JP2018138778A - Liquid ring vacuum pump - Google Patents

Abstract

[Problem] To provide a liquid ring vacuum pump that can share a casing for multiple models with different pumping speeds and outputs, without having to design an impeller and casing specifically for each pumping speed or output. [Solution] In a liquid ring vacuum pump comprising a casing (2) that contains a sealing liquid and at least one impeller (3) housed within the casing (2), the casing (2) is formed with a predetermined inner diameter (D1), and an annular member (4) is provided between the inner peripheral surface of the casing (2) and the outer peripheral surface of the impeller (3), the annular member (4) having an outer diameter (D3) that is approximately the same as the predetermined inner diameter (D1) of the casing (2) and that matches the outer diameter (D2) of the impeller (3). [Selected Figure] Figure 2

Description

  The present invention provides a liquid seal type comprising a circular casing, an impeller mounted eccentrically with respect to the center of the circular casing, and an annular member installed between the inner peripheral surface of the casing and the outer peripheral surface of the impeller. It relates to a vacuum pump.

  A circular casing and an impeller mounted eccentrically with respect to the center of the circular casing, enclosing water or other liquid in the casing, and forming a liquid film along the inner wall of the casing by centrifugal force due to rotation of the impeller; There is known a liquid ring vacuum pump that performs a pumping action by utilizing a volume change of a blade chamber formed by a liquid film and two adjacent blades. The liquid ring vacuum pump is driven by being connected to the main shaft of a separate electric motor or is driven by attaching the impeller to the main shaft of a direct acting motor.

In the liquid ring type vacuum pump, in order to form a blade chamber, it is necessary that the blade tip on the outer periphery of the impeller is always immersed in the seal solution. On the side surface of the impeller and the inner wall surface of the casing, a liquid film must be formed by forming a small gap to form a blade chamber. Therefore, the impeller and the casing correspond one-to-one, and if the outer diameter of the impeller is determined, the inner diameter of the casing is determined, and the impeller diameter and the casing inner diameter are in a dimensional relationship depending on each other.
In addition, since the liquid ring vacuum pump cannot exhibit stable performance unless it is operated at an appropriate peripheral speed, there is a limit to performance adjustment by changing the rotation speed. Therefore, in the conventional liquid ring vacuum pump, the impeller and the casing must be designed as a pair for each exhaust speed and output.

Utility Model Registration No. 2508668

As described above, the conventional liquid ring vacuum pump has a problem that the impeller and the casing must be designed as a pair for each exhaust speed and output.
The present invention has been made in view of the above circumstances, and does not design an impeller and a casing for each exhaust speed and output, and can share the casing in a plurality of models having different exhaust speeds and outputs. An object of the present invention is to provide a liquid ring vacuum pump capable of performing

  In order to achieve the above-described object, a liquid ring vacuum pump according to the present invention is a liquid ring vacuum pump including a casing that stores a liquid seal and at least one impeller that is housed in the casing. The casing is formed with a predetermined inner diameter, and has an outer diameter that is substantially the same as the predetermined inner diameter of the casing between the inner peripheral surface of the casing and the outer peripheral surface of the impeller, and is outside the impeller. An annular member having an inner diameter adapted to the diameter is provided.

In a preferred aspect of the present invention, the axial dimension of the impeller housing portion of the casing and the axial dimension of the annular member are substantially the same.
In a preferred aspect of the present invention, the annular member is fixed to the casing on at least a part of an outer periphery or an end surface.
In a preferred aspect of the present invention, the space formed by the inner diameter of the annular member is a cylinder parallel to the main shaft that supports the impeller.
In a preferred aspect of the present invention, the inner and outer diameter axes of the annular member are eccentric.

  According to the present invention, by inserting an annular member inside the casing, the casing inner diameter can be reduced, and the casing can be shared by a plurality of models having different exhaust speeds and outputs. And the number of models which can share a casing can be increased by adjusting the radial direction thickness of an annular member suitably.

FIG. 1 is a schematic cross-sectional view showing an embodiment of a liquid ring vacuum pump according to the present invention. FIG. 2 is a diagram showing details of the pump chamber and the impeller disposed in the pump chamber, and is a cross-sectional view taken along the line II-II in FIG. 1. FIG. 3 is a schematic cross-sectional view showing another embodiment of a liquid ring vacuum pump according to the present invention. 4A to 4G are schematic cross-sectional views showing various cross-sectional shapes of the annular member arranged in the casing. 5A and 5B are side views of an annular member having a groove.

Hereinafter, an embodiment of a liquid ring vacuum pump according to the present invention will be described with reference to FIGS. 1 to 5, the same or corresponding components are denoted by the same reference numerals, and redundant description is omitted.
FIG. 1 is a schematic cross-sectional view showing an embodiment of a liquid ring vacuum pump according to the present invention. As shown in FIG. 1, the liquid ring vacuum pump includes a casing 2 that forms a pump chamber 1 therein. An impeller 3 is provided in the pump chamber 1. An annular member 4 is provided between the inner peripheral surface of the casing 2 and the outer peripheral surface of the impeller 3. The axial dimension of the impeller housing portion of the casing 2 and the axial dimension of the annular member 4 are set to be substantially the same. The annular member 4 is fixed to the casing 2 at least at a part of the outer periphery or end face. The impeller 3 is fixed to a main shaft (rotary shaft) 7 of the motor 6.

  The opening on the front end side of the casing 2 is closed by an intake side cover 8 and forms a pump chamber 1 as a space sealed by the intake side cover 8. An exhaust casing 9 is connected to the rear end side of the casing 2. An intake port 8 s is formed in the intake side cover 8, and gas (for example, air) is sucked into the pump chamber 1 from the intake port 8 s. An exhaust port Pd is formed in the casing 2 and the exhaust casing 9. An exhaust port 9d is formed in the exhaust casing 9, and the gas discharged from the pump chamber 1 through the exhaust port Pd is discharged from the exhaust port 9d of the exhaust casing 9 to the outside. A shaft seal component 10 such as a mechanical seal for shaft sealing is attached to a portion where the main shaft 7 passes through the exhaust casing 9. The opening of the exhaust casing 9 is closed by a motor flange 12.

  As shown in FIG. 1, the impeller 3 is attached to the shaft end portion of the main shaft 7 of the motor 6. The main shaft 7 that supports the impeller 3 is supported in a cantilever structure (overhang structure) by a bearing 14 provided in a motor casing 13 of the motor 6.

  FIG. 2 is a diagram showing details of the casing 2, the impeller 3 and the annular member 4 arranged in the casing 2, and is a cross-sectional view taken along line II-II in FIG. 1. As shown in FIG. 2, the casing 2 has a circular internal space. An impeller 3 is fixed to the main shaft 7, and the impeller 3 is eccentric with respect to the circular inner space of the casing 2. An annular member 4 having a rectangular cross section is disposed between the inner peripheral surface of the casing 2 and the outer peripheral surface of the impeller 3. The annular member 4 has a circular internal space inside, and this internal space is the pump chamber 1. The impeller 3 includes a cylindrical boss portion 41 and a plurality of blades 42 extending radially from the boss portion 41 at equal intervals.

  As shown in FIG. 2, the casing 2 is formed with a predetermined inner diameter D1. The annular member 4 has an outer diameter substantially the same as the predetermined inner diameter D1 of the casing 2 and an inner diameter D3 that matches the outer diameter D2 of the impeller 3. That is, the inner diameter D3 of the annular member 4 is an inner diameter determined by the outer diameter D2 of the impeller 3. In FIG. 2, of the three vertical one-dot chain lines, the right one-dot chain line L 1 is a line representing the center of the casing 2, and the center one-dot chain line L 2 is a line representing the inner diameter center of the annular member 4. A one-dot chain line L3 is a line representing the center of the impeller 3. As described above, the center of the impeller 3 is eccentric with respect to the center of the annular member 4 by making the inner diameter of the annular member 4 eccentric with respect to the outer diameter of the annular member 4 (that is, the inner diameter of the casing 2). The amount can be adjusted.

  According to the liquid ring vacuum pump of the present invention shown in FIGS. 1 and 2, the casing 2 and the impeller 3 are designed as a pair with a model having a large exhaust speed and output, and a model with a smaller exhaust speed and output than that is designed. In this case, the impeller diameter is reduced, but the casing 2 is not changed as it is, and the annular member 4 is inserted inside the casing 2 so that the inner peripheral surface of the annular member 4 functions as the inner peripheral surface of the casing. That is, by inserting the annular member 4 inside the casing 2, the casing inner diameter can be reduced, and the casing 2 can be shared by a plurality of models having different exhaust speeds and outputs. And the number of models which can share the casing 2 can be increased by adjusting the radial direction thickness of the annular member 4 suitably.

  In FIG. 2, the impeller 3 rotates counterclockwise. The internal space of the annular member 4 is supplied with an amount of liquid (for example, water) that fills about half of the volume. When the impeller 3 rotates, the plurality of blades 42 scrape liquid out in the outer circumferential direction of the impeller 3, and the liquid circulates along the inner surface of the annular member 4 by centrifugal force, and the annular liquid film (liquid ring) LF Form. In the pump chamber 1, the gas is compressed by using the volume change of each blade chamber Rb formed by the both side walls of the casing and the two blades 42 adjacent to the liquid film LF to perform a pump action.

  FIG. 3 is a schematic cross-sectional view showing another embodiment of a liquid ring vacuum pump according to the present invention. In FIG. 3, a two-stage liquid ring vacuum pump is illustrated as a liquid ring vacuum pump. As shown in FIG. 3, the two-stage liquid ring vacuum pump has a first casing 2-1 that forms a first-stage pump chamber 1-1 and a second-stage pump chamber 1-2 inside. And a second casing 2-2. The first stage pump chamber 1-1 is provided with a first stage impeller 3-1 on the intake side, and the second stage impeller 3-2 is provided on the second stage pump chamber 1-2. Yes. A first annular member 4-1 is provided between the inner peripheral surface of the first casing 2-1 and the outer peripheral surface of the first stage impeller 3-1. A second annular member 4-2 is provided between the inner peripheral surface of the second casing 2-2 and the outer peripheral surface of the second stage impeller 3-2. The first stage impeller 3-1 and the second stage impeller 3-2 are fixed to the same main shaft (rotary shaft) 7 of the motor 6. A side wall 2p extending inward in the radial direction is formed in the first casing 2-1, and the first stage pump chamber 1-1 and the second stage pump chamber 1-2 are partitioned by the side wall 2p. An exhaust port Pd of the first stage pump chamber 1-1 and an intake port Ps of the second stage pump chamber 1-2 are formed on the side wall 2p, and the first stage pump is formed by the exhaust port Pd and the intake port Ps. The chamber 1-1 communicates with the second-stage pump chamber 1-2.

  The opening on the front end side of the first casing 2-1 is closed by an intake side cover 8, and a first stage pump chamber 1-1 is formed as a space sealed by the intake side cover 8. An exhaust casing 9 is connected to the rear end side of the second casing 2-2. An intake port 8s is formed in the intake side cover 8, and gas (for example, air) is sucked into the first stage pump chamber 1-1 from the intake port 8s. The second casing 2-2 and the exhaust casing 9 are formed with an exhaust port Pd of the second stage pump chamber 1-2. An exhaust port 9d is formed in the exhaust casing 9, and the gas discharged from the second-stage pump chamber 1-2 through the exhaust port Pd is discharged from the exhaust port 9d of the exhaust casing 9 to the outside. It has become. A shaft seal component 10 such as a mechanical seal for shaft sealing is attached to a portion where the main shaft 7 passes through the exhaust casing 9. The opening of the exhaust casing 9 is closed by a motor flange 12.

  As shown in FIG. 3, the first stage impeller 3-1 and the second stage impeller 3-2 are attached to the shaft end portion of the main shaft 7 of the motor 6. The main shaft 7 supporting the first stage impeller 3-1 and the second stage impeller 3-2 is supported by a cantilever structure (overhang structure) by a bearing 14 provided on the motor casing 13 of the motor 6. Yes.

The cross-sectional structures of the first casing 2-1, the first stage impeller 3-1 and the first annular member 4-1, which are arranged in the first casing 2-1, shown in FIG. The dimensional relationship among the first casing 2-1, the first stage impeller 3-1, and the first annular member 4-1 is the same as that in FIG.
Moreover, the second casing 2-2 shown in FIG. 3, the second stage impeller 3-2 arranged in the second casing 2-2, and the cross-sectional structure of the second annular member 4-2 are the same as those in FIG. 2. In addition, the dimensional relationship among the second casing 2-2, the second stage impeller 3-2, and the second annular member 4-2 is the same as that in FIG.

  According to the two-stage liquid ring vacuum pump of the present invention shown in FIG. 3, the first annular member 4-1 is placed inside the first casing 2-1, and the second annular member inside the second casing 2-2. By inserting 4-2, the inner peripheral surface of the first annular member 4-1 and the inner peripheral surface of the second annular member 4-2 are caused to function as the inner peripheral surface of the casing, respectively. That is, by placing the first annular member 4-1 and the second annular member 4-2 inside the first casing 2-1 and the second casing 2-2, the casing inner diameter can be reduced, and the exhaust speed is reduced. The first casing 2-1 and the second casing 2-2 can be shared by a plurality of different models.

Next, the material of each member used in the liquid ring vacuum pump shown in FIGS. 1 to 3 will be described.
The material of the casing 2, the first casing 2-1 and the second casing 2-2 may be a metal such as stainless steel, cast iron casting, copper alloy casting, stainless casting. The material of the impeller 3, first stage impeller 3-1 and second stage impeller 3-2 may be stainless steel, cast iron casting, copper alloy casting, stainless casting, or the like.
Metals such as FC, SUS304, and SCS13 may be used as the material of the annular member 4, the first annular member 4-1, and the second annular member 4-2. Resin such as PP, PE, PPO, PVC, PPS, ABS, PA66 may be used as the material of the annular member 4, the first annular member 4-1, and the second annular member 4-2. Since the specific gravity of the resin is lighter than that of metals, the weight can be reduced.
As the material of the annular member 4, the first annular member 4-1, and the second annular member 4-2, rubber materials such as NR, NBR, EPDM, CR, and FKM may be used. Since the specific gravity of the rubber material is lighter than that of metals, the weight can be reduced. In addition, when exhaust noise becomes a problem during operation, noise reduction can be realized by using a rubber material for the annular member 4, the first annular member 4-1, and the second annular member 4-2.
If the casing and the annular member are made of different materials, the annular member 4, the first annular member 4-1 and the second annular member 4-2 may be press-fitted and fixed using a difference in linear expansion coefficient. Attachment of the annular member 4, the first annular member 4-1, and the second annular member 4-2 may be fixed by a fastener member such as a bolt.

4A to 4G are schematic cross-sectional views showing various cross-sectional shapes of the annular member 4 disposed in the casing 2.
In the embodiment shown in FIGS. 1 and 2, the annular member 4 has a cylindrical shape as a whole, and the sectional shape of the annular member 4 is a rectangular cross section having no groove. On the other hand, in the example shown in FIGS. 4A to 4G, the annular member 4 has the same cylindrical shape as the whole, but the sectional shape of the annular member 4 has various grooves g. Cross-sectional shape. Specifically, the cross-sectional shape of the annular member 4 includes an E-shaped cross section (FIG. 4A), an inverted U-shaped cross section (FIG. 4B), a U-shaped cross section (FIG. 4C), U-shaped cross section (FIG. 4 (d)), inverted T-shaped cross section (FIG. 4 (e)), inverted L-shaped cross section (FIG. 4 (f)), L-shaped cross section (FIG. 4 (g)) is there. As shown in FIGS. 4A to 4G, the inner circumferential surface of the annular member 4 is a circumferential surface, and the liquid circulates along the inner circumferential surface of the annular member 4, and the annular liquid film LF. As long as the cross-sectional shape of the annular member 4 can be formed, various cross-sectional shapes are allowed.

  5A and 5B are side views of the annular member 4 having a groove. Fig.5 (a) shows the example by which the groove | channel g is formed in the perimeter of the side surface of the annular member 4, and the groove | channel g shown to Fig.5 (a) is a circular groove | channel. FIG. 5B shows an example in which a part of the groove g formed on the side surface of the annular member 4 is missing, and the groove g shown in FIG. 5B is a substantially C-shaped groove.

  Although the embodiment of the present invention has been described so far, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention may be implemented in various different forms within the scope of the technical idea.

DESCRIPTION OF SYMBOLS 1 Pump chamber 1-1 1st stage pump chamber 1-2 2nd stage pump chamber 2 Casing 2-1 1st casing 2-2 2nd casing 2p Side wall 3 Impeller 3-1 1st stage impeller 3-2 2nd 2-stage impeller 4 annular member 4-1 first annular member 4-2 second annular member 6 motor 7 main shaft 8 intake side cover 8s intake port 9 exhaust casing 9d exhaust port 10 shaft seal part 12 motor flange 13 motor casing 14 bearing D1 Inner diameter of casing D2 Outer diameter of impeller D3 Inner diameter of annular member LF Liquid film (liquid ring)
Pd Exhaust port Ps Intake port Rb Blade chamber

Claims (5)

In a liquid ring vacuum pump comprising a casing for storing a sealing liquid and at least one impeller stored in the casing,
Forming the casing with a predetermined inner diameter;
An annular member having an outer diameter substantially the same as a predetermined inner diameter of the casing and an inner diameter adapted to the outer diameter of the impeller is provided between the inner peripheral surface of the casing and the outer peripheral surface of the impeller. A liquid ring vacuum pump characterized by being provided.   2. The liquid ring vacuum pump according to claim 1, wherein an axial dimension of the impeller housing portion of the casing and an axial dimension of the annular member are substantially the same.   The liquid ring vacuum pump according to claim 1 or 2, wherein the annular member is fixed to the casing at least at a part of an outer periphery or an end face.   4. The liquid ring vacuum pump according to claim 1, wherein the space formed by the inner diameter of the annular member is a cylinder parallel to a main shaft that supports the impeller. 5.   The liquid ring vacuum pump according to any one of claims 1 to 4, wherein an axis of an inner and outer diameter of the annular member is eccentric.

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