passage 7.
In the high pressure EGR device 5 shown in FIG. 1, the high pressure EGR flow path 12 has an exhaust flow path 8 side connected to an exhaust manifold and an intake flow path 7 side connected to a surge tank 13 of the intake manifold.

Further, the high pressure EGR device 1 shown in FIG. 1 includes a high pressure EGR adjustment valve body 15 that adjusts the flow rate of the EGR gas by adjusting the opening degree of the high pressure EGR passage 12 in the middle of the high pressure EGR passage 12. Switching between the high pressure EGR cooler 16 that cools the EGR gas returned to the intake flow path 7, the bypass 17 that bypasses the EGR gas returned to the intake flow path 7 from the high pressure EGR cooler 16, and the high pressure EGR cooler 16 and the bypass 17 And a switching valve 18 is provided.
FIG. 1 is a specific example, and the high-pressure EGR cooler 16, the bypass 17, and the switching valve 18 may not be mounted.

The low pressure EGR device 6 includes an exhaust passage 8 in a range where a low exhaust pressure is generated on the exhaust downstream side of the DPF 9 and an intake passage 7 in a range where a low intake negative pressure is generated on the intake upstream side of the throttle valve 10. This is an exhaust gas recirculation device that is good at returning a small amount of EGR gas to the engine 3 by connecting to the inside. And the low pressure EGR flow path 20 which returns a part of exhaust gas to the intake flow path 7 as EGR gas is provided.
More specifically, the low-pressure EGR flow path 20 is configured such that the exhaust flow path 8 side is downstream of the DPF 9 and the exhaust flow path 8 is led downstream of the DPF 9 so that a part of the exhaust gas that has passed through the turbine 21 and the DPF 9 of the turbocharger 4 is guided to the compressor 22 of the turbocharger 4. The exhaust passage 8 is connected to the intake passage 7 on the upstream side of the compressor 22 of the turbocharger 4.

  The low-pressure EGR device 6 includes a low-pressure EGR adjustment valve body (hereinafter referred to as a second valve body 25) that adjusts the flow rate of EGR gas by adjusting the opening degree of the low-pressure EGR flow path in the middle of the low-pressure EGR flow path 20. And a low-pressure EGR cooler 26 that cools the EGR gas returned to the intake passage 7.

In addition, the low pressure EGR device 6 has an intake throttle valve body (hereinafter, may be referred to as a first valve body 27) for generating an intake negative pressure at the junction of the intake flow path 7 and the low pressure EGR flow path 20. Is provided.
In addition, by generating the intake negative pressure by the first valve body 27, the differential pressure can be secured also in the low pressure EGR device 6, and a large amount of EGR gas can be recirculated to the engine 3 in the low pressure EGR device 6. It becomes like this.

  Further, the first valve body 27 is provided so as to open a part of the intake flow path 7 even when the intake flow path 7 is squeezed to the maximum. Specifically, even if the first valve body 27 is in a state where the intake passage 7 is squeezed to the maximum, the first valve body 27 is provided so as to open, for example, about 10% of the intake passage 7.

Here, the first valve body 27 and the second valve body 25 constitute the valve unit 1.
The valve unit 1 constitutes a low-pressure EGR device 6. As shown in FIG. 2, the valve unit 1 has a first passage 30 through which intake air flows and a second passage 31 connected to the first passage 30. A passage forming member 32 that introduces EGR gas into the second passage 31 and merges with the intake air flowing through the first passage 30 is provided.
The first passage forms part of the intake passage 7, and the second passage 31 forms part of the low-pressure EGR passage 20.

The first valve body 27 is a plate-like butterfly valve accommodated in the first passage 30, and is driven to rotate integrally with a first shaft 33 that is rotatably supported by the passage forming member 32, thereby Narrow down the flow.
The second valve body 25 is a plate-like butterfly valve housed in the second passage 31, and is rotated integrally with a second shaft 34 that is rotatably supported by the passage forming member 32, so that EGR gas Narrow down the flow.
The first shaft 33 and the second shaft 34 are arranged in parallel.

Here, the valve unit 1 includes one electric actuator 35 that rotationally drives the second valve body 25, and a link device 36 that rotationally drives the first valve body 27 by changing the output characteristics of the electric actuator 35. The first valve element 27 is rotationally driven by the output of the electric actuator 35 transmitted via the link device 36.
The link device 36 is provided with a characteristic converter that changes the output characteristic of the electric actuator 35 and transmits the change to the first valve element 27. The second valve element 25 is increased after the second valve element 25 exceeds a predetermined opening degree. The opening degree of the first valve body 27 is reduced in conjunction with the opening degree of the body 25 being increased.

  The electric actuator 35 includes an electric motor 38 (for example, a DC motor) that generates a rotation output by energization, and a speed reduction mechanism 39 (for example, a gear reduction device) that reduces the rotation output of the electric motor 38 and increases an output torque. Is a combination. Then, the second valve body 25 is rotationally driven by the output of the speed reduction mechanism 39 and the first valve body 27 is rotationally driven via the link device 36.

  The link device 36 is disposed outside the passage forming member 32, converts the rotation characteristic that is the output characteristic of the electric actuator 35, and drives the first valve body 27, and is integrated with the second valve body 25. And a follower arm 41 that rotates integrally with the first valve body 27.

The cam plate 40 has a plate shape and is formed of nylon resin or the like, which is a material having excellent wear resistance, and is fixedly disposed at a right angle to the second shaft 34.
The driven arm 41 also has a plate shape and is formed of nylon resin or the like, which is a material with excellent wear resistance. The driven arm 41 has a rotating end side spaced apart from the cam plate 40 by a predetermined gap. The first shaft 33 is fixedly disposed at a right angle so as to overlap with each other.

In the link device 36, the characteristic conversion unit that converts the output characteristic of the electric actuator 35 is provided at a position away from the rotation center of the driven arm 41 and the cam groove 43 provided at a position away from the rotation center of the cam plate 40. And an engaging portion 45 that fits into the cam groove 43.
The engaging portion 45 includes a cylindrical roller 45a that fits in the cam groove 43, and a shaft portion 45b that is fixed to the rotating end side of the driven arm 41 and rotatably supports the roller 45a.

The cam profile of the cam groove 43 that drives the engaging portion 45 is provided by connecting the cam groove 43 a for keeping the opening degree of the first valve body 27 and the cam groove 43 b that drives the first valve body 27.
The cam groove 43a is an arc groove having the same center as the rotation center of the cam plate 40, and the rotation range from the fully closed opening θ0 at which the second valve body 25 squeezes the second passage 31 to the maximum intermediate opening θ1. The opening of the first valve element 27 is provided to keep the maximum opening.

  The cam groove 43b is formed so as to continue to one end of the cam groove 43a, is a circular arc groove having a center different from the rotation center of the cam plate 40, and the second valve body 25 is at a predetermined intermediate position. The driven arm 41 is rotated in a rotation range from the opening degree θ1 to the maximum opening degree θ2, so that the opening degree of the first valve body 27 is rotated from the maximum opening degree to the direction in which the first passage 30 is closed. It has been.

Next, a characteristic configuration of the present invention will be described with reference to FIG.
The first passage 30 is provided as a cylindrical space whose axis α is a straight line. The second passage 31 is provided as a cylindrical space whose axis β is a straight line.
Here, the axis α and the axis β are orthogonal to each other.

Then, if the second valve body 25 in a state in which the second passage 31 is fully closed is moved in the direction of the axis β toward the first passage 30, a passage region γ through which the second valve body passes is set. When considered, a part of the rotation region δ of the first valve element 27 exists in the passage region γ.
Here, the rotation region δ is a region through which the first valve body 27 passes when the first valve body 27 rotates.
The first valve body 27 is arranged so as to approach the second passage 31 for the purpose of reducing the size of the valve unit 1, and is formed by removing a part of the passage forming member 32 on the upstream side of the first passage 30. ing.

And the overhang | projection part 50 which shields a part of rotation area | region (delta) with respect to the flow of the EGR gas is provided in the wall of the 1st channel | path 30 flow upstream of the 2nd channel | path 31.
More specifically, if the portion in the passage region γ of the overhang portion 50 is moved in the direction of the axis β toward the EGR gas flow side in the second passage 31, There is an overlap with the rotation region δ.
In addition, the overhang | projection part 50 may be formed integrally with the 2nd channel | path 31, and may be fixed to the 2nd channel | path 31 after forming in a different body.

[Effects of Reference Example]
In the valve unit 1 of the reference example, the second passage 31 is provided as a cylindrical space in which the axis β is a straight line, and the second valve body 25 in a state in which the second passage 31 is fully closed is assumed to be the first passage. Considering the passage region γ through which the second valve body 25 passes when moving in the direction of the axis β toward 30, a part of the rotation region δ of the first valve body 27 exists in the passage region γ.
The wall of the second passage 31 is provided with an overhang portion 50 that shields a part of the rotation region δ of the first valve body 25 from the flow of EGR gas.

  As a result, the overhanging portion 50 suppresses the flow of the EGR gas that has flowed into the first passage 30 from the second passage 31 toward the first valve body 27, and moves toward the downstream side of the flow in the first passage 30. It functions as the downstream side guidance means 51 which promotes.

For this reason, in the valve unit 1, the occurrence of water droplets on the first valve body 27 can be suppressed by suppressing the arrival of EGR gas to the first valve body 27.
As a result, even when the temperature of the intake air is low, the compressor 22 of the turbocharger 4 can be prevented from being eroded by water droplets.

[Example 1]
The valve unit 1 of Example 1 is shown in FIG. In addition, the same function thing as the reference example is attached | subjected and shown.
FIG. 4A shows a plan view of the first valve element 27.
The first valve body 27 is a plate-like butterfly valve, and is provided with a hole 52 that penetrates obliquely with respect to the thickness direction of the first valve body 27.

Here, as shown in FIG. 4A, the first valve body 27 rotates around the axis ζ that is the rotation center of the shaft 33. Further, a plurality of holes 52 are provided in the upper and lower portions of the shaft 33 in the direction of the axis ζ in parallel with the axis ζ. Each hole 52 has an elliptical shape having a major axis in the axis ζ direction.
Thereby, the arrival of EGR gas to the first valve element 27 can be suppressed by the flow of the intake air passing through the hole 52. The hole 52 functions as the downstream guide means 51 that promotes the flow of the EGR gas flowing into the first passage 30 from the second passage 31 toward the downstream side of the flow in the first passage 30.
In addition, an air curtain-like air flow can be formed by arranging a plurality of holes 52 having an elliptical shape having the major axis in the axis ζ direction in parallel with the axis ζ in the axis ζ direction, so that EGR gas to the first valve body 27 can be formed. Can be more effectively suppressed.

For this reason, similarly to the reference example, in the valve unit 1, generation of water droplets on the first valve body 27 can be suppressed by suppressing the arrival of EGR gas to the first valve body 27.
As a result, even when the temperature of the intake air is low, the compressor 22 of the turbocharger 4 can be prevented from being eroded by water droplets.

[Modification]
Various modifications can be considered for the present invention without departing from the gist thereof.
For example, according to the embodiment, the first shaft 33 exists in the passage region γ, but the present invention is not limited to this aspect, and the first shaft 33 may be arranged outside the passage region γ.
Further, according to the reference example, the overhang portion 50 is provided on the wall of the second passage 31, but the overhang portion 50 may be provided on the wall of the first passage 30.

Further, according to the embodiment, the first valve body 27 and the second valve body 25 are each driven to rotate by one electric actuator 35 via the link device 36, but the first valve body 27 and The second valve bodies 25 may be driven by individual electric actuators 35, respectively.
Alternatively, the first valve body 27 and the second valve body 25 may be driven by a speed reduction mechanism 39 that drives each of the electric motor 35, the first valve body 27, and the second valve body 25 without using the link device 36. Good.

In addition, according to the embodiment, the axis α of the first passage 30 and the axis β of the second passage 31 are orthogonal to each other, but the first passage 30 and the axis β are intersected at a predetermined angle. The second passage 31 may be connected.
Furthermore, when the first passage 30 and the second passage 31 are connected, the first passage 30 and the second passage 31 may be connected so that the axis α and the axis β do not intersect.

Further, according to the first embodiment, the plurality of holes 52 are provided in parallel with the axis ζ in the direction of the axis ζ, but the holes 52 may be formed as slit-like long holes extending in the direction of the axis ζ as shown in FIG. Good.
In the embodiment, the valve unit 1 is provided with either the overhanging portion 50 or the hole 52 as the downstream side guiding means 51. However, the valve unit 1 is provided with both the overhanging portion 50 and the hole 52. It is good also as a structure provided with.

DESCRIPTION OF SYMBOLS 1 Valve unit 2 Engine intake / exhaust system (Intake / exhaust system) 3 Engine 4 Turbocharger 21 Turbine 22 Compressor 25 2nd valve body 27 1st valve body 30 1st channel | path 32 Path | route formation member 51 Downstream side guidance means β Axis line γ passage area δ rotation region

Claims (3)

A unit assembled to an intake / exhaust system (2) for supercharging intake air sucked into the engine (3) to the engine (3) by a turbocharger (4);
Used to recirculate low-pressure EGR gas, which is low-pressure exhaust gas that has passed through the turbine (21) of the turbocharger (4), into the flow of intake air and to guide it to the compressor (22) of the turbocharger (4). In the valve unit (1),
A first passage (30) through which intake air flows and a second passage (31) connected to the first passage (30) are provided, and low pressure EGR gas is introduced into the second passage (31) to introduce the first passage (31). A passage forming member (32) for joining the intake air flowing through one passage (30);
A first valve body (27) housed in the first passage (30) and driven to rotate to restrict the flow of intake air;
A second valve body (25) housed in the second passage (31) and driven to rotate to restrict the flow of the low-pressure EGR gas;
The second passage (31) is provided as a cylindrical space whose axis (β) is a straight line,
The second valve body (25) in a state in which the second passage (31) is fully closed is temporarily directed toward the first passage (30) in the axis (β) direction of the second passage (31). Considering the passage region (γ) through which the second valve body (25) passes when moved to
A part or all of the rotation region (δ) of the first valve body (27) exists in the passage region (γ),
The first valve body (27) has a plate shape in which the thickness direction is not the intake air flow direction in the rotation region (δ),
In the first valve body (27), the flow of the low-pressure EGR gas flowing into the first passage (30) from the second passage (31) is directed to the downstream side of the flow in the first passage (30). Downstream guiding means (51) for promoting
The downstream guiding means (51) is a hole (52) penetrating the first valve body (27) whose axial direction is the flow direction of the intake air at a predetermined position of the rotation region (δ). The valve unit (1). The valve unit (1) according to claim 1,
The first valve body (27) rotates about the axis (ζ) as a rotation center,
The valve unit (1), wherein a plurality of the holes (52) are provided in the direction of the axis (ζ). The valve unit (1) according to claim 1,
The first valve body (27) rotates about the axis (ζ) as a rotation center,
The valve unit (1), wherein the hole (52) is a long hole extending in the direction of the axis (ζ).

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