JPH1133323A - Oil mist trap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contrive to maintain high oil-separating capability without clogging. SOLUTION: The oil mist trap 31 forms an air intake port 37 at a lower end and an air outlet port 43 at an upper end and is provided with a cylindrical inside case 33 passing air upward from downward, a gas-liquid separating chamber 35 demercated by the inside case 33, and impellers 71 having a plurality of blades 73 rotated by air flow inside the gas-liquid separating chamber 35 by allowing a rotating shaft center in up-and-down direction to be a center in the gas-liquid separating chamber 35. The oil mist trap 31 is provided with a cylindrical outside case 45 provided on the outside of the inside case 33, an oil passage 51 formed between the inside case 33 and the outside case 45, an oil drop-passing holes 77 allowing the gas-liquid separating chamber 35 to communicate with the oil passage 51, and a subordinate flow-introducing port 53 formed to allow the gas-liquid separating chamber 35 to communicate with the oil passage 51.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil mist trap for separating a lubricant from a mixture of a gas and a lubricant.

[0002]

2. Description of the Related Art Vacuum pumps used in various fields today use lubricating oil for the purpose of lubricating and sealing mechanical parts. When the vacuum pump is operated, this lubricating oil becomes mist and is discharged together with the air to pollute the environment. In particular, in the case of large-capacity exhaust, the oil itself may directly blow out from the discharge port. For this reason, an oil mist trap is usually attached to the discharge port of the vacuum pump in order to remove these lubricating oils.

FIG. 5 shows such an oil mist trap 11. This oil mist trap 11
Is connected to the discharge port 15 of the vacuum pump 13. The oil mist trap 11 is provided outside a mist trap inlet 17 connected to the discharge port 15, a cylindrical filter 19 made of a material such as paper connected to the mist trap inlet 17, and an outside of the filter. It has a mist trap case 21 and a discharge port 23 provided at the upper end of the mist trap case. Then, the mist-like lubricating oil discharged from the vacuum pump 13 is suction-filtered by the filter 19, and only air is discharged from the discharge port 23 to the outside air.

[0004]

However, in the oil mist trap 11, since a filter such as paper is used, if the filter adsorbs a certain amount of oil or more and becomes saturated, the adsorbing capacity is reduced. It drops sharply. At the same time, there is a problem that pressure loss increases due to clogging of the filter, and the exhaust capacity decreases.

[0005] When vacuuming is performed by a vacuum pump,
Generally, since the discharge amount is large at the beginning of drawing, the mist amount is large and the necessity of the mist trap is large. However, when the pressure is reduced to a certain degree or more, the discharge amount is reduced, so that the mist amount in the exhaust is also reduced, and the necessity of the mist trap is reduced. On the other hand, in the latter stage of the evacuation, the discharge efficiency is very important in order to bring the pressure closer to the vacuum state. However, since the filter is clogged by the mist trap at the stage prior to evacuation, the discharge efficiency cannot be increased. As described above, the conventional oil mist trap has a problem that the discharge efficiency cannot be increased because the filter is clogged when the discharge efficiency needs to be increased, although the necessity of the mist trap is low. Was.

[0006] The present invention has been made to solve such a problem, and does not cause clogging.
An oil mist trap that can efficiently perform a mist trap when the discharge amount with a large amount of oil mist is large and improves the exhaust capacity without increasing the pressure loss when the discharge amount is small and the oil mist is small. The purpose is to provide.

[0007]

According to a first feature of the present invention, an air inlet is formed at a lower end and an air outlet is formed at an upper end, and a cylindrical inner container through which air flows from below to above is provided. A first space defined, an impeller having a plurality of blades in the first space rotated by an airflow in the first space about a vertical rotation axis, and an outer side of the inner container. A cylindrical outer container disposed so as to cover the inner container at a predetermined interval from the inner container, a second space formed between the inner container and the outer container, and a tube of the inner container. An oil drop passage hole formed in a side wall having a shape communicating with the first space and the second space, and introducing the air that has risen in the first space into the upper end of the second space and descending therein. In this case, the first space and the second space are connected near the air outlet of the inner container. It is to have and a sidestream inlet formed on.

[0008] Accordingly, the air containing the oil mist entering from the air inlet rotates the fan assembly by the air flow. The rotating blade comes into contact with the oil mist in the air and adheres to the blade, and further scatters radially outward by centrifugal force. The scattered oil droplets enter the second space through the oil discharge holes. In the second space, the air introduced from the substream introduction port flows downward. For this reason, the oil droplets that have entered the second space fall down and are separated. As described above, according to the first feature, since the oil mist is separated by the rotating blades, the separation efficiency can be kept high without clogging as in the case of the paper filter. In addition, when the pump is mounted on a vacuum pump, when the discharge rate of the pump at the previous stage of evacuation is large and the amount of mixed oil mist is large, the rotation speed of the impeller also increases, and the separation capacity of oil mist must be increased. Can be. In addition, although the pump discharge amount after the evacuation is small and the amount of oil mist mixed in is small, when the high evacuation capacity is required to obtain a high vacuum, the rotation speed of the impeller decreases. Instead of reducing the capacity, the pressure loss can be reduced and the exhaust capacity can be increased.

A second feature of the present invention is that each blade of the impeller is formed with a plurality of radially outward oil grooves.

Therefore, the oil droplets attached to the blades can flow smoothly outward in the radial direction.

A third feature of the present invention is that the plurality of oil grooves are formed so as to converge radially outward.

Therefore, small oil droplets in the groove can be collected to form a large oil droplet. Therefore, the centrifugal force can be more effectively applied to the oil droplets, and the oil droplets can be more efficiently separated from the blades.

A fourth feature of the present invention is that the oil droplet passage hole has an eave portion projecting radially outward as it goes downward, and the eave portion scatters radially outward from the blade. That is, the mist is formed so as to drop below the second space.

Therefore, the mist scattered from the blades can be easily dropped below the second space, and the air is sucked from the first space by the flow of air downward in the second space. The oil droplets can be more efficiently guided to the second space.

[0015] A fifth feature of the present invention is that the auxiliary flow inlet is open downward in the first space.

Therefore, the air from which the oil mist has been separated can be easily introduced into the second space, and the oil droplets entering from the oil discharge port can be dropped and separated.

A sixth feature of the present invention is that the sub-flow inlet has an opening opening radially inward in the first space;
And a flow guide piece formed to protrude inward in the radial direction as it goes downward from the upper end edge of the opening.

Therefore, the air flowing upward in the first space can be efficiently introduced into the second space by the flow guiding pieces.

A seventh feature of the present invention is that an oil outlet having a check valve is provided at the lower end of the outer container.

Therefore, the oil can be promptly returned to the supply source as soon as a predetermined amount of the separated oil is accumulated.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a longitudinal section of an oil mist strap 31 according to the present invention. The oil mist strap 31 has a cylindrical inner case 33. The inner case 33 is for separating oil mist from air containing oil mist, and defines a gas-liquid separation chamber 35 therein. The inner case 33 is provided at its lower end with an air inlet 37 for introducing air. The air inlet 37 is normally connected to a discharge port 41 of a vacuum pump 39, and air containing oil mist is introduced from the vacuum pump 39 through the air inlet 37. An air outlet 4 for discharging air from which oil mist or the like is separated in the inner case 33 is provided at an upper end of the inner case 33.
3 are provided.

A cylindrical outer case 45 is provided outside the inner case 33. The outer case 45 is disposed with its side wall 47 separated from the side wall 49 of the inner case 33 by a predetermined distance. The inner case 33 and the outer case 45 define an oil guide 51 therebetween.
In the vicinity of the air outlet 43 of the inner case 33, a subflow inlet 53 communicating with the upper end of the oil guide 51 is formed. The substream inlet 53 is for introducing a part of the air purified in the gas-liquid separation chamber 35 to the oil guide 51. The sub-flow inlet 53 has an opening 55 and a sub-flow generating fin 57 formed to protrude inward in the radial direction from the upper end edge of the opening 55 downward. The side flow generating fins 57 are formed so that the air that has been removed from the oil mist in the gas-liquid separation chamber 35 and rises from below can be efficiently guided to the oil guide 51.

In the air inlet 37 of the inner case 33, there are provided bearings 61 supported by columns 59 in three directions. Further, bearings 65 similarly supported from three directions by columns 63 are provided in the air outlet 43. A fan assembly 67 is rotatably supported between these bearings 61 and 65. The fan assembly 67 has a rotating shaft 69 whose both ends are supported by bearings 61 and 65, and a plurality of impellers 71 fixed to the rotating shaft 69. As shown in FIG. 2, the impeller 71 has a plurality of blades 73 around a central portion thereof. This feather 7
Numeral 3 has a shape twisted in a certain direction, and is rotated by the rising exhaust gas flow. Then, the oil mist in the air is brought into contact with and attached to the rotating blade, and then scattered outward by centrifugal force. A plurality of oil guide grooves 75 are formed on the blade surface of the blade 73 from the inside to the outside in the radial direction, so that oil droplets attached to the blade can smoothly flow outward in the radial direction. . In addition, the plurality of oil guide grooves 75
Are formed so as to converge in one oil groove as going outward in the radial direction, so that a plurality of minute oil droplets are gathered into a large oil droplet and easily scattered outward.

In the side wall 49 of the inner case 33, a large number of oil drop passage holes 77 communicating with the oil guide 51 from the gas-liquid separation chamber 35,
... are formed. These oil droplet passage holes 77 are formed at equal positions in the circumferential direction at positions outside the plurality of impellers 71,. The oil droplets scattered from the blades 73 can pass through the oil droplet passage holes 77 from the gas-liquid separation chamber 35 to the oil guide 51. As shown in FIG. 3, an eave portion 79 protruding outward in the radial direction is provided on the upper edge of the oil droplet passage hole 77 as shown in FIG. This eave part 79
Is for catching the oil droplets scattered radially outward from the blades on the inner wall thereof and dropping them to the oil guide 51 below to guide them.

On the other hand, an oil reservoir 81 is provided at the lower end of the outer case 45 for temporarily storing the oil that has fallen. An oil discharge port 85 having a check valve 83 is provided at the lower end of the oil reservoir 81. This oil outlet 85
Is for returning the lubricating oil stored in the oil reservoir 81 to a vacuum pump or the like as necessary.

The operation and operation of the oil mist trap having such a configuration will be described.

First, when the vacuum pump 39 is started, the discharge air in which mist-like lubricating oil is mixed with air is discharged from the discharge port 41.
Is discharged from This discharge air is The air enters the inner case 33 of the oil mist trap 31 from the air inlet 37 connected to the discharge port 41 and rises inside the gas-liquid separation chamber 35.

The air rising in the gas-liquid separation chamber 35 is
The fan assembly 67 is rotated while hitting the plurality of blades 73. Then, mist-like oil droplets in the air come into contact with and adhere to the rotating blades 73.

The oil droplets adhering to the rotating blade 73 are:
The oil is moved radially outward along the oil guide groove 75 by the centrifugal force. Here, since the plurality of oil guide grooves 75 are formed so as to converge toward the outside, the oil droplets which were initially small gradually become larger, and are likely to be scattered outward by centrifugal force. . The oil droplet that has become larger in this way is blown outward from the outer end of the blade 73 and is introduced into the oil guide 51 through the oil droplet passage hole 77.

Thus, the rotating fan assembly 6
The air from which the lubricating oil mist is separated after passing through the air outlet 7 is discharged from the air outlet 43 at the upper end of the gas-liquid separation chamber 35 into the outside air. Guided inside. At this time, since the sub-flow generating fins 57 are formed in the sub-flow introduction port 53 so as to protrude inward downward, the rising air is efficiently guided into the oil guide 51.

The air guided into the oil guide 51 flows downward therethrough, and the oil droplets entering the oil guide 51 from the oil drop passage hole 77 flow downward and fall. FIG.
As shown in the figure, the air flowing downward in the oil guide 51 sucks the air in the gas-liquid separation chamber 35 into the oil guide 51, so that the oil droplets blown from the blades can be more efficiently collected in the oil guide 51. You can lead inside. As described above, since the oil guide 51 is provided separately from the gas-liquid separation chamber 35, the oil droplets can be dropped and separated without being hindered by the rising air flow in the gas-liquid separation chamber 35. it can.

The oil droplets falling inside the oil guide 51 are stored in an oil sump 81 and returned to the vacuum pump 39 when a predetermined amount of lubricating oil has accumulated.

In this manner, the oil mist exhausted from the vacuum pump is attached to the rotating blades and separated by centrifugal force, so that air and lubricating oil can be efficiently separated.

In general, when a vacuum pump is used to evacuate, the discharge amount is largest immediately after the start of the evacuation, and thereafter, the discharge amount gradually decreases as the inside of the container approaches vacuum. For this reason, immediately after the start of evacuation with a large discharge amount, the amount of mixed oil mist is the largest, and the ability to separate a large amount of oil mist is required here.

In response to such a demand, in the oil mist trap 31, as the discharge amount from the vacuum pump increases, the rotation speed of the fan assembly 67 increases in proportion thereto. Therefore, the possibility that the oil mist hits the blade 73 increases, and the ability to separate the oil mist increases. Therefore, when the oil mist increases most, the separation ability also increases, so that the air and the oil mist can be efficiently separated.

In addition, since the rotating blades are used, as in the case of using a paper filter, clogging is caused by the absorbed oil, and as a result, not only the separation ability is reduced but also the pressure loss is increased. Nor. Therefore, a high separation ability can be maintained without impairing the ejection ability.

On the other hand, in the latter stage of the evacuation, the discharge amount decreases, so that the mixing amount of the oil mist also decreases.
Therefore, at this stage, the ability to separate the oil mist is not so required. However, in order to obtain a high vacuum, a high air discharge capacity is required even at this stage.

In the oil mist trap 31 of this embodiment, when the discharge amount is reduced, the rotation speed of the fan is reduced. For this reason, as the mixing amount of the oil mist decreases, the separating ability of the oil mist also decreases, and the pressure loss also decreases due to the decrease in the rotation speed of the fan. For this reason, in the latter stage of evacuation where the oil mist separation ability is not so required, instead of lowering the separation ability, it is possible to exert a high air exhausting ability, and thus it is possible to efficiently obtain a high degree of vacuum.

As described above, the oil mist trap 3
In the case of 1, the oil mist is attached by the rotating blades 73, and the oil mist is made to fly outward by centrifugal force and is separated into the oil guide 51 through the oil droplet passage hole 77. As in the case, the oil separation efficiency does not decrease or the pressure loss does not increase due to clogging, and both high oil separation efficiency and low pressure loss can be achieved.

In addition, when the pump is mounted on a vacuum pump, the rotation speed of the fan assembly also increases when the discharge amount of the pump at the stage prior to evacuation is large and the amount of oil mist mixed is large, and the oil mist is separated. You can improve your ability. In addition, although the pump discharge amount after the evacuation is small and the amount of oil mist mixed in is small, when the high evacuation capacity is required to obtain a high vacuum, the rotational speed of the fan assembly is reduced. Instead of reducing the separation capacity, the pressure loss can be reduced and the exhaust capacity can be increased.

In the above embodiment, the oil guide groove is formed so that a plurality of oil guide grooves gradually converge as shown in FIG. 1. However, the present invention is not limited to this. As shown, the oil groove may be formed linearly up to the outer end of the blade, and a plurality of oil grooves may gather at the outer end.

[0043]

According to the present invention, the oil mist is attached by the rotating blades and separated by centrifugal force, so that the oil separation efficiency can be improved without clogging as in the case of the paper filter. Can be kept high. In addition, when the pump is mounted on a vacuum pump, when the discharge rate of the pump at the previous stage of evacuation is large and the amount of mixed oil mist is large, the rotation speed of the impeller also increases, and the separation capacity of oil mist must be increased. Can be. In addition, although the pump discharge amount after the evacuation is small and the amount of oil mist mixed in is small, when the high evacuation capacity is required to obtain a high vacuum, the rotation speed of the impeller decreases. Instead of reducing the capacity, the pressure loss can be reduced and the exhaust capacity can be increased.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an oil mist trap according to one embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is an enlarged view of a portion III in FIG.

FIG. 4 is an enlarged view of a tip of a blade.

FIG. 5 is a schematic view showing the structure of a conventional oil mist trap.

[Explanation of symbols]

 33 Inner Case 35 Gas-Liquid Separation Chamber 37 Air Inlet 43 Air Outlet 45 Outer Case 49 Side Wall 51 Oil Guide 53 Subflow Inlet 55 Opening 57 Subflow Generation Fin 71 Impeller 73 Blade 75 Oil Guide Groove 77 Oil Drop Hole 79 Eave section 83 Check valve 85 Oil outlet

Claims (7)

[Claims] An air inlet is formed at a lower end and an air outlet is formed at an upper end, and a cylindrical inner container through which air flows upward from below, a first space defined by the inner container, In the first space, an impeller having a plurality of blades rotated by an air flow in the first space around a vertical rotation axis, and a certain distance from the inner container outside the inner container. A cylindrical outer container disposed so as to cover the inner container with a space therebetween; a second space formed between the inner container and the outer container; formed on a cylindrical side wall of the inner container. An oil droplet passage hole communicating the first space and the second space, and introducing the air that has risen in the first space into an upper end of the second space and lowering the inside thereof. Therefore, the first space is provided near the air outlet of the inner container. Serial second space and an oil mist trap anda sidestream inlet port formed so as to communicate. 2. The oil mist trap according to claim 1, wherein a plurality of oil grooves extending radially outward are formed in each blade of the impeller. 3. The oil mist trap according to claim 2, wherein said plurality of oil grooves are formed so as to converge radially outward. 4. The oil droplet passage hole has an eave portion projecting outward in the radial direction as it goes downward, and the eave portion serves to remove mist scattered outward from the blade in the radial direction. 2. The oil mist trap according to claim 1, wherein the oil mist trap is formed so as to drop below the space. 5. The oil mist trap according to claim 1, wherein the substream introduction port opens downward in the first space. 6. The sub-flow introduction port has an opening that opens radially inward into the first space, and a direction that moves radially inward downward from an upper end edge of the opening. 2. The oil mist trap according to claim 1, further comprising a flow guide piece protruding from the oil mist trap. 7. An oil discharge port having a check valve is provided at a lower end of the outer container.
The described oil mist trap.