JP2013019325A - Refrigerant compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly-reliable refrigerant compressor while using a low-viscosity lubricant.SOLUTION: A monoester of 50-95 wt.% and 5-50 wt.% of at least one of diester or tetraester serve as base oil for ester oil 112 having VG3-VG22 reserved in a sealed container 101. The inclusion of an extreme-pressure additive in the base oil improves the abrasion resistance thereof even if low-viscosity base oil is used, thereby preventing extraordinary abrasion. As a result, a refrigerant compressor with increased efficiency and improved reliability can be achieved.

Description

  The present invention relates to a refrigerant compressor used for a refrigerator, an air conditioner and the like.

  Conventionally, as this type of refrigerant compressor, from the viewpoint of protecting the global environment, development of highly efficient refrigerant compressors that reduce the use of fossil fuels has been underway, and in particular, the viscosity of the lubricant is reduced. A technique for reducing sliding loss is known (see, for example, Patent Document 1 and Patent Document 2).

  Hereinafter, the conventional rotary compressor will be described with reference to the drawings.

  FIG. 4 is a cross-sectional view of a prior art hermetic electric refrigerant compressor. FIG. 5 is an enlarged view of a portion B in FIG.

  4 and 5, the hermetic container 2 accommodates an electric element 8 composed of a stator 4 and a rotor 6 and a compression element 10 that is rotationally driven by the electric element 8, and a diester at the bottom. Or the lubricating oil 12 which is ester oil of VG2-70 which consists of tetraesters is stored. The electric element 8 and the compression element 10 are assembled together to form a compression mechanism 14, and the compression mechanism 14 is elastically supported in the sealed container 2 by a plurality of coil springs 16.

  The compression element 10 is provided in the shaft 26 having the eccentric shaft portion 24 formed through the main shaft portion 20 and the flange portion 22, the cylinder block 32 forming the compression chamber 30, and the cylinder block 32, and supports the shaft 26. The main bearing 34 is provided. Further, the compression element 10 includes a piston 36 that reciprocates within the compression chamber 30, and a connection mechanism 38 that connects the piston 36 and the eccentric shaft portion 24. Further, the compression element 10 includes an upper race seating surface 42 provided at a lower portion 39 of the flange portion 22 of the shaft 26 and provided substantially at right angles to the axis 40 a of the main shaft portion 20, and the main bearing 34 above the main bearing 34. A thrust sliding portion 44 provided substantially perpendicular to the shaft center 40 b and supporting the load in the gravity direction of the shaft 26 and the rotor 6, and a thrust provided between the upper race seating surface 42 and the thrust sliding portion 44. A ball bearing 46 is provided to form a reciprocating hermetic compressor.

  The shaft 26 supplies an oil supply mechanism 50 having one end communicating with the lubricating oil 12 stored in the sealed container 2 and a part of the lubricating oil 12 pumped up by the oil supply mechanism 50 to the main shaft portion 20 to the thrust sliding portion 44. An oil supply groove 52 is provided.

  The electric element 8 includes a stator 4 fixed below the cylinder block 32 and a rotor 6 fixed to the main shaft portion 20 by shrink fitting.

  The thrust ball bearing 46 includes a plurality of balls 60, a holder portion 62 that holds the balls 60, and an upper race 64 and a lower race 66 that are respectively disposed above and below the balls 60. The upper race 64 is in contact with the upper race seating surface 42 of the collar portion 22, and the lower race 66 is in contact with the thrust sliding portion 44.

  The operation of the hermetic compressor configured as described above will be described below.

When the electric element 8 is energized from an external power source (not shown), the rotor 6 rotates and the shaft 26 rotates accordingly. Then, the motion of the eccentric shaft portion 24 is transmitted to the piston 36 via the coupling mechanism 38. As a result, the piston 36 reciprocates in the compression chamber 30, and the compression element 10 performs a predetermined compression operation.

  Thereby, the refrigerant gas is sucked into the compression chamber 30 from the cooling system (not shown), compressed, and then discharged again to the cooling system.

  At this time, the oil supply mechanism 50 of the shaft 26 draws up the lubricating oil 12 and lubricates each sliding portion (not shown). A part of the lubricating oil 12 is supplied from the oil supply groove 52 to the thrust sliding portion 44 to lubricate the thrust ball bearing 46.

  The weight of the shaft 26 and the rotor 6 is supported by a thrust ball bearing 46, and the ball 60 rolls between the upper race 64 and the lower race 66 when the shaft 26 rotates. As a result, the torque for rotating the shaft 26 is smaller than that of the thrust slide bearing. Therefore, the loss in the thrust bearing can be reduced and the input can be reduced, so that the compression operation can be performed with high efficiency.

JP 2002-156165 A JP 2005-127305 A

  However, when the viscosity of the conventional lubricating oil 12 is lowered to VG22 or less, the wear resistance is lowered. In particular, when the viscosity is VG10 or less, the ball 60 slips in addition to rolling between the upper race 64 and the lower race 66 when the thrust ball bearing 46 rotates. At this time, the ball 60 is in a point contact state between the upper race 64 and the lower race 66, which causes a problem that abnormal wear occurs and input increases.

  In general, a method of adding tricresyl phosphate (TCP) is adopted as an improvement in wear resistance such as point contact, but the conventional lubricating oil 12 is an ester composed of a diester or a tetraester. Since it is an oil, the adsorption reaction of tricresyl phosphate (TCP) is inhibited due to the high adsorptivity of the ester itself, and the effect as an extreme pressure additive is hardly recognized, and tricresyl phosphate ( There was a problem that the wear resistance could not be improved by adding TCP).

  The present invention solves the conventional problems. By using an ester oil containing 50 to 95 wt% monoester and containing 5 to 50 wt% of at least one diester or tetraester, the viscosity of the ester oil is determined. The purpose is to maintain the high efficiency and high reliability of the refrigerant compressor even if it is reduced.

  In order to solve the above-mentioned problems, the refrigerant compressor of the present invention uses a base oil of ester oil stored in a sealed container as a monoester: 50 to 95 wt%, and at least one kind of diester or tetraester is 5 to 50 wt%. The base oil contains an extreme pressure additive, and even when a base oil having a low viscosity is used, the wear resistance is improved and abnormal wear can be prevented.

  In the refrigerant compressor of the present invention, the base oil of the ester oil is monoester: 50 to 95 wt%, and at least one diester or tetraester is 5 to 50 wt%, and an extreme pressure additive is added to the base oil. By containing, the wear resistance is improved even when a base oil having a low viscosity is used, and a highly efficient and reliable refrigerant compressor can be obtained by preventing abnormal wear.

Sectional drawing of the refrigerant compressor in Embodiment 1 of this invention. Enlarged view of part A in FIG. The figure which showed the effect of the tricresyl phosphate (TCP) in Embodiment 1 Sectional view of a conventional refrigerant compressor Enlarged view of part B in FIG.

  According to the first aspect of the present invention, the ester oil having a viscosity of VG3 to VG22 is stored in an airtight container, and the electric element and a compression element that is driven by the electric element and compresses the refrigerant are accommodated in the oil container. The base oil is a monoester: 50 to 95 wt%, containing at least one diester or tetraester in an amount of 5 to 50 wt%, and the base oil contains an extreme pressure additive.

  As a result, even when the base oil has a viscosity of VG3 to VG22, the wear resistance is improved and abnormal wear can be prevented.

  The invention according to claim 2 is the invention according to claim 1, wherein the amount of the extreme pressure additive contained in the base oil is 0.1 to 3.0 wt%.

  As a result, even if the viscosity of the base oil is reduced, the wear resistance is improved and abnormal wear can be prevented.

  The invention according to claim 3 is the invention according to claim 1 or claim 2, wherein the extreme pressure additive is tricresyl phosphate (TCP), tributyl phosphate (TBP), triphenyl phosphate. This is a phosphorus additive such as fate (TPP).

  As a result, by forming an adsorption layer on the surface of the sliding portion, even if the viscosity of the base oil is reduced, the wear resistance is improved and abnormal wear can be prevented.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the refrigerant is a mixture containing R134a, R134a as a main component, R1234yf, or a mixture containing R1234yf as a main component. It is what.

  Thus, even if the refrigerant dissolves in the base oil and the viscosity of the base oil decreases, the wear resistance is improved by the effect of the extreme pressure additive, and abnormal wear can be prevented.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the compression element includes a thrust bearing portion that supports a rotor and a weight of a shaft connected to the rotor. And the thrust bearing portion is constituted by a thrust ball bearing.

  As a result, even if slip occurs due to point contact in the thrust ball bearing, abnormal wear can be prevented and efficiency reduction can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a cross-sectional view of a refrigerant compressor in Embodiment 1 of the present invention. FIG. 2 is an enlarged view of a part A in FIG. 1 in the first embodiment. FIG. 3 shows the effect of tricresyl phosphate (TCP) in the first embodiment.

  In FIG. 1 and FIG. 2, the hermetic container 102 accommodates an electric element 108 including a stator 104 and a rotor 106, and a compression element 110 that is rotationally driven by the electric element 108. An ester oil 112 is stored at the bottom of the sealed container 102. This ester oil 112 contained 3.0 wt% tricresyl phosphate (TCP) in a base oil containing 5 to 50 wt% monoester: 50 to 95 wt%, at least one kind of diester or tetraester. This is an ester oil 112 of VG5.

  The electric element 108 and the compression element 110 are assembled together to form a compression mechanism 114, and the compression mechanism 114 is elastically supported in the sealed container 102 by a plurality of coil springs 116.

  The compression element 110 includes a shaft 126 having an eccentric shaft portion 124 formed via a main shaft portion 120 and a flange portion 122, a cylinder block 132 that forms a compression chamber 130, a cylinder block 132, and the shaft 126. And a main bearing 134 for supporting the.

  Further, the compression element 110 includes a piston 136 that reciprocates within the compression chamber 130, and a connection mechanism 138 that connects the piston 136 and the eccentric shaft portion 124. The compression element 110 is provided at the lower portion 139 of the flange portion 122 of the shaft 126, the upper race seating surface 142 provided substantially at right angles to the axis 140 a of the main shaft portion 120, and the main bearing 134 above the main bearing 134. And a thrust sliding portion 144 that supports the load in the gravity direction of the shaft 126 and the rotor 106, and is provided between the upper race seating surface 142 and the thrust sliding portion 144. A thrust ball bearing 146 is provided, and these constitute a reciprocating hermetic compressor.

  The shaft 126 has an oil supply mechanism 150 having one end communicating with the ester oil 112 of VG5 stored in the sealed container 102 and a part of the ester oil 112 of VG5 pumped up by the oil supply mechanism 150 to the main shaft 120. And an oil supply groove 152 to be supplied to 144.

  The electric element 108 includes a stator 104 fixed below the cylinder block 132 and a rotor 106 fixed to the main shaft portion 120 by shrink fitting or the like.

  The thrust ball bearing 146 includes a plurality of balls 160, a holder portion 162 that holds the balls 160, and an upper race 164 and a lower race 166 that are respectively disposed above and below the ball 160. The upper race 164 is in contact with the upper race seating surface 142 of the collar portion 122, and the lower race 166 is in contact with the thrust sliding portion 144.

  The operation of the hermetic compressor configured as described above will be described below.

When the electric element 108 is energized from an external power source (not shown), the rotor 106 rotates and the shaft 126 rotates accordingly. Then, the turning motion of the eccentric shaft portion 124 is converted into a reciprocating motion via the coupling mechanism 138 and transmitted to the piston 136. As a result, the piston 136 reciprocates in the compression chamber 130, and the compression element 110 performs a predetermined compression operation.

  As a result, the refrigerant gas is sucked into the compression chamber 130 from the cooling system (not shown), compressed, and then discharged again to the cooling system.

  At this time, the oil supply mechanism 150 of the shaft 126 pumps up the ester oil 112 of VG5 and lubricates each sliding portion (not shown). A part of the ester oil 112 of VG 5 is supplied from the oil supply groove 152 to the thrust sliding portion 144 to lubricate the thrust ball bearing 146.

  The weight of the shaft 126 and the rotor 106 is supported by a thrust ball bearing 146, and the ball 160 rolls between the upper race 164 and the lower race 166 when the shaft 126 rotates. As a result, the torque for rotating the shaft 126 is smaller than that of the thrust slide bearing.

  Further, by using the ester oil 112 of VG5, even if the ball 160 slips due to point contact between the upper race 164 and the lower race 166 when the shaft 126 rotates, the added tricresyl is added. The phosphate (TCP) forms iron phosphide on the sliding surface. As a result, an increase in sliding loss due to abnormal wear can be prevented, and the superiority of rolling can be ensured. Along with this, the loss of all the sliding parts due to the lowering of the viscosity of the lubricating oil can be reduced and the input can be reduced, so that the compression operation can be performed with high efficiency.

  Here, referring to FIG. 3, tricresyl phosphate (TCP) when the base oil is monoester: 50 to 95 wt% and at least one of diester or tetraester is 5 to 50 wt%. The effect of will be described.

  FIG. 3 shows an R134a refrigerant (pressure: 0.4 MPa) atmosphere using a ball-on-disk wear tester, a Hertz contact load of 300 MPa, a sliding speed: 0.7 m / s, and a sliding time: Under the condition of 1800 sec, the conventional ester oil, the conventional ester oil containing 2.0 wt% of tricresyl phosphate (TCP), the base oil of the present invention, and the tricresyl phosphine of the base oil of the present invention Wear characteristics of oil containing 0.1 wt% of fate (TCP) and oil containing 3.0 wt% of tricresyl phosphate (TCP) in the base oil of the present invention (temperature of each oil: 80 ° C.) It is the result of evaluation.

  The evaluation was performed by determining the ratio of the wear amount of each oil to the wear amount of the conventional ester oil.

  From the results shown in FIG. 3, in the conventional ester oil composed of a diester and a tetraester, the wear amount ratio is almost 99.5% even if tricresyl phosphate (TCP) is contained. You can see that there is no. Further, in the base oil of the present invention in which the monoester: 50 to 95 wt% and at least one of diester or tetraester is 5 to 50 wt%, the wear amount ratio is 109.8% and the wear amount tends to increase. is there. This is considered to be due to the fact that the base oil of the present invention has 50 wt% or more of monoesters having lower adsorptivity than diesters and tetraesters.

However, in the case where the base oil of the present invention contains 0.1 wt% tricresyl phosphate (TCP), the wear rate was reduced to 80.3%. Furthermore, in the oil containing 3.0 wt% of tricresyl phosphate (TCP) in the base oil of the present invention, the wear rate was reduced by about half to 46.4%.

  This is because the tricresyl phosphate (TCP) contained in the oil has priority because the base oil of the present invention has 50 wt% or more of a monoester having a lower adsorptivity than diester and tetraester. Thus, it is possible to react with the sliding surface to generate an adsorption layer, and as a result, it is considered that the wear resistance is improved. In addition, since the wear resistance is improved by increasing the content of tricresyl phosphate (TCP) from 0.1 wt% to 3.0 wt%, the tricres in the base oil of the present invention is also improved. It can be seen that the inclusion of zircphosphate (TCP) works effectively.

  Therefore, the base oil in the first embodiment is monoester: 50 to 95 wt%, at least one diester or tetraester is 5 to 50 wt%, and the base oil has 3.0 wt% of tricresyl phosphate. Even if the viscosity of the base oil decreases due to the melting of the refrigerant by using the ester oil of VG5 containing (TCP), slippage due to point contact occurs in the thrust ball bearing, tricresyl phosphate (TCP) By generating the adsorption layer on the surface of the sliding portion, abnormal wear can be prevented, and reliability and efficiency can be improved.

  Moreover, although it was set as ester oil of VG5 which contains 3.0 wt% tricresyl phosphate (TCP) in base oil this time, from the result shown in FIG. 3, the amount of tricresyl phosphate (TCP) to contain is 0. It is clear that an effective effect can be obtained in the range of 0.1 wt% to 3.0 wt%.

  Furthermore, it is needless to say that the same effect can be obtained even if additives such as tributyl phosphate (TBP) and triphenyl phosphate (TPP) which are the same phosphorus extreme pressure additives are added in the same manner. .

  In addition, although R134a has been described as an example of the refrigerant this time, the mixture used is R1234yf, or R1234yf, the main component of which is compatible with ester oil as R134a and has a low adsorptivity of the refrigerant itself. The same effect can be expected from a mixture containing the main component.

  In the first embodiment, the case of a constant speed compressor has been described. However, as the speed of the refrigerant compressor is reduced along with the inverter, especially in the ultra-low speed operation of less than 20 Hz, Oil film generation becomes difficult, and in high speed operation at 60 Hz or higher, the temperature around the sliding portion further rises and the viscosity of the oil decreases and the lubrication state becomes severe. Even in such a case, the effect of the present invention is achieved. Needless to say, can be obtained remarkably.

  Further, in the first embodiment, the reciprocating refrigerant compressor has been described as an example, but the same applies to other compressors having a sliding portion and a discharge valve such as a rotary type, a scroll type, and a vibration type. Needless to say, an effect can be obtained.

  As described above, the refrigerant compressor according to the present invention can provide a highly reliable compressor using a low-viscosity lubricant, and thus can be widely applied to devices using a refrigeration cycle.

DESCRIPTION OF SYMBOLS 102 Sealed container 106 Rotor 108 Electric element 110 Compression element 112 Ester oil 126 Shaft 144 Thrust sliding part 146 Thrust ball bearing

Claims (5)

In the airtight container, ester oil having a viscosity of VG3 to VG22 is stored, an electric element and a compression element driven by the electric element and compressing refrigerant are accommodated, and the base oil of the ester oil is monoester: A refrigerant compressor comprising 50 to 95 wt%, 5 to 50 wt% of at least one diester or tetraester, and further containing an extreme pressure additive in the base oil. The refrigerant compressor according to claim 1, wherein the amount of the extreme pressure additive contained in the base oil is 0.1 to 3.0 wt%. The extreme pressure additive contained in the base oil is a phosphorus additive such as tricresyl phosphate (TCP), tributyl phosphate (TBP), or triphenyl phosphate (TPP). The refrigerant compressor described in 1. The refrigerant compressor according to any one of claims 1 to 3, wherein the refrigerant is a mixture containing R134a, R134a as a main component, R1234yf, or a mixture containing R1234yf as a main component. 5. The compression element according to claim 1, wherein the compression element includes a rotor and a thrust bearing portion that supports a weight of a shaft connected to the rotor, and the thrust bearing portion includes a thrust ball bearing. The refrigerant compressor according to item.