JP2508668Y2 - Structure of pump chamber in two-stage water-sealed vacuum pump - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-stage water-sealed vacuum pump, and more particularly to a structure of a pump chamber adapted to the air flow ratio of the first-stage pump chamber and the second-stage pump chamber. It is a thing.

[0002]

2. Description of the Related Art As is well known, by rotating a liquid (for example, water) in a pump chamber by an impeller,
There is known a water-sealed vacuum pump that sucks and discharges gas (for example, air) as the liquid moves in the radial direction of the impeller, and pumps or removes the gas. Various two-stage water-sealed vacuum pumps have been proposed, which are connected with each other by connecting the exhaust port of the first-stage pump and the intake port of the second-stage pump to obtain a higher degree of vacuum than that of the one-stage vacuum pump. ing.

Conventionally, this type of two-stage water-sealed vacuum pump has been
As shown in FIG. 7, a first stage pump unit 101, a second stage pump unit 102 and a bearing unit 103 are provided, and the communication plate 1 is provided between the first stage pump unit 101 and the second stage pump unit 102.
04 is provided and a first-stage pump chamber 105 partitioned by the communication plate 104 is provided with a first-stage impeller 106, and a second-stage pump chamber 107 is provided with a second-stage impeller 108. 106, 108
Are fixed to the same rotating shaft . The exhaust port of the first-stage pump chamber 105 and the intake port of the second-stage pump chamber 107 communicate with each other via the communication plate 104. In this configuration, water is supplied to the two-stage water-sealed vacuum pump directly to the intake port or, as shown in FIG. 7, from the water supply port 109 via the side surface of the first-stage impeller 106. First-stage pump chamber 105 and second-stage pump chamber 1
It supplies each into 07.

By the way, the two-stage water-sealed vacuum port as described above is used.
In the pump, the inhaled air enters the first-stage pump chamber 105.
The second stage pump is compressed at
Since it flows into the chamber 107, it should be placed in the second-stage pump chamber 107.
The air flow rate is the air flow rate in the first-stage pump chamber 105.
It is necessary to set less depending on the degree of compression compared to
There is. Therefore, normally, both impellers 106 and 108 are
Only the width dimension of is changed to correspond to the change of the air flow rate.

As described above, it is easy for a large-sized water-sealed vacuum pump to deal with a change in the air flow rate by changing only the width dimensions of the first-stage impeller 106 and the second-stage impeller 108. In the case of a small two-stage water-sealed vacuum pump, there are also problems in processing and blade strength, so the second-stage impeller 108
It is not desirable to make the width dimension of the tape too small.

Therefore, in the conventional small-sized two-stage water-sealed vacuum pump, the width ratio of the first-stage impeller 106 and the second-stage impeller 108, that is, the ratio of the air flow rate is too large.
It was not possible to set it quickly. Therefore, the air volume is compressed by the first stage pump chamber 105 was reduced, the
When it enters the second-stage pump chamber 107, it expands. Therefore, if the suction vacuum is high , or if
When used in a high region, cavitation is likely to occur even in the second-stage pump chamber 107, causing problems such as erosion and noise in pump components.

[0007]

SUMMARY OF THE INVENTION In view of the above problems, the present invention is directed to a first small-sized two-stage water-sealed vacuum pump.
The ratio between the intake air flow rates of the second-stage pump chamber and the second-stage pump chamber is made proper to prevent cavitation from occurring in the second-stage pump chamber.

[0008]

The present invention has been made to solve the above-mentioned problems, and it is a first stage impeller provided in the first stage pump chamber and a second stage provided in the second stage pump chamber. A two-stage water-sealed vacuum pump in which the stage impeller is fixed to the same rotary shaft, and the exhaust port of the first stage pump chamber and the intake port of the second stage pump chamber communicate with each other, in the center of the first stage pump chamber. than eccentricity of the center of the first stage impeller, it is characterized by having a reduced amount of eccentricity between the center and the center of the second stage pump chamber and the second stage impeller.

[0009]

According to this invention, the amount of eccentricity between the center of the second stage pump chamber and the center of the second stage impeller is smaller than the amount of eccentricity between the center of the first stage pump chamber and the center of the first stage impeller. Then
Since the ratio of the air flow rates of the first-stage pump chamber and the second-stage pump chamber was set to an appropriate ratio, the air compressed in the first-stage pump chamber and reduced in volume enters the second-stage pump chamber. Will not expand rapidly. Therefore, cavitation does not occur inside the second-stage pump chamber.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A concrete embodiment of the present invention will be described below in detail with reference to the drawings. As shown in FIG. 1, the two-stage water-sealed vacuum pump A includes a first-stage pump unit B, a second-stage pump unit C, and a bearing unit D, and the first-stage pump unit B and the second-stage pump unit C. A communication plate 1 is interposed between the first stage pump portion B and the second stage pump portion C and is connected to the bearing portion D by bolts 13.

The first-stage pump section B sucks air from one side and exhausts it to the other side, and is composed of an intake-side casing 2, a communication plate 1 and a first-stage port plate 4 interposed therebetween. A first-stage pump chamber 3 is formed in a portion sandwiched between the communication plate 1 and the first-stage port plate 4, and a first-stage impeller 5 is rotatably provided in the first-stage pump chamber 3. It is provided. Similarly, the second-stage pump section C sucks air from one side and exhausts it to the other side, and is composed of a communication plate 1, an exhaust-side casing 6 and a second-stage port plate 7 interposed therebetween. A second-stage pump chamber 8 is formed in a portion sandwiched between the communication plate 1 and the second-stage port plate 7, and a second-stage impeller 9 is rotatably provided in the second-stage pump chamber 8. It is provided. Then, the first stage impeller 5 and the second stage impeller 9
Are arranged on the same rotary shaft 10 and are fixed to the rotary shaft 10 by a C-shaped retaining ring via a key and a spring.

The bearing portion D is provided with a bearing (not shown) for rotatably supporting the bearing housing 11 and the rotary shaft 10, and the first stage pump portion B and the second stage pump portion C.
A drive motor (not shown) is arranged on the opposite side of.

As shown in FIGS. 1 and 2, the communication plate 1 has a first-stage pump chamber 3 formed on one side surface, and the center P of the first-stage pump chamber 3 is located at the center P of the first-stage impeller 5.
Is eccentric with respect to the center O of the
At "t"). Further, an exhaust port 1a of the first-stage pump chamber 3 is formed on one side surface of the communication plate 1, and an intake port 1b of the second-stage pump chamber 8 is formed on the other side surface thereof. First stage pump chamber 3 and second stage pump chamber 8 through port 1b
And communicate with.

As shown in FIG. 1, the intake side casing 2 has a water supply port 2a formed in the center thereof, and an intake port 2b formed at the upper side so as to communicate with the intake flow passage 2c. Further, as shown in FIG. 1, the first-stage side port plate 4 has a hole 4a formed in the center thereof and an intake port 4b formed around the hole 4a. As shown in FIG. 1, the exhaust side casing 6 is formed with a hole 6a for accommodating the mechanical seal 12 in the center, an exhaust port 6b is provided above the exhaust port 6b, and an exhaust gas communicating with the exhaust port 6b is formed. Channel 6
c is formed around the hole 6a.

Now, in this invention, the communication plate 1
Second-stage pump chamber 8 sandwiched between the second-stage port plate 7 and
2 and 3, a predetermined eccentricity amount s (second eccentricity s (smaller than the eccentricity amount t that eccentricizes the center P of the first-stage pump chamber 3 with respect to the center O of the first-stage impeller 5). The amount of eccentricity between the center R of the stage pump chamber 8 and the center O of the second stage impeller 9) is set as the set value. It is desirable to set 8 times. Thus, the eccentricity amount s between the center R of the second-stage pump chamber 8 and the center O of the second-stage impeller 9 is set smaller than the value of the eccentricity amount t, and the width of the second-stage impeller 9 is set to the first value. By narrowing the width of the stage impeller 5 by about 70%, the volume of the second stage pump chamber 8 becomes about 0.3 to 0.4 times the volume of the first stage pump chamber 3, As a result, the air flow rate between the first-stage pump chamber 3 and the second-stage pump chamber 8 becomes approximately 3: 1. Therefore, since the inner diameter of the second-stage pump chamber 8 is smaller than the inner diameter of the first-stage pump chamber 3, the intake port 1b and the second-stage side port plate 7 of the second-stage pump chamber 8 are
The shape of the second-stage exhaust port 7a formed on the side surface of FIG.
As shown in FIG. 5, the respective shapes are smaller than the conventional shapes shown in FIG.

The first-stage impeller 5 and the second-stage impeller 9 are, as shown in FIGS. 1 and 4, a plurality of blades 5a, 5a, ...
., a, 9a, ... In addition,
As described above, the width of the first-stage pump chamber 3 and the first-stage impeller 5 is wider than that of the second-stage pump chamber 8 and the second-stage impeller 9, respectively.

Next, 2 in the above embodiment of the present invention
The operation and action of the water-sealed vacuum pump A will be described. When water is supplied from the water supply port 2a of the intake side casing 2 and the rotation shaft 10 is rotated by the drive motor (not shown) to rotate the first stage impeller 5 and the second stage impeller 9, the first stage pump chamber 3 The water that has flowed into the second-stage pump chamber 8 and the water that has flowed into the second-stage pump chamber 8, respectively.
Flow along the inner peripheral wall of each of them, and circulate in an annular shape. The centers O of the first-stage impeller 5 and the second-stage impeller 9 are eccentric with respect to the centers P and R of the first-stage pump chamber 3 and the second-stage pump chamber 8, respectively. 2 blades 5a (9
Spaces (not shown) are formed between a) and the boss (not shown) and the water surface, respectively, and the rotation of the impeller expands and contracts these spaces to suck and discharge air, respectively.

On the other hand, the flow of air will be described first.
In the stage pump section B, the intake port 2 of the intake side casing 2
Air from b passes through the intake passage 2c of the intake casing 2 and is sucked into the first-stage pump chamber 3 from the intake port 4b of the first-stage port plate 4. The air discharged from the first-stage pump chamber 3 is compressed in the first-stage pump chamber 3.
The volume of the compressed air is reduced, and the compressed air flows from the exhaust port 1a formed on one side surface of the communication plate 1 to the intake port 1 formed on the other side surface of the communication plate 1.
It flows into the second stage pump chamber 8 via b . At this time,
As mentioned above, the eccentricity of each impeller 5, 9 is changed,
Air flow rate ratio between the first-stage pump chamber 3 and the second-stage pump chamber 8
Is set appropriately, the pressure in the first-stage pump chamber 3
The compressed air whose volume has been reduced flows into the second-stage pump chamber 8.
Does not expand even when put in. And this air is
A state in which the volume is reduced by being further compressed in the second-stage pump chamber 8.
Is discharged from the second-stage pump chamber 8, and is discharged from the second-stage exhaust port 7a of the second-stage port plate 7 to the exhaust-side casing 6
Will be discharged to the outside through the exhaust port 6b of the exhaust side casing 6.

[0019]

Since the present invention is configured as described above, the ratio of the air flow rates of the first-stage pump chamber and the second-stage pump chamber can be made proper, and the inflowing air in the second-stage pump chamber can be adjusted. It is possible to prevent rapid expansion and prevent cavitation in the second-stage pump chamber. And thereby, various problems due to the occurrence of cavitation, were
For example, it is possible to reliably prevent the occurrence of erosion, increase in noise, and the like, and it is possible to provide a small-sized and highly efficient two-stage water-sealed vacuum pump. Further, since it has a relatively simple structure and can be easily manufactured, it is very effective as a vacuum pump of this type.

[Brief description of drawings]

FIG. 1 is a sectional view of a two-stage water-sealed vacuum pump to which the present invention is applied.

FIG. 2 is a front view of the communication plate shown in FIG.

3 is a front view of the second-stage side port plate shown in FIG. 1. FIG.

FIG. 4 is a front view showing an outline of both impellers shown in FIG.

5 is an explanatory diagram showing shapes and related positions of a second-stage pump chamber, a second-stage impeller, an intake port and an exhaust port shown in FIG.

[6] an explanatory view showing a comparison of FIG. 5, which shows the relationship position to the conventional shape.

FIG. 7 is a sectional view of a conventional two-stage water-sealed vacuum pump.

[Explanation of supplements]

A 2 stage water-sealed vacuum pump B 1st stage pump part C 2nd stage pump part 1a 1st stage pump chamber 3 exhaust port 1b 2nd stage pump chamber 8 intake port 3 1st stage pump chamber 5 1st stage Impeller 8 Second stage pump chamber 9 Second stage impeller 10 Rotating shaft O Center of first stage impeller 5 and second stage impeller P Center of first stage pump chamber 3 R Center of second stage pump chamber 8 s Second stage Eccentricity between the center R of the pump chamber 8 and the center O of the second-stage impeller 9 t Eccentricity between the center P of the first-stage pump chamber 3 and the center O of the first-stage impeller 5

Claims (1)

(57) [Scope of utility model registration request] 1. A first-stage impeller 5 provided in a first-stage pump chamber 3 and a second-stage impeller 9 provided in a second-stage pump chamber 8.
Are fixed to the same rotary shaft 10 and the exhaust port 1a of the first-stage pump chamber 3 and the intake port 1b of the second-stage pump chamber 8 communicate with each other. The eccentricity amount s between the center R of the second stage pump chamber 8 and the center O of the second stage impeller 9 is smaller than the eccentricity amount t between the center P of the chamber 3 and the center O of the first stage impeller 5. The structure of the pump chamber in the two-stage water-sealed vacuum pump characterized in that