JPH0158354B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hermetic screw compressor mainly used for refrigerators.

FIG. 1 is a longitudinal sectional view of a conventional hermetic screw compressor. Both sides of the rotor casing 1 form a suction side end wall and a discharge side end wall, and are sealed by a suction casing 2 and a discharge casing 3, and a male rotor 4 and a female rotor 5 are engaged with each other. It is in contact with the bicircular arc shape outer periphery on the discharge side. When both rotors rotate in the direction of the arrow shown in the figure, the positions where they engage each other gradually move even though they have the same lead.The male rotor 4 and female rotor 5, which engage with each other by providing thread grooves and threads with large leads on their outer peripheries, The integrated shaft portions include journal bearings 6 and 7 (the journal bearing 7 is not visible in the figure) that are respectively fitted into the suction casing 2, and journal bearings 8 and 9 that are respectively fitted into the discharge casing 3 (the journal bearing 9 is not visible in the figure). The shaft of the male rotor 4 and the shaft of the female rotor 5 are fitted into the inner rings of the thrust bearings 12 and 13 fitted into the motor frame, and the shafts of the male rotor 4 and the female rotor 5 are fitted into the inner rings of the thrust bearings 12 and 13, which are fitted into the motor frame. Axial movement is restrained by nuts 14 and 15 screwed into (numerals 13 and 15 are not shown).

The integral shaft portion of the male rotor 4 is connected to a flexible drive shaft 17 via a shaft joint 16. Flexible drive shaft 17
The opposite end to which the shaft joint 16 is connected is connected to a hollow motor shaft 18 by a spline.

The two ends of the suction casing are covered by a cover 19 fixed to the suction casing 2.

The suction casing 2 is provided with a suction passage above, and a suction port 21 is opened at a position continuous with the upper end surface between the male rotor 4 and the female rotor 5. Suction port 2
A discharge port is provided on the end face of the discharge casing 3 on the opposite side of the position where the male rotor 4 and the female rotor 5 meet each other below the rotor 1 (not shown in the figure).

A cylinder 11 is fixed to the suction casing 2 and its cover 19.

An unloader piston 23 sealed by a sealing ring is fitted into the cylinder 11, and the piston rod is sealed in a hole in the suction casing 2 and extends into the rotor casing 1, changing the suction side volume to change the suction amount. Slide valve 24 to adjust
is fixed. Reference numeral 20 designates a balance piston that is rotatably fitted into the shaft of the male rotor 4, has an outer diameter side that is closely connected to the cylinder chamber 20a, and balances the thrust with the male rotor 4 by applying pressure oil to the cylinder chamber 20a. .

A motor frame 25 is fixed to the discharge casing 3 , and an oil separation casing 27 is fixed to the motor frame 25 via a bearing plate 26 .

A stator 29 is fixed within the motor frame 25, and a rotor 33 is fixed to a motor shaft 18 that is supported by a bearing 32 that fits into a partition wall 31 and a bearing plate 26 of the motor frame 25. Partition wall 31
The bearing plate 26 is provided with openings 31a and 26a. An oil separator 34 is provided in the oil separation casing 27, and the oil separation casing 27 is provided with a delivery 35 and an oil outlet 36 for separating oil.

As is clear from the above, the screw compressor, motor, and oil separator are lined up in this order from the left in the figure and are integrally connected.

When the motor is energized, the motor shaft 18 rotates,
The flexible drive shaft 17 rotates.
When the male rotor 4 is rotated via the shaft joint 16, the female rotor 5 that engages therewith rotates in the opposite direction to the male rotor 4. These rotation speeds are rotated at high speed by an electric motor with a synchronous speed of about 3000 rpm, as an example.

When the male rotor 4 and the female rotor 5 rotate, gas is sucked into the suction space formed by the rotor casing 1, the male rotor 4, and the female rotor 5 from the suction port 21 through the piping (not shown), and the gas is sucked into the male rotor from the compression space part. 4. The outer periphery of each of the female rotors 5 is in close contact with the inner periphery of the casing 1, and one pitch of these rotors becomes a compression space from the discharge side,
The gas is gradually compressed as the volume between the male rotor 4, female rotor 5 and casing 1 decreases, and is discharged to the discharge port, exits into the space between the discharge casing 3 and the partition wall 31 of the motor frame, passes through the opening 31a, and enters the motor. to go into. Then, from the left side to the right side of the figure, it passes through the space between the stator 29 and the rotor 33 and the passage provided between the stator 29 and the motor frame 25, passes through the opening 26a of the bearing plate 26, and enters the oil separation casing 27. The refrigerant mixed with the oil supplied to the screw compressor is transferred to the oil separator 34.
The refrigerant is separated into refrigerant and oil by the delivery 35
It is then sent to the next stage of the refrigeration cycle.
The separated oil is collected at an oil outlet 36 and collected in an oil tank (not shown), cooled by a cooler, and sent to a screw compressor by an oil pump.

The above-mentioned conventional compressor of this type was constructed as shown in FIG. 1 and had the following drawbacks.

1. Because it is horizontal, it is long in the axial direction and requires a large installation space.

2. Because the drive motor is located on the discharge side of the screw compressor, it is in an atmosphere of a mixture of refrigerant and a large amount of oil, and this mixture is at a high temperature of 60℃ to 100℃, so a structural design that increases the cooling effect is required. be lost. Due to the large amount of oil and refrigerant contained in the discharged gas, the motor coil is susceptible to poor insulation, ie, softening, swelling, and melting due to heat, resulting in a shortened lifespan.

3 Since the compressor rotor casing is single layer,
Rotor meshing noise and rolling bearing noise are loud.

4 A separate oil tank is required to store the separated oil.

In contrast, the screw compressor shown in Japanese Utility Model Application Publication No. 57-145790 places the drive motor on the suction side of the compressor, which solves the problem regarding the temperature of the motor, but requires a large installation space and requires a separate There are disadvantages such as the need for an oil tank.

SUMMARY OF THE INVENTION An object of the present invention is to provide a hermetic screw compressor that is small in size, requires a small installation space, does not heat up the motor, operates quietly, and does not require a separate oil tank.

The present invention comprises an oil separation element for oil contained in a refrigerant and an oil reservoir for separated oil, and two parts are provided in a casing in parallel and overlapping each other such that the distance between their axes is smaller than the diameter of the casing. A male rotor and a female rotor are each rotatably supported around the bore center and mesh with each other in a cylindrical bore, and the casing has a suction side end perpendicular to the bore axis at both ends of the bore. The suction side end wall and the discharge side end wall have an end wall suction port and an end wall discharge port, respectively, and bearings for supporting the shafts of the male and female rotors are provided on the suction side and the discharge side. The drive shaft of the screw compressor and the shaft of the fully enclosed motor are vertically arranged and directly connected, and the inside of the motor is kept under low pressure so that the working fluid is sucked into the screw compressor through the inside of the motor. In a closed screw compressor in which a screw compressor and a motor frame are connected, at least the screw compressor is sealed with an outer casing spaced apart from the casing of the screw compressor, and the inside of the outer casing is a high pressure chamber. A compressed working fluid delivery is arranged in the upper part of the outer casing, and an oil separation element is arranged between the discharge port of the screw compressor and the delivery of the outer casing so as to block the space between the outer casing and the outer periphery of the screw compressor. It is characterized by being equipped with a hermetic screw compressor that uses the lower space of the outer casing as an oil reservoir.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a longitudinal sectional view, and FIG. 3 is a longitudinal sectional view perpendicular to FIG.

The rotor casing, motor frame, and suction casing are integrated into a casing 10, with journal bearings 6, 7 fitted into the rotor casing part 1a and journal bearings 8, 9 fitted into the discharge casing 3 fixed to the rotor casing part 1a.
This supports an integral shaft portion of a male rotor 4 and a female rotor 5, each of which has screw threads that engage with each other on its outer periphery. On the sides of the journal bearings 8 and 9, thrust bearings are provided on the discharge casing 3 and a cover 37 fixed to the discharge casing 3 so as to engage with the shafts of the male rotor 4 and female rotor 5 to carry the thrust of both rotors 4 and 5. Bearings 12 and 13 are provided, and a male rotor 4,
These rotor shaft ends are locked so as to carry the thrust of the female rotor 5.

Rotor casing part 1a and motor frame part 2
A suction port 21 of the screw compressor is opened in the partition wall between the compressor 5a and the compressor 5a. Rotor casing part 1a
An outer casing 38 is spaced apart from the outer periphery and fixed in sealing contact with a flange 39 at the boundary between the motor frame section 25a and the rotor casing section 1a, so that the rotor casing section 1a is completely covered. A discharge port 22 is provided in the discharge casing 3, and a delivery 35 is provided in the outer casing 38 with a demister 41 disposed between the rotor casing portion 1a and the outer casing 38.

The lower part of the outer casing 38 serves as an oil reservoir 46, which communicates with the oil outlet 36 through an oil filter 42. Inner periphery of motor frame portion 25a and stator 2
9, passages 25b are provided at multiple locations in the motor axial direction. Motor frame part 25 of the casing
A motor cover 43 fixed to a has a refrigerant intake port 44.

The motor shaft 30 is the male rotor 4 of the screw compressor.
Only one side of the rotor 33 is supported by journal bearings 6 and 8.

Although not shown, journal bearings 6, 7, 8,
9. Thrust bearings 12 and 13, the meshing part of the male rotor 4 and the female rotor 5, the sealing part between the outer periphery of the male rotor 4 and the female rotor 5 and the inner periphery of the rotor casing part 2a, the male rotor 4 and the female rotor 5, Oil is fed into the working space where the compression action is performed for the purposes of cooling, lubrication, sealing, etc., and these oils are eventually discharged from the screw compressor together with the refrigerant.

When the motor is energized, the motor shaft 30 rotates,
The male rotor 4 rotates and the female rotor 5 rotates in the opposite direction to the male rotor 4. The refrigerant sucked in from the refrigerant intake port 44 enters the motor cover 43, passes through the space between the stator 29 and the rotor 33, the passage 25b between the motor frame portion 25a and the stator 29, and enters the motor lower space 45. Therefore, the stator 29 and the rotor 33 are cooled by low-temperature refrigerant gas from the surroundings. The refrigerant is sucked into the screw compressor from the lower space 45 through the suction port 21, and the space following the meshing portions of the male rotor 4 and female rotor 5 moves to the discharge side, where the refrigerant gas is compressed and transferred to the discharge casing 3. Outer casing 3 from discharge port 22
8, pass through the demister 41, and pass through the demister 41.
As a result, the oil in the refrigerant supplied to the screw compressor is separated and falls into the oil sump 46 in the lower part of the outer casing 38. The oil in the oil reservoir 46 is removed by the oil filter 4
2, the oil is sucked out from an oil outlet 36 by an oil pump (not shown), cooled by an oil cooler (not shown), and sent to a screw compressor.

The oil-free refrigerant gas that has passed through the demister 41 is circulated from the delivery 35 to the refrigerant intake port 44 of the motor cover 43 through a necessary process in the refrigeration cycle. In the screw compressor, the thrust of the male rotor 4 is the male rotor 4, the motor rotor 33,
It works upward against the gravity of the motor shaft 30 and the like, and is supported by the thrust bearing 12.

FIG. 4 shows another embodiment of the invention. The first embodiment has a motor in the upper part and a screw compressor in the lower part, but this embodiment has a motor in the lower part and a screw compressor in the upper part.

Rotor casing part 1a and motor frame part 2
The casing 10 with which the casing 5a is integrated is fixed to the base 47. The structure inside the motor frame portion 25a is the same as the first embodiment turned upside down. Refrigerant intake port 4
4 is provided so that the space between the base 47 of the motor frame portion 25a, the stator 29, and the rotor 33 communicates with the outside.

The configuration of the screw compressor is the same as in the first embodiment. The outer casing 38 is fixed to a flange 39 of the casing 10. The demister 41 is provided to partition the outer casing 38 between the screw compressor and the delivery 35 provided at the top of the outer casing 38.

When the motor is energized, the screw compressor rotates, and the refrigerant entering from the refrigerant intake port 44 flows into the stator 2.
9. The oil passes through the space between the rotors 33 and the passage 25b, passes through the space 45, is sucked into the screw compressor from the suction port 21, is compressed, enters the outer casing 38 from the discharge port 22, and is separated by the demister 41. The refrigerant is supplied from the delivery 35 to the refrigeration cycle, and the oil accumulates in the oil sump 46 and passes through the oil filter 4.
2 and is taken out from the oil outlet 36. Still other embodiments may be horizontal. That is, it is placed horizontally in the state shown in Fig. 2, Fig. 3, or Fig. 4,
A delivery is provided in the upper part of the outer casing, the inside of the outer casing is partitioned with a demister between the delivery and the discharge port of the screw compressor, and an oil filter and an oil outlet are provided in the lower part of the outer casing as an oil reservoir.

The effects of the present invention are as described above: (1) Because of the vertical arrangement, the installation space is small, so multiple units can be installed in parallel. Since the weight of the compressor rotor and the rotor of the drive motor in the radial direction is eliminated, the bearing load is reduced. Furthermore, since the shaft does not deflect due to its own weight, a cantilevered drive motor is sufficient. Cantilevering simplifies the oil supply system and reduces bearing noise due to fewer bearings. In the thrust direction, the rotor's own weight is applied when the rotor is stopped, but when the rotor is in operation, a thrust force acts in the direction opposite to its own weight, so the thrust load is reduced by the amount of the rotor's own weight, so the thrust bearing may be small. By arranging the discharge port of the discharged gas at a position lower than the oil separation element, the effect of separating a large amount of oil in the discharged gas by gravity can also be expected. Part of the oil contained in the suction port gas and the oil leaked from the suction side seal are introduced into the compression chamber without retention.

(2) Since the demister is placed between the outer periphery of the screw compressor and the outer casing, increasing the length of the machine due to the installation of the demister is avoided, and the overall length of the device is shortened. Furthermore, since the area of the oil reservoir is large, it can be made shallow, which also contributes to shortening the overall length of the device, allowing the device to be made smaller.

(3) In this embodiment, the drive motor is placed on the low-pressure side of the screw compressor, and the refrigerant gas intake is provided on the opposite side of the screw compressor, so the drive motor is cooled with low-temperature suction gas during operation. Since the cooling effect is high and the suction gas temperature is almost constant, stable operation can be continued. And the motor can be made smaller. Since the suction gas contains almost no oil, deterioration in insulation due to oil and refrigerant can be prevented.

(4) In the embodiment, the low-pressure chamber and the high-pressure chamber are divided into two by the partition wall, and the suction gas is not heated by the high-temperature discharged gas, so that a decrease in volumetric efficiency can be suppressed.

(5) In the embodiment, the high pressure chamber has a double casing, which has the effect of reducing rotor meshing noise and rolling bearing noise. And since no shaft seal is required, there is no refrigerant leakage. The outer casing is just a casing and is completely sealed. The compressor drive motor, oil separation device and oil reservoir unique to screw compressors are all integrated, making it smaller and lighter.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a conventional example, FIG. 2 is a longitudinal sectional view of an embodiment of the present invention, and FIG. 3 is a longitudinal sectional view taken in a direction perpendicular to FIG. DESCRIPTION OF SYMBOLS 1... Rotor casing, 1a... Rotor casing part, 2... Suction casing, 2a... Rotor casing part, 3... Discharge casing, 4...
Male rotor, 5... Female rotor, 6, 7, 8, 9...
Journal bearing, 10...Casing, 11...
Cylinder, 12, 13... Thrust bearing, 14,
15... Nut, 16... Shaft coupling, 17... Flexible drive shaft, 18... Motor shaft,
19...Cover, 20...Balance piston, 2
0a...Cylinder chamber, 21...Suction port, 22...
Discharge port, 23... Unloader piston, 24...
Slide valve, 25...Motor frame, 25
a...Motor frame part, 25b...Passway, 26
... Bearing plate, 26a ... Opening, 27 ... Oil separation casing, 29 ... Stator, 30 ... Motor shaft, 31 ... Partition wall, 31a ... Opening, 32 ... Bearing, 33 ... Rotor, 34 ... ...Oil separator, 35...Delivery, 36...Oil outlet, 37...
... Cover, 38 ... Outer casing, 39 ... Flange, 41 ... Demister, 42 ... Oil filter, 43
... Motor cover, 44 ... Intake port, 45 ... Lower space, 46 ... Oil sump, 47 ... Base.

Claims (1)

[Scope of Claims] 1. An oil separating element for oil contained in a refrigerant and an oil reservoir for separated oil, which are arranged parallel to each other in a casing and overlapped with each other such that the distance between the shafts is not less than the diameter of the casing. Two cylindrical bores each include a male rotor and a female rotor that are rotatably supported around the bore center and mesh with each other, and the casing has a rotor at both ends of the bore perpendicular to the bore axis. The suction side end wall and the discharge side end wall each include an end wall suction port and an end wall discharge port, and bearings for supporting the shafts of the male and female rotors. The drive shaft of the screw compressor and the shaft of the fully enclosed motor are arranged vertically and directly connected, so that the working fluid is sucked into the screw compressor through the inside of the motor. In a hermetically sealed screw compressor in which the inside of the motor is a low pressure chamber and the screw compressor and motor frame are connected, at least the screw compressor is hermetically covered with an outer casing spaced apart from the casing of the screw compressor, The inside of the outer casing is a high pressure chamber, the delivery of compressed working fluid is arranged on the upper part of the outer casing, and an oil separation element is installed between the discharge port of the screw compressor and the outer casing so as to close the space between the outer casing and the outer periphery of the screw compressor. This is a hermetic screw compressor that is placed between the delivery areas and uses the space below the outer casing as the oil reservoir. 2. The hermetic screw compressor according to claim 1, characterized in that the high pressure chamber is arranged in the upper part and the low pressure chamber is arranged in the lower part. 3. The hermetic screw compressor according to claim 1, wherein the low pressure chamber is arranged in the upper part and the high pressure chamber is arranged in the lower part. 4. Any one of claims 1 to 3, wherein the bearings that support the shafts of the male and female rotors of the screw compressor on the discharge side are provided with a thrust bearing in parallel with a radial bearing. The hermetic screw compressor described in .