JP2006118417A - Screw compressor for ammonia - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a screw compressor for ammonia making ammonia resistant measure of a stator of a motor unnecessary, eliminating danger of leak of ammonia to an outside of a machine, and having good performance. <P>SOLUTION: In the screw compressor 1A for ammonia having a compressor casing 15 of a compressor main body 13 including a drive side and a driven side screw rotor 11, 12, and a motor casing 16 of the motor 14 which is a drive part connected as one unit, having a rotor shaft 17 of the drive side screw rotor 11 and an output shaft 18 of the motor 14 directly connected, and having the output shaft 18 supported at only the rotor shaft 17 side, the motor 14 is positioned below the compressor main body 13 and they are vertically arranged and an intake port 21 of the compressor main body 13 is formed in the motor 14 side, a terminal part 25 for supplying electric power to a stator coil of the motor 14 and a coil end 26 of the stator coil is immersed in oil which is not compatible with ammonia gas and has specific gravity larger than ammonia liquid. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a screw compressor for ammonia used in a refrigeration apparatus using ammonia as a refrigerant.

  Today, there are many global environmental problems that require international efforts and immediate solutions. Among them, ozone layer destruction and global warming are related to refrigeration equipment. And there are international agreements on these issues, and R22 of HCFC refrigerant, which has been widely used before, is subject to regulation as destroying the ozone layer. HFC refrigerants such as R407C and R404A having a destruction coefficient of zero are replacing HCFC refrigerants. However, HFC refrigerants have a large global warming potential and are problematic in terms of preventing global warming, and they are prohibited from being released into the atmosphere together with HCFC refrigerants.

  Therefore, instead of these artificially created refrigerants, natural refrigerants that are natural substances and have properties as refrigerants have a zero ozone destruction coefficient, a low global warming coefficient, and exist in large quantities in nature. It has been reviewed from that. As this natural refrigerant, there is ammonia, which is corrosive, toxic, and flammable with respect to copper.

For this reason, in order to employ a screw compressor in a refrigeration apparatus using ammonia as a refrigerant, it is necessary to take measures against ammonia. Conventionally, there is a known example of a screw compressor for ammonia to which this measure has been taken (see, for example, Patent Document 1). .)
Japanese Patent Laid-Open No. 10-141226

  Patent Document 1 discloses a screw compressor for ammonia used in a refrigeration apparatus using ammonia as a refrigerant. The screw compressor for ammonia is an aluminum in which an aluminum enamel wire having ammonia resistance is adopted for a stator. Built-in motor.

In the case of an ammonia screw compressor that employs an aluminum-enamelled wire with ammonia resistance for the stator described above, the motor cost is significantly increased compared to other motors of the same specification, and the performance is poor. is there.
Incidentally, Patent Document 1 discloses a canned screw compressor using an open screw compressor and a canned motor in addition to the above compressor. In the case of this open screw compressor, the rotor shaft of the screw rotor on the drive side in the compressor body coupled to the output shaft of the motor passes through the compressor body casing via a mechanical seal. It is impossible to make zero, and there is a problem that leakage of ammonia from the inside of the compressor body cannot be avoided. Furthermore, since the mechanical seal has a durable life, there is a problem that maintenance of the mechanical seal is also required. On the other hand, in the case of a canned screw compressor, a canned motor in which the stator is isolated from the rotor by a can is used, which not only causes a significant increase in cost but also has a problem of poor performance.

  The present invention has been made with the object of eliminating such conventional problems, and eliminates the need for ammonia resistance measures in the motor stator, eliminates the risk of ammonia leaking out of the machine, and has good performance for ammonia. It is intended to provide a screw compressor.

  In order to solve the above-mentioned problem, the first aspect of the invention is that a compressor casing of a compressor body having a screw rotor on a driving side and a driven side that mesh with each other and a motor casing of a motor that is a driving unit are integrally coupled, In the ammonia screw compressor in a one-side support state in which the rotor shaft of the screw rotor on the driving side and the output shaft of the motor are directly connected and this output shaft is supported only on the rotor shaft side, The motor is positioned below, and these are arranged vertically, and the suction port of the compressor body is formed on the motor side, and a terminal portion for supplying power to the stator coil of the motor, and the stator coil The coil end was soaked in an oil having a specific gravity greater than that of the ammonia liquid and incompatible with the ammonia gas.

  In the second invention, in addition to the structure of the first invention, the oil surface in the motor is covered with a baffle plate made of an ammonia-resistant member and having a large number of small through-holes in the vertical direction.

  In addition to the configuration of the first invention, the third invention detects an oil supply passage for supplying the oil into the motor via an on-off valve, and detects the oil level in the motor, and the oil level is set. When the level is lower than the level, the on-off valve is opened, and an oil level sensor is provided that closes the on-off valve when the oil level reaches the set level.

  According to the ammonia screw compressor according to the first aspect of the present invention, the stator coil of the motor does not come into contact with the ammonia gas, so that it is not necessary to consider corrosion due to this, and a copper wire can be used. It is possible to make a semi-enclosed structure by integrating with the casing, zero leakage of ammonia gas to the outside of the machine, and coupled with the fact that copper wire can be used for the stator coil, the above terminal part is also general By using a conventional copper alloy, the production cost can be reduced.

  According to the ammonia screw compressor according to the second invention, in addition to the effects of the first invention, the baffle of the oil surface is suppressed by the baffle plate, and the coil end is always reliably immersed in the oil. As a result, the reliability of preventing corrosion of the stator coil using the copper wire can be further improved.

  According to the screw compressor for ammonia according to the third aspect of the invention, in addition to the effect of the first aspect, the oil level at the set level is maintained in the motor. There is an effect.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a refrigerating apparatus I using an ammonia refrigerant, to which the screw compressor 1A for ammonia according to the first invention is applied. The refrigeration apparatus I includes an oil screw compressor 1A, an oil separator / collector 2, a condenser 3, an expansion valve 4 and an evaporator 5, and a refrigerant circulation channel L1 including oil from the bottom of the oil separator / collector 2. An oil passage L2 that reaches the oil supply location in the ammonia screw compressor 1A through the cooler 6 is provided.

  The ammonia screw compressor 1A includes a compressor main body 13 having drive and driven screw rotors 11 and 12 meshing with each other, and a motor 14 serving as a drive unit. The compressor casing 15 and the motor of the compressor main body 13 are provided. 14 motor casings 16 are integrally coupled to form a semi-hermetic structure. The rotor shaft 17 of the screw rotor 11 on the driving side is directly connected to the output shaft 18 of the motor 14 and is in a one-side support state in which it is supported only on the rotor shaft 17 side. The compressor body 13 and the motor 14 are arranged vertically so that the motor 14 is positioned below the compressor body 13, and the suction port 21 of the compressor body 13 is on the motor 14 side, that is, the compressor body 13. It is formed below. That is, the suction port 21 of the compressor body 13 is provided below, and the discharge port 22 is provided above. Then, the ammonia gas sucked from the lower suction port 21 by the screw rotors 11 and 12 is compressed while receiving oil injection from the oil passage L2, and the compressed ammonia gas is accompanied by oil from the oil passage L2. The oil is discharged from the upper discharge port 22 toward the oil separator / collector 2.

  On the other hand, the rotor 23 of the motor 14 is suspended from the output shaft 18, and the stator coil of the stator 24 surrounding the rotor 23 is provided through the lower side surface of the motor casing 16 in a liquid-tight manner. Power is supplied from the terminal unit 25. The stator coil is made of copper wire, the terminal portion 25 is made of a commonly used copper alloy, and the coil end 26 and the terminal portion 25 of the stator coil are made of, for example, naphthenic mineral oil. As described above, the oil is immersed in an oil 27 having a specific gravity greater than that of the ammonia liquid and incompatible with the ammonia gas. As a result, the stator coil and the terminal portion 25 including the coil end 26 do not come into contact with the ammonia gas, and these are prevented from being corroded by the ammonia gas. Thus, the cost of the motor 14 is reduced by using a copper wire or a copper alloy. In addition, as described above, the compressor casing 15 and the motor casing 16 can form a semi-hermetic structure because the motor casing 16 is in communication with the compressor casing 15 in which ammonia gas flows. This is because the stator coil and the terminal portion 25 do not come into contact with ammonia gas. This semi-enclosed structure eliminates the leakage of ammonia gas to the outside of the machine. Further, it is not necessary to provide a partition wall such as a can for isolating the stator 24 from the space in the motor 14 including the rotor 23, and this does not cause a decrease in performance.

  The oil separator / recovery unit 2 has an oil separation element 31 therein, and an oil reservoir 32 communicating with the oil flow path L2 below the oil separator / collector 2, and is discharged into a space between the oil separation element 31 and the oil reservoir 32. Ammonia gas accompanied by oil from the outlet 22 is introduced. Then, the ammonia gas flows into the oil separation / recovery device 2, the oil is separated from the ammonia gas in the process of passing upward through the oil separation element 31, and the separated ammonia gas is located above the oil separation element 31. The separated oil is temporarily stored in the oil reservoir 32 and then exits from the oil flow path L2. The oil that has flowed into the oil flow path L2 is cooled by the oil cooler 6, and in addition to the rotor chamber in which the screw rotors 11 and 12 in the compressor body 13 are housed, the oil supply locations such as the bearing and the shaft seal portion After being guided, the oil is collected in the oil reservoir 32 through the discharge port 22 and repeatedly circulated.

  The ammonia gas that has flowed into the condenser 3 transfers heat to a low-temperature heat source, and condenses itself into ammonia liquid, which is squeezed and expanded in the process of passing through the expansion valve 4, enters a gas-liquid mixed state, and reaches the evaporator 5. Then, heat is received from the high-temperature heat source, and ammonia gas is returned to the compressor body 13 to repeat the same circulation as described above.

2 and 3 show a refrigerating apparatus II using an ammonia refrigerant to which the screw compressor 1B for ammonia according to the second invention is applied. In this refrigeration apparatus II, portions common to the above-described refrigeration apparatus I are denoted by the same reference numerals and description thereof is omitted.
In this refrigeration apparatus II, the oil level in the motor 14 is made of an ammonia-resistant member and is covered with a baffle plate 35 such as punching metal having a large number of small through portions 34 in the vertical direction.

  Such a configuration suppresses the ripples on the oil surface, makes it possible to maintain the state where the coil end 26 is always immersed in the oil 27 reliably, and is reliable in preventing corrosion of the stator coil using copper wire. It is possible to further improve the performance.

FIG. 4 shows a refrigerating apparatus III using an ammonia refrigerant to which the screw compressor 1C for ammonia according to the third invention is applied. In this refrigeration apparatus III, portions common to the above-described refrigeration apparatus I are denoted by the same reference numerals and description thereof is omitted.
In this refrigeration apparatus III, an oil supply passage L3 that branches from a portion of the oil passage L2 on the secondary side of the oil cooler 6 and replenishes the oil into the motor 14 via the on-off valve 37; When the oil level is detected and the oil level falls below the set level, the on-off valve 37 is opened, and when the oil level reaches the set level, the on-off valve 37 is closed. A surface sensor 38 is provided.

  With such a configuration, the oil level at the set level is maintained in the motor 14, and as a result, the coil end 26 is always immersed in the oil 27 reliably as in the case of the second invention described above. Thus, the reliability of corrosion prevention of the stator coil using the copper wire can be further increased.

  The above-described ammonia screw compressors 1A, 1B, and 1C are all provided with an oil-cooled compressor body 13, but the present invention is not limited to this, and the oil-cooled compressor. Instead of the machine main body 13, an oil-free compressor main body may be used. When this oil-free compressor main body is used, the oil separation / recovery unit 2 is omitted, and the discharge port 22 directly leads to the condenser 3. Further, in this case, for the ammonia screw compressor 1C according to the third invention, in the refrigeration apparatus III shown in FIG. 4, the oil supply source of the oil supply passage L3 is the oil reservoir 32, and the oil supply passage L3 is the oil supply portion. Instead of branching from the portion of the oil flow path L2 on the secondary side of the cooler 6, an oil supply source (not shown) may be separately provided, and the oil supply flow path L3 may be connected to this oil supply source.

It is a figure which shows the whole structure of the freezing apparatus to which the screw compressor for ammonia which concerns on 1st invention is applied. It is a figure which shows the whole structure of the freezing apparatus to which the screw compressor for ammonia which concerns on 2nd invention is applied. It is a top view which expands and shows the baffle plate in the motor shown in FIG. It is a figure which shows the whole structure of the freezing apparatus to which the screw compressor for ammonia which concerns on 3rd invention is applied.

Explanation of symbols

I, II, III Refrigeration apparatus 1A, 1B, 1C Screw compressor 2 for ammonia 2 Oil separator / recoverer 3 Condenser 4 Expansion valve 5 Evaporator 6 Oil cooler 11, 12 Screw rotor 13 Compressor body 14 Motor 15 Compressor casing 16 Motor casing 17 Rotor shaft 18 Output shaft 21 Suction port 22 Discharge port 23 Rotor 24 Stator 25 Terminal portion 26 Coil end 27 Oil 31 Oil separation element 32 Oil reservoir 34 Small through-hole 35 Baffle plate 37 On-off valve 38 Oil level sensor L1 Refrigerant circulation channel L2 Oil channel L3 Oil supply channel

Claims (3)

The compressor casing of the compressor body having the driving and driven screw rotors meshing with each other and the motor casing of the motor as the driving unit are integrally coupled, and the rotor shaft of the screw rotor on the driving side and the motor In the screw compressor for ammonia in which the output shaft is directly connected and this output shaft is supported only on the rotor shaft side in a one-side supported state,
The motor is positioned below the compressor body, and these are arranged vertically, and the suction port of the compressor body is formed on the motor side,
The terminal portion for supplying electric power to the stator coil of the motor and the coil end of the stator coil are immersed in oil having a specific gravity greater than that of the ammonia liquid and incompatible with the ammonia gas. Screw compressor for ammonia.   2. The screw compressor for ammonia according to claim 1, wherein the oil level in the motor is covered with a baffle plate made of an ammonia-resistant member and having a large number of small through portions in the vertical direction. An oil supply passage for replenishing the oil into the motor via an on-off valve and an oil level in the motor are detected. If the oil level falls below a set level, the on-off valve is opened. 2. The screw compressor for ammonia according to claim 1, further comprising an oil level sensor that closes the on-off valve when the oil level reaches the set level.

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