JP2008267320A - Connection structure for blow-by gas recirculation passage - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connection structure for a recirculation passage capable of inhibiting freezing of a recirculation passage outlet. <P>SOLUTION: The recirculation passage 2 re-circulates blow-by gas to an intake passage 1 of an internal combustion engine. A connection structure of the recirculation passage 2 and an intake air passage 1 is provided with a retraction part 3 formed to avoid flow of intake air indicated by an arrow A in the intake air passage 1, and a connection part 4 connected to a part of the retraction part 3 in the recirculation passage 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an improvement in a connection structure between a recirculation passage for recirculating blowby gas to an intake passage of an internal combustion engine and an intake passage.

  As a device applied to an in-vehicle internal combustion engine, a blow-by gas that ventilates combustion gas (blow-by gas) leaking into the crankcase from the gap between the cylinder and the piston and recirculates the ventilated blow-by gas into the intake air for processing. Gas processing devices are known. In such an internal combustion engine with a blow-by gas processing device, the blow-by gas recirculated into the intake air is recombusted in the combustion chamber, so that the amount of hydrocarbon (HC) discharged into the atmosphere can be reduced. Moreover, the deterioration of the oil by blow-by gas can be suppressed by ventilation inside the engine.

  Here, conventionally, as shown in FIG. 6, the recirculation passage 12 that recirculates the blow-by gas is connected to an introduction portion 13 formed in the intake passage 11. Water vapor in the reflux gas may freeze at the passage outlet (introduction section 13). If freezing progresses, an exit will be obstruct | occluded and the situation which interferes with the recirculation | reflux of blow-by gas will generate | occur | produce.

Thus, conventionally, an improved connection structure has been proposed, such as the device described in Patent Document 1 or Patent Document 2, so as to prevent the reflux passage outlet from being blocked.
In the connection structure described in Patent Document 1, the connection end portion of the recirculation passage extending into the intake passage is molded into a shape that expands into a substantially trumpet shape. In this case, when water is frozen at the reflux passage outlet, the connection end is expanded in a substantially trumpet shape and the diameter of the reflux passage outlet is large, so that the blockage due to freezing is delayed.

Further, in the connection structure described in Patent Document 2, the return passage is inserted to the center of the intake passage, and the insertion angle of the return passage is set within a certain angle range. This is because even if water vapor becomes a water droplet in the reflux passage, it flows down to the tip of the reflux passage through the inner wall of the reflux passage, and the water droplets are blown off by the momentum of the intake air flowing through the inside of the intake passage, thereby freezing at the reflux passage outlet. It is an avoidance.
Japanese Utility Model Publication No. 5-30411 Japanese Utility Model Publication No. 6-30409

By the way, although the connection structure of patent document 1 can delay the obstruction | occlusion by freezing, the freezing of the water | moisture content in a reflux passage exit is inevitable.
Further, in the connection structure of Patent Document 2, since the return passage is inserted into the intake passage, the insertion portion of the return passage is cooled by the intake air. For this reason, there is a possibility that the water droplet is cooled and frozen before reaching the opening.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a connection structure for a return passage that can suppress freezing of the return passage outlet.

In the following, means for achieving the above object and its effects are described.
According to a first aspect of the present invention, in the connection structure between the recirculation passage for recirculating blow-by gas to the intake passage of the internal combustion engine and the intake passage, a retracting portion formed to avoid the flow of intake air in the intake passage; And a connecting portion connected to a part of the retracting portion in the reflux passage.

  According to the above configuration, since the retracting portion formed so as to avoid the flow of the intake air is provided in the intake passage, cooling by the intake air is suppressed in the retracting portion. And since the connection part connected to a part of evacuation part in the recirculation | reflux path | pass, blow-by gas is discharged | emitted from the connection part with the evacuation part by which cooling was suppressed. As a result, freezing of the reflux passage outlet can be suppressed.

  Specifically, as described in claim 2, in the connection structure of the reflux passage according to claim 1, the flow passage cross-sectional area of the blow-by gas in the retraction portion is the connection portion in the connection portion of the return passage. It is possible to adopt a mode in which the flow passage is set to be larger than the cross-sectional area of the blowby gas.

  According to a third aspect of the present invention, in the connection structure of the return passage according to the first or second aspect, in the connection portion, the return passage has an extended line on the center side of the intake passage from the inner wall of the retracting portion. It is connected so that it becomes.

  According to the above configuration, the return passage in the connection portion is connected such that the extension line is closer to the center side of the intake passage than the inner wall of the retracting portion, so that the blow-by gas discharged from the connection portion of the return passage is It hits against the inner wall of a evacuation part. As a result, it is possible to suppress the moisture in the blow-by gas from adhering to the retracting portion and freezing.

  According to a fourth aspect of the present invention, in the connection structure of the return passage according to any one of the first to third aspects, the return passage is connected to the connection portion so that the blow-by gas is directed downstream of the intake air. It is characterized by being.

  According to the above configuration, since the return passage is connected in the connecting portion so that the blow-by gas is directed to the downstream side of the intake air, the blow-by gas diffuses quickly along the flow of the intake air. For this reason, it can suppress that the water | moisture content in blow-by gas retains in a recirculation passage exit, and can further suppress freezing of a recirculation passage exit.

  According to a fifth aspect of the present invention, in the connection structure for the return passage according to any one of the first to fourth aspects, the connection portion is provided at a position separated from a boundary between the main body of the intake passage and the retracting portion. It is characterized by being.

  In the retracting portion, the closer to the boundary with the main body of the intake passage, the easier it is cooled by the intake air. The main body of the intake passage refers to a portion where the retracting portion is not formed in the intake passage, that is, a portion forming the main flow of intake air.

  In this regard, according to the above configuration, the connection portion is provided at a position separated from the boundary between the main body of the intake passage and the retracting portion, so that cooling due to intake air at the connection portion can be suppressed. Thereby, the freezing of the water | moisture content in a connection part, ie, the exit of a recirculation | reflux path | pass, can further be suppressed.

  According to a sixth aspect of the present invention, in the connection structure of the return passage according to any one of the first to fifth aspects, the connection portion extends in a direction approaching the center of the main body of the intake passage in the retracting portion. It has the extended part.

  According to the above configuration, since the connecting portion has the extending portion extending in the direction approaching the center of the main body of the intake passage in the retracting portion, even if moisture adheres to the reflux passage outlet, the connecting portion hangs down from the extending portion. Can be made. As a result, it is possible to suppress moisture from being transmitted from the connecting portion to the inner wall of the retracting portion, and thus it is possible to suppress moisture from being frozen in the retracting portion.

  Hereinafter, the connection structure of the blowby gas recirculation passage according to the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view in a plane passing through the center of the connection portion of the return passage in parallel with the flow direction of the intake air in the intake passage. 2 is a cross-sectional view taken along line XX of FIG.

  The blow-by gas is introduced into the intake passage 1 of the internal combustion engine from the recirculation passage 2 that recirculates the blow-by gas. The reflux passage 2 includes a hose portion 6 having one end connected to the crankcase of the internal combustion engine, and a connection portion 4 for connecting the other end of the hose portion 6 to the intake passage 1.

  A retracting portion 3 is formed in the intake passage 1 so as to avoid the flow of intake air indicated by an arrow A. The retracting portion 3 is formed in a substantially hemispherical shape on a part of the outer periphery of the intake passage main body 1A, and protrudes from the outer periphery of the intake passage main body 1A. The intake passage main body 1A is a portion where the retracting portion 3 is not formed in the intake passage 1, that is, a portion forming a main flow of intake air. The retracting portion 3 is disposed vertically above the intake passage main body 1A. The evacuation unit 3 is formed in a minimum size that can avoid the flow of intake air indicated by the arrow A based on experiments and the like.

A connecting portion 4 of the reflux passage 2 is connected to a part of the retracting portion 3. The retracting portion 3, the connecting portion 4, and the intake passage main body 1A are integrally molded from resin or the like.
The connecting portion 4 is molded into a cylindrical shape having an outer diameter that can fit and fix the tip of the hose portion 6 without a gap. Here, the flow passage cross-sectional area of the blow-by gas in the retracting portion 3 is set larger than the flow passage cross-sectional area of the blow-by gas in the connection portion 4 of the reflux passage 2. The connecting portion 4 is provided at a position away from the boundary between the intake passage main body 1A and the retracting portion 3 so that the blow-by gas flowing through the recirculation passage 2 is directed downstream of the intake air flow indicated by the arrow A. Further, the reflux passage 2 is connected at the connection portion 4 so that the extension line is closer to the center of the intake passage 1 than the inner wall of the retracting portion 3.

  Further, the connecting portion 4 has an extending portion 5 that extends in a direction approaching the center of the intake passage main body 1 </ b> A in the retracting portion 3. The extending portion 5 is a cylindrical shape having the same diameter as that of the connecting portion 4 and is provided short so as not to be directly exposed to the intake air flow indicated by the arrow A.

According to the connection structure of the reflux passage described above, the following effects can be obtained.
(1) Since the intake passage 1 includes the retracting portion 3 formed so as to avoid the flow of intake air, the retracting portion 3 suppresses cooling due to the intake air flow indicated by the arrow A. And since the connection part 4 connected to a part of retraction | saving part 3 in the recirculation | reflux passage 2 is provided, blow-by gas is discharged | emitted from the connection part 4 with the retraction | saving part 3 by which cooling was suppressed. As a result, freezing of the outlet of the reflux passage 2 can be suppressed.

  (2) Since the reflux passage 2 is connected so that the blow-by gas is directed toward the downstream side of the intake air at the connection portion 4, the blow-by gas diffuses quickly along the flow of the intake air indicated by the arrow A. For this reason, it can suppress that the water | moisture content in blow-by gas stays in the exit of the recirculation | reflux channel | path 2, and can further suppress freezing of the exit of the recirculation | reflux channel | path 2.

  (3) The position closer to the boundary with the intake passage body 1A in the retracting portion 3 is more easily cooled by intake air. In this respect, since the connection portion 4 is provided at a position separated from the boundary between the intake passage main body 1A and the retracting portion 3, cooling due to intake air at the connection portion 4 can be suppressed. Thereby, the freezing of the water | moisture content in the connection part 4, ie, the exit of the recirculation | reflux path | pass 2, can further be suppressed.

  (4) Since the connecting portion 4 has the extending portion 5 extending in the direction approaching the center of the intake passage main body 1A in the retracting portion 3, even if moisture adheres to the outlet of the reflux passage 2, the extending portion It can be dropped from 5. As a result, it is possible to suppress moisture from being transmitted from the connecting portion 4 to the inner wall of the retracting portion 3, so that moisture freezing in the retracting portion 3 can be suppressed.

  The connection structure of the reflux passage according to the present invention is not limited to the configuration exemplified in the above embodiment, and can be implemented as, for example, the following form obtained by appropriately modifying the embodiment. .

  In the above embodiment, the example in which the retracting portion 3 is substantially hemispherical is shown. However, the retracting portion 3 may be formed so as to avoid the flow of intake air, and may have a shape different from the substantially hemispherical shape. As an example, a connection structure of the reflux passage 22 in which the retracting portion 23 has a substantially rectangular parallelepiped shape as shown in FIG. 3 may be employed.

  -In the said embodiment, the example which has the extension part 5 was shown. However, the connection part 24 which does not have an extension part like FIG. 3 is also employable. Even in this case, the above effects (1) to (3) can be achieved.

  In the above embodiment, the example in which the connection portion 4 is provided at a position separated from the boundary between the intake passage main body 1A and the retracting portion 3 has been described. However, as shown in FIG. 4, a configuration in which the connecting portion 34 is provided at a position in contact with the boundary between the intake passage main body 31 </ b> A and the retracting portion 33 can also be employed. Even in this case, it is possible to achieve the effects equivalent to the above effects (1) and (2).

  As shown in FIG. 5, it is also possible to adopt a mode in which the retracting portion 43 is provided vertically below the intake passage main body 41A. That is, the disposition position of the retracting portion is not necessarily limited to the vertically upper side of the intake passage main body.

Sectional drawing which shows the connection structure of the reflux path concerning this invention. XX sectional drawing of FIG. Sectional drawing which shows the modification of the connection structure of the reflux path concerning this invention. Sectional drawing which shows the other modification of the connection structure of the reflux path concerning this invention. Sectional drawing which shows the other modification of the connection structure of the reflux path concerning this invention. Sectional drawing which shows the connection structure of the conventional recirculation | reflux channel | path.

Explanation of symbols

  1, 11, 21, 31, 41 ... intake passage, 2, 12, 22, 32, 42 ... return passage, 3, 13, 23, 33, 43 ... retraction part, 4, 24, 34, 44 ... connection part, 5 ... Extension part, 6, 26, 36, 46 ... Reflux passage hose.

Claims (6)

In the connection structure between the recirculation passage for recirculating blowby gas to the intake passage of the internal combustion engine and the intake passage,
A recirculation passage connection structure comprising: a retraction portion formed so as to avoid a flow of intake air in the intake passage; and a connection portion connected to a part of the retraction portion in the recirculation passage. The flow passage cross-sectional area of the blow-by gas in the retracting portion is set larger than the flow passage cross-sectional area of the blow-by gas in the connection portion of the recirculation passage. Connection structure. The return path of the return path according to claim 1 or 2, wherein the return path in the connection part is connected so that an extension line thereof is closer to a center side of the intake path than an inner wall of the retracting part. Connection structure. The connection structure of the return passage according to any one of claims 1 to 3, wherein the return passage is connected so that the blow-by gas is directed downstream of the intake air in the connection portion. The connection structure of the return passage according to any one of claims 1 to 4, wherein the connection portion is provided at a position separated from a boundary between the main body of the intake passage and the retracting portion. The connection structure of the return passage according to any one of claims 1 to 5, wherein the connection portion includes an extension portion extending in a direction approaching the center of the main body of the intake passage in the retracting portion. .

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