JP2018145853A - Electrostatic oil mist separator of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow for suppression of connection of condensate water from a cathode to an anode without degrading oil mist capturing performance.SOLUTION: An oil mist separator 10 comprises: an electrostatic capturing part 13 provided with an electrode 40 having a cathode 41 and an anode 42 opposed to each other, and a filter 50 composed of an electrically insulating material and disposed between the cathode 41 and the anode 42 of the electrode 40; a case 12 accommodating the electrostatic capturing part 13; and a voltage generation device 60 applying voltage to the cathode 41 and the anode 42 of the electrode 40. Oil mist included in blowby gas of an internal combustion engine is separated by electrostatic attracting force by making the blowby gas pass through the filter 50 while the voltage generation device 60 applies voltage to between the cathode 41 and the anode 42 of the electrode 40. A cooling device 70 for cooling and condensing water vapor in the case 12 is disposed at a position upstream from the electrostatic capturing part 13 in the case 12 in a flowing direction of the blowby gas.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electrostatic oil mist separator for an internal combustion engine that separates oil mist contained in blow-by gas by electrostatic adsorption force.

  The internal combustion engine is provided with a return passage for returning the blow-by gas in the crank chamber to the intake passage. An oil mist separator that separates oil mist contained in blow-by gas is provided in the middle of such a reflux passage (see, for example, Patent Document 1).

  The oil mist separator described in Patent Document 1 is a static electrode having a plate-like electrode having a positive electrode and a negative electrode facing each other, and a filter interposed between the positive electrode and the negative electrode of the electrode. A collection unit, a case that houses the electrostatic collection unit, and a voltage generator that applies a voltage between the positive electrode and the negative electrode of the electrode are provided.

  In such an oil mist separator, a voltage of, for example, several kV is applied between the positive electrode and the negative electrode of the electrode by the voltage generator, and the filter is charged and the oil mist contained in the blow-by gas passing through the filter is charged. . The charged oil mist is separated from the blow-by gas by being adsorbed to the filter by electrostatic force.

  By the way, since the blow-by gas contains moisture, the moisture may be condensed to generate condensed water. In this case, there is a possibility that the power consumption increases due to the conduction between the electrodes due to the expansion of the condensed water in the filter.

  Therefore, in the oil mist separator described in Patent Document 1, by forming a coating layer made of an insulator on the mutually facing surfaces of the positive electrode and the negative electrode of the electrode, condensed water is prevented from being connected from the positive electrode to the negative electrode of the electrode. I am doing so.

Japanese Patent Laid-Open No. 2006-75154

  However, in the oil mist separator described in Patent Document 1, an insulator such as a coat layer is provided separately from the filter between the positive electrode and the negative electrode of the electrode. Therefore, the electrostatic force is weakened by the insulator, and a contradiction arises that the oil mist collecting performance is impaired.

  An object of the present invention is to provide an electrostatic oil mist separator for an internal combustion engine that can suppress the condensate from being connected from the positive electrode to the negative electrode of the electrode without impairing the oil mist collecting performance.

  An electrostatic oil mist separator for an internal combustion engine for achieving the above object is formed of an electrode having a positive electrode and a negative electrode facing each other, and an electrically insulating material, and is interposed between the positive electrode and the negative electrode of the electrode. An electrostatic collector having a filter, a case for accommodating the electrostatic collector, and a voltage generator for applying a voltage between a positive electrode and a negative electrode of the electrode. By passing the blow-by gas of the internal combustion engine through the filter in a state where a voltage is applied between the positive electrode and the negative electrode of the electrode, oil mist contained in the blow-by gas is separated by electrostatic adsorption force. A cooling device that cools and condenses the water vapor in the case is provided at at least one of the upstream side and the downstream side in the flow direction of the blow-by gas with respect to the electrostatic collection part in the case.

  According to this configuration, when the engine operation is stopped, the water vapor present around the cooling device located in the case is cooled and condensed on the surface of the cooling device. Thereby, the quantity of the water vapor | steam which exists in a case can be reduced, and it can suppress that water vapor | steam is condensed in an electrostatic collection part and condensed water is produced | generated.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that condensed water is connected from the positive electrode of an electrode to a negative electrode, without impairing the collection performance of oil mist.

The perspective view which shows a separator main body about 1st Embodiment of the electrostatic oil mist separator of an internal combustion engine. The figure which shows the cross-section of the separator main body along the 2-2 line | wire of FIG. 3, and the electrical connection aspect of the positive electrode and negative electrode of an electrode, and a voltage generator. Sectional drawing of the separator main body along the 3-3 line of FIG. Sectional drawing corresponding to FIG. 3 about the separator main body of 2nd Embodiment.

<First Embodiment>
The first embodiment will be described below with reference to FIGS.
As shown in FIGS. 1 to 3, the electrostatic oil mist separator (hereinafter referred to as oil mist separator 10) is provided in a recirculation passage for recirculating blow-by gas in a crank chamber of an in-vehicle internal combustion engine to an intake passage. A separator body 11 is provided.

The separator main body 11 has a case 12 formed of an electrically insulating hard resin material.
The case 12 includes a case main body 20 having an upper opening and a lid 30 that closes the upper opening of the case main body 20. The case body 20 includes a side wall 21 that surrounds the upper opening, and a bottom wall 22 that has a rectangular plate shape and faces the lid 30. In the following description, the longitudinal direction and the width direction of the bottom wall 22 are simply referred to as the longitudinal direction and the width direction.

  On the bottom wall 22 on one end side in the longitudinal direction, a cylindrical gas inlet 23 communicating with the inside and outside of the case 12 is provided so as to protrude downward. On the side wall 21 on the other end side in the longitudinal direction, a cylindrical gas outlet 24 that communicates the inside and outside of the case 12 protrudes outward. A cylindrical oil discharge port 25 that communicates the inside and the outside of the case 12 is provided projecting downward at a position near the gas outlet 24 in the bottom wall 22.

An electrostatic collection part 13 is accommodated in the case 12. The electrostatic collector 13 is disposed between the gas inlet 23 and the oil outlet 25 in the longitudinal direction.
As shown in FIGS. 1 and 2, the electrostatic collection portion 13 is formed of a stainless steel plate, and a plurality of (four in the present embodiment) electrodes 40 arranged in parallel with each other, and electrical insulation. The filter 50 is formed of polyester fibers as a material and interposed between the electrodes 40 adjacent to each other. Each electrode 40 is disposed along both the longitudinal direction and the vertical direction. Note that the number of the electrodes 40 may be two or more, and the number of the electrodes 40 can be arbitrarily changed. Each filter 50 is in contact with a pair of electrodes 40 sandwiching the filter 50. An electrically insulating material such as polyester is also a dielectric material in which dielectric polarization occurs.

  As shown in FIG. 2, a voltage generator 60 is electrically connected to each electrode 40 via a conducting wire. The anode (+) of the voltage generator 60 is connected to the even-numbered electrode 40 from the top of the figure. Further, the cathode (-) of the voltage generator 60 is connected to the odd-numbered electrodes 40 from the top of the figure. That is, the electrode 40 has a positive electrode 41 and a negative electrode 42 that face each other. The voltage generator 60 can apply a voltage of several kV between the positive electrode 41 and the negative electrode 42 of the electrode 40.

  As shown in FIGS. 1 to 3, a cooling device 70 that cools and condenses the water vapor in the case 12 is located upstream of the electrostatic collector 13 in the case 12 in the flow direction of the blow-by gas. Is provided.

As shown in FIGS. 1 and 3, the cooling device 70 includes a thermoelectric element 71 and a cooling plate 72 having an L-shaped cross section connected to the thermoelectric element 71.
The cooling plate 72 protrudes into the case 12 through a base 72 a disposed along the upper surface of the lid 30, a bend from one end in the longitudinal direction of the base 72 a and an insertion hole 30 a (see FIG. 3) formed in the lid 30. Projecting portion 72b. The protrusion 72 b is disposed along both the width direction and the up-down direction, and is located immediately above the gas inlet 23. Therefore, a gap is provided between the protruding portion 72 b and the electrostatic collection portion 13.

  The thermoelectric element 71 is a Peltier element having a pair of metal plates 71a and 71b. A cooling side metal plate 71 a is connected to the upper surface of the base portion 72 a of the cooling plate 72. A power supply common to the voltage generator 60 is connected to the pair of metal plates 71a and 71b through conductive wires.

  When the thermoelectric element 71 is energized, the cooling-side metal plate 71a is cooled and the cooling plate 72 connected to the metal plate 71a is cooled. In addition, the electricity supply mode to the thermoelectric element 71 is controlled by an electronic control device (not shown).

  In the present embodiment, the gas inlet 23 through which blow-by gas flows into the case 12 also functions as a condensed water outlet 26 that discharges condensed water condensed by the cooling device 70 to the outside of the case 12.

Next, the operation of this embodiment will be described.
First, the basic operation of the oil mist separator 10 of the present embodiment will be described.
During operation of the internal combustion engine, blow-by gas flows into the case 12 through the gas inlet 23 in a state where a voltage of, for example, several kV is applied between the electrodes 40. At this time, the filter 50 is charged with the application of the voltage, and the oil mist contained in the blow-by gas passing through the filter 50 toward the gas outlet 24 is charged. The charged oil mist is adsorbed to the filter 50 by electrostatic force.

  At this time, when the oil mist contained in the blow-by gas is not charged, positive or negative charges are generated on the surface due to dielectric polarization when passing through the gaps between the fibers of the filter 50. For this reason, the oil mist is attracted to negative or positive charges on the fiber surface of the filter 50 by electrostatic force, and is easily adsorbed by the filter 50.

The adsorbed oil component falls by its own weight and is discharged to the outside through the oil discharge port 25 through the bottom wall 22.
As described above, according to the oil mist separator 10 of the present embodiment, the oil mist can be effectively captured even with the coarse filter 50, and the ventilation resistance of the filter 50 can be reduced.

Next, the characteristic operation of the oil mist separator 10 of the present embodiment will be described.
For example, immediately after the engine operation is stopped, when the protrusion 72b is cooled by energizing the thermoelectric element 71 of the cooling device 70, the water vapor existing around the protrusion 72b is cooled and the protrusion 72b is cooled. Condenses on the surface. Thereby, the quantity of the water vapor | steam which exists in the case 12 can be reduced, and it can suppress that water vapor | steam is condensed in the electrostatic collection part 13, and condensed water is produced | generated.

  As shown in FIG. 3, the condensed water W condensed on the surface of the protrusion 72 b is discharged out of the case 12 through a gas inlet 23 (condensate outlet 26) formed in the bottom wall 22 of the case 12. For this reason, it can suppress that the condensed water W condensed on the surface of the protrusion part 72b moves to the electrostatic collection part 13, and can suppress that the condensed water W stagnates in the electrostatic collection part 13. .

According to the electrostatic oil mist separator of the internal combustion engine according to the present embodiment described above, the following operational effects can be obtained.
(1) A cooling device 70 that cools and condenses water vapor in the case 12 is provided at a position upstream of the electrostatic collector 13 in the case 12 in the flow direction of the blow-by gas.

  According to such a structure, since the said effect | action is show | played, it can suppress that condensed water is connected from the positive electrode 41 of the electrode 40 to the negative electrode 42, without impairing the collection performance of oil mist. Thereby, at the time of the next engine operation, a voltage can be applied between the positive electrode 41 and the negative electrode 42 of the electrode 40 immediately after the engine is started. Therefore, oil mist contained in blow-by gas can be collected effectively.

(2) The bottom wall 22 of the case 12 is formed with a condensed water discharge port 26 for discharging condensed water condensed by the protrusion 72 b of the cooling device 70 to the outside of the case 12.
According to such a structure, since the said effect | action is show | played, it can suppress that the condensed water W stagnates in the electrostatic collection part 13. FIG.

  (3) In the bottom wall 22 of the case 12, the blow-by gas flows into the case 12 at a position upstream of the electrostatic collector 13 in the flow direction of the blow-by gas, and also functions as a condensed water discharge port 26. A gas inlet 23 is formed.

  According to such a configuration, the blow-by gas flows into the case 12 through the gas inlet 23 formed in the bottom wall 22 of the case 12. Further, the condensed water W condensed on the surface of the protrusion 72 b of the cooling device 70 is discharged out of the case 12 through the gas inlet 23 by its own weight. Therefore, the gas inlet 23 and the condensed water outlet 26 can be shared.

  (4) The cooling device 70 includes a thermoelectric element 71 provided outside the case 12, and a protrusion 72 b that is connected to the thermoelectric element 71 and protrudes into the case 12 and is cooled by the thermoelectric element 71.

  According to such a configuration, the protruding portion 72 b can be cooled by energizing the thermoelectric element 71. Moreover, since the protrusion part 72b protrudes in the case 12, it becomes easy for the blowby gas which flows in the case 12 to collide with the protrusion part 72b, and can accelerate | stimulate condensation and isolation | separation of the water vapor | steam contained in blowby gas. . Moreover, since the thermoelectric element 71 is provided outside the case 12, it is possible to appropriately prevent the internal space of the case 12 from being sacrificed by the cooling device 70.

Second Embodiment
With reference to FIG. 4, the second embodiment will be described focusing on differences from the first embodiment.
As shown in FIG. 4, the cooling device 70 is provided downstream of the electrostatic collection unit 13 in the case 12 in the flow direction of the blow-by gas.

  The oil discharge port 25 is open to the bottom wall 22 and protrudes downward, and has a cylindrical enlarged portion 25a. The oil discharge port 25 opens to the bottom wall of the enlarged portion 25a and protrudes downward. And a cylindrical reduced portion 25b having a reduced opening area.

  The protruding portion 72 b is disposed along both the width direction and the up-down direction, and is located immediately above the enlarged portion 25 a of the oil discharge port 25. Therefore, a gap is provided between the protruding portion 72 b and the electrostatic collection portion 13.

  In the present embodiment, the oil discharge port 25 that discharges the oil separated from the blow-by gas to the outside of the case 12 also functions as the condensed water discharge port 26 that discharges the condensed water condensed by the cooling device 70 to the outside of the case 12. To do.

  According to the electrostatic oil mist separator of the internal combustion engine according to the present embodiment described above, the following functions and effects are newly added to the effects (1), (2), and (4) of the first embodiment. It will be obtained.

  (5) The cooling device 70 is provided downstream of the electrostatic collection unit 13 in the case 12 in the flow direction of the blow-by gas. In the bottom wall 22 of the case 12, the oil separated from the blow-by gas is discharged to the outside of the case 12 at a position downstream of the electrostatic collection unit 13 in the flow direction of the blow-by gas and as a condensed water discharge port 26. An oil discharge port 25 that also functions is formed.

  According to such a configuration, the oil separated from the blow-by gas by the electrostatic collector 13 is discharged out of the case 12 through the oil discharge port 25 formed in the bottom wall 22 of the case 12. Further, the condensed water W condensed on the surface of the protrusion 72b of the cooling device 70 is discharged outside the case 12 through the oil discharge port 25 by its own weight. Therefore, the oil discharge port 25 and the condensed water discharge port 26 can be shared.

<Modification>
In addition, the said embodiment can also be changed as follows, for example.
-The protrusion part 72b can also be arrange | positioned along both the longitudinal direction and the width direction. In this case, an insertion hole through which the protruding portion 72 b is inserted may be formed in the side wall 21 of the case 12.

-You may make it provide multiple protrusion part 72b.
A water repellent process may be applied to the surface of the protrusion 72 b of the cooling plate 72. Thereby, the condensed water W condensed on the surface of the protrusion part 72b becomes easy to fall.

-You may make the protrusion part of a cooling plate into mesh shape. Moreover, you may make the protrusion part of a cooling plate into the shape which has many fins like a heat sink.
The cooling device is not limited to the one having the thermoelectric element 71. In addition, for example, a pipe through which a cooling medium flows may be provided.

  DESCRIPTION OF SYMBOLS 10 ... Oil mist separator, 11 ... Separator main body, 12 ... Case, 13 ... Electrostatic collection part, 20 ... Case main body, 21 ... Side wall, 22 ... Bottom wall, 23 ... Gas inflow port, 24 ... Gas outflow port, 25 DESCRIPTION OF SYMBOLS Oil discharge port, 25a ... Expansion part, 25b ... Reduction part, 26 ... Condensate discharge port, 30 ... Lid, 30a ... Insertion hole, 40 ... Electrode, 41 ... Positive electrode, 42 ... Negative electrode, 50 ... Filter, 60 ... Voltage Generating device, 70 ... cooling device, 71 ... thermoelectric element, 71a, 71b ... metal plate, 72 ... cooling plate, 72a ... base, 72b ... projection.

Claims (5)

An electrode having a positive electrode and a negative electrode facing each other, and an electrostatic collector formed of an electrically insulating material and having a filter interposed between the positive electrode and the negative electrode of the electrode;
A case for accommodating the electrostatic collector;
A voltage generator for applying a voltage between a positive electrode and a negative electrode of the electrode,
By passing the blow-by gas of the internal combustion engine through the filter in a state where a voltage is applied between the positive electrode and the negative electrode of the electrode by the voltage generator, oil mist contained in the blow-by gas is absorbed by electrostatic adsorption force. An oil mist separator for an internal combustion engine to be separated,
A cooling device that cools and condenses water vapor in the case is provided at at least one position on the upstream side and downstream side in the flow direction of the blow-by gas from the electrostatic collection part in the case.
Electrostatic oil mist separator for internal combustion engines. The bottom wall of the case is formed with a condensed water discharge port for discharging condensed water condensed by the cooling device to the outside of the case.
The electrostatic oil mist separator for an internal combustion engine according to claim 1. The cooling device is provided on the upstream side in the flow direction of the blow-by gas from the electrostatic collection part in the case,
A gas inlet that allows blow-by gas to flow into the case and also functions as the condensed water discharge port at a position upstream of the electrostatic collector in the flow direction of the blow-by gas in the bottom wall of the case Is formed,
The electrostatic oil mist separator for an internal combustion engine according to claim 2. The cooling device is provided on the downstream side in the flow direction of blow-by gas from the electrostatic collection part in the case,
In the bottom wall of the case, the oil separated from the blow-by gas is discharged to the position downstream of the electrostatic collection part in the flow direction of the blow-by gas, and also used as the condensed water discharge port. A functioning oil outlet is formed,
The electrostatic oil mist separator for an internal combustion engine according to claim 2 or 3. The cooling device includes a thermoelectric element provided outside the case, and a protrusion connected to the thermoelectric element and protruding into the case and cooled by the thermoelectric element.
The electrostatic oil mist separator for an internal combustion engine according to any one of claims 1 to 4.

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