US20080127953A1

US20080127953A1 - Engine Head Cover Assembly Having An Integrated Oil Separator

Info

Publication number: US20080127953A1
Application number: US11/565,872
Authority: US
Inventors: Teng-Hua Shieh; Naveen Rajan; Wei Liu
Original assignee: Toyota Engineering and Manufacturing North America Inc
Current assignee: Toyota Motor Engineering and Manufacturing North America Inc
Priority date: 2006-12-01
Filing date: 2006-12-01
Publication date: 2008-06-05
Also published as: EP2087212A4; WO2008070514A3; WO2008070514A2; EP2087212A2; JP2010511827A; JP2014074414A; JP6096684B2

Abstract

A head cover assembly for covering a crankcase of an internal combustion engine includes a head cover and an integral oil separator. The oil separator includes a housing that defines a flow path that separates oil from crankcase gases passing therethrough. At least a portion of the housing is integrally formed along an inner surface of the head cover.

Description

FIELD OF THE INVENTION

The invention relates to an engine head cover for an internal combustion engine. More particularly, the invention relates to an engine head cover having an integrated oil separator for separating oil from crankcase gases during operation of the engine.

BACKGROUND OF THE INVENTION

An internal combustion engine typically includes a combustion chamber, where a fuel air mixture is burned to cause movement of a set of reciprocating pistons, and a crankcase, which contains the crankshaft driven by the pistons. During operation, it is normal for the engine to experience “blow-by,” wherein combustion gases leak past the piston-cylinder gap from the combustion chamber and into the crankcase. These blow-by or crankcase gases contain moisture, acids and other undesired by-products of the combustion process.
An engine typically includes a Positive Crankcase Ventilation (PCV) system for removing harmful gases from the engine and prevents those gases from being expelled into the atmosphere. The PCV system does this by using manifold vacuum to draw vapors from the crankcase into the intake manifold. Vapor is then carried with the fuel/air mixture into an intake manifold of the combustion chambers where it is burned. Generally, the flow or circulation within the system is controlled by the PCV valve, which acts as both a crankcase ventilation system and as a pollution control device.
It is normal for crankcase gases to also include a very fine oil mist. The oil mist is carried by the PCV system to the manifold. The oil mist is then burned in the combustion chamber along with the fuel/air mixture. This results in an increase in oil consumption. A known method of removing oil from the crankcase gases is to use an oil separator. The crankcase gases flow through the oil separator. Localized high pressure areas in the oil separator promote separation of oil from the gases. The oil is re-introduced back to a sump via a drain device. The sump generally holds excess oil in the system.
It remains desirable to provide an improved oil separator that is more efficient than conventional oil separator designs in the removal of oil from crankcase gases. It also remains desirable to provide an oil separator that is compact in size and integral with a part of the engine housing, such as a head cover, in order to reduce the packaging space occupied by the oil separator inside of the engine.

SUMMARY OF THE INVENTION

According to one aspect of the invention, a head cover assembly is provided for covering a crankcase of an internal combustion engine. The head cover assembly includes a head cover and an oil separator. The head cover has opposite outer and inner surfaces. The oil separator separates oil from crankcase gases passing therethrough. The oil separator has a housing disposed along an inner surface of the head cover. The housing has at least one side wall integral with the head cover, which together with the head cover define an interior space of the oil separator.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

FIG. 1 is a bottom view of a head cover assembly having an integral oil separator according to one embodiment of the invention;

FIG. 2 is an enlarged bottom view of a portion of the head cover assembly shown in FIG. 1;

FIG. 3 is an exploded perspective bottom view of the head cover assembly of FIG. 1;

FIG. 4 is a bottom view of a head cover assembly according to a second embodiment of the invention;

FIG. 5 is an enlarged bottom view of a portion of the head cover assembly shown in FIG. 4;

FIG. 6 is a top perspective view of the head cover assembly of FIG. 4;

FIG. 7 is an enlarged exploded top perspective view of a portion of the head cover assembly of FIG. 4;

FIG. 8 is an enlarged exploded perspective view of a portion of the head cover assembly according to a third embodiment of the invention;

FIG. 9 is an enlarged perspective view of a portion of the head cover assembly of FIG. 8 showing a side of an oil separator cap with a tab for securing the cap to a head cover; and

FIG. 10 is a cross sectional view of the head cover assembly of FIG. 8 illustrating the slot for lockingly receiving the tab for securing the cap to the head cover.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1-3, a head cover assembly for enclosing a crankcase of an internal combustion engine is generally indicated at 10. The head cover assembly 10 includes a head cover 12 having opposite outer 14 and inner 16 surfaces. The head cover assembly 10 also includes an oil separator 20 for removing oil from crankcase gases in the engine. The oil separator 20 includes a housing 30 disposed along the inner surface 16 of the head cover 12. The housing 30 has a plurality of side walls 22, 24, 26, 28 integrally formed with the head cover 12. At least one of the side walls 28 extends along the inner surface 16 of the head cover 12, while the remaining side walls 22, 24, 26 extend outwardly from the inner surface 16 of the head cover 12. Alternatively, all of the side walls of the housing extend outwardly from the inner surface of the head cover. The head cover may be formed from steel, aluminum or any material or combination of materials known by those skilled in the art, which are suitable for use in the heat and the environment associated with the engine and which allows integral formation of at least portions of the oil separator housing with the head cover.
A portion of the head cover 12 extends between the side walls 22, 24, 26, 28 to form an interior space. A plate 40 cooperates with the side walls 22, 24, 26, 28 to enclose the interior space of the oil separator 20. The head cover 12 has at least one threaded bore 29 for securing the plate 40 to the side walls 22, 24, 26, 28 using a bolt. A gasket (not shown) may be disposed between the side walls 22, 24, 26, 28 and the plate 40 to prevent gases from leaking from the interior space of the housing 30. Alternatively, the housing may have a generally cylindrical side wall that extends from the inner surface of the head cover instead of the straight side walls of the illustrated embodiment. The plate would then have a generally circular shape to cooperate with the generally cylindrical shape of the side wall.
The housing 30 of the oil separator 20 includes an inlet and an outlet. A plurality of guide walls 43 extend from the head cover 12 toward the plate 40 to define a path 39 that directs crankcase gases through the housing 30. The path 39 is shaped to promote separation of oil from crankcase gases as the gases flow through the path 39 between the inlet and outlet. The separated oil is collected in the housing 30 and re-introduced to the oil sump (not shown) for re-use in the engine.
A second embodiment of the head cover assembly 110 is shown in FIGS. 4-7, wherein like parts are indicated by numerals offset by 100. In this embodiment, the housing 130 is formed by a cap 41, a cover plate 45 and a cylindrical side wall 50, which together define the interior space of the oil separator 120. More specifically, the cylindrical side wall 50 is formed integrally with the head cover 112 and defines a recess for receiving the cap therein. More specifically, the cap 41 includes an annular portion 40 with threads 42 for engaging mating threads 44 on the head cover 112.
During assembly, the cap 41 is inserted into the recess formed by the cylindrical side wall 50. The cap 41 is then turned about its longitudinal axis to cause threading engagement between the threads 42 on the cap 41 and mating threads 44 formed in the cylindrical side wall 50, thereby securing the cap 41 to the head cover 112. The cap 41 is fully inserted when it contacts a locating surface 52 formed head cover 112 adjacent a bottom end of the cylindrical side wall 50. The cover plate 45 is disposed between the cap 41 and the head cover 112. The plurality of guide walls 143 extend from the cover plate 45 to define the flow path for crankcase gases passing through the oil separator 120.
A third embodiment of the head cover assembly 210 are shown in FIGS. 8-11. In this embodiment, the threads from the second embodiment are replaced with a tab and slot arrangement, wherein a tab 60 extends outwardly from the annular portion 240 of the cap 241 and a guide slot 62 is formed in the cylindrical side wall 250. The guide slot 62 extends in a generally longitudinal direction along the cylindrical side wall 250. A key slot 68 extends generally orthogonally from an end 66 of the guide slot 62. During assembly, the cap 241 of the housing 230 is inserted into the recess defined by the cylindrical side wall 250. The tab 60 slides in the guide slot 62 toward the key slot 68. The cap 241 is fully inserted when it contacts the locating surface 252 at the bottom of the recess. The cap 241 is then turned so that the tab 60 slides into the key slot 68, thereby securing the oil separator 220 to the head cover 212. Alternatively, the tab and slot arrangement may be reversed, wherein the tab extends from the head cover and the slot is formed in the cap.
In the illustrated embodiments, the guide walls are arranged in the form of a labyrinth, which promotes the separation of oil from the crankcase gases as the gases flow therealong. Alternatively, the oil separator may be a cyclone type oil separator, wherein the guide wall is a coil that defines a spiral-shape flow path that extends between the inlet and the outlet of the housing. It should be appreciated by those having ordinary skill in the art that other types of oil separators may be packaged within the housing. Alternatively, the oil separator may incorporate more than one type of oil separating arrangement within the housing, such as a combination between labyrinth and cyclone type oil separating arrangements.
The invention has been described in an illustrative manner. It is, therefore, to be understood that the terminology used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the invention are possible in light of the above teachings. Thus, within the scope of the appended claims, it is clear that the invention may be practiced other than as specifically described.

Claims

1. A head cover assembly for covering a crankcase of an internal combustion engine, said head cover assembly comprising:

a head cover having opposite outer and inner surfaces; and

an oil separator for separating oil from crankcase gases passing therethrough, the oil separator having a housing disposed along an inner surface of the head cover, the housing having at least one side wall integral with the head cover, which together with the head cover define an interior space of the oil separator.

2. A head cover assembly as set forth in claim 1, wherein the housing is formed by a plurality of side walls, one of the side walls extending along the inner surface of the head cover.

3. A head cover assembly as set forth in claim 2 including a plate releasably attached to the side walls to enclose the interior space of the oil separator.

4. A head cover assembly as set forth in claim 3, wherein the oil separator includes a plurality of guide walls that are integral with the head cover and extend between the inner surface and the plate to define a labyrinth path that causes separation of oil from crankcase gases passing therethrough.

5. A head cover assembly as set forth in claim 1, wherein the at least one side wall is cylindrically shaped to define a cylindrical recess in the head cover.

6. A head cover assembly as set forth in claim 5 including a cap releasably attachable to the at least one side wall to define the interior space of the oil separator.

7. A head cover assembly as set forth in claim 6, wherein the cap includes threads for engaging mating threads on the at least one side wall.

8. A head cover assembly as set forth in claim 7 including a cover plate disposed between the cap and the head cover to enclose the interior space of the oil separator.

9. A head cover assembly as set forth in claim 8 including guide walls extending from the cover plate toward the cap to define an oil path for separating oil from crankcase gases passing therethrough.

10. A head cover assembly as set forth in claim 6, wherein the cap and the at least one side wall are coupled to each other by a tab and slot arrangement, wherein the cap is rotated relative to the at least one side wall to cause locking engagement between a tab and a key slot.

11. A head cover assembly as set fort in claim 10, wherein the tab extends outwardly from the cap and the key slot is formed in the at least one side wall.

12. A head cover assembly as set forth in claim 11, wherein the at least one side wall is generally cylindrical and forms a recess for receiving the cap therein.

13. A head cover assembly as set forth in claim 12, wherein the at least one side wall includes a guide slot that receives the tab from the cap as the cap is inserted into the recess.

14. A head cover assembly as set forth in claim 13, wherein the key slot extends orthogonally from an end of the guide slot so that rotation of the cap within the recess causes locking engagement between the tab and the key slot.