JPH10141260A - Oil circulating-type mechanical pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil circulating-type mechanical pump capable of well maintaining the seal effect of the mechanical pump, keeping the specified degree of vacuum, coping with corrosive gas, and securing the normal operation of the pump. SOLUTION: Gas and oil to be discharged from a discharge port a8 of a screw pump A as an oil circulating-type mechanical pump are introduced into an oil trap B, and oil is separated from discharge gas by filters b6, b7. This separated oil is introduced into deaeration chambers T1, T2 through flow control valves c5, c6. Both deaeration chambers T1, T2 are connected to a deaerating vacuum pump RP through flow control valves c7, c8, bubbles in oil are removed by the negative pressure action and fed out from the lower parts of both chambers through flow control valves c9, c10 by an oil circulating pump P, and oil is again poured into an oil poring port a10 of the screw pump A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil circulation type mechanical pump in which oil is injected into a rotor portion, the pump is maintained at a predetermined temperature by the oil, and a sealing effect is enhanced.

[0002]

2. Description of the Related Art Among mechanical pumps, for example, a screw pump generally has a plurality of spiral land portions and grooves, and a pair of screw members rotating about two substantially parallel axes while meshing with each other. A rotor is provided, and a suction port and a discharge port are formed in a casing that houses the rotors.

[0003] There has also been proposed one in which oil is injected into a screw rotor portion, and the oil is used to enhance the cooling and sealing effects. FIG. 7 shows an example of an oil circulation type screw pump disclosed in, for example, JP-A-2-259295. That is, the example shown in FIG. 7 is configured such that oil is supplied via an oil cooler 34 to a screw pump main body 33 in which a suction port 31 and a discharge port 32 are formed.

[0004] An oil separation / collection tank 35 is connected to the discharge port 32 of the screw pump main body 33. The gas is naturally separated to the lower bottom, and the discharged gas is discharged to the atmosphere from a discharge pipe 36 connected to the upper part of the tank 35. Then, the oil naturally separated at the lower bottom of the tank 35 is cooled by the oil cooler 34, and is again returned to the screw pump main body 33.
And is circulated.

In the example shown in FIG. 7, the oil supplied to the bearing portion of the screw pump body 33 is pressurized by an oil pump 38 through a second flow path 37 and passes through the oil cooler 34. It is configured as follows.

[0006]

By the way, in the conventional oil circulation type mechanical pump as described above,
The gas and oil discharged from the discharge port are used to separate oil naturally from the discharged gas by its own weight in the oil separation and recovery tank, so that a large amount of air bubbles remain in the oil and a large amount of air bubbles remain. The circulation in which the oil is again injected into the mechanical pump is repeated. For this reason, there was a technical problem that bubbles remaining in the oil hindered the sealing effect between the pair of rotors, making it impossible to obtain a predetermined degree of vacuum.

Further, the above-mentioned mechanical pump is used as a vacuum pump in, for example, a processing step (plasma etching, low-pressure vapor phase growth) for releasing a toxic gas or a corrosive gas under reduced pressure when manufacturing a semiconductor device. These gases react in the pump, etc. to corrode the components of the pump, degrade the oil, and the reaction products accumulate in the pump, etc. There was a technical problem of hindering operation.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and can maintain a good sealing effect of a mechanical pump, maintain a predetermined degree of vacuum, and prevent corrosive gas and the like. It is an object of the present invention to provide an oil circulation type mechanical pump capable of taking measures and ensuring a normal operation of the pump.

[0009]

According to the first aspect of the present invention, there is provided an oil circulation type mechanical pump according to the present invention, wherein a gas suction port and a discharge port are formed in a casing accommodating a rotor. And a mechanical pump main body having an oil injection port for injecting oil into the rotor in a part of the casing, and connected to a discharge port of the mechanical pump main body and discharged together with discharge gas. An oil trap that separates oil from the discharged gas; and a deaeration chamber that is connected to the oil trap and applies a negative pressure to the oil separated by the oil trap to remove bubbles existing in the oil. The oil degassed by the degassing chamber is again injected into an oil inlet of the mechanical pump body. Constructed.

According to a second aspect of the present invention, there is provided an oil circulation type mechanical pump according to the present invention, wherein a casing accommodating a rotor is provided with a gas suction port and a discharge port. A mechanical pump main body having an oil injection port for injecting oil into the rotor in a part of the casing; and a discharge gas connected to a discharge port of the mechanical pump main body and discharged together with the discharge gas. An oil trap connected to the oil trap, and a degassing filter connected to the oil trap to separate bubbles present in the oil from the oil separated by the oil trap through the partition film. It is configured so that the gas that has been evacuated is again injected into the oil injection port of the mechanical pump body.

Further, according to a third aspect of the present invention, there is provided an oil circulation type mechanical pump according to the present invention, wherein a casing accommodating a rotor is provided with a gas suction port and a discharge port. A mechanical pump main body having an oil injection port for injecting oil into the rotor in a part of the casing; and a discharge gas connected to a discharge port of the mechanical pump main body and discharged together with the discharge gas. An oil trap that separates more, an oil storage unit that temporarily stores oil separated from a discharge gas formed in the oil trap, and an oil that is kept in contact with the oil stored in the oil storage unit and maintains the oil at a predetermined temperature. And a predetermined temperature maintaining unit for controlling the temperature of the mechanical pump body from 100 ° C. to 2 ° C.
It is configured to be maintained within the range of 00 ° C.

In the above-mentioned oil circulation type mechanical pump, it is desirable that an oil inlet formed in a casing accommodating the rotor is located on a side surface of the rotor.

Further, the deaeration chamber in the mechanical pump of the first embodiment according to the present invention preferably comprises a first chamber and a second chamber respectively connected to an oil trap. Alternatively, a negative pressure is applied to the second chamber to remove bubbles present in the oil, and the oil stored in the degassed chamber is injected into an oil inlet of the mechanical pump body. It is composed of

Further, in the oil traps according to the first and second aspects of the present invention, an oil storage portion for temporarily storing oil separated from the discharged gas is formed, and the oil stored in the oil storage portion is formed. It is preferable to arrange a predetermined temperature maintenance unit for maintaining the oil at a predetermined temperature in contact with the unit.

In this case, the oil circulation type mechanical pump according to the present invention is configured such that an inert gas is injected into at least a suction port and a discharge port formed in a casing of the mechanical pump body. , The surface of the member that comes into contact with the corrosive gas is FeF ₂ , Cr
It is desirable that the surface treatment of F ₃ have been made.

It is desirable that the oil circulation type mechanical pump according to the present invention be installed so that the rotor is substantially vertical.

According to the oil circulation type mechanical pump of the first embodiment configured as described above, the oil separated by the oil trap is further introduced into the deaeration chamber, and a negative pressure is applied in the deaeration chamber. Because
Bubbles present in the oil are forcibly removed. Further, according to the oil circulation type mechanical pump of the second embodiment configured as described above, the oil separated by the oil trap is further introduced into the degassing filter, and is introduced into the oil through the partition membrane in the degassing filter. Any bubbles present are forcibly removed. Therefore, in any of the modes, the oil containing air bubbles does not circulate in the mechanical pump, the sealing effect of the rotor is guaranteed, and the pump can obtain a predetermined degree of vacuum.

According to the oil circulation type mechanical pump of the third embodiment configured as described above, since the predetermined temperature maintaining unit is provided, the temperature of the mechanical pump main body is maintained within the range of 100 ° C. to 200 ° C. Because
A chemical reaction inside the mechanical pump can be suppressed, and generation of a reaction product can be prevented. Therefore,
Since accumulation of reaction products is suppressed, normal operation of the pump can be guaranteed for a long time. Here, in order to suppress a chemical reaction inside the mechanical pump, it is preferable to maintain the temperature of the mechanical pump body at a high temperature of 100 ° C. or higher. On the other hand, in order to maintain the performance of the pump such as the sealing property of the mechanical pump, it is preferable to maintain the temperature at 200 ° C. or lower. Therefore, it is preferable to maintain the temperature of the mechanical pump main body within the range of 100 ° C. to 200 ° C., and it is more preferable to maintain the temperature of the mechanical pump main body at approximately 150 ° C.

Further, by arranging the oil inlet formed in the casing accommodating the rotor at the side of the rotor, the oil scatters toward the suction port side of the pump.
For example, it is possible to prevent problems such as contamination of a low-pressure vapor deposition apparatus for manufacturing a semiconductor element. In particular, by forming the oil injection port substantially in the middle of the rotor rotation shaft, the above-described effect can be obtained. Further, by configuring the deaeration chamber by the first chamber and the second chamber, the deaeration step of the oil can be alternately performed and the continuous operation of the mechanical pump can be guaranteed.

The oil trap is provided with a temperature maintaining unit for maintaining the oil at a predetermined temperature. The temperature maintaining unit can maintain the oil separated from the discharged gas at a constant temperature. By maintaining the oil at a constant temperature in this way, it is possible to prevent the temperature of the pump from rising more than necessary and to prevent the generation of reaction products due to exhaust gas.

Further, since the inert gas is injected into the casing, measures against corrosive gas and the like can be taken, and the reliability of the pump can be improved. Further, the surface of the member that comes into contact with the corrosive gas is
Since eF ₂ and CrF ₃ are surface-treated, corrosion can be prevented and the reliability of the pump can be improved.

Since the rotor is installed so as to be substantially vertical, oil scatters on the suction port side of the pump, and contaminates, for example, a low pressure vapor deposition apparatus for manufacturing semiconductor devices. Can be prevented from occurring.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an oil circulation type mechanical pump according to the present invention will be described based on an embodiment shown in the drawings. In describing this embodiment,
A screw pump will be described as an example. The same or corresponding portions in the respective drawings described below are denoted by the same reference numerals, and therefore, detailed description thereof will be omitted as appropriate. First, FIG.
Is shown in a sectional view. The screw pump body A has a plurality of spiral land portions and grooves,
A pair of screw rotors a1 (a2) rotating about two substantially parallel axes while meshing with each other is provided. In FIG. 1, one screw rotor a2 is not illustrated because it is positioned in a direction perpendicular to the plane of the drawing.

The screw rotor a1 (a2)
The screw rotor a1 is stored in the casing a3.
Both ends of a shaft a4 supporting (a2) are rotatably supported by bearings a5. A timing gear a6 is attached to one end of the shaft a4, and a pair of screw rotors a1 (a2) is configured to be synchronously rotated via the timing gear a6.

A casing a3 accommodating both rotors a1 (a2) is formed with a suction port a7 at one end and a discharge port a8 at the other end of the casing a3. , The screw rotor a
1 (a2) is configured to rotate in synchronization with each other so that a function of a vacuum pump for sucking gas from the suction port a7 and exhausting gas from the discharge port a8 is performed.

On the discharge port a8 side of the casing a3, there is formed a jacket a9 having a hollow portion through which cooling water can be circulated.
It is configured such that the heat generated by the gas based on the compression action on the side 8 can be cooled. Further, an oil injection port a10 is formed in a part of the casing at a substantially central portion in the rotation axis direction of the screw rotor, and oil injected from the oil injection port a10 is used for a pair of screw rotors a1 ( a2), it acts to seal between the two, and also has the effect of maintaining the pump at a predetermined temperature.

In this case, since the oil inlet is located on the side surface of the screw rotor, the degree of splashing of oil to the suction port a7 side is reduced, and for example, a semiconductor connected to the suction port a7 side The sealing effect is exerted on the screw rotor portion on the side of the discharge port a8 to which atmospheric pressure is applied without contaminating the vapor phase growth apparatus for manufacturing the element. The two rotors a
Covers a11 and a12 are attached to both ends of a casing a3 that accommodates the casing 1 (a2). Oil reservoirs a13 and a14 are formed between the covers a11 and a12 and the end of the casing a3. The lubricating action of the oil is performed on the bearing portion of the shaft a4 that supports the screw rotor a1 (a2). One of the shafts a4 that supports one screw rotor a1 protrudes from the cover a11 and is configured to be directly connected to a rotating shaft of a motor described later.

FIG. 2 shows the screw pump body A described above.
1 shows a first embodiment of the present invention using the above. The screw pump main body A shown in FIG. 1 is simply indicated by one block A in FIG. The oil injection port a10 and the oil pipe connected to the oil pump port A10, the discharge port a8, the discharge pipe connected to the discharge port a8, and the water pipe connected to the cooling jacket a9 are arranged in the screw pump body A. Are simply represented by a single solid line.

In FIG. 2, a driving motor M is disposed in the screw pump main body A, and a shaft a for supporting the screw rotor a1 by driving the motor M is provided.
4 is driven to rotate, and the screw pump main body A is configured to function as a vacuum pump. A discharge pipe a connected to a discharge port a8 of the screw pump body A
21 is connected to the oil trap B. The outer periphery of the oil trap B is formed by a single housing, and the oil discharged together with the discharge gas from the screw pump main body A by the operation of the screw pump main body A is introduced into the upper chamber b1 of the oil trap B. Is done.

Here, hatched portions b6 and b7 in the drawing indicate filters, and the filters b7 are formed in an annular shape.
It separates and recovers oil from gas.
b6 is formed in a disk shape and removes impurities such as reaction products contained in the oil. Also in the figure b
Reference numerals 8 and b9 denote an oil mist portion and an oil return portion. The oil mist portion b8 is formed on the back surface of the filter b7, and allows the oil passing through the filter b7 to pass through the upper chamber b.
It is for returning to 1. Furthermore, oil trap B
Here, the oil is separated and recovered from the gas, and the recovered oil is temporarily stored in the lower chamber b2 as an oil storage unit. Further, the discharge gas is configured to be led out to the atmosphere or a gas processing device from a discharge pipe b4 arranged in the upper chamber b1 of the oil trap B.

On the other hand, the lower chamber b2 in the oil trap B
Is provided with a cooling unit b3 which is a temperature maintaining unit composed of a U-shaped tube for keeping the oil at a predetermined temperature in contact with the stored oil. This cooling unit b
3, cooling water cooled by a cooling facility (not shown) is sent through the flow control valves c1 and c2, and an oil trap is provided by the cooling water passing through the cooling unit b3. The oil stored in the lower chamber b2 of B is cooled. The cooling water is supplied to the flow control valves c3 and c4.
Through the cooling jacket a9 of the screw pump body A
The water is also supplied to the screw pump main body A, so that the screw pump body A is cooled particularly around the discharge port a8. By maintaining the oil at a constant temperature in this manner, it is possible to prevent the temperature of the pump from rising more than necessary and to prevent the generation of reaction products due to exhaust gas.

The oil separated by the oil trap B is introduced into the degassing chamber T. The deaeration chamber includes a first chamber T1 and a second chamber T2 connected to the oil trap B via flow control valves c5 and c6, respectively. The first chamber T1 and the second chamber T2 are connected to each other. The flow control valves c5 and c6 connected to the chamber T2 are controlled by a sequencer (not shown) so as to be opened alternatively.

For convenience of explanation, for example, the first chamber T1
If the flow control valve c5 on the side of the second chamber T2 is open, the flow control valve c6 on the side of the second chamber T2 will be in the closed state, and the oil from the oil trap B will of course be removed from the first chamber T2.
Introduced in 1. A vacuum pump RP for deaeration is connected to the first chamber T1 and the second chamber T2 via flow control valves c7 and c8, respectively. The flow control valves c7, c8 provided in the first chamber T1 and the second chamber T2 are alternatively opened, so that the first chamber T1 or the second chamber T2 is selectively negative. Pressure is applied.

When oil is introduced into the first chamber T1, a negative pressure is applied to the second chamber T2 under the control of the sequencer, and therefore, the oil is stored in the second chamber T2. Air bubbles existing in the oil thus removed are sucked by the negative pressure, and the vacuum pump R for deaeration is used.
P is released to the atmosphere through the discharge pipe RP1 by the action of P.

An oil feed pipe extends from the lower bottom of the first chamber T1 and the second chamber T2, and is connected to an oil circulation pump P via flow control valves c9 and c10. Further, the oil sent by the oil circulation pump P is configured to be injected into the oil injection port a10 of the screw pump main body A via the variable valve d1. Here, the flow rate control valves c9 and c10 provided in the oil feed pipe are controlled by the sequencer so as to discharge the oil on the chamber side degassed by the negative pressure,
In the above case, the oil stored in the second chamber T2 is injected into the oil injection port a10 of the screw pump body A by the pump P. Although not shown in the drawing, the tank is configured so that an inert gas is introduced from a tank storing an inert gas such as a nitrogen gas (N ₂ ) into each of the parts described below. I have.

That is, the inert gas is supplied to the flow control valves c11 and c11.
12 are introduced into the two chambers T1 and T2, respectively, and dilute corrosive gas and the like sucked from oil in the chambers T1 and T2 to prevent corrosion of the chambers T1 and T2 and piping connected thereto. It is done as follows. Further, the inert gas is introduced into the suction port a7 of the screw pump body A via the variable valve d2,
It functions to dilute corrosive gas and the like introduced into the casing a3 of the screw pump main body A from the suction port a7, and to prevent corrosion in the screw pump main body A and deterioration of oil.

Further, the gas is introduced into the discharge pipe b4 arranged in the oil trap B and the discharge pipe RP1 arranged in the vacuum pump RP for deaeration via the variable valves d3 and d4, respectively. By introducing an inert gas into the discharge pipe b5 disposed in the oil trap B and the discharge pipe RP1 disposed in the deaeration vacuum pump RP, the screw pump A is stopped or the deaeration vacuum pump RP is activated. In the event of an accident such as a stop, air containing moisture from the outside is prevented from entering the pump and corroding the components of the pump. That is, the oil trap B and the vacuum pump R
It shuts off the inside and the outside of P, and acts to prevent the moisture in the air from reacting with the corrosive gas to prevent the parts from being corroded.

During the operation of the screw pump A and the operation of the deaeration vacuum pump RP, the pressure in the oil trap and the discharge pipe RP1 can be increased to a pressure higher than the atmospheric pressure by introducing an inert gas. In addition, an inert gas flow is created in the discharge port, and air (moisture) from outside
Can be prevented from entering. As a result, it is possible to prevent the moisture in the air from reacting with the exhaust gas to generate corrosive gas, prevent the oil from deteriorating, and prevent the generation of fine powder of the reaction product.

FIG. 3 shows a second embodiment of the present invention. In the example shown in FIG. 3, a deaeration filter T for separating bubbles present in oil through a partition wall film is used instead of the deaeration chamber T for removing bubbles by a negative pressure. The configuration is the same as that shown in FIG. In the embodiment shown in FIG. 3, the oil stored in the oil trap B is sent to the degassing filter F by the oil circulation pump P, and the oil degassed by the degassing filter F is passed through the variable valve d1. It is configured so that the oil is again injected into the oil injection port a10 of the screw pump body A.

FIG. 4 shows the structure of the deaeration filter F. A housing f1 constituting an outer shell of the degassing filter F
Is formed in a cylindrical shape so that oil is conducted from the longitudinal end to the other end. A large number of hollow fibers f2 are arranged inside a cylindrical housing f1, and oil passes through each of the hollow fibers f2. The outer wall surface side of the hollow fiber f2 is sucked by the vacuum pump RP for deaeration and a negative pressure is applied, and bubbles in the oil are separated from the outer wall surface of the fiber f2 via the partition wall film as the fiber f2. Is sucked.

The partition wall film f2 can be classified into a porous film, a non-porous film, a coated composite film, and the like according to its manufacturing method. Hollow fiber material (poly 4-methylpentene 1) can be used. According to the configuration shown in FIG. 3 and FIG.
Equipment such as a flow control valve for controlling the two chambers T1 and T2 and negative pressure for each of the chambers, and a sequencer for controlling release and closing of the flow control valve can be eliminated, thereby simplifying the configuration. Can be.

As the screw pump in the above embodiment, a so-called vertical pump is preferably used as shown in FIG. In FIG. 5, the same or corresponding members as those shown in FIGS. 1 and 2 are denoted by the same reference numerals. The so-called vertical pump shown in FIG. 5 is installed so that the rotation axes of the screw rotors a3 and a1 are substantially vertical as shown in the figure, so that the oil mainly flows to the discharge port a8 side, The sealing property on the discharge side is further improved. By the way, in a horizontal screw pump as shown in FIG.
Since the oil flows to the suction side at the time of stop, the oil is scattered by the centrifugal force when re-operation is performed, which may adversely affect the chamber and the like. However, as shown in FIG. 5, the vertical pump is installed so that the rotation axes of the screw rotors a3 and a1 are substantially vertical, so that the oil flows to the discharge side when the pump is stopped, and when the pump is restarted. Oil is centrifugal and suction port a
It does not scatter to the side 7 and does not adversely affect the chamber and the like.

FIG. 6 shows a third embodiment of the present invention. As shown in FIG. 6, in this embodiment, a predetermined temperature for maintaining the oil at a predetermined temperature is provided in an oil storage portion b2 for temporarily storing oil separated from a discharge gas formed in the oil trap B. It is characterized in that a maintenance unit is provided. That is, a heater H is provided to maintain the temperature of the mechanical pump body within a range of 100 ° C. to 200 ° C., and the temperature of the oil is controlled to a predetermined temperature. Since the mechanical pump is maintained in the predetermined temperature range, a chemical reaction inside the mechanical pump can be suppressed, and generation of a reaction product can be prevented. Therefore, since the accumulation of the reaction product is suppressed, the normal operation of the pump can be guaranteed for a long time.

Further, the cooling unit b3 provided in the first and second embodiments of the present invention is also provided, and both the heater H and the cooling unit b3 are controlled to reduce the temperature of the mechanical pump body. The temperature may be maintained in the range of 100 ° C to 200 ° C. That is, when the temperature of the mechanical pump body is 1
When the temperature exceeds 50 ° C., the cooling unit b3 is operated,
When the temperature is lower than 150 ° C., the temperature of the mechanical pump body is raised to 100 ° C. to 20 ° C.
The temperature may be maintained within the range of 0 ° C.

Further, the temperature of the mechanical pump body is controlled by controlling the cooling water supplied to the cooling jacket a9 provided in the first and second embodiments of the present invention.
The temperature may be maintained in the range of 0 ° C to 200 ° C.

The surfaces of members that come into contact with corrosive gas, such as the screw rotors a1, a2, the casing a3, and the inside of the oil trap B of the screw pump A, are made of FeF ₂ , C
Surface treatment of rF ₃ has been performed. This surface treatment is carried out by subjecting the surface of the component
Made by forming a _2, CrF ₃ of fluoride passivated film. Since such a surface treatment is performed, it is possible to prevent corrosion of the member that comes into contact with the corrosive gas.

Although the above embodiment has been described using a screw pump, the present invention is not limited to this, and can be applied to a mechanical pump such as a root pump.

[0048]

As apparent from the above description, according to the oil circulation type mechanical pump of the present invention, an oil trap for separating oil discharged together with the discharged gas from the discharged gas, and an oil trap connected to the oil trap. A degassing chamber for applying a negative pressure to the oil separated by the oil trap to remove bubbles present in the oil, or a degassing filter for separating bubbles present in the oil from the oil via the partition wall film , Air bubbles existing in the oil are forcibly removed. Therefore, the oil containing air bubbles does not circulate in the mechanical pump, the sealing effect of the rotor is guaranteed, and the pump can obtain a predetermined degree of vacuum.

Further, according to the oil circulation type mechanical pump of the present invention, since the oil circulation type mechanical pump is provided with the predetermined temperature maintaining unit, the temperature of the mechanical pump main body is set to 100 ° C. to 20 ° C.
Since the temperature is maintained within the range of 0 ° C., a chemical reaction inside the mechanical pump can be suppressed, and generation of a reaction product can be prevented. Therefore, since the accumulation of the reaction product is suppressed, the normal operation of the pump can be guaranteed for a long time.

Further, by arranging the oil inlet formed in the casing accommodating the rotor at the side of the rotor, the oil scatters toward the suction port side of the pump.
For example, it is possible to prevent problems such as contamination of a low-pressure vapor deposition apparatus for manufacturing a semiconductor element.

Further, by forming the degassing chamber by the first chamber and the second chamber, the oil degassing process can be alternately performed, and continuous operation of the mechanical pump can be guaranteed. it can. Also,
By maintaining the oil at a predetermined temperature by the oil trap, the temperature inside the pump can be maintained at the predetermined temperature. As a result, the reaction by the corrosive gas can be suppressed, and the generation of the reaction product can be suppressed.

If the inert gas is injected into the casing, measures against corrosive gas and the like can be taken, and the reliability of the pump can be improved.
Further, since the rotation axis of the rotor is set to be substantially vertical, the oil does not scatter to the suction port side due to centrifugal force, and does not adversely affect the chamber and the like. Further, the surface of the member that comes into contact with the corrosive gas is made of FeF ₂ , Cr
Since the surface treatment of F ₃ have been made, it is possible to prevent corrosion of the member in contact with the corrosive gas.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a screw pump main body according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a first embodiment according to the present invention using the screw pump shown in FIG.

FIG. 3 is a block diagram showing a second embodiment according to the present invention using the screw pump shown in FIG. 1;

FIG. 4 is a sectional view showing a configuration of a degassing filter used in the embodiment shown in FIG.

FIG. 5 is a side sectional view showing a vertical screw pump.

FIG. 6 is a block diagram showing a third embodiment according to the present invention using the screw pump shown in FIG. 1;

FIG. 7 is a block diagram showing an example of a conventional oil circulation type screw pump.

[Explanation of symbols]

 A Screw pump body a1, a2 Screw rotor a3 Casing a7 Suction port a8 Discharge port a10 Oil inlet B Oil trap b1 Upper chamber b2 Lower chamber (oil storage part) b3 Cooling unit F Deaeration filter f2 Fiber (partition membrane) M Drive Motor P Oil circulation pump RP Vacuum pump for deaeration T Deaeration chamber T1 First chamber T2 Second chamber H Heater

Claims (9)

[Claims] 1. A mechanical pump in which a casing containing a rotor is formed with a gas intake port and a discharge port, and an oil inlet for injecting oil into the rotor is formed in a part of the casing. A main body, an oil trap connected to a discharge port of the mechanical pump main body, for separating oil discharged together with the discharge gas from the discharge gas, and a negative pressure for the oil separated by the oil trap connected to the oil trap. And a degassing chamber for removing air bubbles present in the oil by applying pressure, and the oil degassed by the degassing chamber is injected again into an oil inlet of the mechanical pump body. Oil circulation type mechanical pump characterized by the following. 2. A mechanical pump having a casing in which a rotor is housed, and a gas suction port and a discharge port formed therein, and an oil inlet for injecting oil into the rotor is formed in a part of the casing. A main body, an oil trap connected to a discharge port of the mechanical pump main body, for separating oil discharged together with the discharge gas from the discharge gas, and an oil trap connected to the oil trap, and separated from the oil trap by the oil trap via a partition membrane. A deaeration filter for separating air bubbles present in the oil, and configured to re-inject the oil deaerated by the deaeration filter into an oil inlet of the mechanical pump body. Oil circulation type mechanical pump. 3. A mechanical pump having a casing in which a rotor is accommodated, a gas intake port and a discharge port formed therein, and an oil inlet for injecting oil into the rotor is formed in a part of the casing. A main body, an oil trap connected to a discharge port of the mechanical pump main body, for separating oil discharged together with the discharge gas from the discharge gas, and temporarily storing oil separated from the discharge gas formed in the oil trap. And a predetermined temperature maintaining unit for maintaining the oil at a predetermined temperature in contact with the oil stored in the oil storage section, and controlling the temperature of the mechanical pump body to 100 ° C.
An oil circulation type mechanical pump, which is maintained at a temperature within a range from 200 to 200 ° C. 4. An oil injection port formed in a casing accommodating a rotor, wherein the oil injection port is located on a side surface of the rotor. Oil circulation type mechanical pump. 5. The deaeration chamber includes a first chamber and a second chamber connected to an oil trap, respectively, and a negative pressure is selectively applied to the first chamber and the second chamber. And applying air to the mechanical pump body to remove bubbles present in the oil and to allow the oil stored in the degassed chamber to be injected into an oil inlet of the mechanical pump body. The described oil circulation mechanical pump. 6. The oil trap is provided with an oil storage portion for temporarily storing oil separated from a discharge gas, and is in contact with the oil stored in the oil storage portion to maintain the oil at a predetermined temperature. Wherein a predetermined temperature maintaining unit is disposed.
The oil circulation type mechanical pump according to any one of claims 4 and 5. 7. The system according to claim 1, wherein an inert gas is injected into at least a suction port and a discharge port formed in a casing of the mechanical pump body. The oil circulation type mechanical pump according to the item. 8. The surface of a member that comes into contact with a corrosive gas is made of FeF
_2, oil circulation type mechanical pump as claimed in any one of claims 1 to 7, characterized in that the surface treatment of CrF ₃ have been made. 9. The oil circulation type mechanical pump according to claim 1, wherein the rotor is installed so as to be substantially vertical.