JP6842148B2 - Multi-stage roots vacuum pump device - Google Patents

Description

The present invention relates to a multi-stage roots vacuum pump device.

As a type of multi-stage roots type vacuum pump, Japanese Patent Application Laid-Open No. 2010-203422 describes that a suction port, a discharge port and a plurality of vacuum chambers are formed in a casing, and a pair of three-leaf roots rotors can be rotated in each vacuum chamber. A multi-stage roots vacuum pump housed in is disclosed.
In this multi-stage roots type vacuum pump, bearings that support the rotating shaft of a three-leaf type roots rotor that penetrates the vacuum chamber are built in the housing assembled on both the left and right sides of the casing. A shaft seal portion that blocks the flow of air between the vacuum chamber and the bearing is provided close to the bearing.

By the way, when a multi-stage roots vacuum pump is used for vacuum drying after cleaning a machined part or as a vacuum source for a dehydrator, moisture is sucked into a vacuum chamber together with air from a suction port. As a result, the sucked water is trapped in the minute gap surrounded by the top of one roots rotor and the valley of the other roots rotor, causing an abnormally high pressure "liquid squeeze" phenomenon, which is the cause of the abnormality. Sound (liquid rattling noise) or abnormal vibration may occur during the operation of the vacuum pump.
When the liquid squeeze phenomenon occurs, moisture invades the shaft seal of the housing vigorously to wash away the lubricating oil of the bearing, or mix it with the lubricating oil to lubricate the bearing and the timing gear fixed to the rotating shaft. It causes defects and shortens the pump life.

In the conventional multi-stage roots vacuum pump described above, an oil seal is fitted on the inner peripheral surface of the housing near the vacuum chamber, a collar is fitted on the part near the bearing, and moisture is contained between the collar and the bearing. A swing-off ring is arranged and fixed to the rotating shaft, and a labyrinth seal is formed in the gap formed on the facing surface between the collar and the ring.
As described above, in the conventional multi-stage roots type vacuum pump, the shaft sealing portion is formed by the oil seal, the collar, and the moisture swinging ring, and a passage for returning the housing drain collected in the shaft sealing portion to the vacuum chamber is formed.

Japanese Unexamined Patent Publication No. 2010-203422

According to the conventional vacuum pump described above, the housing drain that has entered the shaft seal is returned to the vacuum chamber through the passage, but since there is no sealing mechanism between the passage and the bearing, a part of the housing drain enters the bearing. May be mixed with the lubricating oil.
In view of such a problem, it is an object of the present invention to provide a multi-stage roots type vacuum pump device capable of preventing a housing drain that has entered the shaft sealing portion from entering the bearing.

The invention according to claim 1 is fixed to a casing forming a plurality of vacuum chambers which are sequentially communicated by a suction port, a discharge port, and a passage, and a rotating shaft penetrating each vacuum chamber so as to be rotatable in the vacuum chamber. A pair of stowed three-leaf roots rotors, a pair of left and right housings that are assembled on the left and right sides of the casing and contain bearings that support the rotating shaft, and air between the vacuum chamber and the bearings that are provided close to the bearings. Equipped with a shaft seal that blocks the flow of
It is a multi-stage roots type vacuum pump device that rotates a pair of roots rotors stored in a vacuum chamber so that the suction port and the discharge port do not communicate with each other and discharges the air sucked from the suction port from the discharge port.
The first oil seal is fitted to the part of the inner peripheral surface of the housing close to the vacuum chamber, the collar is fitted to the part close to the bearing, and the second oil seal is locked to the collar.
The shaft seal part is divided by the first oil seal and the second oil seal,
Two upper and lower housing drain communication holes are formed in the housing to communicate the shaft seal and the outside of the housing, and nitrogen or compressed air is introduced into the shaft seal through the upper housing drain communication hole, or the shaft seal is introduced. By opening to the atmosphere, the housing drain accumulated in the shaft seal portion is discharged from the shaft seal portion to the outside of the housing through the lower housing drain communication hole .

The invention according to claim 2 is the multi-stage roots type vacuum pump device according to claim 1.
Connect the lower housing drain communication hole to the drain pot, and provide a housing drain discharge valve in the lower housing drain communication hole.
The feature is that a level meter is attached to the drain pot.

The invention according to claim 3 is the multi-stage roots type vacuum pump device according to claim 1, wherein the casing is formed with a casing drain communication hole for communicating the vacuum chamber and the outside of the casing, and the casing is formed in the casing drain communication hole. It is characterized by having a drain discharge valve.

According to the invention of claim 1, the shaft seal is sealed by introducing an inert gas such as nitrogen or compressed air into the shaft seal through the upper housing drain communication hole, or by opening the shaft seal to the atmosphere. The housing drain accumulated in the portion can be discharged from the shaft sealing portion to the outside of the housing through the lower housing drain communication hole. Therefore, it is possible to prevent the housing drain accumulated in the shaft sealing portion from invading the bearing, and it is possible to prevent the timing gear fixed to the bearing and the rotating shaft from being poorly lubricated and the pump life from being shortened.

According to the second aspect of the present invention, the amount of liquid in the drain pot can be checked with a level meter during the operation of the pump, the housing drain discharge valve can be opened, and the housing drain can be discharged to the drain pot in a timely manner.

According to the invention of claim 3, when the pump operation is stopped, the casing drain discharge valve is opened, the vacuum chamber is opened to the atmosphere through the casing drain discharge hole, and the drain accumulated in the vacuum chamber is discharged to the outside of the vacuum chamber. Can be done. Therefore, the amount of drain that invades the shaft seal portion can be suppressed by reducing the confinement from the time when the pump operation is stopped to the time when the operation is started.

It is a side view which shows the multi-stage roots type vacuum pump device which concerns on embodiment of this invention. It is a side sectional view which shows the multi-stage roots type vacuum pump of this apparatus. It is sectional drawing which cut from the 3-3 line of FIG. It is sectional drawing which cut from the 4-4 line of FIG. It is sectional drawing which cut from the 5-5 line of FIG. It is an enlarged sectional view which shows the shaft seal part of this apparatus.

The present invention will be described below with reference to the drawings. FIG. 1 shows a multi-stage roots vacuum pump device 10 according to an embodiment of the present invention. The multi-stage roots type vacuum pump device 10 includes a multi-stage roots type vacuum pump 11, a drive motor 12 and two drain pots 13, and a drain pot 13, a drive motor 12, and a multi-stage roots type vacuum pump 11 are placed on a base 14. They are stacked in order from.

2 to 5 show the detailed structure of the multi-stage roots vacuum pump 11. The multi-stage roots type vacuum pump 11 includes a casing 15, housings 16 and 17 assembled on both side surfaces of the casing 15, and oil covers 18 and 19 assembled to the housings 16 and 17, respectively.

The casing 15 is provided with a suction port 20 and a discharge port 21. A first vacuum chamber 22, a second vacuum chamber 23, a third vacuum chamber 24, and a fourth vacuum chamber 25 are formed inside the casing 15, and the suction port 20, the first vacuum chamber 22, the second vacuum chamber 23, and the second vacuum chamber 25 are formed. The 3 vacuum chamber 24, the 4th vacuum chamber 25, and the discharge port 21 communicate with each other through the passage 26. Further, as shown in FIG. 4, the casing 15 is formed with casing drain discharge holes 15a and 15b for communicating the vacuum chambers 22, 23, 24 and 25 with the outside, and the casings are formed in the casing drain discharge holes 15a and 15b. The drain discharge valve 58 (see FIGS. 1 and 2) is connected to the pipe.

A pair of three-leaf roots rotors 27 are rotatably stored in the first vacuum chamber 22. Similarly, a pair of three-leaf roots rotors 28 are stored in the second vacuum chamber 23, a pair of three-leaf roots rotors 29 are stored in the third vacuum chamber 24, and a pair of three-leaf roots rotors 30 are stored in the fourth vacuum chamber 25. ..

One of the three-leaf roots rotors 27 of the first vacuum chamber 22 and one of the three-leaf roots rotors 29 of the third vacuum chamber 24 are fixed to the rotating shaft 31. The other three-leaf roots rotor 27 of the first vacuum chamber 22 and the other three-leaf roots rotor 29 of the third vacuum chamber 24 are fixed to the rotating shaft 32.

One of the three-leaf roots rotor 28 of the second vacuum chamber 23 and one of the three-leaf roots rotors 30 of the fourth vacuum chamber 25 are fixed to the rotating shaft 33. The other three-leaf roots rotor 28 of the second vacuum chamber 23 and the other three-leaf roots rotor 30 of the fourth vacuum chamber 25 are fixed to the rotating shaft 34.

The rotating shaft 31 and the rotating shaft 32 penetrate the first vacuum chamber 22 and the third vacuum chamber 24, and both ends project into the housings 16 and 17, respectively. Further, the rotating shaft 33 and the rotating shaft 34 penetrate the second vacuum chamber 23 and the fourth vacuum chamber 25, and both ends project into the housings 16 and 17, respectively.

One protruding end of the rotating shaft 31 is supported by a bearing 35 built in the housing 16, and the other protruding end is supported by a bearing 36 built in the housing 17. Similarly, one protruding end of the rotating shaft 32 is supported by a bearing (not shown) built in the housing 16, and the other protruding end is supported by a bearing (not shown) built in the housing 17.

One protruding end of the rotating shaft 33 is supported by a bearing 37 built in the housing 16, and the other protruding end is supported by a bearing 38 built in the housing 17. Similarly, one protruding end of the rotating shaft 34 is supported by a bearing 39 built in the housing 16, and the other protruding end is supported by a bearing 40 built in the housing 17.

A timing gear 41 is fixed to one protruding end of the rotating shaft 31, and meshes with a timing gear (not shown) fixed to one protruding end of the rotating shaft 32.
A timing gear 42 is fixed to one protruding end of the rotating shaft 33, and meshes with a timing gear 43 fixed to one protruding end of the rotating shaft 34.

A pulley 44 is fixed to the other protruding end of the rotating shaft 31, and a pulley 45 is fixed to one protruding end of the rotating shaft 33. The pulley 44 and the pulley 45 are connected to the drive motor 12 by a V-belt 46.

As shown enlarged in FIG. 6, the housing 16 is formed with a bearing chamber 16a for accommodating the bearing 37 and a bearing chamber 16b for accommodating the bearing 39 at two locations above and below. The first oil seal 47 is fitted in a portion of the inner peripheral surface of the bearing chamber 16a close to the second vacuum chamber 23. Further, the collar 48 is fitted in a portion close to the bearing 37, and the second oil seal 49 is locked to the collar 48. A shaft sealing portion 50 that blocks the flow of air between the second vacuum chamber 23 and the bearing 37 is formed in the first oil seal 47 and the second oil seal 49. Similarly, the first oil seal 47 and the second oil seal 49 are partitioned by a shaft seal portion 50 that blocks the flow of air between the second vacuum chamber 23 and the bearing 39.

Similarly, the housing 17 is formed with bearing chambers 16c for accommodating bearings 38 and bearing chambers 16d for accommodating bearings 40 at two locations above and below. A shaft sealing portion 50 that blocks the flow of air between the fourth vacuum chamber 25 and the bearings 38 and 40 is formed in the first oil seal 47 and the second oil seal 49.

In this way, the shaft sealing portion 50 is provided in the vicinity of the bears 35, 36, 37, 38, 39, 40 that support the rotating shafts 31, 32, 33, 34. The housings 16 and 17 are formed with two upper and lower housing drain communication holes 51 and 52 that communicate the shaft sealing portion 50 and the outside of the housings 16 and 17. An inert gas introduction ball valve 53 is provided in the upper housing drain communication hole 51, and a housing drain discharge port 54 is provided in the lower housing drain communication hole 52.

As shown in FIG. 1, the housing drain discharge port 54 is connected to the drain inflow valve 55 and the drain pot pressure equalizing valve 56 of the drain pot 13 by piping. A level meter 57 and a drain discharge valve 59 are provided on the front surface of the drain pot 13.
Lubricating oil 60 is stored inside the oil covers 18 and 19 attached to the housings 16 and 17.

The structure of the multi-stage roots type vacuum pump device 10 according to this embodiment is as described above, and a part of the fluid 61 including the cleaning liquid sucked from the suction port 20 is confined and reduced to the shaft sealing portion 50 during operation. It invades and collects as a housing drain 62 between the first oil seal 47 and the second oil seal 49. Therefore, by operating the inert gas introduction ball valve 53 and introducing nitrogen or compressed air into the shaft seal portion 50 through the upper housing drain communication hole 51, or by opening the shaft seal portion 50 to the atmosphere, the shaft seal is performed. The housing drain 62 accumulated in the portion 50 is discharged from the shaft sealing portion 50 to the outside of the housings 16 and 17 through the lower housing drain communication hole 52. The discharged housing drain 62 is collected in the drain pot 13 from the drain discharge port 54.

Since a level meter 57 is attached to the drain pot 13, the amount of liquid in the drain pot 13 can be confirmed during pump operation, the drain discharge valve 59 can be opened, and the housing drain 62 can be drained from the drain pot 13 in a timely manner.

Further, the casings 16 and 17 are formed with casing drain communication holes 15a and 15b for communicating the vacuum chambers 22, 23, 24 and 25 with the outside of the casings 16 and 17, and the casings are formed in the casing drain communication holes 15a and 15b. Since the drain discharge valve 58 is provided, the casing drain discharge valve 58 is opened when the pump operation is stopped to open the vacuum chambers 22, 23, 24, 25 to the atmosphere, and the casing drain 63 collected in the vacuum chambers 22, 23, 24, 25 is provided. Can be discharged to the outside of the vacuum chambers 22, 23, 24, 25. Therefore, the amount of drain that invades the shaft sealing portion 50 can be suppressed by reducing the confinement from the time when the pump operation is stopped to the time when the operation is started.

10 ... Multi-stage roots type vacuum pump device 11 ... Multi-stage roots type vacuum pump 12 ... Drive motor 13 ... Drain pot 14 ... Base 15 ... Casing 15a, 15b ... Casinged drain discharge holes 16, 17 ... Housing 18, 19 ... Oil cover 20 ... Suction port 21 ... Discharge port 22 ... 1st vacuum chamber 23 ... 2nd vacuum chamber 24 ... 3rd vacuum chamber 25 ... 4th vacuum chamber 26 ... Passages 27, 28, 29, 30 ... Three-leaf roots rotor 31, 32, 33, 34 ... Rotating shaft 35, 36, 37, 38, 39, 40 ... Bearing 41, 42, 43 ... Timing gear 44, 45 ... Pulley 46 ... V belt 47 ... First oil seal 48 ... Color 49 ... Second oil Seal 50 ... Shaft sealing portion 51, 52 ... Communication hole for housing drain 53 ... Inactive gas introduction ball valve 54 ... Housing drain discharge port 55 ... Drain inflow valve 56 ... Drain pot pressure equalizing valve 57 ... Level meter 58 ... Casing drain discharge valve 59 ... Drain discharge valve 60 ... Lubricating oil 61 ... Fluid 62 ... Housing drain 63 ... Casing drain

Claims (3)

A pair of three-leaf type casings that form a plurality of vacuum chambers that are sequentially connected by a suction port, a discharge port, and a passage, and a pair of three-leaf type that are fixed to a rotating shaft that penetrates each vacuum chamber and are rotatably stored in the vacuum chamber. A roots rotor, a pair of left and right housings that are assembled on the left and right sides of the casing and contain bearings that support the rotating shaft, and a shaft seal that is provided close to the bearing and blocks the air flow between the vacuum chamber and the bearing. Prepare,
It is a multi-stage roots type vacuum pump device that rotates a pair of roots rotors stored in a vacuum chamber so that the suction port and the discharge port do not communicate with each other and discharges the air sucked from the suction port from the discharge port.
The first oil seal is fitted to the part of the inner peripheral surface of the housing close to the vacuum chamber, the collar is fitted to the part close to the bearing, and the second oil seal is locked to the collar.
The shaft seal part is divided by the first oil seal and the second oil seal,
Two upper and lower housing drain communication holes are formed in the housing to communicate the shaft seal and the outside of the housing, and nitrogen or compressed air is introduced into the shaft seal through the upper housing drain communication hole, or the shaft seal is introduced. A multi-stage roots type vacuum pump device characterized in that the housing drain accumulated in the shaft seal portion is discharged from the shaft seal portion to the outside of the housing through the lower housing drain communication hole by opening to the atmosphere. Connect the lower housing drain communication hole to the drain pot, and provide a housing drain discharge valve in the lower housing drain communication hole.
The multi-stage roots type vacuum pump device according to claim 1, wherein a level meter is attached to the drain pot. The multi-stage roots type vacuum pump according to claim 1, wherein a casing drain communication hole for communicating the vacuum chamber and the outside of the casing is formed in the casing, and a casing drain discharge valve is provided in the casing drain communication hole. apparatus.

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