JP2008240667A - Rotary compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a two-stage compression type rotary compressor capable of balancing the moment for inclining the whole shaft, by minimizing the mass of a balancer of a rotor. <P>SOLUTION: The shaft length L2 of a high stage side crankshaft 72 corresponding to a high stage side compression part 32, is set larger than the shaft length L1 of a low stage side crankshaft 73 corresponding to a low stage side compression part 31 (L2 > L1). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rotary compressor having a two-stage compression section including a low-stage compression section and a high-stage compression section. More specifically, the present invention prevents bending that occurs in a shaft connecting an electric motor and a compression section. And technology for improving reliability.

  In general, rotary compressors have a compression part placed under the sealed container where lubricating oil is stored to seal gaps in the compression chamber to reduce loss due to refrigerant leakage and to lubricate sliding parts such as bearings. Is done.

Further, in the two-stage compression type rotary compressor, the balance of the compression load torque generated in the two compression portions, the eccentric portion corresponding to the two compression portions, that is, the piston that performs the swiveling motion and the shaft that fits the piston are offset. In order to improve the balance of centrifugal force acting on the core, the compression phases of the low-stage compression section and the high-stage compression section are shifted by 180 °.
Further, a moment for tilting the entire shaft is generated by the centrifugal force acting on the two eccentric portions of the shaft and the two pistons that make a turning motion. Therefore, a balancer is attached to the top and bottom of the rotor of the electric motor so as to cancel out the moment to tilt the entire shaft.

  Here, in the two-stage compression type rotary compressor, it is necessary to make the volume of the high-stage compression section smaller than the volume of the low-stage compression section because of its compression characteristics. As a means for reducing the volume of the compression chamber, there are a method of reducing the thickness of the compression chamber, that is, the thickness of the cylinder, and a method of reducing the turning radius of the piston, but the centrifugal force acting on the eccentric part of the shaft and the piston. In any method, the high-stage compression section having a small volume is smaller.

  For this reason, as shown in Patent Document 1, the low-stage side compression part that acts with a large centrifugal force is the side closer to the rotor to which the balancer is attached, that is, the low-stage side compression part is above the high-stage side compression part. Means are known for reducing the mass of the balancer by arranging it.

Japanese Patent Laid-Open No. 11-230073

  However, when the low-stage compression section is disposed above the high-stage compression section, there are the following problems. That is, depending on the operating pressure condition and the rotational speed condition of the compressor, the oil level of the lubricating oil is lower than that of the compression part disposed on the upper side in the sealed container, and the upper compression part is exposed to the refrigerant gas. As a result, leakage loss occurs due to the refrigerant leaking into the suction chamber and the compression chamber through a gap between the vane and the vane groove.

  When the low-stage compression section is arranged on the upper side, the inside of the sealed container is the discharge pressure of the high-stage compression section, so the pressure difference between the suction chamber and the compression chamber is higher than when the high-stage compression section is arranged on the upper side. There is a problem that the amount of refrigerant leaking from the gap to the suction chamber and the compression chamber increases, and the efficiency of the compressor is further reduced.

  Therefore, an object of the present invention is to reduce the mass of the balancer in the configuration in which the high-stage compression unit is arranged on the upper side, thereby reducing the amount of shaft deflection and preventing seizure at the bearing unit and contact between the rotor and the stator. It is in providing the rotary compressor which can be performed.

  In order to achieve the above-described object, the present invention has several features described below. That is, the sealed shell has a two-stage compression section including a low-stage compression section and a high-stage compression section, and an electric motor that drives the two-stage compression section, and the high-stage compression section is disposed on the motor side. In the rotary compressor, the eccentric portion of the shaft corresponding to the low-stage side compression portion, that is, the axial length of the low-stage side crankshaft is L1, and the eccentric portion of the shaft corresponding to the high-stage side compression portion, that is, the high step When the length of the side crankshaft in the axial direction is L2, L2> L1.

  The invention described in claim 2 is characterized in that the rotation speed of the compression section is variable.

  According to the first aspect of the present invention, the mass of the balancer attached to the rotor can be reduced by making the axial length of the high-stage crankshaft longer than the axial length of the low-stage crankshaft. Therefore, it is possible to reduce the deflection of the entire shaft and prevent the bearing portion from being burned due to local excessive load and the contact between the rotor and the stator.

  According to the second aspect of the present invention, in the rotary compressor having a variable rotation speed, when the rotation speed is high, the centrifugal force acting on the upper balancer and the lower balancer is increased, and thus the deflection of the shaft is further increased. Therefore, the effect of the present invention is further increased.

  An embodiment of the present invention will be described with reference to FIG. The rotary compressor 1 includes a cylindrical sealed container 2 arranged in the vertical direction, and includes an electric motor 4 above the sealed container 2 and a compression unit 3 below.

  The hermetic container 2 includes a cylindrical main shell 21 and a dome-shaped top shell 22 and a bottom shell 23 that close the upper and lower portions of the main shell 21. The top shell 22 and the bottom shell 23 are fixed to the main shell 21 by welding. Has been.

  The top shell 22 is provided with a refrigerant discharge pipe 24 for discharging the refrigerant discharged from the compression unit 3 into the sealed container 2 to the outside of the sealed container 2.

  The stator 41 of the electric motor 4 is shrunk to the main shell 21, and the rotor 42 of the motor 4 is shrunk and fixed to the shaft 7 that mechanically connects the motor 4 and the compression unit 3. An upper balancer 43 and a lower balancer 44 are attached above and below the rotor 42 to balance the centrifugal force of the entire rotating component.

  The compression unit 3 includes a high-stage compression unit 32 on the upper side and a low-stage compression unit 31 on the lower side. The discharge side of the low-stage compression unit 31 and the suction side of the high-stage compression unit 32 are hermetically sealed. By connecting with an external intermediate connecting pipe 26, a two-stage compression section is configured.

  Next, the structure of each compression part 3 is demonstrated using FIG. FIG. 2 is a cross-sectional view of the lower stage compression section 31 in FIG. The high-stage compression section 32 has the same configuration except that the phase of the piston differs by 180 °.

  Each compression part 31 and 32 has cylinders 200 and 400 and cylindrical pistons 220 and 420 accommodated inside cylindrical cylinder bores 200a and 400a formed inside the cylinders 200 and 400, respectively. A working space for the refrigerant is formed between the inner walls of 200a and 400a and the outer peripheral surfaces of the pistons 220 and 420.

  The cylinders 200 and 400 are provided with cylinder grooves 200b and 400b from the cylinder bores 200a and 400a toward the outer periphery, and have flat plate-like vanes 230 and 430 in the cylinder grooves 200b and 400b.

  Springs 240 and 440 are provided between the vanes 230 and 430 and the inner wall of the sealed container 2, and the tip of the vanes 230 and 430 is brought into sliding contact with the outer wall of the pistons 220 and 420 by the biasing force of the springs 240 and 440. The space is divided into suction chambers V1, V2 and compression chambers C1, C2.

  Here, in order to make the working space volume of the high stage side compression part 32 smaller than the working space volume of the low stage side compression part 31, the cylinder 200, the piston 220, and the vane 230 on the high stage side have their respective axial thicknesses. It is thinner than the low-stage cylinder 400, piston 420, and vane 430.

  Next, the whole compressor 1 is demonstrated using FIG. 1 again. A main frame 100 on the high-stage cylinder 200, an intermediate partition plate 300 between the high-stage cylinder 200 and the low-stage cylinder 400, and a subframe 500 under the low-stage cylinder 400; The upper and lower sides of the two working spaces are closed by the main frame 100, the intermediate partition plate 300, and the sub-frame 500, thereby forming a sealed space.

  A high-stage discharge muffler cover 130 and a low-stage discharge muffler cover 510 are provided above the main frame 100 and under the subframe 500, respectively, and a high-stage discharge muffler chamber M2 for reducing pressure pulsation of discharged refrigerant. In addition, a low-stage discharge muffler chamber M1 is formed.

  The high-stage discharge muffler cover 130, the main frame 100, the high-stage cylinder 200, the intermediate partition plate 300, the low-stage cylinder 400, the subframe 500, and the low-stage discharge muffler cover 510 are integrated with bolts (not shown). Further, the outer periphery of the main frame 100 is fixed to the main shell 21 by spot welding.

  The main frame 100 and the sub frame 500 have bearing portions 110 and 502, and the shaft 7 is rotatably supported by fitting the shaft 7 to the bearing portions 110 and 502.

  The shaft 7 has two crankshafts 72 and 73 eccentric in directions different from each other by 180 °. One crankshaft 72 is fitted to the piston 220 of the high-stage side compression portion 32, and the other crankshaft 73 is The piston 420 of the low-stage compression unit 31 is fitted.

  As the shaft 7 rotates, the pistons 220 and 420 revolve while slidingly contacting the inner walls of the cylinder bores 200a and 400a, and the vanes 230 and 430 reciprocate following the reciprocating movements. And the volume of the compression chambers C1, C2 changes continuously. Thereby, the compression unit 3 repeats the suction and compression of the refrigerant.

  The suction chamber V <b> 1 of the low-stage compression unit 31 is connected to the refrigerant suction pipe 64 via a low-stage suction hole 410 provided in the cylinder 400. The compression chamber C1 of the low-stage compression unit 31 is connected to the intermediate connecting pipe 26 via a low-stage discharge hole 520 and a low-stage discharge muffler chamber M1 provided in the subframe 500.

  More specifically, a check valve 540 is provided in the low-stage side discharge hole 520, and the refrigerant suction pipe 64 is connected to the low-stage side suction hole 410 via the low-stage side suction connection pipe 411, and the intermediate connection pipe 26. Is connected to the low-stage discharge muffler chamber M1 through an intermediate discharge connection pipe 521.

  The suction chamber V <b> 2 of the high stage side compression unit 32 is connected to the intermediate connecting pipe 26 via a high stage side suction hole 210 provided in the cylinder 200. The compression chamber C2 of the high-stage compression section 32 is opened inside the hermetic container 2 through a high-stage discharge hole 120 and a high-stage discharge muffler chamber M2 provided in the main frame 100.

  More specifically, the high-stage discharge hole 120 is provided with a check valve 140, and the intermediate communication pipe 26 is connected to the high-stage suction hole 210 via the intermediate suction connection pipe 211.

  On the side surface of the compressor body 1, an accumulator 6 including an independent sealed container 61 is provided. A refrigerant return pipe 62 connected to the heat pump system side (not shown) is provided at the upper part of the accumulator 6, and an L-shaped one end extends to the upper part inside the accumulator 6 at the lower part of the accumulator 6, and the other end is the compressor 1. The refrigerant suction pipe 64 is connected to the suction chamber V1 of the low-stage compression section 31 from the side surface.

  Next, the flow of the refrigerant having the above configuration will be described with reference to FIGS. 1 and 2. The refrigerant flowing from the system side into the accumulator 6 through the refrigerant return pipe 62 is separated into a liquid refrigerant at the lower part of the accumulator 6 and a gas refrigerant at the upper part of the accumulator 6.

  As the low stage side piston 420 pivots and the volume of the low stage side suction chamber V1 expands, the gas refrigerant in the accumulator 6 passes through the refrigerant suction pipe 64 and the low stage side suction chamber V1 of the compressor body 1. Inhaled.

  After one revolution, the low-stage suction chamber V1 becomes a position that is blocked from the low-stage suction hole 410, and the refrigerant is compressed by switching to the low-stage compression chamber C1 as it is.

  When the compressed refrigerant reaches the pressure in the low-stage discharge muffler chamber M1, which is the outside of the check valve 540 provided in the low-stage discharge hole 520, that is, the intermediate pressure, the check valve 540 opens and the low pressure is reduced. It is discharged into the stage side discharge muffler chamber M1.

  The refrigerant is reduced in pressure pulsation that causes noise in the low-stage discharge muffler chamber M1 and then guided to the suction chamber V2 of the high-stage compression section 32 through the intermediate connecting pipe 26.

  The refrigerant guided to the suction chamber V2 of the high-stage compression section 32 is sucked, compressed, and discharged by the high-stage compression section 32 according to the same principle as that of the low-stage compression section 31, and is stored in the high-stage discharge muffler chamber M2. After reducing the pressure pulsation, it is discharged into the closed container 2.

  Further, it is guided to the upper part of the motor 4 through a core notch (not shown) of the stator 41 of the motor 4 and a gap between the core and the winding, and discharged to the system side through the discharge pipe 24.

  Next, the centrifugal force which acts on the rotating system components in the compressor having the above configuration will be described with reference to FIG. FIG. 3 is a diagram showing extracted rotary system components in the compressor.

Centrifugal force acting on the rotating system parts includes centrifugal force (F1) acting on the low-stage side crankshaft 73 and the low-stage side piston 420 fitted thereto, and high-stage side crankshaft 72 and this part. Centrifugal force (F2) acting on the high-stage piston 220, centrifugal force (F4) acting on the upper balancer 43 attached to the upper portion of the rotor 42, and acting on the lower balancer 44 attached to the lower portion of the rotor 42 There is centrifugal force (F3), and in order to balance these in the horizontal direction,
F1 + F4 = F2 + F3 Formula 1
To balance the moment to tilt the entire shaft, from the moment around the point of action of F3,
F1 × (Lx + Ly) = F2 × Ly + F4 × Lz Expression 2
Thus, F3 and F4, that is, the mass of the upper balancer 43 of the rotor 42 and the mass of the lower balancer 44 are determined so as to satisfy these two equations.

Here, Equation 2 is transformed and
F4 = (F1 × (Lx + Ly) −F2 × Ly) / Lz Expression 3
From Equation 3, F4 can be reduced as F1 is decreased and F2 is increased.

  That is, the upper balancer 43 of the rotor 42 can be made smaller as the mass of the lower stage crankshaft 73 is made smaller and as the mass of the higher stage crankshaft 72 is made larger.

  Here, a state in which the shaft is bent by the centrifugal force acting on the shaft 7 will be described with reference to FIG. FIG. 4 is an extracted view of the shaft 7 and the bearing 110 that supports the shaft.

  When the deflection of the entire shaft 7 increases, the shaft 7 deforms more than the gap between the shaft and the bearing 110, particularly in the bearing 110 of the main frame 100, and the shaft 7 and the bearing 110 are locally in contact with each other above and below the bearing 110. And cause burn-in.

  Therefore, the upper balancer 43 of the rotor 42 can be made smaller by making the length of the high-stage crankshaft 72 in the axial direction longer than the length of the low-stage crankshaft 73 in the axial direction. The deflection of the bearing portion 110 can be reduced, and the bearing portion 110 can be prevented from being burned due to excessive load and the contact between the rotor 42 and the stator 41.

  On the other hand, the following effects can also be obtained. That is, in a compressor used for a heat pump such as an air conditioner or a water heater, the suction pressure Ps and the discharge pressure Pd of the compressor change mainly depending on the outside air temperature condition. This means that the compression ratio ψ = Pd / Ps as a whole compressor is not constant and needs to correspond to a wide range.

Therefore, when the suction volume of the low-stage compression section 31 is V1, the suction volume of the high-stage compression section 32 is V2, and the specific heat of the compressed gas is κ, the loss of each compression section 31, 32 is ignored. The pressure ratio ψ1 of the low-stage compression unit 31 is ψ1 = (V1 / V2) ^κ . That is, the compression ratio ψ1 of the low-stage compression unit 31 is determined by the suction volumes of the two cylinders regardless of the outside air temperature condition.

  Therefore, in a condition in which the total pressure ratio ψ is large, such as a cooling operation in which the outside air temperature is particularly high and a heating operation in which the outside air temperature is particularly low, the pressure ratio ψ2 of the high-stage compression unit 32 is inevitably high. Become.

  That is, under such conditions, the load torque of the high stage compression unit 32 is larger than the load torque of the low stage compression unit 31. In order to support this load load, a crankshaft length of a predetermined length or more is necessary, but it is preferable to make the crankshaft longer than necessary because it may cause an increase in sliding loss in the crank portion. Absent.

  Thus, as described above, the axial length L2 of the high-stage crankshaft is set to be larger than the axial length of the low-stage crankshaft L1 (L2> L1), whereby reliability in each crank bearing portion is achieved. It is possible to achieve both improvement and efficiency improvement by reducing sliding loss.

  In this embodiment, the rotary compressor 1 is a compressor including a two-stage compression unit having a low-stage compression unit 31 and a high-stage compression unit 32, and the axial direction of the high-stage compression unit 32. A configuration in which the working space volume of the high-stage compression section 32 is made smaller than the working space volume of the low-stage compression section 31 by making the length smaller than the axial length of the low-stage compression section 31 is illustrated as a preferred embodiment. However, by setting the axial length of the compression unit 3 to be the same and making the turning radius of the high stage side piston 220 smaller than the turning radius of the low stage side piston 420, the working space volume of the high stage side compression unit 32 can be reduced. You may apply to the structure which did.

  Further, a two-stage compression rotary compressor configured to use a gas injection cycle as a refrigeration cycle and to allow injection refrigerant to flow into an intermediate pressure section between the low-stage compression section 31 and the high-stage compression section 32. But you can.

  In addition, as a compression mechanism of the compression unit 3, if the compressor utilizes the fact that the pistons 220, 420 are swung by the crankshafts 72, 73 and the volumes of the suction chambers V 1, V 2 and the compression chambers C 1, C 2 are changed. The compression mechanism is not limited to the embodiment.

The longitudinal cross-sectional view of the rotary compressor in one Embodiment of this invention. The cross-sectional view of the compression part of the rotary compressor in one Embodiment of this invention. The figure which showed the rotary system component of the rotary compressor in one Embodiment of this invention, and the centrifugal force which acts on this. The figure which showed the shaft deflection state by the centrifugal force of the rotary compressor in one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotary compressor 2 Sealing shell 3 Compression part (two-stage compression part)
4 Electric motor 41 Stator 42 Rotor 43 Upper balancer 44 Lower balancer 6 Accumulator 7 Shaft 71 Main shaft 72 High-stage crankshaft 73 Low-stage crankshaft 100 Mainframe 110 Main bearing 200 High-stage cylinder 220 High-stage rotary piston 300 Partition plate 400 Low-stage cylinder 420 Low-stage rotary piston 500 Subframe C1 Low-stage compression chamber C2 High-stage compression chamber V1 Low-stage suction chamber V2 High-stage suction chamber

Claims (2)

A closed container, a low-stage compression section and a high-stage compression section, and a low-stage eccentric section and a high-stage eccentric section corresponding to the low-stage compression section and the high-stage compression section. A shaft having a core, and an electric motor that is mechanically connected to the shaft and drives the low-stage compression section and the high-stage compression section,
A reciprocating motion is achieved in each of the low-stage compression section and the high-stage compression section, a piston that fits in the eccentric part of the shaft in the cylinder and pivots, and a vane groove in the cylinder. The vane that forms a refrigerant suction chamber and a compression chamber together with the cylinder and the piston by sliding the tip with the piston while being sandwiched between the low-stage compression section and the high-stage compression section, and the suction chamber and An intermediate partition plate that closes one end surface of the compression chamber, a bearing that rotatably supports the shaft, and a main frame and a subframe that close the one end surface of the suction chamber and the compression chamber;
In the rotary compressor having a means for communicating the discharge side of the low-stage compression section and the suction side of the high-stage compression section to form a two-stage compression section,
When the axial length of the eccentric portion of the shaft corresponding to the low-stage compression portion is L1, and the axial length of the eccentric portion of the shaft corresponding to the high-stage compression portion is L2, L2 > A rotary compressor characterized by being L1.   The rotary compressor according to claim 1, wherein the rotation speed of the compression unit is variable.

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