JP6520602B2 - Oil separator - Google Patents

Description

  The present invention relates to an oil separator which introduces blow-by gas of an internal combustion engine into a case to separate it from oil and discharges the separated oil to the outside of the case.

  The internal combustion engine is provided with a return passage for returning blowby gas in the crank chamber to the intake passage. In addition, an oil separator is provided in the middle of the reflux passage to separate misty oil contained in the blowby gas (see, for example, Patent Document 1).

  In the case of the oil separator described in Patent Document 1, two mesh-like electrodes are disposed to face each other, and a potential difference is given to these electrodes by a power supply device. According to such an oil separator, when the blowby gas passes through one of the electrodes, the water contained in the blowby gas is charged, and the charged water is adsorbed to the other electrode by electrostatic force. At this time, the misty oil contained in the blowby gas is adsorbed to the electrode together with the water. Thus, it is supposed that the misty oil contained in the blowby gas can be separated. The oil and moisture adsorbed by the electrode fall by their own weight, and are discharged out of the case through the oil outlet formed on the bottom wall of the case.

Unexamined-Japanese-Patent No. 3-141811

  By the way, in the oil separator described in Patent Document 1, when the flow velocity of the blowby gas is large, the oil easily passes through the electrode without colliding with the electrode. Therefore, the oil capture efficiency is low.

  On the other hand, in the oil separator, it is conceivable to make the oil more likely to collide with the electrode by making the mesh of the electrode finer. However, in this case, the fine mesh of the electrode increases the air flow resistance, and causes another problem such as an increase in pressure loss due to the oil separator.

  An object of the present invention is to provide an oil separator capable of appropriately improving the oil capture efficiency.

  An oil separator for achieving the above object introduces blow-by gas of an internal combustion engine into a case to separate it from oil, and discharges the separated oil to the outside of the case. Inside the case, a plurality of electrode plates are disposed to face each other at an interval, and a filter made of an electrically insulating material is interposed between each of the electrode plates, and a potential difference is applied. The filter has a high density portion at a central portion in the opposing direction of the adjacent electrode plates in the filter, and a high density portion whose density is higher than that in the opposing direction of the adjacent electrode plates in the filter.

  According to the same configuration, a filter is interposed between the electrode plates, and an electric potential is generated between the electrode plates by applying a potential difference between the electrode plates, and positive or negative on the surface of the filter due to dielectric polarization. Charge is generated. For this reason, the charged oil among the misty oil contained in the blow-by gas is bent in the moving direction by the electrostatic force when passing between the electrode plates, and is easily captured by the filter.

  Further, among the misty oil contained in the blowby gas, positive or negative charges are generated on the surface of the oil due to dielectric polarization when passing through a filter interposed between the electrode plates. For this reason, the oil is attracted to the negative or positive charge on the surface of the filter by the electrostatic force, and is easily captured by the filter.

  As described above, according to the above configuration, the oil can be efficiently captured even with a coarse filter, and an increase in ventilation resistance due to the filter can be suppressed. Therefore, while being able to suppress the increase in pressure loss, the capture efficiency of oil can be improved.

  By the way, if the density of the filter interposed between the adjacent electrode plates is uniform, the flow velocity of the blowby gas passing through the filter becomes higher toward the central portion in the opposing direction of the adjacent electrode plates in the filter. The flow rate of the blowby gas increases as the flow velocity of the blowby gas increases in the filter. However, the oil capture efficiency decreases as the flow velocity of the blowby gas increases. Therefore, if the density of the filter is uniform, the oil contained in the blowby gas is trapped by the filter at the central portion in the opposite direction of the adjacent electrode plates in the filter, despite the high flow rate of the blowby gas passing therethrough. There is a risk that the same filter will often be passed.

  In this respect, according to the above-described configuration, the central portion in the opposing direction of the adjacent electrode plates in the filter is provided with a high density portion having a density higher than that of both end portions in the opposing direction of the adjacent electrode plates in the filter . Therefore, as compared with the case where the density of the filter is uniform, the flow rate of the blowby gas flowing in the portions on both ends in the opposing direction of the adjacent electrode plates in the filter is increased. And since the flow velocity of blow-by gas becomes relatively small in the center part of the opposing direction of the adjacent electrode plate in a filter, the flow velocity distribution of blow-by gas approaches a uniform state. Therefore, it can suppress that the flow velocity of blow-by gas becomes relatively large in the center part of the opposing direction of the adjacent electrode plate in a filter, and can reduce the oil which passes through the filter without being caught by the filter. .

  In addition, the filter has a high density part at the central part in the opposing direction of the adjacent electrode plates in the same filter, so that parts on both sides of the high density part in the filter, that is, parts between the high density part in the filter and the electrode plate The flow rate of the blowby gas flowing in a portion closer to the electrode plate than the high density portion is increased. Therefore, more of the misty oil contained in the blowby gas can be attracted to the electrode plate.

  According to the present invention, the oil capture efficiency can be appropriately improved.

The perspective view of the oil separator which concerns on embodiment. The top view in the state where the lid of the above-mentioned oil separator was removed. The top view of the adjacent electrode plate in the said oil separator, and the filter interposed therebetween. The schematic diagram explaining the effect | action of the said oil separator. Explanatory drawing which compares the oil trapping efficiency of the said oil separator, and the oil trapping efficiency of the oil separator provided with the filter with uniform density.

Hereinafter, an embodiment of the oil separator will be described with reference to FIGS. 1 to 5.
As shown in FIG. 1, the oil separator 10 is provided in a reflux passage for recirculating blowby gas in a crank chamber of an internal combustion engine to an intake passage, and is formed of an electrically insulating hard resin material such as nylon 66, for example. Case 11 is included.

  The case 11 has a case main body 20 having an upper opening, and a lid 30 provided so as to be able to open and close the upper opening of the case main body 20. The case body 20 has a bottom wall 22 having a rectangular shape in a plan view, and side walls 21 extending upward from four sides of the bottom wall 22.

  As shown in FIGS. 1 and 2, a cylindrical gas inlet 23 is provided on the side wall 21 at one end side in the longitudinal direction of the case main body 20 so as to protrude outward. A cylindrical gas outlet 24 is provided on the side wall 21 on the other end side in the longitudinal direction of the case main body 20 so as to protrude outward. At a position close to the gas outlet 24 in the bottom wall 22, an oil outlet 25 is protruded downward.

  Inside the case main body 20, four electrode plates 40 formed of stainless steel are arranged in the longitudinal direction, that is, the flow direction of the blowby gas and the up and down direction, and are opposed to each other at an interval. Further, adjacent electrode plates 40 are arranged in parallel with each other. Each electrode plate 40 is disposed at a distance from side walls 21 at both ends in the longitudinal direction. The number of electrode plates 40 may be two or more, and can be changed to any number.

  As shown in FIG. 2, a power supply device 60 is electrically connected to each electrode plate 40 via a lead. The anode (+) of the power supply device 60 is connected to the odd-numbered electrode plate 40 from the top of the figure, and the cathode (-) or the earth of the power supply device 60 is connected to the even-numbered electrode plate 40 from the top . As a result, a predetermined potential difference is applied between the electrode plates 40 adjacent to each other by the power supply device 60. In FIG. 1, the power supply device 60 is not shown.

  A filter 50 formed of an electrically insulating material is interposed between the electrode plates 40. The filter 50 is in contact with the adjacent electrode plates 40. Further, the length in the vertical direction and the longitudinal direction of the filter 50 is the same as that of the electrode plate 40, and the arrangement position of each filter 50 in the longitudinal direction corresponds to the arrangement position of each electrode plate 40.

  As shown in FIG. 3, the filter 50 includes a high density portion 52 positioned at the center of the opposing direction (see arrow Y in FIG. 3) of the adjacent electrode plates 40 in the filter 50 and an adjacent high density portion 52. It is comprised from the low density part 53 provided in the both sides of the opposing direction of the electrode plate 40, respectively. The high density portion 52 is formed to have a higher density (that is, a higher filling rate) than the low density portion 53. Therefore, the central portion in the opposing direction of the adjacent electrode plates 40 in the filter 50 has a higher density than the opposite end portions in the opposing direction of the adjacent electrode plates 40 in the filter 50.

  Each of the high density portion 52 and the low density portion 53 is formed of fibers 51 (see FIG. 4) of polyester which is an electrically insulating material. An electrically insulating material such as polyester is also a dielectric material that causes dielectric polarization. For example, the high density portion 52 is formed of a polyester non-woven fabric having a filling rate of 0.086, and the low density portion 53 is formed of a polyester non-woven fabric having a filling rate of 0.023. The packing ratio of the filter 50 is the ratio of the volume of the fibers 51 to the volume of the filter 50 (including the space between the fibers 51). Since little electricity flows in the filter 50 itself formed of such an electrically insulating material, the occurrence of energization between the electrode plates 40 via the moisture trapped in the filter 50 is suppressed.

  Further, the thickness T1 in the opposing direction of the adjacent electrode plates 40 in the high density portion 52 is smaller than the thickness T2 in the opposing direction of the adjacent electrode plates 40 in the low density portion 53. For example, when the distance D between the adjacent electrode plates 40 is 10 mm, the thickness T1 of the high density portion 52 is set to 0.6 mm, and the thickness T2 of each low density portion 53 is set to 4.7 mm. Further, in the present embodiment, one high density part 52 and two low density parts 53 which are separately formed are overlapped and disposed as the filter 50 between the adjacent electrode plates 40.

Next, the operation of the present embodiment will be described.
The blowby gas introduced into the case 11 through the gas inlet 23 moves toward the gas outlet 24.

  In the oil separator 10, a filter 50 is interposed between the electrode plates 40, and a predetermined potential difference is applied between the electrode plates 40, as shown in FIG. An electrostatic field is generated between them, and a positive (+) or negative (-) charge is generated on the surface of the fiber 51 of the filter 50 by dielectric polarization. For this reason, the charged oil among the misty oil contained in the blowby gas is bent in the moving direction by the electrostatic force when passing between the electrode plates 40, and is easily captured by the filter 50. .

  Further, among the misty oil contained in the blowby gas, one which is not charged passes through the gap between the fibers 51 of the filter 50 interposed between the electrode plates 40 as shown in FIG. At the same time, due to dielectric polarization, positive (+) or negative (-) charges are generated on the surface of the oil. For this reason, the oil is attracted to the negative (−) or positive (+) charge on the surface of the fiber 51 of the filter 50 by the electrostatic force, and the oil is easily captured by the filter 50.

  As described above, according to the oil separator 10 of the present embodiment, the oil can be effectively captured even with the coarse filter 50, and an increase in air flow resistance due to the filter 50 can be suppressed. Therefore, while being able to suppress the increase in pressure loss, the capture efficiency of oil can be improved.

  The blowby gas from which the oil is separated flows out to the blowby gas reflux passage through the gas outlet 24. On the other hand, oil and the like accumulated on the bottom wall 22 move along the bottom wall 22 and are discharged to the outside of the case 11 through the oil discharge port 25.

  By the way, when the density of the filter interposed between the adjacent electrode plates 40 is uniform, the flow velocity of the blowby gas passing through the filter becomes larger toward the central portion in the opposing direction of the adjacent electrode plates 40 in the filter. The flow rate of the blowby gas increases as the flow velocity of the blowby gas increases in the filter. However, the oil capture efficiency decreases as the flow velocity of the blowby gas increases. Therefore, even if the density of the filter is uniform, the oil contained in the blowby gas is trapped by the filter in the central portion of the filter in the opposing direction of the adjacent electrode plates 40 despite the high flow rate of the blowby gas passing therethrough. There is a risk that the same filter will often pass without being

  In this respect, according to the oil separator 10 of the present embodiment, the central portion of the filter 50 in the opposing direction of the adjacent electrode plates 40 has a density higher than that of both ends in the opposing direction of the adjacent electrode plates 40 of the filter 50. A high density portion 52 is provided. Therefore, as compared with the case where the density of the filter 50 is uniform, the flow rate of the blow-by gas flowing in the portion (that is, the low density portion 53) of both ends in the opposing direction of the adjacent electrode plates 40 in the filter 50 is increased. And since the flow velocity of blow-by gas becomes relatively small in the central part of the opposing direction of the adjacent electrode plate 40 in the filter 50, the flow velocity distribution of blow-by gas approaches a uniform state. Therefore, it is suppressed that the flow velocity of blow-by gas becomes relatively large at the central portion in the opposing direction of the adjacent electrode plates 40 in the filter 50, and the oil passing through the filter 50 without being captured by the filter 50 is reduced. It can be done.

  Further, the filter 50 has the high density portion 52 at the central portion in the opposing direction of the adjacent electrode plates 40 in the filter 50, whereby the low density portion 53 on both sides of the high density portion 52 in the filter, ie, the high density in the filter 50 The flow rate of the blowby gas flowing in a portion between the portion 52 and the electrode plate 40 and closer to the electrode plate 40 than the high density portion 52 is increased. Therefore, more charged oil among the misty oil contained in the blowby gas can be attracted to the electrode plate 40.

  Here, FIG. 5 shows two types of oil separators of an oil separator with a particle diameter of 0.5 μm and an oil separator with a filter having a uniform density and an oil separator 10 with a filter 50 having a high density part 52. The result of having measured capture efficiency is shown. In FIG. 5, A is the oil capture efficiency of an oil separator provided with a filter having a filling rate of 0.23 and a density (filling rate) with a uniform thickness of 10 mm in the opposing direction of adjacent electrode plates 40. B was composed of a high density part 52 with a filling factor of 0.086 and a thickness T1 of 0.6 mm, and two low density parts 53 with a filling factor of 0.023 and a thickness T2 of 4.7 mm. It is an oil capture efficiency of the oil separator 10 provided with the filter 50 (see FIG. 3). In addition, the measurement of the capture efficiency of the oil in two types of oil separators was performed on the conditions other than the structure of a filter on the same conditions.

  As shown in FIG. 5, the oil separator 10 (B) provided with the filter 50 having the high density portion 52 has an oil capture efficiency of 4.5% as compared with the oil separator (A) provided with the filter having a uniform density. It has been confirmed to improve. Further, the pressure loss of the oil separator (A) provided with the filter with uniform density and the pressure loss of the oil separator 10 (B) provided with the filter 50 having the high density portion 52 were substantially the same.

According to the oil separator according to the present embodiment described above, the following effects can be obtained.
(1) Inside the case 11 of the oil separator 10, a plurality of electrode plates 40 are disposed opposite to each other at an interval. A filter 50 made of an electrically insulating material is interposed between the electrode plates 40, and it is possible to apply a potential difference. In addition, the filter 50 has a high density portion 52 at a central portion in the opposing direction of the adjacent electrode plates 40 in the filter 50, and a high density portion 52 higher in density than both ends in the opposing direction of the adjacent electrode plates 40 in the filter 50. According to such a configuration, since the above-described action is exhibited, the oil capture efficiency can be appropriately improved.

(2) The filter 50 is composed of three layers of the high density part 52 and the pair of low density parts 53, so the configuration is simple. Therefore, the filter 50 can be easily formed.
(3) The high density portion 52 and the low density portion 53 having different densities (filling rates) are separately formed. Therefore, the manufacture of the filter 50 is easy. Further, even when the high density portion 52 and the low density portion 53 are formed of different materials, the filter 50 can be easily formed.

  (4) In each filter 50, the thickness T1 in the opposing direction of the adjacent electrode plates 40 in the high density portion 52 is smaller than the thickness T2 in the opposing direction of the adjacent electrode plates 40 in the low density portion 53. Therefore, an increase in pressure loss due to the provision of the high density portion 52 in the filter 50 can be suppressed. Further, since the flow rate of the blowby gas flowing through the low density portion 53 adjacent to the electrode plate 40 can be increased, more charged oil among the misty oil contained in the blowby gas may be attracted to the electrode plate 40. become able to. Therefore, the oil capture efficiency can be appropriately improved.

The above embodiment may be modified as follows.
The filter 50 may be made of a single non-woven fabric in which the high density portion 52 and the pair of low density portions 53 are integrally formed. In this way, the filter 50 can be easily handled when the oil separator 10 is assembled, and therefore, the filter 50 can be easily disposed between the plurality of electrode plates 40.

  The fibers 51 constituting the filter 50 are not limited to those formed of polyester. In addition, for example, polyethylene, polystyrene, polytetrafluoroethylene or the like having the same electrical resistivity and relative permittivity as polyester can be used. Also, the fibers 51 may be formed of a resin material having electrical insulation such as polyester mixed with a high dielectric material such as titanium oxide.

  The high density portion 52 is not limited to the one formed by the fibers 51 of resin. The high density portion 52 may be, for example, a porous one made of polyurethane or the like. Further, the high density portion 52 may be a plate made of a resin material, a metal material or the like which is a dielectric having electrical insulation. In this case, the high density portion 52 is preferably formed to include a high dielectric material such as barium titanate or titanium dioxide.

The low density portion 53 is not limited to one formed by the resin fibers 51. In addition, for example, it may be a porous one formed of polyurethane or the like.
The density (filling ratio) of the high density portion 52 and the low density portion 53 is not limited to the value of the above embodiment, and is appropriately changed so that the high density portion 52 has a higher value than the low density portion 53. It is also good.

The thickness T1 of the high density portion 52 and the thickness T2 of the low density portion 53 are not limited to the values in the above embodiment, and may be changed as appropriate.
The filter 50 may be formed to have a density gradient in which the density increases toward the central portion of the filter 50 in the opposing direction of the adjacent electrode plates 40.

The distance D in the opposing direction of the adjacent electrode plates 40 can be longer than 10 mm, or can be shorter than 10 mm.
The electrode plate 40 can also be formed by punching metal or metal mesh.

The electrode plate 40 can also be formed of a metal material other than stainless steel.
-At least one of the gas inlet 23 and the gas outlet 24 may be formed in the lid 30.

  DESCRIPTION OF SYMBOLS 10 ... Oil separator, 11 ... Case, 40 ... Electrode plate, 50 ... Filter, 52 ... High density part, 53 ... Low density part.

Claims (4)

In an oil separator which introduces blow-by gas of an internal combustion engine into a case to separate it from oil and discharges the separated oil to the outside of the case,
Inside the case, a plurality of electrode plates are arranged opposite to each other at an interval,
A filter made of an electrically insulating material is interposed between each of the electrode plates, and it is possible to apply a potential difference.
The filter has a high density portion having a higher density than both end portions in the opposing direction of the adjacent electrode plates in the filter at a central portion in the opposing direction of the adjacent electrode plates in the filter.
Oil separator. The filter includes the high density portion, and a pair of low density portions provided on both sides of the high density portion in the opposing direction of the adjacent electrode plates and having a density lower than that of the high density portion.
The oil separator according to claim 1. The high density part and the low density part are formed separately.
The oil separator according to claim 2. The filter is made of one non-woven fabric having the high density portion and the pair of low density portions.
The oil separator according to claim 2.

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