JPH0244076Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention relates to a two-stage water ring vacuum pump. two impellers having
This invention relates to an improvement of a two-stage water ring type vacuum pump for high vacuum having two blades of each impeller and a side plate that cooperates with each other to form a chamber.

[Conventional technology]

Conventional vacuum pumps of this type include those in which both stage sides are formed in a port plate type, and those in which both stage sides are formed in a port cylinder type.
In this case, the former port plate type, as shown in FIG.
A type in which a suction port d and a discharge port e are provided in the body c, and a liquid such as water sealed in the body a, that is, seal water, performs a piston action, and gas is pumped through the suction port d and the discharge port e. The latter, that is, the port cylinder type, although not shown, forms a suction port and a discharge port that are in contact with the inner surface of the impeller, and similarly to the above, the suction port is opened by making the sealed water perform a piston action. This is a type in which gas is pumped in the axial direction of the impeller through a discharge port and a discharge port.

This type of vacuum pump configured as above is
The specifications of each part are determined by the compression conditions, and the opening area and shape of the discharge port are particularly important requirements. Especially for two-stage water ring vacuum pumps, the conditions to be compressed by each stage are always Critical. Furthermore, since this type of vacuum pump is used at a high pressure ratio, that is, in a high vacuum state, it is necessary to supply a large amount of sealing water to prevent the vacuum from breaking, compared to when it is used at a low pressure ratio. Therefore, in response to this, it is necessary to discharge sealed water from the discharge port along with the compressed gas on the discharge side of the vacuum pump. In addition, the water seal must withstand use under various conditions such as being subjected to high-speed rotational force by an impeller and being subjected to large centrifugal force within the pump.

In the port plate type, in order to discharge a large amount of sealed water together with the compressed gas under the above conditions, the position of the discharge port e must be adjusted so that the rotational flow of the sealed water is controlled as shown in Figure 3. is completely different from the direction f, and must be discharged in a direction perpendicular to the flow, which does not result in ideal discharge. For this reason, there is a possibility that there will be a part where the flow velocity is extremely high at the corner of the discharge port e, and there is a risk that the first-stage impeller b, which is under a particularly high vacuum, may cause local cavitation and be corroded. . Furthermore, such cavitation makes it impossible to operate the vacuum pump stably and may even cause a failure.
In addition, from a manufacturing standpoint, especially in an integrated structure in which impellers b and b' are mounted coaxially, the positions A, B, and C shown in Fig. 2 require accurate positioning of the end faces.
and D, and both the fixed part and the rotating part require high axial accuracy. That is, impeller b,
Since the size of the gap between b' and the side plates c and c greatly affects the performance of the vacuum pump, it is required to ensure a highly accurate gap at the four locations.

On the other hand, the port cylinder type has a plurality of structures compared to the port plate type.
In addition, in the case of an integrated structure, it is necessary to maintain an accurate gap in the diametrical direction of the inner surface of both impellers, which requires precise centering. In addition, the pump itself is somewhat large, so it has drawbacks such as being cumbersome and expensive to manufacture. However, on the other hand, since the absolute flow of air is simple, it has the excellent feature that cavitation does not easily occur even when operating at a vacuum level near the saturated vapor pressure of water.

[The problem that the idea attempts to solve]

This idea was made in view of the above circumstances,
In addition to preventing cavitation during operation,
The purpose of this invention is to improve the performance of the pump, and to facilitate and inexpensively manufacture the pump.

[Means to solve the problem]

That is, this invention includes two impellers each having a plurality of blades rotatably arranged within a cylindrical body;
In a two-stage water ring vacuum pump, which has a side plate that cooperates with two blades of each impeller to form a chamber, and in which both stages of impellers are arranged on the same axis. , the first stage side is formed in a port cylinder type for pumping gas in the axial direction of the impeller through a suction port and discharge port in contact with the inner surface of the impeller, and the second stage side is formed on the side surface of the impeller. This invention proposes a two-stage water ring vacuum pump characterized by being formed in a port plate type that pumps gas to the side of an impeller through a suction port and a discharge port that are in contact with each other.

[Effect]

In this invention with the above-mentioned structure, cavitation is prevented particularly on the first stage side where the vacuum is high, pump performance is improved, and it is possible to manufacture the pump easily and inexpensively.

〔Example〕

Embodiments of this invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a cross-sectional view of the vacuum pump of this invention. In the figure, 1, 1 is a cylindrical body, for example, formed in a cylindrical shape, and a wall plate 2 held between them. Therefore, the first stage side space 3 and the second stage side space 4
It is divided into. Reference numeral 5 denotes a rotation shaft passing through an eccentric position of the body 1, and is rotatably supported by bearings 6, 6 disposed at the ends of the body 1, and a drive motor (not shown) is connected to one end of the rotation shaft. connected. and the first stage and second stage side spaces 3,
4, a key 7 is provided at one end of the rotating shaft 5, and a plurality of blades 8a, 8a are installed in the radial direction, respectively.
... or 9a, 9a... is attached to the impeller 8 or 9. In this case, a port cylinder 12 having a suction port 10 and a discharge port 11 is in contact with the inner surface of the impeller 8 in the first stage side space 3, and one side of the first stage side space 3 is provided with a suction port 10 and a suction port 12. a communication port 14 that communicates with the passage 13;
A communication port 16 is provided that communicates the discharge port 11 and the discharge passage 15. Therefore, when the impeller 8 rotates with the rotation of the rotating shaft 5, the space 3
Sealed water (not shown) sealed inside each blade 8
A piston action is performed while forming a water film between a and 8a, and gas is forced into the axial direction of the impeller 8 through the suction and discharge ports 10 and 11 by this piston action.

On the other hand, the impeller 9 in the second stage side space 4 is in contact with the partition wall 2 on one side and the side plate 17 on the other side, and the impeller 9 is in contact with the partition wall 2 and the side wall 16 and the two blades 9a, 9a. The side plate 17 has a suction port 10' communicating with the suction passage 13' and a discharge port 11 communicating with the discharge passage 15'. ' is provided. Therefore, when the impeller 9 rotates along with the rotating shaft 5, gas is forced to the side of the impeller 9 through the suction and discharge ports 10' and 11'.

Note that the discharge passage 15 on the first stage side and the suction passage 13' on the second stage side are connected via a connecting pipe 18.

In the above embodiment, the case where the body 1 is cylindrical has been described, but it does not necessarily have to be cylindrical, and it goes without saying that similar effects can be obtained even if the body is oval, for example.

[Effect of idea]

As explained above, according to the two-stage water ring vacuum pump of this invention, in which both stages of impellers are formed on the same axis, the first stage side, which produces a high vacuum, is formed as a port cylinder type. In addition, since the second stage side is formed in a port plate type, cavitation can be prevented even on the first stage side, which is used near the saturated vapor pressure of water, and the inner surface of the impeller and the port cylinder can be prevented. The gap setting can be maintained with high precision to improve pump performance.
The second stage side, which does not have a high vacuum compared to the first stage side, uses a port plate type that is easy to manufacture, and has features such as maintaining high performance due to the gap between the impeller and the side plate. However, the synergistic effect between the two stages provides excellent effects such as high-performance pumping action, so its utility value is remarkable.

[Brief explanation of drawings]

Figure 1 is a sectional view showing the vacuum pump of this invention.
FIG. 2 is a sectional view showing a conventional port plate type vacuum pump, and FIG. 3 is a sectional view taken along the line - in FIG. In the figure, 1... fuselage, 3... 1st stage side space, 4...
2nd stage side space, 5...rotating shaft, 8a, 9a...blade,
8, 9... Impeller, 10, 10'... Suction port, 1
1, 11'...discharge port, 12...port cylinder,
17...Side plate.

Claims (1)

[Scope of utility model registration request] It has two impellers having a plurality of blades that are rotatably arranged in a cylindrical body, and a side plate that cooperates with the two blades of each impeller to form a chamber, and has both stages. In a two-stage water ring vacuum pump formed by arranging two impellers on the same axis, the first stage side is configured to supply gas to the impeller through a suction port and a discharge port that are in contact with the inner surface of the impeller. The second stage side is formed as a port cylinder type that pumps gas in the axial direction, and the second stage side is formed as a port plate type that pumps gas to the side of the impeller through a suction port and a discharge port that contact the side surface of the impeller. A two-stage water ring vacuum pump characterized by: