JP4126213B2 - Positive displacement compressor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a positive displacement compressor, and more particularly to a structure for reducing oil mist mixed in compressed gas.
[0002]
[Prior art]
A positive displacement compressor normally performs a compression operation by sucking gas into a closed space formed by a plurality of members and reducing the volume of the closed space by relative movement of these members. For this reason, the closed space requires a minute gap for enabling relative movement between the members forming the closed space, and is not strictly a sealed space. Since this minute gap causes leakage during compression, it is essential to take measures to improve the sealing performance at that location.
[0003]
An extremely effective and easy to implement means is the injection of oil into the gas during suction or during compression. Since the oil in the leakage flow seals the leakage gap with an oil film, the amount of leakage can be greatly reduced, and it is used in almost all positive displacement compressors other than oil-free machines. However, this means has a detrimental effect that a large amount of oil is mixed in the compressed gas to be discharged and the cleanliness of the compressed gas is impaired.
[0004]
As a conventional positive displacement compressor, compressed gas mixed with oil mist is discharged into the upper space of the compression section having a volume 10 times or more of the displacement volume, the flow rate of the compressed gas is lowered, and oil with a high specific gravity is compressed gas Then, the compressed gas is guided to the lower space of the compression section and discharged from the discharge pipe provided therein to the outside of the compressor (see, for example, Patent Document 1).
[0005]
[Patent Document 1]
JP-A-9-170570 (Example)
[0006]
[Problems to be solved by the invention]
In Patent Document 1, oil supplied to the bearing is injected into the suction chamber of the compression unit due to a pressure difference, and a large amount of oil is mixed in the compressed gas discharged into the upper space of the compression unit. In Patent Document 1, this oil can be separated in the upper space of the compression unit, but the oil that has adhered to the compression unit out of the separated and liquefied oil is returned to the oil storage chamber below the sealed container without being re-misted. Did not consider. For this reason, it traveled down from the side surface of the compression portion to the lower surface, and finally dropped onto a shaft or drive portion that moves at a high speed, thereby causing re-misting. As a result, the oil rate, which is the mass ratio of the oil to the total mass of the compressed gas mixed with the oil mist, does not decrease, and in the case of an air compressor, the compressed air is finally released to the atmosphere, which pollutes the environment. Produced. In the case of a compressor for refrigeration and air conditioning, there has been a problem that the refrigeration and air conditioning performance deteriorates due to a reduction in heat exchange efficiency due to adhesion to the inner wall of the heat transfer tube and an increase in pressure loss.
[0007]
An object of the present invention is to provide a positive displacement compressor with a reduced oil rate.
[0008]
[Means for Solving the Problems]
The object of the present invention is to
A motor having a rotating part and a fixed winding and stator ;
A frame disposed above the motor;
In a vertical scroll positive displacement compressor having
A cylindrical shield is disposed so as to be sandwiched between the frame and the motor,
The upper part of the cylindrical shield is fixed to the frame,
The lower part of the cylindrical shield is in contact with the winding,
In the vicinity of the lower end of the cylindrical shield, there is an oil return path through which oil flows from the winding,
This is achieved by a vertical scroll positive displacement compressor that is fixed to the upper portion of the stator and has a cylindrical oil ring that is fixedly disposed near the shaft of the motor rather than the shield.
[0013]
Next, the operation when means for solving the problem is used will be described. The oil separated from the compressed gas in the upper space of the compression section travels along the surface of the compression section by gravity and drops onto the rotating portion of the lower shaft and drive section (that is, the motor section) to re-mist. However, of the mist that scatters toward the discharge pipe adheres to the shield and does not reach the discharge pipe. And the attached oil reliquefies and the risk of re-scattering falls. This liquefied oil reaches the lower part of the shield along the shaft side surface of the shield by gravity. Since the lower part of the shield is in contact with the upper portion of the fixed portion of the drive unit forming the compression subordinate unit space, liquefied oil driver fixing portion upper partitioning the lower surface of the compression subordinate unit space without re misting To reach. Because the oil return passage to the vicinity of Oh, liquefied oil is returned to the oil reservoir before flowing to the drive unit rotating unit side. As a result, the amount of oil reaching the D pipe opening is extremely small, and the oil rate is greatly reduced.
[0016]
The driving unit for forming a compression subordinates portion space (i.e., the portion of the motor) part of the upper to the accumulated liquefied oil of the fixing unit is optimal because the upper oil return port of the shaft and the rotating part (rotor) Can be prevented from touching . That is , since it is possible to avoid mist formation again, there is an effect that the oil rate can be further reduced.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment when the present invention is applied to a scroll compressor will be described in detail with reference to FIGS.
[0018]
First, the configuration will be described. The fixed scroll member 1 engaged with the orbiting scroll member 2 is screwed to the frame 15 with the shaft 9 projecting downward to form the compression unit 200. At this time, the Oldham ring 5 is assembled between the frame 15 and the orbiting scroll member 2.
[0019]
A rotor 17a that is a rotating part of the motor 17 that is a driving part is fixed below the shaft 9 that protrudes from the compression part 200, and a winding that is a fixing part of the motor 17 and a stator 17b that are opposed to the rotor 17a on the outer peripheral surface thereof. Is arranged. The hermetic container 203 includes a motor 17 that is a drive unit connected to the compression unit 200 and the shaft 9. At this time, a compression unit upper space 204 having a volume about 30 times the displacement volume and a compression unit lower space 205 between the compression unit 200 and the motor 17 are provided above the compression unit 200.
[0020]
Here, since the discharge port 1a through which the compressed gas is discharged from the compression unit is located near the center of the upper surface of the fixed scroll member, the discharge port 1a faces the compression unit upper space 204. An oil storage chamber 210 for storing oil is provided at the bottom. Here, a plurality of flow grooves 201 are provided on the outer peripheral side of the compression unit 200 to link the compression unit upper space and the compression unit lower space.
[0021]
The stator 17b has a large number of axial winding holes 17d through which the windings 17c are passed. However, even after the winding, a space that passes through in the axial direction remains. It plays a role as an oil return path 206 returning to 210. Further, an oil return groove 207 which is a groove for oil return is also provided on the side surface of the stator.
[0022]
The suction pipe 18 that feeds gas into the compression unit passes through the sealed container 203 and is inserted into the suction space of the compression unit 200. The discharge pipe 19 is inserted into the compression unit lower space 205 through the inner D pipe port 19a.
[0023]
A cylindrical shield 208, which is a necessary component for one embodiment of the present invention, is screwed to the lower surface of the compression unit 200. As shown in FIG. 2, the cylindrical shield 208 is formed by screwing a metal shield base 208a and a plastic shield ring 208b whose reliability has been confirmed in the use environment in the compressor. Insulation is ensured so that there is no problem even if it contacts the windings of the stator. The lower end of the cylindrical shield 208 is disposed in contact with or very close to the upper part of the winding 17c that divides the lower side of the compression unit lower space. Thereby, both the lower circulation port 201a and the inner D pipe port 19a are arranged outside the cylindrical shield 208. An oil ring 209 is provided on the upper surface of the stator 17b on the inner side of the cylindrical shield 208, that is, on the shaft 9 side. The oil ring 209 is fixedly disposed by pushing or adhering a plurality of claws 209a protruding downward in the oil ring 209 shown in FIG. 3 into the upper oil return port 206a. The cylindrical shield 208 shields the inner D-pipe port 19 a connected to the discharge pipe 19 and the bearing portion of the frame 15 that supports the rotor 17 a and the shaft 4.
[0024]
Next, the operation will be described. The pressure in the back pressure chamber 16 which is the back space of the orbiting scroll member 2 is controlled to an intermediate pressure by the back pressure control valve 100 incorporated in the fixed scroll member 1. Since the discharge port 1a faces the sealed container, the inside of the sealed container becomes a discharge pressure. Due to these pressure differences, oil rises from the lower oil storage chamber 210 through the vertical hole 9a of the shaft, lubricates the bearing portion, and then enters the back pressure chamber 16.
[0025]
Therefore, after the Oldham ring 5 is lubricated, oil is injected into the suction chamber and the compression chamber formed between the scroll members through the back pressure control valve 100. Leakage in the gap between the suction chamber and the compression chamber is reduced, and the efficiency of the compressor is improved. Then, this oil becomes mist and is discharged from the discharge port 1a together with the compressed gas into the compression chamber upper space 204 having a large volume. Therefore, since the gas flow rate rapidly decreases, the oil mist carrying capability of the gas decreases rapidly, and oil having a large specific gravity adheres to the upper surface of the compression part due to gravity, and collects and liquefies.
[0026]
Since this liquefied oil has viscosity, it flows to the lower part along the surface of the compression part 200. When the liquefied oil reaches the cylindrical shield 208, most of the liquefied oil flows down the outer peripheral surface of the cylindrical shield 208 and reaches the upper surface of the stator 17b through the winding 17c that is in contact therewith. At this time, since the inner D pipe port 19a and the lower flow port 201a are both arranged outside the cylindrical shield 208, there is almost no gas flowing through the inner and outer spaces of the cylindrical shield 208. Therefore, even if the lower end of the cylindrical shield 208 is not in contact with the winding wire 17c, the oil flows smoothly and hardly re-mists. The oil ring 209 flows into the oil return path 206 without touching the rotor. For this reason, re-misting is avoided here.
[0027]
When a large amount of oil accumulates on the upper surface of the stator 17b and the oil return path 206 is insufficient, the oil returns to the lower oil storage chamber through the oil return groove 207 provided on the outer periphery. Therefore, in this embodiment, even when the winding 17c is dense and the cross-sectional area of the oil return path 206 is small, there is a specific effect that re-misting can be avoided.
[0028]
On the other hand, since the cylindrical shield 208 is fixed to the frame 15 with screws, a slight gap is formed between the frame and the cylindrical shield. A certain amount of oil flows into the gap and drops on the rotor 17 a and the shaft 9. This causes re-misting of the oil, but even in this case, the mist scattered in all directions by the cylindrical shield 208 adheres to the inner surface and is liquefied. And after that, it returns to the oil storage chamber 210, without re-misting similarly to the oil which flowed down the outer peripheral surface of the cylindrical shielding body 208. FIG. As a result, the oil mist mixed in the discharge pipe is extremely reduced, and a compressor having an extremely low oil rate can be provided.
[0029]
The fixed scroll member 1 shown in the embodiment of FIG. 1 has an asymmetric tooth profile in which the involute section on the fixed extension side extends to the suction side, as shown in FIG. For this reason, the compression chamber (referred to as the compression chamber A) formed on the inner line side of the fixed scroll spiral body 1b often has higher pressure than the compression chamber (referred to as the compression chamber B) formed on the outer line side. A large amount of gap leakage flows from the compression chamber A toward the compression chamber B. Therefore, if oil is mainly injected into the compression chamber A, leakage is reduced. For this reason, the back pressure control valve 100 in which the outflow groove 100a communicated with the inclined hole 100h shown in FIG.
[0030]
A detailed structure of the back pressure control valve 100 is shown in FIG. This is an enlarged view of a portion R in FIG. The back pressure control valve 100 includes a compressed valve spring 100b, a valve plate 100c, and a valve cap 100d. This is a valve that draws the gas and oil into the compression chamber A in order to lower the back pressure of the gas and oil that rises when the oil flowing into the back pressure chamber 16 and the fluid dissolved therein are gasified. .
[0031]
The back pressure is adjusted to a pressure obtained by adding a constant value corresponding to the compression amount of the valve spring 100b to the pressure at the opening end (compression chamber A) of the outflow groove 100a. As a result, there is a specific effect that the compression efficiency is improved and the performance becomes high.
[0032]
Further, in this method, the amount of oil injected into the compression chamber B side may be extremely reduced, which may cause a decrease in performance. In order to avoid this, the suction side of the end plate groove 1c (FIG. 5) is arranged on the side where the compression chamber B is closed. This end plate groove also serves to capture oil that leaks from the back pressure chamber 16 into the compression chamber, and since this oil can be concentrated and supplied to the compression chamber B, the extreme oil shortage in the compression chamber B can be alleviated, There is a unique effect of improving. Further, the end plate groove 1c has an effect of reducing sliding loss of the end plate portion and contributes to a reduction in input.
[0033]
Next, a second embodiment of the present invention will be described with reference to FIG. It is a downward perspective view of the cylindrical shield 208 which concerns on this invention. The shielding base 208a and the shielding ring 208b in FIGS. 1 and 2 are integrally formed of plastic which is an insulating material. Processing cost is reduced. Others are the same as those in the first embodiment, and other descriptions are omitted.
FIG. 7 shows another embodiment of the cylindrical shield according to the present invention. As shown in the lower perspective view of the lower part of the cylindrical shield 208, a cut is made in the lowermost part of the cylindrical shield 208 facing the upper part of the winding 17c to reduce the rigidity and somewhat interfere with the winding 17c. However, it is not damaged, and dimensional management becomes easy. Others are the same as those in the first and second embodiments, and other descriptions are omitted.
Moreover, according to the above Example, it is good also as following structures.
The positive displacement compressor has a compression unit that compresses a gas containing oil in a sealed container, a drive unit that includes a rotation unit and a fixed unit that are connected via a shaft protruding from a lower portion of the compression unit, and A discharge pipe for guiding the compressed gas in the sealed container to the outside, a discharge port for discharging the compressed gas from the compression part into the sealed container at the upper part of the compression part, and an oil storage chamber at the lower part in the sealed container; A compression unit upper space above the compression unit facing the discharge port, a compression unit lower space between the compression unit and the driving unit, a flow passage connecting the compression unit upper space and the compression unit lower space, and the compression unit lower space In the positive displacement compressor in which the oil return passage connecting the lower part of the oil storage chamber and the closed container side opening of the discharge pipe is provided in the lower space of the compression part, at least the shaft and the drive from the opening of the discharge pipe Rotating part May be provided, and a lower part of the shield may extend to an upper part of the fixed part of the drive unit, and an upper oil return port of the oil return path may be provided in the vicinity of the lower end of the shield. .
In addition, it has a compression section that compresses gas containing oil, a drive section that is connected via a shaft protruding from the lower part thereof, a sealed container that includes them, and a discharge pipe that guides the compressed gas in the sealed container to the outside. And a compression part that discharges compressed gas from the compression part into the sealed container at the upper part of the compression part and an upper part of the compression part that faces the oil storage chamber and the discharge port at the lower part of the sealed container, and a compression part of 10 times or more of the displacement volume The upper space, the compression portion lower space, the flow passage connecting the compression portion upper space and the compression portion lower space, the oil return passage connecting the lower portion of the compression portion lower space and the oil storage chamber, and the discharge pipe. In a positive displacement compressor in which an inner D pipe port, which is a closed container side opening, is provided in the lower space of the compression unit, a shield is provided so that at least the shaft and the rotating part of the drive unit cannot be seen from the inner D pipe port. body Lower is fixed to the upper compression subordinate unit space may be provided with a top oil return port is a compressed subordinate unit space end of Kaeaburaro near the lower end of the shield.
The operation when the above means is used will be described. The oil separated from the compressed gas in the upper space of the compression section travels along the surface of the compression section by gravity and drops onto the lower shaft and the rotation section of the drive section to re-mist. However, of the mist that scatters toward the discharge pipe adheres to the inner surface of the shield and does not reach the discharge pipe. And the attached oil reliquefies and the risk of re-scattering falls. This liquefied oil travels along the inner surface of the shield by gravity and reaches the lower part thereof. Since the lower part of the shield is connected to the upper part of the fixed part of the drive part that forms the lower part space of the compression part, the liquefied oil does not re-mist, and the upper part of the drive part fixed part that partitions the lower surface of the lower part of the compression part To reach. Since the oil return port is opened in the vicinity, the liquefied oil returns to the oil storage chamber before flowing to the drive unit rotating unit side. As a result, the amount of oil reaching the D pipe opening is extremely small, and the oil rate is greatly reduced.
Moreover, it is good also as what has a cylindrical shape surrounding a shaft and a drive part rotation part, and provided the lower distribution port which is a compression part lower space side edge part of a flow path in the outer space of this cylindrical shielding body. By using the above-mentioned means, the mist scattered in the direction different from the D pipe port also returns to the oil storage chamber as liquefied oil. Usually, since the inside of a closed container is complicated, the flow of compressed gas is also complicated. For this reason, even oil mist that has initially scattered from the shaft or rotating part in a direction different from the inner D-pipe port eventually reaches the inner D-pipe port. In addition, since both the inner D pipe port and the lower flow port are in the outer space of the shield, the liquefied oil is basically compressed at the location where the liquefied oil moves from the shield surface to the upper part of the drive unit fixing part that defines the lower surface of the lower part of the compression unit. There is no gas flow, making it more difficult to re-mist. From the above, the above means has an effect of further reducing the oil rate.
Moreover, it is good also as what formed the shielding body on the lower part of the compression part by pressing fixation arrangement | positioning, adhesion | attachment, or integrally forming.
By using the above means, the oil separated from the compressed gas in the upper space of the compression part reaches the lower part of the compression part by gravity, but the outer peripheral surface of the cylindrical shield is not dropped on the rotating part of the shaft or the drive part. It reaches to the upper part of the fixed part of the driving part that forms the lower space of the compression part. After this, it returns to the oil storage chamber through the oil return passage. That is, re-misting itself is avoided and the oil rate is reduced. For this reason, there is an effect that an even lower oil rate can be realized.
Moreover, it is good also as what fixedly arrange | positioned the cylindrical oil ring which surrounds a shaft on the upper surface of the fixing | fixed part of the drive part which forms compression part lower part space near a shaft rather than a shield.
By using the above means, a part of the accumulated liquefied oil on top of the fixed part of the drive unit forming the compression subordinate unit space is in contact with the upper oil return port optimum order, the shaft and the rotating part Can be prevented. That is , since it is possible to avoid mist formation again, there is an effect that the oil rate can be further reduced.
[0034]
【The invention's effect】
According to the present invention, there is an effect that a positive displacement compressor capable of reducing the oil rate can be realized.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a compressor in a first embodiment of the present invention.
FIG. 2 is a lower perspective view of the cylindrical shield in the first embodiment of the present invention.
FIG. 3 is an upper perspective view of the oil ring in the first embodiment of the present invention.
FIG. 4 is an enlarged longitudinal sectional view of a back pressure control valve in the first embodiment of the present invention.
FIG. 5 is a bottom view of the fixed scroll member in the first embodiment of the present invention.
FIG. 6 is a lower perspective view of a cylindrical shield according to a second embodiment of the present invention.
FIG. 7 is a lower perspective view of the lower end portion of the cylindrical shield in the third embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fixed scroll member, 2 ... Orbiting scroll member, 15 ... Frame, 17 ... Motor, 19 ... Discharge pipe, 100 ... Back pressure control valve, 200 ... Compression part, 201 ... Flow path, 204 ... Compression part upper space, 205 Compressor section lower space, 206, oil return path, 208, cylindrical shield, 209, oil ring, 210, oil storage chamber.

Claims (1)

A motor having a rotating part and a fixed winding and stator ;
A frame disposed above the motor;
In a vertical scroll positive displacement compressor having
A cylindrical shield is disposed so as to be sandwiched between the frame and the motor,
The upper part of the cylindrical shield is fixed to the frame,
The lower part of the cylindrical shield is in contact with the winding,
In the vicinity of the lower end of the cylindrical shield, there is an oil return path through which oil flows from the winding,
A vertical scroll type positive displacement compressor, wherein a cylindrical oil ring is fixedly disposed on an upper portion of the stator and is disposed closer to the shaft of the motor than the shield, and surrounds the shaft.

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