Breather Device

Abstract

To suppress leakage of oil from an air cleaner by improving air-liquid separation performance for blowby gas.SOLUTION: A cylinder axial line of an engine (30) is inclined frontward close to horizontal, and a breather device (50) for returning blowby gas into an air cleaner (41) located in an upper part of a crankcase (31) from a cylinder head cover (34) is arranged at the engine. The breather device is provided with a breather chamber (51) which is formed at the cylinder head cover, a first breather hose (53) extending rearward from the breather chamber, a branch part (55) connected to a rear end part of the first breather hose, a second breather hose (54) extending upward toward the air cleaner from the branch, and an oil return hose (56) extending downward toward the crankcase from the branch part.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a breather device for an engine. [Background technology]

[0002] The engine of a straddle-type vehicle is provided with a breather device that returns blow-by gas generated from the crankcase or the like to the air cleaner for re-burning. One such breather device known in the art is one in which a breather chamber is formed in the cylinder head cover (see, for example, Patent Document 1). In the breather device described in Patent Document 1, the breather chamber in the cylinder head cover is connected to the air cleaner through a breather hose. Oil mist in the blow-by gas is captured in the breather chamber, and the blow-by gas that passes through the breather chamber is returned to the upstream side of the intake passage through the breather hose. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4670996 Summary of the Invention [Problem to be solved by the invention]

[0004] The engine described in Patent Document 1 has a small difference in height between the breather chamber and the air cleaner, which means that oil mist contained in the blow-by gas can easily reach the air cleaner, and there is a risk of oil leaking from the mating surfaces of the air cleaner, etc.

[0005] The present invention has been made in view of the above points, and has as its object to provide a breather device that can improve the gas-liquid separation performance of blow-by gas and suppress oil leakage from the air cleaner. [Means for solving the problem]

[0006] A breather device according to one aspect of the present invention comprises: The engine mounted on the saddle-type vehicleThe cylinder axis is tilted forward and close to horizontal, and the breather device returns blow-by gas from the cylinder head cover to an air cleaner above the crankcase, and the breather chamber is formed in the cylinder head cover, and the rear of the breather chamber is Diagonally downward a first breather hose extending from the rear end of the first breather hose; a branched portion connected to a rear end of the first breather hose; a second breather hose extending upward from the branched portion toward the air cleaner; and an oil return hose extending downward from the branched portion toward the crankcase. a cylinder head and a cylinder are interposed between the cylinder head cover and the crankcase, the branch portion overlaps the cylinder in a side view of the vehicle, and the branch portion is closer to a mating surface of the cylinder and the crankcase than to a mating surface of the cylinder and the cylinder head; This solves the above problem. [Effects of the Invention]

[0007] According to one aspect of the breather device of the present invention, the breather passage extending from the breather chamber toward the rear is branched into upper and lower sections along the way by the first and second breather hoses and the oil return hose. This makes it difficult for oil mist in the blow-by gas to flow toward the air cleaner through the second breather hose. Furthermore, oil liquefied in the first and second breather hoses is returned to the crankcase through the oil return hose. Therefore, even if the difference in elevation between the breather chamber and the air cleaner is small, the gas-liquid separation performance of the blow-by gas can be improved, and oil leakage from the air cleaner can be suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a left side view of a saddle-ride type vehicle according to an embodiment of the present invention; [Figure 2] FIG. 1 is a perspective view of an engine according to an embodiment of the present invention. [Figure 3] FIG. 2 is a side view of the engine of the present embodiment. [Figure 4] FIG. 2 is a front view of the engine of the present embodiment. [Figure 5] FIG. 5 is a cross-sectional view of the engine of FIG. 4 taken along line AA. DETAILED DESCRIPTION OF THE INVENTION

[0009] In one embodiment of the present invention, the engine has a cylinder axis tilted forward and close to horizontal. The engine is provided with a breather device that returns blow-by gas from the cylinder head cover to an air cleaner above the crankcase. A breather chamber of the breather device is formed in the cylinder head cover, and a first breather hose extends rearward from the breather chamber. A branch is connected to the rear end of the first breather hose, and a second breather hose extends upward from the branch toward the air cleaner, and an oil return hose extends downward from the branch toward the crankcase. The first and second breather hoses and the oil return hose branch the breather passage extending rearward from the breather chamber into upper and lower parts along the way. This makes it difficult for oil mist in the blow-by gas to flow toward the air cleaner through the second breather hose. In addition, oil liquefied in the first and second breather hoses is returned to the crankcase through the oil return hose. Therefore, even if the difference in height between the breather chamber and the air cleaner is small, the gas-liquid separation performance of blow-by gas can be improved and oil leakage from the air cleaner can be suppressed. [Example]

[0010] A saddle-ride type vehicle to which the breather device of this embodiment is applied will be described below with reference to the accompanying drawings. Fig. 1 is a left side view of the saddle-ride type vehicle of this embodiment. In the following drawings, arrow FR indicates the front of the vehicle, arrow RE indicates the rear of the vehicle, arrow L indicates the left side of the vehicle, and arrow R indicates the right side of the vehicle.

[0011] As shown in Figure 1, a scooter-type saddle-ride vehicle 1 is configured by attaching various covers to an underbone-type body frame (not shown) as the exterior of the body. A front frame cover 11 is provided at the front of the vehicle, and a front leg shield 12 that protects the rider's legs is provided behind the front frame cover 11. A footboard 13 extends rearward from the lower end of the front leg shield 12, and a seat frame cover 14 is provided behind the footboard 13. The front leg shield 12 and footboard 13 form a space in front of a main seat 15 for the rider's feet.

[0012] A handlebar 21 is provided above the front frame cover 11, and a front wheel 23 is rotatably supported below the front frame cover 11 via a pair of front forks 22. A main seat 15 and a sub-seat 16 are provided above the seat frame cover 14, and a unit swing-type engine 30 is provided below the seat frame cover 14. The engine 30 is swingably connected to the body frame, and a rear wheel 24 is rotatably supported at the rear of the engine 30. A CVT cover 37 covers the left side of a crankcase 31 of the engine 30, and an air cleaner 41 is provided above the CVT cover 37.

[0013] Blow-by gas is generated in the engine 30, and when the internal pressure of the engine 30 increases due to the blow-by gas, resistance to the pistons and other components increases, causing mechanical loss and damage to seals. For this reason, it is necessary to return the blow-by gas from the engine 30 to the air cleaner 41. The blow-by gas contains not only combustion gases but also oil mist and the like. To prevent the oil mist from reaching the air cleaner 41, it is desirable to separate gas and liquid in the breather chamber of the engine 30. It is also desirable to provide a difference in elevation between the breather chamber and the air cleaner 41 so that the oil separated from the blow-by gas returns to the engine 30 under its own weight.

[0014] Generally, scooter-type saddle-ride vehicles have a low seat height and often have the engine cylinder axis oriented approximately horizontally. Furthermore, in scooter-type saddle-ride vehicles, the helmet box is located below the seat, and layout restrictions make it difficult to create a difference in height between the engine and the air cleaner. This means that oil mist that has not separated from the blow-by gas in the breather chamber can easily get into the air cleaner, causing oil to drip onto the clean side of the air cleaner. In the worst case scenario, this could result in an oil leak from the mating surface of the air cleaner.

[0015] Furthermore, if the difference in elevation between the engine and the air cleaner is small, oil does not return completely from the air cleaner to the engine even when the engine is stopped. Therefore, when the engine is restarted, oil that has remained near the air cleaner is likely to enter the air cleaner in a short period of time. Therefore, in this embodiment, the hose extending rearward from the breather chamber of the engine 30 branches into upper and lower parts along the way and is connected to the air cleaner 41 and the crankcase 31. This promotes gas-liquid separation of the blow-by gas, making it difficult for oil mist to enter the air cleaner 41, and making it easier for the liquefied oil to return to the crankcase 31.

[0016] The engine will now be described with reference to Fig. 2. Fig. 2 is a perspective view of the engine of this embodiment.

[0017] As shown in Figure 2, a cylinder assembly is disposed in front of a crankcase 31 of an engine 30. The cylinder assembly includes a cylinder 32 (see Figure 3) attached to the front of the crankcase 31, a cylinder head 33 (see Figure 3) attached to the front of the cylinder 32, and a cylinder head cover 34 attached to the front of the cylinder head 33. In this way, the cylinder assembly protrudes forward from the crankcase 31, and the cylinder axis is tilted forward and close to horizontal. The cylinder 32 and cylinder head 33 are covered by an engine cover 35.

[0018] The crankcase 31 has a left-right split structure consisting of left and right case halves 36L, 36R, with the left case half 36L extending further rearward than the right case half 36R. A CVT cover 37 is attached to the open left side surface of the left case half 36L, and a belt-type continuously variable transmission (not shown) is housed inside the CVT cover 37. A magneto cover 38 (see FIG. 4) is attached to the open right side surface of the right case half 36R, and a magneto (not shown) is housed inside the magneto cover 38. An air cleaner 41 is disposed above the left case half 36L and the CVT cover 37.

[0019] An intake pipe 42 is attached to the upper surface of the cylinder head 33 and curves rearward. The downstream end of a throttle body 43 is connected to the intake pipe 42, and a connecting tube 44 is connected to the upstream end of the throttle body 43. The connecting tube 44 extends rearward from the throttle body 43 and is connected to the right side of the air cleaner 41. An exhaust pipe 45 is attached to the lower surface of the cylinder head 33 and curves to the right before extending rearward. A catalyst 46 (see Figure 4) is provided midway through the exhaust pipe 45, and a muffler 47 is connected to the rear end of the exhaust pipe 45.

[0020] A breather chamber 51 is formed inside the cylinder head cover 34, and the breather chamber 51 separates the blow-by gas generated inside the crankcase 31 into gas and liquid. A nipple 52 is provided on the outer wall of the breather chamber 51, and a front end of a first breather hose 53 is connected to the nipple 52. The first breather hose 53 extends rearward from the breather chamber 51, and a branch portion 55 is connected to the rear end of the first breather hose 53. The branch portion 55 is a T-shaped three-way pipe, and the branch pipe connected to the first breather hose 53 faces forward, and the remaining two branch pipes face upward and downward (see FIG. 5 in particular).

[0021] A second breather hose 54 is connected to the branch pipe above the branch portion 55. The second breather hose 54 extends upward from the branch portion 55, and the upper end of the second breather hose 54 is connected to the air cleaner 41. An oil return hose 56 is connected to the branch pipe below the branch portion 55. The oil return hose 56 extends downward from the branch portion 55, and the lower end of the oil return hose 56 is connected to a nipple 57 of the crankcase 31. As will be described in detail later, the nipple 57 is connected to an oil return passage 58 (see FIG. 5) of the crankcase 31, and the oil return passage 58 is connected to an oil reservoir.

[0022] In this way, the engine 30 is formed with a breather device 50 that returns blow-by gas from the cylinder head cover 34 to the air cleaner 41 via the breather chamber 51, the first breather hose 53, the second breather hose 54, the oil return hose 56, and the branching portion 55. The blow-by gas is sent from the breather chamber 51 to the air cleaner 41 through the first breather hose 53 and the second breather hose 54. When the oil in the blow-by gas liquefies while traveling from the breather chamber 51 to the air cleaner 41, the oil is returned to the oil reservoir in the crankcase 31 through the oil return hose 53 due to its own weight.

[0023] The detailed configuration of the breather device will be described below with reference to Figures 3 to 5. Figure 3 is a side view of the engine of this embodiment. Figure 4 is a front view of the engine of this embodiment. Figure 5 is a cross-sectional view of the engine of Figure 4 taken along line AA. For ease of explanation, the engine cover is omitted from Figure 3.

[0024] As shown in Figure 3, on the left side of the engine 30, the breather chamber 51, the air cleaner 41, and the crankcase 31 are connected via a first breather hose 53, a second breather hose 54, and an oil return hose 56. The first breather hose 53, the second breather hose 54, and the oil return hose 56 are connected at a branch point 55. The branch point 55 is located below the nipple 52 on the top of the cylinder head cover 34, i.e., below the front end of the first breather hose 53. This increases the difference in height between the branch point 55 and the air cleaner 41, making it difficult for oil mist in the blow-by gas to flow toward the air cleaner 41.

[0025] In a side view of the vehicle, the branch portion 55 overlaps the cylinder 32, and is closer to a mating surface 62 between the cylinder 32 and the crankcase 31 than to a mating surface 61 between the cylinder 32 and the cylinder head 33. At this time, the first breather hose 53 extends obliquely downward from the breather chamber 51 toward the branch portion 55 at the rear, and the second breather hose 54 extends upward from the branch portion 55 toward the air cleaner 41. More specifically, the first breather hose 53 extends to the branch portion 55 so as to overlap the cylinder assembly, and the second breather hose 54 extends above the cylinder 32 and then extends rearward to the air cleaner 41.

[0026] The first and second breather hoses 53, 54 lengthen the breather passage from the breather chamber 51 to the air cleaner 41, which cools the blow-by gas in the breather passage, promoting gas-liquid separation and making it difficult for oil mist to head toward the air cleaner 41. In particular, the first breather hose 53 extends from the breather chamber 51 to near the mating surface 62 of the crankcase 31, making the first breather hose 53 longer and promoting gas-liquid separation. In addition, because the breather passages within the branching portion 55 are perpendicular to each other, when oil mist flows from the first breather hose 53 into the branching portion 55, the oil mist collides with the inner surface of the branching portion 55, promoting gas-liquid separation.

[0027] Because the first breather hose 53 is inclined diagonally downward and rearward, oil liquefied in the first breather hose 53 flows into the oil return hose 56. Because the second breather hose 54 extends vertically, oil liquefied in the second breather hose 54 flows into the oil return hose 56. For this reason, oil liquefied in the first and second breather hoses 53, 54 easily returns to the crankcase 31 through the oil return hose 56. In addition, in this embodiment, to promote gas-liquid separation, the first breather hose 53 is the longest, the second breather hose 54 is the second longest, and the oil return hose 56 is the shortest.

[0028] As shown in Figure 4, in a front view of the vehicle, the branch portion 55 is located on the left side of the engine cover 35 (cylinder 32) and inward in the vehicle width direction from a mating surface 63 between the crankcase 31 and the CVT cover 37. The exhaust pipe 45 extends from the underside of the engine cover 35 (cylinder head 33) and passes to the right side of the engine cover 35. For this reason, the branch portion 55 is located on the opposite side of the engine cover 35 (cylinder 32) from the exhaust pipe 45, which is a heat source. Heat damage to the branch portion 55 is suppressed, and an increase in the oil temperature of the oil and oil mist that collects at the branch portion 55 is suppressed, thereby improving the gas-liquid separation performance in the breather passage.

[0029] As shown in Figure 5, the oil return hose 56 is connected to an oil return passage 58 in the crankcase 31 via a nipple 57. The outlet of the oil return passage 58 is located below an oil level 65 in the oil reservoir in the crankcase 31. The oil that has liquefied in the first and second breather hoses 53, 54 is returned to a position below the oil level 65 in the oil reservoir through the oil return hose 56 and the oil return passage 58. Pressure pulsations occur in the crankcase 31 due to the reciprocating movement of the pistons, etc., but the effect of the pressure pulsations on the breather passage is suppressed, preventing oil from spraying out from the crankcase 31 into the air cleaner 41.

[0030] As described above, according to the breather device 50 of this embodiment, the breather passage leading from the breather chamber 51 to the rear is branched into upper and lower parts along the way by the first and second breather hoses 53, 54 and the oil return hose 56. This makes it difficult for oil mist in the blow-by gas to flow toward the air cleaner 41 through the second breather hose 54. Furthermore, oil liquefied in the first and second breather hoses 53, 54 is returned to the crankcase 31 through the oil return hose 56. Therefore, even if the difference in elevation between the breather chamber 51 and the air cleaner 41 is small, the gas-liquid separation performance of the blow-by gas can be improved and oil leakage from the air cleaner 41 can be suppressed.

[0031] The branch section may be provided with a volume to vary the flow rate of the blow-by gas and promote gas-liquid separation. In this case, a cavity of sufficient size is provided in the branch section to improve gas-liquid separation performance.

[0032] In addition, the first breather hose, the second breather hose, and the oil return hose may have different inner diameters to promote gas-liquid separation. For example, the inner diameter of the oil return hose may be smaller than the inner diameter of the first breather hose. Also, a throttle may be provided at the branching section.

[0033] In this embodiment, the first breather hose extends diagonally downward from the breather chamber toward the rear, but the first breather hose may extend toward the rear. For example, the first breather hose may extend horizontally toward the rear.

[0034] Furthermore, in this embodiment, the branched portion is disposed below the front end of the first breather hose, but it is sufficient that the branched portion is disposed so as to have a difference in height from the air cleaner.

[0035] In addition, although the branching portion is branched in a T-shape in this embodiment, the branching portion may be branched in three directions. For example, the branching portion may be branched in a Y-shape.

[0036] Furthermore, in this embodiment, the branching portion is disposed on the side of the cylinder, but the branching portion may be disposed on the side of the cylinder head or the crankcase.

[0037] In this embodiment, the outlet of the oil return passage in the crankcase is located below the oil level in the oil reservoir, but the outlet of the oil return passage in the crankcase may be located above the oil level in the oil reservoir. In this case, it is preferable to provide a check valve in the oil return passage or the oil return hose.

[0038] Furthermore, the breather device of this embodiment is not limited to the engine of the saddle-ride vehicle described above, and may be used in engines of other vehicles. Furthermore, the saddle-ride vehicle is not limited to a motorcycle, but may be any vehicle equipped with an engine. Note that the saddle-ride vehicle is not limited to all vehicles in which the rider sits astride the seat, as in this embodiment, but also includes scooter-type vehicles in which the rider does not sit astride the seat.

[0039] As described above, the breather device (50) is a breather device in which the cylinder axis is tilted forward and close to horizontal, and which returns blow-by gas from the cylinder head cover (34) to the air cleaner (41) above the crankcase (31). The breather device includes a breather chamber (51) formed in the cylinder head cover, a first breather hose (53) extending rearward from the breather chamber, a branch (55) connected to the rear end of the first breather hose, a second breather hose (54) extending upward from the branch toward the air cleaner, and an oil return hose (56) extending downward from the branch toward the crankcase. With this configuration, the breather passage extending rearward from the breather chamber is branched into upper and lower parts midway by the first and second breather hoses and the oil return hose. This makes it difficult for oil mist in the blow-by gas to flow toward the air cleaner through the second breather hose. Furthermore, oil liquefied in the first and second breather hoses is returned to the crankcase through the oil return hose. Therefore, even if the difference in height between the breather chamber and the air cleaner is small, the gas-liquid separation performance of blow-by gas can be improved and oil leakage from the air cleaner can be suppressed.

[0040] In the breather device, the branching portion is located below the front end of the first breather hose. With this configuration, the difference in height between the branching portion and the air cleaner is large, making it difficult for oil mist in the blow-by gas to flow toward the air cleaner.

[0041] In the breather device, the first breather hose extends diagonally downward toward the rear from the breather chamber, and the second breather hose extends upward from the branching portion. With this configuration, the first and second breather hoses lengthen the breather passage, promoting gas-liquid separation of blow-by gas within the breather passage and making it difficult for oil mist to head toward the air cleaner. In addition, oil liquefied in the first and second breather hoses is more likely to return to the crankcase.

[0042] In the breather device, the cylinder head (33) and the cylinder (32) are interposed between the cylinder head cover and the crankcase, and the branching portion overlaps the cylinder in a side view of the vehicle, and is closer to the mating surface (62) of the cylinder and the crankcase than to the mating surface (61) of the cylinder and the cylinder head. With this configuration, the first breather hose is longer, which promotes gas-liquid separation of the blow-by gas and makes it difficult for oil mist to head toward the air cleaner.

[0043] In the breather device, the oil return hose is connected to an oil return passage (58) in the crankcase, and the outlet of the oil return passage is located below the oil level (65) in the oil reservoir in the crankcase. With this configuration, the oil is returned below the oil level in the oil reservoir, thereby suppressing the effect of pressure pulsations in the crankcase on the breather passage. This prevents oil from spraying from the crankcase to the air cleaner.

[0044] In the breather device, the cylinder head and cylinder are interposed between the cylinder head cover and the crankcase, and the exhaust pipe (45) extends rearward from the underside of the cylinder head, with the branch portion located on one side of the cylinder in the vehicle width direction, and the exhaust pipe passing through the other side of the cylinder in the vehicle width direction. With this configuration, the branch portion is located on the opposite side of the cylinder from the exhaust pipe, which is a heat source. This reduces thermal damage to the branch portion and suppresses an increase in the oil temperature of oil or oil mist that collects at the branch portion, thereby improving gas-liquid separation performance in the breather passage.

[0045] Although the present embodiment has been described, other embodiments may be made by combining the above-described embodiments and modifications in whole or in part.

[0046] Furthermore, the technology of the present invention is not limited to the above-described embodiments, and various changes, substitutions, and modifications may be made without departing from the spirit of the technical idea. Furthermore, if the technical idea can be realized in a different way due to technological advances or other derived technologies, it may be implemented using that method. Therefore, the claims cover all embodiments that may fall within the scope of the technical idea. [Explanation of symbols]

[0047] 30: Engine 31: Crankcase 32: Cylinder 33: Cylinder head 34: Cylinder head cover 41: Air cleaner 45: Exhaust pipe 50: Breather device 51: Breather chamber 53: First breather hose 54: Second breather hose 55: Branch 56: Oil return hose 58: Oil return passage 61: Cylinder and cylinder head mating surface 62: Mating surface between cylinder head and crankcase 65: Oil level

Claims

1. A breather device for returning blow-by gas from a cylinder head cover to an air cleaner above a crankcase when the cylinder axis of an engine mounted on a saddle-ride type vehicle is tilted forward and close to horizontal, a breather chamber formed in the cylinder head cover; a first breather hose extending obliquely downward toward the rear from the breather chamber; a branch portion connected to a rear end portion of the first breather hose; a second breather hose extending upward from the branch portion toward the air cleaner; an oil return hose extending downward from the branch portion toward the crankcase, A cylinder head and a cylinder are interposed between the cylinder head cover and the crankcase, a branch portion overlapping the cylinder in a side view of the vehicle, and the branch portion being closer to a mating surface of the cylinder and the crankcase than to a mating surface of the cylinder and the cylinder head;

2. 2. The breather device according to claim 1, wherein the branched portion is located lower than a front end portion of the first breather hose.

3. 2. The breather device according to claim 1, wherein the oil return hose is connected to an oil return passage in the crankcase, and an outlet of the oil return passage is located below the oil level in the oil reservoir in the crankcase.

4. An exhaust pipe extends rearward from the underside of the cylinder head, 2. The breather device according to claim 1, wherein the branch portion is located on one side of the cylinder in the vehicle width direction, and the exhaust pipe passes through the other side of the cylinder in the vehicle width direction.

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