JP2002242644A - Oil mist reflux mechanism for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely carry out reflux of an oil mist to an oil pan from a mist separator without affecting strength of the oil pan. SOLUTION: A bypass filter 7 for filtering the oil flowing inside a bypass passage 6 for returning a part of the oil to an oil pan 2 is arranged in the middle of the bypass passage 6 which returns a part of the oil forcedly fed from an oil pump 3, and the mist separator 10 and an outlet side of the bypass filter 7 of the bypass passage 6 communicates with each other via an oil mist reflux passage 11. The oil mist separated in the mist separator 10 from a blowby gas is refluxed to the oil pan 2 via the oil mist reflux passage 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil mist recirculation structure for an engine that recirculates oil mist separated from blow-by gas by a mist separator to an oil pan.

[0002]

2. Description of the Related Art In an engine, oil (lubricating oil) is used to lubricate bearings and sliding parts, and a part of this oil is scattered in a crankcase during lubrication to form a mist-like oil mist. And mixes into the blow-by gas leaked from the combustion chamber. Normally, the blow-by gas is returned to the intake pipe again. However, if oil mist is mixed in the intake air, the exhaust performance of the engine is deteriorated. Therefore, in a general engine, the blow-by gas is returned to the intake pipe after separating the blow-by gas and the oil mist using a mist separator.

On the other hand, the oil mist separated from the blow-by gas is returned to the oil pan again. In this case, in the conventional engine, the oil mist return passage is generally provided such that its outlet is located below the oil level of the oil pan. This is because the intake negative pressure acts in the mist separator, so if the outlet of the recirculation passage is set on the oil level of the oil pan, the pressure difference between the inside of the crankcase and the inside of the mist separator causes This is because the oil mist in the return passage flows back to the mist separator together with the blow-by gas.

[0004] The oil mist return passage is usually realized by connecting the oil pan and the mist separator with a dedicated pipe. However, providing dedicated pipes in this way increases the number of pipes and increases the risk of oil leakage,
For example, in Japanese Patent Application Laid-Open No. 2000-87720, an oil level gauge (oil inspection pipe) connected to an oil pan is connected to a mist separator, and an oil mist is returned below the oil level of the oil pan via the oil level gauge. Some techniques have been proposed.

[0005]

However, when a dedicated pipe is directly connected to the oil pan as in the above-described prior art, the strength of the oil pan, which is a thin plate structure, is reduced, and the pipe is not connected to the oil pan. The vibration gives a large load to the oil pan, and oil leakage may occur in the oil pan. Also, when the oil level gauge is used also as the return passage, a load larger than usual may act on the oil pan, so that oil leakage in the oil pan is also concerned.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made in view of the above circumstances. The purpose is to provide a structure.

[0007]

In order to achieve the above object, an oil mist recirculation structure for an engine according to the present invention is characterized in that it is configured as follows. That is,
A bypass filter for filtering the oil flowing through the bypass passage is provided in the middle of the bypass passage that returns a part of the oil pumped from the oil pump to the oil pan, and the oil mist is returned to the mist separator and the outlet side of the bypass filter in the bypass passage. The oil mist separated from the blow-by gas by the mist separator is returned to the oil pan through the oil mist return passage.

Since the bypass filter is a fine-grained filter and the outlet side passage is narrowed, the hydraulic pressure at the outlet side of the bypass filter in the bypass passage becomes substantially equal to the atmospheric pressure. Further, the bypass passage is always filled with a part of the oil pumped from the oil pump. Accordingly, the outlet side of the bypass filter of the bypass passage to which the oil mist recirculation passage is connected has substantially the same environment as that under the oil level of the oil pan. Oil mist does not flow back to the mist separator.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an outline of an oil mist recirculation structure of an engine according to the present invention will be described with reference to FIGS. As shown in the conceptual diagram of FIG. 1, the engine includes an oil pan 2. The oil pan 2 is provided at the bottom of a crankcase (not shown), and stores oil (lubricating oil) 1 for lubricating the bearings and sliding parts of the engine. The suction side of the oil pump 3 is opened in the oil pan 2, and the oil pump 3 pressurizes the oil sucked from the oil pan 2 and sends the oil to the oil supply passage 4 connected to the discharge side. The oil supply passage 4 is connected to a main oil gallery (not shown) of the engine, and a full flow filter 5 is provided in the middle thereof. The full flow filter 5 collects foreign substances in the oil supplied to the main oil gallery and protects the entire oil passage of the engine.

[0010] Full flow filter 5 of oil supply passage 4
An upstream side of the oil supply passage 4 is provided with a bypass supply passage 6 branched from the oil supply passage 4. The bypass passage 6 is a passage through which a part of the oil pumped from the oil pump 3 is diverted and returned to the oil pan 2, and a bypass filter 7 is provided in the middle of the passage. The bypass filter 7 is a filter finer than the full flow filter 5 and removes fine particles such as carbon that cannot be collected by the full flow filter 5 and filters oil. A passage restricting hole 7 for reducing the passage area is provided on the outlet side of the bypass filter 7.
a is provided to limit the amount of oil diverted to the bypass passage 6 to about several percent of the whole.

The oil mist reflux structure according to the present invention comprises:
An oil mist recirculation passage 11 communicating with the mist separator 10 is connected to an outlet side of the bypass filter 7, more specifically, a downstream side of the passage throttle hole 7a of the bypass filter 7. As shown in the overall schematic diagram of FIG. 2, the bypass filter 7 and the full flow filter 5 are generally configured as an integrated oil filter unit 12, and may be mounted outside the engine body 1. Many. Therefore, the oil mist recirculation passage 11 also connects the mist separator 10 and the oil filter unit 12 through the outside of the engine body 1 as shown in FIG. More specifically, the bypass filter 7 is provided on the outer surface of the oil filter unit 12.
An oil passage (not shown) communicating with the outlet side of the oil mist is formed in advance, and an external pipe 11a connected to the mist separator 10 is connected to the oil passage to form an oil mist recirculation passage 11. The external pipe 11a may be a metal pipe or a rubber pipe.

By configuring the oil mist recirculation structure in this way, even if the external pipe 11a vibrates, it does not affect the strength of the oil pan 2 and cracks in the oil pan 2 may cause oil leakage. There is no danger. That is, an oil mist recirculation system that does not affect the reliability of the engine body 1 is established.

[0013] Further, with such a configuration, as in the prior art,
The oil mist separated from the blow-by gas by the mist separator 10 can be reliably returned to the oil pan 2. That is, the bypass filter 7 is a fine-grained filter, and the passage area on the outlet side is restricted by the passage restriction hole 7a, so that the oil pressure loss is large. For this reason, the bypass filter 7 in the bypass passage 6
The hydraulic pressure at the outlet side of is lower than the atmospheric pressure.
The bypass passage 6 is always filled with a part of the oil pumped from the oil pump 3.
That is, the outlet side of the bypass filter 7 of the bypass passage 6 to which the oil mist recirculation passage 11 is connected is connected to the oil pan 2.
Since the environment is substantially the same as that below the oil level, even if the inside of the mist separator 10 becomes negative pressure, the oil in the oil mist recirculation passage 11 is prevented from flowing back to the mist separator 10. .

Hereinafter, embodiments of the present invention will be specifically described. FIG. 3 is a perspective view of the oil filter unit according to the first embodiment of the present invention, partially showing an internal structure thereof. Here, a case will be described in which the oil mist recirculation structure of the engine of the present invention is applied to an engine having a so-called combination type oil filter unit.

As shown in FIG. 3A, in the combination type oil filter unit 20, the full flow filter 21 and the bypass filter 22 are coaxially arranged in series with the bypass filter 22 being on the upper side, and a single cylindrical filter is provided. Of the filter case 23. A filter head 24 is fixed to the head of the filter case 23, and the oil filter unit 20 is attached to the engine body via the filter head 24.

An oil introduction passage 2 for guiding oil from the oil pump in the engine body to the full flow filter 21 and the bypass filter 22 is provided in the filter head 24.
5 and an oil outlet passage 26 for guiding the filtered oil to a main oil gallery in the engine body. The oil introduction passage 25 is provided between the inner peripheral surface of the filter case 23 and the full flow filter 21 and the bypass filter 2.
2 is connected to a cylindrical gap space 30 defined by a gap with the outer peripheral surface. On the other hand, the oil outlet passage 26 penetrates the center of the bypass filter 22 and is connected to an internal space 31 defined by the inner peripheral surface of the full flow filter 21. In the present embodiment, the path from the oil pump to the main oil gallery via the oil introduction passage 25, the gap space 30, the full flow filter 21, the internal space 31, and the oil outlet passage 26 is the oil supply passage described above (FIG. 1).
4).

The filter head 24 has a structure shown in FIG.
As shown in (b), an oil return passage 27 for returning oil from the oil filter unit 20 to the oil pan is also formed. The oil return passage 27 is connected to a cylindrical internal space 32 defined by an inner peripheral surface of the bypass filter 22 and an outer peripheral surface of the oil outlet passage 26. As a result, of the oil introduced from the oil introduction passage 25 into the clearance space 30 inside the filter case 23, a part of the oil flowing into the outer peripheral surface of the bypass filter 22 is filtered in the bypass filter 22 and then filtered. 2
The oil flows into the inner space 32 inside and returns to the oil pan through the oil return passage 27 of the filter head 24. Therefore, in the present embodiment, the bypass filter 2
The path from the oil passage 2 to the oil pan via the internal space 32 and the oil return passage 27 is the above-described bypass passage (FIG. 1).
6). Further, the bypass passage has a reduced passage area at a connection portion between the internal space 32 and the oil return passage 27, and this connection portion is connected to the above-described passage throttle hole (FIG.
7a).

In the present embodiment, the oil mist is recirculated to the oil return passage 27 formed in the filter head 24 corresponding to the above-mentioned "bypass passage outlet side of the bypass passage". In particular,
A communication hole 35 for communicating the oil return passage 27 with the outside is formed in the filter head 24, and an external pipe (a pipe, a hose or the like) 36 communicating with a mist separator (not shown) is connected to the communication hole 35. Thus, the above-mentioned oil mist circulation passage (reference numeral 11 in FIG. 1) is formed. As described above, the oil mist recirculation structure of the engine of the present invention can be easily applied to an engine having a general combination type oil filter unit 20.

Next, FIG. 4 is a perspective view of an oil filter unit according to a second embodiment of the present invention, partially showing an internal structure thereof. Here, a case where the oil mist recirculation structure of the engine of the present invention is applied to an engine having a so-called separate type oil filter unit will be described.

As shown in FIG. 4, in a separate type oil filter unit 40, a full flow filter 4 is provided.
1 and the bypass filter 42 are arranged in parallel and housed in separate filter cases 43 and 44, respectively. A common filter head 45 is fixed to the heads of the filter cases 43 and 44, and the oil filter unit 40 is attached to the engine body via the filter head 45.

An oil introduction passage 46 for guiding oil from the oil pump in the engine body to the full flow filter 41 is provided on the full flow filter 41 side of the filter head 45, and the oil filtered by the full flow filter 41 is supplied to the main oil in the engine body. An oil lead-out passage 47 for leading to the gallery is formed. Oil introduction passage 46
Is connected to a cylindrical space 50 defined by a gap between the inner peripheral surface of the filter case 43 and the outer peripheral surface of the full flow filter 41. On the other hand, the oil outlet passage 47 is connected to an internal space 51 defined by the inner peripheral surface of the full flow filter 41. In the present embodiment, the oil pump allows the oil introduction passage 46, the cylindrical space 50, the full flow filter 4
The path leading to the main oil gallery via the internal space 51 and the oil outlet passage 47 corresponds to the above-described oil supply passage (reference numeral 4 in FIG. 1).

Further, between the filter cases 43 and 44,
A flow dividing passage 48 is provided for dividing a part of the oil introduced into the cylindrical space 50 inside the filter case 43 to the filter case 44 side. The branch passage 48 is connected to a cylindrical gap 52 defined by a gap between the inner peripheral surface of the filter case 44 and the outer peripheral surface of the bypass filter 42. Furthermore, the bypass filter 4 of the filter head 45
An oil return passage 49 for returning oil from the oil filter unit 40 to the oil pan is also formed on the second side. The oil return passage 49 is connected to an internal space 53 defined by the inner peripheral surface of the bypass filter 42. As a result, the oil introduced from the branch passage 48 into the interstitial space 52 inside the filter case 44 is filtered in the bypass filter 42, flows into the internal space 53 inside the bypass filter 42, and returns to the oil in the filter head 45. It returns to the oil pan through the passage 49.

Therefore, in this embodiment, the branch passage 4
The path from 8 to the oil pan via the clearance space 52, the bypass filter 42, the internal space 53, and the oil return passage 49 corresponds to the above-described bypass passage (reference numeral 6 in FIG. 1). Further, the bypass passage has a reduced passage area at a connection portion between the internal space 53 and the oil return passage 49, and
This connection portion corresponds to the above-described passage throttle hole (reference numeral 7a in FIG. 1).

In the present embodiment, the oil mist is recirculated to the oil return passage 49 of the filter head 45 corresponding to the above-mentioned "pass filter outlet side of the bypass passage". Specifically, a communication hole 55 for communicating the oil return passage 49 with the outside is formed in the bypass filter 42 of the filter head 45, and an external pipe (not shown) communicating with the communication hole 55 to a mist separator (not shown). The above-mentioned oil mist recirculation passage (reference numeral 11 in FIG. 1) is formed by connecting a pipe or a hose 56). Thus, the oil mist recirculation structure of the engine of the present invention can be easily applied to an engine having the separate type oil filter unit 40.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and can be implemented with various modifications without departing from the spirit of the present invention. . For example, it is of course possible to apply the present invention to an engine having an oil filter unit of another type other than the above-described embodiment. Further, it is needless to say that the present invention can be applied to an engine in which the full flow filter and the bypass filter are provided separately from each other instead of being integrated.

[0026]

As described in detail above, according to the oil mist recirculation structure of the engine of the present invention, the oil mist return passage separated by the mist separator is connected to the bypass filter outlet side of the bypass passage. This has the effect that the oil mist can be reliably returned from the mist separator to the oil pan without affecting the strength of the oil pan.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram for explaining an outline of an oil mist recirculation structure of an engine of the present invention.

FIG. 2 is a schematic view of the entire engine for explaining an outline of an oil mist recirculation structure of the engine of the present invention.

FIGS. 3A and 3B are perspective views of the oil filter unit according to the first embodiment of the present invention, partially broken away to show an internal structure, wherein FIG. 3A is an overall configuration diagram, and FIG. a)
FIG. 3 is a partial configuration diagram when viewed from another angle.

FIG. 4 is a perspective view of an oil filter unit according to a second embodiment of the present invention, showing a partially broken internal structure.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Engine main body 2 Oil pan 3 Oil pump 4 Oil supply passage 5, 21, 41 Full flow filter 6 Bypass passage 7, 22, 42 Bypass filter 7a Passage throttle hole 10 Mist separator 11 Oil mist circulation passage 11a, 36, 56 Oil mist reflux External pipes constituting passages 12, 20, 40 Oil filter units 22, 23, 43, 44 Filter cases 24, 45 Filter heads 25, 46 Oil introduction passages 26, 47 constituting oil supply passages Oil constituting oil supply passages Outlet passages 27, 49 Oil return passages 35, 55 constituting a bypass passage Communication holes constituting an oil mist recirculation passage

Claims (1)

[Claims] 1. An oil mist recirculation structure for an engine that recirculates oil mist separated from blow-by gas by a mist separator to an oil pan, wherein a part of oil pumped from an oil pump is returned to the oil pan. A bypass filter provided in the middle of the bypass passage for filtering oil flowing through the bypass passage; and an oil mist recirculation passage for communicating the mist separator with an outlet side of the bypass filter of the bypass passage. An oil mist recirculation structure for an engine.