JP2020158566A - Producing method of lubricant composition, lubricant composition produced thereby, and compressor and freezing system using the same - Google Patents

Abstract

To provide a refrigerating machine oil (lubricant composition) and the producing method of the same, wherein the refrigerating machine oil has improved wear resistance of an Oldham's link during a high oil temperature and low speed operation.SOLUTION: The method for producing the lubricant composition of the present disclosure comprises: a selection step of selecting a lubricating reagent in a temperature range of 70°C or higher and 90°C or lower as an additive for improving lubrication characteristics; and a blending step of blending a selected lubricating reagent from 1 wt.% to 5 wt.% with respect to a base oil, wherein a decomposition start temperature is set to a temperature at which thermogravimetric change is 0.675% or more to 0.825% or less.SELECTED DRAWING: Figure 9

Description

The present invention relates to a method for producing a lubricating composition, a lubricating composition produced thereby, and a compressor and a freezing system using the same.

The freezer consists of at least a compressor, a condenser, an expansion valve and an evaporator. In the freezing device, each component is connected as a closed circuit by a refrigerant pipe, and the mixed liquid in which the refrigerant and the refrigerating machine oil are compatible circulates in the sealed system.

As part of measures against global warming, it has become essential to reduce the GWP (Global Warming Potential) of the refrigerant, and it has been a long time since we switched to HFC (hydrofluorocarbon) -based alternative refrigerants. As the HFC refrigerant, R410A, R32 and the like are known. The GWP of R32 is about 1/3 of that of R410A.

It is assumed that the HFC-based refrigerant is used under a higher pressure than the previously used CFC (chlorofluorocarbon) -based or HCFC (hydrochlorofluorocarbon) -based refrigerant. The pressure load is high in the compressor of the freezing device that uses the HFC-based refrigerant.

Refrigerating machine oil is responsible for lubricating the compressor. As described in Patent Document 1, the refrigerating machine oil includes a base oil and a lubricant.

Japanese Unexamined Patent Publication No. 2013-108033

One type of compressor is a scroll compressor equipped with a fixed scroll and a swivel scroll. The scroll compressor is equipped with an old dumb link to prevent the rotation of the scroll scroll and to perform the revolution rotation motion. The Oldham link slides back and forth along the groove as the swivel scroll moves.

In the use of HFC refrigerant in a high-load freezer, reducing wear of the Oldham link during low-speed operation is an issue. In particular, at low speeds, an oil film is unlikely to be formed, and the lubrication state becomes severe. In addition, when the oil temperature is high, the oil viscosity becomes low, and the lubrication characteristics become worse.

INDUSTRIAL APPLICABILITY The present invention has been made in view of such circumstances, and provides a refrigerating machine oil (lubrication composition) capable of improving the wear resistance of an Oldham link during high oil temperature and low speed operation from the current state, and a method for producing the same. The purpose is to do.

In order to solve the above problems, the method for producing a lubricating composition of the present disclosure, the lubricating composition produced by the method, and a compressor and a freezing system using the same adopt the following means.

In the present disclosure, the temperature at which the thermal weight change is 0.675% or more and 0.825% or less is defined as the decomposition start temperature, and as an additive for improving the lubrication characteristics, the decomposition start temperature is in the temperature range of 70 ° C. or more and 90 ° C. or less. Provided is a method for producing a lubricating composition comprising a selection step of selecting a lubricating reagent according to the above method and a blending step of blending the selected lubricating reagent with respect to the base oil in an amount of 1% by weight or more and 5% by weight or less.

Additives that improve lubrication properties are decomposed by heat and their weight changes (decreases). As a result of diligent studies, the present inventor found that the thermal weight decreased from the initial state by 0.675% or more and 0.825% or less, preferably 0.7125% or more and 0.7875% or less, and more preferably 0.75%. The temperature is defined as the decomposition start temperature, and the lubricating reagent is selected based on the decomposition start temperature.

As a result of diligent studies, the present inventors have found that when a tribo film is formed on an Oldham link, it should be evaluated under the condition that the thermogravimetric change is about ± 10% centered on 0.75%. The thermogravimetric rate of change is obtained from the thermogravimetric analysis chart. If the thermogravimetric change is too small (for example, 0.3%), it is difficult to see the inflection point. If too much, it is likely that the options will include lubricating reagents that do not improve wear resistance.

According to the study by the present inventors, the oil temperature during high oil temperature and low speed operation, in which wear was remarkable, was 70 to 90 ° C., and the temperature of the sliding portion of the Oldham link was a little over 90 ° C. The lubricating reagent whose decomposition is started in this temperature range (70 ° C. or higher and 90 ° C. or lower) can exhibit a function as an extreme pressure agent / anti-wear agent at the Older Link during high oil temperature and low speed operation. If the decomposition start temperature is too low, problems may occur in the chemical stability of the lubricating reagent such as oxidation stability. Further, if the decomposition start temperature is too high, a tribo film is difficult to be formed on the surface of the Oldham link during low-speed operation, and sufficient lubrication performance is not exhibited.

In one aspect of the above disclosure, the selection step comprises the step of selecting a high temperature lubricating reagent in a temperature range in which the decomposition start temperature exceeds 90 ° C. from among the additives that improve the lubricating characteristics. The step can include the step of blending the selected high temperature lubricating reagent into the base oil.

By further blending a high-temperature lubricating reagent in which decomposition is started at a temperature higher than that of the lubricating reagent (a tribo film is formed), a lubricating composition capable of exhibiting lubricating performance in a wide temperature range can be obtained.

The present disclosure also comprises an oldham link made of iron or aluminum alloy having a protruding key, and a member having a key groove into which the key is inserted and having a material different from that of the oldam link. Provides a compressor supplied with a lubricating composition made of an aluminum alloy or iron and produced by the production method described in the above embodiment.

By using different materials for the old dam link and the keyway, it is possible to prevent adhesion due to the same material during sliding.

The present disclosure also provides a freezing system equipped with the above compressor.

Further, the present disclosure includes a lubricating reagent selected from a base oil and an additive for improving lubrication characteristics, which exhibits a thermal weight change of 0.675% or more and 0.825% or less in a temperature range of 70 ° C. or higher and 90 ° C. or lower. To provide a lubricating composition containing 1% by weight or more and 5% by weight or less of the lubricating reagent with respect to the base oil.

By selecting and blending a lubricating reagent suitable for the usage environment based on the decomposition start temperature, it is possible to produce a lubricating composition having improved wear resistance of Oldham Link during high oil temperature and low speed operation. In the compressor to which the produced lubricating composition is supplied, the amount of wear at the old dam link portion can be suppressed.

It is a vertical sectional view which showed the scroll compressor which concerns on 1st Embodiment. It is a top view which showed the Oldham link and the upper bearing of FIG. FIG. 2 is a vertical cross-sectional view cut at the key position of the Oldham link. It is a block diagram of a refrigeration system. It is a thermogravimetric analysis chart figure of reagent A. It is a thermogravimetric analysis chart figure of the reagent B. It is a thermogravimetric analysis chart figure of reagent C. It is a figure which shows the relationship of the wear depth with respect to a refrigerant / refrigerating machine oil. It is a figure which shows the relationship between the amount of TBP addition and the wear depth.

Hereinafter, a method for producing a lubricating composition according to the present disclosure, a lubricating composition produced by the method, and an embodiment of a compressor and a freezing system using the same will be described.
[First Embodiment]
The method for producing a lubricating composition according to the present embodiment includes a selection step of selecting a lubricating reagent and a blending step of blending the selected lubricating reagent with the base oil.

(Selection process)
In the selection step, a lubricating reagent having a decomposition start temperature in the temperature range of 70 ° C. or higher and 90 ° C. or lower is selected as an additive for refrigerating machine oil for improving lubrication characteristics.

The decomposition start temperature is the temperature at which the lubricating reagent begins to change (decrease) in weight due to heat. The decomposition start temperature of the lubricating reagent can be obtained by thermogravimetric analysis. In thermogravimetric analysis, the temperature of a sample and a reference substance are changed in the same manner, the electrical energy required for the temperature is changed, and the reaction temperature such as oxidation / decomposition is specified. Thermogravimetric analysis can be performed by a differential thermal analyzer (DTA). If the decomposition start temperature of the reagent is published in a catalog or the like, it may be used.

In the present embodiment, the amount of weight change (decrease) from the initial state of the lubricating reagent is 0.675% or more and 0.825% or less, preferably 0.7125% or more and 0.7875% or less, and more preferably 0.75%. Is defined as the "decomposition start temperature".

(Mixing process)
In the blending step, the lubricating reagent is blended in an amount of 1 wt% or more and 5 wt% or less, preferably 1 wt% or more and 3 wt% or less with respect to the base oil. A lubricating oil composition (refrigerating machine oil) is obtained by blending a lubricating reagent with a base oil.

The base oil may be polyol ester (POE), polyvinyl ether (PVE), polyalkylene glycol (PAG), mineral oil and the like. The base oil may have an ester bond in its molecular structure.

In the compounding step, additives and the like that improve thermal stability may be further compounded.

(Application to compressor)
The lubricating composition produced according to the above embodiment is suitable for use in a scroll compressor equipped with an Oldham link.

The material of the oldham link is preferably iron or an aluminum alloy.

FIG. 1 is a vertical cross-sectional view of a scroll compressor to which a lubricating composition can be supplied.
The scroll compressor (scroll fluid machine) 1 is provided in the refrigerant circuit (refrigerant system) of the air conditioner, compresses the gas refrigerant supplied from the evaporator, and supplies the high-pressure gas refrigerant to the condenser. .. As shown in FIG. 1, the scroll compressor 1 includes a fixed scroll 3 and a swivel scroll 4 that revolves around the fixed scroll 3 in the housing 2.

The fixed scroll 3 is fixed to the housing 2 via an upper bearing 21, and includes a scroll-shaped wall body 33 erected on the end plate 31. The swivel scroll 4 includes a scroll-shaped wall body 43 erected on the end plate 41. The wall body 33 of the fixed scroll 3 and the wall body 43 of the swivel scroll 4 have substantially the same shape. A plurality of sealed compression spaces R1 are formed by rotating the swivel scroll 4 by 180 ° with respect to the fixed scroll 3 and engaging the walls 33 and 43 with each other.

The swivel scroll 4 revolves and swivels with respect to the fixed scroll 3 in a state where the rotation is restricted by the Oldham link 23.

The swivel scroll 4 is rotated by a driving motor 6. The rotary shaft 5 rotated by the motor 6 is connected to the swivel scroll 4 via the crank pin 27. The crank pin 27 is provided eccentrically with respect to the central axis of the rotating shaft 5. The crank pin 27 is rotatably connected to a boss formed on the back surface (lower surface in the drawing) of the end plate 41 of the swivel scroll 4 via a drive bush and a drive bearing 52. The rotating shaft 5 is rotatably supported by an upper bearing 21 and a lower bearing 24 fixed to the housing 2.

A storage area 26 for storing the lubricating composition (lubricating oil O) is provided in the lower portion of the housing 2. The lubricating oil O is pumped by a pump 54 provided at the lower end of the rotating shaft 5 through an oil supply path 53 inside the rotating shaft 5, and is provided around the lower bearing 24, the upper bearing 21, and the crank pin 27. , The swivel scroll 4, the old dam link 23, and the like.

The housing 2 is provided with a suction pipe 28 for sucking the low-pressure gas refrigerant and a discharge pipe 29 for discharging the compressed high-pressure gas refrigerant. The suction pipe 28 and the discharge pipe 29 are connected to a refrigerant circuit of an air conditioner (not shown).

The scroll compressor 1 described above operates as follows.
When a driving current is supplied to the stator 61 of the motor 6 from a power source (not shown), the rotor 62 of the motor 6 rotates and the driving force is output to the rotating shaft 5.
When the rotary shaft 5 is rotated, the driving force is swiveled and scrolled via a crank pin 27 provided at the upper end of the rotary shaft 5 eccentrically in one direction (eccentric direction) outward from the central axis of the rotary shaft 5. It is transmitted to 4. As a result, the swivel scroll 4 revolves around the fixed scroll 3 while being prevented from rotating due to the action of the old dumb link 23.

By turning the swivel scroll 4, the refrigerant flowing from the suction pipe 28 is sucked between the swirl scroll 4 and the fixed scroll 3. Then, as the swivel scroll 4 swivels, the volume of the compression space R1 between the swivel scroll 4 and the fixed scroll 3 decreases, so that the refrigerant is compressed in the compression space R1.

The compressed refrigerant is discharged to the refrigerant circuit by the discharge pipe 29 via the discharge port 32 of the fixed scroll 3 and the discharge port 38 of the discharge cover 37. A multi-port 32A is formed in the fixed scroll 3, and the multi-port 32A is provided with a lead valve 36 attached to the end plate 31 of the fixed scroll 3 via a retainer 35. The discharge port 38 of the discharge cover 37 is also provided with a lead valve 37B attached to the discharge cover 37 via the retainer 37A. When the pressure of the compressed refrigerant reaches a predetermined value, the refrigerant that pushes open the lead valves 36 and 37B is discharged to the condenser side of the refrigerant circuit.

2 and 3 show the Oldham link 23 shown in FIG. The old dam link 23 is provided above the upper bearing 21. Further, as shown in FIG. 1, the Oldham link 23 is provided on the back surface side of the end plate 41 of the swivel scroll 4.

As shown in FIG. 2, the Oldham link 23 has a substantially ring shape when viewed in a plan view. When viewed in a plan view as shown in FIG. 2, keys 23A projecting downward (upper bearing 21 side) are provided on both the left and right sides, that is, at the positions of 3 o'clock and 9 o'clock. Further, when viewed in a plan view as shown in FIG. 2, keys 23B protruding upward (on the swivel scroll 4 side) are provided on both the upper and lower sides, that is, at the positions of 6 o'clock and 12 o'clock. That is, the direction in which the two keys 23A are provided and the direction in which the two keys 23B are provided are provided so as to be orthogonal to each other. As shown in FIG. 3, each key 23A projecting downward is inserted into a key groove 21A formed in the upper bearing 21. Although not shown, each key 23B projecting upward is inserted into a key groove formed in the end plate 41 of the swivel scroll 4.

The upper bearing 21 and the swivel scroll 4 may be made of a material different from that of the Oldham link 23. When the material of the old dam link 23 is iron, the material of the keyway formed in the upper bearing 21 and the swivel scroll 4 is preferably aluminum. When the material of the old dam link 23 is aluminum, the material of the keyway formed in the upper bearing 21 and the swivel scroll 4 is preferably iron.

FIG. 4 is a block diagram of a freezing system including the scroll compressor 1. As shown in FIG. 4, for example, the refrigeration system includes a scroll compressor 1, a condenser 12, an expansion valve 13, and an evaporator 14, and each element flows and conveys a refrigerant through pipes 15a to 15d. It is connected.

In the refrigeration system, the condenser 12 condenses / liquefies the high-temperature and high-pressure refrigerant gas to dissipate heat, and the expansion valve 13 adiabatically expands the high-temperature and high-pressure liquid refrigerant that has passed through the condenser 12 to reduce the pressure, and the evaporator 14 However, the low-temperature low-pressure liquid refrigerant that has passed through the expansion valve 13 is evaporated / vaporized to absorb heat, and the scroll compressor 1 adiabatically compresses the low-temperature low-pressure refrigerant gas that has passed through the evaporator 14. The high-temperature and high-pressure refrigerant gas that has passed through the scroll compressor 1 is supplied to the condenser 12. By circulating the refrigerant as a heat transfer medium in the closed system in this way, heat transfer from the evaporator 14 to the condenser 12 is realized, and indoor air conditioning (heating and cooling) is enabled.

The lubricating composition supplied to the scroll compressor 1 goes around the refrigeration system including the evaporator 14, the expansion valve 13, and the condenser in a state of being mixed with the refrigerant, and returns to the compressor. The lubricating composition of the freezing system is sealed in the system together with the refrigerant and is used for the duration of the freezing system without being replaced.

In the actual machine environment, the temperature of the lubricating composition near the Oldam Link 23 during high oil temperature and low speed operation is 80 ° C. ± 10 ° C. Lubricating reagents with a decomposition start temperature in the temperature range of 70 ° C. or higher and 90 ° C. or lower form a low-shear tribo film on the sliding surface of the Oldham link during low-speed operation, lowering the friction coefficient of the sliding part, and as a result. It has the effect of reducing the amount of wear.

[Second Embodiment]
In this embodiment, the selection step may further include the step of selecting a high temperature lubricating reagent. The blending step may further include the step of blending the selected high temperature lubricating reagent into the base oil.

As the high temperature lubricating reagent, one or a plurality of additives having a decomposition starting temperature in a temperature range exceeding 90 ° C. are selected from among extreme pressure agents or additives functioning as lubricants.

The high temperature lubricating reagent is blended in an amount of 0.1 wt% or more and 5 wt%, preferably 0.1 wt% or more and 3 wt% or less with respect to the base oil.

〔test〕
(Selection of lubricating reagent)
The decomposition start temperatures of the following reagents A to C were obtained by thermogravimetric analysis.

A: Triphenyl phosphate (TPP)
B: Ethyl diethyl phosphonoacetate (JC-224)
C: Tributyl phosphate (TBP)

The results are shown in FIGS. 5 to 7 and Table 1.

FIG. 5 is a diagram showing a change in thermogravimetric analysis of reagent A (TPP). FIG. 6 is a diagram showing a thermogravimetric change of reagent B (JC-224). FIG. 7 is a diagram showing a change in thermogravimetric analysis of reagent C (TBP). In FIGS. 5 to 7, the horizontal axis is time (minutes), the left vertical axis is thermogravimetric change (%), and the right vertical axis is temperature (° C.).

In Table 1, the temperature at the time when the thermogravimetric change becomes 0.75% from FIGS. 5, 6 and 7 is read and described as the decomposition start temperature.

According to Table 1, reagents A, B, and C had low acid values. The decomposition temperatures of reagents B and C changed only a few degrees, but the decomposition start temperature differed by about 85 ° C.

(Abrasion resistance)
A wear resistance was evaluated by sliding a fixed piece and a rotating piece according to JIS K 7218 using a ring-on-disk refrigerant atmosphere friction test device.

The fixed piece was made of ADC12, which is an Al—Si—Cu alloy, and the surface was coated with hard alumite. As the rotating piece, a material made of flake graphite cast iron (FC200) was used.

In the actual machine, wear of the Oldham link is observed at high oil temperature and low speed. The test conditions were set according to the operating conditions of the actual machine.

Table 2 shows the test conditions.

The results are shown in Figures 8 and 9. FIG. 8 is a diagram showing the relationship of wear depth with respect to the refrigerant / refrigerating machine oil. FIG. 9 is a diagram showing the relationship between the amount of TBP added in Test 3 and the wear depth of the fixed piece. In the figure, the horizontal axis represents the amount of TBP added (wt%), and the vertical axis represents the wear depth (μm) of the fixed piece.

According to FIG. 8, the wear depth of TBP (1 wt%, 5 wt% added) in Test 2 was about 3 μm, which was the lowest as compared with Tests 1 and 3. The amount of wear in Test 3 with JC-224 added was lower than that without TBP in Test 2, but it was higher than in Test 1 with R410A refrigerant.

According to FIG. 9, in Test 2 in which TBP was added, an effect of improving wear resistance was observed when the amount of TBP added was 1% or more. In the test in which 1 wt% to 5 wt% of TBP was added, the wear depth of the fixed piece was about 2.5 to 3.2 μm. On the other hand, in the test in which 0.75 wt% and 0.25 wt% of TBP were added, the wear depths of the fixed pieces were 20 μm and 19 μm. From the above results, it was confirmed that the abrasion resistance was remarkably improved by adding 1 wt% or more of TBP.
According to FIG. 8, in Test 3 in which JC-224 was added, the wear depth of the fixed piece was 55 μm. In Test 1 in which the R410A refrigerant was used and no additive was added, the abrasion depth of the fixed piece was 43 μm, and the effect of improving the abrasion resistance with the oil to which 5 wt% of JC-224 was added was not observed.

Both JC-224 and TBP are phosphorus compounds, but they have different decomposition start temperatures. The decomposition start temperature of TBP is equal to or lower than the oil temperature at the start of the test of this test. Therefore, it is expected that TBP was decomposed during the test to form a tribo film, while at JC-244, where the decomposition start temperature was about 85 ° C higher than the test start temperature of this test, no tribo film was formed. ..

Although the Oldham link has been described in the above embodiment, the same effect can be expected in the blade sliding portion of the rotary compressor.

1 Scroll compressor (scroll fluid machine)
2 Housing 3 Fixed scroll 4 Swing scroll 12 Condenser 13 Expansion valve 14 Evaporator 15a to 15d Piping 21 Upper bearing 21A Key groove 23 Oldham link 23A Key 23B Key 24 Lower bearing 26 Storage area 27 Crank pin 28 Suction piping 29 Discharge piping 31 End plate 32, 38 Discharge port 32A Multiport 33 Wall body 35 Retainer 36 Reed valve 37 Discharge cover 37A Retainer 37B Reed valve 41 End plate 43 Wall body 52 Drive bearing R1 Compression space

Refrigerating machine oil is responsible for lubricating the compressor. As described in Patent Document 1, the refrigerating machine oil includes a base oil and a lubricant.

In the present disclosure, the temperature at which the thermal weight change is 0.675% or more and 0.825% or less is defined as the decomposition start temperature, and as an additive for improving the lubrication characteristics, the decomposition start temperature is in the temperature range of 70 ° C. or more and 90 ° C. or less. Provided is a method for producing refrigerating machine oil, which comprises a selection step of selecting a lubricating reagent in the above, and a blending step of blending the selected lubricating reagent with respect to the base oil in an amount of 1% by weight or more and 5% by weight or less.
The base oil may have an ester bond in its molecular structure.

It is a vertical sectional view which showed the scroll compressor which concerns on 1st Embodiment. It is a top view which showed the Oldham link and the upper bearing of FIG. It is a vertical cross-sectional view cut at the position of the key of the Oldham link of FIG. It is a block diagram of a refrigeration system. It is a thermogravimetric analysis chart figure of reagent A. It is a thermogravimetric analysis chart figure of the reagent B. It is a thermogravimetric analysis chart figure of reagent C. It is a figure which shows the relationship of the wear depth with respect to a refrigerant / refrigerating machine oil. It is a figure which shows the relationship between the amount of TBP addition and the wear depth.

According to Table 1, reagents A, B, and C had low acid values. The decomposition temperatures of reagents B and C changed by only a few ° C, but the decomposition start temperature differed by about 85 ° C.

The results are shown in Figures 8 and 9. FIG. 8 is a diagram showing the relationship of wear depth with respect to the refrigerant / refrigerating machine oil. FIG. 9 is a diagram showing the relationship between the amount of TBP added in Test 2 and the wear depth of the fixed piece. In the figure, the horizontal axis represents the amount of TBP added (wt%), and the vertical axis represents the wear depth (μm) of the fixed piece.

Claims (5)

The temperature at which the thermal weight change is 0.675% or more and 0.825% or less is defined as the decomposition start temperature, and as an additive for improving the lubrication characteristics, a lubricating reagent having the decomposition start temperature in the temperature range of 70 ° C. or more and 90 ° C. or less. And the selection process to select
A method for producing a lubricating composition, comprising a blending step of blending the selected lubricating reagent with respect to the base oil in an amount of 1% by weight or more and 5% by weight or less. The selection step includes a step of selecting a high-temperature lubricating reagent in a temperature range in which the decomposition start temperature exceeds 90 ° C. from among the additives that improve the lubricating characteristics.
The method for producing a lubricating composition according to claim 1, wherein the blending step includes a step of blending the selected lubricating reagent for high temperature into a base oil. With an old dam link made of iron or aluminum alloy, which has a protruding key,
A keyway into which the key is inserted is formed, and a member made of a material different from that of the Oldham link is provided.
A compressor supplied with a lubricating composition produced by the production method according to claim 1 or 2, wherein the member is made of an aluminum alloy or iron. A freezing system including the compressor according to claim 3. Base oil and
Lubricating reagents selected from additives that improve lubrication characteristics and exhibiting a thermogravimetric change of 0.675% or more and 0.825% or less in the temperature range of 70 ° C. or higher and 90 ° C. or lower.
The lubricating reagent contains
A lubricating composition containing 1% by weight or more and 5% by weight or less with respect to the base oil.

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