Oil Separators
An oil separator for trapping oil mist contained in blow-by gas includes a separation plate, an upstream oil-mist trapping chamber, and a downstream oil-mist trapping chamber. The upstream and downstream oil-mist trapping chambers are divided by the separation plate. The upstream oil-mist trapping chamber communicates with a flow inlet for blow-by gas. The downstream oil-mist trapping chamber communicates with the upstream oil-mist trapping chamber and communicates with a flow outlet for blow-by gas. A return port formed through the separation plate returns oil mist trapped in the downstream oil-mist trapping chamber into the upstream oil-mist trapping chamber. The return port is positioned vertically above the bottom surface of the upstream oil-mist trapping chamber and is positioned at substantially the same vertical level as the lowermost portion of the bottom surface of the downstream oil-mist trapping chamber.
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This application claims priority to Japanese patent application serial number 2017-236918 filed Dec. 11, 2017, which is hereby incorporated herein by reference in its entirety for all purposes.
BACKGROUNDThe present disclosure relates to an oil separator, and more specifically, it relates to an oil separator to trap oil mist contained in blow-by gas.
A conventional positive crankcase ventilation (PCV) system, which is employed in an internal combustion engine like an automobile engine, is known in the art. Air pollution may result when blow-by gas (un-combusted gas) leaks and/or is discharged from a gap between a piston ring and a cylinder wall of the engine to the exterior atmosphere during operation of the engine. To prevent such leakage of the blow-by gas, the PCV system collects the blow-by gas and then returns the collected blow-by gas to an air intake system. The returned blow-by gas then undergoes re-combustion within the engine. The blow-by gas contains oil mist, which is lubricant oil such as engine oil dispersed as micro particles. The PCV system includes an oil separator designed to trap the oil mist contained in the blow-by gas and prevent the oil mist from flowing into the air intake system. The oil separator is provided in the middle of a flow passage that connects a crankcase and an air-intake duct.
A conventional labyrinth-type oil separator 101, as illustrated in
As illustrated in
Containing more than one oil-mist trapping chambers (the primary oil-mist trapping chamber 151 and the secondary oil-mist trapping chamber 152 in this example), the oil separator provides a passage having a long length for the blow-by gas, which has flown into the oil separator 101. Such a configuration of the oil separator 101, with a long length of passage, can enhance trapping efficiency of the oil mist with a small diameter. The return port 134 allows the oil-mist trapped in the secondary oil-mist trapping chamber 152 to merge with the oil mist trapped in the primary oil-mist trapping chamber 151. The merged, trapped oil may be collected together with the liquid oil trapped in the liquid oil trapping chamber 150. This configuration allows the oil-mist trapped in the secondary oil-mist trapping chamber 152 to be collected without a dedicated collecting passage. As a result, the size of the oil separator 101 may be reduced while the oil separator 101 may efficiently trap and collect the oil mist with a small particle size.
As illustrated in
The blow-by gas, however, may contain a massive amount of the liquid oil with a large particle size. In this case, the liquid oil with a large particle size may flow from the liquid oil trapping passage 150 into the primary oil-mist trapping chamber 151 through the first communication port 132. The liquid oil with a large particle size may subsequently flow through the return port 134 (i.e., shortcut) from the primary oil-mist trapping chamber 151 into the secondary oil-mist trapping chamber 152 without passing through the second communication port 133, and may finally flow out of the oil separator 101 through an outlet port 113 at the lower base 110. As a result, the liquid oil with a large particle size may undesirably flow into an internal combustion engine located downstream of the oil separator 101 and may be combusted, which may cause a failure of the internal combustion engine.
SUMMARYAccording to one aspect of the present disclosure, an oil separator for trapping oil mist contained in blow-by gas includes a separation plate, an upstream oil-mist trapping chamber, and a downstream oil-mist trapping chamber. The upstream and downstream oil-mist trapping chambers are divided by the separation plate and are positioned adjacent to each other. The upstream oil-mist trapping chamber communicates with a flow inlet for blow-by gas. The downstream oil-mist trapping chamber communicates with the upstream oil-mist trapping chamber and a flow outlet for blow-by gas. A return port is configured to return oil mist trapped in the downstream oil-mist trapping chamber back into the upstream oil-mist trapping chamber. The return port is formed through the separation plate. The return port is positioned above the bottom surface of the upstream oil-mist trapping chamber and is positioned at substantially the same vertical level as the lowermost portion of the bottom surface of the downstream oil-mist trapping chamber.
The oil contained in blow-by gas is separated from the blow-by gas and drops in both of the upstream and downstream oil-mist trapping chambers. The oil dropped in the downstream oil-mist trapping chamber is allowed to pass through the return port to the upstream oil-mist trapping chamber. On the other hand, the oil dropped in the upstream oil-mist trapping chamber is prevented from passing through the return port and flowing into the downstream oil-mist trapping chamber. Consequently, the liquid oil gathers in the upstream oil-mist trapping chamber and does not accumulate in the downstream oil-mist trapping chamber. Consequently, the liquid oil is prevented from flowing out of the downstream oil-mist trapping chamber through the flow outlet and subsequently being discharged to the outside. As a result, the liquid oil is prevented from flowing to a device(s) such as an internal combustion engine positioned downstream of the oil separator and from being combusted in the internal combustion engine. In this way, this configuration may prevent a device(s) located downstream of the oil separator from being broken down.
According to another aspect of the present disclosure, the separation plate includes a wall surface facing opposite to the upstream oil-mist trapping chamber. The wall surface may be formed with a rib in the vicinity of the return port. The rib is configured to prevent blow-by gas from flowing into the return port through the return port. Consequently, blow-by gas is prevented from flowing from the upstream oil-mist trapping chamber through the return port into the downstream oil-mist trapping chamber. Thus, the blow-by gas tends not to flow through the return port but through a communication port that communicates the upstream oil-mist trapping chamber with the downstream oil-mist trapping chamber, from the upstream oil-mist trapping chamber to the downstream oil-mist trapping chamber.
According to another aspect of the present disclosure, the rib may have a substantially U-shaped form. For example, the rib may extend along the return port. Therefore, the blow-by gas may be prevented from flowing from the upstream oil-mist trapping chamber through the return port into the downstream oil-mist trapping chamber.
As previously described, in some conventional oil separators, the liquid oil with a large particle size may undesirably flow into an internal combustion engine located downstream of the oil separator and may be combusted. Thus, there has been a need of an oil separator capable of: preventing liquid oil contained in blow-by gas from flowing into a device located downstream of the oil separator, and thereby suppressing a failure of the device even when the blow-by gas contains a massive amount of the liquid oil with a large particle size.
Hereinafter, an exemplary embodiment will be described with reference to
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The lower base 10, the middle base 30, and the upper base 40 illustrated in
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As described above, the oil separator 1 includes a plurality of oil-mist trapping chambers, for example, a primary oil-mist trapping chamber 51 and a secondary oil-mist trapping chamber 52. Therefore, the total length traversed by the blow-by gas passage within the oil separator 1 is relatively long. Such a long length flow passage through the oil separator offers the potential to enhance the efficiency at which the small particle size oil mist contained in the blow-by gas is trapped.
As illustrated in
As described above, the oil separator 1 includes a separation plate 31, an upstream oil-mist trapping chamber (primary oil-mist trapping chamber 51), and a downstream oil-mist trapping chamber (secondary oil-mist trapping chamber 52) as illustrated in
The oil contained in blow-by gas is separated from the blow-by gas by the separator 1, and gathers as droplets in both the upstream oil-mist trapping chamber 51 and the downstream oil-mist trapping chamber 52. The oil that drops and accumulates in the downstream oil-mist trapping chamber 52 passes through the return port 34 and is allowed to return to the upstream oil-mist trapping chamber 51. On the other hand, the oil that drops and accumulates in the upstream oil-mist trapping chamber 51 is not allowed to flow through the return port 34 into the downstream oil-mist trapping chamber 52. Consequently, liquid oil is not accumulated in the downstream oil-mist trapping chamber 52, and as a result, the separated liquid oil is prevented from flowing out of the downstream oil-mist trapping chamber 52 through the flow outlet 13 so as to be discharged outside of the oil separator 1. As a result, the liquid oil can be prevented from flowing to a device(s) such as an internal combustion engine positioned downstream of the oil separator 1 and from being combusted again in the internal combustion engine. In this way, the failure of a device(s) located downstream of the oil separator 1 can be prevented.
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The rib 35 has a substantially U-shape as illustrated in
As described-above, the lower base 10, the middle base 30, and the upper base 40 are made of resin. Alternatively, the lower base 10, the middle base 30, and the upper base 40 may be made of separate metal members that are integrally connected. Such a metal oil separator generally has a higher strength and heat resistance as compared to the resin oil separator 1. As described-above, the lower base 10, the middle base 30, and the upper base 40 are made as separate members. Alternatively, two or all of these bases may be formed in one member.
As described-above, the oil separator 1 has two oil-mist trapping chambers 51, 52. Alternatively, the oil separator 1 may have more than two oil-mist trapping chambers.
The various examples described above in detail with reference to the attached drawings are intended to be representative of the present disclosure and are thus non limiting embodiments. The detailed description is intended to teach a person of skill in the art to make, use and/or practice various aspects of the present teachings and thus does not limit the scope of the disclosure in any manner. Furthermore, each of the additional features and teachings disclosed above may be applied and/or used separately or with other features and teachings in any combination thereof, to provide improved oil separators, and/or methods of making and using the same.
Claims
1. An oil separator for trapping oil mist contained in blow-by gas, the oil separator comprising:
- an upstream oil-mist trapping chamber in fluid communication with a flow inlet for blow-by gas;
- a downstream oil-mist trapping chamber positioned adjacent to the upstream oil-mist trapping chamber and separated from the upstream oil-mist trapping chamber by a separation plate;
- a communication port in fluid communication with the upstream oil-mist trapping chamber and the downstream oil-mist trapping chamber;
- a flow outlet configured to allow blow-by gas from the downstream oil-mist trapping chamber to flow outside of the oil separator; and
- a return port extending through the separation plate and configured to allow oil mist trapped in the downstream oil-mist trapping chamber to return into the upstream oil-mist trapping chamber;
- wherein the return port is positioned above a bottom surface of the upstream oil-mist trapping chamber and is positioned at substantially the same height as a lowermost portion of a bottom surface of the downstream oil-mist trapping chamber.
2. The oil separator of claim 1, wherein the separation plate comprises:
- a wall surface facing opposite to the upstream oil-mist trapping chamber; and
- a rib formed on the wall surface proximal the return port, wherein the rib is configured to prevent blow-by gas from flowing from the upstream oil-mist trapping chamber into the downstream oil-mist trapping chamber through the return port.
3. The oil separator of claim 2, wherein the rib has a U-shape configuration and extends along the return port.
4. The oil separator of claim 2, wherein the rib has a U-shape configuration and extends in an arc shape around the return port.
5. The oil separator of claim 4, wherein the arc extends more than 180 degrees about the return port.
6. An oil separator for trapping oil mist contained in blow-by gas, the oil separator comprising:
- a liquid oil trapping chamber including at least one hole configured to allow liquid oil to exit under the force of gravity;
- an upstream oil-mist trapping chamber in fluid communication with the liquid oil trapping chamber;
- a downstream oil-mist trapping chamber positioned adjacent to the upstream oil-mist trapping chamber and separated from the upstream oil-mist trapping chamber by a separation plate;
- a communication port configured to allow the upstream oil-mist trapping chamber to communicate with the downstream oil-mist trapping chamber;
- a flow outlet configured to allow blow-by gas from the downstream oil-mist trapping chamber to flow outside of the oil separator; and
- a return port formed through the separation plate and configured to allow oil mist trapped in the downstream oil-mist trapping chamber to return into the upstream oil-mist trapping chamber;
- wherein the return port is positioned vertically above a bottom surface of the upstream oil-mist trapping chamber and is positioned at substantially the same vertical level as a lowermost portion of a bottom surface of the downstream oil-mist trapping chamber.
7. An oil separator for trapping oil mist contained in blow-by gas, the oil separator comprising:
- a liquid oil trapping chamber;
- an upstream oil-mist trapping chamber downstream of the liquid oil trapping chamber, wherein the liquid oil trapping chamber is in fluid communication with a flow inlet for blow-by gas from the upstream liquid oil trapping chamber;
- a downstream oil-mist trapping chamber positioned adjacent to the upstream oil-mist trapping chamber and separated from the upstream oil-mist trapping chamber by a separation plate;
- a communication port configured to allow the upstream oil-mist trapping chamber to communicate with the downstream oil-mist trapping chamber;
- a flow outlet configured to allow blow-by gas from the downstream oil-mist trapping chamber to flow outside of the oil separator; and
- a return port formed through the separation plate such that the return port allows oil mist trapped in the downstream oil-mist trapping chamber to return into the upstream oil-mist trapping chamber;
- wherein the return port is located at a level higher than a bottom surface of the upstream oil-mist trapping chamber and is positioned at substantially the same level as a lowermost portion of a bottom surface of the downstream oil-mist trapping chamber.
8. The oil separator of claim 7, wherein the liquid oil trapping chamber includes two holes formed in a bottom portion thereof, wherein the two holes are configured to allow liquid oil to exit the liquid oil trapping chamber under the force of gravity.
9. The oil separator claim 8, wherein the two holes formed in the bottom portion of the liquid oil trapping chamber are laterally spaced apart.
10. The oil separator of claim 9, wherein a first collision wall extends obliquely and upward from proximal a center of the two holes and forms a barrier for large particle size liquid oil contained in blow-by gas, wherein the first collision wall is made of resin material such that the oil adheres thereto.
11. The oil separator of claim 7, wherein the separation plate includes a wall surface facing opposite to the upstream oil-mist trapping chamber and a rib formed on the wall surface proximal the return port such that the rib prevents blow-by gas from flowing from the upstream oil-mist trapping chamber into the downstream oil-mist trapping chamber through the return port.
12. The oil separator of claim 7, wherein the rib has a U-shape configuration and extends about at least a portion of the return port.
13. The oil separator of claim 11, wherein the rib has a U-shape configuration and extends circumferentially in an arc shape around the return port.
14. The oil separator of claim 13, wherein the arc extends angularly more than 180 degrees about the return port.
15. The oil separator of claim 11, wherein the rib is formed in a V-shape configuration.
16. The oil separator of claim 11, wherein the rib is formed in a horseshoe configuration.
17. The oil separator of claim 7, wherein the liquid oil trapping chamber is positioned adjacent to and immediately below the downstream oil-mist trapping chamber.
18. The oil separator of claim 7, wherein the communication port has a square-shaped void configuration.
19. The oil separator of claim 7, wherein the liquid oil trapping chamber is positioned immediately adjacent to the upstream oil-mist trapping chamber.
20. The oil separator of claim 7, wherein the downstream oil-mist trapping chamber is located laterally adjacent to the upstream oil mist trapping chamber, and wherein the downstream oil-mist trapping chamber is located directly above and adjacent to the liquid oil trapping chamber.
Type: Application
Filed: Dec 10, 2018
Publication Date: Jun 13, 2019
Applicants: KOJIMA INDUSTRIES CORPORATION (Toyota-shi), TOYOTA JIDOSHA KABUSHIKI KAISHA (Toyota-shi)
Inventors: Takuya SUZUKI (Toyota-shi), Hirotaka MATSUDA (Toyota-shi), Naoya TAMURA (Toyota-shi), Masami ISHIKAWA (Aichi-gun), Tomoki NAKAMURA (Okazaki-shi)
Application Number: 16/214,263