JP2001289186A - Cooling device in screw fluid machinery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide spiral axial screw fluid machinery capable of efficiently cooling force-fed fluid in a casing by providing a means for cooling those parts other than a cooling water jacket thereon. SOLUTION: A cooling device is installed on spiral axial screw fluid machinery. The cooling device injects adiabatically expanded jet fluid to a casing, a delivery side cover, and a rotor shaft part thereof to directly and indirectly cool hot force-fed fluid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a spiral,
The present invention relates to a screw fluid machine, and more particularly, to a cooling device for preventing a pumping fluid generated by a compression action of a rotor mounted in a casing main body from becoming high in temperature.

[0002]

2. Description of the Related Art A conventional single screw, left and right same-shape, one-piece rotor, a spiral and screw fluid machine has a compressor. The compression ratio is limited to 3 and the gauge pressure is 2 kgf / cm ² or less. The internal fluid temperature accompanying the compression takes into account the cooling by the cooling water jacket of the casing. Thus, the temperature remains at about 120 to 130 ° C., and there is no problem. However, if this spiral or screw fluid machine is configured as a vacuum pump, one revolution of the screw meshing part on the suction side becomes the evacuation speed, and furthermore, the gas molecule motion between molecules using the rotating length of the screw lead part as a cubic container. Thus, a vacuum pump having a high compression ratio is configured to compress the fluid at the end screw engagement portion and increase the density of gas molecules. However, in the fluid compression structure having a high compression ratio, the temperature of the internal fluid is also around 200 ° C., and the rotor and the casing constituting these components also have a high temperature. In recent years, an internal compression type screw fluid machine that continuously reduces the lead volume toward the discharge side with the rotation of the rotor has been devised. However, if the total compression ratio is the same as the above-described structure, the internal fluid temperature can be reduced. At present, there is not much difference from about 200 ° C., and even in this configuration, a method for properly cooling the fluid temperature cannot be found at present.

[0003]

As shown in the prior art, the structure of a vacuum pump for a spiral or screw fluid machine using a pair of rotors having the same shape on the left and right sides with a single thread is different from that of a start end screw engagement portion to an end screw. Up to the meshing part, since it is a structure that constitutes a high compression ratio in a single stage continuous, one step, two steps, three steps are provided like a roots type vacuum pump,
A configuration in which each stage step is intercooled cannot be adopted. Furthermore, in the roots type vacuum pump, the internal fluid due to the rotation of the rotor moves in the inner circumferential direction of the casing due to centrifugal force, so that the internal fluid temperature is inevitably easily propagated to the inner wall of the casing, and the cooling effect of the casing cooling water jacket also works well. I do.
However, the internal fluid in the spiral or screw fluid machine is compressed and moved in the axial direction in the rotor groove, and is discharged from the side cover side surface through the terminal screw engagement portion. It is concentrated on the rotor, and has a fate configuration in which the temperature does not easily propagate to the inner wall of the casing.

[0004] As described above, a conventional spiral or screw fluid machine comprising a pair of rotors having the same shape on the left and right sides of a single-start thread, particularly a vacuum pump having a single-stage continuous high-compression ratio and an intercooler. In addition, it cannot be installed, and the internal fluid temperature is accumulated in the rotor groove due to the axial compression of the internal fluid, so that the temperature does not easily propagate to the inner wall of the casing. An object of the present invention is to reduce the internal fluid temperature without impairing the structure of the rotor in order to compensate for this disadvantage.

[0005]

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 left and right same shape, a pair of rotors, and a method for cooling an internal fluid temperature. Spiral, inert gas consisting of a small amount of overpressure,
A configuration is adopted in which the fluid temperature is cooled by adiabatically expanding the three necessary fluid spaces of the internal fluid pumping section, the fluid discharge chamber, and the rotor shaft section of the screw fluid machine.

[0006]

As described in the means for solving the problems, a single left and right same shape, a spiral composed of a pair of rotors,
In a vacuum pump of a screw fluid machine, an inert gas consisting of a gas with a diameter smaller than the atmospheric pressure is supplied at a normal temperature from a fixed point of a fluid pumping section casing into which a rotor on the inner wall of the casing is fitted without decompression, and the inert gas is formed in a small diameter. The aerosol expansion inside the fluid pumping section is performed by the aerosol nozzle, and the action of inducing a low-temperature gas is configured. This configuration is also provided at the side end of the discharge side cover fluid discharge chamber and the rotor shaft in addition to the above. In addition, a low-temperature gas is induced by adiabatic expansion to promote cooling.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The above operation will be described with reference to FIGS.
The reference example constitutes a spiral or screw fluid machine composed of an Archimedes curve and a Quimby curve. FIGS. 1 to 3 show a vacuum pump, and FIG. 4 shows both a vacuum pump and a compressor. In the example diagram, 1, casing,
2, a left rotor, 3, a right rotor, 4, a suction side cover, 5, a fluid pumping portion of a rotor screw lead, 7, a discharge side cover, and FIG.
A 'shows the view in the direction of the arrow A, and 6 denotes a boss for supplying an inert gas at a fixed point of the casing near the discharge side, 1A, penetrating through the casing cooling water jacket, 1B, and is formed on the inner wall of the casing. Reference numeral 9 denotes an inert gas supply pipe having an inner diameter S. The supply gas at 17 keeps the set pressure constantly supplied. Numeral 8 denotes a small-diameter fume nozzle, and numeral 20 denotes an adiabatic expanded inert gas. This configuration can also be applied to a spiral or screw fluid machine having a square screw shape.

Next, the cooling operation will be described with reference to FIGS. If the motor (not shown) rotates 3 and the right rotor rotates clockwise, the 2 and the left rotor rotate counterclockwise synchronously to the left. Due to this rotation, the fluid sucked from the fluid inlet is 10, and the screw lead on the spiral surface of the rotor
5. The fluid pumping section is pumped to the left, 10A, to the fluid discharge port, and the vacuum region connected to the fluid suction port achieves a high vacuum as shown in the prior art. However, the vacuum compression ratio in this process is about 1 Torr when the ultimate vacuum degree on the vacuum side is 2 leads, and the compression ratio r = Pd / Ps
= 760 Torr / 1 Torr = 760, and the vacuum pump has an internal temperature exceeding 200 ° C. at the left end of the fluid pumping section, even if the vacuum pump has the advantage of low fluid energy, unlike the compressor. Such high temperatures can cause chemical reactions and detonation in chemical specifications, which cannot be used as such and must be cooled. Now, in relation to 9, the supply gas to the inert gas supply pipe, and 8, the blast nozzle, the amount of gas blast from the nozzle is as follows. Assuming that the supply gas is 30 ° C. and the ultimate pressure degree is 1 Torr, the fluid pumping unit and the vacuum degree are −0.5 kgf / cm ² (380 Torr). Becomes This configuration will cause adiabatic expansion from the pressure of the supply gas to the fluid pumping section, The gas temperature can be determined. Now, Ts = supply gas temperature, 30
° C, Ps = 17, supply gas 5 kgf / cm ² , Pd = vacuum degree of fluid pumping section = −0.5 kgf / cm ² , m = adiabatic index 1.4, nozzle diameter = 1 mm, 8; When Td is calculated, it becomes -124.5 ° C., and in this case, in the previous case where the pumping speed of the vacuum pump was 800 l / m, the fluid internal temperature of 200 ° C. in one casing at the left end was mixed with the gas ejected from the blast nozzle. Thus, a high vacuum internal fluid is obtained, which is cooled to 175 ° C. and is significantly cooled from the internal fluid temperature generated by a conventional spiral or screw fluid machine.

Next, the configuration of FIG.
No gas supply boss is set 7;
C, the same 8B as the above-described configuration in the internal chamber, the blast nozzle 9B, the inert gas supply pipe 17, the supply gas is adiabatically expanded, and the 7C, the temperature in the internal chamber is cooled and reduced, 7, a configuration having an effect of cooling the ejection side cover is also shown. The calculation of the adiabatic expansion is the same as that described above, and will not be described.

Further, FIG. 4 shows a configuration 5 in which the rotors 2 and 3 are cooled without directly ejecting nozzles to the pumping fluid of the fluid pumping section in the rotor screw lead. , 15, gas supply pipe, 1
Reference numeral 4 denotes an ejection pipe, 16 and a nozzle, and 17 denotes a supply gas. 17, the supply gas is constantly maintained at the supply pressure, and the supply gas is adiabatically expanded from the nozzle of 14, the ejection pipe 16, so that the ejection gas from the 16 is 11, the cavity in the rotor is 18, and the inside of the rotor is indicated by an arrow. The U-turned inflated gas is released to the outside through the gap with the supporting adapter. Since this blast gas can generate extremely low temperatures as described above,
2, 3, the rotor can be cooled efficiently. Spiral and screw fluid machines pump fluid to the axial flow, so that compression heat is easily transmitted to the rotor. However, this cooling method is effective for cooling the rotor. At the same time, the cooling is applied to the pumping fluid of the rotor screw lead.

[0011]

As described above, according to the present invention, since the first and second aspects are a method of directly mixing a low-temperature gas into a pumping fluid to cool the temperature of the pumping fluid, extremely high-efficiency cooling can be performed instead of indirect cooling. . In addition, the gap between the casing and the rotor spiral surface is formed by mixing the jetted gas.
It is easy to construct a vacuum pump with a high degree of vacuum that can be sealed with the gas. According to the third aspect of the present invention, the supply gas does not require inertness and can use ordinary air. In all of the claims, the device itself is simple and can be mounted at low cost.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view of the spiral, screw fluid machine as viewed in the direction of arrows AA 'in FIG.

FIG. 3 is a longitudinal sectional view showing supply of cooling gas to a discharge-side gear case portion of the spiral and screw fluid machine according to the present invention.

FIG. 4 is a longitudinal sectional view showing a configuration for cooling a rotor of an Archimedean spiral spiral screw machine according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Casing 1A ... Casing cooling jacket 1B ... Casing inner wall 2 ... Left rotor 3 ... Right rotor 4 ... Suction side side cover 5 ... Rotor screw lead ... Inert gas supply boss 7 ... Discharge side cover 8, 8B ... Fume nozzle 9, 9B ... Inert gas supply pipe 10 ... Fluid suction port 11 ... ... cavity in rotor 12 ... support adapter 14 ... ... ejection pipe 15 ... gas supply pipe 16 ... nozzle diameter in ejection pipe 17 ... supply gas 18 ... arrow U Turn inflation gas 20 ... adiabatic expanded inert gas 7C ... internal chamber of discharge side cover d ... fume nozzle diameter S ... inert gas supply pipe inner diameter

Claims (3)

[Claims] A spiral fluid or screw fluid machine having a single left and right identical screw, a pair of rotors,
At the fixed point near the discharge side of the casing outer body, an inert gas supply boss is constructed through the cooling water jacket to the inner wall of the casing, and the inert gas supply pipe and the blast nozzle are formed on the boss, and the inert gas is formed. An inert gas that constantly maintains a set pressure is supplied to the supply pipe, adiabatic expansion is performed from the blast nozzle, and the expanded cold gas is injected into the pumping fluid in the fluid pumping section of the rotor screw lead, mixed, and cooled. Cooling device for spiral and screw fluid machines. 2. A screw fluid machine, comprising: a single left and right same-shaped screw; a spiral having a pair of rotors;
An inert gas supply pipe and a blast nozzle are formed on the discharge side cover, and an inert gas having a predetermined pressure is always supplied to the inert supply pipe, and the inert gas is adiabatically expanded from the blast nozzle. A cooling device for a spiral or screw fluid machine, characterized in that a cooled gas expanded and jetted and mixed with a discharge fluid in an internal chamber is cooled. 3. A screw fluid machine comprising: a single left and right identical screw; a spiral having a pair of rotors;
A rotor inner cavity is formed inside the rotor from the rotor shaft end,
A fumarole nozzle connected to the supply pipe is formed in the cavity inside the rotor, and a gas maintaining a set pressure is always supplied to the supply pipe, and the gas is adiabatically expanded from the blast tube nozzle to expand the cavity wall of the rotor. A cooling device for a spiral or screw fluid machine, characterized in that a cooled gas is injected and cooled.