JP2001304148A - Scroll-type vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the inert gas to be introduced into a compression chamber from flowing into a sealed case in stopping the operation in a scroll type vacuum pump capable of introducing the inert gas. SOLUTION: An introduction hole is formed on a housing for connecting a insert gas supply source and a neighborhood of a central part of a compression chamber, and a check valve opened and closed with specific pressure relationships mentioned below, is mounted inside of the introduction hole for communicating and blocking the inert gas supply source and the compression chamber. The inert gas can flow into the compression chamber 2 but not flow back in the operation under the relationship of C>A>B. The inert gas cannot flow into the compression chamber 2, and a central part of the compression chamber 2 is communicated with a discharge hole 12 in the operation under the relationship of A>B≈C, when A is the pressure of the inert gas to be introduced into the compression chamber 2, B is the pressure in the compression chamber 2, and C is the pressure in the discharge hole 12 communicated with the compression chamber 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixed scroll in which a spiral fixed wrap is provided on the surface of a fixed end plate forming a compression chamber in a housing, and a spiral orbit wrap provided on the surface of the orbiting end plate. The orbiting scroll and the orbiting scroll are fitted to each other by being shifted from each other by 180 °, and the orbiting scroll is rotated with respect to the fixed scroll by the drive shaft. The present invention relates to a scroll-type vacuum pump that suppresses pressure.

[0002]

2. Description of the Related Art In a scroll-type vacuum pump as described in the preceding paragraph, when a halogen-based gas or an active gas is evacuated, for example, undesired reaction products are produced on the surface or wrap of the end plates of both the orbiting and fixed scrolls. May adhere to the side surfaces and their end plates and may be left behind, or may be discharged into the atmosphere from a discharge port to adversely affect the environment.

In order to suppress the generation of such reaction products and to reduce deterioration and wear of various elements in the vacuum pump, inert gas such as nitrogen gas is introduced into the compression chamber of the housing with driving of the orbiting scroll. The introduction of gas is described in, for example, JP-A-1-216082 and JP-B-7-58077.

Further, Japanese Patent Application Laid-Open No.
Japanese Patent No. 32767 discloses a method of drying heated air or nitrogen gas as a gas for gas ballast in order to remove moisture accumulated inside the compression chamber of a scroll type vacuum pump or dilute toxic gas. It is described to introduce a gas or a diluting gas (these are collectively referred to as an inert gas).

[0005] In the scroll type vacuum pumps described in the above publications, the inside of the compression chamber is communicated with an inert gas source.

[0006] When the vacuum pump as described above starts suction in the sealed container in which the inside is in the atmospheric pressure state, for a short time after the start, the vacuum pump operates in the same pressurizing action as the compressor. Then, after the suction pressure in the compression chamber in which the suction volume is formed becomes lower than the atmospheric pressure, the normal function of the vacuum pump is achieved for the first time.

[0007] Therefore, the inert gas is sucked into the compression chamber, and the harmful gas contained in the sealed container is eliminated, undesired reaction products are generated, or the internal mechanism of the vacuum pump is deteriorated or worn. Is prevented or reduced.

However, when the vacuum pump is stopped, the inert gas which has been sucked into the compression chamber is sucked in the direction of the suction port and flows into the closed container connected thereto.
The degree of vacuum is reduced.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a vacuum pump in which an inert gas is automatically sucked into a compression chamber during operation as described above. It is an object of the present invention to provide a scroll type vacuum pump in which gas is never sucked in the direction of a suction port.

[0010]

According to the present invention, the above-mentioned problem is solved as follows. (1) a spiral fixed wrap provided on the fixed scroll;
A scroll-type vacuum pump in which a spiral orbital wrap provided in an orbiting scroll is fitted into each other in a compression chamber provided in a housing and the orbiting scroll is rotated with respect to a fixed scroll without rotating. An inlet for connecting the inert gas supply source and the vicinity of the center of the compression chamber is provided, and the inside of the introduction hole is opened and closed according to the following pressure relationship to thereby supply the inert gas supply source and the compression chamber. A check valve is provided for communicating and shutting off. A is the pressure of the inert gas introduced into the compression chamber, B is the pressure in the compression chamber, C is the pressure in the discharge port connected to the compression chamber, and C>A> B
During operation, inert gas can flow into the compression chamber,
There is no backflow. At the time of the stop where A> B ≒ C, the inert gas cannot flow into the compression chamber, and the center of the compression chamber communicates with the discharge hole.

(2) In the above item (1), the check valve can be moved in the axial direction of the valve shaft inserted into the center shaft hole of the cylindrical body having the conical contact surfaces recessed at both ends. Accompanying this, one is in contact with the contact surface, and the other is fixed with a valve plate so as to be separated from the contact surface, the pressure of the inert gas introduced into the introduction hole, and the pressure in the compression chamber. The valve element is adapted to move in accordance with a change in the pressure and the pressure of the discharge gas discharged from the compression chamber, and the inert gas according to claim 1 can be introduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is also directed to a scroll type vacuum pump having a single-sided orbiting scroll in which a revolving wrap is provided only on one side of a head plate. The present invention is equally applicable to a scroll type vacuum pump provided with a scroll. Hereinafter, an example in which the present invention is applied to a double-sided type will be described with reference to the drawings.

In the drawing, (1) is a housing having a closed disk-shaped compression chamber (2), and a housing (3) and a lid (4).
It consists of

The housing (3) and the lid (4) have fixed end plates (3a) and (4a) located opposite to both sides of the compression chamber (2). The fixed scrolls (3c) (4c)
c) is formed.

In the middle of the opposed fixed end plates (3a) and (4a), the orbiting scroll (5) is provided in the compression chamber (2).
It is provided so as to be able to turn around the axis of (2).

The orbiting scroll (5) is provided with upright orbiting wraps (5b) and (5b) fitted on and engaged with the fixed scroll (3c) at 180 ° on both sides of the orbiting side end plate (5a).
A bearing (9) is attached to an eccentric shaft (8a) of a drive shaft (8) fitted into the center of the housing (1) via bearings (6) and (7).
Is pivoted through.

Further, the orbiting scroll (5) is locked to the housing (1) via three auxiliary crankshaft mechanisms (not shown) arranged on the same circumference at equal intervals from each other. When the drive shaft (8) rotates, the orbiting scroll
(5) makes an eccentric orbiting motion in the compression chamber (2), so that the radial dimension of the space between the fixed wrap (4b) and the revolving wrap (5b) meshing with each other changes.

Thus, the gas in the closed vessel (11) connected to the suction port (10) provided on the outer peripheral portion of the housing (1) is sucked, and the discharge port provided near the center of the housing (1). (12)
By discharging more, the inside of the closed container is decompressed to a desired degree of vacuum.

The above is a description of only a typical configuration of a scroll type vacuum pump to which the present invention is applied. This configuration itself is well known to those skilled in the art and is directly related to the present invention. I don't think there is any need for further explanation.

In the present invention, the housing (1) includes:
An introduction hole (13) is formed separately from the suction hole (10), and a check valve (14) is provided therein.

In the illustrated embodiment, the introduction hole (13) is formed in the housing (1) in the radial direction from the vicinity of the center of the housing (4), and its outer end is open. In the opening,
An unillustrated inert gas source is connected.

The check valve (14) comprises a valve seat (15) and a valve element (16), and is inserted near the inner end of the introduction hole (13).

As shown in the figure, the valve seat (15) has a cylindrical body (1) in which a small-diameter shaft hole (17) facing the axial direction is formed at the center.
8) Conical contact surfaces facing inward in the axial direction on both upper and lower end surfaces
(19) This is formed with (19), and a through hole (20) facing in the radial direction is formed in the central part in the axial direction.

On the other hand, a communication hole (21) communicating with the inside of the compression chamber (2) is formed at the inner end (upper end in the figure) of the introduction hole (13), and the valve seat (15) is The insertion hole (20) is inserted near the inner end of the introduction hole (13) so as to match the communication hole (21), and is hermetically fixed via a seal (22).

The valve body (16) is formed by fixing upper and lower two circular valve plates (24) and (24) to a valve shaft (23) at intervals, and the upper and lower ends of the valve shaft (23) are The upper and lower valve plates are slidably fitted to the upper and lower air-permeable bearing pieces (25, 25) fixed in the introduction hole (13).
When one of (24) contacts the conical contact surface (19) of the valve seat (15), the other is separated from the corresponding contact surface (19).

The valve plate (24) below the valve body (16) and the lower bearing piece
A compression spring (26) is fitted to the valve shaft (23) in a slightly compressed state, and the valve body (16) is always upward, that is, in the direction of the center of the compression chamber (2). Has been energized.

In the vicinity of the center of the end plate (4a) of the fixed scroll (4c), a guide hole (4d) extending in the axial direction is formed. In the vicinity of the center of the cover plate (4), an axial direction
d), a connection hole (4e) continuous with an inner end of the discharge hole (12) and the introduction hole (13) is formed.

The connection hole (4e) and the discharge hole (12) are connected via a valve (27) having a check function. The valve (27) is connected to the connection hole (4e) and the discharge hole (1
2), and at the same stop, the connection hole (4e) and the discharge hole (12)
This is to cut off the communication of

In the scroll type vacuum pump constructed as described above, the orbiting scroll (5) has the drive shaft (8).
When the is rotated, the gas in the closed container (11) is
, And is sucked into the compression chamber (2), compressed by the orbiting movement of the orbiting scroll (5), and the end plate (4a) of the fixed roll (4c).
Axial hole (4d), connection hole (4
e) and is discharged through radial discharge holes (12) formed in the cover plate (4).

By the way, since the inside of the sealed container (11) to be sucked is under atmospheric pressure, when the orbiting scroll (5) is started, for a certain period of time, this scroll type vacuum pump operates in the same manner as the compressor. I do.

When the pressure in the closed vessel (11) becomes lower than the atmospheric pressure, the vacuum pump operates to exhibit its original function, and the pressure in the compression chamber (2) is gradually reduced.

When the pressure (A) of the inert gas connected to the inlet (13) is equal to the atmospheric pressure, the pressure (B) in the compression chamber (2) becomes negative with the operation of the scroll vacuum pump. The pressure (C) in the guide hole (4d), the connection hole (4e), and the discharge hole (12) becomes higher than the atmospheric pressure.

That is, the pressure relationship between the above-mentioned parts during operation is as follows. C>A> B

Accordingly, during operation, the valve element (16) is lowered as shown in FIG. 2, and the lower valve plate (24) moves away from the corresponding conical abutment surface (19), Upper valve body (24)
Abuts against the corresponding conical abutment surface (19). Therefore, the inert gas connected to the introduction hole (13) passes through the through-hole (20) of the check valve (14).
Through the communication hole (21) and into the compression chamber (2).
(2) Cooling and water removal, harmful gas dilution, reaction product adhesion prevention, etc. are achieved, and deterioration and wear of each bearing and seal are reduced.

When the operation is stopped, the pressure (A) of the inert gas in the introduction hole (13) is reduced by the pressure (B) in the compression chamber (2), the connection hole (4e) and the discharge hole (12). Pressure (C) (pressure B
The same as, or almost equal to). That is, A> B ≒ C.

Accordingly, as shown in FIG. 1, the valve element (16) is raised, and the lower valve plate (24) comes into contact with the corresponding conical abutment surface (19) and the upper valve plate (19). 24) is apart from the corresponding conical abutment surface (19), and the pressure (B) in the compression chamber and the pressure (C) in the discharge port connected to the compression chamber are changed by the communication hole (21) and the communication hole (20). ),
It communicates via the shaft hole (17).

The compression spring (26) is not necessarily constructed because the valve plate (24) of the check valve (14) comes into contact with and separates from the conical abutment surface (19) in a pressure relationship. Although not essential, it helps to ensure that the lower valve plate (24) abuts against the abutment surface (19).

Therefore, even though the pressure in the compression chamber (2) and the connection hole (4e) is reduced, the inert gas is sucked into the compression chamber (2) to reduce the degree of vacuum. Never.

The introduction hole (13) is provided in the housing (3) of the housing (1).
An example in which an inert gas source is connected to the opening at the outer end of the housing (1) is described. ) May be drilled in the axial direction from near the center of the housing (3), and its outer end may be open, and an inert gas source may be connected to this opening.

Further, the valve plate (24) arranged on the upper side shown in FIG. 3 communicates with the connection hole (4e), the valve plate (24) arranged on the lower side communicates with the inert gas source, and further communicates with the through hole (20). By connecting to the hole (21) respectively, the above-mentioned effect can be obtained by mounting the check valve itself outside the housing (1) without providing the check valve inside the housing (1). Included in the invention.

The inert gas handled in the present invention includes a dry gas such as air and nitrogen gas, and a diluting gas.

[0042]

According to the present invention, the inert gas is automatically sucked into the compression chamber during the operation by the check valve which moves the valve body in three pressure relations, and accumulates in the compression chamber when the operation is stopped. The inert gas does not flow into the suctioned closed container and does not increase the pressure to cause vacuum breakage.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view of a main part showing a state when operation is stopped according to an embodiment of the present invention.

FIG. 2 is a vertical sectional front view during operation.

FIG. 3 is an enlarged vertical sectional front view showing a check valve inserted into an introduction hole.

[Explanation of symbols]

 (1) Housing (2) Compression chamber (3) Housing (3a) Fixed side end plate (3b) Fixed wrap (3c) Fixed scroll (4) Lid (4a) Fixed side end plate (4b) Fixed wrap (4c) Fixed Scroll (4d) Guide hole (4e) Connection hole (5) Orbiting scroll (5a) Orbiting end plate (5b) Orbiting wrap (6) (7) Bearing (8) Drive shaft (8a) Eccentric shaft (9) Bearing ( 10) Suction hole (11) Sealed container (12) Discharge hole (13) Inlet hole (14) Check valve (15) Valve seat (16) Valve (17) Shaft hole (18) Cylindrical body (19) Conical Contact surface (20) Through hole (21) Communication hole (22) Seal (23) Valve shaft (24) Valve plate (25) Bearing piece (26) Compression spring (27) Valve (A) Introduced inert gas (B) Pressure in compression chamber (C) Pressure in discharge hole connected to compression chamber

Claims (2)

[Claims] A spiral fixed wrap provided on a fixed scroll and a spiral fixed wrap provided on a revolving scroll are fitted into each other in a compression chamber provided on a housing, and the revolving scroll does not rotate. In a scroll type vacuum pump adapted to be swiveled with respect to a fixed scroll, a housing is provided with an introduction hole for connecting a supply source of an inert gas and a vicinity of a center portion of a compression chamber,
In addition, an inert gas can be introduced into the introduction hole, which is provided with a check valve that opens and closes in the following pressure relationship to communicate and shut off the supply source of the inert gas and the compression chamber. Scroll type vacuum pump. A is the pressure of the inert gas introduced into the compression chamber, B is the pressure in the compression chamber, C is the pressure in the discharge port connected to the compression chamber, and during the operation where C>A> B, the inert gas is compressed. It can flow into the room, but not backflow. At the time of the stop where A> B ≒ C, the inert gas cannot flow into the compression chamber, and the center of the compression chamber communicates with the discharge hole. 2. A check valve is inserted into a central shaft hole of a cylindrical body having a conical abutment surface recessed at both ends thereof, and one of the check valves is brought into contact with the valve shaft in the axial direction thereof. Abut the surface, the other is fixed to the valve plate so as to be separated from the contact surface, the pressure of the inert gas introduced into the introduction hole,
2. The scroll type in which an inert gas can be introduced according to claim 1, wherein the valve element moves in accordance with a change in the pressure in the compression chamber and the pressure of the gas discharged from the compression chamber. Vacuum pump.