JP2001182520A - Blowby gas returning device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent engine oil from being sucked up from a drain pipeline. SOLUTION: An oil passage 22 formed inside the peripheral wall of a cylinder 12a connects a crank case 16 to a cylinder head 17, and a gas circulating pipeline 24 communicating the cylinder head with an intake passage 23 returns blowby gas of the cylinder head to the intake passage. A filter 25 provided in the gas circulating pipeline separates engine oil 14 from the blowby gas, and a drain pipeline 26 returns the engine oil separated with the filter to the crank case. A check valve 36 provided in the drain pipeline permits the engine oil to flow from the filter to the crank case, and prevents its reverse flow. A connection of the drain pipeline with the crank case is formed at a position higher than the engine oil level in the crank case, and a visor 34 for covering at least the upper part of the connection is projected by provided in the crank case.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for returning blow-by gas leaked from an engine cylinder to a crankcase to intake air. More specifically, the present invention relates to a device that removes engine oil contained in blow-by gas of a diesel engine and then returns the blow-by gas to intake air.

[0002]

2. Description of the Related Art Conventionally, a filter device has been disclosed as a device for removing engine oil contained in blow-by gas (JP-A-6-58132). The filter device includes a housing having an inlet portion formed at a lower portion and an outlet portion formed at an upper portion, and a filtering material filled in the housing. The inlet is connected to the crankcase via a first hose, and the outlet is connected to the intake passage of the engine via a second hose. In the filter device configured as described above, blow-by gas (including engine oil) leaking into the crankcase is introduced into the housing from the inlet through the first hose, and after the engine oil is separated by the filtering material. , Blow-by gas is second from the outlet
It is sent to the cylinder of the engine through a hose and an intake passage. On the other hand, the engine oil separated by the filter material is returned to the crankcase from the inlet through the first hose. As a result, the blow-by gas does not need to be released to the atmosphere.

[0003]

However, in the filter device disclosed in the above-mentioned conventional Japanese Patent Application Laid-Open No. 6-58132, the connection of the first hose to the crankcase is caused by the engine oil flowing down the inner wall surface of the crankcase. Blocked,
If the pressure in the housing becomes lower than that in the crankcase due to the negative pressure of the intake air in this state, there is a possibility that engine oil may be sucked from the crankcase toward the housing. An object of the present invention is to provide an engine blow-by gas that can reliably separate engine oil from blow-by gas containing engine oil and prevent engine oil in a crankcase from being sucked up from a drain pipe. A reduction device is provided.

[0004]

The invention according to claim 1 is
As shown in FIGS. 1 and 2, an oil passage 22 formed inside the peripheral wall of the cylinder 12 a and communicating between the crankcase 16 and the cylinder head 17 is provided.
A gas recirculation line 24 for communicating blow-by gas leaking from the cylinder 12 a to the crankcase 16 to the intake passage 23 through the oil passage 22 and the cylinder head 17, and a gas recirculation line 24. 24
A filter 25 connected to a lower end of the filter 25 and the crankcase 16 and returning the engine oil 14 separated by the filter 25 to the crankcase 16; A check valve 36 provided in a pipe 26 to allow the flow of the engine oil 14 from the filter 25 to the crankcase 16 and to prevent the flow of the engine oil 14 from the crankcase 16 to the filter 25. In the gas reducing device, a connection part of the drain line 26 to the crankcase 16 is formed at a position higher than a liquid level of the engine oil 14 in the crankcase 16, and a connection part of the drain line 26 to the crankcase 16 is provided. Of the crankcase 16
It is characterized by being protruded inside.

In the blow-by gas reducing device for an engine according to the present invention, the blow-by gas leaked from the cylinder 12a to the crankcase 16 contains the engine oil 14, and the blow-by gas is supplied to the oil passage 22,
The oil flows into the filter 25 through the cylinder head 17 and the gas recirculation line 24, and the engine oil 14 is separated from the blow-by gas by the filter 25. The blow-by gas from which the engine oil 14 has been removed flows into the intake passage 23 through the gas recirculation pipe 24, and is burned in the cylinder 12a. On the other hand, the engine oil 14 separated by the filter 25 passes through the drain line 26 and
Returned to 6. At this time, the engine oil 14 flowing down the inner wall surface of the crankcase 16 flows down through the outer surface of the eave 34, so that the connection of the drain pipe 26 to the crankcase 16 is not blocked by the engine oil 14. As a result, using the check valve whose opening / closing timing is slightly delayed from the pressure fluctuation, the filter 25 is operated by the negative pressure of the intake air.
Even if the pressure inside the crankcase 16 is lower than that inside the crankcase 16, the engine oil 14 will not be sucked up through the drain pipe 26.

According to a second aspect of the present invention, as shown in FIG. 6, the connection of the drain line 56 to the crankcase 16 is formed at a position higher than the level of engine oil in the crankcase 16, and The connecting portion of the passage 56 to the crankcase has a cylindrical projecting portion 56b projecting into the crankcase 16 longer than the thickness of the engine oil flowing down along the inner wall surface of the crankcase 16. In the blow-by gas reducing device for an engine according to the second aspect, the engine oil flowing down on the inner wall surface of the crankcase 16 flows down through the outer peripheral surface of the projection 56b protruding into the crankcase 16, so that the drain pipe The connection of the passage 56 to the crankcase 16 is not blocked by the engine oil. As a result, even if the pressure in the filter drops below the crankcase 16 due to the negative pressure of the intake air, the engine oil passes through the drain line 56 using the check valve whose opening / closing timing is slightly delayed from the pressure fluctuation. It cannot be sucked.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a first embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the engine 11 is a diesel engine.
In the upper part of the cylinder block 12, a plurality of cylinders 12
a is formed. Skirt part 1 of cylinder block 12
An oil pan 13 is attached to the lower surface of 2b, and a skirt portion 12b and the oil pan 13 constitute a crankcase 16 that stores a crankshaft (not shown) and stores engine oil 14. A cylinder head 17 is provided on the upper surface of the cylinder block 12. The cylinder head 17 has a head body 17a attached to the upper surface of the cylinder block 12, and a head cover 17c that covers the upper surface of the head body 17a. A valve system (not shown) such as a rocker arm is accommodated in a head chamber 17c surrounded by the head main body 17a and the head cover 17b.
Engine oil 14 for lubrication is supplied to the head chamber 17c.

The blow-by gas recirculation device of the present invention is a gas recirculation pipe for connecting and connecting an oil passage 22 formed inside the peripheral wall of a cylinder 12a, a head chamber 17c and an intake passage 23 (intake manifold or intake pipe) of the engine 11. Road 24
, A filter 25 provided in the gas recirculation line 24, and a drain line 26 connecting the lower end of the filter 25 and the crankcase 16. The oil passage 22 is formed in the cylinder block 12 and the head body 17a so as to communicate the crankcase 16 with the head chamber 17c. The engine oil 14 in the head chamber 17c returns to the crankcase 16 through the oil passage 22. It is configured as follows. The gas recirculation line 24 is configured to return blow-by gas leaked to the crankcase 16 from the gap between the cylinder 12a and the piston ring 27 to the intake passage 23 through the oil passage 22 and the head chamber 17c. The blow-by gas contains the engine oil 14.

As shown in detail in FIG. 3, the filter 25 has an inlet 28a and an outlet 28b on the left and right sides and a through hole 28c in the lower center, and a filter on the lower surface of the filter head 28. And a filter case 32 which is attached via the holding portion 29 and in which the filter body 31 is accommodated. A pressure regulating valve 33 is provided in the filter head 28. This pressure regulating valve 33
Is a diaphragm 33a whose outer peripheral edge is attached to the upper center of the filter head 28, a valve body 33b which is attached to the central lower surface of the diaphragm 33a and can open and close the through hole 28c, and a direction in which the valve body 33b is separated from the through hole 28c. (Compression coil spring). The pressure regulating valve 33 is normally kept open by the elastic force of the spring 33c, and when the suction force due to the negative pressure of the intake air exceeds a predetermined value,
The diaphragm 33a is configured to deform and close against the elastic force of the spring 33c. At the center of the filter holding portion 29, a shaft portion 29a into which a cylindrical filter body 31 can be fitted is projected downward, and a gas introduction hole 29b extending in the axial direction and having a closed lower end is formed in the shaft portion 29a. Is done. Further, a window portion 29c facing the inner peripheral surface of the filter main body 31 is formed in a portion of the shaft portion 29a where the filter main body 31 is fitted. The filter body 31 is configured to separate the engine oil 14 from the blow-by gas when the blow-by gas including the engine oil 14 passes therethrough.

The drain pipe 26 has a first short pipe 26a (FIG. 4) protruding from the lower end of a check valve 36 described later and a second short pipe protruding outward from the skirt portion 12b of the cylinder block 12. A tube 26b (FIG. 2) and first and second short tubes 26 at both ends.
a and 26b (FIGS. 1 and 2) respectively fitted into the hoses 26a and 26b. The second short pipe 26b is provided at a position higher than the level of the engine oil 14 in the crankcase 16 (FIG. 1). The reason why the second short pipe 26b was not provided at a position soaked in the engine oil 14 stored in the crankcase 16 is that the filter case 32
If the pressure inside the crankcase 16 becomes smaller than the pressure inside the crankcase 16, the engine oil 14 may be sucked up through the drain line 26, and the filter 25 may be moved to a high position above the pressure difference, that is, the engine inside the crankcase 16. This is because it is necessary to mount the filter 25 at a high position where the oil 14 does not flow into the filter case 32, which restricts the installation position of the filter 25. Further, an eave 34 is provided on the inner wall surface of the skirt portion 12b to cover at least the upper portion of the base end opening 26d of the second short pipe 26b (FIGS. 1 and 2). The eaves 34 include a horizontal piece 34a that covers the upper edge of the base end opening 26d, and a vertical piece 34b that hangs down from the tip of the horizontal piece 34a. Further, the eaves 34 may have a pair of side edge cover pieces (not shown) that cover both side edges of the base opening 26d.

A check valve 36 is provided at the upper end of the drain line 26, that is, at the lower end of the filter case 32, as shown in FIGS.
And FIG. 5). The check valve 36 is a cylindrical valve case 36.
a and a disc-shaped valve body 36b housed in the case 36a so as to be vertically movable. A concave groove 36c is formed on the lower surface of the valve case 36a, and the outer diameter of the valve body 36b is formed smaller than the inner diameter of the valve case 36a. That is, the engine oil 14 can flow into the concave groove 36c through the gap between the outer peripheral surface of the valve main body 36b and the inner peripheral surface of the valve case 36a in a state where the valve main body 36b is in close contact with the bottom surface of the valve case 36a. Is done. When the pressure in the filter case 32 is equal to or larger than the pressure in the crankcase 16 when the weight of the valve body 36b is ignored, the check valve 36 has a lower surface of the valve case 36a. To the engine oil 1 in the filter case 32
4 is allowed to flow into the crankcase 16 through the concave groove 36c and the drain conduit 26, and when the pressure in the filter case 32 becomes smaller than the pressure in the crankcase 16, the valve body 36b rises and the valve case The filter case 32 is configured to be in close contact with the upper surface of the filter case 36a and to prevent the crankcase 16 from flowing back to the filter case 32 through the drain line 26. The check valve 36 has a time lag until the valve body 36b rises and comes into close contact with the upper surface of the valve case 36a even if the pressure in the filter case 32 becomes smaller than the pressure in the crankcase 16, that is, the reverse lag occurs. Since the opening / closing timing of the stop valve 36 is slightly delayed from the pressure fluctuation, the blow-by gas in the crankcase 16
2 may flow slightly into the interior.

The operation of the blow-by gas returning device thus configured will be described. When fuel burns in the cylinder 12a, the blow-by gas leaks into the crankcase 16 from the gap between the cylinder 12a and the piston ring 27 due to the rapid pressure rise. Since the blow-by gas comes into contact with the engine oil 14 attached to the inner peripheral surface of the cylinder 12a when passing through the gap, the blow-by gas contains a relatively large amount of the engine oil 14. The blow-by gas flows into the filter 25 from the inlet 28a through the oil passage 22, the head chamber 17c, and the gas recirculation line 24. Filter 25
The blow-by gas flowing into the gas inlet hole 29b of the shaft portion 29a flows through the gap between the valve body 33b of the pressure regulating valve 33 and the through hole 28c as shown by a solid line arrow in FIG. Then, the gas flows into the filter main body 31 from the inner peripheral surface of the filter main body 31. At this time, the engine oil 14 contained in the blow-by gas is separated by the filter body 31. The blow-by gas from which the engine oil 14 has been removed flows out from the outer peripheral surface of the filter main body 31 as shown by a dashed arrow, flows into the intake passage 23 through the outlet 28b and the gas recirculation line 24, and further flows into the cylinder 12a. It is burned.

On the other hand, the engine oil 14 separated by the filter 25 accumulates at the lower end of the filter case 32, passes through the valve case 36a of the check valve 36 and the concave groove 36c, and further passes through the first short pipe 26a of the drain line 26. , Hose 26c and second
It is returned to the crankcase 16 through the short pipe 26b. At this time, the engine oil 14 flowing down the inner wall surface of the crankcase 16 flows down through the outer surface of the eave 34,
The proximal opening 26d of the short pipe 26b is not blocked by the engine oil 14. As a result, when the pressure in the filter case 32 falls below that in the crankcase 16 due to the negative pressure of the intake air, and the opening / closing timing of the check valve 36 is slightly delayed from the pressure fluctuation, the blow-by gas in the crankcase 16 Although flowing into the case 32, the engine oil 14 is not sucked up through the drain line 26.

FIG. 6 shows a second embodiment of the present invention.
6, the same reference numerals as those in FIG. 2 indicate the same parts. In this embodiment, the second short pipe 56a of the drain conduit 56 is longer than the film thickness of the engine oil flowing down along the inner wall surface of the crankcase 16 and is substantially horizontal without using the eaves of the first embodiment. Has a cylindrical projection 56b projecting into the crankcase 16. Except for the above, the configuration is the same as that of the first embodiment. In the blow-by gas reducing device configured as described above, the engine oil flowing down the inner wall surface of the crankcase 16 flows down through the outer peripheral surface of the protruding portion 56b of the second short pipe 56a. Is not blocked by engine oil.
In this embodiment, if the second short pipe 56a is extended to form the protruding portion 56b, the first embodiment requires a special part called an eave (when the eave is welded to the inner wall surface of the crankcase). Compared with the embodiment, the number of parts does not increase, and the mounting cost can be reduced. Operations other than those described above are substantially the same as those in the first embodiment, and thus, repeated description will be omitted.

[0015]

As described above, according to the present invention, the blow-by gas containing the engine oil in the crankcase flows into the filter through the oil passage, the cylinder head and the gas recirculation line, and is blow-by by the filter. Since the engine oil is separated from the gas, the blow-by gas from which the engine oil has been removed flows into the intake pipe. On the other hand, the engine oil separated by the filter is returned to the crankcase through the drain pipe. As a result, the engine oil can be reliably separated from the blow-by gas containing the engine oil. Also, the connection of the drain pipe to the crankcase is formed at a position higher than the engine oil level in the crankcase, and an eave covering at least the upper part of this connection is projected into the crankcase. The engine oil flowing down the wall surface flows down through the outer surface of the eaves, and the connection of the drain pipe to the crankcase is not blocked by the engine oil. As a result,
Using a check valve whose opening / closing timing is slightly delayed from the pressure fluctuation, even if the pressure inside the filter falls below the inside of the crankcase due to the negative pressure of the intake air, the engine oil will not be sucked up through the drain line. Absent.

A connection portion of the drain line to the crankcase is formed at a position higher than the level of the engine oil in the crankcase, and the connection portion is formed based on a film thickness of the engine oil flowing down along the inner wall surface of the crankcase. If there is a long cylindrical protrusion protruding into the crankcase, the engine oil flowing down the inner wall surface of the crankcase flows down through the outer peripheral surface of the protrusion, so that the connection portion is not blocked by the engine oil. As a result, using a check valve whose opening / closing timing is slightly delayed from the pressure fluctuation, even if the pressure inside the filter falls below the inside of the crankcase due to the negative pressure of the intake air, engine oil is sucked up through the drain pipe. It will not be done.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a blow-by gas returning device according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a portion A in FIG.

FIG. 3 is a longitudinal sectional view of a filter.

FIG. 4 is an enlarged sectional view of a portion B in FIG. 3;

FIG. 5 is a sectional view taken along line CC of FIG. 4;

FIG. 6 is a sectional view illustrating a second embodiment of the present invention and corresponding to FIG. 2;

[Explanation of symbols]

 11 Engine 12a Cylinder 14 Engine Oil 16 Crankcase 17 Cylinder Head 22 Oil Passage 23 Intake Passage 24 Gas Recirculation Pipeline 25 Filter 26, 56 Drain Pipeline 34 Eave 36 Check Valve 56b Projection

Claims (2)

[Claims] An oil passage (22) formed inside a peripheral wall of a cylinder (12a) and communicating between a crankcase (16) and a cylinder head (17), and an oil passage (22) between the cylinder head (17) and an engine (11). Intake passage (23)
The blow-by gas leaked from the cylinder (12a) to the crankcase (16) is connected to the oil passage (22).
And the intake passage (23) through the cylinder head (17).
A gas recirculation pipe (24), a filter (25) provided in the gas recirculation pipe (24) for separating engine oil (14) from the blow-by gas, a lower end of the filter (25) and the crank A drain line (26) for connecting the case (16) and returning the engine oil (14) separated by the filter (25) to the crankcase (16)
The drain pipe (26) is provided in the filter (25) to allow the flow of the engine oil (14) from the filter (25) to the crankcase (16) and from the crankcase (16) to the filter (2
Check valve (36) that blocks the flow of engine oil (14) to 5)
A blow-by gas reducing device for an engine, comprising: a connection portion of the drain line (26) to the crankcase (16), which is higher than a liquid level of engine oil (14) in the crankcase (16). An eave (34) formed at a high position and covering at least an upper portion of a connection portion of the drain pipe (26) to the crankcase (16) is provided in the crankcase.
(16) A blow-by gas returning device for an engine, wherein the device is protruded from the inside. 2. An oil passage formed inside a peripheral wall of a cylinder and connecting the crankcase (16) to the cylinder head, and an oil passage connecting the cylinder head and an intake passage of an engine to connect the cylinder case to the crankcase (16). A) a gas recirculation pipe returning the blow-by gas leaked to the intake passage through the oil passage and the cylinder head to the intake passage; a filter provided in the gas recirculation pipe to separate engine oil from the blow-by gas; A drain pipe (56) connecting the lower end of the filter to the crankcase (16) and returning engine oil separated by the filter to the crankcase (16); and a filter provided in the drain pipe (26). To allow the engine oil to flow from the crankcase (16) to the filter and the engine A blow-by gas reducing device for an engine comprising a check valve for preventing the flow of oil, wherein a connection portion of the drain line (56) to the crankcase (16) is provided in the crankcase (16). The film thickness of the engine oil formed at a position higher than the liquid level of the engine oil, wherein the connection part of the drain pipe (56) to the crankcase (16) flows down along the inner wall surface of the crankcase (16) A blow-by gas reducing device for an engine, comprising a cylindrical projection (56b) protruding into the crankcase (16) for a long time.