JP2001193677A - Screw fluid machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spiraxial screw fluid machine for compressing suction fluid by a thread lead part inscribing with a casing when transferring the fluid from a suction side to a delivery discharge side within the casing, thereby obtaining a higher degree of vacuum and higher pressure and also a lowered final discharge temperature compared with a conventional arrangement. SOLUTION: This spiraxial screw fluid machine internally compresses at a plurality of stages by different thread leads from the suction to the rotor end fallowing rotation of the rotor in the area between the spiral surface of the rotor and a corresponding fluid space. Because of a compressing mechanism formed in the thread lead part, a high degree of vacuum and a high pressure can be secured, compared with a conventional spiraxial screw fluid machine. If the number of leads remains the same, the overall length of the rotor can be shortened compared conventional one.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spiral screw fluid machine having improved rotor mounted in a casing body and maintaining a high compression ratio in a casing stroke.

[0002]

2. Description of the Related Art In a conventional structure of a spiral screw fluid machine having a single-threaded screw, a left-right same shape, and an integral rotor, in a configuration as a compressor, one rotation of a meshing portion of a suction side and a start end becomes a displacement amount. The screw lead portion has a configuration in which the compressed and pressurized fluid is discharged for the first time at the discharge side and the terminal screw engagement portion without the compression mechanism only for transfer. In addition, the structure of the vacuum pump is such that one rotation of the screw engagement portion at the start end of the rotor is used as the exhaust speed, a plurality of screw leads having no compression mechanism are used, and the length of the screw lead is a cubic container. Vacuum pumps have been constructed by increasing the density of gas molecules by moving and compressing the fluid at the terminal thread engagement portion.

[0003]

As shown in the prior art, a single screw thread is used as a compressor of a spiral screw fluid machine with a pair of rotors of the same shape on the left and right sides, and a compression mechanism is provided at the end screw engagement portion. With only one rotation,
Compression ratio 3 is the limit. If the compression ratio is further increased, the volumetric efficiency will be extremely reduced and the compression temperature will increase, causing an accident in which the outer diameter of the rotor and the inner circumference of the casing come into contact.
To prevent this, if the clearance between the outer diameter of the rotor and the inner circumference of the casing is increased, then the suction fluid becomes hot before the high-temperature discharge fluid flows back to the suction side and compresses the fluid at the terminal screw engagement part. Further, the vicious circulation at which the compression temperature becomes high induces and promotes contact between the rotor outer diameter and the spiral surface.
Therefore, the compression ratio is limited to 3 as described above. Therefore, compression at a gauge pressure of 2 kgf / cm ² or more was impossible.

[0004] In the following configuration of the screw fluid machine as a vacuum pump, the number of screw leads of the rotor is set to 4 to 6, and the vacuum pump can be configured with one rotation of the screw engagement portion at the start end as the exhaust speed. 1 Pa (7.5 × 10 ⁻³ To
In order to secure a vacuum of rr), a plurality of screw leads are configured so that gas molecules can move as a cubic container, and the degree of vacuum is maintained by the compressing action of the terminal screw. Therefore, this screw lead portion cannot form a cubic container unless the clearance between the spiral surface of the rotor outer diameter and the inner periphery of the casing is minimized and the fluid does not flow backward from the spiral surface to the suction side. That is, it cannot be a cubic container that secures gas molecule motion between molecules or between molecules and the wall of a cube. In order to construct such a cubic container, it is required to perform processing with high precision in the processing accuracy of the rotor and casing, and also to force the processing by spraying a lining material after the processing. Further, since the compression action for generating a high vacuum by increasing the density of gas molecules is provided only at the terminal screw engagement portion, the compression ratio near the terminal portion becomes excessively large and the discharge temperature rises rapidly. The fluid having the increased temperature flows backward from the clearance of the rotor spiral surface to the entire suction side, and has a drawback that the clearance has to be increased by expansion due to a vicious circulation in which the temperature of the suction fluid is increased and recompression is performed. . For this reason, an excessive cost is required to secure a vacuum of 1 Pa, and it is difficult to achieve a high vacuum of 1 Pa or more at present.

As described above, in the conventional spiral screw fluid machine constituted by a pair of rotors having the same shape on the left and right of a single thread, the screw lead portion does not have a compression mechanism, and therefore an excessive compression load is applied to the terminal screw engagement portion. At the same time, there is a disadvantage that the high temperature fluid at the terminal end flows straight back to the suction side. An object of the present invention is to provide a compression mechanism in the screw lead portion in order to compensate for this disadvantage.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is directed to a spiral screw fluid machine having a single left and right same shape, a pair of rotors.
In order to secure the required compression ratio or vacuum ratio for the entire length of the rotor, the fluid space formed by the plurality of screw leads is moved from the suction position of the start screw engagement portion to the discharge position of the end screw engagement portion in the end direction. A mechanism is adopted in which the rotor has a compression structure for reducing the volume of the fluid space according to the number of screw stages formed by different screw leads.

[0007]

As shown in the means for solving the problems, in a spiral screw fluid machine comprising a pair of rotors having the same shape on the left and right sides, a spiral screw surface of the rotor and a groove portion are formed. Between the fluid space enclosed at the suction position of the portion and the fluid space before the discharge position of the terminal screw engagement portion, a fluid space having a cubic volume constituted by the screw lead portion is formed in a plurality of stages toward the terminal direction. With different screw leads, the volume of the fluid space can be compressed and reduced in multiple stages,
By configuring the compressor with a compression structure that maintains the final compression ratio in the rotor, a fluid space having a volume ratio of 3 can be formed by this screw lead portion in the compressor. 9 kgf / cm, which was impossible with a single-rotation left and right identical paired rotor
The oil-free fluid having a discharge pressure of ² G can be easily used by increasing its pressure.

[0008] Further, as the vacuum pump, the space maintained by the plurality of screw leads is a cubic container, and the function of maintaining the initial vacuum degree by the gas molecule motion and further using a plurality of different screw leads formed by the rotor spiral surface. By reducing the volume of the suction fluid space in multiple stages, a compression ratio of 3 to
4 and high-density gas molecules can be secured by the end of the screw lead to ensure a high degree of vacuum. In addition, the target 1 Pa (7.5 × 1)
0 ^-3 Torr) has an action that can achieve high degree of vacuum higher.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction will be described with reference to FIGS. The reference example is a configuration example as a vacuum pump of a spiral screw fluid machine composed of an Archimedes curve and a Quimby curve, and FIG. 1 shows a screw vacuum pump having the structure of the present invention. FIG. 3 shows an assembly structure in which the volume of the fluid space is compressed to a required compression ratio in three stages by different screw leads as the volume of the fluid space approaches the terminal screw engagement portion due to the rotor spiral surface in the portion. 1 to 3, 1 casing, 2 left rotor and 3 right rotor are shown, 4a is a suction side rotor spiral surface, 4a to 4b, an intermediate rotor spiral surface, and 4c a discharge side rotor spiral surface and a small screw lead. Thus, the left and right rotors are configured. 5a is a suction fluid space, 5b is an intermediate fluid space in the 4b screw lead, and 5c is a discharge-side fluid space of the screw lead end 4c. Reference numeral 7 denotes a discharge-side side cover having 11 discharge holes. 8
Is a suction side cover, 9 is a fluid suction port, and 10 is a fluid discharge port. Fig. 2 shows the right rotor and the number of screw leads is 9
4a suction side rotor spiral surface is 4b,
The width becomes smaller in three stages as it approaches 4c and the fluid discharge port. And the suction side screw lead of the S ₁ is shorter the discharge side thread lead of the S ₃ from the intermediate thread lead of the S ₂ is accompanied.
At the same time, the suction fluid space 5a is compressed from the intermediate fluid space 5b to the discharge fluid space 5c. FIG. 3 shows a side view of the right rotor of FIG.
A screw tooth profile that is configured by C ₁ Archimedes curve and C ₂ Quimby curve and C ₃ yen. Figure 4 shows a screw vacuum pump having a conventional structure, FIG. 5 is the same, represents a right rotor indicates that S ₁ suction side screw lead and S ₃ discharge side thread lead is the same size.

Next, the rotation operation will be described with reference to FIGS. If the motor (not shown) rotates 3, the right rotor rotates clockwise, and the left and right rotors rotate counterclockwise synchronously with the right rotor 2 by the interlocking of the drive and driven gears. By this rotation, 9
Fluid sucked from the fluid inlet port, a suction fluid space 5a partitioned by a screw lead 4a suction side rotor spiral surface, between 5c discharge side fluid space, 5a suction fluid space in S ₁ suction side screw lead While moving the cubic volume as one container to the discharge side, the degree of vacuum is raised by collision fluid molecular motion between the fluid molecules and between the molecules and the wall of the 6 cubic volume. 2,3 rotor 4a suction side rotor spiral surface 4b, with width becomes narrower in three steps as shown in 4c, S ₂ at the same time the suction side screw lead also three stages S ₁
In this case, the intermediate screw lead of No. ₃ is reduced to the discharge side screw lead of S3. Therefore, the volume of the 5a suction fluid space has a compression ratio of 3 to create a high degree of vacuum.
Constitute the stage, the compressed to the volume of 5c discharge side fluid space, cubic volume of the S ₁ suction side thread lead of 5a is while reducing the volume in three stages by different screw lead,
The suction fluid is moved to the discharge side and the fluid is compressed at a large compression ratio, so that a further degree of vacuum can be added. This high-vacuum fluid is once again compressed by the terminal screw engagement portions of the two or three rotors, and can produce a high vacuum several steps higher than the vacuum of the 5c discharge-side fluid space. A significantly higher vacuum than that obtained from a screw fluid machine can be obtained.

When the screw fluid machine is configured as a compressor, the volume of the suction fluid space of 5a is compressed in three stages through the intermediate fluid space of 5b as it approaches the terminal screw engagement portion, and the volume of the 5c discharge side fluid is reduced. Since it is easy to secure the compression ratio of 3 or more because of the volume of the space, this operation is set as one stage at the initial stage, and the compression ratio at the end screw engagement part is set at two stages.
7kgf which is the most used oil-free fluid
It is easy to use a fluid with a discharge pressure of / cm ² G. It is not necessary to form a fluid space as a cubic container such as a vacuum pump. Next, FIG. 6 shows a conventional spiral screw fluid machine having a pair of rotors having the same shape of left and right screws having a square screw shape. This rotor also has a few screws in the same manner as the aforementioned Archimedes-Quinby curve rotor. the rotor is different 4a suction side rotor spiral surface by screws leads 4b, 4c and multiple stages so width becomes narrower, and at the same time the suction side screw lead of the S ₁ is S ₂
Processing the intermediate thread lead in stepwise smaller configuration and S ₃ the discharge side screw lead, by creating, it can form a screw fluid machine of a high compression ratio.

[0012]

As described above, according to the present invention, the volume of the fluid space defined by the spiral surface and the corresponding groove portion is compressed and reduced in a plurality of stages by different screw leads as the rotor approaches the terminal screw engagement portion. Since the screw is created in the structure to perform the compression and the pressure is further increased at the end screw engagement portion, the discharge pressure is 7 kgf / cm ² G for the compressor, and 1 Pa (7.5 for the vacuum pump to which the fluid molecular motion is added.
× 10 ⁻³ Torr) or more can be easily secured. In addition, since the screw lead inside the casing, the terminal screw engagement portion and the compression mechanism are divided, the discharge temperature can be kept low when used with the same specifications as compared with a conventional screw fluid machine. Since the screw lead dimensions are shorter at the center and immediately before the terminal screw engagement portion, when the number of screw leads is the same, the rotor length can be shorter than that of a conventional screw fluid machine.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a spiral screw fluid machine having an Archimedes-Quinby curve according to the present invention.

FIG. 2 is a right rotor diagram of a spiral screw fluid machine having an Archimedes-Quinby curve of the present invention.

FIG. 3 is a right rotor side view of the spiral screw fluid machine having the Archimedes-Quinby curve of the present invention.

FIG. 4 is a longitudinal sectional view of a spiral screw fluid machine having an Archimedes-Quinby curve of a conventional structure.

FIG. 5 is a right rotor diagram of a spiral screw fluid machine having an Archimedes-Quinby curve of a conventional structure.

FIG. 6 is a longitudinal sectional view of a casing and a rotor of a conventional spiral screw fluid machine having a square screw shape.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Casing 2 ... Left rotor 3 ... Right rotor 4a ... Suction side rotor spiral surface 4b ... Intermediate rotor spiral surface 4c ... Discharge side rotor spiral surface 5a ... Suction fluid space 5b ... Intermediate fluid space 5c ... Discharge side fluid space 6 ... Cubic volume wall 7 ... Discharge side cover 8 ... Suction side cover 9 ... Fluid suction port 10 ... Fluid discharge port 11 ... Discharge hole S ₁ ... Suction side Screw lead S ₂ … Intermediate screw lead S ₃ … Discharge side screw lead C ₁ … Archimedes curve C ₂ … Quinby curve C ₃ … Circle L

Claims (2)

[Claims] 1. A spiral screw fluid machine having a pair of left and right identically threaded rotors having a tooth profile consisting of an Archimedes curve and a Quimby curve,
In the left and right rotors, the required volume ratio between the volume of the suction fluid space and the volume of the screw thread at the beginning, and the volume of the fluid space immediately before, at the beginning, is configured in multiple stages by a plurality of different screw leads. Then, by rotating the rotor between the rotor spiral surface of the screw lead and the cubic volume of the corresponding groove, the volume of the suction fluid space moves to the terminal screw engagement portion and the volume required in a plurality of stages A spiral screw fluid machine characterized by creating a rotor screw in a configuration that compresses and reduces the volume of the discharge-side fluid space at a specific ratio. 2. A spiral screw fluid machine having a pair of left and right right-hand threaded rotors having a tooth shape of a square thread shape, wherein the left and right rotors have a starting fluid in a suction fluid space. The required volume ratio between the volume and the terminal screw engagement portion, the volume of the discharge-side fluid space immediately before, is configured in a plurality of stages by a plurality of different screw leads, and the cube of the groove corresponding to the rotor spiral surface of the screw lead As the volume of the suction fluid space moves to the terminal screw engagement by rotating the rotor between
A spiral screw fluid machine in which a rotor screw is created to compress and reduce the volume of a discharge-side fluid space to a volume ratio required in a plurality of stages.