Patent Publication Number: US-2019186445-A1

Title: Blow-by gas processing device, and engine

Description:
INCORPORATION BY REFERENCE 
     The disclosure of Japanese Patent Application No. 2017-239935 filed on Dec. 14, 2017 including the specification, drawings and abstract is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The disclosure relates to a blow-by gas processing device including a blow-by gas pipe through which blow-by gas to be introduced into an intake pipe flows, and relates also an engine. 
     2. Description of Related Art 
     A blow-by gas processing device described in Japanese Patent No. 3051391 includes a blow-by gas pipe extending in a direction in which a crankshaft of an engine extends (hereinafter, referred to as “extending direction of the crankshaft”). An inlet portion through which the blow-by gas flows into the blow-by gas pipe is disposed at a base end portion of the blow-by gas pipe. In addition, a peripheral wall of the blow-by gas pipe is provided with a plurality of communication holes arranged in a direction in which the blow-by gas pipe extends (hereinafter, referred to as “extending direction of the blow-by gas pipe”). The blow-by gas pipe communicates with an intake pipe through the communication holes. Thus, the blow-by gas flowing through the blow-by gas pipe is introduced into the intake pipe through the communication holes. 
     SUMMARY 
     The communication holes arranged in the extending direction of the blow-by gas pipe include a farthest communication hole. The farthest communication hole is a communication hole located farthest from the inlet portion, among the communication holes described above. In the blow-by gas pipe described above, the farthest communication hole is located closer to the inlet portion than a distal end portion of the blow-by gas pipe is. Thus, in the distal end portion of the blow-by gas pipe, the blow-by gas accumulates without being introduced into the intake pipe. 
     When the blow-by gas pipe is applied to an engine that is mounted in a vehicle such that the extending direction of a crankshaft substantially coincides with the front-rear direction of the vehicle, the air flowing from a front side of the vehicle collides with the distal end portion of the blow-by gas pipe, in which the blow-by gas accumulates. When the temperature of the air that collides with the distal end portion as described above is considerably low, moisture contained in the blow-by gas that has accumulated in the distal end portion may freeze, leading to blockage of the farthest communication hole. As a result, the blow-by gas in the blow-by gas pipe may not be easily introduced into the intake pipe through the farthest communication hole. When the blow-by gas is hindered from being introduced into the intake pipe through at least one of the communication holes, the blow-by gas is not easily mixed homogeneously with intake air in the intake pipe. This may cause variations in the amounts of blow-by gas to be introduced into respective cylinders. 
     In view of this, the blow-by gas processing device described above still has room for improvement in terms of reduction of accumulation of the blow-by gas in the distal end portion of the blow-by gas pipe. The disclosure provides a blow-by gas processing device including a blow-by gas pipe configured to reduce accumulation of blow-by gas in a distal end portion of the blow-by gas pipe, and provides an engine. 
     A first aspect of the disclosure relates to a blow-by gas processing device for an engine including an intake pipe. The blow-by gas processing device includes a blow-by gas pipe through which blow-by gas flows. The blow-by gas flows into the blow-by gas pipe from a base end of the blow-by gas pipe. The blow-by gas pipe is disposed on a blow-by gas introduced portion that is a part of the intake pipe of the engine. A peripheral wall of the blow-by gas pipe is provided with a plurality of communication holes arranged in an extending direction of the blow-by gas pipe. The blow-by gas in the blow-by gas pipe is introduced into the blow-by gas introduced portion through the plurality of communication holes. A farthest communication hole is provided in a distal end portion of the blow-by gas pipe. The farthest communication hole is included in the plurality of communication holes. The farthest communication hole is located farthest from the base end of the blow-by gas pipe in the extending direction of the blow-by gas pipe, among the plurality of communication holes. A guide wall portion is provided in a part of the peripheral wall of the blow-by gas pipe. The part of the peripheral wall, in which the guide wall portion is provided, is located on the opposite side of a central axis of the blow-by gas pipe from a position of the farthest communication hole. The guide wall portion is configured to approach the blow-by gas introduced portion as the guide wall portion extends toward a distal end of the blow-by gas pipe in the extending direction of the blow-by gas pipe. 
     According to the first aspect, the blow-by gas that has flowed into the blow-by gas pipe from the base end flows toward the distal end of the blow-by gas pipe. The blow-by gas flows into the plurality of communication holes, and is then introduced into the blow-by gas introduced portion of the intake pipe through the plurality of communication holes. 
     In the first aspect, the farthest communication hole is provided in the peripheral wall of the blow-by gas pipe such that the farthest communication hole is located in the distal end portion of the blow-by gas pipe. In addition, the guide wall portion is provided in the part of the peripheral wall of the blow-by gas pipe. Thus, the blow-by gas flowing toward the distal end of the blow-by gas pipe is guided toward the farthest communication hole by the guide wall portion. The blow-by gas that has been guided toward the farthest communication hole by the guide wall portion is introduced into the blow-by gas introduced portion of the intake pipe through the farthest communication hole. As a result, it is possible to reduce the occurrence of a situation where the blow-by gas accumulates in the distal end portion of the blow-by gas pipe without flowing into the farthest communication hole. It is therefore possible to reduce accumulation of the blow-by gas in the distal end portion of the blow-by gas pipe. Thus, even when the distal end portion of the blow-by gas pipe is exposed to low-temperature air, the moisture contained in the blow-by gas is restrained from freezing in the distal end portion. As a result, blockage of the farthest communication hole is reduced. Thus, it is possible to reduce the occurrence of a situation where the blow-by gas is not easily introduced into the intake pipe through the farthest communication hole. 
     If the guide wall portion inclined as described above is provided so as to extend over a wide region, the internal volume of the blow-by gas pipe is small. In view of this, the guide wall portion may be located closer to the distal end of the blow-by gas pipe than a second-farthest communication hole is. The second-farthest communication hole is included in the plurality of communication holes, and the second-farthest communication hole is adjacent to the farthest communication hole in the extending direction of the blow-by gas pipe. With this configuration, the internal volume of the blow-by gas pipe is less likely to be smaller than that when the guide wall portion extends to a position that is closer to the base end than the second-farthest communication hole is. 
     A second aspect of the disclosure relates to an engine including: an intake pipe including a blow-by gas introduced portion; and a blow-by gas processing device including a blow-by gas pipe through which blow-by gas flows. The blow-by gas flows into the blow-by gas pipe from a base end of the blow-by gas pipe. The blow-by gas pipe is disposed on the blow-by gas introduced portion. A peripheral wall of the blow-by gas pipe is provided with a plurality of communication holes arranged in an extending direction of the blow-by gas pipe. The blow-by gas in the blow-by gas pipe is introduced into the blow-by gas introduced portion through the plurality of communication holes. A farthest communication hole is provided in a distal end portion of the blow-by gas pipe. The farthest communication hole is included in the plurality of communication holes. The farthest communication hole is located farthest from the base end of the blow-by gas pipe in the extending direction of the blow-by gas pipe among the plurality of communication holes. A guide wall portion is provided in a part of the peripheral wall of the blow-by gas pipe. The part of the peripheral wall, in which the guide wall portion is provided, is located on the opposite side of a central axis of the blow-by gas pipe from a position of the farthest communication hole. The guide wall portion is configured to approach the blow-by gas introduced portion as the guide wall portion extends toward a distal end of the blow-by gas pipe in the extending direction of the blow-by gas pipe. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein: 
         FIG. 1  is a front view schematically illustrating an engine to which a blow-by gas processing device according to an embodiment is applied; 
         FIG. 2  is a plan view schematically illustrating a blow-by gas pipe of the blow-by gas processing device and an intake pipe of the engine; 
         FIG. 3  is a sectional view taken along line in  FIG. 2 , and illustrating a sectional shape of the blow-by gas pipe and a part of a sectional shape of a surge tank included in the intake pipe; and 
         FIG. 4  is a sectional view illustrating the blow-by gas pipe included in the blow-by gas processing device and a part of the surge tank included in the intake pipe according to another embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, a blow-by gas processing device according to an embodiment will be described with reference to  FIG. 1  to  FIG. 3 .  FIG. 1  schematically illustrates an engine  10  to which a blow-by gas processing device  30  according to the present embodiment is applied. As illustrated in  FIG. 1 , the engine  10  is a V-engine including a first bank  11  and a second bank  12 . Each of the first bank  11  and the second bank  12  includes a plurality of cylinders arranged in a direction in which a crankshaft  13  extends (hereinafter, referred to as “extending direction of the crankshaft  13 ”). 
     As illustrated in  FIG. 1  and  FIG. 2 , an intake pipe  15  of the engine  10  includes a first intercooler  16  disposed above the first bank  11 , and a second intercooler  17  disposed above the second bank  12 . Intake air flows into the first intercooler  16  through a first pipe  18 . Similarly, intake air flows into the second intercooler  17  through a second pipe  19 . The intake pipe  15  further includes a surge tank  20  disposed between the first intercooler  16  and the second intercooler  17 , and an intake manifold  21  connected to the surge tank  20 . The intake air that has been cooled by the first intercooler  16  and the intake air that has been cooled by the second intercooler  17  flow into the surge tank  20 . Then, the intake air that has flowed from the surge tank  20  into the intake manifold  21  is introduced into each of the cylinders. 
     The blow-by gas processing device  30  includes a blow-by gas pipe  31  configured to introduce the blow-by gas into the intake pipe  15 . A predetermined direction X that is a direction in which the blow-by gas pipe  31  extends (hereinafter, referred to as “extending direction of the blow-by gas pipe  31 ”) as indicated by an arrowed line in  FIG. 2  substantially coincides with the extending direction of the crankshaft  13 . The blow-by gas pipe  31  is disposed on the surge tank  20 . That is, the surge tank  20  in the present embodiment is an example of “blow-by gas introduced portion” which is included in the intake pipe  15 , and into which the blow-by gas is introduced through the blow-by gas pipe  31 . 
     As illustrated in  FIG. 2 , an inlet portion  32  through which the blow-by gas flows into the blow-by gas pipe  31  is disposed at a base end portion  311  (an upper end portion in  FIG. 2 ) of the blow-by gas pipe  31  in the predetermined direction X. A tube  33  through which the blow-by gas flows is connected to the inlet portion  32 . 
     As illustrated in  FIG. 3 , a part (a lower part in  FIG. 3 ) of a peripheral wall  41  of the blow-by gas pipe  31 , which faces the surge tank  20 , is provided with a plurality of (three in an example illustrated in  FIG. 3 ) communication holes  42 A,  42 B,  42 C arranged in the predetermined direction X. That is, the part provided with the communication holes  42 A,  42 B,  42 C faces the surge tank  20 . Further, a part of the surge tank  20 , on which the blow-by gas pipe  31  is disposed, is provided with a plurality of through-holes  201  corresponding to the communication holes  42 A,  42 B,  42 C. The number of the through-holes  201  is equal to the number of the communication holes  42 A,  42 B,  42 C. Thus, the blow-by gas in the blow-by gas pipe  31  is introduced into the surge tank  20  through the communication holes  42 A,  42 B,  42 C and the through-holes  201  corresponding to the communication holes  42 A,  42 B,  42 C. 
     A first communication hole  42 A among the communication holes  42 A,  42 B,  42 C is provided in a distal end portion  312  (a left end portion in  FIG. 3 ) of the blow-by gas pipe  31  in the predetermined direction X. That is, among the communication holes  42 A,  42 B,  42 C, the first communication hole  42 A is located farthest from the inlet portion  32 . Further, among the communication holes  42 A,  42 B,  42 C, a third communication hole  42 C is located closest to the inlet portion  32 . In addition, among the communication holes  42 A,  42 B,  42 C, a second communication hole  42 B is located between the first communication hole  42 A and the third communication hole  42 C. That is, the second communication hole  42 B is adjacent to the first communication hole  42 A in the predetermined direction X. Therefore, the first communication hole  42 A in the present embodiment is an example of “farthest communication hole”, and the second communication hole  42 B in the present embodiment is an example of “second-farthest communication hole”. 
     A part of the peripheral wall  41  of the blow-by gas pipe  31  serves as a guide wall portion  43  configured to guide the blow-by gas to the first communication hole  42 A. The guide wall portion  43  is located on the opposite side of a central axis Z of the blow-by gas pipe  31  from a position of the first communication hole  42 A, and is located closer, in the predetermined direction X, to the distal end of the blow-by gas pipe  31  than the second communication hole  42 B is (i.e., is located on the left side of the second communication hole  42 B in  FIG. 3 ). The guide wall portion  43  is inclined with respect to the predetermined direction X such that the guide wall portion  43  approaches (i.e., the guide wall portion  43  is closer to) the surge tank  20  as the guide wall portion  43  extends toward the distal end of the blow-by gas pipe  31  in the predetermined direction X. That is, the guide wall portion  43  is inclined with respect to the predetermined direction X such that the distance between the guide wall portion  43  and the surge tank  20  decreases as the guide wall portion  43  extends toward the distal end of the blow-by gas pipe  31  in the predetermined direction X. 
     The operation and advantageous effect of the present embodiment will be described below. The blow-by gas that has flowed into the blow-by gas pipe  31  through the inlet portion  32  flows toward the distal end as indicated by arrowed lines in  FIG. 3 . The blow-by gas flows into the communication holes  42 A,  42 B,  42 C, and is then introduced into the surge tank  20  through the communication holes  42 A,  42 B,  42 C, and the through-holes  201 . 
     In the present embodiment, the first communication hole  42 A is provided in the peripheral wall  41  of the blow-by gas pipe  31  such that the first communication hole  42 A is located in the distal end portion  312  of the blow-by gas pipe  31 . In addition, the guide wall portion  43  is provided in the part of the peripheral wall  41  of the blow-by gas pipe  31  such that the guide wall portion  43  is located closer to the distal end of the blow-by gas pipe  31  than the second communication hole  42 B is. Thus, the blow-by gas flowing toward the distal end of the blow-by gas pipe  31  is guided toward the first communication hole  42 A by the guide wall portion  43 . The blow-by gas that has been guided toward the first communication hole  42 A by the guide wall portion  43  is introduced into the surge tank  20  through the first communication hole  42 A and the through-hole  201  that communicates with the first communication hole  42 A. As a result, it is possible to reduce the occurrence of a situation where the blow-by gas accumulates in the distal end portion  312  of the blow-by gas pipe  31  without flowing into the first communication hole  42 A. 
     When the engine  10  is disposed in an engine compartment, for example, such that the extending direction of the crankshaft  13  substantially coincides with the vehicle front-rear direction, the distal end portion  312  of the blow-by gas pipe  31  is a front end portion of the blow-by gas pipe  31  in the vehicle front-rear direction. In this case, the air flowing from a front side of the vehicle collides with the distal end portion  312 . When the temperature of the air that collides with the distal end portion  312  is considerably low, the moisture contained in the blow-by gas may freeze in the distal end portion  312 . In this regard, according to the present embodiment, it is possible to reduce accumulation of the blow-by gas in the distal end portion  312 . Thus, it is possible to restrain the moisture contained in the blow-by gas from freezing in the distal end portion  312 . 
     The moisture contained in the blow-by gas is restrained from freezing in the distal end portion  312  as described above, and thus blockage of the first communication hole  42 A is restrained. Thus, it is possible to reduce the occurrence of a situation where the blow-by gas is not easily introduced into the surge tank  20  through the first communication hole  42 A. That is, the blow-by gas can be appropriately introduced into the surge tank  20  through the first communication hole  42 A. Thus, even when the distal end portion  312  of the blow-by gas pipe  31  is exposed to low-temperature air, it is possible to reduce the occurrence of a situation where the blow-by gas is not easily mixed homogeneously with the intake air in the surge tank  20 . As a result, it is possible to reduce variations in the amounts of the blow-by gas to be introduced into the respective cylinders. 
     The foregoing embodiment may be modified as follows. The foregoing embodiment and modified examples described below may be combined with each other within a range where a technical contradiction does not arise. 
     For example, as illustrated in  FIG. 4 , the blow-by gas pipe  31  may be configured such that a guide wall portion  43 A extends to a position that is closer, in the predetermined direction X, to the base end portion  311  than the second communication hole  42 B is. As long as the peripheral wall  41  of the blow-by gas pipe  31  is provided with a plurality of communication holes, the number of the communication holes provided in the peripheral wall  41  may be two, or may be four or greater (for example, five). 
     An engine to which the blow-by gas processing device is applied may be an engine (for example, an inline engine) other than a V-engine. A part of the intake pipe, to which the blow-by gas pipe  31  is attached, may be a part of the intake pipe other than the surge tank  20 . The blow-by gas pipe  31  may be attached to, for example, the intake manifold  21 , so that the blow-by gas can be introduced into each branch pipe of the intake manifold  21  through a communication hole. The intake manifold  21  in this case is an example of “blow-by gas introduced portion”.