JPS62189388A - Multistage roots type vacuum pump - Google Patents

Abstract

PURPOSE:To simplify assembling and to remove pipe connecting part so as to remove gas leakage by forming a communication passage to a suction port and a return passage leading to a pump chamber inside a casing so as to miniaturize and make compact outside dimension. CONSTITUTION:Communication passages 38, 41 are provided inside a casing 25 between the first pump chamber 12 and the second pump chamber 13 and communicate with suction ports 27, 32. Further return passages 51, 52, 53 which communicate with the first, the second and the third pump chambers 12, 13, 15 are provided beside discharge ports 22, 28, 33 positioned inside the casing 25. Since the communication passages 33, 41 and return passages 51, 52 are thus formed inside the casing 25, outside dimension can be made small and compact, trouble in assembling is small and there is no pipe connecting part, so gas leakage from these pipe connecting part can be get rid of.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a multi-stage roots-type vacuum pump in which the casing and rotor shaft of each stage are integrated.

[Prior art]

Conventionally, this type of multi-stage Roots type vacuum pump needs to cool the heat generated by gas compression in each pump chamber, and has a cooling path for cooling the heat. These cooling paths are piping installed outside the casing.
The structure is such that the piping is connected to each pump chamber.

[Problem that the invention seeks to solve]

However, since the conventional multistage roots-type vacuum bomb described above has a cooling path provided outside the casing, there are problems in that the outer diameter of the entire device becomes large and the assembly work is time-consuming.

Further, there were also problems such as gas leakage easily occurring at the piping connections.

The present invention has been made in view of the above-mentioned points, and provides a multi-stage Roots-type vacuum pump that solves the above-mentioned problems, has a small outer diameter, is compact, requires no assembly effort, and prevents gas leakage. The purpose is to

[Means for solving problems]

As a means for solving the above problems, the present invention provides the first
In a multi-stage Roots vacuum pump in which a plurality of sets of Roots vacuum pumps are arranged side by side with common rotor shafts and casings, and adjacent pumps are connected in series via a cooler and a communication path, the communication path is An opening is formed inside the casing and opens into the pump working chamber, and a return passage leading from the communication passage on the downstream side of the cooler to the opening in the working chamber of the preceding pump is provided inside the casing. As a second invention, a plurality of sets of roots-type vacuum pumps are arranged and combined with a common rotor shaft and casing, and adjacent pumps are combined. In a multi-stage Roots vacuum pump that is connected in series through a cooler and a communication passage, the communication passage is formed inside the casing and has an opening that opens into a pump working chamber, and the communication passage on the downstream side of the cooler is provided with an opening that opens into the pump working chamber. A return passage leading from the passage to the opening of the working chamber of the preceding pump is formed inside the casing, and the openings are provided at positions at different phases along the circumferential direction of the working chamber peripheral wall. It is an object of the present invention to provide a multistage Roots type vacuum pump characterized in that it is formed by individual openings.

[For production]

The first invention is that by configuring the multi-stage Roots type vacuum pump as described above, the communication passage and the return passage are formed inside the casing, so that the entire apparatus is compact and requires no effort to assemble. . Furthermore, since the communication passage and the return passage are formed inside the casing, there is no risk of gas leakage from the piping connection because the cooling passage is not piped outside the casing as in the conventional structure.

Further, in the second invention, since the opening of the return passage to the working chamber is formed by a plurality of openings provided at different phase positions along the circumferential direction of the working chamber peripheral wall, it is possible to prevent the return passage from passing through the cooler. Compared to ejecting gas from one opening at a time, the impact is reduced, making it possible to prevent vibrations, pulsations, noise, shock loads, etc.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

1 to 3 are diagrams showing the structure of a multistage Roots-type vacuum pump according to an embodiment of the present invention, and FIG. 1 is a longitudinal sectional view (however,
The rotational axis and rotor relationship are indicated by two-dot chain lines), and Figures 2 and 3 are on line I-I and n-am in Figure 1, respectively.
It is a top sectional view.

In FIGS. 1 to 3, 25 is a casing, which is divided into three working chambers by partition walls 11.14, namely, a first pump chamber 1
2. A second pump chamber 13 and a third pump chamber 15 are formed,
The whole structure is divided into two halves, top and bottom.

Inside the casing 25 are two rotating shafts 1 arranged in parallel.
6.17 is rotatably supported by a bearing 18, and the rotating shaft 16.17 has a first pump chamber 12, a second pump chamber 1
A pair of intermeshing roots-type rotors 26, 31, 36 housed in the third and third pump chambers 15 are fixed.

A driving means (not shown) is connected to the shaft end of one of the rotating shafts 16 passing through the shaft sealing device 20, and by rotating the rotating shaft 16 with the driving means, the timing gear 1
9, the rotating shaft 17 rotates in the opposite direction to the rotating shaft 16,
It is designed to rotate a roots-type rotor 26 degrees 31.36 degrees.

In addition, suction ports 21, 27° 32 and discharge ports 22, 28, 33 are formed in the first pump chamber 12, second pump chamber 13, and third pump chamber 15, respectively.

between the first pump chamber 12 and the second pump chamber 13, and between the second pump chamber 12 and the second pump chamber 13;
A communication path 38.41° is provided inside the casing 25 between the pump chamber 13 and the third pump chamber 15, and communicates with the suction port 27.32.

A passage 51.52.53 is provided beside the discharge port 22.28.33 across the partition wall 50, and the passage 51.52.53
are connected to the first pump chamber 12. by openings 23, 29, and 34, respectively. The second pump chamber 13° communicates with the third pump chamber 15. At the same time, the passages 51, 52, 53 are equipped with coolers 39,
Communication path 38.41 and connection path 46 on the downstream side of 42.45
It is familiar to

As shown in FIG. 2, a plurality of openings 23 are provided at different positions along the circumferential direction of the peripheral wall of the first pump chamber 12 (in the figure, three openings are provided in each of the peripheral walls where the pair of rotors 26 are located). There is. Similarly, a plurality of openings 29.degree. 34 are provided at different positions along the circumferential direction of the peripheral walls of the second pump chamber 13 and the third pump chamber 15, respectively.

Also, 39, 42, and 45 are cooling coils 54.5 and 54.5, respectively.
5.56, the cooler 39.42.
45 are respectively connected to the outlet ports 22, 28, 33 by connecting passages 37, 40° 43, and connecting passages 57, 58.
46 connects the communication path 38 to 41 and 53.

As described above, the vacuum pump is a roots-type vacuum pump of 3&Il equipped with a rotor 26.3L36, a cooler 39,
This is a multi-stage Roots type vacuum pump which is connected in series through 42, 45 and communication passages 38, 41.

In addition, in the figure, 59 is a suction port communicating with the suction port 21,
44 is a discharge port communicating with the cooler 45 and the connection path 46.

The operation of the multi-stage Roots type vacuum pump having the above structure will be explained below.

The gas sucked in through the suction port 59 flows into the first pump chamber 12.
The pump is transferred to the cooler 39 by the rotor 26, cooled by the cooler, and then supplied to the second pump chamber 13 through the communication passage 38 through the suction port 27. At the same time, a part of the gas cooled by the cooler 39 enters the return passage 51 through the communication passage 38,
It is returned to the first pump chamber 12 through the opening 23. Rotor 2
6, the gas in the first pump chamber 12 is compressed and its temperature rises, but it is cooled by the cooler 39, returned to the gas, and is cooled by the gas ejected from the opening 23, thereby preventing the temperature from rising.

The gas supplied to the second pump chamber 13 is transferred to the cooler 42 by the rotor 31, cooled by the cooler 42, and enters the third pump chamber 15 through the communication passage 41 and the suction port 32. A part of the cooled gas enters the return passage 52 from the communication passage 41 and is ejected from the opening 29 into the second pump chamber 13.
The gas in the second pump chamber 13 whose temperature increases due to compression is cooled.

Similarly, the gas exiting the second pump chamber 13 is transferred to the cooler 45 by the rotor 36, cooled and discharged from the discharge port 44, but a part of it enters the return path 53 from the connection path 46 and enters the 34 into the third pump chamber 15, and cools the high temperature gas which is compressed and heated within the third pump chamber 15.

By the way, in the multi-stage Roots type vacuum pump having the above structure, as described above, the openings 23.29° 34 have a phase difference along the circumferential direction of the peripheral wall of the first to third pump chambers 12.13° 15, respectively. Since a plurality of pump chambers are arranged at different positions, each of the first to third pump chambers 12, 13 .
When the gas cooled by the cooler 39.42.45 is returned to the cooler 39.45, the rotors 26, 31.36 are opened sequentially as they rotate. Shock is alleviated, vibration, pulsation,
It prevents noise and shock loads from occurring, makes the mixture of gas jets uniform, alleviates local temperature changes, and prevents deformation, leakage, etc. Further, the multi-stage roots type vacuum pump has a communication passage 33.41, a return passage 51, 52.53
is formed inside the casing 25, so the outer diameter can be made small and compact, and assembly is not labor-intensive, and since there are no piping connections, there is no fear of gas leaking from these piping connections.

Note that the above embodiment is one embodiment of the present invention, and the multistage Roots vacuum pump of the present invention is not limited to this. (In short, in the first invention, the gas passing through the cooler It is only necessary that a part of the pump is returned to the working chamber of the preceding pump via the passage, and in the second invention, the communication passage and the return passage are formed inside the casing, and the working chamber of the return passage is If the opening to is formed by a plurality of openings provided at different phase positions along the circumferential direction of the working chamber peripheral wall, for example, the number of stages, structure, etc. of the Roots-type vacuum pump are as described above. The present invention is not limited to the multi-stage Roots type vacuum pump having the structure shown in FIGS. 1 to 3.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to provide a multi-stage Roots type vacuum pump which has extremely excellent practical effects as shown in the above.

(2) In the first invention, since the communication passage and the return passage are formed inside the casing, the outer diameter is small and compact, the assembly requires no effort, and there is no gas leakage.

In the second invention, part of the gas that has passed through the cooler is returned to the working chamber of the preceding pump via the passage, and the opening of the return passage to the working chamber is It is formed by multiple openings provided at different phase positions along the circumferential direction of the chamber wall, so it reduces shock, prevents vibrations, pulsations, noise, and shock loads, and reduces local temperature. Changes are alleviated and deformation does not occur.

[Brief explanation of drawings]

1 to 3 are diagrams showing the structure of a multistage Roots-type vacuum pump according to the present invention, and FIG. 1 is a longitudinal cross-sectional view (however, the rotation axis,
The rotor relationship is indicated by the two-dot chain line), Figures 2 and 3.
The figures are I-! of Figure 1, respectively. It is a sectional view on the line and on the line ■-■. In the figure, 11... partition wall, 12... first pump chamber, 13
...Second pump chamber, 14...Partition wall, 15...Third
Pump chamber, 16... Rotating shaft, 17... Rotating shaft, 18
... bearing, 19 ... timing gear, 20 ... shaft sealing device, 21 ... suction port, 22 ... discharge port, 23 ...
...Opening, 25...Casing, 26...Rotor,
27... Suction port, 2nd... Discharge port, 29... Opening, 31... Rotor, 32... Suction port, 33... Discharge port, 34... Opening, 36...・Rotor, 37...
Connection path, 38... Communication path, 39... Cooler, 40.
...Connection path, 41...Communication path, 42...Cooler, 4
3... Connection path, 44... Discharge port, 45... Cooler, 46... Connection path, 50... Partition wall, 51.52.5
3... Passage, 54°55.56... Cooling coil, 5
7.58... Connection path, 59... Suction port.

Claims (2)

[Claims] (1) In a multistage roots-type vacuum pump in which a plurality of sets of roots-type vacuum pumps are arranged side by side and have a common rotor shaft and casing, and adjacent pumps are connected in series via a cooler and a communication passage, the communication passage is An opening is formed inside the casing and opens into the pump working chamber, and a return passage leading from the communication passage on the downstream side of the cooler to the opening in the working chamber of the preceding pump is provided inside the casing. A multi-stage roots-type vacuum pump characterized by the (2) In a multistage roots-type vacuum pump in which a plurality of sets of roots-type vacuum pumps are arranged side by side and have a common rotor shaft and casing, and adjacent pumps are connected in series via a cooler and a communication passage, the communication passage is An opening is formed inside the casing and opens into the pump working chamber, and a return passage leading from the communication passage on the downstream side of the cooler to the opening in the working chamber of the preceding pump is provided inside the casing. A multi-stage Roots vacuum pump characterized in that the opening is formed by a plurality of openings provided at different phase positions along the circumferential direction of the working chamber peripheral wall.