JP4840282B2 - Exhaust gas switching valve - Google Patents

Description

  The present invention relates to an exhaust gas switching valve incorporated in an exhaust gas recirculation device that recirculates exhaust gas of an internal combustion engine from an exhaust passage to an intake passage, and in particular, a cooled mode in which the exhaust gas of the internal combustion engine passes through an exhaust gas cooler and the internal combustion engine. The present invention relates to an exhaust gas switching valve that switches an engine exhaust gas to a hot mode that bypasses an exhaust gas cooler.

[Conventional technology]
Conventionally, an exhaust gas recirculation device (EGR system) for recirculating exhaust gas of an internal combustion engine from an exhaust passage to an intake passage is known. In this EGR system, a water-cooled exhaust gas cooler (EGR cooler) is installed in the middle of an exhaust gas recirculation pipe (EGR pipe) that recirculates exhaust gas (EGR gas) from an exhaust passage to an intake passage. Thereby, the combustion temperature of the engine can be lowered without reducing the output of the engine, and the amount of harmful substances (for example, NOx) contained in the exhaust gas can be reduced.

  In addition, the EGR system with an EGR cooler bypasses the EGR gas from the EGR cooler and returns it to the intake passage for the purpose of improving combustion when the temperature of the cooling water is low, such as when the engine is started or in winter. In such an EGR system, a bypass flow path for bypassing EGR gas flowing into the valve housing chamber from the EGR cooler and returning it to the intake passage is provided inside the housing having a cooler mounting surface for mounting the EGR cooler. A bypass switching valve that is formed and rotatably accommodates a bypass switching valve that opens and closes the bypass flow path is provided inside the valve storage chamber (see, for example, Patent Document 1).

Here, FIG. 4 is a diagram showing an EGR gas cooling device in which a general bypass switching valve and an EGR cooler are integrated.
This EGR gas cooling device includes a water-cooled EGR cooler 101 that cools EGR gas that recirculates from the exhaust passage of the internal combustion engine to the intake passage, and a cooled gas (cooler) for improving the emission performance of the internal combustion engine and stabilizing the combustion state. ) Mode and a hot gas (cooler bypass) mode.
The bypass switching valve 102 includes a housing 103 coupled and integrated with the EGR cooler 101, a valve 104 rotatably accommodated in the housing 103, a rotating shaft 105 that supports and fixes the valve 104, and the rotation And an actuator (not shown) for driving the valve 104 via the shaft 105.

On each coupling surface and cooler mounting surface of the housing 103, four exhaust gas ports including an EGR gas introduction port 111, a cooler inlet port 112, a cooler outlet port 113, and an EGR gas outlet port 114 are opened.
Here, in the cooler mode, as shown in FIG. 4, the first EGR gas passage 106 communicating the EGR gas introduction port 111 and the cooler inlet port 112, and the cooler outlet port 113 and the EGR gas outlet port 114 are communicated. A second EGR gas passage 107 is formed inside the housing 103. As a result, in an operation state where an EGR gas having a low temperature is required (an operation state of the internal combustion engine), the cooling water and heat are passed through the EGR cooler 101 by switching the interior (flow path) of the housing 103 to the cooler mode. The low-temperature EGR gas (cooled EGR gas) that has been exchanged and cooled to a predetermined gas temperature or lower can be recirculated to the intake passage.
In the cooler bypass mode, a bypass passage (not shown) that connects the EGR gas inlet port 111 and the EGR gas outlet port 114 is formed inside the housing 103. As a result, in an operation state where an EGR gas having a high temperature is required (an operation state of the internal combustion engine), by switching the inside (flow path) of the housing 103 to the cooler bypass mode, the high-temperature EGR gas that does not pass through the EGR cooler 101 ( Hot EGR gas) can be recirculated to the intake passage.

[Conventional technical problems]
However, in the conventionally known bypass switching valve (described in Patent Document 1) and the bypass switching valve 102 shown in FIG. 4, the switching operation is stably performed under all temperature conditions, and an assembly error is absorbed. A gap (clearance) is provided between the peripheral edge of the opening of the housing 103 and the periphery of the valve 104.
In the cooler mode, the differential pressure across the EGR cooler 101 is applied to both end faces and gaps in the plate thickness direction of the valve 104. Due to the differential pressure across the EGR cooler 101, hot EGR gas flowing through the first EGR gas passage 106 leaks through the gap to the second EGR gas passage 107 side.
That is, when the hot EGR gas leaks to the second EGR gas passage 107 side, the hot EGR gas is mixed with the cooled EGR gas flowing in from the EGR cooler 101, and the cooled EGR gas flowing out from the EGR gas outlet port 114 of the housing 103 into the intake passage. The temperature will rise. Therefore, since the cooling efficiency of the EGR gas in the EGR gas cooling device is lowered, there arises a problem that the emission performance is lowered.

In addition, in order to suppress (compensate) a decrease in cooling efficiency of the EGR gas cooling device due to leakage of high temperature EGR gas (hot EGR gas), the heat radiation area of the EGR cooler 101 is increased to improve the performance of the EGR cooler 101. In addition, installing a radiator different from the engine cooling water radiator and lowering the cooling water supplied to the EGR cooler 101 at a lower temperature to improve the performance of the EGR cooler 101 Deterioration in mounting ability and cost increase are required.
Japanese Patent Laid-Open No. 2007-100522

  An object of the present invention is to suppress an increase in the temperature of exhaust gas due to leakage of high-temperature exhaust gas from the first gas passage to the second gas passage in the cooler mode while suppressing deterioration in mountability and cost increase in the vehicle. Thus, an object of the present invention is to provide an exhaust gas switching valve that can suppress a decrease in emission performance.

According to the first aspect of the present invention, even when the high-temperature exhaust gas leaks from the first gas passage through the gap formed between the housing and the valve to the second gas passage side in the cooler mode, By providing the heat absorption part exposed at the wall surface of the second gas passage of the housing, the heat of the exhaust gas that has flowed into the second gas passage, in particular, leaked from the first gas passage to the second gas passage side in the cooler mode. The heat of the high-temperature exhaust gas can be absorbed by a cooling fluid such as cooling water whose temperature is extremely lower than that of the exhaust gas. As a result, the temperature of the exhaust gas flowing into the second gas passage, that is, the exhaust gas that has risen due to the leak of hot exhaust gas from the first gas passage to the second gas passage in the cooler mode (from the outlet of the exhaust gas cooler). The temperature of the exhaust gas flowing into the second gas passage can be lowered.
Therefore, it is possible to suppress an increase in the temperature of exhaust gas due to leakage of high-temperature exhaust gas from the first gas passage to the second gas passage in the cooler mode, while suppressing deterioration in mountability and cost increase in the vehicle. It is possible to suppress a decrease in emission performance.
In addition, since it is possible to compensate for a decrease in cooling efficiency due to high temperature exhaust gas leakage in the exhaust gas switching valve, it is possible to improve the cooling performance of the exhaust gas cooling device that combines the exhaust gas cooler and the exhaust gas switching valve. Become. In addition, since the cooling efficiency in the exhaust gas cooling device can be increased, it is possible to improve the emission performance at a low cost.
Furthermore, according to the first aspect of the present invention, the heat absorption part of the housing is installed closer to the cooler outlet port than the valve in the bypass mode, so that the heat of the high-temperature exhaust gas is absorbed by the heat absorption part. There is nothing. As a result, even when the heat absorption part is provided in the housing, the high-temperature exhaust gas can be recirculated to the intake passage of the internal combustion engine, so that the combustion state of the internal combustion engine becomes unstable or the emission performance deteriorates. There is nothing to do.

According to the second aspect of the present invention, in the cooler mode, the first gas passage that communicates the gas introduction port and the cooler inlet port, and the second gas passage that communicates the cooler outlet port and the gas outlet port are provided in the housing. Formed inside.
According to the third aspect of the present invention, the valve functions as a partition plate that partitions the interior (flow path) of the housing into the first gas passage and the second gas passage in the cooler mode.
According to the second and third aspects of the present invention, the exhaust gas that has flowed from the exhaust passage of the internal combustion engine through the gas introduction port into the housing (first gas passage) flows from the cooler inlet port to the inside of the exhaust gas cooler. It is introduced and cooled. Then, the exhaust gas that has flowed into the housing (second gas passage) from the outlet of the exhaust gas cooler through the cooler outlet port flows out of the gas outlet port. Thereby, since the exhaust gas recirculated to the intake passage of the internal combustion engine can be cooled by the exhaust gas cooler, the charging efficiency of the exhaust gas into the internal combustion engine is increased, and the emission performance can be improved.

According to the fourth aspect of the present invention, the housing has a bypass passage that communicates the gas introduction port and the gas outlet port.
According to the fifth aspect of the present invention, at least the bypass passage is formed inside the housing in the bypass mode.
According to the sixth aspect of the present invention, the valve functions as a partition plate that partitions the interior (flow path) of the housing into the bypass passage, the cooler inlet port, and the cooler outlet port in the bypass mode. .
According to the fourth to sixth aspects of the present invention, the exhaust gas flowing into the housing (bypass passage) from the exhaust passage of the internal combustion engine through the gas introduction port bypasses the exhaust gas cooler and is discharged from the gas outlet port. leak. As a result, the exhaust gas recirculated to the intake passage of the internal combustion engine can be bypassed from the exhaust gas cooler, so that a sufficient warming effect on the intake air supplied to the internal combustion engine can be obtained, and the combustion state of the internal combustion engine can be reduced. Stable and can prevent deterioration of emission performance.

According to the invention described in claim 7, the heat absorption area of the heat absorption part is increased by providing the heat absorption part with the cooling fin so as to protrude from the wall surface of the second gas path toward the second gas path. Therefore, when the exhaust gas passes through the second gas passage, it can be efficiently cooled by the cooling fluid.

According to the eighth aspect of the invention, the cooling fluid is cooling water for cooling the internal combustion engine. A cooling water passage through which cooling water for cooling the internal combustion engine flows is formed inside the housing.
According to the ninth aspect of the present invention, the cooling fluid is cooling water flowing into the exhaust gas cooler. A cooling water passage through which cooling water flowing into the exhaust gas cooler flows is formed inside the housing.
According to the invention described in claim 10, the cooling water passage through which the cooling water flows is formed inside the housing wall portion of the housing (the housing outer wall portion that partitions the second gas passage and the outside of the housing).
According to the invention described in claims 8 to 10, since the exhaust gas flowing into the second gas passage is efficiently cooled (water-cooled) by the cooling water having an extremely low temperature compared to the exhaust gas, the second Decreasing the temperature of the exhaust gas flowing into the gas passage, that is, the temperature of the exhaust gas flowing through the second gas passage that has risen due to leakage of the hot exhaust gas from the first gas passage to the second gas passage in the cooler mode. Can do.

According to the eleventh aspect of the present invention, the heat absorbing portion is exposed at the second gas passage wall surface of the housing wall portion of the housing (the housing outer wall portion that partitions the second gas passage and the outside of the housing). As a result, the heat of the exhaust gas flowing into the second gas passage, particularly the heat of the high-temperature exhaust gas leaking from the first gas passage to the second gas passage side in the cooler mode, is extremely high compared to the exhaust gas, for example. Heat can be absorbed by a cooling fluid such as low cooling water. As a result, the temperature of the exhaust gas flowing into the second gas passage, that is, the exhaust gas that has risen due to the leak of hot exhaust gas from the first gas passage to the second gas passage in the cooler mode (from the outlet of the exhaust gas cooler). The temperature of the exhaust gas flowing into the second gas passage can be lowered.
According to the twelfth aspect of the present invention, the heat sink is provided with the cooling fin so as to protrude from the second gas passage wall surface of the housing wall portion of the housing toward the second gas passage. Since the heat absorption area increases, the exhaust gas can be efficiently cooled by the cooling fluid when passing through the second gas passage.

  The best mode for carrying out the present invention is exhaust by leakage of high-temperature exhaust gas from the first gas passage to the second gas passage in the cooler mode while suppressing deterioration in mountability to vehicles and cost increase. The passage of the second gas passage of the housing is designed so that the heat of the exhaust gas that has flowed into the second gas passage can be absorbed by the cooling water for the purpose of suppressing the deterioration of the emission performance by suppressing the temperature rise of the gas. This was realized by providing an endothermic part exposed at the wall surface (the second gas passage wall surface of the housing wall).

[Configuration of Example 1]
FIGS. 1 to 3 show Example 1 of the present invention, FIG. 1 is a view showing a bypass fully closed position in a cooler mode (cooled mode), and FIG. 2 is a view showing a valve unit. FIG. 3 is a diagram showing the bypass fully open position in the bypass mode (hot mode).

An exhaust gas recirculation device (EGR system) for an internal combustion engine according to this embodiment is configured such that a part of exhaust gas (hereinafter referred to as EGR gas) of an internal combustion engine (hereinafter referred to as engine) such as a diesel engine is changed from an exhaust passage to an intake passage. An exhaust gas recirculation pipe (EGR pipe) for recirculation and an EGR cooler module installed in the middle of the EGR pipe are provided.
The EGR cooler module includes an exhaust gas cooling device (EGR gas cooling device) that cools EGR gas that recirculates from the exhaust passage to the intake passage, and an exhaust gas that controls the flow rate and temperature of the EGR gas that recirculates from the exhaust passage to the intake passage. A control device (EGR gas control device) is included.

The EGR cooler module is formed by combining and integrating an EGR cooler 1 as an exhaust gas cooler and a valve unit 2 including two first and second exhaust gas control valves that control the flow rate and temperature of EGR gas.
The valve unit 2 includes a common housing 3 for the two first and second exhaust gas control valves. Inside the housing 3, as shown in FIG. 1, two first and second EGR gas passages 11 and 12 are formed in the cooled mode. Further, as shown in FIG. 3, a bypass passage 13 (and a cooler side closed space 14) is formed inside the housing 3 in the hot mode.

Here, the exhaust gas passages (the two first and second EGR gas passages 11 and 12) return the EGR gas that has flowed into the housing 3 from the exhaust passage through the EGR cooler 1 to the intake passage. This is the main flow path (main route).
The exhaust gas passage (bypass passage 13) is a bypass passage (bypass route) that bypasses the EGR cooler 1 and recirculates the EGR gas flowing into the housing 3 from the exhaust passage to the intake passage. .
Details of the housing 3 will be described later.

The first exhaust gas control valve is an exhaust gas flow rate control valve (EGR gas flow rate control) that controls the flow rate of EGR gas that flows through an exhaust gas passage (second EGR gas passage 12 or bypass passage 13) formed inside the housing 3. Valve: hereinafter referred to as EGRV).
The EGRV of the present embodiment is installed (mounted) in the housing 3 common to the second exhaust gas control valve, and the first valve (in particular, the second EGR gas passage 12) inserted in the exhaust gas passage of the housing 3 ( An EGR gas flow control valve (hereinafter referred to as a flow control valve), a first rotating shaft (valve shaft) that supports and fixes the flow control valve, and a first actuator that drives the flow control valve via the valve shaft. I have.

The second exhaust gas control valve is an exhaust gas switching that controls the temperature of the EGR gas flowing through the exhaust gas passages (two first and second EGR gas passages 11 and 12 or the bypass passage 13) formed in the housing 3. It is a valve (hereinafter referred to as an EGR gas switching valve).
The EGR gas switching valve of the present embodiment is installed (mounted) in the housing 3 common to EGRV, and is inserted into the housing 3 (upstream in the EGR gas flow direction (EGR cooler side) with respect to EGRV). One four-way switching valve 4, a second rotating shaft (valve shaft) 5 that supports and fixes the four-way switching valve 4, and a second actuator that drives the four-way switching valve 4 via the valve shaft 5 It has.
Details of the EGR gas switching valve will be described later.
Here, in this embodiment, the valve unit 2 is constituted by the housing 3, the EGRV, and the EGR gas switching valve.

The EGR cooler 1 is a water-cooled exhaust gas cooler that cools the EGR gas to a desired exhaust temperature or less by exchanging heat between the engine cooling water flowing from the water jacket of the engine and the EGR gas. Airtightly coupled to.
The EGR cooler 1 has a rectangular tube-shaped casing that is open on one side in the central axis direction, and a laminated core portion in which a plurality of flat tubes through which EGR gas flows are stacked in the thickness direction. . An offset type inner fin for enhancing heat exchange performance is inserted in each flat tube. And in each flat tube, the U-shaped EGR gas flow path which connected two parallel flow paths with the U-shaped part is formed.

The laminated core portion of the EGR cooler 1 is partitioned into two first and second laminated core portions 21 and 22 by a partition wall 20. Inside the casing of the EGR cooler 1, there are an inlet side tank chamber (an inlet of the EGR cooler 1) 23 communicating with the upstream side of the first laminated core portion 21 in the EGR gas flow direction, and the EGR of the second laminated core portion 22. An outlet side tank chamber (exit of the EGR cooler 1) 24 that communicates with the downstream side in the gas flow direction and an intermediate tank chamber 25 that communicates the two first and second laminated core portions 21 and 22 are formed.
Further, the EGR cooler 1 has a plurality of cooling water flow paths through which engine cooling water circulates around the plurality of flat tubes constituting the first and second laminated core portions 21 and 22. Yes.

The casing of the EGR cooler 1 is connected to an inlet pipe for flowing engine cooling water into the plurality of cooling water flow paths and an outlet pipe for flowing engine cooling water from the plurality of cooling water flow paths. Yes.
And the coupling | bond part which has a coupling surface (housing mounting surface) couple | bonded with the cooler mounting surface of the housing 3 is integrally provided in the housing side edge part of the casing. An exhaust gas inflow port (EGR gas inflow port) of the inlet side tank chamber 23 and an exhaust gas outflow port (EGR gas outflow port) of the outlet side tank chamber 24 are opened on the housing mounting surface.

In addition, a flange portion 26 is integrally formed at the coupling portion of the casing so as to project beyond the outer wall surface of the casing. The flange portion 26 has a plurality of bolt holes through which fastening bolts are inserted.
The EGR cooler 1 is coupled (fastened) to the cooler mounting surface of the housing 3 using a plurality of fastening bolts in a state where the housing mounting surface of the coupling portion of the casing and the cooler mounting surface of the housing 3 are in close contact with each other. Has been.
Note that a sealing material such as a gasket or packing is used between the housing mounting surface of the flange portion 26 of the EGR cooler 1 and the cooler mounting surface of the flange portion 27 of the housing 3 to prevent leakage of EGR gas to the outside. You may disguise.

The housing 3 of the valve unit 2 of the present embodiment is integrally formed in a predetermined shape with a metal material (for example, iron-based casting (cast iron) or aluminum die casting). The housing 3 is connected in the middle of the EGR pipe, and one hollow portion (valve accommodating chamber) is formed inside. And the cooler attachment surface which attaches the coupling | bond part (flange part 26) of the EGR cooler 1 is formed in the flange part 27 of the housing 3. As shown in FIG. The flange portion 27 has a plurality of screw holes into which fastening bolts are screwed.
Further, the housing 3 of the present embodiment has a cylindrical first coupling portion 28 that protrudes upstream in the EGR gas flow direction (exhaust passage side), and protrudes downstream in the EGR gas flow direction (intake passage side). The cylindrical second coupling portion 29 is integrally formed.
The first coupling portion 28 is attached to the EGR pipe (or the branch portion of the exhaust pipe of the engine, particularly the branch portion of the exhaust manifold), which is a pipe on the exhaust passage side, upstream of the valve housing chamber in the EGR gas flow direction. A first coupling surface is provided.
The second coupling portion 29 is attached to an EGR pipe (or a merge portion of the intake pipe of the engine, particularly a merge portion of the intake manifold), which is a pipe on the intake passage side, downstream of the valve housing chamber in the EGR gas flow direction. A second coupling surface is provided.

The housing 3 has four first to fourth exhaust gas ports connected to the exhaust passage and the intake passage of the engine and the inlet side tank chamber 23 and the outlet side tank chamber 24 of the EGR cooler 1, respectively. Note that these four exhaust gas ports communicate with a valve housing chamber formed inside the housing 3.
The four first to fourth exhaust gas ports communicate with the EGR gas introduction port 31 that communicates with the exhaust passage of the engine, the EGR gas lead-out port 32 that communicates with the intake passage of the engine, and the inlet side tank chamber 23 of the EGR cooler 1. The cooler inlet port 33 and the cooler outlet port 34 communicating with the outlet side tank chamber 24 of the EGR cooler 1 are configured.
The EGR gas introduction port 31 opens on the first coupling surface formed in the first coupling portion 28 of the housing 3. Further, the EGR gas outlet port 32 opens on the second coupling surface formed in the second coupling portion 29 of the housing 3. The cooler inlet port 33 and the cooler outlet port 34 are adjacently opened on the cooler mounting surface of the flange portion 27 of the housing 3.

As shown in FIG. 1, the first EGR gas passage 11 connects the EGR gas introduction port 31 and the cooler inlet port 33, and hot EGR that has flowed into the housing 3 (valve housing chamber) from the exhaust passage of the engine. 1 is a first exhaust gas passage (cooler introduction passage) for introducing gas (high-temperature exhaust gas) into the EGR cooler 1.
As shown in FIG. 1, the second EGR gas passage 12 connects the cooler outlet port 34 and the EGR gas outlet port 32, and from the outlet side tank chamber 24 of the EGR cooler 1 to the inside of the housing 3 (valve housing chamber). 2 is a second exhaust gas passage (cooler derivation route) that recirculates the cooled EGR gas (low temperature exhaust gas) flowing into the engine to the intake passage of the engine. The second EGR gas passage 12 is inclined with respect to an axis passing through the center of the cooler outlet port 34 (a central axis of the cooler outlet port 34) from the vicinity of the cooler outlet port 34 to the vicinity of the EGR gas outlet port 32. Thus, an inclined passage that extends straightly in a straight line is formed.

As shown in FIG. 3, the bypass passage 13 communicates the EGR gas inlet port 31 and the EGR gas outlet port 32, and hot EGR gas that has flowed into the housing 3 (valve housing chamber) from the exhaust passage of the engine. This is a cooler bypass passage (cooler bypass route) that bypasses (high-temperature exhaust gas) from the EGR cooler 1 and recirculates it to the intake passage of the engine.
Here, the housing 3 has a housing outer wall portion 6 that partitions the second EGR gas passage 12 (cooler outlet port 34 and valve accommodating chamber) and the outside of the housing 3 between the flange portion 27 and the second coupling portion 29. is doing. The second EGR gas passage wall surface (passage wall surface) of the housing outer wall portion 6 is provided with a heat absorbing portion exposed on the passage wall surface of the second EGR gas passage 12 (housing outer wall portion 6).
The heat absorbing portion of the housing 3 is a rectangular annular shape described later from the low-temperature EGR gas (cooled EGR gas) flowing into the second EGR gas passage 12 from the outlet side tank chamber 24 of the EGR cooler 1 and the first EGR gas passage 11 in the cool mode. EGR gas cooling means (exhaust gas cooling means) provided at a portion where the EGR gas temperature rises due to mixing with high temperature EGR gas (hot EGR gas) leaking into the second EGR gas passage 12 through the clearance (clearance) It is.
The details of the heat absorbing portion of the housing 3 will be described later.

The four-way switching valve 4 is made of a metal material such as stainless steel having excellent heat resistance and corrosion resistance. The four-way switching valve 4 is rotatably accommodated in the valve accommodating chamber of the housing 3. Then, the four-way switching valve 4 arbitrarily switches the communication state between the exhaust gas ports in the four exhaust gas ports by rotating around the rotational axis of the valve shaft 5 in the valve accommodating chamber.
The four-way switching valve 4 is a single butterfly valve configured by a rectangular valve plate that extends toward both sides in the radial direction perpendicular to the rotational axis direction of the valve shaft 5. Further, the four-way switching valve 4 continuously variably adjusts the opening degrees of the two first and second EGR gas passages 11 and 12 and the opening degree of the bypass passage 13 according to the switching position thereof. The mixing ratio between the flow rate of the cooled EGR gas passing through the second EGR gas passages 11 and 12 and cooled by the EGR cooler 1 and the flow rate of the hot EGR gas passing through the bypass passage 13 and bypassing the EGR cooler 1 is arbitrarily changed. Thus, the temperature of the EGR gas returned to the intake passage can be controlled.

The four-way switching valve 4 has a function as a partition plate that partitions the inside (flow path) of the housing 3 into the first EGR gas passage 11 and the second EGR gas passage 12 in the cool mode (see FIG. 1). is doing. Thereby, when the communication state between the exhaust gas ports in the four exhaust gas ports is switched by the four-way switching valve 4, the two first and second EGR gas passages 11 and 12 are formed in the housing 3. .
In the hot mode (see FIG. 3), the four-way switching valve 4 allows the interior (flow path) of the housing 3 to be connected to the bypass passage 13, the cooler inlet port 33, and the cooler outlet port 34 (cooler side closed space 14). It functions as a partition plate for partitioning. Thus, when the communication state between the exhaust gas ports in the four exhaust gas ports is switched by the four-way switching valve 4, the bypass passage 13 is formed inside the housing 3.

Here, in the four-way switching valve 4 of the present embodiment, the switching position where the flow rate of the cooled EGR gas is maximized is the bypass fully closed position (cooled mode: see FIG. 1), and the switching where the flow rate of the hot EGR gas is maximized. When the position is the bypass fully open position (hot mode: see FIG. 3), the position can be continuously switched from the bypass fully closed position to the bypass fully open position. The four-way switching valve 4 may be set to an intermediate opening state between the bypass fully closed position and the bypass fully open position, that is, a mixing position for mixing the cooled EGR gas and the hot EGR gas.
The housing 3 of this embodiment is formed with a first opening 35 that is closed by the valve plate-like body of the four-way switching valve 4 in the cool mode. The housing 3 is also formed with a second opening 36 that is closed by the valve plate of the four-way switching valve 4 in the hot mode. Then, between the periphery of the valve plate-like body of the four-way switching valve 4 and the opening peripheral edge of the first opening 35 of the housing 3, and around the valve plate-like body of the four-way switching valve 4 and the housing 3. The two-way switching valve 4 can smoothly rotate within the valve housing chamber of the housing 3 without being affected by an assembly error or a difference in thermal expansion coefficient between the opening peripheral edge of the two openings 36. A square annular gap (clearance) is formed.

A valve shaft 5 of the EGR gas switching valve (four-way switching valve 4) is a cylindrical shaft formed of a metal material such as stainless steel having excellent heat resistance and corrosion resistance, and is formed in the housing 3. By passing through the communication hole, it is inserted straight from the outside of the housing 3 to the inside (valve housing chamber) along the axial direction of the communication hole. A four-way switching valve 4 is welded and fixed to the tip of the valve shaft 5 in the rotational axis direction.
The second actuator is a negative pressure actuated actuator that generates a driving force when a negative pressure lower than atmospheric pressure is introduced.

Here, the electric motor that is the power source of the first actuator of the EGRV, the negative pressure control valve that supplies the negative pressure that is the power source of the second actuator of the EGR gas switching valve to the negative pressure chamber, and the electric vacuum pump are the ECU Is configured to be energized.
Here, the ECU includes a CPU that performs control processing, arithmetic processing, a storage device (memory such as ROM and RAM) that stores various programs and data, an input circuit, an output circuit, and the like. A microcomputer having a structure is provided.

  In addition, when the ECU turns on an ignition switch (not shown), the ECU opens the EGRV flow control valve and the four-way switching valve 4 of the EGR gas switching valve based on a control program stored in the memory. Are configured to be electronically controlled. The ECU is configured to forcibly terminate the above control based on the control program stored in the memory when the ignition switch is turned off (IG / OFF). The sensor signals from the various sensors are A / D converted by an A / D converter and then input to a microcomputer built in the ECU. The microcomputer is connected to a crank angle sensor, an accelerator opening sensor, a cooling water temperature sensor, an intake air temperature sensor, an EGR gas flow rate sensor, an EGR gas temperature sensor, and the like.

As shown in FIGS. 1 to 3, the heat absorbing portion of the housing 3 of the present embodiment is configured such that the engine cooling water (cooling fluid) flows through the cooling water passage 7 using the heat of the EGR gas flowing into the second EGR gas passage 12. So as to be able to absorb heat. A plurality of cooling fins 9 are formed in a triangular shape in the heat absorbing portion of the housing 3 so as to protrude from the passage wall surface of the housing outer wall portion 6 into the second EGR gas passage 12.
The heat absorbing portion of the housing 3 has an inclined surface parallel to the rotation angle (inclination angle) in the valve housing chamber corresponding to the stop position (bypass fully closed position) of the valve plate-like body of the four-way switching valve 4 in the cool mode. Is provided. Further, the heat absorption part of the housing 3 is located on the cooler outlet port 34 side (second EGR side) from the valve plate-like body of the four-way switching valve 4 so as not to lower the temperature of the hot EGR gas passing through the bypass passage 13 in the hot mode. It is installed in the cooler side closed space 14 side that forms the gas passage 12.

  The cooling water passage 7 is formed inside a block 37 integrally provided on the outer wall surface of the housing outer wall portion 6 so as to protrude toward the opposite side to the second EGR gas passage side. Connected to the block 37 of the housing outer wall 6 are an inlet pipe for flowing engine cooling water into the cooling water passage 7 and an outlet pipe for letting engine cooling water out from the cooling water passage 7. Note that the outlet pipe of the housing 3 is connected to the inlet pipe of the EGR cooler 1 via a connecting pipe. That is, the engine cooling water flowing out from the engine radiator (or water jacket) is first introduced into the cooling water passage 7 of the exhaust gas switching valve and then introduced into the plurality of cooling water passages of the EGR cooler 1. Thereafter, the engine coolant is circulated and supplied to the water jacket (or radiator) of the engine.

[Operation of Example 1]
Next, the operation of the EGR cooler module incorporated in the EGR system of this embodiment will be briefly described with reference to FIGS.

When the ignition switch is turned on (IG / ON) and the engine is started, the ECU determines that the EGRV valve opening (actual EGR amount) detected by the EGR gas flow sensor corresponds to the engine operating state. The power supplied to the electric motor built in the first actuator is feedback-controlled so as to substantially coincide with the control target value (target EGR amount) set in the above.
When electric power is supplied to the electric motor, the driving force (motor output shaft torque) of the electric motor is transmitted to the valve shaft, and the EGRV flow control valve is driven to open from the fully closed position to the valve opening operation direction. The

  Accordingly, the flow control valve of the EGRV is controlled to open to a valve opening corresponding to the control target value against the biasing force of the spring. As a result, a part of the exhaust gas flowing out from the combustion chamber for each cylinder of the engine (for example, high temperature EGR gas: hot EGR gas of 500 ° C. or higher) is discharged from the exhaust passage formed in the exhaust pipe of the engine to the exhaust passage side. Exhaust gas recirculation path (EGR passage) formed in the EGR pipe, the inside of the housing 3 of the EGR cooler module (first EGR gas path 11), the inside of the EGR cooler 1 (U-shaped EGR gas flow path), EGR The intake passage formed in the intake pipe of the engine passes through the interior of the cooler module housing 3 (second EGR gas passage 12) and the exhaust gas recirculation passage (EGR passage) formed in the EGR pipe on the intake passage side. Recirculated (refluxed).

In addition, the ECU controls the negative pressure control valve and the electric vacuum pump so that the switching position of the four-way switching valve 4 of the EGR gas switching valve becomes the bypass fully closed position during medium-load and high-load operation of the engine. .
When the switching position of the four-way switching valve 4 is set to the bypass fully closed position, the internal flow path of the housing 3 is switched to the cooled mode. In this cool mode, as shown in FIG. 1, the EGR gas introduction port 31 → the first EGR gas passage 11 → the cooler inlet port 33 → the inside of the EGR cooler 1 (U-shaped EGR gas flow path: inlet side tank chamber 23 → the first laminated core portion 21 → the intermediate tank chamber 25 → the second laminated core portion 22 → the outlet side tank chamber 24) → the cooler outlet port 34 → the second EGR gas passage 12 → the EGR gas outlet port 32, Cooled EGR gas is recirculated to the intake passage of the engine.

As a result, the cooled EGR gas that has been sufficiently cooled when passing through the EGR cooler 1 during medium-load and high-load operation of the engine, that is, the cooled EGR gas having a low EGR gas temperature and a low density, enters the intake passage. Will be mixed into the intake air.
Thereby, the combustion temperature of the engine can be lowered without reducing the output of the engine, and the amount of harmful substances (for example, nitrogen oxide: NOx) contained in the exhaust gas can be reduced. In addition, by cooling the EGR gas returning to the intake passage by the EGR cooler 1, the charging efficiency of the EGR gas into the combustion chamber of the engine can be increased and the emission performance can be improved.

Further, the ECU controls the negative pressure control valve and the control valve so that the switching position of the four-way switching valve 4 of the EGR gas switching valve becomes the bypass fully opened position during cold start of the engine or low load operation (idle operation). Controls an electric vacuum pump.
When the switching position of the four-way switching valve 4 is set to the bypass fully open position, the internal flow path of the housing 3 is switched to the hot mode. In this hot mode, as shown in FIG. 3, the hot EGR gas is recirculated to the intake passage of the engine via the EGR gas introduction port 31 → the bypass passage 13 → the EGR gas outlet port 32.
This makes it possible to obtain a sufficient warming effect on the intake air during cold start of the engine or during low load operation (idle operation), improving the flammability in the engine, and hydrocarbon (hydrocarbon: HC) and white smoke can be prevented.

[Effect of Example 1]
As described above, in the EGR cooler module incorporated in the EGR system of the present embodiment, the passage of the housing outer wall portion 6 is exposed to the heat absorption portion exposed on the passage wall surface (second EGR gas passage wall surface) of the housing outer wall portion 6 of the housing 3. Since the plurality of cooling fins 9 are formed so as to protrude from the wall surface into the second EGR gas passage 12, they are formed inside the housing outer wall portion 6 when the EGR gas passes through the second EGR gas passage 12. The EGR gas can be efficiently cooled by the engine cooling water flowing through the cooling water passage 7.

  Accordingly, when the switching position of the four-way switching valve 4 of the EGR gas switching valve is set to the bypass fully closed position, that is, in the cool mode, the hot EGR gas flows from the first EGR gas passage 11 to the first opening of the housing 3. Even when leaking to the second EGR gas passage side through a square annular gap (clearance) formed between the opening peripheral edge of the portion 35 and the periphery of the four-way switching valve 4, the second EGR gas passage 12 The heat of the EGR gas that has flowed in, particularly the heat of the hot EGR gas that has leaked from the first EGR gas passage 11 to the second gas EGR passage side in the cool mode, is absorbed by, for example, engine cooling water that has an extremely low temperature compared to the EGR gas. be able to. As a result, the temperature of the EGR gas flowing into the second EGR gas passage 12, that is, the EGR gas (EGR cooler) whose temperature has risen due to leakage of hot EGR gas from the first EGR gas passage 11 to the second EGR gas passage in the cooled mode. The temperature of the EGR gas in which the cooled EGR gas and the hot EGR gas that have flowed into the second EGR gas passage 12 from the one outlet side tank chamber 24 are mixed and the temperature has increased can be lowered.

Therefore, while suppressing deterioration in mountability to vehicles such as automobiles and cost increase, the refrigerant recirculates to the intake passage of the engine due to leakage of hot EGR gas from the first EGR gas passage 11 to the second EGR gas passage side in the cooled mode. Since the temperature rise of the cooled EGR gas can be suppressed, it is possible to suppress a decrease in emission performance. In addition, since it is possible to compensate for a decrease in cooling efficiency of the EGR cooler module due to hot EGR gas leakage in the valve unit 2, an EGR gas cooling device that combines the EGR cooler 1 and the valve unit 2 (cooled mode and hot mode). The cooling performance of the EGR cooler module with a switching function can be improved.
Further, since the cooling efficiency in the EGR cooler module can be increased, the emission performance can be improved at a low cost.

[Modification]
In this embodiment, the actuator (second actuator) that drives the four-way switching valve 4 that is the valve body of the EGR gas switching valve is configured by a negative pressure actuated actuator including a negative pressure control valve and an electric vacuum pump. However, the actuator for driving the four-way switching valve 4 of the EGR gas switching valve is constituted by an electric actuator including an electric motor and a power transmission mechanism (for example, a gear reduction mechanism) or an electromagnetic actuator. Also good. Further, a valve urging means such as a spring for urging the four-way switching valve 4 of the EGR gas switching valve of the valve unit 2 in the valve closing direction (the side where the bypass passage 13 is closed) is provided inside the housing 3 of the valve unit 2. May be installed.
Further, the EGRV may not be mounted on the EGR cooler module. In the present embodiment, the EGRV is installed downstream of the EGR cooler 1 in the EGR gas flow direction, but the EGRV may be installed upstream of the EGR cooler 1 in the EGR gas flow direction.

  In this embodiment, the present invention is applied to an EGR cooler module including a U-turn flow type EGR cooler (exhaust gas cooler) 1 in which EGR gas (exhaust gas) flows in a U shape inside. You may apply to the EGR cooler module provided with the exhaust-gas cooler of the type into which an EGR gas (exhaust gas) flows into S shape or I shape inside. In this case, the outlet tank portion of the exhaust gas cooler and the cooler outlet port 34 of the housing 3 are connected by an exhaust gas pipe having no heat exchange function.

In this embodiment, the heat absorbing portion of the housing 3 is provided so as to be exposed at the passage wall surface of the housing outer wall portion 6 (A portion near the four-way switching valve on the right side of the second EGR gas passage 12 in the drawing: see FIG. 2). The heat absorbing portion of the housing 3 may be provided so as to be exposed at the passage wall surface of the housing outer wall portion 6 (B portion on the left side of the second EGR gas passage 12 in the drawing: see FIG. 2). Moreover, since the passage wall surface (heat absorption part) of the housing outer wall 6 is cooled by the cooling water flowing through the cooling water passage 7, the cooling fins 9 need not be provided. Alternatively, a cooling water passage may be formed inside the cooling fin 9.
In the present embodiment, the engine cooling water introduced into the EGR cooler 1 (cooling water for cooling the internal combustion engine and flowing into the exhaust gas cooler) is configured to flow through the cooling water passage 7. You may comprise so that cooling water with a temperature lower than engine cooling water may distribute | circulate the cooling water channel | path 7 without using engine cooling water.

In the present embodiment, the heat of the EGR gas flowing through the second EGR gas passage 12 of the housing 3 can be absorbed by the cooling water (for example, engine cooling water) flowing through the cooling water passage 7. A plurality of cooling fins 9 are provided so as to protrude from the passage wall surface of the second EGR gas passage 12 and into the second EGR gas passage 12 while being exposed on the second EGR gas passage wall surface. The housing is configured so that the heat of the exhaust gas flowing through the passage can be radiated (heat absorbed) to the air flowing along the outer surface of the housing outer wall portion (the housing wall portion separating the second gas passage and the outside of the housing) of the housing. You may provide the thermal radiation part (heat absorption part) exposed on the outer surface of an outer wall part.
Further, a heat radiating (cooling) fin may be formed on the heat radiating portion (heat absorbing portion) of the housing outer wall portion so as to protrude from the outer surface of the housing outer wall portion toward the opposite side with respect to the second gas passage side. . In this case, the contact area with the air (outside air) flowing along the outer surface of the outer wall of the housing, that is, the heat radiation area (heat absorption area) of the heat radiation section (heat absorption section) increases, so that the exhaust gas passes through the second gas passage. Air can be efficiently cooled by the air (outside air) flowing along the outer surface of the outer wall of the housing when passing.

It is explanatory drawing which showed the flow of EGR gas at the time of a cool mode (Example 1). (Example 1) which is the side view which showed the valve unit. It is explanatory drawing which showed the flow of EGR gas at the time of a hot mode (Example 1). It is the fragmentary sectional view which showed the EGR cooler module (prior art).

Explanation of symbols

1 EGR cooler (exhaust gas cooler)
2 Valve unit (exhaust gas switching valve)
3 Housing 4 4-way switching valve 5 Valve shaft (second rotary shaft)
6 Housing outer wall (housing wall)
7 Cooling water passage 9 Cooling fin (heat absorption part of housing)
11 First EGR gas passage (first gas passage)
12 Second EGR gas passage (second gas passage)
13 Bypass passage 23 EGR cooler inlet side tank chamber (exhaust gas cooler inlet)
24 EGR cooler outlet side tank chamber (exhaust gas cooler outlet)
31 EGR gas introduction port (first exhaust gas port)
32 EGR gas outlet port (second exhaust gas port)
33 Cooler inlet port (third exhaust gas port)
34 Cooler outlet port (4th exhaust gas port)
35 First Opening of Housing 36 Second Opening of Housing 37 Block

Claims (12)

(A) a housing having four exhaust gas ports respectively connected to an exhaust passage and an intake passage of an internal combustion engine and an inlet and an outlet of an exhaust gas cooler;
(B) a valve that is rotatably accommodated in the housing, and switches a communication state between the exhaust gas ports in the four exhaust gas ports.
A cooler mode for introducing and cooling the exhaust gas of the internal combustion engine into the exhaust gas cooler and a bypass mode for bypassing the exhaust gas of the internal combustion engine from the exhaust gas cooler according to a rotation angle of the valve inside the housing. In the exhaust gas switching valve to switch,
The four exhaust gas ports are
A gas introduction port communicating with the exhaust passage of the internal combustion engine;
A gas outlet port communicating with the intake passage of the internal combustion engine;
A cooler inlet port communicating with the exhaust gas cooler inlet;
And a cooler outlet port communicating with the outlet of the exhaust gas cooler,
The housing is
A first gas passage communicating the gas introduction port and the cooler inlet port;
A second gas passage communicating the cooler outlet port and the gas outlet port;
And having a heat absorbing portion exposed at the wall surface of the second gas passage so that the heat of the exhaust gas flowing into the second gas passage can be absorbed by the cooling fluid ,
The exhaust gas switching valve is characterized in that the heat absorption part is installed closer to the cooler outlet port than the valve in the bypass mode . The exhaust gas switching valve according to claim 1,
In the cooler mode, the exhaust gas switching valve is characterized in that the first gas passage and the second gas passage are formed inside the housing. The exhaust gas switching valve according to claim 1 or 2,
The valve is in the cooler mode,
An exhaust gas switching valve having a function as a partition plate for partitioning the interior of the housing into the first gas passage and the second gas passage. The exhaust gas switching valve according to any one of claims 1 to 3,
The exhaust gas switching valve, wherein the housing has a bypass passage that communicates the gas introduction port and the gas outlet port. The exhaust gas switching valve according to claim 4,
In the bypass mode, at least the bypass passage is formed inside the housing. The exhaust gas switching valve according to claim 4 or 5,
The valve is in the bypass mode,
An exhaust gas switching valve having a function as a partition plate for partitioning the interior of the housing into the bypass passage, the cooler inlet port, and the cooler outlet port. The exhaust gas switching valve according to any one of claims 1 to 6,
The exhaust gas switching valve, wherein the heat absorption part has a cooling fin so as to protrude from the wall surface of the second gas passage toward the second gas passage . The exhaust gas switching valve according to any one of claims 1 to 7,
The cooling fluid is cooling water for cooling the internal combustion engine,
An exhaust gas switching valve , wherein a cooling water passage through which the cooling water flows is formed inside the housing . The exhaust gas switching valve according to any one of claims 1 to 7 ,
The cooling fluid is cooling water flowing into the exhaust gas cooler ,
An exhaust gas switching valve, wherein a cooling water passage through which the cooling water flows is formed inside the housing. The exhaust gas switching valve according to claim 8 or 9 ,
The housing has a housing wall that partitions the second gas passage from the outside of the housing,
The exhaust gas switching valve , wherein the cooling water passage is formed inside the housing wall . In the exhaust gas switching valve according to any one of claims 1 to claim 10,
The housing has a housing wall that partitions the second gas passage from the outside of the housing,
The exhaust gas switching valve , wherein the heat absorption part is exposed at a second gas passage wall surface of the housing wall part. The exhaust gas switching valve according to claim 11 ,
The exhaust gas switching valve , wherein the heat absorption part has a cooling fin so as to protrude from the wall surface of the second gas passage of the housing wall part into the second gas passage .

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