JP2003010605A - Method and apparatus for removing gas mixed in oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently remove a gas mixed in an oil in a short time by simple steps and simple constitutions. SOLUTION: A removal apparatus 10 is provided with a closed container 16 in which an oil 12 is enclosed and a stirring mechanism 18 immersed in the oil 12 in the closed container 16. A rotary shaft 44 composing the stirring mechanism 18 is rotated and, under rotating operation of stirring blades 50a, 50b and 50c attached to the rotary shaft 44, the oil 12 is forcibly stirred and fluidized to receive impact, and consequently, the gas mixed in the oil 12 can be separated and removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for removing gas mixed in oil for separating and removing gas mixed in oil such as lubricating oil from the oil.

[0002]

2. Description of the Related Art Generally, gas (air, etc.) is visually confirmed in oils used as brake fluids, cooling fluids, power steering oils for automobiles, and lubricating oils for four-wheel drive systems. In many cases, they are mixed in the form of fine bubbles that cannot be used. Although there are some differences due to the type and viscosity of the oil, under normal atmospheric pressure conditions, the air mixed in the oil is dissolved by the saturation amount, and the volume ratio is approximately 5%. It is known that about 10% to 10% is dissolved.

As described above, the air mixed in the oil contains oxygen, and this oxygen promotes the chain reaction of the oxidative deterioration reaction to shorten the oil life. Furthermore, since the bubble volume is compressed or expanded due to the load change of the bubbled air, in a hydraulic system or the like, drive control is hindered due to drive delay or the like, and sufficient functions are exhibited for functional parts. Not possible, or
It causes a decline in function. Therefore, it is desired to use the oil in a state where almost all the air mixed in the oil is degassed.

Therefore, for example, in Japanese Utility Model Laid-Open No. 58-17420.
As disclosed in Japanese Patent Publication No. 4 (hereinafter referred to as Prior Art 1), the oil is indirectly heated by hot water of 60 ° C. to 70 ° C., and at the same time, the rotating shaft disposed in the oil is rotated. There is known a device for discharging water and bubbles mixed in the oil.

Further, as disclosed in Japanese Utility Model Laid-Open No. 61-53399 (hereinafter referred to as "prior art 2"), a liquid inflow pipe having a solenoid valve for adjusting an inflow amount is penetrated through a side wall of the tank to form a tank. Consists of a pan extending to the center, opening the end opening upward, and a pan below the end opening, and an outflow pipe provided at the bottom of the tank for letting the processing liquid out of the tank. Known deaeration tanks are known.

Furthermore, as disclosed in Japanese Utility Model Application Laid-Open No. 2-86603 (hereinafter referred to as prior art 3),
A viscous liquid deaerator including a deaeration tank containing a viscous liquid, a vacuum pump connected to the upper part of the deaeration tank, and an ultrasonic vibration generator arranged at the bottom of the deaeration tank is known. (Hereinafter, referred to as Prior Art 3).

[0007]

However, in the above-mentioned conventional technique 1, the deaeration process by heating the oil is mainly used. For this reason, although the deaeration time, which was conventionally required to be 30 to 40 hours, is shortened, the deaeration time of 2 to 3 hours is required, and in practice, the efficiency of the deaeration process should be improved. There is a problem that you can not. Moreover, it has been pointed out that a special structure is required to heat the oil, the equipment becomes large and the equipment cost rises.

Further, in the above-mentioned conventional technique 2, since the tray is arranged in the tank, the size of the apparatus is increased, and it takes a lot of time to deaerate the oil.

Furthermore, in the above-mentioned prior art 3, the use of the ultrasonic vibration generator causes an increase in the size of the device, and there is a possibility that the deaeration process from the oil may not be performed reliably.

The present invention is intended to solve this type of problem, and it is possible to reliably remove the gas mixed in the oil in a short time and to simplify the process and structure. An object of the present invention is to provide a method and an apparatus for removing a mixed gas.

[0011]

In the method and apparatus for removing mixed gas in oil according to the present invention, oil such as lubricating oil is enclosed in a hermetically sealed container, and the hermetically sealed container is depressurized, The oil is forcibly agitated and fluidized under the action of a stirring mechanism immersed in the oil in the sealed container. Therefore, it is possible to give a shock to the entire oil in the sealed container,
The gas mixed in the oil is reliably separated and removed. As a result, the gas mixed in the oil can be reliably removed in a short time with a simple process and configuration.

Further, a plurality of obstacle members are inserted in the sealed container, and the obstacle members are agitated and flow together with oil under the action of the agitating mechanism. Therefore, it is possible to apply an impact to the oil via the obstacle member, and the gas mixed in the oil is separated and removed more quickly and surely. Here, the obstacle member includes a small object having a spherical shape or a rectangular parallelepiped shape,
The manufacturing cost of the obstacle member does not soar, and it is economical.

Further, the hermetically sealed container has an uneven shape on the inner wall,
It has a wavy or polygonal stirring surface. For this reason, it becomes possible to more effectively stir the oil in the sealed container, and the separation and removal of the gas can be smoothly performed.

Furthermore, the stirring mechanism includes a rotor blade, a blade,
A screw or a water wheel is provided, and a depressurized space is formed in the central portion of the sealed container under the rotating action of the stirring mechanism. As a result, the area of the oil surface is increased via the depressurized space, and the gas in the oil is easily and reliably separated and removed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic structural explanatory view of a removing apparatus 10 for carrying out a method for removing a mixed gas in oil according to a first embodiment of the present invention.

The removing device 10 stores an oil, in particular, an oil storage tank 14 in which an oil 12, which is a lubricating oil to be filled in a four-wheel drive device, is stored, and the oil 12 is supplied from the oil storage tank 14 to supply the oil. Sealed container 1 in which oil 12 is enclosed
6 and a stirring mechanism 1 which is immersed in the oil 12 in the hermetically sealed container 16 and forcibly stirs and flows the oil 12.
8, a vacuum pump 24 communicating with the chamber 20 in the hermetically sealed container 16 via a pipe line 22, a negative pressure gauge 26 for measuring the vacuum pressure by the vacuum pump 24, and the vacuum pipe 24 provided in the pipe line 22. And a filter 28.

As shown in FIG. 2, the hermetically sealed container 16 is provided with a cylindrical body 30 made of transparent acrylic, and a disk-shaped lower cover member 32 is arranged on the lower side of the cylindrical body 30.
A disc-shaped upper cover member 34 is disposed on the upper portion of the cylindrical body 30. Lower cover member 32 and upper cover member 34
Has ring-shaped grooves 36a and 36b formed therein, and the grooves 36a and 36b have seal rings 38a and 36a.
The upper and lower ends of the cylindrical body 30 are inserted with 38b interposed.

A plurality of tightening bolts 40 are provided from the upper cover member 34 to the lower cover member 32, and the upper cover member 34, the lower cover member 32 and the cylindrical body 30 are integrated under the tightening action of the tightening bolts 40. Be assembled in a proper manner.

The stirring mechanism 18 includes a chamber 20 inside the sealed container 16.
The lower end of the rotary shaft 44 that constitutes the stirring mechanism 18 is pivotally supported by the lower cover member 32 via a bearing 46a. A large diameter portion 44 is provided on the upper side of the rotary shaft 44.
a is provided, the large diameter portion 44a is rotatably supported by the upper cover member 34 via bearings 46b and 46c, and an end portion of the large diameter portion 44a is connected to a rotary drive source 48. The connecting portion 44b is integrally provided.

On the lower side of the rotary shaft 44, one or more, for example, three stirring blades 50a, 50b and 50c are integrally provided (see FIG. 3). This stirring blade 50
a, 50b and 50c may be twisted, and
Instead of the stirring blades 50a, 50b and 50c,
A rotary blade, a screw or a water wheel may be used.

The lower cover member 32 includes an oil storage tank 14
A first coupler 54 for attaching / detaching the conduit 52 communicating with the pipe is provided, while a second coupler 56 for attaching / detaching the conduit 22 is provided on the upper cover member 34 (see FIG. 2).
The couplers 54 and 56 have check valves 57a and 57, respectively.
b is provided, and the oil storage tank 14 and the sealed container 16 are provided.
And are configured to be shut off.

The operation of the removing apparatus 10 thus constructed will be described below.

As shown in FIG. 1, the conduit 52 is connected to the first coupler 54 of the hermetic container 16 and the conduit 22 is connected to the second coupler 56, and the hermetic container 16 is connected via the vacuum pump 24. The inside chamber 20 is evacuated. Therefore, the oil 12 stored in the oil storage tank 14 is
Is supplied to the chamber 20 in the sealed container 16 via a pipe line 52,
After the oil 12 is filled with a predetermined amount, the pipe line 52 is removed from the first coupler 54. The upper cover member 34 may be temporarily removed and the cylindrical body 30 may be filled with the oil 12 without using the oil storage tank 14.

Then, under the action of the vacuum pump 24, the inside of the chamber 20 is evacuated until the negative pressure gauge 26 displays -100 Kpa. After the negative pressure gauge 26 displays −100 Kpa, the rotary drive source 48 constituting the stirring mechanism 18 is driven, and the rotary shaft 44 connected to the rotary drive source 48 starts rotating in a predetermined direction. Therefore, the sealed container 16
The stirring blades 50a, 50b, and 50c immersed in the oil 12 filled therein are rotated integrally with the rotating shaft 44 to forcibly stir and flow the oil 12.

Therefore, the oil 12 has a stirring blade 50.
The gas (air) mixed in the oil 12, which is given an impact due to contact or collision with a, 50b and 50c, is
The bubbles are forcibly formed, and the bubbles 58 are reliably separated and removed from the oil 12 (see FIG. 4).

As a result, in the first embodiment, it is possible to reliably remove the gas mixed in the oil 12 in a short time with a simple process and configuration. Moreover, the stirring blade 5 that constitutes the stirring mechanism 18
Due to the centrifugal force caused by the rotation of 0a, 50b, and 50c, a depressurized space 60 is formed in the central portion of the sealed container 16 as shown in FIG. For this reason, the surface area of the oil 12 in the sealed container 16 is increased, and the gas mixed in the central portion side in the sealed container 16 becomes the bubbles 5
As a result, the oil 8 is easily removed from the oil 12, and the gas separation and removal process in the oil 12 can be performed more easily and reliably.

Then, as described above, when the stirring mechanism 18 is driven and the bubbles 58 are not generated from the oil 12 filled in the sealed container 16, the bubble removing process in the oil 12 is performed. Complete.

As described above, in the first embodiment, under the action of the stirring mechanism 18 immersed in the oil 12, the oil 12 is agitated and fluidized to give a shock to the oil 12, and the oil 12 is agitated. The gas mixed therein is separated and removed as bubbles 58, and a decompression space 60 is formed in the central portion of the hermetically sealed container 16 to expand the vacuum degassing region from the surface of the oil 12. As a result, the work of removing the gas in the oil 12 was carried out quickly and surely, and for example, when the oil 12 was about 3 liters (liters), the result that the bubble removing process was completed in 4 minutes was obtained. .

In the first embodiment, the stirring mechanism 18
Immediately after the start of driving, the gas mixed in the oil 12 may vigorously foam and overflow. For this reason, the rotary drive source 48 is set until the foaming of the gas is stopped.
After once stopped for a predetermined time, the rotary drive source 48
It is desirable to control so as to restart the driving of.

On the other hand, in the initial stage of stirring, the rotary drive source 4
8 may be driven at a low rotation speed, and the rotation drive source 48 may be controlled to gradually shift to a high rotation speed in accordance with the degree of foaming disappearance of the gas in the oil 12. As a result, the effect of smoothly performing the gas separation and removal operation in the oil 12 can be obtained.

In this case, after the gas in the oil 12 is almost completely removed in the final stage, in order to remove the bubbles 58 attached to the back side of the stirring blades 50a, 50b and 50c,
It is necessary to rotate the rotary shaft 44 intermittently or for a certain period of time to forcibly separate the bubbles 58.

Further, in the first embodiment, the rotary drive source 4
The rotation shaft 44 is rotated in one direction through the oil 12
The air bubbles 58 mixed in the inside are separated and removed,
The rotation direction of the rotary shaft 44 may be reversed at regular intervals. This has the advantage that a greater impact can be applied to the oil 12 and the separation and removal processing of the bubbles 58 in the oil 12 can be effectively performed.

FIG. 5 is a cross-sectional explanatory view of the essential parts of a device 70 for removing a mixed gas in oil according to a second embodiment of the present invention. The same components as those of the removing apparatus 10 according to the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. The same applies to the third to ninth embodiments described below.

The stirring mechanism 72 that constitutes the removing device 70 is
One stirring blade 74 is provided on the lower end side of the rotating shaft 44. In the second embodiment, the rotary shaft 44 is rotationally driven at a higher rotation speed than that of the first embodiment under the driving action of the rotary drive source 48. Therefore, a decompression space 76 having a larger capacity than the decompression space 60 of the first embodiment is formed inside the sealed container 16 under the high-speed rotation action of the stirring blade 74, and is mixed in the oil 12. It is possible to obtain the effect that the air bubble separation / removal process can be more reliably performed in a short time.

FIG. 6 is a cross-sectional explanatory view of the essential parts of a device 80 for removing a mixed gas in oil according to a third embodiment of the present invention.

A stirring mechanism 82 constituting the removing device 80
Includes a ball screw 84 connected to the rotary drive source 48 and disposed in the sealed container 16.
A stirring blade 88 is provided on the nut member 86 that is screwed onto the screw 4.

In the third embodiment constructed as described above, the rotary drive source 48 is drive-controlled to drive the ball screw 84.
Are alternately rotated in the forward rotation direction and the reverse rotation direction for a predetermined time. Therefore, the nut member 86 screwed to the ball screw 84 moves in the vertical direction while rotating integrally with the stirring blade 88 to forcibly stir the entire oil 12 filled in the sealed container 16. The air bubbles 58 in the oil 12 can be reliably separated and removed in a short time.

FIG. 7 is an explanatory cross-sectional view of the essential parts of a device 90 for removing a mixed gas in oil according to a fourth embodiment of the present invention.

A stirring mechanism 92 that constitutes the removing device 90.
Is equipped with a rotary shaft 94 that can be connected to the rotary drive source 48, a stirring blade 96 is provided on the lower end side of the rotary shaft 94, and the first bevel gear 9 is provided substantially in the middle of the rotary shaft 94.
8 is fixed. A second bevel gear 100 meshes with the first bevel gear 98, and the second bevel gear 10
0 is fixed, and the stirring blades 104 are respectively provided on both ends of the rod 102 extending in the horizontal direction orthogonal to the rotation axis 94.
a and 104b are provided.

In the fourth embodiment thus constructed, when the rotary shaft 94 is rotated under the driving action of the rotary drive source 48, the stirring blades 96 provided on the lower side of the rotary shaft 94 are moved. The oil 12 is rotated around the vertical axis to cause stirring and flow in the oil 12. Further, the rotating shaft 94 is provided with a first bevel gear 98, and the first bevel gear 98 is provided.
Rod 10 for fixing the second bevel gear 100 that meshes with the
Agitation blades 104a, 104 provided at both ends of
b rotates around the horizontal axis to generate agitation flow in the oil 12.

As described above, in the oil 12, the stirring blade 96 rotating around the vertical axis and the stirring blades 104a and 104b rotating around the horizontal axis are arranged. Therefore, a large impact can be applied to the oil 12, and the bubbles 58 in the oil 12 can be reliably separated and removed in a short time.

FIG. 8 is a cross-sectional explanatory view of the essential parts of a device 110 for removing a mixed gas in oil according to a fifth embodiment of the present invention.

In this removing device 110, a small-diameter steel ball (small object) 11 is provided as an obstacle member in the sealed container 16.
A plurality of 2 are stored. Then, when the stirring blades 50a, 50b, and 50c are rotationally driven under the driving action of the stirring mechanism 18, the steel balls 112 in the oil 12 collide with each other to give a shock to the oil 12. As a result, the foaming of the gas mixed in the oil 12 can be positively promoted, and the removal process of the bubbles 58 mixed in the oil 12 can be reliably performed in a short time. As the obstacle member, a small three-dimensional object may be used instead of the steel ball 112.

FIG. 9 is an explanatory cross-sectional view of the main parts of a device 120 for removing a mixed gas in oil according to a sixth embodiment of the present invention.

Stirring mechanism 1 constituting this removing device 120
22 includes a rotary shaft 124 that is connected to a rotary drive source 48 and is driven to rotate.
6 is attached. The tubular body 126 has a bottomed shape, and a plurality of steel balls 112 (or a small three-dimensional object having a rectangular solid shape) are housed in the tubular body 126.

In the sixth embodiment thus constructed, when the cylindrical body 126 is rotated integrally with the rotary shaft 124 under the driving action of the rotary drive source 48, the cylindrical body 126 is housed in the cylindrical body 126. The steel balls 112 present move outward in the oil 12 under centrifugal action and collide with each other. For this reason,
The oil 12 is impacted, the gas in the oil 12 is smoothly foamed and removed, and there is an advantage that a reliable degassing process is performed in a short time.

If a plurality of mesh-like tubular bodies 126 are stacked in multiple stages and a plurality of steel balls 112 are housed in each tubular body 126 as obstacles, the oil 12
There is an effect that the degassing treatment of 1 is performed more efficiently.

FIG. 10 is a perspective view showing the principal part of a device 130 for removing a mixed gas in oil according to a seventh embodiment of the present invention.

Stirring mechanism 1 constituting this removing device 130
32 is a rotary shaft 134 that can be connected to the rotary drive source 48.
The stirring blade 136 described above is provided, and a plurality of steel balls 112 are embedded in the stirring blade 136. Therefore, under the action of the rotary drive source 48, the rotary shaft 1
When the agitating blade 136 rotates integrally with the agitator 34, the plurality of steel balls 112 embedded in the agitating blade 136 rotate and can give an impact to the oil 12.

As a result, the stirring and flow of the oil 12 by the stirring blade 136 and the impact of the plurality of steel balls 112 ensure the separation and removal of the gas mixed in the oil 12. Instead of embedding the steel ball 112 in the stirring blade 136,
The same effect can be obtained by providing an uneven portion on the surface of the stirring blade 136.

FIG. 11 is a cross-sectional plan view of essential parts of a device 140 for removing a mixed gas in oil according to an eighth embodiment of the present invention.

The hermetically sealed container 1 constituting the removing device 140
42 is set in a polygonal shape, for example, an octagonal shape, and an octagonal stirring function surface 144 is provided on the inner wall portion. Therefore, when the oil 12 stirs and flows under the action of the stirring mechanism 18, the oil 12 collides with the stirring function surface 144 and a large impact is applied. Therefore, oil 12
The separation and removal process of the gas mixed therein is smoothly performed. As the stirring function surface 144, an uneven surface or a corrugated surface may be adopted instead of the octagonal surface.

FIG. 12 is a partial perspective explanatory view of a stirring mechanism 150 which constitutes a device for removing mixed gas in oil according to a ninth embodiment of the present invention.

The stirring mechanism 150 is the stirring blade 50a described above.
Instead of the horizontal rotor blades such as ˜50c, 74 and 88, a propeller 152 is provided on the rotary shaft 44. As a result, the oil 12 is more surely and easily agitated by the rotating action of the propeller 152, so that the degassing process of the oil 12 can be efficiently performed.

[0055]

According to the method and apparatus for removing a mixed gas in oil according to the present invention, the oil is forcibly forced under the action of the stirring mechanism in a state where the pressure in the sealed container in which the oil such as the lubricating oil is sealed is reduced. Since the fluid is stirred and flowed, it is possible to give an impact to the entire oil, and the separation and removal process of the gas mixed in the oil is reliably and efficiently performed. This makes it possible to reliably remove the gas mixed in the oil in a short time with a simple process and configuration.

[Brief description of drawings]

FIG. 1 is a schematic configuration explanatory view of a removing device for carrying out a method for removing a mixed gas in oil according to a first embodiment of the present invention.

FIG. 2 is an explanatory cross-sectional view of a main part of a hermetically sealed container and a stirring mechanism that form the removing device.

FIG. 3 is a perspective view of a main part of the sealed container and the stirring mechanism.

FIG. 4 is an operation explanatory view of the sealed container and the stirring mechanism.

FIG. 5 is a cross-sectional explanatory view of a main part of a device for removing a mixed gas in oil according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional explanatory view of a main part of a device for removing a mixed gas in oil according to a third embodiment of the present invention.

FIG. 7 is an explanatory cross-sectional view of a main part of a device for removing a mixed gas in oil according to a fourth embodiment of the present invention.

FIG. 8 is an explanatory cross-sectional view of a main part of a device for removing a mixed gas in oil according to a fifth embodiment of the present invention.

FIG. 9 is a cross-sectional explanatory view of a main part of a device for removing a mixed gas in oil according to a sixth embodiment of the present invention.

FIG. 10 is a perspective view of a main part of a device for removing a mixed gas in oil according to a seventh embodiment of the present invention.

FIG. 11 is a cross-sectional plan view of relevant parts of a device for removing a mixed gas in oil according to an eighth embodiment of the present invention.

FIG. 12 is a partial perspective explanatory view of a stirring mechanism constituting a device for removing a mixed gas in oil according to a ninth embodiment of the present invention.

[Explanation of symbols]

10, 70, 80, 90, 110, 120, 130, 1
40 ... Removal device 12 ... Oil 14 ... Oil storage tank 16 ... Sealed container 18, 72, 82, 92, 122, 132, 150 ... Stirring mechanism 22, 52 ... Pipe line 24 ... Vacuum pump 26 ... Negative pressure gauge 28 ... Filter 30 ... Cylindrical body 32 ... Lower cover member 34 ... Upper cover members 44, 94, 12
4, 134 ... Rotating shaft 48 ... Rotational drive sources 50a-50c, 74, 88, 96, 104a, 104
b, 136 ... Stirring blades 54, 56 ... Coupler 84 ... Ball screw 86 ... Nut member 98, 100 ... Bevel gear 112 ... Steel ball 144 ... Stirring functional surface 152 ... Propeller

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Claims (10)

[Claims] 1. A method for removing a mixed gas in oil for separating and removing a gas mixed in oil such as lubricating oil from the oil, wherein the oil is sealed in a sealed container and the sealed A step of depressurizing the inside of the container, immersing the stirring mechanism in the oil in the sealed container, and forcibly stirring and flowing the oil under the action of the stirring mechanism to impart an impact to the oil. And a step of separating and removing a gas mixed in the oil, the method for removing the mixed gas in the oil. 2. The obstruction member according to claim 1, wherein a plurality of obstruction members are inserted into the sealed container, and the obstruction members are agitated and flow together with the oil under the action of the agitation mechanism. A method for removing a mixed gas in oil, which comprises applying an impact to the oil via 3. The method for removing a mixed gas in oil according to claim 2, wherein the obstacle member includes a small object having a spherical shape or a rectangular parallelepiped shape. 4. The method for removing a mixed gas in oil according to claim 1 or 2, wherein the sealed container has an agitation function surface, a wavy shape, or a polygonal shape on its inner wall. . 5. The removing method according to claim 1, wherein a decompression space is formed in a central portion of the sealed container under the rotating action of the stirring mechanism, and the decompression space is interposed. A method for removing a mixed gas in oil, characterized in that the gas in the oil is separated and removed. 6. A mixed gas-in-oil removing device for separating and removing gas mixed in oil such as lubricating oil from the oil, wherein the oil is sealed and communicated with a decompression source. A sealed container whose inside is depressurized, and by being immersed in the oil in the sealed container and forcibly stirring and flowing the oil, a shock is applied to the oil to remove gas mixed in the oil. A device for removing a mixed gas in oil, comprising: a stirring mechanism for separating and removing. 7. The removing device according to claim 6, further comprising: an obstacle member that is inserted into the hermetically sealed container and agitates and flows with the oil under the action of the agitating mechanism to impart an impact to the oil. A device for removing a mixed gas in oil characterized by. 8. The device for removing mixed gas in oil according to claim 7, wherein the obstacle member includes a small object having a spherical shape or a rectangular parallelepiped shape. 9. The removing apparatus according to claim 6 or 7, wherein the hermetically sealed container has an agitation function surface having an uneven shape, a wave shape or a polygonal shape on an inner wall portion. . 10. The removing device according to claim 6, wherein the stirring mechanism includes a rotary blade, a blade, a screw, or a water wheel, and the sealed container is rotated by the stirring mechanism. A depressurized space is formed in a central portion of the inside, and a gas in the oil is separated and removed through the depressurized space, thereby removing a mixed gas in oil.