JP4868901B2 - Hermetic electric compressor and refrigeration cycle apparatus - Google Patents

Description

  The present invention relates to a hermetic electric compressor that is used, for example, for refrigerant compression of air-conditioning / refrigeration equipment, and a refrigeration cycle apparatus that uses this hermetic electric compressor.

  In this type of hermetic electric compressor, a plate-like oil separator is held near the upper end of the rotor, and at the same time, the arrangement of the discharge gas flow path in the hermetic container is devised, so that gas and lubricating oil are contained in the hermetic container. The ratio of the lubricating oil contained in the discharge gas (oil circulation rate) is suppressed.

Conventionally, as a method of holding an oil separator, a configuration in which an oil separation plate is fixed by rivet caulking to a rotor via a spacer (Patent Documents 1 and 2), and a fixed-use member such as a C-shaped retaining ring is provided on a drive shaft. A configuration (Patent Document 3) that is fixed by using, a configuration (Patent Document 3) in which a claw-shaped spring portion is integrally provided on an oil separation plate and engaged with a drive shaft are known.
Further, regarding the flow path of the discharge gas, a mode in which a gas flow path is provided in the drive shaft (Patent Document 4), a mode in which the flow path area in the stator is secured to a certain level (Patent Document 1), the inner peripheral side of the stator There is known a configuration (Patent Document 5) in which a predetermined difference is provided in the flow path resistance on the outer peripheral side.

JP 2001-12374 A (FIG. 4, claims 7 and 8) JP-A-8-28476 (FIG. 2) JP-A-5-332276 (FIGS. 3 and 4) Japanese Patent Laid-Open No. 4-325795 (FIG. 1) Japanese Patent No. 3420641 (Claim 1)

Conventionally, this type of electric hermetic compressor generally has the following problems with respect to oil separation.
(A) The number of parts required to fix the oil separator increases.
(A) If the gas flow path area in the sealed container is expanded and the gas flow rate is lowered to prevent the lubricating oil from rolling up, the motor core volume decreases, the motor efficiency decreases, and the performance deteriorates.
(C) In the form in which the oil separation plate is caulked and fixed to the rotor via the spacer, it is difficult to widen the gas flow path hole in the rotor.
(D) In the embodiment in which the claw-shaped spring portion is engaged with the drive shaft, a gap communicating between the upper and lower surfaces of the oil separation plate remains, and the oil separation function is deteriorated.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to obtain a compressor having a low oil circulation rate without increasing the number of parts or reducing the performance.

A hermetic electric compressor according to the present invention includes a hermetic container having a discharge port above a predetermined position, a stator provided in the hermetic container, a motor disposed on the inner side of the stator, and a hermetic container. A compression mechanism portion that is provided below the motor and is driven by a drive shaft that is inserted into the rotor, and a lubricating oil that lubricates the compression mechanism portion is sealed in the bottom of the hermetic container, and at least the upper and lower ends of the rotor of the motor are A gas flow path comprising a plurality of through-holes communicating in the axial direction, and a substantially disk-shaped oil separation plate that is held at a predetermined interval from the upper end of the gas flow path portion and rotates together with the rotor. In the hermetically sealed electric compressor, the oil separation plate includes a disc portion and a cylindrical wall that is erected at a right angle to the disc portion and has a hollow hole formed in the center of rotation. inner wall fitting tightens the drive shaft It is fitted interpolated held by, the motor, the first gas flow path including the total cross-sectional area A ₁ comprising a plurality of through holes communicating the upper and lower ends of the rotor in the axial direction, the rotor outer peripheral surface and the stator inner peripheral surface A _second gas flow path having a total cross-sectional area A ₂ composed of an air gap secured between the opening and the opening of the winding accommodating slot in the stator and an inner peripheral surface of the stator, and a winding of the stator Is formed on the outer peripheral side from the inner wall of the sealed container and includes a plurality of through-holes communicating with the upper and lower ends of the motor in the axial direction, and has a total cross-sectional area A ₃ smaller than either A ₁ or A ₂ . A gas flow path is formed .

The hermetic electric compressor according to the present invention has a gas flow path formed of a plurality of through holes that communicate axially at both upper and lower ends in at least the rotor, and is held at a predetermined interval from the upper end of the gas flow path portion. In a hermetic electric compressor comprising a substantially disk-shaped oil separator that rotates together with the oil separator , the oil separator is erected at a right angle to the disc and the disc hole. A cylindrical wall formed in the center, and the inside of the cylindrical wall is held by being fitted with a drive shaft with an interference fit, and the motor has a plurality of through holes that communicate the upper and lower ends of the rotor in the axial direction. A _first gas flow path having a total cross-sectional area A _1, an air gap secured between the outer peripheral surface of the rotor and the inner peripheral surface of the stator, and the opening of the winding accommodating slot in the stator to the inner peripheral surface of the stator. A _second gas having a total cross-sectional area A ₂ comprising a groove portion The passage is composed of a plurality of through-holes that are formed on the outer peripheral side of the stator winding and on the inner side of the inner wall of the sealed container and communicate with the upper and lower ends of the motor in the axial direction, and are smaller than either A ₁ or A _2. Since the third gas flow path having the total cross-sectional area A ₃ is formed , the discharge gas from the through hole toward the discharge port is once blocked by the oil separation plate and given a rotational motion. Thereby, the lubricating oil mixed in the discharge gas is separated by the centrifugal force due to the difference in specific gravity, and has the first effect of preventing the oil from flowing out of the closed container at the upper part of the closed container.
The oil separation plate has a hollow hole with a cylindrical wall standing upright at a right angle with respect to the disc portion at the center of rotation, and the drive shaft is fitted and held in the inner diameter of the cylindrical wall by an interference fit. Therefore, there is no hole communicating between the upper and lower surfaces of the oil separation plate. Therefore, all the gas from the rotor through-hole to the discharge port at the upper part of the sealed container goes around the outer periphery of the oil separation plate. As a result, the rotational motion is given strongly, and the second effect of increasing the oil separation efficiency is obtained. Have. Further, as described above, since the oil separation plate is fitted and held on the drive shaft by an interference fit, there is a third effect that allows a simple structure without increasing the number of components.

Embodiment 1 FIG.
1 is a cross-sectional view of a hermetic electric compressor according to Embodiment 1 of the present invention. In the figure, a DC motor 2 and a compression mechanism section 3 are fixed in the sealed container 1, and lubricating oil 4 for lubricating the compression mechanism is sealed at the bottom of the sealed container 1. A discharge pipe 5 is fitted into the upper part of the sealed container to form a discharge port 5a. The DC motor 2 includes a stator 2a and a rotor 2b, and a drive shaft 6 is fitted into the rotor 2b. The rotation of the rotor is transmitted to the compression mechanism unit 3 by the drive shaft 6. A disk-shaped oil separation plate 7 having an outer diameter smaller than the outer diameter of the rotor is held at the upper end of the drive shaft, and rotates together with the rotor. Further, there is a suction muffler 8 outside the sealed container, and the suction muffler is connected to a compression mechanism part in the sealed container by a suction pipe 9.

The compression mechanism section 3 is a crankshaft 10 having an eccentric shaft, the cylinder 11, and a bearing section into which the crankshaft 10 is rotatably inserted , and is closed up and down the cylinder 11. Upper and lower bearings 12 and 13 having end plates, a rolling piston 14 that is rotatably inserted in the eccentric shaft and revolves within the cylinder 11 by rotation of the crankshaft 10, and one end abutting the outer diameter of the rolling piston 14 The so-called rotary compressor is provided with a plate-like vane (not shown) that reciprocates in a groove provided in the cylinder 12.

The configuration of the DC motor 2 will be described with reference to FIG. FIG. 2 shows an AA cross section in FIG.
The rotor 2b is formed by caulking together a rotor core 15 made of laminated steel plates, upper and lower end plates 16 and 17 that also serve as a rotation balancer, and a plurality of permanent magnets 18 with a plurality of fixing rivets 19. . The rotor is provided with a plurality of through holes 20 having a total cross-sectional area A ₁ as first gas flow paths.
The stator 2 a is formed by a so-called concentrated winding method in which the winding 22 is directly wound around the tooth portion 21 a of the iron core 21 with the insulator 23 interposed therebetween. The iron core 21 is formed of a split core having a movable portion 21b that can be bent in a hinge shape for each tooth portion. Since the method is adopted, the gap in the winding accommodating slot is kept low. There is an air gap 24 between the inner diameter of the teeth and the outer diameter of the rotor, and a second gas flow path having a total cross-sectional area A ₂ together with a groove 25 formed from the opening of the winding accommodating slot to the inner peripheral surface of the stator 2a. Is forming. However, the area A ₂ is suppressed to be smaller than the area A ₁ .
Further, the outer periphery of the iron core 21 has a plurality of notches 21c, and a third gas flow path having a total cross-sectional area A ₃ is formed between the notch 21c and the sealed container 1. However, the area A ₃ is smaller than both A ₁ and A ₂ .

The present embodiment will be described with reference to FIG. 3 and FIG. 3 is an enlarged view of the vicinity of the oil separation plate in FIG. 1, and FIG. 8 is a perspective view of the oil separation plate 7. The oil separation plate 7 has a hollow hole 7c having a cylindrical wall 7b extending integrally from the disc portion 7a in the axial direction of the drive shaft and standing upright at a right angle to the disc portion 7a. The cylindrical wall 7b has an inner diameter that is smaller than that of the drive shaft 6. The drive shaft 6 is inserted into the inner diameter of the cylindrical wall 7b by press-fitting or shrink fitting to close the hollow hole 7c and separate oil. The plate 7 is held at a predetermined distance H from the upper end of the through hole 20 of the rotor. At this time, the predetermined interval H is set within a range of ± 50% with respect to the equivalent radius R of the first gas flow path. Here, R is an equivalent radius of the first gas flow path, and is defined by the following equation.
R = √ (A ₁ / π) (Formula 1)
Here, π is the circumference ratio.
The outer diameter D1 of the oil separation plate is set to be smaller than the outer diameter D2 of the rotor and larger than the outer end position D3 of the rotor through hole 20 forming the first gas flow path.

Next, the operation of the present embodiment will be described with reference to FIGS.
The hermetic electric compressor of this embodiment is configured as described above, and the low-pressure refrigerant gas sent from the suction muffler 8 to the compression mechanism unit 3 is compressed by the compression mechanism unit 3 and is contained in the hermetic container 1. Released. Since the lubricating oil 4 adheres to the compression mechanism unit 3, the lubricating oil is mixed in the discharge gas in the sealed container. The discharge gas mixed with the lubricating oil passes through the first to third gas flow paths penetrating the DC motor 2 in the sealed container and is sent out of the sealed container from the discharge port 5a at the upper part of the sealed container. At this time, most of the discharge gas passes through the first and second flow paths having a large area toward the discharge port at the top of the closed container. Since the third gas channel has a small area and a large channel resistance, the refrigerant gas directed to the discharge port hardly flows. In particular, the discharge gas that has passed through the first gas flow path, that is, a plurality of through-holes communicating with the upper and lower ends of the rotor in the axial direction, is blown to the oil separation plate held immediately after. At this time, a part of the lubricating oil adheres to the oil separation plate and is separated from the refrigerant gas by being blown off in the outer circumferential direction as the oil separation plate rotates. Thereafter, since there is no hole in the oil separation plate, all the refrigerant gas goes to the discharge port while going around the outer periphery of the oil separation plate. In this process, the discharged gas is given a rotational motion as the oil separation plate rotates, and the lubricating oil remaining in the discharged gas is separated by centrifugal force due to the difference in specific gravity. As described above, only the refrigerant gas having a low mixing ratio of the lubricating oil reaches the discharge port, and the oil circulation rate of the refrigerant gas released from the sealed container to the refrigeration cycle is kept low. On the other hand, the separated lubricating oil is dropped downward from the third gas flow path where the upward refrigerant gas flow is minute.

  As described above, the hermetic electric compressor according to the present embodiment provides a large amount of discharge gas to the oil separation plate held immediately after the first gas passage having the largest area in the rotor. The oil separation effect can be enhanced.

Further, since the predetermined interval H at which the oil separation plate 7 is held away from the upper end of the first gas flow path is set close to the equivalent radius of the first gas flow path, the first gas flow path is Rotational motion can be imparted to the discharge gas that has passed through the first gas flow path without hindering the flow of the discharge gas that passes.
This will be described in detail with reference to FIG. FIG. 5 shows the relationship between the ratio H / R of the predetermined interval H at which the oil separation plate 7 is held away from the first gas flow path and the equivalent radius R of the first gas flow path, and the oil circulation rate. Is shown. When H is too small, the first gas flow path is closed, so the flow rates of the second and third gas flow paths increase, and the oil wraps up, increasing the oil circulation rate (A in the figure). Alternatively, when H is excessive, the discharge gas that has passed through the first gas flow path flows around the oil separation plate, so the effect of oil separation is reduced, and the oil circulation rate when the oil separation plate is not installed (dotted line in the figure) (B in the figure). According to the present invention, since H is set within a range of ± 50% with respect to R, oil can be separated efficiently and the oil circulation rate can be kept low.

Here, the superiority in the present embodiment will be described below in relation to the manufacturing method of this type of hermetic electric compressor.
FIG. 4a shows a step of inserting the drive shaft 6 of the pre-assembled compression mechanism section 3 into the pre-assembled rotor 2b, which is a part of the compressor assembly step in the present embodiment. When the inverted compression mechanism 3 is inserted into the rotor 2b held by the holding jig 26 from above, the guide jig 27 inserted into the rotor from the opposite side of the compression mechanism reaches the drive shaft. By doing so, the drive shaft can be inserted into the rotor while maintaining a proper positional relationship between the drive shaft and the rotor. This process is a general process even in a conventional hermetic electric compressor of this type that does not depend on the present invention.
As a method for holding the oil separation plate, a method in which the oil separation plate 7 is fixed to the rotor 2b in advance by the rivet 19 is generally used. In this case, in order to insert the guide jig 27, FIG. As shown, the oil separation plate requires a hollow hole 7c. Even after assembly, the oil separation plate hollow hole 7c communicates with the upper and lower surfaces of the oil separation plate 7, so that the discharged gas that has passed through the first gas flow path is sealed through the oil separation plate hollow hole. Directly reaches the discharge port at the top of the container. Therefore, there is a drawback that the oil separation effect cannot be obtained.
In this embodiment, after the step of inserting the drive shaft 6 into the rotor 2b, the manufacturing method is such that the drive shaft is fitted and fixed in the hollow hole of the oil separation plate. There are no communicating holes. Therefore, a high oil separation effect can be obtained.
Alternatively, when a method of preventing the communication by using a spacer between the oil separation plate and the rotor in the method of rivet fixing the oil separation plate to the rotor in advance, not only will the number of parts increase, but also the gas flow path However, in this embodiment, the hole installation region penetrating the rotor has a high degree of freedom.

  In addition, in this embodiment, the oil separation plate is the center of rotation compared to the method of holding the oil separation plate on the drive shaft using a C-shaped clip or the like, which is known as another method for holding the oil separation plate. Since the cylinder wall is integrally fixed to the drive shaft with an interference fit, the oil separation plate can be easily and accurately attached, and the oil separation performance can be improved, and the number of parts can be reduced. Have. Further, since it can be manufactured by one action by press-fitting, assembly automation in mass production is easy, and there is an advantage that the tact time can be shortened. FIG. 7 shows a press-fitting process of the oil separator in the present embodiment.

Furthermore, the present embodiment has an effect that the following advantages can be obtained at the same time.
Advantage 1: Since a small-sized and high-magnetism rare earth magnet is used for the rotor, the magnetic flux passing through the rotor core is hardly obstructed even if a large-sized through hole is formed in the rotor core, so that the iron loss in the rotor is deteriorated. It is suppressed and the motor efficiency can be kept high. Further, since the cooling effect by the gas flow path of the rotor can be expected, it is possible to employ a magnet having the characteristic of demagnetizing at a relatively low temperature, and the material cost can be reduced.
Advantage 2: The second gas flow path formed by the notch of the stator iron core rather than the second gas flow path constituted by the air gap 24 and the groove portion 25 formed from the opening of the winding accommodating slot to the inner peripheral surface of the stator. Since the volume of the stator core can be increased and the iron loss in the stator can be improved, the motor efficiency can be kept high.
Advantage 3: In this embodiment, the gas passage is not expected to have a gap in the winding accommodating slot, and a sufficient oil separation effect can be expected even if the gap is minimized. In this embodiment, since the concentrated winding method using the split core is adopted for the stator, the winding space factor can be increased until the gap in the winding accommodating slot becomes smaller compared to the general concentrated winding method. Since the copper loss can be reduced, the motor efficiency can be kept high.

In the above description, the description has been made assuming a single rotary compressor having only one cylinder, but the mechanism of the compression mechanism such as a twin rotary that performs compression with a plurality of cylinders or a scroll compressor is different. In this case, it goes without saying that the present invention is effective as long as the configuration is such that the discharge gas is discharged from the compression mechanism into the sealed container and the refrigerant is sent out from the discharge port located at a position separated from the motor.
Further, in the oil separation plate 7, as shown in FIG. 9, the vicinity of the outer periphery of the disc portion 7a may be gradually lowered downward as it goes outward. In this case, since the refrigerant gas blown to the vicinity of the outer periphery of the disk portion by the centrifugal force accompanying the rotation of the rotor heads downward without being obstructed by the flow, the degree to which the oil is rolled up is reduced, and the refrigerant and the oil Is more efficiently separated.
In the above description, the DC motor is taken as an example, but it is needless to say that the present invention is not limited to this. For example, an induction motor may be used.

Moreover, since it has a particularly large effect when employing the compressor of the embodiment in a refrigeration cycle apparatus using the CO ₂ refrigerant, adding explained below. CO ₂ refrigerant has the advantage that it is a natural refrigerant and has a low global warming potential compared to HFC refrigerant, but it has a high operating pressure, so it has high pressure resistance for refrigeration cycle components such as compressor sealed containers. However, there is a disadvantage that an increase in material cost and an increase in product weight are inevitable due to an increase in the thickness of the container. In the compressor according to the present embodiment, the gas passage area of the compressor motor and the oil separator plate are optimized, so that the gas passage area of the compressor motor can be kept to a minimum. Therefore, the outer diameter of the compressor motor for securing the output necessary for compression can be minimized. Since the relationship between the inner radius r, the container thickness t, and the pressure limit Pr can be generally expressed by the equation (2), the inner diameter of the sealed container can be reduced, so that the pressure resistance level can be secured with a small thickness. become.
Pr = σ _B (t / r) σ _B is a constant (Formula 2)
Moreover, the relationship between the container inner radius r, the container thickness t, and the container mass m is shown in FIG. As shown in the figure, when the pressure level is made equal, the container mass is reduced by a quadratic function by reducing the inner radius of the container. This embodiment is particularly effective for reducing the material used in the cycle apparatus using a high-pressure refrigerant such as CO ₂ .

It is sectional drawing of the hermetic electric compressor in Embodiment 1 of this invention. It is sectional drawing of the direct-current motor part in Embodiment 1 of this invention. It is a principal part fragmentary sectional view of the hermetic electric compressor in Embodiment 1 of this invention. It is explanatory drawing which shows the compressor assembly process in this invention. The relationship between the ratio H / R of the predetermined interval H at which the oil separation plate 7 is held away from the first gas flow path and the equivalent radius R of the first gas flow path, and the oil circulation rate in the present invention. It illustrates. It is explanatory drawing which shows the relationship between an airtight container internal diameter, the container thickness, and a container mass. It is explanatory drawing which shows the compressor assembly process in this invention. It is a perspective view of the oil separation board in Embodiment 1 of this invention. It is sectional drawing of another oil separation board in Embodiment 1 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Airtight container, 2 DC motor, 2a stator, 2b rotor, 3 compression mechanism part, 4 lubricating oil, 5 discharge pipe, 5a discharge port, 6 drive shaft, 7 oil separation plate, 7a disk part , 7b cylindrical part , 7c Hole, 8 Suction muffler, 9 Suction pipe, 10 Crankshaft, 11 Cylinder, 12 Upper bearing, 13 Lower bearing, 14 Rolling piston, 15 Rotor core, 16 Upper end plate, 17 Lower end plate, 18 Permanent magnet, 19 Rivet, 20 Through-hole, 21 iron core, 21a teeth part, 21b movable part, 21c notch, 22 winding, 23 insulator, 24 air gap, 25 groove part, 26 holding jig, 27 guide jig.

Claims (6)

A sealed container having a discharge port above a predetermined position;
A motor comprising a stator provided in the hermetic container and a rotor disposed inside the stator;
A compression mechanism that is provided below the motor in the sealed container and is driven by a drive shaft that is fitted into the rotor;
Lubricating oil that lubricates the compression mechanism is sealed in the bottom of the hermetic container, and at least the rotor of the motor is formed with a gas flow path including a plurality of through-holes communicating in the axial direction at both upper and lower ends. A substantially disk-shaped oil separation plate that is held at a predetermined interval from the upper end of the part and rotates together with the rotor, and a hermetic electric compressor comprising:
The oil separation plate includes a disc portion and a cylindrical wall that is erected at a right angle to the disc portion and has a hollow hole formed in a rotation center portion, and the inside of the cylindrical wall is the drive The shaft is inserted and held with an interference fit,
The motor includes a first gas flow path having a total cross-sectional area A ₁ including a plurality of through-holes communicating with the upper and lower ends of the rotor in the axial direction;
A _second gas flow having a total cross-sectional area A ₂ composed of an air gap secured between the outer peripheral surface of the rotor and the inner peripheral surface of the stator and a groove portion formed from the opening of the coil receiving slot in the stator to the inner peripheral surface of the stator. Road,
The motor comprises a plurality of through-holes formed on the outer peripheral side of the stator winding and on the inner side of the inner wall of the airtight container and communicating the upper and lower ends of the motor in the axial direction, and is smaller than both A ₁ and A ₂ hermetic electric compressor, characterized in that the formation of the third gas flow path including the cross-sectional area a _3. The A ₁ is larger than the A ₂ , and the outer diameter of the disk portion of the oil separation plate is larger than the plurality of through-hole portions communicating with the upper and lower ends of the rotor in the axial direction and larger than the outer diameter of the rotor. The hermetic electric compressor according to claim 1 , wherein the hermetic electric compressor is small. The predetermined interval at which the oil separation plate is separated from the upper end of the first gas flow path is ± 50% with respect to the radius of an equivalent circle having the total cross-sectional area of the first gas flow path as A ₁ . hermetic electric compressor according to claim 1 or 2, characterized in that in the range. The hermetic electric compressor according to any one of claims 1 to 3 , wherein the oil separation plate has a disk portion formed such that the vicinity of the outer periphery gradually descends outward. A refrigeration cycle apparatus using the hermetic electric compressor according to any one of claims 1 to 4 . The refrigeration cycle apparatus according to claim 5 , wherein a CO ₂ refrigerant is used as the refrigerant.

Images