JP3348118B2 - Rotary compressor for ammonia refrigerant using canned motor and method of operating the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ammonia refrigerant compressor in which a canned motor is directly connected to, for example, a rotary compressor for ammonia refrigerant. In the event of leakage to the stator storage space side, while taking emergency measures to immediately stop the operation of the compressor,
The present invention relates to a structure of an ammonia refrigerant compression device capable of allowing a temporary continuous operation without impairing safety so as not to cause pollution by leaking the ammonia refrigerant to the outside air, and a method of operating the same.

[0002]

2. Description of the Related Art Conventionally, chlorofluorocarbon has been generally used as a refrigerant for a heat pump or a refrigeration cycle for cooling. However, chlorofluorocarbon has the property of being nonflammable, stable and extremely resistant to decomposition. When released into the atmosphere and accumulated, they destroy the ozone layer, thus limiting their use. Therefore, in recent years, ammonia refrigerants that have been practically used as alternatives to CFCs have been reviewed. Occurs. For this reason, the leakage of the refrigerant from the refrigeration cycle is extremely closely monitored, and as part of this, it is necessary to completely prevent the leakage of the compressed gas from the compressor, and it is directly connected to the compressor together with the compressor. A compression device in which the driving motor thus constructed has a sealed structure is being used. (Note: A sealed motor integrated with a compressor has never been used before.)

A motor used in such an ammonia refrigerant gas compressor includes a hermetic motor having a sealed structure in which the leakage of the ammonia refrigerant from a drive bearing portion on the compressor side is cut off from the atmosphere side on the motor side to form a hermetic structure. However, since the stator wire loop often cannot withstand the electrical insulation of the ammonia refrigerant in many cases, a thin metal cylindrical canister is inserted into a narrow gap between the stator core and the rotor. Using a canned motor, the stator side is hermetically cut off from the rotor side communicating with the compressor via bearings, and the stator wire loop provided on the stator core is Alternating magnetic flux is applied to the rotor through the can to rotate the rotor.

However, even if the stator housing space located on the outer peripheral side of the rotor housing space in the atmosphere of the ammonia refrigerant is sealed with a can, the temperature change occurring inside the motor or the can housing depending on the usage condition. The sealing function of the can may be deteriorated due to aging due to temperature fatigue of the O-ring of the sealing portion or the like, and in such a case, the ammonia refrigerant is supplied from the rotor storage space side to the stator storage space side. The space does not have a pressure-resistant structure against leakage and ammonia, and the stator wire loop or the like, which has no resistance, starts to corrode, and water that enters from outside air into the stator housing space. The corrosion may be promoted by the above, and the stator wire loop may be short-circuited or even broken.

[0005] In order to eliminate such a drawback, the present applicant has
The stator housing space, that is, the frame, side cover, etc. of the motor have a pressure-resistant structure, the stator wire loop, the connection connection portion connected to the wire loop, and a lead wire, a through terminal for further leading this lead wire out of the machine. For this purpose, various techniques have been proposed for performing corrosion resistance and insulation resistance treatment against ammonia refrigerant gas and for making the motor frame container with a pressure-resistant structure.

[0006]

However, if a crack having a pinhole is formed in the coating itself even after the corrosion and insulation treatment, the corrosion spreads from that portion and the stator wire is spread. Insulation failure such as a ring is likely to occur. In view of the drawbacks of the prior art, the present invention, even in the event that the sealing performance of the canister that hermetically cuts off the rotor housing space and the stator housing space in the atmosphere of the ammonia refrigerant is deteriorated, The stator storage space has a pressure-resistant structure so that no leakage of refrigerant occurs, and furthermore, while taking emergency measures to stop the operation of the compressor without immediately stopping the operation of the compressor,
An object of the present invention is to provide a structure of a rotary compressor for ammonia refrigerant and a method of operating the same, which enable continuous operation without impairing safety.

[0007]

The inventor of the present invention has made the stator housing space located on the outer peripheral side of the can have a pressure-tight and airtight structure against the outside world, and when the ammonia refrigerant leaks into this inside, the stator wire loop is formed. It has been found that the insulation resistance to enamel paints and other insulating paints is generally inversely proportional to the atmospheric pressure of ammonia, which is irreversible, reversible and in-between. (See FIG. 2) On the other hand, since the canned motor is integrally connected to the low pressure side of the compressor, the internal pressure of the can is maintained at the suction side of the compressor, in other words, almost at normal pressure. When the rotation of the compressor stops, the seal of the envelope between the rotor and the casing decreases, so that the pressure on the discharge side flows backward, and as a result, the pressure in the rotor storage space in the canned motor increases. It was found.

Therefore, when the pressure in the rotor housing space increases and the sealing performance of the can deteriorates, the pressure in the stator housing space side increases, and the insulation resistance of the stator wire loops and the like in the stator housing space increases. And deterioration of corrosion resistance is promoted. On the other hand, in a normal canned motor, the sealing performance of the can deteriorates, and when the ammonia refrigerant gas leaks to the stator housing space side, the refrigerant does not leak to the atmosphere side because the space does not have an airtight structure. And he was most hesitant to re-use it with ammonia refrigerant. However, in the conventional canned motor structure, the operation is continued in a state where the insulation resistance and the corrosion resistance of the stator wire and the like in the stator housing space are degraded, and the motor is short-circuited. It was in a state where it stopped only after it occurred. Therefore, in a normal canned motor, the sealing performance of the can deteriorates,
If there was leakage of ammonia gas on the stator storage space side, the operation was stopped immediately and the seal part of the can was repaired, but the leakage did not necessarily occur during the day, and air conditioning and other It is impossible to immediately stop the refrigeration cycle operation depending on the situation on the load side.

Therefore, the first feature of the present invention is that the stator space has a pressure-tight and airtight structure with respect to the outside air, and the refrigerant to the outside air is completely sealed. However, making the stator space a pressure-resistant airtight structure against the outside air means that when the rotation of the compressor stops, the pressure on the discharge side reversely flows and the sealing performance of the can deteriorates. The pressure increases, and the deterioration of insulation resistance and corrosion resistance of the stator wire loop and the like in the stator housing space is enhanced. Therefore, the second feature of the present invention is that an operation for removing the ammonia refrigerant pressure in the stator housing space is performed after the detection of the ammonia leak in the space. That is, specifically, when there is a request to stop the load operation on the rotary compressor side while continuing to operate even after detecting the ammonia leak in the stator housing space located on the outer peripheral side of the can. Without stopping the canned motor immediately, performing the operation for a predetermined time, reducing the ammonia pressure in the stator housing space to substantially normal pressure, and then stopping the rotation of the canned motor, and thereafter, It is for repairing.

In this case, making the stator housing space airtight with respect to the outside prevents the invasion of moisture and the like from the outside and further improves the corrosion resistance and insulation resistance. And, of course, the progress of the corrosion resistance and the insulation resistance is delayed by the operation, but since the ammonia is basically in a leaking state, the portion where the ammonia is in the stator housing space and the stator housing space and The member is preferably subjected to corrosion resistance and insulation resistance and ammonia resistance treatment. In this case, it is most necessary to use a material that is reversible with respect to other properties, such as insulation resistance, in the coating process, so that it can be placed in a primary ammonia refrigerant atmosphere. It will be recoverable. Also, the sensor for detecting the ammonia leak is as follows:
It is good to arrange in the stator storage space.

[0011]

According to the above technical means, even if ammonia refrigerant gas flows into the stator housing space due to deterioration of the sealing property of the can, the can compressor is immediately turned off when there is a request to stop the load operation on the rotary compressor side. In order to perform the no-load operation for a predetermined time without stopping the motor, the suction pressure of the ammonia pressure leaking to the canned motor side without lowering the sealing performance between the rotor and the casing on the compressor side. In other words, the stator wire loop in the stator housing space can be maintained in an atmosphere in which the deterioration of insulation resistance and corrosion resistance is not promoted. The continuous operation can be performed without promoting the deterioration of the insulation resistance, etc.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto, unless otherwise specified. It is only an example. First, FIG. 2 shows a relationship between an insulation resistance value of a stator coil and the like in an ammonia refrigerant gas atmosphere and a gas pressure.
Is a general insulation material and the curve B is A
3 shows characteristic curves of two kinds of materials when coated with polyethylene or the like. As can be understood from this figure, even if the insulation treatment is performed with an insulating agent having good contact resistance, in an ammonia refrigerant atmosphere, the electrical insulation deteriorates within a short time as the pressure increases. , B will not recover. In a coating such as A, which has reversibility, if a material having an insulating property within an allowable range that is not so affected by the gas pressure is selected, the insulation resistance is high in a low range of the refrigerant pressure, and the temporary operation is performed. It is possible to continue and during this time it is possible to eliminate the gas inside. As apparent from FIG. 2 above, polyethylene has a high resistance to ammonia, so that the insulation of the conductive part for covering or connecting the stator wire loop or lead-out wire wound on the stator and the lead-through terminal, which will be described later, Good for processing.

FIG. 1 is a partially cutaway cross-sectional view of a canned motor integrally connected to a fluid machine according to an embodiment of the present invention. Reference numeral 1 denotes an ammonia refrigerant gas compression directly driven to a canned motor 2. Of oil-cooled screw compressors and other rotary compressors for use with two intersecting bores (housings) having a high pressure port (discharge port 11) and a low pressure port (inlet port 12) and having parallel axes. A casing having a space, and a pair of male and female rotors disposed in the bore and engaged with each other and having a wrap angle of 360 ° or less, the compression ratio and the load / no-load operation control are controlled by slide control by a slide valve. Can do it. Such a configuration is well known.

On the other hand, the construction of the canned motor 2 directly connected to the compressor 1 will be described. A stator core 22 is fitted on an inner peripheral surface of a cylindrical outer shell frame 21 and the stator core 22 is fitted. The stator wire loop 23 wound around 22 has its wire end projected axially from both sides of the stator core 22.
The rotor 24 is opposed to the inner diameter of the stator core 22 via the can 25 with a small gap therebetween, and is disposed on both ends in the axial direction of the frame 21 via the rotating shaft 26 which is mounted at the center. The disk-shaped bracket 27 is rotatably supported by a bearing 28 fitted to a bearing support at the center of the disk-shaped bracket 27. Further, the rotating shaft 26 extends inside the compressor 1 and transmits torque to the rotors 13 and 14 of the compressor 1. The bearing 28 is forcibly lubricated with lubricating oil as is well known. A reinforcing cylinder 29 having a ring-shaped flange portion 29a is provided between the bracket 27 and the stator core 22 side on the bracket 27 side, respectively. The can 25 is fitted into a portion of the peripheral surface facing the rotor storage space 24A, and, if necessary, the outer peripheral side of the support portion of the bearing 28 is projected into a cylindrical shape slightly smaller in diameter than the inner diameter of the can 25, O in the axial direction
The rotor housing space 24A is sealed to the stator housing space 22A located on the outer peripheral side by interposing a ring. The stator housing space constituted by the frame 21 and the bracket 27 has a pressure-resistant sealing structure.

Reference numeral 32 denotes a refrigerant detection sensor for detecting ammonia gas that has entered the stator housing space 22A due to deterioration of the sealing performance of the can 25. The refrigerant detection sensor is disposed on the inner peripheral surface side of the outer frame 21 and has a signal detection lead. The wire can be led out to the outer peripheral side of the frame 21. Reference numeral 33 denotes a sealed-type through terminal for passing out a lead wire (not shown) from the wall of the outer shell frame 21 to the outside after connecting the stator wire loops 23 wound in, for example, three phases in a predetermined manner. The stator wire loop 23 and the lead wires each have an opportunity to come into contact with the ammonia refrigerant gas in the outer shell frame 21. Therefore, while using wires that are electrically insulated and coated with a polyethylene material, the connecting portions and After an insulating layer is formed on each of the insulating portion and the sealing portion of the through terminal 33, the surface thereof is covered with an ammonia-resistant layer made of a polyethylene material. Similarly, the stator wire loop 23 and the lead wires for the sensor 32 are also subjected to an electrical insulation treatment once for these electric wires and terminal portions, and then covered with an ammonia-resistant layer made of a polyethylene material.

Next, a description will be given of a method of operating the compressor when the refrigerant leaks into the stator housing space for the ammonia refrigerant in this embodiment. First, while the sealing ability of the can 25 is functioning smoothly, in other words, during normal operation, while the sensor does not detect leakage of ammonia in the stator storage space 22A side,
The operation of the canned motor is performed. When the sealing ability of the can 25 deteriorates and the ammonia refrigerant gas leaks to the stator housing space 22A side, the sensor immediately detects this and switches to the operation of discharging the refrigerant. That is, while detecting the ammonia leak in the stator housing space 22A, the operation is continued, the ammonia refrigerant is discharged, and the rotation of the canned motor is stopped after the end (STEP 5).

As a result, the stator housing space 22A does not cause a decrease in the insulation resistance of the stator wire ring 23 or the like due to the increase in the ammonia refrigerant gas pressure, does not exert any bearing on the stator wire ring, and has no Taking appropriate measures, even in the unlikely event that the can is damaged, it is possible to operate reliably without causing the refrigerant to leak to the outside air at all, so that the refrigerant leaks to the outside air at all and causes pollution, etc. Safety can be ensured without such a problem.

[0018]

As described above, according to the present invention, the rotor accommodating space and the stator accommodating space are configured to be pressure-resistant and airtight against emergency damage to the can under the environment of the ammonia refrigerant from the compressor side. Even if the sealing function of the can deteriorates, it is possible to take measures for the failure of the can without causing the refrigerant to leak to the outside air at all. Also, the motor can be prevented from being burned due to a short circuit of the stator wire loop or the like, by simply restoring only the can.

[Brief description of the drawings]

FIG. 1 is a partially broken sectional view of a canned motor of an ammonia refrigerant compression device according to an embodiment of the present invention. FIG.

FIG. 2 is a characteristic curve graph showing a relationship between an electric insulation resistance of a stator coil or the like in an ammonia refrigerant gas atmosphere and a gas pressure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Cand motor 23 Stator wire 24 Rotor 22 Stator iron core 25 Can 26 Rotation axis 12 Refrigerant detection sensor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F04B 39/00 F04B 49/10 F04C 29/10 H02K 3/44 H02K 5/128

Claims (3)

(57) [Claims] 1. A stator iron fixed to an inner peripheral side of an outer shell frame.
Rotor supported by bearings via a core and a rotating shaftAnd before
Between the stator iron coreMetal thin cylindrical key in a narrow space
Ammonia to the canned motorFor refrigerantcompression
Directly connected to the compressor, ammonia cold leaked from the compressor shaft seal
Ammonia-cooled so that the medium can be sealed in the rotor storage space
In medium rotary compressor,  The stator storage space located on the outer peripheral side of the can
Sealed structureAlong withInside the stator storage spaceSecond placePlace
To the electrical components to be treated with an ammonia-resistant treatment agent,
Further, an ammonia leak detection sensor is provided in the stator storage space.
SettingThen, the fixed by the ammonia leak detection sensor
If leakage of ammonia into the child storage space is detected,
After the discharge of the monya refrigerant, the rotation of the canned motor is started.
To stopAmmonia refrigerant characterized by the following
Rotary compression device. 2. The rotary compression device for an ammonia refrigerant according to claim 1, wherein said ammonia-resistant treatment agent is made of polyethylene or another reversible material . 3. A stator iron fixed to an inner peripheral side of an outer shell frame.
Rotor supported by bearings via a core and a rotating shaftAnd before
Between the stator iron coreMetal thin cylindrical key in a narrow space
Key to make the rotor storage space a hermetic structure
Directly connects a rotary compressor for ammonia to the
The leaked ammonia from the machine side is sealed in the rotor storage space.
Method of operating rotary compression device for ammonia that can be stopped
At,  In the stator storage space located on the outer peripheral side of the canArranged
Stator storage by leaked ammonia leak detection sensor
In spaceLeaks in waterWas detectedContinue after
While the load is running on the rotary compressor side.
When there is a stop request, immediately start the canned motor.
Predetermined to eliminate ammonia refrigerant pressure without stopping
Time operation, at least in the stator storage space
After reducing the ammonia pressure to almost normal pressure,
Rotation for ammonia, characterized by stopping the rotation of the motor
Operation method of rolling compression device.