JP6011501B2 - Valve device - Google Patents

Description

  The present invention relates to a valve device including a low pressure EGR valve that opens and closes a low pressure EGR passage connected to an intake passage, and an intake throttle valve that opens and closes the intake passage.

2. Description of the Related Art Conventionally, a low pressure EGR device that recirculates a part of a relatively low pressure and low temperature exhaust gas as low pressure EGR gas to an intake passage is known (for example, see Patent Documents 1 and 2).
The low pressure EGR device is a butterfly type low pressure EGR valve that adjusts the flow rate of the low pressure EGR gas flowing through the low pressure EGR passage, and the opening degree of the intake passage upstream of the low pressure EGR passage in conjunction with the opening and closing operation of the low pressure EGR valve. A valve device having a butterfly type intake throttle valve to be adjusted; When the low-pressure EGR valve maximizes the opening of the low-pressure EGR passage, the intake throttle valve restricts the intake passage most (this state is called intake fully closed), and the flow rate of EGR gas recirculated to the intake passage is reduced. increase.

Patent Documents 1 and 2 disclose a technique in which an intake passage and a low-pressure EGR passage are connected at a right angle in response to a request for downsizing a valve device or the like.
In the valve device of Patent Document 1, the intake throttle valve is arranged so that the intersection of the flow path shaft of the low pressure EGR passage and the flow passage shaft of the intake passage is the center of rotation.

However, in this structure, the flow path for flowing EGR gas to the intake passage when the intake is fully closed is throttled in the vicinity of the intake throttle valve. This phenomenon is referred to as “EGR aperture phenomenon”. When this “EGR throttling phenomenon” occurs, there arises a problem that the flow rate of EGR gas decreases.
On the other hand, in the valve device of Patent Document 1, when the intake is fully closed, the intake throttle valve is present in an inclined state with respect to the flow axis of the intake passage, thereby flowing from the low pressure EGR passage to the downstream side of the intake passage. Thus, the flow of EGR gas can be guided. This function is called an “EGR flow guide function”.

On the other hand, in the valve device of Patent Document 2, the intake throttle valve is arranged in the intake passage sufficiently upstream from the position where the connection port of the low pressure EGR passage opens.
However, in the case of this structure, although the “EGR throttling phenomenon” does not occur, the “EGR flow guide function” is not exhibited. For this reason, the EGR gas flowing out from the connection port advances straight along the flow path axis of the low pressure EGR passage and collides with the flow passage wall of the intake passage to cause pressure loss, resulting in a decrease in the flow rate of the EGR gas. The problem of end up occurs.

  In order to increase the flow rate of EGR gas, there is a method of increasing the passage diameter of the low pressure EGR passage. However, increasing the passage diameter inhibits the miniaturization of the valve device.

JP 2012-237306 A JP 2012-127204 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to increase the flow rate of EGR gas while reducing the size of the valve device in the valve device of the low pressure EGR device. And

A valve device according to the present invention includes a supercharger having an exhaust turbine disposed in an exhaust passage and a compressor disposed in an intake passage, and a high-pressure EGR device and a low-pressure EGR device that recirculate part of the exhaust to the intake passage. In the intake / exhaust system for an internal combustion engine, a valve device that constitutes a low-pressure EGR device, and a low-pressure EGR passage that is orthogonal to the flow passage axis x of the intake passage when its own flow passage shaft y is extended into the intake passage; A butterfly-type low-pressure EGR valve that opens and closes the low-pressure EGR passage, a butterfly-type intake throttle valve that is disposed in the intake passage, restricts the intake passage, and increases the flow rate of EGR gas introduced into the intake passage, and low-pressure EGR interlocked driven shaft with each other serving as the rotation center of the valve and the intake throttle valve, when the low-pressure EGR valve to maximize the degree of opening of the low-pressure EGR passage, the intake throttle valve is most an intake passage And the intake throttle valve posture when the intake is fully closed, and the upstream end of the intake throttle valve is located closer to the connection port of the low pressure EGR passage than the center of rotation. The attitude of the intake throttle that is inclined with respect to the flow path axis x of the intake passage so that the downstream end of the intake throttle valve is positioned so that the downstream end of the intake throttle valve is positioned farther from the connection port than the rotation center With.

The downstream end of the intake throttle valve is located downstream of the intersection point o between the flow path axis x of the intake passage and the flow path axis y of the low pressure EGR passage when intake is fully closed.
Further, in the flow path through which the EGR gas flows through the low pressure EGR passage to the intake passage downstream of the intake throttle valve when the intake is fully closed, a portion having the smallest flow path area is provided in the low pressure EGR passage.

  According to this, since the “EGR throttling phenomenon” does not occur and the “EGR flow guide function” can be maintained, the flow rate of the EGR gas is increased without increasing the diameter of the low pressure EGR passage. be able to. That is, the flow rate of the EGR gas can be increased while downsizing the valve device.

It is the schematic of the intake / exhaust system of an internal combustion engine. It is sectional drawing explaining the basic composition of a valve apparatus. It is a schematic diagram of the valve apparatus of an Example. It is a schematic diagram of the valve apparatus of a prior art example. It is a schematic diagram of the valve apparatus of a prior art example. It is the correlation figure which showed the relationship between the distance C and flow volume.

  The mode for carrying out the present invention will be described in detail with reference to the following examples.

〔Example〕
Examples will be described with reference to FIGS.
First, an intake / exhaust system of an internal combustion engine to which the valve device of this embodiment is applied will be described with reference to FIG.
The intake / exhaust system includes an intake passage 2 that guides intake air to the engine 1, an exhaust passage 3 that discharges exhaust from the engine 1, an exhaust turbine 4 that is disposed in the exhaust passage 3, and a compressor 5 that is disposed in the intake passage 2. And a high pressure EGR device and a low pressure EGR device that recirculate a part of the exhaust gas to the intake passage 2.

  In the intake passage 2, an air cleaner 8 that removes foreign matter from intake air from the upstream side of intake air, a compressor 5 of a supercharger, an intercooler 9 that cools intake air compressed by the compressor 5, a throttle valve 10 that adjusts the intake air amount, A surge tank 11 and the like that form a volume chamber are arranged.

  In the exhaust passage 3, an exhaust turbine 4 of a supercharger, a DPF 12 that collects particulate matter (PM) contained in the exhaust, and the like are arranged from the exhaust upstream side.

  The exhaust turbine 4 converts exhaust energy into rotational force, and the compressor 5 is coaxially connected to the exhaust turbine 4 and rotates by the rotational force of the exhaust turbine 4 to compress intake air.

The high-pressure EGR device is a device that recirculates a portion of the relatively high-pressure and high-temperature exhaust immediately after being discharged from the engine 1 to the intake passage 2 as high-pressure EGR gas.
The high-pressure EGR device includes a high-pressure EGR passage 13 that connects the exhaust passage 3 upstream of the exhaust turbine 4, the intake passage 2 downstream of the throttle valve 10, and high-pressure EGR gas that flows through the high-pressure EGR passage 13. A high-pressure EGR valve that adjusts the flow rate; a high-pressure EGR cooler that cools the high-pressure EGR gas; and a switching valve that switches between a path that passes through the high-pressure EGR cooler and a path that bypasses the high-pressure EGR cooler. .

The low pressure EGR device is a device that recirculates a part of the relatively low pressure and low temperature exhaust gas to the intake passage 2 as low pressure EGR gas.
The low-pressure EGR device includes a low-pressure EGR passage 20 that connects an exhaust passage 3 downstream of the exhaust turbine 4 (in the present embodiment, downstream of the DPF 12) and an intake passage 2 upstream of the compressor 5; A low-pressure EGR valve 21 that adjusts the flow rate of the low-pressure EGR gas that flows through the EGR passage 20, a low-pressure EGR cooler 22 that cools the low-pressure EGR gas, and an intake upstream of the low-pressure EGR passage 20 in conjunction with the opening and closing operation of the low-pressure EGR valve 21 And an intake throttle valve 23 for adjusting the opening of the intake passage 2.

The low pressure EGR valve 21 and the intake throttle valve 23 are unitized as one valve device 24 driven by one actuator.
Next, the basic configuration of the valve device 24 will be described with reference to FIG.

  The valve device 24 includes an EGR pipe 20a that forms part of the low-pressure EGR passage 20, a low-pressure EGR valve 21 that is arranged in the EGR pipe 20a, an intake pipe 2a that forms part of the intake passage 2, and an intake pipe 2a. And an interlocking drive mechanism for interlockingly driving the low-pressure EGR valve 21 and the intake throttle valve 23.

  The EGR pipe 20a and the intake pipe 2a are connected at a right angle. That is, as shown in FIG. 3, the flow path axis y of the EGR pipe 20a is orthogonal to the flow path axis x of the intake pipe 2a when extended into the intake passage.

  The low pressure EGR valve 21 is a butterfly valve, and a shaft 26 serving as a rotation center is rotatably supported by the EGR pipe 20a.

  The intake throttle valve 23 is a butterfly valve that throttles the intake passage 2 and increases the flow rate of EGR gas introduced into the intake passage 2, and a shaft 27 serving as a rotation center is rotatably supported by the intake pipe 2a. The structure of the intake throttle valve 23 will be described in detail later.

The interlocking drive mechanism includes an actuator 29 that generates a rotational driving force, and a link mechanism 30 that connects the shaft 26 and the shaft 27.
The actuator 29 is an electric motor, for example, and applies a rotational driving force to the shaft 26 via a power transmission mechanism.

  The power transmission mechanism includes a pinion 31 provided on the output shaft of the electric motor 30, a reduction gear 32 that meshes with the pinion 31, a small-diameter gear 33 that is provided integrally with the reduction gear 32 and rotates around a common central axis, The valve gear 34 meshes with the small diameter gear 33. The valve gear 34 is fixed to the shaft 26, and the rotation of the electric motor is transmitted to the shaft 26.

The shaft 26 of the low pressure EGR valve 21 is provided in parallel with the shaft 27 of the intake throttle valve 23.
The shaft 26 and the shaft 27 are connected via a link mechanism, and the shaft 27 is configured to rotate as the shaft 26 is rotated by the electric motor.

  The link mechanism 30 includes a drive plate 38 that rotates integrally with the shaft 26, and a driven plate 39 that rotates integrally with the shaft 27, and is formed on the cam plate 38 a formed in the drive plate 38 and the driven plate 39. It is comprised by engagement with the pin 39a made.

  The low-pressure EGR valve 21 and the intake throttle valve 23 are driven by a single actuator by the interlock driving mechanism described above. When the low pressure EGR valve 21 maximizes the opening of the EGR pipe 20a, the intake throttle valve 23 fully closes the intake pipe 2a.

  When the low-pressure EGR valve 21 opens the low-pressure EGR passage 20, the EGR gas merges with the air flowing from the intake upstream side of the position of the connection port 40 of the EGR pipe 20a, and flows to the intake downstream.

The intake throttle valve 23 has an elliptical plate shape and rotates integrally with the shaft 27.
When the intake is fully closed, the intake throttle valve 23 is inclined with respect to the flow path axis x. That is, the plate thickness direction is not parallel to the flow path axis x.
As shown in FIG. 3, when the intake is fully closed, the intake throttle valve 23 is inclined so as to lie toward the downstream side of the intake pipe 2a. That is, in the direction along the flow path axis y, the upstream end 23a of the intake throttle valve 23 is located closer to the connection port 40 of the EGR pipe 20a than the rotation center (shaft 27), and the connection port is located more than the rotation center. It is inclined so that the downstream end 23b of the intake throttle valve 23 is located on the side far from 40.

[Features and effects of this embodiment]
The features of this embodiment will be described with reference to FIG.
The intake throttle valve 23 of this embodiment is arranged so that the downstream end 23b is located on the intake downstream side of the intersection point o between the flow path axis x and the flow path axis y when the intake is fully closed.

  Here, it is a flow path formed by the EGR pipe 20a and the intake pipe 2a downstream of the intake throttle valve when the intake is fully closed, and the EGR gas can flow through the EGR pipe 20a to the intake pipe 2a downstream of the intake throttle valve 23. Such a flow path is called an EGR merge flow path 50.

  In the present embodiment, in the EGR merging flow channel 50, a portion having the smallest flow channel area is provided in the EGR pipe 20a. That is, the shaft 27 is positioned upstream of the intersection point o, and the flow path area B of the EGR pipe 20a is smaller than the minimum flow path area A at the intersection of the intake pipe 2a and the EGR pipe 20a. ing.

In order to explain the function and effect of this embodiment, a conventional valve device will be described.
Conventional Example 1 will be described with reference to FIG. 4, and Conventional Example 2 will be described with reference to FIG.

  In Conventional Example 1, the downstream end 23b is located on the intake downstream side of the intersection o. For this reason, the “EGR flow guide function” is exhibited. In other words, the EGR gas flowing out from the connection port 40 is guided by the inclined intake throttle valve 23, and the EGR gas flows smoothly downstream of the intake throttle valve 23.

  However, in Conventional Example 1, the minimum flow path area A at the intersection is smaller than the flow path area of the EGR pipe 20a. For this reason, the “EGR aperture phenomenon” occurs. That is, the EGR merge flow path 50 is throttled at the position of the minimum flow path area A due to the presence of the intake throttle valve 23, and the flow rate of EGR gas is reduced.

  On the other hand, in the prior art example 2, the rotation center of the intake throttle valve 23 is located upstream of the intersection point o, and the minimum flow path area at the intersection is larger than the flow path area of the EGR pipe 20a. The phenomenon does not occur.

  However, in the conventional example 2, since the downstream end 23b is located on the intake upstream side with respect to the intersection point o, the “EGR flow guide function” is not achieved. That is, the EGR gas from the EGR pipe 20 a goes straight along the flow path axis y and easily collides with the wall surface of the intake pipe 2 a facing the connection port 40. For this reason, a pressure loss becomes large and the flow volume of EGR gas will reduce as a result.

  As described above, in the conventional example, the flow rate of EGR gas is reduced due to the occurrence of the “EGR throttling phenomenon” or the disappearance of the “EGR flow guide function”.

In contrast, in this embodiment, the “EGR throttling phenomenon” does not occur and the “EGR flow guide function” can be maintained.
That is, in the present embodiment, the downstream end 23b of the intake throttle valve 23 is located on the intake downstream side of the intersection point o when the intake is fully closed. For this reason, the EGR gas flowing out from the connection port 40 can be guided to the downstream side of the intake throttle valve 23 by the intake throttle valve 23.

In the present embodiment, in the EGR merging flow channel 50, a portion having the smallest flow channel area is provided in the EGR pipe 20a. That is, the shaft 27 is positioned upstream of the intersection point o, and the minimum flow area A at the intersection of the intake pipe 2a with the EGR pipe 20a is larger than the flow area B of the EGR pipe 20a. Yes.
For this reason, unlike the conventional example 1, the EGR merging flow path 50 is not throttled by the presence of the intake throttle valve 23.

Here, C is the distance from the intersection point o in the direction parallel to the flow path axis x to the downstream end 23b. Assume that the intersection point o is a zero point, and that the downstream end 23b is on the downstream side of the intersection point o, it is positive.
FIG. 6 shows the relationship between the distance C and the flow rate.

In the region where the distance C is negative, the “EGR flow guide function” is lost as in the second conventional example. For this reason, pressure loss is large and only a small flow rate can be obtained.
When the distance C is increased, the “EGR flow guide function” is exhibited, so that the pressure loss is reduced and the flow rate is increased. However, if the distance C is too large, the EGR merging flow path 50 is throttled by the intake throttle valve 23 as in Conventional Example 1, and the “EGR throttle phenomenon” occurs.
The arrangement of the intake throttle valve 23 of the present embodiment is an arrangement in which the “EGR throttle phenomenon” does not occur and the “EGR flow guide function” can be maintained, and the flow rate of the EGR gas can be increased.

As described above, according to the present embodiment, the “EGR throttling phenomenon” does not occur and the “EGR flow guide function” can be maintained, so that the EGR pipe 20a does not have to be increased in diameter without increasing the EGR diameter. The gas flow rate can be increased. That is, the flow rate of the EGR gas can be increased while downsizing the valve device.

  2 intake passage, 2a intake piping, 20 low pressure EGR passage, 20a EGR piping, 21 low pressure EGR valve, 23 intake throttle valve, 23a upstream end of intake throttle valve, 23b downstream end of intake throttle valve, 24 valve device, 27 shaft, 29 Actuator, 30 Link mechanism, 40 Connection port

Claims (2)

An intake passage (2) for guiding intake air to the internal combustion engine (1), an exhaust passage (3) for exhausting exhaust gas from the internal combustion engine (1), and an exhaust turbine (4) disposed in the exhaust passage (3) ) And a compressor (5) disposed in the intake passage (2), and a high-pressure EGR device and a low-pressure EGR device that recirculate a part of the exhaust to the intake passage (2), A low-pressure EGR device connects the exhaust passage (3) on the exhaust downstream side of the exhaust turbine (4) and the intake passage (2, 2a) on the intake upstream side of the compressor (5) to supply EGR gas to the intake air. In the intake and exhaust system of the internal combustion engine (1) configured to recirculate to the passage (2, 2a),
A valve device constituting the low-pressure EGR device ,
A low pressure EGR passage (20, 20a) orthogonal to the flow passage axis x of the intake passage (2, 2a) when its own flow passage axis y is extended into the intake passage (2, 2a);
A butterfly-type low-pressure EGR valve (21) for opening and closing the low-pressure EGR passage (20, 20a);
A butterfly type intake throttle valve (2) disposed in the intake passage (2, 2a) to restrict the intake passage (2, 2a) and increase the flow rate of EGR gas introduced into the intake passage (2, 2a). 23)
The low pressure EGR valve (21) and the shaft (26, 27), which are the rotation centers of the intake throttle valve (23), are driven together, and the low pressure EGR valve (21) is in the low pressure EGR passage (20, 20a). An interlocking drive mechanism (29, 30) that causes the intake throttle valve (23) to fully close the intake passage (2, 2a) when the opening of the intake valve is maximized,
A posture of the intake fully closed the intake throttle valve (23), said rotation center (27) the intake throttle valve on the side closer to the connection port (40) of the low-pressure EGR passage (20, 20a) than The upstream end (23a) of (23) is located, and the downstream end (23b) of the intake throttle valve (23) is located on the side farther from the connection port (40) than the rotation center (27). The posture of the intake throttle valve (23) inclined with respect to the flow path axis x of the intake passage (2, 2a) ,
The downstream end (23b) of the intake throttle valve (23) has a flow path axis x of the intake passage (2, 2a) and a flow path axis y of the low pressure EGR passage (20, 20a) when the intake is fully closed. Is located on the downstream side of the intake passage (2, 2a) from the intersection o of
In the flow path where EGR gas flows through the low pressure EGR passage (20, 20a) to the intake passage (2, 2a) on the downstream side of the intake throttle valve when the intake air is fully closed, the portion with the smallest flow area is the A valve device provided in the low pressure EGR passage (20, 20a). The valve device according to claim 1,
The valve device, wherein the rotation center (27) is located upstream of the intersection point o in the intake passage (2, 2a).

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