KR0152174B1 - A continuous compressing type screw pump - Google Patents

Abstract

SUMMARY OF THE INVENTION An object of the present invention is to provide a highly efficient continuous compression multistage screw type vacuum pump having a very simple structure and miniaturization by removing the partitions between the screw stages and the inlet and discharge ports provided separately for each stage. .

In order to achieve the above object, a configuration of the present invention provides a multistage screw vacuum pump in which a plurality of stages are arranged in series on a pair of main shafts and driven shafts, and the screw stages of the plurality of stages have different screw lead lengths. After being processed as a separate object, the end faces of the main shaft and the driven shaft are fitted to be fixed so as to contact each other, but the screw of the plurality of stages is assembled in order of decreasing thread lead length from the pump suction side to the discharge side. It is done.

Description

Continuous Compression Multistage Screw Vacuum Pump

1 is an explanatory diagram of a screw rotor of a continuous compression type multistage screw vacuum pump of the present invention.

2 is a cross-sectional view of a continuous compression multistage screw vacuum pump of the present invention.

3 is an explanatory diagram of a conventional two-stage screw type rotor.

4 is a cross-sectional view of a conventional two-stage screw type vacuum pump.

5 is a cross-sectional view of a conventional single stage Roots vacuum pump.

6 is a front view of a conventional opposed two-stage Roots type vacuum pump.

7 is a longitudinal sectional view of a conventional multistage Roots type vacuum pump.

8 is an explanatory diagram of a two-stage vacuum pump.

* Explanation of symbols for main parts of the drawings

41: main screw rotor 42: coarse screw rotor

43: main shaft 44: driven shaft

45,46: 1st stage screw 47,48: 2nd stage screw

49,50: Third stage screw 51,52: End face

53: suction port 54: discharge port

55: fixing means 56: pump casing

57,58: Timing Gear

[Industrial use]

The present invention relates to a multistage screw vacuum pump of a continuous compression type designed to be continuously compressed by designing a multi-stage screw rotor part on one main shaft and a driven shaft and removing the partition wall between the stages and stages.

Conventional Technology and Problems

Recent advances in vacuum technology have been surprisingly fast, and their applications are spreading to semiconductor deposition, electronics, metal chemistry, pharmaceuticals, and nuclear power.

In addition, there are many types of vacuum pumps that produce a vacuum, such as a water seal type, a rotary type, a Root-type type, a diffusion type, a physical adsorption type, and a chemical adsorption type, but can be divided into wet and dry types.

However, wet type (water or oil injected into vacuum pump) such as water seal type or rotary type is not gradually used in industrial fields such as semiconductor, food, chemical, and pharmaceutical industries that aim to absorb impurities, and therefore dry (water in pump). Vacuum pumps with no oil or oil) have been used in automobiles.

However, in the case of volumetric dry vacuum pumps, it is difficult to reach this in one stage when used for suction of 400 Torr (-0.5kg / cm ² G) or less, and the number of stages of the vacuum pump is usually By increasing the pressure ratio per stage, the heat generation of the vacuum pump is suppressed.

However, if the number of steps of the vacuum pump increases, the number of parts attached to it and the number of parts, such as a motor, of course increase, resulting in a problem of raising the cost, and thus a disadvantage that the installation area of the pump is also inevitable is inevitable.

Among several pumps, in the Lutz type, a miniaturized vacuum pump of multiple stages can be obtained on the market.

The conventional single-stage Roots-type vacuum pump connects the coupling from the motor output shaft to the peanut-type ro-ta (2) at approximately the center of the rotationally driven shaft (1) as shown in FIG. Homorotary and pilot gears of the same type, which engage the rotatables (2) in the same shape on a driven shaft (not shown) that holds the pilot gear (3) at one end and is placed parallel to the shaft (1) (3) secures the number of teeth of the same number of teeth to be combined to form a rotating portion, and the pair of rota outer left and right sides sealed with a casing (4), side case (5) and side case (6) It is a vacuum pump for discharging the gas sucked from the suction port 7 by the pair of rotatable rotation to the discharge port (8).

Here, reference numeral 9 denotes a gear case covering the pilot gear 3 and the like, and reference numeral 10 denotes an axis bearing portion for supporting the shaft 1.

In the case where the Roots-type vacuum pump configured as described above has two stages, two pumps A and B are arranged facing each other with respect to the motor 11 as shown in FIG.

Accordingly, the flow of the sucked gas is discharged from the discharge port 13 from the inlet 12 of the first stage pump A, and after cooling the compressed heat via the cooler 14, the second stage pump B After entering the suction port 15 of the compressed and conveyed is discharged to the discharge port (16).

In such an opposite type, since it is possible to drive the shaft 1 of both pumps (A) and (B) with one motor-11, nothing is obtained except reducing the number of gears of one motor.

Recently, a multi-stage Roots-type vacuum pump as shown in FIG. 7 has been proposed and used.

This arranges the first stage rotor 18, the second stage rotor 19, and the third stage rotor 20 on one shaft 17 to seal between the respective rotors 18, 19, and 20. It consists of installing a partition.

The gas to be sucked is the third stage discharge port via the first stage suction port 21, the first stage discharge port 22, the second stage suction port 23, the second stage discharge port 24, and the third stage suction port 25. Discharged to (26).

Therefore, by arranging the rotors of equally divided widths on the two main and driven shafts corresponding to the pressure ratio, it is possible to simply concentrate the rotors of the plurality of stages, thereby reducing the number of parts and reducing the required installation area. Was obtained.

The same principle applies to the screw-type vacuum pump, which is more efficient than the Lutz type, by applying the same method to the screw type multi-stage vacuum pump with a partition wall between the screw stages. ), Which is shown in FIG.

The invention of the above-described proposals has the screw sections 29, 30, 31 and 32 having outer diameters D _a1 and D _a2 , respectively, with a distance l ₁ on the main and driven shafts 27 and 28. ) Is divided into two parts by the partition member 35 inserted into the space (l ₁ ) when assembled to the case (33) (34).

The reason why the space l ₁ is provided between the first stage screw portions 29 and 30 and the second stage screw portions 30 and 31 so as to install the partition member 35 is that the two screw portions provided on one shaft are respectively provided with an outer diameter and a diameter. This is due to the fact that continuous machining is impossible because of different pitches. However, the screw vacuum pump having such a structure is excellent in vacuum efficiency, but the partition member 35 must be installed between the stages and the inlets 36 and 38 and the outlets 37 and 39 must be separately provided for each stage. It is pointed out that it is insufficient to meet the requirements of a vacuum device such as a semiconductor manufacturing facility which requires both a small installation area and high vacuum efficiency due to an increase in the number of parts, a complicated structure of the casing, and a large installation area. It is becoming.

[Problem to Solve Invention]

The present invention has been made in view of the above problems of the multistage screw type vacuum pump, and its purpose is to eliminate the partitions between the screw stages and the stages, and to remove the inlets and outlets provided for each stage. To provide a high efficiency continuous compression multistage screw type vacuum pump.

[Means for solving the problem]

The configuration of the present invention for achieving the above object is a multi-stage screw type vacuum pump in which a plurality of stages are arranged in series on a pair of main shaft and a driven shaft, the screw of the plurality of stages each has a screw lead length After being machined to be different, it is fitted and fixed so that its end faces come into contact with the main shaft and the driven shaft, but the screws of the plurality of stages are assembled in the order of decreasing the screw lead length from the pump suction side to the discharge side. It features.

EXAMPLE

Hereinafter, with reference to the accompanying drawings an embodiment of the present invention will be described in detail.

1 is a view showing an embodiment of a screw rota in accordance with the present invention, Figure 2 is a view showing a continuous compression multi-stage screw vacuum pump equipped with an in-phase screw rota.

First, prior to the description of the configuration of the present invention, the theoretical basis and concept of the two-stage vacuum pump will be described with reference to FIG.

In the first stage pump (A), the suction pressure, suction side temperature (absolute temperature), air flow rate and pressure ratio are set to P ₂ , T ₂ , Q ₂ , γ ₂ , and the gas discharged from the first stage pump A is At the inlet of the second stage pump B via the cooler 14, the middle ratio, the intermediate temperature, the middle air volume, and the pressure ratio of the second stage pump B are P _m , T _m , Q _m , and γ ₁ . Ignoring the pressure loss, the following relation holds.

That is, when the suction ratio between the first stage is T ₂ and the pressure ratio is γ _1, the air volume of the first stage pump becomes Q ₂ when the temperature of the second stage is T _m and the pressure ratio is γ _2. It needs to be like this (2).

Therefore, between the first stage and the second stage, of course, the theoretical air volume is different, and Q ₂ ≠ Q _m , and the specifications of the screw rotor are not the same.

As is well known in the prior art, it is not possible to combine screw row-coating on the same axis if the screw row-taking specifications are different. Naturally, screw row-taking could be combined if the following relation was satisfied (see FIGS. 3 and 4).

When the above formula (3) is satisfied, it is possible to combine screws having different air flow rates on the same axis.

The present invention is a critical difference from the prior art is that the present invention is to remove the intermediate partition 35 installed in Figure 4 of the conventional type to enable continuous compression of Figure 1 of the continuous compression type multi-stage screw vacuum pump of the present invention The d and D of the screws are the same, and the lead is changed by a certain ratio, so that a plurality of screws are connected in series so that they can be continuously compressed.

In Figure 1,

Therefore, the air volume ratio is proportional to each lead length. That is, when the lead length is longer, the air volume increases, and when the lead length is short, the air volume decreases in proportion to L ₁ L ₂ L ₃ and Q ₁ Q ₂ Q ₃ continuously. Compression is now possible.

The specific structure of this invention is demonstrated below.

The main and driven shaft screw rotors (41, 42) of the present invention is a rotary shaft (43), 44, first stage screws (45), 46, second stage screws (47) (48) and third stage screws (49) (50)... It consists of a plurality of stages. The rotating shaft and the screw of the plurality of stages are processed as separate separators, respectively, and then assembled by fitting the shaft and the holes. The screw 45, 47, 49, 46, 48, 50 of the plurality of stages are machined with different lengths of thread leads, and their outer diameters D and bone diameters d are all the same. As for the number of threads (lead number) of the screw of each said stage, about 2-4 pieces are preferable.

The main shaft screws (45, 47, 49), each machined to have a thread lead L ₁ , L ₂ , L ₃ in a CNC lathe, etc., may be fitted to the end faces (51) (52) of the main shaft (43) in contact with each other. Fixing means 55, e.g., key or pin member, in order that the leads L ₁ , L ₂ , L ₃ are larger so as to be located toward the pump inlet 53 and smaller groups are located toward the pump outlet 54. Fix onto shaft (43).

In the same way, the driven shaft screws 46, 58, and 50 are assembled by fitting the driven rotation shaft 44 through the center hole thereof, and then the teeth of the main and driven screw motors 41 and 42 are engaged to pump. It is housed tightly in the casing 56.

Accordingly, when the motor is driven, the main rotating shaft 43 rotates, and the driven rotating shaft 44 engaged by the timing gears 57 and 58 rotates together, so that the two main and driven screw rotors 41 and 42 rotate. It rotates while being engaged.

When the screw rotors 41 and 42 are engaged, the gas is sucked out of the vacuum equipment not shown through the pump inlet 53 and compressed while passing through the first stage screws 45 and 46, and the volume is smaller. The paper is compressed while passing through the second stage screws 47 and 48 and the third stage screws 49 and 50 and then discharged through the discharge port 54.

[effect]

As described above, the present invention processes a plurality of screws having different leads into separate pieces, and then uses a plurality of screws to contact each other on a pair of main shaft and driven shaft in order of decreasing lead from the pump suction port side to the discharge port side. By fitting and fixing with a key, it is possible to omit the bulkhead between the stages and the inlet and outlet ports provided at each stage, making the structure extremely simple, miniaturizing the size, and greatly improving the vacuum capability. have.

Claims (2)

In a multistage screw type vacuum pump in which a plurality of screws are arranged in series on a pair of main shafts and a driven shaft, the screws of the plurality of stages are machined separately to have different thread lead lengths, and then the main shaft and The screw of the plurality of stages is a continuous compression type multi-stage screw vacuum pump, characterized in that the screw lead length is assembled in decreasing order from the pump suction side to the discharge side. The continuous compression type multistage screw vacuum pump according to claim 1, wherein the plurality of screws are fixed on the main shaft and the driven shaft by means of fastening means by keys or pins.