JP2023160250A - fluid compressor - Google Patents

Abstract

To reduce pressure differential in an oil separator and also reduce pressure pulsation while maintaining an oil separating function without increasing the volume of a fluid compressor.SOLUTION: A fluid compressor 1 includes a scroll compression mechanism 4 provided in a housing 11, the scroll compression mechanism 4 being used for compressing refrigerant (fluid) and discharging it from a discharge port 20 to the outside of the housing 11. It further includes a centrifugal type oil separator 48 provided in the housing 11 for separating oil mixed into the refrigerant discharged from the scroll compression mechanism 4, and an expansion type external muffler 25 connected to the discharge port 20 of the housing 11.SELECTED DRAWING: Figure 1

Description

The present invention relates to a fluid compressor that compresses and discharges fluid using a compression mechanism provided in a housing, and particularly relates to a fluid compressor equipped with a centrifugal oil separator.

Conventionally, a fluid compressor has been configured to compress a fluid such as a refrigerant using a compression mechanism provided in a housing, and discharge the compressed fluid to the outside of the housing (to a discharge pipe connected to the discharge port) from a discharge port formed in the housing. ing. Furthermore, since the fluid discharged from the compression mechanism is mixed with lubricating oil, the discharge chamber of the housing is provided with an oil separator that separates the oil from the fluid using centrifugal force (for example, see Patent Document 1). ).

This centrifugal oil separator has a fluid inlet formed in the circumferential direction of the oil separator body, and the fluid containing oil that flows into the oil separator forms a swirling flow, and the centrifugal force at that time causes the oil to flow. Separated. The separated oil is recovered, and fluid discharge pulsation is also reduced due to the throttling effect of the oil separator and the damping effect of the discharge chamber that functions as a muffler within the housing.

Japanese Patent Application Publication No. 2007-192047 Japanese Patent Application Publication No. 2009-74485

Here, in such a centrifugal oil separator, a pressure difference is generated in the radial direction due to centrifugal force so as to balance the centrifugal force, and the inlet pressure of the oil separator is higher than the outlet pressure. Therefore, there is a problem in that the discharge pressure inside the compression mechanism becomes substantially high, the torque for compressing the fluid increases, and the total adiabatic efficiency (theoretical compression power/actual power) of the fluid compressor decreases.

In order to alleviate such a pressure difference inside the oil separator, it is effective to reduce the flow rate of the fluid flowing into the oil separator by increasing the flow path area of the inlet of the oil separator (Patent Document 1 mentioned above). reference). However, when the flow velocity of the fluid decreases, it becomes difficult to form a swirling flow inside the oil separator, and the oil separation function deteriorates. In addition, increasing the flow path area of the inlet of the oil separator will make it easier for pressure pulsations generated at the discharge valve provided at the position where fluid is discharged from the compression mechanism to propagate downstream, reducing the discharge pulsation at the fluid compressor outlet. (NVH: Deterioration of vibration noise).

In order to improve this worsened discharge pulsation, it is effective to increase the volume of the discharge chamber in the housing to improve the muffler function, but increasing the volume of the discharge chamber also increases the volume of the fluid compressor itself. A problem arises in which the constraints on connection and installation location cannot be satisfied. Note that some of this type of fluid compressors are provided with a muffler outside the housing (see, for example, Patent Document 2).

The present invention has been made to solve the conventional technical problems, and reduces the pressure difference and pressure pulsation in the oil separator while maintaining the oil separation function without increasing the volume of the fluid compressor. The purpose is to reduce the

In order to solve the above problems, a fluid compressor of the present invention includes a compression mechanism in a housing, and the compression mechanism compresses fluid and discharges it outside the housing from a discharge port. It is characterized by comprising a centrifugal oil separator that separates oil mixed in the fluid discharged from the compression mechanism from the fluid, and an expansion-type external muffler connected to the discharge port of the housing.

In the fluid compressor of the invention according to claim 2, in the above invention, the oil separator is provided with at least one pair of fluid inlets symmetrically with respect to the central axis, and the external muffler is on an extension of the central axis of the oil separator. It is characterized by its location.

In the fluid compressor of the invention according to claim 3, in the invention according to claim 1, the oil separator is installed in a discharge chamber configured in the housing, and between the fluid outlet of the oil separator and the inlet of the external muffler, A bypass flow path is formed that communicates the discharge chamber with the downstream side of the fluid outlet.

In the fluid compressor of the invention according to claim 4, in the above invention, the total volume of the discharge chamber and the external muffler is greater than or equal to 8 times the displacement volume of the compression mechanism plus or minus a predetermined error α, and less than or equal to 12 times plus or minus a predetermined error β. It is characterized by being set to .

The fluid compressor of the invention of claim 5 is characterized in that in the invention of claim 3, the total volume of the discharge chamber and the external muffler is set to 10 times the displacement volume of the compression mechanism plus or minus a predetermined error γ. shall be.

According to the present invention, in a fluid compressor which is provided with a compression mechanism in a housing and which compresses fluid by this compression mechanism and discharges it out of the housing from a discharge port, the fluid compressor is provided in the housing and the fluid discharged from the compression mechanism is Equipped with a centrifugal oil separator that separates mixed oil from the fluid, and an expansion-type external muffler connected to the discharge port of the housing, the oil separation function is maintained without increasing the volume of the fluid compressor. At the same time, it is possible to reduce pressure differences and pressure pulsations in the oil separator.

In this case, specifically, by providing at least one pair of fluid inlets symmetrically with respect to the central axis of the oil separator as in the second aspect of the invention, a swirling flow of fluid can be formed within the oil separator without any hindrance. At the same time, the pressure difference in the oil separator can be effectively reduced. Moreover, by arranging the external muffler on an extension of the central axis of the oil separator, pressure pulsations in the fluid can be effectively reduced.

Further, when the oil separator is installed in the discharge chamber formed in the housing as in the invention of claim 3, there is a gap between the fluid outlet of the oil separator and the inlet of the external muffler on the downstream side of the discharge chamber and the fluid outlet. By forming a bypass flow path communicating with the oil separator, the pressure at the inlet of the oil separator can be lowered. As a result, the discharge pressure of the compression mechanism is reduced, so the torque is reduced and efficiency can be improved.

Preferably, the total volume of the discharge chamber and the external muffler is set to 8 times plus or minus a predetermined error α or more and 12 times plus or minus a predetermined error β or less than the displacement volume of the compression mechanism. According to the invention of claim 5, by setting the total volume of the discharge chamber and the external muffler to 10 times the displacement volume of the compression mechanism plus or minus a predetermined error γ, the oil can be removed without increasing the volume of the fluid compressor. This makes it possible to effectively reduce pressure differences and pressure pulsations while maintaining the oil separation function of the separator.

1 is a schematic cross-sectional view of a fluid compressor according to an embodiment of the present invention. FIG. 2 is a plan cross-sectional view of an oil separator of the fluid compressor of FIG. 1;

Hereinafter, embodiments of the present invention will be described in detail based on the drawings. FIG. 1 is a schematic sectional view of a fluid compressor 1 according to an embodiment of the present invention, and FIG. 2 is a plan sectional view of an oil separator 48 thereof.

The fluid compressor 1 of the embodiment is used, for example, in a refrigerant circuit of an air conditioner for a vehicle, and sucks in refrigerant as the working fluid (fluid) of the air conditioner, compresses it, and discharges it to a discharge pipe. This is a so-called horizontal inverter-integrated scroll compressor that includes a motor 2, an inverter 3 for driving the electric motor 2, and a scroll compression mechanism 4 as a compression mechanism driven by the electric motor 2.

The fluid compressor 1 of the embodiment includes a stator housing 7 that houses an electric motor 2, an inverter 3, and a center casing 6 therein, a cover 8, and a rear casing 9. The stator housing 7, cover 8, and rear casing 9 are all made of metal (aluminum in the embodiment), and are integrally joined to form the housing 11 of the fluid compressor 1.

The stator housing 7 is provided with a partition wall 7A on one end side, and the partition wall 7A partitions the inside of the stator housing 7 into a motor chamber 12 that accommodates the electric motor 2 and an inverter housing section 13 that accommodates the inverter 3. . This inverter accommodating portion 13 has an open end surface, and this opening is closed by a cover 8 after the inverter 3 is accommodated. The other end of the motor chamber 12 is open, and after the electric motor 2 is housed in this opening, the center casing 6 is housed therein. Further, a sub-bearing 16 for rotatably supporting one end (front side) of the drive shaft 14 of the electric motor 2 is attached to the motor chamber 12 side of the partition wall 7A.

The center casing 6 is open on the side opposite to the electric motor 2 (the other end side), and this opening is used to accommodate a movable scroll 22 (described later) of the scroll compression mechanism 4, which will also be described later. The rear casing 9, to which the fixed scroll 21 is fixed, is fixed to the stator housing 7, thereby being closed.

The center casing 6 is provided with a through hole 17 through which the other end of the drive shaft 14 of the electric motor 2 is inserted. A main bearing 18 that rotatably supports the other end of the drive shaft 14 is attached to the mechanism 4 side.

The electric motor 2 includes a stator 22 having a coil wound thereon and fixed to the inside of the peripheral wall of the stator housing 7, and a rotor 23 rotating inside the stator 22. For example, direct current from a vehicle battery (not shown) is converted into three-phase alternating current by an inverter 3, and power is supplied to the coil of the stator 22 of the electric motor 2, so that the rotor 23 is rotationally driven. It is configured. The drive shaft 14 is fixed to this rotor 23.

Further, the stator housing 7 is formed with a suction port 21, and the refrigerant sucked from the suction port 21 passes through the electric motor 2 in the stator housing 7, flows into the center casing 6, and is compressed by the scroll. It is sucked into the suction part 37 outside the mechanism 4. Thereby, the electric motor 2 is cooled by the suction refrigerant. Further, the refrigerant compressed by the scroll compression mechanism 4 is discharged from a discharge port 20 formed in the rear casing 9 from a discharge chamber 27, which will be described later.

In the present invention, an expansion type external muffler 25 having a predetermined volume is attached to the discharge port 20, and a discharge pipe (not shown) is connected to this external muffler 25. The refrigerant flows from the discharge port 20 into the external muffler 25 outside the housing 11, and is discharged from the external muffler 25 to the aforementioned discharge pipe.

The scroll compression mechanism 4 includes the fixed scroll 21 and the movable scroll 22 described above. The fixed scroll 21 integrally includes a disk-shaped end plate 23 and a spiral wrap 24 formed of an involute shape or a curved line approximating the involute shape and set upright on the surface (one side) of the end plate 23. This wrap 24 is fixed to the rear casing 9 with the surface of the end plate 23 on which it is erected facing the center casing 6 side. A discharge hole 26 is formed in the center of the end plate 23 of the fixed scroll 21, and this discharge hole 26 communicates with a discharge chamber 27 in the rear casing 9. In the figure, 28 is a discharge valve provided at the opening of the discharge hole 26 on the back (other surface) side of the end plate 23.

The movable scroll 22 is a scroll that revolves around the fixed scroll 21, and includes a disk-shaped end plate 31 and an involute-shaped or similar involute structure erected on the surface (one side) of the end plate 31. It is integrally provided with a spiral wrap 32 made of a curved line and a boss 33 formed protrudingly from the center of the back surface (the other surface) of the end plate 31. The movable scroll 22 is arranged so that the protruding direction of the wrap 32 is on the fixed scroll 21 side, the wrap 32 faces the wrap 24 of the fixed scroll 21, and is arranged so as to face each other and engage with each other. form.

That is, the wrap 32 of the movable scroll 22 faces the wrap 24 of the fixed scroll 21, and is engaged with the wrap 32 such that the tip of the wrap 32 is in contact with the surface of the end plate 23 and the tip of the wrap 24 is in contact with the surface of the end plate 31, and is movable. The boss 33 of the scroll 22 is fitted with an eccentric portion 36 provided eccentrically from the shaft center at the other end of the drive shaft 14 . When the drive shaft 14 is rotated together with the rotor 23 of the electric motor 2, the movable scroll 22 is configured to revolve around the fixed scroll 21 without rotating.

Since the movable scroll 22 revolves eccentrically with respect to the fixed scroll 21, the eccentric direction and contact position of each wrap 24, 32 moves while rotating, and the pressure chamber 34 sucks refrigerant from the above-mentioned outside suction part 37. gradually shrinks as it moves inward. As a result, the refrigerant (fluid) is compressed and finally discharged from the central discharge hole 26 through the discharge valve 28 into the discharge chamber 27 .

In FIG. 1, 38 is an annular thrust plate. This thrust plate 38 is for partitioning a back pressure chamber 39 formed between the back surface of the end plate 31 of the movable scroll 22 and the center casing 6 and a suction section 37 outside the scroll compression mechanism 4. , located outside the boss 33 and interposed between the center casing 6 and the movable scroll 22. Further, 41 is a sealing material that is attached to the back surface of the end plate 31 of the movable scroll 22 and comes into contact with the thrust plate 38, and the back pressure chamber 39 and the suction section 37 are partitioned by this sealing material 41 and the thrust plate 38.

Further, 48 is an oil separator installed in the discharge chamber 27 of the rear casing 9 (housing 11). The oil separator 48 separates lubricating oil mixed into the refrigerant (fluid) discharged from the scroll compression mechanism 4 into the discharge chamber 27 from the refrigerant (fluid). The structure of this oil separator 48 will be described in detail later.

An oil storage chamber 44 is formed in the rear casing 9 below the oil separator 48 , and the oil separated from the refrigerant (fluid) by the oil separator 48 flows into this oil storage chamber 44 . In the figure, 43 is a back pressure passage formed from the rear casing 9 to the center casing 6. This back pressure passage 43 is a passage that communicates the oil separator 48 in the discharge chamber 27 (discharge side of the scroll compression mechanism 4) in the rear casing 9 with the back pressure chamber 39, and has an orifice 50 in the embodiment. There is. Thereby, the discharge pressure adjusted to be reduced by the orifice 50 of the back pressure passage 43 is supplied to the back pressure chamber 39 together with the oil in the oil storage chamber 44 separated by the oil separator 48.

This pressure (back pressure) within the back pressure chamber 39 generates a back pressure load that presses the movable scroll 22 against the fixed scroll 21 . Due to this back pressure load, the movable scroll 22 is pressed against the fixed scroll 21 against the compression reaction force from the pressure chamber 34 of the scroll compression mechanism 4, and the contact between the wraps 24, 32 and the end plates 31, 23 is maintained. The refrigerant can be compressed in the pressure chamber 34.

Next, the detailed structure of the oil separator 48 will be explained with reference to FIG. 2. The oil separator 48 of the embodiment includes an oil separation body 53 having a substantially cylindrical shape that is open upward and downward, and in which an oil separation space 52 is formed, and a collar 57 attached to the upper end of the oil separation body 53. This centrifugal oil separator is composed of a substantially cylindrical oil separation pipe 54 that is connected to the collar 57 from above and opens upward and downward.

In this case, the oil separation body 53 has an oil outlet 56 formed in its lower part, which communicates with the oil storage chamber 44, and a fluid outlet 55 formed in its upper part. Furthermore, a pair of inflow ports 58, 58 are provided at the upper side of the oil separation body 53 to introduce the refrigerant (fluid) in the tangential direction of the inner wall surface of the oil separation body 53 (FIG. 2). .

In this case, each inlet 58, 58 is formed at a point symmetrical position with respect to the central axis of the oil separator 48. Further, each inlet 58 in the embodiment is formed from two upper and lower through holes. Note that each inlet port 58, 58 may be configured not only by two through holes but also by one elongated hole that is vertically long. Further, in the embodiment, a pair of inflow ports 58, 58 are formed, but more pairs of inflow ports may be formed.

Further, in the embodiment, a bypass passage 61 is provided in the oil separation pipe 54 . This bypass passage 61 is composed of a small hole, and is located between the fluid outlet 55 of the oil separator 48 and the inlet of the external muffler 25, and is located between the discharge chamber 27 and the oil separation pipe 54 (on the downstream side of the fluid outlet 55). ) are in communication.

Further, the external muffler 25 is located on an extension of the central axis of the oil separator 48 (above the oil separator 48). Furthermore, the total volume of the external muffler 25 and the discharge chamber 27 is within a range of 8 times plus or minus error α (approximately 8 times) or more and 12 times plus or minus error β (approximately 12 times) or less than the displacement volume of the scroll compression mechanism 4. In this embodiment, the error is set to 10 times plus or minus error γ (approximately 10 times).

As mentioned above, the refrigerant (including oil) discharged from the discharge hole 26 of the fixed scroll 21 through the discharge valve 28 into the discharge chamber 27 flows from each inlet port 58, 58 to the oil separator 48 as shown by the arrow in FIG. The oil flows into the oil separation space 52. Note that the white arrows in FIG. 2 indicate the flow of refrigerant, and the black arrows indicate the flow of oil.

The refrigerant (fluid) that has flowed into the oil separation space 52 of the oil separator 48 swirls in the circumferential direction within the oil separation space 52 (arrows in FIG. 2), and due to the action of centrifugal force caused by the swirling, the refrigerant (fluid) has a large specific gravity (black arrow). ) comes into contact with the inner wall surface of the oil separation body 53 and is separated from the refrigerant (white arrow). The separated oil moves downward along the inner wall surface of the oil separation body 53, flows out from the oil outlet 56, and flows into the oil storage chamber 44.

On the other hand, the refrigerant (fluid) from which the oil has been separated flows out from the fluid outlet 55 of the oil separation body 53, flows into the oil separation pipe 54, rises as shown by the solid line arrow in FIG. leading to. The refrigerant discharged from the discharge port 20 then flows into an external muffler 25 located outside the housing 11, passes through the external muffler 25, and is finally discharged to the discharge pipe of the refrigerant circuit.

In this case, in the embodiment, since a pair of inflow ports 58 and 58 are provided point-symmetrically with respect to the central axis of the oil separator 48, the refrigerant containing oil that has flowed into the oil separation body 53 of the oil separator 48 is The flow rate is halved, and the centrifugal force is also halved. However, since the swirling flow of the refrigerant is maintained, the pressure difference between the inlet 58 and the fluid outlet 55 of the oil separator 48 can be reduced while maintaining the oil separation function.

Furthermore, in the embodiment, a bypass passage 61 is formed between the fluid outlet 55 of the oil separator 48 and the inlet of the external muffler 25, which communicates the discharge chamber 27 with the downstream side of the fluid outlet 55. The pressure at the inlet 58 of 48 can now be reduced. As a result, the discharge pressure of the scroll compression mechanism 4 is reduced, so the torque is reduced, and efficiency can be improved.

Here, as described above, since the movable scroll 22 revolves eccentrically with respect to the fixed scroll 21, pulsation occurs in the refrigerant (fluid) discharged from the discharge hole 26 to the discharge chamber 27 via the discharge valve 28. On the other hand, in the present invention, since the expansion type external muffler 25 is connected to the discharge port 20, the pulsation is absorbed and reduced in the space inside the external muffler 25. Further, since the external muffler 25 is arranged on an extension of the central axis of the oil separator 48, pressure pulsations of the refrigerant can be effectively reduced.

As a result, the pressure difference in the oil separator 48 can be reduced under various operating conditions such as the rotation speed and suction/discharge pressure of the fluid compressor 1 while maintaining the oil separation function without increasing the volume of the fluid compressor 1. This makes it possible to reduce the pressure pulsation and the pressure pulsation.

In particular, in the embodiment, the total volume of the discharge chamber 27 and the external muffler 25 is 8 times the displacement volume of the scroll compression mechanism 4 plus or minus a predetermined error α or more, and 12 times plus or minus a predetermined error β or less, in fact 10 Since it is set to double plus or minus a predetermined error γ, it is possible to reduce the pressure difference and pressure pulsation while maintaining the oil separation function in the oil separator 48 without excessively increasing the volume of the fluid compressor 1. will be able to be realized effectively.

In the examples, the present invention has been explained using a fluid compressor that compresses refrigerant as a fluid (working fluid), but the fluid is not limited to refrigerant, and the applicable system is also limited to vehicle air conditioners. It is not something that will be done. Further, in the embodiments, the present invention has been described using a scroll compressor equipped with a scroll compression mechanism, but the present invention is effective for fluid compressors equipped with various compression mechanisms such as a rotary type, a reciprocating type, and a swash plate type.

Further, in the embodiments, the present invention has been described using a so-called inverter-integrated fluid compressor, but it goes without saying that the present invention is not limited thereto and can be applied to a normal fluid compressor that does not have an integrated inverter.

1 Fluid compressor 4 Scroll compression mechanism (compression mechanism)
6 Center casing 7 Stator housing 9 Rear casing 11 Housing 20 Discharge port 21 Fixed scroll 22 Movable scroll 25 External muffler 27 Discharge chamber 44 Oil storage chamber 48 Oil separator 52 Oil separation space 53 Oil separation body 54 Oil separation pipe 55 Fluid outlet 58 Inflow port 61 Bypass flow path

Claims (5)

A fluid compressor that includes a compression mechanism in a housing, compresses fluid by the compression mechanism, and discharges the compressed fluid to the outside of the housing from a discharge port,
a centrifugal oil separator that is provided in the housing and separates oil mixed in the fluid discharged from the compression mechanism from the fluid;
A fluid compressor comprising an expansion type external muffler connected to a discharge port of the housing. The oil separator is provided with at least one pair of inflow ports for the fluid point-symmetrically with respect to a central axis,
The fluid compressor according to claim 1, wherein the external muffler is located on an extension of the central axis of the oil separator. The oil separator is installed in a discharge chamber configured in the housing,
2. A bypass flow path is formed between the fluid outlet of the oil separator and the inlet of the external muffler, the bypass flow path communicating between the discharge chamber and a downstream side of the fluid outlet. fluid compressor. The total volume of the discharge chamber and the external muffler is set to be greater than or equal to 8 times plus or minus a predetermined error α and less than or equal to 12 times plus or minus a predetermined error β of the displacement volume of the compression mechanism. The fluid machine according to item 3. 4. The fluid machine according to claim 3, wherein the total volume of the discharge chamber and the external muffler is set to 10 times the displacement volume of the compression mechanism plus or minus a predetermined error γ.

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