JP3420641B2 - Hermetic compressor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hermetic compressor used in a refrigeration cycle such as an air conditioner.

[0002]

2. Description of the Related Art A hermetic compressor used in a refrigerating cycle such as an air conditioner is provided with an electric motor part in an upper part and a compressor part in a lower part of a hermetic case, and a refrigerant (gas refrigerant) compressed by the compressor part is supplied. It is guided to the upper space in the sealed case through the gap of the electric motor part, and then discharged to the outside (during the refrigeration cycle) through the discharge port in the upper part of the sealed case. Lubricating oil is contained in the bottom portion of the closed case, and the lubricating oil secures the mechanical lubricating action of the compressor and cools the compressor.

In such a hermetic compressor, when the compressed refrigerant flows into the upper space in the hermetic case, the mist-like lubricating oil is blown up and floats along with it. Due to its heavy specific gravity, the floating lubricating oil falls to the bottom through the oil return flow path between the motor part and the case inner peripheral surface, but part of it flows out from the upper space to the outside together with the refrigerant. . The refrigerant that has flowed out circulates in the refrigeration cycle and eventually returns to the compressor.

However, not only the lubricating oil reaching the upper space is blown up through the gap of the electric motor portion, but actually,
There is also a portion that blows up through the oil return flow path between the electric motor section and the inner peripheral surface of the case. This amount tends to increase the amount of lubricating oil flowing out of the compressor.

If the amount of lubricating oil flowing out is large, the amount of lubricating oil in the hermetically sealed case tends to be insufficient, impairing the lubricating action of the compressor part, or impairing the cooling action for the compressor part.

On the other hand, in the compressor disclosed in Japanese Utility Model Publication No. 62-42138, for example, a cylindrical oil separator is provided between the electric motor section and the compressor section in the closed case. Also,
In the compressor disclosed in Japanese Utility Model Laid-Open No. 55-78783, an oil shield cylinder is provided between the electric motor section and the compressor section in the closed case.

The oil separator or the oil shield cylinder functions to prevent the mist-like lubricating oil from flowing into the oil return passage between the electric motor section and the inner peripheral surface of the case. That is, the lubricating oil flowing in the upper space is limited to the amount of being blown up through the gap of the electric motor section, and thus the amount of lubricating oil flowing out of the compressor is suppressed.

[0008]

The space for providing the above oil separator and oil shield cylinder, that is, the space between the electric motor section and the compressor section is quite narrow. For this reason, the oil separator and the oil shield cylinder are naturally formed in a thin plate shape, and are formed of an insulating material having poor rigidity because it is necessary to secure an electrical insulating action with respect to the winding of the electric motor section.

If such an oil separator or an oil shield cylinder having a thin plate shape and poor rigidity is adopted, a large amount of noise and vibration will be generated during operation. This noise and vibration is unpleasant for the occupants of the dwelling where the air conditioner is installed.

The present invention takes the above circumstances into consideration,
In both the hermetic compressors according to the first and second aspects of the present invention, the outflow amount of the lubricating oil is suppressed to produce a good lubricating action of the compressor section and sufficient cooling of the compressor section without generating a large noise or vibration. The purpose is to obtain an effect.

[0011]

The hermetic compressor of the first invention comprises a hermetic case having a discharge port in the upper part, a stator provided in the upper part of the hermetic case, and a rotor inside the stator. A direct current motor, a compressor section provided in the lower part of the closed case, which is driven by the direct current motor to compress the refrigerant, a lubricating oil housed in the lower part of the closed case, and an inner periphery of the stator. A first flow path formed on the side of the DC motor to connect the upper and lower ends of the DC motor in the axial direction, and a second flow path formed on the outer peripheral side of the stator to connect the upper and lower ends of the DC motor to the axial direction. And the flow path resistance of the first flow path is set smaller than the flow path resistance of the second flow path.

The hermetic compressor of the second invention is the hermetic compressor according to the first invention, wherein the first flow path is an air gap secured between the inner peripheral surface of the stator and the outer peripheral surface of the rotor, and windings in the stator. A groove formed from the opening of the accommodation slot to the inner peripheral surface of the stator, and a plurality of through holes formed in the rotor, wherein the second flow path is between the outer peripheral surface of the stator and the inner peripheral surface of the sealed case. Is a flow path for oil return that is formed in.

[0013]

In the hermetic compressors according to the first and second aspects of the present invention, the compressed refrigerant and the lubricating oil can easily flow into the first flow path having the smaller flow path resistance, and the second flow path is accordingly increased. It becomes difficult to flow into. Therefore, the compressed refrigerant and the lubricating oil flowing in the upper space in the closed case are limited to substantially the amount passing through the first flow passage, and at the same time, the second flow passage is almost exclusively used for the original oil return from the upper space to the lower portion. Be converted.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 and 2, reference numeral 1 denotes a closed case, which is a case body 1 having a cylindrical shape with a bottom and an opening at the top.
a and an upper case 1b that closes the upper opening of the case body 1a. A pair of suction pipes 4 are formed in the lower part of the case body 1a, and a discharge pipe 6 is formed in the upper case 1b.

A muffler 5 for muffling is provided on the suction pipe 4. A discharge pipe 6 is connected to the discharge port 3. Then, from the discharge pipe 6 to the muffler 5, a refrigeration cycle mounted in the air conditioner is configured.

A brushless DC motor 10 is provided as an electric motor section in the upper part of the closed case 1. The brushless DC motor 10 includes a stator 11 and a rotor 12 provided inside the stator 11.

A large number of winding housing slots 13 are arranged on the inner peripheral surface of the stator 11, and a plurality of phase windings 14 are embedded and mounted in these slots 13. The rotor 12 is formed by stacking a large number of disc-shaped steel plates in the axial direction, passing a shaft 15 through a core portion, and housing four permanent magnet pieces 16 at a position surrounding the shaft 15.

That is, when the phase windings 14 of the stator 11 are sequentially energized, magnetic fields are sequentially generated in the phase windings 14 and the interaction between the magnetic fields and the magnetic fields generated by the permanent magnet pieces 16 of the rotor 12 causes the magnetic fields to interact. Rotational torque is generated in the rotor 12.

On the other hand, a compressor section 20 is provided at the bottom of the closed case 1. The compressor unit 20 has a main bearing 21 and a sub bearing 22 for supporting the shaft 15, and a pair of cylinders 23, 23 between the main bearing 21 and the sub bearing 22. Each of the cylinders 23 has a shaft 1
The eccentric portion 15a of No. 5 is accommodated, the roller 24 is attached to the outer periphery of the eccentric portion 15a, and the blade 25 is provided. The roller 24 and the blade 25 form the compression chamber 26, respectively. Both suction ports 2 communicate with these compression chambers 26. Further, in each cylinder 23, a discharge port 27 is formed at a position corresponding to each compression chamber 26.

That is, when the brushless DC motor 10 is driven to rotate the shaft 15, each roller 23 of the compressor section 20 is eccentrically rotated, and suction pressure is generated in each compression chamber 26. Due to this suction pressure, a refrigerant (gas) flows from each suction pipe 4 into each compression chamber 26. The refrigerant that has flowed in is compressed in each compression chamber 26 as it is, and is discharged from each discharge port 27 into the closed case 1.

Lubricating oil is contained in the bottom of the closed case 1. This lubricating oil is sucked up by a twisted plate-shaped oil pump provided at the lower end of a hollow hole formed in the axial direction of the shaft 15, and passes through a communication hole provided in the radial direction of the hollow hole of the shaft 15. Oil is supplied into the compressor unit 20. Thereby, the mechanical lubrication action of the compressor unit 20 is ensured and the compressor unit 20 is cooled. It should be noted that the lubricating oil is not always stored in the bottom portion, and as the compressor unit 20 is driven and the refrigerant is discharged from each of the discharge ports 27, a part thereof becomes a mist and the sealed case 1 It is blown up inside.

On the other hand, a first flow path is formed on the inner peripheral side (shaft 15 side) of the stator 11 so as to axially penetrate and communicate with both upper and lower ends of the brushless DC motor 10. The first flow path is for guiding the refrigerant discharged from the compressor section 20 to the upper space in the closed case 1, and includes the following.

(1) Inner peripheral surface of stator 11 and rotor 12
An air gap 41 secured between the air gap 41 and the outer peripheral surface of the. (2) The groove portion 42 formed from the opening of each slot 13 in the stator 11 to the inner peripheral surface of the stator 11.

(3) Each permanent magnet piece 1 in the rotor 12
6 is formed at a position closer to the inner peripheral side than the accommodating portion of 6, and the rotor 12
Four through holes 43 that pass through along the shaft direction. Further, on the outer peripheral side of the stator 11, there is formed a second flow path that axially penetrates and communicates with both upper and lower ends of the brushless DC motor 10. The second flow path is for returning the lubricating oil existing in the upper space in the closed case 1 to the lower part in the closed case 1, and is as follows.

(1) A large number of notched grooves 11a formed on the outer peripheral surface of the stator 11 along the shaft direction, and the gaps between these notched grooves 11a and the inner peripheral surface of the case body 1a. Serve as the oil return passages 44, respectively.

Since the rotor 12 has the permanent magnet 16 and its magnetic force is strong, the brushless DC motor 10 is more efficient than an AC motor having no magnetic force on the rotor. From margin of good in efficiency, the brushless DC motor 10, can be increased as compared with Eagya' flop between the stator 11 and the rotor 12 to the AC motor. In the case of an AC motor, it is necessary to make the diameter of the air gap as small as possible so as not to reduce the efficiency.

Further, the rotor 12 of the brushless DC motor 10 has a space in the radial direction of the rotor 12 due to the efficiency margin. Due to this space, the diameter of each through hole 43 can be made as large as possible.

[0028] Thus, by taking larger than the diameter of Eagya' flop you and the respective through holes 43 to the AC motor of equivalent capacity, the brushless DC motor 10 stator 11
As for the first flow path located on the inner peripheral side, the cross-sectional area in the direction orthogonal to the flow direction of the refrigerant increases.

Second position located on the outer peripheral side of the stator 11
The flow path 44 for returning oil, which is a flow path, has the same cross-sectional area in the direction orthogonal to the flow direction of the refrigerant as in the case of using an AC motor having the same capability.

By setting this cross-sectional area, the flow path resistance of the first flow path is made smaller than the flow path resistance of the second flow path. Next, the operation of the above configuration will be described.

When the brushless DC motor 10 is driven, the refrigerant is sucked into the closed case 1 from both suction pipes 4,
It is compressed in the compressor section 20. The compressed refrigerant is discharged into the space between the compressor unit 20 and the brushless DC motor 10, and together with the mist-like lubricating oil, the first flow path (air gap 41, each groove 42, 42) on the inner peripheral side of the stator 11. And each of the through holes 43) and the second flow passage (each oil return passage 44) on the outer peripheral side of the stator 11.

Here, the compressed and discharged refrigerant and lubricating oil easily flow into the first flow path having a smaller flow path resistance, and are less likely to flow into the second flow path. Therefore, the compressed refrigerant and the lubricating oil that flow in the upper space in the closed case 1 are limited to the amount that passes through the first flow path. That is, the amount of lubricating oil flowing in the upper space is smaller than in the conventional case.

The refrigerant flowing through the first flow path into the upper space in the closed case 1 is discharged from the discharge pipe 6 during the refrigeration cycle. Further, the lubricating oil floating in the upper space in the closed case 1 falls to the bottom through the second flow path due to the action of the upward flow restricted to the first flow path and gravity. In this case, the compressed and discharged refrigerant and lubricating oil are difficult to flow into the second flow path, so the second flow path is almost dedicated to the original oil return. That is, the lubricating oil that has reached the upper space efficiently drops to the lower portion.

Although a part of the floating lubricating oil flows out from the discharge pipe 6 together with the refrigerant, the lubricating oil that flows out circulates in the refrigeration cycle and eventually returns to the closed case 1. In this way, the compressed refrigerant and the lubricating oil are raised as much as possible through the first flow path, and the second flow path is dedicated as much as possible for the original oil return, so as to flow out from the closed case 1. The amount of lubricating oil decreases.

When the outflow amount of the lubricating oil is small, a good lubricating action of the compressor section 20 and a sufficient cooling action for the compressor section 20 can be obtained. In particular, no special member such as a conventional oil separator or an oil shield cylinder is provided inside the closed case 1, so that a large noise or vibration does not occur during operation.

By the way, for reference, there is "fluid average depth" as an index of flow path resistance. this is,
It is inversely proportional to the flow path resistance and is expressed by the following equation. Average depth of fluid M = cross-sectional area A / circumferential length L The cross-sectional area A is the cross-sectional area of the flow path (cross-sectional area in the direction orthogonal to the flow direction). The perimeter L is the length of the circumference (the length of the wetting edge) in contact with the fluid in the flow path.

For example, if the cross section of the flow path (the cross section in the direction orthogonal to the flow) is a square and the length of one side of the square is a, the peripheral length L = 4.a. As shown in FIG. 3, if the flow path has a circular cross section and the radius of the circle is r ₁ , the peripheral length L = 2 · π · r ₁ . As shown in FIG.
If the cross section of the flow path is annular and the annular width is (r ₃ −r ₂ ), the peripheral length L = 2 · π · r ₂ + 2 · π · r ₃ .

The peripheral length L of the first flow passage on the inner peripheral side of the stator 11 is the inner peripheral length of the stator 11, the outer peripheral length of the rotor 12, and the circumferential length of each through hole 43. It is a sum.
On the other hand, the peripheral length L of the second flow path on the outer peripheral side of the stator 11
Is the length of the outer circumference of the stator 11 and the case body 1a.
Is the sum of the inner circumferences of.

Assuming that the cross-sectional area A of the first flow path and the cross-sectional area A of the second flow path are the same, the flow path whose peripheral length L is shorter is the flow path whose peripheral length L is longer. The fluid average depth M is larger than that of the passage. That is, the flow path resistance is reduced.

Peripheral length L of each of the first flow path and the second flow path
Is arbitrary, and assuming that the respective cross-sectional areas A are significantly different from each other, the flow path having the larger cross-sectional area A has a larger average fluid depth M than the flow path having the smaller cross-sectional area A. Grows larger. That is, the flow path resistance is reduced.

The velocity (that is, flow velocity) of the fluid in the flow path is expressed by the following equation. Velocity V = Flow rate Q / Cross-sectional area A As shown in FIG. 5, considering the case where the flow of flow rate Q is divided into two flow paths, if each flow path has the same length d,
The respective flow rates Q ₁ and Q ₂ are the cross-sectional areas A ₁ and A of each flow path.
_It is generally considered to be proportional to ₂ .

Q ₁ = [A ₁ / (A ₁ + A ₂ )] · Q Q ₂ = [A ₂ / (A ₁ + A ₂ )] · Q Therefore, the flow velocities V ₁ and V ₂ of each flow path are as follows. become that way.

V ₁ = Q ₁ / A ₁ = Q / (A ₁ + A ₂ ) V ₂ = Q ₂ / A ₂ = Q / (A ₁ + A ₂ ) That is, the flow velocities V ₁ and V ₂ of the respective flow paths are Will be the same.

However, even if the cross-sectional area A of each flow path is the same, it is reasonable to consider that there is a difference in ease of flow depending on the respective fluid average depths M. In the example of FIG. 5, the cross-sectional areas A ₁ and A ₂ of the flow paths are the same, and the circumferential length of each flow path is L.
Assuming that ₁ and L ₂ have a relationship of L ₁ > L ₂ , the fluid average depths M ₁ and M ₂ of each flow path are represented by the following equations, and M ₁ <
The relationship of M ₂ arises.

M ₁ = A ₁ / L ₁ M ₂ = A ₂ / L ₂ From these, the flow rates Q ₁ and Q ₂ are calculated as follows.
The relationship of Q ₁ > Q ₂ occurs.

Q ₁ = [M ₂ / (M ₁ + M ₂ )] ・ Q Q ₂ = [M ₁ / (M ₁ + M ₂ )] ・ Q When the flow velocities V ₁ and V ₂ of each flow path are obtained, become that way.

V ₁ = Q ₁ / A ₁ V ₂ = Q ₂ / A ₂ Here, when the condition of A ₁ = A ₂ is added, the relationship of V ₁ > V ₂ occurs. That is, the flow velocity changes even with the same cross-sectional area.

On the other hand, regarding whether the fog droplets of the lubricating oil floating in the upper space in the closed case 1 continue to float or drop as they are, the buoyancy and gravity acting on the fog droplets, and the viscosity of the refrigerant. It is determined by the balance of the three. Equation 1 represents this balance.

[0049]

[Equation 1]

Here, r is the radius of the fog droplets of the lubricating oil, ρ is the oil density, ρ'refrigerant density, η is the viscosity of the refrigerant, V is the speed applied to the fog droplets, and g is the gravitational acceleration. When this is transformed, it becomes Equation 2.

[0051]

[Equation 2]

From this equation, the size of the fog that can float is
It can be seen that it is proportional to the square root of the flow velocity V. That is, the flow velocity V
The smaller is the size of the fog that can float. Therefore, if the flow passage resistance of the first flow passage is made smaller than that of the second flow passage as in the present embodiment, the flow velocity V of the second flow passage becomes smaller than that of the first flow passage, whereby the second flow passage is formed. The size of the mist of lubricating oil passing through the flow passage is smaller than that of the first flow passage, and the oil can easily return downward.

[0053]

As described above, in both the hermetic compressors of the first and second inventions, the flow passage resistance of the first flow passage formed on the inner peripheral side of the stator is set to the outer peripheral side of the stator. Since it is set to be smaller than the flow passage resistance of the second flow passage formed in the above, the amount of lubricating oil flowing out is suppressed and a good lubricating action and compression of the compressor portion are generated without generating large noise or vibration. A sufficient cooling effect for the machine part can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing the internal structure of an embodiment of the present invention.

FIG. 2 is a view of the configuration of the case body of the embodiment as seen from above.

FIG. 3 is a diagram for explaining a relationship between a cross-sectional area and a peripheral length according to the embodiment.

FIG. 4 is a diagram for explaining a relationship between a cross-sectional area and a peripheral length according to the example.

FIG. 5 is a diagram for explaining the relationship between the flow velocity, the flow rate, and the cross-sectional area according to the example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sealed case, 3 ... Discharge port, 10 ... Brushless DC motor, 11 ... Stator, 12 ... Rotor, 16 ... Permanent magnet, 41 ... Air gap (1st flow path), 42 ... Groove part (1st flow path), 43 ... through hole (first flow path), 44 ... oil return flow path (second flow path)

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02K 9/00-9/28 H02K 7/00-7/20 F04C 23/00-29/10 F04B 39 / 00-39/16

Claims (2)

(57) [Claims] 1. A sealed case having a discharge port at the top, a DC motor provided at an upper part of the sealed case, the stator and a rotor inside the stator, and a lower part of the sealed case, A compressor unit that is driven by a DC motor to compress the refrigerant, a lubricating oil housed in the lower portion of the hermetically sealed case, and is formed on the inner peripheral side of the stator, and the upper and lower ends of the DC motor are axially arranged. A first flow path communicating with the first flow path; and a second flow path formed on the outer peripheral side of the stator, the second flow path communicating the upper and lower ends of the DC motor in the axial direction. A hermetic compressor characterized by being set to be smaller than the flow path resistance of the second flow path. 2. The hermetic compressor according to claim 1, wherein the first flow path has an air gap secured between an inner peripheral surface of the stator and an outer peripheral surface of the rotor, and a winding housing slot in the stator. A groove formed from the opening to the inner peripheral surface of the stator and a plurality of through holes formed in the rotor, and the second flow path is formed between the outer peripheral surface of the stator and the inner peripheral surface of the closed case. A hermetic compressor characterized by being a flow path for returning oil.