JP2005120977A - Breather structure for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a breather structure for an engine, allowing effective separation and removal of water from blow-by gas. <P>SOLUTION: The breather structure has a breather passage 8 for communicating a crank room 1a with the downstream side of a cleaner element 50 located inward from an air cleaner 3. An inlet portion 33 provided on a case 30 of the air cleaner 3 in the breather passage 8 and an intake output portion 34 of a case 31 are connected to each other via a passage curved portion 93. A drain hole 95 is formed in the passage curved portion 93 for draining water separated from the blow-by gas G passing through the breather passage 8 into the case 31. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a breather structure for a four-cycle engine used as a drive source for a work machine such as a small snowplow.

Conventionally, a breather passage of a four-cycle engine has been formed with a breather chamber that guides the blow-by gas leaked from the combustion chamber through the outer periphery of the piston into the crank chamber, and oil components such as oil mist mixed in the blow-by gas in the breather chamber The oil component is returned to the crank chamber, and the blow-by gas from which the oil component has been removed is sent from the intake system to the combustion chamber for recombustion (see Patent Document 1).
Utility Model Registration No. 2556039

  However, the blow-by gas leaking from the combustion chamber contains a large amount of moisture. For this reason, when the blow-by gas is sent to the intake system, it is preferable to remove the moisture contained in the blow-by gas. However, in the above-described conventional one, it is not sufficient to separate and remove the moisture from the blow-by gas.

  Therefore, an object of the present invention is to provide a breather structure for an engine that can effectively separate and remove moisture contained in blow-by gas.

  In order to achieve the above object, the breather structure for an engine according to the present invention has a breather passage that communicates the crank chamber with the downstream side of the cleaner element inside the air cleaner, and an inlet provided in the case of the air cleaner in the breather passage. And a suction passage portion of the case are connected by a curved passage curved portion, and a drain hole is formed in the passage curved portion for discharging moisture separated from blow-by gas passing through the breather passage into the case. .

  When blowby gas from the crank chamber passes through the breather passage, oil components such as oil mist are separated and removed. In addition, when blow-by gas passes through the curved passage portion formed in the breather passage, moisture having a large specific gravity collides with the inner surface of the curved passage portion by centrifugal force and is separated and removed. It is sent to the intake system together with the intake air purified by the cleaner element from the outlet. On the other hand, the moisture separated and removed from the blow-by gas is discharged into the case of the air cleaner from the drain hole formed in the passage curved portion.

  In a preferred embodiment of the present invention, a projecting portion with which blow-by gas collides is formed at the inlet portion. According to this configuration, the blow-by gas passing through the breather passage collides with the protrusions, thereby further promoting the separation of moisture contained in the blow-by gas.

  In a preferred embodiment of the present invention, the inlet portion is located below the intake outlet portion, and a passage for changing the flow direction of blow-by gas to a zigzag is formed in the passage curved portion, and the inlet portion The drain hole is formed in the lowermost part of. According to this configuration, the blow-by gas is sent upward through the zigzag passage from the inlet portion toward the intake outlet portion. The separation and removal of large moisture is performed better. Further, the water separated and removed from the blow-by gas is discharged into the case from a drain hole provided in the lowest part of the inlet portion.

  Further, in a preferred embodiment of the present invention, the inlet portion is located in the vicinity of the intake outlet portion, and the curved passage portion is formed by a U-shaped duct, and a connection portion between the duct and the inlet portion is formed. The drain hole is formed in the lower part. According to this configuration, moisture having a large specific gravity in the blowby gas is separated and removed by the centrifugal force when passing through the U-shaped duct provided in the breather passage. Moisture separated and removed from the blow-by gas is discharged into the case from a drain hole formed in a lower portion of the connecting portion between the duct and the inlet.

  As described above, according to the breather structure of the present invention, the moisture in the blow-by gas can be effectively separated and removed and discharged into the case of the air cleaner.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a partially cutaway plan view showing a main part of a general-purpose four-cycle two-cylinder engine to which a breather structure according to a first embodiment of the present invention is applied, and FIG. 2 is taken along line II-II in FIG. FIG. This engine is mounted on a work machine such as a small snowplow and serves as a drive source for the engine. Two cylinders 2 are integrally provided in a V shape in the crankcase 1 of FIG. The cylinder head 21 is attached to each cylinder 2, and the oil pan 10 is attached to the lower part of the crankcase 1. Further, an air cleaner 3 and a carburetor 4 constituting an intake system shown in FIG. 2 are disposed on the outer side of the crankcase 1. A crankshaft 5 as an output shaft is supported by the crankcase 1 so as to penetrate in the vertical direction. A piston 6 that reciprocates in the cylinder axis direction is fitted in the bore 2 a of the cylinder 2 in FIG. 1, and the piston 26 and the crankshaft 5 are connected by a connecting rod 55.

  As shown in FIG. 2, a camshaft 7 is arranged in parallel to the crankshaft 5 in the crankcase 1a inside the crankcase 1, and an intake cam and an exhaust cam 71 formed on the camshaft 7. 72, the intake / exhaust valves (not shown) are driven via the tappet 73 and the rocker arm 74 of FIG. Rotational power is transmitted from the crankshaft 5 to the camshaft 7 by meshing between a gear 7 a provided on the shaft end side thereof and a crank gear 5 a provided on the crankshaft 5.

  FIG. 3 shows an enlarged longitudinal sectional view of the air cleaner 3. The air cleaner 3 includes a case 30 including first and second case halves 31 and 32, and a blow-by that forms a part of a breather passage, which will be described later, in the middle portion in the vertical direction of the side wall 31 a of the first case half 31. An inlet / outlet portion 34 is formed at the upper portion of the side wall 31a. In addition, an air intake 35 for introducing air A into the air cleaner 3 is formed in the lower portion of the side wall 31a of the first case half 31. The air A taken in from the intake 35 is transferred to the second case half. The air is purified from the introduction passage 36 formed in the lower part of the body 32 to the cleaner element 50 housed in the element housing chamber 32 a in the second case half 32, and the air A is purified when passing through the cleaner element 50. Thus, the purified air A is sent from the intake outlet 34 to the vaporizer 4.

  Further, as shown in FIG. 2, a breather passage 8 is formed between the crank chamber 1 a in the crankcase 1 and the air cleaner 3. As the breather passage 8, in this embodiment, a breather chamber 80 defined by an outer wall 1b of the crankcase 1 and a partition wall 1c is formed on the side of the camshaft 7 in the crank chamber 1a. An upstream passage portion 8A is formed between the crank chamber 1a and a downstream passage portion 9A is formed between the breather chamber 80 and the air cleaner 3.

  FIG. 4 is an enlarged longitudinal sectional view showing the breather passage 8. The upstream passage portion 8A of the breather passage 8 has a diameter close to a hollow portion 80 provided in the axial direction (vertical direction in the drawing) inside the camshaft 7 and an intake cam 71 on the upper side of the camshaft 7. A first lateral hole 81 formed in the direction and communicating with the hollow portion 80, and a hollow portion formed radially in the upper end bearing portion of the camshaft 7 above the first lateral hole 81. 80, a second hole 82 communicating with 80, and a bearing portion 1d of the crankcase 1 supporting the upper end of the camshaft 7 so as to face the first hole 81. And a third hole 83 that opens.

  The upstream passage portion 8A includes a second hole 82 in the upper end bearing portion of the camshaft 7 and a crankcase during the intake stroke in which the piston 6 (FIG. 1) descends, that is, when the pressure in the crank chamber 1a rises. When the third hole 83 of the first bearing portion 1d faces the blow-by gas G in the crank chamber 1a from the first lateral hole 81 to the hollow portion 80, the second lateral hole 82, and The air flows into the breather chamber 80 through the third lateral hole 83. The blow-by gas G does not flow into the breather chamber 80 because the second lateral hole 82 and the third lateral hole 83 do not communicate except in the intake process. The oil component separated in the breather chamber 80 returns to the crank chamber 1a through the recovery path 84.

  Further, the downstream passage portion 9A of the breather passage 8 includes an in-cylinder passage portion 91 extending from the breather chamber 80 through the cylinder 2 and the cylinder head 21 in FIG. 1 and an outlet side end portion 91a of the passage portion 91. And a breather pipe 92 made of a resin piped between the inlet 33 of the blow cleaner gas G of the air cleaner 3, and the blowby gas G flowing into the breather chamber 80 is in a cylinder passage portion as indicated by an arrow. It flows out toward the air cleaner 3 through 91 and the breather pipe 92.

  5 is a side view showing the inner surface of the first case half 31 of the cleaner case 30, and FIG. 6 is a perspective view thereof. An intake outlet portion 34 for sending the intake air purified by the cleaner element 50 to the carburetor 4 (FIG. 3) is located at a lateral position below the central portion of the upper side wall 31a of the first case half 31 in FIG. In addition, an inlet 33 for the blow-by gas G is formed, and an air intake 35 is formed at the lower end position. The first case half 31 is formed with a passage bending portion 93 that is curved from the periphery of the inlet portion 33 toward the intake outlet portion 34 and becomes a part of the downstream passage portion 9A.

  In this embodiment, a zigzag passage 94 is formed in which the blow-by gas G is passed through the curved passage portion 93 in a zigzag manner, and moisture contained in the blow-by gas G is separated and removed by inertial force. That is, on the side wall 31a of the first case half 31 shown in FIG. 6, a substantially U-shaped rising wall 93a having a side that extends in a curved shape from the inlet 33 toward the intake outlet 34 is formed. A plurality of plate members 93b extending alternately in different directions inwardly project from the opposing wall portions of the rising wall 93a, and the rising wall 93a and the plate member 93b, and the open side of the rising wall 93a The zigzag passage 94 is formed in an internal space surrounded by a passage cover 96 which will be described later.

  Further, on the upstream side of the zigzag passage 94 in the passage bending portion 93, the blow-by gas is separated from the blow-by gas G by notching the lowest part of the rising wall 93 a at a position below the blow-by gas inlet 33. A drain hole 95 is formed for discharging the moisture in the case 30.

  7 is a side view showing a state in which the open side of the rising wall 93a is closed by the passage cover 96 to form the curved passage portion 93, and FIG. 8 is a perspective view of the passage cover 96 as seen from the back side. The passage cover 96 of FIG. 8 is curved in the same manner as the rising wall 93a (FIG. 5) and covers the flat plate-like first member 96a covering the outside of the open side and the outside of the intake outlet 34 (FIG. 5). A rectangular flat plate-like second member 96b and a rectangular connecting cylinder provided between the first and second members 96a and 96b and having one end connected to the gas outlet 93c (FIG. 5) of the rising wall 93a. The connecting tube 96c is formed with a tube portion 96d that partially enters the intake outlet portion 36.

FIG. 9 is a side view showing the outer surface of the first case half 31, and FIG. The breather pipe 92 is connected to the inlet 33 of FIG. 9, as shown in FIG. A seal member 92a made of an O-ring is attached to the outer peripheral portion of the end of the pipe 92. The seal member 92a seals between the inlet portion 33 and the pipe 92. As shown in FIG. 9, a protrusion 37 is integrally formed with the first case half 31 so as to reach a substantially intermediate height position from the upper portion of the inlet 33, as shown in FIG. The drain hole 95 is formed at a position immediately downstream of the portion 37. The protruding portion collides with blow-by gas G to separate and remove moisture.

  FIG. 11 is a longitudinal sectional view showing a second case half 32 attached to the opening side portion of the first case half 31 of the air cleaner 3. At the lower end of the second case half 32, an engaging portion 39 is formed which is inserted into and engaged with an engaging portion 38 provided at the lower end of the first case half 31. At the upper end of the body 32, a locking claw 41 is formed which is inserted into the insertion hole 40 a of the locking tool 40 provided at the upper end of the first case half 31. Further, an engaging portion 41a is integrally formed on the upper portion of the locking claw 41. On the other hand, a locking portion for locking the engaging portion 41a is provided above the insertion hole 40a into which the locking claw 41 is inserted. The portion 40 b is integrally formed with the first case half 31. When the first and second case halves 31 and 32 are assembled, the first case half 31 is engaged with the engagement portion 38 of the second case half 32 and the second case half 32 is engaged with the first case half 31 and 32. The locking claw 41 of the two case half 32 is inserted inward from the insertion hole 40a of the locking tool 40 provided in the first case half 31, and the engaging portion 41a of the locking claw 41 is inserted into the insertion hole 40a. The locking portion 40b is locked (FIG. 3).

Next, the operation of the breather structure configured as described above will be described.
The blow-by gas G that has flowed into the crank chamber 1a from the combustion chamber 22 through the gap between the piston 6 and the inner wall surface of the liner 23 of the cylinder 2 based on the pressure fluctuation in the crank chamber 1a accompanying the reciprocation of the piston 6 in FIG. Is introduced into the breather chamber 80 through the upstream passage portion 8A of the breather passage 8 of FIG.

  The introduced blow-by gas G is decelerated and depressurized in the breather chamber 80, whereby oil components such as oil mist are separated and removed, and the oil components are returned from the recovery path 84 into the crank chamber 1a. The blow-by gas G from the breather chamber 80 passes through the downstream passage portion 9A of the breather passage 8 of FIG. 1 and is sent to the downstream side of the cleaner element 50 in the air cleaner 3 of FIG.

  When the blowby gas G is sent to the intake outlet 34 through the downstream passage portion 9A of the breather passage 8, the downstream passage portion 9A has an inlet portion 33 in the first case half 31 shown in FIG. Since a passage bending portion 93 that curves toward the intake outlet portion 34 is provided from around the center, moisture having a large specific gravity collides with the inner surface of the passage by centrifugal force from the blowby gas G passing through the passage bending portion 93, Separated and removed. In particular, since the zigzag passage 94 is formed from the inlet portion 33 toward the intake outlet portion 34, the blowby gas G is included in the blowby gas G by colliding with each plate member 93b provided in the passage 94. Water is better separated and removed.

  Further, as shown in FIG. 10, since the protrusion 37 is formed at the back of the inlet portion 33 of the first case half 31 to which the breather pipe 92 is connected, the blow-by gas G from the breather pipe 92 is By colliding with the projections 37, the water mixed in the blow-by gas G is separated and removed even better.

  In this way, the water separated and removed from the blow-by gas G is discharged into the first case half 31 from the drain hole 95 formed at the lower position of the passage bending portion 93. The blow-by gas G from which moisture has been separated and removed is returned to the combustion chamber 22 in FIG. 1 from the intake outlet 34 through the carburetor 4 together with the purified air that has passed through the cleaner element 50 in FIG. Reburned.

  Next, a breather structure according to a second embodiment of the present invention will be described. FIG. 12 is a side view showing the inner surface of the first case half 31 of the air cleaner in which the breather passage according to the second embodiment is formed, and FIG. 13 is a perspective view thereof. An element accommodating chamber 31b for accommodating the cleaner element 50 is formed inside the first case half 31 shown in FIG. 12, and is located above the center case in the left-right direction and outward from the side wall 31a of the first case half 31. An inlet portion 33 of the protruding blow-by gas is formed at a position near the lower portion of the inlet portion 33, and an intake outlet portion 34 is formed. In addition, an air intake 35 is formed at an upper side position of the storage chamber 31b, and the air A taken in from the air intake 35 is purified by being introduced into the storage chamber 31b and passing through the cleaner element 50, The purified air A enters the outlet chamber 31d through a passage 46 between a plurality of projecting plates 45 protruding between the intake outlet portion 34 and the storage chamber 31b, and enters the carburetor 4 from the intake outlet portion 34. (FIG. 3) sent to the side. On the side wall 31a of the first case half 31 around the accommodation chamber 31b, the inlet portion 33 and the intake outlet portion 34, a seal wall 31c for sealing between the second case (not shown) is projected. The second case is attached to the first case half 31 via the plurality of attachments 31e shown in FIG. 13, and the storage chamber 31b and the outlet chamber 31d are sealed from the outside in the seal wall 31.

  14 is a cross-sectional view seen from the direction of the XIV-XIV line in FIG. As shown in FIG. 14, a breather pipe 92 extending from the cylinder 2 is connected to the outside of the inlet 33 of the blow-by gas G. The breather pipe 92 extends upward from the outlet side end portion 91 a of the cylinder head 21, and has a substantially L shape that is bent and horizontal at the introduction portion 92 a before the inlet portion 33. A U-shaped duct 96 forming a curved passage portion 93 is provided between the inside of the inlet portion 33 and the intake outlet portion 34, and a lower portion of a connection portion between the duct 96 and the inlet portion 33. On the side, a drain hole 95 is formed through which moisture separated and removed from the blow-by gas G is discharged into the first case half 31. Also in this embodiment, a protrusion 37 that separates and removes moisture by colliding with the blow-by gas G is formed inside the inlet 33 to which the breather pipe 92 is connected. The drain hole 95 is provided.

  The duct 96 includes a large-diameter portion 96a attached to a connecting portion to the inlet portion 33, a duct main body 96b that is gradually squeezed from the large-diameter portion 96a while being curved in a U shape, and a distal end of the main body 96b. A small-diameter portion 96c that is formed and partially enters the intake outlet portion 34. The duct 96 is composed of two halved cylindrical dividing members, and is connected to each other by a plurality of connecting members 96d provided therein, and is formed in a cylindrical shape.

  As shown in FIG. 15 which is an enlarged side view, an inner cylinder 47 and an outer cylinder 48 are concentrically provided on the connecting portion of the duct 96 on the side wall 31a of the first case half 31 so as to project the inner and outer cylinders. A large diameter portion 96a of the duct 96 shown in FIG. 14 is inserted into the groove 49 between the tubes 47 and 48 and fixed. Further, in FIG. 15, the lower side of the duct 96 in the outer cylinders 47 and 48 on the connection base portion side is opened, and this open portion is the drain hole 95.

  In the above configuration, when the blow-by gas G shown in FIG. 14 reaches the air cleaner 3 from the breather pipe 92 through the inlet portion 33, the blow-by gas G collides with the protrusion 37 provided in the inner portion of the inlet portion 33 and becomes blow-by gas. The mixed water is separated and removed. Further, since a duct 96 curved in a U-shape is disposed between the inlet portion 33 and the intake outlet portion 34, the blowby gas G has a large specific gravity when passing through the curved portion of the duct 96. Moisture collides with the inner surface of the duct 96 by centrifugal force and is separated and removed. Further, since the introduction portion 92a of the breather pipe 92 is also curved, moisture is separated and removed also at this portion. The moisture removed in this way is discharged into the first case half 31 from a drain hole 95 formed at a position below the connecting portion between the duct 96 and the inlet 33. The blow-by gas G from which moisture has been removed is returned to the combustion chamber 22 from the intake outlet 34 through the vaporizer 4 of FIG. 1 together with the air that has passed through the cleaner element 50 and purified, and is recombusted.

1 is a partially cutaway plan view showing an engine to which a breather structure according to a first embodiment of the present invention is applied. It is a longitudinal cross-sectional view along the II-II line of FIG. It is a longitudinal cross-sectional view which expands and shows the part of an air cleaner. It is a longitudinal cross-sectional view which expands and shows the part of a breather channel | path. It is a side view which shows the inner surface of the case (1st case half body) of an air cleaner. It is the same perspective view. It is a side view which shows the state which attached the channel | path cover to the curved channel | path part. It is the perspective view which looked at the channel | path cover from the back side. It is a side view which shows the outer surface of the case (1st case half body) of an air cleaner. FIG. 6 is a cross-sectional view taken along line XX in FIG. 5. It is a longitudinal cross-sectional view which shows the case (2nd case half body) of an air cleaner. It is a side view which shows the inner surface of the case (1st case half body) of the air cleaner which formed the breather channel | path concerning 2nd Embodiment of this invention. It is the same perspective view. It is sectional drawing seen from the XIV-XIV line direction of FIG. It is a side view which expands and shows the connection part of a duct by the side wall of a case (1st case half body).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a ... Crank chamber 3 ... Air cleaner 30 ... Case 31 ... 1st case half 32 ... 2nd case half 33 ... Inlet part 34 ... Intake outlet part 37 ... Protrusion part 50 ... Cleaner element 8 ... Breather passage 93 ... Passage curved part 94 ... Zigzag passage 95 ... Drain hole 96 ... Duct A ... Air G ... Blow-by gas

Claims (4)

A breather passage for communicating the crank chamber with the downstream side of the cleaner element inside the air cleaner;
An inlet portion provided in a case of an air cleaner in the breather passage and an intake outlet portion of the case are connected by a curved passage curved portion,
A breather structure for an engine in which a drain hole for discharging moisture separated from blow-by gas passing through a breather passage into the case is formed in the passage curved portion. 2. The breather structure for an engine according to claim 1, wherein a projection portion where blow-by gas collides is formed at the inlet portion. 3. The inlet portion according to claim 1, wherein the inlet portion is located below the intake outlet portion, and a passage for changing the flow direction of blow-by gas to a zigzag is formed in the passage curved portion, and the lowest portion of the inlet portion A breather structure for an engine in which the drain hole is formed in a portion. 3. The inlet portion according to claim 1 or 2, wherein the inlet portion is located in the vicinity of the intake outlet portion, the passage curved portion is formed by a U-shaped duct, and the lower portion of the connecting portion between the duct and the inlet portion Engine breather structure with a drain hole.

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