JP7645324B2 - Oil separator and compressed air drying system - Google Patents

Description

The present invention relates to an oil separator and compressed air drying system that separates oil contained in the air that has passed through the equipment from the air.

Trucks, buses, construction machinery and other vehicles use compressed air sent from a compressor directly connected to the engine to control systems such as the brakes and suspension. This compressed air contains moisture from the atmosphere and oil that lubricates the inside of the compressor. If compressed air containing this moisture and oil gets into each system, it can cause rust and swelling of rubber components (O-rings, etc.), resulting in malfunctions. For this reason, an air dryer is installed downstream of the compressor to remove moisture and oil from the compressed air.

The air dryer is equipped with a desiccant that removes moisture and a filter that captures oil. This air dryer has a dehumidifying effect that removes moisture from the compressed air sent from the compressor, and a regenerating effect that expels moisture adsorbed by the desiccant to the outside.

Because the air discharged from the air dryer when the desiccant is regenerated contains oil as well as moisture, an oil separator may be installed at the drain outlet of the air dryer in consideration of the environmental impact (see Patent Document 1). This oil separator has a collision material inside the housing against which the air containing moisture and oil collides, and separates the moisture and oil contained in the air by colliding the air against the collision material. The separated oil is collected inside the oil separator, and the clean air from which the oil has been removed is released to the outside.

JP 2014-091059 A

By the way, compressed air that has been dried by the air dryer is used to regenerate the desiccant in the air dryer. This causes a problem in that the exhaust noise becomes loud when the clean air is exhausted from the oil separator.

The present invention was made in consideration of these circumstances, and its purpose is to reduce the noise generated when clean air is exhausted.

The means for solving the above problems and their effects will be described below.
The oil separator that solves the above problem comprises a housing having an intake port through which compressed air flows in and an exhaust port through which clean air is discharged, and a filter section provided within the housing that separates the compressed air into gas and liquid, the filter section having a filter inlet through which compressed air flows into the filter section and a filter outlet through which clean air that has passed through the filter section flows out, and the opening area of the exhaust port is larger than the opening area of the filter outlet.

With the above configuration, the opening area of the exhaust port is larger than the opening area of the filter outlet, so the flow rate of the clean air decreases as it moves from the filter outlet to the exhaust port. This reduces the exhaust noise that occurs when the clean air passes through the filter outlet and is exhausted from the exhaust port.

In the above oil separator, a porous plate having a plurality of through holes is provided in the passage including the filter outlet and the exhaust port, and it is preferable that the opening area of the porous plate is larger than the opening area of the filter outlet.

According to the above configuration, the clean air that has passed through the filter section is straightened by the multiple through holes provided in the perforated plate and discharged to the exhaust port side. This makes it possible to suppress noise caused by the generation of turbulence. In addition, since the opening area of the perforated plate is larger than the opening area of the filter outlet, the flow speed of the clean air decreases as it moves from the filter outlet toward the perforated plate. This makes it possible to reduce the discharge noise of the clean air.

In the above oil separator, it is preferable that a plurality of vent holes are provided at the filter outlet, and the porous plate has a plurality of through holes having an inner diameter larger than that of the vent holes.
According to the above-mentioned configuration, the flow velocity of the clean air can be reduced between the porous plate and the filter outlet. In this way, the flow velocity of the clean air is reduced before it is discharged from the filter outlet, so that the discharge noise when the clean air is discharged from the exhaust port can be reduced.

In the above oil separator, a first porous plate having a plurality of through holes and a second porous plate arranged closer to the exhaust port than the first porous plate are provided in the passage including the filter outlet and the exhaust port, a silencer is provided between the first porous plate and the second porous plate, and it is preferable that the opening area of the first porous plate is larger than the opening area of the second porous plate.

According to the above configuration, the opening area of the first porous plate is larger than the opening area of the second porous plate, so clean air can be circulated in the silencer placed between them. This enhances the noise reduction effect of the silencer.

In the above oil separator, it is preferable that an inner diameter of the second through hole formed in the second porous plate is smaller than an inner diameter of the first through hole formed in the first porous plate.
According to the above configuration, the clean air can be dispersed and discharged from the second through hole, compared to when the second through hole has an inner diameter larger than that of the first through hole. By dispersing the clean air in this manner, the flow velocity of the clean air that has passed through the filter outlet can be reduced, and therefore the discharge sound when the clean air is discharged from the exhaust port can be reduced.

It is preferable that the oil separator has a plurality of air holes at the filter outlet, a first expansion chamber between the intake port and the filter section, and a second expansion chamber between the filter outlet and the exhaust port.

According to the above configuration, the compressed air flowing in from the intake port first expands by flowing into the first expansion chamber, and then flows into the filter from the filter inlet. The clean air is compressed as it passes through the filter and is discharged from the filter outlet. The compressed clean air expands again by flowing into the second expansion chamber. In this way, the compressed air flowing in from the intake port expands, is compressed, and then expands again, suppressing the pulsation of the compressed air and clean air, and suppressing noise associated with the pulsation.

The present invention can reduce the noise generated when exhausting clean air.

FIG. 1 is a block diagram showing a schematic configuration of a compressed air drying system to which an oil separator is applied according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the oil separator of the embodiment. FIG. 2 is an enlarged view of the vicinity of a filter outlet of the oil separator according to the embodiment. FIG. 2 is an enlarged view of the vicinity of an exhaust port of the oil separator according to the embodiment. FIG. 4 is a cross-sectional view of an oil separator according to a modified example. FIG. 4 is a cross-sectional view of an oil separator according to a modified example.

Hereinafter, an embodiment in which an oil separator is applied to a compressed air drying system mounted on a vehicle will be described with reference to FIGS.
As shown in FIG. 1, a compressed air drying system that removes oil and moisture from compressed air sent from the compressor 1 is provided downstream of the compressor 1. The compressed air drying system includes an air dryer 2 that removes oil and moisture from compressed air. A desiccant 2a is provided inside the air dryer 2. The air dryer 2 performs a load operation in which compressed air is passed through the desiccant 2a to remove moisture and oil, and an unload operation in which the desiccant 2a is regenerated by discharging moisture and oil captured by the desiccant 2a to the outside. The air dryer 2 sends out dried compressed air, which is compressed air from which oil and moisture have been removed by the load operation, to a system tank 6. The system tank 6 supplies compressed air to each system such as a brake and a suspension. When the pressure in the system tank 6 reaches a predetermined value, an exhaust valve 2b of the air dryer 2 is opened to perform an unload operation. When the exhaust valve 2b is opened, dry compressed air is supplied from the system tank 6 to the air dryer 2, and the dry compressed air that has flowed into the air dryer 2 flows in the opposite direction to that during load operation. This removes moisture and oil trapped in the desiccant 2a. The removed moisture and oil are discharged together with air from the drain outlet 2c of the air dryer 2. The air discharged from the air dryer 2 at this time is called purge air.

In addition, in the compressed air drying system, an oil separator 5 is connected to the drain outlet 2c of the air dryer 2. The oil separator 5 is connected to the drain outlet 2c of the air dryer 2 via a connection hose 2d.

The oil separator 5 separates the purge air containing oil and moisture into clean air and drain liquid, which is a liquid containing oil and moisture. The oil separator 5 discharges the separated clean air from the exhaust port 5c. The oil separator 5 also stores the separated drain liquid in its housing 5a.

Next, the oil separator 5 will be described in detail with reference to FIG. 2. The housing 5a of the oil separator 5 includes a body 10 and a drain bowl 30. The body 10 includes an intake port 16 and an exhaust port 17 having an exhaust port 5c. The exhaust port 5c is circular and has a diameter (inner diameter) D10.

The body 10 is formed in a cylindrical shape. One end of the body 10 is closed. An opening 11 is provided at the other end of the body 10. A female screw 12 is provided on the inner peripheral surface of the body 10, on the opening 11 side.

The drain bowl 30 is formed in a cylindrical shape. One end of the drain bowl 30 has a bottom. The other end of the drain bowl 30 has an opening 31. Inside the drain bowl 30, a storage section 32 is provided, which is a space for storing drain liquid. A male screw 33 is provided on the outer circumferential surface of the opening 31 of the drain bowl 30. The female screw 12 of the body 10 and the male screw 33 of the drain bowl 30 are screwed together, thereby fixing the drain bowl 30 to the body 10. The oil separator 5 is fixed to the vehicle side with the body 10 positioned vertically upward and the drain bowl 30 positioned vertically downward, and stores drain liquid in the drain bowl 30. The stored drain liquid is discharged from a drain outlet (not shown) provided in the drain bowl 30. The stored drain liquid can also be discarded by removing the drain bowl 30 from the body 10.

A filter unit 40 is fixed to the bottom of the body 10. The filter unit 40 includes a filter case 41 as a filter housing, a filter 42 housed inside the filter case 41, and a filter lid 43.

An annular protrusion 13 is provided on the inside of the body 10, in the center of the bottom in the radial direction. A female screw 14 is provided on the inner peripheral surface of the annular protrusion 13. The filter case 41 is formed in a cylindrical shape. A ceiling portion 53 is provided on one end of the filter case 41. An opening portion 54 is provided on the other end of the filter case 41. An annular protrusion 51 that protrudes outward from the filter case 41 is provided on the center of the ceiling portion 53 in the radial direction. A male screw 52 is provided on the outer peripheral surface of the annular protrusion 51. The filter section 40 is fixed to the body 10 by screwing the female screw 14 of the body 10 into the male screw 52 of the filter case 41.

A plurality of first air vents 56 are formed in the peripheral wall 55 of the filter case 41. A plurality of rows of the first air vents 56 are formed in the peripheral wall 55 along the circumferential direction. A filter outlet 57 is provided in the center of the ceiling 53, in a portion surrounded by the annular protrusion 51. The filter outlet 57 has a plurality of air vents 58 that communicate between the inside and outside of the filter case 41.

The filter lid 43 is provided to cover the opening of the filter case 41. A plurality of exhaust holes 44 are formed in the filter lid 43. The filter 42 is housed in the space formed by the filter case 41 and the filter lid 43. The filter 42 has a large number of pores through which compressed air passes. The filter 42 is made of, for example, a sponge (urethane foam) having a large number of bubbles, a molded metal material such as metal wire or metal foil having a large number of pores (crushed aluminum), glass fiber, etc.

The compressed air that flows into the filter 42 from the first air vent 56 of the filter case 41 collides with the filter 42, causing gas-liquid separation. The drain liquid separated by the filter 42 flows vertically downward through the filter 42 due to gravity, and falls into the storage section 32 through the discharge hole 44. The clean air separated by the filter 42 is discharged from the filter section 40 through the air vent 58 of the filter outlet 57.

The intake port 16 of the body 10 is connected to the air dryer 2 via a connection hose 2d (see FIG. 1). The intake port 16 is connected to a first passage 18 that extends toward the opening 11 of the body 10.

The first passage 18 is connected to the storage section 32 of the drain bowl 30. The diameter of the first passage 18 increases stepwise or continuously as it approaches the storage section 32. The first passage 18 and the storage section 32 of the drain bowl 30 function as a first expansion chamber 34 in which the compressed air flowing in through the intake port 16 expands. The expansion of the compressed air in the first expansion chamber 34 makes it easier for oil and moisture in the compressed air to condense.

The exhaust port 17 of the body 10 discharges the clean air separated by the filter unit 40 to the outside. The exhaust port 17 is connected to the second passage 19. The second passage 19 is formed in a roughly L-shape and consists of a small passage 21 connected to the filter outlet 57 and a small passage 22 provided between the small passage 21 and the exhaust port 17. The small passage 21 extends along the axial direction of the drain bowl 30. The small passage 22 extends in a direction perpendicular to the direction in which the small passage 21 extends. The second passage 19 functions as a second expansion chamber 23 in which the compressed air expands. Note that the space in front of the filter case 41 is the first expansion chamber 34 and the space behind it is the second expansion chamber 23, but the space inside the filter case 41 also has the function of expanding the compressed air by passing through the first air hole 56, although the expansion effect is lower than that of the first expansion chamber 34 and the second expansion chamber 23.

The small passage 22 on the exhaust port 17 side of the second passage 19 is provided with a first porous plate 61, a second porous plate 62, and a silencer 65 arranged between the first porous plate 61 and the second porous plate 62. The first porous plate 61 has a plurality of first through holes 63 penetrating in the thickness direction. The second porous plate 62 has a plurality of second through holes 64 penetrating in the thickness direction. The silencer 65 has a plurality of pores through which compressed air passes, and is made of, for example, a sponge (urethane foam) having a large number of bubbles, a metal material such as a metal wire or metal foil, and a material having a large number of pores (crushed aluminum), etc. The silencer 65 may be made of the same material as the filter 42, or a different material.

The first porous plate 61 is disposed on the filter outlet 57 side, and is fixed by being sandwiched between a step 25 formed on the inner surface of the second passage 19 and a silencer 65. The second porous plate 62 is disposed on the exhaust port 17 side. The second porous plate 62 is prevented from coming off the body 10 by a retainer ring 66 being fitted into a groove 28 formed on the inner surface of the second passage 19.

Next, the configuration of the second passage 19 will be described in detail with reference to FIGS.
3, the ventilation holes 58 provided at the filter outlet 57 are formed in a circular shape having a diameter D1. The ventilation holes 58 may be formed at equal intervals in the ceiling portion 53, or may be formed randomly. When the number of the ventilation holes 58 is L, the opening area S1 at the filter outlet 57 is "π{(D1)/2} ² ·L".

Since exhaust port 17 has a circular shape with a diameter D10, its opening area S10 is "π{(D10)/2} ² ". The opening area S10 of exhaust port 17 is larger than the opening area S1 of filter outlet 57 (opening area S10>opening area S1).

As shown in Fig. 4, the first through holes 63 provided in the first porous plate 61 are circular with a diameter D2, which is larger than the diameter D1 of the vent hole 58 of the filter outlet 57 (diameter D2>diameter D1). When the number of the first through holes 63 is M, the opening area S2 of the first porous plate 61 is "π{(D2)/2} ² ·M", which is larger than the opening area S1 of the filter outlet 57 (opening area S2>opening area S1). The opening area S10 of the exhaust port 17 is larger than the opening area S2 of the first porous plate 61 (opening area S10>opening area S2>opening area S1). The number of the first through holes 63 (M) is smaller than the number of the filter outlets 57 (L) (number M<number L).

The second through holes 64 provided in the second porous plate 62 are circular and have a diameter D3, which is smaller than the diameter D1 of the ventilation holes 58 of the filter outlet 57 (diameter D3<diameter D1<diameter D2). The depth L3 of the second through holes 64 is larger than the diameter D3. The second through holes 64 may be formed at equal intervals or may be formed randomly. When the number of the second through holes 64 is N, the opening area S3 of the second porous plate 62 is "π{(D3)/2} ² ·N". The number (N) of the second through holes 64 is larger than the number (L) of the ventilation holes 58 of the filter outlet 57 (number N>number L>number M). The opening area S3 of the second porous plate 62 is larger than the opening area S1 at the filter outlet 57 and smaller than the opening area S2 of the first porous plate 61 (opening area S2>opening area S3>opening area S1).

Next, referring to FIG. 2, the operation of the oil separator 5 will be explained. When the exhaust valve 2b of the air dryer 2 is opened and unloading operation is performed, drain liquid containing oil and water is discharged into the oil separator 5 together with the purge air. The drain liquid contained in the purge air is in the form of a mist or liquid. The purge air containing the drain liquid flows into the oil separator 5 from the intake port 16.

The purge air expands by flowing into the first expansion chamber 34 from the intake port 16. The pressure of the expanded purge air in the first expansion chamber 34 is maintained at a value greater than atmospheric pressure. The expanded purge air flows into the filter section 40 through the first air vent 56 of the filter case 41. The purge air that flows into the filter section 40 passes through the filter 42 while repeatedly colliding with the wall surface of the pores and colliding (friction) with other compressed air within the pores. As a result, the purge air is separated into drain liquid and clean air from which the drain liquid has been removed. The separated drain liquid falls into the storage section 32. The separated clean air heads toward the filter outlet 57. At this time, the clean air expands once as it flows into the filter case 41, but is compressed as it heads toward the filter outlet 57, which has a small opening area.

The clean air is straightened by passing through the multiple air vents 58 in the filter outlet 57. This makes it possible to suppress the generation of turbulence in the second passage 19, thereby reducing noise caused by the generation of turbulence. In addition, the clean air is compressed by passing through the air vents 58 in the filter outlet 57, and then expands in the second expansion chamber 23 (second passage 19).

The flow of clean air bends along the direction of the second passage 19 and heads toward the first porous plate 61. In addition, when clean air flows along the second passage 19, the opening area S2 of the first porous plate 61 is larger than the opening area S1 of the filter outlet 57, and the first through hole 63 provided in the first porous plate 61 has a larger diameter than the air vent 58 formed in the filter outlet 57, so the flow speed of the clean air decreases as it moves from the filter outlet 57 toward the first porous plate 61. By decreasing the flow speed of the clean air in this way, it is possible to reduce the exhaust sound generated while the clean air passes through the filter outlet 57 and is exhausted from the exhaust port 17.

The flow of clean air, whose flow velocity has been reduced, is compressed just before the first porous plate 61, and the flow velocity temporarily changes from just before passing through the first through-hole 63 to just after passing through. If the silencer 65 is a porous material made of metal such as crushed aluminum, the clean air repeatedly collides with the inner wall surface of the pores, or the clean air flow repeatedly collides within the pores. This reduces the vibration of the clean air, and suppresses the generation of noise. If the silencer 65 is a porous material made of synthetic resin with air bubbles, such as a sponge, sound is absorbed by the clean air repeatedly colliding with the inner wall surface of the air bubbles, or the clean air flow repeatedly collides within the air bubbles.

The opening area S3 of the second porous plate 62, which is provided on the exhaust port 17 side of the silencer 65, is smaller than the opening area S2 of the first porous plate 61. Therefore, compared to when the second porous plate 62 has an opening area larger than that of the first porous plate 61, the clean air is less likely to be discharged from the second through holes 64 of the second porous plate 62, and the clean air circulates within the silencer 65. In this way, even if the flow rate of the clean air is reduced in front of the first porous plate 61, by circulating the clean air within the silencer 65, the chances of collision between the silencer 65 and the clean air and collision between the clean air within the pores increase, and the effect of reducing noise (silencing effect) can be improved.

The diameter of the second through holes 64 of the second porous plate 62 is smaller than the diameter of the first through holes 63 of the first porous plate 61. Therefore, compared to when the diameter of the second through holes 64 is larger than the diameter of the first through holes 63, the clean air can be dispersed and discharged from the second through holes 64. Dispersing and discharging the clean air in this manner can reduce noise associated with the discharge of the clean air.

The clean air is diffused by repeated collisions within the silencer 65. The second porous plate 62 has more second through holes 64 than the first through holes 63 of the first porous plate 61, so that the diffused clean air is discharged from each second through hole 64, preventing the pressure in the silencer 65 from becoming excessively high. The clean air that passes through the second through holes 64 of the second porous plate 62 is discharged to the outside from the exhaust port 17.

The opening area S10 of the exhaust port 5c of the exhaust port 17 is larger than the opening area S1 of the filter outlet 57. In addition, in the second passage 19 leading from the filter outlet 57 to the exhaust port 17, the opening area S2 of the first porous plate 61 and the opening area S3 of the second porous plate 62 are larger than the opening area S1 of the filter outlet 57. Therefore, although the flow speed may increase locally, such as when passing through the first porous plate 61, overall, the flow speed of the clean air decreases as it approaches the exhaust port 17. Since the exhaust sound increases exponentially as the air flow speed increases, the flow speed in the second passage 19 is reduced to reduce the exhaust sound of the clean air.

The purge air flowing in from the intake port 16 expands in the first expansion chamber 34 and is compressed when it flows into the filter section 40 through the first air hole 56. The clean air separated by the filter 42 expands again by flowing from the filter section 40 into the second expansion chamber 23 consisting of the second passage 19, and is compressed again by passing through the first porous plate 61. In this way, the cycle of expansion and compression is repeated multiple times, thereby suppressing the pulsation of the compressed air (or clean air). This also suppresses the noise associated with the pulsation.

Furthermore, even if air expands in the second expansion chamber 23, the flow of clean air is straightened by the first through-hole 63 of the first porous plate 61 and the second through-hole 64 of the second porous plate 62. Therefore, the generation of turbulence is suppressed downstream of the second passage 19 and before the exhaust port 17, and the noise associated with turbulence is reduced.

As described above, according to this embodiment, the following effects can be obtained.
(1) Because the opening area of the exhaust port 17 is larger than the opening area of the filter outlet 57, the flow velocity of the clean air decreases as it moves from the filter outlet 57 to the exhaust port 17. This makes it possible to reduce the exhaust noise generated while the clean air passes through the filter outlet 57 and is exhausted from the exhaust port 17.

(2) The second passage 19 is provided with a first porous plate 61 and a second porous plate 62. Therefore, the clean air that has passed through the filter 42 is straightened by the first through hole 63 provided in the first porous plate 61 and the second through hole 64 provided in the second porous plate 62, and is discharged to the exhaust port 17 side. This suppresses the generation of turbulence near the exhaust port 17, thereby suppressing noise associated with the turbulence. In addition, the opening area of the first porous plate 61 and the opening area of the second porous plate 62 are larger than the opening area of the filter outlet 57. Therefore, the flow speed of the clean air decreases as it moves from the filter outlet 57 to the first porous plate 61 side. This makes it possible to reduce the discharge sound of the clean air.

(3) The filter outlet 57 is provided with a plurality of ventilation holes 58, and the first porous plate 61 has a plurality of first through holes 63 with a diameter (inner diameter) larger than that of the ventilation holes 58. This allows the flow rate of the clean air to be reduced between the first porous plate 61 and the filter outlet 57. In this way, the flow rate of the clean air is reduced before it is discharged from the filter outlet, so the discharge sound when the clean air is discharged from the exhaust port 17 can be reduced.

(4) The opening area of the first porous plate 61 is larger than the opening area of the second porous plate 62. In addition, a silencer 65 is provided between the first porous plate 61 and the second porous plate 62. Therefore, clean air can be circulated in the silencer 65 arranged between the first porous plate 61 and the second porous plate 62. Therefore, the noise reduction effect of the silencer 65 can be enhanced.

(5) The diameter (inner diameter) of the second through holes 64 formed in the second porous plate 62 is smaller than the diameter (inner diameter) of the first through holes 63 formed in the first porous plate 61. Therefore, while having a smaller opening area than the first porous plate 61, the number of second through holes 64 can be increased to disperse and discharge clean air. This enhances the effect of suppressing the generation of turbulence, and suppresses noise associated with the generation of turbulence.

(6) A first expansion chamber 34 is provided between the intake port 16 and the filter 42, and a second expansion chamber 23 is provided between the filter outlet 57 and the exhaust port 17. For this reason, the compressed air flowing in from the intake port 16 first expands by flowing into the first expansion chamber 34, and then flows into the filter 42 from the first air hole 56, which is the filter inlet. In addition, the clean air is compressed when it passes through the filter 42 and is discharged from the filter outlet 57. The compressed clean air expands again by flowing into the second expansion chamber 23. In this way, the compressed air flowing in from the intake port 16 is compressed after expansion and then expands again, so that the pulsation of the compressed air and the clean air can be suppressed, and the noise associated with the pulsation can be suppressed.

Other Embodiments
The above embodiment can also be implemented in the following forms.
The exhaust port 5c of the exhaust port 17 may have a shape other than a circle as long as the opening area thereof is larger than the filter outlet 57.

- The first through holes 63 of the first porous plate 61 and the second through holes 64 of the second porous plate 62 do not have to be circular. In this case, the opening area of the first porous plate 61 is calculated by multiplying the opening area of the first through holes 63 by the number (M). The opening area of the second porous plate 62 is calculated by multiplying the opening area of the second through holes 64 by the number (N).

- In the above embodiment, the number of first through holes 63 formed in the first porous plate 61 is less than the number of second through holes 64 formed in the second porous plate 62. In addition to this embodiment, if a sufficient noise reduction effect is obtained by passing clean air through the silencer 65, the number of first through holes 63 may be the same as or greater than the number of second through holes 64 formed in the second porous plate 62.

- In the above embodiment, the opening area of the first porous plate 61 is larger than the opening area of the second porous plate 62. In addition to this aspect, if noise can be sufficiently reduced even without the effect of circulating clean air within the silencer 65, the opening area of the first porous plate 61 may be the same as or smaller than the opening area of the second porous plate 62.

- In the above embodiment, a silencer 65 is provided between the first porous plate 61 and the second porous plate 62, but this may be omitted. If at least the first porous plate 61 and the second porous plate 62 are present, the straightening effect of the clean air can be improved.

In the above embodiment, the diameter D1 of the vent hole 58 of the filter outlet 57 is made larger than the diameter D3 of the second through hole 64 of the second porous plate 62, and the diameter D2 of the first through hole 63 of the first porous plate 61 is made larger than the diameter D1 of the vent hole 58 (diameter D3 < diameter D1 < diameter D2). However, the diameter D1 of the vent hole 58, the diameter D2 of the first through hole 63, and the diameter D3 of the second through hole 64 are not limited to the above-mentioned relationship. For example, the diameter D3 of the second through hole 64 may be larger than the diameter D1 of the vent hole 58 and smaller than the diameter D2 of the first through hole 63 (diameter D1 < diameter D3 < diameter D2). In addition, the diameter D3 of the second through hole 64 may be the same as or larger than the diameter D2 of the first through hole 63 (diameter D1 < diameter D2 = diameter D3, or diameter D1 < diameter D2 < diameter D3). The relationship between diameters D1 to D3 can be changed depending on the configuration of the oil separator 5, etc.

- In the above embodiment, the first porous plate 61 and the second porous plate 62 are provided in the second passage 19, but a single porous plate may be provided, or the porous plate may be omitted. Even in these cases, the exhaust noise of the clean air can be reduced as long as the opening area of the exhaust port 17 is at least larger than the opening area of the filter outlet 57.

- As shown in FIG. 5, the filter outlet of the oil separator 5 may be provided in the peripheral wall of the filter case. This oil separator 5 includes a body 110 and a drain bowl 130 as a housing. The drain bowl 130 is provided with a drain outlet 159 for discharging drain liquid. The body 110 has an intake port 116 and an exhaust port 117, and a first expansion chamber 134 for expanding the compressed air flowing in from the intake port 116. The filter section 140 is fixed to the body 110 via a cover 111. The filter section 140 includes a filter case 141, a filter 142, and a filter lid 143. A plurality of air holes 156, which are filter inlets, are formed in the ceiling of the filter case 141, and an air hole 158, which is a filter outlet, is formed through the peripheral wall of the filter case 141. In other words, the filter outlet does not necessarily have to be formed in the ceiling of the filter case. A plurality of ventilation holes 158 are formed along the circumferential direction of the filter case 141. Although FIG. 5 shows an embodiment in which a perforated plate is not provided on the exhaust port 117 side, a perforated plate may be provided on the oil separator 5 of FIG. 5. Regardless of the presence or absence of a perforated plate, the opening area of the exhaust port 117 is larger than the opening area of the filter outlet consisting of the plurality of ventilation holes 158. The compressed air flowing in from the intake port 116 expands in the first expansion chamber 134 and then flows into the filter section 140 from the ventilation holes 156 of the filter case 141. The drain liquid separated by the filter 142 flows down from the discharge hole 144 of the filter cover 143 into the storage section 132. The separated clean air passes through each ventilation hole 158 formed in the peripheral wall of the filter case 141 and passes through the space between the drain bowl 130 and the filter section 140 toward the exhaust port 117. In this way, the opening area of the exhaust port 117 is larger than the opening area of the filter outlet, so that the flow rate is reduced at least when the clean air flows from the filter outlet toward the exhaust port 117. This reduces the noise that accompanies the exhaust of the clean air.

- In the above embodiment and other embodiments, the first expansion chamber 34, 134 and the second expansion chamber 23 are provided in the oil separator 5, but if pulsation of the compressed air sent from the air dryer 2 is not expected, these expansion chambers may be omitted.

As shown in FIG. 6, the oil separator may have a housing in the shape of a rectangular parallelepiped. The housing includes a case 170 having an opening and a cover 171 that seals the opening of the case 170. The case 170 has an intake port 172 and an exhaust port 173. A drain outlet (not shown) for discharging drain liquid is provided at the bottom of the case 170. A partition wall 181 having a hole 182 is provided inside the case 170, and the partition wall 181 divides the case 170 into a first expansion chamber 183 on the intake port 172 side and a second expansion chamber 184 on the exhaust port 173 side. The partition wall 181 also has a communication hole 185 that allows drain liquid to pass between the first expansion chamber 183 and the second expansion chamber 184. A pair of collision plates 186, 187 are provided on both sides of the partition wall 181. Slits 188 and 189 are formed in the collision plates 186 and 187, respectively. Furthermore, communication holes 191 and 192 that allow the drain liquid to pass through are formed at the lower ends of the collision plates 186 and 187, respectively. Furthermore, a filter 194 is installed upstream of the collision plates 186 and 187 in the first expansion chamber 183. The filter 194 is made of the same material as the filter 42 in the above embodiment, and a perforated plate 193 with a plurality of holes is provided on the surface opposite to the intake port 172. Furthermore, a filter 197 with perforated plates 195 and 196 with a plurality of holes attached to both sides is installed downstream of the collision plates 186 and 187 in the second expansion chamber 184. It is preferable that the opening area of the perforated plate 195 in the front stage is larger than the opening area of the perforated plate 196 in the rear stage. The filter outlet is a plurality of ventilation holes 198 formed in the perforated plate 196 on the exhaust port 173 side, and the opening area of the filter outlet is the total area of all the ventilation holes 198. The opening area of the exhaust port 173 is larger than the opening area of the filter outlet (all the ventilation holes 198). In this way, since the opening area of the exhaust port 173 is larger than the opening area of the filter outlet, the flow speed of the clean air decreases at least when the clean air flows from the filter outlet toward the exhaust port 173. Therefore, the exhaust sound of the clean air can be reduced. In addition, the perforated plate 195 can straighten the clean air and reduce the exhaust sound associated with turbulence.

The housing of the oil separator 5 may be configured other than a body, a drain bowl and a filter case, or a case and a lid. For example, it may be configured with a drain bowl provided with an intake port and an exhaust port, and a lid that closes the opening of the drain bowl.

- In the above embodiment and other embodiments, the drain liquid contained in the purge air sent from the air dryer 2 is removed by the oil separator 5, and the oil and moisture contained in the compressed air sent from the compressor 1 is removed by the oil separator 5. However, other embodiments are also possible. That is, the oil separator 5 may be connected to a device other than the compressor that discharges gas containing oil, and may remove the oil discharged from that device.

- The filter section 40 may have a configuration other than that of the filter 42 made of the above-mentioned material, so long as it is capable of separating gas and liquid from compressed air. For example, it may have a configuration in which a baffle plate is provided inside the filter case 41, or it may have a configuration in which gas and liquid are separated by colliding compressed air against the baffle plate.

- In the above embodiment and other embodiments, the oil separator 5 is applied to a compressed air drying system mounted on a vehicle (automobile), but it may be applied to other systems as long as the system has a function for separating air (gas) containing oil into gas and liquid. For example, the oil separator may be applied to moving bodies other than automobiles, such as trains, ships, and aircraft. The oil separator may also be applied to pneumatic systems other than moving bodies.

- In the above embodiment, the depth L2 of the second through hole 64 is greater than the diameter D2. This is expected to have the effect of straightening the compressed air and reducing noise. Similarly, the depth of the ventilation hole 58 of the filter outlet 57 may be greater than its diameter D1. Also, the depth of the first through hole 63 of the first porous plate 61 may be greater than its diameter D2. This is also expected to have the effect of straightening the compressed air and reducing noise.

1...Compressor, 2...Air dryer, 2a...Desiccant, 2b...Exhaust valve, 2c...Drain outlet, 2d...Connection hose, 5...Oil separator, 6...System tank, 10...Body, 11...Opening, 12...Female screw, 13...Annular protrusion, 14...Female screw, 16...Intake port, 17...Exhaust port, 18...First passage, 19...Second passage, 21...Small passage, 22...Small passage, 23...Second expansion chamber, 25...Step, 26...Groove, 30...Drain bowl , 31...opening, 32...storage section, 33...male screw, 34...first expansion chamber, 40...filter section, 41...filter case, 42...filter, 43...filter cover, 44...discharge hole, 51...annular protrusion, 52...male screw, 53...ceiling section, 54...opening, 55...peripheral wall section, 56...first vent hole, 57...filter outlet, 58...vent hole, 61...first porous plate, 62...second porous plate, 63...first through hole, 64...second through hole, 65...silencer, 66...retainer ring.

Claims (4)

a housing provided with an intake port into which compressed air flows and an exhaust port from which clean air is discharged, and configured to cause the compressed air that flows in horizontally from the intake port to flow vertically downward;
A filter unit that separates the compressed air into gas and liquid;
a reservoir provided below the filter and configured to retain the liquid separated by the filter ;
a sound -absorbing section having a large number of pores through which the compressed air passes, the sound-absorbing section reducing exhaust noise by passing the compressed air that has passed through the filter section through the pores, and sending the compressed air to the exhaust port side as the clean air,
The sound absorbing part is
A first porous plate having a plurality of through holes;
A porous material having a large number of pores through which compressed air passes;
A second porous plate having a plurality of through holes;
a fall-off prevention member fixed to the housing side, the fall-off prevention member being provided in order along a direction from the filter portion toward the exhaust port of the exhaust port,
an expansion chamber for expanding the clean air is provided between a filter outlet through which the clean air that has passed through the filter unit flows out and the first porous plate;
The filter outlet of the filter unit passes clean air along a first direction parallel to a vertical direction, and the first porous plate passes clean air along a second direction perpendicular to the first direction,
The first porous plate, the porous material, and the second porous plate are restricted from moving toward the exhaust port by the anti-removal member that fits into a groove formed in an exhaust port side passage of the exhaust port in the housing,
The first porous plate is provided between a step portion provided in an exhaust port side passage of the exhaust port in the housing and the porous material,
An oil separator, wherein the exhaust port outlet has a diameter greater than a diameter of the intake port inlet. The oil separator according to claim 1 , wherein the intake port and the exhaust port extend horizontally in a state where the storage portion is disposed vertically downward. The filter unit is provided with an inlet for introducing the compressed air and an outlet for discharging the compressed air that has passed through the filter unit,
2. The oil separator according to claim 1, wherein a porous member having through holes is provided in a passage including from the outlet to the exhaust port, and an opening area of the porous member is larger than an opening area of the outlet. an air dryer that performs a load operation for removing oil and moisture from compressed air and an unload operation for discharging the removed oil and moisture from an exhaust port;
an oil separator connected to an outlet of the air dryer;
The oil separator comprises:
a housing provided with an intake port into which compressed air flows and an exhaust port from which clean air is discharged, and configured to cause the compressed air that flows in horizontally from the intake port to flow vertically downward;
A filter unit that separates the compressed air into gas and liquid;
a reservoir provided below the filter and configured to retain the liquid separated by the filter ;
a sound -absorbing section having a large number of pores through which the compressed air passes, the sound-absorbing section reducing exhaust noise by passing the compressed air that has passed through the filter section through the pores, and sending the compressed air to the exhaust port side as the clean air,
The sound absorbing part is
A first porous plate having a plurality of through holes;
A porous material having a large number of pores through which compressed air passes;
A second porous plate having a plurality of through holes;
a fall-off prevention member fixed to the housing side, the fall-off prevention member being provided in order along a direction from the filter portion toward the exhaust port of the exhaust port,
an expansion chamber for expanding the clean air is provided between a filter outlet through which the clean air that has passed through the filter unit flows out and the first porous plate;
The filter outlet of the filter unit passes clean air along a first direction parallel to a vertical direction, and the first porous plate passes clean air along a second direction perpendicular to the first direction,
The first porous plate, the porous material, and the second porous plate are restricted from moving toward the exhaust port by the anti-removal member that fits into a groove formed in an exhaust port side passage of the exhaust port in the housing,
The first porous plate is provided between a step portion provided in an exhaust port side passage of the exhaust port in the housing and the porous material,
A compressed air drying system, wherein the exhaust port outlet has a diameter greater than a diameter of the intake port inlet.