JP2013007275A - Gas-liquid separation structure for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small gas-liquid separation structure for an engine with high gas-liquid separation performance.SOLUTION: A first path (D1) is provided in a shaft part (181) of a balancer shaft (180). A second path (D2 )communicating with the first path( D1) is provided in a weight part (182). The first path communicates with the outside of the balancer shaft (180) via a hole (H2) provided in the shaft part (181). The second path (D2) communicates with the outside of the balancer shaft (180) via a hole( H3) provided in the weight part (182). By separating a gas-liquid mixture flowing into the second path (D2 )from the hole (H3) provided in the weight part (182 )into a liquid and a gas according to rotation of the balancer shaft (180), the separated gas is discharged to the outside of the balancer shaft (180 )from the hole (H2) of the shaft part (181) through the first path (D1).

Description

  The present invention relates to a gas-liquid separation structure for an engine applied to, for example, a motorcycle.

  Inside the engine, the blow-by gas that leaks from the combustion chamber into the crankcase through the gap between the piston and the cylinder is not exhausted through the exhaust port but is accumulated in the crankcase. When blow-by gas accumulates in the crankcase in this way, it can cause oil deterioration and metal corrosion.In general, the blow-by gas is introduced into the intake port, burned in the combustion chamber, and released into the atmosphere. Yes.

  Due to the structure of the engine, mist-like liquid such as engine oil is mixed with blow-by gas. For this reason, a gas-liquid separation structure called a breather chamber or the like may be provided so that a liquid such as engine oil can be separated from blow-by gas (see, for example, Patent Document 1). In Patent Document 1, blow-by gas mixed with engine oil is guided to a breather chamber (breather) installed outside the crankcase, separated into gas and liquid in the breather chamber, and the separated gas is brought to the intake port side. The discharged and separated liquid is returned to the crankcase.

JP 2007-132255 A

  However, in the above-described breather chamber, gas-liquid separation is performed by adhering the liquid mixed in the blow-by gas to the wall surface of the breather chamber, so that the amount of blow-by gas and engine oil is low as in an engine with a large displacement. Increasing the number requires a large breather chamber for proper gas-liquid separation. When a large-sized breather chamber is used, there arises a problem that the engine unit becomes large as a result.

  This invention is made | formed in view of this point, and it aims at providing the gas-liquid separation structure of the engine which has a small and high gas-liquid separation performance.

  An engine gas-liquid separation structure according to the present invention includes a crankshaft rotatably supported in a crank chamber provided in a crankcase, and a balancer shaft configured to rotate according to the rotation of the crankshaft. The balancer shaft includes a shaft portion serving as a rotation shaft, and a weight portion extending radially outward of the shaft portion on one end side of the shaft portion, and a first passage in the shaft portion A second passage communicating with the first passage is provided in the weight portion, and the first passage communicates with the outside of the balancer shaft through a hole provided in the shaft portion. The second passage communicates with the outside of the balancer shaft through a hole provided in the weight portion, and the gas-liquid mixture flowing into the second passage from the hole provided in the weight portion is transferred to the balancer shaft. Times By separating the liquid and gas, characterized in that it is configured to separated gas is discharged from the hole of the shaft portion through the first passageway to the outside of the balancer shaft.

  According to this configuration, since the gas-liquid separation of the gas-liquid mixture flowing into the passage in the balancer shaft is promoted by the rotation of the balancer shaft, a gas-liquid separation structure having a small size and high gas-liquid separation performance can be realized.

  In the gas-liquid separation structure for an engine according to the present invention, it is preferable that the balancer shaft is disposed above the crankshaft. According to this configuration, a large amount of engine oil scattered by the crankshaft can be prevented from entering the balancer shaft passage from the hole provided in the weight portion of the balancer shaft.

  In the gas-liquid separation structure of an engine according to the present invention, a breather chamber including a first breather chamber in which the shaft portion of the balancer shaft is accommodated, and a second breather chamber above the first breather chamber. The first breather chamber and the second breather chamber communicate with each other through a hole provided in a wall separating the first breather chamber, and the second breather chamber communicates with the outside through a discharge port. It is preferable that the gas discharged to the outside of the balancer shaft is discharged to the outside from the discharge port through the first breather chamber and the second breather chamber. According to this configuration, since the breather chamber is constituted by the first breather chamber through which the balancer shaft is inserted and the second breather chamber above the first breather chamber, the engine oil enters the passage of the balancer shaft. Even in this case, leakage of engine oil from the breather chamber can be prevented.

  In the gas-liquid separation structure of the engine of the present invention, it is preferable that the gas discharged from the exhaust port is guided to the intake port. According to this configuration, the gas-liquid mixture can flow more smoothly into the balancer shaft passage by the negative pressure on the intake side. Thereby, a high gas-liquid separation effect can be obtained.

  In the gas-liquid separation structure for an engine according to the present invention, in the motorcycle in which the down tube of the main frame branches to the left and right lower frames by arranging the breather chamber in front of the crank chamber, the breather chamber It is preferable that the outer wall is configured to be exposed between the left and right lower frames. According to this configuration, since the outer wall of the breather chamber is exposed between the lower frames, the breather chamber and the balancer shaft inserted into the breather chamber can be cooled by the air flowing between the lower frames. Thereby, a high gas-liquid separation effect can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the gas-liquid separation structure of the engine which has a small and high gas-liquid separation performance can be provided.

1 is a side view showing an appearance of a motorcycle according to the present embodiment. It is a side view which shows the external appearance of the engine unit which concerns on this Embodiment. It is a fragmentary sectional view of the engine unit concerning this embodiment. It is a disassembled perspective view of the engine unit which concerns on this Embodiment. It is a side view which shows a part of left side surface of the crankcase which concerns on this Embodiment. It is a side view which shows a part of right side surface of the crankcase which concerns on this Embodiment. It is sectional drawing of the crankcase which concerns on this Embodiment. It is sectional drawing of the balancer shaft which concerns on this Embodiment. It is a perspective view which shows the structure around the breather chamber of the left crankcase according to the present embodiment. It is the figure which looked at the engine unit and vehicle body frame which concern on this Embodiment from the front.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following, an example in which the gas-liquid separation structure of an engine according to the present invention is applied to an engine of an off-road type motorcycle will be described, but the application target is not limited to this and can be changed. For example, the gas-liquid separation structure of the engine according to the present invention may be applied to engines of other types of motorcycles, four-wheeled vehicles, ships, and the like.

  A configuration of the entire motorcycle according to the present embodiment will be described. FIG. 1 is a left side view of the motorcycle according to the present embodiment. In the drawings, the front of the vehicle body is indicated by an arrow FR, and the rear of the vehicle body is indicated by an arrow RE.

  As shown in FIG. 1, the motorcycle 1 includes a body frame 2 made of steel or aluminum alloy on which the components of the motorcycle 1 are mounted. The main frame 21 of the vehicle body frame 2 branches from the head pipe 22 located at the front end of the vehicle body frame 2 to the left and right and extends obliquely downward toward the rear of the vehicle body. A down tube 23 extending substantially downward from the head pipe 22 branches to the left and right as a lower frame 24 in the vicinity of the lower part of the vehicle body. The left and right lower frames 24 are further extended downward and then bent toward the rear of the vehicle body, and their rear ends are connected to the left and right rear ends of the main frame 21 via the left and right body frames 25.

  A front fork 31 is rotatably supported at the front end of the vehicle body frame 2 via a steering shaft (not shown) provided in the head pipe 22. A handlebar 32 is coupled to the upper end of the steering shaft, and grips 33 are attached to both ends of the handlebar 32. A clutch lever 34 is disposed on the left front side of the handle bar 32, and a brake lever (not shown) for the front wheel 3 is disposed on the right front side of the handle bar 32. The front wheel 3 is rotatably supported at the lower portion of the front fork 31. The front wheel 3 is provided with a brake disc 35 that constitutes a brake for the front wheel.

  A swing arm 41 is connected to the body frame 25 of the body frame 2 so as to be swingable in the vertical direction, and a suspension 42 is attached between the body frame 2 and the swing arm 41. The rear wheel 4 is rotatably supported at the rear portion of the swing arm 41. A rear sprocket (driven sprocket) 43 is provided on the left side of the rear wheel 4, and the power of the engine is transmitted to the rear wheel 4 by a chain 44. On the right side of the rear wheel 4, a brake disk (not shown) that constitutes a brake for the rear wheel is provided.

  A water-cooled engine unit 10 serving as a drive source is mounted at a position near the lower side of the space substantially surrounded by the main frame 21, the down tube 23, the lower frame 24, and the body frame 25 of the vehicle body frame 2. A radiator 5 that is a radiator is disposed in front of the engine unit 10, and an air cleaner box 6 having a filter that separates and collects dust in the air is disposed behind the engine unit 10. A fuel tank 7 in which fuel is stored is disposed above the engine unit 10, and a seat 8 serving as a seat is disposed behind the fuel tank 7. A footrest 81 is provided below the seat 8. A shift pedal 82 is provided in front of the footrest 81 on the left side of the vehicle body, and a brake pedal (not shown) for the rear wheel 4 is provided in front of the footrest 81 on the right side of the vehicle body.

  The engine unit 10 includes a horizontal crank type four-stroke (four-cycle) single-cylinder engine and a transmission (transmission) in which the rotation shaft of the crankshaft is arranged in parallel to the vehicle width direction. Air is taken into the engine unit 10 through the air cleaner box 6, the intake pipe 170 (see FIG. 2), etc., and the air and fuel are mixed by the fuel injection device and supplied to the combustion chamber 123 (see FIG. 3). . The combustion gas after combustion is discharged as exhaust gas from the muffler 101 through an exhaust pipe (not shown) extending rearward on the right side surface of the engine unit 10.

  Next, the outline of the engine unit 10 provided with the gas-liquid separation structure according to the present embodiment will be described. FIG. 2 is a side view showing an overall configuration of engine unit 10 according to the present embodiment. FIG. 3 is a partial cross-sectional view of engine unit 10 according to the present embodiment. FIG. 4 is an exploded perspective view of the engine unit 10 according to the present embodiment. In FIG. 4, a part of the configuration is omitted.

  As shown in FIG. 2, in the engine unit 10, a cylinder 120 having a substantially cylindrical shape is disposed on a crankcase 110, and a cylinder head 130 and a head cover 140 are attached to the cylinder 120. A magnet cover 150 is attached to the left side surface of the crankcase 110. Further, as shown in FIG. 4, a clutch cover 160 is attached to the right side surface of the crankcase 110. The crankcase 110 includes a right crankcase 110R and a left crankcase 110L that are divided into left and right in a plane perpendicular to the vehicle width direction. A crank chamber 111 is provided between the right crankcase 110R and the left crankcase 110L.

  As shown in FIG. 3, a crankshaft 112 is accommodated in a crank chamber 111 in the crankcase 110 so that the rotation shaft is arranged in parallel to the vehicle width direction. A piston 121 is accommodated in a cylindrical space inside the cylinder 120 so as to reciprocate in the cylinder axis direction (vertical direction). The piston 121 and the crankshaft 112 are connected via a connecting rod (connecting rod) 122 so that the reciprocating motion of the piston 121 is converted into the rotational motion of the crankshaft 112. The piston 121 is connected to the small end portion of the connecting rod 122, and the crankshaft 112 is connected to the large end portion of the connecting rod 122.

  In the cylinder head 130, there are an intake port 131 that sends air into the combustion chamber 123 surrounded by the inner wall surface of the cylinder 120, the lower surface of the cylinder head 130, and the upper surface of the piston 121, and an exhaust port that discharges combustion gas outside the combustion chamber 123. 132 is formed. Further, the cylinder head 130 is provided with an intake valve 133 for opening and closing the intake port 131 and an exhaust valve 134 for opening and closing the exhaust port 132. An ignition plug (not shown) is disposed on the lower surface of the cylinder head 130 so as to protrude, and the air-fuel mixture in the combustion chamber 123 can be ignited by electric discharge.

  In the engine unit 10 operating in four strokes, when the piston 121 descends, the intake valve 133 is opened, and the air-fuel mixture is sent into the combustion chamber 123 through the intake pipe 170 and the intake port 131 (intake stroke). Thereafter, the intake valve 133 is closed, and the piston 121 rises to compress the air-fuel mixture (compression stroke). When the piston 121 reaches the top dead center, the air-fuel mixture that is ignited and compressed by the spark plug burns (combustion stroke). When the pressure in the combustion chamber 123 increases due to the combustion of the air-fuel mixture, the piston 121 descends. The downward movement of the piston 121 is transmitted to the crankshaft 112 via the connecting rod 122, and the crankshaft 112 rotates. Thereafter, when the piston 121 descends to the bottom dead center and starts to rise again due to inertia, the exhaust valve 134 is opened and the combustion gas is discharged from the exhaust port 132 (exhaust stroke). A valve operating device including an intake valve 133 and an exhaust valve 134 is provided on the upper portion of the cylinder head 130 to enable such an operation.

  The intake / exhaust mechanism of the engine unit 10 is a DOHC (Double Overhead Camshaft) having two independent camshafts on the intake side and the exhaust side. The two camshafts are each provided with a cam having a shape corresponding to the opening / closing timing of the corresponding intake valve 133 or exhaust valve 134, and the rotation shaft of the camshaft is parallel to the vehicle width direction in the upper part of the cylinder head 130. It is arranged to be. One end of the camshaft is connected to the crankshaft 112 via a power transmission mechanism such as a sprocket or cam chain. Thereby, the rotational force of the crankshaft 112 is transmitted to the camshaft, and the intake valve 133 and the exhaust valve 134 are opened and closed to correspond to the rotation of the crankshaft 112.

  As shown in FIG. 4, the engine unit 10 includes a balancer shaft 180 coupled to the crankshaft 112 so as to rotate in accordance with the rotation of the crankshaft 112. The balancer shaft 180 includes a shaft portion 181 serving as a rotation shaft, and a weight portion 182 that extends outward in the radial direction of the shaft portion 181 at one end portion of the shaft portion 181. A balancer gear 183 that meshes with a gear 162 provided at one end of the crankshaft 112 is attached to the other end of the balancer shaft 180, and the balancer shaft 180 rotates in accordance with the rotation of the crankshaft 112. ing. The weight portion 182 and the balancer gear 183 are configured such that the position of the center of gravity deviates from the rotation axis. As a result, the balancer shaft 180 and the balancer gear 183 rotate in accordance with the rotation of the crankshaft 112, so that the primary vibration due to the reciprocating motion of the piston 121 and the connecting rod 122 is alleviated.

  The balancer shaft 180 is disposed such that a shaft portion 181 penetrates the first breather chamber 116 provided in front of the crankcase 110 in the vehicle width direction. A second breather chamber 117 is provided above the first breather chamber 116. The first breather chamber 116 and the second breather chamber 117 communicate with each other through a hole H1 provided in a partition wall separating them, and the second breather chamber 117 is connected through a discharge port 118 provided in a front wall. And communicate with the outside. A discharge pipe 119 is disposed at the discharge port 118.

  The surfaces of the movable parts such as the piston 121 and the crankshaft 112 described above and the parts such as the cylinder 120 that come into contact with the movable parts are lubricated with engine oil in order to prevent wear. The engine oil that has lubricated the piston 121, the crankshaft 112, the cylinder 120, etc. falls due to gravity and collects at the bottom of the crank chamber 111. As shown in FIGS. 3 and 4, an oil storage chamber 113 is provided at the bottom of the crank chamber 111 to store the engine oil dropped in this way. In addition to lubrication, engine oil has functions such as cooling, airtight maintenance, cleaning, and rust prevention.

  In the crankcase 110, the oil storage chamber 113 at the bottom of the crank chamber 111 communicates with the oil passage 114 via a reed valve 113a. Further, the oil passage 114 communicates with the left magneto chamber 151 of the crankcase 110 through a hole (not shown) provided in the wall of the left crankcase 110L shown in FIG. Engine oil in the oil storage chamber 113 is discharged to the magneto chamber 151 through the oil passage 114. The engine oil accumulated at the bottom of the magneto chamber 151 is pumped up by an oil pump (scavenge pump) 152 and supplied to the transmission chamber 115. An oil pump (feed pump) (not shown) having a rotating shaft that rotates in synchronization with the oil pump 152 is arranged in the transmission chamber 115 so that engine oil can be supplied to each part of the engine unit 10 through an oil passage (not shown). It has become.

  As described above, the inner wall of the cylinder 120, the surface of the piston 121, and the like are lubricated by the engine oil, and the airtightness of the combustion chamber 123 is maintained. However, when the pressure in the combustion chamber 123 increases due to combustion of the air-fuel mixture or the like, blow-by gas may leak from the combustion chamber 123 into the crank chamber 111 through the gap between the inner wall of the cylinder 120 and the piston 121. This blow-by gas contains a combustion gas after combustion in addition to an air-fuel mixture (fuel and air), and mist-like engine oil or the like is mixed.

  The blow-by gas is discharged to the magneto chamber 151 through the oil passage 114 in the same manner as the engine oil. The blow-by gas discharged to the magnet chamber 151 is usually separated from a liquid such as engine oil through a breather chamber and the like, and then released to the atmosphere. However, in the breather chamber that performs gas-liquid separation using the principle that liquid adheres to the wall surface, the gas-liquid separation effect depends on the size of the breather chamber (more specifically, the area of the inner wall surface, etc.) In applications where there is a large amount of blowby gas or engine oil, a large breather chamber is required. When a large breather chamber is used, there arises a problem that the engine unit becomes large.

  Therefore, in the gas-liquid separation structure according to the present embodiment, the balancer shaft 180 that rotates in accordance with the rotation of the crankshaft 112 is used, and the mixture of blowby gas and engine oil is obtained by the centrifugal separation effect caused by the rotation of the balancer shaft 180. The gas-liquid mixture is gas-liquid separated. In addition, gas-liquid separation is further promoted by the first breather chamber 116 and the second breather chamber 117. Thereby, the gas-liquid separation structure which has a small and high gas-liquid separation performance is realizable. Hereinafter, the gas-liquid separation structure according to the present embodiment will be described in detail.

  As shown in FIG. 4, a plurality of walls defining each chamber of the crankcase 110 are provided on the left and right sides of the right crankcase 110R and the left crankcase 110L so as to extend in the vehicle width direction. A wall W1 provided on the left side of the right crankcase 110R and a wall W2 provided on the right side of the left crankcase 110L are joined together to form a crank chamber 111, an oil storage chamber 113, an oil passage 114, and a transmission chamber in the crankcase 110. 115, a first breather chamber 116, a second breather chamber 117, and the like are formed. A crankshaft 112 is disposed in the crank chamber 111 so that the rotation shaft is parallel to the vehicle width direction. In the first breather chamber 116, the shaft portion 181 of the balancer shaft 180 is disposed so that the rotation axis is parallel to the vehicle width direction.

  The wall provided on the left side of the left crankcase constitutes a magneto wall LW1 that partitions the magneto chamber 151, and a magneto cover 150 is attached to the left end of the magneto wall LW1. A weight 182 of the balancer shaft 180 is disposed in front of the magneto chamber 151. An oil pump 152 for pumping up engine oil accumulated at the bottom of the magneto chamber 151 and supplying it to the transmission chamber 115 is disposed behind the magneto chamber 151. The wall provided on the right side of the right crankcase constitutes a clutch wall RW1 that partitions the clutch chamber 161, and a clutch cover 160 is attached to the right end of the clutch wall RW1. A gear 162 attached to the crankshaft 112 and a balancer gear 183 attached to the balancer shaft 180 are disposed in the clutch chamber 161, and the balancer shaft 180 rotates according to the rotation of the crankshaft 112. ing.

  FIG. 5 is a side view showing a part of the left side surface of left crankcase 110L according to the present embodiment. As shown in FIG. 5, a magnet wall LW <b> 1 that constitutes the outer shape of the left front of the crankcase 110 is provided at the left front position of the left crankcase 110 </ b> L so as to extend in the vehicle width direction. A magneto cover 150 (see FIG. 4) is joined to the left side of the magneto wall LW1, and a magneto chamber 151 is formed by the magneto wall LW1 and the magneto cover 150.

  In the vicinity of the center of the magnet chamber 151, a part of the left side surface of the crankshaft 112 is exposed, and a magnet rotor (not shown) constituting the generator is connected to the left side surface of the crankshaft 112. A weight portion 182 of the balancer shaft 180 is disposed in front of and above the crankshaft 112, and the weight portion 182 in the magneto chamber 151 rotates in accordance with the rotation of the balancer shaft 180. In addition, in the magneto chamber 151, an oil pump 152 and a stator coil (not shown) constituting a generator are arranged.

  FIG. 6 is a side view showing a part of the right side surface of right crankcase 110R according to the present embodiment. As shown in FIG. 6, on the right side of the right crankcase 110R, a clutch wall RW1 constituting the outer shape of the right side of the crankcase 110 is provided so as to extend in the vehicle width direction. A clutch cover 160 (see FIG. 4) is joined to the right side of the clutch wall RW1, and a clutch chamber 161 is formed by the clutch wall RW1 and the clutch cover 160.

  In the clutch chamber 161, a part of the right side surface of the crankshaft 112 is exposed, and a gear 162 is attached to the right side surface of the crankshaft 112. A balancer gear 183 attached to the balancer shaft 180 is disposed at a position in front of and above the crankshaft 112. When the gear 162 and the balancer gear 183 are engaged with each other, the balancer shaft 180 is rotated according to the rotation of the crankshaft 112.

  FIG. 7 is a cross-sectional view of the crankcase 110 according to the present embodiment. FIG. 7 corresponds to a cross section taken along the line AA in FIG. 5 and FIG. 6 (when viewed from the front). In FIG. 7, the right side of the vehicle body is indicated by an arrow R, and the left side of the vehicle body is indicated by an arrow L. As shown in FIG. 7, a right breather wall RW2 extending in the vehicle width direction is provided on the front left side of the right crankcase 110R so as to form a certain space. A left breather wall LW2 extending in the vehicle width direction is provided on the right front side of the left crankcase 110L so as to form a certain space. By joining the right breather wall RW2 and the left breather wall LW2, a breather wall BW that defines the outer edges of the first breather chamber 116 and the second breather chamber 117 is formed.

  A right partition wall RW3 extending in the vehicle width direction is provided in a region surrounded by the breather wall BW on the left side of the right crankcase 110R. A left partition wall LW3 extending in the vehicle width direction is provided in a region surrounded by the breather wall BW on the right side of the left crankcase 110L. By joining the right partition wall RW3 and the left partition wall LW3, a partition wall PW that partitions the first breather chamber 116 and the second breather chamber 117 is configured.

  A right bearing portion 116 a is provided on the right wall of the first breather chamber 116. A left bearing portion 116 b is provided on the left wall of the first breather chamber 116. The balancer shaft 180 is disposed so as to penetrate the first breather chamber 116 in the left-right direction, and is rotatably supported by the right bearing portion 116a and the left bearing portion 116b. The magnet chamber 151 on the left side of the first breather chamber 116 is provided with a weight portion 182 of the balancer shaft 180. The clutch chamber 161 on the right side of the first breather chamber 116 has a balancer gear 183 connected to the balancer shaft 180. Is arranged.

  A hole H1 is formed in the partition wall PW that separates the first breather chamber 116 and the second breather chamber 117, and the first breather chamber 116 and the second breather chamber 117 communicate with each other through the hole H1. . The second breather chamber 117 communicates with the outside through a discharge port 118 formed in the left breather wall LW2 and a discharge pipe 119 disposed in the discharge port 118 (see FIG. 4 and the like). Thereby, the blow-by gas discharged to the first breather chamber 116 is discharged to the outside through the second breather chamber 117.

  FIG. 8 is a cross-sectional view of the balancer shaft 180 according to the present embodiment. As shown in FIG. 8, the balancer shaft 180 includes a shaft portion 181 serving as a rotation shaft, and a weight portion 182 that extends outward in the radial direction of the shaft portion 181 on one end side of the shaft portion 181. . A first passage D <b> 1 extending in the rotation axis direction of the balancer shaft 180 is formed in the shaft portion 181. A cap (blind plug) 181a is provided at the end of the first passage D1 on the weight portion 182 side so as to close one end of the first passage D1. A hole H2 is formed in the side wall of the first passage D1 in the shaft portion 181, and the first passage D1 communicates with the outside of the balancer shaft 180 through the hole H2. Since the balancer shaft 180 is disposed in the first breather chamber 116 so that the hole H2 is located in the first breather chamber 116, the first passage D1 and the first breather chamber 116 communicate with each other through the hole H2. (See FIG. 7 and the like).

  A second passage D2 that communicates with the first passage D1 is provided in the weight portion 182 at the end of the shaft portion 181 on the magnet chamber 151 side. The second passage D2 is provided so as to extend in a direction perpendicular to the rotation axis of the balancer shaft 180, and communicates with the outside of the balancer shaft 180 through a hole H3 provided in a wall constituting the outer periphery of the weight portion 182. ing. Since the weight portion 181 of the balancer shaft 180 is disposed in the magneto chamber 151, the second passage D2 and the magneto chamber 151 communicate with each other through the hole H3.

  That is, the magneto chamber 151 communicates with the second passage D2 through the hole H3, the second passage D2 communicates with the first passage D1, and the first passage D1 communicates with the first breather chamber through the hole H2. 116. The first breather chamber 116 communicates with the second breather chamber 117 through the hole H1, and the second breather chamber 117 communicates with the outside through the discharge port 118 (discharge pipe 119).

  In the gas-liquid separation structure configured as described above, when the blow-by gas is discharged to the magneto chamber 151 and the pressure of the magneto chamber 151 is increased as described above, the gas-liquid mixture of the blow-by gas and the engine oil is discharged to the discharge port 118 ( It tries to flow out from the discharge pipe 119). For this reason, the gas-liquid mixture in the magneto chamber 151 flows into the second passage D2 of the weight portion 181 through the hole H3. Since the balancer shaft 180 rotates in conjunction with the crankshaft 112, the gas-liquid mixture flowing into the second passage D2 is separated into gas and liquid by the rotational movement of the balancer shaft 180. The separated gas is discharged to the first breather chamber 116 through the first passage D1 and the hole H2. The separated liquid is returned to the magneto chamber 151 by centrifugal force generated by the rotational movement of the balancer shaft 180.

  As described above, the gas-liquid separation structure according to the present embodiment promotes the gas-liquid separation of the gas-liquid mixture flowing into the second passage D2 in the balancer shaft 180 using the rotational motion of the balancer shaft 180. High gas-liquid separation performance can be obtained even with a small size. Thereby, problems, such as enlargement of an engine, can be eliminated.

  FIG. 9 is a perspective view showing a part of the right side surface of the left crankcase 110L according to the present embodiment. As shown in FIG. 9, the gas separated by the centrifugal separation effect due to the rotational movement of the balancer shaft 180 flows into the first breather chamber 116 from the hole H <b> 2 of the balancer shaft 180. The gas flowing into the first breather chamber 116 is further gas-liquid separated in the first breather chamber 116 and flows into the second breather chamber 117 through the hole H1. The gas flowing into the second breather chamber 117 is further gas-liquid separated in the second breather chamber 117 and discharged from the discharge port 118 (discharge pipe 119). The gas exhausted from the exhaust port 118 (exhaust pipe 119) is guided to the intake port 131 by an exhaust pipe (not shown) or the like, and released into the atmosphere after combustion in the combustion chamber 123.

  Thus, in the gas / liquid separation structure according to the present embodiment, in addition to the gas / liquid separation effect by the rotation of the balancer shaft 180, the gas / liquid separation effect by the first breather chamber 116 and the second breather chamber 117 can be obtained. it can. For this reason, a sufficiently high gas-liquid separation effect is obtained. Even when engine oil enters the first passage D1 and the second passage D2 of the balancer shaft 180, the second breather chamber 117 is disposed above the first breather chamber 116, so that the engine oil leaks out. Can be suppressed.

  In addition, the gas-liquid separation structure according to the present embodiment has a balancer shaft 180 disposed above the crankshaft 112 as shown in FIGS. The oil can be prevented from entering the first passage D1 and the second passage D2. Thereby, clogging of the first passage D1 and the second passage D2 due to a large amount of engine oil can be suppressed, and a sufficient gas-liquid separation effect can be ensured. In addition, leakage of engine oil to the outside through the first passage D1 and the second passage D2 can be suppressed.

  Furthermore, since the gas-liquid separation structure according to the present embodiment is configured such that the gas discharged from the discharge port 118 (discharge pipe 119) is guided to the intake port 131, the balancer shaft 180 is caused by the negative pressure on the intake side. The gas-liquid mixture can flow more smoothly into the first passage D1 and the second passage D2. Thereby, a higher gas-liquid separation effect can be obtained.

  FIG. 10 is a schematic view of the body frame 2 and the engine unit 10 according to the present embodiment as viewed from the front. As shown in FIG. 10, an engine unit 10 is mounted on the lower part of the body frame 2. The down tube 23 of the vehicle body frame 2 branches downward into a right lower frame 24R and a left lower frame 24L, and the engine unit 10 has an outer wall in front of the crankcase 110 between the right lower frame 24R and the left lower frame 24L. Is arranged to be exposed. A clutch cover 160 is disposed between the right body frame 25R and the right lower frame 24R extending in the vertical direction on the right rear side of the engine unit 10. A magneto cover 150 is disposed between the left body frame 25L and the left lower frame 24L extending in the vertical direction at the left rear of the engine unit 10.

  In the engine unit 10 according to the present embodiment, the first breather chamber 116 and the second breather chamber 117 are provided in front of the crankcase 110. Therefore, the breather wall BW (the right breather wall RW2 and the left breather wall LW2, see FIG. 7) that partitions the first breather chamber 116 and the second breather chamber 117 is exposed between the right lower frame 24R and the left lower frame 24L. is doing.

  Thus, the breather wall BW, which is the outer wall of the first breather chamber 116 and the second breather chamber 117, is exposed between the right lower frame 24R and the left lower frame 24L, so that the right lower frame 24R and the left lower frame 24L are exposed. The first breather chamber 116 and the second breather chamber 117 can be cooled by the air flowing between the frames 24L. Further, the balancer shaft 180 accommodated in the first breather chamber 116 can be cooled. Thereby, a higher gas-liquid separation effect can be obtained.

  As described above, according to the gas-liquid separation structure of the engine according to the present invention, since the gas-liquid separation of the gas-liquid mixture flowing into the passage in the balancer shaft is promoted using the rotational motion of the balancer shaft, Even if it exists, high gas-liquid separation performance can be obtained.

  In addition, this invention is not limited to description of the said embodiment, It can change suitably and implement, without deviating from the scope of the present invention. For example, in the above embodiment, the substantially straight passages are provided as the first passage D1 and the second passage D2, but specific aspects such as the shape of the passage and the width of the passage are not particularly limited. In the above embodiment, the gas discharged from the discharge port 118 (discharge pipe 119) is guided to the intake port 131. However, the gas discharged from the discharge port 118 (discharge pipe 119) is the atmosphere. It may be configured to be released. Further, the number and arrangement of the holes H1, H2, and H3 can be appropriately changed within a range in which the gas-liquid separation structure of the engine can be appropriately realized.

  The gas-liquid separation structure of an engine according to the present invention is useful for an engine of a motorcycle, for example.

DESCRIPTION OF SYMBOLS 1 Motorcycle 2 Body frame 3 Front wheel 4 Rear wheel 5 Radiator 6 Air cleaner box 7 Fuel tank 8 Seat 10 Engine unit 110 Crankcase 110R Right crankcase 110L Left crankcase 111 Crank chamber 112 Crankshaft 113 Oil storage chamber 113a Lead valve 114 Oil Passage 115 Transmission chamber 116 First breather chamber 116a Right bearing portion 116b Left bearing portion 117 Second breather chamber 118 Discharge port 119 Discharge pipe 120 Cylinder 121 Piston 122 Connecting rod (connecting rod)
123 Combustion chamber 130 Cylinder head 131 Intake port 132 Exhaust port 133 Intake valve 134 Exhaust valve 140 Head cover 150 Magnet cover 151 Magnet chamber 152 Oil pump 160 Clutch cover 161 Clutch chamber 162 Gear 170 Intake pipe 180 Balancer shaft 181 Shaft 181a Cap plug)
182 Weight part 183 Balancer gear W1, W2 Wall LW1 Magnet wall LW2 Left breather wall LW3 Left partition wall RW1 Clutch wall RW2 Right breather wall RW3 Right partition wall BW Breather wall PW Partition wall D1 First passage D2, Second passage H1, Second passage H1 H3 hole

Claims (5)

A crankshaft rotatably supported in a crank chamber provided in the crankcase, and a balancer shaft configured to rotate according to the rotation of the crankshaft,
The balancer shaft has a shaft portion serving as a rotation shaft, and a weight portion extending radially outward of the shaft portion on one end side of the shaft portion,
A first passage is provided in the shaft portion, and a second passage communicating with the first passage is provided in the weight portion,
The first passage communicates with the outside of the balancer shaft through a hole provided in the shaft portion, and the second passage communicates with the outside of the balancer shaft through a hole provided in the weight portion,
The gas-liquid mixture flowing into the second passage from the hole provided in the weight portion is separated into liquid and gas by the rotation of the balancer shaft, and the separated gas passes through the first passage and the hole in the shaft portion. The gas-liquid separation structure of an engine, wherein the structure is discharged from the balancer shaft to the outside.   The gas-liquid separation structure for an engine according to claim 1, wherein the balancer shaft is disposed above the crankshaft. A breather chamber configured to include a first breather chamber in which the shaft portion of the balancer shaft is accommodated, and a second breather chamber above the first breather chamber;
The first breather chamber and the second breather chamber communicate with each other through a hole provided in a wall separating them, and the second breather chamber communicates with the outside through a discharge port,
3. The engine according to claim 2, wherein the gas released to the outside of the balancer shaft is discharged from the exhaust port through the first breather chamber and the second breather chamber. Gas-liquid separation structure.   The engine gas-liquid separation structure according to claim 3, wherein the gas discharged from the exhaust port is guided to an intake port.   When the breather chamber is disposed in front of the crank chamber, the outer wall of the breather chamber is exposed between the left and right lower frames in a motorcycle in which the down tube of the main frame branches downward to the left and right lower frames. The gas-liquid separation structure for an engine according to claim 4, wherein the structure is configured as described above.

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