JP2007192090A - Exhaust recirculation device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust recirculation device for an internal combustion engine, capable of restricting leak of condensation water generated in the exhaust recirculation device to the external. <P>SOLUTION: The exhaust recirculation device is provided with valve elements 38 disposed respectively on a first passage 37a to compose a part of an exhaust recirculation passage and a second passage 37b to compose part of a bypass passage to open/close the passages, and a valve stem 39 on which the valve elements 38 are integrally rotatably installed, extends so as to cross each of the first passage 37a and the second passage 37b, and whose one end is exposed out of a housing 37. The valve stem 39 is disposed so as to be deflected vertically above a center lines of the first passage 37a and the second passage 37b. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust gas recirculation device for an internal combustion engine that introduces part of the exhaust gas of the internal combustion engine into an intake system.

  A heat exchanger using cooling water as a refrigerant is provided in the exhaust gas recirculation passage, and a bypass passage that bypasses the heat exchanger is provided, and a gas taken out from the exhaust system (EGR gas) is passed through the heat exchanger while the bypass passage is provided. 2. Description of the Related Art There is known an exhaust gas recirculation device for an internal combustion engine configured to switch between a closed position and a position where an exhaust gas recirculation passage is closed while a bypass passage is opened to bypass a heat exchanger. In order to realize such switching of the passage, a valve body that opens and closes the exhaust gas recirculation passage and the bypass passage is provided, and one end of the valve shaft to which the valve body is attached so as to be integrally rotatable is exposed to the outside of the housing. There is a path switching device that rotationally drives the valve shaft between a position that opens the reflux path while closing the bypass path and a position that closes the exhaust path and opens the bypass path.

  By the way, in the case of an exhaust gas recirculation device equipped with a heat exchanger, the moisture in the exhaust gas is changed to condensed water by being cooled by the heat exchanger, and the condensed water is generated in the exhaust gas recirculation passage. There is a possibility of leaking out of the housing through the shaft. As a technique for reducing the condensed water generated in the exhaust gas recirculation apparatus, there is a technique for supplying high-temperature EGR gas to a position where such condensed water flows down and evaporating the condensed water using the heat of the gas (Patent Literature). 1). In addition, there is Patent Document 2 as a prior art document related to the present invention.

JP-A-9-088728 JP-A-2005-240669

  However, since the EGR gas having a temperature sufficient to evaporate the condensed water cannot be obtained under a condition where the exhaust temperature of the internal combustion engine is low, the technique of Patent Document 1 is insufficient as a measure for preventing leakage of the condensed water to the outside of the housing. It is.

  Then, an object of this invention is to provide the exhaust gas recirculation apparatus of the internal combustion engine which can suppress that the condensed water produced | generated with the exhaust gas recirculation apparatus leaks outside.

  The exhaust gas recirculation apparatus of the present invention includes an exhaust gas recirculation passage for introducing a part of exhaust gas of an internal combustion engine into an intake system, a cooling means provided in the exhaust gas recirculation passage, a bypass passage that bypasses the cooling means, and the exhaust gas Passage switching means switchable between a passage position that opens the reflux passage while closing the bypass passage and a bypass position that closes the exhaust passage and opens the bypass passage. The switching means includes a first passage that forms part of the exhaust gas recirculation passage and extends in a direction that intersects the vertical direction, and a second passage that forms part of the bypass passage and extends in a direction that intersects the vertical direction. Housing, a valve body that is provided in each of the first passage and the second passage and opens and closes each passage, and the valve body is attached so as to be integrally rotatable, and the first passage and the second passage. A valve shaft extending across each of the two and having one end exposed to the outside of the housing, and the valve shaft is disposed so as to deviate vertically above the center line of the first passage and the second passage. Thus, the above-described problem is solved (claim 1).

  According to this exhaust gas recirculation device, since the valve shaft is arranged so as to be vertically deviated from the center line of the first passage and the second passage, the valve shaft is formed from the condensed water accumulated at the bottom of the passage located vertically below. Can be released sufficiently. Therefore, it is possible to suppress the condensed water from leaking out of the housing through the valve shaft.

  It is sufficient if the valve shaft is disposed at a position that is vertically deviated from the center line of the passage. However, the valve shaft is disposed at an upper end portion that is located vertically above the first passage and the second passage. (Claim 2). By disposing the valve shaft in this way, the valve shaft can be further separated from the condensed water accumulated at the bottom of the passage, so that the effect of suppressing the leakage of condensed water to the outside of the housing is further improved.

  In the exhaust gas recirculation apparatus of the present invention, the switching means is connected to a cylindrical main body having a partition wall that divides the exhaust gas recirculation passage into a passage in which the cooling means is disposed and the bypass passage. A cooling unit may be provided, and the cooling unit may be arranged so as to be inclined so that the opposite side is located vertically below the side to which the switching means is connected (Claim 3). In this case, since the generated condensed water flows to the side away from the passage switching means by gravity, it is suppressed that condensed water accumulates in the vicinity of the passage switching means. Therefore, the risk of leakage of condensed water to the outside of the housing can be reduced.

  As described above, according to the exhaust gas recirculation apparatus of the present invention, the valve shafts that drive the valve bodies arranged in the first passage and the second passage are biased vertically upward from the center lines of these passages. Therefore, it is possible to suppress the condensed water generated by the exhaust gas recirculation device from leaking to the outside.

  FIG. 1 is a perspective view showing an external configuration of an exhaust gas recirculation apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view showing the main part of the internal configuration of the exhaust gas recirculation apparatus shown in FIG. FIG. As shown in FIG. 1, the exhaust gas recirculation device 1 has an exhaust gas recirculation passage 2 for extracting a part of the exhaust gas (EGR gas) of the internal combustion engine, and the exhaust gas recirculation passage 2 is used for cooling the EGR gas. The cooling unit 3 and an exhaust gas recirculation control valve 4 arranged on the downstream side of the cooling unit 3 to adjust the flow rate of the EGR gas are provided. The exhaust gas recirculation passage 2 has one upstream end connected to an exhaust system 100 of an internal combustion engine such as an exhaust manifold, and the other downstream end connected to an intake system 101 of the internal combustion engine such as an intake manifold.

  As shown in FIG. 2, the cooling unit 3 is connected to a cylindrical main body portion 31 provided with a partition wall 33 extending so as to divide the exhaust gas recirculation passage 2 into two passages, and to the downstream side of the main body portion 31. And a passage switching unit 32. The cooling unit 3 is disposed so as to be inclined such that the side (inlet side) opposite to the side (exit side) to which the passage switching unit 32 is connected is positioned vertically downward (see FIG. 1). A heat exchanger 36 serving as a cooling means is disposed in one passage 34 divided by the partition wall 33. The other passage 35 divided by the partition wall 33 functions as a bypass passage that bypasses the heat exchanger 36. The partition wall 33 extends to the boundary between the main body portion 31 and the passage switching portion 32. As shown in FIGS. 1 and 2, the heat exchanger 36 included in the main body 31 discharges a refrigerant such as cooling water introduced from the inlet 36 a from the outlet 36 b and circulates the refrigerant, thereby causing the heat exchanger 36. It is configured so that heat exchange can be performed between the EGR gas introduced into the refrigerant and the refrigerant.

  FIG. 3 is a schematic diagram schematically showing the passage switching unit 32 from the direction along the line III-III in FIG. 1. As shown in FIGS. 2 and 3, the passage switching unit 32 is connected to the passage 34 of the main body 31 and the first passage 37 a that is connected to the passage 34 of the main body 31 and forms part of the exhaust gas recirculation passage 2. And a housing 37 having a second passage 37b constituting a part of the bypass passage. The passages 37a and 37b are formed so as to extend in a direction intersecting the vertical direction. Each of the passages 37a and 37b is provided with a plate-like valve body 38 configured to correspond to the shape of the passage. Each valve body 38 is attached to the valve shaft 39 by a fastening means 7 such as a bolt, and the valve shaft 39 extends across the first passage 37a and the second passage 37b and is provided on the first passage 37a side. One end is exposed to the outside of the housing 37. The housing 37 is provided with a support portion 37c that rotatably supports the valve shaft 39, and the support portion 37c is configured by combining a plurality of washers having different diameters with each other (see FIG. 3) is provided. Gas leakage from between the valve shaft 39 and the housing 37 is suppressed by the gas seal 10. Further, as shown in FIG. 3, each passage 37a, 37b is provided with a valve seat 37d for seating the valve body 38 thereon. The valve shaft 39 is disposed so as to be vertically deviated from the center line CL1 of each of the first passage 37a and the second passage 37b (see also FIGS. 4 and 5). The center line CL1 means a straight line passing through the centroid of the cross section of the passage. In the form of illustration, it arrange | positions at the upper end part located in the vertically upper direction of each channel | path 37a, 37b. As described above, the passage switching unit 32 is configured such that each valve body 38 can rotate integrally with the valve shaft 39 around the rotation axis CL <b> 2 of the valve shaft 39.

  4 is a schematic cross-sectional view taken along line IV-IV in FIG. 3, and FIG. 5 is a schematic cross-sectional view taken along line V-V in FIG. As shown in these drawings, each valve body 38 is configured such that the valve body 38 of the first passage 37a and the valve body 38 of the second passage 37b are shifted from each other by approximately 90 ° with respect to the valve shaft 39. Is attached to the valve shaft 39. Therefore, as shown by the solid lines in FIGS. 4 and 5, when the first passage 37 a is opened by the valve body 38, the second passage 37 b is closed by the valve body 38. Conversely, as indicated by the phantom lines in FIGS. 4 and 5, when the first passage 37 a is closed by the valve body 38, the second passage 37 b is opened by the valve body 38. That is, the passage switching unit 32 changes the rotational position of the valve shaft 39 to open the exhaust gas recirculation passage (first passage 37a) while closing the bypass passage (second passage 37b), and the exhaust gas recirculation. It functions as a path switching means that can switch between a bypass position that closes the path and opens the bypass path. The valve shaft 39 is rotationally driven by an actuator 40 (see FIGS. 1 and 2) linked to one end thereof. 2 and 3 and FIGS. 4 and 5 indicate the passing positions, and the imaginary lines in FIGS. 4 and 5 indicate the bypass positions.

  According to the exhaust gas recirculation apparatus 1 described above, in the illustrated form, the valve shaft 39 is provided at the upper end of each of the passages 37a and 37b so that the valve shaft 39 is biased vertically upward from the center line CL1 of the first passage 37a and the second passage 37b. Since the shaft 39 is disposed, the valve shaft 39 can be sufficiently separated from the condensed water accumulated at the bottom of the passage located vertically below. Therefore, the generated condensed water can be prevented from leaking out of the housing 37 through the valve shaft 39. Further, since the cooling unit 3 is disposed so that the opposite side (inlet side) to the side (outlet side) to which the passage switching unit 32 is connected is positioned vertically downward, the cooling unit 3 is condensed outside the housing 37. The risk of water leakage can be reduced.

  This invention is not limited to the above form, You may implement with a various form. In the illustrated form, the cooling means and the bypass passage are integrated, but the present invention may be implemented as a form in which these are separated. Moreover, although the passage switching unit of the cooling unit is connected to the outlet side, the present invention may be implemented in a form connected to the inlet side.

The perspective view which showed the external appearance structure of the exhaust gas recirculation apparatus which concerns on embodiment of this invention. The cross-sectional schematic diagram which showed the principal part of the internal structure of the exhaust gas recirculation apparatus of FIG. 1 from the arrow A direction. The schematic diagram which showed typically the channel | path switching part from the direction in alignment with the III-III line of FIG. FIG. 4 is a schematic cross-sectional view taken along line IV-IV in FIG. 3. The cross-sectional schematic diagram along the VV line | wire of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exhaust gas recirculation apparatus 2 Exhaust gas recirculation passage 3 Cooling unit 101 Intake system 31 Main-body part 32 Passage switching part (passage switching means)
33 Bulkhead 36 Heat exchanger (cooling means)
35 passage (bypass passage)
37 Housing 37a First passage 37b Second passage 38 Valve body 39 Valve shaft CL1 Center line

Claims (3)

An exhaust gas recirculation passage for introducing a part of the exhaust gas of the internal combustion engine into the intake system, a cooling means provided in the exhaust gas recirculation passage, a bypass passage that bypasses the cooling means, and the exhaust gas recirculation passage are opened while Passage switching means switchable between a passing position for closing the bypass passage and a bypass position for closing the exhaust gas recirculation passage while opening the bypass passage;
The passage switching means includes a first passage that constitutes a part of the exhaust gas recirculation passage and extends in a direction intersecting the vertical direction, and a second passage that constitutes a part of the bypass passage and extends in a direction intersecting the vertical direction. A formed housing; a valve body provided in each of the first passage and the second passage; for opening and closing each passage; the valve body is attached to be integrally rotatable; and the first passage and the second passage A valve shaft that extends across each of the first and second ends and is exposed to the outside of the housing.
The exhaust gas recirculation apparatus for an internal combustion engine, wherein the valve shaft is disposed so as to be deviated vertically upward from a center line of the first passage and the second passage.   2. The exhaust gas recirculation apparatus for an internal combustion engine according to claim 1, wherein the valve shaft is disposed at an upper end portion located vertically above the first passage and the second passage.   A cooling unit in which the switching means is connected to a cylindrical main body having a partition wall that divides the exhaust gas recirculation passage into a passage in which the cooling means is disposed and the bypass passage; and the cooling unit includes the switching means The exhaust gas recirculation device for an internal combustion engine according to claim 1 or 2, wherein the exhaust gas recirculation device is arranged so as to be inclined so that the opposite side is located vertically below the side to which the is connected.

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