JP6040918B2 - EGR valve device - Google Patents

Description

  The present invention is applied to an EGR device of an internal combustion engine (hereinafter also referred to as an engine) mounted on a vehicle such as an automobile, for example, an engine in which a supercharger is mounted in an intake / exhaust system, and is provided in an exhaust passage of the engine. More particularly, the present invention relates to an EGR valve device that collects valves in an EGR device that recirculates a part of exhaust gas that has passed through an exhaust gas purification device as an EGR gas to an intake passage upstream of a compressor of a supercharger.

Conventionally, as a means for suppressing NOx (nitrogen oxide) contained in engine exhaust gas, an EGR technique in which a part of the exhaust gas is recirculated to the intake air as EGR gas is known.
Although this EGR technique can reduce the amount of NOx by increasing the amount of EGR gas, if EGR gas is recirculated excessively, particulate matter (PM) is likely to be generated in recent years. A method of reducing NOx while suppressing the generation of graphite by combining a high-pressure system and a low-pressure EGR apparatus has been used.

In the case of such a system, various ideas are required especially for the low-pressure EGR apparatus. In other words, this EGR device must have a system configuration in which the EGR gas is returned from the operation region where the exhaust pressure is relatively low to the operation region where the intake negative pressure is low, and therefore a small amount of EGR gas cannot be returned to the engine. Although possible, it becomes difficult to return a large amount of EGR gas to the engine.
Therefore, as shown in FIG. 6, by arranging an intake throttle valve 120 for intake (fresh air) control in the intake flow path 110 on the intake upstream side from the junction with the EGR flow path 100, a large amount of EGR gas is generated. In the operation region where it is required to return to the engine, as shown by the arrow in the figure, the opening degree of the intake throttle valve 120 is controlled in the direction in which the intake throttle valve 120 is closed, that is, the intake negative pressure is increased. An EGR device that recirculates EGR gas according to the opening degree has been proposed.

[Problems of the prior art]
However, in such an EGR device, in addition to the drive means such as an EGR valve and an electric actuator for opening and closing the valve, an intake throttle valve and a similar drive means for opening and closing the valve are required. The entire system will inevitably become larger, and restrictions on vehicle mounting will be forced.
For this reason, both the EGR valve and the intake throttle valve are installed in a common valve housing to form one unit as an EGR valve device, and the opening / closing control of both valves is performed by a common driving means (electric actuator). It is considered to be performed and is being put to practical use (for example, see Patent Document 1).
According to the EGR valve device described in Patent Document 1, by arranging the intake throttle valve at the merging portion of the valve housing, the EGR device as a whole can be made compact, and restrictions on vehicle mounting are eased. Promising for future EGR devices.

JP 2012-177314 A

  By the way, the environment surrounding the vehicle is becoming more severe year by year, and accordingly, this type of EGR apparatus is expected to be further reduced in size and performance. Therefore, regarding the EGR valve device that plays a central role in the EGR device, both functionally and physically, how to match the EGR performance so as to exhibit suitable EGR performance following the high performance of the engine. This is an immediate problem for the contractor.

The present inventors have made many experiments and researches with the aim of further improving the matching technology.However, after examining the actual usage, it has been found that the following problems are inherent. I found it.
(1) In this type of EGR device, as described above, by closing the intake throttle valve, a large negative intake pressure is generated at the junction, and a large amount of EGR gas is returned to the engine.
(2) However, as the output of the engine increases, it is necessary to return the EGR valve to the engine as much as possible by fully opening the EGR valve (or an intermediate opening close to it) with the intake throttle valve fully opened. A new operating area has arisen.
(3) In this operating range, it was confirmed that the desired amount of EGR gas does not recirculate unexpectedly even when the intake throttle valve is fully opened and the EGR valve is fully opened (or the desired opening is also an intermediate opening). . As a result of investigating the cause, it was thought that a sufficient EGR function was exhibited by disposing the intake throttle valve at the junction. However, when the intake throttle valve is fully opened, the valve body becomes EGR. It has been found that the EGR function is impaired because the gas flow is partially inhibited.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an EGR valve device capable of exhibiting EGR performance suitable for engine performance while having a compact configuration. It is in.

[Means of Claim 1]
The EGR valve device according to claim 1 is an intake passage that supplies intake air to the engine, an EGR passage that guides engine exhaust gas to the intake passage as EGR gas, and an intake upstream side and intake air in the intake passage A valve housing having a merging portion for joining the EGR flow path in a T-shape with the downstream side, an EGR valve provided in the valve housing for adjusting the opening degree of the EGR flow path, and a merging portion The basic configuration includes an intake throttle valve that adjusts the opening degree of the intake flow path and generates intake negative pressure at the merging portion,
The valve housing has a minimum effective flow area formed between the fully open position of the intake throttle valve and the merging side opening of the EGR flow path on the downstream side of the intake side of the intake throttle valve at the merging portion. It is characterized by having an enlarged flow path portion that makes the intake channel more than 1/2 of the maximum effective flow area when the valve is fully opened.

According to the EGR valve device having the above configuration, when the intake throttle valve is in the fully open position, a sufficient flow area can be ensured between the fully open position of the intake throttle valve and the merging side opening of the EGR flow path. When the EGR valve is fully opened, a sufficient amount of EGR gas can be recirculated without being obstructed by the intake throttle valve.
In addition, it is a simple configuration in which only the enlarged flow path portion is provided, and the valve housing itself can be easily manufactured as usual (without special cutting work).
Therefore, it is possible to provide an EGR valve device capable of exhibiting EGR performance adapted to the required performance of the engine while having a compact one-unit configuration.

[Means of claim 2]
The EGR valve device according to claim 2 is applied regardless of the flow area of the intake flow path, and the valve housing is arranged at the intake downstream side of the intake throttle valve at the merging portion. An expanded flow path portion that expands the minimum effective flow area formed between the fully opened position of the EGR flow path and the merge side opening of the EGR flow path to be larger than the valve opening area of the EGR flow path when the EGR valve is fully opened It is characterized by having.

  In such an EGR valve device, a desired EGR gas flow area at the fully open position of the intake throttle valve can be secured regardless of the flow area of the intake flow path, and the valve housing itself can be easily manufactured as usual. The effect similar to that of the means of claim 1 can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram when an EGR valve is in a fully open position and an intake throttle valve is in a fully closed position for explaining the first embodiment of an EGR valve device to which the present invention is applied (Example 1). BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view when the EGR valve is in an intermediate opening position and the intake throttle valve is in a fully open position, mainly for explaining the structure of a valve housing in the EGR valve device (Example 1). It is sectional drawing which shows the example of preparation of the said valve housing. FIG. 2 shows a second embodiment of an EGR valve device to which the present invention is applied, which is mainly used for explaining the structure of the valve housing, and is a schematic view when the EGR valve is in an intermediate opening position and the intake throttle valve is in a fully open position. (Example 2) which is sectional drawing. It is a mimetic diagram showing roughly the whole composition of an engine intake-exhaust system. It is typical sectional drawing which shows the relationship between the low pressure EGR valve and the intake throttle valve in the conventional EGR apparatus (prior art).

  Hereinafter, the best mode for carrying out the present invention will be described in detail according to two embodiments shown in the drawings.

Each embodiment shows an EGR valve device suitable for an internal combustion engine (engine) in which a supercharger is mounted in an intake / exhaust system, as a representative example of an EGR valve device to which the present invention is applied. After reviewing the basic configuration of the intake / exhaust system of the engine, the features of each embodiment of the present invention and the basic functions of the present invention will be described in order, and finally the effects of the features of the present invention will be summarized. Enumerate.
In each embodiment, the same or equivalent parts are denoted by the same reference numerals, and redundant description is omitted.

[Example 1]
[Basic structure of intake and exhaust system]
The overall configuration of an intake / exhaust system for an engine to which the present invention is applied will be described with reference to FIG.
The engine 1 is, for example, a diesel engine that uses light oil as a fuel or a gasoline engine that uses gasoline, and an intake passage 2 that introduces intake air (intake air, fresh air) into the cylinder of the engine 1, and a cylinder And an exhaust passage 3 for exhausting the exhaust gas generated by the combustion of the fuel to the atmosphere.
The supercharger K includes, for example, an exhaust turbine 4 that converts energy of exhaust gas discharged from the engine 1 into rotational force, and a compressor 5 that is coaxially connected to the exhaust turbine 4. A turbocharger that compresses intake air by rotation and supplies the compressed air to the engine 1 from the intake passage 2.

In the intake passage 2, an air cleaner 6 that removes foreign matters such as dust contained in the outside air taken in from the intake port 6 a, the compressor 5, the intercooler 7 that cools the intake air compressed by the compressor 5, and the intake air amount are adjusted. A throttle body 9 incorporating a throttle valve 8 and a surge tank 10 forming a predetermined volume chamber are disposed.
The exhaust passage 3 is provided with the exhaust turbine 4 and the DPF 11 (abbreviation of diesel particulate filter) that collects particulate matter (PM) contained in the exhaust gas.
The DPF 11 is an example of an exhaust purification device.

[Basic configuration of EGR equipment]
Next, the EGR device will be described.
The intake and exhaust system of the engine 1 is provided with a high pressure EGR device and a low pressure EGR device.

The high-pressure EGR device is a high-pressure exhaust gas recirculation device that recirculates a part of relatively high-temperature and high-pressure exhaust gas immediately after being discharged from the engine 1 to the intake side as high-pressure EGR gas.
As shown in the upper part of FIG. 5, this high pressure EGR device has an exhaust passage 3 upstream of the exhaust turbine 4 and an intake passage 2 downstream of the throttle valve 8 (in this embodiment, a surge tank 10 ), A high pressure EGR valve 13 that adjusts the flow rate of the high pressure EGR gas that recirculates to the intake side through the high pressure EGR flow passage 12, and the high pressure EGR gas that recirculates to the intake side. A high pressure EGR cooler 14 that bypasses the high pressure EGR cooler 14, a bypass EGR flow path 15 that bypasses the high pressure EGR cooler 14, an EGR path through which the high pressure EGR gas recirculates to the intake side via the high pressure EGR cooler 14, and a bypass EGR flow path 15. And an EGR flow path switching valve 16 for switching an EGR path that recirculates to the intake side.

The low-pressure EGR device is a low-pressure exhaust gas recirculation device that recirculates a part of relatively low-temperature and low-pressure exhaust gas to the intake side as low-pressure EGR gas.
As shown in the lower part of FIG. 5, this low-pressure EGR device has an intake air flow upstream of the exhaust flow path 3 and the compressor 5 on the exhaust downstream side of the exhaust turbine 4 (in this embodiment, the downstream side of the exhaust of the DPF 11). A low pressure EGR flow path 17 that connects the passage 2, a low pressure EGR valve 18 that adjusts the flow rate of the low pressure EGR gas that recirculates to the intake side through the low pressure EGR flow path 17, and a low pressure EGR gas that recirculates to the intake side A low pressure EGR cooler 19 that cools and an intake throttle valve 20 that adjusts the opening degree of the intake flow path 2 in conjunction with the operation of the low pressure EGR valve 18 opening and closing the low pressure EGR flow path 17 are provided.

Next, a basic cooperative relationship between the low pressure EGR valve 18 and the intake throttle valve 20 according to the present invention will be described mainly with reference to FIG.
In the following description, since each functional element relates to a low pressure system, except for special cases, the low pressure system functional elements such as “low pressure EGR flow path 17 and low pressure EGR valve 18” are simply referred to as “EGR”. These are abbreviated as “channel 17 and EGR valve 18”.

  The EGR valve 18 and the intake throttle valve 20 are integrated into one valve housing VH together with an interlocking mechanism to be described later, and are integrally configured as an EGR valve unit U. The EGR valve unit U constitutes the EGR valve device of the present invention, and a part of the intake passage 2 and a part of the EGR passage 17 are arranged in a T shape in the valve housing VH. Has been.

The EGR valve 18 is a butterfly valve in which a disc-like valve body 18a rotates integrally with a shaft 18b, and is near the outlet (the confluence-side opening 17a in FIG. 2) of the EGR passage 17 connected to the intake passage 2. Placed in. 1, the left side in the drawing is the air cleaner 6 side, and the right side in the drawing is the engine 1 side.
The EGR valve 18 is centered on a shaft 18b between a fully closed position where the opening degree of the valve body 18a is minimum and a fully open position (a broken line position shown in FIG. 1) where the opening degree of the valve body 18a is maximum. It is provided so as to be able to rotate, and a rotational force generated in an electric actuator (not shown) is transmitted to the shaft 18b via a power transmission device (described below), thereby being rotationally displaced.

The electric actuator is, for example, valve driving means using a DC motor, and the detection angle of a valve angle sensor (not shown) that detects the rotation position of the EGR valve 18 as the valve angle depends on the operating state of the engine 1. Feedback control is performed by an ECU (not shown), which is an electronic control device, so as to coincide with the control target value set in the above.
The power transmission device includes a gear train that decelerates the rotational speed of the DC motor and amplifies the drive torque. The gear train includes a pinion 21 that is attached to the output shaft of the DC motor, a reduction gear 22 that meshes with the pinion 21, and a small diameter that is supported by a central shaft 22 a that is common to the reduction gear 22 and rotates integrally with the reduction gear 22. The gear 23 and a valve gear 24 that meshes with the small-diameter gear 23 are configured. The valve gear 24 is fixed to the shaft 18 b of the EGR valve 18.

As with the EGR valve 18, the intake throttle valve 20 is a butterfly valve in which a disc-shaped valve body 20 a rotates integrally with the shaft 20 b, and the EGR gas inflow of the intake flow path 2 through which EGR gas flows from the EGR flow path 17. It is arranged in the part (connection part with EGR channel 17 = confluence part C in FIG. 2).
The intake throttle valve 20 is connected to the EGR valve 18 through an interlocking mechanism described below, and, as a standard operation, the intake passage 2 is opened in conjunction with the opening operation of the EGR valve 18 opening the EGR passage 17. By reducing the degree, the flow rate of the EGR gas returning to the intake passage 2 is increased.
The interlocking mechanism includes a drive plate 26 that is fixed to the valve gear 24 by the screw 25 and rotates integrally with the EGR valve 18, and a driven plate 27 that is fixed to the shaft 20 b of the intake throttle valve 20 and rotates integrally with the intake throttle valve 20. And cam means (described below) for transmitting the rotation of the drive plate 26 to the driven plate 27.

The cam means includes a cam groove 28 formed in the drive plate 26 and a roller 29 attached to the driven plate 27, and this roller 29 is accommodated in the cam groove 28.
The cam groove 28 has a first cam surface 28a and a second cam surface 28b having different cam profiles. This cam profile is set as follows in the case of standard operation, for example. That is, the first cam surface 28a is configured to reduce the intake throttle while the EGR valve 18 rotates from the fully closed position to an intermediate opening (for example, a desired position between the fully closed position and the fully open position, for example, the solid line position in FIG. 2). A cam profile is formed by an arc of the same length from the rotation center of the drive plate 26 so that the valve 20 is held in the fully open position (position shown in FIG. 2 ). The second cam surface 28b is provided continuously from the first cam surface 28a, and drives the intake throttle valve 20 to the fully closed position when the EGR valve 18 rotates from the intermediate opening to the fully opened position shown in FIG. A cam profile is formed.

The roller 29 is rotatably supported by an arm portion 27 a provided on the driven plate 27.
The driven plate 27 is provided with a substantially circular outer peripheral shape, and is fixed to a shaft 20a that passes through a central portion in the radial direction. The arm portion 27 a that supports the roller 29 is provided in a part of the driven plate 27 in the circumferential direction, and protrudes outward in the radial direction of the driven plate 27. In addition, the tip shape of the arm portion 27a is formed in an arc shape having a certain curvature.
When the drive plate 26 rotates integrally with the EGR valve 18, the above cam means is driven by the roller 29 moving in the cam groove 28 while following the cam profile of the cam groove 28 formed in the drive plate 26. The rotation of the plate 26 is transmitted to the driven plate 27, and the intake throttle valve 20 rotates together with the driven plate 27.

The spring 30 performs intake in the direction opposite to the valve closing direction when the intake throttle valve 20 rotates in the direction to close the intake flow path 2 in conjunction with the opening operation of the EGR valve 18 , that is, in the clockwise direction in FIG. The throttle valve 20 is energized.

[Features of this embodiment]
The EGR valve device (EGR valve unit U) of the present invention is particularly characterized by the flow path configuration in the valve housing VH and the arrangement relationship of the intake throttle valve 20, and will be described in detail with reference to FIG.

The valve housing VH has a T shape as a whole having three connection ports VH1 to VH3. An intake passage 2 for supplying intake air to the engine 1 is provided at the two opposing connection ports VH1 and 2, and an EGR passage 17 for guiding exhaust gas of the engine 1 to the intake passage 2 as EGR gas. Is provided in the remaining connection port VH3. Further, in the central portion of the valve housing VH, the EGR flow path 17 is joined in a T shape between the intake upstream side 2a (air cleaner 6 side) and the intake downstream side 2b (engine 1 side) of the intake flow path 2. It has a junction C.
In the intake flow path 2, the intake upstream side 2 a and the intake downstream side 2 b basically have a circular cross-sectional area of the same diameter except for the merging portion C.
The valve housing VH is equipped with an EGR valve 18 that adjusts the opening degree of the EGR flow path 17 and an intake throttle valve 20 that adjusts the opening degree of the intake flow path 2.

  The intake throttle valve 20 is disposed in the merging portion C, adjusts the opening degree of the intake passage 2, and restricts (closes) the flow area of the intake passage 2, thereby sucking air into the merging portion C. Generate negative pressure. 1 is rotated and displaced from the fully closed position indicated by the broken line in FIG. 1 to the fully open position indicated by the solid line in FIG. 2, but due to the arrangement position, the valve body 20a and the merging side opening 17a of the EGR flow path 17 are located at the fully open position. It will be completely opposite.

  In view of this, the valve housing VH is connected to the intake downstream side 2b of the intake throttle valve 20 in the merging portion C with the merging side opening 17a of the EGR flow path 17 and the intake downstream side 2b of the intake flow path 2. An enlarged flow path portion CX is provided. This enlarged flow path portion CX is a feature of the present invention.

  In the present embodiment, as the expanded flow path portion CX, an inclined shape that allows the merge side opening 17a of the EGR flow path 17 to communicate with the intake downstream side 2b of the intake flow path 2 while expanding toward the intake downstream side 2b. The combined flow path C1 is provided. In other words, at the merging portion C, a corner C0 (shown by a broken line) formed by the merging side opening 17a of the EGR flow channel 17 and the intake downstream side 2b of the intake flow channel 2 is scraped to remove both the flow channels 17a, 2b. Are diagonally and smoothly connected to each other, but have a shape like this.

And by providing this combined flow path C1, the flow path configuration in the valve housing VH is set to the following flow area.
In the intake flow path 2, the effective maximum flow area of the intake flow path 2 is when the flow area on the intake upstream side 2a is utilized to the maximum, and when the valve body 20a of the intake throttle valve 20 is in the fully open position. This corresponds to the maximum effective flow area on the intake upstream side 2a of the engine, and is referred to as S. On the other hand, the maximum effective flow area of the EGR flow path 17 is a case where the opening area of the merging side opening 17a is utilized to the maximum, and the valve opening area when the valve body 18a of the EGR valve 18 is fully opened ( R1 + R2), but when the intake throttle valve 20 is fully opened, the valve body 20a is completely opposed to the merging side opening 17a of the EGR flow path 17, so that the intake throttle valve 20 is restricted to the fully open position. It will be. Therefore, the flow area formed by the peripheral edge of the lower surface of the valve body 20a of the intake throttle valve 20 (the surface facing the EGR flow path 17) and the merging side opening 17a of the EGR flow path 17 is defined as the minimum effective flow area T. When called, the combined flow path C1 (enlarged flow path portion CX) is formed so as to satisfy the relationship of T ≧ S / 2.

  When the corner portion C0 indicated by the broken line exists, the effective flow area T0 of the EGR gas passing through the intake throttle valve 20 when the intake throttle valve 20 is fully opened takes into account the intake passage at the maximum in consideration of the plate thickness of the valve body 20a and the like. The effective maximum distribution area S of 2 was less than 1/2 (T0 <S / 2).

  Here, supplementing the magnitude relationship of S, T, and (R1 + R2) that determines the flow area, which is the key of the present invention, in the case of a general EGR device, the flow area of the intake flow path 2 is equal to the EGR flow path 17. Since it is sufficiently large with respect to the distribution area of S and has a relationship of S> 2 × (R1 + R2), T ≧ S / 2 is set as described above. For example, the distribution area of both is S <2 × ( In the case of an inverse relationship such as (R1 + R2), it is a matter of course that T ≧ (R1 + R2) is set regardless of the flow area of the intake flow path 2.

  Thus, by providing the merge channel C1, when the EGR valve 18 is in the fully opened position when the intake throttle valve 20 is fully opened, the EGR gas flowing out from the merge side opening 17a of the EGR channel 17 to the merge portion C Can be supplied to the intake downstream side 2b by making maximum use of the minimum effective flow area T (avoid interference with the valve body 20a of the intake throttle valve 20).

[Effect of this embodiment]
The EGR device is typically used in an operation region in which the output performance of the engine 1 can be sacrificed. As described above, the EGR valve 18 is changed from the desired intermediate opening shown in FIG. The intake throttle valve 20 is driven to the fully closed position when rotating to the fully open position shown in the drawing. However, in recent years, the engine 1 is secured with high output performance, that is, with the intake throttle valve 20 fully opened. A special operation region for recirculating the maximum amount of EGR gas has appeared.
In such a special operation region, the EGR valve device (EGR valve unit U) configured as described above has the following operational effects.
(1) When the intake throttle valve 20 is fully opened, the effective flow area of the EGR gas passing therethrough (the lower peripheral edge of the valve body 20a of the intake throttle valve 20 and the merging side opening 17a of the EGR flow path 17) 2 can be ensured at least as a distribution area T (≧ S / 2) larger than T0, so that, for example, the desired intermediate opening degree of FIG. Even in the range from the position to the fully open position in FIG. 1, a desired amount of EGR gas can be recirculated as indicated by the white arrow.

(2) In particular, an inclined combined flow path C1 is adopted as the expanded flow path section CX, and the combined flow section C1 is connected to both related flow paths, that is, the merge-side opening 17a of the EGR flow path 17 and the intake air flow. Since the intake downstream side 2b of the passage 2 is connected smoothly and diagonally, the flow of the EGR gas becomes smooth (flow resistance is reduced), and the amount of recirculation of the EGR gas can be increased.
(3) It is a simple configuration in which an inclined combined channel C1 is added to the valve housing VH as the expanded channel CX, and a compact one unit can be realized as an EGR valve device.

[Method of manufacturing valve housing VH]
Next, an example of a method for manufacturing the valve housing VH according to the first embodiment will be described with reference to FIG.
The valve housing VH has a T-shape as a whole, and is a molded product formed of a molding material. As a molding material of the material, a light alloy such as an aluminum alloy or a heat resistant resin such as a polyimide resin is used. It is used and produced by molding means such as die casting (mold casting) or injection molding.
In the present embodiment, the expanded flow path portion CX is provided as the internal flow path configuration, but since the expanded flow path portion CX is formed by the inclined combined flow path C1, no matter which molding means is adopted, As shown by three types of hatching X, Y, and Z in FIG. 3, the three connection ports VH1 to VH3, that is, T-shaped three directions can be punched out.
Therefore, no special processing such as cutting is required to provide the enlarged flow path portion CX (inclined combined flow path C1).

[Example 2]
Next, a second embodiment of the present invention will be described based on FIG. 4 with a focus on differences from the first embodiment.
In the first embodiment, the merging side opening 17a of the EGR channel 17 is connected to the intake downstream side as the enlarged channel CX connecting the merging side opening 17a of the EGR channel 17 and the intake downstream side 2b of the intake channel 2 to each other. The inclined joint channel C1 that communicates with the intake downstream side 2b of the intake channel 2 while being expanded toward the side 2b is adopted. In this second embodiment, however, the assembly means of the valve housing VH is the pipe fitting method. This is an example of application suitable for the flange fastening method.

As shown in FIG. 4, the valve housing VH is provided with a flange VF at the connection port VH2 on the engine 1 side, and a pipe (pipe on the suction side of the compressor 5 in FIG. 5) P is connected from the engine 1 by this flange VF. It is fastened with the flange PF.
In this embodiment, an expanded diameter flow path C2 is provided as an expanded flow path portion CX that connects the merge side opening 17a of the EGR flow path 17 and the intake downstream side 2b of the intake flow path 2.
The expanded diameter combined flow path C2 makes the entire intake downstream side 2b of the intake passage 2 a large diameter portion C21 having a diameter larger than the intake upstream side 2a by a predetermined amount Q, and also opens the merge side opening of the EGR flow path 17. A notch C22 is provided in the portion 17a, and the confluence side opening 17a of the EGR flow path 17 and the intake downstream side 2b of the intake flow path 2 are connected stepwise.
Note that (R1 + R2) indicates the valve opening area when the valve element 18a of the EGR valve 18 is in the fully open position.
Thus, the minimum effective flow area T formed between the fully opened position of the intake throttle valve 20 and the merge side opening 17a of the EGR flow path 17 is equal to or greater than the valve area (R1 + R2), or the intake flow path 2 is effective. It is set to 1/2 or more of the maximum distribution area S.

According to the above configuration, when the intake throttle valve 20 is fully opened, the effective flow area of the EGR gas passing therethrough (the lower peripheral edge of the valve body 20a of the intake throttle valve 20 and the merging side opening of the EGR flow path 17) 17a), the flow area T [T ≧ (R1 + R2) or T ≧ S / 2] larger than T0 can be secured at least, so that the EGR valve 18 is set to the fully open position. The desired EGR gas can be refluxed.
In addition, since the entire intake downstream side 2b of the intake passage 2 is merely the large-diameter portion C21, the valve housing VH can be die-cut from the three connection ports VH1 to VH3, that is, three T-shaped directions. it can.
Therefore, also in the present embodiment, the same effect as in the first embodiment can be obtained.
According to the present embodiment, the flow area of the enlarged flow path portion CX can be freely selected by adjusting the diameter (expansion amount Q) of the connection port VH2, and the diameter of the connection port VH2 and the pipe P Can be adjusted by the flanges VF and PF, so that the degree of freedom in designing the flow area of the enlarged flow path portion CX is improved.

[Modification]
Although the embodiment of the present invention has been described in detail with reference to two examples, various modifications can be made without departing from the spirit of the present invention, and modifications thereof will be exemplified.

(1) In the first and second embodiments, the EGR flow path 17 is formed in a normal T shape that merges at a right angle to the intake flow path 2, but the EGR flow path 17 merges obliquely as shown in FIG. An irregular T-shaped type may be used, and this irregular T-shaped type is also included in the “T-shaped” recited in the claims of the present invention.
(2) In the second embodiment, the enlarged diameter confluence portion C2 is provided by forming the entire intake downstream side 2b of the intake passage 2 in the large diameter portion C21, but the intake downstream of the same diameter as the intake upstream side 2a. You may make it the dharma type which additionally formed the diameter-expanded part of the cross-sectional U character made to bulge only the predetermined amount Q on the side 2b.

(3) In the present embodiment, the present invention is applied to the low pressure side EGR device. However, when the high pressure side EGR device is also equipped with an intake throttle valve, the EGR valve device of the present invention is similarly applied. Can do.
(4) Further, in the present embodiment, an example in which the EGR valve device of the present invention is applied to the engine 1 in which the turbocharger is mounted in the intake and exhaust systems has been shown. However, the present invention is not limited to the turbocharger. The present invention can also be applied to the engine 1 equipped with a supercharger that drives the compressor 5 disposed in the passage 2 by the engine 1. In this case, the upstream end of the low pressure RGR passage 17 (intake of the low pressure EGR gas) is connected to the exhaust passage 3 downstream of the exhaust purification device (DPF 11 in the first embodiment), and the exhaust gas purified by the exhaust purification device. Part of the gas flows back to the intake passage 2 as low-pressure EGR gas.

  The features and effects of the present invention that have been described in detail above are summarized and listed from both the structural and method aspects according to the respective means described as the dependent claims in the claims. .

(Feature 1 = Means of claim 3)
3. The EGR valve device according to claim 1, wherein the expanded flow path portion CX has a merge side opening 17 a of the EGR flow path 17 on the intake downstream side 2 b from the position where the intake throttle valve 20 is disposed in the merge section C. The first embodiment is characterized in that it is formed by an inclined combined flow path C1 that is connected to the intake downstream side 2b of the intake flow path 2 while being expanded toward the intake downstream side 2b (Example 1).
According to the above means, in particular, the inclined joining channel C1 is adopted, and this joining part C1 is the two related passages, that is, the joining side opening 17a of the EGR passage 17 and the intake air of the intake passage 2. Since the downstream side 2b is connected obliquely and smoothly, the flow of EGR gas becomes smooth, and the amount of reflux of EGR gas can be increased.

(Feature point 2 = Means of claim 4)
3. The EGR valve device according to claim 1, wherein the expanded flow path portion CX is connected to the intake downstream side 2 b from the position where the intake throttle valve 20 is disposed in the merging portion C, and the intake downstream side flow path disconnection of the intake flow path 2. The area is enlarged, and it is characterized in that it is formed by an enlarged diameter confluence passage C2 that connects the confluence side opening 17a of the EGR passage 17 and the intake downstream side 2b of the intake passage 2 in a stepwise manner ( Example 2).
According to the above means, in particular, the enlarged diameter confluence channel C2 is employed, and this confluence portion C2 is formed by both related flow passages, that is, the confluence side opening 17a of the EGR flow passage 17 and the intake flow passage 2. Since the intake downstream side 2b is connected stepwise, the flow area of the combined flow path C2 can be freely selected by adjusting the diameter expansion amount Q, and the degree of freedom in design increases.

(Feature point 3 = Means of claim 5)
5. The EGR valve device according to claim 3, wherein the valve housing VH is a molded product formed in a T shape from a molding material, and is manufactured by being die-cut from three directions of the T shape. It is a feature.
According to the above means, no special processing such as cutting is required in order to provide the enlarged flow path portion CX (inclined combined flow path C1, expanded diameter combined flow path C2).

  DESCRIPTION OF SYMBOLS 1 ... Engine (internal combustion engine), 2 ... Intake flow path, 2a ... Intake upstream side, 2b ... Intake downstream side, 17 ... Low-pressure EGR flow path (EGR flow path), 17a ... Confluence side opening, 18 ... EGR valve, DESCRIPTION OF SYMBOLS 20 ... Intake throttle valve, C ... Merging part, CX ... Enlarged flow path part, R1, R2 ... Valve opening area, S ... Maximum effective flow area, T ... Minimum effective flow area, U ... EGR valve unit (EGR valve device) , VH: Valve housing.

Claims (5)

An intake passage (2) for supplying intake air to the internal combustion engine (1), an EGR passage (17) for guiding exhaust gas of the internal combustion engine (1) as EGR gas to the intake passage (2), and the intake air A valve housing (VH) having a merging portion (C) for joining the EGR flow path (17) in a T shape between the intake upstream side (2a) and the intake downstream side (2b) in the flow path (2). When,
An EGR valve (18) that is provided in the valve housing (VH) and adjusts the opening of the EGR flow path (17);
An intake throttle valve (20) that is disposed in the merging portion (C), adjusts the opening of the intake passage (2), and generates an intake negative pressure in the merging portion (C);
With
The valve housing (VH) has a fully opened position of the intake throttle valve (20) and the EGR flow path on the downstream side (2b) of the intake throttle valve (20) in the merging portion (C). The minimum effective flow area (T) formed between the merging side opening (17a) of (17) is the maximum effective flow area of the intake flow path (2) when the intake throttle valve (20) is fully opened. An EGR valve device having an enlarged flow path portion (CX) that is ½ or more of (S). An intake passage (2) for supplying intake air to the internal combustion engine (1), an EGR passage (17) for guiding exhaust gas of the internal combustion engine (1) as EGR gas to the intake passage (2), and the intake air A valve housing (VH) having a merging portion (C) for joining the EGR flow path (17) in a T shape between the intake upstream side (2a) and the intake downstream side (2b) in the flow path (2). When,
An EGR valve (18) that is provided in the valve housing (VH) and adjusts the opening of the EGR flow path (17);
An intake throttle valve (20) that is disposed in the merging portion (C), adjusts the opening of the intake passage (2), and generates an intake negative pressure in the merging portion (C);
With
The valve housing (VH) has a fully opened position of the intake throttle valve (20) and the EGR flow path on the downstream side (2b) of the intake throttle valve (20) in the merging portion (C). The minimum effective flow area (T) formed between the merging side opening (17a) of (17) is defined as the valve opening area (R1 + R2) of the EGR flow path (17) when the EGR valve (18) is fully opened. ) An EGR valve device having an enlarged flow path portion (CX) that expands as described above. The EGR valve device according to claim 1 or 2,
The enlarged flow path portion (CX) is formed on the merging side opening (of the EGR flow path (17)) on the intake downstream side (2b) from the arrangement position of the intake throttle valve (20) in the merging portion (C). and characterized in that it is formed by 17a) intake downstream (inclined in the combined channel to be connected to the intake downstream side (2b) of the intake passage while expanding toward 2b) (2) (C1) EGR valve device. The EGR valve device according to claim 1 or 2,
The enlarged flow path portion (CX) is a flow path on the intake downstream side of the intake flow path (2) on the intake downstream side (2b) from the arrangement position of the intake throttle valve (20) in the merging section (C). A cross-sectional area is enlarged, and the diameter-increased combined flow path (steps) connecting the confluence-side opening (17a) of the EGR flow path (17) and the intake downstream side (2b) of the intake flow path (2) in steps. The EGR valve device is formed by C2). The EGR valve device according to claim 3 or 4,
The valve housing (VH) is a molded product formed in a T shape from a molding material,
An EGR valve device, wherein the EGR valve device is manufactured by being die-cut from three T-shaped directions.