JP4335342B2 - Crankcase ventilation passage - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a crankcase ventilation passage provided in an engine including a sprocket at least partially immersed in oil in an oil pan.
[0002]
[Prior art]
In the engine crankcase, a crankcase ventilation passage is generally opened to recirculate the blow-by gas that has passed between the piston and cylinder to the intake system and suppress pressure pulsation caused by the reciprocating motion of the piston. (See JP-A-61-135914).
[0003]
On the other hand, an engine in which an oil pump driven by a chain / sprocket mechanism is provided below the crankshaft and a chain tensioner and a chain guide are provided on an end wall in the crankshaft direction of the cylinder block is disclosed in Japanese Patent Application Laid-Open No. 62-233423. It is disclosed in the publication. In such an engine in which the drive sprocket of the oil pump is submerged below the oil level, the oil is scraped up by the rotating sprocket, and the oil adhering to the chain is scattered in the crankcase.
[0004]
The oil scattering in the crankcase as described above is not preferable because the oil content mixed in the blow-by gas increases, adversely affects the exhaust gas treatment and leads to an increase in oil consumption.
[0005]
[Problems to be solved by the invention]
To avoid the above disadvantages, it is necessary to install a shielding plate for the opening of the blow-by gas passage and a large oil separation chamber. However, if these measures are taken, the number of parts will increase and the engine structure will become complicated and large. Will be invited.
[0006]
The present invention has been devised in order to solve such problems of the prior art, and its main purpose is to increase the number of parts and increase the complexity and size of the engine structure. It is an object of the present invention to provide a crankcase ventilation passage capable of suppressing oil contamination in the body.
[0007]
[Means for Solving the Problems]
To achieve the above objects, the present onset Ming, a crankcase ventilation passageway at least partially into the oil in the oil pan 3 is provided in the engine E provided with a sprocket 18 Tsu-zuke, the blow-by gas A blow-by gas chamber 25 formed in the engine body (lower block 2 and oil pan 3), a space for accommodating the sprocket, and the blow-by gas chamber for recirculating to the intake system and separating oil in the blow- by gas An end wall in the crankshaft direction of the engine body separating the engine body, a first hole (small hole 37) provided in the end wall for communicating the blow-by gas chamber and the outside of the end wall, and the end wall A second hole (hole 38) provided to communicate the inside of the crankcase and the outside of the end wall; and an outside of the end wall. The tensioner of the chain 19 wound around the sprocket, which is isolated from the space for housing the sprocket and defines a gap G between the end wall and the first hole and the second hole. 21 or a support base 23a of the guide 23. If it does in this way, the penetration | invasion prevention of the oil to the blow-by gas chamber for isolate | separating an oil component can be achieved without requiring a special member. In particular, if at least a part of the passage to the blow-by gas chamber is formed by the support base, the crankcase ventilation passage can be easily formed by effectively utilizing the support base of the tensioner and the guide.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to an embodiment shown in the accompanying drawings.
[0009]
FIG. 1 is an elevation view on the crank pulley side of a four-cycle V-type 8-cylinder engine to which the present invention is applied.
[0010]
The engine E includes a V-shaped upper block 1 in which the narrow angle of the cylinder axis is set to 90 degrees, a lower block 2 joined to the lower surface of the upper block 1, and an oil joined to the lower surface of the lower block 2. It consists of a pan 3 and a cylinder head 4 joined to the upper surfaces of both cylinders of the upper block 1. Two camshafts 5 are provided above each cylinder head 4. These cam shafts 5 are covered with a head cover 6 joined to the upper surface of the cylinder head 4. A crankshaft 7 is supported by a main bearing on the joint surface between the upper block 1 and the lower block 2.
[0011]
A compressor 8 of an air conditioner is attached to one side (right side in FIG. 1) of the crankshaft 7 in the upper block 1, and the other side of the crankshaft 7 in the lower block 2 (see FIG. 1). An AC generator 9 is attached to the left side). The compressor 8 and the AC generator 9 are linked to the crankshaft 7 via a belt / pulley mechanism (not shown).
[0012]
A crank sprocket 10 is fitted on the crankshaft 7 at an axially inner position of the crank pulley, and a drive pinion 11 is fitted further on the axially inner side thereof.
[0013]
The drive pinion 11 is simultaneously meshed with two driven pinions 12 provided at symmetrical positions with respect to a vertical plane that bisects the narrow angle of the cylinder axis and passes through the center of the crankshaft. Each of these two driven pinions 12 is integrally provided with a small sprocket 13, and the small sprocket 13 and the cam sprocket 14 provided on each of the two camshafts 5 on both cylinder heads 4. Between them, the camshaft driving silent chain 15 is wound. Thereby, the rotational force of the crankshaft 7 is transmitted to each of the two camshafts 5 on both cylinder heads 4.
[0014]
The upper block 1 and the lower block 2 are divided from a horizontal plane through which the center of the crankshaft passes, and two balance shafts 16a in which the axes extend parallel to the axis of the crankshaft 7 at symmetrical positions with respect to the divided surface.・ 16b is pivotally supported.
[0015]
Of these two balance shafts, a balance shaft sprocket 17 is fitted to the shaft end of the one 16b supported on the lower block 2 side. A silent chain 19 is wound around the balance shaft sprocket 17, the crank sprocket 10, and a pump sprocket 18 fixed to an oil pump (not shown) attached to the lower surface of the lower block 2. The balance shaft 16b and the oil pump rotate in conjunction with the crankshaft 7.
[0016]
The two balance shafts 16a and 16b are rotated in the opposite directions at the same rotational speed by the meshing of the gears 20a and 20b having the same number of teeth fitted inside the balance shaft sprocket 17 in the axial direction. It has become. As a result, the horizontal component of the vibration generating force due to the piston movement on the cylinder shaft arranged in a V shape is canceled out.
[0017]
Each of the silent chain 15 wound around the cam sprocket 14 of each camshaft 5 and the silent chain 19 wound around the balance shaft sprocket 17 and the pump sprocket 18 is a chain whose pressing force is automatically adjusted by a hydraulic plunger 21. A tensioner 22 and a chain guide 23 for steadying are attached. The chain tensioner 22 and the chain guide 23 are fixed at appropriate positions on the end faces of the upper block 1, the lower block 2, the oil pan 3, and the cylinder head 4 on the crank pulley side using bolts or the like. The end face of the engine E on the crank pulley side is almost entirely covered with a chain cover (not shown).
[0018]
As shown in FIGS. 2 and 3, the oil content in the blow-by gas that circulates from the crankcase 24 to the intake system is removed between the joint surfaces of the lower block 2 and the oil pan 3 on the left and right sides in FIG. A blow-by gas chamber 25 is formed on the right side, and a fresh air chamber 26 is formed on the left side to guide outside air taken in from the intake system into the crankcase 24.
[0019]
Both chambers 25 and 26 are open at both end walls in the crankshaft direction of the lower block 2, but have a large cross-sectional area compared to the opening area, and air flow lines parallel to the crankshaft 7. The inside of the ribs 27 is formed in a maze shape by a plurality of ribs 27 protruding alternately in a direction orthogonal to the direction. These ribs 27 not only improve the oil separation function by making the passage a labyrinth, but also help to suppress a reduction in rigidity due to the formation of a large volume cavity.
[0020]
The upper walls of the chambers 25 and 26 have counterweights 28 whose inner peripheral contours are integral with the crankshaft 7 so as to partition between the crankcase 24 formed in the upper and lower blocks 1 and 2 and the oil pan 3. Is defined by a baffle 29 corresponding to the rotation trajectory. The blow-by gas chamber 25 is provided at a position partially overlapping the balance shaft housing chamber 30 formed on the left side of the crankcase 24 when viewed from the side. By doing so, the dead space can be effectively utilized, so that an oil separation chamber having a relatively large volume can be formed without increasing the size of the entire engine.
[0021]
In addition, since fresh outside air passes through the fresh air chamber 26 side, there is usually no oil mixing, but this side is also formed as a maze in consideration of the backflow of blow-by gas.
[0022]
In the connecting portion of the baffle 29 with respect to the inner surface of the left side wall of the lower block 2 in FIG. Further, the balance shaft accommodating chamber 30 is opened to a left oil passage 32 formed on a joint surface between the lower block 2 and the oil pan 3 through a vertical passage 33 appropriately opened at the bottom thereof. Since the oil passages (vertical passage 33 and left oil passage 32) communicating with the oil pan 3 below the balance shaft housing chamber 30 communicate with each other, the lubricating oil flowing out from the bearing portions of the balance shafts 16a and 16b is The oil pan 3 can be quickly returned.
[0023]
3 at a suitable position of the connecting portion of the baffle 29 with respect to the inner surface of the right side wall of the lower block 2 in FIG. 3 toward the right oil passage 34 formed at the joint surface between the lower block 2 and the oil pan 3. A hole 35 is opened.
[0024]
The oil in the crankcase wound up by the rotation of the counterweight 28 of the crankshaft 7 quickly returns to the oil pan 3 through the passages 31, 33, 35 and the flow paths 32, 34. Although the bottom surface is shielded by the baffle plate 36, the oil return does not deteriorate.
[0025]
As shown in FIGS. 4 and 5, the opening of the blow-by gas chamber 25 in the end wall on the crank pulley side is composed of a plurality of small holes 37 provided in the end wall of the lower block 2. The oil is communicated with the space above the oil level in the oil pan 3 through the provided hole 38. The portion provided with the small hole 37 and the hole 38 is surrounded by a rib 39 and a chain provided between the balance shaft sprocket 17 and the pump sprocket 18 so as to abut against the edge of the rib 39. The front surface of the guide 23 is closed by the support base 23a. In other words, the small hole 37 is opened at a position shielded by the support base 23a of the chain guide 23. As a result, it is possible to prevent the oil from entering the blow-by gas chamber 25 for separating the oil without requiring a special member.
[0026]
The blow-by gas containing oil mist flows into the blow-by gas chamber 25 through the small hole 37 from the gap G between the inner surface of the support base 23a of the chain guide 23 and the front surface of the lower block 2 (see the arrow in FIG. 5). The oil component is also separated when passing through the gap G and the small hole 37. Here, a part of the passage to the blow-by gas chamber 25 is formed by the support base 23a. In this case, the crankcase ventilation passage is made effective by effectively using the support base such as a chain guide. It can be formed easily.
[0027]
The chain guide 23 is fixed to the lower block 2 and the oil pan 3 by first and second fastening portions F1 and F2, respectively. Further, the support base 23a also has a third fastening portion F3. Therefore, the support rigidity of the chain guide 23 is further enhanced.
[0028]
On the other hand, a rib 40 is provided around the opening of the fresh air chamber 26 on the crank pulley side end wall in the same manner as described above, but this side is provided with a rib provided on the inner surface of the chain cover (not shown). In cooperation with each other, a passage is defined between the hole 41 in the end wall of the lower block 2 and the hole 42 in the end wall of the oil pan 3. A notch 43 is provided in a part of the rib 40 so that fresh air can be introduced into the entire chain cover.
[0029]
By taking such measures, the opening of the blow-by gas chamber 25 is blocked by the support base 23a of the chain guide 23, so that the oil that has been scraped up by the rotation of the pump sprocket 18 and scattered in the crankcase 24 is blow-by gas chamber. Intrusion into 25 can be suppressed. The fresh air chamber 26 does not need to be completely blocked because the amount of oil scattered is relatively small due to the rotational direction of the pump sprocket 18, but the hole 41 on this side is also blocked by the support base of the tensioner 22. May be.
[0030]
As shown in FIG. 6, the end wall on the other end side of the blow-by gas chamber 25 and the hole on the other end side of the fresh air chamber 26 are formed on the end wall of the upper and lower blocks 1 and 2 on the joint surface side with the transmission. 45 is open. A pair of blow-by gas passages 46 formed along the axis of the crankshaft 7 at the bottom of the valley between the banks B in the upper block 1, a fresh air passage 47, and other chambers 25 and 26. Recesses 48 and 49 for connecting between the end holes 44 and 45 are recessed in the end wall. By joining the end plate 50 to the vertical plane V around these recesses 48 and 49, connection passages 51 and 52 are formed which communicate with the blow-by gas chamber 25 and the fresh air chamber 26 independently of each other. (See Figs. 7 and 8). Although not shown in the figure, like the blow-by gas chamber 25 and the fresh air chamber 26, ribs in the direction orthogonal to the air flow lines are alternately projected to make the inside a labyrinth. These passages 51 and 52 can also be provided with an oil separation function.
[0031]
Between the banks B, as shown in FIG. 9, an intake manifold body 53 is arranged at a symmetrical position with respect to the center of the bank narrow angle. The intake manifold body 53 includes an intake chamber 56 that is formed in the lower center of a surge tank 55 including a pair of throttle bodies 54 and that is long in the crankshaft direction (the intake pipe from the intake chamber 56 to the intake port of each cylinder) And is joined on a horizontal plane H formed inside the banks of both cylinder heads 4. In the cylinder head 4, a blow-by gas passage 46 provided in the upper block 1 and passages 57 and 58 connected to the openings of the portions 46 a and 47 a along the cylinder axis of the new air passage 47 are also provided. The passages 59 and 60 are respectively formed in the passages 57 and 58, and at the same time as fresh air is introduced from the throttle valve upstream 54a of the throttle body 54, blow-by gas is sent to the throttle valve downstream 54b of the throttle body 54. Is designed to recirculate. Since the PCV valve 61 is embedded in the opening on the intake manifold body 53 side of the blow-by gas passage 57 of the cylinder head 4, there is no possibility of dropping off.
[0032]
The blow-by gas from the blow-by gas chamber 25 is distributed to the intake systems of the two banks B through the passages described above, and fresh air from the intake systems of the two banks B merges and flows into the fresh air chamber 26. It is supposed to be. A fresh air passage 47 drilled in the crankshaft direction at the bottom of the valley between the banks B in the upper block 1 is not shown through a passage 47b drilled along the cylinder shaft. The valve chamber is also communicated, and the oil staying in the valve chamber is prevented from deteriorating due to contact with the blow-by gas by ventilating the valve chamber.
[0033]
【The invention's effect】
As described in detail above, according to the first aspect of the present invention, oil can be prevented from entering the blow-by gas chamber without requiring a special member. According to the second aspect of the present invention, the crankcase ventilation passage can be easily formed by effectively utilizing the support base of the tensioner and the guide. Therefore, according to the present invention, a great effect can be obtained in suppressing the mixing of oil into the blow-by gas without increasing the number of parts or complicating or increasing the size of the engine structure.
[Brief description of the drawings]
FIG. 1 is an elevation view of a crank pulley side of a V-type engine to which the present invention is applied. FIG. 2 is a bottom view showing an oil pan connecting surface of a lower block of the engine shown in FIG. Sectional view taken along line III-III in FIG. 4 [FIG. 4] Partial elevational view of the end face on the crank pulley side of the engine shown in FIG. 6 is a partial elevational view of the transmission-side end face of the engine shown in FIG. 1. FIG. 7 is a cross-sectional view of the main part along the line VII-VII in FIG. 6. FIG. Fig. 9 is a cross-sectional view of the main part taken along line VIII. Fig. 9 is a cross-sectional view of the main part of the part including the intake system of the engine shown in Fig. 1. Fig. 10 is a top view of the upper block of the engine shown in Fig. 1.
E Engine 2 Cylinder block 3 Oil pan 18 Sprocket 19 Chain 21 Tensioner 23 Guide 23a Support base 24 Crankcase 25 Blow-by gas chamber 37 Hole

Claims (3)

A crankcase ventilation passage provided in an engine provided with a sprocket at least partially immersed in oil in an oil pan,
A blow- by gas chamber formed in the engine body to recirculate the blow-by gas to the intake system and separate the oil in the blow-by gas;
An end wall in the crankshaft direction of the engine body that separates the space for housing the sprocket and the blow-by gas chamber;
A first hole provided in the end wall for communicating the blow-by gas chamber with the outside of the end wall;
A second hole provided in the end wall for communicating the inside of the crankcase with the outside of the end wall;
Outside the end wall, it is wound around the sprocket, which is isolated from the space for housing the sprocket and defines a gap between the end wall and the first hole and the second hole. Chain tensioner or guide support base
Crankcase ventilation passage, characterized in that it comprises a. The end wall is provided with a rib projecting around the part where both the holes are open,
  The crankcase ventilation passage according to claim 1, wherein the gap is defined by the support base, the rib, and the end wall.   The crankcase ventilation passage according to claim 1 or 2, wherein at least a part of the passage to the blow-by gas chamber is formed by the support base.

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